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Browse Health
Pediatrician
21 years of experience
Accepting new patients
Video profile

Credentials

Education ?

Medical School Score Rankings
Temple University Physicians (1991)
  •  
Top 50%

Awards & Distinctions ?

Awards  
Castle Connolly's Top Doctors™ (2012 - 2013)
Patients' Choice Award (2008 - 2011, 2013 - 2015)
Compassionate Doctor Recognition (2010 - 2011, 2013 - 2015)
On-Time Doctor Award (2014 - 2015)
Associations
American Board of Pediatrics

Affiliations ?

Dr. Rice is affiliated with 4 hospitals.

Hospital Affiliations

Score

Rankings

  • Lehigh Valley Hospital *
    1200 S Cedar Crest Blvd, Allentown, PA 18103
    •  
    Top 25%
  • Lehigh Valley Hospital - Muhlenberg
    2545 Schoenersville Rd, Bethlehem, PA 18017
    •  
    Top 25%
  • Muhlenberg Hospital Center
  • Lehigh Valley Hospital - Allentown Campuses
  • * This information was reported to Vitals by the doctor or doctor's office.

    Publications & Research

    Dr. Rice has contributed to 207 publications.
    Title Herpes Simplex Virus-induced Epithelial Damage and Susceptibility to Human Immunodeficiency Virus Type 1 Infection in Human Cervical Organ Culture.
    Date December 2011
    Journal Plos One
    Excerpt

    Normal human premenopausal cervical tissue has been used to derive primary cell populations and to establish ex vivo organ culture systems to study infections with herpes simplex virus (HSV-1 or HSV-2) and human immunodeficiency virus type 1 (HIV-1). Infection with either HSV-1 or HSV-2 rapidly induced multinuclear giant cell formation and widespread damage in mucosal epithelial cells. Subsequent exposure of the damaged mucosal surfaces to HIV-1 revealed frequent co-localization of HSV and HIV-1 antigens. The short-term organ culture system provides direct experimental support for the epidemiological findings that pre-existing sexually transmitted infections, including primary and recurrent herpes virus infections at mucosal surfaces, represent major risk factors for acquisition of primary HIV-1 infection. Epithelial damage in combination with pre-existing inflammation, as described here for overtly normal human premenopausal cervix, creates a highly susceptible environment for the initiation and establishment of primary HIV-1 infection in the sub-mucosa of the cervical transformation zone.

    Title Hydrodynamic Interactions in Ribbon Channels: from Quasi-one-dimensional to Quasi-two-dimensional Behavior.
    Date April 2011
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We present a study of the dynamics of confined suspensions whose dimensionality is intermediate between quasi-one-dimensional and quasi-two-dimensional (q2D) using microfluidic channels of various widths. The crossover between the two limiting behaviors is found to occur to different extent for different dynamic correlations between a pair of particles. In particular, the transverse coupling diffusion coefficient of particle pairs significantly deviates from its q2D form even in surprisingly wide channels.

    Title Characterisation and in Vitro Activities of Surface Attached Dihydropyrrol-2-ones Against Gram-negative and Gram-positive Bacteria.
    Date February 2011
    Journal Biofouling
    Excerpt

    Bacterial infection of biomedical devices is still a major barrier to their use. This is compounded by increasing antibiotic resistance. Here, the specific covalent attachment of a series of dihydropyrrol-2-one (DHP), analogues of bacterial quorum sensing inhibitors, to surfaces via a Michael-type addition reaction is described. Differences in efficiency of attachment related to the substituent groups were found by X-ray photoelectron spectroscopy. The physical characteristics of the surfaces were further explored by atomic force microscopy and contact angle measurements. The ability of these coatings to prevent the formation of a biofilm by Pseudomonas aeruginosa and Staphylococcus aureus was examined using confocal laser scanning microscopy and image analysis. The DHP-treated surfaces showed significant reductions in bacterial adhesion without increased killing for both strains of bacteria (p < 0.001). 5-Methylene-1-(prop-2-enoyl)-4-phenyl-dihydropyrrol-2-one was identified as having broad spectrum activity and consequently represents an excellent candidate for the development of novel surfaces for the prevention of biomedical device infections.

    Title Fight the Edifice Complex.
    Date July 2010
    Journal Science (new York, N.y.)
    Title New Ideas for Guiding the Evolution of a Quantum System.
    Date July 2010
    Journal Science (new York, N.y.)
    Title In-plane Structure of the Liquid-vapor Interface of an Alloy: A Grazing Incidence X-ray Diffraction Study of Bismuth:gallium.
    Date July 2010
    Journal Science (new York, N.y.)
    Excerpt

    The liquid-vapor interface of a bismuth-gallium mixture (0.2 percent bismuth and 99.8 percent gallium) at 36 degrees C has been studied by grazing incidence x-ray diffraction. The data show, in agreement with thermodynamic arguments, that bismuth is heavily concentrated in the liquid-vapor interface. The x-ray diffraction data are interpreted with the assistance of a simple model that represents the interface as a partial monolayer of bismuth. This analysis leads to the conclusion that the bismuth concentration in the interface is about 80 percent, that there is no significant mixing of gallium and bismuth in the interface, and that the structure function of the interfacial bismuth is like that of supercooled bulk liquid bismuth.

    Title Very Low Energy Cross Sections for Collision-induced Rotational Relaxation of I(2) Seeded in a Supersonic Free Jet.
    Date June 2010
    Journal Proceedings of the National Academy of Sciences of the United States of America
    Excerpt

    We report a study of rotational relaxation of I(2) seeded in He, Ne, and Ar free jets. It is inferred that in the very low collision energy range covered by these experiments the cross section for rotational relaxation is independent of energy.

    Title Comment on the Rotational State Dependence of Indirect Photodissociation of a Polyatomic Molecule.
    Date June 2010
    Journal Proceedings of the National Academy of Sciences of the United States of America
    Excerpt

    The rotational state dependence of indirect photodissociation has been examined in the light of some recent developments in the theory of radiationless transitions in rotating molecules. A simple argument based on projection operators leads to the prediction of sequential kinetics from an initial singlet state through an intermediate triplet bound state and on to a final dissociative state. The results indicate that as long as the geometry of the molecule in the triplet state is not very different from that of the singlet state, only a very small rotational dependence will show up in the singlet state radiationless lifetime, in spite of the fact that the overall dissociation constitutes a large geometry change.

    Title Starvation Response of the Marine Barophile Cnpt-3.
    Date June 2010
    Journal Applied and Environmental Microbiology
    Excerpt

    The psychrophilic marine barophile CNPT-3 underwent a starvation-survival response similar to that reported for the marine bacteria Ant-300, DW1, and S-14. The number of culturable cells increased initially and then decreased gradually over a 24-day starvation period, with corresponding decreases in total cell number and direct viability count. A significant reduction in cell size and biovolume accompanied these changes. Starved cells demonstrated a greater tendency to attach at the in situ pressure (400 atm; ca. 40.5 MPa) and temperature (5 degrees C) than at 1 atm (ca. 101 kPa), and the extent of attachment increased with increasing duration of starvation. The membrane fatty acid profile of the marine barophile CNPT-3 was studied as the cells were subjected to starvation conditions. A 37.5% increase in saturated fatty acids was observed during the first 8 days of starvation, with a concomitant decrease in unsaturated fatty acids. There was also an increase in the amount of short-chain (<C(15:0)) fatty acids.

    Title Spreading of Colloid Clusters in a Quasi-one-dimensional Channel.
    Date May 2010
    Journal The Journal of Chemical Physics
    Excerpt

    The effect of hydrodynamic interactions on the spreading of clusters of colloid particles in a quasi-one-dimensional channel is analyzed both experimentally and theoretically. An n-particle cluster spreading diffusion coefficient is defined, in terms of the displacement Deltax(t) in time t, by D(n)[triple bond]<[Sigma(i=1)(n)Deltax(i)(t)](2)>/2nt, where the average is taken over all groups of n adjacent particles. Our study focuses on the n-dependence of D(n) with some attention to the dependence of D(n) on colloid packing fraction. We find that the ratio of D(n) to the infinite dilution self-diffusion coefficient D(S)(0) increases as n increases, eventually saturating for large n. The observed dependence of D(n) on n is in satisfactory agreement with the predictions obtained from both Stokesian dynamics simulations and hydrodynamic calculations using the method of reflections.

    Title Atypical Presentation of Infiltrative Thyroid Dermopathy.
    Date May 2010
    Journal Clinical and Experimental Dermatology
    Excerpt

    A 46-year-old woman with Graves' disease developed infiltrative dermopathy of the thenar eminences. We believe this to be the first reported case of infiltrative dermopathy affecting the thenar eminences, and question whether repetitive occupational injury may have been a contributing factor. There is little published evidence to guide the treatment of infiltrative dermopathy.

    Title Identification of an Icp27-responsive Element in the Coding Region of a Herpes Simplex Virus Type 1 Late Gene.
    Date April 2010
    Journal Journal of Virology
    Excerpt

    During productive herpes simplex virus type 1 (HSV-1) infection, a subset of viral delayed-early (DE) and late (L) genes require the immediate-early (IE) protein ICP27 for their expression. However, the cis-acting regulatory sequences in DE and L genes that mediate their specific induction by ICP27 are unknown. One viral L gene that is highly dependent on ICP27 is that encoding glycoprotein C (gC). We previously demonstrated that this gene is posttranscriptionally transactivated by ICP27 in a plasmid cotransfection assay. Based on our past results, we hypothesized that the gC gene possesses a cis-acting inhibitory sequence and that ICP27 overcomes the effects of this sequence to enable efficient gC expression. To test this model, we systematically deleted sequences from the body of the gC gene and tested the resulting constructs for expression. In so doing, we identified a 258-bp "silencing element" (SE) in the 5' portion of the gC coding region. When present, the SE inhibits gC mRNA accumulation from a transiently transfected gC gene, unless ICP27 is present. Moreover, the SE can be transferred to another HSV-1 gene, where it inhibits mRNA accumulation in the absence of ICP27 and confers high-level expression in the presence of ICP27. Thus, for the first time, an ICP27-responsive sequence has been identified in a physiologically relevant ICP27 target gene. To see if the SE functions during viral infection, we engineered HSV-1 recombinants that lack the SE, either in a wild-type (WT) or ICP27-null genetic background. In an ICP27-null background, deletion of the SE led to ICP27-independent expression of the gC gene, demonstrating that the SE functions during viral infection. Surprisingly, the ICP27-independent gC expression seen with the mutant occurred even in the absence of viral DNA synthesis, indicating that the SE helps to regulate the tight DNA replication-dependent expression of gC.

    Title Herpes Simplex Virus Type 1 Immediate-early Protein Icp22 is Required for Vice Domain Formation During Productive Viral Infection.
    Date March 2010
    Journal Journal of Virology
    Excerpt

    During productive infection, herpes simplex virus type 1 (HSV-1) induces the formation of discrete nuclear foci containing cellular chaperone proteins, proteasomal components, and ubiquitinated proteins. These structures are known as VICE domains and are hypothesized to play an important role in protein turnover and nuclear remodeling in HSV-1-infected cells. Here we show that VICE domain formation in Vero and other cells requires the HSV-1 immediate-early protein ICP22. Since ICP22 null mutants replicate efficiently in Vero cells despite being unable to induce VICE domain formation, it can be concluded that VICE domain formation is not essential for HSV-1 productive infection. However, our findings do not exclude the possibility that VICE domain formation is required for viral replication in cells that are nonpermissive for ICP22 mutants. Our studies also show that ICP22 itself localizes to VICE domains, suggesting that it could play a role in forming these structures. Consistent with this, we found that ICP22 expression in transfected cells is sufficient to reorganize the VICE domain component Hsc70 into nuclear inclusion bodies that resemble VICE domains. An N-terminal segment of ICP22, corresponding to residues 1 to 146, is critical for VICE domain formation in infected cells and Hsc70 reorganization in transfected cells. We previously found that this portion of the protein is dispensable for ICP22's effects on RNA polymerase II phosphorylation. Thus, ICP22 mediates two distinct regulatory activities that both modify important components of the host cell nucleus.

    Title The Quasi-one-dimensional Colloid Fluid Revisited.
    Date February 2010
    Journal The Journal of Physical Chemistry. B
    Excerpt

    We report the results of studies of the pair correlation function and equation of state of a quasi-one-dimensional colloid suspension, focusing attention on the behavior in the density range near close packing. Our data show that, despite deviations from true one-dimensional geometry, the colloid fluid is well described as a hard rod Tonks fluid. In our experimental realization, the colloid suspension does not wet the confining walls, one consequence of which is a surface tension induced weak attractive interaction between the particles. The reality of this interaction is confirmed after correction of the raw experimental data for overlap of the optical images of particles that are nearly in contact and by an alternative particle location algorithm based on edge location.

    Title Nitric Oxide Signaling in Pseudomonas Aeruginosa Biofilms Mediates Phosphodiesterase Activity, Decreased Cyclic Di-gmp Levels, and Enhanced Dispersal.
    Date November 2009
    Journal Journal of Bacteriology
    Excerpt

    Bacteria in biofilms often undergo active dispersal events and revert to a free-swimming, planktonic state to complete the biofilm life cycle. The signaling molecule nitric oxide (NO) was previously found to trigger biofilm dispersal in the opportunistic pathogen Pseudomonas aeruginosa at low, nontoxic concentrations (N. Barraud, D. J. Hassett, S. H. Hwang, S. A. Rice, S. Kjelleberg, and J. S. Webb, J. Bacteriol. 188:7344-7353, 2006). NO was further shown to increase cell motility and susceptibility to antimicrobials. Recently, numerous studies revealed that increased degradation of the secondary messenger cyclic di-GMP (c-di-GMP) by specific phosphodiesterases (PDEs) triggers a planktonic mode of growth in eubacteria. In this study, the potential link between NO and c-di-GMP signaling was investigated by performing (i) PDE inhibitor studies, (ii) enzymatic assays to measure PDE activity, and (iii) direct quantification of intracellular c-di-GMP levels. The results suggest a role for c-di-GMP signaling in triggering the biofilm dispersal event induced by NO, as dispersal requires PDE activity and addition of NO stimulates PDE and induces the concomitant decrease in intracellular c-di-GMP levels in P. aeruginosa. Furthermore, gene expression studies indicated global responses to low, nontoxic levels of NO in P. aeruginosa biofilms, including upregulation of genes involved in motility and energy metabolism and downregulation of adhesins and virulence factors. Finally, site-directed mutagenesis of candidate genes and physiological characterization of the corresponding mutant strains uncovered that the chemotaxis transducer BdlA is involved in the biofilm dispersal response induced by NO.

    Title Pseudomonas Aeruginosa Pao1 Preferentially Grows As Aggregates in Liquid Batch Cultures and Disperses Upon Starvation.
    Date August 2009
    Journal Plos One
    Excerpt

    In both natural and artificial environments, bacteria predominantly grow in biofilms, and bacteria often disperse from biofilms as freely suspended single-cells. In the present study, the formation and dispersal of planktonic cellular aggregates, or 'suspended biofilms', by Pseudomonas aeruginosa in liquid batch cultures were closely examined, and compared to biofilm formation on a matrix of polyester (PE) fibers as solid surface in batch cultures. Plankton samples were analyzed by laser-diffraction particle-size scanning (LDA) and microscopy of aggregates. Interestingly, LDA indicated that up to 90% of the total planktonic biomass consisted of cellular aggregates in the size range of 10-400 microm in diameter during the growth phase, as opposed to individual cells. In cultures with PE surfaces, P. aeruginosa preferred to grow in biofilms, as opposed to planktonicly. However, upon carbon, nitrogen or oxygen limitation, the planktonic aggregates and PE-attached biofilms dispersed into single cells, resulting in an increase in optical density (OD) independent of cellular growth. During growth, planktonic aggregates and PE-attached biofilms contained densely packed viable cells and extracellular DNA (eDNA), and starvation resulted in a loss of viable cells, and an increase in dead cells and eDNA. Furthermore, a release of metabolites and infective bacteriophage into the culture supernatant, and a marked decrease in intracellular concentration of the second messenger cyclic di-GMP, was observed in dispersing cultures. Thus, what traditionally has been described as planktonic, individual cell cultures of P. aeruginosa, are in fact suspended biofilms, and such aggregates have behaviors and responses (e.g. dispersal) similar to surface associated biofilms. In addition, we suggest that this planktonic biofilm model system can provide the basis for a detailed analysis of the synchronized biofilm life cycle of P. aeruginosa.

    Title Structure of Quasi-one-dimensional Ribbon Colloid Suspensions.
    Date June 2009
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report the results of an experimental study of a colloid fluid confined to a quasi-one-dimensional (q1D) ribbon channel as a function of channel width and colloid density. Our findings confirm the principal predictions of previous theoretical studies of such systems. These are (1) that the density distribution of the liquid transverse to the ribbon channel exhibits stratification; (2) that even at the highest density the order along the strata, as measured by the longitudinal pair correlation function, is characteristic of a liquid; and (3) the q1D pair correlation functions in different strata exhibit anisotropic behavior resembling that found in a Monte Carlo simulation for the in-plane pair correlation function of a hard sphere fluid in a planar slit.

    Title A Conjecture Concerning the Symmetries of Planar Nets and the Hard Disk Freezing Transition.
    Date May 2009
    Journal The Journal of Physical Chemistry. B
    Excerpt

    We examine the conjecture that in a 2D system of hard disks the packing fraction at which the continuous transition from the ordered 2D solid to the hexatic phase occurs, and that at which the very weak first-order or continuous transition from the hexatic to the fluid phase occurs, can be correlated with the packing fractions of patterned networks (tessellations) of disk positions that span the 2D space. We identify three tessellations that have less than close packed density, span 2D space, and have percolated continuity of disk-disk contact. One has a packing fraction of eta = 0.729, very slightly larger than the estimated packing fraction at the ordered solid-to-hexatic transition, eta = 0.723, and the other two have packing fractions of approximately 0.680, slightly smaller than that identified as the upper end of the stability range of the liquid phase, eta = 0.699. The region 0.680 < eta < 0.729 is identified with the hexatic domain. The end points of this region can be placed in correspondence with nets for which the defining unit structures are regular polygons, but not the hexatic domain, in which there are randomly dispersed clusters that need not be regular polygons. The densities at which the percolated tessellations span the 2D space are regarded as special points along the density axis. We suggest that the possibility of forming different symmetry nets with sensibly the same packing fraction is a geometric analogue of a bifurcation condition that divides the configuration space into qualitatively different domains, and that the onset and end of the hexatic region are correlated with such divisions of the configuration space.

    Title The Biofilm Life Cycle and Virulence of Pseudomonas Aeruginosa Are Dependent on a Filamentous Prophage.
    Date March 2009
    Journal The Isme Journal
    Excerpt

    Mature Pseudomonas aeruginosa biofilms undergo specific developmental events. Using a bacteriophage mutant, generated by deletion of the entire filamentous Pf4 prophage, we show that the phage is essential for several stages of the biofilm life cycle and that it significantly contributes to the virulence of P. aeruginosa in vivo. Here, we show for the first time that biofilms of the Pf4 phage-deficient mutant did not develop hollow centres or undergo cell death, typical of the differentiation process of wild-type (WT) P. aeruginosa PAO1 biofilms. Furthermore, microcolonies of the Pf4 mutant were significantly smaller in size and less stable compared with the WT biofilm. Small colony variants (SCVs) were detectable in the dispersal population of the WT biofilm at the time of dispersal and cell death, whereas no SCVs were detected in the effluent of the Pf4 mutant biofilm. This study shows that at the time when cell death occurs in biofilms of the WT, the Pf4 phage converts into a superinfective form, which correlates with the appearance of variants in the dispersal population. Unexpectedly, mice infected with the Pf4 mutant survived significantly longer than those infected with its isogenic WT strain, showing that Pf4 contributes to the virulence of P. aeruginosa. Hence, a filamentous prophage is a major contributor to the life cycle and adaptive behaviour of P. aeruginosa and offers an explanation for the prevalence of phage in this organism.

    Title Herpes Simplex Virus Type 1 Icp27 Induces P38 Mitogen-activated Protein Kinase Signaling and Apoptosis in Hela Cells.
    Date February 2009
    Journal Journal of Virology
    Excerpt

    The herpes simplex virus type 1 (HSV-1) protein ICP27 has been implicated in a variety of functions important for viral replication including host shutoff, viral gene expression, activation of mitogen-activated protein kinases p38 and Jun N-terminal protein kinase (JNK), and apoptosis inhibition. In the present study we sought to examine the functions of ICP27 in the absence of viral infection by creating stable HeLa cell lines that inducibly express ICP27. Here, we characterize two such cell lines and show that ICP27 expression is associated with a cellular growth defect. The observed defect is caused at least in part by the induction of apoptosis as indicated by caspase-3 activation, annexin V staining, and characteristic changes in cellular morphology. In an effort to identify the function of ICP27 responsible for inducing apoptosis, we show that ICP27 expression is sufficient to activate p38 signaling to a level that is similar to that observed during wild-type HSV-1 infection. However, ICP27 expression alone is unable to lead to a strong activation of JNK signaling. Using chemical inhibitors, we show that the ICP27-mediated activation of p38 signaling is responsible for the observed induction of apoptosis in the induced cell lines. Our findings suggest that during viral infection, ICP27 activates p38 and JNK signaling pathways via two distinct mechanisms. ICP27 directly activates p38 signaling, leading to stimulation of the host cell apoptotic pathways. In contrast, robust activation of JNK signaling by ICP27 requires one or more delayed early or late viral gene products and may be associated with the inhibition of apoptosis.

    Title Transient Ordering in a Quasi-two-dimensional Binary Liquid Near Freezing.
    Date January 2009
    Journal The Journal of Chemical Physics
    Excerpt

    We report the results of a theoretical study of locally ordered fluctuations in a quasi-two-dimensional (quasi-2D) binary hard sphere mixture as monitored by the aperture cross-correlation function. Systems with thickness less than two large hard sphere diameters were studied, over a range of large hard sphere density and relative concentration of large and small hard spheres in the liquid state, for two ratios of sphere diameters, 0.2 and 0.3. In several major respects the occurrence and character of the structured fluctuations in a quasi-2D binary hard sphere mixture have similarities with those in a quasi-2D one-component hard sphere fluid, as reported by Sheu and Rice [J. Chem. Phys. 128, 244517 (2008)]. Specifically, our studies establish that structured fluctuations with both hexagonal and square symmetries can be found in the liquid phase well below the freezing density and that the occurrence of particular structured fluctuations is correlated with the symmetry of the solid to which the liquid freezes. However, there is also a major difference, specifically, the presence of the smaller spheres in the binary mixture can suppress the occurrence of all structured fluctuations. We attribute the affect of a small volume fraction of small spheres in a dense binary mixture of small and large spheres on the occurrence of structured fluctuations to the unfavorable entropy change associated with demixing of the small and large spheres.

    Title On the Consistency, Extremal, and Global Properties of Counterdiabatic Fields.
    Date January 2009
    Journal The Journal of Chemical Physics
    Excerpt

    The control of population transfer can be affected by the adiabatic evolution of a system under the influence of an applied field. If the field is too rapidly varying or too weak, the conditions for adiabatic transfer are not satisfactorily met. We report the results of an analysis of properties of counterdiabatic fields (CDFs) that restore the adiabatic dynamics of a system by suppressing diabatic effects as they are generated. We observe that a CDF is not unique and find the one that has minimum intensity, and we provide natural upper and lower bounds to the integrated intensity of a CDF in terms of integrals of the eigenvalues of the system Hamiltonian. For Hamiltonians that are separable with respect to their parameters, we prove that the time integral of an associated CDF is path independent. Finally we explain why and when, in the neighborhood of an avoided crossing, a CDF can be approximated by Lorentzian pulses.

    Title Identification of Sequences in Herpes Simplex Virus Type 1 Icp22 That Influence Rna Polymerase Ii Modification and Viral Late Gene Expression.
    Date January 2009
    Journal Journal of Virology
    Excerpt

    Previous studies have shown that the herpes simplex virus type 1 (HSV-1) immediate-early protein ICP22 alters the phosphorylation of the host cell RNA polymerase II (Pol II) during viral infection. In this study, we have engineered several ICP22 plasmid and virus mutants in order to map the ICP22 sequences that are involved in this function. We identify a region in the C-terminal half of ICP22 (residues 240 to 340) that is critical for Pol II modification and further show that the N-terminal half of the protein (residues 1 to 239) is not required. However, immunofluorescence analysis indicates that the N-terminal half of ICP22 is needed for its localization to nuclear body structures. These results demonstrate that ICP22's effects on Pol II do not require that it accumulate in nuclear bodies. As ICP22 is known to enhance viral late gene expression during infection of certain cultured cells, including human embryonic lung (HEL) cells, we used our engineered viral mutants to map this function of ICP22. It was found that mutations in both the N- and C-terminal halves of ICP22 result in similar defects in viral late gene expression and growth in HEL cells, despite having distinctly different effects on Pol II. Thus, our results genetically uncouple ICP22's effects on Pol II from its effects on viral late gene expression. This suggests that these two functions of ICP22 may be due to distinct activities of the protein.

    Title Liquid-to-hexatic Phase Transition in a Quasi-two-dimensional Colloid System.
    Date October 2008
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report an analysis of the thickness dependence of the liquid-to-hexatic phase transition in a quasi-two-dimensional hard-sphere colloid system as the confining wall separation changes from 1 to 1.6 hard-sphere diameters. In our theoretical evaluation, we study the bifurcation of solutions to the integral equation for the pair correlation function. Our study predicts that at small wall separation the liquid-to-hexatic phase transition is continuous and that it occurs at lower density than the liquid-to-crystal phase transition density, in agreement with the predictions for a strictly two-dimensional system obtained from the Kosterlitz-Thouless-Halperin-Nelson-Young theory. At larger wall separation (larger than about 1.4 hard-sphere diameters), the liquid-to-hexatic phase transition density is predicted to occur at higher density than the liquid-to-crystal phase transition.

    Title Role of Quorum Sensing by Pseudomonas Aeruginosa in Microbial Keratitis and Cystic Fibrosis.
    Date October 2008
    Journal Microbiology (reading, England)
    Excerpt

    Pseudomonas aeruginosa is a ubiquitous bacterium that causes opportunistic infections in a range of host tissues and organs. Infections by P. aeruginosa are difficult to treat and hence there is interest in the development of effective therapeutics. One of the key mechanisms that P. aeruginosa uses to control the expression of many virulence factors is the N-acylated homoserine lactone (AHL) regulatory system. Hence, there is considerable interest in targeting this regulatory pathway to develop novel therapeutics for infection control. P. aeruginosa is the principal cause of microbial keratitis and of infections in cystic fibrosis (CF) sufferers, and AHL-dependent cell-to-cell signalling has been shown to be important for both infection types. However, keratitis tends to be an acute infection whereas infection of CF patients develops into a chronic, life-long infection. Thus, it is unclear whether AHL-regulated virulence plays the same role during these infections. This review presents a comparison of the role of AHL signalling in P. aeruginosa-mediated microbial keratitis and chronic lung infections of CF patients.

    Title Hydrodynamic Description of the Long-time Tails of the Linear and Rotational Velocity Autocorrelation Functions of a Particle in a Confined Geometry.
    Date August 2008
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report a hydrodynamic analysis of the long-time behavior of the linear and angular velocity autocorrelation functions of an isolated colloid particle constrained to have quasi-two-dimensional motion, and compare the predicted behavior with the results of lattice-Boltzmann simulations. Our analysis uses the singularity method to characterize unsteady linear motion of an incompressible fluid. For bounded fluids we construct an image system with a discrete set of fundamental solutions of the Stokes equation from which we extract the long-time decay of the velocity. For the case that there are free slip boundary conditions at walls separated by H particle diameters, the time evolution of the parallel linear velocity and the perpendicular rotational velocity following impulsive excitation both correspond to the time evolution of a two-dimensional (2D) fluid with effective density rho_(2D)=rhoH. For the case that there are no slip boundary conditions at the walls, the same types of motion correspond to 2D fluid motions with a coefficient of friction xi=pi(2)nu/H(2) modulo a prefactor of order 1, with nu the kinematic viscosity. The linear particle motion perpendicular to the walls also experiences an effective frictional force, but the time dependence is proportional to t(-2) , which cannot be related to either pure 3D or pure 2D fluid motion. Our incompressible fluid model predicts correct self-diffusion constants but it does not capture all of the effects of the fluid confinement on the particle motion. In particular, the linear motion of a particle perpendicular to the walls is influenced by coupling between the density flux and the velocity field, which leads to damped velocity oscillations whose frequency is proportional to c_(s)/H , with c_(s) the velocity of sound. For particle motion parallel to no slip walls there is a slowing down of a density flux that spreads diffusively, which generates a long-time decay proportional to t(-1) .

    Title Herpes Simplex Virus Type 1 Icp27 Regulates Expression of a Variant, Secreted Form of Glycoprotein C by an Intron Retention Mechanism.
    Date July 2008
    Journal Journal of Virology
    Excerpt

    We previously showed that herpes simplex virus type 1 (HSV-1) immediate-early (IE) protein ICP27 can posttranscriptionally stimulate mRNA accumulation from a transfected viral late gene encoding glycoprotein C (gC) (K. D. Perkins, J. Gregonis, S. Borge, and S. A. Rice, J. Virol. 77:9872-9884, 2003). We began this study by asking whether ICP27 homologs from other herpesviruses can also mediate this activity. Although the homologs from varicella-zoster virus (VZV) and human cytomegalovirus (HCMV) were inactive, the homolog from bovine herpesvirus 4 (BHV-4), termed HORF1/2, was a very efficient transactivator. Surprisingly, most of the mRNA produced via HORF1/2 transactivation was 225 nucleotides shorter than expected due to the removal of a previously undescribed intron from the gC transcript. We found that the gC mRNA produced in the absence of transactivation was also mostly spliced. In contrast, gC mRNA produced by ICP27 transactivation was predominantly unspliced. Based on these results, we conclude that ICP27 has two distinct effects on the transfected gC gene: it (i) stimulates mRNA accumulation and (ii) promotes the retention of an intron. Interestingly, the spliced transcript encodes a variant of gC that lacks its transmembrane domain and is secreted from transfected cells. As the gC splicing signals are conserved among several HSV-1 strains, we investigated whether the variant gC is expressed during viral infection. We report here that both the spliced transcript and its encoded protein are readily detected in Vero cells infected with three different laboratory strains of wild-type HSV-1. Moreover, the variant gC is efficiently secreted from infected cells. We have designated this alternate form of the protein as gCsec. As the extracellular domain of gC is known to bind heparan sulfate-containing proteoglycans and to inhibit the complement cascade via an interaction with complement component C3b, we speculate that gCsec could function as a secreted virulence factor.

    Title A Fortunate Life in Physical Chemistry.
    Date July 2008
    Journal Annual Review of Physical Chemistry
    Excerpt

    This article contains a very personal account of my evolution as a physical chemist/chemical physicist, with commentary on some of the influences on that evolution and summary accounts of research accomplishments in four of the subject areas that have engaged my attention, ranging from isolated molecules to condensed matter.

    Title Quantum States of the Endohedral Fullerene Li@c60.
    Date July 2008
    Journal The Journal of Physical Chemistry. A
    Excerpt

    We present a theoretical study of the eigenstates of the endohedral fullerene Li@C60 for the case that the C 60 cage is assumed to be stationary. These eigenstates represent the three-dimensional nuclear dynamics of a Li atom confined to the interior of the carbon cage. The potential function employed, based on density functional theory calculations that we performed, has a variety of minima corresponding to complex hindered rotations of the Li atom in a shell about 1.5 A from the cage center. The energies and wave functions of the lowest 1200 states have been calculated, and the characteristic features of selected states and the far-IR spectrum are discussed. An interesting result of the calculations is the finding that the ground-state eigenfunction can become strongly localized when the cage atoms are just slightly perturbed from icosahedral symmetry.

    Title Detection and Inhibition of Bacterial Cell-cell Communication.
    Date July 2008
    Journal Methods in Molecular Biology (clifton, N.j.)
    Excerpt

    Bacteria communicate with other members of their community through the secretion and perception of small chemical cues or signals. The recognition of a signal normally leads to the expression of a large suite of genes, which in some bacteria are involved in the regulation of virulence factors, and as a result, these signaling compounds are key regulatory factors in many disease processes. Thus, it is of interest when studying pathogens to understand the mechanisms used to control the expression of virulence genes so that strategies might be devised for the control of those pathogens. Clearly, the ability to interfere with this process of signaling represents a novel approach for the treatment of bacterial infections. There is a broad range of compounds that bacteria can use for signaling purposes, including fatty acids, peptides, N-acylated homoserine lactones, and the signals collectively called autoinducer 2 (AI-2). This chapter will focus on the latter two signaling systems as they are present in a range of medically relevant bacteria, and here we describe assays for determining whether an organism produces a particular signal and assays that can be used to identify inhibitors of the signaling cascade. Lastly, the signal detection and inhibition assays will be directly linked to the expression of virulence factors of specific pathogens.

    Title Two-dimensional Freezing in the Liquid-vapor Interface of a Dilute Pb:ga Alloy.
    Date April 2008
    Journal Proceedings of the National Academy of Sciences of the United States of America
    Excerpt

    We report the results of x-ray reflectivity and grazing incidence x-ray diffraction studies of the liquid-vapor interface of a dilute alloy of Pb in Ga over the temperature range of 23-76 degrees C. Our data show that the liquid-vapor interface of this alloy is stratified for several atomic diameters into the bulk liquid and that a monolayer of Pb forms the outermost stratum of the interface. Over the temperature range of 23-56 degrees C, the monolayer of Pb is in an ordered hexagonal phase. At about 58 degrees C, this monolayer undergoes a first-order transition to a hexatic phase, which remains stable to 76 degrees C. An analogy between the observed transition and the first-order melting transition in a one-component classical plasma is suggested.

    Title Theoretical Study of Molecular Determinants Involved in Signal Binding to the Trar Protein of Agrobacterium Tumefaciens.
    Date January 2008
    Journal Molecules (basel, Switzerland)
    Excerpt

    N-acylated homoserine lactone (AHL) mediated cell-cell communication in bacteria is dependent on the recognition of the cognate signal by its receptor. This interaction allows the receptor-ligand complex to act as a transcriptional activator, controlling the expression of a range of bacterial phenotypes, including virulence factor expression and biofilm formation. One approach to determine the key features of signal- binding is to model the intermolecular interactions between the receptor and ligand using computational-based modeling software (LigandFit). In this communication, we have modeled the crystal structure of the AHL receptor protein TraR and its AHL signal N-(3- oxooctanoyl)-homoserine lactone from Agrobacterium tumefaciens and compared it to the previously reported antagonist behaviour of a number of AHL analogues, in an attempt to determine structural constraints for ligand binding. We conclude that (i) a common conformation of the AHL in the hydrophobic and hydrophilic region exists for ligand-binding, (ii) a tail chain length threshold of 8 carbons is most favourable for ligand-binding affinity, (iii) the positive correlation in the docking studies could be used a virtual screening tool.

    Title Infrared Multiphoton Induced Isomerization and Dissociation of Fcn, Clcn, and Brcn in Liquid Ar: a Classical Simulation Study.
    Date January 2008
    Journal The Journal of Chemical Physics
    Excerpt

    We report the results of classical mechanics simulations of infrared multiphoton induced control of isomerization of FCN, ClCN, and BrCN in liquid Ar, using ab initio potential energy and dipole moment surfaces for the XCN molecules. The field induced isomerization and fragmentation dynamics of these molecules are found to be different from that of HCN in liquid Ar. In particular, the scheme that provides complete controlled conversion of HCN to CNH in liquid Ar fails to generate complete conversion of XCN to CNX in liquid Ar for X=F,Cl,Br. It is suggested that the sources of the differences in behavior arise from differences in the spectra of vibrational nonlinear resonances in HCN and XCN and to the occurrence of monodromy in the dynamics of the XCN molecules.

    Title Herpes Simplex Virus Type 1 Immediate-early Protein Icp27 is Required for Efficient Incorporation of Icp0 and Icp4 into Virions.
    Date January 2008
    Journal Journal of Virology
    Excerpt

    Early in infection, herpes simplex virus type 1 (HSV-1) immediate-early (IE) proteins ICP0 and ICP4 localize to the nucleus, where they stimulate viral transcription. Later in infection, ICP0 and to a lesser extent ICP4 accumulate in the cytoplasm, but their biological role there is unknown. Previously, it was shown that the cytoplasmic localization of ICP0/4 requires the multifunctional IE protein ICP27, which is itself an activator of viral gene expression. Here, we identify a viral ICP27 mutant, d3-4, which is unable to efficiently localize ICP0 and ICP4 to the cytoplasm but which otherwise resembles wild-type HSV-1 in its growth and viral gene expression phenotypes. These results genetically separate the function of ICP27 that affects ICP0/4 localization from its other functions, which affect viral growth and gene expression. As both ICP0 and ICP4 are known to be minor virion components, we used d3-4 to test the hypothesis that the cytoplasmic localization of these proteins is required for their incorporation into viral particles. Consistent with this conjecture, d3-4 virions were found to lack ICP0 in their tegument and to have greatly reduced levels of ICP4. Thus, the cytoplasmic localization of ICP0 and ICP4 appears to be a prerequisite for the assembly of these important transcriptional regulatory proteins into viral particles. Furthermore, our results show that ICP27 plays a previously unrecognized role in determining the composition of HSV-1 virions.

    Title Biofilm Differentiation and Dispersal in Mucoid Pseudomonas Aeruginosa Isolates from Patients with Cystic Fibrosis.
    Date November 2007
    Journal Microbiology (reading, England)
    Excerpt

    Intractable biofilm infections with Pseudomonas aeruginosa are the major cause of premature death associated with cystic fibrosis (CF). Few studies have explored the biofilm developmental cycle of P. aeruginosa isolates from chronically infected individuals. This study shows that such clinical isolates exhibit biofilm differentiation and dispersal processes similar to those of the better-studied laboratory P. aeruginosa strain PAO1 in the glass flow-cell (continuous-culture) biofilm model, albeit they are initially less adherent and their microcolonies are slower to develop and show heterogeneous, strain-specific variations in architecture. Confocal scanning laser microscopy combined with LIVE/DEAD viability staining revealed that in all CF biofilms bacterial cell death occurred in maturing biofilms, extending from the substratum to the central regions of mature microcolonies to varying degrees, depending on the strain. Bacteriophage activity was detected in the maturing biofilms of all CF strains examined and the amount of phage produced paralleled the degree of cell death seen in the biofilm. Some CF strains exhibited 'seeding dispersal' associated with the above phenomena, producing 'hollowing' as motile cells evacuated from the microcolony interiors as has been described for strain PAO1. Moreover, morphotypic cell variants were seen in the biofilm effluents of all CF strains. For those CF strains where marked cell death and seeding dispersal occurred in the microcolonies, variants were more diverse (up to five morphotypes) compared to those of strain PAO1 (two morphotypes). Given that variants of strain PAO1 have enhanced colonization traits, it seems likely that the similar biofilm dispersal events described here for CF strains contribute to the variability seen in clinical isolates and the overall persistence of the P. aeruginosa in the CF airway.

    Title Three-particle Correlation Functions of Quasi-two-dimensional One-component and Binary Colloid Suspensions.
    Date October 2007
    Journal The Journal of Chemical Physics
    Excerpt

    We report the results of experimental determinations of the triplet correlation functions of quasi-two-dimensional one-component and binary colloid suspensions in which the colloid-colloid interaction is short ranged. The suspensions studied range in density from modestly dilute to solid. The triplet correlation function of the one-component colloid system reveals extensive ordering deep in the liquid phase. At the same density the ordering of the larger diameter component in a binary colloid system is greatly diminished by a very small amount of the smaller diameter component. The possible utilization of information contained in the triplet correlation function in the theory of melting of a quasi-two-dimensional system is briefly discussed.

    Title Is the Silent Epidemic Keeping Patients Awake?
    Date October 2007
    Journal Journal of Clinical Sleep Medicine : Jcsm : Official Publication of the American Academy of Sleep Medicine
    Title A Theoretical Study of the Structure of the Liquid Ga-diamond (111) Interface.
    Date July 2007
    Journal The Journal of Chemical Physics
    Excerpt

    We present the results of a computer simulation study of the structure of the interface between liquid Ga and the (111) face of diamond, with which we reinterpret the findings from an x-ray reflectivity study of that interface [W. J. Huisman, J. F. Peters, M. J. Zwanenburg, S. A. de Vries, T. E. Derry, D. Abernathy, and J. F. van der Veen, Nature (London) 390, 379 (1997); Surf. Sci. 402-404, 866 (1998)]. That experimental study has been interpreted to show that the contact of Ga with the (111) face of diamond induces the formation of Ga(2) molecules for several layers into the bulk liquid, with the axes of the Ga(2) molecules in successive layers oriented perpendicular to the diamond surface. No driving force for the proposed formation of Ga(2) molecules is identified. The simulations reported in this paper are based on a model that permits chemical binding of Ga, as a dimer, to the C=C double bonds in the reconstructed (111) face of diamond, thereby identifying the driving force for dimerization. We show that an isolated pi complex with the Ga(2) axis perpendicular to the C=C double bond is stable. We then modify the pseudopotential-based self-consistent Monte Carlo simulation scheme for describing inhomogeneous liquid metals, using the calculated potential-energy surface of Ga(2)(C=C) in the region close to the diamond surface. In this model only the Ga adjacent to the diamond is composed of dimers. The interfacial density distribution obtained from the simulations predicts an x-ray reflectivity that is in good agreement with that observed.

    Title Assisted Adiabatic Passage Revisited.
    Date June 2007
    Journal The Journal of Physical Chemistry. B
    Excerpt

    We report the results of studies of various aspects of the counter diabatic field paradigm, a recipe that generates adiabatic population transfer between levels by assisting a given field so that the total field generates the population transfer that the adiabatic approximation suggests for the given field. The sensitivity of this recipe to the pulse parameters and to Gaussian stochastic phase fluctuations between the fields has been investigated. Ladder-climbing population transfer between the vibrational levels of a nonrotating Morse oscillator is examined, and a numerical demonstration of the efficiency of the scheme is given.

    Title Pair Diffusion in Quasi-one- and Quasi-two-dimensional Binary Colloid Suspensions.
    Date June 2007
    Journal The Journal of Chemical Physics
    Excerpt

    The authors report the results of measurements of the center of mass and relative pair diffusion coefficients in quasi-one-dimensional (q1D) and quasi-two-dimensional (q2D) binary colloid suspensions. The new results extend the findings of similar studies of one-component quasi-one-dimensional and quasi-two-dimensional colloid suspensions. Our principal new finding is that the presence of the smaller diameter component can destroy the oscillatory structure of the separation dependence of the q2D relative pair diffusion coefficient of the large particles even though the oscillatory character of the large particle equilibrium pair correlation function remains prominent, and that no such effect occurs with the q1D suspension. An interpretation of these results is proposed.

    Title Herpes Simplex Virus Immediate-early Protein Icp22 Triggers Loss of Serine 2-phosphorylated Rna Polymerase Ii.
    Date June 2007
    Journal Journal of Virology
    Excerpt

    During eukaryotic mRNA transcription, the synthetic activity and mRNA processing factor interactions of RNA polymerase II (RNAP II) are regulated by phosphorylation of its carboxyl-terminal domain (CTD), with modification occurring primarily on serines 2 and 5 of the CTD. We previously showed that herpes simplex virus type 1 (HSV-1) infection rapidly triggers the loss of RNAP II forms bearing serine 2 phosphorylation (Ser-2P RNAP II). Here we show that the HSV-1 immediate-early (IE) protein ICP22 is responsible for this effect during the IE phase of infection. This activity does not require the viral UL13 protein kinase, which is required for several other regulatory functions of ICP22. Additionally, we show that transient expression of ICP22 can trigger the loss of Ser-2P RNAP II in transfected cells. Thus, the ability of ICP22 to cause the loss of Ser-2 RNAP II does not require other viral factors or the context of the infected cell. Expression of the HSV-1 ICP22-related protein US1.5, which corresponds to residues 147 to 420 of ICP22, also triggers a loss of Ser-2P RNAP II in transfected cells, whereas expression of the varicella-zoster virus ICP22 homolog, ORF63, does not. Our study also provides evidence for a second, viral late gene-dependent pathway that triggers loss of Ser-2P RNAP II in infected cells, consistent with the recent work of Dai-Ju et al. (J. Q. Dai-Ju, L. Li, L. A. Johnson, and R. M. Sandri-Goldin, J. Virol. 80:3567-3581, 2006). Therefore, it appears that HSV-1 has evolved redundant mechanisms for triggering the loss of a specific phosphorylated form of RNAP II.

    Title Quorum-sensing Regulation of Adhesion in Serratia Marcescens Mg1 is Surface Dependent.
    Date May 2007
    Journal Journal of Bacteriology
    Excerpt

    Serratia marcescens is an opportunistic pathogen and a major cause of ocular infections. In previous studies of S. marcescens MG1, we showed that biofilm maturation and sloughing were regulated by N-acyl homoserine lactone (AHL)-based quorum sensing (QS). Because of the importance of adhesion in initiating biofilm formation and infection, the primary goal of this study was to determine whether QS is important in adhesion to both abiotic and biotic surfaces, as assessed by determining the degree of attachment to hydrophilic tissue culture plates and human corneal epithelial (HCE) cells. Our results demonstrate that while adhesion to the abiotic surface was AHL regulated, adhesion to the HCE cell biotic surface was not. Type I fimbriae were identified as the critical adhesin for non-QS-mediated attachment to the biotic HCE cell surface but played no role in adhesion to the abiotic surface. While we were not able to identify a single QS-regulated adhesin essential for attachment to the abiotic surface, four AHL-regulated genes involved in adhesion to the abiotic surface were identified. Interestingly, two of these genes, bsmA and bsmB, were also shown to be involved in adhesion to the biotic surface in a non-QS-controlled fashion. Therefore, the expression of these two genes appears to be cocontrolled by regulators other than the QS system for mediation of attachment to HCE cells. We also found that QS in S. marcescens regulates other potential cell surface adhesins, including exopolysaccharide and the outer membrane protein OmpX. We concluded that S. marcescens MG1 utilizes different regulatory systems and adhesins in attachment to biotic and abiotic surfaces and that QS is a main regulatory pathway in adhesion to an abiotic surface but not in adhesion to a biotic surface.

    Title Phase Transitions in the Liquid-vapor Interface of Dilute Alloys of Bi in Ga: New Experimental Studies.
    Date April 2007
    Journal The Journal of Chemical Physics
    Excerpt

    We report the results of measurements of x-ray reflectivity and grazing incidence x-ray diffraction from the liquid-vapor interfaces of four dilute alloys of Bi in Ga with mole fractions x(Bi)=0.0032, 0.0023, 0.00037, and 0.000037. The monolayer coverage of the alloys with x(Bi)=0.0023, and x(Bi)=0.00037 is about 0.85 and only very slightly temperature dependent. The monolayer coverage in the lowest-concentration alloy, with x(Bi)=0.000037, ranged from 0.82 at 29 degrees C to 0.58 at 110 degrees C. In none of these alloys, down to the lowest temperature used, 29 degrees C, can we find any evidence for crystallization of the Bi monolayer that segregates as the outermost stratum of the liquid-vapor interface. Drawing on theoretical arguments we propose that the transitions inferred from the second-harmonic generation and plasma generation studies of dilute Bi in Ga alloys are from the liquid state to the hexatic state of the Bi monolayer. The data for the alloy with x(Bi)=0.000037 suggest that near 80 degrees C there is a disordered phase-to-disordered phase transition.

    Title Bacterial Quorum Sensing and Interference by Naturally Occurring Biomimics.
    Date March 2007
    Journal Analytical and Bioanalytical Chemistry
    Excerpt

    Bacteria are able to coordinate gene expression as a community through the secretion and detection of signalling molecules so that the members of the community can simultaneously express specific behaviours. This mechanism of regulation of behaviour appears to be a key trait for adaptation to specific environments and has been shown to regulate a variety of important phenotypes, from virulence factor production to biofilm formation to symbiosis related behaviours such as bioluminescence. The ability to communicate and communally regulate gene expression is hypothesised to have evolved as a way for organisms to delay expression of phenotypes until numerical supremacy is reached. For example, in the case of infection, if an invading microorganism were to express virulence factors too early, the host may be able to mount a successful defence and repel the invaders. There is growing evidence that bacterial quorum sensing (QS) systems are involved in cross-kingdom signalling with eukaryotic organisms and that eukaryotes are capable of actively responding to bacteria in their environment by detecting and acting upon the presence of these signalling molecules. Likewise, eukaryotes produce compounds that can interfere with QS systems in bacteria by acting as agonists or antagonists. An exciting new field of study, biomimetics, takes inspiration from nature's models and attempts to design solutions to human problems, and biomimics of QS systems may be one such solution. This article presents the acylated homoserine lactone and autoinducer 2 QS systems in bacteria, the means of intercepting or interfering with bacterial QS systems evolved by eukaryotes, and the rational design of synthetic antagonists.

    Title Controlled Subnanosecond Isomerization of Hcn to Cnh in Solution.
    Date March 2007
    Journal The Journal of Chemical Physics
    Excerpt

    We report a study of control of the HCN-->CNH isomerization in a liquid Ar solution. We show, using molecular dynamics simulations, nearly complete conversion from HCN to CNH can be achieved in solution on the subnanosecond time scale without requiring laser pulse shaping or molecular alignment. The mechanism of the isomerization reaction involves multiphoton rovibrational excitation on the ground electronic state potential energy surface coupled with rapid rovibrational relaxation in solution. The results demonstrate the important role of rotation-vibration coupling in multiphoton excitation of small molecules and constitute the first realistic computational demonstration of fast, robust, and high-yield laser field manipulation of solution-phase molecular processes.

    Title The Role of Quorum Sensing and the Effect of Environmental Conditions on Biofilm Formation by Strains of Vibrio Vulnificus.
    Date March 2007
    Journal Biofouling
    Excerpt

    It has been suggested that Vibrio vulnificus attaches to plankton and algae and is found in large numbers in the environment. Factors affecting attachment, biofilm formation and morphology of V. vulnificus have not been thoroughly investigated. This study evaluated the role of quorum sensing (QS) and environmental conditions on biofilm development of V. vulnificus. It was found that biofilm development by V. vulnificus was affected by nutrient and glucose concentration, but not by NaCl concentration or temperature under the conditions used here. Moreover, biofilm development of a QS mutant strain proceeded rapidly and sloughing occurred earlier than for the isogenic parent strain. There was a significant loss of viability for the QS mutant biofilm early in development. Hence, it is hypothesised that factors regulated by the QS system play a role in proper biofilm development and maintenance of V. vulnificus. Furthermore, it is shown that biofilm development varied among isolates.

    Title Phenotypic Diversification and Adaptation of Serratia Marcescens Mg1 Biofilm-derived Morphotypes.
    Date February 2007
    Journal Journal of Bacteriology
    Excerpt

    We report here the characterization of dispersal variants from microcolony-type biofilms of Serratia marcescens MG1. Biofilm formation proceeds through a reproducible process of attachment, aggregation, microcolony development, hollow colony formation, and dispersal. From the time when hollow colonies were observed in flow cell biofilms after 3 to 4 days, at least six different morphological colony variants were consistently isolated from the biofilm effluent. The timing and pattern of variant formation were found to follow a predictable sequence, where some variants, such as a smooth variant with a sticky colony texture (SSV), could be consistently isolated at the time when mature hollow colonies were observed, whereas a variant that produced copious amounts of capsular polysaccharide (SUMV) was always isolated at late stages of biofilm development and coincided with cell death and biofilm dispersal or sloughing. The morphological variants differed extensively from the wild type in attachment, biofilm formation, and cell ultrastructure properties. For example, SSV formed two- to threefold more biofilm biomass than the wild type in batch biofilm assays, despite having a similar growth rate and attachment capacity. Interestingly, the SUMV, and no other variants, was readily isolated from an established SSV biofilm, indicating that the SUMV is a second-generation genetic variant derived from SSV. Planktonic cultures showed significantly lower frequencies of variant formation than the biofilms (5.05 x 10(-8) versus 4.83 x 10(-6), respectively), suggesting that there is strong, diversifying selection occurring within biofilms and that biofilm dispersal involves phenotypic radiation with divergent phenotypes.

    Title Complete Quantum Control of the Population Transfer Branching Ratio Between Two Degenerate Target States.
    Date January 2007
    Journal The Journal of Chemical Physics
    Excerpt

    A five-level four-pulse phase-sensitive extended stimulated Raman adiabatic passage scheme is proposed to realize complete control of the population transfer branching ratio between two degenerate target states. The control is achieved via a three-node null eigenstate that can be correlated with an arbitrary superposition of the target states. Our results suggest that complete suppression of the yield of one of two degenerate product states, and therefore absolute selectivity in photochemistry, is achievable and predictable, even without studying the properties of the unwanted product state beforehand.

    Title Adiabatic Transfer of Population in a Dense Fluid: the Role of Dephasing Statistics.
    Date January 2007
    Journal The Journal of Chemical Physics
    Excerpt

    We report the results of simulation studies of the statistics of vibrational dephasing of a YCl (Y=H, D, T, and I) diatom in dense fluid Ar at two temperatures, including the effect of strong field driving on the energy level modulation statistics. The distribution of energy level modulations is found to be non-Gaussian with a high energy tail. Aspects of stimulated Raman adiabatic passage (STIRAP) between the vibrational levels of HCl in dense fluid Ar have been investigated. For HCl with nearly degenerate v=0-->v=1 and v=1-->v=2 transitions, the combined effect of modulation and power broadening reduces the STIRAP efficiency for population transfer from v=0 to v=2 of the order of 30%. However, if the transitions used have very different frequencies, as in the original model studied by Demirplak and Rice [J. Chem. Phys. 116, 8028 (2002)], the STIRAP efficiency for population transfer remains high, of the order of 80%, even with non-Gaussian modulation of energy levels.

    Title Influence of a Depletion Interaction on Dynamical Heterogeneity in a Dense Quasi-two-dimensional Colloid Liquid.
    Date December 2006
    Journal The Journal of Chemical Physics
    Excerpt

    We report the results of digital video microscopy studies of the large particle displacements in a quasi-two-dimensional binary mixture of large (L) and small (S) colloid particles with diameter ratio sigma(L)/sigma(S)=4.65, as a function of the large and small colloid particle densities. As in the case of the one-component quasi-two-dimensional colloid system, the binary mixtures exhibit structural and dynamical heterogeneity. The distribution of large particle displacements over the time scale examined provides evidence for (at least) two different mechanisms of motion, one associated with particles in locally ordered regions and the other associated with particles in locally disordered regions. When rhoL*=Npisigma(L) (2)/4A< or =0.35, the addition of small colloid particles leads to a monotonic decrease in the large particle diffusion coefficient with increasing small particle volume fraction. When rhoL* > or =0.35 the addition of small colloid particles to a dense system of large colloid particles at first leads to an increase in the large particle diffusion coefficient, which is then followed by the expected decrease of the large particle diffusion coefficient with increasing small colloid particle volume fraction. The mode coupling theory of the ideal glass transition in three-dimensional systems makes a qualitative prediction that agrees with the initial increase in the large particle diffusion coefficient with increasing small particle density. Nevertheless, because the structural and dynamical heterogeneities of the quasi-two-dimensional colloid liquid occur within the field of equilibrium states, and the fluctuations generate locally ordered domains rather than just disordered regions of higher and lower density, it is suggested that mode coupling theory does not account for all classes of relevant fluctuations in a quasi-two-dimensional liquid.

    Title Influence of Hydrodynamic Coupling on the Density Dependence of Quasi-one-dimensional Diffusion.
    Date December 2006
    Journal The Journal of Chemical Physics
    Excerpt

    The effect on the short time one particle diffusion coefficient of hydrodynamic interaction between pairs of colloid particles, and between colloid particles and the walls of a quasi-one-dimensional cylindrical channel, are calculated using the method of reflections. The nonzero size of the colloid particle is accounted for in the analysis, and the theoretical predictions are compared with the experimental data of Lin, Cui, Lee, and Yu for the short time one particle diffusion coefficient of colloids in a square open channel [Europhys. Lett. 57, 724 (2002)].

    Title Involvement of Nitric Oxide in Biofilm Dispersal of Pseudomonas Aeruginosa.
    Date December 2006
    Journal Journal of Bacteriology
    Excerpt

    Bacterial biofilms at times undergo regulated and coordinated dispersal events where sessile biofilm cells convert to free-swimming, planktonic bacteria. In the opportunistic pathogen Pseudomonas aeruginosa, we previously observed that dispersal occurs concurrently with three interrelated processes within mature biofilms: (i) production of oxidative or nitrosative stress-inducing molecules inside biofilm structures, (ii) bacteriophage induction, and (iii) cell lysis. Here we examine whether specific reactive oxygen or nitrogen intermediates play a role in cell dispersal from P. aeruginosa biofilms. We demonstrate the involvement of anaerobic respiration processes in P. aeruginosa biofilm dispersal and show that nitric oxide (NO), used widely as a signaling molecule in biological systems, causes dispersal of P. aeruginosa biofilm bacteria. Dispersal was induced with low, sublethal concentrations (25 to 500 nM) of the NO donor sodium nitroprusside (SNP). Moreover, a P. aeruginosa mutant lacking the only enzyme capable of generating metabolic NO through anaerobic respiration (nitrite reductase, DeltanirS) did not disperse, whereas a NO reductase mutant (DeltanorCB) exhibited greatly enhanced dispersal. Strategies to induce biofilm dispersal are of interest due to their potential to prevent biofilms and biofilm-related infections. We observed that exposure to SNP (500 nM) greatly enhanced the efficacy of antimicrobial compounds (tobramycin, hydrogen peroxide, and sodium dodecyl sulfate) in the removal of established P. aeruginosa biofilms from a glass surface. Combined exposure to both NO and antimicrobial agents may therefore offer a novel strategy to control preestablished, persistent P. aeruginosa biofilms and biofilm-related infections.

    Title Icp22 is Required for Wild-type Composition and Infectivity of Herpes Simplex Virus Type 1 Virions.
    Date October 2006
    Journal Journal of Virology
    Excerpt

    The immediate-early regulatory protein ICP22 is required for efficient replication of herpes simplex virus type 1 in some cell types (permissive) but not in others (restrictive). In mice infected via the ocular route, the pathogenesis of an ICP22- virus, 22/n199, was altered relative to that of wild-type virus. Specifically, tear film titers of 22/n199-infected mice were significantly reduced at 3 h postinfection relative to those of mice infected with wild-type virus. Further, 22/n199 virus titers were below the level of detection in trigeminal ganglia (TG) during the first 9 days postinfection. On day 30 postinfection, TG from 22/n199-infected mice contained reduced viral genome loads and exhibited reduced expression of latency-associated transcripts and reduced reactivation efficiency relative to TG from wild-type virus-infected mice. Notably, the first detectable alteration in the pathogenesis of 22/n199 in these tests occurred in the eye prior to the onset of nascent virus production. Thus, ICP22- virions appeared to be degraded, cleared, or adsorbed more rapidly than wild-type virions, implying potential differences in the composition of the two virion types. Analysis of the protein composition of purified extracellular virions indicated that ICP22 is not a virion component and that 22/n199 virions sediment at a reduced density relative to wild-type virions. Although similar to wild-type virions morphologically, 22/n199 virions contain reduced amounts of two gamma2 late proteins, US11 and gC, and increased amounts of two immediate-early proteins, ICP0 and ICP4, as well as protein species not detected in wild-type virions. Although ICP22- viruses replicate to near-wild-type levels in permissive cells, the virions produced in these cells are biochemically and physically different from wild-type virions. These virion-specific differences in ICP22- viruses add a new level of complexity to the functional analysis of this immediate-early viral regulatory protein.

    Title Icp27-dependent Resistance of Herpes Simplex Virus Type 1 to Leptomycin B is Associated with Enhanced Nuclear Localization of Icp4 and Icp0.
    Date October 2006
    Journal Virology
    Excerpt

    It was previously shown that herpes simplex virus type 1 (HSV-1) is sensitive to leptomycin B (LMB), an inhibitor of nuclear export factor CRM1, and that a single methionine to threonine change at residue 50 (M50T) of viral immediate-early (IE) protein ICP27 can confer LMB resistance. In this work, we show that deletion of residues 21-63 from ICP27 can also confer LMB resistance. We further show that neither the M50T mutation nor the presence of LMB affects the nuclear shuttling activity of ICP27, suggesting that another function of ICP27 determines LMB resistance. A possible clue to this function emerged when it was discovered that LMB treatment of HSV-1-infected cells dramatically enhances the cytoplasmic accumulation of two other IE proteins, ICP0 and ICP4. This effect is completely dependent on ICP27 and is reversed in cells infected with LMB-resistant mutants. Moreover, LMB-resistant mutations in ICP27 enhance the nuclear localization of ICP0 and ICP4 even in the absence of LMB, and this effect can be discerned in transfected cells. Thus, the same amino (N)-terminal region of ICP27 that determines sensitivity to LMB also enhances ICP27's previously documented ability to promote the cytoplasmic accumulation of ICP4 and ICP0. We speculate that ICP27's effects on ICP4 and ICP0 may contribute to HSV-1 LMB sensitivity.

    Title Measurement-assisted Coherent Control.
    Date September 2006
    Journal The Journal of Chemical Physics
    Excerpt

    Two advantageous roles of the influence of measurement on a system subject to coherent control are exposed using a five-level model system. In particular, a continuous measurement of the population in a branch state in the Kobrak-Rice extended stimulated Raman adiabatic passage scheme is shown to provide a powerful means for controlling the population transfer branching ratio between two degenerate target states. It is demonstrated that a measurement with a large strength may be used to completely shut off the yield of one target state and that the same measurement with a weak strength can dramatically enhance the robustness of the controlled branching ratio against dephasing.

    Title Adiabatic Population Transfer in a Liquid: Taking Advantage of a Decaying Target State.
    Date July 2006
    Journal The Journal of Chemical Physics
    Excerpt

    The feasibility of efficient population transfer between an initial state and a decaying target state of the same parity without populating an intermediate state, in the presence of large-amplitude stochastic energy level fluctuations that mimic the dephasing in a solute molecule due to the influence of a solvent, is demonstrated theoretically. In particular, it is shown that a decaying target state, whose decay rate constant is large compared with the band width of picosecond laser pulses but small compared with the associated peak Rabi frequencies, can dramatically suppress the dephasing-induced nonadiabaticity associated with the dynamics of population transfer, resulting in, irrespective of the correlation time of stochastic energy level fluctuations, negligible population in the intermediate state and complete population transfer to the decaying target state. These results should further motivate experimental studies of optical control of molecular dynamics in a liquid. An interesting connection between our results and the quantum Zeno and anti-Zeno effects is also discussed.

    Title Selective Photochemistry Via Adiabatic Passage: Degenerate Product States with Different Lifetimes.
    Date July 2006
    Journal The Journal of Chemical Physics
    Excerpt

    Two-pulse selective photochemistry that exploits population transfer via adiabatic passage is considered for the case that there are degenerate product states with different lifetimes. As an example, a four-level model system with a complex symmetric Hamiltonian is constructed. Analytical and numerical studies of this model system demonstrate that extensive control over the product branching ratio can be achieved by detuning either the pump pulse or the Stokes pulse while maintaining negligible population in the intermediate state. This control approach represents a significant simplification of both the Kobrak-Rice extended stimulated Raman adiabatic passage scheme and the Chen-Shapiro-Brumer strong-field control scheme.

    Title The Role of Quorum Sensing Mediated Developmental Traits in the Resistance of Serratia Marcescens Biofilms Against Protozoan Grazing.
    Date June 2006
    Journal Environmental Microbiology
    Excerpt

    Resistance against protozoan grazers is a crucial factor that is important for the survival of many bacteria in their natural environment. However, the basis of resistance to protozoans and how resistance factors are regulated is poorly understood. In part, resistance may be due to biofilm formation, which is known to protect bacteria from environmental stress conditions. The ubiquitous organism Serratia marcescens uses quorum sensing (QS) control to regulate virulence factor expression and biofilm formation. We hypothesized that the QS system of S. marcescens also regulates mechanisms that protect biofilms against protozoan grazing. To investigate this hypothesis, we compared the interactions of wild-type and QS mutant strains of S. marcescens biofilms with two protozoans having different feeding types under batch and flow conditions. Under batch conditions, S. marcescens forms microcolony biofilms, and filamentous biofilms are formed under flow conditions. The microcolony-type biofilms were protected from grazing by the suspension feeder, flagellate Bodo saltans, but were not protected from the surface feeder, Acanthamoeba polyphaga. In contrast, the filamentous biofilm provided protection against A. polyphaga. The main findings presented in this study suggest that (i) the QS system is not involved in grazing resistance of S. marcescens microcolony-type biofilms; (ii) QS in S. marcescens regulates antiprotozoan factor(s) that do not interfere with the grazing efficiency of the protozoans; and (iii) QS-controlled, biofilm-specific differentiation of filaments and cell chains in biofilms of S. marcescens provides an efficient mechanism against protozoan grazing.

    Title Isomerization and Dissociation Dynamics of Hcn in a Picosecond Infrared Laser Field: a Full-dimensional Classical Study.
    Date June 2006
    Journal The Journal of Chemical Physics
    Excerpt

    We report a full-dimensional study of the classical dynamics of HCN-->HNC isomerization and of HCN rovibrational dissociation driven by a strong but nonionizing picosecond infrared laser field. The dynamics of the isolated molecule and of the molecule in liquid Ar have both been studied. Our theoretical and numerical results show that when all degrees of freedom are accounted for the field induced molecular dynamics can be totally different from what was found in previous studies, where the HCN molecule is restricted to a plane containing the external field. It is shown that as HCN is driven by an infrared laser field, the rotation of the H atom around the C-N bond provides an important and highly efficient energy absorption mechanism. In the presence of a monochromatic picosecond infrared laser field with an intensity of 10(13) W/cm(2), this energy absorption mechanism generates considerable HCN-->HNC isomerization yield or high rovibrational dissociation yield without molecular preorientation or prealignment. Our study of the field induced isomerization and dissociation dynamics of the same system in liquid Ar shows that the picosecond isomerization dynamics is insignificantly affected by the surrounding atomic liquid whereas the dissociation yield may be greatly suppressed in a high density liquid. The implications of this study for full-dimensional quantum dynamics of multiphoton rovibrational excitation and dissociation of triatomics are briefly discussed.

    Title Depletion Interaction in a Quasi-two-dimensional Binary Colloid Mixture: Monte Carlo Simulations.
    Date May 2006
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report the results of extensive calculations of the depletion interaction between the large hard spheres in a quasi-two-dimensional (q2D) binary mixture of large and small hard spheres. Two definitions of the depletion interaction have been examined, and the dependencies of both on the large and small sphere densities, and the confining wall separation have been explored. The results of the simulations show that the depletion interaction is enhanced relative to its magnitude in a three-dimensional binary mixture with the same density, composition and sphere diameter ratio and that it has a complex dependence on the large sphere-large sphere separation. There are qualitative differences between the properties of q2D and mathematical 2D systems that are relevant to the interpretation of experimental data.

    Title Melting of Quasi-two-dimensional Crystalline Pb Supported on Liquid Ga.
    Date April 2006
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    Experimental studies have shown that the Pb monolayer that segregates in the PbGa alloy liquid-vapor interface forms a two-dimensional hexagonal crystal that melts at 341 K, and it has been speculated that the disordered phase formed is hexatic. This paper reports the results of simulation studies of the in-plane structure of the outermost stratum of the liquid-vapor interface of a dilute Pb in Ga alloy. These simulations are based on four major improvements to a previous study. First, the simulation studies involve considerably more atoms and considerably longer equilibration runs than considered in the previous work of Chekmarev, Oxtoby, and Rice. Second, a more accurate nonlocal pseudopotential representation of the interactions in the system is used. Third, the amplitude of the out-of-plane motion of the Pb atoms is constructed to have the observed value. Fourth, an approximation to the role of the liquid Ga substrate is provided by adding a layer of Ga atoms to the layer of Pb atoms. The results of our simulation studies show that the Ga layer adjacent to the Pb layer has a profound influence on that layer's properties. In particular, it is shown that in the two-layer PbGa system the Pb layer forms, at low temperature, a stable two-dimensional crystal on top of liquid Ga. This two-dimensional crystal melts at a temperature close to that found experimentally. It is found that the crystalline Pb layer is transformed to the liquid state via two intermediate hexatic phases that differ in the magnitude of the bond orientation order. Each of the phase transitions along this melting pathway is first order. The temperature range over which each hexatic phase is stable is small. The profound influence of out-of-plane motion is demonstrated by a comparison of the results of simulations of a quasi-two-dimensional (Q2D) and of a strictly two-dimensional monolayer of Pb. The melting transition in the Q2D one-layer system is first order, directly to the liquid, with no intervention of a hexatic phase. The melting transition in the strictly 2D system involves two stages: a first-order transition to an intermediate hexatic phase followed by melting of the hexatic to a liquid phase. The latter transition is continuous over a small temperature range. An examination of the role of defects in the melting process reveals a picture rather different from that postulated in the Kosterlitz-Thouless-Halperin-Nelson-Young theory of 2D melting.

    Title Anomalous Behavior of the Depletion Potential in Quasi-two-dimensional Binary Mixtures.
    Date March 2006
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report an experimental determination of the depletion interaction between a pair of large colloid particles present in a binary colloid mixture that has a high density of large particles and is tightly confined between two parallel plates, as a function of the small colloid particle density. The bare interaction between the large particles in the one component large colloid suspension, and the effective potential between the large particles in the binary colloid suspension represented as a pseudo-one-component fluid, were obtained by inverting the Ornstein-Zernike equation with the hypernetted chain closure. The depletion interaction is defined by subtracting the bare potential from the effective potential at fixed large colloid density. We find that the depletion potential in the quasi-two-dimensional (Q2D) system is purely attractive and short ranged as described by Asakura-Oosawa model. However, the depth of the depletion potential is found to be almost an order of magnitude larger than the counterpart depletion potential predicted for the same density and diameter ratio in a three-dimensional system. Although it is expected that the confining walls in the Q2D geometry enhance the excluded volume effects that generate entropic attraction, the observed enhancement is much larger than predicted for a Q2D binary mixture of hard spheres. We speculate that this anomalously strong confinement-induced depletion potential is a signature of characteristics of the real confined binary colloid mixture that are not included in any extant theory of the depletion interaction, specifically the omission of the role of the solvent in those theories. One such characteristic could be differential wall or particle wetting that generates a wall induced one-particle effective potential that confines the centers of the small particles to lie closer to the midplane between the walls than expected from the wall separation and the direct particle-wall interaction, thereby enhancing the depletion interaction.

    Title Influence of Hydrodynamic Coupling on Pair Diffusion in a Quasi-one-dimensional Colloid System.
    Date January 2006
    Journal Physical Review Letters
    Excerpt

    The effect of hydrodynamic interaction on the separation dependence of the center of mass and relative pair diffusion coefficients of colloid particles in a quasi-one-dimensional system, including the influence of proximate walls, is calculated using the method of reflections. There is excellent agreement between the theoretical predictions and the experimental data. We show that the separation dependence of the relative pair diffusion coefficient has an oscillatory structure on the scale length of the correlation length in the system, and we directly relate that oscillatory structure to the pair correlation function of the system.

    Title From Random Walk to Single-file Diffusion.
    Date January 2006
    Journal Physical Review Letters
    Excerpt

    We report an experimental study of diffusion in a quasi-one-dimensional (q1D) colloid suspension which behaves like a Tonks gas. The mean squared displacement as a function of time is described well with an ansatz encompassing a time regime that is both shorter and longer than the mean time between collisions. The ansatz asserts that the inverse mean squared displacement is the sum of the inverse mean squared displacement for short time normal diffusion (random walk) and the inverse mean squared displacement for asymptotic single-file diffusion (SFD). The dependence of the 1D mobility in the SFD on the concentration of the colloids agrees quantitatively with that derived for a hard rod model, which confirms for the first time the validity of the hard rod SFD theory. We also show that a recent SFD theory by Kollmann leads to the hard rod SFD theory for a Tonks gas.

    Title Grazing Resistance of Pseudomonas Aeruginosa Biofilms Depends on Type of Protective Mechanism, Developmental Stage and Protozoan Feeding Mode.
    Date October 2005
    Journal Environmental Microbiology
    Excerpt

    In a previous study we identified microcolony formation and inhibitor production as the major protective mechanisms of Pseudomonas aeruginosa biofilms against flagellate grazing. Here we compared the efficacy of these two key protective mechanisms by exposing biofilms of the non-toxic alginate overproducing strain PDO300 and the wild-type toxic strain PAO1 to a range of feeding types commonly found in the succession of protozoans associated with natural biofilms. Alginate-mediated microcolony formation conferred effective protection for strain PDO300 against the suspension feeding flagellate Bodo saltans and, as reported earlier, the surface feeding flagellate Rhynchomonas nasuta, both of which are considered as early biofilm colonizers. However, microcolonies of mature PDO300 biofilms were highly susceptible to late biofilm colonizers, the surface-feeding amoeba Acanthamoeba polyphaga and the planktonic ciliate Tetrahymena sp., resulting in a significant reduction of biofilm biomass. Mature biofilms of strain PAO1 inhibited growth of flagellates and A. polyphaga while the grazing activity of Tetrahymena sp. remained unaffected. Our findings suggest that inhibitor production of mature P. aeruginosa biofilms is effective against a wider range of biofilm-feeding predators while microcolony-mediated protection is only beneficial in the early stages of biofilm formation.

    Title Herpes Simplex Virus Type 1 Infection Leads to Loss of Serine-2 Phosphorylation on the Carboxyl-terminal Domain of Rna Polymerase Ii.
    Date September 2005
    Journal Journal of Virology
    Excerpt

    Previous studies have shown that herpes simplex virus type 1 (HSV-1) infection alters the phosphorylation of the carboxyl-terminal domain (CTD) of RNA polymerase II (RNAP II), creating a new form of the enzyme known as RNAP II(I). However, the specific phosphorylation changes induced by HSV-1 have not been characterized. In this study, we used phospho-specific anti-CTD antibodies to probe the structure of the postinfection RNAP II. We find that RNAP II(I) is phosphorylated on serine-5 (Ser-5) of the CTD consensus repeat but generally lacks phosphorylation on serine-2 (Ser-2). Since Ser-2 phosphorylation is normally associated with efficient transcriptional elongation and the recruitment of pre-mRNA processing factors, our results suggest that RNAP II(I) may have altered elongation properties and decreased interactions with the mRNA processing machinery. The viral factors responsible for the reduction in Ser-2 CTD phosphorylation were studied. We found that viral immediate-early (IE) gene expression is required and sufficient, in the context of infection, for loss of Ser-2 phosphorylation. However, studies with viral mutants failed to implicate a single IE protein (among ICP0, ICP4, ICP22, and ICP27) in this process. Although most Ser-2-phosphorylated RNAP II is lost after infection, our immunofluorescence analyses identified a small subfraction that escapes loss and relocalizes to splicing antigen-rich nuclear speckles. A similar phenomenon is seen in uninfected cells after various treatments that inhibit RNAP II transcription. We hypothesize that the HSV-1-induced relocalization of residual Ser-2-phosphorylated RNAP II to nuclear speckles reflects a host response to the inhibition of cellular gene transcription.

    Title Depletion Interaction in a Quasi-two-dimensional Colloid Assembly.
    Date September 2005
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We address several aspects of the character of the depletion interaction in a quasi-two-dimensional (Q2D) colloid system. First, we consider how, given information concerning the pair and triplet correlation functions, the depletion interaction can be efficiently and accurately determined. For this purpose we introduce a method based on the Born-Green equation using the assumption that for the Q2D binary mixtures of interest to us the depletion interaction is accurately represented as a sum of pair potentials. We then verify, by direct calculation, that three-particle contributions to the depletion interaction are negligibly small in the region of thermodynamic state space of interest to us. Second, we develop a representation of the dependence of the depletion interaction in a Q2D colloid system on the thickness of the confining parallel plates. Third, we report the results of extensive simulations of Q2D binary hard-sphere mixtures for a range of cell thickness, large and small particle number densities, and a ratio of sphere diameters q=0.3 .

    Title Influence of Polydispersity on the Effective Interaction in a Quasi-two-dimensional Pseudo-one-component Colloid Fluid.
    Date September 2005
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report the results of simulations of one-component and binary quasi-two-dimensional polydisperse hard sphere colloid fluids. When the polydisperse one-component system is regarded as an effective monodisperse one-component system, our results show that polydispersity gives rise to effective pair attraction and soft repulsion. These effective interactions depend on both the degree of polydispersity and the system density. At low density only the effective soft repulsion survives and the effective attraction becomes negligible. For the binary system, the depletion interaction develops extra features due to polydispersity, specifically a repulsive interaction with range twice the average particle diameter. At low density this extra feature vanishes. To carry out our study we have devised a method for continuous sampling of the polydisperse mixture according to a prescribed particle diameter distribution.

    Title Modeling the Effect of Acylated Homoserine Lactone Antagonists in Pseudomonas Aeruginosa.
    Date July 2005
    Journal Bio Systems
    Excerpt

    Pseudomonas aeruginosa is a gram-negative bacterium that causes serious illnesses, particularly in immunocompromised individuals, often with a fatal outcome. The finding that the acylated homoserine lactone quorum sensing (QS) system controls the production of virulence factors in P. aeruginosa makes this system a possible target for antimicrobial therapy. It has been suggested that an N-(3-oxododecanoyl)-homoserine lactone (3O-C12-HSL) antagonist, a QS blocker (QSB), would interfere efficiently with the quorum sensing system in P. aeruginosa and thus reduce the virulence of this pathogen. In this work, a mathematical model of the QS system in P. aeruginosa has been developed. The model was used to virtually add 3O-C12-HSL antagonists that differed in their affinity for the receptor protein and for their ability to mediate degradation of the receptor. The model suggests that very small differences in these parameters for different 3O-C12-HSL antagonists can greatly affect the success of QSB based inhibition of the QS system in P. aeruginosa. Most importantly, it is proposed that the ability of the 3O-C12-HSL antagonist to mediate degradation of LasR is the core parameter for successful QSB based inhibition of the QS system in P. aeruginosa. Finally, this study demonstrates that QSBs can shift the system to a low steady state, corresponding to an uninduced state and thus, suggests that the use of 3O-C12-HSL antagonists may constitute a promising therapeutic approach against P. aeruginosa involved infections.

    Title Biofilm Formation and Sloughing in Serratia Marcescens Are Controlled by Quorum Sensing and Nutrient Cues.
    Date June 2005
    Journal Journal of Bacteriology
    Excerpt

    We describe here a role for quorum sensing in the detachment, or sloughing, of Serratia marcescens filamentous biofilms, and we show that nutrient conditions affect the biofilm morphotype. Under reduced carbon or nitrogen conditions, S. marcescens formed a classical biofilm consisting of microcolonies. The filamentous biofilm could be converted to a microcolony-type biofilm by switching the medium after establishment of the biofilm. Similarly, when initially grown as a microcolony biofilm, S. marcescens could be converted back to a filamentous biofilm by increasing the nutrient composition. Under high-nutrient conditions, an N-acyl homoserine lactone quorum-sensing mutant formed biofilms that were indistinguishable from the wild-type biofilms. Similarly, other quorum-sensing-dependent behaviors, such as swarming motility, could be rendered quorum sensing independent by manipulating the growth medium. Quorum sensing was also found to be involved in the sloughing of the filamentous biofilm. The biofilm formed by the bacterium consistently sloughed from the substratum after approximately 75 to 80 h of development. The quorum-sensing mutant, when supplemented with exogenous signal, formed a wild-type filamentous biofilm and sloughed at the same time as the wild type, and this was independent of surfactant production. When we removed the signal from the quorum-sensing mutant prior to the time of sloughing, the biofilm did not undergo significant detachment. Together, the data suggest that biofilm formation by S. marcescens is a dynamic process that is controlled by both nutrient cues and the quorum-sensing system.

    Title Rehabilitation of Children with Traumatic Brain Injury: Descriptive Analysis of a Nationwide Sample Using the Weefim.
    Date May 2005
    Journal Archives of Physical Medicine and Rehabilitation
    Excerpt

    OBJECTIVE: To describe functional capability at admission and discharge of children with traumatic brain injury (TBI) in rehabilitation settings. DESIGN: Descriptive analysis. SETTING: Inpatient pediatric rehabilitation hospitals in the United States. PARTICIPANTS: Children (N=3815) in 56 pediatric inpatient rehabilitation facilities who were discharged during 1999 to 2001. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Admission and discharge WeeFIM scores. RESULTS: Admission and discharge WeeFIM scores correlated positively with age at admission, time from injury to rehabilitation admission, and length of stay (LOS). Higher admission WeeFIM scores correlated with shorter LOS, shorter time from injury to admission to rehabilitation, and higher discharge WeeFIM scores. CONCLUSIONS: Children with TBI demonstrated significant improvement in functional measures during rehabilitation. Discharge function and LOS correlated with admission severity, with children who had higher functional status and shorter time between injury and rehabilitation care having higher discharge function and shorter LOS.

    Title Macrocephaly, Corpus Callosum Morphology, and Autism.
    Date April 2005
    Journal Journal of Child Neurology
    Excerpt

    Although the cause of autism is undetermined, a general consensus has been that some type of early aberrant neural development underlies the disorder. Given the increased prevalence of macrocephaly in autism, one theory of abnormal neural development implicates early brain growth resulting in larger brain and head size in autism. Surface area measurements of the midsagittal section of the corpus callosum can be used as an index of neural development and white-matter integrity because the corpus callosum is the major white-matter structure that interconnects the two cerebral hemispheres. The purpose of this study was to obtain corpus callosum surface area, shape, and contour in a sample of non-mentally retarded autistic subjects with macrocephaly (n = 12) and compare them with those of matched (n = 8), typically developing control subjects with benign macrocephaly. No significant differences were found in surface area, shape, or contour between groups, nor did corpus callosum surface area relate to measures of IQ or picture vocabulary. These findings suggest no unique difference in overall regional corpus callosum surface area in autism with macrocephaly.

    Title The Use of Quorum-sensing Blockers As Therapeutic Agents for the Control of Biofilm-associated Infections.
    Date April 2005
    Journal Current Opinion in Investigational Drugs (london, England : 2000)
    Excerpt

    The development of novel antimicrobial compounds is required to treat the growing number of infections where antibiotic resistance is a serious threat, especially in situations where biofilms are involved. Antibiotic resistance is the result of two factors: first, through the development of specific antibiotic resistance, due to either mutation or the acquisition of antibiotic resistance genes; and second, by the innate tolerance of bacterial biofilms. Bacterial control, through the inhibition of bacterial cell-cell communication systems which are involved in the regulation of virulence factor production, host colonization, and biofilm formation, is discussed in this review. Specifically, this review presents current studies on the development of quorum-sensing inhibitors for the control of bacterial infections.

    Title Painful Attraction: a Magnetic Penile Injury.
    Date March 2005
    Journal Journal of the Royal Society of Medicine
    Title Anomalous Hydrodynamic Interaction in a Quasi-two-dimensional Suspension.
    Date March 2005
    Journal Physical Review Letters
    Excerpt

    We study the correlated Brownian motion of micron-sized particles suspended in water and confined between two plates. The hydrodynamic interaction between the particles exhibits three anomalies. (i) The transverse coupling is negative; i.e., particles exert "antidrag" on one another when moving perpendicular to their connecting line. (ii) The interaction decays with interparticle distance r as 1/r(2), faster than in unconfined suspensions but slower than near a single wall. (iii) At large distances, the pair interaction is independent of concentration within the experimental accuracy. The confined suspension thus provides an unusual example of long-range, yet essentially pairwise, correlations even at high concentration. These effects are shown to arise from the two-dimensional dipolar form of the flow induced by single-particle motion.

    Title Melting of a Quasi-two-dimensional Metallic System.
    Date September 2004
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We analyze the melting of a quasi-two-dimensional metallic system using the results of a series of Monte Carlo simulations of an array of Pb atoms. The system was chosen to model the melting behavior observed for the monolayer of Pb that segregates in the liquid-vapor interface of a dilute Pb in Ga alloy [B. Yang et al., Proc. Natl. Acad. Sci. USA 96, 13 009 (1999)]. Our calculations employed a realistic pair interaction potential between lead pseudoatoms, one that is known to describe accurately the properties of the three-dimensional metal near the melting point. Our results reveal that in the quasi-two-dimensional Pb system melting is a two-stage process which proceeds through formation of a stable intermediate hexatic phase, in agreement with the prediction of the Kosterlitz-Thouless-Halperin-Nelson-Young theory. Both the solid-to-hexatic and the hexatic-to-liquid transitions are found to be first order in our simulations.

    Title Pseudomonas Aeruginosa with Lasi Quorum-sensing Deficiency During Corneal Infection.
    Date July 2004
    Journal Investigative Ophthalmology & Visual Science
    Excerpt

    To understand the importance of Pseudomonas aeruginosa quorum-sensing systems in the development of corneal infection, the genotypic characteristics and pathogenesis of seven ocular isolates with low-protease and acyl homoserine lactone (AHL) activity and quorum-sensing mutants of PAO1 deficient in lasI, lasR, or rhlR were investigated in the study.

    Title Cerebral Volume Loss, Cognitive Deficit and Neuropsychological Performance: Comparative Measures of Brain Atrophy: I. Dementia.
    Date June 2004
    Journal Journal of the International Neuropsychological Society : Jins
    Excerpt

    There are several magnetic resonance (MR) imaging methods to measure brain volume and cerebral atrophy; however, the best measure for examining potential relationships between such measures and neuropsychological performance has not been established. Relationships between seven measures of MR derived brain volume or indices of atrophy and neuropsychological performance in the elderly subjects of the population-based Cache County, Utah Study of Aging and Memory (n = 195) were evaluated. The seven MR measures included uncorrected total brain volume (TBV), TBV corrected by total intracranial volume (TICV), TBV corrected by the ratio of the individuals TICV by group TICV (TBVC), a ventricle-to-brain ratio (VBR), total ventricular volume (TVV), TVV corrected by TICV, and a measure of parenchymal volume loss. The cases from the Cache County Study were comprised of elderly individuals classified into one of four subject groups based on a consensus diagnostic process, independent of quantitative MR imaging findings. The groups included subjects with Alzheimer's disease (AD, n = 85), no dementia but mild/ambiguous (M/A) deficits (n = 30), a group of subjects with non-AD dementia or neuropsychiatric disorder including vascular dementia (n = 60), and control subjects (n = 20). Neuropsychological performance was based on the Mini-Mental Status Exam (MMSE) and an expanded neuropsychological test battery (consortium to establish a registry for Alzheimer's disease (CERAD). The results demonstrated that the various quantitative MR measures were highly interrelated and no single measure was statistically superior. However, TBVC, TBV/TICV and VBR consistently exhibited the more robust relationships with neuropsychological performance. These results suggest that a single corrected brain volume measure or index is sufficient in studies examining global MR indicators of cerebral atrophy in relation to cognitive function and recommends use of either TBVC, TBV/TICV, or VBR.

    Title Phase Diagram of a Quasi-two-dimensional Colloid Assembly.
    Date June 2004
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    We report the results of simulations of the phase diagrams of a quasi-two-dimensional (Q2D) colloid assembly and of a two-dimensional (2D) colloid assembly which have the same colloid-colloid interaction. That interaction is the same as used in the study reported by Zangi and Rice [Phys. Rev. E 58, 7529 (1998)]. Among the goals of the work reported are elucidation of the influence of small amplitude out-of-plane motion on the phase diagram of a system and determination of the effect of that motion on the role of a hexatic phase in the melting process. Both of the systems we have studied undergo a first-order solid I-solid II and solid II-solid III isostructural transition induced by the attractive and repulsive components of the interaction, respectively. Introduction of the out-of-plane motion shifts the low density portion of the phase boundaries involving the solid II phase. The liquid-solid I coexistence line is nearly the same for the two systems. The solid II-solid III transition is shifted to lower temperature and shifted to higher density in the quasi-two-dimensional system. We further use the simulations to calculate the elastic constants, which can be used to predict the location of the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) melting transition. For the Q2D system we find that the first-order melting transition preempts the KTHNY transition for the reduced temperatures T(*)=1.00, 0.60, and 0.50. For the 2D system, when T(*)=0.60, the KTHNY transition barely preempts the first-order melting transition and when T(*)=1.00 and 0.50 the ordinary first-order transition preempts the KTHNY transition.

    Title Freezing Transition and Correlated Motion in a Quasi-two-dimensional Colloid Suspension.
    Date June 2004
    Journal Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
    Excerpt

    Recent experiments have demonstrated that the deviation of the single-particle displacement distribution from Gaussian form in a dense quasi-two-dimensional colloid suspension is a result of heterogenous dynamics that involves cooperative motions of neighboring colloid particles [J. Chem. Phys. 47, 9142 (2001)]. In this paper, we report the results of molecular dynamics (MD) simulations of a quasi-two-dimensional assembly of nearly hard-sphere colloid particles. The colloid-colloid interaction we use is short ranged and everywhere repulsive; it is related to the Marcus-Rice (MR) and modified MR interactions used in a previous study [Phys. Rev. E 58, 7529 (1998)]. As is the case for those systems, the one we study supports liquid, hexatic, and solid phases. Our calculations show that the deviation of the single-particle displacement distribution from Gaussian form is present in the liquid phase, and that a sharp increase in its magnitude occurs at the liquidus density and extends into the crystalline phase. For densities greater than the liquidus density we find three dynamical relaxation processes that include, at intermediate times, a slowing down in the rate of growth of the diffusive displacement of a particle due to the cage effect. As the density increases toward the solidus density, the dependence of the mean squared displacement on time, at intermediate times, changes from sublinear to zero. The onset of the long-time relaxation mode corresponds to the time at which the deviation of the particle displacement distribution from Gaussian form is a maximum. At this time, which increases exponentially with the density, the self-part of the van Hove function exhibits multiple maxima with respect to r while the distinct part of the van Hove function is a maximum at the origin, thereby signaling jump dynamics. At long times the particle mean square displacement has diffusive character at all densities including solid phase densities. A remarkable feature of our findings is the continuity of character of the particle displacement from the liquid phase through the hexatic phase and into the solid phase. Cooperative jumps that lead to diffusive process in crystals can be explained by a mechanism that involves many such correlated hops in random locations and random directions (but along the crystallographic axes) thereby generating effective random walk behavior. We argue that the collective motion we have found is generated by superpositions of instantaneous normal mode vibrations along diffusive paths. The diffusive paths are along the directions with strong bond orientation correlation, and start to grow in amplitude rapidly on entry into the hexatic phase.

    Title The Role of Regulators in the Expression of Quorum-sensing Signals in Pseudomonas Aeruginosa.
    Date June 2004
    Journal Journal of Molecular Microbiology and Biotechnology
    Excerpt

    Quorum-sensing systems provide Pseudomonas aeruginosa with a sensitive regulatory mechanism that allows for the induction of several phenotypic genes in a cell density fashion. In this work, a mathematical model of the acylated homoserine lactones regulatory network system in P. aeruginosa has been developed. It is the first integrated model to consider both quorum-sensing systems. The model has allowed us to disentangle the complex behavior exhibited by the system as the concentration of extracellular OdDHL is increased. At either low or high levels of extracellular OdDHL, the bacterium remains in an uninduced or induced state, respectively. At moderate levels, the behavior is characterized by several states. Here, the bacteria can switch suddenly from an uninduced to an induced phenotype in response to small changes in the concentration of extracellular OdDHL. Additionally, we have been able to address the roles of RsaL and Vfr as regulators of the quorum-sensing system. An important result from this analysis suggests that RsaL will increase the concentration of extracellular OdDHL required to induce the system, and it is a key regulator of the inhibition of the quorum-sensing system under low cell densities. Most importantly, our results suggest that Vfr has strong regulatory effects on the system as an increased affinity between the LasR/OdDHL complex, and the lasR promoter leads to significant qualitative changes in induction patterns. We also show experimental data that demonstrate that Vfr is required for signal production in the early phase of growth, but that in the latter stages of growth, the vfr mutant is able to synthesize wild-type levels of signal.

    Title Chemistry: Atom Tracking.
    Date May 2004
    Journal Nature
    Title Wavelength Dependence of Liquid-vapor Interfacial Tension of Ga.
    Date May 2004
    Journal Physical Review Letters
    Excerpt

    The wave-vector dependence of the liquid-vapor interfacial tension of Ga, gamma(q), has been determined from diffuse x-ray scattering measurements. The ratio gamma(q)/gamma(0)=1 for q<0.05 A(-1) decreases to 0.5 near q=0.22 A(-1), and increases strongly for larger q. The observed form for gamma(q)/gamma(0) is consistent with the prediction from the Mecke-Dietrich theory when the known stratified liquid-vapor interfacial density profile of Ga and a pseudopotential based pair interaction with appropriate asymptotic (r--> infinity ) behavior are used. The detailed behavior of gamma(q)/gamma(0) depends on the particular forms of both the interfacial density profile and the asymptotic falloff of the atomic pair interaction.

    Title Microcolonies, Quorum Sensing and Cytotoxicity Determine the Survival of Pseudomonas Aeruginosa Biofilms Exposed to Protozoan Grazing.
    Date April 2004
    Journal Environmental Microbiology
    Excerpt

    This study was based on the hypothesis that biofilms of the opportunistic pathogen Pseudomonas aeruginosa are successfully adapted to situations of protozoan grazing. We tested P. aeruginosa wild type and strains that were genetically altered, in structural and regulatory features of biofilm development, in response to the common surface-feeding flagellate Rhynchomonas nasuta. Early biofilms of the wild type showed the formation of grazing resistant microcolonies in the presence of the flagellate, whereas biofilms without the predator were undifferentiated. Grazing on biofilms of quorum sensing mutants (lasR and rhlR/lasR) also resulted in the formation of microcolonies, however, in lower numbers and size compared to the wild type. Considerably fewer microcolonies than the wild type were formed by mutant cells lacking type IV pili, whereas no microcolonies were formed by flagella-deficient cells. The alginate-overproducing strain PDO300 developed larger microcolonies in response to grazing. These observations suggest a role of quorum sensing in early biofilms and involvement of flagella, type IV pili, and alginate in microcolony formation in the presence of grazing. More mature biofilms of the wild type exhibited acute toxicity to the flagellate R. nasuta. Rapid growth of the flagellate on rhlR/lasR mutant biofilms indicated a key role of quorum sensing in the upregulation of lethal factors and in grazing protection of late biofilms. Both the formation of microcolonies and the production of toxins are effective mechanisms that may allow P. aeruginosa biofilms to resist protozoan grazing and to persist in the environment.

    Title Active Control of the Dynamics of Atoms and Molecules.
    Date April 2004
    Journal Annual Review of Physical Chemistry
    Excerpt

    There has been much progress in the control of chemical reactions since methods of active control were first proposed by Brumer & Shapiro and by Tannor & Rice ten years ago. This chapter reviews both theoretical and experimental advances in the field. Control schemes based on quantum mechanical interference between competing paths and the manipulation of wave packets with tailored laser pulses are discussed. The theory of optimal control, the limitations of control theory applied to many-body dynamics, and the effects of constraints on the trajectory of the controlled observable are presented. Experimental progress in controlling the population of specific quantum states, in manipulating the dynamics of bound wave packets, and in the control of chemical reactions are reviewed, and current problems in the field are summarized.

    Title Brain Imaging As a Predictor of Early Functional Outcome Following Traumatic Brain Injury in Children, Adolescents, and Young Adults.
    Date March 2004
    Journal The Journal of Head Trauma Rehabilitation
    Excerpt

    OBJECTIVES: A depth of lesion (DOL) model using brain imaging has been proposed to aid in medical decision-making and planning for rehabilitation resource needs. The purpose of this study was to determine the early prognostic value of a DOL classification system for children and young adults following severe traumatic brain injury. METHODS AND OUTCOME MEASURES: CT/MRI brain imaging studies on 92 patients, aged 3 to 21, admitted to the Kluge Children's Rehabilitation Center, University of Virginia, were evaluated to determine DOL. Images were classified according to 5 DOL levels (cortical to brainstem). Functional outcomes in mobility, self-care, and cognition, as rated on the WeeFIM instrument, were compared by DOL levels. RESULTS: Admission WeeFIM scores were significantly different for the DOL levels with the highest score for frontal and/or temporal lesions and the lowest for lesions including the brainstem or cerebellum (P<.001). However, the deeper the lesion, the greater the functional gains (P=.05), resulting in discharge WeeFIM scores that were not significantly different across DOL levels. Patients with deeper lesions tended to have longer lengths of stay in rehabilitation but were able to "catch up" with patients who had more superficial lesions. CONCLUSIONS: While relatively simple and convenient, the DOL classification system is limited in its usefulness as an early prognostic tool. It may not be possible to predict outcome in the early acute phase in the intensive care unit on the basis of standard brain imaging alone. Patients with deeper lesions may enter rehabilitation at a more impaired level but can make remarkable progress, though it may take longer than for less severely injured individuals.

    Title Reduced Hippocampal Volume in Alcohol and Substance Naïve Vietnam Combat Veterans with Posttraumatic Stress Disorder.
    Date February 2004
    Journal Cognitive and Behavioral Neurology : Official Journal of the Society for Behavioral and Cognitive Neurology
    Excerpt

    OBJECTIVE: This pilot study was undertaken to exclude the effects of alcohol and other substances on brain morphology in posttraumatic stress disorder. BACKGROUND: Posttraumatic stress disorder and alcohol use are among the conditions associated with decreased hippocampal volume. The possible confounding contribution of alcohol and other substances of abuse to decreased hippocampal volume in posttraumatic stress disorder has not been previously explored directly. METHOD: In this pilot study, magnetic resonance imaging scans of 4 substance naive subjects with combat-related posttraumatic stress disorder and of 4 controls were quantified. RESULTS: Bilateral hippocampal volumes were significantly smaller in posttraumatic stress disorder subjects. No significant differences were found between posttraumatic stress disorder subjects and the comparison group for total brain, gray and white matter, and ventricular volumes. CONCLUSIONS: These findings suggest that posttraumatic stress disorder in the absence of alcohol and other substance abuse may be associated with reduced hippocampal volume. The significance of reduced hippocampal volume in posttraumatic stress disorder is discussed.

    Title Cooperative Dynamics in Two Dimensions.
    Date February 2004
    Journal Physical Review Letters
    Excerpt

    We report results from molecular dynamics simulations of cooperative motion in a quasi-two-dimensional system of colloid particles. We find that the onset of the deviation of the single-particle displacement distribution from Gaussian form starts in the liquid phase and extends, with increasing magnitude, through the hexatic phase into the crystalline phase. The time for which the deviation is maximum increases exponentially with the density. As the density increases toward the hexatic phase a third dynamical relaxation mode emerges. We argue that the collective motion is generated by superpositions of instantaneous normal mode vibrations, with lifetimes that increase with the density, along paths with strong bond-orientation correlation.

    Title Quorum Sensing-controlled Biofilm Development in Serratia Liquefaciens Mg1.
    Date February 2004
    Journal Journal of Bacteriology
    Excerpt

    Serratia liquefaciens MG1 contains an N-acylhomoserine lactone-mediated quorum-sensing system that is known to regulate swarming motility colonization. In this study, we describe for S. liquefaciens MG1 the development of a novel biofilm consisting of cell aggregates and differentiated cell types, such as cell chains and long filamentous cells. Furthermore, quorum sensing is shown to be crucial for normal biofilm development and for elaborate differentiation. A mutant of S. liquefaciens MG1 that was incapable of synthesizing extracellular signal formed a thin and nonmature biofilm lacking cell aggregates and differentiated cell chains. Signal-based complementation of this mutant resulted in a biofilm with the wild-type architecture. Two quorum-sensing-regulated genes (bsmA and bsmB) involved in biofilm development were identified, and we propose that these genes are engaged in fine-tuning the formation of cell aggregates at a specific point in biofilm development.

    Title High-precision Molecular Wave-packet Interferometry with Hgar Dimers.
    Date January 2004
    Journal Physical Review Letters
    Excerpt

    Molecular wave-packet (WP) interferometry has been demonstrated in the A electronic state of the HgAr van der Waals complex with two time-delayed UV fs pulses at 254 nm. The interferograms of three vibrational levels in the WP's display almost 100% fringe contrast as a function of the interpulse delay tau, which is tuned with sub-10 as stability and resolution. It is clearly observed that the three interferograms show their dephasing and rephasing within a single vibrational period, allowing us to prepare arbitrary relative populations of the three levels by adjusting a single parameter tau.

    Title Effect of Shortened Length of Stay on Functional and Educational Outcome After Pediatric Rehabilitation.
    Date January 2004
    Journal American Journal of Physical Medicine & Rehabilitation / Association of Academic Physiatrists
    Excerpt

    OBJECTIVE: The purpose of this study was to assess changes in the length of stay and its effect on effectiveness and return to school in an inpatient pediatric rehabilitation unit during a 5-yr period from fiscal year 1997 through 2001. DESIGN: We reviewed prospectively collected data for a cohort of 321 children during fiscal years 1997-2001. RESULTS: Length of stay was significantly shortened, with mean lengths of stay of 58.9, 43.5, 30.7, 40.9, and 24.0 days in years 1997 through 2001, respectively. Change in length of stay remained significantly decreased after adjusting for age, sex, admission diagnosis, admission severity, and type of health insurance. There was no difference in mean change in effectiveness measured by change in admission and discharge WeeFIM ratings. There were significant differences across years in the educational placement of children at discharge, with a declining trend in the proportion of children discharged to classroom-based educational services. CONCLUSION: There was a reduction in inpatient length of stay during a 5-yr period for children in this pediatric rehabilitation setting. During this time, there was no change in the effectiveness of rehabilitation as measured by functional outcome. However, using return to a classroom setting as a marker of reintegration into routine activities, fewer children returned to a similar level of community participation.

    Title Temporal Lobe, Autism, and Macrocephaly.
    Date January 2004
    Journal Ajnr. American Journal of Neuroradiology
    Excerpt

    BACKGROUND AND PURPOSE: Because of increased prevalence of macrocephaly in autism, head size must be controlled for in studies that examine volumetric findings of the temporal lobe in autistic subjects. We prospectively examined temporal lobe structures in individuals with autism who were normocephalic or macrocephalic (head circumference > 97th percentile) and in control subjects who were normocephalic or macrocephalic or who had a reading disorder (unselected for head size). The rationale for the reading disorder group was to have control subjects with potential temporal lobe anomalies, but who were not autistic. METHODS: In individuals aged 7-31 years, autism was diagnosed on the basis of standardized interview and diagnostic criteria. Control subjects ranged in age from 7 to 22 years. All subjects were male. MR morphometrics of the major temporal lobe structures were based on ANALYZE segmentation routines, in which total brain volume and total intracranial volume (TICV) were calculated. Both group comparisons and developmental analyses were performed. RESULTS: No distinct temporal lobe abnormalities of volume were observed once head size (TICV) was controlled for. In autistic and control subjects, robust growth patterns were observed in white and gray matter that differed little between the groups. Although subtle differences were observed in some structures (ie, less white matter volume in the region of the temporal stem and overall temporal lobe), none was statistically significant. CONCLUSION: No major volumetric anomalies of the temporal lobe were found in cases of autism when IQ, TICV, and age were controlled. Temporal lobe abnormalities that may be associated with autism are likely to be more related to functional organization within the temporal lobe than to any gross volumetric difference.

    Title Role of White Matter Lesions, Cerebral Atrophy, and Apoe on Cognition in Older Persons with and Without Dementia: the Cache County, Utah, Study of Memory and Aging.
    Date October 2003
    Journal Neuropsychology
    Excerpt

    Neuropsychological, qualitative, and quantitative magnetic resonance imaging findings were examined in subjects with Alzheimer's disease (AD), non-AD dementia or mixed neuropsychiatric disorder, subjects characterized as mild/ambiguous, and controls, all with known apolipoprotein E (APOE) genotype. Neuropsychological tasks included an expanded Consortium to Establish a Registery for Alzheimer's Disease (J. T. Tschanz et al., 2000; K. A. Welsh, J. M. Hoffman, N. L. Earl, & M. W. Hanson 1994) battery and the Mini-Mental Status Examination (M. F. Folstein, S. E. Folstein, & P. R. McHugh, 1975). Periventricular white matter lesions were the most clinically salient, and generalized measures of cerebral atrophy were the most significant quantitative indicators. APOE genotype was unrelated to imaging or neuropsychological performance. Neuropsychological relationships with neuroimaging findings depend on the qualitative or quantitative method used.

    Title Transactivation of a Viral Target Gene by Herpes Simplex Virus Icp27 is Posttranscriptional and Does Not Require the Endogenous Promoter or Polyadenylation Site.
    Date October 2003
    Journal Journal of Virology
    Excerpt

    ICP27 is an essential herpes simplex virus type 1 (HSV-1) immediate-early protein that stimulates viral mRNA expression from many viral delayed-early and late genes during infection. One HSV-1 late gene which is highly dependent on ICP27 during infection is that encoding the glycoprotein C (gC). Here we report that the gC gene is specifically transactivated by ICP27 in transfected Vero cells. Using various gC plasmid constructs, we show that ICP27's stimulatory effects are independent of the gC gene's endogenous promoter and polyadenylation site. This suggests that ICP27-responsive elements lie in the transcribed body of the gC gene. We also show that transactivation of the gC gene by ICP27 is independent of other viral proteins, as ICP27 alone can transactivate the gC gene when its transcription is mediated by the human cytomegalovirus immediate-early gene promoter. However, when gC gene expression is driven by its endogenous promoter, the stimulatory effect of ICP27 requires additional transactivators. To explore the level at which ICP27 transactivates the gC gene, we established stably transfected Vero cell lines that have integrated copies of the gC gene under control of the cytomegalovirus immediate-early gene promoter. These gC genes are not constitutively expressed but can be efficiently induced by HSV-1 infection. Using nuclear run-on transcription assays, we show that transcriptional induction of the stably transfected genes is ICP27 independent. In contrast, accumulation of gC mRNA is very highly dependent on ICP27. Together, these results demonstrate that ICP27 posttranscriptionally activates mRNA expression from a biologically relevant viral target gene.

    Title Signal-mediated Cross-talk Regulates Stress Adaptation in Vibrio Species.
    Date October 2003
    Journal Microbiology (reading, England)
    Excerpt

    Quorum sensing systems serve as a means of 'census taking' of conspecific and non-conspecific bacteria in the near vicinity. The acylated homoserine lactone (AHL) quorum sensing system has been proposed to be primarily an intra-specific communication system, while the AI-2 autoinducer signalling system is proposed to be an interspecific communication system. Here it is shown that AI-2-like signalling in two marine Vibrio species, Vibrio vulnificus and 'Vibrio angustum' S14, induces the core response phenotypes of starvation adaptation and stress resistance, and that a signal antagonist can competitively inhibit these phenotypes. Furthermore, the signals produced by a range of Vibrio species have the ability to induce these phenotypes in V. vulnificus and 'V. angustum' S14, indicating that, at least in Vibrio species, AI-2-like signalling systems function as interspecies communication systems capable of 'cross-talk' and of regulating environmentally relevant phenotypes.

    Title Modification of in Vivo and in Vitro T- and B-cell-mediated Immune Responses by the Pseudomonas Aeruginosa Quorum-sensing Molecule N-(3-oxododecanoyl)-l-homoserine Lactone.
    Date August 2003
    Journal Infection and Immunity
    Excerpt

    N-3-(oxododecanoyl)-L-homoserine lactone (OdDHL), a quorum-sensing molecule of Pseudomonas aeruginosa, plays an important role in the pathogenesis of the organism through its control of virulence factor expression. Several reports have suggested that OdDHL can also directly modulate host immune responses. However, the nature of the modulation is controversial, with different reports suggesting promotion of either humoral (Th2-mediated) or inflammatory (Th1-mediated) responses. This report describes a series of studies which demonstrate for the first time that in vivo administration of OdDHL can modulate the course of an antibody response, with an increase in ovalbumin (OVA)-specific immunogloblulin G1 (IgG1) but not IgG2a in OdDHL-treated OVA-immunized BALB/c mice compared to levels for controls. In vitro stimulation of lymphocytes from both Th1-biased C57Bl/6 and T-cell receptor transgenic mice and Th2-biased BALB/c mice in the presence of OdDHL demonstrated that OdDHL inhibits in vitro cytokine production in response to both mitogen and antigen, with gamma interferon (IFN-gamma) tending to be more inhibited than interleukin-4 (IL-4). In vitro mitogen or antigen restimulation of cells from mice treated with OdDHL in vivo shows effects on cytokine production which depend on the underlying immune bias of the mouse strain used, with a relative increase of IFN-gamma in Th1-biased C57Bl/6 mice and a relative increase of IL-4 in Th2-biased BALB/c mice. Thus, the mode of action of OdDHL on T-cell cytokine production is likely to be a relatively nonspecific one which accentuates an underlying immune response bias rather than one which specifically targets either Th1 or Th2 responses.

    Title The Alternative Sigma Factor Rpon Regulates the Quorum Sensing Gene Rhli in Pseudomonas Aeruginosa.
    Date August 2003
    Journal Fems Microbiology Letters
    Excerpt

    The rhl quorum sensing (QS) circuit of Pseudomonas aeruginosa is known to regulate the expression of a number of virulence factors. This study investigates the regulation of rhlI, encoding the auto-inducer synthase RhlI responsible for the synthesis of N-butryl-L-homoserine lactone (BHL). A putative RpoN binding site was located upstream, in the promoter region of rhlI. Utilising a rhlI-lacZ transcriptional reporter, we demonstrate that under certain media conditions RpoN is a positive regulator of rhlI transcription. Measurements of BHL in extracted supernatant showed that the transcriptional patterns were reflected in the BHL levels, which were reduced in the rpoN mutant. Elastase and pyocyanin, known to be regulated by the rhl QS circuit, were shown to be reduced in a RpoN deficient strain. However, exogenous addition of BHL to the rpoN mutant did not restore these phenotypes suggesting that other regulatory factors apart from BHL are involved. Consistent with other rhl regulated phenotypes, we found that a rpoN mutant strain forms a biofilm that is different from that of the wild-type but similar to that displayed by a rhlI mutant.

    Title Ck2 Protein Kinase is Stimulated and Redistributed by Functional Herpes Simplex Virus Icp27 Protein.
    Date April 2003
    Journal Journal of Virology
    Excerpt

    It has been shown previously (S. Wadd, H. Bryant, O. Filhol, J. E. Scott, T.-T. Hsieh, R. D. Everett, and J. B. Clements, J. Biol. Chem. 274:28991-28998, 2000) that ICP27, an essential and multifunctional herpes simplex virus type 1 (HSV-1) protein, interacts with CK2 and with heterogeneous ribonucleoprotein K (hnRNP K). CK2 is a pleiotropic and ubiquitous protein kinase, and the tetrameric holoenzyme consists of two catalytic alpha or alpha' subunits and two regulatory beta subunits. We show here that HSV-1 infection stimulates CK2 activity. CK2 stimulation occurs at early times after infection and correlates with redistribution of the holoenzyme from the nucleus to the cytoplasm. Both CK2 stimulation and redistribution require expression and cytoplasmic accumulation of ICP27. In HSV-1-infected cells, CK2 phosphorylates ICP27 and affects its cytoplasmic accumulation while it also phosphorylates hnRNP K, which is not ordinarily phosphorylated by this kinase, suggesting an alteration of hnRNP K activities. This is the first example of CK2 stimulation by a viral protein in vivo, and we propose that it might facilitate the HSV-1 lytic cycle by, for example, regulating trafficking of ICP27 protein and/or viral RNAs.

    Title A Partial Copy of Msdna from a New Retron Element is Likely a Retrotransposed Dna Found in the Myxobacterium Nannocystis Exedens.
    Date February 2003
    Journal Gene
    Excerpt

    Retrons are reverse transcriptase (RT) encoding genetic elements usually located on the chromosome of a wide variety of mostly Gram-negative bacteria. Here we describe a new retron, designated Ne144, found in the chromosome of the myxobacterium Nannocystis exedens. This element codes for a 515-amino-acid RT that is most closely related to those found in other myxobacterial retrons. The RT is responsible for the production of a small satellite DNA called msDNA. This msDNA is composed of a 144 base, single-stranded DNA that is linked to a 72 base single-stranded RNA. The RNA strand is joined to the 5' end of the DNA chain via a 2'-5' linkage that occurs from the 2' position of an internal guanosine residue in the RNA. In addition to the retron element, the chromosome of N. exedens also contains several partial copies of the msDNA sequence as revealed by DNA hybridization experiments using msDNA as a probe. One of these partial copies was characterized from a chromosome restriction fragment and found to contain a sequence that matches the last 82 bases of the DNA strand and five bases of the RNA strand in msDNA-Ne144. This partial copy of msDNA is very likely a retrotransposed sequence that was generated by reverse transcription using an RNA (the primer-template RNA for msDNA) as a template and the 3' end of a nick in the chromosome as a primer, followed by incorporation into an open reading frame. The presence of this truncated copy of msDNA is strong evidence of retrotransposition in N. exedens causing an alteration in the bacterial genome.

    Title Defences Against Oxidative Stress During Starvation in Bacteria.
    Date January 2003
    Journal Antonie Van Leeuwenhoek
    Excerpt

    It now seems clear that starvation adaptation is important for cells to initiate long-term survival under conditions of not only nutrient depletion but to develop resistance to other stresses, most notably oxidative stress. Clearly, oxidative stress is a condition likely to be perceived by many bacteria, for example, in the form of reactive oxygen species derived from metabolic processes or from near-UV exposure. We have found evidence for a large degree of overlap in the cell's use of global regulators to deal with both starvation and oxidative stress. Both SpoT and AI-2 signalling pathways are important regulators of starvation and stress adaptation as well as the alternative sigma factor, RpoE. We also present evidence that suggests that AI-2 signalling can mediate starvation adaptation at the molecular level by increasing the stability of the mRNAs so that cells are prepared for rapid response to nutrient addition. Moreover, such extracellular signals mediate intraspecies communication to enable enhanced survival and stress resistance of neighbouring bacterial cells. It is likely that bacteria rely on a suite of effects between cells and on transcription, translation and post-translationalprocesses, mediated by global regulators and signalling molecules, to meet their needs for growth and survival.

    Title Mapping of Functional Regions in the Amino-terminal Portion of the Herpes Simplex Virus Icp27 Regulatory Protein: Importance of the Leucine-rich Nuclear Export Signal and Rgg Box Rna-binding Domain.
    Date December 2002
    Journal Journal of Virology
    Excerpt

    Infected-cell protein 27 (ICP27) is an essential herpes simplex virus type 1 (HSV-1) regulatory protein that activates a subset of viral delayed-early and late genes, at least in part through posttranscriptional mechanisms. Previous studies have shown that the amino (N)-terminal half of the protein contains important functional regions, including a leucine-rich nuclear export signal (NES). However, to date, the phenotype of an HSV-1 ICP27 NES mutant has not been reported. In this study, we engineered and characterized dLeu, an HSV-1 deletion mutant that specifically lacks ICP27's NES (amino acids 6 to 19). The phenotype of dLeu was analyzed alongside those of eight other ICP27 N-terminal deletion mutants. We found that in Vero cells, dLeu displays modest defects in viral gene expression and an approximately 100-fold reduction in the production of viral progeny. Unlike wild-type (WT) ICP27, which exhibits a cytoplasmic distribution in addition to its predominant nuclear localization, dLeu ICP27 is highly restricted to the cell nucleus. This strongly suggests that the N-terminal leucine-rich sequence functions as an NES during viral infection. Our analysis of dLeu and the other mutants has enabled us to genetically define the regions in the N-terminal 200 residues of ICP27 which are required for efficient viral growth in Vero cells. Only two regions appear to be important: (i) the leucine-rich NES and (ii) the RGG box RNA-binding domain, encoded by residues 139 to 153. A virus lacking the RGG box-encoding sequence, d4-5, has a phenotype similar to that of dLeu in that it displays modest defects in viral gene expression and grows poorly. Interestingly, deletion of both the NES and RGG box, as well as the sequences in between, is lethal. The resulting virus, d1-5, displays severe defects in viral gene expression and DNA synthesis and is unable to produce significant amounts of infectious progeny. Therefore, the N-terminal portion of ICP27 contains at least two functional domains which collectively are absolutely essential for viral infection.

    Title Dementia, Asymmetry of Temporal Lobe Structures, and Apolipoprotein E Genotype: Relationships to Cerebral Atrophy and Neuropsychological Impairment.
    Date November 2002
    Journal Journal of the International Neuropsychological Society : Jins
    Excerpt

    We examined asymmetry of hippocampal volume as well as other temporal lobe structures (temporal lobe, temporal horn of the lateral ventricular system, parahippocampal and fusiform gyri) in 194 subjects from the Cache County, Utah study, with varying disorders [85 with Alzheimer's disease (AD), 59 with some cognitive or neuropsychiatric disorder-referenced as a Mixed Neuropsychiatric group, 30 with mild ambiguous/mild cognitive impairment (MA/MCI) and 20 controls] and APOE genotypes. Asymmetry was determined by subtracting left-side volume from the right corrected by total intracranial volume. No significant asymmetry was observed to be associated with presence of the epsilon4 allele. Since the AD-epsilon4 allele risk effect may be expressed early in the course of the disorder, we also examined asymmetry indices in AD, MA/MCI and Mixed Neuropsychiatric subjects early in the course of their disorder (2 years or less) to those with longer duration illness (greater than 2 years). We observed a leftward asymmetry (i.e., left side larger) regardless of APOE genotype in hippocampal volume where both AD and MCI subjects demonstrated a leftward shift in hippocampal size when length of disease (LOD) was less but not more than 2 years. Leftward asymmetry was not associated with LOD in the Mixed Neuropsychiatric group. These findings do not support an association between epsilon4 and hippocampal asymmetry in dementia. We also examined whether asymmetry influenced neuropsychological performance, but minimal effects were observed. Where significance or strong trends were observed, better neuropsychological performance was associated with larger parenchymal volume of temporal lobe structures. These findings were interpreted as representing cognitive reserve effects where larger volume was protective against impairment. The role of asymmetry research in understanding neuropsychological performance in dementia is discussed.

    Title Experimental Observations of Non-gaussian Behavior and Stringlike Cooperative Dynamics in Concentrated Quasi-two-dimensional Colloidal Liquids.
    Date August 2002
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Excerpt

    We report, from direct observation of particle trajectories as a function of time, the presence of stringlike cooperative motion in a quasi-two-dimensional liquid. We have used digital video microscopy to study the equilibrium dynamics of suspensions of sterically stabilized uncharged poly(methylmethacrylate) spheres confined in a thin glass cell. Our experiments reveal the existence, in semidilute and dense liquid states, of a transition in the qualitative dynamical behavior of the system. At short times particles undergo unhindered Brownian motion, at intermediate times they undergo uncorrelated binary collisions, and at long times these one-particle self-diffusive modes are coupled to collective longitudinal acoustic modes of the fluid, the signature of which is local fluctuating domains of enhanced particle mobility. We study the properties of these domains by examining the density dependence of the van Hove self-correlation function and its deviation from Gaussian behavior. We observe that periods of non-Gaussian behavior correlate precisely with the timing of events involved in the relaxation of "caged" particles and their nearest neighbors. In contrast with relaxation processes in supercooled liquids, the lifetime of dynamical heterogeneities in a dissipative colloidal suspension is found to shift towards shorter time scales with increasing particle density. During time periods for which a quasi-two-dimensional system follows Gaussian behavior, we observe that, as predicted by Cichocki and Felderhof [J. Phys. Condens. Matter 6, 7287 (1994)], the time dependence of the evolution of the effective diffusion coefficient from its short time to its long time value has the form (ln t)/t. This last finding is true for all observed particle densities. To our knowledge, these results are the first experimental verification of the existence of microscopic cooperativity and the predicted temporal evolution of the diffusion coefficient for Brownian motion in concentrated quasi-two-dimensional liquids.

    Title Inhibition of Quorum Sensing in Pseudomonas Aeruginosa Biofilm Bacteria by a Halogenated Furanone Compound.
    Date April 2002
    Journal Microbiology (reading, England)
    Excerpt

    Novel molecular tools have been constructed which allow for in situ detection of N-acyl homoserine lactone (AHL)-mediated quorum sensing in Pseudomonas aeruginosa biofilms. The reporter responds to AHL activation of LasR by expression of an unstable version of the green-fluorescent protein (Gfp). Gfp-based reporter technology has been applied for non-destructive, single-cell-level detection of quorum sensing in laboratory-based P. aeruginosa biofilms. It is reported that a synthetic halogenated furanone compound, which is a derivative of the secondary metabolites produced by the Australian macroalga Delisea pulchra, is capable of interfering with AHL-mediated quorum sensing in P. aeruginosa. It is demonstrated that the furanone compound specifically represses expression of a PlasB-gfp reporter fusion without affecting growth or protein synthesis. In addition, it reduces the production of important virulence factors, indicating a general effect on target genes of the las quorum sensing circuit. The furanone was applied to P. aeruginosa biofilms established in biofilm flow chambers. The Gfp-based analysis reveals that the compound penetrates microcolonies and blocks cell signalling and quorum sensing in most biofilm cells. The compound did not affect initial attachment to the abiotic substratum. It does, however, affect the architecture of the biofilm and enhances the process of bacterial detachment, leading to a loss of bacterial biomass from the substratum.

    Title Vibrio Vulnificus: a Physiological and Genetic Approach to the Viable but Nonculturable Response.
    Date March 2002
    Journal Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy
    Excerpt

    In this review, we focus on studies of the viable but nonculturable response (VBNC) of Vibrio vulnificus, a significant and aggressive human pathogen, as a model system for the general understanding of the VBNC response. This response is characterized physiologically as the inability to culture an organism on media that normally supports its growth, and yet those cells retain indicators of metabolic activity. Implicit in this definition is that it may be possible to return or resuscitate VBNC cells to active division on laboratory media. Since its original description in 1985, the VBNC response has been recognized in a range of bacteria. Study of the VBNC response has traditionally focused on physiological methods aimed at demonstrating that VBNC cells are indeed viable but have a specific block that prevents them from dividing on laboratory media, and such study has attempted to identify conditions that unequivocally demonstrate the resuscitation of VBNC cells. With the advent of molecular genetics, VBNC studies have begun to focus on genetics as a means to determine whether there are specific genes or regulatory pathways responsible for the development of the VBNC response. Thus, by combining information from physiological and genetic experiments, it is hoped that it can be determined whether the VBNC response represents a genetically programmed physiological adaptation similar to sporulation and outgrowth or whether VBNC represents the slow loss of function on the way to cellular death.

    Title Interfering for the Good of a Chemical Reaction.
    Date February 2001
    Journal Nature
    Title Smcr-dependent Regulation of Adaptive Phenotypes in Vibrio Vulnificus.
    Date February 2001
    Journal Journal of Bacteriology
    Excerpt

    Vibrio vulnificus contains homologues of the V. harveyi luxR and luxS genes. A null mutation in smcR (luxR) resulted in a defect in starvation survival, inhibition of starvation-induced maintenance of culturability that occurs when V. vulnificus is starved prior to low-temperature incubation, and increased expression of stationary-phase phenotypes.

    Title Accumulation of Herpes Simplex Virus Type 1 Early and Leaky-late Proteins Correlates with Apoptosis Prevention in Infected Human Hep-2 Cells.
    Date January 2001
    Journal Journal of Virology
    Excerpt

    We previously reported that a recombinant ICP27-null virus stimulated, but did not prevent, apoptosis in human HEp-2 cells during infection (M. Aubert and J. A. Blaho, J. Virol. 73:2803-2813, 1999). In the present study, we used a panel of 15 recombinant ICP27 mutant viruses to determine which features of herpes simplex virus type 1 (HSV-1) replication are required for the apoptosis-inhibitory activity. Each virus was defined experimentally as either apoptotic, partially apoptotic, or nonapoptotic based on infected HEp-2 cell morphologies, percentages of infected cells with condensed chromatin, and patterns of specific cellular death factor processing. Viruses d27-1, d1-5, d1-2, M11, M15, M16, n504R, n406R, n263R, and n59R are apoptotic or partially apoptotic in HEp-2 cells and severely defective for growth in Vero cells. Viruses d2-3, d3-4, d4-5, d5-6, and d6-7 are nonapoptotic, demonstrating that ICP27 contains a large amino-terminal region, including its RGG box RNA binding domain, which is not essential for apoptosis prevention. Accumulations of viral TK, VP16, and gD but not gC, ICP22, or ICP4 proteins correlated with prevention of apoptosis during the replication of these viruses. Of the nonapoptotic viruses, d4-5 did not produce gC, indicating that accumulation of true late gene products is not necessary for the prevention process. Analyses of viral DNA synthesis in HEp-2 cells indicated that apoptosis prevention by HSV-1 requires that the infection proceeds to the stage in which viral DNA replication takes place. Infections performed in the presence of the drug phosphonoacetic acid confirmed that the process of viral DNA synthesis and the accumulation of true late (gamma(2)) proteins are not required for apoptosis prevention. Based on our results, we conclude that the accumulation of HSV-1 early (beta) and leaky-late (gamma(1)) proteins correlates with the prevention of apoptosis in infected HEp-2 cells.

    Title Evolution of Poecilogony and the Biogeography of North American Populations of the Polychaete Streblospio.
    Date January 2001
    Journal Evolution; International Journal of Organic Evolution
    Excerpt

    Invertebrate interspecific developmental patterns can be highly variable and, taxonomically, are considered only weakly constrained. Intraspecifically, some invertebrate species possess multiple developmental modes-a condition known as poecilogony. Closer examination of most putative poecilogenous species, however, has not supported poecilogony, but rather has uncovered hidden or cryptic species. The polychaete Streblospio benedicti is a well-known, poecilogenous species found along the coast of North America. We collected mitochondrial cytochrome subunit I DNA sequence data from 88 individuals taken from 11 locations along the Atlantic, Gulf, and Pacific Coasts of the United States to provide a phylogenetic framework from which to interpret intraspecific variation in larval life history and brooding structure morphology in this species. Our results are consistent with a recent revision of the species into two separate species: S. benedicti, a pouched brooding form distributed along the Atlantic and Pacific Coasts, and S. gynobranchiata, a branchiate brooding form in the Gulf of Mexico. Contrary to the redescription, S. benedicti is paraphyletic because the pouched brooding population in Vero Beach, Florida shows strong genetic affinity with Gulf of Mexico populations (S. gynobranchiata). However, S. benedicti is a true poecilogenous species, with both lecithotrophic and planktotrophic individuals possessing identical mitochondrial DNA haplotypes. Crossbreeding experiments further support the molecular phylogeny with reproductive isolation demonstrated between, but not within, the major phylogenetic clades consistent with the previously described species. The genetic break near Vero Beach, Florida, corresponds to a well-known phylogeographic boundary, but the estimated time of separation for the Streblospio spp., approximately 10 million years before present, predates all other known phylogeographic subdivisions in this area. This suggests that biogeographic sundering in this region is a recurrent event. Divergence times within the major Streblospio spp. clades are recent and indicate that changes in larval life history as well as brooding structure morphology are highly plastic and can evolve rapidly.

    Title Bacterial Signals and Antagonists: the Interaction Between Bacteria and Higher Organisms.
    Date September 2000
    Journal Journal of Molecular Microbiology and Biotechnology
    Excerpt

    It is now well established that bacteria communicate through the secretion and uptake of small diffusable molecules. These chemical cues, or signals, are often used by bacteria to coordinate phenotypic expression and this mechanism of regulation presumably provides them with a competitive advantage in their natural environment. Examples of coordinated behaviors of marine bacteria which are regulated by signals include swarming and exoprotease production, which are important for niche colonisation or nutrient acquisition (e.g. protease breakdown of substrate). While the current focus on bacterial signalling centers on N-Acylated homoserine lactones, the quorum sensing signals of gram-negative bacteria, these are not the only types of signals used by bacteria. Indeed, there appears to be many other types of signals produced by bacteria and it also appears that a bacterium may use multiple classes of signals for phenotypic regulation. Recent work in the area of marine microbial ecology has led to the observation that some marine eukaryotes secrete their own signals which compete with the bacterial signals and thus inhibit the expression of bacterial signalling phenotypes. This type of molecular mimicry has been well characterised for the interaction of marine prokaryotes with the red alga, Delisea pulchra.

    Title Processing of Alpha-globin and Icp0 Mrna in Cells Infected with Herpes Simplex Virus Type 1 Icp27 Mutants.
    Date August 2000
    Journal Journal of Virology
    Excerpt

    Herpes simplex virus (HSV) ICP27 is an essential and multifunctional regulator of viral gene expression that modulates RNA splicing, polyadenylation, and nuclear export. We have previously reported that ICP27 causes the cytoplasmic accumulation of unspliced alpha-globin pre-mRNA. Here we examined the effects of a series of ICP27 mutations that alter important functional regions of the protein on the processing and nuclear transport of alpha-globin and HSV ICP0 RNA. The results demonstrate that ICP27 mutants that are impaired for growth in noncomplementing cells, including mutants in the N- and C-terminal regions, are defective in the accumulation of alpha-globin pre-mRNA. Unexpectedly, several mutants that are competent to repress the expression of reporter genes in transient transfection assays failed to accumulate unspliced RNA, implying that different mechanisms are responsible for transrepression and pre-mRNA accumulation. Several mutants caused a marked increase in the length and heterogeneity of the alpha-globin mRNA poly(A) tail, suggesting that ICP27 may directly or indirectly affect the regulation of poly(A) polymerase. ICP27 was also required for the accumulation of multiple ICP0 intron-bearing transcripts, but this effect displayed a mutational sensitivity profile different from that of accumulation of unspliced alpha-globin RNA. Moreover, unlike spliced and unspliced alpha-globin RNAs, which were efficiently exported to the cytoplasm, spliced and intron-containing ICP0 transcripts were predominantly nuclear in localization, and ICP27 was not required for nuclear retention of the spliced message. We propose that these transcript- and ICP27 allele-specific differences may be explained by the presence of a strong cis-acting ICP27 response element in the alpha-globin transcript.

    Title The Conserved Carboxyl-terminal Half of Herpes Simplex Virus Type 1 Regulatory Protein Icp27 is Dispensable for Viral Growth in the Presence of Compensatory Mutations.
    Date August 2000
    Journal Journal of Virology
    Excerpt

    ICP27 is an essential herpes simplex virus type 1 (HSV-1) immediate-early protein that regulates viral gene expression by poorly characterized mechanisms. Previous data suggest that its carboxyl (C)-terminal portion is absolutely required for productive viral infection. In this study, we isolated M16R, a second-site revertant of a viral ICP27 C-terminal mutant. M16R harbors an intragenic reversion, as demonstrated by the fact that its cloned ICP27 allele can complement the growth of an HSV-1 ICP27 deletion mutant. DNA sequencing demonstrated that the intragenic reversion is a frameshift alteration in a homopolymeric run of C residues at codons 215 to 217. This results in the predicted expression of a truncated, 289-residue molecule bearing 72 novel C-terminal residues derived from the +1 reading frame. Consistent with this, M16R expresses an ICP27-related molecule of the predicted size in the nuclei of infected cells. Transfection-based viral complementation assays confirmed that the truncated, frameshifted protein can partially substitute for ICP27 in the context of viral infection. Surprisingly, its novel C-terminal residues are required for this activity. To see if the frameshift mutation is all that is required for M16R's viability, we re-engineered the M16R ICP27 allele and inserted it into a new viral background, creating the HSV-1 mutant M16exC. An additional mutant, exCd305, was constructed which possesses the frameshift in the context of an ICP27 gene with the C terminus deleted. We found that both M16exC and exCd305 are nonviable in Vero cells, suggesting that one or more extragenic mutations are also required for the viability of M16R. Consistent with this interpretation, we isolated two viable derivatives of exCd305 which grow productively in Vero cells despite being incapable of encoding the C-terminal portion of ICP27. Studies of viral DNA synthesis in mutant-infected cells indicated that the truncated, frameshifted ICP27 protein can enhance viral DNA replication. In summary, our results demonstrate that the C-terminal portion of ICP27, conserved widely in herpesviruses and previously believed to be absolutely essential, is dispensable for HSV-1 lytic replication in the presence of compensatory genomic mutations.

    Title The Marine Pathogen Vibrio Vulnificus Encodes a Putative Homologue of the Vibrio Harveyi Regulatory Gene, Luxr: a Genetic and Phylogenetic Comparison.
    Date July 2000
    Journal Gene
    Excerpt

    Vibrio vulnificus is an opportunistic pathogen that exhibits numerous virulence factors, including the secretion of a zinc metalloprotease and the production of a capsule. We have cloned and sequenced a gene from V. vulnificus that is a homologue of the positive transcriptional regulator, luxR, of the lux operon in Vibrio harveyi. This gene encodes a putative, single complete open reading frame designated smcR, which shares greater than 75% nucleotide identity with luxR of V. harveyi. The deduced amino acid sequence of the putative SmcR protein is more than 90% identical and 95% similar to that of LuxR of V. harveyi, suggesting that V. vulnificus possesses a member of the family of signal-response genes recently described in Vibrio cholerae and in Vibrio parahaemolyticus. Our data also demonstrate that, in addition to V. vulnificus, all six Vibrio spp. tested contained genes that hybridized with the luxR probe. We also present evidence that this regulatory protein was inherited from a common ancestor, and that the gene is ancient and widespread in marine Vibrio spp.

    Title Inhibition of Luminescence and Virulence in the Black Tiger Prawn (penaeus Monodon) Pathogen Vibrio Harveyi by Intercellular Signal Antagonists.
    Date June 2000
    Journal Applied and Environmental Microbiology
    Excerpt

    Expression of luminescence in the Penaeus monodon pathogen Vibrio harveyi is regulated by an intercellular quorum sensing mechanism involving the synthesis and detection of two signaling molecules, one of which is N-hydroxy butanoyl-L-homoserine lactone and the other of which is uncharacterized. Indirect evidence has suggested that virulence, associated with a toxic extracellular protein, and luminescence in V. harveyi are coregulated. In this study the effects of an acylated homoserine lactone antagonist produced by the marine alga Delisea pulchra on luminescence and toxin production in a virulent strain of V. harveyi were analyzed. Luminescence and toxin production were both inhibited by the signal antagonist at concentrations that had no impact on growth. Toxin production was found to be prematurely induced in V. harveyi cultures incubated in a 10% conditioned medium. Additionally, a significant reduction in the toxicity of concentrated supernatant extracts from V. harveyi cultures incubated in the presence of the signal antagonist, as measured by in vivo toxicity assays in mice and prawns, was observed. These results suggest that intercellular signaling antagonists have potential utility in the control of V. harveyi prawn infections.

    Title Icp22 and the Ul13 Protein Kinase Are Both Required for Herpes Simplex Virus-induced Modification of the Large Subunit of Rna Polymerase Ii.
    Date July 1999
    Journal Journal of Virology
    Excerpt

    Herpes simplex virus type 1 (HSV-1) infection alters the phosphorylation of the large subunit of RNA polymerase II (RNAP II), resulting in the depletion of the hypophosphorylated and hyperphosphorylated forms of this polypeptide (known as IIa and IIo, respectively) and induction of a novel, alternatively phosphorylated form (designated IIi). We previously showed that the HSV-1 immediate-early protein ICP22 is involved in this phenomenon, since induction of IIi and depletion of IIa are deficient in cells infected with 22/n199, an HSV-1 ICP22 nonsense mutant (S. A. Rice, M. C. Long, V. Lam, P. A. Schaffer, and C. A. Spencer, J. Virol. 69:5550-5559, 1995). However, depletion of IIo still occurs in 22/n199-infected cells. This suggests either that another viral gene product affects the RNAP II large subunit or that the truncated ICP22 polypeptide encoded by 22/n199 retains residual activity which leads to IIo depletion. To distinguish between these possibilities, we engineered an HSV-1 ICP22 null mutant, d22-lacZ, and compared it to 22/n199. The two mutants are indistinguishable in their effects on the RNAP II large subunit, suggesting that an additional viral gene product is involved in altering RNAP II. Two candidates are UL13, a protein kinase which has been implicated in ICP22 phosphorylation, and the virion host shutoff (Vhs) factor, the expression of which is positively regulated by ICP22 and UL13. To test whether UL13 is involved, a UL13-deficient viral mutant, d13-lacZ, was engineered. This mutant was defective in IIi induction and IIa depletion, displaying a phenotype very similar to that of d22-lacZ. In contrast, a Vhs mutant had effects that were indistinguishable from wild-type HSV-1. Therefore, UL13 but not the Vhs function plays a role in modifying the RNAP II large subunit. To study the potential role of UL13 in viral transcription, we carried out nuclear run-on transcription analyses in infected human embryonic lung cells. Infections with either UL13 or ICP22 mutants led to significantly reduced amounts of viral genome transcription at late times after infection. Together, our results suggest that ICP22 and UL13 are involved in a common pathway that alters RNAP II phosphorylation and that in some cell lines this change promotes viral late transcription.

    Title Urease and Hexadecylamine-urease Films at the Air-water Interface: an X-ray Reflection and Grazing Incidence X-ray Diffraction Study.
    Date June 1999
    Journal Biophysical Journal
    Excerpt

    We report the results of surface x-ray scattering measurements performed on urease and hexadecylamine-urease films at the air-aqueous solution interface. It is demonstrated that although hexadecylamine does not form a stable monolayer on the pure aqueous surface, it does self-assemble into a stable, well-organized structure when spread on top of a urease film at the air-water interface. It is also likely that protein and hexadecylamine domains coexist at the interface.

    Title Protein Folding at the Air-water Interface Studied with X-ray Reflectivity.
    Date May 1999
    Journal Proceedings of the National Academy of Sciences of the United States of America
    Excerpt

    We report the results of x-ray reflectivity measurements of thin films formed by different water-soluble proteins at the air-aqueous solution interface. It is demonstrated that glucose oxidase, alcohol dehydrogenase, and urease molecules denaturate at the air-aqueous solution interface to form 8- to 14-A-thick peptide sheets. X-ray reflectivity data indicate that the spreading of a lipid monolayer at the aqueous solution surface before protein injection does not prevent proteins from unfolding. On the other hand, crosslinking of proteins results in intact enzyme layers at the subphase surface. A model that involves interaction of glucose oxidase molecules with a phospholipid monolayer is proposed. In this model, an observed decrease of the lipid electron density in the protein presence is explained in terms of "holes" in the monolayer film caused by protein molecule adsorption.

    Title The Herpes Simplex Virus Immediate-early Protein Icp27 Shuttles Between Nucleus and Cytoplasm.
    Date April 1998
    Journal Virology
    Excerpt

    ICP27 is an essential herpes simplex virus type 1 (HSV-1) nuclear protein which regulates viral early and late genes during infection. The exact mechanism by which ICP27 modulates viral gene expression is unknown, but considerable evidence suggests that it functions posttranscriptionally. In this study, we have asked whether ICP27, like some other viral and cellular posttranscriptional regulatory proteins, shuttles between the nuclear and cytoplasmic compartments of the cell. Using an interspecies heterokaryon assay, we demonstrate that ICP27, but not the HSV-1 nuclear proteins ICP4 or ICP8, is an efficient shuttling protein. ICP27's shuttling ability does not depend on viral infection or other HSV-1 proteins, as it shuttles even when transiently expressed in uninfected cells. To understand the importance of shuttling for ICP27's regulatory functions, we examined several mutant forms of ICP27 to see whether they exhibited altered shuttling. We identified three ICP27 mutations which partially disrupt shuttling, as well as one mutation, M15, which completely abrogates this activity. The M15 mutation alters residues 465 and 466 near the carboxyl terminus of ICP27 and was previously shown to inactivate ICP27's ability to induce certain viral late mRNAs. These results suggest that ICP27's nuclear shuttling activity is involved in its viral late gene activation function.

    Title Pediatric Morning Report: an Appraisal.
    Date December 1997
    Journal Clinical Pediatrics
    Excerpt

    We examined and contrasted morning reports at two hospitals, university and community, that have a pediatric residency program. Patient diagnoses assigned at morning report were compared with final diagnoses to assess disease categories discussed and the value of including outpatient follow-up in this educational forum. Data were obtained during morning reports for 6 months by chief residents at university and private community hospitals. Pertinent history, physical examination, and laboratory and radiologic findings were recorded and were assigned a tentative morning report diagnosis based on morning report discussion. Cases were then reviewed at discharge and at 6 months to determine final diagnoses. At the university hospital, 58% of the cases were undiagnosed before presentation at morning report. Of those cases, 23% were assigned a diagnosis at morning report that differed from the final diagnosis. Similarly, at the private community hospital, 28% of cases were undiagnosed before presentation at morning report. Of those cases, 73% were assigned a diagnosis that differed from the final diagnosis. We conclude that the provision of follow-up at morning report is important for maximizing resident education.

    Title Repetitive Sequences Found in the Chromosome of the Myxobacterium Nannocystis Exedens Are Similar to Msdna: a Possible Retrotransposition Event in Bacteria.
    Date May 1997
    Journal Molecular Microbiology
    Excerpt

    The first reverse transcriptase (RT) to be found in a prokaryotic cell is encoded by an element called a retron which resides in the chromosome of many different bacteria. In addition, all retrons code for a functionally obscure RNA-DNA satellite molecule called msDNA. msDNA is synthesized from an RNA template by the retron-encoded RT. An unusual retron element is described here from the myxobacterium Nannocystis exedens. This retron does not appear to have a typical RT gene in close proximity (1 kb) to the gene msd (which encodes the DNA strand of msDNA). The gene msr (which encodes the RNA strand of msDNA) appears to be duplicated and flanks both sides of the msd gene. Also discovered throughout the chromosome of this bacterium is a set of repeated sequences related to msDNA. These repeat sequences match only part of the sequences of msDNA and may have become incorporated into the chromosome of this bacterium by reverse transcription.

    Title Repression of Host Rna Polymerase Ii Transcription by Herpes Simplex Virus Type 1.
    Date March 1997
    Journal Journal of Virology
    Excerpt

    Lytic infection of mammalian cells with herpes simplex virus type 1 (HSV-1) results in rapid repression of host gene expression and selective activation of the viral genome. This transformation in gene expression is thought to involve repression of host transcription and diversion of the host RNA polymerase (RNAP II) transcription machinery to the viral genome. However, the extent of virus-induced host transcription repression and the mechanisms responsible for these major shifts in transcription specificities have not been examined. To determine how HSV-1 accomplishes repression of host RNAP II transcription, we assayed transcription patterns on several cellular genes in cells infected with mutant and wild-type HSV-1. Our results suggest that HSV-1 represses RNAP II transcription on most cellular genes. However, each cellular gene we examined responds differently to the transcription repressive effects of virus infection, both quantitatively and with respect to the involvement of viral gene products. Virus-induced shutoff of host RNAP II transcription requires expression of multiple immediate-early genes. In contrast, expression of delayed-early and late genes and viral DNA replication appear to contribute little to repression of host cell RNAP II transcription. Modification of RNAP II to the intermediately phosphorylated (II(I)) form appears unlinked to virus-induced repression of host cell transcription. However, full repression of host transcription is correlated with depletion of the hyperphosphorylated (IIO) form of RNAP II.

    Title The Rgg Box Motif of the Herpes Simplex Virus Icp27 Protein Mediates an Rna-binding Activity and Determines in Vivo Methylation.
    Date December 1996
    Journal Journal of Virology
    Excerpt

    ICP27 is an essential herpes simplex virus type 1 nuclear regulatory protein that is required for efficient viral gene expression. Although the mechanism by which ICP27 regulates genes is unknown, a variety of evidence suggests that it functions posttranscriptionally, and recent studies indicate that it is an RNA-binding protein. Previously, we noted that a short arginine- and glycine-rich sequence in ICP27 (residues 138 to 152) is similar to an RGG box motif, a putative RNA-binding determinant found in a number of cellular proteins (W. Mears, V. Lam, and S. Rice, J. Virol. 69:935-947, 1995). In the present study, we have further investigated ICP27's association with RNA and examined the role of the RGG box in RNA binding. We find that ICP27 binds efficiently to RNA homopolymers composed of poly(G) and weakly to poly(U) RNA homopolymers. Poly(G) binding activity maps to the N-terminal 189 residues of ICP27 and requires the RGG box sequence. Using a northwestern blotting assay, we demonstrate that the RGG box alone (residues 140 to 152) can mediate RNA binding when attached to a heterologous protein. As many cellular RGG box proteins are methylated on arginine residues, we also investigated the in vivo methylation status of ICP27. Our results demonstrate that ICP27 is methylated in herpes simplex virus-infected cells. Methylation is dependent on the presence of the RGG box, suggesting that one or more arginine residues in the RGG box sequence are modified. These data demonstrate that ICP27 displays the characteristics of an RGG box-type RNA-binding protein.

    Title Attenuation of Dna-dependent Protein Kinase Activity and Its Catalytic Subunit by the Herpes Simplex Virus Type 1 Transactivator Icp0.
    Date December 1996
    Journal Journal of Virology
    Excerpt

    The DNA-dependent protein kinase (DNA-PK) is involved in several fundamental nuclear processes, including DNA double-strand break repair, V(D)J recombination, and transcription by RNA polymerases I and II. In this study, we show that infection of mammalian cells with herpes simplex virus type 1 attenuates DNA-PK activity by specifically depleting the p350/DNA-PKcs catalytic subunit. The half-life of the p350/DNA-PKcs protein decreases from greater than 24 h to less than 4 h following infection. The depletion of DNA-PK activity and p350/DNA-PKcs abundance is dependent on expression of the viral immediate-early protein ICP0. As ICP0 acts as a promoter-independent transactivator of gene expression, these data suggest that ICP0 may function by directly or indirectly targeting the p350/DNA-PKcs subunit of DNA-PK, thereby altering the inhibitory effects of DNA-PK on RNA polymerase II transcription.

    Title Bacterial Reverse Transcriptase and Msdna.
    Date December 1996
    Journal Virus Genes
    Excerpt

    Retrons are a new class of genetic elements found in the chromosome of a large number of different bacteria. These elements code for a reverse transcriptase (RT) that is structurally similar to the polymerases of retroviruses. The retron associated RT is responsible for the production of an unusual extrachromosomal satellite DNA, known as multicopy, single-stranded DNA (msDNA). Synthesis of msDNA is dependent on a novel self-priming mechanism, resulting in the formation of a 2',5'-phosphodiester bond. A comparison of bacterial RTs is presented, noting conserved and unique features of these polymerases. In addition, the origin, means of dissemination, and possible activities of these functionally obscure retroelements are discussed.

    Title Neonatal Group B Streptococcal Vertebral Osteomyelitis.
    Date October 1996
    Journal Pediatrics
    Title Herpes Simplex Virus Immediate-early Protein Icp22 is Required for Viral Modification of Host Rna Polymerase Ii and Establishment of the Normal Viral Transcription Program.
    Date September 1995
    Journal Journal of Virology
    Excerpt

    Infection of cells with herpes simplex virus type 1 (HSV-1) results in a rapid alteration of phosphorylation on the large subunit of cellular RNA polymerase II (RNAP II), most likely on its C-terminal domain (S. A. Rice, M. C. Long, V. Lam, C. A. Spencer, J. Virol. 68:988-1001, 1994). This phosphorylation modification generates a novel form of the large subunit which we have designed IIi. In this study, we examine roles that HSV-1 gene products play in this process. An HSV-1 mutant defective in the immediate-early transcriptional activator protein ICP4 is able to efficiently induce IIi. Viruses having mutations in the genes for the ICP0, ICP6, or ICP27 proteins are also competent for IIi formation. In contrast, 22/n199, an HSV-1 mutant which contains a nonsense mutation in the gene encoding the immediate-early protein ICP22, is significantly deficient in IIi induction. This effect is seen in Vero cells, where 22/n199 grows relatively efficiently, and in human embryonic lung (HEL) cells, where 22/n199 growth in more restricted. RNAP II is recruited into viral replication compartments in 22/n199-infected cells, indicating that altered phosphorylation of RNAP II is not a prerequisite for nuclear relocalization of RNAP II. In addition, we show by nuclear run-on transcription analysis that viral gene transcription is deficient in HEL cells infected with 22/n199. Viral late gene transcription does not occur efficiently, and antisense transcription throughout the genome is diminished compared with that of the wild-type HSV-1 infection. These transcriptional effects cannot be explained by differences in viral DNA replication, since 22/n199 replicates its DNA efficiently in HEL cells. Our results demonstrated that ICP22 is necessary for virus-induced aberrant phosphorylation of RNAP II and for normal patterns of viral gene transcription in certain cell lines.

    Title Trimethoprim-sulfamethoxazole-associated Central Nervous System Disease.
    Date May 1995
    Journal The Pediatric Infectious Disease Journal
    Title Identification of Nuclear and Nucleolar Localization Signals in the Herpes Simplex Virus Regulatory Protein Icp27.
    Date February 1995
    Journal Journal of Virology
    Excerpt

    Previous work has shown that the herpes simplex virus type 1 (HSV-1) regulatory protein ICP27 localizes to the cell nucleus and that certain mutant ICP27 polypeptides localize preferentially in nucleoli. To map the signals in ICP27 which mediate its nuclear localization, we identified the portions of ICP27 which can direct a cytoplasmic protein, pyruvate kinase (PK), to nuclei. Our results demonstrate that ICP27 contains multiple nuclear localization signals (NLSs) that function with differing efficiencies. First, ICP27 possesses a strong NLS, mapping to residues 110 to 137, which bears similarity to the bipartite NLSs found in Xenopus laevis nucleoplasmin and other proteins. Second, ICP27 possesses one or more weak NLSs which map to a carboxyl-terminal portion of the protein between residues 140 and 512. Our PK-targeting experiments also demonstrate that ICP27 contains a relatively short sequence, mapping to residues 110 to 152, that can function as a nucleolar localization signal (NuLS). This signal includes ICP27's strong NLS as well as 15 contiguous residues which consist entirely of arginine and glycine. This latter sequence is very similar to an RGG box, a putative RNA-binding motif found in a number of cellular proteins which are involved in nuclear RNA processing. To confirm the results of the PK-targeting experiments, we mutated the ICP27 gene by deleting sequences encoding either the strong NLS or the RGG box. Deletion of the strong NLS (residues 109 to 138) resulted in an ICP27 molecule that was only partially defective for nuclear localization, while deletion of the RGG box (residues 139 to 153) resulted in a molecule that was nuclear localized but excluded from nucleoli. Recombinant HSV-1s bearing either of these deletions were unable to replicate efficiently in Vero cells, suggesting that ICP27's strong NLS and RGG box carry out important in vivo functions.

    Title Phylogenetic Comparison of Retron Elements Among the Myxobacteria: Evidence for Vertical Inheritance.
    Date January 1995
    Journal Journal of Bacteriology
    Excerpt

    Twenty-eight myxobacterial strains, representing members from all three subgroups, were screened for the presence of retron elements, which are novel prokaryotic retroelements encoding reverse transcriptase. The presence of retrons was determined by assaying strains for a small satellite DNA produced by reverse transcription called multicopy, single-stranded DNA (msDNA). An msDNA-producing retron appeared to be absent from only one of the strains surveyed. DNA hybridization experiments revealed that retron elements similar to retron Mx162, first identified in Myxococcus xanthus, were found only among members of the Myxococcus subgroup; that is, each of the seven different genera which constitute this subgroup contained a Mx162 homolog. Another retron element also appeared to have a clustered distribution, being found exclusively within the Nannocystis subgroup of the myxobacteria. A retron element of the Mx162 type was cloned from Melittangium lichenicola, and its DNA sequence was compared with those of similar elements in M. xanthus and Stigmatella aurantiaca. Together, the degree of sequence diversity, the codon bias of the reverse transcriptase genes, and the clustered distribution of these retrons suggest a possible evolutionary scenario in which a common ancestor of the Myxococcus subgroup may have acquired this retroelement.

    Title A Poxvirus Protein with a Ring Finger Motif Binds Zinc and Localizes in Virus Factories.
    Date July 1994
    Journal Journal of Virology
    Excerpt

    Shope fibroma virus (SFV) is a Leporipoxvirus closely related to the highly virulent myxoma virus. The DNA sequence of the BamHI N fragment of the SFV DNA genome was determined, and the single complete open reading frame (N1R) was characterized. The protein encoded by the N1R gene was found to contain a C3HC4 RING finger motif at the C terminus. This C3HC4 motif is the hallmark of a growing family of proteins, many of which are involved in regulation of gene expression, DNA repair, or DNA recombination. Complete homologs of the SFV N1R gene were also detected in variola virus, myxoma virus, and vaccinia virus strain IHD-W. In contrast, the gene is completely absent from vaccinia virus strain Copenhagen, and in vaccinia virus strain WR, the open reading frame is truncated prior to the zinc binding domain because of an 11-bp deletion, thus producing a frameshift and premature stop codon. Recombinant N1R protein from SFV was expressed in Escherichia coli and shown to bind zinc in a specific manner. Using fluorescence microscopy to visualize a peptide epitope tag (derived from ICP27 of herpes simplex virus) fused to the N terminus of the poxvirus proteins, we observed that the N1R protein of SFV and its homologs in myxoma virus and vaccinia virus IHD-W were localized primarily to the virus factories in the cytoplasm of infected cells and, to a lesser degree, the host cell nucleus. The truncated protein of vaccinia virus strain WR failed to localize in this manner but instead was observed throughout the cytoplasm.

    Title Ul69 of Human Cytomegalovirus, an Open Reading Frame with Homology to Icp27 of Herpes Simplex Virus, Encodes a Transactivator of Gene Expression.
    Date June 1994
    Journal Journal of Virology
    Excerpt

    The UL69 open reading frame of human cytomegalovirus (HCMV) is homologous to the immediate-early protein ICP27 of herpes simplex virus, an essential viral regulatory protein involved in the transition from early to late gene expression. Genes with homology to ICP27 have been detected in all subclasses of herpesviruses so far. While the respective proteins in alpha- and gammaherpesviruses have been defined as trans-regulatory molecules, nothing is known about these genes in betaherpesviruses. This study was therefore undertaken in order to investigate expression from the UL69 gene locus of HCMV. Northern (RNA) blot experiments revealed a complex pattern of transcripts that changed during the time course of the HCMV replicative cycle: two transcripts of 2.7 and 3.5 kb that were regulated differentially could be detected as early as 7 h after infection. However, these transcripts could not be detected in the presence of cycloheximide. Additional, larger transcripts were present exclusively at late times after infection. To analyze protein expression from the UL69 gene region, the UL69 open reading frame was expressed as a histidine-tagged protein in Escherichia coli. A specific antiserum was generated and used to detect the UL69 protein in HCMV-infected cells which revealed its localization within the intranuclear inclusions that are characteristic for HCMV infection. In cotransfection experiments, an HCMV true late promoter could not be activated by UL69, whereas an early promoter and several heterologous promoters were stimulated about 10-fold. Complementation studies showed that the UL69 protein cannot substitute for ICP27 in the context of the HSV infection, suggesting functional differences between these two proteins. In summary, these experiments define a novel regulatory protein encoded by HCMV that is expressed as an early-late gene and appears to exert a broad stimulatory effect on gene expression.

    Title Amino Acid Substitution Mutations in the Herpes Simplex Virus Icp27 Protein Define an Essential Gene Regulation Function.
    Date February 1994
    Journal Journal of Virology
    Excerpt

    ICP27 is an essential herpes simplex virus type 1 (HSV-1) alpha protein that is required for the transition from the beta to the gamma phase of infection. To identify functional regions of ICP27, we constructed 16 plasmids that contain nucleotide substitution mutations in the ICP27 gene. The mutations created XhoI restriction sites, altered one or two codons, and were spaced at semiregular intervals throughout the coding region. Three mutations completely inactivated an essential function of ICP27, as demonstrated by the inability of the transfected plasmids to complement the growth of an HSV-1 ICP27 deletion mutant. These mutations, M11, M15, and M16, mapped in the carboxyl-terminal one-third of ICP27 at residues 340 and 341, 465 and 466, and 488, respectively. In cotransfection assays, all three defective-plasmid mutants retained the transrepression function of ICP27 but were defective at transactivation. To define the lytic functions that are mediated by the transactivation activity of ICP27, we engineered HSV-1 recombinants containing the M11, M15, or M16 mutation. All three viral mutants failed to grow in Vero cells and possessed similar phenotypes. The viral mutants replicated their DNA similarly to the wild-type virus but showed several defects in viral gene expression. These were a failure to down-regulate alpha and beta genes at late times after infection and an inability to induce certain gamma-2 genes. Our results demonstrate that the transactivation function of ICP27 (as it is defined in cotransfection assays) mediates an essential gene regulation function during the HSV-1 infection. This activity is not required for ICP27-dependent enhancement of viral DNA replication. Our work supports and extends previous studies which suggest that ICP27 carries out two distinct regulatory activities during the HSV-1 infection.

    Title Rna Polymerase Ii is Aberrantly Phosphorylated and Localized to Viral Replication Compartments Following Herpes Simplex Virus Infection.
    Date February 1994
    Journal Journal of Virology
    Excerpt

    During lytic infection, herpes simplex virus subverts the host cell RNA polymerase II transcription machinery to efficiently express its own genome while repressing the expression of most cellular genes. The mechanism by which RNA polymerase II is directed to the viral delayed-early and late genes is still unresolved. We report here that RNA polymerase II is preferentially localized to viral replication compartments early after infection with herpes simplex virus type 1. Concurrent with recruitment of RNA polymerase II into viral compartments is a rapid and aberrant phosphorylation of the large subunit carboxy-terminal domain (CTD). Aberrant phosphorylation of the CTD requires early viral gene expression but is not dependent on viral DNA replication or on the formation of viral replication compartments. Localization of RNA polymerase II and modifications to the CTD may be instrumental in favoring transcription of viral genes and repressing specific transcription of cellular genes.

    Title Fever and Skin Lesions in a Five-year-old Boy.
    Date February 1994
    Journal The Pediatric Infectious Disease Journal
    Title Diversity of Retron Elements in a Population of Rhizobia and Other Gram-negative Bacteria.
    Date July 1993
    Journal Journal of Bacteriology
    Excerpt

    Genetic elements called retrons reside on the chromosome of Escherichia coli and the myxobacteria and represent the first reverse transcriptase-encoding element to be found in a prokaryotic cell. All known retrons produce a functionally obscure RNA-DNA satellite molecule called multicopy single-stranded DNA (msDNA). We report here the presence of msDNA-producing retron elements in a number of new bacterial groups, including strains of the genera Proteus, Klebsiella, Salmonella, Nannocystis, Rhizobium, and Bradyrhizobium. Among a population of 63 rhizobia strains, only 16% contain a retron element. The rhizobia retrons appear to be heterogeneous in nucleotide sequence and show little similarity to previously studied retrons of E. coli and the myxobacteria.

    Title The Clinical Spectrum of Patients with Aneurysms of the Ascending Aorta.
    Date May 1993
    Journal American Heart Journal
    Excerpt

    Aneurysms of the ascending aorta are often unsuspected, yet they can quickly lead to death from aortic rupture or dissection. To examine the clinical spectrum of patients with aneurysms of the ascending aorta, we searched the University of California, San Francisco (USCF) Echocardiography Data Base for all patients with aneurysms of the ascending aorta (> or = 5.0 cm in diameter) seen over a 7-year period. The echocardiograms and clinical courses of these patients were then reviewed. We identified 15 patients with aneurysms of the ascending aorta: five had aneurysms > 7.0 cm in diameter, three had aneurysms 6.0 to 6.9 cm, and seven had aneurysms 5.0 to 5.9 cm in diameter. Among the five patients < 50 years of age, four had Marfan's syndrome, and among the 10 patients > or = 50 years of age, eight had evidence of atherosclerotic vascular disease. At presentation, 13 patients had nonspecific symptoms, and two were asymptomatic. Echocardiography demonstrated that 12 patients had at least mild aortic insufficiency and that five had aortic dissections. One of the seven patients who underwent surgical resection died of an intraoperative cardiac arrest, and two of the eight patients treated medically died within 1 week of presentation. We conclude that the clinical spectrum of patients with aneurysms of the ascending aorta is wide. Because these aneurysms are often unsuspected, physicians should have a low threshold for imaging the ascending aorta in patients with Marfan's syndrome or atherosclerotic vascular disease, particularly when aortic insufficiency is present.

    Title Prolonged Administration of Isoflurane to Pediatric Patients During Mechanical Ventilation.
    Date April 1993
    Journal Anesthesia and Analgesia
    Excerpt

    We undertook a prospective study of the effectiveness and potential toxicities of isoflurane sedation in pediatric patients undergoing mechanical ventilation who required large doses of opioids for sedation were considered eligible. Ten patients (ages 3 wk to 19 yr) received continuous isoflurane sedation for a mean duration of 131 minimum alveolar concentration (MAC)-hours (range 13-497 MAC-hours). The mean peak inorganic fluoride (F-) concentration was 11.0 microM, and the highest F- concentration was 26.1 microM after 441 MAC-hours. Only one patient had a measured F- concentration greater than 20 microM. No abnormalities were noted in serum creatinine or osmolality. Creatinine clearances were available for five patients who received a mean of 193 MAC-hours of isoflurane (range 33-497 MAC-hours), and only one patient had a persistent decrease from baseline of more than 20%. Five patients demonstrated an abstinence syndrome which consisted of nonpurposeful movements and extreme agitation. All of these patients had received at least 70 MAC-hours of isoflurane. Our experience indicates that isoflurane can effectively provide sedation to pediatric patients for prolonged periods without significant adverse effects on cardiovascular, hepatic, or renal function.

    Title The Acidic Amino-terminal Region of Herpes Simplex Virus Type 1 Alpha Protein Icp27 is Required for an Essential Lytic Function.
    Date April 1993
    Journal Journal of Virology
    Excerpt

    The herpes simplex virus type 1 (HSV-1) alpha protein ICP27 regulates the transition between the delayed-early and late phases of the viral infection. Previous genetic analyses have suggested that the important functional domains of ICP27 map to its carboxyl-terminal half. One striking feature of the primary sequence of ICP27, however, is an extremely acidic region near its amino terminus. To determine whether this region is required for ICP27 function, we deleted the sequences in the ICP27 gene which encode it (codons 12 through 63). In transient expression assays, the deletion mutant was unable to efficiently repress the expression of a cotransfected reporter gene or to efficiently complement the growth of d27-1, an HSV-1 ICP27 null mutant. These results suggested that the acidic region of ICP27 is involved in a regulatory function required for lytic growth. To test this possibility further, we introduced the mutant allele into the HSV-1 genome by marker transfer. Two independently derived isolates of the mutant virus, designated d1-2a and d1-2b, were recovered and analyzed. Both isolates were defective for growth in Vero cells, exhibiting a 100-fold reduction in virus yield compared with the wild-type infection. Vero cells infected with the d1-2 isolates showed a three- to eightfold reduction in viral DNA replication, a moderate reduction in the expression of viral gamma genes, and a delay in the repression of beta genes. The phenotype of the d1-2 isolates differs substantially from the phenotypes of previously isolated ICP27 mutants, which show much more severe defects in viral gene expression. Our results demonstrate that the amino-terminal half of ICP27 participates in its regulatory activities in both infected and transfected cells.

    Title Effects of Thiourea Tolerance on Plasma Histamine, and Lung Vascular Permeability.
    Date March 1992
    Journal Archives of Toxicology
    Excerpt

    Adult male rats treated with a lethal edematogenic dose of thiourea (TU) (10.0 mg/kg, intraperitoneally) responded with significant elevations in plasma histamine, lung vascular permeability and 100% mortality over a subsequent 24-h period. When rats were pretreated with a small non-lethal dose of TU (0.5 mg/kg) and subsequently challenged with the lethal dose at 1, 4, 8, 16 and 32 days later, there was complete protection against death for at least 8 days and partial protection for an additional 24 days. This decrease in mortality correlated quite closely with reduced plasma histamine levels and diminished pulmonary vascular permeability. The results suggest that reduced exposure of the pulmonary vasculature to histamine may offer a partial explanation for tolerance to thiocarbamide compounds in the rat.

    Title Longitudinal Distribution of Pulmonary Vascular Resistance After Endotoxin Administration in Sheep.
    Date February 1992
    Journal Critical Care Medicine
    Excerpt

    BACKGROUND AND METHODS: Pulmonary hypertension may increase pulmonary capillary pressure and exacerbate pulmonary edema in acute respiratory failure. The effects of pulmonary hypertension on pulmonary capillary pressure depend on the longitudinal distribution of pulmonary vascular resistance. Since pulmonary hypertension occurs during acute respiratory failure, we hypothesized that acute respiratory failure may produce time-dependent changes in the longitudinal distribution of pulmonary vascular resistance. Therefore, we measured pulmonary capillary pressure and the longitudinal distribution of pulmonary vascular resistance in an animal model of acute respiratory failure. Escherichia coli endotoxin (2.5 to 5.0 micrograms/kg) was administered over a 1-hr period in eight anesthetized sheep. Pulmonary and systemic hemodynamics, including pulmonary artery occlusion pressure (PAOP), pulmonary capillary pressure, and the longitudinal distribution of pulmonary vascular resistance, were measured over the next 5 hrs. Pulmonary capillary pressure was estimated by analysis of the pressure decay following pulmonary artery balloon inflation. RESULTS: Endotoxin administration resulted in sustained pulmonary hypertension for the subsequent 5 hrs of the study. Pulmonary capillary pressure was increased 7 mm Hg above baseline at 0.5 and 0.75 hrs during the infusion of endotoxin but returned to baseline values at 1.5 hrs. Despite sustained pulmonary hypertension, pulmonary capillary pressure remained at baseline values for the duration of the study. Similar to pulmonary capillary pressure, pulmonary venous (or postcapillary) resistance was increased approximately four-fold over baseline at 0.5 and 0.75 hrs after initiating endotoxin administration, but returned to baseline values by the end of endotoxin administration and remained at baseline values throughout the remainder of the study. In contrast, pulmonary arterial (or precapillary) resistance remained at values approximately three times baseline during the infusion and throughout the duration of the study. CONCLUSIONS: In this experimental model of acute respiratory failure, the effects of endotoxin on the longitudinal distribution of pulmonary vascular resistance are time-dependent. If these data from animals can be extrapolated to humans, we speculate that the importance of pulmonary venoconstriction in exacerbating pulmonary edema may vary over time in patients with acute respiratory failure.

    Title Effects of Thiourea on Pulmonary Vascular Permeability and on Lung and Plasma Histamine Levels in Rats.
    Date September 1991
    Journal Toxicology Letters
    Excerpt

    The intraperitoneal administration of thiourea (TU) to mature male rats results in a significant increase in lung vascular permeability to Evans Blue dye (EBD). On the other hand, young, sexually immature rats are resistant to this effect. The increase in lung vascular permeability in response to TU in mature rats is associated with corresponding increases in lung and plasma histamine levels. The correlation of increases in lung and plasma histamine in response to TU is similar to that reported for ammonium salts which produce similar pulmonary edema.

    Title Effect of Prenatal N2o Exposure on Startle Reflex Reactivity.
    Date January 1991
    Journal Teratology
    Excerpt

    The teratogenic effect of N2O is of interest because thousands of pregnant women are exposed to this gaseous anesthetic each year. The effects of repeated N2O exposures were investigated for offspring of mice exposed to air or N2O (5%, 15%, or 35%) for 4 hours per day on days 6 through 15 of pregnancy. Ten litters per exposure group were studied. Exposures did not affect reproductive indices, survival, or physical milestones of development. Body weights showed significant exposure effects that could not be isolated to specific exposure groups; however, N2O-exposed mice tended to weigh more than air-exposed animals. Brain weights measured on postnatal day (PND) 126 or 127 were not different among exposure groups or between genders. Ability to stay on a rotating rod was not affected by prenatal N2O exposure. Prenatal exposure to N2O resulted in hyporeactivity of the startle reflex in response to acoustic or tactile stimuli. On PND 95 the results were statistically significant for all N2O-exposed groups compared with the air-exposed group. On PND 60, although not statistically significant, there was a definite trend toward hyporeactivity for the N2O groups. There was a significant age-related difference in startle response; control animals were significantly more reactive at 95 than at 60 days of age. Of the N2O-exposed groups, only the 15% group showed a statistically significant increase in reactivity from 60 to 95 days of age. The risk of behavioral or functional abnormalities for humans following in utero N2O exposure is unknown and cannot be directly extrapolated from the present study.(ABSTRACT TRUNCATED AT 250 WORDS)

    Title Propylene-glycol-induced Pulmonary Hypertension in Sheep.
    Date June 1990
    Journal Pharmacology
    Excerpt

    Propylene glycol is commonly used as a vehicle for drug administration. In experiments involving the measurement of pulmonary hemodynamics, pentobarbital anesthesia routinely resulted in pulmonary hypertension in sheep. Since pentobarbital is formulated with 40% propylene glycol, we studied the pulmonary hemodynamic effects of propylene glycol in halothane-anesthetized sheep. Intravenous 40% propylene glycol (0.12 ml/kg over 3 min) rapidly increased pulmonary artery pressure (from 10 +/- 2 to 18 +/- 1 mm Hg; p less than 0.01) and pulmonary vascular resistance (from 200 +/- 18 to 500 +/- 51 dyn.s.cm-5; p less than 0.01); pulmonary hypertension was still present 1 h later. In sheep pretreated with the selective thromboxane A2 synthesis inhibitor dazmegrel, propylene glycol did not affect pulmonary artery pressure or pulmonary vascular resistance. Propylene-glycol-induced pulmonary hypertension in sheep appears to be mediated by thromboxane A2. Both ethanol and polyethylene glycol similarly produce pulmonary hypertension in sheep. We conclude that vehicle control data are required for studies using propylene glycol in sheep and advise caution when propylene glycol is employed as a vehicle in clinical use.

    Title Genetic Evidence for Two Distinct Transactivation Functions of the Herpes Simplex Virus Alpha Protein Icp27.
    Date May 1990
    Journal Journal of Virology
    Excerpt

    Infected-cell protein 27 (ICP27) is a herpes simplex virus type 1 alpha, or immediate-early, protein involved in the regulation of viral gene expression. To better understand the function(s) of ICP27 in infected cells, we have isolated and characterized viral recombinants containing defined alterations in the ICP27 gene. The mutant virus d27-1 contains a 1.6-kilobase deletion which removes the ICP27 gene promoter and most of the coding sequences, while n59R, n263R, n406R, and n504R are mutants containing nonsense mutations which encode ICP27 molecules truncated at their carboxyl termini. All five mutants were defective for lytic replication in Vero cells. Analysis of the mutant phenotypes suggests that ICP27 has the following regulatory effects during the viral infection: (i) stimulation of expression of gamma-1 genes, (ii) induction of expression of gamma-2 genes, (iii) down regulation of expression of alpha and beta genes late in infection, and (iv) stimulation of viral DNA replication. Cells infected with the mutant n504R expressed wild-type levels of gamma-1 proteins but appeared to be unable to efficiently express gamma-2 mRNAs or proteins. This result suggests that ICP27 mediates two distinct transactivation functions, one which stimulates gamma-1 gene expression and a second one required for gamma-2 gene induction. Analysis of the mutant n406R suggested that a truncated ICP27 polypeptide can interfere with the expression of many viral beta genes. Our results demonstrate that ICP27 has a variety of positive and negative effects on the expression of viral genes during infection.

    Title Inorganic Fluoride and Prolonged Isoflurane Anesthesia in the Intensive Care Unit.
    Date January 1990
    Journal Anesthesia and Analgesia
    Title In Vitro Hepatic Drug and Anesthetic Metabolism of Rats with Dietary-induced Obesity.
    Date October 1989
    Journal Archives Internationales De Pharmacodynamie Et De Thérapie
    Excerpt

    The mechanism for enhanced metabolism of inhaled anesthetics in obese rats and humans is unknown. In this study, hepatic microsomes from normal-weight chow-fed rats and rats fed a high fat diet for approximately 54 weeks to induce obesity were examined for their ability to metabolize fluorinated inhalation anesthetics. Body composition of rats on diet for 54 weeks revealed a significantly elevated lipid content of both the whole body and liver in obese compared to normal-weight rats. Protein per g liver was not significantly different. The hepatic microsomal content of cytochromes b5 and P-450 per mg protein was not different between obese and normal-weight rats. Hepatic microsomal defluorination rates of the anesthetics, methoxyflurane, enflurane and isoflurane, were not altered by high fat diets of 54 weeks duration. The activity rate of aminopyrine N-demethylase was not changed by the diet; however, p-nitroanisole O-demethylase activity was significantly increased in microsomes from obese rats to approximately 150% of control activity. Thus the enhanced in vivo anesthetic metabolism of obese Fischer 344 rats does not appear to be the result of an increase in the specific activity of anesthetic metabolizing enzymes.

    Title Metabolism of Halothane in Obese Fischer 344 Rats.
    Date October 1989
    Journal Anesthesiology
    Excerpt

    Halothane is metabolized by an oxidative pathway to stable, nonvolatile end products, trifluoroacetic acid (TFAA) and bromide (Br-), and by reductive pathways to Br-and inorganic fluoride (F-). There is evidence that both oxidatively and reductively formed intermediates may produce hepatotoxicity, although the exact etiology of the fulminant hepatic necrosis seen in humans is unproven. Obese patients receiving volatile anesthetics exhibit higher serum anesthetic metabolite concentrations than do normal-weight patients, and thus might be at greater risk of hepatotoxicity because of higher concentrations of reactive intermediates from halothane metabolism. To eliminate the variables inherent in human clinical studies leading to confounding interpretation of data, this study determined the contributions of oxidative and reductive pathways to halothane metabolism in an animal model of human hypertrophic obesity, the most common form of human obesity. Eight pairs of obese (high-fat diet) and normal-weight (standard chow), male Fischer 344 rats were anesthetized with halothane for 4 h at an inspired concentration of 0.78%. Serum and urinary concentrations of TFAA, Br-, and F-were measured. Thirty-six hours following halothane anesthesia, mean serum TFAA concentrations peaked at 7.3 +/- 1.1 mM in obese rats and 4.7 +/- 0.7 mM in nonobese rats. TFAA urinary excretions during the 180-h period postanesthesia were 519 +/- 69 and 336 +/- 22 mumol, respectively. Peak serum Br- concentrations were 9.1 +/- 1.0 and 6.9 +/- 0.6 mM for obese and nonobese rats, respectively, and Br-urinary excretions were 127 +/- 30 and 79 +/- 14 mumol, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

    Title Herpes Simplex Virus Alpha Protein Icp27 Possesses Separable Positive and Negative Regulatory Activities.
    Date August 1989
    Journal Journal of Virology
    Excerpt

    The HSV-1 alpha (immediate-early) protein ICP27 expressed in transfected cells can activate the expression of certain HSV-1 promoters as well as inhibit the transactivated expression of others. We constructed a set of plasmids encoding mutant ICP27 molecules truncated at their carboxyl termini and used transfection assays to determine the functional properties of the mutant proteins. A polypeptide containing the amino-terminal 263 amino acid residues of ICP27 retained partial ability to activate gene expression but was unable to inhibit transactivation. Mutant proteins possessing 406 or 504 amino acids of ICP27 were unable to activate gene expression but retained full ability to inhibit transactivation. These results define two separable regulatory activities of ICP27, one positive and one negative, which can modulate gene expression in transfected cells. Immunoblot and immunofluorescence experiments were used to study the immunological reactivities and intracellular localizations of the mutant proteins. All proteins possessing the amino-terminal 263 amino acids of ICP27 reacted with an ICP27-specific monoclonal antibody and were localized to the cell nucleus. The mutant proteins, however, exhibited a number of phenotypes with regard to intranuclear localization. A mutant possessing 504 residues of ICP27 was similar to the wild-type protein in apparently localizing to all regions of the nucleus. A mutant containing 406 residues of ICP27, on the other hand, was mostly excluded from the nucleolar regions, while a 263-residue mutant was localized predominantly in the nucleoli. Thus, some aspect of ICP27 structure or function can dramatically affect its intranuclear distribution.

    Title Gene-specific Transactivation by Herpes Simplex Virus Type 1 Alpha Protein Icp27.
    Date October 1988
    Journal Journal of Virology
    Excerpt

    Herpes simplex virus type 1 (HSV-1) encodes several alpha (immediate-early) gene products that modulate gene expression during viral replication. We report here that the alpha protein ICP27 specifically stimulates expression of a later viral gene, that encoding glycoprotein B (gB). Using temperature-sensitive viral mutants, the effect of ICP27 on HSV-1 protein synthesis was examined at early times after infection or at later times when viral DNA replication was inhibited. Under these conditions, the expression of gB showed a marked dependence on the presence of functional ICP27, whereas several other beta and gamma 1 genes showed a lesser dependence. It was also noted that cells infected with ICP27 temperature sensitive mutants at the nonpermissive temperature showed a reduction in the electrophoretic mobility of the alpha protein ICP4. To examine the mechanism by which ICP27 stimulated gB expression, a plasmid was constructed in which the promoter-regulatory region of the gB gene was fused to the gene encoding chloramphenicol acetyltransferase (CAT). CAT expression from this plasmid was induced significantly by ICP27 expressed from a cotransfected plasmid. Induction of CAT activity by ICP27 correlated well with an increase in the amount of CAT transcripts initiated from the transcriptional start site of the gB gene. The transactivating activity of ICP27 was specific for the gB promoter-regulatory region, as expression from several other HSV-1 promoter-CAT chimeric genes was not stimulated by ICP27. The DNA sequences which conferred the response to ICP27 mapped within 175 base pairs upstream and 41 base pairs downstream of the gB transcriptional start site. Our results suggest that the full expression of gB and perhaps other viral genes during HSV-1 infection requires the combined action of multiple viral transactivators.

    Title Alternative Mechanisms for Activation of Human Immunodeficiency Virus Enhancer in T Cells.
    Date April 1988
    Journal Science (new York, N.y.)
    Excerpt

    The expression of human immunodeficiency virus (HIV) after T cell activation is regulated by NF-kappa B, an inducible DNA-binding protein that stimulates transcription. Proteins encoded by a variety of DNA viruses are also able to activate expression from the HIV enhancer. To determine how this activation occurs, specific genes from herpes simplex virus type 1 and adenovirus that activate HIV in T lymphoma cells have been identified. The cis-acting regulatory sequences in the HIV enhancer that mediate their effect have also been characterized. The relevant genes are those for ICP0-an immediate-early product of herpes simplex virus type 1-and the form of E1A encoded by the 13S messenger RNA of adenovirus. Activation of HIV by adenovirus E1A was found to depend on the TATA box, whereas herpesvirus ICP0 did not work through a single defined cis-acting element. These findings suggest multiple pathways that can be used to bypass normal cellular activation of HIV, and they raise the possibility that infection by herpes simplex virus or adenovirus may directly contribute to the activation of HIV in acquired immunodeficiency syndrome by mechanisms independent of antigenic stimulation in T cells.

    Title Contrasting Effects of Etomidate and Propylene Glycol Upon Enflurane Metabolism and Adrenal Steroidogenesis in Fischer 344 Rats.
    Date March 1988
    Journal Anesthesiology
    Excerpt

    This study was designed to investigate the effects of etomidate and its solubilizing agent (propylene glycol) upon enflurane metabolism and adrenal steroidogenesis in Fischer 344 rats. A central venous catheter was placed using pentobarbital anesthesia, and rats were randomized to one of four groups for treatment several days later. Group 1 animals received normal saline, 3 ml/kg, given via the central venous catheter. The other three groups were administered equivalent volumes of either: crystalline etomidate (group 2), 0.4 mg/ml, in saline and 1.1% ethanol; propylene glycol (group 3), 7%, in saline; or etomidate (group 4), 0.4 mg/ml in saline with 7% propylene glycol. In the first part of this study, after an intravenous bolus of one of these four solutions, animals were immediately placed in a 200-liter chamber and received 1 h of 2% enflurane. Serum and urine were assayed for inorganic fluoride (F-) before and after anesthesia. Two hours after enflurane anesthesia, groups 1 and 2 had the highest mean peak serum F- concentrations (13.2 and 13.5 uM, respectively). Groups 3 and 4 had significantly lower mean peak serum F- concentrations (4.7 and 4.5 uM, respectively). In the second part of this study, additional animals were randomized into four groups and received the same intravenous medications as above. Thirty minutes later, they received an intravenous bolus of ACTH. Blood samples were drawn and serum aldosterone levels were measured. Animals in groups 1 and 3 had significantly greater increases in peak serum aldosterone levels 30 minutes after ACTH (peak levels: 0.80 and 0.77 ng/ml, respectively) than animals in groups 2 and 4 (peak levels: 0.60 and 0.58 ng/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

    Title The Behavioral Effects of Perinatal Methimazole Administration in Swiss Webster Mice.
    Date August 1987
    Journal Fundamental and Applied Toxicology : Official Journal of the Society of Toxicology
    Excerpt

    Methimazole was tested for use as a positive control agent in behavioral studies of mice. Continuous administration of the antithyroid agent via drinking water (0.1 mg/ml) from Day 16 of pregnancy through Day 10 postpartum produced developmental delays in mice offspring. Ten methimazole and 12 untreated litters were studied. Developmental milestones were unaltered; i.e., time of pinna detachment, incisor eruption, eye opening, vaginal patency, and testicular descent were not different between groups. Mean body weights of methimazole offspring were consistently reduced, but significant differences were isolated to a few days in the preweaning period and a few weeks during the postweaning period. There was no enduring effect. All preweaning tests showed some significant treatment-related changes; methimazole pups were developmentally delayed. Surface righting time was increased while time pivoting and the number of quadrants traveled were decreased in methimazole pups. Negative geotaxis showed significant treatment-related increases in the time to orient 180 degrees uphill, the percentage of pups orienting 180 degrees uphill, and the percentage of pups orienting less than 180 degrees. Ontogeny of swimming ability also showed significant delays. The only postweaning test evaluated, time on a rotating rod, showed no treatment-related effects. Brain weights Postnatal Day (PND) 120 were not different between groups. In this study, methimazole produced developmental delays in mice that were detectable by behavioral tests. Thus, methimazole has potential as a positive control agent for mice, not only to validate preweaning test sensitivity, but also to validate a laboratory's ability to perform preweaning behavioral studies.

    Title Halothane Hepatotoxicity in Fischer 344 Rats Pretreated with Isoniazid.
    Date April 1987
    Journal Toxicology and Applied Pharmacology
    Excerpt

    Male Fischer 344 rats were used to investigate the hepatic effects of exposure to halothane under normoxic conditions (FIO2 = 0.21) in isoniazid-treated rats. Animals were treated with saline or isoniazid (50 mg/kg) for 7 days and then were exposed to either 1% halothane or air for 2 hr. One-half of the rats from each treatment and exposure group were killed 24 hr postexposure; the remaining were killed 4 days postexposure. Twenty-four hours following halothane exposure, serum transaminase levels were significantly elevated in isoniazid- compared with saline-treated rats (i.e., aspartate aminotransferase = twofold; alanine aminotransferase = seven-fold). Cholesterol levels were significantly depressed by halothane exposure in both saline- and isoniazid-treated rats. Other serum parameters indicative of hepatic and renal function were not different: alkaline phosphatase, total protein, total bilirubin, hematocrit, uric acid, creatinine, urea nitrogen, Na+, K+, Ca2+, and inorganic phosphate. Neither saline-treated nor isoniazid-treated rats exposed to air exhibited histologic evidence of hepatic damage. Halothane-exposed rats, however, showed a circumscribed disruption of cellular morphology. The most severe lesions were observed with isoniazid-treated animals with extensive pericentral hepatocellular necrosis and infiltration by leucocytes and Kupffer cells. Serum concentrations of two products of the oxidative metabolism of halothane, trifluoroacetic acid and bromide, were significantly elevated in isoniazid- compared with saline-treated rats. Serum levels of fluoride, a product of reductive metabolism, were not different. These results strongly suggest that hepatic injury following halothane administration can be produced by intermediates of oxidative metabolism.

    Title Multiple Effects of the 72-kda, Adenovirus-specified Dna Binding Protein on the Efficiency of Cellular Transformation.
    Date March 1987
    Journal Virology
    Excerpt

    The early region 2A gene (E2A) of adenovirus types 2 and 5 encodes a 72-kDa DNA binding protein (DBP) which contains two physical domains comprising approximately the amino-terminal one-third and carboxyl-terminal two-thirds of the protein, respectively. Previous work has shown that some Ad5 mutants containing temperature-sensitive (ts) mutations in the carboxyl-terminal domain of DBP, such as Ad5ts125, show a 3- to 8-fold enhanced ability to transform rat cells. We have examined the transformation characteristics of a series of Ad5 E2A deletion mutants, Ad5dl801-5, which encode either no functional DBP or encode truncated, defective DBPs. The E2A deletion mutants transformed rat embryo cells at frequencies similar to wild-type (wt) Ad5. These results suggest that the high transformation phenotype of carboxyl-terminal E2A mutants like Ad5ts125 is not due to the simple inactivation of DBP function, but rather results from an activity possessed by an altered DBP. This hypothesis is supported by the fact that the transformation phenotype of Adsts125 and similar mutants is dominant over the wild-type phenotype. A number of additional Ad2 and Ad5 E2A mutants were examined with respect to their ability to transform primary rat embryo cells. It was found that a carboxyl-terminal E2A mutant, Ad2+ND1ts23, also showed the enhanced transformation phenotype. In contrast, several amino-terminal E2A host-range (hr) mutants, originally isolated on the basis of their ability to replicate in monkey cells, transformed rat embryo cells at a frequency similar to wild-type virus. Ad2ts400, and E2A mutant with alterations in both DBP domains, showed a wild-type frequency of transformation, while two similar mutants, Ad5ts125 X 405 and Ad5ts125 X 404, showed an enhanced frequency. Last, it was found that coinfection of primary rat embryo cells with the hr mutants plus Ad5ts125 or Ad2+ND1ts23 resulted in a wild-type frequency of transformation, demonstrating that the hr mutants are dominant to the ts mutants with regard to transformation phenotype. Thus, DBP can both positively and negatively affect viral transformation in this system.

    Title Stages in the Nuclear Association of the Herpes Simplex Virus Transcriptional Activator Protein Icp4.
    Date March 1987
    Journal Journal of Virology
    Excerpt

    The nuclear localization of the herpes simplex virus transcriptional activator protein ICP4 was studied by indirect immunofluorescence. At early times after viral infection, ICP4 quickly localized to a diffuse intranuclear distribution. ICP4 later concentrated in globular compartments within the nucleus. The redistribution to the compartments was dependent on viral DNA replication. Double staining for ICP4 and ICP8, the early major DNA-binding protein, revealed that both were found in the same intranuclear globular compartments at late times. These were previously named "replication compartments" (M. P. Quinlan, L. B. Chen, and D. M. Knipe, Cell 36:857-868, 1984). Because ICP4 and ICP8 are known to function in transcriptional activation and DNA replication, respectively, both DNA replication and late transcription may occur in these compartments. The association of ICP4 and ICP8 with the replication compartments appeared to be independent in that the retention of ICP8 in the compartments required ongoing viral DNA synthesis, while the association of ICP4 was independent of viral DNA synthesis once the compartments were formed. Because ICP4 shows a different distribution at early and late times, stimulation of transcription by ICP4 may involve different molecular events or contacts during these two periods of the replicative cycle.

    Title Effect of Diazepam Treatment on Hepatic Microsomal Anesthetic Defluorinase Activity.
    Date January 1987
    Journal Archives Internationales De Pharmacodynamie Et De Thérapie
    Excerpt

    Different dosing regimens with diazepam were evaluated in male Fischer 344 rats for their ability to enhance the metabolism of several inhalation anesthetics. In vitro metabolism was assessed by the rate of microsomal anesthetic defluorination as measured by the appearance of inorganic fluoride ion (i.e., defluorinase activity). Single daily doses of diazepam, 40 mg/kg, were delivered by gavage for either 7 or 14 days; more continuous dosing was achieved by administration of diazepam at 0.03% or 0.10% in food pellets. Hepatic microsomes isolated from treated rats showed significant dose-related elevations in methoxyflurane defluorinase activity, but not in enflurane or isoflurane defluorinase activities. The microsomal content of cytochromes P-450 and b5 and the NADPH-cytochrome-c-reductase activity was not significantly different among treated and untreated groups. Para-nitroanisole O-demethylase activity expressed per nmole cytochrome P-450 increased in the diazepam-treated groups. Extrapolation of these animal data to humans suggests that surgical patients treated chronically with diazepam are probably not at increased risk for inorganic fluoride-induced nephrotoxicity due to increased metabolism of the fluorinated inhalation anesthetics.

    Title Purification and Identification of Rat Hepatic Cytosolic Enzymes Responsible for Defluorination of Methoxyflurane and Fluoroacetate.
    Date September 1986
    Journal Drug Metabolism and Disposition: the Biological Fate of Chemicals
    Excerpt

    Enzymes responsible for the defluorination of methoxyflurane (MOF) and fluoroacetate (FAc) were separated and purified from rat liver cytosol. Both hepatic cytosolic enzymes with defluorination activity were labile and addition of 2-mercaptoethanol had little effect on the stability of these enzymes. Glutathione S-transferase (GT) activity of the same cytosolic fractions was stable for at least 11 days. Separation of defluorination and GT enzymatic activities on DEAE-Sephadex A-50 and reduced glutathione-affinity columns revealed that the defluorinations of MOF and FAc were primarily catalyzed by anionic proteins which also exhibited GT activity. Further identification by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed protein bands with pl values of approximately 6.5 and 6.9 and molecular weights of approximately 20,000. However, other proteins that exhibited no GT activity also defluorinated MOF and FAc, but accounted for only 10% of the total defluorination activity present in anionic proteins. Results from a separate purification experiment using a CM-cellulose column also indicated that the enzymes responsible for defluorination coeluted with cationic GTs. Collectively, these cationic enzymes were responsible for about 20% of the recovered cytosolic defluorination activities. The results suggest that the cytosolic defluorinations of both MOF and FAc are primarily the result of a dehalogenation reaction catalyzed by one or more species of rat liver cytosolic GTs.

    Title Anesthetic Metabolism and Renal Function in Obese and Nonobese Fischer 344 Rats Following Enflurane or Isoflurane Anesthesia.
    Date July 1986
    Journal Anesthesiology
    Excerpt

    This study was designed to determine the nephrotoxic potential of prolonged anesthesia with enflurane or isoflurane in obese and nonobese Fischer 344 rats. Weight-paired rats received either a regular chow diet or Potter's high fat diet for 16 weeks. The chow-fed (nonobese) rats gained 20% in body weight compared with 45% for the Potter's-fed (obese) rats. Exposure of nine pairs of rats to 2.0% enflurane for 4 h resulted in significantly elevated peak serum F-levels (62 +/- 11 microM vs. 27 +/- 6 microM; P less than 0.001) in obese compared with nonobese rats and clinical signs of F(-)-induced nephrotoxicity (i.e., polyuria) confirmed by decreased creatinine and urea nitrogen clearances in the obese rats. Exposure of nine pairs of rats to 1.4% isoflurane for 4 h produced significantly elevated peak serum F-levels (27 +/- 8 microM vs. 9 +/- 0.4 microM; P less than 0.001) in obese compared with nonobese rats and subclinical nephrotoxicity in obese rats manifested by significantly decreased creatinine and urea nitrogen clearances, but without polyuria. This study suggest that obese patients may be at risk of developing F(-)-induced nephrotoxicity following prolonged enflurane anesthesia. Isoflurane may have significant potential for subclinical F(-)-induced nephrotoxicity in obese patients, to a degree that might affect renal clearance of some drugs in the postoperative period.

    Title Effects of Subchronic Intermittent Exposure to Isoflurane in Swiss Webster Mice.
    Date July 1986
    Journal Journal of Environmental Pathology, Toxicology and Oncology : Official Organ of the International Society for Environmental Toxicology and Cancer
    Excerpt

    Swiss Webster mice were treated to determine if subchronic intermittent exposure to the inhalation anesthetic isoflurane causes organ toxicity or enhances its own metabolism or that of other anesthetics. One-hundred twenty, four-week-old male and female mice were exposed to compressed air or to 0.02%, 0.1% or 0.5% of isoflurane for four hours per day, five days per week for nine weeks. Body weights among the groups were the same prior to exposure. Overall, there were no significant differences in body weights among exposure groups (ANOVA with day as a repeated measure: females - F = 2.12, P = 0.1085; males - F = 1.80, P = 0.1583). There was, however, a significant interaction of group and days; differences were isolated to the start of exposure (weeks 1 through 3 for females; week 2 for males). At all times, differences remained within 10% of the control body weights. Organ weights (liver, spleen, kidney, testis and uterus), hematocrits, and SGOT levels were similar among exposure groups. Histologic evaluation of organs revealed no anesthetic-related organ toxicity. The concentration of hepatic cytochromes, b5 and P-450, per mg of microsomal protein were similar among exposure groups and between sexes. The rates of hepatic microsomal metabolism (defluorination) of three volatile halogenated ether anesthetics (methoxyflurane, enflurane, and isoflurane) were not different among groups following nine weeks of exposure. Isoflurane exposures of 0.5% or less for four hours per day for five days per week would appear to be the maximum tolerated concentration for any chronic study. Since there was no evidence of organ toxicity or of enhanced or inhibited hepatic microsomal enzyme activity, isoflurane seems to be relatively non-toxic inhalation anesthetic under the conditions of this study.

    Title Validation of a Developmental Swimming Test Using Swiss Webster Mice Perinatally Treated with Methimazole.
    Date June 1986
    Journal Neurobehavioral Toxicology and Teratology
    Excerpt

    The swimming method of Klaus and Hacker, developed for the AB/Jena and DBA2/Jena mouse strains, was evaluated for use with pre-weaned Swiss Webster (SW) mice. All SW mice completed the swimming pattern by postnatal day (PND) 16, but did not conform to all criteria depicted for each stage of the methodology. These swimming differences among strains required modification of the above method for the SW mouse. An expanded and revised swimming methodology included evaluation of limb movement and placement; body position; head position, including nostril and ear positions; and direction of movement. The revised methodology was validated on PND 4 through 20 with offspring of methimazole-treated or untreated SW dams. Methimazole, an antithyroid agent, was administered in drinking water (0.1 mg/ml; day 16 of pregnancy through day 10 postpartum). Untreated dams received tap water. Methimazole pups exhibited significant delays in swimming development on PND 9 through 16. This revised swimming methodology provides another preweaning test for the detection of behavioral teratogens for SW and probably other strains of mice.

    Title Biotransformation of Halothane and Enflurane in Patients with Hyperthyroidism.
    Date March 1986
    Journal Anesthesiology
    Title Reproductive and Teratogenic Effects of Nitrous Oxide, Halothane, Isoflurane, and Enflurane in Sprague-dawley Rats.
    Date March 1986
    Journal Anesthesiology
    Excerpt

    A total of 305 timed-pregnant Sprague-Dawley rats were exposed for 6 h a day on each of three consecutive days in one of three periods, i.e., pregnancy days 14-16, 11-13, or 8-10, either to 0.55 times the minimum alveolar concentration (MAC) of nitrous oxide (75%) or to 0.75 MAC of halothane (0.8%), isoflurane (1.05%) or enflurane (1.65%); an additional 232 positive-control (retinoic acid) and air control rats were studied. Reproductive indices were determined, and the 5178 offspring delivered at cesarean section were examined for external, internal, and skeletal abnormalities. There were no major or minor teratologic effects in anesthetic treated groups, although several developmental variants were observed in halothane- and enflurane-treated groups. Nitrous oxide exposure on days 14-16 resulted in a three-fold increase in fetal resorptions. The results suggest that the volatile anesthetics are not teratogenic and confirm that nitrous oxide may be associated with increased reproductive loss.

    Title Fetal Development in Mice Exposed to Isoflurane.
    Date February 1986
    Journal Teratology
    Excerpt

    The developmental toxicity of trace (0.006%), subanesthetic (0.06%), and light anesthetic (0.6%) exposure to isoflurane was examined in Swiss/Webster mice. No adverse effects were demonstrated following exposure of dams to 0.006% (n = 26) and 0.06% (n = 27) isoflurane for 4 hr daily on days 6-15 of pregnancy. Exposure to 0.6% isoflurane (n = 23) for the same period resulted in significantly decreased fetal weight, decreased skeletal ossification, minor hydronephrosis, and increased renal pelvic cavitation. The incidence of cleft palate also was significantly increased, abnormalities occurring in 12.1% of fetuses and affecting 11 of 23 litters. This incidence was considerably higher than that of the combined treatment and colony control groups (0.75%) and those that we have found in previous experiments with this mouse strain following exposure to halothane (1.2%) or enflurane (1.9%).

    Title Effects of Subchronic Intermittent Exposure to Nitrous Oxide in Swiss Webster Mice.
    Date January 1986
    Journal Journal of Environmental Pathology, Toxicology and Oncology : Official Organ of the International Society for Environmental Toxicology and Cancer
    Excerpt

    Swiss Webster mice were treated to determine whether the inhalational anesthetic, nitrous oxide (N2O), causes organ toxicity and enhances anesthetic defluorination. Two-hundred and sixteen young adult male and female mice were exposed to room air or to 5,000 (.5%), 50,000 (5%) or 500,000 (50%) N2O for four hours per day, five days per week for periods up to fourteen weeks. Body weight was measured twice weekly throughout the experiment. Liver, kidney, spleen and testis were weighed and examined histologically along with brain, stomach, seminal vesicle, and ovary for evidence of drug induced damage. Blood smears were examined microscopically and complete blood count, differential white cell count, and reticulocyte and platelet counts were performed. In addition, liver microsomal cytochrome P-450 content and the rates of defluorination of enflurane and methoxyflurane were determined. The maximum tolerated concentration of N2O was approximately 5000,000 ppm. Even at this high dose, there was no evidence of organ damage. Following N2O exposure, neither the hepatic microsomal cytochrome P-450 content nor the rates of anesthetic defluorination were increased; the rate of in vitro inorganic fluoride production was greater for methoxyflurane than for enflurane. Since there was no evidence of specific organ toxicity or of enzyme induction or inhibition, it was concluded that N2O is a comparatively nontoxic inhalational anesthetic under the conditions of this study.

    Title Isolation and Analysis of Adenovirus Type 5 Mutants Containing Deletions in the Gene Encoding the Dna-binding Protein.
    Date January 1986
    Journal Journal of Virology
    Excerpt

    A genetic system is described which allows the isolation and propagation of adenovirus mutants containing lesions in early region 2A (E2A), the gene encoding the multifunctional adenovirus DNA-binding protein (DBP). A cloned E2A gene was first mutagenized in vitro and then was introduced into the viral genome by in vivo recombination. The E2A mutants were propagated by growth in human cell lines which express an integrated copy of the DBP gene under the control of a dexamethasone-inducible promoter (D. F. Klessig, D. E. Brough, and V. Cleghon, Mol. Cell. Biol. 4:1354-1362, 1984). The protocol was used to construct five adenovirus mutants, Ad5d1801 through Ad5d1805, which contained deletions in E2A. One of the mutants, Ad5d1802, made no detectable DBP and thus represents the first DBP-negative adenovirus mutant, while the four other mutants made truncated DBP-related polypeptides. All five mutants were completely defective for growth and plaque formation on HeLa cell monolayers. Furthermore, the two mutants which were tested, Ad5d1801 and Ad5d1802, did not replicate their DNA in HeLa cells. The mutant Ad5d1804 encoded a truncated DBP-related protein which contained an entire amino-terminal domain derived from the host range mutant Ad5hr404, a variant of Ad5 which multiplies efficiently in monkey cells. While results of a previous study suggest that the amino-terminal domain of DBP could act independently of the carboxyl-terminal domain to enhance late gene expression in monkey cells, the Ad5d1804 polypeptide failed to relieve the block to late viral protein synthesis in monkey cells. The mutant Ad5d1802 was used to study the role of DBP in the regulation of early adenovirus gene expression in infected HeLa cells. These experiments show that E2A mRNA levels are consistently reduced approximately fivefold in Ad5d1802-infected cells, suggesting either a role for DBP in the expression of its own gene or a cis-acting defect caused by the E2A deletion. DBP does not appear to play a significant role in the regulation of adenovirus early regions 1A, 1B, 3, or 4 mRNA levels in infected HeLa cell monolayers since wild-type Ad5- and Ad5d1802-infected cells showed very little difference in the patterns of expression of these genes.

    Title Restricted Changes in the Adenovirus Dna-binding Protein That Lead to Extended Host Range or Temperature-sensitive Phenotypes.
    Date July 1985
    Journal Journal of Virology
    Excerpt

    Human adenovirus fails to multiply efficiently in monkey cells owing to a block to late viral gene expression. Ad2hr400 through Ad2hr403 are a set of host range (hr) mutants which were selected for their ability to readily grow in these cells at 37 degrees C. The mutations responsible for this extended host range have previously been mapped to the 5' portion of the gene encoding the 72-kilodalton DNA-binding protein (DBP). DNA sequence analyses indicate that all four hr mutants contain the same alteration at coding triplet 130, which changes a histidine codon to a tyrosine codon. These results extend those of Anderson et al. (J. Virol. 48:31-39, 1983), which suggested that only this change in the DBP amino acid sequence can expand adenovirus host range to monkey cells. The hr phenotype does not appear to require phosphorylation of this tyrosine residue, since no phosphotyrosine was detected in DBP isolated from Ad2hr400-infected monkey cells. The hr mutants Ad2hr400 through Ad2hr403, however, are cold sensitive for growth in monkey cells. The mutant Ad2ts400, which was derived from Ad2hr400, represents a second class of hr mutants which can grow efficiently in monkey cells at 32.5 degrees C. The cold-resistant hr mutation of Ad2ts400 has previously been mapped to the 5' region of the DBP gene (map units 63.6 through 66). DNA sequence analysis of this region shows that this mutant contains the original hr alteration at coding triplet 130 as well as a second alteration at coding triplet 148, which changes an alanine codon to a valine codon. We suspect that the alterations at amino acids 130 and 148 change the structure of the amino-terminal domain of the DBP, allowing it to better interact with monkey cell components required for late viral gene expression. Ad2ts400 also contains a temperature-sensitive mutation which has previously been mapped to the 3' portion of the DBP gene (map units 61.3 through 63.6). Sequence analysis of this region indicates that the DBP coding triplet 413 has been altered. This change from a serine codon to a proline codon is the same alteration reported in the previously sequenced DBP mutants Ad5ts125 (W. Kruijer et al., Nucleic Acids Res. 9:4439-4457, 1981) and Ad5ts107 (W. Kruijer et al., Virology 124:425-433, 1983). Thus it appears that only a very limited number of changes in either the 5' or the 3' portion of the DBP gene can give rise to the hr or temperature-sensitive phenotypes, respectively.

    Title Halothane, Isoflurane, and Enflurane Mac in Pregnant and Nonpregnant Female and Male Mice and Rats.
    Date April 1985
    Journal Anesthesiology
    Excerpt

    The MAC of halothane, isoflurane, and enflurane was determined using the tail-clamp technique in pregnant female, nonpregnant female, and male Swiss Webster mice (n = 216) and Sprague-Dawley rats (n = 112). Mean MAC values (+/-SD) for halothane, isoflurane, and enflurane in mice were 0.95 +/- 0.07%, 1.34 +/- 0.10%, and 1.95 +/- 0.16%, respectively; values in rats were 1.03 +/- 0.04%, 1.46 +/- 0.06%, and 2.21 +/- 0.08%, respectively, all significantly higher than in mice. Neither the sex of the animals nor whether female animals were pregnant influenced the results.

    Title Reproduction and Fetal Development in Rats Exposed to Nitrous Oxide.
    Date December 1984
    Journal Teratology
    Excerpt

    The effects of 24 hours of nitrous oxide exposure on reproductive indices and fetal development were examined in Sprague-Dawley rats. Four different experiments employing four concentrations of nitrous oxide--0.75%, 7.5%, 25% and 75%--established that the threshold of toxicity was greater than 25%. At 75% nitrous oxide there was a significant increase in early and late resorptions, and a consistent teratogenic effect (e.g., runts, ocular malformations, limb deformities). Neither the stress of shipping dams while pregnant nor the withholding of food during nitrous oxide exposure resulted in additional adverse effects. Exposure to 25% nitrous oxide was associated with increased deoxyuridine suppression values; however, adverse reproductive effects were not seen at this nitrous oxide concentration. The results of this and other studies which have examined the reproductive and teratogenic effects of nitrous oxide do not contraindicate its use in operating rooms nor, when necessary, as an anesthetic for pregnant surgical patients.

    Title Liver Function and Anesthetic Metabolism in Rats with Chronic Renal Impairment.
    Date May 1984
    Journal Anesthesiology
    Excerpt

    Patients and rats with chronic renal insufficiency (CRI) anesthetized with enflurane do not have significantly greater increases in postoperative serum inorganic fluoride levels when compared with subjects with normal renal function. The authors chose to investigate whether this observation is due to decreased anesthetic metabolism, secondary to the renal disease. Thus, male Fischer 344 rats with surgically induced CRI were studied to determine the effect of severe renal impairment: first, on in vivo hepatic function as measured by a serum liver enzyme profile, and second, on in vitro hepatic metabolism as indicated by microsomal anesthetic defluorination rates and cytochrome P-450 levels. Rats were operated on in two stages, 1 week apart, and assigned to one of three groups. Group 1 rats had a capsule stripping of each kidney. Group 2 rats had a capsule stripping of one kidney and then a nephrectomy of the other. Group 3 rats had the upper and lower poles of one kidney excised and then a nephrectomy of the other. There was no change in renal function in rats from Group 1 and 2. Chronic renal insufficiency in Group 3 rats was manifested by threefold elevations in serum creatinine and urea nitrogen levels and reciprocal decreases in clearances. After 89-98 days, blood was obtained for a serum liver enzyme profile and rats were killed for determination of in vitro hepatic metabolism. There were no changes suggestive of hepatic damage.(ABSTRACT TRUNCATED AT 250 WORDS)

    Title The Function(s) Provided by the Adenovirus-specified, Dna-binding Protein Required for Viral Late Gene Expression is Independent of the Role of the Protein in Viral Dna Replication.
    Date February 1984
    Journal Journal of Virology
    Excerpt

    The adenovirus type 2 (Ad2) host range mutant Ad2hr400 grows efficiently in cultured monkey cells at 37 degrees C, but is cold sensitive for plaque formation and late gene expression at 32.5 degrees C. After nitrous acid mutagenesis of an Ad2hr400 stock, cold-resistant variants were selected in CV1 monkey cells at 32.5 degrees C. One such variant, Ad2ts400, was also temperature sensitive (ts) for growth in both CV1 and HeLa cells. Marker rescue analysis has been used to show that the two phenotypes, cold resistant and temperature sensitive, are due to two independent mutations, each of which resides in a different segment of the gene encoding the 72-kilodalton DNA binding protein (DBP). The cold-resistant mutation (map coordinates 63.6 to 66) is a host range alteration that enhances the ability of the virus to express late genes and grow productively in monkey cells at 32.5 degrees C. The temperature-sensitive mutation is in the same complementation group and maps to the same segment of the DBP gene (map coordinates 61.3 to 63.6) as the well-characterized DBP mutant Ad5ts125. Like Ad5ts125, Ad2ts400 is unable to replicate viral DNA or to properly shut off early mRNA expression at the nonpermissive temperature. Two sets of experiments with Ad2ts400 suggest that DBP contains separate functional domains. First, when CV1 cells are coinfected at the nonpermissive temperature with Ad2 plus Ad2ts400 (Ad2 allows DNA replication and entry into, but not completion of, the late phase of infection), normal late gene expression and productive growth occur. Second, temperature shift experiments show that, although DNA replication is severely restricted at the nonpermissive temperature in ts400-infected monkey cells, late gene expression occurs normally. These results indicate that the DBP activity required for normal late gene expression in monkey cells is functional even when the DBP's DNA replication activity is disrupted.

    Title Halothane Inhibits Metabolism of Enflurane in Fischer 344 Rats.
    Date December 1983
    Journal Anesthesiology
    Excerpt

    The authors investigated the effect of prior administration of halothane upon the metabolism of enflurane. Twenty-four, one-year-old male, Fischer 344 rats were assigned randomly to four anesthetic exposure groups. Groups 1 and 2 were controls exposed only to halothane and enflurane, respectively. Group 3 was exposed for 1 h to 0.3% halothane, followed by 2 h of 1% enflurane. Group 4 was exposed for 1 h to 1% halothane and then to 2 h of 1% enflurane. Blood samples were taken prior to, immediately following, and 1, 24, and 48 h after anesthetic exposure. Serum was assayed for inorganic fluoride (F-), SGOT and SGPT. Twenty-four-hour urinary collections were assayed for F excretion. Group 1 rats exposed to halothane alone had the lowest peak mean serum F- (5.0 microM). Group 2 rats exposed to enflurane alone had the highest serum F concentration 4 h after anesthesia (18.7 microM). Peak serum F in Group 3 rats (9.5 microM) was significantly lower than in Group 2 rats (enflurane control). In Group 4 rats, serum F- was not significantly different from Group 1 rats (halothane control) at any time. In the first 24 h after anesthetic exposure, urinary F- excretion in Groups 2 and 3 was significantly higher than in Groups 1 and 4. This study demonstrated that prior exposure to halothane reduced the metabolism of enflurane; previous work suggested that this was due to an interaction of halothane with hepatic cytochrome P-450.(ABSTRACT TRUNCATED AT 250 WORDS)

    Title Thymidine and Methionine Syntheses in Pregnant Rats Exposed to Nitrous Oxide.
    Date August 1983
    Journal Anesthesia and Analgesia
    Excerpt

    The dose-dependent effects of nitrous oxide on thymidine and methionine syntheses were investigated in pregnant rats. Female Sprague-Dawley rats were exposed on day 9 of gestation to 0.75%, 7.5%, or 75% nitrous oxide for 24 h. Immediately and 72 h after exposure, a deoxyuridine-suppression test was performed on maternal bone marrow and a methionine synthetase assay was performed on maternal liver to assess thymidine and methionine syntheses, respectively. Inhibition of thymidine synthesis was seen after exposure to 7.5% and 75%, but not after 0.75%, nitrous oxide. Recovery was complete 72 h after exposure. Methionine synthetase activity was abolished at all concentrations of nitrous oxide tested and did not return to control values 72 h after exposure. Fetal weight and gross appearance were not affected by exposure to nitrous oxide; however, the observed decrease in thymidine and methionine syntheses after nitrous oxide exposure may account for its teratogenic effects.

    Title Germ Cell Studies in Mice After Prolonged Exposure to Nitrous Oxide.
    Date June 1983
    Journal Toxicology and Applied Pharmacology
    Excerpt

    Male and female Swiss Webster (SW) mice, age 13 to 14 weeks, were exposed by inhalation for 4 hr per day, 5 days per week, for 14 weeks, to either room air, 0.5% nitrous oxide, 5.0% nitrous oxide, or 50% nitrous oxide. Murine germ cells were examined for evidence of injury after this exposure. A group of male mice were treated with methyl methanesulfonate (MMS) as a positive control for sperm abnormalities while a group of female mice were treated with 3-methylcholanthrene (3-MC) as a positive control for oocyte destruction. There were no significant differences among the four inhalation exposure groups in testes weight, percentage of abnormally shaped sperm, sperm count, or histologic appearance of the testes; the mean percentage (+/- SE) of abnormal sperm ranged from 8.9 +/- 2.4 (5.0% nitrous oxide) to 13.5 +/- 0.5 (50% nitrous oxide) with a concurrent control value of 10.4 +/- 2.3%. In the positive control experiment, 25.2 +/- 4.1% of sperm from mice treated with MMS were abnormal compared with 2.5 +/- 0.3% of sperm from mice treated with saline (p less than 0.001), indicating that sperm of SW mice are sensitive to chemical damage. There was no significant difference between the mean number of oocytes in mice treated with 50% nitrous oxide (33.3 +/- 14.4) and in control mice (29.8 +/- 8.0). In the positive control experiment, mice treated with 3-MC had significantly fewer (p less than 0.001) primordial oocytes, 67.2 +/- 19.5 compared with control mice, 222.4 +/- 21.9, indicating that this strain is sensitive to chemical damage of the ovary. Thus, murine germ cells showed no evidence of toxic effects due to prolonged exposure to nitrous oxide.

    Title Metabolism by Rat Hepatic Microsomes of Fluorinated Ether Anesthetics Following Ethanol Consumption.
    Date April 1983
    Journal Anesthesiology
    Excerpt

    The possibility that the metabolism of volatile inhalational anesthetics is altered following chronic ethanol consumption was investigated in male Fischer 344 rats. The hepatic microsomal defluorination rates of methoxyflurane, enflurane, and sevoflurane were determined for pair-fed rats receiving ethanol with normal caloric or with 50% of normal caloric intake. For comparison, the effects of phenobarbital treatment on anesthetic defluorination rates also were examined. Fourteen days of ad libitum consumption of 16% ethanol resulted in maximal defluorination rates of the above anesthetics. No overt signs of ethanol toxicity were observed. Ethanol-treated rats with a normal caloric intake had significantly increased microsomal defluorination rates per mg protein compared with pair-fed control rats as follows: methoxyflurane, 190% of control; enflurane, 298% of control; and sevoflurane, 301% of control. Ethanol-treated animals with 50% of normal caloric intake showed similar elevations in microsomal defluorination rates when compared with pair-fed controls. Phenobarbital treatment significantly increased the rate of methoxyflurane defluorination (673% of control), whereas the rates of sevoflurane defluorination (127% of control) and enflurane defluorination (86% of control) were not altered significantly. Phenobarbital treatment increased the microsomal content of cytochrome P-450, while ethanol treatment did not. This study demonstrated that regardless of total caloric intake, chronic ethanol consumption increases defluorination of inhalation anesthetics in Fischer 344 rats. It also illustrated that the two enzyme-inducing agents are unique with respect to the degree to which they enhance anesthetic defluorination.

    Title Reproduction and Fetal Development in Mice Chronically Exposed to Nitrous Oxide.
    Date December 1982
    Journal Teratology
    Excerpt

    The effects of exposure to nitrous oxide on reproductive indices, fetal development, and male fertility were examined in Swiss/ICR mice. In experiment I, female mice were exposed for 4 hours per day on days 6-15 of pregnancy, to 0.5% (5,000 ppm), 5.0% (50,000 ppm), or 50% (500,000 ppm) nitrous oxide. Control mice were untreated, exposed to compressed air, or treated with retinoic acid on day 8 of gestation. In experiment II, male mice were treated, as above, for 9 weeks and then mated nightly for 7 nights to untreated, virgin females. In experiment I, 1,761 fetuses from 154 dams were examined and found to be without evidence of adverse nitrous oxide treatment effects. In experiment II there were no differences among the groups in the ability of males to impregnate females or in litter size, fetal wastage, or fetal size. When we compare nitrous oxide with other inhalation anesthetics we have studied employing a similar protocol, we find the order of reproductive toxicity to be: halothane greater than enflurane greater than methoxyflurane greater than nitrous oxide. None of the agents were toxic, however, at the trace concentrations usually found in operating rooms.

    Title Transient Effects on the Initial Rate of Oxygenation of Red Blood Cells.
    Date May 1982
    Journal Bulletin of Mathematical Biology
    Title Factors Defining the Rate of Oxygen Uptake by the Red Blood Cell.
    Date May 1982
    Journal Bulletin of Mathematical Biology
    Title Deuterated Methoxyflurane Anesthesia and Renal Function in Fischer 344 Rats.
    Date April 1982
    Journal Anesthesiology
    Excerpt

    Inorganic fluoride (F-) production and renal function were assessed in six groups of Fischer 344 rats administered either methoxyflurane (MOF) or deuterated methoxyflurane (d4-MOF). One untreated and one phenobarbital (PB)-treated group were exposed for two hours to either air, 0.5 per cent (V/v) MOF, or 0.5 per cent (v/v) d4-MOF. Serum and urinary F- and serum urea nitrogen and creatinine were measured. Urine volume and urinary F- excretion were only slightly greater among MOF than among d4-MOF exposed animals. Pretreatment with PB, however, greatly enhanced F- production in MOF-exposed animals leading to marked renal impairment but only slightly enhanced F- production in d4-MOF animals leading to mild renal impairment. Thus, only in PB-pretreated animals could a biologically significant difference in nephrotoxicity be demonstrated for MOF and d4-MOF.

    Title Hydrodynamic and Diffusion Considerations of Rapid-mix Experiments with Red Blood Cells.
    Date October 1981
    Journal Biophysical Journal
    Excerpt

    From studies of the oxygenation rate of red blood cells (RBC) using rapid-mix techniques, it has been suggested that RBC are surrounded by a stagnant layer of water that does not (or cannot) mix with the rest of the water. A consideration of the appropriate hydrodynamics and convective diffusion rates shows that a mixer can reduce the resolution time to approximately 1 ms (or possibly less) and give a diffusion layer around the TBC that is approximately 1 micron thick. In stopped flow equipment it expands to approximately 4 micron over approximately 10 ms, whereas in continuous flow work the diffusion layers expands slightly less rapidly and less far. Thus the rate of oxygenation of TBC should be slower when measured by stopped flow techniques than by continuous flow apparatus for which the rate will depend weakly on the Reynolds number of the flow in the interrogation tube.

    Title Hepatitis B Virus, Hepatitis A Virus and Persistently Elevated Aminotransferases in Hemophiliacs.
    Date August 1981
    Journal Journal of Medical Virology
    Excerpt

    To determine the exposure to hepatitis A and hepatitis B viruses (HAV, HBV) following intravenous replacement therapy in patients with classic hemophilia and to assess the role of these viruses in persistently elevated aminotransferases, sera were studied from 136 patients from 9 months to 67 years of age were transfused with either single-donor cryoprecipitate (CRYO) or Antihemophilic Factor Concentrate (AHF) for periods ranging from a few months to 15 years. Serologic evidence of past or present infection with HBV was detected in 90% of all 136 patients and in 85% of those 34 patients 10 years of age or younger. Sixty-four percent of those with serologic markers of hepatitis B had high titers of antibody to the hepatitis B surface antigen and low titers of antibody to the hepatitis B core antigen. These findings are consistent with the known high frequency of early exposure to HBV in hemophiliacs receiving replacement therapy and with recovery from these hepatitis B infections. Sixteen percent of these patients had persistently elevated aminotransferase levels; HBV could not be implicated as the cause of the enzyme elevations in most of these cases.

    Title Renal Function in Fischer 344 Rats with Chronic Renal Impairment After Administration of Enflurane and Gentamicin.
    Date March 1981
    Journal Anesthesiology
    Excerpt

    To assess the potential for producing nephrotoxicity in rats with abnormal renal function, the renal effects of enflurane or halothane anesthesia, 1 MAC for two hours, were examined in six groups of six Fischer 344 rats each with surgically induced chronic renal impairment. As an additional predisposing factor, gentamicin, 5 mg/kg/day, was administered for one week before and for one week after anesthesia to three of the groups, one anesthetized with enflurane, one anesthetized with halothane, and one unanesthetized. No significant change in renal function could be attributed to either anesthetic agent. Serum inorganic fluoride levels four hours and 24 hours after enflurane anesthesia were similar in the gentamicin-treated and the non-gentamicin-treated groups. Clinically small but statistically significant increases in serum creatinine concentration and urinary flow occurred in all three gentamicin-treated groups during the period of treatment. Anesthesia with either enflurane or halothane in rats with chronic renal impairment treated with gentamicin did not result in additional renal damage.

    Title Metabolism by Rat Hepatic Microsomes of Fluorinated Ether Anesthetics Following Isoniazid Administration.
    Date March 1981
    Journal Anesthesiology
    Excerpt

    The possibility that enflurane defluorination is increased following treatment with isoniazid was investigated in male Fischer 344 rats. The effects of various isoniazid dosage regimens on the hepatic microsomal defluorination rates of enflurane were compared with those of several other ether anesthetics, and the conditions for production of maximal enflurane defluorination rates were determined. Seven to ten days of treatment with 50 mg/kg/day isoniazid (Nydrazid) resulted in maximal rates of defluorination of methoxyflurane, enflurane, isoflurane, and sevoflurane with no overt sign of toxicity. Compared with saline treatment of control rats, isoniazid increased defluorination of enflurane 370 per cent, methoxyflurane 259 per cent, sevoflurane 283 per cent, and isoflurane 168 per cent. Previous studies have shown that while the enzyme inducer phenobarbital increased in vitro rates of methoxyflurane defluorination approximately 1000 per cent, the rate of enflurane defluorination remained unchanged or increased by 100 per cent at most. In this study, enhanced hepatic microsomal defluorination was not associated with an increase in cytochrome P-450 per mg protein. Anesthetic defluorination rates were not altered by treatment with chlorobutanol, the preservative contained in Nydrazid.

    Title Metabolic and Toxicologic Studies with Enflurane in Swiss/icr Mice.
    Date February 1981
    Journal Journal of Environmental Pathology and Toxicology
    Excerpt

    Swiss/ICR mice were tested to determine whether the volatile ether anesthetic, enflurane, causes induction of anesthetic defluorination and organ toxicity. Mice were exposed in utero and postnatally to 0.01, 0.1 and 1.0 volumes percent enflurane vapor. Body weight was measured at frequent intervals throughout the experiment. Animals were sacrificed at 73 days of age and liver microsomal cytochrome P-450 content and the rate of defluorination of enflurane, isoflurane, methoxyflurane ans sevoflurane were determined. In addition, the liver, kidney and testis were weighed and examined histologically for drug induced damage. The maximum tolerated dose of enflurane delivered over a twelve week period was determined to be 0.5 volumes percent for four hours a day, five days a week. Even at this high dose there was no evidence in either sex of liver, kidney or testicular damage. Following enflurane exposure, neither the liver microsomal cytochrome P-450 content nor the rate of anesthetic defluorination was increased. The rate of in vitro inorganic fluoride production per unit time was greatest for methoxyflurane, and approximately equal for enflurane, isoflurane and sevoflurane. Since there was no evidence of enzyme induction or specific organ toxicity, it was concluded that enflurane is a comparatively nontoxic volatile anesthetic under conditions of this study.

    Title Liver Dysfunction in Pennsylvania's Multitransfused Hemophiliacs.
    Date January 1981
    Journal Digestive Diseases and Sciences
    Excerpt

    Transaminase values [alanine amino transferase (ALT) and aspartate amino transferase (AST)] and markers for hepatitis B were serially determined in 558 hemophiliacs exposed to blood products. Hepatitis B surface antigen (HBsAg) persistent for over 12 months was present in 6% of the patients. Antibody to hepatitis B surface antigen (anti-HBs) was noted in 90% of the 259 patients treated with factor VIII or IX concentrates but in only 49% of the 43 patients treated with fresh frozen plasma (FFP) or cryoprecipitate. Persistently abnormal transaminase values were noted in 31% of the patients treated with commercial concentrates but in only one (2%) of the patients exposed to cryoprecipitate or FFP. This difference continued even when the two groups of patients were matched for the amount of blood products, up to 50,000 units, which they had received in the study period. In the concentrate-treated patients, no correlation could be found between transaminase values and the number of units of factor VIII or IX they had received during the six years of the study (1973-1978).

    Title Enflurane Has No Effect on Haemopoiesis in Mice.
    Date September 1980
    Journal British Journal of Anaesthesia
    Excerpt

    Male and female Swiss/ICR mice were exposed to 0.3% enflurane in air, 4 h per day, 5 days per week for 52 weeks. A control group was exposed to air alone. After 52 weeks, all animals were sacrificed and peripheral blood and bone marrow samples were examined for alterations in haemopoiesis. In general, there was no difference between treated and control groups.

    Title Fetal Morphology in Mice Exposed to Halothane.
    Date February 1980
    Journal Anesthesiology
    Excerpt

    The teratogenic potential of subanesthetic and anesthetic exposure to halothane was studied in Swiss/ICR mice. Two treatment regimens were employed: daily exposure of males and females for nine weeks prior to conception and on days 1 through 17 of pregnancy; and exposure of females only on days 6 through 15 of pregnancy. Mice were exposed to subanesthetic concentrations of halothane for 0.025, 0.1, 0.4, and 1.2 MAC hours/day; anesthetic exposure was 4.0 MAC hours/day. Fetal morphologic development was normal at the two lowest exposures. Exposures of 0.4 MAC hours/day and more were associated with decreased fetal ossification. At the 1.2 MAC hour/day exposure, renal pelvic masturation was retarded and the incidence of skeletal variants was increased. The incidences of major malformations and minor anomalies were not increased following exposure to subanesthetic concentrations of halothane. Anesthetic exposure to 4.0 MAC hours/day was lethal to both dams and embryos, and resulted in major developmental malformations in surviving fetuses. These effects were probably due to altered maternal physiologic status. It is concluded that exposure of mice to subanesthetic concentrations of halothane does not result in important morphologic abnormalities in their offspring.

    Title Renal Effects of Enflurane Anesthesia in Fischer 344 Rats with Pre-existing Renal Insufficiency.
    Date December 1979
    Journal The Journal of Pharmacology and Experimental Therapeutics
    Excerpt

    Chronic renal insufficiency was produced surgically in Fischer 344 rats in order to evaluate the effects of enflurane anesthesia in animals with impaired renal function. Three groups of rats were anesthetized with enflurane: a control group without impairment of renal function (n = 7); a group with minimal impairment of renal function (n = 6); and a group with moderately severe renal impairment (n = 9). Another group of rats with moderately severe renal impairment (n = 8) was anesthetized with halothane. Two hours of anesthesia resulted only in mild transient depression of urea clearance in all groups. Six hours of anesthesia resulted in a 5 to 10 ml/day increase of urinary output in all groups and small increases in urea nitrogen levels in both groups with moderately severe renal impairment. Deterioration of the model was noted late in the experiment; at sacrifice, animals that had been anesthetized with enflurance and four with halothane had terminal renal failure. The morphological lesion in both groups was similar, resembling glomerulonephritis. Thus, there was no difference in the renal response to enflurane or halothane anesthesia among rats with chronic renal insufficiency.

    Title Effect of Phenytoin (dph) Treatment on Methoxyflurane Metabolism in Rats.
    Date September 1979
    Journal The Journal of Pharmacology and Experimental Therapeutics
    Excerpt

    The toxicity and metabolism of the fluorinated anesthetic methoxyflurane were compared in Fischer 344 rats pretreated with phenytoin or phenobarbital. Treatment with either drug potentiated the polyuric effects of methoxyflurane by more than 100%. Also, serum inorganic fluoride (F-) levels and urinary F- excretions after methoxyflurane exposure were comparable in phenytoin- and phenobarbital-treated rats, a 26 to 49% increase as compared to rats treated with methoxyflurane alone. In vitro, 10-fold increases in the rate of hepatic microsomal methoxyflurane defluorination were observed after treatment of rats with either phenytoin or phenobarbital. Kinetic studies with microsomes demonstrated inhibition of methoxyflurane defluorination in the presence of phenytoin. Defluorination of three additional fluorinated ether anesthetics, enflurane, isoflurane and sevoflurane, also was examined in vitro. Phenytoin and phenobarbital treatment resulted in similar enhancement of defluorination of the latter two anesthetics, but not enflurane. Phenytoin and phenobarbital treatment increase defluorination of fluorinated ether anesthetics to approximately the same extent in vitro and in vivo in Fischer 344 rats.

    Title Carcinogenicity of Halothane in Swiss/icr Mice.
    Date August 1979
    Journal Anesthesiology
    Excerpt

    A simplified in-vivo bioassay system was used to test the carcinogenic potential of halothane in Swiss/ICR mice. Halothane was tested only at its maximum tolerated dose, and histologic examination was performed only on tumor masses and other grossly abnormal tissues found at necropsy. Two groups, each of 15 timed pregnant mice, were exposed to either halothane, 500 ppm (0.05 per cent), or compressed air for two hours on days 10--19 of pregnancy. Five days after birth the offspring were similarly exposed, three times weekly, for 78 weeks. After a ten-week, no-treatment, observation period, all remaining mice were examined by necropsy. Mice dying or killed in extremis before final sacrifice at 88 weeks of age also underwent complete gross necropsy unless extensive cannibalism or autolysis precluded examination. The incidences of malignant tumors, hepatomas or modular hyperplasias, and benign tumors in halothane-treated mice were 7, 6, and 20 per cent, respectively; there were similar incidences of these lesions in control animals. It is concluded that under the conditions of this experiment, lifetime administration of halothane at its maximum tolerated dose is not associated with an increased incidence of neoplasia in Swiss/ICR mice.

    Title Is Enflurane Defluorination Inducible in Man?
    Date June 1979
    Journal Anesthesiology
    Title Fluroxene Mutagenicity.
    Date May 1979
    Journal Mutation Research
    Excerpt

    The commercially available volatile anesthetic fluroxene (2,2,2-trifluoroethyl vinyl ether) which contains the stabilizer N-phenyl-1-napthylamine, was tested for mutagenicity using four strains of S. typhimurium, TA1535, TA1537, TA98 and TA100, and one strain of E. coli, WP2. In addition, purified fluroxene; N-phenyl-1-napthylamine; trifluoroethanol, a major metabolite of fluoroxene; and urine from rats anesthetized with fluroxene were tested. Several procedures were utilized including exposure of bacteria to vapor in desiccators and in liquid suspension. Results indicate that fluroxene, but not its stabilizer, was mutagenic to strains TA1535, TA100 and WP2 only in liquid suspension and only in the presence of a rat-liver enzyme system. Trifluoroethanol and urine from fluroxene-treated rat were not mutagenic to any strain of bacteria. These findings indicate that fluroxene is a promutagen which requires preincubation before it is recognized. Further experiments were performed with enzymes prepared from mouse, hamster and human liver. Fluroxene was mutagenic only in the presence of enzymes prepared from Aroclor 1254 pretreated rodents. Since fluroxene was not mutagenic in the presence of enzymes prepared from three human livers, the significance of these findings to man are unclear.

    Title Parametric Motion of Energy Levels: Curvature Distribution.
    Date
    Journal Physical Review. A
    Title Field-theoretical Model Inspired by Adiabatic-ansatz Eigenvalue Problems.
    Date
    Journal Physical Review. A
    Title Hydrogen Negative Ion: Semiclassical Quantization and Weak-magnetic-field Effect.
    Date
    Journal Physical Review. A
    Title Nonadiabatic Transitions and Gauge Structure.
    Date
    Journal Physical Review. A
    Title Experimental Evidence for the Divergence of a Transport Coefficient in a Quasi-two-dimensional Fluid.
    Date
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Title Self-diffusion in Dilute Quasi-two-dimensional Hard Sphere Suspensions: Evanescent Wave Light Scattering and Video Microscopy Studies.
    Date
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Title Solitonlike Structure in the Parametric Distortions of Bounded-system Energy Spectra.
    Date
    Journal Physical Review Letters
    Title Observations of First-order Liquid-to-hexatic and Hexatic-to-solid Phase Transitions in a Confined Colloid Suspension.
    Date
    Journal Physical Review Letters
    Title Optical Control of Reactions
    Date
    Journal Nature
    Title Nature of the Transition from Two- to Three-dimensional Ordering in a Confined Colloidal Suspension
    Date
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Excerpt

    We report the results of extensive molecular dynamics simulations of solid-to-solid transitions in two- to six-layer colloidal suspensions confined between two smooth parallel walls. The studies are designed to elucidate the ordered particle packings that interpolate between the structures of two- and three-dimensional crystals in a confined space. At a fixed density per layer, as the wall separation increases we find a sequence of stable phases, each characterized by uniform amplitude buckling along the normal to the layer planes. The buckling is coupled to an in-plane ordering transition. The buckled phases alternate with phases whose structures contain only parallel planes of particles. The relative densities of the positively and negatively displaced particles in a buckled layer, the in-plane structures, and the behavior with respect to increasing wall separation of the split density distribution that characterizes a buckled layer, clearly identify these layers as intermediates in the reconstructive transformations ntriangle up-->(n+1) square that occur when the character of the constrained space evolves from being two dimensional to being three dimensional (triangle up denotes layers with hexagonal packing symmetry, while square denotes layers with square packing symmetry). The two transitions, ntriangle up-->n-buckled-->(n+1) square, are found to be first order.

    Title Hexagonal to Square Lattice Conversion in Bilayer Systems
    Date
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Excerpt

    We report the results of extensive molecular dynamics simulations of the reconstructive hexagonal to square lattice conversion in bilayer colloid systems. Two types of interparticle potential were used to represent the colloid-colloid interactions in the suspension. One potential, due to Marcus and Rice, is designed to describe the interaction of sterically stabilized colloid particles. This potential has a term that represents the attraction between colloid particles when there is incipient overlap between the stabilizing brushes on their surfaces, a (soft repulsion) term that represents the entropy cost associated with interpenetration of the stabilizing brushes, and a term that represents core-core repulsion. The other potential we used is an almost hard core repulsion with continuous derivatives. Our results clearly show that the character of the reconstructive hexagonal to square lattice conversion in bilayer colloid systems is potential dependent. For a system with colloid-colloid interactions of the Marcus-Rice type, the packing of particles in the square array exhibits a large interlayer lattice spacing, with the particles located at the minima of the attractive well. In this case the hexagonal to square lattice transition is first order. For a system with hard core colloid-colloid interactions there are two degenerate stable intermediate phases, linear and zigzag rhombic, that are separated from the square lattice by strong first order transitions, and from the hexagonal lattice by either weak first or second order transitions.

    Title Melting Transition in a Quasi-two-dimensional Colloid Suspension: Influence of the Colloid-colloid Interaction
    Date
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Excerpt

    We report the results of a study, using digital video microscopy, of the melting transition in a quasi-two-dimensional suspension of uncharged silica spheres. This system was chosen to further test the dependence of the two-dimensional melting transition on the functional form of the colloid-colloid interaction. Our experimental data show that the solid phase undergoes a first order transition directly to the liquid phase. The system studied yields no evidence of the existence of a hexatic phase interpolating between the solid and liquid phases in the melting process.

    Title Direct Measurements of Constrained Brownian Motion of an Isolated Sphere Between Two Walls
    Date
    Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
    Excerpt

    We report the results of direct measurements, using video microscopy in combination with optical tweezers, of constrained diffusion of an isolated uncharged PMMA sphere in a density-matched fluid confined between two parallel flat walls. Our experimental methodology allows us to study the hindered diffusion of the sphere as an explicit function of its distance from the walls, without interference from sedimentation or from electrostatic interaction between the particle and the walls. The measured diffusion coefficients are used to test the predictions of the wall drag effect predicted by several approximate theoretical analyses. We find a quantitative agreement with the behavior predicted using a hydrodynamic analysis that independently superimposes the wall drag effects arising from each wall. Our results imply, indirectly, that neglect of multiple interactions with the colloid sphere of the perturbations of the pressure and velocity fields induced by each wall leads to an underestimate of the influence of the wall on the drag force experienced by the particle.

    Title A Conjecture Concerning the Symmetries of Planar Nets and the Hard Disk Freezing Transition.
    Date
    Journal The Journal of Physical Chemistry. B
    Excerpt

    We examine the conjecture that in a 2D system of hard disks the packing fraction at which the continuous transition from the ordered 2D solid to the hexatic phase occurs, and that at which the very weak first-order or continuous transition from the hexatic to the fluid phase occurs, can be correlated with the packing fractions of patterned networks (tessellations) of disk positions that span the 2D space. We identify three tessellations that have less than close packed density, span 2D space, and have percolated continuity of disk-disk contact. One has a packing fraction of eta = 0.729, very slightly larger than the estimated packing fraction at the ordered solid-to-hexatic transition, eta = 0.723, and the other two have packing fractions of approximately 0.680, slightly smaller than that identified as the upper end of the stability range of the liquid phase, eta = 0.699. The region 0.680 < eta < 0.729 is identified with the hexatic domain. The end points of this region can be placed in correspondence with nets for which the defining unit structures are regular polygons, but not the hexatic domain, in which there are randomly dispersed clusters that need not be regular polygons. The densities at which the percolated tessellations span the 2D space are regarded as special points along the density axis. We suggest that the possibility of forming different symmetry nets with sensibly the same packing fraction is a geometric analogue of a bifurcation condition that divides the configuration space into qualitatively different domains, and that the onset and end of the hexatic region are correlated with such divisions of the configuration space.

    Title Density Distribution in the Liquid Hg-sapphire Interface.
    Date
    Journal The Journal of Physical Chemistry. A
    Excerpt

    We present the results of a computer simulation study of the liquid density distribution normal to the interface between liquid Hg and the reconstructed (0001) face of sapphire. The simulations are based on an extension of the self-consistent quantum Monte Carlo scheme previously used to study the structure of the liquid metal-vapor interface. The calculated density distribution is in very good agreement with that inferred from the recent experimental data of Tamam et al. ( J. Phys. Chem. Lett. 2010 , 1 , 1041 - 1045 ). We conclude that, to account for the difference in structure between the liquid Hg-vapor and liquid-Hg-reconstructed (0001) Al(2)O(3) interfaces, it is not necessary to assume there is charge transfer from the Hg to the Al(2)O(3). Rather, the available experimental data are adequately reproduced when the van der Waals interactions of the Al and O atoms with Hg atoms and the exclusion of electron density from Al(2)O(3) via repulsion of the electrons from the closed shells of the ions in the solid are accounted for.

    Title Nitric Oxide-mediated Dispersal in Single- and Multi-species Biofilms of Clinically and Industrially Relevant Microorganisms.
    Date
    Journal Microbial Biotechnology
    Excerpt

    Strategies to induce biofilm dispersal are of interest due to their potential to prevent biofilm formation and biofilm-related infections. Nitric oxide (NO), an important messenger molecule in biological systems, was previously identified as a signal for dispersal in biofilms of the model organism Pseudomonas aeruginosa. In the present study, the use of NO as an anti-biofilm agent more broadly was assessed. Various NO donors, at concentrations estimated to generate NO levels in the picomolar and low nanomolar range, were tested on single-species biofilms of relevant microorganisms and on multi-species biofilms from water distribution and treatment systems. Nitric oxide-induced dispersal was observed in all biofilms assessed, and the average reduction of total biofilm surface was 63%. Moreover, biofilms exposed to low doses of NO were more susceptible to antimicrobial treatments than untreated biofilms. For example, the efficacy of conventional chlorine treatments at removing multi-species biofilms from water systems was increased by 20-fold in biofilms treated with NO compared with untreated biofilms. These data suggest that combined treatments with NO may allow for novel and improved strategies to control biofilms and have widespread applications in many environmental, industrial and clinical settings.

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