Browse Health
Pediatrician
37 years of experience
Video profile

Education ?

Medical School Score Rankings
Indiana University (1973)
  • Currently 3 of 4 apples
Top 50%

Awards & Distinctions ?

Associations
American Board of Pediatrics

Affiliations ?

Dr. Lyon is affiliated with 4 hospitals.

Hospital Affilations

Score

Rankings

  • Providence Alaska Medical Center
    PO Box 196604, Anchorage, AK 99519
    • Currently 1 of 4 crosses
  • Alaska Regional Hospital
    2801 Debarr Rd, Anchorage, AK 99508
    • Currently 1 of 4 crosses
  • Providence Extended Care Center
    4900 Eagle St, Anchorage, AK 99503
  • LaTouche Pediatrics, LLC
  • Publications & Research

    Dr. Lyon has contributed to 11 publications.
    Title Partial Purification and Characterization of a Bacteriocin Produced by Propionibacterium Thoenii.
    Date June 2010
    Journal Applied and Environmental Microbiology
    Excerpt

    A partially purified bacteriocin produced by Propionibacterium thoenii designated propionicin PLG-1 was found to be active against closely related species and exhibited a broad spectrum of activity against other microorganisms. Propionicin PLG-1 was found to be heat labile, sensitive to several proteolytic enzymes, and stable at pH 3 to 9. Propionicin PLG-1 was isolated from solid medium, partially purified by ammonium sulfate precipitation, and purified further by gel filtration. Gel filtration experiments revealed that bacteriocin PLG-1 was present as two different protein aggregates with apparent molecular weights of more than 150,000 and approximately 10,000. Resolution of these protein aggregates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a protein common to both with an apparent molecular weight of 10,000.

    Title Identification of Upper Respiratory Tract Pathogens Using Electrochemical Detection on an Oligonucleotide Microarray.
    Date September 2008
    Journal Plos One
    Excerpt

    Bacterial and viral upper respiratory infections (URI) produce highly variable clinical symptoms that cannot be used to identify the etiologic agent. Proper treatment, however, depends on correct identification of the pathogen involved as antibiotics provide little or no benefit with viral infections. Here we describe a rapid and sensitive genotyping assay and microarray for URI identification using standard amplification and hybridization techniques, with electrochemical detection (ECD) on a semiconductor-based oligonucleotide microarray. The assay was developed to detect four bacterial pathogens (Bordetella pertussis, Streptococcus pyogenes, Chlamydia pneumoniae and Mycoplasma pneumoniae) and 9 viral pathogens (adenovirus 4, coronavirus OC43, 229E and HK, influenza A and B, parainfluenza types 1, 2, and 3 and respiratory syncytial virus. This new platform forms the basis for a fully automated diagnostics system that is very flexible and can be customized to suit different or additional pathogens. Multiple probes on a flexible platform allow one to test probes empirically and then select highly reactive probes for further iterative evaluation. Because ECD uses an enzymatic reaction to create electrical signals that can be read directly from the array, there is no need for image analysis or for expensive and delicate optical scanning equipment. We show assay sensitivity and specificity that are excellent for a multiplexed format.

    Title Levosimendan for Patients with Impaired Left Ventricular Function Undergoing Cardiac Surgery.
    Date August 2007
    Journal Interactive Cardiovascular and Thoracic Surgery
    Excerpt

    The efficacy of levosimendan treatment for a low cardiac output status following cardiac surgery has not been established. Here, we review our initial experiences of the perioperative use of levosimendan. This study is a retrospective uncontrolled trial. Nine patients who underwent cardiac surgery, and developed a low cardiac output status resistant to conventional inotropic support, were given levosimendan. The mean preoperative ejection fraction was 35.2+/-3.4%. All patients were on concomitant inotropic agents and had previously undergone intra-aortic balloon pumping. Cardiac index increased immediately from 2.14+/-0.33 l/min/m(2) at baseline to 2.41+/-0.31 (P=0.02) at 1 h, rising to 2.67+/-0.43 (P<0.001) at 4 h after the loading dose was started. Similarly, the systemic vascular resistance index decreased from 2350+/-525 dynes/s/cm(-5)/m(2) at baseline to 1774+/-360 (P=0.002) at 4 h. In the case of all but one of the patients, either the dose of the concomitant inotropic support or the balloon pumping could be weaned down within 24 h after completion of the levosimendan infusion. No withdrawal of levosimendan was required. Levosimendan could constitute a new therapeutic option for postoperative low cardiac output.

    Title Use of Semiconductor-based Oligonucleotide Microarrays for Influenza a Virus Subtype Identification and Sequencing.
    Date November 2006
    Journal Journal of Clinical Microbiology
    Excerpt

    In the face of concerns over an influenza pandemic, identification of virulent influenza A virus isolates must be obtained quickly for effective responses. Rapid subtype identification, however, is difficult even in well-equipped virology laboratories or is unobtainable in the field under more austere conditions. Here we describe a genome assay and microarray design that can be used to rapidly identify influenza A virus hemagglutinin subtypes 1 through 15 and neuraminidase subtypes 1 through 9. Also described is an array-based enzymatic assay that can be used to sequence portions of both genes or any other sequence of interest.

    Title Relationship Between Elevated Preoperative Troponin T and Adverse Outcomes Following Cardiac Surgery.
    Date September 2003
    Journal Anz Journal of Surgery
    Excerpt

    BACKGROUND: The prognostic value of troponin T (TnT) has been demonstrated in patients following a myocardial infarction. There are limited data regarding the prognostic utility of preoperative TnT in patients undergoing cardiac surgery. The aim of the present study was to determine if elevated preoperative TnT is a predictor of more complex recovery outcomes in the cardiac surgical setting. METHODS: A single preoperative TnT measurement was assessed in 696 patients undergoing isolated coronary artery bypass graft surgery. Elevated preoperative TnT levels were classified as > or =0.2 ng/mL. Preoperative, intraoperative, intensive care and postoperative events were prospectively recorded for all patients, and retrospectively reviewed for the present study. RESULTS: Elevated preoperative TnT levels were detected in 10% (71/696) of patients. Compared to patients with normal TnT levels, elevated preoperative TnT increased the risk of mortality at 30 days (7% vs 1%, P = 0.004, odds ratio (OR) = 6.7) and 2 years (14% vs 3%, P < 0.001, OR = 5.0), and resulted in prolonged intensive care unit (ICU) stays (P < 0.001) and longer postoperative hospitalization (P < 0.001). Elevated preoperative TnT was also associated with an increased need for perioperative and postoperative cardiovascular support, early ischaemic change and postoperative congestive cardiac failure. In multivariate analyses preoperative TnT was a significant independent predictor of 30-day and 2-year mortality, and duration of ICU stay. CONCLUSIONS: Elevated preoperative TnT highlights a subgroup of cardiac surgical patients who are more likely to have a post-operative course with increased morbidity and mortality.

    Title Taqman Pcr for Detection of Vibrio Cholerae O1, O139, Non-o1, and Non-o139 in Pure Cultures, Raw Oysters, and Synthetic Seawater.
    Date December 2001
    Journal Applied and Environmental Microbiology
    Excerpt

    Vibrio cholerae is recognized as a leading human waterborne pathogen. Traditional diagnostic testing for Vibrio is not always reliable, because this bacterium can enter a viable but nonculturable state. Therefore, nucleic acid-based tests have emerged as a useful alternative to traditional enrichment testing. In this article, a TaqMan PCR assay is presented for quantitative detection of V. cholerae in pure cultures, oysters, and synthetic seawater. Primers and probe were designed from the nonclassical hemolysin (hlyA) sequence of V. cholerae strains. This probe was applied to DNA from 60 bacterial strains comprising 21 genera. The TaqMan PCR assay was positive for all of the strains of V. cholerae tested and negative for all other species of Vibrio tested. In addition, none of the other genera tested was amplified with the TaqMan primers and probe used in this study. The results of the TaqMan PCR with raw oysters and spiked with V. cholerae serotypes O1 and O139 were comparable to those of pure cultures. The sensitivity of the assay was in the range of 6 to 8 CFU g(-1) and 10 CFU ml(-1) in spiked raw oyster and synthetic seawater samples, respectively. The total assay could be completed in 3 h. Quantification of the Vibrio cells was linear over at least 6 log units. The TaqMan probe and primer set developed in this study can be used as a rapid screening tool for the presence of V. cholerae in oysters and seawater without prior isolation and characterization of the bacteria by traditional microbiological methods.

    Title Bacteria Associated with Processed Crawfish and Potential Toxin Production by Clostridium Botulinum Type E in Vacuum-packaged and Aerobically Packaged Crawfish Tails.
    Date October 2001
    Journal Journal of Food Protection
    Excerpt

    Refrigerated vacuum-packaged storage has been shown to increase significantly the shelf life of fresh fish and seafood products, but the effect, if any, on the outgrowth and toxin production of Clostridium botulinum type E on cooked crawfish is unknown. Microflora associated with live crawfish reflect the microbial populations of the harvest water and sediments in which they are living. The presence or absence of specific pathogens in either vacuum-packaged or air-permeable bags of cooked crawfish have not been thoroughly evaluated. This study evaluates the potential survival and outgrowth of biological hazards in both vacuum-packaged and air-permeable-packaged cooked crawfish held at 4 and 10 degrees C for 30 days. During shelf-life studies of vacuum-packaged and air-permeable-bagged cooked crawfish, a total of 31 bacterial species were isolated and identified from crawfish samples using both selective and nonselective media. The only pathogens isolated from both vacuum-packed and air-permeable bags of processed crawfish samples during shelf-life studies were strains of Aeromonas hydrophila and Staphylococcus aureus. C. botulinum type E and Clostridium perfringens species were not isolated from any of the uninoculated crawfish samples. Cooked crawfish were inoculated with 10(3) C. botulinum type E spores per g of crawfish tail meat to determine whether cooked crawfish tails would support the growth of C. botulinum type E strains and produce toxin at refrigerated temperatures. Spore-inoculated crawfish tails were vacuum packaged in both a high barrier film and an air-permeable bag and stored at 4 degrees C and 10 degrees C for 30 days. C. botulinum toxin E was not detected in any of the spore-inoculated packages throughout the shelf-life study until day 30. Microbiological data from this study should be useful in the development and implementation of the hazard analysis and critical control point plans for processed crawfish tails.

    Title Reduction of Endogenous Bacteria Associated with Catfish Fillets Using the Grovac Process.
    Date November 2000
    Journal Journal of Food Protection
    Excerpt

    Fresh catfish (Ictalurus punctatus) fillets are known to be contaminated with a large number of spoilage and pathogenic bacteria. The Grovac method, a new patented (U.S. 5,543,163) process, was evaluated for its efficacy in reducing the number of pathogens and spoilage microorganisms associated with food. This process involves using a processing solution containing ascorbic acid (AA) and sodium chloride (NaCl), vacuum, and tumbling. A total of 51 bacterial isolates were isolated and identified from whole catfish and catfish fillets using both selective and nonselective media, phenotypic tests, and the Vitek identification system. Psychrotrophic foodborne pathogens included: Aeromonas hydrophila, Escherichia coli, Listeria sp., Plesiomonas shigelloides, Proteus sp., Staphylococcus aureus, and Vibrio parahaemolyticus. High aerobic plate counts (2.6 x 10(7) CFU/g) for catfish fillets indicated that fillets were heavily contaminated during processing of catfish. The Grovac process showed that various treatment combinations of AA and NaCl resulted in a 1.2 to 2.3 CFU/g log reduction of microbial counts associated with catfish fillets. The effectiveness of the process may be related to the synergistic effect of tumbling, AA, NaCl, and vacuum. These results suggested that the Grovac process could be used as an alternative processing procedure to reduce microbial populations associated with catfish fillets and may be useful to improve the shelf-life and food safety of the product. Microbiological data from this study will be used for the development of a hazard analysis for the implementation of the hazard analysis critical control point program for processed catfish fillets.

    Title A Case of Acute Colonic Pseudoobstruction in Pregnancy.
    Date January 1997
    Journal The Australian & New Zealand Journal of Obstetrics & Gynaecology
    Title Inhibition of Psychrotrophic Organisms by Propionicin Plg-1, a Bacteriocin Produced by Propionibacterium Thoenii.
    Date August 1993
    Journal Journal of Dairy Science
    Excerpt

    Propionibacterium thoenii strain P127, which produces the bacteriocin propionicin PLG-1, was grown in a skim milk medium and produced bacteriocin in that medium. No bacteriocin activity was detected in skim milk medium in which strain P127-1, a bacteriocin-negative variant of strain P127, had been grown. Five psychrotrophic spoilage or pathogenic organisms (one strain each of Listeria monocytogenes, Pseudomonas fluorescens, Vibrio parahaemolyticus, Yersinia enterocolitica, and one strain of Corynebacterium sp.) were incubated for 24 h in laboratory medium, nonfermented skim milk, and skim milk that had been fermented by strain P127 or P127-1. Strains were inhibited only in the skim milk fermented by strain P127, as evidenced by loss in numbers of viable cells after 24 h at 10 degrees C and less growth than in other media after 24 h at optimal growth temperatures. Growth of selected strains was delayed or slowed during prolonged incubation (21 d) at 10 degrees C. Propionicin PLG-1 shows promise as a preservative for food products.

    Title Isolation and Purification of Propionicin Plg-1, a Bacteriocin Produced by a Strain of Propionibacterium Thoenii.
    Date March 1993
    Journal Applied and Environmental Microbiology
    Excerpt

    Production of propionicin PLG-1 by Propionibacterium thoenii P127 was pH dependent, with maximal activity detected in supernatants of cultures grown at pH 7.0 Propionicin PLG-1 was purified by ion-exchange chromatography and isoelectric focusing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of propionicin PLG-1 purified through isoelectric focusing resolved a protein band with a molecular weight of 10,000. Propionicin PLG-1 was bactericidal to sensitive cells, demonstrating single-hit kinetics. The producing strain harbored a single plasmid (pLG1) with an approximate size of 250 kb. Preliminary data indicate that both propionicin PLG-1 and immunity to the bacteriocin are encoded on the chromosome. Exposure of strain P127 to acriflavine or to N-methyl-N'-nitro-N-nitrosoguanidine yielded isolates that no longer produced bacteriocin activity and isolates that were cured of the plasmid. However, loss of bacteriocin production was not correlated with loss of the plasmid. Isolates cured of the plasmid were phenotypically identical to plasmid-bearing cells in fermentation patterns, pigment production, and growth characteristics.

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