Browse Health
Internist, Endocrinologist (diabetes, hormones)
15 years of experience
Accepting new patients

Education ?

Medical School
Escuela Autonoma De Ciencias Medicas De Centro America (1995)
Foreign school

Awards & Distinctions ?

Awards  
Patients' Choice Award (2012 - 2014)
Compassionate Doctor Recognition (2012 - 2013)
Associations
American Board of Internal Medicine

Affiliations ?

Dr. Luna is affiliated with 5 hospitals.

Hospital Affilations

Score

Rankings

  • HealthPark Medical Center-Lee Memorial
    2776 Cleveland Ave, Fort Myers, FL 33901
    • Currently 4 of 4 crosses
    Top 25%
  • Cape Coral Hospital
    636 Del Prado Blvd S, Cape Coral, FL 33990
    • Currently 4 of 4 crosses
    Top 25%
  • Gulf Coast Hospital
    13681 Doctors Way, Fort Myers, FL 33912
    • Currently 4 of 4 crosses
    Top 25%
  • Delta Regional Medical Center
    1400 E Union St, Greenville, MS 38703
    • Currently 1 of 4 crosses
  • HealthPark Medical Center
    9981 S Healthpark Dr, Fort Myers, FL 33908
  • Publications & Research

    Dr. Luna has contributed to 5 publications.
    Title Gabaergic Circuits Control Input-spike Coupling in the Piriform Cortex.
    Date September 2008
    Journal The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
    Excerpt

    Odor coding in mammals is widely believed to involve synchronized gamma frequency (30-70 Hz) oscillations in the first processing structure, the olfactory bulb. How such inputs are read in downstream cortical structures however is not known. Here we used patch-clamp recordings in rat piriform cortex slices to examine cellular mechanisms that shape how the cortex integrates inputs from bulb mitral cells. Electrical stimulation of mitral cell axons in the lateral olfactory tract (LOT) resulted in excitation of pyramidal cells (PCs), which was followed approximately 10 ms later by inhibition that was highly reproducible between trials in its onset time. This inhibition was somatic in origin and appeared to be driven through a feedforward mechanism, wherein GABAergic interneurons were directly excited by mitral cell axons. The precise inhibition affected action potential firing in PCs in two distinct ways. First, by abruptly terminating PC excitation, it limited the PC response to each EPSP to exactly one, precisely timed action potential. In addition, inhibition limited the summation of EPSPs across time, such that PCs fired action potentials in strong preference for synchronized inputs arriving in a time window of <5 ms. Both mechanisms would help ensure that PCs respond faithfully and selectively to mitral cell inputs arriving as a synchronized gamma frequency pattern.

    Title Crystallographic Studies of Xe and Kr Binding Within the Large Internal Cavity of Cytochrome Ba3 from Thermus Thermophilus: Structural Analysis and Role of Oxygen Transport Channels in the Heme-cu Oxidases.
    Date June 2008
    Journal Biochemistry
    Excerpt

    Cytochrome ba3 is a cytochrome c oxidase from the plasma membrane of Thermus thermophilus and is the preferred terminal enzyme of cellular respiration at low dioxygen tensions. Using cytochrome ba 3 crystals pressurized at varying conditions under Xe or Kr gas, and X-ray data for six crystals, we identify the relative affinities of Xe and Kr atoms for as many as seven distinct binding sites. These sites track a continuous, Y-shaped channel, 18-20 A in length, lined by hydrophobic residues, which leads from the surface of the protein where two entrance holes, representing the top of the Y, connect the bilayer to the a3-CuB center at the base of the Y. Considering the increased affinity of O2 for hydrophobic environments, the hydrophobic nature of the channel, its orientation within the bilayer, its connection to the active site, its uniform diameter, its virtually complete occupation by Xe, and its isomorphous presence in the native enzyme, we infer that the channel is a diffusion pathway for O2 into the dinuclear center of cytochrome ba3. These observations provide a basis for analyzing similar channels in other oxidases of known structure, and these structures are discussed in terms of mechanisms of O2 transport in biological systems, details of CO binding to and egress from the dinuclear center, the bifurcation of the oxygen-in and water-out pathways, and the possible role of the oxygen channel in aerobic thermophily.

    Title An Unexpected Outcome of Surface Engineering an Integral Membrane Protein: Improved Crystallization of Cytochrome Ba(3) from Thermus Thermophilus.
    Date January 2008
    Journal Acta Crystallographica. Section F, Structural Biology and Crystallization Communications
    Excerpt

    Past work has shown that it is feasible to mutate surface residues of soluble proteins and to a lesser extent membrane proteins in order to improve their crystallization behavior. Described here is a successful application of this approach to the integral membrane protein Thermus thermophilus cytochrome ba(3) oxidase. Two mutant forms of this enzyme (I-K258R and I-K258R/II-E4Q) were created in which symmetrical crystal contacts within crystals of wild-type enzyme were modified. These mutant proteins had greatly shortened crystallization times, decreasing from approximately 30 d for the wild type to 1-3 d for the mutants, and crystallization was highly reproducible. Native-like proteins crystallize in space group P4(3)2(1)2, whereas the mutant proteins crystallize in space group P4(1)2(1)2 with a different packing arrangement. Crystals of the P4(3)2(1)2 form occasionally diffracted to 2.4-2.3 A resolution following controlled dehydration, while those of the P4(1)2(1)2 form routinely diffracted to between 3.0 and 2.6 A for crystals that had been cryoprotected but not dehydrated.

    Title An Electrically Coupled Network of Skeletal Muscle in Zebrafish Distributes Synaptic Current.
    Date October 2006
    Journal The Journal of General Physiology
    Excerpt

    Fast and slow skeletal muscle types are readily distinguished in larval zebrafish on the basis of differences in location and orientation. Additionally, both muscle types are compact, rendering them amenable to in vivo patch clamp study of synaptic function. Slow muscle mediates rhythmic swimming, but it does so purely through synaptic drive, as these cells are unable to generate action potentials. Our patch clamp recordings from muscle pairs of zebrafish reveal a network of electrical coupling in slow muscle that allows sharing of synaptic current within and between segmental boundaries of the tail. The synaptic current exhibits slow kinetics (tau(decay) approximately 4 ms), which further facilitates passage through the low pass filter, a consequence of the electrically coupled network. In contrast to slow muscle, fast skeletal muscle generates action potentials to mediate the initial rapid component of the escape response. The combination of very weak electrical coupling and synaptic kinetics (tau(decay) <1 ms) too fast for the network low pass filter minimizes intercellular sharing of synaptic current in fast muscle. These differences between muscle types provide insights into the physiological role(s) of electrical coupling in skeletal muscle. First, intrasegmental coupling among slow muscle cells allows effective transfer of synaptic currents within tail segments, thereby minimizing differences in synaptic depolarization. Second, a fixed intersegmental delay in synaptic current transit, resulting from the low pass filter properties of the slow muscle network, helps coordinate the rostral-caudal wave of contraction.

    Title Persistent Electrical Coupling and Locomotory Dysfunction in the Zebrafish Mutant Shocked.
    Date November 2004
    Journal Journal of Neurophysiology
    Excerpt

    On initial formation of neuromuscular junctions, slow synaptic signals interact through an electrically coupled network of muscle cells. After the developmental onset of muscle excitability and the transition to fast synaptic responses, electrical coupling diminishes. No studies have revealed the functional importance of the electrical coupling or its precisely timed loss during development. In the mutant zebrafish shocked (sho) electrical coupling between fast muscle cells persists beyond the time that it would normally disappear in wild-type fish. Recordings from sho indicate that muscle depolarization in response to motor neuron stimulation remains slow due to the low-pass filter characteristics of the coupled network of muscle cells. Our findings suggest that the resultant prolonged muscle depolarizations contribute to the premature termination of swimming in sho and the delayed acquisition of the normally rapid touch-triggered movements. Thus the benefits of gap junctions during early synapse development likely become a liability if not inactivated by the time that muscle would normally achieve fast autonomous function.

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