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JOURNAL OF THE MISSISSIPPI ACADEMY OF SCIENCES Volume 56 April-July 2011 Number 2-3 Editor Michelle Tucci Table of Contents University of Mississippi Medical Center Articles Associate Editor 151 Does Localized Mycocardial K Channel Opening Ken Butler ATP University of Mississippi Medical Result in Global Cardiac Instability? - Richard Center L.Summers, , Zizhuang Li, , Drew Hildebrandt . Editorial Board 158 Survey of Oral Hygiene Knowledge and Practice Among Mississippi Nursing Home Staff – Robin Howard and Maria Begonia Donna Sullivan. Jackson State University Gregorio Begonia 166 A Review of Native Vegetation Types in the Black Belt of Jackson State University Mississippi and Alabama, with Suggested Relationships Ibrahim Farah to the Catenas of Soil Series- J.J.N. Campbell and W.R. Jackson State University Seymour, Jr.. Robin Rockhold University of Mississippi Medical 185 Water Quality Studies on the Lower Mississippi River in Center Port Gibson, MS – Alex D. W. Acholonu and Michael Harris. Program Editor 190 The Phylogenetic Position Of Subfamily Ken Butler Monotropoideae (Ericaceae) Inferred From Large University of Mississippi Medical Ribosomal Subunit (26S)- Ray Neyland and Mark Center Merchant The Journal of the Mississippi Acad- emy of Sciences (ISSN 0076-9436) is published in January (annual meeting Departments abstracts), April, July, and October, by the Mississippi Academy of Sciences. 197 Completed Abstracts Members of the Academy receive the journal as part of their regular (non- 203 Member Recognition student) membership. Inquiries regarding subscriptions, availability of 207 Call for Abstracts back issues, and address changes should be addressed to The Mississippi 210 Supplementary Material for “A review of native vegetation types in Academy of Sciences, Post Office Box the Black Belt of Mississippi and Alabama, with suggested 55907, Jackson, MS 39296-5709, relationships to the catenas of soil series”: general characteristics of telephone 601-366-2995, or email- soil series, plus general interpreted relationships with topography [email protected] and presettlement vegetation. OFFICERS OF THE MISSISSIPPI ACADEMY OF SCIENCES President……………………………………………………………………………….Tina Martin President-Elect…………………………………………………………………………Ibrahim Farah Immediate Past-President…………………………………………………………… Mohamed Elasri Executive Officer…………………………………………………………………… Hamed Benghuzzi Junior Academy……………………………………………………………………… Joseph A. Cameron Directors………………………………………………………………………………Stan Smith ……………………………………………………………………………….............. Kenneth Butler …………………………………………………………………………………..…….Felicia Tardy Administrative Assistant………………………………………………………………Barbara Holmes The Mississippi Academy of Sciences recognizes the following Diamond Booth Exhibitor, 2011 Annual Meeting: 1. Base Pair, UMMC 2. School of Health Related Professions, UMMC 3. USM Graduate School 4. Department of Computer Engineering, JSU 5. DR-HELP, UMC 6. Mississippi Center for Supercomputing Research, OLE 7. College of Science and Technology, USM The Mississippi Center for Supercomputing Research (MCSR) provides free, high performance computing cycles and consulting in support of research and instruction, for all interested students, faculty, or researchers associated with any of Mississippi’s eight publicly funded institutions of higher learning. The MCSR actively supports the Mississippi Academy of Sciences with regular participation in the Mathematics, Computer Science, and Statistics Division. Please visit http://www.mcsr.olemiss.edu, email [email protected], or call 662-915-3922 to inquire about how we might support your HPC research or instructional computing projects at your university. Or, simply apply for an account today at http://www.mcsr.olemiss.edu/accounts. 150 April 2011, Vol. 56 No 2 and July 2011, Vol 55 No 3 Does Localized Myocardial KATP Channel Opening Result in Global Cardiac Instability? Richard L.Summers, MD, Zizhuang Li, MD, PhD, Drew Hildebrandt, PhD Department of Emergency Medicine, Department of Surgery, Division of Cardiothoracic Surgery Center for Excellence in Cardiovascular-Renal Research,University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216 Corresponding Author: Email: [email protected] ABSTRACT Ischemic preconditioning (IP) is a well described physiologic mechanism that protects myocardial tissues from repeated ischemic insults through KATP channel opening. Previously, this IP process has been thought to be a constrained to a local phenomenon that is mediated through indigenous biochemical adaptations. Recent evidence indicates that the cardioprotective effects of ischemic preconditioning (IP) may be systemically mediated and can influence distant tissues. However, it is uncertain if these global effects are necessary to maintain general circulatory integrity. D-Ala2-Leu5- enkephalin (DADLE), a -opioid receptor agonist, is known to induce an IP state including KATP channel opening. In this study we examined the effects of DADLE restricted to a localized segment of myocardium on overall cardiac and circulatory stability. A myocardial ischemia-reperfusion protocol was performed in pigs in which the left anterior descending coronary artery (LAD) was ligated distal to the 1st branch in order to isolate a section of myocardium. During the occlusion period, DADLE was infused into the distal LAD (D pigs). Hemodynamic data including continuous rhythm monitoring and 12 lead EKGs were collected before and after the initiation of the DADLE. Relative arrhythmia frequency and QT dispersion (QTdisp) were compared to a control group without DADLE (C pigs). In a total of 12 pigs studied (6 D pigs ; 6 C pigs), 83% of the D pigs and 17% of the C pigs developed sustained ventricular arrhythmias after the infusion period. The D pigs incurred a 116% increase in the amount of QTdisp over the preocclusion period as compared to only a 22% increase for C pigs. IP through a mechanism of KATP channel opening is cardioprotective and limits local myocardial tissue necrosis. However, when this effect is confined to a limited area of the heart, segmental delays in repolarization may produce global cardiac electrical instability. The findings of this study support recent evidence suggesting that IP is a complex process with systemic as well as local mechanisms of action. Keywords: KATP channel opening, ischemic preconditioning, QT dispersion, DADLE INTRODUCTION IP is thought to be mediated by -opioid receptor stimulation and induction of KATP channel opening Ischemic preconditioning (IP) refers to an (2,3,4). Recent studies have provided evidence that endogenous protective mechanism of the localized the cardioprotective effects of IP may be myocardial tissues to limit the damage and infarct systemically mediated, triggered by some humoral size of a subsequent ischemic event (1). It is thought compound that can influence distant tissues (1). to be induced by preceding short periods of ischemia While this compelling finding has some exciting that “precondition” the myocardial tissue through potential from a therapeutic standpoint, it also raises indigenous biochemically-mediated adaptations (1). Journal of the Mississippi Academy of Sciences 151 many new questions that are fundamental to our male or female pigs weighing 22+1 Kg. The understanding of the mechanisms of ischemic experimental protocol was approved by the preconditioning. Is this coronary effluent simply a Institutional Animal Care and Use Committee of the spillover of the local preconditioning or is this newly University of Mississippi Medical Center and discovered “action at a distance” also an important experiments were conducted according to the Guide part of the protective mechanism? From both a for the Care and Use of Laboratory Animals and the scientific and medical perspective it is important to guidelines of the Animal Welfare Act. ascertain if these global effects are necessary to Approximately 15 minutes prior to maintain general cardiac and circulatory integrity. In anesthesia, all pigs were administered atropine an effort to answer this question a porcine model (0.025mg/kg i.m.), meditomidine (0.08mg/kg i.m.), was developed in which a segment of myocardium and butorphanol (0.2mg/kg i.m.). Anesthesia was and its coronary supply could be isolated from the induced with ketamine (10mg/kg i.m.), the pigs remainder of the cardiac tissue. D-Ala2-Leu5- intubated, and anesthesia maintained with isoflurane. enkephalin (DADLE), a -opioid receptor agonist An ear vein was cannulated and saline infused at 10 known to induce a state of KATP channel opening ml/kg/hour. A femoral artery was catheterized and similar to the mechanisms of IP, was infused into the used for measuring arterial pressure, pulse pressure, distal segment of the left anterior descending artery heart rate and DP/dt and for sampling systemic (LAD) during an acute coronary occlusion to arterial blood. examine the effects on overall cardiovascular In a restricted myocardial ischemia- stability (2). IP through a mechanism of KATP reperfusion protocol, a segment of the myocardium channel opening is cardioprotective and limits local and its blood supply were isolated from the myocardial tissue necrosis. However, when this remainder of the heart by a ligation of the left effect is confined to a limited area of the heart, anterior descending coronary artery (LAD) just segmental delays in myocardial repolarization may distal to the 1st branch. In the operative procedure, produce global cardiac electrical instability.