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Alternans of action potential duration has been associated with T wave alternans and the development of arrhythmias because it produces large gradients of repolarization. However, little is known about alternans dynamics in large mammalian hearts. Using optical mapping to record electrical activatio...
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As part of a 3-wk intersession workshop funded by a National Science Foundation Expeditions in Computing award, 15 undergraduate students from the City University of New York(1) collaborated on a study aimed at characterizing the voltage dynamics and arrhythmogenic behavior of cardiac cells for a br...
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To test whether hyperkalemia suppresses ventricular fibrillation (VF) by reducing the slope of the action potential duration (APD) restitution relation, we determined the effects of the extracellular K(+) concentration (K(+)](o)) (KCl] = 2.7-12 mM) on the restitution of APD and maximum upstroke velo...
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We present details of a novel bioelectric interface formed by placing microfabricated probes into insect during metamorphic growth cycles. The inserted microprobes emerge with the insect where the development of tissue around the electronics during the pupal development allows mechanically stable an...
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Non-viral gene vectors have attracted much attention recently due to setbacks with viral delivery systems. Here a new non-viral delivery system based on nanobiohybrids synthesized by the intercalation of a full gene and promoter encoding Green Fluorescent Protein (GFP) between the layers of an inorg...
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Introduction: Methods and Results: Conclusion: A colony of inbred German shepherd dogs with inherited ventricular arrhythmias has been established.The inward rectifier (IK1), the slow delayed rectifier (IKs), and the transient outward current (I(to)) were recorded from epicardial myocytes, and Ito w...
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Non-steroidal anti-inflammatory drugs (NSAIDs) contribute to gastrointestinal ulcer formation by inhibiting epithelial cell migration and mucosal restitution; however, the drug-affected signaling pathways are poorly defined. We investigated whether NSAID inhibition of intestinal epithelial migration...
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Cardiac arrhythmias are a leading cause of morbidity and mortality in many developed countries. Despite intensive investigation, the cellular mechanisms for most cardiac arrhythmias have not been clearly established. As a consequence, drug therapy for most forms of atrial and ventricular arrhythmias...
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A perspective on systems containing many action potential waves that, individually, are prone to spiral wave breakup is proposed. The perspective is based on two quantities, 'predator' and 'prey,' which we define as the fraction of the system in the excited state and in the excitable but unexcited s...
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Alternation in the duration of consecutive cardiac action potentials (electrical alternans) may precipitate conduction block and the onset of arrhythmias. Consequently, suppression of alternans using properly timed premature stimuli may be antiarrhythmic. To determine the extent to which alternans c...
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Despite recent advances in our understanding of the mechanism for ventricular fibrillation (VF), important electrophysiological aspects of the development of VF still are poorly defined. It has been suggested that the onset of VF involves the disintegration of a single spiral wave into many self-per...
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The mechanism for the reduction of the transient outward K+ current (Ito) in diseased myocardium is unknown. To identify potential mechanisms, the reduction of Ito and its subsequent restoration by norepinephrine (NE) were studied in cultured canine epicardial myocytes. After myocytes were cultured ...
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In dogs and in humans, potassium channels formed by ether-a-go-go-related gene 1 protein ERG1 (KCNH2) and KCNQ1 alpha-subunits, in association with KCNE beta-subunits, play a role in normal repolarization and may contribute to abnormal repolarization associated with long QT syndrome (LQTS). The mole...
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A series of related new models for the local dynamics of cardiac tissue is introduced. The models are based on a simple memory-like quantity that is used to determine the relationship among the durations and amplitudes of the stimulated action potentials. The first of these models produces period-do...
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Background: Hypothesis: Animals: Methods: Results: Conclusions and Clinical Importance: Lidocaine is most frequently used to treat ventricular arrhythmias. However, lidocaine may have an antiarrhythmic effect for certain supraventricular arrhythmias.We hypothesized that lidocaine would be effective ...
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Heart rate-dependent alterations in the duration of the electrically active state of cardiac cells, the action potential, are an important determinant of lethal heart rhythm disorders. The relationship between action potential duration and heart rate can be modelled as a nonlinear one-dimensional ma...
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Heterogeneity of cardiac electrical properties can lead to heart rhythm disorders. Numerical studies have shown that stimuli chosen to maximize dynamic heterogeneity terminate wave propagation. However, experimental investigations suggest that similar sequences induce fragmentation of the wave front...
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1. The transient outward potassium current (Ito) is reduced in canine epicardial myocytes during the acute stage of infection with Trypanosoma cruzi (Chagas' disease). Sympathetic nerve terminals are also destroyed during the acute stage of this disease. To test whether the reduction of Ito is relat...
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The restitution kinetics of action potential duration (APD) were investigated in paced canine Purkinje fibers (P; n = 9) and endocardial muscle (M; n = 9), in isolated, perfused canine left ventricles during ventricular fibrillation (VF; n = 4), and in endocardial muscle paced at VF cycle lengths (s...
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Ventricular arrhythmias and the proclivity for sudden death have been identified in German shepherd dogs. This disorder is inherited, and affected animals can be consistently produced from an established colony. The arrhythmias are most prevalent in young dogs between 22 and 26 weeks of age, with de...
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Objectives: Background: Methods: Results: Conclusion: The age-dependence of the development of ventricular arrhythmias was studied in German shepherd dogs with inherited ventricular arrhythmias and sudden death.A colony of German shepherd dogs has been established that exhibit inherited ventricular ...