A5009561014- Cardiac electrophysiology and arrhythmias
- Ion channel regulation and function
- Cardiac Arrhythmias and Treatments
- Neuroscience and Neural Engineering
- Mitochondrial Function and Pathology
- Cardiac Ischemia and Reperfusion
- Cardiac pacing and defibrillation studies
- ECG Monitoring and Analysis
- Nonlinear Dynamics and Pattern Formation
- Neuroscience and Neuropharmacology Research
- Cardiovascular Effects of Exercise
- stochastic dynamics and bifurcation
- Receptor Mechanisms and Signaling
- Electrochemical Analysis and Applications
- ATP Synthase and ATPases Research
- Cardiac Arrest and Resuscitation
- Cardiovascular Function and Risk Factors
- Protein Structure and Dynamics
- Atrial Fibrillation Management and Outcomes
- Fuel Cells and Related Materials
- Bioinformatics and Genomic Networks
- Cardiomyopathy and Myosin Studies
- Electron Spin Resonance Studies
- Advanced MRI Techniques and Applications
- Gene Regulatory Network Analysis
University of California, Los Angeles
2014-2023
Florida Department of Health
2021
UCLA Health
2005-2020
University of California System
2018
Cardiovascular Research Center
2001-2016
Indiana University – Purdue University Indianapolis
2009-2015
National Yang Ming Chiao Tung University
2002-2015
Chang Gung University
2015
Harbin Medical University
2015
First Affiliated Hospital of Harbin Medical University
2015
The Hill coefficient is commonly used to estimate the number of ligand molecules that are required bind a receptor produce functional effect. However, for with more than one binding site, equation does not reflect physically possible reaction scheme; only under very specific condition marked positive cooperativity accurately sites. best thought as an “interaction” coefficient, reflecting extent among multiple Several relatively simple, plausible schemes shown here variety dose-response curve...
The extreme sensitivity to initial conditions that chaotic systems display makes them unstable and unpredictable. Yet same also highly susceptible control, provided the developing chaos can be analyzed in real time analysis is then used make small control interventions. This strategy has been here stabilize cardiac arrhythmias induced by drug ouabain rabbit ventricle. By administering electrical stimuli heart at irregular times determined theory, arrhythmia was converted periodic beating.
Ventricular fibrillation is the leading cause of sudden cardiac death. In fibrillation, fragmented electrical waves meander erratically through heart muscle, creating disordered and ineffective contraction. Theoretical computer studies, as well recent experimental evidence, have suggested that created sustained by property restitution action potential duration (that is, its dependence on previous diastolic interval). The hypothesis states steeply sloped curves create unstable wave...
Particulate pollutants cause adverse health effects through the generation of oxidative stress. A key question is whether these are mediated by particles or their chemical compounds. In this article we show that aliphatic, aromatic, and polar organic compounds, fractionated from diesel exhaust (DEPs), exert differential toxic in RAW 264.7 cells. Cellular analyses showed quinone-enriched fraction was more potent than polycyclic aromatic hydrocarbon (PAH)–enriched O2•− generation, decrease...
In heart, glycolysis may be a preferential source of adenosine triphosphate (ATP) for membrane functions. this study the patch-clamp technique was used to potassium channels sensitive intracellular ATP levels in permeabilized ventricular myocytes. Activation these K + has been implicated marked cellular loss leading electrophysiological abnormalities and arrhythmias during myocardial ischemia. The results showed that more effective than oxidative phosphorylation preventing ATP-sensitive from...
The synchronization of coupled oscillators plays an important role in many biological systems, including the heart. In heart diseases, cardiac myocytes can exhibit abnormal electrical oscillations, such as early afterdepolarizations (EADs), which are associated with lethal arrhythmias. A key unanswered question is how cellular EADs partially synchronize tissue, required for them to propagate. Here, we present evidence, from computational simulations and experiments isolated myocytes, that...
Background —T-wave alternans, which is associated with the genesis of cardiac fibrillation, has recently been related to discordant action potential duration (APD) alternans. However, cellular electrophysiological mechanisms responsible for alternans are poorly understood. Methods and Results —We simulated a 2D sheet tissue using phase 1 Luo-Rudy model. A steep (slope >1) APD restitution curve promoted concordant T-wave without QRS When pacing was from single site, occurred only when rate...
Abstract —Sudden cardiac death resulting from ventricular fibrillation can be separated into 2 components: initiation of tachycardia and degeneration to fibrillation. Clinical drug studies such as CAST SWORD demonstrated that focusing exclusively on the first component is inadequate a therapeutic modality. The hope for developing effective pharmacological therapy rests comprehensive understanding second component, transition We summarize evidence spatiotemporal chaos, with similarities...
Spiral wave breakup is a proposed mechanism underlying the transition from ventricular tachycardia to fibrillation. We examined importance of restitution action potential duration (APD) and conduction velocity (CV) stability spiral reentry in two-dimensional sheet simulated cardiac tissue. The Luo-Rudy model was modified eliminate its properties, which are caused by deactivation or recovery inactivation K + , Ca 2+ Na currents ( I respectively). In this model, we find that 1) main...
The deduced amino acid sequence of the cardiac sarcolemmal Na(+)-Ca2+ exchanger has a region which could represent calmodulin binding site. As regions proteins often have an autoinhibitory role, synthetic peptide with this was tested for functional effects on exchange activity. inhibits Na(+)-dependent Ca2+ uptake (KI approximately 1.5 microM) and Nao(+)-dependent efflux vesicles in noncompetitive manner respect to both Na+ Ca2+. is also potent inhibitor 0.1 current excised patches. site...
The cause of altered ionic homeostasis leading to cell death during ischemia and metabolic inhibition is unclear. Hemichannels, which are precursors gap junctions, nonselective ion channels that permeable molecules less thanM r 1000. We show hemichannels open upon exposure calcium-free solutions when they either heterologously overexpressed in HEK293 cells or endogenously expressed cardiac ventricular myocytes. In the presence normal extracellular calcium, inhibition. During other forms...
In the heart, oxidative stress caused by exogenous H(2)O(2) has been shown to induce early afterdepolarizations (EADs) and triggered activity impairing Na current (I(Na)) inactivation. Because activates Ca(2+)/calmodulin kinase (CaMK)II, which also impairs I(Na) inactivation promotes EADs, we hypothesized that CaMKII activation may be an important factor in EADs stress. Using patch-clamp intracellular Ca (Ca(i)) imaging Fluo-4 AM-loaded rabbit ventricular myocytes, found exposure (0.2 1...
To investigate whether energy derived from glycolytic and oxidative metabolism are preferentially used for different functions in heart, tension, intracellular potential, extracellular [K+] pH (using triple barrel K/pH electrodes, tip diameter 0.5 mm) were monitored isolated arterially perfused rabbit interventricular septa during exposure to hypoxia metabolic inhibitors. Myocardial content of high phosphates, lactate, glycogen determined under the same conditions. Inhibiting with hypoxia,...