A5000873284- Cardiac electrophysiology and arrhythmias
- Ion channel regulation and function
- Neuroscience and Neural Engineering
- ECG Monitoring and Analysis
- Receptor Mechanisms and Signaling
- stochastic dynamics and bifurcation
- Atrial Fibrillation Management and Outcomes
- Nonlinear Dynamics and Pattern Formation
- Iron Metabolism and Disorders
- RNA and protein synthesis mechanisms
- Protein Structure and Dynamics
- Cardiac Arrhythmias and Treatments
- Neuroscience and Neuropharmacology Research
- Cardiomyopathy and Myosin Studies
- Cardiovascular Effects of Exercise
- Porphyrin Metabolism and Disorders
- Enzyme Structure and Function
- Cardiovascular Function and Risk Factors
- Electrochemical Analysis and Applications
- Ion Channels and Receptors
- Cardiac Arrest and Resuscitation
- Heart Rate Variability and Autonomic Control
- Nitric Oxide and Endothelin Effects
- Neurological diseases and metabolism
- EEG and Brain-Computer Interfaces
University of California, Davis
2016-2025
Nagasaki University
2018-2023
Soka University
2015-2019
Soka University of America
2013-2014
Beppu Medical Center
2012
University of California, Los Angeles
2005-2011
Tokyo Institute of Technology
2010
Kitasato University
2005-2009
Rutgers New Jersey Medical School
2009
Rutgers, The State University of New Jersey
2009
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...
Spatially discordant alternans, where the action potential duration (APD) and intracellular calcium transient (Ca i ) alternate with opposite phase in different regions of tissue, is known to promote wave break reentry. However, this phenomenon not completely understood. It that alternans at cellular level can be caused by dynamical instabilities arising from either membrane voltage ( V m attributable steep APD restitution or (Ca) cycling. Here, we used a mathematical model Ca cycling,...
Excitable cells can exhibit complex patterns of oscillations, such as spiking and bursting. In cardiac cells, pathological voltage called early afterdepolarizations (EADs), have been widely observed under disease conditions, yet their dynamical mechanisms remain unknown. Here, we show that EADs are caused by Hopf homoclinic bifurcations. During period pacing, chaos always occurs at the transition from no EAD to stimulation frequency decreases, providing a distinct explanation for irregular...
The heart has intrinsic abilities to autoregulate contractile force in response mechanical load. Recent experimental studies show that cardiomyocytes have mechano-chemo-transduction (MCT) mechanisms form a closed feedback loop the excitation-Ca2+ signaling-contraction (E-C) coupling. This enables autoregulation of contraction load changes. Here, we develop first autoregulatory E-C coupling model couples electrophysiology, Ca2+ signaling, development and contraction, MCT feedback....
We investigate numerically and analytically the coupled dynamics of transmembrane voltage intracellular calcium cycling in paced cardiac cells using a detailed physiological model, its reduction to three-dimensional discrete map. The results provide theoretical framework interpret various experimentally observed modes instability ranging from electromechanically concordant discordant alternans quasiperiodic oscillations calcium.
Background Ryanodine receptors (RyR) mediate sarcoplasmic reticulum calcium (Ca 2+ ) release and influence myocyte Ca homeostasis arrhythmias. In cardiac myocytes, RyRs are found in clusters of various sizes shapes, RyR cluster size may critically normal arrhythmogenic spark wave formation. However, the actual at specific sites have never been measured physiological setting. Methods Results Here we sparks simultaneously to assess how influences leak. For small (<50), frequency is very low...
The assembly reaction of Escherichia coli ferritin A (EcFtnA) was studied using time-resolved small-angle X-ray scattering (TR-SAXS). EcFtnA forms a cagelike structure that consists 24 identical subunits and dissociates into dimers at acidic pH. dimer maintains nativelike secondary tertiary structures is able to reassemble 24-mer when the pH increased. reassembly induced by jump, followed TR-SAXS. Time-dependent changes in forward intensity gyration radius suggested existence significant...
Ion channels are often found arranged into dense clusters in the plasma membranes of excitable cells, but mechanisms underlying formation and maintenance these functional aggregates unknown. Here, we tested hypothesis that channel clustering is consequence a stochastic self-assembly process propose model by which formed regulated size. Our based on statistical analyses size distributions measured neurons, ventricular myocytes, arterial smooth muscle, heterologous all cases were described...
In this technical note we show the promise of using graphic processing units (GPUs) to accelerate simulations electrical wave propagation in cardiac tissue, one more demanding computational problems cardiology. We have found that speed two-dimensional (2D) tissue with a single commercially available GPU is about 30 times faster than 2.0 GHz Advanced Micro Devices (AMD) Opteron processor. also simulated conduction three-dimensional (3D) anatomic heart GPUs where 1.6 slower 32-central unit...
Spatially discordant alternans (SDA) of action potential duration (APD) is a phenomenon where different regions cardiac tissue exhibit an alternating sequence APD that are out-of-phase. SDA arrhythmogenic since it can induce spatial heterogeneity refractoriness, which cause wavebreak and reentry. However, the underlying mechanisms for formation not completely understood. In this paper, we present novel mechanism in case cellular instability leading to caused by intracellular calcium (Ca)...
TRPV4 (transient receptor potential vanilloid 4) channels are Ca2+-permeable that play a key role in regulating vascular tone. In arterial myocytes, opening of creates local increases Ca2+ influx, detectable optically as “TRPV4 sparklets.” sparklet activity can be enhanced by the action vasoconstrictor angiotensin II (AngII). This modulation depends on activation subcellular signaling domains comprise protein kinase C α (PKCα) bound to anchoring AKAP150. Here, we used super-resolution...
Elevated glucose increases vascular reactivity by promoting L-type Ca
Increasing sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) pump activity enhances sarcoplasmic (Ca) load, which increases both ryanodine receptor opening and driving force of Ca release flux. Both these effects promote spark formation wave propagation. However, increasing SERCA also accelerates local cytosolic decay as the front travels to next cluster, limits As a result, has biphasic effect on propensity arrhythmogenic waves, but monotonic increase frequency amplitude.Waves (SR)...