Classical concepts of atrial fibrillation (AF) have been rooted in Moe’s multiple-wavelet hypothesis and simple cellular-automaton computer model. Recent experimental work has raised questions about the mechanism, suggesting a discrete “driver region” underlying AF. We reexplored theoretical basis for AF with 2-dimensional model 5×10-cm sheet cells realistic ionic coupling properties. Vagal actions were formulated based on patch-clamp studies acetylcholine (ACh) effects. In control, single...

The mechanisms by which Na+-channel blocking antiarrhythmic drugs terminate atrial fibrillation (AF) remain unclear. Classical "leading-circle" theory suggests that blockade should, if anything, promote re-entry. We used an ionically-based mathematical model of vagotonic AF to evaluate the effects applying pure Na+-current (I(Na)) inhibition during sustained arrhythmia. Under control conditions, was maintained 1 or 2 dominant spiral waves, with fibrillatory propagation at critical levels...

Tissue size has been considered an important determinant of atrial fibrillation (AF), but recent work questioned the critical hypothesis. Here, we use a previously developed mathematical model two-dimensional canine atrium with realistic action potential, ionic, and conduction properties to address substrate effects on maintenance fibrillatory activity. Cholinergic AF was simulated at different acetylcholine (ACh) concentrations ([ACh]) distributions, area varied 11.1-fold. Automated phase...

Propagation of an elliptic excitation wave front was studied in a two-dimensional model thin sheet cardiac muscle. The 2.5 x 10 mm consisted set 100 parallel cables coupled through regular array identical transverse resistors. membrane dynamics represented by modified Beeler-Reuter model. We defined the charging factor (CF) to represent single number proportion input current used charge locally below threshold and showed that CF is inversely correlated with time constant foot action...

Near-infrared spectroscopy (NIRS) was evaluated to trace the high hydrostatic pressure (HHP) processing and preservation temperature (4 °C vs. 20 °C) over course of a long term in vacuum-packaged Iberian dry-cured tenderloin (Iliopsoas et psoas minor). Spectra were obtained from total 298 samples, without opening package, using handheld MicroNIRTM 1700 OnSite-W microspectrophotometer (908.1 nm–1676.2 nm) (VIAVI Solutions Inc., United States). The discriminant models developed by means...

The simulation of the propagation electrical activity in a membrane-based realistic-geometry computer model ventricles human heart, using governing monodomain reaction-diffusion equation, is described. Each point represented by phase 1 Luo-Rudy membrane model, modified to represent action potentials. A separate longer duration potential was used for M cells found ventricular midwall. Cardiac fiber rotation across wall implemented via an analytic resulting spatially varying anisotropic...

Taking into account the current interest in use of food additives and their replacement with natural bioactive compounds, objective this study is to research possibilities using sweet cherry extract various percentages (2%, 6% 10%) as an ingredient for production lamb burgers. The findings reveal that addition causes acidification burgers higher weight loss during cooking. level was added burgers, darker they became more significant increase α-tocopherol content. Total antioxidant activity...

Two independent mathematical models of the electrophysiology human atrial cell have been published. Although these two are based on very similar data, they can result in some apparently contradictory findings, which fundamental importance to and pharmacology. In particular, simulations with given rise different conclusions regarding role rapidly activating sustained outward K+ current, Isus, determining action–potential duration. Different rate dependence action potential also this paper, we...

Introduction: Cardiac fibrillation is the deterioration of heart's normally well‐organized activity into one or more meandering spiral waves, which subsequently break up many wave fronts. Delivery an electric shock (defibrillation) only effective way restoring normal rhythm. This study focuses on examining whether higher degrees disorganization requires strengths to defibrillate and microscopic conductivity fluctuations favor success. Methods Results: We developed a three‐dimensional...

A thin sheet of cardiac tissue was modeled as a set resistively coupled excitable cables with membrane dynamics described by the modified Beeler Reuter model. Transverse connections have resistance R/sub n/ and are regularly distributed spacing Delta on any given cable, to provide alternating input output junctions. Flat wave longitudinal propagation corresponds along single continuous cable since all units network functionally isolated due absence transverse current flow. Overall, behavior...

Point source extracellular stimulation of a myocyte model was used to study the efficacy excitation cardiac cells, taking into account shape pulse stimulus and its time application in cycle. The modeled as small cylinder membrane (diameter 10 mu m, length 100 m) capped at both ends placed an unbounded volume conductor. A Beeler-Reuter modified for Na/sup +/ dynamics served simulate ionic current. located on axis, close (50 order generate nonlinear field ( phi /sub e/). low impedance...

Simulations of cardiac bioelectric phenomena remain a significant challenge despite continual advancements in computational machinery. Spanning large temporal and spatial ranges demands millions nodes to accurately depict geometry, comparable number timesteps capture dynamics. This study explores new hardware computing paradigm, the graphics processing unit (GPU), accelerate models, analyzes results context simulating small mammalian heart real time. The ODEs associated with membrane ionic...

Consumers are increasingly interested in healthy food and meat products with new health attributes, such as natural antioxidants dietary fibre. This study attempts to investigate the effects of using different proportions cherries (pico negro variety) a ingredient on physical-chemical sensorial characteristics burgers. The results indicated that proportion were added formulation beef burgers increased, nutritive content was modified caloric decreased. increasing addition cherry, high...

Atrial fibrillation (AF) is a common cardiac arrhythmia, but its mechanisms are incompletely understood. The identification of phase singularities (PSs) has been used to define spiral waves involved in maintaining the as well daughter wavelets. In past, PSs have often identified manually. Automated PS detection algorithms described previously, when we attempted apply previously developed algorithm experienced problems with false positives that made results difficult use directly. We...