We have studied how the F-actin cytoskeleton is involved in establishing heterogeneous intracellular Ca2+ levels ([Ca2+]i) and organization of exocytotic machinery cultured bovine chromaffin cells. Simultaneous confocal visualization [Ca2+]i transmitted light studies showed that, following cell stimulation, maximal signal from Ca2+-sensitive fluorescent dye Fluo-3 was empty cytosolic spaces left by cytoskeletal cages. This mostly due to accumulation devoid components, as shown use...

Glucagon hormone is synthesized and released by pancreatic α-cells, one of the islet-cell types. This hormone, along with insulin, maintains blood glucose levels within physiological range. Glucose stimulates glucagon release at low concentrations (hypoglycemia). However, mechanisms involved in this secretion are still not completely clear. Here, using experimental calcium time series obtained mouse islets high conditions, we propose a model for α-cells. Our takes into account that resupply...

The organization of cytoplasm in excitable cells was a largely ignored factor when mathematical models were developed to understand intracellular calcium and secretory behavior. Here we employed combination fluorescent evanescent transmitted light microscopy explore the F-actin cytoskeletal vicinity sites cultured bovine chromaffin cells. This technique confocal show granules associated with borders cortical cages forming an intricate tridimensional network. Furthermore, overexpression...

One remarkable dynamic cell structure is the region between endoplasmic reticulum (ER) and mitochondria, termed mitochondria-associated membranes (MAM). MAMs carry out different cellular functions such as Ca <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> homeostasis lipid synthesis, which depend on an adequate distance separating ER mitochondria. A decreased has been observed in Alzheimer's disease, Parkinson's during cancer treatment....

Mitochondria play a significant role in shaping cytosolic Ca 2+ signals. Thus, transfer of across the mitochondrial membrane is much studied, not only intact cells but also artificial systems such as suspensions or permeabilised cells. Observed rates changes vary by at least one order magnitude. In this work, we investigate relationship between dynamics observed various experimental conditions using computational model calibrated on data. Results confirm that exchange fluxes through...

In pancreatic α-cells, intracellular Ca2+ ([Ca2+]i) acts as a trigger for secretion of glucagon, hormone that plays key role in blood glucose homeostasis. Intracellular dynamics these cells are governed by the electrical activity voltage-gated ion channels, among which ATP-sensitive K+ (KATP) channels play crucial role. majority global response to lowering external occurs form oscillations much slower than activity. These highly variable far inter-spike intervals, shapes and amplitudes...

This work introduces MACACO, a macroscopic calcium currents simulator. It provides parameter-sweep framework which computes Ca 2+ from the individual aggregation of unitary currents, using stochastic model for L-type channels. MACACO uses simplified 3-state Markov to simulate response each channel different voltage inputs cell. In order provide an accurate systematic view nature channels, is composed experiment generator, central simulation engine and post-processing script component. Due...

Pancreatic alpha cells synthesize and release glucagon. This hormone along with insulin, preserves blood glucose levels within a physiological range. During low levels, exhibit electrical activity related to glucagon secretion. In this paper, we introduce minimal state models for those ionic channels involved in mice cells. For estimation of model parameters, use Monte Carlo algorithms fit steady-state channel currents. Then, simulate dynamic currents following experimental protocols. Our...

Hydroxyapatite is the inorganic component of human bones. To be used for bone replacements, hydroxyapatite can synthesized or extracted from natural components. In this work we present extraction fish scales same Orechromis family (Tilapia) but two different species usually consumed in Mexico and Spain. Our results indicate, both species, that it possible to obtain hydroxyapatite, moreover, biomaterial enriched with magnesium Mexican Oreochromis hunteri, aluminum Spanish niloticus.

Abstract Type I collagen is a high-value polymer found naturally in animal species and with many applications the biomedical field. Collagen frequently obtained from bovine tendons, but this source presents risk of disease transmission, thus marine becoming an alternative valuable material. In present work, we report successful extraction characterization natural scales Biajaiba, highly consumed fish native to Gulf Mexico. We acid- pepsin-soluble type collagens high denaturation...

We present a stochastic simulation of L-type Ca/sup 2+/ current assuming thousands calcium channels on the membrane spherical cell. propose three-state Markov model to simulate individual contribution each channel. Rather than using statistical approximation, we actually consider channel transitions between states and evaluate unitary current. compare this aggregated contributions with simulated whole cell currents, both in response depolarising voltage pulse. On computational side, have...

Minimal mathematical models were developed to describe the electrophysiological properties of human δ-cells. Markov single channels first based on analysis data. Monte Carlo simulations voltage-clamp experiments performed in an iteratively optimization procedure estimate number required reproduce main characteristics macroscopic currents recorded experimentally. A membrane model firing action potentials was then kinetic schemes and estimated. We showed that δ-cells can be reproduced by...

This work provides a comparative report on intrinsic parallel programming (IPP) methodologies: Structured, Descriptive, and Component-based. Its main objective is lo develop an aid for programmers that will allow them to select suitable tools which enable construct hardware-independent application programs. It true every problem addressed using methods does not necessarily employ IPP methodologies. Nonwithstanding, however, the hardware-independence of makes particularly software development...

We simulate the behaviour of Na/sup +/-Ca/sup ++/ exchanger as a permanent regulator calcium homeostasis. As consequence membrane potential or concentration change, we numerically evaluate participation this in returning to equilibrium cellular conditions. In our model, is supposed work joined other important regulation mechanisms such pump, channels, buffers and passive diffusion calcium, described past work. For evaluating latter parameter, are using previously reported homogenous...

2 pages.-- Poster presentation from Eighteenth Annual Computational Neuroscience Meeting: CNS*2009 Berlin, Germany. 18–23 July 2009

The heteromeric assembly of α3 and β4 subunits acetylcholine nicotinic receptors (nAChRs) seems to mediate the secretory response in bovine chromaffin cells. However, there is no information about localization these nAChRs relationship with active zones this cellular model. present work presents first evidence that, fact, a population associated through F-actin cytoskeleton exocytotic machinery components, as detected by SNAP-25 labeling. Furthermore, we also prove upon stimulation,...