Biomedical subjects

Sandip Kar

Publications and source records attributed to Sandip Kar.

4 recordsLinked to original sources

PubMed2005

Sustained simultaneous glycolytic and insulin oscillations in beta-cells.

Chemical oscillation in glycolysis induced by glucose is an universal feature in all living cells. In beta-cells this is accompanied by sustained oscillations of concentration of insulin, which helps to keep the blood glucose level within optimum limits. Experiments in this regard had shown that the glycolytic and insulin oscillations are almost consistently in phase and their time periods are very close to each other at both high and low initial concentration of glucose. Experiments have also demonstrated the dynamical transition between the states of glycolytic oscillations indicating a saturation behaviour of glucose transporters at a higher glucose flow rate. We propose a phenomenological model to understand these simultaneous oscillations and how glycolysis provides a mechanism for pulsatory insulin secretion in the light of these basic experimental issues.

Adenosine Triphosphate↗

PubMed2004

Mobility-induced instability and pattern formation in a reaction-diffusion system.

Ions undergoing a reaction-diffusion process are susceptible to electric field. We show that a constant external field may induce a kind of instability on the state stabilized by diffusion in a reaction-diffusion system giving rise to formation of pattern even when the diffusion coefficients of the reactants are equal. The origin of the pattern is due to the difference in mobilities of the two species and is thus markedly different from that of deformed Turing pattern in presence of the field. While this differential flow instability had been shown earlier to result in traveling waves, we realize in the context of stationary pattern formation in a typical reaction-diffusion-advective system. Our analysis is based on a numerical simulation of a generic model on a two-dimensional domain.

Journal Article↗

PubMed2003

Collapse and revival of glycolytic oscillation.

Glycolysis is the major source of metabolic energy in almost all living cells. A key feature of the glycolytic oscillations is their critical control by substrate injection rate. We show that in the limit of weak noise of the fluctuating substrate injection rate a new instability arises in the dynamics leading to collapse and revival of glycolytic oscillation reminiscent of "bursting" of action potential in nerve cells. The dynamical system in this limit also exhibits an interesting mirror image symmetry between growth and decay of fluctuations of the reaction product.

Allosteric Regulation↗

PubMed2002

Class of self-limiting growth models in the presence of nonlinear diffusion.

The source term in a reaction-diffusion system, in general, does not involve explicit time dependence. A class of self-limiting growth models dealing with animal and tumor growth and bacterial population in a culture, on the other hand, are described by kinetics with explicit functions of time. We analyze a reaction-diffusion system to study the propagation of spatial front for these models.

Animals↗