Biomedical subjects

P K Tapaswi

Publications and source records attributed to P K Tapaswi.

15 recordsLinked to original sources

PubMed1999

Dynamics of Japanese encephalitis--a study in mathematical epidemiology.

An S-->I-->R-->S (susceptible-infective-recovered-susceptible) epidemiological model coupling the dynamics of the spread of Japanese encephalitis (JE) in two populations, human and reservoir animals (pigs, cattle, equines, birds, etc.) through a vector population (a particular species of mosquitos, Culex vishnui, Culex tritaeniorhynchus, etc.) is discussed. We assume that there is a constant recruitment rate of the susceptibles into both the populations, whereas the death rates are proportional to the population sizes, which are hence variables. We also assume that the human population is regulated by the disease. Conditions for the existence of a unique endemic equilibrium were found, and the endemicity of the disease is discussed. The threshold values determine whether the disease dies out or approaches an endemic equilibrium. The persistence of disease and disease-related death can lead to a new equilibrium population size. The criteria for eradication of the disease have been worked out. The analytical results corresponding to the solutions of our system are verified by numerical analysis and computer simulation. The dynamics of disease transmission of JE during 1948-1956 in Japan were also investigated with the help of available data.

Animals↗

PubMed1998

A delay differential equations model of plankton allelopathy.

In this paper we have studied the dynamics of planktonic growth with special consideration on time dependent fluctuations in density of the species. We propose a modified delay differential equation model of the growth of two species of plankton having competitive and allelopathic effects on each other. The model system shows a stable limit cycle oscillation when the allelopathic effect is of a stimulatory nature.

Animals↗

PubMed1995

Biochemical, neuropathological and behavioral studies in hens induced by acute exposure of tri-ortho-cresyl phosphate.

A "hen model" or organophosphorus induced delayed neuropathy (OPIDN) has been developed using white leghorn exposed acutely to one of five dosages of tri-ortho-cresyl phosphate (TOCP), between 300 to 700 mg/Kg. Neuropathy target esterase was studied in brain and peripheral nerve 24 and 48 hrs following exposure. Behavioral symptoms abnormality was assessed from days 1 through 20 after exposure using a 7 point rating scale and neuropathological examination was conducted on sample collected from animals on days 0, 7, 14 and 21. Neuropathological abnormalities were indicated by damage scores between 0 (no damage) and 4 (gliosis of brain tissue, myelin loss, appearance of axonal foci etc and more than 55% degeneration of peripheral nerve fibres). TOCP (600 and 700 mg/Kg, orally) was able to inhibit NTE more than 75% in brain and peripheral nerves. TOCP at the same dosage was also capable of resulting maximal levels of neuropathological score at 4. After exposure to doses weight loss was observed abruptly in a greater extent at the beginning leading to a change in weight gain till the end of the experiment. Behavioral signs were also dose dependent. Symptoms (gain abnormality, ataxia, paresis) were noted on the early stage of experiment. Inhibition of NTE was 65% could not be reached in hens given TOCP without causing lethality and no significant ataxia or lesions developed in those birds. Behavioral signs were also observed to be late onset. These data indicate that more than 75% inhibition of peripheral nerve NTE after 24 hr exposure was predictive of severe behavioral abnormalities and pathology in the hen whereas less peripheral NTE inhibition was indicative of less severe behavioral abnormalities and a lower score for neuropathological damage.

Animals↗

PubMed1994

Tri-ortho-cresyl phosphate induced neurotarget esterase inhibition in brain and peripheral nerve effectively monitored by lymphocytes.

Tri-ortho-cresyl phosphate ester (TOCP: 10-100 mg/kg)--an organophosphorus compound (OP) inhibited brain, peripheral nerve and lymphocyte neurotarget esterase activities in a dose related and time-dependent manner. There was a good correlation of inhibition between brain, peripheral nerve and lymphocyte tissues taken from adult hens treated with 3 different doses of TOCP and sacrificed 24 and 48 hr after exposure. The results suggest that lymphocyte can effectively monitor OP compounds for investigating inhibition of neurotarget esterase activity in brain and peripheral nerve tissues.

Animals↗

PubMed1993

Turing structure during embryogenesis.

A non-linear reaction-diffusion model of the epigenetic system involving the synthesis and simultaneous intercellular self and cross-diffusion of the activator and inhibitor during embryogenesis has been proposed. It has been observed that the system spontaneously emerges into a stationary dissipative (Turing) structure only in the presence of positive cross-diffusion. That the stationary structure, thus evolved, has been shown to be globally asymptotically stable by using a suitable Liapunov's function.

Animals↗

PubMed1992

Formation of a regular dissipative structure: a bifurcation and non-linear analysis.

A non-linear reaction diffusion model of a negative feedback epigenetic control system is presented. The model involves synthesis of the mitotic inducing and inhibiting proteins, simultaneously with intercellular self-diffusion and cross-diffusion of the latter only. The importance of negative cross-diffusion for creating a regular dissipative structure is shown. A bifurcation analysis of the non-linear diffusive system has been performed and it is concluded that bifurcation is supercritical. Lastly, using Liapunov's direct method, it is shown that the pattern evolved by the system is globally asymptotically stable.

Cell Differentiation↗

PubMed1986