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Biomedical subjects

R Vasudevan

Publications and source records attributed to R Vasudevan.

12 recordsLinked to original sources
PubMed1997

Coronary artery bypass grafting in immune thrombocytopenic purpura.

BACKGROUND: Reports of patients with idiopathic thrombocytopenic purpura undergoing cardiac operations are scarce and no recommendations exist regarding their management. We report 3 patients with idiopathic thrombocytopenic purpura and severe coronary artery disease who underwent uncomplicated coronary bypass grafting. METHODS: The case history of each patient with idiopathic thrombocytopenic purpura who underwent coronary artery bypass grafting and the literature were reviewed. RESULTS: All 3 patients underwent uncomplicated coronary artery bypass grafting after preoperative treatment with intravenous immunoglobulin and intraoperative platelet transfusions if needed. Prophylactic splenectomy was not performed. There was no increased incidence of bleeding complications. CONCLUSIONS: Coronary artery bypass grafting can be safely performed in patients with idiopathic thrombocytopenic purpura using conventional conduits after pretreating with immunoglobulin G and avoiding splenectomy.

Aged↗
PubMed1993

Intraoperative measurement of intraocular pressure in vitrectomized aphakic air-filled eyes using the Tono-Pen XL.

The Tono-Pen XL (Bio-Rad, Santa Ana, CA) was compared with manometer readings for intraoperative measurement of intraocular pressure (IOP) in 40 eyes of 40 consecutive patients after vitrectomy, lensectomy, and fluid-air exchange. Tono-Pen readings corresponding to manometer readings of 10, 20, 30, 40, and 50 mmHg were obtained in a masked fashion with a randomized sequence of manometer readings. A correlation was obtained between the manometer and Tono-Pen readings (r = 0.96 in emmetropic eyes and r = 0.93 in myopic eyes). The regression curve that represents the calibration curve of Tono-Pen in terms of the manometer readings for air-filled vitrectomized eyes was obtained. Any Tono-Pen reading can be easily translated into the corresponding manometer reading by referring to the curve. The Tono-Pen can therefore be effectively used to accurately determine intraoperative IOP in eyes undergoing vitrectomy, lensectomy, and fluid-air exchange.

Adolescent↗
PubMed1989

Analysis of neural dynamics and memory organization.

We analysed neural network dynamics by a Caianiello type of equation with special reference to memory organization and the corresponding synaptic connection matrix. Global analysis of the dynamics yielded only stable equilibrium configurations and no periodic solutions.

Animals↗
PubMed1982

Time-dependent barriers and first-passage times--different types of neuronal models.

To study the phenomenon of spike discharge in a single neuron, first-passage time density of the membrane potential to cross or reach the threshold value in different situations is analyzed. The neuron is taken as a leaky integrator and the inputs are due to Poisson events occurring independently. Closed solutions using the compensation method and imbedding techniques are arrived at. Using Keilson's limiting procedure, diffusion processes with boundaries are solved. To simulate the refractory period of the neuron, thresholds moving linearly or exponentially with time are considered. Very interesting Wald identities are obtained in the case of jump processes which go over to the corresponding identities for diffusion processes obtained by a limiting procedure.

Animals↗
PubMed1981

Neuronal spike trains with exponential decay.

Stochastic models for the spike discharge activity of neurons are analyzed. Model I treats only excitatory impulses occurring as Poisson events with exponential density of the jump magnitude, and, in the absence of these events, the subthreshold potential decays exponentially. A closed solution for the Laplace transform of the renewal density of the discharge is obtained by the imbedding method. Model III takes care of both excitatory and inhibitory impulses with exponential decay of the subthreshold potential between the jumps. Analytical closed solutions for the first passage problem are obtained in this care also. The mean interval time between the spikes and the stationary density of firing are obtained.

Electrophysiology↗