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Biomedical subjects

P Goyal

Publications and source records attributed to P Goyal.

14 recordsLinked to original sources
PubMed1991

In vitro effect of Phyllanthus amarus on hepatitis B virus.

To evaluate the effects of P. amarus on hepatitis B virus (HBV) antigens and HBV-DNA, initial ethanolic extract and subsequent fractions of the plants were prepared. The whole plant material was dried, powdered and extracted with alcohol and subsequently fractionated in hexane, chloroform, butanol and finally in water. All the material were tested for in vitro effects on HBsAg, HBeAg and HBV-DNA in serum samples positive for HBV antigens followed by the screening of respective antigens by Elisa. HBV-DNA was determined by molecular hybridization. The extracts were effective against HBV antigens, the butanol extract being the most potent. Further chromatographic fractions showed an enhanced activity. The active fractions inhibited the interaction between HBsAg/HBeAg and their corresponding antibodies suggesting anti-HBs, anti-HBe-like activity and also an effect on HBV-DNA.

DNA, Viral↗
PubMed1985

Periodic and nonperiodic burst responses of frog (Rana pipiens) retinal ganglion cells.

Neural activity of class 3 retinal ganglion cells was recorded in frog optic tectum, using extracellular microelectrodes. The stimuli were rectangular patches of contrast (light-on-dark or dark-on-light), applied within the previously determined receptive fields, for periods ranging from a few milliseconds to several seconds. ON and OFF responses were recorded for as long as 1 s following stimulation. Poststimulus time histograms revealed two types of responses, labeled periodic and nonperiodic bursters. The periodic bursters were characterized by periods of high activity separated by silent or near-silent intervals. The bursts occurred rhythmically with frequencies roughly between 15 and 50 Hz. Nonperiodic bursters generally showed both broad and sharp peaks in activity, but no regular periodicities. Activity profiles were flat initially, with silent periods appearing after the first few stimulus presentations, suggesting an inhibitory nature of the bursting process. The records were shown to combine the activities of several neurons. Analysis of the waveforms in real time made possible isolation of some units. In these cases, neurons exhibited a high degree of selective synchrony, i.e., the sharing of a portion of the activity profile, and notable differences at other times. These data have implications for the processing of visual information.

Action Potentials↗