Abhay Kumar Pandey

Bisphenol A depresses compound action potential of frog sciatic nerve in vitro involving Ca2+-dependent mechanisms

Bisphenol-A (BPA), a toxic chemical from polycarbonate plastics, is known for behavioural and neural abnormalities. These neuro-behavioural changes reflect the changes in neural activity. However the effect of BPA on nerve action potential is not available. Therefore, present investigation was undertaken to study the effect of BPA on compound action potential (CAP) of frog sciatic nerve. Bundle containing small group of nerve fibres in a sciatic nerve was dissected and placed in a Perspex chamber perfused with Ringer solution. Suction electrodes were applied to the cut ends of the nerve for stimulating and recording purposes. The stimulation of one end (with supramaximal strength) produced CAP in the recording electrode. BPA (1-100 μM) decreased the amplitude and repolarization time of CAP in a concentration-dependent manner, without any alteration in latency, rise time and threshold. The decrease in amplitude was directly correlated with decrease in repolarization time (r=0.76). The BPA-induced decreases were absent in Ca(2+)-free medium or in presence of L-type Ca(2+)-channel antagonist (nifedipine/deltiazem). T and P type Ca(2+) channel antagonist (Ni(2+)) failed to block the BPA-induced responses. Pre-treatment with an Erα antagonist (tamoxifen) blocked the BPA-induced decrease in CAP parameters. These observations indicate that the BPA decreased the amplitude and repolarization time of CAP involving L-type Ca(2+)-channel dependent mechanisms. Further involvement of Erα in the modulation of Ca(2+) channels is a possibility.

Sexual Dimorphism in Ulna: An Osteometric Study from India

Determination of sex constitutes the most important element during the identification process of human skeletal remains. Several sex‐specific features of human skeleton have been exploited for sex determination with varying reliability. This study aims to obtain sexual dimorphic standards for ulnae of the north Indian population. Eight measurements were obtained on a sample of 106 ulnae (males‐80, females‐26) in the age range of 25–65 years. The sexual dimorphism index and demarking points were calculated for all the variables. The data were then subjected to stepwise and direct discriminant function analysis. The best discriminator of sex was the maximum length (84.9%) followed by radial notch width (84%). In stepwise analysis, these two variables were selected and provided an accuracy of 88.7% (M‐87.5%, F‐92.3%). The proximal end provided a classification rate of 81.1% (M‐80%, F‐84.6%) with selection of the notch length and olecranon width.