Search PubMed⌕ Search

Biomedical subjects

Amit Chakrabarti

Publications and source records attributed to Amit Chakrabarti.

6 recordsLinked to original sources
PubMed2005

Multiple-scattering effects on static light-scattering optical structure factor measurements.

We show that the extent and effect of multiple scattering on angularly resolved light-scattering intensity measurements, the optical structure factor, can be quantitatively described by a single parameter, the average number of scattering events along the scattering volume. This quantity is easily measured or calculated and hence provides a useful experimental indicator of multiple scattering, which is a hindrance to accurate structure factor measurements.

Journal Article↗
PubMed2005

Patterns in Mie scattering: evolution when normalized by the Rayleigh cross section.

An alternative to using the traditional scattering angle theta to describe light scattering from a uniform dielectric sphere is the dimensionless parameter qR, where R is the radius of the sphere, q = 2k sin(theta/2), and k is the wavenumber of the incident light. Simple patterns appear in the scattered intensity if qR is used in place of theta. These patterns are characterized by the envelopes approximating the scattered intensity distributions and are quantified by the phase-shift parameter rho = 2kR/m - 1/, where m is the real refractive index of the sphere. Here we find new patterns in these envelopes when the scattered intensity is normalized to the Rayleigh differential cross section. Mie scattering is found to be similar to Rayleigh scattering when p < 1 and follows simple patterns for p > 1, which evolve predictably as a function of p. These patterns allow us to present a unifying picture of the evolution of Mie scattering for changes in kR and m.

Journal Article↗
PubMed2005

Effect of chronic ethanol administration on testicular antioxidant system and steroidogenic enzyme activity in rats.

In order to find out the effect of chronic ethanol administration on testicular antioxidant system and steroidogenic enzyme activity, male rats fed with ethanol 1.6g/kg body weight per day for four weeks were studied. Besides a drastic reduction in body and testis weight, there was decrease in ascorbic acid, reduced glutathione and activities of superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase in the testicular tissue of the treated animals. Simultaneously, there was increase in lipid peroxidation and glutathione S-transferase activity. Activities of 3 beta-hydroxy steroid dehydrogenase and 17 beta-hydroxy steroid dehydrogenase were also found decreased in the treated animals. The results indicate that chronic ethanol administration resulted in increase in oxidative stress and decrease in the activities of steroidogenic enzymes in the rat testes.

17-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

Effect of exogenous lecithin on ethanol-induced testicular injuries in Wistar rats.

Infertility is well-established harmful effect in chronic alcoholism and so far, there is no effective treatment for this condition. The study was conducted to determine the effects of lecithin, a known hepatoprotective on ethanol induced testicular injuries in male albino rats of Wistar strain. Five groups (n=6) of animals were used. Group I served as control. Group II received daily 1.6 g ethanol/kg body weight/day for 4 weeks orally. Group III received 1.6 g ethanol + 500 mg lecithin/kg body weight/day for four weeks orally. Group IV received 1.6 g ethanol/kg body weight for/day 4 weeks and followed by 500 mg lecithin/kg body weight/ day for four weeks orally. Group V received 1.6 g ethanol/kg body weight/ day orally for 4 weeks, followed by 4 weeks abstinence. Twenty-four hours after the last treatment the rats were sacrificed using anesthetic ether. Testes were removed and used for the estimation of extent of lipid peroxidation and tissue levels of antioxidants and steroidogenic enzymes. Lecithin protected testes from ethanol induced oxidative stress. However, the drug did not show any considerable effect on the activities of testicular delta5, 3beta-HSD and 17beta-HSD. In conclusion, ethanol induced oxidative stress can be reversed by treatment with lecithin. However the effect of lecithin on steroidogenesis was not promising.

Animals↗
PubMedDate not supplied

Alcohol abuse-duration dependent decrease in plasma testosterone and antioxidants in males.

Ethanol is a testicular toxin and it causes fertility abnormalities with low sperm count and impaired sperm motility in men. The present study was designed to investigate plasma testosterone level and hypothalamic pituitary gonadal (HPG) axis function in alcoholic men and also effect of ethanol on systemic oxidative stress. Forty six male alcohol abusers in the age group 20-40 years were selected. Fifty five, males in the same age group served as control. Alcohol abusers had significantly low plasma testosterone with low luteinizing hormone and follicle stimulating hormone. In addition they had significantly high thiobarbituric acid reactive substances (TBARS), superoxide dismutase and glutathione S-transferase, and low glutathione, ascorbic acid, catalase, glutathione reductase and glutathione peroxidase. Moreover, serum testosterone level in alcoholics negatively correlated with duration of alcohol abuse, and TBARS. Duration dependent decreased serum testosterone level in alcohol abusers might be due to 1) increased oxidative stress which can damage Leydig and supporting Sertoli cells and 2) impaired HPG axis.

Adult↗