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Biomedical subjects

B Roy

Publications and source records attributed to B Roy.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Decreased response to vasopressin in the mesenteric resistance arteries of pregnant rats: effects of nifedipine and Bay K 8644.

OBJECTIVE: The purpose of this study was to investigate the contribution of potential-operated calcium (POC) channels in the mechanisms of the blunted effects of vasoconstrictors on mesenteric resistance arteries during normal pregnancy. METHODS: Mesenteric resistance arteries of virgin and term pregnant rats were set up under optimum passive tension in wire myograph systems. Cumulative concentration-response curves of arginine8-vasopressin (AVP) were measured in the absence and presence of nifedipine or Bay K 8644, a blocker and an activator, respectively, of POC channels. Binding studies were performed on membrane preparations of the mesenteric vascular bed of both groups of rats using saturation with [3H]nitrendipine. RESULTS: The maximal response to AVP was statistically similar in the two groups of arteries. Pregnancy shifted the AVP concentration-response curves to the right. Nifedipine (1 mumol/L) similarly reduced the maximum response to AVP in arteries of both groups, but produced a larger increase in EC50, the concentration inducing 50% maximum response, in resistance arteries of virgin versus pregnant rats. Bay K 8644 did not affect the maximum tension reached with AVP. However, it increased the effects of small concentrations of AVP in arteries of both groups. This was more important in tissues of virgin than pregnant rats. Binding of [3H]nitrendipine to membrane preparations of mesenteric vessels was not modified by pregnancy. CONCLUSION: Our results suggest a reduced functional influence of POC channels in the myotropic effects of AVP on mesenteric resistance arteries in pregnancy. This decreased influence of POC channels may contribute to resistance of the vasculature to vasopressor agents during pregnancy.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMedDate not supplied

A sensitive neutron dosimeter using superheated liquid.

The present work relates to a sensitive neutron dosimeter, a device for monitoring neutron dose in some accelerator and reactor sites. This device is capable of measuring a neutron dose as small as 0.1 microSv using superheated liquid as a sensitive liquid. The nucleation was measured by the volumetric method developed in our laboratory. The dose response of superheated drops of four liquids having boiling points of 8.92, -29.79, -40.75 and -45.6 degrees C, irradiated by a 3 Ci Am-Be neutron source has also been presented in this article.

Chlorofluorocarbons, Methane↗
PubMedDate not supplied

Human-specific insertion/deletion polymorphisms in Indian populations and their possible evolutionary implications.

DNA samples from 396 unrelated individuals belonging to 14 ethnic populations of India, inhabiting various geographical locations and occupying various positions in the socio-cultural hierarchy, were analysed in respect of 8 human-specific polymorphic insertion/deletion loci. All loci, except Alu CD4, were found to be highly polymorphic in all populations. The levels of average heterozygosities were found to be very high in all populations and, in most populations, also higher than those predicted by the island model of population structure. The coefficient of gene differentiation among Indian populations was found to be higher than populations in most other global regions, except Africa. These results are discussed in the light of two possible scenarios of evolution of Indian populations in the broader context of human evolution.

Alleles↗
PubMedDate not supplied

Thionucleotides as inhibitors of ribonucleotide reductase.

Ribonucleosides and xylonucleosides bearing a disulfide function on the sugar ring were synthesized. Ribonucleosides belonging to the cytidine series were found to efficiently reduce dNTP pools in the human lymphoblastoid CEM/SS cell line.

Cytidine↗
PubMedDate not supplied

Hepatic manifestations in chronic arsenic toxicity.

OBJECTIVE: The hepatotoxic action of arsenic, when used as a therapeutic agent, has long been recognized. Data on liver involvement following chronic exposure to arsenic-contaminated water are scanty. We report the nature and degree of liver involvement on the basis of hospital-based and cohort follow-up studies in patients who consumed arsenic-contaminated drinking water for 1 to 15 years. METHODS: 248 patients with evidence of chronic arsenic toxicity underwent clinical and laboratory examinations including liver function tests and HBsAg status. Liver biopsy was done in 69 cases; in 29 patients, liver arsenic content was estimated by neutron activation analysis. A cohort follow up of 23 patients who took arsenic-free water for 2-12 years was also carried out. RESULTS: Hepatomegaly was present in 190 of 248 patients (76.6%). Noncirrhotic portal fibrosis (91.3%) was the predominant lesion in liver histology. The maximum arsenic content in liver was 6 mg/Kg (mean 1.46 [0.42], control value 0.16 [0.04]; p < 0.001); it was undetected in 6 of 29 samples studied. Cohort follow-up studies showed elevation of globulin in four cases and development of esophageal varices in one case. CONCLUSION: We report the largest number of patients with liver disease due to chronic arsenicosis from drinking arsenic-contaminated water. Noncirrhotic portal fibrosis is the predominant lesion in this population.

Adult↗
PubMedDate not supplied

Frequency of sex chromatin in the buccal smear of newborn females and their mothers during first six days after delivery.

The frequencies of sex chromatin in the buccal smear of the newborn females and their mothers were low on the first post-partum day and it increased gradually during the second and third day. By the fourth and fifth day it stabilized and the incidence of sex chromatin both in the mothers and the children became similar, although the frequency on the first day was significantly lower in the newborn. The incidences of pyknotic cells in the buccal smears of the newborns and their mothers were highest on day one and these declined rapidly in the following days. The significance of these findings have been discussed.

Adolescent↗
PubMedDate not supplied

Evaluation of genotoxicity of clofazimine, an antileprosy drug, in mice in vivo. III. Sister chromatid exchange analysis in bone marrow cells.

The potential genotoxicity of an antileprosy drug, clofazimine, was evaluated in mice in an in vivo model by sister chromatid exchange (SCE) analysis. Three different dose levels (4, 20 and 40 mg/kg) were tested, and the animals were treated once daily for 15 days. Sister chromatid differential staining was done by BrdU-tablet implantation and FPG technique. All the doses tested here elevated the SCE frequencies significantly and the increases showed a significant positive correlation with the doses. The results confirm our earlier findings based on metaphase analysis and micronucleus test in the same species.

Animals↗