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Biomedical subjects

S Bhattacharya

Publications and source records attributed to S Bhattacharya.

At least 505 records · Page 28Linked to original sources
PubMed1986

Density of Culex vishnui and appearance of JE antibody in sentinel chicks and wild birds in relation to Japanese encephalitis cases.

In the District of Burdwan, a rural area of West Bengal State, India, Japanese encephalitis (JE) virus is endemic. In one village a longitudinal survey was conducted in order to find out whether associations could be established between the density of the vector mosquito Culex vishnui in two types of resting places, the incidence of infections in sentinel chicks exposed at monthly intervals, the prevalence of antibodies in wild birds and the occurrence of clinical infections in the human population. The experiment lasted from August 1981 till August 1982. Meteorologically a summer season (March-June), a rainy season (July-October) and a winter season (November-February) are distinguished. In the sentinel chicks infections were observed in all three seasons; in wild birds antibodies were prevalent throughout the year; these observations suggest perennial transmission of the virus in its maintenance cycle. Human infections were observed periodically with, in August 1982, a pronounced peak; this may point to fluctuations in the level of circulation of the virus in its maintenance cycle and spillover to the human population at times of peak circulation. The peaks may be related to the influx of young non-immune birds and newborn mammals into the animal population in summer. Further studies, including virus isolation attempts from mosquitoes and nestling birds, are required to prove this hypothesis.

Animals↗
PubMed1986

Humoral immune response in tuberculosis: initial characterization by immunoprecipitation of 125iodine labelled antigens and sodium dodecyl sulfate polyacrylamide gel electrophoresis.

125Iodine-labelled Mycobacterium tuberculosis antigens were immunoprecipitated with tuberculosis patients' sera and analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A group of four polypeptide antigens of 55, 38, 28 and 18 kD were thus identified. The 38 and 28 kD polypeptides were the major antigens. Antibody response differed from one patient to another, both with respect to the number and quantity of antigens precipitated. Untreated patients and those undergoing treatment with antimycobacterial drugs also showed marked differences in their antibody response. Generally, immunoprecipitates from treated patients showed a larger number of antigen bands and the relative intensities of the bands was also greater. No correlation was observed between the immunoprecipitation profile and antibody titres determined by enzyme linked immunosorbent assay.

Antibodies, Bacterial↗
PubMed1985

Selective isolation of mercurated DNA by affinity chromatography on thiol matrices.

A method for isolating picomole quantities of nascent mercurated DNA from a mixture of cellular nucleic acids using affinity chromatography on thiol-agarose is described. Analysis of mercurated DNA (HgDNA) isolated in the presence of in vivo-labeled cellular RNA or in vitro-synthesized RNA showed a low level of RNA contamination, about 0.04-0.16%, in the HgDNA. Comparative binding studies on different thiol matrices showed that the efficiency of binding of HgDNA was related to the nature but not to the SH content of the matrix used. Another important parameter for binding was the structure of HgDNA. The recovery was 98% with large nascent HgDNA sedimenting at about 30 S, whereas for short pulse-labeled single-stranded HgDNA (20-50 nucleotides long), the maximum recovery was 60%. The effect of the structure of HgDNA on the binding to the thiol matrix was probed using a variety of well-defined mercurated structures obtained from phage DNA and their restriction fragments. For DNA containing one 5-mercuricytidine 5'-triphosphate (HgdCMP) residue at each 3'-end, short fragments (size range, 230-510 bp) were bound quantitatively. With larger fragments (size range, 490-1100 bp), the binding decreased progressively with increasing size. DNA fragments larger than 1060 bp did not bind to the matrix. Single-stranded DNA containing only one HgdCMP at one end did not bind to the matrix even in the size range 200-1100 nucleotides. In contrast, continuous stretches of HgdCMP residues in one strand or short stretches of HgdCMP residues at random in both strands permit quantitative binding irrespective of size.

Bacteriophages↗
PubMed1985

The effects of estradiol and triiodothyronine on protein synthesis by hepatocytes of juvenile coho salmon (Oncorhynchus kisutch).

A method was developed for studying the in vitro metabolism of radiolabeled amino acids by dispersed salmon hepatocytes. Radioactivity accumulated in trichloroacetic acid (TCA)-precipitable and -soluble fractions of cells and in TCA-precipitable fractions of incubation medium was measured. Estradiol (E2) or triiodothyronine (T3) stimulated the amount of radioactivity in the TCA-precipitable fraction of cells in a dose-dependent manner. T3 caused an increase in TCA-soluble radioactivity of cells that were incubated with [14C]serine, [14C]glycine or the nonmetabolizable amino acid [14C]cycloleucine. E2 had either no effect or caused a decrease in TCA-soluble radioactivity in cells that were incubated with [14C]serine or [14C]glycine. E2 increased TCA-soluble radioactivity in cells that were incubated with [14C]cycloleucine. E2 but not T3 caused an increase in TCA-precipitable radioactivity in the medium from incubation of hepatocytes with metabolizable radioactive amino acids. These results suggest that protein metabolism by salmon hepatocytes is stimulated by both E2 and T3 with differing kinetic patterns.

Animals↗
PubMed1985

Bioassay of fish gonadotrophin by ovarian mitochondrial cholesterol depletion.

Murrel (Channa punctatus Bloch) ovarian tissues were incubated in vitro with or without piscine gonadotrophins and then subjected to subcellular fractionation followed by nonesterified cholesterol (cholesterol) assay. Gonadotrophin from salmon (SG-G100), tilapia (TL1MS), and sturgeon (S27MS) depleted cholesterol in the mitochondrial fraction, whereas cholesterol remained unchanged in other subcellular fractions. Aminoglutethimide, an inhibitor of mitochondrial cholesterol side-chain cleavage, blocked the depletion of mitochondrial cholesterol in response to SG-G100 and murrel pituitary extract. When ovarian tissue containing [4-14C]cholesterol was challenged with SG-G100 in vitro, a dose-dependent decrease of mitochondrial [4-14C]cholesterol was observed. Increasing concentrations (1, 2, 4, 6, or 8 micrograms/incubation) of SG-G100, TL1MS, and S27MS resulted in a clear linear depletion of mitochondrial cholesterol. The slope of the dose-response curve in different individual fish was found to be distinctly uniform and parallel. The slopes of the standard curves obtained with TL1MS and S27MS were greater than that with SG-G100, indicating that tilapia and sturgeon gonadotrophins are more potent. Carp pituitary gonadotrophin content, determined by using these standard curves, showed the sensitivity and precision of this bioassay.

Aminoglutethimide↗
PubMed1985

Placental hormones as possible markers in gynaecological cancer.

Two placental hormones (human chorionic gonadotropin and human chorionic somatotropin) were assayed in serum of patients bearing a wide variety of malignant tumours. The incidences of these hormones were found to be higher among female patients. Further studies revealed that the incidence was high in patients with malignant tumours of the gonads, breast, uterus and cervix. It was shown that these hormones are the products of tumour cells and that they are released in circulation. Studies on cervix cancer suggest that they may be useful aids in following the course of therapy.

Adult↗
PubMed1984

Role of the liver in low-density-lipoprotein catabolism in the rat.

Plasma low-density-lipoprotein (LDL) kinetics and hepatic LDL uptake were studied in the rat after an intravenous pulse injection of [14C]sucrose-labelled LDL. Some 96% of injected radioactivity was associated with apoprotein B of LDL (d 1.020-1.050). The disappearance of labelled LDL from plasma was accompanied by a linear increase in the hepatic uptake of LDL, up to 12 h after injection. Oestradiol treatment lowered plasma cholesterol concentration by 58% and the intravascular pool of LDL by 78%. This was associated with a 4-fold increase in the fractional catabolic rate of LDL and a 2-fold increase in the hepatic uptake of LDL. Oestradiol treatment did not significantly change the synthesis rate of LDL; it decreased the skin and lung uptake of LDL, but increased adrenal uptake. These results suggest that the liver plays an important role in the regulation of plasma LDL concentration.

Animals↗
PubMed1984

Plasma thyroxine levels in freshwater perch: influence of season, gonadotropins, and gonadal hormones.

Plasma thyroxine (T4) of a freshwater female perch Anabas testudineus (Bloch) has been measured by specific radioimmunoassay (RIA). Monitoring of plasma T4 throughout the year showed that July to early September (spawning stage) had the highest T4 and late September to January (postspawning stage) had the lowest T4. The plasma T4 cycle was coincident with the ovarian cycle. Treatment of intact perch with salmon gonadotropin (SG-G100) or ovine LH (500 ng/100 g body wt) markedly enhanced plasma T4 levels. Ovine FSH was without any effect. Ovarian steroids, estrone and 17 beta-estradiol (100 ng/100 g body wt), also significantly augmented T4 level whereas estriol or progesterone had no such effect. There was a striking fall of plasma T4 in ovariectomized fish. The drop of T4 due to ovariectomy could not be reversed by SG-G100 but administration of estrone or 17 beta-estradiol to ovariectomized fish effectively reversed the drop of plasma T4 level. These findings suggest that gonadotropin's stimulatory effect on perch thyroid is mediated via the release of ovarian steroids.

Animals↗