PubMed Health⌕ Search

Biomedical subjects

J Chakraborty

Publications and source records attributed to J Chakraborty.

At least 163 records · Page 9Linked to original sources
PubMed1979

Variation in plasma prednisolone concentrations in renal transplant recipients given enteric-coated prednisolone.

Renal transplant recipients receiving intermittent haemodialysis and kept under normal ward conditions showed appreciable differences in plasma prednisolone concentrations after therapeutic doses of enteric-coated prednisolone tablets. This gross day-to-day variation occurred irrespective of the dosage used. Breakfast given before prednisolone tended to reduce the rate of absorption of the drug, the effect being quantitatively most pronounced with large doses. Haemodialysis had no apparent effect on the elimination of prednisolone from plasma. Such erratic blood concentrations of prednisolone as observed in these patients, possibly resulting from variable absorption, may be potentially hazardous. Hence use of enteric-coated tablets in renal transplant recipients should be viewed with caution.

Adolescent↗
PubMed1979

Intranuclear inclusion bodies in epithelial cells of human vas deferens.

Four different types of inclusion bodies were seen within the nucleus of the principal cells in segments of vas deferens from 40 fertile males: (1) electron-dense homogeneous bodies of various sizes (0.1--1.8 microns) and shapes, (2) granular bodies approximately 0.06--0.12 microns, (3) lipid inclusion bodies, and (4) less electron-dense, filamentous bodies. They were either membrane-bound or free within the nucleoplasm. Some membranous material was scattered within the nucleoplasm. The internal structure of nuclei containing these bodies differed from cell to cell. The nucleoplasm was composed either of dense granular elements or fine filamentous components. The aggregation and density of the ground nuclear material increased with increasing numbers of inclusion bodies. Very dense nuclei were in cells with typical features of degeneration. Frequently, extruded parts of cells or entire cells were seen within the lumen of the vas deferens.

Adult↗
PubMed1979

The effect of prolonged decompaction on the development of the preimplantation mouse embryo.

A rabbit antiserum to a mouse embryonal carcinoma cell line blocks compaction of cleaving mouse embryos. Cell division is not affected up to the 32-cell stage but intracellular junctions fail to develop. Removal of the antibody at this stage permits compaction to occur and a normal blastocyst develops. Prolonged decompaction beyond the 32-cell embryo results in an increasing proportion of malformed blastocysts in which trophectodermal cells predominate and functional inner cell mass (ICM) cells are reduced or absent. The relationship of compaction to the generation of ICM and trophectoderm lineages in the intact embryo is discussed.

Animals↗
PubMed1978

Prednisone or prednisolone for the treatment of chronic active hepatitis? A comparison of plasma availability.

1 The plasma availability of prednisolone after oral doses of prednisolone and its precursor, prednisone, were compared in ten normal controls and twenty-five patients with chronic active hepatitis by estimation of the area under the plasma concentration--time curve for the drug (AUC). 2 In controls, values for AUC were significantly more variable after prednisone than prednisolone, and two subjects showed markedly inefficient conversion of prednisone to prednisolone. In patients, variability was similarly wide after both preparations, but overall bioavailability after both prednisone and prednisolone was similar to that found in controls, although three patients showed subnormal values after both preparations, possibly as a result of impaired intestinal absorption. 3 Patients with biochemical and histological evidence of active hepatocellular necrosis showed evidence of impaired activation of prednisone, but this was compensated for by a decreased rate of elimination of prednisolone from the plasma. 4 It is concluded that plasma prednisolone levels will be more predictable after prednisolone than after prednisone in subjects without hepatic dysfunction. In the presence of liver disease, because of the marked variability in plasma prednisolone levels after either drug, estimation of these could be of value in those patients whose disease cannot be controlled by normal maintenance doses.

Adult↗
PubMed1977

Binding of [3H]oxytocin to cells isolated from the mammary gland of the lactating rat.

More than 90 percent of the cells isolated from the mammary gland of lactating rats with 0.1 percent collagenase were viable by dye exclusion. Myoepithelial cells comprised about one-third of the mammary cells and appeared to be morphologically intact in electron micrographs. [(3)H]Oxytocin-binding activity was localized in an enriched myoepitheial cell fraction obtained by density gradient centrifugation of the isolated cells. The amount of [(3)H] oxytocin bound at 20 degree C and pH 7.6 was proportional to the concentration of oxytocin and the number of cells, reaching a steady state by 40 min. About 0.45 fmol of oxytocin were bound per 10(6) cells. There was a single class of independent binding sites with an apparent K(d), estimated from equilibrium conditions, of 5 nM. This value agrees within experimental error with the value calculated from the ratio of reverse to forward rate constants (5.8 x 10(-4)s(-1) and 2.2 x 10(5) M(-1)s(-1), respectively), consistent with a single-step model for the interaction of oxytocin with binding sites on the cells. Erythrocytes bound only 3.5 percent of the amount of oxytocin bound by an equal number of mammary cells. Oxytocin analogues competed with [(3)H]oxytocin for binding sites in the following order: [deamino]oxytocin > [4-threonine]oxytocin > oxytocin > [O- methyltyrosine]oxytocin > [8-lysine]vasopressin; [lysine]-bradykinin and [4-proline]oxytocin were not inhibitory in the dose ranges tested. These results demonstrate that isolated mammary cells possess oxytocin receptors with properties comparable to those found in broken mammary cell preparations.

Animals↗
PubMed1977

Characterization of oxytocin receptors in the uterus and mammary gland.

High affinity binding sites for 3[H] oxytocin have been demonstrated in particulate fractions from rat uterus and oviduct, myometrium from the sow, ewe and human, ewe endometrium, and mammary gland from the lactating rat. The binding activity has been localized to enriched plasma membrane fractions from the rat uterus and mammary gland; cells isolated from the mammary gland also bind oxytocin. The apparent dissociation constant (Kd) for the interaction of oxytocin with its binding sites in a variety of tissue preparations is in the nanomolar range. The concentration of oxytocin eliciting half-maximal contraction of the rat isolated uterus corresponds to the apparent Kd of oxytocin interaction with uterine particulate fractions. Binding is specific with respect to the target tissue or cell, as well as to the ligand. The affinity of binding sites for oxytocin analogues corresponds generally to their potencies as agonists or antagonists. Factors that affect the binding of oxytocin affect the biological response in the same way. For example, certain divalent metal ions, which increase oxytocin binding activity, enhance the sensitivity of the contractile response of the uterus and mammary gland to oxytocin. Estrogen administration, which increases the uterine binding of oxytocin, increases the sensitivity of the myometrium to oxytocin. The myometrium binds the most oxytocin at estrus and is most sensitive to oxtocin at that time. The dgree of stimulation by oxytocin of prostaglandin F2alpha synthesis by ewe endometrium is paralleled by an increased concentration of oxytocin binding sites. The marked increase in sensitivity to oxytocin of the rat uterus occurring on the day of parturition also is reflected by the amount of oxytocin bound by the uterus. Because of the many correlations between oxytocin binding and bioactivity, it appears that oxytocin binding sites on the plasma membrane of target cells constitute the recognition part of oxytocin receptors.

Animals↗
PubMed1976

Basal lamina of human seminiferous tubule- its role in material transport. I. In presence of tunica vaginal hydrocele.

Electron microscopy of testicular biopsies obtained from two adult males with tunica vaginal hydrocele revealed some protrusions from the basal lamina to the germinal epithelium in the seminiferous tubule. The protrusions were of three types: some between the spermatogonia and Sertoli cells, some directly within the Sertoli cell cytoplasm and others inside the spermatogonia. The protrusions inside the spermatogonia were only 0.5 mum deep whereas the other types were from 1-11 mum deep. Occasionally some cut off portions of these protrusions were seen inside the ground cytoplasm of the Sertoli cell without an apparent connection with the original stalk. The matrix of the protrusions contained a homogenous component (composed of a fine filamentous element) and granular and membranous components. These components closely resemble the materials found in the basal lamina of the seminiferous tubule. It has been suggested that under mild pathological conditions, i.e., hydrocele, the junctions between the seminiferous tubule epithelium and the basal lamina become somewhat more flexible. As a result, the protrusions become longer and a passage might be formed to allow the flow of raw materials in or out of the seminiferous tubule.

Adult↗