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Biomedical subjects

S Chatterjee

Publications and source records attributed to S Chatterjee.

At least 505 records · Page 28Linked to original sources
PubMed1977

Characterization of T3 immunoreactivity release from thyroid gland in vitro a reflection of colloid droplet formation.

T3 immunoreactivity release from the thyroid gland in vitro was shown to be increased by TSH. In the present study, we sought to determine whether the T3 immunoreactivity release is an indicator of thyroid hormone secretion or due to hormone synthesis. When thyroid glands from mice were incubated with TSH, T3 immunoreactivity release was increased in parallel with intracellular colloid droplet formation in a dose related manner. When colchicine, a known inhibitor of colloid droplet formation, was added, both T3 immunoreactivity release and colloid droplet formation were inhibited, whereas MMI, an inhibitor of hormone synthesis, failed to influence both aspects. Thus T3 immunoreactivity release as a reflection of colloid droplet formation was demonstrated. The analysis of the released immunoreactivity by Sephadex column and subsequent radioimmunoassay suggested that the T3 immunoreactivity was, to a considerable extent, due to macromolecule instead of T3 itself. The effect of I- or Li+ to inhibit thyroid hormone secretion was shown to be on the step prior to, but not subsequent to, colloid droplet formation.

Animals↗
PubMed1976

Alterations in cell surface glycosphingolipids and other lipid classes of fibroblasts in familial hypercholesterolemia.

The glycosphingolipids (GSL) and other major lipid classes were studied in cultured fibroblasts from a family with familial hypercholesterolemia. The GSL content in cells grown in medium containing fetal calf serum was increased 5-fold in the homozygote and 2- to 3-fold in both heterozygous parents. Cell surface labeling experiments, using the membrane probe galactose oxidase followed by reduction with KB3H4, showed an increased incorporation of 3H by the homozygous cells into GL4 (4-fold), GM3 (2- to 3-fold), and GL3a and GD3 (1- to 2-fold); the amount of 3H incorporated by the heterozygous cells was in between that of the homozygous and normal fibroblasts. The specific radioactivity of each of the GSL, except GL2a, was lower in the mutant cells. This unlabeled pool of GSL may be buried in the membrane matrix (less exposure), or located intracellularly, or both. The phospholipids were most markedly elevated (3-fold) in homozygous cells, with a disproportionate increase in phosphatidic acid and sphingomyelin (5- to 6-fold). The content of the GSL, except GL2a, and of the phospholipids was reduced about one-half in the homozygous fibroblasts grown in lipoprotein-deficient medium for 24 hr; by 5 days the GSL content was reduced to only 1.3 times normal and phospholipids to below normal. Incubation of normal fibroblasts in lipoprotein-dificient medium 24 hr had no effect on the GSL or phospholipid content; at 5 days, there was a 50% increase in both GL3a and GL4 with a 25% increase in GM3; there was no change in the phospholipid content. These data suggest that the defective regulation of lipid metabolism in this syndrome may be more extensive than previously realized.

Adult↗
PubMed1976

Relations between the nuclear activity and the variable 3H-amino acid incorporation pattern in Amoeba proteus.

Tracer kinetic studies have revealed the existence of a variable pattern of 3H-amino acid incorporation into amoeba proteins during the early G2 phase of the cell cycle. Two peaks of incorporation of [3H]leucine were found to occur at 19 and 22 h, whereas a single peak at 17 h was noticed in the amoebae labelled with [3H]lysine. An almost 2-fold increase of the labelled amino acid incorporation occurred during the peak periods, while the other periods showed a more or less steady state of incorporation, suggesting a basal rate of synthesis at these times. In a detailed study involving the peaks and the basal incorporation period of [3H]leucine, it was shown that the removal of the nucleus or Actinomycin D treatment eliminated the peaks but the base line protein synthesis was not affected. This suggests that for the peak synthetic periods, mRNA is probably transcribed concurrently, followed by immediate translation, whereas long-life mRNA accounts for the basal synthetic activity.

Amoeba↗
PubMed1976

Biochemical changes in the corpus luteum of the cyclic hamster.

The corpora lutea (CL) of the hamster secrete progesterone on days 1 and 2 of the oestrous cycle before marked regression at pro-oestrus (day 4) virtually eliminates them from the ovary. Luteal protein and RNA reached their maximum values on day 2 and declined up to day 4. DNA was constant throughout the cycle substantiating the importance of cellular hypertrophy rather than hyperplasia in the growth of the CL. Concentrations of cholesterol and its esters were unchanged between days 1 and 3 but almost doubled in concentration on day 4. Glucose-6-phosphate dehydrogenase activity was maximal on days 2 and 4, apparently associated on these days with steroidogenesis and lipid metabolism, respectively. A significant increase in acid phosphatase activity occurred on day 3 reaching maximal values on day 4, probably accounting for the rapid regression of the CL. The maximal concentration of 3beta-hydroxysteroid dehydrogenase in CL was on day 1, with a gradual decline over the next 3 days.

Acid Phosphatase↗
PubMed1976

Testicular histology in toad (Bufo melanostictus) following prolonged heat exposure.

A quantitative study of changes in the seminiferous tubule and the measurement of Leydig cell area were performed in the testis of toads exposed to 48 degrees C for 8 days. The frequency of occurrence of stages I and II was not affected whereas stages III and IV were influenced by the exposure to heat. The number of primary spermatocytes and secondary spermatocytes in stages III and IV were significantly decreased. The spermatocytes in stages III and IV were injured in the exposed toads. The area of Leydig cells including their nuclei was also decreased in the testes of heat exposed toads. It is concluded that the exposure to high temperature may have arrested spermatogenesis and affected Leydig cell function.

Animals↗
PubMed1975

Glycosphingolipid glycosyl hydrolases and glycosidases of synchronized human KB cells.

KB cells were synchronized by a double thymidine block procedure. An investigation was made of the activities of alpha-L-fucosidase (EC 3.2.1.51), alpha-D-galactosidase (EC 3.2.1.22), beta-D-galactosidase (ec 3.2.1.23), alpha-D-glucosidase (EC 3.2.1.20), beta-D-glucosidase (EC 3.2.1.21), alpha-D-mannosidase (EC 3.2.1.24), beta-D-N-acetylgalactosaminidase (EC 3.2.1.53), and beta-D-N-acetylglucosaminidase (EC 3.2.1.52) from synchronized cultures, using appropriate artificial substrates. Ceramide glucosidase (EC 3.2.1.45) and ceramide trihexosidase levels (EC 3.2.1.47) were also investigated at various stages in the cell cycle, using appropriate glycosphingolipid substrates. Whereas each of these enzymes exhibited some activity throughout the cell cycle, peak activity (2- to 6-fold increase) occurred late in the S phase. Two molecular forms of ceramide glucosidase (optimal activity at pH 4.0 and pH 6.0) and two forms of ceramide trihexosidase (pH 4.0 and pH 7.5) were identified. Peak levels of the forms that preferred the relatively acid pH occurred earlier in the S phase of the cell cycle than those of the forms that were more active at the higher pH. The possibility that the forms with optimal activity at pH 4 are precursors of those with optimal activity at pH 6 to 7.5 is discussed. Precipitation of beta-galactosidase of synchronized KB cells with specific antibody revealed that changes in the activity of this enzyme during the cell cycle were the result of fluctuations in the amount of the enzyme.

Acetylgalactosamine↗
PubMed1975

Glycosphingolipids of human KB cells grown in monolayer, suspension, and synchronized cultures.

Studies have been carried out on the glycosphingolipids of human KB cells grown in monolayer and suspension culture, and by synchronization of the latter with a double thymidine (2mM) block. Glycosphingolipids were identified tentatively by thin layer chromatography, gas-liquid chromatography, and combined gas-liquid chromatography and mass spectrometry. The predominant gangliosides in the these cells were AcNeu-Gal-Glc-Cer and AcNeu-Gal-GalNAc-Gal-(AcNeu). Glc-Cer. Theprincipal neutral glycosphingolipids were Glc-Cer, Gal-Glc-Cer, Gal-Gal-Glc-Cer, and GalNAc-Gal-Gal-Glc-Cer. Incubation of KB cells (grown in monolayer and subsequently in suspension culture) for 48 hours with D-[1-14Clgalactose resulted in appreciable incorporation of radioactivity into all of the principal glycosphingolipids of these cells. These experiments confirmed that KB cells are capable of synthesizing their constituent glycosphingolipids. KB cells grown in suspension culture showed A 2- to 3-fold increase inthe concentration of Glc-Cer, Gal-Glc-Cer, GalNAc-Gal-Gal-Glc-Cer, and AcNeu-Gal1NAc-Gal-Gal-Glc-Cer, and AcNeu-Gal-Ga1NAcGal-(AcNeu)-Glc-Cer. Thus, the occurrence of tissue culture-dependent changes in the level of glycosphingolipids is demonstrated. Perhaps messages governing the synthesis of glycosphingolipids are translated earlier in thecell cycle under certain conditions of growth and are affected by cell-cell contact and cell adhesion.

Carbon Radioisotopes↗
PubMed1975

Comparative trial of Dexon (polyglycolic acid), collagen, and silk sutures in ophthalmic surgery.

The tissue reaction, absorption, and handling properties of Dexon synthetic absorbable sutures, which are made from polymerized hydroxyacetic acid, were compared with those of silk and collagen in 51 eye operations, consisting mainly of cataract extractions and squint corrections. There was no significant difference between the sutures as regards degree of tissue reaction. The Dexon sutures were very strong and the knots held well. The sizes used in this series were found to be a little too thick and stiff for use in micro-surgery; smaller sizes would be easier to use and still remain strong enough. The Dexon was reliably absorbed in 5 weeks on average. No serious adverse reactions were seen with any of the sutures. Dexon was as well tolerated as the control sutures but had the advantage over silk of being absorbed and over collagen of containing no foreign protein.

Absorption↗
PubMed1975

Effect of near ultraviolet and visible light on amoeba.

The near ultraviolet and visible light (VL) impinging at an intensity of 2-5 x 10(2) J s-1 m-2 for 2-5 h kills the mitotic and the early S-phase (0- to 15-min-old) amoebae. At the mid- and late S-period only a fraction of cells are killed by VL and G2 phase cells are quite resistant. Amoebae of all cell cycle stages show a delay in the first mitotic division. DNA synthesis, as measured by [3H]thymidine incorporation, is depressed in the VL-exposed early-S amoebae. A concurrent but temporary inhibition in [3H]leucine incorporation also occurs in these cells. However, no significant change in [3H]uridine incorporation has been found. To localize the site of lethal damage, nuclear transplantation studies were undertaken between the control amoebae and the amoebae treated with VL. The nucleus of a VL-exposed early S-phase cell recovers when transplanted immediately after VL exposure into an enucleate G2 cytoplasm but dies if grafted into an enucleat S-phase cytoplasm. The therapeutic effect of the G2 cytoplasm, although at a lower level, is also evident even when the treated early S-phase nucleus is implanted 20 h later, but not after 48 h, into the G2 cytoplasm. The amoeba cytoplasm shows resistance to VL-irradiation, can accept a control nucleus from any cell cycle stage, and function normally. The G2 nucleus also remains apparently unaffected to VL exposure and can survive when it is transfered to the control cytoplasm of any cell-cycle phase. All these findings are discussed in the light of the possible existence of a repair system against VL-induced damage in the G2-phase amoeba.

Amoeba↗