Search PubMed⌕ Search

Biomedical subjects

S Ghosh

Publications and source records attributed to S Ghosh.

At least 937 records · Page 52Linked to original sources
PubMed1984

Aldose metabolism in developing human fetal brain and liver.

Aldose reductase, sorbitol dehydrogenase, and glucose-6-phosphate dehydrogenase enzyme activities were studied in human foetal brain and liver at different periods of gestation. Aldose reductase activity in liver disappears after 16 weeks of gestation whereas sorbitol dehydrogenase keeps on increasing in liver as well as in brain. In utero, some glucose metabolism may be mediated through an active sorbitol pathway in human fetuses.

Aldehyde Reductase↗
PubMed1984

Occurrence of polyploidy and multinuclearity in the differentiating liver of chick embryo.

Increase in nuclear size in liver has been used as an index of polyploidy. It has long been considered that the occurrence of polyploidy and multinuclearity are characteristics of mammalian liver. The present study shows the occurrence of these phenomena in the liver of birds, so these features are not confined to mammals. 3 classes of nuclear size groups have been identified. The simultaneous occurrence of polyploidy and binuclearity indicates some sort of interrelationship between them.

Animals↗
PubMed1984

Synchronous DNA synthesis and mitosis in multinucleate cells with one chromosome in each nucleus.

Multinucleate cells were induced by colcemid treatment in PtK1 cells in culture. DNA synthesis and mitotic behavior of those cells in which each nucleus contained a single chromosome were studied. More than 80% of such cells showed synchronous DNA synthesis and mitosis in all nuclei. As these genetically different nuclei respond identically to the molecules that initiate DNA synthesis and mitosis, intranuclear control of initiation of DNA synthesis and induction of mitosis by genes on individual chromosomes can be excluded. The occasional occurrence of asynchronous division in multinucleate cells is assumed to result from unequal availability of the inducer molecules to the individual nuclei.

Cell Nucleus↗
PubMed1984

Events associated with the initiation of mitosis in fused multinucleate HeLa cells.

Large multinucleate (LMN) HeLa cells with more than 10-50 nuclei were produced by random fusion with polyethylene glycol. The number of nuclei in a particular stage of the cell cycle at the time of fusion was proportionate to the duration of the phase relative to the total cell cycle. The fused cells did not gain generation time. Interaction of various nuclei in these cells has been observed. The nuclei initially belonging to the G1- or S-phase required a much longer time to complete DNA synthesis than in mononucleate cells. Some of the cells reached mitosis 15 h after fusion, whereas others required 24 h. The cells dividing early, contained a larger number of initially early G1-phase nuclei than those cells dividing late. The former very often showed prematurely condensed chromosome (PCC) groups. In cells with a large number of advanced nuclei the few less advanced nuclei could enter mitosis prematurely. On the other hand, the cells having a large number of nuclei belonging initially to late S- or G2-phase took longer to reach mitosis. These nuclei have been taken out of the normal sequence and therefore failed to synthesize the mitotic factors and depended on others to supply them. Therefore the cells as a whole required a longer period to enter mitosis. Although the nuclei became synchronized at metaphase, the cells revealed a gradation in prophase progression in the different nuclei. At the ultrastructural level the effect of advanced nuclei on the less advanced ones was evident with respect to chromosome condensation and nuclear envelope breakdown. Less advanced nuclei trapped among advanced nuclei showed PCC and nuclear envelope breakdown prematurely, whereas mitotic nuclei near interphase or early prophase nuclei retained their nuclear envelopes for a much longer time. PCC is closely related to premature breakdown of the nuclear envelope. Our observations clearly indicate that chromosome condensation and nuclear envelope breakdown are two distinct events. Kinetochores with attached microtubules could be observed on prematurely condensed chromosomes. Kinetochores of fully condensed chromosomes often failed to become connected to spindle elements. This indicates that the formation of a functional spindle is distinct from the other events and may depend on different factors.

Cell Division↗
PubMed1984

Chromosome analysis of two rat tumor cell lines. Possible role of DMs and HSR in metastasis.

The rat tumor cell lines BSp73AS (AS, non-metastasizing with pronounced adherent capacities) and BSp73ASML (ASML, highly metastasizing with reduced adherent capacities) were cytogenetically investigated. The ASML cell line is reportedly derived from the AS cell line. Both lines exhibited abnormal numerical and structural chromosomal characteristics. The metastasizing ASML cells showed a higher chromosome number (modal number: 62-63) than the nonmetastasizing AS cells (modal number:48). The AS karyotype was characterized by the presence of a large metacentric marker chromosome resulting from a Robertsonian translocation (Rb 6.7). This chromosome is as such absent in ASML cells but perhaps it may be present in these cells with a major part of chromosome 7 being deleted. The most interesting feature of the ASML karyotype was the presence of double minutes (DMs) and a homogeneously staining region (HSR) at the telomeric end of chromosome 6. These were peculiar to the ASML cells, being absent in the AS cells. DMs and HSR are reported to be correlated with the resistance to various drugs and with the acquired virulence of tumor cells through gene amplification. Therefore, we assume that in the metastasizing ASML cell line the DMs and HSR were established through genetic selection and that they are probably related to the acquired metastasizing capacity of these cells.

Animals↗
PubMed1984

Ligational behavior of a novel biologically active donor toward Cu(II) and Ni(II) ions and potentiation of its antibacterial activity by chelation with metal ions.

The chelating behavior of a new multidentate ligand with tuberculostatic activity toward Cu(II) and Ni(II) ions has been studied. This ligand 3-(2-carboxyhydrazine)phenylimino-2-oximobutane(H2C POB) is found to chelate the above metal ions in both its keto and enol forms. The probable structures of all the complexes and the location of the bonding sites have been established through magnetic and spectroscopic (infrared, electronic) studies. The Cu(II) complex of the enol form exhibits subnormal magnetic moment at room temperature, indicating the probable existence of some sort of super exchange phenomenon in the system. The ligand itself and a few of its Cu(II) complexes have been found to exert powerful in vitro antibacterial activity toward some tuberculosis mycobacteria, such as Mycobacterium flae, Mycobacterium smegmatis, and Mycobacterium H37Rv.

Antitubercular Agents↗
PubMed1984

Arterial influx, efflux and tissue content of albumin in rabbits in vivo.

The uptake, in vivo, of 125I-labelled rabbit serum albumin by the thoracic intima-media of rabbits was determined at different times after single injection of the tracer. Plasma decay of radioactivity was monitored until sacrifice. Kinetic analysis of the plasma decay by a three compartment model gave the values of the fractional rates of catabolism and of transfers between intra- and two extravascular compartments. The uptake data were analysed by a similar compartmental model involving transfers between plasma and arterial tissue. kin, the fractional rate of influx into the tissue and kout, the fractional rate of efflux from the tissue were calculated by a procedure proposed earlier. The values of kin and kout (0.055 microliter X cm-2 X h-1 and 0.2 h-1), converted to proper units, are closer to the fractional rates for the slowly exchanging pool, probably representing tissues with non-fenestrated endothelium. On the basis of the model and a normal plasma level of albumin, it can be calculated that the steady state albumin content of intima-media should be about 11 micrograms X cm-2. Direct determination of arterial albumin content by electroimmunoassay gave a value consistent with this.

Animals↗
PubMed1984

Changes in the character of Factor VIII inhibitors following Factor VIII transfusion.

Factor VIII inhibitors from 4 haemophiliacs have been studied at intervals following transfusion of a factor VIII preparation with an aim to correlate their reaction kinetic and avidity with their immuno-chemical character. Post-treatment antibodies are more avid than pre-treatment antibodies and show a second order reaction while pre-treatment antibodies produce a graph of complex nature for the time course inactivation of Factor VIII. It seems that IgG3 anti VIII:C that forms a significant part of post-treatment antibody is responsible for these discrepancies.

Antibody Affinity↗
PubMed1984

Identification of a phosphoenolpyruvate:fructose 1-phosphotransferase system in Azospirillum brasilense.

An inducible phosphoenolpyruvate:fructose phosphotransferase system has been detected in Azospirillum brasilense, which requires a minimum of two components of the crude extracts for activity: (i) a soluble fraction (enzyme I) and (ii) a membrane fraction (enzyme II). The uninduced cells neither show any uptake of fructose nor express activity of either of these two enzyme fractions. C-1 of fructose is the site of phosphorylation. This phosphotransferase system does not accept glucose as a substrate for phosphorylation.

Enzyme Induction↗
PubMed1984

Analysis of three whole-arm translocations in a mouse sarcoma cell line.

Three apparently whole-arm translocation chromosomes in the mouse sarcoma 180 ascites cell line have been studied by G- and C-banding and by Hoechst staining. All three chromosomes appear to have two centromeres. Both centromeres of one, which are very close together, are likely to be active and to produce parallel separation of the chromatids. The centromeres of the other two chromosomes are well separated. One of these two centromeres may be inactive either because the kinetochore organizer has been inactivated or because the kinetochore plate has been deleted, leaving the AT-rich centromeric constituative heterochromatin intact. The possibility that these whole arm translocations arose by telomeric fusion and the molecular basis of such fusions are discussed.

Animals↗
PubMed1984

Nuclear asynchrony in multinucleate rat kangaroo cells.

Multinucleate (MN) cells were induced in PtK1 cells by colcemid treatment. A large percentage of cells developed nuclear asynchrony both in relation to DNA synthesis and mitosis within one cell cycle. Asynchrony could be traced even in metaphase and anaphase cells in which interphase nuclei, PCC of S-phase nuclei and less condensed prophase-like chromosomes could be observed along with normally condensed chromosomes. The occurrence of such abnormalities in these large MN cells may be explained on the basis of an uneven distribution of inducer molecules of DNA synthesis and mitosis due to cytoplasmic compartmentation. The less condensed form of all the chromosomes except chromosome 4 could be traced in asynchronous metaphase. The failure of the less condensed chromosomes to undergo complete condensation does not always appear to result from late entry of nuclei containing these chromosomes into G2 phase. It is likely that chromosome 4 carries gene(s) for chromosome condensation, as this chromosome itself never appears in a less condensed form. The inducers for chromosome condensation may not always be available at equal concentrations to all chromosomes located in separate nuclei, thus they may sometimes fail to undergo complete condensation before other nuclei reach the end of prophase, when the nuclear envelopes of all nuclei present in the cell break down simultaneously.

Animals↗
PubMed1983

Change in membrane lipid fluidity induced by phospholipase A activation: a mechanism of endotoxic shock.

The effects of endotoxin administration on the fluidity of dog liver plasma membranes and their relationship with changes in phospholipase A2 activity were studied. Endotoxin administration decreased the fluidity of liver plasma membranes and this decrease was reversible by phosphatidylcholine. The endotoxin-induced decrease in membrane fluidity could be mimicked by digesting control liver membranes with exogenous phospholipase A2. Endotoxin administration also increased the endogenous phospholipase A2 activity. Endotoxin in vitro had no phospholipase A2-like activity but it activated the hydrolytic activity of exogenous phospholipase A2. Based on these data, it is concluded that endotoxin administration decreased the fluidity of canine liver plasma membranes by acting through activation of phospholipase A2. The decrease in membrane lipid fluidity induced by endotoxin administration may play a significant role in the development of the pathophysiology of endotoxic shock at the cellular level.

Animals↗