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Biomedical subjects

R Chatterjee

Publications and source records attributed to R Chatterjee.

At least 127 records · Page 7Linked to original sources
PubMed1983

Theory of long-range coherence in biological systems. I. The anomalous behaviour of human erythrocytes.

In this paper, an explicit expression of the interaction potential has been obtained, based on the Fröhlich model of long-range coherence in biological cells. These theoretical expressions are used to correlate with the experimental data obtained from the light scattering and the Brownian motion for the red blood cells (human erythrocytes). The necessary conditions are derived for the formation of rouleaux in human erythrocytes in the presence of long range interactions. The kinetics of rouleaux formation in terms of the properties of the diffusion coefficient has been investigated. It is concluded that both types of experimental data can be interpreted satisfactorily by this model.

Cell Movement↗
PubMed1983

Cloning of the MspI modification enzyme. The site of modification and its effects on cleavage by MspI and HpaII.

The gene for the MspI modification enzyme from Moraxella was cloned in Escherichia coli using the plasmid vector pBR322. Selection of transformants carrying the gene was based on the resistance of the modified plasmid encoding the enzyme to cleavage by MspI. Both chromosomal and plasmid DNA were modified in the selected clones. None of the clones obtained produced the cognate restriction enzyme which suggests that in this system the genes for the restriction enzyme and methylase are not closely linked. Crude cell extracts prepared from the recombinant strains, but not the host (E. coli HB101), contain an S-adenosylmethionine-dependent methyltransferase specific for the MspI recognition site, CCGG. Production of the enzyme is 3-4-fold greater in the transformants than in the original Moraxella strain. 5-Methylcytosine was identified as the product of the reaction chromatographically. The outer cytosine of the recognition sequence, *CCGG, was shown to be the site of methylation by DNA-sequencing methods. This modification blocks cleavage by both MspI and its isoschizomer HpaII. HpaII, but not MspI, is able to cleave the unmethylated strand of a hemimethylated substrate. The relevance of these results to the use of MspI and HpaII to analyze patterns of methylation in genomic DNA is discussed.

Cloning, Molecular↗
PubMed1983

A comparison of the acid-base metabolisms of pooled human dental plaque and salivary sediment.

The acid-base metabolisms of the mixed bacteria in pooled dental plaque and salivary sediment sampled from the same subjects were compared in vitro. Plaque at a suspension concentration of 8.3 per cent (v/v) was found to produce pH responses like those of sediment at 16.7 per cent (v/v) with all substrates and under all incubation conditions tested. The substrates examined included several carbohydrates (glucose, sucrose and starch) and several nitrogenous substrates (urea, arginine and the arginine peptide glycyl-glycyl-lysyl-arginine also called sialin). Also examined were the effects of endogenous substrates and of salivary supernatant and fluoride. A difference in suspension concentration was necessary to achieve similarity in pH response which was attributed to the presence of more non-viable epithelial cells in sediment than in plaque. Under these conditions, salivary sediment showed a slightly greater buffering capacity than plaque, a difference that was not evident if salivary supernatant was present. It was clear from this study that salivary sediment and pooled dental plaque from the same subjects have similar acid-base metabolisms and that the more abundant and readily available sediment could be used to study such metabolism in dental plaque.

Arginine↗
PubMed1982

Inhibition of ovulation by indomethacin in rats.

Indomethacin, a specific prostaglandin synthetase inhibitor, was found to block ovulation in rats when scheduled at 1200h on day 4 of the cycle. The same regimen was ineffective at 1800h, but its antiovulatory efficacy was estimated to be about 50% when given at 1600h. An injection of indomethacin given concurrently with prostaglandin F2a allowed ovulation in 80% of the test animals. None of the animals, irrespective of the drug schedule, became pregnant on mating with the fertile males but showed a remarkable decidual cell reaction (DCR) in response to unilateral uterine traumatization. The anti-ovulatory or intinidation effect of indomethacin is discussed.

Animals↗
PubMed1982

Blockade of ovulation by clomiphene citrate and its reversal by human chorionic gonadotropin or prostaglandin F2 alpha in rats.

Clomiphene citrate (clomid), a nonsteroidal estrogenic compound, was found to be effective in blocking ovulation in rats when scheduled at a dose of 3.0 mg/kg on day 2 or late day 4 of the estrus cycle. Treatment with hCG or prostaglandin F2 alpha (PGF2 alpha) concurrently with clomid consistently reversed the antiovulatory effect of clomid. The possible mode of action of clomid in the interruption of ovulation has been discussed.

Animals↗
PubMed1981

Intrauterine contraceptive devices: failure of unilateral intrauterine device in inducing luteolysis in rabbits, rats and mice.

Insertion of a unilateral intrauterine device (IUD) on day 1 pc in rabbits and rats or day 2 pc in mice is found to interrupt pregnancy in the device-bearing uterine horn, but does not affect blastocyst implantation or fetal development of the contralateral side. It is also evident that following surgical ablation of the ovary of the non-IUD side, the ovary of the IUD-bearing side can effectively maintain pregnancy and fetal growth as in controls. The possible mode of action of the IUD has been discussed.

Animals↗
PubMed1981

Thioacetamide-induced hepatocarcinoma in rat.

Out of 56 thioacetamide (TAA)-fed rats hepatocellular carcinoma were found in four instances after 300, 360, 450 and 495 days in the present experiment. Of the four tumours, two showed lung metastasis. The size of TAA-treated hepatocyte nucleoli increased greatly after several weeks of feeding. Two enzymes, succinate dehydrogenase and glucose-6-phosphatase were found in both cytoplasma and nucleoli of hepatocytes of which nucleolar localizations are quite new. In hepatocellular carcinoma, malignant cells lost glucose-6-phosphatase activity completely in cytoplasm and nucleoli though succinate dehydrogenase activity was present in these organelles.

Acetamides↗
PubMed1981

Muscle ribosome detachment factor. Does it have a role in the pathogenesis of Duchenne muscular dystrophy?

A protein that detaches ribosomes from rough microsomal membranes ("detachment factor") (DF) was isolated from the cytosol fraction of rat and human muscle. The procedure of isolation included differential centrifugation, precipitation with ammonium sulfate and column chromatography with Sephadex G-100. The protein which is not completely homogenous, has a molecular weight of 50,000-60,000 daltons, is heat labile and has an optimum pH at 7.4-7.6. The DF activity of the protein is inhibited by soybean trypsin inhibitor (73%), pepstatin (67%), and leupeptin (42%), although no proteolysis could be measured. The DF activity was tested on muscle samples (rough microsomal membranes) obtained from Duchenne muscular dystrophy (DMD) patients (7 cases) and normal controls (16 cases). The yield of membrane bound ribosomes (MBR) obtained from muscle samples of DMD patients by extraction with DF is 5-fold higher than from muscle samples of normal controls. The difference in MBR yield is not related to the type of DF. Similar values for MBR were obtained with rat and human (normal and dystrophic) DF. Ribosomal protein synthesis (RPS) with ribosomes extracted by DF showed values similar to the RPS of detergent extracted ribosomes. Our findings suggest the observed increase in membrane bound ribosomes in DMD probably results from increased levels of mRNAs coding for membrane and secretory proteins such as collagen.

Amino Acids↗