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Biomedical subjects

S Ganguly

Publications and source records attributed to S Ganguly.

At least 109 records · Page 6Linked to original sources
PubMed1985

Absolute rates of globin gene transcription and mRNA formation during differentiation of cultured mouse erythroleukemia cells.

We have compared the rates of alpha- and beta-globin gene transcription with the rates of mature globin mRNA appearance in the cytoplasm during the course of chemically induced differentiation of mouse erythroleukemia cells by in vivo pulse-labeling experiments. The absolute rates for both processes were determined by simultaneously measuring incorporation into globin-specific transcripts and into the cellular nucleotide pool. The latter measurements provide a determination of the absolute rate of total RNA synthesis which declines during differentiation. Transcription from the beta major and beta minor globin genes was measured separately by hybridization to cloned DNA sequences from a region of the second intron which is highly divergent in the two genes. The results show that, during dimethyl sulfoxide-stimulated differentiation, transcription of alpha and beta major globin increases 15-25-fold, whereas beta minor globin transcription is not increased. Furthermore, in both undifferentiated and differentiated cells, the absolute rates of globin transcription are about equal to the rate of appearance of mature mRNA transcripts in the cytoplasm, indicating highly efficient processing of nuclear globin transcripts to mature mRNA before and after differentiation. The results indicate that dimethyl sulfoxide-induced accumulation of globin mRNA during differentiation is controlled almost entirely at the transcriptional level.

Animals↗
PubMed1985

Quantitation of pulmonary emboli with pulmonary cineangiography: preliminary report.

Pulmonary angiography is considered the definite method of diagnosing pulmonary emboli. It is hypothesized that pulmonary cineangiography is superior to conventional pulmonary angiography for quantitation of pulmonary emboli. The present study was undertaken to test the hypothesis. Six patients with an age range from 27 to 70 years with documented pulmonary emboli by pulmonary angiogram, had pulmonary cineangiograms. Pulmonary angiogram defined pulmonary emboli in nine major vessels in the six patients; while, pulmonary cineangiogram revealed another 10 major vessels with pulmonary emboli, which were either not detected or considered equivocal by the conventional pulmonary angiography. The pulmonary embolic score as an index of the extent of pulmonary emboli was 24 (mean 4 +/- 2.52 1SD) by the conventional pulmonary angiography, while the score was 60 (mean 10 +/- 3.22 1SD) by the pulmonary cineangiography, P less than 0.2. Thus, in cases with pulmonary emboli, pulmonary cineangiogram is superior to conventional pulmonary angiogram for the quantitation of pulmonary emboli.

Adult↗
PubMed1984

Cell cycle regulation of mouse H3 histone mRNA metabolism.

The mechanisms responsible for the periodic accumulation and decay of histone mRNA in the mammalian cell cycle were investigated in mouse erythroleukemia cells, using a cloned mouse H3 histone gene probe that hybridizes with most or all H3 transcripts. Exponentially growing cells were fractionated into cell cycle-specific stages by centrifugal elutriation, a method for purifying cells at each stage of the cycle without the use of treatments that arrest growth. Measurements of H3 histone mRNA content throughout the cell cycle show that the mRNA accumulates gradually during S phase, achieving its highest value in mid-S phase when DNA synthesis is maximal. The mRNA content then decreases as cells approach G2. These results demonstrate that the periodic synthesis of histones during S phase is due to changes in the steady-state level of histone mRNA. They are consistent with the conventional view in which histone synthesis is regulated coordinately with DNA synthesis in the cell cycle. The periodic accumulation and decay of H3 histone mRNA appear to be controlled primarily by changes in the rate of appearance of newly synthesized mRNA in the cytoplasm, determined by pulse-labeling whole cells with [3H]uridine. Measurements of H3 mRNA turnover by pulse-chase experiments with cells in S and G2 did not provide evidence for changes in the cytoplasmic stability of the mRNA during the period of its decay in late S and G2. Furthermore, transcription measurements carried out by brief pulse-labeling in vivo and by in vitro transcription in isolated nuclei indicate that the rate of H3 gene transcription changes to a much smaller extent than the steady-state levels of the mRNA or the appearance of newly synthesized mRNA in the cytoplasm. The results suggest that post-transcriptional processes make an important contribution to the periodic accumulation and decay of histone mRNA and that these processes may operate within the nucleus.

Animals↗
PubMed1982

Insulin activates a tyrosine-specific protein kinase in extracts of 3T3-L1 adipocytes and human placenta.

Insulin activates a tyrosine-specific cAMP-independent protein kinase when added directly to detergent extracts of differentiated 3T3-L1 adipocytes and humal placental membranes. The kinase is also activated by antibody to the insulin receptor and, to a lesser extent, by proinsulin. It catalyzes the phosphorylation of the 92,000-dalton component of the insulin receptor, histone, and casein; in each case, tyrosine is the principal amino acid modified. Under the conditions used to activate the kinase, insulin does not affect the rate of dephosphorylation of the receptor or of histone. The insulin-activated kinase is copurified with the human placental insulin receptor until the final elution from insulin-Sepharose. It remains to be established whether the kinase and the insulin receptor are separate molecules.

Adipose Tissue↗
PubMed1981

Purification and properties of the human placental insulin receptor.

Human placenta insulin receptor was purified 11,000-fold to near homogeneity using DEAE-cellulose chromatography and affinity chromatography on insulin-Sepharose. Approximately 200 to 300 micrograms of purified receptor were obtained from a single placenta. In solution, the native receptor is a complex (Mr = 440,000) of an acidic, multi-subunit protein with a Mr of 350,000 and bound detergent accounting for the remainder of the mass. The receptor protein is asymmetric (f/f0 = 1.4) and consists of a single Coomassie blue staining polypeptide of Mr = 135,000. In addition to the 135,000-dalton polypeptide, two smaller polypeptides of Mr = 45,000 and 90,000 were observed upon autoradiography of 125I-labeled receptor subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These two smaller polypeptides did not stain with Coomassie blue but migrated with native receptor activity on isoelectric focusing gels and were coimmunoprecipitated with the 135,000-dalton polypeptide by anti-insulin receptor antibody. The 135,000-dalton subunit was specifically labeled by 125I-insulin using the bifunctional cross-linking reagent disuccinimidyl suberate (P. F. Pilch, and M. P. Czech, (1979) J. Biol. Chem. 254, 3375-3381), suggesting that this component contains the insulin binding domain.

Binding, Competitive↗
PubMed1980

Hydrostatic mechanism in the roll-over test.

The roll-over test has been reported to predict pregnancy-induced hypertension. The arm used to record blood pressure has never been specified. Since the level of the arm with reference to the heart is of great importance in the interpretation of blood pressure, we recorded the roll-over response (blood pressure change from left lateral to supine position) first in the right and then in the left arm of 9 men and 8 nonpregnant women. In addition, blood pressure was measured simultaneously in both arms in 10 pregnant primigravidas. In the men and nonpregnant women the mean diastolic blood pressure after rolling over rose when the right arm was used and fell when the left arm was used. The difference in the roll-over response (right versus left arm) was accounted for by the hydrostatic effect produced by the vertical distance between the corresponding brachial arteries with the subject in the left lateral recumbent position. In the pregnant subjects as well, there was a difference between the roll-over response in the right versus left arm, accounted for by hydrostatic factors. However, the increase in blood pressure was greater for both arms, suggesting a real change in central blood pressure.

Adult↗
PubMed1980

Pyrogenic reactions after inadvertent infusion of endotoxin during cardiac catheterizations.

In April 1976 the attack rate of chills and fever with or without falls in blood pressure increased in association with cardiac catheterizations. Fevers were associated with coronary angiography and right and left heart catheterizations. Blood cultures were negative, and reactions did not correlate with amounts of contrast materials infused or with procedures done by a single operator. Significant numbers of Acinetobacter calcoaceticus (var. anitratus) and a Pseudomonas species were cultured from hospital-reservoir distilled water when it was flushed through a catheter before gas sterilization. This same water after ethylene oxide sterilization contained 2 x 10(5) ng/mL of endotoxin by limulus lysate test and was positive by rabbit pyrogen test. When washed reusable cardiac catheters were sterilized daily or when disposable catheters were substituted, febrile reactions ended. Pyrogenic reactions in patients undergoing cardiac catheterizations correlated with emptying retained endotoxin with injected contrast material from reused washed-sterilized catheters.

Acinetobacter↗