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N Sengupta

Publications and source records attributed to N Sengupta.

9 recordsLinked to original sources
PubMed1999

Role of DnaK in in vitro and in vivo expression of virulence factors of Vibrio cholerae.

The dnaK gene of Vibrio cholerae was cloned, sequenced, and used to construct a dnaK insertion mutant which was then used to examine the role of DnaK in expression of the major virulence factors of this important human pathogen. The central regulator of several virulence genes of V. cholerae is ToxR, a transmembrane DNA binding protein. The V. cholerae dnaK mutant grown in standard laboratory medium exhibited phenotypes characteristic of cells deficient in ToxR activity. Using Northern blot analysis and toxR transcriptional fusions, we demonstrated a reduction in expression of the toxR gene in the dnaK mutant strain together with a concomitant increase in expression of a htpG-like heat shock gene that is located immediately upstream and is divergently transcribed from toxR. This may be due to increased heat shock induction in the dnaK mutant. In vivo, however, although expression from heat shock promoters in the dnaK mutant was similar to that observed in vitro, expression of both toxR and htpG was comparable to that by the parental strain. In both strains, in vivo expression of toxR was significantly higher than that observed in vitro, but no reciprocal decrease in htpG expression was observed. These results suggest that the modulation of toxR expression in vivo may be different from that observed in vitro.

Animals↗
PubMed1981

Monoamine oxidase: studies of normal and psychiatric populations in a tropical environment.

The pattern of changes in the platelet and plasma monoamine oxidase (MAO) activities with different substrates was recorded in 75 psychiatric patients compared with 27 normal controls. The results confirm that chronic schizophrenics, manics and manic-depressives have significantly lower platelet MAO activity, while depressives show higher platelet MAO activity than controls, without affecting plasma MAO activity. No significant substrate-related differences were observed, except when tyramine was used as substrate; then acute schizophrenics showed significantly lower platelet MAO activity. The differences persist even during the treatment period. The present finding is consistent with the results previously reported and indicates that biochemically there exist no striking differences between our population and the populations reported on elsewhere in different environments.

Adult↗
PubMed1980

Platelet and erythrocyte-membrane adenosine triphosphatase activity in depressive and manic-depressive illness.

An investigation of Mg2+ and (Na+ + K+)-dependent adenosine triphosphatase (ATPase) activities in the platelet and erythrocyte membrane of 44 depressive and 44 manic-depressive patients was carried out before and during (for 3 weeks to less than 1 year) drug treatment. When compared with normal controls (n = 43), the patients showed significantly elevated enzyme activities during both the drug-free and drug treatment periods. No remarkable changes in enzyme activities were observed between the drug-free and drug treatment (even long-term drug treatment) periods. Results suggest an alteration of cell-membrane activity, which may reflect changes in (1) ATP level, (2) cationic balance, (3) membrane phospholipid, or some combination thereof.

Adenosine Triphosphatases↗
PubMedDate not supplied

Evaluating quality-adjusted life years: estimation of the health utility index (HUI2) from the SF-36.

UNLABELLED: Quality-adjusted life years (QALYs) are well recognized as a valid measure for outcomes in cost-effectiveness analyses. A summary health utility score is necessary to evaluate QALYs. The objective of this study was to predict a summary utility score (represented by the Health Utility Index [HUI2]) from scores on the SF-36. METHODS: A structural equation framework was applied to longitudinal data collected from 1992 to 1995 on a sample of patients insured by Southem California Kaiser Permanente (N = 6921). An ordinary least squares (OLS) method was used to estimate the HUI2. RESULTS: The OLS model on cross-sectional data predicted 50.5% of the observed variance in HUI2 scores. Parameter estimates of all SF-36 components showed statistical significance at the P < 0.05 level. CONCLUSIONS: Results of this study provide a quantitative link between two important measures of health status. The present model can be used to estimate health utility summary scores in studies that have collected SF-36 data.

Adult↗