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Biomedical subjects

S Chaudhury

Publications and source records attributed to S Chaudhury.

At least 55 records · Page 3Linked to original sources
PubMed1985

Induction of brain tubulin by triiodothyronine: dual effect of the hormone on the synthesis and turnover of the protein.

The relative effects of triiodothyronine (T3) on the synthesis and turnover of tubulin in the developing rat and chick brain have been examined. Measurements of rates of turnover of radiolabeled tubulin in the hormone-sensitive tissues show that the half-life of tubulin turnover is 4-6 h in the absence of T3 and 10-12 h in the presence of the hormone. Analysis of short-term kinetic data on the stimulation of tubulin by T3 in the chick brain show that the rapid induction is due to a dual effect of the hormone on the metabolism of tubulin--an increase in the rate of synthesis as well as a decline in its rate of turnover.

Animals↗
PubMed1983

Stimulation of tubulin synthesis by thyroid hormone in the developing rat brain.

The effect of triiodothyronine on the biogenesis of tubulin has been studied in the developing rat brain. In organ cultures of brains from newborn rats, the hormone stimulates the incorporation of [14C]leucine into tubulin by 60-80% within 2 h in the absence of any significant change in total protein synthesis. This stimulation is strictly age-dependent (only brains from late fetal or newborn rats are sensitive), dose-dependent (stimulation increases progressively and reaches a maximum level with physiological dose of the hormone) and displays tissue specificity. The temporal correspondence of the sensitivity of the rat brain to triiodothyronine with the period of normal rise in the level of tubulin and that of the maximal level of nuclear triiodothyronine receptors in the brain strongly suggests the involvement of the hormone in regulating the biogenesis of tubulin during the differentiation and maturation of neonatal rat brain.

Age Factors↗
PubMed1983

Messenger RNA for glutamine synthetase. Review article.

Of the various eucaryotic tissues, where glutamine synthetase (GS) mRNA and its regulation have been investigated, the induction of GS by glucocorticoids in the embryonic chick retina represents one of the systems most extensively studied. GS mRNA was first identified at the polysomal level by immunochemical precipitation of fractionated polysomes containing nascent GS chains with anti-GS gamma-globulin. The mRNA has been shown to be polyadenylated at the 3' end; on this basis, it has been partially purified from embryonic chick retina as well as from N. Crassa by chromatography on oligo(dT)-cellulose or poly(U)-sepharose and translated in cell-free protein synthesizing systems derived from wheat germ. Hormonal regulation of GS activity studied in the embryonic retina, hepatoma tissue culture cells, or in other tissues is always shown to be mediated by GS mRNA. In the retina, hydrocortisone (HC) elicits an age-related and transcription-dependent induction of GS by enhancing the level of GS mRNA in the polysomes through an increased supply of this mRNA from the nucleus. Comparative studies of three inhibitors of transcription, viz. actinomycin D, leucanthone and proflavine on the induction of GS by HC indicate that the latter inhibits GS mRNA selectively and reversibly with minimal effects on other RNA synthesis. Since proflavine acts by competing with HC-receptor binding sites in the nuclei, further studies on its interaction with the retina genome are likely to help identify the DNA sequences involved in the GS induction. In bacteria, studies on the genetics and physiology of various mutants with lesions in the structural gene for GS show that the transcription of the GS gene (gln A) is regulated both positively and negatively by GS and the product of another gene gln F. Purification of GS mRNA to homogeneity cloning of its cDNA and development of assay systems for cell-free transcription of GS are other studies likely to advance our knowledge on GS mRNA and its regulation.

Animals↗
PubMed1983

Modulation of tubulin synthesis by tri-iodothyronine in the embryonic chick brain.

In organ cultures of embryonic chick brain, tri-iodothyronine is shown to elicit an age-dependent stimulation of the synthesis of tubulin. In cultures of brains from 8-day embryos where the response is maximal, a 70-100% increase in the rate of synthesis of tubulin is elicited by T3 within 2 h. The stimulatory response is dose-dependent, requires transcription, and is temporally coincident with the early phase of the normal ontogenic rise in level of tubulin and of intense neuronal differentiation in the embryonic chick brain. The overall results indicate the involvement of T3 in regulating the biogenesis of tubulin in the developing brain.

Animals↗
PubMed1981

Multiple drug therapy--a comparative study with 2 tier and 3 tier combination of rifampicin, clofazimine, DDS, INAH and thiacetazone in lepromatous cases.

A comparative study with 2 tier and 3 tier combination of Rifampicin, Clofazimine, DDS, INAH and Thiacetazone was conducted on fifty lepromatous leprosy cases for varying periods. Assessment showed that 2 tier combination of clofazimine and DDS produced good results but the cost stood in the way; whereas 3 tier combination of DDS, thiacetazone and INAH also yielded good results with much less expenses to be incurred by the patients. Whether therapy with this 3 tier combination could be continued for a longer period with sustained improvement is yet to be assessed by further studies for a considerable period.

Adolescent↗
PubMed1979

Nature and familial character of lepromin sensitivity in 27 families and their siblings.

A group of 27 families consisting of 176 individuals had been investigated for the lepromin sensitivity (with Dharmendra antigen). The families were arranged under group A (9 families) in whom either of the parents or both were suffering from Lepromatous type of leprosy, group B numbering 4 families, of whom either of the parents or both were suffering from non-lepromatous type of leprosy and group C comprising 14 families where none of the parents was suffering from leprosy but some of the each family had the disease in their siblings. The present study points towards the possible genetic influence on lepromin sensitivity but at times may be influenced by the environmental factors. However the study does not permit to reach any valid conclusions; further elaborate investigations alone could prove the useful role of genetic influence in the propagation of lepromin sensitivity to the subsequent sibs.

Adolescent↗