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Biomedical subjects

A Chaudhuri

Publications and source records attributed to A Chaudhuri.

At least 163 records · Page 9Linked to original sources
PubMed1990

Effect of testosterone on adrenal corticosteroidogenesis in lithium treated male rats.

Lithium chloride at a dose of 200 micrograms/100 g body weight/day given for 21 days caused a significant increase in adrenal weight, adrenal 5-ene-3 beta-hydroxysteroid dehydrogenase (5-ene-3 beta-HSD) activity along with elevation in serum level of corticosterone on the 22nd day in the rat. Administration of testosterone for the last 14 days to lithium treated rats caused a significant decrease in adrenal weight, adrenal 5-ene-3 beta-HSD activity and serum level of corticosterone in comparison to lithium treated animals.

3-Hydroxysteroid Dehydrogenases↗
PubMed1990

Acid and alkaline phosphatase activities in lithium treated testis, prostate and seminal vesicles of adult albino rats: evidence of duration and dose dependent response.

Changes in the activities of acid and alkaline phosphatase were observed in the testis, prostate and seminal vesicle after the injection of lithium chloride at the doses of 100, 200 and 400 micrograms/100 g body weight/day for 7, 14 and 21 days. The studies indicate that 200 and 400 micrograms/100 g body weight for 14 days and 21 days showed a significant inhibition in the activity of acid phosphatase in all the above reproductive organs. There is a significant stimulation of alkaline phosphatase activity at the doses of 200 and 400 micrograms of lithium after 21 days of treatment in testis, prostate and seminal vesicle along with significant decrease in accessory sex organs weight in comparison to control animal. Therefore, it is evident that the effect of lithium on male reproductive organs mainly depends on the amount of the drug being injected and the duration of treatment to it.

Acid Phosphatase↗
PubMed1990

Effect of lithium chloride on spermatogenesis and testicular delta 5-3 beta, 17 beta-hydroxysteroid dehydrogenase activities in the 'antiserum to luteinizing hormone' treated toad (Bufo melanostictus).

Activities of delta 5-3 beta- and 17 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD and 17 beta-HSD), Leydig cell nuclear area (LCNA) and spermatogenesis in the testis were observed after injection of lithium chloride in the 'antiserum to luteinizing hormone (LH)' treated toad. A significant decrease in the activities of steroidogenic enzymes, LCNA and spermatogenesis were noticed after the injections of 'antiserum to LH' to toads. Further decrease in the activities of the above parameters was observed in the lithium chloride--'antiserum to LH' treated toad. It is suggested that lithium chloride may inhibits testicular function without modulating the pituitary activity.

17-Hydroxysteroid Dehydrogenases↗
PubMed1989

Purification and characterization of an erythrocyte membrane protein complex carrying Duffy blood group antigenicity. Possible receptor for Plasmodium vivax and Plasmodium knowlesi malaria parasite.

A murine monoclonal antibody, named anti-Fy6, which agglutinates all human red cells except those of Fy(a-b) phenotype was used for purification and characterization of Duffy antigens. Duffy antigens are multimeric red cell membrane proteins composed of different subunits of which only one, designated pD protein, reacts in immunoblots with the murine monoclonal antibody anti-Fy6. Affinity-purified detergent-soluble antigen-antibody complex obtained from red cells, surface-labeled with 125I yielded a complex pattern of bands when separated by polyacrylamide gel electrophoresis. Proteins that react with anti-Fy6 in immunoblots are: pA and pB (greater than 100 kDa) and pD (36-46 kDa). Electroeluted pD protein aggregates and generates bands of similar molecular mass to pA and pB proteins. Electroeluted pA and pB proteins disaggregate yielding pD protein. Oligomers and monomers of pD protein are present in red cells carrying Duffy antigens and absent in Fy(a-b-) cells. Six other proteins of molecular weight ranging from 68 to 21 kDa either associate or co-purify with pD protein. These proteins are only present in Duffy antigen positive cells. The pD protein is different in Fy(a+b-) and Fy(a-b+) cells by fingerprint analysis. Human antisera identify the same proteins in red cell carrying Duffy antigens as the murine monoclonal antibody anti-Fy6.

Animals↗
PubMed1988

Isolation of a gene required for growth of Escherichia coli on fumarate and H2.

Two mutant strains of Escherichia coli, AK11 and AK22, express normal levels of hydrogenase activity, assayed by deuterium exchange, when grown on glucose or complex medium but cannot reduce methyl viologen by H2 nor grow on fumarate plus H2. The mutant strains also lack formate hydrogenlyase and formate dehydrogenase activities. The mutation in these strains was located near minute 17 of the genome map and a single mutation was shown to be responsible for loss of both hydrogen uptake and formate-related activities. Membrane vesicles and solubilized membranes of strains AK11 and AK22 were capable of methyl viologen reduction by H2 and had the normal complement of hydrogenase isoenzymes 1 and 2. Intact cells of the mutant strains could reduce fumarate by H2 but could not grow under these conditions. A plasmid, pAK11, was isolated, as well as smaller plasmids derived from it, which restored the hydrogen uptake activities in the two mutant strains, the smallest active DNA fragment being 1.4 kb. The formate activities were partially restored by some of the plasmids. The plasmids which restored hydrogen uptake activities led to synthesis of a polypeptide of subunit molecular mass 30 kDa.

Bacterial Proteins↗
PubMed1988

Sarcoidosis.

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Humans↗
PubMed1988

Hypoglycaemia.

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Humans↗
PubMed1988

Localization of the McLeod locus (XK) within Xp21 by deletion analysis.

The McLeod phenotype is an X-linked, recessive disorder in which the red blood cells demonstrate acanthocytic morphology and weakened antigenicity in the Kell blood group system. The phenotype is associated with a reduction of in vivo red cell survival, but the permanent hemolytic state is usually compensated by erythropoietic hyperplasia. The McLeod phenotype is accompanied by either a subclinical myopathy and elevated creatine kinase (CK) or X-linked chronic granulomatous disease (CGD). Seven males with the McLeod red-blood-cell phenotype and associated myopathy but not CGD, one male with the McLeod phenotype associated with CGD, and two males known to possess large deletions of the Duchenne muscular dystrophy (DMD) locus were studied. DNA isolated from each patient was screened for the presence or absence of various cloned sequences located in the Xp21 region of the human X chromosome. Two of the seven males who have only the McLeod phenotype and are cousins exhibit deletions for four Xp21 cloned fragments but are not deleted for any portion of either the CGD or the DMD loci. Comparison of the cloned segments absent from these two McLeod cousins with those absent from the two DMD boys and the CGD/McLeod patient leads to the submapping of various cloned DNA segments within the Xp21 region. The results place the locus for the McLeod phenotype within a 500-kb interval distal from the CGD locus toward the DMD locus.

Adult↗
PubMed1987

Isolation of genes required for hydrogenase synthesis in Escherichia coli.

A mutant strain of Escherichia coli, strain AK23, is devoid of hydrogenase activity when grown anaerobically on glucose and cannot grow on H2 plus fumarate. From E. coli chromosomal DNA library, a plasmid, pAK23, was isolated which restored hydrogenase activity in this strain. Two smaller plasmids, pAK23C and pAK23S, containing different parts of the insert DNA fragment of plasmid pAK23, were isolated. The former plasmid restored activity in strain AK23 while the latter did not. The smallest active DNA fragment in plasmid pAK23C was 0.9 kb. This gene is designated hydE. Plasmids pAK23 and pAK23S restored activity in another hydrogenase-negative strain, SE-3-1 (hydB), while plasmid pAK23C did not, suggesting that plasmid pAK23 contains two genes required for hydrogenase expression. Strain AK23 was also devoid of formate hydrogenlyase and formate dehydrogenase activities and these activities were restored by some of the plasmids. Hydrogenase and formate-related activities in strain AK23 were restored by growth of cells in a high concentration of nickel. Plasmid pAK23C led to synthesis of a polypeptide of subunit molecular mass 36 kDa and plasmid pAK23S led to synthesis of polypeptides of subunit molecular masses 30 and 41 kDa.

Cloning, Molecular↗
PubMed1987

Renal failure.

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Acute Kidney Injury↗
PubMed1986

Transcriptional induction by interferon. New protein(s) determine the extent and length of the induction.

Interferon (IFN) treatment of human fibroblasts induces the transcription of two genes, IFN-IND-1 and -2, to a maximal level between 30 min and 2 h. Continued exposure to IFN results in a "desensitization" characterized by a return to pretreatment levels of transcription and the inability of further IFN treatment to reinduce the transcription of these genes. The imposition and the maintenance of desensitization apparently requires continuous protein synthesis because both can be reversed by cycloheximide. Thus a regulatory circuit of transcription for IFN-IND-1 and -2 includes a prompt IFN-induced transcriptional increase followed shortly by a negative regulatory response requiring a labile protein(s) that limits the duration of the increased transcriptional response.

Autoradiography↗
PubMed1986

Interferon-stimulated transcription: isolation of an inducible gene and identification of its regulatory region.

A human gene (termed ISG-54K) that is induced from near undetectable levels to high transcriptional activity by alpha- and beta-interferons has been cloned. The genomic structure and nucleotide sequence of the coding region were determined and the RNA initiation site was identified. The 5' portion of the gene was fused with a heterologous gene lacking an active promoter in recombinant plasmid and adenoviral vectors. These fusion genes were used to assess the activity of the ISG-54K promoter in response to interferon. RNA was formed in HeLa cells from recombinant plasmids only in response to interferon. Furthermore, in human diploid fibroblasts, infection with the recombinant adenovirus vector resulted in a 50-fold increase in specific RNA in response to interferon, followed by a subsequent decrease, imitating the natural regulated transcriptional cycle of the endogenous gene.

Amino Acid Sequence↗
PubMed1985

Eukaryotic initiation factor 5 from calf liver is a single polypeptide chain protein of Mr = 62,000.

Eukaryotic initiation factor 5 (eIF-5), which specifically catalyzes the joining of a 60 S ribosomal subunit to a 40 S initiation complex to form a functional 80 S initiation complex, has been purified from ribosomal salt wash proteins of calf liver. The purified factor exhibits only one polypeptide band of Mr = 62,000 following electrophoresis in 10% polyacrylamide gels in the presence of sodium dodecyl sulfate. The native protein has a sedimentation coefficient of 4.2 S and a Stokes radius of 33 A which is consistent with eIF-5 being a monomeric protein of Mr = 58,000-62,000. Less pure preparations of eIF-5 elute in gel filtration columns with an apparent Mr of 160,000-180,000 presumably due to association of eIF-5 with other high molecular weight proteins since eIF-5 activity present in such preparations can also be shown by gel electrophoretic separation under denaturing conditions to be associated with a 62,000-dalton protein. Furthermore, eIF-5 purified from calf liver extracts with or without a number of protease inhibitors is indistinguishable with regard to molecular weight and final specific activity of purified preparations. The purified factor catalyzes the hydrolysis of GTP present in 40 S initiation complexes in the absence of 60 S ribosomal subunits. The presence of 60 S ribosomal subunits neither stimulates nor inhibits the hydrolysis of GTP. However, the factor cannot mediate 40 S or 40 + 60 S ribosome-dependent hydrolysis of GTP in the absence of Met-tRNAf or other components required for 40 S initiation complex formation. It can be calculated that 1 pmol of eIF-5 protein can catalyze the formation of at least 10 pmol of 80 S initiation complex under the conditions of in vitro initiation reactions.

Animals↗
PubMed1985

Formation and release of eukaryotic initiation factor 2 X GDP complex during eukaryotic ribosomal polypeptide chain initiation complex formation.

The formation and release of an eukaryotic initiation factor (eIF)-2 X GDP binary complex during eIF-5-mediated assembly of an 80 S ribosomal polypeptide chain initiation complex have been studied by sucrose gradient centrifugation analysis. Isolated 40 S initiation complex reacts with eIF-5 and 60 S ribosomal subunits to form an 80 S ribosomal initiation complex with concomitant hydrolysis of an equimolar amount of bound GTP to GDP and Pi. Sucrose gradient analysis of reaction products revealed that GDP was released from ribosomes as an eIF-2 X GDP complex. Evidence is presented that eIF-5-mediated hydrolysis releases the GTP bound to the 40 S initiation complex as an intact eIF-2 X GDP complex rather than as free GDP and eIF-2 which subsequently recombine to form the binary complex. Furthermore, formation and release of eIF-2 X GDP from the ribosomal complex do not require concomitant formation of an 80 S initiation complex since both reactions occur efficiently when the 40 S initiation complex reacts with eIF-5 in the absence of 60 S ribosomal subunits. These results, along with the observation that the 40 S initiation complex formed with the nonhydrolyzable analogue of GTP, 5'-guanylylmethylene diphosphonate, can neither join a 60 S ribosomal subunit nor releases ribosome-bound eIF-2, suggest that following eIF-5-mediated hydrolysis of GTP bound to the 40 S initiation complex, both Pi and eIF-2 X GDP complex are released from ribosomes prior to the joining of 60 S ribosomal subunits to the 40 S initiation complex.

Animals↗