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R Chowdhury

Publications and source records attributed to R Chowdhury.

34 records · Page 2Linked to original sources
PubMed1998

Prolyl hydroxylase and tissue inhibitor of metalloproteinase in pure pancreatic juice in patients with chronic pancreatitis.

Prolyl hydroxylase is a key enzyme in collagen synthesis, and tissue inhibitor of metalloproteinase (TIMP) is known to suppress collagenolytic enzymes. To see whether the levels of these two enzymes in serum and human pure pancreatic juice (PPJ) are good indicators of pancreatic fibrosis in chronic pancreatitis (CP), we examined 15 controls, 14 alcoholics without evident pancreatic diseases (7 current drinkers and 7 former drinkers), and 19 patients with CP. Levels of the two enzymes were determined by a sandwich enzyme immunoassay method. TIMP-1 levels in PPJ were significantly higher in patients with CP than in controls and alcoholics, with overlap in only a few exceptional patients. A significant inverse correlation between TIMP-1 and bicarbonate output in PPJ was observed. Prolyl hydroxylase levels in PPJ, in contrast, were significantly higher in current drinkers than in patients with CP, controls, and former drinkers, with overlap in only a few exceptional patients with relapsing CP. Identical results were obtained even when the enzyme levels were expressed as nanograms per milligram of protein. Serum levels of prolyl hydroxylase and TIMP-1 showed no significant differences among controls, current alcoholics, former alcoholics, and patients with CP. These results indicate that the raised level of TIMP-1 in PPJ, unlike that of prolyl hydroxylase, is a good indicator of pancreatic fibrosis in CP.

Adult↗
PubMed1998

Risk of job-related injury among construction laborers with a diagnosis of substance abuse.

This study attempts to determine whether a diagnosis of substance abuse among construction laborers is associated with an increased risk of work-related injuries. Records for construction laborers in Washington State who were covered by health insurance through the local union were matched against workers' compensation records in the Washington State Department of Labor and Industries. Using the health insurance records, we identified those who had a diagnosis of substance abuse during the two-year period 1990-1991. Using the workers' compensation records, we were then able to compare injury rates for those with substance abuse diagnoses with the rates for those without such diagnoses. The total cohort consisted of 7,895 laborers. Among the 422 who had a substance abuse diagnosis, the rate of time-loss injuries per 100 full-time equivalent workers was 15.1, compared with 10.9 among the remainder of the cohort. Most of the difference appeared in the 25-34-year age group, in which the rate of injury per 100 full-time equivalent workers was 23.6 for substance abusers, compared with a rate of 12.2 for non-substance abusers, for a statistically significant relative risk of 1.93. The study suggests that younger workers might be an appropriate target for interventions aimed at reducing the level of substance abuse as a way of preventing injuries on the job. Studies by others have indicated some degree of success in this direction through the use of employee assistance programs in which the worker is referred to specific programs or providers for treatment. The state legislature in Washington has recently passed legislation providing incentives for the use of employee assistance programs. More effort is needed, however, to evaluate the effectiveness of such programs.

Accident Proneness↗
PubMed1997

The rpoH gene encoding sigma 32 homolog of Vibrio cholerae.

The Vibrio cholerae rpoH gene coding for the heat-shock sigma factor, sigma 32, has been cloned and shown to functionally complement Escherichia coli rpoH mutants. The nt sequence of the gene has been determined and the deduced aa sequence is more than 80% homologous to the E. coli rpoH gene product. Downstream of the V. cholerae rpoH gene, an unidentified dehydrogenase gene (udhA) is present on the opposite strand facing rpoH. The predicted secondary structure of the 5'-proximal region of V. cholerae rpoH mRNA is apparently different from the conserved secondary structures of the rpoH mRNA reported for several bacterial species. The 'RpoH box', a stretch of 9 aa (QRKLFFNLR) unique to sigma 32 factors, and the 'downstream box' sequence complementary to a part of the 16S rRNA, have been detected.

Amino Acid Sequence↗
PubMed1997

Bile affects production of virulence factors and motility of Vibrio cholerae.

The effect of bile on the expression of cholera toxin (CT) and the major subunit of the toxin-coregulated pilus (TcpA) and on motility was examined in the Vibrio cholerae O1 classical-biotype strains 0395 and 569B. Although the motility of the cells increased significantly in the presence of bile, transcription of the ctxAB genes, encoding CT, and of the tcpA gene was drastically reduced. In toxR mutant strains, motility is higher than in the wild-type strain and was further increased, by about 150%, in the presence of bile. Bile represses CT production in strain 569B-55, a toxR mutant of strain 569B, which normally produces more than 80% of the amount of CT synthesized in the wild-type cells. These results suggest that bile may target some factor other than ToxR that is involved in the regulation of CT production and motility. Bile has no effect on the relative amounts of the two outer membrane porins, OmpU and OmpT, which are under ToxR control.

Animals↗
PubMed1997

Fully committed.

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Acquired Immunodeficiency Syndrome↗
PubMed1996

Investigations into the mechanism of action of a novel nitric oxide generator on cellular respiration.

Nitric oxide may regulate cellular respiration by competition with oxygen at mitochondrial cytochrome oxidase. Using an astrocyte-derived cell line, we have compared the mechanism of action of the nitric oxide-generating compound Roussin's black salt with that of sodium nitroprusside on cellular oxygen consumption. Intense light exposure induced the release of large quantities of nitric oxide from both of the donor compounds. However, in room light only Roussin's black salt generated low levels of the radical. Simultaneous measurement of oxygen consumption and of nitric oxide production demonstrated that sodium nitroprusside only had inhibitory actions when exposed to intense light (nitric oxide release), whereas Roussin's black salt had inhibitory actions in room light. Extracellular haemoglobin did not prevent the inhibition of respiration rate induced by Roussin's black salt even though stimulation of nitric oxide release on light exposure was markedly reduced. Preincubation of cells with Roussin's black salt and subsequent measurement of levels of light-liberated nitric oxide demonstrated that the compound was rapidly internalised. The uptake of sodium nitroprusside was minimal. These data suggest that, in contrast to sodium nitroprusside, the cellular internalisation of Roussin's black salt allows site-directed nitric oxide release and very effective inhibition of cellular respiration.

Animals↗
PubMed1994

Heat shock response and heat shock protein antigens of Vibrio cholerae.

Sixteen heat shock proteins (Hsps) have been identified in the hypertoxinogenic strain 569B of Vibrio cholerae which are synthesized in response to small and large elevations of temperature. The induction of the Hsps is necessary for the cells to survive the deleterious effects of heat. There is no difference in the pattern of induction of the Hsps in V. cholerae strains varying in levels of toxinogenicity. One of the major low-molecular-mass Hsps, a 16-kDa protein, is preferentially degraded following shift down of temperature. This protein is induced at a much lower level at high temperatures in cells maintained in the laboratory for a prolonged period. The only Hsp located in the outer membrane of V. cholerae cells is a 23-kDa protein. Western immunoblot analysis with human immune sera collected from convalescent cholera patients revealed that this protein is markedly immunogenic. The human immune serum also reacted with the 69- and 16-kDa major Hsps and the 88-, 66-, and 46-kDa Hsps but not with the 61-kDa major Hsp identified as the groEL gene product. All major Hsps reacted with rabbit anti-V. cholerae sera. Ethanol stress leads to the induction of four of the major Hsps and three additional proteins.

Adaptation, Biological↗
PubMed1993

Prevalence of dental caries in handicapped children of Calcutta.

A total of 1042, 3-14-year-old children with different types of handicapping conditions when recorded for dental caries using WHO 1987 caries recording index revealed that dental caries experience was higher in handicapped children than normal children. The prevalence of dental caries was highest in mentally retarded children followed by cerebral palsied, blind, epileptic, physically handicapped, children with Down's syndrome and deaf and dumb. Higher deft+DMFT was recorded in mandibular teeth compared to maxillary teeth.

Adolescent↗
PubMed1992

A 14-kilodalton inner membrane protein of Vibrio cholerae biotype e1 tor confers resistance to group IV choleraphage infection to classical vibrios.

Choleraphage phi 149 differentiates the two biotypes, classical and el tor, of Vibrio cholerae. This phage cannot replicate in V. cholerae biotype el tor cells because the concatemeric DNA intermediates produced are unstable and cannot be chased to mature phage DNA. A V. cholerae biotype el tor gene coding for a 14,000-Da inner membrane protein which destabilizes the concatemeric DNA intermediates by hindering their binding to the cell membrane has been identified. Presumably, a 22,000-Da V. cholerae biotype el tor protein might also have a role in conferring phage phi 149 resistance to cells belonging to the biotype el tor. A nucleotide sequence homologous to the 1.2-kb V. cholerae biotype el tor DNA coding for both the 14,000- and 22,000-Da proteins is present in all strains of classical vibrios but is not transcribed. The nucleotide sequence of the gene coding for the 14,000-Da protein has been determined.

Amino Acid Sequence↗
PubMed1989

Abortive replication of choleraphage phi 149 in Vibrio cholerae biotype el tor.

Choleraphage phi 149 adsorbed irreversibly to Vibrio cholerae biotype el tor cells, and 50% of the injected phage DNA bound to the cell membrane. Although no infectious centers were produced at any time during infection, the host macromolecular syntheses were shut off and the host DNA underwent chloramphenicol-inhibitable degradation. Synthesis of monomeric phage DNA continued similar to that observed in the permissive host. However, the concatemeric DNA intermediates produced were unstable and could not be chased to mature phage DNA. Pulse-labeling of UV-irradiated infected cells at different times during infection allowed identification of phage-specific proteins made in this nonpermissive host. Although most of the early proteins were made, only some of the late proteins were transiently synthesized.

Bacteriophages↗
PubMed1988

Intracellular development of choleraphage phi 149 under permissive and nonpermissive conditions: an electron microscopic study.

Intracellular development of choleraphage phi 149 following infection of Vibrio cholerae and Vibrio eltor cells under different conditions was examined by thin-section electron microscopy. Degradation of the host DNA following infection and formation of mature phage particles inside the infected cells were demonstrated. The concatemeric DNA intermediate formed during intracellular replication of phi 149 DNA in permissive hosts was resolved. In confirmation of biochemical evidence, no concatemeric DNA intermediate was observed for infection in high-phosphate medium.

Bacteriophages↗
PubMed1987

Replication and packaging of choleraphage phi 149 DNA.

The intercellular replication of the circularly permuted DNA of choleraphage phi 149 involves a concatemeric DNA structure with a size equivalent to six genome lengths. The synthesis of both monomeric and concatemeric DNAs during replication of phi 149 occurred in the cytoplasm. The concatemers served as the substrate for the synthesis of mature phage DNA, which was eventually packaged by a headful mechanism starting from a unique pac site in the concatemeric DNA. Packaging of DNA into phage heads involved binding of concatemeric DNA to the cell membrane. A scheme involving sequential packaging of five headfuls proceeding in the counterclockwise direction from the pac site is proposed. After infection under high-phosphate conditions, the concatemeric DNA intermediates were not formed, although synthesis of monomeric molecules was unaffected.

Bacterial Proteins↗
PubMed1986

Infection by choleraphage phi 138: bacteriophage DNA and replicative intermediates.

Choleraphage phi 138 contains a linear, double-stranded, circularly permuted DNA molecule of 30 X 10(6) daltons or 45 kilobase pairs. Upon infection, the host DNA is degraded, and synthesis of phage-specific DNA is detectable 20 min after infection. The phage utilizes primarily the host DNA degradation products for its own DNA synthesis. A physical map of phi 138 DNA was constructed with the restriction endonucleases Bg/II, HindIII, and PstI. A concatemeric replicative DNA intermediate equivalent to eight mature genome lengths was identified. The concatemer was shown to be the precursor for the synthesis of mature bacteriophage DNA which is subsequently packaged by a headful mechanism.

Bacteriophages↗
PubMedDate not supplied

Folk terminology for diarrhea in rural Bangladesh.

Diarrhea, a descriptive term used in medical science for a variety of clinical diseases, denotes an illness that is categorized differently and known by numerous terms in various cultures. These diversified classifications and terminologies are based on the symptoms of diarrheal disorders, their perceived etiology, and their treatment. In Bangladesh, four types of illnesses with names derived from folk terminology have been identified for which the clinical symptoms resemble those of diarrhea. These include dud haga, which is due to ingestion of breast milk by infants; ajirno, which is due to overeating; amasha, a mucoid diarrhea; and daeria, which is severe watery diarrhea or cholera. Use of the word diarrhea in epidemiologic evaluations was discovered to be problematic; people confused this term with daeria, which accounted for only 5% of all episodes of diarrhea. The implications of such epidemiologic information for a large-scale program of oral rehydration therapy are also discussed.

Bangladesh↗