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Biomedical subjects

S C Dhar

Publications and source records attributed to S C Dhar.

50 records · Page 3Linked to original sources
PubMed1987

Alterations in lung and skin compositions of rat in bleomycin-induced fibrosis.

Male albino rats were given bleomycin subcutaneously (5 mg potency/kg body weight twice a week) for a period of 6 weeks. At this dosage, mortality was found to be nil with marked fibrotic changes. Pulmonary and cutaneous changes at the end of 2, 4, and 6 weeks of treatment were investigated both by light microscopy and analyses of the intra- and extracellular components. Histologically, fibrosis set in as early as 2 weeks of treatment with bleomycin and was pronounced with increasing duration of treatment. Biochemically, total collagen and hexosamine contents of lung and skin increased significantly compared to control toward the end of treatment period. Thus, this animal model can be conveniently used to mimic the human condition and to test effective antifibrotic agents.

Animals↗
PubMed1985

Purification of subtilisin by single-step affinity chromatography.

The dye 4-(4-aminophenylazo)phenylarsonic acid was coupled to activated CH-Sepharose 4B and the resulting affinity matrix was shown to be highly efficient for the purification of subtilisin. A crystalline subtilisin was purified to homogeneity using this affinity chromatography procedure with a purification fold of 1.4 and with an enzyme activity yield of 98%. Similarly subtilisin from a crude enzyme preparation was purified to 211 fold by this single step procedure with 94% recovery of the enzyme activity. The purified enzymes were shown to be homogeneous by polyacrylamide gel electrophoresis.

Arsenicals↗
PubMed1980

Trypsinogen-kinase from Aspergillus fumigatus.

The activation of bovine trypsinogen by an extracellular acid proteinase from A. fumigatus is described. The enzyme activates trypsinogen optimally at pH 3.5 and 32 degrees C. The effect of substrate and enzyme concentrations on the activation has been studied and the Km-value has been determined.

Animals↗
PubMedDate not supplied

Gallstone disease in a rural Bangladeshi community.

BACKGROUND: The prevalence of gallstone disease (GSD) in Bangladesh is not known. We evaluated the prevalence of GSD and its relation with certain factors in a rural community in Bangladesh. METHODS: A total of 1332 persons aged 15 years and above from two villages were invited to participate in the study; 1,058 (80%) subjects responded after three invitations. Each subject answered a questionnaire, including demographic features, and underwent an upper abdominal ultrasound examination. RESULTS: GSD (current cholelithiasis and history of cholecystectomy) was detected in 5.4% of subjects. The prevalence was higher in women (7.7%) than in men (3.3%; p=0.002) The prevalence rates increased from 0.9% to 10% (p=0.0124) from those aged <30 years to those >50 years. A larger proportion of obese subjects (25/52; 48.1%) had GSD than non-obese subjects (32/1006; 3.2%). Prevalence in low, middle and high socio-economic classes was 1.5%, 5.7% and 13.4%, respectively (p=0.000). A majority (71.9%) of subjects with GSD were asymptomatic. CONCLUSION: Approximately 5% of the Bangladeshi rural community evaluated have GSD. Higher age, female gender, presence of obesity and higher socio-economic class were associated with higher prevalence of GSD.

Adolescent↗
PubMedDate not supplied

Studies on the physico-chemical properties of alhagain.

The protease isolated jawasee shrub was found to hydrolyze egg albumin, casein, haemoglobin and gelatin optimally near neutral pH. Fibrin, bovin serum albumin, skin albumin and skin mucoids were hydrolyzed at slightly alkaline pH, while skin globulins were hydrolyzed at slightly acidic pH. The enzyme had no effect of fibrous collagen. The optimum conditions for the hydrolysis of 50 mg of egg albumin were found to be 50 mg of alhagain at pH 6.0 and 45 degrees C for 30 minutes. A Km value of 4.4 X 10(-3) M was obtained from the Lineweaver-Burk plot for the hydrolysis of egg albumin. The enzyme was found to be comparatively thermostable and was most stable at pH 4.7. Ultraviolet irradiation exhibited no appreciable effect on the enzyme activity. The ultraviolet absorption spectrum of alhagain in bi-distilled water resembles those of bromelain and trypsin. The sugar-containing enzyme was found to have a molecular weight of 20,650. The enzymeconsists of 189 amino acid residues per molecule, neutral and acidic amino acids being present in high concentrations. The partial specific volume of alhagain was calculated to be 0.743 ml/g from its amino acid composition. Phenylalnine and arginine formed the amino terminal amino acids of alhagain, while aspartic acid and serine were identified as its carboxy terminal amino acids. Results are discussed with relation to other plant proteases.

Amino Acids↗
PubMedDate not supplied

Effect of a new non-steroidal anti-inflammatory agent on lysosomal stability in adjuvant induced arthritis.

The effect of new non-steroidal anti-inflammatory agents on lysosomal stability was studied by determining the activity of beta-glucuronidase, a typical lysosomal enzyme, in various sub-cellular fractions and its release from the lysosome-rich fraction. Adjuvant arthritic animals showed a significant increase in the beta-glucuronidase activity in sub-cellular fractions. The increased rate of the release of beta-glucuronidase from lysosome-rich fraction clearly suggested that arthritic syndrome caused decreased stability of the lysosomes. Administration of boswellic acids or salai-guggal to arthritic animals was found to increase the lysosomal stability by inhibiting the rate of release from lysosome-rich fraction and reducing beta-glucuronidase activity in various sub-cellular fractions. Of the two anti-inflammatory agents tested, salai-guggal was found to afford more therapeutic value than boswellic acids.

Animals↗
PubMedDate not supplied

Purification and properties of a glucoamylase fraction from the culture filtrate of Rhizopus nodosus.

A glucoamylase was isolated from the culture filtrate of Rhizopus nodosus and was separated from the acid lipase by DEAE-cellulose chromatography at pH 8.0 It was purified by Concanavalin A Sepharose 4B affinity chromatography followed by CM-Sephadex chromatography 387 fold with 30.7% yield. The homogeneity of the enzyme were confirmed by polyacrylamide gel electrophoresis and immunological studies. The different physico-chemical properties of the enzyme were studied. The molecular weight of the enzyme was found to be 71,000. Ethylenediaminetetraacetic acid had no effect on the enzyme whereas Hg2+ partially inhibited the enzyme activity. Tryptophan residues were found to be essential for the enzyme activity.

Chromatography, Affinity↗
PubMedDate not supplied

Further studies on the physico-chemical properties of Rhizopus nodosus acid lipase.

The Km value of R. nodosus acid lipase was found to be 5 X 10(-2) M and 8 X 10(-3) M with olive oil and tricaprylin respectively. The lipase hydrolyzed triglycerides better than synthetic detergents and methyl esters. When synthetic triglycerides varying in fatty acid chain length were used, maximum hydrolysis was observed with tricaprylin as the substrate. Positional specificity studies indicated a preference for primary esters. The lipase was activated by albumin, NaCl and taurocholate whereas heparin had no effect. The lipase contains a single polypeptide chain with 298 amino acid residues. Glutamic acid and isoleucine were found to be the amino and carboxy-terminal residues, respectively. By gel filtration and SDS-PAGE the molecular weight was determined to be 40,000 +/- 500. The lipase was susceptible to photooxidation in the presence of methylene blue and Rose bengal whereas PMSF and thiol-group specific reagents had no appreciable effect on the lipase activity. NBS inactivated the lipase. Tryptophan residues were found to be essential for the lipase activity.

Kinetics↗
PubMedDate not supplied

Physico-chemical properties of the acid proteinase from A. fumigatus.

The physico-chemical properties of the purified acid proteinase were investigated. This enzyme was found to hydrolyze hemoglobin maximally among the different substrates used. The maximum hydrolysis of hemoglobin was found at pH 2.8 and 45 degrees C in 30 min. Km value of 5.5 X 10(-4) M was obtained from the Lineweaver Burk plot for the hydrolysis of hemoglobin. The enzyme was found to be most stable at pH 4.9. The maximum stability of the enzyme was observed with 2 per cent casein as a stabilising agent. It was found to have a molecular weight 37,500 consisting of 298 aminoacid residues. The partial specific volume of the acid proteinase was found to be 0.734 ml/g. Leucine and alanine were the amino and carboxy terminal aminoacids of the acid proteinase respectively.

Amino Acids↗
PubMedDate not supplied

Studies on the peptide bond specificity and the essential groups of an acid proteinase from Aspergillus fumigatus.

The specificity and mode of action of an acid proteinase from A. fumigatus was studied with B-chain of insulin, angiotensin II and bradykinin. With reference to the known structure of the B-chain of insulin and angiotensin II, the major sites of action were determined. Acid proteinase of A. fumigatus hydrolyzed primarily three peptide bonds in the B-chain of insulin viz. i. His(5)-Leu(6); ii. Tyr(16)-Leu(17) and iii. Phe(24)-Phe(25) bonds. Additional cleavages of the bonds His(10)-Leu(11) and Leu(15-Tyr(16) were also noted. Primary splitting sites, Tyr(16)-Leu(17) and Phe(24)-Phe(25) were identical with those reported in the work of porcine pepsin C (EC 3.4.23.3). Hydrolysis of angiotensin II was observed at Tyr(4)-Ile(5) bond. The acid proteinase was found not to be inactivated by EDTA, DEP and PCMB. The pepsin specific inhibitors viz. DAN/Cu II and EPNP showed quite appreciable inhibition, while SDS completely inactivated this acid proteinase.

Amino Acids↗
PubMedDate not supplied

Refractory immune thrombocytopenia after heart transplantation: a case report.

Chronic immune thrombocytopenia responds to steroids and splenectomy in approximately 80% of the patients. Intravenous immunoglobulin, plasmapheresis, combination chemotherapy, and androgens may help in refractory cases. This report describes the course and management of refractory immune thrombocytopenia after heart transplantation.

Autoantibodies↗