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Biomedical subjects

H Singh

Publications and source records attributed to H Singh.

At least 451 records · Page 25Linked to original sources
PubMed1984

Vasectomy.

Explore the source record for details and available documents.

Humans↗
PubMed1983

Effect of gamma radiation on E. coli ribosomes, tRNA and aminoacyl-tRNA synthetases.

Gamma-irradiated E coli ribosomes and tRNA, in aerated solutions, were inactivated with D37 doses of 144 and 77 Gy, respectively. Aminoacyl-tRNA-synthetases were only slightly inactivated under comparable conditions. Effects of additives to ribosome and tRNA solutions suggest that hydroxyl radicals were the major damaging species, that superoxide anions were not damaging and that radiolytically-formed hydrogen peroxide was also unimportant. Part of the damage by hydroxyl radicals is expressed through secondary radicals produced from additives and buffers. Results obtained with three different buffers suggest that (1) acetate ions provide protection by competing for hydroxyl radicals, (2) chloride ions are without effect and (3) inactivation of ribosomes and aminoacyl-tRNA-synthetases in Tris-HCl/MgCl2 and phosphate/MgCl2 buffered solutions was similar but the tRNA inactivation was lower in Tris-HCl/MgCl2 buffer.

Amino Acyl-tRNA Synthetases↗
PubMed1983

Effect of gamma radiation on E. coli ribosomes. I. Inactivation by hydrogen atoms, hydroxyl radicals, hydrated electrons and secondary radicals.

E. coli ribosomes in aerated solutions were inactivated with a D37 dose of 144 Gy. In comparison, deaerated solutions bubbled with N2 or N2O showed a slight enhancement of the inactivation with D37 doses of 115 and 125 Gy, respectively. Isopropanol and tertiary-butanol provided partial protection. Results show that hydroxyl radicals, hydrated electrons and hydrogen atoms are involved in the inactivation process. Secondary radicals derived from the alcohols also inactivate ribosomes, with reduced efficiency.

1-Propanol↗
PubMed1983

Effect of gamma radiation on E. coli ribosomes, II. Efficiencies of inactivation by free radicals.

Efficiencies for the inactivation of ribosomes by the hydrogen atom, the hydrated electron, the hydroxyl radical and radicals derived from isopropanol and tertiary-butanol, have been calculated. The relative inactivation efficiencies of the hydrogen atom, the hydrated electron and the hydroxyl radical are 4.2, 0.8 and 1, respectively. The oxygen enhancement ratio for damage by the hydroxyl radical is 2.5.

1-Propanol↗
PubMed1983

beta-Adrenoceptor hypersensitivity after stopping oxprenolol: discrepant findings not attributable to methodology.

Using isoprenaline and glyceryl trinitrate (GTN) induced tachycardia we have compared the rebound beta-adrenoceptor hypersensitivity on stopping slow-release and conventional oxprenolol in young normotensive subjects. Heart rate on standing with GTN rose after stopping slow-release and conventional oxprenolol to peak levels on day 2 or 3 significantly greater than corresponding control levels off treatment on day 5. The isoprenaline CD25 (the dose required to increase heart rate by 25 beats/min) fell after stopping conventional oxprenolol to a significantly lower level on day 3 than the control level off treatment on day 5. Contrary to a recent report describing no rebound beta-adrenoceptor hypersensitivity on stopping slow-release oxprenolol we have demonstrated it after stopping slow release as well as conventional oxprenolol.

Adult↗
PubMed1983

Vasoplasty: flap operation.

Vasoplasty was performed in 40 cases by the flap technique; the patency rate was 79% and the pregnancy rate 34%. The method produced acceptable results almost as good as those achieved by microsurgery but without the need for expensive apparatus and long training.

Adult↗
PubMed1983

Morphologic and morphometric studies of muscle in idiopathic scoliosis.

The gluteus maximus and paraspinal muscles in 15 cases of idiopathic scoliosis at the apex of the curve showed myopathic changes and a significant decrease in the type II fibers. Fiber type II atrophy was observed only on the concave side. Ultrastructure of paraspinal and gluteus muscle biopsies showed disruption of myofilaments, Z band streaming and subsarcolemmal accumulation of glycogen, lipid and mitochondria. Quantitative estimation of these subcellular organelles pointed out that a higher glycogen content was significant in both paraspinal as well as the gluteus muscles while a higher mitochondrial content was significant only on the convex side and the gluteus muscle but not the concave side of the apex when compared to normal quadriceps muscle. These findings suggest that idiopathic scoliosis is a diffuse disease process and may be considered a primary muscle disease.

Adolescent↗
PubMed1983

Properties of dipeptidyl peptidase I from rabbit (Oryctolagus cuniculus) lungs.

Dipeptidyl peptidase 1 (DAP I; EC 3.4.14.1) was isolated from rabbit lungs and purified to apparent homogeneity. Similarly as the liver and spleen enzymes, it requires Cl- ions for its activity and is activated by thiol compounds. With Gly-Arg-2-naphthylamide as a substrate the broad pH optimum for DAP I activity ranged from 5.0 to 6.5; at pH 6.0-9.0 the enzyme catalysed the transamidation reaction. The Arrhenius plot for the DAP I activity at pH 5.0 was inflected at a point corresponding to 28 C. The enzyme was inhibited by the protease inhibitors, N alpha-tosyl-L-lysylchloromethane, N-tosyl-L-phenylalanylchloromethane, phenylmethylsulphonyl fluoride and antipain. Molecular weight of DAP I determined by sedimentation equilibrium in the presence of substrate was 128 000; in the absence of substrate two molecular forms of Mr of 135 000 and 91 600 were revealed. The Mr value determined on Sephadex G-200 was 154 000 +/- 7000. Molecular weight of the subunits determined by the two methods was about 21 000. Association of subunits over the pH range 4.6-6.0 was favoured by lowered temperature (7 C), presence of the substrate and increased enzyme concentration in the presence of the substrate. Only the forms of higher molecular weight, probably hexamers and octamers, exhibited enzymatic activity.

Animals↗