Search PubMed⌕ Search

Biomedical subjects

H Singh

Publications and source records attributed to H Singh.

At least 325 records · Page 18Linked to original sources
PubMed1989

Dihydroxyacetone phosphate acyltransferase and alkyldihydroxyacetone phosphate synthase activities in rat liver subcellular fractions and human skin fibroblasts.

Dihydroxyacetone phosphate acyltransferase (DHAP-AT) and alkyldihydroxyacetone phosphate synthase (DHAP-synthase) activities were examined in subcellular fractions of rat liver. The results indicate that at least 80% of DHAP-AT (assays carried out at pH 5.4) activity in rat liver is in peroxisomes, and the remaining activity is mitochondrial. In contrast to DHAP-AT, DHAP-synthase was detected in all subcellular fractions analyzed but the activity in peroxisomes was 208-fold and 42-fold greater compared to mitochondria and microsomes, respectively. We estimate that at least 70% of the DHAP-synthase activity in rat liver is in peroxisomes. DHAP-AT and DHAP-synthase activities were also examined in homogenates of skin fibroblasts from patients with inherited defects in peroxisomal structure and/or function. Both the enzyme activities were deficient in Zellweger syndrome whereas the activities were only partially deficient in infantile Refsum's disease. Greater reduction in DHAP-synthase activity, but only a partial reduction in DHAP-AT activity was observed in rhizomelic chondrodysplasia punctata. However, both DHAP-AT and DHAP-synthase activities were either normal or near normal in Refsum's disease or X-linked adrenoleukodystrophy. The results reported suggest that various peroxisomal disease states can be identified based on DHAP-AT and DHAP-synthase activities in skin fibroblasts of patients.

Acyltransferases↗
PubMed1989

Nifedipine attenuates the intraocular pressure response to intubation following succinylcholine.

Forty patients without eye disease, undergoing elective nonophthalmic surgery, were studied to evaluate the efficacy of sublingual nifedipine in attenuating the intraocular pressure response to succinylcholine administration, laryngoscopy and intubation. The patients were randomly given either nifedipine 10 mg or placebo sublingually 20 minutes before induction of anaesthesia. Intraocular pressure (IOP) and systolic blood pressure (SBP) were recorded before and after induction of anaesthesia. The IOP response to succinylcholine administration, laryngoscopy and intubation was significantly less in patients receiving nifedipine (P less than 0.01). The mean maximum rise in IOP above basal level at one minute post-intubation was 7.82 mmHg in the control group compared with 0.15 mmHg in the nifedipine pre-treated group. These results suggest that sublingual nifedipine is effective in attenuating the IOP response after succinylcholine administration, laryngoscopy and intubation.

Adult↗
PubMed1989

Ovarian toxicity of benzo(a)pyrene and metabolites in mice.

The effect of intraovarian injection of benzo(a)pyrene (BP) or one of three metabolites: +7,8-oxide (7,8-O), (-)-dihydrodiol (DHD), and (+)-diol-epoxide-2 (DE2) on ovarian volume, weight, and follicle number was investigated in DBA/2N (D2), C57BL/6N (B6), and (DBA/2N x C57BL/6N)F1 (F1) mice. Female mice, 6 to 8 weeks old, were treated by injection into the right ovary with the indicated compound (10 micrograms in 1 microL DMSO). The left ovary was untreated. Two weeks following treatment both ovaries were removed, fixed in Bouin's medium, serially sectioned, and stained with hematoxylin and eosin. Right ovarian weight was decreased in D2 mice treated with BP (P less than 0.01 and DHD (P less than 0.01). Left ovarian weight was increased in D2 mice treated with DE2 (P less than 0.05). BP decreased right ovarian volume in D2 (P less than 0.01) and F1 (P less than 0.01) mice. 7,8-O decreased right ovarian volume in D2 mice (P less than 0.05). DHD decreased right ovarian volume in D2 (P less than 0.01) and F1 (P less than 0.05) mice. DE2 decreased right ovarian volume in D2 (P less than 0.01) and F1 (P less than 0.01) mice. Left ovarian volume was increased in B6 (P less than 0.01) and D2 (P less than 0.05) mice treated with DE2. The number of small follicles was decreased in D2, B6, and F1 mice treated with DE2 (P less than 0.01). BP and DHD also decreased small follicle number in D2 and F1 mice (P less than 0.01). The number of growing follicles was decreased in B6, D2, and F1 mice treated with DE2 (P less than 0.01). Treatment with DHD decreased the number of growing follicles in D2 mice (P less than 0.05). The number of antral follicles was reduced in F1 mice treated with BP (P less than 0.05), DHD (P less than 0.01), and DE2 (P less than 0.01). The number of antral follicles was also reduced in B6 mice treated with DE2 (P less than 0.01) and in D2 mice treated with DHD (P less than 0.05) and D2 mice treated with DE2 (P less than 0.01). These experiments suggest that toxic effects to one ovary may result in compensatory hypertrophy of the contralateral ovary. Morphometric analysis of the ovary, including ovarian volume, represents a useful objective measure of ovarian toxicity.

Animals↗
PubMed1989

Binding of zinc to bovine and human milk proteins.

Zn binding by whole bovine and human casein and by purified bovine caseins and whey proteins was investigated by equilibrium dialysis. Bovine alpha s1-casein had the greatest Zn-binding capacity (approximately 11 atoms Zn/mol). Protein aggregation was observed as Zn concentration was increased and the protein precipitated at a free Zn concentration of 1.7 mM. Zn binding increased with increasing pH in the range 5.4-7.0 and decreased with increasing ionic strength. Competition between Zn and Ca was observed for binding to alpha s1-casein indicating common binding sites for these two metals. Bovine beta-casein bound up to 8 atoms Zn/mol and precipitated at a free Zn concentration of approximately 2.5 mM, while kappa-casein bound 1-2 atoms Zn/mol. Whole bovine and human casein bound 5-8 atoms Zn/mol and precipitated at a free Zn concentration of approximately 2.0 mM. Scatchard plots for Zn binding to caseins showed upward convexity, possibly due to Zn-induced association of caseins. Apparent average association constants (Kapp) for all caseins were similar (log Kapp 3.0-3.2). Enzymic dephosphorylation of alpha s1- or whole bovine casein markedly reduced, but did not eliminate, Zn binding. Thus, phosphoserine residues appeared to be the primary Zn-binding sites in caseins. With the exception of bovine serum albumin, which bound over 8 atoms Zn/mol, the bovine whey proteins, beta-lactoglobulin, alpha-lactalbumin and lactotransferrin, had little capacity for Zn binding.

Animals↗
PubMed1989

Zinc binding in bovine milk.

About 90% of the Zn in bovine skim milk was sedimented by ultracentrifugation at 100,000 g for 1 h. About half of the non-sedimentable Zn was non-dialysable, indicating that it was associated with protein, probably non-sedimented casein micelles. Casein micelles incorporated considerable amounts of Zn added to skim milk as ZnCl2, and at Zn concentrations greater than or equal to 16 mM coagulation of casein micelles occurred. Ca was displaced from casein micelles by increasing ZnCl2 concentration and approximately 40% of micellar Ca was displaced by 16 mM-ZnCl2. Micellar Zn, Ca and Pi were gradually rendered soluble as the pH of milk was lowered and at pH 4.6 greater than 95% of the Zn, Ca and Pi were non-sedimentable. These changes were largely reversible by readjustment of the pH to 6.7. About 40% of the total Zn in skim milk was non-sedimentable at 0.2 mM-EDTA and most of the remainder was gradually rendered soluble by EDTA over the concentration range 1-50 mM. This indicates that there are two distinct micellar Zn fractions. No micellar Ca or Pi was solubilized at EDTA concentrations up to 1.0 mM, indicating that both colloidal calcium phosphate (CCP) and casein micelles remained intact under conditions where the more loosely bound micellar Zn fraction dissolved. Depletion of casein micelles of colloidal Ca and Pi by acidification and equilibrium dialysis resulted in removal of Zn, and in colloidal Pi-free milk non-dialysable Zn was reduced to 1.2 mg/l (approximately 32% of the original Zn). Thus, approximately 32% of the Zn in skim milk is directly bound to caseins, while approximately 63% is associated with CCP. Over 80% of the Zn in colloidal Pi-free milk was rendered soluble by 0.2 mM-EDTA, indicating that the casein-bound Zn is the loosely bound Zn fraction in casein micelles. A considerable fraction of the Zn in acid whey (pH 4.6) co-precipitated with Ca and Pi on raising the pH to 6.7 and heating for 2 h at 40 degrees C, indicating that insoluble Zn phosphate complexes form readily under these conditions. Studies on dialysis of milk against water, or dilution of milk or casein micelles with water, showed that CCP and its associated Zn is very stable and dissolves only very slowly at pH 6.6. The nature of Zn binding in casein micelles may help to explain the lower nutritional bioavailability of Zn in bovine milk and infant formulae compared with human milk.

Animals↗
PubMed1989

Effect of procarbazine on sperm morphology in Syrian hamsters.

The effect of procarbazine, an antineoplastic drug, on the reproductive system of male Syrian hamsters was studied. Exposure to procarbazine (5 daily doses ranging from 20 to 500 mg/kg body weight) resulted in 5- to 7.5-fold increase in sperm abnormalities, diminished sperm counts, and smaller testes within 4 wk. Transmission electron micrographs showed severe damage to the acrosomal plasma membrane and nucleus of the sperm head in treated hamsters. These findings corroborate the detrimental effect of procarbazine on the germinal tissue and strengthen the basis for using the sperm morphology assay for the detection of mutagens and possibly other germ-cell toxicants in an in vivo mammalian system.

Animals↗
PubMed1989

Fluid deprivation before operation. The effect of a small drink.

The effect of oral fluids before operation, followed by intramuscular morphine, on gastric volume and pH was examined in 150 elective surgical patients, ASA physical status 1 and 2, who were randomly assigned to one of the three groups of 50 each. Group 1 (control) continued their overnight fast; patients in Groups 2 and 3 received 150 ml water 2 hours before the scheduled time of surgery. Patients in Group 3 received intramuscular morphine 0.15 mg/kg and promethazine 0.5 mg/kg one hour before operation. The residual gastric volume was obtained by suction and its volume and pH measured immediately after induction of anaesthesia. Statistically significant (p less than 0.05) decrease in residual gastric volume was observed in Groups 2 and 3 as compared to Group 1. However, the difference between these two groups was not statistically significant. There was no statistically significant difference in pH among the three groups. Overnight fluid fasting is not justified in elective surgical patients. Morphine can be safely given one hour before surgery in patients who have received water (150 ml) 2 hours before operation.

Adolescent↗
PubMed1989

Mitochondrial and peroxisomal beta-oxidation of stearic and lignoceric acids by rat brain.

Crude subcellular fractions were prepared from adult rat brains by differential centrifugation of brain homogenates. Greater than 98% of the cellular mitochondrial marker enzyme activity sedimented in the heavy and light mitochondrial pellets, and less than 1% of the activity sedimented in microsomal pellets. Lysosomal marker enzyme activities mainly (71-78% of cellular activity) sedimented in the heavy and light mitochondrial pellets. Significant amounts of the lysosomal marker enzyme activity also sedimented in the crude microsomal pellets (9-13% of total) and high-speed supernatants (14-16% of total). The specific activities of microsomal and peroxisomal marker enzyme activities were highest in the crude microsomal pellets. Fractionation of the crude microsomal pellets on Nycodenz gradients resulted in the separation of the bulk of the remaining mitochondrial, lysosomal, and microsomal enzyme activities from peroxisomes. Fatty acyl-CoA synthetase activities separated on Nycodenz gradients as two distinct peaks, and the minor peak of the activities was in the peroxisomal enriched fraction. Fatty acid beta-oxidation activities also separated as two distinct peaks, and the activities were highest in the peroxisomal enriched fractions. Mitochondria were purified from the heavy mitochondrial pellets by Percoll density gradients. Fatty acyl-CoA synthetase and fatty acid beta-oxidation activities were present in both the purified mitochondrial and peroxisomal enriched fractions. Stearoyl-CoA synthetase activities were severalfold greater compared to lignoceroyl-CoA synthetase, and stearic acid beta-oxidation was severalfold greater compared to lignoceric acid beta-oxidation in purified mitochondrial and peroxisomal enriched fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Long latency cutaneous reflex effect on H-reflex recovery in hemiplegics and paraplegics: a longitudinal study for the assessment of motor function.

H-reflex recovery by twin pulses was recorded serially in 10 paraplegics for 5 months and in 23 hemiplegics for 2 months after the lesion. Fifty-one normal subjects acted as controls. The effect of cutaneous tactile stimulation was also studied simultaneously by applying electrical stimuli synchronized with twin pulses to the skin over the lateral border of small toe. In paraplegics, the H-reflex recovery curves recorded serially showed a highly depressed pattern during the first two weeks, an almost normal pattern during the second and third months and a significantly elevated pattern during the fourth and fifth months. Whereas cutaneous stimulation in control subjects produced a highly significant late inhibition of H-reflex recovery between 600 ms and 600 ms, in paraplegics it failed to produce any significant effect, except in two, who besides having a normal H-reflex recovery curve even during the first week, showed a substantial amount of cutaneous inhibition of H-reflex recovery, 4 months after the lesion. A highly depressed pattern of H-reflex recovery was observed on the affected side of the majority of hemiplegics during the first week after the lesion, many of them showing similar pattern on the "unaffected side" also. The serial study showed very good improvement in all hemiplegics both in terms of H-reflex recovery pattern and the amount of cutaneous inhibition. The observations in present study suggest preservation and/or restoration of supraspinal influences in many hemiplegics and in at least two paraplegics. The study also shows that a serial recording of H-reflex recovery curve and the amount of cutaneous reflex effect on it, is a very sensitive method of assessing the supraspinal influences on the spinal motoneurones and so can be of immense help in the diagnosis and prognosis in hemiplegics and paraplegics.

Female↗
PubMed1989

Effect of isoprinosine on lymphocyte proliferation and natural killer cell activity following thermal injury.

The effect of in vivo administration of Isoprinosine (ISO) on, i) the proliferation of splenic lymphocytes in response to the T-cell mitogen, concanavalin-A (Con-A) and, ii) the natural killer (NK) cell cytotoxicity was studied following a full skin thickness burn injury in a rat model. Administration of ISO (100 mg/kg body wt/day) twice daily, resulted in significant augmentation of the proliferative responses of lymphocytes compared to non-treated burned animals, at 7 days post injury. However, it did not effect the lymphoproliferation at 14 days post injury, the time period at which a complete suppression of lymphocyte proliferation was observed in burned non-treated animals. Also, the proliferation of lymphocytes from normal nonburned animals was not affected by treatment with ISO. ISO treatment of the burned animals resulted in a significant increase in the NK cytotoxicity compared to non-treated burned animals. As with Con-A responses, ISO administered to control nonburned animals did not have any effect on NK cell cytotoxicity. Our studies thus indicate that ISO can be a potential immunomodulator of suppressed immune function following thermal injury, particularly in patients whose lymphocyte responses to T cell mitogen Con-A are not completely suppressed.

Adjuvants, Immunologic↗
PubMed1989

Biochemical and genetic studies on degradation of chlorobenzoates by Pseudomonas.

The chlorobenzoates constitute an important class of recalcitrant compounds polluting this biosphere. Two bacterial strains B16 (Pseudomonas aeruginosa) and DT4 (Pseudomonas sp.) isolated by enrichment technique were found to utilize 2-chlorobenzoic acid (2-Cba) and 4-chlorobenzoic acid (4-Cba) respectively as sole source of carbon and energy. 2-Cba and 4-Cba were supplemented in synthetic medium at 1500 micrograms/ml and 1000 micrograms/ml (w/v) respectively. Addition of 100 micrograms/ml (w/v) yeast extract stimulated growth of cultures. Degradation studies revealed that substrates were degraded without release of chloride ion with possible accumulation of respective chlorophenols. Respiration studies revealed inducible nature of enzymes for break down of 2-Cba, 4-Cba benzoic acid, 4-hydroxybenzoic acid and catechol. Extraction of plasmid DNA from parent strains showed presence of plasmid of same size in both strains. Cured strains showed absence of corresponding plasmid DNA bands thus indicating plasmid-borne genes for degradation of chlorobenzoates.

Biodegradation, Environmental↗
PubMed1989

Immunogenicity in monkeys of two polio type 3 seed viruses (SO + 2 and SOR + 1) presently used for production of oral polio vaccine.

Rhesus monkeys were immunized orally and intramuscularly with polio type 3 seed viruses (SO + 2 and SOR + 1). No immune response was detected after oral feeding. Geometric mean titres of 891.4 and 237.02 were obtained after intramuscular administration of six and eight doses of SO + 2 and SOR + 1 respectively. All the monkeys immunized with SO + 2 and SOR + 1 were positive for antibodies after third and fifth dose respectively. High antibody titre (1:1024) was reached in 80 per cent monkeys after sixth dose with SO + 2 whereas this antibody titre was obtained in 20 per cent monkeys after eight doses of SOR + 1. SOR + 1 was found to be a poor immunogen as compared to SO + 2 as it had produced low titre antibody response in monkeys even after administration of eight doses.

Administration, Oral↗
PubMed1989

Experimental colonic anastomosis in bovines--and angiographic study.

4 different methods of colonic anastomosis, single and double layer inversion and eversion, were performed on cowcalves. Hypervascularization of neovascularized arterioles at the cut ends of colon were visualized on the 7th day by all techniques. The arterioles, later one, tended to reorganise towards normalcy. Inversion technique showed better vascularization at the anastomotic site, and the vascular pattern was nearly normal on the 14th and 28th days from surgery. Eversion technique did not exhibit satisfactory revascularization of the anastomotic site on the 7th day of study. A radiopaque area, davoid of arterioles, was noted on the 14th and 28th days from surgery.

Anastomosis, Surgical↗
PubMed1989

Antibodies to extractable nuclear antigens in connective tissue disorders in India: prevalence and clinical correlations.

Antibodies to Extractable Nuclear Antigens (ENAs) namely Sm, nRNP, SS-A and SS-B were studied in 397 patients with various connective tissue diseases (CTD), 146 patients with inflammatory polyarthropathies, 16 cases of systemic vasculitides, and 39 normal subjects using counterimmunoelectrophoresis and double immunodiffusion methods. Anti-ENA antibodies were positive in 40.8 percent cases of Systematic lupus erythematosus (SLE) (n = 191), 36.4 percent of overlap CTD (OCTD, n = 44), 27.8 percent of Sjogren's syndrome (n = 18), 10.6 percent of progressive systemic sclerosis (PSS, n = 66) and 2.7 percent of rheumatoid arthritis (n = 111) patients. The correlation of these antibodies with disease features was done. The significant finding was negative association of anti-nRNP antibodies (when present alone) with renal involvement. Anti-Sm antibodies did not correlate with any disease feature. The other associations included correlation of anti-nRNP with pulmonary parenchymal lesions, anti-SS-A with serositis and pulmonary hypertension, and anti-SS-B with myocarditis and recurrent diarrhoea. We conclude that Anti-ENAs may correlate with certain subsets of these diseases but the subject is controversial.

Adolescent↗