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Biomedical subjects

M Viswanathan

Publications and source records attributed to M Viswanathan.

At least 145 records · Page 8Linked to original sources
PubMed1988

HLA-D region RFLPs indicate that susceptibility to insulin-dependent diabetes in South India is located in the HLA-DQ region.

Recently close markers for insulin-dependent diabetes mellitus in Western 'Caucasoid' subjects have been defined from DQ region (both alpha and beta genes) restriction fragment length polymorphisms. In order to define the genetic contribution to insulin-dependent diabetes mellitus in an Indian population we have analysed 58 unrelated Dravidian (South Indian) insulin-dependent diabetic patients and 43 controls. In insulin-dependent diabetes an increased frequency of the Taq 1 DQ beta restriction fragment length polymorphisms designated T2 omega/T6 (relative risk = 10.6), and of homozygotes for Taq 1 DQ alpha 4.6 kb (relative risk = 11), was found in the patients. The highest relative risk for insulin-dependent diabetes mellitus was obtained by comparing patients and control subjects who either (a) co-inherited DQT2 omega/T6 with certain DQ alpha restriction fragment length polymorphisms or (b) were DQ alpha 4.6 kb homozygotes, the combination of (a) and (b) accounting for 55.5% of insulin-dependent diabetes mellitus subjects and none of the controls (relative risk = 101; 95% confidence limits 93-109).

Diabetes Mellitus, Type 1↗
PubMed1987

Effects of vagotomy on circulating levels of catecholamines and corticosterone in the pigeon.

The effects of bilateral cervical vagotomy on the blood levels of corticosterone, and catecholamines, adrenaline (A) and noradrenaline (NA), in pigeons, were studied. Plasma levels of corticosterone and NA were found to be significantly higher and of A lower, in the vagotomized (VgX) pigeons as compared to their sham-operated (VgS) controls. These changes in VgX pigeons are explained as caused mainly by the lack of the vagal tone.

Animals↗
PubMed1987

Flight effects on plasma glucose, lactate, catecholamines and corticosterone in homing pigeons.

Significant increase in the circulating levels of glucose, lactate, adrenaline (A) and noradrenaline (NA) was observed in homing pigeons after a flight of 48 km, lasting 60-80 min. There was, however, no change in plasma corticosterone concentrations. The increase in lactate has been attributed mainly to the activity of the white glycolytic fibres in the flight muscles. The increase in A and NA indicated increased sympathetic activity. It is suggested that the flight-induced increase in A stimulated the release of glucagon which could account for the increase in plasma glucose. The lack of any increase in plasma corticosterone implied that the birds were not under any serious stress during the flight and that these results represent the normal changes that may be expected in pigeons during a free flight of the specified distance and duration.

Animals↗
PubMed1987

Exercise- and cold-induced changes in plasma beta-endorphin and beta-lipotropin in men and women.

The plasma beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) response of men, eumenorrheic women, and amenorrheic women (n = 6) to 1 h of rest or to a bicycle ergometer test [20 min at 30% maximum O2 uptake (VO2max), 20 min at 60% VO2max, and at 90% VO2max to exhaustion] was studied in both normal (22 degrees C) and cold (5 degrees C) environments. beta-EP and beta-LPH was measured by radioimmunoassay in venous samples collected every 20 min during rest or after each exercise bout. Exhaustive exercise at ambient temperature (Ta) 22 degrees C induced significant increases in plasma beta-EP and beta-LPH in all subjects as did work at 60% VO2max in amenorrheic and eumenorrheic women. During work at Ta 5 degrees C, the relative increase in beta-EP and beta-LPH was suppressed in eumenorrheic women and completely prevented in amenorrheic women. Although significant lowering of beta-EP and beta-LPH was observed in men and eumenorrheic women during rest at 5 degrees C, amenorrheic women maintained precold exposure levels. These findings suggest that plasma beta-EP and beta-LPH may reflect a thermoregulatory response to heat load. There appears to be a sexual dimorphism in exercise- and cold-induced release of beta-EP and beta-LPH and amenorrhea may be accompanied by alterations in these responses.

Adult↗
PubMed1987

Influence of corticosterone infusion on plasma levels of catecholamines, thyroid hormones, and certain metabolites in laying hens.

Corticosterone was infused continuously through subcutaneously implanted mini-osmotic pumps into laying White Leghorn hens at the rate of 30 micrograms/hr for 14 or 28 days. In both groups receiving corticosterone, plasma levels of glucose and triglycerides were not altered significantly. Circulating levels of cholesterol and free fatty acids increased significantly following both 14 and 28-day infusions of the hormone. Corticosterone treatment for 28 days produced significant increases in plasma levels of thyroxine (T4) and triiodothyronine (T3). However, following the 14-day corticosterone infusion, only T3 showed significant increase. The T3:T4 ratio in both groups of corticosterone-infused hens was significantly higher than in control hens. The concentration of plasma epinephrine showed no significant response to corticosterone treatment, while norepinephrine increased significantly following both periods of treatment.

Animals↗
PubMed1987

HLA-DR and -DQ DNA genotyping in insulin-dependent diabetes patients in South India.

Restriction fragment length polymorphisms (RFLPs) of the HLA-DR beta, -DQ alpha, -DQ beta, and -DX alpha genes have been examined in South Indian diabetic patients and controls. The DR. DQ linkage arrangements in South Indians were shown to be different for DR2, DR4, and DRw6 from those commonly seen in Europeans, so that localization of the primary disease-promoting gene in IDDM could be attempted. This study clearly implicates at least one DQ beta allele in the pathogenesis of IDDM.

DNA Probes, HLA↗
PubMed1987

Pancreatic beta cell response in insulin treated NIDDM patients limitations of a random C-peptide measurement.

Pancreatic beta cell function was evaluated in 30 insulin treated non-insulin dependent diabetic patients, by estimating serum C-peptide after meal stimulation. C-peptide response was low (less than 0.6 pmol/ml) in 15 patients and it was significant (greater than 0.6 pmol/ml) in the other 15 patients. All the patients were then started on a high carbohydrate, high fibre diet and a combination of glibenclamide and metformin. In 18 patients, optimal regulation of hyperglycemia was achieved in one week and the others required insulin treatment. Among the 15 with low C-peptide values, 8 patients responded to oral hypoglycaemic agents and their C-peptide responses improved (from 0.17 +/- 0.16 to 0.78 +/- 0.2 pmol/ml). Among the 15 with significant C-peptide values, 10 responded well to oral drugs and their C-peptide values improved further (from 0.79 +/- 0.21 to 1.17 +/- 0.44 pmol/ml); but the others required insulin despite the good beta cell reserve. This study shows that the beta cell response in insulin treated NIDDM varies widely as it is influenced by the exogenous insulin and hyperglycaemia a random estimation of C-peptide will be of limited value in predicting the response to therapy.

Adolescent↗