Biomedical subjects

R Niththyananthan

Publications and source records attributed to R Niththyananthan.

4 recordsLinked to original sources

PubMed1992

Decrease in erythrocyte glycophorin sialic acid content is associated with increased erythrocyte aggregation in human diabetes.

1. Sialic acid moieties of erythrocyte membrane glycoproteins are the principal determinants of the negative charge on the cell surface. The resultant electrostatic repulsion between the cells reduces erythrocyte aggregation and hence the low shear rate viscosity and yield stress of blood. 2. Using g.c.-m.s., a decrease in sialic acid content has been observed in the major erythrocyte membrane glycoprotein, glycophorin A, obtained from nine diabetic patients compared with that from seven normal control subjects [median (range): 3.30 (0.01-11.90) versus 18.60 (3.20-32.60) micrograms/100 micrograms of protein, P less than 0.02]. 3. Erythrocyte aggregation, measured by viscometry as the ratio of suspension viscosity to supernatant viscosity (LS/S) in fibrinogen solution, was increased in ten diabetic patients compared with ten normal control subjects (mean +/- SEM, 37.6 +/- 1.3 versus 33.8 +/- 0.6, P less than 0.02). 4. In the patients in whom both viscometry and carbohydrate analysis were performed, the decrease in erythrocyte glycophorin sialylation and the increase in erythrocyte aggregation in fibrinogen solution were related statistically (LS/S correlated negatively with glycophorin sialic acid content, r = 0.73, P less than 0.05). 5. Decreased glycophorin sialylation provides an explanation at the molecular level for increased erythrocyte aggregation and it may be important in the pathogenesis of vascular disease in diabetes.

Adult↗

PubMed1992

Abnormalities of intermediary metabolism following a gestational diabetic pregnancy.

OBJECTIVE: The aim of this study was to compare intermediary metabolism in glucose tolerant women with previous gestational diabetes and control women without a history of gestational diabetes. SUBJECTS: Fifteen women with previous gestational diabetes and 15 controls individually matched for race, age and body mass index were included. Only subjects with normal glucose tolerance were included in this study. METHODS: Plasma glycerol, 3-OH butyrate, non-esterified fatty acids (NEFA), glucose and insulin were measured fasting and following a 75 g oral glucose load. RESULTS: The women with previous gestational diabetes and their matched controls were of similar racial origin, age and body mass index. There was no difference between those with previous gestational diabetes and controls in fasting glycerol, 3-OH butyrate, NEFA, glucose or insulin concentrations. Following the oral glucose load, glycerol, 3-OH butyrate and NEFA concentrations fell in both groups. However, compared with controls at 120 minutes, those with previous gestational diabetes had significantly higher concentrations of glycerol (median 57, range 24-216 vs 27, range 8-89 mumols/l, P less than 0.005) and 3-OH butyrate (9, range 1-18 vs 5, range 2-11 mumols/l, P less than 0.01). NEFA concentrations were similar in the two groups. Despite similar glucose concentrations during the oral glucose tolerance test the insulin response during the first 60 minutes following oral glucose was significantly reduced in the subjects with previous gestational diabetes when compared with controls (insulin area, 0-60 minutes; 2172, range 788-4767 vs 2830, range 996-4784 pmol min/l, P less than 0.05). CONCLUSIONS: Women with a previous history of gestational diabetes, despite having normal glucose tolerance, have defective insulin release with resultant abnormalities of intermediary metabolism.

3-Hydroxybutyric Acid↗

PubMed1991

The effect of subcutaneous injection site on absorption of human growth hormone: abdomen versus thigh.

OBJECTIVES: To investigate whether growth hormone (GH) absorption is site dependent. DESIGN AND MEASUREMENTS: Human growth hormone (hGH, Norditropin) 4 IU, was injected subcutaneously on two separate occasions: into the thigh on one occasion and into the abdomen on a second occasion. Blood was sampled for GH, insulin, glucose, non-esterified fatty acids and glycerol at baseline and hourly for 12 hours. Serum insulin-like growth factor I was measured at baseline, and after 12 and 24 hours. SUBJECTS: Eleven healthy young adults (8 M, 3 F). RESULTS: Following the injection serum GH had risen by 1 hour and peaked by 3-6 hours. The peak GH and growth hormone area under the curve were significantly higher after injection in the abdomen compared with the thigh (GH peak (mean +/- SEM) 103 +/- 20 vs 41 +/- 8 mU/l, P = 0.002 and GH area 528 +/- 86 vs 239 +/- 34 mU/l h, P = 0.003 respectively). Serum insulin-like growth factor I at 12 and at 24 hours showed a significant rise from the baseline level, but no significant difference was observed between the two injection sites. No significant difference in plasma insulin, glucose, non-esterified fatty acids or glycerol was observed between the two methods of injection. CONCLUSION: Subcutaneously injected GH is better absorbed from the abdominal site than from the thigh.

Abdomen↗

PubMed1979

Comparison of effects of different combined oral-contraceptive formulations on carbohydrate and lipid metabolism.

Oral glucose-tolerance tests were performed and fasting serum cholesterol and triglyceride levels measured in 1628 Caucasian women taking combined oestrogen/progestagen oral contraceptives (o.c.) and 577 women not taking O.C. The former were divided into six groups according to the composition of the O.C Glucose tolerance deteriorated in all O.C. groups containing oestrane progestagens (nortestosterone-derived) or the gonane, norgestrel, but was unaltered by O.C. containing a pregnane progestagen (derived from progesterone). The greatest deterioration was with O.C. containing 75 microgram or more oestrogen, and this was associated with impairment of the early insulin response to glucose. In O.C. containing a pregnane progestagen insulin secretion was unaffected. In the remaining O.C. groups insulin secretion was increased; this was most pronounced with the O.C. containing a gonane progestagen. Serum-cholesterol was elevated only with O.C. containing 75 microgram or more oestrogen and an oestrane progestagen and tended to be lower in O.C. containing a gonane progestagen. O.C.-induced hypertriglyceridaemia was oestrogen-dose-related, and this effect was potentiated by the pregnane progestagen. The gonane progestagen antagonised oestrogen-induced hypertriglyceridaemia.

Adult↗