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Biomedical subjects

A N Peiris

Publications and source records attributed to A N Peiris.

25 records · Page 2Linked to original sources
PubMed1987

Relationship of androgenic activity to splanchnic insulin metabolism and peripheral glucose utilization in premenopausal women.

The importance of androgenic activity in mediating the effects of obesity and body fat topography on splanchnic insulin metabolism and peripheral insulin sensitivity was studied in 19 nonhirsute premenopausal women with a wide range of ideal body weight [percent ideal body weight (% IBW), 78-202%] and body fat distribution pattern [waist to hip girth ratio (WHR), 0.67-0.91]. Turnover kinetics of peripheral plasma C-peptide and insulin were measured, and estimates of pancreatic insulin production (PIP) and the hepatic extraction fraction (HEF) were calculated. The peripheral insulin sensitivity index (M/I) was determined during an euglycemic insulin clamp study. Androgenic activity was assessed by estimating the plasma level of sex hormone-binding globulin (SHBG) and percentage of free testosterone (% FT). After iv glucose stimulation, PIP ranged from 40-254 mU/min X m2 and correlated highly with % IBW (r = 0.78; P less than 0.01). Insulin HEF ranged from 5-69% of the pancreatic production and was inversely proportional to WHR (r = -0.60; P less than 0.01). Increasing WHR also correlated with the diminution in M/I (r = -0.47; P less than 0.05), which, in turn, correlated with the decline in the HEF of insulin (r = 0.60; P less than 0.01). Since PIP, HEF, and M/I correlated with SHBG and % FT, and since the degree of androgenic activity correlated with % IBW and WHR, partial regression analysis was performed. After adjusting for the effects of SHBG and % FT, the relationship between % IBW and PIP remained unaltered, whereas the correlation between WHR and HEF or M/I and their relationship to each other were either markedly reduced or became insignificant. Thus, in premenopausal women, the increase in pancreatic insulin production with increasing weight is independent of the degree of androgenic activity. On the other hand, the decline in hepatic insulin extraction and diminution in peripheral insulin sensitivity with upper body fat localization are in part mediated by increased androgenic activity. This association may account for the pronounced hyperinsulinemia and insulin resistance characteristic of this form of obesity.

Adipose Tissue↗
PubMed1987

Relationship of body fat distribution to the metabolic clearance of insulin in premenopausal women.

The effects of body fat distribution on the metabolic clearance rate of insulin (MCR) and its relationship to peripheral insulin sensitivity (M/I) and androgenic activity were assessed in six nonobese and 20 obese premenopausal women with varying waist-to-hip girth ratio (WHR). As an index of androgenic activity, plasma levels of the sex hormone binding globulin (SHBG) and percentage free testosterone (%FT) were determined. The mean MCR in the obese and nonobese groups were similar (571 +/- 29 vs 578 +/- 31 ml/min/m2). Within the obese group, MCR varied between 401 and 822 ml/min/m2 and was inversely correlated with the WHR (r = -0.50, P less than 0.05). The reduction in MCR with upper body fat localization was observed at both sub- and supra-maximal plasma insulin levels. MCR correlated negatively with fasting and postglucose challenge plasma insulin levels and positively with M/I. MCR also correlated with plasma SHBG and %FT levels. We conclude that upper body fat localization is associated with diminished insulin clearance. This diminution is closely aligned with the degree of peripheral insulinemia and insulin sensitivity. The increase in androgenic activity may contribute to the aberrant insulin clearance observed in upper body obese subjects.

Adipose Tissue↗
PubMed1986

Splanchnic insulin metabolism in obesity. Influence of body fat distribution.

The effects of obesity and body fat distribution on splanchnic insulin metabolism and the relationship to peripheral insulin sensitivity were assessed in 6 nonobese and 16 obese premenopausal women. When compared with the nonobese women, obese women had significantly greater prehepatic production and portal vein levels of insulin both basally and following glucose stimulation. This increase correlated with the degree of adiposity but not with waist-to-hip girth ratio (WHR). WHR, however, correlated inversely with the hepatic extraction fraction and directly with the posthepatic delivery of insulin. The latter correlated with the degree of peripheral insulinemia. The decline in hepatic insulin extraction with increasing WHR also correlated with the accompanying diminution in peripheral insulin sensitivity. Increasing adiposity is thus associated with insulin hypersecretion. The pronounced hyperinsulinemia of upper body fat localization, however, is due to an additional defect in hepatic insulin extraction. This defect is closely allied with the decline in peripheral insulin sensitivity.

Adipose Tissue↗
PubMedDate not supplied

Current therapeutic concepts in diabetic hypertension.

Diabetes mellitus and hypertension are both prevalent in the adult population. The development of hypertension in the diabetic patient is likely to increase the morbidity and mortality in a subgroup already at high risk for atherosclerosis and deserves special consideration. Several studies have confirmed the beneficial effects of antihypertensive therapy on complications such as diabetic nephropathy. This emphasizes the importance of normalizing blood pressure in the diabetic population. It has been suggested that the threshold for initiating antihypertensive therapy should be lower in diabetic patients. All antihypertensive agents have potential disadvantages in patients with diabetes. The commonly encountered effects include deterioration of diabetic control, sexual dysfunction, electrolyte imbalance, and lipid disorders. The adverse effects of these agents on serum lipids have been implicated in the less-than-expected reduction in coronary heart disease noted in some studies. The recent Lipid Research Council study has emphasized the importance of elevated lipid levels and increased cardiovascular mortality. Antihypertensive therapy has advanced rapidly in the last 5 yr. The special problems in the treatment of hypertension within the diabetic population are now receiving greater attention. Undesirable biochemical side effects of drugs used to treat hypertension have become publicized, and the long-term consequences of these abnormalities are under critical scrutiny. The new antihypertensive medications offer exciting alternative approaches to the more traditional agents with less chance of significant metabolic side effects.

Antihypertensive Agents↗
PubMedDate not supplied

Lessons from a doctoral thesis.

The production of a doctoral thesis is a time-consuming affair that until recently was done in conjunction with professional publishing services. Advances in computer technology have made many sophisticated desktop publishing techniques available to the microcomputer user. We describe the computer method used, the problems encountered, and the solutions improvised in the production of a doctoral thesis by computer. The Apple Macintosh was selected for its ease of use and intrinsic graphics capabilities. A scanner was used to incorporate text from published papers into a word processing program. The body of the text was updated and supplemented with new sections. Scanned graphics from the published papers were less suitable for publication, and the original data were replotted and modified with a graphics-drawing program. Graphics were imported and incorporated in the text. Final hard copy was produced by a laser printer and bound with both conventional and rapid new binding techniques. Microcomputer-based desktop processing methods provide a rapid and cost-effective means of communicating the written word. We anticipate that this evolving technology will have increased use by physicians in both the private and academic sectors.

Academic Dissertations as Topic↗