The modulatory effect of leptin on the overall insulin production in ex-vivo normal rat pancreas

Leptin has a modulator effect on glucose-stimulated insulin secretion. To define the influences of different glucose (4, 8, 12, and 16 mmol/L) and leptin (5, 10, 15, and 20 nmol/L) concentrations on total insulin release in ex vivo pancreatic preparations, a customized perfusion technique was used. Such a profile of concentration brought about an index for the combined effect of leptin and glucose on the production of insulin. Insulin output was measured by radioimmunoassay. Stimulated by glucose alone in the control group, insulin secretion confirmed a bi-phasic pattern. Addition of leptin in the experimental group suppressed insulin secretion compared with control. A U-shape pattern of suppression was observed when the leptin and stimulatory glucose concentrations were combined. At 12 mmol/L glucose, leptin showed maximal insulin suppression. Leptin’s effect on insulin was glucose dependent and showed a reproducible U-shaped pattern of suppression, which implicated possible direct dose-dependent interaction between leptin and glucose on insulin secretion.

Attenuated GLP-1 secretion in obesity: cause or consequence?

BACKGROUND

Hypersecretion of insulinotropic factors such as glucose dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1(7-36)amide (GLP-1) have been postulated to account for the hyperinsulinaemia of obesity.

AIMS

To examine the role of GLP-1 and GIP in obese women and matched controls.

SUBJECTS

Six lean and six obese women subjects matched for age.

METHODS

The gut hormone, plasma glucose, and serum triglyceride responses were studied over 180 minutes after oral carbohydrate and fat meals. Heparin (10,000 units) was given intravenously at 120 minutes.

RESULTS

There was pronounced attenuation of plasma GLP-1 secretion to oral carbohydrate in the obese compared with lean subjects but no such difference in response to oral fat load. There were no differences in the plasma GIP responses to carbohydrate or fat feeding. There was an apparent fall in plasma GLP-1 values in all subjects after administration of heparin.

CONCLUSION

Postprandial GLP-1 secretion in response to oral carbohydrate is considerably attenuated in obese subjects. The cause of this attenuation of GLP-1 secretion is not known although we suggest that both this fall and the overall reduction in GLP-1 values in obese subjects may be related to an increase in plasma non-esterified fatty acids.

Variation in the process of pediatric asthma care

In May 1994, the continuous quality improvement team at Hermann Children's Hospital in Houston, TX, began to study the structure, process, and outcome of asthma care for pediatric patients. The team's immediate goals were to identify variation in the treatment of pediatric asthma and to determine the most cost-effective interventions. This article details the team's development of a clinical pathway to reduce variation in patient care; use of the pathway led to a reduction in length of stay and a corresponding reduction in costs.

Continuous quality improvement and hospital epidemiology: common themes

Recently, many have begun to explore the possibility of using analytical methods associated with continuous quality improvement in the efforts to improve health care. Central to this paradigm is the proposition that such analytical methods can be used to identify and react to variations in the processes and outcomes of care. These methods and principles are remarkably similar to those employed by hospital epidemiologists. This article explores the similarities between these fields in an attempt to bring together leading thinkers in both disciplines.

Markedly increased platelet membrane fluidity in Down syndrome with a (14q, 21q) translocation

Abnormal platelet membrane fluidity was found in a 50-year-old woman with Down syndrome who had been experiencing a gradual mental decline. The patient's karyotype showed a triplication of the long arm of chromosome 21. The authors hypothesize that the PMF-locus, which carries the allele for increased membrane fluidity, is located on the long arm of chromosome 21. Similarities between Down syndrome and Alzheimer's disease and the possible relationship between membrane fluidity and cognitive function are mentioned.