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Biomedical subjects

R Gama

Publications and source records attributed to R Gama.

62 records · Page 4Linked to original sources
PubMed1989

The reduction of peripheral insulin concentrations in obese subjects following a hypocaloric diet: reduced pancreatic secretion or increased hepatic extraction?

The fasting hyperinsulinaemia characteristic of obesity is due to pancreatic hypersecretion and is accompanied by a corresponding increase in plasma C-peptide concentrations. The exaggerated plasma insulin and C-peptide responses to oral glucose in obese subjects which is greater for insulin than C-peptide suggests that the stimulated hyperinsulinaemia is due to both pancreatic hypersecretion and decreased fractional hepatic extraction of insulin. In obese subjects fasting and stimulated insulin concentrations, but not those of C-peptide, are lower after 3 weeks of energy restriction than before it. This reduction in fasting and stimulated insulin levels is, therefore, due to an increase in the fractional extraction of insulin by the liver rather than to a reduction in pancreatic secretion as had previously been supposed.

Adult↗
PubMedDate not supplied

Effect of glucagon on carbohydrate-mediated secretion of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (7-36 amide) (GLP-1).

BACKGROUND: The insulinotropic hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (7-36 amide) (GLP-1), regulate insulin secretion to nutrient intake and constitute the endocrine arm of the entero-insular axis. Glucagon has been implicated in the pathophysiology of conditions characterised by abnormal glucose tolerance such as obesity and diabetes mellitus although its effect on the entero-insular axis is not fully understood. Materials and methods We investigated the effect of exogenous glucagon on the entero-insular axis and its relation to gastric emptying in six healthy men aged [mean (+/-S.E.M. )] 23.6 (0.9) years with a body mass index of 24.0 (1.5) kg/m(2). Plasma glucose, GIP, GLP-1, insulin and paracetamol concentrations were measured before and after a 100 g oral carhohydrate load containing 1.5 g of paracetamol for 6 h during intravenous infusion of either glucagon or saline. RESULTS: When compared to the saline infusion, peak and integrated insulin and glucose concentrations were higher (p<0.05) following glucagon infusion. After 60 min paracetamol concentrations were lower (p<0.05) following glucagon infusion. Integrated responses for GIP and GLP-1 were markedly reduced following glucagon infusion. CONCLUSIONS: Exogenous glucagon in addition to its well-documented action of increasing glucose and insulin concentrations and delaying gastric emptying also markedly reduces GIP and GLP-1 secretion. The inhibition of GLP-1 soon after commencement of glucagon infusion supports a direct effect of glucagon on intestinal L-cells. We speculate that the marked inhibition of postprandial GLP-1 secretion by glucagon may be of importance in the pathogenesis of relative insulinopenia in Type 2 diabetes and in the development of reduced satiety in obesity and diabetes.

Acetaminophen↗
PubMedDate not supplied

[Molecular heterogeneity of prolactin and gonadotropins in some forms of sterility].

In this paper are presented some chromatographic studies for partition of different molecular forms of prolactin (PRL), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in infertile women. Serum from three patients with prolactinoma and six with premature ovarian failure were fractionated in Sephadex G-100, and eighty fractions were collected, where PRL or FSH/LH were measured by radioimmunoassay, according with each case. Patients with prolactinoma showed two different chromatographic patterns for PRL. Two women with secondary amenorrhea and galactorrhea showed predominance of "little" PRL. In contrast, the patients with primary amenorrhea and galactorrhea showed only "big" PRL and "big-big" PRL. Among the patients with premature ovarian failure, two had chromosomal mosaicism, two had refractory ovarian syndrome and the other two had idiopathic premature ovarian failure. In these patients were found the presence of several molecular forms of FSH and LH, with different chromatographic profiles to those observed in normal young women and postmenopausal women. These results are indicating the presence of several molecular forms of pituitary hormones in patients with prolactinoma and premature ovarian failure.

Adult↗
PubMedDate not supplied

[Lyell's syndrome in an AIDS patient].

Toxic epidermal necrolysis (TEN), or Lyell's syndrome, is a rare cutaneous reaction, most often drug related with drugs such as sulfonamides, non-steroidal anti-inflammatory drugs, anti-convulsants and allopurinol. It is characterised by extensive mucocutaneous detachment and usually associated with severe constitutional symptoms. The mortality rate is about 20-66%. The incidence of TEN is increasing among HIV-infected patients, mostly those in an advanced stage of the disease. Although the pathophysiology of TEN is still unclear, data have been reported that support different aetiologies: an immune mechanism, an abnormal pattern of drug biotransformation and a modulating genetic susceptibility. The diagnosis of Lyell's syndrome is mainly clinical because the confirmation of the drug involved is more difficult since there are no safe and reliable skin or in vitro tests that are generally available. THe authors report a case of TEN in a patient with AIDS whose clinical characteristics and evolution are a particular example of this pathology and of the related problems of diagnosis and therapeutics. The fact that this patient presented a prior adverse drug reaction (ADR) besides Lyell's syndrome and a later cutaneous hyperreactivity, raised a complex problem: the risk of reintroducing drugs previously withdrawn due to their possible association with ADRs and the absolute need to treat active disorders. In view of the increased risk of severe cutaneous ADRs, namely TEN, in patients with AIDS, the authors point out the need to set up new guidelines concerning both an early and accurate diagnosis and treatment of these situations and the management of subsequent therapeutics.

AIDS-Related Opportunistic Infections↗