Effect of experimental uremia upon the estrous cycle in rats.

By daily vaginal smears, uremic rats showed significantly greater prevalence of irregular estrous cycles compared with sham-operated controls (p less than 0.02). There seems to be a correlation between the degree of renal failure and estrous cycle abnormalities. The lack of LH surge on the afternoon of proestrus, found in uremic animals, suggests a defect in the positive hypothalamic steroid feedback.

Effect of experimentally induced renal failure upon the fertility in rats. Fertility in uremic rats.

Two groups of rats, one with surgically induced chronic renal failure and a sham-operated group were used. 10 weeks after surgery the animals were individually mated for 15 days according to 4 different schemes: uremic couple, control couple, a couple with a uremic male, and a couple with a uremic female. A second mating was allowed 18 weeks after surgery. There the uremic rats and nonfertile controls were matched against fertile controls. The experimental group showed a higher percentage of nonfertile rats, their offspring had fewer newborns and the uremic mothers had litters that weighed less at birth. In uremic males low plasma testosterone levels were detected. The analysis of plasma luteinizing hormone in the female and the delayed fertilization of uremic mothers suggest the presence of irregularities in the estrous cycle of uremic females.

Evaluation of a sensitive and specific radioimmunoassay for pancreatic glucagon in human plasma and its clinical application.

A glucagon radioimmunoassay employing antiserum specific for pancreatic glucagon is described. Glucagon was radioiodinated by the chloramine T technique and purified on QAE-Sephadex A 25 to a specific activity of 225 mu Ci/microgram. The standard curve allowed measurements from 12 to 500 pg/ml with sensitivity of 17.5 pg/ml, precision of 6.3-14.9% (CV, within-assay) and 5.6-10.7% (CV, between-assay). Recovery was between 82 and 112%. Fasting plasma glucagon levels in diabetics, obese subjects, acromegalics and patients with Cushing's syndrome were greater than in normals (22.0 +/- 91 pg/ml; mean +/- SD). Very low glucagon levels after oral glucose suppression (15.2 +/- 3.1 pg/ml) in normals and greatly increased values after arginine in insulin-dependent diabetics (271.0 +/- 132.3 pg/ml) could be determined.

Absence of zinc testicular deficiency in the sexual dysfunction of experimentally induced uremic rats.

Two groups of adult male rats were used. One group was sham-operated, while the other group had about 70-80% of the left kidney tissue surgically excised and a total right nephrectomy performed 10 days later. Two 15-day mating periods were organized at the 10th and 18th week after surgery. Fertile and infertile rats of the uremic group showed low testosterone levels and increased zinc content of testes in comparison to sham-operated animals. These data contrast with previous reports that zinc deficiency may be a cause of low testosterone values and sexual dysfunction in uremic patients. It is concluded that zinc deficiency may not be involved in the pathogenesis of low testosterone levels and sexual dysfunction in uremic male rats.

Controle de qualidade em radiomunoensaio. / Quality control of radioimmunoassays

Neste trabalho o autor reve os principios basicos que devem estar presentes num Sistema de Controle de Qualidade em Radioimunoensaios alem de discutir as principais causas de erros

Aplicacoes clinicas do radioimunoensaio dos peptidios gastrointestinais. / Clinical application of gastrointestinal peptide radioimmunoassay

O autor descreve os peptideos gastrointestinais de utilidade clinica e faz uma revisao sobre as tecnicas e os testes de radioimunoensaio aplicados na exploracao clinica das principais sindromes decorrentes da alteracao da secrecao destes hormonios

Response of plasma pancreatic and gastrointestinal hormones and growth hormone to oral and intravenous glucose and insulin hypoglycaemia in Chagas's disease.

Plasma hormonal responses to insulin hypoglycaemia and to oral and intravenous glucose were investigated in chagasic patients with severe bowel disease and compared with controls matched for age, sex, weight, and race. After intravenous insulin, plasma concentrations of pancreatic glucagon and pancreatic polypeptide (PP) were reduced in the patients with Chagas's disease. These subjects also showed a subnormal rise in plasma insulin after oral glucose. Other hormone responses did not differ significantly from those in the normal controls. These results are compatible with partial denervation of the pancreatic alpha, beta, and PP cells in patients with chronic gastrointestinal Chagas's disease.

Pectin and complications after gastric surgery: normalisation of postprandial glucose and endocrine responses.

Pectin has been shown to minimise the fall in blood glucose seen in patients who are troubled by hypoglycaemia attacks after gastric surgery. We therefore performed 50 g glucose tolerance tests with and without 14.5 g pectin on 11 post-gastric surgery patients. After pectin, the high postprandial levels of glucose, insulin, and enteroglucagon were significantly reduced as was the fall in blood glucose between 90 and 120 minutes. These effects of pectin may reflect slower uptake of glucose from the gastrointestinal tract and provide evidence to support the use of unabsorbable carbohydrate gelling agents in treating hypoglycaemia after gastric surgery.

Neural and hormonal peptides in rectal biopsy specimens from patients with Chagas' disease and chronic autonomic failure.

The neural and hormonal peptide content of rectal biopsy specimens from 10 patients with chronic autonomic failure, 10 patients with chronic gastrointestinal Chagas' disease, and 13 controls was studied with radioimmunoassay and immunocytochemistry. In the patients with Chagas' disease the mean concentrations of rectal vasoactive intestinal polypeptide, enteroglucagon, substance P, and somatostatin were all less than half of those in controls and in patients with chronic autonomic failure. Immunocytochemistry revealed a considerable reduction in the number and immunostaining of the peptide-containing cells and nerves. Concentrations of regulatory peptides in the rectum are thus reduced in association with intrinsic but not extrinsic autonomic neuropathy.

A study of vasoactive intestinal polypeptide (VIP) stimulated intestinal fluid secretion in rat and its inhibition by indomethacin.

4 groups of rats were studied under anaesthesia to assess the effect of VIP and the influence of the prostaglandin synthetase inhibitor indomethacin in isolated bowel loops. VIP produced a highly significant increase in the luminal fluid content and this was completely inhibited by addition of indomethacin.

Release of gastrointestinal hormones following an oral water load.

The ingestion of 2 different water loads (7.5 and 15 ml/kg) by healthy subjects stimulated the release of plasma motilin, gastrin, pancreatic polypeptide and VIP. Atropine was found to block the release of PP but not the other hormones.

Effect of experimental chronic renal failure upon the synthesis of thyroid hormones in rats.

The authors utilized two groups of adult male rats to study the effect of chronic-uremic toxemia on the synthesis of thyroid hormones. The control group was sham operated, while the other group had about 70--80% of the left kidney tissue surgically excised and a total right nephrectomy performed 10 days later. At the 90th day after the second operation, 8 muCi of 131I were injected intraperitoneally and 24 h later the thyroid was excised and hydrolyzed enzymatically for a period of 14 h at 37 degrees C. The percentages of iodinated components were then calculated after radiochromatographic separation on paper. The group of experimental rats by this time showed significant increases of plasma urea and creatinine, and an absence of acidosis. The results suggest that monoidotyrosine concentration is increased and diiodothyronine decreased in the experimental group of rats with renal failure. This might indicate a toxic metabolic blockage in the transformation of monoiodotyrosine to diiodothyronine.

Renin production in Chagas' disease.

In six controls and ten patients with Chagas' disease (Trypanosomiasis cruzi), plasma renin activity was measured in peripheral venous blood, after 12 hours lying supine, and subsequently in an upright position at 5, 15, 30, 60 and 240 minutes. Evidence of a postganglionic autonomic defect at the sympathetic efferent kidney innervation was observed, probably in two stages corresponding to the clinical form of the disease: The first (asymptomatic or intermediate clinical form) with high renin production and the second with low renin production associated with digestive form of Chagas' disease.

Possible dual role for vasoactive intestinal peptide as gastrointestinal hormone and neurotransmitter substance.

Vasoactive intestinal peptide (V.I.P.) has been found in high concentrations both in the gastrointestinal tract and, unexpectedly, in the central nervous system. Immunocytochemical studies have demonstrated V.I.P. in nerve-fibers. These findings challenge the concept of V.I.P. as a simple gastrointestinal hormone and suggest a possible neurotransmitter function.