Brewer's yeast was grown on a defined medium containing glucose, ammonia, salts and vitamins plus tracer 51Cr without (low-Cr) or with (high-Cr) carrier Cr. The two batches of yeast differed by more than 100-fold in Cr content, containing 80 ng and 10 7mu;g Cr/g dry yeast respectively. Extraction and fractionation procedures were designed to isolate Cr complexes with properties similar to those reported for glucose tolerance factor. After weaning, rats were reared on rat cubes (normal diet) or on a diet containing less than 0.1 μg Cr/kg (low-Cr diet), or on the low-Cr diet supplemented with Cr (1 mg Cr/kg). Hepatocytes from these rats were incubated with [U-14C]glucose and incorporation of 14C into glycogen was measured. Incorporation of glucose-C into glycogen was enhanced by some yeast fractions in the presence of insulin, but had less effect in the absence of insulin. No difference could be detected between the responses to fractions from high- or low-Cr yeast extracts, or between responses by hepatocytes from animals fed on normal or low-Cr diets with or without Cr upplementation. Glycogen synthetase (EC 2.4.1.11) activity (total and percentage in the a form) was similar in hepatocytes isolated from animals on the normal and low-Cr diets. Those yeast fractions which enhanced the response to insulin in the 14C-incorporation experiments also enhanced the percentage of the enzyme in the a form in the presence of insulin, but not in the absence of insulin. The presence in yeast extracts of material which enhances the response to insulin by hepatocytes may help to explain the reported beneficial effects of dietary yeast supplements on glucose tolerance.

The case is described of a 61-year-old male who presented with hypertension and Cushing's syndrome which resolved on excision of a unilateral adrenal mass. Histology of the tumour revealed a benign phaeochromocytoma which immunostained for corticotrophin-releasing factor (CRF-41) but not for ACTH. Preoperative plasma concentrations of immunoreactive CRF-41 were increased, and gradients for both CRF-41 and ACTH were demonstrated across the tumour. Post-operatively, CRF-41 was undetectable in plasma. The tumour contained high concentrations of immunoreactive CRF-41 which co-eluted with synthetic human CRF-41 on reversed-phase high-performance liquid chromatography. Tumour CRF-41 stimulated the release of ACTH in a dose-dependent manner from isolated rat anterior pituitary cells. We conclude that this tumour secreted CRF-41 and ACTH and had the capacity to produce ACTH-dependent Cushing's syndrome directly by secreting ACTH and indirectly by secreting CRF-41 to stimulate ACTH secretion from the anterior pituitary.

Brues et al. (1) have shown that the regenerating rat liver is affected by various dietary conditions. They found that when the weight of the liver was measured after partial hepatectomy, liver regeneration decreased in rats fed diets high in carbohydrate or protein and in starved .rats but not in rats fed a hi.gh fat diet. However, when the number of nuclei in the regenerating liver was measured, only a slight decrease was noted in the rats fed a high carbohydrate or high protein diet, while a significant decrease was found in the rats fed a high fat diet. Rats that were starved up to 4 days showed no differences in nuclei number when compared to fed mimals.The above data were collected from rats 2 to 4 days after partial hepatectomy. In our laboratory, we have been concerned more with the earlier time periods following partial hepatectomy, namely, 20-36 hr, during which mitosis is initiated and reaches a maximum value. The present experiment was designed to investigate whether early mitotic activity in the liver following partial hepatectomy is affected when rats are fed diets high in carbohydrate, protein, or fat for 7 days and when starved 24 hr. Also studied was the effect of these dietary conditions on the mitotic activity of the intact liver from unoperated rats.Methods. Four-week-old male Sprague-Dawley rats weighing 85-90 g were fed various diets for 7 days. The diets, purchased from Nutritional Biochemicals Corp., varied only in percentage composition of protein, fat, and carbohydrate and were supplemented with vitamin and salt mixtures. The four test diets, fed ad libitum to 4 different groups of rats, were normal (2770 casein, 59y0 starch, 10% vegetable oil), high protein (64% casein, 22% sucrose, 8% vegetable oil), high carbohydrate (18% casein, 68% sucrose, 8% vegetable oil), and high fat (18% casein, 29% sucrose, 45% vegetable oil). A fifth group of rats was fasted for 24 hr after being fed the normal diet ad Zibitum for 7 days.Because of the low caloric intake of rats fed the high protein and high fat diets, the normal diet was given to a sixth group of rats, whose caloric intake was restricted so that it was comparable to that of the rats on the high protein an'd high fat diets. The caloric intake of the rats maintained on the latter two diets was 65% and 7576, respectively, that of the rats fed the normal diet ad lib;turn. The caloric intake of the rats fed the high carbohydrate diet was less but did not differ significantly from that of the rats maintained on the normal diet ad libitum.The rats were kept in individual metabolic ca,ges in an air conditioned room with fluorescent lighting automatically set for on-off cycling at 6:OO a.m. and 6:OO p.m., respectively. Food and water were given ad libitum to all rats except the calorically restricted control rats, which received only water ad libiturn. The calorically restricted rats, were fed in the late afternoon in order to minimize any differences in the eating patterns between these rats and the rats fed ad libitum.After the 7 day dietary per...

Animals are frequently anesthetized prior to blood collection or tissue sampling to expedite handling. Nembutal,2 a drug containing sodium pentobarbital as the active anesthetic agent, is popular for such purposes.In this laboratory, it became necessary to institute special bleeding procedures. Rats were anesthetized with Nembutal, the abdominal cavity was opened, and blood was removed by needle puncture of the aorta. By happenstance, it was found that plasma free fatty acids were lower and plasma glucose higher in the special treated rat than the values normally found in decapitated rats. It was not readily apparent whether the differences were related to the method of blood collection, animal variation, or to the anesthetic agent. The following experiments are a follow-up of these observations and describe changes that occurred in plasma glucose and free fatty acids as a result of Nembutal injection.Methods. Male Sprague-Dawley rats (240-255 g) were fed ad libitum and allowed free access to water until initiation of the experiment. The rats were anesthetized by injection of 25 or 50 mg/kg of body weight of sodium pentobarbital (Nembutal) ip in a volume of approximately 0.25 ml. Nonanesthetized control rats were treated in one of three ways: (i) noninjected; (ii) injected with 1 ml/kg of body weight of 0.9% saline ip; or (iii) injected with 1 ml/kg of body wt of the Nembutal vehicle ip, which consisted of 10% ethanol, 20% propylene glycol, and 70% distilled water by volume and adjusted 1 Research Associate National Academy of Science. 2 Trade name, Abbott Laboratories. to pH 10.5 with NaOH. All injections were between 0900 and 0945 hr, and the rats were sacrificed at various time intervals up to 4 hr thereafter. Blood was collected in heparinized syringes via abdominal aorta puncture or in heparinized tubes after decapitation. All nonanesthetized control rats were decapitated. Plasma glucose was determined by the glucose oxidase method (1) and plasma free fatty acids (FFA) by the method of Trout et d. (2). The level of significance was p<.O5 using a multiple t test. Tn the time course studies, the p value as determined by the t test was confirmed by the analysis of variance using the method of Scheffi (3 ) .

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