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Biomedical subjects

J C Penhos

Publications and source records attributed to J C Penhos.

At least 37 records · Page 2Linked to original sources
PubMed1975

Metabolic studies in eviscerated rats with functional livers.

A new technique is described for evisceration in the rat in which liver function is preserved. These animals lack all known sources of glucagon and insulin and are capable of active gluconeogenesis, urea formation and ketone body production by the liver. Measurements of blood levels of the metabolites of the caloric substrates showed that, unlike the classical eviscerate preparation, these animals maintain high blood glucose, urea and ketone body levels for up to 72 hr as contrasted with the profound decrease in these constituents in the absence of the liver. Survival time is also significantly extended from about 6 hr in rats lacking liver function to 72 hr or more when the liver is viable. This new surgical preparation is a valuable tool for studying the role of the liver in absence of the known gastroentero-pancreatic hormones. It would also be utilized as a model of "acute" diabetes.

Acute Disease↗
PubMed1975

Glucose tolerance, plasma and pancreatic insulin levels in zinc deficient rats.

Two experiments were conducted to examine the effect of zinc deficiency on glucose tolerance, and on blood and pancreatic insulin concentrations. In the first study, no significant differences in blood glucose or plasma insulin levels were noted between pair-weighted zinc deficient and zinc sufficient rats after an oral glucose load. In the second experiment, the concentration of pancreatic insulin in pair-fed zinc sufficient rats did not differ significantly from that of zinc deficient rats. However, a zinc deficient group fed ad libitum had significantly lower pancreatic insulin levels, suggesting that food restriction may cause increased pancreatic insulin. Thus, zinc deficiency per se had no apparent effect on oral glucose tolerance or pancreatic insulin concentrations.

Animals↗
PubMed1973

Specific biologic effects of intestinal glucagon-like materials.

It has been demonstrated that gastrointestinal extracts contain substances which react immunologically with antibodies prepared to pancreatic glucagon. These extracts have been termed intestinal GLI for glucagon-like immunoreactivity, or enteroglucagon. To determine whether GLI has specific biological effects, studies were designed using the criterion of effect with antiglucagon antibodies. These antibodies did not cross-react with either secretin or pancreozymin. Rat intestinal extracts were prepared and filtered on Sephadex G-50 columns eluted in 0.02 M ammonium carbonate buffer pH 8.8. Two peaks of GLI (I, II) were consistently found, and the in vitro effects of these peaks on two biological systems were tested: (a) immunoreactive insulin (IRI) release by rat pancreas pieces, and (b) free fatty acid (FFA) release and 3',5'-cyclic adenosine monophosphate (cAMP) levels in adipose tissue. Both GLI peaks increased IRI release in the absence of glucose and also enhanced the glucose effects. Antiglucagon antibody suppressed only peak II GLI activity. Both peaks increased FFA release and cAMP levels in adipose tissue. Only peak II GLI activity was suppressed by antibody. These findings support a specific IRI-releasing and lipolytic action for Peak II GLI. Hypotheses are presented concerning the structure and possible physiologic role of peak II GLI.

Adipose Tissue↗
PubMed1970

Studies on the biological activity of porcine proinsulin.

The biological activity of purified porcine proinsulin was investigated in rats. In vivo studies revealed that proinsulin produced a hypoglycemic response similar to insulin but of lesser magnitude. Hypophysectomized and adrenalectomized animals proved to be more sensitive to proinsulin than normal. In vitro studies with rat hemidiaphragm were consistent with the in vivo findings. No competition with insulin action could be demonstrated. Experiments were carried out to determine whether proinsulin is converted to intermediate forms or insulin as a requisite to its biological activity. Labeled proinsulin injected in vivo or incubated in vitro remained intact by a variety of techniques (Sephadex column chromatography and polyacrylamide-gel electrophoresis). An inhibitory action of Kunitz pancreatic trypsin inhibitor on proinsulin action in vitro was confirmed. No clarification of this effect could be ascertained.

Adrenal Glands↗