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Biomedical subjects

S Schmidt

Publications and source records attributed to S Schmidt.

At least 487 records · Page 27Linked to original sources
PubMed1980

Insulin secretion in maturity-onset-diabetes. Function of isolated islets.

An impaired insulin response to glucose is a characteristic finding in maturity onset diabetes (MOD). To clarify whether the decreased insulin response in vivo is related to a primary defect of the beta-cells, isolated islets of MOD - obtained by intraoperative biopsy - were examined for their insulin content, biosynthesis and release. The in vitro experiments showed that despite a missing or significantly reduced insulin response in vivo the isolated beta-cells of the same patients had a normal insulin content, a normal or even high biosynthesis, and insulin release could be induced by glucose. These results suggest that the primary defect in MoD cannot be related to an intrinsic failure of the beta-cells to response to glucose; extrapancreatic factors seem to influence their reaction to glucose. These factors may be of a higher level in those patients or the reaction of the beta-cells is more inhibited by the same concentrations in diabetic patients.

Aged↗
PubMed1980

Inhibitory effect of intraventricularly applied D-galactosamine on incorporation of labelled precursors into RNA and protein of rat hippocampus.

Ten mumoles of intraventricularly injected D-galactosamine (GalN) inhibited the incorporation of [(3)H]-guanosine and [(3)H]-leucine into RNA and protein of the rat hippocampus, respectively. The inhibition of guanosine incorporation of appr. 80% occurred during the first 30 min after GalN treatment and lasted at least 4 h. The incorporation of leucine was inhibited by appr. 30% only; this effect occurred not earlier than 90 min after GalN injection. The results demonstrate a similar effect of GalN on brain macromolecular syntheses as already observed in the liver suggesting the same mechanism of action, namely trapping of uridine phosphates. The results are discussed with regard to the amnesic effect of GalN observed on the retention of a brightness discrimination in rats.

Animals↗
PubMed1980

Changes in glucose-stimulated insulin secretion after long-term treatment of C57BL mice with glibenclamide.

An insulin response to increased glucose concentrations could not be found in vivo and in vitro after long-term treatment of C57BL/KsJ and C57BL/6J mice with Glibenclamide. This missing stimulation of insulin secretion was not the result of an exhaustion of the islets or a disturbed (pro)insulin biosynthesis as demonstrated by measurements of insulin content of the islets and by in vitro (pro)insulin biosynthesis experiments. In the presence of glucose (15 mmol/l) theophylline increased the insulin secretion of isolated islets of Glibenclamide-treated mice to values similar to control islets. The insulin response to an i.p. glucose loading was found to be normal in comparison with control mice 1-2 weeks after the Glibenclamide treatment had been finished.

Animals↗
PubMed1980

The influence of cultivation on (pro-)insulin biosynthesis and secretion of isolated pancreatic islets of C57BL-mice, long-term treated with glibenclamide in vivo.

Long-term treatment of C57Bl/KsJ and C57Bl/6J mice with glibenclamide in vivo caused a diminished response of insulin to high glucose concentrations (20 mmol/l). Islets of those mice were investigated to answer the question whether it is possible to overcome this diminution of glucose sensitivity by cultivation in presence of high glucose (20 mmol/l). The insulin release of islets of glibenclamide treated mice was significantly lowered also in the first 48 h of cultivation. In the following short-term incubation (2 h) no differences in the glucose stimulated insulin secretion could be seen. The second cultivation period (48-96 h) confirmed these results. Both groups of islets (controls and glibenclamide treated) reached comparable values in insulin release. Cultivation of islets of glibenclamide treated mice in presence of 20 mmol/l glucose for at least 2 days led to a restoration of the glucose sensitivity of insulin release. Insulin biosynthesis, judged by measuring 3H-leucine incorporation into (pro-)insulin, was largely unaffected. In all experimental conditions the insulin content was comparable to that of controls.

Animals↗
PubMed1980

Branching patterns of the hepatic artery in the dog: arteriographic and anatomic study.

Eleven arteriograms, 7 corrosion casts, and 40 dissection studies of 51 clinically normal dogs were examined for the branching patterns of the hepatic artery. An injection of radiopaque medium for selective arteriography was made initially to radiograph the celiac artery, after which a technique defined as superselective arteriography was done, advancing a catheter tip into the hepatic artery. Superselective arteriograms for study of the hepatic artery are described, and the anatomic variants of its branching are discussed. Three major types of hepatic artery branching patterns were identified. The first consists of a single hepatic artery trunk, and this pattern was found in four dogs. The second type with two separate branches of the hepatic artery was found in 27 dogs. The third type was seen in 20 dogs and consisted of 3, 4, or 5 branches that originated directly from the hepatic artery. The origin of the right gastric artery varied, as did the branching of the celiac artery. The most common termination of the celiac artery was as two branches in 31 dogs, and these branches were the hepatic artery and a gastrosplenic trunk. The gastrosplenic trunk subsequently divided to form the left gastric artery and the splenic artery. The usual description of the celiac artery is that it ends by trifurcating. A scheme was developed in which the three major types of hepatic artery branching patterns were outlined. This scheme encompases the hepatic lobar artery variants and can serve as a basis for interpretation of detailed hepatic arteriograms.

Animals↗
PubMed1979

Studies on (pro)insulin biosynthesis and secretion of pancreatic islets of sand rats (Psammomys obesus) after different feeding conditions.

It was possible to induce different metabolic states in sand rats of our breeding colony or in newly caught Egyptian sand rats, respectively, by feeding a pellet diet or vegetable diet (green cabbage). Newly captured sand rats fed only on native food were used as reference group (group C). Plasma IRI-level and glucose in vivo and [3H]-leucine incorporation into proinsulin and insulin, insulin secretion and insulin content in vitro were investigated. Sand rats fed on pellet chow and ad libitum (group B) developed a hyperinsulinism and showed higher sensitivity of [3H]-leucine incorporation into proinsulin and insulin to glucose (maximal stimulation at 3 mM) and increased incorporation rates in vitro. Restriction of pellet food to 35-40 kcal/animal/day (group A) lead to changes of all parameters, which were investigated in the same direction as in group B, but to a much smaller extent. Newly captured sand rats, which were fed green cabbage for 4 to 6 weeks divided into two groups: One group (group D1) was comparable to the normal group (C) in IRI levels, glucose levels, glucose sensitivity and amount of [3H]-leucine incorporation. The other group (group D2) tended to group A. Marked changes in insulin content and insulin secretion of isolated pancreatic islets could not be found in any group.

Animals↗
PubMed1978

Different responses of active and inactive plasma renin to various stimuli.

1. The response of active and inactive plasma renin to orthostasis and frusemide and to inhibition of prostaglandin synthesis by indomethacin was tested in normal human volunteers. 2. Active renin increased by orthostasis and frusemide and decreased by indomethacin. The latter also blunted the increase of active renin after stimuli. 3. Inactive renin was slightly increased by orthostasis, but was not significantly influenced by acute administration of frusemide or inhibition of prostaglandin synthesis by indomethacin. 4. The results show differences in the response of active and inactive renin to stimuli and suppression. Opposite changes of active and inactive renin were not observed in the experimental conditions studied.

Enzyme Activation↗
PubMed1978

Biosynthesis of somatostatin in pancreatic islets of Wistar rats.

Pancreatic islets of Wistar rats were isolated by collagenase digestion and incubated with [3H]-L-phenylalanine. Using a specific somatostatin antiserum radioactivity was found in the antibody-antigen-complex. The radioactivity was displaced by unlabelled somatostatin. These findings give the first evidence for the biosynthesis of somatostatin or somatostatin-like peptides in mammalian pancreatic islets.

Animals↗
PubMed1978

Preparation and characterization of insulin of carp (Cyprinus carpio).

Insulin of carp (Cyprinus carpio) was isolated and crystallized. The insulin was biologically active in two tests; it decreased the blood glucose level and stimulated 14CO2-formation from glucose. The chemical properties are similar to those of insulins from other species. The insulins of carp and of mammals differ greatly immunologically. Antibodies against carp insulin crossreact with carp proinsulin.

Amino Acids↗
PubMed1977

Studies on the (pro) insulin biosynthesis of islets of Langerhans of sand rats (Psammomys obesus).

By feeding a regular laboratory chow, sand rats (Psammomys obesus) from our breeding colony gained different body weights, though they received approximately the same quantity of calories. Sand rats, reaching a body weight above 160 g (group B) showed significantly increased blood glucose values in contrast to the animals with a body weight under 160 g (group A). Isolated pancreatic islets of these two groups of sand rats were incubated with [3H]-leucine to study the incorporation of this amino acid into proinsulin and insulin. The incorporation into proteins of pancreatic islets of sand rats of group B was stimulated by 0.45 mg and 3.0 mg/ml glucose. In group A there was no further stimulation from 0.45 mg to 3.0 mg/ml glucose. Insulin secretion could be stimulated by glucose in both groups, but the stimulation was stronger in group B than in group A.

Animals↗