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E Verspohl

Publications and source records attributed to E Verspohl.

9 recordsLinked to original sources
PubMed1989

Insulin receptor monoclonal antibodies that mimic insulin action without activating tyrosine kinase.

HTC rat hepatoma cells were transfected with human insulin receptor cDNA to a level of 40,000 receptors/cell. In these cells, as well as in nontransfected cells, insulin stimulated the uptake of alpha-aminoisobutyric acid. Two monoclonal antibodies directed against the human insulin receptor alpha subunit, like insulin, stimulated amino acid uptake in transfected HTC cells, but not in nontransfected HTC cells. The antibodies, in contrast to insulin, failed to stimulate insulin receptor tyrosine kinase activity, both in intact transfected cells and in cell free extracts prepared from them. These data suggest, therefore, that activation of insulin receptor tyrosine kinase may not be an obligatory step in all of the transmembrane signaling mechanisms of the insulin receptor.

Aminoisobutyric Acids↗
PubMed1978

[A method for radio-immunological determination of g-strophanthin (author's transl)].

For the purpose of estimating g-strophanthin radio-immunologically the following steps are described: the preparation of g-strophanthin antigen, the production of antibodies in the rabbit, the presentation of calibration curves, and the possibility of a quantitative determination of heterogenous glycosides. According to Malaprades reaction, g-strophanthin adheres to human albumin. With this antigen thus obtained antibodies are produced in rabbits. For the presentation of calibration curves, the addition of antiserum and g-strophanthin have to be matched in quantity; the calibration curves correspond to mathematical data. An increased sensitivity of the method is possible to attain by reducing the amount of labelled antigen and antiserum. The slight cross-reactivity of antibodies can be used to determine other glycosides when these are incubated labelled with tritium instead of 3H-g-strophanthin.

Animals↗
PubMed1977

6-Phosphogluconate/glucose-6-phosphate ratio in rat pancreatic islets during inhibition of insulin release by exogenous insulin.

Inhibition of glucose-stimulated insulin release by exogenous insulin has been demonstrated in pancreatic islets to be associated with a decrease of the NADPH/NADP ratio and the pentose-phosphate cycle activity. Batches of five islets were incubated for 15 and 90 minutes in 1 ml. of KRB buffer with 2 per cent albumin containing 3 mg./ml. glucose and 0, 200, 400, or 800 microU./ml. of rat insulin, and the glucose-6-phosphate (G6P) and 6-phosphogluconate (6PG) contents were determined by enzymatic cycling. In response to a rise in the concentration of insulin, the 6PG/G6P ratio decreased. A close relationship was observed between this decrease of 6PG/G6P ratio and the net insulin release, the absolute rate of glucose oxidation via the pentose phosphate cycle, and the NADPH/NADP ratios measured under similar conditions. The results suggest that exogenous insulin, directly or indirectly, regulates the pentose cycle activity in the pancreatic islets at the G6P dehydrogenase step.

Animals↗
PubMed1976

Pyridine nucleotides in pancreatic islets during inhibition of insulin release by exogenous insulin.

In vitro addition of rat insulin (200, 400 or 800 muU/ml) to collagenase-isolated pancreatic islets of adult rats diminished glucose (3 mg/ml)-induced insulin release which was correlated with a decrease of the ratio of total NADPH/NADP and inhibition of glucose oxidation via the pentose phosphate shunt (PPS). NADH and NAD levels were not affected. It is suggested that exogenous insulin diminishes the islet total NADPH/NADP ratio by a direct or indirect decrease in PPS activity. However, it is also conceivable that insulin decreases this ratio through another mechanism than PPS. It is possible that inhibition of insulin secretion by exogenous insulin is at least in part due to the decrease of the NADPH/NADP ratio.

Animals↗