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Biomedical subjects

S Knospe

Publications and source records attributed to S Knospe.

48 records · Page 3Linked to original sources
PubMed1976

Glucose-induced insulin secretion and insulin sensitivity of peripheric organs of Egyptian sand rats before manifestation of diabetes.

In Egyptian sand rats (Psammomys obesus) fed with native food and a low caloric vegetable diet after capture it was possible to study endocrinologic and metabolic changes of the early stages during the progression to diabetes. According to body weight gain and fasting blood glucose the animals were differentiated into two groups classified as basic and protodiabetic group, respectively. Isolated pancreatic islets as well as the perfused pancreases of sand rats responded to low concentrations of glucose with high insulin release during early stages of the development to diabetes. Changes in the insulin content of the islets could not be detected at this time although in the B-cells of the protodiabetic animals a degranulation was visible. During these early stages of the development to diabetes the in vitro insulin action on glucose utilization in soleus muscle and especially in epididymal fat pads as well as the basal glucose metabolism in adipose tissue were low. This strikingly reduced utilization of glucose by adipose and muscle tissues may be a factor which challenges the B-cell.

Adipose Tissue↗
PubMed1975

[Streptozotocin diabetes in the rat with special reference to glucose utilization by the musculature].

The glucose utilization by different skeletal muscle tissues of short-term streptozotocin treated Wistar rats was studied both in vivo and in vitro. The findings permit the following statements: The reduced metabolic conversion of glucose is mainly the result of the diminished transport of glucose into the muscle cells. The utilization of the glucose taken up by the muscle cells for synthesis of glycogen is unchanged in the diabetic animals and can be stimulated by insulin correspondingly as in normal rats. The conversion of the glucose metabolized by the cells to lactate and the time course of the specific activity of glycogen and lactate lead to the conclusion that glycogenolysis in the muscles of streptozotocin diabetic rats during the incubation is enhanced.

Animals↗
PubMed1971

Fraktionierung handelsüblichen insulins. Gewinnung und eigenschaften einer hochmolekularen, insulin-ähnlichen komponente.

A component with high molecular weight is prepared from commercial bovine insulin by gel filtration on Sephadex G 50. The substance has little biological and immunological activity in comparison to insulin. The activity is not changed by incubation with trypsin. It associates in 1 M CH(3)COOH and possesses a molecular weight of 28,500 as shown by ultracentrifugation. The ability of the component to precipitate with bovine insulin antibodies demonstrates that it contains immunologically active insulin-like proteins and is not a homogenous substance.

Journal Article↗
PubMedDate not supplied

Relationship between carbohydrate tolerance, insulin secretion, and insulin sensitivity of isolated fat cells from obese protodiabetics.

Six normal weight subjects without any heredity of diabetes (group 1), 3 obese subjects with normal (group 2) and 9 with pathological carbohydrate tolerance (group 3) were characterized by a 2-h glucose infusion test. Adipose tissue fragments were obtained from the abdominal wall by surgical biopsy under intracutaneous anesthesia. Adipocytes were isolated by collagenase digestion and incubated in buffer containing [1-14C] glucose and different concentrations of insulin. The metabolic effect of insulin was expressed as percent increase above control 14CO2 production. Maximal CO2 raised to 207 +/- 25% and 154 +/- 9% in groups 1 and 2, respectively. These values were significantly higher than in obese subjects displaying a pathological carbohydrate tolerance (group 3; 119 +/- 6%). A negative correlation was found between blood glucose levels and biological activity of insulin on adipocytes. The results suggest that insulin sensitivity of target tissue seems to play an important role in development of carbohydrate intolerance.

Adipose Tissue↗
PubMedDate not supplied

Relationship between body fat mass, carbohydrate tolerance and IRI response during glucose infusion in subjects with early diabetes.

We have studied the interrelationship of total body fat mass, carbohydrate tolerance and IRI response in 17 non-obese and obese subjects, who were suspected of having early diabetes. We carried out an i.v. glucose infusion test consisting of a priming injection of 0.33 g/kg followed by constant glucose infusion of 12 mg/kg/min in all persons. Total body fat mass was estimated by the tritium dilution method. There was a positive correlation of body fat mass, fasting glucose concentration and blood glucose concentration at 150 min as well as a strong correlation between body fat mass and BG area 60--120 min as parameters of carbohydrate tolerance in all subjects, i.e. the degree of carbohyrate intolerance was directly related to the quantity of total body fat mass. A similar correlation was found when the non-obese and obese groups were analyzed separately. In neither group did total body fat mass correlate with parameters of IRI response. In obese subjects with pathological carbohydrate tolerance, however, a positive correlation of basal IRI concentration and total body fat mass was found. Furthermore, a close relation between basal IRI level and parameters of carbohydrate tolerance could be demonstrated in obese subjects. The present study failed to demonstrate any correlation of parameters of carbohydrate tolerance and glucose-induced IRI response in either group. Thus, the significant relationship between body fat mass and degree of carbohydrate intolerance indicates that body fat mass plays an important role in the disturbance of blood glucose homeostasis in early diabetes with and without obesity.

Adipose Tissue↗
PubMedDate not supplied

Insulin responsiveness of adipose tissue from normal weight subjects with early diabetes.

In normal weight subjects, classified by a 2-h glucose infusion test as having normal (11), borderline (3) or pathological (9) carbohydrate tolerance (CHT), subcutaneous adipose tissue was removed under intracutaneous anesthesia by surgical biopsy. The biological responsiveness of isolated adipocytes as well as adipose tissue fragments measured as incorportion of (1-14C) glucose into CO2 or triglycerides was studied in the absence or presence of different insulin concentrations. In persons with normal CHT the insulin-stimulated (62.5 microU/ml) glucose conversion to CO2 by adipocytes as well as fat pads increased significantly up to 156 +/- 14% and 285 +/- 30%, respectively. Insulin enhanced the glucose incorporation into triglycerides up to 154 +/- 20% (fat cells) and 258 +/- 30% (fat pads) in adipose tissue from subjects displaying a normal CHT. Rates of glucose oxidation and triglyceride synthesis was markedly reduced in adipose tissue obtained from patients with borderline or pathological CHT. A significant positive relationship was found between glucose oxiation to CO2 and triglyceride production of fat cells and fat pads (r = 0.964 and 0.783, respectively). There was no correlation with responsiveness of adipose tissue to insulin and insulin secretion during glucose infusion test. The results indicate that sensitivity to insulin of target cells might be important for the development of carbohydrate intolerance also in normal weight subjects.

Adipose Tissue↗