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Biomedical subjects

K Silberbauer

Publications and source records attributed to K Silberbauer.

At least 91 records · Page 5Linked to original sources
PubMed1980

[Age dependence of vascular prostacyclin formation in man (author's transl)].

The synthesis of prostacyclin (PGI2), the most potent known inhibitor of platelet aggregation, varies with age. After 30 years the production decreases, but increases again in the 6th and 7th decade. Contrary to these physiological variations patients suffering from juvenile onset diabetes or peripheral angiopathy show a markedly decreased prostacyclin synthesis. Since the prostacyclin system in thought to be an important blood vessel protector, the pathological low level of PGI2-synthesis could be a key position in development or progression of vascular complications.

Adult↗
PubMed1980

Platelet proteins (beta-TG and PF4) in atherosclerosis and related diseases.

The mean plasma concentrations of beta-TG and PF4 were significantly elevated in patients with diabetes mellitus, peripheral vascular disease and coronary artery disease reflecting enhanced in vivo platelet activity in some of these patients. No correlations could be observed between state of metabolic control and concentrations of platelet specific proteins in diabetic subjects. High mean beta-TG levels were noticed in diabetic patients with increasing severity of retinopathy. Raised beta-TG values decreased significantly after two weeks of treatment with dipyridamole in 10 type-I diabetics. In patients with peripheral vascular disease the WU-test, but not the ADP- or collagen induced platelet aggregation was significantly different between patients and controls, but there were no correlations between the mentioned platelet function tests.

Arteriosclerosis↗
PubMed1980

Effect of experimentally induced diabetes on swine vascular prostacyclin (PGI2) synthesis.

Repeated administration of streptozotocin to Göttingen miniature swine led to the development of a mild form of diabetes. The amount of PGI2 generated by the vessels (abdominal aorta, thoracic aorta, pulmonary artery), as estimated by reference to inhibition of ADP-induced platelet aggregation, was lower in the treated animals than in the controls. The decrease in the synthesis of PGI2 may contribute to the prethrombotic state in diabetes mellitus.

Animals↗
PubMed1980

Influence of proteoglycans (PG) and glycosaminoglycans (GAG) on ADP-, collagen- and thrombin-induced platelet aggregation.

PGs and GAGs have been isolated from fresh bovine aortas according to the method of Hascall and chemically characterized. These PGs and GAGs had only little effects on ADP- and collagen-induced platelet aggregation, but had very potent inhibitory action on thrombin-induced platelet aggregation and prolonged thrombin-clotting-time. Of the standard GAGs investigated hyaluronic acid, chondroitin-4-sulfate and chondroitin-6-sulfate had only little inhibitory action on thrombin-induced platelet aggregation, whereas heparin was very potent in this respect. The unsaturated disaccharides originating after degradation of GAGs with chondroitinases had no effect on platelet aggregation. No differences between PGs and GAGs in inhibiting thrombin-induced platelet aggregation could be detected.

Adenosine Diphosphate↗
PubMed1980

Prostacyclin synthesis in human lymphatics.

The ability of human lymphatics to generate prostacyclin in important amounts (4.5 +/- 2.1 pg/mg/min) is described. The prostacyclin produced, exhibits the same properties as reported for arterial and venous tissue. No age and sex difference could be observed. The role of prostacyclin in physiology of lymphatics, however, is unknown.

Adolescent↗
PubMed1980

The effect of ballooning on minipig aortic prostacyclin formation - a time course.

The effect of a single endothelial injury with an arterial embolectomy catheter on minipig abdominal aorta prostacyclin formation was studied in 17 male animals as a function of time. The normal non deendothelialized abdominal aorta generated 4,41 pg PGI2/mg/min. One hour after endothelial injury PGI2-synthesis was decreased to the half; after two hours no PGI2-production could be detected. After 4 hours the PGI2-generation reached about the half of the strating values being thereafter nearly constant up to 24 hours. This experiment is presented as a model for studying early changes in PGI2-synthesis as it could occur during atherogenesis. The in vitro abrasion of endothelium demonstrated, that about 15% of the total PGI2 are formed by the endothelial sheet. Punching out the tissue samples revealed a strong correlation expressing PGI2-formation in terms of wet weight or surface area respectively.

Animals↗
PubMed1980

Effect of proteoglycans (Pg) and glycosaminoglycans (GAG) on prostacyclin (PGI2) and PGI2-formation of rat arteries.

Heparin had no effect on PGI2-activity if heparin and PGI2 have been incubated-together in an ice bath for 3 minutes. But heparin was able - unlike the other Pg or GAG - to abolish PGI2-activity if it had been incubated with PGI2 in an ice bath for 15 minutes. Pg and GAG, which had been isolated from bovine aortas according to the method of Hascall, and commerically available GAG (hyaluronic acid, chondroitin-40-sulfate, chondroitin-6-sulfate and heparin) had no effect on PGI2-formation of rat aortas in short time incubation (3 min). After long time incubation (15 min) or rat aortas in heparin less PGI2 was detectable compared to a buffer incubation. These data suggest that Pg and GAG do not influence PGI2-formation of arteries. The diminished PGI2-activity after long time incubation should be due to the PGI2-degrading effect of heparin.

Animals↗
PubMed1980

Aortic response to renovascular hypertension.

In the early phase of malignant renal hypertension induced by aortic ligature, a transient activation of transmural aortic permeability is observed. The transmural permeability shows its maximum during the first week of hypertension returning in the third week to normal or even subnormal values, whereas the blood pressure is still rising. The permeability disturbance precedes the structural transformation of the arterial wall. Although the aortic segments above and below the ligature are exposed to different blood pressure and hemodynamic stresses their patterns of permeability disturbance are the same. If the kidney below the aortic ligature is removed no permeability disturbance can be observed. Aortic wall PGI2-formation both above and below the ligature is elevated in the first phase of hypertension. The PGI2-synthesis returns to normal values during the 5th week. Our data suggest that in the early phase of renovascular hypertension there is an increased aortic antiaggregatory activity and that PGI2 is probably not the compound responsible for increased transmural permeability. Moreover, the blood pressure and the hemodynamic forces have no decisive importance in the induction of the aortic transmural permeability disturbance.

Animals↗
PubMed1980

Enhanced prostacyclin synthesis in acute human kidney transplant rejection.

In acute and chronic kidney transplant rejection renal cortical and medullary tissue samples were examined for their prostacyclin (PGI2) generation by bioassay and compared with normal tissue. In acute rejection PGI2 formation was significantly enhanced, particularly in the cortex. In chronic rejection the PGI2 formation was comparable with control tissue. Since PGI2 is a very potent platelet aggregation inhibitor and vasodilator, it is concluded that the increase in PGI2 generation in acute rejection might be a self protecting mechanism which is, however, overwhelmed in irreversible rejection.

6-Ketoprostaglandin F1 alpha↗
PubMed1980

[Interaction between blood platelets and capillary kidney in haemodialysis (author's transl)].

In haemodialysis an interaction between platelets and the dialysator membrane occurs, which is not prevented by heparin. This can be demonstrated by parietal depositions of platelets in the capillaries of the artificial kidney by scanning electron microscopy, as well as in a marked increase of reversible platelet microaggregates during the first phase of dialysis. Some patients are prone to develop thrombosis of the capillary kidneys in spite of a high-dose heparinization. In these cases the use of diclofenac, a cyclooxygenase inhibitor, prevents these adverse platelet reactions.

Adolescent↗
PubMed1979

[Monoclonal gammopathy and platelet function (author's transl)].

This study of 20 patients with monoclonal gammopathy (17 patients with multiple myeloma and 3 patients with Waldenström's syndrome) showed a decreased platlet aggregation induced by ADP and collagen, a reduced platlet retention and a prolonged bleeding time in 25% of the cases in comparison with 30 age- and sex-matched healthy controls. Using Wu and Hoak's technique as increased number of reversible platelet aggregates was observed. There was no relationship between the parameters of primary haemostasis and protein analysis. A disturbed mechanism of primary haemostasis is the main factor responsible for the bleeding diathesis in patients with monoclonal gammopathy.

Aged↗