Hanno Riess

Increased in vitro platelet aggregation in hypertriglyceridemias

Platelet aggregation induced by ADP and collagen was monitored in 25 patients with increased serum levels of triglycerides (7 HLPs type IIb, 14 type IV, 4 type V patients) and compared with a group of 10 normolipidaemic control persons. Platelet aggregation was studied simultaneously in platelet rich plasma (PRP) by both turbidometric and impedance technique and also in whole blood (WB) by the impedance method. Whereas platelet aggregation testing by turbidometry was limited by the optical density of the plasma samples in hypertriglyceridemia, the aggregation process could easily be registered in PRP and WB using the impedance method. Threshold aggregatory concentrations with both agonists were significantly lower for all three groups of HLP.

Effects of BM 13.177, a new antiplatelet drug in patients with atheroscleortic disease

Seven males with atherosclerotic disease received daily 1.6 g of the thromboxane antagonist BM 13.177 in two separate oral dosages over a period of four days. The drug significantly reduced elevated plasma levels of thromboxane B2, beta-thromboglobulin and platelet factor 4, whereas thromboxane B2 generation was only slightly depressed. BM 13.177 inhibited platelet aggregation by collagen, and to a minor degree the second wave of ADP induced aggregation. Platelet sensitivity to prostacyclin and aggregation by ristocetin were not altered. Bleeding time was prolonged. All effects disappeared within 24 hours after the last application of the drug. No side effects were noted. Thus BM 13.177 appears to be a safe and effective new antiplatelet drug.

Unsaturated platelet-activating factor: influence on aggregation, serotonin release and thromboxane synthesis of human thrombocytes.

Unsaturated platelet-activating factor (paf-acether) aggregated thrombocytes of healthy male volunteers like saturated paf-acether. Unsaturated paf-acether released serotonin in the presence of imipramine. Within one minute the release increased depending on the concentrations of unsaturated paf-acether up to 45% of the serotonin. Human thrombocytes synthesized only a small amount of thromboxane B2 (TXB2) after aggregation induced by unsaturated paf-acether. Unsaturated paf-acether prevented the binding of radiolabelled saturated paf-acether to intact washed thrombocytes in the same extent as saturated paf-acether.

Thromboxane receptor blockade versus cyclooxigenase inhibition: Antiplatelet effects in patients

In a randomized pilot study we compared the antiplatelet effects of aspirin and BM 13.177 in two groups of 7 patients each undergoing PTCA. As compared with the pretreatment values template bleeding time was prolonged and collagen induced aggregation was inhibited in PRP and WB in all patients. In the course of angiography and PTCA a rise in platelet factor 4 and beta thromboglobulin was observed in both groups, followed by a decrease below the baseline levels. Thromboxane B2 in plasma and serum decreased in the aspirin group but remained unchanged during BM 13.177 treatment. In PRP and WB aggregation induced by U 46 619 was inhibited after ingestion of BM 13.177 but not following ASA. After three months a control coronary angiography was done. There was no difference in regard to the degree of restenosis between both groups. Medication was well tolerated, compliance was good and no side effects were noted.

Heparin and Thrombocytopenia

Excerpt To the editor: We read with interest the article by King and Kelton (1) on the clinical importance of heparin-associated thrombocytopenia. We wish to make two comments with regard to diagno...