Influence of cytotoxic drugs on platelet functions and coagulation in vitro. IV. Melphalan.

Influence of melphalan on some platelet functions, plasmatic coagulation and fibrinolysis "in vitro" was investigated, using different concentrations of the drug (25, 50 and 250 mug/ml). The lowest concentration slightly inhibited adrenaline and/or collagen-induced platelet aggregation. Following the highest concentration of the drug, strong inhibition of aggregation was recorded, regardless of the inducer used.

Mechanism of calcium-induced reptilase clot retraction.

Calcium ions induce retraction of reptilase clots. This could also be induced by thrombin. Heparin inhibited the reptilase clot retraction induced either by thrombin or calcium, but did not influence the clot retraction induced by ADP.

Reptilase clot retraction test. (Its cofactors and relation to other platelet functions).

C-PRP clotted by reptilase does not retract due to the lack of activation of platelets. In order to support retraction, the platelets must undergo membrane changes resulting in contractile system activation. Only in the presence of aggregating agents capable of eliciting these membrane changes in vitro (e.

Influence of cytotoxic drugs on platelet functions in vitro. III. Peptichemio.

The influence of Peptichemio (m-dichloroethyl-amino-l-phenyl-alanyl-peptide complex) on the following platelet functions was studied: aggregation, release of platelet factor 4, availability of platelet factor 3, acid phosphatases and reptilase clot retraction. Concentrations of the drug corresponding to that found in plasma of treated patients did not significantly influence platelet functions. Concentrations 10 times higher brought about an inhibition.

Bovine fibrinogen-induced 14C-serotonin and other compounds release from human blood platelets.

Bovine fibrinogen can aggregate human blood platelets by a direct mechanism (first wave) and also indirectly by releasing endogenous ADP (second wave). A primarily non-altered surface structure of the thrombocytes is important for the induction of the first wave. Under certain conditions a second aggregation wave, concomitant with the release and the availability reaction is elicited.

A new abnormality of platelet functions. Association of storage pool disease (thrombocytopathia A) with impaired reactivity of platelets to collagen.

Multiple platelet abnormalities were found in a patient with bleeding symptoms. The platelet content of ADP and PF 4 was decreased and the uptake of 14C-serotonin was impaired. The content of acid phosphatase, beta-glucuronidase and beta-N-acetylglucosaminidase was, however, normal and these enzymes were normally released or made available by bovine fibrinogen or ADP.