Article Haemostatic parameters PADGEM protein Platelet activation markers Platelet indices Plateletpheresis anticoagulant protein antithrombin comparative study controlled study donor dual specificity phosphatase 2 hemostasis human human experiment mean platelet volume partial thromboplastin time platelet count platelet distribution width protein C protein S prothrombin time thrombocyte activation thrombocytopheresis von Willebrand factor