apyrase and Hemolysis

Poor haemocompatibility of material surfaces is a serious limitation that can lead to failure of blood-contacting devices and implants. In this work, we have improved the haemocompatibility of polyethylene terephthalate (PET) surfaces by immobilizing apyrase/ecto-nucleoside triphosphate diphosphohydrolase (NTPDase) on to the carboxylated PET. NTPDase immobilized PET surfaces scavenge the ADP released by activated platelets, which prevents further platelet activation and aggregation. The surface properties of the modified PET were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDAX), and contact angle measurement. The enzyme attachment and stability on the modified PET surfaces were evaluated. The kinetics of free enzyme and immobilized enzyme were studied and fitted using the Michaelis-Menten kinetic model. Both free and immobilized NTPDase followed Michaelis-Menten kinetics with similar Michaelis-Menten constants (K

Topics: Adsorption; Antigens, CD; Apyrase; Biofouling; Enzymes, Immobilized; Hemolysis; Humans; Kinetics; Materials Testing; Polyethylene Terephthalates; Surface Properties

Thromboembolic complications significantly impair the outcome of hemolytic disorders. We hypothesized that red cell adenosine diphosphate (ADP) release results in significant platelet activation in hemolysis and that this prothrombotic state can be prevented by inhibition of the ADP P2Y

Topics: Adenosine Diphosphate; Adult; Aged; Apyrase; Blood Group Incompatibility; Blood Platelets; Clopidogrel; Female; Hemolysis; Humans; Male; Middle Aged; Platelet Activation; Platelet Glycoprotein GPIIb-IIIa Complex; Receptors, Purinergic P2Y12; Ticlopidine

Effects of ethanol on blood clotting and platelet aggregation have been reported in many models, but its in vitro actions in whole blood, impedance aggregometry have not been reported. We investigated the effect of ethanol in vitro in whole blood and platelet rich plasma of humans and rats, as measured by impedance aggregometry. Ethanol (34 to 170 mM) induced concentration-dependent aggregation in whole blood but not platelet rich plasma. In further studies in rats, aggregation was inhibited by pretreatment of whole blood with the prostacyclin analog iloprost or the enzyme apyrase, which degrades ADP to AMP. Levels of ethanol which produced aggregation in whole blood were also associated with concentration-dependent hemolysis. Based on the requirement for whole blood for ethanol-induced aggregation, the inhibitory effect of apyrase and our observation of hemolysis, and previous studies which have demonstrated the potential contribution of ADP from lysed red blood cells to platelet aggregation, we conclude that ethanol-induced aggregation in whole blood is mediated by erythrocyte lysis and the ADP released from these cells.

Topics: Adenosine Diphosphate; Animals; Apyrase; Collagen; Ethanol; Female; Hemolysis; Humans; Iloprost; In Vitro Techniques; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Rats, Inbred Strains

Rabbit hemolysate-loaded microcapsules having sulfonic acid groups on their surface were prepared and rabbit platelet adhesion onto the sulfonated surface was examined kinetically. Rabbit platelets adhered more markedly onto the surface of a higher charge density than that of a lower one, indicating a trend similar to that found in the case of the surface having carboxyl groups. Moreover, the platelets were found to be stickier in the buffer solution than in the plasma, though the dependence of platelet adhesion in the buffer solution on the magnitude of surface charge of the sulfonated artificial red blood cells was still recognized.

Topics: Adenosine Diphosphate; Animals; Apyrase; Blood Substitutes; Hemoglobins; Hemolysis; Kinetics; Nylons; Platelet Adhesiveness; Platelet Aggregation; Rabbits