BACKGROUND AND PURPOSE The purpose of this study was to assess the biological effect of aspirin as measured by the inhibition of platelet aggregation in patients taking aspirin for stroke prevention and in patients with acute stroke. METHODS We administered increasing doses of aspirin (325, 650, 975, and 1,300 mg daily) to 113 patients for stroke prevention and measured the inhibition of plat...

Since imidazole buffers have been used in platelet function tests and the compound has been reported to alter several biochemical activities of platelets, it seemed important to determine whether imidazole influenced platelet aggregation. ADP-induced, collagen-induced, and norepinephrine-induced platelet aggregations were tested in platelet-rich plasma by turbidimetric techniques. Glass beadind...

The Gram-positive bacterium Aerococcus urinae can cause infectious endocarditis (IE) in older persons. Biofilm formation and platelet aggregation are believed to contribute to bacterial virulence in IE. Five A. urinae isolates from human blood were shown to form biofilms in vitro, and biofilm formation was enhanced by the presence of human plasma. Four of the A. urinae isolates caused platelet ...

Adenine nucleotide metabolism and the release reaction were studied during ristocetin-induced platelet aggregation. Decreasing platelet ATP by incubation with metabolic poisons did not decrease ristocetin-induced aggregation. ADP and ATP were released from platelets during ristocetin-induced aggregation, and ATP was converted to hypoxanthine. However, these occurred after aggregation was almost...

Two families with familial exudative vitreoretinopathy were studied in which platelet aggregation defects were found in all the affected members. The major defect observed was absent platelet aggregation with arachidonic acid. In addition platelet aggregation with collagen and adrenaline was reduced in one severely affected member. The implication of the platelet aggregation defect in the patho...

Despite the fact that lysophosphatidic acid (LPA) has been identified as a main platelet-activating lipid of mildly oxidized low-density lipoprotein (LDL) and human atherosclerotic lesions, it remains unknown whether it is capable of activating platelets in blood. We found that LPA at concentrations slightly above plasma levels induces platelet shape change, aggregation, and platelet-monocyte a...

BACKGROUND It is still not clear whether native or platelet count adjusted platelet rich plasma (PRP) should be used for platelet aggregation measurements. AIM To evaluate the necessity of using adjusted PRP in platelet function testing. METHODS Platelet aggregation with native PRP and adjusted PRP (platelet count: 250/nl, obtained by diluting native PRP with platelet poor plasma) was perfo...

Many patients with thrombotic thrombocytopenic purpura (TTP) have a platelet aggregating factor in their serum that may be pathologically linked with the disease process. To help characterize the type of platelet aggregation and platelet release induced by the sera from seven TTP patients, we measured the ability of a variety of inhibitors of platelet function as well as the ability of monoclon...

Despite the fact that lysophosphatidic acid (LPA) has been identified as a main platelet-activating lipid of mildly oxidized low-density lipoprotein (LDL) and human atherosclerotic lesions, it remains unknown whether it is capable of activating platelets in blood. We found that LPA at concentrations slightly above plasma levels induces platelet shape change, aggregation, and platelet-monocyte a...

Ap3A is a platelet-dense granule component released into the extracellular space during the second wave of platelet aggregation on activation. Here, we identify an uncharacterized enzyme, nucleotide pyrophosphatase/phosphodiesterase-4 (NPP4), as a potent hydrolase of Ap3A capable of stimulating platelet aggregation and secretion. We demonstrate that NPP4 is present on the surface of vascular en...