In vitro measurement of platelet glycoprotein IIb/IIIa receptor blockade by abciximab: interindividual variation and increased platelet secretion.

Background And Objectives: Inhibition of soluble fibrinogen binding to activated platelets represents the target of pharmacologic approach with antagonists of the glycoprotein IIb/IIIa (GPIIb/IIIa) complex. In this study we assessed the effects of abciximab, a recombinant chimeric Fab fraction of the antibody against GPIIb/IIIa, on several markers of platelet activation.

Design And Methods: The platelet surface expression of GPIIb/IIIa was measured by a flow cytometry technique using a two-color assay.

Proteolysis of von Willebrand factor and shear stress-induced platelet aggregation in patients with aortic valve stenosis.

Background: Excessive bleeding may complicate congenital cardiac defects. To explain the pathogenesis of this abnormality, we evaluated selected parameters of primary hemostasis in patients with aortic valve stenosis before and after corrective surgery.

Methods And Results: We examined shear-induced platelet aggregation with the filter aggregometer test and von Willebrand factor (vWF) structure by evaluating the multimeric distribution and extent of subunit proteolysis.

Effect of adenosine derivatives on in vitro thrombus formation induced by shear stress.

Background And Objective: Shear-stress is considered to be the first event of platelet aggregation in vivo and platelet adhesion may be enhanced under pathologic conditions (e.g. arterial occlusion).

Serum von Willebrand factor levels in patients with inflammatory bowel disease are related to systemic inflammation.

Background: Increased levels of circulating von Willebrand factor (vWF) have been found in patients with inflammatory bowel disease (IBD); this increase may reflect either endothelial damage or systemic inflammation. Our aim was to evaluate serum vWF levels in patients with IBD and their correlation with clinical and biochemical disease activity.

Methods: We evaluated serum vWF levels in 32 patients with ulcerative colitis (UC) (10 active with increased acute-phase reactants (APR), 6 active with normal APR, 16 in remission), 27 with Crohn disease (CD) (10 active, 12 quiescent, and 5 quiescent with increased APR), and 31 healthy controls.

Evaluation of the abnormal platelet function in von Willebrand disease by the blood filtration test.

We have evaluated platelet function in different subtypes of von Willebrand disease (vWD) by pushing blood through the capillary-sized channels of a glass filter. Patients, including those with type IIB vWD, showed lower than normal platelet retention and increased cumulative number of blood drops passing through the filter as a function of time. In contrast, shear-induced platelet aggregation, measured in the cone-and-plate viscometer, was paradoxically increased in type IIB patients.