Detection and quantification of circulating immature platelets: agreement between flow cytometric and automated detection.

Immature platelets-also termed reticulated platelets (RP)-are platelets newly released into the circulation, and have been associated with a variety of pathological thrombotic events. They can be assessed by flow cytometry after staining with thiazole orange (TO) or by using a module added to a fully automated analyzer that is currently in wide clinical use and expressed as a fraction of the total platelet count (IPF). We sought to assess the correlation and agreement between these two methods.

Association of immature platelets with adverse cardiovascular outcomes.

Background: Immature platelets are less responsive to the effects of antiplatelet drugs and contain messenger ribonucleic acid that is translationally active. They can be measured easily using an automated hematoanalyzer and reported as part of the complete blood count.

Objectives: The purpose of this study was to determine the prognostic significance of elevated immature platelet count (IPC) in patients with coronary artery disease (CAD).

Immature platelet fraction (IPF) determined with an automated method predicts clopidogrel hyporesponsiveness.

The mechanisms for the variability in antiplatelet effects of clopidogrel are not elucidated entirely. Immature (reticulated) platelets may modulate the antiplatelet effects of clopidogrel but must be measured using flow cytometry. Whether new automated detection techniques yield similar results is not known.

Platelet reactivity and response to aspirin in subjects with the metabolic syndrome.

Background: Metabolic syndrome (MS) is associated with a prothrombotic state and predicts the subsequent development of type 2 diabetes mellitus. We hypothesized that similar to diabetes, subjects with MS may have increased platelet reactivity, and reduced response to aspirin. We, therefore, compared platelet reactivity and response to aspirin among subjects with MS and healthy volunteers.

Role of reticulated platelets and platelet size heterogeneity on platelet activity after dual antiplatelet therapy with aspirin and clopidogrel in patients with stable coronary artery disease.

Objectives: The aim of this study was to evaluate the relationship between reticulated platelets (RPs), platelet size, and platelet function in patients with stable coronary artery disease (CAD) taking aspirin and clopidogrel.

Background: Reticulated platelets are young platelets that are larger and possibly more active than non-RPs.

Methods: Flow cytometry was used to measure RPs after staining with thiazole orange and to define the upper 20% and lower 20% of platelets by size.

Increased platelet sensitivity among individuals with aspirin resistance - platelet aggregation to submaximal concentration of arachidonic acid predicts response to antiplatelet therapy.

Aspirin 'resistance' (AR) is a phenomenon of uncertain etiology describing decreased platelet inhibition by aspirin. We studied whether (i) platelets in AR demonstrate increased basal sensitivity to a lower degree of stimulation and (ii) platelet aggregation with submaximal stimulation could predict responses to aspirin. Serum thromboxane B(2) (TxB(2)) levels and platelet aggregation with light transmission aggregometry (LTA) were measured at baseline and 24 hours after 325 mg aspirin administration in 58 healthy subjects.

Effect of ranitidine on the antiplatelet effects of aspirin in healthy human subjects.

Aspirin is often taken with H2-receptor antagonists. In vitro data suggest that certain antagonists, such as ranitidine, have inhibitory effects on platelet function. There are no reports on the combined effect of aspirin and H2-receptor antagonists on platelet function in humans.

Platelet reactivity in patients with subacute stent thrombosis compared with non-stent-related acute myocardial infarction.

Background: Recent case control studies suggest that patients with subacute stent thrombosis (SAT) have increased platelet reactivity. However, SAT often presents as acute myocardial infarction (AMI), which is also associated with augmented platelet activation. We therefore compared platelet reactivity in patients with SAT and patients with AMI unrelated to stenting.

Aspirin and clopidogrel drug response in patients undergoing percutaneous coronary intervention: the role of dual drug resistance.

Unlabelled: We evaluated the response to clopidogrel among aspirin-resistant versus aspirin-sensitive patients undergoing elective coronary stenting. Patients (n = 150) treated with aspirin but not clopidogrel had blood samples drawn at baseline and 24 h after clopidogrel loading. Depending on the definition used, 9% to 15% were resistant to aspirin and 24% to clopidogrel.