Differential effect of the GPIIb/IIIa antagonist orbofiban on human platelet aggregate formation in vitro

Racanelli, Adrienne L.; Gibbs, Sandra K.; Zondlo, Susan Carr; Seiffert, Dietmar; Friedman, Steven; Feuerstein, Giora

doi:10.1016/s0049-3848(03)00337-2

Cited by 5 publications

(2 citation statements)

References 19 publications

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“…Calcium chloride (2 mmol/l) was added to isolated rested platelets at 2 × 10 8 /l in TES/Tyrodes/BSA, and 250 μl was prewarmed to 37°C in flat‐bottomed borosilicate tubes (National Scientific, Rockwood, TN, USA; Thermo Scientific, Waltham, MA, USA) containing a cushion of 7·5% polyacrylamide (Osdoit & Rosa, 2001; Racanelli et al , 2003). Clotting was initiated by adding fibrinogen (human) (5 μl at 50 mg/ml) (Enzyme Research Laboratories) and thrombin (bovine) (250 μl at 0·2 U/ml) in TES/Tyrodes followed by brief pipetting.…”

Section: Methodsmentioning

confidence: 99%

WASP plays a novel role in regulating platelet responses dependent on αIIbβ3 integrin outside‐in signalling

et al. 2010

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Summary The most consistent feature of Wiskott Aldrich syndrome (WAS) is profound thrombocytopenia with small platelets. The responsible gene encodes WAS protein (WASP), which functions in leucocytes as an actin filament nucleating agent –yet– actin filament nucleation proceeds normally in patient platelets regarding shape change, filopodia and lamellipodia generation. Because WASP localizes in the platelet membrane skeleton and is mobilized by αIIbβ3 integrin outside‐in signalling, we questioned whether its function might be linked to integrin. Agonist‐induced αIIbβ3 activation (PAC‐1 binding) was normal for patient platelets, indicating normal integrin inside‐out signalling. Inside‐out signalling (fibrinogen, JON/A binding) was also normal for wasp‐deficient murine platelets. However, adherence/spreading on immobilized fibrinogen was decreased for patient platelets and wasp‐deficient murine platelets, indicating decreased integrin outside‐in responses. Another integrin outside‐in dependent response, fibrin clot retraction, involving contraction of the post‐aggregation actin cytoskeleton, was also decreased for patient platelets and wasp‐deficient murine platelets. Rebleeding from tail cuts was more frequent for wasp‐deficient mice, suggesting decreased stabilisation of the primary platelet plug. In contrast, phosphatidylserine exposure, a pro‐coagulant response, was enhanced for WASP‐deficient patient and murine platelets. The collective results reveal a novel function for WASP in regulating pro‐aggregatory and pro‐coagulant responses downstream of integrin outside‐in signalling.

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Section: Methodsmentioning

confidence: 99%

WASP plays a novel role in regulating platelet responses dependent on αIIbβ3 integrin outside‐in signalling

et al. 2010

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“…Recently presented data concerning orbofiban showed that, after in vitro stimulation, large platelet aggregates were blocked, but that small, procoagulant aggregates increased three‐ to sixfold. The data would explain the prothrombotic effects seen in some large trials with oral GP IIb/IIIa antagonists (51). Further, Schwarz et al (52) demonstrated for eptifibatide and physiologic concentrations of fibrinogen a persistence of the GP IIb/IIIa blocker‐induced conformation after fiban dissociation and a partial binding of fibrinogen and the activation‐specific mAb PAC‐1.…”

Section: Discussionmentioning

confidence: 99%