SummaryPlatelet microparticles (MPs) are membrane vesicles shed by platelets after activation, and carry antigens characteristic of intact platelets, such as glycoprotein (GP) IIb/IIIa, GPIb and P-selectin. Elevated platelet MPs have been observed in many disorders in which platelet activation is documented. Recently, platelet GPIb has been implicated in the mediation of platelet-leukocyte interaction via binding to its ligand Mac-1 on leukocyte. The role of GPIb for mediating adhesion-activation interactions between platelet MPs and leukocytes has not been clarified. In this study we investigate the role of GPIb in the interplay between platelet MPs and neutrophils. Platelet MPs were obtained from collagen-stimulated platelet-rich plasma (PRP). In a study model of neutrophil aggregation, platelet MPs can serve a bridge to support neutrophil aggregation under venous level shear stress, suggesting that platelet MPs may enhance leukocyte aggregation, which would bear clinical relevance in diseases where the platelet MPs are elevated. The level of aggregation can be reduced by GPIb blocking antibodies, AP1 and SZ2, but not by anti-CD18 mAb. The GPIb blocking antibodies also decreased platelet MP-mediated neutrophil activation, including b2 integrin expression, adherence-dependent superoxide release and platelet MP-mediated neutrophil adherence to immobilized fibrinogen. Our data provide the evidence for the involvement of GPIb-Mac-1 interaction in the cross-talk between platelet MPs and neutrophils.
This paper explores implementation of MPEG-2 decoding functions (bitstream parsing, IDCT, variable length decoding, motion compensation, dequantization) in software on the TI. TMS32OC6X architecture. We discuss cycle count estimates for these functions; our estimates are based on optimized, functionally accurate implementations in some cases, and on analysis of C implementations of the function in other cases. We describe how we arrive ut these estimates in detail, and discuss how we were able to use automatic compilation effectively for certain functions. We also compure the C6x implementation to other MPEG-2 implementations that have been reported for general purpose CPUs that support a multimedia enhanced instruction set, such as Intel Pentium (MMX), SUN UltraSPARC (VIS), and HP PA (MAX).
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