Platelet microaggregate

Increased margination of leukocytes in the circulation of the lung through adhesion to the pulmonary endothelium and formation of platelet microaggregates have been postulated as important components in the etiology of... 

As the clinical use of blood-pumping devices has increased, and surgical procedures involving extended extracorporeal circulation have become widespread, the effects of these procedures on formed elements of the blood have become clinically important. Among the better studied trauma-induced effects on blood is that platelet microaggregates may form, sometimes in conjunction with small clumps of PMNs, followed by sequestering of these elements in the microvasculature (particularly that of the lung). The release of lysosomal enzymes and vasoactive substances from platelets and PMNs... 

Earlier work in this laboratory and others demonstrated in vitro dysfunction of both platelets and leukocytes following application of low-level shear stress (1 4). The effects of mechanical trauma can be attributed to bulk shear stress effects rather than surface-mediated ones, since changing the surface-to-volume ratio by a factor of three did not alter the leukocyte or platelet response to a given shear stress intensity and exposure duration (2). Platelet microaggregate formation and adhesion alterations occurred following shear stress exposure in the range of 150 dyn/cm2 for 2 min, while... 

Laser Light Scattering Detection of Microemboli. To elucidate the mechanism of platelet destruction by grafted polyacrylamide-Silastic surfaces, an optical scattering technique was developed (20) to observe and quantitate the sizes and size distributions of microaggregates in blood produced within the AV baboon shunt. Presumably, any such flowing microaggregates represent platelet microemboli. 

For example, the volume of microaggregates flowing through the cuvette at any time can be estimated from the size distribution, assuming that the microaggregates are composed of close-packed spherical platelets and that the emboli are nearly spherical. Although these assumptions, at present,... 

Platelet-leukocyte interactions and/or platelet-leukocyte microaggregates... 

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