Platelet activation morphology

Thrombin and other agents cause platelet aggregation, which involves a variety of biochemical and morphologic events. Stimulation of phosphofipase C and the polyphosphoinositide pathway is a key event in platelet activation, but other processes are also involved. 

Zeck Kapp, G., Kroegel, C., Riede, U. N., and Kapp, A. (1995) Mechanisms of human eosinophil activation by complement protein C5a and platelet-activating factor similar functional responses are accompanied by different morphologic alterations. Allergy 50, 34 47. 

When platelets were mica-activated they exhibited a dramatic changes of cell shape (Fig. 2a). The most striking features of the mica-activated platelets surface morphology were the formation of two different actin-based structures, filopodia and lamellipodia, and the increase in area of platelet surface. Platelets in the initial stages of adhesion to mica produced several long filopodia with width of 180-300 nm and height of 60-90 nm extending over the substrate. As the adhesion process advanced, the filopodia expanded laterally over the... 

Platelets are important in homeostasis. Platelet activity is assessed by quantifying the number and morphology of platelets in a blood sample and by assessing platelet aggregation and specific platelet functions. Platelet function can also be assessed by performing a bleeding time (Handin, 1998). 

In rabbits, supplementing saturated fat diet with olive oil improved lipid profile, reduced vascular thrombogenecity and platelet activation with less severe morphological lesions of the endothelium and the vascular wall (97). 

The bulk stmcture of the catalyticaHy active phase is not completely known and is under debate in the Hterature (125,131—133). The central point of controversy is whether (Valone or in combination with other phases is the most catalyticaHy active for the conversion of butane to maleic anhydride. The heart of this issue concerns the role of stmctural disorder in the bulk and how it arises in the catalyst (125,134,135). Most researchers agree that the catalysts with the highest activity and selectivity ate composed mainly of (Vthat exhibits a clustered or distorted platelet morphology (125). It is also generaHy acknowledged that during operation of the catalyst, the bulk oxidation state of the vanadium in the catalyst remains very close to the +4 valence state (125). 

Antipyretic activity. Ethanol (50%) extract of the plant, administered intraperito-neally to guinea pigs, was inactive " . Anti-thrombotic effect. Olive oil extract of the fmit, administered intragastrically to male rabbits at a dose of 150 g/kg, was active. Lipid profile was improved with decreased platelet hyperactivity and subendot-helial thrombogenicity and less severe morphological lesion of the endothelium and vascular wall . 

Figure 12.10 Bright-field transmission electron micrographs of platelet morphologies in (a) VPO-0.1, (b) VPO-8, (c) VPO-84 and (d) VPO-132 activated catalysts [94]. (Reproduced with permission).

Hensler ME, Frojmovic MM, Taylor RG, Hantgan RR, and Lewis JC. Platelet morphological changes and fibrinogen receptor localization initial responses in ADP-activated human jdatelets. Am J Pathol 1992 141 707-719. 

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