Background: Increased platelet reactivity has been implicated in cardiovascular disease the major cause of death in patients with end stage renal disease (ESRD). FcGammaRIIA is a component of glycoprotein VI and Ib-IX-V that mediate activation of platelets by collagen and von Willebrand factor. To determine whether expression of FcGammaRIIA impacts platelet reactivity we quantified its expression and platelet reactivity in 33 patients with ESRD who were undergoing hemodialysis. Methods: Blood samples were obtained from patients immediately before hemodialysis and before administration of heparin. Platelet expression of FcGammaRIIA and the activation of platelets in response to low concentrations of convulxin (1 ng/ml, selected to mimic effects of collagen), thrombin (1 nM), adenosine diphosphate (ADP, 0.2 uM), or platelet activating factor (PAF, 1 nM) were determined with the use of flow cytometry in samples of whole blood anticoagulated with corn trypsin inhibitor (a specific inhibitor of Factor XIIa). Results: Patients were stratified with respect to the median expression of FcGammaRIIA. Patients with high platelet expression of FcGammaRIIA exhibited 3-fold greater platelet reactivity compared with that in those with low expression in response to convulxin (p < 0.01) and 2-fold greater activation in response to thrombin, ADP, and PAF (p < 0.05 for each). For each agonist, expression of FcGammaRIIA correlated modestly but positively with platelet reactivity. The strongest correlation was with thrombin-induced activation (r = 0.6, p < 0.001). Conclusion: Increased platelet reactivity in response to low concentrations of diverse agonists is associated with high expression of FcGammaRIIA and may contribute to an increased risk of thrombosis in patients with ESRD.

Judge Bans Logging in Owl Habitat
A federal judge issued a preliminary injunction Wednesday to stop Weyerhaeuser Co. from logging in spotted owl habitat on four parcels of private land in Washington. U.S. District Judge Marsha J. Pechman did not grant, however, an additional request by the Seattle Audubon Society to stop the state of Washington from granting permits to log in spotted owl habitat. The injunction from logging covers spotted owl habitat within 2.7 miles of the center of four circles of land in southwestern Washington that are owned by Weyerhaeuser. “It really shows the Endangered Species Act still has some teeth in it,” said Kenan Block, a spokesman for the Washington Forest Law Center. Weyerhaeuser spokesman Frank Mendizabal said the company was disappointed in some aspects of Pechman’s ruling but did not think the injunction would affect its operations in the short term because Weyerhaeuser is not currently logging in the 50,000 acres in question. He said Weyerhaeuser has been working with the U.S. Fish and Wildlife Service to study and protect spotted owls and will continue to manage the land in a way it feels is consistent with the judge’s order. “We’re confident that Washington state and Weyerhaeuser will prevail when the matter is decided” at trial sometime next year, Mendizabal said. The owl was declared a threatened species in 1990 under the federal Endangered Species Act primarily because of heavy logging in the old growth forests where it nests and feeds. While old growth forests suitable for owl habitat have increased, owl numbers have continued to decline. The spotted owl also faces a new threat from a cousin, the barred owl, that has been invading its territory.

July 26th, 2007: Cartoon #4237
‘Your parents aren’t outsourcing, I’m the babysitter.’ For Your health: Nutritional Support for healthy Nerves Your nervous system is responsible for sending, receiving and processing nerve impulses throughout your body. Optimal nerve function is important to many areas of health, including cardiovascular, muscle and joint, respiratory, vision and […]

Platelet adhesion onto immobilized fibrinogen under arterial and venous in-vitro flow conditions does not significantly differ between men and women
Background: Gender-related differences in incidence of arterial thrombosis have been a focus of interest for years. The platelet integrin IIb 3 is primarily responsible for the interaction between platelets and fibrinogen and consecutive thrombus growth. In this study, we evaluated platelet adhesion onto immobilized fibrinogen under venous and arterial flow conditions in men and women. Methods: Platelets in whole anticoagulated blood were labelled with the fluorescence dye Mepacrine and perfused through the rectangular flow chamber over glass cover slips coated with fibrinogen (shear rates of 50 s-1, 500 s-1 and 1500 s-1). A fluorescence laser-scan microscope was used for visualisation and quantification of platelet adhesion at 15 seconds, 1 and 5 minutes after the start of perfusion. Results: During perfusion, the platelet adhesion linearly increased in regard to exposition time and shear rate. After five minutes of perfusion the platelet adhesion onto immobilized fibrinogen showed no significant gender related difference, neither at 50 s-1 nor at 500 s-1 and 1500 s-1 (p > 0.05), respectively. No significant difference in platelet adhesion onto immobilized fibrinogen, in regard to the menopausal status, was either observed (p > 0.05). Conclusion: In our in vitro experimental system, hormonal differences between men and women did not influence platelet adhesion onto immobilized fibrinogen, neither under venous nor under arterial rheological conditions.

This entry was posted on Thursday, August 2nd, 2007 at 4:28 pm and is filed under Medical. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.