[Role of staphylococcus aureus hemolytic toxin-alpha in pathogenesis of infectious endocarditis: studies in vitro].

Aim: To study effects of alpha-toxin (AT) Staphylococcus aureus on human platelets and endothelial cells.

Materials And Methods: Concentrations of intracellular calcium in human platelets and endothelial cells were estimated by fluorescence, phosphoinositide metabolism in the endothelial cells was studied using 3H-myoinositole.

Results: AT induced a dose-dependent increase of intracellular calcium in blood and vascular cells, stimulates dose-dependent formation of inositol phosphates in endothelial cells.

[Interaction of the beta1-subunit of G-proteins with the actin cytoskeleton].

Using immunoblotting with specific antibodies, we have identified beta 1- and beta 2-subunits of Gi-proteins in membrane and cytosolic fractions of pig lung. It has been shown that beta 1-subunit is present both in membrane and cytosolic fractions, whereas beta 2-subunit is associated only with membranes. Activation of membrane-bound G proteins with non-hydrolysable GTP analogues have led to partial release from membrane of beta 1-, but not beta 2-subunits.