We have reported that prothrombin (1 microm) is able to replace high molecular weight kininogen (45 nm) as a cofactor for the specific binding of factor XI to the platelet (Baglia, F. A., and Walsh, P. N. (1998) Biochemistry 37, 2271-2281). We have also determined that prothrombin fragment 2 binds to the Apple 1 domain of factor XI at or near the site where high molecular weight kininogen binds...

Human platelets release platelet-derived growth factor (PDGF) from alpha-granules during platelet activation. We have previously shown that platelets have PDGF alpha-receptors, a transmembrane tyrosine kinase that takes part in negative feedback regulation during platelet activation. Here we have described a study of PDGF-induced tyrosine phosphorylation of platelet substrates and phosphoinosit...

The structure and function of the platelet surface was probed by phospholipase C (Clostridium perfringens) which hydrolyzes membrane phospholipids, particularly phosphatidylcholine. Platelet phospholipids were susceptible to phospholipase C, and extent of hydrolysis was dependent on concentration of phospholipase C and Ca(++). Phospholipase C (0.15 U/ml) with Ca(++) (0.55 mM) hydrolyzed 15.6% p...

Our ability to chemically characterize and synthesize this autacoid of allergy and inflammation has given us a unique opportunity to study these important molecules in a highly disciplined fashion. It has also opened the door to a vista of research approaches to define PAF's normal physiologic role as well as its actions as an immunopathologic mediator. Recent work is described.

This study was prompted by the observation that fresh platelet suspensions--prepared by gel filtration or albumin density gradient centrifugation--possessed only minimal factor V activity, whereas frozen-and-thawed platelet suspensions possessed striking factor V activity. Results of experiments with fresh suspensions suggested that unaltered platelets did not bind plasma factor V. The factor V...

Platelet-derived growth factor-stimulated actin rearrangement and edge ruffle formation have previously been shown to be dependent on activation of phosphatidylinositol 3'-kinase, the activity of which also is important for directed migration of cells. This lipid kinase binds to phosphorylated tyrosine residues Y740 and Y751 in the kinase insert of the human platelet-derived growth factor ss-re...

Propranolol, a non-selective beta blocker, was administered orally in therapeutic doses. The effects of a single dose (160 mg) and one week's treatment (80 mg twice a day) on platelet function were compared in healthy young subjects. There were no significant changes in circulating platelet aggregates, template bleeding time, platelet factor 3 availability and thromboxane beta 2 (TX beta 2) gen...

Background Platelets contain several factors that inhibit heparin. This study was designed to assess the heparinneutralizing activity present in acute, platelet-rich arterial thrombi formed at sites of arterial injury in animals. Methods and Results Platelet-rich thrombi (n=3) were induced in pig coronary arteries by balloon catheter-mediated arterial injury. Soluble extracts were prepared from...

BACKGROUND Clinical studies claim that platelet-rich plasma (PRP) shortens recovery times because of its high concentration of growth factors that may enhance the tissue repair process. Most of these studies obtained PRP using different separation systems, and few analyzed the content of the PRP used as treatment. PURPOSE This study characterized the composition of single-donor PRP produced b...