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A B S T R A C T The platelets from three patients withBernard-Soulier syndrome have been analyzed by surface-labeling coupled with two-dimensional gel electrophoresis and compared with normals. As well as the previously described absence or deficiency in glycoprotein (GP) Ib(a) it could be shown that GP Ib,3 and an additional low molecular weight glycoprotein GP75.8-65 were not detectable using carbohydrate-labeling methods or deficient to the same extent as the GPIba subunit. In addition, the thrombin cleavable glycoprotein could not be detected using carbohydrate-labeling methods in two patients and was deficient in a third. This finding was confirmed in a fourth patient by one-dimensional gel electrophoresis. Thus, the changes in the membrane of Bernard-Soulier platelets are more complex than previously thought.

Background and Purpose-Although new, large, double-blind, randomized studies are needed to establish the efficiency of intravenous thrombolysis, open trials of sufficient size may also provide novel data concerning specific outcomes after thrombolysis. Methods-An open study of intravenous rtPA in 100 patients with internal carotid artery (ICA) territory strokes between 20 and 81 years of age, with a baseline Scandinavian Stroke Scale (SSS) score of Ͻ48 at entry was conducted. Inclusion time was within 7 hours after stroke onset. rtPA (0.8 mg/kg) was infused for 90 minutes, with an initial 10% bolus. Heparin was given according to 3 consecutive protocols. The SSS evaluation was done on days 0, 1, 7, 30, and 90. CT scan was performed before treatment, on days 1 and 7. Etiological investigations included echocardiography and carotid Doppler sonography and/or angiography. Outcome at 1 year was documented by SSS score, the modified Rankin Scale (mRS) score, and a 10-point invalidity scale. Multivariate logistic regression was used to identify predictors of poor versus good outcome. Results-At day 90, 45 patients (45%) had a good result, defined as complete regression or slight neurological sequelae (mRS score of 0 -1), 18 patients had a moderate outcome (mRS 2-3), and 31 patients had serious neurological sequelae (mRS 4 -5). Six patients died, 2 with intracerebral hematoma after immediate heparin. Five of 11 patients (45.5%) treated between 6 and 7 hours had a good result. The overall intracerebral hematoma rate was 7%. Higher values of fibrin degradation products at 2 hours were observed in the subgroup with intracerebral hematomas. Significant predictors of poor outcome on multivariate logistic regression analysis were baseline SSS score of Ͻ15 (odds ratio [OR], 3.38; 95% confidence interval [CI], 1.07 to 10.74; Pϭ0.04), indistinction between white and gray matter on CT scan (OR, 6.59; 95% CI, 2.19 to 19.79; Pϭ0.0008), and proximal internal carotid thrombosis (OR, 3.29; 95% CI, 0.99 to 10.95; Pϭ0.05). Conclusions-Our study confirms the safety of intravenous rtPA at a dose of 0.8 mg/kg and suggests efficacy for this drug even within 7 hours. Outcome and hematoma rates were at least as favorable as for trials of therapy with a 3-hour time window. Subgroups with a poor prognosis include low baseline neurological score, baseline CT changes, and proximal ICA thrombosis. However, approximately 30% of patients with each of these characteristics show a good outcome, so their inclusion in future routine rtPA protocols is still justified. (Stroke. 1998;29:2529 -2540.)

Background-Little is known about the coagulation factors as predictors of cerebral bleeding in rt-PA thrombolysis. The aim of this study was to determine what early coagulation parameters could predict early hemorrhagic lesions. Methods-Consecutive patients were included in the Lyon rt-PA protocol. Early hematomas (within 24 hours), diagnosed on an anatomoradiological basis (symptomatic and not symptomatic) were considered for the study. Fibrinogen and fibrin(ogen) degradation products (FDP) were assessed at entry and at 2 and 24 hours after the beginning of thrombolysis.

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The specificy of five monoclonal antibodies (P1 -P6) against platelet surface components was determined by immunoprecipitation of surface-labelled platelets from normal donors and patients with known platelet glycoprotein defects, followed by analysis by gel electrophoresis. Three (P2, P4 and P6) precipitated glycoproteins IIb and IIIa and, in addition, P2 precipitated glycoprotein la. PI precipitated normally only glycoprotein Ib also Ia when the platelets were pretreated with neuraminidase. P3 precipitated principally glycoprotein Ia but glycoprotein Ib was also weakly precipitated. The effects of the monoclonals on platelet function were tested. P1 and P2 completely inhibited and P3 slightly inhibited thrombin-induced platelet aggregation. P2 also inhibited collagen-induced aggregation and partially inhibited ADP-induced platelet aggregation. P3, P4 and P6 partially inhibited ADP-induced platelet aggregation. None had any effect on ristocetin-induced aggregation despite Pl and P3 binding to glycoprotein Ib. These results confirm the role of glycoproteins IIb and lIIa in aggregation induced by various agents and suggest that the function of glycoprotein Ib in thrombin-induced aggregation is more important than previously suspected and that glycoprotein la may also be involved in platelet functions.

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Human thrombospondin, a 450-kDa glycoprotein isolated from platelets and endothelial cells, specifically interacts with osteonectin, a protein of 30 kDa isolated from bovine bones and human platelets. Using ELISA, purified osteonectin binds to solid-phase-adsorbed thrombospondin with a dissociation constant (&) of 0.7 nM. Binding of thrombospondin to solid-phase-adsorbed osteonectin was also observed (& = 0.86 nM). The interaction of thrombospondin with solid-phase-adsorbed osteonectin was significantly decreased (81 % inhibition) when using an excess of fluid-phase osteonectin. Thrombospondin-osteonectin complex formation was calciumdependent as shown by a 50 -80% inhibition in the presence of EDTA. None of the proteins known to interact with thrombospondin (fibrinogen, fibronectin, collagen, plasminogen) had a significant inhibitory effect on thrombospondin-osteonectin complex formation. This selective interaction was confirmed by affinity chromatography. Iodinated osteonectin, previously incubated with purified thrombospondin, specifically bound to an anti-thrombospondin monoclonal antibody (P10) linked to protein-A -Sepharose 4B. Elution of the antithrombospondin antibody from protein A allowed the recovery of the thrombospondin-osteonectin complex in the eluate, as judged by SDS/polyacrylamide gel electrophoresis and autoradiography. Blotting of purified thrombospondin to osteonectin adsorbed onto nitrocellulose further confirmed complex formation. In addition, when released from thrombin-stimulated platelets, thrombospondin and osteonectin bound to anti-thrombospondin IgG-coated plates indicating that osteonectin was complexed to thrombospondin once the platelet-release reaction has occurred.Thrombospondin is a platelet a-granule glycoprotein which is secreted in response to thrombin [l]. This glycoprotein has a molecular mass of 450 kDa and is composed of three equivalent disulphide-linked chains of 150 -160 kDa [2]. Each thrombospondin chain is made up of several protease-resistant domains, which bind specifically with heparin, fibrinogen, fibronectin, collagen, calcium, histidine-rich glycoprotein and plasminogen (for review see [3]).Thrombospondin is synthesized by a wide range of cultured cells [3 -71 including fibroblasts, monocytes, macrophages, endothelial and smooth muscle cells [3] and is incorporated into their extracellular matrices [8,9]. Source-specific differences in fragmentation patterns between thrombospondin molecules were reported following exposure to proteolytic enzymes [lo -121, suggesting thrombospondin polymorphism [ll].The exact physiological function(s) of thrombospondin is unknown; however, there is growing evidence that it takes part in the platelet aggregation process [13, 141 and promotes cell adhesion [6, 71. Recently human platelets have been shown to contain and secrete a 30-kDa phosphoprotein [15], namely osteonectin, which is a major protein of mineralized bone [16, 171. Platelet osteonectin is identical to bovine bone osteonectin in terms of molecular mass and immuno...