Safety and Efficacy of Single-Dose Ad26.COV2.S Vaccine against Covid-19.

Background: The Ad26.COV2.S vaccine is a recombinant, replication-incompetent human adenovirus type 26 vector encoding full-length severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein in a prefusion-stabilized conformation.

A Reliable von Willebrand factor: ristocetin cofactor enzyme-linked immunosorbent assay to differentiate between type 1 and type 2 von Willebrand disease.

von Willebrand disease (vWD) is the most common hereditary bleeding disorder due to either a qualitative or a quantitative defect in von Willebrand factor (vWF). vWF is a multimeric plasma protein that plays an important role in (1) primary hemostasis, by sustaining indirect platelet adhesion especially at high shear rates, and in (2) secondary hemostasis, by protecting factor VIIIc (FVIIIc) from degradation. A correct diagnosis of vWD is based on the accurate identification of one of the six different subtypes (type 1, 2A, 2B, 2M, 2N, 3).

Inhibition of the von Willebrand (VWF)-collagen interaction by an antihuman VWF monoclonal antibody results in abolition of in vivo arterial platelet thrombus formation in baboons.

The interaction between collagen, von Willebrand factor (VWF), and glycoprotein Ib is the first step in hemostasis and thrombosis especially under high shear conditions. We studied the inhibition of the VWF-collagen interaction by using an antihuman VWF monoclonal antibody 82D6A3 to prevent arterial thrombosis in baboons to develop a new kind of antithrombotic strategy and determine for the first time experimental in vivo data concerning the importance of the collagen-VWF interaction. We used a modified Folts model to study the antithrombotic efficacy of 82D6A3, where cyclic flow reductions (CFRs) were measured in the femoral artery.

Inhibition of platelet glycoprotein Ib, glycoprotein IIb/IIIa, or both by monoclonal antibodies prevents arterial thrombosis in baboons.

The antithrombotic efficacy of the monoclonal antibodies 6B4-Fab and MA-16N7C2 against platelet glycoprotein (GP) Ib and GP IIb/IIIa, respectively, on acute platelet-mediated thrombosis was evaluated in a baboon model of femoral artery stenosis, which is a modification of the original Folts model: platelet thrombi form on the injured stenosed artery, producing cyclic flow reductions (CFRs). A dose of 0.6 mg/kg 6B4-Fab significantly reduced the CFRs by 59 +/- 15%, whereas 2 mg/kg 6B4-Fab completely abolished the CFRs without prolongation of the bleeding time.