Broadly neutralizing epitopes in the Plasmodium vivax vaccine candidate Duffy Binding Protein

Plasmodium vivax Duffy Binding Protein (PvDBP) is the most promising vaccine candidate for P. vivax malaria. The polymorphic nature of PvDBP induces strain-specific immune responses, however, and the epitopes of broadly neutralizing antibodies are unknown. These features hamper the rational design of potent DBP-based vaccines and necessitate the identification of globally conserved epitopes. Using X-ray crystallography, small-angle X-ray scattering, hydrogen-deuterium exchange mass spectrometry, and mutational mapping, we have defined epitopes for three inhibitory mAbs (mAbs 2D10, 2H2, and 2C6) and one noninhibitory mAb (3D10) that engage DBP. These studies expand the currently known inhibitory epitope repertoire by establishing protective motifs in subdomain three outside the receptor-binding and dimerization residues of DBP, and introduce globally conserved protective targets. All of the epitopes are highly conserved among DBP alleles. The identification of broadly conserved epitopes of inhibitory antibodies provides critical motifs that should be retained in the next generation of potent vaccines for P. vivax malaria.

Allosteric activation of ADAMTS13 by von Willebrand factor

The metalloprotease ADAMTS13 cleaves von Willebrand factor (VWF) within endovascular platelet aggregates, and ADAMTS13 deficiency causes fatal microvascular thrombosis. The proximal metalloprotease (M), disintegrin-like (D), thrombospondin-1 (T), Cys-rich (C), and spacer (S) domains of ADAMTS13 recognize a cryptic site in VWF that is exposed by tensile force. Another seven T and two complement C1r/C1s, sea urchin epidermal growth factor, and bone morphogenetic protein (CUB) domains of uncertain function are C-terminal to the MDTCS domains. We find that the distal T8-CUB2 domains markedly inhibit substrate cleavage, and binding of VWF or monoclonal antibodies to distal ADAMTS13 domains relieves this autoinhibition. Small angle X-ray scattering data indicate that distal T-CUB domains interact with proximal MDTCS domains. Thus, ADAMTS13 is regulated by substrate-induced allosteric activation, which may optimize VWF cleavage under fluid shear stress in vivo. Distal domains of other ADAMTS proteases may have similar allosteric properties.

Retrobulbar block using pentothal as a sedative for ambulatory cataract surgery

Cataract surgery comprises 80% to 85% of the surgical procedures performed at our ambulatory surgical center. We have developed a safe and effective method of sedation and amnesia for performing a retrobulbar block. We use sodium thiopental, administered intravenously, just prior to the block. We encourage the anesthesia departments of other facilities to consider this relatively simple blocking procedure for the comfort and safety of the patient.