Earlier studies have shown that isolated platelets in buffer systems can promote activation of FXII or amplify contact activation. in the presence of it negatively charge Substance or material Still proof is lacking that FXII is activated by platelets in a more physiological environment In this study we investigate if activated platelets can induce FXII-mediated contact activation and whether this activation affects clot formation in human blood.

Human platelets were activated with a thrombin receptor-activating peptide, SFLLRN-amide, in platelet-rich plasma or in whole blood. FXIIa and FXIa in complex with preferentially antithrombin (AT) and to some extent C1-inhibitor (C1INH) were generated in response to TRAP stimulation. This contact activation was independent of surface-mediated contact activation, tissue factor pathway or thiombin. In clotting whole blood FXIIa-AT and FXIa-AT complexes were specifically formed. demonstrating that AT is a potent inhibitor of FXIIa and FXIa generated by platelet activation Contact activation proteins were analyzed by flow cytometry and FXII, FXI, high-molecular weight kininogen, and prekallikrein were detected oil activated platelets Using chromogenic assays, enzymatic activity of platelet-associated FXIIa, FXIa, and kallikrein were demonstrated Inhibition of FXIIa in non-anticoagulated blood also prolonged the clotting time.

We conclude that platelet activation triggers FXII-mediated contact activation oil the Surface and in the vicinity of activated platelets This leads specifically to generation of FXIIa-AT and FXIa-AT complexes, and contributes to clot formation Activated platelets may thereby constitute an intravascular locus for contact activation, which may explain the recently reported importance of FXII in thrombus formation (C) 2009 Published by Elsevier Inc.

Warfarin is an important oral anticoagulant drug that demonstrates a molecular-environment dependent structural diversity. Previous investigations of warfarin’s ensemble of isomers in organic solvent-based environments have pointed to the importance of the closed-ring cyclic hemiketal form of the drug in non-polar environments, e.g. the interior of proteins, enzymes and biomembranes. Detection of the presence of these isomers in polar environments has not yet been reported. Here, we demonstrate the presence of the cyclic hemiketal structural form of warfarin under aqueous conditions. This finding underscores the importance considering all structural isomers of this drug when making predictions on warfarin’s bioavailability.

Here we report on a novel method for the direct in situ measurement of specific isomeric forms of the anticoagulant warfarin using time correlated single-photon counting (TCSPC) spectroscopy in conjunction with synthetic Sudlow I binding site receptors. The method is highly robust over the clinically significant concentration range, and demonstrates the potential of the binding site mimics in conjunction with the spectroscopic strategy employed here for the determination of this important pharmaceutical in clinical or even environmental samples.

In Saccharomyces cerevisiae, Pho89 mediates a cation-dependent transport of P_i across the plasma membrane. This integral membrane protein belongs to the Inorganic Phosphate Transporter (PiT) family, a group that includes the mammalian Na⁺/P_i cotransporters Pit1 and Pit2. Here we report that the Pichia pastoris expressed recombinant Pho89 was purified in the presence of Foscholine-12 and functionally reconstituted into proteoliposomes with a similar substrate specificity as observed in an intact cell system. The alpha-helical content of the Pho89 protein was estimated to 44%. EPR analysis showed that purified Pho89 protein undergoes conformational change upon addition of substrate. 

Inflammation is centrally involved in the development of cardiac hypertrophy and the processes of remodelling. The complement system and Toll-like receptor (TLR) family, two upstream arms of the innate immune system, have previously been reported to be involved in cardiac remodelling. However, the role of complement component 3 (C3), TLR co-receptor CD14 and the synergy between them have not been addressed during pressure overload-induced cardiac remodelling. Here, we examined angiotensin II-induced cardiac hypertrophy and remodelling for 7 days in male C57Bl/6 J mice deficient in C3, CD14, or both (C3CD14), and WT controls. Angiotensin II infusion induced a mild concentric hypertrophic phenotype in WT mice with increased left ventricle weight, wall thicknesses and reduced ventricular internal diameter, associated with increased cardiac fibrosis. However, there were no differences between WT mice and mice deficient for C3, CD14 or C3CD14, as systolic blood pressure, cardiac function and structure and levels of fibrosis were comparable between WT mice and the three other genotypes. C5a did not change in angiotensin II treated mice, whereas Mac2 levels were increased in angiotensin II treated mice, but did not differ between genotypes. The inflammatory IL-6 response was comparable between WT and C3 deficient mice, however, it was decreased in CD14 and C3CD14 deficient mice. We conclude that deficiency in C3, CD14 or C3CD14 had no effect on cardiac remodelling following angiotensin II-induced pressure overload. This suggests that C3 and CD14 are not involved in angiotensin II-induced adverse cardiac remodelling. (C) 2020 Published by Elsevier Inc.