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Protein, Cellular and Soft Tissue Interactions with Polyurethanes
Published in Nina M. K. Lamba, Kimberly A. Woodhouse, Stuart L. Cooper, Polyurethanes in Biomedical Applications, 2017
Nina M. K. Lamba, Kimberly A. Woodhouse, Stuart L. Cooper
Attempts to circumvent the thrombogenicity of artificial surfaces have involved the grafting of heparin, a naturally occurring anticoagulant, on to polymer surfaces. Heparin catalyses the neutralization of thrombin and FXa by antithrombin III (AT III). Polyurethanes have been heparinized,85,86 and other molecules such as PEO and albumin have been incorporated as spacer arms, to enhance the effect of the heparin.87–89In vitro studies of these materials have shown reduced protein deposition and platelet adhesion, and increased occlusion times ex vivo. Thrombomodulin, a protein sythesized by the vascular endothelium that inhibits coagulation, also has been used to moderate the action of thrombin.90 Sulfonated polyurethanes have been shown to possess anticoagulant properties.69 The presence of alkyl chains on the surface can alter the protein adsorption profile, favoring the adsorption of albumin, and thus reduce the thrombogenicity of polyurethane surfaces.45
Purification and characterization of Protein C activator from Agkistrodon acutus Venom
Published in Preparative Biochemistry & Biotechnology, 2020
Yao Sun, Peng-Ju Bao, Gen-Bao Zhang
Protein C (PC) is a vitamin K-dependent protein that circulates in the blood.[1] The protein C zymogen is activated upon binding to thrombin,[2] and its activation is induced by the presence of thrombomodulin (TM) and endothelial protein C receptors (EPCR).[3] PC is hydrolyzed from a peptide chain to become activated protein C (APC). APC plays important roles in the regulation of blood clotting,[4] inflammation,[5] cell death, and blood vessel wall permeability in humans and other animals[6] by proteolytically inactivating factors Va and VIIIa. Because of the crucial role of protein C as an anticoagulant, individuals with deficiencies in protein C or resistance to APC[7] are at increased risk of developing life-threatening blood clots. A decrease in the PC level generally associates with a decrease in PC activity. However, in some cases, the level of PC is normal but the activity of PC has been reduced by half.[8] Therefore, the detection of PC activity is more diagnostically significant for patients with cardiovascular diseases. Presently, the key methods to detect PC activity[9] are the chromogenic assay and APTT test.[10] In a previous study, it was reported that snake venom contains an enzyme that activates plasma PC independent of thrombomodulin–endothelial protein C receptor (TM/EPCR).[11] This protein has been designated as protein C activator (PCA). Other studies have demonstrated that PCA is mainly present in Agkistrodon halys halys snake venom.[12] PCA has a molecular mass of approximately 37 kD[13] and is a valuable commodity named PROTAC,[14] which is isolated from Agkistrodon contortrix contortrix venom (ACCV). However, the use of the chromogenic assay is limited because of the high price of PROTAC.