title: Factor XII fragment and kallikrein generation in plasma during incubation with biomaterials.
abstract: Blood biocompatibility of medical devices is in many ways dependent on surface characteristics and biochemical blood material interactions. In this study, the contact system, in which the activation of factor XII and plasma kallikrein is included, is highlighted. This article describes a simple chromogenic assay to determine the Hageman Factor fragment (HFf, or factor XIIf) and kallikrein activity in vitro. The assay is based on conversion of Z-Lys-Phe-Arg-pNA.2HCl to which human factor XIIf and kallikrein appeared to have a high affinity. To discriminate between the serine proteases factor XIIf and kallikrein to cleave this substrate, aprotinin was added to one of two complementary samples. In this in vitro study, standardized disks from glass, high-density polyethylene (HDPE), polytetrafluoro ethylene (PTFE), and polydimethyl siloxane (PDMS) were studied for their capacity to generate factor XIIf and kallikrein in plasma. Kaolin was used as positive control. On glass disks the highest and on HDPE the lowest generation of factor XIIf and kallikrein were found, both with a ratio of 1:1. On PDMS and on PTFE disks protease activities were intermediate, but with a factor XIIf and kallikrein activity ratio of 1:2 and 1:4, respectively. Apparently because of the hydrophobic surface character of PDMS and PTFE, these surfaces absorb or fail to produce the factor XIIf. This assay appeared to be discriminative even for materials that are considered mild activators of the contact system and can therefore be used as a standard method to qualify biomaterials.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: BioMedical Technology Center/Thorax Center, University Hospital Groningen, The Netherlands.
authors.forename: K W
authors.initials: KW
authors.lastname: van der Kamp
authors.forename: W
authors.initials: W
authors.lastname: van Oeveren
mesh_terms: D000595:Amino Acid Sequence; D007611:Aprotinin / Q000494:pharmacology; D001672:Biocompatible Materials / Q000737:chemistry*; D001777:Blood Coagulation; D002863:Chromogenic Compounds / Q000378:metabolism; D004789:Enzyme Activation; D005174:Factor XII / Q000378:metabolism*; D005342:Fibrinolysis; D005898:Glass / Q000737:chemistry; D006801:Humans; D007610:Kallikreins / Q000096:biosynthesis*; D008422:Materials Testing; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D010446:Peptide Fragments / Q000097:blood*; D011095:Polyethylenes / Q000737:chemistry; D011138:Polytetrafluoroethylene / Q000737:chemistry; D012826:Silicone Elastomers / Q000737:chemistry; D013379:Substrate Specificity; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D002863:Chromogenic Compounds; D009842:Oligopeptides; D010446:Peptide Fragments; D011095:Polyethylenes; D012826:Silicone Elastomers; C089221:benzyloxycarbonyl-lysyl-phenylalanyl-arginine-4-nitroanilide; D005174:Factor XII; D011138:Polytetrafluoroethylene; D007611:Aprotinin; D007610:Kallikreins