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During blood-material interaction, the enzymes factor XII fragment (factor XIIf) and kallikrein are generated (contact activation). In this study, the enzymatic activities of factor XIIf and kallikrein were examined with an assay based on the conversion of tripeptide-p-nitroanilide substrate. With the use of aprotinin to inhibit kallikrein, the proteolytic activities of factor XIIf and kallikrein could be separately determined. In this in vitro study, two commercially available polyurethanes, Pellethane and Biomer®; three custom synthesized polyurethanes; a biomerlike 2000 Mw polytetramethyleneoxide containing polyurethane (PU-2000); an octadecyl extended (ODCE) biomer-like 2000 Mw Polytetramethyleneoxide containing polyurethane (PU-2000-ODCE); a hard-segment polyurethane (HS-PU); and glass (reference material) were incubated in 25% diluted plasma. In both series of experiments, glass caused the highest amidolytic activities by factor XIIf and kallikrein compared with any of the polyurethanes. In contrast, within the polyurethane group of materials, lower amidolytic activities by factor XIIf and kallikrein were measured on the custom-made polyurethanes than on the commercially available polyurethanes, although the differences among the polyurethanes were small. In addition, the influence of different ratios of material surface to the plasma incubation volume was studied. An increased ratio of surface area over plasma volume resulted in reduced contact activation, suggesting that plasma components are the limiting factor.

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 invitro. 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 asa standard method to qualify biomaterials. NOTE: Factor XIIf (mel wt. 28,000) is designated in the literature as HFf, beta-factor XIIa, or factor XII(LMW) and factor XIIa (mel wt. 80,000) as HFa; factor XIIa(HMW) or alpha-factor XIIa. To avoid the unfashionable use of beta-factor XIIa or alpha-factor XIIa, we chose in this study the use of factor XIIf and factor XIIa, according to the article by R. A. Pixley et al., Blood, 66, 198-300 (1985). (C) 1994 John Wiley and Sons, Inc.

Ninety seven Cannabis accessions were evaluated for cannabinoid content and non-chemical plant characters. Variation within populations for cannabinoid content, and consistency of chemical characters at the population level were investigated. The relationship between chemical and other plant characters was very limited. Leaflet width and phenological data can be used for a rough prediction of the chemical phenotype on a population level. Various combinations of cannabinoid content and other economic plant characters were observed, thus a breeding programme will not be hampered by strict linkage. For a selection programme a direct analysis of cannabinoids will be inevitable.

The surface of our extracorporeal circuit (from Bentley/Baxter company) that contained a hollow-fiber oxygenator was treated with heparin, a so-called Duraflo II-heparin treatment. All components of the circuit were treated with heparin except for the cardiotomy reservoir which could not be treated with heparin. Thirty patients participated in the study: 15 patients were perfused with a heparin-treated extracorporeal circuit, and 15 other patients were perfused with an identical circuit, but without heparin-treatment of the surface. All patients were also systemically heparinized in a standard way; this meant a starting dose of 3 mg/kg and an additional dose of 1 mg/kg after 1 h of perfusion.

Glucosinolates (GSL) belong to non-nutritional natural compounds and occur in Crucifers. Rapeseed containing high amounts of GSL, 100 micromol per gram seed, is fed to cattle. The European Community stimulates the cultivation of double zero rapeseed with GSL content below 20 micromol/g seed.