title: A chromogenic substrate assay kit for factor XII: evaluation and use for the measurement of factor XII levels in cardiopulmonary bypass patients.
abstract: Factor XII levels were determined in plasma samples from 75 patients before undergoing aortocoronary bypass grafting and from 40 healthy age-matched donors by using a microtitre plate adaptation of a new chromogenic peptide substrate assay kit for factor XII. The chromogenic peptide substrate assay values for factor XII correlated well with those obtained in clotting (r=0.90; y= 15.811+0.8236x) and immunochemical (r=0.88; y=17.90+0.817x) assays in the normal donor samples. Factor XII levels in the patients were significantly lower than those in the normal donors (83.3+/-23.2% versus 103.4+/-23.1: p=0.004), and nine patients (12%) had factor XII values below 50% compared with only one of the normal donors (2.5%). Factor XII levels and kallikrein-like activities (a measure of contact system activation) were followed before, during, and one day after cardiopulmonary bypass in 20 patients. Factor XII levels were significantly reduced, and kallikrein-like activities significantly elevated after 5 and 30 minutes cardiopulmonary bypass. One day after cardiopulmonary bypass both factor XII levels and kallikrein-like activities were significantly lower than preoperation values.
authors.affiliation: Kent Haemophilia Centre, Kent and Canterbury Hospital, United Kingdom.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gallimore
authors.forename: D W
authors.initials: DW
authors.lastname: Jones
authors.forename: H P
authors.initials: HP
authors.lastname: Wendel
mesh_terms: D000328:Adult; D000368:Aged; D002315:Cardiopulmonary Bypass; D002863:Chromogenic Compounds; D003327:Coronary Disease / Q000097:blood* / Q000601:surgery; D005069:Evaluation Studies as Topic; D005174:Factor XII / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
chemical_list: D002863:Chromogenic Compounds; D011933:Reagent Kits, Diagnostic; D005174:Factor XII