title: Comparison of the spectrophotometric determination and the two-stage coagulation assay of tissue factor activity.
abstract: The tissue factor activity of human brain thromboplastin and 6 commercial thromboplastins was determined by a spectrophotometric method and a two-stage coagulation assay. The thromboplastins were incubated with an excess of Factor VII and Factor X, and the activation of Factor X was estimated from the rate of hydrolysis of the chromogenic substrate S-2222 and from the coagulation time of plasma enriched in phospholipids. The results obtained by the two methods were related linearly and showed a correlation coefficient of 0.89. The coefficient of variation was 11% in the spectrophotometric method and 25% in the two-stage coagulation assay.
mesh_terms: D001777:Blood Coagulation; D001921:Brain / Q000378:metabolism*; D005167:Factor VII / Q000008:administration & dosage; D005170:Factor X / Q000008:administration & dosage; D006801:Humans; D011516:Prothrombin / Q000378:metabolism; D011517:Prothrombin Time; D013053:Spectrophotometry; D013925:Thromboplastin / Q000134:cerebrospinal fluid*
chemical_list: D005167:Factor VII; D011516:Prothrombin; D005170:Factor X; D013925:Thromboplastin