title: A plasmin generation method for the determination of tissue plasminogen activator (t-PA) activity in blood.
abstract: A plasmin generation method to determine tissue plasminogen activator (t-PA) activity in plasma is described. A protein solution of homogenized fibrin was used as a stimulator in the presence of plasminogen and the plasmin generated was measured by the release of para-Nitroanilide (p-NA) from the chromogenic substrate S-2251. Plasmin generation by 5 iu/mL t-PA in the presence of 1 CU/mL of plasminogen and 850 micrograms/mL of fibrin solution reaches a peak at about 5 h incubation whilst in plasma, plasmin generation peaks after about 16 h incubation. The highest t-PA activity in plasma was determined using an assay involving 18 h incubation. In the 21 subjects studied by this method the t-PA activity at rest ranged from 0.34 to 0.92 iu/mL with a mean of 0.57 +/- 0.15 iu/mL of plasma whilst in the post-occlusion state the activity ranged from 1.12 to 18.0 iu/mL, with a mean of 5.25 +/- 4.49 iu/mL of plasma. We also found that subjects who developed petechiae during occlusion had significantly higher t-PA activity both at pre- and post-occlusion when compared with those who did not develop petechiae. The t-PA activity of acid-treated plasma stored at -70 degrees C showed no significant changes in activity after 12 weeks of storage when compared with the t-PA activity of the same plasma tested prior to storage.
authors.affiliation: National University of Singapore, Department of Obstetrics and Gynaecology, National University Hospital.
authors.forename: S C
authors.initials: SC
authors.lastname: Koh
authors.forename: R
authors.initials: R
authors.lastname: Yuen
authors.forename: O A
authors.initials: OA
authors.lastname: Viegas
authors.forename: S E
authors.initials: SE
authors.lastname: Chua
authors.forename: B L
authors.initials: BL
authors.lastname: Ng
authors.forename: D K
authors.initials: DK
authors.lastname: Sen
authors.forename: S S
authors.initials: SS
authors.lastname: Ratnam
mesh_terms: D000328:Adult; D004305:Dose-Response Relationship, Drug; D005260:Female; D005337:Fibrin / Q000494:pharmacology; D005341:Fibrinolysin / Q000096:biosynthesis / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D011693:Purpura / Q000201:enzymology; D010959:Tissue Plasminogen Activator / Q000097:blood* / Q000493:pharmacokinetics
chemical_list: D005337:Fibrin; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin