An evaluation of the euglobulin method for the determination of fibrinolysis.

Methods and Materials Reagents.-The reagents are 0.1 M ammonium oxalate in distilled water, and a borate solution made up of 9 g. sodium chloride and 1 g. sodium borate in 1,000 ml. distilled water. Streptokinase was purchased from Warszawska Wytw6rnia Surowic i Szczepionek. Fibrinogen was prepared by the method of Kekwick, Mackay, Nance, and Record (1955). Thrombin was prepared after separating prothrombin by the method of Lewis and Ferguson (1953) slightly modified. Prothrombin was converted to thrombin using the calcium-thromboplastin mixture, and thrombin was precipitated by acetone and extracted from the acetone-dried powder with distilled water. The euglobulin precipitation is based on an early observation of Milstone (1941) and Macfarlane and Biggs (1948) that plasminogen is a chief component of the euglobulin fraction. The method, as used here, has been worked out by Kowarzyk and Buluk (1950). Method-Blood was collected into 0.1 M ammonium oxalate in the proportion of 1 part of anticoagulant to 9 parts of blood, and plasma was obtained by centrifuging for 10 minutes at 1,500 r.p.m. To 0.5 ml. of plasma 8 ml. distilled water and 0.15 ml. 1% acetic acid were added. The pH should be approximately 5.2. After 30 minutes' incubation in a refrigerator at +4° C. the tubes were centrifuged for five minutes at 1,500 r.p.m. The supernatant was poured off and the tubes were drained by inverting on filter paper for about one minute. The precipitate