Critical Evaluation of the Fibrin Plate Method for Estimating Fibrinolytic Enzymes and Activators

Abstract

Summary1. Studies of the fibrinolytic effect of spontaneously activated plasmin preparations on normal and heated bovine fibrin plates showed that human plasmin preparations can be obtained, to which heated fibrin possesses a higher sensitivity than native fibrin.2. The results suggest that spontaneously activated human plasmin prepared from an euglobulin fraction is more or less accompanied by an agent which acts as activator for bovine plasminogen contained in native fibrin plates. It seems that this agent is identical to a serum factor which acts physiologically as plasminogen activator and is also responsible for the socalled “spontaneous activation”.3. The findings emphasize the necessity for standardizing testing procedures. Variations in processing the fibrinogen, variations in fibrinogen concentration, and especially in the duration of the heat treatment of the fibrin plates, may cause significant variations in the resulting sensitivity of the method which in turn may be reflected in diverging apparent activities.

On the Plasminogen Activator Forming Capacity of Human Plasma Globulins Reacting with Streptokinase

“…1 : 1 dilutions of these p rep aratio n s w ere tested for th eir lytic activities on healed an d native bovine fib rin plates. T h e lytic activities on b o th su b strates w ere expressed in units per mg pro tein according to A uersw ald and Doleschel (1). F o r the tests on norm al plates 1000 units of streptokinase w ere used per ml solution, for the tests on heated plates only 200 units of strep to k in ase per ml w ere applied.…”

Proteolytic enzymes in clinical medicine

“…Heating the plate (to allow measurement of plasmin in the absence of activator) also denatures the fibrin, making it more susceptible to digestion and therefore not comparable to the unheated plate. 3 The immunological methods which promise to be among the most specific are still only qualitative. gO Methods employing 131 1 labeled fibrinogen and fibrin 285 are probably the most suitable for investigative use at present, although they are cumbersome for routine clinical evaluation.…”

“…In 1959 attention was again focused on this problem by observations in two different laboratories. Tang and associates 329 were able to isolate and crystallize an enzyme from gastric juice which they called gastricsin and which is characterized by a pH optimum of 3. It was found to be homogeneous by ultracentrifugation and starch gel electrophoresis and differed from pepsin in its greater heat stability and its lower electrophoretic mobility.…”

On Fibrinolysis: A. In Pregnancy, Labour, Puerperium and During Treatment with Sex Hormones B. In Human Ontogenesis and in Human Organ Culture

“…Plasminogen contaminating fibrin can be destroyed by heating (Lassen 1952), but the fibrin is thereby partly denatured and less sensitive to plasmin (Auerswald & Doleschel 1960). Plasminogen is converted into plasmin by certain activators (see below).…”