Fibrinolytic Activity of Thrombin Preparations

Abstract

SummarySome thrombin samples have a slight unspecific protease activity probably caused by contaminating plasmin. All investigated samples were fibrinolytically active. This activity was caused by an activator of plasminogen. Fibrinolytic activity was apparently produced by two components of the thrombin preparations. One of these components was a contaminant with fibrinolytic activity but with no thrombin activity. This component could be separated from the thrombin by simple chemical procedures. The other fibrinolytic component appeared to be the thrombin molecule per se. It was not fibrinolytically active when used in the low concentrations required for clotting of fibrinogen, but in high concentrations, assayed on the fibrin plate, it activated plasminogen. In the accurate assay of fibrinolytic agents it is necessary to use preparations of thrombin from which the contaminating fibrinolytic agent has been removed.

Activation of Chymotrypsinogen-A by Thrombin Preparations*

“…Of paramount importance is the question whether chymotrypsinogen was activated by the thrombin, or by contaminants of trypsin, of trypsinlike enzymes, of other proteases or arginyl esterases, all of which have been described in blood (Gullick, 1963;Hudemann, 1940;Brakman et al, 1964;Mehl et al, 1964;Floch and Groisser, 1960), as well as in commercial and partially purified thrombin preparations (Hudemann, 1940;Brakman et al, 1964). Every effort has been made to resolve this question by the use of appropriate differentiating inhibitors and experimental conditions.…”

Función de la protombina y derivados protombínicos en la coagulación sanguínea. II

“…Para obvia r este inconven iente se buscó un activador de la protrombina, que generand o auto-Ca ++ Cefalina T rombina-AcG de aquella, teniendo, por ejemplo, simila r peso molecular 117 e iguales constantes de sedimentación 90 • Dicha si milit ud viene corroborad a por el hecho experimental de que la autoprotrom bin a III se puede transformar en autoprotrombina e incubándola con citrato sódico al 25 % 52 , generándose por este camino la misma cantidad d e autoprotrombi na e que se obtendría si desde un principio el proceso se hubiera llevado a cabo por su vía de activación habitual. T odo lo a nterior hace suponer que la autoprotrombina llT constituye un estado inactivo previo , una especie de precursor, de la autoprotrom bina e 5t92 [11].…”

Intracranial Surgery in Hemophiliacs

“…They may be antibodies acting against a protein such as factor VIII, which is foreign to the hemophiliac, or they may be en¬ zymes, present initially in small amounts or in an inactive form, which increase in con¬ centration or become active when their sub¬ strate increases in amount. 65 Theoretically, the presence of inhibitors cotraindicates surgical intervention since they neutralize the effect of infusions of factor VIII and bleeding cannot be controlled. Attempts to overcome an inhibitor by massive infusion of concentrated factor VIII, by exchange transfusion and by immunosuppressive therapy have not been successful in the past.66"68…”