Technical Remarks on the Microscopical Demonstration of Tissue Plasminogen Activator

Abstract

SummaryThe authors examine some variables capable of influencing the results obtained with the fibrin slide technique for microscopical demonstration of fibrinolytic activators in tissues (Todd’s method).The speed of freezing of the tissue specimen proved to be especially important. Slow freezing of the specimen should be avoided since it results in sections of poor quality and may alter the distribution of fibrinolytic activity. The optimal thickness of the sections lies between 6 and 8 (jim. The concentration of fibrinogen used as substrate may vary between 0.7 and 2.0% and the thickness of the fibrin film between 0.07 and 0.21 mm. Increasing the temperature of incubation from +4° C to +37° C enhanced fibrinolysis, but had no effect on the distribution of fibrinolytic activity in the sections. Storage of the sections at —20° C and at +4° C for 6 days had no apparent effect on their fibrinolytic activity. Storage at 28° C resulted in a considerable loss of the fibrinolytic activity of the sections. The error of a method to assess the strength of fibrinolytic activity of the section is determined.

Distribution and Variation of Fibrinolytic Activity in the Walls of Human Arteries and Veins

“…The small blood vessels were studied in specimens o f different organs and tissues, while the medium-sized and large vessels were obtained without adjacent tissues. Since rapid freezing is important [25], all specimens were immediately frozen in isopen tane, cooled with liquid nitrogen or dry ice, and then stored at -20 C in air-tight jars.…”

Development of Glomerular Fibrinolytic Activity in the Rat

“…This dose was selected for the further study. In the present method the GFA was due to the plas minogen activator and not to unspecific processes, as heat ing of the fibrin film to 85 C, to destroy plasminogen, resulted in complete inhibition of fibrinolysis [16].…”

“…The aim of this study was to compare the GFA in rats 2 weeks of age with the GFA in rats 2 months of age. The GFA was measured in normal rats and in rats after the injection of liquoid using the fibrin-slide method [16]. A single injection of liquoid, a synthetic acid polymer (sodium polyanethol sul fonate), produces the generalized Shwartzman reaction both in rabbits and rat with great consistency [4], A series of complicated reactions are initiated of which direct or indirect activation of Hageman factor and probably endo thelial injury are essential to produce a full-blown general ized Shwartzman reaction [4].…”

A New Method for the Detection of the Plasminogen Activator Content of Vein Walls

“…The vein samples are taken from specimens removed at operation and stored in Michaelis buffer solution at 4 °C until tested -usually within 24 h although storage of samples at this temperature has been shown not to affect fibrinolytic activity for a week as estimated by Pandolfi et al's [6] modification of T odd's [10] technique.…”