The “lysometer”: An automated device for the detection of fibrin dissolution, in vitro

Abstract

The clot-lysis timing device consists of an electronic recording system and 24 controlled temperature sample wells. A 1.5–2.5 ml. clot is formed in a test tube by the addition of thrombin to plasma (or to a mixture of fibrinogen and plasminogen) containing varying quantities of urokinase, streptokinase or plasmin). Pre-cooling prevents enzymatic activity until the tube is placed in one of the 37 °C wells. A mechanical switch (at the base of each well) is a polled input to a computer. An opaque plastic sphere is placed on top of the clot. As the clot dissolves, (rate dependent on the quantity of lytic agent incorporated in the clot), the sphere travels to the bottom of the tube, interrupting an infrared light beam, which is another polled input to a computer. Each channel can be independently displayed on an L.E.D. readout. A four (or more) point standard curve (in duplicate) and four concentrations of an unknown (in duplicate) can be analyzed simultaneously. The instrument has been used successfully in the determination of the potency of urokinase, streptokinase and plasmin solutions.