M. Mason Guest

Blood Viscosity: Influence of Erythrocyte Aggregation

The addition of purified canine or bovine fibrinogen to suspensions of canine erythocytes in Ringer solution caused an increase in viscosity and the formation of aggregates of erythocytes. Both of these effects became increasingly pronounced as the fibrinogen concentration was raised, and they approached plateaus with 1 gram of fibrinogen per 100 milliliters. An increase in shear rate (or shear stress) reduced both the effect on viscosity and the aggregate size. The data suggest that fibrinogen causes an increase in blood viscosity and a departure from Newtonian behavior by interacting with erythrocytes to form cell aggregates which can be dispersed by shear stress.

The biochemistry and physiology of urokinase

Abstract Development of methods for isolating, purifying and assaying urokinase, the urinary enzyme activator of plasma profibrinolysin, is described. Properties of the enzyme are given and the unit of activity is defined and related to units of other workers. Studies of urokinase excretion are reported and note made of limitations which must be imposed on interpretation of variations in amount of enzyme excreted. Of particular importance is the possible existence of more than one molecular species of urokinase. Plasma profibrinolysin preparations obtained from representatives of species ranging from man through lower mammals to fish can be activated by human urokinase. Profibrinolysin preparations from pig plasma are susceptible to urokinase activation only following removal of inhibitors. Human urokinase has been used as a major tool in the detection of profibrinolysin in a variety of plasma protein preparations and in the development of procedures designed to remove profibrinolysin from such preparations as fibrinogen and thrombin. Human urokinase injected into heterologous species has been shown to be an antigen. This property has been utilized to demonstrate that parenterally administered human urokinase is excreted in the urine of injected rabbits with no apparent alteration in either enzymatic or immunologic characteristics.

Profibrinolysin, antifibrinolysin, fibrinogen and urine fibrinolytic factors in the human subject.

This report describes methods for the quantitative assay of human plasma profibrinolysin (plasminogen) and for the semi-quantitation of fibrinolytic factors in urine. The concentrations of plasma profibrinolysin, antifibrinolysin, fibrinogen and lytic factors in urine of patients with an active neoplasm and in pregnant women are compared with their concentrations in normal individuals.

On the interaction of fibrinolysin (plasmin) with the inhibitors antifibrinolysin and soybean trypsin inhibitor

Abstract A turbidimetric technique was used to measure the activity of fibrinolysin (FL). The substrates used were fibrinogen and the fibrin derivatives produced during visual lysis of fibrin. With fibrinogen as a substrate, the Michaelis constant was estimated to be 3.6 × 10 −5 M . Inhibition of fibrinolysis and the process after visual lysis was obtained with crystalline soybean trypsin inhibitor and an antifibrinolysin preparation from bovine plasma (estimated M.W. 57,000). Th calculated dissociation constant of the complex between FL and antifibrinolysin was 7 × 10 −7 . The dissociation constant for the complex between FL and trypsin inhibitor must be considerably less. Effects of heparin and epsilon-amino-caproic acid were also studied. We have estimated that at low FL concentrations in plasma the concentrations of bound FL is one hundred times larger than the concentration of free FL. The increase in lysis times in the presence of inhibitors can be partly reversed with mercurials.

Cinemicrographic observations of the effects of contrast media on the microcirculation.

* Supported in part by a grant from The Texas Heart Association. † Department of Thoracic and Cardiovascular Surgery, University of Texas Medical Branch, Galveston, Texas. ‡ Department of Physiology, University of Texas Medical Branch, Galveston, Texas. ’ Angiography has found increasing usefulness in the evaluation of vascular related pathology. Since the introduction of iodinated compounds for arteriography by Brooks in 1924,1 continued refinement in contrast media has progressively improved the safety of these procedures. Much of this progress has been made possible by extensive investigation into the potential toxicity of these compounds. Excluding anaphylactic reactions, early investigators believed additional damaging effects of x-ray dyes were secondary to reflex vasoconstriction.2> 3 Wore recently attention has been focused on the effect of the contrast material on blood cellular elements .4-9 High speed cinematography afforded the opportunity of studying the effects on the vascular physiology of the microcirculation. In addition, by projecting the recorded high speed film at a rate 100 times slower than the original filming sequence it

Release of thromboplastin after thermal injury.

Microcirculatory flow following a severe burn is hindered by the formation of aggregates of erythrocytes which frequently completely fill the lumena of small arteries, arterioles, and venules. On the arterial side, clusters of cells are often too large to enter branching vessels; large aggregates grow from smaller clusters, and vessels fill with packed, adherent erythrocytes for some distance proximal to divarications. However, if erythrocytes enter capillaries, they move independently of other erythrocytes and are transformed into hollow paraboloids as they are in the absence of trauma to tissue or in the absence of infused thromboplastin.

Factors influencing susceptibility of fibrin and fibrinogen to proteolysis by fibrinolysin.

Abstract Regardless of incubation temperature, a delay of 5 min. in the formation of clots from fibrinogen solutions, containing the fibrinolysins of man, dog, or cow, always results in a prolongation of the time required for lysis of the clots. The comparative rates of release of tyrosine in the early stages of proteolysis appear to furnish added evidence that fibrin is more rapidly proteolyzed by fibrinolysin than is fibrinogen. The data presented in this report tend to substantiate the postulate that the formation of a clot in the presence of fibrinolysin results in the adsorption of all or part of the fibrinolysin and protection of it against the action of antifibrinolysin. The adsorbed fibrinolysin brings about the degradation of the clot regardless of the presence of antifibrinolysin. Profibrinolysin is not adsorbed during clot formation.

Coagulation and fibrinolytic studies in women receiving an anovulatory drug (medroxyprogesterone acetate with estradiol)

Abstract In 16 women receiving Provest who were subjected to a controlled study of clinical manifestations and laboratory assays of coagulation and fibrinolytic components: 1. 1. Significant differences in blood coagulation and fibrinolytic components throughout treated and untreated menstrual cycles in 8 patients were not detected. 2. 2. Medroxyprogesterone with ethinyl estradiol was an effective oral contraceptive. 3. 3. Side effects, with the possible exception of breakthrough bleeding, were minor. No evidence of thrombotic phenomena or masculinization was found.

Stability of Fibrin Contiguous to Intima of Veins

A technique is described which employs an everted segment of canine jugular vein to study the effect of the intima on contiguous fibrin. Following eversion of the vein on a stainless steel rod of suitable dimensions, the vein was coated with a layer of fibrin by winding it onto the endothelial surface. The rate at which soluble Folin-Ciocalteu reactive material appeared in the incubated media of clots so prepared was significantly higher than that developed in systems containing either everted vein alone or fibrin alone. EACA suppressed the liberation of soluble tyrosine from contiguous fibrin but was without effect on the liberation of soluble Folin-Ciocalteu reactive material from the vein alone.

Distribution of urokinase among the common mammals.

Urokinase, a principle capable of activating profibrinolysin to fibrinolysin, has been found in the urine of the cat, rat, cow, rabbit, man, dog and hamster. Soluble concentrates of this activator were prepared by precipitation of urine with equal volumes of cold acetone, suspension of the precipitate in borate buffer and sequential dialysis of the suspension against borate buffer (ph 9.2), distilled water and phosphate buffer (ph 7.25). The ability of the urokinase concentrates from the urine of a given species to activate the profibrinolysin of its own and various other species was measured in a two-stage assay system which is described. The activation of profibrinolysin by urokinase was limited by definite species specificities and did not appear to involve the intermediation of a plasma prokinase.