Plasma Plasminogen Concentrations Research Articles

Fribrinolysis kinetics and its application

A new, convenient, and rapid method for kinetic measurement of human fibrinolysis was established. The alteration of absorbance (A) in the process of blood coagulation and lyses was automatically scanned and recorded using a UV2000 spectrophotometer connected to a computer. The parameters of human fibrinolysis kinetics were established. Urokinase at 20 U/mL was the optimal concentration used. There was significant difference in fibrinolysis kinetics and plasma plasminogen concentration between 22 normal subjects and 27 patients with acute myeloblastic leukemia (P<0.05 and <0.01 respectively). The coefficience of variation was (5.24+/-1.51)%. This method could also be used to measure the plasma fibrinogen concentration at the same time. It was concluded that this method was stable and was capable of providing dynamic, direct experimental data and multiparemeters for clinicians. It was also valuable in evaluating the anti-and pro-fibrinolytic capcity of patients' plasmas, allowing for monitoring of therapy, choice of drugs and adjustment of drug concentrations.

Evidence that Modifications of Lp(a) In Vivo Inhibit Plasmin Formation on Fibrin

In the present study we have investigated the effect of individual variations in the concentration of Lp(a) on plasmin formation at the surface of fibrin. The plasma Lp(a) concentrations from 20 nephrotic children were high at flare-up of the disease (0.43+/-0.45 g/l) and decreased progressively with remission at both 6 weeks (0.28+/-0.24 g/l) and 6 months (0.24+/-0.288 g/l). In contrast, the concentration of plasminogen showed an inverse variation, with low values at flare-up (1.27+/-0.34 microM) and normal values at remission (1.66+/-0.17 microM at 6 weeks and 1.99+/-0.21 microM at 6 months). An increase in plasmin formation (from 0.62+/-0.49 to 0.73+/-0.61, and 0.84+/-0.75 pmol/well) and a decrease in apo(a) binding (from 5.45+/-2.42 to 4.54+/-2.12, and 3.93+/-1.51 fmol/well) on the surface of fibrin, were concomitantly observed from flare-up to remission at 6 weeks and at 6 months, respectively. Values for plasmin formation parallel the amount of plasminogen bound. The low concentration of plasminogen found at flare-up may also have contributed to the increased binding of Lp(a) as indicated by a decrease in the maximal amount of Lp(a) bound (Bmax) to fibrin as a function of plasma plasminogen concentrations. Bmax was 1.51 fmol in the absence of plasminogen and decreased to 1.1 fmol and 0.93 fmol at respectively 1 and 2 microM of plasminogen. Altogether, these data constitute the first quantitative evidence indicating that plasmin formed at the surface of fibrin may vary with modifications of the concentration of Lp(a) in vivo.

Plasma crosslinked fibrin polymers: quantitation based on tissue plasminogen activator conversion to D-dimer and measurement in normal and patients with acute thrombotic disorders

Plasma crosslinked fibrin polymers (XLFP) are formed as a result of in vivo hemostatic activation and are elevated in thrombotic disease. We have investigated the plasmic degradation of plasma XLFP in vitro to provide information regarding the pattern of crosslinking and the composition of degradation products. Plasma XLFP were identified by sodium dodecyl sulfate (SDS)-agarose electrophoresis and Western blotting and quantitated by gel scanning. D-dimer was measured by enzyme-linked immunosorbent assay and the results were verified by SDS-polyacrylamide gel electrophoresis and Western blotting of the digests. Complete degradation of XLFP occurred only after supplementation of plasma with plasminogen (5 U/mL) and incubation with recombinant tissue plasminogen activator (rt-PA), indicating that the normal plasma plasminogen concentration limits plasmic degradation in vitro. Gel electrophoresis showed that the principal terminal degradation products of XLDP were fragments D, DD, and E, indicating that crosslinking occurred primarily through gamma chain dimers. After adding a low concentration of thrombin to plasma in vitro, XLFP increased progressively before clotting, and the concentration correlated with the increase in the D-dimer concentration after degradation (r = .98). Plasma XLFP and D-dimer concentrations in plasmic digests were significantly elevated in patients with stroke (150 +/- 83 micrograms/mL and 88 +/- 32 micrograms/mL), myocardial infarction (217 +/- 110 micrograms/mL and 84 +/- 30 micrograms/mL), and venous thrombosis (187 +/- 80 micrograms/mL and 86 +/- 19 micrograms/mL) compared with normals (28 +/- 12 micrograms/mL and 25 +/- 7 micrograms/mL). There was a strong correlation between the plasma concentration of XLFP and the D-dimer immunoreactivity of plasma after plasmic degradation (r = .87). The results indicate that XLFP in plasma are crosslinked primarily through gamma chains and degrade to fragment DD with plasminogen activation. Also, the immunoreactivity of in vitro plasmic digests of plasma reflects the concentration of XLFP and may provide a useful indirect measure of in vivo hemostatic activation in patients with thrombotic disease.

Plasma Crosslinked Fibrin Polymers: Quantitation Based on Tissue Plasminogen Activator Conversion to D-Dimer and Measurement in Normals and Patients With Acute Thrombotic Disorders

Abstract Plasma crosslinked fibrin polymers (XLFP) are formed as a result of in vivo hemostatic activation and are elevated in thrombotic disease. We have investigated the plasmic degradation of plasma XLFP in vitro to provide information regarding the pattern of crosslinking and the composition of degradation products. Plasma XLFP were identified by sodium dodecyl sulfate (SDS)-agarose electrophoresis and Western blotting and quantitated by gel scanning. D-dimer was measured by enzyme-linked immunosorbent assay and the results were verified by SDS- polyacrylamide gel electrophoresis and Western blotting of the digests. Complete degradation of XLFP occurred only after supplementation of plasma with plasminogen (5 U/mL) and incubation with recombinant tissue plasminogen activator (rt-PA), indicating that the normal plasma plasminogen concentration limits plasmic degradation in vitro. Gel electrophoresis showed that the principal terminal degradation products of XLDP were fragments D, DD, and E, indicating that crosslinking occurred primarily through gamma chain dimers. After adding a low concentration of thrombin to plasma in vitro, XLFP increased progressively before clotting, and the concentration correlated with the increase in the D-dimer concentration after degradation (r = .98). Plasma XLFP and D-dimer concentrations in plasmic digests were significantly elevated in patients with stroke (150 +/- 83 micrograms/mL and 88 +/- 32 micrograms/mL), myocardial infarction (217 +/- 110 micrograms/mL and 84 +/- 30 micrograms/mL), and venous thrombosis (187 +/- 80 micrograms/mL and 86 +/- 19 micrograms/mL) compared with normals (28 +/- 12 micrograms/mL and 25 +/- 7 micrograms/mL). There was a strong correlation between the plasma concentration of XLFP and the D-dimer immunoreactivity of plasma after plasmic degradation (r = .87). The results indicate that XLFP in plasma are crosslinked primarily through gamma chains and degrade to fragment DD with plasminogen activation. Also, the immunoreactivity of in vitro plasmic digests of plasma reflects the concentration of XLFP and may provide a useful indirect measure of in vivo hemostatic activation in patients with thrombotic disease.

Comparison of fibrinolytic and amidolytic methods for the measurement of streptokinase pharmacokinetics in patients with acute myocardial infarction

Plasma samples were obtained from 12 AMI patients administered SK (1.5 × 10 6iu by 1 h infusion) and the plasma levels of SK activity were measured by fibrinolytic and amidolytic assays. Although plasma plasminogen concentrations declined rapidly after the start of infusion there appeared always to be sufficient residual plasmin(ogen) present for activator complex formation. Calibrated fibrinolytic (human fibrin plates) and CNBr-fibrinogen fragment-stimulated amidolytic (S-2251) assays of plasminogen activator activity in euglobulin fractions gave a consistent estimate of SK pharmacokinetics. The peak level of activity (approximately 175 IU/ml plasma) was achieved at the end of the infusion period and activity was cleared with a half-life of approximately 29 min for the majority ( > 80%) of the dose. These values were not affected by the level of pretreatment anti-SK antibody (IgG). It was not possible to quantify SK levels, using bovine fibrin plates because the changing content of human plasminogen in the samples variably affected the lytic response. Measurement of plasma amidolytic activity (when plasmin is inhibited) also did not give a reliable estimate of pharmacokinetics, partly because of interference by plasmin- α 2 macroglobulin complex.

Binding of plasminogen to extracellular matrix.

We have previously demonstrated that plasminogen immobilized on various surfaces forms a substrate for efficient conversion to plasmin by tissue plasminogen activator (t-PA) (Silverstein, R. L., Nachman, R. L., Leung, L. L. K., and Harpel, R. C. (1985) J. Biol. Chem. 260, 10346-10352). We now report the binding of human plasminogen to the extracellular matrix synthesized in vitro by cultured endothelial cell monolayers. The binding was specific, saturable at plasma plasminogen concentrations, reversible, and lysine-binding site-dependent. Functional studies demonstrated that matrix immobilized plasminogen was a much better substrate for t-PA than was fluid phase plasminogen as shown by a 100-fold decrease in Km. Activation of plasminogen by t-PA and urokinase on the matrix was equally efficient. The plasmin generated on the matrix, in marked contrast to fluid phase, was protected from its fast-acting inhibitor, alpha 2-plasmin inhibitor. Matrix-associated plasmin converted bound Glu- into Lys-plasminogen, which in turn is more rapidly activated to plasmin by t-PA. The extracellular matrix not only binds and localizes plasminogen but also improves plasminogen activation kinetics and prolongs plasmin activity in the subendothelial microenvironment.

Plasminogen and antithrombin III deficiencies in the childhood nephrotic syndrome associated with plasminogenuria and antithrombinuria

Three of four patients with the childhood nephrotic syndrome were found to have low plasma plasminogen concentrations; all four had low plasma antithrombin III concentrations. In the two patients who were tested, urinary concentrations of these proteins exceeded the plasma concentrations. As the urinary losses of plasminogen and antithrombin III decreased over the course of illness, the plasma concentrations of antithrombin III and plasminogen rose. One patient had multiple thromboembolic episodes. We conclude the deficiencies of antithrombin III and plasminogen, probably secondary to urinary excretion of these proteins, may contribute to the thrombotic diathesis associated with nephrotic syndrome.

Concentration of Plasma Antithrombin III, α2-Macroglobulin, α1-Antitrypsin and Plasminogen in Healthy Japanese

Levels of plasma antithrombin III, α2-macroglobulin, α1-antitrpysin and plasminogen were determined using single radial immuno diffusion method in 269 healthy Japanese ranging from twenty to ninety-four years. Subjects under age sixty were volunteers working in Tokyo Metropolitan Institute of Gerontology. Those over age sixty were randomly selected from population of healthy normals in old people's home in Tokyo.Mean value of plasma antithrombin III of women under age forty was slightly lower than that of men, whereas it was statistically higher in females over age sixty than that of males in corresponding age groups. These facts act advantageously for elderly women concerning protection of thrombosis, theoretically. Plasma antithrombin III levels in subjects of both sexes over age sixty were decreased progressively as the population aged. Plasma antithrombin III concentration was significantly correlated with plasma factor X activity and serum cholesterol levels measurd simultaneously, but not with factor VII-complex activity, indicating that as factor X and/or choresterol levels rise, antithrombin III concentration increases in normal subjects. The presense of these correlations may be favourable for protecting one with elevated factor X or serum cholesterol levels from thrombosis.Concentration of α2-macroglobulin, which acts as an antithrombin and as an antiplasmin simultaneously, was significantly higher in women than in men in all age-matched groups, although the differences diminished as age increased.Levels of α1-antitrypsin, the other important antiplasmin than α2-macroglobulin, were obviously higher in the older subjects than in the youngers.Mean levels of plasma plasminogen concentration of normal women were higher than those of men. Plasminogen concentration of normal subjects decreased progressively with aging after the seventh decade of life, as was already observed in levels of factor VII-complex, factor X, fibrinogen and plasma antithronbin III in healthy Japanese. Levels of plasma plasminogen were significantly correlated with serum cholesterol levels measured simultaneously in healthy subjects over age sixty. A low but statistically significant correlation between plasminogen and α1-antitrypsin content in plasma of healthy older subjects was also observed.From these results, it is postulated that there exists a homeostatic balance between blood clotting or fibrinolytic system and their inhibiting system in healthy subjects, as a whole.

Comparative Studies of the Fibrinolytic System in Rats and Humans

Components of the fibrinolytic system were determined in human and rat plasma. Rat plasma has a significantly higher plasminogen activator content which is counterbalanced by a higher plasmin inhibitor level. The plasma plasminogen concentration is somewhat higher in humans. The trypsin inhibitor did not differ significantly in humans and rats. Identical values for plasminogen were found in human plasma when activated with streptokinase or urokinase. The necessity of a correct streptokinase concentration in the assay system is stressed. From the data presented it is concluded that the rat is a suitable animal to study fibrinolysis under experimental conditions.

Blood fibrinolytic activity during arvin therapy.

Summary:When Arvin is administered to patients, there is a rapid fall in plasma plasminogen concentration and fibrin degradation products appear in the blood which can be detected both by their anticoagulant effect and by their reaction with anti‐fibrinogen serum. There is a minimal but inconstant increase in the concentration of plasminogen activator and circulating plasmin cannot be detected. These findings are similar to those recorded in the defibrination syndrome and are explained by the assumption that both plasminogen and activator are adsorbed onto intravascular fibrin micro‐clots. Local plasmin release would then cause lysis of fibrin with the appearance of fibrin degradation products.There is no apparent reason why this mechanism should assist in the lysis of coexisting preformed thrombi. The apparent rapid lysis of thrombi which has been observed in some patients treated with Arvin can be explained if such thrombi are not static, but represent a balance between fibrin deposition and fibrinolysis. Therapeutic defibrination, by preventing extension of the thrombus, would allow the normal fibrinolytic mechanism to produce dissolution of the thrombus.