[Study of the role of tryptophan residues in streptokinase molecules using a chemical modification method]

Incubation of streptokinase in an H2O2-dioxane-bicarbonate buffer (pH 8.5) system leads to the oxidation of tryptophan residues as can be evidenced from the changes in absorption and tryptophan fluorescence spectra. A complete oxidation of tryptophan residues of the protein takes place within 3 hours, the number of the residues is 4. The first tryptophanyl of the protein is oxidized the most easily; the activity of streptokinase decreases thereby by 50%. Modification of the second residue leads to complete inactivation of streptokinase. The rate constants for the oxidation of the first, of the two first and of the third plus fourth tryptophanyls are equal to 1.5.10(-2) min-1, 1,1.10(-2) min-1 and 0.5.10(-2) min -1, respectively. The complete oxidation of tryptophan residues is concomitant with the inability of streptokinase to form stable equimolar complexes with human plasminogen, but in does not result (as can be judged from the CD spectroscopy data) in the breakdown of the protein secondary structure. The specificity of oxidation of the protein tryptophan residues is discussed. The importance of readily oxidized tryptophan residues for the streptokinase function is postulated.

[Effect of adenine nucleotides on the activator function of streptokinase]

The addition of ATP or 3,5-AMP (but not UTP, GTP, CTP, AMP, 2,3-AMP, ADP, inorganic pyrophosphate) at a final concentration of 10(-1) M into streptokinase solution, pH 7.0 or 9.5, causes a dramatic inhibition of streptokinase-induced fibrinolysis. The specificity of ATP effect is fully lost at pH 3.0, when all nucleotides completely inhibit the activating function of streptokinase. Ribose-5-phosphate causes a similar effect at pH 3.0. The character of nucleotide action on the activating function of streptokinase considerably differs from their influence on proteolytic reactions.

Inhibition of fibrinolytic system by liquoid (polyanetholesulfonate). A contributing factor in the liquoid-induced renal cortical necrosis

Liquoid induces microvascular thrombosis and renal cortical necrosis in experimental animals. We hypothesized that thrombosis and renal cortical necrosis may, at least in part, result from the inhibition of the fibrinolytic system by liquoid. Effects of liquoid on plasminogen activation by rat kidney, purified human tissue plasminogen activator (TPA), urokinase, streptokinase, and on the amidolytic activities of TPA, urokinase, and plasmin were studied using chromogenic substrates and clot lysis. Liquoid had a strong inhibitory effect on the fibrinolytic system in vivo and in vitro. The inhibition was most effective at the plasminogen activation level, with activation by streptokinase being most susceptible. The demonstrated stoichiometric binding between liquoid and plasminogen, and to a lesser degree the direct inactivation of plasminogen activators and plasmin, is probably responsible for the reduction of plasminogen activation in circulation and in the kidneys.

[Molecular mechanisms of fibrinolysis and perspectives of thrombolytic therapy]

Modern data on biochemistry of fibrinolysis, molecular mechanisms for interaction of plasmin with fibrin and antiplasmins are discussed. Perspectives of thrombolytic therapy are considered. Evidence for selective action of plasmin, bound with alpha 2-macroglobulin, on fibrin offers new opportunities in research on newer effective thrombolytic drugs.

The binding of tumor localizing porphyrins to a fibrin matrix and their effects following photoirradiation

The binding of two tumor localizing porphyrins, meso-tetra (4-carboxyphenyl) porphine (TCPP) and meso-tetra (4-sulfonatophenyl) porphine (TPPS4) to fibrin clots was determined in vitro. Both TCPP and TPPS4 were found to bind extensively, although weakly, to fibrin. No appreciable binding by Hematoporphyrin IX to the fibrin matrix was detectable. Similar results were obtained whether the clot was non-crosslinked or crosslinked with factor XIII. Photoirradiation of a porphyrin-impregnated non-crosslinked clot rendered it urea insoluble. Electrophoretic analysis indicated that the alpha chain of the fibrinogen molecule was most affected by photoirradiation. This was manifested as a loss of the alpha chain intensity and a concomitant increase of high molecular weight components, suggesting the formation of crosslinks. No substantial differences were noted in susceptibility to plasmin lysis between photoirradiated and non-irradiated clots. Photoirradiated clots were, however, significantly more resistant to lysis induced by the plasminogen activators urokinase and streptokinase, suggesting that inactivation of plasminogen within the clot matrix had occurred during photoirradiation. The relevance of porphyrin binding to fibrin with regard to tumor localization and destruction is also discussed.

[What emergencies arise from anticoagulant therapy?]

The antithrombotics (fibrinolytics, anticoagulants and aggregation inhibitors) belong to the most effective therapeutic methods and are used in all clinical specialties. The therapeutic mechanism of the fibrinolytics and anticoagulants is recognizable and can be regulated by hepatic parameters. Nevertheless, under this treatment patients undergo a potential risk of haemorrhage which not in every case can be estimated with the usual laboratory parameters. In addition to the factors increasing the potential risk false behaviour of the physician in charge and false behaviour on the side of the patient must be mentioned. In these two cases a treatment with antithrombotics should be omitted. If personal and technical insufficiencies are present the patient should be transferred to a centre for further treatment. In acute indications for discontinuing the treatment with antithrombotics depending on the clinical urgency a gradually different discontinuation by stages should be striven for, in order to avoid thromboembolic relapses.

[Serodiagnosis of rheumatic disorders]

For the serological diagnostics of the diseases caused by Streptococcus pyogenes (A-streptococci) and secondary diseases (rheumatic fever, acute glomerulonephritis) in the first place the anti-streptolysin reaction is at disposal. In the judgment age is to be taken into consideration and the proportion of the inhibitor in the serum is to be removed by absorption with dextran sulphate. Reliable evidence is to be expected only by the course of the titre. If possible, the antistreptolysin reaction should be supplemented by a second reaction, for which purpose the anti-desoxyribonuclease B-reaction is to be recommended. For supporting the diagnostics of the rheumatoid arthritis at least 2 reactions should be performed, i. e. a haemagglutination test (e. g. after Podliachouk-Harboe) and a particle agglutination test (latex fixation reaction). By means of them the rheumatoid factors (above all antibodies of the IgM-class against gamma-globulin) are proved. The haemagglutinations connect a high specifity with a more insignificant sensitivity, in the particle agglutinations the reverse is the case. Apart from the serological tests mentioned here other proved reactions are mentioned. Besides, data on the valuation of the results and their diagnostic importance are in this paper.

[Resistance test to streptokinase. Its value in the establishing of a thrombolytic treatment using this enzyme]

The reckoning of the rate of serous anti-streptokinase (ASK) evidenced that 8 p. 100 of the test-sample presented a distinct resistance to Streptokinase (SK), and that this percentage could be more important under certain pathological circumstances. On account of this fact and also because SK injectable preparations may offer a variation in activity, the writers advocate a "preliminary control in vitro" by means of the resistance test to streptokinase that enables one to make sure, for each patient, of the biological efficacy of the drug and to specify the starting posology.

[Comparison of the streptozyme test with titration of antistreptolysin, antistreptokinase and antistreptohyaluronidase]

Streptozyme is a new serologic assay which is able to evidentiate 5 antistreptococcal antibodies at the same time (TAS, ASHA, ASK, DNase, NADase). This test has been carried out on 355 samples together with TAS, ASK and ASHA methods in order to value this method comparatively. The results showed that Streptozyme is a poorly reliable technique, looking at the false-positive or negative results obtained, but principally looking at the phenomena of no good reproducibility. We feel that at present it cannot be used in substitution of the classic serologic methods.

[Theoretical bases of thrombolytic therapy]

Purified streptokinase has in vitro a double biochemical activity on plasminogen. At a low molecular ratio of streptokinase/plasminogen, mainly plasmin is generated. At an equimolar streptokinase-plasminogen ratio, mainly a complex streptokinase-plasmin is formed. This complex has a low proteolytic activity but has a high activator activity on plasminogen and maintains esterolytic properties. It is likely that the reactions occurring in vitro with purified reagents also occur in vivo, the situation being nevertheless more complex because of the presence of inhibitors such as antistreptokinase and antiplasmins.

[Effect of [ethyl p-(6-guanidinohexanoyloxy)benzoate] methanesulfonate (FOY) on kinin formation and fibrinolysis activity]

Inibitory effects of [Ethyl p-(6-guanidinohexanoyloxy)benzoate] methanesulfonate (FOY) on kinin formation (in vitro and in vivo) and the fibrinolytic activity (in vivo) were examined and compared with otherinhibitors. Inhibitory effect on kinin forming activity (in vitro) of various enzymes was measured in the guinea pig ileum. FOY and Trasylol inhibited the kinin forming activities of trypsin, pancreas kallikrein and plasma kallikrein. Soybean trypsin inhibitor inhibited kinin like substance was formed in the perfusate when the rat's paw was heated at 46 degrees C. FOY and T-asylol added to the perfusion fluid produced a potent inhibition of the formation of bradykinin-like substance. When administered i.v., FOY and Trasylol did not inhibit the formation of bradykinin-like substance. In the dog, activation of plasmin in the circulatory blood and increase of hemorrhagic tendency were caused by the i.v. administration of human serum plus streptokinase. Such responses were inhibited with a previous i.v. infusion of FOY and t-AMCHA. From the above findings, it may be concluded that FOY has inhibitory effects on kinin formation and fibrinolytic activity.

In vitro effects of aspirin in fibrinolysis

In <i>in vitro</i> studies, aspirin inhibited the lytic activity of streptokinase (SK), urokinase (UK), plasmin, and of euglobulins prepared from normal and Hageman deficient human plasmas. Aspirin also inhibited the generation of activator activity in the plasminoplastin generation test assay. This anti-fibrinolytic effect of aspirin was not due to its acid pH. Chicken plasma being deficient in Hageman factor and in proactivator exerted also a very potent anti-SK and anti-UK effect.