Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 44-year-old woman sustained massive pulmonary embolization from a deep leg-vein thrombosis. She was given 70 mg recombinant tissue plasminogen activator (rt-PA) by continuous intravenous drip over two hours. Before this treatment perfusion scintigraphy had demonstrated complete absence of flow in the right lung due to embolic occlusion of the central hilar vessels. In addition there were several segmental filling defects in the left lung. Even during the two-hour infusion the circulatory state began to improve, as did echo- and electrocardiographic signs of acute right heart strain. Correspondingly there was a rapid raise in arterial pO2. Another scintigraphy after 48 hours revealed almost complete reperfusion of the right lung and the left lung segments. This case demonstrates that infusion of rt-PA can be an effective and relatively risk-free method of treating haemodynamically significant massive lung embolism, even in comparison with selective or systemic thrombolysis with urokinase or streptase or with surgical embolectomy.
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PMID:[Systemic lysotherapy using recombinant tissue plasminogen activator for fulminant pulmonary embolism]. 210 79

Murine hybrid hybridomas secreting bispecific monoclonal antibodies (bs mAbs) were constructed by fusing hybridomas secreting an anti-tissue plasminogen activator (tPA) or anti-urokinase (UK) mAb with hybridomas secreting a mAb which binds to human fibrin but not to fibrinogen. The bs mAbs reactive to both fibrin and PA (tPA or UK) were purified by affinity chromatography employing the respective antigen-coupled columns and characterized by fibrin-binding, amidolytic and fibrinolytic assays. Immunochemical conjugation of PAs and the bs mAbs did not impair the catalytic activity of PAs at all and made it possible to concentrate PAs on fibrin clot. Pretreatment of fibrin with the bs mAbs enhanced the fibrin-binding of PAs and the subsequent fibrinolysis.
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PMID:Enhancement of fibrinolysis by bispecific monoclonal antibodies reactive to fibrin and plasminogen activators. 210 1

Single-chain urokinase plasminogen activator (scu-PA) that had been modified with N-succinimidyl-3-(2-pyridyldithio)propionate was covalently linked by disulfide bonds to the Fab' of a monoclonal antibody specific for the beta-chain of fibrin (antibody 59D8). scu-PA-59D8 Fab' conjugate was separated from free scu-PA and two-chain urokinase coupled to 59D8 Fab' by two-step affinity chromatography. First, the reaction mixture was chromatographed on a column containing Sepharose linked to the peptide that had been used as immunogen for antibody 59D8; scu-PA-59D8 Fab' conjugate and unconjugated 59D8 Fab' were retained but not unconjugated scu-PA. Then, the eluate from the peptide-Sepharose column was chromatographed on a column containing Sepharose linked to benzamidine, which acts as a ligand for two-chain urokinase. The molecular weight of the scu-PA-59D8 Fab' conjugate was approximately 100 kDa when electrophoresed on a nonreducing sodium dodecylsulfate-polyacrylamide gel. Enzymatic assay after purification revealed that more than 97% of the scu-PA present in the conjugate retained the single-chain form. The Fab' portion of the conjugate functioned in a manner indistinguishable from that of native antibody 59D8. In an in vitro assay for lysis of fibrin monomer, the fibrinolytic potency of scu-PA-59D8 Fab' was 33-fold more than that of tissue plasminogen activator (p less than 0.001), 230-fold more than that of unconjugated scu-PA (p less than 0.0001), and 420-fold more than that of urokinase (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Conjugation to antifibrin Fab' enhances fibrinolytic potency of single-chain urokinase plasminogen activator. 211 44

Urokinase and streptokinase are commonly used thrombolytic agents for fibrin obstructed central venous catheters. Although proven to be efficacious, these two agents have the potential to induce systemic fibrin breakdown and hemorrhage. We report our initial experience with tissue plasminogen activator (t-PA) for the treatment of occluded central venous catheters which failed urokinase. Of 25 incidents of catheter occlusion in 142 right atrial catheters, six failed to clear after an initial bolus dwell of urokinase. Five of these six catheters cleared following treatment with 2 mg/2 cc of t-PA with a mean of 1.5 bolus installations. The one catheter failure was due to catheter tip position and age of clot. No coagulation abnormalities or bleeding was observed. These data suggest that t-PA may be a safe, effective thrombolytic agent in the treatment of occluded central venous catheters.
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PMID:Investigational use of tissue plasminogen activator (t-PA) for occluded central venous catheters. 211 48

The concentrations of tissue plasminogen activator (t-PA) and urokinase (UK) were measured in the plasma of patients with benign or malignant ovarian and uterine tumors. Plasma levels of t-PA were higher in patients with malignant ovarian and uterine tumors than in patients with benign tumors. Plasma UK levels were, however, not different between patients with ovarian and uterine tumors (benign or malignant) and normal persons. The concentrations of t-PA and UK of tissues of uterine myoma were lower than those in normal uterine muscular layer. UK levels of tissues of endometrial and cervical cancers were significantly higher than those in normal endometrium and uterine cervix, whereas t-PA levels were not different between these tumors compared with those in normal uterine tissues.
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PMID:The concentration of tissue plasminogen activator and urokinase in plasma and tissues of patients with ovarian and uterine tumors. 211 90

In this report, we have examined the effects of platelets on plasminogen activation by different activators. Platelets enhance activation of plasminogen by both 1- and 2-chain tissue plasminogen activator (t-PA). The primary effect of platelets is to lower the Km with a corresponding 5-8-fold increase in the kcat/Km. The effect is saturable with respect to the platelet concentration. Platelets enhance activation of both glu- and lys-plasminogen by t-PA. Platelets have no effect on plasminogen activation by streptokinase, and high and low molecular weight urokinase. Thus, there are marked differences in the effects of platelets on plasminogen activation depending on the plasminogen activator. These differences are likely to reflect differences in the interaction between platelets and the plasminogen activators.
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PMID:Differential effect of platelets on plasminogen activation by tissue plasminogen activator, urokinase, and streptokinase. 211 91

In order to identify the regions of recombinant (r) tissue plasminogen activator (tPA) that mediate its kinetically relevant interaction with r-plasminogen activator inhibitor-1 (rPAI-1), we have determined the second-order association rate (k1) constants of domain-altered variants of tPA with rPAI-1, at 10 degrees C. With two-chain, wild-type recombinant tPA (tcwt-rtPA), obtained by expression of the human cDNA for tPA in five different cell systems (viz. insect cells, human kidney 293 cells, Chinese hamster ovary cells, human melanoma cells, and mouse C127 cells), the average k1 was 1.45 x 10(7) M-1 s-1 (range, 1.34 10(7) M-1 s-1-1.68 x 10(7) M-1 s-1). Since this value was not significantly different for the different tcwt-rtPA preparations, it appears as though the nature of the glycosylation of tPA plays little role in its initial interaction with PAI-1. The k1 determined for tcwt-rtPA was slightly higher than that of 0.87 x 10(7) M-1 s-1, obtained for a similar inhibition of human urokinase by rPAI-1. The k1 value obtained for single-chain (sc) wt-rtPA was approximately 6-fold lower than that of the two-chain molecules, results consistent with previous conclusions on this matter. The k1 value for tcwt-rtPA was not influenced by the presence of epsilon-aminocaproic acid, suggesting that the lysine-binding site associated with the kringle 2 (K2) region of tPA does not modulate the rate of its initial interaction with rPAI-1. Removal of the K2 domain from tPA, by recombinant DNA technology, results in a protein, F-E-K1-P (tc-r delta K2-tPA), containing only the finger (F), growth factor (E), kringle 1 (K1), and serine protease (P) domains. This variant protein was more rapidly inhibited by rPAI-1 (k1 = 3.00 x 10(7) M-1 s-1) than its wild-type counterparts. Deletion of both the K1 and K2 domains resulted in a variant molecule, F-E-P (tc-r delta K1 delta K2-tPA), that was slightly more rapidly inhibited by rPAI-1 (k1 = 2.01 x 10(7) M-1 s-1).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Structural determinants of the noncatalytic chain of tissue-type plasminogen activator that modulate its association rate with plasminogen activator inhibitor-1. 211 57

The experiments described in this paper were designed to examine the specific binding of tissue plasminogen activator (tPA) to cultured human aortic endothelial (HAE) cells. When 125I-labelled tPA was incubated with the cells at 4 degrees C, binding was found to plateau within 90 min after incubations were begun. Binding was saturable and the bound enzyme dissociated from the sites with a half-time of approx. 48 min. Scatchard analyses were performed using tPA molecules isolated from human melanoma and colon cells as well as from C127 and Chinese hamster ovary cells that had been transfected with the human tPA gene. These enzymes showed very similar binding characteristics in spite of the fact that they differ substantially in the types of sugars which comprise their side chains. Neither the chainedness of the molecules (one-chain or two-chain) nor the sites at which they are glycosylated (type I or type II) appear to affect their ability to interact with binding sites. The tPA molecules were found to have an average equilibrium dissociation constant of (1.15 +/- 0.10) x 10(-9) M and HAE cells appeared to have a single, homogeneous population of independent binding sites present at a concentration of (1.57 +/- 0.13) x 10(6) sites per cell. Lowering the pH of the binding buffer from 7.4 to 6.5 resulted in a reversible increase in specific binding of between 2-fold and 7-fold depending upon the particular preparation of cells. Preincubation of tPA with plasminogen activator inhibitor 1 (PAI-1) was found to have little effect on binding, suggesting that tPA interacts at sites distinct from surface-bound PAI-1. No evidence for either internalization or degradation of tPA was observed in assays run at 37 degrees C. This suggests that, like urokinase, tPA remains on cell surfaces for an extended period of time.
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PMID:Binding of tissue plasminogen activator to human aortic endothelial cells. 211 40

The search for a simple affinity ligand to purify tissue plasminogen activator (tPA) was facilitated by a solid-phase synthesis approach. A large variety of tripeptide ligands containing argininal were synthesized on agarose gels containing a spacer with carboxy terminal. The immobilized ligands were easy to test with urokinase, and tPA. While a number of sequence combinations showed initial binding by tPA, only a few resulted in tight binding corresponding to a hemiacetal linkage with the active site serine. Hydrophobic residues, especially aromatics, flanking the N-side of argininal gave rise to ligands which were bound strongly by tPA. A gel containing D-Phe-D-Phe-Argal (an aldehyde derivative of arginine) was very effective in purifying tPA derived from cell culture media at small scale (milligrams) and at large (multi-grams).
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PMID:Affinity purification of tissue plasminogen activator using transition-state analogues. 211 88

Recombinant tissue plasminogen activator (rt-PA) is a thrombolytic agent characterized by elevated but not absolute fibrin specificity. However, its therapeutic dose is high and associated with a variable degree of systemic activation of the fibrinolytic system. Thrombolytic drugs are widely used in acute myocardial infarction and have now begun to be considered for deep vein thrombosis (DVT), pulmonary embolism (PE), and peripheral artery thrombosis (PAT) as well. Although anticoagulant therapy is effective in reducing the immediate complications of venous thromboembolism, thrombolytic therapy has various advantages over anticoagulant therapy, including lysis of thrombi with recanalization of venous circulation, reduction of venous valve damage and prevention of post-phlebitic syndrome. The different dosage regimens of rt-PA recently evaluated (0.71 to 1.76 mg/kg/24 h for 2-4 days) in DVT have caused consistent thrombolysis but also excessive bleeding. The optimal therapeutic range for rt-PA in DVT remains to be determined. Thrombolytic therapy is superior to heparin treatment only in hemodynamically compromised patients with massive PE. The minor systemic fibrinolytic effect and the faster action on thrombi of rt-PA compared with the first generation thrombolytic agents, streptokinase (SK) and urokinase (UK), are very interesting and explain the positive results recently obtained in PE with this drug (50 mg over 2 h, followed, if necessary, by 40-50 mg over 4-5 h) by Goldhaber and Verstraete.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[rt-PA in extracardiac thromboembolic vascular occlusions]. 211 73


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