Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombospondin is a large, trimeric glycoprotein secreted by activated platelets and growing cells. Thrombospondin copolymerizes with fibrin during blood coagulation and deposits in extracellular matrix. We found that thrombospondin is a slow (rate constant approximately 6.3 x 10(3) M-1 sec-1), tight-binding (Kd < 10(-9) M) inhibitor of plasmin as determined by loss of amidolytic activity, loss of ability to degrade fibrinogen, and decreased lysis zones in fibrin plate assays (Biochemistry 31: 265-269, 1992). Thrombospondin also slowly inhibits urokinase plasminogen activator. The lysis zone when urokinase is put on fibrin plates made from whole plasma is less if thrombospondin is present. The stoichiometry of inhibition is approximately one mole plasmin:one mole thrombospondin trimer, a somewhat surprising result considering the trimeric nature of thrombospondin. These results indicate that thrombospondin is an important regulator of fibrinolysis and degradation of extracellular matrix, particularly when these processes are initiated by urokinase and even when other inhibitors of fibrinolysis are present.
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PMID:Modulation of fibrinolysis by thrombospondin. 130 73

Low molecular weight two-chain urokinase is a 33-kD plasminogen activator, which has no innate affinity for fibrin and consequently, its use to facilitate lysis of blood clots may lead to systemic activation of plasminogen. In order to impart clot affinities to this urokinase form (UK) we have generated two novel fibrin-binding derivatives by partially reducing UK and exchanging the native disulfide-linked peptide A with peptide A analogs. The peptide A analogs contained the fibrin-adherent fibrin-derived sequences, GPRP (derived from positions 17-20 of the fibrinogen alpha chain) or QAGDV (407-411 sequence of the fibrinogen gamma chain), each coupled through amino-hexanoic acid to a synthetic peptide, LKFQCGQK, containing the Leu 144-Lys 158 sequence of the urinary plasminogen activator A Chain. The resultant derivatives contained about 0.4 moles peptide analog/mole UK, were 75% active toward synthetic UK substrates, and were recovered in a nearly 80% yield. The two fibrin peptide derivatives had a five-fold greater affinity for the clots.
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PMID:Insertion of fibrin peptides into urokinase enhances fibrin affinity. 235 45

We have investigated the interaction of alpha 2-macroglobulin (alpha 2M) with the serine proteinase urokinase, an activator of plasminogen. Urokinase formed sodium dodecyl sulfate stable complexes with purified alpha 2M and with alpha 2M in plasma. These complexes could be visualized after polyacrylamide gel electrophoresis by protein blots using 125I-labeled anti-urokinase antibody or by fibrin autography, a measure of fibrinolytic activity. According to gel electrophoretic analyses under reducing conditions, urokinase cleaved alpha 2M subunits and formed apparently covalent complexes with alpha 2M. Urokinase cleaved only about 60% of the alpha 2M subunits maximally at a mole ratio of 2:1 (urokinase: alpha 2M). Binding of urokinase to alpha 2M protected the urokinase active site from inhibition by antithrombin III-heparin and inhibited, to a significant extent, plasminogen activation by urokinase. Reaction of urokinase with alpha 2M caused an increase in intrinsic protein fluorescence and, thus, induced the conformational change in alpha 2M that is characteristic of its interactions with active proteinases. Our results indicate that both in plasma and in a purified system the alpha 2M-urokinase reaction is functionally significant.
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PMID:Structural and functional characterization of the inhibition of urokinase by alpha 2-macroglobulin. 241 80

Dermal nevocytic nevi (NN) were histochemically studied with the help of FITC-conjugated lectins as well as antisera against keratin and plasminogen activators of the urokinase type. 3 out of 18 NN showed interpenetrating nevus cells in atrophic parts of the epidermis. These cells revealed strong lectin reactivity both with Con A (cytoplasmatic binding) and WGA/RCA II (membraneous binding). In addition we found membraneous reaction with anti-urokinase, whereas there was no anti-keratin staining. Our findings suggest active transepidermal elimination of nevus cells in dermal nevocytic nevi.
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PMID:[Histochemical studies of transepidermal elimination of nevus cells in nevus cell nevi of the corium]. 247 58

The lytic therapy using Urokinase (UK) as well as Streptokinase (SK) has a significant risk of complications such as systemic bleeding. We aimed to develop the autologous plasmin (AP) solution as a potential lytic agent and to evaluate its lytic efficacy. Method; The AP solution was aseptically prepared by adding UK to autologous plasma separated by centrifugation (at 4 degrees C, 3,000 rpm, 10 min). The induced plasmin activity of the AP solution was measured by plasminogen-free fibrin plate method and spectrophotometric method with substrate S-2251. In vitro study, we made a fibrin clot by adding CaCl2 (1/40 mole, 0.2 ml) to autologous plasma (0.2 ml). The clot weight was measured before and after incubation for 60 min at 37 degrees C to estimate the lytic effects of the AP solution and the UK solution. In animal study, femoral artery of anesthetized mongrel dogs (n = 20) was narrowed by ligation (1 mm in diameter) and the fibrin clot was embolized into this portion. AP (n = 8), UK (n = 6) or saline (n = 6) was selectively injected for 3 min into the arterial lumen, after the temporary flow obstruction was completed by inflation of balloon tip catheter located proximal to the embolized site of the artery. Lytic effects on the embolized fibrin clot were sequentially observed by the extra-vascular ultrasound flow meter (equipped with pencil probe) for 60 min. For this study, the AP solution was prepared by adding dose of 12,000 IU/ml of UK. The same dose of the UK solution was also used as a control.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[The potential thrombolysis under selective infusion of the autologous plasmin (AP) solution]. 296 1

The effect of tissue plasminogen activator (TPA) or urokinase on the specific binding of human Glu-plasminogen to fibrin I formed in plasma by clotting with Reptilase was studied using 125I-plasminogen and 131I-fibrinogen. In the absence of TPA, small amounts of plasminogen were bound to fibrin I. TPA induced binding of plasminogen to plasma fibrin I that was dependent upon the concentrations of TPA and plasminogen as well as upon the time of incubation. Plasminogen binding occurred in association with fibrin clot lysis and the formation in the clot supernatant of alpha 2-plasmin inhibitor-plasmin complexes. Urokinase also induced binding of plasminogen to plasma fibrin I that was concentration- and time-dependent. The molecular form of plasminogen bound to the fibrin I plasma clot was identified as Glu-plasminogen by dodecyl sulfate-polyacrylamide gel electrophoresis and by fast performance liquid chromatography. Further studies demonstrated that fibrin I formed from fibrinogen that had been progressively degraded by plasmin-bound Glu-plasminogen. The mole ratio of plasminogen bound increased with the time of plasmin digestion. Glu-plasminogen did not bind to fibrin I formed from fibrinogen progressively digested by human leukocyte elastase, thereby demonstrating the specificity of plasmin. These studies demonstrate that plasminogen activators regulate the binding of Glu-plasminogen to fibrin I by catalyzing plasmin-mediated modifications in the fibrin substrate.
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PMID:Tissue plasminogen activator and urokinase mediate the binding of Glu-plasminogen to plasma fibrin I. Evidence for new binding sites in plasmin-degraded fibrin I. 315 57

Monoclonal antibodies against human plasminogen activator urokinase have been produced. A G62 hybridoma-producing antibody (IgG) was purified on a DEAE-cellulose column, and it proved useful for the measurement, identification and purification of antigens that had approximate molecular weights of 55- and 33-Kdaltons. For immunochemical measurements and purification, a competitive enzyme-linked immunosorbent assay (ELISA) and affinity chromatography using antibody-immobilized Sepharose 4B were developed. The ELISA has sensitivity to 20 p mole antigen molecules. The binding capacity of the antigen on the affinity column was evaluated on SDS-polyacrylamide slab gels as well as by fibrin autography and ELISA. Results showed that there was quantitative purification with no loss of enzyme activity in the one-step procedure. Western blotting and affinity binding showed antigenic bands with apparent molecular weights of 55- and 33-Kdaltons. Because the 55-Kdalton form contains 33- and 22-Kdalton components connected by a disulfide bond, the epitope domain is present on the 33-Kdalton chain. Using this antibody, we examined human kidney sections by direct immunofluorescence to locate the antigen. It was found in epithelial cells convoluted segments, in glomerulus cells and in capillary endothelial cells, evidence that renal tubular cells synthesize the antigen which then is secreted in urine.
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PMID:A monoclonal antibody against human urokinase: characterization of the epitope and its localization in human kidney. 620 21

The Tyr-SV40E transgenic mouse model of malignant skin melanoma has been used here to generate melanomas in genetically identical (C57BL/6) mice for analysis of the plasminogen activator (PA) system during tumor development and progression. Twenty-two melanocytic lesions were examined by in situ zymography for PA activity and by immunohistochemistry for concomitant visualization of PA proteins; these lesions encompassed 3 nevi and 19 primary melanomas ranging from melanotic through mixed tumors to amelanotic tumors. Although urokinase-type plasminogen activator (u-Pa) activity was not detected at premalignant stages, it began to appear early in tumorigenesis and became more prominent in later stages of a majority of the tumors. The activity was largely attributable to the endothelium of sprouting capillaries and to a lesser degree to granulocytes, fibroblastic cells, and occasional melanoma cells within tumors. Tissue-type plasminogen activator (t-PA) was undetectable or low in all cases. Of the inhibitors (PAI), PAI-1 was seen in endothelial and fibroblastic cells and in the extracellular matrix, whereas PAI-2 occurred in only one case and was melanoma cell associated. Eleven additional melanomas were analyzed by reverse transcription-PCR for PA expression in RNA extracts from relatively large tumor samples. These were obtained from eight primary melanomas and three metastases, again spanning melanotic, mixed, and amelanotic cases. From four of the mixed primary tumors with distinct melanotic and amelanotic zones, the respective components were propagated separately in transgenic hosts as s.c. transplants to obtain data for clearly identifiable melanotic versus amelanotic parts. u-PA and PAI-1 mRNAs were expressed in all. t-PA expression varied greatly and was notably high in several amelanotic tumors or tumor components, possibly as a result of large blood vessels, as such vessels were seen to be t-PA positive in normal tissue. The u-PA activity in sprouting capillaries may indicate a role in neoangiogenesis. Therefore, according to these mouse models, u-PA may indirectly be a potential therapeutic target against melanoma progression.
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PMID:Expression of plasminogen activators and plasminogen activator inhibitors in cutaneous melanomas of transgenic melanoma-susceptible mice. 755 49

Snake venoms, especially from the Crotalidae family, contain a variety of enzymes that prevent blood coagulation by virtue of their fibrinolytic enzymes. Nineteen snake venoms were screened for fibrinolytic activity and the highest activity was found in the venom of Crotalus basiliscus basiliscus venom. The active principle, basilase, was isolated, purified, and found to have fibrinolytic and fibrinogenolytic activity. It had a molecular weight of 22,000 and 1 mol of zinc per mole of protein associated with it. The proteolytic activity of the enzyme against dimethyl casein was inhibited by ethylenediaminetetraacetic acid and alpha 2-macroglobulin. It did not inactivate alpha 2-macroglobulin. Basilase did not have any of the following activities: thrombin-like, factor X-like, protein C activating, or urokinase-like. It caused neither hemorrhage nor platelet aggregation. In spite of its proteolytic activity, basilase did not hydrolyze the membranes of platelets. Basilase had 24% alpha-helix, 31% beta-sheet, 25% turns, and 20% unordered structure, as determined by Fourier Transform Infrared spectroscopy. Basilase is an enzyme that hydrolyzes fibrin directly without activation of plasminogen.
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PMID:Biochemical characterization of basilase, a fibrinolytic enzyme from Crotalus basiliscus basiliscus. 789 51

A large body of experimental evidence suggests that plasminogen activators provide tumoral cells with efficient means to degrade extracellular matrix constituents and thereby facilitate their dissemination to distant sites. Melanocytic neoplasia encompass a spectrum of lesions exhibiting diverse clinical behavior that remain difficult to predict with current histopathological evaluations. Little information concerning the contribution of plasminogen activation in diagnostic specimens of human melanocytic tumors is presently available. We thus analyzed biopsy specimens of pigmented skin lesions by histological techniques that identify the cellular sites of synthesis of plasminogen activators and of their inhibitors and that localize the sites of plasminogen activators-catalyzed enzymatic activities. We found that urokinase-type plasminogen activators (uPA) and plasminogen activator inhibitor type 1 mRNAs accumulate in atypical nevocytes and in melanoma cells, but not in benign nevocytes. However, uPA-catalyzed proteolytic activity was detected exclusively in melanomas. These observations suggest that up-regulation of the uPA gene is an early feature of melanocyte transformation and that unbalanced enzyme/inhibitor activity is associated with the malignant phenotype. By supporting a role for uPA in melanoma invasiveness, they provide a novel tool for the evaluation of atypia in nevi.
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PMID:Plasminogen activation in melanocytic neoplasia. 804 5


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