Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.7 (plasmin)
9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A two stage method for determination of plasminogen activator inhibitor (PAI) activity in blood plasma is described. In the first stage, an excess of single-chain tissue plasminogen activator (t-PA) is added to plasma. In the second stage, the residual t-PA activity is determined with a plasminogen/chromogenic plasmin substrate assay utilizing poly-D-lysine as a t-PA stimulator. The method proved accurate since it correctly determined the PAI activity (range 0 to 110U/mL) in citrated plasma samples with levels established by time course analysis of t-PA inhibition and by titration with t-PA. Furthermore, correlation was excellent (r = 0.97) with the method of Chmielewska et al Thromb. Res. 31, 427-436, 1983. Plasma samples with increased platelet factor 4, indicative of platelet release, did not show increased levels of PAI activity.
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PMID:Determination of plasminogen activator inhibitor in plasma using t-PA and a chromogenic single-point poly-D-lysine stimulated assay. 313 38

A murine monoclonal antibody (anti-C2G7), reactive with fibrinogen, was used to analyse the structure and function of the fibrinogen epitope C2G7. Anti-C2G7 was found to be reactive with fibrinogen but not with fibronectin, Factor VIII-von Willebrand Factor (FVIII-vWF), beta-thromboglobulin (beta TG), platelet factor 4 (PF4) nor with a range of normal cells and cell lines. Biochemical and plasmin digestion studies of fibrinogen revealed that C2G7 is present on the carboxy-terminal end of the alpha chain on a fragment with a Mr approximately 30-40 K. Functional studies, on the role of fibrinogen in coagulation and platelet function, demonstrated the importance of C2G7 (or a closely associated region) for thrombin-associated fibrin polymerization and collagen induced fibrinogen binding to platelets.
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PMID:Role of A alpha chain of fibrinogen in coagulation and platelet interaction investigated with a monoclonal antibody. 331 Mar 25

Low-affinity platelet factor 4 and beta-thromboglobulin are platelet-secreted proteins that bind with low affinity to heparin. They show extensive immunological cross-reactivity and appear to differ in amino acid sequence only by an amino-terminal peptide unique to low-affinity platelet factor 4. The possibility that beta-thromboglobulin is derived from low-affinity platelet factor 4 by proteolysis was investigated by exposing this protein to the action of plasmin, thrombin and trypsin. While thrombin had no effect, plasmin and trypsin converted low-affinity platelet factor 4 to a species with the same electrophoretic mobility and isoelectric point as beta-thromboglobulin. We conclude that beta-thromboglobulin is a breakdown product of low-affinity platelet factor 4.
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PMID:Conversion of low-affinity platelet factor 4 to beta-thromboglobulin by plasmin and trypsin. 615 45

The concentrations in plasma of fibrinogen derivatives fibrinopeptide A (FPA), beta 15-42 antigen and fragment E (FgE) antigen have been determined in patients with renal failure and compared to the concentrations of the platelet release products, beta-thromboglobulin (beta TG) and platelet factor 4 (PF4). In 'partial renal failure' (51Cr-EDTA clearance rate 4-60 ml/min) FPA, beta 15-42 antigen, FgE antigen and beta TG levels were significantly raised above a normal laboratory control group. These levels were further raised in a group of patients whose disease required regular maintenance haemodialysis (51Cr-EDTA clearance rate less than 4 ml/min). PF4 levels were not significantly raised in either group. A statistical analysis of all patient results revealed that FPA, beta 15-42 antigen and FgE antigen levels all correlated with beta TG levels but not with PF4 levels. It is known that beta TG is catabolized by the kidney but PF4 is not and that elevated beta TG levels in renal failure are caused by impaired elimination rather than increased production. These results suggest that the plasma levels of these three fibrinogen derivatives are elevated in renal disease at least in part by decreased elimination rather than by increased thrombin and plasmin activities alone.
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PMID:The significance of fibrinogen derivatives in plasma in human renal failure. 622 69

Serial measurements of the plasma concentration of fibrinopeptide A, thrombin-increasable fibrinopeptide B (reflecting B beta 1-42), desarginyl fibrinopeptide B, beta thromboglobulin, and platelet factor 4 were made before, during, and after delivery in patients with preeclampsia/eclampsia. The data were correlated with routine coagulation studies, hematologic and renal status, as well as with the clinical manifestations. In 11 patients with mild preeclampsia, there were small increases in the fibrinopeptides at the time of delivery, but no other hematologic changes. In 5 patients with severe preeclampsia/eclampsia, there were marked increases in plasma levels of fibrinopeptides and platelet alpha granule proteins, which correlated in time with the clinical manifestations. When the changes in these patients were compared with those occurring in patients undergoing intraamniotic hypertonic saline infusion, it was noted that: (1) patients with severe preeclampsia/eclampsia usually presented when plasmin action on fibrinogen exceeded that of thrombin; (2) in patients with preeclampsia/eclampsia the increase in fibrinopeptides lasted from 3 to 7 days, rather than for several hours as occurred after the infusion of hypertonic saline, indicating a more persistent stimulus to intravascular coagulation in preeclampsia/eclampsia; (3) severe thrombocytopenia and increased platelet protein levels were seen in these patients and were disproportionate to the degree of increase in the fibrinopeptide A level, suggesting that a mechanism other than thrombin must have contributed to the platelet changes; and (4) in two patients with severe preeclampsia/eclampsia, high desarginyl fibrinopeptide B levels preceded renal insufficiency, possibly reflecting fibrin II formation in renal vessels.
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PMID:Fibrinogen proteolysis and platelet alpha-granule release in preeclampsia/eclampsia. 623 Jan 18

The hypothesis that exercise-induced myocardial ischemia is associated with abnormal platelet activation and fibrin formation or dissolution was tested in patients with coronary artery disease undergoing upright bicycle stress testing. In vivo platelet activation was assessed by radioimmunoassay of platelet factor 4, beta-thrombo-globulin and thromboxane B2. In vivo fibrin formation was assessed by radioimmunoassay of fibrinopeptide A, and fibrinolysis was assessed by radioimmunoassay of thrombin-increasable fibrinopeptide B which reflects plasmin cleavage of fibrin I. Peripheral venous concentrations of these substances were measured in 10 normal subjects and 13 patients with coronary artery disease at rest and during symptom-limited peak exercise. Platelet factor 4, beta-thromboglobulin and thromboxane B2 concentrations were correlated with rest and exercise catecholamine concentrations to determine if exercise-induced elevation of norepinephrine and epinephrine enhances platelet activation. Left ventricular end-diastolic and end-systolic volumes, ejection fraction and segmental wall motion were measured at rest and during peak exercise by first pass radionuclide angiography. All patients with coronary artery disease had documented exercise-induced myocardial ischemia manifested by angina pectoris, ischemic electrocardiographic changes, left ventricular segmental dyssynergy and a reduction in ejection fraction. Rest and peak exercise plasma concentrations were not significantly different for platelet factor 4, beta-thromboglobulin, thromboxane B2, fibrinopeptide A and thrombin-increasable fibrinopeptide B. Peripheral venous concentrations of norepinephrine and epinephrine increased significantly (p less than 0.001) in both groups of patients. The elevated catecholamine levels did not lead to detectable platelet activation. This study demonstrates that enhanced platelet activation, thromboxane release and fibrin formation or dissolution are not detectable in peripheral venous blood of patients with coronary disease during exercise-induced myocardial ischemia.
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PMID:Exercise-induced myocardial ischemia in patients with coronary artery disease: lack of evidence for platelet activation or fibrin formation in peripheral venous blood. 633 91

Ulcerative colitis and Crohn's disease are associated with a high risk of thromboembolic complications. The questions whether reported risk factors such as low antithrombin III concentrations, thrombocytosis and spontaneous platelet aggregation are merely related to the activity of the inflammatory process remains to be answered. Therefore we investigated 40 patients with an established colitis or Crohn's disease, without signs of active inflammation (normal history, normal ESR and leucocyte count). Of these patients only one patient revealed thrombocytosis, six patients spontaneous platelet aggregation. All patients had normal beta-thromboglobulin and platelet factor 4 plasma levels. No other prethrombotic abnormalities were encountered. There was normal factor VIII C (increased in three patients), normal VIII C/VIII R Ag ratio (1.2), antithrombin III, normal plasminogen and normal alpha 2-antiplasmin. Normal fibrinopeptide A and B beta (15-42) plasma levels (n = 15) in these patients excluded in vivo thrombin or plasmin generation. We conclude that stable chronic inflammatory bowel disease is in general not associated with prethrombotic coagulation abnormalities.
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PMID:No evidence for a prethrombotic state in stable chronic inflammatory bowel disease. 665 71

There are many reports in the literature of blood test abnormalities occurring in patients with venous or arterial thrombosis. Most of these have not used acceptable criteria for establishing an association between thrombosis and blood tests and, therefore, their interpretation is questionable. Recently, sensitive and specific assays have been developed for the detection of products of intravascular thrombin formation, of plasmin digests of fibrin or fibrinogen and of platelet specific proteins that are released into the plasma when platelets react with stimuli. Blood abnormalities have been sought that can either predict or detect venous thrombosis. Many of the predictive tests evaluated are nonspecific acute phase reactant responses to inflammation; of these, only reduced fibrinolytic activity has been consistently reported to be associated with postoperative venous thrombosis. Hereditary antithrombin III deficiency has been consistently shown to predispose patients to venous thrombosis. Abnormalities of the plasminogen and fibrinogen molecule have also been described in patients with familial or recurrent venous thrombosis but these are rare and the association could be coincidental. Two blood tests, the fibrinopeptide A assay and the assay for fibrin/fibrinogen fragment E are highly sensitive to acute venous thromboembolism in symptomatic patients but both are nonspecific. Elevated levels of beta thromboglobulin and platelet factor 4 have been reported in patients with arterial thromboembolism but the sensitivity and specificity of these findings is presently unknown.
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PMID:Blood tests for the diagnosis of venous and arterial thrombosis. 700 30

An antigen immunochemically indistinguishable from plasma alpha 2-antiplasmin, the primary plasmin inhibitor, was detected in human platelets. By radioimmunoassay, 33-114 ng alpha 2-antiplasmin antigen was quantitated in the detergent-soluble extract of 10(9) washed human platelets from 10 normal donors with a mean level of 62 +/- 24 ng/10(9) platelets. Plasma alpha 2-antiplasmin, either in the platelet suspending medium or on the surface of the platelets, could account for less than 8% of the antigen present in the platelet extracts. When stimulated with thrombin, the platelets released alpha 2-antiplasmin antigen without cell lysis, and greater than 85% of the alpha 2-antiplasmin antigen was released at a high thrombin dose. At a lower dose of thrombin, alpha 2-antiplasmin and platelet factor 4 were partially released without concomitant secretion of serotonin. No alpha 2-antiplasmin antigen was detected in extracts or red blood cells, polymorphonuclear leukocytes, and adherent and nonadherent mononuclear cells. Thus, the platelet is the only peripheral blood cell containing significant amounts of alpha 2-antiplasmin.
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PMID:The presence and release of alpha 2-antiplasmin from human platelets. 730 99

To elucidate the relationship between glomerular deposition of plasmin-alpha 2-plasmin inhibitor complexes (PIC) and renal lesions or dysfunction, 25 patients with various glomerulopathies and various degrees of renal injuries were examined. Glomerular PIC deposition was found in eight patients (group A), and other 17 patients showed no deposition (group B). PIC was found mainly in the mesangium and along the capillary loops. Group A showed significantly more severe hematuria (p < 0.05) than group B. Group A showed a significant decrease in glomerular filtration rate (GFR; p < 0.05): the mean values being 60.8 +/- 39 in group A and 94.5 +/- 32 ml/min in group B. Group A showed a significant decrease in the phenolsulfonphthalein excretion test (p < 0.05). There was no significant difference in the mean values of plasma PIC, D-dimer, and thrombin-antithrombin III complexes (TAT) between two groups. Histologically, group A showed a significantly high incidence of adhesion (p < 0.05), crescentic formation (p < 0.05), endothelial swelling and/or detachment (p < 0.01), tubulointerstitial changes (p < 0.01), and glomerular deposition of platelet factor 4 (p < 0.01). The present study demonstrates that glomerular PIC deposition reflects the existence of activation of coagulation and fibrinolysis within the glomeruli and suggests that glomerular PIC deposition plays a part in the progression of renal injuries in various glomerulopathies.
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PMID:Significance of glomerular deposition of plasmin-alpha 2-plasmin inhibitor complexes in various glomerulopathies. 750 40


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