Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.68 (tissue plasminogen activator)
 11,311 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a pilot study on 9 patients with acute deep venous thrombosis of the leg the fibrinolytic response and the possible thrombolytic effect of desmopressin (DDAVP), when given supplementary to standard heparin treatment, was examined. Six injections of 0.3-0.4 microgram DDAVP/kg b.w. at 12 hours intervals were given. No serious side effects were observed. The fibrinolytic variables that followed showed that plasma levels of t-PA increased significantly and most pronounced after the first injection. Rephlebography 4-7 days after hospitalization showed partial thrombolysis in 7 out of 9 patients. The phlebographic score according to Marder was reduced from 22.7 +/- 12.1 to 18.4 +/- 10.1 (p = 0.018), corresponding to a thrombus size reduction of 19%. No correlation between the level of the fibrinolytic variables measured and the degree of thrombolysis in the individual patients, could be demonstrated in this small number of patients.
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PMID:A pilot study; desmopressin (DDAVP) in the treatment of deep venous thrombosis. 310 64

Some patients with von Willebrand's disease do not respond to stimuli such as venous occlusion and infusion of a vasopressin analogue DDAVP. In these patients, fibrinolytic activity is not enhanced and von Willebrand's factor is not released into the blood. Skin biopsies and cryostat sections were used to study the fibrinolytic activity of skin vessels and localization of tissue plasminogen activator (t-PA) in three patients with severe form of von Willebrand's disease. On fibrin films, no fibrinolysis developed around the skin vessels of the patients; however, using specific polyclonal and monoclonal antibodies to t-PA, and peroxidase coupled specific IgG, presence of t-PA antigen was demonstrated in endothelial cells (EC) of all of them. In plasma no t-PA activity was detected either before or after venous occlusion although t-PA inhibitor activity was in a normal range. Small amounts of t-PA antigen was measured in blood by ELISA. From these results, it is concluded that in patients with severe forms of von Willebrand's disease, t-PA present in EC is not functional and can not transform plasminogen into plasmin.
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PMID:Absence of functional activity of tissue plasminogen activator in patients with severe forms of von Willebrand's disease. 311 91

Reference values of tissue-type plasminogen activator (t-PA) antigen, t-PA activity, and plasminogen activator inhibitor (PAI) were established in healthy blood donors using different assay systems. Significant differences between male and female donors were found, due to the intake of oral contraceptives. PAI-activity determinations, using the method described by Chmielewska et al. (1983) or the modification by KabiVitrum, were only poorly correlated (r = 0.53; N = 98; p greater than 0.0001). PAI-activity (Chmielewska et al. 1983) determinations and t-PA antigen measurements were also significantly correlated (r = 0.52; N = 96), which may be a consequence of a joint regulation. In a second series, the diurnal variations of t-PA and PAI were investigated in blood donors (N = 83). PAI-activity and t-PA antigen were about 30 to 40 percent decreased in the evening hours, when compared with the morning values. In two controlled studies, the acute effects of heparins and desmopressin (DDAVP) on the fibrinolytic system were investigated in healthy individuals (N = 10). Again, a pronounced diurnal variation of t-PA and PAI was found. PAI and t-PA were significantly higher in the morning when compared with the evening. However, t-PA activity (Verheijen et al. 1982) showed a reversed pattern, low levels were found in the morning and increased levels in the evening. Our studies clearly show that when determining parameters of the fibrinolytic system, the diurnal variations have to be taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Problems in measuring parameters of the fibrinolytic system: circadian rhythm of tissue-type plasminogen activator and plasminogen activator inhibitor]. 312 47

Fibrinolysis dependent on the release of tissue plasminogen activator (t-PA) can only be explored after stimulation eliciting the release of t-PA from endothelial cells. The choice of the stimulus and test assay is of utmost importance in discriminating patients at risk for persistent thrombosis and in identifying acquired or genetic abnormalities of t-PA synthesis or release from endothelial cells in pathologic conditions. The present study was designed to compare the efficacy and reproducibility of the fibrinolytic response to desmopressin acetate (deamino-8-D-argininevasopressin) (DDAVP) by use of various routes of administration with the response to the venous occlusion test. Nine healthy male volunteers were randomly administered intravenous desmopressin acetate, intranasal drops and intranasal spray. The results from tests of euglobulin lysis time, t-PA activity, t-PA antigen levels, and t-PA fast-acting inhibitor (plasminogen activator inhibitor [PAI]) level were compared with those obtained after venous occlusion. The only test that elicited the release of free t-PA activity in the circulation in all volunteers was the intravenous administration of 0.4 microgram/kg desmopressin acetate, and the most reliable test assay was t-PA activity measured in the euglobulin fraction of plasma. Intravenous desmopressin acetate induced the release of large amounts of t-PA in most cases and caused a significant fall in PAI. Other routes of administration of desmopressin acetate, along with venous occlusion, identified many nonresponders who proved to be false negative. The relevance of these data was demonstrated in a study in nine patients with thromboembolic phenomenon or related disorders.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A dynamic test to investigate potential tissue plasminogen activator activity. Comparison of deamino-8-D-argininevasopressin with venous occlusion in normal subjects and patients. 313 70

The pharmacokinetics and haematological effects of 1-deamino-8-D-arginine vasopressin (desmopressin, DDAVP) after intravenous, subcutaneous and intranasal administration has been studied in man. Using a sensitive, specific radioimmunoassay for DDAVP, the AUC was determined for each route of administration. It was not significantly different for the i.v. and s.c. routes. There was no effect of the route on the plasma half-life of DDAVP which ranged from 2.7 to 4.6 h. Absorption of DDAVP after intranasal (i.n.) administration was poor. Based on AUC data, bioavailability via the two s.c. methods and the i.n. route was 112%, 94% and 2%, respectively. DDAVP has a pronounced effect on coagulation and fibrinolytic parameters, causing a 4.0- (i.v.), 2.9- (s.c.), 3.1- (s.c.; 40 micrograms/ml) and 1.2- (i.n.) fold increase in factor VIII: Ag. The corresponding effect on tissue-type plasminogen activator (t-PA) was 1.9- (i.v.), 1.3- (s.c.), 2.2- (s.c.; 40 micrograms/ml) and 1.0- (i.n.) increase over the basal value. There was also a 1.4- to 1.6-fold increase in leukocyte count 4 h after s.c. and i.v. DDAVP. At plasma DDAVP levels greater than 300 pg/ml no correlation was found between the AUC and the maximum plasma DDAVP and biological response, which indicates a ceiling limit for exogenous stimulation of the coagulation and fibrinolytic systems.
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PMID:Pharmacokinetics and haematological effects of desmopressin. 314 Nov 99

In eight male patients with normal liver and kidney function fibrinolytic components were measured in arterial blood and in renal and hepatic vein blood, obtained during catheterization for analysis of hypertension. Blood samples were collected simultaneously from veins und corresponding arteries before and 5 minutes after the completion of intravenous injection of desmopressin (DDAVP), 0.4 micrograms/kg body weight over a 10 minute period. DDAVP induced a rise in t-PA antigen and activity, and in von Willebrand factor, accompanied by a decrease in free PA-inhibitor level. We failed to detect a significant rise in plasma urokinase activity. The concentrations of fibrinogen, plasminogen, alpha 2-antiplasmin, antithrombin III and coeruloplasmin did not change either. Renal production of t-PA under basal conditions was inferred from a negative arterio-venous (A-V) difference in t-PA-activity and in t-PA-antigen levels but this could not be confirmed by orthogonal regression analysis of the same data. A-V differences of other fibrinolytic factors were negligible. In the hepatic vessels a significant positive A-V difference of t-PA-activity and of t-PA-antigen levels was a uniform finding. After DDAVP, when plasma levels were elevated, the mean A-V difference was proportionally higher, consistent with a constant fractional elimination rate. Free PA-inhibitor was virtually absent from arterial blood after DDAVP, but appeared in hepatic vein blood, indicating either production of the inhibitor by the liver or dissociation of a circulating complex of t-PA and its inhibitor in the liver. The blood levels of the other investigated components did not show any change upon passage through the liver.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renal and hepatic handling of endogenous tissue-type plasminogen activator (t-PA) and its inhibitor in man. 314 78

The aim of the study was to investigate the long-term chronic effects of smoking on the fibrinolytic enzyme system by comparing two groups of healthy male volunteers (aged 30 to 40 years). One group consisted of 15 habitual smokers who consumed 20 or more cigarettes a day; the other consisted of 15 nonsmokers. Fibrinolysis was studied at rest (baseline) and after infusion of 1-desamino-8-D-arginine vasopressin (DDAVP; 0.4 micrograms/kg body weight). Smokers had significantly lower baseline blood fibrinolytic activity as determined by the overall assays: dilute blood clot lysis (p less than or equal to 0.05) and euglobulin-fibrin plate assay (p less than or equal to 0.05). Further analysis showed that these low activities could be attributed to a lower baseline level of extrinsic tissue-type plasminogen activator (t-PA) activity (p less than or equal to 0.05) in the smokers. There were no significant differences between the groups in various fibrinolytic inhibitors or in the intrinsic fibrinolytic activation pathways. The increased levels of t-PA activity and factor VIII R:Ag in response to DDAVP were also reduced in the smokers (p less than or equal to 0.01). The relative increase (ratio of post-DDAVP activity/baseline activity) for these parameters was not significantly different for the two groups. Smokers also had significantly higher levels of the acute phase reactants, alpha 1-antitrypsin (p less than or equal to 0.02) and plasminogen (p less than or equal to 0.02) and C-reactive protein (p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of chronic smoking on fibrinolysis. 387 92

Fibrinolytic factors were measured before and after DDAVP-infusion in 18 patients on chronic, regular haemodialysis, 11 of whom underwent bilateral nephrectomy, and in 7 patients in whom non-functioning kidneys were still present. Baseline fibrinolytic activity was normal or high in all but two cases. Before haemodialysis, the response to DDAVP-infusion was greatly reduced in the majority of patients as compared with healthy controls, irrespective of the baseline level. This was in accordance with mean t-PA-antigen levels which increased only slightly after DDAVP. When DDAVP was given after haemodialysis, previous non-responders showed a normal increase in fibrinolytic activity. The level of free t-PA-inhibitors was normal in most cases as were levels of alpha 2-antiplasmin and alpha 2-macroglobulin.
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PMID:Fibrinolytic activators and inhibitors in terminal renal insufficiency and in anephric patients. 608 94

Patients with hyperlipoproteinaemia or spontaneous thromboembolism, known to be poor responders to DDAVP or to venous occlusion with regard to the rise in fibrinolytic activity of the blood, appeared to show a normal increase in t-PA-antigen after the same procedure. In their plasma a higher than normal level of free, fast-acting t-PA-inhibitor was found as measured by titration with purified t-PA. This free t-PA-inhibitor level only decreased after the test, in contrast to its complete disappearance in normal responders. The same happened in a healthy volunteer who failed to exhibit a rise in fibrinolytic activity after exhaustive exercise. We suppose that the lack of response of the fibrinolytic activity in these cases is due to a high inhibitor level and not to impaired release of t-PA into the blood. In contrast, patients with terminal renal insufficiency showed only a slight increase in t-PA-antigen after DDAVP. The level of free fast-acting inhibitor was normal in most cases and did not change appreciably during DDAVP-infusion. In these patients, a true impairment of the release of t-PA appears to exist.
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PMID:Masking of fibrinolytic response to stimulation by an inhibitor of tissue-type plasminogen activator in plasma. 644 2

The acute simultaneous release of tissue plasminogen activator (t-PA) and von Willebrand factor (vWF) from endothelial cells in response to a variety of agonists including thrombin, DDAVP, histamine and adrenalin has been described. In the present study we investigated the effect of venous occlusion on the circulating levels of t-PA and vWF, as well as the molecular organization of vWF in 20 normal subjects. After occlusion a significant increase in plasma t-PA levels was observed even after the values were corrected for haemoconcentration. Venous occlusion also enhanced plasma vWF values, but the increase was abolished when the correction for haemoconcentration was introduced. Following venous occlusion, no circulating abnormally large vWF multimers were detected in the subjects studied. These forms are normally not present in the circulation and are released from endothelial cells through the regulated vWF pathway; their absence therefore seems to demonstrate that this pathway is not activated after venous occlusion. Since occlusion does not enhance vWF synthesis, the increase in vWF observed in the subjects investigated may be fully attributed to haemoconcentration.
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PMID:Demonstration that venous occlusion fails to release von Willebrand factor multimers. 757 1


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