Nigral degeneration following striato-pallidal lesion in tissue type plasminogen activator deficient mice.

Tissue type plasminogen activator (tPA) has been suggested as a key factor in excitotoxic neuronal death in the hippocampus. Transneuronal degeneration of the substantia nigra pars reticulata (SNR) neurons after striato-pallidal lesions is attributable to excess excitatory glutamatergic inputs into the SNR following inhibitory GABAergic deafferentation and tPA may contribute to the mechanism of transneuronal degeneration of the SNR. To examine this possibility, we studied pathological changes in the SNR following striato-pallidal lesions produced by electrocoagulation in tPA-deficient mice. There was no difference in the degree of SNR degeneration, or in microglial activation and proliferation in the degenerating SNR of tPA-deficient and control mice. Our results indicate that tPA does not contribute to transneuronal degeneration in the SNR following striato-pallidal lesions in mice.     

Reduction in fibrotic tissue formation in mice genetically deficient in plasminogen activator inhibitor-1

Mice with homozygous deletion of the plasminogen activator inhibitor-1 gene (PAI-1(-/-)) are relatively protected from bleomycin-induced pulmonary fibrosis. At least part of the protective effect appears to occur during the latter stages of the pathological process when fibrotic tissue is being deposited. To investigate the effect of PAI-1 deficiency on fibrosis, we studied the accumulation of fibrotic tissue within subcutaneously implanted polyvinyl alcohol sponges. Similar to the effect of PAI-1 deficiency on bleomycin-induced pulmonary fibrosis, the accumulation of fibrotic tissue within implanted sponges occurred more slowly in PAI-1(-/-) compared to wild-type mice. Another striking difference observed in the PAI-1(-/-) mice was the rapid removal of a fibrin-rich matrix that formed within the sponges by 1 day after implantation in both wild-type and PAI-1(-/-) mice. The pattern of connective tissue invasion also differed: cells in wild-type mice infiltrated as individually penetrating cells whereas in PAI-1(-/-) mice they did so as a well-demarcated advancing front. Providing an alternative provisional matrix by impregnating sponges with a low concentration of collagen before implantation corrected the changes induced by PAI-1 deficiency. In conclusion, PAI-1 deficiency appears to affect fibrotic tissue formation in part by altering the provisional matrix that forms soon after tissue injury.     

Plasma tissue plasminogen activator and plasminogen activator inhibitor-1 levels in acute myocardial infarction

The cause of the circadian variation in the incidence of acute myocardial infarction (AMI) has not been identified. Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) have opposing effects on thrombi. Hence, the extent of the clot, the size of the infarct and outcome of patients could depend on t-PA and PAI-1 levels. In an effort to elucidate the pathophysiologic basis of circadian variation of AMI, we investigated the presence of a possible corresponding circadian variation in the levels of endogenous t-PA and PAI-1 in patients diagnosed to have AMI and the effects of hypertension, diabetes and site of the infarct on these levels. We estimated the levels of t-PA and PAI-1 in platelet-poor plasma of 42 patients with AMI on admission, using the enzyme-linked immunosorbant assay. Although not statistically significant, patients having an AMI in the morning hours had the highest t-PA:PAI-1 ratio. The normal circadian variation in PAI-1 levels was lost in patients with AMI, probably due to the disease process. Also, the t-PA levels in hypertensive patients were significantly lower than in nonhypertensives. PAI-1 levels were also significantly lower in patients with anteroseptal than in inferior and anterolateral AMI. This relationship between the fibrinolytic potential and the site of infarction needs further study. Furthermore, t-PA levels on admission were significantly lower in survivors and may have a predictive value in determining the outcome.     

Circadian fluctuations in plasma levels of tissue plasminogen activator antigen and plasminogen activator inhibitor activity

Daily fluctuations of t-PA antigen and PAM activity were measured in plasma samples of physically active young healthy volunteers (group 1, n = 11; age range 20–38 years) and compared to data obtained from resting patients (group 11, n = 23; age range 44–67 years) suffering from moderate valvular disease without evidence for inflammatory, neoplastic, or thrombosis-related diseases (e.g. deep vein thrombosis, coronary artery disease). t-PA antigen concentration showed a similar diurnal pattern in both study groups with the peak value at 06:00 but was significantly increased in the higher aged group at all collection times. PAM activity had its acrophase in both groups at or around 03:00 but no age-dependent differences could be demonstrated. t-PA antigen as well as PAI-1 activity fluctuations conserved their typical pattern despite differences in physical activity in the study groups.     

Relationship between tissue plasminogen activator,plasminogen activator inhibitor and CT image in chronic subdural hematoma.

The present study was performed to investigate the relationship between the concentrations of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) and the CT images in 23 cases of chronic subdural hematomas (SDHs). The concentrations of t-PA and PAI-1 were quantified by enzyme-linked immunosorbent assay (ELISA). Chronic SDHs were divided into five groups according to their appearance on computed tomography: high-density (n = 4), isodensity (n = 8), low-density (n = 5), mixed-density (n = 3), layering (n = 3) types. The volume of hematoma was measured with an image analyzing software program. The concentrations of t-PA were higher in layering (41.2 +/- 0.3 ng/ml, mean +/- standard error of the mean) and high-density (40.0 +/- 1.1 ng/ml) types compared to those of low-density (23.3 +/- 4.1 ng/ml) and iso-density (25.1 +/- 3.7 ng/ml) types. The concentrations of PAI-1 were lower in layering (95.9 +/- 1.0 ng/ml) and high-density (103.4 +/- 34.5 ng/ml) types compared to that of low-density (192.5 +/- 2.6 ng/ml) type. So the ratio between t-PA and PAI-1 (t-PA/PAI) was greater in layering and high-density types. The volume of hematoma was larger in mixed-density and layering types but statistically insignificant. These results presumably suggest that the ratio between t-PA and PAI concentration may contribute to the pathogenesis of the chronic SDH.     

Acute psychological stress decreases plasma tissue plasminogen activator (tPA) and tissue plasminogen activator/plasminogen activator inhibitor-1 (tPA/PAI-1) complexes in cardiac patients

Tissue plasminogen activator (tPA) promotes fibrinolysis, and impaired fibrinolysis is associated with atherosclerosis and thrombosis. Plasminogen activator inhibitor-1 (PAI-1) inhibits t-PA expression. The effects of acute laboratory stressors on tPA and tPA/PAI-1 complexes were assessed in a sample of 11 cardiac patients. Participants were randomly assigned to either a stress or relaxation condition at time 1, and the alternative condition at time 2. Blood samples were taken before (pre) and after (post) each session and participants completed a battery of psychological questionnaires. Two-way repeated-measures analysis of variance revealed a statistically significant decrease in tPA (P=0.01) and tPA-PAI-1 complexes (P=0.04) during the mental stress condition. Anger-in had a strong relationship to decreases in tPA/PAI-1 levels in the stress condition (r=0.68, P?<?0.05). Relaxation had no significant effect on tPA and tPA/PAI-1 levels. These data suggest that decreased fibrinolysis mediates the relationship between mental stress and atherosclerosis.     

Acute psychological stress decreases plasma tissue plasminogen activator (tPA) and tissue plasminogen activator/plasminogen activator inhibitor-1 (tPA/PAI-1) complexes in cardiac patients

Tissue plasminogen activator (tPA) promotes fibrinolysis, and impaired fibrinolysis is associated with atherosclerosis and thrombosis. Plasminogen activator inhibitor-1 (PAI-1) inhibits t-PA expression. The effects of acute laboratory stressors on tPA and tPA/PAI-1 complexes were assessed in a sample of 11 cardiac patients. Participants were randomly assigned to either a stress or relaxation condition at time 1, and the alternative condition at time 2. Blood samples were taken before (pre) and after (post) each session and participants completed a battery of psychological questionnaires. Two-way repeated-measures analysis of variance revealed a statistically significant decrease in tPA (P = 0.01) and tPA-PAI-1 complexes (P = 0.04) during the mental stress condition. Anger-in had a strong relationship to decreases in tPA/PAI-1 levels in the stress condition (r = 0.68, P < 0.05). Relaxation had no significant effect on tPA and tPA/PAI-1 levels. These data suggest that decreased fibrinolysis mediates the relationship between mental stress and atherosclerosis.     

Autoantibodies to plasminogen and tissue plasminogen activator in women with recurrent pregnancy loss

Reduced fibrinolytic activity has been described in primary anti-phospholipid syndrome (PAPS), and may be responsible for thrombotic events. Antibodies to tissue type plasminogen activator (t-PA) or plasminogen (PLG) might contribute to the hypofibrinolytic state in autoimmune diseases, but the clinical significance of these antibodies is still unclear in recurrent pregnancy loss (RPL). The aim of this study is to evaluate the prevalence and clinical significance of anti-PLG and anti-t-PA antibodies in 87 patients with a history of RPL: 54 women with well-defined PAPS (mean age 32.5 years; range 26-38) and 33 women with unexplained RPL (mean age 30 years; range 24-39). IgG anti-PLG antibodies were found in 20 and four patients from the group with RPL/PAPS and unexplained RPL, respectively; IgG anti-t-PA antibodies were found in 11 and two patients from the above two groups, respectively. IgG anti-PLG antibodies were associated with the high risk of RPL (OR 7.2, P = 0.004), especially with RPL/PAPS (OR 11.2, P < 0.001) evaluated by Fisher's exact test, while IgG anti-t-PA were associated with RPL/PAPS (OR 10.0, P = 0.01) but not with RPL (OR 6.8, P = 0.06). A significant inhibition of exogenous fibrinolysis was observed by IgG fractions from patients with anti-PLG or anti-t-PA antibodies on microplates and on the human umbilical vein endothelial cells, compared with those from healthy controls. The prevalence of IgG anti-PLG antibodies was high in RPL patients, especially in RPL/PAPS, while the prevalence of IgG anti-t-PA antibodies was high in RPL/PAPS but not in RPL, and some of them might inhibit fibrinolysis in patients.     

Arrhenius temperature dependence of in vitro tissue plasminogen activator thrombolysis

Stroke is a devastating disease and a leading cause of death and disability. Currently, the only FDA approved therapy for acute ischemic stroke is the intravenous administration of the thrombolytic medication, recombinant tissue plasminogen activator (tPA). However, this treatment has many contraindications and can have dangerous side effects such as intra-cerebral hemorrhage. These treatment limitations have led to much interest in potential adjunctive therapies, such as therapeutic hypothermia (T 相似文献   

A simple quantitative assay of tissue plasminogen activator.

A simple method for the quantitative assay of tissue plasminogen activator is described. Human veins and uterus obtained at operation are disintegrated in a membrane disintegrator at -70 degrees C and a known weight of the powder, suspended in buffered saline and thoroughly mixed. Assay of the dilutions of this homogenate on isotope-labelled fibrin clots gives straight line plots of log weight against log activity of the dilution and the sample activity is calculated from this. The method has been compared with the conventional histochemical technique. A highly significant correlation between the results of the two methods has been obtained (r = 0.79; p less than 0.001).     

Oxidative stress, plasminogen activator inhibitor 1, and lung fibrosis

Fibrosis is characterized by excessive accumulation of extracellular matrix (ECM) in basement membranes and interstitial tissues, resulting from increased synthesis or decreased degradation of ECM or both. The plasminogen activator/plasmin system plays an important role in ECM degradation, whereas the plasminogen activator inhibitor 1 (PAI-1) is a physiologic inhibitor of plasminogen activators. PAI-1 expression is increased in the lung fibrotic diseases and in experimental fibrosis models. The deletion of the PAI-1 gene reduces, whereas the overexpression of PAI-1 enhances, the susceptibility of animals to lung fibrosis induced by different stimuli, indicating an important role of PAI-1 in the development of lung fibrosis. Many growth factors, including transforming growth factor beta (TGF-beta) and tumor necrosis factor alpha (TNF-alpha), as well as other chemicals/agents, induce PAI-1 expression in cultured cells and in vivo. Reactive oxygen and nitrogen species (ROS/RNS) have been shown to mediate the induction of PAI-1 by many of these stimuli. This review summarizes some recent findings that help us to understand the role of PAI-1 in the development of lung fibrosis and ROS/RNS in the regulation of PAI-1 expression during fibrogenesis.     

Tissue plasminogen activator and urokinase plasminogen activator in human epileptogenic pathologies

A growing body of evidence demonstrates the involvement of plasminogen activators (PAs) in a number of physiologic and pathologic events in the CNS. Induction of both tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) has been observed in different experimental models of epilepsy and tPA has been implicated in the mechanisms underlying seizure activity. We investigated the expression and the cellular distribution of tPA and uPA in several epileptogenic pathologies, including hippocampal sclerosis (HS; n=6), and developmental glioneuronal lesions, such as focal cortical dysplasia (FCD, n=6), cortical tubers in patients with the tuberous sclerosis complex (TSC; n=6) and in gangliogliomas (GG; n=6), using immuno-cytochemical, western blot and real-time quantitative PCR analysis. TPA and uPA immunostaining showed increased expression within the epileptogenic lesions compared to control specimens in both glial and neuronal cells (hippocampal neurons in HS and dysplastic neurons in FCD, TSC and GG specimens). Confocal laser scanning microscopy confirmed expression of both proteins in astrocytes and microglia, as well as in microvascular endothelium. Immunoblot demonstrated also up-regulation of the uPA receptor (uPAR; P<0.05). Increased expression of tPA, uPA, uPAR and tissue PA inhibitor type mRNA levels was also detected by PCR analysis in different epileptogenic pathologies (P<0.05). Our data support the role of PA system components in different human focal epileptogenic pathologies, which may critically influence neuronal activity, inflammatory response, as well as contributing to the complex remodeling of the neuronal networks occurring in epileptogenic lesions.