Amounts Of Tissue Plasminogen Activator Research Articles

Short-Term Complications and Outcomes in Pharmaco-Mechanical Thrombolysis First and Catheter-Directed Thrombolysis First in Patients with Acute Lower Limb Ischemia

Pharmaco-mechanical thrombolysis (PMT) has emerged as a treatment option in patients with acute lower limb ischemia (ALI), especially Rutherford IIb (motor deficit) for rapid revascularization, but supportive data is scarce. The aim of the present study was to compare the effects of thrombolysis, complications, and outcomes of PMT first versus catheter-directed thrombolysis (CDT) first in a large cohort of patients with ALI. All endovascular thrombolytic/thrombectomy events in patients with ALI performed between January 1st, 2009, and December 31st, 2018 (n=347) were included. Successful thrombolysis/thrombectomy was defined as complete or partial lysis. Reasons for using PMT were described. Complications such as major bleeding, distal embolization, and new onset of renal impairment, and major amputation and mortality at 30days were compared between PMT (AngioJet) first and CDT first groups in a multivariable logistic regression model with adjustment for age, gender, atrial fibrillation, and Rutherford IIb. The most common reason for initial use of PMT was the need for rapid revascularization, and the most common reason for use of PMT after CDT was the insufficient effect of CDT. Presentation of Rutherford IIb ALI was more common in the PMT first group (36.2% vs. 22.5%, respectively, P=0.027). Among the 58 patients receiving PMT first, 36 (62.1%) were terminated within a single session of therapy without need of CDT. The median duration of thrombolysis was shorter (P<0.001) for the PMT first group (n=58) compared to the CDT first group (n=289) (4.0hr vs. 23.0hr, respectively). There was no significant difference in amount of tissue plasminogen activator given, successful thrombolysis/thrombectomy (86.2% and 84.8%), major bleeding (15.5% and 18.7%), distal embolization (25.9% and 16.6%), major amputation or mortality at 30-days (13.8% and 7.7%) in the PMT first compared to the CDT first group, respectively. The proportion of new onset of renal impairment was higher in the PMT first compared to the CDT first group (10.3% vs. 3.8%, respectively), and the increased odds (odds ratio 3.57, 95% confidence interval 1.22-10.41) were maintained in the adjusted model. In Rutherford IIb ALI, no difference in rate of successful thrombolysis/thrombectomy (76.2% and 73.8%), complications or 30-day outcomes was found between PMT first (n=21) and CDT (n=65) first group. PMT first appears to be a good treatment alternative to CDT in patients with ALI, including Rutherford IIb. The found renal function deterioration in the PMT first group needs to be evaluated in a prospective, preferably randomized trial.

Use of Tissue Plasminogen Activator in Liver Transplantation from Donation After Cardiac Death Donors

Ischemic-type biliary stricture (ITBS) occurs in up to 50% after liver transplantation (LT) from donation after cardiac death (DCD) donors. Thrombus formation in the peribiliary microcirculation is a postulated mechanism. The aim was to describe our experience of tissue plasminogen activator (TPA) administration in DCD-LT. TPA was injected into the donor hepatic artery on the backtable (n = 22). Two recipients developed ITBS including one graft failure. Although excessive postreperfusion bleeding was seen in 14 recipients, the amount of TPA was comparable between those with and without excessive bleeding (6.4 ± 2.8 vs. 6.6 ± 2.8 mg, p = 0.78). However, donor age (41 ± 12 vs. 29 ± 9 years, p = 0.02), donor BMI (26.3 ± 5.5 vs. 21.7 ± 3.6 kg/m(2) , p = 0.03), previous laparotomy (50% vs. 0%, p = 0.02) and lactate after portal reperfusion (6.3 ± 4.6 vs. 2.8 ± 0.9 mmol/L, p = 0.005) were significantly greater in recipients with excessive bleeding. In conclusion, the use of TPA may lower the risk of ITBS-related graft failure in DCD-LT. Excessive bleeding may be related to poor graft quality and previous laparotomy rather than the amount of TPA. Further studies are needed in larger population.

Regulation of calcium to tissue plasminogen activator secretion in mouse epidermal keratinocytes

The amounts of tissue plasminogen activator (tPA) of culture supernatants, cell surfaces as well as intracellular spaces of the mouse keratinocytes cultured in calcium-free medium or in the presence of low or high calcium concentration medium were tested using enzyme-linked immunosorbent assay (ELISA). The results indicated that cultured keratinocytes could secrete tPA into extracellular space and respond to the addition of high calcium concentration with a time-dependent increase of tPA secretion, and the peak value of tPA secretion appeared after 24 h of keratinocytes culture. Furthermore, comparing the amount of tPA in culture supernatants with that in cell surfaces, it was found that after culture for 24 h, the secreted tPA could bind to the surfaces of the keratinocytes through the lysine sites within its molecule, and this process was enhanced by high calcium concentration. On the basis of these data we assumed that in mouse keratinocytes, tPA firstly secretes into extracellular space and then binds to the keratinocytes surface, and calcium regulates tPA secretion and its following binding to the surface of keratinocytes, which may correlate with the differentiation of keratinocytes.

Increased Proteolytic Activity of the Granule Neurons May Contribute to Neuronal Death in the Weaver Mouse Cerebellum

The weaver mouse mutation is a genetic defect of unknown origin that leads to impairment of cerebellar granule neuronal migration and to neuronal cell death. We investigated laminin expression and proteolytic enzyme activity in this migration-deficient mouse mutant in vivo and in vitro to search for a molecular basis for the weaver defect. The weaver cerebellum showed a general increase in immunoreactivity for laminin, for a neurite outgrowth domain of the B2 chain of laminin, and for tissue plasminogen activator compared to the normal animals. Zymographic assays and immunocytochemistry confirmed that tissue plasminogen activator was the proteolytic enzyme synthesized in excess in the weaver mouse cerebellum in vivo. When placed in culture, the weaver granule neurons survived poorly on a laminin substratum, and failed to extend long neurites, unlike the normal cerebellar granule neurons. The cultured weaver granule neurons were proteolytically overactive and secreted excessive amounts of tissue plasminogen activator, which was likely to interfere with their neurite outgrowth potential on a laminin substratum. Indeed, the weaver granule neurons but not the normal neurons degraded laminin from their culture substratum and deposited a neurite outgrowth domain of the B2 chain of laminin onto their surfaces. Electrophysiology showed that the weaver granule neurons had poor resting membrane potentials (-38 V), whereas the normal neurons had normal resting membrane potentials of (-61 V). The resting membrane potentials of the weaver granule neurons were restored to near normal (-59 V) by a protease inhibitor, aprotinin. Aprotinin also rescued the weaver granule neurons from death on a laminin substratum and promoted their neurite outgrowth to the level of the normal animals. These results indicate that increased proteolytic activity accompanied with increased synthesis of laminin, and its B2 chain, distinguish the weaver mutation from the normal animals. These molecular changes may contribute to the impairment of granule neuronal migration and to the neuronal death, characteristic of the weaver mutation.

Transduced endothelial cells expressing high levels of tissue plasminogen activator have an unaltered phenotype in vitro

Elevated cellular plasminogen activator activity has been associated with significant alterations in the in vitro phenotype of both malignant cell lines and nonmalignant endothelial cells. To examine the role of elevated cellular plasminogen activator activity in the production of altered endothelial cell behavior, bovine coronary artery endothelial cells were transduced with a retroviral vector expressing large amounts of tissue plasminogen activator. Cells transduced with the tissue plasminogen activator vector were compared with both untransduced cells and cells transduced with a control vector in a series of in vitro assays of cellular attachment, proliferation, migration, and invasion. The morphology of the 2 transduced populations was unchanged. There was a small decrease (5-15%) in the horizontal migration rate of both transduced cell populations, as compared with that of untransduced cells. No significant differences were detected among the three cell populations in any of the other assays. We conclude that expression of high levels of tissue plasminogen activator does not specifically affect endothelial cell phenotype in vitro. These data lend support to the hypothesis that elevated plasminogen activator activity is necessary but not sufficient to produce alterations in endothelial cell behavior.

Bimodal relationship between invasion of the amniotic membrane and plasminogen activator activity

Three human tumor cell lines, Bowes' melanoma, HT1080 and Osmond cells, were characterized for their ability to invade the amniotic membrane and their production of plasminogen activator. Bowes' melanoma cells, which release large amounts of tissue plasminogen activator (tPA), were poorly invasive on the amniotic membrane. The addition of plasmin inhibitors, anti-tPA antibody or tissue inhibitor of metalloproteinase (TIMP) to the amnion assay enhanced invasiveness. The depletion of plasminogen from the growth medium also enhanced the degree of invasiveness. Similarly, HT1080 cells, which produce high levels of urokinase-type plasminogen activator (uPA), were poorly invasive under standard conditions but invasion was enhanced by plasmin inhibitors or anti-uPA antibodies. Conversely, Osmond cells, which produce low levels of uPA, were very invasive on the amniotic membrane. Invasion by these cells was blocked by the addition of plasmin inhibitors or anti-uPA antibodies to the amnion assay. These results suggest that invasion requires only a minimum level of PA activity and that, as PA production exceeds this optimal level, the degree of invasion decreases. We propose that high levels of plasmin, generated by the tPA or uPA secreted by the cells, may cause uncontrolled matrix degradation and interrupt the interaction of cells and matrix in the early stages of invasion. The inhibition of excessive plasmin activity may stabilize and increase cell matrix contacts and result in an enhancement of invasion.

Tissue Plasminogen Activator in Human Aqueous Humor and Its Possible Therapeutic Significance

By using an enzyme-linked immunosorbent assay, we detected a significant amount of tissue plasminogen activator (0.8 +/- 0.17 ng/ml) in the aqueous humor of ten normal human eyes. It was also identified on Western blot analysis. The ratio of tissue plasminogen activator to total protein in aqueous humor was about 30 times greater than the ratio of tissue plasminogen activator to total protein in plasma. There was evidence that at least some of the tissue plasminogen activator in the aqueous humor was synthesized locally by the structures bordering the anterior chamber of the eye. Tissue plasminogen activator may be a useful therapeutic modality in clinical conditions of delayed dissolution of fibrin in the eye.

Role of Enzymes Mediating Thrombosis and Thrombolysis in Lung Disease

Enzymes of the blood coagulation and fibrinolytic cascades are prominent in both the vascular and alveolar compartments of the human lung. Important differences exist in the regulation of these enzyme activities between the vascular and the alveolar compartments, suggesting different functions of similar enzymes in the two compartments. In the vascular bed, endothelial cells provide a nonthrombogenic lining layer and release small amounts of tissue plasminogen activator into the circulation, maintaining patency of the vascular bed, whereas the alveolar epithelial surface is replete with active enzymes of the extrinsic pathway of coagulation as well as urokinase. The alveolar surface seems primed to localize and degrade any fibrin that has leaked into alveoli during hemorrhagic states. In addition, parenchymal lung cells such as resident macrophages are coated with urokinase, providing a mechanism for cellular migration and ongoing extracellular matrix metabolism. Amplification of the PA/plasmin system in the lung during chronic inflammation, eg, cigarette smoking, could accelerate connective tissue breakdown. Recent evidence indicates that in acute inflammation there is an enhancement of mediators of coagulation and suppression of fibrinolysis. These observations may partly explain prior pathologic observations regarding the deposition of hyaline membranes and persistence of alveolar fibrin/fibronectin deposits that may be stimulants for alveolar fibrosis. The assembly of clotting components on the surface of macrophages and the integral involvement of macrophages with fibrin deposits in the lung are likely mechanisms for macrophage immobilization and focal accumulation important to local clearance, host defense, effective chemotactic signalling, and possibly proliferation since thrombin has mitogenic properties for other lung cells. Newer methods focusing on the biology and biochemistry of the pulmonary architecture and its cellular components should further elucidate the importance of these pathways and suggest new therapeutic options.