Development of a new test for the global fibrinolytic capacity in whole blood

Background: The development of global tests for the fibrinolytic capacity in blood is hampered by the low base-line fibrinolytic activity in blood, by the involvement of both plasmatic components and blood cells in the fibrinolytic system and by the loss of fibrinolytic activity as a result of the action of plasminogen activator inhibitor-1 (PAI...

Oral, but not transdermal, administration of estrogens lowers tissue- type plasminogen activator levels in humans without affecting endothelial synthesis

Oral estrogen administration decreases plasma levels of tissue-type plasminogen activator (tPA), which may be explained by a decrease in endothelial tPA synthesis, an increase in its hepatic clearance, or both. In the present study, we determined (1) differences between oral (ie, via the liver) ethinyl estradiol and transdermal (ie, systemic)...

Involvement of calcium and G proteins in the acute release of tissue- type plasminogen activator and von Willebrand factor from cultured human endothelial cells

In this study, we investigated the role of Ca2+ and G proteins in thrombin-induced acute release (regulated secretion) of tissue-type plasminogen activator (TPA) and yon Willebrand factor (vWF), using a previously described system of primary human umbilical vein endothelial cells (HUVECs). The acute release of TPA and vWF, as induced by α...

Interindividual and intraindividual variability in plasma fibrinogen, TPA antigen, PAI activity, and CRP in healthy, young volunteers and patients with angina pectoris

We compared intraindividual and interindividual variability in the plasma levels of fibrinogen, tissue-type plasminogen activator (TPA) antigen, plasminogen activator inhibitor (PAI) activity, and C-reactive protein (CRP) in 20 healthy, young individuals and 26 patients with stable angina pectoris (AP) who were at higher risk for cardiovascular...

Different effects of lipopolysaccharide on plasminogen activator inhibitor-1 production in aortic media in vivo and in culture

Background: Lipopolysaccharide (endotoxin) has been shown to increase the expression of plasminogen activator inhibitor type-1 (PAI-1) in the vessel wall. Endotoxin is known to increase PAI-1 production in endothelial cells, but its action on smooth muscle cells (SMCs) is presently not clear. In this study we determined the effect of endotoxin...

Interaction of reteplase with heparin. A comparison between reteplase and alteplase

Reteplase is a protein consisting of the kringle-2 and protease domains of tissue-type plasminogen activator (t-PA). Because intravenous heparin will be used as an adjunct to thrombolytic therapy with reteplase, we investigated the interactions in vitro between heparin and reteplase as well as between heparin and recombinant t-PA (alteplase) as...

Acute release of tissue-type plasminogen activator (t-PA) from the endothelium ; regulatory mechanisms and therapeutic target

The acute release of t-PA was studied in vitro in human endothelial cells from different origin. It proved possible to enhance the amounts of t-PA which can be released by increasing t-PA synthesis, both in vitro, and in vivo in rats. These data suggest the feasibility to induce and (or) enhance acute release of t-PA in man. Chemicals/CAS:...

A bio-immuno assay to determine free tissue-type plasminogen activator (t-PA) in Stabilyte® plasma

This article describes a two-step bio-immuno assay (BIA), which determines active (free) tissue-type plasminogen activator (t-PA) in (acidified) plasma. Plasma samples, diluted in buffer of pH 6.0, are added to the wells of a microtiter plate containing an immobilised monoclonal antibody which binds t-PA without affecting t-PA activity. After an...

New aspects of blood collection and handling procedures for the assessment of t-PA and PAI-1 variables after the introduction of acid blood collection

Blood collection and handling procedures for t-PA activity have thusfar been rather strict and have restrained the use in clinical practice. We evaluated simplifications in the procedures for specifically the use of Stabilyte® vacutainers with respect to time before centrifugation of blood, storage of plasma, times of inversion of the collection...

Constitutive synthesis of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1): Conditions and therapeutic targets

In the population at large and in individual normal volunteers, baseline molar concentratios of t-PA and PAI-1 in plasma show a strong correlation. Evidence is summarized that insulin resistance is a prominent cause of interindividual variation, next to possible contributions of vascular inflammation and steroid hormones. In healthy volunteers,...

Grupo de trabajo de Leiden sobre fibrinolysis: procedimientos de recogida y manipulación de sangre para la evaluación del activador del plasminógeno de tipo tisular (t-PA) y del inhibidor-1 del activador del plasminógeno (PAI-1) [Leiden fibrinolysis working party : blood collection and handling procedures for assessment of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1)]

Procedures of blood collection and handling are different for the various variables in haemostasis and tend to change gradually with progress in knowledge and methods. The Working Party has gathered background information about procedures and discussed minimal requirements specifically for t-PA and PAI-1 assessment. The general procedure from...