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BACKGROUND AND OBJECTIVE: Vascular fibrinolysis, a major natural defense mechanism against thrombosis, is a highly regulated process. The aim of this study was to evaluate the effect of endotoxin, tumor necrosis factor-alpha (TNFalpha) and interleukin-1alpha (IL-1alpha), on the fibrinolytic potential of cultured human umbilical vein endothelial cells (HUVEC). DESIGN AND METHODS: Samples of stimulated conditioned media were collected over a period of 24 hours to determine: plasminogen activator (PA) and plasminogen activator inhibitor (PAI) activity, PAI-1 mRNA, tissue-type plasminogen activator (t-PA) antigen and urokinase-type plasminogen activator (u-PA) antigen. RESULTS: Similar changes were observed after endotoxin and cytokine stimulation: there was a significant increase of PAI activity (p

BACKGROUND AND OBJECTIVE: Acute generalized, widespread bleeding is often related to disseminated intravascular coagulation (DIC), a pathologic process which complicates the clinical course of many diseases and is characterized by huge amounts of thrombin and plasmin within the circulation. The final result is the consumption of platelets, coagulation factors and inhibitors, as well as secondary hyperfibrinolysis, all leading to diffuse hemorrhage and microthromboses. This review article examines the present attitudes to the diagnosis and treatment of overt DIC in clinical practice, emphasizing the importance of an accurate differential diagnosis from some other processes characterized by acute generalized, widespread bleeding. INFORMATION SOURCES: The authors have been working in this field, both at experimental and clinical levels, contributing original papers for many years. In addition, material examined in this review includes articles published in journals covered by MedLine, recent reviews in journals with high impact factor and in relevant books on hemostasis and thrombosis. STATE OF ART AND PERSPECTIVES: DIC is an intermediary mechanism of disease which complicates the clinical course of many well-known disorders. Although the systemic hemorrhagic syndrome is the predominant clinical manifestation, massive intravascular thrombosis frequently occurs contributing to ischemia and associated organ damage, making the mortality rate of this condition high. Current concepts on the pathophysiology, laboratory diagnosis and management of DIC are presented. Complex pathophysiological interrelations make the diagnosis of the etiology of the DIC difficult in clinical practice, although simple tests are useful for identification of patients with the process. Laboratory diagnosis of DIC is mainly based on screening assays, which allow a rapid diagnosis, whereas some other highly sensitive but more complex assays are not always available to routine clinical laboratories. The management of DIC is based on the treatment of the underlying disease, supportive and replacement therapies and the control of the coagulation mechanisms. Although some advances have been achieved, management decisions are still controversial, so that therapy should be highly individualized depending on the nature of the DIC and severity of clinical symptoms. Many syndromes sharing common findings with DIC, such as primary hyperfibrinolysis or thrombotic thrombocytopenic purpura, should be excluded. Finally, new therapeutic approaches to the management of this potentially catastrophic syndrome are required

Plasmin-alpha2-antiplasmin complexes (PAP) are considered good markers of fibrinolytic activation in vivo. The presence of neoantigens in these complexes offers the possibility to develop specific immunoassays to determine PAP levels. We have developed a sensitive PAP purification method in vitro by adding urokinase to fresh plasma followed by affinity chromatography to lysine-sepharose and elution with epsilon-aminocaproic acid. This material, characterized by SDS-PAGE and Western blotting, was used to raise monoclonal antibodies (MoAbs). We describe a new enzyme linked immunosorbent assay (ELISA) to quantify PAP complexes in plasma. The assay follows the sandwich principle and is based on two MoAbs, CPL12 and CPL15, that bind to the modified alpha2-antiplasmin moiety and the plasmin moiety of the complex respectively. The calibration curve was constructed with definite concentrations of purified PAP. The lower limit of the assay is 75 ng/ml and the variation coefficients are 3.5% (intra-assay) and 10-6% (interassay). A mean value of 573.5+/-131.4 ng/ml was obtained from PAP concentration in a healthy population (n = 30). Significantly higher PAP levels were observed under diverse clinical conditions in which fibrinolysis is activated: clinical sepsis, acute myocardial infarction (AMI), malignancy, diabetes, pregnancy, elderly people and thrombolytic therapy. From our results we conclude that this ELISA is suitable to measure in vivo plasma PAP levels.

Development of monoclonal antibodies capable of inhibiting the specific binding of t-PA to fibrin.After immunization of Balb/c mice with recombinant t-PA (rt-PA) we selected the monoclonal antibody MA3B5 by its ability to inhibit the binding of t-PA to fibrin, and the MA2C1 devoid of this property. The influence of such antibodies was evaluated on fibrin plates, amidolytic assays and clot lysis assays. Furthermore, their interference with the activator bound to fibrin was assayed with a spectrophotometric solid phase assay (SOFIA).The results showed that MA3B5 totally inhibited the t-PA induced fibrinolytic activity on fibrin plates, reduced amidolytic activity by 86.5% and inhibited the clot lysis induced by t-PA in a dynamic system. In contrast, the MA2C1 showed no inhibition. By assessing the binding of t-PA to fibrin with the SOFIA assay we could demonstrate that only the MA3B5 reduced significantly (up to 90% with 100 micrograms/mL of antibody) the amount of t-PA bound to fibrin surface.We have purified and characterized a monoclonal antibody which specifically blocks the fibrin binding site of t-PA.

BACKGROUND AND OBJECTIVE: The control of well-known atherosclerotic risk factors represents the optimal strategy in the prevention of acute coronary syndromes. It was the aim of this work to analyze the effects of a long-term cardiac rehabilitation program on the changes of fibrinolysis parameters and plasma lipid profile in coronary patients. DESIGN AND METHODS: The study was carried out in 30 (M/F:22/8, mean age 47 years) survivors of a first acute myocardial infarction (AMI) and in 30 healthy controls who underwent a cardiac rehabilitation program (9 months duration). Samples were taken before, at 3 and 9 months after the beginning of the program to measure: tissue-type plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI-1) activity and antigen. A lipid profile including cholesterol (both HDL and LDL) and lipoprotein(a) was also assessed. The Wilcoxon and Mann-Whitney tests were used for statistical comparisons. RESULTS: There was a marked decrease of functional PAI-1 after 3 and 9 months as compared with baseline in AMI patients (p < 0.01). Results showed a significant increase of HDL-cholesterol (p < 0.01) and decrease of lipoprotein(a) levels after the exercise program (p < 0.01). INTERPRETATION AND CONCLUSIONS: The cardiac rehabilitation program improved fibrinolysis, by reducing the functional levels of PAI-1, and ameliorated the lipid profile by decreasing lipoprotein(a) and increasing HDL-cholesterol in patients with AMI. A long-term cardiac rehabilitation has positive effects on some risk factors for coronary disease.