Changes In Fibrinolytic Activity Research Articles

Plasma from patients with vaccine-induced immune thrombotic thrombocytopenia displays increased fibrinolytic potential and enhances tissue-type plasminogen activator but not urokinase-mediated plasminogen activation

BackgroundVaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare complication of adenovirus vector-based COVID-19 vaccines. VITT is associated with markedly raised levels of D-dimer; yet, how VITT modulates the fibrinolytic system is unknown. ObjectivesWe aimed to compare changes in fibrinolytic activity in plasma from patients with VITT, patients diagnosed with venous thromboembolism (VTE) after vaccination but without VITT (VTE–no VITT), and healthy vaccinated controls. MethodsPlasma levels of plasmin-antiplasmin (PAP) complexes, plasminogen, and alpha-2-antiplasmin (α2AP) from 10 patients with VITT, 10 patients with VTE–no VITT, and 14 healthy vaccinated controls were evaluated by enzyme-linked immunosorbent assay and/or Western blotting. Fibrinolytic capacity was evaluated by quantitating PAP levels at baseline and after ex vivo plasma stimulation with 50-nM tissue-type plasminogen activator (tPA) or urokinase for 5 minutes. ResultsBaseline PAP complex levels in control and VTE–no VITT individuals were similar but were ∼7-fold higher in plasma from patients with VITT (P < .0001). VITT samples also revealed consumption of α2AP and fibrinogenolysis consistent with a hyperfibrinolytic state. Of interest, VITT plasma produced significantly higher PAP levels after ex vivo treatment with tPA, but not urokinase, compared to the other groups, indicative of increased fibrinolytic potential. This was not due to D-dimer as addition of D-dimer to VTE–no VITT plasma failed to potentiate tPA-induced PAP levels. ConclusionA marked hyperfibrinolytic state occurs in patients with VITT, evidenced by marked elevations in PAP, α2AP consumption, and fibrinogenolysis. An unidentified plasma cofactor that selectively potentiates tPA-mediated plasminogen activation also appears to exist in the plasma of patients with VITT.

Tranexamic acid in a mouse model of cerebral amyloid angiopathy: setting the stage for a novel stroke treatment approach

BackgroundSymptomatic intracerebral hemorrhage (sICH) commonly occurs in patients with cerebral amyloid angiopathy (CAA). Amyloid also initiates plasminogen activation and might promote sICH. ObjectivesAs amyloid-driven plasmin formation can be blocked by tranexamic acid (TXA), we aimed to evaluate the biodistribution and long-term consequences of TXA on brain amyloid-beta (Aβ) levels, inflammation, and neurologic function in APP/PS1 mice. MethodsAPP/PS1 mice overexpressing the mutant human amyloid precursor protein and wild-type littermates were randomized to TXA (20 mg/mL) or placebo in the drinking water for 6 months. TXA in plasma and various organs was determined by liquid chromatography-mass spectrometry. Plasmin activity assays were performed to evaluate changes in fibrinolytic activity. Neurologic function was evaluated by Y-maze and parallel rod floor testing. Proximity ligation–based immunoassays were used to quantitate changes of 92 biomarkers of inflammation. Brain Aβ levels were assessed by immunohistochemistry. ResultsLong-term oral TXA administration inhibited fibrinolysis. TXA accumulated in the kidney (19.4 ± 11.2 μg/g) with 2- to 5-fold lower levels seen in the lung, spleen, and liver. TXA levels were lowest in the brain (0.28 ± 0.01 μg/g). Over 6 months, TXA had no discernible effect on motor coordination, novelty preference, or brain Aβ levels. TXA reduced plasma levels of epithelial cell adhesion molecule and increased CCL20. ConclusionLong-term TXA treatment does not alter brain Aβ levels or impact neurologic behavior in mice predisposed to amyloid deposition and had minor effects on the levels of inflammatory mediators. This finding supports the safety of TXA and lays the foundation for TXA as a novel treatment to reduce sICH in patients with CAA.

Changes in fibrinolytic activity and coagulation factors after epicardial left atrial appendage closure in patients with atrial fibrillation.

The left atrial appendage (LAA) is known to be the primary source of thrombus formation in atrial fibrillation (AF). We investigate whether epicardial LAA occlusion (LAAO) from the cardiovascular system has an effect on coagulation and prothrombotic status in AF. Twenty-two patients with nonvalvular AF, who were not currently receiving oral anticoagulation (OAC) therapy, participated in a single-center prospective study. We measured fibrinogen and plasminogen levels along with plasma fibrin clot permeability, clot lysis time (CLT) and endogenous thrombin potential (ETP) before the LAAO procedure, at discharge and 1 month afterward. One month after the LAAO procedure, plasma fibrin clot permeability improved by 39.3% as measured by clots prepared from peripheral blood (P=0.019) and also after adjustment for fibrinogen (P=0.027). Higher plasma fibrin clot permeability was associated with improved clot susceptibility to lysis (r=-0.67, P=0.013). CLT was reduced by 10.3% (P=0.0020), plasminogen activator inhibitor-1 antigen levels were reduced by 52% (P=0.023) and plasminogen activity was increased by 8.9% (P=0.0077). A trend toward decreased thrombin generation, reflected by a decreased ETP and peak thrombin generated was also observed 1 month after LAAO procedure (P=0.072 and P=0.087, respectively). No differences were observed in tissue-type plasminogen activator and thrombin-activatable fibrinolysis inhibitor plasma levels (both P>0.05). Obtained results seem to confirm that LAA plays a key role in thrombogenesis. Elimination of LAA from the circulatory system may improve fibrin clot permeability and susceptibility to fibrinolysis in peripheral blood.

ANALYSIS OF THE CONDITION OF NEWBORNS BORN TO MOTHERS INFECTED WITH CORONAVIRUS

One of the current problems of modern obstetrics is the diagnosis, treatment and prevention of intrauterine growth retardation. This pathology ranks second after prematurity among the causes of low-birth-weight babies. The prevalence of fetal retardation varies worldwide from 6.5 to 30.0% of all births, of which about 23% are very low birthweight and about 38% extremely low birthweight babies. A new coronavirus infection, caused by the viral pathogen SARS-CoV-2, which contributes to thrombotic microangiopathy in combination with hypercoagulation syndrome, is currently ongoing. During physiological pregnancy, there is known to be an increased risk of complications associated with both bleeding and thrombosis, which are affected by changes in fibrinolytic activity and hypercoagulable state, endothelial dysfunction, and changes in blood rheological properties. It significantly increases the risk of pregnancy complications such as pre-eclampsia, placental insufficiency, fetal hypoxia, and therefore leads to intrauterine growth retardation of the fetus. This study analyzed the status of newborn babies and the incidence of intrauterine growth retardation in women who had contracted coronavirus infection. Two groups of women were included in study: the first included those who became pregnant 3 to 6 months after a new coronavirus infection, and the second was a control group. The study found that women in the first group were more likely to have pre-eclampsia and their babies were more likely to be diagnosed with intrauterine growth retardation.

АНАЛИЗ СОСТОЯНИЯ НОВОРОЖДЕННЫХ ДЕТЕЙ ПАЦИЕНТОК, ПЕРЕНЕСШИХ КОРОНОВИРУСНУЮ ИНФЕКЦИЮ

Abstract. One of the urgent problems of modern obstetrics is the diagnosis, treatment and prevention of intrauterine growth retardation. This pathology ranks second after prematurity among the causes of the birth of children with low body weight. The frequency of intrauterine growth retardation varies in different countries of the world from 6.5-30.0% of all newborns, of which about 23% are found among children with very low body weight and about 38% with extremely low body weight. Currently, an outbreak of a new coronavirus infection continues, caused by the viral pathogen SARS-CoV-2, which contributes to the formation of thrombotic microangiopathy in combination with hypercoagulability syndrome. It is known that during physiological pregnancy, the risk of complications associated with both bleeding and thrombus formation increases, which is affected by changes in fibrinolytic activity and the state of hypercoagulability, endothelial dysfunction, and changes in the rheological properties of blood. This virus can significantly increase the risk of developing pregnancy complications such as preeclampsia, placental insufficiency, fetal hypoxia and, as a result, leads to intrauterine growth retardation. The study analyzes the condition of newborns and the incidence of intrauterine growth retardation in women who have recovered from coronovirus infection. The study included two groups of women: the first group consisted of patients whose pregnancy occurred 3-6 months after a new coronavirus infection, and the second group was a control group. As a result of the study, it was found that women of the first group more often suffered from preeclampsia, and their children were more often diagnosed with intrauterine growth retardation.

FIBRINOLYTIC ACTIVITY IN HEART TISSUE IN HYPOTHYROID AND HYPERTHYROID RATS UNDER THE INFLUENCE OF EXOGENOUS MELATONIN AND BLINDING CONDITIONS (ENUCLEATION)

The aim of our scientific work was to study the effect of exogenous melatonin on the indicators of fibrinolytic processes in the heart tissues and to analyze the changes in fibrinolytic activity occurring in the heart tissues of enucleated hyper- and hypothyroid white rats. The experiments were carried out on white nonlinear male rats weighing 0.12-0.14 kg. 4 experimental groups of animals were formed. The control group consisted of 11 normothyroid rats, which were injected with a melatonin solution in appropriate volumes. The animals were euthanized under light ether anesthesia. Samples of the examined heart tissue were ground in a glass homogenizer with borate buffer (pH 9.0). The homogenate was used in biochemical analysis. Determination of the total, enzymatic and non-enzymatic fibrinolytic activity (TFA, EFA, NFA, respectively) in the heart tissues was carried out by the method of azofibrin lysis (LLC "Simko", Ukraine). Statistical processing of the results was carried out by the method of variation statistics using the Student's test. Experimental studies on nonlinear male white rats have shown that the introduction of exogenous melatonin, as well as modeling the conditions of endogenous melatonin overproduction by blinding (enucleation) cause an increase in the intensity of enzymatic and non-enzymatic fibrinolysis in heart tissue in normotyroid animals. At other hand, enucleation causes an increase in the intensity of fibrinolysis in the tissues of the heart in hypothyroid rats, but not in hyperthyroid.

Time course and outcomes associated with transient versus persistent fibrinolytic phenotypes after injury: A nested, prospective, multicenter cohort study.

Temporal changes in fibrinolytic activity after injury and their impact on outcomes remain poorly defined. We conducted a prospective, multicenter cohort study to determine the incidence of fibrinolytic phenotypes after injury and the trajectories and associated outcomes of these phenotypes over time. We included adults that arrived within 6 hours of injury to three American Level I trauma centers. Clot lysis at 30 minutes (LY-30) was measured at presentation and at 3 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, and 120 hours. LY-30 was used to categorize patients into the following fibrinolytic phenotypes: fibrinolysis shutdown (SD, LY-30 ≤0.8%), physiologic fibrinolysis (PHYS, LY-30 >0.8% to <3%), or hyperfibrinolysis (HF, LY-30 ≥3%). We used multivariable logistic regression to estimate adjusted odds ratios for mortality. We included 795 adults (median age, 38 years; median Injury Severity Scale score, 21). In total, 44% presented with SD, 36% with PHYS, and 21% with HF. Mortality was highest among those who presented with HF (20%) followed by SD (10%) and PHYS (7%) (p = 0.001). While mortality within the first 24 hours was highest with admission HF (14% vs. 5% SD vs. 4% PHYS; p = 0.001), both admission HF (7%) and SD (6%) had higher mortality after 24 hours compared with PHYS (3%) (p = 0.04). All patients who presented with HF switched into another phenotype or died within 24 hours. The majority of patients that presented in SD remained in that phenotype, including 71% at 24 hours and 72% at 120 hours. Persistent SD at 24 hours was independently associated with increased mortality after 24 hours (odds ratio, 3.20; 95% confidence interval, 1.51-6.67). Approximately 70% of major trauma patients who present with SD remain in this phenotype up to 120 hours postinjury. In contrast, patients presenting with HF transition into another phenotype or die within 24 hours. While early mortality is highest with the HF phenotype, persistent SD at 24 hours is associated with elevated late mortality. Prognostic and epidemiological study, level II.

Fibrinolytic activity of the blood plasma in gastroduodenopathies induced by non-steroi¬dal anti-inflammatory drugs in patients with osteoarthrosis, regarding pathogenic Helicobacter pylori strains

Objective. This research aims at estimating the changes of fibrinolytic activity of the blood plasma in gastroduodenopathies induced by non-steroidal anti-inflammatory drugs in patients with osteoarthrosis regarding the pathogenic Helicobacter pylori strains presence.Material and methods. The study involved 68 patients suffering from osteoarthrosis with concomitant Helicobacter pylori-associated gastro-duodenopathies induced by non-steroidal anti-inflammatory drugs. The patients were divided into groups depending on the presence of vacA and cagA Helicobacter pylori strains. Helicobacter pylori strains were detected in the stool, blood and biopsy samples using the technique of polymerase chain reaction. All the patients were investigated by means of general, clinical, laboratory and instrumental methods of examination. The computations were done using «Biostatistics» and «Statistica® 6.0» (StatSoftІnc., USA) programs. Results. The increase in the intensity of the fibrinolytic activity of the blood plasma was observed in all investigated patients. However, the patients with concomitant Helicobacter pylori pathogenic and ulcerogenic strain cagA+/vacA+ experienced an increase in total fibrinolytic activity by 13,14% and 36,4% respectively compared to the patients with cagA+/vacA- Helicobacter pylori strains and by 26,92% and 60,0% compared to the patients with cagA-/vacA+ Helicobacter pylori strains. Nonenzymatic fibrinolytic activity in patients with cagA+/vacA+ Helicobacter pylori strains tended to increase in comparison with cagA+/vacA- strains and cagA-/vacA+ Helicobacter pylori strains. Conclusion. A substantial increase in the fibrinolytic activity of the blood plasma in the examined patients with Helicobacter pylori vacA+/cagA+ compared to the patients with Helicobacter pylori vacA+/cagAand Helicobacter pylori vacA-/cagA+ has been reliably established.

Validation of a modified thromboelastometry approach to detect changes in fibrinolytic activity.

BackgroundThus far, validated whole blood assays used in in vitro fibrinolysis experiments using thromboelastometry (ROTEM) are lacking or have yet to be tested in humans.The objective was first, to establish a standardized modified ROTEM approach to detect both hypo- and hyperfibrinolysis. And second, to perform a technical and clinical validation of the assay.MethodsBlood was used of healthy volunteers, patients with sepsis, patients after cardiothoracic surgery, pregnant women, and cirrhotic liver disease patients. A whole blood tissue factor (TF) activated ROTEM assay with and without the addition of recombinant tissue plasminogen activator (rTPA) was developed. Plasma fibrinolysis determinants were measured in all volunteers and patients.ResultsThirty five pM TF and additions of 125 and 175 ng/ml rTPA resulted in full lysis within 60 min in healthy volunteers. Coefficients of variation were below 10 % without and below 20 % with rTPA addition. In sepsis the hypofibrinolytic ROTEM profiles with 175 ng/ml rTPA were in line with the plasma determinants (high PAI-1, high fibrinogen, low tPA activity, and high d-dimers). After cardiothoracic surgery, reduced fibrinogen and platelet levels accounted for the reduced maximum clot firmness. The hypofibrinolytic profile is attributed to tranexamic acid use and elevated PAI-1 levels. The lowest rTPA concentration in cirrhosis resulted in hyperfibrinolysis in only few of the patients. In pregnancy normal profiles were found.DiscussionOur high rTPA concentration demonstrates hypofibrinolytic profiles adequately in sepsis and after cardiothoracic surgery. Our low rTPA concentration of 125 ng/ml seems too high for demonstrating hyperfibrinolysis in cirrhotic liver disease.ConclusionsWe were able to present a validated whole blood ROTEM approach to fibrinolysis testing using added rTPA, which can be of added value next to classical plasma based fibrinolysis assays.

Coagulation factor XIIIa is inactivated by plasmin

AbstractCoagulation factor XIIIa (FXIIIa) is a transglutaminase that covalently cross-links fibrin and other proteins to fibrin to stabilize blood clots and reduce blood loss. A clear mechanism to describe the physiological inactivation of FXIIIa has been elusive. Here, we show that plasmin can cleave FXIIIa in purified systems and in blood. Whereas zymogen FXIII was not readily cleaved by plasmin, FXIIIa was rapidly cleaved and inactivated by plasmin in solution (catalytic efficiency = 8.3 × 103 M−1s−1). The primary cleavage site identified by mass spectrometry was between K468 and Q469. Both plasma- and platelet-derived FXIIIa were susceptible to plasmin-mediated degradation. Inactivation of FXIIIa occurred during clot lysis and was enhanced both in plasma deficient in fibrinogen and in plasma treated with therapeutic levels of tissue plasminogen activator. These results indicate that FXIIIa activity can be modulated by fibrinolytic enzymes, and suggest that changes in fibrinolytic activity may influence cross-linking of blood proteins.

Fibrinolytic changes in pregnant women on highly active antiretroviral therapy.

Objectives:To report on the changes in fibrinolytic activity in human immunodeficiency virus (HIV) infected pregnant women who are undergoing highly active antiretroviral therapy (HAART).Methods:Blood was collected from 50 HIV positive women on HAART (test subjects), and 50 HIV positive women not on HAART (controls). These women were attending the prevention of mother to child clinic (PMTCT) of the University of Benin Teaching Hospital, Benin City, Nigeria from January to June 2014. Standard manual techniques were used to estimate plasma fibrinogen concentration (PFC), euglobulin lysis time (ELT), packed cell volume (PCV), and plasma viscosity (PV).Results:The mean ± standard error of mean (SEM) of PFC was 4.02±0.13g/l and ELT from the test subjects was 378±15 mins was significantly higher (p<0.05) compared with the control subjects (PFC 3.46±0.12g/l and ELT 267±9.0mins). The PCV or hematocrit values in the test subject was 29.1±0.38%, which was significantly lower (p<0.05) compared with the control subject (31.3±0.43%). The PV in the test subject was 1.76±0.02 mPa/s, while the control subjects was higher (1.73±0.02 mPa/s). This increase was not statistically significant (p>0.05). There were differences in the various parameters investigated when the various trimesters were compared. These differences did not, however, follow a particular pattern.Conclusion:Highly active antiretroviral therapy can cause changes in fibrinolytic activity that may predispose pregnant women to hyperfibrinogenemia and anemia.

The Changes of Fibrinolytic Activity of Nattokinase in Artificial Gastrointestinal Environment and Human Digestive Juice

Purpose: To search for the change of fibrinolytic activity of different forms of nattokinase when they were treated in human digestive juice, artifical gastric and intestinal juice differently, and to lay the foundation of a proper pharmaceutical dosage form of nattokinase. To provide direct evidences that Nattokinase products can be administered orally and to screen a suitable dosage form for oral administration of nattokinase.Methods: The non-crushed sample was prepared through the solid fermentation of soybean meal at 37°C for 36 h, and evaporation at 70°C for 8 h, The fine and ultra-fine powder were gotten from the non-crushed sample by the micronizer and ultra micronizer. Nattokinase extract was the supernatant liquid of 0.9% saline of non-crush samples. The nattokinase’s fibrinolytic activity of non-crushed sample, fine powder, ultra-fine powder and extract treated in artifical and human digestive were measured by the Fibrin plate method. Results: Three kind of solid form samples still remain about 80% fibrinolytic activity in artificial gastric juice for 4 h, and the fibrinolytic activity of nattokinase extract is 48.7% at the end of treatment. Treated in artificial gastric juice for 4 hours, then handled in artificial intestinal fluid for 4 h, the final fibrinolytic activity of fine and ultra fine powder is 47.0% and 51.0%. The fibrinolytic activity of extract is 79.8% at the end of treatment in human digestive juice for 4 h. At the beginning of treatment in human digestive juice the enzyme activity of fine and ultra fine powder is 130.8U/mL and 132.1U/mL, however, after treatment for 4 h the enzyme activity is 158.7U/mL and159.6U/mL, which is near to the total enzyme activity of sample. Conclusion: Nattokinase products can be administered orally, and solid preparations of nattokinase are more suitable for oral route. The optimum dosage form for oral administration of nattokinase is enteric-coated capsules containing ultra fine powder.

Fibrinolytic Activity and Platelet Function in Subjects with Obstructive Sleep Apnoea and a Patent Foramen Ovale: Is There an Option for Prevention of Ischaemic Stroke?

Obstructive sleep apnoea (OSA) carries an increased risk of ischaemic stroke, but the underlying mechanism is not clear. As right-to-left shunting can occur through a patent foramen ovale (PFO) during periods of apnoea, we investigated nocturnal changes in fibrinolytic activity and platelet function in subjects who had OSA with or without PFO and in controls. We determined plasminogen activator inhibitor 1 (PAI-1) activity and antigen and platelet activation parameters. The severity of OSA was verified by polygraphy and PFO was detected by ear oximetry. We found a higher PAI-1 activity and antigen and a lower ratio of 2,3-dinor-PGF1α to 2,3-dinor-TXB2 in the subjects with OSA than in the controls. Linear regression analysis showed the apnoea-hypopnoea index (β-coefficient, 0.499; P = 0.032) and PFO (β-coefficient, 0.594; P = 0.015) to be associated independently with PAI-1 activity in the morning, while the increment in PAI-1:Ag from evening to morning was significantly associated with the presence of PFO (rs = 0.563, P = 0.002). Both OSA and PFO reduce fibrinolytic activity during nocturnal sleep. We hypothesize that subjects having both OSA and PFO may develop a more severe prothrombotic state during sleep than those having either OSA or PFO alone.

The plasminogen activator inhibitor system in colon cancer cell lines is influenced by the CO2 pneumoperitoneum

PurposeLaparoscopic surgery in the treatment of colon carcinoma causes pH value alterations as well as changes in fibrinolytic activity. This results in enhanced proliferation of colon carcinoma cells in vitro and also in enhanced growth of liver metastasis when compared to isobaric (gasless) laparoscopy in vivo. So far, the direct influence of CO2 pneumoperitoneum on the invasiveness and metastatic capabilities of colon cancer cells remains unclear. We therefore evaluated transcripts of the uPA system.MethodsThe influence of CO2 pneumoperitoneum on the gene expression of plasminogen activator inhibitor-1 (PAI-1), urokinase-type plasminogen activator (uPA), and tissue-type plasminogen activator (tPA) was investigated in colon carcinoma cell lines (HT116, SW48, and WiDr) and mesothelial cells employing a pneumoperitoneum chamber in vitro. Quantitative gene expression data were collected using real-time RT-PCR and statistical analysis was performed by means of analysis of variance and Bonferroni correction.ResultsThe expression of uPA and PAI-1 was increased in colon carcinoma cell lines when cultivated at pH 6.1, a value corresponding to intraabdominal pH values during CO2 insufflation. Elevated PAI-1 mRNA levels were also observed when CO2 was simultaneously applied with a pressure of 10 mmHg. In contrast, there were no significant changes in mesothelial cells in the investigated parameter.ConclusionThe conditions of CO2 pneumoperitoneum cause changes in the expression of genes controlling the fibrinolytic activity. The increase of PAI-1 and uPA can contribute to the enhancement of metastasis and invasive potential of tumour cells. Therefore, changes in the conditions of laparoscopy may well optimise laparoscopic therapy in colon cancer.

P2 Tissue factor pathway inhibitor (TFPI) in normal and complicated pregnancy

s selected for Poster Presentation P1 Reduced fibrinolytic activity in women after delivery in Benin City, Nigeria J.O. Osakue, O.I. Ajayi, A. Ande. Department of Physiology and Obstetrics/Gynecology, University of Benin and University of Benin Teaching Hospital, Nigeria Abstract: Fibrinolytic activity (using ELT) and plasma fibrinogen concentration in 50 mothers just after delivery were assessed (giving 50 mothers and 50 cord samples). Also 50 healthy women without delivery were used as controls. All these were to ascertain if there is any change in fibrinolytic activity in women after delivery. Methodology: Fifty women (22 35 years) with normal delivery were used for this study (150 samples). Blood samples were collected and investigations were performed before noon. ELT (fibrinolytic activity) was carried out using the method of Cecil Hougie (1986) and plasma fibrinogen concentration (PFC) was estimated using Ingram clot weight method (1961). The t-distribution test was used to test for level of significance between mean of both test and controls, P< 0.05 was significant. Results: The results show significantly lower fibrinolytic activity in mothers and significantly higher fibrinogen concentration than controls (P< 0.05). Maternal PFC and ELT values were also significantly higher than cord samples. Conclusion: There is reduced fibrinolytic activity and increased fibrinogen concentration in mothers immediately after delivery. This may be a proctective coagulative mechanism against excessive post partum haemorhage. Fibrinolytic activity (using ELT) and plasma fibrinogen concentration in 50 mothers just after delivery were assessed (giving 50 mothers and 50 cord samples). Also 50 healthy women without delivery were used as controls. All these were to ascertain if there is any change in fibrinolytic activity in women after delivery. Methodology: Fifty women (22 35 years) with normal delivery were used for this study (150 samples). Blood samples were collected and investigations were performed before noon. ELT (fibrinolytic activity) was carried out using the method of Cecil Hougie (1986) and plasma fibrinogen concentration (PFC) was estimated using Ingram clot weight method (1961). The t-distribution test was used to test for level of significance between mean of both test and controls, P< 0.05 was significant. Results: The results show significantly lower fibrinolytic activity in mothers and significantly higher fibrinogen concentration than controls (P< 0.05). Maternal PFC and ELT values were also significantly higher than cord samples. Conclusion: There is reduced fibrinolytic activity and increased fibrinogen concentration in mothers immediately after delivery. This may be a proctective coagulative mechanism against excessive post partum haemorhage. P2 Tissue factor pathway inhibitor (TFPI) in normal and complicated pregnancy A. Ittel1, F. Bretelle2, M.A. Coulomb2, L. Boubli2, G. Sebahoun1, D. Arnoux1. Departments of 1Hematology and 2Obstetrics, CHU Nord, Marseille, France TFPI plays a crucial role in haemostatic balance by regulating the initial step of blood coagulation. Since it is expressed by both endothelial and trophoblastic cells; TFPI could be of particular importance at the placental level. In this study, we measured free TFPI antigen (elisa method; Diagnostica Stago) in 4 groups of women: (1) 35 healthy nonpregnant women with no oral contraception and no history of pregnancy complications; (2) 47 women at the beginning (<12 weeks) and (3) 103 women at the end of a normal pregnancy; (4) women with late pregnancy complications (IUFD, IUFGR, PE) at the time of obstetrical event (n = 75) and/or at distance of pregnancy (n = 66). In normal pregnancy, mean TFPI level at delivery was significantly higher than in the first trimester (7.5 vs 5.2 ng /ml; p < 0.001) but lower than in non-pregnant controls (9.1 ng /ml; p = 0.002). In patients, TFPI levels varied widely at the time of the adverse event but were found significantly lower than in non-pregnant controls when measured at distance of pregnancy. (mean 6.6 vs 9.1 ng/ml, p < 0.001), TFPI level being below the lowest value of controls in 23% of patients. Among other pro-thrombotic abnormalities, low TFPI levels could play a role in the occurrence of placental vascular complications. P3 A score based prevention strategy of venous thromboembolism in pregnant women Y. Dargaud1, L. Rugeri1, M.C. Vergnes2, B. Arnutti3, P. Amaranto4, C. Negrier1, J. Ninet5, P. Gaucherand6, M.C. Trzeciak1. 1Unite d’Hemostase Clinique, CHU de Lyon, France, 2Laboratoire d’Hemostase, CHU de Bordeaux, France, 3Service d’Hemostase et d’Hemovigilance, CH de Valence, France, 4Service de Medecine Interne, CH de Roanne, France, 5Service de Medecine Interne, CHU de Lyon, France, 6Service de Gynecologie Obstetrique, CHU de Lyon, France Objective: To evaluate the usefulness of score based management of pregnancies with high risk of venous thromboembolism (VTE). Table 1. VTE risk prediction score

Impact of cilazapril on fibrinolytic system in hypertensive patients

Impaired fibrinolysis is associated with thromboembolic complications in hypertensive patients. Cardiovascular morbidity/mortality rates have been reported high even after lowering the elevated blood pressure with antihypertensive drugs. We investigated the effects of clinically used dosages of cilazapril on the fibrinolytic system in hypertensive patients. The present study was performed among 30 hypertensive patients (22 women, eight men), who received 2.5-5.0 mg cilazapril daily for 1 month. Before and after the cilazapril treatment, patients' venous blood was drawn for fibrinolytic tests. The fibrinolytic activity was examined utilizing the euglobulin clot lysis time and fibrin plate methods. Using the fibrin plate method, as compared with the pretreatment group, we observed a 57% increased activity in the hypertensive patients receiving cilazapril (P < 0.001). When assessed by the euglobulin clot lysis time method, the activity due to cilazapril treatment was found to be relatively low, although highly significant (approximately 20%, P < 0.001). Changes in fibrinolytic activity were observed in 23 (77%) hypertensive patients after cilazapril treatment; however, their blood pressure remained normal. The remaining seven patients' (23%) blood pressures and fibrinolytic activity did not change significantly after cilazapril treatment. In conclusion, we suggest that the observed differential fibrinolytic activity between the pre and post cilazapril treatment values is due to the plasminogen activators released from the vascular endothelium, which may have been stimulated by cilazapril. It appears that cilazapril is not only an angiotensin-converting enzyme inhibitor but also a stimulator for fibrinolytic activity, which may be an added component in reducing thromboembolic complications in hypertensive patients.

Defibrotide Counteracts the Modifications of Anti-Thrombotic Phenotype of Endothelial Cells Induced by Thalidomide.

Introduction: Patients with Multiple myeloma are at relatively high risk of developing thromboembolic events, usually deep vein thromboses (DVT). There are numerous contributing factors, including therapy, such as thalidomide, where DVT has been identified as a major toxicity, especially when thalidomide is used in combination with other treatments such as dexamethasone. The mechanisms by which thalidomide predisposes to thrombosis are not well understood. Defibrotide (DF) is an orally biovailable polydisperse oligonucleotide with anti-thrombotic, pro-fibrinolytic and anti-adhesive properties. Previously, DF has been shown to dose-dependently counteracted the increase in Plasminogen Activator Inhibitor-1 (PAI-1) expression and decrease on tissue plasminogen activator (t-PA) activity after lipopolysaccharide (LPS) stimulation of endothelial cells in vitro.Methods and Results: We have conducted in vitro studies using human microvascular endothelial cells (HMEC) in order to investigate the effect of different doses of thalidomide on various fibrinolytic factors. In addition, we evaluated whether DF modulates changes of fibrinolysis induced by thalidomide. HMEC were treated with 50 and 100μg/ml of thalidomide for 24 hours in presence and absence of DF (at a dose of 150μg/ml). t-PA and PAI-1 gene expression were evaluated through real time polymerase chain reaction (RT-PCR) of cDNA prepared from HMEC. Release of t-PA and PAI-1 were evaluated by imunoenzymatic assay (ELISA). Furthermore, we evaluated the fibrinolytic activity of cell surpernatant using a fibrin clot plate assay. In this method the fibrin clot was formed by mixing fibrinogen, plasminogen and thrombin. The plasmin generated by the cell surpernatant was able to digest fibrin and also hydrolyzed the chromogenic substrate S-2251. The RT-PCR results showed that thalidomide reduces t-PA (2.2 fold) and increases PAI-1 gene expression (4.0 fold) in HMEC cells, whereas DF was able to counteract this effect by up-regulating the t-PA and down-regulating PAI-1 gene expression induced by thalidomide (8.8 and 2.0 fold, respectivielly). Similar results was observed analyzing t-PA release by HMEC cells treated with different concentrations of thalidomide with and without DF. Thalidomide significantly reduces the t-PA released in both concentrations (p<0.001) and DF significantly increase the release of t-PA reduced by thalidomide (p<0.01). The changes of fibrinolytic activity in HMEC by thalidomide and the capacity of DF to restore the fibrinolysis was confirmed by analyzing the lyses of fibrin clots with endothelial cell surpernatant (p<0.01).Conclusions: These results show that DF is able to counteract the alterations of fibrinolytic factors in HMEC treated with thalidomide. Whilst further studies in preclinical MM models are underway, these data suggest a potential role for DF in the prevention of DVT induced by thalidomide and support ongoing clinical trials of DF in combination with thalidomide-based treatment.

Alterations in the Fibrinolytic Cascade Post-transplant: Evidence of a Bimodal Expression Pattern

Changes in the fibrinolytic system that occur after cardiac transplantation (CTx) and the factors that influence such changes have been poorly described, yet may be important in determining the varying morphologic features of transplant-related coronary artery disease (TxCAD). Baseline demographic as well as serial clinical information and plasma fibrinolytic levels were prospectively recorded pre-CTx and at multiple time-points post-CTx in 110 de novo cardiac transplant recipients. We noted a biphasic change in fibrinolytic activity over the first year of CTx with an early immediate decline in plasminogen activator inhibitor-1 (PAI-1) activity (p > 0.001) matched with stable PAP (plasmin) activity corresponding to an "enhanced" fibrinolytic state early post-CTx. This was followed by a significant increase at 6 months (p = 0.004) and 1 year (p < 0.001) in PAI-1 activity concomitant with a significant decline in PAP after 3 months (p = 0.005 at 3 months, p < 0.001 at 6 months, p < 0.001 at 1 year) corresponding to an "impaired" fibrinolytic state late post-CTx. The biphasic nature of the fibrinolytic system observed herein may account for the varying morphologic features of TxCAD.

Changes in fibrinolytic activity after angiotensin II receptor blockade in therapy-resistant hypertensive patients.

In hypertensive patients, the activated renin-angiotensin system induces a prothrombotic state resulting from imbalance between coagulation and fibrinolysis. Although blood pressure cannot be regulated in therapy-resistant hypertensive patients, they may still be responsive to medication that attenuates the renin-angiotensin system. our objective was to study possible attenuating properties of angiotensin II type 1 receptor blockers (AT1RBs) on the prothrombotic state in therapy-resistant hypertensive patients, focusing on parameters of fibrinolysis and coagulation. Fourteen therapy-resistant hypertensive patients received AT1RB eprosartan infusion (45 and 150 microg kg(-1)) (study group), and 33 therapy-resistant hypertensive patients received saline (0.9%) infusion (control group) prior to renal angiography. Baseline values of parameters of coagulation and fibrinolysis were set at 1.00, and relative changes were calculated. Plasminogen activator inhibitor type 1 (PAI-1) antigen showed non-significant decreases in both the study group (arterial 1.00-0.45, venous 1.00-0.42) and control group (arterial 1.00-0.84, venous 1.00-0.88). PAI-1 activity significantly decreased in the study group (arterial 1.00-0.72, venous 1.00-0.71) and control group (arterial 1.00-0.83, venous 1.00-0.94). In the study group, tissue-type plasminogen activator (t-PA) antigen decreased significantly (arterial 1.00-0.62, venous 1.00-0.67), whereas t-PA activity significantly increased (arterial 1.00-6.15, venous 1.00-2.66). In the control group, t-PA antigen remained unchanged. No changes were observed in blood pressure during and after infusion of eprosartan. Therapy-resistant hypertensive patients show beneficial changes in fibrinolytic activity after infusion of a non-pressor dose of AT1RB.

Plasma fibrinolysis and postoperative deep vein thrombosis.

In 23 high risk patients the change in plasminogen activator activity in response to surgical operation was studied by euglobulin lysis time (ELT) and fibrin plate lysis before, during and for up to 6 days following a major surgical procedure. Fibrin degradation products (FDP) were also measured. The aim was to relate any changes to postoperative deep vein thrombosis (DVT) as diagnosed by the 125I fibrinogen test. Peroperative increase and postoperative inhibition of fibrinolytic activity were seen in all the patients. Changes in fibrinolytic activity as measured by the ELT and during the first 24 hours by the fibrin plate technique were similar. This suggests that during this period the response was independent of plasma fibrinogen changes. There was no significant difference in these parameters between patients who developed DVT and those who did not. The relationship between venous thrombo-embolism and elevation of serum FDP was confirmed.