bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of recombinant factor VIIa on melagatran-induced inhibition of thrombin generation and platelet activation in healthy volunteers
Authors: Levi Marcel , Sarich Troy , Boström Stig , Eriksson Ulf , Eriksson-Lepkowska Maria , Svensson Mia , Weitz Jeffrey , Elg Margareta , Wåhlander Karin , Wolzt Michael 
Published: April 2004

SummaryThe objectives were to investigate whether activation of the extrinsic coagulation cascade by recombinant factor VIIa (rFVIIa) reverses the inhibition of thrombin generation and platelet activation by melagatran, the active form of the oral direct thrombin inhibitor ximelagatran. In a single-blind, randomized, parallel-group study, volunteers (20 per group) received a 5-hour intravenous (iv) infusion to achieve steadystate melagatran plasma concentrations of approximately 0.5 µmol/L, with a single iv bolus of rFVIIa (90 µg/kg) or placebo at 60 minutes. Prothrombin fragment 1+2, thrombin-antithrombin complex, fibrinopeptide A, β-thromboglobulin, and thrombin-activatable fibrinolysis inhibitor were quantified for venous and shed blood. Activated partial thromboplastin time (APTT), prothrombin time (PT), endogenous thrombin potential, thrombus precursor protein (TpP), and plasmin-α2-antiplasmin complex concentrations were determined in venous blood. Shed blood volume was measured. Melagatran reduced markers of thrombin generation and platelet activation in shed blood and prolonged APTT. rFVIIa increased FVIIa activity, PT, and TpP in venous blood. All other parameters were unaffected. In conclusion, rFVIIa did not reverse the anticoagulant effects of high constant concentrations of melagatran. However, the potential value of higher, continuous or repeated doses of rFVIIa or its use with lower melagatran concentrations has not been excluded.
Strong correlation between the prevalence of cerebral infarction and the presence of anti-cardiolipin/β2-glycoprotein I and anti-phosphatidylserine/prothrombin antibodies
Authors: Kuratsune Hirohiko , Suehisa Etsuji , Kitani Teruo , Iwatani Yoshinori , Kanakura Yuzuru , Nojima Junzo 
Published: April 2004

SummaryCerebral infarction is the most common arterial thromboembolic complication in the anti-phospholipid antibodies (aPL) syndrome. In an effort to clarify the roles of aPL in the pathogenesis of cerebral infarction in patients with SLE, we examined the levels of anti-cardiolipin/β2-glycoprotein I antibodies (antiCL/β2-GPI) and anti-phosphatidylserine/prothrombin antibodies (anti-PS/PT) in addition to lupus anticoagulant (LA) activity in 126 patients with SLE (35 with cerebral infarction and 91 without thrombosis). Both anti-CL/β2-GPI and antiPS/PT strongly correlated with the presence of LA activity. The prevalence of cerebral infarction was obviously higher in the patients who had both anti-CL/β2-GPI and anti-PS/PT (76.5% [26/34 cases], p<0.0001) than in the other patients having antiCL/β2-GPI or anti-PS/PT alone or neither of them (9.8% [9/92 cases]). Furthermore, we studied the in vitro effects of antiCL/β2-GPI and/or anti-PS/PT on the enhancement of platelet activation induced by stimulation with a low concentration of adenosine diphosphate (ADP). The purified IgG containing both anti-CL/β2-GPI and anti-PS/PT caused significant enhancement of platelet activation caused by ADP. However, the purified IgG containing either anti-CL/β2-GPI or anti-PS/PT had no enhancing effects on it. Furthermore, platelet activation was generated by the mixture of anti-CL/β2-GPI-IgG and anti-PS/PT-IgG prepared from individual patients, but not by each fraction alone. These results indicate that anti-CL/β2-GPI and antiPS/PT may cooperate to promote platelet activation, which may contribute to the risk of cerebral infarction in patients with SLE.
Interaction of platelets with liposomes containing dodecapeptide sequence from fibrinogen
Authors: Toma Chikaho , Nishiya Takako 
Published: April 2004

SummaryLiposomes with a covalently bound synthetic peptide containing the dodecapeptide sequence HHLGGAKQAGDV, the putative platelet interaction site at γ400-411 of fibrinogen (dodecapeptide-liposomes), were prepared. These liposomes enhanced platelet aggregation and specifically adhered to platelets activated on the collagen surface. Dodecapeptide-liposomes released encapsulated materials upon interacting with platelets activated on the collagen surface.The rate of content release was dependent on the peptide surface density, indicating that the interaction between the dodecapeptide-liposomes and platelets activated on the collagen surface induces clustering of the surfacecoupled ligands at the binding site on the receptor matrix to facilitate release of the internal contents through the liposome membranes. The level of lipid mixing between the dodecapeptide-liposomes and platelets activated on the collagen surface was relatively low, however it was increased in liposome preparations containing octa-arginine, the (R)8GDV sequence, while content release was maintained at the same level as that of the dodecapeptide-liposomes. The level of content release and lipid mixing for liposome preparations containing the RGD sequence as a ligand (RGD-liposomes) upon interacting with platelets activated on the collagen surface was extremely low. Both the level of the content release and lipid mixing, however, were enhanced in liposome preparations containing octa-arginine, the (R)8RGD sequence. Dodecapeptide-liposomes and RGD-liposomes were not internalized by activated platelets. On the other hand, liposomes containing (R)8PPQ, (R)8RGD, or (R)8GDV were internalized by activated platelets, and the extent of internalization was inversely related to ligand affinity to the target.
Association after linkage analysis indicates that homozygosity for the 46C→T polymorphism in the F12 gene is a genetic risk factor for venous thrombosis
Authors: Tirado Isabel , Mateo José , Oliver Artur , Souto Juan , Santamaria Amparo , Felices Rosa , Borrell Montserrat , Fontcuberta Jordi , Soria José 
Published: April 2004

SummaryIn a family-based study called GAIT (Genetic Analysis of Idiopathic Thrombophilia) that included a genome-wide scan we demonstrated that a polymorphism (46C→T) in the F12 locus jointly influences variability of plasma (Factor XII) FXII levels and susceptibility to thrombotic disease. It then became germane to determine the prevalence of the 46C→T polymorphism and its relative risk of thrombotic disease. We followed up evidence for genetic linkage with a case-control study, including 250 unrelated consecutive Spanish patients suffering from venous thrombotic disease and 250 Spanish subjects matched for sex and age as a controls. We measured FXII levels and genotyped the 46C→T polymorphism, as well as a number of classical risk factors for thrombotic disease. We confirmed that individuals with different genotypes for this polymorphism showed significant differences in their FXII levels. Most importantly, the mutated T allele in the homozygous state (genotype T/T) was associated with an increased risk of thrombosis (adjusted OR of 4.82; 95% CI 1.5-15.6), suggesting that the polymorphism itself is an independent risk factor for venous thromboembolism. This study confirms that the 46C→T polymorphism is a genetic risk factor for venous thrombosis in the Spanish population. In addition, our results confirm that a genome-wide scan coupled with a classical case-control association study is an extremely valuable approach to identify DNA variants that affect complex diseases.
The role of platelets and recombinant factor VIIa on thrombin generation, platelet activation and clot formation
Authors: Chakroun Tahar , Depasse François , Arzoglou Pantelis , Samama Meyer , Elalamy Ismail , Gerotziafas Grigoris 
Published: April 2004

SummaryIn the present study we assessed the effect of platelet counts and rFVIIa on thrombin generation, platelet activation and clot formation after tissue factor pathway activation in human plasma aiming to investigate the mechanism by which rFVIIa induces haemostasis in patients with severe thrombocytopenia. Plasma samples with platelet counts from 5 ×109/l to 150 ×109/l were spiked with rFVIIa (1 µg/ml) or buffer. Clotting was initiated in the presence of diluted thromboplastin. Thrombin generation was assessed using the Thrombogram-Thrombinoscope™ assay. The kinetics of platelet activation was assessed using flow cytometry to measure the expression the Pselectin on platelet membrane of washed platelets suspended in defibrinated homologous PPP. Thromboelastography was used to evaluate the effect of platelets and rFVIIa on the kinetics of clot formation and clot’s firmness. In the presence of low platelet counts the endogenous thrombin potential (ETP) and the maximum concentration of generated thrombin (Cmax) were reduced by 60%-70%.The lag-time of thrombin generation and the time required to reach the Cmax (Tmax) were prolonged, the velocity of platelet activation was decreased and thrombus formation was delayed. Recombinant FVIIa accelerated thrombin generation and platelet activation but it did not significantly modify ETP or Cmax. Recombinant FVIIa enhanced platelet activation in a TF and thrombin dependent manner since its effect on the studied parameters was abolished when TF was omitted or when hirudin was added into the experimental system respectively. Recombinant FVIIa normalized the velocity of clot formation but it did not modify clot firmness, which depended mainly on platelets’ count. In conclusion, in experimental conditions simulating severe thrombocytopenia rFVIIa in the presence of low amounts of TF, accelerates thrombin generation, without increasing the maximum amount of generated thrombin, thus leading in enhanced platelet activation and rapid clot formation.
Erythrocyte sodium/lithium countertransport is associated with thrombotic and fibrinolytic factors in 58-year-old men
Authors: Bokemark Lena , Fagerberg Björn , Herlitz Hans 
Published: April 2004

SummaryThe metabolic syndrome, in which insulin resistance is the core feature, is associated both with dysregulation of thrombosis/ fibrinolysis and erythrocyte sodium/lithium countertransport (SLC).To investigate this further we designed a cross-sectional study to examine whether factors involved in coagulationand fibrinolysis systems were associated with SLC independently of insulin resistance in 93 58-year-old men. SLC was in univariate analysis positively correlated with PAI-1 activity (r = 0.35, p <0.01), tPA antigen (r = 0.38, p <0.01), von Willebrand factor (r = 0.25, p <0.05), protein S (r = 0.26, p <0.05), and C (r = 0.30, p <0.01), and negatively associated with tPA activity(r = −0.28, p <0.01). Since these correlations could be influenced by the components of the metabolic syndrome itself, a separate analysis with adjustment for glucose infusion rate (GIR), plasma insulin, body fat, sagittal diameter of the abdomen (SD) and log serum triglyceride concentration (TG) was conducted. Then SLC was associated with tPA antigen independent of GIR, plasma insulin, body fat, SD and TG. SLC was also associated with protein C independent of GIR, insulin, body fat and SD but not TG. In conclusion, we found a relationship between SLC and the fibrinolytic system that was not related to the metabolic syndrome.
Human α-defensins neutralize fibrinolytic activity exerted by staphylokinase
Authors: Tarkowski Andrej , Bokarewa Maria 
Published: April 2004

SummaryDefensins, cationic peptides with bacteriolytic properties, are abundantly found at inflammation sites and in human coronary vessels. Vascular occlusive diseases, such as myocardial infarction, pulmonary embolism, and peripheral arterial occlusion are presently treated by thrombolytic intervention using staphylokinase, a plasminogen activator of bacterial origin. In this study we assessed a possible interaction between defensins and staphylokinase, both molecules being present in an acutely ill patient. Using an ELISA-based system, we found that staphylokinase and defensins displayed a strong and dose-dependent binding. In contrast, urokinase, another plasminogen activator of endogenous origin, displayed only minimal binding to defensins. Next, we proved that interaction between staphylokinase and defensins led to fuctional consequences resulting in a significant decrease (p<0.002) of plasminogen activation capacity upon complex formation. In contrast, urokinase retained most of its activity even in 10-fold molar excess of defensins. Finally, we found that staphylokinase-triggered lysis of fibrin was efficiently inhibited in the presence of defensins. To assess structural requirements for staphylokinase/defensin interaction, six staphylokinase mutant variants were studied. Inactivation pattern of the tested staphylokinase variants suggested a direct binding of defensins to serine protease-like domain of staphylokinase. In conclusion, we show complex formation between staphylokinase and α-defensins resulting in a significant reduction of fibrinolytic activity. This finding may have clinical implications, since fibrinolytic effects of staphylokinase may be downregulated at the site of vascular occlusion.
In proven deep vein thrombosis, a low positive D-Dimer score is a strong negative predictor for associated malignancy
Authors: Jones Sue , Day Jane , Hoggarth Catherine , Rege Kanchan 
Published: April 2004

SummaryD-Dimer measurements are being increasingly used for negative prediction of deep vein thrombosis (DVT). At our institution, clinical score, D-Dimer assay, plethysmography and, if necessary, Doppler ultrasound are used to secure the diagnosis. We collected the data from 100 consecutive patients proven to have DVT. We examined their medical case notes at diagnosis for concurrent clinical conditions and one year later to look for documented evidence of malignancy. Twenty-two of the 66 patients with D-Dimers greater than 1000 ng/ml were diagnosed with a cancer compared with only 2 of the 34 patients with a presenting D-Dimer score of less than 1000 ng/ml. We propose that a D-Dimer score of less than 1000 ng/ml in proven DVT is a strong negative predictor for malignancy (p = 0.0025).
Prevention of in-stent restenosis via reduction of thrombo-inflammatory reactions with recombinant P-selectin glycoprotein ligand-1
Authors: Tanguay Jean-François , Geoffroy Pascale , Sirois Martin , Libersan Danielle , Kumar Anjali , Schaub Robert , Merhi Yahye 
Published: April 2004

SummaryThe binding of leukocyte P-selectin glycoprotein ligand-1 (PSGL-1) to platelet P-selectin is central to post-angioplasty restenosis. Although intracoronary stents limit the mechanical component of restenosis, they cause marked thrombo-inflammation and neointimal proliferation leading to greater late luminal loss. We sought to demonstrate that P-selectin antagonism, using recombinant PSGL-1 (rPSGL-Ig), is effective in reducing platelet-leukocyte reactions and in-stent restenosis in doubleinjured porcine coronary arteries. Two weeks after initial injury by angioplasty to the coronary arteries, stents were implanted at the injury-induced lesion site, 15 min after an IV bolus administration of a vehicle or rPSGL-Ig (1 mg/kg). Four weeks later, adhesion of 51Cr-platelets and 111In-neutrophils and histomorphometric analyses were performed. In-stent residual lumen was almost 3 fold larger in rPSGL-Ig-treated arteries (3.1 ± 0.4 mm2) as compared to control (1.1 ± 0.2 mm2), which correspond to 64% vascular stenosis in control with no change in rPSGL-Ig animals. For a similar injury score, in-stent neointima was significantly reduced by 30 to 40% in the rPSGL-Ig group and quantitative coronary angiography showed a significant 35% reduction in late lumen loss. These effects of rPSGL-Ig were associated with a respective 70% and 53% reduction in platelet and neutrophil adhesion. In conclusion, pretreatment with rPSGL-Ig reduces thrombo-inflammatory responses, neointimal proliferation, and in-stent restenosis. P-selectin antagonism offers a promising therapy to improve clinical outcomes of coronary stenting.
Encapsulation of a plasminogen activator speeds reperfusion, lessens infarct and reduces blood loss in a canine model of coronary artery thrombosis
Authors: Leach J. , Patterson Eugene , O’Rear Edgar 
Published: April 2004

SummaryIn the present study, a polymer-encapsulated plasminogen activator was investigated as an alternative to restore blood flow more effectively than free plasminogen activator. While current fibrinolytic agents have limited efficacy, attributable to delayed onset of sustained reperfusion and bleeding complications, encapsulated plasminogen activators have shown promise in addressing these shortcomings. A polymer-encapsulated plasminogen activator could offer an effective formulation with a prolonged shelf-life. In this study, coronary artery thrombosis was produced in the anesthetized dog by the injection of thrombin + whole blood, and then one of five randomly selected formulations was administered intravenously: saline, blank microcapsules, free streptokinase (FREE SK), streptokinase and blank microcapsules (FREE SK + BLANK), or streptokinase entrapped in polymer microcapsules (MESK). MESK significantly accelerated the time to reperfusion compared to FREE SK or FREE SK + BLANK. Additionally, substantial reductions were observed in residual clot mass, infarct mass, reocclusion episodes, fibrinogen depletion and blood loss with MESK compared to FREE SK. The results of this study demonstrate that MESK accelerates thrombolysis and the restoration of blood flow compared to identical dosages of FREE SK while also reducing systemic fibrinogenolysis and blood loss. Microencapsulation may produce an improved dosage form for restoring arterial blood flow and reducing bleeding complications with thrombolytic therapy.
Penthalaris, a novel recombinant five-Kunitz tissue factor pathway inhibitor (TFPI) from the salivary gland of the tick vector of Lyme disease, Ixodes scapularis
Authors: Mather Thomas , Ribeiro José , Francischetti Ivo 
Published: April 2004

SummaryTick saliva is a rich source of molecules with antiinflammatory, antihemostatic and immunosupressive properties. In this paper, a novel tick salivary gland cDNA with sequence homology to tissue factor pathway inhibitor (TFPI) and coding for a protein called Penthalaris has been characterized from the Lyme disease vector, Ixodes scapularis. Penthalaris is structurally unique and distinct from TFPI or TFPI-like molecules described so far, including Ixolaris, NAPc2, TFPI-1 and TFPI-2. Penthalaris is a 308-amino-acid protein (35 kDa, pI 8.58) with 12 cysteine bridges and 5 tandem Kunitz domains. Recombinant Penthalaris was expressed in insect cells and shown to inhibit factor VIIa (FVIIa)/tissue factor(TF)-induced factor X (FX) activation with an IC50 of ∼ 100 pM. Penthalaris tightly binds both zymogen FX and enzyme FXa (exosite), but not FVIIa, as demonstrated by column gel-filtration chromatography. At high concentrations, Penthalaris attenuates FVIIa/TF-induced chromogenic substrate (S2288) hydrolysis and FIX activation. In the presence of DEGR-FX or DEGR-FXa, but not des-Gla-DEGR-FXa as scaffolds, tight and stoichiometric inhibition of FVIIa/TF was achieved. In addition, Penthalaris blocks cell surface-mediated FXa generation by monomer (de-encrypted), but not dimer (encrypted) TF in HL-60 cells. Penthalaris may act in concert with Ixolaris and other salivary anti-hemostatics in order to help ticks to successfully feed on blood. Penthalaris is a novel anticoagulant and a tool to study FVIIa/TF-initiated biologic processes.
The anticoagulant action of recombinant human activated protein C (rhAPC, Drotrecogin α activated): comparison between cord and adult plasma
Authors: Gallistl Siegfried , Koestenberger Martin , Baier Katrin , Fritsch Peter , Greilberger Joachim , Jürgens Günther , Muntean Wolfgang , Cvirn Gerhard 
Published: April 2004

SummaryThe present study was performed to compare the anticoagulant efficiency of recombinant human activated protein C (rhAPC) in cord with that in adult plasma. RhAPC is a promising candidate to improve the outcome of severe sepsis. However, different anticoagulant efficiency of rhAPC in cord compared with adult plasma has to be expected due to physiological low plasma levels of tissue factor pathway inhibitor (TFPI) and antithrombin (AT) present in neonates, two inhibitors known to markedly influence the anticoagulant action of APC. Clot formation was induced in our experiments by addition of high (30 µM) or low (20 pM) amounts of lipidated tissue factor (TF). High amounts of TF are conventionally applied in standard clotting assays, whereas plasma activation with low amounts of TF probably better matches the conditions in vivo. We demonstrate that under low coagulant challenge increasing amounts of rhAPC (0.1 – 0.5 µg/ml final plasma concentration) dose-dependently prolonged clotting time and suppressed thrombin potential and prothrombin fragment 1 + 2 generation in both cord and adult plasma. The same was true for experiments performed under high coagulant challenge when 4 – 16 µg/ml of rhAPC were added. Whereby, cord plasma was significantly more susceptible to addition of rhAPC in the presence of high amounts of TF and adult plasma was significantly more susceptible to addition of rhAPC in the presence of low amounts of TF. We demonstrate that increased anticoagulant efficiency of rhAPC in adult plasma under low coagulant challenge is attributable to the physiological high levels of TFPI and AT present in adults.
Levels of annexin IV and V in the plasma of pregnant and postpartum women
Authors: Masuda Junko , Takayama Eiji , Satoh Ayano , Ida Michiru , Shinohara Tadashi , Kojima-Aikawa Kyoko , Ohsuzu Fumitaka , Nakanishi Kuniaki , Kuroda Koichi , Murakami Mitsutaka , Matsumoto Isamu , Suzuki Kimihiro 
Published: April 2004

SummaryAnnexin (Anx) V is pivotal in the maintenance of pregnancy by preventing the activation of blood coagulation. The homology of the amino acid sequence between Anx IV and Anx V is highest in Anx family proteins. However, little is known about the roles of Anx IV in pregnancy.The aim of this study is to clarify the roles of circulating Anx IV and Anx V in normal pregnancy. Subjects were non-pregnant women (n = 50), 120 pregnant women, and maternal subjects just after delivery (n = 53) or postpartum (n = 67). Anx IV in the plasma of non-pregnant women was at a concentration 20 times that of Anx V. The plasma levels of Anx IV suddenly increase after delivery, but Anx V levels remain low during this period. Anx IV and Anx V exert similar levels of anticoagulant activity. Anx IV protein was expressed on the basal surface of syncytiotrophoblasts; Anx V protein, on the apical surface of syncytiotrophoblasts. These results suggest that Anx IV enters the maternal bloodstream just after delivery and might play a role in preventing disseminated intravascular coagulopathy, and that Anx V helps to prevent clotting in the placenta during pregnancy.