bluuebunny/crossref_metadata_2025_split huggingface dataset:
Familial Clustering of Factor VIII and von Willebrand Factor Levels
Authors: Houwing-Duistermaat Jeanine , van Houwelingen Hans , Eikenboom Jeroen , Bertina Rogier , Rosendaal Frits , Kamphuisen Pieter 
Published: March 2018

SummaryRecently, we found that high levels of clotting factor VIII (>150 IU/dl) are common and make an important contribution to thrombotic risk. The determinants of high factor VIII:C are unclear and might be partly genetic. Therefore, we tested the influence of age, blood group and von Willebrand factor (VWF) levels on factor VIII:C levels, and investigated whether factor VIII:C levels are genetically determined. We performed an analysis of 564 female relatives of hemophilia A patients, who had visited our center for genetic counseling. In univariate analysis, AB0 blood group, age and VWF antigen (VWF:Ag) levels all influenced factor VIII:C levels. After adjustment for the effect of VWF:Ag levels, both blood group and age still had an effect on factor VIII:C levels. In sister pairs, the Pearson correlation coefficient between factor VIII:C levels was 0.17 (p = 0.024) and this correlation remained positive (0.15, p = 0.046) after correction for the influence of VWF:Ag. In mother-daughter pairs, no correlation of factor VIII:C levels was found. The correlation of VWF:Ag levels in sisterpairs was 0.41 (p <0.001) and in mother-daughter pairs 0.44 (p <0.001), in line with the assumption that VWF:Ag levels are under control of autosomal genes. Familial influence on plasma factor VIII:C and VWF:Ag levels was investigated with a recently developed familial aggregation test. This test verifies whether familial aggregation of a particular parameter exists in a set of pedigrees. In 435 women from 168 families, factor VIII:C as well as VWF:Ag levels correlated significantly within families, which suggests a familial influence. The familial aggregation was more prominent for VWF:Ag levels than for factor VIII:C levels, possibly because the genetic effect on VWF:Ag levels is larger than on factor VIII:C levels. Our results support the presence of a familial influence on factor VIII:C as well as on VWF:Ag levels.Our results support the presence of a familial influence on factor VIII:C as well as on VWF:Ag levels.
The Histidin-rich Glycoprotein Pro186/Ser Polymorphism Is not Related to Myocardial Infarction in the ECTIM Study
Authors: Poirier Odette , Nicaud Viviane , Ruidavets Jean-Bernard , Evans Alun , Arveiler Dominique , Luc Gerald , Bara Lucienne , Cambien François , Herrmann Stefan-Martin 
Published: March 2018

SummaryThe histidin-rich glycoprotein (HRG) may contribute to coronary heart disease as a consequence of its possible thrombophilic properties. To test this hypothesis we have investigated the Pro186/Ser polymorphism of the HRG gene, which is known to strongly affect plasma HRG levels, in a large multicenter case-control study of myocardial infarction (MI). The results failed to demonstrate any association between the polymorphism and MI or angiographically assessed coronary stenosis.
Nickel Enhances Collagen-induced Platelet Activation Acting by Increasing the Organization of the Cytoskeleton
Authors: Pulcinelli Fabio , Sebastiani Silvia , Pesciotti Marzia , Pignatelli Pasquale , Daniel James , Gazzaniga Pier Paolo 
Published: March 2018

SummaryIn keratinocytes, osteoclasts and enterocytes, Ni2+ acts as an agonist working through selective activation of the polyvalent cation-sensing receptor.We report here that while Ni2+ alone had no direct ability to induce platelet aggregation or secretion, Ni2+ pretreatment produced these responses when platelets were stimulated with subthreshold concentrations of collagen. In addition, pretreatment with Ni2+ significantly enhanced collagen-induced phospholipase C activation and calcium mobilization. Platelet adhesion to collagen was increased and the inhibition of collagen-induced adhesion normally seen after cytochalasin D treatment was significantly diminished.When Ni2+ was added to platelets alone, tyrosine phosphorylation of p60src was increased. Moreover, Ni2+ enhanced the amount of protein, especially actin, found in the low-speed Triton X-100 insoluble cyto-skeleton. Our results indicate that nickel, possibly acting via a platelet cation sensing receptor analogous to that which has been described in other cell types, may cause a rapid tyrosine kinase-dependent cyto-skeleton reorganization leading to enhanced adhesion of platelets to collagen and increasing collagen-dependent responses.
Fibrinogen, Plasminogen Activator Inhibitor-1, and Carotid Intima-Media Wall Thickness in the NHLBI Family Heart Study
Authors: Pankow James , Williams Roger , Evans Gregory , Province Michael , Eckfeldt John , Folsom Aaron 
Published: March 2018

SummarySeveral studies have linked higher plasma fibrinogen and plasminogen activator inhibitor (PAI-1) concentrations with increased risk of cardiovascular disease. We studied whether members of families with increased occurrence of coronary heart disease (CHD) have increased levels of fibrinogen and PAI-1 and whether subclinical carotid atherosclerosis is associated with these two hemostatic factors. Contrary to our hypothesis, fibrinogen and PAI-1 antigen levels were not different between high CHD risk families versus random families. Adjusted for age and family type, fibrinogen and PAI-1 were both associated positively with carotid intima-media thickness assessed by B-mode ultrasound. However, adjustment for lifestyle and medical covariates essentially eliminated these associations. These data suggest 1) elevated fibrinogen and PAI-1 do not explain clustering of CHD in families and 2) fibrinogen and PAI-1 may partly mediate the effects of other risk factors on carotid atherosclerosis, though the data are also consistent with them playing no causal role.
The Diagnostic Value of Thrombopoietin Level Measurements in Thrombocytopenia
Authors: Porcelijn Leendert , Folman Claudia , Bossers Bernadette , Huiskes Elly , Overbeeke Marijke , Schoot C. Ellen , de Haas Masja , Borne Albert E. G. 
Published: March 2018

SummaryIt has been reported that blood trombopoietin (TPO) levels can discriminate between thrombocytopenia due to increased platelet destruction and decreased platelet production. With our TPO ELISA and a glycocalicin ELISA we analysed a large group of patients in detail and could confirm and amplify the above notion in detail.TPO levels were determined in plasma from 178 clinically and serologically well-defined thrombocytopenic patients: 72 patients with idiopathic autoimmune thrombocytopenia (AITP), 29 patients with secondary AITP, 5 patients with amegakaryocytic thrombocytopenia and 72 patients who suffered from various diseases (46 in whom megakaryocyte deficiency was not and 26 in whom it was expected). In addition, we measured the level of glycocalicin as a marker of total body mass of platelets.In all patients with primary AITP and secondary AITP, TPO levels were within the normal range or in some (n = 7) cases only slightly increased. The level of glycocalicin was not significantly different from that of the controls (n = 95). The patients with amegakaryocytic thrombocytopenia had strongly elevated TPO levels and significantly decreased glycocalicin levels. Similarly, among the 72 thrombocytopenic patients with various disorders, elevated TPO levels were only found in patients in whom platelet production was depressed. The mean level of glycocalicin in these patients was decreased compared to that in controls and patients with AITP, but was not as low as in patients with amegakaryocytic thrombocytopenia.In conclusion, all patients with depressed platelet production had elevated levels of circulating TPO, whereas the TPO levels in patients with an immune-mediated thrombocytopenia were mostly within the normal range. Therefore, measurement of plasma TPO levels provides valuable diagnostic information for the analysis of thrombocytopenia in general.Moreover, treatment with TPO may be an option in AITP.
Inhibition of Thrombin-catalyzed Factor V Activation by Bothrojaracin
Authors: Arocas Véronique , Lemaire Charlotte , Bouton Marie-Christine , Bezeaud Annie , Bon Cassian , Guillin Marie-Claude , Jandrot-Perrus Martine 
Published: March 2018

SummaryWe have previously identified and characterized a potent and specific thrombin inhibitor, isolated from Bothrops jararaca, named bothrojaracin. Bothrojaracin interacts with the two positively charged recognition sites of thrombin referred to as exosite 1 and exosite 2, whereas it does not interact with the thrombin active site. Consequently, bothrojaracin inhibits thrombin-induced fibrinogen to fibrin conversion and platelet activation, without inhibition of thrombin-catalyzed cleavage of small synthetic substrates. In the present study, we show that bothrojaracin exerts an anticoagulant effect in plasma, illustrated by the prolongation of the aPTT. Using purified proteins, we observed that the anticoagulant effect of bothrojaracin was not only due to the inhibition of fibrinogen to fibrin conversion, but in addition to the inhibition of factor V activation by thrombin. Bothrojaracin decreased the rate of thrombin-catalyzed proteolysis of factor V and concurrently the generation of factor Va cofactor activity measured in a prothrombinase assay. We compared the effect of bothrojaracin with that of ligands binding specifically exosite 1 (hirudin C-terminal peptide SH54-65) or exosite 2 (heparin, prothrombin fragment 2). SH54-65 delayed thrombin catalyzed factor V activation whereas heparin or prothrombin fragment 2 did not. The thrombin derivatives β- and γ-thrombin, which are defective in their exosite 1, but present with a normally exposed exosite 2, had a reduced capacity to activate factor V, which was not further impaired by the exosite 2 ligands, bothrojaracin, heparin or prothrombin fragment 2. Altogether, our results provide further insight into the anticoagulant effect of bothrojaracin showing that it is a potent inhibitor of the feedback activation of factor V by thrombin, and thus of the up-regulation of its own production by thrombin. Inhibition of thrombin-catalyzed factor V activation by bothrojaracin is mainly mediated through the interaction of the inhibitor with thrombin exosite 1, whereas contribution of the interaction with exosite 2 does not appear to play a direct role in factor V recognition by thrombin.
Warfarin Resistance Is Associated with a Protein Component of the Vitamin K 2,3-Epoxide Reductase Enzyme Complex in Rat Liver
Authors: Cain Dean , Hutson Susan , Wallin Reidar 
Published: March 2018

SummaryWarfarin, the most used drug in the world in long-term anticoagulation prophylaxis, targets the vitamin K 2,3-epoxide reductase (VKOR) of the vitamin K cycle in liver. Recently, the enzyme has been identified as a multicomponent lipid-protein enzyme system in the endoplasmic reticulum (ER) membrane (17). As the first step towards understanding genetic resistance to warfarin, we present in this paper data on VKOR from normal and a strain of warfarin resistant laboratory rats maintained in the United States. Metal induced in vitro assembly of the enzyme complex demonstrates that the glutathione-S-transferase (GST) enzyme component of the complex loses its GST activity upon formation of VKOR. Less VKOR activity is measured upon assembly of the complex from warfarin resistant rats. The GST activity measured in warfarin resistant rats, before assembly of the complex, is 10-fold less sensitive to warfarin inhibition than the GST activity measured in normal rats. Microsomal epoxide hydrolase (mEH) is the second component of VKOR. When incubated with the components of VKOR before assembly of the complex, antibodies raised against mEH prevented formation of the enzyme complex. Sequencing of mEH cDNAs from normal and warfarin resistant rats revealed identical sequences. The data suggest that the mutation responsible for genetic warfarin resistance is associated with the GST component of VKOR.
Contribution of Acute-Phase Proteins and Cardiovascular Risk Factors to Erythrocyte Aggregation in Normolipidemic and Hyperlipidemic Individuals
Authors: Weng Xiaoduan , Roederer Ghislaine , Beaulieu Raymond , Cloutier Guy 
Published: March 2018

SummaryBackground. Numerous studies have demonstrated that elevated concentrations of acute-phase proteins affect red blood cell (RBC) aggregation. Plasma lipids and lipoproteins were also shown to be correlated with RBC aggregation in hypercholesterolemia. However, whether acute-phase proteins promote RBC hyperaggregation in hyper-lipidemic patients is unknown. The main objective of the study was to identify the impact of acute-phase proteins such as fibrinogen (Fib), haptoglobin (Hp), ceruloplasmin (Cp), α1-acid glycoprotein (AGP), α1-antitrypsin (AT), immunoglobulin G (IgG), and albumin (Alb) on RBC aggregation in 35 hyperlipidemic patients. The influence of these proteins in 32 normolipidemic subjects was also determined.Methods and Results. RBC aggregation parameters reflecting the kinetics of rouleau formation and the adhesive strength between RBCs were measured by laser reflectometry. Multivariate forward stepwise linear regression analyses were performed to study the relationship between RBC aggregation and these acute-phase proteins, total cholesterol (TC), triglycerides (TG), high (HDL-C) and low (LDL-C) density lipo-protein cholesterol, age, gender, body mass index (BMI), mean blood pressure (Mpressure), and smoking habit. The kinetics of rouleau formation was positively correlated with the linear combination of IgG and Hp (r = 0.76, p <0.0001) in hyperlipidemic patients, whereas IgG, smoking, AGP and gender were significant independent predictors in healthy subjects (r = 0.79, p <0.0001). The correlations obtained for the models predicting the adhesive strength between RBCs were 0.69 in patients (Alb, HDL-C, IgG, p <0.002) and 0.71 in healthy individuals (AGP, BMI, p <0.0001).Conclusion. This study suggests that acute-phase proteins such as IgG, Hp, AGP and Alb influence significantly and in an independent way the level of RBC aggregation. The close association between RBC aggregation and cardiovascular risk factors further strengthens its clinical importance.
Home Treatment of Mild to Moderate Bleeding Episodes Using Recombinant Factor VIIa (Novoseven) in Haemophiliacs with Inhibitors
Authors: Aledort Louis , Beardsley Diana , Cooper Herbert , Davignon George , Ewenstein Bruce , Gilchrist Gerald , Gill Joan , Glader Bertil , Hoots W. Keith , Kisker C. Thomas , Lusher Jeanne , Rosenfield Cathy , Shapiro Amy , Smith Horace , Taft Edwin , Key Nigel 
Published: March 2018

SummaryObjective. To assess the safety and efficacy of a fixed dose of recombinant activated factor VII (rFVIIa; NovoSeven™) in the home setting for mild to moderately severe joint, muscle, and mucocutaneous bleeding episodes in patients with haemophilia A or B with inhibitors. Design. Multicentre, open-label, single arm, phase III study of one year duration. Methods. Patients or their caregivers administered up to three doses of rFVIIa (90 μg/kg i.v.) at 3 h intervals within 8 h of the onset of a mild to moderate bleeding episode. Once the subject considered that rFVIIa had been “effective” with regard to haemostasis (after 1-3 injections), one further (maintenance) dose of rFVIIa was administered. Results. Of 60 patients enrolled, 56 experienced at least one bleed, and 46 completed the one year study. 614 of 877 bleeds (70%) were evaluable according to protocol definitions. Haemostasis was rated as “effective” in 92% (566/614) of evaluable bleeds after a mean of 2.2 injections. For successfully treated episodes, the time from onset of bleeding until administration of the first injection was 1.1 ± 2.0 h (mean ± SD). Twenty-four hours after initial successful response, haemostasis was reported as having been maintained in 95% of cases. Efficacy was comparable for muscle, joint and target joint, and muco-cutaneous bleeding episodes. In an intent-to-treat analysis of all 877 bleeding events, efficacy outcomes were equivalent to the evaluable bleeds, with an effective response in 88% of treated episodes. Treatment-related adverse events occurred in 32 (3% of all) bleeding episodes and consisted of re-bleeds/new bleeds in more than 50% (18/32) of these events. A single episode of superficial thrombophlebitis was the only thrombotic complication encountered, and there were no patient withdrawals due to adverse events. Development of FVII(a) antibodies could not be detected, and hypersensitivity reactions to rFVIIa were not reported. Conclusion. rFVIIa is effective and well tolerated when used in the home setting to treat mild to moderate bleeding episodes in patients with haemophilia A or B with inhibitors.
Rapid Hemophilia A Molecular Diagnosis by a Simple DNA Sequencing Procedure: Identification of 14 Novel Mutations
Authors: Vidal Francisco , Farssac Elisenda , Altisent Carme , Puig Lluís , Gallardo Dominique 
Published: March 2018

SummaryWe here describe a simple, efficient DNA sequencing procedure for hemophilia A molecular diagnosis. In severe patients we first test for the presence of factor VIII gene intron 22 inversion using a recently described single-tube PCR method. In moderate, mild, or inversion-negative severe patients we systematically sequence the promoter, all exons and splice junctions of factor VIII gene. Specially designed primers allow amplification of 23 PCR products under the same salt conditions and thermocycling parameters. The whole sequencing procedure, from blood extraction to mutation identification, can be readily done within 42 h when using regular instruments or in just 14 h when using a high-throughput sequencer. Thus, this is a versatile and cost-effective strategy with little hands-on time requirements. Since its implementation we have identified mutations in 45/46 hemophilia A patients, 14 of which are novel. Once the genetic defect has been identified, accurate genetic counseling is then easily performed.
Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Does not Inhibit In Vitro Thrombolysis by Pharmacological Concentrations of t-PA
Authors: D’Aprile Anna , Italia Alessandra , Gresele Paolo , Morser John , Semeraro Nicola , Colucci Mario 
Published: March 2018

SummaryTAFI (thrombin activatable fibrinolysis inhibitor) is a plasma procarboxypeptidase that upon activation inhibits the fibrinolytic process by removing the C-terminal lysines from partially degraded fibrin. The generation of activated TAFI (TAFIa) has been suggested to represent a mechanism of thrombus resistance to thrombolytic therapy. However, the ability of TAFI to inhibit fibrinolysis by pharmacological concentrations of t-PA has not been properly investigated. We used an in vitro model consisting of 125I-fibrin blood clots submerged in auto-logous defibrinated plasma. Upon addition of t-PA (125-5000 ng/ml) and CaCl2 (25 mM), samples were incubated at 37° C, and clot lysis was measured at intervals from the radioactivity released into solution. The role of TAFI was assessed either by neutralizing the generated TAFIa with the specific inhibitor PTI (50 g/ml) or by enhancing TAFI activation through the addition of recombinant soluble thrombomodulin (solulin, 1 μg/ml). In our clot lysis model, activation of TAFI amounted to about 20% of inducible carboxypeptidase activity. Addition of PTI, however, produced a significant increase in the extent of lysis only at concentrations of t-PA equal to or lower than 250 ng/ml. When solulin was added to the plasma surrounding the clot, about 70% of TAFI was activated within 15 min. Under these conditions, inhibition of clot lysis was very marked in samples containing 125 or 250 ng/ml of t-PA, but negligible in those containing pharmacological concentrations of the activator (1000 and 5000 ng/ml). Additional experiments suggest that loss of fibrin-dependence by elevated concentrations of t-PA may be one of the mechanisms explaining the lack of effect of TAFIa. Our data indicate that, under our experimental conditions, clot lysis by pharmacological concentrations of t-PA is not influenced by TAFIa even after maximal activation of this procarboxypeptidase.
Vascular Endothelial Growth Factor Enhances the Expression of Urokinase Receptor in Human Endothelial Cells via Protein Kinase C Activation
Authors: Kroon Marielle , Koolwijk Pieter , Vermeer Mario , van der Vecht Bea , van Hinsbergh Victor 
Published: March 2018

SummaryAmong other proteolytic enzymes, the urokinase-type plasminogen activator (u-PA)/plasmin cascade contributes to cell migration and the formation of capillary-like structures in a fibrinous exudate. The u-PA receptor (u-PAR) focuses proteolytical activity on the cell surface of the endothelial cell and hereby accelerates the pericellular matrix degradation. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF)-2 enhance u-PA receptor expression in human endothelial cells. In this paper we show that the protein kinase C (PKC) inhibitors Ro31-8220 and GF109203X inhibit VEGF165-induced u-PAR antigen expression in human endothelial cells, whereas PKC inhibition had no effect on FGF-2-induced u-PAR antigen enhancement. In addition, inhibition of PKC activity had no effect on VEGF165-or FGF-2-induced proliferation in human endothelial cells. We conclude that VEGF165 induces u-PAR via a PKC-dependent pathway, whereas proliferation is induced via a different pathway probably involving tyrosine phosphorylation of proteins downstream of the VEGF receptors.
Platelet Shape Change Evoked by Selective Activation of P2X1 Purinoceptors with α,β-Methylene ATP
Authors: Rolf Michael , Brearley Charles , Mahaut-Smith Martyn 
Published: March 2018

SummarySimultaneous measurements of [Ca2+]i and light transmission were used to examine the relationship between P2X1 receptor activation and functional platelet responses. The P2X1 agonist α,β-MeATP evoked a transient [Ca2+]i increase and a reversible decrease in light transmission; both responses required external Ca2+ and the nucleotidase apyrase. The transmission response was due to shape change only, verified by scanning electron microscopy and insensitivity to Reopro, a GPIIbIIIa antagonist. α,β-MeATP stimulated smaller shape changes than ADP, however P2X1 responses had a lifespan of <2 h following resuspension in saline and may be considerably larger in vivo. A peak [Ca2+]i increase of >50 nM was required for detectable shape change. Overlap of concentration-response relationships for α,β-MeATP-evoked [Ca2+]i and shape change suggests that other second messengers are not involved. Therefore, the physiological P2X1 agonist ATP can contribute to platelet activation, in contrast to its previously described inhibitory action at metabotropic platelet purinoceptors.