bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inter-laboratory Variability of Anti-β2-glycoprotein I Measurement
Authors: Schousboe Inger , Tincani Angela , Sanmarco Marielle , Kveder Tanja , de Moerloose Philippe , Boffa Marie-Claire , Arvieux Josiane , Reber Guido 
Published: March 2018

SummaryInter-laboratory variability of anti-β2-glycoprotein I antibody measurements (IgG and IgM) was investigated in the frame of the European Forum on Antiphospholipid Antibodies and its Standardization Group. Twenty-eight samples from patients with autoimmune diseases, two samples from blood donors and a set of six calibrators obtained by dilution with normal plasma of a pool of patient samples were sent to 21 European centers. Six of them used commercial kits and the others home-made assays. Marked differences in the steepness of the calibration curves obtained with the calibrator provided were observed. The standard deviations of sample measurement were high. Cut-off of positivity varied from 7 to 90 Forum Units (FU) for IgG and from 10 to 138 FU for IgM, whereas the rate of positivity varied from 50 to 93% for IgG and from 13 to 70% for IgM. No clear relationship between cut-off values and positivity rate could be established for either isotype. Adopting a common cut-off did not markedly improve the overall agreement between centers in positive/negative sample classification. Because of the majority of low positive samples, excellent concordance between centers (as defined by kappa values from 0.8 and 1) occurred only in 13% of cases for IgG and in 6% of cases for IgM, because many selected samples were low-positive. Despite the large variability of anti-β2-glycoprotein I measurements between centers, the agreement on results with highand medium-positive samples was good.
Von Willebrand Factor Modulates Factor VIII Immunogenicity: Comparative Study of Different Factor VIII Concentrates in a Haemophilia A Mouse Model
Authors: Behrmann Mathias , Pasi John , Saint-Remy Jean-Marie , Kotitschke Ronald , Kloft Michael 
Published: March 2018

SummaryThe development of an immune response towards factor VIII (FVIII) remains the major complication of haemophilia A replacement therapy. Product-related risk factors have recently been identified on the basis of epidemiological studies, but the mechanism is not understood. To this end, various commercially available FVIII concentrates were administered by the IV route to FVIII-knockout mice and the resulting immune response was characterised. Significantly higher inhibitor titres (Bethesda assay) were observed for one recombinant FVIII and one plasma-derived FVIII product depleted in von Willebrand factor (VWF). Inhibitor titres were reduced upon pre-incubation of FVIII with purified VWF. Epitope specificity of anti-FVIII IgG was characterised using FVIII-fragments produced in E. coli. Concentrates with no or reduced VWF-level elicited antibodies recognising predominantly the acidic a1 and a3 regions. Addition of VWF prior to injection also modified the epitope specificity. FVIII concentrates, therefore, show qualitative and quantitative variations in immunogenicity, which are at least partly modulated by VWF.
Distribution of Endothelial Cell Protein C/Activated Protein C Receptor (EPCR) During Mouse Embryo Development
Authors: Crawley James , Gu Jian-Ming , Ferrell Gary , Esmon Charles 
Published: March 2018

SummaryThe endothelial cell protein C receptor (EPCR) augments protein C activation by the thrombomodulin•thrombin complex. Deletion of the EPCR gene in mice has been reported to lead to embryonic lethality before embryonic day 10 (E10.0). To identify potential mechanisms responsible for this lethality, we performed an immunohistological analysis of EPCR distribution during mouse embryogenesis. EPCR was detected in the trophoblast giant cells at the feto-maternal boundary from E7.5 and at later time points in the trophoblasts of the placenta, suggesting a role in the haemostatic regulation of the maternal blood that irrigates these surfaces. In the embryo, EPCR was weakly detected in aortic endothelial cells from E13.5. Thereafter, EPCR levels increased in certain large blood vessel endothelial cells suggesting that the specificity of EPCR to large vessels is conferred in utero. However, not until postnatal day 7 did the intensity and distribution of EPCR staining mimic that observed in adult mice.Abbreviations: APC – activated protein C, AP – alkaline phosphatase, EC – endothelial cell, EPCR – endothelial cell protein C/activated protein C receptor, FITC – fluorescein isothiocyanate, HRP – horseradish peroxidase, PBS – phosphate-buffered saline, TM – thrombomodulin, WT – wild–type
The Diagnostic Value of Compression Ultrasonography in Patients with Suspected Recurrent Deep Vein Thrombosis
Authors: Lensing Anthonie , Bernardi Enrico , Villalta Sabina , Bagatella Paola , Girolami Antonio , Prandoni Paolo ,   for the DERECUS Investigators Group
Published: March 2018

SummaryDiagnosis of recurrent deep-vein thrombosis (DVT) is difficult because of limitations in distinguishing acute from old thrombi. In the past, an ultrasound method for diagnosis of recurrent ipsilateral DVT was developed, which relies on repeated measurements of the diameters of the common femoral and popliteal veins. To assess the safety of withholding anticoagulation from patients with improved or stable compression vein diameters, 205 consecutive patients presenting with suspected recurrent ipsilateral DVT were evaluated. The vein diameter was measured under compression with the transducer and compared with earlier ultrasound results. Patients with stable or improved ultrasound findings had repeat ultrasound assessments after 2 (± 1) and 7 (± 1) days. Patients with repeatedly normal ultrasound results were followed-up for six months to determine the incidence of symptomatic recurrent venous thromboembolism.Of the 205 patients, 153 had stable or improved ultrasound findings. Repeat ultrasound assessment became abnormal in 3, and recurrence was confirmed by venography in all. A six months follow-up was done in the remaining 150 patients with repeatedly normal ultrasound tests and showed 2 (1.3%; 95% CI, 0.02 to 4.7%) confirmed non-fatal venous thromboembolic complications. The positive predictive value of a stable or improved ultrasound was 90% (95% CI, 77 to 97%).In conclusion, it is safe to withhold anticoagulant treatment from patients with suspected recurrent ipsilateral DVT in whom compression ultrasonography showed improved or stable vein diameters.
The Structure of Synthetic Oligosaccharides in Relation to Factor IXa Inhibition
Authors: Hérault J. P. , Gaich C. , Bono F. , Driguez P. A. , Duchaussoy P. , Petitou M. , Herbert J. M. 
Published: March 2018

SummaryWe investigated the effect of various oligosaccharides (OS) on the inhibition of factor IXa by antithrombin (AT) in a purified system. The OS comprised the AT-binding pentasaccharide sequence prolonged by saccharide chains with various lengths and charges. We show that factor IXa inhibition depended on the molecular weight of the OS. Factor IXa was not inhibited by the AT-binding pentasaccharide alone, but was inhibited if it was prolonged by a sulphated dodecasaccharide at the non-reducing end. The overall charge was also important since factor IXa inhibition was negligible if the pentasaccharide was prolonged by a non-sulphated dodecasaccharide. Using compounds containing a non-sulphated spacer, we showed that the central part of the OS was not critical. This study therefore demonstrates that the minimal OS structure necessary for catalysing factor IXa inhibition by AT is close to that required for catalysing thrombin inhibition.
Reduced Factor V Concentration and Altered FV1/FV2 Ratio do not fully Explain R2-associated APC-resistance
Authors: Castoldi Elisabetta , Nicolaes Gerry , Tans Guido , Rosing Jan , Govers-Riemslag José 
Published: March 2018

SummaryCarriership of the factor V (FV) R2 haplotype is associated with mild APC-resistance, moderately reduced FV levels and a relative increase of the more thrombogenic FV isoform, FV1. Since low FV levels and increased FV1 can theoretically cause APC-resistance, we investigated whether these alterations can quantitatively account for R2-associated APC-resistance. In order to determine the effect of FV concentration and FV isoform composition on the APC-response, we reconstituted FV-deficient plasma with purified FV1 and FV2 in different molar ratios and to varying FV concentrations. APC sensitivity ratios (APCsr) were determined with the Coatest® APCTM Resistance V, which probes the effect of APC on both FV-a and FVIIIa-inactivation, and with the Immunochrom® APC response test, which only quantifies the effect of APC on FVIII(a)-inactivation. In both assays, low FV concentrations and/or high relative amounts of FV1 rendered plasma samples more resistant to APC. APCsr were also determined in FVdeficient plasma reconstituted with purified FV at levels and isoform ratios observed in R2-homozygotes (98% FV, 42% FV1) and agematched controls (119% FV, 26% FV1). In both tests the APCsr of reconstituted control plasma was the same as that of plasma from controls, whereas reconstituted R2-plasma was less APC-resistant than plasma from homozygous carriers of the R2 haplotype. We conclude that the low FV levels and altered FV isoform ratio cannot fully explain R2-associated APC-resistance.
15-Deoxy-Δ12,14-Prostaglandin J2 Inhibits Tissue Factor Expression in Human Macrophages and Endothelial Cells: Evidence for ERK1/2 Signaling Pathway Blockade
Authors: Eligini S. , Banfi C. , Brambilla M. , Camera M. , Barbieri S. S. , Poma F. , Tremoli E. , Colli S. 
Published: March 2018

SummaryBasic and clinical evidence has provided insight into the molecular events that link inflammation and coagulation. Increased expression of tissue factor (TF) by circulating and vascular cells has been indicated as responsible for the thrombotic complications associated with acute and chronic inflammation. TF is indeed inducible in circulating and vascular cells by cytokines and bacterial lipopolysaccharide (LPS) and its expression triggers the coagulation. The cyclopentenone prostaglandins are naturally occurring prostaglandin D2 (PGD2) derivatives that comprises prostaglandin J2 (PGJ2) and its metabolites Δ12-PGJ2 and 15-deoxyΔ12, 14-prostaglandin J2 (15d-PGJ2). These compounds, detected in vivo in a later phase of the inflammatory response, are characterized by anti-inflammatory activity and participate to the resolution of inflammation. We have here investigated the effect of 15d-PGJ2 on TF expression in human macrophages and endothelial cells (HUVEC). Our results indicate that 15d-PGJ2 down-regulates LPSand TNFα-induced TF activity, protein and mRNA through inhibition of TF gene transcription. The effect of 15d-PGJ2 is targeted to the NF-κB/I-κB pathway and to the mitogen activated protein kinase ERK1/2. A role of PPARγ activation in TF inhibition by 15d-PGJ2 was excluded. We conclude that 15d-PGJ2 negatively affects TF expression in macrophages and endothelial cells through a PPARγ-independent mechanism. This down-regulation may be crucial to limit excessive blood clotting activation in immuno-inflammatory diseases.
DX-9065a inhibition of factor Xa and the prothrombinase complex: mechanism of inhibition and comparison with therapeutic heparins
Authors: Rezaie Alireza 
Published: March 2018

SummaryFactor Xa (fXa) is the key enzyme of the prothrombinase complex that generates thrombin hence it is a good target for antithrombotic therapy. Here, the anti-fXa and anti-prothrombinase activities of DX-9065a which is an active-site directed inhibitor of fXa, and therapeutic heparins which are dependent on antithrombin (AT) for their anticoagulant function, were studied in amidolytic and proteolytic activity assays. It was found that DX-9065a is a competitive inhibitor of the Spectrozyme FXa (SpFXa) cleavage by both fXa and prothrom-binase with similar Ki values of ~10-20 nM. However, DX-9065a acted as a non-competitive inhibitor of prothrombin activation by prothrombinase with a Ki of ~26 nM. On the other hand, therapeutic heparins were effective catalysts of both fXa and prothrombinase inhibition by AT in the presence of SpFXa, but were ineffective in the presence of prothrombin. Further studies revealed that Tyr99, a residue in the extended S2-S4 binding pocket of fXa, plays a key role in determination of specificity of the DX-9065a interaction.
Plasma membrane Ca2+-ATPase isoform 4b is phosphorylated on tyrosine 1176 in activated human platelets
Authors: Wan Tina , Zabe Martin , Dean William 
Published: March 2018

SummaryPlasma membrane Ca2+-ATPase isoform 4b (PMCA4b) is phosphorylated on a tyrosine residue during platelet activation resulting in inhibition of its ATPase activity. We now report that tyrosine 1176 (Y1176) in the carboxyl (C-) terminal domain of PMCA4b is the phosphorylated residue. Two tyrosine residues located in the C-terminus of PMCA4b, Y1122 and Y1176 can be removed by calpain-dependent cleavage. This truncation removes all of the tyrosine phosphates added to PMCA during platelet activation. Sequence analysis indicates that Y1176 is a likely substrate for focal adhesion kinase (FAK), while Y1122 is not located in a tyrosine phosphorylation motif. This is the same residue we reported earlier to be phosphorylated by Src kinase in vitro. Thus we conclude that Y1176 is the only tyrosine phosphorylated during platelet activation. Results of co-immunoprecipitation, treatment with tyrosine kinase inhibitors and integrin inhibition experiments suggest that FAK is responsible for PMCA4b tyrosine phosphorylation during platelet activation.
Correlates of thrombin generation in patients with advanced prostate cancer
Authors: Caprini Joseph , Goldshteyn Sofia , Dohnal James , Vesely Sara , Shevrin Daniel , Lind Stuart 
Published: March 2018

SummaryThrombin generation is increased in men with advanced prostate cancer. Thrombin has the ability to interact with, and affect the biology of, a variety of cell types including prostate cancer cell lines. We therefore looked for correlations between thrombin generation and other markers of disease activity in spot urine samples obtained from men with advanced prostate cancer. Excretion of part of the prothrombin activation peptide F1+2 (called here iF2), interleukin-6 (IL-6), the bone turnover marker deoxypyridinoline (DpD), and vascular endothelial growth factor (VEGF) were quantitated in spot urine samples collected from 37 men with hormone-refractory prostate cancer. Following log transformation of the data, significant correlations were found by univariate analysis between the excretion of a marker of thrombin generation (iF2) and IL-6, DpD and VEGF, as well as between IL-6 and DpD or VEGF excretion. No correlation was found between any marker and serum PSA level. After multivariate analysis, a significant correlation remained between thrombin generation and IL-6 excretion. Analysis of a second urine specimen obtained from 19 of the subjects 1 to 7 months after the first also revealed a significant correlation between thrombin generation and IL-6, DpD, and VEGF excretion. These data provide evidence of a correlation between thrombin generation/coagulation system activation and IL-6 generation in patients with cancer. They provide a rationale for studying the effects of inhibitors of thrombin generation upon the biology of prostate cancer.
High Plasma Concentration of Factor VIIIc Is a Major Risk Factor for Venous Thromboembolism
Authors: in 't Anker Pieternella , Koopman Marianne , Reitsma Pieter , Prins Martin , van den Ende Abraham , Büller Harry , Kraaijenhagen Roderik 
Published: March 2018

SummaryEstablished risk factors, including deficiencies of protein C, protein S or antithrombin and the factor V Leiden and prothrombin mutation, are present in about one third of unselected patients with venous thromboembolism. In addition to these inherited thrombophilic defects, elevated plasma levels of factor VIIIc have been suggested to be important in the pathogenesis of (recurrent) venous thromboembolism. The objective of this study was to assess the relevance of factor VIIIc plasma concentration in consecutive patients with venous thromboembolism.We studied the prevalence of elevated plasma levels of factor VIIIc in 65 patients with a proven single episode and in 60 matched patients with documented recurrent venous thromboembolism. The reference group consisted of 60 ageand sex-matched patients who were referred for suspected venous thromboembolism, which was refuted by objective testing and longterm clinical follow-up. To minimalize the influence of the acute phase, blood was obtained at least 6 months after the thromboembolic event and results were adjusted for fibrinogen and C-reactive protein. Factor VIIIc was re-determined several years after the first measurement in a subset of patients to evaluate the variability over time. To study a possible genetic cause, a family study was done.In the control, single and recurrent episode group, the prevalences of plasma levels of factor VIIIc above 175 IU/dl (90th percentile of controls) were 10% (95% CI: 4 to 21%), 19% (95% CI: 10 to 30%) and 33% (95% CI: 22 to 47%), respectively. For each 10 IU/dl increment of factor VIIIc, the risk for a single and recurrent episode of venous thrombosis increased by 10% (95% CI: 0.9 to 21%) and 24% (95% CI: 11 to 38%), respectively. Both low and high plasma levels of factor VIIIc were consistent over time (R = 0.80, p = 0.01). A family study indicated a high concordance for elevated factor VIIIc plasma concentrations among first degree family members. Adjustment for fibrinogen, C-reactive protein and known thrombophilic risk factors did not change the observed association of elevated factor VIIIc with thrombosis.Elevated plasma levels of factor VIIIc are a significant, prevalent, independent and dose-dependent risk factor for venous thromboembolism. It also predisposes to recurrent venous thromboembolism.
Hemostatic Parameters and Platelet Activation Marker Expression in Cyanotic and Acyanotic Pediatric Patients Undergoing Cardiac Surgery in the Presence of Tranexamic Acid
Authors: Levin Elena , Wu John , Alexander John , Reichart Clayton , Sett Suvro , Seear Michael , Devine Dana 
Published: March 2018

SummaryWe have investigated hemostatic parameters including platelet activation in 56 pediatric patients with or without cyanosis undergoing cardiopulmonary bypass (CPB) and cardiac surgery to repair congenital defects. Patients were participants in a study assessing the effects of tranexamic acid on surgery-related blood loss. Parameters monitored included blood loss, prothrombin F1.2, thrombin-antithrombin complexes, t-PA, PAI-1, plasminogen, fibrin D-dimer, and plasma factor XIII. Additionally, flow cytometry monitored platelet degranulation (P-selectin or CD63), as well as surface-bound fibrinogen, von Willebrand factor and factor XIIIa. Cyanotic patients had evidence of supranormal coagulation activation as both fibrin D-dimer and PAI-1 levels were elevated prior to surgery. While the extent of expression of Pselectin or CD63 was not informative, platelet-associated factor XIIIa was elevated in cyanotic patients at baseline. In both patient groups, CPB altered platelet activation state and coagulation status irrespective of the use of tranexamic acid.
A New Candidate Missense Mutation (Leu 1657 Ile) in an Apparently Asymptomatic Type 2A (Phenotype IIA) von Willebrand Disease Family
Authors: Guilliatt A. M. , Surdhar G. K. , Theophilus B. D. M. , Hill F. G. H. , Enayat M. S. 
Published: March 2018

SummaryType 2A von Willebrand disease (VWD) is mostly an autosomal dominantly inherited bleeding disorder characterised by a qualitative defect of von Willebrand factor (VWF). Mutation screening was used to screen the whole of VWF gene followed by direct sequencing to detect the mutation in a father and son diagnosed with type 2A (phenotype IIA) von Willebrand disease. A C5219 to A transversion was detected predicting Leucine to Isoleucine substitution in codon 1657. This novel missense mutation which was also identified by MboI restriction enzyme analysis, was found in both patient and his father but not in any other unaffected family member or 50 unrelated normal individuals. This substitution was reproduced by in vitro site directed mutagenesis of full-length VWF cDNA and transiently expressed in COS-7 cells. The corresponding recombinant VWF protein exhibited the full spectrum of VWF multimers, suggesting that the abnormal multimer seen in the patient results from increased proteolysis.
Prothrombin Activation Is Increased among Asymptomatic Carriers of the Prothrombin G20210A and Factor V Arg506Gln Mutations
Authors: Humphries Steve , Smillie Belinda , Li Lily , Cooper Jacqueline , Barzegar Samad , Rosenberg Robert , Miller George , Bauer Kenneth 
Published: March 2018

SummaryThe risk of venous thrombosis is increased in individuals who carry specific genetic abnormalities in blood coagulation proteins. Among Caucasians, the prothrombin G20210A and factor V Arg506Gln (FV R506Q) mutations are the most prevalent defects identified to date. We evaluated their influence on markers of coagulation activation among participants in the Second Northwick Park Heart Study, which recruited healthy men (aged 50–61 years) from nine general medical practices in England and Wales. They were free of clinical vascular disease and malignancy at the time of recruitment. Genotypes for the two mutations were analyzed using microplate array diagonal gel electrophoresis, and coagulation markers (factor XIIa; activation peptides of factor IX, factor X, and prothrombin; fibrinopeptide A) were measured by immunoassay. Factor VII coagulant activity and factor VIIa levels were determined by a functional clotting assay. Among 1548 men genotyped for both mutations, 28 (1.8%) and 52 (3.4%) were heterozygous for prothrombin G20210A and FV R506Q, respectively. The only coagulation marker that was significantly associated with the two mutations was prothrombin activation fragment F1+2 [mean ± SD, 0.88 ± 0.32 nmol/L in men with prothrombin G20210A (p = 0.002) and 0.89 ± 0.30 in men with FV R506Q (p = 0.0001) versus 0.72 ± 0.24 among non-carriers for either mutation]. This data provides conclusive evidence that heterozygosity for the prothrombin G20210A as well as the FV R506Q mutations in the general population leads to an increased rate of prothrombin activation in vivo.