bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intravenous Immunoglobulin Mediates an Increase in Anti-Platelet Antibody Clearance via the FcRn Receptor
Authors: Hansen Ryan , Balthasar Joseph 
Published: March 2018

SummaryWe have recently shown that intravenous immunoglobulin (IVIG) therapy leads to an increased rate of anti-platelet antibody clearance in an animal model of immune thrombocytopenia. The present study was performed to confirm the importance of the FcRn receptor in mediating this effect of IVIG. The pharmacokinetics of an anti-platelet antibody, 7E3, were studied in mice lacking expression of FcRn and in control mice, both in the presence and absence of IVIG. IVIG increased the clearance of 7E3 in mice with functioning FcRn receptors, with an average clearance value of 14.4 ± 1.4 ml/d/kg in IVIG treated mice vs. 5.2 ± 0.3 ml/d/kg in controls (P <0.001). In mice lacking expression of FcRn, IVIG treatment did not increase 7E3 clearance (61.0 ± 3.6 ml/d/kg vs. 71.5 ± 4.0 ml/d/kg in controls). Thus, these data support the hypothesis that IVIG increases antibody elimination via saturation of FcRn.
Thrombin binding to GPIbα induces platelet aggregation and fibrin clot retraction supported by resting αIIbβ3 interaction with polymerized fibrin
Authors: Dubois Christophe , Steiner Beat , Kieffer Nelly , Meyer Reigner Sylvie 
Published: March 2018

SummaryWe have investigated the mechanisms leading to platelet aggregation following thrombin interaction with the glycoprotein (GP) Ib-IX-V complex. We show that platelets desensitized for the two thrombin receptors, PAR-1 and PAR-4, are still able to aggregate in response to thrombin and that this aggregation can be inhibited by a monoclonal antibody (VM16d) that blocks thrombin binding to GPIbα, or by pretreatment of platelets with Mocarhagin, a protease that specifically cleaves GPIbα. The thrombin/GPIbα-initiated signaling cascade induces platelet shape change through activation of the Rho kinase p160ROCK, independent of calcium mobilization, transient MEK-1 phosphorylation as well as the cleavage of talin through a calcium-independent mechanism. This signaling cascade does not induce the exposure of high affinity αIIbβ3 integrin receptors, nor does it lead to µ-calpain cleavage of filamin or the integrin cytoplasmic tail. In contrast, we provide evidence that binding of thrombin to GPIbα induces fibrin binding to resting αIIbβ3 leading to fibrin-dependent platelet aggregation and clot retraction, that can be selectively inhibited by αIIbβ3 antagonists such as RGDS, the dodecapeptide or lamifiban, as well as by the fibrin polymerization inhibitor GPRP-amide.
Ruling out clinically suspected pulmonary embolism by assessment of clinical probability and D-dimer levels: a management study
Authors: Lutisan Johan , Marwijk Kooy Marinus , Kuipers Bart , Oostdijk Ad , van der Leur Jef , Büller Harry , Leclercq Monique 
Published: March 2018

SummaryD-dimer test combined with clinical probability assessment has been proposed as the first step in the diagnostic work-up of patients with suspected pulmonary embolism (PE). In a prospective management study we investigated the safety and efficiency of excluding PE by a normal D-dimer combined with a low or moderate clinical probability. Of the 202 study patients this combination ruled out PE in 64 (32%) patients. The 3-month thromboembolic risk in these patients was 0% (95% CI, 0.0-5.6%).The prevalence of PE in the entire cohort was 29% (59 patients), whereas in the low, moderate and high clinical probability groups this was 25%, 26% and 50%, respectively. We conclude that ruling out suspected PE by a normal D-dimer combined with a low or moderate clinical probability appears to be a safe and efficient strategy. The accuracy of the clinical probability assessment is modest.
Angiogenesis: molecular mechanisms and functional interactions
Authors: Breier Georg , Augustin Hellmut 
Published: March 2018

SummaryThe German Priority Research Program “Angiogenesis” (www.angiogenese.de) hosts a biannual meeting in the Kloster Seeon in Southern Germany. The 2nd Kloster Seeon Meeting “Angiogenesis: Molecular Mechanisms and Functional Interactions” was held in September 2002. It included sessions on hypoxia, the biology of endothelial precursor cells, angiogenic growth factors including VEGFs, the angiopoietins, ephrins, and FGFs, mechanisms of vascular sprouting and cell-cell contacts during angiogenesis, angiogenic signaling, lymphangiogenesis, angiogenesis during tumor invasion and metastasis, and on novel angiomanipulatory therapies. This report summarizes the key findings reported during the platform presentations of the meeting.
Oxysterols suppress constitutive fibrinogen expression
Authors: Xia Hui , Redman Colvin 
Published: March 2018

SummaryElevated levels of both fibrinogen and cholesterol are risk factors in coronary artery disease. Previously we reported a metabolic link between fibrinogen and lipid metabolism in that HepG2 cells that were programmed by transfection of Bβ-fibrinogen cDNA to overexpress fibrinogen exhibited increased synthesis of cholesterol and increased secretion of apolipoprotein B. In this study we demonstrate that oxysterols, which participate in maintaining cholesterol homeostasis, also down regulate fibrinogen expression. Treatment of HepG2 cells with 25-hydroxycholesterol lowered fibrinogen Aα, Bβ and γ mRNA levels and inhibited fibrinogen synthesis and secretion but had no effect on α1-antitrypsin which, like fibrinogen, is an acute-phase protein. The inhibition of fibrinogen synthesis by oxysterols was maintained in interleukin-6 treated cells. Other oxysterols, that inhibit cholesterol synthesis by a feedback mechanism, also diminished fibrinogen expression in HepG2, rat H-4-II-E hepatoma cells and in primary human hepatocytes. Overexpression of SREBP-1 and SREBP-2 by transfection of HepG2 cells, or treatment with a synthetic LXRα agonist, which affect cholesterol metabolism, did not affect fibrinogen expression. We conclude that fibrinogen and cholesterol may share a novel common regulatory pathway.
Elucidation of the epitope of a latency-inducing antibody: identification of a new molecular target for PAI-1 inhibition
Authors: Naessens Dominik , Gils Ann , Compernolle Griet , Declerck Paul 
Published: March 2018

SummaryThe monoclonal antibody MA-33B8, directed against the serpin plasminogen activator inhibitor-1 (PAI-1), has unique functional properties as it induces acceleration of the active-to-latent transition (Verhamme I et al. J Biol Chem 274: 17511-7, 1999), resulting in PAI-1 activity neutralization. In this study, we have identified Lys88, Asp89, Lys176 and His229 as the major residues of the conformational epitope. Lysine88 and aspartic acid89, contributing the most, are located on the loop between α-helix D and β-strand 2A. Strikingly, these residues undergo dramatic conformational changes during latency conversion. The three-dimensional localization of this epitope and its differential exposure in active and latent forms of PAI-1 provide a molecular explanation for the underlying mechanism of MA-33B8. Rearrangements of hydrogen bonds in this region upon latency transition, strongly suggest that binding of MA-33B8 may result in the generation of energy required in the rate-limiting step of latency transition. Thus, this novel epitope reveals a new interaction site in PAI-1 as a putative molecular target to modulate PAI-1 activity.
Course of indicators of thrombin activity in the early phase of acute myocardial infarction: effect of fibrinolytic therapy and acute percutaneous coronary angioplasty
Authors: Kaden Jens , Haase Karl , Borggrefe Martin , Dempfle Carl-Erik 
Published: March 2018

SummaryWe evaluated assay systems for detection of in vivo thrombin activity in patients with acute myocardial infarction. The study included 31 consecutive patients with acute myocardial infarction treated either with fibrinolytic therapy (FLT), or acute PTCA. Blood samples were drawn at admission, after 30 min, 1 h, 3 h, 6 h, 12 h, 24, and 48 h. Assays related to the enzymatic action of thrombin included fibrinopeptide A ELISA, a novel latex-enhanced photometric immunoassay for soluble fibrin complexes, fibrin monomer antigen, D-dimer antigen, and soluble platelet glycoprotein V, which is released from the platelet surface by thrombin cleavage.The soluble fibrin assay displayed a high degree of correlation with fibrinopeptide A, and no correlation with D-dimer antigen, indicating that this parameter allows monitoring of in vivo thrombin activity in patients with acute myocardial infarction. Fibrin monomer antigen, and D-dimer antigen, were influenced by FLT, indicating cross-reactivity with proteolytic fragments of fibrin. No significant changes in soluble glycoprotein V were observed.The results show that the novel soluble fibrin assay appears to be a promising method for measurement of in vivo fibrin formation in patients with acute myocardial infarction, irrespective of the primary treatment decision for FLT or acute PTCA.
Homozygosity for the Protein S Heerlen Allele Is Associated with Type I PS Deficiency in a Thrombophilic Pedigree with Multiple Risk Factors
Authors: Espinosa-Parrilla Yolanda , Navarro Gemma , Morell Marta , Abella Eugènia , Estivill Xavier , Sala Núria 
Published: March 2018

SummaryThe multifactorial character of thrombotic disease is shown in a Spanish pedigree in which the propositus, with recurrent deep vein thrombosis, inherited the factor V R/Q506 mutation, the prothrombin 20210G/A variant and type III Protein S deficiency. Among 14 relatives carrying one or two of these three risk factors, thrombosis is present in a heterozygote for R/Q506 and in another for 20210G/A, who also had slightly positive antiphospholipid antibodies. Type I PS deficiency was also found in a young asymptomatic woman. PROS1 analysis showed coexistence of type III and type I PS deficiency to be associated with heterozygosity and homozygosity, respectively, for the P460 or PS Heerlen allele of the S/P460 variant. Analysis of PS values in this and other pedigrees segregating this variant revealed that not only free but also mean total PS levels are slightly but significantly lower in the SP460 heterozygotes than in the SS460 homozygotes. These findings strongly suggest a role of the P460 variant in the expression of the PS deficient phenotype.
A Reliable and Reproducible ELISA Method to Measure Ristocetin Cofactor Activity of von Willebrand Factor
Authors: Vauterin Stephan , Schlammadinger Agota , Mazurier Claudine , Deckmyn Hans , Vanhoorelbeke Karen , Cauwenberghs Nancy 
Published: March 2018

SummaryThe ristocetin induced binding of vWF to GPIb, which is routinely tested in a platelet agglutination assay, can be reproducibly studied in an ELISA where plasma vWF binds to a captured rGPIbα-fragment (His1-Val289) in the presence of ristocetin. This binding is specific since the vWF-GPIb interaction could (i) be blocked by inhibitory antiGPIb or anti-(vWF A1 domain) monoclonal antibodies (mAbs) and (ii) be enhanced by an anti-vWF mAb that also facilitates ristocetin induced platelet agglutination. Further studies were undertaken to determine whether the test could be used to differentiate vWF from patients with different types of von Willebrand’s disease. The median vWF:RiCof activity in controls (n = 24) was 0.75 U/ml, in type 1 vWD patients (n = 17) 0.28 U/ml, in type 2A (n = 18) 0.055 U/ml, in type 2B (n = 4) 0.094 U/ml and in type 3 (n = 3) <0.0005 U/ml. Moreover, the values correlated well with those obtained from the vWF:RiCof-agglutination assay (r = 0.873). The vWF:RiCof-ELISA has several advantages: the use of a recombinant fragment instead of donor platelets results in a more reproducible test with a low inter-and intra-assay variability (<14% CV), the test can further be readily automated and for a single determination, only minimal amounts of patient plasma are required (8 µl).
Glycoprotein Ib-binding Protein from the Venom of Deinagkistrodon acutus – cDNA Sequence, Functional Characterization, and Three-Dimensional Modeling
Authors: Chen Yuh-Ling , Tsai Kuo-Wei , Chang Tschining , Hong Tse-Ming , Tsai Inn-Ho 
Published: March 2018

SummaryAgkicetin-C, a potent glycoprotein Ib antagonist from the venom of the Chinese pit viper, Deinagkistrodon acutus, has been purified and characterized (5). It is a disulfide-linked heterodimer containing subunits of 132 and of 123 amino acid residues. Herein, the complete amino acid sequences were resolved by cloning and nucleotide sequencing of the cDNAs. The sequences of its subunits are homologous to those of other snake venom proteins of the C-type (Ca2+-dependent) lectin superfamily. A three-dimensional model of agkicetin-C was constructed based on the crystal structure of habu coagulation factor IX/X-binding protein. By careful alignment of all the related sequences available and comparing the 3D-model of agkicetin-C with structures of other homologous proteins of different functions, some variable residues of agkicetin-C were identified, which possibly are responsible for the specificity of this distinct subtype of the C-type lectin-like venom proteins.
The Effect of Monoclonal Anti-human-platelet Antibodies on Platelet Kinetics in a Baboon Model: IgG Subclass Dependency
Authors: Pieters Henry , van Wyk Veronica , Cooper Susan , Roodt Jan , De Reys Stefan , Badenhorst Philip , Coetzee Lindi-Marie 
Published: March 2018

SummaryWe assessed the in vivo effect of six intact anti-human antiplatelet antibodies of two major IgG subclasses on platelet kinetics in baboons. Five of the six antibodies tested caused thrombocytopenia of varying degree when injected at a precalculated threshold value. An agglutinating IgG1 antibody (MA-8L4A12) caused a long-lasting, mild thrombocytopenia with a predominant uptake of radiolabelled platelets in the spleen, while the four IgG2 antibodies tested (MA-13G8E1, MA-2M5A6, MA-21K2E8 and MA-22M10) caused a severe, transient thrombocytopenia with uptake of platelets in the liver. Two of the IgG2 antibodies (MA-13G8E1 and MA-2M5A6) caused platelet activation and aggregation in vitro, whilst the other two did not elicit a platelet aggregation response. The platelet survival time was shortened with all five of the thrombocytopenia-inducing antibodies, while only one antibody (MA-2M5A6) had a significant effect on the bleeding time. This study indicates that the IgG subclasss may be a determining factor in the outcome of platelet sequestration in immune-induced thrombocytopenia.
Measurement of Tissue Factor Activity in Whole Blood
Authors: Santucci Richard , Erlich Jonathan , Labriola Joanne , Wilson Mark , Kao K. , Kickler Thomas , Spillert Charles , Mackman Nigel 
Published: March 2018

SummaryHigh circulating levels of the procoagulant molecule tissue factor (TF) are associated with thrombosis in a variety of diseases including unstable angina, cancer, and sepsis. Currently, there are no clinical assays to measure the level of TF activity in whole blood. We present an assay called Tissue Factor Clotting Time (“TiFaCT™”) that detects fibrin formation in human blood. The mean baseline clotting time in a healthy population was 472 ± 94 s (mean ± SD, n = 150). Bacterial lipopolysaccharide (LPS or endotoxin) shortened the clotting time in a time-dependent manner. Inhibitory anti-TF antibodies prolonged the clotting time of LPS-stimulated blood, indicating that the shortened clotting time was due to induction of TF expression. Patients with unstable angina had shortened mean baseline clotting time (284 ± 86, n = 13) compared with healthy volunteers (474 ± 98, n = 30), suggesting that these patients had elevated levels of circulating TF. The TiFaCT assay should prove clinically useful in quantifying the levels of circulating TF in patients at risk of thrombosis.
Improvement of Walking Distance by Defibrotide in Patients with Intermittent Claudication
Authors: Marubini E. , Coccheri S. , Nenci G. G. , Violi F. 
Published: March 2018

SummaryDefibrotide is an antithrombotic drug which enhances prostacyclin production and activates fibrinolytic system. The aim of this study was to investigate the improvement of walking distance in patients with intermittent claudication treated with defibrotide.DICLIS was a double blind, placebo-controlled study which included patients with walking distance autonomy at a standardized treadmill test ≤350 ≥100 meters. A total of 310 patients were randomly allocated to placebo (n = 101), defibrotide 800 mg/day (n = 104) or defibrotide 1200 mg/day (n = 105).During a one year follow-up, the Absolute Walking Distance (AWD) was measured six times (0, 30, 60, 90, 180, 360 days).Similar improvement in walking distance was found in the three groups until the 90th day; thereafter placebo group showed no further increase, while AWD continued to increase in the defibrotide groups. Between the 180th and 360th day visits, AWD was significantly higher (P <0.01) in patients given defibrotide than in patients given placebo. No difference in efficacy was observed between the two dosages of defibrotide. No differences in side effects were observed among the three groups.The results of the present trial suggest that long-term administration of defibrotide improves walking distance in patients with intermittent claudication.
Abbreviations: DICLIS = Defibrotide Intermittent CLaudication Italian Study, AWD = Absolute Walking Distance, IC = Intermittent Claudication, PVD = Peripheral Vascular Disease, LVOCF = Last Valid Observation Carried Forward, ITT = Intention-To-TreatAppendix, please see p. 676.
Decreased Sialic Acid Content of Plasma von Willebrand Factor in Precapillary Pulmonary Hypertension
Authors: de Souza Bruno , Maeda Nair , Lopes Antonio 
Published: March 2018

SummaryIn pulmonary hypertension, defective von Willebrand factor protein (vWF) lacking large multimers is present in circulation. This is associated with evidence of chronic endogenous platelet activation. Since asialo vWF has been shown to promote platelet activation and aggregation, we decided to investigate possible changes in the sialic acid content of plasma vWF in patients with precapillary pulmonary hypertension. vWF-associated sialic acid was measured indirectly as a wheat germ agglutinin-reactive substance (WGA-RS, Western blotting), and directly, as a thiobarbituric acid-reactive substance (TBA-RS, spectrophotometric reading). In the sixteen patients we studied (ages 8–45 yr), circulating vWF concentration was 2.18 times normal (p <0.001). However, patient vWF subunit contained 19% (WGA-RS) to 24% (TBA-RS) less sialic acid than the normal protein (p <0.05 for both determinations). In five patients, vWF-associated sialic acid was below 50% normal. We conclude that circulating vWF is hyposialylated in precapillary pulmonary hypertension and speculate that this might influence its interaction with platelets in vivo in these patients.
Major Structural Defects in the Antithrombin Gene in Four Families with Type I Antithrombin Deficiency
Authors: Beauchamp N. J. , Makris M. , Preston F. E. , Peake I. R. , Daly M. E. 
Published: March 2018

SummaryThe molecular basis of quantitative antithrombin deficiency was investigated in four families predicted to have major antithrombin gene rearrangements. A 1,442 bp deletion and insertion of the sequence 5’T(n = 38-40)GAGACG was characterised in one case. Sequence surrounding the breakpoints contained two perfect, and one imperfect, inverted repeats which may have mediated formation of a stem loop structure on one strand during DNA replication potentiating the deletion. A 9,219 bp deletion spanning introns 2 to 5 was identified in a second family. The identical 6 bp sequence was upstream of each breakpoint and the 5’ breakpoint was located in a sequence of the Alu 3 repeat predicted to be susceptible to strand breakage during transcription. This may have promoted misalignment, and deletion, of one of the repeats and the intervening DNA. A novel 1.8 kb antithrombin gene fragment was present in DNA digests from affected members of the third family suggesting a partial antithrombin gene duplication event while in the remaining family, evidence supporting a complete gene deletion was obtained.
Macrophages Synthesize Factor X and Secrete Factor X/Xa-containing Prothrombinase Activity into the Surrounding Medium
Authors: Lunderius Carolina , Tomasini-Johansson Bianca , Pejler Gunnar 
Published: March 2018

SummaryActivation of the coagulation cascade, mediated by various monocyte/macrophage procoagulants, is an important component in the pathology of inflammatory disease. The type of procoagulant expressed may vary between different monocyte/macrophage subtypes and may differ depending on how the cells are treated. In the present study we show that both murine peritoneal macrophages and human adherent synovial cells from rheumatoid arthritis lesions express prothrombinase activity that was inhibited by anti-Factor X antibodies. Northern blot analysis showed that Factor X was transcribed by the murine peritoneal cells and Western blot analysis showed the presence of Factor X antigen. Further experiments showed that the prothrombinase activity was secreted by the cells into the medium in a detergent-sensitive form, suggesting that the prothrombinase is released on small lipid-containing vesicles.
Increased Risk of Recurrent Venous Thromboembolism during Hormone Replacement Therapy
Authors: Qvigstad Erik , Arnesen Harald , Larsen Stig , Wickstrøm Egil , Sandset Per , Høibraaten Else 
Published: March 2018

SummaryRecent observational studies suggest a 2-4 fold increased risk of venous thromboembolism (VTE) in women taking hormone replacement therapy (HRT). The present study was started before publication of these studies, and the aim was to determine if HRT alters the risk of VTE in high risk women. The study was a randomized, double-blind, and placebo-controlled clinical trial with a doubletriangular sequential design. Females with previously verified VTE were randomized to 2 mg estradiol plus 1 mg norethisterone acetate, 1 tablet daily (n = 71) or placebo (n = 69). The primary outcome was recurrent deep venous thrombosis (DVT) or pulmonary embolism (PE). Between 1996 and 1998 a total of 140 women were included. The study was terminated prematurely based on the results of circumstantial evidence emerging during the trial. Eight women in the HRT group and one woman in the placebo group developed VTE. The incidence of VTE was 10.7% in the HRT group and 2.3% in the placebo group. In the HRT group, all events happened within 261 days after inclusion. The sequential design did not stop the study, but strongly indicated a difference between the two groups. Our data strongly suggests that women who have previously suffered a VTE have an increased risk of recurrence on HRT. This treatment should therefore be avoided in this patient group if possible. The results also support those of recent epidemiological studies, which also indicate increased risk of VTE in non-selected female populations during HRT.