bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Antimitogenic Action of the Sulphated Polysaccharide Fucoidan Differs from Heparin in Human Vascular Smooth Muscle Cells
Authors: Mulloy Barbara , Gallagher Karen , O’Brien Leisha , Hughes Alun , Patel Mahendra 
Published: March 2018

SummaryThe sulphated polysaccharides fucoidan and heparin both inhibit vascular smooth muscle cell (VSMC) proliferation. In this study we compared their actions on mitogenesis and ERK1/ERK2 activation in human VSMC. Although they displaced cell surface [3H]-heparin binding with similar affinity, they exerted clearly distinguishable actions. Fucoidan potently inhibited DNA synthesis stimulated by foetal calf serum, PDGF-BB and thrombospondin-1. Heparin inhibited the mitogenic action of serum and thrombospondin-1 (though less potently than fucoidan), but failed to inhibit PDGF-BB-induced DNA synthesis. In parallel studies, fucoidan, but not heparin, inhibited ERK1/ERK2 activation by PDGF-BB. Moreover, fucoidan inhibited serum-induced mitogenesis in “heparin resistant” VSMC, which are refractory to heparin’s antimitogenic action. In summary, the structurally different polysaccharides, heparin, fucoidan (and fucans) have distinguishable effects on mitogenesis and ERK1/ERK2 activation, suggesting that different mechanism(s) mediate these actions. The potent antimitogenic action of fucoidan and its efficacy in heparin resistant VSMC emphasise the need to further investigate its mechanism of action in human VSMC and suggest this agent could have therapeutic potential.
Distribution of Th1- and Th2-induced Anti-factor VIII IgG Subclasses in Congenital and Acquired Hemophilia Patients
Authors: Lei Sijin , Lei Howard , Green Daid , Gill Joan , Conti-Fine Bianca , Reding Mark 
Published: March 2018

SummaryDevelopment of antibodies (Ab) that inhibit the procoagulant function of factor VIII (fVIII) seriously complicates the treatment of hemophilia A patients. It also causes acquired hemophilia, a rare yet serious autoimmune disease. The design of effective fVIII-specific tolerizing procedures will require elucidation of the role of the different CD4+ T cell subsets that drive inhibitor synthesis. To examine the contribution of Th1 and Th2 cells in the anti-fVIII Ab response, we measured the concentration of Th1- and Th2-driven anti-fVIII IgG subclasses in 17 patients with severe hemophilia A and 18 patients with acquired hemophilia. We found that both congenital and acquired hemophilia patients had similar and comparable proportions of Th1- and Th2-induced anti-fVIII Ab, suggesting a more important role of Th1 cells in the immune response to fVIII than previously appreciated. The distribution of anti-fVIII IgG subclasses was stable for periods of up to six months. More intense anti-fVIII Ab responses and higher inhibitor titers correlated with a predominance of Th2-driven subclasses. In contrast, Th1-driven anti-fVIII Ab were predominant in patients who had low anti-fVIII Ab concentrations, even when this was the result of successful immune tolerance or immunosuppressive therapy, which had caused drastic reduction or disappearance of inhibitors.Thus, synthesis of Th2-driven inhibitors occurs when the anti-fVIII Ab response is intense, while Th1 cells may be involved in the long-term maintenance of anti-fVIII Ab synthesis.
The Thrombogram in Rare Inherited Coagulation Disorders: Its Relation to Clinical Bleeding
Authors: Al Dieri Raed , Peyvandi Flora , Santagostino Elena , Giansily Muriel , Mannucci Pier Mannuccio , Schved Jean , Béguin Suzette , Hemker H. 
Published: March 2018

SummaryWe investigated the relation between clotting factor concentration, the parameters of the thrombin generation curve (the thrombogram) and the severity of clinically observed bleeding in patients with congenital deficiency of prothrombin (n = 21), factor V (n = 22), factor VII (n = 22), factor X (n = 10), factor XI (n = 7) and factor XII (n = 6). The parameters used were: area under the curve (endogenous thrombin potential, ETP), peak concentration of thrombin attained and lag time before manifest formation.Peak height and ETP varied linearly with the concentration of prothrombin. For the other factors these parameters hyperbolically approached to the 100% limit with increasing clotting factor concentration. Half normal ETP was seen at about the following concentrations: prothrombin (50%), factor V (1%), factor VII (2%), factor X (5%) and factor XI (1%). As a rule, the peak height was somewhat more sensitive to clotting factor decrease than the ETP was.In all the patients with severe bleeding symptoms the ETP was less than 20% of normal. Bleeding tendency was absent or mild in patients with an ETP of 30% or higher. This value (except for prothrombin) is already obtained at concentrations of clotting factor of 1%-2%, which corroborates the clinical observation that a severe bleeding tendency is only seen in severe clotting factor deficiencies (less than 1%). The one exception was a patient with factor VII deficiency and severe bleeding, who showed a normal ETP value, albeit with a decreased peak height and a prolonged lag-time.
Is APC Resistance a Risk Factor for Venous Thromboembolism in Patients over 70 Years?
Authors: Lacut Karine , Le Gal Grégoire , Van Dreden Patrick , Bressollette Luc , Scarabin Pierre-Yves , Leroyer Christophe , Mottier Dominique , Oger Emmanuel 
Published: March 2018

SummaryActivated protein C (APC) resistance is the most common risk factor for venous thromboembolism (VTE). Previous studies mostly analysed patients under 70 years and reported a four-to sevenfold increased risk. This case-control study included consecutive patients referred for a clinical suspicion VTE to our medical unit: 621 patients with a well-documented diagnosis (cases) and 406 patients for which the diagnosis was ruled out and who had no personal history of VTE (controls). APC resistance related to factor V Leiden was defined by either a positive DNA analysis or a positive STA® Staclot APC-R assay. Under 70 years, APC resistance was associated with a threefold increased risk of VTE (odds ratio 3.2, 95% CI, 1.7 to 6.0), whereas in patients over 70 years, it appeared to be no longer a strong risk factor (odds ratio 0.8, 95% CI, 0.4 to 1.7). Age appeared as an effectmeasure modifier with a significant interaction (p = 0.005). Our data suggest that APC resistance is not a risk factor for VTE in elderly.
Recombinant Nematode Anticoagulant Protein c2, a Novel Inhibitor of Tissue Factor-Factor VIIa Activity, Abrogates Endotoxin-Induced Coagulation in Chimpanzees
Authors: Moons Arno , Peters Ron , Cate Hugoten , Bauer Kenneth , Vlasuk George , Büller Harry , Levi Marcel 
Published: March 2018

SummarySystemic activation of coagulation leading to disseminated intravascular coagulation (DIC) is an important feature in patients with severe sepsis. Tissue factor has been shown to play a primary role in this pathological response, as revealed by the use of specific inhibitors and antagonists of the tissue factor/factor VIIa pathway. This class of agents has been demonstrated to attenuate the coagulation response in human volunteers with induced low-grade endotoxemia and to reduce mortality in primate models of Gram-negative sepsis. The efficacy of these agents in attenuating the activation of coagulation and formation of microvascular thrombosis in sepsis may depend on the mechanism of inhibition. Here we demonstrate the efficacy of recombinant nematode anticoagulant protein c2 (rNAPc2) that specifically inhibits the tissue factor/factor VIIa complex by a novel mechanism, in a model of endotoxin-induced coagulation activation in chimpanzees.Administration of a low dose of Gram-negative endotoxin induced marked increases of thrombin generation as measured by plasma levels of prothrombin activation fragment F1+2 and thrombin-antithrombin complexes, which were completely blocked by rNAPc2. In chimpanzees receiving rNAPc2 alone, there was a significant reduction in the activation of factor X but not factor IX, compared to animals receiving placebo. In contrast to the effect of rNAPc2 on thrombin generation, there was no effect of this inhibitor on the well known enhanced systemic fibrinolytic response induced by endotoxin.In conclusion, the recombinant peptide rNAPc2 is an effective inhibitor of tissue factor-driven thrombin generation during low grade endotoxemia. These results suggest that rNAPc2 may be a promising therapeutic option to inhibit coagulation activation in patients with sepsis.
Analysis of the Amino Acid Requirement for a Normal αIIbβ3 Maturation at αIIbGlu324 Commonly Mutated in Glanzmann Thrombasthenia
Authors: Milet-Marsal Sandrine , Breillat Christelle , Peyruchaud Olivier , Nurden Paquita , Combrié Robert , Bourre François , Nurden Alan 
Published: March 2018

SummaryGlanzmann thrombasthenia is an inherited bleeding disorder arising from quantitative or qualitative defects of the αIIbβ3 integrin of platelets. Here, we report that PCR-SSCP analysis and DNA sequencing revealed a homozygous single base pair substitution in exon 12 of the αIIb gene leading to a Glu324 (E) to Lys (K) substitution in the αIIb subunit in a patient with Type I disease. As this mutation is found on at least 3 continents, the codon for Glu324 may be a mutational hotspot of the disease. To better understand this mutation, we analyzed the effect of substituting E324 with A324, L324, D324, Q324, N324, S324, as well as K324, looking at both αIIbβ3 maturation and cell surface expression in transiently transfected Cos-7 cells. The maturation state of the receptor clearly correlated with the level of cell membrane expression. Maturation efficiency was dependent on the electric charge as well as the size of the side chain of the amino acid present in what is a highly conserved N-terminal position in the third β-strand of blade 5 of the αIIbβ-propeller.
The Mucin-like Macroglycopeptide Region of Glycoprotein Ibα is Required for Cell Adhesion to Immobilized von Willebrand Factor (VWF) Under Flow but not for Static VWF Binding
Authors: Li Chester , Dong Jing-fei , López José 
Published: March 2018

SummaryA dominant feature of the structure of platelet glycoprotein (GP) Ibα, the von Willebrand factor (VWF)-binding subunit to the GP IbIX-V complex, is the presence of an elongated, heavily glycosylated mucin-like stalk between the plasma membrane and the N-terminal 45-kDa ligand-binding domain. Here, we investigated the function of that region by expressing a mutant lacking residues 318-452 as part of a recombinant GP Ib-IX complex. We studied the VWF-binding function of this mutant under both static conditions and flow. The mutant GP Ibα was expressed normally on the surface of CHO bIX cells (stably expressing GP Ibβ and GP IX) and the proper conformation of the ligand-binding region was verified by the normal binding of 5 conformation-sensitive monoclonal antibodies. Under static conditions, cells expressing mutant GP Ibα bound VWF (binding induced by either botrocetin or ristocetin) in a manner indistinguishable from cells expressing wild-type GP Ibα. We also evaluated the ability of the mutant to mediate cell adhesion to immobilized VWF in the presence of fluid shear stress (at 2 and 10 dyn/cm2). When the mutant-expressing cells were incubated with immobilized VWF for 1 min before being exposed to shear, they rolled on the VWF surface in a manner similar to wild-type cells. However, if the cells were not first allowed to settle on the surface before the application of shear stress, the mutant GP Ibα was unable to capture the cells onto the VWF surface from the fluid stream, an indication that steric hindrance from other cell surface molecules may prevent access of the GP Ibα ligand-binding site to the surfaceimmobilized VWF.
Acquired Activated Protein C Resistance Associated with Anti-Protein S Antibody as a Strong Risk Factor for DVT in Non-SLE Patients
Authors: Kuratsune Hirohiko , Suehisa Etsuji , Kawasaki Tomio , Machii Takashi , Kitani Teruo , Iwatani Yoshinori , Kanakura Yuzuru , Nojima Junzo 
Published: March 2018

SummaryAnti-phospholipid (aPL) antibodies (Abs) are well known to be associated with thromboembolic events in patients with systemic lupus erythematosus (SLE). However, the clinical relevance of aPL Abs in patients without SLE (non-SLE) who have venous thromboembolism remains unclear. We evaluated 143 non-SLE patients with a first episode of clinically suspected deep vein thrombosis (DVT) by using objective tests for diagnosing DVT and laboratory tests including the activated protein C resistance (APC-R) test, the factor V Leiden test, and various aPL Abs. The prevalence of acquired APC-R, in which case there was no factor V Leiden mutation, was significantly higher in patients with DVT (15/58 cases, 25.9%, p <0.0001) than in those without DVT (3/80 cases, 3.7%), and confirmed that acquired APC-R was a strong risk factor for DVT (odds ratio [OR], 8.95; 95% confidence intervals [CI], 2.45-32.7; p <0.001). Multivariate logistic analysis revealed that the presence of LA, aCL, anti- β2-glycoprotein I, anti-prothrombin and anti-protein C Abs was not reliable as a risk factor for DVT in non-SLE patients, and that the presence of anti-protein S Abs was the most significant risk factor for DVT (OR, 5.88; 95% CI, 1.96-17.7; p <0.002). Furthermore, the presence of anti-protein S Abs was strongly associated with acquired APC-R (OR, 57.8; 95% CI, 8.53-391; p <0.0001). These results suggest that acquired APC-R may reflect functional interference by anti-protein S Abs of the protein C pathway, which action may represent an important mechanism for the development DVT in non-SLE patients.
Interaction Between Hyperhomocysteinemia, Mutated Methylenetetrahydrofolatereductase (MTHFR) and Inherited Thrombophilic Factors in Recurrent Venous Thrombosis
Authors: Keijzer Miranda , Blom Henk , Bos Gerard , Willems Huub , Gerrits Wim , Rosendaal Frits , den Heijer Martin 
Published: March 2018

SummaryVenous thrombosis is a multicausal disease involving acquired and genetic factors. In this study we investigated a possible interaction between hyperhomocysteinemia (fasting or postload) and factor V Leiden or prothrombin G20210A on the risk of recurrent venous thrombosis. We also looked at the risk due to mutations in the MTHFR-gene (C677T and A1298C).We performed a case-control study in 171 patients with a history of recurrent venous thrombosis and 461 control subjects from the general population. Hyperhomocysteinemia (fasting or 6 h after an oral methionine load) was defined as a homocysteine concentration above the 90th percentile of the distributions in the control group.The odds ratio (adjusted for age and sex) for recurrent venous thrombosis was 1.8 (95%CI: 1.1 to 3.0) for fasting hyperhomocysteinemia, 5.1 (95%CI: 3.0 to 8.6) for factor V Leiden and 1.8 (95%CI: 0.7 to 4.2) for prothrombin G20210A. We found 14 patients and 3 controls with both hyperhomocysteinemia and factor V Leiden, which yielded an odds ratio of 11.6 (95%CI: 3.2 to 42.5). We found no interaction between hyperhomocysteinemia and prothrombin G20210A. The relative risk for MTHFR 677CT was 1.6 (95%CI: 1.1 to 2.4) and for MTHFR 677TT was 1.4 (95%CI: 0.7 to 2.8). The combined risk for MTHFR 677TT and factor V Leiden was 18.7 (95%CI: 3.3 to 108).We conclude that hyperhomocysteinemia and factor V Leiden are risk factors for recurrent venous thrombosis. The risk of thrombosis appeared high for individuals who had both risk factors.
Anti-β2-Glycoprotein I and Anti-Prothrombin Antibodies in Antiphospholipid-Negative Patients with Thrombosis
Authors: Previtali Sara , Barbui Tiziano , Galli Monica 
Published: March 2018

SummaryWe performed a case-control study to assess whether anti-β2-glycoprotein I and anti-prothrombin antibodies are independent risk factors of thrombosis. Cases were 79 patients with arterial and/or venous thrombosis without lupus anticoagulants, anticardiolipin antibodies and systemic lupus erythematosus; controls were 85 normal subjects. The prevalences and titers of IgG and IgM anti-β2-glycoprotein I and antiprothrombin antibodies were similar in both groups. Cases were analyzed with respect to the arterial or venous type of thrombosis and to the presence of congenital or acquired risk factors for thrombosis: no statistically significant relationships with the presence of anti-β2glycoprotein I and anti-prothrombin antibodies were found. Our data indicate that anti- β2-glycoprotein I and anti-prothrombin antibodies are not risk factors for thrombosis independent of lupus anticoagulants and anticardiolipin antibodies. Their measurement, therefore, is not warranted in the laboratory screening of patients with arterial and/or venous thrombosis.
Polymorphic Changes in the 5’ Flanking Region of Factor VII Have a Combined Effect on Promoter Strength
Authors: Kudaravalli Rama , Tidd Theresa , Pinotti Mirko , Ratti Antonia , Santacroce Rosa , Margaglione Maurizio , Dallapiccola Bruno , Bernardi Francesco , Fortina Paolo , Devoto Marcella , Pollak Eleanor 
Published: March 2018

SummaryPolymorphic differences in the 5’ flanking region of the gene encoding procoagulant protein Factor VII (FVII) are associated with variations in FVII coagulant activity (FVII:C) and FVII antigen (FVII:Ag) levels. A decanucleotide insert polymorphism (CCTATATCCT) at 323 bp upstream of the start site of translation correlates with a decrease of approximately 20% FVII:C levels per allele containing this insert. However, linkage disequilibrium of the decanucleotide polymorphism with two single nucleotide polymorphisms (SNPs) at –122 and –401 have made it difficult to pinpoint the functional role, if any, of these genetic changes in lowering FVII levels. In vitro reporter gene studies in HepG2 cells analyzing the 8 possible combinations of polymorphic sites at –401, –323, and –122 reveal the necessity of the presence of the three concurrent polymorphic changes to maximally decrease promoter strength. In addition, these in vitro results are supported by in vivo studies in 89 individuals of African heritage, 34% of whom display a new haplotype that shows the polymorphic changes at -323 and -401 but lacks the change at -122.
Platelet Aggregation and Activation under Complex Patterns of Shear Stress
Authors: Zhang Jian-ning , Bergeron Angela , Yu Qinghua , Sun Carol , McIntire Larry , López José , Dong Jing-fei 
Published: March 2018

SummaryArterial stenosis results in a complex pattern of blood flow containing an extremely fast flow in the throat of stenosis and a post-stenosis low flow. The fast flow generates high shear stress that has been demonstrated in vitro to activate and aggregate platelets. One potential problem of these in vitro studies is that platelets are invariably exposed to a high shear stress for a period that is significantly longer than they would have experienced in vivo. More importantly, the role of the poststenosis low flow in platelet activation and aggregation has not been determined. By exposing platelets to a shear profile that contains both high and low shear segments, we found that platelets aggregate when they are exposed to a high shear stress of 100 dyn/cm2 for as short as 2.5 s, a period that is significantly shorter than those previously reported (30–120 s). Platelet aggregation under this condition requires a low shear exposure immediately after a high shear pulse, suggesting that post-stenosis low flow enhances platelet aggregation. Furthermore, platelet aggregation under this condition is not activation-dependent because the CD62P expression of sheared platelets is significantly less than that of platelets treated with ADP. Based on these findings, we propose that shear-induced platelet aggregation may be a process of mechanical crosslinking of platelets, requiring minimal platelet activation. This process may function as a protective mechanism to prevent in vivo irreversible platelet activation and aggregation under temporary high shear.
Blockade of Platelet GPIIB-IIIA (Integrin αIIbβ3) in Flowing Human Blood Leads to Passivation of Prothrombotic Surfaces
Authors: Riederer Markus , Ginsberg Mark , Steiner Beat 
Published: March 2018

SummaryWe examined the impact of platelet activation on platelet adhesion to collagen in flowing human blood. ADP activation of platelets in ex vivo flowing blood resulted in paradoxical inhibition of platelet deposition on collagen. Blockade of fibrinogen binding to platelets by Lamifiban, a competitive antagonist of GPIIb-IIIa (integrin αIIbβ3), reversed this inhibition, leading to a marked increase in integrin α2β1-dependent platelet adhesion. Analysis of integrin α2β1-dependent platelet adhesion to collagen indicated that ADP-induced suppression of platelet adhesion is the result of trans-dominant inhibition of integrin α2β1 caused by fibrinogen binding to integrin GPIIb-IIIa. Lamifiban blocked fibrinogen binding, reversing the trans-dominant inhibition of α2β1 dependent adhesion to collagen. The GPIIb-IIIa antagonist resulted in the formation of a nonthrombogenic, passivated surface comprised of an adherent platelet monolayer. This unexpected consequence of blocking fibrinogen binding to GPIIb-IIIa may explain the long-term benefits of short-term GPIIb-IIIa antagonist treatment of Acute Coronary Syndrome patients.
Regulation by Nitric Oxide of Endotoxin-Induced Tissue Factor and Plasminogen Activator Inhibitor-1 in Endothelial Cells
Authors: Pérez-Ruiz Ana , Montes Ramón , Velasco Francisco , López-Pedrera Chary , Páramo José , Orbe Josune , Hermida José , Rocha Eduardo 
Published: March 2018

SummaryThe increase in nitric oxide (NO) production in lipopolysaccharide (LPS)-induced sepsis is thought to contribute to the development of shock. However, NO could also play an antithrombotic role. Little is known about the modulating effect of NO on the endothelial overexpression and production of tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) occurring in endotoxemia. We analyzed the effect of N(G)-nitro-L-arginine-methyl-ester (L-NAME), an inhibitor of NO synthases, and S-nitroso-N-acetyl-D,L-penicillamine (SNAP), a NO donor, on the expression and synthesis of TF and PAI-1 by LPS-challenged human umbilical vein endothelial cells (HUVEC): L-NAME enhanced the increase in TF mRNA and antigen levels (P <0.05) observed in LPS-treated HUVEC; SNAP down-regulated the LPSinduced TF increment (p <0.05). However, no effects of NO on regulation of the LPS-dependent increase in PAI-1 could be seen. Thus, NO could play an antithrombotic role in sepsis by down-regulating the endothelial overexpression and production of TF.
Thrombinography shows acquired resistance to activated protein C in patients with lupus anticoagulants
Authors: Regnault Véronique , Béguin Suzette , Wahl Denis , de Maistre Emmanuel , Coenraad Hemker H. , Lecompte Thomas 
Published: March 2018

SummaryIn patients with lupus anticoagulants (LA), acquired resistance to activated protein C (APC) is difficult to demonstrate with clot-based assays due to the presence of the anticoagulant. Via the conversion of a fluorogenic substrate (thrombinography), we monitored the complete process of thrombin formation and decay and its delimitation by the protein C system in eight consecutive LA-patients without anticoagulant therapy and non-carriers of the V Leiden polymorphism. Thrombin generation was triggered in platelet-poor and platelet-rich plasma by recalcification in the presence of a low concentration of tissue factor.In 7 out of 8 patients we observed a long lag-time before the thrombin burst (LA effect) together with a marked inability of APC to diminish the thrombin activity. The lag-phase was however prolonged to some degree by APC. The effects were more outspoken in the presence of phospholipids from patients' platelets than with added phospholipids.Thrombinography thus demonstrates APC resistance in LA-patients despite the occurrence of long lag-times (clotting times). The amount of thrombin activity generated in the presence of APC could be a better indicator of the thrombotic risk than the moment at which the thrombin burst starts.