bluuebunny/crossref_metadata_2025_split huggingface dataset:
Homozygous 2bp Deletion in the Human Factor VII Gene: A Non-Lethal Mutation that Is Associated with a Complete Absence of Circulating Factor VII
Authors: Mannucci Pier , Jenkins P. , Lee Anselm , Coppola Raffaella , Perry David , Peyvandi Flora 
Published: March 2018

SummaryWe report the case of a 5-year-old boy with severe factor VII deficiency. The affected child presented at the age of 8 months and again at 18 months with bleeding from the gastrointestinal tract but the diagnosis of factor VII deficiency was not made until the age of 3 years. He was treated with fresh frozen plasma and subsequently factor VII concentrates and to date remains well. To identify the causative mutation, the factor VII gene was screened by SSCP and direct sequence analysis. A single homozygous 2bp deletion (-CT) mutation was identified in exon 1a removing nucleotides 27/28 (codons 52/53). Both parents, who were first cousins, were heterozygous for the mutation. The mutation located in the prepropeptide of factor VII, results in a complete absence of factor VII in plasma. This case indicates that a complete absence of plasma factor VII is not necessarily a lethal condition.
Sensitization of CD4+ T Cells to Coagulation Factor VIII: Response in Congenital and Acquired Hemophilia Patients and in Healthy Subjects
Authors: Reding Mark , Wu Huiyun , Krampf Mark , Okita David , Diethelm-Okita Brenda , Christie Beverly , Key Nigel , Conti-Fine Bianca 
Published: March 2018

SummaryAntibodies (Ab) that inhibit factor VIII (fVIII) may develop in patients with hemophilia A and rarely in individuals without congenital fVIII deficiency (acquired hemophilia). Synthesis of fVIII inhibitors requires CD4+ T cells. We investigated the proliferative response of blood CD4+ cells from 11 patients with congenital or acquired hemophilia and 12 healthy subjects, to recombinant human fVIII, and to pools of overlapping synthetic peptides spanning the sequences of individual fVIII domains. All patients had CD4+ cells that responded to fVIII. The intensity of the responses fluctuated over time: several patients had brief periods when they did not respond to fVIII. All healthy subjects had transient CD4+ responses to fVIII, that were significantly lower than those of hemophilia patients. Also, healthy subjects responded to fVIII less frequently and for shorter periods than hemophilia patients. All patients and healthy subjects recognized several fVIII domains: the A3 domain was recognized most strongly and frequently. The transient sensitization of CD4+ cells to fVIII in healthy subjects suggests that inadequate tolerization of CD4+ cells to fVIII, due to lack of endogenous fVIII, is an important factor in the development of clinically significant anti-fVIII antibodies in hemophilia A.
The Occurrence of Subsequent Malignancy in Patients Presenting with Deep Vein Thrombosis: Results from a Historical Cohort Study
Authors: Rajan Raghu , Gent Michael , Hirsh Jack , Geerts William , Skingley Peter , Julian Jim , Levine Mark 
Published: March 2018

SummaryBackground: Several studies have reported that patients who present with idiopathic deep vein thrombosis (DVT) have an increased risk of subsequently developing cancer. A clinical trial had previously been conducted examining the optimal duration of oral anticoagulant therapy following initial heparin treatment in patients with proximal DVT.Methods: A historical cohort study was performed on patients enrolled in the duration of anticoagulant trial. Patients known to have cancer at the time of entry into the trial were excluded. The qualifying DVTs were classified as idiopathic (no known associated risk factors) or secondary without knowledge of subsequent recurrent venous thrombosis or cancer. The patients were then followed for the development of cancer.Results: Thirteen (8.6%) of the 152 patients in the idiopathic cohort subsequently developed cancer compared to eight (7.1%) of 112 patients in the secondary cohort, P = 0.86. Two (5.4%) of 37 patients with recurrent venous thromboembolism and 19 (8.4%) of 227 patients without recurrent thromboembolism developed cancer, P = 0.7.Conclusion: Our study did not detect an increased risk of subsequent cancer in patients presenting with idiopathic DVT compared to secondary DVT; nor did we detect an increased incidence of cancer in patients with recurrent venous thromboembolism. Further studies are required prior to pursuing a policy of aggressive screening for cancer in patients with idiopathic venous thromboembolism.
Dominant C2 Domain Epitope Specificity of Inhibitor Antibodies Elicited by a Heat Pasteurized Product, Factor VIII CPS-P, in Previously Treated Hemophilia A Patients without Inhibitors
Authors: Sawamoto Yoshikatsu , Prescott Richard , Zhong Degang , Saenko Evgueni , Mauser-Bunschoten Eveline , Peerlinck Kathelijne , van den Berg Marijke , Scandella Dorothea 
Published: March 2018

SummaryFrom June, 1990, to November, 1991, in The Netherlands and Belgium, 16 previously treated severe hemophilia A patients (PTP) developed inhibitors after exposure to factor VIII CPS-P, a new heat pasteurized product. A previously untreated patient (PUP) also developed an inhibitor to CPS-P. In inhibitor neutralization assays with recombinant fVIII C2 and A2 domain polypeptides, plasmas from 14 PTPs were ≥79% neutralized by C2 and <10% by A2, but the PUP plasma was partially neutralized by C2 (48%) and A2 (28%). Immunoprecipitation assays of the PTP and PUP plasmas with the fVIII heavy chain and with recombinant C2 and A3-C1 polypeptides confirmed that the C2 dominant immune response to CPS-P was found only in the PTPs. Competition of the binding of 2 inhibitors to 125I-CPS-P by unlabeled CPS-P and another plasma fVIII was similar, demonstrating that the antibody response was not directed to epitopes only present in CPS-P. We propose that the immunogenicity of the CPS-P C2 domain was altered by heat pasteurization.
Fibrillin Containing Elastic Microfibrils Support Platelet Adhesion under Dynamic Shear Conditions
Authors: McIntire Larry , Moake Joel , Kuo Huey-Ju , Qian Rui-Qing , Glanville Robert , Schwartz Elaine , Rand Jacob , Ross Julia 
Published: March 2018

SummaryThe vascular subendothelium contains macromolecular structures called microfibrils. Type VI collagen is one protein found in microfibrils that supports platelet adhesion and aggregation and we have previously evaluated the roles of platelet receptors and vWf involved in these processes under physiological shear conditions. Here we investigate the ability of fibrillin containing elastic microfibrils to support mural thrombus formation. Our results show that elastic microfibril surfaces support platelet adhesion under low shear conditions at a level similar to collagen VI tetramers. However, the degree of aggregation on the elastic microfibril surface is much higher. Both adhesion and aggregation were shown to be mediated by the GPIIb-IIIa platelet receptor. Elastic microfibrils do not support the formation of mural thrombi under high shear conditions. These results suggest roles for both collagen VI and fibrillin containing elastic microfibrils in modulating the platelet response to blood vessel injury.
Antagonism of vWF Inhibits both Injury Induced Arterial and Venous Thrombosis in the Hamster
Authors: Yamamoto Hiroshi , Vreys Ingrid , Stassen Jean Marie , Yoshimoto Ryota , Vermylen Jos , Hoylaerts Marc 
Published: March 2018

Summaryvon Willebrand factor (vWF) is instrumental in arterial but has also been implicated in venous thrombogenesis. To address its role in venous thrombosis, experimental thrombosis was induced in the carotid artery and the femoral vein of hamsters, following which thrombus prevention by two different antagonists of vWF was studied. The first antagonist was the anti-human vWF monoclonal antibody AJvW-2, which inhibits the botrocetin and ristocetin induced aggregation of human blood platelets. AJvW-2 reacts with an epitope present in the A1 domain of vWF in very different species (human, pig, rabbit, dog, Guinea pig and rat). This epitope was found to be conformational and overlapping with vWF binding sites for aurin tricarboxylic acid (ATA), but not for botrocetin and heparin. AJvW-2 has affinities for vWF in the absence (Kd = 0.5 ± 0.03 nmol/l in solution) and in the presence of shear stress (Kd = 3.3 ± 0.6 nmol/l during perfusion at 1,300 s–1 over subendothelial matrix associated vWF) sufficiently elevated to neutralize vWF. During perfusion of subendothelial matrix with anticoagulated human blood, the surface covered by adhering platelets was reduced by AJvW-2, with IC50s equal to 6.6 ± 0.34 μg/ml at 1,300 s–1 and to 1 ± 0.01 μg/ml at 2,700 s-1. As a second antagonist, molecular size gel filtered ATA was selected. Fractionated ATA inhibited platelet adhesion to matrix with IC50s equal to 0.27 ± 0.09 mmol/l at 1,300 s –1 and 0.16 ± 0.008 mmol/l at 2,700 s –1. When administered to hamsters, AJvW-2 prevented thrombosis in the injured carotid artery dose-dependently (ED50 = 0.15 ± 0.01 mg/kg). Thrombosis in the similarly injured femoral vein was however also inhibited (ED50 = 0.37 ± 0.06 mg/kg). Likewise, fractionated ATA completely inhibited carotid artery thrombosis (ED50 = 0.42 ± 0.13 mg/kg), but also interfered with femoral vein thrombosis (apparent ED50 between 2 and 3 mg/kg). We conclude that antagonizing the vWF A1 domain by AJvW-2 and to a lesser extent also by fractionated ATA, inhibits thrombosis not only in the arterial but also in the venous circulation. Since venous thrombi were prevented at only 3-5-fold higher doses of antagonist, vWF participates in injury induced venous thrombosis.
Inhibitory Effect of Piracetam on Platelet-rich Thrombus Formation in an Animal Model
Authors: Stockmans F. , Deberdt W. , Nyström Å. , Nyström E. , Stassen J. M. , Vermylen J. , Deckmyn H. 
Published: March 2018

SummaryIntravenous administration of piracetam to hamsters reduced the formation of a platelet-rich venous thrombus induced by a standardised crush injury, in a dose-dependent fashion with an IC50 of 68 ± 8 mg/kg. 200 mg/kg piracetam also significantly reduced in vivo thrombus formation in rats. However, in vitro aggregation of rat platelets was only inhibited with piracetam-concentrations at least 10-fold higher than plasma concentrations (6.2 ± 1.1 mM) obtained in the treated animals. No effects were seen on clotting tests.In vitro human platelet aggregation, induced by a variety of agonists, was inhibited by piracetam, with IC50’s of 25-60 mM. The broad inhibition spectrum could be explained by the capacity of piracetam to prevent fibrinogen binding to activated human platelets. Ex vivo aggregations and bleeding times were only minimally affected after administration of 400 mg/kg piracetam i.v. to healthy male volunteers, resulting in peak plasma levels of 5.8 ± 0.3 mM.A possible antiplatelet effect of piracetam could be due to the documented beneficial effect on red blood cell deformability leading to a putative reduction of ADP release by damaged erythrocytes. However similarly high concentrations were needed to prevent stirring-induced “spontaneous” platelet aggregation in human whole blood.It is concluded that the observed antithrombotic action of piracetam cannot satisfactorily be explained by an isolated direct effect on platelets. An additional influence of piracetam on the rheology of the circulating blood and/or on the vessel wall itself must therefore be taken into consideration.
Hereditary Homozygous Heparin Cofactor II Deficiency and the Risk of Developing Venous Thrombosis
Authors: Villa Piedad , Vaya Amparo , España Francisco , Ferrando Fernando , Mira Yolanda , Estellés Amparo , Aznar Justo 
Published: March 2018

SummaryHeparin cofactor II (HCII) is a specific inhibitor of thrombin in the presence of heparin or dermatan sulphate. Although there have been reports on families in which a heterozygous HCII deficiency is associated with thromboembolic events, several epidemiological studies revealed that heterozygous HCII deficiency is as prevalent among healthy subjects as it is among patients with deep venous thrombosis (DVT). It is therefore not yet clear whether HCII is or is not a thrombotic risk factor.We analyze and describe in an extended family the biochemical and genetic thrombophilic risk factors and evaluate the potential thrombotic risk involved in homozygous and heterozygous HCII deficiency, either alone or associated with other thrombotic or circumstantial risk factors. The propositus has had three episodes of DVT and a pulmonary embolism. During the first episode of DVT the patient was diagnosed as having AT deficiency. Later, a functional and antigenic HCII deficiency, compatible with the homozygous form, was detected. The family study shows that both the propositus and her sister have homozygous HCII deficiency and that 12 of the 27 family members have heterozygous HCII deficiency.This is possibly the first case report on a homozygous phenotype for the HCII deficiency with, in addition, partial AT deficiency. The propositus has suffered several thrombotic events, unlike the other 12 family members with heterozygous HCII deficiency and her sister, who is also homozygous for this disorder. We suggest that HCII deficiency may play a limited in vivo role as a thrombotic risk factor unless associated with AT deficiency or another congenital thrombotic risk factor.
Risk Factors Associated with Postpartum Ovarian Vein Thrombosis
Authors: Salomon Ophira , Apter Sara , Shaham Dorith , Hiller Nurith , Bar-Ziv Jacob , Itzchak Yacov , Gitel Sanford , Rosenberg Nurit , Strauss Simon , Kaufman Nathan , Seligsohn Uri 
Published: March 2018

SummaryThrombosis of the ovarian vein is a remarkable process occuring within a few days of labor in 1:500-1:2000 women. Its presentation is characterized by fever, abdominal pain and occasionally by a palpable abdominal mass that in earlier years sometimes lead to explorative laparotomy. With the advent of modern imaging techniques the diagnosis can be made relatively easily. The pathogenesis has been attributed to an infectious process expanding from the uterus to the right ovarian vein and stasis. A predisposition towards thrombosis has not been so far explored. In this study we retrospectively analysed the clinical features, diagnosis and treatment of 22 patients with objective documentation of post partum ovarian vein thrombosis (POVT) and assessed potential risk factors. In 11 of the 22 patients (50%) inherited prothrombotic risk factors were detected as follows: 4 were heterozygous for factor V G1691 A, 2 had protein S deficiency, one had protein S deficiency and was heterozygous for factor V G1691A, and 4 were homozygous for MTHFR C677T. Eight of the 11 patients who bore a prothrombotic predisposition underwent cesarean section. Taken together, the data suggest that POVT may result from the combined effect of an infection, cesarean section and a prothrombotic tendency.
Genetic Modulation of Plasma Protein S Levels by Two Frequent Dimorphisms in the PROS1 Gene
Authors: Duchemin J. , Levent M. , Gouault-Heilmann M. , Leroy-Matheron C. 
Published: March 2018

SummaryWe studied two polymorphisms located close to or within the 3’-untranslated (3’-UT) region of the PROS1 gene [an A to G transition at nt 2148 (Pro 626) and an A to C substitution at nt 2698] in 110 healthy volunteers. The allele frequency of the nt 2148 G variant was 35%, and that of the nt 2698 A variant was 27%. We found a relationship between the two dimorphisms (both separately and together) and the plasma total protein S antigen (tPS) level. The impact of the neutral Pro 626 dimorphism was more significant than that of nt 2698 C/A (p = 0.0003 and p = 0.013, respectively). The lowest tPS values were observed in subjects with the Pro 626;nt 2698 GG;CC genotype, and the highest values in those with the AA;AA genotype. Both polymorphisms acted independently of sex and age. The mechanisms by which the two polymorphisms regulate tPS synthesis were not revealed by the studies of platelet mRNA. This study provides the first evidence of a genetic modulation of tPS levels, which, in addition to age and sex, contributes to the wide normal range of tPS in plasma. Determination of these two polymorphisms could be a valuable additional tool for studying PS.
Familial Coagulation Factor V Deficiency Caused by a Novel 4 Base Pair Insertion in the Factor V Gene: Factor V Stanford
Authors: Hiraki D. D. , Jones C. D. , Gross N. , Grumet F. C. , Zehnder J. L. 
Published: March 2018

SummaryAn index patient with pseudohomozygosity for factor V Leiden was identified. Each of his two children inherited a different paternal factor V allele; a daughter was heterozygous for factor V Leiden, with 100% factor V activity, and a son was heterozygous for factor V deficiency, with 50% factor V activity. Genomic DNA was obtained from family members, and the 25 factor V exons and flanking intronic regions were sequenced in the proband and confirmed in the children. Within exon 13 of factor V, a 4 base insertion was found at NT 2856 in the proband and son, but not the daughter. This mutation, here designated factor V Stanford, results in a frameshift with loss of a thrombin activation site (R1545V) and premature termination of translation at amino acid 1560.
Adhesive Domains in the Collagen III Fragment α1(III)CB4 that Support α2β1- and von Willebrand Factor-mediated Platelet Adhesion under Flow Conditions
Authors: IJsseldijk Martin , Heijnen-Snyder Glenda , Huizinga Eric , Morton Laurence , Knight C. Graham , Sixma Jan , de Groot Philip , Barnes Michael , Verkleij Marilyn 
Published: March 2018

SummarySeven overlapping peptides derived from the bovine α1(III)CB4 fragment of collagen III support static platelet adhesion, and an integrin α2β1-recognition site has been assigned within this fragment to residues 522-528 of the collagen α1(III) chain; (25). In this study we found that two of the peptides, CB4(III)-6 and -7, were able to support platelet adhesion under flow conditions, whereas the other peptides showed either very little (CB4(III)-1 and -4) or no platelet adhesion at all (CB4(III)-2, -3 and -5). Using the recombinant leech anti-platelet protein (rLAPP), known to prevent both α2β1 integrin- and von Willebrand factor (vWF)-binding to collagen, we observed almost complete inhibition of platelet adhesion to peptides CB4(III)-6 and -7. In solidphase binding assays rLAPP bound to CB4(III)-6 and -7 and to CB4(III)-6/7, containing the peptide 6/7 overlap sequence, and not to any other peptide. Our results suggest that the overlap sequence GPP*-GPRGGAGPP*GPEGGK (single-letter amino acid code, P* = hydroxyproline), corresponding to residues 523-540 of the α1(III) collagen chain, contains a binding site for rLAPP. Monoclonal antibodies (MoAbs) directed against the α2 subunit of integrin α2β1 inhibited platelet adhesion to both CB4(III)-6 and -7 by about 50%, showing that the α2β1-recognition site in this locality in α1(III)CB4 detected under static conditions is of sufficient affinity to withstand shear forces. Solid-phase binding studies indicated that vWF binds to CB4(III)-7 and to a lesser extent to CB4(III)-4. Furthermore, rLAPP competed with vWF in binding to CB4(III)-7. Our results indicate that residues 541-558 of the α1(III)-chain may contain one of the critical vWF-binding sites involved in the initial phase of platelet adhesion to collagen III. MoAbs against vWF (A1 and A3 domain) and glycoprotein (GP)Ib confirmed that vWF is involved in adhesion to CB4(III)-7 and showed that vWF is also involved in adhesion to CB4(III)-6 despite the absence of direct binding of vWF to the peptide. The existence of α2β1-, vWF- and rLAPP-binding sites all in close proximity in α1(III)CB4 testifies to the importance of this locus in collagen III for its platelet reactivity.
Recombinant Factor VIIa Does not Induce Hypercoagulability In Vitro
Authors: Cvirn Gerhard , Muntean Wolfgang , Gallistl Siegfried 
Published: March 2018

SummaryRecombinant factor VIIa (rVIIa) has been reported to be clinically effective and safe in haemophilic patients with inhibitor antibodies. Compared to activated prothrombin complex concentrates the risk of thrombotic complications seems to be very low after rVIIa administration. Determination of free thrombin generation has been shown to identify hypercoagulability. Therefore, free thrombin and prothrombinase activity (Xa generation) were assessed after extrinsic activation of rVIIa supplemented factor VIII and factor IX deficient plasma. Free thrombin generation was also determined after supplementation of (activated) prothrombin complex concentrates. Addition of 150 U rVIIa/ml shortened the clotting times markedly in control, factor VIII, and factor IX deficient plasma. In contrast, free thrombin and Xa generation were not different in the absence or presence of 150 U rVIIa/ml. Addition of (activated) prothrombin complex concentrates resulted in a marked increase of free thrombin generation in all investigated plasmas. Although in vitro studies cannot reflect specific clinical circumstances our results support the notion that rVIIa does not induce a hypercoagulable state as sporadically observed after administration of (activated) prothrombin complex concentrates.
Modulation of Platelet-neutrophil Interaction with Pharmacological Inhibition of Fibrinogen Binding to Platelet GPIIb/IIIa Receptor
Authors: Xiao Zihui , Frojmovic Mony , Théroux Pierre 
Published: March 2018

SummaryThe study investigated how drug inhibition of the GPIIb/IIIa receptor influences the interactions between platelets and leukocytes. These interactions are believed to play an important role in the etiology of the acute coronary syndromes. Thirty patients with unstable angina or non-Q-wave myocardial infarction were studied before the administration of tirofiban or placebo and after 4 h and 72 h. Platelet-leukocyte aggregates were characterized in whole blood using three-colour flow cytometry. The leukocyte population was isolated by a nucleic acid probe (LDS 751) and platelet-neutrophil coaggregates identified as particles binding both anti-CD42a-FITC and anti-CD45-PE. Tirofiban decreased by 25% the density of platelets in circulating platelet-neutrophil coaggregates (p <0.01), and prevented the increase induced by platelet agonist stimulation (p <0.0001). The reduction correlated with inhibition of fibrinogen binding to platelet (p <0.0001) and with inhibition of platelet aggregation (p <0.0001). The percentage of neutrophils with bound platelets following platelet agonist stimulation was, however, increased following GPIIb/IIIa inhibition. Thus, inhibition of GPIIb/IIIa receptor promotes platelet-neutrophil adhesion, but markedly reduces the binding density of platelets in the coaggregates.