bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two Distinct Mutations Cause Severe Hemophilia B in Two Unrelated Canine Pedigrees
Authors: Gu Weikuan , Catalfamo James , Ray Jharna , Ray Kunal , Brooks Marjory 
Published: March 2018

SummaryThe molecular defects causing severe factor IX deficiency were identified in two distinct canine breed-variants. Both defects were associated with an absence of plasma factor IX coagulant activity and antigen. A large deletion mutation was found in 1 breed variant, spanning the entire 5’ region of the factor IX gene extending to exon 6. An approximately 5 kb insertion disrupted exon 8 of the second breed-variant. This insertion was associated with alternative splicing between a donor site 5’ and acceptor site 3’ to the normal exon 8 splice junction, with introduction of a new stop codon. The resultant transcript lacked most of the factor IX catalytic domain and 3’ untranslated region. Molecular analyses of canine hemophilia B define an experimental model for study of inhibitor formation and gene therapy strategies, and provide insight into spontaneous mutation mechanisms in the factor IX gene and on the X chromosome of mammalian species.
Laboratory Testing for von Willebrand’s Disease: An Assessment of Current Diagnostic Practice and Efficacy by Means of a Multi-laboratory Survey
Authors: Smith Julian , Petinos Penny , Hertzberg Mark , Koutts Jerry ,   the RCPA Quality Assurance Program (QAP) in Haematology Haemostasis Scientific Advisory Panel, Favaloro Emmanuel 
Published: March 2018

SummaryWe report an evaluation of current laboratory practice for the diagnosis of von Willebrand’s disease (VWD) by means of a multilaboratory survey. This assessment was undertaken with the RCPA Quality Assurance Program (QAP) in Haematology, which covers a wide geographic area encompassing Australia, New Zealand and Asia. A total of 25 laboratories actively involved in testing for VWD were selected to participate in a sample testing assessment exercise. Samples comprised 10 plasmas: (i) a normal plasma pool (in duplicate), (ii) this pool diluted to 50% (in duplicate), (iii) a normal individual (×1), (iv) severe Type 1 VWD (×1), (v) Type 2B VWD (×2 unrelated donors), (vi) Type 3 VWD (×1), (vii) Type 2A VWD (×1). Laboratories were asked to perform all tests available to them in order to establish a laboratory diagnosis of VWD, and then to comment on the possibility or otherwise of VWD. Overall findings indicated a wide variation in test practice, in the effectiveness of various test procedures in detecting VWD, and in the ability of various composite test panels to identify type 2 VWD subtypes. Firstly, while all laboratories (n = 25) performed tests for FVIII:C activity, von Willebrand factor ‘antigen’ (VWF:Ag) and a functional VWF assay [using the ristocetin cofactor assay (VWF:RCo; n = 23) and/or the collagen binding assay (VWF:CBA; n = 12)], only three laboratories carried out VWF:Multimer analysis. Secondly, for the three quantitative VWF assays, 10/25 (40%) laboratories performed all three, whereas 15/25 (60%) performed only two [VWF:Ag and VWF:RCo (n = 13); VWF:Ag and VWF:CBA (n = 2)]. Thirdly, a variety of assay methodologies were evident for VWF:Ag [ELISA, electro-immuno diffusion (EID), latex immuno-assay (LIA), and VIDAS assay] and VWF:RCo (platelet agglutination/‘aggregometry’ and a ‘functional VWF:RCo-alternative’ ELISA assay). Between method analysis for the quantitative VWF assays showed that the VWF:RCo yielded the greatest degree of inter-laboratory assay variation, and had the poorest overall performance with respect to sensitivity to low levels of VWF. The VWF:CBA also performed better than the VWF:RCo in terms of ability to detect functional VWF ‘discordance’ (i.e. Type 2 VWD). Within VWF:Ag method analysis showed that the EID assay procedure was associated with the greatest variation in assay
The Risk of Early Recurrent Venous Thromboembolism after Oral Anticoagulant Therapy in Patients with the G20210A Transition in the Prothrombin Gene
Authors: Minar Erich , Hirschl Mirko , Bialonczyk Christine , Stain Milena , Mannhalter Christine , Stümpflen Andreas , Schneider Barbara , Lechner Klaus , Kyrle Paul , Eichinger Sabine 
Published: March 2018

SummaryA G20210A transition in the prothrombin gene is a common risk factor of venous thrombosis. The risk of recurrent venous thrombo-embolism in carriers of the 20210A allele is unknown and guidelines for secondary thromboprophylaxis in these patients are not available.In a prospective multicenter trial, 492 patients with a history of objectively documented venous thromboembolism were followed for a mean observation time of 24 ± 16 months after discontinuation of oral anticoagulants. Forty-two patients (8.5%) were carriers of the 20210A allele. Three of the 42 patients with the G20210A mutation (7%) and 54 of 450 patients without the mutation (12%) experienced recurrent venous thrombosis. At 24 months, the probability of recurrence was 8% (95% CI 0-16.7) in patients with the mutation and was 12.2% (95% CI 8.8-15.6) in patients without the mutation.In conclusion, the risk of early recurrent venous thromboembolism is not higher in patients with the G20210A mutation than in those without the mutation. Therefore, long-term secondary thromboprophylaxis with oral anticoagulants in heterozygous carriers of the 20210A allele is not justified.
Performance of a New Fibrin Monomer Assay to Exclude Deep Vein Thrombosis in Symptomatic Outpatients
Authors: Caliezi Christoph , Fünfsinn Nadja , Mauron Thomas , Baumgartner Iris , Sulzer Irmela , Ulrich Martin , Cottier Christoph , Biasiutti Franziska , Lämmle Bernhard , Wuillemin Walter 
Published: March 2018

SummaryIn this study we prospectively assessed the reliability of a new fibrin monomer assay in 106 outpatients with clinically suspected deep venous thrombosis of the lower limb. According to the results of the objective tests and using different cut-off points we calculated the sensitivity, specificity and negative predictive value of the fibrin monomer assay. The prevalence of deep vein thrombosis was 44.3% (31.1% proximal, 13.2% distal). Using a cut-off level of plasma fibrin monomer of 3.5 μg/ml, a sensitivity, specificity and negative predictive value of 100% (95% CI: 94-100%), 35.6% (95% CI: 23-48%) and 100% (95% CI: 86-100%), respectively, were obtained. The exclusion rate was 19.8% (95% CI: 12-27%) of all referred patients. These accuracy indices compared favourably with the respective results of a routine D-dimer ELISA used for comparison. Conclusion: This new fibrin monomer assay appears to be a reliable method for the exclusion of deep vein thrombosis in symptomatic outpatients.
A New Enzyme Immunoassay for Soluble Fibrin in Plasma, with a High Discriminating Power for Thrombotic Disorders
Authors: Laterveer-Vreeswijk G. H. , Lockwood D. , Szewczyk K. , Nieuwenhuizen W. , Bos R. 
Published: March 2018

SummaryFibrin formation is a multistep process initiated by thrombin. At first thrombin converts fibrinogen to fibrin molecules which in vivo form soluble complexes with fibrinogen. Soluble fibrin is considered to be an early biochemical marker for intravascular fibrin formation and impending thrombotic events, such as deep venous thrombosis (DVT), pulmonary embolism (PE) and disseminated intravascular coagulopathy (DIC).A new enzyme immunoassay (EIA) was developed on the basis of a monoclonal antibody directed against a fibrin specific neo-epitope located on the gamma-chain of fibrinogen; γ-(312-324). In addition, it was possible to prepare a lyophilized reference material of thrombin-generated soluble fibrin, that allowed for full antigen recovery after reconstitution with buffer. Assay conditions, e.g. solid phase-Ig concentration and buffer composition, sample and conjugate dilution, and incubation times were optimised.The present assay was found to be specific (no interference of homologous antigens) and reproducible (intra-assay CV 4-8%, inter-assay CV 4-9%), and therefore highly suited for measuring soluble fibrin levels in a plasma milieu. The median normal value for soluble fibrin was determined in plasma samples obtained from apparently healthy volunteers (n = 81) and found to be 0.040 μg/ml, with a range (10-90 percentiles) of 0.026-0.059 μg/ml.A retrospective study showed that soluble fibrin levels were highly significantly increased in patients with a confirmed diagnosis of DIC (median 1.042 μg FEU/ml, range 0.160-2.319 μg/ml, n = 21, P <0.0001 vs normal), PE (median 0.527 μg FEU/ml, range 0.084-1.234 μg/ml, n = 29, P <0.0001 vs normal) and DVT (median 0.126 μg FEU/ml, range 0.059-0.878 μg/ml, n = 36, P <0.0001 vs normal), as determined by the Mann-Whitney U-Test.
Influence of Three Types of Automated Coagulometers on the International Sensitivity Index (ISI) of Rabbit, Human, and Recombinant Human Tissue Factor Preparations
Authors: Houbouyan L. L. , Aillaud M. F. , Denson K. W. E. , Johnston M. , Kitchen S. , Lindahl T. L. , Marren M. , Martinuzzo M. E. , Droullé C. , Tripodi A. , Vergnes C. , Besselaar A. M. H. P. 
Published: March 2018

SummaryFive tissue factor reagents and three types of automated instruments for prothrombin time (PT) determination were studied in an international multicenter collaborative exercise. The purpose of this work was to determine the international sensitivity index (ISI) for each combination of reagent and instrument against the international reference preparation RBT/90. Each type of instrument was used by 3 or 4 centers to assess the interlaboratory variation of the ISI. The interlaboratory variation of the ISI for each combination of reagent and instrument ranged between 0.4% and 7.8% coefficient of variation. For three reagents, the mean ISI values for ACL (nephelometric) and STA (mechanical) were practically identical, but the mean ISI values for MLA (photo-optical) were at least 10% higher. For two other reagents prepared from rabbit tissue, the mean ISI values increased in the order ACL, STA, MLA. The widest range of mean ISI values was noted with one rabbit tissue factor reagent: 1.68 for ACL and 2.00 for MLA. Exclusion of patient specimens with INR <1.5 and INR >4.5 determined by the international reference preparation resulted in a slight decrease of the mean ISI.The interlaboratory variation of the International Normalized Ratio (INR) was assessed from the results obtained with common lyophilized and deep-frozen plasmas. The use of instrument-specific ISI values resulted in reduced interlaboratory variation of the INR. It is recommended that thromboplastin manufacturers provide instrument-specific ISI values.
β2-Glycoprotein I Is Proteolytically Cleaved In Vivo upon Activation of Fibrinolysis
Authors: Oort Erica , Lisman Ton , Meijers Joost , Derksen Ronald , de Groot Philip , Horbach Daniëlle 
Published: March 2018

Summaryβ2-glycoprotein I (β2GPI) is a plasma glycoprotein with unknown physiological function(s). In in vitro experiments it has been demonstrated that β2GPI has both anticoagulant properties, such as the inhibition of factor X and prothrombin activation and procoagulant properties, such as the inhibition of the anticoagulant activity of activated protein C. Besides this, β2GPI bound to cardiolipin is recognized by anti-phospholipid antibodies (aPL).In this study we demonstrate that β2GPI is very sensitive for cleavage between Lys317 and Thr318 by plasmin, resulting in two immunologically different cleaved forms. In vitro experiments show that these plasmin cleaved forms of β2GPI bind to negatively charged phospho-lipids with much lower affinity compared to intact β2GPI. Similar to plasmin, trypsin and elastase can also induce this proteolytical cleavage in β2GPI, whereas thrombin and factor Xa do not cleave β2GPI. The in vivo occurrence of the proteolytical cleavage was demonstrated by the finding that in plasmas of patients with disseminated intravascular coagulation(DIC) and in plasmas of patients treated with streptokinase, significant amounts of cleaved β2GPI (up to 12 μg/ml) are present.During the development of DIC, the increase in levels of cleaved β2GPI is accompanied by a 70% decrease in the levels of intact β2GPI, whereas in streptokinase treated patients levels of intact β2GPI stay within the normal range.This study demonstrates for the first time that during in vivo activation of fibrinolysis β2GPI is cleaved, which results in the formation of a form of β2GPI with much lower affinity for negatively charged phospholipids. Plasmin is most likely responsible for this modification.
Platelet Adhesion to Collagen Type I, Collagen Type IV, von Willebrand Factor, Fibronectin, Laminin and Fibrinogen: Rapid Kinetics under Shear
Authors: Simon Carl , Gear Adrian , Polanowska-Grabowska Renata 
Published: March 2018

SummaryExtracellular matrix proteins in the blood vessel wall fulfill an essential role in haemostasis by promoting platelet adhesion at the site of vessel injury. We have combined a continuous-flow system with affinity chromatography to study platelet adhesion under conditions mimicking arterial flow and have examined the adhesion kinetics of unstimulated platelets to collagens type I and IV, von Willebrand factor (vWf), fibronectin, laminin and to fibrinogen. In the absence of red cells, in ACD-prepared plasma adhesion to collagens type I and IV or vWf was rapid, efficient (>50% in <1 s ) and independent of shear rates from 650 to 3400 s-1with kinetics following an inverse exponential decay curve. We introduced a simple mathematical model in which this type of kinetics arises, and which may be more generally applicable to various adhesion processes under flow conditions. The model is characterized by the rate of platelet deposition on the adhesive surface being proportional to the number of platelets in the flow. Adhesion to fibronectin was independent of shear rate, but revealed a lag phase of ~1.5 s before significant adhesion began. Laminin and fibrinogen supported efficient adhesion at low shear rates (650-1000 s-1), but a lag phase of ~1.5 s was seen at high shear rates (1700-3400 s-1). Control proteins (albumin and gelatin) supported minimal adhesion. Nonspecific adhesion to poly-l-lysine differed from that to other substrate proteins in that the kinetics were linear. In conclusion, human platelets adhered specifically, rapidly (within seconds) and efficiently to several proteins under flow conditions and the kinetics of adhesion depended on the protein serving as substrate as well as on shear rate.
Human Atheromatous Plaque Extracts Induce Tissue Factor Activity (TFa) in Monocytes and also Express Constitutive TFa
Authors: Teodorescu Victoria , Rand Jacob , Rosman Alan , Niemetz Julian , Muhlfelder Thomas 
Published: March 2018

SummaryTissue factor activity (TFa) is a major activator of the coagulation cascade and may play a role in atheroma-induced thrombosis. Mono-cyte-macrophages (MO-MF) generate considerable quantities of TFa when stimulated by a variety of inducers. To test the hypothesis that MO could be induced by atheromatous plaque to generate TFa, plaque extracts obtained from patients with obstructive atheromatous disease were used. These extracts were also assayed for constitutive TFa. The constitutive activity was variable from extract to extract but could be very high, up to 250 U TFa. The TFa induced in MO could be also very high, up to 200 U (i.e. 1/5 of the TFa of full strength rabbit brain thromboplastin). These findings point to a major role for MO-MF TFa in the induction or thrombosis by atheromatous plaque.
Local versus Central Assessment of Venographies in a Multicenter Trial on the Prevention of Deep Vein Thrombosis in Neurosurgery
Authors: Rossi Romina , Taborelli Piera , Fioroni Claudio , Zerbi Daniela , Pattacini Pietro , Giugni Enrico , Bagatella Paola , Vaccarino Antonella , Agnelli Giancarlo 
Published: March 2018

SummaryVenography is the diagnostic method of choice for end-point measurement in multicenter trials on the prevention of postoperative deep vein thrombosis (DVT). The aim of the study was to determine the inter-observer agreement between the local and central assessment of venographies in a multicenter trial comparing enoxaparin and placebo in the prevention of DVT after elective neurosurgery.The study was run in seven centers experienced in venography trials on DVT prevention. The central and local adjudication panels were both blind with respect to the assigned treatment. The central panel was unaware of the local adjudication. Venographies were adjudicated as positive, negative or inadequate for adjudication and positive venographies as proximal or distal DVT. Inter-observer agreement was assessed according to the Cohen’s inter-observer variability index (K index).All 266 venographies (8 monolateral) were considered adequate for adjudication by both the central and local panels. A disagreement was found in 25 cases; K index = 0.75. Fourteen venographies adjudicated as negative centrally were considered positive locally (3 were proximal DVT). Eleven venographies adjudicated as positive centrally (1 was a proximal DVT) were considered negative locally. Enoxaparin was found to be more effective than placebo according to both the central and local adjudication: 16.9% versus 32.6% (Relative risk, RR = 0.52; CI95% 0.33-0.82) according to central adjudication; 18.5% versus 33.3% (RR = 0.56; CI95% 0.36-0.87) according to local adjudication.We conclude that a good inter-observer agreement in the assessment of venography was observed between the central and local adjudication in a study on DVT prevention run in a restricted experienced study framework. The cost and work overloading of central assessment of venographies in this study framework seems not to be justified.
Contribution of the -455G/A Polymorphism at the β-fibrinogen Gene to Erythrocyte Aggregation in Patients with Coronary Artery Disease
Authors: Weng Xiaoduan , Genest Jacques , Cloutier Guy 
Published: March 2018

Summary
Background. A high level of red blood cell (RBC) aggregation has been consistently found in patients with coronary artery disease (CAD) in case-control studies. Plasma fibrinogen has been shown to promote RBC aggregability. The purpose of this study was to investigate the influence of the genetic variability of the β-fibrinogen gene on RBC aggregation in patients with CAD. Methods and Results. The genotype of the β-fibrinogen gene locus was determined by polymerase chain reaction using the restriction enzyme HaeIII for a G to A substitution at position -455 upstream from the transcriptional start site in 135 French Canadians with premature CAD (age: 51 ± 7 years). Indices measuring the RBC aggregation kinetics (S10) and shear resistance of the aggregates (γS) were obtained by laser reflectometry. Patients were separated into groups by using the medians of S10 and γS. Using χ2 analyses, the distribution of the -455GG, -455GA, and -455AA genotypes in the groups with high levels of S10 (0.43, 0.49, and 0.08) and γS (0.45, 0.49, and 0.06) were found to be significantly distinct from those in the groups with low levels of S10 (0.67, 0.27, and 0.06; p <0.05) and γS (0.70, 0.23, and 0.07; p <0.01). High levels of RBC aggregation were closely associated with the rare -455A allele. Multivariate linear regression analyses showed that S10 was positively correlated with the linear combination of the fibrinogen concentration, age, and the -455G/A genotype (adjusted r = 0.63, p <0.0001). Fibrinogen and age were positive determinants, and HDL-cholesterol was a negative predictor of γS (adjusted r = 0.51, p <0.0001). Conclusion. These findings support the hypothesis that RBC hyperaggregation in premature CAD may be associated with the β-fibrinogen -455G/A polymorphism. This association may be explained by a change in the concentration and/or the functional properties of the fibrinogen protein.
Factor IX Gene Analysis In 70 Unrelated Patients with Haemophilia B: Description of 13 New Mutations
Authors: Trzeciak M. C. , Durin A. , Pernod G. , Gay V. , Ménart C. , Sobas F. , Dechavanne M. , Attali O. , Vinciguerra C. , Négrier C. 
Published: March 2018

SummarySeventy unrelated patients suffering from haemophilia B have been screened for determining the molecular defect and for evaluating the spectrum of factor IX mutations in the Rhône Alpes region in France. Most patients were characterized with respect to factor IX antigen and factor IX coagulant activity. We have used denaturing gradient gel electrophoresis to obtain a full scanning of the whole coding, promoter, and exon flanking sequences of the factor IX gene. This technique enabled us to determine the molecular defect in 68 out of 70 families (97%), and the mutation was further identified in the two last patients with a direct sequencing of the gene. A total of 2 complete gene deletions in patients with antifactor IX inhibitor, 6 small insertions/ deletions and 62 point mutations were found. Two of these nucleotide substitutions (Arg145His and Ala233Thr) were detected in 21 patients (30%) suggesting the existence of a local founder effect. Thirteen mutations were previously undescribed, including 7 missense mutations. The detection of mutations in patients affected with haemophilia B may shed some light in the structure-function relationship of factor IX molecule within the coagulation system.
Variations in Coagulation Factors in Women: Effects of Age, Ethnicity, Menstrual Cycle and Combined Oral Contraceptive
Authors: Kadir Rezan , Sabin Caroline , Owens Dale , Lee Christine , Economides Demetrios 
Published: March 2018

SummaryTo assess variations of coagulation factors in women, 123 women were included in a cross-sectional study of the effect of age, ethnic origin, blood group and menstrual cycle on surface induced coagulation time (activated partial thromboplastin time) and plasma levels of Factor VIII clotting assay, von Willebrand factor antigen, von Willebrand factor activity and factor XI. The effect of menstrual cycle was further assessed in a longitudinal study including 39 Caucasian women, 20 of whom were using combined oral contraceptives. Activated partial thromboplastin time was longer in women with blood groups B or O, and plasma levels of factor VIII clotting assay, von Willebrand factor antigen and von Willebrand factor activity were significantly higher in black women. Fibrinogen, von Willebrand factor antigen and von Willebrand factor activity concentrations showed strong cyclic variations with peak values in the luteal phase. This pattern was dampened for von Willebrand factor antigen and von Willebrand factor activity but completely disappeared for fibrinogen with the use of combined oral contraceptives. There was a cyclical pattern for factor VIII clotting assay in pill users, evidence of which was not evident in non-pill users. There were strong associations between the levels of von Willebrand factor antigen and von Willebrand factor activity and age, with levels rising by an average of 0.17 and 0.15 U/ml, respectively, for each 10 year increase in age. In conclusion, there are great inter- and intraindividual variations in coagulation markers in women due to different physiological conditions such as age, ethnicity, blood group and phases of the menstrual cycle. However, there were no significant associations between coagulation markers and weight, alcohol consumption or smoking status.