bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple electrode aggregometry: A new device to measure platelet aggregation in whole blood
Authors: Calatzis Andreas , Penz Sandra , Losonczy Hajna , Siess Wolfgang , Tóth Orsolya 
Published: December 2006

SummarySeveral methods are used to analyse platelet function in whole blood. A new device to measure whole blood platelet aggregation has been developed, called multiple electrode platelet aggregometry (MEA). Our aim was to evaluate MEA in comparison with the single platelet counting (SPC) method for the measurement of platelet aggregation and platelet inhibition by aspirin or apyrase in diluted whole blood. Platelet aggregation induced by different concentrations of ADP, collagen and TRAP-6 and platelet inhibition by apyrase or aspirin were determined in citrateor hirudin-anticoagulated blood by MEA and SPC. MEA indicated that spontaneous platelet aggregation was lower, and stimulated platelet aggregation was higher in hirudin- than citrate-anticoagulated blood. In hirudin-anticoagulated, but not citrate-anticoagulated blood, spontaneous platelet aggregation measured by MEA was inhibited by apyrase. For MEA compared with SPC the dose response-curves of agonist-induced platelet aggregation in citrate- and hirudin-blood showed similar EC50 values for TRAP, and higher EC50 values for ADP (non-significant) and collagen (p<0.05). MEA and the SPC method gave similar results concerning platelet-inhibition by apyrase and aspirin. MEA was more sensitive than SPC to the inhibitory effect of aspirin in collagen-induced aggregation. In conclusion, MEA is an easy, reproducible and sensitive method for measuring spontaneous and stimulated platelet aggregation, and evaluating antiplatelet drugs in diluted whole blood. The use of hirudin as an anticoagulant is preferable to the use of citrate. MEA is a promising technique for experimental and clinical applications.
Review: Laboratory markers quantifying prothrombin activation and actions of thrombin in venous and arterial thrombosis do not accurately assess disease severity or the effectiveness of treatment
Authors: Ofosu Frederick 
Published: December 2006

SummaryThrombin is normally produced for hemostasis and physiological wound healing. Increased thrombin production in vivo, cell activation and inflammation mediated in part by thrombin are hallmarks of both arterial and venous thrombosis. Thrombin generates (pro) coagulant, mitogenic, inflammatory and anticoagulant responses by interacting witha variety of cells in vivo.Both direct and indirect thrombin inhibitors are effective drugs for preventing and treating the consequences of arterial and venous thrombosis. For these reasons, measurements of the production and activities of thrombin in vivo have the potential for gauging the extent of thromboembolism and the responses of patients to anticoagulant, antiplatelet and anti-inflammatory drugs. How-ever, a critical review of published information suggests that measurement of thrombin production and activity in patients at risk for and in patients with significant thrombosis generally does not provide information useful for clinical decision-making. This lack of clinical utility of levels of thrombin production in vivo may arise from two causes: the inability of the measurement to differentiate between physiological (hemostatic) and disease-related (pathological) sources and/or causes of thrombin production in vivo, and the inability of antithrombotic treatment modalities to permanently eliminate the stimuli that cause increased thrombin production evident in venous and arterial thrombosis.
A versatile strategy for preimplantation genetic diagnosis of haemophilia A based on F8-gene sequencing
Authors: Sánchez-García Jorge , Gallardo Dominique , Navarro Joaquima , Márquez Carmen , Gris Josep , Sánchez Maria , Altisent Carme , Vidal Francisco 
Published: December 2006

SummaryPreimplantation genetic diagnosis (PGD) of hemophilia A (HA) and other X-linked diseases through sex selection implies that male embryos will be systematically discarded, even though 50% are unaffected. The objective of the present work was to develop a PGD protocol for direct mutation identification that could be applied to first polar bodies (1PBs) in several HA clinical cases. Single buccal cells from controls and patients, and 1PBs were subjected to primer extension preamplification (PEP) PCR followed by amplification of F8 gene coding and intronic flanking regions, and direct sequencing. Moreover, multiplex fluorescent amplification of four short tandem repeats was adapted to a single cell preamplification in order to rule out contamination and allele drop-out, and for confirmatory indirect diagnosis. A couple at risk of HA transmission, with a familial mutation characterized as a 41-bp duplication in exon 14 of the F8 gene, was selected for the first clinical study. After optimizing the protocol, the complete F8 gene coding sequence was obtained from single cells to demonstrate the sensitivity of our methodology although in any clinical case only the relevant region, not the whole gene, must be amplified. The woman enrolled in the first clinical case has completed the first in-vitro fertilization cycle, and seven oocytes were analyzed with concordant results by both linkage analysis and direct sequencing method. Only one oocyte, among those diagnosed as mutation free, developed to embryo at day 3. It was transferred but pregnancy was not achieved. This PGD procedure enables non-affected and noncarrier embryo selection in families with any point or smallrange mutation in the F8 gene, without the need for further custom-made modifications.
Rational humanization of the powerful antithrombotic anti-GPIbα antibody: 6B4
Authors: Fontayne Alexandre , Vanhoorelbeke Karen , Pareyn Inge , Van Rompaey Isabel , Meiring Muriel , Lamprecht Seb , Roodt Jan , Desmet Johan , Deckmyn Hans 
Published: December 2006

SummaryFab-fragments of the monoclonal antibody 6B4, raised against human glycoprotein Ibα (GPIbα), have a powerful antithrombotic effect in baboons by blocking the GPIbα binding site for von Willebrand factor (VWF), without significant prolongation of the skin bleeding time. In order to bring this antibody to the clinic,we here humanized for the first time an anti-human GPIbα by variable-domain resurfacing guided by computer modeling. First, the genes coding for the variable regions of the heavy and light chains of 6B4 were cloned and sequenced. Based on this,a three-dimensional structure of the Fv-fragment was constructed by using homology-based modeling, and with this and comparison with antibodies with known structure,”murine” putative immunogenic residues which are exposed, were changed for “human-like” residues. The humanized Fab-fragment, h6B4-Fab, was constructed in the pKaneo vector system, expressed and purified and showed in vitro an unaltered, even slightly higher binding affinity for its antigen than the murine form as determined by different ELISA set-ups and surface plasmon resonance. Finally, injection of doses of 0.1 to 1.5 mg/kg of h6B4-Fab in baboons showed that both pharmacokinetics and ex-vivo bio-activity of the molecule were to a large extent preserved.In conclusion, the method used here to humanize 6B4 by resurfacing resulted in a fully active derivative, which is now ready for further development.
Fucosylated chondroitin sulfate as a new oral antithrombotic agent
Authors: Fonseca Roberto , Mourão Paulo 
Published: December 2006

SummaryFucosylated chondroitin sulfate is a potent anticoagulant polysaccharide extracted from sea cucumber. Its anticoagulant activity is attributed to the presence of sulfated fucose branches. We have shown that intravascular injection of fucosylated chondroitin sulfate inhibits thrombus formation in a venous and an arterial shunt model in rats. Since this compound resists digestion by enzymes that cleave mammalian glycosaminoglycans, we investigated the possibility that fucosylated chondroitin sulfate might be absorbed after oral administration. In fact, after oral administration of fucosylated chondroitin sulfate to rats, we observed a dose-dependent increase in the plasma anticoagulant activity, as assessed by assays for activated partial thromboplastin time (aPTT) and thrombin time (TT) (about 3-and 5-fold, respectively) and by anti-IIa activity. Furthermore, animals receiving daily oral doses of this glycosaminoglycan showeda decrease in thrombus weight on experimental models of venous and arterial shunt thrombosis. This antithrombotic action clearly has a strong relationship with anticoagulant activity. Similar doses of heparin administered orally had no effect on the plasma anticoagulant activity or on the thrombus weight. Finally, we observed that fucosylated chondroitin sulfate given orally to rats did not modify the bleeding time. Overall, our results indicate that fucosylated chondroitin sulfate is absorbed after oral administration and could become a promising oral anticoagulant.
Plasminogen activator inhibitor-1 impairs plasminogen activationmediated vascular smooth muscle cell apoptosis
Authors: Rossignol Patrick , Anglès-Cano Eduardo , Lijnen Henri 
Published: December 2006

SummaryThe role of plasminogen activator inhibitor-1 (PAI-1) in vascular smooth muscle cell (VSMC) apoptosis mediated by plasminogen activation was studied with the use of aorticVSMC derived from mice with deficiency of PAI-1 (PAI-1-/-), tissue-type (t-PA-/-) or urokinase-type (u-PA-/-) plasminogen activator or from wildtype (WT) mice with corresponding genetic background. Plasminogen incubated with confluentVSMC was activated ina concentration-dependent and saturable manner for all four cell types, with maximal activation rates that were comparable for WT,u-PA-/and t-PA-/cells,but about two-fold higher for PAI-1-/cells. Plasminogen activation was impaired by addition of the lysine analogue 6-aminohexanoic acid, and by addition of t-PA and u-PA neutralizing antibodies, suggesting that it depends on binding to cell surface COOH-terminal lysine residues, and on plasminogen activator activity. Morphological alterations consistent with apoptosis were observed much earlier in PAI-1-/than in WT VSMC. Without addition of plasminogen, the apoptotic index was similar for all four cell types, whereas after incubation with physiological plasminogen concentrations, it was greater in PAI-1-/VSMC, as compared to WT, t-PA-/or u-PA-/VSMC. Furthermore, the apoptotic rate paralleled the release of plasmin. Thus, plasmin-mediated apoptosis of VSMC occurs via plasminogen activation by either t-PA or u-PA and is impaired by PAI-1.
Incidence of venous thromboembolism in first-degree relatives of patients with venous thromboembolism who have factor V Leiden
Authors: Kearon Clive , Leroyer Christophe , Mercier Bernard , Abgrall Jean , Le Gal Grégoire , Lacut Karine , Oger Emmanuel , Bressollette Luc , Ferec Claude , Lamure Michel , Mottier Dominique , Couturaud Francis ,   for the Groupe d’Etude de la Thrombose de Bretagne Occidentale (G.E.T.B.O)
Published: December 2006

SummaryThe factor V Leiden (FVL) mutation, a genetic abnormality with an autosomal mode of inheritance, is associated with an increased risk of venous thromboembolism (VTE). We aimed to determine the annual incidence of VTE in first-degree relatives of patients with VTE and FVL and to identify factors in patients and the relatives that influence this incidence. In this retrospective and prospective cohort study, the incidence of objectively diagnosed first episodes of VTE was assessed in 553 first-degree relatives of 161 patients with acute VTE and FVL. The annual incidence of VTE was 0.43% (95% CI, 0.3 to 0.56) with FVL and 0.17 % (95% CI, 0.07 to 0.27) without FVL (relative risk of 2.5, 95% CI, 1.3 to 4.7). A majority (70%) of episodes of VTE were provoked, and this proportion was similar with and without FVL. A larger proportion of VTE was provoked in women (83%) that in men (33%), with the difference accounted for by pregnancy and use of oral contraceptives. The proportion of pregnancies complicated by VTE was 3.9% (95% CI, 2.0–5.8) with FVL and 1.4% (95% CI, 0.04–2.7) without FVL. FVL is associated with a two-to threefold increase in VTE in first-degree relatives of patients with VTE. No subgroup of relatives was identified who require more than routine prophylaxis because of a particularly high risk of VTE.
An investigation of the von Willebrand factor genotype in UK patients diagnosed to have type 1 von Willebrand disease
Authors: Grundy Pamela , Keeney Stephen , Lester William , Enayat Said , Guilliatt Andrea , Bowen Derrick , Pasi John , Keeling David , Hill Frank , Bolton-Maggs Paula , Hay Charles , Collins Peter , Cumming Anthony ,   on behalf of the UK Haemophilia Centre Doctors’ Organisation
Published: December 2006

SummaryForty families diagnosed by UK centres to have type 1 VWD were recruited. Following review, six families were re-diagnosed to have type 2 VWD, one to have a platelet storage pool disorder, and one family was determined to be unaffected. Direct DNA sequencing of the promoter region and all exons and intronic boundaries of the VWF gene identified six mutations likely to be causative of VWD in index cases of nine of the 32 (28%) confirmed type 1 VWD families. These included R1205H (3614G>A) VWD Vicenza, P1648fsX45 (4944delT), D141G (422A>G) and three splice site mutations: 3108+5G>A, 7437+1G>A and 3379+1G>A. The Y1584C (4751A>G) polymorphism was present in eight additional families. No significant VWF gene mutation or polymorphism was identified in 15 of the32 type 1VWD index cases (47%). Haplotype studies were performed using a panel of VWF polymorphisms to investigate the segregation in families of VWD phenotype with the VWF gene. In 13 of the 32 families it was likely that VWD segregated with the VWF gene. In eight families (25%) VWD clearly did not segregate with the VWF gene. We suggest that mutation screening of the VWF gene has limited general utility in genetic diagnostic and family studies in type 1 VWD. If genetic studies are performed, the incomplete penetrance and variable expressivity of type 1 VWD must be taken into account. Unless linkage of VWD phenotype with the VWF gene can be clearly demonstrated, the results of any genetic family studies should be interpreted with caution.
The effect of glycaemic control on fibrin network structure of type 2 diabetic subjects
Authors: Covic Namukolo , Loots Du Toit , van der Westhuizen Francois , van Zyl Danie , Rheeder Paul , Jerling Johann , Weisel John , Pieters Marlien 
Published: December 2006

SummaryDiabetic subjects have been shown to have altered fibrin network structures. One possible cause may be fibrinogen glycation resulting in altered structure/function properties. We investigated the effect of glucose control on fibrinogen glycation and fibrin network structure in type 2 diabetes. Blood samples were taken from twenty uncontrolled diabetic subjects at baseline to determine the levels of fibrinogen glycation and fibrin network structures. The subjects were then treated with insulin until blood glucose control was achieved before end blood samples were taken. Twenty age- and BMI-matched non-diabetic subjects were included as a reference group. The diabetic subjects had significantly higher mean fibrinogen glycation at baseline than the non-diabetic subjects (7.84 vs. 3.89 mol glucose / mol fibrinogen;p < 0.001).This was significantly reduced during the intervention (7.84 to 5.24 mol glucose / mol fibrinogen; p< 0.0002) in the diabetic group. Both groups had high mean fibrinogen concentrations (4.25 and 4.02 g/l, diabetic and non-diabetic subjects respectively). There was no difference in fibrinogen concentration, porosity, compaction and kinetics of clot formation between the diabetic subjects and non-diabetic subjects at baseline, nor were there any changes during the intervention despite the reduced fibrinogen glycation. Fibrin network characteristics correlated well with fibrinogen but not with any markers of glycaemic control. Improved glycaemic control resulted in decreased fibrinogen glycation but not fibrinogen concentration. It seems as though porosity, compaction and kinetics of clot formation are more related to fibrinogen concentration than fibrinogen glycation in this model.
Ethyl pyruvate exerts combined anti-inflammatory and anticoagulant effects on human monocytic cells
Authors: Bakhtiari Kamran , Dessing Mark , van ’t Veer Cornelis , Spek C. , Tanck Michael , Meijers Joost , van der Poll Tom , van Zoelen Marieke 
Published: December 2006

SummarySepsis is characterized by a concurrent activation of inflammation and coagulation. Recently, recombinant human activated protein C was shown to decrease mortality in patients with severe sepsis presumably due to a combined anti-inflammatory and anticoagulant effect.These promising findings led to a search for other products that influence both the inflammatory and the procoagulant response to severe infection. Ethyl pyruvate (EP) was recently identified as an experimental anti-inflammatory agent during endotoxemia and sepsis. The aim of the present study was to investigate whether EP influences coagulation besides its anti-inflammatory effects. For this we investigated the effects of EP on the expression and function of tissue factor (TF), the principal initiator of coagulation activation in sepsis, in human monocytic (THP-1) cell cultures. EP dose-dependently inhibited the production of tumor necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-1α and MIP-1β by lipopolysaccharide (LPS)-stimulated THP-1 cells at mRNA and protein level, thereby confirming its anti-inflammatory properties in this in-vitro system.In addition, EP dose-dependently attenuated the increases in TF mRNA levels,TF-protein-surface expression and cell-surface-associated TF activity in LPS-stimulated THP-1 cells. These results demonstrate for the first time that EP is a compound with combined anti-inflammatory and anticoagulant effects.
Integrin binding characteristics of the disintegrin-like domain of ADAM-15
Authors: Lu Dong , Chung Kian , Xia Min , Scully Mike , Kakkar Vijay , Lu Xinjie 
Published: December 2006

SummaryAlthough discovered as potent inhibitors of αIIbβ3-mediated platelet aggregation, snake venom disintegrins are now known to bind to other integrins according to different degrees of potency and specificity. More recently, homologues of the disintegrinlike loop have been found as a discrete domain in the ADAM family, yet the potency and specificity of each of these domains in terms of integrin binding is relatively unknown. In this present study, we have selected the disintegrin-like domain (dd) of ADAM-15 (designated as ddADAM-15), the only RGD containing domain in the ADAM family, for a structure/function study. Experimentally, the ddADAM-15 and a number of mutants in which the RGD-containing loop was substituted by cognate regions from ADAM-2, -12 and -19 were tested in terms of integrin-binding activity. For comparison with ADAM-15, an additional mutant (dddenADAM-15) was designed based upon the RGD-containing loop of snake venom dendroaspin, a disintegrin-like integrin antagonist. The results showed that ddADAM-15 is an inhibitor of platelet aggregation, though with less potency than dddenADAM-15. None of the other mutants exhibited significant inhibition of platelet aggregation. ddADAM-15 was found to have higher binding ability for α2β1 and α9β1 than the ADAM-2 derived mutant which appeared to be more selective for αVβ3 and α4β1 than either ddADAM-15 or its ADAM-19 based mutant. The integrin-binding properties of ddADAM-15 were completely abolished by point mutation within the RGD motif (R64GD→A64GD). These results suggest a more subtle contribution of this loop sequence to defining the functionality of the ADAMs compared to dendroaspin.
Performance goals for the laboratory testing of antithrombin, protein C and protein S
Authors: Haverkate Frits , Kluft Cornelis , Meijer Piet 
Published: December 2006

SummaryTo achieve a reliable analytical quality for both monitoring and diagnostic testing, laboratories need to fulfil the widely accepted analytical performance goals based on the biological variation of the analytes of testing. Not only is the short-term analytical performance, which regularly is assessed by internal quality control procedures, of importance, but also the long-term analytical performance. To assess the long-term analytical performance, data obtained from an external quality assessment programme can be used. In this study we have used the evaluation model designed by the ECAT Foundation for the assessment of the longterm analytical performance, including imprecision, bias and total analytical error. The model was applied to the data from 136 different laboratories for the assay of antithrombin (activity), protein C (activity and antigen) and protein S (activity, total and free antigen). The imprecision (median; range), reflected by the long-term analytical coefficient of variation (LCVA), was the lowest for antithrombin (7.6%; 2.6 – 43.8%) and the highest for protein S activity (17.2%; 4.3 – 88.6%). For bias and total error the same pattern was observed (antithrombin: 3.8%; 0.3 – 17.1% and 9.1%; 3.4 – 34.3%, respectively; protein S activity: 12.8%; 3.1 – 34.8% and 24.5%; 9.9 – 87.0%, respectively). For the majority of the laboratories (70 – 85%) the imprecision contributes considerably more to the total error than the bias. However the effect of the bias on the analytical quality is not negligible. Assays for antithrombin, protein C and protein S are mainly used for diagnostic testing. About 70 – 100% of the laboratories can fulfil the desirable performance goal for imprecision. The desirable performance goal for bias was reached by 50 – 95% of the laboratories. In all cases the highest numbers of laboratories fulfilling performance goals was obtained for the protein C variables. To improve the analytical quality in assays of antithrombin, protein C and protein S it is highly recommended that primarily imprecision (non-systematic failures) be suppressed. However the effect of the bias (systematic failures) on the analytical quality should not be neglected. A useful tool for determining the imprecision (LCVA) and bias is the long-term analytical performance evaluation model as used by the ECAT Foundation.
Thrombin generation, a function test of the haemostaticthrombotic system
Authors: Al Dieri Raed , De Smedt Erik , Béguin Suzette , Hemker H. 
Published: December 2006

SummaryBy the use of a fluorogenic thrombin substrate and continuous calibration of each individual sample, it is now possible to obtain a thrombin generation (TG) curve (or thrombogram) in plasma, with or without platelets, in an easy routine procedure at high throughput and with an acceptable experimental error (< 5%). Evidence is growing that the parameters of the thrombogram, and notably the area under the curve (endogenous thrombin potential, ETP), are useful in assessing bleeding-or thrombotic risk and its modification by antithrombotic-or haemostatic treatment. Available data strongly suggest that conditions (congenital, acquired, drug-induced) that increase TG all cause a thrombotic tendency and that conditions that decrease TG prevent thrombosis but, beyond a limit, cause bleeding. Diminution of TG is a common denominator of all antithrombotic treatment, including anti-platelet drugs. The thrombogram can also be used as a tool in the search for new antithrombotics and reflects the haemorrhagic or thrombotic side effects of other drugs (e.g. oral contraceptives).The thrombogram thus is a promising new approach to clinical management of bleeding and thrombotic disease as well as a tool in drug research and epidemiology. Our experience at this moment is insufficient, however, to already clearly define its limits.