Spontaneous obturator internus muscle haematoma: a new unpublished cause of ilioipelvic pain in haemophilia.

Obturator muscles haematoma are rarely reported. The most often reported cases are primary pyomyositis or posttraumatic haematomas occurring during pelvic fractures. We firstly report herein two cases of spontaneous obturator internus haematoma (OIH) in two haemophiliacs with inhibitor. Clinical data and imaging of two patients treated in our clinic are reported here according to previously defined criteria of OIH in posttraumatic situation. Both patients were children suffering from severe and moderate haemophilia A, respectively, with an inhibitor at the time of the event. The clinical feature was marked by an iliopelvic pain letting discussing hip haemarthrosis, appendicitis or iliopsoas haematoma. For both patients ultrasonography (US) failed to provide the diagnosis. Careful and repeated clinical examinations eventually lead to suspect obturator haematoma which was confirmed by abdominopelvic computed tomography (CT) and magnetic resonance imaging (MRI). Respectively, high dose of FVIII or rFVIIa regimen allowed a rapid control of the muscular bleeding in the low and high responder inhibitor patients. Spontaneous OIH may be added to the differential diagnosis of iliopelvic pain in severe forms of haemophilia. US still often performed at first in such case remains unhelpful; abdominopelvic CT or MRI should be performed to discriminate among different diagnoses, including OIH which stays probably undiagnosed.

Screening for von Willebrand disease: contribution of an automated assay for von Willebrand factor activity.

Measuring von Willebrand factor (VWF) activity is essential to the diagnosis of von Willebrand disease (VWD). The VWF activity is usually assessed based on measurement of the ristocetin cofactor (VWF:RCo). However, that test is technically challenging and has high intra- and inter-assay variabilities. The HemosIL VWF activity (VWF:AC) is a fully automated assay, recently proposed as a good alternative to VWF:RCo for VWD diagnosis. This study was undertaken to assess this new method. First, the analytical performance of VWF:AC on an automated coagulo-meter (ACLTop) was determined, and then this new method was compared with VWF:RCo and the platelet function analyzer (PFA100) for 160 patients referred for VWD screening. The VWF:AC achieved acceptable precision with within-run and between-run coefficients of variation ranging from 2.3% to 14.1%, and linearity from 10% to 100%. Despite some marked differences between VWF:AC and VWF:RCo for 10 plasmas tested, their agreement for VWD diagnosis was good. The VWF:AC had sensitivity similar to that of PFA100 (close to 100%), but better specificity (97.7% vs. 66% or 60%, depending on the cartridge used). The good analytical performance, and the sensitivity and specificity of VWF:AC to detect VWF deficiency renders it a suitable method for VWD screening. Our findings support VWF:AC use for the diagnostic work-up of VWD, paying close attention to concomitant clinical signs and bleeding score, as recommended for VWD.

Uncomplicated neurosurgical resection of a malignant glioneuronal tumour under haemostatic cover of rFVIIa in a severe haemophilia patient with a high-titre inhibitor: a case report and literature review of rFVIIa use in major surgeries.

The development of inhibitors following factor VIII replacement therapy is a serious complication in severe inherited haemophilia. Whereas significant experience, notably in orthopaedic surgery, is now obtained with the use of bypassing agents in haemophilia with high-titre inhibitor, new surgical challenges might occur due to patients' increasing life expectancy. A 56-year-old severe haemophilia A patient with a high-titre inhibitor was diagnosed for probable right temporoparietal malignant glioneuronal tumour on cerebral magnetic resonance imaging (MRI) (4 cm x 3 cm cerebromeningeal tumour with perilesional oedema and transfalcial herniation) requiring total resection. Then recombinant activated FVII (rFVIIa) was chosen as the haemostatic agent: bolus of 270 microg kg(-1) every 2 h during the first 24 h, 180 microg kg(-1) every 3, 4 and 6 h, respectively, at days 2-3, from days 4-10 and finally from days 11-15. Tranexamic acid was associated. Pre- and postoperative courses were uneventful, the surgical procedure being assessed at optimal haemostatic condition without any unusual haemorrhage on MRI controls, diffuse intravascular coagulation criteria or thromboembolic event. Intensive rFVIIa therapy has shown to be safe and effective in this first reported neurosurgery about a malignant tumour exhibiting to a high-bleeding risk notably in haemophilia with high-titre inhibitor. The use of lower doses of rFVIIa might have been possible; however, in the absence of accurate test for monitoring rFVIIa therapy, the potentially life-threatening complications of this procedure required maximum haemostasis with high rFVIIa doses.

Nonbacterial purpura fulminans and severe autoimmune acquired protein S deficiency associated with human herpesvirus-6 active replication.

Nonbacterial purpura fulminans (PF) is rare, usually follows viral infection in young children, and is characterized by specific coagulation disorders, requiring specific therapy. Following a transient rash, a 2-year-old previously healthy girl developed PF without haemodynamic impairment. Laboratory data revealed disseminated intravascular coagulation and a severe transient protein S deficiency. Antiprotein S autoantibodies and active human herpesvirus-6 (HHV6) replication were demonstrated. Purpuric skin lesions spread very rapidly despite broad-spectrum antibiotics and right leg amputation. Plasmapheresis and intravenous immunoglobulins gave complete clinical recovery and normalization of protein S level within 10 days, with progressive clearance of antiprotein S autoantibodies. Transient severe protein S deficiencies have previously been reported in patients with nonbacterial PF, usually after varicella infection. This is the first documented case of PF after HHV6 infection.

Management of antiplatelet therapy for non elective invasive procedures of bleeding complications: proposals from the French working group on perioperative haemostasis (GIHP), in collaboration with the French Society of Anaesthesia and Intensive Care Medicine (SFAR).

The French Working Group on Perioperative Haemostasis (GIHP) and the French Study Group on Haemostasis and Thrombosis (GFHT) in collaboration with the French Society of Anaesthesia and Intensive Care Medicine (SFAR) drafted up-to-date proposals on the management of antiplatelet therapy for non-elective invasive procedures or bleeding complications. The proposals were discussed and validated by a vote; all proposals could be assigned with a high strength. Emergency management of oral antiplatelet agents (APA) requires knowledge on their pharmacokinetic/pharmacodynamics parameters, evaluation of the degree of the alteration of haemostatic competence and the associated bleeding risk. Platelet function testing may be considered. When APA-induced bleeding risk may worsen the prognosis, measures should be taken to neutralise antiplatelet therapy by considering not only the efficacy of available means (which can be limited for prasugrel and even more for ticagrelor) but also the risks that these means expose the patient to. The measures include platelet transfusion at the appropriate dose and haemostatic agents (tranexamic acid; rFVIIa for ticagrelor). When possible, postponing non-elective invasive procedures at least for a few hours until the elimination of the active compound (which could compromise the effect of transfused platelets) or if possible a few days (reduction of the effect of APA) should be considered.

Agreement between factor XIII activity and antigen assays in measurement of factor XIII: A French multicenter study of 147 human plasma samples.

INTRODUCTION: Factor XIII (FXIII) deficiency is a rare hemorrhagic disorder whose early diagnosis is crucial for appropriate treatment and prophylactic supplementation in cases of severe deficiency. International guidelines recommend a quantitative FXIII activity assay as first-line screening test. FXIII antigen measurement may be performed to establish the subtype of FXIII deficiency (FXIIID) when activity is decreased. METHODS: The aim of this multicenter study was to evaluate the analytical and diagnostic levels of performance of a new latex immunoassay, K-Assay® FXIII reagent from Stago, for first-line measurement of FXIII antigen. Results were compared to those obtained with the Berichrom® FXIII chromogenic assay for measurement of FXIII activity. Of the 147 patient plasma samples, 138 were selected for analysis. RESULTS: The accuracy was very good, with intercenter reproducibility close to 7%. Five groups were defined on FXIII activity level (<5% (n = 5), 5%-30% (n = 23), 30%-60% (n = 17), 60%-120% (n = 69), above 120% (n = 24)), without statistical differences between activity and antigen levels (P value >0.05). Correlation of the K-Assay® with the Berichrom® FXIII activity results was excellent (r = 0.919). Good agreement was established by the Bland and Altman method, with a bias of +9.4% on all samples, and of -1.4% for FXIII levels lower than 30%. One patient with afibrinogenemia showed low levels of Berichrom® FXIII activity but normal antigen level and clot solubility as expected. CONCLUSIONS: The measurement of FXIII antigen using the K-Assay® is a reliable first-line tool for detection of FXIII deficiency when an activity assay is not available.

Diagnostic score for heparin-induced thrombocytopenia after cardiopulmonary bypass.

Heparin-induced thrombocytopenia (HIT) occurs in nearly 3% of patients treated with heparin after cardiopulmonary bypass (CPB). HIT carries a risk of severe thrombotic complications, and must be diagnosed rapidly. To identify simple criteria for estimating the probability of HIT after CPB, we retrospectively analyzed the files of 84 patients with suspected HIT after CPB and we analyzed the usefulness of several variables collected at the time of HIT suspicion to estimate HIT probability. HIT was confirmed in 35 cases and ruled out in 49 cases, on the basis of a platelet increment after heparin withdrawal, detection of heparin-dependent antibodies, and absence of other clear cause of thrombocytopenia. A biphasic platelet count from CPB to the first day of suspected HIT, an interval of >/= 5 days from CPB to the first day of suspected HIT, and a CPB duration of

Different abilities of thrombin receptor activating peptide and thrombin to induce platelet calcium rise and full release reaction.

Synthetic peptides (TRAP or Thrombin Receptor Activating Peptide) corresponding to at least the first five aminoacids of the new N-terminal tail generated after thrombin proteolysis of its receptor are effective to mimic thrombin. We have studied two different TRAPs (SFLLR, and SFLLRN) in their effectiveness to induce the different platelet responses in comparison with thrombin. Using Indo-l/AM-labelled platelets, the maximum rise in cytoplasmic ionized calcium was lower with TRAPs than with thrombin. At threshold concentrations allowing maximal aggregation (50 microM SFLLR, 5 microM SFLLRN and 1 nM thrombin) the TRAPs-induced release reaction was about the same level as with thrombin, except when external calcium was removed by addition of 1 mM EDTA. In these conditions, the dense granule release induced by TRAPs was reduced by over 60%, that of lysosome release by 75%, compared to only 15% of reduction in the presence of thrombin. Thus calcium influx was more important for TRAPs-induced release than for thrombin-induced release. At strong concentrations giving maximal aggregation and release in the absence of secondary mediators (by pretreatment with ADP scavengers plus aspirin), SFLLRN mobilized less calcium, with a fast return towards the basal level and induced smaller lysosome release than did thrombin. The results further demonstrate the essential role of external calcium in triggering sustained and full platelet responses, and emphasize the major difference between TRAP and thrombin in mobilizing [Ca2+]i. Thus, apart from the proteolysis of the seven transmembrane receptor, another thrombin binding site or thrombin receptor interaction is required to obtain full and complete responses.

A study of platelet functions with a new analyzer using high shear stress (PFA 100) in patients undergoing coronary artery bypass graft.

Platelet dysfunction can be a major factor in excessive bleeding following cardiopulmonary bypass (CBP). A rapid, specific and sensitive method to identify platelet dysfunction would be a useful tool for identifying patients at an increased risk of bleeding. The ability of PFA100, an in vitro bleeding test, to predict increased bleeding risk linked to platelet dysfunction was tested in 146 patients undergoing primary coronary artery bypass graft. Blood samples were taken the day before surgery, and 15 min and 5 h after heparin neutralization. The preoperative closure times (CT), i.e. the time required for platelets in citrated whole blood to occlude an aperture cut into a membrane coated with collagen plus either epinephrine (CTEPI) or adenosine diphosphate (CTADP) were longer in blood-group-O patients than in patients with other groups. The 15 min postoperative values were significantly longer from preoperative values essentially owing to CBP-induced hemodilution. Interestingly, 5 h after CBP, a significant reduction in CT values probably reflected platelet hyperaggregability. No correlation was found between calculated blood loss (CBL) and either preoperative or postoperative PFA values.

Importance of the FcgammaRIIa-Arg/His-131 polymorphism in heparin-induced thrombocytopenia diagnosis.

Heparin-induced thrombocytopenia (HIT) involves heparin-dependent antibodies which induce platelet activation. In the present study, we searched for a relationship between the polymorphism of the Fc receptor (FcgammaRIIa) and the development of HIT. In this purpose, all the donors were genotyped for their FcgammaRIIA and HIT patients were selected on the basis of at least one positive answer by 14C-serotonin release assay (SRA). The frequency distribution of the FcgammaRIIa polymorphism in the HIT patient group was similar to that observed in the healthy control group. Moreover, a statistical analysis taking into account our results and those of 3 previously published studies, suggested at most only a weak association between HIT and the FcgammaRIIa-131 polymorphism. Laboratory tests used to diagnose HIT rely on the activation of normal donor platelets but fail to detect every HIT positive patient. We determined the role of FcgammaRIIa-131 polymorphism on the reactivity of control platelets to HIT plasmas. When control platelet FcgammaRIIa-131 was of Arg/Arg form, only 47% of the HIT plasmas were positive by SRA, compared to 81% and 74% for His/His or His/Arg forms, respectively. We also compared the level of anti PF4/heparin antibodies in the HIT plasmas with the response obtained by SRA. The mean anti PF4/heparin antibodies level in HIT plasma was significantly lower in negative SRA than in positive tests when using control platelets from FcgammaRIIa-Arg/Arg 131 and heterozygous donors. Thus, the variability of control platelets to respond to HIT plasmas in the SRA test is related to both the FcgammaRIIa-131 polymorphism, and to the amount of anti PF4/heparin antibodies.

Thrombomodulin modulates the mitogenic response to thrombin of human umbilical vein endothelial cells.

Thrombin interacts with its receptor and thrombomodulin on endothelial cells. We evaluated the respective roles of these two proteins on human umbilical vein endothelial cell (HUVEC) growth by comparing thrombin, S195A (a mutant thrombin in which the serine of the charge stabilizing system had been replaced by alanine), and the receptor activating peptide (TRAP). Thrombin and TRAP induced DNA synthesis (half maximal cell proliferation with 5 nM and 25 microM, respectively), whereas S195A thrombin was inactive, inferring that growth is mediated through the thrombin receptor. Surprisingly, cells stimulated by TRAP exhibited a maximal proliferation twice greater than that obtained with thrombin. Combination of thrombin and TRAP resulted in a mitogenic response higher than by thrombin alone, but lower than by TRAP alone. The role of thrombomodulin was evaluated by adding an anti-thrombomodulin antibody, which prevents formation of the thrombin-thrombomodulin complex. Antibody did not interfere with cell proliferation induced by TRAP, but enhanced that induced by thrombin. We conclude that formation of the thrombin-thrombomodulin complex restrains HUVEC proliferation mediated through the thrombin receptor.

A new approach in the study of the molecular and cellular events implicated in heparin-induced thrombocytopenia. Formation of leukocyte-platelet aggregates.

Heparin-induced thrombocytopenia (HIT), a relatively common complication of heparin therapy, results of platelet activation, via the receptor for the Fc domain of IgG (FcgammaRIIa), by heparin-dependent-antibodies, commonly directed against the heparin-platelet factor 4 (H-PF4) antigenic complex. Our strategy was to use whole blood allowing the study of leukocyte-platelet interactions. Experiments were performed with blood from healthy donors incubated with HIT patients' plasma and different concentrations of heparin. We showed that 75% of the HIT patients' plasma induced the formation of leukocyte-platelet-aggregates in a heparin-dependent-manner. The formation of leukocyte-platelet-aggregates induced by HIT plasma in the presence of heparin was (i) independent of the healthy blood donor FcgammaRIIa polymorphism, (ii) correlated with the levels of anti H-PF4 IgG antibodies contained in the patients' plasma, and to a lesser extent to anti H-PF4 IgM antibodies, and (iii) was mediated by P-selectin. This report opens new prospects in the study of the molecular and cellular events implicated in HIT.

Transverse fluctuations of single DNA molecules attached at both extremities to a surface.

We present a simple method to stretch DNA molecules close to a surface without any chemical modification of either the molecules or the surface. By adjusting the pH of the solution, only the extremities of DNA molecules are tethered to a glass coverslip made hydrophobic, while stretching is achieved using a hydrodynamic flow. These extended molecules provide a very favorable template for DNA-protein interaction studies by purely optical means. Pursuing these experiments requires first a full characterization of the thermally driven fluctuations of the tethered DNA molecules. For this purpose, these fluctuations were recorded by fluorescence microscopy and were analyzed in terms of normal modes. Our experimental results are well described by a model accounting for the nonlinear elastic behavior of the chain. Remarkably, the proximity of the molecules to a rigid surface does not alter the main features of their dynamics, and our results are in agreement with previous studies on extended DNA in viscous solutions.

[Cellular receptor of thrombin]. / Le récepteur cellulaire de la thrombine.

Thrombin is a serine protease able to evoke biological responses from a variety of cells, including platelets, endothelial cells, fibroblasts and smooth muscle cells. The structure of the thrombin receptor present in the human megakaryoblastic cell line and in hamster fibroblasts has recently been deduced by expression in the Xenopus laevis oocyte. The cloned receptor is a new member of the seven transmembrane domain receptor family that interacts with G proteins. A large amino-terminal extracellular extension has a cleavage site for thrombin (Leu Asp Pro Arg/Ser Phe Leu Leu,/representing the cleavage site). Thrombin cleaves at this site, unmasking a new amino terminus, that functions like a ligand, binding to an as yet undefined site and eliciting receptor activation. Peptides similar to a new amino terminus created after cleavage are able to mimic thrombin cellular effects. These agonist peptides are used to analyse the role of the cloned receptor in the thrombin-specific response.

[Heparin induced autoimmune thrombocytopenia: assessment of a rapid functional assay]. / La thrombopénie immunoallergique induite par l'héparine: evaluation d'un test fonctionnel rapide.

Heparin-induced thrombocytopenia (HIT) diagnosis is often difficult. Depending on the patients, the thrombocytopenia could be due to various causes. Despite their poor sensitivity and specificity, biological tests are necessary to clarify the diagnosis. In 1985, a new heparin-induced platelet aggregation assay was described that consists in determining the percentage of aggregated platelets by using an automated cell counter. Plasma samples from 18 patients with a definite HIT were tested with this quick easy-to-perform HIT diagnosis test. Positive results were obtained with 11 plasma (61%) when the test was performed with platelets from 3 different healthy volunteers (control platelets). As for the other functional tests, results are depending on control platelets and sensitivity seems to be increased when control platelets FcgammaRIIa-131 polymorphism was of His/His (but difference is not significant). In emergency situation, it is difficult to perform a functional test with control platelets from several healthy donors, and it is even more difficult to select volunteers on their FcgammaRIIa-131 polymorphism. In conclusion, in spite of its practicability, the test is not reliable to help in the rapid diagnosis of HIT. Indeed, 7 patients of 18 (39%) with definite HIT have been found negative with this test.

[Monitoring of heparin therapy during extracorporeal bypass: what are the remaining questions?]. / Surveillance de l'anticoagulation des circulations extracorporelles par l'héparine non fractionnée: quels sont les problèmes non résolus?

Cardiac surgery with extracorporeal circulation induces major alterations of haemostasis and requires high level of anticoagulation, usually achieved by unfractionated heparin infusion. Optimization of anticoagulant regimen, through adapted biological monitoring, can probably improve postoperative course, at least for postoperative haemostatic status. Despite increasing knowledge on extracorporeal circulation-induced haemostatic abnormalities and the development of new biological devices for heparin monitoring, the optimal level of anticoagulation remains matter of debate, as well as the monitoring procedures. This critical review presents the current available data on heparin anticoagulation and monitoring in this specific context, and underlines the pending issues about anticoagulation management during extracorporeal bypass.