bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of an ELISA for Autoantibodies to Prothrombin Showing their Prevalence in Patients with Lupus Anticoagulants
Authors: Arvieux J , Darnige L , Caron C , Reber G , Bensa J C , Colomb M G 
Published: July 2018

SummarySome lupus anticoagulants (LA) have been shown to be directed against phospholipid-bound prothrombin. While developing an ELISA to detect anti-prothrombin autoantibodies in patient serum or plasma, no or very low signal was observed using human prothrombin immobilized on plain polystyrene plates. In contrast, the same LA-positive samples bound specifically to prothrombin coated on γ-irradiated plates, depending on the radiation dose, in the absence of added calcium and phospholipid. Optimization of the assay required the addition of 0.1% Tween 20 to the buffers. Antibody specificity for immobilized prothrombin was ascertained by competition using liposome-bound prothrombin, since fluid-phase prothrombin competed poorly. Seventy-seven of 139 patients (55.4%) with LA related to a variety of underlying diseases possessed anti-prothrombin antibodies (27 IgG, 35 IgM and 15 both isotypes), either isolated or more often associated with anti-(β2 glycoprotein I (β2GPI) antibodies. These included 67-71% of the patients with systemic lupus erythematosus and related disorders, primary antiphospholipid antibody syndrome or drug-induced LA (autoimmune groups), but only 19-20% of those with infection or malignancy (p <0.001). As previously shown for anti-β2GPI antibodies, IgG2 was the predominant IgG subclass reactive with prothrombin. Thus, autoimmune patients with LA have a high incidence of antibodies to β2GPI and prothrombin, the binding of which could similarly require high antigen density and/or exposure of cryptic epitopes resulting from protein interaction with an irradiated (i. e. more anionic) polystyrene surface.
Ultrastructural Detection of Surface Exposed Phosphatidylserine on Activated Blood Platelets
Authors: Stuart M C A , Bevers E M , Comfurius P , Zwaal R F A , Reutelingsperger C P M , Frederik P M 
Published: July 2018

SummaryPhosphatidylserine (PS) is normally restricted to the inner leaflet of the plasma membrane of cells (including blood platelets). Upon cell activation PS may become exposed to the outer surface of the cell. Cell membranes with surface exposed PS at the outside form a catalytic surface for coagulation reactions. When platelets are activated with ionophore or with thrombin in combination with thapsigargi, calcium induced scrambling of phospholipids takes place, resulting in PS exposure. Concomitant with PS exposition structural changes take place. On resting and activated platelets we combined the immunocytochemical detection of surface exposed PS with (ultra)structural information. Blood platelets were activated in the presence of annexin V, a protein which binds to PS in the presence of Ca2+. Annexin V was found to bind to lipid bilayers containing more than 5 mole % PS as estimated by binding of fluorescent-labelled annexin V to liposomes with varying PS concentrations. After vitrification, freeze-substitution and embedding of the platelets, annexin V was located on ultra thin sections, as detected by an anti-annexin V antibody and gold labelled protein A. Upon activation, the platelets show two different forms; irregular platelets with unchanged cytoplasm and round cells with apparently diluted cytoplasm. Activation with ionophore initially resulted in both forms, but after ten minutes only round platelets with diluted cytoplasm were observed. Both forms of these platelets as well as the microvesicles were found to be annexin V positive. However upon activation with thrombin in combination with thapsigargin, only the round cells with diluted cytoplasm and microvesicles were annexin V positive, whereas platelets with unchanged cytoplasm, even when microvesicles are present, are negative for annexin V.
Effects of Heparin and Hirudin on Thrombin Generation and Platelet Aggregation after Intrinsic Activation of Platelet Rich Plasma
Authors: Gallistl Siegfried , Muntean Wolfgang , Leis Hans Jörg 
Published: July 2018

SummaryThe effects of unfractionated heparin (UH) and recombinant hirudin (rH) on prothrombin activation, free thrombin generation, and platelet aggregation induced by endogenously generated thrombin after intrinsic activation of platelet rich plasma were compared. Free thrombin generation and platelet aggregation were assessed simultaneously by delaying fibrinogen polymerisation with GPRP.UH more effectively inhibited prothrombin activation and free thrombin generation than rH. Increasing concentrations of rH had hardly any effect on the peak amount of free thrombin, while in the presence of 400 nM UH only traces of free thrombin were detected. Comparison of TAT and THC (thrombin-hirudin complex) generated until the onset of platelet aggregation on a molar basis showed that much more thrombin was inactivated in the presence of rH than in plasma containing UH. The explosive generation of free thrombin in hirudinized plasmas was accompanied by a markedly steeper aggregation curve as compared to heparinized plasmas. The generation of thromboxane B2 was markedly delayed in the presence of UH but not influenced in the presence of rH.Our results suggest that UH is more effective than rH in inhibiting prothrombin activation after intrinsic activation of platelet rich plasma, while rH prevents clotting more by direct inactivation of already generated thrombin. The inability of even high concentrations of rH to prevent the explosive generation of free thrombin might contribute to the observed inefficiency of rH to inhibit platelet aggregation.
A Novel Nonsense Mutation Associated with an Exon Skipping in a Patient with Hereditary Protein S Deficiency Type I
Authors: Okamoto Yoshihiro , Yamazaki Tomio , Katsumi Akira , Kojima Tetsuhito , Takamatsu Junki , Nishida Mikio , Saito Hidehiko 
Published: July 2018

SummaryThe genetic defect in a patient with hereditary type I protein S (PS) deficiency was investigated. All the exons and intron-exon junctions of the patient’s PS gene were amplified by PCR and subjected to heteroduplex screening. Only the PCR product of exon 4 revealed heteroduplex bands. A novel nonsense mutation, Ser62 (TCA) to Stop (TGA) was found in exon 4. RT-PCR detected the aberrant mRNA in the patient’s platelets, which was markedly reduced in amount and lacked the region of exon 4, suggesting that the nonsense mutation affected the mutated mRNA metabolism and induced exon skipping. The skipping of exon 4 causes an in-frame deletion of 29 amino acids which just construct the thrombin-sensitive region of the PS molecule. The loss of such an important domain as well as the quantitative decrease in the mutated mRNA appear to be responsible for the type I PS deficiency in this patient.
Risk Factors for Bleeding during Treatment of Acute Venous Thromboembolism
Authors: Wester Jos P J , de Valk Harold W , Nieuwenhuis Karel H , Brouwer Catherine B , van der Graaf Yolanda , Meuwissen Otger J A Th , Hart Herman C , Sixma Jan J , Dirk Banga Jan 
Published: July 2018

Summary
Objective: Identification of risk factors for bleeding and prospective evaluation of two bleeding risk scores in the treatment of acute venous thromboembolism.
Design: Secondary analysis of a prospective, randomized, assessor-blind, multicenter clinical trial.
Setting: One university and 2 regional teaching hospitals.
Patients: 188 patients treated with heparin or danaparoid for acute venous thromboembolism.
Measurements: The presenting clinical features, the doses of the drugs, and the anticoagulant responses were analyzed using univariate and multivariate logistic regression analysis in order to evaluate prognostic factors for bleeding. In addition, the recently developed Utrecht bleeding risk score and Landefeld bleeding risk index were evaluated prospectively.
Results: Major bleeding occurred in 4 patients (2.1%) and minor bleeding in 101 patients (53.7%). For all (major and minor combined) bleeding, body surface area ≤2 m2 (odds ratio 2.3, 95% Cl 1.2-4.4; p = 0.01), and malignancy (odds ratio 2.4, 95% Cl 1.1-4.9; p = 0.02) were confirmed to be independent risk factors. An increased treatment-related risk of bleeding was observed in patients treated with high doses of heparin, independent of the concomitant activated partial thromboplastin time ratios. Both bleeding risk scores had low diagnostic value for bleeding in this sample of mainly minor bleeders.
Conclusions: A small body surface area and malignancy were associated with a higher frequency of bleeding. The bleeding risk scores merely offer the clinician a general estimation of the risk of bleeding. In patients with a small body surface area or in patients with malignancy, it may be of interest to study whether limited dose reduction of the anticoagulant drug may cause less bleeding without affecting efficacy.
More Effective Suppression of Hemostatic System Activation in Patients Undergoing Cardiac Surgery by Heparin Dosing Based on Heparin Blood Concentrations rather than ACT
Authors: Despotis George J , Heinrich Joist J , Hogue Charles W , Alsoufiev Alexander , Joiner-Maier D , Santoro Samuel A , Spitznagel Edward , Weitz Jeffrey I , Goodnough Lawrence T 
Published: July 2018

SummaryThis study was designed to determine whether the maintenance of higher than usual patient-specific heparin concentrations during cardiopulmonary bypass (CPB) was associated with more effective suppression of hemostasis system activation.Thirty-one patients scheduled for repeat cardiac sugery or combined procedures (i.e., coronary revascularization + valve repair/replacement) were consented and enrolled in this study. All patients received porcine heparin and protamine and were randomly assigned to monitoring of anticoagulation by either celite ACT alone (Control, n = 16) or by kaolin ACT combined with on-site measurements of whole blood heparin concentration (Intervention, n = 15). Blood specimens collected before administration of heparin, before weaning from CPB and after administration of protamine were analyzed with a battery of coagulation assays.Patients in the intervention cohort received appreciably greater heparin doses than control patients, resulting in higher anti-Xa heparin levels at the end of CPB. Fibrinopeptide A and D-dimer levels were higher in the control group before discontinuation of CPB. Percent decrease during CPB were greater in the control group for factors V and VIII, fibrinogen and antithrombin III. Percent decrease in complement 3 was greater in the control group after protamine and bleeding times measured in the Intensive Care Unit were significantly more prolonged in this group.Maintenance of higher patient-specific heparin concentrations during CPB more effectively suppresses excessive hemostatic system activation than do standard heparin doses chosen based on measurement of ACT. These findings may explain, at least in part, the significant reduction in perioperative blood loss and blood product use when higher heparin concentrations are maintained.
Pathogenetic Analysis of Five Cases with a Platelet Disorder Characterized by the Absence of Thromboxane A2(TXA2)-Induced Platelet Aggregation in Spite of Normal TXA2 Binding Activity
Authors: Fuse Ichiro , Hattori Akira , Mito Masao , Higuchi Wataru , Yahata Kazuaki , Shibata Akira , Aizawa Yoshifusa 
Published: July 2018

SummaryFive patients with mild bleeding tendencies characterized by defective thromboxane A2 (TXA2)-induced platelet aggregation are reported. The platelets of all the patients had the ability to bind exogenous TXA2. Bleeding time was markedly prolonged in one patient. In three of the five patients, synthetic TXA2 mimetic (STA2)-induced platelet responses, including IP3 formation, Ca2+ mobilization, phosphatidic acid formation and GTPase activities were selectively defective, suggesting impaired coupling between the TXA2 receptor and phospholipase C activation. However, in the remaining two patients, these responses were all within normal limits. This suggests that the defective site of this type of platelet disorder is heterogenous and that signaling mechanisms other than the TXA2 receptor-phospholipase C pathway are also involved in TXA2-induced platelet aggregation.
Autoimmune Antiphospholipid Antibodies Are Directed against a Cryptic Epitope Expressed when β2-Glycoprotein I Is Bound to a Suitable Surface
Authors: Pengo Vittorio , Biasiolo Alessandra , Fior Maria Grazia 
Published: July 2018

SummaryThe antiphospholipid antibodies (aPL) present in autoimmune disorders are associated with thromboembolic episodes, and their binding to phospholipids (PL) is mediated by a plasma cofactor, β2-glycoprotein I (β2GPI). Both PL and β2GPI seem necessary for binding, thus indicating that the two components comprise the epitope against which aPL are directed. Using an anti-β2GPI antibody ELISA with the antigen adsorbed onto polyvinylchloride (PVC) plates, we detected high antibody titres in 12 out of 12 plasmas from patients with the antiphospholipid syndrome. No or very low positivity was obtained when the same ELISA was carried out in polystyrene (PST) plates, while an increasing positivity was found when processed (i.e. more hydrophilic) or COOH-surface PST plates were used. When (β2GPI dependent IgG-aPL were purified using agarose-immobilized cardio- lipin, 4 out of 4 preparations were highly positive in anti-β2GPI antibody ELISA using PVC plates, while β2GPI was not fully recognized by aPL-IgG when adsorbed onto PST plates. These findings demonstrate that aPL are, in fact, anti-β2GPI antibodies directed against a cryptic epitope which is expressed when β2GPI is bound to anionic phospholipid, or another suitable surface.
Tissue Factor Activity of Syncytiotrophoblast Plasma Membranes and Tumoral Trophoblast Cells in Culture
Authors: Reverdiau P , Jarousseau A C , Thibault G , Khalfoun B , Watier H , Lebranchu Y , Bardos P , Gruel Y 
Published: July 2018

SummaryDuring pregnancy, important modifications of hemostasis occur resulting in mothers in hypercoagulability and the role of placental cells such as trophoblast cells has been hypothesized. In this study, we first showed that syncytiotrophoblast plasma membranes, isolated from normal human placenta, expressed a strong tissue factor (TF) activity. We then studied TF activity of two continuous trophoblast cell lines (JEG-3 and BeWo) in comparison to human umbilical vein endothelial cells (HUVEC) and transformed human endothelial cells (ECV-304). TF assays were performed on intact detached confluent cells. Unstimulated JEG-3 and BeWo cells exhibited a very high TF activity which slightly increased after 2 to 4 h TNF-α stimulation. In contrast, HUVEC and ECV-304 had a lower basal TF activity which was mainly inducible by TNF-a, with a maximum effect after 4 to 6 h stimulation. For both cell types, TF activity was decreased to basal value after 16-hour TNF-α stimulation. These results support that trophoblast cells are able to express TF but the involvement of this property in the hemostatic physiological changes observed during pregnancy, remains to be demonstrated.
The APTT Monitoring of Heparin - The ISTH/ICSH Collaborative Study
Authors: Poller L , Van der Velde E A 
Published: July 2018

SummaryIn an international collaborative study three candidate reference and the local APTT reagent have been tested with lyophilized plasmas containing heparin added in vitro and fresh plasmas from heparinized patients to determine whether it was possible to standardize APTT heparin monitoring.The APTT responses of patients with thrombosis were much less to the same concentrations of heparin so only these plasmas were used to calibrate the reagents.A calibration constant (b) was determined for each local APTT system from the orthogonal regression slope of the patients’ and normals’ plasmas. Although the calibration was based on relatively limited numbers of patients’ plasmas the results gave no consistent indication that this method of analysis with the reference preparations was incorrect. Two of the three candidate reference reagents performed almost equally well and one of these reagents is recommended as the APTT reference preparation. Use of a single b value for a brand of reagent for all laboratories is not advised. Each laboratory must perform its own local calibration. The adoption of a reference APTT reagent together with the use of orthogonal regression analysis would be a useful step to initiate APTT heparin monitoring standardization and to develop safe and effective local therapeutic ranges.
Desmin 370, a Low Molecular Weight Dermatan Sulfate, Reduces the Weight of Preformed Thrombi in Rats Made Afibrinogenemic by Ancrod
Authors: Barbanti Miriam , Calanni Fiorella , Marchi Egidio , Semeraro Nicola , Colucci Mario 
Published: July 2018

SummaryDesmin 370 (D370), a low molecular weight dermatan sulfate, has been shown to induce a marked reduction of the weight of preformed venous thrombi in rats and rabbits by mechanisms that appeared largely independent of inhibition of thrombus accretion. In order to provide further support for such a mechanism, we exploited the defibrinating capacity of ancrod to obtain a thrombosis model characterized by the lack of thrombus growth and thus sensitive only to agents promoting thrombus lysis. Thrombus formation in anesthetized rats was induced by vena cava ligature. Injection of ancrod (5 U/kg) 5 h after induction of venous stasis caused a more than 95% reduction in plasma fibrinogen and prevented thrombus accretion as indicated by the lack of thrombus weight increase during the 3h experimental period (12.2 ° 0.6 vs 14.5 ° 1 as compared to 12.6 ° 0.6 vs 19.6 ° 0.8, p <0.01, in control rats) and by the almost complete (>90%) inhibition of125I- fibrin(ogen) binding to thrombi. Moreover, when ancrod was given 1 h before vena cava ligature, no thrombi were formed within 2 h whereas at the same time interval visible thrombi were present in all control rats. Administration of D370 (10 mg/kg) to thrombus bearing rats, 1 h after induction of afibrinogenemia, resulted in a significant reduction in thrombus weight (43% after 2h, p <0.01) which was only slightly lower than that recorded in normofibrinogenemic rats (54%). Enhancement of plasma fibrinolytic activity by ancrod had no influence on thrombus lysis and was not at all affected by administration of D370. These data provide additional and more direct evidence that D370 may promote thrombus lysis independently of inhibition of thrombus accretion.
Fibrin Polymerization Defect in HIV-infected Patients-Evidence for a Critical Role of Albumin in the Prolongation of Thrombin and Reptilase Clotting Times
Authors: Toulon Pierre , Frere Elyane , Bachmeyer Claude , Candia Nathalie , Blanche Philippe , Sereni Daniel , Sicard Didier 
Published: July 2018

SummaryThrombin clotting time (TCT) and reptilase clotting time (RCT) were found significantly prolonged in a series of 72 HIV-infected patients drawn for routine coagulation testing. Both TCT and RCT were highly significantly correlated with albumin (r = -0.64, and r = -0.73 respectively, p<0.0001). TCT and RCT were significantly higher (p<0.0001) in a series of 30 other HIV-infected patients selected on their albumin level below 30.0 g/l (group l) than in 30 HIV-infected patients with albumin level above 40.0 g/l or in 30 HIV-negative controls; the two latter groups were not different. In vitro supplementation of plasma from group 1 patients with purified human albumin up to 45.0 g/l (final concentration) lead to a dramatic shortening effect on both TCT and RCT, which reached normal values. The TCT and RCT of the purified fibrinogen solutions (2.0 g/l final concentration) were not different in the three groups, and normal polymerization curves were obtained in all cases. This further ruled out the presence of any dysfibrinogenemia in the plasma from group 1 patients. Using purified proteins, highly significant correlations were demonstrated between the albumin concentration and the prolongations of both TCT and RCT, which were of the same magnitude order than those found in the patients plasma. These results suggest that hypo-albuminemia is responsible for the acquired fibrin polymerization defect reported in HIV-infected patients. The pathophysiological implication of the low albumin levels was suggested by the finding of decreased albumin levels (associated with prolonged TCT and RCT) in a small series of the eight HIV-infected patients who developed thrombotic complications.
One Month Follow-up of Haemostatic Variables in Patients Undergoing Aortocoronary Bypass Surgery
Authors: Mannucci L , Gerometta P S , Mussoni L , Antona C , Parolari A , Salvi L , Biglioli P , Tremoli E 
Published: July 2018

SummaryIt is already known that activation of the coagulation and fibrinolytic system occurs in patients undergoing cardiopulmonary bypass (CPB). We have thus studied twenty patients (10 treated with aprotinin during CPB and 10 untreated) both during the intraoperative period and during thirty days follow up. In untreated patients D-dimer levels increased 4-fold during CPB and the levels were above baseline for the whole follow up (p<0.0001). D-dimer levels were reduced in aprotinin treated patients in comparison to untreated patients (p = 0.0172); levels then gradually increased to the values of the untreated patients over the following 24 h later and remained higher during the thirty day follow up. The behavior of haemostatic variables in the 24 h after CPB did not vary between untreated and aprotinin treated patients. In particular, five minutes after protamine sulphate administration, levels of F1 + 2 and TAT rose significantly (p = 0.0054, p = 0.0022 respectively), whereas fibrinogen significantly decreased (p<0.0001) and PAI-1 antigen levels were reduced. Two days after CPB the concentrations of F1 + 2 and TAT lowered, whereas fibrinogen and PAI-1 antigen levels increased. On the 5th, 8th and 30th days after CPB, F1 + 2 and TAT levels remained higher than those reported at baseline in both groups of patients, whereas fibrinogen levels increased over basal levels in aprotinin treated patients only.Thus, in addition to the activation of the coagulation and fibrinolytic system occurring during the intraoperative period, in patients undergoing CPB, there are alterations of haemostatic variables up to thirty days from surgery.
Early Markers of Blood Coagulation and Fibrinolysis Activation in Argentine Hemorrhagic Fever
Authors: Heller M V , Marta R F , Sturk A , Maiztegui J I , Hack C E , ten Cate J W , Molinas F C 
Published: July 2018

SummaryJunin virus, an arenaviridae, is the etiological agent of Argentine hemorrhagic fever. In addition to thrombocytopenia, patients present several alterations in both the blood coagulation and the fibrinolytic system, but diffuse intravascular coagulation could not be demonstrated. To investigate further the activation status of the two systems, levels of thrombin-antithrombin complexes (TAT), prothrombin fragment 1+2, protein C, total and free protein S, C4bBP, antithrombin III, t-PA, PAI-1 and D-dimer were measured. Fourteen patients with a confirmed diagnosis of Argentine hemorrhagic fever were included in the study, 2 were severe, 3 moderate and 9 mild clinical cases, but hemorrhages were slight throughout. Blood samples were collected for 6 consecutive days on admission and on remission. At admission TAT and F1+2 levels were increased in 13/14 patients, reaching 0.33 nM (0.06-0.87) and 2.16 nM (0.96-6.5), respectively. PC was low in 4 cases, fPS in 6 and tPS in 2, whereas C4bBP and ATIII values were within normal range. t-PA and D-dimer levels were high in 11/14 patients, reaching 20 ng/ml (2.7-106) and 1660 ng/ml (877-3780) respectively, while PAI-1 was considerably increased in the 2 severe cases and normal in the remainder. These results suggest low level though persistent process of blood coagulation and fibrinolysis activation in this viral hemorrhagic disease. We believe these abnormalities may lead to the well described bleeding manifestations in these patients.