bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Efficacy and Safety of Oral Anticoagulation in Patients with Cancer
Authors: Bona Robert D , Sivjee Khalil Y , Hickey Amy D , Wallace Donna M , Wajcs Selby B 
Published: July 2018

Summary
Objectives: To compare the complication rate (bleeding and thrombosis) of oral anticoagulation in a cohort of patients with cancer to a cohort without cancer
Design: Prospective cohort study
Setting: Outpatient anticoagulation clinic in a community hospital
Patients: Consecutive patients enrolled in an anticoagulation clinic: 44 with cancer, 64 without cancer
Interventions: Patients received prophylactic doses of Warfarin (target INR 2–3 in the majority of instances) and complication rates were assessed
Measurements: Major bleeding (strictly defined), minor bleeding, recurrent thrombosis, proportion of time with therapeutic INR, frequency of clinic visits
Results: The rates of major bleeding, minor bleeding, and recurrent thrombosis were not statistically significantly different in the two groups of patients. Therapeutic INR’s were more difficult to sustain in the cancer patients as compared to the non-cancer patients (43.3% vs 56.9%, p <0.0001). There was a non significant trend towards more frequent monitoring for the cancer patients compared with the noncancer patients (4.6 vs 3.5 visits per treatment month, p = 0.14)
Conclusions: Oral anticoagulation is safe and effective in the patient with cancer. It is more difficult to sustain a therapeutic INR in the cancer patients and they may need more frequent monitoring to achieve a low complication rate
Inversion of Intron 22 in Isolated Cases of Severe Hemophilia A
Authors: Baiget Montserrat , Tizzano Eduardo F , Domènech Montserrat 
Published: July 2018

SummaryInversion involving intron 22 is the commonest type of mutation causing severe hemophilia A (HA). We investigated 15 families with isolated cases and 5 families with two or three brothers as the only affected members with hemophilia A, in order to determine the carrier status of the mothers, the origin of the mutation and the presence of germinal mosaicism. Our results show that all mothers tested were carriers of the inversion. In addition, three families whose unique hemophilic member was not available for analysis, were screened for the inversion. In one of these last families, the mother was diagnosed as a carrier and her sister and her niece as non-carriers. DNA haplotype analysis in 8 families with grandparents available for study demonstrated that the inversion originated almost exclusively in male germ cells. These findings have important relevance for genetic counselling in families with an isolated case or to exclude germinal mosaicism. Inversion analysis should constitute the first step in molecular diagnosis of severe hemophilia A.
Occlusive Thrombus Formation on Indwelling Catheters: In Vitro Investigation and Computational Analysis
Authors: Friedrich Peter , Reininger Armin J 
Published: July 2018

SummaryTo determine the hydrodynamic parameters involved in thrombus formation on indwelling catheters, fibrin coagulation was investigated in an in vitro model and compared with the prevailing flow field. Computational analysis was used to simulate clot growth and identify the variables which determine its localization. The fibrin clot grew from the distal end of the catheter along the interface between the bulk stream and the annular vortex located immediately downstream of the catheter tip, finally filling the entire vortex. The calculations of flow parameters for three different growth stages showed that regions of clot formation always correlated with regions exhibiting the longest residence time. Fibrin clotting could be simulated by a mathematical model using residence time as the only variable parameter. Our results demonstrate that the residence time is the single most important flow factor for fibrin coagulation and thus probably for thrombus formation. When the residence time equals the clotting time for the fluid, thrombus formation is initiated. Conversely, it ceases when the area of long fluid residence times is replaced by a fibrin clot. Hence the fibrin clot represents a hydrodynamic optimization of the previously disturbed flow.
The Role of Fibrinolysis in the Pathogenesis of the Haemorrhagic Syndrome Produced by Virulent Isolates of African Swine Fever Virus
Authors: Villeda C J , Gómez-Villamandos J C , Williams S M , Hervás J , Wilkinson P J , Viñuela E 
Published: July 2018

SummaryThe activity of several proteins involved in fibrinolysis and the morphological changes in the blood vessel walls of pigs infected with highly virulent (Malawi’83) and moderately virulent (Dominican Republic ‘78-DR’78) ASF virus isolates were determined. Pigs infected with the Malawi’83 virus developed an increased fibrinolytic activity due to high plasma levels of tissue-plasminogen activator (t-PA) of 71.3 ± 22.8 IU/ml (mean ± SD), which correlated well with an increased activation of interstitial capillary endothelial cells and high levels of 1150 ± 73.6 nM of fibrin monomer in the circulation. Animals infected with DR’78 virus, in contrast, showed an inhibition of fibrinolysis in the late stages of disease with almost a 5-fold increase of plasminogen activator inhibitor (PAI) activity of 196.0 AU/ml. These results suggest that activation of the fibrinolytic system in pigs infected with the Malawi’83 virus is probably due to increased formation and deposition of fibrin in the circulation, contributing to an increased bleeding tendency and higher mortality. On the contrary, animals infected with DR’78 virus developed an inhibition of fibrinolysis and thus a reduction in bleeding.
Effects of Two Different Doses of Hirudin on APTT, Determined with Eight Different Reagents
Authors: Monreal Manuel , Monreal Luis , de Gopegui Rafael Ruiz , Espada Yvonne , Angles Ana Maria , Monasterio Jasone 
Published: July 2018

SummaryThe APTT has been considered the most suitable candidate to monitor the anticoagulant activity of hirudin. However, its use is hampered by problems of standardization, which make the results heavily dependent on the responsiveness of the reagent used. Our aim was to investigate if this different responsiveness of different reagents when added in vitro is to be confirmed in an ex vivo study.Two different doses of r-hirudin (CGP 39393), 0.3 mg/kg and 1 mg/kg, were administered subcutaneously to 20 New Zealand male rabbits, and the differences in prolongation of APTT 2 and 12 h later were compared, using 8 widely used commercial reagents. All groups exhibited a significant prolongation of APTT 2 h after sc administration of hirudin, both at low and high doses. But this prolongation persisted 12 h later only when the PTTa reagent (Boehringer Mannheim) was used. In general, hirudin prolonged the APTT most with the silica- based reagents.In a further study, we compared the same APTT reagents in an in vitro study in which normal pooled plasma was mixed with increasing amount of hirudin. We failed to confirm a higher sensitivity for silica- containing reagents. Thus, we conclude that subcutaneous administration of hirudin prolongs the APTT most with the silica-based reagents, but this effect is exclusive for the ex vivo model.
The Nijmegen Modification of the Bethesda Assay for Factor VIII:C Inhibitors: Improved Specificity and Reliability
Authors: Verbruggen Bert , Novakova Irena , Wessels Hans , Boezeman Jan , van den Berg Marijke , Mauser-Bunschoten Eveline 
Published: July 2018

SummaryAntibodies against factor VIII coagulant activity can appear in haemophiliacs who are treated with factor VIII preparations but also spontaneously in non-haemophiliacs. The Bethesda assay is the most commonly used method to detect these antibodies, but it lacks specificity especially in the lower range resulting in unreliable data.Two modifications are proposed and tested to resolve the imperfections:1. Buffering the normal plasma used in the assay- and control mixture with 0.1 M imidazole to pH 7.4.Replacing the imidazole buffer in the control mixture by immunodepleted factor VIII deficient plasma.These modifications allow better discrimination between positive and negative samples and improve reliability.
Limited Proteolysis of Human α-Thrombin by Urokinase Yields a Non-Clotting Enzyme
Authors: Bezeaud Annie , de Raucourt Emmanuelle , Miyata Toshiyuki , Bouton Marie-Christine , Angles-Cano Eduardo , Guillin Marie-Claude 
Published: July 2018

SummaryLimited proteolysis of human α-thrombin by various proteases has been efficiently used to demonstrate the importance of two insertion loops located on the surface of this molecule. In the present study, we demonstrate that two-chain urokinase (tcu-PA) specifically cleaves the B chain of α-thrombin giving rise to a transient derivative, consisting of two non-covalently linked subunits. Although the thrombin derivative conserves its activity towards the synthetic substrate S-2238 (Km = 8.4 μM and kcat = 145 s-1 versus respectively 4.5 μM and 149 s-1 for α-thrombin), most of its coagulant activity is lost (140 NIH u/mg versus 3000 NIH u/mg) and its ability to activate platelets is considerably reduced (threshold for full platelet aggregation 2.5 nM versus 0.25 nM). The thrombin fragments were separated by HPLC and after reduction and S-carboxyamidemethylation were digested with a lysylendopeptidase; the resulting peptides were separated by HPLC and sequenced. One fragment corresponded to B chain fragment 1-73 and the second to B chain fragment 74-259 covalently linked to the A chain, indicating that tcu-PA cleaves selectively the peptide bond Arg 73-Asn 74 in the B chain. The proteolytic derivative obtained, designated βu-thrombin, is therefore identical to the transient proteolytic derivative, αt-thrombin, produced by trypsin. Prolonged incubation with tcu-PA resulted in further conversion in a derivative analogous to γt-thrombin.These results show that the interactions of α-thrombin and u-PA are not limited to the inactivation of scu-PA by α-thrombin previously reported by other groups, but that reciprocally tcu-PA, the fully active form of scu-PA, may induce the loss of α-thrombin clotting and platelet stimulating activities. Furthermore, these data underscore the functional importance of the integrity of the peptide bond Arg 73-Asn 74 of the B chain on the recognition of macromolecular substrates by α-thrombin.
Protein Tyrosine Kinase Activation Is Required for LPS and PMA Induction of Tissue Factor mRNA in Human Blood Monocytes
Authors: Ternisien C , Ollivier V , Khechai F , Ramani M , Hakim J , de Prost D 
Published: July 2018

SummaryTissue factor (TF) is a transmembrane glycoprotein which assembles with factor VIIa on cell surfaces to form a proteolytically active cofactor-enzyme complex; the TF/VIIa complex initiates the coagulation protease cascade. In response to bacterial lipopolysaccharide (LPS) and phorbol-12 myristate 13-acetate (PMA), monocytes synthesize and express TF on their surface. However, the mechanisms by which LPS and PMA activate TF synthesis by human blood monocytes are not fully understood. As it has been established that LPS and PMA activate protein tyrosine kinase (PTK) in monocytes, we studied the role of PTK in LPS and PMA induction of TF by human blood monocytes. Both LPS-and PMA-induced TF activity was inhibited in a concentration-dependent manner by the protein tyrosine kinase-specific inhibitors herbimycin A and genistein. TF antigen determination confirmed that LPS- and PMA-induced cell surface TF protein levels decreased in parallel to TF functional activity under herbimycin A and genistein treatment. Northern blot analysis of total RNA from LPS- and PMA-stimulated monocytes showed a concentration-dependent decrease in TF mRNA levels in response to herbimycin A and genistein. The rate of decay of LPS-induced TF mRNA, evaluated after the arrest of transcription by actinomycin D was not affected by genistein and herbimycin A, suggesting that the inhibitory effects occur at least partly at the transcriptional level. We conclude that LPS- and PMA-induced TF production by human monocytes is dependent on tyrosine kinase activation.
Thrombotic Status Analyser
Authors: Gorog Diana A , Kovacs Iren B 
Published: July 2018

SummaryA physiologically relevant global in vitro test is described which allows the overall assessment of both thrombotic and thrombolytic activities of blood. In principle, native blood is drawn in pulses through a capillary tube where haemodynamic forces induce a platelet reaction culminating in vessel occlusion. Dislodgement/disintegration of the stabilised thrombus under pressure is a reflection of thrombolysis. Evidence is presented for the platelet-rich nature of the occlusion and that disruption of the thrombus and re-established patency is the result of thrombolysis, that is fibrinolysis with significant contribution from platelets.This test sensitively detects hypercoagulability (stasis); platelet hyperreactivity (coronary artery disease); anti-platelet effect (aspirin, prostacyclin) and the thrombolytic effect of, thrombin generation by, and resistance to streptokinase. Therefore, this overall assessment of thrombotic status could be of great diagnostic and therapeutic benefit in clinical practice.
A Structural/Functional Domain on Human CD36 Is Involved in the Binding of Anti-Nakα Antibodies
Authors: Daviet Laurent , Morel-Kopp Marie-Christine , Kaplan Cécile , McGregor John L 
Published: July 2018

SummaryThe human CD36 antigen is an integral membrane glycoprotein expressed by platelets, monocytes, endothelial cells and various tumor cell lines. CD36 acts as a receptor for thrombospondin, collagen, Plasmodium falciparum-infected erythrocytes and oxidized low- density lipoprotein. Individuals possessing the Naka-negative phenotype do not express CD36 and risk developing anti-CD36 isoantibodies upon blood transfusion or during pregnancy. In the present study, we have examined the interaction of an anti-Naka serum with recombinantly expressed CD36. Results obtained show that five functional CD36 monoclonal antibodies (OKM5, FA6-152, L103, ESIV-C7 and 10/5) prevent the binding of the anti-Naka serum whereas a single monoclonal antibody (13/10) has no effect. Consistent with this result, an epitope map of CD36 generated using cross-blocking experiments, indicates that the inhibitory monoclonal antibodies recognize closely- related epitopes whereas 13/10 reacts with a distinct CD36 determinant. Furthermore, we have demonstrated, in a recent study, that OKM5, FA6-152, L103 and 10/5 bind to the same CD36 domain defined by amino acids 155 to 183. Taken together, our results indicate that the 155-183 sequence is important for the binding of the anti-Naka serum to CD36 and may represent a surface-exposed, immunogenic and presumably functional region on human CD36.
Differences in the Interactions of Lupus Anticoagulant IgG with Human Prothrombin and Bovine Prothrombin
Authors: Mohan Rao L Vijaya , Hoang An D , Rapaport Samuel I 
Published: July 2018

SummaryLupus anticoagulant (LA) IgGs have been reported to inhibit more effectively and consistently the Xa/Va/phospholipid complex-catalyzed activation of human prothrombin than the Xa/Va/phospholipid complex-catalyzed activation of bovine prothrombin. This led us to carry out studies to determine whether the ability to inhibit the activation of prothrombin of LA IgGs, separated from the plasma of 15 patients by protein A affinity chromatography, could be related to the ability of the LA IgGs to bind to prothrombin under various experimental conditions. Of 14 LA IgG preparations tested all prolonged to a variable but substantial extent the dilute Russell’s viper venom time (dRVVT) of human plasma but only minimally prolonged the dRVVT of bovine plasma. In a purified prothrombin activation system with a rate limiting concentration of phospholipid, all 15 LA IgG preparations inhibited the activation of human prothrombin with the majority showing >50% of inhibition. In contrast, only one LA IgG markedly inhibited (>50%) the activation of bovine prothrombin and five others moderately inhibited (25-40%) the activation of bovine prothrombin. Nevertheless, the majority of LA IgG preparations bound to immobilized bovine prothrombin on a Western blot and also to immobilized bovine prothrombin on a microtiter well. In an ELISA in which phosphatidylserine (PS) was immobilized on microtiter wells, bovine prothrombin supported the binding of 10 of 15 LA IgG preparations to PS. However, the extent of binding was lower than that observed with human prothrombin. In experiments with 125I-human prothrombin or 125I-bovine prothrombin in a solution containing Ca2+, the addition of PS/PC vesicles enhanced the binding of both human and bovine prothrombin to some LA IgG preparations. The enhanced binding was particularly evident for bovine prothrombin. Although seemingly related for some preparations, the ability of a LA IgG to bind to bovine prothrombin, either in the presence or absence of PS, and the ability of that LA IgG to inhibit the activation of bovine prothrombin was not consistently related for all preparations.
The Thrombin Activation Pathway Modulates the Assembly, Structure and Lysis of Human Plasma Clots In Vitro
Authors: Torbet Jim 
Published: July 2018

SummaryThrombin activation of the soluble plasma protein fibrinogen is vital for successful haemostasis. Thrombin is generated from prothrombin by the prothrombinase complex which also includes factor Xa, factor Va, Ca2+ and a procoagulant membrane surface. Factor X activation is catalysed in a complex including either factor Vila and tissue factor, or factor IXa and factor Villa. Factor IXa can be generated either by the factor Vlla/tissue factor complex or by factor XIa which is in turn produced by the contact phase reactions in vitro. Once activated, fibrinogen develops into the fibrin polymeric matrix at the site of injury. It is not known to what extent the properties of this haemostatic plug are sensitive to the pathway leading up to thrombin generation. Here static human plasma is studied in vitro using magnetically induced birefringence. It is shown that the contact phase/factor XIa pathway gives rise to linear fibrin assembly progress curves whereas the factor Vlla/tissue factor activation of factor X provokes largely sigmoid assembly. The latter pathway also causes the formation of significantly thicker fibres even although assembly is more rapid. This result is the inverse of that anticipated from the study of simple model systems. Whilst the streptokinase activated lysis of both types of clot exhibits similar biphasic kinetics, an exponential main phase followed by a sigmoidal tailing off, the data suggest that clots produced by the contact phase/factor XIa pathway are more recalcitrant to lysis. These results demonstrate that the profile of thrombin generation not only determines the kinetics of assembly but also influences the rate of lysis and structure of the haemostatic plug.
Soluble Thrombomodulin Purified from Human Urine Exhibits a Potent Anticoagulant Effect In Vitro and In Vivo
Authors: Takahashi Yasuo , Hosaka Yoshitaka , Niina Hiromi , Nagasawa Katsuaki , Naotsuka Masaaki , Sakai Kiyoshi , Uemura Akio 
Published: July 2018

SummaryWe examined the anticoagulant activity of two major molecules of soluble thrombomodulin purified from human urine. The apparent molecular weights of these urinary thrombomodulins (UTMs) were 72,000 and 79,000, respectively. Both UTMs showed more potent cofactor activity for protein C activation [specific activity >5,000 thrombomodulin units (TMU)/mg] than human placental thrombomodulin (2,180 TMU/mg) and rabbit lung thrombomodulin (1,980 TMU/mg). The UTMs prolonged thrombin-induced fibrinogen clotting time (>1 TMU/ml), APTT (>5 TMU/ml), TT (>5 TMU/ml) and PT (>40 TMU/ml) in a dose-dependent fashion. These effects appeared in the concentration range of soluble thrombomodulins present in human plasma and urine. In the rat DIC model induced by thromboplastin, administration of UTMs by infusion (300-3,000 TMU/kg) restored the hematological abnormalities derived from DIC in a dose-dependent fashion. These results demonstrate that UTMs exhibit potent anticoagulant and antithrombotic activities, and could play a physiologically important role in microcirculation.
Regulation of Platelet Aggregation by Post-fibrinogen Binding Events
Authors: Peerschke Ellinor I 
Published: July 2018

SummaryA variety of data suggest that fibrinogen binding is necessary but not sufficient for platelet aggregation: post fibrinogen binding events may play an important role. The present study compared fibrinogen binding and platelet aggregation in response to dithiothreitol (DTT) and ADP. DTT induced saturable and specific fibrinogen binding (Kd 0.07 + 0.02 μM, Bmax 15,000 + 3000 molecules/platelet) which supported complete platelet aggregation as determined by single platelet counting. The aggregates were small, however, and more readily dissociated by EDTA than their ADP-treated counterparts, despite quantitatively similar fibrinogen binding. Unlike fibrinogen bound to ADP-stimulated platelets, fibrinogen bound to DTT-treated platelets remained sensitive to dissociation by EDTA over a 3 h time course, retained its ability to support aggregation, even when aggregation was induced 60 min after the initial platelet exposure to fibrinogen, and remained accessible to polyclonal antibodies and plasmin. Confocal scanning laser microscopy showed only surface clustering of fibrinogen bound to DTT-treated platelets over the 3 h time course compared to rapid fibrinogen clearing from the surface of ADP-stimulated platelets. These data suggest that post fibrinogen binding events involved in the stabilization of fibrinogen binding and/or the redistribution of bound fibrinogen may play important roles in regulating platelet aggregation.
Vessel Wall Injury and Arterial Thrombosis Induced by a Photochemical Reaction
Authors: Saniabadi Abby R , Umemura Kazuo , Matsumoto Nobuteru , Sakuma Sadayuki , Nakashima Mitsuyoshi 
Published: July 2018

SummaryArterial thrombosis may be initiated in an experimental animal by a photochemical reaction between transmural green light and i.v. administered Rose Bengal, a photosensitizer dye. In this study, scanning electron microscopy has been used to reveal the nature of vessel injury and the cellular composition of the photochemically induced thrombus. A 5 mm segment of the guinea pig femoral artery was occluded by a thrombus about 10 min after irradiation with green light in the presence of systemically administered Rose Bengal. Electron microscopy revealed that following photochemical reaction, endothelial cells first contract and, with further irradiation, become detached from the vessel wall, with their cell membrane being destroyed at the irradiated site where an occlusive platelet-rich thrombus was formed. Endothelial cell injury and vessel occlusion could be completely inhibited by the aminothiol, DL-cysteine administered i.v. 1 min after Rose Bengal. The mechanism of endothelial injury in this model appears to be by singlet molecular oxygen, 1O2 formed by energy transfer from the photo-excited dye to O2.
Surgery of a Posterior Communicating Artery Aneurysm with Fetal-Type Circulation
Authors: González Nicolás , Morales Manuel , Ravera Franco , Ruiz-aburto Arturo , Vásquez Juan , Muller José , Mosquera Jhon , Zapata Rodrigo 
Published: July 2018

AbstractInadvertent occlusion of a fetal-type posterior communicating artery in aneurysm surgery could result in posterior circulation infarction and neurological morbidity. The case of a patient with an unruptured posterior communicating artery aneurysm with lateral projection and a fetal-type posterior communicating artery is presented. The utility of the carotid-oculomotor window as a surgical corridor to safely find the fetal-type posterior communicating artery is discussed.