bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Levels of Circulating Thrombomodulin in Human Foetuses and Children
Authors: Aurousseau Marie-Hélène , Gozin Danielle , Daffos Fernand , D’Angelo Armando , Forestier François , Boffa Marie-Claire , Menashi Suzanne 
Published: March 2018

SummaryThrombomodulin (TM) is an endothelial cell surface proteoglycan with anticoagulant functions, also implicated in cell proliferation, cell-cell adhesion and differentiation. In this study we determined circulating plasma TM (pTM) levels in human foetuses at different stages of pregnancy, at birth and in childhood. TM levels increased with gestational age, the median level reaching a peak of approximately 165 ng/ml between the 23rd and 26th week, thereafter decreasing gradually, reaching a value of 108 ng/ml at birth. pTM continues to decrease progressively during childhood, reaching in the 5-15 years group a median of 56 ng/ml which approaches the adult value. The pTM peak was statistically significant and represents a specific foetal phenomenon as it was independent of the corresponding maternal values. As a whole, the pTM pattern during foetal maturation appears totally different from that of protein C, prothrombin and other coagulation activators and inhibitors and thus, TM may play in the foetus another role in addition to its well-known anticoagulant function.
Correction for Lack of Coincidence of Normal and Abnormal Calibration Slopes in ISI Determination
Authors: Besselaar A. M. H. P. , Jespersen J. , Tripodi A. , Houghton D. , Poller L. 
Published: March 2018

SummaryAn underlying assumption of the WHO orthogonal regression model for prothrombin time standardisation is that a single line describes the relationship between PT of abnormal and normal plasmas. The aim was to evaluate Tomenson’s correction for lack of coincidence using the model of the ECAA human reagent with lyophilized plasma calibrations. Local ISI calibrations using ECAA lyophilized normal and abnormal plasmas were performed on coagulometers with the ECAA human thromboplastin. They gave a high incidence of non-linearity of the two calibration slopes. The mean percentage deviation from assigned values of the target coumarin plasmas coagulometer INR at 45 centres before local ISI correction was 16.6% and 11.9% respectively in two studies. After local ISI calibration, the unsigned deviation was reduced to 5.54% and 6.61% respectively. Tomenson’s correction for non-linearity further reduced the mean deviation to 3.08% and 2.96 % respectively in the two studies demonstrating the value of the procedure.
Endogenous Nitric Oxide Acts as a Natural Antithrombotic Agent In Vivo by Inhibiting Platelet Aggregation in the Pulmonary Vasculature
Authors: Emerson Michael , Momi Stefania , Paul William , Francesco Paolo , Page Clive , Gresele Paolo 
Published: March 2018

SummaryNitric oxide (NO) is a powerful vasodilator and an inhibitor of platelet aggregation in vitro. While the ability of NO to modulate vascular tone in vivo has been proven, only a few studies have assessed its platelet inhibitory activity in vivo.We have employed two complementary animal models of pulmonary platelet thromboembolism to assess the antithrombotic activity of endogenous NO in vivo.
The inhibition of nitric oxide synthase (NOS) by L-NAME significantly potentiated while the administration of the NOS substrate L-arginine significantly reduced the accumulation of 111In-labelled platelets in the pulmonary vasculature of rabbits induced by intravenous collagen plus epinephrine. L-NAME or L-arginine did not, however, modify 111In-labelled erythrocyte distribution in lungs and phenylephrine had no effect on platelet accumulation following collagen + adrenaline, suggesting that the effects of L-NAME were not due to vasoconstriction but rather to a direct modification of platelet function. In mice, L-NAME significantly reduced the dose of collagen + adrenaline required to induce thromboembolic mortality, increased the fall in circulating platelets and increased the % of pulmonary vessels occluded by platelet thrombi. The effects of L-NAME were reversed by L-arginine but not by a dose of nicardipine exerting maximal vasodilatation. Phenylephrine did not potentiate collagen + adrenaline-induced mortality.In the pulmonary vasculature in vivo, endogenous NO inhibits collagen + adrenaline-induced aggregation and enhances platelet disaggregation. This natural modulator function of NO is exerted via a direct effect on platelets and not as a result of haemodynamic changes.
Thrombin Receptor Occupancy Modulates Aggregation Efficiency and Platelet Surface Expression of vWF and Thrombospondin at Low Thrombin Concentrations
Authors: Legrand Chantal , Kasirer-Friede Ana , Frojmovic Mony 
Published: March 2018

SummaryPrevious studies evaluating requirements for occupancy of thrombin receptors in normal platelet secretion and aggregation, using the thrombin antagonists hirudin and PPACK (D-Phe-Pro-Arg-chloromethylke-tone), have suggested that at low thrombin activating concentrations (0.025–0.13 U/ml), occupancy was required only in the first 45–60 s following activation. In our study, we differentiate between thrombin receptor occupancy requirements for surface expression of secreted adhesive proteins, for activation of GPIIb-IIIa receptors, and for aggregation of washed platelets (WP) in laminar shear flow. Platelets activated with 0.05 U/ml thrombin for 10 min to allow maximal secretion (hereafter referred to as “pre-activated platelets”), then sheared, showed a 50–70% decrease in platelet counts after 60 s of shear. Treatment of pre-activated platelets with hirudin or PPACK produced a 65% reduction of capture efficiencies, αG (reflecting experimental/theoretical initial rates of aggregation), as well as a 30–40% decrease in the surface expression of von Willebrand factor (vWF) and thrombospondin (TSP). However, α-granule membrane P-selectin expression and numbers of activated GPIIb-IIIa receptors were comparable for treated and non-treated platelets. No significant difference in any of the parameters tested was observed when platelets were similarly pre-activated with 0.2 U/ml thrombin, due to treatment with thrombin antagonists. Binding of soluble FITC-vWF (GRGDSP-sensitive) to pre-activated, thrombin antagonist treated platelets, was greatly reduced (≥80%). Soluble Fg was shown to bind to antagonist-treated pre-activated platelets, but could not significantly enhance platelet aggregation. Although occupancy of thrombin receptors by catalytically active thrombin is required transiently for secretion and activation of platelets, there is a further requirement for thrombin occupancy at low thrombin concentrations, for optimizing initial rates of platelet aggregation, surface expression of vWF and TSP, and activated GPIIb-IIIa ligand recognition.
Recombinant vWF Type 2A Mutants R834Q and R834W Show a Defect in Mediating Platelet Adhesion to Collagen, Independent of Enhanced Sensitivity to a Plasma Protease
Authors: Lankhof Hanneke , Damas Conchi , Schiphorst Marion , IJsseldijk Martin , Bracke Madelon , Furlan Miha , de Groot Philip , Vink Tom , Sixma Jan 
Published: March 2018

SummaryType 2A von Willebrand Disease (vWD) is characterized by the absence of high molecular weight von Willebrand factor (vWF) multimers in plasma which is caused by enhanced extracellular proteolysis or defective intracellular transport. We identified in vWD type 2A patients two mutations in the A2 domain at position 834 in which arginine (R) was substituted for glutamine (R834Q) or tryptophan (R834W). We reproduced these mutations in vWF cDNA and expressed the recombinant proteins in furin cDNA containing baby hamster kidney (fur-BHK) cells. The subunit composition and the multimeric structure of both mutants was similar to wild-type (WT) vWF. Characterization of mutant R834Q by ristocetin or botrocetin induced platelet binding, and by binding to heparin showed no abnormality. R834W had normal botrocetin induced platelet binding, but ristocetin induced platelet binding and binding to heparin were decreased. Under static conditions R834Q and R834W, at 10 μg/ml, bound equally well to collagen type III as WT-vWF. At high shear rate conditions both mutants supported platelet adhesion normally when coated to a glass surface or preincubated on collagen. When R834Q or R834W was added to the perfusate, adhesion to collagen type III was 50% of the WT-vWF value, which was not due to a decreased collagen binding under flow. A divalent cation dependent protease, purified from plasma, degraded the 2A mutants rapidly while WT-vWF was not affected. In conclusion, the mutations present in the A2 domain of vWF result in an enhanced proteolytic sensitivity to a divalent ion-dependent protease. When present in the perfusate, R834Q and R834W show a decrease in platelet adhesion to collagen type III under flow conditions, which is not caused by decreased binding of the mutant vWF to collagen or enhanced proteolysis.
Stimulation of Proteinase Activated Receptor-2 Causes Endothelial Cells to Promote Blood Coagulation In Vitro
Authors: Norström Eva , Sundelin Johan , Nystedt Sverker , Alm Anna-Karin 
Published: March 2018

SummaryProteolytically activated receptors define a new subclass among the G-protein coupled receptors. Proteinase activated receptor-2 (PAR-2), the second member to be identified of this growing receptor subclass, can be activated by trypsin and trypsin-like serine proteases such as mast cell tryptase. PAR-2 is expressed in endothelial cells. Here we have studied if activation of PAR-2 changes the coagulation properties of cultured human umbilical vein endothelial cells. We show that activation of PAR-2 induces rapid and transient formation of tissue factor mRNA with a maximum level 1 hour after receptor stimulation. The increased mRNA level was accompanied by an increased tissue factor activity at the endothelial cell surface, shortening coagulation time in a standard clotting assay. The level of tissue factor activity after PAR-2 activation was comparable with the effects of thrombin receptor (PAR-1) activation although neither of the two protease receptors were as strong inducers of tissue factor as tumor necrosis factor-α.
Geographic Distribution of the 20210 G to A Prothrombin Variant
Authors: Doggen C. J. M. , Zivelin A. , Arruda V. R. , Aiach M. , Siscovick D. S. , Hillarp A. , Watzke H. H. , Bernardi F. , Cumming A. M. , Preston F. E. , Reitsma P. H. , Rosendaal F. R. 
Published: March 2018

SummaryA variant in prothrombin (clotting factor II), a G to A transition at nucleotide position 20210, has recently been shown to be associated with the prothrombin plasma levels and the risk of both venous and arterial thrombosis. The purpose of this study was to investigate the prevalence of carriership of this mutation in various populations.We combined data from 11 centres in nine countries, where tests for this mutation had been performed in groups representing the general population. We calculated an overall prevalence estimate, by a precision-weighted method, and, since the distribution of the prevalences did not appear homogeneous, by an unweighted average of the prevalences. We examined differences in the prevalences by geographical location and ethnic background as a possible explanation for the heterogeneity.Among a total of 5527 individuals who had been tested, 111 heterozygous carriers of the 20210A mutation were found. The prevalence estimates varied from 0.7 to 4.0 between the centres. The overall prevalence estimate was 2.0 percent (CI95 1.4-2.6%). The variation around the summary estimate appeared more than was expected by chance alone, and this heterogeneity could be explained by geographic differences. In southern Europe, the prevalence was 3.0 percent (CI95 2.3 to 3.7%), nearly twice as high as the prevalence in northern Europe (1.7%, CI95 1.3 to 2.2%). The prothrombin variant appeared very rare in individuals from Asian and African descent.The 20210A prothrombin variant is a common abnormality, with a prevalence of carriership between one and four percent. It is more common in southern than in northern Europe. Since this distribution within Europe is very different to that of another prothrombotic mutation (factor V Leiden or factor V R506Q), founder effects are the most likely explanation for the geographical distribution of both mutations.
Anti-hepatitis G E2 Antibody Detection and Its Relation to Serum HGV-RNA in Patients with Clotting Disorders: High Prevalence of HGV Infection and Spontaneous Remission
Authors: Sheng L. , Soumillion A. , Peerlinck K. , Verslype C. , Schelstraete R. , Gyselinck F. , Emonds M.-P. , Hess G. , Vermylen J. , Desmyter J. , Yap S. H. 
Published: March 2018

SummaryIn a previous study, we have determined the prevalence of serum HGV-RNA in patients with congenital clotting disorders. Twenty-six (15%) of 175 patients investigated were serum HGV-RNA positive. In addition, HGV-RNA was detectable in peripheral blood mononuclear cells (PBMC) in ten percent of the cases, three of these patients were serum HGV-RNA negative.In the present study, we have determined the prevalence of anti-HGV-E2 antibodies in the same patient population. Anti-HGV-E2 as determined by ELISA was detected in 45 patients (25.7%). Forty of these patients were serum HGV-RNA negative.Ninety-two percent of the 26 HGV viremic patients and all but one patient (44 patients) with detectable anti-HGV-E2 had coinfection with the hepatitis C virus (HCV). Of these coinfected patients, 62.5% of HGV viremic patients and 53% of anti-HGV-E2 positive patients showed elevated serum ALT levels. Anti-HGV-E2 seroconversion is thus not associated with HCV infection. Two patients who were solely infected with HGV had normal serum ALT levels. In a retrospective longitudinal study, we have observed in 15 patients that serum HGV-RNA persisted during one to 19 years of follow-up, while anti-HGV-E2 was repeatedly negative. Five additional patients who were anti-HGV-E2 positive with concomitant detectable HGV-RNA (4 patients in serum and 1 patient in PBMC) became HGV-RNA negative during follow-up, ranging from 1 to 8 years after the first detection of anti-HGV-E2 antibodies. Two patients had lost anti-HGV-E2 antibodies 3 to 6 years after the seroconversion without the re-appearance of serum HGV-RNA. From these findings, it is clear that the prevalence rate of HGV infection in patients with clotting disorders as determined by PCR assay for HGV-RNA and anti-HGV-E2 by ELISA is actually higher than the prevalence of HGV viremia. Although HGV viremia may persist for longer than 19 years, most of the patients infected with HGV may clear the viremia spontaneously. The clearance of viremia is usually associated with seroconversion to anti-HGVE2. In addition, anti-HGV-E2 may be lost during years of follow-up without the reappearance of the HGV-RNA. Although HGV infection does not seem to influence the fate of HCV infection and does not induce increased levels of serum ALT, the clinical significance of long-term infection remains to be established.
Homozygous Protein C Deficiency: Description of a New Mutation and Successful Treatment with Low Molecular Weight Heparin
Authors: Monagle Paul , Andrew Maureen , Halton Jacqueline , Marlar Richard , Jardine Lawrence , Vegh Patricia , Johnston Marilyn , Webber Colin , Massicotte Patricia 
Published: March 2018

SummaryWe present a kindred with a new mutation of the protein C gene, in which the proband had an unusual clinical presentation. The relationship between warfarin induced skin necrosis and level of anticoagulation was investigated. The pharmacokinetics of protein C concentrate was assessed to determine frequency of replacement therapy. The clinical and biochemical efficacy of therapy with low molecular weight heparin (LMWH) was assessed. The effect of long-term LMWH on bone density in the growing child was monitored using whole body densitometry.Warfarin therapy required an INR of greater than 3.5 to avoid skin necrosis. If protein C replacement was to be used, doses of 100 U/kg/day would have been required to maintain protein C levels consistently at or above 0.20 U/ml. While receiving prophylactic therapy with LMWH for almost 3 years, there were no episodes of recurrent thrombosis, no skin necrosis and no bleeding. Biochemical markers of in vivo thrombin generation were suppressed and within the normal range. Bone density continued to increase at the normal rate throughout the treatment period.LMWH is an effective form of long-term therapy for homozygous protein C deficient patients with measurable protein C levels.
Fibrinogen Coating Density Affects the Conformation of Immobilized Fibrinogen: Implications for Platelet Adhesion and Spreading
Authors: Moskowitz Keith , Kudryk Bohdan , Coller Barry 
Published: March 2018

SummaryAdhesion of platelets to immobilized fibrinogen appears to play an important role in a variety of physiologic and pathologic phenomena. We previously observed that the fibrinogen concentration used to coat polystyrene wells affected the morphology and distribution of GP IIb/ IIIa receptors on the surface of platelets adherent to the fibrinogen. One possible explanation for these differences is that fibrinogen immobilized at high density adopts a different conformation than fibrinogen immobilized at low density. To address this possibility, we studied the binding of a panel of anti-fibrinogen monoclonal antibodies (mAbs) to fibrinogen immobilized at different coating densities. Three different patterns of binding were observed: 1) a linear increase in binding to wells coated with 1-10 μg/ml fibrinogen, followed by a lesser increase or plateau at higher fibrinogen concentrations (mAbs Fd4-4E1, Fd4-7B3, 1D4, 4-2); 2) minimal reactivity at all fibrinogen concentrations (mAbs GC4-1A12, 2C34); 3) a biphasic response, with a linear increase up to 10 μg/ml fibrinogen and then a significant decline in binding at higher fibrinogen concentrations (mAbs 311, 31A9, FPA 19/7, 9C3, 1C5-A5/2, 44-3). The patterns of mAb binding to fibrinogen immobilized from plasma were similar. Most mAbs that demonstrated a biphasic response bound poorly or not at all to soluble fibrinogen, while mAbs that demonstrated a linear/plateau response were able to bind soluble fibrinogen. At equal surface densities, mAbs that bound biphasically, particularly mAb 1C5-A5/2, were more reactive to urea-denatured than native fibrinogen. mAbs 1C5-A5/2 and 44-3 are specific for γ 1-78 and 95-265, respectively, suggesting that the fibrinogen γ-chain may be sensitive to changes in conformation induced by immobilization. In summary, these data suggest that fibrinogen immobilized at 1-10 μg/ml adopts a conformation unlike soluble fibrinogen, while fibrinogen immobilized at >30 μg/ml adopts a more solution-like conformation. These differences in fibrinogen conformation may partially account for the ability of platelets to bind to immobilized fibrinogen without the addition of agonist, as well as the differences in spreading and GPIIb/IIIa distribution on platelets adherent to high- versus low-density immobilized fibrinogen.
Adenosine 3’:5’-Cyclic Monophosphate Induces Regulated Secretion of Tissue-Type Plasminogen Activator and von Willebrand Factor from Cultured Human Endothelial Cells
Authors: Hegeman R. J. , Eijnden-Schrauwen van den , Emeis J. J. 
Published: March 2018

SummaryThe effect of compounds increasing intracellular adenosine 3’:5’-cyclic monophosphate [cAMP]i levels (prostacyclin, isoproterenol, forskolin, cholera toxin), and of the cAMP analogs 8-bromo-cAMP and dibutyryl-cAMP, on the regulated secretion (acute release) of tissue-type plasminogen activator (tPA) and von Willebrand factor (vWF) was studied in cultured human umbilical vein endothelial cells (HUVEC).Prostacyclin, isoproterenol and forskolin, which increased [cAMP]i in HUVEC, and the cell-permeant cAMP analog 8-bromo-cAMP induced dose- and time-dependent secretion of tPA and vWF. The extent of vWF and tPA release correlated with [cAMP]i, and was increased by the phosphodiesterase inhibitor isobutylmethylxanthine.In contrast to thrombin, the cAMP-elevating agents did not increase the intracellular calcium concentration [Ca2+]i in HUVEC. At sub-maximal concentrations, the effects of thrombin and prostacyclin were additive.Our results show that an increase in [cAMP]i resulted in regulated secretion (acute release) of tPA and vWF from HUVEC, without the concomitant increase in [Ca2+]i which is, in HUVEC, essential for thrombin-induced regulated secretion to occur. cAMP-induced secretion represents a novel mechanism for causing regulated secretion of tPA and vWF from endothelial cells.
A Founder Effect Is Proposed for Factor XIII B Subunit Deficiency Caused by the Insertion of Triplet AAC in Exon III Encoding the Second Sushi Domain
Authors: Souri Masayoshi , Izumi Tomonori , Higashi Yoichiro , Girolami Antonio , Ichinose Akitada 
Published: March 2018

SummaryWe previously concluded that genetic defects in the B subunit of factor XIII were the basis for former Type I deficiency (i.e. factor XIII B subunit deficiency). When we examined an Italian patient with the disease at the DNA level, restriction digestion and sequencing analyses of amplified DNAs revealed that the proband and her family members possessed an AAC insertion within the codon for Tyr-80 in exon III in the gene for the B subunit, a nucleotide polymorphism (A-G) in its 3’-noncoding region in exon XII, and a short tandem repeat polymorphism of (TTTA)9 in the 3’-flanking region. These mutations and 3’-polymorphisms were also identified in another Italian family reported in a previous study (10), suggesting that a founder effect is responsible for factor XIII B subunit deficiency in Italians.
Coagulation Factor V (Arg506 → Gln) Mutation and Early Saphenous Vein Graft Occlusion after Coronary Artery Bypass Grafting
Authors: Silveira Angela , Ferdinand van’t Hooft , Tornvall Per , Blombäck Margareta , Wiman Björn , Rydén Lars , Hamsten Anders , Moor Elisabeth 
Published: March 2018

SummaryThe factor V (Arg506→Gln) mutation confers an increased risk of deep vein thrombosis, whereas its role in saphenous vein graft closure after coronary artery bypass grafting (CABG) remains unclear. This study examined the anticoagulant response to activated protein C (APC ratio) in relation to the surgical trauma and the significance of the factor V Leiden mutation in determining postoperative thrombin generation and fibrin formation and the risk of early vein graft occlusion. A total of 108 men undergoing elective CABG for exertional angina pectoris (mean age 61.1 ± 8.7 years) were examined. The patency of saphenous vein grafts was studied at routine reangiography three months after CABG.Of 100 patients who underwent reangiography, 23 had one or more occluded vein grafts at reangiography. Heterozygosity for the factor V (Arg506→Gln) mutation tended to be associated with early saphenous vein graft occlusion (5/11 carriers vs. 18/89 non-carriers with graft occlusion, व2 = 3.52, p = 0.06), whereas pre- and postoperative APC ratios did not. Pre- and postoperative determinations of prothrombin fragment 1+2, thrombin-antithrombin complexes and soluble fibrin levels did not differ between patients with and without the mutation.Early saphenous vein graft occlusion after CABG could tentatively be added to deep vein thrombosis as a vascular complication that can be attributed to the factor V (Arg506→Gln) mutation.