bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased Thromboxane Biosynthesis in Essential Thrombocythemia
Authors: Rocca Bianca , Ciabattoni Giovanni , Tartaglione Raffaele , Cortelazzo Sergio , Barbui Tiziano , Patrono Carlo , Landolfi Raffaele 
Published: July 2018

SummaryIn order to investigate the in vivo thromboxane (TX) biosynthesis in essential thromboeythemia (ET), we measured the urinary exeretion of the major enzymatic metabolites of TXB2, 11-dehydro-TXB2 and 2,3-dinor-TXB2 in 40 ET patients as well as in 26 gender- and age-matched controls. Urinary 11-dehydro-TXB2 was significantly higher (p <0.001) in thrombocythemic patients (4,063 ± 3,408 pg/mg creatinine; mean ± SD) than in controls (504 ± 267 pg/mg creatinine), with 34 patients (85%) having 11-dehydro-TXB2 >2 SD above the control mean. Patients with platelet number <1,000 × 109/1 (n = 25) had significantly higher (p <0.05) 11 -dehydro-TXB2 excretion than patients with higher platelet count (4,765 ± 3,870 pg/mg creatinine, n = 25, versus 2,279 ± 1,874 pg/mg creatinine, n = 15). Average excretion values of patients aging >55 was significantly higher than in the younger group (4,784 ± 3,948 pg/mg creatinine, n = 24, versus 2,405 ± 1,885 pg/mg creatinine, n = 16, p <0.05). Low-dose aspirin (50 mg/d for 7 days) largely suppressed 11-dehydro-TXB2 excretion in 7 thrombocythemic patients, thus suggesting that platelets were the main source of enhanced TXA2 biosynthesis. The platelet count-corrected 11-dehydro-TXB2 excretion was positively correlated with age (r = 0.325, n = 40, p <0.05) and inversely correlated with platelet count (r = -0.381, n = 40, p <0.05). In addition 11 out of 13 (85%) patients having increased count-corrected 11-dehydro-TXB2 excretion, belonged to the subgroup with age >55 and platelet count <1,000 × 1099/1. We conclude that in essential thrombocythemia: 1) enhanced 11-dehydro-TXB2 excretion largely reflects platelet activation in vivo;2) age as well as platelet count appear to influence the determinants of platelet activation in this setting, and can help in assessing the thrombotic risk and therapeutic strategy in individual patients.
Plasma Levels of Protein S, Protein C, and Factor X: Effects of Sex, Hormonal State and Age
Authors: Henkens C M A , Bom V J J , Schaaf W van der , Pelsma P M , Sibinga C Th Smit , Kam P J de , Meer J van der 
Published: July 2018

SummaryWe measured total and free protein S (PS), protein C (PC) and factor X (FX) in 393 healthy blood donors to assess differences in relation to sex, hormonal state and age. All measured proteins were lower in women as compared to men, as were levels in premenopausal women as compared to postmenopausal women. Multiple regression analysis showed that both age and subgroup (men, pre- and postmenopausal women) were of significance for the levels of total and free PS and PC, the subgroup effect being caused by the differences between the premenopausal women and the other groups. This indicates a role of sex-hormones, most likely estrogens, in the regulation of levels of pro- and anticoagulant factors under physiologic conditions. These differences should be taken into account in daily clinical practice and may necessitate different normal ranges for men, pre- and postmenopausal women.
Venous Antithrombotic and Anticoagulant Activities of a Fucoïdan Fraction
Authors: Mauray Sandrine , Sternberg Claude , Theveniaux Jocelyne , Millet Jean , Sinquin Corinne , Tapon-Bretaudiére Jacqueline , Fischer Anne-Marie 
Published: July 2018

SummaryFucoïdans catalyse thrombin inhibition by antithrombin (AT) and heparin cofactor II (HCII); their affinity for each serpin varies according to the seaweed species from which they are extracted, as well as their chemical composition and molecular weight. We extracted a homogeneous fucoïdan fraction from Ascophyllum nodosum, a brown seaweed, and tested its anticoagulant and antithrombotic activities. At a fucoïdan concentration of 3.75 µg/ml, thrombin inhibition mediated by AT showed an apparent second-order rate constant (kapp) of 2 × 108 M-1 min-1, compared to 1.5 × 106 M-1 min-1 for the uncatalyzed reaction. The kapp value of thrombin inhibition via HCII was 1.17 × 109 M-1 min-1 at a fucoïdan concentration of 50 µg/ml, compared to 1.72 × 105 M-1 min-1 for the uncatalyzed reaction. In a Wessler model of venous thrombosis, the fucoïdan fraction, injected intravenously to rabbits 10 min before thrombosis induction, exhibited antithrombotic activity: 1.8 mg/kg was the dose which inhibited F Xa-induced thrombus formation by 80% (ED80), compared to a heparin ED80 of 0.1 mg/kg. At this ED80 the antithrombotic effect of the fucoïdan persisted longer than that of heparin (30 min versus 15 min). The thrombin clotting time (TCT) was significantly prolonged (73 s versus control 29 s, compared to 53 s with heparin) 10 min after a fucoïdan bolus infusion giving a plasma fucoïdan concentration of 14.6 ± 2.7 µg/ml. The bleeding time was slightly increased after fucoïdan infusion at the ED80. Fucoïdan extracted from marine flora thus shows promise as an antithrombotic drug.
Individual Variations in the Fibrinolytic Response During and After Cardiopulmonary Bypass
Authors: Chandler W L , Fitch J C K , Wall M H , Verrier E D , Cochran R P , Soltow L O , Spiess B D 
Published: July 2018

SummaryThe purpose of this study was to determine whether individual patients show different patterns of fibrinolytic response to cardiopulmonary bypass (CPB) and whether preoperative or intraoperative parameters were predictive of these different patterns. Active t-PA, active PAI-1 and total t-PA antigen were measured in plasma samples obtained from 38 subjects, age 32 to 85 (median 69 years), before, during and after CPB. Four patterns of fibrinolytic response were noted: 1) 40% of patients showed the “typical” response, a rapid rise in active and total t-PA during CPB followed postoperatively by elevated PAI-I and reduced t-PA, 2) 10% showed no change in t-PA or PAI-1 during or after CPB, 3) 24% showed no change in t-PA with an increase in PAI-1 postoperatively, and 4) 26% showed an increase in t-PA during CPB with no change in PAI-1 postoperatively. When present, the t-PA response was rapid, occurring within the first 30 min of CPB and was more common in patients undergoing valve surgery than in coronary artery bypass grafting (p <0.005). Increased levels of PAI-1 postoperatively were associated with ischemic times greater than 70 min (p = 0.003) but not with the total length of CPB. Age, sex, CPB temperature, total CPB time and preoperative levels of t-PA and PAI-1 were not associated in the intra- or postoperative fibrinolytic response pattern. We conclude that the fibrinolytic response to CPB is heterogeneous. Further studies will be needed to determine whether different response patterns are clinically significant.
Immunoassay of Murine t-PA, u-PA and PAI-1 Using Monoclonal Antibodies Raised in Gene-inactivated Mice
Authors: Declerck Paul J , Verstreken Maria , Collen Désiré J 
Published: July 2018

SummaryThree enzyme-linked immunosorbent assays for the quantitation of murine tissue-type plasminogen activator (t-PA), urokinase-type plasminogen aetivator (u-PA) and plasminogen activator inhibitor I (PAI-1), were developed using monoclonal antibodies raised against the autologous proteins in gene-inactivated mice. Dose-response was linear for t-PA and PAI-1 between 5 and 0.1 ng/ml and for u-PA between 50 and 1 ng/ml, with intra-assay, inter-assay and inter-dilution coefficients of variation of 6 to 14%. Assay recoveries of proteins (5 to 100 ng/ml) added to plasma were 73 to 95% for t-PA and PAI-1. Linear correlations (r = 0.65, r = 0.91 and r = 0.92, for t-PA, u-PA and PAI-1 respectively) were found between antigen and activity in plasma, urine and tissue extracts. Levels of t-PA and PAI-1 antigen in murine plasma were 2.5 ± 1.0 ng/ml (mean ± SD, n = 9) and 1.9 ± 0.6 ng/ml (mean ± SD, n = 8), respectively, in wild-type mice and undetectable in gene-inactivated mice. Bradykinin injection in mice provoked a 12-fold increase (p <0.0002) of t-PA and endotoxin injection an 80-fold increase (p <0.005) of PAI-1 levels. u-PA antigen levels in urine from wild-type mice ranged between 0.2 and 8.2 μ;g/ml (1.8 ± 1.9 μg/ml, mean ± SD, n = 17) and were undetectable in gene-inactivated mice.Thus, these assays may be useful for studies on the role of these proteins in tissue remodeling, atherosclerosis, embryogenesis, etc., in established mouse models. Gene-inactivated mice may constitute a general approach for the generation of monoclonal antibodies against the deficient translation products and for the development of specific immunoassays for murine proteins.
Shear-Induced Platelet Aggregation in Normal Subjects and Stroke Patients
Authors: Konstantopoulos Konstantinos , Grotta James C , Sills Cynthia , Wu Kenneth K , David Heliums J 
Published: July 2018

SummaryElevated levels of shear stress that occur in stenotic arteries may induce platelet aggregation and initiate thrombosis. Shear-induced platelet aggregation (SIPA) was studied in groups of ischemic stroke patients and normal subjects using a viscometric-flow cytometric technique. Twenty-three patients who sustained an ischemic stroke that was not of cardiac origin were included in this study, and were classified either as atherosclerotic (n = 15) or as lacunar (n = 8) stroke patients. The results show that shear stresses at the levels which occur in arteries partially occluded by atherosclerosis or vascular spasm strongly activate and aggregate platelets, and this response is much more pronounced in non-lacunar stroke patients who had documented atherosclerotic disease of their cerebral vessels. SIPA is not affected by the time of blood drawing after the onset of stroke suggesting that these platelet abnormalities are not transient but chronic. Furthermore, the extent of platelet activation detected by an anti-P-selectin monoclonal antibody and the proportion of neutrophil-platelet aggregates circulating in vivo are significantly higher in the atherosclerotic stroke patients studied at least one month after the onset of stroke. The results indicate that the enhanced platelet responses observed in atherosclerotic stroke patients are not consequences of ischemia, and therefore both platelet activation and elevated SIPA may be considered as important risk factors for stroke. The methodology developed in this work may be useful for characterization of platelet reactivity, and may contribute to our understanding of thrombotic mechanisms.
Thrombin Receptor Activating Peptide (TRAP) Stimulates Mitogenesis, c-fos and PDGF-A Gene Expression in Human Vascular Smooth Muscle Cells
Authors: Kanthou Chryso , Benzakour Omar , Patel Geeta , Deadman John , Kakkar Vijay Vir , Lupu Florea 
Published: July 2018

SummaryThe synthetic peptide SFLLRNPNDKYEPF, identical in sequence to the new amino-terminus of the thrombin receptor generated following cleavage by thrombin, acts as a thrombin receptor agonist/ activating peptide (TRAP). In this study, Northern blot analysis showed that cultured human vascular smooth muscle cells (HVSMC) express a thrombin receptor transcript. TRAP, in contrast to thrombin was shown to be a weak mitogen for HVSMC. A combination of TRAP and enzymatically-inactivated thrombin (PPACK-thrombin) which provides receptor occupancy, did not potentiate TRAP-induced mitogenesis, indicating that TRAP and PPACK-thrombin do not reproduce the mitogenic effect of enzymatically-active thrombin. Both thrombin and TRAP, induced the expression of c-fos and the PDGF-A gene in a pertussis toxin (PTX)-insensitive manner. Examination of thrombin and TRAP-treated cells by immunofluorescence staining followed by computer assisted image analysis revealed that thrombin and to a lesser extent TRAP induced PDGF-AA protein expression. Antibodies to PDGF-AA partially inhibited thrombin but not TRAP-induced mitogenesis in HVSMC. This study indicates that in addition to the common signalling pathways utilised by thrombin and TRAP, enzymatically-active thrombin activates other signalling pathways and hence TRAP does not mimic fully the biological effect of thrombin on HVSMC.
Induction of Thrombosis in a Mouse Model by IgG, IgM and IgA Immunoglobulins from Patients with the Antiphospholipid Syndrome
Authors: Pierangeli Silva S , Liu Xiao Wei , Barker John H , Anderson Gary , Harris E Nigel 
Published: July 2018

SummaryAntiphospholipid syndrome is a disorder of recurrent thrombosis and pregnancy losses associated with production of anticardiolipin antibodies and lupus anticoagulant positivity. Recently, we have adapted a mouse model of induced venous thrombosis to study the role of autoantibodies in thrombus formation. To determine whether immunoglobulins from patients with the antiphospholipid syndrome play a role in thrombosis, we injected groups of CDI mice either with immunoglobulins purified from seven patients with the antiphospholipid syndrome (nine preparations studied: four IgG, three IgM and two IgA) or with immunoglobulins of the same isotype from healthy controls. Seventy- two h after injection, a non-occlusive thrombus was induced in the femoral veins of experimental mice by a pinch injury; the thrombus areas as well as times of formation and disappearance of the thrombi were measured. Eight of the nine antiphospholipid syndrome immunoglobulin preparations caused a significant increase in mean thrombus area and a significant delay in mean thrombus disappearance time as compared with normal controls. To determine whether anticardiolipin antibodies might be involved, separate groups of mice were injected with affinity-purified IgG (n = 2) or IgM (n = 2) anticardiolipin antibodies or with normal immunoglobulins of the same isotype, and the effects on thrombus formation compared. Mean thrombus area and mean disappearance times were again significantly increased in all four groups injected with affinity-purified antibodies. This is the first study to show that anticardiolipin antibodies of IgG, IgM and IgA isotypes may play a role in thrombosis in vivo.
Molecular Epidemiology of Factor IX Germline Mutations in Mexican Hispanics: Pattern of Mutation and Potential Founder Effects
Authors: Thorland Erik C , Weinshenker Brian G , Liu Jing-zhong , Ketterling Rhett P , Vielhaber Erica L , Kasper Carol K , Ambriz Raul , Paredes Rogelio , Sommer Steve S 
Published: July 2018

SummaryGermline mutations in patients with hemophilia B generally have arisen within the past 150 years. Evidence suggests that these germline mutations generally result from endogenous processes. However, a unique pattern would be expected if a population were exposed to a physiologically important germline mutagen since mutagens generally produce characteristic patterns, or “fingerprints”, of mutation. To determine the pattern of mutation in Mexican Hispanics, the regions of likely functional significance in the factor IX gene were screened by di-deoxy fingerprinting (ddF) in 31 families with hemophilia B. Mutations were found in 30 of these families. Haplotype analysis was performed on individuals with identical mutations to help distinguish independent, recurrent mutations from founder effects. Analysis of these 30 mutations, along with 7 mutations reported previously in Mexican Hispanic families, reveals a pattern of independent mutation that is similar to the pattern of mutation observed in 127 U. S. Caucasian families (p = 0.89). These results may reflect either an underlying pattern of germline mutation due to endogenous processes or the presence of an ubiquitous mutagen. Further analyses of the recurrent mutations revealed that two mutations, T296M and R248Q, accounted for 19% of the mutations found in the Mexicans. Haplotype data suggest that the multiple occurrences of T296M and R248Q are associated with founder effects and that screening for these mutations may allow rapid mutation detection and carrier diagnosis in a significant minority of Mexican families with hemophilia B. These two mutations also are associated with founder effects in the U. S. Caucasian population. However, the haplotypes are different in these two populations, indicating independent origins. The occurrence of identical founder mutations in distinct populations provides evidence for the previous hypothesis that the number of different mutations giving rise to mild or borderline mild/moderate hemophilia B is small compared to deleterious mutations causing more severe disease.
Subcutaneous Low-Molecular-Weight Heparin Fragmin Versus Intravenous Unfractionated Heparin in the Treatment of Acute Non Massive Pulmonary Embolism: An Open Randomized Pilot Study
Authors: Meyer G , Brenot F , Pacouret G , Simonneau G , Juvin K Gillet , Charbonnier B , Sors H 
Published: July 2018

SummaryLow-molecular-weight heparins have been extensively investigated in the treatment of deep venous thrombosis but limited data are available concerning their use in pulmonary embolism. In an open, pilot, randomized study, we compare the safety and efficacy of Fragmin, a low-molecular-weight heparin with those of unfractionated heparin in 60 patients with non massive pulmonary embolism (Miller Index < 20). Thirty one patients received unfractionated heparin intravenously and 29 received a fixed dose of 120 Anti-Xa IU/kg of Fragmin administered subcutaneously twice a day for 10 days. There was no pulmonary embolism recurrence nor major bleeding in either group during the treatment period. The decrease in pulmonary vascular obstruction on perfusion lung scan between day 0 and day 10 was 17 ± 13% in the Fragmin group and 16 ± 13% in the heparin group (NS). These results indicate that Fragmin may be a safe and effective treatment of submassive pulmonary embolism.
Gelatin Use Impairs Platelet Adhesion during Cardiac Surgery
Authors: Tabuchi Norlyuki , de Haan Jacob , Gallandat Huet Rolf C G , Boonstra Plet W , van Oeveren Willem 
Published: July 2018

SummaryArtificial colloids based on gelatin are used as plasma expander to replace donor blood products. In laboratory experiments, gelatin reduced both the velocity and extend of platelet agglutination by ristocetin, and only the agglutination velocity by polybrene (p <0.05). Furthermore, gelatin delayed the in-vitro platelet plug formation under shear-stress in the absence of ADP (p <0.05), whereas gelatin induced no delay in the presence of ADP. Thus, after induction of vWF release from platelets by polybrene or ADP, platelet function was normal. These results indicate that gelatin affects in particular the functionality of plasma-vWF and partly inhibits platelet adhesion.These negative effects of gelatin on hemostasis were demonstrated in two clinical studies during cardiac surgery. In a randomized study of sixty patients undergoing cardiac surgery, gelatin as prime in the heart-lung machine appeared to result in diminished efficacy of aprotinin on hemostasis, whereas it did not affect hemostasis in non-aprotinin patients. An additional retrospective clinical study showed that only high dose of gelatin affected hemostasis. This suggests a limited role of plasma-vWF and a strong back-up mechanism of platelet-vWF in achieving hemostasis.
Pharmacokinetics and Tolerance of the Natural Pentasaccharide (SR90107/ORG31540) with High Affinity to Antithrombin III in Man
Authors: Boneu B , Necciari J , Cariou R , Sié P , Gabaig A M , Kieffer G , Dickinson J , Lamond G , Moelker H , Mant T , Magnani H 
Published: July 2018

SummaryThis paper reports the results of the first administration of the synthetic natural pentasaccharide with high affinity to antithrombin III (NP) in man. The study was mainly focused upon the pharmacokinetic properties and general tolerance of the compound. Subcutaneous injections of doses <1.43 mg (1000 anti Xa IU) did not generate measurable anti-Xa activities. After subcutaneous injection of increasing doses from 1.43 to 22.9 mg (1000 to 16000 anti-Xa IU) to young healthy volunteers, it was found that the maximal concentration (Cmax) and the area under curve (AUC) were linearly correlated to the dose, that the total plasma clearances (Cl) were constant and almost 3 times lower than those of the current low molecular weight heparins. Cmax were reached between 1 h and 3 h after the injection and the half-lives (t1/2) were remarkably constant (13.1 h to 13.9 h). During the first 24 h following the injection, around 50% of the total administered dose was recovered in the urine in an active form, indicating that kidney plays a major role in the elimination of NP. Consistent with these results, when NP was administered to healthy elderly volunteers having a lower creatinine clearance, the half-life of the compound was longer and the clearance lower. At doses exceeding 22.9 mg, Cmax, and AUC were slightly lower than expected, the percentage of the dose recovered in the urine and the total apparent plasma clearance increased, suggesting that the excess of NP unbound to antithrombin III was excreted faster. NP was also administered at various dosages once or twice a day for 7 days to 20 elderly volunteers. Due to the long half-life of the compound the “steady state” was obtained 2 to 3 days after the first injection at which the mean Cmax was increased 1.5 to 2 times. The general tolerance of the compound was excellent. No relevant prolongations of the prothrombin time, of the activated partial thromboplastin time or of the bleeding time were observed. A re-bleeding phenomenon of the bleeding time incision, probably related to friability of the haemostatic plug, occurred in 3 subjects treated with the highest dose regimens: single injection of 26.6 mg (20000 anti-Xa IU) (young volunteers) and repeated injections of 11.4 mg (8000 anti-XaIU) once a day for 7 days (elderly volunteers). At these times, plasma NP concentrations were between 2.9 and 3.6 μg ⋅ ml-1 (2 and 2.5 anti-Xa IU ⋅ ml-1).
Modulation of Platelet Activation In Vitro by Thrombopoietin
Authors: Kojima Hiroshi , Hamazaki Yoko , Nagata Yuka , Todokoro Kazuo , Nagasawa Toshiro , Abe Tsukasa 
Published: July 2018

SummaryEffect of human recombinant thrombopoietin (TPO) on platelet activation in vitro was studied. Although TPO by itself did not cause platelet aggregation, it upregulated ADP-induced aggregation, especially the second wave of aggregation. This effect was dose-dependent for up to 5 ng/ml of TPO. When platelets were activated by epinephrine, collagen, or α-thrombin, similar effect was observed. However, TPO did not affect A23187- or PMA-induced aggregation, suggesting that TPO may have modulated the signal transduction pathway upstream of inositol 1,4,5-trisphosphate and diacylglycerol production. TPO also upregulated thrombin-induced α-granule secretion. To clarify the involvement of protein tyrosine phosphorylation, platelets were activated by TPO and/or suboptimal concentration of ADP, then tyrosine phosphorylation was detected by immunoblot analysis, using anti-phosphotyrosine monoclonal antibody. TPO by itself caused significant tyrosine phosphorylation of 146,130,122,108, 97,94, and 88 kDa proteins. Further, by using antibodies against signal transduction molecules for immunoprecipitation, we observed the significant tyrosine phosphorylation in Jak2 and Tyk2 molecules after TPO-stimulation. The results of the present experiment clearly indicate that TPO directly activated platelets and modulated intracellular signal transduction pathway.