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Sample records for direct factor xa

  1. Engineered factor Xa variants retain procoagulant activity independent of direct factor Xa inhibitors.

    PubMed

    Verhoef, Daniël; Visscher, Koen M; Vosmeer, C Ruben; Cheung, Ka Lei; Reitsma, Pieter H; Geerke, Daan P; Bos, Mettine H A

    2017-09-13

    The absence of an adequate reversal strategy to prevent and stop potential life-threatening bleeding complications is a major drawback to the clinical use of the direct oral inhibitors of blood coagulation factor Xa. Here we show that specific modifications of the substrate-binding aromatic S4 subpocket within the factor Xa active site disrupt high-affinity engagement of the direct factor Xa inhibitors. These modifications either entail amino-acid substitution of S4 subsite residues Tyr99 and/or Phe174 (chymotrypsinogen numbering), or extension of the 99-loop that borders the S4 subsite. The latter modifications led to the engineering of a factor Xa variant that is able to support coagulation in human plasma spiked with (supra-)physiological concentrations of direct factor Xa inhibitors. As such, this factor Xa variant has the potential to be employed to bypass the direct factor Xa inhibitor-mediated anticoagulation in patients that require restoration of blood coagulation.A major drawback in the clinical use of the oral anticoagulants that directly inhibit factor Xa in order to prevent blood clot formation is the potential for life threatening bleeding events. Here the authors describe factor Xa variants that are refractory to inhibition by these anticoagulants and could serve as rescue agents in treated patients.

  2. A specific antidote for reversal of anticoagulation by direct and indirect inhibitors of coagulation factor Xa.

    PubMed

    Lu, Genmin; DeGuzman, Francis R; Hollenbach, Stanley J; Karbarz, Mark J; Abe, Keith; Lee, Gail; Luan, Peng; Hutchaleelaha, Athiwat; Inagaki, Mayuko; Conley, Pamela B; Phillips, David R; Sinha, Uma

    2013-04-01

    Inhibitors of coagulation factor Xa (fXa) have emerged as a new class of antithrombotics but lack effective antidotes for patients experiencing serious bleeding. We designed and expressed a modified form of fXa as an antidote for fXa inhibitors. This recombinant protein (r-Antidote, PRT064445) is catalytically inactive and lacks the membrane-binding γ-carboxyglutamic acid domain of native fXa but retains the ability of native fXa to bind direct fXa inhibitors as well as low molecular weight heparin-activated antithrombin III (ATIII). r-Antidote dose-dependently reversed the inhibition of fXa by direct fXa inhibitors and corrected the prolongation of ex vivo clotting times by such inhibitors. In rabbits treated with the direct fXa inhibitor rivaroxaban, r-Antidote restored hemostasis in a liver laceration model. The effect of r-Antidote was mediated by reducing plasma anti-fXa activity and the non-protein bound fraction of the fXa inhibitor in plasma. In rats, r-Antidote administration dose-dependently and completely corrected increases in blood loss resulting from ATIII-dependent anticoagulation by enoxaparin or fondaparinux. r-Antidote has the potential to be used as a universal antidote for a broad range of fXa inhibitors.

  3. Edoxaban: a new oral direct factor xa inhibitor.

    PubMed

    Camm, A John; Bounameaux, Henri

    2011-08-20

    Edoxaban is an oral direct factor Xa inhibitor that is currently undergoing investigation in phase III clinical trials for the prevention of stroke in patients with atrial fibrillation (AF) and for the prevention and treatment of venous thromboembolic events (VTE). Factor Xa is an attractive target for anticoagulant treatment, as it is the primary and rate-limiting source of amplification in the coagulation cascade. Edoxaban is a competitive inhibitor of factor Xa and has >10 000-fold greater selectivity for factor Xa relative to thrombin. In phase I clinical trials, the anticoagulant effects of edoxaban included dose-dependent increases in activated partial thromboplastin time and prothrombin time following single edoxaban doses of 10-150 mg and after multiple ascending doses (60 mg twice daily, 90 mg daily and 120 mg daily). The anticoagulant effects of edoxaban were rapid in onset (time to peak plasma concentration 1-2 hours) and sustained for up to 24 hours. Prolongation of bleeding time in 8% of subjects was >9.5 minutes (none of which appeared to be clinically significant) 2 hours after initial dosing, and was independent of edoxaban dose, formulation or dietary state. In general, plasma edoxaban concentrations were linearly correlated with coagulation parameters. Phase II clinical trials in patients with AF and VTE suggest that the edoxaban 30 mg once-daily and 60 mg once-daily regimens had a similar or better safety profile compared with dose-adjusted warfarin (international normalized ratio 2.0-3.0) in terms of bleeding events, and that edoxaban was not associated with hepatotoxicity. In addition, edoxaban was associated with statistically significant dose-dependent reductions in VTE after orthopaedic surgery compared with placebo or dalteparin sodium. Further clinical investigation of the efficacy and safety of once-daily edoxaban is being conducted in phase III clinical trials in comparison with warfarin in patients with AF in the phase III

  4. Chromogenic laboratory assays to measure the factor Xa-inhibiting properties of apixaban--an oral, direct and selective factor Xa inhibitor.

    PubMed

    Becker, Richard C; Yang, Hongqiu; Barrett, Yuchen; Mohan, Puneet; Wang, Jessie; Wallentin, Lars; Alexander, John H

    2011-08-01

    An ability to readily determine an anticoagulant effect with an emerging class of direct, active site, oral factor Xa inhibitors is viewed by the medical community as attractive and by some as an absolute requirement for their use in clinical practice. We performed a pharmacokinetic and pharmacodynamic substudy in APPRAISE-1-a study of apixaban in patients with acute coronary syndrome(ACS). A total of 1691 patients had blood sampled for apixaban plasma concentrations using mass spectrometry/high performance liquid chromatography and anti-Xa activity using a chromogenic assay employing either low molecular weight heparin or apixaban as reference standards. Anti-Xa activity, determined by either anti-Xa-LMWH (r = 0.9671; P < 0.0001) or anti-Xa-apixaban (r = 0.9669; P < 0.0001) correlated strongly and in a linear fashion with apixaban plasma concentrations. The correlations for each method were equally strong at low (<100 ng/ml) (r = 0.86, P < 0.0001; r = 0.85, P < 0.0001), intermediate(100-200 ng/ml) (r = 0.73, P < 0.0001; r = 0.69, P < 0.0001) and high (>200 ng/ml) (r = 0.91, P < 0.0001; r = 0.91, P < 0.0001) plasma concentrations of apixaban, respectively. Our pharmacokinetic and pharmacodynamic substudy suggests that an apixaban-mediated anticoagulant effect can be detected even at very low plasma concentrations using a standard laboratory chromogenic anti-Xa assay with either LMWH or apixaban calibrators. While establishing parameters for safety and efficacy will require further investigation, an ability to discern the presence of a drug effect may provide clinically useful information.

  5. Future therapeutic directions for factor Xa inhibition in the prophylaxis and treatment of thrombotic disorders.

    PubMed

    Turpie, Alexander G G

    2003-11-15

    The targeted mechanism of factor Xa inhibition has been studied extensively, initially as prophylaxis for venous thromboembolism (VTE) in the orthopedic surgical setting. Future therapeutic directions for selective factor Xa inhibition in the management of other thrombotic diseases are discussed. Thromboembolic diseases can occur in the venous or arterial sides of the circulatory system. Factor Xa inhibition is a targeted approach to anticoagulation that resulted from significant advances in our understanding of the coagulation cascade. The factor Xa inhibitor fondaparinux has been studied extensively in the orthopedic surgical setting for the prophylaxis of VTE. Current investigations that are under way or completed evaluate the efficacy and safety of fondaparinux for the management of various thrombotic diseases. The future development of fondaparinux resides primarily in three therapeutic areas: prevention of VTE, treatment of VTE, and treatment of acute coronary syndromes. For the prevention of VTE, fondaparinux has been studied as extended prophylaxis following hip fracture surgery (PENTHIFRA Plus), for use in high-risk abdominal surgical patients (PEGASUS and APOLLO), and for use in medical patients (ARTEMIS). Studies evaluating fondaparinux for the treatment of VTE are part of the large MATISSE clinical program (MATISSE DVT and MATISSE PE). Fondaparinux was investigated in phase 2 studies for the treatment of acute coronary syndromes, including acute ST-segment myocardial infarction (PENTALYSE) and unstable angina (PENTUA). Encouraging data from these trials are the basis for phase 3 programs in this area (MICHELANGELO). The orthopedic prophylactic and nonorthopedic clinical programs for fondaparinux in the management of thrombosis support the concept that targeted inhibition of coagulation is an effective advance in antithrombotic therapy.

  6. Anticoagulation beyond direct thrombin and factor Xa inhibitors: indications for targeting the intrinsic pathway?

    PubMed

    van Montfoort, Maurits L; Meijers, Joost C M

    2013-08-01

    Antithrombotic drugs like vitamin K antagonists and heparin have been the gold standard for the treatment and prevention of thromboembolic disease for many years. Unfortunately, there are several disadvantages of these antithrombotic drugs: they are accompanied by serious bleeding problems, it is necessary to monitor the therapeutic window, and there are various interactions with food and other drugs. This has led to the development of new oral anticoagulants, specifically inhibiting either thrombin or factor Xa. In terms of effectiveness, these drugs are comparable to the currently available anticoagulants; however, they are still associated with issues such as bleeding, reversal of the drug and complicated laboratory monitoring. Vitamin K antagonists, heparin, direct thrombin and factor Xa inhibitors have in common that they target key proteins of the haemostatic system. In an attempt to overcome these difficulties we investigated whether the intrinsic coagulation factors (VIII, IX, XI, XII, prekallikrein and high-molecular-weight kininogen) are superior targets for anticoagulation. We analysed epidemiological data concerning thrombosis and bleeding in patients deficient in one of the intrinsic pathway proteins. Furthermore, we discuss several thrombotic models in intrinsic coagulation factor-deficient animals. The combined results suggest that intrinsic coagulation factors could be suitable targets for anticoagulant drugs.

  7. Recent advances in the discovery and development of direct coagulation factor Xa inhibitors.

    PubMed

    Gould, W R; Leadley, R J

    2003-01-01

    Coronary heart disease (CHD) is the leading cause of mortality and morbidity in the United States. Currently, there are approximately 12 million Americans with CHD, which is most frequently caused by atherosclerosis. The thrombotic complications of atherosclerosis, such as acute coronary syndrome and ischemic stroke, can be fatal and those who survive such events have a far greater risk of future cardiovascular events. This huge medical need cries out for improved novel anticoagulants, antiplatelet agents, and profibrinolytic agents. These agents will successfully respond to the medical need by providing safe, effective, and easily administered treatments that have little, if any, drug and food interactions and that require minimal monitoring. The currently approved antiplatelet agent, clopidogrel, has satisfied some of these requirements and has played a large role in expanding the antithrombotic market over the past few years. New antithrombotics approaching the marketplace, such as the prodrug thrombin inhibitor ximelagatran, have promise in expanding the antithrombotic market further. Over the past two decades, the pharmaceutical industry has mounted a huge effort to develop antithrombotics that function by inhibiting key enzymes positioned at "higher" levels of the coagulation system. Direct inhibitors of factor Xa, which may provide a better safety and efficacy profile than currently available agents, appear to be the next major class of antithrombotic agents poised to take the pharmaceutical industry one step closer to delivering the ideal antithrombotic agent. This review focuses on recent innovations in the discovery and development of potent parenteral and oral direct factor Xa inhibitors.

  8. Anticoagulation by factor Xa inhibitors

    PubMed Central

    Orfeo, Thomas; Butenas, Saulius; Brummel-Ziedins, Kathleen E.; Gissel, Matthew; Mann, Kenneth G.

    2010-01-01

    Summary Background Therapeutic agents that regulate blood coagulation are critical to the management of thrombotic disorders, with the selective targeting of factor (f)Xa emerging as a promising approach. Objective To assess anticoagulant strategies targeting fXa. Methods A deterministic computational model of tissue factor (Tf)-initiated thrombin generation and two empirical experimental systems (a synthetic coagulation proteome reconstruction using purified proteins and a whole blood model) were used to evaluate clinically relevant examples of the two available types of fXa directed anticoagulants (an antithrombin (AT)-dependent agent, fondaparinux, and an AT-independent inhibitor, Rivaroxaban) in experimental regimens relevant to long term (suppression of new Tf-initiated events) and acute (suppression of ongoing coagulation processes) clinical applications. Results Computational representations of each anticoagulant’s efficacy in suppressing thrombin generation over a range of anticoagulant concentrations in both anticoagulation regimens were validated by results from corresponding empirical reconstructions and were consistent with those recommended for long term and acute clinical applications respectively. All three model systems suggested that Rivaroxaban would prove more effective in the suppression of an ongoing coagulation process than fondaparinux, reflecting its much higher reactivity toward the prothrombinase complex. Conclusion The success of fondaparinux in acute settings in vivo is not explained solely by its properties as an fXa inhibitor. We have reported that fIXa contributes to the long term capacity of clot-associated catalysts to restart a coagulation process [Orfeo T et al. J Biol Chem 2008;283:9776], suggesting that the enhanced anti-fIXa activity of fondaparinux-AT may be critical to its success in acute settings in vivo. PMID:20492473

  9. Potent Direct Inhibitors of Factor Xa Based on the Tetrahydroisoquinoline Scaffold

    PubMed Central

    Al-Horani, Rami A.; Mehta, Akul Y.; Desai, Umesh R.

    2012-01-01

    Direct inhibition of coagulation factor Xa (FXa) carries significant promise for developing effective and safe anticoagulants. Although a large number of FXa inhibitors have been studied, each can be classified as either possessing a highly flexible or a rigid core scaffold. We reasoned that an intermediate level of flexibility will provide high selectivity for FXa considering that its active site is less constrained in comparison to thrombin and more constrained as compared to trypsin. We studied several core scaffolds including 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid for direct FXa inhibition. Using a genetic algorithm-based docking and scoring approach, a promising candidate 23 was identified, synthesized, and found to inhibit FXa with a Ki of 28 μM. Optimization of derivative 23 resulted in the design of a potent dicarboxamide 47, which displayed a Ki of 135 nM. Dicarboxamide 47 displayed at least 1852-fold selectivity for FXa inhibition over other coagulation enzymes and doubled PT and aPTT of human plasma at 17.1 μM and 20.2 μM, respectively, which are comparable to those of clinically relevant agents. Dicarboxamide 47 is expected to serve as an excellent lead for further anticoagulant discovery. PMID:22770607

  10. The direct factor Xa inhibitor Rivaroxaban reduces platelet activation in congestive heart failure.

    PubMed

    Flierl, Ulrike; Fraccarollo, Daniela; Micka, Jan; Bauersachs, Johann; Schäfer, Andreas

    2013-08-01

    Platelet activation in congestive heart failure (CHF) contributes to an increased risk for thromboembolic complications. Rivaroxaban, the first oral direct FXa inhibitor is approved in Europe for prevention and treatment of venous thrombosis, pulmonary embolism, and prevention of thromboembolic events in atrial fibrillation. As heart failure is an important risk factor for thromboembolism and increased platelet activation is common in heart failure, we investigated the potential effect of Rivaroxaban treatment on platelets in an experimental CHF model. Chronic myocardial infarction was induced in male Wistar rats by coronary ligation. Rats were randomized to placebo or Rivaroxaban (3 and 10mg/kg once daily). After 10 weeks platelet activation was assessed. Platelet-bound fibrinogen, detected by flow-cytometry, was significantly increased in CHF-Placebo (p<0.05) and reduced following treatment with Rivaroxaban (p<0.05 vs. CHF-Placebo). ADP-induced aggregation was significantly enhanced in CHF-Placebo vs. sham-operated animals (p<0.05) and normalized following chronic FXa inhibition (p<0.05 vs. CHF-Placebo). In separate in vitro experiments, attenuated platelet aggregation was present after incubating whole blood directly with Rivaroxaban but absent when the experiment was performed in platelet-rich plasma only. Thus, a direct effect on platelets could be excluded. Chronic direct factor Xa inhibition using Rivaroxaban reduces platelet activation in CHF rats by attenuating the secondary phase of ADP-induced platelet aggregation. Thus, Rivaroxaban may constitute a useful approach to prevent thromboembolic complications and reduce platelet activation in CHF at the same time. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Discovery of glycyrrhetinic acid as an orally active, direct inhibitor of blood coagulation factor xa.

    PubMed

    Jiang, Lilong; Wang, Qiong; Shen, Shu; Xiao, Tongshu; Li, Youbin

    2014-03-01

    Factor Xa (FXa) plays an important role in blood coagulation. This study investigated glycyrrhetinic acid, a small molecule derived from Chinese herbs, and whether it has a direct inhibitory effect on FXa to display its anticoagulant activity. Enzyme activities of FXa, plasmin, trypsin and thrombin, inhibition of FXa enzyme kinetics and plasma clotting time by glycyrrhentinic acid were performed in vitro. A rat tail-bleeding model and a rat venous stasis model were also used to evaluate in vivo tail-bleeding time and thrombus formation, respectively. Glycyrrhetinic acid in vitro directly inhibited FXa uncompetitivly with IC50 of 32.6 ± 1.24 μmol/L, and displayed 2-, 14- and 20-fold selectivity for FXa when compared to plasmin, thrombin and trypsin, respectively. The plasma clotting time was increased in a dose-dependent manner. The prothrombin time doubled (PT2), when the concentration of glycyrrhetinic acid reached 2.02 mmol/L. During in vivo experiments intragastric administration of glycyrrhetinic acid caused a dose-dependent reduction in thrombus weight on the rat venous stasis model (all P<0.05). 50 mg/kg glycyrrhetinic acid resulted in 34.8% of venous thrombus weight lost, compared to the control. In addition, 200, 300 and 400 mg/kg doses of glycyrrhetinic acid caused a moderate hemorrhagic effect in the rat tail-bleeding model by prolonging bleeding time 1.1-, 1.5- and 1.9-fold compared to the control, respectively. Glycyrrhetinic acid is a direct inhibitor of FXa that is effective by oral administration, and with further research could be used to treat blood coagulation disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Antithrombotic potential of GW813893: a novel, orally active, active-site directed factor Xa inhibitor.

    PubMed

    Abboud, Melanie A; Needle, Saul J; Burns-Kurtis, Cynthia L; Valocik, Richard E; Koster, Paul F; Amour, Augustin J; Chan, Chuen; Brown, David; Chaudry, Laiq; Zhou, Ping; Patikis, Angela; Patel, Champa; Pateman, Anthony J; Young, Rob J; Watson, Nigel S; Toomey, John R

    2008-07-01

    Factor Xa (FXa) has been a target of considerable interest for drug development efforts aimed at suppressing thrombosis. In this report, a new orally active, small molecule, active-site directed FXa inhibitor, GW813893, has been profiled in a succession of in vitro and in vivo assays involved in its preclinical characterization as a potential antithrombotic therapeutic. In vitro profiling of GW813893 consisted of assessing its inhibitory potential against FXa and a broad panel of related and unrelated enzymes and receptors. Additionally, the FXa inhibition potential of GW813893 was assessed in prothrombinase and plasma-based clotting assays. In vivo characterization of GW813893 consisted of thrombosis studies in a rat inferior vena cava model, a rat carotid artery thrombosis model, and a rabbit jugular thrombosis model. Bleeding studies were conducted in a rat tail transection model. Ex vivo determinations of compound effects on FX and clotting activity were also undertaken. GW813893 was more than 90-fold selective over all enzymes tested, and it inhibited FXa and prothrombinase activity with a Ki of 4.0 nM and 9.7 nM, respectively. In vivo, GW813893 concentration-dependently suppressed thrombotic activity in all models tested. The antithrombotic activity correlated with the suppression of plasma-based clotting activity and the inhibition of plasma FX activity (P < 0.02). Over the antithrombotic dose-range, an increased bleeding diathesis was not observed. These experiments demonstrate that GW813893 is a potent, selective, orally active inhibitor of FXa. The data suggest that GW813893 has robust antithrombotic potential at doses that have no detectable hemostasis liability. Collectively, the profile suggests that GW813893 has the preclinical pharmacology underpinnings of an oral antithrombotic therapeutic.

  13. Effect of famotidine on the pharmacokinetics of apixaban, an oral direct factor Xa inhibitor

    PubMed Central

    Upreti, Vijay V; Song, Yan; Wang, Jessie; Byon, Wonkyung; Boyd, Rebecca A; Pursley, Janice M; LaCreta, Frank; Frost, Charles E

    2013-01-01

    Background Apixaban is an oral, selective, direct factor Xa inhibitor approved for thromboprophylaxis after orthopedic surgery and stroke prevention in patients with atrial fibrillation, and under development for treatment of venous thromboembolism. This study investigated the effect of a gastric acid suppressant, famotidine (a histamine H2-receptor antagonist), on the pharmacokinetics of apixaban in healthy subjects. Methods This two-period, two-treatment crossover study randomized 18 healthy subjects to receive a single oral dose of apixaban 10 mg with and without a single oral dose of famotidine 40 mg administered 3 hours before dosing with apixaban. Plasma apixaban concentrations were measured up to 60 hours post-dose and pharmacokinetic parameters were calculated. Results Famotidine did not affect maximum apixaban plasma concentration (Cmax) or area under the plasma concentration-time curve from zero to infinite time (AUC∞). Point estimates for ratios of geometric means with and without famotidine were close to unity for Cmax (0.978) and AUC∞ (1.007), and 90% confidence intervals were entirely contained within the 80%–125% no-effect interval. Administration of apixaban alone and with famotidine was well tolerated. Conclusion Famotidine does not affect the pharmacokinetics of apixaban, consistent with the physicochemical properties of apixaban (lack of an ionizable group and pH-independent solubility). Apixaban pharmacokinetics would not be affected by an increase in gastrointestinal pH due to underlying conditions (eg, achlorhydria), or by gastrointestinal pH-mediated effects of other histamine H2-receptor antagonists, antacids, or proton pump inhibitors. Given that famotidine is also an inhibitor of the human organic cation transporter (hOCT), these results indicate that apixaban pharmacokinetics are not influenced by hOCT uptake transporter inhibitors. Overall, these results support that apixaban can be administered without regard to coadministration

  14. Safety, tolerability, pharmacodynamics, and pharmacokinetics of rivaroxaban--an oral, direct factor Xa inhibitor--are not affected by aspirin.

    PubMed

    Kubitza, Dagmar; Becka, Michael; Mueck, Wolfgang; Zuehlsdorf, Michael

    2006-09-01

    Rivaroxaban (BAY 59-7939) is an oral, direct Factor Xa inhibitor in advanced clinical development for the prevention and treatment of thromboembolic disorders. This was a randomized, 2-way crossover study in healthy male subjects, with an aspirin run-in period, to examine whether aspirin influences the safety, tolerability, pharmacodynamics, and pharmacokinetics of rivaroxaban. All treatments were well tolerated; drug-related adverse events were mild and transient. Aspirin did not alter the effects of rivaroxaban on Factor Xa activity or clotting tests. Platelet aggregation and bleeding time were not affected by rivaroxaban, and rivaroxaban did not influence the effects of aspirin on these parameters to a clinically relevant extent. Aspirin did not affect the pharmacokinetics of rivaroxaban, including the fraction unbound. This study suggests that there is no clinically relevant interaction between rivaroxaban and aspirin and that the 2 drugs could be administered concomitantly at the doses used in this study.

  15. Novel direct factor Xa inhibitory compounds from Tenebrio molitor with anti-platelet aggregation activity.

    PubMed

    Lee, Wonhwa; Kim, Mi-Ae; Park, InWha; Hwang, Jae Sam; Na, MinKyun; Bae, Jong-Sup

    2017-08-24

    Tenebrio molitor is an edible insect that has antimicrobial, anticancer, and antihypertensive effects. The aim of this study was to identify the unreported bioactive compounds from T. molitor larvae with inhibitory activities against factor Xa (FXa) and platelet aggregation. Isolated compounds were evaluated for their anti-FXa and anti-platelet aggregation properties by monitoring clotting time, platelet aggregation, FXa activity, and thrombus formation. A diketopiperazine (1, cyclo(L-Pro-L-Tyr)) and a phenylethanoid (2, N-acetyltyramine) were isolated and inhibited the catalytic activity of FXa in a mixed inhibition model and inhibited platelet aggregation induced by adenosine diphosphate (ADP) and U46619. They inhibited ADP- and U46619-induced phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) and the expression of P-selectin and PAC-1 in platelets. They also improved the production of nitric oxide and inhibited the oversecretion of endothelin-1 compared to that of the ADP- or U46619-treated group. In an animal model of arterial and pulmonary thrombosis, the isolated compounds showed enhanced antithrombotic effects. They also elicited anticoagulant effects in mice. Compounds 1-2 inhibited ADP-, collagen-, or U46619-induced platelet aggregation and showed similar anti-thrombotic efficacy to rivaroxaban, a positive control. Therefore, 1-2 could serve as candidates and provide scaffolds for the development of new anti-FXa and anti-platelet drugs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Population Pharmacokinetic and Pharmacodynamic Modeling Analysis of GCC‐4401C, a Novel Direct Factor Xa Inhibitor, in Healthy Volunteers

    PubMed Central

    Choi, HY; Choi, S; Kim, YH

    2016-01-01

    GCC‐4401C, an orally active direct factor Xa inhibitor that is similar to rivaroxaban, is currently under development for venous thromboembolic disease (VTE). The purpose of this study was to characterize the pharmacokinetics (PKs) and pharmacodynamics (PDs) of GCC‐4401C by population modeling analysis and to predict proper dosage regimens compared to rivaroxaban using data from two phase I clinical studies. Plasma GCC‐4401C concentrations over time were best described by a two‐compartment linear model and body weight was associated with central volume of distribution. Relevant PD markers generally changed in a dose‐dependent manner and were described well with sigmoid, simple maximum effect, or linear models. GCC‐4401C was absorbed more rapidly than rivaroxaban. Comparisons based on simulations of PD marker changes over time suggest that 20 mg and 40 mg of GCC‐4401C administered under fasted status are comparable to 10 mg and 20 mg of rivaroxaban under fed status. PMID:27511836

  17. Apixaban, a direct factor Xa inhibitor, inhibits tissue-factor induced human platelet aggregation in vitro: comparison with direct inhibitors of factor VIIa, XIa and thrombin.

    PubMed

    Wong, Pancras C; Jiang, Xiaosui

    2010-08-01

    Apixaban is an oral, direct and highly selective factor Xa (FXa) inhibitor in late-stage clinical development. This study evaluated the in vitro effect of apixaban on human platelet aggregation induced by thrombin derived via the extrinsic pathway. Direct inhibitors of FXa (rivaroxaban), FVIIa (BMS-593214), thrombin (dabigatran, argatroban) and FXIa (BMS-262084) were included for comparison. Citrated human platelets-rich plasma (PRP) was treated with 50 mg/ml corn trypsin inhibitor (to block the contact factor pathway) and 3 mM H-Gly-Pro-Arg-Pro-OH-AcOH (to prevent fibrin polymerisation). Human tissue factor (TF) (Innovin; dilution 1:1,000 to 1:1,500) plus 7.5 mM CaCl2 was added to PRP pre-incubated with vehicle or increasing concentrations of inhibitors. The TF-induced platelet aggregation was measured by optical aggregometry. TF produced 85 +/- 3% aggregation of human platelets in the vehicle-treated group (n=10). Apixaban and other factor inhibitors, except the FXIa inhibitor, inhibited TF-induced platelet aggregation with IC50 (nM) values as follows: 4 +/- 1 (apixaban), 8 +/- 2 (rivaroxaban), 13 +/- 1 (BMS-593214), 46 +/- 1 (dabigatran) and 79 +/- 1 (argatroban). BMS-262084 (IC50 = 2.8 nM vs. human FXIa) had no effect on TF-induced platelet aggregation at 10 microM. These inhibitors at 10 microM had no effect on platelet aggregation induced by ADP and collagen, as expected from their mechanism of action. This study demonstrates that inhibition of thrombin generation by blocking upstream proteases (FVIIa and FXa) in the blood coagulation cascade is as effective as direct thrombin inhibition in preventing TF-induced platelet aggregation. Under these experimental conditions, a FXIa inhibitor did not prevent TF-induced platelet aggregation.

  18. The effects of direct factor Xa inhibitor (Rivaroxaban) on the human osteoblastic cell line SaOS2.

    PubMed

    Gigi, Roy; Salai, Moshe; Dolkart, Oleg; Chechik, Ofir; Katzburg, Sarah; Stern, Naftali; Somjen, Dalia

    2012-01-01

    Thromboprophylaxis reduces the risk of surgery-related deep vein thrombosis, but anticoagulants were associated with systemic osteoporosis, a known risk factor for poor fracture healing. Rivaroxaban (XARELTO(®)) is a novel anticoagulant with specific ability to inhibit factor Xa, a serine endopeptidase, which plays a key role in coagulation. This study investigated the direct effects of rivaroxaban on bone biology using an in vitro cell culture model from the human female osteoblastic cell line SaOS2. Cells at subconfluence were treated for 24 hr with different concentrations of rivaroxaban and analyzed for DNA synthesis and creatine kinase- and alkaline phosphatase-specific activities, and were treated 21 days for analyzing mineralization. Rivaroxaban (0.01-50 μg/ml) dose-dependently inhibited up to 60% DNA synthesis of the cells. Creatine kinase-specific activity was also inhibited dose-dependently to a similar extent by the same concentrations. Alkaline phosphatase-specific activity was dose-dependently inhibited but only up to 30%. Cell mineralization was unaffected by 10 μg/ml rivaroxaban. This model demonstrated a significant rivaroxaban-induced reduction in osteoblastic cell growth and energy metabolism, and slight inhibition of the osteoblastic marker, alkaline phosphatase, while osteoblastic mineralization was unaffected. These findings might indicate that rivaroxaban inhibits the first stage of bone formation but does not affect later stages (i.e., bone mineralization).

  19. Effects of the oral, direct factor Xa inhibitor apixaban on routine coagulation assays and anti-FXa assays.

    PubMed

    Hillarp, A; Gustafsson, K M; Faxälv, L; Strandberg, K; Baghaei, F; Fagerberg Blixter, I; Berndtsson, M; Lindahl, T L

    2014-09-01

    Apixaban is an oral direct factor Xa inhibitor developed for the prophylaxis and treatment of thromboembolic disorders. Laboratory monitoring is not necessary, but the effects on common coagulation reagents and assays constitute clinically valuable information. To investigate the effects of apixaban on commonly used coagulation methods, and to evaluate anti-FXa assays for specific determination of the drug concentration. Apixaban was added to plasma from healthy subjects in the concentration range 0-1000 μg L(-1) , and analyses were performed with different reagents for activated partial thromboplastin time (APTT), prothrombin time (PT), antithrombin, protein C, and protein S. A lupus anticoagulant assay and an APTT assay with varying phospholipid concentrations were used to study the phospholipid dependence. In general, apixaban showed fewer effects in vitro than have been shown for rivaroxaban, another direct FXa inhibitor. The concentration needed to double the APTT varied between 2200 and 4700 μg L(-1) , and the concentration needed to double the PT varied between 700 and 3900 μg L(-1) . The effects on antithrombin, protein C and protein S assays were dependent on the type of reagent. Apixaban did not cause false-positive lupus anticoagulant results. Chromogenic anti-FXa assays showed linear dose-response curves with apixaban. Therapeutic concentrations of apixaban variably affect different assay groups, and even different reagents within an assay group. The effects were much smaller than with rivaroxaban. The use of APTT and/or PT assays to screen the anticoagulant activity of apixaban cannot be recommended. A chromogenic anti-FXa assay can be used for reliable measurements of apixaban concentration. © 2014 International Society on Thrombosis and Haemostasis.

  20. Re-Initiation of Dabigatran and Direct Factor Xa Antagonists After a Major Bleed

    PubMed Central

    Milling, Truman J.; Spyropoulos, Alex C.

    2017-01-01

    Direct oral anticoagulants (DOACs) are a relatively recent addition to the oral anticoagulant armamentarium, and provide an alternative to the use of vitamin K antagonists such as warfarin. Regardless of the type of agent used, bleeding is the major complication of anticoagulant therapy. The decision to restart oral anticoagulation following a major hemorrhage in a previously anticoagulated patient is supported largely by retrospective studies rather than randomized clinical trials (mostly with vitamin K antagonists), and remains an issue of individualized clinical assessment: the patient’s risk of thromboembolism must be balanced with the risk of recurrent major bleeding. This review provides guidance for clinicians regarding if and when a patient should be re-initiated on DOAC therapy following a major hemorrhage, based on the existing evidence. PMID:27569671

  1. Phenyltriazolinones as potent factor Xa inhibitors.

    PubMed

    Quan, Mimi L; Pinto, Donald J P; Rossi, Karen A; Sheriff, Steven; Alexander, Richard S; Amparo, Eugene; Kish, Kevin; Knabb, Robert M; Luettgen, Joseph M; Morin, Paul; Smallwood, Angela; Woerner, Francis J; Wexler, Ruth R

    2010-02-15

    We have discovered that phenyltriazolinone is a novel and potent P1 moiety for coagulation factor Xa. X-ray structures of the inhibitors with a phenyltriazolinone in the P1 position revealed that the side chain of Asp189 has reoriented resulting in a novel S1 binding pocket which is larger in size to accommodate the phenyltriazolinone P1 substrate.

  2. Computational investigation of potential dosing schedules for a switch of medication from warfarin to rivaroxaban—an oral, direct Factor Xa inhibitor

    PubMed Central

    Burghaus, Rolf; Coboeken, Katrin; Gaub, Thomas; Niederalt, Christoph; Sensse, Anke; Siegmund, Hans-Ulrich; Weiss, Wolfgang; Mueck, Wolfgang; Tanigawa, Takahiko; Lippert, Jörg

    2014-01-01

    The long-lasting anticoagulant effect of vitamin K antagonists can be problematic in cases of adverse drug reactions or when patients are switched to another anticoagulant therapy. The objective of this study was to examine in silico the anticoagulant effect of rivaroxaban, an oral, direct Factor Xa inhibitor, combined with the residual effect of discontinued warfarin. Our simulations were based on the recommended anticoagulant dosing regimen for stroke prevention in patients with atrial fibrillation. The effects of the combination of discontinued warfarin plus rivaroxaban were simulated using an extended version of a previously validated blood coagulation computer model. A strong synergistic effect of the two distinct mechanisms of action was observed in the first 2–3 days after warfarin discontinuation; thereafter, the effect was close to additive. Nomograms for the introduction of rivaroxaban therapy after warfarin discontinuation were derived for Caucasian and Japanese patients using safety and efficacy criteria described previously, together with the coagulation model. The findings of our study provide a mechanistic pharmacologic rationale for dosing schedules during the therapy switch from warfarin to rivaroxaban and support the switching strategies as outlined in the Summary of Product Characteristics and Prescribing Information for rivaroxaban. PMID:25426077

  3. Global coagulation tests: their applicability for measuring direct factor Xa- and thrombin inhibition and reversal of anticoagulation by prothrombin complex concentrate.

    PubMed

    Dinkelaar, Jasper; Patiwael, Sanne; Harenberg, Job; Leyte, Anja; Brinkman, Herm Jan M

    2014-11-01

    Specific mass spectrometry and direct activated factor X (Xa)- and thrombin inhibition assays do not allow determination of the reversal of anticoagulant effects of non-vitamin K direct oral anticoagulants (NOACs) by prothrombin complex concentrate (PCC). The objective of this study was the evaluation of the applicability of a variety of commercially available global coagulation assays in analyzing the reversal of NOAC anticoagulation by PCC. Plasma and whole blood were spiked with apixaban or dabigatran and PCC was added to these samples. Prothrombin time (PT), modified PT (mPT), activated partial prothrombin time (APTT), thrombography (CAT method) and thromboelastography (ROTEM, TEG) were performed. Assays triggered by contact activation (APTT, INTEM) did not show inhibitor reversal by PCC. Assays triggered by tissue factor (TF) showed NOAC type and NOAC concentration dependent anticoagulation reversal effects of PCC ranging from partial normalization to overcorrection of the following parameters: clotting or reaction time (PT, mPT TEG-TF, EXTEM, FIBTEM); angle in thromboelastography (TEG-TF); thrombin generation (CAT) lag time, endogenous thrombin potential (ETP) and peak thrombin. Extent of reversal was assay reagent dependent. ETP (5 pM TF) was the only parameter showing complete reversal of anticoagulation by PCC for all NOACs ranging from 200 to 800 μg/L. ETP fits with the concept that reversal assessment of NOAC anticoagulation by PCC should be based on measurements on the clotting potential or thrombin generating potential of the plasma or whole blood patient sample. Low sensitivity of ETP for NOACs and its correlation with bleeding are issues that remain to be resolved.

  4. Factor Xa: Simulation studies with an eye to inhibitor design

    NASA Astrophysics Data System (ADS)

    Daura, Xavier; Haaksma, Eric; van Gunsteren, Wilfred F.

    2000-08-01

    Factor Xa is a serine protease which activates thrombin and plays a key regulatory role in the blood-coagulation cascade. Factor Xa is at the crossroads of the extrinsic and intrinsic pathways of coagulation and, hence, has become an important target for the design of anti-thrombotics (inhibitors). It is not known to be involved in other processes than hemostasis and its binding site is different to that of other serine proteases, thus facilitating selective inhibition. The design of high-affinity selective inhibitors of factor Xa requires knowledge of the structural and dynamical characteristics of its active site. The three-dimensional structure of factor Xa was resolved by X-ray crystallography and refined at 2.2 Å resolution by Padmanabhan and collaborators. In this article we present results from molecular dynamics simulations of the catalytic domain of factor Xa in aqueous solution. The simulations were performed to characterise the mobility and flexibility of the residues delimiting the unoccupied binding site of the enzyme, and to determine hydrogen bonding propensities (with protein and with solvent atoms) of those residues in the active site that could interact with a substrate or a potential inhibitor. The simulation data is aimed at facilitating the design of high-affinity selective inhibitors of factor Xa.

  5. The effect of the direct factor Xa inhibitors apixaban and rivaroxaban on haemostasis tests: a comprehensive assessment using in vitro and ex vivo samples.

    PubMed

    Bonar, Roslyn; Favaloro, Emmanuel J; Mohammed, Soma; Ahuja, Monica; Pasalic, Leonardo; Sioufi, John; Marsden, Katherine

    2016-01-01

    The direct oral anticoagulants (DOACs), now including dabigatran, apixaban and rivaroxaban, have given clinicians alternative options to low molecular weight heparins (LMWHs) and vitamin K antagonist therapy, including warfarin, for the treatment of atrial fibrillation and treatment and prevention of venous thromboembolic (VTE) disease. DOACs have been successfully marketed as not requiring monitoring; however, there will be situations where clinicians will request laboratory testing, including emergency department admissions for haemorrhage or thrombosis, or emergency surgical interventions. We report the results of several Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) surveys using apixaban and rivaroxaban spiked samples to either assess the suitability of certain potential screening or drug-quantifying assays, for assessment of drug presence or absence or measurement of levels, as well as assessing potential interference in a wide variety of haemostasis assays. We also include additional evaluations using ex vivo samples from patients given apixaban and rivaroxaban for various therapeutic reasons. The prothrombin time (PT) and activated partial thromboplastin time (APTT) show better sensitivity with rivaroxaban than apixaban. Anti-Xa assays show good concordance and reproducibility with expected drug levels; however, availability of these assays may be limited to larger institutions. Interference of apixaban and rivaroxaban on haemostasis testing extends beyond routine coagulation assays to encompass a plethora of specialised assays, including factor assays, lupus inhibitor, and FVIII inhibitor estimation. In conclusion, this report highlights the influence of these drugs on most tests performed in haemostasis laboratories, and the potential for some tests to predict the presence, absence or level of these drugs in plasma.

  6. Heparin chain-length dependence of factor Xa inhibition by antithrombin in plasma.

    PubMed

    Rezaie, Alireza R

    2007-01-01

    Heparin anticoagulants function by enhancing the inhibition of coagulation proteases by the serpin antithrombin (AT). A direct evaluation of the specific anti-factor Xa (fXa) activity of therapeutic heparins in the physiologically relevant plasma-based clotting assays has not been feasible since thrombin, the final protease of the cascade, is the primary target for inhibition by AT in the presence of heparin. To circumvent this problem, we developed an assay in which the native AT in plasma was replaced with an AT mutant which exhibits identical affinity for heparin and near normal reactivity for fXa, but does not react with thrombin and other coagulation proteases in either the absence or presence of heparin. This assay was used to distinguish the anti-fXa activity of different molecular weight heparins from their anti-thrombin activity in clotting assays which were initiated by the triggers of either the extrinsic or intrinsic coagulation pathway. The results suggest that the acceleration of fXa inhibition by AT exhibits a marked heparin chain-length dependence, with fondaparinux (a pentasaccharide) having the lowest and unfractionated heparin having the highest effect. Interestingly, comparative studies revealed that the fondaparinux-catalyzed acceleration of thrombin inhibition by AT also contributes to the prolongation of the clotting time, possibly suggesting that the anticoagulant function of the therapeutic pentasaccharide is mediated though the inhibition of both fXa and thrombin.

  7. Comparative evaluation of direct thrombin and factor Xa inhibitors with antiplatelet agents under flow and static conditions: an in vitro flow chamber model.

    PubMed

    Hosokawa, Kazuya; Ohnishi, Tomoko; Sameshima, Hisayo; Miura, Naoki; Koide, Takehiko; Maruyama, Ikuro; Tanaka, Kenichi A

    2014-01-01

    Dabigatran and rivaroxaban are novel oral anticoagulants that specifically inhibit thrombin and factor Xa, respectively. The aim of this study is to elucidate antithrombotic properties of these anticoagulant agents under arterial and venous shear conditions. Whole blood samples treated with dabigatran or rivaroxaban at 250, 500, and 1000 nM, with/without aspirin and AR-C66096, a P2Y12 antagonist, were perfused over a microchip coated with collagen and tissue thromboplastin at shear rates of 240 and 600 s(-1). Fibrin-rich platelet thrombus formation was quantified by monitoring flow pressure changes. Dabigatran at higher concentrations (500 and 1000 nM) potently inhibited thrombus formation at both shear rates, whereas 1000 nM of rivaroxaban delayed, but did not completely inhibit, thrombus formation. Dual antiplatelet agents weakly suppressed thrombus formation at both shear rates, but intensified the anticoagulant effects of dabigatran and rivaroxaban. The anticoagulant effects of dabigatran and rivaroxaban were also evaluated under static conditions using thrombin generation (TG) assay. In platelet-poor plasma, dabigatran at 250 and 500 nM efficiently prolonged the lag time (LT) and moderately reduce peak height (PH) of TG, whereas rivaroxaban at 250 nM efficiently prolonged LT and reduced PH of TG. In platelet-rich plasma, however, both anticoagulants efficiently delayed LT and reduced PH of TG. Our results suggest that dabigatran and rivaroxaban may exert distinct antithrombotic effects under flow conditions, particularly in combination with dual antiplatelet therapy.

  8. Comparative Evaluation of Direct Thrombin and Factor Xa Inhibitors with Antiplatelet Agents under Flow and Static Conditions: An In Vitro Flow Chamber Model

    PubMed Central

    Hosokawa, Kazuya; Ohnishi, Tomoko; Sameshima, Hisayo; Miura, Naoki; Koide, Takehiko; Maruyama, Ikuro; Tanaka, Kenichi A.

    2014-01-01

    Dabigatran and rivaroxaban are novel oral anticoagulants that specifically inhibit thrombin and factor Xa, respectively. The aim of this study is to elucidate antithrombotic properties of these anticoagulant agents under arterial and venous shear conditions. Whole blood samples treated with dabigatran or rivaroxaban at 250, 500, and 1000 nM, with/without aspirin and AR-C66096, a P2Y12 antagonist, were perfused over a microchip coated with collagen and tissue thromboplastin at shear rates of 240 and 600 s−1. Fibrin-rich platelet thrombus formation was quantified by monitoring flow pressure changes. Dabigatran at higher concentrations (500 and 1000 nM) potently inhibited thrombus formation at both shear rates, whereas 1000 nM of rivaroxaban delayed, but did not completely inhibit, thrombus formation. Dual antiplatelet agents weakly suppressed thrombus formation at both shear rates, but intensified the anticoagulant effects of dabigatran and rivaroxaban. The anticoagulant effects of dabigatran and rivaroxaban were also evaluated under static conditions using thrombin generation (TG) assay. In platelet-poor plasma, dabigatran at 250 and 500 nM efficiently prolonged the lag time (LT) and moderately reduce peak height (PH) of TG, whereas rivaroxaban at 250 nM efficiently prolonged LT and reduced PH of TG. In platelet-rich plasma, however, both anticoagulants efficiently delayed LT and reduced PH of TG. Our results suggest that dabigatran and rivaroxaban may exert distinct antithrombotic effects under flow conditions, particularly in combination with dual antiplatelet therapy. PMID:24497951

  9. Rivaroxaban, a direct inhibitor of the coagulation factor Xa interferes with hormonal-induced physiological modulations in human female osteoblastic cell line SaSO2.

    PubMed

    Somjen, Dalia; Katzburg, Sara; Gigi, Roi; Dolkart, Oleg; Sharon, Orli; Salai, Moshe; Stern, Naftali

    2013-05-01

    The use of anticoagulants has been associated with systemic osteoporosis and increased risk for poor fracture healing but is inevitable following major orthopedic surgery of lower limbs. Rivaroxaban A (R) is an anticoagulant recently introduced in the clinical setting, which is a specific factor Xa inhibitor. We reported previously that R significantly inhibited cell growth, energy metabolism and alkaline phosphatase activity in human osteoblastic cell line SaOS2, with no effect on mineralization, indicating transient inhibition of bone formation. We now investigated the effects of R on SaOS2 response to osteoblast-modulating hormones. At sub-confluence cells were treated with: estradiol-17β (E2), the phytoestrogens daidzein (D) and biochainin A (BA), the carboxy-pytoestrogenic derivative carboxy-D (cD), the estrogen receptor α (ERα) agonist PPT, the estrogen receptor β (ERβ) agonist DPN, parathyroid hormone (PTH) and several vitamin D metabolites and analogs with/without R for 24h. All hormones tested stimulated significantly DNA synthesis (DNA), creatine kinase (CK) and alkaline phosphatase (ALP) specific activities, but all these stimulations were totally inhibited when given together with R. R had no effect on mRNA expression of ERα, ERβ and 25 Hydroxy-vitamin D3-1α hydroxylase (1OHase), but inhibited hormonal modulations of mRNA expressions. In conclusion R inhibited significantly hormonal stimulation of different parameters indicating inhibition of not only the early stages of bone formation, but also the stimulatory effects of bone modulating hormones with a yet unclear mechanism. The relevance of these findings to human bone physiology is yet to be investigated.

  10. Kinetic characterization of factor Xa binding using a quenched fluorescent substrate based on the reactive site of factor Xa inhibitor from Bauhinia ungulata seeds.

    PubMed

    Oliva, M L V; Andrade, S A; Juliano, M A; Sallai, R C; Torquato, R J; Sampaio, M U; Pott, V J; Sampaio, C A M

    2003-07-01

    The specific Kunitz Bauhinia ungulata factor Xa inhibitor (BuXI) and the Bauhinia variegata trypsin inhibitor (BvTI) blocked the activity of trypsin, chymotrypsin, plasmin, plasma kallikrein and factor XIIa, and factor Xa inhibition was achieved only by BuXI (K(i) 14 nM). BuXI and BvTI are highly homologous (70%). The major differences are the methionine residues at BuXI reactive site, which are involved in the inhibition, since the oxidized protein no longer inhibits factor Xa but maintains the trypsin inhibition. Quenched fluorescent substrates based on the reactive site sequence of the inhibitors were synthesized and the kinetic parameters of the hydrolysis were determined using factor Xa and trypsin. The catalytic efficiency k(cat)/K(m) 4.3 x 10(7) M(-1)sec(>-1) for Abz-VMIAALPRTMFIQ-EDDnp (lead peptide) hydrolysis by factor Xa was 10(4)-fold higher than that of Boc-Ile-Glu-Gly-Arg-AMC, widely used as factor Xa substrate. Lengthening of the substrate changed its susceptibility to factor Xa hydrolysis. Both methionine residues in the substrate influence the binding to factor Xa. Serine replacement of threonine (P(1)') decreases the catalytic efficiency by four orders of magnitude. Factor Xa did not hydrolyze the substrate containing the reactive site sequence of BvTI, that inhibits trypsin inhibitor but not factor Xa. Abz-VMIAALPRTMFIQ-EDDnp prolonged both the prothrombin time and the activated partial thromboplastin time, and the other modified substrates used in this experiment altered blood-clotting assays.

  11. Factors associated with major bleeding events: insights from the ROCKET AF trial (rivaroxaban once-daily oral direct factor Xa inhibition compared with vitamin K antagonism for prevention of stroke and embolism trial in atrial fibrillation).

    PubMed

    Goodman, Shaun G; Wojdyla, Daniel M; Piccini, Jonathan P; White, Harvey D; Paolini, John F; Nessel, Christopher C; Berkowitz, Scott D; Mahaffey, Kenneth W; Patel, Manesh R; Sherwood, Matthew W; Becker, Richard C; Halperin, Jonathan L; Hacke, Werner; Singer, Daniel E; Hankey, Graeme J; Breithardt, Gunter; Fox, Keith A A; Califf, Robert M

    2014-03-11

    This study sought to report additional safety results from the ROCKET AF (Rivaroxaban Once-daily oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation). The ROCKET AF trial demonstrated similar risks of stroke/systemic embolism and major/nonmajor clinically relevant bleeding (principal safety endpoint) with rivaroxaban and warfarin. The risk of the principal safety and component bleeding endpoints with rivaroxaban versus warfarin were compared, and factors associated with major bleeding were examined in a multivariable model. The principal safety endpoint was similar in the rivaroxaban and warfarin groups (14.9 vs. 14.5 events/100 patient-years; hazard ratio: 1.03; 95% confidence interval: 0.96 to 1.11). Major bleeding risk increased with age, but there were no differences between treatments in each age category (<65, 65 to 74, ≥75 years; pinteraction = 0.59). Compared with those without (n = 13,455), patients with a major bleed (n = 781) were more likely to be older, current/prior smokers, have prior gastrointestinal (GI) bleeding, mild anemia, and a lower calculated creatinine clearance and less likely to be female or have a prior stroke/transient ischemic attack. Increasing age, baseline diastolic blood pressure (DBP) ≥90 mm Hg, history of chronic obstructive pulmonary disease or GI bleeding, prior acetylsalicylic acid use, and anemia were independently associated with major bleeding risk; female sex and DBP <90 mm Hg were associated with a decreased risk. Rivaroxaban and warfarin had similar risk for major/nonmajor clinically relevant bleeding. Age, sex, DBP, prior GI bleeding, prior acetylsalicylic acid use, and anemia were associated with the risk of major bleeding. (An Efficacy and Safety Study of Rivaroxaban With Warfarin for the Prevention of Stroke and Non-Central Nervous System Systemic Embolism in Patients With Non-Valvular Atrial Fibrillation: NCT00403767

  12. Factor Xa stimulates fibroblast procollagen production, proliferation, and calcium signaling via PAR{sub 1} activation

    SciTech Connect

    Blanc-Brude, Olivier P. . E-mail: olivier.blanc-brude@larib.inserm.fr; Archer, Fabienne; Leoni, Patricia; Derian, Claudia; Bolsover, Steven; Laurent, Geoffrey J.; Chambers, Rachel C.

    2005-03-10

    Fibroblast proliferation and procollagen production are central features of tissue repair and fibrosis. In addition to its role in blood clotting, the coagulation cascade proteinase thrombin can contribute to tissue repair by stimulating fibroblasts via proteolytic activation of proteinase-activated receptor-1 (PAR{sub 1}). During hemostasis, the coagulation cascade proteinase factor X is converted into factor Xa. We have previously shown that factor Xa upregulates fibroblast proliferation via production of autocrine PDGF. In this study, we further examined the effects of factor Xa on fibroblast function and aimed to identify its signaling receptor. We showed that factor Xa stimulates procollagen promoter activity and protein production by human and mouse fibroblasts. This effect was independent of PDGF and thrombin production, but dependent on factor Xa proteolytic activity. We also showed that PAR{sub 1}-deficient mouse fibroblasts did not upregulate procollagen production, mobilize cytosolic calcium, or proliferate in response to factor Xa. Desensitization techniques and PAR{sub 1}-specific agonists and inhibitors were used to demonstrate that PAR{sub 1} mediates factor Xa signaling in human fibroblasts. This is the first report that factor Xa stimulates extracellular matrix production. In contrast with endothelial cells and vascular smooth muscle cells, fibroblasts appear to be the only cell type in which the effects of factor Xa are mediated mainly via PAR{sub 1} and not PAR{sub 2}. These findings are critical for our understanding of tissue repair and fibrotic mechanisms, and for the design of novel approaches to inhibit the profibrotic effects of the coagulation cascade without compromising blood hemostasis.

  13. New advances in the discovery of thrombin and factor Xa inhibitors.

    PubMed

    Vacca, J P

    2000-08-01

    The search for the ideal anticoagulant has spanned decades and has resulted in several strategies including the clinical use of heparin, low molecular weight heparins, and the vitamin K antagonist warfarin. Over the past five years, many groups have reported preclinical results with direct-acting thrombin inhibitors and several of these are now moving into clinical trials. In addition, many groups have disclosed the discovery of potent, orally bioavailable factor Xa inhibitors. Several of these compounds are now in early clinical trials and the results are forthcoming.

  14. [Management of major bleeding complications and emergency surgery in patients on long-term treatment with direct oral anticoagulants, thrombin or factor-Xa inhibitors. Proposals of the Working Group on Perioperative Haemostasis (GIHP) - March 2013].

    PubMed

    Pernod, G; Albaladejo, P; Godier, A; Samama, C M; Susen, S; Gruel, Y; Blais, N; Fontana, P; Cohen, A; Llau, J V; Rosencher, N; Schved, J F; de Maistre, E; Samama, M M; Mismetti, P; Sié, P

    2013-10-01

    New direct oral anticoagulants (NOAC), inhibitors of factor IIa or Xa, are expected to be widely used for the treatment of venous thromboembolic disease, or in case of atrial fibrillation. Such anticoagulant treatments are known to be associated with haemorrhagic complications. Moreover, it is likely that such patients on long-term treatment with NOAC will be exposed to emergency surgery or invasive procedures. Due to the present lack of experience in such conditions, we cannot make recommendations, but only propose management for optimal safety as regards the risk of bleeding in such emergency conditions. In this article, only dabigatran and rivaroxaban were discussed. For emergency surgery at risk of bleeding, we propose to dose the plasmatic concentration of drug. Levels inferior or equal to 30ng/mL for both dabigatran and rivaroxaban, should enable the realization of a high bleeding risk surgery. For higher concentration, it was proposed to postpone surgery by monitoring the evolution of the drug concentration. Action is then defined by the kind of NOAC and its concentration. If the dosage of the drug is not immediately available, proposals only based on the usual tests, PT and aPTT, also are presented. However, these tests do not really assess drug concentration or bleeding risk. In case of severe haemorrhage in a critical organ, it is proposed to reduce the effect of anticoagulant therapy using a nonspecific procoagulant drug (activated prothrombin concentrate, FEIBA, 30-50U/kg, or non-activated 4-factors prothrombin concentrates 50U/kg). For any other type of severe haemorrhage, the administration of such a procoagulant drug, potentially thrombogenic in these patients, will be discussed regarding concentration of NACO and possibilities for mechanical haemostasis.

  15. Design of novel aminopyrrolidine factor Xa inhibitors from a screening hit.

    PubMed

    Zbinden, Katrin Groebke; Anselm, Lilli; Banner, David W; Benz, Jörg; Blasco, Francesca; Décoret, Guillaume; Himber, Jacques; Kuhn, Bernd; Panday, Narendra; Ricklin, Fabienne; Risch, Philippe; Schlatter, Daniel; Stahl, Martin; Thomi, Stefan; Unger, Robert; Haap, Wolfgang

    2009-07-01

    Starting from a hit identified by focused screening, 3-aminopyrrolidine factor Xa inhibitors were designed. The binding mode as determined by X-ray structural analysis as well as the pharmacokinetic behaviour of selected compounds is discussed.

  16. Management of major bleeding complications and emergency surgery in patients on long-term treatment with direct oral anticoagulants, thrombin or factor-Xa inhibitors: proposals of the working group on perioperative haemostasis (GIHP) - March 2013.

    PubMed

    Pernod, Gilles; Albaladejo, Pierre; Godier, Anne; Samama, Charles M; Susen, Sophie; Gruel, Yves; Blais, Normand; Fontana, Pierre; Cohen, Ariel; Llau, Juan V; Rosencher, Nadia; Schved, Jean-François; de Maistre, Emmanuel; Samama, Meyer M; Mismetti, Patrick; Sié, Pierre

    2013-01-01

    Direct new oral anticoagulants (NOACs) - inhibitors of thrombin or factor Xa - are intended to be used largely in the treatment of venous thromboembolic disease or the prevention of systematic embolism in atrial fibrillation, instead of vitamin K antagonists. Like any anticoagulant treatment, they are associated with spontaneous or provoked haemorrhagic risk. Furthermore, a significant proportion of treated patients are likely to be exposed to emergency surgery or invasive procedures. Given the absence of a specific antidote, the action to be taken in these situations must be defined. The lack of data means that it is only possible to issue proposals rather than recommendations, which will evolve according to accumulated experience. The proposals presented here apply to dabigatran (Pradaxa(®)) and rivaroxaban (Xarelto(®)); data for apixaban and edoxaban are still scarce. For urgent surgery with haemorrhagic risk, the drug plasma concentration should be less or equal to 30ng/mL for dabigatran and rivaroxaban should enable surgery associated with a high bleeding risk. Beyond that, if possible, the intervention should be postponed by monitoring the drug concentration. The course to follow is then defined according to the NOAC and its concentration. If the anticoagulant dosage is not immediately available, worse propositions, based on the usual tests (prothrombin time and activated partial thromboplastin time), are presented. However, these tests do not really assess drug concentration or the risk of bleeding that depends on it. In case of serious bleeding in a critical organ, the effect of anticoagulant therapy should be reduced using a non-specific procoagulant drug as a first-line approach: activated prothrombin complex concentrate (aPCC) (FEIBA(®) 30-50U/kg) or non-activated PCC (50U/kg). In addition, for any other type of severe haemorrhage, the administration of a procoagulant drug, which is potentially thrombogenic in these patients, is discussed according

  17. The cost-effectiveness of oral direct factor Xa inhibitors compared with low-molecular-weight heparin for the prevention of venous thromboembolism prophylaxis in total hip or knee replacement surgery.

    PubMed

    Mahmoudi, Mandana; Sobieraj, Diana M

    2013-12-01

    Major orthopedic surgery is associated with a high risk of venous thromboembolism (VTE). Anticoagulants are recommended to prevent VTE, and recently an oral direct factor Xa inhibitor (FXaI) was approved for this indication. We compared the cost-effectiveness of FXaIs with low-molecular-weight heparin (LMWH) in patients undergoing total hip replacement (THR) or total knee replacement (TKR) surgery. A decision-tree model was developed to compare the cost-effectiveness of oral direct FXaIs (rivaroxaban, apixaban, and edoxaban) to subcutaneous LMWHs (enoxaparin and dalteparin), with separate models for THR and TKR. The analysis was conducted over a 180-day postoperative time horizon from the U.S. Medicare perspective. The model was developed using TreeAge Pro 2011 (TreeAge Software Inc., Williamstown, MA, USA). Efficacy and safety data (probabilities of distal and proximal deep vein thrombosis, symptomatic pulmonary embolism, and major bleeding) were derived from a systematic review and meta-analysis of phase II and III clinical trials. Costs and quality-adjusted life-years (QALYs) are reported. One-way and probabilistic sensitivity analyses were performed to evaluate parameter uncertainty. In the THR model, the average costs per patient for FXaIs and LMWHs were $18,762 and $18,897, respectively, and the QALYs were 0.938 and 0.932. In the TKR model, the average cost per patient for FXaIs and LMWHs were $18,804 and $18,991, respectively, and the QALYs were 0.935 and 0.931. In both models, FXaIs dominated LMWH (less costly and more efficacious). Neither model was sensitive to changes in any of the variables in the one-way sensitivity analyses. Probabilistic sensitivity analysis indicated that FXaIs were cost-effective in more than 99% of iterations in the THR population and in 98% of iterations in the TKR population assuming a willingness-to-pay threshold of $50,000/QALY. Oral direct FXaIs may be an economically dominant strategy compared with LMWHs for VTE prophylaxis

  18. Kinetic characterization of the protein Z-dependent protease inhibitor reaction with blood coagulation factor Xa.

    PubMed

    Huang, Xin; Swanson, Richard; Broze, George J; Olson, Steven T

    2008-10-31

    Protein Z-dependent protease inhibitor (ZPI) is a recently identified member of the serpin superfamily that functions as a cofactor-dependent regulator of blood coagulation factors Xa (FXa) and XIa. Here we show that ZPI and its cofactor, protein Z (PZ), inhibit procoagulant membrane-bound factor Xa by the branched pathway acyl-intermediate trapping mechanism used by other serpins, but with significant variations of this mechanism that are unique to ZPI. Rapid kinetic analyses showed that the reaction proceeded by the initial assembly of a membrane-associated PZ-ZPI-FXa Michaelis complex (K(M) 53+/-5 nM) followed by conversion to a stable ZPI-FXa complex (k(lim) 1.2+/-0.1 s(-1)). Cofactor premixing experiments together with independent kinetic analyses of ZPI-PZ and factor Xa-PZ-membrane complex formation suggested that assembly of the Michaelis complex through either ZPI-PZ-lipid or factor Xa-PZ-lipid intermediates was rate-limiting. Reaction stoichiometry analyses and native PAGE showed that for every factor Xa molecule inhibited by ZPI, two serpin molecules were cleaved. Native PAGE and immunoblotting showed that PZ dissociated from ZPI once ZPI forms a stable complex with FXa, and kinetic analyses confirmed that PZ acted catalytically to accelerate the membrane-dependent ZPI-factor Xa reaction. The ZPI-FXa complex was only transiently stable and dissociated with a rate constant that showed a bell-shaped pH dependence indicative of participation of factor Xa active-site residues. The complex was detectable by SDS-PAGE when denatured at low pH, consistent with it being a kinetically trapped covalent acyl-intermediate. Together our findings show that ZPI functions like other serpins to regulate the activity of FXa but in a manner uniquely dependent on protein Z, procoagulant membranes, and pH.

  19. Anti-xa directed protocol for anticoagulation management in children supported with extracorporeal membrane oxygenation.

    PubMed

    O'Meara, L Carlisle; Alten, Jeffrey A; Goldberg, Kellen G; Timpa, Joseph G; Phillips, Jay; Laney, Debbie; Borasino, Santiago

    2015-01-01

    The optimum heparin monitoring method during extracorporeal membrane oxygenation (ECMO) is unknown. We report a protocol utilizing only anti-factor Xa (anti-Xa) to manage anticoagulation in 22 consecutive ECMO patients. Anti-Xa was monitored with heparin titration every hour until goal 0.4-0.8 IU/ml. Once therapeutic, monitoring was progressively spaced up to every 6 hours. Patients received frequent antithrombin III (ATIII). Extracorporeal membrane oxygenation indications were as follows: 13 cardiorespiratory failures, eight extracorporeal cardiopulmonary resuscitations (ECPRs), and one pulmonary hypertension. Median weight was 4 kg, age 12.5 days, and ECMO duration 88 hours. Survival was 50%. Mean heparin dose was 38 ± 11 unit/kg/hr. Eight patients received no heparin for median 9 hours because of postoperative bleeding. Compared with prior activated clotting time (ACT) protocol, there were 20 fewer blood draws per day to manage anticoagulation, p < 0.001. Only 9% of the anti-Xa levels were outside therapeutic range versus 22% using ACT, p < 0.01. Six patients had bleeding complications, and seven had oxygenator change-out. Change-out was associated with blood product administration and bleeding but not with heparin-free period (p = 0.39). Survival to discharge was higher among those who did not require circuit/oxygenator change-outs, 4/7 versus 7/7 (p < 0.01). Anti-factor Xa-based ECMO heparin management protocol is feasible, decreases blood sampling and heparin infusion adjustments, and does not appear to increase complications.

  20. Apixaban, an oral, direct, selective factor Xa inhibitor, in combination with antiplatelet therapy after acute coronary syndrome: results of the Apixaban for Prevention of Acute Ischemic and Safety Events (APPRAISE) trial.

    PubMed

    Alexander, John H; Becker, Richard C; Bhatt, Deepak L; Cools, Frank; Crea, Filippo; Dellborg, Mikael; Fox, Keith A A; Goodman, Shaun G; Harrington, Robert A; Huber, Kurt; Husted, Steen; Lewis, Basil S; Lopez-Sendon, Jose; Mohan, Puneet; Montalescot, Gilles; Ruda, Mikhail; Ruzyllo, Witold; Verheugt, Freek; Wallentin, Lars

    2009-06-09

    After an acute coronary syndrome, patients remain at risk of recurrent events. Apixaban, an oral direct factor Xa inhibitor, is a novel anticoagulant that may reduce these events but also poses a risk of bleeding. Apixaban for Prevention of Acute Ischemic and Safety Events (APPRAISE) was a phase 2, double-blind, placebo-controlled, dose-ranging study. Patients (n=1715) with recent ST-elevation or non-ST-elevation acute coronary syndrome were randomized to 6 months of placebo (n=611) or 1 of 4 doses of apixaban: 2.5 mg twice daily (n=317), 10 mg once daily (n=318), 10 mg twice daily (n=248), or 20 mg once daily (n=221). Nearly all patients received aspirin; 76% received clopidogrel. The primary outcome was International Society of Thrombosis and Hemostasis major or clinically relevant nonmajor bleeding. A secondary outcome was cardiovascular death, myocardial infarction, severe recurrent ischemia, or ischemic stroke. At the recommendation of the Data Monitoring Committee, the 2 higher-dose apixaban arms were discontinued because of excess total bleeding. Compared with placebo, apixaban 2.5 mg twice daily (hazard ratio, 1.78; 95% confidence interval, 0.91 to 3.48; P=0.09) and 10 mg once daily (hazard ratio, 2.45; 95% confidence interval, 1.31 to 4.61; P=0.005) resulted in a dose-dependent increase in major or clinically relevant nonmajor bleeding. Apixaban 2.5 mg twice daily (hazard ratio, 0.73; 95% confidence interval, 0.44 to 1.19; P=0.21) and 10 mg once daily (hazard ratio, 0.61; 95% confidence interval, 0.35 to 1.04; P=0.07) resulted in lower rates of ischemic events compared with placebo. The increase in bleeding was more pronounced and the reduction in ischemic events was less evident in patients taking aspirin plus clopidogrel than in those taking aspirin alone. We observed a dose-related increase in bleeding and a trend toward a reduction in ischemic events with the addition of apixaban to antiplatelet therapy in patients with recent acute coronary syndrome

  1. Role of Factor Xa Inhibitors in Cancer-Associated Thrombosis: Any New Data?

    PubMed Central

    Zalpour, Ali; Kroll, Michael H.; Afshar-Kharghan, Vahid; Yusuf, Syed Wamique; Escalante, Carmen

    2011-01-01

    The association between cancer and venous thromboembolism (VTE) has been well documented in the literature. Prevention and treatment of VTE in cancer patients is imperative. Typically, the mainstay regimen for VTE prevention and treatment has been anticoagulation therapy, unless contraindicated. This therapy consists of unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), factor Xa inhibitor, or vitamin K antagonist (VKA). Current guidelines recommend LMWH over VKA for the treatment of VTE in cancer patients. Factor-specific anticoagulants have been proven safe and effective, and recently factor Xa inhibitors have emerged as a treatment alternative to heparins and VKA. Currently, three factor Xa inhibitors have been identified: fondaparinux (the only one approved so far by the US Food and Drug Administration), idraparinux (in clinical trials), and idrabiotaparinux (in clinical trials). This paper will examine the role of these agents, focusing on fondaparinux, for the prevention and treatment of VTE in cancer patients. PMID:22013445

  2. Venous Thromboembolism Prophylaxis After TKA: Aspirin, Warfarin, Enoxaparin, or Factor Xa Inhibitors?

    PubMed

    Bala, Abiram; Huddleston, James I; Goodman, Stuart B; Maloney, William J; Amanatullah, Derek F

    2017-09-01

    There is considerable debate regarding the ideal agent for venous thromboembolism (VTE) prophylaxis after TKA. Numerous studies and meta-analyses have yet to provide a clear answer and often omit one or more of the commonly used agents such as aspirin, warfarin, enoxaparin, and factor Xa inhibitors. Using a large database analysis, we asked: (1) What are the differences in VTE incidence in primary TKA after administration of aspirin, warfarin, enoxaparin, or factor Xa inhibitors? (2) What are the differences in bleeding risk among these four agents? (3) How has use of these agents changed with time? We queried a combined Humana and Medicare database between 2007 and Quarter 1 of 2016, and identified all primary TKAs performed using ICD-9 and Current Procedural Terminology codes. All patients who had any form of antiplatelet or anticoagulation prescribed within 1 year before TKA were excluded from our study cohort. We then identified patients who had either aspirin, warfarin, enoxaparin, or factor Xa inhibitors prescribed within 2 weeks of primary TKA. Each cohort was matched by age and sex. Elixhauser comorbidities and Charlson Comorbidity Index for each group were calculated. We identified 1016 patients with aspirin, and age- and sex-matched 6096 patients with enoxaparin, 6096 patients with warfarin, and 5080 patients with factor Xa inhibitors. Using ICD-9 codes, with the understanding that patients at greater risk may have had more-attentive surveillance, the incidence of postoperative deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding-related complications (bleeding requiring surgical intervention, hemorrhage, hematoma, hemarthrosis), postoperative anemia, and transfusion were identified at 2 weeks, 30 days, 6 weeks, and 90 days postoperatively. A four-way chi-squared test was used to determine statistical significance. Utilization was calculated using compound annual growth rate. There was a difference in the incidence of DVT at 90 days (p < 0

  3. Specificity and selectivity profile of EP217609: a new neutralizable dual-action anticoagulant that targets thrombin and factor Xa

    PubMed Central

    Swanson, Richard; Petitou, Maurice

    2012-01-01

    EP217609 is a new dual-action parenteral anticoagulant that combines an indirect factor Xa inhibitor (fondaparinux analog) and a direct thrombin inhibitor (α-NAPAP analog) in a single molecule together with a biotin tag to allow avidin neutralization. EP217609 exhibits an unprecedented pharmacologic profile in showing high bioavailability, long plasma half-life, and potent antithrombotic activity in animals without the complications of thrombin rebound. Here we report the exceptional specificity and selectivity profile of EP217609. EP217609 inhibited thrombin with rapid kinetics (kon > 107M−1s−1), a high affinity (KI = 30-40pM), and more than 1000-fold selectivity over other coagulation and fibrinolytic protease targets, comparing favorably with the best direct thrombin inhibitors known. EP217609 bound antithrombin with high affinity (KD = 30nM) and activated the serpin to rapidly (kass ∼ 106M−1s−1) and selectively (> 20-fold) inhibit factor Xa. The dual inhibitor moieties of EP217609 acted largely independently with only modest linkage effects of ligand occupancy of one inhibitor moiety on the potency of the other (∼ 5-fold). In contrast, avidin binding effectively neutralized the potency of both inhibitor moieties (20- to 100-fold). These findings demonstrate the superior anticoagulant efficacy and rapid avidin neutralizability of EP217609 compared with anticoagulants that target thrombin or factor Xa alone. PMID:22144183

  4. Factor Xa inhibitors versus vitamin K antagonists for preventing cerebral or systemic embolism in patients with atrial fibrillation.

    PubMed

    Bruins Slot, Karsten M H; Berge, Eivind

    2013-08-08

    Anticoagulant treatment with vitamin K antagonists (VKAs) is aimed at preventing thromboembolic complications and has been the therapy of choice for most people with non-valvular atrial fibrillation (AF) for many decades. A new class of anticoagulants, the factor Xa inhibitors, appear to have several pharmacological and practical advantages over VKAs. To assess the effectiveness and safety of treatment with factor Xa inhibitors versus VKAs for the prevention of cerebral or systemic embolic events in people with AF. We searched the trials registers of the Cochrane Stroke Group and the Cochrane Heart Group (June 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 10), MEDLINE (1950 to April 2013) and EMBASE (1980 to April 2013). In an effort to identify further published, unpublished and ongoing trials we searched trials registers and Google Scholar (July 2012). We also screened reference lists and contacted pharmaceutical companies, authors and sponsors of relevant published trials. Randomised controlled trials that directly compared the effects of long-term treatment (more than four weeks) with factor Xa inhibitors and VKAs for the prevention of cerebral and systemic embolism in patients with AF. We included patients with and without a previous stroke or TIA. The primary efficacy outcome was the composite endpoint of all strokes and other systemic embolic events. Two authors independently assessed trial quality and the risk of bias, and extracted data. We calculated a weighted estimate of the typical treatment effect across trials using the odds ratio (OR) with 95% confidence interval (CI) by means of a fixed-effect model. However, in the case of moderate or high heterogeneity of treatment effects, we used a random-effects model to compare the overall treatment effects and performed a pre-specified sensitivity analysis excluding any fully open-label studies. We included data from 42,084 participants randomised into

  5. Blood flow controls coagulation onset via the positive feedback of factor VII activation by factor Xa

    PubMed Central

    2010-01-01

    Background Blood coagulation is a complex network of biochemical reactions, which is peculiar in that it is time- and space-dependent, and has to function in the presence of rapid flow. Recent experimental reports suggest that flow plays a significant role in its regulation. The objective of this study was to use systems biology techniques to investigate this regulation and to identify mechanisms creating a flow-dependent switch in the coagulation onset. Results Using a detailed mechanism-driven model of tissue factor (TF)-initiated thrombus formation in a two-dimensional channel we demonstrate that blood flow can regulate clotting onset in the model in a threshold-like manner, in agreement with existing experimental evidence. Sensitivity analysis reveals that this is achieved due to a combination of the positive feedback of TF-bound factor VII activation by activated factor X (Xa) and effective removal of factor Xa by flow from the activating patch depriving the feedback of "ignition". The level of this trigger (i.e. coagulation sensitivity to flow) is controlled by the activity of tissue factor pathway inhibitor. Conclusions This mechanism explains the difference between red and white thrombi observed in vivo at different shear rates. It can be speculated that this is a special switch protecting vascular system from uncontrolled formation and spreading of active coagulation factors in vessels with rapidly flowing blood. PMID:20102623

  6. The relative molecular mass dependence of the anti-factor Xa properties of heparin.

    PubMed Central

    Ellis, V; Scully, M F; Kakkar, V V

    1986-01-01

    The effect of heparin fractions of various Mr, with high affinity for antithrombin III, on the kinetics of the reaction between factor Xa and antithrombin III have been studied using purified human proteins. Each of the heparin fractions, which varied between pentasaccharide and Mr 32,000, accelerated the inhibition of factor Xa although an increasing rate of inhibition was observed with increasing Mr. The chemically synthesized pentasaccharide preparation (Mr 1714) gave a maximum inhibition rate constant of 1.2 X 10(7) M-1 X min-1, compared with 6.3 X 10(4) M-1 X min-1 in the absence of heparin, and this rose progressively to 4.2 X 10(8) M-1 X min-1 with the two fractions of highest Mr (22,500 and 32,000). The 35-fold difference in inhibition rates observed with the high-affinity fractions was virtually abolished by the presence of 0.3 M-NaCl. The disparity in these rates of inhibition was shown to be due to a change in the Km for factor Xa when a two-substrate model of heparin catalysis was used. The Km for factor Xa rose from 28 nM for the fraction of Mr 32,000 to 770 nM for the pentasaccharide, whilst 0.3 M-NaCl also caused an increase in Km with the high-Mr fraction. These data suggest that the increased rates of inhibition observed with heparins of higher Mr may be due to an involvement of heparin binding to factor Xa as well as to antithrombin III. PMID:3800942

  7. Structure and property based design of factor Xa inhibitors: biaryl pyrrolidin-2-ones incorporating basic heterocyclic motifs.

    PubMed

    Young, Robert J; Borthwick, Alan D; Brown, David; Burns-Kurtis, Cynthia L; Campbell, Matthew; Chan, Chuen; Charbaut, Marie; Convery, Máire A; Diallo, Hawa; Hortense, Eric; Irving, Wendy R; Kelly, Henry A; King, N Paul; Kleanthous, Savvas; Mason, Andrew M; Pateman, Anthony J; Patikis, Angela N; Pinto, Ivan L; Pollard, Derek R; Senger, Stefan; Shah, Gita P; Toomey, John R; Watson, Nigel S; Weston, Helen E; Zhou, Ping

    2008-01-01

    Structure and property based drug design was exploited in the synthesis of sulfonamidopyrrolidin-2-one-based factor Xa (fXa) inhibitors, incorporating basic biaryl P4 groups, producing highly potent inhibitors with significant anticoagulant activities and encouraging oral pharmacokinetic profiles.

  8. Structure and property based design of factor Xa inhibitors: pyrrolidin-2-ones with biaryl P4 motifs.

    PubMed

    Young, Robert J; Borthwick, Alan D; Brown, David; Burns-Kurtis, Cynthia L; Campbell, Matthew; Chan, Chuen; Charbaut, Marie; Chung, Chun-wa; Convery, Máire A; Kelly, Henry A; Paul King, N; Kleanthous, Savvas; Mason, Andrew M; Pateman, Anthony J; Patikis, Angela N; Pinto, Ivan L; Pollard, Derek R; Senger, Stefan; Shah, Gita P; Toomey, John R; Watson, Nigel S; Weston, Helen E

    2008-01-01

    Structure and property based drug design was exploited in the synthesis of sulfonamidopyrrolidin-2-one-based factor Xa (fXa) inhibitors, incorporating biaryl P4 groups, producing highly potent inhibitors with encouraging oral pharmacokinetic profiles and significant but sub-optimal anticoagulant activities.

  9. [Anti-factor Xa activity of enoxaparin for thromboprophylaxis in nonsurgical patients is dependent on body mass].

    PubMed

    Jiménez, David; Díaz, Gema; Iglesias, Ana; César, Jesús; García-Avello, Angel; Martí, David; Escobar, Carlos; Vidal, Rafael; Sueiro, Antonio

    2008-12-01

    Thromboprophylaxis with a fixed dose of low-molecular-weight heparin is recommended for hospitalized acutely ill medical patients. The purpose of this study was to assess whether the anti-factor Xa (anti-Xa) activity of enoxaparin prescribed for venous thromboembolism prophylaxis depends on body mass index (BMI) in patients hospitalized for an acute respiratory disease. All patients admitted to the respiratory medicine department (January-December 2006) for an acute respiratory disease, and for whom pharmacologic thromboprophylaxis was indicated, were included in the study. Anti-Xa activity was measured 4 hours after administration of enoxaparin on the third day of hospitalization. The primary outcome was anti-Xa activity in relation to BMI. One hundred twelve patients were enrolled. Mean anti-Xa activity decreased with each BMI quartile (0.28, 0.23, 0.15, and 0.13 U/mL for quartiles 1, 2, 3, and 4, respectively). In the multivariate analysis, BMI was the only predictor of inadequate anti-Xa activity (odds ratio, 1.14; 95% confidence interval, 10.5-1.24; P< .002) after adjustment for age, sex, and serum creatinine levels. Two episodes of symptomatic proximal deep vein thrombosis were diagnosed in the month after hospitalization; both occurred in patients who had inadequate anti-Xa activity. Anti-Xa activity is dependent on BMI in hospitalized acute medical patients receiving enoxaparin for thromboprophylaxis.

  10. Stabilizing of a globular protein by a highly complex water network: a molecular dynamics simulation study on factor Xa.

    PubMed

    Wallnoefer, Hannes G; Handschuh, Sandra; Liedl, Klaus R; Fox, Thomas

    2010-06-03

    The role of water molecules is increasingly attracting attention in structural biology, and many studies have demonstrated their crucial contribution to the stability and function of proteins. Here, we present molecular dynamics studies on factor Xa (fXa) to investigate the effect of water molecules in this serine protease. fXa is a key enzyme in the blood coagulation cascade, and thus, an important target for antithrombotic drugs. A reasonable representation of the structure is crucial for an investigation at the molecular level and, thus, a prerequisite for structure-based drug design. Simulations of well-resolved fXa X-ray structures with different sets of water molecules show the importance of a well-determined water set for the simulation. We discuss implications of different water sets on the structure and dynamics of fXa.

  11. Pharmacophore identification, in silico screening, and virtual library design for inhibitors of the human factor Xa.

    PubMed

    Krovat, Eva M; Frühwirth, Karin H; Langer, Thierry

    2005-01-01

    Factor Xa inhibitors are innovative anticoagulant agents that provide a better safety/efficacy profile compared to other anticoagulative drugs. A chemical feature-based modeling approach was applied to identify crucial pharmacophore patterns from 3D crystal structures of inhibitors bound to human factor Xa (Pdb entries 1fjs, 1kns, 1eqz) using the software LIGANDSCOUT and CATALYST. The complex structures were selected regarding the criteria of high inhibitory potency (i.e. all ligands show K(i) values against factor Xa in the subnanomolar range) and good resolution (i.e. at least 2.2 A) in order to generate selective and high quality pharmacophore models. The resulting chemical-feature based hypotheses were used for virtual screening of commercial molecular databases such as the WDI database. Furthermore, a ligand-based molecular modeling approach was performed to obtain common-feature hypotheses that represent the relevant chemical interactions between 10 bioactive factor Xa inhibitors and the protein, respectively. In a next step a virtual combinatorial library was designed in order to generate new compounds with similar chemical and spatial properties as known inhibitors. The software tool ILIB DIVERSE was used for this procedure in order to provide new scaffolds of this group of anticoagulants. Finally we present the combination of these two techniques, hence virtual screening was performed with selective pharmacophore models in a focused virtual combinatorial database. De novo derived molecular scaffolds that were able to adequately satisfy the pharmacophore criteria are revealed and are promising templates for candidates for further development.

  12. A four component coupling strategy for the synthesis of D-phenylglycinamide-derived non-covalent factor Xa inhibitors.

    PubMed

    Sheehan, Scott M; Masters, John J; Wiley, Michael R; Young, Stephen C; Liebeschuetz, John W; Jones, Stuart D; Murray, Christopher W; Franciskovich, Jeffrey B; Engel, David B; Weber, Wayne W; Marimuthu, Jothirajah; Kyle, Jeffrey A; Smallwood, Jeffrey K; Farmen, Mark W; Smith, Gerald F

    2003-07-21

    A novel isonitrile derivative was synthesized and used in an Ugi four component coupling reaction to explore aryl group substitution effects on inhibition of the coagulation cascade serine protease factor Xa.

  13. Contemporary developments in the discovery of selective factor Xa inhibitors: A review.

    PubMed

    Patel, Nirav R; Patel, Dushyant V; Murumkar, Prashant R; Yadav, Mange Ram

    2016-10-04

    Thrombosis is a leading cause of death in cardiovascular diseases such as myocardial infarction (MI), unstable angina and acute coronary syndrome (ACS) in the industrialized world. Venous thromboembolism is observed in about 1 million people every year in United States causing significant morbidity and mortality. Conventional antithrombotic therapy has been reported to have several disadvantages and limitations like inconvenience in oral administration, bleeding risks (heparin analogs), narrow therapeutic window and undesirable interactions with food and drugs (vitamin K antagonist-warfarin). The unmet medical demand for orally active safe anticoagulants has generated widespread interest among the medicinal chemists engaged in this field. To modulate blood coagulation, various enzymes involved in the coagulation process have received great attention as potential targets by various research groups for the development of oral anticoagulants. Among these enzymes, factor Xa (FXa) has remained the centre of attention in the last decade. Intensive research efforts have been made by various research groups for the development of small, safe and orally bioavailable FXa inhibitors. This review is an attempt to compile the research work of various researchers in the direction of development of FXa inhibitors reported since 2010 onward.

  14. Coagulation-induced shedding of platelet glycoprotein VI mediated by factor Xa.

    PubMed

    Al-Tamimi, Mohammad; Grigoriadis, George; Tran, Huy; Paul, Eldho; Servadei, Patricia; Berndt, Michael C; Gardiner, Elizabeth E; Andrews, Robert K

    2011-04-07

    This study evaluated shedding of the platelet collagen receptor, glycoprotein VI (GPVI) in human plasma. Collagen or other ligands induce metalloproteinase-mediated GPVI ectodomain shedding, generating approximately 55-kDa soluble GPVI (sGPVI) and approximately 10-kDa platelet-associated fragments. In the absence of GPVI ligands, coagulation of platelet-rich plasma from healthy persons induced GPVI shedding, independent of added tissue factor, but inhibitable by metalloproteinase inhibitor, GM6001. Factor Xa (FXa) common to intrinsic and tissue factor-mediated coagulation pathways was critical for sGPVI release because (1) shedding was strongly blocked by the FXa-selective inhibitor rivaroxaban but not FIIa (thrombin) inhibitors dabigatran or hirudin; (2) Russell viper venom that directly activates FX generated sGPVI, with complete inhibition by enoxaparin (inhibits FXa and FIIa) but not hirudin; (3) impaired GPVI shedding during coagulation of washed platelets resuspended in FX-depleted plasma was restored by adding purified FX; and (4) purified FXa induced GM6001-inhibitable GPVI shedding from washed platelets. In 29 patients with disseminated intravascular coagulation, mean plasma sGPVI was 53.9 ng/mL (95% confidence interval, 39.9-72.8 ng/mL) compared with 12.5 ng/mL (95% confidence interval, 9.0-17.3 ng/mL) in thrombocytopenic controls (n = 36, P < .0001), and 14.6 ng/mL (95% confidence interval, 7.9-27.1 ng/mL) in healthy subjects (n = 25, P = .002). In conclusion, coagulation-induced GPVI shedding via FXa down-regulates GPVI under procoagulant conditions. FXa inhibitors have an unexpected role in preventing GPVI down-regulation.

  15. Functional assembly of intrinsic coagulation proteases on monocytes and platelets. Comparison between cofactor activities induced by thrombin and factor Xa

    PubMed Central

    1992-01-01

    Generation of coagulation factor Xa by the intrinsic pathway protease complex is essential for normal activation of the coagulation cascade in vivo. Monocytes and platelets provide membrane sites for assembly of components of this protease complex, factors IXa and VIII. Under biologically relevant conditions, expression of functional activity by this complex is associated with activation of factor VIII to VIIIa. In the present studies, autocatalytic regulatory pathways operating on monocyte and platelet membranes were investigated by comparing the cofactor function of thrombin-activated factor VIII to that of factor Xa-activated factor VIII. Reciprocal functional titrations with purified human factor VIII and factor IXa were performed at fixed concentrations of human monocytes, CaCl2, factor X, and either factor IXa or factor VIII. Factor VIII was preactivated with either thrombin or factor Xa, and reactions were initiated by addition of factor X. Rates of factor X activation were measured using chromogenic substrate specific for factor Xa. The K1/2 values, i.e., concentration of factor VIIIa at which rates were half maximal, were 0.96 nM with thrombin- activated factor VIII and 1.1 nM with factor Xa-activated factor VIII. These values are close to factor VIII concentration in plasma. The Vsat, i.e., rates at saturating concentrations of factor VIII, were 33.3 and 13.6 nM factor Xa/min, respectively. The K1/2 and Vsat values obtained in titrations with factor IXa were not significantly different from those obtained with factor VIII. In titrations with factor X, the values of Michaelis-Menten coefficients (Km) were 31.7 nM with thrombin- activated factor VIII, and 14.2 nM with factor Xa-activated factor VIII. Maximal rates were 23.4 and 4.9 nM factor Xa/min, respectively. The apparent catalytic efficiency was similar with either form of factor VIIIa. Kinetic profiles obtained with platelets as a source of membrane were comparable to those obtained with monocytes

  16. Structure-based drug design of pyrrolidine-1, 2-dicarboxamides as a novel series of orally bioavailable factor Xa inhibitors.

    PubMed

    Van Huis, Chad A; Bigge, Christopher F; Casimiro-Garcia, Agustin; Cody, Wayne L; Dudley, Danette A; Filipski, Kevin J; Heemstra, Ronald J; Kohrt, Jeffrey T; Narasimhan, Lakshmi S; Schaum, Robert P; Zhang, Erli; Bryant, John W; Haarer, Staci; Janiczek, Nancy; Leadley, Robert J; McClanahan, Thomas; Thomas Peterson, J; Welch, Kathleen M; Edmunds, Jeremy J

    2007-06-01

    A novel series of pyrrolidine-1,2-dicarboxamides was discovered as factor Xa inhibitors using structure-based drug design. This series consisted of a neutral 4-chlorophenylurea P1, a biphenylsulfonamide P4 and a D-proline scaffold (1, IC(50) = 18 nM). Optimization of the initial hit resulted in an orally bioavailable, subnanomolar inhibitor of factor Xa (13, IC(50) = 0.38 nM), which was shown to be efficacious in a canine electrolytic model of thrombosis with minimal bleeding.

  17. Structure- and property-based design of factor Xa inhibitors: pyrrolidin-2-ones with acyclic alanyl amides as P4 motifs.

    PubMed

    Young, Robert J; Campbell, Matthew; Borthwick, Alan D; Brown, David; Burns-Kurtis, Cynthia L; Chan, Chuen; Convery, Máire A; Crowe, Miriam C; Dayal, Satish; Diallo, Hawa; Kelly, Henry A; King, N Paul; Kleanthous, Savvas; Mason, Andrew M; Mordaunt, Jackie E; Patel, Champa; Pateman, Anthony J; Senger, Stefan; Shah, Gita P; Smith, Paul W; Watson, Nigel S; Weston, Helen E; Zhou, Ping

    2006-12-01

    Structure-based drug design was exploited in the synthesis of 3-(6-chloronaphth-2-ylsulfonyl)aminopyrrolidin-2-one-based factor Xa (fXa) inhibitors, incorporating an alanylamide P4 group with acyclic tertiary amide termini. Optimized hydrophobic contacts of one amide substituent in P4 were complemented by hydrophobicity-modulating features in the second, producing potent fXa inhibitors including examples with excellent anticoagulant properties.

  18. Efficacy and safety of rivaroxaban compared with warfarin among elderly patients with nonvalvular atrial fibrillation in the Rivaroxaban Once Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF).

    PubMed

    Halperin, Jonathan L; Hankey, Graeme J; Wojdyla, Daniel M; Piccini, Jonathan P; Lokhnygina, Yuliya; Patel, Manesh R; Breithardt, Günter; Singer, Daniel E; Becker, Richard C; Hacke, Werner; Paolini, John F; Nessel, Christopher C; Mahaffey, Kenneth W; Califf, Robert M; Fox, Keith A A

    2014-07-08

    Nonvalvular atrial fibrillation is common in elderly patients, who face an elevated risk of stroke but difficulty sustaining warfarin treatment. The oral factor Xa inhibitor rivaroxaban was noninferior to warfarin in the Rivaroxaban Once Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF). This prespecified secondary analysis compares outcomes in older and younger patients. There were 6229 patients (44%) aged ≥75 years with atrial fibrillation and ≥2 stroke risk factors randomized to warfarin (target international normalized ratio=2.0-3.0) or rivaroxaban (20 mg daily; 15 mg if creatinine clearance <50 mL/min), double blind. The primary end point was stroke and systemic embolism by intention to treat. Over 10 866 patient-years, older participants had more primary events (2.57% versus 2.05%/100 patient-years; P=0.0068) and major bleeding (4.63% versus 2.74%/100 patient-years; P<0.0001). Stroke/systemic embolism rates were consistent among older (2.29% rivaroxaban versus 2.85% warfarin per 100 patient-years; hazard ratio=0.80; 95% confidence interval, 0.63-1.02) and younger patients (2.00% versus 2.10%/100 patient-years; hazard ratio=0.95; 95% confidence interval, 0.76-1.19; interaction P=0.313), as were major bleeding rates (≥75 years: 4.86% rivaroxaban versus 4.40% warfarin per 100 patient-years; hazard ratio=1.11; 95% confidence interval, 0.92-1.34; <75 years: 2.69% versus 2.79%/100 patient-years; hazard ratio=0.96; 95% confidence interval, 0.78-1.19; interaction P=0.336). Hemorrhagic stroke rates were similar in both age groups; there was no interaction between age and rivaroxaban response. Elderly patients had higher stroke and major bleeding rates than younger patients, but the efficacy and safety of rivaroxaban relative to warfarin did not differ with age, supporting rivaroxaban as an alternative for the elderly. © 2014 American Heart Association, Inc.

  19. Acylcarnitines are anticoagulants that inhibit factor Xa and are reduced in venous thrombosis, based on metabolomics data

    PubMed Central

    Deguchi, Hiroshi; Banerjee, Yajnavalka; Trauger, Sunia; Siuzdak, Gary; Kalisiak, Ewa; Fernández, José A.; Hoang, Linh; Tran, Minerva; Yegneswaran, Subramanian; Elias, Darlene J.

    2015-01-01

    In many patients with deep vein thrombosis and pulmonary embolism (venous thromboembolism, VTE), biomarkers or genetic risk factors have not been identified. To discover novel plasma metabolites associated with VTE risk, we employed liquid chromatography-mass spectrometry-based untargeted metabolomics, which do not target any specific metabolites. Using the Scripps Venous Thrombosis Registry population for a case-control study, we discovered that 10:1 and 16:1 acylcarnitines were low in plasmas of the VTE patient group compared with matched controls, respectively. Data from targeted metabolomics studies showed that several long-chain acylcarnitines (10:1, 12:0, 12:2, 18:1, and 18:2) were lower in the VTE group. Clotting assays were used to evaluate a causal relationship for low acylcarnitines in patients with VTE. Various acylcarnitines inhibited factor Xa-initiated clotting. Inhibition of factor Xa by acylcarnitines was greater for longer acyl chains. Mechanistic studies showed that 16:0 acylcarnitine had anticoagulant activity in the absence of factor Va or phospholipids. Surface plasmon resonance investigations revealed that 16:0 acylcarnitine was bound to factor Xa and that binding did not require the γ-carboxy glutamic acid domain. In summary, our study identified low plasma levels of acylcarnitines in patients with VTE and showed that acylcarnitines have anticoagulant activity related to an ability to bind and inhibit factor Xa. PMID:26175037

  20. The discovery of potent and long-acting oral factor Xa inhibitors with tetrahydroisoquinoline and benzazepine P4 motifs.

    PubMed

    Watson, Nigel S; Adams, Carl; Belton, David; Brown, David; Burns-Kurtis, Cynthia L; Chaudry, Laiq; Chan, Chuen; Convery, Máire A; Davies, David E; Exall, Anne M; Harling, John D; Irvine, Stephanie; Irving, Wendy R; Kleanthous, Savvas; McLay, Iain M; Pateman, Anthony J; Patikis, Angela N; Roethke, Theresa J; Senger, Stefan; Stelman, Gary J; Toomey, John R; West, Robert I; Whittaker, Caroline; Zhou, Ping; Young, Robert J

    2011-03-15

    The discovery and evaluation of potent and long-acting oral sulfonamidopyrrolidin-2-one factor Xa inhibitors with tetrahydroisoquinoline and benzazepine P4 motifs are described. Unexpected selectivity issues versus tissue plasminogen activator in the former series were addressed in the later, delivering a robust candidate for progression towards clinical studies. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. A NMR and MD study of the active site of factor Xa by selective inhibitors

    NASA Astrophysics Data System (ADS)

    Doan, B. T.; Fraternali, F.; Do, Q. T.; Atkinson, R. A.; Palmas, P.; Sklenar, V.; Wildgoose, P.; Strop, P.; Saudek, V.

    1998-02-01

    The structure of two selective inhibitors obtained by the screening of a vast combinatorial library, Ac-Tyr-Ile-Arg-Ile-NH2 and Ac-(4-amino-Phe)-(Cyc.-Gly)-NH2, in the active site of the blood clotting enzyme factor Xa was determined using transferred NOE NMR and simulated annealing (SA) under NMR constraints. The refined structures of the inhibitors were docked in the active site and SA was performed inside the enzyme which has been kept as a rigid charged template. The final structures were optimised by molecular dynamics simulation of the complexes in water. The inhibitors assume a compact, very well defined conformation embedded in the binding site without blocking the catalysis. The model allows to explain the mode of action, affinity and specificity. L'étude structurale d'inhibiteurs du facteur Xa, une enzyme de coagulation, obtenus par chimie combinatoire : Ac-Tyr-Ile-Arg-Ile-NH2, Ac-(4-amino-Phe)-(Cyc.-Gly)-NH2, a été réalisée par RMN NOE de transfert et modélisation moléculaire. Les structures ont été calculées sous contraintes RMN : géométrie de distance, recuit simulé et minimisation, affinées par une recherche conformationnelle et recuit de l'inhibiteur placé dans le site actif et optimisées par simulation de dynamique moléculaire du complexe dans l'eau. L'inhibiteur présente une structure compacte positionnée dans le site d'interaction hors d'accès du site catalytique. Ce modèle permet d'expliquer le mode d'action, l'affinité et la spécificité des peptides.

  2. Laser-induced lanthanide luminescence as a probe of metal ion-binding sites of human Factor Xa.

    PubMed

    Rhee, M J; Horrocks, W D; Kosow, D P

    1984-06-25

    7F0 ---- 5D0 excitation spectroscopy of Eu(III) has shown that human Factor Xa has two high affinity lanthanide ion-binding sites. The deuterium isotope effect on the reciprocal lifetime (tau-1) of excited Eu(III) in human Factor Xa has indicated that 2 to 3 water molecules remain on Eu(III) after being complexed by Factor Xa, suggesting that 3-6 ligand atoms are provided by the protein, probably through two or three gamma-carboxyglutamic acids (GLA). F orster -type interlanthanide energy transfer has been utilized to measure the distance between the high affinity metal ion-binding sites of human Factor Xa using Tb(III) as an energy donor and Nd(III), Ho(III), or Er(III) as energy acceptors. Tau-1 values of Tb(III) in the presence of the acceptor ions Nd(III), Ho(III), and Er(III) were 1.90, 1.66, and 1.76 ms-1, respectively, which compared to 1.31 ms-1 in the presence of the nonacceptor ion Gd(III), yield energy transfer efficiencies of 0.29, 0.20, and 0.24, respectively. From these efficiencies and published critical distances (R0) ( Horrocks , W. DeW ., Jr., Rhee , M-J., Snyder, A. P., and Sudnick , D. R. (1980) J. Am. Chem. Soc. 102, 3650-3652), the distance between two high affinity sites is estimated to be 10.7 A. Based on these data, we propose that the two high affinity sites of human Factor Xa consist of two paired GLA residues; GLA-19, GLA-20 and GLA-25, GLA-26 together with one of the remaining single GLA residues for each site.

  3. Selective and dual action orally active inhibitors of thrombin and factor Xa.

    PubMed

    Young, Robert J; Brown, David; Burns-Kurtis, Cynthia L; Chan, Chuen; Convery, Máire A; Hubbard, Julia A; Kelly, Henry A; Pateman, Anthony J; Patikis, Angela; Senger, Stefan; Shah, Gita P; Toomey, John R; Watson, Nigel S; Zhou, Ping

    2007-05-15

    The synthetic entry to new classes of dual fXa/thrombin and selective thrombin inhibitors with significant oral bioavailability is described. This was achieved through minor modifications to the sulfonamide group in our potent and selective fXa inhibitor (E)-2-(5-chlorothien-2-yl)-N-{(3S)-1-[(1S)-1-methyl-2-(morpholin-4-yl)-2-oxoethyl]-2-oxopyrrolidin-3-yl}ethenesulfonamide and these observed activity changes have been rationalised using structural studies.

  4. A novel microfluidic anti-factor Xa assay device for monitoring anticoagulant therapy at the point-of-care

    NASA Astrophysics Data System (ADS)

    Harris, Leanne F.; Rainey, Paul; Castro-López, Vanessa; O'Donnell, James S.; Killard, Anthony J.

    2013-05-01

    Millions of patients worldwide are receiving anticoagulant therapy to treat hypercoagulable diseases. While standard testing is still performed in the central laboratory, point-of-care (POC) diagnostics are being developed due to the increasing number of patients requiring long-term anticoagulation and with a need for more personalized and targeted therapy. Many POC devices on the market focus on clot measurement, a technique which is limited in terms of variability, highlighting the need for more reliable assays of anticoagulant status. The anti-Xa assay, a factor specific optical assay, was developed to measure the extent to which exogenous factor Xa (FXa) is inhibited by heparinantithrombin complexes. We have developed a novel microfluidic device and assay for monitoring the effect of heparin anticoagulant therapy at the point-of-care. The assay which was also developed in our institute is based on the anti-Xa assay principle but uses fluorescence as the method of detection. Our device is a disposable laminate microfluidic strip, fabricated from the cyclic polyolefin (COP), Zeonor®, which is extremely suitable for application to fluorescent device platforms. We present data on the execution of the anti-Xa assay in this microfluidic format, demonstrating that the assay can be used to measure heparin in human plasma samples from 0 to 0.8 U/ml, with average assay reproducibility of 8% and a rapid result obtained within 60 seconds. Results indicate that with further development, the fluorogenic anti-Xa assay and device could become a successful method for monitoring anticoagulant therapy.

  5. Group D prothrombin activators from snake venom are structural homologues of mammalian blood coagulation factor Xa.

    PubMed Central

    Rao, Veena S; Joseph, Jeremiah S; Kini, R Manjunatha

    2003-01-01

    Procoagulant venoms of several Australian elapids contain proteinases that specifically activate prothrombin; among these, Group D activators are functionally similar to coagulation factor Xa (FXa). Structural information on this class of prothrombin activators will contribute significantly towards understanding the mechanism of FXa-mediated prothrombin activation. Here we present the purification of Group D prothrombin activators from three Australian snake venoms (Hoplocephalus stephensi, Notechis scutatus scutatus and Notechis ater niger) using a single-step method, and their N-terminal sequences. The N-terminal sequence of the heavy chain of hopsarin D (H. stephensi) revealed that a fully conserved Cys-7 was substituted with a Ser residue. We therefore determined the complete amino acid sequence of hopsarin D. Hopsarin D shows approximately 70% similarity with FXa and approximately 98% similarity with trocarin D, a Group D prothrombin activator from Tropidechis carinatus. It possesses the characteristic Gla domain, two epidermal growth factor-like domains and a serine proteinase domain. All residues important for catalysis are conserved, as are most regions involved in interactions with factor Va and prothrombin. However, there are some structural differences. Unlike FXa, hopsarin D is glycosylated in both its chains: in light-chain residue 52 and heavy-chain residue 45. The glycosylation on the heavy chain is a large carbohydrate moiety adjacent to the active-site pocket. Overall, hopsarin D is structurally and functionally similar to mammalian coagulation FXa. PMID:12403650

  6. Molecular recognition of avirulence protein (avrxa5) by eukaryotic transcription factor xa5 of rice (Oryza sativa L.): insights from molecular dynamics simulations.

    PubMed

    Dehury, Budheswar; Maharana, Jitendra; Sahoo, Bikash Ranjan; Sahu, Jagajjit; Sen, Priyabrata; Modi, Mahendra Kumar; Barooah, Madhumita

    2015-04-01

    The avirulence gene avrxa5 of bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo) recognized by the resistant rice lines having corresponding resistance (xa5) gene in a gene-for-gene manner. We used a combinatorial approach involving protein-protein docking, molecular dynamics (MD) simulations and binding free energy calculations to gain novel insights into the gene-for-gene mechanism that governs the direct interaction of R-Avr protein. From the best three binding poses predicted by molecular docking, MD simulations were performed to explore the dynamic binding mechanism of xa5 and avrxa5. Molecular Mechanics/Poisson Boltzmann Surface Area (MM/PBSA) techniques were employed to calculate the binding free energy and to uncover the thriving force behind the molecular recognition of avrxa5 by eukaryotic transcription factor xa5. Binding free energy analysis revealed van der Waals term as the most constructive component that favors the xa5 and avrxa5 interaction. In addition, hydrogen bonds (H-bonds) and essential electrostatic interactions analysis highlighted amino acid residues Lys54/Asp870, Lys56/Ala868, Lys56/Ala866, Lys56/Glu871, Ile59/His862, Gly61/Phe858, His62/Arg841, His62/Leu856, Ser101/Ala872 and Ser105/Asp870 plays pivotal role for the energetically stability of the R-Avr complex. Insights gained from the present study are expected to unveil the molecular mechanisms that define the transcriptional activator mediated transcriptome modification in host plants. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Hysteresis-like binding of coagulation factors X/Xa to procoagulant activated platelets and phospholipids results from multistep association and membrane-dependent multimerization.

    PubMed

    Podoplelova, Nadezhda A; Sveshnikova, Anastasia N; Kurasawa, James H; Sarafanov, Andrey G; Chambost, Herve; Vasil'ev, Sergey A; Demina, Irina A; Ataullakhanov, Fazly I; Alessi, Marie-Christine; Panteleev, Mikhail A

    2016-06-01

    Binding of coagulation factors X (fX) and Xa (fXa) to activated platelets is required for the formation of membrane-dependent enzymatic complexes of intrinsic tenase and prothrombinase. We carried out an in-depth characterization of fX/fXa binding to phospholipids and gel-filtered, thrombin-activated platelets. Flow cytometry, surface plasmon resonance, and computational modeling were used to investigate interactions of fX/fXa with the membranes. Confocal microscopy was employed to study fXa binding to platelet thrombi formed in flowing whole blood under arterial conditions. Binding of fX/fXa to either vesicles or procoagulant platelets did not follow a traditional one-step reversible binding model. Their dissociation was a two-step process resulting in a plateau that was up to 10-fold greater than the saturation value observed in the association experiments. Computational modeling and experimental evidence suggested that this was caused by a combination of two-step association (mainly for fX) and multimerization on the membrane (mainly for fXa). Importantly, fX formed multimers with fXa, thereby improving its retention. The same binding/dissociation hysteresis was observed for annexin V known to form trimers on the membranes. Experiments with platelets from gray syndrome patients showed that alpha-granular factor Va provided an additional high-affinity binding site for fXa that did not affect the hysteresis. Confocal microscopy observation of fXa binding to platelet thrombi in a flow chamber and its wash-out confirmed that this phenomenon persisted under physiologically relevant conditions. This suggests its possible role of "locking" coagulation factors on the membrane and preventing their inhibition in plasma and removal from thrombi by flow.

  8. The effect of Ca2+, phospholipid and factor V on the anti-(factor Xa) activity of heparin and its high-affinity oligosaccharides.

    PubMed Central

    Barrowcliffe, T W; Havercroft, S J; Kemball-Cook, G; Lindahl, U

    1987-01-01

    The influence of Ca2+, phospholipid and Factor V was determined on the rate of inactivation of Factor Xa by antithrombin III, in the absence and in the presence of unfractionated heparin and of three high-affinity heparin oligosaccharides in the Mr range 1500-6000. In the absence of heparin the addition of Ca2+, phospholipid and Factor V caused a 4-fold decrease in rate of inactivation of Factor Xa. As concentrations of unfractionated heparin were increased the protective effect of Ca2+/phospholipid/Factor V was gradually abolished, and at a concentration of 2.4 nM there were no differences in rates of neutralization of Factor Xa in the presence or absence of Ca2+, phospholipid and Factor V. In contrast, heparin decasaccharide (Mr 3000) and pentasaccharide (Mr 1500) fragments were unable to overcome the protective effect of Ca2+/phospholipid/Factor V; in the presence of these components their catalytic efficiencies were 16-fold and 40-fold less respectively than that of unfractionated heparin. A heparin 20-22-saccharide fragment (Mr approx. 6000) gave similar inactivation rates in the presence and in the absence of Ca2+/phospholipid/Factor V. Human and bovine Factor Xa gave similar results. These results indicate that in the presence of Ca2+/phospholipid/Factor V optimum inhibition of Factor Xa requires a saccharide sequence of heparin additional to that involved in binding to antithrombin III. The use of free enzyme for the assessment of anti-(Factor Xa) activity of low-Mr heparin fractions could give misleading results. PMID:3606581

  9. Parenteral administration of factor Xa/IIa inhibitors limits experimental aortic aneurysm and atherosclerosis.

    PubMed

    Moran, Corey S; Seto, Sai-Wang; Krishna, Smriti M; Sharma, Surabhi; Jose, Roby J; Biros, Erik; Wang, Yutang; Morton, Susan K; Golledge, Jonathan

    2017-02-21

    Intraluminal thrombus is a consistent feature of human abdominal aortic aneurysm (AAA). Coagulation factor Xa (FXa) catalyses FII to thrombin (FIIa). We examined the effect of FXa/FIIa inhibition on experimental aortic aneurysm in apolipoprotein E-deficient (ApoE(-/-)) mice infused with angiotensin II (AngII). The concentration of FXa within the supra-renal aorta (SRA) correlated positively with SRA diameter. Parenteral administration of enoxaparin (FXa/IIa inhibitor) and fondaparinux (FXa inhibitor) over 14 days reduced to severity of aortic aneurysm and atherosclerosis in AngII-infused ApoE(-/-) mice. Enteral administration of the FIIa inhibitor dabigatran had no significant effect. Aortic protease-activated receptor (PAR)-2 expression increased in response to AngII infusion. Fondaparinux reduced SRA levels of FXa, FIIa, PAR-2, matrix metalloproteinase (MMP)2, Smad2/3 phosphorylation, and MOMA-2 positive cells in the mouse model. FXa stimulated Smad2/3 phosphorylation and MMP2 expression in aortic vascular smooth muscle cells (VSMC) in vitro. Expression of MMP2 in FXa-stimulated VSMC was downregulated in the presence of a PAR-2 but not a PAR-1 inhibitor. These findings suggest that FXa/FIIa inhibition limits aortic aneurysm and atherosclerosis severity due to down-regulation of vascular PAR-2-mediated Smad2/3 signalling and MMP2 expression. Inhibition of FXa/FIIa may be a potential therapy for limiting aortic aneurysm.

  10. Engineering Factor Xa Inhibitor with Multiple Platelet-Binding Sites Facilitates its Platelet Targeting

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanjun; Li, Ruyi; Lin, Yuan; Shui, Mengyang; Liu, Xiaoyan; Chen, Huan; Wang, Yinye

    2016-07-01

    Targeted delivery of antithrombotic drugs centralizes the effects in the thrombosis site and reduces the hemorrhage side effects in uninjured vessels. We have recently reported that the platelet-targeting factor Xa (FXa) inhibitors, constructed by engineering one Arg-Gly-Asp (RGD) motif into Ancylostoma caninum anticoagulant peptide 5 (AcAP5), can reduce the risk of systemic bleeding than non-targeted AcAP5 in mouse arterial injury model. Increasing the number of platelet-binding sites of FXa inhibitors may facilitate their adhesion to activated platelets, and further lower the bleeding risks. For this purpose, we introduced three RGD motifs into AcAP5 to generate a variant NR4 containing three platelet-binding sites. NR4 reserved its inherent anti-FXa activity. Protein-protein docking showed that all three RGD motifs were capable of binding to platelet receptor αIIbβ3. Molecular dynamics simulation demonstrated that NR4 has more opportunities to interact with αIIbβ3 than single-RGD-containing NR3. Flow cytometry analysis and rat arterial thrombosis model further confirmed that NR4 possesses enhanced platelet targeting activity. Moreover, NR4-treated mice showed a trend toward less tail bleeding time than NR3-treated mice in carotid artery endothelium injury model. Therefore, our data suggest that engineering multiple binding sites in one recombinant protein is a useful tool to improve its platelet-targeting efficiency.

  11. Parenteral administration of factor Xa/IIa inhibitors limits experimental aortic aneurysm and atherosclerosis

    PubMed Central

    Moran, Corey S.; Seto, Sai-Wang; Krishna, Smriti M.; Sharma, Surabhi; Jose, Roby J.; Biros, Erik; Wang, Yutang; Morton, Susan K.; Golledge, Jonathan

    2017-01-01

    Intraluminal thrombus is a consistent feature of human abdominal aortic aneurysm (AAA). Coagulation factor Xa (FXa) catalyses FII to thrombin (FIIa). We examined the effect of FXa/FIIa inhibition on experimental aortic aneurysm in apolipoprotein E-deficient (ApoE−/−) mice infused with angiotensin II (AngII). The concentration of FXa within the supra-renal aorta (SRA) correlated positively with SRA diameter. Parenteral administration of enoxaparin (FXa/IIa inhibitor) and fondaparinux (FXa inhibitor) over 14 days reduced to severity of aortic aneurysm and atherosclerosis in AngII-infused ApoE−/− mice. Enteral administration of the FIIa inhibitor dabigatran had no significant effect. Aortic protease-activated receptor (PAR)-2 expression increased in response to AngII infusion. Fondaparinux reduced SRA levels of FXa, FIIa, PAR-2, matrix metalloproteinase (MMP)2, Smad2/3 phosphorylation, and MOMA-2 positive cells in the mouse model. FXa stimulated Smad2/3 phosphorylation and MMP2 expression in aortic vascular smooth muscle cells (VSMC) in vitro. Expression of MMP2 in FXa-stimulated VSMC was downregulated in the presence of a PAR-2 but not a PAR-1 inhibitor. These findings suggest that FXa/FIIa inhibition limits aortic aneurysm and atherosclerosis severity due to down-regulation of vascular PAR-2-mediated Smad2/3 signalling and MMP2 expression. Inhibition of FXa/FIIa may be a potential therapy for limiting aortic aneurysm. PMID:28220880

  12. Cleavage of spike protein of SARS coronavirus by protease factor Xa is associated with viral infectivity

    SciTech Connect

    Du, Lanying; Kao, Richard Y.; Zhou, Yusen; He, Yuxian; Zhao, Guangyu; Wong, Charlotte; Jiang, Shibo; Yuen, Kwok-Yung; Jin, Dong-Yan; Zheng, Bo-Jian . E-mail: bzheng@hkucc.hku.hk

    2007-07-20

    The spike (S) protein of SARS coronavirus (SARS-CoV) has been known to recognize and bind to host receptors, whose conformational changes then facilitate fusion between the viral envelope and host cell membrane, leading to viral entry into target cells. However, other functions of SARS-CoV S protein such as proteolytic cleavage and its implications to viral infection are incompletely understood. In this study, we demonstrated that the infection of SARS-CoV and a pseudovirus bearing the S protein of SARS-CoV was inhibited by a protease inhibitor Ben-HCl. Also, the protease Factor Xa, a target of Ben-HCl abundantly expressed in infected cells, was able to cleave the recombinant and pseudoviral S protein into S1 and S2 subunits, and the cleavage was inhibited by Ben-HCl. Furthermore, this cleavage correlated with the infectivity of the pseudovirus. Taken together, our study suggests a plausible mechanism by which SARS-CoV cleaves its S protein to facilitate viral infection.

  13. The Tick-Derived Anticoagulant Madanin Is Processed by Thrombin and Factor Xa

    PubMed Central

    Figueiredo, Ana C.; de Sanctis, Daniele; Pereira, Pedro José Barbosa

    2013-01-01

    The cysteine-less peptidic anticoagulants madanin-1 and madanin-2 from the bush tick Haemaphysalis longicornis are the founding members of the MEROPS inhibitor family I53. It has been previously suggested that madanins exert their functional activity by competing with physiological substrates for binding to the positively charged exosite I (fibrinogen-binding exosite) of α-thrombin. We hereby demonstrate that competitive inhibition of α-thrombin by madanin-1 or madanin-2 involves binding to the enzyme's active site. Moreover, the blood coagulation factors IIa and Xa are shown to hydrolyze both inhibitors at different, although partially overlapping cleavage sites. Finally, the three-dimensional structure of the complex formed between human α-thrombin and a proteolytic fragment of madanin-1, determined by X-ray crystallography, elucidates the molecular details of madanin-1 recognition and processing by the proteinase. Taken together, the current findings establish the mechanism of action of madanins, natural anticoagulants that behave as cleavable competitive inhibitors of thrombin. PMID:23951260

  14. Basis for the Specificity and Activation of the Serpin Protein Z-dependent Proteinase Inhibitor (ZPI) as an Inhibitor of Membrane-associated Factor Xa

    SciTech Connect

    Huang, Xin; Dementiev, Alexey; Olson, Steven T.; Gettins, Peter G.W.

    2012-12-13

    The serpin ZPI is a protein Z (PZ)-dependent specific inhibitor of membrane-associated factor Xa (fXa) despite having an unfavorable P1 Tyr. PZ accelerates the inhibition reaction {approx}2000-fold in the presence of phospholipid and Ca{sup 2+}. To elucidate the role of PZ, we determined the x-ray structure of Gla-domainless PZ (PZ{sub {Delta}GD}) complexed with protein Z-dependent proteinase inhibitor (ZPI). The PZ pseudocatalytic domain bound ZPI at a novel site through ionic and polar interactions. Mutation of four ZPI contact residues eliminated PZ binding and membrane-dependent PZ acceleration of fXa inhibition. Modeling of the ternary Michaelis complex implicated ZPI residues Glu-313 and Glu-383 in fXa binding. Mutagenesis established that only Glu-313 is important, contributing {approx}5-10-fold to rate acceleration of fXa and fXIa inhibition. Limited conformational change in ZPI resulted from PZ binding, which contributed only {approx}2-fold to rate enhancement. Instead, template bridging from membrane association, together with previously demonstrated interaction of the fXa and ZPI Gla domains, resulted in an additional {approx}1000-fold rate enhancement. To understand why ZPI has P1 tyrosine, we examined a P1 Arg variant. This reacted at a diffusion-limited rate with fXa, even without PZ, and predominantly as substrate, reflecting both rapid acylation and deacylation. P1 tyrosine thus ensures that reaction with fXa or most other arginine-specific proteinases is insignificant unless PZ binds and localizes ZPI and fXa on the membrane, where the combined effects of Gla-Gla interaction, template bridging, and interaction of fXa with Glu-313 overcome the unfavorability of P1 Tyr and ensure a high rate of reaction as an inhibitor.

  15. Basis for the specificity and activation of the serpin protein Z-dependent proteinase inhibitor (ZPI) as an inhibitor of membrane-associated factor Xa.

    PubMed

    Huang, Xin; Dementiev, Alexey; Olson, Steven T; Gettins, Peter G W

    2010-06-25

    The serpin ZPI is a protein Z (PZ)-dependent specific inhibitor of membrane-associated factor Xa (fXa) despite having an unfavorable P1 Tyr. PZ accelerates the inhibition reaction approximately 2000-fold in the presence of phospholipid and Ca(2+). To elucidate the role of PZ, we determined the x-ray structure of Gla-domainless PZ (PZ(DeltaGD)) complexed with protein Z-dependent proteinase inhibitor (ZPI). The PZ pseudocatalytic domain bound ZPI at a novel site through ionic and polar interactions. Mutation of four ZPI contact residues eliminated PZ binding and membrane-dependent PZ acceleration of fXa inhibition. Modeling of the ternary Michaelis complex implicated ZPI residues Glu-313 and Glu-383 in fXa binding. Mutagenesis established that only Glu-313 is important, contributing approximately 5-10-fold to rate acceleration of fXa and fXIa inhibition. Limited conformational change in ZPI resulted from PZ binding, which contributed only approximately 2-fold to rate enhancement. Instead, template bridging from membrane association, together with previously demonstrated interaction of the fXa and ZPI Gla domains, resulted in an additional approximately 1000-fold rate enhancement. To understand why ZPI has P1 tyrosine, we examined a P1 Arg variant. This reacted at a diffusion-limited rate with fXa, even without PZ, and predominantly as substrate, reflecting both rapid acylation and deacylation. P1 tyrosine thus ensures that reaction with fXa or most other arginine-specific proteinases is insignificant unless PZ binds and localizes ZPI and fXa on the membrane, where the combined effects of Gla-Gla interaction, template bridging, and interaction of fXa with Glu-313 overcome the unfavorability of P1 Tyr and ensure a high rate of reaction as an inhibitor.

  16. Structure and property based design of factor Xa inhibitors: pyrrolidin-2-ones with monoaryl P4 motifs.

    PubMed

    Kleanthous, Savvas; Borthwick, Alan D; Brown, David; Burns-Kurtis, Cynthia L; Campbell, Matthew; Chaudry, Laiq; Chan, Chuen; Clarte, Marie-Olive; Convery, Máire A; Harling, John D; Hortense, Eric; Irving, Wendy R; Irvine, Stephanie; Pateman, Anthony J; Patikis, Angela N; Pinto, Ivan L; Pollard, Derek R; Roethka, Theresa J; Senger, Stefan; Shah, Gita P; Stelman, Gary J; Toomey, John R; Watson, Nigel S; West, Robert I; Whittaker, Caroline; Zhou, Ping; Young, Robert J

    2010-01-15

    Structure and property based drug design was exploited in the synthesis of sulfonamidopyrrolidin-2-one-based factor Xa inhibitors, incorporating neutral and basic monoaryl P4 groups, ultimately producing potent inhibitors with effective levels of anticoagulant activity and extended oral pharmacokinetic profiles. However, time dependant inhibition of Cytochrome P450 3A4 was a particular issue with this series. Copyright 2009 Elsevier Ltd. All rights reserved.

  17. Structure and property based design of factor Xa inhibitors: pyrrolidin-2-ones with aminoindane and phenylpyrrolidine P4 motifs.

    PubMed

    Young, Robert J; Adams, Carl; Blows, Mike; Brown, David; Burns-Kurtis, Cynthia L; Chan, Chuen; Chaudry, Laiq; Convery, Máire A; Davies, David E; Exall, Anne M; Foster, Graham; Harling, John D; Hortense, Eric; Irvine, Stephanie; Irving, Wendy R; Jackson, Steve; Kleanthous, Savvas; Pateman, Anthony J; Patikis, Angela N; Roethka, Theresa J; Senger, Stefan; Stelman, Gary J; Toomey, John R; West, Robert I; Whittaker, Caroline; Zhou, Ping; Watson, Nigel S

    2011-03-15

    The rational design, syntheses and evaluation of potent sulfonamidopyrrolidin-2-one-based factor Xa inhibitors incorporating aminoindane and phenylpyrrolidine P4 motifs are described. These series delivered highly potent anticoagulant compounds with excellent oral pharmacokinetic profiles; however, significant time dependant P450 inhibition was an issue for the aminoindane series, but this was not observed with the phenylpyrrolidine motif, which produced candidate quality molecules with potential for once-daily oral dosing in humans. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Structure-based design of novel guanidine/benzamidine mimics: potent and orally bioavailable factor Xa inhibitors as novel anticoagulants.

    PubMed

    Lam, Patrick Y S; Clark, Charles G; Li, Renhua; Pinto, Donald J P; Orwat, Michael J; Galemmo, Robert A; Fevig, John M; Teleha, Christopher A; Alexander, Richard S; Smallwood, Angela M; Rossi, Karen A; Wright, Matthew R; Bai, Stephen A; He, Kan; Luettgen, Joseph M; Wong, Pancras C; Knabb, Robert M; Wexler, Ruth R

    2003-10-09

    As part of an ongoing effort to prepare orally active factor Xa inhibitors using structure-based drug design techniques and molecular recognition principles, a systematic study has been performed on the pharmacokinetic profile resulting from replacing the benzamidine in the P1 position with less basic benzamidine mimics or neutral residues. It is demonstrated that lowering the pK(a) of the P1 ligand resulted in compounds (3-benzylamine, 15a; 1-aminoisoquinoline, 24a; 3-aminobenzisoxazole, 23a; 3-phenylcarboxamide, 22b; and 4-methoxyphenyl, 22a) with improved pharmacokinetic features mainly as a result of decreased clearance, increased volume of distribution, and enhanced oral absorption. This work resulted in a series of potent and orally bioavailable factor Xa inhibitors that ultimately led to the discovery of SQ311, 24a. SQ311, which utilizes a 1-aminoisoquinoline as the P1 ligand, inhibits factor Xa with a K(i) of 0.33 nM and demonstrates both good in vivo antithrombotic efficacy and oral bioavailability.

  19. Annexin A2 contributes to lung injury and fibrosis by augmenting factor Xa fibrogenic activity.

    PubMed

    Schuliga, Michael; Jaffar, Jade; Berhan, Asres; Langenbach, Shenna; Harris, Trudi; Waters, David; Lee, Peter V S; Grainge, Christopher; Westall, Glen; Knight, Darryl; Stewart, Alastair G

    2017-05-01

    In lung injury and disease, including idiopathic pulmonary fibrosis (IPF), extravascular factor X is converted into factor Xa (FXa), a coagulant protease with fibrogenic actions. Extracellular annexin A2 binds to FXa, augmenting activation of the protease-activated receptor-1 (PAR-1). In this study, the contribution of annexin A2 in lung injury and fibrosis was investigated. Annexin A2 immunoreactivity was observed in regions of fibrosis, including those associated with fibroblasts in lung tissue of IPF patients. Furthermore, annexin A2 was detected in the conditioned media and an EGTA membrane wash of human lung fibroblast (LF) cultures. Incubation with human plasma (5% vol/vol) or purified FXa (15-50 nM) evoked fibrogenic responses in LF cultures, with FXa increasing interleukin-6 (IL-6) production and cell number by 270 and 46%, respectively (P < 0.05, n = 5-8). The fibrogenic actions of plasma or FXa were attenuated by the selective FXa inhibitor apixaban (10 μM, or antibodies raised against annexin A2 or PAR-1 (2 μg/ml). FXa-stimulated LFs from IPF patients (n = 6) produced twice as much IL-6 as controls (n = 10) (P < 0.05), corresponding with increased levels of extracellular annexin A2. Annexin A2 gene deletion in mice reduced bleomycin-induced increases in bronchoalveolar lavage fluid (BALF) IL-6 levels and cell number (*P < 0.05; n = 4-12). Lung fibrogenic gene expression and dry weight were reduced by annexin A2 gene deletion, but lung levels of collagen were not. Our data suggest that annexin A2 contributes to lung injury and fibrotic disease by mediating the fibrogenic actions of FXa. Extracellular annexin A2 is a potential target for the treatment of IPF. Copyright © 2017 the American Physiological Society.

  20. Digoxin use in patients with atrial fibrillation and adverse cardiovascular outcomes: a retrospective analysis of the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF).

    PubMed

    Washam, Jeffrey B; Stevens, Susanna R; Lokhnygina, Yuliya; Halperin, Jonathan L; Breithardt, Günter; Singer, Daniel E; Mahaffey, Kenneth W; Hankey, Graeme J; Berkowitz, Scott D; Nessel, Christopher C; Fox, Keith A A; Califf, Robert M; Piccini, Jonathan P; Patel, Manesh R

    2015-06-13

    Digoxin is a widely used drug for ventricular rate control in patients with atrial fibrillation (AF), despite a scarcity of randomised trial data. We studied the use and outcomes of digoxin in patients in the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF). For this retrospective analysis, we included and classified patients from ROCKET AF on the basis of digoxin use at baseline and during the study. Patients in ROCKET AF were recruited from 45 countries and had AF and risk factors putting them at moderate-to-high risk of stroke, with or without heart failure. We used Cox proportional hazards regression models adjusted for baseline characteristics and drugs to investigate the association of digoxin with all-cause mortality, vascular death, and sudden death. ROCKET AF was registered with ClinicalTrials.gov, number NCT00403767. In 14,171 randomly assigned patients, digoxin was used at baseline in 5239 (37%). Patients given digoxin were more likely to be female (42% vs 38%) and have a history of heart failure (73% vs 56%), diabetes (43% vs 38%), and persistent AF (88% vs 77%; p<0·0001 for each comparison). After adjustment, digoxin was associated with increased all-cause mortality (5·41 vs 4·30 events per 100 patients-years; hazard ratio 1·17; 95% CI 1·04-1·32; p=0·0093), vascular death (3·55 vs 2·69 per 100 patient-years; 1·19; 1·03-1·39, p=0·0201), and sudden death (1·68 vs 1·12 events per 100 patient-years; 1·36; 1·08-1·70, p=0·0076). Digoxin treatment was associated with a significant increase in all-cause mortality, vascular death, and sudden death in patients with AF. This association was independent of other measured prognostic factors, and although residual confounding could account for these results, these data show the possibility of digoxin having these effects. A randomised trial of digoxin in treatment of AF patients

  1. Structure-guided creation of AcAP5-derived and platelet targeted factor Xa inhibitors.

    PubMed

    Zhu, Yuanjun; Lin, Yuan; Liu, Aihua; Shui, Mengyang; Li, Ruyi; Liu, Xiaoyan; Hu, Wenhui; Wang, Yinye

    2015-06-15

    Anticoagulants and anti-platelet agents are simultaneously administrated in clinical practice (i.e. percutaneous coronary intervention), which cause significant risk of systemic bleeding. Targeted delivery of anticoagulants to the activated platelets at sites of vascular injuries may condense the site-specific anticoagulant effect and reduce the hemorrhage side effects in uninjured vessels. To this end, we prepared three ancylostoma caninum anticoagulant peptide 5 (AcAP5) variants NR1, NR2 and NR3 engineered with a platelet-binding Arg-Gly-Asp (RGD) motif and evaluated their anti-Factor Xa (FXa) and platelet-binding effects. These RGD-containing AcAP5 variants were capable of interacting with platelet receptor αIIbβ3 as shown in computational analysis. All variants, especially NR2 and NR3, retained entirely the anti-FXa function of parent AcAP5. Moreover, they prevented the formation of occlusive thrombi in rat carotid artery injury model, suggesting that they inhibit platelet aggregation in vivo. Further functional investigation of NR3 demonstrated that NR3 inhibited platelet aggregation in vitro and FXa activity in vivo, and prolonged the coagulation time, all in a dose-dependent manner. Through flow cytometry assay, we confirmed the binding of NR3 to αIIbβ3 receptor. In mouse model of carotid artery endothelium injury, NR3-treated mice showed less tail bleeding time than AcAP5-treated mice, and aspirin plus NR3 treatment exhibited moderate reduction of blood loss compared with aspirin plus AcAP5 treatment. These results indicate the feasibility to engineer a novel FXa inhibitor specifically targeting the activated platelets, which centralizes its anticoagulation efficacy in the injured vascular endothelium and reduces the risk of systemic bleeding. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Deuterium Solvent Isotope Effect and Proton Inventory Studies of Factor Xa-catalyzed Reactions†

    PubMed Central

    Zhang, Daoning; Kovach, Ildiko M.

    2008-01-01

    Kinetic solvent isotope effects (KSIE) for the Factor Xa (FXa)-catalyzed activation of prothrombin in the presence and absence of Factor Va (FVa) and 5.0 ×10−5 M phospholipid vesicles, are slightly inverse, 0.82−0.93, when substrate concentrations are at 0.2 Km. This is consistent with rate-determining association of the enzyme-prothrombin assembly, rather than rate-limiting chemical transformation. FVa is known to effect a major conformational change to expose the first scissile bond in prothrombin, which is the likely event triggering a major solvent rearrangement. At prothrombin concentrations >5 Km the KSIE is 1.6 ± 0.3, when FXa is in 1 : 1 ratio with FVa, but becomes increasingly inverse, 0.30 ± 0.05 and 0.19 ± 0.04, when FXa : FVa 1:4, with increasing FXa concentration and substrate concentration. The rate-determining step changes with the conditions, but the chemical step is not limiting under any circumstance. This corroborates the proposed predominance of the meizothrombin pathway when FXa is well saturated with the prothrombin complex. In contrast, the FXa-catalyzed hydrolysis of N-α-Z-D-Arg-Gly-Arg-pNA·2HCl (S-2765) and H-D-Ile-L-Pro-L-Arg-pNA.HCl (S-2288) is most consistent with two-proton bridges forming at the transition state between Ser195 OγH and His57 Nε2 and His57 Nδ1 and Asp102 COOβ- at the active site, with transition state fractionation factors of ϕ1 = ϕ2 = 0.57 ± 0.07 and ϕS = 0.78 ± 0.16 for solvent rearrangement for S-2765, and ϕ1 = ϕ2 = 0.674 ± 0.001 for S-2288 under enzyme saturation with substrate at pH 8.40 and 25.0 ± 0.1 °C. The rate-determining step(s) in these reactions is most likely the cleavage of the C-N bond and departure of the leaving group. PMID:17115712

  3. Outcomes of temporary interruption of rivaroxaban compared with warfarin in patients with nonvalvular atrial fibrillation: results from the rivaroxaban once daily, oral, direct factor Xa inhibition compared with vitamin K antagonism for prevention of stroke and embolism trial in atrial fibrillation (ROCKET AF).

    PubMed

    Sherwood, Matthew W; Douketis, James D; Patel, Manesh R; Piccini, Jonathan P; Hellkamp, Anne S; Lokhnygina, Yuliya; Spyropoulos, Alex C; Hankey, Graeme J; Singer, Daniel E; Nessel, Christopher C; Mahaffey, Kenneth W; Fox, Keith A A; Califf, Robert M; Becker, Richard C

    2014-05-06

    During long-term anticoagulation in atrial fibrillation, temporary interruptions (TIs) of therapy are common, but the relationship between patient outcomes and TIs has not been well studied. We sought to determine reasons for TI, the characteristics of patients undergoing TI, and the relationship between anticoagulant and outcomes among patients with TI. In the Rivaroxaban Once Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF), a randomized, double-blind, double-dummy study of rivaroxaban and warfarin in nonvalvular atrial fibrillation, baseline characteristics, management, and outcomes, including stroke, non-central nervous system systemic embolism, death, myocardial infarction, and bleeding, were reported in participants who experienced TI (3-30 days) for any reason. The at-risk period for outcomes associated with TI was from TI start to 30 days after resumption of study drug. In 14 236 participants who received at least 1 dose of study drug, 4692 (33%) experienced TI. Participants with TI were similar to the overall ROCKET AF population in regard to baseline clinical characteristics. Only 6% (n=483) of TI incidences involved bridging therapy. Stroke/systemic embolism rates during the at-risk period were similar in rivaroxaban-treated and warfarin-treated participants (0.30% versus 0.41% per 30 days; hazard ratio [confidence interval]=0.74 [0.36-1.50]; P=0.40). Risk of major bleeding during the at-risk period was also similar in rivaroxaban-treated and warfarin-treated participants (0.99% versus 0.79% per 30 days; hazard ratio [confidence interval]=1.26 [0.80-2.00]; P=0.32). TI of oral anticoagulation is common and is associated with substantial stroke risks and bleeding risks that were similar among patients treated with rivaroxaban or warfarin. Further investigation is needed to determine the optimal management strategy in patients with atrial fibrillation

  4. β-D-glucosyl conjugates of highly potent inhibitors of blood coagulation factor Xa bearing 2-chorothiophene as a P1 motif.

    PubMed

    Lopopolo, Gianfranco; de Candia, Modesto; Panza, Luigi; Romano, Maria Rosaria; Lograno, Marcello Diego; Campagna, Francesco; Altomare, Cosimo

    2012-09-01

    We synthesized a novel O-glucoside of the recently reported potent factor Xa (fXa) inhibitor 1, which bears a 5-chlorothien-2-yl moiety and 1-isopropylpiperidine as fragments that bind the S1 and S4 enzyme pockets, respectively. A β-D-glucosyl unit was conjugated through an ether-linked C3-alkyl spacer to the central phenyl ring of 1. The synthesized β-D-glucose-based compound 16 achieved picomolar inhibitory potency against human fXa (K(i)=60 pM) and high selectivity over thrombin and other serine proteases. In addition to the chlorothienyl S1 binder, a large gain in ΔG resulted from the addition of protonated 1-isopropylpiperidine (ΔΔG=29.7-30.5 kJ mol(-1)), which should bind to the aromatic S4 pocket through efficient cation-π and C-H···π interactions. Instead, the C3-alkyl-linked glucose fragment, which is likely directed toward the solvent outside the enzyme binding site, improves ΔG by an average of 2.9-3.8 kJ mol(-1) . Compound 16 showed sub-micromolar in vitro anticoagulant activity, as assessed by prothrombin time (PT) and activated thromboplastin time (aPTT) clotting assays in pooled human plasma (PT(2) and aPTT(2) equal to 0.135 and 0.389 μM, respectively). Although compound 16 was 1.4-fold less active than parent compound 1 in the ex vivo anticoagulant assay in mice, it showed a significant (1.6-fold) prolongation of PT relative to controls (P<0.05) 60 min after oral dosing (75 mg kg(-1)). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Association Between Enoxaparin Dosage Adjusted by Anti-Factor Xa Trough Level and Clinically Evident Venous Thromboembolism After Trauma.

    PubMed

    Ko, Ara; Harada, Megan Y; Barmparas, Galinos; Chung, Kevin; Mason, Russell; Yim, Dorothy A; Dhillon, Navpreet; Margulies, Daniel R; Gewertz, Bruce L; Ley, Eric J

    2016-11-01

    Trauma patients are at high risk for developing venous thromboembolism (VTE). The VTE rate when enoxaparin sodium is dosed by anti-factor Xa (anti-Xa) trough level is not well described. To determine whether targeting a prophylactic anti-Xa trough level by adjusting the enoxaparin dose would reduce the VTE rate in trauma patients. Single-institution, historic vs prospective cohort comparison study at an urban, academic, level I trauma center. The prospective cohort was enrolled from August 2014 to May 2015 and compared with a historic cohort admitted from August 2013 to May 2014. Trauma patients who received enoxaparin adjusted by anti-Xa trough level (adjustment group) were compared with those who received enoxaparin sodium at a dosage of 30 mg twice daily (control group). Patients were excluded if they were younger than 18 years, had a length of hospital stay less than 2 days, or had preexisting deep vein thrombosis. Patients were excluded from the adjustment group for changes in the choice of thromboprophylaxis (heparin, enoxaparin once-daily dosing, early ambulation), hospital discharge before initial trough levels could be drawn, or incorrect timing of trough levels. Anti-Xa trough levels were monitored in patients in the adjustment group receiving 3 or more consecutive doses of enoxaparin sodium, 30 mg twice daily. Patients with a trough level of 0.1 IU/mL or lower received enoxaparin sodium increased by 10-mg increments. After providing 3 adjusted doses of enoxaparin, the trough level was redrawn and the dosage was adjusted as necessary. Patients in the control group received enoxaparin sodium at a dosage of 30 mg twice daily without adjustments. Rates of symptomatic VTE (deep vein thrombosis and pulmonary embolism, confirmed by duplex ultrasonography and chest computed tomographic angiography, respectively) and bleeding risk. A total of 205 patients (mean [SD] age, 41.3 [18.2] years; 75.1% male) were studied, 87 in the adjustment group and 118 in the

  6. Differential Mitogenic Effects of Single Chain Hepatocyte Growth Factor (HGF)/Scatter Factor and HGF/NK1 following Cleavage by Factor Xa*

    PubMed Central

    Pediaditakis, Peter; Monga, Satdarshan P. S.; Mars, Wendy M.; Michalopoulos, George K.

    2007-01-01

    Hepatocyte growth factor/scatter factor (HGF/SF) is a multifunctional cytokine that is involved in many normal as well as pathological conditions. HGF/NK1, a splice variant of HGF/SF, has been reported to have either antagonistic or agonistic effects with regard to c-Met signaling depending on the cell type. In these experiments, we have determined that HGF/NK1 is a potent mitogen for rat hepatocytes in culture. Furthermore, we have found that coagulation factor Xa (fXa) is capable of cleaving HGF/NK1 and single chain HGF/SF (scHGF/SF). The products resulting from cleavage of HGF/NK1 or scHGF/SF by fXa appear as single bands under non-reducing conditions. The reaction products from the digestion of HGF/NK1 by fXa were separated under reducing conditions, and the cleavage site, as determined by N-terminal sequencing, was located C-terminal to arginine 134. Previous work established that the heparin-binding domain for HGF/SF is located in the N domain of HGF/SF. Additionally, the dimerization of the HGF/SF receptor (c-Met) by the ligand HGF/NK1 is facilitated by heparin and related sulfonated sugars on the cell surface, whereas heparin is not required for HGF/SF-mediated dimerization. Cleavage of single chain HGF/SF or HGF/NK1 by factor Xa does not alter the affinity of the respective molecules for heparin, but it did variably affect the associated mitogenic activity of these factors. The associated mitogenic activity of HGF/NK1 was reduced by more than 90%, whereas the mitogenic activity of scHGF/SF was unaffected. This suggests mandatory maintenance of a steric interaction of the N domain and the first kringle domain for HGF/NK1 to act as an agonist for rat hepatocyte growth but is not required by full-length HGF/SF. PMID:11832492

  7. Coagulation factor Xa drives tumor cells into apoptosis through BH3-only protein Bim up-regulation

    SciTech Connect

    Borensztajn, Keren S. . E-mail: K.S.Borensztajn@amc.uva.nl; Bijlsma, Maarten F.; Groot, Angelique P.; Brueggemann, Lois W.; Versteeg, Henri H.; Reitsma, Pieter H.; Peppelenbosch, Maikel P.; Spek, C. Arnold

    2007-07-15

    Coagulation Factor (F)Xa is a serine protease that plays a crucial role during blood coagulation by converting prothrombin into active thrombin. Recently, however, it emerged that besides this role in coagulation, FXa induces intracellular signaling leading to different cellular effects. Here, we show that coagulation factor (F)Xa drives tumor cells of epithelial origin, but not endothelial cells or monocytes, into apoptosis, whereas it even enhances fibroblast survival. FXa signals through the protease activated receptor (PAR)-1 to activate extracellular-signal regulated kinase (ERK) 1/2 and p38. This activation is associated with phosphorylation of the transcription factor CREB, and in tumor cells with up-regulation of the BH3-only pro-apoptotic protein Bim, leading to caspase-3 cleavage, the main hallmark of apoptosis. Transfection of tumor cells with dominant negative forms of CREB or siRNA for either PAR-1, Bim, ERK1 and/or p38 inhibited the pro-apoptotic effect of FXa. In fibroblasts, FXa-induced PAR-1 activation leads to down-regulation of Bim and pre-treatment with PAR-1 or Bim siRNA abolishes proliferation. We thus provide evidence that beyond its role in blood coagulation, FXa plays a key role in cellular processes in which Bim is the central player in determining cell survival.

  8. Staphylococcal superantigen-like protein 10 (SSL10) inhibits blood coagulation by binding to prothrombin and factor Xa via their γ-carboxyglutamic acid (Gla) domain.

    PubMed

    Itoh, Saotomo; Yokoyama, Ryosuke; Kamoshida, Go; Fujiwara, Toshinobu; Okada, Hiromi; Takii, Takemasa; Tsuji, Tsutomu; Fujii, Satoshi; Hashizume, Hideki; Onozaki, Kikuo

    2013-07-26

    The staphylococcal superantigen-like protein (SSL) family is composed of 14 exoproteins sharing structural similarity with superantigens but no superantigenic activity. Target proteins of four SSLs have been identified to be involved in host immune responses. However, the counterparts of other SSLs have been functionally uncharacterized. In this study, we have identified porcine plasma prothrombin as SSL10-binding protein by affinity purification using SSL10-conjugated Sepharose. The resin recovered the prodomain of prothrombin (fragment 1 + 2) as well as factor Xa in pull-down analysis. The equilibrium dissociation constant between SSL10 and prothrombin was 1.36 × 10(-7) M in surface plasmon resonance analysis. On the other hand, the resin failed to recover γ-carboxyglutamic acid (Gla) domain-less coagulation factors and prothrombin from warfarin-treated mice, suggesting that the Gla domain of the coagulation factors is essential for the interaction. SSL10 prolonged plasma clotting induced by the addition of Ca(2+) and factor Xa. SSL10 did not affect the protease activity of thrombin but inhibited the generation of thrombin activity in recalcified plasma. S. aureus produces coagulase that non-enzymatically activates prothrombin. SSL10 attenuated clotting induced by coagulase, but the inhibitory effect was weaker than that on physiological clotting, and SSL10 did not inhibit protease activity of staphylothrombin, the complex of prothrombin with coagulase. These results indicate that SSL10 inhibits blood coagulation by interfering with activation of coagulation cascade via binding to the Gla domain of coagulation factor but not by directly inhibiting thrombin activity. This is the first finding that the bacterial protein inhibits blood coagulation via targeting the Gla domain of coagulation factors.

  9. Renal dysfunction as a predictor of stroke and systemic embolism in patients with nonvalvular atrial fibrillation: validation of the R(2)CHADS(2) index in the ROCKET AF (Rivaroxaban Once-daily, oral, direct factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation) and ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation) study cohorts.

    PubMed

    Piccini, Jonathan P; Stevens, Susanna R; Chang, YuChiao; Singer, Daniel E; Lokhnygina, Yuliya; Go, Alan S; Patel, Manesh R; Mahaffey, Kenneth W; Halperin, Jonathan L; Breithardt, Günter; Hankey, Graeme J; Hacke, Werner; Becker, Richard C; Nessel, Christopher C; Fox, Keith A A; Califf, Robert M

    2013-01-15

    We sought to define the factors associated with the occurrence of stroke and systemic embolism in a large, international atrial fibrillation (AF) trial. In ROCKET AF (Rivaroxaban Once-daily, oral, direct factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation), 14 264 patients with nonvalvular AF and creatinine clearance ≥30 mL/min were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards modeling was used to identify factors at randomization independently associated with the occurrence of stroke or non-central nervous system embolism based on intention-to-treat analysis. A risk score was developed in ROCKET AF and validated in ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation), an independent AF patient cohort. Over a median follow-up of 1.94 years, 575 patients (4.0%) experienced primary end-point events. Reduced creatinine clearance was a strong, independent predictor of stroke and systemic embolism, second only to prior stroke or transient ischemic attack. Additional factors associated with stroke and systemic embolism included elevated diastolic blood pressure and heart rate, as well as vascular disease of the heart and limbs (C-index 0.635). A model that included creatinine clearance (R(2)CHADS(2)) improved net reclassification index by 6.2% compared with CHA(2)DS(2)VASc (C statistic=0.578) and by 8.2% compared with CHADS(2) (C statistic=0.575). The inclusion of creatinine clearance <60 mL/min and prior stroke or transient ischemic attack in a model with no other covariates led to a C statistic of 0.590.Validation of R(2)CHADS(2) in an external, separate population improved net reclassification index by 17.4% (95% confidence interval, 12.1%-22.5%) relative to CHADS(2). In patients with nonvalvular AF at moderate to high risk of stroke, impaired renal function is a potent predictor of stroke and systemic embolism. Stroke risk stratification in patients

  10. Daboxin P, a Major Phospholipase A2 Enzyme from the Indian Daboia russelii russelii Venom Targets Factor X and Factor Xa for Its Anticoagulant Activity

    PubMed Central

    Iyer, Janaki Krishnamurthy; Shih, Norrapat; Majumder, Munmi; Mattaparthi, Venkata Satish Kumar; Mukhopadhyay, Rupak; Doley, Robin

    2016-01-01

    In the present study a major protein has been purified from the venom of Indian Daboia russelii russelii using gel filtration, ion exchange and Rp-HPLC techniques. The purified protein, named daboxin P accounts for ~24% of the total protein of the crude venom and has a molecular mass of 13.597 kDa. It exhibits strong anticoagulant and phospholipase A2 activity but is devoid of any cytotoxic effect on the tested normal or cancerous cell lines. Its primary structure was deduced by N-terminal sequencing and chemical cleavage using Edman degradation and tandem mass spectrometry. It is composed of 121 amino acids with 14 cysteine residues and catalytically active His48 -Asp49 pair. The secondary structure of daboxin P constitutes 42.73% of α-helix and 12.36% of β-sheet. It is found to be stable at acidic (pH 3.0) and neutral pH (pH 7.0) and has a Tm value of 71.59 ± 0.46°C. Daboxin P exhibits anticoagulant effect under in-vitro and in-vivo conditions. It does not inhibit the catalytic activity of the serine proteases but inhibits the activation of factor X to factor Xa by the tenase complexes both in the presence and absence of phospholipids. It also inhibits the tenase complexes when active site residue (His48) was alkylated suggesting its non-enzymatic mode of anticoagulant activity. Moreover, it also inhibits prothrombinase complex when pre-incubated with factor Xa prior to factor Va addition. Fluorescence emission spectroscopy and affinity chromatography suggest the probable interaction of daboxin P with factor X and factor Xa. Molecular docking analysis reveals the interaction of the Ca+2 binding loop; helix C; anticoagulant region and C-terminal region of daboxin P with the heavy chain of factor Xa. This is the first report of a phospholipase A2 enzyme from Indian viper venom which targets both factor X and factor Xa for its anticoagulant activity. PMID:27089306

  11. Kinetics of the activation of human prothrombin by human coagulation factor Xa. Initial rate studies in the presence of Ca2+ and phospholipid.

    PubMed

    Kosow, D P; Orthner, C L

    1979-10-10

    Steady state kinetic studies have been performed to investigate the formation of thrombin from prothrombin by human coagulation Factor Xa in the presence of Ca2+ and phospholipid. The concentration of ligand which gives 50% of the maximum velocity (K0.5) is 2.3 mM for Ca2+, 7.4 microM for phospholipid, and 0.006 microM for prothrombin. Hill plots of the Ca2+ enhancement of the reaction give a Hill coefficient of 3.1, indicating positive cooperativity. The initial velocity patterns are consistent with an ordered addition of reactants with phospholipid as the second reactant to bind to the enzyme. Although our results do not differentiate between Ca2+ or the prothrombin substrate as the first reactant to bind to Factor Xa, it is established that Ca2+ can bind to Factor Xa in the absence of the other reactants. Thus, the most probable order of addition of reactants is Ca2+, phospholipid, and the prothrombin substrate. Plots of (v)-1 versus (prothrombin)-1 or (v)-1 versus [(Ca2+)3]-1 at several constant concentrations of phospholipid indicate that the major effect of phospholipid is to increase the turnover number of Factor Xa.

  12. Andexanet alfa: a recombinant mimetic of human factor Xa for the reversal of anticoagulant therapies.

    PubMed

    Escolar, G; Diaz-Ricart, M; Arellano-Rodrigo, E

    2017-05-01

    Activated coagulation factor X (FXa) is a common target for classic and newer anticoagulants. Parenteral anticoagulants with an indirect inhibitory action on FXa (low-molecular-weight heparins) have a well-established clinical efficacy in the prophylaxis and therapy of thromboembolic conditions. More recently developed direct oral anticoagulants (DOACs) have emerged as a new class of antithrombotic drugs. Rivaroxaban, apixaban and edoxaban are direct inhibitors of FXa approved for the management of venous thromboembolism and stroke prevention in atrial fibrillation. Although these DOACs are associated with fewer hemorrhagic side effects than classic vitamin K antagonists, bleeding is still a main complication. FXa antagonists had no specific agents that could reverse their antihemostatic effects. Andexanet alfa is a modified, recombinant human FXa molecule with an enhanced ability to bind to both direct and indirect FXa inhibitors, but unable to contribute to blood coagulation mechanisms. Andexanet alfa is designed to reverse the anticoagulant effects of FXa inhibitors. This review will address the preclinical pharmacology and the main aspects of the clinical development of andexanet alfa for the reversal of anticoagulant therapies with an inhibitory action on FXa. It will also summarize additional completed or ongoing studies on andexanet alfa available to the scientific community until present. Copyright 2017 Clarivate Analytics.

  13. Assessment of anti-factor Xa activity of heparin in binary parenteral nutrition admixtures for premature neonates.

    PubMed

    Foinard, A; Perez, M; Barthélémy, C; Lannoy, D; Flamein, F; Storme, L; Tournoys, A; Décaudin, B; Odou, P

    2015-07-01

    An in vitro study was carried out to determine the anti-Xa activity of heparin in binary parenteral nutrition (BPN) admixtures for premature neonates in our neonatal intensive care unit (NICU) after a 24-hour infusion, as well as to assess drug interaction with a 50% glucose solution. Two types of bags were prepared: (1) BPN admixtures (composition defined in the NICU) including sodium heparin at 77 UI/mL and (2) bags containing only G50% with sodium heparin at 193 UI/mL. The anti-Xa activity of heparin was measured in bags at T0, after the 24-hour infusion and in eluates at the outlet of the infusion line after 24hours, using a validated chromogenic anti-Xa method. Comparisons of the mean concentration observed with the theoretical value for anti-Xa activity were performed with the Student t-test. Mean values of anti-Xa activity do not differ significantly from the values expected for all conditions. We found a slight variation in anti-Xa activity when infused over 24hours for both types of bags, with and without in-line filtration, showing that heparin remains stable during this infusion period in both BPN admixtures and G50%.

  14. Reproducibility of the anti-Factor Xa and anti-Factor IIa assays applied to enoxaparin solution.

    PubMed

    Martinez, Céline; Savadogo, Adama; Agut, Christophe; Anger, Pascal

    2013-01-01

    Enoxaparin is a widely used subcutaneously administered antithrombotic agent comprising a complex mixture of glycosaminoglycan chains. Owing to this complexity, its antithrombotic potency cannot be defined by physicochemical methods and is therefore evaluated using an enzymatic assay of anti-Xa and anti-IIa activity. Maintaining consistent anti-Xa activity in the final medicinal product allows physicians to ensure administration of the appropriate dosage to their patients. Bioassays are usually complex and display poorer reproducibility than physicochemical tests such as HPLC assays. Here, we describe the implementation of a common robotic platform and standard release potency testing procedures for enoxaparin sodium injection (Lovenox, Sanofi, Paris, France) products at seven quality control sites within Sanofi. Qualification and analytical procedures, as well as data handling, were optimized and harmonized to improve assay reproducibility. An inter-laboratory study was performed in routine-release conditions. The coefficients of variation for repeatability and reproducibility in assessments of anti-Xa activity were 1.0% and 1.2%, respectively. The tolerance interval in reproducibility precision conditions, expressed as percentage potency, was 96.8-103.2% of the drug product target of 10,000 IU/ml, comparing favorably with the United States of America Pharmacopeia specification (90-110%). The maximum difference between assays in two different laboratories is expected to be 4.1%. The reproducibility characteristics of anti-IIa activity assessments were found to be similar. These results demonstrate the effectiveness of the standardization process established and allow for further improvements to quality control in Lovenox manufacture. This process guarantees closeness between actual and target potencies, as exemplified by the results of release assays obtained during a three-year period.

  15. Discovery of imidazo[1,5-c]imidazol-3-ones: weakly basic, orally active factor Xa inhibitors.

    PubMed

    Imaeda, Yasuhiro; Kuroita, Takanobu; Sakamoto, Hiroki; Kawamoto, Tetsuji; Tobisu, Mamoru; Konishi, Noriko; Hiroe, Katsuhiko; Kawamura, Masaki; Tanaka, Toshimasa; Kubo, Keiji

    2008-06-26

    The coagulation enzyme factor Xa (FXa) has been recognized as a promising target for the development of new antithrombotic agents. We previously found compound 1 to be an orally bioavailable FXa inhibitor in fasted monkeys; however, 1 showed poor bioavailability in rats and fed monkeys. To work out the pharmacokinetic problems, we focused our synthetic efforts on the chemical conversion of the 4-(imidazo[1,2- a]pyridin-5-yl)piperazine moiety of 1 to imidazolylpiperidine derivatives (fused and nonfused), which resulted in the discovery of the weakly basic imidazo[1,5- c]imidazol-3-one 3q as a potent and selective FXa inhibitor. Compound 3q showed favorable oral bioavailability in rats and monkeys under both fasted and fed conditions and antithrombotic efficacy in a rat model of venous thrombosis after oral administration, without a significant increase in bleeding time (unlike warfarin). On the basis of these promising properties, compound 3q was selected for further evaluation.

  16. Microfluidic Chip-Based Online Screening Coupled to Mass Spectrometry: Identification of Inhibitors of Thrombin and Factor Xa.

    PubMed

    Iyer, Janaki Krishnamoorthy; Otvos, Reka A; Kool, Jeroen; Kini, R Manjunatha

    2016-02-01

    Thrombin and factor Xa (FXa) are critical enzymes of the blood coagulation cascade and are excellent targets of anticoagulant agents. Natural sources present an array of anticoagulants that can be developed as antithrombotic drugs. High-resolution, online screening techniques have been developed for the identification of drug leads from complex mixtures. In this study, we have developed and optimized a microfluidic online screening technique coupled to nano-liquid chromatography (LC) and in parallel with a mass spectrometer for the identification of thrombin and FXa inhibitors in mixtures. Inhibitors eluting from the nano-LC were split postcolumn in a 1:1 ratio; half was fed into a mass spectrometer (where its mass is detected), and the other half was fed into a microfluidic chip (which acts as a microreactor for the online assays). With our platform, thrombin and FXa inhibitors were detected in the assay in parallel with their mass identification. These methods are suitable for the identification of inhibitors from sample amounts as low as sub-microliter volumes.

  17. CrataBL, a lectin and Factor Xa inhibitor, plays a role in blood coagulation and impairs thrombus formation.

    PubMed

    Salu, Bruno R; Ferreira, Rodrigo S; Brito, Marlon V; Ottaiano, Tatiana F; Cruz, José Walber M C; Silva, Mariana Cristina C; Correia, Maria Tereza S; Paiva, Patrícia M G; Maffei, Francisco Humberto A; Oliva, Maria Luiza Vilela

    2014-09-01

    Arterial thrombosis is an important complication of diabetes and cancer, being an important target for therapeutic intervention. Crataeva tapia bark lectin (CrataBL) has been previously shown to have hypoglycemiant effect and also to induce cancer cell apoptosis. It also showed inhibitory activity against Factor Xa (Kiapp=8.6 μm). In the present study, we evaluated the anti-thrombotic properties of CrataBL in arterial thrombosis model. CrataBL prolongs the activated partial thromboplastin time on human and mouse plasma, and it impairs the heparin-induced potentiation of antithrombin III and heparin-induced platelet activation in the presence of low-dose ADP. It is likely that the dense track of positive charge on CrataBL surface competes with the heparin ability to bind to antithrombin III and to stimulate platelets. In the photochemically induced thrombosis model in mice, in the groups treated with 1.25, 5.0, or 10 mg/kg CrataBL, prior to the thrombus induction, the time of total artery occlusion was prolonged by 33.38%, 65%, and 66.11%, respectively, relative to the time of the control group. In contrast to heparin, the bleeding time in CrataBL-treated mice was no longer than in the control. In conclusion, CrataBL was effective in blocking coagulation and arterial thrombus formation, without increasing bleeding time.

  18. Human plasma kallikrein and tissue kallikrein binding to a substrate based on the reactive site of a factor Xa inhibitor isolated from Bauhinia ungulata seeds.

    PubMed

    Oliva, M L; Andrade, S A; Batista, I F; Sampaio, M U; Juliano, M; Fritz, H; Auerswald, E A; Sampaio, C A

    1999-12-01

    Kunitz type Bauhinia ungulata factor Xa inhibitor (BuXI) was purified from B. ungulata seeds. BuXI inactivates factor Xa and human plasma kallikrein (HuPK) with Ki values of 18.4 and 6.9 nM, respectively. However, Bauhinia variegata trypsin inhibitor (BvTI) which is 70% homologous to BuXI does not inhibit factor Xa and is less efficient on HuPK (Ki = 80 nM). The comparison between BuXI and BvTI reactive site structure indicates differences at Met59, Thr66 and Met67 residues. The hydrolysis rate of quenched fluorescence peptide substrates based on BuXI reactive site sequence, Abz-VMIAALPRTMFIQ-EDDnp (leading peptide), by HuPK and porcine pancreatic kallikrein (PoPK) is low, but hydrolysis is enhanced with Abz-VMIAALPRTMQ-EDDnp, derived from the leading peptide shortened by removing the dipeptide Phe-Ileu from the C-terminal portion, for HuPK (Km = 0.68 microM, k(cat)/Km = 1.3 x 10(6) M(-1) s(-1)), and the shorter substrate Abz-LPRTMQ-EDDnp is better for PoPK (Km = 0.66 microM, k(cat)/Km = 2.2 x 10(3) M(-1) s(-1)). The contribution of substrate methionine residues to HuPK and PoPK hydrolysis differs from that observed with factor Xa. The determined Km and k(cat) values suggest that the substrates interact with kallikreins the same as an enzyme and inhibitor interacts to form complexes.

  19. Qualitative and quantitative pharmacophore-similarity assessment of anthranilamide-based factor Xa inhibitors: applications on similar molecules with identical biological endpoints.

    PubMed

    Kumar, Sivakumar Prasanth; Rawal, Rakesh M; Pandya, Himanshu A; Jasrai, Yogesh T

    2016-01-01

    It is a conventional practice to exclude molecules with identical biological endpoints to avoid bias in the resulting hypothesis model. Despite the diverse chemical functionalities, the receptor interactions of such molecules are often unexplored. The present study motivates the selection of these molecules diversified by single atom or functional group compared to internal molecules as external set and helps in the understanding of corresponding effects toward receptor interactions and biological endpoints. Applied on anthranilamide-series of factor Xa analogs, the inhibitory activities were correlated (r(2) = 0.99) and validated (q(2) = 0.68) with distance-based pharmacophore descriptors using support vector machine. The selected external set molecules exhibited better prediction accuracy by securing activities less than one residual threshold. The effect on inhibitory activity was assessed by the examination of pharmacophore-similarity and its interactions with key residues of Human factor Xa enzyme using molecular docking approach. Furthermore, qualitative pharmacophore models were developed on the subset of molecular dataset divided as most actives, moderately actives and least actives, to recognize crucial activity governing pharmacophore features. The outcome of this study will bring new insights about the requirements of pharmacophore features and prioritizes its selection in the design and optimization of potent Xa inhibitors.

  20. OC-03 - Modelisation of the procoagulant properties of cancer cells and their capacity to alter the antithrombotic efficiency of LMWHs and specific inhibitors of factor Xa.

    PubMed

    Gerotziafas, G T; Rousseau, A; van Dreden, P; Mbemba, E; Gkalea, V; Khaterchi, A; Larsen, A; Elalamy, I

    2016-04-01

    The risk of venous thromboembolism varies according to the histological type of cancer. The failure of antithrombotic treatment is more frequent in cancer patients as compared to non-cancer ones. We aimed to elucidate the mechanism of activation of blood coagulation induced by cancer, the impact of chemo-resistance phenotype on the capacity of cancer cells to trigger thrombin generation and the alterations of the efficiency of LMWHs and the specific inhibitors of factor Xa (fondaparinux and apixaban) in the presence of cancer cells. Thrombin generation of human plasma was assessed in the presence of various cancer cell lines. The model of cancer-induced hypercoagulability was coupled to the research for the expression of procoagulant molecules by cancer cells. The pancreatic adenocarcinoma cells BXPC3 and the breast adenocarcinoma cells MCF7 were initially tested. The BXPC3 cells induce significantly higher thrombin generation as compared to the MCF7 cells. In the same line Marchetti et al. showed that malignant hematologic cells (NB4, HEL, and K562) and H69 small cell lung cells express different procoagulant potential on triggering thrombin generation of human plasma. The comparison of the procoagulant activity has been extended to cancer cell lines from various cancers (i.e. colon, ovarian and prostatic cancer) as well as to different cell lines of the same type of cancer. The differences of the cancer cell lines to trigger thrombin generation are mainly due to the expression of TF. The acquisition of chemoresistant phenotype by cancer cells is correlated with increased TF expression and enhancement of theit procoagulant activity. The ability of cancer cells to activate FXII is an alternative pathway of significant importance for some cancer cell lines (i.e. MCF7). Clinically relevant concentrations of LMWH and specific direct and indirect inhibitors of FXa (apixaban and fondaparinux) inhibit thrombin generation induced by cancer cells. The synergy between the

  1. Effects of factor Xa on the expression of proteins in femoral arteries from type 2 diabetic patients.

    PubMed

    López-Farré, Antonio J; Rodriguez-Sierra, Pablo; Modrego, Javier; Segura, Antonio; Martín-Palacios, Naiara; Saiz, Ana M; Zamorano-León, José J; Duarte, Juan; Serrano, Javier; Moñux, Guillermo

    2014-12-01

    Further to its pivotal role in haemostasis, factor Xa (FXa) promotes effects on the vascular wall. The purpose of the study was to evaluate if FXa modifies the expression level of energy metabolism and oxidative stress-related proteins in femoral arteries obtained from type 2 diabetic patients with end-stage vasculopathy. Femoral arteries were obtained from 12 type 2 diabetic patients who underwent leg amputation. Segments from the femoral arteries were incubated in vitro alone and in the presence of 25 nmol l(-1) FXa and 25 nmol l(-1) FXa + 50 nmol l(-1) rivaroxaban. In the femoral arteries, FXa increased triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase isotype 1 expression but decreased pyruvate dehydrogenase expression. These facts were accompanied by an increased content of acetyl-CoA. Aconitase activity was reduced in FXa-incubated femoral arteries as compared with control. Moreover, FXa increased the protein expression level of oxidative stress-related proteins which was accompanied by an increased malonyldialdehyde arterial content. The FXa inhibitor, rivaroxaban, failed to prevent the reduced expression of pyruvate dehydrogenase induced by FXa but reduced acetyl-CoA content and reverted the decreased aconitase activity observed with FXa alone. Rivaroxaban + FXa but not FXa alone increased the expression level of carnitine palmitoyltransferase I and II, two mitochondrial long chain fatty acid transporters. Rivaroxaban also prevented the increased expression of oxidative stress-related proteins induced by FXa alone. In femoral isolated arteries from type 2 diabetic patients with end-stage vasculopathy, FXa promoted disruption of the aerobic mitochondrial metabolism. Rivaroxaban prevented such effects and even seemed to favour long chain fatty acid transport into mitochondria. © 2014 The British Pharmacological Society.

  2. Effects of factor Xa on the expression of proteins in femoral arteries from type 2 diabetic patients

    PubMed Central

    López-Farré, Antonio J; Rodriguez-Sierra, Pablo; Modrego, Javier; Segura, Antonio; Martín-Palacios, Naiara; Saiz, Ana M; Zamorano-León, José J; Duarte, Juan; Serrano, Javier; Moñux, Guillermo

    2014-01-01

    Aim Further to its pivotal role in haemostasis, factor Xa (FXa) promotes effects on the vascular wall. The purpose of the study was to evaluate if FXa modifies the expression level of energy metabolism and oxidative stress-related proteins in femoral arteries obtained from type 2 diabetic patients with end-stage vasculopathy. Methods Femoral arteries were obtained from 12 type 2 diabetic patients who underwent leg amputation. Segments from the femoral arteries were incubated in vitro alone and in the presence of 25 nmol l−1 FXa and 25 nmol l−1 FXa + 50 nmol l−1 rivaroxaban. Results In the femoral arteries, FXa increased triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase isotype 1 expression but decreased pyruvate dehydrogenase expression. These facts were accompanied by an increased content of acetyl-CoA. Aconitase activity was reduced in FXa-incubated femoral arteries as compared with control. Moreover, FXa increased the protein expression level of oxidative stress-related proteins which was accompanied by an increased malonyldialdehyde arterial content. The FXa inhibitor, rivaroxaban, failed to prevent the reduced expression of pyruvate dehydrogenase induced by FXa but reduced acetyl-CoA content and reverted the decreased aconitase activity observed with FXa alone. Rivaroxaban + FXa but not FXa alone increased the expression level of carnitine palmitoyltransferase I and II, two mitochondrial long chain fatty acid transporters. Rivaroxaban also prevented the increased expression of oxidative stress-related proteins induced by FXa alone. Conclusions In femoral isolated arteries from type 2 diabetic patients with end-stage vasculopathy, FXa promoted disruption of the aerobic mitochondrial metabolism. Rivaroxaban prevented such effects and even seemed to favour long chain fatty acid transport into mitochondria. PMID:25041869

  3. Characterization of a human coagulation factor Xa-binding site on Viperidae snake venom phospholipases A2 by affinity binding studies and molecular bioinformatics

    PubMed Central

    Faure, Grazyna; Gowda, Veerabasappa T; Maroun, Rachid C

    2007-01-01

    Background The snake venom group IIA secreted phospholipases A2 (SVPLA2), present in the Viperidae snake family exhibit a wide range of toxic and pharmacological effects. They exert their different functions by catalyzing the hydrolysis of phospholipids (PL) at the membrane/water interface and by highly specific direct binding to: (i) presynaptic membrane-bound or intracellular receptors; (ii) natural PLA2-inhibitors from snake serum; and (iii) coagulation factors present in human blood. Results Using surface plasmon resonance (SPR) protein-protein interaction measurements and an in vitro biological test of inhibition of prothrombinase activity, we identify a number of Viperidae venom SVPLA2s that inhibit blood coagulation through direct binding to human blood coagulation factor Xa (FXa) via a non-catalytic, PL-independent mechanism. We classify the SVPLA2s in four groups, depending on the strength of their binding. Molecular electrostatic potentials calculated at the surface of 3D homology-modeling models show a correlation with inhibition of prothrombinase activity. In addition, molecular docking simulations between SVPLA2 and FXa guided by the experimental data identify the potential FXa binding site on the SVPLA2s. This site is composed of the following regions: helices A and B, the Ca2+ loop, the helix C-β-wing loop, and the C-terminal fragment. Some of the SVPLA2 binding site residues belong also to the interfacial binding site (IBS). The interface in FXa involves both, the light and heavy chains. Conclusion We have experimentally identified several strong FXa-binding SVPLA2s that disrupt the function of the coagulation cascade by interacting with FXa by the non-catalytic PL-independent mechanism. By theoretical methods we mapped the interaction sites on both, the SVPLA2s and FXa. Our findings may lead to the design of novel, non-competitive FXa inhibitors. PMID:18062812

  4. At-line nanofractionation with parallel mass spectrometry and bioactivity assessment for the rapid screening of thrombin and factor Xa inhibitors in snake venoms.

    PubMed

    Mladic, Marija; Zietek, Barbara M; Iyer, Janaki Krishnamoorthy; Hermarij, Philip; Niessen, Wilfried M A; Somsen, Govert W; Kini, R Manjunatha; Kool, Jeroen

    2016-02-01

    Snake venoms comprise complex mixtures of peptides and proteins causing modulation of diverse physiological functions upon envenomation of the prey organism. The components of snake venoms are studied as research tools and as potential drug candidates. However, the bioactivity determination with subsequent identification and purification of the bioactive compounds is a demanding and often laborious effort involving different analytical and pharmacological techniques. This study describes the development and optimization of an integrated analytical approach for activity profiling and identification of venom constituents targeting the cardiovascular system, thrombin and factor Xa enzymes in particular. The approach developed encompasses reversed-phase liquid chromatography (RPLC) analysis of a crude snake venom with parallel mass spectrometry (MS) and bioactivity analysis. The analytical and pharmacological part in this approach are linked using at-line nanofractionation. This implies that the bioactivity is assessed after high-resolution nanofractionation (6 s/well) onto high-density 384-well microtiter plates and subsequent freeze drying of the plates. The nanofractionation and bioassay conditions were optimized for maintaining LC resolution and achieving good bioassay sensitivity. The developed integrated analytical approach was successfully applied for the fast screening of snake venoms for compounds affecting thrombin and factor Xa activity. Parallel accurate MS measurements provided correlation of observed bioactivity to peptide/protein masses. This resulted in identification of a few interesting peptides with activity towards the drug target factor Xa from a screening campaign involving venoms of 39 snake species. Besides this, many positive protease activity peaks were observed in most venoms analysed. These protease fingerprint chromatograms were found to be similar for evolutionary closely related species and as such might serve as generic snake protease

  5. D-phenylglycinol-derived non-covalent factor Xa inhibitors: effect of non-peptidic S4 linkage elements on affinity and anticoagulant activity.

    PubMed

    Klimkowski, Valentine J; Watson, Brian M; Wiley, Michael R; Liebeschuetz, John; Franciskovich, Jeffry B; Marimuthu, Jothirajah; Bastian, Jolie A; Sall, Daniel J; Smallwood, Jeffrey K; Chirgadze, Nikolay Y; Smith, Gerald F; Foster, Ronald S; Craft, Trelia; Sipes, Philip; Chastain, Marcia; Sheehan, Scott M

    2007-11-01

    Analogs to a series of D-phenylglycinamide-derived factor Xa inhibitors were discovered. It was found that the S4 amide linkage can be replaced with an ether linkage to reduce the peptide character of the molecules and that this substitution leads to an increase in binding affinity that is not predicted based on modeling. Inhibitors which incorporate ether, amino, or alkyl S4 linkage motifs exhibit similar levels of binding affinity and also demonstrate potent in vitro functional activity, however, binding affinity in this series is strongly dependent on the nature of the S1 binding element.

  6. Safety and efficacy of edoxaban, an oral factor Xa inhibitor, versus enoxaparin for thromboprophylaxis after total knee arthroplasty: the STARS E-3 trial.

    PubMed

    Fuji, Takeshi; Wang, Ching-Jen; Fujita, Satoru; Kawai, Yohko; Nakamura, Mashio; Kimura, Tetsuya; Ibusuki, Kei; Ushida, Hitoshi; Abe, Kenji; Tachibana, Shintaro

    2014-12-01

    This phase 3 trial compared the safety and efficacy of edoxaban, an oral direct factor Xa inhibitor, with enoxaparin sodium (enoxaparin) for thromboprophylaxis after total knee arthroplasty (TKA) in patients in Japan and Taiwan. In this randomized, double-blind, double-dummy study, patients received oral edoxaban 30 mg once daily beginning 6 to 24 hours postsurgery or enoxaparin 2000 IU (equivalent to 20 mg) subcutaneously twice daily beginning 24 to 36 hours postsurgery for 11 to 14 days. The primary efficacy endpoint was the composite of symptomatic pulmonary embolism and symptomatic and asymptomatic deep vein thrombosis. Safety endpoints included the incidence of major bleeding, clinically relevant non-major (CRNM) bleeding, major bleeding or CRNM bleeding, all bleeding events, adverse events, and adverse drug reactions. Of 716 patients enrolled, 360 and 356 were randomized to receive edoxaban or enoxaparin, respectively. The primary efficacy outcome occurred in 22/299 (7.4%) and 41/295 (13.9%) patients in the edoxaban and enoxaparin groups, respectively (relative risk reduction=46.8%), indicating non-inferiority (P <0.001) and superiority (P=0.010) of edoxaban versus enoxaparin. In the edoxaban and enoxaparin groups, major bleeding occurred in 4/354 (1.1%) versus 1/349 (0.3%) patients (P=0.373); major or CRNM bleeding occurred in 22/354 (6.2%) versus 13/349 (3.7%) patients (P=0.129), respectively. Edoxaban 30 mg once daily was more effective for thromboprophylaxis than subcutaneous enoxaparin 2000 IU twice daily following TKA and demonstrated a similar incidence of bleeding events. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. RoXaN, a Novel Cellular Protein Containing TPR, LD, and Zinc Finger Motifs, Forms a Ternary Complex with Eukaryotic Initiation Factor 4G and Rotavirus NSP3

    PubMed Central

    Vitour, Damien; Lindenbaum, Pierre; Vende, Patrice; Becker, Michelle M.; Poncet, Didier

    2004-01-01

    Rotavirus mRNAs are capped but not polyadenylated, and viral proteins are translated by the cellular translation machinery. This is accomplished through the action of the viral nonstructural protein NSP3, which specifically binds the 3′ consensus sequence of viral mRNAs and interacts with the eukaryotic translation initiation factor eIF4G I. To further our understanding of the role of NSP3 in rotavirus replication, we looked for other cellular proteins capable of interacting with this viral protein. Using the yeast two-hybrid assay, we identified a novel cellular protein-binding partner for rotavirus NSP3. This 110-kDa cellular protein, named RoXaN (rotavirus X protein associated with NSP3), contains a minimum of three regions predicted to be involved in protein-protein or nucleic acid-protein interactions. A tetratricopeptide repeat region, a protein-protein interaction domain most often found in multiprotein complexes, is present in the amino-terminal region. In the carboxy terminus, at least five zinc finger motifs are observed, further suggesting the capacity of RoXaN to bind other proteins or nucleic acids. Between these two regions exists a paxillin leucine-aspartate repeat (LD) motif which is involved in protein-protein interactions. RoXaN is capable of interacting with NSP3 in vivo and during rotavirus infection. Domains of interaction were mapped and correspond to the dimerization domain of NSP3 (amino acids 163 to 237) and the LD domain of RoXaN (amino acids 244 to 341). The interaction between NSP3 and RoXaN does not impair the interaction between NSP3 and eIF4G I, and a ternary complex made of NSP3, RoXaN, and eIF4G I can be detected in rotavirus-infected cells, implicating RoXaN in translation regulation. PMID:15047801

  8. Factor Xa inhibitors: S1 binding interactions of a series of N-{(3S)-1-[(1S)-1-methyl-2-morpholin-4-yl-2-oxoethyl]-2-oxopyrrolidin-3-yl}sulfonamides.

    PubMed

    Chan, Chuen; Borthwick, Alan D; Brown, David; Burns-Kurtis, Cynthia L; Campbell, Matthew; Chaudry, Laiq; Chung, Chun-wa; Convery, Máire A; Hamblin, J Nicole; Johnstone, Lisa; Kelly, Henry A; Kleanthous, Savvas; Patikis, Angela; Patel, Champa; Pateman, Anthony J; Senger, Stefan; Shah, Gita P; Toomey, John R; Watson, Nigel S; Weston, Helen E; Whitworth, Caroline; Young, Robert J; Zhou, Ping

    2007-04-05

    Factor Xa inhibitory activities for a series of N-{(3S)-1-[(1S)-1-methyl-2-morpholin-4-yl-2-oxoethyl]-2-oxopyrrolidin-3-yl}sulfonamides with different P1 groups are described. These data provide insight into binding interactions within the S1 primary specificity pocket; rationales are presented for the derived SAR on the basis of electronic interactions through crystal structures of fXa-ligand complexes and molecular modeling studies. A good correlation between in vitro anticoagulant activities with lipophilicity and the extent of human serum albumin binding is observed within this series of potent fXa inhibitors. Pharmacokinetic profiles in rat and dog, together with selectivity over other trypsin-like serine proteases, identified 1f as a candidate for further evaluation.

  9. Conserved Amblyomma americanum tick Serpin19, an inhibitor of blood clotting factors Xa and XIa, trypsin and plasmin, has anti-haemostatic functions.

    PubMed

    Kim, Tae Kwon; Tirloni, Lucas; Radulovic, Zeljko; Lewis, Lauren; Bakshi, Mariam; Hill, Creston; da Silva Vaz, Itabajara; Logullo, Carlos; Termignoni, Carlos; Mulenga, Albert

    2015-08-01

    Tick saliva serine protease inhibitors (serpins) facilitate tick blood meal feeding through inhibition of protease mediators of host defense pathways. We previously identified a highly conserved Amblyomma americanum serpin 19 that is characterised by its reactive center loop being 100% conserved in ixodid ticks. In this study, biochemical characterisation reveals that the ubiquitously transcribed A. americanum serpin 19 is an anti-coagulant protein, inhibiting the activity of five of the eight serine protease blood clotting factors. Pichia pastoris-expressed recombinant (r) A. americanum serpin 19 inhibits the enzyme activity of trypsin, plasmin and blood clotting factors (f) Xa and XIa, with stoichiometry of inhibition estimated at 5.1, 9.4, 23.8 and 28, respectively. Similar to typical inhibitory serpins, recombinant A. americanum serpin 19 forms irreversible complexes with trypsin, fXa and fXIa. At a higher molar excess of recombinant A. americanum serpin 19, fXIIa is inhibited by 82.5%, and thrombin (fIIa), fIXa, chymotrypsin and tryptase are inhibited moderately by 14-29%. In anti-hemostatic functional assays, recombinant A. americanum serpin 19 inhibits thrombin but not ADP and cathepsin G activated platelet aggregation, delays clotting in recalcification and thrombin time assays by up to 250s, and up to 40s in the activated partial thromboplastin time assay. Given A. americanum serpin 19 high cross-tick species conservation, and specific reactivity of recombinant A. americanum serpin 19 with antibodies to A. americanum tick saliva proteins, we conclude that recombinant A. americanum serpin 19 is a potential candidate for development of a universal tick vaccine.

  10. Thrombin generation induced by tissue factor plus ADP in human platelet rich plasma: A potential new measurement to assess the effect of the concomitant use of an oral factor Xa inhibitor edoxaban and P2Y12 receptor antagonists.

    PubMed

    Honda, Yuko; Morishima, Yoshiyuki

    2015-05-01

    Patients with atrial fibrillation undergoing percutaneous coronary intervention may require combination therapy with anticoagulants and antiplatelet agents. The objectives of this study were to establish an assay which can evaluate the effects of both anticoagulants and P2Y12 receptor antagonists and determine the effects of edoxaban, a direct factor Xa inhibitor, and P2Y12 receptor antagonists (clopidogrel and ticagrelor) alone and when combined. Human platelet-rich plasma (PRP) from healthy subjects was stimulated with adenosine diphosphate (ADP) plus tissue factor. Thrombin generation was measured by means of calibrated automated thrombography. Combination of 10μM ADP and low concentration (0.25 pM) tissue factor induced reproducible thrombin generation in human PRP. Edoxaban (40 and 80ng/mL), active metabolite of clopidogrel (AM-clopidogrel, 10 and 20μg/mL), and ticagrelor (3μg/mL) alone inhibited ADP plus tissue factor-induced thrombin generation. Edoxaban suppressed all 5 parameters (lag time, peak, time to peak, endogenous thrombin potential, and maximum rate), whereas AM-clopidogrel and ticagrelor inhibited 4 and 3 parameters, respectively. Concomitant treatment with edoxaban and AM-clopidogrel or ticagrelor produced an additive inhibition of thrombin generation compared to the single treatments. The thrombin generation assay induced by ADP plus tissue factor can detect the activities of both edoxaban and P2Y12 receptor antagonists. Combination of edoxaban and a P2Y12 receptor antagonist shows additive inhibition. These results suggest that ADP plus tissue factor-induced thrombin generation may be a useful measurement to assess the combination effects of anticoagulants and P2Y12 receptor antagonists in a single assay. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Efficacy and safety of rivaroxaban in patients with diabetes and nonvalvular atrial fibrillation: the Rivaroxaban Once-daily, Oral, Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF Trial).

    PubMed

    Bansilal, Sameer; Bloomgarden, Zachary; Halperin, Jonathan L; Hellkamp, Anne S; Lokhnygina, Yuliya; Patel, Manesh R; Becker, Richard C; Breithardt, Günter; Hacke, Werner; Hankey, Graeme J; Nessel, Christopher C; Singer, Daniel E; Berkowitz, Scott D; Piccini, Jonathan P; Mahaffey, Kenneth W; Fox, Keith A A

    2015-10-01

    The prevalence of both atrial fibrillation (AF) and diabetes mellitus (DM) are rising, and these conditions often occur together. Also, DM is an independent risk factor for stroke in patients with AF. We aimed to examine the safety and efficacy of rivaroxaban vs warfarin in patients with nonvalvular AF and DM in a prespecified secondary analysis of the ROCKET AF trial. We stratified the ROCKET AF population by DM status, assessed associations with risk of outcomes by DM status and randomized treatment using Cox proportional hazards models, and tested for interactions between randomized treatments. For efficacy, primary outcomes were stroke (ischemic or hemorrhagic) or non-central nervous system embolism. For safety, the primary outcome was major or nonmajor clinically relevant bleeding. The 5,695 patients with DM (40%) in ROCKET AF were younger, were more obese, and had more persistent AF, but fewer had previous stroke (the CHADS2 score includes DM and stroke). The relative efficacy of rivaroxaban and warfarin for prevention of stroke and systemic embolism was similar in patients with (1.74 vs 2.14/100 patient-years, hazard ratio [HR] 0.82) and without (2.12 vs 2.32/100 patient-years, HR 0.92) DM (interaction P = .53). The safety of rivaroxaban vs warfarin regarding major bleeding (HRs 1.00 and 1.12 for patients with and without DM, respectively; interaction P = .43), major or nonmajor clinically relevant bleeding (HRs 0.98 and 1.09; interaction P = .17), and intracerebral hemorrhage (HRs 0.62 and 0.72; interaction P = .67) was independent of DM status. Adjusted exploratory analyses suggested 1.3-, 1.5-, and 1.9-fold higher 2-year rates of stroke, vascular mortality, and myocardial infarction in DM patients. The relative efficacy and safety of rivaroxaban vs warfarin was similar in patients with and without DM, supporting use of rivaroxaban as an alternative to warfarin in diabetic patients with AF. Copyright © 2015 The Authors. Published by Elsevier Inc. All

  12. Factor Xa induces tissue factor expression in endothelial cells by P44/42 MAPK and NF-κB-dependent pathways

    PubMed Central

    Jiang, Rong; Wang, Ning-Ping; Tanaka, Kenichi A.; Levy, Jerrold H.; Guyton, Robert A.; Zhao, Zhi-Qing; Vinten-Johansen, Jakob

    2010-01-01

    Summary Background Tissue factor (TF) is an initiator of coagulation. The serine protease factor Xa (FXa) is the convergence point of the extrinsic and intrinsic components of the coagulation cascade. In addition to its hemostatic function, FXa elicits inflammatory responses in endothelial cells that may be important in surgical procedures in which inflammation is triggered. This study tested the hypothesis that FXa can upregulate TF on vascular endothelial cells by a MAPK- and NF-κB- dependent pathway. Methods and results Incubation of cultured human umbilical vein endothelial cells (HUVECs) with FXa increased TF protein expression and activity in a dose–dependent manner. Pre-incubation of HUVECs with the serine protease inhibitor antithrombin, which targets not only thrombin but also FXa and FIXa, inhibited FXa-induced TF expression, but the selective thrombin inhibitor hirudin did not inhibit FXa-induced TF expression, ruling out a thrombin-mediated pathway. After 10 min incubation with HUVECs, FXa rapidly induced P44/42 MAPK activation (immunoblotting of phosphorylated P44/42 MAPK) with a peak at 30 minutes. The MEK 1/2 inhibitor PD98059 partially reduced FXa-induced TF expression and activity (3.82±0.11 vs 6.54±0.08 fmol/min/cm2, P<0.05). NF-κB was activated by FXa, confirmed by cytoplasmic IkB α degradation and increased NF-κB P65 nuclear translocation. Interruption of the NF-κB pathway by the IkB α phosphorylation inhibitor Bay 11-7802 abrogated FXa-induced TF protein expression and activity (1.93± 0.02 vs 6.54±0.08 fmol/min/cm2, P<0.05). However, inhibition of PI3 kinase by LY 294002 did not attenuate FXa-induced TF protein expression and activity. Conclusions 1) FXa upregulates TF protein expression and activity in HUVECs 2) FXa-induced upregulation of TF is independent of the thrombin-PAR1 pathway, and 3) the MAPK and NF-kB pathways, but not PI3 kinase pathway, are involved in FXa-induced TF expression on human umbilical endothelial cells. FXa

  13. The discovery of (2R,4R)-N-(4-chlorophenyl)-N- (2-fluoro-4-(2-oxopyridin-1(2H)-yl)phenyl)-4-methoxypyrrolidine-1,2-dicarboxamide (PD 0348292), an orally efficacious factor Xa inhibitor.

    PubMed

    Kohrt, Jeffrey T; Bigge, Christopher F; Bryant, John W; Casimiro-Garcia, Agustin; Chi, Liguo; Cody, Wayne L; Dahring, Tawny; Dudley, Danette A; Filipski, Kevin J; Haarer, Staci; Heemstra, Ron; Janiczek, Nancy; Narasimhan, Lakshmi; McClanahan, Thomas; Peterson, J Thomas; Sahasrabudhe, Vaisheli; Schaum, Robert; Van Huis, Chad A; Welch, Kathleen M; Zhang, Erli; Leadley, Robert J; Edmunds, Jeremy J

    2007-08-01

    Herein, we report the discovery of novel, proline-based factor Xa inhibitors containing a neutral P1 chlorophenyl pharmacophore. Through the additional incorporation of 1-(4-amino-3-fluoro-phenyl)-1H-pyridin-2-one 22, as a P4 pharmacophore, we discovered compound 7 (PD 0348292). This compound is a selective, orally bioavailable, efficacious FXa inhibitor that is currently in phase II clinical trials for the treatment and prevention of thrombotic disorders.

  14. Synergistic effect of a factor Xa inhibitor, TAK-442, and antiplatelet agents on whole blood coagulation and arterial thrombosis in rats.

    PubMed

    Konishi, Noriko; Hiroe, Katsuhiko; Kawamura, Masaki

    2010-08-01

    Activated platelets facilitate blood coagulation by providing factor V and a procoagulant surface for prothrombinase. Here, we investigated the potential synergy of a potent factor Xa/prothrombinase inhibitor, TAK-442, plus aspirin or clopidogrel in preventing arterial thrombosis and whole blood coagulation. Thrombus formation was initiated by FeCl(3)-induced rat carotid injury. Bleeding time was evaluated with the rat tail transection model. Whole blood coagulation was assessed by thromboelastographic examination (TEG) for which blood obtained from control, aspirin-, or clopidogrel-treated rats was transferred to a TEG analyzer containing, collagen or adenosine diphosphate (ADP), and TAK-442 or vehicle. TAK-442 (3mg/kg, po), aspirin (100mg/kg, po) or clopidogrel (3mg/kg, po) alone had no significant effect on thrombus formation, whereas the combination of TAK-442 with aspirin and clopidogrel remarkably prolonged the time to thrombus formation without additional significant prolongation of bleeding time. TEG demonstrated that the onset of collagen-induced blood coagulation were slightly longer in aspirin-treated rats than control; however, when the blood from aspirin-treated rats was subsequently treated in vitro with 100 nM TAK-442, the onset of clotting was significantly prolonged. In contrast, only marginal prolongation was observed with TAK-442 treatment of blood from control animals. The onset time of ADP-induced blood coagulation was slightly longer in clopidogrel-treated rats compared with control, and it was further extended by TAK-442 treatment. These results demonstrate that blood coagulation can be markedly delayed by the addition of TAK-442 to antiplatelets treatment which could contribute to synergistic antithrombotic efficacy in these settings. (c) 2010 Elsevier Ltd. All rights reserved.

  15. Mutation of the rice XA21 predicted nuclear localization sequence does not affect resistance to Xanthomonas oryzae pv. oryzae

    DOE PAGES

    Wei, Tong; Chen, Tsung-Chi; Ho, Yuen Ting; ...

    2016-10-05

    Background: The rice receptor kinase XA21 confers robust resistance to the bacterial pathogenXanthomonas oryzae pv.oryzae(Xoo). We previously reported that XA21 is cleaved in transgenic plants overexpressing XA21 with a GFP tag (Ubi-XA21-GFP) and that the released C-terminal domain is localized to the nucleus. XA21 carries a predicted nuclear localization sequence (NLS) that directs the C-terminal domain to the nucleus in transient assays, whereas alanine substitutions in the NLS disrupt the nuclear localization. Methods: To determine if the predicted NLS is required for XA21-mediated immunityin planta, we generated transgenic plants overexpressing an XA21 variant carrying the NLS with the same alaninemore » substitutions (Ubi-XA21nls-GFP). Results: Ubi- XA21nls-GFP plants displayed slightly longer lesion lengths, higherXoo bacterial populations after inoculation and lower levels of reactive oxygen species production compared with the Ubi- XA21-GFP control plants. However, the Ubi- XA21nls-GFP plants express lower levels of protein than that observed inUbi- XA21-GFP. Discussion: These results demonstrate that the predicted NLS is not required for XA21-mediated immunity.« less

  16. Factor Xa releases matrix metalloproteinase-2 (MMP-2) from human vascular smooth muscle cells and stimulates the conversion of pro-MMP-2 to MMP-2: role of MMP-2 in factor Xa-induced DNA synthesis and matrix invasion.

    PubMed

    Rauch, Bernhard H; Bretschneider, Ellen; Braun, Marina; Schrör, Karsten

    2002-05-31

    Pro-matrix metalloproteinase-2 (pro-MMP-2) is expressed in vascular smooth muscle cells (SMCs). We report that activated coagulation factor X (FXa) induces the release of MMP-2 (65 kDa) from human SMCs. In addition, FXa cleaves pro-MMP-2 (72 kDa) into MMP-2. Pro-MMP-2 and MMP-2 were determined by gelatin zymography. MMP-2 was generated in conditioned medium containing pro-MMP-2 in a concentration-dependent fashion by FXa (3 to 100 nmol/L). FX at concentrations up to 300 nmol/L was ineffective. The conversion of pro-MMP-2 to MMP-2 was inhibited by a selective FXa inhibitor (DX-9065a) at 3 to 10 micromol/L. There was a concentration-dependent induction of an intermediate MMP-2 form (68 kDa) in lysates of FXa-treated cells. This indicates that cellular mechanisms are involved in FXa-induced conversion of pro-MMP-2. As a possible biological consequence of MMP-2 activation by FXa, DNA synthesis and matrix invasion of SMCs were determined. Both were stimulated by FXa and inhibited by the selective FXa inhibitor DX-9065a and the MMP inhibitor GM 6001 but not by hirudin or aprotinin. It is concluded that stimulation of SMCs by FXa increases the levels of MMP-2 in the extracellular space and that two different mechanisms are involved: release of active MMP-2 and cleavage of secreted pro-MMP-2. Both might contribute to the mitogenic potency of FXa and FXa-stimulated matrix invasion of SMCs.

  17. A computational modeling and molecular dynamics study of the Michaelis complex of human protein Z-dependent protease inhibitor (ZPI) and factor Xa (FXa)

    PubMed Central

    Chandrasekaran, Vasudevan; Lee, Chang Jun; Lin, Ping; Duke, Robert E.

    2009-01-01

    Protein Z-dependent protease inhibitor (ZPI) and antithrombin III (AT3) are members of the serpin superfamily of protease inhibitors that inhibit factor Xa (FXa) and other proteases in the coagulation pathway. While experimental structural information is available for the interaction of AT3 with FXa, at present there is no structural data regarding the interaction of ZPI with FXa, and the precise role of this interaction in the blood coagulation pathway is poorly understood. In an effort to gain a structural understanding of this system, we have built a solvent equilibrated three-dimensional structural model of the Michaelis complex of human ZPI/FXa using homology modeling, protein–protein docking and molecular dynamics simulation methods. Preliminary analysis of interactions at the complex interface from our simulations suggests that the interactions of the reactive center loop (RCL) and the exosite surface of ZPI with FXa are similar to those observed from X-ray crystal structure-based simulations of AT3/FXa. However, detailed comparison of our modeled structure of ZPI/FXa with that of AT3/FXa points to differences in interaction specificity at the reactive center and in the stability of the inhibitory complex, due to the presence of a tyrosine residue at the P1 position in ZPI, instead of the P1 arginine residue in AT3. The modeled structure also shows specific structural differences between AT3 and ZPI in the heparin-binding and flexible N-terminal tail regions. Our structural model of ZPI/FXa is also compatible with available experimental information regarding the importance for the inhibitory action of certain basic residues in FXa. PMID:19172319

  18. The antithrombotic activity of EP224283, a neutralizable dual factor Xa inhibitor/glycoprotein IIbIIIa antagonist, exceeds that of the coadministered parent compounds.

    PubMed

    Hechler, Béatrice; Freund, Monique; Alame, Ghina; Leguay, Cécile; Gaertner, Sébastien; Cazenave, Jean-Pierre; Petitou, Maurice; Gachet, Christian

    2011-08-01

    EP224283 combines in a single molecule idraparinux and tirofiban, which allows obtaining a predictable and sustained antiplatelet effect through the transfer of the pharmacokinetics properties of idraparinux to the anti-αIIbβ3 antagonist. The activity can be instantaneously neutralized by injection of avidin, a specific antidote. We have tested the effects of this new profile anticoagulant in various thrombosis models. The antithrombotic effect of EP224283 was compared with those of the parent compounds used alone or in association at doses achieving low to moderate inhibition of platelet aggregation ex vivo. In a model of systemic thromboembolism independent of thrombin generation, tirofiban and EP224283 had similar effects at equimolar doses. On the other hand, EP224283 was more potent than tirofiban or idraparinux under thrombin-dependent conditions. In a ferric chloride-induced thrombosis model, EP224283 was more potent than either parent compound or their combination. Similar results were obtained after atherosclerotic plaque rupture in ApoE(-/-) mice. Thus, the dual action of EP224283 exceeds that of the parent compounds used in combination. A possible explanation is that EP224283 could concentrate antithrombin inside the thrombus by binding to αIIbβ3 through the tirofiban moiety, as shown by immunolabeling of the occluded vessel. No prolongation of the bleeding time was observed at doses achieving strong antithrombotic effects, suggesting that low to moderate αIIbβ3 inhibition combined with factor Xa inhibition minimizes the bleeding risk. The favorable antithrombotic profile of EP224283 together with its possible neutralization by avidin makes it an interesting drug candidate for the treatment and prevention of acute ischemic events.

  19. Home treatment of patients with low-risk pulmonary embolism with the oral factor Xa inhibitor rivaroxaban. Rationale and design of the HoT-PE Trial.

    PubMed

    Barco, Stefano; Lankeit, Mareike; Binder, Harald; Schellong, Sebastian; Christ, Michael; Beyer-Westendorf, Jan; Duerschmied, Daniel; Bauersachs, Rupert; Empen, Klaus; Held, Matthias; Schwaiblmair, Martin; Fonseca, Cândida; Jiménez, David; Becattini, Cecilia; Quitzau, Kurt; Konstantinides, Stavros

    2016-07-04

    Pulmonary embolism (PE) is a potentially life-threatening acute cardiovascular syndrome. However, more than 95 % of patients are haemodynamically stable at presentation, and among them are patients at truly low risk who may qualify for immediate or early discharge. The Home Treatment of Pulmonary Embolism (HoT-PE) study is a prospective international multicentre single-arm phase 4 management (cohort) trial aiming to determine whether home treatment of acute low-risk PE with the oral factor Xa inhibitor rivaroxaban is feasible, effective, and safe. Patients with confirmed PE, who have no right ventricular dysfunction or free floating thrombi in the right atrium or ventricle, are eligible if they meet none of the exclusion criteria indicating haemodynamic instability, serious comorbidity or any condition mandating hospitalisation, or a familial/social environment unable to support home treatment. The first dose of rivaroxaban is given in hospital, and patients are discharged within 48 hours of presentation. Rivaroxaban is taken for at least three months. The primary outcome is symptomatic recurrent venous thromboembolism or PE-related death within three months of enrolment. Secondary outcomes include quality of life and patient satisfaction, and health care resource utilisation compared to existing data on standard-duration hospital treatment. HoT-PE is planned to analyse 1,050 enrolled patients, providing 80 % power to reject the null hypothesis that the recurrence rate of venous thromboembolism is >3 % with α≤0.05. If the hypothesis of HoT-PE is confirmed, early discharge and out-of-hospital treatment may become an attractive, potentially cost-saving option for a significant proportion of patients with acute PE.

  20. Lufaxin, a Novel Factor Xa Inhibitor from the Salivary Gland of the sand fly Lutzomyia longipalpis, Blocks PAR2 Activation and Inhibits Inflammation and Thrombosis in Vivo

    PubMed Central

    Collin, Nicolas; Assumpção, Teresa C. F.; Mizurini, Daniella M.; Gilmore, Dana; Dutra-Oliveira, Angélica; Kotsyfakis, Michalis; Sá-Nunes, Anderson; Teixeira, Clarissa; Ribeiro, José M. C.; Monteiro, Robson Q.; Valenzuela, Jesus G.; Francischetti, Ivo M. B.

    2012-01-01

    Objective Blood-sucking arthropods salivary glands (SGs) contain a remarkable diversity of antihemostatics. The aim of this study was to identify the unique salivary anticoagulant of the sand fly Lutzomyia longipalpis, which remained elusive for decades. Methods and Results Several L. longipalpis salivary proteins were expressed in HEK293 cells and screened for inhibition of blood coagulation. A novel 32.4-kDa molecule, named Lufaxin, was identified as a slow, tight, non-competitive, and reversible inhibitor of Factor Xa (FXa). Notably, Lufaxin primary sequence does not share similarity to any physiological or salivary inhibitors of coagulation reported to date. Lufaxin is specific for FXa and does not interact with FX, DEGR- FXa, or 15 other enzymes. In addition, Lufaxin blocks prothrombinase and increases both PT and aPTT. Surface plasmon resonance experiments revealed that FXa binds Lufaxin with a KD ~3 nM, and isothermal titration calorimetry determined a stoichiometry of 1:1. Lufaxin also prevents PAR2 activation by FXa in the MDA-MB-231 cell line and abrogates edema formation triggered by injection of FXa in the paw of mice. Moreover, Lufaxin prevents FeCl3-induced carotid artery thrombus formation and prolongs aPTT ex vivo, implying that it works as an anticoagulant in vivo. Finally, SG of sandflies was found to inhibit FXa and to interact with the enzyme. Conclusion Lufaxin belongs to a novel family of slow-tight FXa inhibitors, which display antithrombotic and antiinflamatory activities. It is a useful tool to understand FXa structural features and its role in pro-hemostatic and pro-inflammatory events. PMID:22796577

  1. Discovery of 1-[3-(aminomethyl)phenyl]-N-3-fluoro-2'-(methylsulfonyl)-[1,1'-biphenyl]-4-yl]-3-(trifluoromethyl)-1H-pyrazole-5-carboxamide (DPC423), a highly potent, selective, and orally bioavailable inhibitor of blood coagulation factor Xa.

    PubMed

    Pinto, D J; Orwat, M J; Wang, S; Fevig, J M; Quan, M L; Amparo, E; Cacciola, J; Rossi, K A; Alexander, R S; Smallwood, A M; Luettgen, J M; Liang, L; Aungst, B J; Wright, M R; Knabb, R M; Wong, P C; Wexler, R R; Lam, P Y

    2001-02-15

    Factor Xa (fXa) plays a critical role in the coagulation cascade, serving as the point of convergence of the intrinsic and extrinsic pathways. Together with nonenzymatic cofactor Va and Ca2+ on the phospholipid surface of platelets or endothelial cells, factor Xa forms the prothrombinase complex, which is responsible for the proteolysis of prothrombin to catalytically active thrombin. Thrombin, in turn, catalyzes the cleavage of fibrinogen to fibrin, thus initiating a process that ultimately leads to clot formation. Recently, we reported on a series of isoxazoline and isoxazole monobasic noncovalent inhibitors of factor Xa which show good potency in animal models of thrombosis. In this paper, we wish to report on the optimization of the heterocyclic core, which ultimately led to the discovery of a novel pyrazole SN429 (2b; fXa K(i) = 13 pM). We also report on our efforts to improve the oral bioavailability and pharmacokinetic profile of this series while maintaining subnanomolar potency and in vitro selectivity. This was achieved by replacing the highly basic benzamidine P1 with a less basic benzylamine moiety. Further optimization of the pyrazole core substitution and the biphenyl P4 culminated in the discovery of DPC423 (17h), a highly potent, selective, and orally active factor Xa inhibitor which was chosen for clinical development.

  2. Monitoring Low Molecular Weight Heparins at Therapeutic Levels: Dose-Responses of, and Correlations and Differences between aPTT, Anti-Factor Xa and Thrombin Generation Assays

    PubMed Central

    Thomas, Owain; Lybeck, Emanuel; Strandberg, Karin; Tynngård, Nahreen; Schött, Ulf

    2015-01-01

    Background Low molecular weight heparins (LMWH’s) are used to prevent and treat thrombosis. Tests for monitoring LMWH’s include anti-factor Xa (anti-FXa), activated partial thromboplastin time (aPTT) and thrombin generation. Anti-FXa is the current gold standard despite LMWH’s varying affinities for FXa and thrombin. Aim To examine the effects of two different LMWH’s on the results of 4 different aPTT-tests, anti-FXa activity and thrombin generation and to assess the tests’ concordance. Method Enoxaparin and tinzaparin were added ex-vivo in concentrations of 0.0, 0.5, 1.0 and 1.5 anti-FXa international units (IU)/mL, to blood from 10 volunteers. aPTT was measured using two whole blood methods (Free oscillation rheometry (FOR) and Hemochron Jr (HCJ)) and an optical plasma method using two different reagents (ActinFSL and PTT-Automat). Anti-FXa activity was quantified using a chromogenic assay. Thrombin generation (Endogenous Thrombin Potential, ETP) was measured on a Ceveron Alpha instrument using the TGA RB and more tissue-factor rich TGA RC reagents. Results Methods’ mean aPTT at 1.0 IU/mL LMWH varied between 54s (SD 11) and 69s (SD 14) for enoxaparin and between 101s (SD 21) and 140s (SD 28) for tinzaparin. ActinFSL gave significantly shorter aPTT results. aPTT and anti-FXa generally correlated well. ETP as measured with the TGA RC reagent but not the TGA RB reagent showed an inverse exponential relationship to the concentration of LMWH. The HCJ-aPTT results had the weakest correlation to anti-FXa and thrombin generation (Rs0.62–0.87), whereas the other aPTT methods had similar correlation coefficients (Rs0.80–0.92). Conclusions aPTT displays a linear dose-respone to LMWH. There is variation between aPTT assays. Tinzaparin increases aPTT and decreases thrombin generation more than enoxaparin at any given level of anti-FXa activity, casting doubt on anti-FXa’s present gold standard status. Thrombin generation with tissue factor-rich activator is

  3. RUBY-1: a randomized, double-blind, placebo-controlled trial of the safety and tolerability of the novel oral factor Xa inhibitor darexaban (YM150) following acute coronary syndrome.

    PubMed

    Steg, Ph Gabriel; Mehta, Shamir R; Jukema, J Wouter; Lip, Gregory Y H; Gibson, C Michael; Kovar, Frantisek; Kala, Petr; Garcia-Hernandez, Alberto; Renfurm, Ronny W; Granger, Christopher B

    2011-10-01

    To establish the safety, tolerability and most promising regimen of darexaban (YM150), a novel, oral, direct factor Xa inhibitor, for prevention of ischaemic events in acute coronary syndrome (ACS). In a 26-week, multi-centre, double-blind, randomized, parallel-group study, 1279 patients with recent high-risk non-ST-segment or ST-segment elevation ACS received one of six darexaban regimens: 5 mg b.i.d., 10 mg o.d., 15 mg b.i.d., 30 mg o.d., 30 mg b.i.d., or 60 mg o.d. or placebo, on top of dual antiplatelet treatment. Primary outcome was incidence of major or clinically relevant non-major bleeding events. The main efficacy outcome was a composite of death, stroke, myocardial infarction, systemic thromboembolism, and severe recurrent ischaemia. Bleeding rates were numerically higher in all darexaban arms vs. placebo (pooled HR: 2.275; 95% CI: 1.13-4.60, P = 0.022). Using placebo as reference (bleeding rate 3.1%), there was a dose-response relationship (P = 0.009) for increased bleeding with increasing darexaban dose (6.2, 6.5, and 9.3% for 10, 30, and 60 mg daily, respectively), which was statistically significant for 30 mg b.i.d. (P = 0.002). There was no decrease (indeed a numerical increase in the 30 and 60 mg dose arms) in efficacy event rates with darexaban, but the study was underpowered for efficacy. Darexaban showed good tolerability without signs of liver toxicity. Darexaban when added to dual antiplatelet therapy after ACS produces an expected dose-related two- to four-fold increase in bleeding, with no other safety concerns but no signal of efficacy. Establishing the potential of low-dose darexaban in preventing major cardiac events after ACS requires a large phase III trial. ClinicalTrials.gov Identifier: NCT00994292.

  4. Factor Xa activation of factor V is of paramount importance in initiating the coagulation system: lessons from a tick salivary protein.

    PubMed

    Schuijt, Tim J; Bakhtiari, Kamran; Daffre, Sirlei; Deponte, Kathleen; Wielders, Simone J H; Marquart, J Arnoud; Hovius, Joppe W; van der Poll, Tom; Fikrig, Erol; Bunce, Matthew W; Camire, Rodney M; Nicolaes, Gerry A F; Meijers, Joost C M; van 't Veer, Cornelis

    2013-07-16

    Generation of active procoagulant cofactor factor Va (FVa) and its subsequent association with the enzyme activated factor X (FXa) to form the prothrombinase complex is a pivotal initial event in blood coagulation and has been the subject of investigative effort, speculation, and controversy. The current paradigm assumes that FV activation is initiated by limited proteolysis by traces of (meizo) thrombin. Recombinant tick salivary protein TIX-5 was produced and anticoagulant properties were studied with the use of plasma, whole blood, and purified systems. Here, we report that TIX-5 specifically inhibits FXa-mediated FV activation involving the B domain of FV and show that FXa activation of FV is pivotal for plasma and blood clotting. Accordingly, tick feeding is impaired on TIX-5 immune rabbits, displaying the in vivo importance of TIX-5. Our data elucidate a unique molecular mechanism by which ticks inhibit the host's coagulation system. From our data, we propose a revised blood coagulation scheme in which direct FXa-mediated FV activation occurs in the initiation phase during which thrombin-mediated FV activation is restrained by fibrinogen and inhibitors.

  5. Mutation of the rice XA21 predicted nuclear localization sequence does not affect resistance to Xanthomonas oryzae pv. oryzae

    SciTech Connect

    Wei, Tong; Chen, Tsung-Chi; Ho, Yuen Ting; Ronald, Pamela C.

    2016-10-05

    Background: The rice receptor kinase XA21 confers robust resistance to the bacterial pathogenXanthomonas oryzae pv.oryzae(Xoo). We previously reported that XA21 is cleaved in transgenic plants overexpressing XA21 with a GFP tag (Ubi-XA21-GFP) and that the released C-terminal domain is localized to the nucleus. XA21 carries a predicted nuclear localization sequence (NLS) that directs the C-terminal domain to the nucleus in transient assays, whereas alanine substitutions in the NLS disrupt the nuclear localization. Methods: To determine if the predicted NLS is required for XA21-mediated immunityin planta, we generated transgenic plants overexpressing an XA21 variant carrying the NLS with the same alanine substitutions (Ubi-XA21nls-GFP). Results: Ubi- XA21nls-GFP plants displayed slightly longer lesion lengths, higherXoo bacterial populations after inoculation and lower levels of reactive oxygen species production compared with the Ubi- XA21-GFP control plants. However, the Ubi- XA21nls-GFP plants express lower levels of protein than that observed inUbi- XA21-GFP. Discussion: These results demonstrate that the predicted NLS is not required for XA21-mediated immunity.

  6. Association between edoxaban dose, concentration, anti-Factor Xa activity, and outcomes: an analysis of data from the randomised, double-blind ENGAGE AF-TIMI 48 trial.

    PubMed

    Ruff, Christian T; Giugliano, Robert P; Braunwald, Eugene; Morrow, David A; Murphy, Sabina A; Kuder, Julia F; Deenadayalu, Naveen; Jarolim, Petr; Betcher, Joshua; Shi, Minggao; Brown, Karen; Patel, Indravadan; Mercuri, Michele; Antman, Elliott M

    2015-06-06

    New oral anticoagulants for stroke prevention in atrial fibrillation were developed to be given in fixed doses without the need for the routine monitoring that has hindered usage and acceptance of vitamin K antagonists. A concern has emerged, however, that measurement of drug concentration or anticoagulant activity might be needed to prevent excess drug concentrations, which significantly increase bleeding risk. In the ENGAGE AF-TIMI 48 trial, higher-dose and lower-dose edoxaban were compared with warfarin in patients with atrial fibrillation. Each regimen incorporated a 50% dose reduction in patients with clinical features known to increase edoxaban drug exposure. We aim to assess whether adjustment of edoxaban dose in this trial prevented excess drug concentration and the risk of bleeding events. We analysed data from the randomised, double-blind ENGAGE AF-TIMI 48 trial. We correlated edoxaban dose, plasma concentration, and anti-Factor Xa (FXa) activity and compared efficacy and safety outcomes with warfarin stratified by dose reduction status. Patients with atrial fibrillation and at moderate to high risk of stroke were randomly assigned in a 1:1:1 ratio to receive warfarin, dose adjusted to an international normalised ratio of 2·0-3·0, higher-dose edoxaban (60 mg once daily), or lower-dose edoxaban (30 mg once daily). Randomisation was done with use of a central, 24 h, interactive, computerised response system. International normalised ratio was measured using an encrypted point-of-care device. To maintain masking, sham international normalised ratio values were generated for patients assigned to edoxaban. Edoxaban (or placebo-edoxaban in warfarin group) doses were halved at randomisation or during the trial if patients had creatinine clearance 30-50 mL/min, bodyweight 60 kg or less, or concomitant medication with potent P-glycoprotein interaction. Efficacy outcomes included the primary endpoint of all-cause stroke or systemic embolism, ischaemic stroke, and

  7. Activated partial thromboplastin time and anti-xa measurements in heparin monitoring: biochemical basis for discordance.

    PubMed

    Takemoto, Clifford M; Streiff, Michael B; Shermock, Kenneth M; Kraus, Peggy S; Chen, Junnan; Jani, Jayesh; Kickler, Thomas

    2013-04-01

    We examined the concordance of heparin levels measured by a chromogenic anti-Xa assay and the activated partial thromboplastin time (APTT) during unfractionated heparin therapy (UFH) and the biochemical basis for differences between these measures. We also investigated the endogenous thrombin potential (ETP) as a possible measure of anticoagulation. Paired measures of anti-Xa and APTT were performed on 569 samples from 149 patients on UFH. The anti-Xa values and the APTT were concordant in only 54% of measurements. One hundred twelve samples from 59 patients on UFH were assayed for APTT, anti-Xa, factor II, factor VIII, and ETP. Supratherapeutic APTT values but therapeutic anti-Xa results had decreased factor II activity. Subtherapeutic APTT but therapeutic anti-Xa values had high factor VIII activity. ETP correlated with anticoagulation status and UFH dose. In conclusion, factor II and VIII activity contributes to discordance between APTT and anti-Xa results. ETP measurements may provide an additional assessment of anticoagulation status.

  8. RUBY-1: a randomized, double-blind, placebo-controlled trial of the safety and tolerability of the novel oral factor Xa inhibitor darexaban (YM150) following acute coronary syndrome

    PubMed Central

    Steg, Ph. Gabriel; Mehta, Shamir R.; Jukema, J. Wouter; Lip, Gregory Y.H.; Gibson, C. Michael; Kovar, Frantisek; Kala, Petr; Garcia-Hernandez, Alberto; Renfurm, Ronny W.; Granger, Christopher B.

    2011-01-01

    Aims To establish the safety, tolerability and most promising regimen of darexaban (YM150), a novel, oral, direct factor Xa inhibitor, for prevention of ischaemic events in acute coronary syndrome (ACS). Methods In a 26-week, multi-centre, double-blind, randomized, parallel-group study, 1279 patients with recent high-risk non-ST-segment or ST-segment elevation ACS received one of six darexaban regimens: 5 mg b.i.d., 10 mg o.d., 15 mg b.i.d., 30 mg o.d., 30 mg b.i.d., or 60 mg o.d. or placebo, on top of dual antiplatelet treatment. Primary outcome was incidence of major or clinically relevant non-major bleeding events. The main efficacy outcome was a composite of death, stroke, myocardial infarction, systemic thromboembolism, and severe recurrent ischaemia. Results Bleeding rates were numerically higher in all darexaban arms vs. placebo (pooled HR: 2.275; 95% CI: 1.13–4.60, P = 0.022). Using placebo as reference (bleeding rate 3.1%), there was a dose–response relationship (P = 0.009) for increased bleeding with increasing darexaban dose (6.2, 6.5, and 9.3% for 10, 30, and 60 mg daily, respectively), which was statistically significant for 30 mg b.i.d. (P = 0.002). There was no decrease (indeed a numerical increase in the 30 and 60 mg dose arms) in efficacy event rates with darexaban, but the study was underpowered for efficacy. Darexaban showed good tolerability without signs of liver toxicity. Conclusions Darexaban when added to dual antiplatelet therapy after ACS produces an expected dose-related two- to four-fold increase in bleeding, with no other safety concerns but no signal of efficacy. Establishing the potential of low-dose darexaban in preventing major cardiac events after ACS requires a large phase III trial. ClinicalTrials.gov Identifier: NCT00994292 PMID:21878434

  9. Factor Xa Activation of Factor V is of Paramount Importance in Initiating the Coagulation System: Lessons from a Tick Salivary Protein

    PubMed Central

    Schuijt, Tim J.; Bakhtiari, Kamran; Daffre, Sirlei; DePonte, Kathleen; Wielders, Simone J.H.; Marquart, J. Arnoud; Hovius, Joppe W.; van der Poll, Tom; Fikrig, Erol; Bunce, Matthew W.; Camire, Rodney M.; Nicolaes, Gerry A.F.; Meijers, Joost C.M.; van 't Veer, Cornelis

    2013-01-01

    Background Generation of active procoagulant cofactor FVa and its subsequent association with the enzyme FXa to form the prothrombinase complex is a pivotal initial event in blood coagulation and has been the subject of investigative effort, speculation and controversy. The current paradigm assumes that FV activation is initiated by limited proteolysis by traces of (meizo) thrombin. Methods and Results Recombinant tick salivary protein TIX-5 was produced and anticoagulant properties were studied using plasma, whole blood and purified systems. Here we report that TIX-5 specifically inhibits FXa-mediated FV activation involving the B-domain of FV and show that FXa activation of FV is pivotal for plasma and blood clotting. In line, tick feeding is impaired on TIX-5 immune rabbits displaying the in vivo importance of TIX-5. Conclusions Our data elucidate a unique molecular mechanism by which ticks inhibit the host's coagulation system. Based on our data we propose a revised blood coagulation scheme wherein direct FXa-mediated FV activation occurs in the initiation phase during which thrombin-mediated FV activation is restrained by fibrinogen and inhibitors. PMID:23817575

  10. Monitoring of anti-Xa activity and factors related to bleeding events: A study in Japanese patients with nonvalvular atrial fibrillation receiving rivaroxaban.

    PubMed

    Sakaguchi, Teruhiro; Osanai, Hiroyuki; Murase, Yosuke; Ishii, Hideki; Nakashima, Yoshihito; Asano, Hiroshi; Suzuki, Susumu; Takefuji, Mikito; Inden, Yasuya; Sakai, Kazuyoshi; Murohara, Toyoaki; Ajioka, Masayoshi

    2017-09-01

    Anti-Xa activity (AXA) in patients with nonvalvular atrial fibrillation (NVAF) and relationship to bleeding events remains unclear. We evaluated AXA in 94 patients at both trough and peak rivaroxaban concentrations. Rivaroxaban dosage was determined according to creatinine clearance (CrCl): 10 and 15mg once daily for patients with CrCl 15-49 and CrCl ≥50mL/min, respectively. AXA value distribution and its association with bleeding events were examined in enrolled subjects. The mean peak AXA level was significantly higher than the mean trough level (1.98±0.81 vs. 0.16±0.15IU/mL; p<0.001). The peak AXA level significantly differed among patients with CrCl 15-29, 30-49, 50-79, and ≥80mL/min (2.51±0.83, 1.72±0.76, 2.05±0.82, and 1.66±0.51IU/mL, respectively; p=0.004). Major and non-major clinically relevant bleeding events occurred in 22 patients (23.4% and 14.6% per year, respectively). The mean peak AXA level was significantly higher in patients who experienced bleeding events than in those who did not (2.40±0.70 vs. 1.84±0.80IU/mL; p=0.001). A Cox multivariate analysis showed that the peak AXA level was independently related to the incidence of major and non-major clinically relevant bleeding events (p=0.012). Cumulative bleeding rates were significantly higher in patients with high peak AXA levels (p<0.001). Peak AXA level was an independent predictor for bleeding events in Japanese NVAF patients receiving rivaroxaban. Copyright © 2016 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  11. 1-[3-Aminobenzisoxazol-5'-yl]-3-trifluoromethyl-6-[2'-(3-(R)-hydroxy-N-pyrrolidinyl)methyl-[1,1']-biphen-4-yl]-1,4,5,6-tetrahydropyrazolo-[3,4-c]-pyridin-7-one (BMS-740808) a highly potent, selective, efficacious, and orally bioavailable inhibitor of blood coagulation factor Xa.

    PubMed

    Pinto, Donald J P; Orwat, Michael J; Quan, Mimi L; Han, Qi; Galemmo, Robert A; Amparo, Eugene; Wells, Brian; Ellis, Christopher; He, Ming Y; Alexander, Richard S; Rossi, Karen A; Smallwood, Angela; Wong, Pancras C; Luettgen, Joseph M; Rendina, Alan R; Knabb, Robert M; Mersinger, Lawrence; Kettner, Charles; Bai, Steven; He, Kan; Wexler, Ruth R; Lam, Patrick Y S

    2006-08-01

    Attempts to further optimize the pyrazole factor Xa inhibitors centered on masking the aryl aniline P4 moiety. Scaffold optimization resulted in the identification of a novel bicyclic pyrazolo-pyridinone scaffold which retained fXa potency. The novel bicyclic scaffold preserved all binding interactions observed with the monocyclic counterpart and importantly the carboxamido moiety was integrated within the scaffold making it less susceptible to hydrolysis. These efforts led to the identification of 1-[3-aminobenzisoxazol-5'-yl]-3-trifluoromethyl-6-[2'-(3-(R)-hydroxy-N-pyrrolidinyl)methyl-[1,1']-biphen-4-yl]-1,4,5,6-tetrahydropyrazolo-[3,4-c]-pyridin-7-one 6f (BMS-740808), a highly potent (fXa Ki=30 pM) with a rapid onset of inhibition (2.7x10(7) M-1 s-1) in vitro, selective (>1000-fold over other proteases), efficacious in the AVShunt thrombosis model, and orally bioavailable inhibitor of blood coagulation factor Xa.

  12. A Novel Direct Factor Xa Inhibitory Peptide with Anti-Platelet Aggregation Activity from Agkistrodon acutus Venom Hydrolysates

    PubMed Central

    Chen, Meimei; Ye, Xiaohui; Ming, Xin; Chen, Yahui; Wang, Ying; Su, Xingli; Su, Wen; Kong, Yi

    2015-01-01

    Snake venom is a natural substance that contains numerous bioactive proteins and peptides, nearly all of which have been identified over the last several decades. In this study, we subjected snake venom to enzymatic hydrolysis to identify previously unreported bioactive peptides. The novel peptide ACH-11 with the sequence LTFPRIVFVLG was identified with both FXa inhibition and anti-platelet aggregation activities. ACH-11 inhibited the catalytic function of FXa towards its substrate S-2222 via a mixed model with a Ki value of 9.02 μM and inhibited platelet aggregation induced by ADP and U46619 in a dose-dependent manner. Furthermore, ACH-11 exhibited potent antithrombotic activity in vivo. It reduced paralysis and death in an acute pulmonary thrombosis model by 90% and attenuated thrombosis weight in an arterio-venous shunt thrombosis model by 57.91%, both at a dose of 3 mg/kg. Additionally, a tail cutting bleeding time assay revealed that ACH-11 did not prolong bleeding time in mice at a dose of 3 mg/kg. Together, our results reveal that ACH-11 is a novel antithrombotic peptide exhibiting both FXa inhibition and anti-platelet aggregation activities, with a low bleeding risk. We believe that it could be a candidate or lead compound for new antithrombotic drug development. PMID:26035670

  13. CD-XA Reusable Launch Vehicle (RLV)

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This is the McDornell Douglas CD-XA Reusable Launch Vehicle (RLV) concept. The Delta Clipper-Experimental (DC-X) was originally developed by McDonnell Douglas for the DOD. The DC-XA is a single-stage-to-orbit, vertical takeoff/vertical landing, launch vehicle concept, whose development is geared to significantly reduce launch cost and provided a test bed for NASA Reusable Launch Vehicle (RLV) technology as the Delta Clipper-Experimental Advanced (DC-XA). The program was discontinued in 2003.

  14. Molecular phylogeny, homology modeling, and molecular dynamics simulation of race-specific bacterial blight disease resistance protein (xa5) of rice: a comparative agriproteomics approach.

    PubMed

    Dehury, Budheswar; Sahu, Mousumi; Sarma, Kishore; Sahu, Jagajjit; Sen, Priyabrata; Modi, Mahendra Kumar; Sharma, Gauri Dutta; Choudhury, Manabendra Dutta; Barooah, Madhumita

    2013-08-01

    Rice (Oryza sativa L.), a model plant belonging to the family Poaceae, is a staple food for a majority of the people worldwide. Grown in the tropical and subtropical regions of the world, this important cereal crop is under constant and serious threat from both biotic and abiotic stresses. Among the biotic threats, Xanthomonas oryzae pv. oryzae, causing the damaging bacterial blight disease in rice, is a prominent pathogen. The xa5 gene in the host plant rice confers race-specific resistance to this pathogen. This recessive gene belongs to the Xa gene family of rice and encodes a gamma subunit of transcription factor IIA (TFIIAγ). In view of the importance of this gene in conferring resistance to the devastating disease, we reconstructed the phylogenetic relationship of this gene, developed a three-dimensional protein model, followed by long-term molecular dynamics simulation studies to gain a better understanding of the evolution, structure, and function of xa5. The modeled structure was found to fit well with the small subunit of TFIIA from human, suggesting that it may also act as a small subunit of TFIIA in rice. The model had a stable conformation in response to the atomic flexibility and interaction, when subjected to MD simulation at 20 nano second in aqueous solution. Further structural analysis of xa5 indicated that the protein retained its basic transcription factor function, suggesting that it might govern a novel pathway responsible for bacterial blight resistance. Future molecular docking studies of xa5 underway with its corresponding avirulence gene is expected to shed more direct light into plant-pathogen interactions at the molecular level and thus pave the way for richer agriproteomic insights.

  15. Discovery of a factor Xa inhibitor (3R,4R)-1-(2,2-difluoro-ethyl)-pyrrolidine-3,4-dicarboxylic acid 3-[(5-chloro-pyridin-2-yl)-amide] 4-[[2-fluoro-4-(2-oxo-2H-pyridin-1-yl)-phenyl]-amide] as a clinical candidate.

    PubMed

    Anselm, Lilli; Banner, David W; Benz, Jörg; Zbinden, Katrin Groebke; Himber, Jacques; Hilpert, Hans; Huber, Walter; Kuhn, Bernd; Mary, Jean-Luc; Otteneder, Michael B; Panday, Narendra; Ricklin, Fabienne; Stahl, Martin; Thomi, Stefan; Haap, Wolfgang

    2010-09-01

    A series of (3R,4R)-pyrrolidine-3,4-dicarboxylic acid amides was investigated with respect to their factor Xa inhibitory activity, selectivity, pharmacokinetic properties, and ex vivo antithrombotic activity. The clinical candidate from this series, R1663, exhibits excellent selectivity against a panel of serine proteases and good pharmacokinetic properties in rats and monkeys. A Phase I clinical study with R1663 has been finalized. Copyright 2010 Elsevier Ltd. All rights reserved.

  16. 5-Chlorothiophene-2-carboxylic acid [(S)-2-[2-methyl-3-(2-oxopyrrolidin-1-yl)benzenesulfonylamino]-3-(4-methylpiperazin-1-yl)-3-oxopropyl]amide (SAR107375), a selective and potent orally active dual thrombin and factor Xa inhibitor.

    PubMed

    Meneyrol, Jerome; Follmann, Markus; Lassalle, Gilbert; Wehner, Volkmar; Barre, Guillaume; Rousseaux, Tristan; Altenburger, Jean-Michel; Petit, Frederic; Bocskei, Zsolt; Schreuder, Herman; Alet, Nathalie; Herault, Jean-Pascal; Millet, Laurence; Dol, Frederique; Florian, Peter; Schaeffer, Paul; Sadoun, Freddy; Klieber, Sylvie; Briot, Christophe; Bono, Françoise; Herbert, Jean-Marc

    2013-12-12

    Compound 15 (SAR107375), a novel potent dual thrombin and factor Xa inhibitor resulted from a rational optimization process. Starting from compound 14, with low factor Xa and modest anti-thrombin inhibitory activities (IC50's of 3.5 and 0.39 μM, respectively), both activities were considerably improved, notably through the incorporation of a neutral chlorothiophene P1 fragment and tuning of P2 and P3-P4 fragments. Final optimization of metabolic stability with microsomes led to the identification of 15, which displays strong activity in vitro vs factor Xa and thrombin (with Ki's of 1 and 8 nM, respectively). In addition 15 presents good selectivity versus related serine proteases (roughly 300-fold), including trypsin (1000-fold), and is very active (0.39 μM) in the thrombin generation time (TGT) coagulation assay in human platelet rich plasma (PRP). Potent in vivo activity in a rat model of venous thrombosis following iv and, more importantly, po administration was also observed (ED50 of 0.07 and 2.8 mg/kg, respectively). Bleeding liability was reduced in the rat wire coil model, more relevant to arterial thrombosis, with 15 (blood loss increase of 2-fold relative to the ED80 value) compared to rivaroxaban 2 and dabigatran etexilate 1a.

  17. Accuracy and consistency of anti-Xa activity measurement for determination of rivaroxaban plasma levels.

    PubMed

    Studt, J-D; Alberio, L; Angelillo-Scherrer, A; Asmis, L M; Fontana, P; Korte, W; Mendez, A; Schmid, P; Stricker, H; Tsakiris, D A; Wuillemin, W A; Nagler, M

    2017-08-01

    Essentials Accurate determination of anticoagulant plasma concentration is important in clinical practice. We studied the accuracy and consistency of anti-Xa assays for rivaroxaban in a multicentre study. In a range between 50 and 200 μg L(-1) , anti-Xa activity correlated well with plasma concentrations. The clinical value might be limited by overestimation and intra- and inter-individual variation. Background Determining the plasma level of direct oral anticoagulants reliably is important in the work-up of complex clinical situations. Objectives To study the accuracy and consistency of anti-Xa assays for rivaroxaban plasma concentration in a prospective, multicenter evaluation study employing different reagents and analytical platforms. Methods Rivaroxaban 20 mg was administered once daily to 20 healthy volunteers and blood samples were taken at peak and trough levels (clinicaltrials.gov NCT01710267). Anti-Xa activity was determined in 10 major laboratories using different reagents and analyzers; corresponding rivaroxaban plasma concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Findings Overall Pearson's correlation coefficient of anti-Xa levels and HPLC-MS results was 0.99 for Biophen(®) Heparin (95% CI, 0.99, 0.99), Biophen(®) DiXaI (95% CI, 0.99, 0.99) and STA(®) anti-Xa liquid (95% CI, 0.99, 1.00). Correlation was lower in rivaroxaban concentrations below 50 μg L(-1) and above 200 μg L(-1) . The overall bias of the Bland-Altman difference plot was 14.7 μg L(-1) for Biophen Heparin, 17.9 μg L(-1) for Biophen DiXal and 19.0 μg L(-1) for STA anti-Xa liquid. Agreement between laboratories was high at peak level but limited at trough level. Conclusions Anti-Xa activity correlated well with rivaroxaban plasma concentrations, especially in a range between 50 and 200 μg L(-1) . However, anti-Xa assays systematically overestimated rivaroxaban concentration as compared with HPLC

  18. Discovery of 1-(4-Methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro- 1H-pyrazolo[3,4-c]pyridine-3-carboxamide (Apixaban, BMS-562247), a Highly Potent, Selective, Efficacious, and Orally Bioavailable Inhibitor of Blood Coagulation Factor Xa

    SciTech Connect

    Pinto, Donald J.P.; Orwat, Michael J.; Koch, Stephanie; Rossi, Karen A.; Alexander, Richard S.; Smallwood, Angela; Wong, Pancras C.; Rendina, Alan R.; Luettgen, Joseph M.; Knabb, Robert M.; He, Kan; Xin, Baomin; Wexler, Ruth R.; Lam, Patrick Y.S.

    2010-03-08

    Efforts to identify a suitable follow-on compound to razaxaban (compound 4) focused on modification of the carboxamido linker to eliminate potential in vivo hydrolysis to a primary aniline. Cyclization of the carboxamido linker to the novel bicyclic tetrahydropyrazolopyridinone scaffold retained the potent fXa binding activity. Exceptional potency of the series prompted an investigation of the neutral P{sub 1} moieties that resulted in the identification of the p-methoxyphenyl P{sub 1}, which retained factor Xa binding affinity and good oral bioavailability. Further optimization of the C-3 pyrazole position and replacement of the terminal P{sub 4} ring with a neutral heterocycle culminated in the discovery of 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide (apixaban, compound 40). Compound 40 exhibits a high degree of fXa potency, selectivity, and efficacy and has an improved pharmacokinetic profile relative to 4.

  19. DOUGLAS XA3D-1 #413 AIRPLANE.

    NASA Image and Video Library

    1955-07-27

    DOUGLAS XA3D-1 #413 AIRPLANE MOUNTED IN THE NACA AMES RESEARCH CENTER'S 40X80_FOOT SUBSONIC WIND TUNNEL Testing the boundary layer control of the A3D in the 40 x 80 wind tunnel. Boundary layer control was added to increase the lift of the wing for take off from an aircraft carrier.

  20. DOUGLAS XA3D-1 #413 AIRPLANE.

    NASA Image and Video Library

    1955-07-27

    DOUGLAS XA3D-1 #413 AIRPLANE MOUNTED IN THE NACA AMES RESEARCH CENTER'S 40X80_FOOT SUBSONIC WIND TUNNEL sweptback wing Testing the wing boundary layer control of the A3D in the 40 x 80 wind tunnel. Boundary layer control was added to increase the lift of the wing for aircraft carrier take off and landing.

  1. Clinical decision-making for vitamin K-1 and K-2 deficiency and coronary artery calcification with warfarin therapy: are diet, factor Xa inhibitors or both the answer?

    PubMed

    Wahlqvist, Mark L; Tanaka, Kiyoshi; Tzeng, Bing-Hsiean

    2013-01-01

    Coronary artery calcification is a recognised risk factor for ischaemic heart disease and mortality. Evidence is now strong that Mönckeberg's arteriosclerosis, a form of vascular calcification, can be attributable to vitamin K deficiency, but that vitamin K-2, especially the MK-4 form from foods like cheese can be protective. Warfarin blocks the recycling of hepatic and peripheral vitamin K leading to secondary vitamin K deficiency with adverse effects on vasculature, bone, kidneys, brain and other tissues and systems (inflammatory, immune function and neoplasia at least). There is individual susceptibility to vitamin K deficiency and warfarin sensitivity, partly explicable in terms of genetic polymorphisms, epigenetics, diet and pharmacotherapy. The emergence of extensive coronary calcification in a man with atrial fibrillation treated for a decade with warfarin is described by way of illustration and to raise the present clinical management conundrums. Finally, a putative set of recommendations is provided.

  2. High-resolution genetic mapping of rice bacterial blight resistance gene Xa23.

    PubMed

    Wang, Chunlian; Fan, Yinglun; Zheng, Chongke; Qin, Tengfei; Zhang, Xiaoping; Zhao, Kaijun

    2014-10-01

    Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating bacterial disease of rice (Oryza sativa L.), a staple food crop that feeds half of the world's population. In management of this disease, the most economical and effective approach is cultivating resistant varieties. Due to rapid change of pathogenicity in the pathogen, it is necessary to identify and characterize more host resistance genes for breeding new resistant varieties. We have previously identified the BB resistance (R) gene Xa23 that confers the broadest resistance to Xoo strains isolated from different rice-growing regions and preliminarily mapped the gene within a 1.7 cm region on the long arm of rice chromosome 11. Here, we report fine genetic mapping and in silico analysis of putative candidate genes of Xa23. Based on F2 mapping populations derived from crosses between Xa23-containing rice line CBB23 and susceptible varieties JG30 or IR24, six new STS markers Lj36, Lj46, Lj138, Lj74, A83B4, and Lj13 were developed. Linkage analysis revealed that the new markers were co-segregated with or closely linked to the Xa23 locus. Consequently, the Xa23 gene was mapped within a 0.4 cm region between markers Lj138 and A83B4, in which the co-segregating marker Lj74 was identified. The corresponding physical distance between Lj138 and A83B4 on Nipponbare genome is 49.8 kb. Six Xa23 candidate genes have been annotated, including four candidate genes encoding hypothetical proteins and the other two encoding a putative ADP-ribosylation factor protein and a putative PPR protein. These results will facilitate marker-assisted selection of Xa23 in rice breeding and molecular cloning of this valuable R gene.

  3. Mox: a novel modifier of the tomato Xa locus.

    PubMed

    Peterson, P W; Yoder, J I

    1995-01-01

    We have isolated a novel mutation that caused variegated leaf color in a tomato plant which had multiple maize Ac transposable elements and the tomato Xa allele. Xa is a previously characterized semi-dominant mutation that causes tomato leaves to be bright yellow when heterozygous (Xa/xa+). The mutation responsible for the new phenotype was named Mox (Modifier of Xa). The Mox mutation modified the Xa/xa+ yellow leaf phenotype in two ways: it compensated for the Xa allele resulting in a plant with a wildtype green color, and it caused somatic variegation which appeared as white and yellow sectors on the green background. Somatic variegation was visible only if the plant contained both the Mox and Xa loci. Genetic studies indicated that the Mox locus was linked in repulsion to Xa and that the Mox locus was genetically transmitted at a reduced frequency through the male gamete. Molecular characterization of the Ac elements in lines segregating for Mox identified an Ac insertion that appeared to cosegregate with Mox variegation. We propose a model in which the Mox mutation consists of a duplication of the xa+ allele and subsequent Ac-induced breakage of the duplicated region causes variegation.

  4. Antifactor Xa levels versus activated partial thromboplastin time for monitoring unfractionated heparin.

    PubMed

    Vandiver, Jeremy W; Vondracek, Thomas G

    2012-06-01

    Intravenous unfractionated heparin (UFH) remains an important therapeutic agent, particularly in the inpatient setting, for anticoagulation. Historically, the activated partial thromboplastin time (aPTT) has been the primary laboratory test used to monitor and adjust UFH. The aPTT test has evolved since the 1950s, and the historical goal range of 1.5-2.5 times the control aPTT, which first gained favor in the 1970s, has fallen out of favor due to a high degree of variability in aPTT readings from one laboratory to another, and even from one reagent to another. As a result, it is now recommended that the aPTT goal range be based on a corresponding heparin concentration of 0.2-0.4 unit/ml by protamine titration or 0.3-0.7 unit/ml by antifactor Xa assay. Given that several biologic factors can influence the aPTT independent of the effects of UFH, many institutions have transitioned to monitoring heparin with antifactor Xa levels, rather than the aPTT. Clinical data from the last 10-20 years have begun to show that a conversion from aPTT to antifactor Xa monitoring may offer a smoother dose-response curve, such that levels remain more stable, requiring fewer blood samples and dosage adjustments. Given the minimal increased acquisition cost of the antifactor Xa reagents, it can be argued that the antifactor Xa is a cost-effective method for monitoring UFH. In this review, we discuss the relative advantages and disadvantages of the aPTT, antifactor Xa, and protamine titration tests, and provide a clinical framework to guide practitioners who are seeking to optimize UFH monitoring within their own institutions.

  5. Identifying direct protective factors for nonviolence.

    PubMed

    Pardini, Dustin A; Loeber, Rolf; Farrington, David P; Stouthamer-Loeber, Magda

    2012-08-01

    The CDC recently organized a panel to examine whether a series of constructs consistently acted as risk and/or direct protective factors for youth violence across four longitudinal studies. Analyses first examined constructs commonly assessed across all four studies and then included constructs unique to each study. This paper describes findings from the Pittsburgh Youth Study (PYS) as part of this supplement to the American Journal of Preventive Medicine documenting the findings from the project. Participants were boys in the youngest cohort of the PYS (N=503), which was initiated in 1987-1988. Constructs measured at age 12 years were trichotomized to test whether they acted as risk and/or direct protective factors in predicting violence (i.e., assault, rape, robbery) across ages 13-14 years and 15-18 years. Multivariate logistic regressions with predictors present across studies indicated that depressed mood (OR=1.96) and low religious observance (OR=1.88) were risk factors for violence at ages 13-14 years, whereas peer delinquency acted as both a risk (OR=2.34) and direct protective factor (OR=0.44). Low peer delinquency was also a direct protective factor (OR=0.41) for violence at ages 15-18 years. Analyses including predictors specific to the PYS indicated that negative attitude toward delinquency (OR=0.50) was protective against violence at ages 13-14 years, whereas the risk factors of low perceived likelihood of being caught (OR=1.81) and high neighborhood disorder/crime (OR=1.77) predicted violence at ages 15-18 years. Some factors may be best conceptualized as direct protective factors for nonviolence, whereas other constructs act primarily as risk factors that increase the probability of adolescent violence. Copyright © 2012 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  6. Draft Genome Sequence of Enterobacter cloacae subsp. cloacae Strain 08XA1, a Fecal Bacterium of Giant Pandas

    PubMed Central

    Yan, Yue; Zhao, Chuan-Wu; Zhang, Yi-Zheng; Zhang, Zhi-He; Pan, Guang-Lin; Liu, Wen-Wang; Ma, Qing-Yi; Hou, Rong

    2012-01-01

    Enterobacter cloacae, a common pathogenic bacterium, is a Gram-negative bacillus. We analyzed the draft genome of Enterobacter cloacae subsp. cloacae strain 08XA1 from the feces of a giant panda in China. Genes encoding a β-lactamase and efflux pumps, as well as other factors, have been found in the genome. PMID:23209197

  7. Determination of rivaroxaban in patient’s plasma samples by anti-Xa chromogenic test associated to High Performance Liquid Chromatography tandem Mass Spectrometry (HPLC-MS/MS)

    PubMed Central

    Derogis, Priscilla Bento Matos; Sanches, Livia Rentas; de Aranda, Valdir Fernandes; Colombini, Marjorie Paris; Mangueira, Cristóvão Luis Pitangueira; Katz, Marcelo; Faulhaber, Adriana Caschera Leme; Mendes, Claudio Ernesto Albers; Ferreira, Carlos Eduardo dos Santos; França, Carolina Nunes; Guerra, João Carlos de Campos

    2017-01-01

    Rivaroxaban is an oral direct factor Xa inhibitor, therapeutically indicated in the treatment of thromboembolic diseases. As other new oral anticoagulants, routine monitoring of rivaroxaban is not necessary, but important in some clinical circumstances. In our study a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was validated to measure rivaroxaban plasmatic concentration. Our method used a simple sample preparation, protein precipitation, and a fast chromatographic run. It was developed a precise and accurate method, with a linear range from 2 to 500 ng/mL, and a lower limit of quantification of 4 pg on column. The new method was compared to a reference method (anti-factor Xa activity) and both presented a good correlation (r = 0.98, p < 0.001). In addition, we validated hemolytic, icteric or lipemic plasma samples for rivaroxaban measurement by HPLC-MS/MS without interferences. The chromogenic and HPLC-MS/MS methods were highly correlated and should be used as clinical tools for drug monitoring. The method was applied successfully in a group of 49 real-life patients, which allowed an accurate determination of rivaroxaban in peak and trough levels. PMID:28170419

  8. Determination of rivaroxaban in patient's plasma samples by anti-Xa chromogenic test associated to High Performance Liquid Chromatography tandem Mass Spectrometry (HPLC-MS/MS).

    PubMed

    Derogis, Priscilla Bento Matos; Sanches, Livia Rentas; de Aranda, Valdir Fernandes; Colombini, Marjorie Paris; Mangueira, Cristóvão Luis Pitangueira; Katz, Marcelo; Faulhaber, Adriana Caschera Leme; Mendes, Claudio Ernesto Albers; Ferreira, Carlos Eduardo Dos Santos; França, Carolina Nunes; Guerra, João Carlos de Campos

    2017-01-01

    Rivaroxaban is an oral direct factor Xa inhibitor, therapeutically indicated in the treatment of thromboembolic diseases. As other new oral anticoagulants, routine monitoring of rivaroxaban is not necessary, but important in some clinical circumstances. In our study a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was validated to measure rivaroxaban plasmatic concentration. Our method used a simple sample preparation, protein precipitation, and a fast chromatographic run. It was developed a precise and accurate method, with a linear range from 2 to 500 ng/mL, and a lower limit of quantification of 4 pg on column. The new method was compared to a reference method (anti-factor Xa activity) and both presented a good correlation (r = 0.98, p < 0.001). In addition, we validated hemolytic, icteric or lipemic plasma samples for rivaroxaban measurement by HPLC-MS/MS without interferences. The chromogenic and HPLC-MS/MS methods were highly correlated and should be used as clinical tools for drug monitoring. The method was applied successfully in a group of 49 real-life patients, which allowed an accurate determination of rivaroxaban in peak and trough levels.

  9. Marker-aided Incorporation of Xa38, a Novel Bacterial Blight Resistance Gene, in PB1121 and Comparison of its Resistance Spectrum with xa13 + Xa21.

    PubMed

    Ellur, Ranjith K; Khanna, Apurva; S, Gopala Krishnan; Bhowmick, Prolay K; Vinod, K K; Nagarajan, M; Mondal, Kalyan K; Singh, Nagendra K; Singh, Kuldeep; Prabhu, Kumble Vinod; Singh, Ashok K

    2016-07-11

    Basmati rice is preferred internationally because of its appealing taste, mouth feel and aroma. Pusa Basmati 1121 (PB1121) is a widely grown variety known for its excellent grain and cooking quality in the international and domestic market. It contributes approximately USD 3 billion to India's forex earning annually by being the most traded variety. However, PB1121 is highly susceptible to bacterial blight (BB) disease. A novel BB resistance gene Xa38 was incorporated in PB1121 from donor parent PR114-Xa38 using a modified marker-assisted backcross breeding (MABB) scheme. Phenotypic selection prior to background selection was instrumental in identifying the novel recombinants with maximum recovery of recurrent parent phenome. The strategy was effective in delimiting the linkage drag to <0.5 mb upstream and <1.9 mb downstream of Xa38 with recurrent parent genome recovery upto 96.9% in the developed NILs. The NILs of PB1121 carrying Xa38 were compared with PB1121 NILs carrying xa13 + Xa21 (developed earlier in our lab) for their resistance to BB. Both NILs showed resistance against the Xoo races 1, 2, 3 and 6. Additionally, Xa38 also resisted Xoo race 5 to which xa13 + Xa21 was susceptible. The PB1121 NILs carrying Xa38 gene will provide effective control of BB in the Basmati growing region.

  10. Marker-aided Incorporation of Xa38, a Novel Bacterial Blight Resistance Gene, in PB1121 and Comparison of its Resistance Spectrum with xa13 + Xa21

    PubMed Central

    Ellur, Ranjith K.; Khanna, Apurva; S, Gopala Krishnan.; Bhowmick, Prolay K.; Vinod, K. K.; Nagarajan, M.; Mondal, Kalyan K.; Singh, Nagendra K.; Singh, Kuldeep; Prabhu, Kumble Vinod; Singh, Ashok K.

    2016-01-01

    Basmati rice is preferred internationally because of its appealing taste, mouth feel and aroma. Pusa Basmati 1121 (PB1121) is a widely grown variety known for its excellent grain and cooking quality in the international and domestic market. It contributes approximately USD 3 billion to India’s forex earning annually by being the most traded variety. However, PB1121 is highly susceptible to bacterial blight (BB) disease. A novel BB resistance gene Xa38 was incorporated in PB1121 from donor parent PR114-Xa38 using a modified marker-assisted backcross breeding (MABB) scheme. Phenotypic selection prior to background selection was instrumental in identifying the novel recombinants with maximum recovery of recurrent parent phenome. The strategy was effective in delimiting the linkage drag to <0.5 mb upstream and <1.9 mb downstream of Xa38 with recurrent parent genome recovery upto 96.9% in the developed NILs. The NILs of PB1121 carrying Xa38 were compared with PB1121 NILs carrying xa13 + Xa21 (developed earlier in our lab) for their resistance to BB. Both NILs showed resistance against the Xoo races 1, 2, 3 and 6. Additionally, Xa38 also resisted Xoo race 5 to which xa13 + Xa21 was susceptible. The PB1121 NILs carrying Xa38 gene will provide effective control of BB in the Basmati growing region. PMID:27403778

  11. Hemofiltration during cardiopulmonary bypass: the effect on anti-Xa and anti-IIa heparin activity.

    PubMed

    Despotis, G J; Levine, V; Filos, K S; Joiner-Maier, D; Joist, J H

    1997-03-01

    Previous studies have demonstrated that heparin concentrations during cardiopulmonary bypass (CPB) may vary considerably, which may be related to variability in redistribution, cellular and plasma protein binding, and clearance of heparin. The purpose of this study was to determine whether hemofiltration removes lower molecular weight fractions of heparin from plasma and thus contributes to variability of blood levels of heparin. Twenty patients undergoing cardiac surgery with CPB were enrolled in this study after informed consent was obtained. The study was subdivided into two phases. The first 10 patients were enrolled in Phase I, which was designed to determine whether hemofiltration removes lower molecular weight fractions of heparin from blood. Blood specimens obtained from the inflow line and outflow lines of the hemofiltration unit were used to measure complete blood counts (CBC) and plasma heparin activity by anti-Xa and anti-IIa assays. Phase II was designed to evaluate the effect of hemofiltration on circulating plasma heparin activity. In Phase II, blood specimens were obtained from 10 patients via the arterial cannula of the extracorporeal circuit prior to and after hemofiltration for measurements of CBCs, anti-Xa plasma heparin, as well as whole blood heparin concentration using an automated protamine titration assay (Hepcon instrument, Medtronic Inc., Parker, CO). Ultrafiltrate and reservoir volumes were measured in both phases of the study. Hemofiltration did not remove lower (anti-Xa measurable) molecular weight heparin, but it resulted in a considerable increase in heparin activity in the outflow line, as measured by both anti-Xa and anti-IIa assays. The plasma anti-Xa heparin activity obtained after hemofiltration (5 +/- 1.8 U/mL) was substantially (P = 0.003) greater than heparin activity obtained prior to hemofiltration (3.9 +/- 1.7 U/mL). The increase in heparin activity with hemofiltration was directly related to ultrafiltrate volume (r = 0

  12. [Antidotes to novel direct oral anticoagulants].

    PubMed

    Khorev, N G; Momot, A P; Kon'kova, V O

    During the last 10 years, several novel direct oral anticoagulants (NOACs) have entered the clinical arena and were registered in the Russian Federation for use in patients presenting with atrial fibrillation, venous thrombosis, and pulmonary artery thromboembolism. NOACs are classified into two groups: direct thrombin inhibitor (notably dabigatran) and factor Xa inhibitors (including rivaroxaban, apixaban, and edoxaban). Their disadvantage is lack of specific antidotes in case of an emergency situation (injury, infarction, stroke requiring thrombolysis, urgent operation). The review contains the data on the existing therapeutic regimens of treating haemorrhage on the background of taking these coagulants. This is followed by analysing the present-day results of clinical trials aimed at working out pharmaceutical agents (andexanet alpha, idarucizumab, aripazine) being antidotes to direct thrombin inhibitor and the factor Xa inhibitors. Administration of these agents makes it possible to reverse coagulation and minimize the aftermaths of haemorrhage in patients taking these drugs, in emergency situations.

  13. Extracting spectroscopic factors from direct reactions

    NASA Astrophysics Data System (ADS)

    Jones, Kate

    2009-10-01

    Direct reactions have been used to probe the structure of the nucleus for decades. After some decline in the 80's and 90's these methods have more recently had a surge in popularity, and new techniques have been added to the experimentalists toolbox. One goal of direct reaction experiments is to extract spectroscopic factors (SFs), related to the shell occupancy. SFs extracted from neutron knockout reactions show reductions, compared to the theoretical value, that are related to the neutron separation energy [1], whereas SFs from the well-established (e,e'p) reaction on stable nuclei are consistently 50% - 60% lower than those expected from the independent-particle shell model [2] over a wide range of masses. pardAs the extraction of spectroscopic factors from direct reaction measurements requires the comparison of data with calculated differential cross sections, the results are by nature model dependent. The influence of different scattering (commonly optical), and bound state potentials, should not be over-looked. Recent attempts to reanalyze single-neutron transfer data using a consistent approach have shown agreement with large basis shell model calculations [3], clearly conflicting with both the (e,e'p) and the knockout data. It has been suggested that the Asymptotic Normalization Coefficient (ANC) is a more valid quantity to extract when the reaction is peripheral [4]. spectroscopic factors are, how they are extracted and what they really mean will be discussed in this talk.[4pt] [1] Alexandra Gade, and Thomas Glasmacher, Prog Part. Nucl. Phys. 60 (2008) 161-224.[0pt] [2] G.J. Kramer, H.P. Blok, and L. Lapik'as, Nucl. Phys. A679 (2001) 267-286.[0pt] [3] Jenny Lee, M.B. Tsang, and W.G. Lynch, Phys. Rev C 75, (2007), 064320.[0pt] [4] D.Y. Pan, F.M. Nunes, and A.M. Mukhamedzhanov, Phys. Rev. C 75, (2007) 024601.

  14. Human Factors Directions for Civil Aviation

    NASA Technical Reports Server (NTRS)

    Hart, Sandra G.

    2002-01-01

    Despite considerable progress in understanding human capabilities and limitations, incorporating human factors into aircraft design, operation, and certification, and the emergence of new technologies designed to reduce workload and enhance human performance in the system, most aviation accidents still involve human errors. Such errors occur as a direct or indirect result of untimely, inappropriate, or erroneous actions (or inactions) by apparently well-trained and experienced pilots, controllers, and maintainers. The field of human factors has solved many of the more tractable problems related to simple ergonomics, cockpit layout, symbology, and so on. We have learned much about the relationships between people and machines, but know less about how to form successful partnerships between humans and the information technologies that are beginning to play a central role in aviation. Significant changes envisioned in the structure of the airspace, pilots and controllers' roles and responsibilities, and air/ground technologies will require a similarly significant investment in human factors during the next few decades to ensure the effective integration of pilots, controllers, dispatchers, and maintainers into the new system. Many of the topics that will be addressed are not new because progress in crucial areas, such as eliminating human error, has been slow. A multidisciplinary approach that capitalizes upon human studies and new classes of information, computational models, intelligent analytical tools, and close collaborations with organizations that build, operate, and regulate aviation technology will ensure that the field of human factors meets the challenge.

  15. Induction of Xa10-like Genes in Rice Cultivar Nipponbare Confers Disease Resistance to Rice Bacterial Blight.

    PubMed

    Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao

    2017-06-01

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice-growing regions in the world. The rice disease resistance (R) gene Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effector AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. 'Nipponbare' rice carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from 'CBB23' rice. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here, we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALE). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino-acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni, and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic reticulum (ER) membrane

  16. In vivo 3D reconstruction of human vertebrae with the three-dimensional X-ray absorptiometry (3D-XA) method.

    PubMed

    Kolta, S; Quiligotti, S; Ruyssen-Witrand, A; Amido, A; Mitton, D; Bras, A Le; Skalli, W; Roux, C

    2008-02-01

    We used a standard DXA device equipped with a C-arm to do in vivo reconstruction of human vertebrae from two orthogonal scans. This new technique, called 3D-XA (three-dimensional X-ray absorptiometry), allows the direct measurement of geometric parameters of the vertebrae with a good accuracy and precision. Geometric parameters are predictors of bone strength. A technique called three-dimensional X-ray absorptiometry (3D-XA) allows 3D reconstruction of bones from DXA scans. We used the 3D-XA method to reconstruct human vertebrae and to evaluate the method's in vitro accuracy and in vivo precision. A standard DXA device equipped with a C-arm was used. Calibration of its environment and identification of different anatomical landmarks of the vertebrae allows personalized 3D geometric reconstruction of vertebrae. Accuracy was calculated by reconstructing 16 dry human vertebrae by 3D-XA and CT scanner. In vivo inter-observer precision was calculated using 20 human spines. The mean difference between 3D reconstruction by CT and 3D-XA was -0.2 +/- 1.3 mm. The in vivo mean difference of the 3D-XA method between the two rheumatologists was -0.1 +/- 0.8 mm. For geometric parameters, mean difference ranged from 0.4 to 0.9 mm. For cross-sectional area and vertebral body volume, it was 2.9% and 3.2%, respectively. This study shows the good accuracy and precision of 3D-XA using a standard DXA device. It yields complementary information on bone geometry. Further studies are needed to evaluate if, coupled with bone density, it improves vertebral fracture risk prediction.

  17. Directional intercept factor of truncated CPCs

    SciTech Connect

    Minano, J.C.

    1983-09-01

    The fraction of power reaching the collector of a truncated cylindrical compound parabolic concentrator, out of the total power arriving at its entry aperture in a given direction, is calculated without ray tracing for all directions.

  18. RGS Spectroscopy of the Cygnus Loop XA Knot

    NASA Technical Reports Server (NTRS)

    Gaetz, Terrance J.; Mushotzky, Richard F. (Technical Monitor)

    2003-01-01

    The observations were performed at the end of April 2002, and the data were received in July 2002. Unfortunately, the observations were badly compromised by high levels of background radiation; one the three observations lost entirely. Two replacement observations were scheduled for November 2002, and were only made available in January of 2003. Consequently, we have had little time to grapple with the unusual data analysis challenges. The search for a postdoctoral fellow has been successfully concluded, and Manami Sasaki began working for us in January 2003. She will be supported in part by these funds, and will be working to help understand these data. Examination of the RGS 'Orders' images indicate the presence of broad emission lines (as expected for the diffuse XA knot). However, examination of the 'Spatial' dispersion/cross-dispersion images indicate that the emission is also broad in the cross-dispersion direction. (As a crosscheck, some of the 'Lockman Hole' datasets were also examined as representative 'sky background' datasets; in these, both types of images are relatively flat (outside the calibration source regions). The quicklook plots of the spectra show the expected O VII and O VIII lines, in addition to a complex around 35 Angstroms; the approx. 35 Angstrom line is likely the C V He-beta line at 34.97 Angstrom, but identifying the additional line(s) will require a more careful reduction of the data. Consequently, there is valuable information to be extracted from these data, but it is complicated by diffuse nature of the emission. Because the angular scale is large, we will have to make use of sky background datasets in order to do the background fitting. A color composite image of OM data in the three UV bands was presented at the 'How does the Galaxy Work?' meeting, and compared to optical and X-ray imaging data. Quantitative analysis will require obtaining the effective bandpasses of the UV filters so that the predominant line and continuum

  19. The broadly effective recessive resistance gene xa5 of rice is a virulence effector-dependent quantitative trait for bacterial blight.

    PubMed

    Huang, Sheng; Antony, Ginny; Li, Ting; Liu, Bo; Obasa, Ken; Yang, Bing; White, Frank F

    2016-04-01

    Mutations in disease susceptibility (S) genes, here referred to as recessive resistance genes, have promise for providing broad durable resistance in crop species. However, few recessive disease resistance genes have been characterized. Here, we show that the broadly effective resistance gene xa5,for resistance to bacterial blight of rice (Oryza sativa), is dependent on the effector genes present in the pathogen. Specifically, the effectiveness of xa5 in preventing disease by strains of Xanthomonas oryzae pv. oryzae is dependent on major transcription activation-like (TAL) effector genes, and correlates with reduced expression of the cognate S genes. xa5 is ineffective in preventing disease by strains containing the TAL effector gene pthXo1, which directs robust expression of the S gene OsSWEET11, a member of sucrose transporter gene family. Incompatibility is associated with major TAL effectors that target the known alternative S genes OsSWEET14 and OsSWEET13. Incompatibility is defeated by transfer of pthXo1 to otherwise xa5-incompatible strains or by engineering a synthetic designer TAL effector to boost SWEET gene expression. In either case, compatible or incompatible, target gene expression and lesion formation are reduced in the presence of xa5. The results indicate that xa5 functions as a quantitative trait locus, dampening effector function, and, regardless of compatibility, target gene expression. Resistance is hypothesized to occur when S gene expression, and, by inference, sucrose leakage, falls below a threshold level. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  20. XA21-specific induction of stress-related genes following Xanthomonas infection of detached rice leaves

    PubMed Central

    Liu, Furong; Chen, Huamin; Wei, Tong; Nguyen, Yen P.; Shaker, Isaac W.F.

    2016-01-01

    The rice XA21 receptor kinase confers robust resistance to the bacterial pathogen Xanthomonas oryzaepv. oryzae (Xoo). We developed a detached leaf infection assay to quickly and reliably measure activation of the XA21-mediated immune response using genetic markers. We used RNA sequencing of elf18 treated EFR:XA21:GFP plants to identify candidate genes that could serve as markers for XA21 activation. From this analysis, we identified eight genes that are up-regulated in both in elf18 treated EFR:XA21:GFP rice leaves and Xoo infected XA21 rice leaves. These results provide a rapid and reliable method to assess bacterial-rice interactions. PMID:27703843

  1. A ΩXaV motif in the Rift Valley fever virus NSs protein is essential for degrading p62, forming nuclear filaments and virulence

    PubMed Central

    Cyr, Normand; de la Fuente, Cynthia; Lecoq, Lauriane; Guendel, Irene; Chabot, Philippe R.; Kehn-Hall, Kylene; Omichinski, James G.

    2015-01-01

    Rift Valley fever virus (RVFV) is a single-stranded RNA virus capable of inducing fatal hemorrhagic fever in humans. A key component of RVFV virulence is its ability to form nuclear filaments through interactions between the viral nonstructural protein NSs and the host general transcription factor TFIIH. Here, we identify an interaction between a ΩXaV motif in NSs and the p62 subunit of TFIIH. This motif in NSs is similar to ΩXaV motifs found in nucleotide excision repair (NER) factors and transcription factors known to interact with p62. Structural and biophysical studies demonstrate that NSs binds to p62 in a similar manner as these other factors. Functional studies in RVFV-infected cells show that the ΩXaV motif is required for both nuclear filament formation and degradation of p62. Consistent with the fact that the RVFV can be distinguished from other Bunyaviridae-family viruses due to its ability to form nuclear filaments in infected cells, the motif is absent in the NSs proteins of other Bunyaviridae-family viruses. Taken together, our studies demonstrate that p62 binding to NSs through the ΩXaV motif is essential for degrading p62, forming nuclear filaments and enhancing RVFV virulence. In addition, these results show how the RVFV incorporates a simple motif into the NSs protein that enables it to functionally mimic host cell proteins that bind the p62 subunit of TFIIH. PMID:25918396

  2. Comparison of three different anti-Xa assays in major orthopedic surgery patients treated with fondaparinux.

    PubMed

    Ikejiri, Makoto; Wada, Hideo; Yamaguchi, Toshio; Miyazaki, Shinichi; Hasegawa, Masahiro; Wakabayashi, Hiroki; Asanuma, Kunihiro; Sakaguchi, Akane; Matsumoto, Takeshi; Ohishi, Kohshi; Fujimoto, Naoki; Yamada, Norikazu; Ito, Masaaki; Katayama, Naoyuki; Sudo, Akihiro

    2016-05-01

    Anti-Xa assays are useful for monitoring the effects of selective anti-Xa drugs, such as fondaparinux, in the prophylaxis of deep vein thrombosis. In the present study, anti-Xa activity was measured using three different assays, Testzym(®) Heparin S, STA(®)-Liquid Anti-Xa and HemosIL(®) Liquid Heparin. Anti-Xa activity in each assay gradually increased from day one after administration to day eight, and still remained on day 15. Although there were significant differences in anti-Xa activity among the three assays, the activity showed significant correlation across assays. There were no significant differences in the anti-Xa activity between patients with and without DVT or between patients with and without massive bleeding on day one before and after administration, day four, day eight and day 15. Anti-Xa activity in each assay was weakly correlated with antithrombin (AT) activity. The AT activity in patients were significantly higher on days four, eight and 15 compared with day one before and after administration, suggesting that AT activity increases following the administration of fondaparinux. The three anti-Xa assay kits tested are useful for monitoring fondaparinux treatment in orthopedic surgery patients.

  3. Rice Xa21 primed genes and pathways that are critical for combating bacterial blight infection.

    PubMed

    Peng, Hai; Chen, Zheng; Fang, Zhiwei; Zhou, Junfei; Xia, Zhihui; Gao, Lifen; Chen, Lihong; Li, Lili; Li, Tiantian; Zhai, Wenxue; Zhang, Weixiong

    2015-07-17

    Rice bacterial blight (BB) is a devastating rice disease. The Xa21 gene confers a broad and persistent resistance against BB. We introduced Xa21 into Oryza sativa L ssp indica (rice 9311), through multi-generation backcrossing, and generated a nearly isogenic, blight-resistant 9311/Xa21 rice. Using next-generation sequencing, we profiled the transcriptomes of both varieties before and within four days after infection of bacterium Xanthomonas oryzae pv. oryzae. The identified differentially expressed (DE) genes and signaling pathways revealed insights into the functions of Xa21. Surprisingly, before infection 1,889 genes on 135 of the 316 signaling pathways were DE between the 9311/Xa21 and 9311 plants. These Xa21-mediated basal pathways included mainly those related to the basic material and energy metabolisms and many related to phytohormones such as cytokinin, suggesting that Xa21 triggered redistribution of energy, phytohormones and resources among essential cellular activities before invasion. Counter-intuitively, after infection, the DE genes between the two plants were only one third of that before the infection; other than a few stress-related pathways, the affected pathways after infection constituted a small subset of the Xa21-mediated basal pathways. These results suggested that Xa21 primed critically important genes and signaling pathways, enhancing its resistance against bacterial infection.

  4. Factors influencing preferences of Korean people toward advance directives.

    PubMed

    Su Hyun Kim

    2011-07-01

    Although Korean society has begun to seek a way of utilizing advance directives, there is not much known about the factors influencing the average Korean person's preference toward advance directives. The purpose of this study was to examine factors, in addition to demographic variables, influencing preferences regarding advance directives. These include: to what extent people's awareness of advance directives, preferences of extending their life at the end of life, experience of illness and medical care, and family functioning independently influence the preferences toward advance directives. The participants were 382 community-dwelling Korean people. The data analysis was performed using hierarchical multiple logistic regression analysis. The findings showed that a majority of Korean people had a positive preference on advance directives and the factors influencing their preferences for advance directives were the preferences against the use of life-sustaining treatment at the end of life, a good self-rated heath status, and an unsatisfactory family functioning.

  5. Clinical experience of anti-Xa monitoring in critically ill dogs receiving dalteparin.

    PubMed

    Lynch, Alex M; deLaforcade, Armelle M; Sharp, Claire R

    2014-01-01

    To describe a population of critically ill dogs receiving dalteparin monitored with an anti-Xa assay, to assess the potential utility of serial monitoring, and to investigate the association between pre-treatment thromboelastography (TEG) and the ability to achieve targeted anti-Xa activity. Descriptive retrospective study. Veterinary teaching hospital. Thirty-eight client-owned dogs receiving dalteparin and monitored with an anti-Xa assay. None. Medical records were retrospectively reviewed for signalment, underlying disease, clinicopathological data, occurrence of thromboembolic events, complications, and outcome. Thirty-eight dogs receiving dalteparin were monitored with an anti-Xa assay. Diseases included hematological disease, protein-losing disease, neoplastic disease, and septic processes. Pretreatment hypercoagulability was present in 34/35 dogs by assessment of TEG. Five cases of thromboembolism were confirmed prior to starting treatment and 4 cases occurred during hospitalization. Bleeding complications were rare (3/38) and 29/38 dogs survived to discharge. Interpretation of the anti-Xa assay allowed for dose adjustment although reliable achievement of target anti-Xa activity was not demonstrated. Dogs with higher G values on pretreatment TEG were significantly less likely to achieve the target anti-Xa activity (ie, be above or below the target range). Dalteparin was well tolerated in a heterogeneous population of dogs. However, dose adjustment in response to anti-Xa activity interpretation inconsistently resulted in subsequent attainment of the target anti-Xa range. Development of guidelines may be warranted to more consistently achieve the target range. Dogs that appear more hypercoagulable on pre-treatment TEG may require closer monitoring and greater dose adjustment to achieve the target anti-Xa range. © Veterinary Emergency and Critical Care Society 2014.

  6. RNA Splicing Factors and RNA-Directed DNA Methylation.

    PubMed

    Huang, Chao-Feng; Zhu, Jian-Kang

    2014-03-26

    RNA-directed histone and/or DNA modification is a conserved mechanism for the establishment of epigenetic marks from yeasts and plants to mammals. The heterochromation formation in yeast is mediated by RNAi-directed silencing mechanism, while the establishment of DNA methylation in plants is through the RNA-directed DNA methylation (RdDM) pathway. Recently, splicing factors are reported to be involved in both RNAi-directed heterochromatin formation in yeast and the RdDM pathway in plants. In yeast, splicing factors may provide a platform for facilitating the siRNA generation through an interaction with RDRC and thereby affect the heterochromatin formation, whereas in plants, various splicing factors seem to act at different steps in the RdDM pathway.

  7. Measurement and reversal of the direct oral anticoagulants.

    PubMed

    Samuelson, Bethany T; Cuker, Adam

    2017-01-01

    Direct oral anticoagulants (DOACs) offer noninferior efficacy and improved safety compared to vitamin K antagonists (VKAs) for the prevention and treatment of venous thromboembolism and for the prevention of stroke and systemic embolism in nonvalvular atrial fibrillation. Unlike VKAs, DOACs do not require routine laboratory monitoring of anticoagulant effect and dose adjustment. In certain situations, however, laboratory assessment of anticoagulant effect may be desirable. Here we review the utility of currently available assays for assessment of DOAC effect and recommend an optimal assessment strategy for each drug, including calibrated dilute thrombin time or ecarin-based assays for dabigatran and calibrated anti-Xa activity assays for the factor Xa inhibitors. We also discuss reversal strategies, both specific and nonspecific, for each drug, including the preferential use of idarucizumab for the reversal of dabigatran and two agents, andexanet and ciraparantag, currently under development for the reversal of rivaroxaban, apixaban, and edoxaban. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. The role of intrinsic factors in control of arm movement direction: implications from directional preferences.

    PubMed

    Dounskaia, Natalia; Goble, Jacob A; Wang, Wanyue

    2011-03-01

    The role of extrinsic and intrinsic factors in control of arm movement direction remains under debate. We addressed this question by investigating preferences in selection of movement direction and whether factors causing these preferences have extrinsic or intrinsic nature. An unconstrained free-stroke drawing task was used during which participants produced straight strokes on a horizontal table, choosing the direction and the beginning and end of each stroke arbitrarily. The variation of the initial arm postures across strokes provided a possibility to distinguish between the extrinsic and intrinsic origins of directional biases. Although participants were encouraged to produce strokes equally in all directions, each participant demonstrated preferences for some directions over the others. However, the preferred directions were not consistent across participants, suggesting no directional preferences in extrinsic space. Consistent biases toward certain directions were revealed in intrinsic space representing initial arm postures. Factors contributing to the revealed preferences were analyzed within the optimal control framework. The major bias was explained by a tendency predicted by the leading joint hypothesis (LJH) to minimize active interference with interaction torque generated by shoulder motion at the elbow. Some minor biases may represent movements of minimal inertial resistance or maximal kinematic manipulability. These results support a crucial role of intrinsic factors in control of the movement direction of the arm. Based on the LJH interpretation of the major bias, we hypothesize that the dominant tendency was to minimize neural effort for control of arm intersegmental dynamics. Possible organization of neural processes underlying optimal selection of movement direction is discussed.

  9. Inhibitory properties of separate recombinant Kunitz-type-protease-inhibitor domains from tissue-factor-pathway inhibitor.

    PubMed

    Petersen, L C; Bjørn, S E; Olsen, O H; Nordfang, O; Norris, F; Norris, K

    1996-01-15

    Tissue-factor-pathway inhibitor (TFPI) is a multivalent inhibitor with three tandemly arranged Kunitz- type-protease-inhibitor (KPI) domains. Previous studies [Girard, Y. J., Warren, L. A., Novotny , W. F., Likert, K. M., Brown, S. G., Miletich, J. R & Broze, G. J. (1989) Nature 338, 518-520] by means of site-directed mutagenesis indicated that KPI domain 1 interacts with factor VIIa, that KPI domain 2 interacts with factor Xa, and that KPI domain 3 is apparently without inhibitory function. To elucidate the reaction mechanism of this complex inhibitor, we followed a different approach and studied the inhibitory properties of fragments of TFPI obtained by expression in yeast. Results obtained with TFPI-(1-161)-peptide and separate recombinant TFPI-KPI domains 1, 2 and 3 showed that KPI domain 1 inhibited factor VIIa/tissue factor (Ki = 250 nM), KPI domain 2 inhibited factor Xa (Ki = 90 nM), and that KPI domain 3 was without detectable inhibitory function. Studies with separate KPI domains also showed that KPI domain 2 was mainly responsible for inhibition of trypsin (Ki = 0.1 nM) and chymotrypsin (Ki = 0.75 nM), whereas KPI domain 1 inhibited plasmin (Ki = 26 nM) and cathepsin G (Ki = 200 nM). The structural basis for the interaction between serine proteases and KPI domains is discussed in terms of putative three-dimensional models of the proteins derived by comparative molecular-modelling methods. Studies of factor Xa inhibition by intact TFPI (Ki approximately 0.02 nM) suggested that regions other than the contact area of the KPI domain, interacted strongly with factor Xa. Secondary-site interactions were crucial for TFPI inhibition of factor Xa but was of little or no importance for its inhibition of trypsin.

  10. Fast Rotation of a Subkilometer-sized Near-Earth Object 2011 XA3

    NASA Astrophysics Data System (ADS)

    Urakawa, Seitaro; Ohtsuka, Katsuhito; Abe, Shinsuke; Ito, Takashi; Nakamura, Tomoki

    2014-05-01

    We present light curve observations and their multiband photometry for near-Earth object (NEO) 2011 XA3. The light curve has shown a periodicity of 0.0304 ± 0.0003 days (= 43.8 ± 0.4 minutes). The fast rotation shows that 2011 XA3 is in a state of tension (i.e., a monolithic asteroid) and cannot be held together by self-gravitation. Moreover, the multiband photometric analysis indicates that the taxonomic class of 2011 XA3 is S-complex, or V-type. Its estimated effective diameter is 225 ± 97 m (S-complex) and 166 ± 63 m (V-type), respectively. Therefore, 2011 XA3 is a candidate for the second-largest, fast-rotating, monolithic asteroid. Moreover, the orbital parameters of 2011 XA3 are apparently similar to those of NEO (3200) Phaethon, but F/B-type. We computed the orbital evolutions of 2011 XA3 and Phaethon. However, the results of the computation and distinct taxonomy indicate that neither of the asteroids is of common origin.

  11. Fast rotation of a subkilometer-sized near-Earth object 2011 XA{sub 3}

    SciTech Connect

    Urakawa, Seitaro; Ohtsuka, Katsuhito; Abe, Shinsuke; Ito, Takashi; Nakamura, Tomoki

    2014-05-01

    We present light curve observations and their multiband photometry for near-Earth object (NEO) 2011 XA{sub 3}. The light curve has shown a periodicity of 0.0304 ± 0.0003 days (= 43.8 ± 0.4 minutes). The fast rotation shows that 2011 XA{sub 3} is in a state of tension (i.e., a monolithic asteroid) and cannot be held together by self-gravitation. Moreover, the multiband photometric analysis indicates that the taxonomic class of 2011 XA{sub 3} is S-complex, or V-type. Its estimated effective diameter is 225 ± 97 m (S-complex) and 166 ± 63 m (V-type), respectively. Therefore, 2011 XA{sub 3} is a candidate for the second-largest, fast-rotating, monolithic asteroid. Moreover, the orbital parameters of 2011 XA{sub 3} are apparently similar to those of NEO (3200) Phaethon, but F/B-type. We computed the orbital evolutions of 2011 XA{sub 3} and Phaethon. However, the results of the computation and distinct taxonomy indicate that neither of the asteroids is of common origin.

  12. Directional reflectance factor distributions of a cotton row crop

    NASA Technical Reports Server (NTRS)

    Kimes, D. S.; Newcomb, W. W.; Schutt, J. B.; Pinter, P. J., Jr.; Jackson, R. D.

    1984-01-01

    The directional reflectance factor distribution spanning the entire exitance hemisphere was measured for a cotton row crop (Gossypium barbadense L.) with 39 percent ground cover. Spectral directional radiances were taken in NOAA satellite 7 AVHRR bands 1 and 2 using a three-band radiometer with restricted 12 deg full angle field of view at half peak power points. Polar co-ordinate system plots of directional reflectance factor distributions and three-dimensional computer graphic plots of scattered flux were used to study the dynamics of the directional reflectance factor distribution as a function of spectral band, geometric structure of the scene, solar zenith and azimuth angles, and optical properties of the leaves and soil. The factor distribution of the incomplete row crops was highly polymodal relative to that for complete vegetation canopies. Besides the enhanced reflectance for the antisolar point, a reflectance minimum was observed towards the forwardscatter direction in the principle plane of the sun. Knowledge of the mechanics of the observed dynamics of the data may be used to provide rigorous validation for two- or three-dimensional radiative transfer models, and is important in interpreting aircraft and satellite data where the solar angle varies widely.

  13. A comparative approach expands the protein-protein interaction node of the immune receptor XA21 in wheat and rice

    PubMed Central

    Yang, Baoju; Ruan, Randy; Cantu, Dario; Wang, Xiaodong; Ji, Wanquan; Ronald, Pamela C; Dubcovsky, Jorge

    2016-01-01

    The rice (Oryza sativa) OsXA21 receptor kinase is a well-studied immune receptor that initiates a signal transduction pathway leading to resistance to Xanthomonas oryzae pv. oryzae. Two homologs of OsXA21 were identified in wheat (Triticum aestivum): TaXA21-like1 located in a syntenic region with OsXA21, and TaXA21-like2 located in a non-syntenic region. Proteins encoded by these two wheat genes interact with four wheat orthologs of known OsXA21 interactors. In this study, we screened a wheat yeast-two-hybrid (Y2H) library using the cytosolic portion of TaXA21-like1 as bait to identify additional interactors. Using full-length T. aestivum and T. monococcum proteins and Y2H assays we identified three novel TaXA21-like1 interactors (TaARG, TaPR2, TmSKL1) plus one previously known in rice (TaSGT1). An additional full-length wheat protein (TaCIPK14) interacted with TaXA21-like2 and OsXA21 but not with TaXA21-like1. The interactions of TaXA21-like1 with TmSKL1 and TaSGT1 were also observed in rice protoplasts using bimolecular fluorescence complementation (BiFC) assays. We then cloned the rice homologs of the novel wheat interactors and confirmed that they all interact with OsXA21. This last result suggests that inter-specific comparative interactome analyses can be used not only to transfer known interactions from rice to wheat, but also to identify novel interactions in rice. PMID:23957671

  14. AvrXa27 binding influences unwinding of the double-stranded DNA in the UPT box.

    PubMed

    Zhao, Jing; Zhang, Bo; Jiang, Junpeng; Liu, Nanv; Wei, Qi; Xi, Xuguang; Fu, Jing

    2017-03-04

    Transcription-Activator Like (TAL) effectors, delivered by Xanthomonas pathogens bind specifically to UP-regulated by TAL effectors (UPT) box of the host gene promoter to arouse disease or trigger defense response. This type of protein-DNA interaction model has been applied in site-directed genome editing. However, the off-target effects of TAL have severely hindered the development of this promising technology. To better exploit the specific interaction and to deeper understand the TAL-induced host transcription rewiring, the binding between the central repeat region (CRR) of the TAL effector AvrXa27 and its UPT box variants was studied by kinetics analysis and TAL-blocked helicase unwinding assay. The results revealed that while AvrXa27 exhibited the highest affinity to the wild type UPT box, it could also bind to mutated UPT box variants, implying the possibility of non-specific interactions. Furthermore, some of these non-specific combinations restricted the helicase-elicited double-stranded DNA (dsDNA) separation to a greater extent. Our findings provide insight into the mechanism of TAL transcriptional activation and are beneficial to TAL-mediated genome modification.

  15. Factors influencing individual variation in perceptual directional microphone benefit.

    PubMed

    Keidser, Gitte; Dillon, Harvey; Convery, Elizabeth; Mejia, Jorge

    2013-01-01

    Large variations in perceptual directional microphone benefit, which far exceed the variation expected from physical performance measures of directional microphones, have been reported in the literature. The cause for the individual variation has not been systematically investigated. To determine the factors that are responsible for the individual variation in reported perceptual directional benefit. A correlational study. Physical performance measures of the directional microphones obtained after they had been fitted to individuals, cognitive abilities of individuals, and measurement errors were related to perceptual directional benefit scores. Fifty-nine hearing-impaired adults with varied degrees of hearing loss participated in the study. All participants were bilaterally fitted with a Motion behind-the-ear device (500 M, 501 SX, or 501 P) from Siemens according to the National Acoustic Laboratories' non-linear prescription, version two (NAL-NL2). Using the Bamford-Kowal-Bench (BKB) sentences, the perceptual directional benefit was obtained as the difference in speech reception threshold measured in babble noise (SRTn) with the devices in directional (fixed hypercardioid) and in omnidirectional mode. The SRTn measurements were repeated three times with each microphone mode. Physical performance measures of the directional microphone included the angle of the microphone ports to loudspeaker axis, the frequency range dominated by amplified sound, the in situ signal-to-noise ratio (SNR), and the in situ three-dimensional, articulation-index weighted directivity index (3D AI-DI). The cognitive tests included auditory selective attention, speed of processing, and working memory. Intraparticipant variation on the repeated SRTn's and the interparticipant variation on the average SRTn were used to determine the effect of measurement error. A multiple regression analysis was used to determine the effect of other factors. Measurement errors explained 52% of the variation

  16. Unfractionated heparin dose requirements targeting intermediate intensity antifactor Xa concentration during pregnancy.

    PubMed

    Clark, Nathan P; Delate, Thomas; Cleary, Steven J; Witt, Daniel M

    2010-04-01

    To describe unfractionated heparin (UFH) dosing requirements and monitoring parameters to achieve target antifactor Xa concentrations in pregnant women receiving intermediate-dose UFH therapy. Retrospective cohort analysis. Centralized anticoagulation service in an integrated health care delivery system. Twenty-five pregnant women (who had 27 pregnancies) who received intermediate-dose UFH between January 1, 1998, and March 31, 2005. Demographic and clinical data were retrieved by using an integrated electronic medical, pharmacy, and laboratory records system. The primary outcome was the required UFH dose at the time of first target antifactor Xa level achieved. Antifactor Xa levels were measured at the mid-dosing interval for UFH. An antifactor Xa assay concentration of 0.1-0.3 unit/ml was used as the target range for intermediate-dose UFH for antithrombotic management of pregnant women as described in the American College of Chest Physicians clinical practice guidelines. The mean UFH dose required to achieve this target antifactor Xa range was 236.9 units/kg/day. The UFH doses required to achieve target antifactor Xa levels correlated significantly with patient weight (r = 0.682, p<0.001). The final UFH dose/kg required at the end of pregnancy was similar to that at the first target level (p>0.05) when adjusted for weight. However, the total daily amount of UFH did increase by the end of pregnancy (21,889 vs 19,320 units, p=0.02). There was an average of 7.9 antifactor Xa determinations and 3.1 dosage modifications during the mean of 19 weeks of antenatal UFH therapy. Most (62%) antifactor Xa levels were within the target range. No thromboembolic events, heparin-induced thrombocytopenia, or osteopenic fracture occurred. There was one hemorrhagic complication that resolved with temporary withdrawal of UFH. Pregnant women required a mean UFH dose of 236.9 units/kg/day to achieve the targeted antifactor Xa level of 0.1-0.3 unit/ml. The required UFH doses correlated

  17. Direct Extrapolation of Biota-sediment Accumulation Factors (BSAFs)

    EPA Science Inventory

    Biota-sediment accumulation factors (BSAFs) for fish and shellfish were extrapolated directly from one location and species to other species, to other locations within a site, to other sites, and their combinations. The median errors in the extrapolations across species at a loc...

  18. Direct Extrapolation of Biota-sediment Accumulation Factors (BSAFs)

    EPA Science Inventory

    Biota-sediment accumulation factors (BSAFs) for fish and shellfish were extrapolated directly from one location and species to other species, to other locations within a site, to other sites, and their combinations. The median errors in the extrapolations across species at a loc...

  19. Determination of dabigatran, rivaroxaban and apixaban by ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) and coagulation assays for therapy monitoring of novel direct oral anticoagulants.

    PubMed

    Schmitz, E M H; Boonen, K; van den Heuvel, D J A; van Dongen, J L J; Schellings, M W M; Emmen, J M A; van der Graaf, F; Brunsveld, L; van de Kerkhof, D

    2014-10-01

    Three novel direct oral anticoagulants (DOACs) have recently been registered by the Food and Drug Administration and European Medicines Agency Commission: dabigatran, rivaroxaban, and apixaban. To quantify DOACs in plasma, various dedicated coagulation assays have been developed. To develop and validate a reference ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) method and to evaluate the analytical performance of several coagulation assays for quantification of dabigatran, rivaroxaban, and apixaban. The developed UPLC-MS/MS method was validated by determination of precision, accuracy, specificity, matrix effects, lower limits of detection, carry-over, recovery, stability, and robustness. The following coagulation assays were evaluated for accuracy and precision: laboratory-developed (LD) diluted thrombin time (dTT), Hemoclot dTT, Pefakit PiCT, ECA, Liquid anti-Xa, Biophen Heparin (LRT), and Biophen DiXal anti-Xa. Agreement between the various coagulation assays and UPLC-MS/MS was determined with random samples from patients using dabigatran or rivaroxaban. The UPLC-MS/MS method was shown to be accurate, precise, sensitive, stable, and robust. The dabigatran coagulation assay showing the best precision, accuracy and agreement with the UPLC-MS/MS method was the LD dTT test. For rivaroxaban, the anti-factor Xa assays were superior to the PiCT-Xa assay with regard to precision, accuracy, and agreement with the reference method. For apixaban, the Liquid anti-Xa assay was superior to the PiCT-Xa assay. Statistically significant differences were observed between the various coagulation assays as compared with the UPLC-MS/MS reference method. It is currently unknown whether these differences are clinically relevant. When DOACs are quantified with coagulation assays, comparison with a reference method as part of proficiency testing is therefore pivotal. © 2014 International Society on Thrombosis and Haemostasis.

  20. Effect of nadroparin on anti-Xa activity during nocturnal hemodialysis

    PubMed Central

    Buitenwerf, Edward; Risselada, Arne J.; van Roon, Eric N.; Veeger, Nic J.G.M.; Hemmelder, Marc H.

    2015-01-01

    Background Nadroparin is used during hemodialysis to prevent clotting of the extra corporeal system. During nocturnal hemodialysis patients receive an increased dosage of nadroparin compared to conventional hemodialysis. We tested whether the prescribed dosage regimen of nadroparin, according to Dutch guidelines, causes accumulation of nadroparin. Methods Anti-Xa levels were used as an indicator of nadroparin accumulation. Anti-Xa was measured photometrically in 13 patients undergoing nocturnal hemodialysis for 4 nights a week. Nadroparin was administered according to Dutch dosage guidelines. We assessed anti-Xa levels at 4 time points during 1 dialysis week: before the start of the first dialysis session of the week (baseline), prior to (T1) and after the last dialysis session of the week (T2) and before the first dialysis of the following week (T3). Results Patients received 71–95 IU/kg at the start of dialysis and another 50% of the initial dosage after 4 h with a total cumulative dosage of 128 ± 24 IU/kg. Anti-Xa levels increased from 0.017 at baseline to 0.019 at T1 (p = 0.03). Anti-Xa levels were 0.419 ± 0.252 IU/ml at T2 (p < 0.001 vs baseline and T1), whereas anti-Xa levels were not changed at T3 compared to baseline. Conclusion Dosing of nadroparin according to Dutch guidelines in patients on nocturnal hemodialysis does not lead to accumulation of nadroparin. We therefore consider the Dutch dosage guidelines for nadroparin an effective and safe strategy. General significance This article is the first to present data on anti-Xa activity during nocturnal hemodialysis which is a widely used and potentially dangerous therapy. PMID:26672512

  1. Direct inhibition of the NOTCH transcription factor complex.

    PubMed

    Moellering, Raymond E; Cornejo, Melanie; Davis, Tina N; Del Bianco, Cristina; Aster, Jon C; Blacklow, Stephen C; Kung, Andrew L; Gilliland, D Gary; Verdine, Gregory L; Bradner, James E

    2009-11-12

    Direct inhibition of transcription factor complexes remains a central challenge in the discipline of ligand discovery. In general, these proteins lack surface involutions suitable for high-affinity binding by small molecules. Here we report the design of synthetic, cell-permeable, stabilized alpha-helical peptides that target a critical protein-protein interface in the NOTCH transactivation complex. We demonstrate that direct, high-affinity binding of the hydrocarbon-stapled peptide SAHM1 prevents assembly of the active transcriptional complex. Inappropriate NOTCH activation is directly implicated in the pathogenesis of several disease states, including T-cell acute lymphoblastic leukaemia (T-ALL). The treatment of leukaemic cells with SAHM1 results in genome-wide suppression of NOTCH-activated genes. Direct antagonism of the NOTCH transcriptional program causes potent, NOTCH-specific anti-proliferative effects in cultured cells and in a mouse model of NOTCH1-driven T-ALL.

  2. Direct inhibition of the NOTCH transcription factor complex

    PubMed Central

    Moellering, Raymond E.; Cornejo, Melanie; Davis, Tina N.; Del Bianco, Cristina; Aster, Jon C.; Blacklow, Stephen C.; Kung, Andrew L.; Gilliland, D. Gary; Verdine, Gregory L.; Bradner, James E.

    2010-01-01

    Direct inhibition of transcription factor complexes remains a central challenge in the discipline of ligand discovery. In general, these proteins lack surface involutions suitable for high-affinity binding by small molecules. Here we report the design of synthetic, cell-permeable, stabilized α-helical peptides that target a critical protein–protein interface in the NOTCH transactivation complex. We demonstrate that direct, high-affinity binding of the hydrocarbon-stapled peptide SAHM1 prevents assembly of the active transcriptional complex. Inappropriate NOTCH activation is directly implicated in the pathogenesis of several disease states, including T-cell acute lymphoblastic leukaemia (T-ALL). The treatment of leukaemic cells with SAHM1 results in genome-wide suppression of NOTCH-activated genes. Direct antagonism of the NOTCH transcriptional program causes potent, NOTCH-specific anti-proliferative effects in cultured cells and in a mouse model of NOTCH1-driven T-ALL. PMID:19907488

  3. Effect of food, an antacid, and the H2 antagonist ranitidine on the absorption of BAY 59-7939 (rivaroxaban), an oral, direct factor Xa inhibitor, in healthy subjects.

    PubMed

    Kubitza, Dagmar; Becka, Michael; Zuehlsdorf, Michael; Mueck, Wolfgang

    2006-05-01

    To investigate the influence of food and administration of an antacid (aluminum-magnesium hydroxide) or ranitidine on the absorption of BAY 59-7939 (rivaroxaban), 4 randomized studies were performed in healthy male subjects. In 2 food interaction studies, subjects received BAY 59-7939, either as two 5-mg tablets (fasted and fed), four 5-mg tablets (fasted), or one 20-mg tablet (fasted and fed). In 2 drug interaction studies, BAY 59-7939 (six 5-mg tablets) was given alone or with ranitidine (150 mg twice daily, preceded by a 3-day pretreatment phase) or antacid (10 mL). Plasma samples were obtained to assess pharmacokinetic and pharmacodynamic parameters of BAY 59-7939. In the presence of food, time to maximum concentration (t(max)) was delayed by 1.25 hours; maximum concentration (C(max)) and area under the curve (AUC) were increased, with reduced interindividual variability at higher doses of BAY 59-7939. Compared with baseline, BAY 59-7939 resulted in a relative increase in maximum prothrombin time (PT) prolongation of 44% (10 mg) and 53% (20 mg) in the fasted state, compared with 53% and 83% after food. Time to maximum PT prolongation was delayed by 0.5 to 1.5 hours after food, with no relevant influence of food type. No significant difference in C(max) and AUC was observed with coadministration of BAY 59-7939 and ranitidine or antacid.

  4. 3D/3D registration of coronary CTA and biplane XA reconstructions for improved image guidance.

    PubMed

    Dibildox, Gerardo; Baka, Nora; Punt, Mark; Aben, Jean-Paul; Schultz, Carl; Niessen, Wiro; van Walsum, Theo

    2014-09-01

    The authors aim to improve image guidance during percutaneous coronary interventions of chronic total occlusions (CTO) by providing information obtained from computed tomography angiography (CTA) to the cardiac interventionist. To this end, the authors investigate a method to register a 3D CTA model to biplane reconstructions. The authors developed a method for registering preoperative coronary CTA with intraoperative biplane x-ray angiography (XA) images via 3D models of the coronary arteries. The models are extracted from the CTA and biplane XA images, and are temporally aligned based on CTA reconstruction phase and XA ECG signals. Rigid spatial alignment is achieved with a robust probabilistic point set registration approach using Gaussian mixture models (GMMs). This approach is extended by including orientation in the Gaussian mixtures and by weighting bifurcation points. The method is evaluated on retrospectively acquired coronary CTA datasets of 23 CTO patients for which biplane XA images are available. The Gaussian mixture model approach achieved a median registration accuracy of 1.7 mm. The extended GMM approach including orientation was not significantly different (P>0.1) but did improve robustness with regards to the initialization of the 3D models. The authors demonstrated that the GMM approach can effectively be applied to register CTA to biplane XA images for the purpose of improving image guidance in percutaneous coronary interventions.

  5. 3D/3D registration of coronary CTA and biplane XA reconstructions for improved image guidance

    SciTech Connect

    Dibildox, Gerardo Baka, Nora; Walsum, Theo van; Punt, Mark; Aben, Jean-Paul; Schultz, Carl; Niessen, Wiro

    2014-09-15

    Purpose: The authors aim to improve image guidance during percutaneous coronary interventions of chronic total occlusions (CTO) by providing information obtained from computed tomography angiography (CTA) to the cardiac interventionist. To this end, the authors investigate a method to register a 3D CTA model to biplane reconstructions. Methods: The authors developed a method for registering preoperative coronary CTA with intraoperative biplane x-ray angiography (XA) images via 3D models of the coronary arteries. The models are extracted from the CTA and biplane XA images, and are temporally aligned based on CTA reconstruction phase and XA ECG signals. Rigid spatial alignment is achieved with a robust probabilistic point set registration approach using Gaussian mixture models (GMMs). This approach is extended by including orientation in the Gaussian mixtures and by weighting bifurcation points. The method is evaluated on retrospectively acquired coronary CTA datasets of 23 CTO patients for which biplane XA images are available. Results: The Gaussian mixture model approach achieved a median registration accuracy of 1.7 mm. The extended GMM approach including orientation was not significantly different (P > 0.1) but did improve robustness with regards to the initialization of the 3D models. Conclusions: The authors demonstrated that the GMM approach can effectively be applied to register CTA to biplane XA images for the purpose of improving image guidance in percutaneous coronary interventions.

  6. Direct Reprogramming of Fibroblasts into Functional Cardiomyocytes by Defined Factors

    PubMed Central

    Ieda, Masaki; Fu, Ji-Dong; Delgado-Olguin, Paul; Vedantham, Vasanth; Hayashi, Yohei; Bruneau, Benoit G.; Srivastava, Deepak

    2010-01-01

    SUMMARY The reprogramming of fibroblasts to induced pluripotent stem (iPS) cells raises the possibility that a somatic cell could be reprogrammed to an alternative differentiated fate without first becoming a stem/progenitor cell. A large pool of fibroblasts exists in the post-natal heart, yet no single “master regulator” of direct cardiac reprogramming has been identified. Here, we report that a combination of three developmental transcription factors (i.e., Gata4, Mef2c and Tbx5) rapidly and efficiently reprogrammed post-natal cardiac or dermal fibroblasts directly into differentiated cardiomyocyte-like cells. Induced cardiomyocytes expressed cardiac-specific markers, had a global gene expression profile similar to cardiomyocytes, and contracted spontaneously. Fibroblasts transplanted into mouse hearts one day after transduction of the three factors also differentiated into cardiomyocyte-like cells. These findings demonstrate that functional cardiomyocytes can be directly reprogrammed from differentiated somatic cells by defined factors. Reprogramming of endogenous or explanted fibroblasts might provide a source of cardiomyocytes for regenerative approaches. PMID:20691899

  7. TaXA21-A1 on chromosome 5AL is associated with resistance to multiple pests in wheat.

    PubMed

    Liu, Meiyan; Lei, Lei; Powers, Carol; Liu, Zhiyong; Campbell, Kimberly G; Chen, Xianming; Bowden, Robert L; Carver, Brett F; Yan, Liuling

    2016-02-01

    The wheat ortholog of the rice gene OsXA21 against bacterial leaf blight showed resistance to multiple pests in bread wheat but different interacting proteins. A quantitative trait locus QYr.osu-5A on the long arm of chromosome 5A in bread wheat (Triticum aestivum L., 2n = 6x = 42; AABBDD) was previously reported to confer consistent resistance in adult plants to predominant stripe rust races, but the gene causing the quantitative trait locus (QTL) is not known. Single-nucleotide polymorphism (SNP) markers were used to saturate the QTL region. Comparative and syntenic regions between wheat and rice (Oryza sativa) were applied to identify candidate genes for QYr.osu-5A. TaXA21-A1, which is referred to as a wheat ortholog of OsXA21-like gene on chromosome 9 in rice, was mapped under the peak of the QYr.osu-5A. TaXA21-A1 not only explained the phenotypic variation in reaction to different stripe rust races but also showed significant effects on resistance to powdery mildew and Hessian fly biotype BP. The natural allelic variation resulted in the alternations of four amino acids in deduced TaXA21-A1 proteins. The interacting proteins of TaXA21-A1 were different from those identified by OsXA21 on rice chromosome 11 against bacterial leaf blight. TaXA21-A1 confers unique resistance against multiple pests in wheat but might not have common protein interactors or thus overlapping functions with OsXA21 in rice. XA21 function has diverged during evolution of cereal crops. The molecular marker developed for TaXA21-A1 would accelerate its application of the candidate gene at the QYr.osu-5A locus in wheat breeding programs.

  8. Vascular endothelial growth factor receptor 3 directly regulates murine neurogenesis

    PubMed Central

    Calvo, Charles-Félix; Fontaine, Romain H.; Soueid, Jihane; Tammela, Tuomas; Makinen, Taija; Alfaro-Cervello, Clara; Bonnaud, Fabien; Miguez, Andres; Benhaim, Lucile; Xu, Yunling; Barallobre, Maria-José; Moutkine, Imane; Lyytikkä, Johannes; Tatlisumak, Turgut; Pytowski, Bronislaw; Zalc, Bernard; Richardson, William; Kessaris, Nicoletta; Garcia-Verdugo, Jose Manuel; Alitalo, Kari; Eichmann, Anne; Thomas, Jean-Léon

    2011-01-01

    Neural stem cells (NSCs) are slowly dividing astrocytes that are intimately associated with capillary endothelial cells in the subventricular zone (SVZ) of the brain. Functionally, members of the vascular endothelial growth factor (VEGF) family can stimulate neurogenesis as well as angiogenesis, but it has been unclear whether they act directly via VEGF receptors (VEGFRs) expressed by neural cells, or indirectly via the release of growth factors from angiogenic capillaries. Here, we show that VEGFR-3, a receptor required for lymphangiogenesis, is expressed by NSCs and is directly required for neurogenesis. Vegfr3:YFP reporter mice show VEGFR-3 expression in multipotent NSCs, which are capable of self-renewal and are activated by the VEGFR-3 ligand VEGF-C in vitro. Overexpression of VEGF-C stimulates VEGFR-3-expressing NSCs and neurogenesis in the SVZ without affecting angiogenesis. Conversely, conditional deletion of Vegfr3 in neural cells, inducible deletion in subventricular astrocytes, and blocking of VEGFR-3 signaling with antibodies reduce SVZ neurogenesis. Therefore, VEGF-C/VEGFR-3 signaling acts directly on NSCs and regulates adult neurogenesis, opening potential approaches for treatment of neurodegenerative diseases. PMID:21498572

  9. Dynamics of directional reflectance factor distributions for vegetation canopies

    NASA Technical Reports Server (NTRS)

    Kimes, D. S.

    1983-01-01

    Directional reflectance factors that span the entire exitance hemisphere are collected on the ground for a variety of homogeneous vegetation canopies and bare soils. NOAA 6/7 AVHRR bands 1 (0.58-0.68 micron) and 2 (0.73-1.1 microns) are used. When possible, geometric measurements of leaf orientation distributions are taken simultaneously with each spectral measurement. Other supporting structural and optical measurements are made. These data sets are taken at various times of the day for each cover type. These unique sets, together with pertinent data in the literature, are used to investigate the dynamics of the directional reflectance factor distribution as a function of the geometric structure of the scene, solar zenith angle, and optical properties of the scene components (leaves and soil). For complete homogeneous vegetation canopies, the principal trend observed at all sun angles and spectral bands is a minimum reflectance near nadir and increasing reflectance with increasing off-nadir view angle for all azimuth directions.

  10. Interaction of blood coagulation factor Va with phospholipid vesicles examined by using lipophilic photoreagents

    SciTech Connect

    Krieg, U.C.; Isaacs, B.S.; Yemul, S.S.; Esmon, C.T.; Bayley, H.; Johnson, A.E.

    1987-01-13

    Two different lipophilic photoreagents, (/sup 3/H)adamantane diazirine and 3-(trifluoromethyl)-3-(m-(/sup 125/I)iodophenyl)diazirine (TID), have been utilized to examine the interactions of blood coagulation factor Va with calcium, prothrombin, factor Xa, and, in particular, phospholipid vesicles. With each of these structurally dissimilar reagents, the extent of photolabeling of factor Va was greater when the protein was bound to a membrane surface than when it was free in solution. Specifically, the covalent photoreaction with Vl, the smaller subunit of factor Va, was 2-fold higher in the presence of phosphatidylcholine/phosphatidylserine (PC/PS, 3:1) vesicles, to which factor Va binds, than in the presence of 100% PC vesicles, to which the protein does not bind. However, the magnitude of the PC/PS-dependent photolabeling was much less than has been observed previously with integral membrane proteins. It therefore appears that the binding of factor Va to the membrane surface exposes Vl to the lipid core of the bilayer, but that only a small portion of the Vl polypeptide is exposed to, or embedded in, the bilayer core. Addition of either prothrombin or active-site-blocked factor Xa to PC/PS-bound factor Va had little effect on the photolabeling of Vl with TID, but reduced substantially the covalent labeling of Vh, the larger subunit of factor Va. This indicates that prothrombin and factor Xa each cover nonpolar surfaces on Vh when the macromolecules associate on the PC/PS surface. It therefore seems likely that the formation of the prothrombinase complex involves a direct interaction between Vh and factor Xa and between Vh and prothrombin.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Characterization and expression analysis of two cDNAs encoding Xa1 and oxysterol binding proteins in sorghum (Sorghum bicolor)

    USDA-ARS?s Scientific Manuscript database

    Using suppression subtractive hybridization (SSH) and subsequent microarray analysis, expression profiles of sorghum genes responsive to greenbug phloem-feeding were obtained and identified. Among the profiles, two cDNAs designated to MM73 and MM95 were identified to encode Xa1 (Xa1) and oxysterol ...

  12. Rice Xb15, a protein phosphatase 2C, negatively regulates Xa21-mediated resistance and programmed cell death

    USDA-ARS?s Scientific Manuscript database

    The rice pathogen recognition receptor, XA21, confers resistance to specific races of Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight disease. A yeast-two-hybrid screen using the intracellular portion of XA21, including the juxtamembrane (JM) and kinase domain as a bait, i...

  13. Genetic engineering of the Xa10 promoter for broad-spectrum and durable resistance to Xanthomonas oryzae pv. oryzae.

    PubMed

    Zeng, Xuan; Tian, Dongsheng; Gu, Keyu; Zhou, Zhiyun; Yang, Xiaobei; Luo, Yanchang; White, Frank F; Yin, Zhongchao

    2015-09-01

    Many pathovars of plant pathogenic bacteria Xanthomonas species inject transcription activator-like (TAL) effectors into plant host cells to promote disease susceptibility or trigger disease resistance. The rice TAL effector-dependent disease resistance gene Xa10 confers narrow-spectrum race-specific resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight disease in rice. To generate broad-spectrum and durable resistance to Xoo, we developed a modified Xa10 gene, designated as Xa10(E5) . Xa10(E5) has an EBE-amended promoter containing 5 tandemly arranged EBEs each responding specifically to a corresponding virulent or avirulent TAL effector and a stable transgenic rice line containing Xa10(E5) was generated in the cultivar Nipponbare. The Xa10(E5) gene was specifically induced by Xoo strains that harbour the corresponding TAL effectors and conferred TAL effector-dependent resistance to the pathogens at all developmental stages of rice. Further disease evaluation demonstrated that the Xa10(E5) gene in either Nipponbare or 9311 genetic backgrounds provided broad-spectrum disease resistance to 27 of the 28 Xoo strains collected from 11 countries. The development of Xa10(E5) and transgenic rice lines provides new genetic materials for molecular breeding of rice for broad-spectrum and durable disease resistance to bacterial blight.

  14. High-resolution genetic mapping of Xa27(t), a new bacterial blight resistance gene in rice, Oryza sativa L.

    PubMed

    Gu, K; Tian, D; Yang, F; Wu, L; Sreekala, C; Wang, D; Wang, G-L; Yin, Z

    2004-03-01

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae ( Xoo) (Ishyama) Dye, is one of the serious diseases prevalent throughout Asia. In a previous study, a resistance ( R) locus was transferred from the tetraploid wild rice Oryza minuta to the cultivated rice species, Oryza sativa L. Here, we report the fine genetic mapping of the R locus, tentatively designated as Xa27(t). We performed disease evaluation with an Xa27(t) near-isogenic line, IRBB27, testing 35 Xoo strains collected from 11 countries. The Xa27(t) locus conferred a high level of resistance to 27 strains and moderate resistance to three strains. Resistance of the Xa27(t) gene was developmentally regulated in IRBB27 and showed semi-dominant or a dosage effect in the cv. CO39 genetic background. As a prelude to cloning Xa27(t), a molecular mapping strategy was employed with a large mapping population consisting of 3,875 gametes. Three molecular markers, M336, M1081, and M1059, closely linked to Xa27(t), were identified to facilitate the mapping of Xa27(t) to the long arm of chromosome 6. The Xa27(t) locus was confirmed by chromosome landing of M1081 and M1095 markers on the rice genome. Markers derived from the genomic sequence of O. sativa cv. Nipponbare were used to further saturate the Xa27(t) genomic region. Xa27(t) was finally located within a genetic interval of 0.052 cM, flanked by markers M964 and M1197, and co-segregated with markers M631, M1230, and M449.

  15. OsWRKY62 is a negative regulator of basal and Xa21-mediated defense against Xanthomonas oryzae pv. oryzae in rice

    USDA-ARS?s Scientific Manuscript database

    The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo), encodes a receptor-like kinase. Few components involved in transducing the Xa21-mediated defense response have yet been identified. It is reported that XA21 binds to a WRKY transcription fac...

  16. Developing an Anti-Xa-Based Anticoagulation Protocol for Patients with Percutaneous Ventricular Assist Devices.

    PubMed

    Sieg, Adam; Mardis, B Andrew; Mardis, Caitlin R; Huber, Michelle R; New, James P; Meadows, Holly B; Cook, Jennifer L; Toole, J Matthew; Uber, Walter E

    2015-01-01

    Because of the complexities associated with anticoagulation in temporary percutaneous ventricular assist device (pVAD) recipients, a lack of standardization exists in their management. This retrospective analysis evaluates current anticoagulation practices at a single center with the aim of identifying an optimal anticoagulation strategy and protocol. Patients were divided into two cohorts based on pVAD implanted (CentriMag (Thoratec; Pleasanton, CA) / TandemHeart (CardiacAssist; Pittsburgh, PA) or Impella (Abiomed, Danvers, MA)), with each group individually analyzed for bleeding and thrombotic complications. Patients in the CentriMag/TandemHeart cohort were subdivided based on the anticoagulation monitoring strategy (activated partial thromboplastin time (aPTT) or antifactor Xa unfractionated heparin (anti-Xa) values). In the CentriMag/TandemHeart cohort, there were five patients with anticoagulation titrated based on anti-Xa values; one patient developed a device thrombosis and a major bleed, whereas another patient experienced major bleeding. Eight patients received an Impella pVAD. Seven total major bleeds in three patients and no thrombotic events were detected. Based on distinct differences between the devices, anti-Xa values, and outcomes, two protocols were created to guide anticoagulation adjustments. However, anticoagulation in patients who require pVAD support is complex with constantly evolving anticoagulation goals. The ideal level of anticoagulation should be individually determined using several coagulation laboratory parameters in concert with hemodynamic changes in the patient's clinical status, the device, and the device cannulation.

  17. Activated protein C resistance testing for factor V Leiden.

    PubMed

    Kadauke, Stephan; Khor, Bernard; Van Cott, Elizabeth M

    2014-12-01

    Activated protein C resistance assays can detect factor V Leiden with high accuracy, depending on the method used. Factor Xa inhibitors such as rivaroxaban and direct thrombin inhibitors including dabigatran, argatroban, and bivalirudin can cause falsely normal results. Lupus anticoagulants can cause incorrect results in most current assays. Assays that include dilution into factor V-deficient plasma are needed to avoid interference from factor deficiencies or elevations, which can arise from a wide variety of conditions such as warfarin, liver dysfunction, or pregnancy. The pros and cons of the currently available assays are discussed. © 2014 Wiley Periodicals, Inc.

  18. Edoxaban vs warfarin in patients with nonvalvular atrial fibrillation in the US Food and Drug Administration approval population: An analysis from the Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis in Myocardial Infarction 48 (ENGAGE AF-TIMI 48) trial.

    PubMed

    Eisen, Alon; Giugliano, Robert P; Ruff, Christian T; Nordio, Francesco; Gogia, Harinder S; Awasty, Vivek R; Henderson, David A; Mercuri, Michele F; Rutman, Howard; Antman, Elliott M; Braunwald, Eugene

    2016-02-01

    Edoxaban is a specific anti-Xa inhibitor that, in comparison to warfarin, has been found to be noninferior for the prevention of stroke or systemic embolism (SSE) and to reduce bleeding significantly in patients with nonvalvular atrial fibrillation (AF). The US Food and Drug Administration (FDA) approved the higher-dose edoxaban regimen (60/30 mg) in patients with AF and a creatinine clearance of ≤95 mL/min. We report for the first time the clinical characteristics, efficacy, and safety of the FDA-approved population in the ENGAGE AF--TIMI 48 trial. The patients included had been treated with either warfarin or edoxaban 60/30 mg and had a creatinine clearance of ≤95 mL/min. The primary efficacy was SSE, and the principal safety end point was major bleeding (International Society on Thrombosis and Haemostasis classification). Median follow-up was 2.8 years. Patients in the FDA-approved cohort were older, were more likely female, and had higher CHADS2 and HAS-BLED scores, as compared with patients not included in the FDA label. The primary end point occurred in 1.63%/y with edoxaban vs 2.02%/y with warfarin (hazard ratio [HR] 0.81, 95% CI 0.67-0.97, P = .023). Edoxaban significantly reduced the rate of hemorrhagic stroke (HR 0.47, 95% CI 0.31-0.72, P < .001) and cardiovascular death (HR 0.84, 95% CI 0.73-0.97, P = .015). Ischemic stroke rates were similar between the treatment groups (1.31%/y vs 1.39%/y, P = .97). Major bleeding was significantly lower with edoxaban (3.16%/y vs 3.77%/y; HR 0.84, 95% CI 0.72-0.98, P = .023). In the FDA-approved cohort of the ENGAGE AF--TIMI 48 trial, treatment with edoxaban 60/30 mg was superior to warfarin in the prevention of SSE and significantly reduced cardiovascular death and bleeding, especially fatal bleeding and hemorrhagic stroke. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Inhibition of coagulation proteases Xa and IIa decreases ischemia-reperfusion injuries in a preclinical renal transplantation model.

    PubMed

    Tillet, Solenne; Giraud, Sébastien; Kerforne, Thomas; Saint-Yves, Thibaut; Joffrion, Sandrine; Goujon, Jean-Michel; Cau, Jerôme; Mauco, Gérard; Petitou, Maurice; Hauet, Thierry

    2016-12-01

    Coagulation is an important pathway in the pathophysiology of ischemia-reperfusion injuries. In particular, deceased after circulatory death (DCD) donors undergo a no-flow period, a strong activator of coagulation. Hence, therapies influencing the coagulation cascade must be developed. We evaluated the effect of a new highly specific and effective anti-Xa/IIa molecule, with an integrated innovative antidote site (EP217609), in a porcine preclinical model mimicking injuries observed in DCD donor kidney transplantation. Kidneys were clamped for 60 minutes (warm ischemia), then flushed and preserved for 24 hours at 4°C in University of Wisconsin (UW) solution (supplemented or not). EP217609-supplemented UW solution (UW-EP), compared with unfractionated heparin-supplemented UW solution (UW-UFH) or UW alone (UW). A mechanistic investigation was conducted in vitro: addition of EP217609 to endothelial cells during hypoxia at 4°C in the UW solution inhibited thrombin generation during reoxygenation at 37°C in human plasma and reduced tumor necrosis factor alpha, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 messenger RNA cell expressions. In vivo, function recovery was markedly improved in the UW-EP group. Interestingly, levels of thrombin-antithrombin complexes (reflecting thrombin generation) were reduced 60 minutes after reperfusion in the UW-EP group. In addition, 3 months after transplantation, lower fibrosis, epithelial-mesenchymal transition, inflammation, and leukocyte infiltration were observed. Using this new dual anticoagulant, anti-Xa/IIa activity during kidney flush and preservation is protected by reducing thrombin generation at revascularization, improving early function recovery, and decreasing chronic lesions. Such an easy-to-deploy clinical strategy could improve marginal graft outcome.

  20. Laboratory Assessment of the Anticoagulant Activity of Direct Oral Anticoagulants: A Systematic Review.

    PubMed

    Samuelson, Bethany T; Cuker, Adam; Siegal, Deborah M; Crowther, Mark; Garcia, David A

    2017-01-01

    Direct oral anticoagulants (DOACs) are the treatment of choice for most patients with atrial fibrillation and/or noncancer-associated venous thromboembolic disease. Although routine monitoring of these agents is not required, assessment of anticoagulant effect may be desirable in special situations. The objective of this review was to summarize systematically evidence regarding laboratory assessment of the anticoagulant effects of dabigatran, rivaroxaban, apixaban, and edoxaban. PubMed, Embase, and Web of Science were searched for studies reporting relationships between drug levels and coagulation assay results. We identified 109 eligible studies: 35 for dabigatran, 50 for rivaroxaban, 11 for apixaban, and 13 for edoxaban. The performance of standard anticoagulation tests varied across DOACs and reagents; most assays, showed insufficient correlation to provide a reliable assessment of DOAC effects. Dilute thrombin time (TT) assays demonstrated linear correlation (r(2) = 0.67-0.99) across a range of expected concentrations of dabigatran, as did ecarin-based assays. Calibrated anti-Xa assays demonstrated linear correlation (r(2) = 0.78-1.00) across a wide range of concentrations for rivaroxaban, apixaban, and edoxaban. An ideal test, offering both accuracy and precision for measurement of any DOAC is not widely available. We recommend a dilute TT or ecarin-based assay for assessment of the anticoagulant effect of dabigatran and anti-Xa assays with drug-specific calibrators for direct Xa inhibitors. In the absence of these tests, TT or APTT is recommended over PT/INR for assessment of dabigatran, and PT/INR is recommended over APTT for detection of factor Xa inhibitors. Time since last dose, the presence or absence of drug interactions, and renal and hepatic function should impact clinical estimates of anticoagulant effect in a patient for whom laboratory test results are not available. Copyright © 2016 American College of Chest Physicians. Published by Elsevier

  1. The Rice TAL Effector–Dependent Resistance Protein XA10 Triggers Cell Death and Calcium Depletion in the Endoplasmic Reticulum[W

    PubMed Central

    Tian, Dongsheng; Wang, Junxia; Zeng, Xuan; Gu, Keyu; Qiu, Chengxiang; Yang, Xiaobei; Zhou, Zhiyun; Goh, Meiling; Luo, Yanchang; Murata-Hori, Maki; White, Frank F.; Yin, Zhongchao

    2014-01-01

    The recognition between disease resistance (R) genes in plants and their cognate avirulence (Avr) genes in pathogens can produce a hypersensitive response of localized programmed cell death. However, our knowledge of the early signaling events of the R gene–mediated hypersensitive response in plants remains limited. Here, we report the cloning and characterization of Xa10, a transcription activator–like (TAL) effector-dependent R gene for resistance to bacterial blight in rice (Oryza sativa). Xa10 contains a binding element for the TAL effector AvrXa10 (EBEAvrXa10) in its promoter, and AvrXa10 specifically induces Xa10 expression. Expression of Xa10 induces programmed cell death in rice, Nicotiana benthamiana, and mammalian HeLa cells. The Xa10 gene product XA10 localizes as hexamers in the endoplasmic reticulum (ER) and is associated with ER Ca2+ depletion in plant and HeLa cells. XA10 variants that abolish programmed cell death and ER Ca2+ depletion in N. benthamiana and HeLa cells also abolish disease resistance in rice. We propose that XA10 is an inducible, intrinsic terminator protein that triggers programmed cell death by a conserved mechanism involving disruption of the ER and cellular Ca2+ homeostasis. PMID:24488961

  2. 76 FR 80829 - Special Conditions: XtremeAir GmbH, XA42; Acrobatic Category Aerodynamic Stability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ... airplane. The XA42 airplane has a novel or unusual design feature associated with its static stability... acrobatic capability: Neutral longitudinal and lateral static stability characteristics. Discussion The Code of Federal Regulations states static stability criteria for longitudinal, lateral, and...

  3. Fast rotation of a sub-km-sized near-Earth object 2011 XA_3

    NASA Astrophysics Data System (ADS)

    Urakawa, S.; Ohtsuka, K.; Abe, S.; Ito, T.; Nakamura, T.

    2014-07-01

    We present lightcurve observations and multiband photometry for the near-Earth object (NEO) 2011 XA{_3} [1]. Previous studies had shown that most asteroids with rotation periods of < 2.2 h were smaller than 200 m in diameter [2]. The fast-rotating asteroids have structurally significant tensile strength (so-called monolithic asteroids) because such asteroids need to overcome their own centrifugal force. On the other hand, the slow-rotating asteroids larger than 200 m in diameter maintain themselves by their gravity or the cohesive force of bonded aggregates [3], which generally take on a rubble-pile structure [4]. According to a numerical simulation, the fast-rotating asteroids are provided by the collisional disruptions of parent bodies [5]. In-situ observations of the Rosetta spacecraft have revealed that the size frequency distribution of the boulders on (21) Lutetia become shallower in a region of < 150 m in size [6]. When we regard that the size frequency distribution of > 150 m-sized boulders is corresponding to that of the impact ejecta, some ejecta of < 150 m in size may escape from the parent body and likely become small and fast-rotating asteroids. To confirm this hypothesis, we must accumulate more observational data of such asteroids. The purpose of our study is to obtain the rotational period and taxonomic class of the NEO 2011 XA{_3}. The absolute magnitude H = 20.402 ± 0.399 (JPL Small-Body database) of 2011 XA{_3} implies the asteroid to be a subkilometer-sized one. The orbital parameters, a=1.48 au, e=0.93, i=28°, Ω=273°, and ω=323°, are apparently similar to those of the NEO (3200) Phaethon, a=1.27 au, e=0.89, i=22°, Ω=265°, and ω=322°, though indicating a somewhat large difference in the orbital energy. Phaethon is a B/F-type asteroid and probably the main body among the Phaethon-Geminid complex (PGC). The NEOs 2005 UD (F-type) and 1999 YC (C-type) are the other candidates of the PGC along with the Geminid meteor stream [7,8]. We also

  4. The First Test Flight of the Delta Clipper-Experimental Advanced (DC-XA)

    NASA Technical Reports Server (NTRS)

    1966-01-01

    The Delta Clipper-Experimental Advanced (DC-XA) is a single-stage-to-orbit, vertical takeoff / vertical landing launch vehicle concept, whose development was geared to significantly reduce launch cost and provided a test bed for NASA Reusable Launch Vehicle (RLV) technology. This photograph shows the descending vehicle landing during the first successful test flight at White Sands Missile Range, New Mexico. The program was discontinued in 2003.

  5. Acoustic Emission Monitoring of the DC-XA Composite Liquid Hydrogen Tank During Structural Testing

    NASA Technical Reports Server (NTRS)

    Wilkerson, C.

    1996-01-01

    The results of acoustic emission (AE) monitoring of the DC-XA composite liquid hydrogen tank are presented in this report. The tank was subjected to pressurization, tensile, and compressive loads at ambient temperatures and also while full of liquid nitrogen. The tank was also pressurized with liquid hydrogen. AE was used to monitor the tank for signs of structural defects developing during the test.

  6. Materials Testing on the DC-X and DC-XA

    NASA Technical Reports Server (NTRS)

    Smith, Dane; Carroll, Carol; Marschall, Jochen; Pallix, Joan

    1997-01-01

    Flight testing of thermal protection materials has been carried out over a two year period on the base heat shield of the Delta Clipper (DC-X and DC-XA), as well on a body flap. The purpose was to use the vehicle as a test bed for materials and more efficient repair or maintenance processes which would be potentially useful for application on new entry vehicles (i.e., X-33, RLV, planetary probes), as well as on the existing space shuttle orbiters. Panels containing Thermal Protection Systems (TPS) and/or structural materials were constructed either at NASA Ames Research Center or at McDonnell Douglas Aerospace (MDA) and attached between two of the four thrusters in the base heat shield of the DC-X or DC-XA. Three different panels were flown on DC-X flights 6, 7, and 8. A total of 7 panels were flown on DC-XA flights 1, 2, and 3. The panels constructed at Ames contained a variety of ceramic TPS including flexible blankets, tiles with high emissivity coatings, lightweight ceramic ablators and other ceramic composites. The MDS test panels consisted primarily of a variety of metallic composites. This report focuses on the ceramic TPS test results.

  7. Comparative nutritional compositions and proteomics analysis of transgenic Xa21 rice seeds compared to conventional rice.

    PubMed

    Gayen, Dipak; Paul, Soumitra; Sarkar, Sailendra Nath; Datta, Swapan K; Datta, Karabi

    2016-07-15

    Transgenic rice expressing the Xa21 gene have enhanced resistant to most devastating bacterial blight diseases caused by Xanthomonas oryzae pv. oryzae (Xoo). However, identification of unintended modifications, owing to the genetic modification, is an important aspect of transgenic crop safety assessment. In this study, the nutritional compositions of seeds from transgenic rice plants expressing the Xa21 gene were compared against non-transgenic rice seeds. In addition, to detect any changes in protein translation levels as a result of Xa21 gene expression, rice seed proteome analyses were also performed by two-dimensional gel electrophoresis. No significant differences were found in the nutritional compositions (proximate components, amino acids, minerals, vitamins and anti-nutrients) of the transgenic and non-transgenic rice seeds. Although gel electrophoresis identified 11 proteins that were differentially expressed between the transgenic and non-transgenic seed, only one of these (with a 20-fold up-regulation in the transgenic seed) shows nutrient reservoir activity. No new toxins or allergens were detected in the transgenic seeds.

  8. Direct binding of hepatocyte growth factor and vascular endothelial growth factor to CD44v6.

    PubMed

    Volz, Yvonne; Koschut, David; Matzke-Ogi, Alexandra; Dietz, Marina S; Karathanasis, Christos; Richert, Ludovic; Wagner, Moritz G; Mély, Yves; Heilemann, Mike; Niemann, Hartmut H; Orian-Rousseau, Véronique

    2015-06-29

    CD44v6, a member of the CD44 family of transmembrane glycoproteins is a co-receptor for two receptor tyrosine kinases (RTKs), Met and VEGFR-2 (vascular endothelial growth factor receptor 2). CD44v6 is not only required for the activation of these RTKs but also for signalling. In order to understand the role of CD44v6 in Met and VEGFR-2 activation and signalling we tested whether CD44v6 binds to their ligands, HGF (hepatocyte growth factor) and VEGF (vascular endothelial growth factor), respectively. FACS analysis and cellular ELISA showed binding of HGF and VEGF only to cells expressing CD44v6. Direct binding of CD44v6 to HGF and VEGF was demonstrated in pull-down assays and the binding affinities were determined using MicroScale Thermophoresis, fluorescence correlation spectroscopy and fluorescence anisotropy. The binding affinity of CD44v6 to HGF is in the micromolar range in contrast with the high-affinity binding measured in the case of VEGF and CD44v6, which is in the nanomolar range. These data reveal a heparan sulfate-independent direct binding of CD44v6 to the ligands of Met and VEGFR-2 and suggest different roles of CD44v6 for these RTKs.

  9. Item Factor Analysis: Current Approaches and Future Directions

    ERIC Educational Resources Information Center

    Wirth, R. J.; Edwards, Michael C.

    2007-01-01

    The rationale underlying factor analysis applies to continuous and categorical variables alike; however, the models and estimation methods for continuous (i.e., interval or ratio scale) data are not appropriate for item-level data that are categorical in nature. The authors provide a targeted review and synthesis of the item factor analysis (IFA)…

  10. [Pyramiding of senescence-inhibition IPT gene and Xa23 for resistance to bacterial blight in rice (Oryza sativa L.)].

    PubMed

    He, Guang-Ming; Sun, Chuan-Qing; Fu, Yong-Cai; Fu, Qiang; Zhao, Kai-Jun; Wang, Chun-Lian; Zhang, Qi; Ling, Zhong-Zhuan; Wang, Xiang-Kun

    2004-08-01

    Transgenic lines (GC-1) carrying a senescence-inhibition cheimeric gene, IPT (isopentenyl transferase) gene, CBB23, a isogenic lines carrying Xa23 gene for resistance to bacterial blight, and Hexi15, a commercial cultivar showing high resistance to blast disease, were used as donors to pyramid IPT gene and Xa23 by marker-assisted selection (MAS). Seventeen BC1F1 plants pyramiding Xa23 gene and IPT genes were obtained from three multi-cross combinations. Then, the plants carrying Xa23 and IPT genes were crossed with parental lines of two-line hybrid rice, such as 9311, E32, Pei' ai 64S and W9834S. The progenies were backcrossed the acceptor parents. A total of 17 plants carrying Xa23 and IPT genes were detected by PCR, disease resistance identification and analysis of CTK contents of in the four combinations of "(9311///Hexi15/CBB23// GC-1) x 9311", "(E32///Hexi15/CBB23//GC-1) x E32", "(Pei'ai 64S///Hexi15/CBB23//GC-1) x Pei' ai 64S" and "(GC-1/CBB23//W9834S/Hexi15) x W9834S". These plants showed resistance to blast disease by inoculating test using 21 the lines of Pyricularia grisea from Northern China. Six plants of BC2F1 pyramiding Xa23 and IPT genes were further obtained in the combinations of "[(9311///Hexi15/CBB23//GC-1) x 9311] x 9311", "[(E32///Hexi15/CBB23//GC-1) x E32] x E32". After backcrossed and self-crossed 1 approximately 2nd, the plants pyramiding Xa23 and IPT genes can be used in the program of hybrid rice breeding.

  11. Future directions in Alzheimer's disease from risk factors to prevention.

    PubMed

    Imtiaz, Bushra; Tolppanen, Anna-Maija; Kivipelto, Miia; Soininen, Hilkka

    2014-04-15

    The increase in life expectancy has resulted in a high occurrence of dementia and Alzheimer's disease (AD). Research on AD has undergone a paradigm shift from viewing it as a disease of old age to taking a life course perspective. Several vascular, lifestyle, psychological and genetic risk factors influencing this latent period have been recognized and they may act both independently and by potentiating each other. These risk factors have consequently been used to derive risk scores for predicting the likelihood of dementia. Despite population differences, age, low education and vascular risk factors were identified as key factors in all scoring systems. Risk scores can help to identify high-risk individuals who might benefit from different interventions. The European Dementia Prevention Initiative (EDPI), an international collaboration, encourages data sharing between different randomized controlled trials. At the moment, it includes three large ongoing European trials: Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), Prevention of Dementia by Intensive Vascular Care (preDIVA), and Multidomain Alzheimer Prevention study (MAPT). Recently EDPI has developed a "Healthy Aging through Internet Counseling in Elderly" (HATICE) program, which intends to manage modifiable risk factors in an aged population through an easily accessible Internet platform. Thus, the focus of dementia research has shifted from identification of potential risk factors to using this information for developing interventions to prevent or delay the onset of dementia as well as identifying special high-risk populations who could be targeted in intervention trials.

  12. Direct estimates of friction factors for a mobile rippled bed

    NASA Astrophysics Data System (ADS)

    Rodríguez-Abudo, S.; Foster, D. L.

    2017-01-01

    New friction factor estimates are computed from the total momentum transfer applied to a rippled sediment bed. The total time-dependent momentum flux is achieved by implementing the double-averaged horizontal momentum equation on the nearbed flow field collected with PIV. Time-independent friction factors are obtained by regressing the total momentum flux to the common quadratic stress law given by 12ρu∞|u∞|. The resulting friction factors compare favorably with available analysis techniques including energy dissipation, vertical turbulence intensity, and maximum shear stress, but can be 2-6 times smaller than estimates determined with the model by Madsen (1994) and the formula of Swart (1974) using the ripple roughness.

  13. Item Factor Analysis: Current Approaches and Future Directions

    PubMed Central

    Wirth, R. J.; Edwards, Michael C.

    2011-01-01

    The rationale underlying factor analysis applies to continuous and categorical variables alike; however, the models and estimation methods for continuous (i.e., interval or ratio scale) data are not appropriate for item-level data that are categorical in nature. The authors provide a targeted review and synthesis of the item factor analysis (IFA) estimation literature for ordered-categorical data (e.g., Likert-type response scales) with specific attention paid to the problems of estimating models with many items and many factors. Popular IFA models and estimation methods found in the structural equation modeling and item response theory literatures are presented. Following this presentation, recent developments in the estimation of IFA parameters (e.g., Markov chain Monte Carlo) are discussed. The authors conclude with considerations for future research on IFA, simulated examples, and advice for applied researchers. PMID:17402812

  14. The transcriptional factor Osterix directly interacts with RNA helicase A.

    PubMed

    Amorim, Bruna Rabelo; Okamura, Hirohiko; Yoshida, Kaya; Qiu, Lihong; Morimoto, Hiroyuki; Haneji, Tatsuji

    2007-04-06

    Osterix is an osteoblast-specific transcriptional factor, required for bone formation and osteoblast differentiation. Here, we identified new Osterix interacting factors by using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Among the candidates, RNA helicase A was identified to interact with Osterix. To determine the interaction of Osterix with RNA helicase A, immunoprecipitation assay was performed. Western analysis confirmed the association between Osterix and RNA helicase A. Immunocytochemical analysis also showed that Osterix and RNA helicase A were co-localized in HEK 293 cells. Our data suggest that RNA helicase A might be a component of Osterix regulation.

  15. A confirmatory factor analysis of the Self-Directed Learning Readiness Scale.

    PubMed

    Williams, Brett; Brown, Ted

    2013-12-01

    The Self-Directed Learning Readiness Scale measures readiness for self-directed learning among undergraduate healthcare students. While several exploratory factor analyses and one confirmatory factor analysis have examined the psychometric properties of the Self-Directed Learning Readiness Scale, questions have been raised regarding the underlying latent constructs being measured. The objective of this study was to determine the best-fitting Self-Directed Learning Readiness Scale factorial structure among three models published in the literature. Data from the three-factor 40-item Self-Directed Learning Readiness Scale completed by 233 undergraduate paramedic students from four Australian universities (response rate of 26%) were analyzed using maximum likelihood confirmatory factor analysis. Comparison of model fit from the 40-item version was undertaken with the previously documented four-factor 36-item and three-factor 29-item Self-Directed Learning Readiness Scales. The model fit indices of the three one-factor congeneric models with maximum likelihood analysis demonstrate that the 40-item Self-Directed Learning Readiness Scale does not fit the data well. The best fitting model was the four-factor 36-item Self-Directed Learning Readiness Scale followed by the three-factor 29-item models. The confirmatory factor analysis results did not support the overall construct validity of the original 40-item Self-Directed Learning Readiness Scale.

  16. Direct Application of Biota-sediment Accumulation Factors

    EPA Science Inventory

    Biota-sediment bioaccumulation factors (BSAFs) relate chemical residues in fish to chemical concentrations in contaminated sediments. BSAFs used by EPAs Office of Water in developing water quality criteria and by EPAs Superfund program in performing risk assessments for sites wi...

  17. Recent advances in the treatment of venous thromboembolism in the era of the direct oral anticoagulants.

    PubMed

    Weitz, Jeffrey I; Jaffer, Iqbal H; Fredenburgh, James C

    2017-01-01

    The direct oral anticoagulants (DOACs) have now supplanted vitamin K antagonists (VKAs) for the treatment of venous thromboembolism (VTE). The DOACs include dabigatran, which inhibits thrombin, and rivaroxaban, apixaban, and edoxaban, which inhibit factor Xa. The DOACs are as effective for the prevention of recurrence as conventional VTE treatment, consisting of a parenteral anticoagulant followed by a VKA, and are associated with less bleeding. Because of these properties and the convenience of fixed dosing without the need for routine coagulation monitoring, guidelines now recommend DOACs over VKAs for VTE treatment in patients without active cancer. This paper examines the increasing role of the DOACs for VTE treatment.

  18. Gene silencing using the recessive rice bacterial blight resistance gene xa13 as a new paradigm in plant breeding.

    PubMed

    Li, Changyan; Wei, Jing; Lin, Yongjun; Chen, Hao

    2012-05-01

    Resistant germplasm resources are valuable for developing resistant varieties in agricultural production. However, recessive resistance genes are usually overlooked in hybrid breeding. Compared with dominant traits, however, they may confer resistance to different pathogenic races or pest biotypes with different mechanisms of action. The recessive rice bacterial blight resistance gene xa13, also involved in pollen development, has been cloned and its resistance mechanism has been recently characterized. This report describes the conversion of bacterial blight resistance mediated by the recessive xa13 gene into a dominant trait to facilitate its use in a breeding program. This was achieved by knockdown of the corresponding dominant allele Xa13 in transgenic rice using recently developed artificial microRNA technology. Tissue-specific promoters were used to exclude most of the expression of artificial microRNA in the anther to ensure that Xa13 functioned normally during pollen development. A battery of highly bacterial blight resistant transgenic plants with normal seed setting rates were acquired, indicating that highly specific gene silencing had been achieved. Our success with xa13 provides a paradigm that can be adapted to other recessive resistance genes.

  19. The rice immune receptor XA21 recognizes a tyrosine-sulfated protein from a Gram-negative bacterium

    PubMed Central

    Pruitt, Rory N.; Schwessinger, Benjamin; Joe, Anna; Thomas, Nicholas; Liu, Furong; Albert, Markus; Robinson, Michelle R.; Chan, Leanne Jade G.; Luu, Dee Dee; Chen, Huamin; Bahar, Ofir; Daudi, Arsalan; De Vleesschauwer, David; Caddell, Daniel; Zhang, Weiguo; Zhao, Xiuxiang; Li, Xiang; Heazlewood, Joshua L.; Ruan, Deling; Majumder, Dipali; Chern, Mawsheng; Kalbacher, Hubert; Midha, Samriti; Patil, Prabhu B.; Sonti, Ramesh V.; Petzold, Christopher J.; Liu, Chang C.; Brodbelt, Jennifer S.; Felix, Georg; Ronald, Pamela C.

    2015-01-01

    Surveillance of the extracellular environment by immune receptors is of central importance to eukaryotic survival. The rice receptor kinase XA21, which confers robust resistance to most strains of the Gram-negative bacterium Xanthomonas oryzae pv. oryzae (Xoo), is representative of a large class of cell surface immune receptors in plants and animals. We report the identification of a previously undescribed Xoo protein, called RaxX, which is required for activation of XA21-mediated immunity. Xoo strains that lack RaxX, or carry mutations in the single RaxX tyrosine residue (Y41), are able to evade XA21-mediated immunity. Y41 of RaxX is sulfated by the prokaryotic tyrosine sulfotransferase RaxST. Sulfated, but not nonsulfated, RaxX triggers hallmarks of the plant immune response in an XA21-dependent manner. A sulfated, 21–amino acid synthetic RaxX peptide (RaxX21-sY) is sufficient for this activity. Xoo field isolates that overcome XA21-mediated immunity encode an alternate raxX allele, suggesting that coevolutionary interactions between host and pathogen contribute to RaxX diversification. RaxX is highly conserved in many plant pathogenic Xanthomonas species. The new insights gained from the discovery and characterization of the sulfated protein, RaxX, can be applied to the development of resistant crop varieties and therapeutic reagents that have the potential to block microbial infection of both plants and animals. PMID:26601222

  20. The Use of a Dexamethasone-inducible System to Synchronize Xa21 Expression to Study Rice Immunity

    PubMed Central

    Caddell, Daniel F.; Wei, Tong; Park, Chang-Jin; Ronald, Pamela C.

    2016-01-01

    Inducible gene expression systems offer researchers the opportunity to synchronize target gene expression at particular developmental stages and in particular tissues. The glucocorticoid receptor (GR), a vertebrate steroid receptor, has been well adopted for this purpose in plants. To generate steroid-inducible plants, a construct of GAL4-binding domain-VP16 activation domain-GR fusion (GVG) with the target gene under the control of upstream activation sequence (UAS) has been developed and extensively used in plant research. Immune receptors perceive conserved molecular patterns secreted by pathogens and initiate robust immune responses. The rice immune receptor, XA21, recognizes a molecular pattern highly conserved in all sequenced genomes of Xanthomonas, and confers robust resistance to X. oryzae pv. oryzae (Xoo). However, identifying genes downstream of XA21 has been hindered because of the restrained lesion and thus limited defense response region in the plants expressing Xa21. Inducible expression allows for a synchronized immune response across a large amount of rice tissue, well suited for studying XA21-mediated immunity by genome-wide approaches such as transcriptomics and proteomics. In this protocol, we describe the use of this GVG system to synchronize Xa21 expression. PMID:27525297

  1. Explicit polynomial formulas for solutions of the matrix equation AX-XA=C

    SciTech Connect

    Demenchuk, Alexandr K.; Makarov, Evgenii K.

    2009-08-15

    We provide some mathematical tool to analyze the possible theoretical structure of Hamiltonian reconstructed from von Neumann or Heisenberg's equation for a finite-dimensional quantum system. To this end, we give an explicit polynomial representation for the general solution of the matrix equation AX-XA=C together with some (also polynomial) solvability conditions when A and C are some complex square matrices of the same size and the matrix A is semisimple. When the matrix A is normal, we derive a polynomial existence condition for Hermitian solutions and a similar formula for all solutions of this type.

  2. Direct foreign investment: a migration push-factor?

    PubMed

    Sassen-koob, S

    1984-01-01

    Policymakers and analysts now recognize that US military activities abroad contribute to the creation of refugee flows into the US. Previously, immigration into the US was viewed as a result of inept and failed domestic policies in the countries of origin. Results show that recent immigrants to the US come from countries with neither the poorest nor the largest population growth rate in the less developed world. However, the sending countries received US direct foreign investment (DFI) in the 1970s, particularly labor intensive investment in export manufacturing. Significant levels and concentrations of DFI promote emigration through: 1) the incorporation of new segments of the population into wage labor and the associated disruption of traditional work structures, 2) the feminization of the new industrial work force and its impact on the work opportunities of men, and 3) the consolidation of objective and ideological links with the highly industrialized countries where most foreign capital originates. The data suggest an examination of the causes of emigration on a much more specific level than that of underdevelopment, poverty, and population growth. These facts carry immediate policy implications for US immigration organizations: 1) if US firms in export processing zones recruited workers from the pool of unemployed--mostly prime-age males--rather than expanding the labor supply by recruiting young women, thereby disrupting unwaged work structures, and 2) if these firms would desist from having high turnover rates among workers, then the migration impact of this type of development would be minimized.

  3. Anti-Xa-guided enoxaparin thromboprophylaxis reduces rate of deep venous thromboembolism in high-risk trauma patients.

    PubMed

    Singer, George A; Riggi, Gina; Karcutskie, Charles A; Vaghaiwalla, Tanaz M; Lieberman, Howard M; Ginzburg, Enrique; Namias, Nicholas; Lineen, Edward B

    2016-12-01

    Appropriate prophylaxis against venous thromboembolism (VTE) remains undefined. This study evaluated an anti-Xa-guided enoxaparin thromboprophylaxis (TPX) protocol on the incidence of VTE in high-risk trauma patients based on Greenfield's Risk Assessment Profile (RAP) score. This is a retrospective observational study of patients admitted to a trauma intensive care unit over a 12-month period. Patients were included if they received anti-Xa-guided enoxaparin TPX. Dosage was adjusted to a prophylactic peak anti-Xa level of 0.2 to 0.4 IU/mL. Subgroup analysis was performed on high-risk patients (RAP score ≥10) who received lower-extremity duplex ultrasound surveillance for deep vein thrombosis (DVT). Data are expressed as mean ± SD. Significance was assessed at p < 0.05. One hundred thirty-one patients received anti-Xa-guided enoxaparin TPX. Four patients were excluded for age or acute VTE on admission. Fifty-six patients with RAP score of ≥10 and surveillance duplex evaluations were included in the subgroup analysis with mean age 43 ± 20 years, Injury Severity Score of 25 ± 10, and RAP score of 16 ± 4. Prophylactic anti-Xa levels were initially achieved in 34.6% of patients. An additional 25.2% required 40 to 60 mg twice daily to reach prophylactic levels; 39.4% never reached prophylactic levels. Weight, body mass index, ISS, and RAP score were significantly higher with subprophylactic anti-Xa levels. One patient developed bleeding complications (0.8%). No patient developed intracerebral bleeding or heparin-induced thrombocytopenia.Nine VTE events occurred in the high-risk subgroup, including four DVT (7.1%), all asymptomatic, and five pulmonary emboli (8.9%). The historical rate of DVT in similar patients (ISS 31 ± 12 and RAP score 16 ± 5) was 20.5%, a significant decrease (p = 0.031). Mean chest Abbreviated Injury Scale scores were significantly higher for patients developing pulmonary emboli than DVT, 3.0 ± 1.1 vs. 0.0 (p < 0.001). Mean chest

  4. Direct detection of Burkholderia pseudomallei and biological factors in soil.

    PubMed

    Sermswan, Rasana W; Royros, Phairat; Khakhum, Nittaya; Wongratanacheewin, Surasakdi; Tuanyok, Apichai

    2015-07-01

    Burkholderia pseudomallei, a Gram-negative saprophytic bacillus, is a severe infectious agent that causes melioidosis and soil is the most important reservoir. One hundred and forty soil samples were tested for pH, moisture content and total C and N measurements and used for DNA extraction and culture for B. pseudomallei. The quantitative real-time PCR (qPCR) targeting wcbG, a putative capsular polysaccharide biosynthesis protein gene of B. pseudomallei, was developed to detect the bacterium, and random amplified polymorphic DNA (RAPD) was used to detect the microbial diversity in soil. The acidic pH was correlated with the presence of the bacterium. Forty-four soil sites (44/140, 31.4%) were positive for B. pseudomallei by qPCR, of which 21 were positive by culture. The limit of detection is 32 fg of DNA (about 4 genomes). The RAPD method could classify the soil samples into low diversity (LD) and high diversity (HD) sites. The trend of LD was found with B. pseudomallei positive soil sites. The acidity of the soil or metabolites from organisms in the sites may contribute to the presence of the bacterium. Further investigation of microbes by a more robust method should elucidate biological factors that promote the presence of B. pseudomallei and may be used for controlling the bacterium in the environment. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. [New anticoagulants - direct thrombin inhibitors].

    PubMed

    Brand, B; Graf, L

    2012-11-01

    Direct thrombin-inhibitors inactivate not only free but also fibrin-bound thrombin. The group of parenteral direct thrombin-inhibitors includes the recombinant hirudins lepirudin and desirudin, the synthetic hirudin bivalirudin, and the small molecule argatroban. All these compounds do not interact with PF4/heparin-antibodies. Therefore, argatroban as well as bivalirudin are currently used to treat heparin-induced thrombocytopenia (HIT). The oral direct thrombin-inhibitor dabigatran etexilate is already licensed in many countries for the treatment of non-valvular atrial fibrillation. Dabigatran etexilate reveals a stable and predictable effect that allows a medication without dose adjustment or monitoring. The substance shows only few interactions with other drugs but strong inhibitors of p-glycoprotein can increase plasma levels of dabigatran substantially. After oral intake, the prodrug dabigatran etexilate is cleaved by esterase-mediated hydrolyses to the active compound dabigatran. Elimination of dabigatran is predominantly renal. Safety and efficacy of dabigatran etexilate were tested in an extensive clinical study program. Non-inferiority compared to current standard treatments was shown for prophylaxis of venous thromboembolic events after total knee and hip replacement, for stroke prevention in atrial fibrillation, and for treatment of acute venous thromboembolism. In daily practice, Dabigatran etexilate competes against the new direct factor Xa-inhibitors. In the absence of direct comparative clinical trials, it is not yet clear if one class of substances has distinct advantages over the other.

  6. XaNSoNS: GPU-accelerated simulator of diffraction patterns of nanoparticles

    NASA Astrophysics Data System (ADS)

    Neverov, V. S.

    XaNSoNS is an open source software with GPU support, which simulates X-ray and neutron 1D (or 2D) diffraction patterns and pair-distribution functions (PDF) for amorphous or crystalline nanoparticles (up to ∼107 atoms) of heterogeneous structural content. Among the multiple parameters of the structure the user may specify atomic displacements, site occupancies, molecular displacements and molecular rotations. The software uses general equations nonspecific to crystalline structures to calculate the scattering intensity. It supports four major standards of parallel computing: MPI, OpenMP, Nvidia CUDA and OpenCL, enabling it to run on various architectures, from CPU-based HPCs to consumer-level GPUs.

  7. Establishing the heparin therapeutic range using aPTT and anti-Xa measurements for monitoring unfractionated heparin therapy

    PubMed Central

    Byun, Jung-Hyun; Jang, In-Seok; Kim, Jong Woo

    2016-01-01

    Background Unfractionated heparin (UFH) has unstable pharmacokinetics and requires close monitoring. The activated partial thromboplastin time (aPTT) test has been used to monitor UFH therapy for decades in Korea, but its results can be affected by numerous variables. We established an aPTT heparin therapeutic range (HTR) corresponding to therapeutic anti-Xa levels for continuous intravenous UFH administration, and used appropriate monitoring to determine if an adequate dose of UFH was applied. Methods A total of 134 ex vivo samples were obtained from 71 patients with a variety of thromboembolisms. All patients received intravenous UFH therapy and were enrolled from June to September 2015 at Gyeongsang National University Hospital. All laboratory protocols were in accordance with the Clinical and Laboratory Standards Institute guidelines and the College of American Pathologist requirements for aPTT HTR. Results An aPTT range of 87.1 sec to 128.7 sec corresponded to anti-Xa levels of 0.3 IU/mL to 0.7 IU/mL for HTR under our laboratory conditions. Based on their anti-Xa levels, blood specimen distribution were as follows: less than 0.3 IU/mL, 65.7%; 0.3–0.7 IU/mL (therapeutic range), 33.6%; and more than 0.7 IU/mL, 0.7%. No evidence of recurring thromboembolism was observed. Conclusion Using the conventional aPTT target range may lead to inappropriate dosing of UFH. Transitioning from the aPTT test to the anti-Xa assay is required to avoid the laborious validation of the aPTT HTR test, even though the anti-Xa assay is more expensive. PMID:27722127

  8. Independent anti-angiogenic capacities of coagulation factors X and Xa.

    PubMed

    Lange, Soledad; Gonzalez, Ibeth; Pinto, Mauricio P; Arce, Maximiliano; Valenzuela, Rodrigo; Aranda, Evelyn; Elliot, Matias; Alvarez, Marjorie; Henriquez, Soledad; Velasquez, Ethel V; Orge, Felipe; Oliva, Barbara; Gonzalez, Pamela; Villalon, Manuel; Cautivo, Kelly M; Kalergis, Alexis M; Pereira, Karla; Mendoza, Camila; Saez, Claudia; Kato, Sumie; Cuello, Mauricio A; Parborell, Fernanda; Irusta, Griselda; Palma, Veronica; Allende, Miguel L; Owen, Gareth I

    2014-11-01

    Knockout models have shown that the coagulation system has a role in vascular development and angiogenesis. Herein, we report for the first time that zymogen FX and its active form (FXa) possess anti-angiogenic properties. Both the recombinant FX and FXa inhibit angiogenesis in vitro using endothelial EA.hy926 and human umbilical cord vascular endothelial cells (HUVEC). This effect is dependent on the Gla domain of FX. We demonstrate that FX and FXa use different mechanisms: the use of Rivaroxaban (RX) a specific inhibitor of FXa attenuated its anti-angiogenic properties but did not modify the anti-angiogenic effect of FX. Furthermore, only the anti-angiogenic activity of FXa is PAR-1dependent. Using in vivo models, we show that FX and FXa are anti-angiogenic in the zebrafish intersegmental vasculature (ISV) formation and in the chick embryo chorioallantoic membrane (CAM) assays. Our results provide further evidence for the non-hemostatic functions of FX and FXa and demonstrate for the first time a biological role for the zymogen FX.

  9. Novel thrombin and factor Xa inhibitors: challenges to reversal of their anticoagulation effects.

    PubMed

    Yates, Sean; Sarode, Ravi

    2013-11-01

    Warfarin has been the sole oral anticoagulant used in the management of thromboembolic disorders for over 60 years. Target-specific oral anticoagulants (TSOAs) have recently emerged as alternatives to warfarin, because they do not require laboratory monitoring. Nevertheless, with the rising use of TSOAs, there is growing concern among clinicians regarding management of bleeding in patients taking them. Unlike warfarin, there is no antidote or reversal agent for TSOAs. This review summarizes recent developments and attempts to provide a systematic approach to patients on TSOAs presenting with bleeding complications. Currently, data involving clinical management of TSOAs are limited and primarily based on ex-vivo or animal models using hemostatic agents with uncertain implications in bleeding patients. There is a pressing need for randomized clinical trials evaluating the safety and efficacy of hemostatic agents. Without evidence-based guidelines for TSOA management, appropriate patient care requires an understanding of TSOA pharmacology, their effect on coagulation tests and, hence, a correct interpretation of test results, as well as a systematic approach to bleeding complications.

  10. XA27 Depends on an Amino-Terminal Signal-Anchor-Like Sequence to Localize to the Apoplast for Resistance to Xanthomonas oryzae pv oryzae1[W

    PubMed Central

    Wu, Lifang; Goh, Mei Ling; Sreekala, Chellamma; Yin, Zhongchao

    2008-01-01

    The rice (Oryza sativa) gene Xa27 confers resistance to Xanthomonas oryzae pv oryzae, the causal agent of bacterial blight disease in rice. Sequence analysis of the deduced XA27 protein provides little or no clue to its mode of action, except that a signal-anchor-like sequence is predicted at the amino (N)-terminal region of XA27. As part of an effort to characterize the biochemical function of XA27, we decided to determine its subcellular localization. Initial studies showed that a functional XA27-green fluorescent protein fusion protein accumulated in vascular elements, the host sites where the bacterial blight pathogens multiply. The localization of XA27-green fluorescent protein to the apoplast was verified by detection of the protein on cell walls of leaf sheath and root cells after plasmolysis. Similarly, XA27-FLAG localizes to xylem vessels and cell walls of xylem parenchyma cells, revealed by immunogold electron microscopy. XA27-FLAG could be secreted from electron-dense vesicles in cytoplasm to the apoplast via exocytosis. The signal-anchor-like sequence has an N-terminal positively charged region including a triple arginine motif followed by a hydrophobic region. Deletion of the hydrophobic region or substitution of the triple arginine motif with glycine or lysine residues abolished the localization of the mutated proteins to the cell wall and impaired the plant's resistance to X. oryzae pv oryzae. These results indicate that XA27 depends on the N-terminal signal-anchor-like sequence to localize to the apoplast and that this localization is important for resistance to X. oryzae pv oryzae. PMID:18784285

  11. Diurnal changes in reflectance factor due to Sun-row direction interactions

    NASA Technical Reports Server (NTRS)

    Bauer, M. E. (Principal Investigator); Vanderbilt, V. C.; Kollenkark, J. C.; Biehl, L. L.; Robinson, B. F.; Ranson, K. J.

    1981-01-01

    Over a two year period, data were collected regarding the canopies of soybeans grown in rows in planter boxes placed on a turntable in an effort to investigate changes in the spectral reflectance factor related to row direction, Sun direction, soil background, and crop development stage. Results demonstrate that the direction of rows in a soybean canopy can affect the reflectance factor of the canopy by as much as 230%. The results for the red spectral region tend to support the validity of canopy reflectance models; results for the infrared region do not.

  12. Synthesis, purification, and characterization of an Arg sub 152 yields Glu site-directed mutant of recombinant human blood clotting factor VII

    SciTech Connect

    Wildgoose, P.; Kisiel, W. ); Berkner, K.L. )

    1990-04-03

    Coagulation factor VII circulates in blood as a single-chain zymogen of a serine protease and is converted to its activated two-chain form, factor VIIa, by cleavage of an internal peptide bond located at Arg{sub 152}-Ile{sub 153}. Previous studies using serine protease active-site inhibitors suggest that zymogen factor VII may possess sufficient proteolytic activity to initiate the extrinsic pathway of blood coagulation. In order to assess the putative intrinsic proteolytic activity of single-chain factor VII, the authors have constructed a site-specific mutant of recombinant human factor VII in which arginine-152 has been replaced with a glutamic acid residue. Mutant factor VII was purified in a single step from culture supernatants of baby hamster kidney cells transfected with a plasmid containing the sequence for Arg{sub 152} {yields} Glu factor VII using a calcium-dependent, murine anti-factor VII monoclonal antibody column. The clotting activity of mutant factor VII was completely inhibited following incubation with dansyl-Glu-Gly-Arg chloromethyl ketone, suggesting that the apparent clotting activity of mutant factor VII was due to a contaminating serine protease. Immunoblots of mutant factor VII with human factor IXa revealed no cleavage, whereas incubation of mutant factor VII with human factor Xa resulted in cleavage of mutant factor VII and the formation of a lower molecular weight degradation product migrating at M{sup r}{approx}40 000. The results are consistent with the proposal that zymogen factor VII possesses no intrinsic proteolytic activity toward factor X or factor IX.

  13. Analysis of Korean Students' International Mobility by 2-D Model: Driving Force Factor and Directional Factor

    ERIC Educational Resources Information Center

    Park, Elisa L.

    2009-01-01

    The purpose of this study is to understand the dynamics of Korean students' international mobility to study abroad by using the 2-D Model. The first D, "the driving force factor," explains how and what components of the dissatisfaction with domestic higher education perceived by Korean students drives students' outward mobility to seek…

  14. Discovery of non-directional and directional pioneer transcription factors by modeling DNase profile magnitude and shape

    PubMed Central

    Lewis, Sophia; Barkal, Amira A; van Hoff, John Peter; Karun, Vivek; Jaakkola, Tommi; Gifford, David K

    2014-01-01

    Here we describe Protein Interaction Quantitation (PIQ), a computational method that models the magnitude and shape of genome-wide DNase profiles to facilitate the identification of transcription factor (TF) binding sites. Through the use of machine learning techniques, PIQ identified binding sites for >700 TFs from one DNase-seq experiment with accuracy comparable to ChIP-seq for motif-associated TFs (median AUC=0.93 across 303 TFs). We applied PIQ to analyze DNase-seq data from mouse embryonic stem cells differentiating into pre-pancreatic and intestinal endoderm. We identified (n=120) and experimentally validated eight ‘pioneer’ TF families that dynamically open chromatin, enabling other TFs to bind to adjacent DNA. Four pioneer TF families only open chromatin in one direction from their motifs. Furthermore, we identified a class of ‘settler’ TFs whose genomic binding is principally governed by proximity to open chromatin. Our results support a model of hierarchical TF binding in which directional and non-directional pioneer activity shapes the chromatin landscape for population by settler TFs. PMID:24441470

  15. Spatially Directed Guidance of Stem Cell Population Migration by Immobilized Patterns of Growth Factors

    PubMed Central

    Miller, Eric D.; Li, Kang; Kanade, Takeo; Weiss, Lee E.; Walker, Lynn M.; Campbell, Phil G.

    2011-01-01

    We investigated how engineered gradients of exogenous growth factors, immobilized to an extracellular matrix material, influence collective guidance of stem cell populations over extended time (>1 day) and length (>1 mm) scales in vitro. Patterns of low-to-high, high-to-low, and uniform concentrations of heparin-binding epidermal growth factor-like growth factor were inkjet printed at precise locations on fibrin substrates. Proliferation and migration responses of mesenchymal stem cells seeded at pattern origins were observed with time-lapse video microscopy and analyzed using both manual and automated computer vision-based cell tracking techniques. Based on results of established chemotaxis studies, we expected that the low-to-high gradient would most effectively direct cell guidance away from the cell source. All printed patterns, however, were found to direct net collective cell guidance with comparable responses. Our analysis revealed that collective “cell diffusion” down a cell-to-cell confinement gradient originating at the cell starting lines and not the net sum of directed individual cell migration up a growth factor concentration gradient is the principal driving force for directing mesenchymal stem cell population outgrowth from a cell source. These results suggest that simple uniform distributions of growth factors immobilized to an extracellular matrix material may be as effective in directing cell migration into a wound site as more complex patterns with concentration gradients. PMID:21272933

  16. Non-direct patient care factors influencing nursing workload: a review of the literature.

    PubMed

    Myny, Dries; Van Goubergen, Dirk; Gobert, Micheline; Vanderwee, Katrien; Van Hecke, Ann; Defloor, Tom

    2011-10-01

    The aim of this paper was to detect which non-direct patient care factors are related to nursing workload in acute hospital nursing care and to develop a conceptual model to describe the relationship between the non-direct patient care factors and nursing workload. Since the 1930s, efforts to measure nursing workload have been undertaken. Still, it remains unclear which of the non-direct patient care elements are essential to the nursing workload. PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature, Engineering Village 2, Elin and the British Nursing Index were searched from 1970 up to July 2009. Studies were included in this integrative review if they described factors that are related to nursing workload or if they presented models that explored the association between potential factors, excluding the factors related to direct patient care. Thirty publications were included. The influencing variables were classified in five categories based on their level of impact: the hospital and ward, nursing team, individual nurse, patient and family and meta-characteristics. The variables were also classified, based on their cause-effect relationship. Some factors have a direct impact on the patient-nurse relationship, while others have an effect on the work fluency or on the subjective perception of the nursing workload. A conceptual model was built, based on the interaction between both classifications and derived from the systems theory. Nursing workload has a multi-causal aetiology. The influencing factors from this review can be integrated in a workload measurement tool. © 2011 The Authors. Journal of Advanced Nursing © 2011 Blackwell Publishing Ltd.

  17. The Measure of Human Error: Direct and Indirect Performance Shaping Factors

    SciTech Connect

    Ronald L. Boring; Candice D. Griffith; Jeffrey C. Joe

    2007-08-01

    The goal of performance shaping factors (PSFs) is to provide measures to account for human performance. PSFs fall into two categories—direct and indirect measures of human performance. While some PSFs such as “time to complete a task” are directly measurable, other PSFs, such as “fitness for duty,” can only be measured indirectly through other measures and PSFs, such as through fatigue measures. This paper explores the role of direct and indirect measures in human reliability analysis (HRA) and the implications that measurement theory has on analyses and applications using PSFs. The paper concludes with suggestions for maximizing the reliability and validity of PSFs.

  18. Risk of gastrointestinal bleeding with direct oral anticoagulants: a systematic review and network meta-analysis.

    PubMed

    Burr, Nick; Lummis, Katie; Sood, Ruchit; Kane, John Samuel; Corp, Aaron; Subramanian, Venkataraman

    2017-02-01

    Direct oral anticoagulants are increasingly used for a wide range of indications. However, data are conflicting about the risk of major gastrointestinal bleeding with these drugs. We compared the risk of gastrointestinal bleeding with direct oral anticoagulants, warfarin, and low-molecular-weight heparin. For this systematic review and meta-analysis, we searched MEDLINE and Embase from database inception to April 1, 2016, for prospective and retrospective studies that reported the risk of gastrointestinal bleeding with use of a direct oral anticoagulant compared with warfarin or low-molecular-weight heparin for all indications. We also searched the Cochrane Library for systematic reviews and assessment evaluations, the National Health Service (UK) Economic Evaluation Database, and ISI Web of Science for conference abstracts and proceedings (up to April 1, 2016). The primary outcome was the incidence of major gastrointestinal bleeding, with all gastrointestinal bleeding as a secondary outcome. We did a Bayesian network meta-analysis to produce incidence rate ratios (IRRs) with 95% credible intervals (CrIs). We identified 38 eligible articles, of which 31 were included in the primary analysis, including 287 692 patients exposed to 230 090 years of anticoagulant drugs. The risk of major gastrointestinal bleeding with direct oral anticoagulants did not differ from that with warfarin or low-molecular-weight heparin (factor Xa vs warfarin IRR 0·78 [95% CrI 0·47-1·08]; warfarin vs dabigatran 0·88 [0·59-1·36]; factor Xa vs low-molecular-weight heparin 1·02 [0·42-2·70]; and low-molecular-weight heparin vs dabigatran 0·67 [0·20-1·82]). In the secondary analysis, factor Xa inhibitors were associated with a reduced risk of all severities of gastrointestinal bleeding compared with warfarin (0·25 [0.07-0.76]) or dabigatran (0.24 [0.07-0.77]). Our findings show no increase in risk of major gastrointestinal bleeding with direct oral anticoagulants compared with

  19. Clinical pearls: Laboratory assessments of direct oral anticoagulants (DOACS).

    PubMed

    Gosselin, Robert C; Gosselin, Robert; Douxfils, Jonathan; Adcock, Dorothy

    2017-07-05

    Direct oral anticoagulants (DOACS) are being used for stroke prevention in patients with atrial fibrillation as well as for prophylaxis and treatment of venous thromboembolism. Clinicians who treat, or may encounter, patients with DOAC exposure, should be aware of the limitations of coagulation testing in this setting, and seek counsel from their laboratory to understand the effects of DOACS on coagulation results. Generally, assays that employ clot based principles, or methods that require thrombin or Factor Xa activation or substrates may be affected by the presence of DOACS. The clinical laboratory should have an algorithmic testing plan for adequately assessing the presence of all DOACS and readily provide this information to clinicians. We describe Clinical Pearls for DOAC assessment using common and esoteric coagulation testing.

  20. How useful is the monitoring of (low molecular weight) heparin therapy by anti-Xa assay? A laboratory perspective.

    PubMed

    Favaloro, Emmanuel J; Bonar, Roslyn; Aboud, Margaret; Low, Joyce; Sioufi, John; Wheeler, Michael; Lloyd, John; Street, Alison; Marsden, Katherine

    2005-01-01

    We have conducted a series of laboratory-based surveys to assess variability in assay results utilized to monitor heparin anticoagulant therapy. These surveys involved laboratories participating in the Haematology component of the Royal College of Pathologists of Australasia Quality Assurance Program (RCPA QAP). Thirty five of 646 laboratories that were sent a preliminary questionnaire indicated that they performed anti-Xa assays and these laboratories were sent a panel of four plasma samples. These plasma samples contained respectively: (i) no added heparin, (ii) low molecular weight heparin (LMWH), enoxaparin, added to a level of approximately .5 U/mL, (iii) unfractionated heparin added to a level of approximately .5 U/mL, and (iv) LMWH added to a level of approximately 1.0 U/mL. Tests to be performed were the activated partial thromboplastin time (APTT), the thrombin time (TT), fibrinogen, and anti-Xa. As expected, returned results for APTT and TT showed some elevation in heparinized samples while fibrinogen assays were not affected. Anti-Xa assays yielded the following results (median [range]): (i) .01 [0-.11], (ii) .43 [.33-.80], (iii) .23 [.10-.49], and (iv) .90 [.60-1.30]. Thus, although median values were close to those anticipated, there was a wide variation in returned results. In a repeat exercise a few months later laboratories were also asked about their therapeutic ranges (TRs) and provided with an additional vial of LMWH-spiked (1.0 U/mL) plasma labeled as 'heparin-standard' to be used as an assay calibrant. TRs varied substantially between laboratories, from low ranges of .2-.4 to high ranges of .8-1.2. Anti-Xa assay results were similar to those of the first survey: (median [range]): (a) repeat testing: (i) .02 [0-.28], (ii) .47 [.34-.80], (iii) .25 [.14-.58], (iv) .95 [.65-1.31]; (b) repeat testing using survey provided 'heparin-standard': (i) .02 [0-.24], (ii) .55 [.4-.83], (iii) .28 [.10-.63], (iv) 1.00 [.9-1.16]. Thus using the provided

  1. A complex task? Direct modulation of transcription factors with small molecules

    PubMed Central

    Koehler, Angela N.

    2010-01-01

    Transcription factors with aberrant activity in disease are promising yet untested targets for therapeutic development, particularly in oncology. Directly inhibiting or activating the function of a transcription factor requires specific disruption or recruitment of protein-protein or protein-DNA interactions. The discovery or design of small molecules that specifically modulate these interactions has thus far proven to be a significant challenge and the protein class is often perceived to be ‘undruggable.’ This review will summarize recent progress in the development of small-molecule probes of transcription factors and provide evidence to challenge the notion that this important protein class is chemically intractable. PMID:20395165

  2. Lifestyle factors, direct and indirect costs for a Brazilian airline company.

    PubMed

    Rabacow, Fabiana Maluf; Luiz, Olinda do Carmo; Malik, Ana Maria; Burdorf, Alex

    2014-12-01

    OBJECTIVE To analyze lifestyle risk factors related to direct healthcare costs and the indirect costs due to sick leave among workers of an airline company in Brazil. METHODS In this longitudinal 12-month study of 2,201 employees of a Brazilian airline company, the costs of sick leave and healthcare were the primary outcomes of interest. Information on the independent variables, such as gender, age, educational level, type of work, stress, and lifestyle-related factors (body mass index, physical activity, and smoking), was collected using a questionnaire on enrolment in the study. Data on sick leave days were available from the company register, and data on healthcare costs were obtained from insurance records. Multivariate linear regression analysis was used to investigate the association between direct and indirect healthcare costs with sociodemographic, work, and lifestyle-related factors. RESULTS Over the 12-month study period, the average direct healthcare expenditure per worker was US$505.00 and the average indirect cost because of sick leave was US$249.00 per worker. Direct costs were more than twice the indirect costs and both were higher in women. Body mass index was a determinant of direct costs and smoking was a determinant of indirect costs. CONCLUSIONS Obesity and smoking among workers in a Brazilian airline company were associated with increased health costs. Therefore, promoting a healthy diet, physical activity, and anti-tobacco campaigns are important targets for health promotion in this study population.

  3. Lifestyle factors, direct and indirect costs for a Brazilian airline company

    PubMed Central

    Rabacow, Fabiana Maluf; Luiz, Olinda do Carmo; Malik, Ana Maria; Burdorf, Alex

    2014-01-01

    OBJECTIVE To analyze lifestyle risk factors related to direct healthcare costs and the indirect costs due to sick leave among workers of an airline company in Brazil. METHODS In this longitudinal 12-month study of 2,201 employees of a Brazilian airline company, the costs of sick leave and healthcare were the primary outcomes of interest. Information on the independent variables, such as gender, age, educational level, type of work, stress, and lifestyle-related factors (body mass index, physical activity, and smoking), was collected using a questionnaire on enrolment in the study. Data on sick leave days were available from the company register, and data on healthcare costs were obtained from insurance records. Multivariate linear regression analysis was used to investigate the association between direct and indirect healthcare costs with sociodemographic, work, and lifestyle-related factors. RESULTS Over the 12-month study period, the average direct healthcare expenditure per worker was US$505.00 and the average indirect cost because of sick leave was US$249.00 per worker. Direct costs were more than twice the indirect costs and both were higher in women. Body mass index was a determinant of direct costs and smoking was a determinant of indirect costs. CONCLUSIONS Obesity and smoking among workers in a Brazilian airline company were associated with increased health costs. Therefore, promoting a healthy diet, physical activity, and anti-tobacco campaigns are important targets for health promotion in this study population. PMID:26039398

  4. The Relationship between Teachers' Personality Factors and Their Compliance with Administrative Directives.

    ERIC Educational Resources Information Center

    Henderson, Janet C.

    The relationship between teachers' personality factors and their willingness to comply with administrative directives is examined in this report. A random sample of 200 elementary school teachers in Mississippi received mailed questionnaires, of which 158, or 79 percent, responded. Survey instruments included the Wilkes and Blackbourn Zones of…

  5. Pathways to Adult Sexual Revictimization: Direct and Indirect Behavioral Risk Factors across the Lifespan

    ERIC Educational Resources Information Center

    Fargo, Jamison D.

    2009-01-01

    The purpose of this study is to investigate direct and indirect social and behavioral risk factors for adult sexual revictimization. Participants include 147 adult, predominantly African American (88%) women, 59% of whom had a documented history of child sexual abuse. Participants are interviewed in adulthood about adolescent and adult sexual…

  6. Factors affecting the establishment of direct-seeded pine on surface-mine spoils

    Treesearch

    William T. Plass

    1974-01-01

    In a greenhouse study the emergence, survival, and growth of seven species of pine were related to chemical and textural characteristics of 12 Kentucky spoils. The results identify three factors that may affect the establishment of direct-seeded pine on surface-mine spoils. First, fine-textured spoil material may restrict seedling emergence. Coarse-textured sandstones...

  7. High Dietary Fructose: Direct or Indirect Dangerous Factors Disturbing Tissue and Organ Functions.

    PubMed

    Zhang, Dong-Mei; Jiao, Rui-Qing; Kong, Ling-Dong

    2017-03-29

    High dietary fructose is a major contributor to insulin resistance and metabolic syndrome, disturbing tissue and organ functions. Fructose is mainly absorbed into systemic circulation by glucose transporter 2 (GLUT2) and GLUT5, and metabolized in liver to produce glucose, lactate, triglyceride (TG), free fatty acid (FFA), uric acid (UA) and methylglyoxal (MG). Its extrahepatic absorption and metabolism also take place. High levels of these metabolites are the direct dangerous factors. During fructose metabolism, ATP depletion occurs and induces oxidative stress and inflammatory response, disturbing functions of local tissues and organs to overproduce inflammatory cytokine, adiponectin, leptin and endotoxin, which act as indirect dangerous factors. Fructose and its metabolites directly and/or indirectly cause oxidative stress, chronic inflammation, endothelial dysfunction, autophagy and increased intestinal permeability, and then further aggravate the metabolic syndrome with tissue and organ dysfunctions. Therefore, this review addresses fructose-induced metabolic syndrome, and the disturbance effects of direct and/or indirect dangerous factors on the functions of liver, adipose, pancreas islet, skeletal muscle, kidney, heart, brain and small intestine. It is important to find the potential correlations between direct and/or indirect risk factors and healthy problems under excess dietary fructose consumption.

  8. Pathways to Adult Sexual Revictimization: Direct and Indirect Behavioral Risk Factors across the Lifespan

    ERIC Educational Resources Information Center

    Fargo, Jamison D.

    2009-01-01

    The purpose of this study is to investigate direct and indirect social and behavioral risk factors for adult sexual revictimization. Participants include 147 adult, predominantly African American (88%) women, 59% of whom had a documented history of child sexual abuse. Participants are interviewed in adulthood about adolescent and adult sexual…

  9. Monte Carlo direct view factor and generalized radiative heat transfer programs

    NASA Technical Reports Server (NTRS)

    Mc Williams, J. L.; Scates, J. H.

    1969-01-01

    Computer programs find the direct view factor from one surface segment to another using the Monte carlo technique, and the radioactive-transfer coefficients between surface segments. An advantage of the programs is the great generality of problems treatable and rapidity of solution from problem conception to receipt of results.

  10. Factors Affecting Long-Term-Care Residents' Decision-Making Processes as They Formulate Advance Directives

    ERIC Educational Resources Information Center

    Lambert, Heather C.; McColl, Mary Ann; Gilbert, Julie; Wong, Jiahui; Murray, Gale; Shortt, Samuel E. D.

    2005-01-01

    Purpose: The purpose of this study was to describe factors contributing to the decision-making processes of elderly persons as they formulate advance directives in long-term care. Design and Methods: This study was qualitative, based on grounded theory. Recruitment was purposive and continued until saturation was reached. Nine residents of a…

  11. Direct access: factors that affect physical therapist practice in the state of Ohio.

    PubMed

    McCallum, Christine A; DiAngelis, Tom

    2012-05-01

    Direct access to physical therapist services is permitted by law in the majority of states and across all practice settings. Ohio enacted such legislation in 2004; however, it was unknown how direct access had affected actual clinical practice. The purpose of this study was to describe physical therapist and physical therapist practice environment factors that affect direct access practice. A 2-phase, mixed-method descriptive study was conducted. In the first phase, focus group interviews with 32 purposively selected physical therapists were completed, which resulted in 8 themes for an electronically distributed questionnaire. In the second phase, survey questionnaires were distributed to physical therapists with an e-mail address on file with the Ohio licensing board. An adjusted return rate of 23% was achieved. Data were analyzed for descriptive statistics. A constant comparative method assessed open-ended questions for common themes and patterns. Thirty-one percent of the respondents reported using direct access in physical therapist practice; however, 80% reported they would practice direct access if provided the opportunity. Physical therapists who practiced direct access were more likely to be in practice 6 years or more and hold advanced degrees beyond the entry level, were American Physical Therapy Association members, and had supportive management and organizational practice policies. The direct access physical therapist practice was generally a locally owned suburban private practice or a school-based clinic that saw approximately 6% to 10% of its patients by direct access. The majority of patients treated were adults with musculoskeletal or neuromuscular impairments. Nonresponse from e-mail may be associated with sample frame bias. Implementation of a direct access physical therapist practice model is evident in Ohio. Factors related to reimbursement and organizational policy appear to impede the process.

  12. Tissue factor-driven thrombin generation and inflammation in atherosclerosis.

    PubMed

    ten Cate, Hugo

    2012-05-01

    The transmembrane receptor tissue factor is a prominent protein expressed at macrophages and smooth muscle cells within human atherosclerotic lesions. While many coagulation proteins are detectable in atherosclerosis, a locally active thrombin and fibrin generating molecular machinery may be instrumental in manipulating cellular functions involved in atherogenesis. These include inflammation, angiogenesis and cell proliferation. Indeed, many experimental studies in mice show a correlation between hypercoagulability and increased atherosclerosis. In mice, the amount of atherosclerosis and/or the plaque phenotype, appear to be modifiable by specific anticoagulant interventions. While attempts to vary tissue factor level in the vasculature does not directly reduce plaque burden, the overexpression of tissue factor pathway inhibitor attenuates thrombogenicity and neo intima formation in mice. Moreover, inhibition of factor Xa or thrombin with novel selective agents, including rivaroxaban and dabigatran, inhibits inflammation associated with atherosclerosis in apoE(-/-) mice. The potential to modify a complex chronic disease like atherosclerosis with novel selective anticoagulants merits further clinical study.

  13. Direct and Indirect Links between Peer Factors and Adolescent Adjustment Difficulties

    PubMed Central

    Houltberg, Benjamin J.; Cui, Lixian; Bosler, Cara D.; Morris, Amanda Sheffield; Silk, Jennifer S.

    2016-01-01

    The purpose of the current investigation was to examine the role of emotion regulation in the link between peer factors and adolescent adjustment difficulties. The sample consisted of 206 adolescents (ages 10–18 years) and parents. Peer factors (i.e., peer antisocial behavior, peer co-rumination, peer emotion regulation) and youth depressive symptoms were based on youth reports. Youth emotion regulation and antisocial behavior were assessed using parent and youth ratings. Results showed that peer antisocial behavior was directly (but not indirectly) related to youth antisocial behavior and depressive symptoms, whereas peer emotion regulation was indirectly (but not directly) related to both adolescent outcomes. In addition, peer co-rumination was indirectly related to youth antisocial behavior and directly and indirectly related to youth depressive symptoms. In general, the results indicated little evidence of moderation by adolescent age, sex, or ethnic differences. Implications for peer relationships as socialization contexts are discussed. PMID:26893530

  14. Direct and indirect effects of biological factors on extinction risk in fossil bivalves

    PubMed Central

    Harnik, Paul G.

    2011-01-01

    Biological factors, such as abundance and body size, may contribute directly to extinction risk and indirectly through their influence on other biological characteristics, such as geographic range size. Paleontological data can be used to explicitly test many of these hypothesized relationships, and general patterns revealed through analysis of the fossil record can help refine predictive models of extinction risk developed for extant species. Here, I use structural equation modeling to tease apart the contributions of three canonical predictors of extinction—abundance, body size, and geographic range size—to the duration of bivalve species in the early Cenozoic marine fossil record of the eastern United States. I find that geographic range size has a strong direct effect on extinction risk and that an apparent direct effect of abundance can be explained entirely by its covariation with geographic range. The influence of geographic range on extinction risk is manifest across three ecologically disparate bivalve clades. Body size also has strong direct effects on extinction risk but operates in opposing directions in different clades, and thus, it seems to be decoupled from extinction risk in bivalves as a whole. Although abundance does not directly predict extinction risk, I reveal weak indirect effects of both abundance and body size through their positive influence on geographic range size. Multivariate models that account for the pervasive covariation between biological factors and extinction are necessary for assessing causality in evolutionary processes and making informed predictions in applied conservation efforts. PMID:21808004

  15. Direct and indirect effects of biological factors on extinction risk in fossil bivalves.

    PubMed

    Harnik, Paul G

    2011-08-16

    Biological factors, such as abundance and body size, may contribute directly to extinction risk and indirectly through their influence on other biological characteristics, such as geographic range size. Paleontological data can be used to explicitly test many of these hypothesized relationships, and general patterns revealed through analysis of the fossil record can help refine predictive models of extinction risk developed for extant species. Here, I use structural equation modeling to tease apart the contributions of three canonical predictors of extinction--abundance, body size, and geographic range size--to the duration of bivalve species in the early Cenozoic marine fossil record of the eastern United States. I find that geographic range size has a strong direct effect on extinction risk and that an apparent direct effect of abundance can be explained entirely by its covariation with geographic range. The influence of geographic range on extinction risk is manifest across three ecologically disparate bivalve clades. Body size also has strong direct effects on extinction risk but operates in opposing directions in different clades, and thus, it seems to be decoupled from extinction risk in bivalves as a whole. Although abundance does not directly predict extinction risk, I reveal weak indirect effects of both abundance and body size through their positive influence on geographic range size. Multivariate models that account for the pervasive covariation between biological factors and extinction are necessary for assessing causality in evolutionary processes and making informed predictions in applied conservation efforts.

  16. Literacy and Race as Risk Factors to Low Rates of Advance Directives Among Older Adults

    PubMed Central

    Waite, Katherine R.; Federman, Alex D.; McCarthy, Danielle M.; Sudore, Rebecca; Curtis, Laura M.; Baker, David W.; Wilson, Elizabeth A. H.; Hasnain-Wynia, Romana; Wolf, Michael S.; Paasche-Orlow, Michael K.

    2012-01-01

    Background Advance directives are documented instructions by a patient to ensure their medical care preferences are fulfilled in the event they cannot communicate with clinicians or family members. Objectives The current study examined the relationship between literacy and other patient level factors on having an advance directive. Design Face-to-face structured interview. Setting Participants were recruited from either an academic general internal medicine clinic or one of four federally qualified health centers in Chicago. Participants 784 adults ages 55 to 74. Measurements Assessment of participant literacy, sociodemographic factors, and having an advance directive for medical care. Results Having an advanced directive was reported by 12.4% of subjects with low literacy, 26.6% of those with marginal literacy, and 49.5% of those with adequate literacy (p<0.001). In multivariable analyses, both literacy and race were independently associated with a lower likelihood of having an advance directive. Specifically, people with limited literacy and African Americans were less likely to have an advance directive (RR, 0.45; 95% CI, 0.22–0.95; RR, 0.64; 95% CI: 0.47–0.88, respectively). Exploratory analyses exhibited that there was not a significant interaction between the effect of literacy and race. Conclusion Limited literacy and African American race were significant risk factors to not having an advance directive in this cohort of older patients. Literacy and race likely represent two separate but important causal pathways that need to be understood to improve how the health care system ascertains and protects patients’ advanced care preferences. PMID:23379361

  17. Activation of factor X by rat hepatocytes

    SciTech Connect

    Willingham, A.K.; Matschiner, J.T.

    1986-05-01

    Synthesis and secretion of blood coagulation factor X was studied in hepatocytes prepared by perfusion of rat livers with collagenase. Hepatocytes were incubated in the presence of vitamin K and /sup 3/H-leucine for up to 4h at 37/sup 0/C. Factor X was isolated from the incubation medium by immunochemical techniques and analyzed by SDS-PAGE. The recovered /sup 3/H-labeled proteins migrated, after reduction of disulfides, as two polypeptide chains with apparent molecular weights (M/sub r/) of approximately 42,000 and 22,000 representing the heavy and light chains of factor X respectively. The apparent M/sub r/ of the heavy chain was about 10,000 daltons lighter than seen with the heavy chain of factor X isolated from rat plasma and was more characteristic of the heavy chain of factor Xa. When the levels of factor X secreted by hepatocytes were determined by clotting assays, activity was present as factor Xa. Also, when purified plasma factor X was added to incubations of hepatocytes (>95% parenchymal cells) the added factor X was rapidly converted to factor Xa. Plasma membranes prepared from isolated hepatocytes or from liver homogenates contained an enzyme that converted factor X to factor Xa in a calcium dependent reaction. The physiological significance of a factor X activating enzyme on hepatocyte plasma membranes is not clear.

  18. The ATLAS ACS 2-TIMI 51 trial and the burden of missing data: (Anti-Xa Therapy to Lower Cardiovascular Events in Addition to Standard Therapy in Subjects With Acute Coronary Syndrome ACS 2-Thrombolysis In Myocardial Infarction 51).

    PubMed

    Krantz, Mori J; Kaul, Sanjay

    2013-08-27

    Rivaroxaban is a factor Xa inhibitor that was recently reviewed by the Food and Drug Administration as a potential therapy to reduce the risk of recurrent atherothrombotic events in patients with acute coronary syndromes. Approval of this drug would represent a paradigm shift away from dual antiplatelet therapy toward long-term triple antithrombotic therapy. However, to date, no other experimental anticoagulant agent has demonstrated a favorable risk-benefit profile in this population, in part because of the expected increased risk in major bleeding by combining aspirin, a P2Y12 receptor inhibitor, and an anticoagulant. Approvability of rivaroxaban was considered largely on the basis of the ATLAS ACS 2-TIMI 51 (Anti-Xa Therapy to Lower Cardiovascular Events in Addition to Standard Therapy in Subjects With Acute Coronary Syndrome ACS 2-Thrombolysis In Myocardial Infarction 51) trial, which demonstrated a significant reduction in a composite of cardiovascular death, myocardial infarction, and stroke. Although the primary efficacy endpoint was met, a substantial amount of missing data was observed. We discuss the impact of missing data in this trial, its implications for informative censoring of safety events (major bleeding), and implications for future cardiovascular outcomes trials. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  19. Form factor effects in the direct detection of isospin-violating dark matter

    SciTech Connect

    Zheng, Hao; Zhang, Zhen; Chen, Lie-Wen E-mail: malkuth@sjtu.edu.cn

    2014-08-01

    Isospin-violating dark matter (IVDM) provides a possible mechanism to ameliorate the tension among recent direct detection experiments. For IVDM, we demonstrate that the results of direct detection experiments based on neutron-rich target nuclei may depend strongly on the density dependence of the symmetry energy which is presently largely unknown and controls the neutron skin thickness that reflects the relative difference of neutron and proton form factors in the neutron-rich nuclei. In particular, using the neutron and proton form factors obtained from Skyrme-Hartree-Fock calculations by varying the symmetry energy within the uncertainty region set by the latest model-independent measurement of the neutron skin thickness of {sup 208}Pb from PREX experiment at JLab, we find that, for IVDM with neutron-to-proton coupling ratio fixed to f{sub n}/f{sub p}=-0.7, the form factor effect may enhance the sensitivity of Xe-based detectors (e.g., XENON100 and LUX) to the DM-proton cross section by a factor of 3 in the DM mass region constrained by CMDS-II(Si) and even by more than an order of magnitude for heavy DM with mass larger than 80 GeV, compared with the results using the empirical Helm form factor. Our results further indicate that the form factor effect can significantly modify the recoil spectrum of Xe-based detectors for heavy IVDM with f{sub n}/f{sub p}=-0.7.

  20. Form factor effects in the direct detection of isospin-violating dark matter

    NASA Astrophysics Data System (ADS)

    Zheng, Hao; Zhang, Zhen; Chen, Lie-Wen

    2014-08-01

    Isospin-violating dark matter (IVDM) provides a possible mechanism to ameliorate the tension among recent direct detection experiments. For IVDM, we demonstrate that the results of direct detection experiments based on neutron-rich target nuclei may depend strongly on the density dependence of the symmetry energy which is presently largely unknown and controls the neutron skin thickness that reflects the relative difference of neutron and proton form factors in the neutron-rich nuclei. In particular, using the neutron and proton form factors obtained from Skyrme-Hartree-Fock calculations by varying the symmetry energy within the uncertainty region set by the latest model-independent measurement of the neutron skin thickness of 208Pb from PREX experiment at JLab, we find that, for IVDM with neutron-to-proton coupling ratio fixed to fn/fp=-0.7, the form factor effect may enhance the sensitivity of Xe-based detectors (e.g., XENON100 and LUX) to the DM-proton cross section by a factor of 3 in the DM mass region constrained by CMDS-II(Si) and even by more than an order of magnitude for heavy DM with mass larger than 80 GeV, compared with the results using the empirical Helm form factor. Our results further indicate that the form factor effect can significantly modify the recoil spectrum of Xe-based detectors for heavy IVDM with fn/fp=-0.7.

  1. Spitzer IRS observations of the XA region in the cygnus loop supernova remnant

    SciTech Connect

    Sankrit, Ravi; Bautista, Manuel; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.

    2014-05-20

    We report on spectra of two positions in the XA region of the Cygnus Loop supernova remnant obtained with the InfraRed Spectrograph on the Spitzer Space Telescope. The spectra span the 10-35 μm wavelength range, which contains a number of collisionally excited forbidden lines. These data are supplemented by optical spectra obtained at the Whipple Observatory and an archival UV spectrum from the International Ultraviolet Explorer. Coverage from the UV through the IR provides tests of shock wave models and tight constraints on model parameters. Only lines from high ionization species are detected in the spectrum of a filament on the edge of the remnant. The filament traces a 180 km s{sup –1} shock that has just begun to cool, and the oxygen to neon abundance ratio lies in the normal range found for Galactic H II regions. Lines from both high and low ionization species are detected in the spectrum of the cusp of a shock-cloud interaction, which lies within the remnant boundary. The spectrum of the cusp region is matched by a shock of about 150 km s{sup –1} that has cooled and begun to recombine. The post-shock region has a swept-up column density of about 1.3 × 10{sup 18} cm{sup –2}, and the gas has reached a temperature of 7000-8000 K. The spectrum of the Cusp indicates that roughly half of the refractory silicon and iron atoms have been liberated from the grains. Dust emission is not detected at either position.

  2. Spitzer IRS Observations of the XA Region in the Cygnus Loop Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Sankrit, Ravi; Raymond, John C.; Bautista, Manuel; Gaetz, Terrance J.; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.

    2014-05-01

    We report on spectra of two positions in the XA region of the Cygnus Loop supernova remnant obtained with the InfraRed Spectrograph on the Spitzer Space Telescope. The spectra span the 10-35 μm wavelength range, which contains a number of collisionally excited forbidden lines. These data are supplemented by optical spectra obtained at the Whipple Observatory and an archival UV spectrum from the International Ultraviolet Explorer. Coverage from the UV through the IR provides tests of shock wave models and tight constraints on model parameters. Only lines from high ionization species are detected in the spectrum of a filament on the edge of the remnant. The filament traces a 180 km s-1 shock that has just begun to cool, and the oxygen to neon abundance ratio lies in the normal range found for Galactic H II regions. Lines from both high and low ionization species are detected in the spectrum of the cusp of a shock-cloud interaction, which lies within the remnant boundary. The spectrum of the cusp region is matched by a shock of about 150 km s-1 that has cooled and begun to recombine. The post-shock region has a swept-up column density of about 1.3 × 1018 cm-2, and the gas has reached a temperature of 7000-8000 K. The spectrum of the Cusp indicates that roughly half of the refractory silicon and iron atoms have been liberated from the grains. Dust emission is not detected at either position. Based on observations made with the Spitzer Space Telescope.

  3. Geometrical gauge factor of directional electric potential drop sensors for creep monitoring

    SciTech Connect

    Madhi, E.; Nagy, P. B.

    2011-06-23

    Directional electric potential drop measurements can be exploited for in-situ monitoring of creep in metals. The sensor monitors the variation in the ratio of the resistances measured simultaneously in the axial and lateral directions using a square-electrode configuration. This technique can efficiently separate the mostly isotropic common part of the resistivity variation caused by reversible temperature variations from the mostly anisotropic differential part caused by direct geometrical and indirect material effects of creep. Initially, this ratio is roughly proportional to the axial creep strain, while at later stages, the resistance ratio increases even faster with creep strain because of the formation of directional discontinuities such as preferentially oriented grain boundary cavities and multiple-site cracks in the material. Similarly to ordinary strain gauges, the relative sensitivity of the sensor is defined as a gauge factor that can be approximated as a sum of geometrical and material parts. This work investigated the geometrical gauge factor by analytical and experimental means. We found that under uniaxial stress square-electrode sensors exhibit geometrical gauge factors of about 4 and 5 in the elastic and plastic regimes, respectively, i.e., more than twice those of conventional strain gauges. Experimental results obtained on 304 stainless steel using a square-electrode electric potential drop creep sensor agree well with our theoretical predictions.

  4. Human projected area factors for detailed direct and diffuse solar radiation analysis.

    PubMed

    Kubaha, K; Fiala, D; Toftum, J; Taki, A H

    2004-11-01

    Projected area factors for individual segments of the standing and sedentary human body were modelled for both direct and diffuse solar radiation using detailed 3D geometry and radiation models. The local projected area factors with respect to direct short-wave radiation are a function of the solar azimuth angle (alpha) between 0 degrees < alpha<360 degrees and the solar altitude (beta) angles between -90 degrees < beta<+90 degrees . In case of diffuse solar radiation from the isotropic sky the local human projected area factors were modelled as a function of the ground albedo (rho) ranging between 0< rho<1. The model was validated against available experimental data and showed good general agreement with projected area factors measured for both the human body as a whole and for local quantities. Scientists can use the equations to predict the inhomogeneous irradiation and absorption of direct and diffuse solar radiation and UV-radiation at surfaces of the human body. In conjunction with detailed multi-node models of human thermoregulation the equations can be used to predict the physiological implications of solar radiation and outdoor weather conditions on humans.

  5. Direct conversion of human fibroblasts into functional osteoblasts by defined factors.

    PubMed

    Yamamoto, Kenta; Kishida, Tsunao; Sato, Yoshiki; Nishioka, Keisuke; Ejima, Akika; Fujiwara, Hiroyoshi; Kubo, Toshikazu; Yamamoto, Toshiro; Kanamura, Narisato; Mazda, Osam

    2015-05-12

    Osteoblasts produce calcified bone matrix and contribute to bone formation and remodeling. In this study, we established a procedure to directly convert human fibroblasts into osteoblasts by transducing some defined factors and culturing in osteogenic medium. Osteoblast-specific transcription factors, Runt-related transcription factor 2 (Runx2), and Osterix, in combination with Octamer-binding transcription factor 3/4 (Oct4) and L-Myc (RXOL) transduction, converted ∼ 80% of the fibroblasts into osteocalcin-producing cells. The directly converted osteoblasts (dOBs) induced by RXOL displayed a similar gene expression profile as normal human osteoblasts and contributed to bone repair after transplantation into immunodeficient mice at artificial bone defect lesions. The dOBs expressed endogenous Runx2 and Osterix, and did not require continuous expression of the exogenous genes to maintain their phenotype. Another combination, Oct4 plus L-Myc (OL), also induced fibroblasts to produce bone matrix, but the OL-transduced cells did not express Osterix and exhibited a more distant gene expression profile to osteoblasts compared with RXOL-transduced cells. These findings strongly suggest successful direct reprogramming of fibroblasts into functional osteoblasts by RXOL, a technology that may provide bone regeneration therapy against bone disorders.

  6. Factor structure of overall autobiographical memory usage: the directive, self and social functions revisited.

    PubMed

    Rasmussen, Anne S; Habermas, Tilmann

    2011-08-01

    According to theory, autobiographical memory serves three broad functions of overall usage: directive, self, and social. However, there is evidence to suggest that the tripartite model may be better conceptualised in terms of a four-factor model with two social functions. In the present study we examined the two models in Danish and German samples, using the Thinking About Life Experiences Questionnaire (TALE; Bluck, Alea, Habermas, & Rubin, 2005), which measures the overall usage of the three functions generalised across concrete memories. Confirmatory factor analysis supported the four-factor model and rejected the theoretical three-factor model in both samples. The results are discussed in relation to cultural differences in overall autobiographical memory usage as well as sharing versus non-sharing aspects of social remembering.

  7. Determination of stress intensity factor with direct stress approach using finite element analysis

    NASA Astrophysics Data System (ADS)

    Ji, X.; Zhu, F.; He, P. F.

    2017-03-01

    In this article, a direct stress approach based on finite element analysis to determine the stress intensity factor is improved. Firstly, by comparing the rigorous solution against the asymptotic solution for a problem of an infinite plate embedded a central crack, we found that the stresses in a restrictive interval near the crack tip given by the rigorous solution can be used to determine the stress intensity factor, which is nearly equal to the stress intensity factor given by the asymptotic solution. Secondly, the crack problem is solved numerically by the finite element method. Depending on the modeling capability of the software, we designed an adaptive mesh model to simulate the stress singularity. Thus, the stress result in an appropriate interval near the crack tip is fairly approximated to the rigorous solution of the corresponding crack problem. Therefore, the stress intensity factor may be calculated from the stress distribution in the appropriate interval, with a high accuracy.

  8. The RNA polymerase I transcription factor, upstream binding factor, interacts directly with the TATA box-binding protein.

    PubMed

    Kwon, H; Green, M R

    1994-12-02

    The accurate transcription of human rRNA genes by RNA polymerase I requires two transcription factors, upstream binding factor (UBF) and promoter selectivity factor (SL1). Human SL1 (hSL1) is a multisubunit complex, one of whose components is TATA box-binding protein (TBP). hSL1 binds to the core region of the rRNA promoter, but does so inefficiently in the absence of human UBF (hUBF). hUBF interacts with the upstream control element of the rRNA promoter and facilitates binding of hSL1. The molecular basis by which hUBF increases binding of hSL1 remains to be elucidated. In this report, we use an immobilized protein binding assay to identify and purify a 95-kDa TBP-binding polypeptide. Microsequence analysis reveals that the 95-kDa TBP-binding protein is hUBF. We show that hUBF is stably associated with TBP and is present in large TBP-containing complexes. Our results indicate that the cooperative binding of hUBF and hSL1 on the rRNA promoter is mediated by direct interaction between hUBF and TBP. We also provide evidence that hUBF associates with TFIID, a TBP-containing RNA polymerase II transcription factor.

  9. Variation of directional reflectance factors with structural changes of a developing alfalfa canopy

    NASA Technical Reports Server (NTRS)

    Kirchner, J. A.; Kimes, D. S.; Mcmurtrey, J. E., III

    1982-01-01

    Directional reflectance factors of an alfalfa canopy were determined and related to canopy structure, agronomic variables, and irradiance conditions at four periods during a cutting cycle. Nadir and off-nadir reflectance factors decreased with increasing biomass in Thematic Mapper band 3(0.63-0.69 micrometer) and increased with increasing biomass in band 4(0.76-0.90 micrometer). The sensor view angle had less impact on perceived reflectance as the alfalfa progressed from an erectophile canopy of stems after harvest to a near planophile canopy of leaves at maturity. Studies of directional reflectance are needed for testing and upgrading vegetation canopy models and to aid in the complex interpretation problems presented by aircraft scanners and pointable satellites where illumination and viewing geometries may vary widely. Distinct changes in the patterns of radiance observed by a sensor as structural and biomass changes occur are keys to monitoring the growth and condition of crops.

  10. Risk Factors for and Behavioral Consequences of Direct Versus Indirect Exposure to Violence.

    PubMed

    Zimmerman, Gregory M; Posick, Chad

    2016-01-01

    Research suggests that direct exposure (personal victimization) and indirect exposure (witnessing or hearing about the victimization of a family member, friend, or neighbor) to violence are correlated. However, questions remain about the co-occurrence of these phenomena within individuals. We used data on 1915 youths (with an average age of 12 years at baseline) from the Project on Human Development in Chicago Neighborhoods to examine this issue. Results indicated that youths who tended to be personally victimized were also likely to witness violence; conversely, youths who disproportionately witnessed violence were relatively unlikely to experience personal victimization. In addition, direct and indirect exposures to violence were associated with subsequent adverse outcomes in similar ways. The key distinguishing factor was, rather, the cumulative level of violence (both direct and indirect) to which youths were exposed.

  11. Defining the Minimal Factors Required for Erythropoiesis through Direct Lineage Conversion.

    PubMed

    Capellera-Garcia, Sandra; Pulecio, Julian; Dhulipala, Kishori; Siva, Kavitha; Rayon-Estrada, Violeta; Singbrant, Sofie; Sommarin, Mikael N E; Walkley, Carl R; Soneji, Shamit; Karlsson, Göran; Raya, Ángel; Sankaran, Vijay G; Flygare, Johan

    2016-06-14

    Erythroid cell commitment and differentiation proceed through activation of a lineage-restricted transcriptional network orchestrated by a group of well characterized genes. However, the minimal set of factors necessary for instructing red blood cell (RBC) development remains undefined. We employed a screen for transcription factors allowing direct lineage reprograming from fibroblasts to induced erythroid progenitors/precursors (iEPs). We show that Gata1, Tal1, Lmo2, and c-Myc (GTLM) can rapidly convert murine and human fibroblasts directly to iEPs. The transcriptional signature of murine iEPs resembled mainly that of primitive erythroid progenitors in the yolk sac, whereas addition of Klf1 or Myb to the GTLM cocktail resulted in iEPs with a more adult-type globin expression pattern. Our results demonstrate that direct lineage conversion is a suitable platform for defining and studying the core factors inducing the different waves of erythroid development. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  12. Material gauge factor of directional electric potential drop sensors for creep monitoring

    SciTech Connect

    Madhi, E.; Nagy, P. B.

    2011-06-23

    Directional electric potential drop measurements can be exploited for in-situ monitoring of creep in metals. The sensor monitors the variation in the ratio of the resistances measured simultaneously in the axial and lateral directions using a square-electrode configuration. This method can efficiently separate the mostly isotropic common part of the resistivity variation caused by reversible temperature variations from the mostly anisotropic differential part caused by direct geometrical (size and shape) and indirect material (resistivity) effects of creep. Similarly to ordinary strain gauges, the relative sensitivity of the sensor is defined as a gauge factor that can be approximated as the sum of geometrical and material parts. Initially, subtle material changes produce weak electric anisotropy via reversible and irreversible piezoresistivity due to elastic and plastic strains, respectively. At high temperature, much stronger irreversible resistivity changes also occur due to preferentially aligned clusters of cavities developing along grain boundaries approximately perpendicular to the applied stress and subsequent cracks forming between these cavities. The ensuing electric anisotropy is detected by the directional sensor. Although the material effects remain smaller than the geometrical ones up to the initiation of preferentially oriented cracks, later the material gauge factor sharply increases and close to rupture can reach a value of more than 10.

  13. Insect cell-based expression and characterization of a single-chain variable antibody fragment directed against blood coagulation factor VIII.

    PubMed

    Kurasawa, James H; Shestopal, Svetlana A; Jha, Naveen K; Ovanesov, Mikhail V; Lee, Timothy K; Sarafanov, Andrey G

    2013-04-01

    A recombinant single-chain variable antibody fragment (scFv) KM33 was previously described as a ligand that can inhibit the function of blood coagulation factor VIII (FVIII). This scFv was previously derived from an individual with anti-FVIII antibodies manifested in FVIII functional deficiency (Hemophilia A) and expressed in bacteria. In the present work, we describe an alternative approach for fast and easy production of KM33 in insect cells (Spodoptera frugiperda). The KM33 gene was codon-optimized and expressed in secreted form using a baculovirus system. The protein was isolated using metal-affinity and size-exclusion chromatography to purity of about 96% and yield of 0.4-1.2 mg per 120 mL of culture, based on several independent expression experiments. In a binding assay using surface plasmon resonance, the insect cell-derived KM33 (iKM33) was qualified as a high-affinity ligand for FVIII. Epitope specificity of iKM33 on FVIII (C1 domain) was confirmed by testing the binding with a relevant mutant of FVIII. In several FVIII functional tests (factor Xa generation, APTT clotting, thrombin generation and video microscopy clot growth assays), iKM33 strongly inhibited FVIII activity in accordance with the clinical effect of the parental antibody. Therefore, the expressed protein was concluded to be fully functional and applicable in various assays with FVIII. Published by Elsevier Inc.

  14. Cerebral Venous Thromboembolism in Antiphospholipid Syndrome Successfully Treated with the Combined Use of an Anti-Xa Inhibitor and Corticosteroid.

    PubMed

    Sugie, Masayuki; Iizuka, Natsuko; Shimizu, Yuki; Ichikawa, Hiroo

    2015-01-01

    We herein report a case presenting with cerebral venous sinus thrombosis (CVST) associated with primary antiphospholipid syndrome (APS). The patient developed recurrent CVST followed by a hemorrhagic ischemic stroke despite the use of warfarin during the appropriate therapeutic window. Thus, we substituted warfarin to rivaroxaban with prednisolone and obtained a good clinical course. In addition to the effect of prednisolone of inhibiting elevated lupus anticoagulants and the recurrence of arterial thrombosis, rivaroxaban may prevent CVST and inhibit hypercoagulability induced by corticosteroids. The combination of an anti-Xa inhibitor and corticosteroid may be an alternative treatment for CVST and arterial thrombus with warfarin-resistant APS.

  15. Exposure to aggressive behaviour and burnout in direct support providers: The role of positive work factors.

    PubMed

    Hensel, Jennifer M; Lunsky, Yona; Dewa, Carolyn S

    2014-11-11

    Many direct support providers (DSPs) are exposed to aggressive behaviour in their work supporting adults with developmental disabilities service recipients. This is a work environment factor that has been linked to job burnout. The objective of this study was to examine the impact of positive work factors on emotional exhaustion (EE) among DSPs who are exposed to aggressive behaviour. Survey responses from 671 DSPs who were working in community service settings for adults with developmental disabilities, and were exposed to aggressive behaviour at least monthly were examined. Hierarchical linear regression examined the direct contribution and moderating role of positive work factors (self-efficacy for dealing with aggression and work contributions) on EE measured with the Maslach Burnout Inventory-Human Services Survey, after controlling for demographics, occupational variables, exposure to aggression and negative emotional reactions to aggression. Results showed that younger age, more experience, more depression/anger emotions in response to aggression, lower self-efficacy and low positive work contributions were significantly associated with EE. Positive work motivation was a moderator of exposure to aggression and EE. When work motivations were low, DSPs were more negatively affected by higher exposure to aggression. These findings suggest that in addition to addressing the negative emotional reactions to the aggressive behaviour encountered at work, it is also important to foster positive work factors which may be protective against EE. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Co-immobilization of gradient-patterned growth factors for directed cell migration

    PubMed Central

    Stefonek-Puccinelli, Tracy Jane; Masters, Kristyn S.

    2009-01-01

    Cell migration is critically important for the repair of chronic wounds, which cost billions of dollars each year to treat and can lead to serious complications, including amputation and death. Growth factors, including epidermal growth factor (EGF) and insulin-like growth factor (IGF-1), are known to be deficient in chronic wounds; unfortunately, traditional delivery of soluble growth factors to wounds is expensive and complicated by their degradation. We have previously shown that directed and accelerated keratinocyte migration could be achieved by creating immobilized gradients of EGF. In this work, we have optimized EGF gradients for cell migration, synthesized and characterized gradient patterns of IGF-1, and tested for migration synergy upon combination of EGF and IGF-1 patterns. An optimal EGF concentration and pattern were identified, resulting in migration that was almost 10-fold that achieved on unpatterned controls. Immobilization of IGF-1 gradients also accelerated and directed keratinocyte migration (p<0.05), however, no difference in migration was found across various IGF-1 concentrations or gradient patterns. Although combining EGF with IGF-1 patterns did not accelerate migration beyond levels achieved using EGF alone, these methods can be applied to create other types of multi-component gradients that will ultimately be utilized to create 3-D bioactive wound dressings. PMID:18850272

  17. Direct oral anticoagulant medications in calciphylaxis.

    PubMed

    King, Brian J; El-Azhary, Rokea A; McEvoy, Marian T; Shields, Raymond C; McBane, Robert D; McCarthy, James T; Davis, Mark D P

    2017-10-01

    Recent studies suggest that calciphylaxis is a thrombotic condition in which arteriolar thrombosis leads to painful skin infarcts and consequent morbidity and mortality. Paradoxically, warfarin is implicated as a risk factor for calciphylaxis. Our objective is to report the use of oral direct thrombin and factor Xa inhibitors (termed direct oral anticoagulants [DOACs]) in patients with calciphylaxis. We retrospectively reviewed records of 16 patients with calciphylaxis who received concomitant administration of novel anticoagulants. Patient data, including demographics, comorbidities, other treatments, and adverse events, were abstracted from the health records. Eleven patients (69%) had chronic kidney disease (stage ≥3A), and eight (50%) received dialysis. Apixaban was the most frequently used agent (n = 11 [69%]). Dabigatran (n = 4 [25%]) and rivaroxaban (n = 2 [13%]) were reserved for patients with mild renal impairment (stage ≤2). One clinically relevant but nonmajor bleeding event occurred. There were no major bleeding events. Nine patients (56%) were alive at last follow-up, and five (31%) had complete resolution of their calciphylaxis (mean follow-up, 523 days; range, 26-1884 days). DOACs were safe and well tolerated in patients with calciphylaxis, in this initial experience. Several patients had improvement or resolution of calciphylaxis in response to therapy that included DOACs. The degree of renal impairment should guide DOAC choice. Randomized trials are required to determine treatment efficacy. © 2017 The International Society of Dermatology.

  18. Transcription factors that directly regulate the expression of CSLA9 encoding mannan synthase in Arabidopsis thaliana.

    PubMed

    Kim, Won-Chan; Reca, Ida-Barbara; Kim, Yongsig; Park, Sunchung; Thomashow, Michael F; Keegstra, Kenneth; Han, Kyung-Hwan

    2014-03-01

    Mannans are hemicellulosic polysaccharides that have a structural role and serve as storage reserves during plant growth and development. Previous studies led to the conclusion that mannan synthase enzymes in several plant species are encoded by members of the cellulose synthase-like A (CSLA) gene family. Arabidopsis has nine members of the CSLA gene family. Earlier work has shown that CSLA9 is responsible for the majority of glucomannan synthesis in both primary and secondary cell walls of Arabidopsis inflorescence stems. Little is known about how expression of the CLSA9 gene is regulated. Sequence analysis of the CSLA9 promoter region revealed the presence of multiple copies of a cis-regulatory motif (M46RE) recognized by transcription factor MYB46, leading to the hypothesis that MYB46 (At5g12870) is a direct regulator of the mannan synthase CLSA9. We obtained several lines of experimental evidence in support of this hypothesis. First, the expression of CSLA9 was substantially upregulated by MYB46 overexpression. Second, electrophoretic mobility shift assay (EMSA) was used to demonstrate the direct binding of MYB46 to the promoter of CSLA9 in vitro. This interaction was further confirmed in vivo by a chromatin immunoprecipitation assay. Finally, over-expression of MYB46 resulted in a significant increase in mannan content. Considering the multifaceted nature of MYB46-mediated transcriptional regulation of secondary wall biosynthesis, we reasoned that additional transcription factors are involved in the CSLA9 regulation. This hypothesis was tested by carrying out yeast-one hybrid screening, which identified ANAC041 and bZIP1 as direct regulators of CSLA9. Transcriptional activation assays and EMSA were used to confirm the yeast-one hybrid results. Taken together, we report that transcription factors ANAC041, bZIP1 and MYB46 directly regulate the expression of CSLA9.

  19. [Factors affecting the DAPI fluorescence direct count in the tidal river sediment].

    PubMed

    Chen, Chen; Huang, Shan; Wu, Qun-he; Li, Rui-yi; Zhang, Ren-duo

    2010-08-01

    The factors affecting the DAPI (4', 6-diamidino-2-phenylidole) fluorescence direct count in the tidal river sediment were examined. Sediment samples were collected from the Guangzhou section of the Pearl River. Besides sediment texture and organic matter, an improved staining procedure and the involved parameters were analyzed. Results showed that the procedure with the sediment with 2000 fold dilution and ultrasonic water bath for 10 min, and with a final DAPI concentration of 10 microg x mL(-1) and staining time for more than 30 min produced the optimum results of DAPI direct count in the sediment. The total bacterial number was correlated to the proportion of the non-nucleoid-containing cells to the total bacterial number (r = 0.587, p = 0.004). The organic matter content also correlated to the ration. The clay content had a strong correlation with the organic matter, through which the clay content also affected the ratio. A multiple regression analysis between the ration versus the organic matter, the total bacterial number, and the clay content showed that the regression equation fit the measure values satisfactorily (r = 0.694). These results indicated that the above factors needed to be considered in the applications of the DAPI fluorescence direct counting method to the tidal river sediment.

  20. Effect of 3.2 vs. 3.8% sodium citrate concentration on anti-Xa levels for patients on therapeutic low molecular weight heparin.

    PubMed

    Payne, S; MacKinnon, K; Keeney, M; Morrow, B; Kovacs, M J

    2003-10-01

    In this study, we compared the effect of sodium citrate, a sample collection variable, on the anti-Xa levels of patients (n = 28) on dalteparin, a low molecular weight heparin. The median anti-Xa level for 3.2% sodium citrate was 0.235 U/ml while the median level for 3.8% sodium citrate was 0.230 U/ml. We conclude that different sodium citrate concentrations give statistically equivalent anti-Xa levels for the same samples. This conclusion is in contrast to the findings of the effect of sodium citrate concentration on International Normalized Ratio (INR) and activated partial-thromboplastin time (aPTT). In accordance with previous recommendations, we advocate the exclusive use of 3.2% sodium citrate in an effort to standardize coagulation testing.

  1. Environmental Determinants of Cardiovascular Diseases Risk Factors: A Qualitative Directed Content Analysis

    PubMed Central

    Sabzmakan, Leila; Mohammadi, Eesa; Morowatisharifabad, Mohammad Ali; Afaghi, Ahmad; Naseri, Mohammad Hassan; Mirzaei, Masoud

    2014-01-01

    Background: Cardiovascular diseases (CVDs) are the number one cause of death in the world. In most analyses of health problems, environment plays a significant and modifiable role in causing the problem either directly or indirectly through behavior. Objectives: This study aims to understand the patients and healthcare providers’ experiences about the environmental determinants of CVD risk factors based on the Precede Model. Patients and Methods: This qualitative study conducted over six months in 2012 at Diabetes Units of Health Centers associated with Alborz University of Medical Sciences and Health Services which is located in Karaj, Iran. The data were collected based on individual semi-structured interviews with 50 patients and 12 healthcare providers. Data analysis was performed simultaneous with data collection using the content analysis directed method. Results: Lack of behaviors like stress control, healthy eating and physical activity were the roots of the risk factors for CVD. The environmental factor is one of the barriers for conducting these behaviors. The environmental barriers included of structural environment including “availability and accessibility of health resources”, “new skills”, and “law and policies” which are located in enabling category and social environment including “social support”, “motivation to comply” and “consequences of behavior” which are located in reinforcing category. The most barriers to performing health behaviors were often structural. Conclusions: The environmental factors were barriers for doing healthy behaviors. These factors need to be considered to design health promotion interventions. Policymakers should not only focus on patients’ education but also should provide specific facilities to enhance economic, social and cultural status. PMID:25031848

  2. RNA-directed DNA methylation and plant development require an IWR1-type transcription factor.

    PubMed

    Kanno, Tatsuo; Bucher, Etienne; Daxinger, Lucia; Huettel, Bruno; Kreil, David P; Breinig, Frank; Lind, Marc; Schmitt, Manfred J; Simon, Stacey A; Gurazada, Sai Guna Ranjan; Meyers, Blake C; Lorkovic, Zdravko J; Matzke, Antonius J M; Matzke, Marjori

    2010-01-01

    RNA-directed DNA methylation (RdDM) in plants requires two RNA polymerase (Pol) II-related RNA polymerases, namely Pol IV and Pol V. A genetic screen designed to reveal factors that are important for RdDM in a developmental context in Arabidopsis identified DEFECTIVE IN MERISTEM SILENCING 4 (DMS4). Unlike other mutants defective in RdDM, dms4 mutants have a pleiotropic developmental phenotype. The DMS4 protein is similar to yeast IWR1 (interacts with RNA polymerase II), a conserved putative transcription factor that interacts with Pol II subunits. The DMS4 complementary DNA partly complements the K1 killer toxin hypersensitivity of a yeast iwr1 mutant, suggesting some functional conservation. In the transgenic system studied, mutations in DMS4 directly or indirectly affect Pol IV-dependent secondary short interfering RNAs, Pol V-mediated RdDM, Pol V-dependent synthesis of intergenic non-coding RNA and expression of many Pol II-driven genes. These data suggest that DMS4 might be a regulatory factor for several RNA polymerases, thus explaining its diverse roles in the plant.

  3. Direct evidence of an elongation factor-Tu/Ts·GTP·Aminoacyl-tRNA quaternary complex.

    PubMed

    Burnett, Benjamin J; Altman, Roger B; Ferguson, Angelica; Wasserman, Michael R; Zhou, Zhou; Blanchard, Scott C

    2014-08-22

    During protein synthesis, elongation factor-Tu (EF-Tu) bound to GTP chaperones the entry of aminoacyl-tRNA (aa-tRNA) into actively translating ribosomes. In so doing, EF-Tu increases the rate and fidelity of the translation mechanism. Recent evidence suggests that EF-Ts, the guanosine nucleotide exchange factor for EF-Tu, directly accelerates both the formation and dissociation of the EF-Tu-GTP-Phe-tRNA(Phe) ternary complex (Burnett, B. J., Altman, R. B., Ferrao, R., Alejo, J. L., Kaur, N., Kanji, J., and Blanchard, S. C. (2013) J. Biol. Chem. 288, 13917-13928). A central feature of this model is the existence of a quaternary complex of EF-Tu/Ts·GTP·aa-tRNA(aa). Here, through comparative investigations of phenylalanyl, methionyl, and arginyl ternary complexes, and the development of a strategy to monitor their formation and decay using fluorescence resonance energy transfer, we reveal the generality of this newly described EF-Ts function and the first direct evidence of the transient quaternary complex species. These findings suggest that EF-Ts may regulate ternary complex abundance in the cell through mechanisms that are distinct from its guanosine nucleotide exchange factor functions.

  4. Hemophilia as a defect of the tissue factor pathway of blood coagulation: Effect of factors VIII and IX on factor X activation in a continuous-flow reactor

    SciTech Connect

    Repke, D.; Gemmell, C.H.; Guha, A.; Turitto, V.T.; Nemerson, Y. ); Broze, G.J. Jr. )

    1990-10-01

    The effect of factors VIII and IX on the ability of the tissue factor-factor VIIa complex to activate factor X was studied in a continuous-flow tubular enzyme reactor. Tissue factor immobilized in a phospholipid bilayer on the inner surface of the tube was exposed to a perfusate containing factors VIIa, VIII, IX, and X flowing at a wall shear rate of 57, 300, or 1130 sec{sup {minus}1}. The addition of factors VIII and IX at their respective plasma concentrations resulted in a further 2{endash}-to 3{endash}fold increase. The direct activation of factor X by tissue factor-factor VIIa could be virtually eliminated by the lipoprotein-associated coagulation inhibitor. These results suggest that the tissue factor pathway, mediated through factors VIII and IX, produces significant levels of factor Xa even in the presence of an inhibitor of the tissue factor-factor VIIa complex; moreover, the activation is dependent on local shear conditions. These findings are consistent both with a model of blood coagulation in which initiation of the system results from tissue factor and with the bleeding observed in hemophilia.

  5. Rice xa13 recessive resistance to bacterial blight is defeated by induction of the disease susceptibility gene Os-11N3.

    PubMed

    Antony, Ginny; Zhou, Junhui; Huang, Sheng; Li, Ting; Liu, Bo; White, Frank; Yang, Bing

    2010-11-01

    The rice (Oryza sativa) gene xa13 is a recessive resistance allele of Os-8N3, a member of the NODULIN3 (N3) gene family, located on rice chromosome 8. Os-8N3 is a susceptibility (S) gene for Xanthomonas oryzae pv oryzae, the causal agent of bacterial blight, and the recessive allele is defeated by strains of the pathogen producing any one of the type III effectors AvrXa7, PthXo2, or PthXo3, which are all members of the transcription activator-like (TAL) effector family. Both AvrXa7 and PthXo3 induce the expression of a second member of the N3 gene family, here named Os-11N3. Insertional mutagenesis or RNA-mediated silencing of Os-11N3 resulted in plants with loss of susceptibility specifically to strains of X. oryzae pv oryzae dependent on AvrXa7 or PthXo3 for virulence. We further show that AvrXa7 drives expression of Os-11N3 and that AvrXa7 interacts and binds specifically to an effector binding element within the Os-11N3 promoter, lending support to the predictive models for TAL effector binding specificity. The result indicates that variations in the TAL effector repetitive domains are driven by selection to overcome both dominant and recessive forms of resistance to bacterial blight in rice. The finding that Os-8N3 and Os-11N3 encode closely related proteins also provides evidence that N3 proteins have a specific function in facilitating bacterial blight disease.

  6. A density gradient of basic fibroblast growth factor guides directional migration of vascular smooth muscle cells.

    PubMed

    Wu, Jindan; Mao, Zhengwei; Han, Lulu; Zhao, Yizhi; Xi, Jiabin; Gao, Changyou

    2014-05-01

    The migration of vascular smooth muscle cells (VSMCs) is an important process in many physiological events. It is of paramount importance to control the migration rate and direction of VSMCs by biomaterials. In this paper, a density gradient of basic fibroblast growth factor (bFGF) was fabricated using an injection method and the bio-conjugation between heparin and bFGF. The density of bFGF gradually increased with a slope of 17 ng/cm(2)/mm. Adhesion and migration of VSMCs were studied on the bFGF gradient. The VSMCs exhibited preferential orientation and an enhanced directional migration behavior on the gradient surface. Up to 70% cells migrated towards the region with a higher density of bFGF on the gradient. However, the bFGF gradient had no effect on the cell migration rate. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Discovery of directional and nondirectional pioneer transcription factors by modeling DNase profile magnitude and shape.

    PubMed

    Sherwood, Richard I; Hashimoto, Tatsunori; O'Donnell, Charles W; Lewis, Sophia; Barkal, Amira A; van Hoff, John Peter; Karun, Vivek; Jaakkola, Tommi; Gifford, David K

    2014-02-01

    We describe protein interaction quantitation (PIQ), a computational method for modeling the magnitude and shape of genome-wide DNase I hypersensitivity profiles to identify transcription factor (TF) binding sites. Through the use of machine-learning techniques, PIQ identified binding sites for >700 TFs from one DNase I hypersensitivity analysis followed by sequencing (DNase-seq) experiment with accuracy comparable to that of chromatin immunoprecipitation followed by sequencing (ChIP-seq). We applied PIQ to analyze DNase-seq data from mouse embryonic stem cells differentiating into prepancreatic and intestinal endoderm. We identified 120 and experimentally validated eight 'pioneer' TF families that dynamically open chromatin. Four pioneer TF families only opened chromatin in one direction from their motifs. Furthermore, we identified 'settler' TFs whose genomic binding is principally governed by proximity to open chromatin. Our results support a model of hierarchical TF binding in which directional and nondirectional pioneer activity shapes the chromatin landscape for population by settler TFs.

  8. Pathways to adult sexual revictimization: direct and indirect behavioral risk factors across the lifespan.

    PubMed

    Fargo, Jamison D

    2009-11-01

    The purpose of this study is to investigate direct and indirect social and behavioral risk factors for adult sexual revictimization. Participants include 147 adult, predominantly African American (88%) women, 59% of whom had a documented history of child sexual abuse. Participants are interviewed in adulthood about adolescent and adult sexual victimization as well as other background and lifestyle characteristics. Structural equation modeling indicates that the relationship between child and adolescent sexual victimization is indirect, mediated by adolescent risk-taking behavior. The relationship between adolescent and adult sexual victimization is also indirect, mediated by risky sexual behavior. The residual effects of early childhood family environment and childhood physical abuse also indirectly predict sexual revictimization. Results provide empirical support for the general supposition that the relationship between child and adult sexual victimization is complex and that many intermediary factors differentially affect risk for a heightened vulnerability to sexual revictimization.

  9. Low back pain in older adults: risk factors, management options and future directions.

    PubMed

    Wong, Arnold Yl; Karppinen, Jaro; Samartzis, Dino

    2017-01-01

    Low back pain (LBP) is one of the major disabling health conditions among older adults aged 60 years or older. While most causes of LBP among older adults are non-specific and self-limiting, seniors are prone to develop certain LBP pathologies and/or chronic LBP given their age-related physical and psychosocial changes. Unfortunately, no review has previously summarized/discussed various factors that may affect the effective LBP management among older adults. Accordingly, the objectives of the current narrative review were to comprehensively summarize common causes and risk factors (modifiable and non-modifiable) of developing severe/chronic LBP in older adults, to highlight specific issues in assessing and treating seniors with LBP, and to discuss future research directions. Existing evidence suggests that prevalence rates of severe and chronic LBP increase with older age. As compared to working-age adults, older adults are more likely to develop certain LBP pathologies (e.g., osteoporotic vertebral fractures, tumors, spinal infection, and lumbar spinal stenosis). Importantly, various age-related physical, psychological, and mental changes (e.g., spinal degeneration, comorbidities, physical inactivity, age-related changes in central pain processing, and dementia), as well as multiple risk factors (e.g., genetic, gender, and ethnicity), may affect the prognosis and management of LBP in older adults. Collectively, by understanding the impacts of various factors on the assessment and treatment of older adults with LBP, both clinicians and researchers can work toward the direction of more cost-effective and personalized LBP management for older people.

  10. Human directed aggression in Brazilian domestic cats: owner reported prevalence, contexts and risk factors.

    PubMed

    Ramos, Daniela; Mills, Daniel Simon

    2009-10-01

    Aggression by cats towards humans is a serious behavioural, welfare and public health problem, although owners may believe it is an inevitable part of cat ownership. There has been little scientific investigation of the risk factors associated with this problem. One hundred and seven owners in the Sao Paulo region of Brazil, took part in a survey aimed at investigating the perceived prevalence of the problem, defining the most common contexts of human directed aggression and identifying associated potential risk factors. Human directed aggression occurred in 49.5% of cats and was most commonly associated with situations involving petting and play, followed by protection of a resource, when startled, when observing an unfamiliar animal and least commonly when unfamiliar people were present. Pedigree status, neuter status, a history of early trauma, sensitivity to being stroked, the absence of other cats in the home, relationship with other animals, level of background activity at home, access to the outside and tendency to be alone (meaning tendency to staying far from the family members) were all associated with an increased risk in one or more context. However, sex, age, age when acquired, source of pet, attachment to a specific household member, type of domestic accommodation, relationship with another cat if present and contact with other animals did not appear to increase the risk. The results suggest sensitivity to being stroked and background levels of stress in the home are the most pervasive risk factors, and future research should aim to investigate these factors further. These data are of relevance when advising owners about the risk and development of this problem.

  11. Ethanol and Corticotropin Releasing Factor Receptor Modulation of Central Amygdala Neurocircuitry: an Update and Future Directions

    PubMed Central

    Silberman, Yuval; Winder, Danny G.

    2015-01-01

    The central amygdala is a critical brain region for many aspects of alcohol dependence. Much of the work examining the mechanisms by which the central amygdala mediates the development of alcohol dependence has focused on the interaction of acute and chronic ethanol with central amygdala corticotropin releasing factor signaling. This work has led to a great deal of success in furthering the general understanding of central amygdala neurocircuitry and its role in alcohol dependence. Much of this work has primarily focused on the hypothesis that ethanol utilizes endogenous corticotropin releasing factor signaling to upregulate inhibitory GABAergic transmission in the central amygdala. Work that is more recent suggests that corticotropin releasing factor also plays an important role in mediating anxiety-like behaviors via the enhancement of central amygdala glutamatergic transmission, implying that ethanol/corticotropin releasing factor interactions may modulate excitatory neurotransmission in this brain region. In addition, a number of studies utilizing optogenetic strategies or transgenic mouse lines have begun to examine specific central amygdala neurocircuit dynamics and neuronal subpopulations to better understand overall central amygdala neurocircuitry and the role of neuronal subtypes in mediating anxiety-like behaviors. This review will provide a brief update on this literature and describe some potential future directions that may be important for the development of better treatments for alcohol addiction. PMID:25716197

  12. Ethanol and corticotropin releasing factor receptor modulation of central amygdala neurocircuitry: An update and future directions.

    PubMed

    Silberman, Yuval; Winder, Danny G

    2015-05-01

    The central amygdala is a critical brain region for many aspects of alcohol dependence. Much of the work examining the mechanisms by which the central amygdala mediates the development of alcohol dependence has focused on the interaction of acute and chronic ethanol with central amygdala corticotropin releasing factor signaling. This work has led to a great deal of success in furthering the general understanding of central amygdala neurocircuitry and its role in alcohol dependence. Much of this work has primarily focused on the hypothesis that ethanol utilizes endogenous corticotropin releasing factor signaling to upregulate inhibitory GABAergic transmission in the central amygdala. Work that is more recent suggests that corticotropin releasing factor also plays an important role in mediating anxiety-like behaviors via the enhancement of central amygdala glutamatergic transmission, implying that ethanol/corticotropin releasing factor interactions may modulate excitatory neurotransmission in this brain region. In addition, a number of studies utilizing optogenetic strategies or transgenic mouse lines have begun to examine specific central amygdala neurocircuit dynamics and neuronal subpopulations to better understand overall central amygdala neurocircuitry and the role of neuronal subtypes in mediating anxiety-like behaviors. This review will provide a brief update on this literature and describe some potential future directions that may be important for the development of better treatments for alcohol addiction.

  13. Factors influencing implementation of medical directives by registered nurses: the experience of a large Ontario teaching hospital.

    PubMed

    Alvarado, Kim

    2007-01-01

    To understand factors that affect the implementation of medical directives by registered nurses in a large teaching hospital. Qualitative nested case study. A large multi-site teaching hospital that utilizes over 20 different medical directives was chosen as the setting for this case study. Three distinct medical directives within this setting were selected to obtain maximum variation in the number of individuals involved in a particular directive and type of clinical area. Between March and October 2005, 27 individuals concerned with clinical implementation of these medical directives were interviewed using a semi-structured interview schedule. The registrars of two regulatory bodies that oversee policies related to medical directives and a consultant with expertise in medical directives were also interviewed. Eleven documents related to the use of medical directives were identified using purposive document sampling methods and were included in the study. Implementation of medical directives is influenced by a variety of factors, including nurse confidence and willingness to assume responsibility, the amount of new learning needed to carry out the directive and additional paperwork required. Perceived usefulness of the medical directive, physician support of nurses' use of the directives and frequency of encounter with that type of patient were also important factors. The implementation of a medical directive is a complex process; directives are difficult to write well and often affect the scope of practice of other healthcare professionals. The amount of education and monitoring required to implement a directive needs careful consideration to ensure the appropriate resources are available to support implementation. Greater attention to the factors that facilitate implementation of medical directives is required in order to implement directives in an efficient and effective manner.

  14. Imitative and Direct Learning as Interacting Factors in Life History Evolution.

    PubMed

    Bullinaria, John A

    2017-01-01

    The idea that lifetime learning can have a significant effect on life history evolution has recently been explored using a series of artificial life simulations. These involved populations of competing individuals evolving by natural selection to learn to perform well on simplified abstract tasks, with the learning consisting of identifying regularities in their environment. In reality, there is more to learning than that type of direct individual experience, because it often includes a substantial degree of social learning that involves various forms of imitation of what other individuals have learned before them. This article rectifies that omission by incorporating memes and imitative learning into revised versions of the previous approach. To do this reliably requires formulating and testing a general framework for meme-based simulations that will enable more complete investigations of learning as a factor in any life history evolution scenarios. It does that by simulating imitative information transfer in terms of memes being passed between individuals, and developing a process for merging that information with the (possibly inconsistent) information acquired by direct experience, leading to a consistent overall body of learning. The proposed framework is tested on a range of learning variations and a representative set of life history factors to confirm the robustness of the approach. The simulations presented illustrate the types of interactions and tradeoffs that can emerge, and indicate the kinds of species-specific models that could be developed with this approach in the future.

  15. MicroRNA-218 inhibits melanogenesis by directly suppressing microphthalmia-associated transcription factor expression

    PubMed Central

    Guo, Jia; Zhang, Jin-Fang; Wang, Wei-Mao; Cheung, Florence Wing-ki; Lu, Ying-fei; Ng, Chi-fai; Kung, Hsiang-fu; Liu, Wing-keung

    2014-01-01

    The microphthalmia-associated transcription factor (MITF) is a pivotal regulator of melanogenic enzymes for melanogenesis, and its expression is modulated by many transcriptional factors at the transcriptional level or post-transcriptional level through microRNAs (miRNAs). Although several miRNAs modulate melanogenic activities, there is no evidence of their direct action on MITF expression. Out of eight miRNAs targeting the 3′-UTR of Mitf predicted by bioinformatic programs, our results show miR-218 to be a novel candidate for direct action on MITF expression. Ectopic miR-218 dramatically reduced MITF expression, suppressed tyrosinase activity, and induced depigmentation in murine immortalized melan-a melanocytes. MiR-218 also suppressed melanogenesis in human pigmented skin organotypic culture (OTC) through the repression of MITF. An inverse correlation between MITF and miR-218 expression was found in human primary skin melanocytes and melanoma cell lines. Taken together, our findings demonstrate a novel mechanism involving miR-218 in the regulation of the MITF pigmentary process and its potential application for skin whitening therapy. PMID:24824743

  16. Hypoxia-inducible factor directs POMC gene to mediate hypothalamic glucose sensing and energy balance regulation.

    PubMed

    Zhang, Hai; Zhang, Guo; Gonzalez, Frank J; Park, Sung-Min; Cai, Dongsheng

    2011-07-01

    Hypoxia-inducible factor (HIF) is a nuclear transcription factor that responds to environmental and pathological hypoxia to induce metabolic adaptation, vascular growth, and cell survival. Here we found that HIF subunits and HIF2α in particular were normally expressed in the mediobasal hypothalamus of mice. Hypothalamic HIF was up-regulated by glucose to mediate the feeding control of hypothalamic glucose sensing. Two underlying molecular pathways were identified, including suppression of PHDs by glucose metabolites to prevent HIF2α degradation and the recruitment of AMPK and mTOR/S6K to regulate HIF2α protein synthesis. HIF activation was found to directly control the transcription of POMC gene. Genetic approach was then employed to develop conditional knockout mice with HIF inhibition in POMC neurons, revealing that HIF loss-of-function in POMC neurons impaired hypothalamic glucose sensing and caused energy imbalance to promote obesity development. The metabolic effects of HIF in hypothalamic POMC neurons were independent of leptin signaling or pituitary ACTH pathway. Hypothalamic gene delivery of HIF counteracted overeating and obesity under conditions of nutritional excess. In conclusion, HIF controls hypothalamic POMC gene to direct the central nutrient sensing in regulation of energy and body weight balance.

  17. 78 FR 70209 - Airworthiness Directives; XtremeAir GmbH Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-25

    ...-047-AD; Amendment 39-17674; AD 2013-23-19] RIN 2120-AA64 Airworthiness Directives; XtremeAir GmbH.... SUMMARY: We are adopting a new airworthiness directive (AD) for XtremeAir GmbH Model XA42 airplanes. This... integrity of the airplane and could result in engine separation. We are issuing this AD to require actions...

  18. Directed evolution of brain-derived neurotrophic factor for improved folding and expression in Saccharomyces cerevisiae.

    PubMed

    Burns, Michael L; Malott, Thomas M; Metcalf, Kevin J; Hackel, Benjamin J; Chan, Jonah R; Shusta, Eric V

    2014-09-01

    Brain-derived neurotrophic factor (BDNF) plays an important role in nervous system function and has therapeutic potential. Microbial production of BDNF has resulted in a low-fidelity protein product, often in the form of large, insoluble aggregates incapable of binding to cognate TrkB or p75 receptors. In this study, employing Saccharomyces cerevisiae display and secretion systems, it was found that BDNF was poorly expressed and partially inactive on the yeast surface and that BDNF was secreted at low levels in the form of disulfide-bonded aggregates. Thus, for the purpose of increasing the compatibility of yeast as an expression host for BDNF, directed-evolution approaches were employed to improve BDNF folding and expression levels. Yeast surface display was combined with two rounds of directed evolution employing random mutagenesis and shuffling to identify BDNF mutants that had 5-fold improvements in expression, 4-fold increases in specific TrkB binding activity, and restored p75 binding activity, both as displayed proteins and as secreted proteins. Secreted BDNF mutants were found largely in the form of soluble homodimers that could stimulate TrkB phosphorylation in transfected PC12 cells. Site-directed mutagenesis studies indicated that a particularly important mutational class involved the introduction of cysteines proximal to the native cysteines that participate in the BDNF cysteine knot architecture. Taken together, these findings show that yeast is now a viable alternative for both the production and the engineering of BDNF.

  19. Betrixaban compared with warfarin in patients with atrial fibrillation: results of a phase 2, randomized, dose-ranging study (Explore-Xa)

    PubMed Central

    Connolly, Stuart J.; Eikelboom, John; Dorian, Paul; Hohnloser, Stefan H.; Gretler, Daniel D.; Sinha, Uma; Ezekowitz, Michael D.

    2013-01-01

    Aims Patients with atrial fibrillation (AF) are at increased risk of stroke. Betrixaban is a novel oral factor Xa inhibitor administered once daily, mostly excreted unchanged in the bile and with low (17%) renal excretion. Methods and results Patients with AF and more than one risk factor for stroke were randomized to one of three blinded doses of betrixaban (40, 60, or 80 mg once daily) or unblinded warfarin, adjusted to an international normalized ratio of 2.0–3.0. The primary outcome was major or clinically relevant non-major bleeding. The mean follow-up was 147 days. Among 508 patients randomized, the mean CHADS2 score was 2.2; 87% of patients had previously received vitamin K antagonist therapy. The time in therapeutic range on warfarin was 63.4%. There were one, five, five, and seven patients with a primary outcome on betrixaban 40, 60, 80 mg daily, or warfarin, respectively. The rate of the primary outcome was lowest on betrixaban 40 mg (hazard ratio compared with warfarin = 0.14, exact stratified log-rank P-value 0.04, unadjusted for multiple testing). Rates of the primary outcome with betrixaban 60 or 80 mg were more similar to those of wafarin. Two ischaemic strokes occurred, one each on betrixaban 60 and 80 mg daily. There were two vascular deaths, one each on betrixaban 40 mg and warfarin. Betrixaban was associated with higher rates of diarrhoea than warfarin. Conclusion Betrixaban was well tolerated and had similar or lower rates of bleeding compared with well-controlled warfarin in patients with AF at risk for stroke. PMID:23487517

  20. Youth anxiety and parent factors over time: directionality of change among youth treated for anxiety.

    PubMed

    Settipani, Cara A; O'Neil, Kelly A; Podell, Jennifer L; Beidas, Rinad S; Kendall, Philip C

    2013-01-01

    The relationship between improvements in child anxiety and changes in parent factors (e.g., parental anxiety, parenting behaviors) is poorly understood. The present study investigated the directionality of change for child anxiety and parent factors among youth treated for anxiety disorders. Structural equation modeling examined these relationships pre- to posttreatment and at 1-year follow-up for 111 youth aged 7 to 14 (57% male, 84% Caucasian). Child anxiety was measured using the Anxiety Disorders Interview Schedule for Children and the Child Behavior Checklist. The State-Trait Anxiety Inventory, Children's Report of Parental Behavior Inventory, and Family Assessment Device were used to measure maternal anxiety, psychological control, behavior control, and family affective involvement. Findings suggest that decreases in mother-reported child anxiety led to decreases in maternal anxiety. Decreases in maternal psychological control and family affective involvement preceded decreases in clinician-rated child anxiety. Youth who showed the most reductions in anxiety over the course of treatment were those who tended to have lower family affective involvement, behavior control, and maternal anxiety at pretreatment. Stability of the parent factors and child anxiety over time suggest that stability was greater for behavior control and maternal anxiety relative to affective involvement and psychological control. The findings are consistent with previous research indicating the importance of these parent factors as they relate to anxiety in youth. Furthermore, results indicate that changes in child anxiety may precede changes in parent factors and suggest that parental psychological control and affective involvement are important treatment targets for youth with anxiety disorders.

  1. Biomechanical factors associated with time to complete a change of direction cutting maneuver.

    PubMed

    Marshall, Brendan M; Franklyn-Miller, Andrew D; King, Enda A; Moran, Kieran A; Strike, Siobhán C; Falvey, Éanna C

    2014-10-01

    Cutting ability is an important aspect of many team sports, however, the biomechanical determinants of cutting performance are not well understood. This study aimed to address this issue by identifying the kinetic and kinematic factors correlated with the time to complete a cutting maneuver. In addition, an analysis of the test-retest reliability of all biomechanical measures was performed. Fifteen (n = 15) elite multidirectional sports players (Gaelic hurling) were recruited, and a 3-dimensional motion capture analysis of a 75° cut was undertaken. The factors associated with cutting time were determined using bivariate Pearson's correlations. Intraclass correlation coefficients (ICCs) were used to examine the test-retest reliability of biomechanical measures. Five biomechanical factors were associated with cutting time (2.28 ± 0.11 seconds): peak ankle power (r = 0.77), peak ankle plantar flexor moment (r = 0.65), range of pelvis lateral tilt (r = -0.54), maximum thorax lateral rotation angle (r = 0.51), and total ground contact time (r = -0.48). Intraclass correlation coefficient scores for these 5 factors, and indeed for the majority of the other biomechanical measures, ranged from good to excellent (ICC >0.60). Explosive force production about the ankle, pelvic control during single-limb support, and torso rotation toward the desired direction of travel were all key factors associated with cutting time. These findings should assist in the development of more effective training programs aimed at improving similar cutting performances. In addition, test-retest reliability scores were generally strong, therefore, motion capture techniques seem well placed to further investigate the determinants of cutting ability.

  2. Direct CP Violation, Branching Ratios and Form Factors B --> pi, B --> K in B decays

    SciTech Connect

    O. Leitner; X.-H. Guo; A.W. Thomas

    2004-11-01

    The B {yields} {pi} and B {yields} K transitions involved in hadronic B decays are investigated in a phenomenological way through the framework of QCD factorization. By comparing our results with experimental branching ratios from the BELLE, BABAR and CLEO collaborations for all the B decays including either a pion or a kaon, we propose boundaries for the transition form factors B {yields} {pi} and B {yields} K depending on the CKM matrix element parameters {rho} and {eta}. From this analysis, the form factors required to reproduce the experimental data for branching ratios are F{sup B {yields} {pi}} = 0.31 {+-} 0.12 and F{sup B {yields} K} = 0.37 {+-} 0.13. We calculate the direct CP violating asymmetry parameter, a{sub CP}, for B {yields} {pi}{sup +}{pi}{sup -}{pi} and B {yields} {pi}{sup +}{pi}{sup -} K decays, in the case where {rho} - {omega} mixing effects are taken into account. Based on these results, we find that the direct CP asymmetry for B{sup -} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup -}, {bar B}{sup 0} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0}, B{sup -} {yields} {pi}{sup +}{pi}{sup -}K{sup -}, and {bar B}{sup 0} {yields} {pi}{sup +}{pi}{sup -} {bar K}{sup 0}, reaches its maximum when the invariant mass {pi}{sup +}{pi}{sup -} is in the vicinity of the {omega} meson mass. The inclusion of {rho} - {omega} mixing provides an opportunity to erase, without ambiguity, the phase uncertainty mod{pi} in the determination of th CKM angles {alpha} in case of b {yields} u and {gamma} in case of b {yields} s.

  3. Direct measurement of electron beam quality conversion factors using water calorimetry.

    PubMed

    Renaud, James; Sarfehnia, Arman; Marchant, Kristin; McEwen, Malcolm; Ross, Carl; Seuntjens, Jan

    2015-11-01

    In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9-20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%-0.40%) and its influence on the perturbation correction (Type B, 0.10%-0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, kecal, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM's TG-51 protocol. General agreement between the relative

  4. Direct measurement of electron beam quality conversion factors using water calorimetry

    SciTech Connect

    Renaud, James Seuntjens, Jan; Sarfehnia, Arman; Marchant, Kristin; McEwen, Malcolm; Ross, Carl

    2015-11-15

    Purpose: In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. Methods: A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. Results: The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9–20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%–0.40%) and its influence on the perturbation correction (Type B, 0.10%–0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, k{sub ecal}, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM’s TG-51 protocol

  5. Proportion of beneficiaries and factors affecting Janani Suraksha Yojana direct cash transfer scheme in Puducherry, India

    PubMed Central

    Rajarajan, K.; Kumar, S. Ganesh; Kar, Sitanshu Sekhar

    2016-01-01

    Introduction: Janani Suraksha Yojana (JSY) direct benefit transfer scheme was launched in the year 2013 in India and there is a paucity of information affecting it. The study aimed to assess the proportion of eligible beneficiaries utilizing JSY direct cash benefit transfer in Puducherry and to identify its barriers and facilitating factors. Methods: This cross sectional study was conducted from January to March 2015 among 152 eligible JSY beneficiaries residing in rural and urban field practice areas of a tertiary care institution in Puducherry, India. Data were collected using a pretested semi structured questionnaire and presented as proportion or percentages. Results: About 144 beneficiaries participated in the study with a response rate of 94.7%. About 46% (66) of them availed cash transfer benefit. The mean time of receiving the benefit is 95.8 days (interquartile range 60–120 days). Among those who have not received (78), about 49 (62.8%) had not applied and 29 (37.18%) filled applications were rejected due to various reasons. About 77.1% (111) of beneficiaries were informed about JSY scheme through health workers. About 52.1% (75/144) still preferred direct bank transfer through the bank. The reasons for not availing benefits includes not having a bank account (24.3%), followed by not having Aadhaar number (9.7%), 11.8% had no ration card, and 13.8% stayed in their mother house. Conclusion: Majority of the beneficiaries did not receive direct cash transfer benefits in urban area than rural area and there is a need to simplify the procedures to improve the uptake of services to this group. PMID:28348997

  6. Proportion of beneficiaries and factors affecting Janani Suraksha Yojana direct cash transfer scheme in Puducherry, India.

    PubMed

    Rajarajan, K; Kumar, S Ganesh; Kar, Sitanshu Sekhar

    2016-01-01

    Janani Suraksha Yojana (JSY) direct benefit transfer scheme was launched in the year 2013 in India and there is a paucity of information affecting it. The study aimed to assess the proportion of eligible beneficiaries utilizing JSY direct cash benefit transfer in Puducherry and to identify its barriers and facilitating factors. This cross sectional study was conducted from January to March 2015 among 152 eligible JSY beneficiaries residing in rural and urban field practice areas of a tertiary care institution in Puducherry, India. Data were collected using a pretested semi structured questionnaire and presented as proportion or percentages. About 144 beneficiaries participated in the study with a response rate of 94.7%. About 46% (66) of them availed cash transfer benefit. The mean time of receiving the benefit is 95.8 days (interquartile range 60-120 days). Among those who have not received (78), about 49 (62.8%) had not applied and 29 (37.18%) filled applications were rejected due to various reasons. About 77.1% (111) of beneficiaries were informed about JSY scheme through health workers. About 52.1% (75/144) still preferred direct bank transfer through the bank. The reasons for not availing benefits includes not having a bank account (24.3%), followed by not having Aadhaar number (9.7%), 11.8% had no ration card, and 13.8% stayed in their mother house. Majority of the beneficiaries did not receive direct cash transfer benefits in urban area than rural area and there is a need to simplify the procedures to improve the uptake of services to this group.

  7. Contributing Factors to Change-of-Direction Ability in Professional Rugby League Players.

    PubMed

    Delaney, Jace A; Scott, Tannath J; Ballard, David A; Duthie, Grant M; Hickmans, Jeremy A; Lockie, Robert G; Dascombe, Ben J

    2015-10-01

    Rugby league is an intermittent team sport in which players are regularly required to accelerate, decelerate, and change direction rapidly. This study aimed to determine the contributing factors to change-of-direction (COD) ability in professional rugby league players and to validate the physical and physiological components of a previously proposed COD ability predictor model. Thirty-one male professional rugby league players (age: 24.3 ± 4.4 years; height: 1.83 ± 0.06 m; body mass: 98.1 ± 9.8 kg) were assessed for anthropometry, linear speed, various leg muscle qualities, and COD ability. Change-of-direction ability was assessed for both the dominant (D) and nondominant (ND) legs using the 505 test. Stepwise multiple regression analyses determined the combined effect of the physical and physiological variables on COD ability. Maximal linear speed (SpMax) and relative squat strength (squat:BM) explained 61% of the variance in 505-D performance, whereas measures of mass, unilateral, and bilateral power contributed 67% to 505-ND performance. These results suggest that the 505-ND task was heavily dependent on relative strength and power, whereas the 505-D task was best predicted by linear sprint speed. Second, the physical component of the COD predictor model demonstrated poor correlations (r = -0.1 to -0.5) between absolute strength and power measures and COD ability. When made relative to body mass, strength and power measures and COD ability shared stronger relationships (r = -0.3 to -0.7). Change-of-direction ability in professional rugby league players would be best improved through increases in an athlete's strength and power while maintaining lean muscle mass.

  8. Determining the direction of causality between psychological factors and aircraft noise annoyance.

    PubMed

    Kroesen, Maarten; Molin, Eric J E; van Wee, Bert

    2010-01-01

    In this paper, an attempt is made to establish the direction of causality between a range of psychological factors and aircraft noise annoyance. For this purpose, a panel model was estimated within a structural equation modeling approach. Data were gathered from two surveys conducted in April 2006 and April 2008, respectively, among the same residents living within the 45 Level day-evening-night contour of Amsterdam Airport Schiphol, the largest airport in the Netherlands (n=250). A surprising result is that none of the paths from the psychological factors to aircraft noise annoyance were found to be significant. Yet 2 effects were significant the other way around: (1) from 'aircraft noise annoyance' to 'concern about the negative health effects of noise' and (2) from 'aircraft noise annoyance' to 'belief that noise can be prevented.' Hence aircraft noise annoyance measured at time 1 contained information that can effectively explain changes in these 2 variables at time 2, while controlling for their previous values. Secondary results show that (1) aircraft noise annoyance is very stable through time and (2) that changes in aircraft noise annoyance and the identified psychological factors are correlated.

  9. Literacy and race as risk factors for low rates of advance directives in older adults.

    PubMed

    Waite, Katherine R; Federman, Alex D; McCarthy, Danielle M; Sudore, Rebecca; Curtis, Laura M; Baker, David W; Wilson, Elizabeth A H; Hasnain-Wynia, Romana; Wolf, Michael S; Paasche-Orlow, Michael K

    2013-03-01

    To examine the effect of the relationship between literacy and other individual-level factors on having an advance directive (AD). Face-to-face structured interview. Participants were recruited from an academic general internal medicine clinic and one of four federally qualified health centers in Chicago. Seven hundred eighty-four adults aged 55 to 74. Assessment of participant literacy, sociodemographic factors, and having an AD for medical care. One-eighth (12.4%) of participants with low literacy, 26.6% of those with marginal literacy, and 49.5% of those with adequate literacy reported having an AD (P < .001). In multivariable analyses, literacy and race were independently associated with less likelihood of having an AD. Specifically, participants with limited literacy (risk ratio (RR) = 0.45, 95% confidence interval (CI) = 0.22-0.95) and African Americans (RR = 0.64, 95% CI = 0.47-0.88) were less likely to have an AD. Exploratory analyses showed that there was not a significant interaction between the effect of literacy and race. Limited literacy and African-American race were significant risk factors for not having an AD in this cohort of older adults. Literacy and race probably represent two separate but important causal pathways that need to be understood to improve how the healthcare system ascertains and protects individuals' advance care preferences. © 2013, Copyright the Authors Journal compilation © 2013, The American Geriatrics Society.

  10. Direct interaction of avermectin with epidermal growth factor receptor mediates the penetration resistance in Drosophila larvae

    PubMed Central

    Chen, Li-Ping; Wang, Pan; Sun, Ying-Jian; Wu, Yi-Jun

    2016-01-01

    With the widespread use of avermectins (AVMs) for managing parasitic and agricultural pests, the resistance of worms and insects to AVMs has emerged as a serious threat to human health and agriculture worldwide. The reduced penetration of AVMs is one of the main reasons for the development of the resistance to the chemicals. However, the detailed molecular mechanisms remain elusive. Here, we use the larvae of Drosophila melanogaster as the model organism to explore the molecular mechanisms underlying the development of penetration resistance to AVMs. We clearly show that the chitin layer is thickened and the efflux transporter P-glycoprotein (P-gp) is overexpressed in the AVM-resistant larvae epidermis. We reveal that the activation of the transcription factor Relish by the over-activated epidermal growth factor receptor (EGFR)/AKT/ERK pathway induces the overexpression of the chitin synthases DmeCHS1/2 and P-gp in the resistant larvae. Interestingly, we discover for the first time, to the best of our knowledge, that AVM directly interacts with EGFR and leads to the activation of the EGFR/AKT/ERK pathway, which activates the transcription factor Relish and induces the overexpression of DmeCHS1/2 and P-gp. These findings provide new insights into the molecular mechanisms underlying the development of penetration resistance to drugs. PMID:27249340

  11. Variations in vertebral body dimensions in women measured by 3D-XA: a longitudinal in vivo study.

    PubMed

    Kolta, S; Kerkeni, S; Travert, C; Skalli, W; Eastell, R; Glüer, C C; Roux, C

    2012-03-01

    Bone size and shape play an important role in bone strength, as shown by biomechanical testing and clinical studies. Vertebral body dimensions determine vertebral body strength even after adjustment for bone mineral density. We have recently proposed an in vivo method for 3D reconstruction of vertebral bodies using the whole spine imaging on a standard DXA device (3D-XA). The aim of our study was to measure in vivo vertebral body dimension changes by 3D-XA in women over a 6 year period. A total of 174 women were included in this study. They were divided into 3 groups: premenopausal (20-40 years; N=53), postmenopausal women (55-60 years; N=65) and elderly women (70-80 years; N=56). Thoracic and lumbar spine (T4-L4) were reconstructed using the 3D-XA method at baseline and 6 years later. Biochemical markers of bone remodeling were measured at baseline. In premenopausal women, there was an increase in minimal cross-sectional area (minCSA), vertebral body volume as well as end plate width of the lumbar vertebrae, without statistically significant change of these parameters at the thoracic spine; there was no change in anterior heights. In postmenopausal women, there was a decrease in vertebral body anterior height and depth, driven by results in the elderly group at both the thoracic and lumbar spine. Vertebral body width decreased at the thoracic spine but increased at the lumbar spine. MinCSA and volume decreased at the thoracic spine, in contrast with an increase of these 2 parameters at the lumbar spine in early postmenopausal women (55-60 years). In elderly women (70-80 years), the change in minCSA and volume of the lumbar spine was not statistically significant over 6 years. In postmenopausal women, there was no correlation between changes in vertebral dimensions and baseline biochemical markers of bone remodeling except for NTX/Cr and anterior height decrease. Our study confirms that an increase in geometric dimensions of lumbar vertebrae occurs through adult

  12. Transgenic expression of the rice Xa21 pattern recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum

    PubMed Central

    Tripathi, Jaindra Nath; Lorenzen, Jim; Bahar, Ofir; Ronald, Pamela; Tripathi, Leena

    2014-01-01

    Summary Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, bio-control agents or resistant cultivars available to control BXW. Here we take advantage of the robust resistance conferred by the rice pattern recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21 mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar ‘Gonja manjaya’ (AAB) using a rapid bioassay and 12 transgenic plants in the glass house for resistance against Xcm. About fifty percent of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the non-transgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa. PMID:24612254

  13. Analysis of nucleotide diversity among alleles of the major bacterial blight resistance gene Xa27 in cultivars of rice (Oryza sativa) and its wild relatives.

    PubMed

    Bimolata, Waikhom; Kumar, Anirudh; Sundaram, Raman Meenakshi; Laha, Gouri Shankar; Qureshi, Insaf Ahmed; Reddy, Gajjala Ashok; Ghazi, Irfan Ahmad

    2013-08-01

    Xa27 is one of the important R-genes, effective against bacterial blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Using natural population of Oryza, we analyzed the sequence variation in the functionally important domains of Xa27 across the Oryza species. DNA sequences of Xa27 alleles from 27 rice accessions revealed higher nucleotide diversity among the reported R-genes of rice. Sequence polymorphism analysis revealed synonymous and non-synonymous mutations in addition to a number of InDels in non-coding regions of the gene. High sequence variation was observed in the promoter region including the 5'UTR with 'π' value 0.00916 and 'θ w ' = 0.01785. Comparative analysis of the identified Xa27 alleles with that of IRBB27 and IR24 indicated the operation of both positive selection (Ka/Ks > 1) and neutral selection (Ka/Ks ≈ 0). The genetic distances of alleles of the gene from Oryza nivara were nearer to IRBB27 as compared to IR24. We also found the presence of conserved and null UPT (upregulated by transcriptional activator) box in the isolated alleles. Considerable amino acid polymorphism was localized in the trans-membrane domain for which the functional significance is yet to be elucidated. However, the absence of functional UPT box in all the alleles except IRBB27 suggests the maintenance of single resistant allele throughout the natural population.

  14. Identifying direct targets of transcription factor Rfx2 that coordinate ciliogenesis and cell movement

    PubMed Central

    Kwon, Taejoon; Chung, Mei-I; Gupta, Rakhi; Baker, Julie C.; Wallingford, John B.; Marcotte, Edward M.

    2014-01-01

    Recently, using the frog Xenopus laevis as a model system, we showed that the transcription factor Rfx2 coordinates many genes involved in ciliogenesis and cell movement in multiciliated cells (Chung et al., 2014). To our knowledge, it was the first paper to utilize the genomic resources, including genome sequences and interim gene annotations, from the ongoing X. laevis genome project. For researchers who are interested in the application of genomics and systems biology approaches in Xenopus studies, here we provide additional details about our dataset (NCBI GEO accession number GSE50593) and describe how we analyzed RNA-seq and ChIP-seq data to identify direct targets of Rfx2. PMID:25419512

  15. Prospective Evaluation of Weight-Based Prophylactic Enoxaparin Dosing in Critically Ill Trauma Patients: Adequacy of AntiXa Levels Is Improved.

    PubMed

    Nunez, Jade M; Becher, Robert D; Rebo, Gerald J; Farrah, Jason P; Borgerding, Erika M; Stirparo, Joseph J; Lauer, Cynthia; Kilgo, Patrick; Miller, Preston R

    2015-06-01

    Venous thromboembolism (VTE) is a leading cause of death in multisystem trauma patients; the importance of VTE prevention is well recognized. Presently, standard dose enoxaparin (30 mg BID) is used as chemical prophylaxis, regardless of weight or physiologic status. However, evidence suggests decreased bioavailability of enoxaparin in critically ill patients. Therefore, we hypothesized that a weight-based enoxaparin dosing regimen would provide more adequate prophylaxis (as indicated by antifactor Xa levels) for patients in our trauma intensive care unit (TICU).These data were prospectively collected in TICU patients admitted over a 5-month period given twice daily 0.6 mg/kg enoxaparin (actual body weight). Patients were compared with a historical cohort receiving standard dosing. Anti-Xa levels were collected at 11.5 hours (trough, goal ≥ 0.1 IU/mL) after each evening administration. Patient demographics, admission weight, dose, and daily anti-Xa levels were recorded. Patients with renal insufficiency or brain, spine, or spinal cord injury were excluded. Data were collected from 26 patients in the standard-dose group and 37 in the weight-based group. Sixty-four trough anti-Xa measurements were taken in the standard dose group and 74 collected in the weight-based group. Evaluating only levels measured after the third dose, the change in dosing of enoxaparin from 30 to 0.6 mg/kg resulted in an increased percentage of patients with goal antifactor Xa levels from 8 per cent to 61 per cent (P < 0.0001). Examining all troughs, the change in dose resulted in an increase in patients with a goal anti-Xa level from 19 to 59 per cent (P < 0.0001). Weight-based dosing of enoxaparin in trauma ICU patients yields superior results with respect to adequate anti-Xa levels when compared with standard dosing. These findings suggest that weight-based dosing may provide superior VTE prophylaxis in TICU patients. Evaluation of the effects of this dosing paradigm on actual VTE rate is

  16. Impact damage resistance of carbon/epoxy composite tubes for the DC-XA liquid hydrogen feedline

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    1995-01-01

    Low-velocity impacts were inflicted upon two elbow sections of carbon/epoxy feedline that are to be a part of the Delta Clipper-XA flight vehicle. A soap-based liquid leak detector solution was used to inspect the impact sites for leaks of pressurized gas that was pumped into the tube. Visual surface damage was noted and recorded for each impact site. After impact testing of each of the two sections of tubes was completed, the damage zones were disected from the tube and cross sectioned through the impact site. These specimens were polished after potting them in epoxy and were examined for microcracking using a fluorescent dye penetrant technique. The results showed that nonvisible damage could cause microcracking, thereby resulting in leaks through the tube wall.

  17. Two transcription factors can direct three photoreceptor outcomes from rod precursor cells in mouse retinal development

    PubMed Central

    Ng, Lily; Lu, Ailing; Swaroop, Alok; Sharlin, David; Swaroop, Anand; Forrest, Douglas

    2011-01-01

    The typical mammalian visual system is based upon three photoreceptor types: rods for dim light vision and two types of cones (M and S) for color vision in daylight. However, the process that generates photoreceptor diversity and the cell type in which diversity arises remain unclear. Mice deleted for thyroid hormone receptor ®2 (TR®2) and neural retina leucine zipper factor (NRL) lack M cones and rods, respectively, but gain S cones. We therefore tested the hypothesis that NRL and TR®2 direct a common precursor to a rod, M cone or S cone outcome using Nrlb2/b2 “knock-in” mice that express TR®2 instead of NRL from the endogenous Nrl gene. Nrlb2/b2 mice lacked rods and produced excess M cones in contrast to the excess S cones in Nrl−/− mice. Notably, the presence of both factors yielded rods in Nrl+/b2 mice. The results demonstrate innate plasticity in post-mitotic rod precursors that allows these cells to form three functional photoreceptor types in response to NRL or TRβ2. We also detected precursor cells in normal embryonic retina that transiently co-expressed Nrl and TRβ2, suggesting that some precursors may originate in a plastic state. The plasticity of the precursors revealed in Nrlb2/b2 mice suggests that a two-step transcriptional switch can direct three photoreceptor fates: first, rod versus cone identity dictated by NRL and secondly, if NRL fails to act, M versus S cone identity dictated by TR®2. PMID:21813673

  18. Two transcription factors can direct three photoreceptor outcomes from rod precursor cells in mouse retinal development.

    PubMed

    Ng, Lily; Lu, Ailing; Swaroop, Alok; Sharlin, David S; Swaroop, Anand; Forrest, Douglas

    2011-08-03

    The typical mammalian visual system is based upon three photoreceptor types: rods for dim light vision and two types of cones (M and S) for color vision in daylight. However, the process that generates photoreceptor diversity and the cell type in which diversity arises remain unclear. Mice deleted for thyroid hormone receptor β2 (TRβ2) and neural retina leucine zipper factor (NRL) lack M cones and rods, respectively, but gain S cones. We therefore tested the hypothesis that NRL and TRβ2 direct a common precursor to a rod, M cone, or S cone outcome using Nrl(b2/b2) "knock-in" mice that express TRβ2 instead of NRL from the endogenous Nrl gene. Nrl(b2/b2) mice lacked rods and produced excess M cones in contrast to the excess S cones in Nrl(-/-) mice. Notably, the presence of both factors yielded rods in Nrl(+/b2) mice. The results demonstrate innate plasticity in postmitotic rod precursors that allows these cells to form three functional photoreceptor types in response to NRL or TRβ2. We also detected precursor cells in normal embryonic retina that transiently coexpressed Nrl and TRβ2, suggesting that some precursors may originate in a plastic state. The plasticity of the precursors revealed in Nrl(b2/b2) mice suggests that a two-step transcriptional switch can direct three photoreceptor fates: first, rod versus cone identity dictated by NRL, and second, if NRL fails to act, M versus S cone identity dictated by TRβ2.

  19. Coagulation factor X inhibitor from hundred-pace snake (Deinagkistrodon acutus) venom.

    PubMed

    Cox, A C

    1993-11-01

    Deinagkistrodon acutus venom contains a collection of anticoagulant proteins that has been reported to prevent prothrombinase assembly (Teng and Seegers, 1981, Thromb. Res. 23, 255). A partial sequence indicates that these proteins are related to the functionally equivalent protein in Trimeresurus flavoviridis (Atoda et al., 1991, J. Biochem. 106, 808). Inhibition of prothrombinase, the complex of Factors Xa and Va combined with phospholipids, is expressed in bovine, human, and rat plasmas as indicated by an assay dependent on only prothrombinase activity. The concentration dependence of inhibition of prothrombin conversion by different combinations of the components of bovine prothrombinase under the same conditions yielded estimates of apparent dissociation constants of 104 nM and 2 nM for complexes of the inhibitor with Factor Xa and with Factors Xa and Va, respectively. Because this inhibitor does not prevent Factor Xa alone from converting prothrombin, but blocks the other combinations, we conclude the inhibitor prevents the complex of Factors Xa and Va from binding to phospholipid surfaces and to prothrombin. The inhibitor also blocks the activation of Factor X by Factor VIIa and thromboplastin as well. However, the inhibitor has no effect on thrombin-induced clotting or fibrinolysis induced by either plasminogen activator or streptokinase. Therefore, this inhibitor has several properties required of an anticoagulant, therapeutic agent.

  20. Direct Reprogramming of Mouse and Human Fibroblasts into Multipotent Neural Stem Cells with a Single Factor

    PubMed Central

    Ring, Karen L.; Tong, Leslie M.; Balestra, Maureen E.; Javier, Robyn; Andrews-Zwilling, Yaisa; Li, Gang; Walker, David; Zhang, William R.; Kreitzer, Anatol C.; Huang, Yadong

    2012-01-01

    SUMMARY The generation of induced pluripotent stem (iPS) cells and induced neuronal (iN) cells from somatic cells provides new avenues for basic research and potential transplantation therapies for neurological diseases. However, clinical applications must consider the risk of tumor formation by iPS cells and the inability of iN cells to self-renew in culture. Here we report the generation of induced neural stem cells (iNSCs) from mouse and human fibroblasts by direct reprogramming with a single factor, Sox2. iNSCs express NSC markers and resemble wild-type NSCs in their morphology, self-renewal, ability to form neurospheres, and gene expression profiles. Cloned iNSCs differentiate into several types of mature neurons, as well as astrocytes and oligodendrocytes, indicating multipotency. Implanted iNSCs can survive and integrate in mouse brains and, unlike iPS cell-derived NSCs, do not generate tumors. Thus, self-renewable and multipotent iNSCs without tumorigenic potential can be generated directly from fibroblasts by reprogramming. PMID:22683203

  1. Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

    SciTech Connect

    Kumar, Nallani Vijay; Yang, Jianbo; Pillai, Jitesh K.; Rawat, Swati; Solano, Carlos; Kumar, Abhay; Grøtli, Morten; Stemmler, Timothy L.; Rosen, Barry P.; Tamás, Markus J.

    2015-12-28

    The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeastSaccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)]in vitroandin vivoand that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.

  2. PPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3

    DOE PAGES

    Ni, Weimin; Xu, Shou-Ling; González-Grandío, Eduardo; ...

    2017-05-11

    Upon light-induced nuclear translocation, phytochrome (phy) sensory photoreceptors interact with, and induce rapid phosphorylation and consequent ubiquitin-mediated degradation of, transcription factors, called PIFs, thereby regulating target gene expression and plant development. Nevertheless, the biochemical mechanism of phy-induced PIF phosphorylation has remained ill-defined. Here in this paper we identify a family of nuclear protein kinases, designated Photoregulatory Protein Kinases (PPK1–4; formerly called MUT9-Like Kinases (MLKs)), that interact with PIF3 and phyB in a light-induced manner in vivo. Genetic analyses demonstrate that the PPKs are collectively necessary for the normal light-induced phosphorylation and degradation of PIF3. PPK1 directly phosphorylates PIF3 in vitro,more » with a phosphosite pattern that strongly mimics the light-induced pattern in vivo. These data establish that the PPKs are directly involved in catalysing the photoactivated-phy-induced phosphorylation of PIF3 in vivo, and thereby are critical components of a transcriptionally centred signalling hub that pleiotropically regulates plant growth and development in response to multiple signalling pathways.« less

  3. Hemispherical directional reflectance factor using UAV and a hyperspectral camera, validation and crop field test

    NASA Astrophysics Data System (ADS)

    Hakala, T.; Honkavaara, E.; Markelin, L.

    2014-10-01

    Small unmanned aerial vehicle (UAV) and a prototype hyperspectral imaging camera (HSI) was used to measure the hemispherical directional reflectance factor (HDRF) of a test field with known light scattering properties. The HSI acquires a burst of 24 images within two seconds and all of these images are acquired with different spectral content. By using the autopilot of the UAV, the flight can be preplanned so that the target area is optimally covered with overlapping images from multiple view angles. Structure from motion (SFM) algorithm is used to accurately determine the view angles for each image. The HDRF is calculated for each ground pixel by determining view directions from all of the images for that particular pixel. The pixel intensity values are then processed to reflectance by using a reference panel, which has been measured in laboratory with Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO). The UAV flight was performed over a test field with different gravel targets. The targets have known HDRF and this allows us to validate the UAV results. Another test was performed over a crop field to display the potential of this method for crop monitoring.

  4. Direct phase-sensitive identification of a d-form factor density wave in underdoped cuprates

    PubMed Central

    Fujita, Kazuhiro; Hamidian, Mohammad H.; Edkins, Stephen D.; Kim, Chung Koo; Kohsaka, Yuhki; Azuma, Masaki; Takano, Mikio; Takagi, Hidenori; Eisaki, Hiroshi; Uchida, Shin-ichi; Allais, Andrea; Lawler, Michael J.; Kim, Eun-Ah; Sachdev, Subir; Davis, J. C. Séamus

    2014-01-01

    The identity of the fundamental broken symmetry (if any) in the underdoped cuprates is unresolved. However, evidence has been accumulating that this state may be an unconventional density wave. Here we carry out site-specific measurements within each CuO2 unit cell, segregating the results into three separate electronic structure images containing only the Cu sites [Cu(r)] and only the x/y axis O sites [Ox(r) and Oy(r)]. Phase-resolved Fourier analysis reveals directly that the modulations in the Ox(r) and Oy(r) sublattice images consistently exhibit a relative phase of π. We confirm this discovery on two highly distinct cuprate compounds, ruling out tunnel matrix-element and materials-specific systematics. These observations demonstrate by direct sublattice phase-resolved visualization that the density wave found in underdoped cuprates consists of modulations of the intraunit-cell states that exhibit a predominantly d-symmetry form factor. PMID:24989503

  5. Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8.

    PubMed

    Kumar, Nallani Vijay; Yang, Jianbo; Pillai, Jitesh K; Rawat, Swati; Solano, Carlos; Kumar, Abhay; Grøtli, Morten; Stemmler, Timothy L; Rosen, Barry P; Tamás, Markus J

    2015-12-28

    The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeast Saccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)] in vitro and in vivo and that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.

  6. Purcell factors exceeding 1,000 in directional and efficient plasmonic nanoantennas

    NASA Astrophysics Data System (ADS)

    Akselrod, Gleb; Argyropoulos, Christos; Hoang, Thang; Ciraci, Cristian; Fang, Chao; Huang, Jiani; Smith, David; Mikkelsen, Maiken

    2015-03-01

    To move nanophotonic devices such as nano-lasers, ultrafast LEDs, and single photon sources into the practical realm, a challenging list of requirements must be met, including directional emission, room temperature and broadband operation, and high radiative quantum yield, while having a large spontaneous emission rate. To achieve these features simultaneously, a platform is needed in which the various decay channels of embedded emitters can be fully understood and controlled. In this work we show that all these device requirements can be satisfied by a plasmonic nanoantenna with emitters embedded in the nanoscale gap (~ 10 nm) between a metal film and a silver nanocube. Fluorescence lifetime measurements on ensembles of emitters reveal Purcell factors exceeding 1000 while maintaining high quantum yield (> 0 . 5) and directional emission (84% collection efficiency). Using angle resolved fluorescence measurements, we independently determine the orientations of emission dipoles in the nanoscale gap. By incorporating this information along with the three-dimensional spatial distribution of dipoles into simulations, we predict the emission dynamics in excellent agreement with experiment.

  7. Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

    PubMed Central

    Kumar, Nallani Vijay; Yang, Jianbo; Pillai, Jitesh K.; Rawat, Swati; Solano, Carlos; Kumar, Abhay; Grøtli, Morten; Stemmler, Timothy L.; Rosen, Barry P.

    2015-01-01

    The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeast Saccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)] in vitro and in vivo and that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation. PMID:26711267

  8. Direct Modification of the Proinflammatory Cytokine Macrophage Migration Inhibitory Factor by Dietary Isothiocyanates*

    PubMed Central

    Brown, Kristin K.; Blaikie, Frances H.; Smith, Robin A. J.; Tyndall, Joel D. A.; Lue, Hongqi; Bernhagen, Jürgen; Winterbourn, Christine C.; Hampton, Mark B.

    2009-01-01

    Isothiocyanates are a class of phytochemicals with widely reported anti-cancer and anti-inflammatory activity. However, knowledge of their activity at a molecular level is limited. The objective of this study was to identify biological targets of phenethyl isothiocyanate (PEITC) using an affinity purification approach. An analogue of PEITC was synthesized to enable conjugation to a solid-phase resin. The pleiotropic cytokine macrophage migration inhibitory factor (MIF) was the major protein captured from cell lysates. Site-directed mutagenesis and mass spectrometry showed that PEITC covalently modified the N-terminal proline residue of MIF. This resulted in complete loss of catalytic tautomerase activity and disruption of protein conformation, as determined by impaired recognition by a monoclonal antibody directed to the region that receptors and interacting proteins bind to MIF. The conformational change was supported by in silico modeling. Monoclonal antibody binding to plasma MIF was disrupted in humans consuming watercress, a major dietary source of PEITC. The isothiocyanates have significant potential for development as MIF inhibitors, and this activity may contribute to the biological properties of these phytochemicals. PMID:19776019

  9. Assessing dynamic spectral causality by lagged adaptive directed transfer function and instantaneous effect factor.

    PubMed

    Xu, Haojie; Lu, Yunfeng; Zhu, Shanan; He, Bin

    2014-07-01

    It is of significance to assess the dynamic spectral causality among physiological signals. Several practical estimators adapted from spectral Granger causality have been exploited to track dynamic causality based on the framework of time-varying multivariate autoregressive (tvMVAR) models. The nonzero covariance of the model's residuals has been used to describe the instantaneous effect phenomenon in some causality estimators. However, for the situations with Gaussian residuals in some autoregressive models, it is challenging to distinguish the directed instantaneous causality if the sufficient prior information about the "causal ordering" is missing. Here, we propose a new algorithm to assess the time-varying causal ordering of tvMVAR model under the assumption that the signals follow the same acyclic causal ordering for all time lags and to estimate the instantaneous effect factor (IEF) value in order to track the dynamic directed instantaneous connectivity. The time-lagged adaptive directed transfer function (ADTF) is also estimated to assess the lagged causality after removing the instantaneous effect. In this study, we first investigated the performance of the causal-ordering estimation algorithm and the accuracy of IEF value. Then, we presented the results of IEF and time-lagged ADTF method by comparing with the conventional ADTF method through simulations of various propagation models. Statistical analysis results suggest that the new algorithm could accurately estimate the causal ordering and give a good estimation of the IEF values in the Gaussian residual conditions. Meanwhile, the time-lagged ADTF approach is also more accurate in estimating the time-lagged dynamic interactions in a complex nervous system after extracting the instantaneous effect. In addition to the simulation studies, we applied the proposed method to estimate the dynamic spectral causality on real visual evoked potential (VEP) data in a human subject. Its usefulness in time

  10. Assessing Dynamic Spectral Causality by Lagged Adaptive Directed Transfer Function and Instantaneous Effect Factor

    PubMed Central

    Xu, Haojie; Lu, Yunfeng; Zhu, Shanan

    2014-01-01

    It is of significance to assess the dynamic spectral causality among physiological signals. Several practical estimators adapted from spectral Granger causality have been exploited to track dynamic causality based on the framework of time-varying multivariate autoregressive (tvMVAR) models. The non-zero covariance of the model’s residuals has been used to describe the instantaneous effect phenomenon in some causality estimators. However, for the situations with Gaussian residuals in some autoregressive models, it is challenging to distinguish the directed instantaneous causality if the sufficient prior information about the “causal ordering” is missing. Here, we propose a new algorithm to assess the time-varying causal ordering of tvMVAR model under the assumption that the signals follow the same acyclic causal ordering for all time lags and to estimate the instantaneous effect factor (IEF) value in order to track the dynamic directed instantaneous connectivity. The time-lagged adaptive directed transfer function (ADTF) is also estimated to assess the lagged causality after removing the instantaneous effect. In the present study, we firstly investigated the performance of the causal-ordering estimation algorithm and the accuracy of IEF value. Then, we presented the results of IEF and time-lagged ADTF method by comparing with the conventional ADTF method through simulations of various propagation models. Statistical analysis results suggest that the new algorithm could accurately estimate the causal ordering and give a good estimation of the IEF values in the Gaussian residual conditions. Meanwhile, the time-lagged ADTF approach is also more accurate in estimating the time-lagged dynamic interactions in a complex nervous system after extracting the instantaneous effect. In addition to the simulation studies, we applied the proposed method to estimate the dynamic spectral causality on real visual evoked potential (VEP) data in a human subject. Its usefulness in

  11. Novel chemo-enzymatic oligomers of cinnamic acids as direct and indirect inhibitors of coagulation proteinases.

    PubMed

    Monien, Bernhard H; Henry, Brian L; Raghuraman, Arjun; Hindle, Michael; Desai, Umesh R

    2006-12-01

    Thrombin and factor Xa, two important procoagulant enzymes, have been prime targets for regulation of clotting through the direct and indirect mechanism of inhibition. Our efforts on exploiting the indirect mechanism led us to study a carboxylic acid-based scaffold, which displayed major acceleration in the inhibition of these enzymes [J. Med. Chem.2005, 48, 1269, 5360]. This work advances the study to chemo-enzymatically prepared oligomers of 4-hydroxycinnamic acids, DHPs, which display interesting anticoagulant properties. Oligomers, ranging in size from tetramers to pentadecamers, were prepared through peroxidase-catalyzed oxidative coupling of caffeic, ferulic, and sinapic acids, and sulfated using triethylamine-sulfur trioxide complex. Chromatographic, spectroscopic, and elemental studies suggest that the DHPs are heterogeneous, polydisperse preparations composed of inter-monomer linkages similar to those found in natural lignins. Measurement of activated thromboplastin and prothrombin time indicates that both the sulfated and unsulfated derivatives of the DHPs display anticoagulant activity, which is dramatically higher than that of the reference polyacrylic acids. More interestingly, this activity approaches that of low-molecular-weight heparin with the sulfated derivative showing approximately 2- to 3-fold greater potency than the unsulfated parent. Studies on the inhibition of factor Xa and thrombin indicate that the oligomers exert their anticoagulant effect through both direct and indirect inhibition mechanisms. This dual inhibition property of 4-hydroxycinnamic acid-based DHP oligomers is the first example in inhibitors of coagulation. This work puts forward a novel, non-heparin structure, which may be exploited for the design of potent, dual action inhibitors of coagulation through combinatorial virtual screening on a library of DHP oligomers.

  12. Direct oral anticoagulants: Current indications and unmet needs in the treatment of venous thromboembolism.

    PubMed

    Bertoletti, Laurent; Ollier, Edouard; Duvillard, Cécile; Delavenne, Xavier; Beyens, Marie-Noëlle; De Magalhaes, Elodie; Bellet, Florelle; Basset, Thierry; Mismetti, Patrick; Laporte, Silvy

    2017-04-01

    The treatment of acute venous thromboembolism (VTE) is being completely modified with the development of direct oral anticoagulants (DOACs). Rivaroxaban, apixaban and edoxaban directly inhibit factor Xa, whereas dabigatran inhibits factor IIa. All these drugs are proposed orally, and share pharmacological similarities: fixed doses without any therapeutic drug monitoring, key role of the transporter proteins P-glycoprotein for all of them and metabolism mediated by CYP3A4 for the anti-Xa, short half-life with variable rate of renal elimination. More than 25 000 patients with acute VTE were included in phase-III studies. Rivaroxaban and apixaban challenged all the conventional therapy (parenteral heparins followed by anti-vitamin K antagonists) whereas edoxaban and dabigatran challenged only anti-vitamin K antagonists. All the DOACs met the non-inferiority efficacy endpoint (recurrent VTE during treatment), whereas the large non-inferiority margin was debated for dabigatran. However, they were associated with better safety and a decreased risk of major bleeding. According to indirect comparisons, there were no statistically significant differences between DOACs in terms of efficacy but some differences are not excluded in term of safety. Although DOACs allow for simplification of treatment in the majority of patients with acute VTE, their risk/benefit ratio is questioned in elderly patients, patients with mild-to-severe renal impairment, and in some clinical subgroups such as cancer or chronic thromboembolic pulmonary hypertension. Validated reversal strategies (potentially based on laboratory monitoring) are expected for patients with major bleeding, overdose or with a need for surgery.

  13. Acoustical inverse problems regularization: Direct definition of filter factors using Signal-to-Noise Ratio

    NASA Astrophysics Data System (ADS)

    Gauthier, P.-A.; Gérard, A.; Camier, C.; Berry, A.

    2014-02-01

    Acoustic imaging aims at localization and characterization of sound sources using microphone arrays. In this paper a new regularization method for acoustic imaging by inverse approach is proposed. The method first relies on the singular value decomposition of the plant matrix and on the projection of the measured data on the corresponding singular vectors. In place of regularization using classical methods such as truncated singular value decomposition and Tikhonov regularization, the proposed method involves the direct definition of the filter factors on the basis of a thresholding operation, defined from the estimated measurement noise. The thresholding operation is achieved using modified filter functions. The originality of the approach is to propose the definition of a filter factor which provides more damping to the singular components dominated by noise than that given by the Tikhonov filter. This has the advantage of potentially simplifying the selection of the best regularization amount in inverse problems. Theoretical results show that this method is comparatively more accurate than Tikhonov regularization and truncated singular value decomposition.

  14. Psychosocial factors and sport injuries: prediction, prevention and future research directions.

    PubMed

    Johnson, Urban; Ivarsson, Andreas

    2017-08-01

    This review provides an overview of recent theoretical and empirical developments regarding psychosocial factors related to the prediction and prevention of sport injuries, and highlights some of the most interesting areas of investigation that have been carried out in the past few years. For instance, a systematic review of the most cited and used theoretical framework in the field has recently been performed, which supports the model's suggestion that psychosocial variables, as well as psychologically based interventions, can influence injury risk among athletes. Based on substantial empirical evidence it is also shown that changes in stress and perceived recovery appear to predict injury occurrence in sport. Current studies, focusing on overuse injuries, also suggest that cultural norms and rules can be seen as factors that can indirectly influence the risk of becoming injured. Future research directions are presented such as the need for interdisciplinary injury prevention programs based on a combination of physiological and psychological interventions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Secreted Factors from Colorectal and Prostate Cancer Cells Skew the Immune Response in Opposite Directions

    PubMed Central

    Lundholm, Marie; Hägglöf, Christina; Wikberg, Maria L.; Stattin, Pär; Egevad, Lars; Bergh, Anders; Wikström, Pernilla; Palmqvist, Richard; Edin, Sofia

    2015-01-01

    Macrophage infiltration has been associated with an improved prognosis in patients with colorectal cancer (CRC), but a poor prognosis in prostate cancer (PC) patients. In this study, the distribution and prognostic value of proinflammatory M1 macrophages (NOS2+) and immunosuppressive M2 macrophages (CD163+) was evaluated in a cohort of 234 PC patients. We found that macrophages infiltrating PC were mainly of an M2 type and correlated with a more aggressive tumor and poor patient prognosis. Furthermore, the M1/M2 ratio was significantly decreased in PC compared to CRC. Using in vitro cell culture experiments, we could show that factors secreted from CRC and PC cells induced macrophages of a proinflammatory or immunosuppressive phenotype, respectively. These macrophages differentially affected autologous T lymphocyte proliferation and activation. Consistent with this, CRC specimens were found to have higher degrees of infiltrating T-helper 1 cells and active cytotoxic T lymphocytes, while PC specimens displayed functionally inactive T cells. In conclusion, our results imply that tumour-secreted factors from cancers of different origin can drive macrophage differentiation in opposite directions and thereby regulate the organization of the anti-tumour immune response. Our findings suggest that reprogramming of macrophages could be an important tool in the development of new immunotherapeutic strategies. PMID:26503803

  16. Direct measurement of 11B(p ,γ )12C astrophysical S factors at low energies

    NASA Astrophysics Data System (ADS)

    He, J. J.; Jia, B. L.; Xu, S. W.; Chen, S. Z.; Ma, S. B.; Hou, S. Q.; Hu, J.; Zhang, L. Y.; Yu, X. Q.

    2016-05-01

    We directly measure the absolute cross section of 11B(p ,γ )12C in the energy region of Ec .m .=130 -257 keV by using a thin target for the first time. This work is performed on a 320-kV platform at the Institute of Modern Physics in Lanzhou. The astrophysical S factors of this reaction are obtained for capture to the ground and first excited states of 12C. The properties of the known resonance at ˜150 keV are derived and agree with the previous results. However, in the energy region of 170-240 keV, our S factors are about 15%-50% larger than the adopted values in NACRE II and are also larger than the upper limits of NACRE II by up to ˜20 % . This indicates that our new reaction rate is enhanced by about 15%-50% compared to the NACRE II adopted rate in the temperature region 0.32-0.62 GK.

  17. Peptidyl Prolyl Isomerase PIN1 Directly Binds to and Stabilizes Hypoxia-Inducible Factor-1α

    PubMed Central

    Han, Hyeong-jun; Kwon, Nayoung; Choi, Min-A; Jung, Kyung Oh; Piao, Juan-Yu; Ngo, Hoang Kieu Chi; Kim, Su-Jung; Kim, Do-Hee; Chung, June-Key; Cha, Young-Nam; Youn, Hyewon; Choi, Bu Young; Min, Sang-Hyun; Surh, Young-Joon

    2016-01-01

    Peptidyl prolyl isomerase (PIN1) regulates the functional activity of a subset of phosphoproteins through binding to phosphorylated Ser/Thr-Pro motifs and subsequently isomerization of the phosphorylated bonds. Interestingly, PIN1 is overexpressed in many types of malignancies including breast, prostate, lung and colon cancers. However, its oncogenic functions have not been fully elucidated. Here, we report that PIN1 directly interacts with hypoxia-inducible factor (HIF)-1α in human colon cancer (HCT116) cells. PIN1 binding to HIF-1α occurred in a phosphorylation-dependent manner. We also found that PIN1 interacted with HIF-1α at both exogenous and endogenous levels. Notably, PIN1 binding stabilized the HIF-1α protein, given that their levels were significantly increased under hypoxic conditions. The stabilization of HIF-1α resulted in increased transcriptional activity, consequently upregulating expression of vascular endothelial growth factor, a major contributor to angiogenesis. Silencing of PIN1 or pharmacologic inhibition of its activity abrogated the angiogenesis. By utilizing a bioluminescence imaging technique, we were able to demonstrate that PIN1 inhibition dramatically reduced the tumor volume in a subcutaneous mouse xenograft model and angiogenesis as well as hypoxia-induced transcriptional activity of HIF-1α. These results suggest that PIN1 interacting with HIF-1α is a potential cancer chemopreventive and therapeutic target. PMID:26784107

  18. Brain-derived neurotrophic factor promotes central nervous system myelination via a direct effect upon oligodendrocytes.

    PubMed

    Xiao, Junhua; Wong, Agnes W; Willingham, Melanie M; van den Buuse, Maarten; Kilpatrick, Trevor J; Murray, Simon S

    2010-01-01

    The extracellular factors that are responsible for inducing myelination in the central nervous system (CNS) remain elusive. We investigated whether brain-derived neurotrophic factor (BDNF) is implicated, by first confirming that BDNF heterozygous mice exhibit delayed CNS myelination during early postnatal development. We next established that the influence of BDNF upon myelination was direct, by acting on oligodendrocytes, using co-cultures of dorsal root ganglia neurons and oligodendrocyte precursor cells. Importantly, we found that BDNF retains its capacity to enhance myelination of neurons or by oligodendrocytes derived from p75NTR knockout mice, indicating the expression of p75NTR is not necessary for BDNF-induced myelination. Conversely, we observed that phosphorylation of TrkB correlated with myelination, and that inhibiting TrkB signalling also inhibited the promyelinating effect of BDNF, suggesting that BDNF enhances CNS myelination via activating oligodendroglial TrkB-FL receptors. Together, our data reveal a previously unknown role for BDNF in potentiating the normal development of CNS myelination, via signalling within oligodendrocytes.

  19. The splicing factor PRP2, a putative RNA helicase, interacts directly with pre-mRNA.

    PubMed Central

    Teigelkamp, S; McGarvey, M; Plumpton, M; Beggs, J D

    1994-01-01

    The RNA helicase-like splicing factor PRP2 interacts only transiently with spliceosomes. To facilitate analysis of interactions of PRP2 with spliceosomal components, PRP2 protein was stalled in splicing complexes by two different methods. A dominant negative mutant form of PRP2 protein, which associates stably with spliceosomes, was found to interact directly with pre-mRNAs, as demonstrated by UV-crosslinking experiments. The use of various mutant and truncated pre-mRNAs revealed that this interaction requires a spliceable pre-mRNA and an assembled spliceosome; a 3' splice site is not required. To extend these observations to the wild-type PRP2 protein, spliceosomes were depleted of ATP; PRP2 protein interacts with pre-mRNA in these spliceosomes in an ATP-independent fashion. Comparison of RNA binding by PRP2 protein in the presence of ATP or gamma S-ATP showed that ATP hydrolysis rather than mere ATP binding is required to release PRP2 protein from pre-mRNA. As PRP2 is an RNA-stimulated ATPase, these experiments strongly suggest that the pre-mRNA is the native co-factor stimulating ATP hydrolysis by PRP2 protein in spliceosomes. Since PRP2 is a putative RNA helicase, we propose that the pre-mRNA is the target of RNA displacement activity of PRP2 protein, promoting the first step of splicing. Images PMID:8112302

  20. Activating transcription factor 1 directs Mhem atheroprotective macrophages through coordinated iron handling and foam cell protection.

    PubMed

    Boyle, Joseph J; Johns, Michael; Kampfer, Theresa; Nguyen, Aivi T; Game, Laurence; Schaer, Dominik J; Mason, Justin C; Haskard, Dorian O

    2012-01-06

    Intraplaque hemorrhage (IPH) drives atherosclerosis through the dual metabolic stresses of cholesterol-enriched erythrocyte membranes and pro-oxidant heme/iron. When clearing tissue hemorrhage, macrophages are typically seen storing either iron or lipid. We have recently defined hemorrhage-associated macrophages (HA-mac) as a plaque macrophage population that responds adaptively to IPH. This study aimed to define the key transcription factor(s) involved in HO-1 induction by heme. To address this question, we used microarray analysis and transfection with siRNA and plasmids. To maintain physiological relevance, we focused on human blood-derived monocytes. We found that heme stimulates monocytes through induction of activating transcription factor 1 (ATF-1). ATF-1 coinduces heme oxygenase-1 (HO-1) and Liver X receptor beta (LXR-β). Heme-induced HO-1 and LXR-β were suppressed by knockdown of ATF-1, and HO-1 and LXR-β were induced by ATF-1 transfection. ATF-1 required phosphorylation for full functional activity. Expression of LXR-β in turn led to induction of other genes central to cholesterol efflux, such as LXR-α and ABCA1. This heme-directed state was distinct from known macrophage states (M1, M2, Mox) and, following the same format, we have designated them Mhem. These results show that ATF-1 mediates HO-1 induction by heme and drives macrophage adaptation to intraplaque hemorrhage. Our definition of an ATF-1-mediated pathway for linked protection from foam cell formation and oxidant stress may have therapeutic potential.

  1. Direct phylogenetic evidence for lateral transfer of elongation factor-like gene.

    PubMed

    Kamikawa, Ryoma; Inagaki, Yuji; Sako, Yoshihiko

    2008-05-13

    Genes encoding elongation factor-like (EFL) proteins, which show high similarity to elongation factor-1alpha (EF-1alpha), have been found in phylogenetically distantly related eukaryotes. The sporadic distribution of "EFL-containing" lineages within "EF-1alpha-containing" lineages indirectly, but strongly, suggests lateral gene transfer as the principal driving force in EFL evolution. However, one of the most critical aspects in the above hypothesis, the donor lineages in any putative cases of lateral EFL gene transfer, remained unclear. In this study, we provide direct evidence for lateral transfer of an EFL gene through the analyses of 10 diatom EFL genes. All diatom EFL homologues tightly clustered in phylogenetic analyses, suggesting acquisition of the exogenous EFL gene early in diatom evolution. Our survey additionally identified Thalassiosira pseudonana as a eukaryote bearing EF-1alpha and EFL genes and secondary EFL gene loss in Phaeodactylum tricornutum, the complete genome of which encodes only the EF-1alpha gene. Most importantly, the EFL phylogeny recovered a robust grouping of homologues from diatoms, the cercozoan Bigelowiella natans, and the foraminifer Planoglabratella opecularis, with the diatoms nested within the Bigelowiella plus Planoglabratella (Rhizaria) grouping. The particular relationships recovered are further consistent with two characteristic sequence motifs. The best explanation of our data analyses is an EFL gene transfer from a foraminifer to a diatom, the first case in which the donor-recipient relationship was clarified. Finally, based on a reverse transcriptase quantitative PCR assay and the genome information of Thalassiosira and Phaeodactylum, we propose the loss of elongation factor function in Thalassiosira EF-1alpha.

  2. Direct phylogenetic evidence for lateral transfer of elongation factor-like gene

    PubMed Central

    Kamikawa, Ryoma; Inagaki, Yuji; Sako, Yoshihiko

    2008-01-01

    Genes encoding elongation factor-like (EFL) proteins, which show high similarity to elongation factor-1α (EF-1α), have been found in phylogenetically distantly related eukaryotes. The sporadic distribution of “EFL-containing” lineages within “EF-1α-containing” lineages indirectly, but strongly, suggests lateral gene transfer as the principal driving force in EFL evolution. However, one of the most critical aspects in the above hypothesis, the donor lineages in any putative cases of lateral EFL gene transfer, remained unclear. In this study, we provide direct evidence for lateral transfer of an EFL gene through the analyses of 10 diatom EFL genes. All diatom EFL homologues tightly clustered in phylogenetic analyses, suggesting acquisition of the exogenous EFL gene early in diatom evolution. Our survey additionally identified Thalassiosira pseudonana as a eukaryote bearing EF-1α and EFL genes and secondary EFL gene loss in Phaeodactylum tricornutum, the complete genome of which encodes only the EF-1α gene. Most importantly, the EFL phylogeny recovered a robust grouping of homologues from diatoms, the cercozoan Bigelowiella natans, and the foraminifer Planoglabratella opecularis, with the diatoms nested within the Bigelowiella plus Planoglabratella (Rhizaria) grouping. The particular relationships recovered are further consistent with two characteristic sequence motifs. The best explanation of our data analyses is an EFL gene transfer from a foraminifer to a diatom, the first case in which the donor–recipient relationship was clarified. Finally, based on a reverse transcriptase quantitative PCR assay and the genome information of Thalassiosira and Phaeodactylum, we propose the loss of elongation factor function in Thalassiosira EF-1α. PMID:18458344

  3. Distinguishing direct from indirect roles for bicoid mRNA localization factors

    PubMed Central

    Weil, Timothy T.; Xanthakis, Despina; Parton, Richard; Dobbie, Ian; Rabouille, Catherine; Gavis, Elizabeth R.; Davis, Ilan

    2010-01-01

    Localization of bicoid mRNA to the anterior of the Drosophila oocyte is essential for patterning the anteroposterior body axis in the early embryo. bicoid mRNA localizes in a complex multistep process involving transacting factors, molecular motors and cytoskeletal components that remodel extensively during the lifetime of the mRNA. Genetic requirements for several localization factors, including Swallow and Staufen, are well established, but the precise roles of these factors and their relationship to bicoid mRNA transport particles remains unresolved. Here we use live cell imaging, super-resolution microscopy in fixed cells and immunoelectron microscopy on ultrathin frozen sections to study the distribution of Swallow, Staufen, actin and dynein relative to bicoid mRNA during late oogenesis. We show that Swallow and bicoid mRNA are transported independently and are not colocalized at their final destination. Furthermore, Swallow is not required for bicoid transport. Instead, Swallow localizes to the oocyte plasma membrane, in close proximity to actin filaments, and we present evidence that Swallow functions during the late phase of bicoid localization by regulating the actin cytoskeleton. In contrast, Staufen, dynein and bicoid mRNA form nonmembranous, electron dense particles at the oocyte anterior. Our results exclude a role for Swallow in linking bicoid mRNA to the dynein motor. Instead we propose a model for bicoid mRNA localization in which Swallow is transported independently by dynein and contributes indirectly to bicoid mRNA localization by organizing the cytoskeleton, whereas Staufen plays a direct role in dynein-dependent bicoid mRNA transport. PMID:20023172

  4. Direct covalent modification as a strategy to inhibit nuclear factor-kappa B.

    PubMed

    Pande, Vineet; Sousa, Sérgio F; Ramos, Maria João

    2009-01-01

    Nuclear Factor-KkappaB (NF-kappaB) is a transcription factor whose inappropriate activation may result in the development of a number of diseases including cancer, inflammation, neurodegeneration and AIDS. Recent studies on NF-kappaB mediated pathologies, made therapeutic interventions leading to its inhibition an emerging theme in pharmaceutical research. NF-kappaB resides in the cytoplasm and is activated by several time-dependent factors, leading to proteasome-dependent degradation of its inhibitory protein (IkappaB), resulting in free NF-kappaB (p50 and p65 subunits, involved in disease states), which binds to target DNA sites, further resulting in enhanced transcription of several disease associated proteins. The complex pathway of NF-kappaB, finally leading to its DNA binding, has attracted several approaches interfering with this pathway. One such approach is that of a direct covalent modification of NF-kappaB. In this article, we present a critical review on the pharmacological agents that have been studied as inhibitors of NF-kappaB by covalently modifying redox-regulated cysteine residues in its subunits, ultimately resulting in the inhibition of kappaB DNA recognition and binding. Beginning with a general overview of NF-kappaB pathway and several possibilities of chemical interventions, the significance of redox-regulation in NF-kappaB activation and DNA binding is presented. Further, protein S-thiolation, S-nitrosylation and irreversible covalent modification are described as regular biochemical events in the cell, having provided a guideline for the development of NF-kappaB inhibitors discussed further. Although just a handful of inhibitors, with most of them being alkylating agents have been studied in the present context, this approach presents potential for the development of a new class of NF-kappaB-inhibitors.

  5. Pestivirus Npro Directly Interacts with Interferon Regulatory Factor 3 Monomer and Dimer

    PubMed Central

    Holthauzen, Luis Marcelo F.; Ruggli, Nicolas

    2016-01-01

    ABSTRACT Interferon regulatory factor 3 (IRF3) is a transcription factor involved in the activation of type I alpha/beta interferon (IFN-α/β) in response to viral infection. Upon viral infection, the IRF3 monomer is activated into a phosphorylated dimer, which induces the transcription of interferon genes in the nucleus. Viruses have evolved several ways to target IRF3 in order to subvert the innate immune response. Pestiviruses, such as classical swine fever virus (CSFV), target IRF3 for ubiquitination and subsequent proteasomal degradation. This is mediated by the viral protein Npro that interacts with IRF3, but the molecular details for this interaction are largely unknown. We used recombinant Npro and IRF3 proteins and show that Npro interacts with IRF3 directly without additional proteins and forms a soluble 1:1 complex. The full-length IRF3 but not merely either of the individual domains is required for this interaction. The interaction between Npro and IRF3 is not dependent on the activation state of IRF3, since Npro binds to a constitutively active form of IRF3 in the presence of its transcriptional coactivator, CREB-binding protein (CBP). The results indicate that the Npro-binding site on IRF3 encompasses a region that is unperturbed by the phosphorylation and subsequent activation of IRF3 and thus excludes the dimer interface and CBP-binding site. IMPORTANCE The pestivirus N-terminal protease, Npro, is essential for evading the host's immune system by facilitating the degradation of interferon regulatory factor 3 (IRF3). However, the nature of the Npro interaction with IRF3, including the IRF3 species (inactive monomer versus activated dimer) that Npro targets for degradation, is largely unknown. We show that classical swine fever virus Npro and porcine IRF3 directly interact in solution and that full-length IRF3 is required for interaction with Npro. Additionally, Npro interacts with a constitutively active form of IRF3 bound to its transcriptional

  6. Gender and factor-level interactions in psychopathy: implications for self-directed violence risk and borderline personality disorder symptoms.

    PubMed

    Verona, Edelyn; Sprague, Jenessa; Javdani, Shabnam

    2012-07-01

    Women with antisocial and psychopathic traits have a more extensive history of self-directed violence, as well as borderline personality disorder (BPD) symptoms, than their male counterparts (Chapman, Specht, & Cellucci, 2005; Warren et al., 2003). To inform this area of research, we examined gender differences in the relationship between psychopathy factors and risk for self-directed violence, as measured by a history of suicidal ideation, self-harm, and suicide attempts, across 2 studies. In both studies, we found that the interaction of the interpersonal-affective (Factor 1) and impulsive-antisocial traits (Factor 2) of psychopathy, a combination considered to exemplify high psychopathy, was associated with ideation, self-harm, and suicide attempt histories specifically in women. In men, Factor 2 traits were associated with these risk indices for self-directed violence, regardless of Factor 1. In Study 2, we extended our analysis to examine whether BPD accounted for the relationship between psychopathy and self-directed violence differentially in women and men. Results suggested that BPD symptoms partially accounted for the effects of Factor 2 on self-directed violence (both self-harm and attempts) in both genders but fully accounted for Factor 1 protective effects only in men. These findings underscore the notion that the same psychopathic trait liabilities, at least as they are currently assessed, may confer risk for different forms of behavioral maladjustment in women versus men. PsycINFO Database Record (c) 2012 APA, all rights reserved.

  7. NELL-1, an osteoinductive factor, is a direct transcriptional target of Osterix.

    PubMed

    Chen, Feng; Zhang, Xinli; Sun, Shan; Zara, Janette N; Zou, Xuan; Chiu, Robert; Culiat, Cymbelin T; Ting, Kang; Soo, Chia

    2011-01-01

    NELL-1 is a novel secreted protein associated with premature fusion of cranial sutures in craniosynostosis that has been found to promote osteoblast cell differentiation and mineralization. Our previous study showed that Runx2, the key transcription factor in osteoblast differentiation, transactivates the NELL-1 promoter. In this study, we evaluated the regulatory involvement and mechanisms of Osterix, an essential transcription factor of osteoblasts, in NELL-1 gene expression and function. Promoter analysis showed a cluster of potential Sp1 sites (Sp1/Osterix binding sites) within approximately 70 bp (from -71 to -142) of the 5' flanking region of the human NELL-1 transcriptional start site. Luciferase activity in our NELL-1 promoter reporter systems was significantly decreased in Saos-2 cells when Osterix was overexpressed. Mutagenesis study demonstrated that this suppression is mediated by the Sp1 sites. The binding specificity of Osterix to these Sp1 sites was confirmed in Saos-2 cells and primary human osteoblasts by EMSA in vitro and ChIP assay in vivo. ChIP assay also showed that Osterix downregulated NELL-1 by affecting binding of RNA polymerase II to the NELL-1 promoter, but not by competing with Runx2 binding to the OSE2 sites. Moreover, NELL-1 mRNA levels were significantly decreased when Osterix was overexpressed in Saos-2, U2OS, Hela and Glioma cells. Correspondingly, knockdown of Osterix increased NELL-1 transcription and osteoblastic differentiation in both Saos-2 cells and primary human osteoblasts. These results suggest that Osterix is a direct transcriptional regulator with repressive effect on NELL-1 gene expression, contributing to a delicate balance of regulatory effects on NELL-1 transcription with Runx2, and may play a crucial role in osteoblast differentiation and mineralization. These findings also extend our understanding of the molecular mechanism of Runx2, Osterix, and NELL-1 and demonstrate their crosstalk during osteogenesis.

  8. NELL-1, an Osteoinductive Factor, Is a Direct Transcriptional Target of Osterix

    PubMed Central

    Sun, Shan; Zara, Janette N.; Zou, Xuan; Chiu, Robert; Culiat, Cymbelin T.; Ting, Kang; Soo, Chia

    2011-01-01

    NELL-1 is a novel secreted protein associated with premature fusion of cranial sutures in craniosynostosis that has been found to promote osteoblast cell differentiation and mineralization. Our previous study showed that Runx2, the key transcription factor in osteoblast differentiation, transactivates the NELL-1 promoter. In this study, we evaluated the regulatory involvement and mechanisms of Osterix, an essential transcription factor of osteoblasts, in NELL-1 gene expression and function. Promoter analysis showed a cluster of potential Sp1 sites (Sp1/Osterix binding sites) within approximately 70 bp (from −71 to −142) of the 5′ flanking region of the human NELL-1 transcriptional start site. Luciferase activity in our NELL-1 promoter reporter systems was significantly decreased in Saos-2 cells when Osterix was overexpressed. Mutagenesis study demonstrated that this suppression is mediated by the Sp1 sites. The binding specificity of Osterix to these Sp1 sites was confirmed in Saos-2 cells and primary human osteoblasts by EMSA in vitro and ChIP assay in vivo. ChIP assay also showed that Osterix downregulated NELL-1 by affecting binding of RNA polymerase II to the NELL-1 promoter, but not by competing with Runx2 binding to the OSE2 sites. Moreover, NELL-1 mRNA levels were significantly decreased when Osterix was overexpressed in Saos-2, U2OS, Hela and Glioma cells. Correspondingly, knockdown of Osterix increased NELL-1 transcription and osteoblastic differentiation in both Saos-2 cells and primary human osteoblasts. These results suggest that Osterix is a direct transcriptional regulator with repressive effect on NELL-1 gene expression, contributing to a delicate balance of regulatory effects on NELL-1 transcription with Runx2, and may play a crucial role in osteoblast differentiation and mineralization. These findings also extend our understanding of the molecular mechanism of Runx2, Osterix, and NELL-1 and demonstrate their crosstalk during osteogenesis

  9. Pathogenicity Island Cross Talk Mediated by Recombination Directionality Factors Facilitates Excision from the Chromosome

    PubMed Central

    Carpenter, Megan R.; Rozovsky, Sharon

    2015-01-01

    ABSTRACT Pathogenicity islands (PAIs) are mobile integrated genetic elements (MIGEs) that contain a diverse range of virulence factors and are essential in the evolution of pathogenic bacteria. PAIs are widespread among bacteria and integrate into the host genome, commonly at a tRNA locus, via integrase-mediated site-specific recombination. The excision of PAIs is the first step in the horizontal transfer of these elements and is not well understood. In this study, we examined the role of recombination directionality factors (RDFs) and their relationship with integrases in the excision of two PAIs essential for Vibrio cholerae host colonization: Vibrio pathogenicity island 1 (VPI-1) and VPI-2. VPI-1 does not contain an RDF, which allowed us to answer the question of whether RDFs are an absolute requirement for excision. We found that an RDF was required for efficient excision of VPI-2 but not VPI-1 and that RDFs can induce excision of both islands. Expression data revealed that the RDFs act as transcriptional repressors to both VPI-1- and VPI-2-encoded integrases. We demonstrated that the RDFs Vibrio excision factor A (VefA) and VefB bind at the attachment sites (overlapping the int promoter region) of VPI-1 and VPI-2, thus supporting this mode of integrase repression. In addition, V. cholerae RDFs are promiscuous due to their dual functions of promoting excision of both VPI-1 and VPI-2 and acting as negative transcriptional regulators of the integrases. This is the first demonstration of cross talk between PAIs mediated via RDFs which reveals the complex interactions that occur between separately acquired MIGEs. IMPORTANCE Deciphering the mechanisms of pathogenicity island excision is necessary for understanding the evolution and spread of these elements to their nonpathogenic counterparts. Such mechanistic insight would assist in predicting the mobility of uncharacterized genetic elements. This study identified extensive RDF-mediated cross talk between two

  10. Tetracycline does not directly inhibit the function of bacterial elongation factor Tu.

    PubMed

    Gzyl, Katherine E; Wieden, Hans-Joachim

    2017-01-01

    Understanding the molecular mechanism of antibiotics that are currently in use is important for the development of new antimicrobials. The tetracyclines, discovered in the 1940s, are a well-established class of antibiotics that still have a role in treating microbial infections in humans. It is generally accepted that the main target of their action is the ribosome. The estimated affinity for tetracycline binding to the ribosome is relatively low compared to the actual potency of the drug in vivo. Therefore, additional inhibitory effects of tetracycline on the translation machinery have been discussed. Structural evidence suggests that tetracycline inhibits the function of the essential bacterial GTPase Elongation Factor (EF)-Tu through interaction with the bound nucleotide. Based on this, tetracycline has been predicted to impede the nucleotide-binding properties of EF-Tu. However, detailed kinetic studies addressing the effect of tetracycline on nucleotide binding have been prevented by the fluorescence properties of the antibiotic. Here, we report a fluorescence-based kinetic assay that minimizes the effect of tetracycline autofluorescence, enabling the detailed kinetic analysis of the nucleotide-binding properties of Escherichia coli EF-Tu. Furthermore, using physiologically relevant conditions, we demonstrate that tetracycline does not affect EF-Tu's intrinsic or ribosome-stimulated GTPase activity, nor the stability of the EF-Tu•GTP•Phe-tRNAPhe complex. We therefore provide clear evidence that tetracycline does not directly impede the function of EF-Tu.

  11. NRC-interacting factor directs neurite outgrowth in an activity-dependent manner.

    PubMed

    Zhao, X-S; Fu, W-Y; Hung, K-W; Chien, W W Y; Li, Z; Fu, A K; Ip, N Y

    2015-03-19

    Nuclear hormone receptor coregulator-interacting factor 1 (NIF-1) is a zinc finger nuclear protein that was initially identified to enhance nuclear hormone receptor transcription via its interaction with nuclear hormone receptor coregulator (NRC). NIF-1 may regulate gene transcription either by modulating general transcriptional machinery or remodeling chromatin structure through interactions with specific protein partners. We previously reported that the cytoplasmic/nuclear localization of NIF-1 is regulated by the neuronal Cdk5 activator p35, suggesting potential neuronal functions for NIF-1. The present study reveals that NIF-1 plays critical roles in regulating neuronal morphogenesis at early stages. NIF-1 was prominently expressed in the nuclei of developing rat cortical neurons. Knockdown of NIF-1 expression attenuated both neurite outgrowth in cultured cortical neurons and retinoic acid (RA)-treated Neuro-2a neuroblastoma cells. Furthermore, activity-induced Ca(2+) influx, which is critical for neuronal morphogenesis, stimulated the nuclear localization of NIF-1 in cortical neurons. Suppression of NIF-1 expression reduced the up-regulation of neuronal activity-dependent gene transcription. These findings collectively suggest that NIF-1 directs neuronal morphogenesis during early developmental stages through modulating activity-dependent gene transcription.

  12. Nurse-Administered, Gut-Directed Hypnotherapy in IBS: Efficacy and Factors Predicting a Positive Response.

    PubMed

    Lövdahl, Jenny; Ringström, Gisela; Agerforz, Pia; Törnblom, Hans; Simrén, Magnus

    2015-07-01

    Hypnotherapy is an effective treatment in irritable bowel syndrome (IBS). It is often delivered by a psychotherapist and is costly and time consuming. Nurse-administered hypnotherapy could increase availability and reduce costs. In this study the authors evaluate the effectiveness of nurse-administered, gut-directed hypnotherapy and identify factors predicting treatment outcome. Eighty-five patients were included in the study. Participants received hypnotherapy by a nurse once/week for 12 weeks. Patients reported marked improvement in gastrointestinal (GI) and extra-colonic symptoms after treatment, as well as a reduction in GI-specific anxiety, general anxiety, and depression. Fifty-eight percent were responders after the 12 weeks treatment period, and of these 82% had a favorable clinical response already at week 6. Women were more likely than men to respond favorably to the treatment. Nurse-administered hypnotherapy is an effective treatment for IBS. Being female and reporting a favorable response to treatment by week 6 predicted a positive treatment response at the end of the 12 weeks treatment period.

  13. The contribution of interindividual factors to variability of response in transcranial direct current stimulation studies

    PubMed Central

    Li, Lucia M.; Uehara, Kazumasa; Hanakawa, Takashi

    2015-01-01

    There has been an explosion of research using transcranial direct current stimulation (tDCS) for investigating and modulating human cognitive and motor function in healthy populations. It has also been used in many studies seeking to improve deficits in disease populations. With the slew of studies reporting “promising results” for everything from motor recovery after stroke to boosting memory function, one could be easily seduced by the idea of tDCS being the next panacea for all neurological ills. However, huge variability exists in the reported effects of tDCS, with great variability in the effect sizes and even contradictory results reported. In this review, we consider the interindividual factors that may contribute to this variability. In particular, we discuss the importance of baseline neuronal state and features, anatomy, age and the inherent variability in the injured brain. We additionally consider how interindividual variability affects the results of motor-evoked potential (MEP) testing with transcranial magnetic stimulation (TMS), which, in turn, can lead to apparent variability in response to tDCS in motor studies. PMID:26029052

  14. Exchange factors directly activated by cAMP mediate melanocortin 4 receptor-induced gene expression

    PubMed Central

    Glas, Evi; Mückter, Harald; Gudermann, Thomas; Breit, Andreas

    2016-01-01

    Gs protein-coupled receptors regulate many vital body functions by activation of cAMP response elements (CRE) via cAMP-dependent kinase A (PKA)-mediated phosphorylation of the CRE binding protein (CREB). Melanocortin 4 receptors (MC4R) are prototypical Gs-coupled receptors that orchestrate the hypothalamic control of food-intake and metabolism. Remarkably, the significance of PKA for MC4R-induced CRE-dependent transcription in hypothalamic cells has not been rigorously interrogated yet. In two hypothalamic cell lines, we observed that blocking PKA activity had only weak or no effects on reporter gene expression. In contrast, inhibitors of exchange factors directly activated by cAMP-1/2 (EPAC-1/2) mitigated MC4R-induced CRE reporter activation and mRNA induction of the CREB-dependent genes c-fos and thyrotropin-releasing hormone. Furthermore, we provide first evidence that extracellular-regulated kinases-1/2 (ERK-1/2) activated by EPACs and not PKA are the elusive CREB kinases responsible for MC4R-induced CREB/CRE activation in hypothalamic cells. Overall, these data emphasize the pivotal role of EPACs rather than PKA in hypothalamic gene expression elicited by a prototypical Gs-coupled receptor. PMID:27612207

  15. Identification of factors involved in target RNA-directed microRNA degradation

    PubMed Central

    Haas, Gabrielle; Cetin, Semih; Messmer, Mélanie; Chane-Woon-Ming, Béatrice; Terenzi, Olivier; Chicher, Johana; Kuhn, Lauriane; Hammann, Philippe; Pfeffer, Sébastien

    2016-01-01

    The mechanism by which micro (mi)RNAs control their target gene expression is now well understood. It is however less clear how the level of miRNAs themselves is regulated. Under specific conditions, abundant and highly complementary target RNA can trigger miRNA degradation by a mechanism involving nucleotide addition and exonucleolytic degradation. One such mechanism has been previously observed to occur naturally during viral infection. To date, the molecular details of this phenomenon are not known. We report here that both the degree of complementarity and the ratio of miRNA/target abundance are crucial for the efficient decay of the small RNA. Using a proteomic approach based on the transfection of biotinylated antimiRNA oligonucleotides, we set to identify the factors involved in target-mediated miRNA degradation. Among the retrieved proteins, we identified members of the RNA-induced silencing complex, but also RNA modifying and degradation enzymes. We further validate and characterize the importance of one of these, the Perlman Syndrome 3′-5′ exonuclease DIS3L2. We show that this protein interacts with Argonaute 2 and functionally validate its role in target-directed miRNA degradation both by artificial targets and in the context of mouse cytomegalovirus infection. PMID:26809675

  16. Transcription Factor Rational Design Improves Directed Differentiation of Human Mesenchymal Stem Cells Into Skeletal Myocytes

    PubMed Central

    Gonçalves, Manuel AFV; Janssen, Josephine M; Nguyen, Quynh G; Athanasopoulos, Takis; Hauschka, Stephen D; Dickson, George; de Vries, Antoine AF

    2011-01-01

    There is great interest in transdifferentiating cells from one lineage into those of another and in dedifferentiating mature cells back into a stem/progenitor cell state by deploying naturally occurring transcription factors (TFs). Often, however, steering cellular differentiation pathways in a predictable and efficient manner remains challenging. Here, we investigated the principle of combining domains from different lineage-specific TFs to improve directed cellular differentiation. As proof-of-concept, we engineered the whole-human TF MyoDCD, which has the NH2-terminal transcription activation domain (TAD) and adjacent DNA-binding motif of MyoD COOH-terminally fused to the TAD of myocardin (MyoCD). We found via reporter gene and marker protein assays as well as by a cell fusion readout system that, targeting the TAD of MyoCD to genes normally responsive to the skeletal muscle-specific TF MyoD enforces more robust myogenic reprogramming of nonmuscle cells than that achieved by the parental, prototypic master TF, MyoD. Human mesenchymal stem cells (hMSCs) transduced with a codon-optimized microdystrophin gene linked to a synthetic striated muscle-specific promoter and/or with MyoD or MyoDCD were evaluated for complementing the genetic defect in Duchenne muscular dystrophy (DMD) myocytes through heterotypic cell fusion. Cotransduction of hMSCs with MyoDCD and microdystrophin led to chimeric myotubes containing the highest dystrophin levels. PMID:21266958

  17. Field Measurements of Gasoline Direct Injection Emission Factors: Spatial and Seasonal Variability.

    PubMed

    Zimmerman, Naomi; Wang, Jonathan M; Jeong, Cheol-Heon; Ramos, Manuel; Hilker, Nathan; Healy, Robert M; Sabaliauskas, Kelly; Wallace, James S; Evans, Greg J

    2016-02-16

    Four field campaigns were conducted between February 2014 and January 2015 to measure emissions from light-duty gasoline direct injection (GDI) vehicles (2013 Ford Focus) in an urban near-road environment in Toronto, Canada. Measurements of CO2, CO, NOx, black carbon (BC), benzene, toluene, ethylbenzene-xylenes (BTEX), and size-resolved particle number (PN) were recorded 15 m from the roadway and converted to fuel-based emission factors (EFs). Other than for NOx and CO, the GDI engine had elevated emissions compared to the Toronto fleet, with BC EFs in the 73rd percentile, BTEX EFs in the 80-90th percentile, and PN EFs in the 75th percentile during wintertime measurements. Additionally, for three campaigns, a second platform for measuring PN and CO2 was placed 1.5-3 m from the roadway to quantify changes in PN with distance from point of emission. GDI vehicle PN EFs were found to increase by up to 240% with increasing distance from the roadway, predominantly due to an increasing fraction of sub-40 nm particles. PN and BC EFs from the same engine technology were also measured in the laboratory. BC EFs agreed within 20% between the laboratory and real-world measurements; however, laboratory PN EFs were an order of magnitude lower due to exhaust conditioning.

  18. [Analysis of the Cochrane Review: Direct thrombin inhibitors versus vitamin K antagonists for preventing cerebral or systemic embolism in people with non-valvular atrial fibrillation. Cochrane Database Syst Rev. 2014,3:CD009893].

    PubMed

    Vaz Carneiro, António; Costa, João

    2014-01-01

    Ischemic stroke is one of the most important complications of lone (non-valvular) atrial fibrillation. Its prevention is usually accomplished through oral anticoagulation. Until a few years ago warfarin was the most used agent, but recently two new pharmacologic classes have been introduced for stroke prevention in these patients: oral direct thrombin inhibitors (dabigatran and ximelagatran) and oral factor Xa inhibitors (rivaroxaban, apixaban and edoxaban). In this systematic review, oral direct thrombin inhibitors were compared with warfarin for efficacy and safety. The results indicate that there is no difference in terms of efficacy (except dabigatran 150 mg BID). Oral direct thrombin inhibitors presented less hemorrhages but increased treatment withdrawal due to adverse side-effects (the authors performed post-hoc analyses excluding ximelagatran because this drug was withdrawn from the market owing to safety concerns). There was no difference in terms of mortality between the agents.

  19. Direct inguinal hernias and anterior surgical approach are risk factors for female inguinal hernia recurrences.

    PubMed

    Burcharth, Jakob; Andresen, Kristoffer; Pommergaard, Hans-Christian; Bisgaard, Thue; Rosenberg, Jacob

    2014-01-01

    The purpose of this study was to establish the risk of recurrence after direct and indirect inguinal hernia operation in a large-scale female population and to establish the relationship between the type of hernia at the primary and recurrent procedure. Using data from the Danish Hernia Database (DHDB), a cohort was generated: all females operated on electively for a primary inguinal hernia by either Lichtenstein’s technique or laparoscopy from 1998 to 2012. Within this prospectively collected cohort, the hernia type at the primary procedure (direct inguinal hernia (DIH), indirect inguinal hernia (IIH), combination hernia), the hernia type at the recurrent procedure (DIH, IIH, combination hernia, femoral hernia), anesthesia type, and time from primary procedure to reoperation were registered. A total of 5,893 females with primary elective inguinal hernia operation on in the study period (61 % IIH, 37 % DIH, 2 % combined hernias) were included with a median follow-up time of 72 months (range 0 to 169). A total of 305 operations for suspected recurrences were registered (61 % inguinal recurrences, 38 % femoral recurrences, 1 % no hernias), which corresponded to an overall reoperation rate of 5.2 %. All femoral recurrences occurred after a previous open anterior operation. The crude reoperation rate after primary DIH operation was 11.0 %, 3.0 % after primary IIH operation and 0.007 % after combined hernia operation (p < 0.001). The multivariate adjusted analysis found that DIH at primary operation was a substantial risk factor for recurrence with a hazard ratio of 3.1 (CI 95 % 2.4–3.9) compared with IIH at primary operation (p < 0.001), and that laparoscopic operation gave a lower risk of recurrence with a hazard ratio of 0.57 (CI 95 % 0.43–0.75) compared with Lichtenstein’s technique (p < 0.001). The risk of femoral recurrence was correlated to operation for DIH with a hazard ratio of 2.4 (CI 95 % 1.7–3.5) compared with operation for IIH. In a

  20. Antigenicity of recombinant maltose binding protein-Mycobacterium avium subsp. paratuberculosis fusion proteins with and without factor Xa cleaving

    USDA-ARS?s Scientific Manuscript database

    Mycobacterium avium subsp paratuberculosis (MAP) causes Johne’s disease (JD) in ruminants. Proteomic studies have shown that MAP expresses certain proteins when exposed to in vitro physiological stress conditions similar to the conditions experienced within a host during natural infection. Such prot...

  1. Improvement of low bioavailability of a novel factor Xa inhibitor through formulation of cationic additives in its oral dosage form.

    PubMed

    Fujii, Yoshimine; Kanamaru, Taro; Kikuchi, Hiroshi; Nakagami, Hiroaki; Yamashita, Shinji; Akashi, Mitsuru; Sakuma, Shinji

    2011-12-15

    A clinical trial of (2S)-2-[4-[[(3S)-1-acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3-(7-amidino-2-naphtyl) propanoic acid (DX-9065) revealed that its oral bioavailability was only 3% when it was administered as a conventional capsule formulation. The low bioavailability of DX-9065 was likely caused by both its poor membrane permeability and its electrostatic interaction with anionic bile acids. We hypothesized that DX-9065 absorption would be enhanced when the cationic drug was free from the complex through its replacement with other cationic substances. Polystyrene nanospheres coated with cationic poly(vinylamine) and cholestyramine, which is clinically used as a cholesterol-lowering agent, dramatically prevented DX-9065 from interacting with chenodeoxycholic acid in vitro. Successive animal experiments showed that bioavailability of DX-9065 administered with these cationic substances was 2-3 times that of DX-9065 administered solely. A dry syrup formulation with one-half of a minimal cholesterol-lowering equivalent dose of cholestyramine was designed, and the clinical trial was resumed. A 1.3-fold increase in bioavailability of DX-9065 was observed when the dry syrup was administered. We successfully demonstrated that DX-9065 absorption was enhanced when the drug was administered with cationic additives; however, it appeared that the absorption-enhancing function of cholestyramine largely depended on its dose. The dose escalation is probably prerequisite for the significant improvement of DX-9065 absorption in humans.

  2. Comparison of postoperative complications after total hip arthroplasty among patients receiving aspirin, enoxaparin, warfarin, and factor Xa inhibitors.

    PubMed

    Agaba, Perez; Kildow, Beau J; Dhotar, Herman; Seyler, Thorsten M; Bolognesi, Michael

    2017-12-01

    Optimal prophylaxis for prevention of venous thromboembolism (VTE) after total joint arthroplasty (TJA) remains debated. The purpose of this study was to compare postoperative complications in patients receiving different VTE chemoprophylactic regimens. Using a nationwide healthcare database, 72,670 THA patients without a history of VTE were identified. Study cohorts received VTE prophylaxis within 30 days postoperatively. Odds ratios and 95% confidence intervals were used to assess 30-day and 90-day postoperative complications (hematoma, hemorrhage, transfusion, pulmonary embolism (PE), VTE, prosthetic joint infection (PJI), and incision/drainage (I&D)). Of the 72,670 THA patients, 25,966 received single medication VTE prophylaxis; 551 (2.12%) aspirin, 6791 (26.15%) enoxaparin, 12,008 (46.25%) warfarin, 5403 (20.81%) rivaroxaban, 876 (3.37%) fondaparinux and 337 (1.30%) apixaban. 30-day complications included; aspirin: I&D; warfarin: I&D, hematoma, hemorrhage, transfusion, PJI, PE and DVT; apixaban: hematoma and hemorrhage. 90-day complications included; aspirin: I&D; warfarin: I&D, hematoma, hemorrhage, transfusion, PJI, PE and DVT. Warfarin was the only anticoagulant associated with a higher risk for DVT, and the highest risk for 30-day and 90-day complications. Aspirin had the highest risk for I&D. Despite three times increased 30-day risk for bleeding, apixaban was effective in preventing VTE during the high-risk 3-month-period. Enoxaparin had the lowest risk for PE and DVT while rivaroxaban had the lowest risk for PJI, hematoma, I&D, hemorrhage and transfusion.

  3. The transcription factor paired box-5 promotes osteoblastogenesis through direct induction of Osterix and Osteocalcin.

    PubMed

    Hinoi, Eiichi; Nakatani, Eri; Yamamoto, Tomomi; Iezaki, Takashi; Takahata, Yoshifumi; Fujita, Hiroyuki; Ishiura, Ryo; Takamori, Misa; Yoneda, Yukio

    2012-12-01

    Although skeletal abnormalities are seen in mice deficient of particular paired box (Pax) family proteins, little attention has been paid to their role in osteoblastogenesis so far. Here, we investigated the possible involvement of several Pax family members in mechanisms underlying the regulation of differentiation and maturation of osteoblasts. Among different Pax family members tested, Pax5 was not markedly expressed in murine calvarial osteoblasts before culture, but progressively expressed by osteoblasts under differentiation toward maturation. Immunoreactive Pax5 was highly detectable in primary cultured mature osteoblasts on immunoblotting and in osteoblastic cells attached to cancellous bone in mouse tibial sections on immunohistochemistry, respectively. Knockdown by small interfering RNA (siRNA) of endogenous Pax5 led to significant inhibition of the expression of Osteocalcin, and Osterix through deterioration of gene transactivation, in addition to a1(I)Collagen expression and alkaline phosphatase (ALP) staining, without affecting runt-related transcription factor-2 (Runx2) expression and cell viability in osteoblastic MC3T3-E1 cells. The introduction of Pax5 enhanced promoter activities of Osteocalcin and Osterix in a manner dependent on the paired domain in MC3T3-E1 cells. Putative Pax5 binding sites were identified in the 5'-flanking regions of mouse Osteocalcin and Osterix, whereas chromatin immunoprecipitation assay revealed the direct binding of Pax5 to particular regions of Osteocalcin and Osterix promoters in MC3T3-E1 cells. Overexpression of Pax5 significantly increased Osteocalcin, Osterix, and a1(I)Collagen expression, ALP activity, and Ca(2+) accumulation, without affecting Runx2 expression, in MC3T3-E1 cells. In vertebrae of transgenic mice predominantly expressing Pax5 in osteoblasts, a significant increase was seen in the ratio of bone volume over tissue volume and the bone formation rate. These findings suggest that Pax5 could positively

  4. Both mosquito-derived xanthurenic acid and a host blood-derived factor regulate gametogenesis of Plasmodium in the midgut of the mosquito.

    PubMed

    Arai, M; Billker, O; Morris, H R; Panico, M; Delcroix, M; Dixon, D; Ley, S V; Sinden, R E

    2001-08-01

    Gametogenesis of Plasmodium in vitro can be induced by the combined stimulus of a 5 degrees C fall in temperature and the presence of xanthurenic acid (XA). In-vitro experiments showed that P. gallinaceum (EC(50)=80 nM) is much more sensitive to XA than P. berghei (9 microM), P. yoelii (8 microM), and P. falciparum (2 microM). However, in the mosquito vector, we do not know whether the temperature shift and XA are the only gametocyte-activating factors (GAF), nor do we know with certainty the true source(s) of XA in the mosquito blood meal. Previous studies indicate that XA is the only source of GAF in the mosquito. By defining, and then contrasting, the ability of an XA-deficient mutant of Aedes aegypti, with the wild-type mosquito to support exflagellation and ookinete formation in vivo, we determined the roles of parasite-, mosquito- and host blood-derived GAF in the regulation of gametogenesis of P. gallinaceum. Removal of both host and vector sources of GAF totally inhibited both exflagellation and ookinete production, whilst the lack of either single source resulted in only a partial reduction of exflagellation and ookinete formation in the mosquito gut. Both sources can be effectively replaced/substituted by synthetic XA. This suggests (1) both mosquito- and vertebrate-derived factors act as GAF in the mosquito gut in vivo; (2) the parasite itself is unable to produce any significant GAF activity. Studies are underway to determine whether vertebrate-derived GAF is XA. These data may form the basis of further studies of the development of new methods of interrupting malarial transmission.

  5. Hantaviruses direct endothelial cell permeability by sensitizing cells to the vascular permeability factor VEGF, while angiopoietin 1 and sphingosine 1-phosphate inhibit hantavirus-directed permeability.

    PubMed

    Gavrilovskaya, Irina N; Gorbunova, Elena E; Mackow, Natalie A; Mackow, Erich R

    2008-06-01

    Hantaviruses infect human endothelial cells and cause two vascular permeability-based diseases: hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Hantavirus infection alone does not permeabilize endothelial cell monolayers. However, pathogenic hantaviruses inhibit the function of alphav beta3 integrins on endothelial cells, and hemorrhagic disease and vascular permeability deficits are consequences of dysfunctional beta3 integrins that normally regulate permeabilizing vascular endothelial growth factor (VEGF) responses. Here we show that pathogenic Hantaan, Andes, and New York-1 hantaviruses dramatically enhance the permeability of endothelial cells in response to VEGF, while the nonpathogenic hantaviruses Prospect Hill and Tula have no effect on endothelial cell permeability. Pathogenic hantaviruses directed endothelial cell permeability 2 to 3 days postinfection, coincident with pathogenic hantavirus inhibition of alphav beta3 integrin functions, and hantavirus-directed permeability was inhibited by antibodies to VEGF receptor 2 (VEGFR2). These studies demonstrate that pathogenic hantaviruses, similar to alphav beta3 integrin-deficient cells, specifically enhance VEGF-directed permeabilizing responses. Using the hantavirus permeability assay we further demonstrate that the endothelial-cell-specific growth factor angiopoietin 1 (Ang-1) and the platelet-derived lipid mediator sphingosine 1-phosphate (S1P) inhibit hantavirus directed endothelial cell permeability at physiologic concentrations. These results demonstrate the utility of a hantavirus permeability assay and rationalize the testing of Ang-1, S1P, and antibodies to VEGFR2 as potential hantavirus therapeutics. The central importance of beta3 integrins and VEGF responses in vascular leak and hemorrhagic disease further suggest that altering beta3 or VEGF responses may be a common feature of additional viral hemorrhagic diseases. As a result, our findings provide a potential mechanism

  6. Mutating factor VIII: lessons from structure to function.

    PubMed

    Fay, Philip J; Jenkins, P Vincent

    2005-01-01

    Factor VIII, a metal ion-dependent heterodimer, circulates in complex with von Willebrand factor. At sites of vessel wall damage, this procofactor is activated to factor VIIIa by limited proteolysis and assembles onto an anionic phospholipid surface in complex with factor IXa to form the intrinsic factor Xase; an enzyme complex that efficiently converts factor X to factor Xa during the propagation phase of coagulation. Factor Xase activity is down-regulated by mechanisms that include self-dampening by dissociation of a critical factor VIIIa subunit and proteolytic inactivation by the activated protein C pathway. Recent studies identify putative metal ion coordination sites as well as ligands involved in the catabolism of the activated and procofactor forms of the protein. Our knowledge of these multiple intra- and inter-molecular interactions has been facilitated by the application of naturally occurring and site-directed mutations to study factor VIII structure and function. In this review, we document important and novel contributions following this line of investigation.

  7. A comparison of red blood cell transfusion utilization between anti-activated factor X and activated partial thromboplastin monitoring in patients receiving unfractionated heparin.

    PubMed

    Belk, K W; Laposata, M; Craver, C

    2016-11-01

    Essentials Anti-activated factor X (Anti-Xa) monitoring is more precise than activated partial thromboplastin (aPTT). 20 804 hospitalized cardiovascular patients monitored with Anti-Xa or aPTT were analyzed. Adjusted transfusion rates were significantly lower for patients monitored with Anti-Xa. Adoption of Anti-Xa protocols could reduce transfusions among cardiovascular patients in the US. Background Anticoagulant activated factor X protein (Anti-Xa) has been shown to be a more precise monitoring tool than activated partial thromboplastin time (aPTT) for patients receiving unfractionated heparin (UFH) anticoagulation therapy. Objectives To compare red blood cell (RBC) transfusions between patients receiving UFH who are monitored with Anti-Xa and those monitored with aPTT. Patients/Methods A retrospective cohort study was conducted on patients diagnosed with acute coronary syndrome (ACS) (N = 14 822), diagnosed with ischemic stroke (STK) (N = 1568) or with a principal diagnosis of venous thromboembolism (VTE) (N = 4414) in the MedAssets data from January 2009 to December 2013. Anti-Xa and aPTT groups were identified from hospital billing details, with both brand and generic name as search criteria. Propensity score techniques were used to match Anti-Xa cases to aPTT controls. RBC transfusions were identified from hospital billing data. Multivariable logistic regression was used to identify significant drivers of transfusions. Results Anti-Xa patients had fewer RBC transfusions than aPTT patients in the ACS population (difference 17.5%; 95% confidence interval [CI] 16.4-18.7%), the STK population (difference 8.2%; 95% CI 4.4-11.9%), and the VTE population (difference 4.7%; 95% CI 3.3-6.1%). After controlling for patient age and gender, diagnostic risks (e.g. anemia, renal insufficiency, and trauma), and invasive procedures (e.g. cardiac catheterization, hemodialysis, and coronary artery bypass graft), Anti-Xa patients were less likely to have a transfusion while

  8. Protein-Templated Formation of an Inhibitor of the Blood Coagulation Factor Xa through a Background-Free Amidation Reaction.

    PubMed

    Jaegle, Mike; Steinmetzer, Torsten; Rademann, Jörg

    2017-03-20

    Protein-templated reactions enable the target-guided formation of protein ligands from reactive fragments, ideally with no background reaction. Herein, we investigate the templated formation of amides. A nucleophilic fragment that binds to the coagulation factor Xa was incubated with the protein and thirteen differentially activated dipeptides. The protein induced a non-catalytic templated reaction for the phenyl and trifluoroethyl esters; the latter was shown to be a completely background-free reaction. Starting from two fragments with millimolar affinity, a 29 nm superadditive inhibitor of factor Xa was obtained. The fragment ligation reaction was detected with high sensitivity by an enzyme activity assay and by mass spectrometry. The reaction progress and autoinhibition of the templated reaction by the formed ligation product were determined, and the structure of the protein-inhibitor complex was elucidated.

  9. Protein‐Templated Formation of an Inhibitor of the Blood Coagulation Factor Xa through a Background‐Free Amidation Reaction

    PubMed Central

    Jaegle, Mike; Steinmetzer, Torsten

    2017-01-01

    Abstract Protein‐templated reactions enable the target‐guided formation of protein ligands from reactive fragments, ideally with no background reaction. Herein, we investigate the templated formation of amides. A nucleophilic fragment that binds to the coagulation factor Xa was incubated with the protein and thirteen differentially activated dipeptides. The protein induced a non‐catalytic templated reaction for the phenyl and trifluoroethyl esters; the latter was shown to be a completely background‐free reaction. Starting from two fragments with millimolar affinity, a 29 nm superadditive inhibitor of factor Xa was obtained. The fragment ligation reaction was detected with high sensitivity by an enzyme activity assay and by mass spectrometry. The reaction progress and autoinhibition of the templated reaction by the formed ligation product were determined, and the structure of the protein–inhibitor complex was elucidated. PMID:28199769

  10. Transgenic expression of the rice Xa21 pattern-recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum.

    PubMed

    Tripathi, Jaindra N; Lorenzen, Jim; Bahar, Ofir; Ronald, Pamela; Tripathi, Leena

    2014-08-01

    Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  11. Preparation and characterization of members of the system La 2- xA1+ xCu 2O 6± y where A = Ca,Sr

    NASA Astrophysics Data System (ADS)

    Doverspike, K.; Liu, J.-H.; Dwight, K.; Wold, A.

    1989-09-01

    Members of the system La 2- xA1+ xCu 2O 6± y, where A = Ca,Sr, were prepared by decomposition of the nitrates. The tolerance of these compounds for oxygen uptake, as well as the ease of substitution for the A-site ions, is shown to be closely related to the distribution of the alkaline-earth ions on the 8- and 9-coordinated A-sites.

  12. 42 CFR 413.80 - Direct GME payments: Determination of weighting factors for foreign medical graduates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., the National Board of Medical Examiners Examination, Parts I and II, may be substituted for FMGEMS for... factors for foreign medical graduates. 413.80 Section 413.80 Public Health CENTERS FOR MEDICARE & MEDICAID... weighting factors for foreign medical graduates. (a) The weighting factor for a foreign medical graduate...

  13. 42 CFR 413.80 - Direct GME payments: Determination of weighting factors for foreign medical graduates.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., the National Board of Medical Examiners Examination, Parts I and II, may be substituted for FMGEMS for... factors for foreign medical graduates. 413.80 Section 413.80 Public Health CENTERS FOR MEDICARE & MEDICAID... weighting factors for foreign medical graduates. (a) The weighting factor for a foreign medical graduate...

  14. Boundary magnetization properties of epitaxial C r2 -xA lxO3 thin films

    NASA Astrophysics Data System (ADS)

    Fallarino, Lorenzo; Binek, Christian; Berger, Andreas

    2015-06-01

    The magnetoelectric antiferromagnet α -C r2O3 (chromia) is known to possess a roughness insensitive net equilibrium magnetization at the (0001) surface, called boundary magnetization (BM), which is coupled to the bulk antiferromagnetic order parameter. In order to verify whether this symmetry sensitive BM persists in alloys, we investigate the impact of diamagnetic dilution on chromia thin films alloyed with the isostructural α -A l2O3 (alumina). Single-crystalline C r2 -xA lxO3 thin films with (0001) surface orientation and varying stoichiometry have been grown by sputter codeposition in the concentration range between x =0 and x =0.6 . For these samples, we find the corundum crystal structure, the antiferromagnetic ordering, and the boundary magnetization to be preserved. We also find that the critical temperature TN can be tuned by alloying with α -A l2O3 , using the BM as a probe to study the magnetic phase transition. Furthermore, we were able to evaluate the critical exponent and the absolute BM values for different samples. Both properties corroborate that the observed magnetic signals originate from the BM rather than the bulk of the samples.

  15. Evaluation of the Williamsburg County Direct Instruction Program: Factors Leading to Success in Rural Elementary Programs.

    ERIC Educational Resources Information Center

    Darch, Craig; And Others

    Several evaluation formats were used to examine the impact that the Direct Instruction Model had on 600 selected students in Williamsburg County, South Carolina, over a 7-year period. The performance of students in the Direct Instruction Model was contrasted with the performance of similar students (on the basis of family income, ethnicity,…

  16. Motivational Factors in Self-Directed Informal Learning from Online Learning Resources

    ERIC Educational Resources Information Center

    Song, Donggil; Bonk, Curtis J.

    2016-01-01

    Learning is becoming more self-directed and informal with the support of emerging technologies. A variety of online resources have promoted informal learning by allowing people to learn on demand and just when needed. It is significant to understand self-directed informal learners' motivational aspects, their learning goals, obstacles, and…

  17. The Factor Structure of the Self-Directed Learning Readiness Scale (SDLRS).

    ERIC Educational Resources Information Center

    Wang, Xiaoping; And Others

    A study involving teachers and administrators from 16 elementary, middle, and high schools in Tennessee investigated the factorial structure of the Self-Directed Learning Readiness Scale (SDLRS). The SDLRS includes 58 Likert-like items designed to measure the readiness of adult learners to assume self-direction in the learning process. Study…

  18. Direct and indirect effects of neighborhood factors and self-care on glycemic control in adults with type 2 diabetes.

    PubMed

    Smalls, Brittany L; Gregory, Chris M; Zoller, James S; Egede, Leonard E

    2015-03-01

    To determine whether neighborhood factors have direct or indirect effects, via self-care behaviors on glycemic control. Adult patients with type 2 diabetes were recruited from an academic medical center and Veterans Affairs Medical Center in the southeastern United States. Confirmatory factor analysis was used to create latent variables for neighborhood factors and diabetes self-care behavior. Structural equation modeling was used to test direct and indirect effects between neighborhood factors and glycemic control as assessed by HbA1c levels. CFA yielded four latent variables for neighborhood factors (neighborhood violence, access to healthy food, social support, and neighborhood aesthetics) and one latent variable diabetes self-care. We found that social support (β=0.28, z=4.86, p<0.001) and access to healthy foods (β=-0.17, z=-2.95, p=0.003) had direct effects on self-care; self-care (β=-0.15, z=-2.48, p=0.013) and neighborhood aesthetics (β=0.12, z=2.19, p=0.03) had direct effects on glycemic control; while social support (β=-0.04, z=-2.26, p=0.02) had an indirect effect on glycemic control via self-care. This study showed that self-care behaviors and neighborhood aesthetics have direct effects on glycemic control, social support and access to health foods had direct effects on self-care, and social support had an indirect effect on glycemic control via self-care. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Enhancing the Thermostability of Serratia plymuthica Sucrose Isomerase Using B-Factor-Directed Mutagenesis

    PubMed Central

    Ai, Yixin; Wu, Jing

    2016-01-01

    The sucrose isomerase of Serratia plymuthica AS9 (AS9 PalI) was expressed in Escherichia coli BL21(DE3) and characterized. The half-life of AS9 PalI was 20 min at 45°C, indicating that it was unstable. In order to improve its thermostability, six amino acid residues with higher B-factors were selected as targets for site-directed mutagenesis, and six mutants (E175N, K576D, K174D, G176D, S575D and N577K) were designed using the RosettaDesign server. The E175N and K576D mutants exhibited improved thermostability in preliminary experiments, so the double mutant E175N/K576D was constructed. These three mutants (E175N, K576D, E175N/K576D) were characterized in detail. The results indicate that the three mutants exhibit a slightly increased optimal temperature (35°C), compared with that of the wild-type enzyme (30°C). The mutants also share an identical pH optimum of 6.0, which is similar to that of the wild-type enzyme. The half-lives of the E175N, K576D and E175N/K576D mutants were 2.30, 1.78 and 7.65 times greater than that of the wild-type enzyme at 45°C, respectively. Kinetic studies showed that the Km values for the E175N, K576D and E175N/K576D mutants decreased by 6.6%, 2.0% and 11.0%, respectively, and their kcat/Km values increased by 38.2%, 4.2% and 19.4%, respectively, compared with those of the wild-type enzyme. After optimizing the conditions for isomaltulose production at 45°C, we found that the E175N, K576D and E175N/K576D mutants displayed slightly improved isomaltulose yields, compared with the wild-type enzyme. Therefore, the mutants produced in this study would be more suitable for industrial biosynthesis of isomaltulose. PMID:26886729

  20. Enhancing the Thermostability of Serratia plymuthica Sucrose Isomerase Using B-Factor-Directed Mutagenesis.

    PubMed

    Duan, Xuguo; Cheng, Sheng; Ai, Yixin; Wu, Jing

    2016-01-01

    The sucrose isomerase of Serratia plymuthica AS9 (AS9 PalI) was expressed in Escherichia coli BL21(DE3) and characterized. The half-life of AS9 PalI was 20 min at 45°C, indicating that it was unstable. In order to improve its thermostability, six amino acid residues with higher B-factors were selected as targets for site-directed mutagenesis, and six mutants (E175N, K576D, K174D, G176D, S575D and N577K) were designed using the RosettaDesign server. The E175N and K576D mutants exhibited improved thermostability in preliminary experiments, so the double mutant E175N/K576D was constructed. These three mutants (E175N, K576D, E175N/K576D) were characterized in detail. The results indicate that the three mutants exhibit a slightly increased optimal temperature (35°C), compared with that of the wild-type enzyme (30°C). The mutants also share an identical pH optimum of 6.0, which is similar to that of the wild-type enzyme. The half-lives of the E175N, K576D and E175N/K576D mutants were 2.30, 1.78 and 7.65 times greater than that of the wild-type enzyme at 45°C, respectively. Kinetic studies showed that the Km values for the E175N, K576D and E175N/K576D mutants decreased by 6.6%, 2.0% and 11.0%, respectively, and their kcat/Km values increased by 38.2%, 4.2% and 19.4%, respectively, compared with those of the wild-type enzyme. After optimizing the conditions for isomaltulose production at 45°C, we found that the E175N, K576D and E175N/K576D mutants displayed slightly improved isomaltulose yields, compared with the wild-type enzyme. Therefore, the mutants produced in this study would be more suitable for industrial biosynthesis of isomaltulose.

  1. Bivariate Gaussian bridges: directional factorization of diffusion in Brownian bridge models.

    PubMed

    Kranstauber, Bart; Safi, Kamran; Bartumeus, Frederic

    2014-01-01

    In recent years high resolution animal tracking data has become the standard in movement ecology. The Brownian Bridge Movement Model (BBMM) is a widely adopted approach to describe animal space use from such high resolution tracks. One of the underlying assumptions of the BBMM is isotropic diffusive motion between consecutive locations, i.e. invariant with respect to the direction. Here we propose to relax this often unrealistic assumption by separating the Brownian motion variance into two directional components, one parallel and one orthogonal to the direction of the motion. Our new model, the Bivariate Gaussian bridge (BGB), tracks movement heterogeneity across time. Using the BGB and identifying directed and non-directed movement within a trajectory resulted in more accurate utilisation distributions compared to dynamic Brownian bridges, especially for trajectories with a non-isotropic diffusion, such as directed movement or Lévy like movements. We evaluated our model with simulated trajectories and observed tracks, demonstrating that the improvement of our model scales with the directional correlation of a correlated random walk. We find that many of the animal trajectories do not adhere to the assumptions of the BBMM. The proposed model improves accuracy when describing the space use both in simulated correlated random walks as well as observed animal tracks. Our novel approach is implemented and available within the "move" package for R.

  2. Expression of DDX3 Is Directly Modulated by Hypoxia Inducible Factor-1 Alpha in Breast Epithelial Cells

    PubMed Central

    Botlagunta, Mahendran; Krishnamachary, Balaji; Vesuna, Farhad; Winnard, Paul T.; Bol, Guus M.; Patel, Arvind H.; Raman, Venu

    2011-01-01

    DEAD box protein, DDX3, is aberrantly expressed in breast cancer cells ranging from weakly invasive to aggressive phenotypes and functions as an important regulator of cancer cell growth and survival. Here, we demonstrate that hypoxia inducible factor-1α is a transcriptional activator of DDX3 in breast cancer cells. Within the promoter region of the human DDX3 gene, we identified three putative hypoxia inducible factor-1 responsive elements. By luciferase reporter assays in combination with mutated hypoxia inducible factor-1 responsive elements, we determined that the hypoxia inducible factor-1 responsive element at position -153 relative to the translation start site is essential for transcriptional activation of DDX3 under hypoxic conditions. We also demonstrated that hypoxia inducible factor-1 binds to the DDX3 promoter and that the binding is specific, as revealed by siRNA against hypoxia inducible factor-1 and chromatin immunoprecipitation assays. Thus, the activation of DDX3 expression during hypoxia is due to the direct binding of hypoxia inducible factor-1 to hypoxia responsive elements in the DDX3 promoter. In addition, we observed a significant overlap in the protein expression pattern of hypoxia inducible factor-1α and DDX3 in MDA-MB-231 xenograft tumors. Taken together, our results demonstrate, for the first time, the role of DDX3 as a hypoxia-inducible gene that exhibits enhanced expression through the interaction of hypoxia inducible factor-1 with hypoxia inducible factor-1 responsive elements in its promoter region. PMID:21448281

  3. Factors Influencing Direct-Care Paraprofessionals' Decisions to Initiate Mental Health Referrals for Adults with Mental Retardation

    ERIC Educational Resources Information Center

    Oliver, Matthew N. I.; Miller, Trisha T.; Skillman, Gemma D.

    2005-01-01

    Direct-care paraprofessionals' recognition of psychopathology of varying severity in persons with mental retardation was evaluated. Factors that may influence paraprofessionals' decisions to initiate referrals for mental health services on behalf of individuals with mental retardation were also evaluated. Results suggest that staff members…

  4. Pharmacokinetics of danaparoid sodium, dalteparin sodium and heparin determined by inhibitory effect on the activated coagulation factor X activity after single intravenous administration in rabbits.

    PubMed

    Ishida, M; Nakada, Y; Horiuchi, M; Sakamoto, F

    1998-08-01

    The inhibitory effect on the activated coagulation factor X activity (anti-Xa activity) in plasma and urine of danaparoid sodium (DAS, CAS 9005-49-6) was compared with that of dalteparin sodium (DLS, CAS 9041-08-1) and heparin (CAS 9005-49-6) after single intravenous administration at a dose of 640 anti-Xa U/kg to male rabbits. The elimination of half-life of DAS was 9.90 h and was 6.0 times longer than that of DLS and 16.5 times longer than that of heparin. The area under the plasma concentration-time curve (AUC) of DAS was 47.13 +/- 14.55 anti-Xa U.h/ml and was 2.4 times larger than that of DLS and 2.9 times larger than that of heparin. The urinary cumulative excretion of anti-Xa activity of DAS and DLS was 42.6 +/- 6.4% and 16.4 +/- 0.8% of dose, respectively, in 24 h after dosing, respectively. But the anti-Xa activity in urine was not detected at any sampling points after administration of heparin. DAS has a longer elimination half-life and a higher renal excretion of anti-Xa activity than that of DLS and heparin. Therefore, in comparison to DLS and heparin, it seems that the anticoagulant activity of DAS has a long duration.

  5. Epidermal growth factor receptor relocalization and kinase activity are necessary for directional migration of keratinocytes in DC electric fields.

    PubMed

    Fang, K S; Ionides, E; Oster, G; Nuccitelli, R; Isseroff, R R

    1999-06-01

    Human keratinocytes migrate towards the negative pole in DC electric fields of physiological strength. This directional migration is promoted by epidermal growth factor (EGF). To investigate how EGF and its receptor (EGFR) regulate this directionality, we first examined the effect of protein tyrosine kinase inhibitors, including PD158780, a specific inhibitor for EGFR, on this response. At low concentrations, PD158780 inhibited keratinocyte migration directionality, but not the rate of migration; at higher concentrations, it reduced the migration rate as well. The less specific inhibitors, genistein, lavendustin A and tyrphostin B46, reduced the migration rate, but did not affect migration directionality. These data suggest that inhibition of EGFR kinase activity alone reduces directed motility, and inhibition of multiple tyrosine kinases, including EGFR, reduces the cell migration rate. EGFR redistribution also correlates with directional migration. EGFR concentrated on the cathodal face of the cell as early as 5 minutes after exposure to electric fields. PD158780 abolished EGFR localization to the cathodal face. These data suggest that EGFR kinase activity and redistribution in the plasma membrane are required for the directional migration of keratinocytes in DC electric fields. This study provides the first insights into the mechanisms of directed cell migration in electric fields.

  6. Factors associated with the direction of ocular deviation in sensory horizontal strabismus and unilateral organic ocular problems.

    PubMed

    Kim, In Geun; Park, Jung Min; Lee, Soo Jung

    2012-06-01

    To evaluate factors associated with the direction of horizontal deviation in the sensory strabismus of patients with unilateral organic amblyopia. The medical charts of 53 patients who had been diagnosed with sensory strabismus between 2000 and 2009 were reviewed retrospectively. The underlying ocular disease, time of onset and the duration of vision impairment, refractive error and axial length of the fixing eye, and the direction and angle of deviation were analyzed to determine the distribution of underlying diseases and any factors relevant to determining the direction of the horizontal deviation. Congenital cataracts were the most common underlying disease, found in 33 patients, followed by acquired cataracts, optic nerve disorders, retinal detachment, glaucoma and lens subluxation. Among the 50 patients with horizontal strabismus, 11 had esotropia and 39 had exotropia. The incidence of esotropia was significantly higher when the fixing eye had hyperopia or emmetropia, than when the eye was myopic. Age of onset of vision deterioration and at diagnosis of sensory strabismus, and the axial length of the fixing eye had no relationship to the direction of horizontal deviation. In addition, the duration of visual impairment had no significant relationship with the direction or extent of horizontal deviation. The most common cause of sensory strabismus was congenital cataracts and the most frequent type of strabismus was exotropia. With respect to the direction of horizontal strabismus, esotropia occurred significantly more often when the refractive error of the fixing eye was hyperopia or emmetropia than when the fixing eye was myopic.

  7. Architectural constraints are a major factor reducing path integration accuracy in the rat head direction cell system.

    PubMed

    Page, Hector J I; Walters, Daniel; Stringer, Simon M

    2015-01-01

    Head direction cells fire to signal the direction in which an animal's head is pointing. They are able to track head direction using only internally-derived information (path integration)In this simulation study we investigate the factors that affect path integration accuracy. Specifically, two major limiting factors are identified: rise time, the time after stimulation it takes for a neuron to start firing, and the presence of symmetric non-offset within-layer recurrent collateral connectivity. On the basis of the latter, the important prediction is made that head direction cell regions directly involved in path integration will not contain this type of connectivity; giving a theoretical explanation for architectural observations. Increased neuronal rise time is found to slow path integration, and the slowing effect for a given rise time is found to be more severe in the context of short conduction delays. Further work is suggested on the basis of our findings, which represent a valuable contribution to understanding of the head direction cell system.

  8. Architectural constraints are a major factor reducing path integration accuracy in the rat head direction cell system

    PubMed Central

    Page, Hector J. I.; Walters, Daniel; Stringer, Simon M.

    2015-01-01

    Head direction cells fire to signal the direction in which an animal's head is pointing. They are able to track head direction using only internally-derived information (path integration)In this simulation study we investigate the factors that affect path integration accuracy. Specifically, two major limiting factors are identified: rise time, the time after stimulation it takes for a neuron to start firing, and the presence of symmetric non-offset within-layer recurrent collateral connectivity. On the basis of the latter, the important prediction is made that head direction cell regions directly involved in path integration will not contain this type of connectivity; giving a theoretical explanation for architectural observations. Increased neuronal rise time is found to slow path integration, and the slowing effect for a given rise time is found to be more severe in the context of short conduction delays. Further work is suggested on the basis of our findings, which represent a valuable contribution to understanding of the head direction cell system. PMID:25705190

  9. Degree and Direction of Multiple Career Factors: Sex Differences and Construct Validity.

    ERIC Educational Resources Information Center

    Shaffer, Michal; And Others

    Personality, environment, and the interaction between them have been suggested as the major factors accounting for career development. Students (N=283) were asked to respond to 28 items on a recently revised self-report instrument, the Career Factor Checklist (CFC), in order to establish the construct validity of the revised CFC and to investigate…

  10. Degree and Direction of Multiple Career Factors: Sex Differences and Construct Validity.

    ERIC Educational Resources Information Center

    Shaffer, Michal; And Others

    Personality, environment, and the interaction between them have been suggested as the major factors accounting for career development. Students (N=283) were asked to respond to 28 items on a recently revised self-report instrument, the Career Factor Checklist (CFC), in order to establish the construct validity of the revised CFC and to investigate…

  11. Impacts of environmental factors to bi-directional 2×40 Gb/s WDM free-space optical communication

    NASA Astrophysics Data System (ADS)

    Liaw, Shien-Kuei; Hsu, Kuang-Yu; Yeh, Jai-Ger; Lin, Yu-Ming; Yu, Yi-Lin

    2017-08-01

    Bi-directional short-range free-space optical (FSO) communication with bi-directional 2×4×10 Gb/s wavelength division multiplexing (WDM) channel signals is demonstrated by using a transmission distance of 25 m. The single-mode-fiber components are used in the optical terminals for both optical transmitting and receiving functions. The measured power penalties for the 25-m bi-directional four-channel FSO communication compared with the back-to-back link and uni-directional transmission system are less than 0.8 dB and 0.2 dB, respectively. The environmental factor effects, including the oblique incidence through the building window glasses, thermally induced non-uniform air index as well as rainfall on the FSO performance are investigated and analyzed. The experimental results show that rainfall is influential for free space optical transmission.

  12. PPKs mediate direct signal transfer from pytochrome photreceptors to transdcription factor PIF3

    USDA-ARS?s Scientific Manuscript database

    Upon light-induced nuclear translocation, phytochrome (phy) sensory photoreceptors interact with, and induce rapid phosphorylation and consequent ubiquitin-mediated degradation of, transcription factors, called PIFs, thereby regulating target gene expression and plant development. Nevertheless, the ...

  13. Factors that augment the role of direct retainers in mandibular distal-extension removable partial dentures.

    PubMed

    Donahue, T J

    1988-12-01

    Several features of RPD design that augment direct retainer design were identified. They are as follows: 1. The duplication of direct retainer function by other prosthesis components 2. Physiologic adjustment of the framework to assure contacts with abutment teeth that are consistent with the design and intended functions of the components and that transfer stress in a manner those teeth are designed to accept 3. Intimate adaptation of denture bases to the residual mucosa, with recall visits to monitor this adaptation 4. Specific loading of the denture bases through selective placement of artificial teeth 5. Splinting of abutment teeth

  14. Evaluation of the Williamsburg County Direct Instruction Program: Factors Leading to Success in Rural Elementary Programs.

    ERIC Educational Resources Information Center

    Darch, Craig; And Others

    1987-01-01

    Presents evaluation studies examining use of Direct Instruction (DI) Model on rural South Carolina students. Compares results of DI and conventional methods in reading, mathematics, language, and spelling. Results show DI students outperformed local comparison students on virtually every measure. (TES)

  15. e-Portfolios Enhancing Students' Self-Directed Learning: A Systematic Review of Influencing Factors

    ERIC Educational Resources Information Center

    Beckers, Jorrick; Dolmans, Diana; Van Merriënboer, Jeroen

    2016-01-01

    e-Portfolios have become increasingly popular among educators as learning tools. Some research even shows that e-portfolios can be utilised to facilitate the development of skills for self-directed learning. Such skills include self-assessment of performance, formulation of learning goals, and selection of future tasks. However, it is not yet…

  16. Discussion as a factor in racial disparity in advance directive completion at nursing home admission.

    PubMed

    Rich, Shayna E; Gruber-Baldini, Ann L; Quinn, Charlene C; Zimmerman, Sheryl I

    2009-01-01

    Studies have consistently shown racial disparities in advance directive completion for nursing home residents but have not examined whether this disparity is due to differences in interactions with healthcare providers. This study had two aims: to determine whether the racial disparity in advance directive completion by nursing home residents is related to differences in discussion of treatment restrictions with healthcare providers and to examine whether there is a racial disparity in perceptions of residents' significant others that additional discussions would be helpful. Participants were 2,171 white or black (16% of sample) residents newly admitted to 59 nursing homes. Data were collected from structured interviews with residents' significant others and review of nursing home charts. Questions included whether advance directives were completed, whether treatment restrictions were discussed with the resident or family, and whether more discussion would have been helpful. Frequencies according to race were determined for each question; P-values and logistic regression models were obtained. Black residents were less likely to have completed any advance directives (P<.001), and they (P<.001) and their family members (P<.001) were less likely than whites to have discussed treatment restrictions with healthcare providers. Logistic regression models indicated that disparity in treatment restrictions narrowed when these discussions occurred. Significant others of black residents were more likely than those of white residents to consider further discussion helpful (P<.001), especially with physicians. Racial disparity in treatment restrictions may be due in part to a difference in discussion with healthcare providers; increasing discussion may narrow this disparity.

  17. e-Portfolios Enhancing Students' Self-Directed Learning: A Systematic Review of Influencing Factors

    ERIC Educational Resources Information Center

    Beckers, Jorrick; Dolmans, Diana; Van Merriënboer, Jeroen

    2016-01-01

    e-Portfolios have become increasingly popular among educators as learning tools. Some research even shows that e-portfolios can be utilised to facilitate the development of skills for self-directed learning. Such skills include self-assessment of performance, formulation of learning goals, and selection of future tasks. However, it is not yet…

  18. The role of chromatin accessibility in directing the widespread, overlapping patterns of Drosophila transcription factor binding

    PubMed Central

    2011-01-01

    Background In Drosophila embryos, many biochemically and functionally unrelated transcription factors bind quantitatively to highly overlapping sets of genomic regions, with much of the lowest levels of binding being incidental, non-functional interactions on DNA. The primary biochemical mechanisms that drive these genome-wide occupancy patterns have yet to be established. Results Here we use data resulting from the DNaseI digestion of isolated embryo nuclei to provide a biophysical measure of the degree to which proteins can access different regions of the genome. We show that the in vivo binding patterns of 21 developmental regulators are quantitatively correlated with DNA accessibility in chromatin. Furthermore, we find that levels of factor occupancy in vivo correlate much more with the degree of chromatin accessibility than with occupancy predicted from in vitro affinity measurements using purified protein and naked DNA. Within accessible regions, however, the intrinsic affinity of the factor for DNA does play a role in determining net occupancy, with even weak affinity recognition sites contributing. Finally, we show that programmed changes in chromatin accessibility between different developmental stages correlate with quantitative alterations in factor binding. Conclusions Based on these and other results, we propose a general mechanism to explain the widespread, overlapping DNA binding by animal transcription factors. In this view, transcription factors are expressed at sufficiently high concentrations in cells such that they can occupy their recognition sequences in highly accessible chromatin without the aid of physical cooperative interactions with other proteins, leading to highly overlapping, graded binding of unrelated factors. PMID:21473766

  19. AquaPathogen X--A template database for tracking field isolates of aquatic pathogens

    USGS Publications Warehouse

    Emmenegger, Evi; Kurath, Gael

    2012-01-01

    AquaPathogen X is a template database for recording information on individual isolates of aquatic pathogens and is available for download from the U.S. Geological Survey (USGS) Western Fisheries Research Center (WFRC) website (http://wfrc.usgs.gov). This template database can accommodate the nucleotide sequence data generated in molecular epidemiological studies along with the myriad of abiotic and biotic traits associated with isolates of various pathogens (for example, viruses, parasites, or bacteria) from multiple aquatic animal host species (for example, fish, shellfish, or shrimp). The simultaneous cataloging of isolates from different aquatic pathogens is a unique feature to the AquaPathogen X database, which can be used in surveillance of emerging aquatic animal diseases and clarification of main risk factors associated with pathogen incursions into new water systems. As a template database, the data fields are empty upon download and can be modified to user specifications. For example, an application of the template database that stores the epidemiological profiles of fish virus isolates, called Fish ViroTrak (fig. 1), was also developed (Emmenegger and others, 2011).

  20. High fill-factor multilevel Fresnel zone plate arrays by femtosecond laser direct writing

    NASA Astrophysics Data System (ADS)

    Niu, Li-Gang; Wang, Dian; Jiang, Tong; Wu, Si-Zhu; Li, Ai-Wu; Song, Jun-Feng

    2011-02-01

    Fresnel zone plate arrays (FZPAs), as a kind of an important integrated micro-optical device, have attracted great attention. However, the fill factor of present FZPAs by femtosecond technology is a little low, which leads to serious light loss and low signal-to-noise. Here we reported high fill-factor square and hexagonal FZPAs by femtosecond laser two-photon polymerization of the resin SU-8. Their optical focusing and imaging properties showed the high uniformity and high fidelity of these FZPAs. Moreover, 100% fill-factor FZPAs were demonstrated by optimal theoretical design and experimental parameters. With this high quality FZPAs, clear imaging "F" was obtained. At last, high-level phase type FZPAs were prepared to further enhance the diffractive efficiency to as much as 75%.

  1. Isl1 is a direct transcriptional target of Forkhead transcription factors in second heart field-derived mesoderm

    PubMed Central

    Kang, Jione; Nathan, Elisha; Xu, Shan-Mei; Tzahor, Eldad; Black, Brian L.

    2009-01-01

    The cells of the second heart field (SHF) contribute to the outflow tract and right ventricle, as well as to parts of the left ventricle and atria. Isl1, a member of the LIM-homeodomain transcription factor family, is expressed early in this cardiac progenitor population and functions near the top of a transcriptional pathway essential for heart development. Isl1 is required for the survival and migration of SHF-derived cells into the early developing heart at the inflow and outflow poles. Despite this important role for Isl1 in early heart formation, the transcriptional regulation of Isl1 has remained largely undefined. Therefore, to identify transcription factors that regulate Isl1 expression in vivo, we screened the conserved noncoding sequences from the mouse Isl1 locus for enhancer activity in transgenic mouse embryos. Here, we report the identification of an enhancer from the mouse Isl1 gene that is sufficient to direct expression to the SHF and its derivatives. The Isl1 SHF enhancer contains three consensus Forkhead transcription factor binding sites that are efficiently and specifically bound by Forkhead transcription factors. Importantly, the activity of the enhancer is dependent on these three Forkhead binding sites in transgenic mouse embryos. Thus, these studies demonstrate that Isl1 is a direct transcriptional target of Forkhead transcription factors in the SHF and establish a transcriptional pathway upstream of Isl1 in the SHF. PMID:19580802

  2. A comparison of policy and direct practice stakeholder perceptions of factors affecting evidence-based practice implementation using concept mapping.

    PubMed

    Green, Amy E; Aarons, Gregory A

    2011-09-07

    The goal of this study was to assess potential differences between administrators/policymakers and those involved in direct practice regarding factors believed to be barriers or facilitating factors to evidence-based practice (EBP) implementation in a large public mental health service system in the United States. Participants included mental health system county officials, agency directors, program managers, clinical staff, administrative staff, and consumers. As part of concept mapping procedures, brainstorming groups were conducted with each target group to identify specific factors believed to be barriers or facilitating factors to EBP implementation in a large public mental health system. Statements were sorted by similarity and rated by each participant in regard to their perceived importance and changeability. Multidimensional scaling, cluster analysis, descriptive statistics and t-tests were used to analyze the data. A total of 105 statements were distilled into 14 clusters using concept-mapping procedures. Perceptions of importance of factors affecting EBP implementation varied between the two groups, with those involved in direct practice assigning significantly higher ratings to the importance of Clinical Perceptions and the impact of EBP implementation on clinical practice. Consistent with previous studies, financial concerns (costs, funding) were rated among the most important and least likely to change by both groups. EBP implementation is a complex process, and different stakeholders may hold different opinions regarding the relative importance of the impact of EBP implementation. Implementation efforts must include input from stakeholders at multiple levels to bring divergent and convergent perspectives to light.

  3. Direct Inhibition of Hypoxia-Inducible Transcription Factor Complex with Designed Dimeric Epidithiodiketopiperazine

    PubMed Central

    Block, Katherine M.; Wang, Hui; Szabo, Lajos Z.; Polaske, Nathan W.; Henchey, Laura K.; Dubey, Ramin; Kushal, Swati; Laszlo, Csaba F.; Makhoul, Joshua; Song, Zuohe; Meuillet, Emmanuelle J.; Olenyuk, Bogdan Z.

    2009-01-01

    Selective blockade of hypoxia-inducible gene expression by designed small molecules would prove valuable in suppressing tumor angiogenesis, metastasis and altered energy metabolism. We report the design, synthesis, and biological evaluation of dimeric epidithiodiketopiperazine (ETP) small molecule transcriptional antagonist targeting the interaction of the p300/CBP coactivator with the transcription factor HIF-1α. Our results indicate that disrupting this interaction results in rapid downregulation of hypoxia-inducible genes critical for cancer progression. The observed effects are compound-specific and dose-dependent. Controlling gene expression with designed small molecules targeting the transcription factor-coactivator interface may represent a new approach for arresting tumor growth. PMID:20000859

  4. Directional Variance Adjustment: Bias Reduction in Covariance Matrices Based on Factor Analysis with an Application to Portfolio Optimization

    PubMed Central

    Bartz, Daniel; Hatrick, Kerr; Hesse, Christian W.; Müller, Klaus-Robert; Lemm, Steven

    2013-01-01

    Robust and reliable covariance estimates play a decisive role in financial and many other applications. An important class of estimators is based on factor models. Here, we show by extensive Monte Carlo simulations that covariance matrices derived from the statistical Factor Analysis model exhibit a systematic error, which is similar to the well-known systematic error of the spectrum of the sample covariance matrix. Moreover, we introduce the Directional Variance Adjustment (DVA) algorithm, which diminishes the systematic error. In a thorough empirical study for the US, European, and Hong Kong stock market we show that our proposed method leads to improved portfolio allocation. PMID:23844016

  5. Directional variance adjustment: bias reduction in covariance matrices based on factor analysis with an application to portfolio optimization.

    PubMed

    Bartz, Daniel; Hatrick, Kerr; Hesse, Christian W; Müller, Klaus-Robert; Lemm, Steven

    2013-01-01

    Robust and reliable covariance estimates play a decisive role in financial and many other applications. An important class of estimators is based on factor models. Here, we show by extensive Monte Carlo simulations that covariance matrices derived from the statistical Factor Analysis model exhibit a systematic error, which is similar to the well-known systematic error of the spectrum of the sample covariance matrix. Moreover, we introduce the Directional Variance Adjustment (DVA) algorithm, which diminishes the systematic error. In a thorough empirical study for the US, European, and Hong Kong stock market we show that our proposed method leads to improved portfolio allocation.

  6. Factors affecting the placement or replacement of direct restorations in a dental school

    PubMed Central

    Silvani, Samara; Trivelato, Roberta Ferreira; Nogueira, Ruchele Dias; Gonçalves, Luciano de Souza; Geraldo-Martins, Vinícius Rangel

    2014-01-01

    Context: The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future. Purpose: The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University – Brazil. Materials and Methods: This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05). Results: The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1st-time placements, while 39.55% were replacements. For 1st-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05). Conclusions: The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite. PMID:24808696

  7. Sensitivity of scattering and absorbing aerosol direct radiative forcing to physical climate factors

    NASA Astrophysics Data System (ADS)

    Ocko, Ilissa B.; Ramaswamy, V.; Ginoux, Paul; Ming, Yi; Horowitz, Larry W.

    2012-10-01

    The direct radiative forcing of the climate system includes effects due to scattering and absorbing aerosols. This study explores how important physical climate characteristics contribute to the magnitudes of the direct radiative forcings (DRF) from anthropogenic sulfate, black carbon, and organic carbon. For this purpose, we employ the GFDL CM2.1 global climate model, which has reasonable aerosol concentrations and reconstruction of twentieth-century climate change. Sulfate and carbonaceous aerosols constitute the most important anthropogenic aerosol perturbations to the climate system and provide striking contrasts between primarily scattering (sulfate and organic carbon) and primarily absorbing (black carbon) species. The quantitative roles of cloud coverage, surface albedo, and relative humidity in governing the sign and magnitude of all-sky top-of-atmosphere (TOA) forcings are examined. Clouds reduce the global mean sulfate TOA DRF by almost 50%, reduce the global mean organic carbon TOA DRF by more than 30%, and increase the global mean black carbon TOA DRF by almost 80%. Sulfate forcing is increased by over 50% as a result of hygroscopic growth, while high-albedo surfaces are found to have only a minor (less than 10%) impact on all global mean forcings. Although the radiative forcing magnitudes are subject to uncertainties in the state of mixing of the aerosol species, it is clear that fundamental physical climate characteristics play a large role in governing aerosol direct radiative forcing magnitudes.

  8. Imaging analysis of nuclear antiviral factors through direct detection of incoming adenovirus genome complexes.

    PubMed

    Komatsu, Tetsuro; Will, Hans; Nagata, Kyosuke; Wodrich, Harald

    2016-04-22

    Recent studies involving several viral systems have highlighted the importance of cellular intrinsic defense mechanisms through nuclear antiviral proteins that restrict viral propagation. These factors include among others components of PML nuclear bodies, the nuclear DNA sensor IFI16, and a potential restriction factor PHF13/SPOC1. For several nuclear replicating DNA viruses, it was shown that these factors sense and target viral genomes immediately upon nuclear import. In contrast to the anticipated view, we recently found that incoming adenoviral genomes are not targeted by PML nuclear bodies. Here we further explored cellular responses against adenoviral infection by focusing on specific conditions as well as additional nuclear antiviral factors. In line with our previous findings, we show that neither interferon treatment nor the use of specific isoforms of PML nuclear body components results in co-localization between incoming adenoviral genomes and the subnuclear domains. Furthermore, our imaging analyses indicated that neither IFI16 nor PHF13/SPOC1 are likely to target incoming adenoviral genomes. Thus our findings suggest that incoming adenoviral genomes may be able to escape from a large repertoire of nuclear antiviral mechanisms, providing a rationale for the efficient initiation of lytic replication cycle.

  9. Using biologic predictive factors to direct therapy of diffuse large B-cell lymphoma

    PubMed Central

    Grant, Cliona; Wilson, Wyndham H.

    2013-01-01

    While diffuse large B-cell lymphoma (DLBCL) was once considered to be a single disease entity, recent biological insights have demonstrated that it can be divided up into at least three molecular subtypes. Gene expression profiling has revealed that DLBCL consists of a germinal center B-cell like subtype (GCB), an activated B-cell like subtype (ABC) and a primary mediastinal B-cell lymphoma subtype (PMBL). These three entities arise from different stages of B-cell differentiation and are characterized by distinct mechanisms of oncogenic activation. In GCB DLBCL, the BCL6 transcription factor may play an important role in tumor survival and treatment resistance and strategies that target this are under investigation. ABC DLBCL is characterized by high expression of target genes of the nuclear factor kappa B (NF-κB)/Rel family of transcription factors and strategies that target NF-κB are in clinical trials. PMBL is a distinct clinicopathologic entity that shares many molecular features with nodular sclerosis Hodgkin lymphoma (HL) and may benefit from dose intensity approaches and inhibition of the Janus kinases. Other biologic predictive factors such as MYC and BCL2 may be overexpressed in both the GCB and ABC subtypes and strategies that target these complexes are also being tested. PMID:23610613

  10. Peer Relationship Problems of Children with AD/HD: Risk Factors and New Directions in Interventions

    ERIC Educational Resources Information Center

    Ozdemir, Selda

    2009-01-01

    This review integrates and evaluates research conducted on possible contributing factors to peer relationship problems of children with attention deficit/hyperactivity disorder (AD/HD). Substantial evidence suggests that children with AD/HD have serious problems in multiple aspects of their relationships with peers. Difficulties resulting from…

  11. Influence of Parenting Factors on Childhood Social Anxiety: Direct Observation of Parental Warmth and Control

    ERIC Educational Resources Information Center

    Rork, Kristine E.; Morris, Tracy L.

    2009-01-01

    The purpose of the present study is to determine the association of parenting behaviors and social anxiety in children. Three parental factors--including parental socialization, control, and warmth--were investigated in a sample of 31 two-parent families. Rather than solely relying upon retrospective questionnaires, this study incorporated direct…

  12. The Direct and Indirect Effects of Environmental Factors on Nurturing Intellectual Giftedness

    ERIC Educational Resources Information Center

    Al-Shabatat, Ahmad Mohammad; Abbas, Merza; Ismail, Hairul Nizam

    2011-01-01

    Many people believe that environmental factors promote giftedness and invest in many programs to adopt gifted students providing them with challenging activities. Intellectual giftedness is founded on fluid intelligence and extends to more specific abilities through the growth and inputs from the environment. Acknowledging the roles played by the…

  13. The Direct and Indirect Effects of Environmental Factors on Nurturing Intellectual Giftedness

    ERIC Educational Resources Information Center

    Al-Shabatat, Ahmad Mohammad; Abbas, Merza; Ismail, Hairul Nizam

    2009-01-01

    Many people believe that environmental factors promote giftedness and invest in many programs to adopt gifted students providing them with challenging activities. Intellectual giftedness is founded on fluid intelligence and extends to more specific abilities through the growth and inputs from the environment. Acknowledging the roles played by the…

  14. Peer Relationship Problems of Children with AD/HD: Risk Factors and New Directions in Interventions

    ERIC Educational Resources Information Center

    Ozdemir, Selda

    2009-01-01

    This review integrates and evaluates research conducted on possible contributing factors to peer relationship problems of children with attention deficit/hyperactivity disorder (AD/HD). Substantial evidence suggests that children with AD/HD have serious problems in multiple aspects of their relationships with peers. Difficulties resulting from…

  15. Influence of Parenting Factors on Childhood Social Anxiety: Direct Observation of Parental Warmth and Control

    ERIC Educational Resources Information Center

    Rork, Kristine E.; Morris, Tracy L.

    2009-01-01

    The purpose of the present study is to determine the association of parenting behaviors and social anxiety in children. Three parental factors--including parental socialization, control, and warmth--were investigated in a sample of 31 two-parent families. Rather than solely relying upon retrospective questionnaires, this study incorporated direct…

  16. Is Low Vitamin D Status A Risk Factor For Food Allergy? Current Evidence And Future Directions.

    PubMed

    Molloy, John; Ponsonby, Anne-Louise; Allen, Katrina J; Tang, Mimi L K; Collier, Fiona M; Ward, Alister C; Koplin, Jennifer; Vuillermin, Peter

    2015-01-01

    Studies from several countries have reported an association between latitudes further from the equator and proxy markers of food allergy prevalence. As latitudes further from the equator are associated with lower sun exposure and vitamin D status (VDS), it has been proposed that low VDS may be a risk factor for food allergy. A range of basic science evidence supports the biological plausibility of this hypothesis; and recent work has identified a cross sectional association between low VDS and challenge proven food allergy in infants. Overall, however, the evidence regarding the relationship between VDS and food allergy remains controversial and the limited longitudinal data are discouraging. In this review we consider the evidence for and against low VDS as a risk factor for food allergy and discuss the possibility that other factors (including genetic variables) may contribute to the inconsistent nature of the available observational evidence. We then discuss whether genetic and/or environmental factors may modify the potential influence of VDS on food allergy risk. Finally, we argue that given the rising burden of food allergy, the balance of available evidence regarding the potential relevance of VDS to this phenomenon, and the inherent limitations of the existing observational data, there is a compelling case for conducting randomised clinical trials of vitamin D supplementation for the prevention of food allergy during early life.

  17. Receptor Signaling Directs Global Recruitment of Pre-existing Transcription Factors to Inducible Elements

    PubMed Central

    Cockerill, Peter N.

    2016-01-01

    Gene expression programs are largely regulated by the tissue-specific expression of lineage-defining transcription factors or by the inducible expression of transcription factors in response to specific stimuli. Here I will review our own work over the last 20 years to show how specific activation signals also lead to the wide-spread re-distribution of pre-existing constitutive transcription factors to sites undergoing chromatin reorganization. I will summarize studies showing that activation of kinase signaling pathways creates open chromatin regions that recruit pre-existing factors which were previously unable to bind to closed chromatin. As models I will draw upon genes activated or primed by receptor signaling in memory T cells, and genes activated by cytokine receptor mutations in acute myeloid leukemia. I also summarize a hit-and-run model of stable epigenetic reprograming in memory T cells, mediated by transient Activator Protein 1 (AP-1) binding, which enables the accelerated activation of inducible enhancers. PMID:28018147

  18. Synergistic Effects of Vascular Endothelial Growth Factor on Bone Morphogenetic Proteins Induced Bone Formation In Vivo: Influencing Factors and Future Research Directions

    PubMed Central

    Li, Bo; Wang, Hai; Qiu, Guixing; Su, Xinlin

    2016-01-01

    Vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMPs), as key mediators in angiogenesis and osteogenesis, are used in a combined delivery manner as a novel strategy in bone tissue engineering. VEGF has the potential to enhance BMPs induced bone formation. Both gene delivery and material-based delivery systems were incorporated in previous studies to investigate the synergistic effects of VEGF and BMPs. However, their results were controversial due to variation of methods incorporated in different studies. Factors influencing the synergistic effects of VEGF on BMPs induced bone formation were identified and analyzed in this review to reduce confusion on this issue. The potential mechanisms and directions of future studies were also proposed here. Further investigating mechanisms of the synergistic effects and optimizing these influencing factors will help to generate more effective bone regeneration. PMID:28070506

  19. Clinical genetic testing for male factor infertility: current applications and future directions.

    PubMed

    Hotaling, J; Carrell, D T

    2014-05-01

    Spermatogenesis involves the aggregated action of up to 2300 genes, any of which, could, potentially, provide targets for diagnostic tests of male factor infertility. Contrary to the previously proposed common variant hypothesis for common diseases such as male infertility, genome-wide association studies and targeted gene sequencing in cohorts of infertile men have identified only a few gene polymorphisms that are associated with male infertility. Unfortunately, the search for genetic variants associated with male infertility is further hampered by the lack of viable animal models of human spermatogenesis, difficulty in robustly phenotyping infertile men and the complexity of pedigree studies in male factor infertility. In this review, we describe basic genetic principles involved in understanding the genetic basis of male infertility and examine the utility and proper clinical use of the proven genetic assays of male factor infertility, specifically Y chromosome microdeletions, chromosomal translocations, karyotype, cystic fibrosis transmembrane conductance regulator mutation analysis and sperm genetic tests. Unfortunately, these tests are only able to diagnose the cause of about 20% of male factor infertility. The remainder of the review will be devoted to examining novel tests and diagnostic tools that have the potential to explain the other 80% of male factor infertility that is currently classified as idiopathic. Those tests include epigenetic analysis of the spermatozoa and the evaluation of rare genetic variants and copy number variations in patients. Success in advancing to the implementation of such areas is not only dependent on technological advances in the laboratory, but also improved phenotyping in the clinic. © 2014 American Society of Andrology and European Academy of Andrology.

  20. Imaging analysis of nuclear antiviral factors through direct detection of incoming adenovirus genome complexes

    SciTech Connect

    Komatsu, Tetsuro; Will, Hans; Nagata, Kyosuke; Wodrich, Harald

    2016-04-22

    Recent studies involving several viral systems have highlighted the importance of cellular intrinsic defense mechanisms through nuclear antiviral proteins that restrict viral propagation. These factors include among others components of PML nuclear bodies, the nuclear DNA sensor IFI16, and a potential restriction factor PHF13/SPOC1. For several nuclear replicating DNA viruses, it was shown that these factors sense and target viral genomes immediately upon nuclear import. In contrast to the anticipated view, we recently found that incoming adenoviral genomes are not targeted by PML nuclear bodies. Here we further explored cellular responses against adenoviral infection by focusing on specific conditions as well as additional nuclear antiviral factors. In line with our previous findings, we show that neither interferon treatment nor the use of specific isoforms of PML nuclear body components results in co-localization between incoming adenoviral genomes and the subnuclear domains. Furthermore, our imaging analyses indicated that neither IFI16 nor PHF13/SPOC1 are likely to target incoming adenoviral genomes. Thus our findings suggest that incoming adenoviral genomes may be able to escape from a large repertoire of nuclear antiviral mechanisms, providing a rationale for the efficient initiation of lytic replication cycle. - Highlights: • Host nuclear antiviral factors were analyzed upon adenovirus genome delivery. • Interferon treatments fail to permit PML nuclear bodies to target adenoviral genomes. • Neither Sp100A nor B targets adenoviral genomes despite potentially opposite roles. • The nuclear DNA sensor IFI16 does not target incoming adenoviral genomes. • PHF13/SPOC1 targets neither incoming adenoviral genomes nor genome-bound protein VII.

  1. Direct evidence for tumor necrosis factor-induced mitochondrial reactive oxygen intermediates and their involvement in cytotoxicity.

    PubMed Central

    Goossens, V; Grooten, J; De Vos, K; Fiers, W

    1995-01-01

    Tumor necrosis factor (TNF) is selectively cytotoxic to some types of tumor cells in vitro and exerts antitumor activity in vivo. Reactive oxygen intermediates (ROIs) have been implicated in the direct cytotoxic activity of TNF. By using confocal microscopy, flow cytometry, and the ROI-specific probe dihydrorhodamine 123, we directly demonstrate that intracellular ROIs are formed after TNF stimulation. These ROIs are observed exclusively under conditions where cells are sensitive to the cytotoxic activity of TNF, suggesting a direct link between both phenomena. ROI scavengers, such as butylated hydroxyanisole, effectively blocked the formation of free radicals and arrested the cytotoxic response, confirming that the observed ROIs are cytocidal. The mitochondrial glutathione system scavenges the major part of the produced ROIs, an activity that could be blocked by diethyl maleate; under these conditions, TNF-induced ROIs detectable by dihydrorhodamine 123 oxidation were 5- to 20-fold higher. Images Fig. 1 Fig. 4 PMID:7667254

  2. Bone marrow stromal cell paracrine factors direct osteo/odontogenic differentiation of dental pulp cells.

    PubMed

    Al-Sharabi, Niyaz; Xue, Ying; Fujio, Masahito; Ueda, Minoru; Gjerde, Cecilie; Mustafa, Kamal; Fristad, Inge

    2014-11-01

    Growth factors play an important role in osteo/odontogenic differentiation of human dental pulp cells (hDPCs). The aim of this in vitro study was to compare the biological effects of recombinant human growth differentiation factor 5 (rhGDF-5) alone and a cocktail of soluble growth factors (conditioned medium) released from human bone marrow mesenchymal stem cells (hBMMSCs) on the morphology, proliferation and osteo/odontogenic differentiation potential of hDPCs. Passage 4 hDPCs were harvested for culture in four different media: (a) DMEM with 10% FBS, (b) odontogenic induction medium (OM), (c) OM plus 500 ng/mL rhGDF-5, and (d) OM plus conditioned medium (CM). Morphological changes at 48 and 120 h were determined by crystal violet staining. The proliferation rates at 3, 24, 48, and 120 h were assayed by MTT. Using real-time reverse transcription-polymerase chain reaction (RT-PCR), the mRNA levels of dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), collagen type I (Col 1), Runt-related transcription factor 2 (Cbfa1/Runx2), alkaline phosphatase (ALP), osteocalcin (OC), β3 tubulin (TUBB3), glial cell-derived neurotrophic factor (GDNF), angiopoietin-1 (Ang1), and vascular endothelial growth factor A (VEGFA), were determined at 2, 5, and 9 days. Protein expression of dental sialoprotein (DSP), DMP1, OC, and TUBB3 was recorded at 5 days, using western blot and immunocytochemistry. The effect of the different culture media on mineralization was determined by ALP staining at day 5 and Alizarin red S staining at days 7 and 14. In response to the different culture media, the shape of the hDPCs varied from spindled to polygonal and cuboidal. CM inhibited the cellular proliferation rate, while rhGDF-5 had no effect at early time points, but promoted cellular proliferation at 120 h of culture. In the CM group, the mRNA levels of Cbfa1/Runx2, Col 1, ALP, VEGFA, Ang1, and TUBB3 decreased and the levels of GDNF and OC increased. The mRNA levels of DSPP

  3. Qualitative ergonomics/human factors research in health care: Current state and future directions.

    PubMed

    Valdez, Rupa Sheth; McGuire, Kerry Margaret; Rivera, A Joy

    2017-07-01

    The objective of this systematic review was to understand the current state of Ergonomics/Human Factors (E/HF) qualitative research in health care and to draw implications for future efforts. This systematic review identified 98 qualitative research papers published between January 2005 and August 2015 in the seven journals endorsed by the International Ergonomics Association with an impact factor over 1.0. The majority of the studies were conducted in hospitals and outpatient clinics, were focused on the work of formal health care professionals, and were classified as cognitive or organizational ergonomics. Interviews, focus groups, and observations were the most prevalent forms of data collection. Triangulation and data archiving were the dominant approaches to ensuring rigor. Few studies employed a formal approach to qualitative inquiry. Significant opportunities remain to enhance the use of qualitative research to advance systems thinking within health care. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Vaccine-Mediated Immunotherapy Directed Against a Transcription Factor Driving the Metastatic Process

    PubMed Central

    Ardiani, Andressa; Gameiro, Sofia R.; Palena, Claudia; Hamilton, Duane; Kwilas, Anna; King, Thomas H.; Schlom, Jeffrey; Hodge, James W.

    2015-01-01

    Numerous reports have now demonstrated that the epithelial-to-mesenchymal transition (EMT) process is involved in solid tumor progression, metastasis, and drug resistance. Several transcription factors have been implicated as drivers of EMT and metastatic progression, including Twist. Overexpression of Twist has been shown to be associated with poor prognosis and drug resistance for many carcinomas and other tumor types. The role of Twist in experimental cancer metastases has been principally studied in the 4T1 mammary tumor model, where silencing of Twist in vitro has been shown to greatly reduce in-vivo metastatic spread. Transcription factors such as Twist are generally believed to be “undruggable” due to their nuclear location and lack of a specific groove for tight binding of a small molecule inhibitor. An alternative approach to drug therapy targeting transcription factors driving the metastatic process is T-cell–mediated immunotherapy. A therapeutic vaccine platform that has been previously characterized consists of heat-killed recombinant Saccharomyces cerevisiae (yeast) capable of expressing tumor-associated antigen protein. We report here the construction and characterization of a recombinant yeast expressing the entire Twist protein, which is capable of inducing both CD8+ and CD4+ Twist-specific T-cell responses in vivo. Vaccination of mice reduced the size of primary transplanted 4T1 tumors and had an even greater anti-tumor effect on lung metastases of the same mice, which was dependent on Twist-specific CD8+ T cells. These studies provide the rationale for vaccine-induced T-cell–mediated therapy of transcription factors involved in driving the metastatic process. PMID:24520078

  5. Direct calibration in megavoltage photon beams using Monte Carlo conversion factor: validation and clinical implications.

    PubMed

    Wright, Tracy; Lye, Jessica E; Ramanathan, Ganesan; Harty, Peter D; Oliver, Chris; Webb, David V; Butler, Duncan J

    2015-01-21

    The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has established a method for ionisation chamber calibrations using megavoltage photon reference beams. The new method will reduce the calibration uncertainty compared to a (60)Co calibration combined with the TRS-398 energy correction factor. The calibration method employs a graphite calorimeter and a Monte Carlo (MC) conversion factor to convert the absolute dose to graphite to absorbed dose to water. EGSnrc is used to model the linac head and doses in the calorimeter and water phantom. The linac model is validated by comparing measured and modelled PDDs and profiles. The relative standard uncertainties in the calibration factors at the ARPANSA beam qualities were found to be 0.47% at 6 MV, 0.51% at 10 MV and 0.46% for the 18 MV beam. A comparison with the Bureau International des Poids et Mesures (BIPM) as part of the key comparison BIPM.RI(I)-K6 gave results of 0.9965(55), 0.9924(60) and 0.9932(59) for the 6, 10 and 18 MV beams, respectively, with all beams within 1σ of the participant average. The measured kQ values for an NE2571 Farmer chamber were found to be lower than those in TRS-398 but are consistent with published measured and modelled values. Users can expect a shift in the calibration factor at user energies of an NE2571 chamber between 0.4-1.1% across the range of calibration energies compared to the current calibration method.

  6. Transcription factor EGR1 directs tendon differentiation and promotes tendon repair

    PubMed Central

    Guerquin, Marie-Justine; Charvet, Benjamin; Nourissat, Geoffroy; Havis, Emmanuelle; Ronsin, Olivier; Bonnin, Marie-Ange; Ruggiu, Mathilde; Olivera-Martinez, Isabel; Robert, Nicolas; Lu, Yinhui; Kadler, Karl E.; Baumberger, Tristan; Doursounian, Levon; Berenbaum, Francis; Duprez, Delphine

    2013-01-01

    Tendon formation and repair rely on specific combinations of transcription factors, growth factors, and mechanical parameters that regulate the production and spatial organization of type I collagen. Here, we investigated the function of the zinc finger transcription factor EGR1 in tendon formation, healing, and repair using rodent animal models and mesenchymal stem cells (MSCs). Adult tendons of Egr1–/– mice displayed a deficiency in the expression of tendon genes, including Scx, Col1a1, and Col1a2, and were mechanically weaker compared with their WT littermates. EGR1 was recruited to the Col1a1 and Col2a1 promoters in postnatal mouse tendons in vivo. Egr1 was required for the normal gene response following tendon injury in a mouse model of Achilles tendon healing. Forced Egr1 expression programmed MSCs toward the tendon lineage and promoted the formation of in vitro–engineered tendons from MSCs. The application of EGR1-producing MSCs increased the formation of tendon-like tissues in a rat model of Achilles tendon injury. We provide evidence that the ability of EGR1 to promote tendon differentiation is partially mediated by TGF-β2. This study demonstrates EGR1 involvement in adult tendon formation, healing, and repair and identifies Egr1 as a putative target in tendon repair strategies. PMID:23863709

  7. Sequences promoting the transcription of the human XA gene overlapping P450c21A correctly predict the presence of a novel, adrenal-specific, truncated form of tenascin-X

    SciTech Connect

    Tee, Meng Kian; Thomson, A.A.; Bristow, J.; Miller, W.L.

    1995-07-20

    A compact region in the human class III major histocompatibility locus contains the human genes for the fourth component of human complement (C4) and steroid 21-hydroxylase (P450c21) in one transcriptional orientation, while the gene for the extracellular matrix protein tenascin-X (TN-X) overlaps the last exon of P450c21 on the opposite strand of DNA in the opposite transcriptional orientation. This complex locus is duplicated into A and B loci, so that the organization is 5{prime}-C4A-21A-XA-C4B-21B-XB-3{prime}. Although this duplication event truncated the 65-kb X(B) gene to a 4.5-kb XA gene, the XA gene is transcriptionally active in the adrenal cortex. To examine the basis of the tissue-specific expression of XA and C4B, we cloned the 1763-bp region that lies between the cap sites for XA and C4B and analyzed its promoter activity in both the XA and the C4 orientations. Powerful, liver-specific sequences lie within the first 75 to 138 bp from the C4B cap site, and weaker elements lie within 128 bp of the XA cap site that function in both liver and adrenal cells. Because these 128 bp upstream from the XA cap site are perfectly preserved in the XB gene encoding TN-X, we sought to determine whether a transcript similar to XA arises within the SB gene. RNase protection assays, cDNA cloning, and RT/PCR show that adrenal cells contain a novel transcript, termed short XB (XB-S), which has the same open reading frame as TN-X. Cell-free translation and immunoblotting show that this transcript encodes a novel 74-kDa XB-S protein that is identical to the carboxy-terminal 673 residues of TN-X. Because this protein consists solely of fibronectin type III repeats and a fibrinogen-like domain, it appears to correspond to an evolutionary precursor of the tenascin family of extracellular matrix proteins. 40 refs., 6 figs.

  8. Site-directed mutagenesis and saturation mutagenesis for the functional study of transcription factors involved in plant secondary metabolite biosynthesis.

    PubMed

    Pattanaik, Sitakanta; Werkman, Joshua R; Kong, Que; Yuan, Ling

    2010-01-01

    Regulation of gene expression is largely coordinated by a complex network of interactions between transcription factors (TFs), co-factors, and their cognate cis-regulatory elements in the genome. TFs are multidomain proteins that arise evolutionarily through protein domain shuffling. The modular nature of TFs has led to the idea that specific modules of TFs can be re-designed to regulate desired gene(s) through protein engineering. Utilization of designer TFs for the control of metabolic pathways has emerged as an effective approach for metabolic engineering. We are interested in engineering the basic helix-loop-helix (bHLH, Myc-type) transcription factors. Using site-directed and saturation mutagenesis, in combination with efficient and high-throughput screening systems, we have identified and characterized several amino acid residues critical for higher transactivation activity of a Myc-like bHLH transcription factor involved in anthocyanin biosynthetic pathway in plants. Site-directed and saturation mutagenesis should be generally applicable to engineering of all TFs.

  9. Self-evaluation as a moderating factor of strategy change in directed forgetting benefits.

    PubMed

    Sahakyan, Lili; Delaney, Peter F; Kelley, Colleen M

    2004-02-01

    In list method directed forgetting, instructing people to forget a studied word list usually results in better recall for a newly studied list. Sahakyan and Delaney (2003) have suggested that these benefits are due to a change in encoding strategy that occurs between the study of the first list and the study of the second list. To investigate what might mediate such strategy change decisions, in two experiments we induced both forget and remember participants to evaluate their memory performance on the two lists. In Experiment 1, they were asked to explicitly recall the items from the first list before studying the second list. In Experiment 2, after the study of the first list, the participants provided a rapid aggregate judgment of learning. Evaluation eliminated the differences between the forget and remember groups for the second list in both experiments, because the remember group achieved recall levels comparable to those for the forget group. The role of performance evaluation in mediating directed forgetting benefits is discussed.

  10. Factor analysis as a tool for spectral line component separation 21cm emission in the direction of L1780

    NASA Technical Reports Server (NTRS)

    Toth, L. V.; Mattila, K.; Haikala, L.; Balazs, L. G.

    1992-01-01

    The spectra of the 21cm HI radiation from the direction of L1780, a small high-galactic latitude dark/molecular cloud, were analyzed by multivariate methods. Factor analysis was performed on HI (21cm) spectra in order to separate the different components responsible for the spectral features. The rotated, orthogonal factors explain the spectra as a sum of radiation from the background (an extended HI emission layer), and from the L1780 dark cloud. The coefficients of the cloud-indicator factors were used to locate the HI 'halo' of the molecular cloud. Our statistically derived 'background' and 'cloud' spectral profiles, as well as the spatial distribution of the HI halo emission distribution were compared to the results of a previous study which used conventional methods analyzing nearly the same data set.

  11. The Function of the MEF2 Family of Transcription Factors in Cardiac Development, Cardiogenomics, and Direct Reprogramming

    PubMed Central

    Desjardins, Cody A.; Naya, Francisco J.

    2016-01-01

    Proper formation of the mammalian heart requires precise spatiotemporal transcriptional regulation of gene programs in cardiomyocytes. Sophisticated regulatory networks have evolved to not only integrate the activities of distinct transcription factors to control tissue-specific gene programs but also, in many instances, to incorporate multiple members within these transcription factor families to ensure accuracy and specificity in the system. Unsurprisingly, perturbations in this elaborate transcriptional circuitry can lead to severe cardiac abnormalities. Myocyte enhancer factor–2 (MEF2) transcription factor belongs to the evolutionarily conserved cardiac gene regulatory network. Given its central role in muscle gene regulation and its evolutionary conservation, MEF2 is considered one of only a few core cardiac transcription factors. In addition to its firmly established role as a differentiation factor, MEF2 regulates wide variety of, sometimes antagonistic, cellular processes such as cell survival and death. Vertebrate genomes encode multiple MEF2 family members thereby expanding the transcriptional potential of this core transcription factor in the heart. This review highlights the requirement of the MEF2 family and their orthologs in cardiac development in diverse animal model systems. Furthermore, we describe the recently characterized role of MEF2 in direct reprogramming and genome-wide cardiomyocyte gene regulation. A thorough understanding of the regulatory functions of the MEF2 family in cardiac development and cardiogenomics is required in order to develop effective therapeutic strategies to repair the diseased heart. PMID:27630998

  12. Direct targets of the transcription factors ABA-Insensitive(ABI)4 and ABI5 reveal synergistic action by ABI4 and several bZIP ABA response factors.

    PubMed

    Reeves, Wendy M; Lynch, Tim J; Mobin, Raisa; Finkelstein, Ruth R

    2011-03-01

    The plant hormone abscisic acid (ABA) is a key regulator of seed development. In addition to promoting seed maturation, ABA inhibits seed germination and seedling growth. Many components involved in ABA response have been identified, including the transcription factors ABA insensitive (ABI)4 and ABI5. The genes encoding these factors are expressed predominantly in developing and mature seeds, and are positive regulators of ABA mediated inhibition of seed germination and growth. The direct effects of ABI4 and ABI5 in ABA response remain largely undefined. To address this question, plants over-expressing ABI4 or ABI5 were used to allow identification of direct transcriptional targets. Ectopically expressed ABI4 and ABI5 conferred ABA-dependent induction of slightly over 100 genes in 11 day old plants. In addition to effector genes involved in seed maturation and reserve storage, several signaling proteins and transcription factors were identified as targets of ABI4 and/or ABI5. Although only 12% of the ABA- and ABI-dependent transcriptional targets were induced by both ABI factors in 11 day old plants, 40% of those normally expressed in seeds had reduced transcript levels in both abi4 and abi5 mutants. Surprisingly, many of the ABI4 transcriptional targets do not contain the previously characterized ABI4 binding motifs, the CE1 or S box, in their promoters, but some of these interact with ABI4 in electrophoretic mobility shift assays, suggesting that sequence recognition by ABI4 may be more flexible than known canonical sequences. Yeast one-hybrid assays demonstrated synergistic action of ABI4 with ABI5 or related bZIP factors in regulating these promoters, and mutant analyses showed that ABI4 and these bZIPs share some functions in plants.

  13. Directional reflectance factors for monitoring spatial changes in soil surface structure and soil organic matter erosion in agricultural systems

    NASA Astrophysics Data System (ADS)

    Croft, H.; Anderson, K.

    2012-04-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of soil organic matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness (SSR), indicating that a soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Accurate, spatially-continuous measurements of SSR are therefore needed at a variety of spatial and temporal scales to understand the spatial nature of SOM erosion and deposition. Remotely-sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Previous work has demonstrated the ability of directional reflectance factors to monitor soil crusting within a controlled laboratory experiment, due to changes in the levels of self-shadowing effects by soil aggregates. However, further research is needed to test this approach in situ, where other soil variables may affect measured reflectance factors and to investigate the use of directional reflectance factors for monitoring soil erosion processes. This experiment assesses the potential of using directional reflectance factors to monitor changes in SSR, aggregate stability and soil organic carbon (SOC) content for two agricultural conditions. Five soil plots representing tilled and seedbed soils were subjected to different durations of natural rainfall, producing a range of different levels of SSR. Directional reflectance factors were measured concomitantly with sampling for soil structural and biochemical tests at each soil plot. Soil samples were taken to measure aggregate stability (wet sieving), SOC (loss on ignition) and soil moisture (gravimetric method). SSM

  14. Human factors in environmental management: New directions from the Hanford Site

    SciTech Connect

    Wise, J.A.; Savage, S.F.

    1992-10-01

    Environmental management is the general term given to modern attempts to seek technological solutions to certain constrained environmental problems. it involves developing and applying new technologies that respond to changes in environmental policy. It does not eliminate the need for environmental ethics'' in society. Nor does it substitute for the fundamental changes in political and social structures that are needed for dealing with large-scale environmental issues. The scope of these issues can be illustrated by looking at the Hanford Site. Since 1943, the 560-square-mile Hanford Site in southeastern Washington state has been the production source of much of the nuclear weapons-grade radioactive materials for the United States. The legacy of 50 years of producing fissile materials has been an environmental cleanup problem of impressive proportions. In 1989, with the Cold War winding down, Secretary of Energy James Watkins established a new vision for Hanford as the flagship for waste management research.'' As plans and preparations for cleanup work proceed at the Hanford Site and around the world, the need for well-orchestrated environmental management methodologies has become increasingly apparent. In 1990, a Human Factors Engineering Group was established in the Technology Planning and Analysis Center at PNL to provide appropriate support for the Laboratory's research efforts. At an ever-increasing rate, these research efforts require integrating human performance into complex environmental technology systems. The endeavor of responding to the Laboratory's research needs has provided innovative opportunities for the application of the concept of Human Factors. Discussed are some of the major applications of Human Factors to environmental management.

  15. Covalent growth factor tethering to direct neural stem cell differentiation and self-organization.

    PubMed

    Ham, Trevor R; Farrag, Mahmoud; Leipzig, Nic D

    2017-04-15

    Tethered growth factors offer exciting new possibilities for guiding stem cell behavior. However, many of the current methods present substantial drawbacks which can limit their application and confound results. In this work, we developed a new method for the site-specific covalent immobilization of azide-tagged growth factors and investigated its utility in a model system for guiding neural stem cell (NSC) behavior. An engineered interferon-γ (IFN-γ) fusion protein was tagged with an N-terminal azide group, and immobilized to two different dibenzocyclooctyne-functionalized biomimetic polysaccharides (chitosan and hyaluronan). We successfully immobilized azide-tagged IFN-γ under a wide variety of reaction conditions, both in solution and to bulk hydrogels. To understand the interplay between surface chemistry and protein immobilization, we cultured primary rat NSCs on both materials and showed pronounced biological effects. Expectedly, immobilized IFN-γ increased neuronal differentiation on both materials. Expression of other lineage markers varied depending on the material, suggesting that the interplay of surface chemistry and protein immobilization plays a large role in nuanced cell behavior. We also investigated the bioactivity of immobilized IFN-γ in a 3D environment in vivo and found that it sparked the robust formation of neural tube-like structures from encapsulated NSCs. These findings support a wide range of potential uses for this approach and provide further evidence that adult NSCs are capable of self-organization when exposed to the proper microenvironment. For stem cells to be used effectively in regenerative medicine applications, they must be provided with the appropriate cues and microenvironment so that they integrate with existing tissue. This study explores a new method for guiding stem cell behavior: covalent growth factor tethering. We found that adding an N-terminal azide-tag to interferon-γ enabled stable and robust Cu-free 'click

  16. Adipose Expression of Tumor Necrosis Factor-α: Direct Role in Obesity-Linked Insulin Resistance

    NASA Astrophysics Data System (ADS)

    Hotamisligil, Gokhan S.; Shargill, Narinder S.; Spiegelman, Bruce M.

    1993-01-01

    Tumor necrosis factor-α (TNF-α) has been shown to have certain catabolic effects on fat cells and whole animals. An induction of TNF-α messenger RNA expression was observed in adipose tissue from four different rodent models of obesity and diabetes. TNF-α protein was also elevated locally and systemically. Neutralization of TNF-α in obese fa/fa rats caused a significant increase in the peripheral uptake of glucose in response to insulin. These results indicate a role for TNF-α in obesity and particularly in the insulin resistance and diabetes that often accompany obesity.

  17. Factors related to self-directed learning readiness of students in health professional programs: A scoping review.

    PubMed

    Slater, Craig E; Cusick, Anne

    2017-05-01

    Academic and professional drivers have stimulated interest in self-directed learning of students in pre-certification health professional programs. Particular attention has focussed on factors which may influence a students' readiness for self-directed learning. A five stage structured scoping review of published literature was conducted to identify measures of self-directed learning readiness used with students in pre-certification health professional programs and those factors that have been investigated as potential determinants. Relevant articles were identified in six databases using key search terms and a search strategy. Two independent reviewers used criteria to cull irrelevant sources. Articles which met eligibility criteria were charted. The final analysis included 49 articles conducted in nursing, medicine, physiotherapy, pharmacy, occupational therapy and dentistry cohorts. Twenty-one potential determinants had been investigated with gender, year level, age program delivery and previous education level the most common. Self-directed learning readiness has been of interest globally, mostly in medicine and nursing, and studies have nearly exclusively used one of two instruments. There is nascent evidence that age, year level and previous education level may have positive influence. These factors have in common the passing of time and may in fact be proxy for more encompassing developmental or social constructs. Further research is needed particularly in the allied health professions where there is limited research in very few disciplines. Studies in interprofessional contexts may be an efficient approach to increasing the knowledge base. Further work is also warranted to determine appropriate use of the two instruments across the range of health disciplines. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Some ionospheric factors affecting the coverage of an HF/VHF direct broadcasting satellite service

    NASA Astrophysics Data System (ADS)

    Rush, C. M.; Stewart, F. G.; Pokempner, M.; Reasoner, R.

    1986-04-01

    A study has been undertaken to assess the effects of the ionosphere on the performance of a direct broadcasting satellite service operating in the high frequency (HF) band. Results relating to two issues of performance are presented: (1) determining under what conditions a frequency allocated to the broadcasting service can be expected to reach the surface of the earth from a satellite and (2) the loss of signal strength due to passage through the ionosphere. It was found that if high frequency broadcast services are to be provided on a worldwide basis using satellite platforms, the satellites need to be optimally configured for the intended service area. Also, a 3 dB loss of signal strength is expected due to ionospheric absorption.

  19. Factors that affect micro-tooling features created by direct printing approach

    NASA Astrophysics Data System (ADS)

    Kumbhani, Mayur N.

    Current market required faster pace production of smaller, better, and improved products in shorter amount of time. Traditional high-rate manufacturing process such as hot embossing, injection molding, compression molding, etc. use tooling to replicate feature on a products. Miniaturization of many product in the field of biomedical, electronics, optical, and microfluidic is occurring on a daily bases. There is a constant need to produce cheaper, and faster tooling, which can be utilize by existing manufacturing processes. Traditionally, in order to manufacture micron size tooling features processes such as micro-machining, Electrical Discharge Machining (EDM), etc. are utilized. Due to a higher difficulty to produce smaller size features, and longer production cycle time, various additive manufacturing approaches are proposed, e.g. selective laser sintering (SLS), inkjet printing (3DP), fused deposition modeling (FDM), etc. were proposed. Most of these approaches can produce net shaped products from different materials such as metal, ceramic, or polymers. Several attempts were made to produce tooling features using additive manufacturing approaches. Most of these produced tooling were not cost effective, and the life cycle of these tooling was reported short. In this research, a method to produce tooling features using direct printing approach, where highly filled feedstock was dispensed on a substrate. This research evaluated different natural binders, such as guar gum, xanthan gum, and sodium carboxymethyl cellulose (NaCMC) and their combinations were evaluated. The best binder combination was then use to evaluate effect of different metal (316L stainless steel (3 mum), 316 stainless steel (45 mum), and 304 stainless steel (45 mum)) particle size on feature quality. Finally, the effect of direct printing process variables such as dispensing tip internal diameter (500 mum, and 333 mum) at different printing speeds were evaluated.

  20. Direct transfer of hepatocyte growth factor gene into kidney suppresses cyclosporin A nephrotoxicity in rats.

    PubMed

    Yazawa, Koji; Isaka, Yoshitaka; Takahara, Shiro; Imai, Enyu; Ichimaru, Naotsugu; Shi, Yi; Namba, Yukiomi; Okuyama, Akihiko

    2004-04-01

    The clinical utility of cyclosporin A (CsA) has been limited by its nephrotoxicity, which is characterized by tubular atrophy, interstitial fibrosis and progressive renal impairment. Hepatocyte growth factor (HGF), which plays diverse roles in the regeneration of the kidney following acute renal failure, has been reported to protect against and salvage renal injury by acting as a renotropic and anti-fibrotic factor. Here, we investigated protective effects of HGF gene therapy on CsA-induced nephrotoxicity by using an electroporation-mediated gene transfer method. CsA was orally administered as a daily dose of 30 mg/kg in male Sprague-Dawley rats receiving a low sodium diet (0.03% sodium). Plasmid vector encoding HGF (200 micro g) was transferred into the kidney by electroporation. HGF gene transfer resulted in significant increases in plasma HGF levels. Morphological assessment revealed that HGF gene transfer reduced CsA-induced initial tubular injury and inhibited interstitial infiltration of ED-1-positive macrophages. In addition, northern blot analysis demonstrated that cortical mRNA levels of TGF-beta and type I collagen were suppressed in the HGF group. Finally, HGF gene transfer significantly reduced striped interstitial phenotypic alterations and fibrosis in CsA-treated rats, as assessed by alpha-smooth muscle actin expression and Masson's trichrome staining. These results suggest that HGF may prevent CsA-induced tubulointerstitial fibrosis, indicating that HGF gene transfer may provide a potential strategy for preventing renal fibrosis.

  1. Factors Affecting Patients' Perception On, and Adherence To, Anticoagulant Therapy: Anticipating the Role of Direct Oral Anticoagulants.

    PubMed

    Pandya, Ekta Y; Bajorek, Beata

    2017-04-01

    The role of the direct oral anticoagulants (DOACs) in practice has been given extensive consideration recently, albeit largely from the clinician's perspective. However, the effectiveness and safety of using anticoagulants is highly dependent on the patient's ability to manage and take these complex, high-risk medicines. This structured narrative review explores the published literature to identify the factors underpinning patients' non-adherence to anticoagulants in atrial fibrillation (AF), and subsequently contemplates to what extent the DOACs might overcome the known challenges with traditional warfarin therapy. This review comprised a two-tier search of various databases and search platforms (CINAHL, Cochrane, Current Contents Connect, EMBASE, MEDLINE Ovid, EBSCO, PubMed, Google, Google Scholar) to yield 47 articles reporting patients perspectives on, and patients adherence to, anticoagulant therapy. The findings from the literature were synthesised under five interacting dimensions of adherence: therapy-related factors, patient-related factors, condition-related factors, social-economic factors and health system factors. Factors negatively affecting patients' day-to-day lives (especially regular therapeutic drug monitoring, dose adjustments, dietary considerations) predominantly underpin a patient's reluctance to take warfarin therapy, leading to non-adherence. Other patient-related factors underpinning non-adherence include patients' perceptions and knowledge about the purpose of anticoagulation; understanding of the risks and benefits of therapy; socioeconomic status; and expectations of care from health professionals. In considering these findings, it is apparent that the DOACs may overcome some of the barriers to traditional warfarin therapy at least to an extent, particularly the need for regular monitoring, frequent dose adjustment and dietary considerations. However, their high cost, twice-daily dosing and gastrointestinal adverse effects may present

  2. Transcription Factor Networks Directing the Development, Function, and Evolution of Innate Lymphoid Effectors

    PubMed Central

    Kang, Joonsoo; Malhotra, Nidhi

    2015-01-01

    Mammalian lymphoid immunity is mediated by fast and slow responders to pathogens. Fast innate lymphocytes are active within hours after infections in mucosal tissues. Slow adaptive lymphocytes are conventional T and B cells with clonal antigen receptors that function days after pathogen exposure. A transcription factor (TF) regulatory network guiding early T cell development is at the core of effector function diversification in all innate lymphocytes, and the kinetics of immune responses is set by developmental programming. Operational units within the innate lymphoid system are not classified by the types of pathogen-sensing machineries but rather by discrete effector functions programmed by regulatory TF networks. Based on the evolutionary history of TFs of the regulatory networks, fast effectors likely arose earlier in the evolution of animals to fortify body barriers, and in mammals they often develop in fetal ontogeny prior to the establishment of fully competent adaptive immunity. PMID:25650177

  3. Autocrine epidermal growth factor signaling stimulates directionally persistent mammary epithelial cell migration

    SciTech Connect

    Maheshwari, Gargi; Wiley, H Steven ); Lauffenburger, Douglas A.

    2001-12-24

    Autocrine receptor/ligand signaling loops were first identified in tumor cells, where it was found that transformation of cells resulted in overexpression of certain growth factors leading to unregulated proliferation of the tumor cells (Sporn and Todaro, 1980). However, in the ensuing decades autocrine signaling has been found to operate in numerous physiological situations (Sporn and Roberts, 1992), including wound healing (Tokumaru et al., 2000), angiogenesis (Seghezzi et al., 1998), and tissue organization during development (Wasserman and Freeman, 1998) and reproductive cycles (Xie et al., 1997). Although it is becoming evident that autocrine loops play crucial roles in regulation of cell function within tissue contexts, it is unclear whether their effects on cell responses are different from the effects of the same ligand presented in exogenous or paracrine manner.

  4. Transcription factor networks directing the development, function, and evolution of innate lymphoid effectors.

    PubMed

    Kang, Joonsoo; Malhotra, Nidhi

    2015-01-01

    Mammalian lymphoid immunity is mediated by fast and slow responders to pathogens. Fast innate lymphocytes are active within hours after infections in mucosal tissues. Slow adaptive lymphocytes are conventional T and B cells with clonal antigen receptors that function days after pathogen exposure. A transcription factor (TF) regulatory network guiding early T cell development is at the core of effector function diversification in all innate lymphocytes, and the kinetics of immune responses is set by developmental programming. Operational units within the innate lymphoid system are not classified by the types of pathogen-sensing machineries but rather by discrete effector functions programmed by regulatory TF networks. Based on the evolutionary history of TFs of the regulatory networks, fast effectors likely arose earlier in the evolution of animals to fortify body barriers, and in mammals they often develop in fetal ontogeny prior to the establishment of fully competent adaptive immunity.

  5. Chrysanthemum transcription factor CmLBD1 direct lateral root formation in Arabidopsis thaliana

    PubMed Central

    Zhu, Lu; Zheng, Chen; Liu, Ruixia; Song, Aiping; Zhang, Zhaohe; Xin, Jingjing; Jiang, Jiafu; Chen, Sumei; Zhang, Fei; Fang, Weimin; Chen, Fadi

    2016-01-01

    The plant-specific LATERAL ORGAN BOUNDARIES DOMAIN (LBD) genes are important regulators of growth and development. Here, a chrysanthemum class I LBD transcription factor gene, designated CmLBD1, was isolated and its function verified. CmLBD1 was transcribed in both the root and stem, but not in the leaf. The gene responded to auxin and was shown to participate in the process of adventitious root primordium formation. Its heterologous expression in Arabidopsis thaliana increased the number of lateral roots formed. When provided with exogenous auxin, lateral root emergence was promoted. CmLBD1 expression also favored callus formation from A. thaliana root explants in the absence of exogenously supplied phytohormones. In planta, CmLBD1 probably acts as a positive regulator of the response to auxin fluctuations and connects auxin signaling with lateral root formation. PMID:26819087

  6. Risk and protective factors for sexual aggression and dating violence: common themes and future directions.

    PubMed

    Thompson, Martie P

    2014-10-01

    The primary aims of this article are to expand on three themes from the conference articles on risk and protective factors for dating and sexual violence and to offer suggestions that can guide future research. The first theme is the co-occurrence of sexual and dating violence with other forms of violence and other campus health issues. A second topic is the value of prospective studies in revealing temporal patterns of victimization and perpetration. A third theme is the role of peer norms in violence among college students. Suggestions for translating these ideas into research and action are discussed and include the need for comprehensive prevention approaches, more longitudinal research spanning the years before, during, and after college, and the application of social media technology in our interventions strategies.

  7. Directed random walks and constraint programming reveal active pathways in hepatocyte growth factor signaling.

    PubMed

    Kittas, Aristotelis; Delobelle, Aurélien; Schmitt, Sabrina; Breuhahn, Kai; Guziolowski, Carito; Grabe, Niels

    2016-01-01

    An effective means to analyze mRNA expression data is to take advantage of established knowledge from pathway databases, using methods such as pathway-enrichment analyses. However, pathway databases are not case-specific and expression data could be used to infer gene-regulation patterns in the context of specific pathways. In addition, canonical pathways may not always describe the signaling mechanisms properly, because interactions can frequently occur between genes in different pathways. Relatively few methods have been proposed to date for generating and analyzing such networks, preserving the causality between gene interactions and reasoning over the qualitative logic of regulatory effects. We present an algorithm (MCWalk) integrated with a logic programming approach, to discover subgraphs in large-scale signaling networks by random walks in a fully automated pipeline. As an exemplary application, we uncover the signal transduction mechanisms in a gene interaction network describing hepatocyte growth factor-stimulated cell migration and proliferation from gene-expression measured with microarray and RT-qPCR using in-house perturbation experiments in a keratinocyte-fibroblast co-culture. The resulting subgraphs illustrate possible associations of hepatocyte growth factor receptor c-Met nodes, differentially expressed genes and cellular states. Using perturbation experiments and Answer Set programming, we are able to select those which are more consistent with the experimental data. We discover key regulator nodes by measuring the frequency with which they are traversed when connecting signaling between receptors and significantly regulated genes and predict their expression-shift consistently with the measured data. The Java implementation of MCWalk is publicly available under the MIT license at: https://bitbucket.org/akittas/biosubg. © 2015 FEBS.

  8. Phytochrome-interacting factors directly suppress MIR156 expression to enhance shade-avoidance syndrome in Arabidopsis.

    PubMed

    Xie, Yurong; Liu, Yang; Wang, Hai; Ma, Xiaojing; Wang, Baobao; Wu, Guangxia; Wang, Haiyang

    2017-08-24

    Plants have evolved a repertoire of strategies collectively termed the shade-avoidance syndrome to avoid shade from canopy and compete for light with their neighbors. However, the signaling mechanism governing the adaptive changes of adult plant architecture to shade is not well understood. Here, we show that in Arabidopsis, compared with the wild type, several PHYTOCHROME-INTERACTING FACTORS (PIFS) overexpressors all display constitutive shade-avoidance syndrome under normal high red to far-red light ratio conditions but are less sensitive to the simulated shade, whereas the MIR156 overexpressors exhibit an opposite phenotype. The simulated shade induces rapid accumulation of PIF proteins, reduced expression of multiple MIR156 genes, and concomitant elevated expression of the SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family genes. Moreover, in vivo and in vitro assays indicate that PIFs bind to the promoters of several MIR156 genes directly and repress their expression. Our results establish a direct functional link between the phytochrome-PIFs and miR156-SPL regulatory modules in mediating shade-avoidance syndrome.Plants employ developmental strategies to avoid shade and compete with neighbors for light. Here, Xie et al. show that phytochrome-interacting factors, which are regulated in a light-dependent manner, directly repress MIR156 genes and promote the expression of SPL genes to enhance shade-avoidance responses.

  9. Direct and Indirect Effects of Five Factor Personality and Gender on Depressive Symptoms Mediated by Perceived Stress.

    PubMed

    Kim, Song E; Kim, Han-Na; Cho, Juhee; Kwon, Min-Jung; Chang, Yoosoo; Ryu, Seungho; Shin, Hocheol; Kim, Hyung-Lae

    2016-01-01

    This study was designed to investigate associations among five factor personality traits, perceived stress, and depressive symptoms and to examine the roles of personality and perceived stress in the relationship between gender and depressive symptoms. The participants (N = 3,950) were part of a cohort study for health screening and examination at the Kangbuk Samsung Hospital. Personality was measured with the Revised NEO Personality Inventory (NEO-PI-R). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D). Perceived stress level was evaluated with a self-reported stress questionnaire developed for the Korea National Health and Nutrition Examination Survey. A higher degree of neuroticism and lower degrees of extraversion, agreeableness, and conscientiousness were significantly associated with greater perceived stress and depressive symptoms. Neuroticism and extraversion had significant direct and indirect effects (via stress as a mediator) on depressive symptoms in both genders. Agreeableness and conscientiousness had indirect effects on depression symptoms in both genders. Multiple mediation models were used to examine the mediational roles of each personality factor and perceived stress in the link between gender and depressive symptoms. Four of the personality factors (except openness) were significant mediators, along with stress, on the relationship between gender and depressive symptoms. Our findings suggest that the links between personality factors and depressive symptoms are mediated by perceived stress. As such, personality is an important factor to consider when examining the link between gender and depression.

  10. Direct and Indirect Effects of Five Factor Personality and Gender on Depressive Symptoms Mediated by Perceived Stress

    PubMed Central

    Kim, Song E.; Cho, Juhee; Kwon, Min-Jung; Chang, Yoosoo; Ryu, Seungho; Shin, Hocheol

    2016-01-01

    This study was designed to investigate associations among five factor personality traits, perceived stress, and depressive symptoms and to examine the roles of personality and perceived stress in the relationship between gender and depressive symptoms. The participants (N = 3,950) were part of a cohort study for health screening and examination at the Kangbuk Samsung Hospital. Personality was measured with the Revised NEO Personality Inventory (NEO-PI-R). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D). Perceived stress level was evaluated with a self-reported stress questionnaire developed for the Korea National Health and Nutrition Examination Survey. A higher degree of neuroticism and lower degrees of extraversion, agreeableness, and conscientiousness were significantly associated with greater perceived stress and depressive symptoms. Neuroticism and extraversion had significant direct and indirect effects (via stress as a mediator) on depressive symptoms in both genders. Agreeableness and conscientiousness had indirect effects on depression symptoms in both genders. Multiple mediation models were used to examine the mediational roles of each personality factor and perceived stress in the link between gender and depressive symptoms. Four of the personality factors (except openness) were significant mediators, along with stress, on the relationship between gender and depressive symptoms. Our findings suggest that the links between personality factors and depressive symptoms are mediated by perceived stress. As such, personality is an important factor to consider when examining the link between gender and depression. PMID:27120051