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Sample records for chemical inhibitors destabilize

  1. Chemical Stabilization and Electrochemical Destabilization of the Iron Keggin Ion in Water

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Omid; Falaise, Clement; Molina, Pedro I.; Hufschmid, Ryan D.; Campana, Charles F.; Noll, Bruce C.; Browning, Nigel D.; Nyman, May

    2016-10-18

    The iron Keggin ion is identified as a structural building block in both magnetite and ferrihydrite, two important iron oxide phases in nature and in technology. Discrete molecular forms of the iron Keggin ion that can be both manipulated in water and chemically converted to the related metal oxides are important for understanding growth mechanisms, in particular non-classical nucleation in which cluster building units are preserved in the aggregation and condensation processes. Here we describe two iron Keggin ion structures, formulated [Bi6FeO4Fe12O12(OH)12(CF3COO)10(H2O)2]3+ and [Bi6FeO4Fe12O12(OH)12(CF3COO)12]1+. Experimental and simulated X-ray scattering studies show indefinite stability of these clusters in water from pH 1-3. The tridecameric iron Keggin-ion core is protected from hydrolysis by a synergistic effect of the capping Bi3+-cations and the trifluoroacetate ligands that respectively bond to the iron and bridge to the bismuth. By introducing electrons to the aqueous solution of clusters, we achieve complete separation of bismuth from the cluster, and the iron Keggin ion rapidly converts to magnetite and/or ferrihydrite, depending on the mechanism of reduction. In this strategy, we take advantage of the easily accessible reduction potential and crystallization energy of bismuth. Reduction was executed in bulk by chemical means, by voltammetry, and by secondary effects of transmission electron microscopy imaging of solutions. Prior, we showed a less stable analogue of the iron Keggin cluster converted to ferrihydrite simply upon dissolution. The prior and currently studied clusters with a range of reactivity provide a chemical system to study molecular cluster metal oxide conversion processes in detail.

  2. Electrostatic transition state stabilization rather than reactant destabilization provides the chemical basis for efficient chorismate mutase catalysis.

    Science.gov (United States)

    Burschowsky, Daniel; van Eerde, André; Ökvist, Mats; Kienhöfer, Alexander; Kast, Peter; Hilvert, Donald; Krengel, Ute

    2014-12-09

    For more than half a century, transition state theory has provided a useful framework for understanding the origins of enzyme catalysis. As proposed by Pauling, enzymes accelerate chemical reactions by binding transition states tighter than substrates, thereby lowering the activation energy compared with that of the corresponding uncatalyzed process. This paradigm has been challenged for chorismate mutase (CM), a well-characterized metabolic enzyme that catalyzes the rearrangement of chorismate to prephenate. Calculations have predicted the decisive factor in CM catalysis to be ground state destabilization rather than transition state stabilization. Using X-ray crystallography, we show, in contrast, that a sluggish variant of Bacillus subtilis CM, in which a cationic active-site arginine was replaced by a neutral citrulline, is a poor catalyst even though it effectively preorganizes chorismate for the reaction. A series of high-resolution molecular snapshots of the reaction coordinate, including the apo enzyme, and complexes with substrate, transition state analog and product, demonstrate that an active site, which is only complementary in shape to a reactive substrate conformer, is insufficient for effective catalysis. Instead, as with other enzymes, electrostatic stabilization of the CM transition state appears to be crucial for achieving high reaction rates.

  3. The effect of chemical anti-inhibitors on fibrinolytic enzymes and inhibitors

    DEFF Research Database (Denmark)

    Sidelmann, Johannes Jakobsen; Jespersen, J; Kluft, C;

    1997-01-01

    Fibrinolytic enzyme inhibitors hamper the determination of the specific fibrinolytic serine protease activity. Reportedly, chemical anti-inhibitors eliminate the influence of fibrinolytic inhibitors, but it remains unclear to what extent they change the specific activity of fibrinolytic serine pr...

  4. A porphodimethene chemical inhibitor of uroporphyrinogen decarboxylase.

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    Kenneth W Yip

    Full Text Available Uroporphyrinogen decarboxylase (UROD catalyzes the conversion of uroporphyrinogen to coproporphyrinogen during heme biosynthesis. This enzyme was recently identified as a potential anticancer target; its inhibition leads to an increase in reactive oxygen species, likely mediated by the Fenton reaction, thereby decreasing cancer cell viability and working in cooperation with radiation and/or cisplatin. Because there is no known chemical UROD inhibitor suitable for use in translational studies, we aimed to design, synthesize, and characterize such a compound. Initial in silico-based design and docking analyses identified a potential porphyrin analogue that was subsequently synthesized. This species, a porphodimethene (named PI-16, was found to inhibit UROD in an enzymatic assay (IC50 = 9.9 µM, but did not affect porphobilinogen deaminase (at 62.5 µM, thereby exhibiting specificity. In cellular assays, PI-16 reduced the viability of FaDu and ME-180 cancer cells with half maximal effective concentrations of 22.7 µM and 26.9 µM, respectively, and only minimally affected normal oral epithelial (NOE cells. PI-16 also combined effectively with radiation and cisplatin, with potent synergy being observed in the case of cisplatin in FaDu cells (Chou-Talalay combination index <1. This work presents the first known synthetic UROD inhibitor, and sets the foundation for the design, synthesis, and characterization of higher affinity and more effective UROD inhibitors.

  5. Geometrical Destabilization of Inflation

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    Renaux-Petel, Sébastien; Turzyński, Krzysztof

    2016-09-01

    We show the existence of a general mechanism by which heavy scalar fields can be destabilized during inflation, relying on the fact that the curvature of the field space manifold can dominate the stabilizing force from the potential and destabilize inflationary trajectories. We describe a simple and rather universal setup in which higher-order operators suppressed by a large energy scale trigger this instability. This phenomenon can prematurely end inflation, thereby leading to important observational consequences and sometimes excluding models that would otherwise perfectly fit the data. More generally, it modifies the interpretation of cosmological constraints in terms of fundamental physics. We also explain how the geometrical destabilization can lead to powerful selection criteria on the field space curvature of inflationary models.

  6. Corrosion inhibitors: Correlation between chemical structure and efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Lukovits, I.; Koszto, T. [Hungarian Academy of Sciences (Hungary). Inst. of Chemistry

    1999-11-01

    Corrosion inhibition efficiencies of heterocyclic aromatic or partially saturated aromatic compounds (pyrimidines, benzothiazole derivatives, amino-acids containing an aromatic part, pyridines and quinolines) were correlated with quan chemical indices of the respective molecules. Inhibition efficiencies measured in acidic solutions containing 0.001 and 0.01 mol/L of the inhibitor, respectively, were collected. The quantum chemical calculations were done by using the simple Hueckel method. Comparison of inhibition efficiencies and the differences between energies of the highest occupied and the lowest unoccupied molecular orbitals {Delta} indicated that if {Delta} is lower than 1.3 (in beta units) then the compound will not be active, whereas if {Delta} > 1.3 beta, the compound may be efficient in 0.001 mole/L concentration. The critical value of {Delta} may be lower in solution with 0.01 mole/L inhibitor concentration. Although {Delta} alone is not sufficient to account for the variation in the experimental inhibition efficiencies, the present result indicates that compounds which may be easily excited will be inefficient inhibitors because they maybe altered or decomposed after the excitation takes place.

  7. Navigating the chemical space of dipeptidyl peptidase-4 inhibitors

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    Shoombuatong W

    2015-08-01

    Full Text Available Watshara Shoombuatong,1 Veda Prachayasittikul,1,2 Nuttapat Anuwongcharoen,1 Napat Songtawee,1 Teerawat Monnor,1 Supaluk Prachayasittikul,1 Virapong Prachayasittikul,2 Chanin Nantasenamat1,2 1Center of Data Mining and Biomedical Informatics, 2Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand Abstract: This study represents the first large-scale study on the chemical space of inhibitors of dipeptidyl peptidase-4 (DPP4, which is a potential therapeutic protein target for the treatment of diabetes mellitus. Herein, a large set of 2,937 compounds evaluated for their ability to inhibit DPP4 was compiled from the literature. Molecular descriptors were generated from the geometrically optimized low-energy conformers of these compounds at the semiempirical AM1 level. The origins of DPP4 inhibitory activity were elucidated from computed molecular descriptors that accounted for the unique physicochemical properties inherently present in the active and inactive sets of compounds as defined by their respective half maximal inhibitory concentration values of less than 1 µM and greater than 10 µM, respectively. Decision tree analysis revealed the importance of molecular weight, total energy of a molecule, topological polar surface area, lowest unoccupied molecular orbital, and number of hydrogen-bond donors, which correspond to molecular size, energy, surface polarity, electron acceptors, and hydrogen bond donors, respectively. The prediction model was subjected to rigorous independent testing via three external sets. Scaffold and chemical fragment analysis was also performed on these active and inactive sets of compounds to shed light on the distinguishing features of the functional moieties. Docking of representative active DPP4 inhibitors was also performed to unravel key interacting residues. The results of this study are anticipated to be useful in guiding the rational design

  8. Exploring the chemical space of influenza neuraminidase inhibitors

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    Nuttapat Anuwongcharoen

    2016-04-01

    Full Text Available The fight against the emergence of mutant influenza strains has led to the screening of an increasing number of compounds for inhibitory activity against influenza neuraminidase. This study explores the chemical space of neuraminidase inhibitors (NAIs, which provides an opportunity to obtain further molecular insights regarding the underlying basis of their bioactivity. In particular, a large set of 347 and 175 NAIs against influenza A and B, respectively, was compiled from the literature. Molecular and quantum chemical descriptors were obtained from low-energy conformational structures geometrically optimized at the PM6 level. The bioactivities of NAIs were classified as active or inactive according to their half maximum inhibitory concentration (IC50 value in which IC50 < 1µM and ≥ 10µM were defined as active and inactive compounds, respectively. Interpretable decision rules were derived from a quantitative structure–activity relationship (QSAR model established using a set of substructure descriptors via decision tree analysis. Univariate analysis, feature importance analysis from decision tree modeling and molecular scaffold analysis were performed on both data sets for discriminating important structural features amongst active and inactive NAIs. Good predictive performance was achieved as deduced from accuracy and Matthews correlation coefficient values in excess of 81% and 0.58, respectively, for both influenza A and B NAIs. Furthermore, molecular docking was employed to investigate the binding modes and their moiety preferences of active NAIs against both influenza A and B neuraminidases. Moreover, novel NAIs with robust binding fitness towards influenza A and B neuraminidase were generated via combinatorial library enumeration and their binding fitness was on par or better than FDA-approved drugs. The results from this study are anticipated to be beneficial for guiding the rational drug design of novel NAIs for treating influenza

  9. Exploiting Chemical Libraries, Structure, and Genomics in the Search for Kinase Inhibitors

    NARCIS (Netherlands)

    Gray, Nathanael S.; Wodicka, Lisa; Thunnissen, Andy-Mark W.H.; Norman, Thea C.; Kwon, Soojin; Espinoza, F. Hernan; Morgan, David O.; Barnes, Georjana; LeClerc, Sophie; Meijer, Laurent; Kim, Sung-Hou; Lockhart, David J.; Schultz, Peter G.

    1998-01-01

    Selective protein kinase inhibitors were developed on the basis of the unexpected binding mode of 2,6,9-trisubstituted purines to the adenosine triphosphate-binding site of the human cyclin-dependent kinase 2 (CDK2). By iterating chemical library synthesis and biological screening, potent inhibitors

  10. Moduli destabilization via gravitational collapse

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    Hwang, Dong-il [Sogang Univ., Seoul (Korea, Republic of). Center for Quantum Spacetime; Pedro, Francisco G. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Yeom, Dong-han [Sogang Univ., Seoul (Korea, Republic of). Center for Quantum Spacetime; Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics

    2013-06-15

    We examine the interplay between gravitational collapse and moduli stability in the context of black hole formation. We perform numerical simulations of the collapse using the double null formalism and show that the very dense regions one expects to find in the process of black hole formation are able to destabilize the volume modulus. We establish that the effects of the destabilization will be visible to an observer at infinity, opening up a window to a region in spacetime where standard model's couplings and masses can differ significantly from their background values.

  11. Optimizing Dvl PDZ domain inhibitor by exploring chemical space

    Science.gov (United States)

    Shan, Jufang; Zheng, Jie J.

    2009-01-01

    Because of advances in the high-throughput screening technology, identification of a hit that can bind to a target protein has become a relatively easy task; however, in the process of drug discovery, the following hit-to-lead and lead optimization still remain challenging. In a typical hit-to-lead and lead optimization process, the analogues of the most promising hits are synthesized for the development of structure-activity relationship (SAR) analysis, and in turn, in the effort of optimization of lead compounds, such analysis provides guidance for the further synthesis. The synthesis processes are usually long and labor-intensive. In silico searching has becoming an alternative approach to explore SAR especially with millions of compounds ready to be screened and most of them can be easily obtained. Here, we report our discovery of 15 new Dishevelled PDZ domain inhibitors by using such an approach. In our studies, we first developed a pharmacophore model based on NSC668036, an inhibitor previously identified in our laboratory; based on the model, we then screened the ChemDiv database by using an algorithm that combines similarity search and docking procedures; finally, we selected potent inhibitors based on docking analysis and examined them by using NMR spectroscopy. NMR experiments showed that all the 15 compounds we chose bound to the PDZ domain tighter than NSC668036.

  12. Cholinergic Manipulations Bidirectionally Regulate Object Memory Destabilization

    Science.gov (United States)

    Stiver, Mikaela L.; Jacklin, Derek L.; Mitchnick, Krista A.; Vicic, Nevena; Carlin, Justine; O'Hara, Matthew; Winters, Boyer D.

    2015-01-01

    Consolidated memories can become destabilized and open to modification upon retrieval. Destabilization is most reliably prompted when novel information is present during memory reactivation. We hypothesized that the neurotransmitter acetylcholine (ACh) plays an important role in novelty-induced memory destabilization because of its established…

  13. Performance of water-based foams affected by chemical inhibitors to retard spontaneous combustion of coal

    Institute of Scientific and Technical Information of China (English)

    Chen Peng; Huang Fujun; Fu Yue

    2016-01-01

    The micelle generating process of the sodium dodecyl sulfate (SDS) solution with the addition of chemical inhibitors was elucidated using phase separation model, and the descending order of the capacity for the selected chemical inhibitors to reduce the critical micelle concentrations of the solution are MgCl2, CaCl2, NH4HCO3 and NH4Cl. The data to quantitatively describe the foam decay process, including foaming ratio, foam life and decay behaviors, was obtained by pressure measuring system. The results indicate that chemical inhibitors can improve the solution foamability. The capacity of the inhibitors to enhance the solution foamability is sorted as NH4Cl, NH4HCO3, MgCl2 and CaCl2 which can distinctly improve the foam stability as well. The capacity of the inhibitors to enhance the SDS foam stability can be arranged as MgCl2, NH4Cl, NH4HCO3 and CaCl2. It is observed that the gravity drainage plays a leading role in the increase of proportion of diffusion drainage. The oxidation dynamic parameters of the coal samples trea-ted by inhibition foams were investigated using thermal analysis technique, and their synergistic effects on inhibiting coal oxidation were explored.

  14. Study of Cu-Inhibitor State for Post-Chemical Mechanical Polishing Cleaning

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    Harada, Ken; Ito, Atsushi; Kawase, Yasuhiro; Suzuki, Toshiyuki; Hara, Makoto; Sakae, Rina; Kimura, Chiharu; Aoki, Hidemitsu

    2011-05-01

    In order to reduce corrosion on the Cu surface in post-chemical mechanical polishing (CMP) cleaning, controlling the state of inhibitor layers is indispensable. In this study, to investigate the behavior of inhibitor layers in the cleaning process, Cu-benzotriazole (BTA) layers on CuOX were analyzed by electrochemical measurements and surface analysis. Electrochemical measurements revealed that Cu(I)-BTA can prevent corrosion more efficiently than Cu(II)-BTA, and surface analysis revealed that the Cu(I)-BTA layer is thin, whereas the Cu(II)-BTA layer is bulky. The Cu(I)-BTA layer is effective in preventing corrosion of the Cu surface.

  15. Modifying culture conditions in chemical library screening identifies alternative inhibitors of mycobacteria.

    Science.gov (United States)

    Miller, Christopher H; Nisa, Shahista; Dempsey, Sandi; Jack, Cameron; O'Toole, Ronan

    2009-12-01

    In this study, application of a dual absorbance/fluorescence assay to a chemical library screen identified several previously unknown inhibitors of mycobacteria. In addition, growth conditions had a significant effect on the activity profile of the library. Some inhibitors such as Se-methylselenocysteine were detected only when screening was performed under nutrient-limited culture conditions as opposed to nutrient-rich culture conditions. We propose that multiple culture condition library screening is required for complete inhibitory profiling and for maximal antimycobacterial compound detection.

  16. Discovery of small-molecule interleukin-2 inhibitors from a DNA-encoded chemical library.

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    Leimbacher, Markus; Zhang, Yixin; Mannocci, Luca; Stravs, Michael; Geppert, Tim; Scheuermann, Jörg; Schneider, Gisbert; Neri, Dario

    2012-06-18

    Libraries of chemical compounds individually coupled to encoding DNA tags (DNA-encoded chemical libraries) hold promise to facilitate exceptionally efficient ligand discovery. We constructed a high-quality DNA-encoded chemical library comprising 30,000 drug-like compounds; this was screened in 170 different affinity capture experiments. High-throughput sequencing allowed the evaluation of 120 million DNA codes for a systematic analysis of selection strategies and statistically robust identification of binding molecules. Selections performed against the tumor-associated antigen carbonic anhydrase IX (CA IX) and the pro-inflammatory cytokine interleukin-2 (IL-2) yielded potent inhibitors with exquisite target specificity. The binding mode of the revealed pharmacophore against IL-2 was confirmed by molecular docking. Our findings suggest that DNA-encoded chemical libraries allow the facile identification of drug-like ligands principally to any protein of choice, including molecules capable of disrupting high-affinity protein-protein interactions.

  17. Experimental and Numerical Analysis of An Inhibitor-Containing Slurry for Copper Chemical Mechanical Planarization

    Science.gov (United States)

    Zhuang, Yun; Li, Zhonglin; Shimazu, Yoshitomo; Uotani, Nobuo; Borucki, Leonard; Philipossian, Ara

    2005-01-01

    A slurry containing Benzotriazole (BTA) as the inhibitor was analyzed in terms of its frictional, thermal and kinetic attributes for copper CMP applications. The frictional analysis indicated that ‘boundary lubrication’ was the dominant tribological mechanism. Due to the presence of the inhibitor in the slurry, copper removal rate exhibited a highly non-Prestonian behavior. Based on the measured coefficient of friction (\\mathit{COF}) and pad temperature data, a proven thermal model was used to predict wafer temperature. The Preston Equation was used to describe the polishing rate when p× V was lower than 11,000 Pa\\cdotm/s; while a modified Langmuir-Hinshelwood kinetic model was used to simulate the copper removal when p× V was higher than 11,555 Pa\\cdotm/s. Assuming that the adsorbed inhibitor layer was abraded off instantly from the copper surface when p× V was higher than 11,555 Pa\\cdotm/s, the modified Langmuir--Hinshelwood kinetic model indicated that copper polishing was chemically limited in this polishing region.

  18. Synchronization dynamics of chemically coupled cells with activator–inhibitor pathways

    Energy Technology Data Exchange (ETDEWEB)

    Guemkam Ghomsi, P. [Complex Systems and Theoretical Biology Group, Laboratory of Research on Advanced Materials and Nonlinear Science (LaRAMaNS), Department of Physics, Faculty of Science, University of Buea, P.O. Box 63, Buea (Cameroon); Laboratoire de Mécanique, Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé (Cameroon); Moukam Kakmeni, F.M., E-mail: moukam.kakmeni@ubuea.cm [Complex Systems and Theoretical Biology Group, Laboratory of Research on Advanced Materials and Nonlinear Science (LaRAMaNS), Department of Physics, Faculty of Science, University of Buea, P.O. Box 63, Buea (Cameroon); Kofane, T.C.; Tchawoua, C. [Laboratoire de Mécanique, Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé (Cameroon)

    2014-08-01

    Systems of interacting cells containing an activator–inhibitor pathway, regulating naturally in their inner parts their end-product concentrations through a sequence of biochemical reactions with feedback-loops: an end-product inhibition of the first substrate, and an autocatalytic activation of the end-product through an allosteric enzyme-mediated reaction are investigated. The individual cells are considered to be identical and are described by nonlinear differential equations recently proposed following the concerted transition model. The chemical and electrical coupling types, realized by exchange of metabolites across concentration of the cells are used in order to analyze the onset of phase and complete synchronization in the biochemical system. It is found that depending on the coupling nature and the range of coupling strength, cells enter into different synchronization regimes going from low-quality to high-quality synchronization. The synchronization manifold's stability is analyzed. The results are supported by numerical simulations using indicators such as the conditional Lyapunov exponents and the rate of change of the Lyapunov function. The results indicate that the system cannot completely synchronize under the single action of the chemical coupling. The combined effect of both chemical and electrical couplings is found to be of capital importance in the onset of complete synchronization and high quality synchronization. - Highlights: • We investigate the dynamics and synchronization of cells with activator–inhibitor pathways. • A complete study of fixed points' stability and bifurcations of the system is done. • It is found that chemically coupled cells only display phase synchronization. • Electrical coupling is important for complete synchronization in the coupled cells. • High quality synchronization is observed in the coupled cells.

  19. Prevention of PCDD/F formation by chemical inhibitor injection into the flue gases in the incineration processes

    Energy Technology Data Exchange (ETDEWEB)

    Ruuskanen, J.; Halonen, I.; Ruokojaervi, P.; Tuppurainen, K.; Tarhanen, J. [Kuopio Univ. (Finland). Lab. of Environmental Chemistry

    1997-10-01

    Three series of inhibition tests were performed at the laboratory and the pilot scale plants during the years 1995-1996. In the laboratory tests chemical inhibitors were added to fly ash before the thermal treatment. Inhibitors were not found to have any effects on destruction of PCDD/Fs at the torment temperature of 160 and 300 deg C compared to the situation without inhibitors. The thermal treatment at 300 deg C alone reduced and dechlorinated PCDD/Fs effectively. In the pilot scale tests both gaseous and liquid inhibitors were injected to the flue gases at 700 deg C, and gaseous inhibitors also at 400 deg C. The total PCDD/F reductions were between 0-95 % depending on the inhibitor, injection temperature and the amount of inhibitors. In the gaseous inhibitor tests the PCDD/F reductions especially high in the particle phase, being even 98 % in dimethylamine injection. In the liquid inhibitor tests the PCDD/F reductions were also high in the gas phase being even 96 % in sodium ammonium hydrogen phosphate injection. (orig.)

  20. Characterization of Cellulase Enzyme Inhibitors Formed During the Chemical Pretreatments of Rice Straw

    Science.gov (United States)

    Rajan, Kalavathy

    Production of fuels and chemicals from a renewable and inexpensive resource such as lignocellulosic biomass is a lucrative and sustainable option for the advanced biofuel and bio-based chemical platform. Agricultural residues constitute the bulk of potential feedstock available for cellulosic fuel production. On a global scale, rice straw is the largest source of agricultural residues and is therefore an ideal crop model for biomass deconstruction studies. Lignocellulosic biofuel production involves the processes of biomass conditioning, enzymatic saccharification, microbial fermentation and ethanol distillation, and one of the major factors affecting its techno-economic feasibility is the biomass recalcitrance to enzymatic saccharification. Preconditioning of lignocellulosic biomass, using chemical, physico-chemical, mechanical and biological pretreatments, is often practiced such that biomass becomes available to downstream processing. Pretreatments, such as dilute acid and hot water, are effective means of biomass conversion. However, despite their processing importance, preconditioning biomass also results in the production of carbohydrate and lignin degradation products that are inhibitory to downstream saccharification enzymes. The saccharification enzyme cocktail is made up of endo-cellulase, exo-cellulase and beta-glucosidase enzymes, whose role is to cleave cellulose polymers into glucose monomers. Specifically, endo-cellulase and exo-cellulase enzymes cleave cellulose chains in the middle and at the end, resulting in cellobiose molecules, which are hydrolyzed into glucose by beta-glucosidase. Unfortunately, degradation compounds generated during pretreatment inhibit the saccharification enzyme cocktail. Various research groups have identified specific classes of inhibitors formed during biomass pretreatment and have studied their inhibitory effect on the saccharification cocktail. These various research groups prepared surrogate solutions in an attempt to

  1. Discovery of two new inhibitors of Botrytis cinerea chitin synthase by a chemical library screening.

    Science.gov (United States)

    Magellan, Hervé; Boccara, Martine; Drujon, Thierry; Soulié, Marie-Christine; Guillou, Catherine; Dubois, Joëlle; Becker, Hubert F

    2013-09-01

    Chitin synthases polymerize UDP-GlcNAC to form chitin polymer, a key component of fungal cell wall biosynthesis. Furthermore, chitin synthases are desirable targets for fungicides since chitin is absent in plants and mammals. Two potent Botrytis cinerea chitin synthase inhibitors, 2,3,5-tri-O-benzyl-d-ribose (compound 1) and a 2,5-functionalized imidazole (compound 2) were identified by screening a chemical library. We adapted the wheat germ agglutinin (WGA) test for chitin synthase activity detection to allow miniaturization and robotization of the screen. Both identified compounds inhibited chitin synthases in vitro with IC50 values of 1.8 and 10μM, respectively. Compounds 1 and 2 were evaluated for their antifungal activity and were found to be active against B. cinerea BD90 strain with MIC values of 190 and 100μM, respectively. Finally, we discovered that both compounds confer resistance to plant leaves against the attack of the fungus by reducing the propagation of lesions by 37% and 23%, respectively. Based on the inhibitory properties found in different assays, compounds 1 and 2 can be considered as antifungal hit inhibitors of chitin synthase, allowing further optimization of their pharmacological profile to improve their antifungal properties.

  2. Chemical 'Jekyll and Hyde's: small-molecule inhibitors of developmental signaling pathways.

    Science.gov (United States)

    Sakata, Tomoyo; Chen, James K

    2011-08-01

    Small molecules that perturb developmental signaling pathways can have devastating effects on embryonic patterning, as evidenced by the chemically induced onset of cyclopic lambs and children with severely shortened limbs during the 1950s. Recent studies, however, have revealed critical roles for these pathways in human disorders and diseases, spurring the re-examination of these compounds as new targeted therapies. In this tutorial review, we describe four case studies of teratogenic compounds, including inhibitors of the Hedgehog (Hh), Wnt, and bone morphogenetic protein (BMP) pathways. We discuss how these teratogens were discovered, their mechanisms of action, their utility as molecular probes, and their potential as therapeutic agents. We also consider current challenges in the field and possible directions for future research.

  3. Antibiotics GE23077, novel inhibitors of bacterial RNA polymerase. Part 3: Chemical derivatization.

    Science.gov (United States)

    Mariani, Riccardo; Granata, Giorgio; Maffioli, Sonia I; Serina, Stefania; Brunati, Cristina; Sosio, Margherita; Marazzi, Alessandra; Vannini, Alfredo; Patel, Dinesh; White, Richard; Ciabatti, Romeo

    2005-08-15

    GE23077 is a novel RNA polymerase inhibitor that is isolated from the fermentation broth of an Actinomadura sp. It is a cyclic heptapeptide complex made up of four factors, differing in the structure of acyl group connected to the side chain of an alpha,beta-diaminopropanoic acid moiety and in the configuration of the stereocenter of an alpha-amino-malonic acid residue. Although GE23077 shows strong inhibitory activity on both Rifampicin-sensitive and -resistant polymerases, it exhibits poor antimicrobial activity. The most reasonable explanation for this property has been based on the lack of penetration of the molecule across the bacterial membrane, owing to its strong hydrophilic character. To improve penetration, several parts of the molecule were accordingly modified with the aim of altering the physico-chemical properties of GE23077. The current SAR study has identified moieties important for RNA polymerase activity.

  4. THE EFFECT OF METHANOGENIC INHIBITOR FEED ON PROPIONIC ACID AND LAMB MEAT CHEMICAL QUALITY

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    E. Suryanto

    2012-09-01

    Full Text Available This study aimed to determine the effect of medium chain fatty acids (MCFA on propionic acids and lamb meat chemical quality. The treatment given was R1: feed without medium chain fatty acids (MCFA, while R2 dan R3 were the feed contained 1.0% and 1.5% of MCFA, respectively. The twelve heads of lambs yearling weight of 16-17 kg were used as materials. Biological trial was done for three months and then was slaughtered. Before being slaughtered, the animal was taken rumen fluid to be analyzed for propionic acid. The carcass was sampled to be analyzed for chemical composition, cholesterol and fatty acids content. This study showed that methanogenic inhibitor feed with 1.0-1.5% MCFA could be used as sheep feed, and the results: the propionic acid content in rumen increased 29.59 – 36.11%. The cholesterol content decreased 7.14-10.06%. For the meat fatty acids composition, unsaturated fatty acids increased 9.05 – 17.96%. while saturated fatty acid decreased 6.59 – 11.88%.

  5. PENGARUH MEDIA KULTIVASI Chaetoceros gracilis TERHADAP KANDUNGAN KIMIAWI DAN POTENSI INHIBITOR PROTEASE [Effect of Chaetoceros gracilis Cultivation Media to the Chemical Content and Protease Inhibitor Potential

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    Iriani Setyaningsih*

    2013-12-01

    Full Text Available Microalgae produce secondary metabolites with different characteristics for each genus, species or strain. A single species of microalgae can produce several bioactive compounds, including protease inhibitors which can prevent deterioration of fish. In this study, we observed the growth of Chaetoceros gracilis in the media NPSi and NPSi + NaHCO3 and determined the chemical content and the potency of protease inhibitor from Chaetoceros gracilis in both media. The culture was harvested at 8 and 15 days. Screening of protease inhibitor activity was performed by agar diffusion method. Protease inhibitor activity was tested on three pathogenic protease-producing bacteria, namely Staphylococcus aureus, Bacillus cereus and Escherichia coli. The pathogenic bacteria often contaminate foodstuffs. The results showed that media NPSi and NPSi + NaHCO3 affected protein and lipid content of C. gracilis, but the culture age did not affect them. The protein content of C. gracilis cultivated in NPSi media (34.75 and 32.94% was higher than in NPSi + NaHCO3 media (28.13 and 27.13%, while the lipid content was 16.36 and 18.06, 23.86 and 25.40% respectively. Extracts of C. gracilis grown in NPSi and NPSi+NaHCO3 media had inhibitory activity against the test bacteria. Inhibitory activity against E. coli was greater than S. aureus and B. cereus.

  6. Revisiting the flocculation kinetics of destabilized asphaltenes.

    Science.gov (United States)

    Vilas Bôas Fávero, Cláudio; Maqbool, Tabish; Hoepfner, Michael; Haji-Akbari, Nasim; Fogler, H Scott

    2016-07-07

    A comprehensive review of the recently published work on asphaltene destabilization and flocculation kinetics is presented. Four different experimental techniques were used to study asphaltenes undergoing flocculation process in crude oils and model oils. The asphaltenes were destabilized by different n-alkanes and a geometric population balance with the Smoluchowski collision kernel was used to model the asphaltene aggregation process. Additionally, by postulating a relation between the aggregation collision efficiency and the solubility parameter of asphaltenes and the solution, a unified model of asphaltene aggregation model was developed. When the aggregation model is applied to the experimental data obtained from several different crude oil and model oils, the detection time curves collapsed onto a universal single line, indicating that the model successfully captures the underlying physics of the observed process.

  7. Destabilization of free convection by weak rotation

    CERN Document Server

    Gelfgat, Alexander

    2011-01-01

    This study offers an explanation of a recently observed effect of destabilization of free convective flows by weak rotation. After studying several models where flows are driven by a simultaneous action of convection and rotation, it is concluded that the destabilization is observed in the cases where centrifugal force acts against main convective circulation. At relatively low Prandtl numbers this counter action can split the main vortex into two counter rotating vortices, where the interaction leads to instability. At larger Prandtl numbers, the counter action of the centrifugal force steepens an unstable thermal stratification, which triggers Rayleigh-B\\'enard instability mechanism. Both cases can be enhanced by advection of azimuthal velocity disturbances towards the axis, where they grow and excite perturbations of the radial velocity. The effect was studied considering a combined convective/rotating flow in a cylinder with a rotating lid and a parabolic temperature profile at the sidewall. Next, explana...

  8. Study on the Effects of Corrosion Inhibitor According to the Functional Groups for Cu Chemical Mechanical Polishing in Neutral Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Won; Kim, Jae Jeong [Institute of Chemical Process, Seoul National University, Seoul (Korea, Republic of)

    2015-08-15

    As the aluminum (Al) metallization process was replaced with copper (Cu), the damascene process was introduced, which required the planarization step to eliminate over-deposited Cu with Chemical Mechanical Polishing (CMP) process. In this study, the verification of the corrosion inhibitors, one of the Cu CMP slurry components, was conducted to find out the tendency regarding the carboxyl and amino functional group in neutral environment. Through the results of etch rate, removal rate, and chemical ability of corrosion inhibitors based on 1H-1,2,4-triazole as the base corrosion inhibitor, while the amine functional group presents high Cu etching ability, carboxyl functional group shows lower Cu etching ability than base-corrosion inhibitor which means that it increases passivation effect by making strong passivation layer. It implies that the corrosion inhibitor with amine functional group was proper to apply for 1st Cu CMP slurry owing to the high etch rate and with carboxyl functional group was favorable for the 2nd Cu CMP slurry due to the high Cu removal rate/dissolution rate ratio.

  9. Chemical library screening for WNK signalling inhibitors using fluorescence correlation spectroscopy.

    Science.gov (United States)

    Mori, Takayasu; Kikuchi, Eriko; Watanabe, Yuko; Fujii, Shinya; Ishigami-Yuasa, Mari; Kagechika, Hiroyuki; Sohara, Eisei; Rai, Tatemitsu; Sasaki, Sei; Uchida, Shinichi

    2013-11-01

    WNKs (with-no-lysine kinases) are the causative genes of a hereditary hypertensive disease, PHAII (pseudohypoaldosteronism type II), and form a signal cascade with OSR1 (oxidative stress-responsive 1)/SPAK (STE20/SPS1-related proline/alanine-rich protein kinase) and Slc12a (solute carrier family 12) transporters. We have shown that this signal cascade regulates blood pressure by controlling vascular tone as well as renal NaCl excretion. Therefore agents that inhibit this signal cascade could be a new class of antihypertensive drugs. Since the binding of WNK to OSR1/SPAK kinases was postulated to be important for signal transduction, we sought to discover inhibitors of WNK/SPAK binding by screening chemical compounds that disrupt the binding. For this purpose, we developed a high-throughput screening method using fluorescent correlation spectroscopy. As a result of screening 17000 compounds, we discovered two novel compounds that reproducibly disrupted the binding of WNK to SPAK. Both compounds mediated dose-dependent inhibition of hypotonicity-induced activation of WNK, namely the phosphorylation of SPAK and its downstream transporters NKCC1 (Na/K/Cl cotransporter 1) and NCC (NaCl cotransporter) in cultured cell lines. The two compounds could be the promising seeds of new types of antihypertensive drugs, and the method that we developed could be applied as a general screening method to identify compounds that disrupt the binding of two molecules.

  10. Bromophenacyl bromide, a phospholipase A2 inhibitor attenuates chemically induced gastroduodenal ulcers in rats

    Institute of Scientific and Technical Information of China (English)

    Mohammad Tariq; Ibrahim Elfaki; Haseeb Ahmad Khan; Mohammad Arshaduddin; Samia Sobki; Meshal Al Moutaery

    2006-01-01

    AIM: To study the effect of bromophenacyl bromide (BPB), a phospholipase A2 inhibitor on gastric secretion and to protect chemically induced gastric and duodenal ulcers in rats.METHODS: Acid secretion studies were undertaken in pylorus-ligated rats with BPB treatment (0, 5, 15 and 45 mg/kg). Gastric and duodenal lesions in the rats were induced by ethanol and cysteamine respectively. The levels of gastric wall mucus, nonprotein sulfhydryls (NPSH) and myeloperoxidase (MPO) were also measured in the glandular stomach of rats following ethanol induced gastric lesions.RESULTS: BPB produced a dose-dependent inhibition of gastric acid secretion and acidity in rats. Pretreatment with BPB significantly attenuated the formation of ethanol induced gastric lesion. BPB also protected intestinal mucosa against cysteamine-induced duodenal ulcers.The antiulcer activity of BPB was associated with significant inhibition of ethanol-induced depletion of gastric wall mucus, NP-SH and MPO. These findings pointed towards the mediation of sulfhydryls in BPB induced gastrointestinal cytoprotection.CONCLUSION: BPB possesses significant antiulcer and cytoprotective activity against experimentally induced gastroduodenal lesions.

  11. Chemical Genetics Uncovers Novel Inhibitors of Lignification, Including p-Iodobenzoic Acid Targeting CINNAMATE-4-HYDROXYLASE1[OPEN

    Science.gov (United States)

    Van de Wouwer, Dorien; Decou, Raphaël; Audenaert, Dominique; Nguyen, Long

    2016-01-01

    Plant secondary-thickened cell walls are characterized by the presence of lignin, a recalcitrant and hydrophobic polymer that provides mechanical strength and ensures long-distance water transport. Exactly the recalcitrance and hydrophobicity of lignin put a burden on the industrial processing efficiency of lignocellulosic biomass. Both forward and reverse genetic strategies have been used intensively to unravel the molecular mechanism of lignin deposition. As an alternative strategy, we introduce here a forward chemical genetic approach to find candidate inhibitors of lignification. A high-throughput assay to assess lignification in Arabidopsis (Arabidopsis thaliana) seedlings was developed and used to screen a 10-k library of structurally diverse, synthetic molecules. Of the 73 compounds that reduced lignin deposition, 39 that had a major impact were retained and classified into five clusters based on the shift they induced in the phenolic profile of Arabidopsis seedlings. One representative compound of each cluster was selected for further lignin-specific assays, leading to the identification of an aromatic compound that is processed in the plant into two fragments, both having inhibitory activity against lignification. One fragment, p-iodobenzoic acid, was further characterized as a new inhibitor of CINNAMATE 4-HYDROXYLASE, a key enzyme of the phenylpropanoid pathway synthesizing the building blocks of the lignin polymer. As such, we provide proof of concept of this chemical biology approach to screen for inhibitors of lignification and present a broad array of putative inhibitors of lignin deposition for further characterization. PMID:27485881

  12. [Population pressure: a factor of political destabilization].

    Science.gov (United States)

    Tallon, F

    1993-04-01

    Political stability throughout the world appears to be greater in countries with slowly growing populations than in those with rapid growth. Population is not the only influence on political stability, however. The relationship between political stability and development is strong. The rich countries with the slowest growth are the most stable, while poor developing countries with rapid growth suffer from chronic instability. Demographic pressure and density are not the same thing and must be distinguished. A fragile environment like that of the Sahel will experience demographic pressure despite low density. Japan has a greater population density than Rwanda and little cultivable land, but the population has a high standard of living. demographic pressure is not comparable in Japan and Rwanda because Japan has slow population growth and stable democratic political institutions. The rate of growth seems to be a more important element in destabilization than density. Rapid growth creates enormous political tensions especially when profound ethnic divisions exist, and it complicates problems of government by encouraging rapid urbanization. The unbalanced age structures resulting from rapid growth hinder the satisfaction of employment, educational, and health care needs for the ever-increasing masses of young people. 49% of Rwanda's population is under 15 and 66% is under 25. Rwanda is already densely populated, with around 300 inhabitants/sq km, and its population is projected to double in 20 years. 95% of the population is dependent on agriculture, but by 1988 the average landholding per family was only 1.25 hectares and 58% of families did not grown sufficient food for household needs. Further reduction in the size of holdings or a growing landless population will have multiple consequences. Urban migration will inevitably increase, bringing with it all the problems so evident in other poor countries where the process is more advanced than in Rwanda. Chaotic

  13. Amygdala Dopamine Receptors Are Required for the Destabilization of a Reconsolidating Appetitive Memory(1,2).

    Science.gov (United States)

    Merlo, Emiliano; Ratano, Patrizia; Ilioi, Elena C; Robbins, Miranda A L S; Everitt, Barry J; Milton, Amy L

    2015-01-01

    Disrupting maladaptive memories may provide a novel form of treatment for neuropsychiatric disorders, but little is known about the neurochemical mechanisms underlying the induction of lability, or destabilization, of a retrieved consolidated memory. Destabilization has been theoretically linked to the violation of expectations during memory retrieval, which, in turn, has been suggested to correlate with prediction error (PE). It is well-established that PE correlates with dopaminergic signaling in limbic forebrain structures that are critical for emotional learning. The basolateral amygdala is a key neural substrate for the reconsolidation of pavlovian reward-related memories, but the involvement of dopaminergic mechanisms in inducing lability of amygdala-dependent memories has not been investigated. Therefore, we tested the hypothesis that dopaminergic signaling within the basolateral amygdala is required for the destabilization of appetitive pavlovian memories by investigating the effects dopaminergic and protein synthesis manipulations on appetitive memory reconsolidation in rats. Intra-amygdala administration of either the D1-selective dopamine receptor antagonist SCH23390 or the D2-selective dopamine receptor antagonist raclopride prevented memory destabilization at retrieval, thereby protecting the memory from the effects of an amnestic agent, the protein synthesis inhibitor anisomycin. These data show that dopaminergic transmission within the basolateral amygdala is required for memory labilization during appetitive memory reconsolidation.

  14. Quinoxaline derivatives as corrosion inhibitors for mild steel in hydrochloric acid medium: Electrochemical and quantum chemical studies

    Science.gov (United States)

    Olasunkanmi, Lukman O.; Kabanda, Mwadham M.; Ebenso, Eno E.

    2016-02-01

    The corrosion inhibition potential of four quinoxaline derivatives namely, 1-[3-(4-methylphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Me-4-PQPB), 1-(3-(4-methoxyphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl)butan-1-one (Mt-4-PQPB), 1-[3-(3-methoxyphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Mt-3-PQPB) and 1-[3-(2H-1,3-benzodioxol-5-yl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Oxo-1,3-PQPB) was studied for mild steel corrosion in 1 M HCl solution using electrochemical, spectroscopic techniques and quantum chemical calculations. The results of both potentiodynamic polarization and electrochemical impedance spectroscopic studies revealed that the compounds are mixed-type inhibitors and the order of corrosion inhibition efficiency at 100 ppm is Me-4-PQPB>Mt-3-PQPB>Oxo-1,3-PQPB>Mt-4-PQPB. Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopic analyses confirmed the presence of chemical interactions between the inhibitors and mild steel surface. The adsorption of the inhibitor molecules on mild steel surface was found to be both physisorption and chemisorption but predominantly chemisorption. The experimental data obey Langmuir adsorption isotherm. Scanning electron microscopy studies revealed the formation of protective films of the inhibitors on mild steel surface. Quantum chemical parameters obtained from density functional theory (DFT) calculations support experimental results.

  15. Methods Of Using Chemical Libraries To Search For New Kinase Inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Nathanael S. (Berkeley, CA), Schultz, Peter (Oakland, CA), Wodicka, Lisa (Santa Clara, CA), Meijer, Laurent (Roscoff, FR), Lockhart, David J. (Mountain View, CA)

    2003-06-03

    The generation of selective inhibitors for specific protein kinases would provide new tools for analyzing signal transduction pathways and possibly new therapeutic agents. We have invented an approach to the development of selective protein kinase inhibitors based on the unexpected binding mode of 2,6,9-trisubstituted purines to the ATP binding site of human CDK2. The most potent inhibitor, purvalanol B (IC.sub.50 =6 nM), binds with a 30-fold greater affinity than the known CDK2 inhibitor, flavopiridol. The cellular effects of this class of compounds were examined and compared to those of flavopiridol by monitoring changes in mRNA expression levels for all genes in treated cells of Saccharomyces cerevisiae using high-density oligonucleotide probe arrays.

  16. Thermodynamics of protein destabilization in live cells.

    Science.gov (United States)

    Danielsson, Jens; Mu, Xin; Lang, Lisa; Wang, Huabing; Binolfi, Andres; Theillet, François-Xavier; Bekei, Beata; Logan, Derek T; Selenko, Philipp; Wennerström, Håkan; Oliveberg, Mikael

    2015-10-06

    Although protein folding and stability have been well explored under simplified conditions in vitro, it is yet unclear how these basic self-organization events are modulated by the crowded interior of live cells. To find out, we use here in-cell NMR to follow at atomic resolution the thermal unfolding of a β-barrel protein inside mammalian and bacterial cells. Challenging the view from in vitro crowding effects, we find that the cells destabilize the protein at 37 °C but with a conspicuous twist: While the melting temperature goes down the cold unfolding moves into the physiological regime, coupled to an augmented heat-capacity change. The effect seems induced by transient, sequence-specific, interactions with the cellular components, acting preferentially on the unfolded ensemble. This points to a model where the in vivo influence on protein behavior is case specific, determined by the individual protein's interplay with the functionally optimized "interaction landscape" of the cellular interior.

  17. Quantum Chemical-Based Protocol for the Rational Design of Covalent Inhibitors.

    Science.gov (United States)

    Schirmeister, Tanja; Kesselring, Jochen; Jung, Sascha; Schneider, Thomas H; Weickert, Anastasia; Becker, Johannes; Lee, Wook; Bamberger, Denise; Wich, Peter R; Distler, Ute; Tenzer, Stefan; Johé, Patrick; Hellmich, Ute A; Engels, Bernd

    2016-07-13

    We propose a structure-based protocol for the development of customized covalent inhibitors. Starting from a known inhibitor, in the first and second steps appropriate substituents of the warhead are selected on the basis of quantum mechanical (QM) computations and hybrid approaches combining QM with molecular mechanics (QM/MM). In the third step the recognition unit is optimized using docking approaches for the noncovalent complex. These predictions are finally verified by QM/MM or molecular dynamic simulations. The applicability of our approach is successfully demonstrated by the design of reversible covalent vinylsulfone-based inhibitors for rhodesain. The examples show that our approach is sufficiently accurate to identify compounds with the desired properties but also to exclude nonpromising ones.

  18. Steroidal inhibitors as chemical probes of the active site of aromatase.

    Science.gov (United States)

    Brueggemeir, R W; Moh, P P; Ebrahimian, S; Darby, M V

    1993-03-01

    Androstenedione analogs containing 7 alpha-substituents have proven to be potent inhibitors of aromatase in human placental microsomes, in MCF-7 mammary cell cultures, and in JAr choriocarcinoma cells. Recent investigations have focused on the use of mechanism-based inhibitors, such as 7 alpha-substituted 1,4-androstadienediones, to biochemically probe the active site of aromatase. Inhibition kinetics were determined under initial velocity conditions using purified human placental cytochrome P450arom protein in a reconstituted system. Derivatives of 1,4-androstadiene-3,17-dione and 1,4,6-androstatriene-3,17-dione exhibited high affinity in the purified enzyme system. 7 alpha-(4'-Amino)phenylthio-1,4-androstadiene-3,17-dione, abbreviated 7 alpha-APTADD, demonstrated rapid time-dependent, first-order inactivation of reconstituted aromatase activity only in the presence of NADPH. The apparent Kinact for 7 alpha-APTADD is 11.8 nM, the first-order rate of inactivation is 2.72 x 10(-3) sec-1, and the half-time of inactivation at infinite inhibitor concentration is 4.25 min. The values for the rate constant and half-time of inactivation are similar to those observed in the placental microsomal assay system. Further studies were performed with radioiodinated 7 alpha-(4'-iodo)phenylthio-1,4-androstadienedione, 7 alpha-IPTADD, and the reconstituted aromatase system. Incubations with [125I] 7 alpha-IPTADD were followed by protein precipitation, solvent extraction, and column chromatography. Analysis of the isolated cytochrome P450arom by gel electrophoresis and autoradiography demonstrated the presence of only one radioactive band, which corresponded to the protein staining band for cytochrome P450arom. HPLC radiochromatographic analysis of the isolated cytochrome P450aroM confirmed the presence of only one radioactive peak coeluting with the u.v. peak for cytochrome P450arom. Peptide mapping analysis by reverse-phase HPLC of digested inhibitor-cytochrome P450arom complex

  19. Combined Rational Design and a High Throughput Screening Platform for Identifying Chemical Inhibitors of a Ras-activating Enzyme*

    Science.gov (United States)

    Evelyn, Chris R.; Biesiada, Jacek; Duan, Xin; Tang, Hong; Shang, Xun; Papoian, Ruben; Seibel, William L.; Nelson, Sandra; Meller, Jaroslaw; Zheng, Yi

    2015-01-01

    The Ras family small GTPases regulate multiple cellular processes, including cell growth, survival, movement, and gene expression, and are intimately involved in cancer pathogenesis. Activation of these small GTPases is catalyzed by a special class of enzymes, termed guanine nucleotide exchange factors (GEFs). Herein, we developed a small molecule screening platform for identifying lead hits targeting a Ras GEF enzyme, SOS1. We employed an ensemble structure-based virtual screening approach in combination with a multiple tier high throughput experimental screen utilizing two complementary fluorescent guanine nucleotide exchange assays to identify small molecule inhibitors of GEF catalytic activity toward Ras. From a library of 350,000 compounds, we selected a set of 418 candidate compounds predicted to disrupt the GEF-Ras interaction, of which dual wavelength GDP dissociation and GTP-loading experimental screening identified two chemically distinct small molecule inhibitors. Subsequent biochemical validations indicate that they are capable of dose-dependently inhibiting GEF catalytic activity, binding to SOS1 with micromolar affinity, and disrupting GEF-Ras interaction. Mutagenesis studies in conjunction with structure-activity relationship studies mapped both compounds to different sites in the catalytic pocket, and both inhibited Ras signaling in cells. The unique screening platform established here for targeting Ras GEF enzymes could be broadly useful for identifying lead inhibitors for a variety of small GTPase-activating GEF reactions. PMID:25825487

  20. Electrochemical and quantum chemical studies of some indole derivatives as corrosion inhibitors for C38 steel in molar hydrochloric acid

    Energy Technology Data Exchange (ETDEWEB)

    Lebrini, M. [Laboratoire Materiaux et Molecules en Milieu Amazonien, CNRS 8172-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana (France); Robert, F. [Laboratoire Materiaux et Molecules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana (France); Vezin, H. [Laboratoire de Chimie Organique et Macromoleculaire, UMR-CNRS 8009, USTL BatC4 F-59655 Villeneuve d' Ascq Cedex (France); Roos, C., E-mail: christophe.roos@guyane.univ-ag.f [Laboratoire Materiaux et Molecules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana (France)

    2010-10-15

    A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 {sup o}C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The {Delta}G{sub ads}{sup o} values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).

  1. IN SILICO SCREENING OF CHEMICAL COMPOUNDS FROM SWEET FLAG (ARACUS CALAMUS L AS α-GLUCOSIDASE INHIBITOR

    Directory of Open Access Journals (Sweden)

    Dewi Yuliana

    2013-03-01

    Full Text Available Research have been conducted screening in silico chemical compound inhibitor α-glucosidase from plants dringo (Acorus calamus L based on the binding site (binding site are owned by some of the compounds obtained respectively from the inhibition of enzyme / receptor (docking using the program Argus Lab. Model of the enzyme α-glucosidase was obtained through the protein data bank with the code 1lwj in the donwload NCBI website. Models of chemical compounds contained in dringo (A. Calamus L obtained through the site Take out "jamu" Knapsack and made in the formula structures of 2D and 3D using the program ACD / Chemsketch. Docking results showed activity in the compound 1-ethenyl-1-methyl-2,4-at (prop-1-en-2-yl Cyclohexane with free energy - 8.04385 kcal / mol, and the compound Isocaespitol with a free energy - 8.28388 kcal / mol.

  2. Chemical Inhibitors of Non-Homologous End Joining Increase Targeted Construct Integration in Cryptococcus neoformans.

    Science.gov (United States)

    Arras, Samantha D M; Fraser, James A

    2016-01-01

    The development of a biolistic transformation protocol for Cryptococcus neoformans over 25 years ago ushered in a new era of molecular characterization of virulence in this previously intractable fungal pathogen. However, due to the low rate of homologous recombination in this species, the process of creating targeted gene deletions using biolistic transformation remains inefficient. To overcome the corresponding difficulty achieving molecular genetic modifications, members of the Cryptococcus community have investigated the use of specific genetic backgrounds or construct design strategies aimed at reducing ectopic construct integration via non-homologous end joining (NHEJ). One such approach involves deletion of components of the NHEJ-associated Ku heterodimer. While this strategy increases homologous recombination to nearly 100%, it also restricts strain generation to a ku80Δ genetic background and requires subsequent complex mating procedures to reestablish wild-type DNA repair. In this study, we have investigated the ability of known inhibitors of mammalian NHEJ to transiently phenocopy the C. neoformans Ku deletion strains. Testing of eight candidate inhibitors revealed a range of efficacies in C. neoformans, with the most promising compound (W7) routinely increasing the rate of gene deletion to over 50%. We have successfully employed multiple inhibitors to reproducibly enhance the deletion rate at multiple loci, demonstrating a new, easily applied methodology to expedite acquisition of precise genetic alterations in C. neoformans. Based on this success, we anticipate that the use of these inhibitors will not only become widespread in the Cryptococcus community, but may also find use in other fungal species as well.

  3. MIXTURES OF THYROID DISRUPTING CHEMICALS: TESTING ADDITIVITY OF HEPATIC INDUCERS AND THYROID PEROXIDASE INHIBITORS.

    Science.gov (United States)

    Humans are exposed to chemical mixtures via diet, occupation, and the environment. Previous data demonstrated that low doses of polycyclic halogenated aromatic hydrocarbons (PHAHs) acting through similar mechanisms result in an additive reduction of thyroxine (T4). If xenobioti...

  4. Can Small Chemical Modifications of Natural Pan-inhibitors Modulate the Biological Selectivity? The Case of Curcumin Prenylated Derivatives Acting as HDAC or mPGES-1 Inhibitors.

    Science.gov (United States)

    Iranshahi, Mehrdad; Chini, Maria Giovanna; Masullo, Milena; Sahebkar, Amirhossein; Javidnia, Azita; Chitsazian Yazdi, Mahsa; Pergola, Carlo; Koeberle, Andreas; Werz, Oliver; Pizza, Cosimo; Terracciano, Stefania; Piacente, Sonia; Bifulco, Giuseppe

    2015-12-24

    Curcumin, or diferuloylmethane, a polyphenolic molecule isolated from the rhizome of Curcuma longa, is reported to modulate multiple molecular targets involved in cancer and inflammatory processes. On the basis of its pan-inhibitory characteristics, here we show that simple chemical modifications of the curcumin scaffold can regulate its biological selectivity. In particular, the curcumin scaffold was modified with three types of substituents at positions C-1, C-8, and/or C-8' [C5 (isopentenyl, 5-8), C10 (geranyl, 9-12), and C15 (farnesyl, 13, 14)] in order to make these molecules more selective than the parent compound toward two specific targets: histone deacetylase (HDAC) and microsomal prostaglandin E2 synthase-1 (mPGES-1). From combined in silico and in vitro analyses, three selective inhibitors by proper substitution at position 8 were revealed. Compound 13 has improved HDAC inhibitory activity and selectivity with respect to the parent compound, while 5 and 9 block the mPGES-1 enzyme. We hypothesize about the covalent interaction of curcumin, 5, and 9 with the mPGES-1 binding site.

  5. Identification of Chemical Inhibitors of β-Catenin-Driven Liver Tumorigenesis in Zebrafish.

    Directory of Open Access Journals (Sweden)

    Kimberley J Evason

    2015-07-01

    Full Text Available Hepatocellular carcinoma (HCC is one of the most lethal human cancers. The search for targeted treatments has been hampered by the lack of relevant animal models for the genetically diverse subsets of HCC, including the 20-40% of HCCs that are defined by activating mutations in the gene encoding β-catenin. To address this chemotherapeutic challenge, we created and characterized transgenic zebrafish expressing hepatocyte-specific activated β-catenin. By 2 months post fertilization (mpf, 33% of transgenic zebrafish developed HCC in their livers, and 78% and 80% of transgenic zebrafish showed HCC at 6 and 12 mpf, respectively. As expected for a malignant process, transgenic zebrafish showed significantly decreased mean adult survival compared to non-transgenic control siblings. Using this novel transgenic model, we screened for druggable pathways that mediate β-catenin-induced liver growth and identified two c-Jun N-terminal kinase (JNK inhibitors and two antidepressants (one tricyclic antidepressant, amitriptyline, and one selective serotonin reuptake inhibitor that suppressed this phenotype. We further found that activated β-catenin was associated with JNK pathway hyperactivation in zebrafish and in human HCC. In zebrafish larvae, JNK inhibition decreased liver size specifically in the presence of activated β-catenin. The β-catenin-specific growth-inhibitory effect of targeting JNK was conserved in human liver cancer cells. Our other class of hits, antidepressants, has been used in patient treatment for decades, raising the exciting possibility that these drugs could potentially be repurposed for cancer treatment. In support of this proposal, we found that amitriptyline decreased tumor burden in a mouse HCC model. Our studies implicate JNK inhibitors and antidepressants as potential therapeutics for β-catenin-induced liver tumors.

  6. Accelerated generation of human induced pluripotent stem cells with retroviral transduction and chemical inhibitors under physiological hypoxia

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hidenori [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan); Hashimoto, Yoshiya [Department of Biomaterials, Osaka Dental University, 8-1, Hanazonocho, Kuzuha, Hirakatashi, Osaka 573-1121 (Japan); Nakada, Akira; Shigeno, Keiji [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan); Nakamura, Tatsuo, E-mail: nakamura@frontier.kyoto-u.ac.jp [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Very rapid generation of human iPS cells under optimized conditions. Black-Right-Pointing-Pointer Five chemical inhibitors under hypoxia boosted reprogramming. Black-Right-Pointing-Pointer We performed genome-wide DNA methylation analysis. -- Abstract: Induced pluripotent stem (iPS) cells are generated from somatic cells by the forced expression of a defined set of pluripotency-associated transcription factors. Human iPS cells can be propagated indefinitely, while maintaining the capacity to differentiate into all cell types in the body except for extra-embryonic tissues. This technology not only represents a new way to use individual-specific stem cells for regenerative medicine but also constitutes a novel method to obtain large amounts of disease-specific cells for biomedical research. Despite their great potential, the long reprogramming process (up to 1 month) remains one of the most significant challenges facing standard virus-mediated methodology. In this study, we report the accelerated generation of human iPS cells from adipose-derived stem (ADS) cells, using a new combination of chemical inhibitors under a setting of physiological hypoxia in conjunction with retroviral transduction of Oct4, Sox2, Klf4, and L-Myc. Under optimized conditions, we observed human embryonic stem (ES)-like cells as early as 6 days after the initial retroviral transduction. This was followed by the emergence of fully reprogrammed cells bearing Tra-1-81-positive and DsRed transgene-silencing properties on day 10. The resulting cell lines resembled human ES cells in many respects including proliferation rate, morphology, pluripotency-associated markers, global gene expression patterns, genome-wide DNA methylation states, and the ability to differentiate into all three of the germ layers, both in vitro and in vivo. Our method, when combined with chemical inhibitors under conditions of physiological hypoxia, offers a powerful tool for rapidly

  7. Gallic acid as a corrosion inhibitor of carbon steel in chemical decontamination formulation

    Energy Technology Data Exchange (ETDEWEB)

    Keny, S.J.; Kumbhar, A.G. [Reactor Water Chemistry Section, Water and Steam Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 (India); Thinaharan, C. [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai 400 085 (India); Venkateswaran, G. [Reactor Water Chemistry Section, Water and Steam Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 (India)], E-mail: gvenk@magnum.barc.ernet.in

    2008-02-15

    Gallic acid (GA) was found to provide corrosion inhibition to carbon steel (CS) at 4.25 mM concentration. Inherent stability to radiation degradation as compared to other reductant and coupled with its anionic nature with respect to removal using ion exchange column makes it suitable for using as both reductant as well as corrosion inhibitor in dilute decontamination formulations operating in the regenerative mode. A formulation containing CA (1.4 mM), EDTA/NTA (1.4 mM), AA (1.0-2.0 mM) and GA (4.25 mM) was found to be more efficient in dissolving hematite and providing 31% corrosion inhibition (passivation) to the CS.

  8. Organic compounds as corrosion inhibitors for mild steel in acidic media: correlation between inhibition efficiency and chemical structure

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Elizandra C.S.; Chrisman, Erika C.A.N. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Escola de Quimica

    2009-12-19

    The use of inhibitors for mild steels corrosion control which are in contact with aggressive environment is an accepted practice in acid treatment of oil-wells. Organic compounds have been studied to evaluate their corrosion inhibition potential. Film-forming corrosion inhibitors, commonly used to protect oil-field equipment, can be absorbed on the steel surface to give structurally ordered layers. Therefore, the electrons should act as an important role for this adsorption. Studies reveal that organic compounds show significant inhibition efficiency. For this purpose, their molecules should contain N, O and S heteroatoms in various functional groups, long hydrocarbon linear or branched radical and anion and cation active components. However, most of these compounds are not only expensive but also toxic to living beings. According to the 'Green Chemistry' rules, corrosion inhibitors based on organic compounds should be cheap, with low toxicity and have high inhibition efficiency. In this study, the effects of some organic compounds with different groups such as amide, ether, phenyldiamine, anime and aminophenol on the corrosion behavior of mild steel in acidic media have been investigated. The experimental data were obtained by gravimetric measurements. The results show that these compounds reveal a promising corrosion inhibition where phenyldiamine is the most efficient. The effect of molecular structure on the corrosion inhibition efficiency was investigated by semi-empirical quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, and LUMO-HOMO energy gap orbital density were calculated. The relations between the inhibition efficiency and some quantum parameters are discussed and correlations are proposed. The highest values for the HOMO densities were found in the vicinity nitrogen atom, indicating that it is the most probable adsorption center

  9. Chemical-biological characterization of a cruzain inhibitor reveals a second target and a mammalian off-target.

    Science.gov (United States)

    Choy, Jonathan W; Bryant, Clifford; Calvet, Claudia M; Doyle, Patricia S; Gunatilleke, Shamila S; Leung, Siegfried S F; Ang, Kenny K H; Chen, Steven; Gut, Jiri; Oses-Prieto, Juan A; Johnston, Jonathan B; Arkin, Michelle R; Burlingame, Alma L; Taunton, Jack; Jacobson, Matthew P; McKerrow, James M; Podust, Larissa M; Renslo, Adam R

    2013-01-01

    Inhibition of the Trypanosoma cruzi cysteine protease cruzain has been proposed as a therapeutic approach for the treatment of Chagas' disease. Among the best-studied cruzain inhibitors to date is the vinylsulfone K777 (1), which has proven effective in animal models of Chagas' disease. Recent structure-activity studies aimed at addressing potential liabilities of 1 have now produced analogues such as N-[(2S)-1-[[(E,3S)-1-(benzenesulfonyl)-5-phenylpent-1-en-3-yl]amino]-3-(4-methylphenyl)-1-oxopropan-2-yl]pyridine-4-carboxamide (4), which is trypanocidal at ten-fold lower concentrations than for 1. We now find that the trypanocidal activity of 4 derives primarily from the inhibition of T. cruzi 14-α-demethylase (TcCYP51), a cytochrome P450 enzyme involved in the biosynthesis of ergosterol in the parasite. Compound 4 also inhibits mammalian CYP isoforms but is trypanocidal at concentrations below those required to significantly inhibit mammalian CYPs in vitro. A chemical-proteomics approach employing an activity-based probe derived from 1 was used to identify mammalian cathepsin B as a potentially important off-target of 1 and 4. Computational docking studies and the evaluation of truncated analogues of 4 reveal structural determinants for TcCYP51 binding, information that will be useful in further optimization of this new class of inhibitors.

  10. Chemical Genetics Identify eIF2α Kinase Heme Regulated Inhibitor as Anti-Cancer Target

    Science.gov (United States)

    Chen, Ting; Ozel, Duygu; Qiao, Yuan; Harbinski, Fred; Chen, Limo; Denoyelle, Séverine; He, Xiaoying; Zvereva, Nela; Supko, Jeffrey G.; Chorev, Michael; Halperin, Jose A.; Aktas, Bertal H.

    2013-01-01

    Translation initiation plays a critical role in cellular homeostasis, proliferation, differentiation and malignant transformation. Consistently, increasing the abundance of the eIF2·GTP·Met-tRNAi translation initiation complex transforms normal cells and contributes to cancer initiation and the severity of some anemia. The chemical modifiers of the eIF2·GTP·Met-tRNAi ternary complex are therefore invaluable tools for studying its role in the pathobiology of human disorders and for determining if this complex can be pharmacologically targeted for therapeutic purposes. Using a cell based assay, we identified N,N’-diarylureas as novel inhibitors of the ternary complex abundance. Direct functional-genetics and biochemical evidence demonstrated that the N,N’-diarylureas activate heme regulated inhibitor kinase, thereby phosphorylate eIF2α and reduce abundance of the ternary complex. Using tumor cell proliferation in vitro and tumor growth in vivo as paradigms, we demonstrate that N,N’-diarylureas are potent and specific tools for studying the role eIF2·GTP·Met-tRNAi ternary complex in the pathobiology of human disorders. PMID:21765405

  11. Discovery of TNF inhibitors from a DNA-encoded chemical library based on diels-alder cycloaddition.

    Science.gov (United States)

    Buller, Fabian; Zhang, Yixin; Scheuermann, Jörg; Schäfer, Juliane; Bühlmann, Peter; Neri, Dario

    2009-10-30

    DNA-encoded chemical libraries are promising tools for the discovery of ligands toward protein targets of pharmaceutical relevance. DNA-encoded small molecules can be enriched in affinity-based selections and their unique DNA "barcode" allows the amplification and identification by high-throughput sequencing. We describe selection experiments using a DNA-encoded 4000-compound library generated by Diels-Alder cycloadditions. High-throughput sequencing enabled the identification and relative quantification of library members before and after selection. Sequence enrichment profiles corresponding to the "bar-coded" library members were validated by affinity measurements of single compounds. We were able to affinity mature trypsin inhibitors and identify a series of albumin binders for the conjugation of pharmaceuticals. Furthermore, we discovered a ligand for the antiapoptotic Bcl-xL protein and a class of tumor necrosis factor (TNF) binders that completely inhibited TNF-mediated killing of L-M fibroblasts in vitro.

  12. Accelerated generation of human induced pluripotent stem cells with retroviral transduction and chemical inhibitors under physiological hypoxia.

    Science.gov (United States)

    Shimada, Hidenori; Hashimoto, Yoshiya; Nakada, Akira; Shigeno, Keiji; Nakamura, Tatsuo

    2012-01-13

    Induced pluripotent stem (iPS) cells are generated from somatic cells by the forced expression of a defined set of pluripotency-associated transcription factors. Human iPS cells can be propagated indefinitely, while maintaining the capacity to differentiate into all cell types in the body except for extra-embryonic tissues. This technology not only represents a new way to use individual-specific stem cells for regenerative medicine but also constitutes a novel method to obtain large amounts of disease-specific cells for biomedical research. Despite their great potential, the long reprogramming process (up to 1month) remains one of the most significant challenges facing standard virus-mediated methodology. In this study, we report the accelerated generation of human iPS cells from adipose-derived stem (ADS) cells, using a new combination of chemical inhibitors under a setting of physiological hypoxia in conjunction with retroviral transduction of Oct4, Sox2, Klf4, and L-Myc. Under optimized conditions, we observed human embryonic stem (ES)-like cells as early as 6 days after the initial retroviral transduction. This was followed by the emergence of fully reprogrammed cells bearing Tra-1-81-positive and DsRed transgene-silencing properties on day 10. The resulting cell lines resembled human ES cells in many respects including proliferation rate, morphology, pluripotency-associated markers, global gene expression patterns, genome-wide DNA methylation states, and the ability to differentiate into all three of the germ layers, both in vitro and in vivo. Our method, when combined with chemical inhibitors under conditions of physiological hypoxia, offers a powerful tool for rapidly generating bona fide human iPS cells and facilitates the application of iPS cell technology to biomedical research.

  13. Temporally remote destabilization of prediction after rare breaches of expectancy.

    Science.gov (United States)

    Kühn, Anne B; Schubotz, Ricarda I

    2012-08-01

    While neural signatures of breaches of expectancy and their immediate effects have been investigated, thus far, temporally more remote effects have been neglected. The present fMRI study explored neural correlates of temporally remote destabilization of prediction following rare breaches of expectancy with a mean delay of 14 s. We hypothesized temporally remote destabilization to be reflected either in an attenuation of areas related to long-term memory or in an increase of lateral fronto-parietal loops related to the encoding of new stimuli. Monitoring a deterministic 24-digit sequence, subjects were asked to indicate occasional sequential omissions by key press. Temporally remote destabilization of prediction was expected to be revealed by contrasting sequential events whose equivalent was omitted in the preceding sequential run n-1 (destabilized events) with sequential events without such history (nondestabilized events). Temporally remote destabilization of prediction was reflected in an attenuation of activity in the dorsal frontomedian cortex (Brodmann Area (BA) 9) bilaterally. Moreover, activation of the left medial BA 9 was enhanced by contrasting nondestabilized events with breaches. The decrease of dorsal frontomedian activation in the case of destabilized events might be interpreted as a top-down modulation on perception causing a less expectation-restricted encoding of the current stimulus and hence enabling the adaptation of expectation and prediction in the long run.

  14. Ground state destabilization by anionic nucleophiles contributes to the activity of phosphoryl transfer enzymes.

    Directory of Open Access Journals (Sweden)

    Logan D Andrews

    2013-07-01

    Full Text Available Enzymes stabilize transition states of reactions while limiting binding to ground states, as is generally required for any catalyst. Alkaline Phosphatase (AP and other nonspecific phosphatases are some of Nature's most impressive catalysts, achieving preferential transition state over ground state stabilization of more than 10²²-fold while utilizing interactions with only the five atoms attached to the transferred phosphorus. We tested a model that AP achieves a portion of this preference by destabilizing ground state binding via charge repulsion between the anionic active site nucleophile, Ser102, and the negatively charged phosphate monoester substrate. Removal of the Ser102 alkoxide by mutation to glycine or alanine increases the observed Pi affinity by orders of magnitude at pH 8.0. To allow precise and quantitative comparisons, the ionic form of bound P(i was determined from pH dependencies of the binding of Pi and tungstate, a P(i analog lacking titratable protons over the pH range of 5-11, and from the ³¹P chemical shift of bound P(i. The results show that the Pi trianion binds with an exceptionally strong femtomolar affinity in the absence of Ser102, show that its binding is destabilized by ≥10⁸-fold by the Ser102 alkoxide, and provide direct evidence for ground state destabilization. Comparisons of X-ray crystal structures of AP with and without Ser102 reveal the same active site and P(i binding geometry upon removal of Ser102, suggesting that the destabilization does not result from a major structural rearrangement upon mutation of Ser102. Analogous Pi binding measurements with a protein tyrosine phosphatase suggest the generality of this ground state destabilization mechanism. Our results have uncovered an important contribution of anionic nucleophiles to phosphoryl transfer catalysis via ground state electrostatic destabilization and an enormous capacity of the AP active site for specific and strong recognition of the

  15. Effect of proton pump inhibitors on the secretion of bicarbonates and pepsinogen induced by chemical stimulation of the gastric mucosa.

    Science.gov (United States)

    Zolotarev, V A; Khropycheva, R P

    2013-02-01

    Proton pump inhibitors were shown to affect the sensitivity of the gastric mucosa to chemical agents. This effect is associated with inhibition of proton back-diffusion and increase in the permeability of the gastric epithelium. We studied the effect of omeprazole on gastric secretion of bicarbonates and pepsinogen induced by irritation of the gastric mucosa in narcotized rats with a hypertonic solution of high acidity (500 mM NaCl, pH 2.0). Irritation of the gastric mucosa increased the basal secretion of bicarbonates and potentiated the secretion of HCO3(-)and pepsinogen induced by electrostimulation of the vagus nerve. Omeprazole stimulated the prostaglandin-induced increase in the basal secretion of HCO3(-)and pepsinogen. By contrast, bicarbonate production in response to vagal stimulation was suppressed in the presence of omeprazole. Our results indicate that proton pump blockade has a modulatory effect on gastric secretion of bicarbonates and pepsinogen induced by chemical stimulation of the gastric mucosa.

  16. Fragment-hopping-based discovery of a novel chemical series of proto-oncogene PIM-1 kinase inhibitors.

    Directory of Open Access Journals (Sweden)

    Gustavo Saluste

    Full Text Available A new chemical series, triazolo[4,5-b]pyridines, has been identified as an inhibitor of PIM-1 by a chemotype hopping strategy based on a chemically feasible fragment database. In this case, structure-based virtual screening and in silico chemogenomics provide added value to the previously reported strategy of prioritizing among proposed novel scaffolds. Pairwise comparison between compound 3, recently discontinued from Phase I clinical trials, and molecule 8, bearing the selected novel scaffold, shows that the primary activities are similar (IC(50 in the 20 to 150 nM range. At the same time, some ADME properties (for example, an increase of more than 45% in metabolic stability in human liver microsomes and the off-target selectivity (for example, an increase of more than 2 log units in IC(50vs. FLT3 are improved, and the intellectual property (IP position is enhanced. The discovery of a reliable starting point that fulfills critical criteria for a plausible medicinal chemistry project is demonstrated in this prospective study.

  17. Quantum chemical studies of some rhodanine azosulpha drugs as corrosion inhibitors for mild steel in acidic medium

    Science.gov (United States)

    Ebenso, Eno E.; Arslan, Taner; Kandemirli, Fatma; Caner, Necmettin; Love, Ian

    The density functional theory (DFT) at the B3LYP/6-31G (d,p) and B3LYP/6-311G(d,p) basis set levels and ab initio calculations using the HF/6-31G (d,p) and HF/6-311G(d,p) methods were performed on four rhodanine azosulpha drugs (namely 5-sulfadiazineazo-3-phenyl-2-thioxo-4-thiazolidinone, 5- sulfamethazineazo-3-phenyl-2-thioxo-4-thiazolidinone, 5-sulfadimethoxineazo-3-phenyl-2-thioxo- 4-thiazolidinone, and 5-sulfamethoxazoleazo-3-phenyl-2-thioxo-4-thiazolidinone) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between the molecular structure of the rhodanine azosulpha drugs and inhibition efficiency(%IE). The quantum chemical parameters/descriptors, namely, EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy difference (ΔE) between EHOMO and ELUMO, dipole moment (μ), electron affinity (A), ionization potential (I), the absolute electronegativity (X), absolute hardness (η), softness (σ), polarizability (α), the Mulliken charges, and the fraction of electrons (ΔN) transfer from inhibitors to iron, were calculated and correlated with the experimental %IE. Quantitative structure activity relationship (QSAR) approach has been used, and a composite index of some quantum chemical parameters/descriptors was performed to characterize the inhibition performance of the studied molecules. The results showed that the inhibition efficiency (%IE) of the rhodanine azo sulfa drugs studied was closely related to some of the quantum chemical parameters/descriptors but with varying degrees of correlation coefficient (R2). The %IE also increased with the increase in EHOMO and decrease in EHOMO-ELUMO; and the areas containing N atoms are the most possible sites for bonding to the metal iron surface by donating electrons to the metal. The HOMO orbitals consist of 61.73-63.04% double bonded S atom (7(S)), and most of the rest are concentrated on the rhodanine group; so, the

  18. Genomic mechanisms of stress tolerance for the industrial yeast Saccharomyces cerevisiae against the major chemical classes of inhibitors derived from lignocellulosic biomass conversion

    Science.gov (United States)

    Scientists at ARS developed tolerant industrial yeast that is able to reduce major chemical classes of inhibitors into less toxic or none toxic compounds while producing ethanol. Using genomic studies, we defined mechanisms of in situ detoxification involved in novel gene functions, vital cofactor r...

  19. High-Throughput Chemical Screens Identify Disulfiram as an Inhibitor of Human Glioblastoma Stem Cells

    Science.gov (United States)

    Hothi, Parvinder; Martins, Timothy J.; Chen, LiPing; Deleyrolle, Loic; Yoon, Jae-Geun; Reynolds, Brent; Foltz, Greg

    2012-01-01

    Glioblastoma Multiforme (GBM) continues to have a poor patient prognosis despite optimal standard of care. Glioma stem cells (GSCs) have been implicated as the presumed cause of tumor recurrence and resistance to therapy. With this in mind, we screened a diverse chemical library of 2,000 compounds to identify therapeutic agents that inhibit GSC proliferation and therefore have the potential to extend patient survival. High-throughput screens (HTS) identified 78 compounds that repeatedly inhibited cellular proliferation, of which 47 are clinically approved for other indications and 31 are experimental drugs. Several compounds (such as digitoxin, deguelin, patulin and phenethyl caffeate) exhibited high cytotoxicity, with half maximal inhibitory concentrations (IC50) in the low nanomolar range. In particular, the FDA approved drug for the treatment of alcoholism, disulfiram (DSF), was significantly potent across multiple patient samples (IC50 of 31.1 nM). The activity of DSF was potentiated by copper (Cu), which markedly increased GSC death. DSF–Cu inhibited the chymotrypsin-like proteasomal activity in cultured GSCs, consistent with inactivation of the ubiquitin-proteasome pathway and the subsequent induction of tumor cell death. Given that DSF is a relatively non-toxic drug that can penetrate the blood-brain barrier, we suggest that DSF should be tested (as either a monotherapy or as an adjuvant) in pre-clinical models of human GBM. Data also support targeting of the ubiquitin-proteasome pathway as a therapeutic approach in the treatment of GBM. PMID:23165409

  20. Chemical design of a radiolabeled gelatinase inhibitor peptide for the imaging of gelatinase activity in tumors

    Energy Technology Data Exchange (ETDEWEB)

    Hanaoka, Hirofumi [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Kyoto 606-8501 (Japan); Graduate School of Medicine, Gunma University, Maebashi 371-8511 (Japan); Mukai, Takahiro [Graduate School of Medicine, Kyoto University, Kyoto 606-8507 (Japan); Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582 (Japan); Habashita, Sayo [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Kyoto 606-8501 (Japan); Asano, Daigo [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Kyoto 606-8501 (Japan); Ogawa, Kazuma [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Kyoto 606-8501 (Japan); Kuroda, Yoshihiro [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Kyoto 606-8501 (Japan); Akizawa, Hiromichi [Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675 (Japan); Iida, Yasuhiko [Graduate School of Medicine, Gunma University, Maebashi 371-8511 (Japan); Endo, Keigo [Graduate School of Medicine, Gunma University, Maebashi 371-8511 (Japan); Saga, Tsuneo [Graduate School of Medicine, Kyoto University, Kyoto 606-8507 (Japan); Saji, Hideo [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Kyoto 606-8501 (Japan)]. E-mail: hsaji@pharm.kyoto-u.ac.jp

    2007-07-15

    Since elevated levels of gelatinases [matrix metalloproteinase (MMP)-2 and MMP-9] are associated with a poor prognosis in cancer patients, these enzymes are potential targets for tumor imaging. In the present study, a cyclic decapeptide, cCTTHWGFTLC (CTT), was selected as a mother compound because of its selective inhibitory activity toward gelatinases. For imaging gelatinase activity in tumors, we designed a CTT-based radiopharmaceutical taking into consideration that (1) the HWGF motif of the peptide is important for the activity (2) hydrophilic radiolabeled peptides show low-level accumulation in the liver and (3) an increase in the negative charge of radiolabeled peptides is effective in reducing renal accumulation. Thus, a highly hydrophilic and negatively charged radiolabel, indiun-111-diethylenetriaminepentaacetic acid ({sup 111}In-DTPA), was attached to an N-terminal residue distant from the HWGF motif ({sup 111}In-DTPA-CTT). In MMP-2 inhibition assays, In-DTPA-CTT significantly inhibited the proteolytic activity in a concentration-dependent fashion. When injected into normal mice, {sup 111}In-DTPA-CTT showed low levels of radioactivity in the liver and kidney. A comparison of the pharmacokinetic characteristics of {sup 111}In-DTPA-CTT with those of other CTT derivatives having different physicochemical properties revealed that the increase in hydrophilicity and negative charge caused by the conjugation of {sup 111}In-DTPA reduced levels of radioactivity in the liver and kidney. In tumor-bearing mice, a significant correlation was observed between the accumulation in the tumor as well as tumor-to-blood ratio of {sup 111}In-DTPA-CTT and gelatinase activity. These findings support the validity of the chemical design of {sup 111}In-DTPA-CTT for reducing accumulation in nontarget tissues and maintaining the inhibitory activity of the mother compound. Furthermore, {sup 111}In-DTPA-CTT derivatives would be potential radiopharmaceuticals for the imaging of

  1. Destabilization and intracranial fragmentation of a full metal jacket bullet.

    Science.gov (United States)

    Farrugia, A; Raul, J S; Geraut, A; Tortel, M C; Ludes, B

    2009-10-01

    We report a case with an atypical entrance wound as a result of a destabilized full metal jacket bullet penetration. The destabilized bullet by an impact with the dorsal hand experiences a yawing to tumbling motion in flight. The large angle of yaw induces a larger presenting profile upon impact that contributes, associated to a rapid deceleration, to a greater mechanical force on the projectile structure and a fragmentation into core and jacket. Forensic pathologists have to be aware that the metal jacket bullet could tend to break up outside or inside the body particularly after a shooting through a target. This phenomenon induces atypical entrance wounds and atypical X-ray presentation.

  2. Phenotypic chemical screening using a zebrafish neural crest EMT reporter identifies retinoic acid as an inhibitor of epithelial morphogenesis.

    Science.gov (United States)

    Jimenez, Laura; Wang, Jindong; Morrison, Monique A; Whatcott, Clifford; Soh, Katherine K; Warner, Steven; Bearss, David; Jette, Cicely A; Stewart, Rodney A

    2016-04-01

    The epithelial-to-mesenchymal transition (EMT) is a highly conserved morphogenetic program essential for embryogenesis, regeneration and cancer metastasis. In cancer cells, EMT also triggers cellular reprogramming and chemoresistance, which underlie disease relapse and decreased survival. Hence, identifying compounds that block EMT is essential to prevent or eradicate disseminated tumor cells. Here, we establish a whole-animal-based EMT reporter in zebrafish for rapid drug screening, calledTg(snai1b:GFP), which labels epithelial cells undergoing EMT to producesox10-positive neural crest (NC) cells. Time-lapse and lineage analysis ofTg(snai1b:GFP)embryos reveal that cranial NC cells delaminate from two regions: an early population delaminates adjacent to the neural plate, whereas a later population delaminates from within the dorsal neural tube. TreatingTg(snai1b:GFP)embryos with candidate small-molecule EMT-inhibiting compounds identified TP-0903, a multi-kinase inhibitor that blocked cranial NC cell delamination in both the lateral and medial populations. RNA sequencing (RNA-Seq) analysis and chemical rescue experiments show that TP-0903 acts through stimulating retinoic acid (RA) biosynthesis and RA-dependent transcription. These studies identify TP-0903 as a new therapeutic for activating RAin vivoand raise the possibility that RA-dependent inhibition of EMT contributes to its prior success in eliminating disseminated cancer cells.

  3. Phenotypic chemical screening using a zebrafish neural crest EMT reporter identifies retinoic acid as an inhibitor of epithelial morphogenesis

    Directory of Open Access Journals (Sweden)

    Laura Jimenez

    2016-04-01

    Full Text Available The epithelial-to-mesenchymal transition (EMT is a highly conserved morphogenetic program essential for embryogenesis, regeneration and cancer metastasis. In cancer cells, EMT also triggers cellular reprogramming and chemoresistance, which underlie disease relapse and decreased survival. Hence, identifying compounds that block EMT is essential to prevent or eradicate disseminated tumor cells. Here, we establish a whole-animal-based EMT reporter in zebrafish for rapid drug screening, called Tg(snai1b:GFP, which labels epithelial cells undergoing EMT to produce sox10-positive neural crest (NC cells. Time-lapse and lineage analysis of Tg(snai1b:GFP embryos reveal that cranial NC cells delaminate from two regions: an early population delaminates adjacent to the neural plate, whereas a later population delaminates from within the dorsal neural tube. Treating Tg(snai1b:GFP embryos with candidate small-molecule EMT-inhibiting compounds identified TP-0903, a multi-kinase inhibitor that blocked cranial NC cell delamination in both the lateral and medial populations. RNA sequencing (RNA-Seq analysis and chemical rescue experiments show that TP-0903 acts through stimulating retinoic acid (RA biosynthesis and RA-dependent transcription. These studies identify TP-0903 as a new therapeutic for activating RA in vivo and raise the possibility that RA-dependent inhibition of EMT contributes to its prior success in eliminating disseminated cancer cells.

  4. Corrosion inhibitor mechanisms on reinforcing steel in Portland cement pastes

    Science.gov (United States)

    Martin, Farrel James

    2001-07-01

    The mechanisms of corrosion inhibitor interaction with reinforcing steel are investigated in the present work, with particular emphasis on effects associated with corrosion inhibitors admixed into Portland cement paste. The principal objective in reinforcing steel corrosion inhibition for Portland cement concrete is observed to be preservation of the naturally passive steel surface condition established by the alkaline environment. Introduction of chloride ions to the steel surface accelerates damage to the passive film. Excessive damage to the passive film leads to loss of passivity and a destabilization of conditions that facilitate repair of the passive film. Passive film preservation in presence of chloride ions is achieved either through stabilization of the passive film or by modification of the chemical environment near the steel surface. Availability of inhibitors to the steel surface and their tendency to stabilize passive film defects are observed to be of critical importance. Availability of admixed corrosion inhibitors to the passive film is affected by binding of inhibitors during cement paste hydration. It is determined that pore solution concentrations of inorganic admixed inhibitors tend to be lower than the admixed concentration, while pore solution concentrations of organic admixed inhibitors tend to be higher than the admixed concentration. A fundamental difference of inhibitor function is observed between film-forming and defect stabilizing corrosion inhibitors. Experiments are conducted using coupons of reinforcing steel that are exposed to environments simulating chloride-contaminated Portland cement concrete. A study of the steel/cement paste interface is also performed, and compounds forming at this interface are identified using X-Ray diffraction.

  5. Stabilizing versus destabilizing the microtubules: a double-edge sword for an effective cancer treatment option?

    Science.gov (United States)

    Fanale, Daniele; Bronte, Giuseppe; Passiglia, Francesco; Calò, Valentina; Castiglia, Marta; Di Piazza, Florinda; Barraco, Nadia; Cangemi, Antonina; Catarella, Maria Teresa; Insalaco, Lavinia; Listì, Angela; Maragliano, Rossella; Massihnia, Daniela; Perez, Alessandro; Toia, Francesca; Cicero, Giuseppe; Bazan, Viviana

    2015-01-01

    Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy.

  6. Stabilizing versus Destabilizing the Microtubules: A Double-Edge Sword for an Effective Cancer Treatment Option?

    Science.gov (United States)

    Fanale, Daniele; Bronte, Giuseppe; Passiglia, Francesco; Calò, Valentina; Castiglia, Marta; Di Piazza, Florinda; Barraco, Nadia; Cangemi, Antonina; Catarella, Maria Teresa; Insalaco, Lavinia; Listì, Angela; Maragliano, Rossella; Massihnia, Daniela; Perez, Alessandro; Toia, Francesca; Cicero, Giuseppe; Bazan, Viviana

    2015-01-01

    Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy. PMID:26484003

  7. State-dependent effect of dopamine D₁/D₅ receptors inactivation on memory destabilization and reconsolidation.

    Science.gov (United States)

    Rossato, Janine I; Köhler, Cristiano A; Radiske, Andressa; Lima, Ramón H; Bevilaqua, Lia R M; Cammarota, Martín

    2015-05-15

    Object recognition memories (ORM) can incorporate new information upon reactivation. This update initially involves destabilization of the original memory, which is followed by restabilization of the upgraded engram through a reconsolidation process that requires gene expression and protein synthesis in the hippocampus. We found that when given in dorsal CA1 either immediately after training or 15 min before ORM reactivation in the presence of a novel object, the dopamine D1/D5 receptor antagonist SCH23390 did not affect ORM consolidation, expression or retention but impeded the amnesia caused by the post-retrieval administration of the mRNA synthesis inhibitor α-amanitin or the protein synthesis blocker anisomycin. This anti-amnesic effect was not observed when SCH23390 was given immediately after training and again 15 min before memory reactivation. Our results demonstrate that hippocampal D1/D5 receptors are not needed for formation, retrieval or post-retrieval restabilization of the ORM trace but are essential for its destabilization when reactivation occurs together with the incorporation of new information into the original memory. Importantly, they also suggest that reenactment of the animal's post-learning neurochemical milieu at the moment of memory reactivation can be a boundary condition for reconsolidation.

  8. Stabilizing versus Destabilizing the Microtubules: A Double-Edge Sword for an Effective Cancer Treatment Option?

    Directory of Open Access Journals (Sweden)

    Daniele Fanale

    2015-01-01

    Full Text Available Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy.

  9. How Do Amateur Soccer Referees Destabilize a Match?

    Science.gov (United States)

    Fruchart, Eric; Carton, Annie

    2012-01-01

    The refereeing system in amateur football is not without weakness. Some referees could be deliberately led to destabilize a match in order to demonstrate their skills in regulating a situation of potential conflict. This has posed an ethical problem to soccer institutions. Our study proposes to focus on this phenomenon by questioning seventy four…

  10. Destabilizing DNA during Rejoining Enhances Fidelity of Repair.

    Directory of Open Access Journals (Sweden)

    Richard Robinson

    2015-08-01

    Full Text Available A new study shows that during repair of DNA, the effect of a single-strand annealing protein is to destabilize DNA duplex formation so that annealing only occurs between perfectly matched strands; the protein then clamps the strands together for repair. Read the Research Article.

  11. Discovery of new acylaminopyridines as GSK-3 inhibitors by a structure guided in-depth exploration of chemical space around a pyrrolopyridinone core.

    Science.gov (United States)

    Sivaprakasam, Prasanna; Han, Xiaojun; Civiello, Rita L; Jacutin-Porte, Swanee; Kish, Kevin; Pokross, Matt; Lewis, Hal A; Ahmed, Nazia; Szapiel, Nicolas; Newitt, John A; Baldwin, Eric T; Xiao, Hong; Krause, Carol M; Park, Hyunsoo; Nophsker, Michelle; Lippy, Jonathan S; Burton, Catherine R; Langley, David R; Macor, John E; Dubowchik, Gene M

    2015-05-01

    Glycogen synthase kinase-3 (GSK-3) has been proposed to play a crucial role in the pathogenesis of many diseases including cancer, stroke, bipolar disorders, diabetes and neurodegenerative diseases. GSK-3 inhibition has been a major area of pharmaceutical interest over the last two decades. A plethora of reports appeared recently on selective inhibitors and their co-crystal structures in GSK-3β. We identified several series of promising new GSK-3β inhibitors from a coherent design around a pyrrolopyridinone core structure. A systematic exploration of the chemical space around the central spacer led to potent single digit and sub-nanomolar GSK-3β inhibitors. When dosed orally in a transgenic mouse model of Alzheimer's disease (AD), an exemplary compound showed significant lowering of Tau phosphorylation at one of the GSK-3 phosphorylating sites, Ser396. X-ray crystallography greatly aided in validating the binding hypotheses.

  12. Inhibition of AmpC beta-lactamase through a destabilizing interaction in the active site

    Energy Technology Data Exchange (ETDEWEB)

    Trehan, I.; Beadle, B.M.; Shoichet, B.K. (NWU)

    2010-03-08

    {beta}-Lactamases hydrolyze {beta}-lactam antibiotics, including penicillins and cephalosporins; these enzymes are the most widespread resistance mechanism to these drugs and pose a growing threat to public health. {beta}-Lactams that contain a bulky 6(7){alpha} substituent, such as imipenem and moxalactam, actually inhibit serine {beta}-lactamases and are widely used for this reason. Although mutant serine {beta}-lactamases have arisen that hydrolyze {beta}-lactamase resistant {beta}-lactams (e.g., ceftazidime) or avoid mechanism-based inhibitors (e.g., clavulanate), mutant serine {beta}-lactamases have not yet arisen in the clinic with imipenemase or moxalactamase activity. Structural and thermodynamic studies suggest that the 6(7){alpha} substituents of these inhibitors form destabilizing contacts within the covalent adduct with the conserved Asn152 in class C {beta}-lactamases (Asn132 in class A {beta}-lactamases). This unfavorable interaction may be crucial to inhibition. To test this destabilization hypothesis, we replaced Asn152 with Ala in the class C {beta}-lactamase AmpC from Escherichia coli and examined the mutant enzyme's thermodynamic stability in complex with imipenem and moxalactam. Consistent with the hypothesis, the Asn152 {yields} Ala substitution relieved 0.44 and 1.10 kcal/mol of strain introduced by imipenem and moxalactam, respectively, relative to the wild-type complexes. However, the kinetic efficiency of AmpC N152A was reduced by 6300-fold relative to that of the wild-type enzyme. To further investigate the inhibitor's interaction with the mutant enzyme, the X-ray crystal structure of moxalactam in complex with N152A was determined to a resolution of 1.83 {angstrom}. Moxalactam in the mutant complex is significantly displaced from its orientation in the wild-type complex; however, moxalactam does not adopt an orientation that would restore competence for hydrolysis. Although Asn152 forces {beta}-lactams with 6(7){alpha

  13. Different pH-sensitivity patterns of 30 sodium channel inhibitors suggest chemically different pools along the access pathway

    Science.gov (United States)

    Lazar, Alexandra; Lenkey, Nora; Pesti, Krisztina; Fodor, Laszlo; Mike, Arpad

    2015-01-01

    The major drug binding site of sodium channels is inaccessible from the extracellular side, drug molecules can only access it either from the membrane phase, or from the intracellular aqueous phase. For this reason, ligand-membrane interactions are as important determinants of inhibitor properties, as ligand-protein interactions. One-way to probe this is to modify the pH of the extracellular fluid, which alters the ratio of charged vs. uncharged forms of some compounds, thereby changing their interaction with the membrane. In this electrophysiology study we used three different pH values: 6.0, 7.3, and 8.6 to test the significance of the protonation-deprotonation equilibrium in drug access and affinity. We investigated drugs of several different indications: carbamazepine, lamotrigine, phenytoin, lidocaine, bupivacaine, mexiletine, flecainide, ranolazine, riluzole, memantine, ritanserin, tolperisone, silperisone, ambroxol, haloperidol, chlorpromazine, clozapine, fluoxetine, sertraline, paroxetine, amitriptyline, imipramine, desipramine, maprotiline, nisoxetine, mianserin, mirtazapine, venlafaxine, nefazodone, and trazodone. We recorded the pH-dependence of potency, reversibility, as well as onset/offset kinetics. As expected, we observed a strong correlation between the acidic dissociation constant (pKa) of drugs and the pH-dependence of their potency. Unexpectedly, however, the pH-dependence of reversibility or kinetics showed diverse patterns, not simple correlation. Our data are best explained by a model where drug molecules can be trapped in at least two chemically different environments: A hydrophilic trap (which may be the aqueous cavity within the inner vestibule), which favors polar and less lipophilic compounds, and a lipophilic trap (which may be the membrane phase itself, and/or lipophilic binding sites on the channel). Rescue from the hydrophilic and lipophilic traps can be promoted by alkalic and acidic extracellular pH, respectively. PMID:26441665

  14. Different pH-sensitivity patterns of 30 sodium channel inhibitors suggest chemically different pools along the access pathway.

    Directory of Open Access Journals (Sweden)

    Alexandra eLazar

    2015-09-01

    Full Text Available The major drug binding site of sodium channels is inaccessible from the extracellular side, drug molecules can only access it either from the membrane phase, or from the intracellular aqueous phase. For this reason, ligand-membrane interactions are as important determinants of inhibitor properties, as ligand-protein interactions. One way to probe this is to modify the pH of the extracellular fluid, which alters the ratio of charged vs. uncharged forms of some compounds, thereby changing their interaction with the membrane. In this electrophysiology study we used three different pH values: 6.0, 7.3 and 8.6 to test the significance of the protonation-deprotonation equilibrium in drug access and affinity. We investigated drugs of several different indications: carbamazepine, lamotrigine, phenytoin, lidocaine, bupivacaine, mexiletine, flecainide, ranolazine, riluzole, memantine, ritanserin, tolperisone, silperisone, ambroxol, haloperidol, chlorpromazine, clozapine, fluoxetine, sertraline, paroxetine, amitriptyline, imipramine, desipramine, maprotiline, nisoxetine, mianserin, mirtazapine, venlafaxine, nefazodone and trazodone. We recorded the pH-dependence of potency, reversibility, as well as onset/offset kinetics. As expected, we observed a strong correlation between the acidic dissociation constant (pKa of drugs and the pH-dependence of their potency. Unexpectedly, however, the pH-dependence of reversibility or kinetics showed diverse patterns, not simple correlation. Our data are best explained by a model where drug molecules can be trapped in at least two chemically different environments: A hydrophilic trap (which may be the aqueous cavity within the inner vestibule, which favors polar and less lipophilic compounds, and a lipophilic trap (which may be the membrane phase itself, and/or lipophilic binding sites on the channel. Rescue from the hydrophilic and lipophilic traps can be promoted by alkalic and acidic extracellular pH, respectively.

  15. A chemically defined culture medium containing Rho kinase inhibitor Y-27632 for the fabrication of stratified squamous epithelial cell grafts

    Energy Technology Data Exchange (ETDEWEB)

    Aslanova, Afag [Department of Surgery, Institute of Gastroenterology, Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Institute of Advanced Biomedical Engineering and Science, Tokyo Women' s Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Takagi, Ryo; Yamato, Masayuki; Okano, Teruo [Institute of Advanced Biomedical Engineering and Science, Tokyo Women' s Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Yamamoto, Masakazu, E-mail: yamamoto.ige@twmu.ac.jp [Department of Surgery, Institute of Gastroenterology, Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan)

    2015-05-01

    With the development of a culture method for stratified squamous epithelial cells, tissue-engineered epithelial cell sheets have been successfully applied as clinical cell grafts. However, the implementation of these cell sheets without the use of any animal-derived materials is highly desirable. In this study, Rho-associated protein kinase inhibitor Y-27632 was used to develop a chemically defined culture medium for the fabrication of stratified epithelial cell grafts consisting of human epidermal and oral keratinocytes, and the proliferation activity, cell morphology, and gene expressions of the keratinocytes were analyzed. The results of a colorimetric assay indicated that Y-27632 significantly promoted the proliferation of the keratinocytes in culture media both with and without fetal bovine serum (FBS), although there were no indications of Y-27632 efficacy on cell morphology and stratification of the keratinocytes in culture medium without any animal-derived materials. The results of quantitative RT-PCR revealed that gene expressions correlated with cell adhesion, cell–cell junction, proliferation markers, and stem/progenitor markers in cultured keratinocytes were not strongly affected by the addition of Y-27632 to the culture medium. Moreover, gene expressions of differentiation markers in stratified keratinocytes cultured in medium without FBS were nearly identical to those of keratinocytes co-cultured with 3T3 feeder cells. Interestingly, the expressions of differentiation markers in cultured stratified keratinocytes were suppressed by FBS, whereas they were reconstructed by either co-culture of a 3T3 feeder layer or addition of Y-27632 into the culture medium containing FBS. These findings indicate that Y-27632 is a useful supplement for the development of a chemically defined culture medium for fabrication of stratified epithelial cell grafts for clinical applications for the purpose of developing the culture medium with a lower risk of pathogen

  16. A sycamore cell wall polysaccharide and a chemically related tomato leaf polysaccharide possess similar proteinase inhibitor-inducing activities.

    Science.gov (United States)

    Ryan, C A; Bishop, P; Pearce, G

    1981-09-01

    A large pectic polysaccharide, called rhamnogalacturonan I, that is solubilized by a fungal endo-alpha-1,4-polygalacturonase from the purified walls of suspension-cultured sycamore cells possesses proteinase inhibitor-inducing activity similar to that of the proteinase inhibitor-inducing factor, a pectic-like oligosaccharide fraction isolated from tomato leaves. This suggests that the proteinase inhibitor-inducing activity resides in particular polysaccharide fragments which can be released when plant cell walls are exposed to appropriate enzyme degradation as a result of either wounding or pest attack.

  17. Modeling chemical interaction profiles: I. Spectral data-activity relationship and structure-activity relationship models for inhibitors and non-inhibitors of cytochrome P450 CYP3A4 and CYP2D6 isozymes.

    Science.gov (United States)

    McPhail, Brooks; Tie, Yunfeng; Hong, Huixiao; Pearce, Bruce A; Schnackenberg, Laura K; Ge, Weigong; Valerio, Luis G; Fuscoe, James C; Tong, Weida; Buzatu, Dan A; Wilkes, Jon G; Fowler, Bruce A; Demchuk, Eugene; Beger, Richard D

    2012-03-15

    An interagency collaboration was established to model chemical interactions that may cause adverse health effects when an exposure to a mixture of chemicals occurs. Many of these chemicals--drugs, pesticides, and environmental pollutants--interact at the level of metabolic biotransformations mediated by cytochrome P450 (CYP) enzymes. In the present work, spectral data-activity relationship (SDAR) and structure-activity relationship (SAR) approaches were used to develop machine-learning classifiers of inhibitors and non-inhibitors of the CYP3A4 and CYP2D6 isozymes. The models were built upon 602 reference pharmaceutical compounds whose interactions have been deduced from clinical data, and 100 additional chemicals that were used to evaluate model performance in an external validation (EV) test. SDAR is an innovative modeling approach that relies on discriminant analysis applied to binned nuclear magnetic resonance (NMR) spectral descriptors. In the present work, both 1D ¹³C and 1D ¹⁵N-NMR spectra were used together in a novel implementation of the SDAR technique. It was found that increasing the binning size of 1D ¹³C-NMR and ¹⁵N-NMR spectra caused an increase in the tenfold cross-validation (CV) performance in terms of both the rate of correct classification and sensitivity. The results of SDAR modeling were verified using SAR. For SAR modeling, a decision forest approach involving from 6 to 17 Mold2 descriptors in a tree was used. Average rates of correct classification of SDAR and SAR models in a hundred CV tests were 60% and 61% for CYP3A4, and 62% and 70% for CYP2D6, respectively. The rates of correct classification of SDAR and SAR models in the EV test were 73% and 86% for CYP3A4, and 76% and 90% for CYP2D6, respectively. Thus, both SDAR and SAR methods demonstrated a comparable performance in modeling a large set of structurally diverse data. Based on unique NMR structural descriptors, the new SDAR modeling method complements the existing SAR

  18. Analysis of specific mRNA destabilization during Dictyostelium development.

    Science.gov (United States)

    Mangiarotti, G; Bulfone, S; Giorda, R; Morandini, P; Ceccarelli, A; Hames, B D

    1989-07-01

    A number of specific mRNAs are destabilized upon disaggregation of developing Dictyostelium discoideum cells. Analysis of a family of cloned genes indicates that only prespore-enriched mRNAs are affected; constitutive mRNAs that are expressed throughout development and mRNAs that accumulate preferentially in prestalk cells are stable under these conditions. The decay of sensitive prespore mRNAs can be halted by allowing the cells to reaggregate, indicating that destabilization occurs by the progressive selection of individual molecules rather than on all members of an mRNA subpopulation at the time of disaggregation. Individual molecules of the sensitive mRNA species remain engaged in protein synthesis in the disaggregated cells until selected. Destabilization of sensitive mRNAs is induced by cell dissociation even in the presence of concentrations of nogalamycin that inhibit RNA synthesis. The reported prevention of disaggregation-induced mRNA decay by actinomycin D and daunomycin is therefore probably a secondary effect unrelated to the inhibition of transcription.

  19. Atherosclerotic Plaque Destabilization in Mice: A Comparative Study.

    Directory of Open Access Journals (Sweden)

    Helene Hartwig

    Full Text Available Atherosclerosis-associated diseases are the main cause of mortality and morbidity in western societies. The progression of atherosclerosis is a dynamic process evolving from early to advanced lesions that may become rupture-prone vulnerable plaques. Acute coronary syndromes are the clinical manifestation of life-threatening thrombotic events associated with high-risk vulnerable plaques. Hyperlipidemic mouse models have been extensively used in studying the mechanisms controlling initiation and progression of atherosclerosis. However, the understanding of mechanisms leading to atherosclerotic plaque destabilization has been hampered by the lack of proper animal models mimicking this process. Although various mouse models generate atherosclerotic plaques with histological features of human advanced lesions, a consensus model to study atherosclerotic plaque destabilization is still lacking. Hence, we studied the degree and features of plaque vulnerability in different mouse models of atherosclerotic plaque destabilization and find that the model based on the placement of a shear stress modifier in combination with hypercholesterolemia represent with high incidence the most human like lesions compared to the other models.

  20. Electrochemical and quantum chemical studies of N,N'-bis(4-hydroxybenzaldehyde)-2,2-dimethylpropandiimine Schiff base as corrosion inhibitor for low carbon steel in HCl solution.

    Science.gov (United States)

    Jafari, Hojat; Danaee, Iman; Eskandari, Hadi; Rashvandavei, Mehdi

    2013-01-01

    A synthesized Schiff base N,N'-bis(4-hydroxybenzaldehyde)-2,2-dimethylpropandiimine (p-HBDP) was studied as green inhibitor for the corrosion of low carbon steel in 1 M HCl solution using electrochemical, surface and quantum chemical methods. Results showed that the inhibition occurs through the adsorption of the inhibitor molecules on the metal surface. The inhibition efficiency was found to increase with increasing inhibitor concentration and de-creased with increasing temper-ature, which is due to the fact that the rate of corrosion of steel is higher than the rate of adsorption. Thermodynamic parameters for adsorp-tion and activation processes were determined. Polarization data indicated that this compound act as mixed-type inhibitors and the adsorption isotherm basically obeys the Langmuir adsorption isotherm. The calculations of reactivity indices of p-HBDP such as softness and natural charge distributions together with local reactivity by means of Fukui indices were used to explain the electron transfer mechanism between the p-HBDP molecules and the steel surface.

  1. Modeling Chemical Interaction Profiles: I. Spectral Data-Activity Relationship and Structure-Activity Relationship Models for Inhibitors and Non-inhibitors of Cytochrome P450 CYP3A4 and CYP2D6 Isozymes

    Directory of Open Access Journals (Sweden)

    Richard D. Beger

    2012-03-01

    Full Text Available An interagency collaboration was established to model chemical interactions that may cause adverse health effects when an exposure to a mixture of chemicals occurs. Many of these chemicals—drugs, pesticides, and environmental pollutants—interact at the level of metabolic biotransformations mediated by cytochrome P450 (CYP enzymes. In the present work, spectral data-activity relationship (SDAR and structure-activity relationship (SAR approaches were used to develop machine-learning classifiers of inhibitors and non-inhibitors of the CYP3A4 and CYP2D6 isozymes. The models were built upon 602 reference pharmaceutical compounds whose interactions have been deduced from clinical data, and 100 additional chemicals that were used to evaluate model performance in an external validation (EV test. SDAR is an innovative modeling approach that relies on discriminant analysis applied to binned nuclear magnetic resonance (NMR spectral descriptors. In the present work, both 1D 13C and 1D 15N-NMR spectra were used together in a novel implementation of the SDAR technique. It was found that increasing the binning size of 1D 13C-NMR and 15N-NMR spectra caused an increase in the tenfold cross-validation (CV performance in terms of both the rate of correct classification and sensitivity. The results of SDAR modeling were verified using SAR. For SAR modeling, a decision forest approach involving from 6 to 17 Mold2 descriptors in a tree was used. Average rates of correct classification of SDAR and SAR models in a hundred CV tests were 60% and 61% for CYP3A4, and 62% and 70% for CYP2D6, respectively. The rates of correct classification of SDAR and SAR models in the EV test were 73% and 86% for CYP3A4, and 76% and 90% for CYP2D6, respectively. Thus, both SDAR and SAR methods demonstrated a comparable performance in modeling a large set of structurally diverse data. Based on unique NMR structural descriptors, the new SDAR modeling method complements the existing SAR

  2. Risk assessment of mountain infrastructure destabilization in the French Alps

    Science.gov (United States)

    Duvillard, Pierre-Allain; Ravanel, Ludovic; Deline, Philip

    2015-04-01

    In the current context of imbalance of geosystems in connection with the rising air temperature for several decades, high mountain environments are especially affected by the shrinkage of glaciers and the permafrost degradation which can trigger slope movements in the rock slopes (rockfall, rock avalanches) or in superficial deposits (slides, rock glacier rupture, thermokarst). These processes generate a risk of direct destabilization for high mountain infrastructure (huts, cable-cars...) in addition to indirect risks for people and infrastructure located on the path of moving rock masses. We here focus on the direct risk of infrastructure destabilization due to permafrost degradation and/or glacier shrinkage in the French Alps. To help preventing these risks, an inventory of all the infrastructure was carried out with a GIS using different data layers among which the Alpine Permafrost Index Map and inventories of the French Alps glaciers in 2006-2009, 1967-1971 and at the end of the Little Ice Age. 1769 infrastructures have been identified in areas likely characterized by permafrost and/or possibly affected by glacier shrinkage. An index of risk of destabilization has been built to identify and to rank infrastructure at risk. This theoretical risk index includes a characterization of hazards and a diagnosis of the vulnerability. The value of hazard is dependent on passive factors (topography, lithology, geomorphological context...) and on so-considered active factors (thermal state of the permafrost, and changing constraints on slopes related to glacier shrinkage). The diagnosis of vulnerability has meanwhile been established by combining the level of potential damage to the exposed elements with their operational and financial values. The combination of hazard and vulnerability determines a degree of risk of infrastructure destabilization (from low to very high). Field work and several inventories of infrastructure damages were used to validate it. The

  3. Nano-engineering approach to destabilization of magnesium hydride (MgH2) by solid-state reaction with Si.

    Science.gov (United States)

    Bystrzycki, J; Polanski, M; Plocinski, T

    2009-06-01

    We studied a possibility of destabilization of MgH2 by chemical reaction with Si by using a nano-engineering method for reducing diffusion distances and increasing surface area. The structure, morphology, chemical composition and dehydriding properties were investigated by XRD, SEM, EDS, DTA-TG and the volumetric Sievert method. The commercial MgH2 and Si powder mixture corresponded to the stoichiometry of the ideal Mg2Si intermetallic compound was ball-milled under argon atmosphere to reach a nanocrystalline composite structure (MgH2-Si mixture leads to the formation only a small amount of the Mg2Si compound. Microstructural studies showed that Si after ball-milling is heterogeneously distributed on the surface of MgH2 particles and incorporated in the nanocrystalline MgH2 matrix, forming a nanocomposite structure. The sluggish destabilization of MgH2 by solid-state reaction with Si forming the Mg2Si intermetallic compound was observed at 250 degrees C. The XRD and EDS analysis confirmed that the Mg2Si compound is formed after the dehydrogenation of the synthesized MgH2-Si composite. The activation energy of the destabilization reaction for the investigated composite significantly decreased (162 kJ/mol) as compared with unmilled MgH2-Si powder mixture (213 kJ/mol).

  4. Use of mixtures containing nonionic surfactants in the destabilization of petroleum emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Mansur, Claudia R.E.; Mauro, Aparecida C.; Aquino, Aline S.; Lechuga, Fernanda C.; Gonzalez, Gaspar; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas; Gonzalez, Gaspar [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2004-07-01

    During the petroleum dehydration process, it is necessary to used chemical demulsifiers in order to break the w/o emulsions that are formed in the oil field. These demulsifiers products are, in many cases, surfactants based poly(ethylene oxide-propylene oxide) block copolymers (PEO-PPO), with different EO/PO molar ratio. In this work were correlate the structure and the properties of PEO-PPO block copolymers with their performance as petroleum emulsion-destabilizing agent. Moreover, it was used an additive in the formulations, known as hydrotrope, in order to increase the solubility of these copolymers in aqueous solution. The results showed that the copolymer branched, whose hydrophilic segments (PEO and OH) are in an external adjacent position, present the higher solubility, in spite of to own EO/PO ratio similar to the others copolymers and the highest molar mass. Moreover, this copolymer presented the best efficiency in the emulsion destabilization. The addition of the hydrotrope NaBMGS to the PEO-PPO copolymers aqueous solutions caused the solubility increasing of these compounds in water. Such additive being used in the demulsifier formulation provoked an efficiency improving on the emulsion breaking process. (author)

  5. Genomic mechanisms of stress tolerance for the industrial yeast Saccharomyces cerevisiae against major chemical classes of inhibitors

    Science.gov (United States)

    Numerous toxic chemical compounds liberated from lignocellulosic biomass pretreatment inhibit subsequent microbial fermentation that pose a significant challenge to a sustainable and renewable bio-based fermentation industry. Toxin removal procedures by physical or chemical means are essentially imp...

  6. Extracellular α-synuclein leads to microtubule destabilization via GSK-3β-dependent Tau phosphorylation in PC12 cells.

    Directory of Open Access Journals (Sweden)

    Magdalena Gąssowska

    Full Text Available α-Synuclein (ASN plays an important role in pathogenesis of Parkinson's disease (PD and other neurodegenerative disorders. Novel and most interesting data showed elevated tauopathy in PD and suggested relationship between ASN and Tau protein. However, the mechanism of ASN-evoked Tau protein modification is not fully elucidated. In this study we investigated the role of extracellular ASN in Tau hyperphosphorylation in rat pheochromocytoma (PC12 cells and the involvement of glycogen synthase kinase-3β (GSK-3β and cyclin-dependent kinase 5 (CDK5 in ASN-dependent Tau modification. Our results indicated that exogenously added ASN increases Tau phosphorylation at Ser396. Accordingly, the GSK-3β inhibitor (SB-216763 prevented ASN-evoked Tau hyperphosphorylation, but the CDK5 inhibitor had no effect. Moreover, western blot analysis showed that ASN affected GSK-3β via increasing of protein level and activation of this enzyme. GSK-3β activity evaluated by its phosphorylation status assay showed that ASN significantly increased the phosphorylation of this enzyme at Tyr216 with parallel decrease in phosphorylation at Ser9, indicative of stimulation of GSK-3β activity. Moreover, the effect of ASN on microtubule (MT destabilization and cell death with simultaneous the involvement of GSK-3β in these processes were analyzed. ASN treatment increased the amount of free tubulin and concomitantly reduced the amount of polymerized tubulin and SB-216763 suppressed these ASN-induced changes in tubulin, indicating that GSK-3β is involved in ASN-evoked MT destabilization. ASN-induced apoptotic processes lead to decrease in PC12 cells viability and SB-216763 protected those cells against ASN-evoked cytotoxicity. Concluding, extracellular ASN is involved in GSK-3β-dependent Tau hyperphosphorylation, which leads to microtubule destabilization. GSK-3β inhibition may be an effective strategy for protecting against ASN-induced cytotoxicity.

  7. Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions.

    Science.gov (United States)

    Dibetsoe, Masego; Olasunkanmi, Lukman O; Fayemi, Omolola E; Yesudass, Sasikumar; Ramaganthan, Baskar; Bahadur, Indra; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-08-28

    The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs) namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1), 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (Pc2), 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3) and 29H,31H-phthalocyanine (Pc4), and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1), 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2) and 2,3-naphthalocyanine (nP3) were investigated on the corrosion of aluminium (Al) in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR). Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I(-) ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR analysis on the

  8. Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions

    Directory of Open Access Journals (Sweden)

    Masego Dibetsoe

    2015-08-01

    Full Text Available The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1, 2,3,9,10,16,17,23,24-octakis(octyloxy-29H,31H-phthalocyanine (Pc2, 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3 and 29H,31H-phthalocyanine (Pc4, and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1, 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2 and 2,3-naphthalocyanine (nP3 were investigated on the corrosion of aluminium (Al in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR. Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I− ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR

  9. An Investigation of a Combined Thiourea and Hexamethylenetetramine as Inhibitors for Corrosion of N80 in 15% HCl Solution: Electrochemical Experiments and Quantum Chemical Calculation

    Directory of Open Access Journals (Sweden)

    Jun Hu

    2015-01-01

    Full Text Available The inhibition mechanism of thiourea (TU and hexamethylenetetramine (HMTA mixed in 15% HCl solution on N80 surface was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy measurements, and surface morphology analysis. Quantum chemical calculations and molecular dynamics simulations were performed to study the properties of TU and HMTA. The results showed that the inhibitors can form strong bonds and stable films on the surface, which inhibits the cathodic and anodic reactions in HCl solution and reduces the diffusion coefficients of corrosive particles.

  10. Unfolding Ubiquitin by force: water mediated H-bond destabilization

    Directory of Open Access Journals (Sweden)

    Germán Pabón

    2012-12-01

    Full Text Available Using the “pull and wait” (PNW simulation protocol at 300 K, we studied the unfolding by force of an ubiquitin molecule. PNW was implemented in the CHARMM program using an integration time step of 1 fs and a uniform dielectric constant of 1. The ubiquitin molecule, initially solvated, was put under mechanical stress, exerting forces from different directions. The rupture of five hydrogen bonds between parallel strands β1 and β5 takes place during the extension from 13 to 15 Å, defines a mechanical barrier for unfolding and dominates the point of maximum unfolding force. The simulations described here show that given adequate time, a small applied force can destabilize those five H-bonds relative to the bonds that can be created to water molecules; allowing the formation of stable H-bonds between a single water molecule and the donor and acceptor groups of the interstrand H-bonds. Thus, simulations run with PNW show that the force is not responsible for “ripping apart” the backbone H-bonds; it merely destabilizes them making them less stable than the H-bonds they can make with water. Additional simulations show that the force necessary to destabilize the H-bonds and allow them to be replaced by H-bonds to water molecules depends strongly on the pulling direction. By using a simulation protocol that allows equilibration at each extension we have been able to observe the details of the events leading to the unfolding of ubiquitin by mechanical force.

  11. Trapped particle destabilization of the internal kink mode

    Energy Technology Data Exchange (ETDEWEB)

    White, R.B.; Chen, L.; Romanelli, F.; Hay, R.

    1984-06-01

    The internal kink mode is destabilized by trapped high energy particles, leading to a new branch of the internal kink dispersion relation with a real frequency near the average trapped particle precession frequency and a growth rate of the same magnitude. This trapped particle branch of the dispersion relation is investigated numerically for a variety of particle distributions. Mode growth rate and frequency are found as a function of plasma ..beta.., density, and trapped particle energy and distribution. The high energy trapped particle sources considered are neutral beam injection, ion cyclotron heating, and fusion alpha particles. Relevance for various plasma heating schemes is discussed.

  12. Insight into the effect of inhibitor resistant S130G mutant on physico-chemical properties of SHV type beta-lactamase: a molecular dynamics study.

    Directory of Open Access Journals (Sweden)

    Mohd Hassan Baig

    Full Text Available Bacterial resistance is a serious threat to human health. The production of β-lactamase, which inactivates β-lactams is most common cause of resistance to the β-lactam antibiotics. The Class A enzymes are most frequently encountered among the four β-lactamases in the clinic isolates. Mutations in class A β-lactamases play a crucial role in substrate and inhibitor specificity. SHV and TEM type are known to be most common class A β-lactamases. In the present study, we have analyzed the effect of inhibitor resistant S130G point mutation of SHV type Class-A β-lactamase using molecular dynamics and other in silico approaches. Our study involved the use of different in silico methods to investigate the affect of S130G point mutation on the major physico-chemical properties of SHV type class A β-lactamase. We have used molecular dynamics approach to compare the dynamic behaviour of native and S130G mutant form of SHV β-lactamase by analyzing different properties like root mean square deviation (RMSD, H-bond, Radius of gyration (Rg and RMS fluctuation of mutation. The results clearly suggest notable loss in the stability of S130G mutant that may further lead to decrease in substrate specificity of SHV. Molecular docking further indicates that S130G mutation decreases the binding affinity of all the three inhibitors in clinical practice.

  13. Discovery of New Chemical Entities for Old Targets: Insights on the Lead Optimization of Chromone-Based Monoamine Oxidase B (MAO-B) Inhibitors.

    Science.gov (United States)

    Reis, Joana; Cagide, Fernando; Chavarria, Daniel; Silva, Tiago; Fernandes, Carlos; Gaspar, Alexandra; Uriarte, Eugenio; Remião, Fernando; Alcaro, Stefano; Ortuso, Francesco; Borges, Fernanda

    2016-06-23

    The discovery of new chemical entities endowed with potent, selective, and reversible monoamine oxidase B inhibitory activity is a clinically relevant subject. Therefore, a small library of chromone derivatives was synthesized and screened toward human monoamine oxidase isoforms (hMAO-A and hMAO-B). The structure-activity relationships studies strengthen the importance of the amide spacer and the direct linkage of carbonyl group to the γ-pyrone ring, along with the presence of meta and para substituents in the exocyclic ring. The most potent MAO-B inhibitors were N-(3'-chlorophenyl)-4-oxo-4H-chromene-3-carboxamide (20) (IC50 = 403 pM) and N-(3',4'-dimethylphenyl)-4-oxo-4H-chromene-3-carboxamide (27) (IC50 = 669 pM), acting as competitive and noncompetitive reversible inhibitors, respectively. Computational docking studies provided insights into enzyme-inhibitor interactions and a rationale for the observed selectivity and potency. Compound 27 stands out due to its favorable toxicological profile and physicochemical properties, which pointed toward blood-brain barrier permeability, thus being a valid candidate for subsequent animal studies.

  14. Hydrazine borane-induced destabilization of ammonia borane, and vice versa

    Energy Technology Data Exchange (ETDEWEB)

    Petit, Jean-Fabien; Moussa, Georges [IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon, F-34095 Montpellier (France); Demirci, Umit B., E-mail: umit.demirci@um2.fr [IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon, F-34095 Montpellier (France); Toche, François; Chiriac, Rodica [Université Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France); Miele, Philippe [IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon, F-34095 Montpellier (France)

    2014-08-15

    Graphical abstract: - Highlights: • Hydrazine borane and ammoniaborane (mole ratio 1:1) destabilize each other. • This is characterized by a melting point at ∼30 °C and decomposition into hydrazine. • Also, some hydrogen H{sub 2} is “explosively” liberated at around 90 °C. • The mixture can be however stabilized into a potential hydrogen storage material. • This hydrogen storage material dehydrogenates up to 300 °C to form boron nitride. - Abstract: In the field of solid-state chemical hydrogen storage, ammonia borane NH{sub 3}BH{sub 3} has been widely studied while hydrazine borane N{sub 2}H{sub 4}BH{sub 3} can be considered as a “novel” material. In the present work, we investigated the behaviour of these boranes when mixed together in a mole ratio of 1:1. Hydrazine borane and ammonia borane destabilize each other. Though stable at 20–25 °C, the mixture melts at ∼30 °C and then undergoes significant decomposition, with desorption of hydrogen H{sub 2} and hydrazine N{sub 2}H{sub 4} from 67 °C. This is explained by the fact that the presence of hydrazine borane disrupts the H{sup δ+}⋯H{sup δ−} network of ammonia borane, and vice versa; the mixture is then much less stable than the pristine boranes. The mixture can nevertheless be stabilized (by heat- or vacuum-treatment and thus extraction of evolving hydrogen and hydrazine), making the as-obtained solid a potential chemical hydrogen storage material. Over the range 25–300 °C, it is able to release ca. 11.4 wt% of almost pure H{sub 2}. Furthermore forms boron nitride as the solid residue, at temperatures as low as 300 °C.

  15. Dramatic destabilization of the Ru(0001) surface upon oxygen adsorption

    Science.gov (United States)

    Reuter, K.; Ganduglia-Pirovano, M. V.; Scheffler, M.; Stampfl, C.

    2000-03-01

    Under high oxygen pressures, where most other transition metal surfaces typically form inert surface oxides, Ru(0001) displays the highest rates for oxidation reactions. This unusual behavior has been attributed to the fact that Ru can exist in different oxidation states and to the ease with which its surface can be loaded with high concentrations of subsurface oxygen. Yet, recent experiments have also indicated that high oxygen loads in the subsurface region destabilize Ru(0001) and lead to the emission of RuOx (xA. Böttcher, H. Conrad and H. Niehus, J. Chem. Phys. (submitted).). We perform density functional theory calculations to gain a fundamental understanding of the O-Ru bond in on-surface as well as subsurface oxygen phases. After completion of a full monolayer coverage on the surface, Ru(0001) is found to strongly bind even up to another full monolayer in the sites directly below the first substrate layer. In agreement with the experimental findings, this highly loaded O-Ru-O fringe is then relatively instable against lift-off, which might lead to either RuOx fragmentation or restructuring. The relation between charge transfer towards the oxygen and bond formation, as well as substrate destabilization is discussed.

  16. Destabilization of confined granular packings due to fluid flow

    Science.gov (United States)

    Monloubou, Martin; Sandnes, Bjørnar

    2016-04-01

    Fluid flow through granular materials can cause fluidization when fluid drag exceeds the frictional stress within the packing. Fluid driven failure of granular packings is observed in both natural and engineered settings, e.g. soil liquefaction and flowback of proppants during hydraulic fracturing operations. We study experimentally the destabilization and flow of an unconsolidated granular packing subjected to a point source fluid withdrawal using a model system consisting of a vertical Hele-Shaw cell containing a water-grain mixture. The fluid is withdrawn from the cell at a constant rate, and the emerging flow patterns are imaged in time-lapse mode. Using Particle Image Velocimetry (PIV), we show that the granular flow gets localized in a narrow channel down the center of the cell, and adopts a Gaussian velocity profile similar to those observed in dry grain flows in silos. We investigate the effects of the experimental parameters (flow rate, grain size, grain shape, fluid viscosity) on the packing destabilization, and identify the physical mechanisms responsible for the observed complex flow behaviour.

  17. Experimental and quantum chemical studies on two triazole derivatives as corrosion inhibitors for mild steel in acid media

    Energy Technology Data Exchange (ETDEWEB)

    Li, W.; Tian, H.; Hou, B. [Key Laboratory of Corrosion Science, Shandong, Institute of Oceanology, Chinese Academy of Sciences, Qingdao (China); Hu, L.; Tao, Z. [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing (China)

    2011-11-15

    Two triazole derivatives [1-phenyl-2-(5-(1,2,4) triazol-1-ylmethyl-(1,3,4) oxadizaol-2-ylsulphanyl)-ethanone (PTOE) and 2-(4-tert-butyl-benzylsulphanyl)-5-(1,2,4) triazol-1-ylmethyl-(1,3,4) oxadiazole (TBTO)] were synthesized as new corrosion inhibitors for the corrosion of mild steel in 1 M hydrochloric acid solutions. The inhibiting efficiency of the different inhibitors was evaluated by means of weight loss and electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and polarization curves. The electrochemical investigation results indicate that these compounds act as mixed-type inhibitors retarding the anodic and cathodic corrosion reactions and do not change the mechanism of either hydrogen evolution reaction or mild steel dissolution. The studied compounds followed the Langmuir adsorption isotherm, and the thermodynamic parameters were determined and discussed. The effect of molecular structure on the inhibition efficiency has been investigated with ab initio calculations. The electronic properties such as highest occupied molecular orbital (HOMO) energy level, lowest unoccupied molecular orbital (LUMO) energy level, dipole moment ({mu}) and molecular orbital densities were calculated. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Phenotype-based high-content chemical library screening identifies statins as inhibitors of in vivo lymphangiogenesis.

    Science.gov (United States)

    Schulz, Martin Michael Peter; Reisen, Felix; Zgraggen, Silvana; Fischer, Stephanie; Yuen, Don; Kang, Gyeong Jin; Chen, Lu; Schneider, Gisbert; Detmar, Michael

    2012-10-02

    Lymphangiogenesis plays an important role in promoting cancer metastasis to sentinel lymph nodes and beyond and also promotes organ transplant rejection. We used human lymphatic endothelial cells to establish a reliable three-dimensional lymphangiogenic sprouting assay with automated image acquisition and analysis for inhibitor screening. This high-content phenotype-based assay quantifies sprouts by automated fluorescence microscopy and newly developed analysis software. We identified signaling pathways involved in lymphangiogenic sprouting by screening the Library of Pharmacologically Active Compounds (LOPAC)(1280) collection of pharmacologically relevant compounds. Hit characterization revealed that mitogen-activated protein kinase kinase (MEK) 1/2 inhibitors substantially block lymphangiogenesis in vitro and in vivo. Importantly, the drug class of statins, for the first time, emerged as potent inhibitors of lymphangiogenic sprouting in vitro and of corneal and cutaneous lymphangiogenesis in vivo. This effect was mediated by inhibition of the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and subsequently the isoprenylation of Rac1. Supplementation with the enzymatic products of HMG-CoA reductase functionally rescued lymphangiogenic sprouting and the recruitment of Rac1 to the plasma membrane.

  19. Investigation on the isoform selectivity of novel kinesin-like protein 1 (KIF11) inhibitor using chemical feature based pharmacophore, molecular docking, and quantum mechanical studies.

    Science.gov (United States)

    Karunagaran, Subramanian; Subhashchandrabose, Subramaniyan; Lee, Keun Woo; Meganathan, Chandrasekaran

    2016-04-01

    Kinesin-like protein (KIF11) is a molecular motor protein that is essential in mitosis. Removal of KIF11 prevents centrosome migration and causes cell arrest in mitosis. KIF11 defects are linked to the disease of microcephaly, lymph edema or mental retardation. The human KIF11 protein has been actively studied for its role in mitosis and its potential as a therapeutic target for cancer treatment. Pharmacophore modeling, molecular docking and density functional theory approaches was employed to reveal the structural, chemical and electronic features essential for the development of small molecule inhibitor for KIF11. Hence we have developed chemical feature based pharmacophore models using Discovery Studio v 2.5 (DS). The best hypothesis (Hypo1) consisting of four chemical features (two hydrogen bond acceptor, one hydrophobic and one ring aromatic) has exhibited high correlation co-efficient of 0.9521, cost difference of 70.63 and low RMS value of 0.9475. This Hypo1 is cross validated by Cat Scramble method; test set and decoy set to prove its robustness, statistical significance and predictability respectively. The well validated Hypo1 was used as 3Dquery to perform virtual screening. The hits obtained from the virtual screening were subjected to various scrupulous drug-like filters such as Lipinski's rule of five and ADMET properties. Finally, six hit compounds were identified based on the molecular interaction and its electronic properties. Our final lead compound could serve as a powerful tool for the discovery of potent inhibitor as KIF11 agonists.

  20. Chemical genetics screen for enhancers of rapamycin identifies a specific inhibitor of an SCF family E3 ubiquitin ligase.

    Science.gov (United States)

    Aghajan, Mariam; Jonai, Nao; Flick, Karin; Fu, Fei; Luo, Manlin; Cai, Xiaolu; Ouni, Ikram; Pierce, Nathan; Tang, Xiaobo; Lomenick, Brett; Damoiseaux, Robert; Hao, Rui; Del Moral, Pierre M; Verma, Rati; Li, Ying; Li, Cheng; Houk, Kendall N; Jung, Michael E; Zheng, Ning; Huang, Lan; Deshaies, Raymond J; Kaiser, Peter; Huang, Jing

    2010-07-01

    The target of rapamycin (TOR) plays a central role in eukaryotic cell growth control. With prevalent hyperactivation of the mammalian TOR (mTOR) pathway in human cancers, strategies to enhance TOR pathway inhibition are needed. We used a yeast-based screen to identify small-molecule enhancers of rapamycin (SMERs) and discovered an inhibitor (SMER3) of the Skp1-Cullin-F-box (SCF)(Met30) ubiquitin ligase, a member of the SCF E3-ligase family, which regulates diverse cellular processes including transcription, cell-cycle control and immune response. We show here that SMER3 inhibits SCF(Met30) in vivo and in vitro, but not the closely related SCF(Cdc4). Furthermore, we demonstrate that SMER3 diminishes binding of the F-box subunit Met30 to the SCF core complex in vivo and show evidence for SMER3 directly binding to Met30. Our results show that there is no fundamental barrier to obtaining specific inhibitors to modulate function of individual SCF complexes.

  1. A mechanism for dust-induced destabilization of glacial climates

    Directory of Open Access Journals (Sweden)

    B. F. Farrell

    2012-05-01

    Full Text Available Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate qualitatively glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle.

  2. A mechanism for dust-induced destabilization of glacial climates

    Directory of Open Access Journals (Sweden)

    B. F. Farrell

    2012-12-01

    Full Text Available Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle.

  3. Destabilizing Tachyonic Vacua at or above the BF Bound

    CERN Document Server

    Kanno, Sugumi; Soda, Jiro

    2012-01-01

    It is well known that tachyonic vacua in an asymptotically Anti-de Sitter (AdS) space-time are classically stable if the mass squared is at or above the Breitenlohner and Freedman (BF) bound. We study the quantum stability of these tachyonic vacua in terms of instantons. We find a series of exact instanton solutions destabilizing tachyonic state at or above the BF bound in asymptotically AdS space. We also give an analytic formula for the decay rate and show that it is finite. Comparing our result with the well-known algebraic condition for the stability, we discuss stability conditions of tachyonic vacua at or above the BF bound.

  4. Nutrient flows between ecosystems can destabilize simple food chains.

    Science.gov (United States)

    Marleau, Justin N; Guichard, Frédéric; Mallard, François; Loreau, Michel

    2010-09-07

    Dispersal of organisms has large effects on the dynamics and stability of populations and communities. However, current metacommunity theory largely ignores how the flows of limiting nutrients across ecosystems can influence communities. We studied a meta-ecosystem model where two autotroph-consumer communities are spatially coupled through the diffusion of the limiting nutrient. We analyzed regional and local stability, as well as spatial and temporal synchrony to elucidate the impacts of nutrient recycling and diffusion on trophic dynamics. We show that nutrient diffusion is capable of inducing asynchronous local destabilization of biotic compartments through a diffusion-induced spatiotemporal bifurcation. Nutrient recycling interacts with nutrient diffusion and influences the susceptibility of the meta-ecosystem to diffusion-induced instabilities. This interaction between nutrient recycling and transport is further shown to depend on ecosystem enrichment. It more generally emphasizes the importance of meta-ecosystem theory for predicting species persistence and distribution in managed ecosystems.

  5. Allosteric Inhibition via R-state Destabilization in ATP Sulfurylase from Penicillium chrysogenum

    Energy Technology Data Exchange (ETDEWEB)

    MacRae, I. J.

    2002-01-01

    The structure of the cooperative hexameric enzyme ATP sulfurylase from Penicillium chrysogenum bound to its allosteric inhibitor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS), was determined to 2.6 {angstrom} resolution. This structure represents the low substrate-affinity T-state conformation of the enzyme. Comparison with the high substrate-affinity R-state structure reveals that a large rotational rearrangement of domains occurs as a result of the R-to-T transition. The rearrangement is accompanied by the 17 {angstrom} movement of a 10-residue loop out of the active site region, resulting in an open, product release-like structure of the catalytic domain. Binding of PAPS is proposed to induce the allosteric transition by destabilizing an R-state-specific salt linkage between Asp 111 in an N-terminal domain of one subunit and Arg 515 in the allosteric domain of a trans-triad subunit. Disrupting this salt linkage by site-directed mutagenesis induces cooperative inhibition behavior in the absence of an allosteric effector, confirming the role of these two residues.

  6. SLAP displays tumour suppressor functions in colorectal cancer via destabilization of the SRC substrate EPHA2

    Science.gov (United States)

    Naudin, Cécile; Sirvent, Audrey; Leroy, Cédric; Larive, Romain; Simon, Valérie; Pannequin, Julie; Bourgaux, Jean-François; Pierre, Josiane; Robert, Bruno; Hollande, Frédéric; Roche, Serge

    2014-01-01

    The adaptor SLAP is a negative regulator of receptor signalling in immune cells but its role in human cancer is ill defined. Here we report that SLAP is abundantly expressed in healthy epithelial intestine but strongly downregulated in 50% of colorectal cancer. SLAP overexpression suppresses cell tumorigenicity and invasiveness while SLAP silencing enhances these transforming properties. Mechanistically, SLAP controls SRC/EPHA2/AKT signalling via destabilization of the SRC substrate and receptor tyrosine kinase EPHA2. This activity is independent from CBL but requires SLAP SH3 interaction with the ubiquitination factor UBE4A and SLAP SH2 interaction with pTyr594-EPHA2. SRC phosphorylates EPHA2 on Tyr594, thus creating a feedback loop that promotes EPHA2 destruction and thereby self-regulates its transforming potential. SLAP silencing enhances SRC oncogenicity and sensitizes colorectal tumour cells to SRC inhibitors. Collectively, these data establish a tumour-suppressive role for SLAP in colorectal cancer and a mechanism of SRC oncogenic induction through stabilization of its cognate substrates.

  7. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  8. Therapeutic potential of proteasome inhibitors in congenital erythropoietic porphyria.

    Science.gov (United States)

    Blouin, Jean-Marc; Duchartre, Yann; Costet, Pierre; Lalanne, Magalie; Ged, Cécile; Lain, Ana; Millet, Oscar; de Verneuil, Hubert; Richard, Emmanuel

    2013-11-05

    Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disorder characterized by uroporphyrinogen III synthase (UROS) deficiency resulting in massive porphyrin accumulation in blood cells, which is responsible for hemolytic anemia and skin photosensitivity. Among the missense mutations actually described up to now in CEP patients, the C73R and the P248Q mutations lead to a profound UROS deficiency and are usually associated with a severe clinical phenotype. We previously demonstrated that the UROS(C73R) mutant protein conserves intrinsic enzymatic activity but triggers premature degradation in cellular systems that could be prevented by proteasome inhibitors. We show evidence that the reduced kinetic stability of the UROS(P248Q) mutant is also responsible for increased protein turnover in human erythroid cells. Through the analysis of EGFP-tagged versions of UROS enzyme, we demonstrate that both UROS(C73R) and UROS(P248Q) are equally destabilized in mammalian cells and targeted to the proteasomal pathway for degradation. We show that a treatment with proteasomal inhibitors, but not with lysosomal inhibitors, could rescue the expression of both EGFP-UROS mutants. Finally, in CEP mice (Uros(P248Q/P248Q)) treated with bortezomib (Velcade), a clinically approved proteasome inhibitor, we observed reduced porphyrin accumulation in circulating RBCs and urine, as well as reversion of skin photosensitivity on bortezomib treatment. These results of medical importance pave the way for pharmacologic treatment of CEP disease by preventing certain enzymatically active UROS mutants from early degradation by using proteasome inhibitors or chemical chaperones.

  9. MDMA induces cardiac contractile dysfunction through autophagy upregulation and lysosome destabilization in rats.

    Science.gov (United States)

    Shintani-ishida, Kaori; Saka, Kanju; Yamaguchi, Koji; Hayashida, Makiko; Nagai, Hisashi; Takemura, Genzou; Yoshida, Ken-ichi

    2014-05-01

    The underlying mechanisms of cardiotoxicity of 3,4-methylenedioxymethylamphetamine (MDMA, "ecstasy") abuse are unclear. Autophagy exerts either adaptive or maladaptive effects on cardiac function in various pathological settings, but nothing is known on the role of autophagy in the MDMA cardiotoxicity. Here, we investigated the mechanism through which autophagy may be involved in MDMA-induced cardiac contractile dysfunction. Rats were injected intraperitoneally with MDMA (20mg/kg) or saline. Left ventricular (LV) echocardiography and LV pressure measurement demonstrated reduction of LV systolic contractility 24h after MDMA administration. Western blot analysis showed a time-dependent increase in the levels of microtubule-associated protein light chain 3-II (LC3-II) and cathepsin-D after MDMA administration. Electron microscopy showed the presence of autophagic vacuoles in cardiomyocytes. MDMA upregulated phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) at Thr172, mammalian target of rapamycin (mTOR) at Thr2446, Raptor at Ser792, and Unc51-like kinase (ULK1) at Ser555, suggesting activation of autophagy through the AMPK-mTOR pathway. The effects of autophagic inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) on LC3-II levels indicated that MDMA enhanced autophagosome formation, but attenuated autophagosome clearance. MDMA also induced release of cathepsins into cytosol, and western blotting and electron microscopy showed cardiac troponin I (cTnI) degradation and myofibril damage, respectively. 3-MA, CQ, and a lysosomal inhibitor, E64c, inhibited cTnI proteolysis and improved contractile dysfunction after MDMA administration. In conclusion, MDMA causes lysosome destabilization following activation of the autophagy-lysosomal pathway, through which released lysosomal proteases damage myofibrils and induce LV systolic dysfunction in rat heart.

  10. Development of nanoparticles incorporating a novel liposomal membrane destabilization peptide for efficient release of cargos into cancer cells.

    Directory of Open Access Journals (Sweden)

    Shoko Itakura

    Full Text Available In anti-cancer therapy mediated by a nanoparticle-based drug delivery system (DDS, overall efficacy depends on the release efficiency of cargos from the nanoparticles in the cancer cells as well as the specificity of delivery to tumor tissue. However, conventional liposome-based DDS have no mechanism for specifically releasing the encapsulated cargos inside the cancer cells. To overcome this barrier, we developed nanoparticles containing a novel liposomal membrane destabilization peptide (LMDP that can destabilize membranes by cleavage with intramembranous proteases on/in cancer cells. Calcein encapsulated in liposomes modified with LMDP (LMDP-lipo was effectively released in the presence of a membrane fraction containing an LMDP-cleavable protease. The release was inhibited by a protease inhibitor, suggesting that LMDP-lipo could effectively release its cargo into cells in response to a cancer-specific protease. Moreover, when LMDP-lipo contained fusogenic lipids, the release of cargo was accelerated, suggesting that the fusion of LMDP-lipo with cellular membranes was the initial step in the intracellular delivery. Time-lapse microscopic observations showed that the release of cargo from LMDP-lipo occurred immediately after association of LMDP-lipo with target cells. Consequently, LMDP-lipo could be a useful nanoparticle capable of effective release of cargos specifically into targeted cancer cells.

  11. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies.

    Science.gov (United States)

    Singh, Ambrish; Lin, Yuanhua; Quraishi, Mumtaz A; Olasunkanmi, Lukman O; Fayemi, Omolola E; Sasikumar, Yesudass; Ramaganthan, Baskar; Bahadur, Indra; Obot, Ime B; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-08-18

    The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (HPTB), 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin (T4PP), 4,4',4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrakis(benzoic acid) (THP) and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP) was studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM) techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR) were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  12. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

    Directory of Open Access Journals (Sweden)

    Ambrish Singh

    2015-08-01

    Full Text Available The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphyrin (HPTB, 5,10,15,20-tetra(4-pyridyl-21H,23H-porphyrin (T4PP, 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayltetrakis(benzoic acid (THP and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP was studied using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization, scanning electrochemical microscopy (SECM and scanning electron microscopy (SEM techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  13. Reversal of a full-length mutant huntingtin neuronal cell phenotype by chemical inhibitors of polyglutamine-mediated aggregation

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    MacDonald Marcy E

    2005-01-01

    Full Text Available Abstract Background Huntington's disease (HD is an inherited neurodegenerative disorder triggered by an expanded polyglutamine tract in huntingtin that is thought to confer a new conformational property on this large protein. The propensity of small amino-terminal fragments with mutant, but not wild-type, glutamine tracts to self-aggregate is consistent with an altered conformation but such fragments occur relatively late in the disease process in human patients and mouse models expressing full-length mutant protein. This suggests that the altered conformational property may act within the full-length mutant huntingtin to initially trigger pathogenesis. Indeed, genotype-phenotype studies in HD have defined genetic criteria for the disease initiating mechanism, and these are all fulfilled by phenotypes associated with expression of full-length mutant huntingtin, but not amino-terminal fragment, in mouse models. As the in vitro aggregation of amino-terminal mutant huntingtin fragment offers a ready assay to identify small compounds that interfere with the conformation of the polyglutamine tract, we have identified a number of aggregation inhibitors, and tested whether these are also capable of reversing a phenotype caused by endogenous expression of mutant huntingtin in a striatal cell line from the HdhQ111/Q111 knock-in mouse. Results We screened the NINDS Custom Collection of 1,040 FDA approved drugs and bioactive compounds for their ability to prevent in vitro aggregation of Q58-htn 1–171 amino terminal fragment. Ten compounds were identified that inhibited aggregation with IC50 HdhQ111/Q111 striatal cells. Conclusions At least some compounds identified as aggregation inhibitors also prevent a neuronal cellular phenotype caused by full-length mutant huntingtin, suggesting that in vitro fragment aggregation can act as a proxy for monitoring the disease-producing conformational property in HD. Thus, identification and testing of compounds that

  14. Involvement of Protein Phosphatases in the Destabilization of Methamphetamine-Associated Contextual Memory

    Science.gov (United States)

    Yu, Yang-Jung; Huang, Chien-Hsuan; Chang, Chih-Hua; Gean, Po-Wu

    2016-01-01

    Destabilization refers to a memory that becomes unstable when reactivated and is susceptible to disruption by amnestic agents. Here we delineated the cellular mechanism underlying the destabilization of drug memory. Mice were conditioned with methamphetamine (MeAM) for 3 d, and drug memory was assessed with a conditioned place preference (CPP)…

  15. Quantum Chemical Calculations and Molecular Docking Studies of Some NSAID Drugs (Aceclofenac, Salicylic Acid, and Piroxicam as 1PGE Inhibitors

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    S. Suresh

    2016-01-01

    Full Text Available The molecular structure of the three compounds Aceclofenac (I, Salicylic Acid (II, and Piroxicam (III has been determined using Gaussian 03W program with B3LYP method using 6-311++G (d,p basis set calculations. The molecular structures were fully optimized with atomic numbering scheme adopted in the study. To understand the mode of binding and molecular interaction, the docking studies of compounds Aceclofenac (I, Salicylic Acid (II, and Piroxicam (III have been carried out with prostaglandin H2 synthase-1 (1PGE as target using induced fit docking. The molecular docking results show that the interactions and energy for Aceclofenac, Salicylic Acid, and Piroxicam show the best results when docked with prostaglandin H2 synthase-1 (1PGE. The hydrogen bonding interactions of compound I (Aceclofenac are prominent with Arginine moiety, those of compound II (Salicylic Acid are prominent with Tyrosine and Serine moieties, and compound III (Piroxicam shows such interaction with Tyrosine and Arginine moieties. These interactions of prostaglandin H2 synthase-1 (1PGE with substrates are responsible for governing COX-1 inhibitor potency which in turn is a direct measure of the potency of the drug.

  16. A Synergistic Combination of Advanced Separation and Chemical Scale Inhibitor Technologies for Efficient Use of Imparied Water As Cooling Water in Coal-based Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Jasbir Gill

    2010-08-30

    /silicate are two common potential cycle-limiting minerals for using impaired waters. For produced waters, barium sulfate and calcium sulfate are two additional potential cycle-limiting minerals. For reclaimed municipal wastewater effluents, calcium phosphate scaling can be an issue, especially in the co-presence of high silica. Computational assessment, using a vast amount of Nalco's field data from coal fired power plants, showed that the limited use and reuse of impaired waters is due to the formation of deposit caused by the presence of iron, high hardness, high silica and high alkalinity in the water. Appropriate and cost-effective inhibitors were identified and developed - LL99B0 for calcite and gypsum inhibition and TX-15060 for silica inhibition. Nalco's existing dispersants HSP-1 and HSP-2 has excellent efficacy for dispersing Fe and Mn. ED and EDI were bench-scale tested by the CRADA partner Argonne National Laboratory for hardness, alkalinity and silica removal from synthetic make-up water and then cycled cooling water. Both systems showed low power consumption and 98-99% salt removal, however, the EDI system required 25-30% less power for silica removal. For Phase 2, the EDI system's performance was optimized and the length of time between clean-in-place (CIP) increased by varying the wafer composition and membrane configuration. The enhanced EDI system could remove 88% of the hardness and 99% of the alkalinity with a processing flux of 19.2 gal/hr/m{sup 2} and a power consumption of 0.54 kWh/100 gal water. Bench tests to screen alternative silica/silicate scale inhibitor chemistries have begun. The silica/silicate control approaches using chemical inhibitors include inhibition of silicic acid polymerization and dispersion of silica/silicate crystals. Tests were conducted with an initial silica concentration of 290-300 mg/L as SiO{sub 2} at pH 7 and room temperature. A proprietary new chemistry was found to be promising, compared with a current

  17. Control of Hes7 expression by Tbx6, the Wnt pathway and the chemical Gsk3 inhibitor LiCl in the mouse segmentation clock.

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    Aitor González

    Full Text Available The mouse segmentation is established from somites, which are iteratively induced every two hours from the presomitic mesoderm (PSM by a system known as the segmentation clock. A crucial component of the segmentation clock is the gene Hes7, which is regulated by the Notch and Fgf/Mapk pathways, but its relation to other pathways is unknown. In addition, chemical alteration of the Wnt pathway changes the segmentation clock period but the mechanism is unclear.To clarify these questions, we have carried out Hes7 promoter analysis in transgenic mouse embryos and have identified an essential 400 bp region, which contains binding sites of Tbx6 and the Wnt signaling effector Lef1. We have found that the Hes7 promoter is activated by Tbx6, and normal activity of the Hes7 promoter in the mouse PSM requires Tbx6 binding sites. Our results demonstrate that Wnt pathway molecules activate the Hes7 promoter cooperatively with Tbx6 in cell culture and are necessary for its proper expression in the mouse PSM. Furthermore, it is shown that the chemical Gsk3 inhibitor LiCl lengthens the oscillatory period of Hes7 promoter activity.Our data suggest that Tbx6 and the Wnt pathway cooperatively regulate proper Hes7 expression. Furthermore, proper Hes7 promoter activity and expression is important for the normal pace of oscillation.

  18. Prediction of mixture toxicity from the hormesis of a single chemical: A case study of combinations of antibiotics and quorum-sensing inhibitors with gram-negative bacteria.

    Science.gov (United States)

    Wang, Ting; Wang, Dali; Lin, Zhifen; An, Qingqing; Yin, Chunsheng; Huang, Qinghui

    2016-05-01

    The 50% effect level of a single chemical in the real environment is almost impossible to determine at the low exposure concentration, and the prediction of the concentration of a mixture at the 50% effect level from the concentration of a single chemical at the low effect level is even more difficult. The current literature does not address this problem. Thus, to determine solutions for this question, single/mixture chronic toxicities of sulfonamides (SAs) and quorum-sensing inhibitors (QSIs) were determined using Gram-negative bacteria (Vibrio fischeri and E. coli.) and Gram-positive bacteria (B. subtilis) as the target organisms. The results showed that the joint effects of SAs and QSIs were primarily antagonistic responses. In addition, the toxicity mechanisms of mixtures of SAs and QSIs were investigated further, and the results revealed that the chronic joint effects were primarily an antagonistic response due to the QSI competing against acyl-homoserine lactones (AHL) for luxR in V. fischeri and SdiA in E. coli generated by the SAs, leading to negative effects exerted by the QSI-luxR or QSI-SdiA complexes on luxI in V. fischeri or FtsZ in E. coli. This phenomenon eventually weakened the stimulatory effect caused by the SAs. Based on the mixture toxicity mechanism, the relationship between the mixture toxicity and the simulation effect was formulated.

  19. Acoustic emissions in granular structures under gravitational destabilization

    Science.gov (United States)

    Thirot, J.-L.; Le Gonidec, Y.; Kergosien, B.

    2012-05-01

    In this work, we perform experiments in an acoustic tank to record acoustic emissions (AEs) occurring when a granular medium is submitted to a gravitational destabilization. The granular medium is composed of monodisperse glass beads filling a box which can be inclined from α=0° up to the avalanche threshold angle α0=28°. To respect quasi-static conditions, the angle increases by steps less than 3°/mn. An omnidirectional hydrophone records the continuous acoustic field in the bead structure until the avalanche occurs. We compare the results for different experimental configurations, in particular for dry and water saturated granular media, but also for different bead diameters (d=8, 3 and 0.3 mm) in order to span the viscosity range of the granular structure. We show that the AE signatures strongly depend on the viscosity parameter, which can be related to the Stokes number and the fluid/solid density ratio. The transition from a viscous to an inertial dynamic of the granular structure is discussed, based on these experimental results.

  20. Destabilization of Surfactant-Dispersed Carbon Nanotubes by Anions

    Science.gov (United States)

    Hirano, Atsushi; Gao, Weilu; He, Xiaowei; Kono, Junichiro

    2017-01-01

    The colloidal stability of surfactant-dispersed single-wall carbon nanotubes (SWCNTs) is determined by microscopic physicochemical processes, such as association, partitioning, and adsorption propensities. These processes can be controlled by the addition of solutes. While the effects of cations on the colloidal stability of SWCNTs are relatively well understood, little is known about the effects of anions. In this study, we examined the effects of anions on the stability of SWCNTs dispersed by sodium dodecyl sulfate (SDS) using sodium salts, such as NaCl and NaSCN. We observed that the intensity of the radial breathing mode Raman peaks rapidly decreased as the salts were added, even at concentrations less than 25 mM, indicating the association of SWCNTs. The effect was stronger with NaSCN than NaCl. We propose that the association of SWCNTs was caused by thermodynamic destabilization of SDS assemblies on SWCNT surfaces by these salts, which was confirmed through SWCNT separation experiments using aqueous two-phase extraction and gel chromatography. These results demonstrate that neutral salts can be used to control the colloidal stability of surfactant-dispersed SWCNTs.

  1. Microfluidic destabilization of viscous stratifications: Interfacial waves and droplets

    Science.gov (United States)

    Hu, Xiaoyi; Cubaud, Thomas

    2016-11-01

    Microfluidic two-fluid flows with large differences in viscosity are experimentally investigated to examine the role of fluid properties on hydrodynamic destabilization processes at the small scale. Two- and three-layer flow configurations are systematically studied in straight square microchannels using miscible and immiscible fluid pairs. We focus our attention on symmetric three-layer stratifications with a fast central stream made of low-viscosity fluid and a slow sheath flow composed of high-viscosity fluid. We quantify the influence of the capillary and the Reynolds numbers on the formation and evolution of droplets and wavy stratifications. Several functional relationships are developed for the morphology and dynamics of droplets and interfacial waves including size, celerity and frequency. In the wavy stratification regime, the formation and entrainment of thin viscous ligaments from wave crests display a rich variety of dynamics either in the presence or in the absence of interfacial tension between liquids. This work is supported by NSF (CBET-1150389).

  2. Dlic1 deficiency impairs ciliogenesis of photoreceptors by destabilizing dynein

    Institute of Scientific and Technical Information of China (English)

    Shanshan Kong; Xinrong Du; Chao Peng; Yiming Wu; Huirong Li; Xi Jin; Ling Hou

    2013-01-01

    Cytoplasmic dynein 1 is fundamentally important for transporting a variety of essential cargoes along microtubules within eukaryotic cells.However,in mammals,few mutants are available for studying the effects of defects in dynein-controlled processes in the context of the whole organism.Here,we deleted mouse Dlic1 gene encoding DLIC1,a subunit of the dynein complex.Dlic1-/-mice are viable,but display severe photoreceptor degeneration.Ablation of Dlic1 results in ectopic accumulation of outer segment (OS) proteins,and impairs OS growth and ciliogenesis of photoreceptors by interfering with Rabll-vesicle trafficking and blocking efficient OS protein transport from Golgi to the basal body.Our studies show that Dlic1 deficiency partially blocks vesicle export from endoplasmic reticulum (ER),but seems not to affect vesicle transport from the ER to Golgi.Further mechanistic study reveals that lack of Dlic1 destabilizes dynein subunits and alters the normal subcellular distribution of dynein in photoreceptors,probably due to the impaired transport function of dynein.Our results demonstrate that Dlic1 plays important roles in ciliogenesis and protein transport to the OS,and is required for photoreceptor development and survival.The Dlic1-/-mice also provide a new mouse model to study human retinal degeneration.

  3. Exploring the chemical space around 8-mercaptoguanine as a route to new inhibitors of the folate biosynthesis enzyme HPPK.

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    Sandeep Chhabra

    Full Text Available As the second essential enzyme of the folate biosynthetic pathway, the potential antimicrobial target, HPPK (6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase, catalyzes the Mg(2+-dependant transfer of pyrophosphate from the cofactor (ATP to the substrate, 6-hydroxymethyl-7,8-dihydropterin. Recently, we showed that 8-mercaptoguanine (8-MG bound at the substrate site (KD ∼13 µM, inhibited the S. aureus enzyme (SaHPPK (IC50 ∼ 41 µM, and determined the structure of the SaHPPK/8-MG complex. Here we present the synthesis of a series of guanine derivatives, together with their HPPK binding affinities, as determined by SPR and ITC analysis. The binding mode of the most potent was investigated using 2D NMR spectroscopy and X-ray crystallography. The results indicate, firstly, that the SH group of 8-MG makes a significant contribution to the free energy of binding. Secondly, direct N(9 substitution, or tautomerization arising from N(7 substitution in some cases, leads to a dramatic reduction in affinity due to loss of a critical N(9-H···Val46 hydrogen bond, combined with the limited space available around the N(9 position. The water-filled pocket under the N(7 position is significantly more tolerant of substitution, with a hydroxyl ethyl 8-MG derivative attached to N(7 (compound 21a exhibiting an affinity for the apo enzyme comparable to the parent compound (KD ∼ 12 µM. In contrast to 8-MG, however, 21a displays competitive binding with the ATP cofactor, as judged by NMR and SPR analysis. The 1.85 Å X-ray structure of the SaHPPK/21a complex confirms that extension from the N(7 position towards the Mg(2+-binding site, which affords the only tractable route out from the pterin-binding pocket. Promising strategies for the creation of more potent binders might therefore include the introduction of groups capable of interacting with the Mg(2+ centres or Mg(2+-binding residues, as well as the development of bitopic inhibitors featuring 8-MG

  4. Protein Synthesis Inhibitors Did Not Interfere with Long-Term Depression Induced either Electrically in Juvenile Rats or Chemically in Middle-Aged Rats.

    Science.gov (United States)

    Abbas, Abdul-Karim

    2016-01-01

    In testing the hypothesis that long-term potentiation (LTP) maintenance depends on triggered protein synthesis, we found no effect of protein synthesis inhibitors (PSIs) on LTP stabilization. Similarly, some studies reported a lack of effect of PSIs on long-term depression (LTD); the lack of effect on LTD has been suggested to be resulting from the short time recordings. If this proposal were true, LTD might exhibit sensitivity to PSIs when the recording intervals were enough long. We firstly induced LTD by a standard protocol involving low frequency stimulation, which is suitable for eliciting NMDAR-LTD in CA1 area of hippocampal slices obtained from juvenile Sprague-Dawley rats. This LTD was persistent for intervals in range of 8-10 h. Treating slices with anisomycin, however, did not interfere with the magnitude and persistence of this form of LTD. The failure of anisomycin to block synaptic-LTD might be relied on the age of animal, the type of protein synthesis inhibitors and/or the inducing protocol. To verify whether those variables altogether were determinant, NMDA or DHPG was used to chemically elicit LTD recorded up to 10 h on hippocampal slices obtained from middle-aged rats. In either form of LTD, cycloheximide did not interfere with LTD stabilization. Furthermore, DHPG application did show an increase in the global protein synthesis as assayed by radiolabeled methodology indicating that though triggered protein synthesis can occur but not necessarily required for LTD expression. The findings confirm that stabilized LTD in either juvenile, or middle-aged rats can be independent of triggered protein synthesis. Although the processes responsible for the independence of LTD stabilization on the triggered protein synthesis are not yet defined, these findings raise the possibility that de novo protein synthesis is not universally necessary.

  5. Influences of Chemical Fertilizers and a Nitrification Inhibitor on Greenhouse Gas Fluxes in a Corn (Zea mays L.) Field in Indonesia.

    Science.gov (United States)

    Jumadi, Oslan; Hala, Yusminah; Muis, Abd; Ali, Alimuddin; Palennari, Muhiddin; Yagi, Kazuyuki; Inubushi, Kazuyuki

    2008-01-01

    The influences of chemical fertilizers and a nitrification inhibitor on greenhouse gas fluxes (N(2)O and CH(4)) in a corn field in Indonesia were investigated using a closed chamber. Plots received 45+45 kg-N ha(-1) of nitrogen fertilizer by split applications of urea, a single application of controlled-release fertilizer (CRF-LP30) or urea+dicyandiamide (DCD; a nitrification inhibitor), and no nitrogen application (control). Cumulative amounts of N(2)O emitted from the field were 1.87, 1.70, 1.06, and 0.42 kg N(2)O-N ha(-1) season(-1) for the urea, CRF-LP30, urea+DCD, and control plots, respectively. The application of urea+DCD reduced the emission of N(2)O by 55.8% compared with urea. On the other hand, the soil acted as a sink for CH(4) in the CRL-LP30, control, and urea+DCD plots with value of -0.09, -0.06 and -0.06 kg CH(4)-C ha(-1) season(-1), respectively. When the viability of AOB (ammonia-oxidizing bacteria) and NOB (nitrite-oxidizing bacteria) were monitored, AOB numbers were correlated with the N(2)O emission. These results suggest that 1) there is a potential for reducing emissions of N(2)O by applying DCD, and 2) corn fields treated with CRF or urea+DCD can act as a sink for CH(4) in a tropical humid climate.

  6. High throughput chemical library screening identifies a novel p110-δ inhibitor that potentiates the anti-myeloma effect of bortezomib.

    Science.gov (United States)

    Malek, Ehsan; Driscoll, James J

    2016-06-21

    Multiple myeloma (MM) remains an incurable plasma cell malignancy and drug resistance persists as the major cause of treatment failure leading to fatal outcomes. The phosphatidyl-inositol-3-kinase (PI3K) pathway is constitutively hyperactivated in MM to promote disease progression and drug resistance. While inhibiting PI3K induces apoptosis in MM and is predicted to increase tumor susceptibility to anticancer therapy, early-generation pan-PI3K inhibitors display poor clinical efficacy as well as intolerable side effects. Here, we found that PI3K activity is significantly upregulated in MM cell lines and patient tumor cells resistant to bortezomib and that the majority of PI3K activity in MM cells is dependent upon the p110-δ isoform. Genetic or pharmacologic inhibition of p110-δ substantially reduced myeloma viability and enhanced cellular sensitivity to bortezomib. Chemical library screens then identified a novel compound, DT97, that potently inhibited p110-δ kinase activity and induced apoptosis in MM cells. DT97 was evaluated in the NCI-60 panel of human cancer cell types and anticancer activity was greatest against MM, leukemia and lymphoma cells. Co-treatment with DT97 and bortezomib synergistically induced apoptosis in MM patient cells and overcame bortezomib-resistance. Although bone marrow stromal cells (BMSCs) promote MM growth, the pro-survival effects of BMSCs were significantly reduced by DT97 treatment. Co-treatment with bortezomib and DT97 reduced the growth of myeloma xenotransplants in murine models and prolonged host survival. Taken together, the results provide the basis for further clinical evaluation of p110-δ inhibitors, as monotherapy or in synergistic combinations, for the benefit of MM patients.

  7. Cognitive Fatigue Destabilizes Economic Decision Making Preferences and Strategies.

    Directory of Open Access Journals (Sweden)

    O'Dhaniel A Mullette-Gillman

    Full Text Available It is common for individuals to engage in taxing cognitive activity for prolonged periods of time, resulting in cognitive fatigue that has the potential to produce significant effects in behaviour and decision making. We sought to examine whether cognitive fatigue modulates economic decision making.We employed a between-subject manipulation design, inducing fatigue through 60 to 90 minutes of taxing cognitive engagement against a control group that watched relaxing videos for a matched period of time. Both before and after the manipulation, participants engaged in two economic decision making tasks (one for gains and one for losses. The analyses focused on two areas of economic decision making--preferences and choice strategies. Uncertainty preferences (risk and ambiguity were quantified as premium values, defined as the degree and direction in which participants alter the valuation of the gamble in comparison to the certain option. The strategies that each participant engaged in were quantified through a choice strategy metric, which contrasts the degree to which choice behaviour relies upon available satisficing or maximizing information. We separately examined these metrics for alterations within both the gains and losses domains, through the two choice tasks.The fatigue manipulation resulted in significantly greater levels of reported subjective fatigue, with correspondingly higher levels of reported effort during the cognitively taxing activity. Cognitive fatigue did not alter uncertainty preferences (risk or ambiguity or informational strategies, in either the gains or losses domains. Rather, cognitive fatigue resulted in greater test-retest variability across most of our economic measures. These results indicate that cognitive fatigue destabilizes economic decision making, resulting in inconsistent preferences and informational strategies that may significantly reduce decision quality.

  8. Mode competition and destabilization of microfluidic channel flows by the Coriolis force

    Science.gov (United States)

    Sengupta, Saunak; Saha, Sandeep; Chakraborty, Suman

    2016-11-01

    Understanding flow stability in inertial microfluidics is very important due to its increased application in medical and chemical engineering. On a steady rotating platform centrifugal actuation drives fluid flow but Coriolis force can destabilize the flow and enhance mixing in a short span. We investigate the role of Coriolis force in micro-mixing and the structure of the roll-cells formed in rotating channel flow using linear stability theory. We conduct a parametric study at different rotation numbers, Reynolds number, axial and spanwise wavenumbers. Our results reveal existence of multiple competing unstable modes (Types I to IV) due to Coriolis force: Types I and II have been reported in literature and are responsible for the formation of evenly-spaced roll-cells. We find new instabilities (Types III and IV) which contribute to the formation of twisted roll cells. The existence of the instabilities is clearly demarcated on a regime map to assist future experiments to identify them. The kinetic energy budget has been analyzed to gain insight into the mechanism of energy transfer by Coriolis force from the mean flow to the perturbations. We make a qualitative comparison of roll-cells predicted by linear stability with previously reported experiments.

  9. Modeling chemical interaction profiles: II. Molecular docking, spectral data-activity relationship, and structure-activity relationship models for potent and weak inhibitors of cytochrome P450 CYP3A4 isozyme.

    Science.gov (United States)

    Tie, Yunfeng; McPhail, Brooks; Hong, Huixiao; Pearce, Bruce A; Schnackenberg, Laura K; Ge, Weigong; Buzatu, Dan A; Wilkes, Jon G; Fuscoe, James C; Tong, Weida; Fowler, Bruce A; Beger, Richard D; Demchuk, Eugene

    2012-03-15

    Polypharmacy increasingly has become a topic of public health concern, particularly as the U.S. population ages. Drug labels often contain insufficient information to enable the clinician to safely use multiple drugs. Because many of the drugs are bio-transformed by cytochrome P450 (CYP) enzymes, inhibition of CYP activity has long been associated with potentially adverse health effects. In an attempt to reduce the uncertainty pertaining to CYP-mediated drug-drug/chemical interactions, an interagency collaborative group developed a consensus approach to prioritizing information concerning CYP inhibition. The consensus involved computational molecular docking, spectral data-activity relationship (SDAR), and structure-activity relationship (SAR) models that addressed the clinical potency of CYP inhibition. The models were built upon chemicals that were categorized as either potent or weak inhibitors of the CYP3A4 isozyme. The categorization was carried out using information from clinical trials because currently available in vitro high-throughput screening data were not fully representative of the in vivo potency of inhibition. During categorization it was found that compounds, which break the Lipinski rule of five by molecular weight, were about twice more likely to be inhibitors of CYP3A4 compared to those, which obey the rule. Similarly, among inhibitors that break the rule, potent inhibitors were 2-3 times more frequent. The molecular docking classification relied on logistic regression, by which the docking scores from different docking algorithms, CYP3A4 three-dimensional structures, and binding sites on them were combined in a unified probabilistic model. The SDAR models employed a multiple linear regression approach applied to binned 1D ¹³C-NMR and 1D ¹⁵N-NMR spectral descriptors. Structure-based and physical-chemical descriptors were used as the basis for developing SAR models by the decision forest method. Thirty-three potent inhibitors and 88 weak

  10. Modeling Chemical Interaction Profiles: II. Molecular Docking, Spectral Data-Activity Relationship, and Structure-Activity Relationship Models for Potent and Weak Inhibitors of Cytochrome P450 CYP3A4 Isozyme

    Directory of Open Access Journals (Sweden)

    Eugene Demchuk

    2012-03-01

    Full Text Available Polypharmacy increasingly has become a topic of public health concern, particularly as the U.S. population ages. Drug labels often contain insufficient information to enable the clinician to safely use multiple drugs. Because many of the drugs are bio-transformed by cytochrome P450 (CYP enzymes, inhibition of CYP activity has long been associated with potentially adverse health effects. In an attempt to reduce the uncertainty pertaining to CYP-mediated drug-drug/chemical interactions, an interagency collaborative group developed a consensus approach to prioritizing information concerning CYP inhibition. The consensus involved computational molecular docking, spectral data-activity relationship (SDAR, and structure-activity relationship (SAR models that addressed the clinical potency of CYP inhibition. The models were built upon chemicals that were categorized as either potent or weak inhibitors of the CYP3A4 isozyme. The categorization was carried out using information from clinical trials because currently available in vitro high-throughput screening data were not fully representative of the in vivo potency of inhibition. During categorization it was found that compounds, which break the Lipinski rule of five by molecular weight, were about twice more likely to be inhibitors of CYP3A4 compared to those, which obey the rule. Similarly, among inhibitors that break the rule, potent inhibitors were 2–3 times more frequent. The molecular docking classification relied on logistic regression, by which the docking scores from different docking algorithms, CYP3A4 three-dimensional structures, and binding sites on them were combined in a unified probabilistic model. The SDAR models employed a multiple linear regression approach applied to binned 1D 13C-NMR and 1D 15N-NMR spectral descriptors. Structure-based and physical-chemical descriptors were used as the basis for developing SAR models by the decision forest method. Thirty-three potent inhibitors

  11. Eicosanoid release is increased by membrane destabilization and CFTR inhibition in Calu-3 cells.

    Science.gov (United States)

    Borot, Florence; Vieu, Diane-Lore; Faure, Grazyna; Fritsch, Janine; Colas, Julien; Moriceau, Sandra; Baudouin-Legros, Maryvonne; Brouillard, Franck; Ayala-Sanmartin, Jesus; Touqui, Lhousseine; Chanson, Marc; Edelman, Aleksander; Ollero, Mario

    2009-10-22

    The antiinflammatory protein annexin-1 (ANXA1) and the adaptor S100A10 (p11), inhibit cytosolic phospholipase A2 (cPLA2alpha) by direct interaction. Since the latter is responsible for the cleavage of arachidonic acid at membrane phospholipids, all three proteins modulate eicosanoid production. We have previously shown the association of ANXA1 expression with that of CFTR, the multifactorial protein mutated in cystic fibrosis. This could in part account for the abnormal inflammatory status characteristic of this disease. We postulated that CFTR participates in the regulation of eicosanoid release by direct interaction with a complex containing ANXA1, p11 and cPLA2alpha. We first analyzed by plasmon surface resonance the in vitro binding of CFTR to the three proteins. A significant interaction between p11 and the NBD1 domain of CFTR was found. We observed in Calu-3 cells a rapid and partial redistribution of all four proteins in detergent resistant membranes (DRM) induced by TNF-alpha. This was concomitant with increased IL-8 synthesis and cPLA2alpha activation, ultimately resulting in eicosanoid (PGE2 and LTB4) overproduction. DRM destabilizing agent methyl-beta-cyclodextrin induced further cPLA2alpha activation and eicosanoid release, but inhibited IL-8 synthesis. We tested in parallel the effect of short exposure of cells to CFTR inhibitors Inh172 and Gly-101. Both inhibitors induced a rapid increase in eicosanoid production. Longer exposure to Inh172 did not increase further eicosanoid release, but inhibited TNF-alpha-induced relocalization to DRM. These results show that (i) CFTR may form a complex with cPLA2alpha and ANXA1 via interaction with p11, (ii) CFTR inhibition and DRM disruption induce eicosanoid synthesis, and (iii) suggest that the putative cPLA2/ANXA1/p11/CFTR complex may participate in the modulation of the TNF-alpha-induced production of eicosanoids, pointing to the importance of membrane composition and CFTR function in the regulation of

  12. Eicosanoid release is increased by membrane destabilization and CFTR inhibition in Calu-3 cells.

    Directory of Open Access Journals (Sweden)

    Florence Borot

    Full Text Available The antiinflammatory protein annexin-1 (ANXA1 and the adaptor S100A10 (p11, inhibit cytosolic phospholipase A2 (cPLA2alpha by direct interaction. Since the latter is responsible for the cleavage of arachidonic acid at membrane phospholipids, all three proteins modulate eicosanoid production. We have previously shown the association of ANXA1 expression with that of CFTR, the multifactorial protein mutated in cystic fibrosis. This could in part account for the abnormal inflammatory status characteristic of this disease. We postulated that CFTR participates in the regulation of eicosanoid release by direct interaction with a complex containing ANXA1, p11 and cPLA2alpha. We first analyzed by plasmon surface resonance the in vitro binding of CFTR to the three proteins. A significant interaction between p11 and the NBD1 domain of CFTR was found. We observed in Calu-3 cells a rapid and partial redistribution of all four proteins in detergent resistant membranes (DRM induced by TNF-alpha. This was concomitant with increased IL-8 synthesis and cPLA2alpha activation, ultimately resulting in eicosanoid (PGE2 and LTB4 overproduction. DRM destabilizing agent methyl-beta-cyclodextrin induced further cPLA2alpha activation and eicosanoid release, but inhibited IL-8 synthesis. We tested in parallel the effect of short exposure of cells to CFTR inhibitors Inh172 and Gly-101. Both inhibitors induced a rapid increase in eicosanoid production. Longer exposure to Inh172 did not increase further eicosanoid release, but inhibited TNF-alpha-induced relocalization to DRM. These results show that (i CFTR may form a complex with cPLA2alpha and ANXA1 via interaction with p11, (ii CFTR inhibition and DRM disruption induce eicosanoid synthesis, and (iii suggest that the putative cPLA2/ANXA1/p11/CFTR complex may participate in the modulation of the TNF-alpha-induced production of eicosanoids, pointing to the importance of membrane composition and CFTR function in the

  13. Mechanisms governing the reactivation-dependent destabilization of memories and their role in extinction

    OpenAIRE

    Charlotte Rachael Flavell; Elliot eLambert; Winters, Boyer D.; Bredy, Timothy W.

    2013-01-01

    The extinction of learned associations has traditionally been considered to involve new learning, which competes with the original memory for control over behaviour. However, a recent resurgence of interest in reactivation-dependent amnesia has revealed that the retrieval of fear-related memory (with what is essentially a brief extinction session) can result in it’s destabilization. This review discusses some of the cellular and molecular mechanisms that are involved in the destabilization of...

  14. LKB1 destabilizes microtubules in myoblasts and contributes to myoblast differentiation.

    Directory of Open Access Journals (Sweden)

    Isma Mian

    Full Text Available BACKGROUND: Skeletal muscle myoblast differentiation and fusion into multinucleate myotubes is associated with dramatic cytoskeletal changes. We find that microtubules in differentiated myotubes are highly stabilized, but premature microtubule stabilization blocks differentiation. Factors responsible for microtubule destabilization in myoblasts have not been identified. FINDINGS: We find that a transient decrease in microtubule stabilization early during myoblast differentiation precedes the ultimate microtubule stabilization seen in differentiated myotubes. We report a role for the serine-threonine kinase LKB1 in both microtubule destabilization and myoblast differentiation. LKB1 overexpression reduced microtubule elongation in a Nocodazole washout assay, and LKB1 RNAi increased it, showing LKB1 destabilizes microtubule assembly in myoblasts. LKB1 levels and activity increased during myoblast differentiation, along with activation of the known LKB1 substrates AMP-activated protein kinase (AMPK and microtubule affinity regulating kinases (MARKs. LKB1 overexpression accelerated differentiation, whereas RNAi impaired it. CONCLUSIONS: Reduced microtubule stability precedes myoblast differentiation and the associated ultimate microtubule stabilization seen in myotubes. LKB1 plays a positive role in microtubule destabilization in myoblasts and in myoblast differentiation. This work suggests a model by which LKB1-induced microtubule destabilization facilitates the cytoskeletal changes required for differentiation. Transient destabilization of microtubules might be a useful strategy for enhancing and/or synchronizing myoblast differentiation.

  15. Destabilization of PDK1 by Hsp90 inactivation suppresses hepatitis C virus replication through inhibition of PRK2-mediated viral RNA polymerase phosphorylation.

    Science.gov (United States)

    Kim, Mi-Gyeong; Moon, Jae-Su; Kim, Eun-Jung; Lee, Seung-Hoon; Oh, Jong-Won

    2012-04-27

    Heat shock protein 90 (Hsp90), which chaperones multiple client proteins, has been shown to be implicated in HCV replication. Pharmacological inhibitors of Hsp90 display an anti-HCV activity. However, little is known about the mechanisms of regulation of HCV replication by Hsp90. Here, we show that Hsp90 inhibition by 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG) destabilizes phosphoinositide-dependent kinase-1 (PDK1), an upstream kinase of the protein kinase C-related kinase 2 (PRK2) responsible for phosphorylation of HCV RNA polymerase, through the proteosome pathway. Destabilization of PDK1 led to inhibition of phosphorylation of the viral RNA polymerase through a decrease in the abundance of active form PRK2 level. Consequently, Hsp90 inhibition resulted in suppression of HCV replication both in human hepatoma Huh7 cells harboring an HCV subgenomic replicon and in HCV-infected cells. 17-DMAG treatment did not interfere with HCV internal ribosome entry site-mediated translation and the cell cycle in Huh7 cells. Co-treatment of 17-DMAG with interferon-α or HA1077, an inhibitor of PRK2, enhanced the anti-HCV activity of 17-DMAG. Taken together, these findings suggest that Hsp90 plays a critical role in the regulation of HCV RNA polymerase phosphorylation via the PDK1-PRK2 signaling pathway.

  16. Trypsin inhibitors from the garden four o'clock (Mirabilis jalapa) and spinach (Spinacia oleracea) seeds: isolation, characterization and chemical synthesis.

    Science.gov (United States)

    Kowalska, Jolanta; Pszczoła, Katarzyna; Wilimowska-Pelc, Anna; Lorenc-Kubis, Irena; Zuziak, Ewa; Ługowski, Mateusz; Łegowska, Anna; Kwiatkowska, Anna; Sleszyńska, Małgorzata; Lesner, Adam; Walewska, Aleksandra; Zabłotna, Ewa; Rolka, Krzysztof; Wilusz, Tadeusz

    2007-06-01

    Five serine proteinase inhibitors (Mirabilis jalapa trypsin inhibitors, MJTI I and II and Spinacia oleracea trypsin inhibitors, SOTI I, II, and III) from the garden four-o'clock (M. jalapa) and spinach (S. oleracea) seeds were isolated. The purification procedures included affinity chromatography on immobilized methylchymotrypsin in the presence of 5M NaCl, ion exchange chromatography and/or preparative electrophoresis, and finally RP-HPLC on a C-18 column. The inhibitors, crosslinked by three disulfide bridges, are built of 35 to 37 amino-acid residues. Their primary structures differ from those of known trypsin inhibitors, but showed significant similarity to the antimicrobial peptides isolated from the seeds of M. jalapa (MJ-AMP1, MJ-AMP2), Mesembryanthemum crystallinum (AMP1), and Phytolacca americana (AMP-2 and PAFP-S) and from the hemolymph of Acrocinus longimanus (Alo-1, 2 and 3). The association equilibrium constants (K(a)) with bovine beta-trypsin for the inhibitors from M. jalapa (MJTI I and II) and S. oleracea (SOTI I-III) were found to be about 10(7)M(-1). Fully active MJTI I and SOTI I were obtained by solid-phase peptide synthesis. The disulfide bridge pattern in both inhibitors (Cys1-Cys4, Cys2-Cys5 and Cys3-Cys6) was established after their digestion with thermolysin and proteinase K followed by the MALDI-TOF analysis.

  17. Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

    Directory of Open Access Journals (Sweden)

    S. Gupta

    2016-12-01

    Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

  18. Pattern destabilization and emotional processing in cognitive therapy for personality disorders

    Directory of Open Access Journals (Sweden)

    Adele M. Hayes

    2015-02-01

    Full Text Available Clinical trials of treatments for personality disorders can provide a medium for studying the process of therapeutic change with particularly entrenched and self-perpetuating systems and might reveal important principles of system transition. We examined the extent to which maladaptive personality patterns were destabilized in a trial of cognitive therapy personality disorders (CT-PD and how destabilization was associated with emotional processing and treatment outcomes. Dynamic systems theory was used as a theoretical framework for studying change. Method: Participants were 27 patients diagnosed with Avoidant or Obsessive Compulsive Personality Disorder, who completed an open trial of CT-PD. Raters coded treatment sessions using a coding system that operationalizes emotional processing, as well as cognitive, affective, behavioral, and somatic components of pathological (negative and more adaptive (positive patterns of functioning. Pattern destabilization (dispersion scores during the early phase of treatment (phase 1: session 1-10 and the schema-focused phase (phase 2: session 11-34 were calculated using a program called GridWare. Results: More pattern destabilization and emotional processing in the schema-focused phase of CT-PD predicted more improvement in personality disorder symptoms and positive pattern strength at the end of treatment, whereas these variables in phase 1 did not predict outcome. Conclusions: In addition to illustrating a quantitative method for studying destabilization and change of patterns of psychopathology, we present findings that are consistent with recent updates of emotional processing theory and with principles from dynamic systems theory.

  19. Destabilization analysis of overlapping underground chambers induced by blasting vibration with catastrophe theory

    Institute of Scientific and Technical Information of China (English)

    YAN Chang-bin; XU Guo-yuan; ZUO Yu-jun

    2006-01-01

    According to the main characters of overlapping underground chambers, the roof (floor) of two adjacent underground chambers is simplified to the mechanical model that is the beam with build-in ends. And vibration load due to blasting is simplified to harmonic wave. The catastrophic model of double cusp for underground chambers destabilization induced by blasting vibration has been established under the circumstances of considering deadweight of the beam, and the condition of destabilization has been worked out. The critical safety thickness of the roof (floor) of underground chambers has been confirmed according to the destabilization condition. The influence of amplitude and frequency of blasting vibration load on the critical safety thickness has been analyzed, and the quantitative relation between velocity, frequency of blasting vibration and critical safety thickness has been determined. Research results show that the destabilization of underground chambers is not only dependent on the amplitude and frequency of blasting vibration load, but also related to deadweight load and intrinsic attribute. It is accordant to testing results and some related latest research results of blasting seismic effect. With increasing amplitude, the critical safety thickness of underground chambers decreases gradually. And the possibility of underground chambers destabilization increases. When the frequency of blasting vibration is equal to or very close to the frequency of beam, resonance effect will take place in the system. Then the critical safety thickness will turn to zero, underground chambers will be damaged severely, and its loading capacity will lose on the whole.

  20. EMC1-dependent stabilization drives membrane penetration of a partially destabilized non-enveloped virus

    Science.gov (United States)

    Bagchi, Parikshit; Inoue, Takamasa; Tsai, Billy

    2016-01-01

    Destabilization of a non-enveloped virus generates a membrane transport-competent viral particle. Here we probe polyomavirus SV40 endoplasmic reticulum (ER)-to-cytosol membrane transport, a decisive infection step where destabilization initiates this non-enveloped virus for membrane penetration. We find that a member of the ER membrane protein complex (EMC) called EMC1 promotes SV40 ER membrane transport and infection. Surprisingly, EMC1 does so by using its predicted transmembrane residue D961 to bind to and stabilize the membrane-embedded partially destabilized SV40, thereby preventing premature viral disassembly. EMC1-dependent stabilization enables SV40 to engage a cytosolic extraction complex that ejects the virus into the cytosol. Thus EMC1 acts as a molecular chaperone, bracing the destabilized SV40 in a transport-competent state. Our findings reveal the novel principle that coordinated destabilization-stabilization drives membrane transport of a non-enveloped virus. DOI: http://dx.doi.org/10.7554/eLife.21470.001 PMID:28012275

  1. Nitric oxide destabilizes Pias3 and regulates sumoylation.

    Directory of Open Access Journals (Sweden)

    Jing Qu

    Full Text Available Small ubiquitin-related protein modifiers (SUMO modification is an important mechanism for posttranslational regulation of protein function. However, it is largely unknown how the sumoylation pathway is regulated. Here, we report that nitric oxide (NO causes global hyposumoylation in mammalian cells. Both SUMO E2 conjugating enzyme Ubc9 and E3 ligase protein inhibitor of activated STAT3 (Pias3 were targets for S-nitrosation. S-nitrosation did not interfere with the SUMO conjugating activity of Ubc9, but promoted Pias3 degradation by facilitating its interaction with tripartite motif-containing 32 (Trim32, a ubiquitin E3 ligase. On the one hand, NO promoted Trim32-mediated Pias3 ubiquitination. On the other hand, NO enhanced the stimulatory effect of Pias3 on Trim32 autoubiquitination. The residue Cys459 of Pias3 was identified as a target site for S-nitrosation. Mutation of Cys459 abolished the stimulatory effect of NO on the Pias3-Trim32 interaction, indicating a requirement of S-nitrosation at Cys459 for positive regulation of the Pias3-Trim32 interplay. This study reveals a novel crosstalk between S-nitrosation, ubiquitination, and sumoylation, which may be crucial for NO-related physiological and pathological processes.

  2. Electromagnetic waves destabilized by runaway electrons in near-critical electric fields

    CERN Document Server

    Kómár, A; Fülöp, T

    2013-01-01

    Runaway electron distributions are strongly anisotropic in velocity space. This anisotropy is a source of free energy that may destabilize electromagnetic waves through a resonant interaction between the waves and the energetic electrons. In this work we investigate the high-frequency electromagnetic waves that are destabilized by runaway electron beams when the electric field is close to the critical field for runaway acceleration. Using a runaway electron distribution appropriate for the near-critical case we calculate the linear instability growth rate of these waves and conclude that the obliquely propagating whistler waves are most unstable. We show that the frequencies, wave numbers and propagation angles of the most unstable waves depend strongly on the magnetic field. Taking into account collisional and convective damping of the waves, we determine the number density of runaways that is required to destabilize the waves and show its parametric dependences.

  3. Mechanisms governing the reactivation-dependent destabilization of memories and their role in extinction

    Directory of Open Access Journals (Sweden)

    Charlotte Rachael Flavell

    2013-12-01

    Full Text Available The extinction of learned associations has traditionally been considered to involve new learning, which competes with the original memory for control over behaviour. However, a recent resurgence of interest in reactivation-dependent amnesia has revealed that the retrieval of fear-related memory (with what is essentially a brief extinction session can result in it’s destabilization. This review discusses some of the cellular and molecular mechanisms that are involved in the destabilization of a memory following it’s reactivation and/or extinction, and investigates the evidence that extinction may involve both new learning as well as a partial destabilization-induced erasure of the original memory trace.

  4. Recent changes to the Gulf Stream causing widespread gas hydrate destabilization.

    Science.gov (United States)

    Phrampus, Benjamin J; Hornbach, Matthew J

    2012-10-25

    The Gulf Stream is an ocean current that modulates climate in the Northern Hemisphere by transporting warm waters from the Gulf of Mexico into the North Atlantic and Arctic oceans. A changing Gulf Stream has the potential to thaw and convert hundreds of gigatonnes of frozen methane hydrate trapped below the sea floor into methane gas, increasing the risk of slope failure and methane release. How the Gulf Stream changes with time and what effect these changes have on methane hydrate stability is unclear. Here, using seismic data combined with thermal models, we show that recent changes in intermediate-depth ocean temperature associated with the Gulf Stream are rapidly destabilizing methane hydrate along a broad swathe of the North American margin. The area of active hydrate destabilization covers at least 10,000 square kilometres of the United States eastern margin, and occurs in a region prone to kilometre-scale slope failures. Previous hypothetical studies postulated that an increase of five degrees Celsius in intermediate-depth ocean temperatures could release enough methane to explain extreme global warming events like the Palaeocene-Eocene thermal maximum (PETM) and trigger widespread ocean acidification. Our analysis suggests that changes in Gulf Stream flow or temperature within the past 5,000 years or so are warming the western North Atlantic margin by up to eight degrees Celsius and are now triggering the destabilization of 2.5 gigatonnes of methane hydrate (about 0.2 per cent of that required to cause the PETM). This destabilization extends along hundreds of kilometres of the margin and may continue for centuries. It is unlikely that the western North Atlantic margin is the only area experiencing changing ocean currents; our estimate of 2.5 gigatonnes of destabilizing methane hydrate may therefore represent only a fraction of the methane hydrate currently destabilizing globally. The transport from ocean to atmosphere of any methane released--and thus its

  5. Destabilization and recovery of a yeast prion after mild heat shock.

    Science.gov (United States)

    Newnam, Gary P; Birchmore, Jennifer L; Chernoff, Yury O

    2011-05-06

    Yeast prion [PSI(+)] is a self-perpetuating amyloid of the translational termination factor Sup35. Although [PSI(+)] propagation is modulated by heat shock proteins (Hsps), high temperature was previously reported to have little or no effect on [PSI(+)]. Our results show that short-term exposure of exponentially growing yeast culture to mild heat shock, followed by immediate resumption of growth, leads to [PSI(+)] destabilization, sometimes persisting for several cell divisions after heat shock. Prion loss occurring in the first division after heat shock is preferentially detected in a daughter cell, indicating the impairment of prion segregation that results in asymmetric prion distribution between a mother cell and a bud. Longer heat shock or prolonged incubation in the absence of nutrients after heat shock led to [PSI(+)] recovery. Both prion destabilization and recovery during heat shock depend on protein synthesis. Maximal prion destabilization coincides with maximal imbalance between Hsp104 and other Hsps such as Hsp70-Ssa. Deletions of individual SSA genes increase prion destabilization and/or counteract recovery. The dynamics of prion aggregation during destabilization and recovery are consistent with the notion that efficient prion fragmentation and segregation require a proper balance between Hsp104 and other (e.g., Hsp70-Ssa) chaperones. In contrast to heat shock, [PSI(+)] destabilization by osmotic stressors does not always depend on cell proliferation and/or protein synthesis, indicating that different stresses may impact the prion via different mechanisms. Our data demonstrate that heat stress causes asymmetric prion distribution in a cell division and confirm that the effects of Hsps on prions are physiologically relevant.

  6. Destabilization of fast particle stabilized sawteeth in ASDEX Upgrade with electron cyclotron current drive

    DEFF Research Database (Denmark)

    Igochine, V.; Chapman, I.T.; Bobkov, V.;

    2011-01-01

    It is often observed that large sawteeth trigger the neoclassical tearing mode well below the usual threshold for this instability. At the same time, fast particles in the plasma core stabilize sawteeth and provide these large crashes. The paper presents results of first experiments in ASDEX...... Upgrade for destabilization of fast particle stabilized sawteeth with electron cyclotron current drive (ECCD). It is shown that moderate ECCD from a single gyrotron is able to destabilize the fast particle stabilized sawteeth. A reduction in sawtooth period by about 40% was achieved in first experiments...

  7. Thermodynamic Destabilization of Ti-O Solid Solution by H2 and Deoxygenation of Ti Using Mg.

    Science.gov (United States)

    Zhang, Ying; Fang, Zhigang Zak; Sun, Pei; Zhang, Tuoyang; Xia, Yang; Zhou, Chengshang; Huang, Zhe

    2016-06-08

    Reactive metals including Ti, Zr, Hf, and V, among others, have a strong chemical affinity to oxygen, which makes them difficult to produce and costly to use. It is especially challenging to produce pure or metal alloy powders of these elements when extremely low oxygen content is required, because they have high solubility for oxygen, and the solid solution of these metals with oxygen is often more stable thermodynamically than their oxides. We report a novel thermochemical approach to destabilize Ti(O) solid solutions using hydrogen, thus enabling deoxygenation of Ti powder using Mg, which has not been possible before because of the thermodynamic stability of Ti(O) solid solutions relative to MgO. The work on Ti serves as an example for other reactive metals. Both analytical modeling and experimental results show that hydrogen can indeed increase the oxygen potential of Ti-O solid solution alloys; in other words, the stability of Ti-O solid solutions is effectively decreased, thus increasing the thermodynamic driving force for Mg to react with oxygen in Ti. Because hydrogen can be easily removed from Ti by a simple heat treatment, it is used only as a temporary alloying element to destabilize the Ti-O systems. The thermodynamic approach described here is a breakthrough and is applicable to a range of different materials. This work is expected to provide an enabling solution to overcome one of the key scientific and technological hurdles to the additive manufacturing of metals, which is emerging rapidly as the future of the manufacturing industry.

  8. Cryopegs as destabilization factor of intra-permafrost gas hydrates

    Science.gov (United States)

    Chuvilin, Evgeny; Bukhanov, Boris; Istomin, Vladimir

    2016-04-01

    A characteristic feature of permafrost soils in the Arctic is widespread intra-permafrost unfrozen brine lenses - cryopegs. They are often found in permafrost horizons in the north part of Western Siberia, in particular, on the Yamal Peninsula. Cryopegs depths in permafrost zone can be tens and hundreds of meters from the top of frozen strata. The chemical composition of natural cryopegs is close to sea waters, but is characterized by high mineralization. They have a sodium-chloride primary composition with a minor amount of sulphate. Mineralization of cryopegs brine is often hundreds of grams per liter, and the temperature is around -6…-8 °C. The formation of cryopegs in permafrost is associated with processes of long-term freezing of sediments and cryogenic concentration of salts and salt solutions in local areas. The cryopegs' formation can take place in the course of permafrost evolution at the sea transgressions and regressions during freezing of saline sea sediments. Very important feature of cryopegs in permafrost is their transformation in the process of changing temperature and pressure conditions. As a result, the salinity and chemical composition are changed and in addition the cryopegs' location can be changed during their migration. The cryopegs migration violates the thermodynamic conditions of existence intra-permafrost gas hydrate formations, especially the relic gas hydrates deposits, which are situated in the shallow permafrost up to 100 meters depth in a metastable state [1]. The interaction cryopegs with gas hydrates accumulations can cause decomposition of intra-permafrost hydrates. Moreover, the increasing of salt and unfrozen water content in sedimentary rocks sharply reduce the efficiency of gas hydrates self-preservation in frozen soils. It is confirmed by experimental investigations of interaction of frozen gas hydrate bearing sediments with salt solutions [2]. So, horizons with elevated pressure can appear, as a result of gas hydrate

  9. Computational design, chemical synthesis, and biological evaluation of a novel ERK inhibitor (BL-EI001) with apoptosis-inducing mechanisms in breast cancer.

    Science.gov (United States)

    Liu, Bo; Fu, Leilei; Zhang, Cui; Zhang, Lan; Zhang, Yonghui; Ouyang, Liang; He, Gu; Huang, Jian

    2015-03-30

    Extracellular signal-regulated kinase1/2 (ERK1/2) plays a crucial role in the resistance of apoptosis in carcinogenesis; however, its targeted small-molecule inhibitors still remain to be discovered. Thus, in this study, we computationally and experimentally screened a series of small-molecule inhibitors targeting ERK toward different types of human breast cancer cells. Subsequently, we synthesized some candidate ERK inhibitors, identified a novel ERK inhibitor (BL-EI001) with anti-proliferative activities, and analyzed the BL-EI001/ERK complex. Moreover, we found that BL-EI001 induced breast cancer cell apoptosis via mitochondrial pathway but independent on Ras/Raf/MEK pathway. In addition, we carried out proteomics analyses for exploring some possible BL-EI001-induced apoptotic pathways, and further found that BL-EI001-induced apoptosis affected ERK phosphorylation in breast cancer. Further, we found that BL-EI001 bear anti-tumor activities without remarkable toxicities, and also induced mitochondrial apoptosis by targeting ERK in vivo. Taken together, these results demonstrate that in silico design and experimental discovery of a synthesized small-molecule ERK inhibitor (BL-EI001)as a potential novel apoptosis-inducing drug in the treatment of breast cancer.

  10. Thermal Destabilization of Collagen Matrix Hierarchical Structure by Freeze/Thaw.

    Directory of Open Access Journals (Sweden)

    Altug Ozcelikkale

    Full Text Available This study aims to characterize and understand the effects of freezing on collagen structures and functionality. Specifically, thermodynamic destabilization of collagen at molecular- and fibril-levels by combination of low temperatures and freezing were experimentally characterized using modulated differential scanning calorimetry. In order to delineate the effects of sub-zero temperature and water-ice phase change, we hypothesized that the extent of destabilization can be determined based on post-thaw heat induced thermal denaturation of collagen. It is found that thermal denaturation temperature of collagen in hydrogel decreases by 1.4-1.6°C after freeze/thaw while no such decrease is observed in the case of molecular solution. The destabilization is predominantly due to ice formation. Exposure to low temperatures in the absence of ice has only minimal effect. Calorimetry measurements combined with morphological examination of collagen matrices by scanning electron microscopy suggest that freezing results in destabilization of collagen fibrils due to expansion of intrafibrillar space by ice formation. This fibril-level damage can be alleviated by use of cryoprotectant DMSO at concentrations as low as 0.5 M. A theoretical model explaining the change in collagen post-thaw thermal stability by freezing-induced fibril expansion is also proposed.

  11. Methane seeps, methane hydrate destabilization, and the late Neoproterozoic postglacial cap carbonates

    Institute of Scientific and Technical Information of China (English)

    JIANG Ganqing; SHI Xiaoying; ZHANG Shihong

    2006-01-01

    Methane hydrates constitute the largest pool of readily exchangeable carbon at the Earth's sedimentary carapace and may destabilize, in some cases catastrophically, during times of global-scale warming and/or sea level changes. Given the extreme cold during Neoproterozoic ice ages, the aftermath of such events is perhaps amongst the most likely intervals in Earth history to witness a methane hydrate destabilization event. The coincidence of localized but widespread methane seep-like structures and textures, methane-derived isotopic signal,low sulfate concentration, marine barites, and a prominent, short-lived carbon isotope excursion (δ13C≤-5‰) from the post-Marinoan cap carbonates (~635 Ma) provides strong evidence for a methane hydrate destabilization event during the late Neoproterozoic postglacial warming and transgression. Methane release from hydrates could cause a positive feedback to global warming and oxidation of methane could result in ocean anoxia and fluctuation of atmospheric oxygen, providing an environmental force for the early animal evolution in the latest Neoproterozoic. The issues that remain to be clarified for this event include the trigger of methane hydrate destabilization, the time of initial methane release, the predicted ocean anoxia event and its relationship with the biological innovation, additional geochemical signals in response to methane release, and the regional and global synchrony of cap carbonate precipitation. The Doushantuo cap carbonate in South China provides one of the best examples of its age for a better understanding of these issues.

  12. Stabilization and destabilization effects of the electric field on stochastic precipitate pattern formation

    NARCIS (Netherlands)

    Lagzi, István; Izsák, Ferenc

    2004-01-01

    Stabilization and destabilization effects of an applied electric field on the Liesegang pattern formation in low concentration gradient were studied with numerical model simulations. In the absence of an electric field pattern formation exhibits increasingly stochastic behaviour as the initial conce

  13. Molecular dynamics and quantum chemical calculation studies on 4,4-dimethyl-3-thiosemicarbazide as corrosion inhibitor in 2.5 M H{sub 2}SO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Musa, Ahmed Y., E-mail: ahmed.musa@ymail.com [Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor (Malaysia); Kadhum, Abdul Amir H.; Mohamad, Abu Bakar; Takriff, Mohd Sobri [Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor (Malaysia)

    2011-09-15

    Highlights: {yields} This work deals with a study of chemical additives for corrosion inhibition of mild steel in acidic conditions. {yields} The effects of the additive 4,4-dimethyl-3-thiosemicarbazide (DTS) on mild steel were studied by means of electrochemical techniques. {yields} Quantum chemical calculations and molecular dynamic model were performed to characterize the inhibition mechanism. {yields} The calculations provided information that helps in the analysis/interpretation of the experimental work. - Abstract: The inhibition of mild steel corrosion in a 2.5 M H{sub 2}SO{sub 4} solution by 4,4-dimethyl-3-thiosemicarbazide (DTS) was studied at 30 deg. C using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Quantum chemical parameters were calculated for DTS using PM3-SCF method. The molecular dynamic method was performed to simulate the adsorption of the DTS molecules on Fe surface. Results showed that DTS performed excellent as inhibitor for mild steel corrosion in a 2.5 M H{sub 2}SO{sub 4} solution and indicated that the inhibition efficiencies increase with the concentration of inhibitor. Theoretical results indicated that DTS could adsorb on the mild steel surface firmly through heteroatoms.

  14. E-cadherin destabilization accounts for the pathogenicity of missense mutations in hereditary diffuse gastric cancer.

    Directory of Open Access Journals (Sweden)

    Joana Simões-Correia

    Full Text Available E-cadherin is critical for the maintenance of tissue architecture due to its role in cell-cell adhesion. E-cadherin mutations are the genetic cause of Hereditary Diffuse Gastric Cancer (HDGC and missense mutations represent a clinical burden, due to the uncertainty of their pathogenic role. In vitro and in vivo, most mutations lead to loss-of-function, although the causal factor is unknown for the majority. We hypothesized that destabilization could account for the pathogenicity of E-cadherin missense mutations in HDGC, and tested our hypothesis using in silico and in vitro tools. FoldX algorithm was used to calculate the impact of each mutation in E-cadherin native-state stability, and the analysis was complemented with evolutionary conservation, by SIFT. Interestingly, HDGC patients harbouring germline E-cadherin destabilizing mutants present a younger age at diagnosis or death, suggesting that the loss of native-state stability of E-cadherin accounts for the disease phenotype. To elucidate the biological relevance of E-cadherin destabilization in HDGC, we investigated a group of newly identified HDGC-associated mutations (E185V, S232C and L583R, of which L583R is predicted to be destabilizing. We show that this mutation is not functional in vitro, exhibits shorter half-life and is unable to mature, due to premature proteasome-dependent degradation, a phenotype reverted by stabilization with the artificial mutation L583I (structurally tolerated. Herein we report E-cadherin structural models suitable to predict the impact of the majority of cancer-associated missense mutations and we show that E-cadherin destabilization leads to loss-of-function in vitro and increased pathogenicity in vivo.

  15. Molecular mechanisms for the destabilization and restabilization of reactivated spatial memory in the Morris water maze

    Directory of Open Access Journals (Sweden)

    Kim Ryang

    2011-02-01

    Full Text Available Abstract Background Memory retrieval is not a passive process. Recent studies have shown that reactivated memory is destabilized and then restabilized through gene expression-dependent reconsolidation. Molecular studies on the regulation of memory stability after retrieval have focused almost exclusively on fear memory, especially on the restabilization process of the reactivated fear memory. We previously showed that, similarly with fear memories, reactivated spatial memory undergoes reconsolidation in the Morris water maze. However, the underlying molecular mechanisms by which reactivated spatial memory is destabilized and restabilized remain poorly understood. In this study, we investigated the molecular mechanism that regulates the stability of the reactivated spatial memory. Results We first showed that pharmacological inactivation of the N-methyl-D-aspartate glutamate receptor (NMDAR in the hippocampus or genetic inhibition of cAMP-responsible element binding protein (CREB-mediated transcription disrupted reactivated spatial memory. Finally, we showed that pharmacological inhibition of cannabinoid receptor 1 (CB1 and L-type voltage gated calcium channels (LVGCCs in the hippocampus blocked the disruption of the reactivated spatial memory by the inhibition of protein synthesis. Conclusions Our findings indicated that the reactivated spatial memory is destabilized through the activation of CB1 and LVGCCs and then restabilized through the activation of NMDAR- and CREB-mediated transcription. We also suggest that the reactivated spatial memory undergoes destabilization and restabilization in the hippocampus, through similar molecular processes as those for reactivated contextual fear memories, which require CB1 and LVGCCs for destabilization and NMDAR and CREB for restabilization.

  16. The Epidermal Growth Factor Receptor (EGFR) Inhibitor Gefitinib Reduces but Does Not Prevent Tumorigenesis in Chemical and Hormonal Induced Hepatocarcinogenesis Rat Models

    OpenAIRE

    Silvia Ribback; Verena Sailer; Enrico Böhning; Julia Günther; Jaqueline Merz; Frauke Steinmüller; Kirsten Utpatel; Antonio Cigliano; Kristin Peters; Pilo, Maria G.; Matthias Evert; Calvisi, Diego F.; Frank Dombrowski

    2016-01-01

    Activation of the epidermal growth factor receptor (EGFR) signaling pathway promotes the development of hepatocellular adenoma (HCA) and carcinoma (HCC). The selective EGFR inhibitor Gefitinib was found to prevent hepatocarcinogenesis in rat cirrhotic livers. Thus, Gefitinib might reduce progression of pre-neoplastic liver lesions to HCC. In short- and long-term experiments, administration of N-Nitrosomorpholine (NNM) or intrahepatic transplantation of pancreatic islets in diabetic (PTx), thy...

  17. A comparative electrochemical and quantum chemical calculation study of BTAH and BTAOH as copper corrosion inhibitors in near neutral chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Finsgar, Matjaz; Lesar, Antonija; Kokalj, Anton [Jozef Stefan Institute, Department of Physical and Organic Chemistry, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Milosev, Ingrid [Jozef Stefan Institute, Department of Physical and Organic Chemistry, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Valdoltra Orthopaedic Hospital, Jadranska c. 31, SI-6280 Ankaran (Slovenia)], E-mail: ingrid.milosev@ijs.si

    2008-11-30

    The inhibition of copper corrosion in 3% NaCl solution was studied by using a well-known inhibitor, benzotriazole (BTAH), and its not so extensively explored derivative, 1-hydroxybenzotriazole (BTAOH). Electrochemical methods, i.e., linear polarization, Tafel and potentiodynamic curve measurements and electrochemical quartz crystal microbalance (EQCM) measurements were used. Corrosion parameters and inhibition effectiveness were determined. Experimental results showed that benzotriazole is a more effective inhibitor of the corrosion of copper in chloride media than 1-hydroxybenzotriazole. Whereas in the presence of BTAH a protective Cu-BTA layer is formed on the Cu surface, in the presence of BTAOH a thick, poorly protective layer is formed, which readily dissolves in chloride solution. Kinetic parameters were calculated based on EQCM results. Adsorption of BTAOH follows a linear growth law, in contrast to BTAH, whose film growth can be best represented at first by a parabolic, and later by logarithmic, growth law. Different mechanisms of growth imply different mechanisms of inhibition and account for the different inhibition effectiveness. Density functional theory calculations were performed to characterize certain features of the molecular structures, including the electronic parameters related to the inhibition effectiveness of these inhibitors. Introduction of the -OH group into the benzotriazole molecules does not change their electronic parameters significantly neither in gas phase nor in the presence of water solvent. Other parameters, therefore, affect the inhibition effectiveness of these corrosion inhibitors. In particular, superior inhibition effectiveness of BTAH is attributed to interplay of planar molecular structure, physisorption and intermolecular H-bonding, which cooperatively may result in formation of thin and protective film on the surface.

  18. Biocatalysts with enhanced inhibitor tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shihui; Linger, Jeffrey; Franden, Mary Ann; Pienkos, Philip T.; Zhang, Min

    2015-12-08

    Disclosed herein are biocatalysts for the production of biofuels, including microorganisms that contain genetic modifications conferring tolerance to growth and fermentation inhibitors found in many cellulosic feedstocks. Methods of converting cellulose-containing materials to fuels and chemicals, as well as methods of fermenting sugars to fuels and chemicals, using these biocatalysts are also disclosed.

  19. Adsorption and Corrosion Inhibition Studies of Some Selected Dyes as Corrosion Inhibitors for Mild Steel in Acidic Medium: Gravimetric, Electrochemical, Quantum Chemical Studies and Synergistic Effect with Iodide Ions

    Directory of Open Access Journals (Sweden)

    Thabo Peme

    2015-09-01

    Full Text Available The corrosion inhibition properties of some organic dyes, namely Sunset Yellow (SS, Amaranth (AM, Allura Red (AR, Tartrazine (TZ and Fast Green (FG, for mild steel corrosion in 0.5 M HCl solution, were investigated using gravimetric, potentiodynamic polarization techniques and quantum chemical calculations. The results showed that the studied dyes are good corrosion inhibitors with enhanced inhibition efficiencies. The inhibition efficiency of all the studied dyes increases with increase in concentration, and decreases with increase in temperature. The results showed that the inhibition efficiency of the dyes increases in the presence of KI due to synergistic interactions of the dye molecules with iodide (I− ions. Potentiodynamic polarization results revealed that the studied dyes are mixed-type inhibitors both in the absence and presence of KI. The adsorption of the studied dyes on mild steel surface, with and without KI, obeys the Langmuir adsorption isotherm and involves physical adsorption mechanism. Quantum chemical calculations revealed that the most likely sites in the dye molecules for interactions with mild steel are the S, O, and N heteroatoms.

  20. Adsorption and Corrosion Inhibition Studies of Some Selected Dyes as Corrosion Inhibitors for Mild Steel in Acidic Medium: Gravimetric, Electrochemical, Quantum Chemical Studies and Synergistic Effect with Iodide Ions.

    Science.gov (United States)

    Peme, Thabo; Olasunkanmi, Lukman O; Bahadur, Indra; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-09-02

    The corrosion inhibition properties of some organic dyes, namely Sunset Yellow (SS), Amaranth (AM), Allura Red (AR), Tartrazine (TZ) and Fast Green (FG), for mild steel corrosion in 0.5 M HCl solution, were investigated using gravimetric, potentiodynamic polarization techniques and quantum chemical calculations. The results showed that the studied dyes are good corrosion inhibitors with enhanced inhibition efficiencies. The inhibition efficiency of all the studied dyes increases with increase in concentration, and decreases with increase in temperature. The results showed that the inhibition efficiency of the dyes increases in the presence of KI due to synergistic interactions of the dye molecules with iodide (I(-)) ions. Potentiodynamic polarization results revealed that the studied dyes are mixed-type inhibitors both in the absence and presence of KI. The adsorption of the studied dyes on mild steel surface, with and without KI, obeys the Langmuir adsorption isotherm and involves physical adsorption mechanism. Quantum chemical calculations revealed that the most likely sites in the dye molecules for interactions with mild steel are the S, O, and N heteroatoms.

  1. The cystic-fibrosis-associated ΔF508 mutation confers post-transcriptional destabilization on the C. elegans ABC transporter PGP-3

    Directory of Open Access Journals (Sweden)

    Liping He

    2012-11-01

    Membrane proteins make up ∼30% of the proteome. During the early stages of maturation, this class of proteins can experience localized misfolding in distinct cellular compartments, such as the cytoplasm, endoplasmic reticulum (ER lumen and ER membrane. ER quality control (ERQC mechanisms monitor folding and determine whether a membrane protein is appropriately folded or is misfolded and warrants degradation. ERQC plays crucial roles in human diseases, such as cystic fibrosis, in which deletion of a single amino acid (F508 results in the misfolding and degradation of the cystic fibrosis transmembrane conductance regulator (CFTR Cl– channel. We introduced the ΔF508 mutation into Caenorhabditis elegans PGP-3, a 12-transmembrane ABC transporter with 15% identity to CFTR. When expressed in intestinal epithelial cells, PGP-3wt was stable and efficiently trafficked to the apical plasma membrane through a COPII-dependent mechanism. However, PGP-3ΔF508 was post-transcriptionally destabilized, resulting in reduced total and apical membrane protein levels. Genetic or physiological activation of the osmotic stress response pathway, which causes accumulation of the chemical chaperone glycerol, stabilized PGP-3ΔF508. Efficient degradation of PGP-3ΔF508 required the function of several C. elegans ER-associated degradation (ERAD homologs, suggesting that destabilization occurs through an ERAD-type mechanism. Our studies show that the ΔF508 mutation causes post-transcriptional destabilization and degradation of PGP-3 in C. elegans epithelial cells. This model, combined with the power of C. elegans genetics, provides a new opportunity to genetically dissect metazoan ERQC.

  2. Dispersal-induced destabilization of metapopulations and oscillatory Turing patterns in ecological networks

    Science.gov (United States)

    Hata, Shigefumi; Nakao, Hiroya; Mikhailov, Alexander S.

    2014-01-01

    As shown by Alan Turing in 1952, differential diffusion may destabilize uniform distributions of reacting species and lead to emergence of patterns. While stationary Turing patterns are broadly known, the oscillatory instability, leading to traveling waves in continuous media and sometimes called the wave bifurcation, remains less investigated. Here, we extend the original analysis by Turing to networks and apply it to ecological metapopulations with dispersal connections between habitats. Remarkably, the oscillatory Turing instability does not lead to wave patterns in networks, but to spontaneous development of heterogeneous oscillations and possible extinction of species. We find such oscillatory instabilities for all possible food webs with three predator or prey species, under various assumptions about the mobility of individual species and nonlinear interactions between them. Hence, the oscillatory Turing instability should be generic and must play a fundamental role in metapopulation dynamics, providing a common mechanism for dispersal-induced destabilization of ecosystems.

  3. Calcium signaling and mitochondrial destabilization in the triggering of the NLRP3 inflammasome.

    Science.gov (United States)

    Horng, Tiffany

    2014-06-01

    The NLRP3 inflammasome is a cytosolic complex that activates Caspase-1, leading to maturation of interleukin-1β (IL-1β) and IL-18 and induction of proinflammatory cell death in sentinel cells of the innate immune system. Diverse stimuli have been shown to activate the NLRP3 inflammasome during infection and metabolic diseases, implicating the pathway in triggering both adaptive and maladaptive inflammation in various clinically important settings. Here I discuss the emerging model that signals associated with mitochondrial destabilization may critically activate the NLRP3 inflammasome. Together with studies indicating an important role for Ca2+ signaling, these findings suggest that many stimuli engage Ca2+ signaling as an intermediate step to trigger mitochondrial destabilization, generating the mitochondrion-associated ligands that activate the NLRP3 inflammasome.

  4. Chaos in temporarily destabilized regular systems with the slow passage effect

    Energy Technology Data Exchange (ETDEWEB)

    Perc, Matjaz [Department of Physics, Faculty of Education, University of Maribor, Koroska cesta 160, SI-2000 Maribor (Slovenia)] e-mail: matjaz.perc@uni-mb.si; Marhl, Marko [Department of Physics, Faculty of Education, University of Maribor, Koroska cesta 160, SI-2000 Maribor (Slovenia)

    2006-01-01

    We provide evidences for chaotic behaviour in temporarily destabilized regular systems. In particular, we focus on time-continuous systems with the slow passage effect. The extreme sensitivity of the slow passage phase enables the existence of long chaotic transients induced by random pulsatile perturbations, thereby evoking chaotic behaviour in an initially regular system. We confirm the chaotic behaviour of the temporarily destabilized system by calculating the largest Lyapunov exponent. Moreover, we show that the newly obtained unstable periodic orbits can be easily controlled with conventional chaos control techniques, thereby guaranteeing a rich diversity of accessible dynamical states that is usually expected only in intrinsically chaotic systems. Additionally, we discuss the biological importance of presented results.

  5. Destabilization kinetics of polyvinylpyrrolidone-iodine in a field of low frequency impacts

    Science.gov (United States)

    Fadeev, G. N.; Ermolaeva, V. I.; Boldyrev, V. S.; Sinkevich, V. V.

    2016-09-01

    Experimental results on the destabilization kinetics of compounds with chelate structure (polyvinylpyrrolidone-iodine) in the field of the impact of low-frequency vibrations (from 2 to 45 Hz) are presented. The optimum frequencies at which the process rate is greatest are found for different impact modes. Based on the experimental data, conclusions are drawn as to the effect the energy of low-frequency impacts has on the studied clathrate and chelate structures.

  6. Critical thinking of destabilizing interpretations of events and phenomena: the role of economic sciences

    Directory of Open Access Journals (Sweden)

    Тетяна Андріївна Непокупна

    2015-03-01

    Full Text Available This article analyzes the global transformations and their impact on the main society life; the specifics of modern interpretations of events and phenomena, their destabilizing effects on behavior, health and life of humans; the role of economic sciences in the formation of critical thinking as a means of combating ignorance and propaganda, formation of an objective world view that grounded on knowledge

  7. Destabilization and recovery of a yeast prion after mild heat shock

    OpenAIRE

    Newnam, Gary P.; Birchmore, Jennifer L.; Chernoff, Yury O.

    2011-01-01

    Yeast prion [PSI+] is a self-perpetuating amyloid of the translational termination factor Sup35. Although [PSI+] propagation is modulated by heat shock proteins (Hsps), high temperature was previously reported to have little or no effect on [PSI+]. Our results show that short-term exposure of exponentially growing yeast culture to mild heat shock, followed by immediate resumption of growth, leads to [PSI+] destabilization, sometimes persisting for several cell divisions after heat shock. Prio...

  8. Data from Tiered High-Throughput Screening Approach to Identify Thyroperoxidase Inhibitors within the ToxCast Phase I and II Chemical Libraries

    Data.gov (United States)

    U.S. Environmental Protection Agency — High-throughput screening for potential thyroid-disrupting chemicals requires a system of assays to capture multiple molecular-initiating events (MIEs) that converge...

  9. Study of nonlinear behaviors and modal reductions for friction destabilized systems. Application to an elastic layer

    Science.gov (United States)

    Loyer, A.; Sinou, J.-J.; Chiello, O.; Lorang, X.

    2012-02-01

    As noise reduction tends to be part of environmental directives, predicting squeal noise generated by disc brakes is an important industrial issue. It involves both the transient and stationary nonlinear dynamics of self-excited systems with frictional contact. Time simulation of the phenomenon is an attractive option for reducing experiment costs. However, since such computations using full finite element models of industrial disc brake systems is time-consuming, model reduction has to be performed. In this paper, both the transient and stationary nonlinear behaviors of the friction destabilized system and the effect of dynamical reduction on the nonlinear response of a simple friction destabilized system are carried out. The first part provides a description of the general modeling retained for friction destabilized systems. Then, discretization and solving processes for the stability analysis and the temporal evolution are presented. The third part presents an analysis of a sliding elastic layer for different operating conditions, in order to better understand the nonlinear behavior of such systems. Finally, spatial model reduction is performed with different kinds of reduction bases in order to analyze the different effects of modal reductions. This clearly shows the necessity of including static modes in the reduction basis and that nonlinear interactions between unstable modes are very difficult to represent with reduced bases. Finally, the proposed model and the associated studies are intended to be the benchmark cases for future comparison.

  10. Posturographic destabilization in eating disorders in female patients exposed to body image related phobic stimuli.

    Science.gov (United States)

    Forghieri, M; Monzani, D; Mackinnon, A; Ferrari, S; Gherpelli, C; Galeazzi, G M

    2016-08-26

    Human postural control is dependent on the central integration of vestibular, visual and proprioceptive inputs. Psychological states can affect balance control: anxiety, in particular, has been shown to influence balance mediated by visual stimuli. We hypothesized that patients with eating disorders would show postural destabilization when exposed to their image in a mirror and to the image of a fashion model representing their body ideal in comparison to body neutral stimuli. Seventeen females patients attending a day centre for the treatment of eating disorders were administered psychometric measures of body dissatisfaction, anxiety, depression and underwent posturographic measures with their eyes closed, open, watching a neutral stimulus, while exposed to a full length mirror and to an image of a fashion model corresponding to their body image. Results were compared to those obtained by eighteen healthy subjects. Eating disordered patients showed higher levels of body dissatisfaction and higher postural destabilization than controls, but this was limited to the conditions in which they were exposed to their mirror image or a fashion model image. Postural destabilization under these conditions correlated with measures of body dissatisfaction. In eating disordered patients, body related stimuli seem to act as phobic stimuli in the posturographic paradigm used. If confirmed, this has the potential to be developed for diagnostic and therapeutic purposes.

  11. Dynamic destabilization analysis based on AE experiment of deep-seated, steep-inclined and extra-thick coal seam

    Institute of Scientific and Technical Information of China (English)

    Fenhua Ren; Xingping Lai; Meifeng Cai

    2008-01-01

    No. 5 coal seam in Huating Coal Mine is a deep-seated, steep-inclined extra-thick coal seam where excavation disturbance is quite frequent. The maximum and minimum principal stresses differ widely. During mining, dynamical destabilization happens frequently and induce tragedies. Based on the comparison between the acoustic emission (AE) experiment on dynamical destabilization of coal rock and the related in situ testing results, this article provides comprehensive analysis on the regular quantificational AE patterns (energy rate, total events) of coal rock destabilization in complex-variable environment. The comparison parameters include dynamic tension energy rate, deformation resistance to compression, and shear stress.

  12. Nutrient/serum starvation derived TRIP-Br3 down-regulation accelerates apoptosis by destabilizing XIAP

    Science.gov (United States)

    Lee, Soonduck; Jeong, Dongjun; Yang, Young; Kim, Keun-Il; Lim, Jong-Seok; Cheon, Chung-Il; Kim, Changjin; Kang, Young-Sook; Lee, Myeong-Sok

    2015-01-01

    TRIP-Br3 and TRIP-Br1 have shown to have important biological functions. However, the function of TRIP-Br3 in tumorigenesis is not well characterized compared to oncogenic TRIP-Br1. Here, we investigated the function of TRIP-Br3 in tumorigenesis by comparing with that of TRIP-Br1. Under nutrient/serum starvation, TRIP-Br3 expression was down-regulated slightly in cancer cells and significantly in normal cells. Unexpectedly, TRIP-Br1 expression was greatly up-regulated in cancer cells but not in normal cells. Moreover, TRIP-Br3 activated autophagy while TRIP-Br1 inactivated it under serum starvation. In spite of different expression and roles of TRIP-Br3 and TRIP-Br1, both of them alleviate cell death by directly binding to and stabilizing XIAP, a potent apoptosis inhibitor, through blocking its ubiquitination. Taken together, we propose that TRIP-Br3 primarily activates the autophagy and suppresses apoptosis in nutrient sufficient condition. However, the prolonged extreme stressful condition of nutrient starvation causes a dramatic decrease of TRIP-Br3, which in turn induces apoptosis by destabilizing XIAP. Up-regulated TRIP-Br1 in cancer cells compensates this effect and delays apoptosis. This can be explained by the competitive alternative binding of TRIP-Br3 and TRIP-Br1 to the BIR2 domain of XIAP. In an extended study, our immunohistochemical analysis revealed a markedly lower level of TRIP-Br3 protein in human carcinoma tissues compared to normal epithelial tissues, implying the role of TRIP-Br3 as a tumor suppressor rather than onco-protein. PMID:25691055

  13. 铜抛光液中缓蚀剂5-氨基四唑(ATA)的作用机制研究%Investigation on the Mechanisms of Corrosion Inhibitor 5-aminotetrazole Used in the Copper Chemical Mechanical Polishing

    Institute of Scientific and Technical Information of China (English)

    刘宇宏; 董莹; 戴媛静; 雒建斌

    2012-01-01

    The influences of inhibitors ( benzotriazole( BTA)and 5-aminotetrazole( ATA) )in slurry with varying pH values on the chemical mechanical polishing( CMP) of copper were studied by the methods of the static corrosion, contact angle and X-ray photoelectron spectroscopy(XPS) ,and the effective mechanisms of ATA on copper surface were discussed. The results show that BTA and ATA are excellent copper corrosion inhibitors. In the range of pH values 3 - 10, the inhibitors form the passivity films and protect the copper surface from chemical attack, resulting in the decrease of the removal rates of copper and static corrosion rates,especially in the optimum condition of pH =4. ATA has better inhibition effect for copper corrosion than BTA in the range of pH =3 ~5, because ATA molecule can be preferentially adsorbed on copper surface by nitrogen atoms of amidogen and azole to form the protect films, resulting in the inhibition of the oxide formation from hydrogen peroxide and the improvement of the surface quality. In conclusion, ATA is one of the best inhibitors suitable for acid slurry of copper CMP.%采用静态腐蚀实验、接触角测试、XPS等手段,比较在不同pH值下抛光液中缓蚀剂(5-氨基四唑(ATA),苯并三唑(BTA))对铜表面化学机械抛光(CMP)的影响,并探讨ATA在铜表面的作用机制.结果表明,BTA和ATA是优良的铜缓蚀剂,当pH值为3~10时,两者可在铜表面成膜,保护铜表面不受腐蚀,从而降低铜片的静态腐蚀速率和去除率,其中当pH =4时,2种缓蚀剂表现出最佳的缓蚀性能.当pH值为3~5时,ATA的缓蚀性能优于BTA.ATA通过四唑环上的N原子和氨基上的N原子吸附在铜表面,形成保护膜,从而抑制了H2O2对铜表面的腐蚀,改善了表面质量,是一种优良的适用于酸性铜抛光液的缓蚀剂.

  14. Quantum chemical analysis on molecular structures and inhibitive properties of imidazoline inhibitors%咪唑啉缓蚀剂分子结构与缓蚀性能的量子化学分析

    Institute of Scientific and Technical Information of China (English)

    胡松青; 贾晓林; 胡建春; 石鑫; 郭爱玲

    2011-01-01

    采用量子化学密度泛函理论,考察6种十一烷基咪唑啉缓蚀剂的缓蚀性能与分子结构的关系,通过前线轨道分布、Fukui指数、自然电荷分布以及分子中重原子对前线轨道贡献等分析缓蚀剂分子的反应活性位点.结果表明:咪唑啉类缓蚀剂分子与金属界面作用时,主要是咪唑环和亲水支链上的极性基团起作用,分子的活性位点主要分布在咪唑环及亲水取代基上的N、O、S等杂原子处;缓蚀剂的缓蚀效率与分子最高占有轨道能量(EHOMO)、最低空轨道能量(ELUMO)及分子负电荷总数(nTNC)都有较好的相关性;咪唑啉缓蚀剂与金属相互作用时,既能向金属原子的空轨道提供电子形成配位键,又可从金属中接受电子到缓蚀剂分子最低空轨道上形成反馈键,从而形成稳定的吸附.%The relationships between molecular structures of six undecyl imidazoline inhibitors and their inhibitive performance were investigated by using quantum chemical density functional theory (DFT). Via analysis of frontier orbital distribution, Fukui index, natural charge distribution and contribution to frontier orbital of heavy atoms, the reaction active sites of imidazoline molecules were obtained. The results indicate that imidazoline ring and its polar functional group on the hydrophilic chain play a significant role when inhibitors react with metal surface, and the reaction active sites mainly concentrate on the imidazoline ring and atoms of N,O,S located on hydrophilic substituent. The inhibition efficiency is closely related to some quantum chemical parameters of corrosion inhibitors such as the highest occupation orbital energy EHOMO, the lowest empty orbital energy ELUMO and total number of molecular negative charge nTNC. The imidazoline molecules could form coordinate bond and back-donating bond to metal surface when inhibitors react with metal, and stable adsorption could be formed.

  15. The destabilizing effect of external damping: Singular utter boundary for the Pfluger column with vanishing external dissipation

    CERN Document Server

    Tommasini, Mirko; Misseroni, Diego; Bigoni, Davide

    2016-01-01

    Elastic structures loaded by nonconservative positional forces are prone to instabilities induced by dissipation: it is well-known in fact that internal viscous damping destabilizes the marginally stable Ziegler's pendulum and Pfluger column (of which the Beck's column is a special case), two structures loaded by a tangential follower force. The result is the so-called 'destabilization paradox', where the critical force for flutter instability decreases by an order of magnitude when the coefficient of internal damping becomes infinitesimally small. Until now external damping, such as that related to air drag, is believed to provide only a stabilizing effect, as one would intuitively expect. Contrary to this belief, it will be shown that the effect of external damping is qualitatively the same as the effect of internal damping, yielding a pronounced destabilization paradox. Previous results relative to destabilization by external damping of the Ziegler's and Pfluger's elastic structures are corrected in a defi...

  16. DNA-Destabilizing Agents as an Alternative Approach for Targeting DNA: Mechanisms of Action and Cellular Consequences

    Directory of Open Access Journals (Sweden)

    Gaëlle Lenglet

    2010-01-01

    Full Text Available DNA targeting drugs represent a large proportion of the actual anticancer drug pharmacopeia, both in terms of drug brands and prescription volumes. Small DNA-interacting molecules share the ability of certain proteins to change the DNA helix's overall organization and geometrical orientation via tilt, roll, twist, slip, and flip effects. In this ocean of DNA-interacting compounds, most stabilize both DNA strands and very few display helix-destabilizing properties. These types of DNA-destabilizing effect are observed with certain mono- or bis-intercalators and DNA alkylating agents (some of which have been or are being developed as cancer drugs. The formation of locally destabilized DNA portions could interfere with protein/DNA recognition and potentially affect several crucial cellular processes, such as DNA repair, replication, and transcription. The present paper describes the molecular basis of DNA destabilization, the cellular impact on protein recognition, and DNA repair processes and the latter's relationships with antitumour efficacy.

  17. Effect of Processing Conditions on the Crystallization behavior and Destabilization Kinetics of Oil-in-Water Emulsions

    OpenAIRE

    Martini, Silvana; Tippetts, Megan

    2008-01-01

    The objective of this research was to systematically study the effect of processing conditions on the crystallization behavior and destabilization mechanisms of oil-in-water emulsions. The effect of crystallization temperature (T c) and homogenization conditions on both thermal behavior and destabilization mechanisms were analyzed. Results show that the crystallization of lipids present in the emulsions was inhibited when compared with bulk lipids as evidenced by a lower onset and peak temper...

  18. Tiered High-Throughput Screening Approach to Identify Thyroperoxidase Inhibitors within the ToxCast Phase I and II Chemical Libraries

    Science.gov (United States)

    High-throughput screening (HTS) for potential thyroid–disrupting chemicals requires a system of assays to capture multiple molecular-initiating events (MIEs) that converge on perturbed thyroid hormone (TH) homeostasis. Screening for MIEs specific to TH-disrupting pathways is limi...

  19. Carborane-Based Carbonic Anhydrase Inhibitors: Insight into CAII/CAIX Specificity from a High-Resolution Crystal Structure, Modeling, and Quantum Chemical Calculations

    Directory of Open Access Journals (Sweden)

    Pavel Mader

    2014-01-01

    Full Text Available Carborane-based compounds are promising lead structures for development of inhibitors of carbonic anhydrases (CAs. Here, we report structural and computational analysis applicable to structure-based design of carborane compounds with selectivity toward the cancer-specific CAIX isoenzyme. We determined the crystal structure of CAII in complex with 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane at 1.0 Å resolution and used this structure to model the 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane interactions with CAIX. A virtual glycine scan revealed the contributions of individual residues to the energy of binding of 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane to CAII and CAIX, respectively.

  20. Multikinase activity of fibroblast growth factor receptor (FGFR) inhibitors SU5402, PD173074, AZD1480, AZD4547 and BGJ398 compromises the use of small chemicals targeting FGFR catalytic activity for therapy of short-stature syndromes.

    Science.gov (United States)

    Gudernova, Iva; Vesela, Iva; Balek, Lukas; Buchtova, Marcela; Dosedelova, Hana; Kunova, Michaela; Pivnicka, Jakub; Jelinkova, Iva; Roubalova, Lucie; Kozubik, Alois; Krejci, Pavel

    2016-01-01

    Activating mutations in the fibroblast growth factor receptor 3 (FGFR3) cause the most common genetic form of human dwarfism, achondroplasia (ACH). Small chemical inhibitors of FGFR tyrosine kinase activity are considered to be viable option for treating ACH, but little experimental evidence supports this claim. We evaluated five FGFR tyrosine kinase inhibitors (TKIs) (SU5402, PD173074, AZD1480, AZD4547 and BGJ398) for their activity against FGFR signaling in chondrocytes. All five TKIs strongly inhibited FGFR activation in cultured chondrocytes and limb rudiment cultures, completely relieving FGFR-mediated inhibition of chondrocyte proliferation and maturation. In contrast, TKI treatment of newborn mice did not improve skeletal growth and had lethal toxic effects on the liver, lungs and kidneys. In cell-free kinase assays as well as in vitro and in vivo cell assays, none of the tested TKIs demonstrated selectivity for FGFR3 over three other FGFR tyrosine kinases. In addition, the TKIs exhibited significant off-target activity when screened against a panel of 14 unrelated tyrosine kinases. This was most extensive in SU5402 and AZD1480, which inhibited DDR2, IGF1R, FLT3, TRKA, FLT4, ABL and JAK3 with efficiencies similar to or greater than those for FGFR. Low target specificity and toxicity of FGFR TKIs thus compromise their use for treatment of ACH. Conceptually, different avenues of therapeutic FGFR3 targeting should be investigated.

  1. Drug design, synthesis, in vitro and in silico evaluation of selective monoaminoxidase B inhibitors based on 3-acetyl-2-dichlorophenyl-5-aryl-2,3-dihydro-1,3,4-oxadiazole chemical scaffold.

    Science.gov (United States)

    Distinto, Simona; Meleddu, Rita; Yanez, Matilde; Cirilli, Roberto; Bianco, Giulia; Sanna, Maria Luisa; Arridu, Antonella; Cossu, Pietro; Cottiglia, Filippo; Faggi, Cristina; Ortuso, Francesco; Alcaro, Stefano; Maccioni, Elias

    2016-01-27

    With the aim to identify new, potent and selective monoamine oxidase B (MAO-B) inhibitors, molecular interaction field analysis has been applied to a MAO-B complex with 3-acetyl-2,5-diaryl-2,3-dihydro-1,3,4-oxadiazole chemical structure, known as a privileged scaffold for this target. Several compounds displayed potent in vitro activity, exhibiting IC50 values in the medium to low nanomolar range. The enantiomers of most promising derivatives were separated by enantioselective HPLC and in vitro evaluated. Experimental results, according to theoretical drug design, clearly indicated a key role of the ligand stereochemistry in the target recognition/inhibition. In particular the (R)- enantiomers showed the best activity with respect to the (S)- stereoisomer. Finally, docking experiments coupled to molecular dynamics (MD) simulations, were applied for understanding the putative MAO -B binding modes of the new compounds providing detailed information for further structural optimization.

  2. A disorder-induced domino-like destabilization mechanism governs the folding and functional dynamics of the repeat protein IκBα.

    Directory of Open Access Journals (Sweden)

    Srinivasan Sivanandan

    Full Text Available The stability of the repeat protein IκBα, a transcriptional inhibitor in mammalian cells, is critical in the functioning of the NF-κB signaling module implicated in an array of cellular processes, including cell growth, disease, immunity and apoptosis. Structurally, IκBα is complex, with both ordered and disordered regions, thus posing a challenge to the available computational protocols to model its conformational behavior. Here, we introduce a simple procedure to model disorder in systems that undergo binding-induced folding that involves modulation of the contact map guided by equilibrium experimental observables in combination with an Ising-like Wako-Saitô-Muñoz-Eaton model. This one-step procedure alone is able to reproduce a variety of experimental observables, including ensemble thermodynamics (scanning calorimetry, pre-transitions, m-values and kinetics (roll-over in chevron plot, intermediates and their identity, and is consistent with hydrogen-deuterium exchange measurements. We further capture the intricate distance-dynamics between the domains as measured by single-molecule FRET by combining the model predictions with simple polymer physics arguments. Our results reveal a unique mechanism at work in IκBα folding, wherein disorder in one domain initiates a domino-like effect partially destabilizing neighboring domains, thus highlighting the effect of symmetry-breaking at the level of primary sequences. The offshoot is a multi-state and a dynamic conformational landscape that is populated by increasingly partially folded ensembles upon destabilization. Our results provide, in a straightforward fashion, a rationale to the promiscuous binding and short intracellular half-life of IκBα evolutionarily engineered into it through repeats with variable stabilities and expand the functional repertoire of disordered regions in proteins.

  3. Destabilizing Effects of Pore-Scale Disorder on Capillary Invasion in Partially-Wettable Porous Media

    CERN Document Server

    Holtzman, Ran

    2016-01-01

    We present a systematic, quantitative assessment of the impact of pore size disorder and its interplay with flow rates and the wettability on immiscible fluid displacement. Pore-scale simulations and micromodel experiments show that increasing disorder destabilizes the displacement, reducing the its efficiency and increasing the fluid-fluid interfacial area, by enhancing trapping at low rates, and fingering at high rates. Lowering disorder enhances the effect of the underlying lattice. Increasing wettability of the invading fluid (contact angle) stabilizes the invasion, smoothing the interface and inhibiting trapping--effects which are suppressed at low disorder and high rates.

  4. Mephisto - Research equipment for the study of solid/liquid interface destabilization in metal alloys

    Science.gov (United States)

    Favier, J. J.; Malmejac, Y.; Praizey, J. P.; Cambon, G.; Barillot, R.; Changeart, F. J.

    1982-09-01

    Preliminary results of a feasiblity study of space apparatus intended for solid/liquid destabilization in metal alloys, the Mephisto project, are presented. The phenomena that Mephisto will observe, the parameters it will measure, and the scientific studies that it will perform are stated. A general description is given of the instrument, its experimental tubes, and the experiment process. The environmental and thermal constraints, electrical characteristics, and the characteristics of the different signals are outlined. Finally, the requirements of the payload interfaces on which the equipment will be mounted are set forth, including mechanical/geometrical interfaces, thermal interfaces, and electrical interfaces.

  5. Substrate Phosphorylation and Feedback Regulation in JFK-promoted p53 Destabilization*

    OpenAIRE

    Sun, Luyang; SHI, LEI; Wang, Feng; Huangyang, Peiwei; Si, Wenzhe; Yang, Jie; Yao, Zhi; Shang, Yongfeng

    2010-01-01

    The p53 tumor suppressor plays a central role in integrating cellular responses to various stresses. Tight regulation of p53 is thus essential for the maintenance of genome integrity and normal cell proliferation. Previously, we reported that JFK, the only Kelch domain-containing F-box protein in human, promotes ubiquitination and degradation of p53 and that unlike the other E3 ligases for p53, all of which possess an intrinsic ubiquitin ligase activity, JFK destabilizes p53 through the assem...

  6. Thermodynamically destabilized hydride formation in "bulk" Mg-AlTi multilayers for hydrogen storage.

    Science.gov (United States)

    Kalisvaart, Peter; Shalchi-Amirkhiz, Babak; Zahiri, Ramin; Zahiri, Beniamin; Tan, XueHai; Danaie, Mohsen; Botton, Gianluigi; Mitlin, David

    2013-10-21

    Thermodynamic destabilization of MgH2 formation through interfacial interactions in free-standing Mg-AlTi multilayers of overall "bulk" (0.5 μm) dimensions with a hydrogen capacity of up to 5.5 wt% is demonstrated. The interfacial energies of Mg-AlTi and Mg-Ti (examined as a baseline) are calculated to be 0.81 and 0.44 J m(-2). The enhanced interfacial energy of AlTi opens the possibility of creating ultrathin alloy interlayers that provide further thermodynamic improvements in metal hydrides.

  7. Identification of a chemical inhibitor for nuclear speckle formation: Implications for the function of nuclear speckles in regulation of alternative pre-mRNA splicing

    Energy Technology Data Exchange (ETDEWEB)

    Kurogi, Yutaro; Matsuo, Yota; Mihara, Yuki; Yagi, Hiroaki; Shigaki-Miyamoto, Kaya; Toyota, Syukichi; Azuma, Yuko [Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555 (Japan); Igarashi, Masayuki [Laboratory of Disease Biology, Institute of Microbial Chemistry, Shinagawa-ku, Tokyo 141-0021 (Japan); Tani, Tokio, E-mail: ttani@sci.kumamoto-u.ac.jp [Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555 (Japan)

    2014-03-28

    Highlights: • We identified tubercidin as a compound inducing aberrant formation of the speckles. • Tubercidin causes delocalization of poly (A){sup +}RNAs from nuclear speckles. • Tubercidin induces dispersion of splicing factors from nuclear speckles. • Tubercidin affects alternative pre-mRNA splicing. • Nuclear speckles play a role in regulation of alternative pre-mRNA splicing. - Abstract: Nuclear speckles are subnuclear structures enriched with RNA processing factors and poly (A){sup +} RNAs comprising mRNAs and poly (A){sup +} non-coding RNAs (ncRNAs). Nuclear speckles are thought to be involved in post-transcriptional regulation of gene expression, such as pre-mRNA splicing. By screening 3585 culture extracts of actinomycetes with in situ hybridization using an oligo dT probe, we identified tubercidin, an analogue of adenosine, as an inhibitor of speckle formation, which induces the delocalization of poly (A){sup +} RNA and dispersion of splicing factor SRSF1/SF2 from nuclear speckles in HeLa cells. Treatment with tubercidin also decreased steady-state MALAT1 long ncRNA, thought to be involved in the retention of SRSF1/SF2 in nuclear speckles. In addition, we found that tubercidin treatment promoted exon skipping in the alternative splicing of Clk1 pre-mRNA. These results suggest that nuclear speckles play a role in modulating the concentration of splicing factors in the nucleoplasm to regulate alternative pre-mRNA splicing.

  8. Multilevel Precision-Based Rational Design of Chemical Inhibitors Targeting the Hydrophobic Cleft of Toxoplasma gondii Apical Membrane Antigen 1 (AMA1).

    Science.gov (United States)

    Vetrivel, Umashankar; Muralikumar, Shalini; Mahalakshmi, B; Lily Therese, K; Madhavan, H N; Alameen, Mohamed; Thirumudi, Indhuja

    2016-06-01

    Toxoplasma gondii is an intracellular Apicomplexan parasite and a causative agent of toxoplasmosis in human. It causes encephalitis, uveitis, chorioretinitis, and congenital infection. T. gondii invades the host cell by forming a moving junction (MJ) complex. This complex formation is initiated by intermolecular interactions between the two secretory parasitic proteins-namely, apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2) and is critically essential for the host invasion process. By this study, we propose two potential leads, NSC95522 and NSC179676 that can efficiently target the AMA1 hydrophobic cleft, which is a hotspot for targeting MJ complex formation. The proposed leads are the result of an exhaustive conformational search-based virtual screen with multilevel precision scoring of the docking affinities. These two compounds surpassed all the precision levels of docking and also the stringent post docking and cumulative molecular dynamics evaluations. Moreover, the backbone flexibility of hotspot residues in the hydrophobic cleft, which has been previously reported to be essential for accommodative binding of RON2 to AMA1, was also highly perturbed by these compounds. Furthermore, binding free energy calculations of these two compounds also revealed a significant affinity to AMA1. Machine learning approaches also predicted these two compounds to possess more relevant activities. Hence, these two leads, NSC95522 and NSC179676, may prove to be potential inhibitors targeting AMA1-RON2 complex formation towards combating toxoplasmosis.

  9. Multilevel Precision-Based Rational Design of Chemical Inhibitors Targeting the Hydrophobic Cleft of Toxoplasma gondii Apical Membrane Antigen 1 (AMA1)

    Science.gov (United States)

    Muralikumar, Shalini; Mahalakshmi, B; Lily Therese, K; Madhavan, HN; Alameen, Mohamed; Thirumudi, Indhuja

    2016-01-01

    Toxoplasma gondii is an intracellular Apicomplexan parasite and a causative agent of toxoplasmosis in human. It causes encephalitis, uveitis, chorioretinitis, and congenital infection. T. gondii invades the host cell by forming a moving junction (MJ) complex. This complex formation is initiated by intermolecular interactions between the two secretory parasitic proteins—namely, apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2) and is critically essential for the host invasion process. By this study, we propose two potential leads, NSC95522 and NSC179676 that can efficiently target the AMA1 hydrophobic cleft, which is a hotspot for targeting MJ complex formation. The proposed leads are the result of an exhaustive conformational search-based virtual screen with multilevel precision scoring of the docking affinities. These two compounds surpassed all the precision levels of docking and also the stringent post docking and cumulative molecular dynamics evaluations. Moreover, the backbone flexibility of hotspot residues in the hydrophobic cleft, which has been previously reported to be essential for accommodative binding of RON2 to AMA1, was also highly perturbed by these compounds. Furthermore, binding free energy calculations of these two compounds also revealed a significant affinity to AMA1. Machine learning approaches also predicted these two compounds to possess more relevant activities. Hence, these two leads, NSC95522 and NSC179676, may prove to be potential inhibitors targeting AMA1-RON2 complex formation towards combating toxoplasmosis. PMID:27445648

  10. Chemical modification of ascorbic acid and evaluation of its lipophilic derivatives as inhibitors of secretory phospholipase A(2) with anti-inflammatory activity.

    Science.gov (United States)

    Mohamed, Riyaz; Dharmappa, K K; Tarannum, Shaista; Jameel, N M; Kannum, S A; Ashrafulla, H S; Rai, Lokanath; Souza, Cletus Jmd'; Shekhar, M A; Vishwanath, Bannikuppe S

    2010-12-01

    The halo 6-fatty acid esters of L-ascorbic acid 3a, 3b and 6-fatty acid esters of L-ascorbic acid 5a-g were achieved from L-ascorbic acid 1. Compounds 3a, 3b and 5a-g were evaluated for anti-oxidant, anti-lipid peroxidation, and secretory phospholipase A(2) (sPLA(2)) inhibition in vitro, and sPLA(2) induced mouse paw edema. All the derivatives retained their anti-oxidant property compared to ascorbic acid at 6 × 10(-4)M and are good inhibitors of lipid peroxidation at 1 mg ml(-1) as evaluated by 2, 2-Diphenyl-1-picrylhydrazyl radical and thio-barbituric acid methods, respectively. Compounds 5e and 5f significantly inhibited purified group I sPLA(2) from Naja naja and group II sPLA(2) from Vipera russelli, human synovial fluid and human pleural fluid with IC(50) value ranging from 64 ± 1.95 to 82 ± 1.3 and 48 ± 2.27 to 61 ± 2.23 μM, respectively. The compounds 5e and 5f also showed varying degree of potency in neutralizing indirect hemolytic activity of sPLA(2) at 50 μM concentration, and sPLA(2) induced mouse paw edema at the dose 3 mg/kg. Further docking studies also confirmed that compounds 5e and 5f have maximum interaction with increasing negative energy value. Single molecule possessing both anti-oxidant and anti-inflammatory activities is of great therapeutic significance in inflammatory disorders.

  11. Parawixin2, a novel non-selective GABA uptake inhibitor from Parawixia bistriata spider venom, inhibits pentylenetetrazole-induced chemical kindling in rats.

    Science.gov (United States)

    Gelfuso, Erica A; Liberato, José L; Cunha, Alexandra O S; Mortari, Márcia R; Beleboni, Renê O; Lopes, Norberto P; Dos Santos, Wagner F

    2013-05-24

    The aims of the present work were to investigate the effects of the repeated administration of Parawixin2 (2-amino-5-ureidopentanamide; formerly FrPbAII), a novel GABA and glycine uptake inhibitor, in rats submitted to PTZ-induced kindling. Wistar rats were randomly divided in groups (n=6-8) for different treatments. Systemic injections of PTZ were administered every 48 h in the dose of 33 mg/kg; i.p., that is sufficient to induce fully kindled seizures in saline i.c.v. treated rats in a short period of time (28 days). Treatments in two types of positive controls (diazepam - DZP and nipecotic acid - NA groups) consisted in daily systemic injections of DZP (2mg/kg; i.p.) or i.c.v. injections of NA (12 μg/μL), while in experimental groups in daily i.c.v. injections of different doses of Parawixin2 (0.15; 0.075; 0.015 μg/μL). Seizures were analyzed using the Lamberty & Klitgaard score and kindling was considered as established after at least three consecutive seizures of score 4 or 5. Cumulative seizure scores for each group were analyzed using repeated measures of ANOVA followed by Tukey test. PTZ induced 4 and 5-score seizures after 12 injections in saline treated rats, whereas daily injection of Parawixin2 inhibited the onset of seizures in a dose dependent manner. Also, the challenging administration of PTZ did not raise seizure score in animals treated with the highest dose of Parawixin2 or those treated with DZP or NA. These findings together with previous data from our laboratory show that Parawixin2 could be a useful probe to design new antiepileptic drugs.

  12. Optimizing and slope determination of final wall for Maiduk Mine with consideration of destabilizer factors

    Institute of Scientific and Technical Information of China (English)

    Shamsoddin Saeed Masoud; Maarefvand Parviz; Yaaghubi Ebrahim

    2016-01-01

    In this research, determination of final slope for Maiduk copper mine of Kerman is investigated according to destabilizing factors of the mine. The development of the Maiduk Mine caused the extension of the mine area and also withdrawal of its wall. So, optimizing possibility of mine slope is essential. Finally, the magnitude of optimized slopes for different walls of the mine in association with executive com-mands with better factors of safety is provided. The results show that the most important destabilizer factors are the presence of water and pore pressure in the faults and the main joints. With the omission of pore pressure, mine wall for the designed depth is quite stable. This requires a drainage pattern in the lifetime of the mine. In an optimistic point of view, the minimum factor of safety of the wall will be 2.81 even without drainage. This conclusion allows optimizing the slope to its maximum magnitude of 51 degree. With the pessimistic engineering judgment and with the higher SF, the magnitude of the slope is optimized to 47 degree.

  13. URGENT DESTABILIZERS OF PUBLIC AND STATE SECURITY, TACTICS OF COUNTERACTION TO IT

    Directory of Open Access Journals (Sweden)

    D. N. Marinkin

    2016-01-01

    Full Text Available At creation of civil society in any constitutional state there is a crime counteraction problem. In the modern Russian Federation safety problems from the negative social phenomena and processes force scientists, public agents and ordinary citizens to investigate constantly such determinants and the reasons (destabilizers of safety of society and the constitutional state, to eliminate their consequences. Such problems as are urgent now: increase in information on ways and consequences of violence in the mass media (MM, the Internet, computer games, traditional physical abuse. The number of questions and assessment by citizens of consequences of the conducted terrorist attacks and infringement of life of citizens causes. The accounting of the specified problems and versions of decisions in law-enforcement practice, will allow to promote as a result efficiency of prevention of offenses and crimes and will bring closer modern Russia to ideal model of the constitutional state with real civil society. In article the author designates a number of the legal and social destabilizers of safety existing now in the Russian society and the state, proposes the solution of their negative impact on society within tactics of crime control.

  14. Transformation and destabilization of graphene oxide in reducing aqueous solutions containing sulfide.

    Science.gov (United States)

    Fu, Heyun; Qu, Xiaolei; Chen, Wei; Zhu, Dongqiang

    2014-12-01

    The colloidal stability of carbon nanomaterials is a key factor controlling their fate and bioavailability in natural aquatic systems. The authors report that graphene oxide nanoparticles could be destabilized in reducing aqueous solutions containing a low concentration (0.5 mM) of sulfide, a naturally occurring reductant. Spectroscopic characterization using combined X-ray photoelectron, Fourier-transform infrared, X-ray diffraction, and Raman analyses revealed that the surface oxygen-containing groups (mainly epoxy groups) of graphene oxide were significantly reduced after reacting with sodium sulfide. The destabilization of graphene oxide was likely caused by the enhanced surface hydrophobicity of the reduced graphene oxide, whereas electrostatic repulsion played a minimal role. Solution pH was found to affect both the deoxygenation process and the aggregation behavior of graphene oxide. Coexisting humic acid reduced the reaction efficiency and stabilized graphene oxide through steric hindrance. These findings suggest for the first time that the colloidal behavior of carbon nanomaterials might change drastically when they enter natural reducing environments containing sulfide such as anaerobic aquifers and sediments.

  15. Prediction of protein-destabilizing polymorphisms by manual curation with protein structure.

    Directory of Open Access Journals (Sweden)

    Craig Alan Gough

    Full Text Available The relationship between sequence polymorphisms and human disease has been studied mostly in terms of effects of single nucleotide polymorphisms (SNPs leading to single amino acid substitutions that change protein structure and function. However, less attention has been paid to more drastic sequence polymorphisms which cause premature termination of a protein's sequence or large changes, insertions, or deletions in the sequence. We have analyzed a large set (n = 512 of insertions and deletions (indels and single nucleotide polymorphisms causing premature termination of translation in disease-related genes. Prediction of protein-destabilization effects was performed by graphical presentation of the locations of polymorphisms in the protein structure, using the Genomes TO Protein (GTOP database, and manual annotation with a set of specific criteria. Protein-destabilization was predicted for 44.4% of the nonsense SNPs, 32.4% of the frameshifting indels, and 9.1% of the non-frameshifting indels. A prediction of nonsense-mediated decay allowed to infer which truncated proteins would actually be translated as defective proteins. These cases included the proteins linked to diseases inherited dominantly, suggesting a relation between these diseases and toxic aggregation. Our approach would be useful in identifying potentially aggregation-inducing polymorphisms that may have pathological effects.

  16. On the destabilizing effect of damping on discrete and continuous circulatory systems

    Science.gov (United States)

    Luongo, Angelo; D`Annibale, Francesco

    2014-12-01

    The 'Ziegler paradox', concerning the destabilizing effect of damping on elastic systems loaded by nonconservative positional forces, is addressed. The paper aims to look at the phenomenon in a new perspective, according to which no surprising discontinuities in the critical load exist between undamped and damped systems. To show that the actual critical load is found as an (infinitesimal) perturbation of one of the infinitely many sub-critically loaded undamped systems. A series expansion of the damped eigenvalues around the distinct purely imaginary undamped eigenvalues is performed, with the load kept as a fixed, although unknown, parameter. The first sensitivity of the eigenvalues, which is found to be real, is zeroed, so that an implicit expression for the critical load multiplier is found, which only depends on the 'shape' of damping, being independent of its magnitude. An interpretation is given of the destabilization paradox, by referring to the concept of 'modal damping', according to which the sign of the projection of the damping force on the eigenvector of the dual basis, and not on the eigenvector itself, is the true responsible for stability. The whole procedure is explained in detail for discrete systems, and successively extended to continuous systems. Two sample structures are studied for illustrative purposes: the classical reverse double-pendulum under a follower force and a linear visco-elastic beam under a follower force and a dead load.

  17. Thermodynamic and kinetic destabilization of magnesium hydride using Mg-In solid solution alloys.

    Science.gov (United States)

    Zhou, Chengshang; Fang, Zhigang Zak; Lu, Jun; Zhang, Xiaoyi

    2013-07-31

    Efforts to thermodynamically destabilize magnesium hydride (MgH2), so that it can be used for practical hydrogen storage applications, have been a difficult challenge that has eluded scientists for decades. This letter reports that MgH2 can indeed be destabilized by forming solid solution alloys of magnesium with group III and IVB elements, such as indium. Results of this research showed that the equilibrium hydrogen pressure of a Mg-0.1In alloy is 70% higher than that of pure MgH2. The temperature at 1 bar hydrogen pressure (T1bar) of Mg-0.1In alloy was reduced to 262.9 °C from 278.9 °C, which is the T1bar of pure MgH2. Furthermore, the kinetic rates of dehydrogenation of Mg-0.1In alloy hydride doped with a titanium intermetallic (TiMn2) catalyst were also significantly improved compared with those of MgH2.

  18. Design, synthesis, quantum chemical studies and biological activity evaluation of pyrazole-benzimidazole derivatives as potent Aurora A/B kinase inhibitors.

    Science.gov (United States)

    Zheng, Youguang; Zheng, Ming; Ling, Xin; Liu, Yi; Xue, Yunsheng; An, Lin; Gu, Ning; Ji, Min; Jin, Min

    2013-06-15

    Novel pyrazole-benzimidazole derivatives have been designed and synthesized. The entire target compounds were determined against cancer cell lines U937, K562, A549, LoVo and HT29 and were screened for Aurora A/B kinase inhibitory activity in vitro. The compounds 7a, 7b, 7i, 7k and 7l demonstrated significant cancer cell lines and Aurora A/B kinase inhibitory activities. Molecular modeling studies suggested the derivatives have bound in the active site of Aurora A kinase through the formation of four hydrogen bonds. Quantum chemical studies were carried out on these compounds to understand the structural features essential for activity. The cellular activity of 7k was also tested by immunofluorescence.

  19. Quantum chemical modeling of adsorption of ureides, that used as inhibitor of microbiological corrosion, on the iron of st3s grade of steel

    Directory of Open Access Journals (Sweden)

    Andrei Sikachina

    2016-07-01

    Full Text Available In published work presents modeled using quantum chemical package HyperChem version 8.0.7 using the semiempirical method ZINDO/1, the process of adsorption of organic compounds of ureidе ranging from simple to more complex, a cluster of iron (present in the steel in amounts of 97%. This approach, as will be shown, with high accuracy reflects the process of corrosion protection with bacterial content by chemisorption of organic compounds on the metal surface with the formation of complex compounds. In the research process were obtained and analyzed global and local electrophilicity heteroatoms, reflects the composition of the complexes, lit a graph showing the dependence of the local electrophilicity from protective anti-corrosion effect.

  20. 铜化学机械抛光中复合缓蚀剂的作用机制%Mechanisms of Mixed Corrosion Inhibitors in Copper Chemical Mechanical Polishing

    Institute of Scientific and Technical Information of China (English)

    龚桦; 王宁; 顾忠华; 潘国顺

    2013-01-01

    将复合缓蚀剂(苯并三氮唑(BTAH)和十二烷基磺酸钠(SDS))应用到铜的化学机械抛光液中,考察BTAH和SDS对铜表面化学机械抛光的影响,并探讨BTAH和SDS在铜表面的作用机制;分析BTAH和SDS抛光液中络合剂和表面活性剂对铜化学机械抛光性能的影响。结果表明:BTAH和SDS在铜表面形成了致密的Cu-BTAH和Cu-SDS保护膜,是优良的铜缓蚀剂。当以磷酸氢二胺(AHP)为络合剂,羟乙基纤维素(HEC)为表面活性剂时,优化后的BTAH和SDS抛光液取得了低至Ra0.2 nm的表面粗糙度,同时发现HEC有降低纳米颗粒残留的作用。%Mixed corrosion inhibitors(benzotriazole(BTAH)and sodium dodecyl sulfate(SDS))were utilized in copper chemical mechanical polishing(CMP)slurry.The influences of BTAH and SDS,complexing agent,and surfactant on the CMP of copper were studied,and the mechanisms of BTAH and SDS on copper surface were discussed.The results show that compact Cu-BTAH and Cu-SDS protective films are formed on the copper surface,and thus,which are excellent copper corrosion inhibitors.When using BTAH and SDS as mixed corrosion inhibitors,ammonium phosphate(AHP)as complexing agent,and hydroxy ethyl cellulose(HEC)as surfactant,a low surface roughness of 0.2 nm is got by this CMP slurry.The appearance of HEC in the slurry is found to be very effective in reducing the nano-sized particle deposition on copper surface.

  1. Transmission stabilization and destabilization involving Kerr and Raman effects in broadband soliton-based fiber optics systems

    CERN Document Server

    Peleg, Avner; Tran, Thinh P

    2015-01-01

    We study stabilization and destabilization of propagating soliton sequences in broadband fiber optics systems with $N$ frequency channels, taking into account second-order dispersion, Kerr nonlinearity, delayed Raman response, and linear gain-loss. We employ a propagation model consisting of a system of $N$ coupled nonlinear Schr\\"odinger (NLS) equations and a reduced $N$-dimensional predator-prey model for amplitude dynamics. Numerical simulations with the coupled-NLS model with $2 \\le N \\le 4$ show stable oscillatory dynamics of soliton amplitudes at short-to-intermediate distances, in agreement with predictions of the predator-prey model. Furthermore, the main destabilizing mechanism at long distances is due to generation of radiative sidebands, where the sidebands for a given channel form at the frequencies of solitons in the neighboring channels. This destabilizing process can be partially mitigated by employing frequency dependent linear gain-loss. Moreover, significant enhancement of transmission stabi...

  2. Synthesis, chemical characterization, computational studies and biological activity of new DNA methyltransferases (DNMTs) specific inhibitor. Epigenetic regulation as a new and potential approach to cancer therapy.

    Science.gov (United States)

    Pellerito, C; Morana, O; Ferrante, F; Calvaruso, G; Notaro, A; Sabella, S; Fiore, T

    2015-09-01

    This work deals with the synthesis, the chemical characterization of dibutyltin(IV) complex of caffeic acid (Bu2Sn(IV)HCAF, caf1) and its cytotoxic action on tumor cells. The coordination environment at the tin center was investigated by FTIR, (119)Sn{(1)H} cross polarization magic angle spinning, electrospray ionization mass spectroscopy in the solid state and UV-vis, fluorescence and (1)H, (13)C and (119)Sn NMR spectroscopy in solution phases. Density functional theory study confirmed the proposed structures in solution phase and indicated the most probably stable conformation. The effects on viability of breast cancer MDA-MB231, colorectal cancer HCT116, hepatocellular carcinoma HepG2 and Chang liver cells, an immortalized non-tumor hepatic cell line, have been investigated. The effect of a variation in structure of caf1 was found to lead to a change in the respective antiproliferative properties: caf1 induces loss of viability in HCT116, MDA-MB-231, and HepG2; the complex shows only moderate effects in non-tumor Chang liver cells. caf1 exerts lower cytotoxic activity than Bu2SnCl2, suggesting that the binding with H3CAF modulates the marked cytotoxic activity exerted by Bu2SnCl2; caf1 displays a considerably more pronounced antitumoural effect towards cell lines than caffeic acid. It is known that caffeic acid can modulate DNA (cytosine-5)-methyltransferases 1 (DNMT1) mediated DNA methylation. In this paper we demonstrate that caf1 treatment was able to induce a time-dependent reduction of global DNA methylated status. This effect was also confirmed by a concomitant reduction DNMT1 expression level. The effect induced by caf1 was more evident not only with respect to untreated cells but also compared to H3CAF treated cells.

  3. Engineering FKBP-Based Destabilizing Domains to Build Sophisticated Protein Regulation Systems.

    Directory of Open Access Journals (Sweden)

    Wenlin An

    Full Text Available Targeting protein stability with small molecules has emerged as an effective tool to control protein abundance in a fast, scalable and reversible manner. The technique involves tagging a protein of interest (POI with a destabilizing domain (DD specifically controlled by a small molecule. The successful construction of such fusion proteins may, however, be limited by functional interference of the DD epitope with electrostatic interactions required for full biological function of proteins. Another drawback of this approach is the remaining endogenous protein. Here, we combined the Cre-LoxP system with an advanced DD and generated a protein regulation system in which the loss of an endogenous protein, in our case the tumor suppressor PTEN, can be coupled directly with a conditionally fine-tunable DD-PTEN. This new system will consolidate and extend the use of DD-technology to control protein function precisely in living cells and animal models.

  4. Four-Rod Stabilization of Severely Destabilized Lumbar Spine Caused by Metastatic Tumor

    Directory of Open Access Journals (Sweden)

    Isao Shibuya

    2013-01-01

    Full Text Available We report a case of a 67-year-old female with severely destabilized lumbar spine caused by metastatic malignant tumor. The primary lesion was a thyroid follicular adenocarcinoma. Complete destruction of the L3, L4, and L5 vertebrae had resulted in severe instability, which left the patient with severe back pain and bed-ridden. Since the vertebrae were so severely damaged at 3 levels, 4 rods were used to stabilize the spine. Following stabilization, the pain was alleviated and the patient’s quality of life improved. We introduce here the 4-rod technique to stabilize the spine over 3 vertebral levels following severe destruction by metastatic tumor.

  5. Formation and Destabilization of the Particle Band on the Fluid-Fluid Interface

    Science.gov (United States)

    Kim, Jungchul; Xu, Feng; Lee, Sungyon

    2017-02-01

    An inclusion of particles in a Newtonian liquid can fundamentally change the interfacial dynamics and even cause interfacial instabilities. For instance, viscous fingering can arise even in the absence of the destabilizing viscosity ratio between invading and defending phases, when particles are added to the viscous invading fluid inside a Hele-Shaw cell. In the same flow configuration, the formation and breakup of a dense particle band are observed on the interface, only when the particle diameter d becomes comparable to the channel gap thickness h . We experimentally characterize the evolution of the fluid-fluid interface in this new physical regime and propose a simple model for the particle band that successfully captures the fingering onset as a function of the particle concentration and h /d .

  6. A Destabilized Case of Stable Effort Angina Pectoris Induced by Low-dose Adenosine Triphosphate

    Science.gov (United States)

    Sueta, Daisuke; Kojima, Sunao; Izumiya, Yasuhiro; Yamamuro, Megumi; Kaikita, Koichi; Hokimoto, Seiji; Ogawa, Hisao

    2016-01-01

    A 79-year-old man was diagnosed with sudden deafness. He had previously experienced a suspected episode of angina pectoris. At a local hospital, after 500 mg of hydrocortisone and 80 mg adenosine triphosphate (ATP) were administered, he became aware of chest discomfort. An electrocardiogram revealed serious ST-segment depressions. He was diagnosed with a non-ST elevated myocardial infarction (NSTEMI). Emergency coronary angiography revealed triple vessel disease, and the lesion was successfully stented. The mechanisms whereby the stable effort angina pectoris destabilized in this case were thought to include a reduction of the local blood flow because of an ATP product and probable thrombus formation in response to the administered steroids. PMID:27853071

  7. Numerical studies of gravity destabilized percolation in 2D porous media

    Science.gov (United States)

    Bo, Z.; Loggia, D.; Xiaorong, L.; Vasseur, G.; Ping, H.

    2006-04-01

    Two dimensional simulations of percolation are realized on square networks of pore throats with a random capillary pressure distribution. We analyse the influence of a destabilizing gravity field (g) and of the standard deviation of the distribution of the capillary pressure thresholds (Wt). The fragmentation process is not taken into account in this study. For an increase of g or/and when Wt decreases, two transitions are analyzed with three different regimes displacement patterns: Invasion percolation, invasion percolation in a gradient, and invasion in a pure gradient. The transitions are controlled both by the ratio g/Wt and by the sample size (L). A scaling law between the saturation at the percolation threshold and g/Wt allows delineating the three regimes in agreement with theoretical argument of the percolation in a gradient.

  8. The mass media destabilizes the cultural homogenous regime in Axelrod's model

    Energy Technology Data Exchange (ETDEWEB)

    Peres, Lucas R; Fontanari, Jose F [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, 13560-970 Sao Carlos SP (Brazil)

    2010-02-05

    An important feature of Axelrod's model for culture dissemination or social influence is the emergence of many multicultural absorbing states, despite the fact that the local rules that specify the agents interactions are explicitly designed to decrease the cultural differences between agents. Here we re-examine the problem of introducing an external, global interaction-the mass media-in the rules of Axelrod's model: in addition to their nearest neighbors, each agent has a certain probability p to interact with a virtual neighbor whose cultural features are fixed from the outset. Most surprisingly, this apparently homogenizing effect actually increases the cultural diversity of the population. We show that, contrary to previous claims in the literature, even a vanishingly small value of p is sufficient to destabilize the homogeneous regime for very large lattice sizes.

  9. Mechanism for the catastrophe-promoting activity of the microtubule destabilizer Op18/stathmin.

    Science.gov (United States)

    Gupta, Kamlesh K; Li, Chunlei; Duan, Aranda; Alberico, Emily O; Kim, Oleg V; Alber, Mark S; Goodson, Holly V

    2013-12-17

    Regulation of microtubule dynamic instability is crucial for cellular processes, ranging from mitosis to membrane transport. Stathmin (also known as oncoprotein 18/Op18) is a prominent microtubule destabilizer that acts preferentially on microtubule minus ends. Stathmin has been studied intensively because of its association with multiple types of cancer, but its mechanism of action remains controversial. Two models have been proposed. One model is that stathmin promotes microtubule catastrophe indirectly, and does so by sequestering tubulin; the other holds that stathmin alters microtubule dynamics by directly destabilizing growing microtubules. Stathmin's sequestration activity is well established, but the mechanism of any direct action is mysterious because stathmin binds to microtubules very weakly. To address these issues, we have studied interactions between stathmin and varied tubulin polymers. We show that stathmin binds tightly to Dolastatin-10 tubulin rings, which mimic curved tubulin protofilaments, and that stathmin depolymerizes stabilized protofilament-rich polymers. These observations lead us to propose that stathmin promotes catastrophe by binding to and acting upon protofilaments exposed at the tips of growing microtubules. Moreover, we suggest that stathmin's minus-end preference results from interactions between stathmin's N terminus and the surface of α-tubulin that is exposed only at the minus end. Using computational modeling of microtubule dynamics, we show that these mechanisms could account for stathmin's observed activities in vitro, but that both the direct and sequestering activities are likely to be relevant in a cellular context. Taken together, our results suggest that stathmin can promote catastrophe by direct action on protofilament structure and interactions.

  10. Evidence of sheared sills related to flank destabilization in a basaltic volcano

    Science.gov (United States)

    Berthod, C.; Famin, V.; Bascou, J.; Michon, L.; Ildefonse, B.; Monié, P.

    2016-04-01

    Piton des Neiges basaltic volcano (La Réunion) has been deeply dissected by erosion, exposing large volumes of debris avalanche deposits. To shed light on the factors that led to volcano flank destabilizations, we studied the structure, the crystallographic and magnetic fabrics of the substratum of a debris avalanche unit. This substratum is a complex of > 50 seaward-dipping sills that has been exposed by the avalanche. Structural observations show that the sill plane in contact with the avalanche is one of the latest intrusions in the sill complex. In this uppermost sill, the anisotropy of magnetic susceptibility (AMS) is correlated to the crystallographic preferred orientation of magmatic silicate minerals, allowing us to use AMS as a proxy to infer the magmatic flow. The AMS fabric across the intrusion is strongly asymmetric, which reveals that the contact sill was emplaced with a normal shear displacement of its hanging wall. The shear displacement and the magma flow in the intrusion are both directed toward the NNE, i.e. toward the sea, which is also the direction of the slope and of the debris avalanche runout. Because all the sills in the intrusion complex have a similar dip and dip direction, it is likely that several of them also underwent a cointrusive slip toward the NNE. We conclude that this cointrusive normal slip, repeated over many intrusions of the sill complex, increased the flank instability of the volcano. This incremental instability may have ended up into the observed debris avalanche deposit. At Piton de la Fournaise, the active volcano of La Réunion, sill intrusion and cointrusive flank displacement have been inferred from geophysical studies for the April 2007 eruption. By providing direct evidence of sheared sills, our study substantiates the idea that repeated sill intrusions may eventually trigger flank destabilizations in basaltic volcanoes.

  11. Destabilizing protein polymorphisms in the genetic background direct phenotypic expression of mutant SOD1 toxicity.

    Directory of Open Access Journals (Sweden)

    Tali Gidalevitz

    2009-03-01

    Full Text Available Genetic background exerts a strong modulatory effect on the toxicity of aggregation-prone proteins in conformational diseases. In addition to influencing the misfolding and aggregation behavior of the mutant proteins, polymorphisms in putative modifier genes may affect the molecular processes leading to the disease phenotype. Mutations in SOD1 in a subset of familial amyotrophic lateral sclerosis (ALS cases confer dominant but clinically variable toxicity, thought to be mediated by misfolding and aggregation of mutant SOD1 protein. While the mechanism of toxicity remains unknown, both the nature of the SOD1 mutation and the genetic background in which it is expressed appear important. To address this, we established a Caenorhabditis elegans model to systematically examine the aggregation behavior and genetic interactions of mutant forms of SOD1. Expression of three structurally distinct SOD1 mutants in C. elegans muscle cells resulted in the appearance of heterogeneous populations of aggregates and was associated with only mild cellular dysfunction. However, introduction of destabilizing temperature-sensitive mutations into the genetic background strongly enhanced the toxicity of SOD1 mutants, resulting in exposure of several deleterious phenotypes at permissive conditions in a manner dependent on the specific SOD1 mutation. The nature of the observed phenotype was dependent on the temperature-sensitive mutation present, while its penetrance reflected the specific combination of temperature-sensitive and SOD1 mutations. Thus, the specific toxic phenotypes of conformational disease may not be simply due to misfolding/aggregation toxicity of the causative mutant proteins, but may be defined by their genetic interactions with cellular pathways harboring mildly destabilizing missense alleles.

  12. Molecular insight into amyloid oligomer destabilizing mechanism of flavonoid derivative 2-(4' benzyloxyphenyl)-3-hydroxy-chromen-4-one through docking and molecular dynamics simulations.

    Science.gov (United States)

    Kumar, Akhil; Srivastava, Swati; Tripathi, Shubhandra; Singh, Sandeep Kumar; Srikrishna, Saripella; Sharma, Ashok

    2016-06-01

    Aggregation of amyloid peptide (Aβ) has been shown to be directly related to progression of Alzheimer's disease (AD). Aβ is neurotoxic and its deposition and aggregation ultimately lead to cell death. In our previous work, we reported flavonoid derivative (compound 1) showing promising result in transgenic AD model of Drosophila. Compound 1 showed prevention of Aβ-induced neurotoxicity and neuroprotective efficacy in Drosophila system. However, mechanism of action of compound 1 and its effect on the amyloid is not known. We therefore performed molecular docking and atomistic, explicit-solvent molecular dynamics simulations to investigate the process of Aβ interaction, inhibition, and destabilizing mechanism. Results showed different preferred binding sites of compound 1 and good affinity toward the target. Through the course of 35 ns molecular dynamics simulation, conformations_5 of compound 1 intercalates into the hydrophobic core near the salt bridge and showed major structural changes as compared to other conformations. Compound 1 showed interference with the salt bridge and thus reducing the inter strand hydrogen bound network. This minimizes the side chain interaction between the chains A-B leading to disorder in oligomer. Contact map analysis of amino acid residues between chains A and B also showed lesser interaction with adjacent amino acids in the presence of compound 1 (conformations_5). The study provides an insight into how compound 1 interferes and disorders the Aβ peptide. These findings will further help to design better inhibitors for aggregation of the amyloid oligomer.

  13. Validation of merocyanine 540 staining as a technique for assessing capacitation-related membrane destabilization of fresh dog sperm

    NARCIS (Netherlands)

    Steckler, D; Stout, T A E; Durandt, C; Nöthling, J O

    2015-01-01

    The aim of this study was to determine whether flow cytometric evaluation of combined merocyanine 540 and Yo-Pro 1 (M540-YP) staining would identify viable dog sperm that had undergone membrane stabilization known to be associated with capacitation in other species, and whether such destabilization

  14. [Application of process engineering to remove lignocellulose fermentation inhibitors].

    Science.gov (United States)

    Wang, Lan; Xia, Menglei; Chen, Hongzhang

    2014-05-01

    Fermentation inhibitors are toxic to cells, which is one of the bottlenecks for lignocellulose bio-refinery process. How to remove those inhibitors serves a key role in the bioconversion of lignocellulose. This article reviews the sources and the types of the inhibitors, especially the updated removal strategies including physical methods, chemical methods, biological methods and inhibitor-tolerant strain construction strategies. Based on these, we introduce a new bio-refinery model named "fractional conversion", which reduces the production of inhibitors at pretreatment stage, and a novel in situ detoxification method named "fermentation promoter exploitation technology". This review could provide new research ideas on the removal of fermentation inhibitors.

  15. LFA-1 binding destabilizes the JAM-A homophilic interaction during leukocyte transmigration.

    Science.gov (United States)

    Wojcikiewicz, Ewa P; Koenen, Rory R; Fraemohs, Line; Minkiewicz, Julia; Azad, Hashem; Weber, Christian; Moy, Vincent T

    2009-01-01

    Leukocyte transendothelial migration into inflamed areas is regulated by the integrity of endothelial cell junctions and is stabilized by adhesion molecules including junctional adhesion molecule-A (JAM-A). JAM-A has been shown to participate in homophilic interactions with itself and in heterophilic interactions with leukocyte function-associated antigen-1 (LFA-1) via its first and second immunoglobulin domains, respectively. Using competitive binding assays in conjunction with atomic force microscopy adhesion measurements, we provide compelling evidence that the second domain of JAM-A stabilizes the homophilic interaction because its deletion suppresses the dynamic strength of the JAM-A homophilic interaction. Moreover, binding of the LFA-1 inserted domain to the second domain of JAM-A reduces the dynamic strength of the JAM-A homophilic interaction to the level measured with the JAM-A domain 2 deletion mutant. This finding suggests that LFA-1 binding cancels the stabilizing effects of the second immunoglobulin domain of JAM-A. Finally, our atomic force microscopy measurements reveal that the interaction of JAM-A with LFA-1 is stronger than the JAM-A homophilic interaction. Taken together, these results suggest that LFA-1 binding to JAM-A destabilizes the JAM-A homophilic interaction. In turn, the greater strength of the LFA-1/JAM-A complex permits it to support the tension needed to disrupt the JAM-A homophilic interaction, thus allowing transendothelial migration to proceed.

  16. Comparative analysis of the plant mRNA-destabilizing element, DST, in mammalian and tobacco cells.

    Science.gov (United States)

    Feldbrügge, M; Arizti, P; Sullivan, M L; Zamore, P D; Belasco, J G; Green, P J

    2002-05-01

    The labile SAUR transcripts from higher plants contain a conserved DST sequence in their 3'-untranslated regions. Two copies of a DST sequence from soybean are sufficient to destabilize reporter transcripts in cultured tobacco cells whereas variants bearing mutations in the conserved ATAGAT or GTA regions are inactive. To investigate the potential for conserved recognition components in mammalian and plant cells, we examined the function of this instability determinant in mouse NIH3T3 fibroblasts and tobacco BY2 cells. In fibroblasts, a tetrameric DST element from soybean accelerated deadenylation and decay of a reporter transcript. However, a version mutated in the ATAGAT region was equally effective in this regard, and a tetrameric DST element from Arabidopsis was inactive. In contrast, the soybean DST element was more active as an mRNA instability element than the mutant version and the Arabidopsis element, when tested as tetramers in tobacco cells. Hence, the plant DST element is not recognized in animal cells with the same sequence requirements as in plant cells. Therefore, its mode of recognition appears to be plant-specific.

  17. Space geodetic monitoring of engineered structures: The ongoing destabilization of the Mosul dam, Iraq

    Science.gov (United States)

    Milillo, Pietro; Bürgmann, Roland; Lundgren, Paul; Salzer, Jacqueline; Perissin, Daniele; Fielding, Eric; Biondi, Filippo; Milillo, Giovanni

    2016-12-01

    We present a detailed survey of the ongoing destabilization process of the Mosul dam. The dam is located on the Tigris river and is the biggest hydraulic structure in Iraq. From a geological point of view the dam foundation is poor due to a site geology formed by alternating strata of highly soluble materials including gypsum, anhydrite, marl and limestone. Here we present the first multi-sensor cumulative deformation map for the dam generated from space-based interferometric synthetic aperture radar measurements from the Italian constellation COSMO-SkyMed and the European sensor Sentinel-1a over the period 2014-2016 that we compare to an older dataset spanning 2004-2010 acquired with the European Envisat satellite. We found that deformation was rapid during 2004-2010, slowed in 2012-2014 and increased since August 2014 when grouting operations stopped due to the temporary capture of the dam by the self proclaimed Islamic State. We model the inferred deformation using a Markov chain Monte Carlo approach to solve for change in volume for simple tensile dislocations. Results from recent and historical geodetic datasets suggests that the volume dissolution rate remains constant when the equivalent volume of total concrete injected during re-grouting operations is included in the calculations.

  18. Cortisol and testosterone increase financial risk taking and may destabilize markets

    Science.gov (United States)

    Cueva, Carlos; Roberts, R. Edward; Spencer, Tom; Rani, Nisha; Tempest, Michelle; Tobler, Philippe N.; Herbert, Joe; Rustichini, Aldo

    2015-01-01

    It is widely known that financial markets can become dangerously unstable, yet it is unclear why. Recent research has highlighted the possibility that endogenous hormones, in particular testosterone and cortisol, may critically influence traders’ financial decision making. Here we show that cortisol, a hormone that modulates the response to physical or psychological stress, predicts instability in financial markets. Specifically, we recorded salivary levels of cortisol and testosterone in people participating in an experimental asset market (N = 142) and found that individual and aggregate levels of endogenous cortisol predict subsequent risk-taking and price instability. We then administered either cortisol (single oral dose of 100 mg hydrocortisone, N = 34) or testosterone (three doses of 10 g transdermal 1% testosterone gel over 48 hours, N = 41) to young males before they played an asset trading game. We found that both cortisol and testosterone shifted investment towards riskier assets. Cortisol appears to affect risk preferences directly, whereas testosterone operates by inducing increased optimism about future price changes. Our results suggest that changes in both cortisol and testosterone could play a destabilizing role in financial markets through increased risk taking behaviour, acting via different behavioural pathways. PMID:26135946

  19. Entropic (de)stabilization of surface-bound peptides conjugated with polymers.

    Science.gov (United States)

    Carmichael, Scott P; Shell, M Scott

    2015-12-28

    In many emerging biotechnologies, functional proteins must maintain their native structures on or near interfaces (e.g., tethered peptide arrays, protein coated nanoparticles, and amphiphilic peptide micelles). Because the presence of a surface is known to dramatically alter the thermostability of tethered proteins, strategies to stabilize surface-bound proteins are highly sought. Here, we show that polymer conjugation allows for significant control over the secondary structure and thermostability of a model surface-tethered peptide. We use molecular dynamics simulations to examine the folding behavior of a coarse-grained helical peptide that is conjugated to polymers of various lengths and at various conjugation sites. These polymer variations reveal surprisingly diverse behavior, with some stabilizing and some destabilizing the native helical fold. We show that ideal-chain polymer entropies explain these varied effects and can quantitatively predict shifts in folding temperature. We then develop a generic theoretical model, based on ideal-chain entropies, that predicts critical lengths for conjugated polymers to effect changes in the folding of a surface-bound protein. These results may inform new design strategies for the stabilization of surface-associated proteins important for a range technological applications.

  20. A Mutation Identified in Neonatal Microcephaly Destabilizes Zika Virus NS1 Assembly in Vitro

    Science.gov (United States)

    Wang, Deping; Chen, Cheng; Liu, Shengnan; Zhou, Han; Yang, Kailin; Zhao, Qi; Ji, Xiaoyun; Chen, Chen; Xie, Wei; Wang, Zefang; Mi, Li-Zhi; Yang, Haitao

    2017-01-01

    An unprecedented epidemic of Zika virus (ZIKV) infection had spread to South and Central America. ZIKV infection was recently confirmed by CDC (the Centers for Disease Control and Prevention) to cause neonatal microcephaly, which posed a significant public health emergency of international concern. No specific vaccines or drugs are currently available to fight ZIKV infection. ZIKV nonstructural protein 1 (NS1) plays an essential role in viral replication and immune evasion. We determined the crystal structure of ZIKV NS1172–352, which forms a head-to-head, symmetric dimer with a unique 14-stranded β-ladder conserved among flaviviruses. The assembly of the β-ladder dimer is concentration dependent. Strikingly, one pathogenic mutation T233A (NCBI accession no. KU527068), found in the brain tissue of infected fetus with neonatal microcephaly, is located at the dimer interface. Thr233, a unique residue found in ZIKV but not in other flaviviruses, organizes a central hydrogen bonding network at NS1 dimer interface. Mutation of Thr233 to Ala disrupts this elaborated interaction network, and destabilizes the NS1 dimeric assembly in vitro. In addition, our structural comparison of epitopes for protective antibody 22NS1, targeting West Nile Virus NS1, could potentially be valuable in understanding its anti-virus specificities and in the development of antibodies against ZIKV. PMID:28198446

  1. Entropic (de)stabilization of surface-bound peptides conjugated with polymers

    Science.gov (United States)

    Carmichael, Scott P.; Shell, M. Scott

    2015-12-01

    In many emerging biotechnologies, functional proteins must maintain their native structures on or near interfaces (e.g., tethered peptide arrays, protein coated nanoparticles, and amphiphilic peptide micelles). Because the presence of a surface is known to dramatically alter the thermostability of tethered proteins, strategies to stabilize surface-bound proteins are highly sought. Here, we show that polymer conjugation allows for significant control over the secondary structure and thermostability of a model surface-tethered peptide. We use molecular dynamics simulations to examine the folding behavior of a coarse-grained helical peptide that is conjugated to polymers of various lengths and at various conjugation sites. These polymer variations reveal surprisingly diverse behavior, with some stabilizing and some destabilizing the native helical fold. We show that ideal-chain polymer entropies explain these varied effects and can quantitatively predict shifts in folding temperature. We then develop a generic theoretical model, based on ideal-chain entropies, that predicts critical lengths for conjugated polymers to effect changes in the folding of a surface-bound protein. These results may inform new design strategies for the stabilization of surface-associated proteins important for a range technological applications.

  2. De-stabilization of the positive vago-vagal reflex in bulimia nervosa.

    Science.gov (United States)

    Faris, Patricia L; Hofbauer, Randall D; Daughters, Randall; Vandenlangenberg, Erin; Iversen, Laureen; Goodale, Robert L; Maxwell, Robert; Eckert, Elke D; Hartman, Boyd K

    2008-04-22

    Bulimia nervosa is characterized by consuming large amounts of food over a defined period with a loss of control over the eating. This is followed by a compensatory behavior directed at eliminating the consumed calories, usually vomiting. Current treatments include antidepressants and/or behavioral therapies. Consensus exists that these treatments are not very effective and are associated with high relapse rates. We review evidence from literature and present original data to evaluate the hypothesis that bulimia involves alterations in vago-vagal function. Evidence in support of this include (1) laboratory studies consistently illustrate deficits in meal size, meal termination, and satiety in bulimia; (2) basic science studies indicate that meal size and satiation are under vagal influences; (3) anatomical, behavioral and physiological data suggest that achieving satiety and the initiation of emesis involve common neural substrates; (4) abnormal vagal and vago-vagal reflexive functions extend to non-eating activational stimuli; and (5) studies from our laboratory modulating vagal activation have shown significant effects on binge/vomit frequencies and suggest a return of normal satiation. We propose a model for the pathophysiology of bulimia based upon de-stabilization of a bi-stable positive vago-vagal feedback loop. This model is not meant to be complete, but rather to stimulate anatomical, psychobiological, and translational neuroscience experiments aimed at elucidating the pathophysiology of bulimia and developing novel treatment strategies.

  3. EDTA-induced Membrane Fluidization and Destabilization: Biophysical Studies on Artificial Lipid Membranes

    Institute of Scientific and Technical Information of China (English)

    Virapong PRACHAYASITTIKUL; Chartchalerm ISARANKURA-NA-AYUDHYA; Tanawut TANTIMONGCOLWAT; Chanin NANTASENAMAT; Hans-Joachim GALLA

    2007-01-01

    The molecular mechanism of ethylenediaminetetraacetic acid (EDTA)-induced membrane destabilization has been studied using a combination of four biophysical techniques on artificial lipid membranes.Data from Langmuir film balance and epifluorescence microscopy revealed the fluidization and expansion effect of EDTA on phase behavior of monolayers of either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or mixtures of DPPC and metal-chelating lipids, such as Nα,Nα-Bis[carboxymethyl]-Nε-[(dioctadecylamino)succinyl]-L-lysine or 1,2-dioleoyl-sn-glycero-3-[N-(5-amino- 1-carboxypentyl iminodiacetic acid) succinyl]. A plausible explanation could be drawn from the electrostatic interaction between negatively charged groups of EDTA and the positively charged choline head group of DPPC.Intercalation of EDTA into the lipid membrane induced membrane curvature as elucidated by atomic force microscopy. Growth in size and shape of the membrane protrusion was found to be time-dependent upon exposure to EDTA. Further loss of material from the lipid membrane surface was monitored in real time using a quartz crystal microbalance. This indicates membrane restabilization by exclusion of the protrusions from the surface. Loss of lipid components facilitates membrane instability, leading to membrane permeabilization and lysis.

  4. Cortisol and testosterone increase financial risk taking and may destabilize markets.

    Science.gov (United States)

    Cueva, Carlos; Roberts, R Edward; Spencer, Tom; Rani, Nisha; Tempest, Michelle; Tobler, Philippe N; Herbert, Joe; Rustichini, Aldo

    2015-07-02

    It is widely known that financial markets can become dangerously unstable, yet it is unclear why. Recent research has highlighted the possibility that endogenous hormones, in particular testosterone and cortisol, may critically influence traders' financial decision making. Here we show that cortisol, a hormone that modulates the response to physical or psychological stress, predicts instability in financial markets. Specifically, we recorded salivary levels of cortisol and testosterone in people participating in an experimental asset market (N = 142) and found that individual and aggregate levels of endogenous cortisol predict subsequent risk-taking and price instability. We then administered either cortisol (single oral dose of 100 mg hydrocortisone, N = 34) or testosterone (three doses of 10 g transdermal 1% testosterone gel over 48 hours, N = 41) to young males before they played an asset trading game. We found that both cortisol and testosterone shifted investment towards riskier assets. Cortisol appears to affect risk preferences directly, whereas testosterone operates by inducing increased optimism about future price changes. Our results suggest that changes in both cortisol and testosterone could play a destabilizing role in financial markets through increased risk taking behaviour, acting via different behavioural pathways.

  5. A mechanistic study on the destabilization of whole inactivated influenza virus vaccine in gastric environment.

    Directory of Open Access Journals (Sweden)

    Hyo-Jick Choi

    Full Text Available Oral immunization using whole inactivated influenza virus vaccine promises an efficient vaccination strategy. While oral vaccination was hampered by harsh gastric environment, a systematic understanding about vaccine destabilization mechanisms was not performed. Here, we investigated the separate and combined effects of temperature, retention time, pH, and osmotic stress on the stability of influenza vaccine by monitoring the time-dependent morphological change using stopped-flow light scattering. When exposed to osmotic stress, clustering of vaccine particles was enhanced in an acidic medium (pH 2.0 at ≥25°C. Fluorescence spectroscopic studies showed that hyper-osmotic stress at pH 2.0 and 37°C caused a considerable increase in conformational change of antigenic proteins compared to that in acidic iso-osmotic medium. A structural integrity of membrane was destroyed upon exposure to hyper-osmotic stress, leading to irreversible morphological change, as observed by undulation in stopped-flow light scattering intensity and transmission electron microscopy. Consistent with these analyses, hemagglutination activity decreased more significantly with an increasing magnitude of hyper-osmotic stress than in the presence of the hypo- and iso-osmotic stresses. This study shows that the magnitude and direction of the osmotic gradient has a substantial impact on the stability of orally administrated influenza vaccine.

  6. Experimental Branch Retinal Vein Occlusion Induces Upstream Pericyte Loss and Vascular Destabilization.

    Directory of Open Access Journals (Sweden)

    Elisa Dominguez

    Full Text Available Branch retinal vein occlusion (BRVO leads to extensive vascular remodeling and is important cause of visual impairment. Although the vascular morphological changes following experimental vein occlusion have been described in a variety of models using angiography, the underlying cellular events are ill defined.We here show that laser-induced experimental BRVO in mice leads to a wave of TUNEL-positive endothelial cell (EC apoptosis in the upstream vascular network associated with a transient edema and hemorrhages. Subsequently, we observe an induction of EC proliferation within the dilated vein and capillaries, detected by EdU incorporation, and the edema resolves. However, the pericytes of the upstream capillaries are severely reduced, which was associated with continuing EC apoptosis and proliferation. The vascular remodeling was associated with increased expression of TGFβ, TSP-1, but also FGF2 expression. Exposure of the experimental animals to hypoxia, when pericyte (PC dropout had occurred, led to a dramatic increase in endothelial cell proliferation, confirming the vascular instability induced by the experimental BRVO.Experimental BRVO leads to acute endothelial cells apoptosis and increased permeability. Subsequently the upstream vascular network remains destabilized, characterized by pericyte dropout, un-physiologically high endothelial cells turnover and sensitivity to hypoxia. These early changes might pave the way for capillary loss and subsequent chronic ischemia and edema that characterize the late stage disease.

  7. Characterization of lysosome-destabilizing DOPE/PLGA nanoparticles designed for cytoplasmic drug release.

    Science.gov (United States)

    Chhabra, Resham; Grabrucker, Andreas M; Veratti, Patrizia; Belletti, Daniela; Boeckers, Tobias M; Vandelli, Maria Angela; Forni, Flavio; Tosi, Giovanni; Ruozi, Barbara

    2014-08-25

    Polymeric nanoparticles (NPs) offer a promising approach for therapeutic intracellular delivery of proteins, conventionally hampered by short half-lives, instability and immunogenicity. Remarkably, NPs uptake occurs via endocytic internalization leading to NPs content's release within lysosomes. To overcome lysosomal degradation and achieve NPs and/or loaded proteins release into cytosol, we propose the formulation of hybrid NPs by adding 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) as pH sensitive component in the formulation of poly-lactide-co-glycolide (PLGA) NPs. Hybrid NPs, featured by different DOPE/PLGA ratios, were characterized in terms of structure, stability and lipid organization within the polymeric matrix. Experiments on NIH cells and rat primary neuronal cultures highlighted the safety profile of hybrid NPs. Moreover, after internalization, NPs are able to transiently destabilize the integrity of lysosomes in which they are taken up, speeding their escape and favoring cytoplasmatic localization. Thus, these DOPE/PLGA-NPs configure themselves as promising carriers for intracellular protein delivery.

  8. Isoflurane reversibly destabilizes hippocampal dendritic spines by an actin-dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Jimcy Platholi

    Full Text Available General anesthetics produce a reversible coma-like state through modulation of excitatory and inhibitory synaptic transmission. Recent evidence suggests that anesthetic exposure can also lead to sustained cognitive dysfunction. However, the subcellular effects of anesthetics on the structure of established synapses are not known. We investigated effects of the widely used volatile anesthetic isoflurane on the structural stability of hippocampal dendritic spines, a postsynaptic structure critical to excitatory synaptic transmission in learning and memory. Exposure to clinical concentrations of isoflurane induced rapid and non-uniform shrinkage and loss of dendritic spines in mature cultured rat hippocampal neurons. Spine shrinkage was associated with a reduction in spine F-actin concentration. Spine loss was prevented by either jasplakinolide or cytochalasin D, drugs that prevent F-actin disassembly. Isoflurane-induced spine shrinkage and loss were reversible upon isoflurane elimination. Thus, isoflurane destabilizes spine F-actin, resulting in changes to dendritic spine morphology and number. These findings support an actin-based mechanism for isoflurane-induced alterations of synaptic structure in the hippocampus. These reversible alterations in dendritic spine structure have important implications for acute anesthetic effects on excitatory synaptic transmission and synaptic stability in the hippocampus, a locus for anesthetic-induced amnesia, and have important implications for anesthetic effects on synaptic plasticity.

  9. Space geodetic monitoring of engineered structures: The ongoing destabilization of the Mosul dam, Iraq.

    Science.gov (United States)

    Milillo, Pietro; Bürgmann, Roland; Lundgren, Paul; Salzer, Jacqueline; Perissin, Daniele; Fielding, Eric; Biondi, Filippo; Milillo, Giovanni

    2016-12-06

    We present a detailed survey of the ongoing destabilization process of the Mosul dam. The dam is located on the Tigris river and is the biggest hydraulic structure in Iraq. From a geological point of view the dam foundation is poor due to a site geology formed by alternating strata of highly soluble materials including gypsum, anhydrite, marl and limestone. Here we present the first multi-sensor cumulative deformation map for the dam generated from space-based interferometric synthetic aperture radar measurements from the Italian constellation COSMO-SkyMed and the European sensor Sentinel-1a over the period 2014-2016 that we compare to an older dataset spanning 2004-2010 acquired with the European Envisat satellite. We found that deformation was rapid during 2004-2010, slowed in 2012-2014 and increased since August 2014 when grouting operations stopped due to the temporary capture of the dam by the self proclaimed Islamic State. We model the inferred deformation using a Markov chain Monte Carlo approach to solve for change in volume for simple tensile dislocations. Results from recent and historical geodetic datasets suggests that the volume dissolution rate remains constant when the equivalent volume of total concrete injected during re-grouting operations is included in the calculations.

  10. EDTA-induced membrane fluidization and destabilization: biophysical studies on artificial lipid membranes.

    Science.gov (United States)

    Prachayasittikul, Virapong; Isarankura-Na-Ayudhya, Chartchalerm; Tantimongcolwat, Tanawut; Nantasenamat, Chanin; Galla, Hans-Joachim

    2007-11-01

    The molecular mechanism of ethylenediaminetetraacetic acid (EDTA)-induced membrane destabilization has been studied using a combination of four biophysical techniques on artificial lipid membranes. Data from Langmuir film balance and epifluorescence microscopy revealed the fluidization and expansion effect of EDTA on phase behavior of monolayers of either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or mixtures of DPPC and metal-chelating lipids, such as N(alpha),N(alpha)-Bis[carboxymethyl]-N(epsilon)-[(dioctadecylamino)succinyl]-L-lysine or 1,2-dioleoyl-sn-glycero-3-[N-(5-amino-1-carboxypentyl iminodiacetic acid) succinyl]. A plausible explanation could be drawn from the electrostatic interaction between negatively charged groups of EDTA and the positively charged choline head group of DPPC. Intercalation of EDTA into the lipid membrane induced membrane curvature as elucidated by atomic force microscopy. Growth in size and shape of the membrane protrusion was found to be time-dependent upon exposure to EDTA. Further loss of material from the lipid membrane surface was monitored in real time using a quartz crystal microbalance. This indicates membrane restabilization by exclusion of the protrusions from the surface. Loss of lipid components facilitates membrane instability, leading to membrane permeabilization and lysis.

  11. Substrate phosphorylation and feedback regulation in JFK-promoted p53 destabilization.

    Science.gov (United States)

    Sun, Luyang; Shi, Lei; Wang, Feng; Huangyang, Peiwei; Si, Wenzhe; Yang, Jie; Yao, Zhi; Shang, Yongfeng

    2011-02-11

    The p53 tumor suppressor plays a central role in integrating cellular responses to various stresses. Tight regulation of p53 is thus essential for the maintenance of genome integrity and normal cell proliferation. Previously, we reported that JFK, the only Kelch domain-containing F-box protein in human, promotes ubiquitination and degradation of p53 and that unlike the other E3 ligases for p53, all of which possess an intrinsic ubiquitin ligase activity, JFK destabilizes p53 through the assembly of a Skp1-Cul1-F-box complex. Here, we report that the substrate recognition by JFK requires phosphorylation of p53 in its central core region by CSN (COP9 signalosome)-associated kinase. Significantly, inhibition of CSN-associated kinase activity or knockdown of CSN5 impairs JFK-promoted p53 degradation, enhances p53-dependent transcription, and promotes cell growth suppression, G(1) arrest, and apoptosis. Moreover, we showed that JFK is transcriptionally regulated by p53 and forms an auto-regulatory negative feedback loop with p53. These data may shed new light on the functional connection between CSN, Skp1-Cul1-F-box ubiquitin ligase, and p53 and provide a molecular mechanism for the regulation of JFK-promoted p53 degradation.

  12. The destabilization of the French electricity supply industry nascent competition in an open environment

    Energy Technology Data Exchange (ETDEWEB)

    Finon, D

    2001-06-01

    In February 2000 France, compelled by the 1996 European Directive 96/92, undertook a minimal reform of the organisation of its electricity industry, while preserving the boundaries of the incumbent company. The aim of this paper is to analyse the conditions of destabilization of the industrial organisation of the French ESI, by identifying the economic factors of endogenous and exogenous erosion. Firstly, after setting out the main elements of the French reform, which is aimed at making the electricity market contestable, the effectiveness of the ''contestability'' of the French power market is discussed. Secondly in order to test the stability of the new institutional arrangements, an institutional prospect is developed, on the basis of economic factors of instability and resistance, to produce two contrasting scenarios: one in which the particularly French model is retained (limited contestability market scenario); another in which there is movement towards a de-integrated competitive model (contamination by competition scenario). Thirdly the author concludes on the basis of recent elements, that the future would be a mix of these two trajectories which will come within in the progressive integration of the national markets in continental Europe. (A.L.B.)

  13. Destabilization of long-wavelength Love and Stoneley waves in slow sliding

    CERN Document Server

    Ranjith, K

    2008-01-01

    Love waves are dispersive interfacial waves that are a mode of response for anti-plane motions of an elastic layer bonded to an elastic half-space. Similarly, Stoneley waves are interfacial waves in bonded contact of dissimilar elastic half-spaces, when the displacements are in the plane of the solids. It is shown that in slow sliding, long wavelength Love and Stoneley waves are destabilized by friction. Friction is assumed to have a positive instantaneous logarithmic dependence on slip rate and a logarithmic rate weakening behavior at steady-state. Long wavelength instabilities occur generically in sliding with rate- and state-dependent friction, even when an interfacial wave does not exist. For slip at low rates, such instabilities are quasi-static in nature, i.e., the phase velocity is negligibly small in comparison to a shear wave speed. The existence of an interfacial wave in bonded contact permits an instability to propagate with a speed of the order of a shear wave speed even in slow sliding, indicatin...

  14. PROTEASES AND PROTEASE INHIBITORS INTERACTION: DEFENCE STRATEGY AGAINST

    Directory of Open Access Journals (Sweden)

    R.S.DHANDE 1 N.J.CHIKHALE 2

    2014-12-01

    Full Text Available ABSTRACT: An increase in crop yield, its management and preservation are among the main challenges standing before the human population that exceed 10 billion by the mid of 21 st  century.  Every year, considerable agricultural losses occur due to repeated practices of cultivation of large genetically similar populations.  Such cultivation practices favors incidence of more insect pests (Hilder and Boulter, 1999;  Oerke  et  al.,  1994;  Smith,  1999.  To  solve  these  problems,  current approaches  rely  on  use  of  synthetic  chemicals  like  fertilizers,  insecticides, herbicides,  fungicides  etc.  But  this  exerts  excessively  high  pressure  on environment  and  destabilizes  the  ecological  balance.  The  traditional  pest control method involves the use of conventional pesticides, most of which are non-specific and wipe out the entire community, pollutes the agro-ecosystem, and  increases  the  cost  of  production.  The  emergence  of  gene  transfer technology  has  solved  some  problems  regarding  overuse  of  chemical pesticides.  The  delta  endotoxin  encoding  gene  from  Bacillus  thuringiensis,  a gram positive soil borne bacteria transferred in crops has given little relief from coleopterans and lepidopterans attack.  Whereas, the insects belonging to these orders like Helicoverpa Sps. have developed resistance against Bt toxins. The other approach takes advantage of use of plant genes encoding defense proteins like protease inhibitors which is more appealing, simpler and safer (Dunaevsky et.  al.,  2005.  Proteinase  inhibitors  (PIs  are  naturally  occurring  proteins  in living organisms and are able to inhibit & control the activity of proteases. PIs act  on  an  active  site  of  digestive  proteolytic  enzymes  and  form  a  stable complex  unlike  enzyme-substrate  or  enzyme-product  weak  complexes  which

  15. Does sex-selective predation stabilize or destabilize predator-prey dynamics?

    Directory of Open Access Journals (Sweden)

    David S Boukal

    Full Text Available BACKGROUND: Little is known about the impact of prey sexual dimorphism on predator-prey dynamics and the impact of sex-selective harvesting and trophy hunting on long-term stability of exploited populations. METHODOLOGY AND PRINCIPAL FINDINGS: We review the quantitative evidence for sex-selective predation and study its long-term consequences using several simple predator-prey models. These models can be also interpreted in terms of feedback between harvesting effort and population size of the harvested species under open-access exploitation. Among the 81 predator-prey pairs found in the literature, male bias in predation is 2.3 times as common as female bias. We show that long-term effects of sex-selective predation depend on the interplay of predation bias and prey mating system. Predation on the 'less limiting' prey sex can yield a stable predator-prey equilibrium, while predation on the other sex usually destabilizes the dynamics and promotes population collapses. For prey mating systems that we consider, males are less limiting except for polyandry and polyandrogyny, and male-biased predation alone on such prey can stabilize otherwise unstable dynamics. On the contrary, our results suggest that female-biased predation on polygynous, polygynandrous or monogamous prey requires other stabilizing mechanisms to persist. CONCLUSIONS AND SIGNIFICANCE: Our modelling results suggest that the observed skew towards male-biased predation might reflect, in addition to sexual selection, the evolutionary history of predator-prey interactions. More focus on these phenomena can yield additional and interesting insights as to which mechanisms maintain the persistence of predator-prey pairs over ecological and evolutionary timescales. Our results can also have implications for long-term sustainability of harvesting and trophy hunting of sexually dimorphic species.

  16. The developmental outcomes of P0-mediated ARGONAUTE destabilization in tomato.

    Science.gov (United States)

    Hendelman, Anat; Kravchik, Michael; Stav, Ran; Zik, Moriyah; Lugassi, Nitsan; Arazi, Tzahi

    2013-01-01

    The plant protein ARGONAUTE1 (AGO1) functions in multiple RNA-silencing pathways, including those of microRNAs, key regulators of growth and development. Genetic analysis of ago1 mutants with informative defects has provided valuable insights into AGO1's biological functions. Tomato encodes two AGO1 homologs (SlAGO1s), but mutants have not been described to date. To analyze SlAGO1s' involvement in development, we confirmed that both undergo decay in the presence of the Polerovirus silencing suppressor P0 and produce a transgenic responder line (OP:P0HA) that, upon transactivation, expresses P0 C-terminally fused to a hemagglutinin (HA) tag (P0HA) and destabilizes SlAGO1s at the site of expression. By crossing OP:P0HA with a battery of driver lines, constitutive as well as organ- and stage-specific SlAGO1 downregulation was induced in the F1 progeny. Activated plants exhibited various developmental phenotypes that partially overlapped with those of Arabidopsis ago1 mutants. Plants that constitutively expressed P0HA had reduced SlAGO1 levels and increased accumulation of miRNA targets, indicating compromised SlAGO1-mediated silencing. Consistent with this, they exhibited pleiotropic morphological defects and their growth was arrested post-germination. Transactivation of P0HA in young leaf and floral organ primordia dramatically modified corresponding organ morphology, including the radialization of leaflets, petals and anthers, suggesting that SlAGO1s' activities are required for normal lateral organ development and polarity. Overall, our results suggest that the OP:P0HA responder line can serve as a valuable tool to suppress SlAGO1 silencing pathways in tomato. The suppression of additional SlAGOs by P0HA and its contribution to the observed phenotypes awaits investigation.

  17. An Archaean heavy bombardment from a destabilized extension of the asteroid belt.

    Science.gov (United States)

    Bottke, William F; Vokrouhlický, David; Minton, David; Nesvorný, David; Morbidelli, Alessandro; Brasser, Ramon; Simonson, Bruce; Levison, Harold F

    2012-05-03

    The barrage of comets and asteroids that produced many young lunar basins (craters over 300 kilometres in diameter) has frequently been called the Late Heavy Bombardment (LHB). Many assume the LHB ended about 3.7 to 3.8 billion years (Gyr) ago with the formation of Orientale basin. Evidence for LHB-sized blasts on Earth, however, extend into the Archaean and early Proterozoic eons, in the form of impact spherule beds: globally distributed ejecta layers created by Chicxulub-sized or larger cratering events4. At least seven spherule beds have been found that formed between 3.23 and 3.47 Gyr ago, four between 2.49 and 2.63 Gyr ago, and one between 1.7 and 2.1 Gyr ago. Here we report that the LHB lasted much longer than previously thought, with most late impactors coming from the E belt, an extended and now largely extinct portion of the asteroid belt between 1.7 and 2.1 astronomical units from Earth. This region was destabilized by late giant planet migration. E-belt survivors now make up the high-inclination Hungaria asteroids. Scaling from the observed Hungaria asteroids, we find that E-belt projectiles made about ten lunar basins between 3.7 and 4.1 Gyr ago. They also produced about 15 terrestrial basins between 2.5 and 3.7 Gyr ago, as well as around 70 and four Chicxulub-sized or larger craters on the Earth and Moon, respectively, between 1.7 and 3.7 Gyr ago. These rates reproduce impact spherule bed and lunar crater constraints.

  18. Enhanced North Atlantic deep convection preceding Heinrich 1 glacial ice sheet destabilization

    Science.gov (United States)

    Seidenkrantz, Marit-Solveig; Kuijpers, Antoon; Lindgreen, Holger

    2015-04-01

    The Labrador Sea is a crucial center of action for North Atlantic meridional overturning circulation. This region is characterized in winter by strong cold and dry winds from land or ice surfaces inducing large heat and moisture fluxes at the ocean-atmosphere interface. Particularly in late winter these conditions favor deep-convection processes leading to the formation of a relatively homogeneous and oxygen-rich intermediate water mass (Labrador Sea Water, LSW) spreading to other parts of the North Atlantic at water depths between about 1,000 and 2,000 m. Sedimentary records from the Labrador Sea have previously indicated here the presence of North Atlantic Deep Water during periods in between glacial ('Heinrich') ice-rafting events. The present sediment core investigation based on clay mineralogical analysis and study of the benthic foraminiferal fauna shows a significant oxygenation event at 18000 cal.yrs BP recorded both in the Labrador Sea and at the northern margin of Rockall Trough at 2381 m and 1286 m water depth, respectively. We conclude this ventilation pulse to be related to a period of enhanced deep convection and formation of glacial North Atlantic Intermediate Water occupying those parts of the water column presently affected under conditions of strong LSW formation. This ventilation event implies an early, significant re-activation of North Atlantic meridional overturning circulation after the Last Glacial Maximum immediately prior to Heinrich 1 large-scale ice-sheet destabilization. This scenario points to an oceanic trigger mechanism for large-scale glacial iceberg surges around the northern North Atlantic, which involves enhanced northward ocean (sub)surface heat transport and subsequent enhanced bottom melting of floating outlet glaciers and ice shelves.

  19. Morphology and Mechanism of Benign Inhibitors

    Science.gov (United States)

    2012-07-01

    the water response of vanadate inhibitor films can be determined. Because the absorbed water usually resides in molecular-level free space inside...Schaefer, Water absorption and transport in bis- silane films. Physical Chemistry Chemical Physics, 2009. 11(1), p. 161 - 166. 23. Y. Wang, E. Watkins, J...Ooij, Effects of addition of corrosion inhibitors to silane films on the performance of AA2024-T3 in a 0.5M NaCl solution. Progress in Organic

  20. Chemical Inhibition of Autophagy

    DEFF Research Database (Denmark)

    Baek, Eric; Lin Kim, Che; Gyeom Kim, Mi;

    2016-01-01

    Chinese hamster ovary (CHO) cells activate and undergo apoptosis and autophagy for various environmental stresses. Unlike apoptosis, studies on increasing the production of therapeutic proteins in CHO cells by targeting the autophagy pathway are limited. In order to identify the effects of chemical...... autophagy inhibitors on the specific productivity (qp), nine chemical inhibitors that had been reported to target three different phases of autophagy (metformin, dorsomorphin, resveratrol, and SP600125 against initiation and nucleation; 3-MA, wortmannin, and LY294002 against elongation, and chloroquine...... and bafilomycin A1 against autophagosome fusion) were used to treat three recombinant CHO (rCHO) cell lines: the Fc-fusion protein-producing DG44 (DG44-Fc) and DUKX-B11 (DUKX-Fc) and antibody-producing DG44 (DG44-Ab) cell lines. Among the nine chemical inhibitors tested, 3-MA, dorsomorphin, and SP600125...

  1. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    Directory of Open Access Journals (Sweden)

    Meehan Maria

    2012-02-01

    Full Text Available Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA, an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA's primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  2. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    LENUS (Irish Health Repository)

    Meehan, Maria

    2012-02-05

    Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD) is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA), an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA\\'s primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  3. Poliovirus-associated protein kinase: Destabilization of the virus capsid and stimulation of the phosphorylation reaction by Zn sup 2+

    Energy Technology Data Exchange (ETDEWEB)

    Ratka, M.; Lackmann, M.; Ueckermann, C.; Karlins, U.; Koch, G. (Univ. of Hamburg (West Germany))

    1989-09-01

    The previously described poliovirus-associated protein kinase activity phosphorylates viral proteins VP0 and VP2 as well as exogenous proteins in the presence of Mg{sup 2+}. In this paper, the effect of Zn{sup 2+} on the phosphorylation reaction and the stability of the poliovirus capsid has been studied in detail and compared to that of Mg{sup 2+}. In the presence of Zn{sup 2+}, phosphorylation of capsid proteins VP2 and VP4 is significantly higher while phosphorylation of VP0 and exogenous phosphate acceptor proteins is not detected. The results indicate the activation of more than one virus-associated protein kinase by Zn{sup 2+}. The ion-dependent behavior of the enzyme activities is observed independently of whether the virus was obtained from HeLa or green monkey kidney cells. The poliovirus capsid is destabilized by Zn{sup 2+}. This alteration of the poliovirus capsid structure is a prerequisite for effective phosphorylation of viral capsid proteins. The increased level of phosphorylation of viral capsid proteins results in further destabilization of the viral capsid. As a result of the conformational changes, poliovirus-associated protein kinase activities dissociate from the virus particle. The authors suggest that the destabilizing effect of phosphorylation on the viral capsid plays a role in uncoating of poliovirus.

  4. Alpha-helical destabilization of the Bcl-2-BH4-domain peptide abolishes its ability to inhibit the IP3 receptor.

    Directory of Open Access Journals (Sweden)

    Giovanni Monaco

    Full Text Available The anti-apoptotic Bcl-2 protein is the founding member and namesake of the Bcl-2-protein family. It has recently been demonstrated that Bcl-2, apart from its anti-apoptotic role at mitochondrial membranes, can also directly interact with the inositol 1,4,5-trisphosphate receptor (IP3R, the primary Ca(2+-release channel in the endoplasmic reticulum (ER. Bcl-2 can thereby reduce pro-apoptotic IP3R-mediated Ca(2+ release from the ER. Moreover, the Bcl-2 homology domain 4 (Bcl-2-BH4 has been identified as essential and sufficient for this IP3R-mediated anti-apoptotic activity. In the present study, we investigated whether the reported inhibitory effect of a Bcl-2-BH4 peptide on the IP 3R1 was related to the distinctive α-helical conformation of the BH4 domain peptide. We therefore designed a peptide with two glycine "hinges" replacing residues I14 and V15, of the wild-type Bcl-2-BH4 domain (Bcl-2-BH4-IV/GG. By comparing the structural and functional properties of the Bcl-2-BH4-IV/GG peptide with its native counterpart, we found that the variant contained reduced α-helicity, neither bound nor inhibited the IP 3R1 channel, and in turn lost its anti-apoptotic effect. Similar results were obtained with other substitutions in Bcl-2-BH4 that destabilized the α-helix with concomitant loss of IP3R inhibition. These results provide new insights for the further development of Bcl-2-BH4-derived peptides as specific inhibitors of the IP3R with significant pharmacological implications.

  5. Application of Fragment-Based NMR Screening, X-ray Crystallography, Structure-Based Design, and Focused Chemical Library Design to Identify Novel [mu]M Leads for the Development of nM BACE-1 ([beta]-Site APP Cleaving Enzyme 1) Inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu-Sen; Strickland, Corey; Voigt, Johannes H.; Kennedy, Matthew E.; Beyer, Brian M.; Senior, Mary M.; Smith, Elizabeth M.; Nechuta, Terry L.; Madison, Vincent S.; Czarniecki, Michael; McKittrick, Brian A.; Stamford, Andrew W.; Parker, Eric M.; Hunter, John C.; Greenlee, William J.; Wyss, Daniel F. (SPRI)

    2010-10-18

    Fragment-based NMR screening, X-ray crystallography, structure-based design, and focused chemical library design were used to identify novel inhibitors for BACE-1. A rapid optimization of an initial NMR hit was achieved by a combination of NMR and a functional assay, resulting in the identification of an isothiourea hit with a K{sub d} of 15 {micro}M for BACE-1. NMR data and the crystal structure revealed that this hit makes H-bond interactions with the two catalytic aspartates, occupies the nonprime side region of the active site of BACE-1, and extends toward the S3 subpocket (S3sp). A focused NMR-based search for heterocyclic isothiourea isosteres resulted in several distinct classes of BACE-1 active site directed compounds with improved chemical stability and physicochemical properties. The strategy for optimization of the 2-aminopyridine lead series to potent inhibitors of BACE-1 was demonstrated. The structure-based design of a cyclic acylguanidine lead series and its optimization into nanomolar BACE-1 inhibitors are the subject of the companion paper (J. Med. Chem. 2010, 53, DOI:10.1021/jm901408p).

  6. L-arginine destabilizes oral multi-species biofilm communities developed in human saliva.

    Science.gov (United States)

    Kolderman, Ethan; Bettampadi, Deepti; Samarian, Derek; Dowd, Scot E; Foxman, Betsy; Jakubovics, Nicholas S; Rickard, Alexander H

    2015-01-01

    The amino acid L-arginine inhibits bacterial coaggregation, is involved in cell-cell signaling, and alters bacterial metabolism in a broad range of species present in the human oral cavity. Given the range of effects of L-arginine on bacteria, we hypothesized that L-arginine might alter multi-species oral biofilm development and cause developed multi-species biofilms to disassemble. Because of these potential biofilm-destabilizing effects, we also hypothesized that L-arginine might enhance the efficacy of antimicrobials that normally cannot rapidly penetrate biofilms. A static microplate biofilm system and a controlled-flow microfluidic system were used to develop multi-species oral biofilms derived from pooled unfiltered cell-containing saliva (CCS) in pooled filter-sterilized cell-free saliva (CFS) at 37° C. The addition of pH neutral L-arginine monohydrochloride (LAHCl) to CFS was found to exert negligible antimicrobial effects but significantly altered biofilm architecture in a concentration-dependent manner. Under controlled flow, the biovolume of biofilms (μm(3)/μm(2)) developed in saliva containing 100-500 mM LAHCl were up to two orders of magnitude less than when developed without LAHCI. Culture-independent community analysis demonstrated that 500 mM LAHCl substantially altered biofilm species composition: the proportion of Streptococcus and Veillonella species increased and the proportion of Gram-negative bacteria such as Neisseria and Aggregatibacter species was reduced. Adding LAHCl to pre-formed biofilms also reduced biovolume, presumably by altering cell-cell interactions and causing cell detachment. Furthermore, supplementing 0.01% cetylpyridinium chloride (CPC), an antimicrobial commonly used for the treatment of dental plaque, with 500 mM LAHCl resulted in greater penetration of CPC into the biofilms and significantly greater killing compared to a non-supplemented 0.01% CPC solution. Collectively, this work demonstrates that LAHCl moderates multi

  7. Salt bridges destabilize a leucine zipper designed for maximized ion pairing between helices.

    Science.gov (United States)

    Phelan, Paul; Gorfe, Alemayehu A; Jelesarov, Ilian; Marti, Daniel N; Warwicker, James; Bosshard, Hans Rudolf

    2002-03-05

    Interhelical salt bridges are common in leucine zippers and are thought to stabilize the coiled coil conformation. Here we present a detailed thermodynamic investigation of the designed, disulfide-linked leucine zipper AB(SS) whose high-resolution NMR structure shows six interhelical ion pairs between heptad positions g of one helix and e' of the other helix but no ion pairing within single helices. The average pK(a) value of the Glu side chain carboxyl groups of AB(SS) is slightly higher than the pK(a) of a freely accessible Glu in an unfolded peptide [Marti, D. N., Jelesarov, I., and Bosshard, H. R. (2000) Biochemistry 39, 12804-12818]. This indicates that the salt bridges are destabilizing, a prediction we now have confirmed by determining the pH +/- stability profile of AB(SS). Circular dichroism-monitored unfolding by urea and by heating and differential scanning calorimetry show that the coiled coil conformation is approximately 5 kJ/mol more stable when salt bridges are broken by protonation of the carboxyl side chains. Using guanidinium chloride as the denaturant, the increase in the free energy of unfolding on protonation of the carboxyl side chains is larger, approximately 17 kJ/mol. The discrepancy between urea and guanidinium chloride unfolding can be ascribed to the ionic nature of guanidinium chloride, which screens charge-charge interactions. This work demonstrates the difficulty of predicting the energetic contribution of salt bridges from structural data alone even in a case where the ion pairs are seen in high-resolution NMR structures. The reason is that the contribution to stability results from a fine balance between energetically favorable Coulombic attractions and unfavorable desolvation of charges and conformational constraints of the residues involved in ion pairing. The apparent discrepancy between the results presented here and mutational studies indicating stabilization by salt bridges is discussed and resolved. An explanation is

  8. L-arginine destabilizes oral multi-species biofilm communities developed in human saliva.

    Directory of Open Access Journals (Sweden)

    Ethan Kolderman

    Full Text Available The amino acid L-arginine inhibits bacterial coaggregation, is involved in cell-cell signaling, and alters bacterial metabolism in a broad range of species present in the human oral cavity. Given the range of effects of L-arginine on bacteria, we hypothesized that L-arginine might alter multi-species oral biofilm development and cause developed multi-species biofilms to disassemble. Because of these potential biofilm-destabilizing effects, we also hypothesized that L-arginine might enhance the efficacy of antimicrobials that normally cannot rapidly penetrate biofilms. A static microplate biofilm system and a controlled-flow microfluidic system were used to develop multi-species oral biofilms derived from pooled unfiltered cell-containing saliva (CCS in pooled filter-sterilized cell-free saliva (CFS at 37° C. The addition of pH neutral L-arginine monohydrochloride (LAHCl to CFS was found to exert negligible antimicrobial effects but significantly altered biofilm architecture in a concentration-dependent manner. Under controlled flow, the biovolume of biofilms (μm(3/μm(2 developed in saliva containing 100-500 mM LAHCl were up to two orders of magnitude less than when developed without LAHCI. Culture-independent community analysis demonstrated that 500 mM LAHCl substantially altered biofilm species composition: the proportion of Streptococcus and Veillonella species increased and the proportion of Gram-negative bacteria such as Neisseria and Aggregatibacter species was reduced. Adding LAHCl to pre-formed biofilms also reduced biovolume, presumably by altering cell-cell interactions and causing cell detachment. Furthermore, supplementing 0.01% cetylpyridinium chloride (CPC, an antimicrobial commonly used for the treatment of dental plaque, with 500 mM LAHCl resulted in greater penetration of CPC into the biofilms and significantly greater killing compared to a non-supplemented 0.01% CPC solution. Collectively, this work demonstrates that LAHCl

  9. HER2 phosphorylates and destabilizes pro-apoptotic PUMA, leading to antagonized apoptosis in cancer cells.

    Science.gov (United States)

    Carpenter, Richard L; Han, Woody; Paw, Ivy; Lo, Hui-Wen

    2013-01-01

    HER2 is overexpressed in 15-20% of breast cancers. HER2 overexpression is known to reduce apoptosis but the underlying mechanisms for this association remain unclear. To elucidate the mechanisms for HER2-mediated survival, we investigated the relationship between HER2 and p53 upregulated modulator of apoptosis (PUMA), a potent apoptosis inducer. Our results showed that HER2 interacts with PUMA, which was independent of HER2 activation. In addition, we observed that HER2 interacted with PUMA in both mitochondrial and non-mitochondrial compartments. We next examined whether HER2 phosphorylates PUMA. Notably, PUMA tyrosine phosphorylation has never been reported. Using an intracellular assay, we found PUMA to be phosphorylated in breast cancer cells with activated HER2. Via cell-free HER2 kinase assay, we observed that PUMA was directly phosphorylated by HER2. Activation of HER2 decreased PUMA protein half-life. To identify which of the three tyrosines within PUMA are targeted by HER2, we generated three PUMA non-phosphorylation mutants each with a single Tyr→Phe substitution. Results indicated that each PUMA single mutant had lost some, but not all phosphorylation by HER2 indicating that HER2 targets all three tyrosines. Consequently, we created an additional PUMA mutant with all three tyrosines mutated (TM-PUMA) that could not be phosphorylated by HER2. Importantly, TM-PUMA was found to have a longer half-life than PUMA. An inverse association was observed between HER2 and PUMA in 93 invasive breast carcinoma samples. We further found that TM-PUMA suppressed growth of breast cancer cells to a greater degree than PUMA. Also, TM-PUMA had a stronger propensity to induce apoptosis than PUMA. Together, our results demonstrate, for the first time, that PUMA can be tyrosine phosphorylated and that HER2-mediated phosphorylation destabilizes PUMA protein. The HER2-PUMA interplay represents a novel mechanism by which PUMA is regulated and a new molecular basis for HER2

  10. Proton pump inhibitors

    Science.gov (United States)

    Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This ...

  11. A new class of ghrelin O-acyltransferase inhibitors incorporating triazole-linked lipid mimetic groups.

    Science.gov (United States)

    Zhao, Feifei; Darling, Joseph E; Gibbs, Richard A; Hougland, James L

    2015-07-15

    Inhibitors of ghrelin O-acyltransferase (GOAT) have untapped potential as therapeutics targeting obesity and diabetes. We report the first examples of GOAT inhibitors incorporating a triazole linkage as a biostable isosteric replacement for the ester bond in ghrelin and amide bonds in previously reported GOAT inhibitors. These triazole-containing inhibitors exhibit sub-micromolar inhibition of the human isoform of GOAT (hGOAT), and provide a foundation for rapid future chemical diversification and optimization of hGOAT inhibitors.

  12. Early vessel destabilization mediated by Angiopoietin-2 and subsequent vessel maturation via Angiopoietin-1 induce functional neovasculature after ischemia.

    Directory of Open Access Journals (Sweden)

    Di Qin

    Full Text Available BACKGROUND: We assessed whether Angiopoietin-2 (Ang2, a Tie2 ligand and partial antagonist of Angiopoietin-1 (Ang1, is required for early vessel destabilization during postischemic angiogenesis, when combined with vascular growth factors. METHODS: In vitro, matrigel co-cultures assessed endothelial-cell tube formation and pericyte recruitment after stimulation of VEGF-A, Apelin (APLN, Ang1 with or without Ang2. In a murine hindlimb ischemia model, adeno-associated virus (rAAV, 3×10(12 virusparticles transduction of VEGF-A, APLN and Ang1 with or without Ang2 (continuous or early expression d0-3 was performed intramuscularly (d-14. Femoral artery ligation was performed at d0, followed by laser doppler perfusion meassurements (LDI 7 and 14. At d7 (early timepoint and d14 (late timepoint, histological analysis of capillary/muscle fiber ratio (CMF-R, PECAM-1 and pericyte/capillary ratio (PC-R, NG2 was performed. RESULTS: In vitro, VEGF-A, APLN and Ang1 induced ring formation, but only APLN and Ang1 recruited pericytes. Ang2 did not affect tube formation by APLN, but reduced pericyte recruitment after APLN or Ang1 overexpression. In vivo, rAAV.VEGF-A did not alter LDI-perfusion at d14, consistent with an impaired PC-R despite a rise in CMF-R. rAAV.APLN improved perfusion at d14, with or without continuous Ang2, increasing CMF-R and PC-R. rAAV.Ang1 improved perfusion at d14, when combined with rAAV.Ang2 (d0-3, accompanied by an increased CMF-R and PC-R. CONCLUSION: The combination of early vessel destabilization (Ang2 d0-3 and continuous Ang1 overexpression improves hindlimb perfusion, pointing to the importance of early vessel destabilization and subsequent vessel maturation for enhanced therapeutic neovascularization.

  13. Nitrogen heterocycles as potential monoamine oxidase inhibitors: Synthetic aspects

    Directory of Open Access Journals (Sweden)

    Pravin O. Patil

    2014-12-01

    Full Text Available The present review highlights the synthetic methods of monoamine oxidase inhibitors (MAO belonging to a group of nitrogen heterocycles such as pyrazoline, indole, xanthine, oxadiazole, benzimidazole, pyrrole, quinoxaline, thiazole and other related compounds (1990–2012. Moreover, it emphasizes salient findings related to chemical structures and the bioactivities of these heterocycles as MAO inhibitors. The aim of this review is to find out different methods for the synthesis of nitrogen containing heterocycles and their bioactivity related aspects as MAO inhibitors.

  14. Destabilization of survival factor MEF2D mRNA by neurotoxin in models of Parkinson's disease.

    Science.gov (United States)

    Wang, Bao; Cai, Zhibiao; Lu, Fangfang; Li, Chen; Zhu, Xiaofei; Su, Linna; Gao, Guodong; Yang, Qian

    2014-09-01

    Progressive loss of dopaminergic (DA) neurons in the substantial nigra pars compacta (SNc) is an important pathological feature in Parkinson's disease (PD). Loss of transcription factor myocyte enhancer factor 2D (MEF2D), a key neuronal survival factor, has been shown to underlie the loss of DA neurons in SNc and the pathogenic process of PD. It is known that PD-associated neurotoxins reduce the level of MEF2D protein to trigger neuronal death. Although neurotoxins clearly destabilize MEF2D by post-translational mechanisms, it is not known whether regulation of MEF2D mRNA contributes to neurotoxin-induced decrease in MEF2D protein. In this work, we showed that MPP(+), the toxic metabolite of MPTP, caused a significant decrease in the half-life and total level of MEF2D mRNA in a DA neuronal cell line, SN4741 cells. Quantitative PCR analysis of the SNc DA neurons captured by immune-laser capture microdissection showed that exposure to MPTP led to a marked reduction in the level of MEF2D mRNA in SNc DA neurons compared to controls. Down-regulation of MEF2D mRNA alone reduced the viability of SN4741 cells and sensitized the cells to MPP(+)-induced toxicity. These results suggest that destabilization and reduction in MEF2D mRNA is in part responsible for neurotoxin-induced decrease in MEF2D protein and neuronal viability. Myocyte enhancer factor 2D (MEF2D) plays an important role in neuronal survival. How MEF2D mRNA is deregulated under toxic stress is unclear. We found that PD-associated neurotoxins destabilize MEF2D mRNA and reduce its level in vitro and in vivo. Reduction in MEF2D mRNA is sufficient to sensitize model cells to neurotoxin-induced toxicity, suggesting that destabilization of MEF2D mRNA is part of the mechanism by which neurotoxins trigger deregulation of neuronal survival.

  15. Warm, salty surface water incursions and destabilization of the Cordilleran Ice Sheet

    Science.gov (United States)

    Taylor, M.; Hendy, I. L.; Pak, D. K.

    2012-12-01

    Ocean temperature change has the potential to destabilize tide-water glaciers and ice shelves. Here we investigate the potential impact of changing North Pacific sea surface temperatures (SST) on the stability of the Cordilleran Ice Sheet during the last deglaciation. Stable isotope values and trace metal ratios were generated on the planktonic foraminifera Neogloboquadrina pachyderma and Globigerina bulloides from core MD02-2496, (1243 m water depth; 48°58N, 127°02W), British Columbia. The site is located where the North Pacific Current bifurcates in the modern climate system, transporting water northward into the Alaskan Gyre and southward to the California Current system. In addition as the site is ~35 km from the coast of Vancouver Island, it is ideally located to detect changes in Cordilleran Ice Sheet behavior. The region is also affected by plumes from the Columbia River deflected north by the Coriolis effect, making it possible to monitor Glacial Lake Missoula Outburst Flooding. The high-resolution (50-200cm kyr-1) reconstruction of SST and δ18Oseawater (salinity) reveals cool (4-7°C), relatively fresh and stratified surface waters occupied the region between 20 and 16.5 ka. Frequent incursions of warm (>10°C), relatively saline water on decadal to centennial timescales began ~18.8 kyr, persisting until ~14.7 kyr. Reconstructed warm and salty waters from 18.5-17.9 kyr are associated with cyclic (~80 year) sedimentation of terrigenous organic carbon-rich, >300 Ma shale-like sediments, which may be evidence of Lake Missoula outburst floodwaters. These sediments contrast with the typical ~100 Ma volcanic sediments typically deposited during deglaciation. A step-wise warming of ~2-4°C occurs at ~16.6 ka and both planktonic foraminiferal species record identical SSTs until ~14.7 ka. During this interval the Vancouver Margin surface waters were relatively more saline and very well mixed. The warmest (14.5-16°C) incursion of saline water occurs at ~16.5 ka

  16. Dendrimers destabilize proteins in a generation-dependent manner involving electrostatic interactions

    DEFF Research Database (Denmark)

    Gichm, Lise; Christensen, Casper; Boas, Ulrik

    2008-01-01

    Dendrimers are well-defined chemical polymers with a characteristic branching pattern that gives rise to attractive features such as antibacterial and antitumor activities as well as drug delivery properties. In addition, dendrimers can solubilize prion protein aggregates at very low concentratio...

  17. Pironetin reacts covalently with cysteine-316 of α-tubulin to destabilize microtubule

    Science.gov (United States)

    Yang, Jianhong; Wang, Yuxi; Wang, Taijing; Jiang, Jian; Botting, Catherine H.; Liu, Huanting; Chen, Qiang; Yang, Jinliang; Naismith, James H.; Zhu, Xiaofeng; Chen, Lijuan

    2016-06-01

    Molecules that alter the normal dynamics of microtubule assembly and disassembly include many anticancer drugs in clinical use. So far all such therapeutics target β-tubulin, and structural biology has explained the basis of their action and permitted design of new drugs. However, by shifting the profile of β-tubulin isoforms, cancer cells become resistant to treatment. Compounds that bind to α-tubulin are less well characterized and unexploited. The natural product pironetin is known to bind to α-tubulin and is a potent inhibitor of microtubule polymerization. Previous reports had identified that pironetin reacts with lysine-352 residue however analogues designed on this model had much lower potency, which was difficult to explain, hindering further development. We report crystallographic and mass spectrometric data that reveal that pironetin forms a covalent bond to cysteine-316 in α-tubulin via a Michael addition reaction. These data provide a basis for the rational design of α-tubulin targeting chemotherapeutics.

  18. Effects of the lysosomal destabilizing drug siramesine on glioblastoma in vitro and in vivo

    DEFF Research Database (Denmark)

    Jensen, Stine S.; Asferg Petterson, Stine; Halle, Bo

    2017-01-01

    - and chemoresistant brain tumor-initiating cells combined with the invasive properties of the tumors is believed to be critical for treatment resistance. In the present study, the aim was to investigate the effect of a novel therapeutic strategy using the lysosomotropic detergent siramesine on glioblastomas. Methods......Background: Glioblastoma is the most frequent and most malignant brain tumor with the patients having a median survival of only 14.6 months. Although glioblastoma patients are treated with surgery, radiation and chemotherapy recurrence is inevitable. A stem-like population of radio......: Standard glioma cell lines and patient-derived spheroids cultures with tumor-initiating stem-like cells were used to investigate effects of siramesine on proliferation and cell death. Responsible mechanisms were investigated by inhibitors of caspases and cathepsins. Effects of siramesine on migrating tumor...

  19. A cypovirus VP5 displays the RNA chaperone-like activity that destabilizes RNA helices and accelerates strand annealing.

    Science.gov (United States)

    Yang, Jie; Cheng, Zhenyun; Zhang, Songliu; Xiong, Wei; Xia, Hongjie; Qiu, Yang; Wang, Zhaowei; Wu, Feige; Qin, Cheng-Feng; Yin, Lei; Hu, Yuanyang; Zhou, Xi

    2014-02-01

    For double-stranded RNA (dsRNA) viruses in the family Reoviridae, their inner capsids function as the machinery for viral RNA (vRNA) replication. Unlike other multishelled reoviruses, cypovirus has a single-layered capsid, thereby representing a simplified model for studying vRNA replication of reoviruses. VP5 is one of the three major cypovirus capsid proteins and functions as a clamp protein to stabilize cypovirus capsid. Here, we expressed VP5 from type 5 Helicoverpa armigera cypovirus (HaCPV-5) in a eukaryotic system and determined that this VP5 possesses RNA chaperone-like activity, which destabilizes RNA helices and accelerates strand annealing independent of ATP. Our further characterization of VP5 revealed that its helix-destabilizing activity is RNA specific, lacks directionality and could be inhibited by divalent ions, such as Mg(2+), Mn(2+), Ca(2+) or Zn(2+), to varying degrees. Furthermore, we found that HaCPV-5 VP5 facilitates the replication initiation of an alternative polymerase (i.e. reverse transcriptase) through a panhandle-structured RNA template, which mimics the 5'-3' cyclization of cypoviral positive-stranded RNA. Given that the replication of negative-stranded vRNA on the positive-stranded vRNA template necessitates the dissociation of the 5'-3' panhandle, the RNA chaperone activity of VP5 may play a direct role in the initiation of reoviral dsRNA synthesis.

  20. A cellular model of memory reconsolidation involves reactivation-induced destabilization and restabilization at the sensorimotor synapse in Aplysia.

    Science.gov (United States)

    Lee, Sue-Hyun; Kwak, Chuljung; Shim, Jaehoon; Kim, Jung-Eun; Choi, Sun-Lim; Kim, Hyoung F; Jang, Deok-Jin; Lee, Jin-A; Lee, Kyungmin; Lee, Chi-Hoon; Lee, Young-Don; Miniaci, Maria Concetta; Bailey, Craig H; Kandel, Eric R; Kaang, Bong-Kiun

    2012-08-28

    The memory reconsolidation hypothesis suggests that a memory trace becomes labile after retrieval and needs to be reconsolidated before it can be stabilized. However, it is unclear from earlier studies whether the same synapses involved in encoding the memory trace are those that are destabilized and restabilized after the synaptic reactivation that accompanies memory retrieval, or whether new and different synapses are recruited. To address this issue, we studied a simple nonassociative form of memory, long-term sensitization of the gill- and siphon-withdrawal reflex in Aplysia, and its cellular analog, long-term facilitation at the sensory-to-motor neuron synapse. We found that after memory retrieval, behavioral long-term sensitization in Aplysia becomes labile via ubiquitin/proteasome-dependent protein degradation and is reconsolidated by means of de novo protein synthesis. In parallel, we found that on the cellular level, long-term facilitation at the sensory-to-motor neuron synapse that mediates long-term sensitization is also destabilized by protein degradation and is restabilized by protein synthesis after synaptic reactivation, a procedure that parallels memory retrieval or retraining evident on the behavioral level. These results provide direct evidence that the same synapses that store the long-term memory trace encoded by changes in the strength of synaptic connections critical for sensitization are disrupted and reconstructed after signal retrieval.

  1. Dimethyl Sulfoxide Induced Destabilization and Disassembly of Various Structural Variants of Insulin Fibrils Monitored by Vibrational Circular Dichroism.

    Science.gov (United States)

    Zhang, Ge; Babenko, Viktoria; Dzwolak, Wojciech; Keiderling, Timothy A

    2015-12-15

    Dimethyl sulfoxide (DMSO) induced destabilization of insulin fibrils has been previously studied by Fourier transform infrared spectroscopy and interpreted in terms of secondary structural changes. The variation of this process for fibrils with different types of higher-order morphological structures remained unclear. Here, we utilize vibrational circular dichroism (VCD), which has been reported to provide a useful biophysical probe of the supramolecular chirality of amyloid fibrils, to characterize changes in the macroscopic chirality following DMSO-induced disassembly for two types of insulin fibrils formed under different conditions, at different reduced pH values with and without added salt and agitation. We confirm that very high concentrations of DMSO can disaggregate both types of insulin fibrils, which initially maintained a β-sheet conformation and eventually changed their secondary structure to a disordered form. The two types responded to varying concentrations of DMSO, and disaggregation followed different mechanisms. Interconversion of specific insulin fibril morphological types also occurred during the destabilization process as monitored by VCD. With transmission electron microscopy, we were able to correlate the changes in VCD sign patterns to alteration of morphology of the insulin fibrils.

  2. Substituted androstanes as aromatase inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Levina, Inna S [N.D.Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-11-30

    The synthesis and structure-activity relationships of inhibitors of steroid aromatase which catalyses the last stage of a multistep biotransformation of cholesterol into estrogens, viz., aromatisation of C{sub 19}-steroids into C{sub 18}-phenolic steroids, are discussed. Compounds of the androstane series which are structurally related to the natural substrate, viz., androst-4-ene-3,17-dione, are the subjects of consideration. The review encompasses problems of synthesis of various substituted androstanes and their aromatase-inhibiting activities and structural requirements for selective specific aromatase inhibitors based on in vitro and in vivo structure-activity studies of compounds synthesised, their biological properties and the results of clinical trials. Special attention is paid to practical applications of aromatase inhibitors in the treatment of hormone-dependent mammary and ovarian tumours as well as benign prostatic tumours. In writing this report, the author has used all the information currently available in the chemical, biochemical, endocrinological and medicinal literature as well as in patents. The bibliography includes 173 references.

  3. Substituted androstanes as aromatase inhibitors

    Science.gov (United States)

    Levina, Inna S.

    1998-11-01

    The synthesis and structure-activity relationships of inhibitors of steroid aromatase which catalyses the last stage of a multistep biotransformation of cholesterol into estrogens, viz., aromatisation of C19-steroids into C18-phenolic steroids, are discussed. Compounds of the androstane series which are structurally related to the natural substrate, viz., androst-4-ene-3,17-dione, are the subjects of consideration. The review encompasses problems of synthesis of various substituted androstanes and their aromatase-inhibiting activities and structural requirements for selective specific aromatase inhibitors based on in vitro and in vivo structure-activity studies of compounds synthesised, their biological properties and the results of clinical trials. Special attention is paid to practical applications of aromatase inhibitors in the treatment of hormone-dependent mammary and ovarian tumours as well as benign prostatic tumours. In writing this report, the author has used all the information currently available in the chemical, biochemical, endocrinological and medicinal literature as well as in patents. The bibliography includes 173 references.

  4. Site-selective probing of cTAR destabilization highlights the necessary plasticity of the HIV-1 nucleocapsid protein to chaperone the first strand transfer

    Science.gov (United States)

    Godet, Julien; Kenfack, Cyril; Przybilla, Frédéric; Richert, Ludovic; Duportail, Guy; Mély, Yves

    2013-01-01

    The HIV-1 nucleocapsid protein (NCp7) is a nucleic acid chaperone required during reverse transcription. During the first strand transfer, NCp7 is thought to destabilize cTAR, the (−)DNA copy of the TAR RNA hairpin, and subsequently direct the TAR/cTAR annealing through the zipping of their destabilized stem ends. To further characterize the destabilizing activity of NCp7, we locally probe the structure and dynamics of cTAR by steady-state and time resolved fluorescence spectroscopy. NC(11–55), a truncated NCp7 version corresponding to its zinc-finger domain, was found to bind all over the sequence and to preferentially destabilize the penultimate double-stranded segment in the lower part of the cTAR stem. This destabilization is achieved through zinc-finger–dependent binding of NC to the G10 and G50 residues. Sequence comparison further revealed that C•A mismatches close to the two G residues were critical for fine tuning the stability of the lower part of the cTAR stem and conferring to G10 and G50 the appropriate mobility and accessibility for specific recognition by NC. Our data also highlight the necessary plasticity of NCp7 to adapt to the sequence and structure variability of cTAR to chaperone its annealing with TAR through a specific pathway. PMID:23511968

  5. Axon injury triggers EFA-6 mediated destabilization of axonal microtubules via TACC and doublecortin like kinase.

    Science.gov (United States)

    Chen, Lizhen; Chuang, Marian; Koorman, Thijs; Boxem, Mike; Jin, Yishi; Chisholm, Andrew D

    2015-09-04

    Axon injury triggers a series of changes in the axonal cytoskeleton that are prerequisites for effective axon regeneration. In Caenorhabditis elegans the signaling protein Exchange Factor for ARF-6 (EFA-6) is a potent intrinsic inhibitor of axon regrowth. Here we show that axon injury triggers rapid EFA-6-dependent inhibition of axonal microtubule (MT) dynamics, concomitant with relocalization of EFA-6. EFA-6 relocalization and axon regrowth inhibition require a conserved 18-aa motif in its otherwise intrinsically disordered N-terminal domain. The EFA-6 N-terminus binds the MT-associated proteins TAC-1/Transforming-Acidic-Coiled-Coil, and ZYG-8/Doublecortin-Like-Kinase, both of which are required for regenerative growth cone formation, and which act downstream of EFA-6. After injury TAC-1 and EFA-6 transiently relocalize to sites marked by the MT minus end binding protein PTRN-1/Patronin. We propose that EFA-6 acts as a bifunctional injury-responsive regulator of axonal MT dynamics, acting at the cell cortex in the steady state and at MT minus ends after injury.

  6. Calpains mediate epithelial-cell death during mammary gland involution: mitochondria and lysosomal destabilization.

    Science.gov (United States)

    Arnandis, T; Ferrer-Vicens, I; García-Trevijano, E R; Miralles, V J; García, C; Torres, L; Viña, J R; Zaragozá, R

    2012-09-01

    Our aim was to elucidate the physiological role of calpains (CAPN) in mammary gland involution. Both CAPN-1 and -2 were induced after weaning and its activity increased in isolated mitochondria and lysosomes. CAPN activation within the mitochondria could trigger the release of cytochrome c and other pro-apoptotic factors, whereas in lysosomes it might be essential for tissue remodeling by releasing cathepsins into the cytosol. Immunohistochemical analysis localized CAPNs mainly at the luminal side of alveoli. During weaning, CAPNs translocate to the lysosomes processing membrane proteins. To identify these substrates, lysosomal fractions were treated with recombinant CAPN and cleaved products were identified by 2D-DIGE. The subunit b(2) of the v-type H(+) ATPase is proteolyzed and so is the lysosomal-associated membrane protein 2a (LAMP2a). Both proteins are also cleaved in vivo. Furthermore, LAMP2a cleavage was confirmed in vitro by addition of CAPNs to isolated lysosomes and several CAPN inhibitors prevented it. Finally, in vivo inhibition of CAPN1 in 72-h-weaned mice decreased LAMP2a cleavage. Indeed, calpeptin-treated mice showed a substantial delay in tissue remodeling and involution of the mammary gland. These results suggest that CAPNs are responsible for mitochondrial and lysosomal membrane permeabilization, supporting the idea that lysosomal-mediated cell death is a new hallmark of mammary gland involution.

  7. Pironetin reacts covalently with cysteine-316 of α-tubulin to destabilize microtubule

    Science.gov (United States)

    Yang, Jianhong; Wang, Yuxi; Wang, Taijing; Jiang, Jian; Botting, Catherine H.; Liu, Huanting; Chen, Qiang; Yang, Jinliang; Naismith, James H.; Zhu, Xiaofeng; Chen, Lijuan

    2016-01-01

    Molecules that alter the normal dynamics of microtubule assembly and disassembly include many anticancer drugs in clinical use. So far all such therapeutics target β-tubulin, and structural biology has explained the basis of their action and permitted design of new drugs. However, by shifting the profile of β-tubulin isoforms, cancer cells become resistant to treatment. Compounds that bind to α-tubulin are less well characterized and unexploited. The natural product pironetin is known to bind to α-tubulin and is a potent inhibitor of microtubule polymerization. Previous reports had identified that pironetin reacts with lysine-352 residue however analogues designed on this model had much lower potency, which was difficult to explain, hindering further development. We report crystallographic and mass spectrometric data that reveal that pironetin forms a covalent bond to cysteine-316 in α-tubulin via a Michael addition reaction. These data provide a basis for the rational design of α-tubulin targeting chemotherapeutics. PMID:27357539

  8. Endothelial Nlrp3 inflammasome activation associated with lysosomal destabilization during coronary arteritis.

    Science.gov (United States)

    Chen, Yang; Li, Xiang; Boini, Krishna M; Pitzer, Ashley L; Gulbins, Erich; Zhang, Yang; Li, Pin-Lan

    2015-02-01

    Inflammasomes play a critical role in the development of vascular diseases. However, the molecular mechanisms activating the inflammasome in endothelial cells and the relevance of this inflammasome activation is far from clear. Here, we investigated the mechanisms by which an Nlrp3 inflammasome is activated to result in endothelial dysfunction during coronary arteritis by Lactobacillus casei (L. casei) cell wall fragments (LCWE) in a mouse model for Kawasaki disease. Endothelial dysfunction associated with increased vascular cell adhesion protein 1 (VCAM-1) expression and endothelial-leukocyte adhesion was observed during coronary arteritis in mice treated with LCWE. Accompanied with these changes, the inflammasome activation was also shown in coronary arterial endothelium, which was characterized by a marked increase in caspase-1 activity and IL-1β production. In cultured endothelial cells, LCWE induced Nlrp3 inflammasome formation, caspase-1 activation and IL-1β production, which were blocked by Nlrp3 gene silencing or lysosome membrane stabilizing agents such as colchicine, dexamethasone, and ceramide. However, a potassium channel blocker glibenclamide or an oxygen free radical scavenger N-acetyl-l-cysteine had no effects on LCWE-induced inflammasome activation. LCWE also increased endothelial cell lysosomal membrane permeability and triggered lysosomal cathepsin B release into cytosol. Silencing cathepsin B blocked LCWE-induced Nlrp3 inflammasome formation and activation in endothelial cells. In vivo, treatment of mice with cathepsin B inhibitor also abolished LCWE-induced inflammasome activation in coronary arterial endothelium. It is concluded that LCWE enhanced lysosomal membrane permeabilization and consequent release of lysosomal cathepsin B, resulting in activation of the endothelial Nlrp3 inflammasome, which may contribute to the development of coronary arteritis.

  9. TWEAK inhibits TRAF2-mediated CD40 signaling by destabilization of CD40 signaling complexes.

    Science.gov (United States)

    Salzmann, Steffen; Lang, Isabell; Rosenthal, Alevtina; Schäfer, Viktoria; Weisenberger, Daniela; Carmona Arana, José Antonio; Trebing, Johannes; Siegmund, Daniela; Neumann, Manfred; Wajant, Harald

    2013-09-01

    We found recently that TNF-like weak inducer of apoptosis (TWEAK) and fibroblast growth factor-inducible-14 (Fn14) by virtue of their strong capability to reduce the freely available cytoplasmic pool of TNFR-associated factor (TRAF)2 and cellular inhibitors of apoptosis (cIAPs) antagonize the functions of these molecules in TNFR1 signaling, resulting in sensitization for apoptosis and inhibition of classical NF-κB signaling. In this study, we demonstrate that priming of cells with TWEAK also interferes with activation of the classical NF-κB pathway by CD40. Likewise, there was strong inhibition of CD40 ligand (CD40L)-induced activation of MAPKs in TWEAK-primed cells. FACS analysis and CD40L binding studies revealed unchanged CD40 expression and normal CD40L-CD40 interaction in TWEAK-primed cells. CD40L immunoprecipitates, however, showed severely reduced amounts of CD40 and CD40-associated proteins, indicating impaired formation or reduced stability of CD40L-CD40 signaling complexes. The previously described inhibitory effect of TWEAK on TNFR1 signaling has been traced back to reduced activity of the TNFR1-associated TRAF2-cIAP1/2 ubiquitinase complex and did not affect the stability of the immunoprecipitable TNFR1 receptor complex. Thus, the inhibitory effect of TWEAK on CD40 signaling must be based at least partly on other mechanisms. In line with this, signaling by the CD40-related TRAF2-interacting receptor TNFR2 was also attenuated but still immunoprecipitable in TWEAK-primed cells. Collectively, we show that Fn14 activation by soluble TWEAK impairs CD40L-CD40 signaling complex formation and inhibits CD40 signaling and thus identify the Fn14-TWEAK system as a potential novel regulator of CD40-related cellular functions.

  10. Mechanistic modeling of fingering, nonmonotonicity, fragmentation, and pulsation within gravity/buoyant destabilized two-phase/unsaturated flow

    Science.gov (United States)

    Glass, Robert J.; Yarrington, Lane

    2003-03-01

    Fingering, nonmonotonicity, fragmentation, and pulsation within gravity/buoyant destabilized two-phase/unsaturated flow systems has been widely observed with examples in homogeneous to heterogeneous porous media, in single fractures to fracture networks, and for both wetting and nonwetting invasion. To model this phenomena, we consider a mechanistic approach based on forms of modified invasion percolation (MIP) that include gravity, the influence of the local interfacial curvature along the phase-phase interface, and the simultaneous invasion and reinvasion of both wetting and nonwetting fluids. We present example simulations and compare them to experimental data for three very different situations: (1) downward gravity-driven fingering of water into a dry, homogeneous, water-wettable, porous medium; (2) upward buoyancy-driven migration of gas within a water saturated, heterogeneous, water-wettable, porous medium; and (3) downward gravity-driven fingering of water into a dry, water-wettable, rough-walled fracture.

  11. On resonant destabilization of toroidal Alfven eigenmodes by circulating and trapped energetic ions/alpha particles in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Biglari, H.; Zonca, F.; Chen, L.

    1991-10-01

    Toroidal Alfven eigenmodes are shown to be resonantly destabilized by both circulating and trapped energetic ions/alpha particles. In particular, the energetic circulating ions are shown to resonate with the mode not only at the Alfven speed ({upsilon}{sub A}), but also one-third of this speed, while resonances exist between trapped energetic ions and the wave when {upsilon} = {upsilon}{sub A}/21{epsilon}{sup {1/2}} (l=integer, {epsilon}=r/R is the local inverse aspect ratio), although the instability becomes weaker for resonances other than the fundamental. The oft-quoted criterion that instability requires super-Alfvenic ion velocities is thus sufficient but not necessary. 14 refs.

  12. Geomorphic consequences of two large glacier and rock glacier destabilizations in the Central and northern Chilean Andes

    Science.gov (United States)

    Iribarren Anacona, Pablo; Bodin, Xavier

    2010-05-01

    Mountain areas are occasionaly affected by complex mass movements of high magnitude and large extent, which generally involve water, snow, rock and ice in variable proportions. Those events can take the form of rock avalanche, landslide, debris flow, glacier collapse or a combination of these phenomenons. In the Central Andes of Chile, they affect hardly accessible regions with low population, explaining the scarcity of previous studies. Nevertheless, during the last 30 years, some documented examples of such events in this region have shown that the volume of material involved is in the order of several millions of m³, the areas affected can reach several tenth of km² and the velocity of the movement can exceed several tenths of m/s. In this context, this study intends i) to inventory and to describe the main characteristics of events previously documented in the Central Andes of Chile, and ii) analyse in detail two recent events (2005-2007) never described before which have affected in one case a glacier and in another case a rock glacier. With the objectives of determining the possible chain of triggering factors and interpreting the event's significance in terms of geomorphic, cryogenic and climatic dynamics, we used air photographs, satellite imagery (Landsat TM & ETM+; Quick Bird when available in Google Earth 5.0), data from the closest meteorological stations, glacier mass balance data and seismic records to investigate the collapse of a rock glacier occurred in 2006 on the west-facing flank of the Cerro Las Tórtolas (6160 m asl; 29°58' S. - 69°55' W.), in the arid North of Chile, and the collapse of a glacier that occurred during austral summer 2006-2007 on the South side of the Tinguiririca Volcano (4075 m asl; 34°48' S. - 70°21' W.). The rock glacier collapse of the Cerro Las Tórtolas West flank occurred during the spring of 2006, but signs of destabilization were already observable since the end of 2005. The deposit of the collapsed mass of the

  13. The microtubule destabilizing protein stathmin controls the transition from dividing neuronal precursors to postmitotic neurons during adult hippocampal neurogenesis.

    Science.gov (United States)

    Boekhoorn, Karin; van Dis, Vera; Goedknegt, Erika; Sobel, André; Lucassen, Paul J; Hoogenraad, Casper C

    2014-12-01

    The hippocampus is one of the two areas in the mammalian brain where adult neurogenesis occurs. Adult neurogenesis is well known to be involved in hippocampal physiological functions as well as pathophysiological conditions. Microtubules (MTs), providing intracellular transport, stability, and transmitting force, are indispensable for neurogenesis by facilitating cell division, migration, growth, and differentiation. Although there are several examples of MT-stabilizing proteins regulating different aspects of adult neurogenesis, relatively little is known about the function of MT-destabilizing proteins. Stathmin is such a MT-destabilizing protein largely restricted to the CNS, and in contrast to its developmental family members, stathmin is also expressed at significant levels in the adult brain, notably in areas involved in adult neurogenesis. Here, we show an important role for stathmin during adult neurogenesis in the subgranular zone of the mouse hippocampus. After carefully mapping stathmin expression in the adult dentate gyrus (DG), we investigated its role in hippocampal neurogenesis making use of stathmin knockout mice. Although hippocampus development appears normal in these animals, different aspects of adult neurogenesis are affected. First, the number of proliferating Ki-67+ cells is decreased in stathmin knockout mice, as well as the expression of the immature markers Nestin and PSA-NCAM. However, newborn cells that do survive express more frequently the adult marker NeuN and have a more mature morphology. Furthermore, our data suggest that migration in the DG might be affected. We propose a model in which stathmin controls the transition from neuronal precursors to early postmitotic neurons.

  14. The MitCHAP-60 disease is due to entropic destabilization of the human mitochondrial Hsp60 oligomer.

    Science.gov (United States)

    Parnas, Avital; Nadler, Michal; Nisemblat, Shahar; Horovitz, Amnon; Mandel, Hanna; Azem, Abdussalam

    2009-10-01

    The 60-kDa heat shock protein (mHsp60) is a vital cellular complex that mediates the folding of many of the mitochondrial proteins. Its function is executed in cooperation with the co-chaperonin, mHsp10, and requires ATP. Recently, the discovery of a new mHsp60-associated neurodegenerative disorder, MitCHAP-60 disease, has been reported. The disease is caused by a point mutation at position 3 (D3G) of the mature mitochondrial Hsp60 protein, which renders it unable to complement the deletion of the homologous bacterial protein in Escherichia coli (Magen, D., Georgopoulos, C., Bross, P., Ang, D., Segev, Y., Goldsher, D., Nemirovski, A., Shahar, E., Ravid, S., Luder, A., Heno, B., Gershoni-Baruch, R., Skorecki, K., and Mandel, H. (2008) Am. J. Hum. Genet. 83, 30-42). The molecular basis of the MitCHAP-60 disease is still unknown. In this study, we present an in vitro structural and functional analysis of the purified wild-type human mHsp60 and the MitCHAP-60 mutant. We show that the D3G mutation leads to destabilization of the mHsp60 oligomer and causes its disassembly at low protein concentrations. We also show that the mutant protein has impaired protein folding and ATPase activities. An additional mutant that lacks the first three amino acids (N-del), including Asp-3, is similarly impaired in refolding activity. Surprisingly, however, this mutant exhibits profound stabilization of its oligomeric structure. These results suggest that the D3G mutation leads to entropic destabilization of the mHsp60 oligomer, which severely impairs its chaperone function, thereby causing the disease.

  15. 缓蚀剂分子结构与抗硫性能及其缓蚀机理研究%RELATIONSHIP BETWEEN CHEMICAL MOLECULAR STRUCTURE AND ANTI-SULFUR PROPERTIES AND INHIBITION MECHANISM OF CORROSION INHIBITORS

    Institute of Scientific and Technical Information of China (English)

    刘月学; 刘烈炜; 董猛; 张大同

    2012-01-01

    用饱和H_2S/CO_2失重法、高压H_2S/CO_2动态失重法、原子力显微镜(AFM)、环境扫描电镜(SEM)和X射线能量色散光谱(EDX)研究了咪唑啉衍生物、曼尼希碱、吡啶季铵盐、喹啉季铵盐和新稠杂环季铵盐5种不同分子结构缓蚀剂对N80钢的抗硫性能。结果表明5种缓蚀剂对N80钢的抗硫性能均随缓蚀剂浓度的增加而增强,各缓蚀剂的抗硫性能优劣顺序为:新稠杂环季铵盐〉喹啉季铵盐〉吡啶季铵盐〉咪唑啉衍生物〉曼尼希碱。静电吸附作用较强、空间位阻效应较小且中心吸附原子的电子云密度较大的缓蚀剂抗硫效果更好,其缓蚀机理主要是有效抑制CO_2/Cl~-腐蚀且促使试片表面生成致密的硫化物保护膜。%The inhibitive properties of five kinds of corrosion inhibitors,which contain imidazoline derivative, mannich base,pyridine quaternary ammonium salt,quinoline quaternary ammonium salt and a new fused heterocycle quaternary ammonium salt were studied by means of mass loss of saturated H_2S/CO_2 and dynamic rotating with high-pressure of H_2S/CO_2,atomic force microscopy(AFM),environmental scanning electron microscope (SEM) and energy dispersive X-ray(EDX) analysis on N80 steel.The results showed that inhibitive properties of five kinds of inhibitors enhanced with the increase of their concentration.The excellent order of the inhibitors was as followed:the new fused heterocycle quaternary ammonium saltquinoline quaternary ammonium saltpyridine quaternary ammonium saltimidazoline derivativemannich base.Corrosion inhibitor which had stronger electrostatic adsorption,smaller steric hindrance effect and larger electron density of the adatom had the better anti-sulfur properties.The inhibition mechanism of corrosion inhibitor was to inhibit the corrosion of CO_2/C1~- and spur the formation of the compact sulfide film.

  16. Identification of fermentation inhibitors in wood hydrolyzates and removal of inhibitors by ion exchange and liquid-liquid extraction

    Science.gov (United States)

    Luo, Caidian

    1998-12-01

    Common methods employed in the ethanol production from biomass consist of chemical or enzymatic degradation of biomass into sugars and then fermentation of sugars into ethanol or other chemicals. However, some degradation products severely inhibit the fermentation processes and substantially reduce the efficiency of ethanol production. How to remove inhibitors from the reaction product mixture and increase the production efficiency are critical in the commercialization of any processes of energy from biomass. The present study has investigated anion exchange and liquid-liquid extraction as potential methods for inhibitor removal. An analytical method has been developed to identify the fermentation inhibitors in a hydrolyzate. The majority of inhibitors present in hybrid poplar hydrolyzate have positively been identified. Ion exchange with weak basic Dowex-MWA-1 resin has been proved to be an effective mean to remove fermentation inhibitors from hybrid poplar hydrolyzate and significantly increase the fermentation productivity. Extraction with n-butanol might be a preferred way to remove inhibitors from wood hydrolyzates and improve the fermentability of sugars in the hydrolyzates. n-Butanol also removes some glucose, mannose and xylose from the hydrolyzate. Inhibitor identification reveals that lignin and sugar degradation compounds including both aromatic and aliphatic aldehydes and carboxylic acids formed in hydrolysis, plus fatty acids and other components from wood extractives are major fermentation inhibitors in Sacchromyces cerevisiae fermentation. There are 35 components identified as fermentation inhibitors. Among them, 4-hydroxy benzoic acid, 3,4-dihydroxy benzoic acid, syringic acid, syringaldehyde, and ferulic acid are among the most abundant aromatic inhibitors in hybrid poplar hydrolyzate. The conversion of aldehyde groups into carboxylic acid groups in the nitric acid catalyzed hydrolysis reduces the toxicity of the hydrolyzate. A wide spectrum of

  17. Catechins and Procyanidins of Ginkgo biloba Show Potent Activities towards the Inhibition of β-Amyloid Peptide Aggregation and Destabilization of Preformed Fibrils

    Directory of Open Access Journals (Sweden)

    Haiyan Xie

    2014-04-01

    Full Text Available Catechins and procyanidins, together with flavonoid glycosides and terpene trilactones, are three important categories of components in the standard extract of Ginkgo biloba leaves (EGb761. In this research, catechins and proanthocyanidins were found to exist in both the extract of Ginkgo leaves and Ginkgo products. By comparing with reference compounds, six of them were identified as (+-catechin, (−-epicatechin, (−-gallocatechin, (−-epigallocatechin and procyanidins B1 and B3. The activities of these polyphenols in the inhibition of Aβ42 aggregation and the destabilization of preformed fibrils were evaluated using biochemical assays, which showed that all six of the polyphenols, as well as a fraction of the extract of Ginkgo biloba leaves (EGb containing catechins and procyanidins, exerted potent inhibitory activities towards Aβ42 aggregation and could also destabilize the performed fibrils. Catechins and procyanidins can therefore be regarded as the potent active constituents of EGb761 in terms of their inhibition of Aβ42 aggregation and destabilization of the fibrils. Although quantitative mass spectroscopic analysis revealed that the catechins and procyanidins are only present in low concentrations in EGb761, these components should be studied in greater detail because of their potent inhibitory effects towards Aβ42 aggregation and their ability to destabilize preformed fibrils, especially during the quality control of Ginkgo leaves and the manufacture of Ginkgo products.

  18. Catechins and procyanidins of Ginkgo biloba show potent activities towards the inhibition of β-amyloid peptide aggregation and destabilization of preformed fibrils.

    Science.gov (United States)

    Xie, Haiyan; Wang, Jing-Rong; Yau, Lee-Fong; Liu, Yong; Liu, Liang; Han, Quan-Bin; Zhao, Zhongzhen; Jiang, Zhi-Hong

    2014-04-22

    Catechins and procyanidins, together with flavonoid glycosides and terpene trilactones, are three important categories of components in the standard extract of Ginkgo biloba leaves (EGb761). In this research, catechins and proanthocyanidins were found to exist in both the extract of Ginkgo leaves and Ginkgo products. By comparing with reference compounds, six of them were identified as (+)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin and procyanidins B1 and B3. The activities of these polyphenols in the inhibition of Aβ42 aggregation and the destabilization of preformed fibrils were evaluated using biochemical assays, which showed that all six of the polyphenols, as well as a fraction of the extract of Ginkgo biloba leaves (EGb) containing catechins and procyanidins, exerted potent inhibitory activities towards Aβ42 aggregation and could also destabilize the performed fibrils. Catechins and procyanidins can therefore be regarded as the potent active constituents of EGb761 in terms of their inhibition of Aβ42 aggregation and destabilization of the fibrils. Although quantitative mass spectroscopic analysis revealed that the catechins and procyanidins are only present in low concentrations in EGb761, these components should be studied in greater detail because of their potent inhibitory effects towards Aβ42 aggregation and their ability to destabilize preformed fibrils, especially during the quality control of Ginkgo leaves and the manufacture of Ginkgo products.

  19. Destabilization and fusion of zwitterionic large unilamellar lipid vesicles induced by a beta-type structure of the HIV-1 fusion peptide

    NARCIS (Netherlands)

    Nieva, JL; Nir, S; Wilschut, J

    1998-01-01

    The peptide HIVarg, corresponding to a sequence of 23 amino acid residues at the N-terminus of HIV-1 gp41, has the capacity to induce fusion of large unilamellar vesicles (LUV) consisting of negatively charged or zwitterionic phospholipids. In the present study, we further characterize this destabil

  20. Quantum Chemical Studies on the Molecular Reactivity of Imidazoline Inhibitors%咪唑啉缓蚀剂分子反应活性的量子化学研究

    Institute of Scientific and Technical Information of China (English)

    郁金华; 史瑞莲

    2014-01-01

    In this article, 11 kinds of corrosion inhibitor molecules of imidazoline with the same alkyl long chain has been taken as the research objects. Using GGA /BLYP Method of DFT, reaction active sites of corrosion inhibitor molecule has been analyzed by calculating molecular quantitative parameters,such as frontier orbital distribution, charge distribution, orbital coefficient and Fukui index. The results indicated that the molecular reactivity area and active sites were mainly concentrated in the head of imidazoline molecules; the head of the imidazole ring and the heteroatom on hydrophilic substituent were the main active sites; S atoms had contributed enormously to HOMO and LUMO; at the same time S atoms was taken as nucleophilic and electrophilic active sites; with the number raising of S atoms, increased the reactivity sites and the corrosion efficiency; alkyl tail chain wasn’t affect the active distribution.%以11种同烷基链长咪唑啉类缓蚀剂分子为研究对象,采用DFT中的GGA/BLYP方法,通过计算分子的前线轨道分布、电荷分布、轨道系数、Fukui指数等,分析缓蚀剂分子位点的反应活性。结果表明,分子的反应活性区域和活性位点主要集中在咪唑啉分子头部的咪唑环和亲水取代基上的杂原子;S原子可同时作为亲核、亲电活性位,缓蚀效率随分子中S原子的增多而增加;烷基尾链对其活性分布基本不产生影响。

  1. Resistance to AHAS inhibitor herbicides: current understanding.

    Science.gov (United States)

    Yu, Qin; Powles, Stephen B

    2014-09-01

    Acetohydroxyacid synthase (AHAS) inhibitor herbicides currently comprise the largest site-of-action group (with 54 active ingredients across five chemical groups) and have been widely used in world agriculture since they were first introduced in 1982. Resistance evolution in weeds to AHAS inhibitors has been rapid and identified in populations of many weed species. Often, evolved resistance is associated with point mutations in the target AHAS gene; however non-target-site enhanced herbicide metabolism occurs as well. Many AHAS gene resistance mutations can occur and be rapidly enriched owing to a high initial resistance gene frequency, simple and dominant genetic inheritance and lack of major fitness cost of the resistance alleles. Major advances in the elucidation of the crystal structure of the AHAS (Arabidopsis thaliana) catalytic subunit in complex with various AHAS inhibitor herbicides have greatly improved current understanding of the detailed molecular interactions between AHAS, cofactors and herbicides. Compared with target-site resistance, non-target-site resistance to AHAS inhibitor herbicides is less studied and hence less understood. In a few well-studied cases, non-target-site resistance is due to enhanced rates of herbicide metabolism (metabolic resistance), mimicking that occurring in tolerant crop species and often involving cytochrome P450 monooxygenases. However, the specific herbicide-metabolising, resistance-endowing genes are yet to be identified in resistant weed species. The current state of mechanistic understanding of AHAS inhibitor herbicide resistance is reviewed, and outstanding research issues are outlined.

  2. Mo Isotopes Record Destabilization of a Stratified Ocean at the Precambrian-Cambrian Boundary

    Science.gov (United States)

    Wille, M.; Nägler, T. F.; Schröder, S.; Lehmann, B.; Kramers, J. D.

    2007-12-01

    Here we present Mo isotope signatures in black shales from two sample sets (Ara group, Oman and Yangtze Platform, China) which were deposited at and shortly after the Precambrian-Cambrian boundary (PC-C). At the first view, the overall Mo isotopic signatures (delta98/95Mo) of the Early Cambrian black shales is 1.2 permil below recent ocean water, similar to the signature found in Mesoproterozoic shales (Arnold et al. 2004), indicating a larger proportion of Mo sedimentation under strongly euxinic conditions compared to recent oceans. A chemically stratified ocean with sulfidic deep waters and modestly oxygenated surface waters as proposed by Canfield (1998) for the Paleoproterozoic and Mesoproterozoic ocean, and Jiang et al. (2007) reported Carbon isotope data from the Ediacaran Yangtze platform (635-542 Ma) to be consistent with long-term deep ocean anoxia/euxinia. A stratified ocean therefore provides a plausible scenario to explain our new PC-C Mo isotope data. On closer inspection, a transient Mo isotopic signal following immediately after the PC-C boundary in both sample sets indicates a short but intense global non-steady state situation. In particular, a short term, drastic decrease of the Mo ocean inventory to almost zero is required to reconcile the observed Mo isotope data. Combined with the extreme Mo enrichment, found in the Chinese sulfide marker bed at the PC-C boundary, this signal has to be explained with a non-uniformitarian Mo scavenging mechanism. We put forward the hypothesis of mixing of oxidized, i.e. Mo rich surface waters with upwelling euxinic bottom water masses of the stratified ocean, as H2S is the most efficient Mo scavenging reagent. This scenario not only explains the transient isotopic signal, it can also be responsible for the sudden extinction of the Ediacaran fauna by H2S poisoning. In contrast, mass extinction scenarios like bolide impact, flood basalt eruptions or methane release, do not provide a direct explanation for the

  3. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  4. Destabilization of acrosome and elastase influence mediate the release of secretory phospholipase A2 from human spermatozoa

    Institute of Scientific and Technical Information of China (English)

    Jacqueline Leβig; Uta Reibetanz; Jürgen Arnhold; Hans-Jürgen Glander

    2008-01-01

    Aim: To determine the cellular distribution of secretory phospholipase A2 (sPLA2) in dependence on the acrosomal state and under the action of elastase released under inflammatory processes from leukocytes. Methods: Acrosome reaction of spermatozoa was triggered by calcimycin. Human leukocyte elastase was used to simulate in flammatory conditions. To visualize the distribution of sPLA2 and to determine the acrosomal state, immunofluorescence tech-niques and lectin binding combined with confocal laser scanning fluorescence microscopy and flow cytometry were used. Results: Although sPLA2 was detected at the acrosome and tail regions in intact spermatozoa, it disappearedfrom the head region after triggering the acrosome reaction. This release of sPLA2 was associated with enhanced binding of annexin V-fluoroscein isothiocyanate (FITC) to spermatozoa surfaces, intercalation of ethidium-homodimer L and bnding of FITC-iabelled concanavalin A at the acrosomal region. Spermatozoa from healthy subjects treated with elastase were characterized by release of sPLA2, disturbance of acrosome structure, and loss of vitality. Conclusion:The ability of spermatozoa to release secretory phospholipase A2 is related to the acrosomal state. Premature destabi-lization of the acrosome and loss of sPLA2 can occur during silent inflammations in the male genital tract. The distribution pattern of sPLA2 in intact spermatozoa might be an additional parameter for evaluating sperm quality.

  5. Decrease in pH destabilizes individual vault nanocages by weakening the inter-protein lateral interaction

    Science.gov (United States)

    Llauró, Aida; Guerra, Pablo; Kant, Ravi; Bothner, Brian; Verdaguer, Núria; de Pablo, Pedro J.

    2016-10-01

    Vault particles are naturally occurring proteinaceous cages with promising application as molecular containers. The use of vaults as functional transporters requires a profound understanding of their structural stability to guarantee the protection and controlled payload delivery. Previous results performed with bulk techniques or at non-physiological conditions have suggested pH as a parameter to control vault dynamics. Here we use Atomic Force Microscopy (AFM) to monitor the structural evolution of individual vault particles while changing the pH in real time. Our experiments show that decreasing the pH of the solution destabilize the barrel region, the central part of vault particles, and leads to the aggregation of the cages. Additional analyses using Quartz-Crystal Microbalance (QCM) and Differential Scanning Fluorimetry (DSF) are consistent with our single molecule AFM experiments. The observed topographical defects suggest that low pH weakens the bonds between adjacent proteins. We hypothesize that the observed effects are related to the strong polar character of the protein-protein lateral interactions. Overall, our study unveils the mechanism for the influence of a biologically relevant range of pHs on the stability and dynamics of vault particles.

  6. Microtubule Destabilizer KIF2A Undergoes Distinct Site-Specific Phosphorylation Cascades that Differentially Affect Neuronal Morphogenesis

    Directory of Open Access Journals (Sweden)

    Tadayuki Ogawa

    2015-09-01

    Full Text Available Neurons exhibit dynamic structural changes in response to extracellular stimuli. Microtubules (MTs provide rapid and dramatic cytoskeletal changes within the structural framework. However, the molecular mechanisms and signaling networks underlying MT dynamics remain unknown. Here, we have applied a comprehensive and quantitative phospho-analysis of the MT destabilizer KIF2A to elucidate the regulatory mechanisms of MT dynamics within neurons in response to extracellular signals. Interestingly, we identified two different sets of KIF2A phosphorylation profiles that accelerate (A-type and brake (B-type the MT depolymerization activity of KIF2A. Brain-derived neurotrophic factor (BDNF stimulates PAK1 and CDK5 kinases, which decrease the MT depolymerizing activity of KIF2A through B-type phosphorylation, resulting in enhanced outgrowth of neural processes. In contrast, lysophosphatidic acid (LPA induces ROCK2 kinase, which suppresses neurite outgrowth from round cells via A-type phosphorylation. We propose that these two mutually exclusive forms of KIF2A phosphorylation differentially regulate neuronal morphogenesis during development.

  7. Establishing a High-content Analysis Method for Tubulin Polymerization to Evaluate Both the Stabilizing and Destabilizing Activities of Compounds.

    Science.gov (United States)

    Sum, Chi Shing; Nickischer, Debra; Lei, Ming; Weston, Andrea; Zhang, Litao; Schweizer, Liang

    2014-01-01

    Microtubules are important components of the cellular cytoskeleton that play roles in various cellular processes such as vesicular transport and spindle formation during mitosis. They are formed by an ordered organization of α-tubulin and β-tubulin hetero-polymers. Altering microtubule polymerization has been known to be the mechanism of action for a number of therapeutically important drugs including taxanes and epothilones. Traditional cell-based assays for tubulin-interacting compounds rely on their indirect effects on cell cycle and/or cell proliferation. Direct monitoring of compound effects on microtubules is required to dissect detailed mechanisms of action in a cellular setting. Here we report a high-content assay platform to monitor tubulin polymerization status by directly measuring the acute effects of drug candidates on the cellular tubulin network with the capability to dissect the mechanisms of action. This high-content analysis distinguishes in a quantitative manner between compounds that act as tubulin stabilizers versus those that are tubulin destabilizers. In addition, using a multiplex approach, we expanded this analysis to simultaneously monitor physiological cellular responses and associated cellular phenotypes.

  8. Synthesis and evaluation of indazole based analog sensitive Akt inhibitors.

    Science.gov (United States)

    Okuzumi, Tatsuya; Ducker, Gregory S; Zhang, Chao; Aizenstein, Brian; Hoffman, Randy; Shokat, Kevan M

    2010-08-01

    The kinase Akt is a key signaling node in regulating cellular growth and survival. It is implicated in cancer by mutation and its role in the downstream transmission of aberrant PI3K signaling. For these reasons, Akt has become an increasingly important target of drug development efforts and several inhibitors are now reaching clinical trials. Paradoxically it has been observed that active site kinase inhibitors of Akt lead to hyperphosphorylation of Akt itself. To investigate this phenomenon we here describe the application of a chemical genetics strategy that replaces native Akt with a mutant version containing an active site substitution that allows for the binding of an engineered inhibitor. This analog sensitive strategy allows for the selective inhibition of a single kinase. In order to create the inhibitor selective for the analog sensitive kinase, a diversity of synthetic approaches was required, finally resulting in the compound PrINZ, a 7-substituted version of the Abbott Labs Akt inhibitor A-443654.

  9. Cholinesterase inhibitors from botanicals

    Directory of Open Access Journals (Sweden)

    Faiyaz Ahmed

    2013-01-01

    Full Text Available Alzheimer′s disease (AD is a progressive neurodegenerative disease, wherein a progressive loss of cholinergic synapses occurs in hippocampus and neocortex. Decreased concentration of the neurotransmitter, acetylcholine (ACh, appears to be critical element in the development of dementia, and the most appropriate therapeutic approach to treat AD and other form of dementia is to restore acetylcholine levels by inhibiting both major form of cholinesterase: Acetylcholinesterase (AChE and butyrylcholinesterase (BChE. Consequently, researches have focused their attention towards finding cholinesterase inhibitors from natural products. A large number of such inhibitors have been isolated from medicinal plants. This review presents a comprehensive account of the advances in field of cholinesterase inhibitor phytoconstituents. The structures of some important phytoconstituents (collected through www.Chemspider.com are also presented and the scope for future research is discussed.

  10. An Isochemogenic Set of Inhibitors To Define the Therapeutic Potential of Histone Deacetylases in β-Cell Protection

    DEFF Research Database (Denmark)

    Wagner, Florence F; Lundh, Morten; Kaya, Taner;

    2016-01-01

    of highly potent and isoform-selective class I HDAC inhibitors, rationally designed by exploiting minimal structural changes to the clinically experienced HDAC inhibitor CI-994. We used this toolkit of isochemogenic or chemically matched inhibitors to probe the role of class I HDACs in β-cell pathobiology...

  11. [Amylase inhibitors from Streptomyces lucensis VKPM Ac-1743 and Streptomyces violaceus VKPM Ac-1734].

    Science.gov (United States)

    Sharova, N Iu

    2015-01-01

    Inhibitors synthesized by the Streptomyces lucensis VKPM AS-1743 and Streptomyces violaceus VKPM AS-1734 strains were studied for their influence on amylases of different origin. The effect of the inhibitors was shown to be different on fungal amylase, pancreatic amylase, and amylase from human blood. It has been found that the studied inhibitors are substances of a pseudooligosaccharide nature and exhibit their activity and stability over a wide range of pH and temperature values. The physico-chemical and biochemical properties of isolated inhibitors were compared with those of known microbial inhibitors of α-glucosidases.

  12. Thrombin inhibitor design.

    Science.gov (United States)

    Sanderson, P E; Naylor-Olsen, A M

    1998-08-01

    Recently, iv formulated direct thrombin inhibitors have been shown to be safe and efficacious alternatives to heparin. These results have fueled the hopes for an orally active compound. Such a compound could be a significant advance over warfarin if it had predictable pharmacokinetics and a duration of action sufficient for once or twice a day dosing. In order to develop an orally active compound which meets these criteria, the deficiencies of the prototype inhibitor efegatran have had to be addressed. First, using a combination of structure based design and empirical structure optimization, more selective compounds have been identified by modifying the P1 group or by incorporating different peptidomimetic P2/P3 scaffolds. Secondly, this optimization has resulted in the development of potent and selective non-covalent inhibitors, thus bypassing the liabilities of the serine trap. Thirdly, oral bioavailability has been achieved while maintaining selectivity and efficacy through the incorporation of progressively less basic P1 groups. The duration of action of these compounds remains to be optimized. Other advances in thrombin inhibitor design have included the development of uncharged P1 groups and the discovery of two non-peptide templates.

  13. ACE inhibitors and proteinuria

    NARCIS (Netherlands)

    Gansevoort, RT; deZeeuw, D; deJong, PE

    1996-01-01

    This review discusses the clinical consequences of urinary protein loss and the effects of inhibitors of the angiotensin converting enzyme (ACE) on this clinical finding. Proteinuria appears to be an important risk factor for renal function deterioration and for cardiovascular mortality. ACE inhibit

  14. Transglutaminase inhibitor from milk

    NARCIS (Netherlands)

    Jong, G.A.H. de; Wijngaards, G.; Koppelman, S.J.

    2003-01-01

    Cross-linking experiments of skimmed bovine milk with bacterial transglutaminase isolated from Streptoverticillium mobaraense showed only some degree of formation of high-molecular-weight casein polymers. Studies on the nature of this phenomenon revealed that bovine milk contains an inhibitor of tra

  15. Inhibitors of histone demethylases

    DEFF Research Database (Denmark)

    Lohse, Brian; Kristensen, Jesper L; Kristensen, Line H;

    2011-01-01

    Methylated lysines are important epigenetic marks. The enzymes involved in demethylation have recently been discovered and found to be involved in cancer development and progression. Despite the relative recent discovery of these enzymes a number of inhibitors have already appeared. Most of the i...

  16. Inhibitors of histone deacetylase

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to compounds of formula (I) or a pharmaceutically acceptable salt, hydrate, solvate, or prodrug thereof, wherein X1, X2, X3, X4, X5, W1, W2, W3, and W4 are as described. The present invention relates generally to inhibitors of histone deacetylase and to methods...

  17. Polycyclic aromatic hydrocarbon body residues and lysosomal membrane destabilization in mussels exposed to the Dubai Star bunker fuel oil (intermediate fuel oil 380) spill in San Francisco Bay.

    Science.gov (United States)

    Hwang, Hyun-Min; Stanton, Beckye; McBride, Toby; Anderson, Michael J

    2014-05-01

    Following the spill of bunker fuel oil (intermediate fuel oil 380, approximately 1500-3000 L) into San Francisco Bay in October 2009, polycyclic aromatic hydrocarbon (PAH) concentrations in mussels from moderately oiled areas increased up to 87 554 ng/g (dry wt) and, 3 mo later, decreased to concentrations found in mussels collected prior to oiling, with a biological half-life of approximately 16 d. Lysosomal membrane destabilization increased in mussels with higher PAH body burdens.

  18. Analysis of Alfvén eigenmode destabilization by energetic particles in Large Helical Device using a Landau-closure model

    Science.gov (United States)

    Varela, J.; Spong, D. A.; Garcia, L.

    2017-04-01

    Energetic particle populations in nuclear fusion experiments can destabilize the Alfvén Eigenmodes through inverse Landau damping and couplings with gap modes in the shear Alfvén continua. We use the reduced MHD equations to describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles. We add the Landau damping and resonant destabilization effects using a closure relation. We apply the model to study the Alfvén mode stability in the inward-shifted configurations of the Large Helical Device (LHD), performing a parametric analysis of the energetic particle β ({βf} ) in a range of realistic values, the ratios of the energetic particle thermal/Alfvén velocities ({{V}\\text{th}}/{{V}A0} ), the magnetic Lundquist numbers (S) and the toroidal modes (n). The n  =  1 and n  =  2 TAEs are destabilized, although the n  =  3 and n  =  4 TAEs are weakly perturbed. The most unstable configurations are associated with the density gradients of energetic particles in the plasma core: the TAEs are destabilized, even for small energetic particle populations, if their thermal velocity is lower than 0.4 times the Alfvén velocity. The frequency range of MHD bursts measured in the LHD are 50–70 kHz for the n  =  1 and 60–80 kHz for the n  =  2 TAE, which is consistent with the model predictions. ).

  19. Bile Acids Function Synergistically To Repress Invasion Gene Expression in Salmonella by Destabilizing the Invasion Regulator HilD.

    Science.gov (United States)

    Eade, Colleen R; Hung, Chien-Che; Bullard, Brian; Gonzalez-Escobedo, Geoffrey; Gunn, John S; Altier, Craig

    2016-08-01

    Salmonella spp. are carried by and can acutely infect agricultural animals and humans. After ingestion, salmonellae traverse the upper digestive tract and initiate tissue invasion of the distal ileum, a virulence process carried out by the type III secretion system encoded within Salmonella pathogenicity island 1 (SPI-1). Salmonellae coordinate SPI-1 expression with anatomical location via environmental cues, one of which is bile, a complex digestive fluid that causes potent repression of SPI-1 genes. The individual components of bile responsible for SPI-1 repression have not been previously characterized, nor have the bacterial signaling processes that modulate their effects been determined. Here, we characterize the mechanism by which bile represses SPI-1 expression. Individual bile acids exhibit repressive activity on SPI-1-regulated genes that requires neither passive diffusion nor OmpF-mediated entry. By using genetic methods, the effects of bile and bile acids were shown to require the invasion gene transcriptional activator hilD and to function independently of known upstream signaling pathways. Protein analysis techniques showed that SPI-1 repression by bile acids is mediated by posttranslational destabilization of HilD. Finally, we found that bile acids function synergistically to achieve the overall repressive activity of bile. These studies demonstrate a common mechanism by which diverse environmental cues (e.g., certain short-chain fatty acids and bile acids) inhibit SPI-1 expression. These data provide information relevant to Salmonella pathogenesis during acute infection in the intestine and during chronic infection of the gallbladder and inform the basis for development of therapeutics to inhibit invasion as a means of repressing Salmonella pathogenicity.

  20. Time-dependent loss of mitochondrial function precedes progressive histologic cartilage degeneration in a rabbit meniscal destabilization model.

    Science.gov (United States)

    Goetz, Jessica E; Coleman, Mitchell C; Fredericks, Douglas C; Petersen, Emily; Martin, James A; McKinley, Todd O; Tochigi, Yuki

    2017-03-01

    The goals of this work were to characterize progression of osteoarthritic cartilage degeneration in a rabbit medial meniscus destabilization (MMD) model and then to use the model to identify pre-histologic disruptions in chondrocyte metabolism under chronically elevated joint contact stresses in vivo. To characterize PTOA progression, 24 rabbits received either MMD or sham surgery. Limb loading was analyzed preoperatively and at regular postoperative intervals using a Tekscan pressure-sensitive walkway. Animals were euthanized 8 (n = 8 MMD; n = 8 sham) or 26 weeks (n = 8 MMD) postoperatively for histological cartilage evaluation by an objective, semi-automated Mankin scoring routine. To examine pre-histologic pathology, MMD was performed on an additional 20 rabbits, euthanized 1 (n = 9) or 4 weeks (n = 10) postoperatively. Chondrocytes were harvested fresh for measurement of mitochondrial function, an intracellular indicator of pathology after mechanical injury. Both MMD and sham surgery caused slight decreases in limb loading which returned to preoperative levels after 2 weeks. Histologically apparent cartilage damage progressed from 8 to 26 weeks after MMD. Changes in chondrocyte respiration were variable at 1 week, but by 4 weeks postoperatively chondrocyte mitochondrial function was significantly reduced. Many human injuries that lead to PTOA are relatively mild, and the cell-level mechanisms leading to disease remain unclear. We have documented PTOA progression in an animal model of subtle joint injury under continued use, and demonstrated that this model provides a realistic environment for investigation of multi-stage cellular pathology that develops prior to overt tissue degeneration and which could be targeted for disease modifying treatments. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:590-599, 2017.

  1. Protein homeostasis disorders of key enzymes of amino acids metabolism: mutation-induced protein kinetic destabilization and new therapeutic strategies.

    Science.gov (United States)

    Pey, Angel L

    2013-12-01

    Many inborn errors of amino acids metabolism are caused by single point mutations affecting the ability of proteins to fold properly (i.e., protein homeostasis), thus leading to enzyme loss-of-function. Mutations may affect protein homeostasis by altering intrinsic physical properties of the polypeptide (folding thermodynamics, and rates of folding/unfolding/misfolding) as well as the interaction of partially folded states with elements of the protein homeostasis network (such as molecular chaperones and proteolytic machineries). Understanding these mutational effects on protein homeostasis is required to develop new therapeutic strategies aimed to target specific features of the mutant polypeptide. Here, I review recent work in three different diseases of protein homeostasis associated to inborn errors of amino acids metabolism: phenylketonuria, inherited homocystinuria and primary hyperoxaluria type I. These three different genetic disorders involve proteins operating in different cell organelles and displaying different structural complexities. Mutations often decrease protein kinetic stability of the native state (i.e., its half-life for irreversible denaturation), which can be studied using simple kinetic models amenable to biophysical and biochemical characterization. Natural ligands and pharmacological chaperones are shown to stabilize mutant enzymes, thus supporting their therapeutic application to overcome protein kinetic destabilization. The role of molecular chaperones in protein folding and misfolding is also discussed as well as their potential pharmacological modulation as promising new therapeutic approaches. Since current available treatments for these diseases are either burdening or only successful in a fraction of patients, alternative treatments must be considered covering studies from protein structure and biophysics to studies in animal models and patients.

  2. Destabilized bioluminescent proteins

    Science.gov (United States)

    Allen, Michael S.; Rakesh, Gupta; Gary, Sayler S.

    2007-07-31

    Purified nucleic acids, vectors and cells containing a gene cassette encoding at least one modified bioluminescent protein, wherein the modification includes the addition of a peptide sequence. The duration of bioluminescence emitted by the modified bioluminescent protein is shorter than the duration of bioluminescence emitted by an unmodified form of the bioluminescent protein.

  3. The Influence of Oblique Angle Forced Exercise in Surgically Destabilized Stifle Joints Is Synergistic with Bone, but Antagonistic with Cartilage in an Ovine Model of Osteoarthritis.

    Science.gov (United States)

    Hill, Rachel J; Mason, Holly M; Yeip, Gavin; Merchant, Samer S; Olsen, Aaron L; Stott, Rusty D; Van Wettere, Arnaud J; Bressel, Eadric; Mason, Jeffrey B

    2017-01-01

    Large animal models of osteoarthritis are a necessary testing ground for FDA approval of human medicine applications. Sheep models have advantages over other available large animals, but development and progression of osteoarthritis in sheep is exceedingly slow, which handicaps progress in development of potential treatments. We combined oblique angle forced exercise to increase stress on the stifle, with surgical destabilization to hasten the development of osteoarthritis in ewes. Methods for early detection of clinical signs included radiography, urine, and serum biomarker assays and gait analysis and ex vivo we used microcomputed tomography and macroscopic joint analysis. Our model was able to produce clinically detectable signs of osteoarthritis in a relatively short period (14 weeks). Changes in bone were highly correlated between microcomputed tomography and radiographic analysis and changes in cartilage correlated well between urinary glycosaminoglycan levels and serum aggrecanase analyses. Exercise improved the negative effects of destabilization in bone but exacerbated the negative effects of destabilization in cartilage. These observations suggest that we may need to consider treatments for bone and cartilage separately. These results represent an improved large animal model of osteoarthritis with rapid onset of disease and superior detection of bone and soft tissue changes.

  4. Design and synthesis of human ABCB1 (P-glycoprotein) inhibitors by peptide coupling of diverse chemical scaffolds on carboxyl and amino termini of (S)-valine-derived thiazole amino acid.

    Science.gov (United States)

    Singh, Satyakam; Prasad, Nagarajan Rajendra; Chufan, Eduardo E; Patel, Bhargav A; Wang, Yi-Jun; Chen, Zhe-Sheng; Ambudkar, Suresh V; Talele, Tanaji T

    2014-05-22

    P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 μM) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [(125)I]-iodoarylazidoprazosin with IC50 = 0.75 μM and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 μM). Compound 28 at 3 μM reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp.

  5. APC mutations as a potential biomarker for sensitivity to tankyrase inhibitors in colorectal cancer.

    Science.gov (United States)

    Tanaka, Noritaka; Mashima, Tetsuo; Mizutani, Anna; Sato, Ayana; Aoyama, Aki; Gong, Bo; Yoshida, Haruka; Muramatsu, Yukiko; Nakata, Kento; Matsuura, Masaaki; Katayama, Ryohei; Nagayama, Satoshi; Fujita, Naoya; Sugimoto, Yoshikazu; Seimiya, Hiroyuki

    2017-02-08

    In most colorectal cancers (CRCs), Wnt/β-catenin signaling is activated by loss-of-function mutations in the adenomatous polyposis coli (APC) gene and plays a critical role in tumorigenesis. Tankyrases poly(ADP-ribosyl)ate and destabilize Axins, a negative regulator of β-catenin, and upregulate β-catenin signaling. Tankyrase inhibitors downregulate β-catenin and are expected to be promising therapeutics for CRC. However, CRC cells are not always sensitive to tankyrase inhibitors, and predictive biomarkers for the drug sensitivity remain elusive. Here we demonstrate that the short-form APC mutations predict the sensitivity of CRC cells to tankyrase inhibitors. By using well-established CRC cell lines, we found that tankyrase inhibitors downregulated β-catenin in the drug-sensitive but not resistant CRC cells. The drug-sensitive cells showed higher Tcf/LEF transcriptional activity than the resistant cells and possessed 'short' truncated APCs lacking all seven β-catenin-binding 20-amino-acid repeats (20-AARs). By contrast, the drug-resistant cells possessed 'long' APC retaining two or more 20-AARs. Knockdown of the long APCs with two 20-AARs increased β-catenin, Tcf/LEF transcriptional activity and its target gene AXIN2 expression. Under these conditions, tankyrase inhibitors were able to downregulate β-catenin in the resistant cells. These results indicate that the long APCs are hypomorphic mutants whereas they exert a dominant-negative effect on Axin-dependent β-catenin degradation caused by tankyrase inhibitors. Finally, we established 16 patient-derived CRC cells and confirmed that the tankyrase inhibitor-responsive cells harbor the short-form APC mutations. These observations exemplify the predictive importance of APC mutations, the most common genetic alteration in CRCs, for molecular targeted therapeutics.

  6. Validation of chemical compound library screening for transcriptional co-activator with PDZ-binding motif inhibitors using GFP-fused transcriptional co-activator with PDZ-binding motif.

    Science.gov (United States)

    Nagashima, Shunta; Maruyama, Junichi; Kawano, Shodai; Iwasa, Hiroaki; Nakagawa, Kentaro; Ishigami-Yuasa, Mari; Kagechika, Hiroyuki; Nishina, Hiroshi; Hata, Yutaka

    2016-06-01

    Transcriptional co-activator with PDZ-binding motif (TAZ) plays versatile roles in cell proliferation and differentiation. It is phosphorylated by large tumor suppressor kinases, the core kinases of the tumor-suppressive Hippo pathway. Phosphorylation induces the cytoplasmic accumulation of TAZ and its degradation. In human cancers, the deregulation of the Hippo pathway and gene amplification enhance TAZ activity. TAZ interacts with TEA domain family members (TEAD), and upregulates genes implicated in epithelial-mesenchymal transition. It also confers stemness to cancer cells. Thus, TAZ activation provides cancer cells with malignant properties and worsens the clinical prognosis. Therefore, TAZ attracts attention as a therapeutic target in cancer therapy. We applied 18 606 small chemical compounds to human osteosarcoma U2OS cells expressing GFP-fused TAZ (GFP-TAZ), monitored the subcellular localization of GFP-TAZ, and selected 33 compounds that shifted GFP-TAZ to the cytoplasm. Unexpectedly, only a limited number of compounds suppressed TAZ-mediated enhancement of TEAD-responsive reporter activity. Moreover, the compounds that weakened TEAD reporter activity did not necessarily decrease the unphosphorylated TAZ. In this study, we focused on three compounds that decreased both TEAD reporter activity and unphosphorylated TAZ, and treated several human cancer cells with these compounds. One compound did not show a remarkable effect, whereas the other two compounds compromised the cell viability in certain cancer cells. In conclusion, the GFP-TAZ-based assay can be used as the first screening for compounds that inhibit TAZ and show anticancer properties. To develop anticancer drugs, we need additional assays to select the compounds.

  7. Inhibitors of the Cellular Trafficking of Ricin

    Directory of Open Access Journals (Sweden)

    Daniel Gillet

    2012-01-01

    Full Text Available Throughout the last decade, efforts to identify and develop effective inhibitors of the ricin toxin have focused on targeting its N-glycosidase activity. Alternatively, molecules disrupting intracellular trafficking have been shown to block ricin toxicity. Several research teams have recently developed high-throughput phenotypic screens for small molecules acting on the intracellular targets required for entry of ricin into cells. These screens have identified inhibitory compounds that can protect cells, and sometimes even animals against ricin. We review these newly discovered cellular inhibitors of ricin intoxication, discuss the advantages and drawbacks of chemical-genetics approaches, and address the issues to be resolved so that the therapeutic development of these small-molecule compounds can progress.

  8. Benzoylurea Chitin Synthesis Inhibitors.

    Science.gov (United States)

    Sun, Ranfeng; Liu, Chunjuan; Zhang, Hao; Wang, Qingmin

    2015-08-12

    Benzoylurea chitin synthesis inhibitors are widely used in integrated pest management (IPM) and insecticide resistance management (IRM) programs due to their low toxicity to mammals and predatory insects. In the past decades, a large number of benzoylurea derivatives have been synthesized, and 15 benzoylurea chitin synthesis inhibitors have been commercialized. This review focuses on the history of commercial benzolyphenylureas (BPUs), synthetic methods, structure-activity relationships (SAR), action mechanism research, environmental behaviors, and ecotoxicology. Furthermore, their disadvantages of high risk to aquatic invertebrates and crustaceans are pointed out. Finally, we propose that the para-substituents at anilide of benzoylphenylureas should be the functional groups, and bipartite model BPU analogues are discussed in an attempt to provide new insight for future development of BPUs.

  9. Sequencing of aromatase inhibitors

    OpenAIRE

    2005-01-01

    Since the development of the third-generation aromatase inhibitors (AIs), anastrozole, letrozole and exemestane, these agents have been the subject of intensive research to determine their optimal use in advanced breast cancer. Not only have they replaced progestins in second-line therapy and challenged the role of tamoxifen in first-line, but there is also evidence for a lack of cross-resistance between the steroidal and nonsteroidal AIs, meaning that they may be used in sequence to obtain p...

  10. Update on Aromatase Inhibitors

    Directory of Open Access Journals (Sweden)

    Seifert-Klauss V

    2015-01-01

    Full Text Available Aromatase inhibitors (AI block the last phase of estrogen production in many types of tissues which express the enzym aromatase, among them muscle, liver, adrenal, brain and fat. The enzyme catalyzes the last step of the biosynthesis of the estrogens, i. e. the aromatisation of testosterone to estradiol and of androstendion to estrone. Aromatase is localized in the membrane of the endoplasmatic reticulum and is also produced in the placenta and the gonads. Mutations in the gene CYP19A1, which codes for aromatase, can lead either to lack or excess of aromatase. Gene polymorphisms also influence the amount of bioavailable estrogen and bone density.br Indications: AI are approved for the treatment of postmenopausal women with hormone receptor positive breast cancer, both in the adjuvant setting as well as after recurrence and in progressive disease. In premenopausal and in perimenopausal women AI cause an increased sensitivity of the ovaries to follicle stimulating hormone (FSH and can thereby lead to a boosted estrogen answer – this effect is particularly pronounced in early perimenopausal women – so that these situations demand a combination with GnRH-analogue if AI treatment is to be initiated. Alternatively, tamoxifene may be used in premenopausal patients, with or without GnRH analogues. Treatment of premenopausal patients with hormone receptor positive breast cancer with aromatase inhibiting therapy alone constitutes an absolute contraindication. Aromatase inhibitors do not lead to estrogen receptor downregulation or block the receptor such as tamoxifene. An exceptional application is the application in reproductive medicine in women who do not have hormone receptor positive breast cancer: because of the higher sensitivity induced by AI-co-therapy, FSH-doses and -costs for assisted reproduction are reduced, and ovarian hyperstimulation syndrome (OHSS may be avoided. For premenopausal diseases which are said to be positively affected by

  11. CHEMICAL CONTROL OF THE TOMATO LEAF MINER Scrobipalpuloides absoluta (MEYRICK USING A NEW INSETICIDE INHIBITOR OF ECDYSIS CONTROLE QUÍMICO DA Scrobipalpuloides absoluta Meyrick, 1971 SOBRE TOMATEIRO INDUSTRIAL COM INSETICIDA FISIOLÓGICO INIBIDOR DA ECDISE

    Directory of Open Access Journals (Sweden)

    Antônio Lopes da Silva

    2007-09-01

    Full Text Available

    The tomato leafminer (Scrobipalpuloides absoluta, a common pest of tomato plant, is distributed in many regions in Brazil. In order to determine the efficiency of Chlorfluazuron to control the tomato leafminer, a field experiment was carried out in Goiânia, Goiás state, Brazil. The treatment and dosage in grams of active ingredient per hectare were: Chlorfluazuron 50 EC (25,35.5,50 and 75; Abamectin 18 EC (18; Cartap 500 BR (480 and an untreated check. The results of the experiment showed that Chlorfluazuron at dosages of 37.5, 50 and 75 g i.a./ha was efficient in controlling the tomato leafminer. It was similar to the results of abamectin and cartap at the dosages utilized.

    KEY-WORDS: Scrobipalpuloides absoluta; tomato plants; chemical control.

    Foi realizado, no município de Goiânia (GO, no período de maio a outubro de 1994, um experimento visando ao controle químico da traça (S. absoluta no tomateiro, cultura rasteira. O delineamento experimental foi de blocos ao acaso com sete tratamentos em quatro repetições. Cada unidade experimental foi constituída de quatro linhas com cinco metros de comprimento, um metro entre linhas da cultivar Roma VF. Os produtos utilizados foram: Atabron 50 CE (Clorfluazuron nas doses de 0,5; 0,75; 1,0 e 1,5 litro por hectare do produto comercial; Vertimec 18 CE (Abamectin: 1,0 litro por hectare, acrescido de 0,25% de óleo mineral; Cartap 500 BR (Cartap na dose de 0,96 kg/hectare; e uma testemunha. Foram realizadas quatro aplicações consecutivas, semanalmente, a partir do aparecimento dos primeiros adultos da praga na cultura, gastando-se 1.000 litros de

  12. Towards isozyme-selective HDAC inhibitors for interrogating disease.

    Science.gov (United States)

    Gupta, Praveer; Reid, Robert C; Iyer, Abishek; Sweet, Matthew J; Fairlie, David P

    2012-01-01

    Histone deacetylase (HDAC) enzymes have emerged as promising targets for the treatment of a wide range of human diseases, including cancers, inflammatory and metabolic disorders, immunological, cardiovascular, and infectious diseases. At present, such applications are limited by the lack of selective inhibitors available for each of the eighteen HDAC enzymes, with most currently available HDAC inhibitors having broad-spectrum activity against multiple HDAC enzymes. Such broad-spectrum activity maybe useful in treating some diseases like cancers, but can be detrimental due to cytotoxic side effects that accompany prolonged treatment of chronic diseased states. Here we summarize progress towards the design and discovery of HDAC inhibitors that are selective for some of the eleven zinc-containing classical HDAC enzymes, and identify opportunities to use such isozyme-selective inhibitors as chemical probes for interrogating the biological roles of individual HDAC enzymes in diseases.

  13. Effect of inhibitors on macroscopical oxidation kinetics of calcium sulfite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi; WANG Li-dong; WANG Xiao-ming; LI Qiang-wei; XU Pei-yao

    2005-01-01

    In the presence of inhibitors, the macroscopical oxidation kinetics of calcium sulfite, the main byproduct in wet limestone scrubbing, was studied for the first time by adding different inhibitors and varying pH, concentration of calcium sulfite, oxygen partial pressure, concentration of inhibitors and temperature. The mathematical model about the general oxidation reaction was established,which was controlled by three steps involving dissolution of calcium sulfite, mass transfer of oxygen and chemical reaction in the solution.It was concluded that the general reaction was controlled by mass transfer of oxygen under uncatalyzed conditions, while it was controlled by dissolution of calcium sulfite after adding three kinds of inhibitors. Thus, the theory was provided for investigating the mechanism and oxidation kinetics of sulfite. The beneficial references were also supplied for design of oxidation technics in the wet limestone scrubbing.

  14. Electrochemical Evaluation of Corrosion Inhibitors to Austenistic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Yosmari Adames Montero

    2014-03-01

    Full Text Available The use of corrosion inhibitors is one of the most universal methods, and diffused for the protection ofmetals, because they reduce substantially the corrosion losses when they are added in smallconcentrations. At the present work it was carried out the electrochemical tests evaluation of twoinhibitors, A and B, to be used in the chemical cleanings for trays of heat interchanger, which aresuffering thickness losses until its perforation. By the chemical composition analysis, it wasdemonstrated that the metal is an austenistic stainless steel and by electrochemical tests of linearpolarization resistance, electrochemical noise and cyclic sweep, were demonstrated the localizedcorrosion. The best efficiency of the inhibitor A was obtained with one and two percent concentration,while the inhibitor B shows values efficiency near 95% with two percent concentration.

  15. Modified 5-fluorouracil: Uridine phosphorylase inhibitor

    Science.gov (United States)

    Lashkov, A. A.; Shchekotikhin, A. A.; Shtil, A. A.; Sotnichenko, S. E.; Mikhailov, A. M.

    2016-09-01

    5-Fluorouracil (5-FU) is a medication widely used in chemotherapy to treat various types of cancer. Being a substrate for the reverse reaction catalyzed by uridine phosphorylase (UPase), 5-FU serves as a promising prototype molecule (molecular scaffold) for the design of a selective UPase inhibitor that enhances the antitumor activity of 5-FU and exhibits intrinsic cytostatic effects on cancer cells. The chemical formula of the new compound, which binds to the uracil-binding site and, in the presence of a phosphate anion, to the phosphate-binding site of UPase, is proposed and investigated by molecular simulation methods.

  16. Protein kinase CK2 inhibition is associated with the destabilization of HIF-1α in human cancer cells

    DEFF Research Database (Denmark)

    Guerra, Barbara; Rasmussen, Tine D. L.; Schnitzler, Alexander

    2015-01-01

    Screening for protein kinase CK2 inhibitors of the structural diversity compound library (DTP NCI/NIH) led to the discovery of 4-[(E)-(fluoren-9-ylidenehydrazinylidene)-methyl]benzoic acid (E9). E9 induces apoptotic cell death in various cancer cell lines and upon hypoxia, the compound suppresses...... CK2-catalyzed HSP90/Cdc37 phosphorylation and induces HIF-1alpha degradation. Furthermore, E9 exerts a strong anti-tumour activity by inducing necrosis in murine xenograft models underlining its potential to be used for cancer treatment in future clinical studies. Crystal structure analysis of human...

  17. Benzotriazole a Corrosion Inhibitor for Antiques: Some Practical Surface Chemistry.

    Science.gov (United States)

    Walker, Robert

    1980-01-01

    Describes the structure and inhibitive properties of Benzotriazole. The chemical may be employed as an inhibitor to reduce corrosion of articles during storage or display. It may be applied to copper and copper-based antiques as well as to silver and other metals. (Author/JN)

  18. Chemical use

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of research and activities related to chemical use on Neal Smith National Wildlife Refuge between 1992 and 2009. The chemicals used on the Refuge...

  19. Chemical Reactors.

    Science.gov (United States)

    Kenney, C. N.

    1980-01-01

    Describes a course, including content, reading list, and presentation on chemical reactors at Cambridge University, England. A brief comparison of chemical engineering education between the United States and England is also given. (JN)

  20. Designing Inhibitors of Anthrax Toxin

    Science.gov (United States)

    Nestorovich, Ekaterina M.; Bezrukov, Sergey M.

    2014-01-01

    Introduction Present-day rational drug design approaches are based on exploiting unique features of the target biomolecules, small- or macromolecule drug candidates, and physical forces that govern their interactions. The 2013 Nobel Prize in chemistry awarded “for the development of multiscale models for complex chemical systems” once again demonstrated the importance of the tailored drug discovery that reduces the role of the trial and error approach to a minimum. The “rational drug design” term is rather comprehensive as it includes all contemporary methods of drug discovery where serendipity and screening are substituted by the information-guided search for new and existing compounds. Successful implementation of these innovative drug discovery approaches is inevitably preceded by learning the physics, chemistry, and physiology of functioning of biological structures under normal and pathological conditions. Areas covered This article provides an overview of the recent rational drug design approaches to discover inhibitors of anthrax toxin. Some of the examples include small-molecule and peptide-based post-exposure therapeutic agents as well as several polyvalent compounds. The review also directs the reader to the vast literature on the recognized advances and future possibilities in the field. Expert opinion Existing options to combat anthrax toxin lethality are limited. With the only anthrax toxin inhibiting therapy (PA-targeting with a monoclonal antibody, raxibacumab) approved to treat inhalational anthrax, in our view, the situation is still insecure. The FDA’s animal rule for drug approval, which clears compounds without validated efficacy studies on humans, creates a high level of uncertainty, especially when a well-characterized animal model does not exist. Besides, unlike PA, which is known to be unstable, LF remains active in cells and in animal tissues for days. Therefore, the effectiveness of the post-exposure treatment of the individuals

  1. A reduced-amide inhibitor of Pin1 binds in a conformation resembling a twisted-amide transition state.

    Science.gov (United States)

    Xu, Guoyan G; Zhang, Yan; Mercedes-Camacho, Ana Y; Etzkorn, Felicia A

    2011-11-08

    The mechanism of the cell cycle regulatory peptidyl prolyl isomerase (PPIase), Pin1, was investigated using reduced-amide inhibitors designed to mimic the twisted-amide transition state. Inhibitors, R-pSer-Ψ[CH(2)N]-Pro-2-(indol-3-yl)ethylamine, 1 [R = fluorenylmethoxycarbonyl (Fmoc)] and 2 (R = Ac), of Pin1 were synthesized and bioassayed. Inhibitor 1 had an IC(50) value of 6.3 μM, which is 4.5-fold better for Pin1 than our comparable ground-state analogue, a cis-amide alkene isostere-containing inhibitor. The change of Fmoc to Ac in 2 improved aqueous solubility for structural determination and resulted in an IC(50) value of 12 μM. The X-ray structure of the complex of 2 bound to Pin1 was determined to 1.76 Å resolution. The structure revealed that the reduced amide adopted a conformation similar to the proposed twisted-amide transition state of Pin1, with a trans-pyrrolidine conformation of the prolyl ring. A similar conformation of substrate would be destabilized relative to the planar amide conformation. Three additional reduced amides, with Thr replacing Ser and l- or d-pipecolate (Pip) replacing Pro, were slightly weaker inhibitors of Pin1.

  2. Inhibitors of lysosomal cysteine proteases

    Directory of Open Access Journals (Sweden)

    Lyanna O. L.

    2011-04-01

    Full Text Available The review is devoted to the inhibitors of cysteine proteinases which are believed to be very important in many biochemical processes of living organisms. They participate in the development and progression of numerous diseases that involve abnormal protein turnover. One of the main regulators of these proteinases is their specific inhibitors: cystatins. The aim of this review was to present current knowledge about endogenous inhibitors of lysosomal cysteine proteases and their synthetic analogs.

  3. ACE INHIBITORS: A COMPREHENSIVE REVIEW

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Arora* and Ashish Chauhan

    2013-02-01

    Full Text Available Hypertension is a chronic increase in blood pressure, characterized as primary and secondary hypertension. The disorder is associated with various risk factors like obesity, diabetes, age, lack of exercise etc. Hypertension is being treated since ancient times by Ayurvedic, Chinese and Unani medicine. Now various allopathic drugs are available which include diuretics, calcium channel blockers, α-blockers, β-blockers, vasodilators, central sympatholytics and ACE-inhibitors. Non-pharmacological treatments include weight reduction, dietary sodium reduction, increased potassium intake and reduction in alcohol consumption. ACE-inhibitors are widely used in the treatment of hypertension by inhibiting the angiotensin converting enzyme responsible for the conversion of angiotensin I to angiotensin II (responsible for vasoconstriction. Various structure activity relationship studies led to the synthesis of ACE-inhibitors, some are under clinical development. This comprehensive review gives various guidelines on classification of hypertension, hypertension therapy including ancient, pharmacological, non-pharmacological therapies, pharmacoeconomics, historical perspectives of ACE, renin, renin angiotensin system (circulating vs local RAS, mechanism of ACE inhibitors, and development of ACE inhibitors. Review also emphasizes on the recent advancements on ACE inhibitors including drugs in clinical trials, computational studies on ACE-inhibitors, peptidomimetics, dual, natural, multi-functional ACE inhibitors, and conformational requirements for ACE-inhibitors.

  4. Inhibitor Ranking Through QM based Chelation Calculations for Virtual Screening of HIV-1 RNase H inhibition

    DEFF Research Database (Denmark)

    Poongavanam, Vasanthanathan; Svendsen, Casper Steinmann; Kongsted, Jacob

    2014-01-01

    . Furthermore, full protein fragment molecular orbital (FMO) calculations were conducted and subsequently analysed for individual residue stabilization/destabilization energy contributions to the overall binding affinity in order to better understand the true and false predictions. After a successful assessment......Quantum mechanical (QM) calculations have been used to predict the binding affinity of a set of ligands towards HIV-1 RT associated RNase H (RNH). The QM based chelation calculations show improved binding affinity prediction for the inhibitors compared to using an empirical scoring function...... of the methods based on the use of a training set of molecules, QM based chelation calculations were used as filter in virtual screening of compounds in the ZINC database. By this, we find, compared to regular docking, QM based chelation calculations to significantly reduce the large number of false positives...

  5. Corrosion protection with eco-friendly inhibitors

    Science.gov (United States)

    Shahid, Muhammad

    2011-12-01

    Corrosion occurs as a result of the interaction of a metal with its environment. The extent of corrosion depends on the type of metal, the existing conditions in the environment and the type of aggressive ions present in the medium. For example, CO3-2 and NO-3 produce an insoluble deposit on the surface of iron, resulting in the isolation of metal and consequent decrease of corrosion. On the other hand, halide ions are adsorbed selectively on the metal surface and prevent formation of the oxide phase on the metal surface, resulting in continuous corrosion. Iron, aluminum and their alloys are widely used, both domestically and industrially. Linear alkylbenzene and linear alkylbenzene sulfonate are commonly used as detergents. They have also been found together in waste water. It is claimed that these chemicals act as inhibitors for stainless steel and aluminum. Release of toxic gases as a result of corrosion in pipelines may lead in certain cases to air pollution and possible health hazards. Therefore, there are two ways to look at the relationship between corrosion and pollution: (i) corrosion of metals and alloys due to environmental pollution and (ii) environmental pollution as a result of corrosion protection. This paper encompasses the two scenarios and possible remedies for various cases, using 'green' inhibitors obtained either from plant extracts or from pharmaceutical compounds. In the present study, the effect of piperacillin sodium as a corrosion inhibitor for mild steel was investigated using a weight-loss method as well as a three-electrode dc electrochemical technique. It was found that the corrosion rate decreased as the concentration of the inhibitor increased up to 9×10-4 M 93% efficiency was exhibited at this concentration.

  6. Nanomolar Inhibitors of Trypanosoma brucei RNA Triphosphatase

    Directory of Open Access Journals (Sweden)

    Paul Smith

    2016-02-01

    Full Text Available Eukaryal taxa differ with respect to the structure and mechanism of the RNA triphosphatase (RTPase component of the mRNA capping apparatus. Protozoa, fungi, and certain DNA viruses have a metal-dependent RTPase that belongs to the triphosphate tunnel metalloenzyme (TTM superfamily. Because the structures, active sites, and chemical mechanisms of the TTM-type RTPases differ from those of mammalian RTPases, the TTM RTPases are potential targets for antiprotozoal, antifungal, and antiviral drug discovery. Here, we employed RNA interference (RNAi knockdown methods to show that Trypanosoma brucei RTPase Cet1 (TbCet1 is necessary for proliferation of procyclic cells in culture. We then conducted a high-throughput biochemical screen for small-molecule inhibitors of the phosphohydrolase activity of TbCet1. We identified several classes of chemicals—including chlorogenic acids, phenolic glycopyranosides, flavonoids, and other phenolics—that inhibit TbCet1 with nanomolar to low-micromolar 50% inhibitory concentrations (IC50s. We confirmed the activity of these compounds, and tested various analogs thereof, by direct manual assays of TbCet1 phosphohydrolase activity. The most potent nanomolar inhibitors included tetracaffeoylquinic acid, 5-galloylgalloylquinic acid, pentagalloylglucose, rosmarinic acid, and miquelianin. TbCet1 inhibitors were less active (or inactive against the orthologous TTM-type RTPases of mimivirus, baculovirus, and budding yeast (Saccharomyces cerevisiae. Our results affirm that a TTM RTPase is subject to potent inhibition by small molecules, with the caveat that parallel screens against TTM RTPases from multiple different pathogens may be required to fully probe the chemical space of TTM inhibition.

  7. Genomic analysis suggests that mRNA destabilization by the microprocessor is specialized for the auto-regulation of Dgcr8.

    Directory of Open Access Journals (Sweden)

    Archana Shenoy

    Full Text Available BACKGROUND: The Microprocessor, containing the RNA binding protein Dgcr8 and RNase III enzyme Drosha, is responsible for processing primary microRNAs to precursor microRNAs. The Microprocessor regulates its own levels by cleaving hairpins in the 5'UTR and coding region of the Dgcr8 mRNA, thereby destabilizing the mature transcript. METHODOLOGY/PRINCIPAL FINDINGS: To determine whether the Microprocessor has a broader role in directly regulating other coding mRNA levels, we integrated results from expression profiling and ultra high-throughput deep sequencing of small RNAs. Expression analysis of mRNAs in wild-type, Dgcr8 knockout, and Dicer knockout mouse embryonic stem (ES cells uncovered mRNAs that were specifically upregulated in the Dgcr8 null background. A number of these transcripts had evolutionarily conserved predicted hairpin targets for the Microprocessor. However, analysis of deep sequencing data of 18 to 200nt small RNAs in mouse ES, HeLa, and HepG2 indicates that exonic sequence reads that map in a pattern consistent with Microprocessor activity are unique to Dgcr8. CONCLUSION/SIGNIFICANCE: We conclude that the Microprocessor's role in directly destabilizing coding mRNAs is likely specifically targeted to Dgcr8 itself, suggesting a specialized cellular mechanism for gene auto-regulation.

  8. Relative contribution of structural inheritance and glacial morphology on the post-glacial slope destabilization. The Séchilienne slope case study (French western Alps).

    Science.gov (United States)

    Schwartz, Stéphane; Zerathe, Swann; Audin, Laurence; Dumont, Thierry; Jarre, Raphael; Jongmans, Denis; Carcaillet, Julien; Dubois, Laurent

    2016-04-01

    In the main Alpine valleys, the chronological constraints about the onset of the slope movements following glacial retreat are scarse. The southern part of the Belledonne massif (French western Alps) along the Romanche valley is affected by numerous slope destabilizations. A detailed geomorphological study using a high resolution LIDAR digital model elevation, allows to characterize the structural framework, the evolution of the glacial retreat and the distribution of the gravitational instabilities. The systematic survey of (i) the main fracturing and (ii) the glacial and gravity morphological witness along the slopes of the Romanche valley coupled with (iii) cosmogenic 10Be dating provides a regional view of the dynamics of slope destabilisation in this area. The proposed scenario allows to evaluate the relative influence of different triggering factors such as seismo-tectonic stresses and climatic changes. These data also allow to propose a consistent dynamic destabilization model of a major lanslide (> 100×106 m3) in relation with the last episode of glacial retreat ~ 21ka ago.

  9. Task Repetition and Noticing as a Route to Semester-long Destabilization: A Cross-sectional Study of Iranian EFL Learners’ Oral Output

    Directory of Open Access Journals (Sweden)

    Ali Eliasi

    2013-05-01

    Full Text Available Tackling learners’ erroneous oral output has always been a substantial issue for both language teachers and researchers. Taking Swain’s output hypothesis and Schmidt’s noticing hypothesis into account, this study aims at investigating the effect of task- initiated noticing along with task repetition sessions as a route to destabilization of learner errors. The participants of the study were thirty two Iranian upper-intermediate learners.  The participants were divided into two groups, an experimental and a control group.  Both groups’ voices were recorded while delivering a prepared speech. The participants in experimental group were given the recorded presentation to be transcribed and compared with the original text they used while the control group didn’t receive feedback of any kind. The experimental group submitted a draft to their teacher who checked the papers and later asked them to prepare themselves for another prepared speech in the future. There was a pre-test, a treatment and a post-test. The comparison of the erroneous utterances in both groups lent support to the effectiveness of task repetition and noticing on destabilization of learners’ oral output. Keywords: fossilization, noticing, task repetition, output

  10. Chemoproteomics-Enabled Discovery of a Potent and Selective Inhibitor of the DNA Repair Protein MGMT.

    Science.gov (United States)

    Wang, Chao; Abegg, Daniel; Hoch, Dominic G; Adibekian, Alexander

    2016-02-18

    We present a novel chemical scaffold for cysteine-reactive covalent inhibitors. Chloromethyl triazoles (CMTs) are readily accessed in only two chemical steps, thus enabling the rapid optimization of the pharmacological properties of these inhibitors. We demonstrate the tunability of the CMTs towards a specific biological target by synthesizing AA-CW236 as the first potent non-pseudosubstrate inhibitor of the O(6) -alkylguanine DNA methyltransferase (MGMT), a protein of major clinical significance for the treatment of several severe cancer forms. Using quantitative proteomics profiling techniques, we show that AA-CW236 exhibits a high degree of selectivity towards MGMT. Finally, we validate the effectiveness of our MGMT inhibitor in combination with the DNA alkylating drug temozolomide in breast and colon cancer cells by fluorescence imaging and a cell-viability assay. Our results may open a new avenue towards the development of a clinically approved MGMT inhibitor.

  11. The Azadirachtins: potent insect growth inhibitors

    Directory of Open Access Journals (Sweden)

    Heinz Rembold

    1987-01-01

    Full Text Available In the course of their coevolution with insects, plants have learnt to protect themselves by chemical means. Semiochemical act as antifeedants or deterrents, others by disrupting growth and development. By use of the Epilachna varivestis bioassay we isolated from Azadirachta indica seed a group of triterpenoids which interfee with larval growth and development in ppm range. Main components are the azadirachtins A and B with identical biological activity. Various other azadirachtins were obtained, either as minor seed components or by chemical modification of the naturally occuring compounds. Structure vs. activity relation studies enabled us to postulate a basic structural element that should still be biologically active and with much simpler chemical structure than natural compounds. What underlies the biological activity of these insect growth inhibitors? Their interference with the hormonal regulation of development and reproduction has been studied in Locusta migratoria and Rhodnius prolixus. In addition, tritiated dihydroazadirachtin A was used. With this approach, a precise correlation between administered dose, resulting effects, and retention of the compound was established. The azadirachtins either interrupt, delay, or deviate whole developmental programs. Results from these studies provide another chemical probe for studies in insect endocrinology and physiology.

  12. Green chemistry applied to corrosion and scale inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Darling, D.; Rakshpal, R. [Environmental Protection Agency, Washington, DC (United States)

    1998-12-31

    Numerous breakthroughs in environmental protection and pollution prevention have been realized in recent years by both industry and academia through the application of green chemistry principles. Green chemistry, or pollution prevention at the molecular level, is chemistry designed to reduce or eliminate the use or generation of hazardous materials associated with the manufacture and application of chemicals. The application of the green chemistry principles to the areas of corrosion and scale inhibitors has resulted in the reduction/elimination of many of the more toxic inhibitors and the development of newer, more environmentally friendly ones.

  13. Acetylcholinesterase Inhibitors: Pharmacology and Toxicology

    OpenAIRE

    Čolović, Mirjana B.; Krstić, Danijela Z; Lazarević-Pašti, Tamara D; Bondžić, Aleksandra M; Vasić, Vesna M

    2013-01-01

    Acetylcholinesterase is involved in the termination of impulse transmission by rapid hydrolysis of the neurotransmitter acetylcholine in numerous cholinergic pathways in the central and peripheral nervous systems. The enzyme inactivation, induced by various inhibitors, leads to acetylcholine accumulation, hyperstimulation of nicotinic and muscarinic receptors, and disrupted neurotransmission. Hence, acetylcholinesterase inhibitors, interacting with the enzyme as their primary target, are appl...

  14. Proteinaceous alpha-araylase inhibitors

    DEFF Research Database (Denmark)

    Svensson, Birte; Fukuda, Kenji; Nielsen, P.K.;

    2004-01-01

    Proteins that inhibit alpha-amylases have been isolated from plants and microorganisms. These inhibitors can have natural roles in the control of endogenous a-amylase activity or in defence against pathogens and pests; certain inhibitors are reported to be antinutritional factors. The alpha-amylase...... inhibitors belong to seven different protein structural families, most of which also contain evolutionary related proteins without inhibitory activity. Two families include bifunctional inhibitors acting both on alpha-amylases and proteases. High-resolution structures are available of target alpha-amylases...... in complex with inhibitors from five families. These structures indicate major diversity but also some similarity in the structural basis of alpha-amylase inhibition. Mutational analysis of the mechanism of inhibition was performed in a few cases and various protein engineering and biotechnological...

  15. Proteinase inhibitors in Brazilian leguminosae

    Directory of Open Access Journals (Sweden)

    C. A. M. Sampaio

    1991-01-01

    Full Text Available Serine proteinase inhitors, in the seeds of several Leguminosae from the Pantanal region (West Brazil, were studied using bovine trypsin, a digestive enzyme, Factor XIIa and human plasma Kallikrein, two blood clotting factors. The inhibitors were purified from Enterolobium contortisiliquum (Mr=23,000, Torresea cearensis (Mr = 13,000, Bauhinia pentandra (Mr = 20,000 and Bauhinia bauhinioides (Mr = 20,000. E. contortisiliquum inhibitor inactivates all three enzymes, whereas the T. cearensis inhibitor inactivates trypsin and Factor XSSa, but does nor affect plasma kallikrein; both Bauhinia inhibitors, on the other hand, inactivate trypsin and plasma kallikrein but only the Bpentandra inhibitor affects Factor XIIa. Ki values were calculated between 10 [raised to the power of] -7 and 10 [raised to the power of] -8 M.

  16. Identifying tumor cell growth inhibitors by combinatorial chemistry and zebrafish assays.

    Directory of Open Access Journals (Sweden)

    Jing Xiang

    Full Text Available Cyclin-dependent kinases (CDKs play important roles in regulating cell cycle progression, and altered cell cycles resulting from over-expression or abnormal activation of CDKs observed in many human cancers. As a result, CDKs have become extensive studied targets for developing chemical inhibitors for cancer therapies; however, protein kinases share a highly conserved ATP binding pocket at which most chemical inhibitors bind, therefore, a major challenge in developing kinase inhibitors is achieving target selectivity. To identify cell growth inhibitors with potential applications in cancer therapy, we used an integrated approach that combines one-pot chemical synthesis in a combinatorial manner to generate diversified small molecules with new chemical scaffolds coupled with growth inhibition assay using developing zebrafish embryos. We report the successful identification of a novel lead compound that displays selective inhibitory effects on CDK2 activity, cancer cell proliferation, and tumor progression in vivo. Our approaches should have general applications in developing cell proliferation inhibitors using an efficient combinatorial chemical genetic method and integrated biological assays. The novel cell growth inhibitor we identified should have potential as a cancer therapeutic agent.

  17. Effect of Wall Shear Stress on Corrosion Inhibitor Film Performance

    Science.gov (United States)

    Canto Maya, Christian M.

    In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO 2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibitor

  18. Chemical sensors

    Science.gov (United States)

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  19. Transforming growth factor-β3 regulates cell junction restructuring via MAPK-mediated mRNA destabilization and Smad-dependent protein degradation of junctional adhesion molecule B (JAM-B).

    Science.gov (United States)

    Zhang, Xu; Lui, Wing-Yee

    2015-06-01

    Junctional adhesion molecule-B (JAM-B) is found between Sertoli cells at the blood-testis barrier (BTB) as well as between Sertoli and germ cells at the apical ectoplasmic specializations (ES) in the testis. The expression of JAM-B is tightly regulated to modulate the passage of spermatocytes across the BTB as well as the release of mature spermatozoa from the seminiferous epithelium. Transforming growth factor beta (TGF-β) family is implicated in the regulation of testicular cell junction dynamics during spermatogenesis. This study aims to investigate the effects of TGF-β3 on the expression of JAM-B as well as the underlying mechanisms on how TGF-β3 regulates JAM-B expression to facilitate the disassembly of the BTB and apical ES. Our results revealed that TGF-β3 suppresses JAM-B at post-transcriptional and post-translational levels. Inhibitor, siRNA knockdown and co-immunoprecipitation have shown that TGF-β3 induces JAM-B protein degradation via ubiquitin-proteasome pathway. Immunofluorescence staining further confirmed that blockage of ubiquitin-proteasome pathway could abrogate TGF-β3-induced loss of JAM-B at the cell-cell interface. siRNA knockdown and immunofluorescence staining also demonstrated that activation of Smad signaling is required for TGF-β3-induced JAM-B protein degradation. In addition, TGF-β3 reduces JAM-B mRNA levels, at least in part, via post-transcriptional regulation. mRNA stability assay has confirmed that TGF-β3 promotes the degradation of JAM-B transcript and TGF-β3-mediated mRNA destabilization requires the activation of ERK1/2 and p54 JNK signal cascades. Taken together, TGF-β3 significantly downregulates JAM-B expression via post-transcriptional and post-translational modulation and results in the disruption of BTB and apical ES.

  20. Chemical compound navigator: a web-based chem-BLAST, chemical taxonomy-based search engine for browsing compounds.

    Science.gov (United States)

    Prasanna, M D; Vondrasek, Jiri; Wlodawer, Alexander; Rodriguez, H; Bhat, T N

    2006-06-01

    A novel technique to annotate, query, and analyze chemical compounds has been developed and is illustrated by using the inhibitor data on HIV protease-inhibitor complexes. In this method, all chemical compounds are annotated in terms of standard chemical structural fragments. These standard fragments are defined by using criteria, such as chemical classification; structural, chemical, or functional groups; and commercial, scientific or common names or synonyms. These fragments are then organized into a data tree based on their chemical substructures. Search engines have been developed to use this data tree to enable query on inhibitors of HIV protease (http://xpdb.nist.gov/hivsdb/hivsdb.html). These search engines use a new novel technique, Chemical Block Layered Alignment of Substructure Technique (Chem-BLAST) to search on the fragments of an inhibitor to look for its chemical structural neighbors. This novel technique to annotate and query compounds lays the foundation for the use of the Semantic Web concept on chemical compounds to allow end users to group, sort, and search structural neighbors accurately and efficiently. During annotation, it enables the attachment of "meaning" (i.e., semantics) to data in a manner that far exceeds the current practice of associating "metadata" with data by creating a knowledge base (or ontology) associated with compounds. Intended users of the technique are the research community and pharmaceutical industry, for which it will provide a new tool to better identify novel chemical structural neighbors to aid drug discovery.

  1. Rational design of Rho GTPase-targeting inhibitors.

    Science.gov (United States)

    Shang, Xun; Zheng, Yi

    2012-01-01

    Rho GTPases have been implicated in diverse cellular functions and are potential therapeutic targets in inflammation, cancer, and neurologic diseases. Virtual screening of compounds that fit into surface grooves of RhoA known to be critical for guanine nucleotide exchange factor (GEF) interaction produced chemical candidates with minimized docking energy. Subsequent screening for inhibitory activity of RhoA binding to the Rho-GEF, LARG, identified a Rho-specific inhibitor as a lead compound capable of blocking RhoA-LARG interaction and RhoA activation by LARG specifically and dose dependently. A microscale thermophoresis analysis was applied to directly quantify the binding interaction of the lead inhibitor with RhoA target. The lead inhibitor highlights the principle that rational targeting of subfamily members of Rho GTPases is feasible and potentially useful in future drug design effort.

  2. A Pan-GTPase Inhibitor as a Molecular Probe.

    Directory of Open Access Journals (Sweden)

    Lin Hong

    Full Text Available Overactive GTPases have often been linked to human diseases. The available inhibitors are limited and have not progressed far in clinical trials. We report here a first-in-class small molecule pan-GTPase inhibitor discovered from a high throughput screening campaign. The compound CID1067700 inhibits multiple GTPases in biochemical, cellular protein and protein interaction, as well as cellular functional assays. In the biochemical and protein interaction assays, representative GTPases from Rho, Ras, and Rab, the three most generic subfamilies of the GTPases, were probed, while in the functional assays, physiological processes regulated by each of the three subfamilies of the GTPases were examined. The chemical functionalities essential for the activity of the compound were identified through structural derivatization. The compound is validated as a useful molecular probe upon which GTPase-targeting inhibitors with drug potentials might be developed.

  3. A Pan-GTPase Inhibitor as a Molecular Probe.

    Science.gov (United States)

    Hong, Lin; Guo, Yuna; BasuRay, Soumik; Agola, Jacob O; Romero, Elsa; Simpson, Denise S; Schroeder, Chad E; Simons, Peter; Waller, Anna; Garcia, Matthew; Carter, Mark; Ursu, Oleg; Gouveia, Kristine; Golden, Jennifer E; Aubé, Jeffrey; Wandinger-Ness, Angela; Sklar, Larry A

    2015-01-01

    Overactive GTPases have often been linked to human diseases. The available inhibitors are limited and have not progressed far in clinical trials. We report here a first-in-class small molecule pan-GTPase inhibitor discovered from a high throughput screening campaign. The compound CID1067700 inhibits multiple GTPases in biochemical, cellular protein and protein interaction, as well as cellular functional assays. In the biochemical and protein interaction assays, representative GTPases from Rho, Ras, and Rab, the three most generic subfamilies of the GTPases, were probed, while in the functional assays, physiological processes regulated by each of the three subfamilies of the GTPases were examined. The chemical functionalities essential for the activity of the compound were identified through structural derivatization. The compound is validated as a useful molecular probe upon which GTPase-targeting inhibitors with drug potentials might be developed.

  4. Current topics on inhibitors of respiratory complex I.

    Science.gov (United States)

    Murai, Masatoshi; Miyoshi, Hideto

    2016-07-01

    There are a variety of chemicals which regulate the functions of bacterial and mitochondrial complex I. Some of them, such as rotenone and piericidin A, have been indispensable molecular tools in mechanistic studies on complex I. A large amount of experimental data characterizing the actions of complex I inhibitors has been accumulated so far. Recent X-ray crystallographic structural models of entire complex I may be helpful to carefully interpret this data. We herein focused on recent hot topics on complex I inhibitors and the subjects closely connected to these inhibitors, which may provide useful information not only on the structural and functional aspects of complex I, but also on drug design targeting this enzyme. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.

  5. Natural product Celastrol destabilizes tubulin heterodimer and facilitates mitotic cell death triggered by microtubule-targeting anti-cancer drugs.

    Directory of Open Access Journals (Sweden)

    Hakryul Jo

    Full Text Available BACKGROUND: Microtubule drugs are effective anti-cancer agents, primarily due to their ability to induce mitotic arrest and subsequent cell death. However, some cancer cells are intrinsically resistant or acquire a resistance. Lack of apoptosis following mitotic arrest is thought to contribute to drug resistance that limits the efficacy of the microtubule-targeting anti-cancer drugs. Genetic or pharmacological agents that selectively facilitate the apoptosis of mitotic arrested cells present opportunities to strengthen the therapeutic efficacy. METHODOLOGY AND PRINCIPAL FINDINGS: We report a natural product Celastrol targets tubulin and facilitates mitotic cell death caused by microtubule drugs. First, in a small molecule screening effort, we identify Celastrol as an inhibitor of neutrophil chemotaxis. Subsequent time-lapse imaging analyses reveal that inhibition of microtubule-mediated cellular processes, including cell migration and mitotic chromosome alignment, is the earliest events affected by Celastrol. Disorganization, not depolymerization, of mitotic spindles appears responsible for mitotic defects. Celastrol directly affects the biochemical properties of tubulin heterodimer in vitro and reduces its protein level in vivo. At the cellular level, Celastrol induces a synergistic apoptosis when combined with conventional microtubule-targeting drugs and manifests an efficacy toward Taxol-resistant cancer cells. Finally, by time-lapse imaging and tracking of microtubule drug-treated cells, we show that Celastrol preferentially induces apoptosis of mitotic arrested cells in a caspase-dependent manner. This selective effect is not due to inhibition of general cell survival pathways or mitotic kinases that have been shown to enhance microtubule drug-induced cell death. CONCLUSIONS AND SIGNIFICANCE: We provide evidence for new cellular pathways that, when perturbed, selectively induce the apoptosis of mitotic arrested cancer cells, identifying a

  6. Chemical intolerance

    DEFF Research Database (Denmark)

    Dantoft, Thomas Meinertz; Andersson, Linus; Nordin, Steven;

    2015-01-01

    Chemical intolerance (CI) is a term used to describe a condition in which the sufferer experiences a complex array of recurrent unspecific symptoms attributed to low-level chemical exposure that most people regard as unproblematic. Severe CI constitutes the distinguishing feature of multiple...... chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI...

  7. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  8. Destabilization emulsion of oil by means of additives based on silicones polyethers; Desestabilizacao de emulsoes de petroleo por meio de aditivos a base de silicones polieteres

    Energy Technology Data Exchange (ETDEWEB)

    Jarque, Erika A.; Mansur, Claudia R.E. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano], e-mails: alegrio@ima.ufrj.br, celias@ima.ufrj.br

    2011-07-01

    The process of demulsification has great importance in the petroleum industry, since the formation of emulsions is a natural phenomenon in this sector. Several polymers have been used commercially as additives emulsion destabilizing, among them are the block copolymers of poly (ethylene oxide)-poly (propylene oxide) (PEO-PPO). This work aims to study the efficiency of five additives based on silicones polyethers, which have structures in their chains of poly (ethylene oxide) (PEO) or PEO-PPO copolymers. The results show that the addition of these additives in the water / oil reduced the values of interfacial tension of systems. From the testing of gravitational separation water / oil was observed that all the additives promoted the breakdown of water / oil, but those who hold in their structures the chains of block copolymers of PEO-PPO were the most efficient, and that the caused a smaller reduction in the interfacial tensions of these systems. (author)

  9. Gravity destabilized non-wetting phase invasion in macro-heterogeneous porous media: Near pore scale macro modified invasion percolation simulation of experiments

    Energy Technology Data Exchange (ETDEWEB)

    GLASS JR.,ROBERT J.; CONRAD,STEPHEN H.; YARRINGTON,LANE

    2000-03-08

    The authors reconceptualize macro modified invasion percolation (MMIP) at the near pore (NP) scale and apply it to simulate the non-wetting phase invasion experiments of Glass et al [in review] conducted in macro-heterogeneous porous media. For experiments where viscous forces were non-negligible, they redefine the total pore filling pressure to include viscous losses within the invading phase as well as the viscous influence to decrease randomness imposed by capillary forces at the front. NP-MMIP exhibits the complex invasion order seen experimentally with characteristic alternations between periods of gravity stabilized and destabilized invasion growth controlled by capillary barriers. The breaching of these barriers and subsequent pore scale fingering of the non-wetting phase is represented extremely well as is the saturation field evolution, and total volume invaded.

  10. Structures of Highly Twisted Amides Relevant to Amide N-C Cross-Coupling: Evidence for Ground-State Amide Destabilization.

    Science.gov (United States)

    Pace, Vittorio; Holzer, Wolfgang; Meng, Guangrong; Shi, Shicheng; Lalancette, Roger; Szostak, Roman; Szostak, Michal

    2016-10-04

    Herein, we show that acyclic amides that have recently enabled a series of elusive transition-metal-catalyzed N-C activation/cross-coupling reactions are highly twisted around the N-C(O) axis by a new destabilization mechanism of the amide bond. A unique effect of the N-glutarimide substituent, leading to uniformly high twist (ca. 90°) irrespective of the steric effect at the carbon side of the amide bond has been found. This represents the first example of a twisted amide that does not bear significant steric hindrance at the α-carbon atom. The (15) N NMR data show linear correlations between electron density at nitrogen and amide bond twist. This study strongly supports the concept of amide bond ground-state twist as a blueprint for activation of amides toward N-C bond cleavage. The new mechanism offers considerable opportunities for organic synthesis and biological processes involving non-planar amide bonds.

  11. Methane release from the East-Siberian Arctic Shelf and its connection with permafrost and hydrate destabilization: First results and potential future developments

    Science.gov (United States)

    Shakhova, N.; Semiletov, I.

    2012-04-01

    The East Siberian Arctic Shelf (ESAS) is home to the world's largest hydrocarbon stocks, which consist of natural gas, coal bed methane (CH4), and shallow Arctic hydrates. Until recently, the ESAS was not considered a CH4 source due to the supposed impermeability of sub-sea permafrost, which was thought to completely isolate the CH4 beneath from modern biogeochemical cycles. However, the ESAS represents an enormous potential CH4 source that could be responsive to ongoing global warming. Such response could occur in substantially shorter time than that of terrestrial Arctic ecosystems, because sub-sea permafrost has experienced long-lasting destabilization initiated by its inundation during the Holocene ocean transgression. ESAS permafrost stability and integrity is key to whether sequestered ancient carbon escapes as the potent greenhouse gas CH4. Recent data suggest the sub-sea permafrost is currently experiencing significant changes in its thermal regime. For example, our recent data obtained in the ESAS during the drilling expedition of 2011 showed no frozen sediments at all within the 53 m long drilling core at water temperatures varying from -0.6°C to -1.3°C. Unfrozen sediments provide multiple potential CH4 migration pathways. We suggest that open taliks have formed beneath the areas underlain or influenced by the nearby occurrence of fault zones, under paleo-valleys, and beneath thaw lakes submerged several thousand years ago during the ocean transgression. Temporary gas migration pathways might occur subsequent to seismic and tectonic activity in an area, due to sediment settlement and subsidence; hydrates could destabilize due to development of thermokarst-related features or ice-scouring. Recently obtained geophysical data identified numerous gas seeps, mostly above prominent reflectors, and the ubiquitous occurrence of shallow gas-charged sediments containing numerous gas chimneys, underscoring the likelihood that the ability of sub-sea permafrost to

  12. Effects of Ti-Based Additives on the Hydrogen Storage Properties of a LiBH4/CaH2 Destabilized System

    Directory of Open Access Journals (Sweden)

    Hongwei Yang

    2010-01-01

    Full Text Available The hydrogen storage properties of a destabilized LiBH4/CaH2 system ball-milled with TiCl3, TiF3, and TiO2 additives have been investigated. It is found that the system with TiCl3 additive has a lower dehydrogenation temperature than the ones with other additives. Further study shows that a higher amount of TiCl3 is more effective in reducing the desorption temperature of the LiBH4/CaH2 system, since it leads to a lower activation energy of dehydrogenation. The activations energies for mixtures containing 4, 10, and 25 mol% of TiCl3 are 141, 126, and 110 kJ/mol, respectively. However, the benefits of higher amounts of TiCl3 are offset by a larger reduction in hydrogen capacity of the mixtures.

  13. Cholinesterase inhibitors and memory.

    Science.gov (United States)

    Pepeu, Giancarlo; Giovannini, Maria Grazia

    2010-09-06

    A consensus exists that cholinesterase inhibitors (ChEIs) are efficacious for mild to moderate Alzheimer's Disease (AD). Unfortunately, the number of non-responders is large and the therapeutic effect is usually short-lasting. In experimental animals, ChEIs exert three main actions: inhibit cholinesterase (ChE), increase extracellular levels of brain acetylcholine (ACh), improve cognitive processes, particularly when disrupted in models of AD. In this overview we shall deal with the cognitive processes that are improved by ChEI treatment because they depend on the integrity of brain cholinergic pathways and their activation. The role of cholinergic system in cognition can be investigated using different approaches. Microdialysis experiments demonstrate the involvement of the cholinergic system in attention, working, spatial and explicit memory, information encoding, sensory-motor gating, skill learning. No involvement in long-term memory has yet been demonstrated. Conversely, memory consolidation is facilitated by low cholinergic activity. Experiments on healthy human subjects, notwithstanding caveats concerning age, dose, and different memory tests, confirm the findings of animal experiments and demonstrate that stimulation of the cholinergic system facilitates attention, stimulus detection, perceptual processing and information encoding. It is not clear whether information retrieval may be improved but memory consolidation is reduced by cholinergic activation. ChEI effects in AD patients have been extensively investigated using rating scales that assess cognitive and behavioural responses. Few attempts have been made to identify which scale items respond better to ChEIs and therefore, presumably, depend on the activity of the cholinergic system. Improvement in attention and executive functions, communication, expressive language and mood stability have been reported. Memory consolidation and retrieval may be impaired by high ACh levels. Therefore, considering

  14. Characterization of inhibitor(s) of β-glucuronidase enzyme activity in GUS-transgenic wheat

    KAUST Repository

    Ramadan, Ahmed M Ali

    2011-06-26

    The uidA gene, encoding for β-glucuronidase (GUS), is the most frequently used reporter gene in plants. As a reporter enzyme, GUS can be assayed both qualitatively and quantitatively. In wheat, there are numerous reports of failure in detecting GUS enzyme activity in tissues of transgenic plants, while other reports have suggested presence of β-glucuronidase inhibitor(s) in wheat tissues. In the present study, we show that the β-glucuronidase enzyme activity is not only tissue-specific but also genotype-dependent. Our data demonstrate that the glucuronic acid could be the candidate inhibitor for β-glucuronidase enzyme activity in wheat leaves and roots. It should be noted that the assays to detect β-glucuronidase enzyme activity in wheat should be interpreted carefully. Based on the data of our present study, we recommend studying the chemical pathways, the unintended effects and the possible loss-of-function of any candidate transgene prior to transformation experiments. © 2011 Springer Science+Business Media B.V.

  15. [ACE inhibitors and the kidney].

    Science.gov (United States)

    Hörl, W H

    1996-01-01

    Treatment with ACE inhibitors results in kidney protection due to reduction of systemic blood pressure, intraglomerular pressure, an antiproliferative effect, reduction of proteinuria and a lipid-lowering effect in proteinuric patients (secondary due to reduction of protein excretion). Elderly patients with diabetes melitus, coronary heart disease or peripheral vascular occlusion are at risk for deterioration of kidney function due to a high frequency of renal artery stenosis in these patients. In patients with renal insufficiency dose reduction of ACE inhibitors is necessary (exception: fosinopril) but more important is the risk for development of hyperkalemia. Patients at risk for renal artery stenosis and patients pretreated with diuretics should receive a low ACE inhibitor dosage initially ("start low - go slow"). For compliance reasons once daily ACE inhibitor dosage is recommended.

  16. Application of Molecular Modeling to Urokinase Inhibitors Development

    Directory of Open Access Journals (Sweden)

    V. B. Sulimov

    2014-01-01

    Full Text Available Urokinase-type plasminogen activator (uPA plays an important role in the regulation of diverse physiologic and pathologic processes. Experimental research has shown that elevated uPA expression is associated with cancer progression, metastasis, and shortened survival in patients, whereas suppression of proteolytic activity of uPA leads to evident decrease of metastasis. Therefore, uPA has been considered as a promising molecular target for development of anticancer drugs. The present study sets out to develop the new selective uPA inhibitors using computer-aided structural based drug design methods. Investigation involves the following stages: computer modeling of the protein active site, development and validation of computer molecular modeling methods: docking (SOL program, postprocessing (DISCORE program, direct generalized docking (FLM program, and the application of the quantum chemical calculations (MOPAC package, search of uPA inhibitors among molecules from databases of ready-made compounds to find new uPA inhibitors, and design of new chemical structures and their optimization and experimental examination. On the basis of known uPA inhibitors and modeling results, 18 new compounds have been designed, calculated using programs mentioned above, synthesized, and tested in vitro. Eight of them display inhibitory activity and two of them display activity about 10 μM.

  17. Studies on terrein as a new class of proteasome inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Demasi, M.; Felicio, A.L.; Lima, C. [Instituto Butantan, Sao Paulo, SP (Brazil); Pacheco, A.O.; Leite, H.G.; Andrade, L.H. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica], e-mail: marimasi@butantan.gov.br

    2010-07-01

    The proteasome is an intracellular multicatalytic protease involved in the cell cycle regulation, signaling response, antigen presentation and apoptosis. Since proteasome inhibitors promote cell death by apoptosis, they have been proposed as new anti-tumoral drugs. Terrein, a secondary metabolite secreted by the fungus Aspergillus terreus, was firstly described in 1935. In the present work we report that terrein isolated through the screening for inhibitors of the 20S proteasome showed inhibitory effect upon both chymotrypsin- and trypsin-like activities of the multicatalytic core particle, the 20S proteasome. Despite of the high inhibitory concentration determined in vitro, that verified by incubating cells (fibroblasts and a pulmonary tumor cell line) in the presence of terrein was 4-fold lower indicating the proteasome as a selective intracellular target. Moreover, terrein promoted apoptotic cell death on both fibroblasts and pulmonary tumor cell line tested. Although terrein concentrations (mM range) necessary to elicit apoptosis in the cellular models herein tried were high when compared to those (muM and nM range) of other inhibitors recently described, its chemical structure is not correlated to any other inhibitor reported thus far. Therefore, the present results point out for the possibility of exploring terrein as a new molecular fragment for the development of synthetic proteasome inhibitors. (author)

  18. a -Glucosidase Inhibitors from Dendrobium tortile

    Directory of Open Access Journals (Sweden)

    Rachawadee Limpanit

    2016-03-01

    Full Text Available From the whole plant of Dendrobium tortile, a new compound, namely 4-(2-hydroxypropyl-2(5H-furanone, was isolated, together with six known compounds, which included trans-tetracosylferulate (2, cis-docosylferulate (3, p-hydroxybenzaldehyde (4, 3,4-dihydroxy-3,4 ¢ -dimethoxybibenzyl (5, (2S-eriodictyol (6 and dendrofalconerol A (7. The structures of these compounds were determined through analysis of 1-D and 2-D NMR and HR-ESI-MS data. All of the isolates were evaluated for their a -glucosidase inhibitory activity. Compound 7 showed strong a -glucosidase inhibitory activity when compared with the positive control acarbose, whereas compounds 5 and 6 exhibited appreciable effects. An enzyme kinetic study revealed that compound 7 is a non-competitive inhibitor of a -glucosidase. This is the first report of the chemical constituents with biological activity from D. tortile.

  19. Mechanistic insights into chemical and photochemical transformations of bismuth vanadate photoanodes

    Science.gov (United States)

    Toma, Francesca M.; Cooper, Jason K.; Kunzelmann, Viktoria; McDowell, Matthew T.; Yu, Jie; Larson, David M.; Borys, Nicholas J.; Abelyan, Christine; Beeman, Jeffrey W.; Yu, Kin Man; Yang, Jinhui; Chen, Le; Shaner, Matthew R.; Spurgeon, Joshua; Houle, Frances A.; Persson, Kristin A.; Sharp, Ian D.

    2016-07-01

    Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and composition under solar water splitting conditions reveals chemical instabilities that are not predicted from thermodynamic considerations of stable solid oxide phases, as represented by the Pourbaix diagram for the system. Computational modelling indicates that photoexcited charge carriers accumulated at the surface destabilize the lattice, and that self-passivation by formation of a chemically stable surface phase is kinetically hindered. Although chemical stability of metal oxides cannot be assumed, insight into corrosion mechanisms aids development of protection strategies and discovery of semiconductors with improved stability.

  20. Force-induced chemical reactions on the metal centre in a single metalloprotein molecule

    Science.gov (United States)

    Zheng, Peng; Arantes, Guilherme M.; Field, Martin J.; Li, Hongbin

    2015-06-01

    Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions.

  1. Force-induced chemical reactions on the metal centre in a single metalloprotein molecule.

    Science.gov (United States)

    Zheng, Peng; Arantes, Guilherme M; Field, Martin J; Li, Hongbin

    2015-06-25

    Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions.

  2. Chelation: A Fundamental Mechanism of Action of AGE Inhibitors, AGE Breakers, and Other Inhibitors of Diabetes Complications

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Rhoji; Murray, David B.; Metz, Thomas O.; Baynes, John

    2012-03-01

    Advanced glycation or glycoxidation end-products (AGE) increase in tissue proteins with age, and their rate of accumulation is increased in diabetes, nephropathy and inflammatory diseases. AGE inhibitors include a range of compounds that are proposed to act by trapping carbonyl and dicarbonyl intermediates in AGE formation. However, some among the newer generation of AGE inhibitors lack reactive functional groups that would trap reaction intermediates, indicating an alternative mechanism of action. We propose that AGE inhibitors function primarily as chelators, inhibiting metal-catalyzed oxidation reactions. The AGE-inhibitory activity of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers is also consistent with their chelating activity. Finally, compounds described as AGE breakers, or their hydrolysis products, also have strong chelating activity, suggesting that these compounds also act through their chelating activity. We conclude that chelation is the common, and perhaps the primary, mechanism of action of AGE inhibitors and breakers, and that chronic, mild chelation therapy should prove useful in treatment of diabetes and age-related diseases characterized by oxidative stress, inflammation and increased chemical modification of tissue proteins by advanced glycoxidation and lipoxidation end-products.

  3. Modelisation of the regulation of protein synthesis following fertilization in sea urchin shows requirement of two processes: a destabilization of eIF4E:4E-BP complex and a great stimulation of the 4E-BP-degradation mechanism, both rapamycin-sensitive.

    Directory of Open Access Journals (Sweden)

    Sébastien eLaurent

    2014-05-01

    Full Text Available Fertilization of sea urchin eggs involves an increase in protein synthesis associated with a decrease in the amount of the translation initiation inhibitor 4E-BP. A highly simple reaction model for the regulation of protein synthesis was built and was used to simulate the physiological changes in the total 4E-BP amount observed during time after fertilization. Our study evidenced that two changes occurring at fertilization are necessary to fit with experimental data. The first change was an 8 fold increase in the dissociation parameter (koff1 of the eIF4E:4E-BP complex. The second was an important 32.5 fold activation of the degradation mechanism of the protein 4E-BP. Additionally, the changes in both processes should occur in five minutes time interval post fertilization. To validate the model, we checked that the kinetic of the predicted 4.2 fold increase of eIF4E:eIF4G complex concentration at fertilization matched the increase of protein synthesis experimentally observed after fertilization (6.6 fold, SD=2.3, n=8. The minimal model was also used to simulate changes observed after fertilization in the presence of rapamycin, a FRAP/mTOR inhibitor. The model showed that the eIF4E:4E-BP complex destabilization was impacted and, surprisingly, that the mechanism of 4E-BP degradation was also strongly affected, therefore suggesting that both processes are controlled by the protein kinase FRAP/mTOR.

  4. Discovery of a Potent Class I Protein Arginine Methyltransferase Fragment Inhibitor.

    Science.gov (United States)

    Ferreira de Freitas, Renato; Eram, Mohammad S; Szewczyk, Magdalena M; Steuber, Holger; Smil, David; Wu, Hong; Li, Fengling; Senisterra, Guillermo; Dong, Aiping; Brown, Peter J; Hitchcock, Marion; Moosmayer, Dieter; Stegmann, Christian M; Egner, Ursula; Arrowsmith, Cheryl; Barsyte-Lovejoy, Dalia; Vedadi, Masoud; Schapira, Matthieu

    2016-02-11

    Protein methyltransferases (PMTs) are a promising target class in oncology and other disease areas. They are composed of SET domain methyltransferases and structurally unrelated Rossman-fold enzymes that include protein arginine methyltransferases (PRMTs). In the absence of a well-defined medicinal chemistry tool-kit focused on PMTs, most current inhibitors were identified by screening large and diverse libraries of leadlike molecules. So far, no successful fragment-based approach was reported against this target class. Here, by deconstructing potent PRMT inhibitors, we find that chemical moieties occupying the substrate arginine-binding site can act as efficient fragment inhibitors. Screening a fragment library against PRMT6 produced numerous hits, including a 300 nM inhibitor (ligand efficiency of 0.56) that decreased global histone 3 arginine 2 methylation in cells, and can serve as a warhead for the development of PRMT chemical probes.

  5. Planarization properties of an alkaline slurry without an inhibitor on copper patterned wafer CMP

    Institute of Scientific and Technical Information of China (English)

    Wang Chenwei; Liu Yuling; Tian Jianying; Niu Xinhuan; Zheng Weiyan; Yue Hongwei

    2012-01-01

    The chemical mechanical polishing/planarization (CMP) performance of an inhibitor-free alkaline copper slurry is investigated.The results of the Cu dissolution rate (DR) and the polish rate (PR) show that the alkaline slurry without inhibitors has a relatively high copper removal rate and considerable dissolution rate.Although the slurry with inhibitors has a somewhat low DR,the copper removal rate was significantly reduced due to the addition of inhibitors (Benzotriazole,BTA).The results obtained from pattern wafers show that the alkaline slurry withoutinhibitors has a better planarization efficacy; it can planarize the uneven patterned surface during the excess copper removal.These results indicate that the proposed inhibitor-free copper slurry has a considerable planarization capability for CMP of Cu pattern wafers,it can be applied in the first step ofCu CMP for copper bulk removal.

  6. Virtual Screening for Transition State Analogue Inhibitors of IRAP Based on Quantum Mechanically Derived Reaction Coordinates.

    Science.gov (United States)

    Svensson, Fredrik; Engen, Karin; Lundbäck, Thomas; Larhed, Mats; Sköld, Christian

    2015-09-28

    Transition state and high energy intermediate mimetics have the potential to be very potent enzyme inhibitors. In this study, a model of peptide hydrolysis in the active site of insulin-regulated aminopeptidase (IRAP) was developed using density functional theory calculations and the cluster approach. The 3D structure models of the reaction coordinates were used for virtual screening to obtain new chemical starting points for IRAP inhibitors. This mechanism-based virtual screening process managed to identify several known peptidase inhibitors from a library of over 5 million compounds, and biological testing identified one compound not previously reported as an IRAP inhibitor. This novel methodology for virtual screening is a promising approach to identify new inhibitors mimicking key transition states or intermediates of an enzymatic reaction.

  7. Identification of thioredoxin glutathione reductase inhibitors that kill cestode and trematode parasites.

    Science.gov (United States)

    Ross, Fabiana; Hernández, Paola; Porcal, Williams; López, Gloria V; Cerecetto, Hugo; González, Mercedes; Basika, Tatiana; Carmona, Carlos; Fló, Martín; Maggioli, Gabriela; Bonilla, Mariana; Gladyshev, Vadim N; Boiani, Mariana; Salinas, Gustavo

    2012-01-01

    Parasitic flatworms are responsible for serious infectious diseases that affect humans as well as livestock animals in vast regions of the world. Yet, the drug armamentarium available for treatment of these infections is limited: praziquantel is the single drug currently available for 200 million people infected with Schistosoma spp. and there is justified concern about emergence of drug resistance. Thioredoxin glutathione reductase (TGR) is an essential core enzyme for redox homeostasis in flatworm parasites. In this work, we searched for flatworm TGR inhibitors testing compounds belonging to various families known to inhibit thioredoxin reductase or TGR and also additional electrophilic compounds. Several furoxans and one thiadiazole potently inhibited TGRs from both classes of parasitic flatworms: cestoda (tapeworms) and trematoda (flukes), while several benzofuroxans and a quinoxaline moderately inhibited TGRs. Remarkably, five active compounds from diverse families possessed a phenylsulfonyl group, strongly suggesting that this moiety is a new pharmacophore. The most active inhibitors were further characterized and displayed slow and nearly irreversible binding to TGR. These compounds efficiently killed Echinococcus granulosus larval worms and Fasciola hepatica newly excysted juveniles in vitro at a 20 µM concentration. Our results support the concept that the redox metabolism of flatworm parasites is precarious and particularly susceptible to destabilization, show that furoxans can be used to target both flukes and tapeworms, and identified phenylsulfonyl as a new drug-hit moiety for both classes of flatworm parasites.

  8. Identification of thioredoxin glutathione reductase inhibitors that kill cestode and trematode parasites.

    Directory of Open Access Journals (Sweden)

    Fabiana Ross

    Full Text Available Parasitic flatworms are responsible for serious infectious diseases that affect humans as well as livestock animals in vast regions of the world. Yet, the drug armamentarium available for treatment of these infections is limited: praziquantel is the single drug currently available for 200 million people infected with Schistosoma spp. and there is justified concern about emergence of drug resistance. Thioredoxin glutathione reductase (TGR is an essential core enzyme for redox homeostasis in flatworm parasites. In this work, we searched for flatworm TGR inhibitors testing compounds belonging to various families known to inhibit thioredoxin reductase or TGR and also additional electrophilic compounds. Several furoxans and one thiadiazole potently inhibited TGRs from both classes of parasitic flatworms: cestoda (tapeworms and trematoda (flukes, while several benzofuroxans and a quinoxaline moderately inhibited TGRs. Remarkably, five active compounds from diverse families possessed a phenylsulfonyl group, strongly suggesting that this moiety is a new pharmacophore. The most active inhibitors were further characterized and displayed slow and nearly irreversible binding to TGR. These compounds efficiently killed Echinococcus granulosus larval worms and Fasciola hepatica newly excysted juveniles in vitro at a 20 µM concentration. Our results support the concept that the redox metabolism of flatworm parasites is precarious and particularly susceptible to destabilization, show that furoxans can be used to target both flukes and tapeworms, and identified phenylsulfonyl as a new drug-hit moiety for both classes of flatworm parasites.

  9. Phenotypic screening approaches to develop Aurora kinase inhibitors: Drug Discovery perspectives

    Directory of Open Access Journals (Sweden)

    Carlos eMarugán

    2016-01-01

    Full Text Available Targeting mitotic regulators as a strategy to fight cancer implies the development of drugs against key proteins such as Aurora A and B. Current drugs which target mitosis through a general mechanism of action (stabilization/destabilization of microtubules, have several side effects (neutropenia, alopecia, emesis. Pharmaceutical companies aim at avoiding these unwanted effects by generating improved and selective drugs that increase the quality of life of the patients. However, the development of these drugs is an ambitious task that involves testing thousands of compounds through biochemical and cell-based assays. In addition, molecules usually target complex biological processes, involving several proteins and different molecular pathways, further emphasizing the need for high-throughput screening techniques and multiplexing technologies in order to identify drugs with the desired phenotype.We will briefly describe two multiplexing technologies (high-content imaging, microarrays and flow cytometry and two key processes for drug discovery research (assay development and validation following our own published industry quality standards. We will further focus on high-content imaging as a useful tool for phenotypic screening and will provide a concrete example of high-content imaging assay to detect Aurora A or B selective inhibitors discriminating the off-target effects related to inhibition of other cell cycle or non-cell cycle key regulators. Finally, we will describe other assays that can help to characterize the in vitro pharmacology of the inhibitors.

  10. Nitric oxide synthase inhibitors containing the carboxamidine group or its isosteres

    Energy Technology Data Exchange (ETDEWEB)

    Proskuryakov, Sergei Ya; Konoplyannikov, Anatoly G; Skvortzov, Valery G [Medical Radiological Research Centre, Russian Academy of Medical Sciences (Russian Federation); Mandrugin, Andrey A; Fedoseev, Vladimir M [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2005-09-30

    The review summarises structures, activities and selectivity of NO-synthase (NOS) inhibitors belonging to various classes of chemical compounds. Linear, cyclic and heterocyclic structures containing guanidine, amidine and/or isothiourea fragments are considered. The structure-activity relationships for these inhibitors were analysed in relation to their action on the inducible NOS isoform. This analysis can provide the basis for the synthesis of new more efficient compounds.

  11. [Study on derivatives of 5-amino-4-acylamino-1H-pyrazole as inhibitors of furin].

    Science.gov (United States)

    Kibirev, V K; Osadchuk, T V; Vadziuk, O B; Shablykin, O V; Kozachenko, A P; Chumachenko, S A; Popil'nichenko, S V; Brovarets, V S

    2011-01-01

    A series of 5-amino-1H-pyrazoles was synthesized and studied as inhibitors of furin. The most potent compound, 5-amino-4-acetylamino-3-(4-methylphenylamino)1H-pyrazole, was found to retard the activity of furin by mixed-type inhibition with K = 288 microM. These findings permit to plan new ways for chemical modifications of the 5-amino-1H-pyrazole structure and design more potent furin inhibitors of non-peptide nature.

  12. Chemical Mahjong

    Science.gov (United States)

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

  13. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil biodeg

  14. Pharmacophore modeling for protein tyrosine phosphatase 1B inhibitors.

    Science.gov (United States)

    Bharatham, Kavitha; Bharatham, Nagakumar; Lee, Keun Woo

    2007-05-01

    A three dimensional chemical feature based pharmacophore model was developed for the inhibitors of protein tyrosine phosphatase 1B (PTP1B) using the CATALYST software, which would provide useful knowledge for performing virtual screening to identify new inhibitors targeted toward type II diabetes and obesity. A dataset of 27 inhibitors, with diverse structural properties, and activities ranging from 0.026 to 600 microM, was selected as a training set. Hypol, the most reliable quantitative four featured pharmacophore hypothesis, was generated from a training set composed of compounds with two H-bond acceptors, one hydrophobic aromatic and one ring aromatic features. It has a correlation coefficient, RMSD and cost difference (null cost-total cost) of 0.946, 0.840 and 65.731, respectively. The best hypothesis (Hypol) was validated using four different methods. Firstly, a cross validation was performed by randomizing the data using the Cat-Scramble technique. The results confirmed that the pharmacophore models generated from the training set were valid. Secondly, a test set of 281 molecules was scored, with a correlation of 0.882 obtained between the experimental and predicted activities. Hypol performed well in correctly discriminating the active and inactive molecules. Thirdly, the model was investigated by mapping on two PTP1B inhibitors identified by different pharmaceutical companies. The Hypol model correctly predicted these compounds as being highly active. Finally, docking simulations were performed on few compounds to substantiate the role of the pharmacophore features at the binding site of the protein by analyzing their binding conformations. These multiple validation approaches provided confidence in the utility of this pharmacophore model as a 3D query for virtual screening to retrieve new chemical entities showing potential as potent PTP1B inhibitors.

  15. Copper(II) ions increase plasminogen activator inhibitor type 1 dynamics in key structural regions that govern stability

    DEFF Research Database (Denmark)

    Bucci, Joel C; Trelle, Morten Beck; McClintock, Carlee S;

    2016-01-01

    demonstrated that Cu(II) and other transition metals modulate the stability of PAI-1, exhibiting effects that are dependent on the presence or absence of the somatomedin B (SMB) domain of VN. The study presented here dissects the changes in molecular dynamics underlying the destabilizing effects of Cu...... effects are not a result of coordination of Cu(II) to these histidine residues. Finally, addition of Cu(II) results in an acceleration of the local unfolding kinetics of PAI-1 presumed to be on pathway to the latency conversion. The effect of ligands on the dynamics of PAI-1 adds another intriguing......Plasminogen activator inhibitor type 1 (PAI-1) regulates the fibrinolysis pathway by inhibiting the protease activity of plasminogen activators. PAI-1 works in concert with vitronectin (VN), an extracellular protein that aids in localization of active PAI-1 to tissues. The Peterson laboratory...

  16. Diverse inhibitors of aflatoxin biosynthesis.

    Science.gov (United States)

    Holmes, Robert A; Boston, Rebecca S; Payne, Gary A

    2008-03-01

    Pre-harvest and post-harvest contamination of maize, peanuts, cotton, and tree nuts by members of the genus Aspergillus and subsequent contamination with the mycotoxin aflatoxin pose a widespread food safety problem for which effective and inexpensive control strategies are lacking. Since the discovery of aflatoxin as a potently carcinogenic food contaminant, extensive research has been focused on identifying compounds that inhibit its biosynthesis. Numerous diverse compounds and extracts containing activity inhibitory to aflatoxin biosynthesis have been reported. Only recently, however, have tools been available to investigate the molecular mechanisms by which these inhibitors affect aflatoxin biosynthesis. Many inhibitors are plant-derived and a few may be amenable to pathway engineering for tissue-specific expression in susceptible host plants as a defense against aflatoxin contamination. Other compounds show promise as protectants during crop storage. Finally, inhibitors with different modes of action could be used in comparative transcriptional and metabolomic profiling experiments to identify regulatory networks controlling aflatoxin biosynthesis.

  17. Corrosion inhibitors from expired drugs.

    Science.gov (United States)

    Vaszilcsin, Nicolae; Ordodi, Valentin; Borza, Alexandra

    2012-07-15

    This paper presents a method of expired or unused drugs valorization as corrosion inhibitors for metals in various media. Cyclic voltammograms were drawn on platinum in order to assess the stability of pharmaceutically active substances from drugs at the metal-corrosive environment interface. Tafel slope method was used to determine corrosion rates of steel in the absence and presence of inhibitors. Expired Carbamazepine and Paracetamol tablets were used to obtain corrosion inhibitors. For the former, the corrosion inhibition of carbon steel in 0.1 mol L(-1) sulfuric acid solution was about 90%, whereas for the latter, the corrosion inhibition efficiency of the same material in the 0.25 mol L(-1) acetic acid-0.25 mol L(-1) sodium acetate buffer solution was about 85%.

  18. Synthesis of New Indole Derivatives Structurally Related to Donepezil and Their Biological Evaluation as Acetylcholinesterase Inhibitors

    Directory of Open Access Journals (Sweden)

    Samar I. Faggal

    2012-04-01

    Full Text Available New series of indole derivatives analogous to donepezil, a well known anti-Alzheimer and acetylcholinesterase inhibitor drug, was synthesized. A full chemical characterization of the new compounds is provided. Biological evaluation of the new compounds as acetylcholinesterase inhibitors was performed. Most of the compounds were found to have potent acetylcholinesterase inhibitor activity compared to donepezil as standard. The compound 1-(2-(4-(2-fluorobenzyl piperazin-1-ylacetylindoline-2,3-dione (IIId was found to be the most potent.

  19. Uncovering Molecular Bases Underlying Bone Morphogenetic Protein Receptor Inhibitor Selectivity.

    Directory of Open Access Journals (Sweden)

    Abdelaziz Alsamarah

    Full Text Available Abnormal alteration of bone morphogenetic protein (BMP signaling is implicated in many types of diseases including cancer and heterotopic ossifications. Hence, small molecules targeting BMP type I receptors (BMPRI to interrupt BMP signaling are believed to be an effective approach to treat these diseases. However, lack of understanding of the molecular determinants responsible for the binding selectivity of current BMP inhibitors has been a big hindrance to the development of BMP inhibitors for clinical use. To address this issue, we carried out in silico experiments to test whether computational methods can reproduce and explain the high selectivity of a small molecule BMP inhibitor DMH1 on BMPRI kinase ALK2 vs. the closely related TGF-β type I receptor kinase ALK5 and vascular endothelial growth factor receptor type 2 (VEGFR2 tyrosine kinase. We found that, while the rigid docking method used here gave nearly identical binding affinity scores among the three kinases; free energy perturbation coupled with Hamiltonian replica-exchange molecular dynamics (FEP/H-REMD simulations reproduced the absolute binding free energies in excellent agreement with experimental data. Furthermore, the binding poses identified by FEP/H-REMD led to a quantitative analysis of physical/chemical determinants governing DMH1 selectivity. The current work illustrates that small changes in the binding site residue type (e.g. pre-hinge region in ALK2 vs. ALK5 or side chain orientation (e.g. Tyr219 in caALK2 vs. wtALK2, as well as a subtle structural modification on the ligand (e.g. DMH1 vs. LDN193189 will cause distinct binding profiles and selectivity among BMP inhibitors. Therefore, the current computational approach represents a new way of investigating BMP inhibitors. Our results provide critical information for designing exclusively selective BMP inhibitors for the development of effective pharmacotherapy for diseases caused by aberrant BMP signaling.

  20. Progesterone receptor chaperone complex-based highthroughput screening assay: identification of capsaicin as inhibitor of Hsp90 machine

    Science.gov (United States)

    Patwardhan, Chaitanya A.; Alfa, Eyad; Lu, Su; Chadli, Ahmed

    2016-01-01

    Hsp90 and its co-chaperones are known to be important for cancer cell survival. The N-terminal inhibitors of Hsp90 that are in ongoing clinical trials as anti-tumor agents have unfortunately shown disappointing efficacies in the clinic. Thus, novel inhibitors of the Hsp90 machine with different mechanism of action are urgently needed. We report here the development of a novel high-throughput drug-screening (HTS) assay platform to identify small molecule inhibitors of Hsp90 and its co-chaperones. This assay quantitatively measures the ability of Hsp90 and its co-chaperones to refold/protect the progesterone receptor (PR), a physiological client of Hsp90, in 96-well plate format. We screened the NIH clinical collection drug library and identified capsaicin as a hit molecule. Capsaicin is an FDA-approved drug for topical use in pain management. Cell survival assays showed that capsaicin selectively kills cancer cells and destabilizes several Hsp90 client proteins. Thus, our data may explain the seemingly pleotropic effect of capsaicin. PMID:25184514

  1. Chemical morphogenesis: turing patterns in an experimental chemical system.

    Science.gov (United States)

    Dulos, E; Boissonade, J; Perraud, J J; Rudovics, B; De Kepper, P

    1996-11-01

    Patterns resulting from the sole interplay between reaction and diffusion are probably involved in certain stages of morphogenesis in biological systems, as initially proposed by Alan Turing. Self-organization phenomena of this type can only develop in nonlinear systems (i.e. involving positive and negative feedback loops) maintained far from equilibrium. We present Turing patterns experimentally observed in a chemical system. An oscillating chemical reaction, the CIMA reaction, is operated in an open spatial reactor designed in order to obtain a pure reaction-diffusion system. The two types of Turing patterns observed, hexagonal arrays of spots and parallel stripes, are characterized by an intrinsic wavelength. We identify the origin of the necessary diffusivity between activator and inhibitor. We also describe a pattern growth mechanism by spot splitting that recalls cell division.

  2. Mescaline-induced changes of brain-cortex ribosomes. Role of sperimidine in counteracting the destabilizing effect of mescaline of brain-cortex ribosomes.

    Science.gov (United States)

    Datta, R K; Antopol, W; Ghosh, J J

    1971-11-01

    1. The effect of spermidine on the mescaline-induced changes of brain-cortex ribosomes was studied by adding spermidine during the treatment of goat brain-cortex slices with mescaline. 2. Mescaline treatment of brain-cortex slices removed a portion of the endogenous spermidine from ribosomes and this removal was significantly prevented when spermidine was present during mescaline treatment. 3. Spermidine present during mescaline treatment of brain-cortex slices counteracted, to some extent, the destabilizing effect of mescaline on ribosomes with respect to heat denaturation. 4. Mescaline treatment of brain-cortex slices made ribosomes more susceptible to breakdown, releasing protein and RNA, and resulting in loss of ribosomal enzymic activities. However, spermidine present during mescaline treatment counteracted moderately the mescaline-induced ribosomal susceptibility to breakdown and ribosomal loss of enzymic activities. 5. Ribosomes of mescaline-treated cortex slices were rapidly degraded by ribonuclease and trypsin. However, if spermidine was present during mescaline treatment of brain-cortex slices the rates of degradation diminished.

  3. Mutation of histidine residues in CP47 leads to destabilization of the photosystem II complex and to impairment of light energy transfer.

    Science.gov (United States)

    Shen, G; Eaton-Rye, J J; Vermaas, W F

    1993-05-18

    Site-directed mutagenesis has been used to change conserved histidine residues in hydrophobic regions of the photosystem II chlorophyll-binding protein CP47 in the cyanobacterium Synechocystis sp. PCC 6803. Nine mutants with one, four mutants with two, and four mutants with three His mutations in CP47 have been generated and characterized. Mutation of any one of seven different His residues to Tyr leads to slower photoautotrophic growth and apparent destabilization of the PS II complex. Mutations introduced into multiple His residues in one mutant exhibited a cumulative effect. Replacing His by Asn leads to a much smaller effect than observed upon mutation to Tyr. This is consistent with the hypothesis that the mutated His residues are chlorophyll ligands: Asn can substitute as chlorophyll ligand, whereas Tyr cannot. Further evidence supporting a role of the mutated His residues in chlorophyll binding comes from measurements of the light intensity needed to half-saturate oxygen evolution. All His mutants with impaired PS II function needed higher light intensities for half-saturation than wild type. A possible explanation for this decrease in antenna efficiency in the mutants is a loss of the Mg in the chlorophyll due to a loss of the fifth ligand, and thus the formation of a pheophytin molecule in the antenna. We conclude that conserved His residues in hydrophobic regions of CP47 indeed are chlorophyll ligands and that these ligands are important for PS II stability as well as efficient antenna function.

  4. Soil Organic C and N Destabilization and Decline Following a Decade of Free-air CO2 Enrichment (FACE) in an Aridland Ecosystem

    Science.gov (United States)

    Strahm, B. D.; Sparks, J. P.

    2009-12-01

    Arid and semiarid environments constitute ~40% of the earth’s land surface and are expected to be particularly susceptible to global change factors. As a result, there may be dramatic shifts in the biogeochemistry of soil C and N in these systems that will have implications on productivity and long-term C sink/source dynamics. We have observed a 14-32% decrease in soil organic C and N concentrations in response to a decade of free-air CO2 enrichment (FACE) in the Mojave Desert at the Nevada Desert FACE Facility. The variability in the magnitude of change is largely driven by cover type. Soils under the dominant forms of vegetative cover, Larrea tridentata and Lycium sp. contained up to an order of magnitude more organic C and N than adjacent areas of bare ground, often colonized by biological soil crusts, and exhibited much larger shifts in the bioavailability of these pools in response to future atmospheric CO2 concentrations. Although elevated CO2 resulted in a nearly universal decrease in active cycling organic C and N (40-88%) across all cover types, a decrease of up to 28% was observed in the resistant, or slowly cycling, organic C and N pools under the dominant vegetation. Such changes suggest that predicted future atmospheric CO2 concentrations may contribute to the significant destabilization of soil organic C and N stocks in arid ecosystems, resulting in declines in productivity and negative feedbacks to rising atmospheric C concentrations.

  5. Proton pump inhibitors and gastroenteritis

    NARCIS (Netherlands)

    R.J. Hassing (Robert); A. Verbon (Annelies); H. de Visser (Herman); A. Hofman (Albert); B.H.Ch. Stricker (Bruno)

    2016-01-01

    textabstractAn association between proton pump inhibitor (PPI) therapy and bacterial gastroenteritis has been suggested as well as contradicted. The aim of this study was to examine the association between the use of PPIs and occurrence of bacterial gastroenteritis in the prospective Rotterdam Study

  6. Corrosion Inhibitors for Reinforced Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  7. Renal targeting of kinase inhibitors

    NARCIS (Netherlands)

    Dolman, M. E. M.; Fretz, M. M.; Segers, Gj. W.; Lacombe, M.; Prakash, J.; Storm, G.; Hennink, W. E.; Kok, R. J.

    2008-01-01

    Activation of proximal tubular cells by fibrotic and inflammatory mediators is an important hallmark of chronic kidney disease. We have developed a novel strategy to intervene in renal fibrosis, by means of locally delivered kinase inhibitors. Such compounds will display enhanced activity within tub

  8. Anti-Angiogenic Therapy: Strategies to Develop Potent VEGFR-2 Tyrosine Kinase Inhibitors and Future Prospect.

    Science.gov (United States)

    Shi, Leilei; Zhou, Jianfeng; Wu, Jifeng; Shen, Yuemao; Li, Xun

    2016-01-01

    Tumor angiogenesis has always been a major gap for effective cancer therapy. Interruption of aberrant angiogenesis by specific inhibitors targeting receptor tyrosine kinases (RTKs) has been of great interests to medicinal chemists. Among the factors that are involved in tumor angiogenesis, vascular endothelial growth factor receptor-2 (VEGFR-2) is validated as the most closely related factor which can drive angiogenesis through binding with its natural ligand VEGF. The well-validated VEGF-driven VEGFR-2 signaling pathway can stimulate many endothelial responses, including increasing vessel permeability and enhancing endothelial cell proliferation, migration and differentiation. Consequently, circumventing angiogenesis by VEGFR-2 inhibitors represents a promising strategy for counteracting various VEGFR-2-mediated disorders as well as drug resistance. Over the past decades, a considerable number of novel small molecular VEGFR-2 inhibitors have been exploited with diverse chemical scaffolds. Especially, recent frequently launched inhibitors have declared their research values and therapeutic potentials in oncology. Still, the antiangiogenesis based treatment remains an ongoing challenge. In this review, a comprehensive retrospective of newly emerged VEGFR-2 inhibitors have been summarized, with the emphasis on the structure-activity relationship (SAR) investigation, and also binding patterns of representative inhibitors with biotargets. On the basis of all of this information, varied strategies for developing potent VEGFR-2 inhibitors and the future prospect of the clinical application of antiangiogenic inhibitors are discussed hereby.

  9. Calcium pentosan polysulfate is a multifaceted exosite inhibitor of aggrecanases.

    Science.gov (United States)

    Troeberg, Linda; Fushimi, Kazunari; Khokha, Rama; Emonard, Hervé; Ghosh, Peter; Nagase, Hideaki

    2008-10-01

    Degradation of the cartilage proteoglycan aggrecan is a key early event in the development of osteoarthritis. Adamalysin with thrombospondin motifs (ADAMTS) -4 and ADAMTS-5 are considered to be the main enzymes responsible for aggrecan breakdown, making them attractive drugs targets. Here we show that calcium pentosan polysulfate (CaPPS), a chemically sulfated xylanopyranose from beechwood, is a multifaceted exosite inhibitor of the aggrecanases and protects cartilage against aggrecan degradation. CaPPS interacts with the noncatalytic spacer domain of ADAMTS-4 and the cysteine-rich domain of ADAMTS-5, blocking activity against their natural substrate aggrecan with inhibitory concentration 50 values of 10-40 nM but only weakly inhibiting hydrolysis of a nonglycosylated recombinant protein substrate. In addition, CaPPS increased cartilage levels of tissue inhibitor of metalloproteinases-3 (TIMP-3), an endogenous inhibitor of ADAMTS-4 and -5. This was due to the ability of CaPPS to block endocytosis of TIMP-3 mediated by low-density lipoprotein receptor-related protein. CaPPS also increased the affinity of TIMP-3 for ADAMTS-4 and -5 by more than 100-fold, improving the efficacy of TIMP-3 as an aggrecanase inhibitor. Studies with TIMP-3-null mouse cartilage indicated that CaPPS inhibition of aggrecan degradation is TIMP-3 dependent. These unique properties make CaPPS a prototypic disease-modifying agent for osteoarthritis.

  10. From polypharmacology to target specificity: the case of PARP inhibitors.

    Science.gov (United States)

    Liscio, Paride; Camaioni, Emidio; Carotti, Andrea; Pellicciari, Roberto; Macchiarulo, Antonio

    2013-01-01

    Poly(ADP-ribose)polymerases (PARPs) catalyze a post-transcriptional modification of proteins, consisting in the attachment of mono, oligo or poly ADP-ribose units from NAD+ to specific polar residues of target proteins. The scientific interest in members of this superfamily of enzymes is continuously growing since they have been implicated in a range of diseases including stroke, cardiac ischemia, cancer, inflammation and diabetes. Despite some inhibitors of PARP-1, the founder member of the superfamily, have advanced in clinical trials for cancer therapy, and other members of PARPs have recently been proposed as interesting drug targets, challenges exist in understanding the polypharmacology of current PARP inhibitors as well as developing highly selective chemical tools to unravel specific functions of each member of the superfamily. Beginning with an overview on the molecular aspects that affect polypharmacology, in this article we discuss how these may have an impact on PARP research and drug discovery. Then, we review the most selective PARP inhibitors hitherto reported in literature, giving an update on the molecular aspects at the basis of selective PARP inhibitor design. Finally, some outlooks on current issues and future directions in this field of research are also provided.

  11. Analysis of Different Inhibitors for Magnesium Investment Casting

    Science.gov (United States)

    Herrero-Dorca, N.; Sarriegi Etxeberria, H.; Hurtado, I.; Andres, U.; Rodriguez, P.; Arruebarrena, G.

    2012-01-01

    Investment casting of magnesium is a well suited process for the production of aeronautic and automotive components. But still, this process has not been properly developed. One reason for that are the reactions between the Mg melt and the ceramics of the mould that produce a non-desired oxide layer on the part surface. These reactions can be inhibited by the use of silica-free slurries with a higher stability than conventional ones. Another way is using inhibitors, chemical compounds based in fluorides that react with the melt, creating a protective surface layer in the casting. With the aim of developing a reaction-free process, alumina moulds with a stepped geometry have been constructed. These provide different interface conditions. Conventional SF6, non-conventional KBF4 and NaBF4 and environmentally friendly FK inhibitors have been tested on. As a result, KBF4 has been identified as the most suitable inhibitor for magnesium investment casting. Furthermore, the analysis of the cooling curve of different interfaces has provided essential information about the reaction mechanism of the inhibitors.

  12. Isolation and partial identification of eight endogenous G1 inhibitors of JB-1 ascites tumor cell proliferation.

    Science.gov (United States)

    Barfod, N M

    1982-06-01

    Eight endogenous G1 inhibitors of the proliferation of JB-1 ascites tumor cells have been isolated and characterized. The activity of the inhibitors has been analyzed on synchronized JB-1 (murine plasmacytoma) and L1A2 (murine sarcoma) cells in vitro using flow cytometry. The purified inhibitors have been tested for in vivo activity on partially synchronized JB-1 and L1A2 ascites tumors in situ. Four of the inhibitors exhibited a high degree of cell specificity (chalone-like inhibitors) and were chemically related, whereas the other four showed no cell specificity. In most extractions, the amount of cell-specific activity is more than 50% of the total G1-inhibitory activity. Most of the inhibitors are low-molecular-weight peptides and glycopeptides.

  13. Structural and regulatory elements of HCV NS5B polymerase--β-loop and C-terminal tail--are required for activity of allosteric thumb site II inhibitors.

    Directory of Open Access Journals (Sweden)

    Sarah E Boyce

    Full Text Available Elucidation of the mechanism of action of the HCV NS5B polymerase thumb site II inhibitors has presented a challenge. Current opinion holds that these allosteric inhibitors stabilize the closed, inactive enzyme conformation, but how this inhibition is accomplished mechanistically is not well understood. Here, using a panel of NS5B proteins with mutations in key regulatory motifs of NS5B--the C-terminal tail and β-loop--in conjunction with a diverse set of NS5B allosteric inhibitors, we show that thumb site II inhibitors possess a distinct mechanism of action. A combination of enzyme activity studies and direct binding assays reveals that these inhibitors require both regulatory elements to maintain the polymerase inhibitory activity. Removal of either element has little impact on the binding affinity of thumb site II inhibitors, but significantly reduces their potency. NS5B in complex with a thumb site II inhibitor displays a characteristic melting profile that suggests stabilization not only of the thumb domain but also the whole polymerase. Successive truncations of the C-terminal tail and/or removal of the β-loop lead to progressive destabilization of the protein. Furthermore, the thermal unfolding transitions characteristic for thumb site II inhibitor-NS5B complex are absent in the inhibitor-bound constructs in which interactions between C-terminal tail and β-loop are abolished, pointing to the pivotal role of both regulatory elements in communication between domains. Taken together, a comprehensive picture of inhibition by compounds binding to thumb site II emerges: inhibitor binding provides stabilization of the entire polymerase in an inactive, closed conformation, propagated via coupled interactions between the C-terminal tail and β-loop.

  14. Chemical carcinogenesis

    Directory of Open Access Journals (Sweden)

    Paula A. Oliveira

    2007-12-01

    Full Text Available The use of chemical compounds benefits society in a number of ways. Pesticides, for instance, enable foodstuffs to be produced in sufficient quantities to satisfy the needs of millions of people, a condition that has led to an increase in levels of life expectancy. Yet, at times, these benefits are offset by certain disadvantages, notably the toxic side effects of the chemical compounds used. Exposure to these compounds can have varying effects, ranging from instant death to a gradual process of chemical carcinogenesis. There are three stages involved in chemical carcinogenesis. These are defined as initiation, promotion and progression. Each of these stages is characterised by morphological and biochemical modifications and result from genetic and/or epigenetic alterations. These genetic modifications include: mutations in genes that control cell proliferation, cell death and DNA repair - i.e. mutations in proto-oncogenes and tumour suppressing genes. The epigenetic factors, also considered as being non-genetic in character, can also contribute to carcinogenesis via epigenetic mechanisms which silence gene expression. The control of responses to carcinogenesis through the application of several chemical, biochemical and biological techniques facilitates the identification of those basic mechanisms involved in neoplasic development. Experimental assays with laboratory animals, epidemiological studies and quick tests enable the identification of carcinogenic compounds, the dissection of many aspects of carcinogenesis, and the establishment of effective strategies to prevent the cancer which results from exposure to chemicals.A sociedade obtém numerosos benefícios da utilização de compostos químicos. A aplicação dos pesticidas, por exemplo, permitiu obter alimento em quantidade suficiente para satisfazer as necessidades alimentares de milhões de pessoas, condição relacionada com o aumento da esperança de vida. Os benefícios estão, por

  15. Quantum Chemical Study on the Corrosion Inhibition of Some Oxadiazoles

    Directory of Open Access Journals (Sweden)

    Hong Ju

    2015-01-01

    Full Text Available Quantum chemical calculations based on DFT method were performed on three nitrogen-bearing heterocyclic compounds used as corrosion inhibitors for the mild steel in acid media to determine the relationship between the molecular structure of inhibitors and inhibition efficiency. The structural parameters, such as energy and distribution of highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO, the charge distribution of the studied inhibitors, the absolute electronegativity (χ values, and the fraction of electrons (ΔN transfer from inhibitors to mild steel were also calculated and correlated with inhibition efficiencies. The results showed that the inhibition efficiency of inhibitors increased with the increase in energy of HOMO and decrease in energy gap of frontier molecular orbital, and the areas containing N and O atoms are most possible sites for bonding the steel surface by donating electrons to the mild steel.

  16. Chemical ligation methods for the tagging of DNA-encoded chemical libraries.

    Science.gov (United States)

    Keefe, Anthony D; Clark, Matthew A; Hupp, Christopher D; Litovchick, Alexander; Zhang, Ying

    2015-06-01

    The generation of DNA-encoded chemical libraries requires the unimolecular association of multiple encoding oligonucleotides with encoded chemical entities during combinatorial synthesis processes. This has traditionally been achieved using enzymatic ligation. We discuss a range of chemical ligation methods that provide alternatives to enzymatic ligation. These chemical ligation methods include the generation of modified internucleotide linkages that support polymerase translocation and other modified linkages that while not supporting the translocation of polymerases can also be used to generate individual cDNA molecules containing encoded chemical information specifying individual library members. We also describe which of these approaches have been successfully utilized for the preparation of DNA-encoded chemical libraries and those that were subsequently used for the discovery of inhibitors.

  17. Chemical cosmology

    CERN Document Server

    Boeyens, Jan CA

    2010-01-01

    The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp

  18. Destabilizing Bodies, Destabilizing Disciplines: Practicing Liminality in Music Therapy

    Directory of Open Access Journals (Sweden)

    Cindy LaCom

    2014-11-01

    Full Text Available Our project began with a consideration of how disability studies might enrich the practice of music therapy. Originally, we were interested in how a greater awareness of disability issues might help music therapists, especially because of the often medicalized (and arguably pathologized implications of the terms (“health” and “help” which define their field and which frame the therapist/client relationship. On these grounds, we argued that greater awareness of the cultural context for such implications might aid the therapist. At the outset, it seemed straightforward enough. But our own unstable embodiments kept disrupting our conversations. The corporeal intransigencies of our bodies as we dealt with the symptoms of Crohn’s disease, autism and multiple sclerosis moved us beyond a critique of disciplinary purity which constructs each field as distinct to an analysis of privilege, power and passing that extends to multiple disciplines and pedagogical practices. In our paper, we raise questions about how the illusion of (stable bodies can reinforce hierarchies (between therapist/client, teacher/student, helper/helped, ablebodied/disabled, especially when the person “in charge” does not have to disclose or discuss the instability of her own body. Upon that privilege rests an array of power dynamics, and we believe that a purposeful contemplation of our own embodiment has to be more central to praxis, whether as therapists, scholars, teachers or professionals. To do this, we must be aware not only of others’ but also of our own relationship to disability -- socially, culturally, and as a marker of identity and potential (inaccess to power.

  19. Nicotinamide phosphoribosyltransferase inhibitors, design, preparation and SAR

    DEFF Research Database (Denmark)

    Christensen, Mette Knak; Erichsen, Kamille Dumong; Olesen, Uffe Hogh;

    2013-01-01

    Existing pharmacological inhibitors for nicotinamide phosphoribosyltransferase (NAMPT) are promising therapeutics for treating cancer. Using medicinal and computational chemistry methods, the structure-activity relationship for novel classes of NAMPT inhibitors is described and compounds optimized....... Compounds are designed inspired by the NAMPT inhibitor APO866 and cyanoguanidine inhibitor scaffolds. In comparison with recently published derivatives the new analogues exhibit an equally potent anti-proliferative activity in vitro and comparable activity in vivo. The best performing compounds from...

  20. Allosteric small-molecule kinase inhibitors

    DEFF Research Database (Denmark)

    Wu, Peng; Clausen, Mads Hartvig; Nielsen, Thomas E.

    2015-01-01

    current barriers of kinase inhibitors, including poor selectivity and emergence of drug resistance. In spite of the small number of identified allosteric inhibitors in comparison with that of inhibitors targeting the ATP pocket, encouraging results, such as the FDA-approval of the first small...

  1. Chromenopyridin derivatives as environmentally benign corrosion inhibitors for N80

    Directory of Open Access Journals (Sweden)

    K.R. Ansari

    2017-02-01

    Full Text Available This research work was to investigate the corrosion inhibition performance of two newly synthesized chromenopyridine derivatives namely 2,4-diamino-5-(phenylthio-5H-chromeno[2,3-b]pyridine-3-carbonitrile (PPC-1 and 2,4-diamino-5-phenoxy-5H-chromeno[2,3-b]pyridine-3-carbonitrile (PPC-2 as potential environmentally friendly corrosion inhibitors for N80 steel in 15% hydrochloric acid (HCl. Various techniques like gravimetric, electrochemical impedance spectroscopy (EIS, Tafel polarizations, scanning electron microscope (SEM and atomic force microscopy (AFM have been used. The inhibition efficiencies given by PPC-1 and PPC-2 at 200 mg L−1 are 92.4% and 82.1% respectively. Tafel polarization revealed that both inhibitors are cathodic in nature. Langmuir adsorption isotherm was found to be the best fit. The experimental result was further supported by quantum chemical study.

  2. Cyclin Dependent Kinase 9 Inhibitors for Cancer Therapy.

    Science.gov (United States)

    Sonawane, Yogesh A; Taylor, Margaret A; Napoleon, John Victor; Rana, Sandeep; Contreras, Jacob I; Natarajan, Amarnath

    2016-10-13

    Cyclin dependent kinase (CDK) inhibitors have been the topic of intense research for nearly 2 decades due to their widely varied and critical functions within the cell. Recently CDK9 has emerged as a druggable target for the development of cancer therapeutics. CDK9 plays a crucial role in transcription regulation; specifically, CDK9 mediated transcriptional regulation of short-lived antiapoptotic proteins is critical for the survival of transformed cells. Focused chemical libraries based on a plethora of scaffolds have resulted in mixed success with regard to the development of selective CDK9 inhibitors. Here we review the regulation of CDK9, its cellular functions, and common core structures used to target CDK9, along with their selectivity profile and efficacy in vitro and in vivo.

  3. Identification of novel inhibitors of dietary lipid absorption using zebrafish.

    Directory of Open Access Journals (Sweden)

    Justin D Clifton

    Full Text Available Pharmacological inhibition of dietary lipid absorption induces favorable changes in serum lipoprotein levels in patients that are at risk for cardiovascular disease and is considered an adjuvant or alternative treatment with HMG-CoA reductase inhibitors (statins. Here we demonstrate the feasibility of identifying novel inhibitors of intestinal lipid absorption using the zebrafish system. A pilot screen of an unbiased chemical library identified novel compounds that inhibited processing of fluorescent lipid analogues in live zebrafish larvae. Secondary assays identified those compounds suitable for testing in mammals and provided insight into mechanism of action, which for several compounds could be distinguished from ezetimibe, a drug used to inhibit cholesterol absorption in humans that broadly inhibited lipid absorption in zebrafish larvae. These findings support the utility of zebrafish screening assays to identify novel compounds that target complex physiological processes.

  4. Decomposition of energetic chemicals contaminated with iron or stainless steel.

    Science.gov (United States)

    Chervin, Sima; Bodman, Glenn T; Barnhart, Richard W

    2006-03-17

    Contamination of chemicals or reaction mixtures with iron or stainless steel is likely to take place during chemical processing. If energetic and thermally unstable chemicals are involved in a manufacturing process, contamination with iron or stainless steel can impact the decomposition characteristics of these chemicals and, subsequently, the safety of the processes, and should be investigated. The goal of this project was to undertake a systematic approach to study the impact of iron or stainless steel contamination on the decomposition characteristics of different chemical classes. Differential scanning calorimetry (DSC) was used to study the decomposition reaction by testing each chemical pure, and in mixtures with iron and stainless steel. The following classes of energetic chemicals were investigated: nitrobenzenes, tetrazoles, hydrazines, hydroxylamines and oximes, sulfonic acid derivatives and monomers. The following non-energetic groups were investigated for contributing effects: halogens, hydroxyls, amines, amides, nitriles, sulfonic acid esters, carbonyl halides and salts of hydrochloric acid. Based on the results obtained, conclusions were drawn regarding the sensitivity of the decomposition reaction to contamination with iron and stainless steel for the chemical classes listed above. It was demonstrated that the most sensitive classes are hydrazines and hydroxylamines/oximes. Contamination of these chemicals with iron or stainless steel not only destabilizes them, leading to decomposition at significantly lower temperatures, but also sometimes causes increased severity of the decomposition. The sensitivity of nitrobenzenes to contamination with iron or stainless steel depended upon the presence of other contributing groups: the presence of such groups as acid chlorides or chlorine/fluorine significantly increased the effect of contamination on decomposition characteristics of nitrobenzenes. The decomposition of sulfonic acid derivatives and tetrazoles

  5. Conversion of calcineurin inhibitors with mammalian target of rapamycin inhibitors after kidney transplant.

    Science.gov (United States)

    Nikoueinejad, Hassan; Soleimani, Alireza; Mirshafiey, Abbas; Amirzargar, Aliakbar; Sarrafnejad, Abdolfattah; Kamkar, Ideh; Einollahi, Behzad

    2013-02-01

    One way to overcome chronic allograft nephropathy induced by calcineurin inhibitors in immunosuppression protocols for organ transplants is to replace such inhibitors with mammalian target of rapamycin inhibitors, which are not clinically nephrotoxic because they have better renal function. If patients tolerate replacement, there could be a clear preference for mammalian target of rapamycin inhibitors as a maintenance immunosuppressant after renal transplant. This replacement could be sufficient if it were used for a certain time after calcineurin inhibitors. This review considers the conversion effects of calcineurin inhibitors with mammalian target of rapamycin inhibitors from the view point of kidney function during different periods after a kidney transplant.

  6. Multiphysics modelling, quantum chemistry and risk analysis for corrosion inhibitor design and lifetime prediction.

    Science.gov (United States)

    Taylor, C D; Chandra, A; Vera, J; Sridhar, N

    2015-01-01

    Organic corrosion inhibitors can provide an effective means to extend the life of equipment in aggressive environments, decrease the environmental, economic, health and safety risks associated with corrosion failures and enable the use of low cost steels in place of corrosion resistant alloys. To guide the construction of advanced models for the design and optimization of the chemical composition of organic inhibitors, and to develop predictive tools for inhibitor performance as a function of alloy and environment, a multiphysics model has been constructed following Staehle's principles of "domains and microprocesses". The multiphysics framework provides a way for science-based modelling of the various phenomena that impact inhibitor efficiency, including chemical thermodynamics and speciation, oil/water partitioning, effect of the inhibitor on multiphase flow, surface adsorption and self-assembled monolayer formation, and the effect of the inhibitor on cathodic and anodic reaction pathways. The fundamental tools required to solve the resulting modelling from a first-principles perspective are also described. Quantification of uncertainty is significant to the development of lifetime prediction models, due to their application for risk management. We therefore also discuss how uncertainty analysis can be coupled with the first-principles approach laid out in this paper.

  7. Structure and mechanism of action of the hydroxy aryl aldehyde class of IRE1 endoribonuclease inhibitors

    Science.gov (United States)

    Sanches, Mario; Duffy, Nicole M.; Talukdar, Manisha; Thevakumaran, Nero; Chiovitti, David; Canny, Marella D.; Lee, Kenneth; Kurinov, Igor; Uehling, David; Al-awar, Rima; Poda, Gennadiy; Prakesch, Michael; Wilson, Brian; Tam, Victor; Schweitzer, Colleen; Toro, Andras; Lucas, Julie L.; Vuga, Danka; Lehmann, Lynn; Durocher, Daniel; Zeng, Qingping; Patterson, John B.; Sicheri, Frank

    2014-01-01

    Endoplasmic reticulum (ER) stress activates the unfolded protein response and its dysfunction is linked to multiple diseases. The stress transducer IRE1α is a transmembrane kinase endoribonuclease (RNase) that cleaves mRNA substrates to re-establish ER homeostasis. Aromatic ring systems containing hydroxy-aldehyde moieties, termed hydroxy aryl aldehydes (HAA), selectively inhibit IRE1α RNase and thus represent a novel chemical series for therapeutic development. We solved crystal structures of murine IRE1α in complex with three HAA inhibitors. HAA inhibitors engage a shallow pocket at the RNase active site through pi-stacking interactions with His910 and Phe889, an essential Schiff base with Lys907 and a H-bond with Tyr892. Structure activity studies and mutational analysis of contact residues define the optimal chemical space of inhibitors and validate the inhibitor binding site. These studies lay the foundation for understanding both the biochemical and cellular functions of IRE1α using small molecule inhibitors and suggest new avenues for inhibitor design. PMID:25164867

  8. Notch Inhibitors for Cancer Treatment

    OpenAIRE

    Espinoza, Ingrid; Miele, Lucio

    2013-01-01

    Notch signaling is an evolutionarily conserved cell signaling pathway involved in cell fate during development, stem cell renewal and differentiation in postnatal tissues. Roles for Notch in carcinogenesis, in the biology of cancer stem cells and tumor angiogenesis have been reported. These features identify Notch as a potential therapeutic target in oncology. Based on the molecular structure of Notch receptor, Notch ligands and Notch activators, a set of Notch pathway inhibitors have been de...

  9. Nelfinavir: fourth protease inhibitor approved.

    Science.gov (United States)

    1997-01-01

    The Food and Drug Administration (FDA) has granted accelerated approval to nelfinavir in both adult and pediatric formulations. Agouron, the manufacturer, used innovative computerized drug design techniques to discover, design, and refine the nelfinavir molecule. Nelfinavir is marketed under the trade name Viracept, and costs $5,000 per year. Early clinical trials find it to be as powerful as the other protease inhibitors, but with a different resistance profile. The drug has relatively few drug indications; however, several compounds have been contraindicated.

  10. The stress-related, rhizobial small RNA RcsR1 destabilizes the autoinducer synthase encoding mRNA sinI in Sinorhizobium meliloti.

    Science.gov (United States)

    Baumgardt, Kathrin; Šmídová, Klára; Rahn, Helen; Lochnit, Günter; Robledo, Marta; Evguenieva-Hackenberg, Elena

    2016-05-03

    Quorum sensing is a cell density-dependent communication system of bacteria relying on autoinducer molecules. During the analysis of the post-transcriptional regulation of quorum sensing in the nitrogen fixing plant symbiont Sinorhizobium meliloti, we predicted and verified a direct interaction between the 5'-UTR of sinI mRNA encoding the autoinducer synthase and a small RNA (sRNA), which we named RcsR1. In vitro, RcsR1 prevented cleavage in the 5'-UTR of sinI by RNase E and impaired sinI translation. In line with low ribosomal occupancy and transcript destabilization upon binding of RcsR1 to sinI, overproduction of RcsR1 in S. meliloti resulted in lower level and shorter half-life of sinI mRNA, and in decreased autoinducer amount. Although RcsR1 can influence quorum sensing via sinI, its level did not vary at different cell densities, but decreased under salt stress and increased at low temperature. We found that RcsR1 and its stress-related expression pattern, but not the interaction with sinI homologs, are conserved in Sinorhizobium, Rhizobium and Agrobacterium. Consistently, overproduction of RcsR1 in S. meliloti and Agrobacterium tumefaciens inhibited growth at high salinity. We identified conserved targets of RcsR1 and showed that most conserved interactions and the effect on growth under salt stress are mediated by the first stem-loop of RcsR1, while its central part is responsible for the species-specific interaction with sinI. We conclude that RcsR1 is an ancient, stress-related riboregulator in rhizobia and propose that it links stress responses to quorum sensing in S. meliloti.

  11. The biofilm matrix destabilizers, EDTA and DNaseI, enhance the susceptibility of nontypeable Hemophilus influenzae biofilms to treatment with ampicillin and ciprofloxacin.

    Science.gov (United States)

    Cavaliere, Rosalia; Ball, Jessica L; Turnbull, Lynne; Whitchurch, Cynthia B

    2014-08-01

    Nontypeable Hemophilus influenzae (NTHi) is a Gram-negative bacterial pathogen that causes chronic biofilm infections of the ears and airways. The biofilm matrix provides structural integrity to the biofilm and protects biofilm cells from antibiotic exposure by reducing penetration of antimicrobial compounds into the biofilm. Extracellular DNA (eDNA) has been found to be a major matrix component of biofilms formed by many species of Gram-positive and Gram-negative bacteria, including NTHi. Interestingly, the cation chelator ethylenediaminetetra-acetic acid (EDTA) has been shown to reduce the matrix strength of biofilms of several bacterial species as well as to have bactericidal activity against various pathogens. EDTA exerts its antimicrobial activity by chelating divalent cations necessary for growth and membrane stability and by destabilizing the matrix thus enhancing the detachment of bacterial cells from the biofilm. In this study, we have explored the role of divalent cations in NTHi biofilm development and stability. We have utilized in vitro static and continuous flow models of biofilm development by NTHi to demonstrate that magnesium cations enhance biofilm formation by NTHi. We found that the divalent cation chelator EDTA is effective at both preventing NTHi biofilm formation and at treating established NTHi biofilms. Furthermore, we found that the matrix destablilizers EDTA and DNaseI increase the susceptibility of NTHi biofilms to ampicillin and ciprofloxacin. Our observations indicate that DNaseI and EDTA enhance the efficacy of antibiotic treatment of NTHi biofilms. These observations may lead to new strategies that will improve the treatment options available to patients with chronic NTHi infections.

  12. Auto-ubiquitination-induced degradation of MALT1-API2 prevents BCL10 destabilization in t(11;18(q21;q21-positive MALT lymphoma.

    Directory of Open Access Journals (Sweden)

    Heidi Noels

    Full Text Available BACKGROUND: The translocation t(11;18(q21;q21 is the most frequent chromosomal aberration associated with MALT lymphoma and results in constitutive NF-kappaB activity via the expression of an API2-MALT1 fusion protein. The properties of the reciprocal MALT1-API2 were never investigated as it was reported to be rarely transcribed. PRINCIPAL FINDINGS: Our data indicate the presence of MALT1-API2 transcripts in the majority of t(11;18(q21;q21-positive MALT lymphomas. Based on the breakpoints in the MALT1 and API2 gene, the MALT1-API2 protein contains the death domain and one or both immunoglobulin-like domains of MALT1 (approximately 90% of cases--mediating the possible interaction with BCL10--fused to the RING domain of API2. Here we show that this RING domain enables MALT1-API2 to function as an E3 ubiquitin ligase for BCL10, inducing its ubiquitination and proteasomal degradation in vitro. Expression of MALT1-API2 transcripts in t(11;18(q21;q21-positive MALT lymphomas was however not associated with a reduction of BCL10 protein levels. CONCLUSION: As we observed MALT1-API2 to be an efficient target of its own E3 ubiquitin ligase activity, our data suggest that this inherent instability of MALT1-API2 prevents its accumulation and renders a potential effect on MALT lymphoma development via destabilization of BCL10 unlikely.

  13. A Chimeric Cetuximab-Functionalized Corona as a Potent Delivery System for Microtubule-Destabilizing Nanocomplexes to Hepatocellular Carcinoma Cells: A Focus on EGFR and Tubulin Intracellular Dynamics.

    Science.gov (United States)

    Poojari, Radhika; Kini, Sudarshan; Srivastava, Rohit; Panda, Dulal

    2015-11-01

    In this study, we have developed microtubule destabilizing agents combretastatin A4 (CA4) or 2-methoxyestradiol (2ME) encapsulated poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol) (PLGA-b-PEG) nanocomplexes for targeted delivery to human hepatocellular carcinoma (HCC) cells. An epidermal growth factor receptor (EGFR) is known to be overexpressed in HCC cells. Therefore, the targeting moiety cetuximab (Cet), an anti-EGFR chimeric monoclonal antibody, is functionalized on the surface of these diblock copolymeric coronas. Cetuximab is associated with the extracellular domain of the EGFR; therefore, the uptake of the cetuximab conjugated nanocomplexes occurred efficiently in EGFR overexpressing HCC cells indicating potent internalization of the complex. The cetuximab targeted-PLGA-b-PEG nanocomplexes encapsulating CA4 or 2ME strongly inhibited phospho-EGFR expression, depolymerized microtubules, produced spindle abnormalities, stalled mitosis, and induced apoptosis in Huh7 cells compared to the free drugs, CA4 or 2ME. Further, the combinatorial strategy of targeted nanocomplexes, Cet-PLGA-b-PEG-CA4 NP and Cet-PLGA-b-PEG-2ME NP, significantly reduced the migration of Huh7 cells, and markedly enhanced the anticancer effects of the microtubule-targeted drugs in Huh7 cells compared to the free drugs, CA4 or 2ME. The results indicated that EGFR receptor-mediated internalization via cetuximab facilitated enhanced uptake of the nanocomplexes leading to potent anticancer efficacy in Huh7 cells. Cetuximab-functionalized PLGA-b-PEG nanocomplexes possess a strong potential for the targeted delivery of CA4 or 2ME in EGFR overexpressed HCC cells, and the strategy may be useful for selectively targeting microtubules in these cells.

  14. Study of Morphological Changes in MgH2 Destabilized LiBH4 Systems Using Computed X-ray Microtomography

    Directory of Open Access Journals (Sweden)

    Leslie G. Butler

    2012-09-01

    Full Text Available The objective of this study was to apply three-dimensional x-ray microtomographic imaging to understanding morphologies in the diphasic destabilized hydride system: MgH2 and LiBH4. Each of the single phase hydrides as well as two-phase mixtures at LiBH4:MgH2 ratios of 1:3, 1:1, and 2:1 were prepared by high energy ball milling for 5 minutes (with and without 4 mol % TiCl3 catalyst additions. Samples were imaged using computed microtomography in order to (i establish measurement conditions leading to maximum absorption contrast between the two phases and (ii determine interfacial volume. The optimal energy for measurement was determined to be 15 keV (having 18% transmission for the MgH2 phase and above 90% transmission for the LiBH4 phase. This work also focused on the determination of interfacial volume. Results showed that interfacial volume for each of the single phase systems, LiBH4 and MgH2, did not change much with catalysis using 4 mol % TiCl3. However, for the mixed composite system, interphase boundary volume was always higher in the catalyzed system; increasing from 15% to 33% in the 1:3 system, from 11% to 20% in the 1:1 system, and 2% to 14% in the 2:1 system. The parameters studied are expected to govern mass transport (i.e., diffusion and ultimately lead to microstructure-based improvements on H2 desorption and uptake rates.

  15. Inhibitors of protein kinase C

    Institute of Scientific and Technical Information of China (English)

    LIU Shiying; JIANG Yuyang; CAO Jian; LIU Feng; MA Li; ZHAO Yufen

    2005-01-01

    Protein kinase catalyzes the transfer of the γ-phosphoryl group from ATP to the hydroxyl groups of protein side chains, which plays critical roles in signal transduction pathways by transmitting extracellular signals across the plasma membrane and nuclear membrane to the destination sites in the cytoplasm and the nucleus. Protein kinase C (PKC) is a superfamily of phospholipid-dependent Ser/Thr kinase. There are at least 12 isozymes in PKC family. They are distributed in different tissues and play different roles in physiological processes. On account of their concern with a variety of pathophysiologic states, such as cancer, inflammatory conditions, autoimmune disorder, and cardiac diseases, the inhibitors, which can inhibit the activity of PKC and the interaction of cytokine with receptor, and interfere signal transduction pathway, may be candidates of therapeutic drugs. Therefore, intense efforts have been made to develop specific protein kinase inhibitors as biological tools and therapeutic agents. This article reviews the recent development of some of PKC inhibitors based on their interaction with different conserved domains and different inhibition mechanisms.

  16. Carbonic anhydrase inhibitors drug design.

    Science.gov (United States)

    McKenna, Robert; Supuran, Claudiu T

    2014-01-01

    Inhibition of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) has pharmacologic applications in the field of antiglaucoma, anticonvulsant, antiobesity, and anticancer agents but is also emerging for designing anti-infectives (antifungal and antibacterial agents) with a novel mechanism of action. As a consequence, the drug design of CA inhibitors (CAIs) is a very dynamic field. Sulfonamides and their isosteres (sulfamates/sulfamides) constitute the main class of CAIs which bind to the metal ion in the enzyme active site. Recently the dithiocarbamates, possessing a similar mechanism of action, were reported as a new class of inhibitors. Other families of CAIs possess a distinct mechanism of action: phenols, polyamines, some carboxylates, and sulfocoumarins anchor to the zinc-coordinated water molecule. Coumarins and five/six-membered lactones are prodrug inhibitors, binding in hydrolyzed form at the entrance of the active site cavity. Novel drug design strategies have been reported principally based on the tail approach for obtaining all these types of CAIs, which exploit more external binding regions within the enzyme active site (in addition to coordination to the metal ion), leading thus to isoform-selective compounds. Sugar-based tails as well as click chemistry were the most fruitful developments of the tail approach. Promising compounds that inhibit CAs from bacterial and fungal pathogens, of the dithiocarbamate, phenol and carboxylate types have also been reported.

  17. Tubulin acetylation promoting potency and absorption efficacy of deacetylase inhibitors

    Science.gov (United States)

    Mangas-Sanjuan, V; Oláh, J; Gonzalez-Alvarez, I; Lehotzky, A; Tőkési, N; Bermejo, M; Ovádi, J

    2015-01-01

    Background and Purpose Histone deacetylase 6 (HDAC6) and silent information regulator 2 (SIRT2) control the dynamics of the microtubule network via their deacetylase activities. Tubulin polymerization promoting protein (TPPP/p25) enhances microtubule acetylation by its direct binding to HDAC6. Our objective was to characterize the multiple interactions of the deacetylases and to establish the inhibitory potency and the pharmacokinetic features of the deacetylase inhibitors, trichostatin A (TSA) and AGK2. Experimental Approach The interactions of deacetylases with tubulin and TPPP/p25 were quantified by elisa using human recombinant proteins. The effect of inhibitors on the tubulin acetylation was established in HeLa cells transfected with pTPPP and CG-4 cells expressing TPPP/p25 endogenously by celisa (elisa on cells), Western blot and immunofluorescence microscopy. The pharmacokinetic features of the inhibitors were evaluated by in situ kinetic modelling of their intestinal transport in rats. Key Results Deacetylases interact with both tubulin and TPPP/p25, notwithstanding piggy-back binding of HDAC6 or SIRT2 to the TPPP/p25-associated tubulin was established. Much higher inhibitory potency for TSA than for AGK2 was detected in both HeLa and CG-4 cells. Pioneer pharmacokinetic studies revealed passive diffusion and diffusion coupled with secretion for TSA and AGK2 respectively. Both inhibitors exhibited greater permeability than some other well-established drugs. Conclusions and Implications TPPP/p25-directed deacetylase inhibition provides mechanisms for the fine control of the dynamics and stability of the microtubule network. Deacetylase inhibitors with chemical structures similar to TSA and AGK2 appear to be excellent candidates for oral drug absorption. PMID:25257800

  18. The development and performance testing of a biodegradable scale inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Julie; Fidoe, Steve; Jones, Chris

    2006-03-15

    The oil industry is currently facing severe restrictions concerning the discharge of oil field chemicals into the environment. Many commonly used materials in both topside and downhole applications are phased for substitution for use in the North Sea, and more will be identified. The development of biodegradable and low toxicity chemicals, which afford equal or improved efficacy, compared to conventional technology, available at a competitive price, is a current industry challenge. A range of biodegradable materials are increasingly available, however their limited performance can result in a restricted range of applications. This paper discusses the development and commercialization of a readily biodegradable scale inhibitor, ideal for use in topside applications. This material offers a broad spectrum of activity, notably efficiency against barium sulphate, calcium sulphate and calcium carbonate scales, in a range of water chemistries. A range of performance testing, compatibility, stability and OCNS dataset will be presented. Comparisons with commonly used chemicals have been made to identify the superior performance of this phosphate ester. This paper will discuss a scale inhibitor suitable for use in a variety of conditions which offers enhanced performance combined with a favourable biodegradation profile. This material is of great benefit to the industry, particularly in North Sea applications. (author) (tk)

  19. Chemical Analyses

    Science.gov (United States)

    Bulluck, J. W.; Rushing, R. A.

    1994-01-01

    As a preliminary study on the effects of chemical aging of polymer materials MERL and TRI have examined two polymeric materials that are typically used for offshore umbilical applications. These two materials were Tefzel, a copolymer of ethylene and tetrafluoroethylene, and Coflon, polyvinylidene fluoride. The Coflon specimens were cut from pipe sections and exposed to H2S at various temperatures and pressures. One of these specimens was tested for methane permeation, and another for H2S permeation. The Tefzel specimens were cut from .05 mm sheet stock material and were exposed to methanol at elevated temperature and pressure. One of these specimens was exposed to methanol permeation for 2 days at 100 C and 2500 psi. An additional specimen was exposed to liquid methanol for 3 days at 150 C and 15 Bar. Virgin specimens of each material were similarly prepared and tested.

  20. A cyclic peptidic serine protease inhibitor

    DEFF Research Database (Denmark)

    Zhao, Baoyu; Xu, Peng; Jiang, Longguang;

    2014-01-01

    Peptides are attracting increasing interest as protease inhibitors. Here, we demonstrate a new inhibitory mechanism and a new type of exosite interactions for a phage-displayed peptide library-derived competitive inhibitor, mupain-1 (CPAYSRYLDC), of the serine protease murine urokinase...... pocket, its carbonyl group aligning improperly relative to Ser195 and the oxyanion hole, explaining why the peptide is an inhibitor rather than a substrate. Substitution of the P1 Arg with novel unnatural Arg analogues with aliphatic or aromatic ring structures led to an increased affinity, depending...... of this peptidic inhibitor, a concept different from conventional attempts at improving inhibitor affinity by reducing the entropic burden....

  1. Conformation-specific inhibitors of Raf kinases.

    Science.gov (United States)

    Wang, Xiaolun; Schleicher, Kristin

    2013-01-01

    Since the discovery linking B-Raf mutations to human tumors in 2002, significant advances in the development of Raf inhibitors have been made, leading to the recent approval of two Raf inhibitor drugs. This chapter includes a brief introduction to B-Raf as a validated target and focuses on the three different binding modes observed with Raf small-molecule inhibitors. These various binding modes lock the Raf kinase in different conformations that impact the toxicity profiles of the inhibitors. Possible solutions to mitigate the side effects caused by inhibitor-induced dimerization are also discussed.

  2. Collision between chemically-driven self-propelled drops

    CERN Document Server

    Yabunaka, Shunsuke

    2016-01-01

    We consider analytically and numerically head-on collision between two self-propelled drops. Each drop is driven by chemical reactions that produce or consume the concentration isotropically. The isotropic distribution of the concentration field is destabilized by motion of the drop which is itself made by Marangoni flow from concentration-dependent surface tension. This symmetry-breaking self-propulsion is distinct from other self-propulsion mechanisms due to the intrinsic polarity such as squirmers and self-phoretic motion; there is a bifurcation point below which the drop is stationary and above which it moves spontaneously. When two drops moving along the same axis with opposite direction, the interactions arise both from hydrodynamics and concentration overlap. We found that two drops exhibit either elastic collision or fusion depending on the distance from the bifurcation point controlled, for instance, by viscosity. The elastic collision results from the balance between dissipation and energy injection...

  3. De novo design of caseinolytic protein proteases inhibitors based on pharmacophore and 2D molecular fingerprints.

    Science.gov (United States)

    Wu, Guanzhong; Zhang, Zhen; Chen, Hong; Lin, Kejiang

    2015-06-01

    Caseinolytic protein proteases (ClpP) are large oligomeric protein complexes that contribute to cell homeostasis as well as virulence regulation in bacteria. Inhibitors of ClpP can significantly attenuate the capability to produce virulence factors of the bacteria. In this work, we developed a workflow to expand the chemical space of potential ClpP inhibitors based on a set of β-lactones. In our workflow, an artificial pharmacophore model was generated based on HipHop and HYPOGEN method. A de novo compound library based on molecular fingerprints was constructed and virtually screened by the pharmacophore model. The results were further investigated by molecular docking study. The workflow successfully achieved potential ClpP inhibitors. It could be applied to design more novel potential ClpP inhibitors and provide theoretical basis for the further optimization of the hit compounds.

  4. Selective Inhibitors of Cyclin G Associated Kinase (GAK) as Anti-Hepatitis C Agents.

    Science.gov (United States)

    Kovackova, Sona; Chang, Lei; Bekerman, Elena; Neveu, Gregory; Barouch-Bentov, Rina; Chaikuad, Apirat; Heroven, Christina; Šála, Michal; De Jonghe, Steven; Knapp, Stefan; Einav, Shirit; Herdewijn, Piet

    2015-04-23

    Cyclin G associated kinase (GAK) emerged as a promising drug target for the treatment of viral infections. However, no potent and selective GAK inhibitors have been reported in the literature to date. This paper describes the discovery of isothiazolo[5,4-b]pyridines as selective GAK inhibitors, with the most potent congeners displaying low nanomolar binding affinity for GAK. Cocrystallization experiments revealed that these compounds behaved as classic type I ATP-competitive kinase inhibitors. In addition, we have demonstrated that these compounds exhibit a potent activity against hepatitis C virus (HCV) by inhibiting two temporally distinct steps in the HCV life cycle (i.e., viral entry and assembly). Hence, these GAK inhibitors represent chemical probes to study GAK function in different disease areas where GAK has been implicated (including viral infection, cancer, and Parkinson's disease).

  5. Predicting the adsorption properties of carbon dioxide corrosion inhibitors using a structure-activity relationship

    Energy Technology Data Exchange (ETDEWEB)

    Kinsella, B.; De Marco, R.; Jefferson, A.; Pejcic, B. [Western Australian Corrosion Research Group, Department of Applied Chemistry, Curtin University of Technology, GPO Box U1987, Perth, 6845, WA (Australia); Durnie, W. [Nalco/Exxon Energy Chemicals Ltd, Hardley, Hythe, Southampton (Australia)

    2004-07-01

    This paper presents a study of the influence of various chemical inhibitors on the corrosion rate of mild steel in brine electrolyte under carbon dioxide conditions. The performances as corrosion inhibitors were fitted to a Temkin adsorption isotherm, and various constants of adsorption (i.e., adsorption equilibrium constants and molecular interaction constants) have been obtained. The inhibitor adsorption mechanism has been discussed in terms of thermodynamics (i.e., {delta}H, {delta}G and {delta}S) and this revealed that some compounds chemisorbed onto the steel electrode. In addition, molecular modelling was undertaken using PCSPARTAN Plus and HyperChem Professional, and the various molecular parameters have been correlated with the thermodynamic adsorption properties of the inhibitors. A four-parameter fit for both negative and positive charged molecules is discussed. (authors)

  6. Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

    Energy Technology Data Exchange (ETDEWEB)

    Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin; Othman, Norinsan Kamil [School of Applied Physic, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2014-09-03

    Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm. Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.

  7. Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

    Science.gov (United States)

    Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin; Othman, Norinsan Kamil

    2014-09-01

    Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm. Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.

  8. What determines the inhibition effectiveness of ATA, BTAH, and BTAOH corrosion inhibitors on copper?

    Science.gov (United States)

    Kokalj, Anton; Peljhan, Sebastijan; Finsgar, Matjaz; Milosev, Ingrid

    2010-11-24

    Three corrosion inhibitors for copper-3-amino-1,2,4-triazole (ATA), benzotriazole (BTAH), and 1-hydroxybenzotriazole (BTAOH)-were investigated by corrosion experiments and atomistic computer simulations. The trend of corrosion inhibition effectiveness of the three inhibitors on copper in near-neutral chloride solution is determined experimentally as BTAH ≳ ATA ≫ BTAOH. A careful analysis of the results of computer simulations based on density functional theory allowed to pinpoint the superior inhibiting action of BTAH and ATA as a result of their ability to form strong N-Cu chemical bonds in deprotonated form. While these bonds are not as strong as the Cl-Cu bonds, the presence of solvent favors the adsorption of inhibitor molecules onto the surface due to stronger solvation of the Cl(-) anions. Moreover, benzotriazole displays the largest affinity among the three inhibitors to form intermolecular aggregates, such as [BTA-Cu](n) polymeric complex. This is another factor contributing to the stability of the protective inhibitor film on the surface, thus making benzotriazole an outstanding corrosion inhibitor for copper. These findings cannot be anticipated on the basis of inhibitors' molecular electronic properties alone, thus emphasizing the importance of a rigorous modeling of the interactions between the components of the corrosion system in corrosion inhibition studies.

  9. Inhibition Performance of Enhanced-Mo Inhibitor for Carbon Steel in 55% LiBr Solution

    Institute of Scientific and Technical Information of China (English)

    LIANG Cheng-hao; HU Xian-qi

    2008-01-01

    The inhibition performance of enhanced-Mo inhibitor for carbon steel in 55% LiBr solution was measured by means of chemical immersion, electrochemical measurements, and physical detection technologies. Results indicated that enhanced-Mo inhibitor showed excellent inhibition performance of carbon steel in 55% LiBr solution, especially at high temperature. With increasing the temperature of solution from 160 ℃ to 240 ℃, the corrosion rates of carbon steel increased from 17.67 μm/a to 33.07 μm/a. Enhanced-Mo inhibitor might improve the anodic polarization performance of carbon steel and widen the passive potential region of carbon steel in 55% LiBr solution. Enhanced-Mo inhibitor belongs to anodic inhibitor. In 55% LiBr solution, the relationship between corrosion current density icorr and corrosion potential Ecorr of carbon steel accorded with the equation lgicorr=-2.66-3.54Ecorr, and the value of cathodic Tafel constant βc for the H2 reaction was 282 mVSCE. When 55% LiBr solution contained enhanced-Mo inhibitor, a passive film comprising Fe3O4 and MoO2 was formed on the carbon steel surface by electrochemical reactions. The corrosion of carbon steel might be retarded by this protective film, and the anticorrosion performance of carbon steel in 55% LiBr solution might be improved by enhanced-Mo inhibitor.

  10. Evolution of cyclic peptide protease inhibitors.

    Science.gov (United States)

    Young, Travis S; Young, Douglas D; Ahmad, Insha; Louis, John M; Benkovic, Stephen J; Schultz, Peter G

    2011-07-05

    We report a bacterial system for the evolution of cyclic peptides that makes use of an expanded set of amino acid building blocks. Orthogonal aminoacyl-tRNA synthetase/tRNA(CUA) pairs, together with a split intein system were used to biosynthesize a library of ribosomal peptides containing amino acids with unique structures and reactivities. This peptide library was subsequently used to evolve an inhibitor of HIV protease using a selection based on cellular viability. Two of three cyclic peptides isolated after two rounds of selection contained the keto amino acid p-benzoylphenylalanine (pBzF). The most potent peptide (G12: GIXVSL; X=pBzF) inhibited HIV protease through the formation of a covalent Schiff base adduct of the pBzF residue with the ε-amino group of Lys 14 on the protease. This result suggests that an expanded genetic code can confer an evolutionary advantage in response to selective pressure. Moreover, the combination of natural evolutionary processes with chemically biased building blocks provides another strategy for the generation of biologically active peptides using microbial systems.

  11. Fatty acid synthase inhibitors isolated from Punica granatum L

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, He-Zhong [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, (China); Ma, Qing-Yun; Liang, Wen-Juan; Huang, Sheng-Zhuo; Dai, Hao-Fu; Wang, Peng-Cheng; Zhao, You-Xing, E-mail: zhaoyx1011@163.com [Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou (China); Fan, Hui-Jin; Ma, Xiao-Feng, E-mail: maxiaofeng@gucas.ac.cn [College of Life Sciences, Graduate University of Chinese Academy of Sciences, Beijing (China)

    2012-05-15

    The aim of this work is the isolation of fatty acid synthase (FAS) inhibitors from the ethyl acetate extracts of fruit peels of Punica granatum L. Bioassay-guided chemical investigation of the fruit peels resulted in the isolation of seventeen compounds mainly including triterpenoids and phenolic compounds, from which one new oleanane-type triterpene (punicaone) along with fourteen known compounds were isolated for the first time from this plant. Seven isolates were evaluated for inhibitory activities of FAS and two compounds showed to be active. Particularly, flavogallonic acid exhibited strong FAS inhibitory activity with IC{sub 50} value of 10.3 {mu}mol L{sup -1}. (author)

  12. Neuraminidase Inhibitors from the Culture Broth of Phellinus linteus.

    Science.gov (United States)

    Yeom, Ji-Hee; Lee, In-Kyoung; Ki, Dae-Won; Lee, Myeong-Seok; Seok, Soon-Ja; Yun, Bong-Sik

    2012-06-01

    During the search for neuraminidase inhibitors from medicinal fungi, we found that the culture broth of Phellinus linteus exhibited potent inhibitory activity. Solvent partition, Sephadex LH-20 column chromatography, and high-performance liquid chromatography (HPLC) were performed for purification of two active substances from the culture broth. According to (1)H NMR measurements and comparison of HPLC retention times with those of authentic compounds, their chemical structures were identified as hispidin and hypholomine B. Compounds (hispidin) 1 and 2 (hypholomine B) inhibited neuraminidase, with IC(50) values of 13.1 and 0.03 µM, respectively.

  13. CHEMICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1965-06-01

    How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.

  14. Chemical information science coverage in Chemical Abstracts.

    Science.gov (United States)

    Wiggins, G

    1987-02-01

    For many years Chemical Abstracts has included in its coverage publications on chemical documentation or chemical information science. Although the bulk of those publications can be found in section 20 of Chemical Abstracts, many relevant articles were found scattered among 39 other sections of CA in 1984-1985. In addition to the scattering of references in CA, the comprehensiveness of Chemical Abstracts as a secondary source for chemical information science is called into question. Data are provided on the journals that contributed the most references on chemical information science and on the languages of publication of relevant articles.

  15. The potent Cdc7-Dbf4 (DDK kinase inhibitor XL413 has limited activity in many cancer cell lines and discovery of potential new DDK inhibitor scaffolds.

    Directory of Open Access Journals (Sweden)

    Nanda Kumar Sasi

    Full Text Available Cdc7-Dbf4 kinase or DDK (Dbf4-dependent kinase is required to initiate DNA replication by phosphorylating and activating the replicative Mcm2-7 DNA helicase. DDK is overexpressed in many tumor cells and is an emerging chemotherapeutic target since DDK inhibition causes apoptosis of diverse cancer cell types but not of normal cells. PHA-767491 and XL413 are among a number of potent DDK inhibitors with low nanomolar IC50 values against the purified kinase. Although XL413 is highly selective for DDK, its activity has not been extensively characterized on cell lines. We measured anti-proliferative and apoptotic effects of XL413 on a panel of tumor cell lines compared to PHA-767491, whose activity is well characterized. Both compounds were effective biochemical DDK inhibitors but surprisingly, their activities in cell lines were highly divergent. Unlike PHA-767491, XL413 had significant anti-proliferative activity against only one of the ten cell lines tested. Since XL413 did not effectively inhibit DDK in multiple cell lines, this compound likely has limited bioavailability. To identify potential leads for additional DDK inhibitors, we also tested the cross-reactivity of ∼400 known kinase inhibitors against DDK using a DDK thermal stability shift assay (TSA. We identified 11 compounds that significantly stabilized DDK. Several inhibited DDK with comparable potency to PHA-767491, including Chk1 and PKR kinase inhibitors, but had divergent chemical scaffolds from known DDK inhibitors. Taken together, these data show that several well-known kinase inhibitors cross-react with DDK and also highlight the opportunity to design additional specific, biologically active DDK inhibitors for use as chemotherapeutic agents.

  16. The potent Cdc7-Dbf4 (DDK) kinase inhibitor XL413 has limited activity in many cancer cell lines and discovery of potential new DDK inhibitor scaffolds.

    Science.gov (United States)

    Sasi, Nanda Kumar; Tiwari, Kanchan; Soon, Fen-Fen; Bonte, Dorine; Wang, Tong; Melcher, Karsten; Xu, H Eric; Weinreich, Michael

    2014-01-01

    Cdc7-Dbf4 kinase or DDK (Dbf4-dependent kinase) is required to initiate DNA replication by phosphorylating and activating the replicative Mcm2-7 DNA helicase. DDK is overexpressed in many tumor cells and is an emerging chemotherapeutic target since DDK inhibition causes apoptosis of diverse cancer cell types but not of normal cells. PHA-767491 and XL413 are among a number of potent DDK inhibitors with low nanomolar IC50 values against the purified kinase. Although XL413 is highly selective for DDK, its activity has not been extensively characterized on cell lines. We measured anti-proliferative and apoptotic effects of XL413 on a panel of tumor cell lines compared to PHA-767491, whose activity is well characterized. Both compounds were effective biochemical DDK inhibitors but surprisingly, their activities in cell lines were highly divergent. Unlike PHA-767491, XL413 had significant anti-proliferative activity against only one of the ten cell lines tested. Since XL413 did not effectively inhibit DDK in multiple cell lines, this compound likely has limited bioavailability. To identify potential leads for additional DDK inhibitors, we also tested the cross-reactivity of ∼400 known kinase inhibitors against DDK using a DDK thermal stability shift assay (TSA). We identified 11 compounds that significantly stabilized DDK. Several inhibited DDK with comparable potency to PHA-767491, including Chk1 and PKR kinase inhibitors, but had divergent chemical scaffolds from known DDK inhibitors. Taken together, these data show that several well-known kinase inhibitors cross-react with DDK and also highlight the opportunity to design additional specific, biologically active DDK inhibitors for use as chemotherapeutic agents.

  17. Nature's chemicals and synthetic chemicals: comparative toxicology.

    OpenAIRE

    Ames, B N; Profet, M; Gold, L S

    1990-01-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in brocco...

  18. Tissue factor pathway inhibitor endocytosis.

    Science.gov (United States)

    Schwartz, A L; Broze, G J

    1997-10-01

    Tissue factor pathway inhibitor (TFPI), a 42 kD protein, provides the physiological inhibition of tissue factor initiated coagulation by inhibition of both factor Xa and factor VIIa/tissue factor. In plasma, most TFPI is lipoprotein bound with an additional "releasable" pool bound to the endothelial cell surface. TFPI clearance is via receptor mediated endocytosis into liver. Heparin sulfate proteoglycans and LRP (low density lipoprotein receptor-related protein), an extremely large (∼600 kD) cell surface protein, primarily mediate this clearance, although additional TFPI binding sites and endocytosis pathways exist. (Trends Cardiovasc Med 1997; 7:234-239). © 1997, Elsevier Science Inc.

  19. Development of a Method for Converting a TAK1 Type I Inhibitor into a Type II or c-Helix-Out Inhibitor by Structure-Based Drug Design (SBDD).

    Science.gov (United States)

    Muraoka, Terushige; Ide, Mitsuaki; Irie, Machiko; Morikami, Kenji; Miura, Takaaki; Nishihara, Masamichi; Kashiwagi, Hirotaka

    2016-01-01

    We have developed a method for converting a transforming growth factor-β-activated kinase 1 (TAK1) type I inhibitor into a type II or c-helix-out inhibitor by structure-based drug design (SBDD) to achieve an effective strategy for developing these different types of kinase inhibitor in parallel. TAK1 plays a key role in inflammatory and immune signaling, and is therefore considered to be an attractive molecular target for the treatment of human diseases (inflammatory disease, cancer, etc.). We have already reported novel type I TAK1 inhibitor, so we utilized its X-ray information to design a new chemical class type II and c-helix-out inhibitors. To develop the type II inhibitor, we superimposed the X-ray structure of our reported type I inhibitor onto a type II compound that inhibits multiple kinases, and used SBDD to design a new type II inhibitor. For the TAK1 c-helix-out inhibitor, we utilized the X-ray structure of a b-Raf c-helix-out inhibitor to design compounds, because TAK1 is located close to b-Raf in the Sugen kinase tree, so we considered that TAK1 would, similarly to b-Raf, form a c-helix-out conformation. The X-ray crystal structure of the inhibitors in complex with TAK1 confirmed the binding modes of the compounds we designed. This report is notable for being the first discovery of a c-helix-out inhibitor against TAK1.

  20. American Chemical Society--238th National Meeting & Exposition. Developments in medicinal chemistry: part 2. 16-20 August 2009, Washington DC, USA.

    Science.gov (United States)

    Gater, Deborah; Macauley, Donald

    2009-10-01

    The 238th National Meeting and Exposition of the American Chemical Society, held in Washington DC, included topics covering new compounds and developments in the field of medicinal chemistry. This conference report highlights selected presentations on inhibitors of PARP, a heme oxygenase 1 (HO-1) inhibitor, NS3 protease inhibitors, a corticotrophin-releasing factor 1 (CRF-1) receptor antagonist, a cannabinoid receptor antagonist, diacylglycerol acyltransferase inhibitors, cathepsin and chymase receptor inhibitors, and MAPK inhibitors. Investigational drugs discussed include veliparib (Abbott Laboratories), MK-4827 (Merck & Co Inc), OB-24 (Osta Biotechnologies), BMS-339, BMS-764459, BMS-812204 and BMS-640994 (all Bristol-Myers Squibb Co), and JNJ-10311795 (Johnson & Johnson).

  1. A new class of small molecule inhibitor of BMP signaling.

    Directory of Open Access Journals (Sweden)

    Caroline E Sanvitale

    Full Text Available Growth factor signaling pathways are tightly regulated by phosphorylation and include many important kinase targets of interest for drug discovery. Small molecule inhibitors of the bone morphogenetic protein (BMP receptor kinase ALK2 (ACVR1 are needed urgently to treat the progressively debilitating musculoskeletal disease fibrodysplasia ossificans progressiva (FOP. Dorsomorphin analogues, first identified in zebrafish, remain the only BMP inhibitor chemotype reported to date. By screening an assay panel of 250 recombinant human kinases we identified a highly selective 2-aminopyridine-based inhibitor K02288 with in vitro activity against ALK2 at low nanomolar concentrations similar to the current lead compound LDN-193189. K02288 specifically inhibited the BMP-induced Smad pathway without affecting TGF-β signaling and induced dorsalization of zebrafish embryos. Comparison of the crystal structures of ALK2 with K02288 and LDN-193189 revealed additional contacts in the K02288 complex affording improved shape complementarity and identified the exposed phenol group for further optimization of pharmacokinetics. The discovery of a new chemical series provides an independent pharmacological tool to investigate BMP signaling and offers multiple opportunities for pre-clinical development.

  2. Developmental defects in zebrafish for classification of EGF pathway inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Pruvot, Benoist; Curé, Yoann; Djiotsa, Joachim; Voncken, Audrey; Muller, Marc, E-mail: m.muller@ulg.ac.be

    2014-01-15

    One of the major challenges when testing drug candidates targeted at a specific pathway in whole animals is the discrimination between specific effects and unwanted, off-target effects. Here we used the zebrafish to define several developmental defects caused by impairment of Egf signaling, a major pathway of interest in tumor biology. We inactivated Egf signaling by genetically blocking Egf expression or using specific inhibitors of the Egf receptor function. We show that the combined occurrence of defects in cartilage formation, disturbance of blood flow in the trunk and a decrease of myelin basic protein expression represent good indicators for impairment of Egf signaling. Finally, we present a classification of known tyrosine kinase inhibitors according to their specificity for the Egf pathway. In conclusion, we show that developmental indicators can help to discriminate between specific effects on the target pathway from off-target effects in molecularly targeted drug screening experiments in whole animal systems. - Highlights: • We analyze the functions of Egf signaling on zebrafish development. • Genetic blocking of Egf expression causes cartilage, myelin and circulatory defects. • Chemical inhibition of Egf receptor function causes similar defects. • Developmental defects can reveal the specificity of Egf pathway inhibitors.

  3. Autophagy inhibitors as a potential antiamoebic treatment for Acanthamoeba keratitis.

    Science.gov (United States)

    Moon, Eun-Kyung; Kim, So-Hee; Hong, Yeonchul; Chung, Dong-Il; Goo, Youn-Kyoung; Kong, Hyun-Hee

    2015-07-01

    Acanthamoeba cysts are resistant to extreme physical and chemical conditions. Autophagy is an essential pathway for encystation of Acanthamoeba cells. To evaluate the possibility of an autophagic Acanthamoeba encystation mechanism, we evaluated autophagy inhibitors, such as 3-methyladenine (3MA), LY294002, wortmannin, bafilomycin A, and chloroquine. Among these autophagy inhibitors, the use of 3MA and chloroquine showed a significant reduction in the encystation ratio in Acanthamoeba cells. Wortmannin also inhibited the formation of mature cysts, while LY294002 and bafilomycin A did not affect the encystation of Acanthamoeba cells. Transmission electron microscopy revealed that 3MA and wortmannin inhibited autophagy formation and that chloroquine interfered with the formation of autolysosomes. Inhibition of autophagy or autolysosome formation resulted in a significant block in the encystation in Acanthamoeba cells. Clinical treatment with 0.02% polyhexamethylene biguanide (PHMB) showed high cytopathic effects on Acanthamoeba trophozoites and cysts; however, it also revealed high cytopathic effects on human corneal epithelial cells. In this study, we investigated effects of the combination of a low (0.00125%) concentration of PHMB with each of the autophagy inhibitors 3MA, wortmannin, and chloroquine on Acanthamoeba and human corneal epithelial cells. These new combination treatments showed low cytopathic effects on human corneal cells and high cytopathic effects on Acanthamoeba cells. Taken together, these results provide fundamental information for optimizing the treatment of Acanthamoeba keratitis.

  4. Effect of FGFR inhibitors on chicken limb development.

    Science.gov (United States)

    Horakova, Dana; Cela, Petra; Krejci, Pavel; Balek, Lukas; Moravcova Balkova, Simona; Matalova, Eva; Buchtova, Marcela

    2014-10-01

    Fibroblast growth factor (FGF) signalling appears essential for the regulation of limb development, but a full complexity of this regulation remains unclear. Here, we addressed the effect of three different chemical inhibitors of FGF receptor tyrosine kinases (FGFR) on growth and patterning of the chicken wings. The inhibitor PD173074 caused shorter and thinner wing when using lower concentration. Microinjection of higher PD173074 concentrations (25 and 50 mmol/L) into the wing bud at stage 20 resulted in the development of small wing rudiment or the total absence of the wing. Skeletal analysis revealed the absence of the radius but not ulna, deformation of metacarpal bones and/or a reduction of digits. Treatment with PD161570 resembled the effects of PD173074. NF449 induced shortening and deformation of the developing wing with reduced autopodium. These malformed embryos mostly died at the stage HH25-29. PD173074 reduced chondrogenesis also in the limb micromass cultures together with early inhibition of cartilaginous nodule formation, evidenced by lack of sulphated proteoglycan and peanut agglutinin expression. The effect of FGFR inhibition on limb development observed here was unlikely mediated by excessive cell death as none of the inhibitors caused massive apoptosis at low concentrations. More probably, FGFR inhibition decreased both the proliferation and adhesion of mesenchymal chondroprogenitors. We conclude that FGFR signalling contributes to the regulation of the anterior-posterior patterning of zeugopod during chicken limb development.

  5. Identification of covalent active site inhibitors of dengue virus protease

    Directory of Open Access Journals (Sweden)

    Koh-Stenta X

    2015-12-01

    Full Text Available Xiaoying Koh-Stenta,1 Joma Joy,1 Si Fang Wang,1 Perlyn Zekui Kwek,1 John Liang Kuan Wee,1 Kah Fei Wan,2 Shovanlal Gayen,1 Angela Shuyi Chen,1 CongBao Kang,1 May Ann Lee,1 Anders Poulsen,1 Subhash G Vasudevan,3 Jeffrey Hill,1 Kassoum Nacro11Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR, Singapore; 2Novartis Institute for Tropical Diseases, Singapore; 3Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, SingaporeAbstract: Dengue virus (DENV protease is an attractive target for drug development; however, no compounds have reached clinical development to date. In this study, we utilized a potent West Nile virus protease inhibitor of the pyrazole ester derivative class as a chemical starting point for DENV protease drug development. Compound potency and selectivity for DENV protease were improved through structure-guided small molecule optimization, and protease-inhibitor binding interactions were validated biophysically using nuclear magnetic resonance. Our work strongly suggests that this class of compounds inhibits flavivirus protease through targeted covalent modification of active site serine, contrary to an allosteric binding mechanism as previously described.Keywords: flavivirus protease, small molecule optimization, covalent inhibitor, active site binding, pyrazole ester derivatives

  6. Thermodynamics and kinetics of inhibitor binding to human equilibrative nucleoside transporter subtype-1.

    Science.gov (United States)

    Rehan, Shahid; Ashok, Yashwanth; Nanekar, Rahul; Jaakola, Veli-Pekka

    2015-12-15

    Many nucleoside transport inhibitors are in clinical use as anti-cancer, vasodilator and cardioprotective drugs. However, little is known about the binding energetics of these inhibitors to nucleoside transporters (NTs) due to their low endogenous expression levels and difficulties in the biophysical characterization of purified protein with ligands. Here, we present kinetics and thermodynamic analyses of inhibitor binding to the human equilibrative nucleoside transporter-1 (hENT1), also known as SLC29A1. Using a radioligand binding assay, we obtained equilibrium binding and kinetic rate constants of well-known NT inhibitors--[(3)H]nitrobenzylmercaptopurine ribonucleoside ([(3)H]NBMPR), dilazep, and dipyridamole--and the native permeant, adenosine, to hENT1. We observed that the equilibrium binding affinities for all inhibitors decreased whereas, the kinetic rate constants increased with increasing temperature. Furthermore, we found that binding is enthalpy driven and thus, an exothermic reaction, implying that the transporter does not discriminate between its inhibitors and substrates thermodynamically. This predominantly enthalpy-driven binding by four chemically distinct ligands suggests that the transporter may not tolerate diversity in the type of interactions that lead to high affinity binding. Consistent with this, the measured activation energy of [(3)H]NBMPR association was relatively large (20 kcal mol(-1)) suggesting a conformational change upon inhibitor binding. For all three inhibitors the enthalpy (ΔH°) and entropy (ΔS°) contributions to the reaction energetics were determined by van't Hoff analysis to be roughly similar (25-75% ΔG°). Gains in enthalpy with increasing polar surface area of inhibitors suggest that the binding is favored by electrostatic or polar interactions between the ligands and the transporter.

  7. Allosteric inhibitors of inducible nitric oxide synthase dimerization discovered via combinatorial chemistry

    Science.gov (United States)

    McMillan, Kirk; Adler, Marc; Auld, Douglas S.; Baldwin, John J.; Blasko, Eric; Browne, Leslie J.; Chelsky, Daniel; Davey, David; Dolle, Ronald E.; Eagen, Keith A.; Erickson, Shawn; Feldman, Richard I.; Glaser, Charles B.; Mallari, Cornell; Morrissey, Michael M.; Ohlmeyer, Michael H. J.; Pan, Gonghua; Parkinson, John F.; Phillips, Gary B.; Polokoff, Mark A.; Sigal, Nolan H.; Vergona, Ronald; Whitlow, Marc; Young, Tish A.; Devlin, James J.

    2000-01-01

    Potent and selective inhibitors of inducible nitric oxide synthase (iNOS) (EC 1.14.13.39) were identified in an encoded combinatorial chemical library that blocked human iNOS dimerization, and thereby NO production. In a cell-based iNOS assay (A-172 astrocytoma cells) the inhibitors had low-nanomolar IC50 values and thus were >1,000-fold more potent than the substrate-based direct iNOS inhibitors 1400W and N-methyl-l-arginine. Biochemical studies confirmed that inhibitors caused accumulation of iNOS monomers in mouse macrophage RAW 264.7 cells. High affinity (Kd ≈ 3 nM) of inhibitors for isolated iNOS monomers was confirmed by using a radioligand binding assay. Inhibitors were >1,000-fold selective for iNOS versus endothelial NOS dimerization in a cell-based assay. The crystal structure of inhibitor bound to the monomeric iNOS oxygenase domain revealed inhibitor–heme coordination and substantial perturbation of the substrate binding site and the dimerization interface, indicating that this small molecule acts by allosterically disrupting protein–protein interactions at the dimer interface. These results provide a mechanism-based approach to highly selective iNOS inhibition. Inhibitors were active in vivo, with ED50 values of <2 mg/kg in a rat model of endotoxin-induced systemic iNOS induction. Thus, this class of dimerization inhibitors has broad therapeutic potential in iNOS-mediated pathologies. PMID:10677491

  8. Development of an environmentally friendly combined scale/corrosion inhibitor for subsea application

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Alyn [M-I SWACO, Houston, TX (United States)

    2009-07-01

    In many offshore oil and gas fields, production chemicals are required to be applied subsea to mitigate the common flow assurance problems that are present either in the well or subsea gathering and flow lines. Common flow assurance issues include scale, hydrate formation, corrosion and also wax deposition. For subsea systems, production chemicals are applied either at the subsea wellhead, flow lines or downhole. However, for many fields there are an inadequate number of chemical umbilicals, chemical injection pumps or chemical storage tanks. Consequently, there is a strong requirement for combination or multifunctional products that help to minimize the amount of chemical injection equipment needed. This paper describes the work involved in developing an environmentally acceptable combined scale/corrosion inhibitor for deployment in subsea pipelines in a UK North Sea oil field. The paper details the laboratory testing performed and includes corrosion field data that has been used to confirm product performance. (author)

  9. Aromatase inhibitors and bone loss.

    Science.gov (United States)

    Perez, Edith A; Weilbaecher, Katherine

    2006-08-01

    The aromatase inhibitors (AIs) anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin) are significantly more effective than the selective estrogen-receptor modulator (SERM) tamoxifen in preventing recurrence in estrogen receptor-positive early breast cancer. Aromatase inhibitors are likely to replace SERMs as first-line adjuvant therapy for many patients. However, AIs are associated with significantly more osteoporotic fractures and greater bone mineral loss. As antiresorptive agents, oral and intravenous bisphosphonates such as alendronate (Fosamax), risedronate (Actonel), ibandronate (Boniva), pamidronate (Aredia), and zoledronic acid (Zometa) have efficacy in preventing postmenopausal osteoporosis, cancer treatment-related bone loss, or skeletal complications of metastatic disease. Clinical practice guidelines recommend baseline and annual follow-up bone density monitoring for all patients initiating AI therapy. Bisphosphonate therapy should be prescribed for patients with osteoporosis (T score vitamin D intake, weight-bearing exercise, and smoking cessation should be addressed. Adverse events associated with bisphosphonates include gastrointestinal toxicity, renal toxicity, and osteonecrosis of the jaw. These safety concerns should be balanced with the potential of bisphosphonates to minimize or prevent the debilitating effects of AI-associated bone loss in patients with early, hormone receptor-positive breast cancer.

  10. Myeloperoxidase Inhibitors as Potential Drugs.

    Science.gov (United States)

    Lazarević-Pasti, Tamara; Leskovac, Andreja; Vasić, Vesna

    2015-01-01

    Myeloperoxidase (MPO) is an important member of the haem peroxidase - cyclooxygenase superfamily. This enzyme is physiologically expressed in circulating neutrophils, monocytes and some tissue macrophages including microglia. MPO plays an essential role in the antimicrobial and antiviral system of humans. The microbicidal activity of MPO exists due to its capability to oxidize halide and pseudohalide ions (CI(-), Br(-), I(-) and SCN(-)) by H2O2, thereby producing respective hypohalous acids (HOX). During the phagocytosis of pathogens, azurophilic granules release their content together with MPO into phagolysosomes. On the other hand, MPO can be discharged outside the phagocytes. Due to this, tissue damage during inflammation is greatly promoted by MPO-derived oxidants. Regarding its activity, MPO is a key factor in a great number of conditions within the group of cardiovascular diseases, inflammatory diseases, neurodegenerative diseases, kidney diseases and immune-mediated diseases. Therefore, MPO and its downstream inflammatory pathways might be attractive targets for both prognostic and therapeutic intervention in the prophylaxis of all mentioned illnesses. Nowadays, structure and reaction mechanism of MPO are known, which enable rational strategy in the development of specific MPO inhibitors that still preserve MPO activity during host defense from bacteria, but hinder pathophysiologically persistent activation of MPO. Various methods for MPO activity inhibition and unfavorable effects of MPO-derived oxidants remodeling will be discussed. Emphasis will be put on various known inhibitors, as well as on newly investigated natural products, which can also inhibit MPO activity.

  11. Proton pump inhibitors and osteoporosis

    DEFF Research Database (Denmark)

    Andersen, Bjarne Nesgaard; Johansen, Per Birger; Abrahamsen, Bo

    2016-01-01

    PURPOSE OF REVIEW: The purpose of the review is to provide an update on recent advances in the evidence based on proton pump inhibitors (PPI) as a possible cause of osteoporosis and osteoporotic fractures. This review focuses, in particular, on new studies published in the last 18 months and a di......PURPOSE OF REVIEW: The purpose of the review is to provide an update on recent advances in the evidence based on proton pump inhibitors (PPI) as a possible cause of osteoporosis and osteoporotic fractures. This review focuses, in particular, on new studies published in the last 18 months...... and a discussion of these findings and how this has influenced our understanding of this association, the clinical impact and the underlying pathophysiology. RECENT FINDINGS: New studies have further strengthened existing evidence linking use of PPIs to osteoporosis. Short-term use does not appear to pose a lower...... risk than long-term use. There is a continued lack of conclusive studies identifying the pathogenesis. Direct effects on calcium absorption or on osteoblast or osteoclast action cannot at present plausibly explain the mechanism. SUMMARY: The use of PPIs is a risk factor for development of osteoporosis...

  12. Inhibitor ranking through QM based chelation calculations for virtual screening of HIV-1 RNase H inhibition.

    Directory of Open Access Journals (Sweden)

    Vasanthanathan Poongavanam

    Full Text Available Quantum mechanical (QM calculations have been used to predict the binding affinity of a set of ligands towards HIV-1 RT associated RNase H (RNH. The QM based chelation calculations show improved binding affinity prediction for the inhibitors compared to using an empirical scoring function. Furthermore, full protein fragment molecular orbital (FMO calculations were conducted and subsequently analysed for individual residue stabilization/destabilization energy contributions to the overall binding affinity in order to better understand the true and false predictions. After a successful assessment of the methods based on the use of a training set of molecules, QM based chelation calculations were used as filter in virtual screening of compounds in the ZINC database. By this, we find, compared to regular docking, QM based chelation calculations to significantly reduce the large number of false positives. Thus, the computational models tested in this study could be useful as high throughput filters for searching HIV-1 RNase H active-site molecules in the virtual screening process.

  13. Rationally Designed Interfacial Peptides Are Efficient In Vitro Inhibitors of HIV-1 Capsid Assembly with Antiviral Activity

    OpenAIRE

    Rebeca Bocanegra; María Nevot; Rosa Doménech; Inmaculada López; Olga Abián; Alicia Rodríguez-Huete; Cavasotto, Claudio N.; Adrián Velázquez-Campoy; Javier Gómez; Miguel Ángel Martínez; José Luis Neira; Mateu, Mauricio G.

    2011-01-01

    Virus capsid assembly constitutes an attractive target for the development of antiviral therapies; a few experimental inhibitors of this process for HIV-1 and other viruses have been identified by screening compounds or by selection from chemical libraries. As a different, novel approach we have undertaken the rational design of peptides that could act as competitive assembly inhibitors by mimicking capsid structural elements involved in intersubunit interfaces. Several discrete interfaces in...

  14. Quantum chemical study on the corrosion inhibition property of some heterocyclic azole derivatives

    Directory of Open Access Journals (Sweden)

    N. Anusuya

    2015-09-01

    Full Text Available Quantum chemical calculations based on density functional theory (DFT method were performed on heterocyclic azole derivatives as corrosion inhibitors for mild steel in acid media to investigate the relationship between molecular structure of the inhibitors and the corresponding inhibition efficiencies (%. Quantum chemical parameters most relevant to their potential action as corrosion inhibitors have been calculated in the non-protonated and protonated forms in aqueous phase for comparison. Results obtained in this study indicate thatin acidic media, both the protonated and non-protonated forms of the azoles represent the better actual experimental situation.

  15. Investigation of some Schiff base compounds containing disulfide bond as HCl corrosion inhibitors for mild steel

    Energy Technology Data Exchange (ETDEWEB)

    Behpour, M., E-mail: m.behpour@kashanu.ac.i [Department of Chemistry, Faculty of Science, University of Kashan, Kashan (Iran, Islamic Republic of); Ghoreishi, S.M.; Mohammadi, N. [Department of Chemistry, Faculty of Science, University of Kashan, Kashan (Iran, Islamic Republic of); Soltani, N. [Payame Noor University (PNU), Shahin Shahr Branch, Isfahan (Iran, Islamic Republic of); Salavati-Niasari, M. [Department of Chemistry, Faculty of Science, University of Kashan, Kashan (Iran, Islamic Republic of)

    2010-12-15

    Research highlights: {yields} All studied Schiff bases are effective inhibitors for mild steel in 2.0 M HCl. {yields} The inhibition is accomplished by adsorption of molecules on the steel surface. {yields} Examined Schiff bases behave as mixed type inhibitor. {yields} Feed back bonds form between the Schiff bases and steel surface. {yields} Quantum chemical calculations were applied to explain the experimental results. - Abstract: The inhibition performance of three Schiff bases containing disulfide bond as corrosion inhibitors for mild steel in 2.0 M HCl has been investigated by weight loss measurements, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization study showed that all the inhibitors are mixed type. The adsorption of inhibitors on mild steel surface was found to follow Langmuir adsorption isotherm and the adsorption isotherm parameters (K{sub ads}, {Delta}G{sub ads}) were determined. Quantum chemical calculations were further applied to reveal the adsorption structure and explain the experimental results. Some samples of mild steel were examined by SEM.

  16. Small-molecule auxin inhibitors that target YUCCA are powerful tools for studying auxin function.

    Science.gov (United States)

    Kakei, Yusuke; Yamazaki, Chiaki; Suzuki, Masashi; Nakamura, Ayako; Sato, Akiko; Ishida, Yosuke; Kikuchi, Rie; Higashi, Shouichi; Kokudo, Yumiko; Ishii, Takahiro; Soeno, Kazuo; Shimada, Yukihisa

    2015-11-01

    Auxin is essential for plant growth and development, this makes it difficult to study the biological function of auxin using auxin-deficient mutants. Chemical genetics have the potential to overcome this difficulty by temporally reducing the auxin function using inhibitors. Recently, the indole-3-pyruvate (IPyA) pathway was suggested to be a major biosynthesis pathway in Arabidopsis thaliana L. for indole-3-acetic acid (IAA), the most common member of the auxin family. In this pathway, YUCCA, a flavin-containing monooxygenase (YUC), catalyzes the last step of conversion from IPyA to IAA. In this study, we screened effective inhibitors, 4-biphenylboronic acid (BBo) and 4-phenoxyphenylboronic acid (PPBo), which target YUC. These compounds inhibited the activity of recombinant YUC in vitro, reduced endogenous IAA content, and inhibited primary root elongation and lateral root formation in wild-type Arabidopsis seedlings. Co-treatment with IAA reduced the inhibitory effects. Kinetic studies of BBo and PPBo showed that they are competitive inhibitors of the substrate IPyA. Inhibition constants (Ki ) of BBo and PPBo were 67 and 56 nm, respectively. In addition, PPBo did not interfere with the auxin response of auxin-marker genes when it was co-treated with IAA, suggesting that PPBo is not an inhibitor of auxin sensing or signaling. We propose that these compounds are a class of auxin biosynthesis inhibitors that target YUC. These small molecules are powerful tools for the chemical genetic analysis of auxin function.

  17. Urearetics: a small molecule screen yields nanomolar potency inhibitors of urea transporter UT-B.

    Science.gov (United States)

    Levin, Marc H; de la Fuente, Ricardo; Verkman, A S

    2007-02-01

    Functional studies in knockout mice indicate a critical role for urea transporters (UTs) in the urinary concentrating mechanism and in renal urea clearance. However, potent and specific urea transport blockers have not been available. Here, we used high-throughput screening to discover high-affinity, small molecule inhibitors of the UT-B urea transporter. A collection of 50,000 diverse, drug-like compounds was screened using a human erythrocyte lysis assay based on UT-B-facilitated acetamide transport. Primary screening yielded approximately 30 UT-B inhibitors belonging to the phenylsulfoxyoxazole, benzenesulfonanilide, phthalazinamine, and aminobenzimidazole chemical classes. Screening of approximately 700 structurally similar analogs gave many active compounds, the most potent of which inhibited UT-B urea transport with an EC50 of approximately 10 nM, and approximately 100% inhibition at higher concentrations. Phenylsulfoxyoxazoles and phthalazinamines also blocked rodent UT-B and had good UT-B vs. UT-A specificity. The UT-B inhibitors did not reduce aquaporin-1 (AQP1)-facilitated water transport. In AQP1-null erythrocytes, "chemical UT-B knockout" by UT-B inhibitors reduced by approximately 3-fold UT-B-mediated water transport, supporting an aqueous pore pathway through UT-B. UT-B inhibitors represent a new class of diuretics, "urearetics," which are predicted to increase renal water and solute clearance in water-retaining states.

  18. Exploring the problem of mold growth and the efficacy of various mold inhibitor methods during moisture sorption isotherm measurements.

    Science.gov (United States)

    Yu, X; Martin, S E; Schmidt, S J

    2008-03-01

    Mold growth is a common problem during the equilibration of food materials at high relative humidity values using the standard saturated salt slurry method. Exposing samples to toluene vapor and mixing samples with mold inhibitor chemicals are suggested methods for preventing mold growth while obtaining isotherms. However, no published research was found that examined the effect of mold growth on isotherm performance or the efficacy of various mold inhibitor methods, including their possible effect on the physicochemical properties of food materials. Therefore, the objectives of this study were to (1) explore the effect of mold growth on isotherm performance in a range of food materials, (2) investigate the effectiveness of 4 mold inhibitor methods, irradiation, 2 chemical inhibitors (potassium sorbate and sodium acetate), and toluene vapor, on mold growth on dent corn starch inoculated with A. niger, and (3) examine the effect of mold inhibitor methods on the physicochemical properties of dent corn starch, including isotherm performance, pasting properties, gelatinization temperature, and enthalpy. Mold growth was found to affect starch isotherm performance by contributing to weight changes during sample equilibration. Among the 4 mold inhibitor methods tested, irradiation and toluene vapor were found to be the most effective for inhibiting growth of A. niger on dent cornstarch. However, both methods exhibited a significant impact on the starches' physiochemical properties, suggesting the need to probe the efficacy of other mold inhibitor methods and explore the use of new rapid isotherm instruments, which hamper mold growth by significantly decreasing measurement time.

  19. Metabolically Labile Fumarate Esters Impart Kinetic Selectivity to Irreversible Inhibitors.

    Science.gov (United States)

    Zaro, Balyn W; Whitby, Landon R; Lum, Kenneth M; Cravatt, Benjamin F

    2016-12-14

    Electrophilic small molecules are an important class of chemical probes and drugs that produce biological effects by irreversibly modifying proteins. Examples of electrophilic drugs include covalent kinase inhibitors that are used to treat cancer and the multiple sclerosis drug dimethyl fumarate. Optimized covalent drugs typically inactivate their protein targets rapidly in cells, but ensuing time-dependent, off-target protein modification can erode selectivity and diminish the utility of reactive small molecules as chemical probes and therapeutics. Here, we describe an approach to confer kinetic selectivity to electrophilic drugs. We show that an analogue of the covalent Bruton's tyrosine kinase (BTK) inhibitor Ibrutinib bearing a fumarate ester electrophile is vulnerable to enzymatic metabolism on a time-scale that preserves rapid and sustained BTK inhibition, while thwarting more slowly accumulating off-target reactivity in cell and animal models. These findings demonstrate that metabolically labile electrophilic groups can endow covalent drugs with kinetic selectivity to enable perturbation of proteins and biochemical pathways with greater precision.

  20. Structure-based design and synthesis of pyrazinones containing novel P1 'side pocket' moieties as inhibitors of TF/VIIa.

    Science.gov (United States)

    Schweitzer, Barbara A; Neumann, William L; Rahman, Hayat K; Kusturin, Carrie L; Sample, Kirby R; Poda, Gennadiy I; Kurumbail, Ravi G; Stevens, Anna M; Stegeman, Roderick A; Stallings, William C; South, Michael S

    2005-06-15

    We describe the structure-based design, synthesis, and enzymatic activity of a series of substituted pyrazinones as inhibitors of the TF/VIIa complex. These inhibitors contain substituents meta to the P(1) amidine designed to explore additional interactions with the VIIa residues in the so-called 'S(1) side pocket'. A crystal structure of the designed inhibitors demonstrates the ability of the P(1) side pocket moiety to engage Lys192 and main chain of Gly216 via hydrogen bond interactions, thus, providing additional possibility for chemical modification to improve selectivity and/or physical properties of inhibitors.

  1. HDACiDB: a database for histone deacetylase inhibitors

    Directory of Open Access Journals (Sweden)

    Murugan K

    2015-04-01

    Full Text Available Kasi Murugan,1 Shanmugasamy Sangeetha,2 Shanmugasamy Ranjitha,2 Antony Vimala,2 Saleh Al-Sohaibani,1 Gopal Rameshkumar21Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia; 2Bioinformatics Laboratory, Anna University K. Balachander Research Centre, MIT Campus of Anna University Chennai, Chennai, IndiaAbstract: An histone deacetylase (HDAC inhibitor database (HDACiDB was constructed to enable rapid access to data relevant to the development of epigenetic modulators (HDAC inhibitors [HDACi], helping bring precision cancer medicine a step closer. Thousands of HDACi targeting HDACs are in various stages of development and are being tested in clinical trials as monotherapy and in combination with other cancer agents. Despite the abundance of HDACi, information resources are limited. Tools for in silico experiments on specific HDACi prediction, for designing and analyzing the generated data, as well as custom-made specific tools and interactive databases, are needed. We have developed an HDACiDB that is a composite collection of HDACi and currently comprises 1,445 chemical compounds, including 419 natural and 1,026 synthetic ones having the potential to inhibit histone deacetylation. Most importantly, it will allow application of Lipinski’s rule of five drug-likeness and other physicochemical property-based screening of the inhibitors. It also provides easy access to information on their source of origin, molecular properties, drug likeness, as well as bioavailability with relevant references cited. Being the first comprehensive database on HDACi that contains all known natural and synthetic HDACi, the HDACiDB may help to improve our knowledge concerning the mechanisms of actions of available HDACi and enable us to selectively target individual HDAC isoforms and establish a new paradigm for intelligent epigenetic cancer drug design. The database is freely available on the http

  2. Effects of Small Molecule Calcium-Activated Chloride Channel Inhibitors on Structure and Function of Accessory Cholera Enterotoxin (Ace of Vibrio cholerae.

    Directory of Open Access Journals (Sweden)

    Tanaya Chatterjee

    Full Text Available Cholera pathogenesis occurs due to synergistic pro-secretory effects of several toxins, such as cholera toxin (CTX and Accessory cholera enterotoxin (Ace secreted by Vibrio cholerae strains. Ace activates chloride channels stimulating chloride/bicarbonate transport that augments fluid secretion resulting in diarrhea. These channels have been targeted for drug development. However, lesser attention has been paid to the interaction of chloride channel modulators with bacterial toxins. Here we report the modulation of the structure/function of recombinant Ace by small molecule calcium-activated chloride channel (CaCC inhibitors, namely CaCCinh-A01, digallic acid (DGA and tannic acid. Biophysical studies indicate that the unfolding (induced by urea free energy increases upon binding CaCCinh-A01 and DGA, compared to native Ace, whereas binding of tannic acid destabilizes the protein. Far-UV CD experiments revealed that the α-helical content of Ace-CaCCinh-A01 and Ace-DGA complexes increased relative to Ace. In contrast, binding to tannic acid had the opposite effect, indicating the loss of protein secondary structure. The modulation of Ace structure induced by CaCC inhibitors was also analyzed using docking and molecular dynamics (MD simulation. Functional studies, performed using mouse ileal loops and Ussing chamber experiments, corroborate biophysical data, all pointing to the fact that tannic acid destabilizes Ace, inhibiting its function, whereas DGA stabilizes the toxin with enhanced fluid accumulation in mouse ileal loop. The efficacy of tannic acid in mouse model suggests that the targeted modulation of Ace structure may be of therapeutic benefit for gastrointestinal disorders.

  3. Effects of Small Molecule Calcium-Activated Chloride Channel Inhibitors on Structure and Function of Accessory Cholera Enterotoxin (Ace) of Vibrio cholerae

    Science.gov (United States)

    Chatterjee, Tanaya; Sheikh, Irshad Ali; Chakravarty, Devlina; Chakrabarti, Pinak; Sarkar, Paramita; Saha, Tultul; Chakrabarti, Manoj K.; Hoque, Kazi Mirajul

    2015-01-01

    Cholera pathogenesis occurs due to synergistic pro-secretory effects of several toxins, such as cholera toxin (CTX) and Accessory cholera enterotoxin (Ace) secreted by Vibrio cholerae strains. Ace activates chloride channels stimulating chloride/bicarbonate transport that augments fluid secretion resulting in diarrhea. These channels have been targeted for drug development. However, lesser attention has been paid to the interaction of chloride channel modulators with bacterial toxins. Here we report the modulation of the structure/function of recombinant Ace by small molecule calcium-activated chloride channel (CaCC) inhibitors, namely CaCCinh-A01, digallic acid (DGA) and tannic acid. Biophysical studies indicate that the unfolding (induced by urea) free energy increases upon binding CaCCinh-A01 and DGA, compared to native Ace, whereas binding of tannic acid destabilizes the protein. Far-UV CD experiments revealed that the α-helical content of Ace-CaCCinh-A01 and Ace-DGA complexes increased relative to Ace. In contrast, binding to tannic acid had the opposite effect, indicating the loss of protein secondary structure. The modulation of Ace structure induced by CaCC inhibitors was also analyzed using docking and molecular dynamics (MD) simulation. Functional studies, performed using mouse ileal loops and Ussing chamber experiments, corroborate biophysical data, all pointing to the fact that tannic acid destabilizes Ace, inhibiting its function, whereas DGA stabilizes the toxin with enhanced fluid accumulation in mouse ileal loop. The efficacy of tannic acid in mouse model suggests that the targeted modulation of Ace structure may be of therapeutic benefit for gastrointestinal disorders. PMID:26540279

  4. Artificial neural network cascade identifies multi-P450 inhibitors in natural compounds

    Directory of Open Access Journals (Sweden)

    Zhangming Li

    2015-12-01

    Full Text Available Substantial evidence has shown that most exogenous substances are metabolized by multiple cytochrome P450 (P450 enzymes instead of by merely one P450 isoform. Thus, multi-P450 inhibition leads to greater drug-drug interaction risk than specific P450 inhibition. Herein, we innovatively established an artificial neural network cascade (NNC model composed of 23 cascaded networks in a ladder-like framework to identify potential multi-P450 inhibitors among natural compounds by integrating 12 molecular descriptors into a P450 inhibition score (PIS. Experimental data reporting in vitro inhibition of five P450 isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 were obtained for 8,148 compounds from the Cytochrome P450 Inhibitors Database (CPID. The results indicate significant positive correlation between the PIS values and the number of inhibited P450 isoforms (Spearman’s ρ = 0.684, p < 0.0001. Thus, a higher PIS indicates a greater possibility for a chemical to inhibit the enzyme activity of at least three P450 isoforms. Ten-fold cross-validation of the NNC model suggested an accuracy of 78.7% for identifying whether a compound is a multi-P450 inhibitor or not. Using our NNC model, 22.2% of the approximately 160,000 natural compounds in TCM Database@Taiwan were identified as potential multi-P450 inhibitors. Furthermore, chemical similarity calculations suggested that the prevailing parent structures of natural multi-P450 inhibitors were alkaloids. Our findings show that dissection of chemical structure contributes to confident identification of natural multi-P450 inhibitors and provides a feasible method for virtually evaluating multi-P450 inhibition risk for a known structure.

  5. Identification and Structure-Function Analysis of Subfamily Selective G Protein-Coupled Receptor Kinase Inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Homan, Kristoff T.; Larimore, Kelly M.; Elkins, Jonathan M.; Szklarz, Marta; Knapp, Stefan; Tesmer, John J.G. [Michigan; (Oxford)

    2015-02-13

    Selective inhibitors of individual subfamilies of G protein-coupled receptor kinases (GRKs) would serve as useful chemical probes as well as leads for therapeutic applications ranging from heart failure to Parkinson’s disease. To identify such inhibitors, differential scanning fluorimetry was used to screen a collection of known protein kinase inhibitors that could increase the melting points of the two most ubiquitously expressed GRKs: GRK2 and GRK5. Enzymatic assays on 14 of the most stabilizing hits revealed that three exhibit nanomolar potency of inhibition for individual GRKs, some of which exhibiting orders of magnitude selectivity. Most of the identified compounds can be clustered into two chemical classes: indazole/dihydropyrimidine-containing compounds that are selective for GRK2 and pyrrolopyrimidine-containing compounds that potently inhibit GRK1 and GRK5 but with more modest selectivity. The two most potent inhibitors representing each class, GSK180736A and GSK2163632A, were cocrystallized with GRK2 and GRK1, and their atomic structures were determined to 2.6 and 1.85 Å spacings, respectively. GSK180736A, developed as a Rho-associated, coiled-coil-containing protein kinase inhibitor, binds to GRK2 in a manner analogous to that of paroxetine, whereas GSK2163632A, developed as an insulin-like growth factor 1 receptor inhibitor, occupies a novel region of the GRK active site cleft that could likely be exploited to achieve more selectivity. However, neither compound inhibits GRKs more potently than their initial targets. This data provides the foundation for future efforts to rationally design even more potent and selective GRK inhibitors.

  6. N-(1'-naphthyl)-3,4,5-trimethoxybenzohydrazide as microtubule destabilizer: Synthesis, cytotoxicity, inhibition of cell migration and in vivo activity against acute lymphoblastic leukemia.

    Science.gov (United States)

    Salum, Lívia B; Mascarello, Alessandra; Canevarolo, Rafael R; Altei, Wanessa F; Laranjeira, Angelo B A; Neuenfeldt, Patrícia D; Stumpf, Taisa R; Chiaradia-Delatorre, Louise D; Vollmer, Laura L; Daghestani, Hikmat N; de Souza Melo, Carolina P; Silveira, André B; Leal, Paulo C; Frederico, Marisa J S; do Nascimento, Leandro F; Santos, Adair R S; Andricopulo, Adriano D; Day, Billy W; Yunes, Rosendo A; Vogt, Andreas; Yunes, José A; Nunes, Ricardo J

    2015-01-01

    Tubulin-interacting agents, like vinca alkaloid and taxanes, play a fundamental role in cancer chemotherapy, making cellular microtubules (MT), one of the few validated anticancer targets. Cancer resistance to classical MT inhibitors has motivated the development of novel molecules with increased efficacy and lower toxicity. Aiming at designing structurally-simple inhibitors of MT assembly, we synthesized a series of thirty-one 3,4,5-trimethoxy-hydrazones and twenty-five derivatives or analogs. Docking simulations suggested that a representative N-acylhydrazone could adopt an appropriate stereochemistry inside the colchicine-binding domain of tubulin. Several of these compounds showed anti-leukemia effects in the nanomolar concentration range. Interference with MT polymerization was validated by the compounds' ability to inhibit MT assembly at the biochemical and cellular level. Selective toxicity investigations done with the most potent compound, a 3,4,5-trimethoxy-hydrazone with a 1-naphthyl group, showed remarkably selective toxicity against leukemia cells in comparison with stimulated normal lymphocytes, and no acute toxicity in vivo. Finally, this molecule was as active as vincristine in a murine model of human acute lymphoblastic leukemia at a weekly dose of 1 mg/kg.

  7. Results of Aluminosilicate Inhibitor Testing

    Energy Technology Data Exchange (ETDEWEB)

    Wilmarth, W.R.

    2001-06-27

    The aluminosilicate scale in the 2H Evaporator has precluded operation since late 1999. The chemistry of scale formation is known but the mechanism(s) for deposition are not well understood. Tests have been conducted to determine if chemical agents could prevent aluminosilicate formation under conditions similar to Tank 43H. Additionally, particle growth inhibition is also tested.

  8. Two additive mechanisms impair the differentiation of 'substrate-selective' p38 inhibitors from classical p38 inhibitors in vitro

    Directory of Open Access Journals (Sweden)

    Seidl Kelly M

    2010-03-01

    Full Text Available Abstract Background The success of anti-TNF biologics for the treatment of rheumatoid arthritis has highlighted the importance of understanding the intracellular pathways that regulate TNF production in the quest for an orally-available small molecule inhibitor. p38 is known to strongly regulate TNF production via MK2. The failure of several p38 inhibitors in the clinic suggests the importance of other downstream pathways in normal cell function. Recent work has described a 'substrate-selective' p38 inhibitor that is able to preferentially block the activity of p38 against one substrate (MK2 versus another (ATF2. Using a combined experimental and computational approach, we have examined this mechanism in greater detail for two p38 substrates, MK2 and ATF2. Results We found that in a dual (MK2 and ATF2 substrate assay, MK2-p38 interaction reduced the activity of p38 against ATF2. We further constructed a detailed kinetic mechanistic model of p38 phosphorylation in the presence of multiple substrates and successfully predicted the performance of classical and so-called 'substrate-selective' p38 inhibitors in the dual substrate assay. Importantly, it was found that excess MK2 results in a stoichiometric effect in which the formation of p38-MK2-inhibitor complex prevents the phosphorylation of ATF2, despite the preference of the compound for the p38-MK2 complex over the p38-ATF2 complex. MK2 and p38 protein expression levels were quantified in U937, Thp-1 and PBMCs and found that [MK2] > [p38]. Conclusion Our integrated mechanistic modeling and experimental validation provides an example of how systems biology approaches can be applied to drug discovery and provide a basis for decision-making with limited chemical matter. We find that, given our current understanding, it is unlikely that 'substrate-selective' inhibitors of p38 will work as originally intended when placed in the context of more complex cellular environments, largely due to a

  9. Glycine Transporters and Their Inhibitors

    Science.gov (United States)

    Gilfillan, Robert; Kerr, Jennifer; Walker, Glenn; Wishart, Grant

    Glycine plays a ubiquitous role in many biological processes. In the central nervous system it serves as an important neurotransmitter acting as an agonist at strychnine-sensitive glycine receptors and as an essential co-agonist with glutamate at the NMDA receptor complex. Control of glycine concentrations in the vicinity of these receptors is mediated by the specific glycine transporters, GlyT1 and GlyT2. Inhibition of these transporters has been postulated to be of potential benefit in several therapeutic indications including schizophrenia and pain. In this review we discuss our current knowledge of glycine transporters and focus on recent advances in the medicinal chemistry of GlyT1 and GlyT2 inhibitors.

  10. TYROSINE KINASE INHIBITORS AND PREGNANCY

    Directory of Open Access Journals (Sweden)

    Elisabetta Abruzzese

    2014-04-01

    Full Text Available The management of patients with chronic myeloid leukemia (CML during pregnancy has became recently a matter of continuous debate.  The introduction of the Tyrosine Kinase Inhibitors (TKIs in clinical practice has dramatically changed the prognosis of CML patients.  Patients diagnosed in chronic phase can reasonably expect many years of excellent disease control and good quality of life, as well as a normal life expectancy.  This fact has come the necessity to address issues relating to fertility and pregnancy. Physicians are not infrequently being asked for advice regarding the need for, and or the appropriateness of, stopping treatment in order to conceive. In this report we will review the data published in terms of fertility, conception, pregnancy, pregnancy outcome and illness control for all the approved TKIs, as well as suggest how to manage a planned and/or unplanned pregnancy.

  11. Aromatase inhibitors in gynecologic cancers.

    Science.gov (United States)

    Krasner, Carolyn

    2007-01-01

    The female genital tract is hormonally responsive, and consequently some tumors, which arise within in it, may be treated at least in part, with hormonal manipulation. The range of responses in clinical trials and case reports will be reviewed. Many of these diseases are too rare for clinical trial testing, and in some cases evidence is anecdotal at best. Recurrences of ovarian cancer have been treated with tamoxifen and megesterol acetate with variable response rates from 0 to 56%. The favorable toxicity profile of aromatase inhibitors led to trials of these agents for the treatment of relapsed epithelial ovarian cancer. These agents have proved tolerable with minor response rates but a significant disease stabilization rate, which may be prolonged in a minority of cases. It is unclear if these responses may be predicted by estrogen receptor expression or aromatase expression. Anastrazole has also been tried in combination with an EGFR receptor-inhibitor, again showing minor responses but possibly an increase in TTT in some patients. Granulosa cell tumors of the ovary are rare, hormonally sensitive tumors, with reported responses to a variety of hormonal manipulations, including aromatase inhibition. In addition, combined endocrine blockade, including aromatase inhibition, has been tried with reports of success. Endometrial cancers, particularly type I lesions, are often treated with hormonal manipulation, most commonly with progestins, but also with antiestrogens such as tamoxifen. A trial of aromatase inhibition in the treatment of recurrent endometrial cancer showed minimal responses. Endometrial stromal sarcoma, an uncommon uterine malignancy, has shown response to hormonal treatments, with multiple case reports of efficacy of aromatase inhibition. Despite the rarity of some of these tumor types, rare tumor study groups, such as within the Gynecologic Oncology Group, should make an effort to prospectively define the utility of these treatments.

  12. Structure and inhibitor specificity of the PCTAIRE-family kinase CDK16.

    Science.gov (United States)

    Dixon-Clarke, Sarah E; Shehata, Saifeldin N; Krojer, Tobias; Sharpe, Timothy D; von Delft, Frank; Sakamoto, Kei; Bullock, Alex N

    2017-02-20

    CDK16 (also known as PCTAIRE1 or PCTK1) is an atypical member of the cyclin-dependent kinase (CDK) family that has emerged as a key regulator of neurite outgrowth, vesicle trafficking and cancer cell proliferation. CDK16 is activated through binding to cyclin Y via a phosphorylation-dependent 14-3-3 interaction and has a unique consensus substrate phosphorylation motif compared with conventional CDKs. To elucidate the structure and inhibitor-binding properties of this atypical CDK, we screened the CDK16 kinase domain against different inhibitor libraries and determined the co-structures of identified hits. We discovered that the ATP-binding pocket of CDK16 can accommodate both type I and type II kinase inhibitors. The most potent CDK16 inhibitors revealed by cell-free and cell-based assays were the multitargeted cancer drugs dabrafenib and rebastinib. An inactive DFG-out binding conformation was confirmed by the first crystal structures of CDK16 in separate complexes with the inhibitors indirubin E804 and rebastinib, respectively. The structures revealed considerable conformational plasticity, suggesting that the isolated CDK16 kinase domain was relatively unstable in the absence of a cyclin partner. The unusual structural features and chemical scaffolds identified here hold promise for the development of more selective CDK16 inhibitors and provide opportunity to better characterise the role of CDK16 and its related CDK family members in various physiological and pathological contexts.

  13. Structure and inhibitor specificity of the PCTAIRE-family kinase CDK16

    Science.gov (United States)

    Dixon-Clarke, Sarah E.; Shehata, Saifeldin N.; Krojer, Tobias; Sharpe, Timothy D.; vonDelft, Frank; Sakamoto, Kei

    2017-01-01

    CDK16 (also known as PCTAIRE1 or PCTK1) is an atypical member of the cyclin-dependent kinase (CDK) family that has emerged as a key regulator of neurite outgrowth, vesicle trafficking and cancer cell proliferation. CDK16 is activated through binding to cyclin Y via a phosphorylation-dependent 14-3-3 interaction and has a unique consensus substrate phosphorylation motif compared with conventional CDKs. To elucidate the structure and inhibitor-binding properties of this atypical CDK, we screened the CDK16 kinase domain against different inhibitor libraries and determined the co-structures of identified hits. We discovered that the ATP-binding pocket of CDK16 can accommodate both type I and type II kinase inhibitors. The most potent CDK16 inhibitors revealed by cell-free and cell-based assays were the multitargeted cancer drugs dabrafenib and rebastinib. An inactive DFG-out binding conformation was confirmed by the first crystal structures of CDK16 in separate complexes with the inhibitors indirubin E804 and rebastinib, respectively. The structures revealed considerable conformational plasticity, suggesting that the isolated CDK16 kinase domain was relatively unstable in the absence of a cyclin partner. The unusual structural features and chemical scaffolds identified here hold promise for the development of more selective CDK16 inhibitors and provide opportunity to better characterise the role of CDK16 and its related CDK family members in various physiological and pathological contexts. PMID:28057719

  14. Histone deacetylase inhibitors improve the replication of oncolytic herpes simplex virus in breast cancer cells.

    Directory of Open Access Journals (Sweden)

    James J Cody

    Full Text Available New therapies are needed for metastatic breast cancer patients. Oncolytic herpes simplex virus (oHSV is an exciting therapy being developed for use against aggressive tumors and established metastases. Although oHSV have been demonstrated safe in clinical trials, a lack of sufficient potency has slowed the clinical application of this approach. We utilized histone deacetylase (HDAC inhibitors, which have been noted to impair the innate antiviral response and improve gene transcription from viral vectors, to enhance the replication of oHSV in breast cancer cells. A panel of chemically diverse HDAC inhibitors were tested at three different doses (LD50 for their ability to modulate the replication of oHSV in breast cancer cells. Several of the tested HDAC inhibitors enhanced oHSV replication at low multiplicity of infection (MOI following pre-treatment of the metastatic breast cancer cell line MDA-MB-231 and the oHSV-resistant cell line 4T1, but not in the normal breast epithelial cell line MCF10A. Inhibitors of class I HDACs, including pan-selective compounds, were more effective for increasing oHSV replication compared to inhibitors that selectively target class II HDACs. These studies demonstrate that select HDAC inhibitors increase oHSV replication in breast cancer cells and provides support for pre-clinical evaluation of this combination strategy.

  15. A Rational Approach for the Identification of Non-Hydroxamate HDAC6-Selective Inhibitors

    Science.gov (United States)

    Goracci, Laura; Deschamps, Nathalie; Randazzo, Giuseppe Marco; Petit, Charlotte; Dos Santos Passos, Carolina; Carrupt, Pierre-Alain; Simões-Pires, Claudia; Nurisso, Alessandra

    2016-07-01

    The human histone deacetylase isoform 6 (HDAC6) has been demonstrated to play a major role in cell motility and aggresome formation, being interesting for the treatment of multiple tumour types and neurodegenerative conditions. Currently, most HDAC inhibitors in preclinical or clinical evaluations are non-selective inhibitors, characterised by a hydroxamate zinc-binding group (ZBG) showing off-target effects and mutagenicity. The identification of selective HDAC6 inhibitors with novel chemical properties has not been successful yet, also because of the absence of crystallographic information that makes the rational design of HDAC6 selective inhibitors difficult. Using HDAC inhibitory data retrieved from the ChEMBL database and ligand-based computational strategies, we identified 8 original new non-hydroxamate HDAC6 inhibitors from the SPECS database, with activity in the low μM range. The most potent and selective compound, bearing a hydrazide ZBG, was shown to increase tubulin acetylation in human cells. No effects on histone H4 acetylation were observed. To the best of our knowledge, this is the first report of an HDAC6 selective inhibitor bearing a hydrazide ZBG. Its capability to passively cross the blood-brain barrier (BBB), as observed through PAMPA assays, and its low cytotoxicity in vitro, suggested its potential for drug development.

  16. Pharmacophore Modeling, Virtual Screening, and Molecular Docking Studies for Discovery of Novel Akt2 Inhibitors

    Directory of Open Access Journals (Sweden)

    Jia Fei, Lu Zhou, Tao Liu, Xiang-Yang Tang

    2013-01-01

    Full Text Available Akt2 is considered as a potential target for cancer therapy. In order to find novel Akt2 inhibitors which have different scaffolds, structure-based pharmacophore model and 3D-QSAR pharmacophore model were built and validated by different methods. Then, they were used for chemical databases virtual screening. The selected compounds were further analyzed and refined using drug-like filters and ADMET analysis. Finally, seven hits with different scaffolds were picked out for docking studies. These seven hits were predicted to have high inhibitory activity and good ADMET properties, they may act as novel leads for Akt2 inhibitors designing.

  17. Polyethelene Glycol-Anthranilic Acid Composite as Corrosion Inhibitor for Mild Steel in Acid Medium

    Directory of Open Access Journals (Sweden)

    N. Banumathi

    2010-01-01

    Full Text Available The polymer PGA composite was prepared by chemical oxidative method of polyethylene glycol, anthranilic acid with ammonium persulphate in oxalic acid medium. The resulted polymer was characterized by FTIR spectroscopy. The performance of the polymer polyglycol anthranilic acid composite (PGA as corrosion inhibitor for mild steel in 1 M HCl has been studied by weight loss, potentiodynamic and impedance spectroscopy methods. The maximum IE was found to be 97%. Experimental results were fitted to Langmuir adsorption isotherm. Electrochemical studies confirmed the inhibitive nature of the PGA composite and also the mixed nature of the inhibitor. The polymer is found to be highly efficient non-toxic and environmentally safe.

  18. Study of Plant Cordia Dichotoma as Green Corrosion Inhibitor for Mild Steel in Different Acid Media

    Directory of Open Access Journals (Sweden)

    R. Khandelwal

    2011-01-01

    Full Text Available The corrosion inhibition of mild steel using extracts of Cordia dichotoma in different acid media was investigated by mass loss and thermometric methods. The experiments were carried out at 299±0.2 K in presence of different concentrations of dry fruit, leaves and stem extracts of Cordia dichotoma. The results reveal that the alcoholic extracts of Cordia dichotoma is a better corrosion inhibitor than that of toxic chemicals. The fruit extract is more potent than leaves and stem extracts to inhibit the corrosion rate. The study seeks to investigate the possibility of using extracts of Cordia dichotoma as a green corrosion inhibitor for mild steel.

  19. A computational study on novel carbon-based lithium materials for hydrogen storage and the role of carbon in destabilizing complex metal hydrides

    Science.gov (United States)

    Ghouri, Mohammed Minhaj

    materials with varying amounts of hydrogen. A detailed analysis of the heats of reactions of these materials using different reaction schemes is performed and based on the promising thermodynamic and gravimetric storage density, LiC4Be2H5 is divulged as a promising novel carbon based lithium material. In the later part, this dissertation performs a detailed study on the effect of carbon when it is used as a dopant in four different well known complex hydrides, lithium beryllium hydride (Li2BeH4), lithium borohydride (LiBH4), lithium aluminum hydride (LiAlH 4) and sodium borohydride (NaBH4). Initially, the unit cells of the crystal structure are fully resolved using the plane-wave pseudopotential implementation of DFT. The supercells of each of these are then constructed and optimized. Varying amounts of carbon is introduced as impurity in these crystals in different sites such as the top, subsurface and the bulk of the crystal lattice. Using the electronic structure calculations, it is established that (i) C-Be-H, C-B-H or C-Al-H compounds are formed respectively in the cases of Li2BeH4, LiBH4 and LiAlH4 when carbon is doped in them; (ii) and carbon dopant causes a decrease in the bond strengths of Be-H, B-H and Al-H in respective cases. This reduction in the bond strengths combined with the fact that there is a decrease in the ionic interaction between the cation and the anionic hydride units of these complex hydrides causes a destabilization effect.

  20. Advances of Inhibitors in Drilling Fluid

    Institute of Scientific and Technical Information of China (English)

    杨仕伟; 周丹

    2012-01-01

    The development history of the inhibitors of drilling fluid reviewed in this paper. The advances of inhibitors commonly used at home and abroad were included. That the inhibitive ability was good enough whose inhibiting mechanisms and effects were introduced in the past 10 years.

  1. [Interaction between clopidogrel and proton pump inhibitors

    NARCIS (Netherlands)

    Harmsze, A.M.; Boer, A. de; Boot, H.; Deneer, V.H.; Heringa, M.; Mol, P.G.; Schalekamp, T.; Verduijn, M.M.; Verheugt, F.W.A.; Comte, M. le

    2011-01-01

    The drug interaction between proton pump inhibitors and clopidogrel has been the subject of much study in recent years. Contradictory results regarding the effect of proton pump inhibitors on platelet reactivity and on clinical outcome in clopidogrel-treated patients have been reported in literature

  2. A cyclic peptidic serine protease inhibitor

    DEFF Research Database (Denmark)

    Zhao, Baoyu; Xu, Peng; Jiang, Longguang;

    2014-01-01

    Peptides are attracting increasing interest as protease inhibitors. Here, we demonstrate a new inhibitory mechanism and a new type of exosite interactions for a phage-displayed peptide library-derived competitive inhibitor, mupain-1 (CPAYSRYLDC), of the serine protease murine urokinase...

  3. Chemical genetics to examine cellulose biosynthesis

    Directory of Open Access Journals (Sweden)

    Seth eDebolt

    2013-01-01

    Full Text Available Long-term efforts to decode plant cellulose biosynthesis via molecular genetics and biochemical strategies are being enhanced by the ever-expanding scale of omics technologies. An alternative approach to consider are the prospects for inducing change in plant metabolism using exogenously supplied chemical ligands. Cellulose biosynthesis inhibitors (CBI have been identified among known herbicides, during diverse combinatorial chemical libraries screens, and natural chemical screens from microbial agents. In this review, we summarize the current knowledge of the inhibitory effects of CBIs and further group them by how they influence fluorescently tagged cellulose synthase A (CESA proteins. Additional attention is paid to the continuing development of the CBI toolbox to explore the cell biology and genetic mechanisms underpinning effector molecule activity.

  4. Protein Structure Determination Using Chemical Shifts

    DEFF Research Database (Denmark)

    Christensen, Anders Steen

    In this thesis, a protein structure determination using chemical shifts is presented. The method is implemented in the open source PHAISTOS protein simulation framework. The method combines sampling from a generative model with a coarse-grained force field and an energy function that includes...... chemical shifts. The method is benchmarked on folding simulations of five small proteins. In four cases the resulting structures are in excellent agreement with experimental data, the fifth case fail likely due to inaccuracies in the energy function. For the Chymotrypsin Inhibitor protein, a structure...... is determined using only chemical shifts recorded and assigned through automated processes. The CARMSD to the experimental X-ray for this structure is 1.1. Å. Additionally, the method is combined with very sparse NOE-restraints and evolutionary distance restraints and tested on several protein structures >100...

  5. Histone deacetylase inhibitors (HDACIs: multitargeted anticancer agents

    Directory of Open Access Journals (Sweden)

    Ververis K

    2013-02-01

    Full Text Available Katherine Ververis,1 Alison Hiong,1 Tom C Karagiannis,1,* Paul V Licciardi2,*1Epigenomic Medicine, Alfred Medical Research and Education Precinct, 2Allergy and Immune Disorders, Murdoch Childrens Research Institute, Melbourne, VIC, Australia*These authors contributed equally to this workAbstract: Histone deacetylase (HDAC inhibitors are an emerging class of therapeutics with potential as anticancer drugs. The rationale for developing HDAC inhibitors (and other chromatin-modifying agents as anticancer therapies arose from the understanding that in addition to genetic mutations, epigenetic changes such as dysregulation of HDAC enzymes can alter phenotype and gene expression, disturb homeostasis, and contribute to neoplastic growth. The family of HDAC inhibitors is large and diverse. It includes a range of naturally occurring and synthetic compounds that differ in terms of structure, function, and specificity. HDAC inhibitors have multiple cell type-specific effects in vitro and in vivo, such as growth arrest, cell differentiation, and apoptosis in malignant cells. HDAC inhibitors have the potential to be used as monotherapies or in combination with other anticancer therapies. Currently, there are two HDAC inhibitors that have received approval from the US FDA for the treatment of cutaneous T-cell lymphoma: vorinostat (suberoylanilide hydroxamic acid, Zolinza and depsipeptide (romidepsin, Istodax. More recently, depsipeptide has also gained FDA approval for the treatment of peripheral T-cell lymphoma. Many more clinical trials assessing the effects of various HDAC inhibitors on hematological and solid malignancies are currently being conducted. Despite the proven anticancer effects of particular HDAC inhibitors against certain cancers, many aspects of HDAC enzymes and HDAC inhibitors are still not fully understood. Increasing our understanding of the effects of HDAC inhibitors, their targets and mechanisms of action will be critical for the

  6. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  7. Molecular modeling study for inhibition mechanism of human chymase and its application in inhibitor design.

    Directory of Open Access Journals (Sweden)

    Mahreen Arooj

    Full Text Available Human chymase catalyzes the hydrolysis of peptide bonds. Three chymase inhibitors with very similar chemical structures but highly different inhibitory profiles towards the hydrolase function of chymase were selected with the aim of elucidating the origin of disparities in their biological activities. As a substrate (angiotensin-I bound crystal structure is not available, molecular docking was performed to dock the substrate into the active site. Molecular dynamics simulations of chymase complexes with inhibitors and substrate were performed to calculate the binding orientation of inhibitors and substrate as well as to characterize conformational changes in the active site. The results elucidate details of the 3D chymase structure as well as the importance of K40 in hydrolase function. Binding mode analysis showed that substitution of a heavier Cl atom at the phenyl ring of most active inhibitor produced a great deal of variation in its orientation causing the phosphinate group to interact strongly with residue K40. Dynamics simulations revealed the conformational variation in region of V36-F41 upon substrate and inhibitor binding induced a shift in the location of K40 thus changing its interactions with them. Chymase complexes with the most active compound and substrate were used for development of a hybrid pharmacophore model which was applied in databases screening. Finally, hits which bound well at the active site, exhibited key interactions and favorable electronic properties were identified as possible inhibitors for chymase. This study not only elucidates inhibitory mechanism of chymase inhibitors but also provides key structural insights which will aid in the rational design of novel potent inhibitors of the enzyme. In general, the strategy applied in the current study could be a promising computational approach and may be generally applicable to drug design for other enzymes.

  8. A competitive nucleotide binding inhibitor: in vitro characterization of Rab7 GTPase inhibition.

    Science.gov (United States)

    Agola, Jacob O; Hong, Lin; Surviladze, Zurab; Ursu, Oleg; Waller, Anna; Strouse, J Jacob; Simpson, Denise S; Schroeder, Chad E; Oprea, Tudor I; Golden, Jennifer E; Aubé, Jeffrey; Buranda, Tione; Sklar, Larry A; Wandinger-Ness, Angela

    2012-06-15

    Mapping the functionality of GTPases through small molecule inhibitors represents an underexplored area in large part due to the lack of suitable compounds. Here we report on the small chemical molecule 2-(benzoylcarbamothioylamino)-5,5-dimethyl-4,7-dihydrothieno[2,3-c]pyran-3-carboxylic acid (PubChem CID 1067700) as an inhibitor of nucleotide binding by Ras-related GTPases. The mechanism of action of this pan-GTPase inhibitor was characterized in the context of the Rab7 GTPase as there are no known inhibitors of Rab GTPases. Bead-based flow cytometry established that CID 1067700 has significant inhibitory potency on Rab7 nucleotide binding with nanomolar inhibitor (K(i)) values and an inhibitory response of ≥97% for BODIPY-GTP and BODIPY-GDP binding. Other tested GTPases exhibited significantly lower responses. The compound behaves as a competitive inhibitor of Rab7 nucleotide binding based on both equilibrium binding and dissociation assays. Molecular docking analyses are compatible with CID 1067700 fitting into the nucleotide binding pocket of the GTP-conformer of Rab7. On the GDP-conformer, the molecule has greater solvent exposure and significantly less protein interaction relative to GDP, offering a molecular rationale for the experimental results. Structural features pertinent to CID 1067700 inhibitory activity have been identified through initial structure-activity analyses and identified a molecular scaffold that may serve in the generation of more selective probes for Rab7 and other GTPases. Taken together, our study has identified the first competitive GTPase inhibitor and demonstrated the potential utility of the compound for dissecting the enzymology of the Rab7 GTPase, as well as serving as a model for other small molecular weight GTPase inhibitors.

  9. Chemical Security Analysis Center

    Data.gov (United States)

    Federal Laboratory Consortium — In 2006, by Presidential Directive, DHS established the Chemical Security Analysis Center (CSAC) to identify and assess chemical threats and vulnerabilities in the...

  10. Theoretical studies on the interaction between the nitrile-based inhibitors and the catalytic triad of Cathepsin K.

    Science.gov (United States)

    Pitchumani Violet Mary, C; Shankar, R; Vijayakumar, S

    2017-02-20

    Computational studies on the interaction of novel inhibitor compounds with the Cathepsin K protease have been performed to study the inhibition properties of the inhibitor compounds. The quantum chemical calculations have been performed to analyze the molecular geometries, structural stability, reactivity, nature of interaction, and the charge transfer properties using B3LYP level of theory by implementing 6-311g(d,p) basis set. The calculated C-S and N-H…N bond lengths of the inhibitor-triad complexes are found to agree well with the previous literature results. The chemical reactivity of the inhibitors and catalytic triad are analyzed through frontier molecular orbital analysis and found that the inhibitors are subjected to nucleophilic attack by the catalytic triad. The nature of inhibition of the inhibitor compounds is examined using the quantum theory of Atoms in Molecules analysis and found to be partially covalent. The NBO stabilization energy for the Cys - inhibitor are found to be most stable than the other interactions. The molecular dynamic simulations were performed to study the influence of dynamic of the active site on the QM results. The many body decomposition interaction energy calculated for the final results of MD simulation reveals that the dynamic of the active site induces significant changes in the interaction energy and occupancy of H-bonds plays a major role in the stabilizing the active site inhibitor interactions. The present study reveals that the inhibitor compounds can inhibit the proteolytic activity of the proteases on binding with the catalytic active site.

  11. Differential Chemical Protection of Mammalian Cells from the Exotoxins of ’Corynebacterium diphtheriae’ and ’Pseudomonas aeruginosa’,

    Science.gov (United States)

    Many drugs or chemicals had markedly different effects on the cytotoxicity induced by Pseudomonas aeruginosa exotoxin A (PE) or Corynebacterium ... diphtheriae exotoxin (DE). The glycolytic inhibitor NaF protected cells from DE but potentiated the cytotoxicity of PE. Another energy inhibitor, salicylic

  12. Effect of inorganic inhibitors on the corrosion behavior of 1018 carbon steel in the LiBr + ethylene glycol + H{sub 2}O mixture

    Energy Technology Data Exchange (ETDEWEB)

    Samiento-Bustos, E. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos. Av. Universidad 1001, Col. Chamilpa, CP 62210, Cuernavaca, Morelos (Mexico); Rodriguez, J.G. Gonzalez [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos. Av. Universidad 1001, Col. Chamilpa, CP 62210, Cuernavaca, Morelos (Mexico)], E-mail: ggonzalez@uaem.mx; Uruchurtu, J. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos. Av. Universidad 1001, Col. Chamilpa, CP 62210, Cuernavaca, Morelos (Mexico); Dominguez-Patino, G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos. Av. Universidad 1001, Col. Chamilpa, CP 62210, Cuernavaca, Morelos (Mexico); U.A.E.M. Facultad de Ciencias Quimicas e Ingenieria, Av. Universidad 1001, 62209, Cuernavaca, Morelos (Mexico); Salinas-Bravo, V.M. [Instituto de Investigaciones Electricas, Gerencia de Materiales y Proceso Quimicos, Av. Reforma 113, Col. Palmira, CP 62490, Cuernavaca, Morelos (Mexico)

    2008-08-15

    The effect of inorganic inhibitors on the corrosion behavior of 1018 carbon steel in the mixture LiBr (55%) + ethylene glycol + H{sub 2}O at room temperature has been evaluated. Used inhibitors included LiNO{sub 3} (Lithium Nitrate), Li{sub 2}MoO{sub 4} (Lithium Molybdate) and Li{sub 2}CrO{sub 4} (Lithium Chromate) at concentrations of 5, 20 and 50 ppm. Electrochemical techniques included potentiodynamic polarization curves, electrochemical noise resistance (EN) and electrochemical impedance spectroscopy (EIS) measurements. Additionally, adsorption isotherms were calculated. The results obtained showed that both, the corrosion rate and the passive current density decreased with inhibitors, and, in general terms, inhibitors efficiency increased with inhibitor concentration, except in the case of Li{sub 2}CrO{sub 4,} where the highest efficiency was obtained with 20 ppm of inhibitor. Pitting potential with 5 ppm of inhibitor