997 resultados para 120-750
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UANL
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The pathogenesis of hepatic encephalopathy is multifactorial, involving gut-derived toxins such as ammonia, which has been demonstrated to induce oxidative stress. Therefore, a primary hepatic encephalopathy treatment target is reducing ammonia production in the gastrointestinal tract. AST-120, an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600 m(2) /g, acts as a sink for neurotoxins and hepatotoxins present in the gut. We evaluated the capacity of AST-120 to adsorb ammonia in vitro and to lower blood ammonia, oxidative stress and brain edema in cirrhotic rats. Cirrhosis was induced in rats by bile duct ligation for 6 weeks. AST-120 was administered by gavage preventively for 6 weeks (0.1, 1, and 4 g/kg/day). In addition, AST-120 was evaluated as a short-term treatment for 2 weeks and 3 days (1 g/kg/day) and as a sink to adsorb intravenously infused ammonium acetate. In vitro, AST-120 efficiently adsorbed ammonia. Ammonia levels significantly decreased in a dose-dependent manner for all AST-120-treated bile duct-ligated rats (nontreated: 177.3 ± 30.8 μM; AST-120, 0.1 g/kg/day: 121.9 ± 13.8 μM; AST-120, 1 g/kg/day: 80.9 ± 30.0 μM; AST-120, 4 g/kg/day: 48.8 ± 19.6 μM) and significantly correlated with doses of AST-120 (r = -0.6603). Brain water content and locomotor activity normalized after AST-120 treatments, whereas arterial reactive oxygen species levels remained unchanged. Furthermore, AST-120 significantly attenuated a rise in arterial ammonia after ammonium acetate administration (intravenously). Conclusion:AST-120 treatment decreased arterial ammonia levels, normalized brain water content and locomotor activity but did not demonstrate an effect on systemic oxidative stress. Also, AST-120 acts as an ammonia sink, efficiently removing blood-derived ammonia. Additional studies are warranted to evaluate the effects of AST-120 on hepatic encephalopathy in patients with advanced liver disease. (HEPATOLOGY 2011;).
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Seed moisture content is significant in the handling and processing of seeds. This work therefore determined the physical properties of Locust bean seeds as functions of seed moisture content in the moisture range of 5.9 – 28.2% dry basis. Mohsenin, Stepanoff and ASAE standard methods were used in determining the properties. Increases in seed dimensions vitz length = 10.2±1.0 – 11.3±0.9 mm; width = 8.5±0.8 – 9.1±0.6 mm; surface area = 191.2±24.6 – 208.3±26.3 mm2 ; geometric mean diameter = 7.78±0.49 – 8.12±0.03 and arithmetic mean diameter = 8.06±0.56 – 8.34±0.49 mm were recorded. Seed thickness = 5.49±0.43 – 5.26±0.62 mm; sphericity = 0.75±0.04 – 0.71±0.03; true density = 1251.96±55.5 - 1222±62.16 kgm-3 and porosity = 48.4±2.14 – 41.9±3.78 decreased. Static coefficient of friction increased on plywood (0.5±0.02 – 0.6±0.01), glass (0.4±0.05 – 0.5±0.01) and decreased on aluminium (0.5±0.02 – 0.5±0.04). A data of the physical properties of Locust bean; Parkia biglobosa was developed. This is useful for the design and development of equipment necessary for its handling and processing.
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The human immunodeficiency virus (HIV) envelope (Env) glycoprotein (gp) 120 is a highly disulfide-bonded molecule that attaches HIV to the lymphocyte surface receptors CD4 and CXCR4. Conformation changes within gp120 result from binding and trigger HIV/cell fusion. Inhibition of lymphocyte surface-associated protein-disulfide isomerase (PDI) blocks HIV/cell fusion, suggesting that redox changes within Env are required. Using a sensitive assay based on a thiol reagent, we show that (i) the thiol content of gp120, either secreted by mammalian cells or bound to a lymphocyte surface enabling CD4 but not CXCR4 binding, was 0.5-1 pmol SH/pmol gp120 (SH/gp120), whereas that of gp120 after its interaction with a surface enabling both CD4 and CXCR4 binding was raised to 4 SH/gp120; (ii) PDI inhibitors prevented this change; and (iii) gp120 displaying 2 SH/gp120 exhibited CD4 but not CXCR4 binding capacity. In addition, PDI inhibition did not impair gp120 binding to receptors. We conclude that on average two of the nine disulfides of gp120 are reduced during interaction with the lymphocyte surface after CXCR4 binding prior to fusion and that cell surface PDI catalyzes this process. Disulfide bond restructuring within Env may constitute the molecular basis of the post-receptor binding conformational changes that induce fusion competence.
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L'organisation des manuscrits arthuriens du cycle du Graal de Jacques d'Armagnac (BNF fr. 117-120 qu'il a hérité de son arrière-grand-père le duc Jean de Berry et dont il a fait retoucher les peintures et BNF fr. 113-116 qu'il a fait exécuter entre 1470 et 1475), leur agencement, leur illustration et leurs subdivisions sont un indice précieux de la conception et de la réception de ces compilations. Ils soulignent l'effort de constitution d'un ensemble romanesque cohérent centré sur la figure de Lancelot.
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A new global synthesis and biomization of long (>40 kyr) pollen-data records is presented, and used with simulations from the HadCM3 and FAMOUS climate models to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial–interglacial cycle. Global modelled (BIOME4) biome distributions over time generally agree well with those inferred from pollen data. The two climate models show good agreement in global net primary productivity (NPP). NPP is strongly influenced by atmospheric carbon dioxide (CO2) concentrations through CO2 fertilization. The combined effects of modelled changes in vegetation and (via a simple model) soil carbon result in a global terrestrial carbon storage at the Last Glacial Maximum that is 210–470 Pg C less than in pre-industrial time. Without the contribution from exposed glacial continental shelves the reduction would be larger, 330–960 Pg C. Other intervals of low terrestrial carbon storage include stadial intervals at 108 and 85 ka BP, and between 60 and 65 ka BP during Marine Isotope Stage 4. Terrestrial carbon storage, determined by the balance of global NPP and decomposition, influences the stable carbon isotope composition (δ13C) of seawater because terrestrial organic carbon is depleted in 13C. Using a simple carbon-isotope mass balance equation we find agreement in trends between modelled ocean δ13C based on modelled land carbon storage, and palaeo-archives of ocean δ13C, confirming that terrestrial carbon storage variations may be important drivers of ocean δ13C changes.
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A new global synthesis and biomization of long (> 40 kyr) pollen-data records is presented and used with sim- ulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial–interglacial cycle. Simulated biome distribu- tions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those in- ferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large- scale increases during the Last Glacial Maximum, between ca. 64 and 74 ka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are re- flected in BIOME4 simulations of global net primary pro- ductivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composi- tion of seawater as terrestrial carbon is depleted in 13C.
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The hysteretic behavior of mechanically alloyed nanocomposites FeCo + MnO was studied at high temperatures. These composites present an unusual high and thermally stable coercivity, compared to FeCo milled at equal conditions. Coercivity enhancement was observed in hysteresis loops obtained between room temperature and 750 K. It is attributed to the isolation of the FeCo ferromagnetic particles by the paramagnetic MnO (T(N) = 120 K). The M(rev)(M(irr))(H) curves are clearly linear for the composite, indicating that coherent rotation is the reversal mechanism in these materials. (C) 2008 Elsevier B.V. All rights reserved.
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The studied sector of the central Ribeira Fold Belt (SE Brazil) comprises metatexites, diatexites, charnockites and blastomylonites. This study integrates petrological and thermochronological data in order to constrain the thermotectonic and geodynamic evolution of this Neoproterozoic-Ordovician mobile belt during Western Gondwana amalgamation. New data indicate that after an earlier collision stage at similar to 610 Ma (zircon, U-Pb age), peak metamorphism and lower crust partial melting, coeval with the main regional high grade D(1) thrust deformation, occurred at 572-562 Ma (zircon, U-Pb ages). The overall average cooling rate was low (<5 degrees C/Ma) from 750 to 250 degrees C (at similar to 455 Ma; biotite-WR Rb-Sr age), but disparate cooling paths indicate differential uplift between distinct lithotypes: (a) metatexites and blastomylonites show a overall stable 3-5 degrees C/Ma cooling rate; (b) charnockites and associated rocks remained at T>650 degrees C during sub-horizontal D(2) shearing until similar to 510-470 Ma (garnet-WR Sm-Nd ages) (1-2 degrees C/Ma), being then rapidly exhumed/cooled (8-30 degrees C/Ma) during post-orogenic D(3) deformation with late granite emplacement at similar to 490 Ma (zircon, U-Pb age). Cooling rates based on garnet-biotite Fe-Mg diffusion are broadly consistent with the geochronological cooling rates: (a) metatexites were cooled faster at high temperatures (6 degrees C/Ma) and slowly at low temperatures (0.1 degrees C/Ma), decreasing cooling rates with time; (b) charnockites show low cooling rates (2 degrees C/Ma) near metamorphic peak conditions and high cooling rates (120 degrees C/Ma) at lower temperatures, increasing cooling rates during retrogression. The charnockite thermal evolution and the extensive production of granitoid melts in the area imply that high geothermal gradients were sustained fora long period of time (50-90 Ma). This thermal anomaly most likely reflects upwelling of asthenospheric mantle and magma underplating coupled with long-term generation of high HPE (heat producing elements) granitoids. These factors must have sustained elevated crustal geotherms for similar to 100 Ma, promoting widespread charnockite generation at middle to lower crustal levels. (C) 2010 Elsevier B.V. All rights reserved.
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In this report, we describe the microfabrication and integration of planar electrodes for contactless conductivity detection on polyester-toner (PT) electrophoresis microchips using toner masks. Planar electrodes were fabricated by three simple steps: (i) drawing and laser-printing the electrode geometry on polyester films, (ii) sputtering deposition onto substrates, and (iii) removal of toner layer by a lift-off process. The polyester film with anchored electrodes was integrated to PT electrophoresis microchannels by lamination at 120 degrees C in less than 1 min. The electrodes were designed in an antiparallel configuration with 750 mu m width and 750 gm gap between them. The best results were recorded with a frequency of 400 kHz and 10 V-PP using a sinusoidal wave. The analytical performance of the proposed microchip was evaluated by electrophoretic separation of potassium, sodium and lithium in 150 mu m wide x 6 mu m deep microchannels. Under an electric field of 250 V/cm the analytes were successfully separated in less than 90 s with efficiencies ranging from 7000 to 13 000 plates. The detection limits (S/N = 3) found for K+, Na+, and Li+ were 3.1, 4.3, and 7.2 mu mol/L, respectively. Besides the low-cost and instrumental simplicity, the integrated PT chip eliminates the problem of manual alignment and gluing of the electrodes, permitting more robustness and better reproducibility, therefore, more suitable for mass production of electrophoresis microchips.
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Som componente do jogo “Musikinésia (http://www.loa.sead.ufscar.br/musikinesia.php)” desenvolvido pela equipe do Laboratório de Objetos de Aprendizagem da Universidade Federal de São Carlos (LOA/UFSCar).