990 resultados para 383
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The myotoxic Lys-49 phospholipase bothropstoxin I was crystallized, and X-ray diffraction data were collected to 3.5 Angstrom resolution. Preliminary analysis reveals the presence of four molecules in the asymmetric unit.
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The magnetic order resulting from the indirect exchange in the metallic phase of a (Ga,Mn)As/GaAs double layer structure is studied via Monte Carlo simulation. The polarization of the hole gas is taken into account, establishing a self-consistency between the magnetic order and the electronic structure. The Curie-Weiss temperatures calculated for these low-dimensional systems are in the range of 50-80 K, and the dependence of the transition temperature with the GaAs separation layer is established. (C) 2003 Published by Elsevier B.V.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Transposable elements are major components of plant genomes and they influence their evolution, acting as recombination hot spots, acquiring specific cell functions or becoming part of protein-coding regions. The latter is the subject of the present analysis. This study is a report on the annotation of transposable elements (TEs) in expressed sequences of Coffea arabica, Coffea canephora and Coffea racemosa, showing the occurrence of 383 ESTs and 142 unigenes with TE fragments in these three Coffea species. Based on selected unigenes, it was possible to suggest 26 putative proteins with TE-cassette insertions, demonstrating a likely contribution to protein variability. The genes for two of those proteins, the fertility restorer (FR) and the pyrophosphate-dependent phosphofructokinase (PPi-PFKs) genes, were selected for evaluating the impact of TE-cassettes on host gene evolution of other plant genomes (Arabidopsis thaliana, Oryza sativa and populus trichocarpa). This survey allowed identifying a FR gene in O. sativa harboring multiple insertions of LTR retrotransposons that originated new exons, which however does not necessarily mean a case of molecular domestication. A possible transduction event of a fragment of the PPi-PFK beta-subunit gene mediated by Helitron ATREPX1 in Arabidopsis thaliana was also highlighted.
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The synthesis, spectroscopic characterization, and thermal analysis of the compounds [Pd(X)(2)(mtu)(PPh3)] (X = Cl- (1), SCN- (2); mtu = N-methylthiourea; PPh3 = triphenylphosphine) and [Pd(X)(2)(phtu)(PPh3)] (X = Cl- (3), SCN- (4); phtu = N-phenylthiourea) are described. The thermal decomposition of the compounds occurs in two, three, or four stages and the final decomposition products were identified as Pd-0 by X-ray powder diffraction. The thermal stability order of the complexes is 4 > 3 > 2 > 1.
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Bi4Ti4O15 [BBT], a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of BaTiO3 [BT] and Bi4Ti3O12 [BIT] obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. BBT ceramics were sintered at 1100C for 4 h without pre-calcination step within heating rate 10C/min. The formation of phase and crystal structure of BT, BIT and BBT were approved using X-ray analysis. The morphology of obtained powders and microstructure were exhamined using scanning electron microscopy. The electrical properties of sintered samples were carried out.
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Background Some children with juvenile idiopathic arthritis either do not respond, or are intolerant to, treatment with disease-modifying antirheumatic drugs, including anti-tumour necrosis factor (TNF) drugs. We aimed to assess the safety and efficacy of abatacept, a selective T-cell costimulation modulator, in children with juvenile idiopathic arthritis who had failed previous treatments.Methods We did a double-blind, randomised controlled withdrawal trial between February, 2004, and June, 2006. We enrolled 190 patients aged 6-17 years, from 45 centres, who had a history of active juvenile idiopathic arthritis; at least five active joints; and an inadequate response to, or intolerance to, at least one disease-modifying antirheumatic drug. All 190 patients were given 10 mg/kg of abatacept intravenously in the open-label period of 4 months. of the 170 patients who completed this lead-in course, 47 did not respond to the treatment according to predefined American College of Rheumatology (ACR) paediatric criteria and were excluded. of the patients who did respond to abatacept, arthritis, and 62 were randomly assigned to receive placebo at the same dose and timing. The primary endpoint was time to flare of arthritis. Flare was defined as worsening of 30% or more in at least three of six core variables, with at least 30% improvement in no more than one variable. We analysed all patients who were treated as per protocol. This trial is registered, number NCT00095173.Findings Flares of arthritis occurred in 33 of 62 (53%) patients who were given placebo and 12 of 60 (20%) abatacept patients during the double-blind treatment (p=0.0003). Median time to flare of arthritis was 6 months for patients given placebo (insufficient events to calculate IQR); insufficient events had occurred in the abatacept group for median time to flare to be assessed (p=0.0002). The risk of flare in patients who contined abatacept was less than a third of that for controls during that double-blind period (hazard ratio 0.31, 95% CI 0.16-0.95). During the double-blind period, the frequency of adverse events did not differ in the two treatment groups, Adverse events were recorded in 37 abatacept recipients (62%) and 34 (55%) placebo recipients (p=0.47); only two serious adverse events were reported, bouth in controls (p=0.50).Interpretation Selective modulation of T-cell costimulation with abatacept is a rational alternative treatment for children with juvenile idiopathic arthritis.Funding Bristol-Myers Squibb.
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The Araes gold deposit, located in eastern Mato Grosso State, central Brazil, is hosted in Neoproterozoic volcanosedimentary rocks of the Paraguay belt, which formed during collision of the Amazonian craton and the Rio Apa block. Ar-40/Ar-39 geochronology and Pb and S isotopic analyses constrain the timing and sources of mineralization. Three biotite flakes from two samples of metavolcanic host rock yield Ar-40/Ar-39 plateau ages between 5941 and 531 Ma, interpreted as cooling ages following regional metamorphism. Clay minerals from a hydrothermal alteration zone yield an Ar-40/Ar-39 integrated age of 503 +/- 3 Ma. Galena grains from ore-bearing veins yield values of Pb-206/(204)pb from 17.952 to 18.383, Pb-207/Pb-204 from 15.156 to 15.811, and Pb-208/Pb-204 from 38.072 to 39.681. Pyrite grains from ore-bearing veins yield values of Pb-206/Pb-204 from 18.037 to 18.202, Pb-207/Pb-204 from 15.744 to 15.901., and Pb-208/(204)pb from 38.338 to 38.800. Pb isotope variations may be explained in terms of mixing a less radiogenic lead component (mu similar to 8.4) from mafic and ultramafic basement host-rocks (Nova Xavantina metavolcanosedimentary rocks) and a more radiogenic lead component (mu similar to 9.2) probably derived from supracrustal rocks (Cuiaba sedimentary groups). Sulfur isotope compositions are homogeneous, with delta S-34 values ranging from -1.1 parts per thousand to 0.9 parts per thousand (galena) and -0.7 parts per thousand to 0.9 parts per thousand (pyrite), suggesting a mantle-derived reservoir for the mineralizing solutions. Based on the Ar, Pb, and S isotope data, we suggest that the precious metals were remobilized from metavolcanic host rocks by hydrothermal solutions during Brasilide-Panafrican regional metamorphism. The Arabs gold deposit probably formed during a late stage of the orogeny, coeval with other mineralization events in the Paraguay Belt.
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The unique carbohydrate-binding property of lectins makes them invaluable tools in biomedical research. Here, we report the purification, partial primary structure, carbohydrate affinity characterization, crystallization, and preliminary X-ray diffraction analysis of a lactose-specific lectin from Cymbosema roseum seeds (CRLII). Isolation and purification of CRLII was performed by a single step using a Sepharose-4B-lactose affinity chromatography column. The carbohydrate affinity characterization was carried using assays for hemagglutination activity and inhibition. CRLII showed hemagglutinating activity toward rabbit erythrocytes. O-glycoproteins from mucine mucopolysaccharides showed the most potent inhibition capacity at a minimum concentration of 1.2 A mu g mL(-1). Protein sequencing by mass spectrometry was obtained by the digestion of CRLII with trypsin, Glu-C, and AspN. CRLII partial protein sequence exhibits 46% similarity with the ConA-like alpha chain precursor. Suitable protein crystals were obtained with the hanging-drop vapor-diffusion method with 8% ethylene glycol, 0.1 M Tris-HCl pH 8.5, and 11% PEG 8,000. The monoclinic crystals belong to space group P2(1) with unit cell parameters a = 49.4, b = 89.6, and c = 100.8 A....
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The polysaccharide antigen from P. brasiliensis has been largely employed in serologic tests, as well as in skin tests, to evaluate cellular immunity. SDS-PAGE analysis of this antigen has revealed a variability in the number of bands exhibited by isolates SN, 265, 339, 113 and 18 (7 to 16 bands). The antigens obtained from isolates 2, PTL, 192 and Adel showed two or three bands. Glycoprotein analysis demonstrated a broad region between 50 and 90 kDa. Major bands of 48 and 30 kDa were present in almost all antigens. Optimal complement fixing dilution appears to be unaffected by the number of bands presented by different antigens. The immunoblot analysis revealed that the 90 and 30 kDa bands were mainly recognized by sera from paracoccidioidomycosis patients. Bands of high molecular weight were also recognized by most of the sera studied. Sera from histoplasmosis recognized the 94 kDa band. In conclusion, although the isolates exhibit quantitative variability in the number of fractions, it is possible to use only one or two samples given the greatest frequency of reactivity is seen in the 30 and 90 kDa fractions.
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The Weyl-Wigner prescription for quantization on Euclidean phase spaces makes essential use of Fourier duality. The extension of this property to more general phase spaces requires the use of Kac algebras, which provide the necessary background for the implementation of Fourier duality on general locally compact groups. Kac algebras - and the duality they incorporate - are consequently examined as candidates for a general quantization framework extending the usual formalism. Using as a test case the simplest nontrivial phase space, the half-plane, it is shown how the structures present in the complete-plane case must be modified. Traces, for example, must be replaced by their noncommutative generalizations - weights - and the correspondence embodied in the Weyl-Wigner formalism is no longer complete. Provided the underlying algebraic structure is suitably adapted to each case, Fourier duality is shown to be indeed a very powerful guide to the quantization of general physical systems.
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Transformation of pesticides is directly related to the environmental conditions during application and transport of these compounds in the ecosystem. Rice fields include peculiar conditions, relatively high temperatures and wet conditions, leading to degradation processes, different from that observed in other agricultural systems. This article presents the degradation routes of some characteristic rice insecticides and herbicides under field conditions. A compilation of the pesticides that are usually applied during rice cultivation is included, with their main physico-chemical parameters. The stability of the pesticides by solid phase extraction systems during storage of rice samples is also discussed.
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Purpose: This investigation studied the effects of 3 surface treatments on the shear bond strength of a light-activated composite resin bonded to acrylic resin denture teeth. Materials and Methods: The occlusal surfaces of 30 acrylic resin denture teeth were ground flat with up to 400-grit silicon carbide paper. Three different surface treatments were evaluated: (1) the flat ground surfaces were primed with methyl methacrylate (MMA) monomer for 180 seconds; (2) light-cured adhesive resin was applied and light polymerized according to the manufacturer's instructions; and (3) treatment 1 followed by treatment 2. The composite resin was packed on the prepared surfaces using a split mold. The interface between tooth and composite was loaded at a cross-head speed of 0.5 mm/min until failure. Results: Analysis of variance indicated significant differences between the surface treatments. Results of mean comparisons using Tukey's test showed that significantly higher shear bond strengths were developed by bonding composite resin to the surfaces that were previously treated with MMA and then with the bonding agent when compared to the other treatments. Conclusion: Combined surface treatment of MMA monomer followed by application of light-cured adhesive resin provided the highest shear bond strength between composite resin and acrylic resin denture teeth.