986 resultados para Séneca, Lucio Anneo
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Colofón
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Los tejidos residenciales son la componente esencial de nuestras ciudades, en particular si incluimos en ellos no solo los edificios de vivienda sino también los espacios públicos anexos (calles, avenidas, bulevares, plazas y jardines de barrio); así como otros edificios y usos complementarios o compatibles: parcelas destinadas a equipamientos escolares, deportivos, sociales, comerciales etc., a nivel de barrio o de distrito, edificios de oficinas públicos o privados insertos dentro de tramas prioritariamente residenciales, parcelas ocupadas por servicios urbanos imprescindibles (limpieza, bomberos, etc.).
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En este artículo se aplica el modelo de la EHE-08 de carbonatación y de penetración de cloruros a la determinación de la vida útil de conductos de hormigón utilizados en sistemas de saneamiento y drenaje. Asimismo, se presentan de forma sencilla una serie de reglas que pueden contribuir a la mejora del comportamiento de los conductos de hormigón en las condiciones de servicio más frecuentes.
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Los conductos de hormigón durante su vida útil, están sometidos a un conjunto de acciones mecánicas, físicas, químicas y microbiológicas frente a las que deben de diseñarse para soportarlas sin perder sus prestaciones funcionales, de estabilidad mecánica y de estanquidad. Por tanto, las tuberías se deben diseñar y fabricar conforme con unos estándares de calidad adecuados. En este artículo se analizan las acciones mecánicas, físicas y químicas que afectan a los conductos de hormigón utilizados en sistemas de saneamiento y drenaje.
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Este trabalho tem por objetivo traçar o perfil da produção acadêmica sobre a Rede Globo de Televisão. Para isto, utilizamos como fonte de pesquisa teses de doutorado e dissertações de mestrado defendidas em programas de pós-graduação no Brasil e repertoriadas no banco de teses da CAPES. Foram analisadas 145 publicações acadêmicas no período de 1987 a 2006. Na abordagem analítica do perfil desta produção destacam-se: ano de produção; instituição de ensino de origem; região geográfica; nível acadêmico, área de estudo e gênero dos autores.(AU)
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Este trabalho tem por objetivo traçar o perfil da produção acadêmica sobre a Rede Globo de Televisão. Para isto, utilizamos como fonte de pesquisa teses de doutorado e dissertações de mestrado defendidas em programas de pós-graduação no Brasil e repertoriadas no banco de teses da CAPES. Foram analisadas 145 publicações acadêmicas no período de 1987 a 2006. Na abordagem analítica do perfil desta produção destacam-se: ano de produção; instituição de ensino de origem; região geográfica; nível acadêmico, área de estudo e gênero dos autores.(AU)
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Tendo como pano de fundo a confessionalidade da rede adventista de educação presente de maneira marcante no espaço escolar e a intensa diversidade religiosa discente, esta pesquisa analisa a relação de possíveis tensões entre a confessionalidade escolar e a diversidade religiosa presente neste espaço. Leva em consideração o processo de modernidade causadora de importantes transformações na educação, na religião e na forma dos dois institutos se relacionarem. Levou-se em consideração o perfil socioeconômico e religioso dos alunos e possíveis tensões na recepção do religioso no espaço escolar adventista por parte dos discentes, inclusive por aqueles que se declaram adventistas. O espaço escolhido para esta pesquisa foi o de colégios adventistas localizadas no contexto do ABCD Paulista, que ofertam o Ensino Médio. Estas unidades escolares estão situadas nas cidades de Diadema, Santo André e São Caetano do Sul, cidades localizadas na mesma microrregião, mas com distintas realidades socioeconômicas
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The development of gene-replacement therapy for inborn errors of metabolism has been hindered by the limited number of suitable large-animal models of these diseases and by inadequate methods of assessing the efficacy of treatment. Such methods should provide sensitive detection of expression in vivo and should be unaffected by concurrent pharmacologic and dietary regimens. We present the results of studies in a neonatal bovine model of citrullinemia, an inborn error of urea-cycle metabolism characterized by deficiency of argininosuccinate synthetase and consequent life-threatening hyperammonemia. Measurements of the flux of nitrogen from orally administered 15NH4 to [15N]urea were used to determine urea-cycle activity in vivo. In control animals, these isotopic measurements proved to be unaffected by pharmacologic treatments. Systemic administration of a first-generation E1-deleted adenoviral vector expressing human argininosuccinate synthetase resulted in transduction of hepatocytes and partial correction of the enzyme defect. The isotopic method showed significant restoration of urea synthesis. Moreover, the calves showed clinical improvement and normalization of plasma glutamine levels after treatment. The results show the clinical efficacy of treating a large-animal model of an inborn error of hepatocyte metabolism in conjunction with a method for sensitively measuring correction in vivo. These studies will be applicable to human trials of the treatment of this disorder and other related urea-cycle disorders.
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A cellular protein, previously described as p35/38, binds to the complementary (−)-strand of the leader RNA and intergenic (IG) sequence of mouse hepatitis virus (MHV) RNA. The extent of the binding of this protein to IG sites correlates with the efficiency of the subgenomic mRNA transcription from that IG site, suggesting that it is a requisite transcription factor. We have purified this protein and determined by partial peptide sequencing that it is heterogeneous nuclear ribonucleoprotein (hnRNP) A1, an abundant, primarily nuclear protein. hnRNP A1 shuttles between the nucleus and cytoplasm and plays a role in the regulation of alternative RNA splicing. The MHV(−)-strand leader and IG sequences conform to the consensus binding motifs of hnRNP A1. Recombinant hnRNP A1 bound to these two RNA regions in vitro in a sequence-specific manner. During MHV infection, hnRNP A1 relocalizes from the nucleus to the cytoplasm, where viral replication occurs. These data suggest that hnRNP A1 is a cellular factor that regulates the RNA-dependent RNA transcription of the virus.
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Human ether-a-gogo related gene (HERG) K+ channels are key elements in the control of cell excitability in both the cardiovascular and the central nervous systems. For this reason, the possible modulation by reactive oxygen species (ROS) of HERG and other cloned K+ channels expressed in Xenopus oocytes has been explored in the present study. Exposure of Xenopus oocytes to an extracellular solution containing FeSO4 (25–100 μM) and ascorbic acid (50–200 μM) (Fe/Asc) increased both malondialdehyde content and 2′,7′-dichlorofluorescin fluorescence, two indexes of ROS production. Oocyte perfusion with Fe/Asc caused a 50% increase of the outward K+ currents carried by HERG channels, whereas inward currents were not modified. This ROS-induced increase in HERG outward K+ currents was due to a depolarizing shift of the voltage-dependence of channel inactivation, with no change in channel activation. No effect of Fe/Asc was observed on the expressed K+ currents carried by other K+ channels such as bEAG, rDRK1, and mIRK1. Fe/Asc-induced stimulation of HERG outward currents was completely prevented by perfusion of the oocytes with a ROS scavenger mixture (containing 1,000 units/ml catalase, 200 ng/ml superoxide dismutase, and 2 mM mannitol). Furthermore, the scavenger mixture also was able to reduce HERG outward currents in resting conditions by 30%, an effect mimicked by catalase alone. In conclusion, the present results seem to suggest that changes in ROS production can specifically influence K+ currents carried by the HERG channels.
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Polymorphonuclear leukocytes are essential for host defense to infectious diseases. CCAAT/enhancer binding protein ɛ (C/EBPɛ) is preferentially expressed in granulocytes and lymphoid cells. Mice with a null mutation in C/EBPɛ develop normally and are fertile but fail to generate functional neutrophils and eosinophils. Opportunistic infections and tissue destruction lead to death by 3–5 months of age. Furthermore, end-stage mice develop myelodysplasia, characterized by proliferation of atypical granulocytes that efface the bone marrow and result in severe tissue destruction. Thus, C/EBPɛ is essential for terminal differentiation and functional maturation of committed granulocyte progenitor cells.
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We describe the application of 59Co NMR to the study of naturally occurring cobalamins. Targets of these investigations included vitamin B12, the B12 coenzyme, methylcobalamin, and dicyanocobyrinic acid heptamethylester. These measurements were carried out on solutions and powders of different origins, and repeated at a variety of magnetic field strengths. Particularly informative were the solid-state central transition NMR spectra, which when combined with numerical line shape analyses provided a clear description of the cobalt coupling parameters. These parameters showed a high sensitivity to the type of ligands attached to the metal and to the crystallization history of the sample. 59Co NMR determinations also were carried out on synthetic cobaloximes possessing alkyl, cyanide, aquo, and nitrogenated axial groups, substituents that paralleled the coordination of the natural compounds. These analogs displayed coupling anisotropies comparable to those of the cobalamins, as well as systematic up-field shifts that can be rationalized in terms of their stronger binding affinity to the cobalt atom. Cobaloximes also displayed a higher regularity in the relative orientations of their quadrupole and shielding coupling tensors, reflecting a higher symmetry in their in-plane coordination. For the cobalamines, poor correlations were observed between the values measured for the quadrupole couplings in the solid and the line widths observed in the corresponding solution 59Co NMR resonances.
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Inclui notas explicativas, bibliográficas e bibliografia
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Aging in vivo and cell division in vitro are associated with telomere shortening. Several lines of evidence suggest that telomere length may be a good predictor of the long term replicative capacity of cells. To investigate the natural fate of chromosome telomeres of hematopoietic stem cells in vivo, we measured the telomere length of peripheral blood granulocytes from 11 fully engrafted bone marrow transplant recipients and from their respective donors. In 10 of 11 donor–recipient pairs, the telomere length was significantly reduced in the recipient and the extent of reduction correlated inversely with the number of nucleated cells infused. These data provide internally controlled in vivo evidence that, concomitantly with their proliferation, hematopoietic stem cells lose telomere length; it is possible that, as a result, their proliferative potential is reduced. These findings must be taken into account when developing new protocols in which few stem cells are used for bone marrow transplantation or for gene therapy.