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Search Results: 1 - 10 of 5497 matches for " PONSODA XAVIER "
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The lizard cerebral cortex as a model to study neuronal regeneration
LOPEZ-GARCIA CARLOS,MOLOWNY ASUNCION,NACHER JUAN,PONSODA XAVIER
Anais da Academia Brasileira de Ciências , 2002,
Abstract: The medial cerebral cortex of lizards, an area homologous to the hippocampal fascia dentata, shows delayed postnatal neurogenesis, i.e., cells in the medial cortex ependyma proliferate and give rise to immature neurons, which migrate to the cell layer. There, recruited neurons differentiate and give rise to zinc containing axons directed to the rest of cortical areas, thus resulting in a continuous growth of the medial cortex and its zinc-enriched axonal projection. This happens along the lizard life span, even in adult lizards, thus allowing one of their most important characteristics: neuronal regeneration. Experiments in our laboratory have shown that chemical lesion of the medial cortex (affecting up to 95% of its neurons) results in a cascade of events: first, massive neuronal death and axonal-dendritic retraction and, secondly, triggered ependymal-neuroblast proliferation and subsequent neo-histogenesis and regeneration of an almost new medial cortex, indistinguishable from a normal undamaged one. This is the only case to our knowledge of the regeneration of an amniote central nervous centre by new neuron production and neo-histogenesis. Thus the lizard cerebral cortex is a good model to study neuronal regeneration and the complex factors that regulate its neurogenetic, migratory and neo-synaptogenetic events.
Overview of the computerized adaptive testing special section.
Ponsoda V.
Psicológica , 2000,
Abstract:
Overview of the computerized adaptive testing special section
Vicente Ponsoda
Psicológica , 2000,
Abstract: Presentación de la sección monográfica sobre test adaptativos informatizados. Este artículo proporciona una visión conjunta de la sección especial de Psicológica sobre tests adaptativos informatizados. Se presenta también una breve introducción al tema. De cada artículo se muestran sus principales resultados, las conexiones con los demás trabajos de la sección especial y el tema de investigación con el que está más relacionado.
Pterostilbene-Induced Tumor Cytotoxicity: A Lysosomal Membrane Permeabilization-Dependent Mechanism
Salvador Mena, María L. Rodríguez, Xavier Ponsoda, José M. Estrela, Marja J??ttela, Angel L. Ortega
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044524
Abstract: The phenolic phytoalexin resveratrol is well known for its health-promoting and anticancer properties. Its potential benefits are, however, limited due to its low bioavailability. Pterostilbene, a natural dimethoxylated analog of resveratrol, presents higher anticancer activity than resveratrol. The mechanisms by which this polyphenol acts against cancer cells are, however, unclear. Here, we show that pterostilbene effectively inhibits cancer cell growth and stimulates apoptosis and autophagosome accumulation in cancer cells of various origins. However, these mechanisms are not determinant in cell demise. Pterostilbene promotes cancer cell death via a mechanism involving lysosomal membrane permeabilization. Different grades of susceptibility were observed among the different cancer cells depending on their lysosomal heat shock protein 70 (HSP70) content, a known stabilizer of lysosomal membranes. A375 melanoma and A549 lung cancer cells with low levels of HSP70 showed high susceptibility to pterostilbene, whereas HT29 colon and MCF7 breast cancer cells with higher levels of HSP70 were more resistant. Inhibition of HSP70 expression increased susceptibility of HT29 colon and MCF7 breast cancer cells to pterostilbene. Our data indicate that lysosomal membrane permeabilization is the main cell death pathway triggered by pterostilbene.
The lizard cerebral cortex as a model to study neuronal regeneration
LOPEZ-GARCIA, CARLOS;MOLOWNY, ASUNCION;NACHER, JUAN;PONSODA, XAVIER;SANCHO-BIELSA, FRANCISCO;ALONSO-LLOSA, GREGORI;
Anais da Academia Brasileira de Ciências , 2002, DOI: 10.1590/S0001-37652002000100006
Abstract: the medial cerebral cortex of lizards, an area homologous to the hippocampal fascia dentata, shows delayed postnatal neurogenesis, i.e., cells in the medial cortex ependyma proliferate and give rise to immature neurons, which migrate to the cell layer. there, recruited neurons differentiate and give rise to zinc containing axons directed to the rest of cortical areas, thus resulting in a continuous growth of the medial cortex and its zinc-enriched axonal projection. this happens along the lizard life span, even in adult lizards, thus allowing one of their most important characteristics: neuronal regeneration. experiments in our laboratory have shown that chemical lesion of the medial cortex (affecting up to 95% of its neurons) results in a cascade of events: first, massive neuronal death and axonal-dendritic retraction and, secondly, triggered ependymal-neuroblast proliferation and subsequent neo-histogenesis and regeneration of an almost new medial cortex, indistinguishable from a normal undamaged one. this is the only case to our knowledge of the regeneration of an amniote central nervous centre by new neuron production and neo-histogenesis. thus the lizard cerebral cortex is a good model to study neuronal regeneration and the complex factors that regulate its neurogenetic, migratory and neo-synaptogenetic events.
Variació lingüística, norma i ensenyament de la llengua
Joan J. Ponsoda
Temps d'Educació , 1996,
Abstract:
Tests informatizados y adaptativos informatizados: investigación en Espa a
Julio Olea,Vicente Ponsoda
Revista Electrónica de Investigación y Evaluación Educativa , 1998,
Abstract: Self-adapted testing: Presentation of special issue
Neurons of the Dentate Molecular Layer in the Rabbit Hippocampus
Francisco J. Sancho-Bielsa,Juan D. Navarro-López,Gregori Alonso-Llosa,Asunción Molowny,Xavier Ponsoda,Javier Yajeya,Carlos López-García
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048470
Abstract: The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals’ life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow and biocytin injections), eight neuronal morphological types have been detected in the molecular layer of developing adult and old rabbits. Six of them appear as interneurons displaying smooth dendrites and GABA immunoreactivity: those here called as globoid, vertical, small horizontal, large horizontal, inverted pyramidal and polymorphic. Additionally there are two GABA negative types: the sarmentous and ectopic granular neurons. The distribution of the somata and dendritic trees of these neurons shows preferences for a definite sublayer of the molecular layer: small horizontal, sarmentous and inverted pyramidal neurons are preferably found in the outer third of the molecular layer; vertical, globoid and polymorph neurons locate the intermediate third, while large horizontal and ectopic granular neurons occupy the inner third or the juxtagranular molecular layer. Our results reveal substantial differences in the morphology and electrophysiological behaviour between each neuronal archetype in the dentate molecular layer, allowing us to propose a new classification for this neural population.
Protein Traffic Is?an Intracellular Target in Alcohol Toxicity
Guillermo Esteban-Pretel,María Pilar Marín,Ana M. Romero,Xavier Ponsoda,Raul Ballestin,Juan J. Canales,Jaime Renau-Piqueras
Pharmaceuticals , 2011, DOI: 10.3390/ph4050741
Abstract: Eukaryotic cells comprise a set of organelles, surrounded by membranes with a unique composition, which is maintained by a complex synthesis and transport system. Cells also synthesize the proteins destined for secretion. Together, these processes are known as the secretory pathway or exocytosis. In addition, many molecules can be internalized by cells through a process called endocytosis. Chronic and acute alcohol (ethanol) exposure alters the secretion of different essential products, such as hormones, neurotransmitters and others in a variety of cells, including central nervous system cells. This effect could be due to a range of mechanisms, including alcohol-induced alterations in the different steps involved in intracellular transport, such as glycosylation and vesicular transport along cytoskeleton elements. Moreover, alcohol consumption during pregnancy disrupts developmental processes in the central nervous system. No single mechanism has proved sufficient to account for these effects, and multiple factors are likely involved. One such mechanism indicates that ethanol also perturbs protein trafficking. The purpose of this review is to summarize our understanding of how ethanol exposure alters the trafficking of proteins in different cell systems, especially in central nervous system cells (neurons and astrocytes) in adult and developing brains.
Structure preserving integrators for solving linear quadratic optimal control problems with applications to describe the flight of a quadrotor
Philipp Bader,Sergio Blanes,Enrique Ponsoda
Mathematics , 2012,
Abstract: We present structure preserving integrators for solving linear quadratic optimal control problems. This problem requires the numerical integration of matrix Riccati differential equations whose exact solution is a symmetric positive definite time-dependent matrix which controls the stability of the equation for the state. This property is not preserved, in general, by the numerical methods. We propose second order exponential methods based on the Magnus series expansion which unconditionally preserve positivity for this problem and analyze higher order Magnus integrators. This method can also be used for the integration of nonlinear problems if they are previously linearized. The performance of the algorithms is illustrated with the stabilization of a quadrotor which is an unmanned aerial vehicle.
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