871 resultados para cultures


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The present thesis is an attempt to understand the role of GABA, GABAA and GABAB receptors in the regulation of liver cell proliferation using in vivo and in vitro models. The work also focuses on the brain GABAergic changes associated with normal and neoplastic cell growth in liver and to delineate its regulatory function. The investigation of mechanisms involving mitogenic models without cell necrosis may contribute our knowledge about both on cell growth, carcinogenesis, liver pathology and treatment. Objectives of the present study are, to induce controlled liver cell proliferation by partial hepatectomy and lead nitrate administration and uncontrolled cell proliferation by N-nitrosodiethylamine treatment in male Wistar rats, the changes in the content of GABA, GABAA,GABAB in various rat brain regions. To study the GABAA and GABAB receptor changes in brain stem, hypothalamus, cerebellum and cerebral cortex during the active cortex during the period of active DNA synthesis in liver of different experimental groups. The changes in GABAA and GABAB receptor function of the brain stem, hypothalamus and cerebellum play an important role sympathetic regulation of cell proliferation and neoplastic growth in liver. The decrease in GABA content in brain stem, hypothalamus and cerebellum during regeneration and neoplasia in liver. The time course of brain GABAergic changes was closely correlated with that of heptic DNA synthesis. The functional significance of these changes was further explored by studying the changes in GABAA and GABAB receptors in brain.

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The adult mammalian liver is predominantly in a quiescent state with respect to cell division. This quiescent state changes dramatically, however, if the liver is injured by toxic, infectious or mechanic agents (Ponder, 1996). Partial hepatectomy (PH) which consists of surgical removal of two-thirds of the liver, has been used to stimulate hepatocyte proliferation (Higgins & Anderson 1931). This experimental model of liver regeneration has been the target of many studies to probe the mechanisms responsible for liver cell growth control (Michalopoulos, 1990; Taub, 1996). After PH most of the remaining cells in the renmant liver respond with co-ordinated waves of DNA synthesis and divide in a process called compensatory hyperplasia. Hence, liver regeneration is a model of relatively synchronous cell cycle progression in vivo. In contrast to hepatomas, cell division is terminated under some intrinsic control when the original cellular mass has been regained. This has made liver regeneration a useful model to dissect the biochemical and molecular mechanisms of cell division regulation. The liver is thus, one of the few adult organs that demonstrates a physiological growth rewonse (Fausto & Mead, 1989; Fausto & Webber, 1994). The regulation of liver cell proliferation involves circulating or intrahepatic factors that are involved in either the priming of hepatocytes to enter the cell cycle (Go to G1) or progression through the cell cycle. In order to understand the basis of liver regeneration it is mandatory to define the mechanisms which (a) trigger division, (b) allow the liver to concurrently grow and maintain dilferentiated fimction and (c) terminate cell proliferation once the liver has reached the appropriate mass. Studies on these aspects of liver regeneration will provide basic insight of cell growth and dilferentiation, liver diseases like viral hepatitis, toxic damage and liver transplant where regeneration of the liver is essential. In the present study, Go/G1/S transition of hepatocytes re-entering the cell cycle after PH was studied with special emphasis on the involvement of neurotransmitters, their receptors and second messenger function in the control of cell division during liver regeneration

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Random genetic changes generated during in vitro culture are not desirable for plant micropropagation and genetic transformation. RAPD markers were used to detect the variation in leaf disc callus cultures of Jatropha curcas, maintained in Murashige and Skoog (MS) medium with different auxin and cytokinin combinations. In total 41 scorable bands were produced with 11 primers. Out of 41 bands, 37 were polymorphic (91.12%). The average number of polymorphic bands was 3.36 per primer. The highest similarity (0.82) with mother plant was seen in callus maintained on MS with hormonal combination Indole butyric acid - 0.4mg/l+ N6-benzyladenine purine - 4.0 mg/l. The callus grown on MS with hormonal combinations IBA- 0.4mg/l+ BAP- 2.0mg/l, IBA- 0.4mg/l+ BAP- 2.5mg/l and IBA- 0.6 mg/l+ BAP- 2.0 mg/l also showed similarity with the mother plant. Callus maintained on MS with hormonal combination IBA- 0.2mg/l+ BAP- 2.0 mg/l was found to show least similarity (0.53) with mother plant

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L’evidència de la multiplicitat de cultures a l’escola planteja molts interrogants sobre la manera com han de ser-hi presents aquestes cultures. Si volem que contribueixin a construir una cultura comuna plenament inserida en el nostre país, com podem convertir les dificultats d’aquest objectiu en clau d’oportunitat?

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Resumen tomado del autor. Se muestra tabla y notas a pie de página. Artículo disponible en castellano y catalán

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Incluido en el número dedicado a inmigración e integración escolar

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Detectar, describir y analizar los procesos de colaboración y las estructuras de participación entre profesores de un instituto de educación secundaria, a raíz de la implementación de la LOGSE y de los nuevos desafíos de la realidad escolar actual. Metodología cualitativa, etnografía escolar, investigación narrativa y estudio de caso único centrado en un instituto de educación secundaria de 350 alumnos y 45 profesores. Análisis de los procesos formales e informales de trabajo no lectivo de los profesores. Interpretación de los datos. Categorización inductiva, proceso simultáneo de recogida y análisis de los datos, validación interna y externa de los resultados y taxonominazión de las informaciones en tres grandes ámbitos: dimensión colaborativa, dimensión institucional y dimensión participativa, de acuerdo con el modelo de Mónica Gather, 2004. Observación participante, entrevistas en profundidad, diario de campo y análisis de documentos. Triangulación, inmersión prolongada en el objeto de estudio durante tres años y descripción exhaustiva del proceso de análisis e interpretación extensiva de las informaciones obtenidas. Procesos espontáneos e informales de colegialidad paralela, desarrollados intensivamente y sin control externo. Procesos colegiados de colaboración de irregular intensidad, duración y contenido, desarrollados en el interior de estructuras verticales y horizontales de participación docente no lectiva. Si bien es difícil especificar un proyecto educativo colectivamente asumido y aplicado, se constata que existe en el centro un grupo estable y predominante de profesores que apoya un proyecto más o menos basado en la idea de equilibrar lo instructivo, con una preocupación concreta por las necesidades escolares del alumnado. Preocupación que se traduce en una relación más personalizada y atenta hacia los educandos. Se refleja no obstante como el profesorado del centro comparte parcialmente aquellos valores y formas de hacer vinculados a aspectos estructurales de sus trabajos, como también en la asunción de referentes educativos interiorizados, culturalmente muy instaurados. Al mismo tiempo es sustancialmente más complejo compartir un proyecto pedagógico de fondo que apele a cuestiones básicas de consenso, referidas a aspectos verdaderamente pedagógicos. Se constata el carácter débil e inarticulado de la cultura del centro analizado.

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El presente material forma parte del programa del Departamento de Dinámica Educativa del Ayuntamiento de Palma de Mallorca

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Resumen del autor en catalán

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Resumen basado en el de los autores

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