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1.
Braz. j. med. biol. res ; 39(3): 313-320, Mar. 2006.
Artigo em Inglês | LILACS | ID: lil-421361

RESUMO

Normal central nervous system development relies on accurate intrinsic cellular programs as well as on extrinsic informative cues provided by extracellular molecules. Migration of neuronal progenitors from defined proliferative zones to their final location is a key event during embryonic and postnatal development. Extracellular matrix components play important roles in these processes, and interactions between neurons and extracellular matrix are fundamental for the normal development of the central nervous system. Guidance cues are provided by extracellular factors that orient neuronal migration. During cerebellar development, the extracellular matrix molecules laminin and fibronectin give support to neuronal precursor migration, while other molecules such as reelin, tenascin, and netrin orient their migration. Reelin and tenascin are extracellular matrix components that attract or repel neuronal precursors and axons during development through interaction with membrane receptors, and netrin associates with laminin and heparan sulfate proteoglycans, and binds to the extracellular matrix receptor integrins present on the neuronal surface. Altogether, the dynamic changes in the composition and distribution of extracellular matrix components provide external cues that direct neurons leaving their birthplaces to reach their correct final location. Understanding the molecular mechanisms that orient neurons to reach precisely their final location during development is fundamental to understand how neuronal misplacement leads to neurological diseases and eventually to find ways to treat them.


Assuntos
Humanos , Movimento Celular/fisiologia , Cerebelo/embriologia , Proteínas da Matriz Extracelular/fisiologia , Matriz Extracelular/fisiologia , Neurônios/fisiologia , Moléculas de Adesão Celular Neuronais/fisiologia , Proteínas do Tecido Nervoso/fisiologia , Transdução de Sinais/fisiologia
2.
Ludovica pediátr ; 7(2): 38-50, ago. 2005. ilus
Artigo em Espanhol | LILACS | ID: lil-421990

RESUMO

La hipoxia- isquemica es la principal causa de injuria del sistema nerviosos central en el feto y en el recién nacido, situación agravada, en algunas circunstancias, por infección intrauterina y respuesta inflamatoria fetal. La reducción en las cifras de mortalidad ha producido un incremento de morbilidad, la posibilidad de asistir a las secuelas de aquellas lesiones. En el niño pretérmino que sobrevive, el sustrato morfológico más frecuente de parálisis cerebral es la lucoencefalomalacia pereventricular, la cual forma parte de un expectro más amplio. Las secuelas son déficit en la mielinización, la pérdida de volúmen de sustancia blanca con consecuente ventriculomegalia, el compromiso de vías largas relacionado con el déficit motor del cuadro clínico de páralisis cerebral. En este artículo se sitúa a la leucoencefalomalacia periventricular en el expectro de lesiones hipóxico, isquémica del recién nacido, se detallan sus características clínicas y macra-microscópicas, y se comentan los recientes aportes de la fisiopatología celular. El rol principal del glutamato, la teoría de la excototoxicidad, las citoquinas, y la cascada inflamatoria operan a través de ventanas de vulnerabilidad, que exponen a la oligodendroglia como target esencial, y a la apoptosis como un mecanismo importante de lesión cerebral


Assuntos
Humanos , Gravidez , Apoptose , Hipóxia , Isquemia , Leucomalácia Periventricular , Moléculas de Adesão Celular Neuronais , Oligodendroglia , Moléculas de Adesão Celular Neuronais/análise , Moléculas de Adesão Celular Neuronais/classificação , Necrose
4.
An. acad. bras. ciênc ; 72(3): 381-8, Sept. 2000. ilus, graf
Artigo em Inglês | LILACS | ID: lil-269389

RESUMO

The cell adhesion molecule Rst-irreC is a transmembrane glycoprotein of the immunoglobulin superfamily involved in several important developmental processes in Drosophila, including axonal pathfinding in the optic lobe and programmed cell death and pigment cell differentiation in the pupal retina. As an initial step towards the "in vivo" functional analysis of this protein we have generated transgenic fly stocks carrying a truncated cDNA construct encoding only the extracellular domain of Rst-IrreC under the transcriptional control of the heat shock inducible promoter hsp70. We show that heat-shocking embryos bearing the transgene during the first 8hs of development lead to a 3-4 fold reduction in their viability compared to wild type controls. The embryonic lethality can already be produced by applying the heat pulse in the first 3hs of embryonic development, does not seem to be suppressed in the absence of wildtype product and is progressively reduced as the heat treatment is applied later in embryogenesis. These results are compatible with the hypothesis of the lethal phenotype being primarily due to heterophilic interactions between Rst-IrreC extracellular domain and an yet unknown ligand.


Assuntos
Animais , Masculino , Feminino , Moléculas de Adesão Celular Neuronais/genética , Drosophila melanogaster/genética , Embrião não Mamífero/fisiologia , Expressão Gênica , Genes Letais/fisiologia , Transgenes/fisiologia , Moléculas de Adesão Celular Neuronais/fisiologia , Genes de Insetos/genética , Temperatura Alta , Fenótipo , Choque
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