CBME

As in mammals, estrogens in fish are essential for reproduction but also important regulators of mineral homeostasis. Fish scales are a non-conventional target tissue responsive to estradiol and constitute a good model to study mineralized tissues effects and mechanisms of action of estrogenic compounds, including phytoestrogens. The responsiveness to estradiol and the phytoestrogen genistein, was compared between the scales and the liver, a classical estrogenic target, in sea bass (Dicentrarchus labrax). Injection with estradiol and genistein significantly increased circulating vitellogenin (for both compounds) and mineral levels (estradiol only) and genistein also significantly increased scale enzymatic activities suggesting it increased mineral turnover. The repertoire, abundance and estrogenic regulation of nuclear estrogen receptors (ESR1, 2a and 2b) and membrane G-protein receptors (GPER and GPER-like) were different between liver and scales, which presumably explains the tissue-specific changes detected in estrogen-responsive gene expression. In scales changes in gene expression mainly consisted of small rapid increases, while in liver strong, sustained increases/decreases in gene expression occurred. Similar but not overlapping gene expression changes were observed in response to both estradiol and genistein. This study demonstrates for the first time the expression of membrane estrogen receptors in scales and that estrogens and phytoestrogens, to which fish may be exposed in the wild or in aquaculture, both affect liver and mineralized tissues in a tissue-specific manner.

In the adult mammalian brain, new neurons continue to be produced throughout life in two main regions in the brain, the subgranular zone (SGZ) in the hippocampus and the subventricular zone in the walls of the lateral ventricles. Neural stem cells (NSCs) proliferate in these niches, and migrate as neuroblasts, to further differentiate in locations where new neurons are needed, either in normal or pathological conditions. However, the endogenous attempt of brain repair is not very efficient. Calpains are proteases known to be involved in neuronal damage and in cell proliferation, migration and differentiation of several cell types, though their effects on neurogenesis are not well known. Previous work by our group has shown that the absence of calpastatin (CAST), the endogenous inhibitor of calpains, impairs early stages of neurogenesis. Since the hippocampus is highly associated with learning and memory, we aimed to evaluate whether calpain inhibition would help improve cognitive re...

Nitric oxide (NO) is involved in the upregulation of endogenous neurogenesis in the subventricular zone and in the hippocampus after injury. One of the main neurogenic pathways activated by NO is the ERK/MAPK pathway, downstream of the EGF receptor. However, the mechanism by which NO stimulates cell proliferation through activation of the ERK/MAPK pathway remains unknown, although p21Ras seems to be one of the earliest targets of NO. Here, we aimed to study the possible neurogenic action of NO by post-translational modification of p21Ras as a relevant target for early neurogenic events promoted by NO in neural stem cells (NSC). We show that NO caused S-nitrosylation of p21Ras in Cys118, which triggered downstream activation of the ERK/MAPK pathway and proliferation of NSC. Moreover, in cells overexpressing a mutant Ras in which Cys118 was replaced by a serine -C118S-, cells were insensitive to NO, and no increase in S-nitrosylation, in ERK phosphorylation or in cell proliferation we...

Foram várias as pessoas que ao longo dos meses de construção se envolveram e se entusiasmaram com este trabalho. Em primeiro lugar, um agradecimento ao orientador de estágio Dr. Luis Cruz pelo envolvimento activo e acompanhamento científico desta dissertação e ao co-orientador, Prof. Doutor António Ferreira pela presença nos momentos chave. Da Faculdade de Medicina Veterinária de Lisboa, queria agradecer ao Dr. Nuno Felix e ao Prof. Sales Luís, pelo contributo e orientações. Um agradecimento muito especial pela amizade e disponibilidade constantes ao Prof. Doutor David Tavares, pela perspectiva das ciências sociais; os seus conselhos e palavras foram totalmente absorvidos e considerados por mim. Também da Escola Superior de Tecnologia da Saúde de Lisboa, agradeço à Mestre Rute Borrego pelo carinho e ajuda e à Mestre Joana Sousa, pelas dicas preciosas sobre estatística e SPSS. Agradeço a disponibilidade de todos os inquiridos, de norte a sul do país e além fronteiras, cuja receptividade permitiu a concretização deste trabalho. Agradeço a todos os familiares e amigos que me ouviram as convicções, dúvidas e incertezas, em particular ao meu "huby" Filipe Veloso Gomes, sempre com um espírito científico extraordinariamente apurado e assertivo e à minha filósofa e confidente Sofia Alexandre pelos anos de discussão sobre a moral e a "moraleja", o certo e o errado. Em questões mais práticas, agradeço ao informático Diogo Alexandre pela sua tranquilidade e convicção nas novas tecnologias. Uma nota para a biblioteca da Faculdade de Medicina Veterinária de Lisboa, onde consultei alguns livros da área, biblioteca da Escola Superior de Tecnologias da Saúde de Lisboa, onde consultei livros sobre investigação e de ciências sociais e humanas e biblioteca central do campus de Gambelas da Universidade do Algarve (Faro), onde consultei livros de ciências sociais e humanas e passei horas a redigir texto. Uma referência também para a Clínica Veterinária das Laranjeiras, onde pude consultar livros de emergência e cuidados críticos de veterinária tão actuais quanto possível, e para a Clínica de Cardiologia e Medicina Desportiva Veloso Gomes (Faro), onde consultei livros de medicina humana. Por fim, queria dedicar o empenho que confiei a este trabalho ao Feijãozinho, que apesar da sua fugaz aparição, deixou a promessa de um futuro incerto mas cheio de presença e alegria. Palavras-chave: paragem cardiopulmonar, ressuscitação cardiopulmonar, decisão de não-reanimação vi vii "Perceptions and professional practices of Portuguese veterinarians towards cardiopulmonarycerebral resuscitation"