Search

The therapeutic effect of three polyvinyl alcohol (PVA) membranes loaded with electrically conductive materials - carbon nanotubes (PVA-CNTs) and polypyrrole (PVA-PPy) - were tested in vivo for neuro-muscular regeneration after an axonotmesis injury in the rat sciatic nerve. The membranes electrical conductivity measured was 1.5 ± 0.5 × 10

Mesenchymal stem cells are posing as a promising character in the most recent therapeutic strategies and, since their discovery, extensive knowledge on their features and functions has been gained. In recent years, innovative sources have been disclosed in alternative to the bone marrow, conveying their associated ethical concerns and ease of harvest, such as the umbilical cord tissue and the dental pulp. These are also amenable of cryopreservation and thawing for desired purposes, in benefit of the donor itself or other patients in pressing need. These sources present promising possibilities in becoming useful cell sources for therapeutic applications in the forthcoming years. Effective and potential applications of these cellular-based strategies for the regeneration of peripheral nerve are overviewed, documenting recent advances and identified issues for this research area in the near future. Finally, besides the differentiation capacities attributed to mesenchymal stem cells, advances in the recognition of their effective mode of action in the regenerative theatre have led to a new area of interest: the mesenchymal stem cells’ secretome. The paracrine modulatory pathway appears to be a major mechanism by which these are beneficial to nerve regeneration and comprehension on the specific growth factors, cytokine, and extracellular molecules secretion profiles is therefore of great interest.

O objetivo do presente trabalho é problematizar o papel da Rússia enquanto economia emergente. É nossa opinião que a Rússia não é uma economia emergente, no sentido tradicional do conceito, normalmente associado aos BRICS (Brasil, Rússia, India, China e África do Sul), mas antes uma economia reemergente. Existem vários elementos de dissociação da visão tradicional que se tem dos países emergentes, elementos esses que colocam a Rússia numa posição de reemergência não só de poder económico como também político. Abordar-se-á o conceito numa perspetiva ampla, analisando não só elementos exclusivamente económicos mas também políticos e inclusive militares.Apesar de todo o poder estratégico russo, a perda de influência global e uma economia a braços com vários problemas, tornam difícil a classificação da Rússia como uma potência emergente semelhante à China ou à India. Ao contrário das restantes economias emergentes, a Rússia não evidencia um crescimento demográfico capaz de sustentar as suas ambições económicas e políticas. Também os valores de crescimento do PIB se encontram muito longe do esperado numa economia emergente.Se a Rússia é considerada uma potência reemergente, deve-o em grande parte à vantagem energética que lhe permite ter uma influência regional decisiva e é um dos instrumentos de poder económico e político sobre toda a Europa.Nos últimos anos, a Rússia parece ter sentido a necessidade de procurar novos aliados,para poder conquistar novamente o seu espaço no mercado internacional. Os russos fortaleceram as relações com os BRICS e em particular com a China, numa tentativa de se tornarem não apenas potências regionais, mas verdadeiras potências globais.

Relatório de Estágio apresentado à Escola Superior de Educação do Instituto Politécnico de Castelo Branco para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Educação Pré-Escolar e Ensino do 1º Ciclo do Ensino Básico. Este Relatório de Estágio apresenta uma componente relacionada com as Práticas Supervisionadas em Educação Pré-Escolar e em 1º Ciclo do Ensino Básico e outra relacionada com o estudo sobre o Desenvolvimento de Competências Sociais em Contexto Pré-Escolar, projeto de investigação implementado no âmbito da Prática Supervisionada em Educação Pré-escolar. A escolha desta temática deve-se ao facto das competências sociais terem vindo a ganhar importância desde os anos 70 do passado século, visto que o adequado desenvolvimento das mesmas influencia positivamente a vida futura das crianças. Como opção metodológica selecionámos a investigação-ação, que permite relacionar a ação com a investigação, recorrendo a um processo cíclico que alterna entre a ação e a reflexão crítica, passando pela observação e pela planificação. Os participantes do estudo são crianças, com idades compreendidas entre os três e os quatro anos, que frequentam o jardim-de-infância onde foi implementada a Prática Supervisionada em Educação Pré-escolar. De modo a compreendermos quais as dimensões das competências sociais que as crianças de três ou quatro anos têm ou não desenvolvidas, preenchemos escalas de observação de comportamentos. Após a análise de resultados, implementámos algumas atividades de promoção de competências sociais baseadas num programa previamente aplicado, comparando depois os resultados obtidos nas escalas de observação antes e após as atividades. A família é um dos focos deste estudo, pois esta é considerada como o primeiro agente socializador da criança. O Jardim de Infância surge por ser um dos locais onde as crianças passam a maior parte do seu tempo e por ser aqui que estas desenvolvem as suas relações sociais. This internship Report presents a component related to the Supervised Practice in Pre-School Education and in 1st Cycle of Basic Education, and other related to the study on the development of Social Competence in school context, research project implemented within the framework of supervised practice in Pre-School Education. The choice of this theme is because social skills have been gaining importance since the '70 of the past century, whereas the proper development of the same influences positively the future life of children. As a methodological option was selected the research-action, which allows you to relate the action with research, using a cyclic process that alternates between action and critical reflection through observation and by planning. Study participants are children, aged between three and four years, who attend the kindergarten where implemented the supervised practice in Pre-School Education. In order to understand what the dimensions of the social skills that children of three or four years have not developed or were filled scales of observation of behaviors. After analysis of results, have implemented some social competence promotion activities based on a program previously applied, comparing the results obtained after the scales of observation before and after the activities. The family is one of the focuses of this study, as this is considered as the first child's socializing agent. The kindergarten is for being one of the places where children spend most of their time and for being here that these develop their social relations.

Polyvinyl alcohol hydrogel (PVA) is a water-soluble synthetic polymer with an increasingly use in biomedical applications including vascular grafting. It was argued that the copolymerization of PVA with dextran (Dx) can result in an improvement of blood/biomaterial interactions. The focus of this experimental work is to assess that interaction through an in vivo and in vitro evaluation of the coagulation system activation. The thrombogenicity of the copolymer was determined by quantification of the adhered platelets, by the lactate dehydrogenase assay (LDH), quantification of whole blood clotting time and by quantification of platelet activation assessed by flow cytometry. The thrombin-antithrombin complex value was also determined. The obtained results for the in vitro assays suggested a non-thrombogenic profile for PVA/Dx. Additionally; the in vivo determinations were focused in the coagulation and hematological profile assessment in the animal model (sheep) after PVA/Dx vascular graft implantation. For coagulation homeostasis assessment, the intrinsic and extrinsic pathway activation was measured by the determination of prothrombin time (PT), activated partial thromboplastin time (APTT). Other coagulation activation and inflammatory markers like D-dimers, interleukin-6 (IL-6) and C-reactive protein (CRP) were also assessed. The PVA/Dx (90/10, v/v) copolymer tended to inhibit the platelet adhesion/activation process and the contact activation process for coagulation. Those results were also confirmed with the in vivo experiments where the measurements for APTT, IL-6 and CRP parameters were normal considering the species normal range values. The response to those events is an indicator of the in vitro and in vivo hemocompatibility of PVA/Dx and it allows us to select this biomaterial for further pre-clinical trials in vascular reconstruction.

Polyvinyl alcohol hydrogel (PVA) is a synthetic polymer with an increasing application in the biomedical field that can potentially be used for vascular grafting. However, the tissue and blood–material interactions of such gels and membranesare unknown in detail. The objectives of this study were to: (a) assess the biocompatibility and (b) hemocompatibility of PVA-based membranes in order to get some insight into its potential use as a vascular graft. PVA was evaluated isolated or in copolymerization with dextran (DX), a biopolymer with known effects in blood coagulation homeostasis.

Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to assess the effect on nerve regeneration, associating a hybrid chitosan membrane with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord, in peripheral nerve reconstruction after crush injury. Chromosome analysis on human mesenchymal stem cell line from Wharton's jelly was carried out and no structural alterations were found in metaphase. Chitosan membranes were previously tested in vitro, to assess their ability in supporting human mesenchymal stem cell survival, expansion, and differentiation. For the in vivo testing, Sasco Sprague adult rats were divided in 4 groups of 6 or 7 animals each: Group 1, sciatic axonotmesis injury without any other intervention (Group 1-Crush); Group 2, the axonotmesis lesion of 3 mm was infiltrated with a suspension of 1 250–1 500 human mesenchymal stem cells (total volume of 50 μL) (Group 2-CrushCell); Group 3, axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane covered with a monolayer of non-differentiated human mesenchymal stem cells (Group 3-CrushChitIIICell) and Group 4, axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane (Group 4-CrushChitIII). Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index, static sciatic index, extensor postural thrust, and withdrawal reflex latency. Stereological analysis was carried out on regenerated nerve fibers. Results showed that infiltration of human mesenchymal stem cells, or the combination of chitosan membrane enwrapment and human mesenchymal stem cell enrichment after nerve crush injury provide a slight advantage to post-traumatic nerve regeneration. Results obtained with chitosan type III membrane alone confirmed that they significantly improve post-traumatic axonal regrowth and may represent a very promising clinical tool in peripheral nerve reconstructive surgery. Yet, umbilical cord human mesenchymal stem cells, that can be expanded in culture and induced to form several different types of cells, may prove, in future experiments, to be a new source of cells for cell therapy, including targets such as peripheral nerve and muscle.

Doutoramento em Ciências Veterinárias Phd programmes in Veterinary Sciences