Dissection of the early steps in the assembly of the 20S proteasome in Saccharomyces cerevisiae

Tese de dout., Bioquímica (Biologia Celular e Molecular), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2010

Parâmetros de qualidade para a aguardente de medronho

A Aguardente de Medronho, apesar de merecer interesse por parte da Comunidade Europeia desde 1989 (Regulamento (CEE) 1576/89 do conselho de 29 de Maio de 1989, substituído pelo Regulamento (CE) Nº 110/2008 do Parlamento Europeu e do conselho de 15 de Janeiro de 2008), não teve legislação específica até o ano 2000, o que levava a que facilmente se pudessem vender diversas bebidas espirituosas com a designação de Aguardente de Medronho. A legislação só por si não impede falsificações mas limita o campo das falsificações. Também não conduz a que se produzam aguardentes de boa qualidade, até porque os limites fixados para muitos dos compostos são muito altos para produtos de qualidade. Neste campo de optimizar a qualidade dos destilados há ainda muito por fazer mas sem dúvida a actual lei foi o primeiro passo para moralizar o comércio deste destilado, há que lutar por legislação mais apertada para aguardentes de qualidade.

Coreference resolution for portuguese using parallel corpora word alignment

A área de Extração da Informação tem como objetivo essencial investigar métodos e técnicas para transformar a informação não estruturada presente em textos de língua natural em dados estruturados. Um importante passo deste processo é a resolução de correferência, tarefa que identifica diferentes sintagmas nominais que se referem a mesma entidade no discurso. A área de estudos sobre resolução de correferência tem sido extensivamente pesquisada para a Língua Inglesa (Ng, 2010) lista uma série de estudos da área, entretanto tem recebido menos atenção em outras línguas. Isso se deve ao fato de que a grande maioria das abordagens utilizadas nessas pesquisas são baseadas em aprendizado de máquina e, portanto, requerem uma extensa quantidade de dados anotados.

Citocromo P450 2D6: variabilidade na terapêutica e na predisposição para patologias

O Citocromo P450 2D6 (CYP 2D6) é uma importante enzima metabolizadora de fármacos. Apesar de representar apenas 2% do total das isoenzimas CYP, o CYP 2D6 tem um papel importante pois é responsável pela metabolização de cerca de 20 a 25% dos fármacos mais frequentemente utilizados. (Ramamoorthy, 2010) É sabido que nem todos os indivíduos respondem da mesma maneira a um fármaco, podendo alguns sofrer reação adversa devido à toma deste e outros nem apresentar qualquer efeito terapêutico. Tais diferenças na resposta terapêutica devem-se a variações genómicas interindividuais, nos genes que codificam as enzimas responsáveis pelo metabolismo do fármaco. Os alelos polimórficos podem levar a uma redução ou aumento na capacidade metabólica, ao passo que um aumento do número de cópias do gene CYP 2D6 pode conduzir a um aumento da atividade metabólica. Os indivíduos comportam-se de acordo com o seu fenótipo, como metabolizadores lentos, rápidos ou ultra-rápidos (Abraham, 2001) Visto existirem grandes alterações nesta enzima metabolizadora de fármacos, é importante perceber quais as situações onde a segurança e a eficácia estão alteradas, pois qualquer terapêutica tem sempre como base o binómio risco/beneficio. Para além do seu papel bem estabelecido na segurança e eficácia terapêutica, estudos mais recentes relatam que o CYP 2D6 desempenha um papel importante no aparecimento de algumas doenças, condicionando a predisposição individual para patologias, de que é exemplo a esclerose sistémica. (Sanjay Harhang & al, 2001) Como desenvolvimento desta monografia pretende-se estudar os efeitos a nível de segurança e eficácia em determinadas situações terapêuticas e ainda avaliar a associação dos polimorfismos no CYP 2D6 com a predisposição individual para patologias.

A proteomic study of the effects of nutrient restriction in utero on postnatal metabolism

It is widely recognized that protein restriction in utero may cause metabolic and endocrine adaptations, which may be of benefit to the neonate on a short-term basis but may cause adverse long-term conditions such as obesity, Type 2 diabetes, metabolic syndrome, hypertension and cardiovascular diseases. Adequate foetal and early post natal nutrient and energy supply is therefore essential for adult animal health, performance and life span. In this project it was investigated the progressive adaptations of the hepatic proteome in male mink offspring exposed to either a low protein (FL) or an adequate protein (FA) diet in utero fed either on a low protein (LP) or on an adequate (AP) diet from weaning until sexual maturity. Specifically, the aim was to determine the metabolic adaptations at selected phases of the animal’s first annual cycle and establish the metabolic priorities occurring during those phases. The three different morphological stages studied during the first year of development included, end of bone growth at 4 months of age, maximal fat accretion at 6 months of age and sexual maturity at 12 months of age. A reference proteome of mink liver coming from these different animal groups were generated using 2D electrophoresis coupled to MALDI-TOF analysis and the way in which dietary treatment affect their proteome was established. Approximately 330 proteins were detected in the mink liver proteome. A total of 27 comparisons were carried out between all different animal groups which resulted in 20 differentially expressed proteins. An extensive survey was conducted towards the characterization of these proteins including their subcellular localization, the biological processes in which they are involved and their molecular functions. This characterization allowed the identification of proteins in various processes including the glycolysis and fatty acid metabolism. The detailed analysis of the different dietary treatment animal groups was indicative of differences in metabolism and also to changes associated with development in mink.

Rastreamento de jogadores de futebol tendo em vista a análise de modelos de jogo

As atuais exigências do elevado nível de rendimento, num jogo de futebol, tornam imperativo o recurso a novas tecnologias de observação e análise. Nesta dissertação é apresentada uma aplicação, com o objetivo de recolher todas as informações necessárias do vídeo, para efetuar a análise do modelo de jogo de ambas as equipas, em que a análise não faz parte deste trabalho. Disponibilizando ao treinador toda a informação específica sobre o desempenho da equipa e do modelo de jogo usado. A aplicação foi desenvolvida levando em consideração as rotações e inclinações que poderiam afetar as câmaras aquando da aquisição das imagens (vídeos), e também que na maioria das situações apenas parte do campo estaria visível, assim como poderiam existir ampliações. A aplicação é constituída por cinco grandes passos: (a) Deteção da zona do recinto de jogo, baseada na segmentação pela cor, usando para tal uma restrição ao espaço de cor HSV, remoção de regiões insignificantes exteriores ao recinto de jogo e a correção da zona limite deste pelos seus contornos. A segmentação dos jogadores (b), tendo por base o sub-efeito do passo anterior, a existência de buracos no campo na posição dos jogadores, e seu refinamento pela aplicação de filtros morfológicos. A atribuição do jogador a um número e equipa (c), baseada no espaço delimitado pelo jogador, média da cor em HSV deste e restrições da equipa. O rastreamento do jogador (d), baseado em simples fatores de posicionamento e por fim (e) análise do jogo, baseada no rastreamento do jogador, da relação posicional deste com os restantes jogadores, e sectores da equipa, bem como a sua projeção para um campo “modelo”. Toda a informação do posicionamento dos jogadores no campo “modelo,” está formatada para ser enviado para o Sistema de Informação do projeto Footdata. Complementarmente foi também implementada uma biblioteca de manipulação de vídeo com o intuito de, no futuro, ser integrada com o seguimento dos jogadores e modelos de jogo, de forma a permitir à equipa técnica criar apresentações interativas.

Exploring an uncommon host-parasite interaction to unveil the uniqueness of Perkinsus sp as a model organism

We report the exploration of some unique metabolic pathways in Perkinsus olseni a marine protist parasite, responsible to significant mortalities in mollusks, especially in bivalves all around the world. In Algarve, south of Portugal carpet shell clam Ruditapes decussatus mortalities can reach up to 70%, causing social and economic losses. The objective of studying those unique pathways, is finding new therapeutic strategies capable of controlling/eliminating P. olseni proliferation in clams. In that sense metabolic pathways, were explored, and drugs affecting these cycles were tested for activity. The first step involved the identification of the genes behind those pathways, the reconstitution of the main steps, and molecular characterization of those genes and later on, the identification of possible targets within the genes studied. Metabolic cycles were screened due to the fact of not being present in host or differ in a critical way, such as the following pathways: shikimate, MEP-­‐ isoprenoids, Leloir cycle for chitin production, purine biosynthesis (unique among protists), the de novo synthesis of folates (absent in metazoa) and some unique genes like, the alternative oxidase (a branch of respiratory chain) and the hypoxia sensor HPH. All those pathways were covered and possible chemical inhibition using therapeutic drugs was tested with positive results. The relation between the common host Ruditapes decussatus and P. olseni was also explored in a dimension not possible some years ago. With the accessibility to second generation sequencers and microarray analysis platforms, genes involved in host defense or parasite virulence and resistance to the host were deciphered, allowing aiming to new targets (mechanisms and pathways), offering new possibilities for the control of Perkinsus in close environments. The thousands of genes, generated by this work, sequenced and analyzed from this commercial valuable clam and for Perkinsus olseni will be an important and value tool for the scientific community, allowing a better understanding of host-­‐parasite interactions, promoting the usage of P. olseni as an emerging model for alveolata parasites.

Study of transcripts and reactive oxygen species involved in the defence responses of Quercus suber against Phytophthora cinnamomi

The present work has the merit of exploring an insight into the activation of defence genes of Quercus suber during response to infection by Phytophthora cinnamomi. Thus, cDNA-AFLP methodology was used to identify gene fragments differentially present in the mRNA profiles of host cells of micropropagated Q. suber plantlets roots infected with zoospores of P. cinnamomi at different post challenge time points. Six candidate genes were selected based on their interesting cDNA-AFLP expression patterns and homology to genes known to play a role in defence. These six genes encode a cinnamyl alcohol dehydrogenase 2 (QsCAD2), a protein disulphide isomerase (QsPDI), a CC-NBS-LRR resistance protein (QsRPc), thaumatin-like protein (QsTLP), chitinase (QsCHI) and a 1,3-beta glucanase (QsGLU). The current work has been successful in evaluation of the expression of these genes by qRT-PCR. Data analysis revealed that transcript levels of QsRPc, QsCHI, QsCAD2 and QsPDI increased during the early hours of inoculation, while transcript profiles of thaumatin-like protein showed decreasing. No expression was detected for 1,3-beta-glucanase (QsGLU). Furthermore, the choice of suitable reference genes in any new experimental system is absolutely crucial in qRT-PCR; for this reason in this study and for the first time a set of potential reference genes were analyzed and validated for qRT-PCR normalization in the patho-system Phytophthora-Q. suber. Four candidate reference genes polimerase II (QsRPII), eukaryotic translation initiation factor 5A(QsEIF-5A), b-tubulin (QsTUB) and a medium subunit family protein of Clathrin adaptor complexes (QsCACs) were evaluated to determine the most stable internal references in Q. suber. Analysis of stability of genes was carried out using Genex software. Results indicated all these four potential reference genes assumed stable expression. Data analysis revealed that QsRPII and QsCACs were the two most stable genes, while genes QsTUB and QsEIF-5A were the third and the fourth most stable gene, respectively. In this study, a plasmid-based quantitative PCR method was developed to measure P. cinnamomi colonization during infection process of Q. suber. Plasmid-based detection of P. cinnamomi showed a gradual accumulation of the pathogen DNA in cork oak root tips up to 24 h post infection. The higher increase in P. cinnamomi/plasmid DNA ratio occurred between 18 and 24 h. One of the primary objectives of this research was to study the effect of cinnamomins (elicitins secreted by P. cinnamomin) on inducing defence mechanism against the pathogen, as recent histological and ultra-structural studies showed that P. cinnamomi was restricted to the outer cortex root fragments pre-treated with capsicien and cryptogein, suggesting that elicitins can stimulate plant defence reactions against P. cinnamomi. To complement these studies and to have a clear view of the nature of the interaction, the role of cinnamomins in the production of the oxidative burst [ROS and ROS scavenging enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)] and in the defence responses was evaluated. Cork oak seedlings were pretreated with alpha-cinnamomin and then inoculated with P. cinnamomi mycelia. Results showed a significant higher production of reactive oxygen species (ROS) (H2O2 and O2•-) in elicitin and non-elicitin treated roots in interaction with P. cinnamomi in comparison to the corresponding control. The plant group inoculated with the pathogen after cinnamomin treatment showed an earlier increase in H2O2 production but this was lower as compared with that group inoculated with P. cinnamomi alone. Also, in elicitin pre-treated group generally, a lower level of O2•− production during infection was observed as compared with inoculated roots with P. cinnamomi alone without elicitin treatment. Furthermore, in this study, we evaluated activities of antioxidant enzymes upon challenge with P. cinnamomi, with and without pretreatment with alpha cinnamomin. Results indicated that the activities of defense enzymes POD, SOD and CAT increased after P. cinnamomi inoculation when compared with those in the control group. Also, in the group treated with alpha-cinnamomin followed by P. cinnamomi inoculation, a higher level of enzymatic activities was detected as compared with elicitin non-treated group, which suggest the protective effect of alpha-cinnamomin against the pathogen due to higher elevated levels of defense enzymes POD, SOD and CAT during the infection period. Furthermore, a sensitive qPCR method was applied to measure the pathogen biomass in elicited and non-elicited Q. suber roots challenged with P. cinnamomi to elucidate the effect of cinnamomins on the colonization of P. cinnamomi. Plasmid-based quantification of P. cinnamomi showed a significant decrease in accumulation of the pathogen DNA in cork oak roots after treatment with alpha and beta-cinnamomins which attest the role of cinnamomins in promoting defense responses in cork oak against P. cinnamomi invasion.

Qualidade de vida dos idosos na Rede de Cuidados Continuados Integrados no Algarve

A Qualidade de Vida é um tema cada vez mais importante, na atualidade, face ao envelhecimento da população. Com base na convicção de que se deve promover a Qualidade de Vida até aos últimos dias da vida,delineámos uma investigação quantitativa, de caráter exploratório, descritivo e transversal para conhecer a Qualidade de Vida (QdV) na Rede Nacional de Cuidados Continuados Integrados no Algarve (RNCCI), perceber a sua relação com variáveis sócio-demográficas, clínicas, a saúde, o suporte social, a auto-estima e a depressão. Após revisão bibliográfica sobre os conceitos abordados, selecionámos uma amostra de conveniência composta por 86 idosos internados nas unidades de convalescença, média duração e reabilitação, e longa duração e manutenção da RNCCI do Algarve. Dos resultados obtidos evidenciam-se os seguintes aspectos:  A perceção de saúde influencia a QdV geral e, especificamente, as dimensões Funcionamento sensorial, Participação social e Atividades passadas, presentes e futuras.  A depressão influencia negativamente a QdV geral e as dimensões Funcionamento sensorial, Autonomia, Atividades passadas, presentes e futuras e Participação social.  O Estado de Saúde, componente física, afeta positivamente a QdV geral e as dimensões Funcionamento sensorial e Família/Vida familiar, ao passo que a componente mental afeta positivamente a QdV geral.  A avaliação que os sujeitos fazem da RNCCI, o suporte social e a auto-estima influenciam positivamente a QdV dos idosos.  A tipologia não influencia a QdV nem a auto-estima.  As diferenças entre Qualidade de Vida nas diferentes tipologias da RNCCI são circunscritas, existindo apenas diferenças significativas entre Unidades de Convalescença e Unidades de Longa Duração e Manutenção nas dimensões Família/Vida familiar e Morte e morrer e entre Unidades de Média Duração Reabilitação e Unidades de Longa Duração (ULDM’s) e Manutenção na dimensão Intimidade do WHOQOL-OLD.  A tipologia influencia o Suporte Social geral e, especificamente, as suas componentes Satisfação com amigos, Intimidade e Satisfação com a família.  O grau de dependência nas AVD’s influencia a tipologia de internamento.  Internados nas ULDM’s reportam melhor satisfação com os cuidados prestados nas Unidades de Cuidados Continuados.

Searching biocompounds in marine natural extracts with potential use in tumor prevention and treatment

Cancer is a multistage process characterized by three stages: initiation, promotion and progression; and is one of the major killers worldwide. Oxidative stress acts as initiator in tumorigenesis; chronic inflammation promotes cancer; and apoptosis inactivation is an issue in cancer progression. In this study, it was investigated the antioxidant, antiinflammatory and antitumor properties of hexane, ether, chloroform, methanol and water extracts of five species of halophytes: A. macrostachyum, P. coronopus, J. acutus, C. edulis and A. halimus. Antioxidant activity was assessed by DPPH• and ABTS•+ methods, and the total phenolics content (TPC) was evaluated by the Folin-Ciocalteau method. The anti-inflammatory activity of the extracts was determined by the Griess method, and by evaluating the inhibition of NO production in LPS-stimulated RAW- 264.7 macrophages. The cytotoxic activity of the extracts against HepG2 and THP1 cell lines was estimated by the MTT assay, and the results obtained were further compared with the S17 non-tumor cell line. The induction of apoptosis of J. acutus ether extract was assessed by DAPI staining. The highest antioxidant activities was observed in C. edulis methanol and the J. acutus ether extracts against the DPPH• radical; and J. acutus ether and A. halimus ether extracts against the ABTS•+ radical. The methanol extracts of C. edulis and P. coronopus, and the ether extract of J. acutus revealed a high TPC. Generally the antioxidant activity had no correlation with the TPC. The A. halimus chloroform and P. coronopus hexane extracts demonstrated ability to reduce NO production in macrophages (> 50%), revealing their anti-inflammatory capacity. The ether extract of J. acutus showed high cytotoxicity against HepG2 cancer cells, with reduced cellular viability even at the lowest concentrations. This outcome was significantly lower than the obtained with the non-tumor cells (S17). This result was complemented by the induction of apoptosis.

Chemical communication in the Mozambique tilapia: a role for amino acids

The Mozambique tilapia (Oreochromis mossambicus) is a maternal mouthbrooding cichlid from the southern Africa. The olfactory sensitivity of the species to 20 amino acids was assessed using the electro-olfactogram (EOG). We estimated whether the olfactory potency of the polar fraction of male urine can be explained by the presence of identified amino acids. In addition, filtrate and amino acid mixture of the urine of Nile tilapia were used to estimate their olfactory potency for O.mossambicus. Finally, concentrations of the main amino acids were measured in the urine of males of different social status and the correlations between amino acid concentration and hierarchical status were explored. L-cysteine, L-glutamine and L-threonine were the most potent stimuli at M while L-proline and L-aspartate were the least potent. Four groups of amino acids were identified according to their thresholds of detection and three groups – according to the similarity of their ɣ-factors. The estimated threshold of detection for O.mossambicus mixture was higher than that for the filtrate. On the contrary, the threshold of detection for the mixture of Nile tilapia was lower than that for the filtrate The concentration of L-arginine in the urine was positively correlated with fish dominance index. Both L-arginine and L-glutamic acid concentrations had much greater variability in dominant males (DI˃0.5) than in subordinate males (DI˂0.5). The urinary concentrations of L-phenylalanine had similar variability in dominant and subordinate groups. The Mozambique tilapia has olfactory sensitivity to all twenty amino acids tested. The fish showed more acute sensitivity to conspecific urine filtrate than to the heterospecific. Olfactory potency of O.mossambicus filtrate can be largely but not fully explained by the presence of L-arginine, L-glutamic acid and L-phenylalanine. Larginine and L-glutamic acid may indicate the dominance status of the fish and, possibly, individual identity.

Development of a Piggybac based direct reprogramming system for derivation of integration free induced pluripotent stem cells

Induced pluripotent stem cells (iPSc) have great potential for applications in regenerative medicine, disease modeling and basic research. Several methods have been developed for their derivation. The original method of Takahashi and Yamanaka involved the use of retroviral vectors which result in insertional mutagenesis, presence in the genome of potential oncogenes and effects of residual transgene expression on differentiation bias of each particular iPSc line. Other methods have been developed, using different viral vectors (adenovirus and Sendai virus), transient plasmid transfection, mRNA transduction, protein transduction and use of small molecules. However, these methods suffer from low efficiencies; can be extremely labor intensive, or both. An additional method makes use of the piggybac transposon, which has the advantage of inserting its payload into the host genome and being perfectly excised upon re-expression of the transposon transposase. Briefly, a policistronic cassette expressing Oct4, Sox2, Klf4 and C-Myc flanked by piggybac terminal repeats is delivered to the cells along with a plasmid transiently expressing piggybac transposase. Once reprogramming occurs, the cells are re-transfected with transposase and subclones free of tranposon integrations screened for. The procedure is therefore very labor intensive, requiring multiple manipulations and successive rounds of cloning and screening. The original method for reprogramming with the the PiggyBac transposon was created by Woltjen et al in 2009 (schematized here) and describes a process with which it is possible to obtain insert-free iPSc. Insert-free iPSc enables the establishment of better cellular models of iPS and adds a new level of security to the use of these cells in regenerative medicine. Due to the fact that it was based on several low efficiency steps, the overall efficiency of the method is very low (<1%). Moreover, the stochastic transfection, integration, excision and the inexistence of an active way of selection leaves this method in need of extensive characterization and screening of the final clones. In this work we aime to develop a non-integrative iPSc derivation system in which integration and excision of the transgenes can be controlled by simple media manipulations, avoiding labor intensive and potentially mutagenic procedures. To reach our goal we developed a two vector system which is simultaneously delivered to original population of fibroblasts. The first vector, Remo I, carries the reprogramming cassette and GFP under the regulation of a constitutive promoter (CAG). The second vector, Eneas, carries the piggybac transposase associated with an estrogen receptor fragment (ERT2), regulated in a TET-OFF fashion, and its equivalent reverse trans-activator associated with a positive-negative selection cassette under a constitutive promoter. We tested its functionality in HEK 293T cells. The protocol is divided in two the following steps: 1) Obtaining acceptable transfection efficiency into human fibroblasts. 2) Testing the functionality of the construct 3) Determining the ideal concentration of DOX for repressing mPB-ERT2 expression 4) Determining the ideal concentration of TM for transposition into the genome 5) Determining the ideal Windows of no DOX/TM pulse for transposition into the genome 6) 3, 4 and 5) for transposition out of the genome 7) Determination of the ideal concentration of GCV for negative selection We successfully demonstrated that ENEAS behaved as expected in terms of DOX regulation of the expression of mPB-ERT2. We also demonstrated that by delivering the plasmid into 293T HEK cells and manipulating the levels of DOX and TM in the medium, we could obtain puromycin resistant lines. The number of puromycin resistant colonies obtained was significantly higher when DOX as absent, suggesting that the colonies resulted from transposition events. Presence of TM added an extra layer of regulation, albeit weaker. Our PCR analysis, while not a clean as would be desired, suggested that transposition was indeed occurring, although a background level of random integration could not be ruled out. Finally, our attempt to determine whether we could use GVC to select clones that had successfully mobilized PB out of the genome was unsuccessful. Unexpectedly, 293T HEK cells that had been transfected with ENEAS and selected for puromycin resistance were insensitive to GCV.

Synthesis and evaluation of polymer nanoparticles for delivery in RPE cells

Ocular pathologies are among the most debilitating medical conditions affecting all segments of the population. Traditional treatment options are often ineffective, and gene therapy has the potential to become an alternative approach for the treatment of several pathologies. Methacrylate polymers have been described as highly biocompatible and are successfully used in medical applications. Due to their cationic nature, these polymers can be used to form polyplexes with DNA for its delivery. This work aims to study the potential of PDMAEMA (poly(2-(N,N’-dimethylamino)ethyl methacrylate)) as a non viral gene delivery system to the retina. The first part of this work aimed to study the potential for gene delivery of a previously synthesized PDMAEMA polymer of high molecular weight (354kDa). In the second part, we synthesized by RAFT a PDMAEMA with a lower molecular weight (103.3kDa) and similarly, evaluated its ability to act as a gene delivery vehicle. PDMAEMA/DNA polyplexes were prepared at 5, 7.5, 10, 12.5 and 20 nitrogen/phosphorous (N/P) ratio for the 354kDa PDMAEMA and at 5 and 7.5 for the 103.3kDa PDMAEMA. Dynamic light scattering and zeta potential measurements confirmed the nanosize and positive charge of polyplexes for all ratios and for both polymers. Both high and low Mw PDMAEMA were able to efficiently complex and protect DNA from DNase I degradation. Their cytotoxicity was evaluated using a non-retinal cell line (HEK293) and a retinal pigment epithelium (RPE) cell line (D407). We have found that cytotoxicity of the free polymer is concentration and time dependent, as expected, and negligible for all the concentrations of the PDMAEMA-DNA polyplexes. Furthermore, for the concentrations to be used in vivo, the 354kDa PDMAEMA showed no signs of inflammation upon injection in the intravitreal space of C57BL/6 mice. The transfection efficiency, as evaluated by fluorescence microscopy and flow cytometry, showed that the D407 retinal cells were transfected by polyplexes of both high and low Mw PDMAEMA, but with varied efficiency, which was dependent on the N/P ratio. Althogether, these results suggest that PDMAEMA is a feasible candidate for non-viral gene delivery to the retina, and this work constitutes the basis of further studies to elucidate the bottleneck in transfection and further optimization of the material.

Inibição da angiogénese em tumores sólidos: aplicação dos lipossomas catiónicos

Este trabalho pretende abordar a aplicabilidade dos lipossomas catiónicos como veículos de terapia anti-angiogénica, bem como verificar o seu efeito em diversos tipos de cancro. O termo angiogénese define-se como o processo de formação de novos vasos a partir de uma vasculatura pré-existente. Este processo é regulado por várias vias de transdução de sinal que envolvem múltiplos fatores como, por exemplo, o VEGF, o mais potente indutor angiogénico conhecido. A angiogénese é essencial para o crescimento tumoral, pois permite um maior aporte de nutrientes e oxigénio para as células hipóxicas do interior do tumor, que se traduz num aumento da proliferação celular. Nos últimos anos, surgiu um grande interesse na capacidade dos lipossomas catiónicos em reconhecer seletivamente as células endoteliais da vasculatura tumoral. A modificação dos constituintes dos lipossomas catiónicos, como por exemplo a inclusão de polietilenoglicol, permite ultrapassar as principais desvantagens da utilização deste tipo de formulações, como a toxicidade e a rápida eliminação do organismo. A utilização de lipossomas catiónicos na veiculação de terapia anti-angiogénica permite uma maior acumulação dos fármacos nas células-alvo, não só aumentando a eficácia terapêutica como reduzindo a toxicidade associada. Esta estratégia poderá revelar-se um enorme passo na terapia contra o cancro, não só na inibição da progressão tumoral como também, em combinação com a quimioterapia convencional, no aumento das taxas de cura.

Papel das proteínas de choque térmico na apoptose mediada por espécies reativas de oxigénio em culturas celulares

Dissertação de mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015