Metabolism of primary astrocytes studied by NMR: metabolic trafficking and neuroprotection

Dissertation presented to obtain a Ph. D. degree in Biochemistry by Universidade Nova de Lisboa, Instituto de Tecnologia Química e Biológica.

Metabolic flux analysis of neural cell metabolism in primary cultures

Dissertation presented to obtain the Ph.D degree in Biochemistry, Neuroscience

Role of the DHH1 Gene in the Regulation of Monocarboxylic Acids Transporters Expression in Saccharomyces cerevisiae

Previous experiments revealed that DHH1, a RNA helicase involved in the regulation of mRNA stability and translation, complemented the phenotype of a Saccharomyces cerevisiae mutant affected in the expression of genes coding for monocarboxylic-acids transporters, JEN1 and ADY2 (Paiva S, Althoff S, Casal M, Leao C. FEMS Microbiol Lett, 1999, 170∶301–306). In wild type cells, JEN1 expression had been shown to be undetectable in the presence of glucose or formic acid, and induced in the presence of lactate. In this work, we show that JEN1 mRNA accumulates in a dhh1 mutant, when formic acid was used as sole carbon source. Dhh1 interacts with the decapping activator Dcp1 and with the deadenylase complex. This led to the hypothesis that JEN1 expression is post-transcriptionally regulated by Dhh1 in formic acid. Analyses of JEN1 mRNAs decay in wild-type and dhh1 mutant strains confirmed this hypothesis. In these conditions, the stabilized JEN1 mRNA was associated to polysomes but no Jen1 protein could be detected, either by measurable lactate carrier activity, Jen1-GFP fluorescence detection or western blots. These results revealed the complexity of the expression regulation of JEN1 in S. cerevisiae and evidenced the importance of DHH1 in this process. Additionally, microarray analyses of dhh1 mutant indicated that Dhh1 plays a large role in metabolic adaptation, suggesting that carbon source changes triggers a complex interplay between transcriptional and post-transcriptional effects.

Does Metabolic Syndrome Predict Significant Angiographic Coronary Artery Disease?

INTRODUCTION: Metabolic syndrome (MS) is an independent predictor of acute cardiovascular events. However, few studies have addressed the relationship between MS and stable angiographic coronary artery disease (CAD), which has a different pathophysiological mechanism. We aimed to study the independent predictors for significant CAD, and to analyze the impact of MS (by the AHA/NHLBI definition) on CAD. METHODS: We prospectively included 300 patients, mean age 64±9 years, 59% male, admitted for elective coronary angiography (suspected ischemic heart disease), excluding patients with known cardiac disease. All patients underwent assessment of demographic, anthropometric, and laboratory data and risk factors, and subsequently underwent coronary angiography. RESULTS: In the study population, 23.0% were diabetic, 40.5% had MS (and no diabetes) and 36.7% had neither diagnosis. Significant CAD was present in 51.3% of patients. CAD patients were older and more frequently male and diabetic, with increased triglycerides and glucose and lower HDL cholesterol. Abdominal obesity was also less prevalent. MS was not associated with the presence of CAD (OR 0.94, 95% CI 0.59-1.48, p=0.778). Of the MS components, the most important predictors of CAD were increased glucose and triglycerides. Abdominal obesity was associated with a lower risk of CAD. In a multivariate logistic regression model for CAD, independent predictors of CAD were age, male gender, glucose and triglycerides. Body mass index had a protective effect. CONCLUSIONS: Although MS is associated with cardiovascular events, the same was not found for stable angiographically proven CAD. Age, gender, diabetes and triglycerides are the most influential factors for CAD, with abdominal obesity as a protective factor.

Prevalence of Metabolic Syndrome and Diabetes on a High-Risk Population with Suspected Coronary Artery Disease

Objectivos: A prevalência de Sindroma Metabólica (SM) e diabetes é variável consoante a definição utilizada, assim como com a região geográfica e o grupo étnico estudado. Não existem estudos em indivíduos portugueses com suspeita de doença arterial coronária. Analisámos a prevalência de SM e diabetes nesta população específica de doentes, comparando também definições. Métodos: Incluíram-se no estudo 300 indivíduos, com uma idade media de 64 ± 9 anos, 59% do género masculino, admitidos para angiografia coronária electiva, tendo sido excluídos os doentes com doença cardíaca previamente conhecida. Avaliou-se a prevalência de SM e de diabetes. Resultados: A prevalência ajustada de SM foi de 39,3% (critério NCEP-ATP III), 53,8% (critério IDF) e 48,4% (critério AHA/NHLBI). A prevalência ajustada de diabetes foi de 14,8% pela definição prévia da ADA e de 36.4% com a definição mais recente. A concordância global entre as definições de SM foi de 45,3%, sendo mais elevada entre as definições da AHA/NHLBI e da NCEP-ATP III (Kappa 0,821). A prevalência de SM está altamente dependente da idade em ambos os géneros, sendo mais prevalente no género feminino. A prevalência de diabetes é também dependente da idade, sendo semelhante em ambos os géneros. O componente de SM mais frequente é a hipertensão arterial, seguido pela obesidade abdominal, elevação da glicose, colesterol-HDL baixo e finalmente elevação dos triglicéridos. É também importante referir que 60% dos doentes estavam sob terapêutica hipolipemiante (56,6% com estatinas, 1,7% com fibratos e 1,7% com ambos). A diferença mais significativa entre géneros no que diz respeito aos componentes de SM é a elevada prevalência de obesidade abdominal no género feminino. Conclusões: Nesta população de alto risco, a prevalência de SM é elevada, sendo contudo a prevalência de diabetes semelhante à registada em estudos epidemiológicos na população geral.

Dynamic stability metrics for the container loading problem

The Container Loading Problem (CLP) literature has traditionally evaluated the dynamic stability of cargo by applying two metrics to box arrangements: the mean number of boxes supporting the items excluding those placed directly on the floor (M1) and the percentage of boxes with insufficient lateral support (M2). However, these metrics, that aim to be proxies for cargo stability during transportation, fail to translate real-world cargo conditions of dynamic stability. In this paper two new performance indicators are proposed to evaluate the dynamic stability of cargo arrangements: the number of fallen boxes (NFB) and the number of boxes within the Damage Boundary Curve fragility test (NB_DBC). Using 1500 solutions for well-known problem instances found in the literature, these new performance indicators are evaluated using a physics simulation tool (StableCargo), replacing the real-world transportation by a truck with a simulation of the dynamic behaviour of container loading arrangements. Two new dynamic stability metrics that can be integrated within any container loading algorithm are also proposed. The metrics are analytical models of the proposed stability performance indicators, computed by multiple linear regression. Pearson’s r correlation coefficient was used as an evaluation parameter for the performance of the models. The extensive computational results show that the proposed metrics are better proxies for dynamic stability in the CLP than the previous widely used metrics.

Full-scale biological phosphorus removal: quantification of storage polymers, microbial performance and metabolic modelling

Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica

Insights into human carboxylesterase 2 stability and activity in vivo and in vitro

Dissertation to obtain a Master Degree in Biotechnology

Yeast as a model system to study genetic and post-translational regulation of metabolic pathways in mammals

Dissertation presented to obtain the Ph.D degree in Biology