The impact of fitness instructor quality on customer satisfaction in fitness centres

XIII Ibero-American Congress on Sport Economics held in the city of Valencia on June 7, 8 and 9, 202

Protein conformational plasticity and aggregation : transthyretin and δ-toxin as two case studies

Tese de doutoramento em Química (Química Biológica), apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraOs organismos vivos possuem atributos comuns que os distinguem do mundo inorgânico. Uma rede complexa de interacções entre moléculas orgânicas propicia a existência e a perpetuação da vida. As proteínas são uma das mais extraordinárias classes de biomoléculas, participando activamente em todos os processos biológicos. Esta ubiquidade das proteínas deve-se à sua relativa plasticidade conformacional, um requisito importante nas reacções bioquímicas, processos dinâmicos por definição. A maioria das proteínas tem uma estrutura tridimensional bem definida, essencial para a sua função biológica. Muitas das doenças hoje conhecidas têm a sua origem num incorrecto funcionamento das proteínas. O estudo da relação existente entre a estrutura de uma dada biomolécula e a sua dinâmica, é um dos tópicos mais importantes na compreensão dos mecanismos moleculares de múltiplas patologias. Relativamente a esta temática, duas proteínas foram o sujeito de estudo na elaboração desta tese. Foram utilizadas técnicas experimentais bem como protocolos computacionais, onde diferentes aspectos biofísicos foram abordados. A bactéria Staphylococcus aureus é responsável por inúmeros casos de septicémia. Umas das toxinas excretadas pela bactéria para o plasma, a d-toxina, é responsável pela desintegração membranar em organismos eucarióticos. Durante o mecanismo infeccioso, o peptídeo experiencia a influência de diferentes ambientes químicos, e por conseguinte com impacto na sua conformação tridimensional. A estrutura anfipática helical do peptídeo foi estudada por ressonância magnética nuclear (NMR). Simulações moleculares foram também produzidas no estudo da plasticidade conformacional e propensão à agregação do peptídeo em solução. A interacção do peptídeo com membranas foi também estudado por dinâmica molecular. Os resultados evidenciam que o estado de agregação do peptídeo pode ser relevante para o processo lítico. A transtirretina (TTR) humana é uma das muitas proteínas envolvidas em doenças amilóides. Dependendo da amiloidogeneceidade da variante proteica, a estabilidade do complexo tetramérico nativo é alterado, ocorrendo dissociação e formação de espécies monoméricas com tendência para agregar. Os agregados solúveis e as fibras amilóides insolúveis são responsáveis pelas alterações morfológicas e morte celular observadas nestas patologias. Um método computacional baseado em acoplagem molecular (“docking”) utilizando dados experimentais foi desenvolvido nesta tese. O objectivo do protocolo centrou-se na modelação molecular de um modelo protofilamentar, a unidade elementar das fibras amilóides. Os modelos polimórficos obtidos foram agrupados de acordo com a sua periodicidade helical, para posterior análise das interfaces proteicas e qualidade estereoquímica das estruturas. Os modelos produzidos poderão ter um impacto significativo em estudos terapêuticos com o objectivo de produzir fármacos que inibam a formação das fibras amilóides.All living organisms possess common attributes that distinguishes them from the surrounding inorganic matter. A complex network of interacting organic molecules are responsible for the existence and perpetual of life. Among the most extraordinary biomolecules are proteins. Proteins are the workhorses of life, they actively participate in all biological processes. This is accomplished through an intrinsic conformational plasticity, a requisite in all biochemical reactions inherently dynamic processes. For most proteins a correct three dimensional structure is essential for its biological function. It is a fact that many diseases can be traced back to malfunction of proteins. Understanding the underlying connection between the biomolecule structure and its dynamics, is thus essential for current day medicine. Throughout this thesis, two proteins were the subject of study using both experimental and computational techniques. Different biophysical aspects were focused stressing the importance of the usage of different approaches to get complementary views. d-lysin is a small peptide excreted by the bacteria Staphylococcus aureus, responsible for the disruption of eukaryotic membranes in infection conditions. On its way to the membrane, the peptide experience subtle chemical environment changes with consequences on peptide conformation. The amphyphatic helical structure of this peptide was studied using nuclear magnetic resonance (NMR), and its conformational plasticity and propensity for aggregation in solution was assessed through molecular dynamics (MD) simulations and NMR. The first stages of the lytic process were also modeled by analyzing MD trajectories describing the interaction of the peptide with a zwiterionic membrane. The results show that peptide aggregation may play a key role in the process. Transthyretin (TTR) is one of the many proteins known to be involved in human amyloid diseases. Depending on the protein variant amyloidogenicity, the native tetrameric complex dissociates into monomeric species with high tendency for aggregation. Soluble aggregates and insoluble amyloid fibrils are responsible for the morphological alterations and cell observed in these pathologies. We developed a computational method using protein docking driven by experimental data, to build a high resolution molecular model of the elementary units that constitute the fibrils. We obtained a polymorphic set of protofilament models, further characterized in terms of helical periodicities and interface match. The overall stereochemical quality of the structures was assessed. This models may be a valuable instrument in the rational design of compounds with therapeutic potential to inhibit amyloid fibril formation.Financial support for the execution and publication of this thesis was provided by Fundação para a Ciência e Tecnologia through grant SFRH/BD/1354/200

The use of biomarkers to evaluate the toxicity of metaldehyde and methiocarb baits to the terrestrial isopod porcellionides pruinosus Brandt, 1833

Biochemical indicators (biomarkers) are known to provide early warning signs of environmental pollution or stress conditions to the organisms, by measuring cellular or molecular responses of the target organism to xenobiotic agents. In this study, the terrestrial isopod Porcellionides pruinosus was exposed to these two molluscicides and three different enzymes, glutathione Stransferase (GST), acetylcholinesterase (AChE) and catalase (CAT) were analyzed to evaluate the effects of the application of the two molluscicides in single exposures and binary mixtures tests. Results indicate that the carbamate methiocarb inhibited significantly AChE activity, but no effects were observed in CAT and GST levels. The exposure to the metaldehyde had no effects on AChE, but a decrease in the higher exposure period was observed in GST levels as well as a general increase in CAT activity. The combined exposure of the two molluscicides resulted in a general decrease in AChE and CAT activity, but no visible effects were observed in terms of GST. The use of several biomarkers was a suitable tool to understand the mode of action of these two molluscicides in this isopod species

Evaluation of the joint effect of glyphosate and dimethoate using a small-scale terrestrial ecosystem

In the present work a small-scale terrestrial ecosystem (STEM) containing a soil collected from an agricultural field in Central Portugal was used to evaluate the effects of the combination of the herbicide glyphosate and the insecticide dimethoate. Earthworms (Eisenia andrei), isopods (Porcellionides pruinosus), turnip seeds (Brassica rapa), and bait-lamina strips were placed in the STEM. The results showed that the application of the recommended field dose of both pesticides did not cause any effect on the weight variation of earthworms and growth of the plants. The application of the herbicide, even at 5 and 10 times the field dose, increased feeding activity in soil (bait-lamina test), although the application of dimethoate led to a decrease in feeding activity in all concentrations tested. The binary mixtures performed showed that according to the Independent Action model, synergism (higher effect than expected from the single exposures) was observed in both the shoot length and fresh weight of B. rapa at 5 times the field dose, but antagonism was observed at 10 times the field dose. Regarding the germination success, synergism was observed at the field dose, but antagonism was detected at 5 times and 10 times the field dose. There was a decrease on the earthworm's weight in all concentrations tested, although no statistical differences were observed in any of the treatments made. Regarding depth distribution of E. andrei, worms were found in the upper layer more than it was predicted for all concentrations. In the mixtures with the field and 5 times the field dose there was a decrease in the feeding activity (bait-lamina consumption) by the soil fauna. From the four biomarkers assessed on the isopods (Catalase, Acetylcholinesterase, Glutathione-S-transferase, and Lipid peroxidation), only a significant decrease in the Acetylcholinesterase activity upon dimethoate and the binary mixtures exposures performed with the field dose was observed and on Lipid peroxidation at the field doses of single and binary exposures. (C) 2011 Elsevier Inc. All rights reserved

Joint effects of chlorpyrifos and mancozeb to the terrestrial isopod Porcellionides pruinosus: a multiple biomarker approach

The exposure to pesticides by non-target soil biota has long been regarded as a serious downside of modern agriculture regimes and subject of heated debate. Of utmost relevance is the exposure to pesticide mixtures since their effects have shown not to necessarily reflect the individual toxicity of its components and even the simple addition of effects may lead to consequences not clearly anticipated. In this work, a multiple biomarker approach was employed to identify the mechanistic and time-effects underlying several single and mixture treatments of chlorpyrifos and mancozeb in juveniles and adults of the terrestrial isopod Porcellionides pruinosus. The effects of both pesticides and mixture at recommended doses were mostly transitory under these controlled conditions and one-pulse exposure. While imbalances were identified on detoxification and oxidative stress-related enzymes, isopods generally showed the ability to recover until the end of the experiment. Juveniles showed, however, higher vulnerability than adults. The most notorious differences between life stages occurred in energy-related parameters where distinct performances and stress-handling behaviours were observed, suggesting higher metabolic costs in juveniles. Our results stress that understanding the time-dependence of the underlying mechanisms governing the joint-effects of pesticides can help assessing and anticipating mixtures’ effects. Moreover, it is also emphasized the importance taking life stage-related differences in consideration when evaluating the environmental risks of pesticides and pesticide mixtures

projecto interdisciplinar/metodologias integradas

Depois de descrever e fundamentar a concepção do PIMI (Projecto Interdisciplinar/Metodologias integradas), apresenta-se um conjunto de intervenções elaboradas em equipes de 2 a 3 professores da ESELx referentes a projectos realizados nos jardins de infância cooperantes da prática pedagógica ao longo do ano lectivo de 2008/09. Com estas breves apresentações pretende-se cruzar a visão inter/multidisciplinar inerente ao trabalho de projecto com crianças (Katz e Chard, 2009) com os saberes e reflexões específicos das diferentes metodologias relativas às áreas de conteúdo tal como estão expressas nas Orientações Curriculares para a Educação Pré-Escolar (1997/2002). Apresentam-se reflexões a duas ou três mãos sobre projectos específicos que conduzem a uma visão crítica sobre como se constrói a transversalidade e a especificidade no currículo, isto é, como se constrói o conhecimento (Roldão, 2004). Finalmente, apontam-se alguns dados avaliativos do processo e tecem-se desafios finais e implicações para a supervisão da prática profissional do 2º ciclo de formação (Bolonha), à luz do Decreto-Lei nº 47 /2007 de 22 de Fevereiro. O Projecto Interdisciplinar/Metodologias Integradas (PIMI) dos cursos de Formação Inicial de Educadores de Infância da ESELx, na sua concepção original, terminará no ano lectivo de 2009/2010

Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario

The linear stability of Alfvén eigenmodes in the presence of fusion-born alpha particles is thoroughly assessed for two variants of an ITER baseline scenario, which differ significantly in their core and pedestal temperatures. A systematic approach based on CASTOR-K (Borba and Kerner 1999 J. Comput. Phys. 153 101; Nabais et al 2015 Plasma Sci. Technol. 17 89) is used that considers all possible eigenmodes for a given magnetic equilibrium and determines their growth rates due to alpha-particle drive and Landau damping on fuel ions, helium ashes and electrons. It is found that the fastest growing instabilities in the aforementioned ITER scenario are core-localized, low-shear toroidal Alfvén eigenmodes. The largest growth-rates occur in the scenario variant with higher core temperatures, which has the highest alpha-particle density and density gradient, for eigenmodes with toroidal mode numbers . Although these eigenmodes suffer significant radiative damping, which is also evaluated, their growth rates remain larger than those of the most unstable eigenmodes found in the variant of the ITER baseline scenario with lower core temperatures, which have and are not affected by radiative damping

Sensitivity of alpha-particle-driven Alfvén eigenmodes to q-profile variation in ITER scenarios

A perturbative hybrid ideal-MHD/drift-kinetic approach to assess the stability of alpha-particle-driven Alfv�n eigenmodes in burning plasmas is used to show that certain foreseen ITER scenarios, namely the MA baseline scenario with very low and broad core magnetic shear, are sensitive to small changes in the background magnetic equilibrium. Slight variations (of the order of ) of the safety-factor value on axis are seen to cause large changes in the growth rate, toroidal mode number, and radial location of the most unstable eigenmodes found. The observed sensitivity is shown to proceed from the very low magnetic shear values attained throughout the plasma core, raising issues about reliable predictions of alpha-particle transport in burning plasmas