The pathophysiology of traumatic brain injury (TBI) includes perturbations to energy metabolism. Improving our understanding of cerebral energy metabolism will lead to strategies that improve clinical outcomes. For the studies in my thesis I used microdialysis to deliver carbon-13 labelled substrates to the human brain. I combined this with nuclear magnetic resonance (NMR) spectroscopy of interstitial fluid sampled from the brain to interrogate glucose, lactate and tricarboxylic acid (TCA) cycle metabolism. Study I: I defined the optimal parameters for quantitative proton and carbon-13 NMR of cerebral microdialysates. Study II: I measured baseline microdialysate metabolite concentrations for brain and muscle and investigated the influence of muscle activity and cerebral catheter placement in grey or white matter on metabolite concentrations. Study III: I used 1,2-13C2 glucose to measure glycolysis and pentose phosphate pathway activity. Glycolysis is the dominant lactate-producing pathway but the pentose phosphate pathway also contributes and is increased in some TBI patients. Study IV: I used arterio-venous gradients to measure glucose and lactate delivery to the brain. There are periods after injury when lactate is imported from the circulation despite relatively high brain lactate levels suggesting up-regulation of lactate transport. Study V: I followed the metabolism of 3-13C lactate and demonstrated that lactate is metabolised by the TCA cycle. This occurs in both normal and injured brain but not in muscle. Study VI: I used 2,3-13C2 succinate to investigate the role of the TCA cycle in producing metabolites that are exported into the interstitium. The TCA cycle is found to be a source of lactate. Succinate delivered to the brain improves redox and enhances glutamate uptake into cells. The implications of the findings in my thesis on existing knowledge of cerebral metabolism are discussed. Strategies that might potentiate cerebral metabolism and improve clinical outcomes are suggested.

Eletrólitos poliméricos formados à partir de PIE e um sal de metal alcalino (LiBF4, LiClO4, LiCF3SO3) tem despertado grande interesse devido ao enorme potencial de aplicação em dispositivos eletroquímicos. Nestes sistemas sólidos, a macromolécula atua como solvente para o sal que fica parcialmente dissociado na matriz polimérica originando a condutividade iônica. Na tentativa de se obter complexos cada vez mais condutivos, novos sistemas tem sido propostos. Dentre eles destacam-se a formação das blendas poliméricas. Neste trabalho foram feitas investigações por Ressonância Magnética Nuclear (RMN) para se estudar a dinâmica (iônica e molecular) das blendas [POEx:PEG1-x]8LiBF4 (x=0.75, 0.50 e 0.25). Para isso realizaram-se medidas de largura de linha e taxa de relaxação dos núcleos de 1H e 19F entre - 80°C à + 80°C na freqüência de 36 MHz. Também foram feitas medidas de análise térmica (DSC) e condutividade (?). Em algumas das composições de blendas, os dados extraídos das medidas da taxa de relaxação do 1H, revelaram dinâmicas das cadeias poliméricas do POE e PEG ocorrendo separadamente. Foi observado através da análise das medidas de ressonância do 19F, que os movimentos parecem ocorrer de forma independente aos movimentos segmentários das cadeias. / Polymeric electrolytes made from POE and a alkaline metal salt (LiBF4, LiClO4, LiCF3SO3) have shown great potential in the application of electrochemical devices. In this solid systems, a macromolecule act as solvent for a salt to become partially dissociated in the polymeric matrix originating an ionic conductivity. In the attempt to obtain complexes even more conductive, new systems are proposed. Among these complexes one has distinction, polymeric blends. Investigations have been made by use of Ressonance Magnetic Nuclear (NMR), to study the ionic and molecular dynamics of this blends [POEx:PEG1-x]8LiBF4 (x=0.75, 0.50 e 0.25). For this, measurements of line width and relaxation rates of 1H and 19F in the range of -80°C to + 80°C with frequency of 36 MHz, have been done and also measurements of thermal analyse (DSC) and conductivity (?). For some blend compositions, the relaxation rate of the 1H revel that polymeric chain dynamics of POE and PEG occurs separately. It was seen by the analyse of NMR 19F measurements that the movements of the groups (BF4)- , dissociated by the polymeric matrix, seem to occur independently of the segmentary movements of the chains.

Baseado em uma seqüência já conhecida de Multislice Spin Echo convencional, implementamos uma seqüência do tipo Modified Driven Equilibrium Fourier Transform (MDEFT) adiabática multislice em um sistema de 2T e um de microimagens (9.4T). Essa metodologia utiliza, como pulso de inversão, um pulso de RF com modulação em amplitude e freqüência, conhecido por pulso adiabático. Dessa forma, os tempos de inversão são iguais para todos os planos selecionados, resultando num contraste por T1 uniformemente distribuído ao longo dos mesmos. O uso de um único e longo pulso adiabático de inversão tem, ainda, a vantagem de utilizar uma potência de pico menor para operar da mesma forma que um grupo de m pulsos convencionais. Utilizamos pulsos cujas modulações correspondentes de fase e freqüência foram calculadas com base nas condições de “Offset Independent Adiabaticity” (OIA) e a real eficiência dos mesmos foi avaliada através de simulações e experimentalmente. Para realização dos testes da metodologia desenvolvemos e caracterizamos dois “phantoms”, cujas imagens demonstram a aplicabilidade da metodologia nos dois sistemas utilizados. / Based on the conventional Multislice Spin Echo pulse sequence, we implemented an adiabatic multislice Modified Driven Equilibrium Fourier Transform (MDEFT) pulse sequence on a 2T and a 9.4T microimaging system. This methodology uses, as inversion pulse, an amplitude and frequency modulated RF pulse, known as adiabatic pulse. In that way, the inversion times are the same for all slices, resulting in an evenly distributed T1 contrast. A single and long adiabatic inversion pulse has in addition the advantage of using a reduced peak power to perform in the same way as the group of m conventional pulses. We used pulses whose corresponding phase and frequency modulations were based on Offset Independent Adiabaticity and their real efficiency were evaluated both through simulations and experimentally. To test the methodology, we developed and characterized two phantoms, whose images demonstrate the applicability of the methodology in the two mentioned systems.

Este trabalho foi desenvolvido com o propósito de se obter imagens tomográficas por Ressonância Magnética Nuclear (RMN). Ele foi elaborado em duas partes distintas. Uma delas foi a análise das técnicas de seleção de planos por excitação seletiva, já propostas por outros autores. Para isto desenvolvemos um conjunto de programas computacionais que simulam o comportamento do sistema de spins a partir das soluções da equação de Bloch. A outra foi a adaptação de um espectrômetro de RMN já existente no Laboratório do IFQSC para obtenção de imagens tomográficas. Os resultados mostraram que no protótipo desenvolvido pode-se obter imagens com planos tomográficos de espessura inferior a 1 cm. / This work was developed with the purpose of obtaining Tomoqraphic Images by Nuclear Magnetic Resonance (NMR). It was elaborated in two distinct ways. One of them was the analysis of slice selection by selective excitation, already proposed by other authors. To do this, we developed a package of computer programs that simulates the behavior of a spin system from the Bloch Equation solution. The other was the adaptation of a NMR spectrometer already existing in our laboratory to obtain tomographic imaqes. The results show that our prototype can produce imaqes tomographics slices with width less than 1 cm.

Este trabalho investiga as interações entre o átomo de enxofre e o grupo carbonila nos seguintes compostos: 3-tiaciclopentanona (II), 3-tiaciclohexanona (IV), 4-tiaciclohexanona (V), 3-tiacicloheptanona (VII), 4-tiacicloheptanona(VIII), 5-tiaciclooctanona (X), metiltioacetona (XV), etiltioacetona (XVI), 4-etiltio-2-butanona (XVII), 5-etiltio-2-pentanona(XVIII) e 6-etiltio-2-hexanona (XIX). São apresentados: Revisão bibliográfica sobre interações eletrôinicas intramoleculares. As sínteses dos seguintes compostos: 3-tiaciclohexanona (IV), cicloheptanona (VI), 3-tiacicloheptanona(VII), 4-tiacicloheptanona (VIII), ciclooctanona (IX), 5-tiaciclooctanona (X), 4-etiltio-2-butanona (XVII), 5-etiltio-2-pentanona (XVIII), 6-etiltio-2-hexanona (XIX), 3-oxaciclopentanona(XX), 3-ciclohexenona (XXII) e 9-tiabiciclo(3,3,1)-2-nonanona(XXIII), A 6-etiltio-2-hexanona (XIX), composto ainda não descrito na literatura, foi por nós caracterizado. Os dados de basicidades relativas (Δv) de cetonas cíclicas e aciclicas (I-XXII), pelo emprego do método de ressonância magnética nuclear. Estes dados foram obtidos através de medidas dos deslocamentos das posições dos sinais dos prótons ácidos de fenol e de p-clorofenol associados, em complexo 1:1, com aceptores de prótons, em tetracloreto de carbono. As constantes de equilíbrio (kass) dos complexos doador-aceptor de próton, associados por pontes de hidrogênio, em tetracloreto de carbono. A presente tese permite apresentar as seguintes sugestões e conclusões: A comparação das basicidades da ciclopentanona (I), e tetrahidrotiofeno (XXIV), isoladamente e em mistura, com a basicidade da 3-tiaciclopentanona (II), indica que os valores de Δv e de kass para tiacetonas são medidas de basicidade do oxigênio carbonílico e não do enxofre. As tiacetonas contendo o átomo de enxofre ligado ao carbono α ou β são menos básicas do que as cetonas análogas não substituídas, tanto na série cíclica, como na acíclica. As diminuições de basicidade das tiacetonas cíclicas não são devidas nem ao impedimento estérico para a aproximação do doador de próton e nem, pelo menos exclusivamente, a uma tensão que poderia ser causada pela introdução do átomo de enxofre no anel. As oxacetonas contendo o átomo de oxigênio ligado ao carbono α (XX) e (XXI) são mais básicas do que as tia-análogas (II) e (XV), entretanto, menos básicas do que as cetonas correspondentes não substituídas (I) e (XI). Esta ordem é contraria à esperada dos efeitos indutivos dos dois heteroátomos. Eliminados o impedimento estérico, a tensão do anel e os efeitos indutivos, apresenta-se a possibilidade de uma interação no espaço entre os orbitais n do oxigênio carbonílico e n do enxofre como responsável pela diminuição de basicidade do grupo carbonila, através de considerações de potenciais de ionização e de resultado de correlação entre kass e de σ* de Taft de grupos substituintes. A 5-tiaciclooctanona (X) e a 3-ciclohexenona (XXII) apresentam, em solução de tetracloreto de carbono, aumentos anômalos de basicidade com o aumento da concentração de cetona, quando comparados com as outras cetonas estudadas. A explicação que se poderia fornecer para este comportamento é que ambas as cetonas (X, XXII) existem, em solução, como misturas de conformações, de não interação (menos polar) e de interação (mais polar), sendo que a concentração desta última aumenta com o aumento da concentração de cetona. Os nossos resultados apoiam a hipótese sugerida na literatura da existência,na 5-tiaciclooctanona (X), de uma transferência de carga do enxofre para o grupo carbonila. Semelhantemente, uma transferência de carga da dupla olefínica para o grupo carbonila é por nós proposta para a 3-ciclohexenona (XXII). O nosso método de medida de basicidade relativa mostrou-se útil para a identificação de estruturas com transferência de carga em equilíbrios conformacionais. / This thesis investigates the interactions between the sulphur atom and the carbonyl group in the following compounds: 3-thiacyclopentanone (II), 3-thiacyclohexanone (IV) 4-thiacyclohexanone (V), 3-thiacycloheptanone (VII), 4-thiacycloheptanone (VIII), 5-thiacyclooctanone (X), 4-thiapentan-2-one (XV), 4-thiahexan-2-one (XVI), 5-thiaheptan-2-one (XVII), 6-thiaoctan-2-one (XVIII) and 7-thianonan-2-one (XIX). It contains: A review on the intramolecular electronic interaction described in the literature. The syntheses of the following compounds: 3-thiacyclohexanone (IV), cycloheptanone (VI), 3-thiacycloheptanone (VII), 4-thiacycloheptanone (VIII), cyclooctanone (IX), 5-thiacyclooctanone (X), 5-thiaheptan-2-one (XVII), 6-thiaoctan-2-one (XVIII), 7-thianonan-2-one (XIX), 3-oxacyclopentanone (XX), cyclohex-3-enone (XXII) and 9-thiabicyclo(3,3,1)nonan-2-one (XXIII). The thianonan-2-one (XIX), not yet reported in the literature, was characterized. The data of relative basicities (Δv) for cyclic and open-chain ketones (I-XXII), obtained from the measurements of chemical shifts of hydroxylic proton of phenol and p-chlorophenol associated to the ketones (1:1), in carbon tetrachloride. The equilibrium constants (kas) for the same complexes. The following conclusions and suggestions are presented: The Δv and kas values for thiaketones express the basicity of carbonyl oxygen and not that of the sulphur, as indicated by the comparative basicities measurements for cyclopentanone (I), tetrahydrothiophene (XXIV) and 3-thiacyclopentanone (II). Thiaketones, wich sulphur atom and carbonyl group apart by one or two methylene groups, in cyclic as well as in the open-chain series, show a decrease of basicity in comparison to the corresponding unsubstituted ketones. The decrease of basicity of the cyclic thiaketones cannot be attributed either to the steric hindrance to hydrogen bonding with phenol and p-chlorophenol or to some strain due to the introduction of sulphur atom into the ring. The oxaketones (XX) and (XXI), in which the oxygen atom is separated from the carbonyl group by one methylene group, though of lower basicity than the corresponding unsubstituted ketones, show an increased basicity when compared to the thia-analogues (II) and (XV). The basicity order -CH2-CH2-CO- > -O-CH2-CO- > -S-CH2-CO- is contrary to that expected from the inductive effect of the heteroatoms envolved. Therefore, the inductive effect of sulphur cannot be responsible for the decrease in basicity of the thiaketones. The data of the ionization potentials and the result of the correlation between kas and σ* Taft for the substituents suggest through-space interaction as responsible for the decrease of the carbonyl-group basicity. The 5-thiacyclooctanone (X) and cyclohex-3-enone (XXII) show an abnormal raise of basicity with increased concentration in carbon tetrachloride solution, when compared to the other ketones studied. The existence of a mixture of conformations, the non-interacted (less polar) and interacted (more polar), is proposed to be responsible for these data, as the increase of concentration would lead to an increase of the more polar conformation. Our results give a support to the existence of charge-transfer from sulphur to the carbonyl group in the 5-thiacyclooctanone (X) suggested in the literature.Similarly, a charge-transfer from the πC=C to the πC=O system is now proposed for the cyclohex-3-enone (XXII). Our method of relative basicity measurements show to be useful for the identification of the structures, in which a charge-transfer occurs.

O estudo de soluções iônicas tem grande importância na química analítica. Na RMN, vários pesquisadores se dedicam ao entendimento do papel de íons paramagnéticos nos tempos de relaxação longitudinal (T1) e transversal (T2). A maioria dos trabalhos nesta área se dedicou ao estudo destas influências no T1, que é uma medida bem mais lenta do que a de T2. Assim, neste trabalho se estudou as implicações da relaxometria de T2 por RMN no domínio do tempo (RMN-DT) em soluções de íons paramagnéticos. A partir deste estudo, demonstrou-se a correlação linear entre a taxa de relaxação transversal (1/T2) e a concentração dos íons paramagnéticos. Com isso, usou-se esta metodologia na determinação de constantes do produto de solubilidade (Kps) dos hidróxidos Fe(OH)3, Cu(OH)2 e Mn(OH)2. A determinação da constante de solubilidade (Kps) tem grande importância e aplicação em química, principalmente na separação de íons por precipitação. Foi possível determinar com grande precisão o Kps destes hidróxidos utilizando a metodologia proposta, o que é promissor e encorajador para trabalhos futuros. Estudou-se também a eletrodeposição dos íons Fe3+, Cu2+ e Mn2+ in situ com a RMN-DT. A eletrodeposição tem número considerável de aplicações, tanto na pesquisa, quanto na indústria. E a possibilidade de se monitorar a retirada de íons metálicos sem que esta tenha de ser parada e, além disto, não precisando controlar a viscosidade da solução ou adicionar indicadores químicos é muito interessante. Para este estudo in situ, foram construídas e testadas duas células eletroquímicas, realizadas voltametrias cíclicas para estudo prévio e, finalmente, a eletrodeposição in situ da das soluções. O melhor resultado obtido foi para o Fe3+, seguido do Cu2+, não sendo possível observar a eletrodeposição do Mn2+. / The study of ionic solutions is of great importance to analytical chemistry. In NMR, a significant number of researchers devote themselves to the understanding of the role that paramagnetic ions have on longitudinal (T1) and transverse (T2) relaxation times. However, most of the papers published until today have studied this influences on T1, which is whatsoever more complicated to measure than T2. Therefore, we applied we applied the time domain NMR (TD-NMR) transverse relaxometry to study paramagnetic ions in aqueous solutions. The first application was the determination of the Fe(OH)3, Cu(OH)2 and Mn(OH)2 solubility product constants (Ksp). The knowledge of these constants is of industrial and academic interest. Moreover, Ksp is studied as a direct consequence of chemical equilibrium, which prejudices the acquisition of a deeper understanding to the problematic. Thus, use of TD-NMR to study Ksp is a new approach to the already done, with great teaching potential. It was possible to almost precisely determine the Ksp hydroxide values through the proposed methodology, which is promising and encouraging to future studies. It was also explored Fe3+, Cu2+ and Mn2+ electrochemical-NMR in situ experiments. Electrodeposition has a considerable number of applications in research as in industry. And the possibility to monitor the withdrawn of paramagnetic ions from the solution without ceasing the reaction and without the worry of solution viscosity or the need to add chemical indicator is really interesting. To the in situ study two electrochemical cells were built and tested, cyclic voltammetry and amperometric deposition were made. The best result was for iron, followed by copper. Manganese electrodeposition wasn\'t observed.

The deposition of amyloid in the central nervous system is associated with prevalent neurological disorders such as Alzheimer's and Parkinson's disease. This thesis studies the mechanisms and prevention of amyloid formation in vitro. We specifically focus on Parkinson's disease associated α-synuclein (α-syn). Using novel labeling methods we introduce NMR observable labels onto lysosomal protein glucocerebrosidase (GCase), a leading cause of Parkinson's disease. By introducing NMR active labels we are able to study GCase dynamics and screen potential drug therapeutics (chapter 3). Furthermore, we analyze the three way interaction between GCase, α-syn and lipids. We conclude that GCase is able to effectively chaperone α-syn under lysosomal conditions, both preventing amyloidogenesis and destabilizing mature amyloid fibrils (chapter 4). Additionally, a model chaperone-aggregate system is investigated to gain insight into the mechanisms of small heat shock protein chaperoning, and how such mechanisms prevent aggregation (chapter 5). Finally, a high resolution crystal structure of RNA editing enzyme Cid1 is presented, whilst not directly linked to aggregation, many of the techniques used in this thesis were first developed on Cid1 (chapter 7). Together, we utilize NMR, X-ray crystallography, electron microscopy and native mass spectrometry to elucidate aspects of protein aggregation mechanisms and prevention.

Ce travail porte sur la conception de nouveaux systèmes luminescents à partir de complexes hexanucléaires de terres rares et l'étude de leurs propriétés physico-chimiques. Ces complexes de formule chimique [Ln6(μ6-O)(μ3-OH)8(NO3)6(H2O)n](NO3)2.mH2O avec 0 n 14 et 0 m 6 pour Ln = Pr-Lu, Y peuvent être synthétisés et isolés par hydrolyse contrôlée de sels de terres rares. Ces complexes sont structuralement caractérisés : les ions terres rares occupent les sommets d'un octaèdre moléculaire d'une dizaine d'angströms de diamètre. Ils présentent un intérêt en tant que précurseurs moléculaires. Les complexes hétéro-hexanucléaires, associant plusieurs terres rares, affichent potentiellement des interactions de forte amplitude en termes de luminescence. L’ordre local de ces complexes a été étudié notamment par RMN du noyau 89Y à l’état solide et en solution. Ces complexes ne montrent pas de ségrégation macroscopique, et sont des solutions solides où les terres rares sont statiquement et aléatoirement réparties sur les sommets de chaque entité moléculaire. Ces interactions ont été exploitées afin d’optimiser les propriétés inédites de luminescence d’un polymère de coordination à base d’entités hexanucléaires. Ces propriétés sont modulables en fonction de la sélection des précurseurs. Ces complexes présentent une affinité particulière pour les solvants de type polyol, notamment l’éthylène glycol. En solution, les entités moléculaires se regroupent par le biais de ponts glycol et forment des nano-agrégats. Enfin, cette affinité particulière pour les polyols, nous a poussé à étudier les propriétés de luminescence en solution lorsque les complexes sont fonctionnalisés par des dérivés aromatiques du glycol. / This work focuses on the design of new luminescent systems built from rare earth based-hexanuclear complexes and on the study of their properties. These complexes of general formula [Ln6(μ6-O)(μ3-OH)8(NO3)6(H2O)n](NO3)2.mH2O with 0 n 14 and 0 m 6 when Ln = Pr-Lu, Y can be synthesized and isolated by controlled hydrolysis of rare earth salts. These complexes are structurally characterized: metal cations are located at each vertex of the molecular octahedron, whose diameter is around 10 . They are of interest as molecular precursors. Hetero-hexanuclear complexes, involving several rare earth ions, potentially exhibit efficient interactions in terms of luminescence. Local order of these complexes was investigated on the basis of NMR spectroscopy with 89Y nucleus at solid and solution state. No macroscopic segregation is observed, heterohexanuclear complexes are solid solution compounds where rare earth ions are randomly and statistically dispersed over the vertices of each molecular entities. Interactions in terms of luminescence have been exploited in order to optimize the rare optical properties of a coordination polymer built from hexanuclear entities. The luminescent properties can be modulated depending on the selection of the starting precursors. Hexanuclear complexes have a particular affinity for polyol solvents, especially ethylene glycol. In solution, molecular entities are bridged together to form nano-agregates. Finally, this particular affinity for polyol, prompted us to investigate luminescence properties of aromatic glycol derivatives functionalized complexes.

Abstract The present thesis describes the development of a novel method, referred to as xenon porometry, for the determination of the structural properties of porous materials by means of xenon NMR spectroscopy. The method exploits the high sensitivity of the chemical shift of the ¹²⁹Xe isotope to its local environment. The purpose of the medium added to the sample is to slow down the diffusion of xenon so that the NMR signal of a xenon atom is characteristic of the properties of one pore, and the signals of all the atoms in the sample represent the distribution of the properties. Two types of porous materials (controlled pore glasses and silica gels) with well-known properties and three different media (acetonitrile, cyclohexane, and naphthalene) were used in the studies. The behavior of the medium and dissolved xenon at different temperatures around the melting point of the medium was explained. By varying the pore size of the material, three different correlations that make it possible to measure the pore sizes of unknown materials were experimentally determined. The chemical shift of xenon inside pockets built up in the pores during solidification of the medium turned out to be especially sensitive to pore size, and this correlation makes it possible to determine the pore size distribution. The curious behavior of the chemical shift as a function of pore size was explained by using a model based on the fast exchange between xenon adsorbed on the walls of the pockets and free xenon in the middle of the pockets. It was also proved that the porosity of the materials can be determined by comparing the intensities of two signals originating from xenon dissolved in a liquid medium. A comparison of the xenon porometry method with other methods used for pore size characterization leads to the following conclusions: The range of applications of the method is relatively wide, the measurements are fast and easy to do, the analysis of the spectra is simple on the basis of the information presented in this thesis, and the properties of the materials can be extracted from the spectral data with basic mathematical conversions. Because there are several different types of correlations available in the same spectra that represent the properties of the porous material, the complementary information of all the correlations make it possible to obtain a picture of the structures of very complex systems.

No description available.