Epilepsy is a neurological disorder that presents a significant public health burden, with an estimated five million people being newly diagnosed each year. However, current therapeutics designed to modify neuronal processes, provide no relief to 1-in-3 epileptic patients. Additionally, no disease modifying therapies currently exist to treat the underlying pathological processes involved in epileptogenesis. The overarching goal of this project is to further characterize the role astrocytes play in epileptogenesis, in hopes of revealing novel therapeutic targets to benefit patients who otherwise have no effective treatment options. System xc- (SXC), a cystine/glutamate antiporter expressed in astrocytes, is one such target that has been shown to play a critical role in establishing ambient extracellular glutamate levels in both health and disease. SXC has been shown to play a major role in setting ambient glutamatergic tone in the central nervous system (CNS) as pharmacological inhibition of SXC, using (S)-4-carboxyphenylglycine (S-4-CPG) or antisense xCT, resulted in a 60% reduction in extrasynaptic glutamate in the nucleus accumbens. Additionally, investigations in tumor-associated epilepsy revealed that overexpression of SXC seen in glioblastomas lead to higher levels of peritumoral glutamate, neuronal excitotoxicity, and ultimately seizures. These studies also found that SXC inhibition with sulfasalazine (SAS), an FDA approved drug and potent inhibitor of SXC, can ameliorate seizure burden in a glioblastoma mouse model. Therefore, the principal objective of this study is to further investigate the role of astrocytic SXC activity in epileptogenesis and seizure generation. In doing so, we also evaluated the efficacy of SAS in reducing seizure burden in vivo using an astrogliosis-mediated epilepsy mouse model. In this dissertation we show that (1) SXC inhibition, using SAS, is able to decrease induced epileptiform activity in multiple models of chemically induced hyperexcitability (2) this is due to a preferential decrease of NMDAR-mediated currents and (3) SXC inhibition, via SAS, decreases seizure burden in vivo in an astrogliosis-mediated epilepsy model. / Doctor of Philosophy / Epilepsy, characterized by unpredictable seizures, affects approximately 2.2 million Americans, with 150,000 new cases being diagnosed each year. Seizures typically occur when there is an imbalance between the excitatory and inhibitory processes in the brain. Because neurons are the primary cell in the brain that carry out these processes, clinically used anti-epileptic drugs (AEDs) work by either decreasing neuronal excitation or increasing neuronal inhibition. Despite success with managing seizures, up to 1-in-3 patients with epilepsy do not find any relief with existing AEDs. A statistic that has not changed in over 50 years of drug development. With this in mind, the overarching goal of this dissertation is to explore the efficacy of targeting non-neuronal processes to treat epilepsy and broaden the search for new AED targets by further characterizing a unique mouse model of epilepsy. One such target studied in our lab is system xc- (SXC), a glutamate/cystine antiporter present on astrocytes, a non-neuronal cell that provides maintenance, support and protection for neurons. Investigations in tumor-associated epilepsy from our lab revealed that hyperactivity of SXC in tumor cells was directly related to the development of tumor-associated epilepsy. These studies also revealed that SXC inhibition using sulfasalazine (SAS), an FDA approved drug, can decrease seizure burden in a tumor mouse model. Therefore, the principal objective of this study is to further investigate the role of astrocytic SXC activity in the development of epilepsy and seizure generation. In this dissertation we show that SXC inhibition, using SAS, is able to decrease neuronal hyperactivity and decreases seizure burden in an astrogliosis-mediated epilepsy model.

No description available.

Cancer-induced pain (CIP) is a debilitating condition that accompanies late-stage cancer for the majority of patients. The work presented in this dissertation addresses the multifaceted role of glutamate in cancer cell-induced pain signalling and provides several potential therapeutic directions. Several cell types, including breast cancer cells and microglia, release glutamate via the system xC- antiporter. To limit the excitotoxic tendency of breast cancer cells to release glutamate in excess, we first indirectly inhibited xCT, the active subunit of system xC-, with the TrkA inhibitor AG879. We demonstrated that the system xC- antiporter is functionally influenced by the actions of nerve growth factor on its cognate receptor, TrkA, and that inhibiting this complex reduced CIP via downstream actions on xCT. Co-culture studies then demonstrated the direct effect of glutamate released by wildtype MDA-MB-231 carcinoma cells on microglial activation, as well as functional system xC- activity, while knockdown of xCT in MDA-MB-231 cells mitigated microglial activation and cystine uptake. Blockade of system xC- with sulfasalazine attenuated nociception in an immunocompetent murine model of CIP and inhibited tumour-induced microglial activation in the dorsal horn of the spinal cord. Finally, tumour-induced nociceptive behaviours appeared to progress in parallel with microglial activation in the hippocampus, and ablating microglia delayed the onset and severity of tumour-induced nociceptive behaviours, confirming that microglia are implicated in CIP and regional microglia are influenced by this pain. This is the first experimental evidence to demonstrate the effects of peripheral tumour on hippocampal microglial activation in relation to cancer-related nociception. These data collectively demonstrate that the system xC- antiporter is functionally implicated in CIP and may be particularly relevant to pain progression through spinal microglia. Upregulated xCT in chronically activated microglia may be one pathway to central glutamate cytotoxicity. Therefore, microglial xCT may therefore be a valuable target for mitigating CIP. / Thesis / Doctor of Philosophy (Medical Science) / Cancer-induced pain (CIP) is a debilitating condition that accompanies late-stage metastatic cancer. Clinically, achieving analgesia often comes at the expense of patients’ quality of life, as current therapeutics fail to adequately manage this pain and induce dose-dependent side effects. Cancer cells secrete excess amounts of glutamate, a signalling molecule involved in CIP, which can activate immune cells called microglia within the spinal cord. Mice that demonstrate tumour-induced pain exhibit an amplified immune response that manifests through the activation pattern and quantity of microglia within the spinal cord, as well as brain regions implicated in pain and distress. Pharmacologically blocking glutamate release from cancer cells limits this pain response, in addition to several physiological indicators of pain, including microglial activation in the central nervous system. Changes in microglia-related glutamate signalling may reflect the emotional problems reported by patients with CIP. Better understanding the mechanisms of CIP will help generate more comprehensive treatment approaches.

The pnmary purpose of this dissertation is to define the function of Psalm 90 and its relationship with regard to adjacent psalms. Keeping this purpose in mind, the dissertation is composed of two main parts. The first part deals with textual notes, structural analysis, the date of the psalm and the possible situation it arose from, and then an attempt is made about the function of the psalm. Concerning the structural analysis, this study reveals that the psalm forms a unity in contrast to the views of Muller and Zenger who have argued for the division of the psalm into two parts. The function that the psalm has within itself is to appeal to Yahweh to intervene in the dilemma the psalmist was facing in the exilic or postexilic situation. However, since the psalm itself does not hint at any clue as to what the actual situation for the appeal was, the study is extended to the examination of the canonical perspective with regard to adjacent Psalms 89 and 91. This consists of the second part, and here Psalm 90 is compared to Psalms 89 and 91 in terms of lexical, thematic, and structural aspects. The study of this part shows that Psalm 90 forms close links with the lament section of Psalm 89 (vv. 39-51) as well as Psalm 91, and the conclusion suggests that Psalm 90 should be interpreted in the light of Psalm 89, thus reflecting the destruction of the Davidic dynasty described in Psalm 89. Concerning the relationship between Psalms 90 and 91, the latter serves as an answer to the former in order to persuade the readers that Yahweh 1s a refuge to those who seek security and protection from him. / Old Testament / Th. M.(Old Testament)

The pnmary purpose of this dissertation is to define the function of Psalm 90 and its relationship with regard to adjacent psalms. Keeping this purpose in mind, the dissertation is composed of two main parts. The first part deals with textual notes, structural analysis, the date of the psalm and the possible situation it arose from, and then an attempt is made about the function of the psalm. Concerning the structural analysis, this study reveals that the psalm forms a unity in contrast to the views of Muller and Zenger who have argued for the division of the psalm into two parts. The function that the psalm has within itself is to appeal to Yahweh to intervene in the dilemma the psalmist was facing in the exilic or postexilic situation. However, since the psalm itself does not hint at any clue as to what the actual situation for the appeal was, the study is extended to the examination of the canonical perspective with regard to adjacent Psalms 89 and 91. This consists of the second part, and here Psalm 90 is compared to Psalms 89 and 91 in terms of lexical, thematic, and structural aspects. The study of this part shows that Psalm 90 forms close links with the lament section of Psalm 89 (vv. 39-51) as well as Psalm 91, and the conclusion suggests that Psalm 90 should be interpreted in the light of Psalm 89, thus reflecting the destruction of the Davidic dynasty described in Psalm 89. Concerning the relationship between Psalms 90 and 91, the latter serves as an answer to the former in order to persuade the readers that Yahweh 1s a refuge to those who seek security and protection from him. / Biblical and Ancient Studies / Th. M.(Old Testament)

This dissertation argues that Book IV of the canonical Hebrew Psalter (Pss 90–106) sustains the hope that God will keep his covenant with David by installing a future king from David’s line. Chapter 1 introduces the debate, states the thesis, surveys the history of psalmic interpretation, and summarizes recent canonical views that see David either diminished or sustained in Book IV. Chapter 2 presents an eclectic canonical methodology that honors the five-book division, accounts for superscriptions, incipits, and closings, senses a broad narrative progression, acknowledges psalmic collections, recognizes lexical, thematic, and structural resonance beween psalms, and considers inner-biblical allusions. Chapter 3 explores the covenantal contradiction in Psalm 89 and proposes that Psalm 90 continues and complements the lament in Psalm 89 which questioned the character and reign of God due to the fallen Davidic throne and the severed Davidic line. Chapter 4 analyzes Psalms 90–92 and argues that a reimagined Moses enters Book IV to intercede for Israel (90) in response to the unfulfilled Davidic covenant in Psalm 89. Psalms 90–92 then allude to Deuteronomy 32–33 and progress from pained petition (90) to promised protection (91) to restored rejoicing (92). Chapter 5 explores the message and function of Psalm 101 and argues that its intra-book links, Davidic title, royal voice, lamenting tone, future orientation, inter-psalm allusions, and strategic placement make it a central psalm sustaining Davidic hope in Book IV. Chapter 6 explores the lexical and thematic resonance among Psalms 90, 102, and 103 and argues that the afflicted Davidide in Psalm 102 applies and echoes the plaintive prayer of Moses in Psalm 90 and that the Davidic praise in Psalm 103 answers both Psalms 90 and 102. Thus David is forgiven and restored along with the people in Psalm 103. Chapter 7 concludes by reviewing the evidence from each chapter and proposing that the overall structure and message of Book IV sustains the hope that God will keep his covenant with David.

Pancreatic cancer (PC) is known to be highly resistant to chemotherapy. Transporters, which regulate the influx and efflux of substrates across the plasma membrane, may play a role in PC drug resistance. ABC transporters are a large family of transmembrane proteins with diverse physiological functions, several of which play major roles in cancer drug resistance. Given that 90% of PC express a mutant K-ras oncogene and that PC are highly hypoxic, I postulated that constitutive K-ras activation and/or hypoxia may correlate with ABC transporter expression, which in turn may promote drug resistance in PC. Using normal and PC cell lines either overexpressing mutant K-ras or subjected to hypoxic treatment, mRNA expression was profiled for 48 ABC transporters. My findings indicate that expression of mutant K-ras and hypoxic treatment, as well as long-term exposure to chemotherapy, may contribute to the development of drug resistance in PC cells in part by inducing the expression of ABC transporters. Similar to ABC transporters, I investigated whether amino acid transporters would mediate drug resistance in PC. The xc" amino acid transporter (xc") mediates cellular uptake of cystine for the biosynthesis of glutathione, a major detoxifying agent. Because the xc" has been regulates the growth of various cancer cell types, and x," is expressed in the pancreas, I postulated that the xc" may be involved in growth and drug resistance in PC. The xc" transporter is differentially expressed in normal pancreatic tissues and is overexpressed in PC in vivo. UsingPC cell lines, I found that cystine uptake via the N.: was required for growth and survival in response to oxidative stress, and that expression of the xc" correlated with gemcitabine resistance. Accordingly, inhibition of xc" expression via siRNA reduced PC cell proliferation and restored sensitivity to gemcitabine. I also identified the anti-inflammatory drug sulfasalazine as a mixed inhibitor of the x,-, which acts to inhibit cell proliferation via reducing xc" activity and not by reducing NFKB activity. My findings thus indicate that the xc" plays a role in PC growth in part by contributing to glutathione synthesis to promote PC cell proliferation, survival, and drug resistance.

No description available.

Les transporteurs d’acides aminés sont très souvent surexprimés au niveau des cellules tumorales et représentent une cible moléculaire privilégiée pour l’imagerie TEP (Tomographie par Emission de Positons) des cancers. Dans le but d’accéder à des radiotraceurs spécifiques de ces transporteurs, les travaux de thèse ont consisté à mettre au point - dans une première partie, une nouvelle méthode de marquage au fluor-18 d’acides aminés fluorés basée sur la déoxyradiofluoration de précurseurs hydroxyaminoesters, via un intermédiaire aziridinium, - et dans une seconde partie, le marquage au carbone-11 de la sulfasalazine, un inhibiteur sélectif des transporteurs Xc-. La réaction de déoxyradiofluoration des hydroxyaminoesters de structure sérine, méthylsérine ou hydroxyphénylalanine, facilement accessibles et stables, a permis d’obtenir à température ambiante les [18F]fluoroaminoesters correspondants avec efficacité et reproductibilité. La régiosélectivité de la réaction a été trouvée dépendante des substituants du cycle aziridinium et de la fonction amine. La radiosynthèse de la [11C]-sulfasalazine a été réalisée avec succès par couplage d’un sel de diazonium approprié avec l’acide [11C]salicylique obtenu par réaction de [11C]carboxylation d’un précurseur bismagnésien issu du iodophénol. L’automatisation de cette radiosynthèse est en cours d’optimisation afin de produire la [11C]sulfasalazine en quantité suffisante pour réaliser les études in vivo. / Aminoacid transporters are often overexpressed in tumour cells and they represent molecular targets of choice for cancer imaging by Positron Emission Tomography (PET). In order to access to specific radiotracers of these transporters, the thesis project aimed at developing – in a first part, a new 18F-radiolabeling method of fluoroaminoacids based on deoxyradiofluorination of hydroxyaminoester precursors via an aziridinium intermediate – and in a second part, the radiolabelling with carbon-11 of sulfasalazine, an selective inhibiter of Xc- transporters. Deoxyradiofluorination reaction of stable and easily accessible hydroxyaminoesters possessing a serine, methylserine or hydroxyphenylalanine moiety, led to [18F]fluoroaminoesters at room temperature in high and reproducible radiochemical yields. Regioselectivity was function of the substituents on aziridinium ring and amine function. The radiosynthesis of [11C]sulfasalazine has been successfully achieved by coupling reaction of an appropriate diazonium salt with [11C]salicylic acid, obtained by [11C]carboxylation of a bismagnesium precursor from iodophenol. The automation of the radiosynthesis is in progress to produce [11C]sulfasalazine for in vivo studies.

Made available in DSpace on 2016-08-19T12:56:37Z (GMT). No. of bitstreams: 1 Dissertacao Andre.pdf: 2646720 bytes, checksum: 5239249ae6d8f92c287772beaafd5621 (MD5) Previous issue date: 2011-09-19 / This work presents a comparative study of Black Pearls 2000 (BP) and Vulcan XC-72R (obtained concerning the oxidation of ethanol, the nanomaterial Ni(II)(PAN)2/(VC) presented higher values of current than the Ni(II)(PAN)2/(BP). A heat treatment study was carried out for the nanocomposite Ni(II)(PAN)2/(VC) because this material has shown the highest current densities for ethanol oxidation. This material was heat treated (500, 600 and 700 °C), characterized and tested for electrochemical oxidation of ethanol, and compared with the nanocomposite prepared at 25 °C. The heat treatment showed significant influence on properties such as morphology, particle size of both the support and the metal structure, and electrocatalytic activity. The nanocomposite treated at 500 °C showed better performance for electrocatalytic oxidation of ethanol (VC) nanomateriais, used as support for the complex Ni(II)(PAN)2. The composites synthesized were characterized by the following techniques: Transmission Electron Microscopy (TEM), X-ray diffraction and Cyclic Voltammetry. The results showed that the carbon support Vulcan XC-72R, is more porous than the Black Pearls 2000 and both have approximately, the same average particle size. Voltammetric analysis showed that the nanocomposite Ni(II)(PAN)2 presented lower separation between the anodic and cathodic peak potential (ΔEp) , for the pair Ni2+ / Ni3+, than the Ni(II)(PAN)2, however Ni(II)(PAN)2 presented less current density, for this redox couple. The electrocatalytical activity of the two nanocomposites through ethanol oxidation was evaluated by the techniques cyclic voltammetry and chronoamperometry. For the cyclic voltammetric study, Ni(II)(PAN)2/(BP) presented a maximum oxidation for the ethanol at 0.5 V while Ni(II)(PAN)2/(VC) showed a maximum oxidation at 0.6 V, in sodium hydroxide solution 1 mol L-1 with a concentration of 0.137 mol L-1 ethanol. Considering the current densities. / O presente trabalho mostra o estudo comparativo entre nanomateriais de carbono Black Pearls 2000 (BP) e Vulcan XC-72R (VC), utilizados como suporte para o complexo Ni(II)(PAN)2. Os compósitos sintetizados foram caracterizados pelas seguintes técnicas: Microscopia Eletrônica de Transmissão (MET), Difração de Raios-X (DRX) e Voltametria Cíclica (VC). Os resultados obtidos por MET mostraram que o suporte de carbono Vulcan XC-72R possui mais espaços na superfície do que o Black Pearls 2000 e ambos, têm aproximadamente, o mesmo tamanho médio de partículas. A análise voltamétrica mostrou que o nanocompósito Ni(II)(PAN)2/BP apresentou menor separação entre os potenciais de pico (ΔEp) anódico e catódico, para o par Ni2+/Ni3+, em comparação com Ni(II)(PAN)2/VC, porém com menor densidade de corrente, referente a este par redox. A atividade eletrocatalítica dos nanocompósitos para oxidação de etanol foi avaliada pelas técnicas voltametria cíclica e cronoamperometria. Na voltametria cíclica, Ni(II)(PAN)2/BP apresentou pico de oxidação para etanol em 0,5 V e Ni(II)(PAN)2/VC apresentou pico de oxidação em 0,6 V, em solução de hidróxido de sódio 1 mol L-1 com concentração de 0,137 mol L-1 de etanol. Quanto as densidades de corrente obtidas na oxidação de etanol, Ni(II)(PAN)2/VC apresentou valores maiores do que Ni(II)(PAN)2/BP. Um estudo de tratamento térmico foi realizado para o nancompósito Ni(II)(PAN)2/VC em virtude deste ter apresentado maiores densidades de corrente para oxidação de etanol. Este material tratado termicamente (a 500, 600 e 700°C) foi caracterizado e testado eletroquimicamente para oxidação de etanol, e comparado com o nanocompósito preparado a 25°C. O tratamento térmico teve influência significativa em propriedades como: morfologia, tamanho da partícula tanto do suporte quanto do metal, estrutura e atividade eletrocatalítica. O nanocompósito tratado a 500°C apresentou melhor desempenho eletrocatalítico para oxidação de etanol.