Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: David J. Singel. Includes bibliographical references (leaves 55-56).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 126-136).

Thesis (M.S.)--Ohio University, June, 2005. / Title from PDF t.p. Includes bibliographical references (p. 77-88)

Thesis (Ph.D.)--Ohio University, November, 2004. / Title from PDF t.p. Includes bibliographical references (p. 137-159)

Thesis (Ph. D.)--University of Oregon, 2003. / Includes bibliographical references (leaves 137-145).

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 59-66). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11754

Orientador: Iracilda Zeppone Carlos / Banca: Antonio Eduardo Mauro / Banca: Denise Fecchio / Resumo: O câncer, manifestação originada pelo crescimento descontrolado de células, afeta milhões de indivíduos. Os macrófagos são as primeiras células a serem ativadas para participar de uma resposta imunológica propriamente dita, são células capazes de secretar mais de cem produtos biologicamente ativos, entre esses, espécies reativas de nitrogênio e citocinas que atuam no contexto da resposta imunológica e/ou inflamatória. Sabendo que compostos de paládio (II) podem apresentar potenciais atividades anti - tumorais, neste trabalho foram testado os compostos de fórmula geral [Pd(dmba)(Cl)tu] e [Pd(dmba)(N3)tu], nos quais dmba = N,N-dimetilbenzilamina e tu = tiouréia quanto a atividade antiinflamatória, antitumoral e mutagênica dos mesmos.Como droga padrão das reações realizadas foi utilizada a cis-platina. Foi determinada a ação destes compostos frente ao sistema imunológico através, de ensaios de determinação de citotoxicidade mediano (IC50) pela técnica de MTT, óxido nítrico (NO), peróxido de hidrogênio (H2O2), determinação das citocinas IL-1, IL-6, IL-12, TNF-α e IL-10. Além disso, foi determinado a atividade antitumoral dos compostos frente à célula tumoral de Ehrlich, assim como a atividade mutagênica pelo teste de Ames e Ensaio com plasmídio pUC 9.1. Os resultados mostraram produção de NO e das citocinas IL-1, IL-6, IL-12 e TNF-α; moderada produção de H2O2 pelos macrófagos peritoneais de animais normais e animais portadores do tumor de Ehrlich na sua forma sólida, estimulados com os compostos e seus ligantes, assim como a cis-platina. Por outro lado, de maneira contrária às outras citocinas testadas, não houve a produção de IL-10. No que se refere à atividade antitumoral dos compostos testados, estes mostraram efeito citotóxico sobre a linhagen tumoral testada. Com relação à atividade mutagênica, os compostos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The cancer, manifestation originated by the growth not controlled of cells, affects million of individuals. Macrophages are the first cells to be activated to participate in an immune response itself, are cells to able to secreting more than one hundred biologically active products, among these, reactive nitrogen species and cytokines that act in the context of the immune response and / or inflammatory. Knowing that compounds of palladium (II) can be potential activities anti - tumor in this study was tested compounds of general formula [Pd (Pd) (Cl) tu] and [Pd (Pd) (N3) tu], where Pd = N, N-dimetilbenzilamina and tu = thiourea as the anti-inflammatory, antitumor and mutagenic of the same. As standard was used the cis-platinum. We determining the action of these compounds against the immune system, for tests to determine the median cytotoxicity (IC50) by the MTT technique, nitric oxide (NO), hydrogen peroxide (H2O2), determination of IL-1, IL-6 , IL-12, TNF-α and IL-10. Moreover, it was determined the antitumor activity of compounds against the Ehrlich tumor cell, as well as mutagenic by the Ames test and test with plasmid pUC 9.1. The results showed NO production and the IL-1, IL-6, IL-12 and TNF-α, by peritoneal macrophages from normal animals and animals with Ehrlich tumor in solid form was stimulated by the compounds and their ligands as well as cis-platinum. Moreover, in contrary manner to other cytokines tested, there wasn't production of IL-10, and H2O2. With regard to the antitumor activity of the compounds tested, these showed cytotoxic effect on tumor lineage tested. With respect to mutagenic activity, compounds and ligands weren't mutagenic in vitro, unlike cis-platinum was shown to be mutagenic, causing mutations in the DNA of Salmonella typhimurium by the Ames test. The compounds and ligants were not also to induce DNA breaks in the plasmid... (Complete abstract click electronic access below) / Mestre

Pyruvate kinase catalyses the final step in glycolysis and is responsible for net ATP production. There are four pyruvate kinase isoforms expressed in humans; LPYK, RPYK, M1PYK and M2PYK. The allosteric enzyme M2PYK plays an important role in cancer cell metabolism and is subject to complex regulation by numerous naturally occurring small-molecule metabolites. Post-translational modifications have also been found to play a key role in the regulation of M2PYK, among these cysteine oxidation. This thesis describes the production and characterisation of M2PYK cysteine point mutants in order to investigate the mechanism of regulation by cysteine modification. From a total of ten cysteines present in M2PYK, five were chosen for mutation based on a combination of the results from the cysteine oxidation prediction program (COPP) web interface and published experimental evidence for cysteine modification of M2PYK. Eight point mutants of these five cysteines were produced and characterised. Low resolution gel filtration of all the mutants shows that mutation of these cysteines has an effect on tetramer:dimer:monomer equilibrium of M2PYK suggesting that cysteine modifications could regulate M2PYK activity by affecting oligomeric state. Activity assays show that none of the cysteine point mutations are sufficient to protect M2PYK from oxidation by H2O2 indicating that more than one cysteine is involved in the regulation of M2PYK by oxidation. Nitric oxide (NO) imbalance has recently emerged as playing a key role in numerous diseases including cancer. NO regulates the function of target proteins through the addition of a nitroso moiety from NO-derived metabolites to a reactive cysteine, a process known as protein S-nitrosylation. M2PYK has been found to be S-nitrosylated in vivo. Using the biotin-switch assay in vitro combined with mass spectrometry I have shown that a likely candidate for the target of S-nitrosylation of M2PYK is C326. This thesis also describes the structures of two cysteine point mutants; M2PYK C424A and M2PYK C358S. The structures show that these mutations have very little effect on the overall conformation of M2PYK with only very subtle localised changes. The structure of the mutant M2PYK C358S shows some interesting features including varying occupation of the active site resulting in differing conformations of the B domains within the same tetramer, and an unusual B factor distribution which could be indicative of a perturbation in cooperativity within the tetramer caused by the mutation.

Maintaining the intrinsic excitability of neurons is crucial for stable brain activity. This can be achieved by the homeostatic regulation of membrane ion channel conductances, although it is not well understood how these processes influence broader aspects of neuron and network function. One of the many mechanisms which contribute towards this task is the modulation of potassium channel conductances by activity-dependent nitric oxide signalling. Here, we first investigate this mechanism in a conductance-based neuron model. By fitting the model to experimental data we find that nitric oxide signalling improves synaptic transmission fidelity at high firing rates, but that there is an increase in the metabolic cost of action potentials associated with this improvement. Although the improvement in function had been observed previously in experiment, the metabolic constraint was unknown. This additional constraint provides a plausible explanation for the selective activation of nitric oxide signalling only at high firing rates. In addition to mediating homeostatic control of intrinsic excitability, nitric oxide can diffuse freely across cell membranes, providing a unique mechanism for neurons to communicate within a network, independent of synaptic connectivity. We next conduct a theoretical investigation of the distinguishing roles of diffusive homeostasis mediated by nitric oxide in comparison with canonical non-diffusive homeostasis in cortical networks. We find that both forms of homeostasis robustly maintain stable activity. However, the resulting networks differ, with diffusive homeostasis maintaining substantial heterogeneity in activity levels of individual neurons, a feature disrupted in networks with non-diffusive homeostasis. This results in networks capable of representing input heterogeneity, and linearly responding over a broader range of inputs than those undergoing non-diffusive homeostasis. We further show that diffusive homeostasis interferes less than non-diffusive homeostasis in the synaptic weight dynamics of networks undergoing Hebbian plasticity. Overall, these results suggest a novel homeostatic mechanism for maintaining stable network activity while simultaneously minimising metabolic cost and conserving network functionality.