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Percorrer por autor "Oliveira, Nuno Guerreiro"

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    Redox modulation by sod mimics in renal cancer: from etiology to progression
    (2017) Costa, João Guilherme Feliciano da; Escola de Ciências e Tecnologias Saúde; Fernandes, Ana Sofia; Oliveira, Nuno Guerreiro; Lucio Cazaña, Francisco Javier
    Cancer is a multistep process and oxidative stress has been pointed out to have critical roles on its initiation, promotion and progression. This thesis addresses the redox modulation afforded by the superoxide dismutase mimic (SODm) MnTnHex-2-PyP (MnP), a prototype of the Manganese(III) porphyrins (MnPs), which are catalytical polyfunctional antioxidants with the ability to modulate different cellular redox pathways. Two different renal cell models were used to address initiation and progression cellular events. Firstly, the role of MnP on the toxicity of non-tumor renal cells exposed to the ochratoxin A (OTA) was evaluated. The MnP protected cells from the OTA-induced cytotoxicity. In addition, it modulated the intracellular reactive oxygen species (ROS) levels and decreased the percentage of cells in apoptosis when compared with cells exposed only to OTA. The role of the MnP in renal cancer progression was subsequently studied in a human renal cancer cell model. MnP decreased the cell viability of human 786-O cells and also induced an increase in intracellular ROS. Notably, low concentrations of the MnP significantly decreased the chemotactic migration of the 786-O cells. This study contributed to clarify the role of oxidative stress in OTA-induced toxicity. In addition, this work revealed the potential of MnTnHex-2-PyP in renal cancer treatment, by decreasing cancer cells viability and migration. Overall, this MnP protected non-tumor cells from the toxic effects induced by OTA, while it had a beneficial effect against renal cancer cells. The results obtained herein reinforce the multiple potential applications of MnPs and warrant further studies towards their therapeutic use.
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    Stress oxidativo e defesas antioxidantes: uma revisão pedagógica
    (Edições Universitárias Lusófonas, 2011) Fernandes, Ana Sofia; Castro, Matilde; Oliveira, Nuno Guerreiro; Escola de Ciências e Tecnologias Saúde
    Nos últimos anos tem havido um interesse crescente pelos efeitos do stress oxidativo, e muitas evidências científicas indicam que este está envolvido em diversos fenómenos patológicos. O presente artigo pretende rever os conceitos de stress oxidativo e defesas antioxidantes, permitindo introduzir os profissionais e alunos da área da saúde nesta temática. Assim, são abordadas as principais vias de formação de espécies reactivas de oxigénio, assim como o processo de peroxidação lipídica. Este artigo foca também as defesas antioxidantes, especialmente as enzimas superóxido dismutases, catalase e glutationo peroxidases, que desempenham um papel central nas defesas celulares. São ainda referidos os efeitos deleténos do stress oxidativo, bem como alguns dos processos patológicos em que as lesões oxidativas estão envolvidas, e que justificam o interesse dos compostos antioxidantes.