Dissertations / Theses on the topic 'Methylene oxidation'

4’ -ester analogues of resveratrol were synthesized using reaction conditions developed to produce mono-ester products in the presence of two other unprotected phenols. Basic conditions were employed to deprotonate the most acidic 4’ phenol followed by addition of anhydrides or acid chlorides to give the ester product. The reaction favored 4’-ester formation in polar aprotic solvents with DMSO being the optimal solvent. (—)-Englerin A is a guaiane-type sesquiterpene containing two ester side chains. Mimics of (—)-englerin A were proposed that retained the ester side chains while replacing the non-polar core with less complicated structures. These proposed mimic cores would maintain the three-dimensional positioning of the esters which are responsible for the anti-cancer activity of (—)-englerin A. Three mimics were synthesized using the bicyclic terpenes borneol and fenchol. Installation of the second ester on the terpene core was accomplished throught the development and optimization of a unique methylene oxidation using chromium trioxide in glacial acetic acid. These mimics were screened against two kidney cancer cell lines. The compounds were shown to have IC50 (inhibitory concentration for 50 % of cells) values above 30 µM.

O DNA é um alvo constante de modificações químicas, as quais resultam na ativação dos programas de reparo de danos no DNA. O DNA mitocondrial (DNAmt), uma molécula circular contendo aproximadamente 16,6 kb de extensão, é constantemente exposto às espécies reativas de oxigênio (EROs) devido a sua proximidade da cadeia transportadora de elétrons, presente na membrana mitocondrial interna. Quase todas as vias de reparo de DNA presentes no núcleo atuam também na mitocôndria, entretanto, a regulação das vias mitocondriais não é bem compreendida. As proteínas p53, ATM, mTOR e PGC1α participam, dentre outros papéis, do controle do metabolismo energético e das respostas a lesões no DNA nuclear. Dessa forma, decidimos gerar linhagens celulares com níveis reduzidos dessas proteínas como uma ferramenta para o estudo dos seus papéis na manutenção do DNAmt. Para isso, foram geradas linhagens celulares de HEK293 expressando constitutivamente shRNAs alvo-específicos, cuja diminuição da expressão das proteínas alvo foi confirmada através de western blotting. Neste trabalho, também foi estudado o papel de p53 na resposta ao estresse oxidativo mitocondrial provocado por azul de metileno (AM). O AM é um corante fotoativo capaz de atravessar membranas biológicas e, em células de mamíferos, se acumula em organelas, tais como a mitocôndria. Uma vez que p53 participa de diversas funções celulares e transloca para a mitocôndria sob condições de estresse, onde pode induzir apoptose ou modular o reparo de DNAmt, nós investigamos se p53 está envolvido na indução de morte celular após tratamento com AM fotoativado. Para isso, foram utilizados 2 clones com níveis reduzidos de p53 obtidos na primeira etapa deste trabalho. Sob condições normais, foi demonstrado que o silenciamento de p53 induziu uma forte redução do número de cópias de DNAmt e estimulou a proliferação celular quando fornecemos glicose ou galactose como substratos energéticos. A depleção de p53, ou a sua inibição farmacológica, resultaram em uma ligeira proteção quando as células foram submetidas ao tratamento com AM. Também foi demonstrado que AM provoca morte celular apoptótica de uma maneira dependente de p53, uma vez que a depleção dessa proteína protegeu a população do acúmulo de células em sub-G1. Portanto, nossos resultados sugerem que AM induz morte celular apoptótica em células HEK293, de uma maneira dependente de p53. Esse efeito pode ser mediado diretamente por p53, ou ainda, pelo seu papel na manutenção do número de cópias do DNAmt.
DNA is constantly being chemically modified, which results in activation of the DNA damage response program. The mitochondrial DNA (mtDNA), a circular molecule of 16.6 kb in length, is primary target of reactive oxygen species (ROS) due its proximity to the electron transport chain, in the mitochondrial inner membrane. Almost all known DNA damage repair pathways operating in the nucleus were also found in the mitochondrion; however, their regulation remains not well understood. The proteins p53, ATM, mTOR e PGC1α have many cellular functions, including control of energy metabolism and cell fate after stress. Thus, we hypothesized that those proteins could participate in maintaining of mtDNA, through direct or indirect roles. To test this hypothesis, we generated isogenic knockdown cell lines to further use them to study their role in the mtDNA damage response. For that, were generated HEK293 knockdown cell lines that stably express target-specific shRNAs. Efficient knockdown was checked using western blotting. Here, we also studied the role of p53 in the cellular response to mitochondrial oxidative stress induced by methylene blue (MB). MB is a photoactive dye that crosses biological membranes due to its lypophylic character and, in mammalian cells, accumulates in organelles such as mitochondria; however, its cytotoxic mechanism is not well understood. As the p53 protein participates in several cellular functions and translocates to mitochondria under stress conditions, where it can induce apoptosis or modulate mtDNA repair, we investigated whether p53 was involved in MB + light-induced cell death using p53 knockdown clones selected from the cell lines generated in the first phase of this work. Under normal conditions, p53 knockdown caused a decrease in mtDNA copy number and stimulated cellular growth supported by either glucose or galactose. After MB treatment, p53-kd cells showed a slight decrease in cell death compared to scrambled shRNA controls. Evaluation of cell death after MB treatment, using flow cytometry analysis, indicated that MB was able to induce significant levels of apoptotic cell death, which was dependent on p53 levels. Taken together, our results suggest that MB induces cell death, probably via apoptosis, in a p53 dependent manner. This effect may be mediated by p53 directly or by its role in mtDNA copy number maintenance.

Philosophiae Doctor - PhD
The aim of this study was to design and build an electrohydraulic discharge reactor in such a way that the synthetic immobilized TiO2 nanophotocatalytic components could be integrated, for the production of active species such as OH radicals, ozone and hydrogen peroxide, as a cocktail to clean drinking water without the addition of chemicals. The research objectives include: • To design and construct the different AOP prototypes based on various electrode configurations and compare their operation. • To optimize the discharge parameters and conditions of the best AOP system. • To determine the effectiveness of the best prototype for the degradation of methylene blue as model pollutant. • To compare the designed AOP system with the Sodis method for the disinfection of contaminated river water. • To prepare supported TiO2 nanoparticles via electro spinning, followed by combustion and study the effect on the morphology of TiO2 nanoparticles. • To determine the stability and robustness of composite nano-crystalline TiO2 photocatalysts by sonication • To determine the enhanced effect of combining the composite TiO2 in the AOP system on degradation of methylene blue under the same conditions. • To detect the active species promoting disinfection.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of this study was to evaluate the effects of methylene blue (MB) photosensitizer (PS) solubilized in ethanol in antimicrobial photodynamic therapy (aPDT) as an adjuvant periodontal treatment, at oxidative stress (OS) parameters and vascular behavior in rat model. Besides, investigate greater involvement of angiogenesis at the destruction or healing stages of periodontal disease (PD). One hundred and twenty male adult Wistar rats were divided randomly into five groups. The control groups were negative control (NC) (no PD, n=15) and positive control (PC) (with PD, without any treatment, n=15). The other groups had PD and underwent different types of treatment, such as scaling and root planing (SRP) and irrigation with 1mL of saline solution (SRP, n=30); SRP and aPDT with MB solubilized in water (aPDT I, n=30); SRP and aPDT with MB containing ethanol (aPDT II, n=30). The PD was induced via the installation of a ligature around the mandibular right first molar. After 7 days, the ligature was removed and animals received treatment. At 7, 15 and 30 days, rats were euthanized and the gingival tissue surrounding the induction area was removed for histomorphometric analysis of the number and diameter of blood vessels by staining with hematoxylin and eosin (H&E). The collected blood was centrifuged and the plasma was used to determine lipid peroxidation by quantifying thiobarbituric acid reactive substances (TBARS), vitamin C (VIT C) and glutathione reduced (GSH) levels. The oxidative status showed higher TBARS levels in PC group in 7, 15 and 30 days, and indicated a protective influence of aPDT II on plasma observed from lower lipid peroxidation. GSH levels were consumed in PC, aPDT I and aPDT II groups throughout the experiment. Furthermore, aPDT II also increased antioxidant defenses in plasma: i) higher levels of GSH, and ii) increased levels of VIT C. Interestingly, the VIT C plasmatic levels were restored in the aPDT II group in the 30th experimental day. Histomorphometric findings in 7 days showed that treated groups (SRP, aPDT I and aPDT II) showed higher number of blood vessels, and the aPDT II group showed the highest values among them. From these results, aPDT modifies PD course, reducing oxidative systemic damage and stimulating the antioxidant defense system, thus protecting the areas closely affected by PD in rats. Moreover, was observed a relationship between increased expression of angiogenesis and repair stage of the PD. In summary, we suggest that the aPDT with MB solubilized in ethanol provides better therapeutic responses in periodontal treatment.
O objetivo deste estudo foi avaliar os efeitos do fotossensibilizador (Fs) azul de metileno (AM) solubilizado em etanol na terapia fotodinâmica antimicrobiana (TFDa) como um tratamento periodontal adjuvante, sob parâmetros de estresse oxidativo (EO) e de comportamento vascular em modelo de rato. Bem como, investigar o maior envolvimento da angiogênese no estágio de avanço ou reparo da doença periodontal (DP). Cento e vinte ratos Wistar adultos machos foram randomizados e divididos em cinco grupos. Os grupos controles eram controle negativo (CN) (sem DP, n = 15) e controle positivo (CP) (com DP, sem qualquer tratamento, n = 15). Os demais grupos apresentavam DP e foram submetidos a diferentes tipos de tratamentos, como raspagem e alisamento radicular (RAR) e irrigação com 1 mL de solução salina (RAR, n = 30); RAR e TFDa com AM solubilizado em água (TFDa I, n = 30); RAR e TFDa com AM contendo etanol (TFDa II, n = 30). A DP foi induzida através da colocação de uma ligadura ao redor do primeiro molar inferior direito. Após 7 dias, a ligadura foi removida e os animais receberam tratamento. Aos 7, 15 e 30 dias, os ratos foram eutanasiados e o tecido gengival circundante à área de indução foi removido para análise histomorfométrica do número e diâmetro dos vasos sanguíneos através da coloração com Hematoxilina e Eosina (HE). O sangue recolhido foi centrifugado e o plasma foi utilizado para determinar os níveis de peroxidação lipídica mensurados pelas substâncias reativas ao ácido tiobarbitúrico (TBARS), vitamina C (VIT C) e glutationa reduzida (GSH). O status oxidativo demostrou maiores níveis de TBARS no grupo CP em 7, 15 e 30 dias, e indicou uma influência protetora da TFDa II no plasma observada a partir de menor peroxidação lipídica. Níveis de GSH foram consumidos nos grupos CP, TFDa I e TFDa II durante o experimento. Ainda, TFDa II também aumentou as defesas antioxidantes no plasma: a) níveis mais elevados de GSH, e b) aumento dos níveis de VIT C. Interessantemente, os níveis plasmáticos de VIT C foram restaurados no grupo TFDa II no trigésimo dia experimental. Os achados histomorfométricos mostraram em 7 dias que os grupos tratados (RAR, TFDa I e TFDa II) apresentaram elevado número de vasos sanguíneos, e o grupo TFDa II apresentou os maiores valores entre eles. A partir destes resultados, fica evidente que TFDa modifica a DP, reduzindo o dano oxidativo sistêmico, e estimula o sistema de defesa antioxidante, protegendo, assim, as zonas afetadas intimamente pela DP em ratos. Além disso, foi observado uma relação entre a maior expressão da angiogênese e o estágio de reparo da DP. Em síntese, sugerimos que a TFDa com AM solubilizado em etanol proporciona melhores respostas terapêuticas no tratamento periodontal.

A Terapia Fotodinâmica (TFD) é uma modalidade terapêutica promissora que tem mostrado resultados clínicos efetivos, a lém de custo benefício favorável ao sistema de saúde. Embora a TFD esteja associada à indução de morte celular por necrose e, ou apoptose, pesquisas recentes comprovam a ativação da autofagia. Visando entender a relação entre a quantidade de espécies reativas de oxigênio (EROs), produzidas após fotoativação dos fotossensibilizadores (FSs), com a indução de morte autofágica, foram utilizados os FSs fenotiazínicos estruturalmente semelhantes, azul de metileno (MB) e 1,9-dimetil azul de metileno (DMMB); as linhagens celulares HeLa e HaCat, como modelos biológicos e LEDs emitindo em 633 nm, como fonte luminosa. Os ensaios de viabilidade em função da dose de luz e da concentração dos FSs verificaram que o aumento de morte celular está diretamente relacionado ao aumento da concentração e ao aumento da dose de luz, para ambos FSs. Verificou-se que nas condições de IC50 a concentração do DMMB (10 nmol/L) é menor que a do MB (2,0 µmol/L) em duas ordens de grandeza, e essa diferença também se reflete no grau de desbalanço oxidativo gerado após fotossensibilização. Foi verificado que para o MB, a elevada geração de EROs está fortemente correlacionada com a perda de viabilidade, enquanto que para o DMMB essa correlação é fraca, uma vez que há perda de sobrevida sem grandes gerações de EROs. No entanto, a diminuição de sobrevida causada pelo DMMB se correlaciona forte e significativamente ao aumento da autofagia, indicando ocorrência de morte celular autofágica tanto em células HaCaT quanto em células HeLa. As análises de dano em organelas indicaram que ambos FSs, após serem fotoativados, causam danos em lisossomas e em mitocôndrias de células HaCaT. E confirmou-se, por ensaio de localização subcelular, que ambos FSs estão nessas organelas. Uma vez que a localização subcelular do FS influencia no mecanismo de morte celular foto desenvolvido, verificou-se que o MB nas mesmas concentrações nanomolares do DMMB não induz autofagia, pois o mesmo encontra-se fotoquimicamente inativo nas mitocôndrias, devido à redução pelas coenzimas presentes nesta organela. O DMMB possui um potencial de redução menor que o MB, o que impede a redução deste FS nas mitocôndrias, e, mesmo em baixas concentrações, o DMMB é capaz de comprometer a integridade de mitocôndrias e lisossomas, e induz ir autofagia como um mecanismo de morte celular. As condições em que o MB não se encontra totalmente reduzido no ambiente celular são em concentrações mais elevadas, nas quais a geração do nível de estresse oxidativo é maior e não se observa resposta autofágica após fotossensibilização. Esses resultados mostram que a eficiência de morte celular causada por TFD não está necessariamente relacionada ao nível de estresse oxidativo gerado, uma vez que o DMMB induziu estresse oxidativo em menor extensão do que MB e, no entanto, induziu morte celular em maior extensão. Confirmou-se o conceito de que, fotossensibilizadores mais eficazes para a TFD devem resultar da melhoria na especificidade das reações de fotossensibilização nos alvos celulares e não apenas em melhoria na eficiência de geração de ERO.
Photodynamic Therapy (PDT) is a promising therapeutic modality that has shown effective clinical outcomes and benefits in terms of costs to the national health system. Although PDT is associated with induction of cell death by necrosis or apoptosis, recent data suggest the activation of autophagy. In order to understand the relationship between reactive oxygen species (ROS), generated after light activation of photosensitizers (PSs), and the autophagic cell death induction, we have used two phenothiazines with similar structure - methylene blue (MB) and 1,9-dimethyl methylene blue (DMMB); HaCaT and HeLa cells were used as biological models and LEDs emitting at 633 nm were used as light source. Cell viability assays as function of light dose and PS concentration showed that the increase in cell death was directly proportional to the PS concentration and light dose, to the both PSs. At IC50 was verified that DMMB concentration (10 nmol/L) is lower than MB concentration (2,0 µmol/L) in two order of magnitude, and this difference is reflected in degree of oxidative stress promoted by photosensitizers . Only for MB the amount of detected ROS is highly correlated with loss of cell viability, while for DMMB this correlation is weak, because there is loss of viability without large generation of ROS. Nevertheless, the viability decreased for DMMB is highly correlated with the increase of autophagy, indicating occurrence of autophagic cell death in both HaCaT cells and in HeLa cells. The analyses of damaged cell organelles indicated that both PSs, after be photoactivated, induce lysosomal and mithochondrial damage in HaCaT cells. And the subcellular localization assay confirmed that DMMB and MB are localized in these organelles. Because the subcellular localization of PSs influences cell death mechanisms, this research identified that MB, in the same nanomolar concentration of DMMB, does not induce autophagy, because it is photochemically inactive in mitochondria due the reducing coenzymes present in this organelle. DMMB has a lower reduction potential than MB, which hinders PS reduction in mitochondria, and possibly generate a mild oxidative stress that compromise the integrity of mitochondria and lysosomes, and justify autophagy induction as a cell death mechanism. The conditions that MB is not fully reduced in the cellular environment are at higher concentrations, in which was detected high level of oxidative stress and autophagic cell death was not observed after photosensitization. These results show that the efficiency of cell death induced by PDT is not necessarily related with oxidative stress level, since the oxidative stress induced by DMMB was lesser than by MB, however, the cell death was greater. This research confirms the concept that more effective photosensitizers for PDT means greater specificity of photosensitization reactions, and not only improvement of the efficiency of ROS generation.

Neste trabalho investigamos efeitos de fotoirradiação e toxinas sob membranas celulares miméticas. Foram utilizadas, como modelo de membranas lipídicas, vesiculas unilamelares gigantes (GUVs) compostas pro lipídeos oxidados e não oxidados observadas por microscopia ótica de contraste de fase. Inicialmente estudamos a foto-resposta de membranas compostas por POPC e POPG dispersas em solução contendo azul de metileno (MB). Na sequência, estudamos o efeito de toxinas formadoras de poros, Esticolisina I (ST I) e Esticolisina II (ST II), em membranas contendo lipídeos oxidados e não oxidados. Os resultados de MB (10 µM) disperso em solução de membranas compostas por POPC e o lipídeo aniônico POPG indicaram que o aumento da densidade de carga negativa nas membranas das GUVs, que favorece a ligação da moléculas positivamente carregadas como MB nas membranas, tem como consequência um aumento de permeabilidade da membrana muito mais rápído em relação a membranas compostas apenas por POPC. Isto se deve ao fato que a localização preferencial do MB na membrana de POPC:POPG favorece a formação de oxigênio singlete próximo a dupla ligação da cadeia alquílica, dando início a reação de peroxidação lipídica de maneira mais efetiva que em membrana de POPC. Os resultados da ação das toxinas STI e STII (21 nM) em GUVs contendo lipídeos não oxidados PC e esfingomielina evidenciam que apenas STII é capaz de permear estas membranas a esta concentração. Mais ainda, nossos resultados sugerem que a existência de separação de fases fluida-gel na bicamada lipidica composta por PC:SM (razão molar 1:1) favorece a ação da toxina StII. Ao analisarmos membranas contendo lipídeos hidroperoxidados (POPC-OOH) dispersas em solução contendo STII (21 nM) observamos um aumento de permeabilidade na membrana num conjunto de GUVs, associado a formação de poros, apenas em bicamadas lipídicas formadas por misturas de lipídeos oxidados (POPC) e não oxidados (POPC-OOH). Quanto maior a concentração de lipídeos oxidados na membrana mais rapidamente ocorre o aumento de permeabilidade.
In this work we investigate the effects of photoirradiation and toxins on mimetic cell membranes. As a model of lipid membranes, giant unilamellar vesicles (GUVs) composed of oxidized and oxidized pro-lipids were observed by optical phase contrast microscopy. Initially we studied the photo-response of membranes composed of POPC and POPG dispersed in solution containing methylene blue (MB). Following, we studied the effect of pore-forming toxins, Sticolysin I (ST I) and Sticolysin II (ST II), on membranes containing oxidized and non-oxidized lipids. The results of MB (10 M) dispersed in solution of membranes composed of POPC and the anionic lipid POPG indicated that the increase in the negative charge density in the membranes of GUVs, which favors the binding of positively charged molecules as MB in the membranes, consequently increases membrane permeability in regard to membranes composed only of POPC. This is due to the fact that the preferred location of the MB in the POPC: POPG membrane favors the formation of singlet oxygen near the double bond of the alkyl chain, initiating the lipid peroxidation reaction more effectively than in the POPC membrane. The results of the action of the STI and STII toxins (21 nM) on GUVs containing non oxidised lipids PC and sphingomyelin show that only STII is able to permeate these membranes at this concentration. Moreover, our results suggest that the existence of fluid-gel phase separation in the lipid bilayer composed of PC:SM (molar ratio 1:1) favors the action of the StII toxin. When analyzing membranes containing hydroperoxidized lipids (POPC-OOH) dispersed in solution containing STII (21 nM) we observed an increase in membrane permeability in a set of GUVs, associated with pore formation, only in lipid bilayers formed by mixtures of oxidized lipids (POPC-OOH) and non-oxidized ones. The higher the concentration of oxidized lipids in the membrane, the faster the permeability increases.

Lack of function of ALDP in mouse leads to a late onset disease, characterized by spastic paraparesis and degeneration of corticospinal tracts, without signs of inflammatory demyelization resembling AMN patients. Taking advantage of this mice model and using primary glia cultures, we investigated the role of inflammation (mainly the pro and anti-inflammatory pattern) in X-ALD mice spinal cord and studied the contribution of microglia and astrocytes in disease pathogenesis. We found X-ALD mice spinal cord shows an inflammatory imbalance at 12 months of age. Similar observations were found in case of X-ALD mice primary microglia. In addition, we found mitochondria as the source of ROS in X-ALD mice microglia when insulted with C26:0. Activation of CB2 receptor prevents microgliosis and recovers all the altered parameters in X-ALD mice and thus halts axonal degeneration. Similar neuroprotective effects were observed with Methylene blue by targeting mitochondria.
La ausencia de función de ALDP en ratón conduce a una enfermedad tardía caracterizada por paraparesia espástica y degeneración del tracto corticoespinal sin signos de desmielinización inflamatoria, semejante a pacientes con AMN. Aprovechando este modelo y utilizando cultivos primarios de glía, hemos investigado el rol de la inflamación en la médula espinal del ratón X-ALD y la contribución de microglía y astrocitos en la patogénesis de la enfermedad. Hemos observado que la médula espinal muestra un desequilibrio inflamatorio a los 12 meses de edad. El mismo patrón se ha encontrado en cultivos primarios de microglía provenientes del mismo modelo, identificando además a la mitocondria como su fuente de ROS, tras tratarla con C26:0. Se han observado efectos neuroprotectores tales como la prevención de microgliosis y la recuperación de todos los parámetros alterados en los ratones los X-ALD, tanto activando los receptores CB2 como atacando dianas mitocondriales con azul de metileno.

Etude comparative des proprietes redox de treize clustres du co, rh, fe effectuee par des methodes electrochimiques (edt, coulometrie, voltamperometrie cyclique) associees a des methodes spectroscopiques (uv, rmn, rpe)

L'etude des proprietes redox d'une vingtaine de complexes mono-, di-, tri- et tetranucleaires du palladium et du platine a ete effectuee par des methodes electrochimiques (electrode a disque tournant, voltamperometrie cyclique et coulometrie) associees a des methodes spectroscopiques (spectrophotometrie d'absorption electronique, rpe et rmn). Les differents mecanismes des reactions redox ont ete etablis en fonction de la nature des metaux et des ligands dans le complexe. On montre qu'on peut modifier de maniere controlee les potentiels d'oxydoreduction et la reversibilite des transferts de charge par un choix convenable de parametres: metaux, ligands (phosphine, co) et milieu d'etude. Les resultats obtenus contribuent a l'etude de la reactivite electrochimique de la liaison metal-metal dans les complexes des metaux de transition

Dans cette thèse sont présentées des études consacrées à l'élimination des composés organiques soufres volatils issus principalement de l'industrie de la pâte à papier kraft et à leur dégradation par oxydation en utilisant le peroxyde d'hydrogène en présence de catalyseurs métalliques. Nous avons utilisé des catalyseurs des produits de recyclage de déchets de l'industrie pétrochimique contenant mo et co. L'optimisation des conditions de traitement thermique pour une dépollution du catalyseur a été faite. Nous avons également étudié par microscopie électronique à balayage, diffraction rx et spectrométrie auger, l'évolution des matériaux déchets au cours de leur traitement thermique. Nous avons monté un générateur de gaz étalon par cellule à diffusion. Dans une brève partie nous avons utilisé avec opportunité la méthodologie mise au point pour mettre en évidence la décomposition photo-catalytique sur tio2 du sulfure de diméthyle. Dans une partie de ce travail, nous avons effectué des mesures cinétiques sur la photo-oxydation de sulfure de diméthyle et du disulfure de diméthyle. La mesure des constantes de vitesse a été réalisée par cinétique compétitive dans une chambre de simulation atmosphérique. Les résultats montrent une grande réactivité avec le radical oh. Nous avons également identifié les produits de la réaction du dms et du dmds avec le radical oh: le so2 et l'acide méthane sulfonique sont les produits majoritaires

A via de Reparo por Excisão de Nucleotídeos (NER) é responsável pelo reparo das lesões causadas pela luz ultravioleta (UV) e de outras lesões capazes de distorcer a dupla hélice, bloqueando a replicação e a transcrição. Os pacientes que apresentam as síndromes recessivas raras Xeroderma Pigmentosum (XP), tricotiodistrofia (TTD) e síndrome de Cockayne (CS) possuem mutações em algum dos 11 genes relacionados ao NER e à transcrição basal. Mutações na proteína XPD levam ao surgimento de diferentes fenótipos: XP, TTD, XP/CS ou COFS (Cerebro-Oculo-Facio-Skeletal Syndrome), uma forma rara de CS. Os pacientes XP apresentam alta incidência de câncer de pele, o que não ocorre com os pacientes TTD e CS, além de poderem apresentar perda neuronal progressiva, enquanto todos os CS e TTD apresentam uma diminuição na mielinização do cérebro. As neuropatologias são provavelmente associadas a problemas no reparo de danos endógenos no DNA das células nervosas. Diversos trabalhos mostraram o envolvimento do NER no reparo desses danos, os quais pensava-se serem reparados apenas por outro mecanismo, o Reparo por Excisão de Base. Neste trabalho mostramos que fibroblastos de pacientes XP-D, XP-D/CS e TTD, portadores de mutações em XPD, são sensíveis ao estresse oxidativo induzido pelo tratamento com azul de metileno fotoativado, apresentando bloqueio prolongado no ciclo celular e permanência da sinalização de danos ao DNA. A complementação das diferentes linhagens com o gene XPD/ERCC2 foi capaz de restaurar a sobrevivência celular. Foram detectadas diferenças importantes na capacidade de reparo/retomada da transcrição após danos gerados por estresse oxidativo em DNA plasmidial, além da ativação de vias diferentes de morte celular: fibroblastos XP-D apresentam maior capacidade de reparo e apresentam morte por apoptose após estresse oxidativo, enquanto os fibroblastos XP-D/CS e TTD apresentam menor capacidade de reparo ativação de mais de uma via de morte celular (apoptose e necrose), diferenças que podem estar ligadas ao fenótipo dos pacientes. Mutações no gene codificante para a DNA polimerase n, POLH, estão associadas à forma variante de XP (XP-V). Pol n é uma polimerase especializada na síntese translesão (TLS) de fotoprodutos, além de estar implicada na TLS de outros tipos de lesões como bases oxidadas, e em vias não relacionadas à TLS como a hipermutação somática e à replicação de regiões de DNA com arquiteturas não-canônicas. Neste trabalho mostramos que os fibroblastos de pacientes XP-V apresentam sensibilidade ao estresse oxidativo. Mostramos uma indução da proteína pol n em fibroblastos primários após danos genotóxicos, associada ao aumento da capacidade de lidar com a parada na forquilha de replicação, possibilitando a continuidade da replicação do DNA e ao aumento da sobrevivência celular. Mostramos uma diferença na estabilidade genômica nos genes das imunoglobulinas dos pacientes XP-V idosos em comparação com os pacientes jovens e controles de idade pareada, mostrando que a ausência dessa polimerase pode estar ligada ao aumento da instabilidade genômica nesses genes
The Nucleotide Excision Repair (NER) pathway is responsible for the repair of UV photoproducts and other bulky lesions that block both replication and transcription. Patients with the rare recessive disorders Xeroderma Pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne Syndrome (CS) carry mutations in one of the 11 NER genes, linked to repair and basal transcription. Mutations in XPD lead to different phenotypes: XP, TTD, XP/CS or COFS (Cerebro-Oculo-Facio-Skeletal Syndrome), a rare form of CS. XP patients have high incidence of skin cancer, which does not occur in TTD or CS patients, although ther may present neurodegeneration, while all CS and TTD patients have neurodevelopmental symptoms linked to dysmielynation. The pathology of these neurological diseases is probably associated with deficient repair of DNA lesions in nervous cells, generated by endogenous processes. Many groups including ours have demonstrated the involvement of NER in the repair of these lesions, previously thought to be exclusively repaired by Base Excision Repair. In this work we show high sensitivity of both primary and transformed XP-D, XP-D/CS and TTD human fibroblasts in response to oxidative stress generated by photoactivated methylene blue, with prolonged cell cycle arrest and DNA damage signaling. The complementation of the three different cell lines with the XPD/ERCC2 gene was able to restore cell survival. We detected important differences in repair capacity/transcription resumption after damage generated by oxidative stress in plasmid DNA, besides the activation of different cell death pathways: XP-D cells have higher repair capacity and die by apoptosis, while XP-D/CS and TTD cells have little repair capacity and activate more than one death pathway (apoptosis and necrosis). We believe these differences can be related to the patients\' phenotypes. Mutations in DNA polymerase n coding gene, POLH, are associated with the variant form of XP (XP-V). Pol n is a translesion synthesis (TLS) polymerase specialized in the TLS past CPD photoproducts, besides other lesions like oxidized bases, and in other processes like somatic hypermutation and DNA replication in structured regions. In this work we show XP-V human fibroblasts are sensitive to oxidative stress. We detected an induction of pol n after genotoxic stress in primary cells, associated with increased ability to deal with the stalled replication fork, and consequently to DNA replication restart and cell survival. In addition, we detected a difference in genomic stability in immunoglobulin genes in aged XP-V patients in comparison to both young patients and age-matched controls, showing the absence of this polymerase may be linked to increased genomic instability in these genes

碩士
嘉南藥理科技大學
環境工程與科學系曁研究所
97
In this study, we prepared four nano catalysts including CeO2、CeO2/Apatite、TiO2 and CeO2/TiO2 for the catalytic wet air oxidation of methylene blue(MB). Via rate of color removal and COD removal, performance of the catalysts was evaluated to screen for the optimal one and reaction condition of the most active catalyst was also investigated. The results indicated that the efficacy of WAO without catalyst of 100 ppm methylene blue improved with temperature at O2 partial pressure of 1.5Mpa, which implied heat decomposition occurred in a certain temperature. The characterization of catalysts of SEM shows the diameter of CeO2、TiO2 and CeO2/TiO2 catalysts are around 15 to 21nm, and the BET analysis are around 39 to 47m2/g. With the smallest diameter and largest surface area, TiO2 catalyst performed the most active among the four. At the condition of 100 ppm methylene blue concentration, 180℃, 1.0 g/L the catalyst loading and 1.5 MPa of O2 pressure, the color removal and COD removal after 4 hrs reaction are 95% and 38.5%, respectively. The rate of COD removal at temperatures of 180~200°C increased as reaction temperature increased, while at temperatures of 200~220°C, the COD removal decreased with increase in reaction temperature, suggesting an optimum temperature for the operation of this catalyst of 200°C. An optimal loading was found at 1.0 g/L, when free radical formation is higher at a lower catalyst loading (0.5~1.5g/L), while at a higher loading (1.5~3.0g/L), free radical destruction dominates. The suitable O2 partial pressure occurred at 1.0Mpa. The intensity of the TiO2 crystals peaks increased calcination temperature increased, while the 515℃ calcinated-temperature catalyst is superior to 300°C and 700℃calcinated-temperature catalyst on CWAO performance with his more structure defects. As for the assessment of catalyst regeneration and durability, it was found that the order of color removal for 50ppm MB with fresh catalyst and regenerated catalyst was: calcined again > reused > fresh catalyst > alcohol > rinsed with acetone, and also the order of COD removal was: fresh catalyst > calcined again > reused > alcohol > rinsed with acetone, which showed calcined again was the best catalyst regeneration method in the study. In addition, we selected the second most active catalyst, CeO2/HA, for the CWAO of MB by varying Cerium content. The result indicated that the most active catalyst was CeO2/HA(1:1/8), which performed better activity than TiO2 catalyst. The efficacy of this catalyst increased as the MB concentration increased. At the condition of 2600ppm MB solution, it enabled 99.75% of color removal and 91.89% of COD removal after 4 hrs reaction, which confirmed this catalyst was feasible for high concentration of reactants.

碩士
國立中興大學
環境工程學系所
98
Sodium persulfate can be thermally activated to produce sulfate radicals (SO4-‧) (E0 = 2.6 V). It has been demonstrated that under acidic condition, SO4-‧ is the dominant oxidant radical species; in neutral condition, the SO4-‧ can proceed radical interconversion reaction with hydroxyl ions to generate the hydroxyl radical (OH‧); at alkaline condition, OH‧is the major oxidant radical species. Due to that the interaction between different radicals and specific pollutants is dependent of pH and hence the destruction of various pollutants varies at various pHs, this study focused on the deduction of the kinetics of thermally activated persulfate oxidation of methylene blue (MB) at acidic (pH = 3), neutral (pH = 7) and alkaline (pH = 11) conditions. Moreover, the reaction rate constant between MB and SO4-‧and the concentrations of both SO4-‧and OH‧were determined. The kinetic results of persulfate oxidation of MB revealed that at 60, 70 and 80°C under pH = 3, 7 and 11, the decolorization of MB achieved > 95 % at around 1 hour. The degradation of MB was found to follow pseudo-first-order kinetics model. The effect of pH on MB decolorization rate was pH 11 > pH 3 > pH 7; the effect of temperature was 80°C > 70°C > 60°C. At 70 and 80°C under pH = 3, 7 and 11, the removal of total organic carbons (TOC) reached > 90 % after around 1 hour while at 60°C under pH 3, 7 and 11 TOC removals were 37, 30, and 57 %, respectively. It was also demonstrated that the reaction rate constant between SO4-‧ and MB is around 108 M-1s-1, and confirmed that at acidic (pH 3) condition, SO4-‧, with concentration of ~ 10-6 M and reaction activation energy (Ea) = 87.17±2.09 kJ/mole, is the dominant radical; at neutral (pH 7) condition, SO4-‧, with concentration of ~ 10-11 M, and OH‧ , with concentration of ~ 10-10 M, are simultaneously present, Ea = 109.06±2.70 kJ/mole; at alkaline (pH 11) condition, OH‧, with concentration of ~ 10-6 M, is the major radical, Ea = 89.68±2.21 kJ/mole.

碩士
國立中山大學
化學系研究所
104
Industrial dyes are an increasingly important class of wastewater pollutants that cause serious environmental and health issues. Such dyes, when left untreated result in chemical and biological changes to the aquatic environment, as well as being toxic to humans. Advanced Oxidation Processes (AOPs) involve more than one type of oxidation mechanism. These reactions accelerate production of the hydroxyl radical and hydroperoxyl radical, which are highly reactive and can degrade organic compounds and dyes. The AOP technique utilizes Fenton’s reagent, ultra violet (UV) radiation, and ozone (O3). In the first part of our experiment, we synthesized the bimetallic alloy Fe3O4/CuO, and used ICP-MS to monitor the Cu/Fe alloy ratio. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the structure of the nanoparticles. A superconducting quantum interference device (SQUID) confirmed the magnetic properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical state of the nanoparticle alloy constituents. We selected methylene blue (MB) as the target molecule to test the Fe-Cu-0.8 alloy in the presence of hydrogen peroxide while monitoring the reaction with UV-Vis spectroscopy. After 60 minutes, the Fe-Cu-0.8 alloy decolorized MB to 95% at pH 4. Kinetic analysis confirmed that this was a first order reaction. In the second part of the experiment, we determined that the Fe-Cu-0.8 alloy can also degrade p-Nitrophenol under the same reaction conditions. Finally, we determined the best conditions for reaction and repeated the experiment 5 times to confirm that the Fe-Cu-0.8 can be recycled. Our results suggest that the Fe-Cu-0.8 alloy may be a good candidate for AOP catalytic degradation of dyes and other organic pollutants.

碩士
中原大學
生物環境工程研究所
104
Copper and other precious metals have been widely used in electrical and electronic materials however due to innovation, as materials are made in miniature scale, wastes of the outdated products from these industries have been increasing; thus, the need to recover precious metals from it are also increasing. Toxic contaminants in wastewater from industries have also been increasing therefore development of technologies to remove it have been a great focus of environmental research institutions. In this study, copper waste was recovered from electronic and electrical wastes to produce a catalyst that can be used to degrade methylene blue dye via catalytic wet hydrogen peroxide oxidation. The catalyst was prepared by simple hydrothermal method. The oxidation was done with the aid of hydrogen peroxide (H2O2) to react with copper oxide, the reactor was utilized with controlled heat to encourage the production of hydroxyl radicals from the synthesized product and H2O2. From the results of leaching copper waste it was found that HNO3 has given the best recovery for copper leaching. It has been found that the synthesized copper oxide, that used copper obtained from the waste, can degrade up to 99% of 50 mg/l of methylene blue solution after 45 minutes in a controlled reactor with a temperature of 45 ○C while the copper oxide made from commercial copper has degraded 98%. The results of FTIR has shown agreement with other related literatures, showing vibrational peaks of Cu2O and CuO at around 626 and 531 cm-1, respectively.

碩士
國立中正大學
化學暨生物化學研究所
107
Nanoparticles have the properties of high surface energy, high specific surface area, and high ratio of surface atoms. Nanoparticles may act as catalysts to reduce the activation energy of chemical reactions and therefore to increase reaction rates. Gold nanoparticles (AuNPs) have strong catalytic activity when the sizes of the particles reduce to 2~5 nm. The gold nanoparticles with the sizes less than 10 nm, however, are difficult to be collected by centrifugation. Literature had used commercial metal oxide as the support for small AuNPs. However, the quantitative evaluation of the catalytic ability is difficult because of the irregular shape of metal oxide. Herein, we used a spherical titanium dioxide as a support for AuNPs, making them easier for centrifugation and reuse. Monodispersed TiO2 nanoparticles (TiO2NPs) were prepared by using acetonitrile and 1-butyl alcohol as the solvent to control the precipitation rate of the hydrolysis product of titanium butoxide (Ti(OBu)4). The ammonium is used as the shape controller for the formation of spherical TiO2 nanoparticles. By using 0.1 M NH3+0.76 M H2O, the averaged particle size is 320 ± 35 nm. In the synthesis of TiO2@AuNPs, we obtained AuNPs with the diameter of 15±3.8 nm by using L-ascorbic acid as a reducing agent. However, the distribution of AuNPs on the surface of TiO2NPs was uneven. We used sodium borohydride (NaBH4) as a reducing agent and found the best synthesis conditions of TiO2@AuNPs were: (1) The amount of TiO2NPs solution was 10 mL. (2) The amount of gold salt solution (5×10-3 M) was 3.0 mL. (3) The water bath temperature of the reaction was 25 °C. NaBH4 is a strong reducing agent. The particle sizes of AuNPs are small (d=2~5 nm) by using NaBH4, and AuNPs are uniformly dispersed on the surface of each titanium dioxide sphere. We used methylene blue (MB) oxidation reaction to examine the catalytic ability of TiO2@AuNPs nanocomposites. We added TiO2NPs or TiO2@AuNPs to the oxidation reaction of methylene blue by H2O2. The absorbance of MB at 664 nm wavelength in the absence of a catalyst, decreased at the rate of ΔA/Δt = –0.0029 abs/min. When we added TiO2NPs, the absorbance of MB at 664 nm decreased at the same rate as ΔA/Δt = – 0.0029 abs/min. Therefore, the TiO2NPs did not have a catalytic ability. When we added different TiO2@AuNPs, the oxidation reaction rate of absorbance of MB at 664 nm increased 30~45 times (k = 0.11~0.16 min-1) as that in absence of a catalyst (k = 0.0035 min-1). We proposed that the H2O2 obtains electrons from the surface of TiO2NPs to form HO2•, OH- and •OH radicals. These free radicals attack MB to oxidize MB. The AuNPs obtain electrons from the MB molecules which are oxidized by the free radicals, and the electrons subsequently transfer from the AuNPs to the TiO2NP support.

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia
The main purpose of the present work is the analysis and development of an electro-oxidation process with activated carbon that gives it a third dimension (EO3D). This dissertation was developed in a business environment, in VentilAQUA S.A. As case study, a synthetic effluent with a common dye in the textile industry (methylene blue, MB) was used.Initially, the most relevant variables of the process, namely flow rate, current intensity and electrical conductivity were identified. Using a Design of Experiments (DOE), their statistical relevance was evaluated. As a result, the factors identified as relevant were the flow rate and current intensity. Thus, a multiple linear regression model was constructed. The model was validated with experimental results not used in its construction. In addition, two simpler models (with fewer factors) were also proposed, that are able to properly describe the behavior of the system. Based on DOE results, additional tests were performed using smaller flow rates (longer residence times) than those previously tested. In this case it was possible to obtain MB removal efficiencies around 67%, for a flow rate of 2.4 L / h and a current intensity of 1.5 A.The 3D electro-oxidation was also evaluated as a technique for the regeneration of saturated activated carbon. The regeneration treatment involved two saturation cycles (24 h each) and one regeneration cycle (1 h). The results obtained are promising since the regenerated activated carbon showed adsorption capacity of about 90%.Overall, this study allowed to conclude that EO3D has potential, not only for textile industry wastewater treatment, but also for the regeneration of previously saturated activated carbon.
O principal objetivo deste trabalho é a análise e desenvolvimento de um processo de eletro-oxidação com carvão ativado que lhe confere uma terceira dimensão (EO3D). O trabalho foi desenvolvido em ambiente empresarial, na VentilAQUA S.A. Como caso de estudo foi utilizado um efluente sintético com um corante comum na indústria têxtil (azul de metileno, AM).Numa primeira fase, foram identificadas as variáveis potencialmente mais relevantes do processo, designadamente o caudal, a intensidade de corrente e a condutividade elétrica. Com recurso a um desenho de experiências (DOE) foi avaliada a sua relevância estatística. Na prática os fatores identificados como relevantes foram o caudal e a intensidade de corrente. Assim, foi contruído um modelo de regressão linear múltipla. O modelo foi validado com resultados experimentais não utilizados na sua construção. Adicionalmente, foram também propostos dois modelos mais simples (com menos fatores), que permitem também descrever adequadamente o comportamento do sistema. Com base nos resultados do DOE, foram realizados testes adicionais utilizando caudais menores (maiores tempos de residência) do que os anteriormente testados. Neste caso foi possível obter eficiências de remoção de AM da ordem dos 67%, para um caudal de 2,4 L/h e uma intensidade de corrente de 1,5 A.A eletro-oxidação 3D foi também avaliada como técnica de regeneração de carvão ativado saturado. O tratamento de regeneração envolveu dois ciclos de saturação (24 h cada) e um de regeneração (1 h). Os resultados obtidos são promissores dado que o carvão ativado regenerado revelou capacidade de adsorção de cerca de 90%.Globalmente, este estudo permitiu concluir que a EO3D tem potencial, não só para a depuração de efluentes da indústria têxtil, como também para a regeneração de carvão ativado previamente saturado.

Dissertação de mestrado em Ciências e Tecnologias do Ambiente (área de especialização em Energia)
Processos de oxidação avançados (POA’s) têm demostrado ser um método efetivo para o tratamento de efluentes da indústria têxtil. Os POA’s oxidam as moléculas orgânicas, como corantes, utilizando radicais hidroxilo (OH•) gerados em reações de fotocatálise. O dióxido de titânio (TiO2) é o catalisador mais associado com este processo, mas apresenta a desvantagem de apenas ser ativado com radiação ultravioleta (UV). Para obter um catalisador funcional na zona do espectro visível utilizou-se antes o titanato de cobalto (CoTiO3) dopado com zinco e/ou flúor. Neste trabalho foram preparadas de perosvkites mistas com propriedades catalíticas de (ZnxCo1-x)TiO3, dopadas com flúor. As partículas foram caracterizadas por DRX e espectrometria UV/Vis. Os testes para avaliar a capacidade fotocatalítica: ensaios de fotodegradação de moléculas orgânicas usando o azul de metileno como modelo e medição da capacidade de geração de radicais hidroxilo através da fluorescência do ácido 2-hidroxitereftálico. Os catalisadores que apresentaram maiores taxas de catálise foram aqueles com maior conteúdo de cobalto e os dopados com flúor.
Advanced oxidation processes (AOPs) have proven to be an effective method for the treatment of effluents from the textile industry. POA's oxidize organic molecules, such as dyes, using hydroxyl radicals (OH •) generated in photocatalysis reactions. Titanium dioxide (TiO2) is the catalyst most associated with this process, but it has the disadvantage of only being activated with ultraviolet (UV) radiation. To obtain a functional catalyst in the visible spectrum, TiO2 was doped with the cobalt, zinc and fluorine ions. In this work were prepared perovskites (ZnxCo1-x) TiO3, doped with fluorine with catalytic properties. The particles were characterized by XRD and UV / Vis spectrometry. Tests were carried out to evaluate photocatalytic capacity in two ways: photodegradation tests of organic molecules using methylene blue as a model and fluorometry for hydroxyl radical generation capacity. Higher rates of catalysis presented in those with higher content of cobalt and doped with fluoride.

碩士
國防醫學院
公共衛生學研究所
96
This cross-sectional study aimed to evaluate the healthy effects of MBOCA exposure and the relationship to oxidative stress damage and genotoxicity and to discuss the modification effect between genetic polymorphism (CYP3A4) and MBOCA exposure. The study population was recruited from four MBOCA-manufacturing factories in Taiwan. We divided the study population into exposure group(total MBOCA≧20μg/g creatinine) and control group (total MBOCA<20μg/g creatinine) by the total MBOCA concentration of urine and chose 49 persons for each group after matching with gender and age.The personal characteristics, occupational history, and lifestyle were collected by the self-adminstrated questionnaire. Urine was collected to measure total MBOCA concentration and 8-Hydroxydeoxyguanosine (8-OHdG) as oxidative stress index. We analysed the the mean number of micronucleate cells and CYP3A4 polymorphism in the lymphocyte form blood sample. The results showed no difference between exposed workers and controls for 8-OHdG but exposed group was significantly higher than control group for the mean number of micronucleate cells. The impact of MBOCA exposure on the high mean number of micronucleate cells was analysed by logistic regression model adjusted for smoking, drinking tea and CYP3A4. The odds ratio was 9.26 (95% CI: 1.83-46.66) in the MBOCA exposure group and the odds ratio was 4.33 (95% CI: 1.20-15.67) in CYP3A4 mutation type. Our study suggested exposed to MBOCA could induce genotoxicity, and mean number of micronucleate cells was a good indicator to evaluate genotoxicity. Persons who CYP3A4 RS2246709 genotype were mutation type, they were genotoxicity more serious There was not interaction between MBOCA exposure and CYP3A4 polymorphism. We will use another funtional mutation to find the interaction between environment exposure and gene in the future.

Alzheimer's disease (AD) is a neurodegenerative condition affecting millions of individuals worldwide and is a major source of mortality in elderly populations. While it is well established that there is a strong genetic basis for the disease, the epigenetic mechanism underlying the disease is largely unknown. The main purpose of this thesis is to understand the alteration of epigenetic modifications associated with the disease and its progression. In particular, we examine how alterations in the cytosine methylation and cytosine hydroxymethylation, two epigenetic modifications that are critically important for the development and function of the brain, are associated with advancing stages of Alzheimer's disease. Eight progressive AD brain samples were examined for changes in DNA methylation and hydroxymethylation by both dot blot analysis and a new oxidative bisulfite (OXBS) deep sequencing technology. The initial results of dot blot analysis reveal a statistically significant decrease in 5hmC associated with intermediate stage AD among the samples. This data suggests that the alterations in epigenetic modifications is likely associated with the pathophysiology of Alzheimer's disease, not only shedding new light on our understanding of the epigenetics of the disease, but also providing the basis for our future investigation on the exact cause and effect relationships of these epigenetic changes and their respective stages in Alzheimer's.