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Made available in DSpace on 2014-10-09T12:28:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:37Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:28:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:37Z (GMT). No. of bitstreams: 0 / Neste trabalho foram estudadas as propriedades espectroscópicas do íon európio trivalente complexado à componentes da família das tetraciclinas, a clorotetraciclina, oxitetraciclina e metaciclina, em presença de peróxido de hidrogênio e peróxido de uréia. Para isso foram obtidos os parâmetros ópticos de absorção, emissão, tempo de vida e construídas curvas de calibração para os espectros de luminescência. Realizaram-se experimentos com compostos inorgânicos juntamente com os complexos a fim de verificar a interferência dos mesmos. Também foram realizados estudos para determinação de glicose utilizando os complexos európiotetraciclinas como biossensor. Os resultados mostram que os complexos európiotetraciclinas apresentam um espectro de emissão bem definido na região do visível e, na presença de peróxido de hidrogênio ou peróxido de uréia, há um aumento sensível na luminescência e tempo de decaimento. Assim, os complexos európiotetraciclinas estudados podem ser utilizados como biossensores para determinação dos peróxidos de hidrogênio e uréia, sendo um método realizado em temperatura ambiente, direto e de baixo custo. Um método indireto para determinação de glicose foi estudado através da adição da enzima glicose oxidase aos complexos európiotetraciclinas na presença de glicose no qual há como produto o peróxido de hidrogênio. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientadores: Giselle Maria Marchi, Carlos Alberto de Souza Costa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T06:19:18Z (GMT). No. of bitstreams: 1 Lima_AdrianoFonsecade_M.pdf: 16947758 bytes, checksum: c368a477af40a0e63ffe78a57bea6537 (MD5) Previous issue date: 2009 / Resumo: Os objetivos do presente trabalho foram: a) avaliar os efeitos citotóxicos diretos e transdentinário de diferentes concentrações de peróxido de carbamida (PC) sobre as células de linhagem odontoblástica MDPC-23; b) avaliar o efeito protetor (antioxidante) do ascorbato de sódio (AS) sobre estas células expostas a agentes clareadores, na forma direta e transdentinária; c) avaliar o montante de peróxido de hidrogênio (H2O2) liberado por agentes clareadores a base de PC 10% e 16% que se difunde através de discos de dentina com 0,5mm de espessura. No Experimento 1, células odontoblásticas foram cultivadas em wells e incubadas por 48 horas. O gel clareador foi solubilizado em meio de cultura (DMEM) originando diferentes extratos, e a quantidade (µg/mL) de H2O2 liberado em cada extrato foi mensurada através da técnica de leucocristais violeta/enzima horseradish peroxidase (LCV/HRP). Os seguintes grupos foram estabelecidos (n=10): G1-DMEM sem gel clareador (controle); G2-0,0001% PC (0,025µg/ml de H2O2); G3-0,001% PC (0,43µg/ml de H2O2); G4-0,01% PC (2,21µg/ml de H2O2); e G5-0,1% PC (29.74µg/ml de H2O2). As células foram expostas por 60 minutos aos diferentes extratos, e então realizada a análise da viabilidade celular (Teste de MTT). Somente os grupos 2 e 3 não apresentaram diferença estatística quando comparados ao controle (G1) (p>0,05). Os maiores efeitos citotóxicos foram observados para G4 e G5, sendo que G5 foi estatisticamente diferente que G4, apresentando-se mais tóxico às células. No experimento 2, células MDPC-23 foram cultivadas e incubadas por 48h. O PC e o AS foram solubilizados em meio de cultura (DMEM), para obtenção dos extratos experimentais. Os seguintes grupos foram estabelecidos: G1-DMEM sem gel clareador (controle); G2- 0,25mM de AS; G3-0,5mM de AS; G4-0,25mM de AS + 0,01% de PC; e G5-0,5mM de AS + 0,01% PC e G6-0,01% de PC. As células foram expostas por 60 minutos aos diferentes extratos, e depois foi realizado o teste de MTT. O grupo 6 apresentou a maior citotoxicidade quando comparado com os demais grupos, enquanto que o AS produziu uma diminuição dos efeitos citotóxicos do agente clareador, demonstrando uma proteção frente aos componentes deste produto. No Experimento 3, discos de dentina (0,5mm de espessura) obtidos de terceiros molares humanos foram fixados em uma câmara pulpar artificial (CPA). As células odontoblásticas foram semeadas na superfície pulpar dos discos, e os seguintes grupos foram estabelecidos: Grupo 1 - Sem tratamento (Controle); Grupo 2 - Antioxidante 10% (AS)/6h; Grupo 3- Peróxido de Carbamida (PC) 10% /6h; Grupo 4- AS10%/6h+PC10%/6h; Grupo 5- PC16% /6h; Grupo 6- AS10%/6h+PC16%/6hs. Após os tratamentos, foi realizado o teste de MTT. A difusão de H2O2 somente para os grupos 3 e 5 foi mensurada através da técnica de LCV/HRP. Todos os grupos foram estatisticamente semelhantes, exceto o G6. O PC 16% apresentou a maior difusão transdentinária. Pode-se concluir que o PC apresenta efeitos citopáticos para as células odontoblásticas MDPC-23, na forma direta ou transdentinária e que esta citotoxicidade é dose-dependente. O ascorbato de sódio possui a capacidade de reduzir os efeitos citotóxicos do peróxido de carbamida, sobre estas mesmas células em cultura. / Abstract: The aims of this present study were: a) to evaluate the direct and transdentinal cytotoxic effects of carbamide peroxide (CP) bleaching gel at different concentrations on odontoblast-like cells MDPC-23; b) to evaluate the protective effect (antioxidizing) of sodium ascorbate (SA) on these cells expose to bleaching agents, on direct and transdentinal mode; c) to evaluate the amount of hydrogen peroxide (H2O2) released by bleaching agents based to CP 10% and 16%, that diffuses through dentin discs with 0.5mm thickness. In Experiment 1, odontoblastic cells were seeded in wells and incubated for 48 hours. The bleaching gel was diluted in DMEM culture medium originating different extracts, and the amount (µg/mL) of H2O2 released from each extract was measured by the leukocrystal violet/horseradish peroxidase enzyme (LCV/HRP) assay. The following groups were established (n=10): G1-DMEM without bleaching gel (control); G2-0.0001% CP (0.025 µg/mL H2O2); G3-0.001% CP (0.43 µg/mL H2O2); G4-0.01% CP (2.21 µg/mL H2O2); and G5-0.1% CP (29.74 µg/mL H2O2). MDPC-23 cells were exposed to the bleaching gel extracts for 60 minutes and then performed the cell viability analysis (MTT assay). Only G2 and G3 were not significantly different from control group (G1) (p>0.05). The most severe cytotoxic effects were observed in G4 and G5, and G5 was statistically different to G4, presenting more toxic to the cells. In Experiment 2, MDPC-23 cells were seeded in wells and incubated for 48 hours. CP and SA were dissolved in culture medium (DMEM) in order to obtain the experimental extracts. The following groups were established: G1-no treatment (control); G2-0,25mM SA; G3-0,5mM SA; G4-0,25mM SA + 0,01% CP; e G5-0,5mM SA + 0,01% CP e G6-0,01% CP. The cells were expose to different extracts for 60 min, and then was performed the MTT assay and. Group 6 presented higher cytotoxicity than the other groups, while the SA decreased the cytotoxic effects caused by CP, demonstrating its protective effect against the toxic components of this dental product. In Experiment 3, dentin discs (0.5mm thick) obtained from human third molars were fixed in an artificial pulp chamber (APC). The odontoblastic cells were seeded on pulp surface of the discs, and the following groups were established: Group 1 - No treatment (Control); Group 2 - Antioxidizing 10% (SA)/6h; Group 3- Carbamide Peroxide (CP) 10%/6h; Group 4- SA10%/6h+CP10%/6h; Group 5- CP16%/6h; Group 6- SA10%/6h+CP16%/6hs. After the treatments, MTT assay was performed. The H2O2 diffusion only to the groups 3 and 5 was measured by the LCV/HRP assay. All groups were statistically similar, except G6. The CP 16% presented the higher transdentinal diffusion. It can be conclude that CP presents citotoxic effects to the odontoblastic-like cells MDPC-23, in direct and transdentinal mode and this citotoxicity is dose-dependent. The sodium ascorbate was able to reduce the cytotoxic effects the concentration of 0.1% of PC caused the most intense cytopathic effects of carbamide peroxide on the same cells in culture. / Mestrado / Dentística / Mestre em Clínica Odontológica

Abstract Information about interactions among metals, hydrogen peroxide and chelating agents is needed to develop environmental technology and the operating efficiency of modern elemental chlorine free and total chlorine free bleaching processes. The work presented here focused on the properties of metal chelates and corrosion of titanium in an alkaline hydrogen peroxide solution. A comparative study between three rapid analysis methods, ICP-AES, XRF and ISE, was performed in pulp matrix and error sources of ISE were investigated in detail. Sensitive and selective GC methods for chelating agents ADA and NTA in water matrices were developed. Decomposition of ADA (percentage of residual 71) was observed already at the hydrogen peroxide anion level of 400 mg/l in which DTPA was more persistent (percentage of residual 94). EDTA was stable even in the hydrogen peroxide anion level of 1200 mg/l, in which its percentage of residual was 94. DTPA, EDTA and ADA were more soluble in the presence of iron and manganese than in the absence of these metals. The chelation of iron appeared to be thermodynamically limited in hydrogen peroxide bleaching conditions. Unalloyed (Grade 2) and alloyed (Grade 5) titanium corroded at the hydrogen peroxide anion level of 200 mg/l. The presence of calcium and silica inhibitors and further iron and manganese enhanced the critical hydrogen peroxide anion levels. Grade 5 was inferior to Grade 2. During rapid uniform corrosion, the potential of unalloyed titanium was under 200 mV (SHE) and lower than that of platinum. Over 90% of manganese and many other metals could be leached into aqueous phase for ICP-AES analysis using chelation or acid hydrolysis. An XRF method for manganese, iron and copper in pulp including little or no sample treatment was developed. Measuring temperature differences and atmospheric carbon dioxide were observed to be notable error sources of the ISE technique.

Due to the toxicity and prevalence of BTEX contaminants (benzene, toluene, ethylbenzene, and xylenes) at hazardous waste sites, approaches for their remediation are of interest, especially those that particularly address benzene, which is often the limiting factor for achieving regulatory cleanup at these contaminated sites. In situ chemical oxidation (ISCO) is a viable technology for BTEX destruction, and hydrogen peroxide and sodium persulfate are two oxidants of interest for BTEX treatment.Laboratory studies were conducted to compare BTEX contaminant destruction and oxidant persistence for these two oxidants and for varied methods of oxidant activation/propagation. Additionally, studies were performed to compare contaminant destruction and oxidant persistence in laboratory contaminant spike systems vs. field site contaminant systems. Finally, contaminant destruction and oxidant persistence in field porous media with varied characteristics were evaluated. Contaminant and oxidant concentrations were measured at multiple time points over a three-week reaction period in each oxidant and oxidant activation/propagation system.Under the comparable conditions evaluated here, sodium persulfate systems demonstrated greater BTEX contaminant destruction and greater oxidant persistence than hydrogen peroxide systems. FeSO4 and citric acid activation of sodium persulfate resulted in greater BTEX destruction and greater oxidant persistence than pH adjustment or hydrogen peroxide activation in both laboratory contaminant spike systems and field gas condensate systems. Additionally, results indicate that the response of the contaminant(s) and oxidant (extent and rate of depletion) are both contaminant-and porous media type-dependent.

Streptococcus pneumoniae (pneumococcus) is a major human pathogen and commensal organism of the nasopharynx. A major virulence factor of the pneumococcus is the cholesterol dependent, pore forming cytolysin pneumolysin. This toxin acts extracellularly, but the mechanism of release has not been well elucidated. Despite being a catalase negative organism, the pneumococcus produces up to millimolar concentrations of hydrogen peroxide through the activity of pyruvate oxidase. In all strains analyzed, deletion of the pyruvate oxidase gene yielded a significant reduction in the amount of PLY observed in the supernatant via western blot. A single strain, WU2 was also observed to have a significant (p<.05) reduction in the amount of PLY observed in the supernatant when treated with extracellular catalase. Furthermore, a significant correlation between hydrogen peroxide production and PLY release was observed in a panel of 15 clinical isolates.

This thesis reports the outcome of a simulation study that examines the feasibility of using hydrogen peroxide as an alternative oxidant in the autothermal reforming (ATR) of diesel. The primary objective is to compare hydrogen peroxide's performance against conventional oxidants in reforming, focusing on product distribution and three pivotal process properties: diesel conversion, hydrogen production, and ethylene generation. The study further investigates the influence of the heat of decomposition on the performance and reaction routes of different oxidants. Additionally, a comparative analysis is conducted on the reforming performance in different reformer configurations, specifically contrasting a combined-reformer-configuration with a catalytic-reformer configuration. The ANSYS Chemkin-Pro is utilized to understand the potential benefits and challenges of the proposed approached. A reduced chemical mechanism of N-heptane/Toluene reforming as a surrogate for diesel, combined with a detailed surface reaction mechanism of propene on a three-way Pt/Rh catalyst are used in this study. It is found that the use of hydrogen peroxide as an oxidant demonstrated a complete fuel conversion and 183% higher hydrogen yield when compared with conventional oxidants. It also led to a 12% lower generation of ethylene, a precursor for coke formation. The catalytic-reformer configuration showed superior performance over the combined-reformer-configuration in terms of hydrogen yield. The insights from this study offer valuable perspectives on the feasibility and efficiency of using hydrogen peroxide as an alternative oxidant in the ATR of diesel, paving the way for potential advancements in the field.

The entire epidermis of patients with vitiligo exhibits accumulation of up to 10-3M concentrations of hydrogen peroxide (H2O2) (Schallreuter, Moore et al. 1999). Over the last decade our group and others have focused on the effect of H2O2-mediated oxidative stress on the function of many proteins and peptides due to oxidation of target amino acid residues in their structure including L-methionine, L-tryptophan, L-cysteine and seleno cysteine (Rokos, Beazley et al. 2002; Gillbro, Marles et al. 2004; Hasse, Kothari et al. 2005; Schallreuter, Chavan et al. 2005; Spencer, Chavan et al. 2005; Chavan, Gillbro et al. 2006; Elwary, Chavan et al. 2006; Gibbons, Wood et al. 2006; Schallreuter, Bahadoran et al. 2008; Shalbaf, Gibbons et al. 2008; Wood, Decker et al. 2009). Moreover, it was shown that patients with vitiligo possess up regulated wild type functioning p53 protein in their skin (Schallreuter, Behrens- Williams et al. 2003). The reason behind this up regulation has remained unclear (Schallreuter, Behrens-Williams et al. 2003). Therefore the aim of this thesis was to get a better understanding of these puzzling data. Along this project different techniques have been used including Western blot, dot blot, immuno precipitation, immuno fluorescence, EMSA and computer modelling. In this thesis we confirmed the previous result on up regulation of p53 in vitiligo and we showed that p90MDM2, the master regulator for p53 protein is not different in patients and healthy controls. Therefore we decided to test for expression of p76MDM2 which mediates the inhibition of p90MDM2-p53 binding. Our results show for the first time the presence and over expression of p76MDM2 protein in vitiligo compared to 3 healthy individuals. This result could provide an explanation, why up regulated p53 is not degraded in this disease. Since epidermal H2O2 accumulation has been extensively documented in vitiligo, we wanted to know whether other ROS could also contribute to the overall oxidative stress in this scenario. Therefore we turned our interest to nitric oxide (NO) and its possible effects on p53 protein. In order to elucidate this role in more detail, the expression levels of epidermal nitric oxide synthesase (iNOS) and the oxidation product of NO and O2 - i.e peroxynitrite (ONOO-) were investigated. Our data revealed over expression of iNOS and nitrated tyrosine residues, the foot print for ONOO-. Moreover, we show for the first time the presence of abundant nitration of p53 protein in vitiligo. In addition using purified p53 from E. coli strain (BL21/DE3) and mutant p53 protein from HT-29 cells (colon cancer cells), we show that nitration takes place in a dose and time dependent manner. On this basis we investigated the effect of both H2O2 and ONOO- on p53-DNA binding capacity employing EMSA, since this is the most acceptable technique to follow the binding between proteins and DNA. Our results revealed that ONOO- abrogated p53-DNA binding capacity at concentrations >300 ¿M, meanwhile oxidation of p53 protein with H2O2 at the same concentrations does not affect binding capacity. Importantly, a much higher p53- DNA binding capacity was observed after exposure to both ONOO- and H2O2. Taken together, p53 is regulated by both ROS (H2O2) and RNS (ONOO-). Next we identified the presence of phosphorylated and acetylated p53 in vitiligo. Phosphorylation of ser 9 and ser 15 residues of the protein are associated with over expressed ATM protein kinase, while acetylation of lys 373, 382 residues correlates with increased PCAF expression. We show that up regulated p53 is associated with over expressed p21 (cyclin dependent kinase inhibitor 1) and induced PCNA 4 expression. Hence, we can conclude that p53 in patients with vitiligo is up regulated, activated and functional. Finally we show up regulated BCL-2 supporting the long voiced absence of increased apoptosis in vitiligo. Given that patients with vitiligo have no increased risk for solar induced skin cancer and increased photo damage (Calanchini-Postizzi and Frenk 1987; Westerhof and Schallreuter 1997; Schallreuter, Tobin et al. 2002), despite the presence of increased DNA damage as evidenced by increased 8-oxoG levels in the skin and in the plasma, our findings suggest that both p53 and PCNA provide a powerful machinery to mediate DNA repair via hOgg1, APE1 and DNA polymerase ß (Shalbaf 2009). On this basis it is tempting to conclude that DNArepair is the overriding mechanism to combat oxidative stress in this disease. / Egyptian government; Institute for Pigmentary Disorders in association with the EM Arndt University of Greifswald, Germany.

Many soil and aquifer systems in the United States have been subjected to chemical contamination from past industrial and military activities. While many remediation technologies are currently being applied, in situ chemical oxidation (ISCO) is one option that is often favored because of its potential for fast remediation times and high user control. This technology involves the direct injection of chemical oxidizers (e.g. hydrogen peroxide, ozone, or permanganate) into targeted contaminant zones within the subsurface, and it has been proven to be amenable to both BTEX compounds and other volatile organic compounds such as chlorinated solvents. This study had several key objectives. Firstly, multiple soil samples, each containing an elevated level of a targeted chemical constituent, were successfully collected in order to provide a wide range of soil types in order to make important comparisons and correlations related to ISCO?s impacts. Secondly, the impact of common soil constituents on process reagent transport was studied in order to determine which soil constituents would act as primary hindrances for the transport of hydrogen peroxide and ozone into the subsurface. Thirdly, experiments were performed to pinpoint certain personnel safety threats such as excess oxygen and heat generation that might arise during process application. Fourthly, the impact of ISCO process application on soil fabric properties was examined. Soil aerobic microbial populations, soil hydraulic conductivity, soil natural organic matter constituents, and soil adsorptive properties were all shown to be impacted following the application of chemical oxidizers.