Efeitos da injeção intracerebroventricular de peróxido de hidrogênio ou de ATZ sobre a resposta pressora da angiotensina II centralmente

As espécies reativas de oxigênio podem participar de mecanismos envolvidos em respostas fisiológicas, como os efeitos hipertensores e dipsogênicos da angiotensina II (ANG II) central, que seriam pelo menos em parte devidos a produção de radical superóxido (O2 −). Por isso, uma superexpressão da enzima superóxido dismutase que reduz a disponibilidade de O2 − convertendo-o em peróxido de hidrogênio (H2O2) inibiria o efeito pressor da ANG II administrada centralmente. Porém, alguns resultados de nosso laboratório demonstram que H2O2 injetado intracerebroventricularmente (icv) reduz a ingestão de água induzida pela ANG II em ratos normotensos. Portanto, no presente trabalho propomos estudar os efeitos de injeções de H2O2 ou de ATZ (inibidor da catalase) sozinhos ou combinados no ventrículo lateral (VL) e também os efeitos do ATZ injetado intravenosamente (i.v.) sozinho ou combinado com H2O2 no VL sobre a resposta pressora da ANG II também injetada no VL em ratos normotensos, espontaneamente hipertensos (SHRs) ou em ratos com hipertensão renovascular do tipo 2 rins 1 clipe (2R1C). Foram utilizados ratos Holtzman normotensos, SHRs e ratos com hipertensão renovascular 2R1C com cânulas de aço inoxidável previamente implantadas no VL. A pressão arterial e a freqüência cardíaca foram registradas em sistema computadorizado diretamente da aorta em ratos não anestesiados por uma cânula de polietileno introduzida pela artéria femoral e a injeção i.v. foi realizada por meio de uma cânula de polietileno introduzida na veia femoral. A pressão arterial e freqüência cardíaca foram registradas continuamente desde 30 minutos antes da primeira injeção (veículo, salina, H2O2 ou ATZ) até 30 minutos após a injeção de ANG II. Os resultados demonstraram que a injeção icv de H2O2 (5 μmol/1 μL) reduziu fortemente a reposta pressora produzida pela injeção... (Resumo completo, clicar acesso eletrônico abaixo)

Efeitos da ação central do peróxido de hidrogênio na ingestão de água, na excreção renal de água e eletrólitos e na expressão de Fos induzidos pela estimulação colinérgica da área sptal medial

A área septal medial (ASM), situada no prosencéfalo, está envolvida na regulação cardiovascular e no controle do balanço hidroeletrolítico. Esta área é rica em receptores colinérgicos e a ativação dos mesmos induz ingestão de água, natriurese e antidiurese. A ASM também envia projeções aos núcleos paraventricular (NPV) supra-óptico (NSO), os quais contêm os neurônios que secretam vasopressina e ocitocina. Existem evidências experimentais demonstrando que as espécies reativas de oxigênio podem participar do controle de respostas fisiológicas. Resultados recentes de nosso laboratório demonstraram que uma espécie reativa de oxigênio, o peróxido de hidrogênio (H2O2), injetado no ventrículo lateral (VL) reduz a ingestão de água e a resposta pressora induzida por ANG II e carbacol (agonista colinérgico) também injetados no VL. Por isso, o presente estudo teve como objetivo estudar os efeitos da injeção de H2O2 na ASM sobre a ingestão de água, sobre a excreção renal de água e eletrólitos e sobre a expressão da proteína c-Fos no NSO produzidos pela injeção de carbacol também na ASM. Para realizar este trabalho, foram utilizados ratos com cânulas de aço inoxidável implantadas na ASM. A ingestão de água e a excreção renal de água e eletrólitos foram estudadas em ratos que receberam injeções de H2O2 (5 mol/0,5 μl) ou PBS (veículo, 0,5 l) na ASM e, após um minuto, injeção de carbacol (4 nmol/0,5 l) ou salina (NaCl 0,15 M / 0,5 l) também na ASM. A ingestão de água induzida pelo carbacol, através da estimulação colinérgica, foi menor nos ratos que receberam a injeção prévia de peróxido de hidrogênio (8 ± 2,0 ml / 1 h, p<0,05) comparado àqueles que receberam veículo, também na ASM (16,6 ± 1,9 ml / 1 h, p<0,05). Além disso, houve diferença significativa na ingestão de água dos ratos + salina, grupo controle... (Resumo completo, clicar acesso eletrônico abaixo)

Otimização da extração alcalina com peróxido de hidrogênio em seqüência de branqueamento com aplicação de baixo fator kappa

The new market, focused on sustainability and other environmental concerns, refers to innovations that seek alternative forms of production. In pulp and paper bleaching alternative reagents are studied, for example, hydrogen peroxide, in partial substitution of chlorine dioxide in order to reduce the formation of organochlorines. In this context, this study examined the burden of hydrogen peroxide (H2O2) on alkaline extraction stage (stage Ep) required for the bleaching of pulp with eucalyptus kraft pulp, pre-oxygen delignified to obtain equivalent brightness at 90 ± 0.5% ISO, as well as its effect on quality of pulp produced. The pulp was bleached by the sequence D(Ep)DP, with the application of factor kappa of 0.14 and varying the concentration of hydrogen peroxide in Ep stage three, five, seven and nine kilograms of reagent per ton of pulp absolutely drought. The final P stage was optimized with the use of six, nine and twelve pounds of hydrogen peroxide per ton of absolutely dry pulp to achieve the required brightness. The quality of the pulp produced was analyzed based on the kappa number, the brightness and the viscosity. The methods were performed according to standards set by the standard TAPPI (Technical Association of the Pulp and Paper Industry). The best result was obtained using the following D0Ep(7)D1P(6), which showed a viscosity of 19.9 cP, 89.6% ISO brightness, consumption of 94.9 kg / t of reagents and reagent costs of US$ 28.15, because it showed better pulp quality for a lower cost compared to the others. It was found that the greater the amount of hydrogen peroxide in alkaline extraction, the lower the kappa number and increased the amount of residual hydrogen peroxide. The higher the charge of hydrogen peroxide in Ep stage, the lower the need for hydrogen peroxide in the final P stage, reducing the cost of bleaching

Apocinina versus diapocinina como inibidor da produção de peróxido de hidrogênio e ácido hipocloroso por neutrófilos ativados

Apocynin has been used as an efficient inhibitor of the multi-enzymatic complex NADPH oxidase in many experimental models involving phagocytic and nonphagocytic cells. The mechanism of inhibition has been linked with the previous activation of apocynin through the action of cellular peroxidases leading to the formation of a dimeric oxidation product, diapocynin. In this study we compared apocynin with pure diapocynin regarding their effects as scavenger of hydrogen peroxide and hypochlorous generated by glucose/glucose oxidase and myeloperoxidase respectively, and as inhibitors of the production of hydrogen peroxide and hypochlorous acid by activated neutrophils. The production of hydrogen peroxide was measured by the oxidation of the fluorescent substance Amplex Red and the production of hypochlorous acid by was measured as taurine-chloramine derivative using the chromogenic substrate 3,3’,5,5’- tetramethylbenzidine (TMB). Neutrophils (1 x106 cells/mL) were pre-incubated in PBS buffer supplemented with 1 mM calcium chloride, 0.5 mM magnesium chloride, 1 mg/mL glucose and 5 mM taurine in the presence or absence of inhibitors. The reactions were triggered by adding the soluble stimulus Forbol Miristate Acetate PMA or zymosan and incubated by additional 30 minutes. We found that pure diapocynin was not better than apocynin regarding its scavenger and inhibitory properties. These results suggest that the formation of diapocynin is not essential for the action of apocynin as inhibitor of NADPH oxidase activation

Efeito da ativação física e química do gel clareador na velocidade de penetração do peróxido de hidrogênio: estudo in vitro

This study evaluated the effect of physical and chemical activation on the speed of penetration of hydrogen peroxide bleaching agents present in different concentrations through the enamel and dentin. One hundred and twenty bovine incisors were used, which were obtained enamel/dentin discs of the buccal surface, with 6 mm in diameter. The samples were divided into six groups: G1 - Hydrogen Peroxide Gel 20%, G2 - Hydrogen Peroxide Gel 20% with light activation, G3 - Hydrogen Peroxide Gel 20% with Manganese Gluconate; G4 - Hydrogen Peroxide Gel 35%; G5 - Hydrogen Peroxide Gel 35% with the light activation and G6 - Hydrogen Peroxide Gel 35% with Manganese Gluconate. The specimens were placed in a transparent support on which there was a substance sensitive to hydrogen peroxide immediately below and in contact with the specimen. After the procedures for applying the gel for each group, one video camera was positioned and operated to monitor the time of penetration of peroxide in each specimen. The recording ended after changing the color of the fluid revealed in all specimens and times were noted for comparison. ANOVA analysis showed that concentration and type of activation of bleaching gel significantly influenced the diffusion time of hydrogen peroxide (P 0.05). 35% hydrogen peroxide showed the lowest diffusion times compared to the groups with 20% hydrogen peroxide gel. The light activation of hydrogen peroxide decrease significantly the diffusion time compared to chemical activation. The highest diffusion time was obtained with 20% hydrogen peroxide chemically activated. The diffusion time of hydrogen peroxide was dependent on activation and concentration of hydrogen peroxide. The higher concentration of hydrogen peroxide diffused through dental tissues more quickly

Influência da concentração de peróxido de hidrogênio nos agentes clareadores na cor e penetração através da estrutura dental

Pós-graduação em Odontologia Restauradora - ICT

Efeito citotóxico de agentes clareadores a base de peróxido de hidrogênio a 20% e 38% sobre células odontoblastóides

The aim of this in vitro study was to evaluate the trans-enamel and transdentinal cytotoxic effects of two in-office tooth bleaching techniques that employ bleaching gels containing 20% and 38% of H2 O2 on cultured odontoblast-like cell line (MDPC-23). Sixty enamel/dentin discs were obtained from bovine central incisors and placed individually in artificial pulp chambers. Six groups were formed according to the following enamel treatments: G1- 20% H2 O2 (1 application); G2- 20% H2 O2 (2 applications); G3- 38% H2 O2 (1 application); G4- 38% H2 O2 (2 applications); G5- 38% H2 O2 (3 applications); and G6- control (no treatment). In G1 and G2, the bleaching gel was left in contact with the enamel surface for 45 min in each application. However, in G3, G4, and G5 the bleaching gel was applied for only 10 min per application. After the last application, the extracts were collected and applied on previously cultured cells (30.000 cells/cm2 ) for 24 h. Cell metabolism was evaluated by the MTT assay and cell morphology was analysed by scanning electron microscopy. Cell metabolism decreased by 96.29%; 96.11%; 96.42%; 95.62%; and 97.18% in G1, G2, G3, G4, and G5, respectively. All treated groups differed significantly from non-treated control group (G6) (p < 0.05). However, the difference in cell metabolism among treated groups was not significant statistically. In addition, significant morphological cell alterations were observed in all treated groups. Under the tested experimental conditions, the extracts collected after both tooth bleaching techniques evaluated in this study caused severe toxic effects on cultured odontoblast-like cell MDPC-23.

Efeito de um gel de peróxido de carbamida a 10% sobre a resistência de união de restaurações adesivas à dentina

The present study aimed to analyze the effects of tooth bleaching with 10% carbamide peroxide (CP) gel on the bond strength of resin composite restorations to dentin. Material and Methods: Twenty cavities were prepared on the buccal surface of bovine teeth. After acid etching and application of bonding agent on dentin and enamel, the cavities were restored with composite resin. The specimens were divided into groups according to treatment on the surface of enamel / restoration: G1 - control (no treatment) and G2 (10% PC gel application for 8h/day during 14 days). After this period, the teeth were cut to produce beams with 0.81 mm2 cross-sectional area, which were subjected to microtensile test. The fractures were examined with a stereomicroscope and classified as cohesive in resin or dentin, adhesive, or mixed. Results: The statistical analysis (ANOVA / χ2) revealed that the factor treatment interfered with the bond strength, which was significantly higher for specimens of G2 (p <0.05). Adhesive fractures occurred in most of specimens of both groups with values ranging from 48.3% to 75%. Mixed fractures were the second more frequent in G1 and cohesive resin failure in G2. Conclusion: It was concluded that tooth bleaching with 10% of PC increased the bond strength of adhesive restorations to dentin.

Citotoxicidade transamelodentinária de uma fita clareadora com 10% de peróxido de hidrogênio sobre células de linhagem odontoblástica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efetividade e sensibilidade com uso de géis clareadores experimental e comercial à base de peróxido de carbamida

Pós-graduação em Odontologia Restauradora - ICT

Análise histológica e imunoistoquímica do tecido pulpar de ratos Wistar submetidos a procedimento clareador com duas concentrações de peróxido de hidrogênio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modificação de amido de mandioca com peróxido de hidrogênio e ácido lático em diferentes processos de secagem

The oxidized cassava starch is widely used in various industrial sectors, the major textile, paper and more recently by the food industry due to its characteristics, such as expansion property to baking. This study aimed to develop a modification of cassava starch by reaction with hydrogen peroxide and lactic acid, with two different types of drying, in the sun and in oven dried, in order to develop the expansion with increase of carboxyl groups and to evaluate differences between the types of drying and compare them with Expandex® starch and pre-gelatinized. The results indicated an increase in the rate of expansion of the modified starch dry in the sun, however the results of the content carboxylic groups haven't indicated the relationship with their rate expansion.

Eficiência de um sistema de desinfecção solar de águas residuárias domésticas com adição de diferentes doses de peróxido de hidrogênio

Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

Ação de enxaguatórios clareadores e sua associação ao clareamento caseiro com peróxido de carbamida

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência do peróxido e do uso de diferentes substâncias de combate à dor na inflamação e na expressão de neuropeptídeos pró-inflamatórios após o tratamento clareador

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)