RESUMO
OBJECTIVE: This study evaluated the influence of smoking on the oral cells genotoxicity before and after at-home bleaching using 22% carbamide peroxide (CP). MATERIALS AND METHODS: This is a prospective observational analytics cohort study which evaluated nonsmokers (NS; n = 24) and smokers (S; n = 16) patients. At-home bleaching was performed using 22% CP gel in individual trays for 1 h per day for 14 days in both groups. Scrapped cells from marginal gums were collected before the bleaching treatment (D0-baseline) and 1 day (D1), 15 days (D15), and 1 month (D30) after its finishing. Cells were stained with Giemsa 10%, and the micronucleus (MN) and metanuclear alterations (MA) were counted by a trained operator in 1000 cells per patient. The collections and data analysis occurred blindly. Data was analyzed by Kruskal-Wallis, Dunn, and Mann-Whitney test (α = 0.05). RESULTS: MN frequency was not influenced by smoking or bleaching. An increase of MA was observed between D0 and D30 for both groups (p < 0.001); however, no statistical difference was found between NS and S (p > 0.05) in the evaluation times. CONCLUSION: Smoking associated with 22% carbamide peroxide gel for at-home bleaching does not show genotoxic potential analyzed by the MN counts. However, a significant increase of MA was found for smokers and nonsmokers. CLINICAL RELEVANCE: Despite of the increase in MA, smoking associated with 22% CP peroxide at-home bleaching showed no important genotoxic potential (MN) for oral cells. Therefore, at-home bleaching treatment is safe for nonsmokers and smokers even with a high carbamide peroxide concentration of 22%.
Assuntos
Clareadores Dentários , Clareamento Dental , Peróxido de Carbamida , Estudos de Coortes , Dano ao DNA , Humanos , Peróxido de Hidrogênio , Peróxidos/toxicidade , Fumar/efeitos adversos , Clareamento Dental/efeitos adversos , Clareadores Dentários/toxicidade , UreiaRESUMO
Trypanosoma cruzi is exposed during its life to exogenous and endogenous oxidative stress, leading to damage of several macromolecules such as DNA. There are many DNA repair pathways in the nucleus and mitochondria (kinetoplast), where specific protein complexes detect and eliminate damage to DNA. One group of these proteins is the DNA polymerases. In particular, Tc DNA polymerase ß participates in kinetoplast DNA replication and repair. However, the mechanisms which control its expression under oxidative stress are still unknown. Here we describe the effect of oxidative stress on the expression and function of Tc DNA polymerase ß To this end parasite cells (epimastigotes and trypomastigotes) were exposed to peroxide during short periods of time. Tc DNA polymerase ß which was associated physically with kinetoplast DNA, showed increased protein levels in response to peroxide damage in both parasite forms analyzed. Two forms of DNA polymerase ß were identified and overexpressed after peroxide treatment. One of them was phosphorylated and active in DNA synthesis after renaturation on polyacrylamide electrophoresis gel. This phosphorylated form showed 3-4-fold increase in both parasite forms. Our findings indicate that these increments in protein levels are not under transcriptional control because the level of Tc DNA polymerase ß mRNA is maintained or slightly decreased during the exposure to oxidative stress. We propose a mechanism where a DNA repair pathway activates a cascade leading to the increment of expression and phosphorylation of Tc DNA polymerase ß in response to oxidative damage, which is discussed in the context of what is known in other trypanosomes which lack transcriptional control.
Assuntos
DNA Polimerase beta/biossíntese , Estresse Oxidativo , Processamento de Proteína Pós-Traducional , Proteínas de Protozoários/biossíntese , Trypanosoma cruzi/enzimologia , Trypanosoma cruzi/fisiologia , Northern Blotting , Western Blotting , DNA Polimerase beta/metabolismo , Eletroforese em Gel de Poliacrilamida , Perfilação da Expressão Gênica , Peróxidos/toxicidade , Fosforilação , Proteoma/análise , Proteínas de Protozoários/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Trypanosoma cruzi/efeitos dos fármacosRESUMO
OBJECTIVES: The aim of this study was to evaluate the cytotoxicity and the influence of bleaching agents on immunologically cell surface antigens of murine macrophages in vitro. MATERIALS AND METHODS: RAW 264.7 cells were exposed to bleaching gel extracts (40% hydrogen peroxide or 20% carbamide peroxide) and different H2O2 concentrations after 1 and 24-h exposure periods and 1-h exposure and 23-h recovery. Tests were performed with and without N-acetyl cysteine (NAC) and buthionine sulfoximine (BSO). Cell viability was determined by MTT assay. The expression of surface markers CD14, CD40, and CD54 with and without LPS stimulation was detected by flow cytometry, while the production of TNF-α was measured by ELISA. Statistical analysis was performed using the Mann-Whitney U test (α = 0.05). RESULTS: Extracts of bleaching agents were cytotoxic for cells after a 1-h exposure; cells could not recover after 24 h. This effect can be mitigated by the antioxidant NAC and increased by BSO, an inhibitor of glutathione (GSH) synthesis. LPS stimulated expression of all surface markers and TNF-α production. Exposure to bleaching agent extracts and H2O2 leads to a reduction of TNF-α, CD14, and CD40 expression, while the expression of CD54 was upregulated at non-cytotoxic concentrations. Whereas NAC reduced this effect, it was increased in the presence of BSO. CONCLUSIONS: Extracts of bleaching agents were irreversibly cytotoxic to macrophages after a 1-h exposure. Only the expression of CD54 was upregulated. The reactions are mediated by the non-enzymatic antioxidant GSH. CLINICAL RELEVANCE: The addition of an antioxidant can downregulate unfavorable effects of dental bleaching.
Assuntos
Antígenos de Superfície/efeitos dos fármacos , Clareadores/toxicidade , Peróxido de Hidrogênio/toxicidade , Peróxidos/toxicidade , Ureia/análogos & derivados , Acetilcisteína/farmacologia , Animais , Antígenos de Superfície/imunologia , Butionina Sulfoximina/farmacologia , Peróxido de Carbamida , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Macrófagos/efeitos dos fármacos , Camundongos , Clareamento Dental , Fator de Necrose Tumoral alfa/imunologia , Ureia/toxicidadeRESUMO
OBJECTIVE:: This study evaluated the inflammatory responses of human dental pulp after the use of two bleaching techniques. MATERIAL AND METHODS:: Pulp samples were collected from human third molars extracted for orthodontic reasons and divided into three groups: control - no tooth bleaching (CG) (n=7); at-home bleaching with 15% carbamide peroxide (AH) (n = 10), and in-office bleaching with 38% hydrogen peroxide (IO) (n=12). Pulps were removed and stained with hematoxylin-eosin for microscopic analysis of inflammation intensity, collagen degradation, and pulp tissue organization. Immunohistochemistry was used to detect mast cells (tryptase+), blood vessels (CD31+), and macrophages (CD68+). Chi-square, Kruskal-Wallis, and Mann Whitney tests were used for statistical analysis. The level of significance was set at p<.05. RESULTS:: The inflammation intensity and the number of macrophages were significantly greater in IO than in AH and CG (p<0.05). The results of CD31+ (blood vessels per mm2) were similar in CG (61.39±20.03), AH (52.29±27.62), and IO (57.43±8.69) groups (p>0.05). No mast cells were found in the pulp samples analyzed. CONCLUSION:: In-office bleaching with 38% hydrogen peroxide resulted in more intense inflammation, higher macrophages migration, and greater pulp damage then at-home bleaching with 15% carbamide peroxide, however, these bleaching techniques did not induce migration of mast cells and increased the number of blood vessels.
Assuntos
Polpa Dentária/efeitos dos fármacos , Pulpite/induzido quimicamente , Clareadores Dentários/toxicidade , Clareamento Dental/efeitos adversos , Antígenos CD , Antígenos de Diferenciação Mielomonocítica , Vasos Sanguíneos/efeitos dos fármacos , Vasos Sanguíneos/patologia , Peróxido de Carbamida , Contagem de Células , Colágeno/efeitos dos fármacos , Polpa Dentária/patologia , Humanos , Peróxido de Hidrogênio/toxicidade , Imuno-Histoquímica , Peróxidos/toxicidade , Molécula-1 de Adesão Celular Endotelial a Plaquetas , Pulpite/patologia , Distribuição Aleatória , Estatísticas não Paramétricas , Fatores de Tempo , Clareamento Dental/métodos , Ureia/análogos & derivados , Ureia/toxicidadeRESUMO
ABSTRACT Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp. Objective: This study evaluated the inflammatory responses of human dental pulp after the use of two bleaching techniques. Material and Methods: Pulp samples were collected from human third molars extracted for orthodontic reasons and divided into three groups: control - no tooth bleaching (CG) (n=7); at-home bleaching with 15% carbamide peroxide (AH) (n = 10), and in-office bleaching with 38% hydrogen peroxide (IO) (n=12). Pulps were removed and stained with hematoxylin-eosin for microscopic analysis of inflammation intensity, collagen degradation, and pulp tissue organization. Immunohistochemistry was used to detect mast cells (tryptase+), blood vessels (CD31+), and macrophages (CD68+). Chi-square, Kruskal-Wallis, and Mann Whitney tests were used for statistical analysis. The level of significance was set at p<.05. Results: The inflammation intensity and the number of macrophages were significantly greater in IO than in AH and CG (p<0.05). The results of CD31+ (blood vessels per mm2) were similar in CG (61.39±20.03), AH (52.29±27.62), and IO (57.43±8.69) groups (p>0.05). No mast cells were found in the pulp samples analyzed. Conclusion: In-office bleaching with 38% hydrogen peroxide resulted in more intense inflammation, higher macrophages migration, and greater pulp damage then at-home bleaching with 15% carbamide peroxide, however, these bleaching techniques did not induce migration of mast cells and increased the number of blood vessels.
Assuntos
Humanos , Pulpite/induzido quimicamente , Clareamento Dental/efeitos adversos , Polpa Dentária/efeitos dos fármacos , Clareadores Dentários/toxicidade , Peróxidos/toxicidade , Pulpite/patologia , Fatores de Tempo , Clareamento Dental/métodos , Ureia/análogos & derivados , Ureia/toxicidade , Vasos Sanguíneos/efeitos dos fármacos , Vasos Sanguíneos/patologia , Imuno-Histoquímica , Antígenos de Diferenciação Mielomonocítica , Distribuição Aleatória , Antígenos CD , Contagem de Células , Colágeno/efeitos dos fármacos , Estatísticas não Paramétricas , Molécula-1 de Adesão Celular Endotelial a Plaquetas , Polpa Dentária/patologia , Peróxido de Hidrogênio/toxicidadeRESUMO
O clareamento dental é um dos tratamentos mais realizados nos consultórios odontológicos a fim de melhorar a aparência do sorriso. O procedimento consiste na aplicação de um gel clareador, a base de peróxido de carbamida ou de hidrogênio, sobre os dentes a serem clareados. A sensibilidade dentária é o efeito adverso mais frequentemente relatado no clareamento dentário e é a principal causa de desmotivação dos pacientes. O mecanismo pelo qual se produz a sensibilidade após clareamento dentário ainda não foi completamente elucidado; no entanto, parece estar associado à rápida difusão dos agentes clareadores através do esmalte e dentina que, devido ao seu grau de citotoxicidade, podem agir agredindo as células pulpares, causando sensibilidade. O objetivo deste estudo foi avaliar a biocompatibilidade de nanopartícula de hidroxiapatita adicionada ao gel clareador peróxido de carbamida 16% com flúor e sem flúor e, para tanto, foram realizados testes de citotoxidade empregando MTT. Como resultados verificou-se que as nanopartículas de hidroxiapatita, quando comparadas aos géis de peróxido de carbamida a 16% com e sem flúor, foram as menos citotóxicas (p< 0.05). As diluições citotóxicas convertidas para 70% das amostras testadas também foram comparadas através do teste de Anova com tukey. Foi possível observar que as partículas de nanoHap quando adicionadas nos géis de clareamento com e sem flúor reduziu significativamento a citotoxidade. Concluímos que o novo material proposto nesta investigação apresenta melhor biocompatibilidade do que o gel sem hidroxiapatita, acompanhado da redução da citotoxidade, tais aspectos sugerem que as nanopartículas de hidroxiapatita podem ter aplicações clínicas futuras em tecidos mineralizados em procedimentos de clareamento dental, contribuindo para a redução da sensibilidade dentária.
The dental bleaching is one of the most procedures performed at dental offices to improve the appearance of the smile. The procedure consists of the application of a bleching gel, based on carbamide peroxide or hydrogen over the teeth to be whitened. Tooth sensibility is the frequently reported adverse effect on tooth whitening and is the leading cause of demotivation by the patients. The mechanism that provides the sensibility after tooth whitening has not already been fully elucidated; however, it appears to be associated with the rapid diffusion of bleaching agents through the enamel and dentin that, because of their degree of cytotoxicity, may act attacking pulp cells, causing the sensibility. The aim of this study was to evaluate the biocompatibility of hydroxyapatite nanoparticles added to whitening gel of 16% carbamide peroxide with and without fluoride and, therefore, cytotoxicity tests were performed using MTT. As a result, it was found that the hydroxyapatite nanoparticles, compared to the gels of 16 % carbamide peroxide with and without fluoride, were less cytotoxic (p <0.05). Cytotoxic dilutions converted to 70 % of the tested samples were compared using ANOVA test with Tukey. We concluded that the new material proposed in this research has a better biocompatibility in comparison with the gel without hydroxyapatite, followed by a reduction of cytotoxicity. These aspects suggest that the hydroxyapatite nanoparticles may have clinical future applications in mineralized tissues when dental bleaching procedures are performed, contributing to the reduction of tooth sensitivity. We conclude that the new material proposed in this research has a better biocompatibility of the gel without hydroxyapatite, accompanied by a reduction of cytotoxicity, these aspects suggest that the hydroxyapatite nanoparticles may have future clinical applications in mineralized tissues in dental bleaching procedures, contributing to a reduction tooth sensitivity.
Assuntos
Animais , Camundongos , Peróxidos/toxicidade , Clareamento Dental/efeitos adversos , Ureia/toxicidade , Durapatita/toxicidade , Sensibilidade da Dentina/prevenção & controle , Nanopartículas/toxicidade , Técnicas In Vitro , Teste de Materiais , Técnicas de Cultura de Células , Dessensibilizantes Dentinários/toxicidade , Clareadores Dentários/toxicidade , Clareadores Dentários/farmacologia , Antioxidantes/toxicidadeRESUMO
In order to understand how fungal pathogens can survive inside the host, we must analyze how they evade the fungicidal mechanisms mounted by the host's immune system, such as generation of toxic reactive oxygen species. Studies have shown that infections caused by Sporothrix brasiliensis can be more aggressive than those due to Sporothrix schenckii. Therefore, we propose to analyze and compare the ability of these two pathogenic species to counteract oxidative stress, which, as noted, can be relevant in the host response to infection. We have shown that S. brasiliensis is more resistant to different oxidants, such as H2O2 and menadione, when compared with S. schenckii. Furthermore, our results suggest that the molecular mechanisms by which Sporothrix spp. AP-1 like transcription factors are regulated probably differs from the one seen in other fungal pathogens. Interestingly, comparison between sequences of SbHog1 and SsHog1 stress activated protein kinases suggest that S. brasiliensis Hog1 display mutations that could account for the differences seen in stress sensitivities of these two species. In summary, this is the first study to our knowledge to investigate oxidative stress responses of Sporothrix spp. and provided a model that can be employed in vivo to address how these fungal pathogens can surmount the oxidative stress generated by the host.
Assuntos
Proteínas Quinases Ativadas por Mitógeno/genética , Peróxidos/toxicidade , Transdução de Sinais , Sporothrix/efeitos dos fármacos , Sporothrix/fisiologia , Estresse Fisiológico , Fator de Transcrição AP-1/genética , Biologia Computacional , Regulação Fúngica da Expressão Gênica , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Mutação de Sentido Incorreto , Estresse Oxidativo , Sporothrix/genética , Fator de Transcrição AP-1/metabolismoRESUMO
The aim of this study was to evaluate the possibility of fluoride solutions applied to enamel to protect pulp cells against the trans-enamel and transdentinal cytotoxicity of a 16% carbamide peroxide (CP) bleaching gel. The CP gel was applied to enamel/dentin discs adapted to aicial pulp chambers (8 h/day) during 1, 7 or 14 days, followed by fluoride (0.05% or 0.2%) application for 1 min. The extracts (culture medium in contact with dentin) were applied to MDPC-23 cells for 1 h, and cell metabolism (MTT assay), alkaline phosphatase (ALP) activity and cell membrane damage (flow cytometry) were analyzed. Knoop microhardness of enamel was also evaluated. Data were analyzed statistically by ANOVA and Kruskal-Wallis tests (α=0.05). For the MTT assay and ALP activity, significant reductions between the control and the bleached groups were observed (p<0.05). No statistically significant difference occurred among bleached groups (p>0.05), regardless of fluoride application or treatment days. Flow cytometry analysis demonstrated 30% of cell membrane damage in all bleached groups. After 14 days of treatment, the fluoride-treated enamel presented significantly higher microhardness values than the bleached-only group (p<0.05). It was concluded that, regardless of the increase in enamel hardness due to the application of fluoride solutions, the treated enamel surface did not prevent the toxic effects caused by the 16% CP gel to odontoblast-like cells.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Polpa Dentária/efeitos dos fármacos , Fluoretos/farmacologia , Peróxidos/toxicidade , Substâncias Protetoras/farmacologia , Clareadores Dentários/toxicidade , Ureia/análogos & derivados , Fosfatase Alcalina/efeitos dos fármacos , Animais , Peróxido de Carbamida , Bovinos , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Corantes , Polpa Dentária/citologia , Cavidade Pulpar/efeitos dos fármacos , Dentina/efeitos dos fármacos , Dureza , Odontoblastos/efeitos dos fármacos , Odontoblastos/metabolismo , Propídio , Succinato Desidrogenase/efeitos dos fármacos , Fatores de Tempo , Ureia/toxicidadeRESUMO
The aim of this study was to evaluate the possibility of fluoride solutions applied to enamel to protect pulp cells against the trans-enamel and transdentinal cytotoxicity of a 16% carbamide peroxide (CP) bleaching gel. The CP gel was applied to enamel/dentin discs adapted to aicial pulp chambers (8 h/day) during 1, 7 or 14 days, followed by fluoride (0.05% or 0.2%) application for 1 min. The extracts (culture medium in contact with dentin) were applied to MDPC-23 cells for 1 h, and cell metabolism (MTT assay), alkaline phosphatase (ALP) activity and cell membrane damage (flow cytometry) were analyzed. Knoop microhardness of enamel was also evaluated. Data were analyzed statistically by ANOVA and Kruskal-Wallis tests (α=0.05). For the MTT assay and ALP activity, significant reductions between the control and the bleached groups were observed (p<0.05). No statistically significant difference occurred among bleached groups (p>0.05), regardless of fluoride application or treatment days. Flow cytometry analysis demonstrated 30% of cell membrane damage in all bleached groups. After 14 days of treatment, the fluoride-treated enamel presented significantly higher microhardness values than the bleached-only group (p<0.05). It was concluded that, regardless of the increase in enamel hardness due to the application of fluoride solutions, the treated enamel surface did not prevent the toxic effects caused by the 16% CP gel to odontoblast-like cells.
Resumo O objetivo do presente estudo foi avaliar o possível efeito protetor de soluções fluoretadas aplicadas sobre o esmalte dentário frente à citotoxicidade trans-amelodentinária de um gel clareador com 16% de peróxido de carbamida (PC). O gel de PC foi aplicado sobre discos de esmalte/dentina adaptados a câmaras pulpares aiciais (8 h/dia) durante períodos de 1, 7 ou 14 dias, seguido de aplicação de soluções fluoretadas (0,05% ou 0,2%) durante 1 min. Os extratos (meio de cultura em contato com a dentina) foram aplicados sobre células MDPC-23 durante 1 h, seguido de análise do metabolismo celular (teste do MTT), atividade de fosfatase alcalina (ALP) e danos à membrana celular (citometria de fluxo). A microdureza Knoop do esmalte dental foi avaliada. Os dados foram analisados pelos testes de ANOVA e Kruskal-Wallis. Para o teste do MTT e atividade de ALP, redução significante entre os grupos controle e clareados foram observados (p<0,05). Nenhuma diferença entre os grupos clareados foi observada (p>0,05), independente da aplicação das soluções fluoretadas ou tempo de tratamento. A análise por citometria de fluxo demonstrou lesão à membrana celular em torno de 30% para todos os grupos clareados. Após 14 dias de tratamento, os espécimes clareados e fluoretados apresentaram aumento significante na microdureza do esmalte (p<0,05). Pôde-se concluir que apesar do aumento na dureza do esmalte decorrente da aplicação das soluções fluoretadas, este tratamento não preveniu os efeitos tóxicos causados pelo gel com 16% de PC sobre as células odontoblastóides. .
Assuntos
Animais , Bovinos , Esmalte Dentário/efeitos dos fármacos , Polpa Dentária/efeitos dos fármacos , Fluoretos/farmacologia , Peróxidos/toxicidade , Substâncias Protetoras/farmacologia , Clareadores Dentários/toxicidade , Ureia/análogos & derivados , Fosfatase Alcalina/efeitos dos fármacos , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Corantes , Cavidade Pulpar/efeitos dos fármacos , Polpa Dentária/citologia , Dentina/efeitos dos fármacos , Dureza , Odontoblastos/efeitos dos fármacos , Odontoblastos/metabolismo , Propídio , Succinato Desidrogenase/efeitos dos fármacos , Fatores de Tempo , Ureia/toxicidadeRESUMO
BACKGROUND: bleaching has been widely studied, mainly due to the possible undesirable effects that can be caused by this esthetic procedure. The cytotoxicity of the bleaching agents and its components to pulp cells has been demonstrated in several researches. The aim of this study was to evaluate the toxic effects of successive applications of 10% carbamide peroxide (CP) gel on odontoblast-like cells. MATERIALS AND METHODS: Enamel-dentin discs obtained from bovine incisors were adapted to artificial pulp chambers (APCs). The groups were formed as follows: G1: Without treatment (control group); G2: 10% carbamide peroxide, CP (five applications/one per day); G3: 10% CP (one unique application); and G4: 35% hydrogen peroxide, HP (three applications of 15 min each). After treatment, cell metabolism (MTT), alkaline phosphatase (ALP) activity and plasma membrane damage (flow cytometry) were analyzed. RESULTS: Reductions in cell metabolism and alkaline phosphatase activity along with severe damage of the cytoplasmic membrane were noted in G2. In G3, no damage was observed, compared to the control group. Intermediary values of toxicity were obtained after 35% HP application. CONCLUSION: It can be concluded that one application of 10% CP did not cause toxic effects in odontoblast-like cells, but the successive application of this product promoted severe cytotoxic effects. The daily application of the bleaching agents, such as used in the at-home bleaching technique, can increase the damages caused by this treatment to the dental pulp cells.
Assuntos
Odontoblastos/efeitos dos fármacos , Peróxidos/toxicidade , Ureia/análogos & derivados , Fosfatase Alcalina/metabolismo , Peróxido de Carbamida , Linhagem Celular , Humanos , Odontoblastos/enzimologia , Peróxidos/administração & dosagem , Ureia/administração & dosagem , Ureia/toxicidadeRESUMO
OBJECTIVE: The purpose of this study was to evaluate the effect of the bleaching agents on the elastic modulus of bovine demineralized dentin matrix (EMDM). MATERIALS AND METHODS: Eighty-five slices were obtained from 17 bovine teeth. The slices were divided randomly into five experimental groups (n = 17): unbleached control group (CG), 4% hydrogen peroxide (HP4), 4% hydrogen peroxide + 0.05% Ca (HP4 + Ca), 7.5% hydrogen peroxide + ACP (HP7.5) and 10% carbamide peroxide (CP10). The HP4, HP4 + Ca and CP10 groups were treated with the bleaching agents for 8 h/day (14 days), while the samples of HP7.5 group were exposed to bleaching agent for 30 min twice a day (14 days). The CG was kept in 100% humidity. After bleaching treatments, the enamel of the samples was removed and 85 dentin beams (0.5 × 1.7 × 7.0 mm) were prepared. Afterwards, the beams were immersed in 10% phosphoric acid solution (5 h) and rinsed with water (10 min). The beams were tested after 24 h, 7 and 14 days of storage in distilled water, using three-point bend method. Data were statistically analyzed using ANOVA and Fisher's test. RESULTS: All bleaching treatments reduced the EMDM. After 14 days post-bleaching, the EMDM increased for HP4 and HP4+Ca groups. CONCLUSIONS: The use of bleaching agents promoted a decrease in EMDM, which indicates that the bleaching treatment interacts with the dentin organic matrix. The EMDM measurement for the specimens of the 7.5% hydrogen peroxide group that were immersed in water at 14 days post-bleaching did not recover the EMDM values when compared to the control group.
Assuntos
Dentina/efeitos dos fármacos , Clareadores Dentários/toxicidade , Clareamento Dental/efeitos adversos , Análise de Variância , Animais , Peróxido de Carbamida , Bovinos , Distribuição de Qui-Quadrado , Módulo de Elasticidade/efeitos dos fármacos , Dureza/efeitos dos fármacos , Peróxido de Hidrogênio/administração & dosagem , Peróxido de Hidrogênio/toxicidade , Teste de Materiais , Peróxidos/administração & dosagem , Peróxidos/toxicidade , Maleabilidade/efeitos dos fármacos , Distribuição Aleatória , Ureia/administração & dosagem , Ureia/análogos & derivados , Ureia/toxicidadeRESUMO
AIM: To evaluate the transenamel and transdentinal cytotoxicity of bleaching gels based on carbamide peroxide (CP) on odontoblast-like cells after different contact times of the products with enamel. METHODOLOGY: Enamel/dentine discs were obtained from bovine incisors and placed in artificial pulp chambers. Bleaching gels containing 10% or 16% CP were applied for 8 h day(-1) on the enamel side of the discs during periods of 1, 7 or 14 days. Deionized water and artificial saliva served as controls. The extracts (culture medium plus bleaching gel products that diffused through the discs) were collected and applied on previously cultured MDPC-23 cells for 1 h. Cell metabolism was evaluated by the MTT assay, and the data were analysed statistically by one-way anova and Tukey's test (α=0.05). Cell morphology was analysed by SEM. RESULTS: There was no significant difference (P>0.05) between the controls and the groups bleached with 10% CP gel. In the groups bleached with 16% CP gel, however, cell metabolism decreased significantly (P<0.05) by 40.32%, 30.16% and 26.61% at 1, 7 and 14 days, respectively. There was no significant difference (P>0.05) between 1, 7 or 14 applications of the gels for either of the CP concentrations. CONCLUSION: Regardless of the number of applications on an enamel surface, the 10% CP bleaching gel did not cause transenamel and transdentinal cytotoxicity to the MDPC-23 cell cultures. However, diffusion of products from the 16% CP gel through enamel and dentine and cytopathic effects to the pulp cells occurred even after a single application of this product on enamel.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Odontoblastos/efeitos dos fármacos , Peróxidos/toxicidade , Clareadores Dentários/toxicidade , Ureia/análogos & derivados , Análise de Variância , Animais , Peróxido de Carbamida , Bovinos , Células Cultivadas , Permeabilidade do Esmalte Dentário/efeitos dos fármacos , Relação Dose-Resposta a Droga , Géis , Peróxidos/farmacocinética , Estatísticas não Paramétricas , Fatores de Tempo , Clareadores Dentários/farmacocinética , Ureia/farmacocinética , Ureia/toxicidadeRESUMO
OBJECTIVES: The objectives of this study were to evaluate the transdentinal cytotoxicity of 10% and 16% carbamide peroxide gel (CP), as well as the ability of the antioxidant, 10% sodium ascorbate (SA), to protect the odontoblasts in culture. STUDY DESIGN: Human dentin discs of 0.5-mm thickness were obtained and were placed into artificial pulp chambers. MDPC-23 odontoblastlike cells were seeded on pulp surface of the discs and the following groups were established: G1-No Treatment (control), G2-10% SA/6hs, G3-10%/CP6hs, G4-10%SA/6hs+10%CP/6hs, G5-16%CP/6hs, and G6-10%SA/6hs+16%CP/6hs. The cell viability was measured by the MTT assay. RESULTS: In groups where 16% CP was used, decreased cell viability was observed. Conversely, the application of 10% SA on the dentin discs, before the use of the CP, reduced the cytotoxic effects of these products on cells. CONCLUSIONS: The 16% CP cause a significant decrease in MDPC-23 cell viability and 10% SA was able to partially prevent the toxic effects of CP.
Assuntos
Antioxidantes/uso terapêutico , Ácido Ascórbico/uso terapêutico , Dentina/efeitos dos fármacos , Peróxido de Hidrogênio/toxicidade , Oxidantes/toxicidade , Substâncias Protetoras/uso terapêutico , Clareamento Dental , Peróxido de Carbamida , Adesão Celular/efeitos dos fármacos , Técnicas de Cultura de Células , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Corantes , Permeabilidade da Dentina/efeitos dos fármacos , Difusão , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Odontoblastos/efeitos dos fármacos , Peróxidos/toxicidade , Espectrofotometria Ultravioleta , Sais de Tetrazólio , Tiazóis , Fatores de Tempo , Ureia/análogos & derivados , Ureia/toxicidadeRESUMO
Protein tyrosine dimerization and nitration by biologically relevant oxidants usually depend on the intermediate formation of tyrosyl radical ((*)Tyr). In the case of tyrosine oxidation in proteins associated with hydrophobic biocompartments, the participation of unsaturated fatty acids in the process must be considered since they typically constitute preferential targets for the initial oxidative attack. Thus, we postulate that lipid-derived radicals mediate the one-electron oxidation of tyrosine to (*)Tyr, which can afterward react with another (*)Tyr or with nitrogen dioxide ((*)NO(2)) to yield 3,3'-dityrosine or 3-nitrotyrosine within the hydrophobic structure, respectively. To test this hypothesis, we have studied tyrosine oxidation in saturated and unsaturated fatty acid-containing phosphatidylcholine (PC) liposomes with an incorporated hydrophobic tyrosine analogue BTBE (N-t-BOC l-tyrosine tert-butyl ester) and its relationship with lipid peroxidation promoted by three oxidation systems, namely, peroxynitrite, hemin, and 2,2'-azobis (2-amidinopropane) hydrochloride. In all cases, significant tyrosine (BTBE) oxidation was seen in unsaturated PC liposomes, in a way that was largely decreased at low oxygen concentrations. Tyrosine oxidation levels paralleled those of lipid peroxidation (i.e., malondialdehyde and lipid hydroperoxides), lipid-derived radicals and BTBE phenoxyl radicals were simultaneously detected by electron spin resonance spin trapping, supporting an association between the two processes. Indeed, alpha-tocopherol, a known reactant with lipid peroxyl radicals (LOO(*)), inhibited both tyrosine oxidation and lipid peroxidation induced by all three oxidation systems. Moreover, oxidant-stimulated liposomal oxygen consumption was dose dependently inhibited by BTBE but not by its phenylalanine analogue, BPBE (N-t-BOC l-phenylalanine tert-butyl ester), providing direct evidence for the reaction between LOO(*) and the phenol moiety in BTBE, with an estimated second-order rate constant of 4.8 x 10(3) M(-1) s(-1). In summary, the data presented herein demonstrate that LOO(*) mediates tyrosine oxidation processes in hydrophobic biocompartments and provide a new mechanistic insight to understand protein oxidation and nitration in lipoproteins and biomembranes.
Assuntos
Bicamadas Lipídicas/química , Peróxidos/química , Tirosina/química , Espectroscopia de Ressonância de Spin Eletrônica , Hemina/química , Hemina/toxicidade , Peroxidação de Lipídeos , Dióxido de Nitrogênio/química , Dióxido de Nitrogênio/toxicidade , Oxirredução , Peróxidos/toxicidade , Ácido Peroxinitroso/química , Ácido Peroxinitroso/toxicidade , Multimerização Proteica , Tirosina/análogos & derivados , Tirosina/toxicidade , alfa-Tocoferol/farmacologiaRESUMO
AIM: To evaluate the cytotoxicity and genotoxicity of sodium percarbonate (SPC) in comparison with bleaching agents used on discoloured pulpless teeth. METHODOLOGY: The cytotoxicity and genotoxicity of bleaching agents were evaluated both in their pure form as well as at concentrations commonly used in clinical practice. Hydrogen peroxide (HP), carbamide peroxide (CP), sodium perborate (SP) and SPC were diluted in Dulbecco's modified Eagle's medium (DMEM) in series. To evaluate the cytotoxicity, the survival of 3T3/NIH mouse fibroblasts was measured photometrically using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after a 24 h-exposure period. Genotoxicity was indicated by micronuclei (MN) formation, and modification of the normal cell was analysed by light microscopy (400x). Statistical analysis was performed by one-way anova, followed by a multiple-comparison Tukey post hoc test (P < 0.05). RESULTS: All groups exhibited a dose-dependent cytotoxicity. However, CP showed a similar cytotoxic effect when compared with DMEM-untreated control (UC) group. HP and SPC were significantly more cytotoxic than SP. The genotoxicity test showed that SPC and SP had an intermediate rate of MN frequency when compared with the UC group. The mean rate of MN frequency for HP was higher and statistically more significant than for the other groups tested. No difference was observed when CP and UC groups were compared. CONCLUSIONS: Sodium percarbonate showed cytotoxicity and genotoxicity similar to those of the other products tested. However, before SPC is used clinically, studies should be conducted to confirm its safety in vivo.
Assuntos
Carbonatos/toxicidade , Fibroblastos/efeitos dos fármacos , Peróxidos/toxicidade , Clareamento Dental/efeitos adversos , Análise de Variância , Animais , Boratos/toxicidade , Peróxido de Carbamida , Linhagem Celular , Sobrevivência Celular , Cavidade Pulpar/efeitos dos fármacos , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Fibroblastos/citologia , Peróxido de Hidrogênio/toxicidade , Camundongos , Testes para Micronúcleos , Oxidantes/toxicidade , Estatísticas não Paramétricas , Clareamento Dental/métodos , Descoloração de Dente/tratamento farmacológico , Dente não Vital , Testes de Toxicidade , Ureia/análogos & derivados , Ureia/toxicidadeRESUMO
In some countries, leaves of Vitis vinifera grapes have been used for food and for treating many medical disorders. However, there are no studies on the leaves of Vitis labrusca, the main species used for wine and juice production in South America. In this work, the phenolic compounds and antioxidant activity of organic and conventional grape leaves extracts prepared from V. labrusca (var. Bordo) in brain tissues (in vitro model) have been evaluated. Both organic and conventional grape leaves extracts have similar total phenolic content, however, different patterns were observed for the main phenolic compounds of both kinds of leaves. The organic leaves extract showed about 10 times more resveratrol than the conventional one. Both extracts were able to reduce the lipid and protein damages induced by hydrogen peroxide in the brain of rats. This effect was accompanied by the reversion of the hydrogen peroxide-induced alterations in the superoxide dismutase and catalase activities. Negative correlations between lipid and protein damages and the levels of polyphenols were found, suggesting that these compounds contribute directly to the protective effect observed.
Assuntos
Antioxidantes , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/farmacologia , Peróxidos/toxicidade , Fenóis/química , Fenóis/farmacologia , Vitis/química , Animais , Cerebelo/efeitos dos fármacos , Cerebelo/metabolismo , Cerebelo/patologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta/química , Ratos , Ratos Wistar , Resveratrol , Estilbenos/análise , Estilbenos/química , Estilbenos/farmacologia , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Tumoral angiogenesis has been widely studied by histochemical analysis but little has been done regarding morphology of these new vessels. The objective of this study was to perform a qualitative analysis of the angiogenic response to chemical induction with dimethylbenzanthracene (DMBA) and carbamide peroxide of squamous cell carcinoma in pouches of Syrian hamsters after different periods of treatment. Twenty-four Syrian golden hamsters, divided into three groups of eight animals each, had their right jugal pouches treated with a 5% DMBA solution three times a week and a 10% carbamide peroxide two times a week for 55, 70 and 90 days. The left pouch was considered the control. After tumor induction, five animals in each group had their pouches prepared for analysis under scanning electron microscopy and three animals for analysis under light microscopy. The control pouches showed a vascular system composed by few main vessels running parallel to the longest axis of the pouch with some branches. In the pouches submitted to tumor induction, a well-differentiated squamous cell carcinoma was present since 55 days induction in all samples. The new vascular system showed the presence of many tortuous vessels and the majority of them were veins and capillaries. Terminal loops were extremely sinuous adopting a glomerular or corkscrew shape. These tumor vessels are different from normal vessels, presenting irregular diameters, outpouchings and constrictions. Angiogenesis of sprouting and intussusceptive kind could be identified in the tumor pouches, and they were more frequent as the tumor developed.
Assuntos
Carcinoma de Células Escamosas/veterinária , Mucosa Bucal/patologia , Neoplasias Bucais/veterinária , Neovascularização Patológica , 9,10-Dimetil-1,2-benzantraceno/toxicidade , Animais , Peróxido de Carbamida , Carcinoma de Células Escamosas/induzido quimicamente , Carcinoma de Células Escamosas/patologia , Cricetinae , Combinação de Medicamentos , Masculino , Mesocricetus , Microscopia , Microscopia Eletrônica de Varredura , Neoplasias Bucais/induzido quimicamente , Neoplasias Bucais/patologia , Peróxidos/toxicidade , Ureia/análogos & derivados , Ureia/toxicidadeRESUMO
Drug resistance and virulence of Mycobacterium tuberculosis are partially related to the pathogen's antioxidant systems. Peroxide detoxification in this bacterium is achieved by the heme-containing catalase peroxidase and different two-cysteine peroxiredoxins. M. tuberculosis genome also codifies for a putative one-cysteine peroxiredoxin, alkyl hydroperoxide reductase E (MtAhpE). Its expression was previously demonstrated at a transcriptional level, and the crystallographic structure of the recombinant protein was resolved under reduced and oxidized states. Herein, we report that the conformation of MtAhpE changed depending on its single cysteine redox state, as reflected by different tryptophan fluorescence properties and changes in quaternary structure. Dynamics of fluorescence changes, complemented by competition kinetic assays, were used to perform protein functional studies. MtAhpE reduced peroxynitrite 2 orders of magnitude faster than hydrogen peroxide (1.9 x 10(7) M(-1) s(-1) vs 8.2 x 10(4) M(-1) s(-1) at pH 7.4 and 25 degrees C, respectively). The latter also caused cysteine overoxidation to sulfinic acid, but at much slower rate constant (40 M(-1) s(-1)). The pK(a) of the thiol in the reduced enzyme was 5.2, more than one unit lower than that of the sulfenic acid in the oxidized enzyme. The pH profile of hydrogen peroxide-mediated thiol and sulfenic acid oxidations indicated thiolate and sulfenate as the reacting species. The formation of sulfenic acid as well as the catalytic peroxidase activity of MtAhpE was demonstrated using the artificial reducing substrate thionitrobenzoate. Taken together, our results indicate that MtAhpE is a relevant component in the antioxidant repertoire of M. tuberculosis probably involved in peroxide and specially peroxynitrite detoxification.
Assuntos
Cisteína/química , Mycobacterium tuberculosis/enzimologia , Peroxirredoxinas/química , Peroxirredoxinas/metabolismo , Ácidos Sulfênicos/metabolismo , Compostos de Sulfidrila/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Cinética , Mycobacterium tuberculosis/patogenicidade , Oxirredução , Peróxidos/antagonistas & inibidores , Peróxidos/metabolismo , Peróxidos/toxicidade , Ácido Peroxinitroso/metabolismo , Conformação Proteica , Especificidade por Substrato , Ácidos Sulfênicos/química , Compostos de Sulfidrila/química , TermodinâmicaRESUMO
Chenopodium ambrosioides have been used for centuries in the Americas as a popular remedy for parasitic diseases. The essential oil of this plant possesses anthelmintic activity and is still used in some regions to treat parasitosis and leishmaniasis. However, the Chenopodium oil caused also some fatalities, leading to its commercial disuse. In this work, we studied the mechanism of toxicity of the essential oil and its major pure ingredients (carvacrol, caryophyllene oxide, and ascaridole, which was synthesized from alpha-terpinene) with respect to mammalian cells and mitochondria. We observed that all products, but especially caryophyllene oxide, inhibited the mitochondrial electron transport chain. This effect for carvacrol and caryophyllene oxide was mediated via direct complex I inhibition. Without Fe2+, ascaridole was less toxic to mammalian mitochondria than other major ingredients. However, evidence on the formation of carbon-centered radicals in the presence of Fe2+ was obtained by ESR spin-trapping. Furthermore, it was shown that Fe2+ potentiated the toxicity of ascaridole on oxidative phosphorylation of rat liver mitochondria. The increase of the alpha-tocopherol quinone/alpha-tocopherol ratio under these conditions indicated the initiation of lipid peroxidation by Fe2+-mediated ascaridole cleavage. Further ESR spin-trapping experiments demonstrated that in addition to Fe2+, reduced hemin, but not mitochondrial cytochrome c can activate ascaridole, explaining why ascaridole in peritoneal macrophages from BALB/c mice exhibited a higher toxicity than in isolated mitochondria.
Assuntos
Chenopodium ambrosioides/química , Mitocôndrias Hepáticas/efeitos dos fármacos , Monoterpenos/toxicidade , Óleos Voláteis/química , Peróxidos/toxicidade , Sesquiterpenos/toxicidade , Animais , Monoterpenos Cicloexânicos , Cimenos , Espectroscopia de Ressonância de Spin Eletrônica , Peroxidação de Lipídeos , Espectroscopia de Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fosforilação Oxidativa , Sesquiterpenos Policíclicos , Ratos , Ratos Sprague-DawleyRESUMO
Esse trabalho teve como objetivo avaliar o efeito dos clareadores dentais a base de Peróxido de carbamida a 10% (Whiteness Standart a 10% - FGM) e a 16% (Whiteness Standart a 16% - FGM), em macrófagos alveolares de ratos albinos Wistar, pela produção de óxido nítrico e superóxido...
This study proposes to evaluate the effect of the dental bleaching carbamide peroxide at 10% (Whiteness a 10% - FGM) and at 16% (Whiteness a 16% - FGM), in alveolar macrophages from Wistar albine rats, by the production of nitric oxide and superoxide...