Protective effect of phytochemicals on the triclosan-induced DNA damag

Aim: Triclosan, an antibacterial and antifungal agent, is widely used in several consumer products, including soaps, toothpaste and surgical cleaning treatments. The present study aimed to examine oxidative DNA damage in rat lymphocytes and its protection by phytochemicals via comet assay. Methodology: DNA damage of rat lymphocytes induced by triclosan was measured by the olive tail moment in the comet assay. Following the addition of N-acetylcysteine, curcumin, berberine and resveratrol, the reduction of DNA damage was observed by using comet assay. Results: The increased olive tail moment induced by triclosan was significantly reduced upon treating N-acetylcysteine and three phytochemicals, such as curcumin, berberine and resveratrol. Notably, the oxidative DNA damage by triclosan was dramatically suppressed by curcumin close to the control value, which means almost complete protection in vitro. Interpretation: These results suggest that in vitro suppressive effect of curcumin, berberine and resveratrol against DNA damage by triclosan might be due to their antioxidative properties, and could be utilized for developing a reducing agent for triclosan toxicity. Key words: These results suggest that in vitro suppressive effect of curcumin, berberine and resveratrol against DNA damage by triclosan might be due to their antioxidative properties, and could be utilized for developing a reducing agent for triclosan toxicity.

Effect of 4-(N,N-dimethylamino)phenethyl Alcohol on Degree of Conversion and Cytotoxicity of Photo-Polymerized CQ-Based Resin Composites

The aim of this study was to evaluate the degree of conversion (DC) and the cytotoxicity of photo-cured experimental resin composites containing 4-(N,N-dimethylamino)phenethyl alcohol (DMPOH) combined to the camphorquinone (CQ) compared with ethylamine benzoate (EDAB). The resin composites were mechanically blended using 35 wt% of an organic matrix and 65 wt% of filler loading. To this matrix was added 0.2 wt% of CQ and 0.2 wt% of one of the reducing agents tested. 5x1 mm samples (n=5) were previously submitted to DC measurement and then pre-immersed in complete culture medium without 10% (v/v) bovine serum for 1 h or 24 h at 37 °C in a humidifier incubator with 5% CO2 and 95% humidity to evaluate the cytotoxic effects of experimental resin composites using the MTT assay on immortalized human keratinocytes cells. As a result of absence of normal distribution, the statistical analysis was performed using the nonparametric Kruskal-Wallis to evaluate the cytotoxicity and one-way analysis of variance to evaluate the DC. For multiple comparisons, cytotoxicity statistical analyses were submitted to Student-Newman-Keuls and DC analysis to Tukey's HSD post-hoc test (=0.05). No significant differences were found between the DC of DMPOH (49.9%) and EDAB (50.7%). 1 h outcomes showed no significant difference of the cell viability between EDAB (99.26%), DMPOH (94.85%) and the control group (100%). After 24 h no significant difference were found between EDAB (48.44%) and DMPOH (38.06%), but significant difference was found compared with the control group (p>0.05). DMPOH presented similar DC and cytotoxicity compared with EDAB when associated with CQ.

O objetivo deste estudo foi avaliar o grau de conversão (GC) e a citotoxicidade de resinas compostas experimentais utilizando o álcool 4-(N,N-dimetilamino) fenil etílico (DMPOH) associado à canforoquinona (CQ) como sistema fotoiniciador (SF) comparado à versão comercial utilizando o benzoato de etilamina (EDAB). Para tanto, as resinas compostas experimentais foram mecanicamente misturadas utilizando (em peso): 35% de matriz orgânica e 65% em peso de partículas de carga. Posteriormente, foram adicionados 0,2% de CQ e 0,2% de um dos agentes redutores testados. Amostras de 5 x 1 mm (n=5) foram previamentes submetidas à análise de GC e posteriormente, esterilizadas e colocadas no meio de cultura completo sem soro fetal bovino estéril por 1 h ou 24 h a 37 °C em encubadora com 5% de CO2 and 95% de umidade para avaliar os efeitos citotóxicos das resinas compostas experimentais utilizando o método MTT emcélulas células humanas imortalizadas de queratinócitos. Os dados de citotoxicidade foram submetidos à análise estatística de Kruskal-Wallis e de GC à análise de variância com um fator. Em virtude da ausência de normalidade, a análise estatística da citotoxicidade foi realizada utilizando-se o teste não-paramétrico de Kruskal-Wallis. Para o GC, os dados foram submetidos à análise de variaância de 1 fator. Posteriormente para múltiplas comparações, os dados de citotoxicidade foram submetidos ao teste Student-Newman-Keuls e o GC ao teste de Tukey's HSD post-hoc (=0.05). Não foi observada diferença estatística entre o GC de DMPOH (49,9%) e EDAB (50,7%). Para os resultados de 1 h não houve diferença na viabilidade celular entre EDAB (99,26%), DMPOH (94,85%) e o grupo controle (100%). Após 24 h, nenhuma diferença estatística foi encontrada entre EDAB (48,44%) e DMPOH (38,06%), entretanto, diferença significativa foi encontrada em relação ao grupo controle (p>0,05). O DMPOH apresentou GC e citotoxicidade semelhante à EDAB quando associado à CQ.

Diffusing effect of DTT and 2-ME during SDS-PAGE electrophoresis / 医学研究生学报

Objective: Dithiothreitol(DTT) and ?-Mercaptoethanol(2-ME) are important reducing agents for SDS-PAGE.This study is to observe the diffusing effect of DTT and 2-ME during electrophoresis,and to find a way of avoiding this effect.Methods: We placed protein samples containing reducing agents and non-reduced protein samples separately in the sample wells at intervals for SDS-PAGE electrophoresis,and determined whether or not the electrophoretic lanes of the non-reduced samples were interfered by the adjacent lanes.Results: DTT and 2-ME diffused to the neighboring lane,so that the non-reduced samples were reduced partially.The spreading effect was positively correlated with the content of the reducing agent.Conclusion: DTT and 2-ME have a diffusing effect during SDS-PAGE electrophoresis.In separating the reduced and non-reduced proteins in the same gel at the same time,at least a blank lane should be set up in between them in order to avoid the diffusing effect.

EFFECT OF DITHIOTHREITOL ON Ca<SUP>2+</SUP>-ATPase ACTIVITY OF SARCOPLASMIC RETICULUM IN RAT SKELETAL MUSCLE AFTER HIGH-INTENSITY EXERCISE / 体力科学

Although the precise mechanisms underlying the dysfunction of sarcoplasmic reticulum (SR) that occurs during skeletal muscle fatigue remain obscure, it has been hypothesized that it may be attributable to oxidation of critical sulfhydryl groups residing in SR Ca<SUP>2+</SUP>-ATPase protein by endogenously produced reactive oxygen species. In order to test this hypothesis, SR Ca<SUP>2+</SUP>-ATPase activities in the absence or presence of the disulfide reducing agent, dithiothreitol (DTT), were examined in muscle homogenates of the soleus muscles (SQL) and the superficial portions of the vastus lateralis muscles (VS) from the rat subjected to exhaustive running at 50 m/min on a 10% grade. Immediately after exercise, the catalytic activity of SR Ca<SUP>2+</SUP>-ATPase was significantly depressed in VS, but not in SQL. The loss of SR Ca<SUP>2+</SUP>-ATPase activity observed in VS was fully recovered after treatment with DTT (1 mM) . These recovery effects of a potent disulfide reducing agent suggest that important proteins of SR Ca<SUP>2+</SUP>-ATPase may be oxidized during high-intensity exercise and that the onset of muscular fatigue may be delayed by the improved function of the cellular antioxidant