Antimicrobial action and cytotoxicity of hypochlorous acid obtained from an innovative electrolytic device - An in vitro study.

OBJECTIVE: This study evaluated the antimicrobial effect and cytotoxicity of hypochlorous acid(HClO) obtained from an innovative electrolytic device. DESIGN: The root canals of fifty extracted human teeth were inoculated with Enterococcus faecalis and divided into 5 groups (n = 10): DW (control); 2% chlorhexidine gel(CHX); 2.5% sodium hypochlorite(NaOCl); 250 ppm HClO and 500 ppm HClO. The counting of colony forming units evaluated the decontamination potential of each group. Cytotoxicity was evaluated after inoculation of tested protocols in fibroblastic cells for 3 min, calculating the cell viability. Specific statistical analysis was performed (α = 5%). RESULTS: The highest bacterial reduction was observed in experimental groups, with no statistical differences from each other (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences from each other (p < 0.05). CONCLUSIONS: It could be concluded that HClO presented high antimicrobial activity and low cytotoxicity at both tested concentrations.

Antimicrobial action, cytotoxicity and erosive potential of hypochlorous acid obtained from an electrolytic device compared with sodium hypochlorite.

OBJECTIVES: This study aimed to compare the antimicrobial action, cytotoxicity, cleaning ability, and erosion of dentine of hypochlorous acid (HClO) obtained from an electrolytic device at two different concentrations (Dentaqua) and three concentrations of sodium hypochlorite (NaOCl). METHODS: Microbiological test-The root canals of sixty single-rooted extracted human teeth were inoculated with Enterococcus faecalis and divided into 6 groups (n = 10), according to decontamination protocol: DW (control); 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl; 250 ppm HClO and 500 ppm HClO. The colony-forming units were counted to evaluate the decontamination potential of each group, calculating the reduction in bacterial percentage. Cytotoxicity test-Cytotoxicity was evaluated after inoculation of the same tested protocols in fibroblastic cells for 3 min, calculating the cell viability percentages. Specifical statistical analysis was performed (α = 5%). Cleaning ability and erosion-Fifty-six single-rooted bovine lower incisors were divided into seven groups of 8 roots each, being the test groups 1% NaOCl; 2.5% NaOCl; 5,25% NaOCl; 250 ppm HClO and 500 ppm HClO, and a negative and positive control. Negative control was not contaminated, and the other groups were inoculated with Enterococcus faecalis. SEM images were ranked as from the cleanest to the least clean. Erosion was also assessed, being ranked from the least to the most eroded dentine. RESULTS: The highest bacterial reduction was observed in experimental groups, with no statistical differences between them (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences between them (p < 0.05). 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl and 500 ppm HClO displayed the cleanest areas. All sodium hypochlorite groups displayed erosion with higher ranks with greater concentration, while hypochlorous acid did not display any erosion regardless the concentration. CONCLUSIONS: It is possible to conclude that HClO obtained from an electrolytic device presented high antimicrobial activity and low cytotoxicity in both tested concentrations. 500 ppm HClO did not display erosion and showed great cleaning ability. CLINICAL RELEVANCE: The use of 500 ppm hypochlorous acid may reduce unfavorable behavior of sodium hypochlorite whilst maintaining its antimicrobial action.

Atorvastatin Prevents Cognitive Deficits Induced by Intracerebroventricular Amyloid-ß1-40 Administration in Mice: Involvement of Glutamatergic and Antioxidant Systems.

Deposition of amyloid-ß (Aß) peptides into specific encephalic structures has been pointed as an important event related to Alzheimer's disease pathogenesis and associated with activation of glial cells, neuroinflammation, oxidative responses, and cognitive deficits. Aß-induced pro-oxidative damage may regulate the activity of glutamate transporters, leading to reduced glutamate uptake and, as a consequence, excitotoxic events. Herein, we evaluated the effects of the pretreatment of atorvastatin, a HMG-CoA reductase inhibitor, on behavioral and biochemical alterations induced by a single intracerebroventricular (i.c.v.) injection of aggregated Aß1-40 in mice. Atorvastatin (10 mg/kg/day, p.o.) was administered through seven consecutive days before Aß1-40 administration. Aß1-40 caused significant cognitive impairment in the object-place recognition task (2 weeks after the i.c.v. injection) and this phenomenon was abolished by atorvastatin pretreatment. Ex vivo evaluation of glutamate uptake into hippocampal and cerebral cortices slices showed atorvastatin, and Aß1-40 decreased hippocampal and cortical Na(+)-dependent glutamate uptake. However, Aß1-40 increased Na(+)-independent glutamate uptake and it was prevented by atorvastatin in prefrontal cortex slices. Moreover, Aß1-40 treatment significantly increased the cerebrocortical activities of glutathione reductase and glutathione peroxidase and these events were blunted by atorvastatin pretreatment. Reduced or oxidized glutathione levels were not altered by Aß1-40 and/or atorvastatin treatment. These results extend the notion of the protective action of atorvastatin against neuronal toxicity induced by Aß1-40 demonstrating that a pretreatment with atorvastatin prevents the spatial learning and memory deficits induced by Aß in rodents and promotes changes in glutamatergic and antioxidant systems mainly in prefrontal cortex.

Oxidative stress-mediated inhibition of brain creatine kinase activity by methylmercury.

Methylmercury (MeHg), a potent neurotoxicant, easily passes through the blood-brain barrier and accumulates in brain causing severe irreversible damage. However, the underlying neurotoxic mechanisms elicited by MeHg are still not completed defined. In this study, we aimed to investigate the in vitro toxic effects elicited by crescent concentrations (0-1500 microM) of MeHg on creatine kinase (CK) activity, thiol content (NPSH) and protein carbonyl content (PCC) in mouse brain preparations. In addition, CK activity, MTT reduction and DCFH-DA oxidation (reactive oxygen species (ROS) formation) were also measured in C6 glioma cell linage. CK activity was severely reduced by MeHg treatment in mouse brain preparations. This inhibitory effect was positively correlated to the MeHg-induced reduction of NPSH levels and increment in PCC. Moreover, the positive correlation between brain CK activity and NPSH levels was observed at either 15 or 60 min of MeHg pre-incubation. In addition, MeHg-treated C6 cells showed also a significant inhibition of CK activity at MeHg concentrations, as low as, 50 microM in parallel to reduced mitochondrial function and increased ROS production. Taking together, these data demonstrate that MeHg severely affects CK activity, an essential enzyme for brain energy buffering to maintain cellular energy homeostasis. This effect appears to be mediated by oxidation of thiol groups that might cause subsequent oxidative stress.