Microbicidal and cytotoxic effects of functional water in vitro.

OBJECTIVE: Several kinds of functional water are used in the fields of food hygiene and medicine. The purpose of this study was to evaluate both the disinfection and cytotoxic effects of functional water in comparison with commonly used root canal irrigants such as sodium hypochlorite solution and hydrogen peroxide solution. METHOD AND MATERIALS: Three kinds of functional water were examined: alkaline electrolysis water (AEW), strong acid electrolyzed water (SAEW), and hypochlorous acid water (HAW). The disinfection effect was studied using Enterococcus faecalis and Candida albicans with or without organic substance. Each kind of functional water was applied to samples, and the colony formation was evaluated. The cytotoxic effect was evaluated by mitogenic assay (MTT) and alkaline phosphatase (ALPase) activity in pulp cells. RESULTS: SAEW and HAW showed microbicidal effects in the presence of organic substance, with an effect almost similar to sodium hypochlorite solution. AEW did not show any microbicidal effect. SAEW, AEW, and HAW at 10- and 1,000-times dilution did not inhibit the MTT assay and ALPase activity. The cytotoxicity of SAEW and HAW against pulp cells was mild compared to that of sodium hypochlorite solution. CONCLUSION: Functional water like SAEW and HAW have a good microbicidal effect under existing organic substance and are also mild to pulp cells.

Seasonal changes in the long-distance linkage disequilibrium in Drosophila melanogaster.

Seasonal environmental changes have the potential to influence the genetic structure of species with a short generation time, such as Drosophila. We previously found the seasonal change in linkage disequilibrium (LD) between the chemoreceptor (Cr) genes in a local Japanese population (Kyoto [KY]). This could be caused by fluctuation in the population size or selection in temporally heterogeneous environments or both. Here, we analyzed the scale of LD between 51 X-linked polymorphisms (10 Cr and 41 non-Cr gene markers) in the 2 seasonal samples from the KY population and an autumn sample from 106 localities in and around Japan (Ja03au). Many of the non-Cr genes have receptor function but fewer functional connections to each other. The magnitude of LD in Ja03au did not significantly differ from that in the KY autumn sample. The lack of local differentiation was confirmed in an autumn sample from another local Japanese population. On the other hand, the magnitude of LD was significantly larger in spring than in autumn in the 2 independent KY samples. This suggests that reduction in the population size during winter increased the magnitude of LD in spring in the mainland population in Japan. Long-distance LD could be a useful measure for assessing seasonal fluctuation in effective population size.

Changes in salivary physiological stress markers associated with winning and losing.

Using a representative table game popular in Japan known as shogi, or Japanese chess, we investigated the effects of winning and losing on saliva composition. The subjects were 90 healthy male university students who were members of a shogi club. Saliva samples were collected immediately before and after playing shogi, and again 30 min later. Salivary cortisol and testosterone levels in the samples were determined by ELISA and EIA, respectively. After finishing each game, the competitiveness of the game was evaluated using questionnaires. In the samples taken after playing shogi, there was an increase in the levels of salivary testosterone and cortisol, regardless of whether the subject won or lost, and the tendency was more pronounced in competitive games. There were no such changes in the control group, who did not play a game prior to providing the samples. Our results suggest that stress response is intimately linked with competition and could be used to determine which players are more capable of handing stress in a competitive environment.