Expression of neprilysin in periodontitis-affected gingival tissues.

OBJECTIVE: Although the pathogeneses of Alzheimer's disease (AD) and periodontal diseases have overlapping features, including ageing and chronic inflammation, the association between AD and periodontitis remains unclear. To explore the pathogenesis of periodontitis, a comprehensive gene expression/transcriptome analysis in periodontitis-affected gingival tissues found that the AD pathway was significantly up-regulated in periodontitis-affected gingival tissues. AD-related genes, amyloid beta precursor protein (APP), interleukin-1 beta and compliment 1QA, were significantly elevated in periodontitis. In the present study, balance between mRNA expression of APP and a potent amyloid degradation enzyme, neprilysin (NEP), as well as protein localisation of APP and NEP were analysed. DESIGN: Eighteen periodontitis-affected and 18 clinically healthy control gingival tissues were taken from patients with severe chronic periodontitis or undergoing tooth extraction. Total RNA was purified and used for quantitative reverse transcription real-time polymerase chain reaction (qRT-PCR). The localisation of APP and NEP was analysed by immunohistochemistry (IHC). RESULTS: Both APP and NEP genes were up-regulated in periodontitis-affected gingival tissues. APP-expressing macrophages and NEP-expressing neutrophils and fibroblasts, reflecting inflammatory stages, were detected in inflamed gingival tissues by IHC. CONCLUSION: The up-regulation of APP and NEP mRNA levels in periodontitis-affected gingival tissues compared with healthy controls was confirmed by qRT-PCR analyses. Since NEP is one of the primary enzymes that degrades amyloid beta, increased NEP mRNA levels in periodontitis may act as an inhibitor of amyloid beta accumulation in gingival tissues, balancing increased APP mRNA expression. However, NEP has several effects including degradation of vasoactive substances; therefore, further sresearch is needed.

Tablets containing a cysteine protease, actinidine, reduce oral malodor: a crossover study.

Tongue coating (TC) mainly consists of protein mostly from exfoliated epithelial cells. Until now, to reduce TC accumulation, only mechanical measures have been available, and the procedure involves unpleasant side effects, such as gagging reflex or carcinogenesis related to mechanical stimulation. We expected that protease might be effective in reducing the accumulation of TC causing oral malodor. The purpose of this study was to determine the effect of long-term use of candy tablets containing protease, actinidine, on both TC accumulation and concentration of volatile sulfur compounds (VSCs) in mouth air. We employed 14 subjects aged 24 to 54 years old for this study, and conducted a double-blind randomized crossover trial. The subjects sucked the tablets containing actinidine three times a day until the sixth day after starting the study. The tablets without actinidine were utilized as a placebo. Measurements of VSC concentration and TC accumulation were carried out before and after chewing tablets on the first day, and also on the seventh day. The levels of VSC and TC significantly (p < 0.05) decreased after tablets were taken on the first day in both the test and placebo groups. There was a statistically significant decrease (p < 0.05) in VSC after seven days of use only in the test group. The results of the study suggest that the tablets containing actinidine had an accumulative effect in reducing VSC in mouth air with long-term use.

Fluoride intake of Japanese infants from infant milk formula.

This study aimed to measure the fluoride (F) content of all infant milk formulas (IMF) available for purchase in Japan and estimate the F exposure of infants whose primary source of nutrition is IMF when reconstituted with different F concentrations of water. Twenty-two commercially available IMFs were purchased from 6 manufacturers in Japan. These IMFs included 21 milk-based products and 1 soy-based product. Each IMF was reconstituted using distilled water and 0.13 µg F/ml fluoridated water according to the manufacturers' instructions. The F concentrations in each sample were measured using the hexamethyldisiloxane diffusion technique and an F ion-selective electrode. The mean F concentration of all products was 0.41 (range 0.15-1.24) µg/g. There were no statistically significant differences among mean F concentrations of newborn milks, follow-on milks and other milks or among manufacturers. The mean F concentration of all products, when reconstituted with distilled water and 0.13 µg F/ml water, was 0.09 and 0.18 µg/ml, respectively. The mean F intake from IMF ranged from 0.039 to 0.134 mg/day with distilled water and from 0.078 to 0.258 mg/day with 0.13 µg/ml fluoridated water, respectively. These results suggested that F intake of infants from IMFs depended on the F concentration of added water, and therefore the risk of dental fluorosis for most Japanese infants would be small since most Japanese municipal water supplies are low in F. However, there was a possibility to exceed the tolerable upper intake level, even under the limit of the law, especially for infants within the first 5 months of life.

Fluoride intake from food and liquid in Japanese children living in two areas with different fluoride concentrations in the water supply.

The purpose of this study was to estimate the average daily amount of fluoride from the diet ingested by Japanese children of ages susceptible to dental fluorosis in two areas with different fluoride concentrations in the water supply. Thirty-eight children aged 2-8 years participated in a survey of fluoride intake. Twenty-one out of 38 children lived in an area in which the community water fluoride concentration was an average of 0.555 ppm (moderate fluoride area: MFA), and 17 lived in a low fluoride area (LFA), which ranged between 0.040 and 0.131 ppm. To measure the fluoride intake, diets were collected with a duplicate-diet technique. The fluoride concentrations in each sample were measured using the diffusion technique of Taves and the electrode technique. Meanwhile, after clinical examinations for dental caries and fluorosis, 228 subjects aged 13-15 years were selected for analysis from the same communities. The mean DMFT in the MFA was significantly lower than that in the LFA. The severest grade of dental fluorosis observed was 'very mild' according to Dean's fluorosis index in both areas. The total daily fluoride intakes were 0.0252-0.0254 mg F/kg/day in the MFA and 0.0126-0.0144 mg F/kg/day in the LFA. Differences in the fluoride concentration of drinking water in this study were reflected in the fluoride intake from the diet in a typical Japanese diet.