[Effects of periodontitis on bone and tryptophan metabolism of gut microbiota in estrogen-deficient mice].

Objective: To study the effects of periodontitis on bone and tryptophan metabolism of gut microbiota in the context of estrogen deficiency. Methods: Thirty-two female C57BL6/J mice were randomly divided into four groups based on table of random numbers (n=8 in each group): Sham group, in which mice were given sham surgery; Sham_Lig group, in which mice were given sham surgery and were induced to periodontitis by ligating the bilateral maxillary second molars with 5-0 silk threads at the fourth week; Ovx group, in which mice were given bilateral ovariectomy; Ovx_Lig group, in which mice were given bilateral ovariectomy and were induced to periodontitis at the fourth week. After 8 weeks of ligation, the mice of 4 groups were euthanized for collecting the samples of femur, tibia, mandible and skull. Those samples were scanned by micro-CT to measure the bone mineral density (BMD), bone volume versus total volume ratio (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th) and trabecular spacing (Tb.Sp). The cecum contents of 4 groups of mice were collected for gut microbiota 16S rRNA gene sequencing. The tryptophan and its metabolites in intestinal tracts were detected by liquid chromatography-mass spectrometry. Pearson correlation analysis was performed to analyze the correlation between the abundance of gut microbiota and the content of tryptophan and its metabolites. Results: Femur BMD [(82.23±3.97) mg/cm3], BV/TV [(9.25±1.37)%] and Tb.Th [(70.95±5.70) µm] in Ovx_Lig group were significantly lower than Ovx group [(96.30±3.76) mg/cm3 (P=0.004); (14.45±1.55)% (P=0.022) and (87.58±8.02) µm (P<0.001), respectively]. The ß-diversity analysis of gut microbiota based on Bray-Curtis distance showed that samples of Ovx_Lig group and Ovx group were obviously grouped. Linear discriminant analysis effect size (LEfSe) showed that Alistipes was the representative genus in Ovx_Lig group. The relative abundance of Alistipes in Ovx_Lig group [(0.42±0.14)%] were significantly higher than that in Ovx group [(0.17±0.05)%] (t=4.45, P<0.001). Tryptophan metabolism analysis showed that the content of kynurenic acid [(531.12±158.60) ng/g] in Ovx_Lig group were significantly higher than that in Ovx group [(400.42±57.96) ng/g] (t=2.19, P=0.046). And the content of indole-3-carbaldehyde [(383.37±144.06) ng/g] in Ovx_Lig group were significantly lower than Ovx group [(701.72±141.93) ng/g] (t=4.45, P<0.001). Correlation analysis showed that relative abundance of Alistipes was positively correlated with kynurenic acid (r=0.32, P=0.088), while negatively correlated with indole-3-carbaldehyde (r=-0.32, P=0.088). Conclusions: Periodontitis can induce bone destruction of femur in estrogen-deficient mice, the mechanism of which may be related to Alistipes in gut and the tryptophan metabolites kynurenic acid and indole-3-carbaldehyde.

Effect of cigarette tax increase on cigarette consumption in Taiwan.

OBJECTIVES: This study evaluates the effect of a 5 New Taiwan Dollar (NTD 5) Health and Welfare Tax increase on the consumption of domestic and imported cigarettes and cigars. METHODS: Using statistics published annually from 1971 through 2000, we set up a model based on the Central Bureau of Statistics (CBS) demand model to estimate price and expenditure elasticity coefficients of cigarettes and cigars. RESULTS: Our results showed that the price elasticity coefficients for domestic and imported cigarettes were -0.644 and -0.822. The consumption of imported cigarettes was reduced by 7.51 packs per capita, and the consumption of domestic cigarettes was reduced by 15.21 packs per capita. Total per capita consumption of cigarettes was reduced by 22.72 packs (18%). CONCLUSIONS: From the public health and financial perspectives, the increase in this excise tax on tobacco to the Taiwan government will have significant effect in reducing cigarette consumption; it will also generate additional tax revenues.