2,3,7,8-Tetrachlorodibenzo-p-dioxin promotes migration ability of primary cultured rat astrocytes via aryl hydrocarbon receptor

Emerging evidence showed that 2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD) could induce expression of certain reactivation-associated genes in astrocytes, however, the consequent cellular effects and molecular mechanisms are still unclear. During the process of astrocyte reactivation, migration is a critical cellular event. In the present study, we employed woundhealing assay and Transwell? motility assay to explore the effects of TCDD on cell migration in primary cultured rat cortical astrocytes. We found that upon TCDD treatments at relative low concentrations(10^(-10) and/or 10^(-9) mol/L), the ability of primary astrocytes to migrate horizontally and vertically was promoted. In line with this cellular effect, the mR NA expression of two promigratory genes, including cell division cycle 42(CDC42) and matrix metalloproteinase 2(MMP2)was induced by TCDD treatment. Dioxin exerts its toxic effects mainly through aryl hydrocarbon receptor(AhR) pathway. So the role of AhR pathway in the pro-migratory effects of TCDD was examined using an AhR antagonist, CH223191. We found that application of CH223191 significantly reversed the pro-migratory effects of TCDD. Interestingly, the basal ability of horizontal migration as well as basal levels of CDC42 and MMP2 expression were dramatically reduced suggesting a possible physiological role of AhR in maintaining the endogenous migration ability of the primary astrocytes. These findings support the notion that dioxin promotes astrocyte reactivation at molecular and cellular levels.

Exposure measurement, risk assessment and source identification for exposure of traffic assistants to particle-bound PAHs in Tianjin, China

To investigate the levels of exposure to particulate-bound polycyclic aromatic hydrocarbon （PAH） and to estimate the risk these levels pose to traffic assistants （TAs） in Tianjin （a rnegacity in North China）, a measurement campaign （33 all-day exposure samples, 25 occupational-exposure samples and 10 indoor samples） was conducted to characterize the TAs＇ exposure to PAHs, assess the cancer risk and identify the potential sources of exposure. The average total exposure concentration of 14 PAHs was approximately 2871 ＋ 928 ng/rn3 （on-duty）, and 1622 ＋ 457 ng/m3 （all-day）. The indoor PAHs level was 1257 ＋ 107 ng/m3. After 8000 Monte Carlo simulations, the cancer risk resulting from exposure to PAHs was found to be approximately 1.05 x 10-4. A multivariate analysis was applied to identify the potential sources, and the results showed that, in addition to vehicle exhaust, coal combustion and cooking fumes were also another two important contributors to personal PAH exposure. The diagnostic ratios of PAH compounds agree with the source apportionment results derived from principal component analysis.

Changes in muscle strength and risk of cardiovascular disease among middle-aged and older adults in China:Evidence from a prospective cohort study

Background:Evidence indicates that low muscle strength is associated with an increased cardiovascular diseases(CVDs)risk.However,the association between muscle strength changes based on repeated measurements and CVD incidence remains unclear.Methods:The study used data from the China Health and Retirement Longitudinal Study in 2011(Wave 1),2013(Wave 2),2015(Wave 3),and 2018(Wave 4).Low muscle strength was defined as handgrip strength<28 kg for men or<18 kg for women,or chair-rising time≥12 s.Based on changes in muscle strength from Waves 1 to 2,participants were categorized into four groups of Normal-Normal,Low-Normal,Normal-Low,and Low-Low.CVD events,including heart disease and stroke,were recorded using a self-reported questionnaire during Waves 3 and 4 visits.Cox proportional hazards models were used to investigate the association between muscle strength changes and CVD incidence after multivariable adjustments.Hazard ratios(HRs)and 95%confidence intervals(95%CIs)were estimated with the Normal-Normal group as the reference.Results:A total of 1164 CVD cases were identified among 6608 participants.Compared to participants with sustained normal muscle strength,the CVD risks increased progressively across groups of the Low-Normal(HR=1.20,95%CI:1.01-1.43),the Normal-Low(HR=1.35,95%CI:1.14-1.60),and the Low-Low(HR=1.76,95%CI:1.49-2.07).Similar patterns were observed for the significant associations between muscle strength status and the incidence risks of heart disease and stroke.Subgroup analyses showed that the significant associations between CVD and muscle strength changes were consistent across age,sex,and body mass index(BMI)categories.Conclusions:The study found that muscle strength changes were associated with CVD risk.This suggests that continuous tracking of muscle status may be helpful in screening cardiovascular risk.