[PM 2.5 and Emergency Calls for Health with Respiratory Diseases in Chengdu in 2017].

OBJECTIVE: To determine the association between daily particulate matter 2.5 (PM 2.5) mass and emergency calls for help with respiratory diseases. METHODS: Semi-parametric generalized additive model was established to determine the association between daily PM 2.5 and emergency calls for help with respiratory diseases in 2017 in Chengdu, after adjustments for time trend and variations in the days of the week and weather conditions. RESULTS: In 2017, a total of 9 309 emergency calls for help with respiratory diseases were recorded in Chengdu: on average 26 calls a day. Over the year, Chengdu reported a mean PM 2.5 mass concentration of 53.6 µg/m 3, an average temperature of 16.6 ℃, and an average relative humidity of 81.2%. The single pollutant model with lag time effect showed that a 10 µg/m 3 increase in PM 2.5 was associated with an increase of 1.26% (95% confidence interval ( CI) 0.56%-1.97%) emergency calls for help with respiratory diseases. The exposure-response was almost in a direct line. The dual pollutant model found that O 3 8-hour sliding average (O 3-8 h) enhanced the effect of PM 2.5 on emergency calls for help with respiratory diseases. CONCLUSION: Outdoor PM 2.5 is a significant predictor of emergency calls for help with respiratory diseases in Chengdu.

[Study on the association between urinary organic arsenic and 8-hydroxydeoxyguanine in workers exposed to arsenic].

OBJECTIVE: To evaluate the association between metabolism of arsenic and DNA oxidative damage in workers in a arsenic mill. METHODS: Urinary organic arsenic and 8-hydroxydeoxyguanine were detected in 37 workers highly exposed to arsenic and 16 administrative and logistic staff with mild exposure in a arsenic mill in Yunnan province, and also 28 local people who did not have the exposure in the near past time. The correlation between metabolism of arsenic and DNA oxidative damage was evaluated. RESULTS: The urinary organic arsenic concentration was respectively (0.48 +/- 0.37) mg/L and (0.08 +/- 0.05) mg/L for men with high and low exposure, and was respectively 0.11 mg/L and (0.30 +/- 0.24) mg/ L for women with high and low exposure, while it was lower than 0.02 mg/L in the controls. Urinary 8-hydroxydeoxyguanine concentration was (18.07 +/- 11.68) micromol/mol creatinine, (11.79 +/- 8.25) micromol/mol creatinine, (10.07 +/- 3.04) micromol/mol creatinine for the males with high and low exposure and of controls, respectively, (P < 0.05), and it was 84.35 micromol/mol creatinine, (21.27 +/- 5.89) micromol/mol creatinine, (14.43 +/- 2.58) micromol/mol creatinine for females with high and low exposure and of controls, respectively. The female workers exposed to arsenic had higher urinary 8-hydroxydeoxyguanine levels than males did (P < 0.05). The increased tendencies of urinary 8-hydroxydeoxyguanine levels with the organic arsenic concentration were found in workers (r(s) = 0.279, P = 0.019). CONCLUSION: Occupational individuals exposed to arsenic have obvious DNA oxidative damage, which is more severe in females. The difference of metabolism of arsenic may play a key role.

[Experiment research on the location of DNA lesion in the nucleic acid sequence].

OBJECTIVE: To research on establishing a method that can detect the DNA lesion at the level of nucleic acid. METHODS: The TK6 cell was cultured and treated, the genomic DNA was extracted, and the strand cleavage was induced by the endonuclease Hinf I. Then the genomic DNA was amplified by randomized terminal linker-dependent PCR (RDPCR), and hybridized by Southern hybridization with the single-stranded probes of the exon 2 of k-ras gene. The PCR products were sequenced. RESULTS: The clear hybridized band from the products of RDPCR was seen at the expectant position cut by Hinf I. The sequencing analysis showed that the position of DNA lesion linked by the linker was just the restriction site of Hinf I. CONCLUSION: It can be used to detect the DNA lesion at the level of nucleic acid sequence with the combination of sequence and RDPCR technologies.