Objective:To make an assessment on the genotoxicity caused by black carbon ( BC ) and ozonized black carbon (O3-BC).Methods: In this study, 74 healthy male ICR mice [weighed (28 ± 1.5) g] were randomly divided into 7 groups, including one phosphate buffer solution ( PBS) control group and six particles exposed groups by intratracheal instillation with either BC or O 3-BC at the doses of 50, 100, 200 μg/mouse, respectively.There were 12 mice in the groups of 200μg/mouse and 10 mice in others.The mice were sacrificed 24 h after four intratrachealinstillations .The activities of catalase ( CAT) in serum and the levels of malondialdehyde ( MDA) in lung tissue homogenate were measured . As the DNA damage mark , 8-hydroxyguanosine ( 8-OHdG ) in urine and serum were quantified with ELISA method.Micronucleus test was used for potential genotoxicity of BC and O 3-BC.Hematoxylin and eosin staining was used to stain lung paraffin section .Results:The mice were in good condition during instillation , and the liver coefficient of the test groups was significantly lower than that of the control group (P<0.05).The activities of CAT in serum significantly increased in the 100 μg/mouse and 200μg/mouse groups after being exposed to these two kinds of particles .The micronucleus rate in allthe BC and O3-BC exposed groups increased ( P <0.05), but there was no statistically significant difference among the groups in the levels of 8-OHdG in serum and urine and MDA in lung tissue homogenate .In-flammatory response was found in the lung tissue under the microscope after exposure to BC and O 3-BC. Conclusion:Intratracheal instillation of BC and O 3-BC induced increasing of oxidative stress and genetic damage in mice .But there was no significant difference between these two particles in toxicity .Whether the genotoxicity of O 3-BC is higher than that of BC or not is uncertain .Further research is needed .

Objective:To analyze the epidemiological and clinical characteristics of hand-feet-mouth disease (HFMD).Methods:The clinical and pathogenic data of 1 976 cases with HFMD hospitalized in Public Health Clinical Center of Chengdu from August 2018 to September 2019 were retrospective analyzed.Results:Among the 1 976 cases of HFMD, 1 094 cases (55.36%) were one to two years old, and 803 cases (40.64%) lived in the main urban area. The majority were scattered patients (1 344 cases, 68.02%). There were 1 348(72.7%) of 1 854 cases mainly infected by Coxsackie virus 6 (CV-A6). The main distribution of rashes in children infected by CV-A6 were palm/soles, trunks, limbs, oral ulcer and perioral areal, lips and hip. The types of rash were maculopapule, vesicle, and bulla. Fever (1 543 cases, 78.09%) was the main concomitant symptom. Acute tonsillitis (811 cases, 41.04%), myocardial injury (767 cases, 38.82%), and herpetic angina (658 cases, 33.30%) were the most common complications. The incidence of onychomadesis were nine (7.03%) among the 128 patients during follow-up.Conclusions:CV-A6 is the main pathogen of the HFMD prevalence. Children less than two years old are susceptible and the main symptoms of HFMD are rash and fever.