Objective : To investigate the status of electronic cigarette use and its influencing factors among residents aged ≥15 years in Chengdu City in 2021 and 2024, so as to provide the evidence for optimizing electronic cigarette control strategies. Methods: Two rounds of cross-sectional surveys were conducted in 2021 and 2024. Multi-stage cluster random sampling method was used to select permanent residents aged ≥15 years in Chengdu City as survey subjects. The Chinese Adult Tobacco Survey Questionnaire was used to collect information on gender, age, and electronic cigarette use. Complex sampling weighting was used to calculate the rate of electronic cigarette use and the proportion of reasons for electronic cigarette use. A complex sampling multivariable logistic regression model was used to analyze the influencing factors for electronic cigarette use. Results: A total of 7 950 and 6 920 people were surveyed in 2021 and 2024, respectively, including 3 868 and 3 653 males (48.65% and 52.79%), and 4 082 and 3 267 females (51.35% and 47.21%), respectively. The rate of electronic cigarette use in 2024 was lower than in 2021 (2.29% vs. 3.15%, P<0.05). In 2024, the rates of electronic cigarette use were lower in males, rural areas, people aged 15-<45 years, educational level of bachelor' s degree or above, occupation in government/public institutions or occupation in enterprises/commercial/service industries, and current smokers compared with 2021, while the rate of electronic cigarette use was higher in residents aged ≥65 years compared with 2021 (all P<0.05). In 2021 and 2024, the main reasons for electronic cigarette use were smoking cessation and the belief that electronic cigarettes are less harmful. Smoking cessation accounted for 27.78% and 23.28%, and the belief that electronic cigarettes are less harmful accounted for 24.26% and 22.10%, respectively. Complex sampling multivariable logistic regression analysis showed that age (15-<25 years, OR=15.682, 95%CI: 5.660-43.450; 25-<45 years, OR=7.463, 95%CI: 2.987-18.647; 45-<65 years, OR=3.425, 95%CI: 1.562-7.510), educational level (bachelor' s degree or above, OR=2.916, 95%CI: 1.444-5.891), and smoking (current, OR=23.992, 95%CI: 8.182-70.353; former, OR=20.393, 95%CI: 6.150-67.624) were influencing factors for electronic cigarette use in 2021. Gender (male, OR=2.279, 95%CI: 1.074-4.832), age (25-<45 years, OR=2.114, 95%CI: 1.148-3.892), educational level (high school/vocational high school/technical secondary school, OR=2.792, 95%CI: 1.414-5.514; bachelor' s degree or above, OR=3.321, 95%CI: 1.567-7.039), occupation (unemployed, retired, and retired, OR=0.449, 95%CI: 0.226-0.892), and smoking (current, OR=10.547, 95%CI: 5.563-19.994; former, OR=8.998, 95%CI: 3.833-21.125) were influencing factors for electronic cigarette use in 2024. Conclusions Compared with 2021, the rate of electronic cigarette use among residents in Chengdu City decreased in 2024. Young people, males, bachelor' s degree or above, and current smokers are the key populations for electronic cigarette control. The cognitive bias held by residents that electronic cigarette can aid in smoking cessation and pose minimal harm needs to be corrected.

Objective To compare the degree of cell injury induced by 3D protein (SDLY11 and SDLY107) of enterovirus 71 (EV71) strains.Methods EV71 strains SDLY11 and SDLY107 were respectively isolated from children with mild and severe hand foot mouth disease.The target genes 11-3D-Flag and 107-3D-Flag were amplified by reverse transcription-polymerase chain reation (RT-PCR) and inserted into the eukaryotic expression vector pcDNA3.1.The recombinant plasmids 11-3D-Flag-pcDNA3.1 and 107-3D-Flag-pcDNA3.1 were transformed into Escherichia.coli DH5α, respectively, and were identified by enzyme digestion and sequencing.The recombinant plasmids were transfected into rhabdomyosarcoma (RD) cells, respectively.Expression of 3D protein was detected by indirect immunofluorescence assay and western blot.Cell injury induced by 3D protein was detected with lactate dehydrogenase (LDH) test, cell proliferation was detected by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenylthiazolium bromide (MTT) test, and cell apoptosis was detected with Annexin-V and PI.Multiple comparisons among groups were analyzed using LSD-t test if multiple sets of variables were consistent with homogeneity of variance.If not, Dunnett T3 test was used.Results The 1 400 bp fragments were amplified by reverse tramscription (RT)-polymerase chain reaction (PCR), and the recombinant plasmids were digested by enzyme and the 1 400 bp and 5 400 bp fragments were obtained and identified.Gene sequencing showed that the sequences were consistent with the target genes.The specific fluorescence was observed by indirect immunofluorescence assay, and the western blot showed that the molecular weight of the target protein was 55×103.The LDH test showed that the A490 of SDLY11 3D protein transfection group (0.790±0.048) was higher than that of SDLY107 3D protein transfection group (0.641±0.018).The difference was statistically significant (t=5.14, P<0.05).The cell membrane damage caused by SDLY11 3D protein was more severe than SDLY107 3D protein.The MTT test showed that the A570 of SDLY11 3D protein transfection group (1.028±0.020) was lower than that of SDLY107 3D protein transfection group (1.081±0.002), and the difference was statistically significant (t=3.31, P<0.05).The effect on cell proliferation activity of SDLY11 3D protein was greater than SDLY107 3D protein.The results of Annexin-V/PI showed that the percentage of apoptotic cells of SDLY11 3D protein transfection group and SDLY107 3D protein transfection group were (1.471±0.246)% and (1.465±0.237)%, respectively, and the difference was not statistically significant (t=0.04, P=0.973).Conclusions Compared with the SDLY11 3D protein, SDLY107 3D protein induces slighter cell injury, has weaker effect on cell proliferation activity, and is more favorable for virus replication in cells.