Objective To investigate the effect of interaction between indoor air pollution and smoking on senile asthma. Methods Households in six low-and middle-income countries： China, Ghana, India, Mexico, Russia, and South Africa, were randomly selected for household surveys, and individual questionnaires were conducted among all members aged 50 years and older. Logistic regression models were used to analyze the relationship between indoor air pollution （cooking fuel, chimney facilities）, smoking （smoking status, smoking frequency, smoking duration）, and senile asthma. Multiplication and addition models were used to assess the effects of interaction between air pollution and smoking on senile asthma. Results A total of 33 327 respondents were included in the analysis, and the overall prevalence of senile asthma in six countries was 3.89% （1 296/33 327）. After adjusting for confounding factors of country, age, gender, marital status, place of residence, education level, physical activity, and family income, the risk of asthma increased among smokers compared with that of non-smokers （OR=1.18, 95% CI： 1.01-1.45）; among the participants with different smoking frequencies, those who smoked occasionally had the highest risk of asthma （OR=1.75, 95% CI： 1.33-2.30）. The interaction analysis showed that besides smoking duration and cooking fuel, there was additive interaction between indoor air pollution and smoking on senile asthma; multiplier interactions between smoking status （interaction OR=1.60, 95% CI： 1.26-2.02）, smoking frequency （interaction OR=1.61, 95% CI： 1.28-2.04）, smoking duration （interaction OR=1.69, 95% CI： 1.39-2.21） and cooking fuel were found to be correlated with the risk of asthma in the elderly. The risk of asthma was highest when two risk factors coexisted. The risk of asthma in smokers using firewood/coal/charcoal as cooking fuel was 1.43 times higher than that of non-smokers using the electricity/gas as cooking fuel （95% CI： 1.17-1.75）. Conclusion Both indoor air pollution and smoking were associated and interacted with senile asthma.

Objective To establish a quantitative detection method of droplet digital polymerase chain reaction （ddPCR） for identification and quantification of enterovirus. Methods The probe concentration and annealing temperature in ddPCR were optimized using enterovirus standards, and the detection range of ddPCR was determined. Viral load assays were performed on 28 clinical samples using optimized reaction conditions. Results In this study, the optimal probe concentration for ddPCR was 0.4 μmol/L, the annealing temperature was 51 °C, the nucleic acid detection range was 3.02-3.59×10⁶ copies/μL, and the detection limit was 3.02 copies/μL. The linear correlation coefficient of the ddPCR method was 0.993 8, showing a good linear relationship. Conclusion This study established a quantification method based on ddPCR for general enterovirus, which can effectively quantify enterovirus load in clinical samples and provide a technique for the determination of viral load in clinical research.

Objective To observe the protective effect of Guangdong herbal tea extract on oxidative damage of rabbit erythrocyte membrane from the perspective of membrane composition, structure and function. Methods The experiment consisted of a control group, H₂O₂ group （1 000 μmol/L）, 0.1 mg group （0.1 mg/ml herbal tea +1 000 μmol/L H₂0₂）, 0.2 mg group （0.2 mg/mL herbal tea +1 000 μmol/L H₂0₂）, and 0.4 mg group （0.4 mg/mL herbal tea +1 000 μmol/L H₂0₂）. Rabbit red blood cell membrane was prepared by Dodge method. The effects of malondialdehyde （MDA）, the carbonyl content of protein, membrane blocking ability, ATPase activity, glutathione peroxidase （GPX）, catalase （CAT） activity, and membrane protein composition on each group were observed. Results Compared with the control group, the carbonyl content of protein and GPX activity were increased, while cell membrane blocking ability, activity of CAT, Ca²⁺Mg²⁺-ATPase, Mg²⁺-ATPase, and Na⁺K⁺-ATPase in H₂O₂ group were decreased （P < 0.01 for all）. Compared with the H₂O₂ group, contents of MDA and DNPH decreased, while the cell membrane blocking rate, and activities of Ca²⁺Mg²⁺-ATPase, Mg²⁺-ATPase, Na⁺K⁺-ATPase, GPX, and CAT increased in the three herbal tea groups （P < 0.05 for all）. Conclusion Guangdong herbal tea extract could inhibit the damage of erythrocyte membrane composition, structure and function caused by hydrogen peroxide.

Objective To construct a small spatial scale dengue risk assessment tool based on the random forest model,so as to provide scientific basis for the prevention and control of dengue fever. Methods Data of dengue case and related factors from February 2012 to September 2014 were used as the training set and random forest regression （RFR） models were constructed separately for frequency, duration and intensity of dengue fever. Data of dengue cases and related factors from October 2014 to March 2015 were used to as the testing set to verify the accuracy of the models. Results The correlation coefficients between incidence and frequency, duration, intensity of dengue fever were all higher than 0.7. Based on the training set, the pseudo R-squareds in the models of frequency, duration, and intensity were 96.72%, 91.98%, and 90.1%; the cross-validated mean square errors （MSEs） of the models were 0.001 9, 1.424 6, and 1.881 1, respectively. By comparing the accuracy of RFR, support vector regression （SVR）, generalized linear model （GLM） and generalized additive model （GAM）, the MSEs of RFR and SVR were much lower than those of GLM and GAM. Conclusion The RFR models constructed using the frequency, duration and intensity of dengue fever as outcome variables and the meteorological, environmental and socioeconomic characteristics as predictors have better accuracy and can be used as a risk assessment tool for preventing and control of the outbreak of dengue fever.

Objective To measure the inter-provincial community health service （CHS） level in China and diagnose the obstacles restricting the CHS level. Methods Average scores of the inter-provincial CHS level across the country was estimated according to the “Evaluation Index System of Community Health Service Quality”. Entropy weight method, exploratory spatial data analysis method and obstacle degree model were used to analyze and evaluate the average scores in 2016. Results The average score of CHS in China was 0.277 3. The highest score of CHS was 0.863 8 in Guangdong, and the lowest was 0.013 6 in Tibet, and the difference between the highest score and the lowest was 0.850 2. The provinces with high levels of inter-provincial CHS were Guangdong, Jiangsu, Shanghai, Zhejiang, and Shandong; the middle and high-level provinces were Hubei, Sichuan, Beijing, Hunan, Henan, Chongqing, and Anhui; the middle and low-level provinces were Fujian and Liaoning, Tianjin, Hebei, and Heilongjiang; the low-level provinces are Yunnan, Inner Mongolia, Guangxi, Xinjiang, Shaanxi, Shanxi, Guizhou, Jiangxi, Gansu, Jilin, Hainan, Ningxia, Qinghai, and Tibet. From the national perspective, the I₆ （bed occupancy rate） and I₇ （mean hospitalization day） were the two major obstacles that hindered the improvement of CHS levels in the central and western provinces. The I₄ （number of admissions） was the primary obstacle to the improvement of CHS in the eastern provinces. Conclusion The levels of CHS in the eastern, central and western regions of China were quite different. The overall CHS level in the eastern provinces was higher than that in the central and western ones. It is suggested that health resources should be allocated reasonably and attention should be paid to the development of low-level areas to narrow the gap of inter-provincial CHS level.