Objective: To investigate the relationship among depression, anxiety, stress and addictive substance use behavior in secondary vocational students. Methods: Cluster sampling method and the Adolescent Health-related Behaviors Questionnaire were used to collect demographic characteristics, psychological symptoms, and addictive substance usage among 5 935 students in nine vocational schools in Chongqing, Zhaoqing, Ningbo, and Taiyuan. Multivariate logistic regression analysis was used to analyze the relationship between the addictive substance use behavior and psychological factors. Results: The detection rates of depression, anxiety and stress were 46.5% (n=2 762), 58.7% (n=3 483), and 29.8% (n= 1 770), respectively. The prevalence of addictive substances was 74.8% (n=4 440), traditional drugs was 0.8% (n=50), new drugs was 2.8% (n=166), other addictive drugs was 4.1% (n=241). Multivariate logistic regression analysis showed that compared with the normal psychological states of secondary vocational students, the OR value of mild depression tendency alcohol and tobacco use behavior of secondary vocational students was 1.45; the OR values of mild anxiety, moderate anxiety, severe anxiety and very serious anxiety were 1.46, 1.46, 1.71, and 1.83, respectively; the traditional drugs use behaviors were 5.51, and 2.61, respectively, for the severe anxiety and very serious anxiety. Compared with the normal psychological state of secondary vocational students, the OR values of the severe anxiety and very severe anxiety were 2.56, and 2.66, respectively, for severe anxiety and very serious anxiety. Compared with normal psychological status of secondary vocational students, the OR values of mild, moderate, severe, and very severe anxiety were 2.14, 2.47, 2.39, and 3.45, respectively; all P values <0.05. Conclusion Anxiety and mild depression were risk factors of tobacco and alcohol use in secondary vocational students; severe and above anxiety were the risk factors of drug use in secondary vocational students; anxiety was the risk factor for other addictive drug use in secondary vocational students.

Objective To identify the causes of nonspecific bands in the detection of a industry standard caf1 gene by polymerase chain reaction(PCR),and to propose a solution to this problem. Methods A total of 112 strains were selected for the experiment, including 40 strains of Yersinia pestis, 72 strains of non-Yersinia pestis;DNA was extracted,and caf1 gene was amplified by PCR;seven non-specific strips were recovered,purified and TA cloning and sequencing; the primer of the caf1 gene was redesigned and validated using all of the strains. Results Using the industry standard caf1 gene primer,DNAs of 40 Yersinia pestis and 72 non-Yersinia pestis were amplified by PCR, 58 non-Yersinia pestis could be amplified with non-specific bands, they were about 400, 500, 600, 700, 800, 900, 1 000 bp. By TA cloning and sequencing, the non-specific bands in the downstream of the industry standard caf1 primer and its reverse complement were amplified. Using the new designed caf1 primer to amplify, 72 non-Yersinia pestis strains showed no non-specific bands. Conclusion Non-specific bands has been amplified in the screening of Yersinia pestis using the primer of the industry standard caf1, and the new caf1 primer can effectively avoid this problem and improve the accuracy of detection.