Personal characteristics related to the risk of adolescent internet addiction: a survey in Shanghai, China.

BACKGROUND: Paralleling the rapid growth in computers and internet connections, adolescent internet addiction (AIA) is becoming an increasingly serious problem, especially in developing countries. This study aims to explore the prevalence of AIA and associated symptoms in a large population-based sample in Shanghai and identify potential predictors related to personal characteristics. METHODS: In 2007, 5,122 adolescents were randomly chosen from 16 high schools of different school types (junior, senior key, senior ordinary and senior vocational) in Shanghai with stratified-random sampling. Each student completed a self-administered and anonymous questionnaire that included DRM 52 Scale of Internet-use. The DRM 52 Scale was adapted for use in Shanghai from Young's Internet Addiction Scale and contained 7 subscales related to psychological symptoms of AIA. Multiple linear regression and logistic regression were both used to analyze the data. RESULTS: Of the 5,122 students, 449 (8.8%) were identified as internet addicts. Although adolescents who had bad (vs. good) academic achievement had lower levels of internet-use (p < 0.0001), they were more likely to develop AIA (odds ratio 4.79, 95% CI: 2.51-9.73, p < 0.0001) and have psychological symptoms in 6 of the 7 subscales (not in Time-consuming subscale). The likelihood of AIA was higher among those adolescents who were male, senior high school students, or had monthly spending >100 RMB (all p-values <0.05). Adolescents tended to develop AIA and show symptoms in all subscales when they spent more hours online weekly (however, more internet addicts overused internet on weekends than on weekdays, p < 0.0001) or when they used the internet mainly for playing games or real-time chatting. CONCLUSIONS: This study provides evidence that adolescent personal factors play key roles in inducing AIA. Adolescents having aforementioned personal characteristics and online behaviors are at high-risk of developing AIA that may compound different psychological symptoms associated with AIA. Spending excessive time online is not in itself a defining symptom of AIA. More attention is needed on adolescent excessive weekend internet-use in prevention of potential internet addicts.

[Cloning of CTB-PROIN fusion gene and its expression in Escherichia coli].

A fusion gene CTB-PROIN, in which Proinsulin gene was fused to the 3' end of CTB gene by a hinge peptide 'GPGP', was constructed and cloned into pET-30a(+) to obtain a prokaryotic expression vector pETCPI. Subsequently the recombinant plasmid pETCPI was transformed into E. coli stain BL21 (DE3). After induced by IPTG, the expression product was analyzed by sodium dodecyl sulphate-polyacrylamide gel (15%) electrophoresis (SDS-PAGE), and its result indicated that the recombinant protein CTB-PROIN was expressed and accumulated as inclusion bodies. The recombinant CTB-PROIN protein accumulated to the level of 25% of total bacterial proteins. After inclusion bodies was denaturalized and refolded in vitro, significant assembly of monomers had occurred, and the recombinant protein represented assembled pentamers. The results of western blotting analysis also demonstrated that the fusion protein could be recognized by the anti-CT and anti-insulin antibody, respectively. In addition, the result of the CTB-PROIN-GM1 binding assay, that the protein could bind to monosialoganglioside specifically, showed it possesed biological activity in vitro. These results provided the possibility of developing a cheaper and more efficient oral vaccine for type I diabetes using such constructs.