Association between problematic Internet use, sleep disturbance, and suicidal behavior in Chinese adolescents.

BACKGROUND AND AIMS: This large-scale study aimed to test (a) associations of problematic Internet use (PIU) and sleep disturbance with suicidal ideation and suicide attempts among Chinese adolescents and (b) whether sleep disturbance mediates the association between PIU and suicidal behavior. METHODS: Data were drawn from the 2017 National School-based Chinese Adolescents Health Survey. A total of 20,895 students' questionnaires were qualified for analysis. The Young's Internet Addiction Test was used to assess PIU, and level of sleep disturbance was measured by the Pittsburgh Sleep Quality Index. Multilevel logistic regression models and path models were utilized in analyses. RESULTS: Of the total sample, 2,864 (13.7%) reported having suicidal ideation, and 537 (2.6%) reported having suicide attempts. After adjusting for control variables and sleep disturbance, PIU was associated with an increased risk of suicidal ideation (AOR = 1.04, 95% CI = 1.03-1.04) and suicide attempts (AOR = 1.03, 95% CI = 1.02-1.04). Findings of the path models showed that the standardized indirect effects of PIU on suicidal ideation (standardized ß estimate = 0.092, 95% CI = 0.082-0.102) and on suicide attempts (standardized ß estimate = 0.082, 95% CI = 0.068-0.096) through sleep disturbance were significant. Conversely, sleep disturbance significantly mediated the association of suicidal behavior on PIU. DISCUSSION AND CONCLUSIONS: There may be a complex transactional association between PIU, sleep disturbance, and suicidal behavior. The estimates of the mediator role of sleep disturbance provide evidence for the current understanding of the mechanism of the association between PIU and suicidal behavior. Possible concomitant treatment services for PIU, sleep disturbance, and suicidal behavior were recommended.

The mediating effects of depressive symptoms and sleep quality on the relationship between the non-medical use of prescription drugs and suicidal behaviors among Chinese adolescents.

BACKGROUND: The nature of the relationship between the non-medical use of prescription drugs (NMUPD) and suicide has not been clearly elucidated. Some studies have suggested that the relationship between substance use and suicidal ideation may be spurious and could be explained by other variables. METHODS: A school-based cross-sectional study was performed in Guangzhou. A total of 5853 students completed questionnaires and were included in the study. NMUPD, alcohol use, illicit drug use, depressive symptoms, sleep quality, and suicidal behaviors were assessed. The mediating effects of depressive symptoms and sleep quality on the relationship between NMUPD and suicidal behaviors were examined using a structural equation model. RESULTS: In the simple model without mediation, a positive relationship between NMUPD and suicidal behaviors in adolescents was found, which was independent of effects from the use of other substances. Both depressive symptoms and sleep quality were significant mediators of this relationship. CONCLUSION: Public health and educational professionals should survey depressive symptoms and sleep quality and provide interventions when managing suicidal behaviors among adolescents engaging in NMUPD.

Bullying as a risk for poor sleep quality among high school students in China.

OBJECTIVE: To determine whether involvement in bullying as a bully, victim, or bully-victim was associated with a higher risk of poor sleep quality among high school students in China. METHODS: A cross-sectional study was conducted. A total of 23,877 high school students were surveyed in six cities in Guangdong Province. All students were asked to complete the adolescent health status questionnaire, which included the Chinese version of the Pittsburgh Sleep Quality Index (PSQI) and bullying involvement. Descriptive statistics were used to evaluate sleep quality and the prevalence of school bullying. Multi-level logistic regression analyses were conducted to examine the association between being victimized and bullying others with sleep quality. RESULTS: Among the 23,877 students, 6,127 (25.66%) reported having poor sleep quality, and 10.89% reported being involved in bullying behaviors. Of the respondents, 1,410 (5.91%) were pure victims of bullying, 401 (1.68%) were bullies and 784 (3.28%) were bully-victims. Frequently being involved in bullying behaviors (being bullied or bullying others) was related to increased risks of poor sleep quality compared with adolescents who were not involved in bullying behaviors. After adjusting for age, sex, and other confounding factors, the students who were being bullied (OR=2.05, 95%CI=1.81-2.32), bullied others (OR=2.30, 95%CI=1.85-2.86) or both (OR=2.58, 95%CI=2.20-3.03) were at a higher risk for poor sleep quality. CONCLUSIONS: Poor sleep quality among high school students is highly prevalent, and school bullying is prevalent among adolescents in China. The present results suggested that being involved in school bullying might be a risk factor for poor sleep quality among adolescents.

Nasopharyngeal carcinoma patients with retropharyngeal lymph node metastases: a minimum axial diameter of 6 mm is a more accurate prognostic predictor than 5 mm.

OBJECTIVE: The criteria for the diagnosis of metastatic retropharyngeal lymph nodes (RLNs) have not yet been resolved and are not included in the current edition of the American Joint Committee on Cancer (AJCC) staging system (seventh edition) for the staging of nasopharyngeal carcinoma (NPC). The aim of this study was to use MRI to identify an RLN size criterion that can accurately predict prognosis in patients with NPC. MATERIALS AND METHODS: Eight hundred seventeen patients with newly diagnosed localized NPC were identified. All of the patients underwent MRI before treatment with definitive radiation therapy. All the MRI studies and medical records were reviewed retrospectively. Overall survival (OS), distant metastasis-free survival (DMFS), and local relapse-free survival (LRFS) were assessed using SPSS software (version 17.0). RESULTS: RLN size cutoffs of ≥ 5 mm and of ≥ 6 mm were used. There was no significant difference in OS (p = 0.216), DMFS (p = 0.081), or LRFS (p = 0.067) in patients with RLNs ≥ 5 mm and in those with RLNs < 5 mm. When 6 mm was used as a size cutoff, significant differences in OS (p = 0.000) and DMFS (p = 0.001) were identified; there was no significant difference observed for LRFS (p = 0.380). CONCLUSION: A minimum axial RLN diameter of 6 mm was a more accurate prognostic predictor in NPC patients with RLN metastases than 5 mm.

Manumycin induces apoptosis in prostate cancer cells.

BACKGROUND: Manumycin exhibits an antitumor effect in a variety of cancer cell lines, including prostate cancer cell lines (DU145 and PC-3). Our previous studies demonstrated that manumycin induced the apoptosis of anaplastic thyroid cancer cells and leukemia cells via the intrinsic apoptosis pathway. In the current study, we further evaluated the effect of manumycin in two prostate cancer cell lines (LNCaP and 22Rv1), and here we elucidate some of the underlying mechanisms. MATERIALS AND METHODS: The cell viability of prostate cancer cells was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after treatment with manumycin for 48 hours. Apoptosis was detected by flow cytometry using annexin V and propidium iodide. The expressions of B-cell lymphoma (Bcl)-2 family members and the activations of caspase-9 and caspase-3 were detected by Western blotting. RESULTS: Manumycin treatment resulted in significant decreases in the viabilities of the two prostate cancer cell lines in a dose-dependent manner through apoptosis, and this apoptosis involved caspase-9 activation. A specific inhibitor of caspase-9 protected cells from caspase-3 activation, apoptosis, and cytotoxicity induced by manumycin. We also found that manumycin downregulated Bcl-2 expression and upregulated Bax expression. CONCLUSION: Our data suggest that manumycin induces apoptosis in prostate cancer cells through regulation of the Bcl-2 family involving caspase-9 activation. These results suggest that manumycin may be beneficial for the treatment of prostate cancer.

Nasopharyngeal cancer: impact of skull base invasion on patients prognosis and its potential implications on TNM staging.

PURPOSE: To evaluate patterns of skull base invasion and its possible impact on tumor (T)-staging in nasopharyngeal carcinoma (NPC) using magnetic resonance imaging (MRI). MATERIALS AND METHODS: 838 consecutive newly diagnosed by biopsy proven and untreated patients with NPC underwent MRI. The skull-base invasion of NPC was classified according to their incidence from proximal sites to more distant sites surrounding the nasopharynx as: high (≥35%), medium (≥5-35%), and low (<5%) groups. A retrospective analysis of data consisting of a 5-year follow-up was carried out. The skull base invasion was related to their tumor (T) staging and prognosis at the 5-year follow-up after treatment with definitive radiation therapy. In addition, a survival health-related quality of life (QOL), overall survival (OS), local relapse-free survival (LRFS) and distant metastasis-free survival (DMFS) were also assessed among the three groups. RESULTS: The total incidence of skull-base invasion was 65.51% (549/838). The differences in T-stage distribution, and the total survival health-related QOL, among the three groups were statistically significant (χ(2)=160.45, p<0.005; χ(2)=38.43, p<0.005, respectively). The differences between any two of the three groups were also significant, except when the medium grade was compared to the low grade. Significant differences were observed with regard to 5-year OS (83.2%, 74.7%, 59.2%, p=0.000) and DMFS (95.0%, 88.0%, 88.0%, p=0.016); no significant difference was observed in LRFS (95.3%, 95.6%, 91.23%, p=0.450). CONCLUSIONS: The results indicate that medium and low group displayed similar findings of skull base invasion, and survival status. We, therefore, propose that patients in these two groups be grouped under T4 in the TNM classification that might have a bearing in implementing optimum treatment.

Promoting contraceptive use among female rural-to-urban migrants in Qingdao, China: a comparative impact study of worksite-based interventions.

BACKGROUND: We conducted a comparative study in worksites to assess the impact of sexual health promoting interventions on contraceptive use among female rural-to-urban migrants. STUDY DESIGN: In Qingdao ten manufacturing worksites were randomly allocated to a standard package of interventions (SPI) and an intensive package of interventions (IPI). The interventions ran from July 2008 to January 2009. Cross-sectional surveys at baseline and end line assessed the sexual behaviour of young female migrants. To evaluate the impact of the interventions we assessed pre- and post-time trends. RESULTS: From the SPI group 721 (baseline) and 615 (end line) respondents were considered. Out of the IPI group we included 684 and 603 migrants. Among childless migrants, self-reported contraceptive use increased significantly after SPI and IPI (adjusted odds ratio [aOR] = 3.23; 95% confidence interval [CI] = 1.52-6.84; p < 0.01 and aOR = 5.81; 95% CI = 2.63-12.80; p < 0.001, respectively). Childless migrants older than 22 years reported a greater use after IPI than after SPI. CONCLUSION: Implementing current Chinese sexual health promotion programmes at worksites is likely to have a positive impact on migrant women working in the manufacturing industry of Qingdao. More comprehensive interventions seem to have an added value if they are well targeted to specific groups.

Determinants of unmet need for contraception among Chinese migrants: a worksite-based survey.

BACKGROUND: Considerable sexual and reproductive health (SRH) challenges have been reported among rural-to-urban migrants in China. Predictors thereof are urgently needed to develop targeted interventions. STUDY DESIGN: A cross-sectional study assessed determinants of unmet need for contraception using semi-structured interviews in two cities in China: Guangzhou and Qingdao. RESULTS: Between July and September 2008, 4867 female rural-to-urban migrants aged 18-29 years participated in the study. Of these, 2264 were married or cohabiting. Among sexually-active women (n = 2513), unmet need for contraception was reported by 36.8% and 51.2% of respondents in Qingdao and Guangzhou, respectively; it was associated with being unmarried, having no children, less schooling, poor SRH knowledge, working in non-food industry, and not being covered by health insurance. A substantial proportion of unmarried migrants reported they had sexual intercourse (16.6 % in Qingdao and 21.4% in Guangzhou) contrary to current sexual standards in China. CONCLUSION: The study emphasises the importance of improving the response to the needs of rural-to-urban migrants and recommends strategies to address the unmet need for contraception. These should enhance open communication on sexuality, increase the availability of condoms, and improve health insurance coverage.

[Distributions of primary nasopharyngeal carcinoma tumor and patterns of skull base erosion detected by magnetic resonance imaging].

OBJECTIVE: To evaluate the distributions of primary nasopharyngeal carcinoma (NPC) and the patterns of skull base involvement in NPC patients using magnetic resonance imaging (MRI). METHODS: After the approval of institutional review board and informed consent, 838 consecutive newly-diagnosed and untreated NPC patients were examined by MRI. Their MR images were reviewed by two independent radiologists. RESULTS: Among all cases, the incidence rates of superior side and post-superior side involvement were 98.57% (826/838) and 98.21% (823/838) respectively. The differences were not significant between these two sides (P > 0.05). Lateral side erosion was demonstrated in 784 (93.56%) cases. Posterior side was involved in 391 (46.66%) cases. The total incidence rate of skull base involvement was 65.51% (549/838). According to the anatomic site, the pathways of skull base involvement were classified into 5 spreading routes: anterior; superior; super-lateral; super-anterior and super-posterior. According to the incidence rates and the results of chi-square test, the anatomic sites around the nasopharynx were classified into three groups of risk grades: high-risk (≥ 35%), medium-risk (≥ 5% - 35%) and low-risk (< 5%). CONCLUSION: Skull base involvement of NPC spreads stepwise from proximal site to more distal sites. The area of skull base involvement in NPC is classified into high-grade, medium-grade and lower-grade groups respectively. The high and medium-grade groups are related with T3 stage while the lower-grade group T4 stage. Thus T3 stage should be subdivided into T3a and T3b. These schemes may be useful in a more accurate NPC staging and a delineation of clinical target volume for radiotherapy in NPC patients.

Behavioural development of school-aged children who live around a multi-metal sulphide mine in Guangdong province, China: a cross-sectional study.

BACKGROUND: The deleterious biological effects of low-level, long-term exposure to heavy metals are well known, and children are the most susceptible population. Dabaoshan Mine in the southeast of Guangdong Province is at high risk of discharging multi-metals pollutants into a local river (Hengshihe) and the surrounding area. The present study aimed to estimate relationships between measured multi-metal exposures and the presence of behavioural problems for the school-aged children in the polluted area. METHODS: A cross-sectional study was performed. Children aged 7-16 years living in three villages of the Hengshihe area with different degrees of heavy-metal pollution participated in this study. Local environmental samples (water and crops) and children's hair were collected, and concentrations of heavy metals were determined. The Child Behaviour Check-list (CBCL) was used to assess the presence of behaviour problems. General linear regression was used to analyze the contribution of hair metals to each CBCL subscale with adjustment for socio-demographic confounding factors. RESULTS: Multiple regression analyses revealed significant effects of hair lead, cadmium and zinc levels on CBCL subscales. Log-transformed hair lead, cadmium and zinc levels accounted for an incremental of 8% to 15% variance in anxious/depressed, withdrawn, somatic complaints, social problems, thought problems, attention problems, delinquent behaviour and aggressive behaviour. The concurrent log-transformed hair lead and zinc levels were strongly associated with all subscales while the concurrent log-transformed hair cadmium was only significantly associated with withdrawn, social problems and attention problems. CONCLUSION: This study reveals that heavy metal exposure was associated with increased risk of behavioral problems for school-aged children.

Which preventive measures might protect health care workers from SARS?

BACKGROUND: Despite the use of a series of preventive measures, a high incidence of severe acute respiratory syndrome (SARS) was observed among health care workers (HCWs) during the SARS epidemic. This study aimed to determine which preventive measures may have been effective in protecting HCWs from infection, and which were not effective. METHODS: A retrospective study was performed among 758 'frontline' health care workers who cared for SARS patients at the Second Affiliated Hospital and the Third Affiliated Hospital of Sun Yat-sen University. The HCWs with IgG against SARS and those without IgG against SARS were respectively defined as the "case group" and the "control group", and logistic regression was conducted to explore the risk factors for SARS infection in HCWs. RESULTS: After adjusting for age, gender, marital status, educational level, professional title, and the department in which an individual worked, the results of a multivariate logistic regression analysis indicated that incidence of SARS among HCWs was significantly and positively associated with: performing tracheal intubations for SARS patients, methods used for air ventilation in wards, avoiding face-to-face interaction with SARS patients, the number of pairs of gloves worn by HCWs, and caring for serious SARS cases. CONCLUSION: Some measures, particularly good air ventilation in SARS wards, may be effective in minimizing or preventing SARS transmission among HCWs in hospitals.

Potential infections of H5N1 and H9N2 avian influenza do exist in Guangdong populations of China.

BACKGROUND: Southeast China is one of the sites of influenza origin. During 2003--2004, nine avian influenza outbreaks took place in Guangdong Province. But no human case was reported. To examine the status of potential human infection by human influenza (H1N1, H3N2) and avian influenza (H5N1, H7N7, H9N2) in the avian influenza epidemic area of Guangdong Province, China, we conducted a seroepidemiologic survey in the people of this area from April to June of 2004. METHODS: Three out of 9 H5N1 avian influenza affected poultry areas in Guangdong were randomly selected, and the population living within 3 kilometers of the affected poultries were chosen as the survey subjects. One thousand two hundred and fourteen people were selected from 3 villages at random. Human and avian influenza antibody titers were determined by hemagglutination-inhibition (HI) test and microneutralization test (MNT). RESULTS: The positive rate of antibody to H5N1 was 3.03% in the occupational exposure group and 2.34% in general citizens group; that of H9N2 was 9.52% in the occupational exposure group and 3.76% in the general citizens group. Moreover one case in the occupational exposure group was positive for H7N7. One year later, all previously positive cases had become negative except for one H5N1-positive case. CONCLUSION: The observations imply that H5N1 and H9N2 avian influenza silent infections exist in Guangdong populations.

[Relationship between apoptosis and activity of protein kinase B in adrenocortical cells induced by cadmium chloride].

OBJECTIVE: To study apoptosis induced by cadmium chloride (CdCl2) and the alteration in activity of protein kinase B (PKB/Akt) in adrenocortical cells. METHODS: Fasciculata-glomerulosa (FG) cells of male guinea pigs were dispersed and primarily cultured in vitro. Features of apoptotic cells were observed using combined labeling with annexin-V and propidium iodide (PI) and flow cytometry. The activity of PKB/Akt was determined with immunoprecipitation and the chemiluminescence assay. RESULTS: Apoptosis rate of FG cells increased with dose of CdCl2 two hours after treatment with 6.25-100.00 micromol/L of it, with significant difference in the groups treated with 25.00, 50.00, 100.00, micromol/L of CdCl2, as compared with the control group (P < 0.01). Regression analysis showed that occurrence of apoptosis correlated with the dose of CdCl2 in a dose-response pattern. In the meanwhile, there were obviously elevated percentages of apoptotic cells as the increase in duration of incubation ranging from 5.58% to 73.08% for incubating cells with 50.00 micromol/L of CdCl2, from 15 minutes to 4 hours. Duration of incubating cells with CdCl2 were correlated with occurrence of apoptosis in a time-effect manner. The gray scales of PKB/Akt were manifested to be decreased as the ascending of CdCl2 dosage from 6.25 to 200.00 micromol/L, with the linear correlation. CONCLUSION: 6.25 to 100.00 micromol/L CdCl2 might elicit apoptosis of adrenocortical cells. Meanwhile, PKB/Akt is decreased.

Treatment outcome of new pulmonary tuberculosis in Guangzhou, China 1993-2002: a register-based cohort study.

BACKGROUND: Completion of treatment for tuberculosis (TB) is of utmost priority for TB control programs. The aims of this study were to evaluate the treatment outcome of TB cases registered in Guangzhou during the period 1993-2002, and to identify factors associated with treatment success. METHODS: Two (of eight) districts in Guangzhou were selected randomly as objects of study and their surveillance database was analyzed to assess the treatment outcome and identify factors associated with treatment success for TB cases registered in Guangzhou. Six treatment outcome criteria were assessed based on guidelines set by the World Health Organization (WHO). Logistic regression was used to estimate risk factors for treatment outcome. RESULTS: A total of 6743 pulmonary tuberculosis cases (4903 males, 1840 females) were included in this study. The treatment success rate (including cured and complete treatment) was 88% (95%CI 87%-89%). One hundred and eight-six (2.8%) patients died and 401 (5.9%) patients defaulted treatment. In multivariate analysis, treatment success was found to be associated with young age, lack of cavitation and compliance with treatment. CONCLUSION: The total treatment success rate in the current study was similar to the WHO target for all smear positive cases, while the failure rate and the default rate in 2002 were slightly higher. Good care of elderly patients, early diagnosis of cavitation and compliance with treatment could improve the success rate of TB treatment.

[Process evaluation on a health promotion model regarding smoking prevention among Chinese secondary school students].

OBJECTIVE: To evaluate the process of smoking prevention and control among Chinese adolescent with a model on health promotion in junior high school. METHODS: A cluster-randomized, controlled and schooled-based trial on smoking prevention was conducted among 2343 students at four secondary schools in Huangpu District of Guangzhou. Students 'reports and investigators' daily records were used to evaluate the intervention measures. RESULTS: During the one-year period of intervention (Dec. 2004 through Dec. 2005), eighteen activities had been implemented among students, teachers, parents and cigarette retailers. Ranked by the rate of awareness, the top six activities were shown as follows: "the nicotine toxicity experiment" (90.7%), "agreement of building families free of smoking"(77.7%), "a letter to parents" (77.1%), "no-smoking signs" (76.5%), "Blackboard information about health and smoking" (75.0%), and "signature on the 18th World Day of No Smoking" (70.2%). Among all the activities, "the nicotine toxicity experiment" had the highest rate of participation (88.5%), followed by "a letter to parents" (73.6%), "agreement of building families free of smoking" (69.8%), "health education through experiments"(68.6%), "health education through multimedia" (65.7%) and "signature on the 18th World Day of No Smoking" (65.6%). The top seven activities in which students showed greatest interests were "the nicotine toxicity experiment" (64.5%), "signature on the 18th World Day of No Smoking" (33.0%), "health education through experiments" (31.2%), "health education through multimedia" (29.8%), "class meetings with a thesis of smoking" (26.8%), "health pamphlets" (26.6%), "specific textbooks" (25.9%). The extent of students' general satisfaction to the work of tobacco control in school during the last year was 52.4%. The biggest perceived shortcoming for the intervention plan was the low participation of students. CONCLUSION: Some intervention measures had not been fully carried out among the students and only covered part of them. It is necessary to adjust the previous intervention measures through keeping the nicotine toxicity experiment, health education through multimedia and other measures with extensive participation of students and at the same time, to avoid literal materials, exhibition boards and traditional single-way health education program.

[Study on the impact of related psychological stress and fatigue to different smoking behaviors among undergraduate students].

OBJECTIVE: To explore the relationship between psychological stress, fatigue and different smoking behaviors among undergraduate students. METHODS: 8138 undergraduate students in grade 1 to 3 were sampled with cluster sampling method from a comprehensive university in Guangzhou, and were studied on their psychological stress, peer and self smoking behaviors, as well as socio-demographic factors with a self-administered questionnaire. Physical and mental fatigue was measured by Chalder fatigue scale. A multinomial logistic regression analysis was performed to explore the association between psychological stress, fatigue and different smoking behaviors with 'non-smokers' defined as control group while 'triers' and 'current smokers' as case group, respectively. RESULTS: There were students trying to smoke or becoming current smokers on university campus. After adjusting the effect of relevant socio-demographic factors and peer smoking behavior, physical fatigue (OR = 1.044, 95% CI: 1.013-1.075) and 'worry about current academic and future work' (OR = 1.020, 95% CI: 1.001-1.040) were the risk factors of trying to smoke among male students, while 'study stress (OR = 1.063,95% CI: 1.012-1.117) was the risk factor for female students when start smoking. 'Personnel relationship and environment stress' (OR = 1.152, 95% CI: 1.012-1.312) were the risk factors for female students' current smoking behavior. CONCLUSION: Psychological stress and fatigue were moderately associated with smoking behavior among undergraduate students and the impact was different on different gender and smoking behaviors that suggesting that some specific psychological measures should be taken so as to control different smoking behaviors among undergraduate students.

[Determinants of attempt and success in smoking cessation among male secondary school students].

OBJECTIVE: To investigate the prevalence of smoking cessation in schoolboys and the possibility of success, and examine the predictors of quitting attempt and success. METHODS: In a cross-sectional survey, self-administered questionnaires were answered by 4658 schoolboys to collect the information including their demographic characteristics, school conditions, smoking and health related knowledge and attitudes, and smoking related behaviors. RESULTS: Of the respondents, 7.6% were identified as regular smokers, and 68.6% of the regular smokers declared having tried to quit smoking in past twelve months but only 17.2% of them had succeeded in quitting. The two most popular motivations of quitting were "worrying about cigarettes harm to health" and "others persuading them to quit". Four influencing factors had significant association with the attempt to quit smoking, including ever having been persuaded to quit, health consideration, smoking mostly in bad mood, parents opposition of smoking. Concerning the possibility of success, ever having ever been exposed to anti-smoking propaganda predicted successful cessation while the boys who always smoked outside of schools tended to fail quitting. CONCLUSION: Most of the smoking adolescents have ever tried to quit although the possibility of success is quite low. It' s necessary and important to combine the power of schools, families and communities in helping adolescents quit smoking with suitable methods considering their physical and psychological characteristics.

[Analysis on factors influencing the smoking behaviors among male secondary school students under the structural equation model].

OBJECTIVE: To analyze the direct and indirect outcomes of influencing factors on smoking behaviors among adolescents. METHODS: Self-administered questionnaires were used to collect smoking-related information from 2021 respondents. Measurement models were built by confirmatory factor analysis and parameters were estimated by ERLS method. The final structural equation model was determined by comprehensive evaluation and necessary modification. RESULTS: Three latent variables were extracted from 10 manifest variables of environment, while only one latent variable was identified from 9 manifest variables of attitudes. The goodness of fit for the structural equation model was satisfactory that all indices had met corresponding requirements. The final model could explain 38.8% of the variance of smoking behaviors. Four factors (smoking environment, smoking restriction from parents and teachers, determination of cigarette refusal and attitudes toward smoking) were directly affecting the smoking behaviors, while another three factors (grade, health knowledge and school environment) had indirect impacts. According to the percentages of their contribution, the risk factors were ranked as follows: smoking environment (45.76%), attitudes toward smoking (19.88%) and grade at school (0.44%). Similarly, the top protective factor were: determination of cigarette refusal (16.61%), followed by smoking restriction from parents and teachers (10.51%), health knowledge (3.89%) and school environment (2.92%). CONCLUSIONS: Heath knowledge had minor effect on smoking in adolescents but could indirectly affect their smoking behaviors through changing their belief. Grade at school had a doubled influence on smoking, but mainly served as a risk factor. Tobacco control measures for adolescents should not only be limited to health education but environment factors as well.

Anti-SARS-CoV immunoglobulin G in healthcare workers, Guangzhou, China.

To determine the prevalence of inapparent infection with severe acute respiratory syndrome (SARS) among healthcare workers, we performed a serosurvey to test for immunoglobulin (Ig) G antibodies to the SARS coronavirus (SARS-CoV) among 1,147 healthcare workers in 3 hospitals that admitted SARS patients in mid-May 2003. Among them were 90 healthcare workers with SARS. As a reference group, 709 healthcare workers who worked in 2 hospitals that never admitted any SARS patients were similarly tested. The seroprevalence rate was 88.9% (80/90) for healthcare workers with SARS and 1.4% (15/1,057) for healthcare workers who were apparently healthy. The seroprevalence in the reference group was 0.4% (3/709). These findings suggest that inapparent infection is uncommon. Low level of immunity among unaffected healthcare workers reinforces the need for adequate personal protection and other infection control measures in hospitals to prevent future epidemics.