[Surveillance data on notifiable infectious diseases among students aged 6-22 years in China, 2011-2016]

Objective: To analyze the epidemiological characteristics of notifiable infectious diseases among Chinese students from 2011 to 2016 and to provide reference for the effective prevention and control programs on infectious disease among students. Methods: Both morbidity and mortality of notifiable infectious diseases among Chinese students aged 6-22 years from 2011 to 2016 were analyzed, with main characteristics of the disease described. Results: During 2011 to 2016, morbidities of Categories A, B and C infectious diseases among the Chinese students aged 6-22 years showed a decreasing trend, from 248.24/100 000 in 2012 to 158.57/100 000 in 2016. Mortality rates of Category A, B and C infectious diseases had also decreased from 0.12/100 000 in 2011 to 0.07/100 000 in 2016. The average morbidity of the top four diseases from Category A and B infectious diseases appeared as: tuberculosis (16.24/100 000), scarlet fever (9.39/100 000), hepatitis B (7.69/100 000) and bacillary and amebic dysentery (7.15/100 000). The average rates of mortality on the top four diseases appeared as: rabies (0.044 8/100 000), HIV/AIDS (0.027 7/100 000), tuberculosis (0.008 0/100 000) and Japanese encephalitis (0.005 9/100 000). The average rates of morbidity on the top four diseases appeared as: mumps (75.81/100 000), hand-foot-mouth disease (28.55/100 000), other infectious diarrhea (22.41/100 000) and influenza (15.67/100 000) in the Category C. Reported death cases were from hand-foot-mouth disease (11 cases), influenza (9 cases), mumps (1 case) and rubella (1 case). The prevalence rates varied among different student populations, with higher HIV/AIDS, hepatitis B and tuberculosis rates among college and senior high school students, while higher mumps, influenza and hand-foot-mouth disease rates among primary school and junior high school students. Conclusions: Both morbidity and mortality of notifiable infectious diseases among Chinese students aged 6-22 years had decreased significantly in 2011-2016. However, the major infectious diseases had become new challenges among students. HIV/AIDS had become a key infectious disease among college students and the relatively high prevalence of tuberculosis was seen in college and high school students.

[The change in mortality and major causes of death among Chinese adolescents from 1990 to 2016]

Objective: To analyze the change in mortality and major causes of death among Chinese adolescents aged 10-19 years from 1990 to 2016. Methods: Data of death for Chinese adolescents aged 10-19 years were extracted from the Global Burden of Disease Study 2016 (GBD 2016). The data was used to describe the change in mortality of Chinese adolescents from 1990 to 2016.Top 15 causes of death were compared between 1990 and 2016. Results: From 1990 to 2016, the all-cause mortality of Chinese adolescents aged 10-19 years old dropped from 102.5/100 000 to 41.2/100 000, reaching about a half of the global average (78.6/100 000) but still almost twice as high as the average of high-income countries (24.3/100 000) by 2016; the reduction in mortality was higher among females than that among males (decreased 68.7% vs. 54.7%), and among adolescents aged 10-14 years than that among those aged 15-19 years (decreased 62.1% vs. 57.1%). During the 26-year period, the cause-specific mortality of all top 15 causes saw sharp decreases. Among them, communicable, maternal, and nutritional diseases saw the most significant decrease (78.1%), and its proportion in all adolescent deaths fell from 11.1% to 6.1%. Meanwhile, non-communicable diseases and injuries saw relatively small decreases (58.2% and 57.3% respectively), and their proportions rose from 33.4% and 55.6% to 34.8% and 59.1%, respectively. The top 5 causes of death changed from drowning (17.39/100 000 in mortality, 17.0% in proportion), road injuries (14.77/100 000, 14.4%), self-harm (11.44/100 000, 11.2%), leukemia (5.48/100 000, 5.4%) and interpersonal violence (3.12/100 000, 3.0%) in1990 into road injuries (9.27/100 000, 22.5%), drowning (6.83/100 000, 16.6%), leukemia(2.73/100 000, 6.6%), self-harm (2.53/100 000, 6.2%) and congenital birth defects (1.76/100 000, 4.3%) in 2016, and tuberculosis, poisonings and rheumatic heart disease had dropped out of the top 15 in 2016. Conclusion: The mortality of Chinese adolescents aged 10-19 years has decreased significantly, but still higher than developed countries. Since 1990, injuries,especially for road injuries and drowning, have always been the leading causes of death among Chinese adolescents aged 10-19 years, followed by non-communicable diseases.

[Clinical features and gene analysis of TBC1D24 gene mutation related early-onset focal myoclonic epilepsy]

Objective: To investigate the clinical features and genetic characteristics of patients with TBC1D24 gene mutation related early-onset focal myoclonic epilepsy. Methods: Clinical data of 3 patients with TBC1D24 gene mutation related early-onset focal myoclonic epilepsy of Xuanwu Hospital from November 2016 to June 2017 was collected and analyzed.Candidate gene mutations were screened by second generation sequencing. Results: Among the 3 patients, 1 was male and 2 were females.Seizure onset age was 4 months, 3 years and 5 years after birth respectively. Two patients had family history of epilepsy.They all had prolonged episodes of focal myoclonus. Two patients had mental retardation.Scalp electroencephalograms (EEG) was recorded in all 3 cases and myoclonic seizures were captured.The ictal EEGs were normal in all cases. In one patient, the ictal EEG of generalized seizure showed alpha rhythm originating from left fronto-central region. Brain magnetic resonance imaging (MRI) was normal in 2 patients. Abnormal signal was found bilaterally in cerebellum in 1 patient. The gene screening showed that two patients carried compound heterozygous mutation of TBC1D24 gene and one carried homozygous mutation, all of which were de novo mutations.All the patients were treated with multiple antiepileptic drugs (AEDs) and seizures were uncontrolled in 2 patients. One patient was followed up for 10 months without recurrence. Conclusions: TBC1D24 gene related early-onset focal myoclonic epilepsy is clinically characterized by early onset, prolonged focal myoclonus which relieved with sleep, mental retardation and poor response to AEDs.The interictal and ictal EEG usually show normal. Genetic analysis can assist in diagnosis and genetic counseling.

[The association between the malnutrition and blood pressure in Chinese Han students aged 7-18 years in 2014]

Objective: This study aimed to explore the association between malnutrition and the level of blood pressure (BP) as well as elevated BP (EBP) in Han students aged 7 to 18 years in China. Methods: 170 037 subjects with normal nutritional status and malnutrition were enrolled in this study from 2014 Chinese National Surveys on Students' Constitution and Health with a multi-stage stratified cluster random sampling framework covering 31 provinces, autonomous regions and municipalities after the exclusion of 44 317 overweight and obese students. According to the standard of "Screening Standard for Malnutrition of School-age Children and Adolescents" (WS/T456-2014), the nutritional status of children were classified into two categories, normal nutritional status and malnutrition containing stunting, mild wasting and moderate severe wasting. The level of BP and prevalence of EBP were compared between students with normal nutritional status and malnutrition. The multivariate logistic regression model was used to analyze the association between malnutrition and EBP. Results: The levels of systolic BP (SBP) and diastolic BP (DBP) in Chinese Han students aged 7-18 years who were non-overweight and non-obesity status were (103.4±12.3) and (64.7±9.5) mmHg (1 mmHg=0.133 kPa), respectively. The prevalence of EBP, systolic EBP and diastolic EBP in Chinese Han malnourished students (N=21 012) were 3.1% (n=649), 1.5% (n=324) and 2.1% (n=445), respectively, which was significantly lower than those (N=148 320) with normal nutritional status (4.5% (n=6 707), 2.6% (n=3 872) and 2.7% (n=3 959)), and the corresponding differences were statistically significant (P<0.05). The OR (95%CI) between malnutrition and EBP was 0.68 (0.62-0.73), which were 0.65 (0.58-0.72) and 0.68 (0.60-0.77) for boys and girls. The OR (95%CI) between EBP and stunting as well as mild wasting and moderate severe wasting were 0.69 (0.62-0.77), 0.63 (0.55-0.72) and 0.79 (0.60-1.05), respectively. Conclusion: The level of BP and prevalence of EBP in Chinese Han students with malnutrition were lower than those with normal nutritional status. The negative correlation existed between malnutrition and EBP in Chinese Han students aged 7 to 18 years.

[The epidemiological characteristics and related factors of dyslipidemia among children and adolescents aged 6-17 years from 7 provinces in China, 2012]

Objective: To investigate the prevalence and related factors of dyslipidemia among children and adolescents aged 6-17 years in 7 provinces in China. Methods: Using the method of stratified cluster random sampling, 93 primary and secondary schools were selected from Guangdong, Hunan, Liaoning provinces, Shanghai, Chongqing, Tianjin municipalities and Ningxia Hui Autonomous Region in China, 2012. A total of 16 434 students aged 6-17 years old with completed physical and lipid profiles parameters were selected into this study from above 93 primary and secondary schools. Dyslipidemia was determined by the definition of Expert Advice on Prevention and Treatment of Dyslipidemia in Children and Adolescents in 2009. Logistic regression model was used to explore the factors related to dyslipidemia. Results: The prevalence of elevated total cholesterol, elevated triglyceride, elevated low-density lipoprotein cholesterol, low high-density lipoprotein cholesterol, and dyslipidemia was 5.4% (887 cases), 15.7% (2 578 cases), 3.0% (492 cases), 13.5% (2 221 cases) and 28.5% (4 679 cases) among children and adolescents aged 6-17 years, respectively. Sugary drinks intake ≥once per week (OR=1.14; 95%CI: 1.05-1.24), sedentary time >10 hours per day (OR=1.14, 95%CI: 1.01-1.28), overweight (OR=1.50, 95%CI: 1.33-1.70), and obesity (OR=2.62, 95%CI: 2.31-2.96) were significantly associated with the prevalence of dyslipidemia. Conclusion: The prevalence of dyslipidemia was high among children and adolescents aged 6-17 in 7 provinces in China, 2012. Sugary drinks intake ≥once per week, sedentary time >10 hours per day, overweight and obesity might be the risk factors of dyslipidemia among children and adolescents.

[Analysis on prevalence of physical fitness and related influencing factors among Chinese Han students aged 13-18 years in 2014]

Objective: To analyze the prevalence of physical fitness among Chinese Han students aged 13-18 years in 2014, and explore related influencing factors. Methods: This study recruited 106 881 Han students aged 13-18 years who had taken physical fitness test from Chinese National Survey on Students' Constitution and Health in 2014. After the exclusion of 1 047 students without complete records of physical fitness test, 105 834 students were included in the final analysis. According to the National Student Physical Health Standard modified in 2014, seven indicators including body mass index, vital capacity, 50-m run, sit-and-reach, standing broad jump, pull-ups/curl-ups and endurance run were tested to calculate the total score of students' physical fitness. Students with score ≥60 were regarded as qualified students. Multivariate non-conditional logistic regression model was used to analyze influencing factors of physical fitness. Results: Among Chinese Han students aged 13-18 years, the total score was 70.1±10.7 and the qualified rate was 83.9% (n=88 813). Boys (83.5% (44 197/52 910)) had a lower qualified rate of physical fitness than girls (84.3% (44 616/52 924)) (P<0.001), and 13-15 age group (86.5% (46 255/53 465)) was higher than the 16-18 age group (81.3% (42 558/52 369)) (P<0.001). Except for 16-18-year-old boys from central region, normal body mass index, eastern region, good socioeconomic status, enough PE class, exercise time ≥1 h/d, homework time ≥2 h/d, TV time <1 h/d were all related to high qualified rates of physical fitness (P<0.05). Conclusion: Chinese Han students aged 13-18 years were in good physical condition. The qualified rates of physical fitness were significantly different by gender and age groups. Nutritional status, region, socioeconomic status, PE class, exercise time per day, homework time per day, and TV time per day were related factors of physical fitness.

[Association between speed and endurance performance with sleep duration in children and adolescents]

OBJECTIVE

To analyze the association between sleep duration and athletic performance, and provide scientific basis to improve the 50 m and endurance performance in children and adolescents.

METHODS

All the 119 462 subjects aged 9-15 years in both genders were sampled from 2014 National Physical Fitness and Health Surveillance by using stratified random cluster sampling method, to measure the height, weight, 50 meters and endurance performance and investigate sleep duration with questionnaire. Their body mass indexes (BMI) were calculated and the students' 50 m, endurance run scores and sleep durations were assessed. Binary Logistic regression was used to analyze the difference between the different sleep groups, and multifactor Logistic regression was used to analyze the relationship between the sleep condition and athletic performance.

RESULTS

The prevalence of insufficient sleep was 94.67% in the total subjects, the prevalence was higher among the girls (95.26%)than the boys (94.09%, χ²=80.99, P<0.001), and higher among the urban (95.41%) than the rural students(93.93%, χ²=128.48, P<0.001).The children with sufficient sleep had better performance in 50 m and endurance run scores( χ²_{50 m}=10.10, P_{50 m}＜0.01; χ²_{endurance run}=21.76, P<0.001). Logistic regression analysis after controlling the gender, area, grade and BMI showed that children with adequate sleep showed better results(OR_{50 m}=1.14, 95%CI_{50 m}=1.05-1.23, P_{50 m}<0.01; OR_{endurance run}=1.21, 95%CI_{endurance run}=1.11-1.31, P_{endurance run}<0.001). As for gender, the excellent rates of 50 m and endurance run scores in the boys with adequate sleep were higher (P<0.001), but there were no significant difference in 50 m and endurance run excellent rates in the girls of different sleep conditions. The excellent rates of 50 m and endurance run in the urban children and the endurance rate in the rural children and adolescents with adequate sleep were higher than those with insufficient sleep (P<0.01) while there were no significant difference in the 50 m excellent rates between the different sleep groups in rural areas. The 50 m and endurance run excellent rates of the children and adolescents with adequate sleep in each grade were higher than those of the children in the same grade with insufficient sleep (P_{primary students' endurance performance}<0.001, and the rest P<0.05). Children and adolescents with normal BMI and overweight who slept well had better performance in 50 m (P<0.05). The endurance run excellent rate of children and adolescents with adequate sleep in each BMI group was higher than that in children and adolescents with insufficient sleep in the same BMI group (P_malnutrition<0.01, P_normal<0.01, P_overweight<0.05, P_obesity<0.05). The children and adolescents were divided into different groups according to the sleep duration,the one who slept less than 7 hours had lower 50 m excellent rate than the other groups with longer sleeping duration (P<0.01) and the rate in the ones who slept more than 9 hours was the highest (P<0.001).The endurance excellent rate in the children and adolescents who slept more than 9 hours was significantly higher than that in the other groups (P<0.001).There was no significant dose-response relationship in excellent rates and sleep durations.

CONCLUSION

The prevalence of insufficient sleep has increased, and the sleep condition in children and adolescents is severe. Children and adolescents with sufficient sleep have better athletic performance, so we should strengthen the prevention and control of the lack of sleep in children and adolescents.

[Association between the blood pressure status and nutritional status among Chinese students aged 7-18 years in 2014: based on the national blood pressure reference for Chinese children and adolescents]

OBJECTIVE

To analyze the epidemic situation of blood pressure (BP) status and its association with nutritional status among Chinese children and adolescents aged 7-18 years old in 2014, and to provide important scientific basis for the control of students' hypertension.

METHODS

All the subjects aged 7 to 18 years in both genders were sampled from 2014 Chinese national surveys on students' constitution and health. BP status was evaluated according to Chinese national gender-, age- and height-specific references, including hypertension (HTN), elevated hypertension (elevated HTN), isolated systolic HTN (SHTN), isolated diastolic HTN (DHTN) and mix HTN. Their nutritional status was evaluated using the international obesity task force (IOTF) definition, including thinness (severe thinness and moderate thinness), normal, overweight and obesity (severe obesity and moderate obesity). The Logistics method was used to analyze the association between BP status and nutritional status. The population attributable risk (PAR%) of overweight and obesity for BP status was calculated.

RESULTS

The prevalence of HTN and elevated HTN among the Chinese children and adolescents aged 7-18 years in 2014 was 14.9% and 9.2%, respectively. And the prevalence of isolated SHTN, isolated DHTN and mix HTN was 3.1%, 8.8% and 3.0%, respectively. The prevalence estimates for HTN differed the greatest for the boys, those in rural, those with high age, those in the East, and those with high BMI. The highest prevalence of HTN was detected in those with severe obesity with 44.2% and 38.8% in the boys and girls respectively, which was 2.8-fold and 3.7-fold than those with normal groups. The negative association was detected between HTN and thinness, but the positive association with overweight and obesity. The PAR% of HTN due to overweight and obesity was 16.2%, and the expected prevalence of HTN was 12.5% if controlling for overweight and obesity. Higher PAR% of isolated SHTN and mix HTN due to overweight and obesity was detected in the Chinese children and adolescents with proportions of 28.7% and 35.1%.

CONCLUSION

The prevalence of HTN among the Chinese children and adolescents aged 7-18 years was still high, whose components mainly focused on isolated DHTN. Overweight and obesity can increase the risk of HTN in children and adolescents significantly, especially for isolated SHTN and mix HTN. Controlling for overweight and obesity can decrease the risk of HTN among Chinese national children and adolescents largely, which can play an important role in preventing the occurrence of chronic disease in adults.

[Association between cesarean birth and the risk of obesity in 6-17 year-olds]

Objective: To explore the association between cesarean section and obesity in child and adolescent. Methods: In this study, a total number of 42 758 primary and middle school students aged between 6 and 17 were selected, using the stratified cluster sampling method in 93 primary and middle schools in Hunan, Ningxia, Tianjin, Chongqing, Liaoning, Shanghai and Guangdong provinces and autonomous regions. Log-Binomial regression model was used to analyze the association between cesarean section and obesity in childhood or adolescent. Results: Mean age of the subjects was (10.5±3.2) years. The overall rate of cesarean section among subjects attending primary or secondary schools was 42.3%, with 55.9% in boys and, 40.6% in girls respectively and with difference statistically significant (P<0.001). The rate on obesity among those that received cesarean section (17.6%) was significantly higher than those who experienced vaginal delivery (10.2%) (P<0.001). Results from the log-binomial regression model showed that cesarean section significantly increased the risk of obesity in child and adolescent (OR=1.72, 95%CI: 1.63-1.82; P<0.001). After adjusting for factors as sex, residential areas (urban or rural), feeding patterns, frequencies of milk-feeding, eating high-energy foods, eating fried foods and the levels of parental education, family income, parental obesity, physical activity levels, gestational age and birth weight etc., the differences were still statistically significant (OR=1.48, 95%CI: 1.39-1.57; P<0.001). Conclusion: The rate of cesarean section among pregnant women in China appeared high which may significantly increase the risk of obesity in child or adolescent.

[Trends in overweight and obesity among Chinese children of 7-18 years old during 1985-2014]

Objective: To investigate the trends in overweight and obesity in Chinese students during 1985-2014. Methods: Data were collected from the Chinese National Survey on Students Constitution and Health in 1985, 1995, 2000, 2005, 2010, and 2014, with the sample size of 409 946, 204 977, 216 786, 234 421, 215 319, and 214 354, respectively. The prevalence of overweight and obesity as well as the increase rates were calculated based on the body mass index (BMI) percentile criteria of Working Group on Obesity in China (WGOC). Results: The prevalence of overweight and obesity in 2014 was 19.4% (41 608/214 354) among 7-18 y Chinese children. The prevalence of overweight and obesity was 24.2% (25 975/107 216) among boys, and 14.6% (15 633/107 138) among girls, with the prevalence among boys exceeding girls (P<0.001). The prevalence of overweight and obesity was 22.3% (23 911/107 239) among urban students, and 16.5% (17 697/107 115) among rural students, with the prevalence among urban students exceeding rural students (P<0.001). The prevalence in 2014 differed among provinces, ranging from 2.3% (Hainan Province 166/7 200) to 16.3% (Tianjin 168/7 186). During 1985-2014, the prevalence of overweight and obesity among 7-18 y Chinese children increased continuously, with the annual increase rate of overweight ranging 0.27%-0.63%, and the annual increase rate of obesity ranging 0.10%-0.58%. The annual increase rates in 2010-2014 of obesity among the urban boys, urban girls, rural boys and rural girls were 0.62%, 0.42%, 0.79%, and 0.49%,respectively, peaking the annual increase rates during 1985-2014. Conclusion: The prevalence of overweight and obesity among 7-18 y Chinese children increased continuously during 1985-2014, with the annual increase rate of obesity in 2010-2014 peaking the increase rates during 1985-2014. There were gender and regional differences in the prevalence of overweight and obesity among 7-18 y Chinese children in 2014.

[The epidemic status and secular trends of myopia prevalence for Chinese children and adolescents aged 7-18 years from 2005 to 2014]

Objective: To investigate the characteristics of geographic distribution and change trend of myopia prevalence for children and adolescents aged 7-18 years old from 2005 to 2014, which provides the basis for the prevention of myopia. Methods: Research material was selected from the data of 2005, 2010, and 2014 Chinese National Survey on Students Constitution and Health, including 31 provinces (with the exception of Hong Kong, Macao, and Taiwan). The complete detection data of binoculus in children and adolescents aged 7-18 years old were selected as our research objects. The research objects of three studies were 233 505, 216 474, and 215 160, respectively. We analyzed the characteristics of geographic distribution and change trend of myopia prevalence for children and adolescents aged 7-18 years old in 31 provinces from 2005 to 2014. Results: The overall myopia detection rates in Chinese children and adolescents aged 7 to 18 years old in 31 provinces were 47.4% (111 707/235 505), 55.6% (120 456/216 474), and 57.2% (122 965/215 160) in 2005, 2010 and 2014, respectively. The growth range in this two phases were 8.0 percentage points, and 1.6 percentage points, respectively, and the difference was statistically significant (P<0.05). The detection rate of Myopia was growing quickly from 2005 to 2010 and only three provinces were in the situation of decline state including Tianjin, Hainan, and Ningxia. 90.3 percent (28/31) of provinces were in the situation of growth state and the growth range was 1.3%-22.3%. The growth of myopia was in the situation of slowdown from 2010 to 2014, and 38.7 percent (12/31) of the provinces were in negative growth districts including Hebei, Shanxi, Inner Mongolia, Zhejiang, Fujian, Shandong, Hubei, Guangxi, Guizhou, Tibet, Qianghai, and Xinjiang. The growth range in other provinces was 0.4%-24.7%. Conclusion: The myopia detection rate was at a higher level and growing constantly in China. There was large difference for myopia of children and adolescents among the 31 provinces. However, the overall growth rate of myopia in children and adolescents was in the situation of a relatively low level form 2010 to 2014.

[Study on the disease burden of Chinese adolescent in 2015]

Objective: To discuss the main causes and risk factors of disability and death among current Chinese adolescents. Methods: Subnational data of China from Global Burden of Disease Study 2015 (GBD 2015) was used to rank the causes and risk factors leading to death and disability adjusted life years (DALY) in Chinese adolescents aged between 10 and 19 years old, and thereby to analyze the main cauese and risk factors of death and DALY among Chinese adolescents in different genders. Results: In 2015, among Chinese adolescents aged 10-19 years old, the total DALY was 13 million 490 thousand years, and the total number of deaths was 63 258 cases. The top 3 causes of DALY were skin and subcutaneous diseases, iron-deficiency anemia and road injuries, resulting in DALY (constituent ratio) of 1 411 (10.5%), 1 094 (8.1%) and 1 029 (7.6%) thousand years respectively. The top 3 causes of death were road injuries, drowning and leukemia, causing 13 881 (21.9%), 9 895 (15.6%) and 4 620 (7.3%) deaths (constituent ratio) respectively. The top 3 risk factors of DALY were iron deficiency, alcohol use and drug use, causing 1 094 (8.1%), 487 (3.6%) and 220 thousand years (1.6%) DALY (constituent ratio) respectively. The top 3 risk factors of death were alcohol use, occupational injuries and drug use, causing 5 957 (9.4%), 1 523 (2.4%) and 810 (1.3%) deaths respectively. Conclusion: Unintentional injury was the top cause of DALY and death in Chinese adolescents, followed by skin and subcutaneous diseases and iron-deficiency anemia. Iron deficiency and alcohol use were the top two risk factors of DALY and death.

[Analysis on prevalence of physical activity time <1 hour and related factors in students aged 9-22 years in China, 2014]

Objective: To explore the prevalence of physical activity time <1 hour and related factors in students aged 9-22 years in China. Methods: A total of 220 159 students (110 039 boys and 110 120 girls) aged 9-22 years who completed the questionnaire of physical activity and lifestyle behaviors were selected from " 2014 National Physical Fitness and Health Surveillance" for the current study. All the participants were divided into 2 groups, i.e. physical activity time <1 hour and physical activity time ≥1 hour according the suggestion of Central Government, stratified by age and gender. χ(2) tests were used to compare the difference in the prevalence of physical activity time <1 hour between boys and girls in every age groups. Univariate and multivariate log-binomial regression models were used to explore the factors that influenced the prevalence of physical activity time <1 hour. Results: The boy's prevalence of physical activity time <1 hour was 73.3%, with the lowest (57.0%) in 9-years-old group, and highest (82.5%) in 18 years old group. The girl's prevalence of physical activity time <1 hour was 79.1%, with the lowest (60.1%) in 9-years-old group, and highest (89.8%) in 21 years old group. Overall, The prevalence of physical activity time <1 hour was significantly higher in girls than in boys (P<0.001), and the prevalence were significantly higher in girls than in boys in all the age groups (P<0.001), and it was observed that the prevalence of physical activity <1 hour increased with age in both boys and girls (P<0.001). Multivariate log-binomial regression model found that being girl (PR=1.05, 95%CI: 1.05-1.06), parents' disliking children to participate physical activity (PR=1.08, 95% CI: 1.07-1.09), heavy homework (PR=1.13, 95% CI: 1.12-1.14), long homework time (PR =1.08, 95%CI: 1.07-1.08), long time spending on electronic screen watching (PR=1.01, 95%CI: 1.00-1.01) and disliking physical class (PR=1.11, 95%CI: 1.10-1.12) could be the risk factors for physical activity time <1 hour, however, living in rural area (PR=0.99, 95% CI: 0.98-0.99) and no supporting from parents for children to participate physical activity (PR=0.99, 95%CI: 1.98-1.00) could be the protective factors, but no consistent association with the time of TV watching was observed (P=0.226). Conclusions: The prevalence of physical activity time <1 hour was high in students aged 9-22 years in China. Female, parents; disliking children to participate physical activity, heavy homework, long homework time, long electronic screen watching time and disliking physical class might be the risk factors.

[Prevalence of myopia and increase trend in children and adolescents aged 7-18 years in Han ethnic group in China, 2005-2014]

Objective: To understand and evaluate the prevalence of myopia and its trend in children and adolescents aged 7-18 years in Han ethnic group in China from 2005 to 2014, and provide evidence for the prevention of myopia. Methods: The data of 2005, 2010 and 2014 Chinese National Students Constitution and Health Surveys were collected. The children and adolescents with complete detection data of binoculus were selected as study subjects. The sample size of three studies were 233 108, 215 319 and 212 743, respectively. The method of curve fitting was used to simulate the myopia detection increase model and analyze the gender and area specific myopia detection increase trends and characteristics from 2005 to 2014. Results: The overall myopia detection rate increased gradually in the children and adolescents aged 7 to 18, which was 47.5% in 2005, 55.5% in 2010 and 57.1% in 2014, respectively. The increase slowed in 2014. A"parabola" shape of myopia detection increase rate was observed. Myopia detection rate increased with age before puberty and decreased with age after puberty gradually. A"cross phenomenon" of myopia detection increase was observed in boys and girls between urban and rural areas. The increase of myopia detection was mainly in urban students before puberty and in rural students after puberty. The age of myopia prevalence peak has become earlier constantly in children and adolescents aged 7-18 years from 2005 to 2014, which was 13 years old in 2005, 12 years old in 2010 and 11 years old in 2014. The increase rate was about 7%. During 2005-2014, the increase rate of myopia detection gradually increased in younger students and tended to zero in older students. Conclusion: The detection rate of myopia was still high in children and adolescents in China. The age of myopia prevalence peak has become earlier gradually.

[Analysis of association between appendicular skeletal muscle mass index and main anthropometric parameters among overweight and obese adults in China]

Objective: To investigate the associations between the appendicular skeletal muscle mass index and main anthropometric parameters, and to provide clues for preventing the reduction of skeletal muscle mass among overweight and obese adults in China. Methods: 1 488 volunteered participants who resided in Beijing longer than one year, between 22 and 55 years old, with self-report BMI ≥24 kg/m(2) were recruited from April to May 2014. 171 participants whose BMI ≤24 kg/m(2) or with organic diseases at the first physical examination were excluded, finally 1 317 overweight/obese participants (male and female were 507, and 810, respectively) were enrolled into the present study. After measuring the anthropometric parameters and body composition by the DXA, Pearson correlation analysis and multiple linear regression models were used to analyze the associations between the appendicular skeletal muscle mass index and main anthropometric parameters. Results: The average age of males and females was (35.6±8.4) and (38.2±9.4) years old, respectively. The females' mean levels of body fat percentage, BMI, waist circumference, hip circumference, and bone mineral density were (41.59±4.14)%, (29.00±3.75) kg/m(2), (92.56±9.00) cm, (101.74±6.75) cm, and (1.20±0.10) g/cm(2), respectively; and the males' mean levels were (34.22±4.61)%, (30.07±4.12) kg/m(2), (99.63±9.49) cm, (102.93±7.28) cm, and (1.28±0.11) g/cm(2), respectively. The mean level of appendicular skeletal muscle mass and skeletal muscle mass index in males were (26.98±3.88), and (8.96±1.02) kg, respectively, which were significantly higher than it in females ((18.57±2.61), and (7.26±0.83) kg, respectively) (P<0.001). For male, the correlation coefficients of skeletal muscle mass index with BMI, waist circumference, hip circumference, body fat percentage and bone mineral density were 0.814, 0.601, 0.637, 0.558, and 0.434, respectively; for female, the correlation coefficients of skeletal muscle mass index with BMI, waist circumference, hip circumference, body fat rate and bone mineral density were 0.761, 0.534, 0.585, 0.610, and 0.304, respectively. The correlations were statistically significant (P<0.001). Multiple linear regression analysis showed that the skeletal muscle mass index of male decreased with the increase of age (β=-0.01, 95%CI:-0.01-0.00) and body fat percentage (β=-0.13, 95%CI:-0.15--0.12) (P<0.05), while increased with the increase of BMI (β=0.31, 95%CI: 0.29-0.32) and bone mineral density (β=0.54, 95%CI: 0.10-1.01) (P<0.05). The skeletal muscle mass index of female decreased with the increase of age (β=-0.01, 95%CI:-0.01-0.00) and body fat percentage (β=-0.12, 95%CI:-0.14--0.12) (P<0.05), while increased with the increase of BMI (β=0.26, 95%CI: 0.25-0.28) and hip circumference (β=0.01, 95%CI: 0.00-0.02) (P<0.05). Conclusion: The skeletal muscle mass index of male was higher than it of female. For male, the skeletal muscle mass index might be associated with age, BMI, body fat percentage and bone mineral density. While for female, the skeletal muscle mass index might be associated with age, BMI, body fat percentage and hip circumference.

[A cross-section study on physical endurance level in primary and middle school students in China, 2014]

Objective: To understand the physical endurance level of primary and middle school students in China in 2014, and identify the factors influencing students'physical endurance. Methods: Data were collected from"National School Student Physical Fitness and Health Surveillance in 2014" , a total of 142 708 primary and middle school students with complete information were included in the analysis. The age, gender and area specific failure rates of endurance running of students were analyzed, the differences were analyzed with χ(2) test, and the factors influencing students' physical endurance were identified with log-binomial regression model. Results: Among the 142 708 students, the failure rate of endurance running was 21.6% (30 867/142 708). The failure rate was 23.7% (16 891/71 388) in boys and 19.6% (13 976/71 320) in girls (χ(2)=347.73, P<0.05). And it was 24.8% in students in urban area (17 713/71 378), higher than that in students in rural area (18.4%, 13 154/71 330) (χ(2)=855.29, P<0.05). The failure rate of endurance running showed an upward trend with age. Insufficient physical education class hour (OR=1.13, 95%CI: 1.11-1.15), not taking breakfast daily (OR=1.22, 95%CI: 1.20-1.25), daily physical exercise time<1 hour (OR=1.44, 95%CI: 1.40-1.48), the screen watching time>2 hours (OR=1.16, 95%CI: 1.14-1.19) and overweight or obesity (OR=1.90, 95%CI: 1.86-1.95) might be the risk factors for the failure of physical endurance. Conclusion: The physical endurance of primary and secondary students in China was not optimistic, and the factors influencing their physical endurance included gender, living area, physical education class time, daily homework time, breakfast, daily exercise time and nutrition status.

[The endemic distribution and related factors of elevated blood pressure among Chinese children and adolescents aged 7-18 years in 2014]

Objective: To investigate the endemic distribution and related factors of elevated blood pressure in Chinese children and adolescents aged 7 to 18 years old. Methods: A total of 214 354 students aged 7 to 18 years old with data integrity of height, weight, and blood pressure were selected from Chinese National Survey on Students Constitution and Health in 2014, including 31 provinces (with the exception of Hong Kong, Macao, and Taiwan) in China. The criterion of elevated blood pressure was defined by the diagnosis and treatment guideline of high blood pressure in US children and adolescent. The differences of elevated blood pressure between boys and girls and different groups of nutritional status were calculated by Chi-square test. Results: The mean values of systolic pressure and diastolic pressure were (104.8 ± 12.8) mmHg (1 mmHg=0.133 kPa), and (65.4 ± 9.7) mmHg, respectively. The rate of elevated blood pressure in Chinese children and adolescents aged 7 to 18 years old was 6.4% (13 558/214 354), as well as 7.0% (7 537/106 982) in boys, and 5.7% (6 131/106 979) in girls (P<0.001). Meanwhile, the rate of elevated blood pressure was 3.2% (321/10 127), 4.9% (7 887/161 419), 9.8% (2 472/25 292), and 17.5% (2 988/17 051) in wasting group, normal group, overweight group and obesity group, respectively, which indicated a rising trend from wasting to obesity among four nutritional status groups(P<0.001). Conclusion: The rate of elevated blood pressure in Chinese boys was higher than girls, especially in overweight and obese students. Therefore, the effective intervention on child and adolescent with overweight or obesity will become the key work on the prevention of high blood pressure in the future.

[Analysis of the epidemiological characteristics of metabolic syndrome among 10-16 adolescents in 7 provinces in China, 2012]

Objective: To investigate the prevalence of metabolic syndrome (MS) among children and adolescents aged 10-16 years old in 7 provinces in China. Methods: Using the method of stratified cluster random sampling, 93 primary and secondary schools were selected from Guangdong, Hunan, Liaoning, Shanghai, Chongqing, Tianjin, and Ningxia provinces in China. A total of 9 296 students aged 10-16 years old with complete physical and biochemical parameters were selected as the subjects of the present study from above 93 primary and secondary schools. MS was determined using the definition of 'guideline of 2010 Chinese children and adolescents MS definition and treatment'. The standardized age-sex composition of the 2010 census was used to standardize the MS detection rate of every province. Chi-square test was used to compare the difference of MS prevalence among participants with different characteristics. Results: The prevalence of MS was 4.1% (384/9 296) among children and adolescents aged 10-16 years old in 7 provinces in China. The prevalence of MS among males was 5.0% (237/4 754), which was significantly higher than females (3.2%) (147/4 542) (P<0.05). Stratified by nutrition conditions, the prevalence of MS was 0, 0.6% (39/6 733), 8.9% (104/1 170), 30.0% (241/803) for thin, normal weight, overweight, and obese population, respectively. The MS prevalence increased with the increase of body mass index (BMI) (P<0.001). Stratified by provinces, the prevalence of MS was the highest in Tianjin (9.2%) and the lowest in Hunan province (0.8%). Conclusion: The prevalence of MS was high among children and adolescents aged 10-16 years old in 7 provinces in China. MS prevalence among males was higher than females; MS prevalence among overweight/obese population was higher than normal weight population. The detection rate of metabolic syndrome was different in different provinces.

Development of polymorphic SSR markers in the razor clam (Sinonovacula constricta) and cross-species amplification

Next-generation sequencing provides large-scale sequencing data with relative ease and at a reasonable cost, making it possible to identify a large amount of SSR markers in a timely and cost-effective manner. On the basis of the transcriptome database of Sinonovacula constricta obtained by Illumina/Solexa pyrosequencing, 60 polymorphic SSR markers were developed and characterized in 30 individuals. The number of alleles per polymorphic locus ranged from 2 to 7 with an average of 3.75 alleles. The observed and expected heterozygosities varied from 0.050 to 1.000 and from 0.050 to 0.836, respectively. Nineteen loci significantly deviated from Hardy-Weinberg equilibrium (P < 0.01) after Bonferroni's correction for multiple tests. In addition, interspecific transferability revealed that 20 polymorphic loci in Solen linearis were first characterized in this study. To the best of our knowledge, this is the highest number of SSRs in S. constricta and the first report of cross-species amplification. These novel polymorphic SSR markers will be particularly useful for conservation genetics, evolutionary studies, genetic trait mapping, and marker assisted selection in the species.

Development of novel polymorphic microsatellite markers for the blood clam Tegillarca granosa by pyrosequencing

Large amounts of expressed sequence tags (ESTs) generated using next-generation sequencing technologies provide a cost-effective and valuable genomic resource for the development of microsatellite markers. In this study, we isolated 115 novel polymorphic microsatellite markers for the blood clam Tegillarca granosa from ESTs in 454 sequencing data. All the loci were characterized in 30 individual clams from a natural population in Xiangshan (Zhejiang Province, China). The number of alleles per locus varied from 2 to 10, with an average of 3.78. The observed and expected heterozygosities ranged from 0 to 1 and from 0.040 to 0.799, respectively. The polymorphic information content (PIC) ranged from 0.038 to 0.825, and 29 highly polymorphic loci (PIC ≥ 0.5) and 42 moderately polymorphic loci (0.25 < PIC < 0.5) were identified. Thirty-eight of the 115 loci deviated significantly from the Hardy-Weinberg equilibrium (P < 0.01) after a Bonferroni correction. A BlastX search revealed that 46 (40%) of the polymorphic loci identified were from transcript regions of known genes. The microsatellite markers developed in the present study will greatly enrich the microsatellite resources of T. granosa, and are available for further population genetic analysis, genetic trait mapping, and molecular-assisted selection.

Microsatellite marker analysis reveals the distinction between the north and south groups of hard clam (Meretrix meretrix) in China

Meretrix meretrix is one of the important commercial bivalves in China. A total of 198 individual clams were collected from 5 locations characteristic of the clam's 5 main natural habitats in China, that is, Shandong, Jiangsu, Fujian, Guangdong, and Guangxi. Ten polymorphic microsatellite markers were selected to examine the genetic diversity and identify genetic differences between the 5 populations. A total of 183 alleles across 10 loci were detected in the individual clams. The observed heterozygosity and expected heterozygosity ranged from 0.197 to 0.7026 and from 0.6264 to 0.9408, respectively. The genetic diversity within samples was high (8.6-11.2 alleles per locus, observed heterozygosity = 0.25-0.875 and expected heterozygosity = 0.6848-0.9259). Most of the genotype distributions significantly deviated from Hardy-Weinberg equilibrium. Genetic structure analysis showed that the 5 populations could be divided into 2 groups, the north and south groups. Neighbor-joining analysis revealed a clear distinction between the north group (Shandong and Jiangsu) and the south group (Fujian, Guangdong, and Guangxi). Locus MM1031 was used to distinguish between groups. Our results can be used for population identification and crossbreeding of M. meretrix.

Bioaccumulation of heavy metals in fish and Ardeid at Pearl River Estuary, China

Sediment, fish (tilapia, Oreochromis mossambicus and snakehead, Channa asiatica), eggs and eggshells of Little Egrets (Egretta garzetta) and Chinese Pond Herons (Ardeola bacchus) were collected from Mai Po Ramsar site of Hong Kong, as well as from wetlands in the Gu Cheng County, Shang Hu County and Dafeng Milu National Nature Reserve of Jiangsu Province, China between 2004 and 2007 (n=3-9). Concentrations of six heavy metals were analyzed, based on inductively coupled plasma optical emission spectrometry (ICP-OES). Significant bioaccumulations of Cd (BAF: 165-1271 percent) were observed in the muscle and viscera of large tilapia and snakehead, suggesting potential health risks to the two bird species, as the fishes are the main preys of waterbirds. Significant (p<0.01) linear relationships were obtained between concentrations of Cd, Cr, Cu, Mn, Pb and Zn in the eggs and eggshells of various Ardeid species, and these regression models were used to extrapolate the heavy metal concentrations in the Ardeid eggs of Mai Po. Extrapolated concentrations are consistent with data in the available literature, and advocate the potential use of these models as a non-invasive sampling method for predicting heavy metal contamination in Ardeid eggs.

Autoimmune thyroid disease: mechanism, genetics and current knowledge

Recent epidemiological studies recognized a steady increase in the incidence of different autoimmune endocrine disorders, including autoimmune thyroid disease (AITD). The etiology of AITD is multifactorial and involves genetic and environmental factors and apparently with a strong preponderance in females. There are mainly two types of AITD, Graves' disease and Hashimoto's disease and both of these show strong association in age groups above 45-50 years. Among environmental factors smoking and alcohol have significant effects, both protective as well as for aggravating the disease, even though the precise nature of these effects are not clearly known. There are elevated levels of circulating antibodies against the thyroid proteins, mainly thyroid oxidase, thyroglobulin and thyroid stimulating hormone receptor, in patients with Graves' disease or Hashimoto's disease. Linkage and association studies in AITD identified several major genes that are relevant for the onset of AITD, including the thyroid-specific genes, thyroglobulin and thyroid-stimulating hormone receptor and also many immune-regulatory genes. In this review we addressed many aspects of AITD including disease mechanisms, involved thyroid antigens, environmental factors and genetic factors.

Biota-sediment accumulation factor (BSAF), bioaccumulation factor (BAF), and contaminant levels in prey fish to indicate the extent of PAHs and OCPs contamination in eggs of waterbirds

Samples of pond sediment, fish, and shrimp were collected from the Ramsar site at Mai Po marshes, Hong Kong (south China), and samples of pond sediment, fish, and shrimp, as well as eggs of water birds (Chinese Pond Herons (Ardeola bacchus) and Little Egrets (Egretta garzetta)), were collected from two smaller wetland sites at Jiangsu Province (mid-China), between 2004 and 2007. Accumulation levels of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the biota were used to calculate biota-sediment accumulation factor (BSAF) and bioaccumulation factor (BAF). For fish and shrimp, BSAFs of OCPs (3.8-56) were greater than those of PAHs (0.12-6.3). BSAFs and BAFs of 11-79 and 4-34, respectively, were registered for OCPs in eggs of the birds and were greater than those for PAHs (0.11-1.5 and 0.02-1.3, respectively). Assuming that fish were the main prey of the birds, greater bioaccumulation of OCPs was detected for both bird species (BAFs =4.5-34), while accumulation of PAHs was only detected in Little Egret (BAF=1.3). A significant linear relationship (p<0.01) was observed between concentrations of OCPs in bird eggs and in the prey fish. The present study provides a new possibility of using OCP levels detected in prey fish to predict the extent of OCPs contamination in eggs of waterbirds including the endangered species, as a noninvasive method.

A novel quantitative trait locus for Fusarium head blight resistance in chromosome 7A of wheat

A Chinese Spring-Sumai 3 chromosome 7A disomic substitution line (CS-Sumai 3-7ADSL) was reported to have a high level of Fusarium head blight (FHB) resistance for symptom spread within a spike (Type II) and low deoxynivalenol accumulation in infected kernels (Type III), but a quantitative trait locus (QTL) on chromosome 7A has never been identified from this source. To characterize QTL on chromosome 7A, we developed 191 7A chromosome recombinant inbred lines (7ACRIL) from a cross between Chinese Spring and CS-Sumai 3-7ADSL and evaluated both types of resistance in three greenhouse experiments. Two major QTL with Sumai 3 origin, conditioning both Type II and III resistance, were mapped in the short arm of chromosomes 3B (3BS) and near the centromere of chromosome 7A (7AC). The 3BS QTL corresponds to previously reported Fhb1 from Sumai 3, whereas 7AC QTL, designated as Fhb7AC, is a novel QTL identified from CS-Sumai 3-7ADSL in this study. Fhb7AC explains 22% phenotypic variation for Type II and 24% for Type III resistance. Marker Xwmc17 is the closest marker to Fhb7AC for both types of resistance. Fhb1 and Fhb7AC were additive, and together explained 56% variation for Type II and 41% for Type III resistance and resulted in 66% reduction in FHB severity and 84% reduction in deoxynivalenol (DON) content. Haplotype analysis of Sumai 3 parents revealed that Fhb7AC originated from Funo, an Italian cultivar. Fhb7AC has the potential to be used in improving wheat cultivars for both types of resistance.