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Objective To investigate the characteristics on the time of sunshine exposure in Chinese primary and middle school students.Methods A total of 43 771 primary and middle school students were randomly selected from 12 provinces in China.A self-reported questionnaire was used to understand their time of sunshine exposure on weekdays and weekends as well as related family information and behaviors.x2 test was used to compare the hours of sunshine exposure among different groups.Multivariate logistic regression analysis was conducted to identify the influencing factors.Results Results from the current survey indicated that the average time of sunshine exposure on weekdays and weekends were 2.49 and 3.22 hours,respectively.On weekdays,proportions of students with time of sunshine exposure ≤2 h/d or ＞2 h/d were 60.81％ and 39.19％,respectively.On weekends,the proportions became 44.05％ and 55.95％,respectively.On weekdays,the time of sunshine exposure as ≤2 h/d was significantly different among factors as sex,urban or rural area,residential area,self-rating academic performance,type of housing or ways of commuting to school.On weekends,the time of sunshine exposure ≤2 h/d were significantly different among sex,residential areas,self-rating academic performance,type of housing and ways of commuting to school.Data from the multivariate logistic regression analysis showed that the limited sunshine exposure was significantly associated with factors as:type of primary schools,being girls,students living in the urban area or living in central or western areas,with normal or better academic performances,living in a fiat apartment and the time spent on watching video program ＞2 h/d both on weekdays and weekends.Conclusion The time of sunshine exposure seemed not enough among school students and significant differences were seen among different groups.
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<p><b>OBJECTIVES</b>To explore the association between elevated light levels in classrooms and change in vision acuity among elementary and secondary students.</p><p><b>METHODS</b>A total of 4 elementary (grade 1-5) and secondary (grade 7-8) schools in urban and rural areas in Sujiatun, Shenyang, China were selected by cluster sampling as experimental schools, and lighting systems have been rebuilt to improve the ambient light levels in 56 classrooms in November 2012. The control schools were chosen for the comparable academic burden and adjacent location to experimental schools, 4 schools in all. Cluster sampling of all students in the selected schools as the subjects was carried out. A total of 2 092 students were chosen as experimental group and 1 595 students were in the control group. The luxmeter was used to measure illuminance of classrooms in two groups at baseline, and intervention for 1 month, respectively.Students in both groups were underwent 3 times for vision acuity examination by standard logarithmic visual acuity chart at baseline, intervention for 6 month and intervention for 1 year, respectively. The light levels of desk and blackboard in two groups were compared by Wilcoxon test. Multivariate analysis of covariance with repeated measures was performed to assess three vision acuity results between groups.</p><p><b>RESULTS</b>After intervention, the average illuminance of desk (117.5 vs 532.5 lx, Z = -5.38, P < 0.001) and blackboard (75.6 vs 423.5 lx, Z = -5.38, P < 0.001) and uniformity of desk (Z = -4.28, P < 0.001) with new lighting were improved significantly than that with old lighting, however the uniformity of blackboard was lower than baseline significantly (0.64 vs 0.70, Z = -2.34, P = 0.019). The average scores of vision acuity in students at baseline, intervention for 6 month and intervention for 1 year were 4.87 ± 0.23, 4.84 ± 0.25 and 4.85 ± 0.23 in experimental group, and 4.88 ± 0.22, 4.84 ± 0.25 and 4.81 ± 0.27 in control group, respectively. The significant differences between groups were found and F values were 1.41, 0.13, 19.99, P values were 0.235,0.724, <0.001. At last the average vision acuity in experimental group were significantly better than that in control group either among elementary (4.90 ± 0.20) vs (4.87 ± 0.21) score, F = 13.61, P < 0.001 or secondary students (4.73 ± 0.28) vs (4.68 ± 0.32) score, F = 14.25, P < 0.001.</p><p><b>CONCLUSIONS</b>Visual acuity loss could be decreased in students with elevated light levels which may slow the response to myopiagenic stimuli for eyes, therefore the ambient light levels of blackboard and desk in classroom should be improved.</p>
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Adolescent , Child , Humans , China , Lighting , Schools , Students , Visual AcuityABSTRACT
Objective To explore the effects of trimetazidine on myocardial free radical inj ury induced by pirarubicin,and to clarify the protective effect and mechanism of trimetazidine on myocardial inj ury induced by pirarubicin.Methods 3 6 Wistar rats were randomly divided into pirarubicin group (n= 1 3 ), trimetazidine intervention group(n=13)and control group (n=10).The rats in pirarubicin group and trimetazidine intervention group were inj ected with pirarubicin 2.5 mg · kg-1 by the vena caudal once a week for 6 weeks. The rats in trimetazidine intervention group were intragastricly infused with trimetazidine 5.4 mg · kg-1 · d-1 one day for 8 weeks before making the model. At the end of the experiment,the malonaldehyde (MDA)level,nitrogen oxide (NO)level,superoxide dismutase(SOD)activity,and nonprotein sulfhydryl (NPSH)level in myocardium tissue were measured. The histological changes of myocardium tissue were detected by electron microscope. Results Compared with control group ,the levels of MDA and NO in pirarubicin group were increased(P<0.05), and the SOD activity and NPSH level in pirarubicin group were decreased(P<0.05).Compared with pirarubicin group,the levels of MDA and NO in trimetazidine intervention group were decreased(P<0.05),the SOD activity and NPSH level in trimetazidine intervention group were increased(P<0.05).Under electron microscope,the myocardiocytes of the rats in pirarubicin group showed irregular arrangement in sacromere structure, shrinkage in nuclear membrane, vacuolation in nuclear matrix, obvious mitochondria swelling, deposition of metachromatin throughout the nucleus,and an indistinct view of intercalated disc with isolation;while in trimetazidine intervention group the nucleus was round and nuclear membrane was indented,myofilament bundles were decreased slightly with a regular arrangement, intercalated disc oriented transversely with partial vague in cell j unction structure, and mitochondria slightly swelled.Conclusion Trimetazidine has the protective effects on the damaged myocardiocytes caused by pirarubicin,and its mechanism may be related to reducing the production of free radicals and decreasing the injury of structures within the cells,such as the nucleus,mitochondria and intercalated disc.