Study on relationship between outdoor activities and self-reported myopia among middle school students / 中华预防医学杂志

Objective@#To examine the relationship between the prevalence of self-reported myopia and outdoor activities among middle school students and to explore the influence factors of the self-reported myopia.@*Methods@#A total of 12 979 participants were recruited from junior and senior middle school students in in Shenzhen, Nanchang, Zhengzhou and Shenyang by random cluster sampling method between December 2015 and March 2016. All participants completed an anonymous questionnaire to collect the information of demographic characteristics, self-reported myopia, outdoor activities, etc. 12 603 out of 12 979 copies of questionnaire were valid. The prevalence of self-reported myopia was compared among middle school students with different characteristics. Logistic regression models were used to analyze the relationship between myopia and outdoor activities.@*Results@#The prevalence of self-reported myopia among middle school students was 69.6% (8 766/12 603); which was separately 52.1% (1 216/2 335) in seventh grader, 61.6% (1 459/2 369) in eighth grader, 69.0%(1 470/2 129) in ninth grader, 80.0% (1 812/2 265) in freshmen, 79.4% (1 622/2 042) in sophomore, and 81.1%(1 187/1 463) in junior. The prevalence of self-reported myopia showed an increasing trend with the increase of grade (χ2=639.67, P<0.001). The prevalence of self-reported myopia was separately 63.5%(4 927/7 756) in non-myopic parents group, 78.0%(2 664/3 415)in either myopic parent group, and 82.1%(1 175/1 432) in both myopic parents group(χ2=328.28, P<0.001). Outdoor activities were associated with self-reported myopia. Binary logistic regression analysis showed that the risk of self-reported myopia was significantly increased by always staying at home in extracurricular time among the middle school students (OR=1.58, 95%CI: 1.36-1.82). The risk of self-reported myopia were significantly decreased by always physical exercise and recreational activities after school among middle school students: the ORs were separately 0.67 (95%CI: 0.57-0.78) for physical exercise and 0.77 (95%CI: 0.64-0.92) for recreational activities. After stratified analysis by the parents' myopia status, in non-myopic parents group, exercise and recreational activities after school among middle school students decreased the risk of myopia: the ORs were separately 0.68 (95%CI: 0.55-0.82) for physical exercise and 0.76 (95%CI: 0.61-0.95) for recreational activities; in either myopic parent group, OR(95%CI) were separately 0.65 (0.47-0.90) and 0.68 (0.47-0.98).@*Conclusion@#Outdoor activities was negatively associated with self-reported myopia among middle school students. However, the parents' myopia status may affect the protective effect.

Investigation of influencing factors associated with neck-shoulder symptoms among middle school students in three cities in China / 中华预防医学杂志

Objective@#The aim of this study was to describe the distribution of neck-shoulder symptoms among middle school students, and to explore its influence factors.@*Methods@#A cross-sectional survey was conducted on 24 middle schools in Shenyang, Zhengzhou and Shenzhen by purposive sampling method. In each middle school, 3 to 4 classes were selected from each grade all the students in the selected class would be recruited to the survey to investigate the demographic characteristics, neck-shoulder symptoms, physical exercise time, academic stress, screen behavior, sedentary behavior and other information by questionnaire. A total of 10 566 questionnaires were issued and 10 270 valid questionnaires were withdrawn. The prevalence of neck-shoulder symptoms among students were compared by different characteristics. Logistic regression models were applied to examine influencing factors associated with neck-shoulder symptoms.@*Results@#The prevalence of neck-shoulder symptoms among middle school students was 19.2% (1 968/10 270), while it was 22.6% (1 137/5 039) among girls and 15.9% (831/5 231) among boys; the difference showed statistical significance (P<0.001). The prevalence of neck-shoulder symptoms was separately 13.3% (253/1 901) in seventh grade, 16.8% (326/1 942) in eighth grade, 18.5% (299/1 617) in ninth grade, 21.8% (417/1 915) in sophomore, 21.4% (345/1 611) in junior, 25.5% (328/1 284) in senior; the difference showed statistical significance (P<0.001). The multivariate logistic regression analysis showed that in the last 3 months, students who always playing mobile phone ≥40 min continuously (OR=4.66, 95%CI: 3.95-5.49), watching TV ≥40 min continuously (OR=4.01, 95%CI: 3.39-4.73), using computer ≥40 min continuously (OR=3.61, 95%CI: 3.09-4.23), doing homework ≥60 min continuously (OR=3.25, 95%CI: 2.79-3.79), the average daily sitting time ≥10 h (OR=4.95, 95%CI: 4.25-5.77), and always sitting ≥90 min continuously (OR=5.18, 95%CI: 4.42-6.06) were risk factors of neck-shoulder symptoms.@*Conclusion@#The prevalence of neck-shoulder symptoms was high among middle school students in China, especially girls in senior grades. Long time, high frequency video behaviors and sedentary behaviors were related to the occurrence of neck-shoulder symptoms among middle school students.

Progress in research of association between myopia and sunlight exposure in children / 中华流行病学杂志

Myopia has become a major health problem on global scale due to its increasing high prevalence in the past few decades and gradual younger onset age.Accumulated epidemiological surveys have shown that decreased time of exposure to sunlight would be an inducement for the development of myopia.Increasing time spent outdoors and exposure to sunlight might be the most cost-effective and effective measure for children to prevent myopia.This paper summarizes the progress in research of the association between sunlight exposure and myopia in children and its mechanisms to provide new clues for the research on myopia prevention and control.

Progress in research of association between myopia and sunlight exposure in children / 中华流行病学杂志

Myopia has become a major health problem on global scale due to its increasing high prevalence in the past few decades and gradual younger onset age.Accumulated epidemiological surveys have shown that decreased time of exposure to sunlight would be an inducement for the development of myopia.Increasing time spent outdoors and exposure to sunlight might be the most cost-effective and effective measure for children to prevent myopia.This paper summarizes the progress in research of the association between sunlight exposure and myopia in children and its mechanisms to provide new clues for the research on myopia prevention and control.

[Establishment of a miniature pig model of mandibular osteoradionecrosis].

OBJECTIVE: To establish a miniature pig model of mandibular osteoradionecrosis (ORN). METHODS: A single dose of irradiation (IR25 Gy, 28 Gy) was delivered via an electronic linear accelerator to the right mandible of 24 miniature pigs by utilizing three dimensional conformal radiotherapy (3D-CRT). The first molar of the mandible was extracted 2 months after radiation. Mandibular ORN was diagnosed through gross observation, X-ray film, CT, and histopathologic examination. RESULTS: At 3-4 months after radiation, all animals suffered from mandibular ORN after dental extraction. The symptoms of ORN were more severe in the 28 Gy group than in the 25 Gy group. CONCLUSION: A miniature pig model of mandibular ORN can be established through 25 Gy irradiation + dental extraction.

Establishment of a miniature pig model of mandibular osteoradionecrosis / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To establish a miniature pig model of mandibular osteoradionecrosis (ORN).</p><p><b>METHODS</b>A single dose of irradiation (IR25 Gy, 28 Gy) was delivered via an electronic linear accelerator to the right mandible of 24 miniature pigs by utilizing three dimensional conformal radiotherapy (3D-CRT). The first molar of the mandible was extracted 2 months after radiation. Mandibular ORN was diagnosed through gross observation, X-ray film, CT, and histopathologic examination.</p><p><b>RESULTS</b>At 3-4 months after radiation, all animals suffered from mandibular ORN after dental extraction. The symptoms of ORN were more severe in the 28 Gy group than in the 25 Gy group.</p><p><b>CONCLUSION</b>A miniature pig model of mandibular ORN can be established through 25 Gy irradiation + dental extraction.</p>

Preliminary study on treatment of mandibular osteoradionecrosis by autologous bone marrow mesenchymal stem cells in miniature pigs / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the treatment effect of mandibular osteoradionecrosis (ORN) by autologous bone marrow mesenchymal stem cells (BMMSC) in miniature pigs.</p><p><b>METHODS</b>Six miniature pigs with mandibular ORN (25 Gy) were used. BMMSC were separated and cultured in vitro and then implanted on to the premolded hydroxyapatite-tricalcium phosphate (HA-TCP). The BMMSC-HA-TCP complexes were implanted into the defective area of mandibular ORN in 4 animals. Implantation of only HA-TCP in 2 animals served as control. Gross observation, spiral CT, coronary CT and histopathologic examination were carried out.</p><p><b>RESULTS</b>Fistula disappeared in animals with BMMSC-HA-TCP complexes 3 months after implantation, while fistula was found in controls. Spiral CT analysis showed that cortical bone repair were found 4 months after BMMSC-HA-TCP complexes implantation, while bone damage (cortical and cancellous bone fracture) increased in controls. Histopathologic examination revealed that 4 months later after BMMSC-HA-TCP complexes implantation, new bone formation and bone cells could be observed, but there was a large number of fibrous tissue and no new bone in controls.</p><p><b>CONCLUSIONS</b>Transplantation of autologous BMMSC with HA-TCP may have therapeutic effect in the treatment of mandibular ORN.</p>