Objective:To develop a modified University of Wisconsin preservation solution (UW solution) containing α 2-adrenergic receptor agonists (dexmedetomidine) and noble gases (argon) and investigate its protective effect on the isolated amputated skeletal muscle of rats. Methods:Sixty male SD rats were selected to establish a hindlimb cold preservation/perfusion model and were divided into blank control group, hypothermic storage group, UW solution perfusion group, and modified UW solution perfusion group using a random number table, with 15 rats in each group. Simultaneously, a cold preservation model of rat skeletal muscle myoblasts (L6 cells) was established and the rats were also divided into four groups in the same way. Animal models were prepared in different ways: In the blank control group, the hindlimbs received no special treatment; In the hypothermic storage group, the amputated hindlimbs were stored in a dry centrifuge tube at 4℃ for 18 hours; In the UW solution perfusion group, the amputated hindlimbs were perfused with UW solution and then stored in a centrifuge tube containing UW solution at 4℃ for 18 hours; In the modified UW solution perfusion group, the amputated hindlimbs were perfused with modified UW solution (containing 0.1 nmol/L dexmedetomidine and 50% volume fraction of argon) and then stored in a centrifuge tube containing the modified UW solution at 4℃ for 18 hours. Cell models were treated as follows: In the blank control group, L6 cells were cultured under standard conditions; In the hypothermic storage group and UW solution group, L6 cells were treated with conventional culture medium or UW solution, stored in argon-filled sealed bags at 4℃ for 8 hours, and then rewarmed and cultured for 6 hours; In the modified UW solution group, L6 cells were treated with the modified solution, stored in argon-filled sealed bags at 4℃ for 8 hours, and then rewarmed and cultured for 6 hours. After sample collection, skeletal muscle morphology, tissue edema and ultrastructure features were assessed by HE staining, wet-to-dry weight ratio, and transmission electron microscopy, respectively. Additionally, L6 cell morphology was examined by light microscopy. L6 cell viability was determined by cell counting kit-8 (CCK-8) assay (expressed as absorbance A value). Expression levels of glutathione peroxidase 4 (GPX4) protein in both skeletal muscle tissue and L6 cells were evaluated by immunofluorescence staining and Western blot, respectively.Results:After 18 hours of in vitro preservation of rat isolated amputated limbs, the following results were obtained: (1) HE staining results showed that the muscle fiber morphology of the modified UW solution perfusion group was close to that of the blank control group. Moreover, the area ratio of skeletal muscle cells in the modified UW solution perfusion group was significantly higher than that in the hypothermic storage group and UW solution perfusion group ( P<0.05). (2) The wet-dry weight ratio results showed that there was no statistically significant difference among the modified UW solution perfusion group, the blank control group and UW solution group ( P>0.05), with significantly lower ratios in all three groups than that in the hypothermic storage group ( P<0.05). (3) Transmission electron microscopy results revealed that the modified UW solution perfusion group showed no statistically significant differences in ultrastructural metrics, including myofiber diameter, sarcomere length, mitochondrial short-axis/long-axis ratio, and mitochondrial cristae count, compared with those in the blank control group ( P>0.05), and performed significantly better than both the hypothermic storage group and UW solution perfusion group ( P<0.05). (4) Morphological observation of L6 cells showed that the cellular morphology was regular in the modified UW solution perfusion group, close to that in the blank control group, while it was severely damaged in the hypothermic storage group. Moreover, the cells were reduced in number and partially damaged in the UW solution group. The sequence of cell viability expressed as absorbance A value was blank control group >modified UW solution perfusion group > UW solution perfusion group > hypothermic storage group, with statistically significant differences among the four groups ( P<0.05). (5) Immunofluorescence staining showed that there was no statistically significant difference in fluorescence intensity of GPX4 protein expression between the modified UW solution perfusion group and blank control group ( P>0.05), while the fluorescence intensity was higher in the modified UW solution perfusion group than that in the hypothermic storage group and UW solution perfusion group ( P<0.05). Western blot analysis showed that the relative expression level of GPX4 in the modified UW solution group was significantly lower than that in the blank control group ( P<0.05), but higher than that in the hypothermic storage group and UW solution perfusion group ( P<0.05). Conclusion:The modified UW solution can stabilize the expression level of GPX4 protein, thereby inhibiting ferroptosis and alleviating cold preservation injury in both rat amputated isolated limb skeletal muscle tissue and L6 cells.

Objective:To develop a modified University of Wisconsin preservation solution (UW solution) containing α 2-adrenergic receptor agonists (dexmedetomidine) and noble gases (argon) and investigate its protective effect on the isolated amputated skeletal muscle of rats. Methods:Sixty male SD rats were selected to establish a hindlimb cold preservation/perfusion model and were divided into blank control group, hypothermic storage group, UW solution perfusion group, and modified UW solution perfusion group using a random number table, with 15 rats in each group. Simultaneously, a cold preservation model of rat skeletal muscle myoblasts (L6 cells) was established and the rats were also divided into four groups in the same way. Animal models were prepared in different ways: In the blank control group, the hindlimbs received no special treatment; In the hypothermic storage group, the amputated hindlimbs were stored in a dry centrifuge tube at 4℃ for 18 hours; In the UW solution perfusion group, the amputated hindlimbs were perfused with UW solution and then stored in a centrifuge tube containing UW solution at 4℃ for 18 hours; In the modified UW solution perfusion group, the amputated hindlimbs were perfused with modified UW solution (containing 0.1 nmol/L dexmedetomidine and 50% volume fraction of argon) and then stored in a centrifuge tube containing the modified UW solution at 4℃ for 18 hours. Cell models were treated as follows: In the blank control group, L6 cells were cultured under standard conditions; In the hypothermic storage group and UW solution group, L6 cells were treated with conventional culture medium or UW solution, stored in argon-filled sealed bags at 4℃ for 8 hours, and then rewarmed and cultured for 6 hours; In the modified UW solution group, L6 cells were treated with the modified solution, stored in argon-filled sealed bags at 4℃ for 8 hours, and then rewarmed and cultured for 6 hours. After sample collection, skeletal muscle morphology, tissue edema and ultrastructure features were assessed by HE staining, wet-to-dry weight ratio, and transmission electron microscopy, respectively. Additionally, L6 cell morphology was examined by light microscopy. L6 cell viability was determined by cell counting kit-8 (CCK-8) assay (expressed as absorbance A value). Expression levels of glutathione peroxidase 4 (GPX4) protein in both skeletal muscle tissue and L6 cells were evaluated by immunofluorescence staining and Western blot, respectively.Results:After 18 hours of in vitro preservation of rat isolated amputated limbs, the following results were obtained: (1) HE staining results showed that the muscle fiber morphology of the modified UW solution perfusion group was close to that of the blank control group. Moreover, the area ratio of skeletal muscle cells in the modified UW solution perfusion group was significantly higher than that in the hypothermic storage group and UW solution perfusion group ( P<0.05). (2) The wet-dry weight ratio results showed that there was no statistically significant difference among the modified UW solution perfusion group, the blank control group and UW solution group ( P>0.05), with significantly lower ratios in all three groups than that in the hypothermic storage group ( P<0.05). (3) Transmission electron microscopy results revealed that the modified UW solution perfusion group showed no statistically significant differences in ultrastructural metrics, including myofiber diameter, sarcomere length, mitochondrial short-axis/long-axis ratio, and mitochondrial cristae count, compared with those in the blank control group ( P>0.05), and performed significantly better than both the hypothermic storage group and UW solution perfusion group ( P<0.05). (4) Morphological observation of L6 cells showed that the cellular morphology was regular in the modified UW solution perfusion group, close to that in the blank control group, while it was severely damaged in the hypothermic storage group. Moreover, the cells were reduced in number and partially damaged in the UW solution group. The sequence of cell viability expressed as absorbance A value was blank control group >modified UW solution perfusion group > UW solution perfusion group > hypothermic storage group, with statistically significant differences among the four groups ( P<0.05). (5) Immunofluorescence staining showed that there was no statistically significant difference in fluorescence intensity of GPX4 protein expression between the modified UW solution perfusion group and blank control group ( P>0.05), while the fluorescence intensity was higher in the modified UW solution perfusion group than that in the hypothermic storage group and UW solution perfusion group ( P<0.05). Western blot analysis showed that the relative expression level of GPX4 in the modified UW solution group was significantly lower than that in the blank control group ( P<0.05), but higher than that in the hypothermic storage group and UW solution perfusion group ( P<0.05). Conclusion:The modified UW solution can stabilize the expression level of GPX4 protein, thereby inhibiting ferroptosis and alleviating cold preservation injury in both rat amputated isolated limb skeletal muscle tissue and L6 cells.

Objective:To investigate the risk factors and cumulative risk of myopia in children and adolescents, providing a basis for identifying cumulative risk factors in preventing and controlling myopia.Methods:Baseline data from the mental and physical health cohort of children and adolescents established in Inner Mongolia Autonomous Region were used. A stratified random cluster sampling method was adopted to select 138 974 students from fourth to twelfth grade as participants. Distance visual exams, refractive assessments, and questionnaires were conducted on the included students. Logistic regression analysis was used to evaluate each risk factor's impact on myopia's prevalence. The number of risk factors was summed to form a cumulative risk score, and logistic regression analysis was conducted to examine the association between the cumulative risk score and the prevalence of myopia. Additionally, the association between the cumulative risk score of myopic students and their degree of refractivity was analyzed using a generalized estimating equation.Results:The study found a high prevalence of myopia among children and adolescents at baseline (70.2%). Girls exhibited a higher prevalence (74.8%) than boys (65.6%), urban areas (74.3%) surpassed suburban ones (68.6%), and the incidence was greater in high schools (80.3%) compared to middle schools (75.3%), which, in turn, was higher than in elementary schools (57.7%) (all P<0.05). Analysis of risk factors revealed that children and adolescents experiencing improper reading and writing distances ( OR=1.10, 95% CI: 1.07-1.13), excessive homework ( OR=1.09, 95% CI: 1.06-1.12), insufficient sleep ( OR=1.10, 95% CI: 1.07-1.13), having myopic father ( OR=1.98, 95% CI: 1.91-2.05), having myopic mother ( OR=2.04, 95% CI: 1.97-2.10), or using classroom chairs not matched to their height faced ( OR=1.04, 95% CI: 1.01-1.07) increased myopia risks. Additionally, the prevalence and significant odds ratio of myopia increased with the increase in cumulative risk score, with every additional unit of cumulative risk score increasing the right eye's refractive error by -0.10 D. Conclusion:The presence of multiple factors and their comprehensive score increases the prevalence of myopia in children and adolescents.

Objective: To understand the early life factors that influence cardiometabolic risk factors in children and adolescents, so as to provide effective measures to curb cardiometabolic risk factors such as hypertension and diabetes in children and adolescents. Methods: Data were sourced from the 2020 follow up survey of the Xiamen Adolescent Development Cohort. The study involved 1 197 subjects for whom completed anthropometric examination and blood biochemistry testing data, as well as early life data. Early life and sociodemographic data were obtained through questionnaire surveys, while cardiometabolic indicator data were sourced through physical examinations and blood testing. Logistic regression analysis was performed to analyze the impact of early life factors on the cardiometabolic risk factors after adjusting for gender, age, and family history. Results: The prevalence rate of cardiometabolic risk factors clustering in children and adolescents in Xiamen was 17.96%, with boys (26.67%) reporting higher rates than girls (9.64%), and the difference was statistically significant ( χ 2=57.69, P <0.01). For every additional early life risk factor, the risk factors of obesity increased 0.35 times ( OR=1.35, 95%CI=1.03-1.78, P <0.05). Post term pregnancy may be a primary early life risk factors for cardiometabolic risk factors, and it was associated with an increased risk of cardiometabolic risk factors clustering (OR=2.45, 95% CI =1.11-5.41) and high triglycerides ( OR=3.25, 95%CI =1.39-7.61)( P <0.05). Conclusion Increased cardiometabolic risk factors in youth is associated with early life adverse factors. It is crucial to pay greater attention to post term pregnancy as an early life factor and to consider obesity as a cardiometabolic risk factors. Controlling early life adverse factors is important for the prevention of cardiovascular disease.

Objective: To understand the current status of obesity and high blood pressure (HBP) comorbidity and their multidimensional influencing factors in children aged 7-12 years in Xiamen, so as to provide reference basis for subsequent preventive measures. Methods: Based on the baseline survey of the Xiamen pubertal development cohort in 2017, a total of 4 798 primary school students from second to sixth grade were selected in the study by cluster random sampling method. And physical examination and questionnaires were conducted. The Logistic regression was used to screen potential variables for obesity combined with HBP. A multivariate Logistic regression model was used to analyse the factors influencing obesity combined with HBP. Results: About 9.15 % children were found with obesity and 11.65% with HBP. The rate of obesity combined with HBP was 3.00% in boys and 1.80 % in girls. The rate of HBP was 8.28% in normal weight children and 26.88% in obese children. Multivariate Logistic regression models showed that consumption of sugary drinks at least once a week ( OR =2.50), daily consumption of salted or pickled vegetables ( OR =4.52), family history of obesity ( OR =3.09) were positively associated with obesity combined with HBP ( P <0.05). Girls ( OR =0.53), consumption of highenergy snacks at least once a week ( OR =0.40) and adequate physical activity ( OR =0.58) were negatively associated with comorbidity of obesity and HBP ( P <0.05). Conclusion Gender differences in comorbidity burden of obesity and HBP exist among children aged 7-12 years in Xiamen. Dietary behaviour and exercise behaviour are the main dimensions influencing the comorbidity of obesity and HBP. Prevention and control of obesity and HBP in children should be based on multiple dimensions, including diet and exercise behavioural environment, to prevent early the occurrence for comorbidity of obesity and HBP in children.

Objective: To investigate the prevalence of Internet addiction and depression of students, and to analyze the co-occurrence and trend, so as to provide a theoretical basis for prevention and controlling measures of Internet addiction and depression. Methods: A total of 6 317,7 152,81 808,71 180 and 89 932 students aged 10 to 24 years from 12 leagues (103 banners) in Inner Mongolia Autonomous Region were selected by stratified random cluster sampling in September each year from 2017 to 2021. The Internet Addiction Scale and the Central for Epidemiologic Studies Depression Scale(CES-D) was used to measure Internet addiction and depression. And the annual inspection rate, group difference and annual change trend in students were calculated. Multivariate linear regression and restricted cubic spline analysis were used to estimate the linear and non linear associations between Internet addiction and depression in students. Results: The Internet addiction proportion in students gradually decreased from 4.1% in 2017 to 2.1% in 2020, but increased to 3.9% in 2021. And the depressive symptoms proportion increased from 20.9% in 2017 to 28.0% in 2020 and 27.0% in 2021. The detection rate of Internet addiction and depression comorbidities remained at 1.8% to 2.5 %. The Internet addiction proportion in boys was higher than that in girls( χ 2=42.82， P <0.05). The depressive symptoms prevalence in girls was higher than that in boys( χ 2= 553.90， P <0.05). Taking reversal in prevalence of Internet addiction in urban and rural areas was observed in 2019. The detection rates of depressive symptoms and comorbidity were higher in urban areas than these in suburban counties on the whole, and the difference showed a trend of decreasing or even equalizing year by year. Internet addiction was positively correlated with depressive symptoms score ( B=1.67, 95%CI =1.64-1.71), the proportion of depressive symptoms ( OR=1.39, 95%CI =1.38-1.41) and the proportion of major depressive symptoms ( OR=1.35, 95%CI =1.33-1.36) among students in 2021 ( P <0.05). An N-shaped curve was found in the significant nonlinear associations between internet addiction and depression across sex, region and school stage. Conclusion Internet addiction and depression in students show significant linear and non-linear associations, which are consistent in different sexes, regions and school stages. Therefore, relevant measures should be made and implemented in each region, especially in suburb areas, so as to prevent the increasingly development of adolescents and children s Internet addiction and depression.

Objective: To explore the association between digital devices usage and body weight overestimation in children and adolescents aged 7-18, in order to provide a scientific basis for body weight overestimation prevention in children and adolescents. Methods: Based on the data of the Research Special Project for Public Welfare Industry of Health using stratified cluster sampling method in 2012, a tatal of 40 073 children and adolescents from 7 provinces with complete information were chosen. Ordinal multivariable Logistic regression model estimated the association between digital devices usage and body weight overestimation. Results: A total of 4 276(11.8%) students with overestimation of body weight were detected, who spent >300 min/d time in digital devices(5.12%) than others (3.84%)( χ 2=19.14, P <0.01). Univariate analysis showed that students with time spent on digital devices >300 min/d had a higher risk in overestimation of body weight ( OR=1.36,95%CI=1.18-1.57,P <0.01) compared with students who spent on digital devices≤120 min/d. There was still a significant association after confounder adjustment ( OR=1.28, 95%CI= 1.10-1.48,P <0.05). Stratified analysis showed that the association between digital devices usage and overestimation of body weight were only observed in girls, 11-18 years old and non single child( P <0.05). Conclusion The time usage of digital devices is associated with overestimation of body weight in children and adolescents. It may helpful for children and adolescents to prevent overestimation of body weight by reducing time spent on digital devices.

Objective:To analyze the association between overweight and obesity, psychological distress, and the influence of physical exercise among Chinese children and adolescents.Methods:The study used data from the 2019 Chinese National Survey on Students' Constitution and Health. A total of 95 280 Han Chinese children and adolescents aged 13 to 18 years were included in the study based on complete information on overweight and obesity, psychological distress assessment, and physical exercise variables. The Kessler Psychological Distress Scale was used to measure their psychological distress, with scores above 25 indicating high psychological distress. The BMI group of the adolescents was evaluated according to the Chinese standard "WS/T 586-2018 Screening for Overweight and Obesity in School-age Children and Adolescents", including underweight, normal weight, overweight, and obesity. The individual's BMI Z-score (BMIZ) was evaluated using the WHO standard and divided into ten groups based on the population percentile distribution. The survey collected the subjects' average daily physical exercise time and divided them into two groups: less than 1 hour and greater than or equal to 1 hour. Logistic regression analysis was used to analyze the relationship between overweight and obesity and high psychological distress among children and adolescents and the differences in association between different physical exercise groups.Results:The detection rates of overweight and obesity among Han Chinese children and adolescents aged 13 to 18 years in 2019 were 14.5%, and 7.6%, respectively. The rate of high psychological distress was 37.6%, and the rate of average daily physical exercise time exceeding 1 hour was 17.1%. Using the population with a BMIZ P10 below as a reference, the association strength between high psychological distress and the population gradually increased, with an OR (95% CI) value of 1.08 (1.02-1.14), 1.09 (1.02-1.14), 1.10 (1.03-1.16), and 1.16 (1.09-1.23) for BMIZ in the P60-, P70-, P80-, > P90 groups. Compared to normal weight, both overweight and obesity were positively associated with high psychological distress in children and adolescents, with obesity showing a more significant correlation, while underweight was negatively associated with high psychological distress. The detection rates of high psychological distress in normal weight, underweight, overweight, and obese groups were 37.6%, 37.0%, 38.2%, and 38.7%, respectively, with an OR (95% CI) value of 0.93 (0.88-0.98) for the underweight group and 1.05 (1.01-1.10) and 1.13 (1.07-1.19) for the overweight and obese groups, respectively. The positive correlation between BMIZ, overweight, and obesity with high psychological distress was significant only in adolescents who exercised less than 1 hour per day on average. Conclusions:Chinese children and adolescents face the problem of obesity and high psychological distress, with a positive correlation between these two problems. Physical activity may moderate the association between obesity and psychological distress in children and adolescents. Adequate physical exercise may offset the potential high psychological distress caused by obesity in children and adolescents. Thus, strengthening physical exercise among children and adolescents reduces the risks of both obesity and psychological health problems effectively.

Objective:To evaluate the level of psychological distress among Chinese children and adolescents and analyze its lifestyle influencing factors.Methods:Data were obtained from the 2019 Chinese National Survey on Students' Constitution and Health. A lotal of 120 285 Han Chinese children and adolescents aged 9-18 years with complete information on the psychological distress scale and lifestyle factors were selected, including 58 432 boys and 61 853 girls. The Kessler Psychological Distress Scale (K10) measured psychological distress, and lifestyles such as physical activity, sedentary behavior, diet, and sleep were also investigated. K10 scores of different genders were compared using the t-test, and the levels of psychological distress were compared using the χ2 test. Logistic regression was used to analyze lifestyle risk factors associated with high psychological distress, and multiple linear regression was used to find the relationship between K10 scores and lifestyle scores. Results:The average K10 score for Han Chinese children and adolescents aged 9-18 years was 21.25±7.35, with girls (21.43±7.35) scoring higher than boys (21.06±7.36), the difference was statistically significant ( t=8.72, P<0.001). The rate of high psychological distress was 29.81%, with girls (31.08%) reporting higher rates than boys (28.46%), the difference was statistically significant ( χ2=98.54, P<0.001). 56.10% of children and adolescents have unhealthy lifestyles, with girls (58.77%) reporting higher rates than boys (53.27%), the difference was statistically significant ( χ2=368.53, P<0.001). Except for insufficient outdoor activities for girls ( P=0.128), lifestyles such as insufficient physical activity, insufficient muscle-and-bone exercises, long screen time, not eating breakfast, eggs and dairy products every day, drinking sugary beverages once or more per day, and not having enough sleep are all risk factors for high psychological distress (all P<0.001). For every additional healthy lifestyle score, the K10 score decreased by 0.98 [ β=-0.98 (95% CI: -1.01- -0.95)] points ( P<0.001). K10 scores in each region negatively correlate with lifestyle scores (all P<0.001). Among them, the K10 score in the eastern region showed the slightest decrease as the lifestyle score increased, while the western region showed the most decrease. Conclusions:The prevalence of psychological distress and unhealthy lifestyle in Chinese children and adolescents are high and interrelated. Compared those with healthy lifestyles, children and adolescents with unhealthy lifestyles are at greater risk of high psychological distress. Therefore, promoting healthy lifestyles for children and adolescents may be one of the important ways to improve their mental health.

Objective:To analyze the association between exposure to ambient PM 2.5 and its components [sulfate (SO 42-), nitrate (NO 3-), ammonium (NH 4+), organic matter (OM), and black carbon (BC)] and psychological distress among school children and adolescents aged 9 to 18 years in China. Methods:Based on data from the 2019 Chinese National Survey on Students' Constitution and Health, 130 808 children and adolescents aged 9 to 18 years were included. Scoring and determination of higher psychological distress were based on the Kessler Psychological Distress Scale (K10), and annual average exposure data for air pollution were matched by survey location and time. We used a restricted cubic spline approach based on logistic regression to fit the associations between PM 2.5, SO 42-, NO 3-, NH 4+, organic matter, black carbon concentrations, and psychological distress. Logistic regression models were used to analyse different age, gender, BMI and physical activity subgroups to estimate the association between exposure to high levels of pollution and high levels of psychological distress in different subgroups. Results:The proportion of children and adolescents with high levels of psychological distress in China was 30.4%, with girls being higher than boys at 31.6% and 29.1%, respectively ( P<0.05). A non-linear positive association existed between exposure to PM 2.5, SO 42-, NO 3- and organic matter concentrations and higher psychological distress. As PM 2.5, NO 3-, NH 4+, organic matter, and black carbon concentrations continued to rise, the increase in the risk of higher psychological distress slowed, while SO 42- showed little change in the OR of psychological distress at lower concentrations but continued to rise at higher concentrations. PM 2.5 and its components were statistically associated with psychological distress in the physically inactive group but not in the physically active group. The association between high levels of pollutants and high psychological distress was stronger among students aged 9 to 12 years compared with students aged 13 to 15 years and 16 to 18 years. Conclusions:The ambient pollutant PM 2.5 and its components are associated with psychological distress in children and adolescents aged 9 to 18 years in China. High pollutant exposure is a risk factor for high psychological distress among physically inactive children and adolescents, and there are age differences in the association between PM 2.5 and components and psychological distress.