Background A large number of power supply workers are involved in live working and are exposed to multiple risk factors for long periods of time during outdoor work, which in turn causes occupational health problems. Objective To identify potential ergonomic factors related to work-related musculoskeletal disorders (WMSDs) and estimate the ergonomic risk of electricians. Methods A total of 31 workers were randomly selected from a training base under a power supply enterprise in Guangxi, and their operation processes were recorded by video. Using the Rapid Upper Limb Assessment (RULA) method, the workers were scored by the posture of their arms, neck, and torso during operation, and the final scores were summarized to assess their risk level. Two independent samples t-tests were used to compare the differences in RULA scores. Results A total of 31 videos for mounting/dismounting insulation mask and 29 videos for breaking/connecting contact terminal were collected. The RULA score for mounting/dismounting insulation mask was 6.6 ± 0.7 (left side) and 7.0 ± 0.2 (right side), most of the workers had a score of 7 (71.0% on the left side and 96.8% on the right side), and the upper limb and overall scores on the right side were higher than those on the left side (P < 0.05). The RULA score for breaking/connecting contact terminal was 6.9 ± 0.4 (both right and left sides), most of workers had a score of 7 (89.7% on the left side and 93.1% on the right side), and the difference of the overall scores between the right and left side for this operation were not statistically significant (P > 0.05). The ergonomic risk levels for both operations were level 3 or higher. Conclusion Mounting/dismounting insulation mask and breaking/connecting contact terminal are typical upper limb operations, and have a high level of ergonomics risk, requiring effective preventive and protective measures.

To evaluate the advantages of using PBL case library in teaching circulatory system diseases to clinical medicine undergraduate students, a PBL case library was established and applied in teaching practice in the reform of circulatory system teaching. The PBL case library achieved the characteristics of combining theories with cases, morphology with functions, and basic knowledge with clinical knowledge. The PBL case library also realized the informatization, query, and update of cases. Preliminary application showed that the median practical score of students in the case library group was 94.00 points, which was significantly higher than the 92.00 points in the control group ( P=0.005). The average lesson preparation time for teachers in the case library group was (5.00±1.00) hours, which was significantly shorter than the (6.89±0.42) hours in the control group ( P<0.001). The difficulty score for lesson preparation among teachers in the case library group was significantly lower than that of the control group [(1.89±1.05) vs. (3.22±0.44), P<0.001]. However, there were no significant difference in theoretical scores and student satisfaction with teachers and courses. These results suggest that the construction of case library can improve practical teaching effectiveness and enhance the efficiency of lesson preparation for teachers.

Objective To analyze the correlation between thromboelastogram indicators(R time,K time,MA value)and global registry of acute coronary events(GRACE)score and acute myocardial infarction(AMI),and explore the risk factors for the onset of AMI.Methods A total of 108 patients with AMI who were hospitalized in Xuancheng Central Hospital for the first time from September 2020 to February 2023 were selected as the observation group,while 70 patients with stable coronary heart disease were selected as the control group.The clinical basic data,thromboelastogram indicators,GRACE score,and homocysteine(Hcy)of all study subjects were collected.The differences of clinical basic data,thromboelastogram indica-tors,GEACE score,and Hcy level between the observation group and the control group were statistically ana-lyzed.The predictive value of thromboelastogram indicators,GRACE score,and Hcy level for the occurrence of AMI was evaluated by using the receiver operating characteristic(ROC)curve.Binary Logistic regression model was used to conduct univariate and multivariate regression analyses on indicators with statistically sig-nificant differences,in order to determine the independent risk factors for AMI occurrence.Results There were significant differences of R time,K time,MA value,GRACE score,serum Hcy level,and the proportion of underlying diseases between the observation group and the control group(P＜0.05).The ROC curve re-sults showed that R time,K time,MA value,GRACE score,and Hcy had good predictive value for the occur-rence of different types of AMI,and the value of the combined application was higher.Univariate Logistic re-gression showed that MA value,GRACE score,Hcy level,and underlying disease were positively correlated with the occurrence of AMI(P＜0.05),while R time and K time were negatively correlated with the occur-rence of AMI(P＜0.05).Multivariate Logistic regression showed that high GRACE score and elevated Hcy level were independent risk factors for the occurrence of AMI(P＜0.05),while R time and K time were inde-pendent protective factors for the occurrence of AMI(P＜0.05).Conclusion Thromboelastogram,Hcy,and GRACE score could be used as dynamic monitoring indicators for clinical risk assessment of AMI in acute cor-onary syndrome population.

Malocclusion,identified by the World Health Organization(WHO)as one of three major oral diseases,profoundly impacts the dental-maxillofacial functions,facial esthetics,and long-term development of～260 million children in China.Beyond its physical manifestations,malocclusion also significantly influences the psycho-social well-being of these children.Timely intervention in malocclusion can foster an environment conducive to dental-maxillofacial development and substantially decrease the incidence of malocclusion or reduce the severity and complexity of malocclusion in the permanent dentition,by mitigating the negative impact of abnormal environmental influences on the growth.Early orthodontic treatment encompasses accurate identification and treatment of dental and maxillofacial morphological and functional abnormalities during various stages of dental-maxillofacial development,ranging from fetal stages to the early permanent dentition phase.From an economic and societal standpoint,the urgency for effective early orthodontic treatments for malocclusions in childhood cannot be overstated,underlining its profound practical and social importance.This consensus paper discusses the characteristics and the detrimental effects of malocclusion in children,emphasizing critical need for early treatment.It elaborates on corresponding core principles and fundamental approaches in early orthodontics,proposing comprehensive guidance for preventive and interceptive orthodontic treatment,serving as a reference for clinicians engaged in early orthodontic treatment.

Objective To investigate the value of a nomogram model based on contrast-enhanced CT radiomics in predicting the histological type of thymoma.Methods A total of 154 patients(101 in low-risk group and 53 in high-risk group)with thymoma confirmed by pathology were retrospectively selected.The cases were randomly divided into training set(n=107)and validation set(n=47)at a ratio of 7∶3.The three-dimensional volume of interest(VOI)of the whole lesion on the image from the arterial phase of contrast-enhanced CT was manually delineated,and the radiomics features were extracted.Based on the selected radiomics features,the radiomics model was constructed and the model Radiomics score(Radscore)was calculated.Clinical risk factors were screened to construct a clinical model,and a nomogram model was constructed by fusing Radscore and clinical risk factors.The receiver operating characteristic(ROC)curve,area under the curve(AUC),accuracy,sensitivity and specificity were compared to analyze the predictive efficacy and difference of different models for high-risk and low-risk thymoma.The decision curve and calibration curve were drawn to evaluate the clinical value and fitting performance of the nomogram model.Results Eleven radiomics features were selected to construct the radiomics model,and five clinical risk factors[myasthenia gravis(MG),morphology,border,surrounding tissue invasion and CT value in arterial phase]were used to construct the clinical model.In the training set,the AUC of the nomogram model(0.88)was higher than that of the radiomics model(0.80)and the clinical model(0.79),and the difference was statistically significant(Z=2.233,2.713,P=0.026,0.007,respectively).In the validation set,the AUC of the nomogram model was higher than that of the radiomics and clinical models,but the difference was not statistically significant.The calibration curve showed that the nomogram model had good fitting performance,and the decision curve showed that the nomogram model had high clinical benefit.Conclusion The nomogram model based on contrast-enhanced CT can effectively predict high-risk and low-risk thymoma,which is helpful to guide clinicians to make relevant decisions.

Background Operation and maintenance work in the power grid industry often involving climbing, manual handling, and poor postures causing serious problems like work-related musculoskeletal disorders (WMSDs). The influencing factors of WMSDs are not very clear, but the problem has been widely concerned in this industry. Objective To understand the prevalence and influencing factors of WMSDs among climbing task-involved workers in power supply enterprises. Methods Using a cross-sectional design, a total of 702 workers involving climbing task from 10 power supply enterprises in Jilin Province, Tianjin Municipality, and Shandong province were selected as study subjects using cluster sampling. The Musculoskeletal Disorders Questionnaire which was revised by Lei Yang was used to estimate the prevalence and identify related factors of WMSDs. \begin{document}$ {\chi ^2} $\end{document} test and multiple logistic regression were used to analyze the data. Results A total of 702 subjects were approached, 649 valid questionnaires were recovered, and the effective recovery rate was 92.45%. The prevalence of WMSDs was 81.2%, and neck (65.0%), low back (59.0%), and shoulders (54.4%) were areas of high prevalence of WMSDs. The multiple logistic regression analysis results showed that sometimes and often/very often holding awkward postures were the risk factors of neck, shoulders, low back, knees, upper back, hands/wrists, ankles/feet, elbows, and hips/thighs WMSDs; the OR (95%CI) values were 1.931 (1.260-2.959) and 3.145 (1.810-15.465), 2.700 (1.694-4.305) and 3.888 (2.224-6.798), 1.860 (1.213-2.852) and 3.150 (1.833-5.414), 2.348 (1.456-3.785) and 3.689 (2.130-6.388), 1.782 (1.128-2.815) and 3.274 (1.935-5.538), 1.710 (1.014-2.884) and 2.595 (1.455-4.630), 1.836 (1.019-3.305) and 2.860 (1.526-5.358), 2.250 (1.185-4.275) and 3.032 (1.505-6.108), 2.080 (1.048-4.128) and 3.127 (1.501-6.516), respectively. Department staff shortage was the risk factor of neck, shoulders, low back, upper back, hands/wrists, and ankles/feet WMSDs; the OR (95%CI) values were 1.791 (1.038-3.093), 2.000 (1.119-3.573), 2.506 (1.429-4.394), 2.063 (1.113-3.822), 2.256 (1.069-4.762), and 2.699 (1.103-6.601), respectively. Frequent knee bending was the risk factor of knees, upper back, and hands/wrists WMSDs; the OR (95%CI) values were 1.895 (1.327-2.704), 1.586 (1.131-2.224), and 2.026 (1.390-2.951), respectively. Often pushing/pulling heavy objects was the risk factor of shoulders, low back, and hips/thighs WMSDs; the OR (95%CI) values were 1.485 (1.066-2.192), 1.547 (1.064-2.749), and 1.822 (1.160-2.862), respectively. Long-time heavily neck tilting forward was the risk factor of elbows and hips/thighs WMSDs; the OR (95%CI) values were 1.649 (1.068-2.546) and 2.005 (1.285-3.129) respectively. Long-time ankle or foot bending was the risk factor of ankles/feet and elbows WMSDs; the OR (95%CI) values were 2.481 (1.685-3.655) and 1.655 (1.065-2.571) respectively. Cold or changes in temperature was the risk factor of neck and shoulders WMSDs; the OR (95%CI) values were 2.182 (1.072-4.443) and 2.116 (1.010-4.431) respectively. Exercise was the protective factor of neck, shoulders, low back, upper back, and ankles/feet WMSDs; the OR (95%CI) values were 0.493 (0.363-0.666), 0.625 (0.438-0.888), 0.404 (0.283-0.576), 0.570 (0.408-0.797), and 0.639 (0.436-0.937), respectively. Conclusion The prevalence of WMSDs is high among workers involving climbing task in power supply enterprises, and neck, low back, and shoulders are the most commonly affected body parts. The influencing factors involve awkward postures, repetitive movements, repetitive tasks, pushing/pulling heavy objects, staff shortage, poor working environment, and exercise.

Background Power grid is a basic industry of national economy. The occupational health problems among operation and maintenance workers in this industry have become increasingly prominent in recent years, and they should receive enough attention. Objective To estimate the prevalence of work-related musculoskeletal disorders (WMSDs) of neck and shoulder among operation and maintenance workers of power supply enterprises, and analyze related influencing factors. Methods From March to June 2021, a total of 1433 operation and maintenance worker from 10 power supply enterprises in three provinces of North China were selected as research subjects using cluster sampling method. A revised Musculoskeletal Disorders Questionnaire was used to investigate the prevalence and ergonomic factors of neck and shoulder pain in the past year. χ² test and logistic regression model were used to explore influencing factors of neck and shoulder pain among operation and maintenance workers. Results A total of 1343 valid questionnaires were recovered and the effective recovery rate was 93.72%. The neck pain prevalence was 66.0% (886 cases) and the shoulder pain prevalence was 54.1% (727 cases). The multiple logistic regression analysis results showed that often/very often long-time sitting (OR=1.864, 95%CI: 1.236-2.811; OR=1.659, 95%CI: 1.091-2.524), sometimes holding awkward postures (OR=1.695, 95%CI: 1.294-2.219; OR=1.596, 95%CI: 1.218-2.092), often/very often holding awkward postures (OR=2.416, 95%CI: 1.618-3.607; OR=2.058, 95%CI: 1.405-3.015), long-time slight neck tilting forward (OR=1.327, 95%CI: 1.023-1.722; OR=1.571, 95%CI: 1.221-2.022), long-time elbows bending (OR=1.327, 95%CI: 1.023-1.722; OR=1.506, 95%CI: 1.112-2.040) and department or team staff shortages (OR=1.578, 95%CI: 1.153-2.161; OR=1.831, 95%CI: 1.320-2.539) were associated with higher neck and shoulder pain prevalence rates. While exercise (OR=0.630, 95%CI: 0.492-0.809; OR=0.707, 95%CI: 0.557-0.899) was associated with lower neck and shoulder pain prevalence rates. Doing same work every day (OR=1.704, 95%CI: 1.305-2.225) was associated with a higher neck pain prevalence rate. Awkward postures with ineffectual force (OR=1.808, 95%CI: 1.226-2.665) and often keeping arms above shoulders (OR=1.424, 95%CI: 1.017-1.992) were associated with a higher shoulder pain prevalence rate. Conclusion The prevalence rates of neck and shoulder pian are high among operation and maintenance workers of power supply enterprises in selected three provinces of North China, and the main associated factors include individual factors, awkward work postures, and labor organization.

Background Long working hours is harmful to the physical and mental health of occupational groups, and should receive active attention. Objective To evaluate the current status of long working hours among operation and maintenance workers of power supply enterprises, and explore its effects on work-related musculoskeletal disorders (WMSDs) of the population. Methods From March to June 2021, a cross-sectional survey was conducted among 1433 operation and maintenance workers from 10 power supply enterprises in Jilin Province, Shandong Province, and Tianjin Municipality using cluster sampling. A total of 1433 copies of revised Mus-culoskeletal Disorders Questionnaire were distributed, 1343 questionnaires were recovered, and the recovery rate was 93.72%. The questionnaire included general information, personal health behaviors, weekly working hours, work-related factors, and musculoskeletal pain or discomfort in nine body parts in the past 12 months. χ² test and multiple logistic regression models were used to investigate the relationships between long working hours (>40 h per week) and WMSDs. Results The average age of the workers was (39.42±9.89) years, and the average work experience was 11.00 (5.00, 21.00) years. There were 1158 males (86.22%) and 185 females (13.78%). The average weekly working hours of the workers were (47.98±11.35) h, and the proportion of long working hours (>40 h per week) was 61.06% (820/1343). The proportions of long working hours were higher among the workers with characteristics of male, power distribution, shift work, often/very often long-time standing, often/very often holding awkward postures, often handling heavy objects, limited space to operate, long-time neck tilting backward, keeping arms above shoulders, frequent elbow bending, repeating knee movement every minute, and repeating lower limb or foot movement every minute (all P<0.05). The prevalence rate of WMSDs was 81.53% (1095/1343) among the workers. The results of multiple logistic regression showed that after adjusting education, smoking, exercise, awkward postures, often handling heavy objects, limited space to operate, long-time heavy trunk bending, long-time neck tilting backward, and keeping arms above shoulders, compared with working ≤40 h per week, the risk of WMSDs among workers working >49 h per week was higher (OR=1.406, 95%CI: 1.011-1.955). Conclusion Long working hours is prominent among operation and maintenance workers of power supply enterprises, and increases the risk of reporting WMSDs.

Background Climbing pylons during high-voltage cable maintenance is not only a labor-intensive task, but also a challenge bringing about heat stress and mental pressure from working at height, which may lead to accumulation of muscle fatigue and work-related musculoskeletal disorders. Objective To record the local muscle fatigue during a simulated climbing task by high-voltage cable electricians based on surface electromyography (sEMG) signals, explore the characteristic changes in sEMG signals and their relationship with subjective fatigue evaluation of the task, and provide data support for developing task specific objective assessment tools for local muscle fatigue and prevention of work-related musculoskeletal disorders. Methods Ten male college students were recruited to conduct a test of a simulated pylon climbing task. The climbing distance was 60 m, and a task segment was set for every 20 m (about 100 s), recorded as T1, T2, and T3, respectively. After completing each task segment, the subjects were required to rate their subjective fatigue using the Borg's RPE Scale. Fatigue was defined by rating of perceived exertion (RPE) score ≥ 14 in this study. The sEMG signals of trapezius, erector spinae, rectus femoris, and gastrocnemius muscles were recorded wirelessly. The standardized maximal voluntary electrical activation (MVE) obtained by standardizing the root mean square (RMS) of the time domain index and the median frequency (MF) of the frequency domain index were estimated for the recorded sEMG signals, and joint amplitude and spectrum analysis (JASA) was used to evaluate local muscle fatigue of target muscles involving in the climbing task. Results The RPE scores of T1, T2, and T3 were 11.9, 15.3, and 17.4, respectively. Subjective fatigue was found in T2 and T3 but not in T1. With the extension of climbing time, the MVE values of left and right erector spinae muscles, left and right rectus femoris, and right gastrocnemius muscle increased gradually, while the MVE values of left and right trapezius muscles and left gastrocnemius muscle increased first and then decreased. The MF values of left and right rectus femoris increased at first, then remained unchanged, while the MF values of the other muscles remained basically unchanged. In T1, three muscles, including left trapezius muscle and both side of erector spinae muscles, showed fatigue; in T2, five muscles, including both sides of erector spina muscles, right trapezius muscle, and both sides of gastrocnemius muscle appeared fatigue; in T3 , except for left rectus femoris, the other seven muscles were fatigue. Conclusion The characteristic changes of electromyography signals in the simulated climbing task are not completely consistent with the typical amplitude increase and left shift of the frequency spectrum of sEMG signals in static tasks, indicating that the application of time-domain and frequency-domain analysis methods in the evaluation of muscle fatigue in climbing tasks needs further discussion. Trapezius muscles and erector spinae muscles are the first to show fatigue in the simulation, and may be the sensitive muscle groups of muscle fatigue associated with climbing movement. Compared with subjective evaluation, surface electromyography is more sensitive in the assessment of body fatigue. Fatigue is reported about 100 s of climbing (the climbing length is about 20 m).

Objective:To investigate the expressions of MUC1, MUC4, MUC5AC and MUC16 in patients with first diagnosis of dry eye and their correlation with dry eye symptoms and signs.Methods:A cross-sectional study was conducted.Sixty-nine dry eye patients (69 eyes) as dry eye group and 40 normal volunteers (40 eyes) as normal control group were recruited in Xiamen Eye Center of Xiamen University, Beijing Tongren Hospital, West China Hospital of Sichuan University and Shanghai Puotuo District Center Hospital from December 2016 to May 2018.Symptoms were evaluated by Chinese dry eye questionnaire, Ocular Surface Disease Index (OSDI) and Dry Eye-Related Quality-of-Life Score Questionnaire (DEQS). Signs were assessed by tear film breakup time (TBUT), keratoconjunctival fluorescein sodium staining, and Schirmer I test.Conjunctival cells were collected by conjunctival impression cytology.The expression levels of MUC1, MUC4, MUC5AC and MUC16 mRNA in the two groups were determined by real-time fluorescence quantitative PCR.The correlation between the mRNA levels of conjunctival mucins and dry eye symptoms and signs were analyzed by Spearman correlation analysis.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committees of Xiamen Eye Center of Xiamen University (No.2017003), Beijing Tongren Hospital, Capital Medical University (No.TREC2016-29), West China Hospital of Sichuan University (No.2016310) and Shanghai Puotuo District Center Hospital (No.PTEC-A-2016-18-1). Written informed consent was obtained from each subject before any medical examination.Results:The expression levels of MUC1 and MUC16 mRNA in dry eye patients were 3.277(0.568, 5.790) and 1.815(1.048, 3.694), which were higher than 1.055(0.550, 2.010) and 1.024(0.541, 1.965) in normal control group (Z=819.00, P=0.008; Z=861.00, P=0.002). According to OSDI scores, MUC1 was mainly increased to 3.277(1.161, 6.226) in mild to moderate (12-32 points) dry eye patients (Z=9.04, P=0.029), and MUC16 was mainly increased to 1.968(1.074, 3.726) in severe (>32 points) dry eye patients (Z=12.24, P=0.007). MUC1 expression was positively correlated with TBUT, and was negatively correlated with corneal staining scoring and keratoconjunctival staining scoring ( r s=0.270, P=0.025; r s=-0.331, P=0.006; r s=-0.325, P=0.007). MUC16 expression was positively correlated with TBUT, and was negatively correlated with blurred vision scoring, symptom exacerbation scoring during reading, impact scoring of driving at night, impact scoring of computer and impact scoring of TV use ( r s=0.249, P=0.039; r s=-0.359, P=0.047; r s=-0.370, P=0.034; r s=-0.558, P=0.016; r s=-0.498, P=0.006; rs=-0.515, P=0.002). Conclusions:The gene expressions of MUC1 and MUC16 are higher in conjunctiva of dry eye patients.MUC1 mRNA expression is related to patients' signs.MUC16 mRNA expression is related to the quality of life of patients.