This study aims to investigate the effect of Chaijin Jieyu Anshen Formula on the neuroinflammation of rats with insomnia complicated with depression through the regulation of triggering receptor expressed on myeloid cells 2(TREM2)/complement protein C1q signaling pathway. Rats were randomly divided into a normal group, a model group, a positive drug group, as well as a high, medium, and low-dose groups of Chaijin Jieyu Anshen Formula, with 10 rats in each group. Except for the normal group, the other groups were injected with p-chlorophenylalanine and exposed to chronic unpredictable mild stress to establish the rat model of insomnia complicated with depression. The sucrose preference experiment, open field experiment, and water maze test were performed to evaluate the depression in rats. Enzyme-linked immunosorbent assay was employed to detect serum 5-hydroxytryptamine(5-HT), dopamine(DA), and norepinephrine(NE) levels. Hematoxylin and eosin staining and Nissl staining were used to observe the damage in nucleus accumbens neurons. Western blot and immunofluorescence were performed to detect TREM2, C1q, postsynaptic density 95(PSD-95), and synaptophysin 1(SYN1) expressions in rat nucleus accumbens, respectively. Golgi-Cox staining was utilized to observe the synaptic spine density of nucleus accumbens neurons. The results show that, compared with the model group, Chaijin Jieyu Anshen Formula can significantly increase the sucrose preference as well as the distance and number of voluntary activities, shorten the immobility time in forced swimming test and the successful incubation period of positioning navigation, and prolong the stay time of space exploration in the target quadrant test. The serum 5-HT, DA, and NE contents in the model group are significantly lower than those in the normal group, with the above contents significantly increased after the intervention of Chaijin Jieyu Anshen Formula. In addition, Chaijin Jieyu Anshen Formula can alleviate pathological damages such as swelling and loose arrangement of tissue cells in the nucleus accumbens, while increasing the Nissl body numbers. Chaijin Jieyu Anshen Formula can improve synaptic damage in the nucleus accumbens and increase the synaptic spine density. Compared to the normal group, the expression of C1q protein was significantly higher in the model group, while the expression of TREM2 protein was significantly lower. Compared to the model group, the intervention with Chaijin Jieyu Anshen Formula significantly downregulated the expression of C1q protein and significantly upregulated the expression of TREM2. Compared with the model group, the PSD-95 and SYN1 fluorescence intensity is significantly increased in the groups receiving different doses of Chaijin Jieyu Anshen Formula. In summary, Chaijin Jieyu Anshen Formula can reduce the C1q protein expression, relieve the TREM2 inhibition, and promote the synapse-related proteins PSD-95 and SNY1 expression. Chaijin Jieyu Anshen Formula improves synaptic injury of the nucleus accumbens neurons, thereby treating insomnia complicated with depression.
Animals ; Male ; Rats ; Nucleus Accumbens/metabolism* ; Drugs, Chinese Herbal/administration & dosage* ; Depression/complications* ; Membrane Glycoproteins/genetics* ; Rats, Sprague-Dawley ; Sleep Initiation and Maintenance Disorders/complications* ; Neurons/metabolism* ; Receptors, Immunologic/genetics* ; Signal Transduction/drug effects* ; Synapses/metabolism*

Objective:A retrospective analysis was conducted on the clinical characteristics and polysomnography (PSG) features of patients with obstructive sleep apnea (OSA) of different ages.Methods:From January 2015 to March 2024, the patients who underwent overnight PSG monitoring at the Sleep Respiratory Disease Diagnosis and Treatment Center, Department of Otolaryngology, Head and Neck Surgery, Sixth Medical Center of the PLA General Hospital were sequentially enrolled.A total of 4 396 patients[aged from 18 to 97(46.04±12.60)years] with OSA who met the criteria were finally enrolled and divided into the youth group (18-44 years old, n=2 099), middle-aged group (45-59 years old, n=1 641), and elderly group (≥60 years old, n=656).The differences in general condition, Epworth sleepiness Scale (ESS) score, rapid eye movement sleep (REM) sleep time in total sleep time, micro-awakening index, apnea hypopnea index (AHI), minimum oxygen saturation at night (LSpO 2), oxygen hypoxia index (ODI) and so on were compared.Multivariate Logistic regression was used to analyze the relationship between age stratification and different severity of OSA (mild 5≤AHI≤15, moderate 1530, Times per hour). Results:The neck circumference [(39.11±3.71) cm], body mass index [BMI, (26.63±3.70) kg/m2], total sleep time [(386.13±66.09) min], the percentage of deep sleep in total sleep time [(3.05±4.80)%], the percentage of REM sleep time in total sleep time [(16.73±6.83)%], apnea-hypopnea index [AHI, (31.17±19.20) events/h], oxygen desaturation index [ODI, (46.57±33.54) events/h], microarousal index [(14.82±12.27) events/h], and Epworth Sleepiness Scale (ESS) score (8.29±5.92) in the elderly group were all lower than those in the young group [neck circumference (41.36±3.37) cm, BMI (28.55±4.21) kg/m2, total sleep time [(424.67±62.21) min], the percentage of deep sleep in total sleep time (5.89±6.79)%, the percentage of REM sleep time in total sleep time (17.95±6.67)%, AHI (39.55±27.89) events/h, ODI (61.88±34.60) events/h, microarousal index (22.77±19.31) events/h, ESS score (9.63±5.82)] and the middle-aged group [neck circumference (40.75±3.59) cm, BMI (27.89±3.55)kg/m2, total sleep time [(410.98±63.02)min], the percentage of deep sleep in total sleep time (3.59±5.11)%, the percentage of REM sleep time in total sleep time (17.47±6.63)%, AHI (36.01±23.63) events/h, ODI (57.20±34.75) events/h, microarousal index (19.23±15.59) events/h, ESS score (9.98±6.11)], with F values of 102.62, 62.15, 95.87, 95.94, 8.71, 29.60, 49.72, 59.11, and 19.03, respectively, and all P values were <0.001. The proportion of females [29.57% (94/656)], the proportion of patients with hypertension [37.20% (244/656)], and the nocturnal LSpO 2 [(79.09±9.88)%] in the elderly group were all higher than those in the young group [proportion of females [6.48% (136/2 099)], proportion of patients with hypertension 18.10% (380/2 099), nocturnal LSpO 2(75.19±12.90)%] and the middle-aged group [proportion of females [15.84%(260/1 641)], proportion of patients with hypertension 33.09% (543/1 641), nocturnal LSpO 2(76.15±12.44)%], with F values of 242.62, 150.90, and 25.05, respectively, and all P values were <0.001.There were no significant differences in neck circumference, percentage of REM sleep time in total sleep time, AHI and LSpO 2 at night between young and middle-aged groups ( P>0.05). After adjusting for gender, neck circumference, BMI, and hypertension confounders, the risk of severe OSA in the older group was increased by 27.4% compared with the younger group ( OR=1.274, 95% CI=1.036-1.566, P<0.05). Further stratified analysis showed that neck circumference and BMI were independent factors for severe OSA in the young and middle-aged groups ( P<0.01), while, only neck circumference was independently associated with severe OSA in the elderly group (OR=1.119, 95% CI=1.039-1.207, P<0.01). Conclusion:The severity of OSA in young and middle-aged patients is more serious than that in elderly patients. Obesity is an important factor affecting the degree of OSA in young and middle-aged patients. After controlling for confounding factors such as obesity, the risk of severe OSA in elderly patients is higher than that in young patients, which is considered to be related to factors such as pharyngeal collapse and relaxation of pharyngeal muscles.

Objective:To explore the structural relationship between WMSDs in the upper limbs and various risk factors in the occupational population in China, based on a large sample epidemiological survey and structural equation analysis, and to establish a structural equation model, so as to lay a foundation for the prevention and control of such diseases.Methods:The Chinese version of the Musculoskeletal Disorders Electronic Questionnaire was used to conduct a nationwide survey on the prevalence of WMSDs in the upper extremity. Six factors related to WMSDs in the upper extremity were extracted by the classification standard of adverse ergonomic factors and their source and confirmatory factor analysis, including work organization, work type, upper extremity work posture, individual factors, upper extremity fatigue and upper extremity WMSDs. The structural equation analysis was carried out and the structural equation model was established.Results:The incidence of WMSDs and fatigue in the upper limbs was 24.44% and 43.76%, respectively. The adjusted structural equation model fitting indicators were generally up to the standard (GFI=1.000, AGFI=1.000, RMSEA=0.043, NFI=0.808, TLI=0.784) . The four exogenous latent variables of work organization, work type, upper limb work posture and individual factors were correlated. There was a strong positive correlation between job type and upper limb work posture ( r=0.865) , a moderate positive correlation between work organization and job type and upper limb work posture ( r=0.570, 0.490) , and a weak negative correlation between individual factors and the other three exogenous latent variables. Upper limb work posture and individual factors had direct effects on upper limb WMSDs, and the effect coefficients were 0.10 and 0.06, respectively. Upper limb fatigue played a mediating role between work organization, work type, upper limb work posture and upper limb WMSDs. The effect coefficient was 0.46, and the composition ratios of indirect effects were 100.0%, 100.0%, and 38.3%, respectively. The direct path effect of upper limb work posture, individual factors and upper limb WMSDs was weaker than the mediating path through upper limb fatigue. Conclusion:When carrying out the prevention and control of upper limbWMSDs, it is necessary to comprehensively consider the pathogenesis path of upper limb muscle fatigue and upper limb WMSDs caused by work organization, work type, and upper limb work posture, so as to provide theoretical reference for improving the prevention and control level of such diseases.

Objective:A retrospective analysis was conducted on the clinical characteristics and polysomnography (PSG) features of patients with obstructive sleep apnea (OSA) of different ages.Methods:From January 2015 to March 2024, the patients who underwent overnight PSG monitoring at the Sleep Respiratory Disease Diagnosis and Treatment Center, Department of Otolaryngology, Head and Neck Surgery, Sixth Medical Center of the PLA General Hospital were sequentially enrolled.A total of 4 396 patients[aged from 18 to 97(46.04±12.60)years] with OSA who met the criteria were finally enrolled and divided into the youth group (18-44 years old, n=2 099), middle-aged group (45-59 years old, n=1 641), and elderly group (≥60 years old, n=656).The differences in general condition, Epworth sleepiness Scale (ESS) score, rapid eye movement sleep (REM) sleep time in total sleep time, micro-awakening index, apnea hypopnea index (AHI), minimum oxygen saturation at night (LSpO 2), oxygen hypoxia index (ODI) and so on were compared.Multivariate Logistic regression was used to analyze the relationship between age stratification and different severity of OSA (mild 5≤AHI≤15, moderate 1530, Times per hour). Results:The neck circumference [(39.11±3.71) cm], body mass index [BMI, (26.63±3.70) kg/m2], total sleep time [(386.13±66.09) min], the percentage of deep sleep in total sleep time [(3.05±4.80)%], the percentage of REM sleep time in total sleep time [(16.73±6.83)%], apnea-hypopnea index [AHI, (31.17±19.20) events/h], oxygen desaturation index [ODI, (46.57±33.54) events/h], microarousal index [(14.82±12.27) events/h], and Epworth Sleepiness Scale (ESS) score (8.29±5.92) in the elderly group were all lower than those in the young group [neck circumference (41.36±3.37) cm, BMI (28.55±4.21) kg/m2, total sleep time [(424.67±62.21) min], the percentage of deep sleep in total sleep time (5.89±6.79)%, the percentage of REM sleep time in total sleep time (17.95±6.67)%, AHI (39.55±27.89) events/h, ODI (61.88±34.60) events/h, microarousal index (22.77±19.31) events/h, ESS score (9.63±5.82)] and the middle-aged group [neck circumference (40.75±3.59) cm, BMI (27.89±3.55)kg/m2, total sleep time [(410.98±63.02)min], the percentage of deep sleep in total sleep time (3.59±5.11)%, the percentage of REM sleep time in total sleep time (17.47±6.63)%, AHI (36.01±23.63) events/h, ODI (57.20±34.75) events/h, microarousal index (19.23±15.59) events/h, ESS score (9.98±6.11)], with F values of 102.62, 62.15, 95.87, 95.94, 8.71, 29.60, 49.72, 59.11, and 19.03, respectively, and all P values were <0.001. The proportion of females [29.57% (94/656)], the proportion of patients with hypertension [37.20% (244/656)], and the nocturnal LSpO 2 [(79.09±9.88)%] in the elderly group were all higher than those in the young group [proportion of females [6.48% (136/2 099)], proportion of patients with hypertension 18.10% (380/2 099), nocturnal LSpO 2(75.19±12.90)%] and the middle-aged group [proportion of females [15.84%(260/1 641)], proportion of patients with hypertension 33.09% (543/1 641), nocturnal LSpO 2(76.15±12.44)%], with F values of 242.62, 150.90, and 25.05, respectively, and all P values were <0.001.There were no significant differences in neck circumference, percentage of REM sleep time in total sleep time, AHI and LSpO 2 at night between young and middle-aged groups ( P>0.05). After adjusting for gender, neck circumference, BMI, and hypertension confounders, the risk of severe OSA in the older group was increased by 27.4% compared with the younger group ( OR=1.274, 95% CI=1.036-1.566, P<0.05). Further stratified analysis showed that neck circumference and BMI were independent factors for severe OSA in the young and middle-aged groups ( P<0.01), while, only neck circumference was independently associated with severe OSA in the elderly group (OR=1.119, 95% CI=1.039-1.207, P<0.01). Conclusion:The severity of OSA in young and middle-aged patients is more serious than that in elderly patients. Obesity is an important factor affecting the degree of OSA in young and middle-aged patients. After controlling for confounding factors such as obesity, the risk of severe OSA in elderly patients is higher than that in young patients, which is considered to be related to factors such as pharyngeal collapse and relaxation of pharyngeal muscles.

Objective:To explore the structural relationship between WMSDs in the upper limbs and various risk factors in the occupational population in China, based on a large sample epidemiological survey and structural equation analysis, and to establish a structural equation model, so as to lay a foundation for the prevention and control of such diseases.Methods:The Chinese version of the Musculoskeletal Disorders Electronic Questionnaire was used to conduct a nationwide survey on the prevalence of WMSDs in the upper extremity. Six factors related to WMSDs in the upper extremity were extracted by the classification standard of adverse ergonomic factors and their source and confirmatory factor analysis, including work organization, work type, upper extremity work posture, individual factors, upper extremity fatigue and upper extremity WMSDs. The structural equation analysis was carried out and the structural equation model was established.Results:The incidence of WMSDs and fatigue in the upper limbs was 24.44% and 43.76%, respectively. The adjusted structural equation model fitting indicators were generally up to the standard (GFI=1.000, AGFI=1.000, RMSEA=0.043, NFI=0.808, TLI=0.784) . The four exogenous latent variables of work organization, work type, upper limb work posture and individual factors were correlated. There was a strong positive correlation between job type and upper limb work posture ( r=0.865) , a moderate positive correlation between work organization and job type and upper limb work posture ( r=0.570, 0.490) , and a weak negative correlation between individual factors and the other three exogenous latent variables. Upper limb work posture and individual factors had direct effects on upper limb WMSDs, and the effect coefficients were 0.10 and 0.06, respectively. Upper limb fatigue played a mediating role between work organization, work type, upper limb work posture and upper limb WMSDs. The effect coefficient was 0.46, and the composition ratios of indirect effects were 100.0%, 100.0%, and 38.3%, respectively. The direct path effect of upper limb work posture, individual factors and upper limb WMSDs was weaker than the mediating path through upper limb fatigue. Conclusion:When carrying out the prevention and control of upper limbWMSDs, it is necessary to comprehensively consider the pathogenesis path of upper limb muscle fatigue and upper limb WMSDs caused by work organization, work type, and upper limb work posture, so as to provide theoretical reference for improving the prevention and control level of such diseases.

Objective To investigate the effects of microRNA(miR)-30a-regulated MAPK pathway on the formation of intercalation,inflammatory factors and vasoconstriction in a rat model of aortic coarctation.Methods Fifty SD rats were selected to establish the rat model of aortic coarctation,and were randomly divided into control group,model group,miR-NC group,miR-30a group and miR-30a inhibitor group,10 rats in each group.Histopathological changes in the aortic tissue and changes in the elastic fibers and collagen fibers of the aortic mesothelium were observed;The expression of miR-30a,systolic blood pressure before and after the intervention and the expression of serum inflammatory factors in each group were measured by PCR,tail artery manometry and ELISA;Matrix metalloproteinase(MMP)-6,MMP-2 protein expression and MAPK pathway were measured by Western blotting in each group.The expression of MMP-6,MMP-2 and MAPK pathway related proteins were measured by Western blotting.Results The miR-30a inhibitor group improved the degree of vessel wall tearing and disorganized internal arterial wall arrangement;The miR-30a group improved vascular remodeling;miR-30a expression was higher in the model group compared with the control group,and lower in the miR-30a group and miR-30a inhibitor group compared with the miR-NC group,P<0.05;Before the intervention,the difference in systolic blood pressure between the groups compared was not statistically significant,P>0.05;Compared with the control group,systolic blood pressure was higher in the model group,higher expression in the miR-30a group and lower expression in the miR-30a inhibitor group compared with the miR-NC group,P<0.05;compared with the control group,tumor necrosis factor(TNF)-α,interleukin(IL)-6,IL-1β expression was higher in the model group,higher expression in the miR-30a group compared with the miR-NC group,lower expression in the miR-30a inhibitor group,P<0.05;higher expression of TNF-α,MMP-6,MMP-2,Ras,Raf,P38 MAPK,ERK1/2 proteins in the model group compared with the control group,higher expression in the miR-30a group compared with the miR-NC group,lower expression in the miR-30a inhibitor group,P<0.05.Conclusion MiR-30a is involved in the process of aortic coarctation formation,inflammatory response,and regulation of aortic coarctation vascular remodeling,possibly through regulation of the MAPK signaling pathway.

Objective:To analyze the distribution characteristics of work-related musculoskeletal disorders (WMSDs) among the occupational population in China's key industries during the period from 2018 to 2023, and to provide data support for the formulation of targeted prevention strategies.Methods:Between January 1, 2018, and December 31, 2023, a cross-sectional epidemiological survey and a retrospective investigation were conducted in seven geographical regions of North China, East China, Central China, South China, Southwest China, Northwest China, and Northeast China, using a combination of epidemiological cross-sectional and retrospective surveys. The industries were stratified according to the degree of closeness to WMSDs, the size of the occupational population, and the importance of the national economy, and then cluster sampling was conducted according to the size of the enterprises (large, medium, and small) within each stratum. Representative enterprises were selected, and workers who had been employed for more than one year and met the inclusion criteria were selected as the study subjects. The survey subjects completed the Chinese version of the Musculoskeletal Disorders Survey Questionnaire online by scanning a QR code. A total of 88, 609 valid questionnaires were collected. Continuous data were described by means and standard deviations, and the standardized incidence rates of WMSDs were evaluated using chi-square tests to compare the standardized incidence rates of different body parts.Results:The standardized prevalence rate of WMSDs among the frontline working population in China was 36.7%, with the top three being the neck (21.37%), shoulders (18.23%), and lower back (14.92%). There was a statistically significant difference in the standardized prevalence rate of WMSDs between different body parts (χ 2=47577.82, P<0.05). The lowest standardized prevalence rate of WMSDs was found in the southeast coastal region of China (32.54%), while the highest was in the northwest (49.70%) and northeast regions (46.16%). The standardized prevalence rate of WMSDs decreased from 42.88% in 2018 to 29.94% in 2023. The micro-enterprise observation group had a higher concentration of WMSDs in the neck (20.66%), lower back (17.95%), and shoulders (17.79%), while the large enterprise observation group had a higher concentration in the neck (20.54%), shoulders (17.52%), and lower back (14.65%). Among the industries surveyed, the highest standardized prevalence rate of WMSDs was found in the healthcare industry (53.18%), followed by the toy manufacturing industry (50.54%), the automotive manufacturing industry (43.39%), general aviation services (42.71%), and the ship and related equipment manufacturing industry (40.56%). The standardized prevalence rate of WMSDs among women was significantly higher than that of men ( OR value=1.44, P<0.05). In addition, the standardized prevalence rate of WMSDs with multiple affected body parts (four or more body parts affected simultaneously) was higher, and the risk of WMSDs increased with subjective fatigue, showing a significant "S-shaped" trend (the OR value was 2.19, 3.16, 4.71, 5.49, and 3.97 when the RPE was 13, 15, 17, 19, and 20, respectively. χ 2trend=17.23, P<0.001) . Conclusion:The distribution characteristics of WMSDs in key industries in China show obvious differences in different parts, regions, time, enterprise scale, industry and population attributes. Agriculture, pharmaceutical manufacturing, packaging and decoration and other printing industries have a high proportion of WMSDs in multiple parts at the same time and in a single site. It is necessary to study and implement precise preventive measures according to specific regions, industries and enterprise scales, as well as the characteristics of multi-site WMSDs, so as to effectively protect the health and well-being of the working population.

Objective:To explore the occupational contact characteristics of work-related musculoskeletal disorders (WMSDs) among key occupational groups in China, assess the impact of occupational factors on the occurrence of WMSDs, and propose corresponding preventive strategies.Methods:Between January 1, 2018, and December 31, 2023, a cross-sectional epidemiological survey method was employed to retrospectively investigate the occurrence of WMSDs and related occupational factors. Valid questionnaire data from 88609 on-the-job workers in 441 enterprises across 29 industries or job types in seven regions of China were collected, and the relationship between WMSDs and various occupational factors was discussed using multifactorial logistic regression analysis. Odds ratios ( OR) and their 95% confidence intervals ( CI) were calculated to assess the impact of different factors on the risk of WMSDs occurrence, with all statistical tests performed as two-tailed tests, using P<0.05 as the criterion for statistical significance. Results:Among the surveyed subjects, 59989 were male, accounting for 67.7% (59989/88609) ; 28620 women, accounting for 32.3% (28620/88609). The standardized incidence rate of work related musculoskeletal disorders (WMSDs) in 9 parts of the body was statistically significant ( P<0.05) among different working age groups without considering specific parts. The average length of service for onset of WMSDs (regardless of location) is (4.52±2.67) years, and there is a statistically significant difference in the length of service for onset of WMSDs in different locations ( P<0.05). As the frequency of heavy object handling increases, the standardization rate and OR value of WMSDs in various parts show a significant increase trend. The incidence of WMSDs is significantly correlated with maintaining poor work posture for a long time, frequent repetitive operations, and heavy object handling ( OR=1.52, 1.45, 1.63, P<0.01) . Conclusion:This study reveals that the risk of WMSDs in China's occupational population shows a non-linear change with increasing length of service, especially with a significant increase in 10 to 25 years of service. Poor work posture, frequent repetitive operations, and heavy object handling are significantly correlated with WMSDs, providing a scientific basis for developing more accurate and effective prevention strategies for WMSDs.

Objective:To investigate the relationships and impacts between various occupational ergonomic hazards and hand and wrist fatigue, as well as work-related musculoskeletal disorders (WMSDs) of the hand and wrist, and to propose targeted preventive and intervention measures for adverse occupational ergonomic factors causing WMSDs of the hand and wrist.Methods:From 2018 to December 2023, a nationwide epidemiologic survey study of wrist WMSDs was conducted using the Chinese version of the electronic questionnaire system for musculoskeletal disorders.A total of 88, 609 valid questionnaires were collected. The exclusion criteria were as follows: patients with congenital spinal deformities, as well as those with wrist WMSDs caused by external injuries, infectious diseases, and malignant tumors. A total of 73, 497 questionnaires were finally included in the study analysis, with an effective questionnaire return rate of 82.5%. Exploratory factor analysis was used to analyze and summarize the factors affecting wrist WMSDs from the questionnaires, including individual factors, work organization, work type, wrist work posture, wrist fatigue, and wrist WMSDs as latent variables, and to hypothesize, fit, and validate the structural aspect model, as well as to conduct mediation effect analysis.Results:The incidence of WMSDs and fatigue in wrist was 12.19% and 16.30% respectively. The fitting indexes of the modified structural equation model were basically up to the standard (GFI was 0.981, AGFI was 0.973, RMSEA was 0.031, NFI was 0.863, IFI and CFI were 0.865). There is a correlation between individual factors, work organization, wrist working posture and work type. There was a low negative correlation between individual factors and other factors, and there was a positive correlation between work organization, work type and wrist WMSDs ( r=0.346, 0.295), and these two factors were positively correlated with wrist fatigue height ( r=0.862, 0.599), and were positively correlated with wrist working posture ( r=0.443, 0.620). There was moderate positive correlation between wrist working posture and wrist fatigue ( r=0.469). The three most influential factors on wrist WMSDs were work organization, individual factor and work type, and the path coefficients were 0.247, 0.210 and 0.136, respectively. The first two factors that have the greatest influence on wrist fatigue are work organization and work type, and the path coefficients are 0.758 and 0.188, respectively. Individual factors, work type, wrist working posture and work organization had direct effects on wrist WMSDs, and the effect values were 0.093, 0.253, 0.718 and 0.583, respectively. Wrist fatigue played a partial mediating role between individual factors, work type, wrist working posture and work organization and wrist WMSDs, with the indirect effect ratio of 25.6%, 45.8%, 3.2% and 65.5%. Conclusion:Wrist fatigue plays an important mediating role in the path of various factors affecting wrist WMSDs, especially in the path of work organization, work type, individual factors and wrist WMSDs. Poor wrist working posture is an important risk factor that directly affects the occurrence of wrist WMSDs.

Objective:To establish a structural equation model of lower back pain and its risk factors in occupational population in China based on a large-sample occupational epidemiological survey and structural equation analysis, so as to lay the foundation for the prevention of this disease.Methods:A total of 73497 occupational epidemiological cases were selected from June 2018 to December 2023 using the Chinese version of the Musculoskeletal Disorders Electronic Questionnaire. The results were analyzed using ergonomic hazard factors and their risk source classification criteria. Confirmatory factor analysis was then applied to extract individual factors, work organization, working postures, work types, muscle fatigue, and lower back pain. These factors were subsequently classified into six categories and structural equation model was established.Results:The main structural reliability and validity indexes of the structural equation model of lower back pain and its adverse ergonomic factors after adjustment were basically up to standard[goodness of fit index (GFI) was 0.956, the adjusted goodness of fit index (AGFI) was 0.944, the root mean square error of approximation (RMSEA) was 0.043, the normed fit index (NFI) was 0.922, the comparative fit index (CFI) was 0.923, and the Tucker-Lewis index (TLI) was 0.908], and the model fit was good. There were correlations among four exogenous latent variables: individual factors, work organization, working postures and work types. Among them, individual factors had a weak negative correlation with the three exogenous potential variables of work organization, working postures and work types ( r=-0.30, -0.11, -0.18), and work organization had a moderate positive correlation with working postures and work types ( r=0.49, 0.55). There was a strong positive correlation between work types and working postures ( r=0.72). The direct path coefficients of individual factors, working postures and muscle fatigue were 0.07, 0.11 and 0.40, respectively. The direct path coefficients of work types were -0.07. There was an indirect path mediated by muscle fatigue between work types, working postures and work organization and lower back pain, and the indirect path coefficients were: work types-muscle fatigue-lower back pain (0.15), working postures-muscle fatigue-lower back pain (-0.04) and work organization-muscle fatigue-lower back pain (0.27) . Conclusion:When carrying out the prevention and control of lower back pain, the pathogenesis of lower back pain induced by workers' muscle fatigue caused by work organization, working postures, and work types factors should be comprehensively considered, so as to provide a theoretical reference for improving the prevention and control level of lower back pain.