ObjectiveTo establish a mouse model of particulate matter 2.5 （PM_2.5）-induced dry eye and investigate whether Chufeng Yisuntang can ameliorate the PM_2.5-induced ocular surface damage by regulating the reactive oxygen species （ROS）/p38 mitogen-activated protein kinase （p38 MAPK） signaling pathway. MethodsSixty 8-week-old male C57BL/6J mice were used. Ten were randomly selected as the control group. The remaining 50 mice received topical instillation of 1 drop （0.1 mL） of 5 g·L^-1 PM_2.5 suspension in both eyes， four times daily. Successfully modeled mice were randomized into four groups （n=10）： Model， p38 MAPK inhibitor， Chufeng Yisuntang， and combination （Chufeng Yisuntang at 7.3 g·kg^-1 + p38 MAPK inhibitor SB203580 at 5 mg·kg^-1）. Chufeng Yisuntang was administered via gavage， and the inhibitor group via intraperitoneal injection. The control and model groups received equal volumes of distilled water by gavage. All treatments lasted for 4 weeks. General conditions were dynamically observed. Tear secretion， tear film break-up time， and corneal fluorescein staining were assessed. After intervention for 4 weeks， hematoxylin and eosin （HE） staining was used to examine the histopathological changes. Enzyme-linked immunosorbent assay （ELISA） was adopted to measure serum levels of ROS， malondialdehyde （MDA）， superoxide dismutase （SOD） 1， and SOD2. Western blot and Real-time PCR were employed to determine the protein and gene levels， respectively， of p38 MAPK， B-cell lymphoma-2 （Bcl-2）， Bcl-2-associated X protein （Bax）， and cysteinyl aspartate-specific proteinase-3 （Caspase-3） in the corneal tissue. ResultsCompared with the control group， the model group exhibited reduced tear secretion volume and tear film breakup time， along with increased corneal fluorescein staining scores （P<0.01）. Compared with the model group， the Chufeng Yisuntang group， p38 MAPK inhibitor group， and combination group demonstrated increased tear secretion volume and tear film breakup time， along with decreased corneal fluorescein staining scores （P<0.01）. HE staining revealed that compared with the control group， the model group exhibited marked increases in corneal epithelial cell layers and epithelial thickness， along with reduced meibomian gland acini and intensely stained， densely packed nuclei around the acini. Compared with the model group， the Chufeng Yisuntang group， p38 MAPK inhibitor group， and combination group showed intact corneal structure， improved cell morphology， and reduced damage severity. ELISA revealed elevated ROS and MDA levels （P<0.01） and decreased SOD1 and SOD2 levels （P<0.01） in the model group compared with the control group. Compared with the model group， Chufeng Yisuntang， p38 MAPK inhibitor， and the combination lowered ROS and MDA levels （P<0.01）， while raising SOD1 and SOD2 levels （P<0.05， P<0.01）. Western blot revealed that compared with the control group， the model group exhibited increased protein levels of p38 MAPK， Bax， and Caspase-3 （P<0.01） and reduced protein level of Bcl-2 （P<0.01）. Compared with the model group， Chufeng Yisuntang， p38 MAPK inhibitor， and the combination down-regulated the protein levels of p38 MAPK， Bax， and Caspase-3 （P<0.01）， while up-regulating the protein level of Bcl-2 （P<0.01）. Compared with the Chufeng Yisuntang group， the combination group exhibited decreased protein levels of p38 MAPK， Bax， and Caspase-3 （P<0.01） and increased protein level of Bcl-2 （P<0.01）. Real-time PCR revealed that compared with the control group， the model group exhibited upregulated mRNA levels of p38 MAPK， Bax， and Caspase-3 （P<0.01）， and downregulated mRNA level of Bcl-2 （P<0.01）. Compared with the model group， Chufeng Yisuntang， p38 MAPK inhibitor， and the combination down-regulated the mRNA levels of p38 MAPK， Bax， and Caspase-3 （P<0.01）， while up-regulating the mRNA level of Bcl-2 （P<0.05， P<0.01）. Compared with the Chufeng Yisuntang group， the combination group exhibited decreased mRNA levels of p38 MAPK， Bax， and Caspase-3 expression （P<0.05， P<0.01） and increased mRNA level of Bcl-2 （P<0.01）. ConclusionChufeng Yisuntang may partially protect against PM_2.5-induced corneal injury by inhibiting the ROS/p38 MAPK pathway， enhancing antioxidant defense， and reducing epithelial apoptosis.

ObjectiveThis paper aims to investigate the effects and mechanism of Mimenghua prescription in modulating the mitogen-activated protein kinase kinase （MEK）/rat sarcoma viral oncogene homolog （Ras）/rapidly accelerated fibrosarcoma kinase （Raf）/extracellular signal-regulated kinase （ERK） signaling pathway to inhibit inflammatory responses in a dry eye animal model. MethodsA total of 60 C57BL/6J mice （eight weeks old， half male and half female） were used in the experiment. Ten mice were randomly selected as the blank control group， while the remaining 50 were exposed to a controlled dry system and received instillation of 0.2% benzalkonium chloride （BAC） into the eyes for four weeks to establish a dry eye mouse model. After successful modeling， the mice were randomly divided into five groups： Model group， sodium hyaluronate group， and Mimenghua prescription groups with low dose （4.83 g·kg^-1）， medium dose （9.67 g·kg^-1）， and high dose （19.34 g·kg^-1）. The mice in the model group received an equal volume of normal saline via gavage for four weeks. The mice in the sodium hyaluronate group received instillation of sodium hyaluronate eye drops twice daily for 14 consecutive days. The tear secretion volume， tear film break-up time （TBUT）， and corneal fluorescein staining were evaluated once every two weeks. After four weeks of administration， mice were euthanized， and their lacrimal gland tissues and corneas were harvested. Hematoxylin-eosin （HE） staining was used to assess histopathological morphology. Western blot was performed to detect the protein expression levels of MEK， Ras， Raf， and ERK. Enzyme-linked immunosorbent assay （ELISA） was used to measure the contents and expressions of MEK， Ras， Raf， ERK， and interleukin （IL）-1β in lacrimal gland and corneal tissues of the mice in each group. Quantitative real-time polymerase chain reaction （Real-time PCR） was employed to determine mRNA expression levels of MEK， Ras， Raf， and ERK. ResultsThe Mimenghua prescription groups and the sodium hyaluronate group exhibited significantly increased tear secretion volume （P<0.05） and prolonged TBUT （P<0.05） after treatment. Ocular surface damage of mice was visibly recovered. Western blot results indicated that protein expression levels of MEK， Ras， Raf， and ERK in the lacrimal gland and corneal tissues were significantly downregulated in the sodium hyaluronate group and Mimenghua prescription group with high dose （P<0.05）. ELISA results showed that IL-1β levels were highest in the model group but significantly reduced in the sodium hyaluronate group and Mimenghua prescription groups （P<0.05）. Both ELISA and Real-time PCR results demonstrated that the expression levels of MEK， Ras， Raf， and ERK in the lacrimal glands and corneal tissues were significantly elevated in the model group （P<0.05）， but markedly downregulated in the sodium hyaluronate group and Mimenghua prescription groups （P<0.05）， suggesting that Mimenghua prescription can decrease the expressions of MEK， Ras， Raf， and ERK in the lacrimal glands and corneal tissues. ConclusionMimenghua prescription can reduce inflammatory responses， increase tear secretion， prolong TBUT， and promote corneal recovery by inhibiting the MEK， Ras， Raf， and ERK signaling pathways in lacrimal gland and corneal tissues.

ObjectiveThis paper aims to investigate the effect and mechanism of Runmu Xiaoyao powder on mice with dry eye and the syndrome of liver depression-heat syndrome based on the toll-like receptor 4 （TLR4）/myeloid differentiation primary response protein 88 （MyD88）/nuclear factor-κB （NF-κB） signaling pathway. MethodsSixty-six C57BL/6J female mice were randomly divided into a normal group， a model group， a sodium hyaluronate group， and high-， medium-， and low-dose Runmu Xiaoyao powder groups， with 11 mice per group. Except for those in the normal group， mice in the other groups were subjected to mouse models with dry eye and liver depression-heat syndrome by instilling a benzalkonium chloride solution and applying chronic pain stimulation in a dry environment. After modeling， mice in the high-， medium-， and low-dose Runmu Xiaoyao powder groups were administered intragastrically with 29.7， 14.85， 7.43 g·kg^-1， respectively， twice a day for 14 consecutive days. The mice in the sodium hyaluronate group received 5 μL of sodium hyaluronate eye drops in each eye twice daily. The mice in the normal and model groups were administered intragastrically with an equal volume of deionized water. Measurements were taken of tear secretion in mice， irritability scores， corneal fluorescein staining， and histopathological changes in the cornea， lacrimal glands， meibomian glands， and liver tissue. Enzyme-linked immunosorbent assay （ELISA） was used to detect the levels of interleukin-1β （IL-1β） and tumour necrosis factor-α （TNF-α） in serum. Immunohistochemistry （IHC） was used to detect the protein expression of IL-1β and TNF-α in corneal and lacrimal gland tissues. Real-time quantitative polymerase chain reaction（Real-time PCR） and Western blot were employed to detect the mRNA and protein expressions of TLR4， MyD88， and NF-κB p65 in corneal， lacrimal gland， and meibomian gland tissues. ResultsCompared with those in the normal group， mice in the model group exhibited significantly reduced tear secretion， significantly higher irritability scores， and more pronounced corneal fluorescence staining， with marked pathological damage observed in the cornea， lacrimal glands， meibomian glands， and liver tissue. IL-1β and TNF-α levels in serum were significantly elevated. The protein expressions of IL-1β and TNF-α in corneal and lacrimal gland tissues， as well as the mRNA and protein expressions of TLR4， MyD88， and NF-κB p65 in corneal， lacrimal gland， and meibomian gland tissues， were all significantly increased （P<0.01）. Compared with the model group， the sodium hyaluronate group and Runmu Xiaoyao powder groups with different doses exhibited increased tear secretion to varying degrees， alleviated corneal fluorescence staining and histopathological damage， reduced IL-1β and TNF-α levels in serum， and downregulated protein expressions of IL-1β and TNF-α in corneal and lacrimal gland tissues， as well as the mRNA and protein expressions of TLR4， MyD88， and NF-κB p65 in corneal， lacrimal gland， and meibomian gland tissues. The high-dose Runmu Xiaoyao powder group demonstrated a more pronounced effect， with multiple indicators showing superior results compared to those in the sodium hyaluronate group （P<0.05， P<0.01）. ConclusionRunmu Xiaoyao powder down-regulates the TLR4/MyD88/NF-κB signaling pathway activity in the cornea， lacrimal glands， and meibomian glands of model mice with dry eye and liver depression-heat syndrome， thereby suppressing inflammatory responses and mitigating ocular surface tissue damage. The therapeutic effect is dose-dependent， and the high-dose group exerts the most prominent effect.

Objective: To investigate the protective effects of Gouqizi (Lycii Fructus, GQZ)-Danshen (Salviae Miltiorrhizae Radix et Rhizoma, DS) against hydrogen peroxide (H2O2)-induced oxidative injury in 661W retinal photoreceptor cells and to explore whether these effects involve angiopoietin-like 4 (ANGPTL4). Methods: Liquid chromatography-mass spectrometry (LC-MS) was used to identify the major components of GQZ-DS aqueous extract. An H2O2-induced oxidative injury model was established in 661W cells. Working concentrations of H2O2 and GQZ-DS were determined using the cell counting kit-8 (CCK-8) assay. Cells were subjected to GQZ-DS, ANGPTL4 knockdown, or ANGPTL4 overexpression as indicated. Flow cytometry was used to analyze cell cycle distribution, apoptotic rate, and intracellular reactive oxygen species (ROS). Colorimetric determination of malondialdehyde (MDA) content and superoxide dismutase (SOD) activity using the thiobarbituric acid (TBA) method was performed. The protein expression level of ANGPTL4 was assessed by immunofluorescence. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to quantify the mRNA level of ANGPTL4. Western blot was used to detect the protein levels of ANGPTL4 and cleaved caspase-3. Results: LC-MS identified five major constituents in the GQZ-DS aqueous extract: 2-O-β-D-glucopyranosyl-L-ascorbic acid, rutin, D-galactose, salvianolic acid A, and tanshinone IIA. The CCK-8 method selected 300 μmol/L H2O2 as the oxidative stress condition for experiments, and 0.05 and 0.1 g/mL were selected as the low and high doses of GQZ-DS, respectively, for subsequent experiments. The intervention with H2O2 resulted in reduced cell viability, elevated ROS and MDA levels, decreased SOD activity, increased apoptotic rate, upregulated cleaved caspase-3 expression, and G0/G1 phase cell cycle arrest of 661W cells. Both low and high doses of GQZ-DS alleviated these alterations, with high dose exhibiting stronger protective effects (P < 0.05 or P < 0.01). GQZ-DS also downregulated ANGPTL4 expression at both the mRNA and protein levels. Following plasmid transfection of cells, the study further revealed that ANGPTL4 knockdown mitigated oxidative stress and apoptosis-related injury, whereas ANGPTL4 overexpression exacerbated these pathological changes. Moreover, GQZ-DS partially reversed the degree of cellular oxidative damage induced by ANGPTL4 overexpression. Conclusion GQZ-DS can alleviate the H2O2-induced oxidative injury of 661W retinal photoreceptor cells, and the effects are related to the down-regulation of ANGPTL4 expression.

ObjectiveTo investigate the mechanism of ferroptosis mediated by long-chain acyl-CoA synthetase 4 （ACSL4） signalling pathway in rats with coronary heart disease with blood stasis syndrome and the intervention effect of Xuefu Zhuyutang. MethodsSPF male SD rats were randomly divided into normal group， sham-operation group， model group， trimetazidine group （5.4 mg·kg^-1）， low-， medium-， and high-dose group （3.51， 7.02，14.04 g·kg^-1） of Xuefu Zhuyutang. The coronary artery left anterior descending ligation method was used to prepare a model of coronary heart disease with blood stasis syndrome， and continuous treatment for 7 d was conducted， while the sham-operation group was only threaded and not ligated. The general macroscopic symptoms of the rats were observed， and indicators such as electrocardiogram， echocardiography， and blood rheology were detected. The pathological morphology of myocardial tissue was observed by hematoxylin-eosin （HE） staining， and the changes in mitochondria in myocardial tissue were observed by transmission electron microscopy. The level of iron deposition in myocardial tissue was observed by Prussian blue staining. The levels of 12-hydroxyeicosatetraenoic acid （12-HETE） and 15-HETE were detected in serum by enzyme-linked immunosorbent assay. A biochemical colourimetric assay was used to detect the levels of Fe²⁺， lipid peroxidation （LPO）， glutathione （GSH）， and T-GSH/glutathione disulfide （GSSG） in myocardial tissue. DCFH-DA fluorescence quantitative assay was employed to detect the levels of reactive oxygen species （ROS）. Western blot and Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was adopted to detect the protein and mRNA expressions of glutathione peroxidase 4 （GPX4）， ferritin heavy chain 1 （FTH1）， ACSL4， and ly-sophosphatidylcholine acyltransferase3 （LPCAT3） in myocardial tissue. ResultsCompared with those in the normal group， the rats in the model group were poor in general macroscopic symptoms. The electrocardiogram showed widened QRS wave amplitude and increased voltage， bow-back elevation of the ST segments， elevated T waves， J-point elevation， and accelerated heart rate. Echocardiography showed a significant reduction in left ventricular ejection fraction （LVEF） and left ventricular fraction shortening （LVFS） （P<0.01）. Blood rheology showed that the viscosity of the whole blood （low， medium， and high rate of shear） was significantly increased （P<0.01）. HE staining showed an abnormal structure of myocardial tissue. There was a large area of myocardial necrosis and inflammatory cell infiltration and a large number of connective tissue between myocardial fibers. Transmission electron microscopy showed that the mitochondria were severely atrophy or swelling. The cristae were reduced or even broken， and the matrix was flocculent or even vacuolated. Prussian blue staining showed that there were a large number of iron-containing particles， and the iron deposition was obvious. The content of 12-HETE and 15-HETE in the serum was significantly increased （P<0.01）. The content of Fe²⁺， LPO， and ROS in myocardial tissue was significantly increased （P<0.01）. The content of GSH was significantly decreased （P<0.01）， and T-GSH/GSSG was decreased （P<0.01）. The protein and mRNA expressions of GPX4 and FTH1 in myocardial tissue were both significantly decreased （P<0.05， P<0.01）， while those of ACSL4 and LPCAT3 increased significantly （P<0.01）. Compared with the model group， the general macroscopic symptoms and electrocardiogram results of rats in low-， medium- and high-dose groups of Xuefu Zhuyutang were alleviated， and the differences in LVEF/LVFS ratios were all significantly increased （P<0.05， P<0.01）. The differences in whole-blood viscosity （low， medium， and high rate of shear） were all significantly decreased （P<0.01）. The results of HE staining and transmission electron microscopy showed that the morphology， structure， and mitochondria of cardiomyocytes were improved. The content of 12-HETE and 15-HETE in serum was reduced to different degrees in low-， medium-， and high-dose groups of Xuefu Zhuyutang （P<0.05， P<0.01）. The content of Fe²⁺， LPO， and ROS was significantly reduced in the medium- and high-dose groups of Xuefu Zhuyutang （P<0.05， P<0.01）， and the content of GSH and T-GSH/GSSG was significantly increased （P<0.05， P<0.01）. The protein and mRNA expressions of GPX4 and FTH1 were significantly increased to varying degrees in the medium- and high-dose groups of Xuefu Zhuyutang （P<0.05， P<0.01）， and ACSL4 and LPCAT3 were decreased to different degrees in the low-， medium-， and high-dose groups of Xuefu Zhuyutang （P<0.05， P<0.01）. ConclusionXuefu Zhuyutang can regulate iron metabolism and anti-lipid oxidation reaction to mediate ferroptosis through the ACSL4 signalling pathway， thus exerting a protective effect on rats with coronary heart disease with blood stasis syndrome.

Objective To analyze the elevated blood pressure status and its influencing factors among manufacturing workers in Foshan City. Methods A total of 565 795 manufacturing workers who underwent occupational medical examinations in Foshan City from 2017 to 2023 were included. Data of workers were obtained from the Guangdong Provincial Key Occupational Disease Monitoring and Management Platform. The influencing factors of elevated blood pressure were analyzed using descriptive epidemiological methods. Results A total of 89 526 cases of elevated blood pressure were detected among the 565 795 workers, with a detection rate of 15.82%. From 2017 to 2023, the annual detection rate of elevated blood pressure was 14.11%, 15.00%, 14.69%, 15.94%, 17.00%, 16.90%, and 16.68%, respectively, showing an overall upward trend (P<0.01). The top three industries with the highest detection rates of elevated blood pressure were instrument and meter manufacturing; wood processing and the manufacture of wood, bamboo, rattan, palm, and straw products; as well as agricultural and sideline food processing. Binary logistic regression analysis showed that male workers had a higher risk of elevated blood pressure than female workers (P<0.01). The risk of elevated blood pressure in workers increased with age, years of occupational hazard exposure, and duration of dust exposure (all P<0.05). Workers exposed to noise for more than three years had a higher risk of elevated blood pressure than those without noise exposure (P<0.05). The risk of elevated blood pressure among workers in Nanhai, Shunde, and Gaoming districts was higher than that in Chancheng District (all P<0.01). Workers originating from Northeast and Northwest China had a higher risk of elevated blood pressure than those from North China (all P<0.05). Workers from smaller-scale enterprises had higher risk of elevated blood pressure (all P<0.01). Conclusion Targeted blood pressure health interventions in Foshan City should be strengthened for male manufacturing workers who are older, have longer working years, and originate from Northeast and Northwest China. The development of exemplary health enterprises should be promoted, particularly among micro- and small-sized enterprises and key industries. Enhanced occupational health management is especially needed for positions with high intensity noise exposure and high concentration dust exposure.

Objective To analyze the influencing factors of postoperative hypoxemia after whole lung lavage (WLL) in patients with pneumoconiosis and to evaluate the predictive value of lung ultrasound scores. Methods A total of 757 patients with pneumoconiosis who underwent unilateral large-volume WLL were selected as the research subjects by continuous sampling method. The patients with hypoxemia after large-volume WLL were assigned to the observation group (82 cases), and those without hypoxemia were assigned to the control group (675 cases). Patients′ basic information and clinical data of the two groups were collected using a retrospective investigation method. The binary logistic regression analysis was used to analyze the influencing factors of hypoxemia after large-volume WLL in patients with pneumoconiosis, and receiver operating characteristic (ROC) curve analysis was conducted to assess the predictive value of ultrasound indicators. Results The combined rate of postoperative hypoxemia in the patients was 10.8% (82/757). The multivariate logistic regression analysis showed that the risk of hypoxemia in patients aged ≥65 years was higher than that in patients aged <65 years (P<0.05). The risk of hypoxemia was higher in patients with increased pre-extubation lung ultrasound score than those with lower pre-extubation lung ultrasound score (P<0.01). Patients with a higher partial pressure of carbon dioxide in arterial blood (PaCO₂) had a higher risk of concurrent hypoxemia than those with a lower pressure (P<0.01), while patients with lower arterial partial pressure of oxygen (PaO₂) had a higher risk of concurrent hypoxemia than those with higher PaO₂ (P<0.01). Pearson correlation analysis showed that lung ultrasound scores were negatively correlated with PaO₂ and positively correlated with PaCO₂ (both P<0.01). The ROC curve analysis showed that the area under the curve was 0.855, the 95% confidence interval was 0.828 to 0.879, the diagnostic sensitivity was 84.2%, and the specificity was 75.1%. Conclusion Age, pre-extubation lung ultrasound score, and PaCO₂ are risk factors for hypoxemia after WLL in patients with pneumoconiosis, while PaO₂ is a protective factor. Pre-extubation lung ultrasound scoring demonstrates good accuracy in predicting postoperative hypoxemia among pneumoconiosis patients after WLL.

The theory of "turbid pathogen harming the clarity" was proposed by YE Tianshi in his book Wenre Lun, which can be applied to clear orifices diseases such as ear, eye, nose, and mouth. Based on the location and characteristics of vitreous opacity, as well as its understanding by medical professionals throughout history, this article points out that the core pathogenesis of vitreous opacity is "turbid pathogen harming the clarity" and the obstruction of the spirit light, and the basic pathogenesis is: unfavorable liver and gallbladder conditions, damp heat accumulation and turbidity; imbalance of middle jiao, qi deficiency leading to turbidity; kidney failure with yang deficiency, stagnant water and fluids; and stagnation entering the collaterals for an extended time, causing blockage and turbidity. And based on the pathogenesis of "turbid pathogen harming the clarity" , corresponding treatment principles are proposed: soothing liver and promoting bile flow, clearing heat and eliminating turbidity; cultivating soil to produce gold, enhancing clarity and reducing turbidity; tonifying kidney and promoting yang, warming and dispelling turbid pathogens; and removing blood stasis and activating collaterals, dispelling turbidity and unblocking the orifices. Based on the theory of "turbid pathogen harming the clarity" , this article summarizes the pathogenesis and treatment of vitreous opacity, in order to provide new ideas for traditional Chinese medicine treatment of this disease.

Objective To investigate the clinical efficacy of recombinant human granulocyte-macrophage colony-stimulating factor(rhGM-CSF)combined with bifidobacterium in the treatment of oral mucositis after chemotherapy.Methods A total of 60 post-chemotherapy patients with oral mucositis admitted to Ganzhou Cancer Hospital of Jiangxi Province from January 2023 to December 2024 were selected as subjects,the patients were divided into observation group(n=30)and control group(n=30)by using a randomized digital table method.The control group received rhGM-CSF mouthwash treatment,while the observation group was additionally administered bifidobacterium-lactobacillus triple live capsules orally.Clinical efficacy,symptom scores,inflammatory factor levels,oral microbiota indicators,and treatment safety were evaluated after 2 weeks of treatment.Results After treatment,the total effective rate in observation group was significantly higher than that in control group(P＜0.05).Post-treatment evaluations showed that patients in observation group exhibited lower scores for edema,congestion,and ulceration,along with reduced pain visual analog scores and decreased levels of inflammatory markers including Toll-like receptor 4,lectin-3,and interleukin-8,the difference were statistically significant(P＜0.05).After treatment,the oral microecological flora of patients in observation group,including lactic acid bacteria and bifidobacterium,were higher than that of control group,while porphyromonas gingivalis and fusetella were lower than that of control group,the difference were statistically significant(P＜0.05).Conclusion The clinical effect of rhGM-CSF combined with bifidobacterium in the treatment of oral mucositis after chemotherapy was significant,which could reduce various symptoms of patients,inhibit inflammatory factors,improve oral microecology,and have good safety.

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.