Aim: To study the effects of Clostridium difficile toxin A on the cytotoxity and apoptosis of human hep-atoma cell line SMMC-7721. Methods: Clone inhibiting experiment and MTT calorimetric assay were used to assay SMMC-7721 proliferation. Morphological changes relevant to the apoptosis and the DNA damage were analyzed by transmission electron microscope and single cell gel assay. The number of apoptosis cells and the expression of Bcl-2 and p53 protein were detected by the flow cytometry. Results: 0. 018- 4. 690 mg/L toxin A significantly decreased the colony information of SMMC-7721 cells, and greatly inhibited SMMC-7721 proliferation in a time- and concentration-dependent manner. Morphological changes related to apoptosis were evident under transmission electron microscope and DNA damage was detected by single cell gel assay when SMMC-7721 cultured with 4. 690 mg/L toxin A for 48 h. Toxin A 0. 0734. 690 mg/L induced apoptosis in SMMC-7721 cells from 6. 8% to 41. 8%. In addition, Toxin A 0. 293-4. 690 mg/L significant decreased Bcl-2 protein expression and increased p53 protein expression in SMMC-7721. Conclusion: These results showed that clostridium difficile toxin A had a significantly cytotoxicity in human SMMC-7721 which was attributed to toxin A induced apoptosis.

AIM: To determine whether the eukaryotic initiation factor-4E (eIF-4E) inhibition facilitates the degradation of heparanase mRNA and alters heparanase protein expression in human colon adenocarcinoma cell line, LS-174T. METHODS: A 20-mer antisense s-oligodeoxynucleotide (asODN) targeted against the translation start site of eIF-4E mRNA were introduced into LS-174T cells by lipid-mediated DNA-transfection. eIF-4E protein and mRNA levels were detected by Western blot and RT-PCR, respectively. The mRNA levels of heparanase were determined by Northern blot. The alterations of heparanase expression were confirmed by Western blot analysis. RESULTS: The 20-mer asODN against eIF-4E specifically and significantly inhibited eIF-4E protein expression. Following eIF-4E inhibition, a significant reduction of heparanase mRNA was observed on Northern blot, and at the same time, heparanase protein expression significantly decreased as well. CONCLUSIONS: The results indicate that the inhibition of eIF-4E strongly reduces the stability of heparanase mRNA in colon adenocarcinoma cell line, LS-174T and resultes in an apparent reduction in the expression of heparanase protein. [

{L-End}Objective To analyze the local muscle response under continuous ergonomic workload by simulating manual lifting, and to screen the sensitive metabolic biomarkers during fatigue process. {L-End}Methods A total of 13 healthy male volunteers were selected as the study subjects using simple random sampling method. Study subjects underwent repetitive simulated manual lifting for four periods (T1 to T4), each lasting 12 minutes. The degree of work-related fatigue in the forearm, upper arm, shoulder, back, and leg muscles, and the whole body was accessed using Borg 6-20 Rating of Perceived Exertion (RPE) Scale. The venous blood samples were collected from elbow between each two periods to detect the levels of eight metabolic biomarkers: ammonia, lactate, creatine kinase, lactate dehydrogenase (LDH), C-terminal telopeptide of type Ⅰ collagen (CTX-Ⅰ), C-terminal telopeptide of type Ⅱ collagen (CTX-Ⅱ), cartilage oligomeric matrix protein (COMP), and calcium ions. {L-End}Results The RPE scores of the study subjects for the muscles of five body parts and the whole body increased with the increasing lifting periods (all P<0.01). Fatigue was observed in all target muscles, with overall body fatigue occurring in the T2 period. The levels of ammonia, lactate, creatine kinase, LDH, COMP, and calcium ions in the serum of study subjects were higher in the T1 to T4 periods than in the T0 period (all P<0.05). The serum CTX-Ⅰ level was higher in the T1 and T3 periods than that in the T0 period (all P<0.05) , and the serum CTX-Ⅱ level was higher in the T1, T2 and T4 periods than that in the T0 period (all P<0.05). The level of these eight serum metabolic biomarkers fluctuated during the T1 to T4 periods. The serum creatine kinase level increased with the period of lifting (all P<0.05). The serum lactate level was higher in the T3 period than those in the T1 and T2 periods (all P<0.05). The serum LDH and calcium ion levels were higher in the T2 to T4 periods than that in the T1 period (all P<0.05). The serum COMP level was higher in the T2 and T3 periods than that in the T1 period (all P<0.05). Except for CTX-Ⅰ, the levels of other seven metabolic markers in serum were higher in individuals after fatigue than before fatigue (all P<0.05). {L-End}Conclusion Serum metabolic biomarkers such as ammonia, lactate, creatine kinase, calcium ions, LDH, CTX-Ⅱ, and COMP exhibit significant changes before and after fatigue. These metabolic biomarkers could be used as sensitive biomarkers for evaluating muscle fatigue during repetitive works.

Background Furniture manufacturing is one of the typical labor-intensive industries, and workers in this industry face a high risk of work-related musculoskeletal disorders (WMSDs), which seriously affect the physical and mental health of workers. Objective To explore the prevalence and potential risk factors of WMSDs among workers in a large-scale furniture manufacturing factory. Methods A cross-sectional study of 3431 workers in a furniture factory in Guangdong Province was conducted from September to December 2019. Information including reported WMSDs in various body parts in the past year, demographic characteristics, work organization factors, job characteristics, and work postures was collected by an electronic version of Musculoskeletal Disorders Questionnaire. Pearson χ² test and binary logistic regression were used to analyze the risk factors leading to WMSDs. Results The overall prevalence rate of WMSDs was 32.12% (1102/3431). The most common WMSDs symptoms occurred in the neck (16.85%), followed by the feet (15.27%), shoulders (14.81%), and hands (14.25%). The prevalence rates of WMSDs in the neck, shoulders, elbows, hands, legs, and feet were significantly different among different types of work (P<0.05). The results of multiple logistic regression analysis showed that individual factors, work organization factors, job characteristics, and awkward work postures were associated with the frequency of reporting WMSDs in specific parts of workers. Comparatively poor physical health (including moderate, poor, and very poor) was positively correlated with neck, shoulder, hand, and foot WMSDs (OR=1.479-4.077); working with an uncomfortable posture (OR=1.983) and doing the same task almost every day (OR=1.783) were positively correlated with neck pain; doing the same task almost every day (OR=2.408) and neck twisting for a long time (OR=1.830) were positively correlated with shoulder pain; bending wrists up and down frequently (OR=1.948) and bending wrists for a long time (OR=2.081) were positively correlated with hand pain; prolonged standing (OR=1.953) and often working overtime (OR=1.627) were positively correlated with feet pain; sufficient rest time was negatively correlated with WMSDs in the neck, shoulders, hands, and foot (OR=0.544-0.717). Conclusion The prevalence rate of WMSDs in furniture manufacturing workers is relatively high, and neck, feet, shoulders, and hands are the most involved body parts. The frequency of reporting WMSDs is related to individual factors, work organization factors, job characteristics, and awkward work postures.

OBJECTIVE: To analyze the relationship between the blood biochemical indexes and the local muscle fatigue of operators with local muscle fatigue caused by moderate-load repetitive manual lifting. METHODS: Five healthy male volunteers were selected as the research subjects. They repeatedly performed simulated manual lifting operation for four periods(T1-T4), 10 minutes per period. Each period was suspended for 3 minutes to be accessed for the rating of perceived exertion(RPE) score of local muscle. Meanwhile, their venous blood was collected to be detected for serum calcium ion, creatine kinase, cartilage oligomeric matrix protein(COMP), ammonia, lactic acid, lactate dehydrogenase(LDH), C-reactive protein(CRP), and collagen type Ⅱ C terminal telopeptide(CTX-Ⅱ). RESULTS: The RPE score and serum creatine kinase level of the subjects increased with the increasing of lifting time(P<0.05). Serum calcium ion levels in time periods T2, T3 and T4 were higher than that in T1(P<0.05). Serum COMP levels in T3 and T4 were higher than that in T1(P<0.05). The levels of ammonia,lactic acid, LDH, CRP and CTX-Ⅱ in each time period showed no statistical significance(P>0.05). Serum creatine kinase, calcium ion and LDH levels were positively correlated with RPE score(correlation coefficient were 0.840, 0.512, 0.741, respectively, P<0.01). CONCLUSION: Serum creatine kinase is a sensitive, effective and objective index reflecting muscle fatigue, which is suitable for evaluating the fatigue process of moderate-load repetitive activities. Serum calcium ion has a good correlation with muscle fatigue, and serum COMP can reflect muscle fatigue to some extent.

OBJECTIVE: To assess the effect of ergonomic factor load on work-related musculoskeletal disorders(WMSDs) in shipyard workers. METHODS: A total of 751 shipyard workers were selected as the research subjects using judgment sampling method. The exposure level of adverse ergonomic factors was assessed using the Quick Exposure Check method. The prevalence of WMSDs was investigated using the revised Musculoskeletal Disorders Investigating Questionnaire of our research group, and the relationship between them was analyzed. RESULTS: The proportions of high or very high level of work load exposure to the neck, back, shoulder and hand in shipyard workers from high to low were 66.4%, 63.5%, 59.8% and 43.7%(P<0.01) respectively. The proportions of occupational stress, driving, vibration and working rhythm at high or very high exposure level were 20.0%, 4.1%, 22.9% and 3.2%, respectively. The prevalence of WMSDs in four body parts of shipyard workers from high to low was the back, neck, hand and shoulder(the prevalence were 44.2%, 31.2%, 26.9% and 26.6%, respectively, P<0.01). After excluding the influence of confounding factors, multiple logistic regression analysis showed that the higher the labor load exposure level and longer of the vibration tool using, the higher the risk of shoulder WMSDs [odds ratio(OR) and 95% confidence interval(CI) were 1.25(1.04-1.51) and 1.33(1.05-1.69), respectively, P<0.05]. The higher the level of occupational stress, the higher the risk of back and neck WMSDs [OR(95%CI) was 1.29(1.05-1.58) and 1.42(1.15-1.77), respectively, P<0.05]. CONCLUSION: There was a dose-effect relationship between the exposure level of shoulder load, the time of using vibration tools and the shoulder WMSDs, and there was a dose-effect relationship between the occupational stress level and the WMSDs in the back and neck.