Comparative analysis on occupational hazards of three welding operations / 中华劳动卫生职业病杂志

Objective: To explore the occupational hazards caused by three kinds of welding operations, and to provide data support for individual protection. Methods: In October 2020, the welding fumes, metal elements and welding arc generated by three welding operations of argon gas shielded welding (JS80 welding wire) , manual welding (ZS60A welding rod) and carbon dioxide shielded welding (907A flux cored wire) were collected and measured in the welding laboratory. The samples were analyze and compare in the laboratory, and the differences of the occupational hazard factors of the three welding operations were judged. Results: The concentration of welding fume produced by carbon dioxide shielded welding, manual welding (ZS60A electrode) , and argon gas shielded welding (JS80 welding wires) were 6.80 mg/m(3), 6.17 mg/m(3), and 3.13 mg/m(3), respectively. The effective irradiance of the welding arc outside the welding mask from high to low is manual welding (ZS60A electrode) , carbon dioxide shielded welding (907A flux-cored welding wire) , and argon shielded welding (JS80 welding wire) , respectively 1 010.7, 740.9, 589.5 μW/cm(2). The long-wave ultraviolet UVA intensity generated by argon shielded welding (JS80 welding wire) is the largest, which is 1 500 μW/cm(2). The content of Mn in the three welding operations is the highest, and JS80 welding wire has the highest Mn content of 128493.2 mg/kg. 907A flux cored wire has the highest Ti content, which is 24355.5mg/kg. The electrode ZS60A has the highest Cu content, which is 24422.12 mg/kg. Conclusion: The intensity of occupational hazards is different in the three kinds of welding operations, so the methods of personal protective equipment, field exposure assessment and health monitoring should be more targeted.

Effect of tanshinone IIA on chemosensitivity of doxorubicin in breast cancer cells and its related mechanisms / 中草药

Objective To assess the effect of tanshinone IIA on the chemosensitivity of doxorubicin in breast cancer cells and investigate its related mechanisms. Methods MCF-7 and MCF-7/dox cells were respectively treated with tanshinone IIA, doxorubicin, and doxorubicin combined with tanshinone IIA. MTS assay was used to detect cell proliferation; Flow cytometry was used to analyze cell apoptosis; Scratch assay was used to evaluate cell migration; Western blotting was used to detect the expressions of APC, β-catenin, E-cadherin, MMP-2, and MMP-9. Results Tanshinone IIA could significantly enhance the inhibitory effects of doxorubicin on cell proliferation and migration of MCF-7 and MCF-7/dox cells and the effect of doxorubicin on inducing cell apoptosis. Compared to MCF-7 cells, the protein expression of APC in MCF-7/dox cells was significantly decreased (P < 0.05) while the expression of β-catenin in MCF-7/dox cells was significantly increased (P < 0.05). Compared to treatment with doxorubicin alone, combined treatment of doxorubicin and tanshinone IIA could significantly up-regulate the protein expression of APC and E-cadherin (P < 0.05) and down-regulate the protein expression of β-catenin, MMP-2, and MMP-9 (P < 0.05). Conclusion The APC/β-catenin pathway was involved in the development of doxorubicin resistance in breast cancer cells. Tanshinone IIA enhanced the chemosensitivity of doxorubicin in breast cancer cells through regulating APC/β-catenin pathway.