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Tizoxanide induces autophagy by inhibiting PI3K/Akt/ mTOR pathway in RAW264.7 macrophage cells
Jiaoqin Shou,Mi Wang,Xiaolei Cheng,Xiaoyang Wang,Lifang Zhang,Yingchun Liu,Chenzhong Fei,Chunmei Wang,Feng Gu,Feiqun Xue,Juan Li,Keyu Zhang 대한약학회 2020 Archives of Pharmacal Research Vol.43 No.2
As the main metabolite of nitazoxanide, tizoxanide(TIZ) has a broad-spectrum anti-infective effect againstparasites, bacteria, and virus. In this study, we investigatedthe effects of TIZ on autophagy by regulating the PI3K/Akt/mTOR signaling pathway. RAW264.7 macrophage cellswere treated with various TIZ concentrations. Cell viabilityassay, transmission electron microscope, and immunofluorescencestaining were used to detect the biological functionof the macrophage cells, and the expression levels of theautophagy pathway-related proteins were measured by Westernblot. Results revealed that TIZ promoted the conversionof LC3-I to LC3-II, the formation of autophagy vacuoles,and the degradation of SQSTM1/p62 in a concentration- andtime-dependent manner in RAW264.7 cells. Treatment withTIZ increased the Beclin-1 expression level and inhibitedPI3K, Akt, mTOR, and ULK1 activation. These effects wereenhanced by pretreatment with rapamycin but attenuated bypretreatment with LY294002. In addition, the conversion ofLC3-I to LC3-II was observed in Vero, 293T, and HepG2cells treated with TIZ. These data suggested that TIZ mayinduce autophagy by inhibiting the Akt/mTOR/ULK1 signalingpathway in macrophages and other cells.
Rui-cheng Feng,Yong-nian Qi,Zong-xiao Zhu,Wen-yuan Song,Hai-yan Li,Mao-mao Wang,Zhi-yuan Rui,Feng-shou Gu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.4
Molecular dynamics, an eff ective method to gain an insight into nanometric behaviour of materials, was employed to studythe nano-cutting behaviour of single crystal Ni 3 Al in nanometric scale. In this paper, comparisons were made for compressive/tensile stress, subsurface damage and surface roughness with three rake angles of a diamond tool. Subsurface damage waspartitioned by region and studied with work hardening in detail. A model for precise characterization of surface roughnesswas established with consideration of local surface fl uctuation. Simulation results showed that the chip thickness increasedas rake angle changed from negative to positive, and the boundary formed between tensile and compressive stress was inconsistent with the glide direction of stacking fault. Subsurface damage decreased as the increase of rake angle, and regularglide planes of stacking faults were found in front of the cutting tool. Further, the pinned dissociated 1/2 < 110 > superpartialdislocation with anti-phase boundary was demonstrated. The model was tested and characterized by implanted pits onperfect surface. Results showed that surface roughness can be well characterized, and an evident discrepancy was observedamong three rake angles, especially for 30° rake angle, which showed an distinct smooth surface compared with the others.
Hybrid model for the analysis of the modal properties of a ball screw vibration system
Qin Wu,Feng-shou Gu,Andrew Ball,Hua Huang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2
In accordance with the vibration characteristics of ball screw feed systems, a hybrid modeling method is proposed to study its dynamic behavior. Partially, the ball screw is modeled as a continuous body, and the remaining components are considered lumped masses, allowing for a realistic description of the dynamics of the feed system. The axial, torsional, transverse, and bending vibration models of a ball screw carriage system are established via the Rayleigh-Ritz series method based on the Timoshenko beam assumption. The established model that added the Timoshenko beam assumption obtains the coupling vibration displacement between the transverse and bending vibrations of the lead screw, which is close to real situations. Numerical simulations are conducted to investigate the changes of the natural frequency and modal shapes of ball screw systems with carriage positions. Results show that the carriage position has significant influence on the amplitude and direction of axial and transverse vibrations, substantial influence on the direction of the bending vibration, and minimal influence on the amplitude and direction of torsional vibration. These results indicate that the proposed hybrid model performs well to predict the vibration characteristics of the feed system. Moreover, the carriage position and carriage load also have a remarkable effect on the frequency response of the feed system. These results, along with the modeling approach, provide an important basis for the further study of in-machining monitoring and vibration controller design.