Abstract. Programmed cell death protein 4 (PDCD4) has recently been demonstrated to be implicated in translation and transcription, and the regulation of cell growth. However, the mechanisms underlying PDCD4 function in glioma cells remain to be elucidated. The current study investigated the function and regulation of PDCD4 and the results demonstrated that the expression of PDCD4 was significantly reduced in glioma cells compared with normal cells. When PDCD4 was overexpressed in glioma cells, the proliferation rate and invasive capability of the cells greatly decreased, suggesting that PDCD4 functions as a tumor suppressor in this cell type. In addition, the histone modification status of the PDCD4 gene was analyzed, and chromatin immunoprecipitation assay identified a high density of histone 3 lysine 27 trimethylation on the promoter of PDCD4, which was associated with the long non-coding RNA, homeobox transcript antisense RNA (HOTAIR). The expression of HOTAIR was significantly increased in glioma cells compared with normal cells, and it exerted its function in a polycomb repressive complex 2-dependent manner. These results may provide novel approaches to therapeutically target PDCD4 and HOTAIR in patients with gliomas. IntroductionHuman gliomas are the most prevalent malignant neoplasms of the central nervous system, with an annual incidence of ~5/100,000 worldwide (1). Despite the use of aggressive surgery in combination with chemotherapy, biological therapy and radiotherapy, gliomas continue to be therapeutically challenging (2). For patients with glioblastoma, the relative 5-year survival rate is <5% (3). Novel therapies for the treatment of glioma are warranted; recent advances in the understanding of the molecular and biological nature of this disease may facilitate the development of successful therapeutics (4).PDCD4 protein was initially determined to be overexpressed during apoptosis, which subsequently suppresses tumorigenesis (5,6). Loss of PDCD4 expression is closely associated with the progression of a number of tumors, including glioblastomas (7), and kidney, ovarian and lung cancer (8-10). Low PDCD4 expression levels correlate with poor outcomes in patients with glioblastoma multiforme (11). The frequent loss of PDCD4 in glioblastoma multiforme is partly due to epigenetic silencing secondary to 5' cytosine-phosphate-guanine island methylation (12), in addition to overexpression of microRNA (miRNA)-21, which targets PDCD4 mRNA for degradation (13). Although several studies have examined PDCD4 in glioma, the detailed molecular mechanisms underlying the role of PDCD4 in glioma remain poorly understood.Long non-coding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides, which are involved in various important events, including transcriptional, epigenetic and post-transcriptional regulation (14,15). A previous study profiled the lncRNA homeobox transcript antisense RNA (HOTAIR), and the results demonstrated that HOTAIR was closely correlated with poor prognosis, molecular ...
The occurrence of a partial arc can affect insulation properties of the insulator by different types of flashover. In order to investigate the influence of a partial arc on electric field distribution along the catenary insulator string, a three-dimensional model of the cap-pin insulator string with partial arc was established in this paper. The electric field distribution along the insulator string when the arc extended on the insulator surface and bridged sheds was investigated based on the electric field analysis using the finite element method. The results showed that the occurrence of a partial arc caused obvious distortion of the electric field, which was a two-dimensional axis symmetrical field before arcing to a three-dimensional field. In the case of arc extension, the sudden rise of field intensity was mostly at the rib and the shed edge, which had the local maximum field intensity. The rib and the shed edge played a certain hindrance role in the extension of the arc. The main reason for promoting the development of the arc can be attributed to thermal ionization. In the case of arc bridge sheds, the highest field intensity appeared at the edge of the last bridged shed. As the number of sheds arc-bridged increased, the maximum field intensity also increased. As the arc length increased, the electric field intensity of the arc head also increased, which resulted in an accelerated arc development. The main factor to promote the development of the arc can be attributed to electrical breakdown. The measures to hinder the rapid development of partial arcs were proposed.
To monitor the galloping state of the catenary positive feeder of the Lanzhou–Urumqi high‐speed railway in the gale area, on the basis of previous research results, an online multi‐point distributed galloping monitoring system based on wireless sensor network (WSN) was designed, and the author improves the design of each part of the catenary positive feeder galloping monitoring system to enhance its availability and reliability. By the system to collect accelerations of each galloping monitoring point, and the displacement is obtained by integrating the acceleration twice, but the integration result was seriously distorted because of the trends. A localization algorithm is proposed to correct the galloping signal waveform. Firstly, in accordance with a detailed analysis of ensemble empirical mode decomposition (EEMD) anti‐modal aliasing principle and the steps of the waveform correction method, the original signal was decomposed to obtain ten intrinsic modal functions (IMFs). Secondly, with the IMFs' characteristics as basis, a new method of trend extraction was introduced to extract and eliminate the trends in the original signal. Finally, through the analysis of the measured signal of wire galloping, the feasibility and effectiveness of the proposed method were verified by comparing its results with those of the moving average method, and the galloping trajectory of the wire is obtained by curve fitting. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.
To solve the problem of contamination flashover of a catenary insulator in an electrified railway, the collision mechanism and deposition characteristics of contamination particles on the insulator surface should be studied to ensure the safe operation of traction power supply systems. This research used horizontal and oblique cantilever insulators as objects, and established the collision model between particles and insulator surface under different arrangements. The deposition conditions of particles on the insulator surface were obtained, and the simulation model of insulator contamination accumulation was established by using the Euler two-phase flow. The difference of contamination deposition characteristics between horizontal and oblique cantilever insulators was analyzed with the volume fraction of contamination particles as the characterization parameter. By comparing the cantilever insulator with the positive feeder insulator, this study analyzed the influence of shed structure on the contamination deposition characteristics. Results show that the installation method of an insulator has an impact on the contamination deposition on the insulator surface. When particle size and wind velocity are fixed, the degree of contamination accumulation on the surface of the oblique cantilever insulator is constantly higher than that of the horizontal cantilever insulator. The insulator shed structure also has a certain effect on the contamination deposition on the insulator surface. For the cantilever insulator, the degree of contamination accumulation of the windward side is higher than that of the leeward side. However, for the positive feeder insulator, the degree of contamination accumulation of the windward side is consistently less than that of the leeward side. Measures to deal with contamination flashover of catenary insulator are proposed.
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