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- 저자 : Zhengxuan Li (검색결과 4 건)
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Hui Li,Mingcai Liang,Zhengxuan Wang,Yan Zhang,Qiong Wu,Lin Yang 한국식품영양과학회 2020 Journal of medicinal food Vol.23 No.6
The major aim of this study was to investigate the effect of rice protein (RP) on the activation of endogenous antioxidant defense in growing and adult rats. After 2 weeks, RP activated nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) by suppressing Kelch-like ECH-associated protein 1 (Keap1) and Cullin 3 (Cul3) in growing and adult rats. Compared with casein, the upregulation of antioxidant responsive element (ARE)-driven antioxidant expression levels (glutamate cysteine ligase catalytic subunit, glutamate cysteine ligase modulatory subunit, glutathione synthase, glutathione reductase, glutathione S-transferase, glutathione peroxidase, catalase, superoxide dismutase, heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1) were found in RP groups. Also, RP upregulated methionine sulfoxide reductase (MsrA, MsrB2, and MsrB3) expression levels in growing and adult rats. As a result, RP enhanced endogenous antioxidative capacities to reduce hepatic accumulations of malondialdehyde, protein carbonyl, and reactive oxygen species. This study demonstrates that RP exerts the endogenous antioxidant capacity in growing and adult rats, which is due to stimulating Msr antioxidant expression and activating Nrf2-ARE pathway. Results suggest that the antioxidant activity induced by RP is independent of age.
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Impact of Spring AAO on Summertime Precipitation in the North China Part: Observational Analysis
Yuan Zhengxuan,Qin Jun,Li Shuanglin,Huang Sijing,Mbululo Yassin 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.1
By using the 160 stations monthly precipitation data and NOAA-ESRL reanalysis data, the effect of spring Antarctic Oscillation (AAO) on Summer Precipitation in North China (SPNC) is studied. The analysis results show that the positive phase of March AAO leads the easterly-southerly and ascend anomalies in the southern part of North China by affecting zonal wind, and meridional circulation in the Northern Hemisphere (NH) late summer, results in more SPNC. Key regions of Antarctic sea-ice may store preceding March AAO signal which is cross-seasonal sustained by the heat exchanging with underlying surface, and the Summer Antarctic Sea-ice Index (SSI) is defined. The upward and poleward propagations of the planetary wave are enhanced in the Southern Hemisphere (SH) high latitude, and there are significant anomalous variabilities of PSI over SH low latitude, high latitude and polar regions in the high SSI years and vice versa. The wave-current interaction weakens the descending motion over the Antarctic, strengthens the circumpolar westerlies and deepens the SH polar vortex (AAO positive phase) in the high SSI years and vice versa. The results of observation and CAM5 show that SSI is positively correlated with indices of Quasi-Biennial Oscillation (QBOI). In QBO westerly phase, the SPNC anomaly in the high SSI years shows out of phase with that in the low SSI years. In the low SSI years, Rossby wave has the characteristics of anomalous southward propagation which corresponds to the abnormal weakening of ascend motion (the decrease of precipitation) over North China. Accompanied with a significant PSI anomaly, there exists a region of weak to strong wave energy over North China which is regarded as the source region of wave energy in both high and low SSI years of QBO westerly phase. But in QBO easterly phase, SPNC anomaly is not significant. QBO may be a bridge that connecting the signals of zonal wind anomalies in the stratosphere of the SH and the NH.
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L-Methionine inhibits 4-hydroxy-2-nonenal accumulation and suppresses inflammation in growing rats
Wang Zhengxuan,Liang Mingcai,Li Hui,Liu Bingxiao,Yang Lin 한국영양학회 2022 Nutrition Research and Practice Vol.16 No.6
BACKGROUND/OBJECTIVES 4-Hydroxy-2-nonenal (HNE) is a biomarker for oxidative stress to induce inflammation. Methionine is an essential sulfur-containing amino acid with antioxidative activity. On the other hand, the evidence on whether and how methionine can depress HNE-derived inflammation is lacking. In particular, the link between the regulation of the nuclear factor-κB (NF-κB) signaling pathway and methionine intake is unclear. This study examined the link between depression from HNE accumulation and the anti-inflammatory function of L-methionine in rats. MATERIALS/METHODS Male Wistar rats (3-week-old, weighing 70–80 g) were administered different levels of L-methionine orally at 215.0, 268.8, 322.5, and 430.0 mg/kg body weight for two weeks. The control group was fed commercial pellets. The hepatic HNE contents and the protein expression and mRNA levels of the inflammatory mediators were measured. The interleukin-10 (IL-10) and glutathione S-transferase (GST) levels were also estimated. RESULTS Compared to the control group, hepatic HNE levels were reduced significantly in all groups fed L-methionine, which were attributed to the stimulation of GST by L-methionine. With decreasing HNE levels, L-methionine inhibited the activation of NF-κB by up-regulating inhibitory κBα and depressing phosphoinositide 3 kinase/protein kinase B. The mRNA levels of the inflammatory mediators (cyclooxygenase-2, interleukin-1β, interleukin-6, inducible nitric oxide synthase, tumor necrotic factor alpha) were decreased significantly by L-methionine. In contrast, the protein expression of these inflammatory mediators was effectively down regulated by L-methionine. The anti-inflammatory action of L-methionine was also reflected by the up-regulation of IL-10. CONCLUSIONS This study revealed a link between the inhibition of HNE accumulation and the depression of inflammation in growing rats, which was attributed to L-methionine availability. The anti-inflammatory mechanism exerted by L-methionine was to inhibit NF-κB activation and to up-regulate GST.
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Analysis of submodule capacitor overvoltage during DC-side fault in hybrid MMC-based HVDC system
Yunbeom Gim,Zhengxuan Li,Jingwei Meng,Zexi Deng,Qiang Song 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The hybrid modular multilevel converter (MMC) consisting of half-bridge submodules (HBSMs) and full-bridge submodules (FBSMs) is one of the promising converter topologies for HVDC system, due to its fault blocking capability without applying circuit breakers and relatively lower cost compared with FBSM-MMC. However, the energy stored in the lines will cause an overvoltage in the capacitor voltages of the FBSMs. This overvoltage is significant especially when the HVDC system contains long distance transmission lines. The capacitor overvoltage can threat the safe operation of the system and the lifetime of the components, and therefore shall be appropriately regulated. This work analyzes the DC fault current blocking process of a hybrid MMC based HVDC system, determines the major factors which influence the capacitor overvoltage, and proposes corresponding mitigation measures. The simulation results of a two-terminal HVDC system on PSCAD/EMTDC with various test conditions are presented to validate the proposed analysis.
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