排序方式: 共有12条查询结果,搜索用时 171 毫秒
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Yaein Baek 《Journal of forecasting》2019,38(4):277-292
This paper constructs a forecast method that obtains long‐horizon forecasts with improved performance through modification of the direct forecast approach. Direct forecasts are more robust to model misspecification compared to iterated forecasts, which makes them preferable in long horizons. However, direct forecast estimates tend to have jagged shapes across horizons. Our forecast method aims to “smooth out” erratic estimates across horizons while maintaining the robust aspect of direct forecasts through ridge regression, which is a restricted regression on the first differences of regression coefficients. The forecasts are compared to the conventional iterated and direct forecasts in two empirical applications: real oil prices and US macroeconomic series. In both applications, our method shows improvement over direct forecasts. 相似文献
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Cancer spheres from gastric cancer patients provide an ideal model system for cancer stem cell research 总被引:1,自引:1,他引:0
Han ME Jeon TY Hwang SH Lee YS Kim HJ Shim HE Yoon S Baek SY Kim BS Kang CD Oh SO 《Cellular and molecular life sciences : CMLS》2011,68(21):3589-3605
Cancer stem cells have been hypothesized to drive the growth and metastasis of tumors. Because they need to be targeted for cancer treatment, they have been isolated from many solid cancers. However, cancer stem cells from primary human gastric cancer tissues have not been isolated as yet. For the isolation, we used two cell surface markers: the epithelial cell adhesion molecule (EpCAM) and CD44. When analyzed by flow cytometry, the EpCAM+/CD44+ population accounts for 4.5% of tumor cells. EpCAM+/CD44+ gastric cancer cells formed tumors in immunocompromised mice; however, EpCAM?/CD44?, EpCAM+/CD44? and EpCAM?/CD44+ cells failed to do so. Xenografts of EpCAM+/CD44+ gastric cancer cells maintained a differentiated phenotype and reproduced the morphological and phenotypical heterogeneity of the original gastric tumor tissues. The tumorigenic subpopulation was serially passaged for several generations without significant phenotypic alterations. Moreover, EpCAM+/CD44+, but not EpCAM?/CD44?, EpCAM+/CD44? or EpCAM?/CD44+ cells grew exponentially in vitro as cancer spheres in serum-free medium, maintaining the tumorigenicity. Interestingly, a single cancer stem cell generated a cancer sphere that contained various differentiated cells, supporting multi-potency and self-renewal of a cancer stem cell. EpCAM+/CD44+ cells had greater resistance to anti-cancer drugs than other subpopulation cells. The above in vivo and in vitro results suggest that cancer stem cells, which are enriched in the EpCAM+/CD44+ subpopulation of gastric cancer cells, provide an ideal model system for cancer stem cell research. 相似文献
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The impact of microRNAs on protein output 总被引:2,自引:0,他引:2
MicroRNAs are endogenous approximately 23-nucleotide RNAs that can pair to sites in the messenger RNAs of protein-coding genes to downregulate the expression from these messages. MicroRNAs are known to influence the evolution and stability of many mRNAs, but their global impact on protein output had not been examined. Here we use quantitative mass spectrometry to measure the response of thousands of proteins after introducing microRNAs into cultured cells and after deleting mir-223 in mouse neutrophils. The identities of the responsive proteins indicate that targeting is primarily through seed-matched sites located within favourable predicted contexts in 3' untranslated regions. Hundreds of genes were directly repressed, albeit each to a modest degree, by individual microRNAs. Although some targets were repressed without detectable changes in mRNA levels, those translationally repressed by more than a third also displayed detectable mRNA destabilization, and, for the more highly repressed targets, mRNA destabilization usually comprised the major component of repression. The impact of microRNAs on the proteome indicated that for most interactions microRNAs act as rheostats to make fine-scale adjustments to protein output. 相似文献
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Radioimmunological determination of plasma cortisol 总被引:2,自引:0,他引:2
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Park S Park SH Baek JY Jy YJ Kim KS Roth J Cho JW Choe KM 《Cellular and molecular life sciences : CMLS》2011,68(20):3377-3384
Modification of nuclear and cytosolic proteins by O-linked N-acetylglucosamine (O-GlcNAcylation) is ubiquitous in cells. The in vivo function of the protein O-GlcNAcylation, however, is not well understood. Here, we manipulated the cellular O-GlcNAcylation level in Drosophila and found that it promotes developmental growth by enhancing insulin signaling. This increase in growth is due mainly to
cell growth and not to cell proliferation. Our data suggest that the increase in the insulin signaling activity is mediated,
at least in part, through O-GlcNAcylation of Akt. These results indicate that O-GlcNAcylation is one of the crucial mechanisms involved in control of insulin signaling during Drosophila development. 相似文献
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Suresh Ramakrishna Bharathi Suresh Kwang-Hyun Baek 《Cellular and molecular life sciences : CMLS》2011,68(1):15-26
It has become apparent that ubiquitination plays a critical role in cell survival and cell death. In addition, deubiquitinating
enzymes (DUBs) have been determined to be highly important regulators of these processes. Cells can be subjected to various
stresses and respond in a variety of different ways ranging from activation of survival pathways to the promotion of cell
death, which eventually eliminates damaged cells. The regulatory mechanisms of apoptosis depend on the balanced action between
ubiquitination and deubiquitination systems. There is a growing recognition that DUBs play essential roles in regulating several
binding partners to modulate the process of apoptosis. Thus, the interplay between the timing of DUB activity and the specificity
of ubiquitin attachment and removal from its substrates during apoptosis is important to ensure cellular homeostasis. This
review discusses the role of a few ubiquitin-specific DUBs that are involved in either promoting or suppressing the process
of apoptosis. 相似文献
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P. Vecsei B. Penke R. Katzy L. Baek 《Cellular and molecular life sciences : CMLS》1972,28(9):1104-1105
Zusammenfassung Durch Immunisierung von Kaninchen mit Cortisol-21-Hemisuccinat-Rinderserumalbumin-Komplex liessen sich spezifische Antikörper mit hohem Titer gewinnen. Eine radioimmunologische Bestimmungsmethode für Plasmacortisol wird angegeben. Die Methode ist besonders bei denjenigen Fällen anzuwenden, bei denen erhöhte Konzentrationen von corticosteron oder Substanz S den protein-binding assay von Cortisol im Plasma stören. 相似文献