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431.
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
432.
In this paper we compare the in‐sample fit and out‐of‐sample forecasting performance of no‐arbitrage quadratic, essentially affine and dynamic Nelson–Siegel term structure models. In total, 11 model variants are evaluated, comprising five quadratic, four affine and two Nelson–Siegel models. Recursive re‐estimation and out‐of‐sample 1‐, 6‐ and 12‐month‐ahead forecasts are generated and evaluated using monthly US data for yields observed at maturities of 1, 6, 12, 24, 60 and 120 months. Our results indicate that quadratic models provide the best in‐sample fit, while the best out‐of‐sample performance is generated by three‐factor affine models and the dynamic Nelson–Siegel model variants. Statistical tests fail to identify one single best forecasting model class. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
433.
Bootstrap Replacement to Validate the Influence of the Economic Cycle on the Structure and the Accuracy Level of Business Failure Prediction Models
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Montserrat Manzaneque Domingo GarcíA‐Pérez‐De‐Lema Marcos Antón Renart 《Journal of forecasting》2015,34(4):275-289
The aim of this study was to answer the question of how the economic cycle affects the stability and efficiency of business failure prediction models, using bootstrap replacement method for validation. We analyse 2228 Spanish small and medium‐sized enterprises for the period 2001–2009, and divide it into three different phases of the economic cycle (growth, crisis, recession). We find that the structure and the ability of business failure prediction models are different according to the economic cycle. These findings are relevant for the debate on the most suitable financial ratios when developing business failure prediction models and to pose their accuracy level in these prediction models. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
434.
Monetary Aggregates to Improve Early Output Gap Estimates in the Euro Area: An Empirical Assessment
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Jens Boysen‐Hogrefe 《Journal of forecasting》2015,34(7):533-542
Output gap estimates at the current edge are subject to severe revisions. This study analyzes whether monetary aggregates can be used to improve the reliability of early output gap estimates as proposed by several theoretical models. A real‐time experiment shows that real M1 can improve output gap estimates for euro area data. For many periods the cyclical component of real M1 shows good results, while a forecasting strategy based on projecting GDP series seems to be more robust and provides superior results during the Great Recession. Broader monetary aggregates provide no superior information for output gap estimates. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
435.
Michael McAleer Juan‐Ángel Jiménez‐Martín Teodosio Pérez‐Amaral 《Journal of forecasting》2013,32(3):267-288
A risk management strategy designed to be robust to the global financial crisis (GFC), in the sense of selecting a value‐at‐risk (VaR) forecast that combines the forecasts of different VaR models, was proposed by McAleer and coworkers in 2010. The robust forecast is based on the median of the point VaR forecasts of a set of conditional volatility models. Such a risk management strategy is robust to the GFC in the sense that, while maintaining the same risk management strategy before, during and after a financial crisis, it will lead to comparatively low daily capital charges and violation penalties for the entire period. This paper presents evidence to support the claim that the median point forecast of VaR is generally GFC robust. We investigate the performance of a variety of single and combined VaR forecasts in terms of daily capital requirements and violation penalties under the Basel II Accord, as well as other criteria. In the empirical analysis we choose several major indexes, namely French CAC, German DAX, US Dow Jones, UK FTSE100, Hong Kong Hang Seng, Spanish Ibex 35, Japanese Nikkei, Swiss SMI and US S&P 500. The GARCH, EGARCH, GJR and RiskMetrics models as well as several other strategies, are used in the comparison. Backtesting is performed on each of these indexes using the Basel II Accord regulations for 2008–10 to examine the performance of the median strategy in terms of the number of violations and daily capital charges, among other criteria. The median is shown to be a profitable and safe strategy for risk management, both in calm and turbulent periods, as it provides a reasonable number of violations and daily capital charges. The median also performs well when both total losses and the asymmetric linear tick loss function are considered Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
436.
Valerie Le Fourn Sujin Park Insook Jang Katarina Gaplovska-Kysela Bruno Guhl Yangsin Lee Jin Won Cho Christian Zuber Jürgen Roth 《Cellular and molecular life sciences : CMLS》2013,70(11):1985-2002
Multisubunit protein complexes are assembled in the endoplasmic reticulum (ER). Existing pools of single subunits and assembly intermediates ensure the efficient and rapid formation of complete complexes. While being kinetically beneficial, surplus components must be eliminated to prevent potentially harmful accumulation in the ER. Surplus single chains are cleared by the ubiquitin–proteasome system. However, the fate of not secreted assembly intermediates of multisubunit proteins remains elusive. Here we show by high-resolution double-label confocal immunofluorescence and immunogold electron microscopy that naturally occurring surplus fibrinogen Aα–γ assembly intermediates in HepG2 cells are dislocated together with EDEM1 from the ER to the cytoplasm in ER-derived vesicles not corresponding to COPII-coated vesicles originating from the transitional ER. This route corresponds to the novel ER exit path we have previously identified for EDEM1 (Zuber et al. Proc Natl Acad Sci USA 104:4407–4412, 2007). In the cytoplasm, detergent-insoluble aggregates of fibrinogen Aα–γ dimers develop that are targeted by the selective autophagy cargo receptors p62/SQSTM1 and NBR1. These aggregates are degraded by selective autophagy as directly demonstrated by high-resolution microscopy as well as biochemical analysis and inhibition of autophagy by siRNA and kinase inhibitors. Our findings demonstrate that different pathways exist in parallel for ER-to-cytoplasm dislocation and subsequent proteolytic degradation of large luminal protein complexes and of surplus luminal single-chain proteins. This implies that ER-associated protein degradation (ERAD) has a broader function in ER proteostasis and is not limited to the elimination of misfolded glycoproteins. 相似文献
437.
Dibbens LM Tarpey PS Hynes K Bayly MA Scheffer IE Smith R Bomar J Sutton E Vandeleur L Shoubridge C Edkins S Turner SJ Stevens C O'Meara S Tofts C Barthorpe S Buck G Cole J Halliday K Jones D Lee R Madison M Mironenko T Varian J West S Widaa S Wray P Teague J Dicks E Butler A Menzies A Jenkinson A Shepherd R Gusella JF Afawi Z Mazarib A Neufeld MY Kivity S Lev D Lerman-Sagie T Korczyn AD Derry CP Sutherland GR Friend K Shaw M Corbett M Kim HG Geschwind DH Thomas P Haan E Ryan S McKee S 《Nature genetics》2008,40(6):776-781
Epilepsy and mental retardation limited to females (EFMR) is a disorder with an X-linked mode of inheritance and an unusual expression pattern. Disorders arising from mutations on the X chromosome are typically characterized by affected males and unaffected carrier females. In contrast, EFMR spares transmitting males and affects only carrier females. Aided by systematic resequencing of 737 X chromosome genes, we identified different protocadherin 19 (PCDH19) gene mutations in seven families with EFMR. Five mutations resulted in the introduction of a premature termination codon. Study of two of these demonstrated nonsense-mediated decay of PCDH19 mRNA. The two missense mutations were predicted to affect adhesiveness of PCDH19 through impaired calcium binding. PCDH19 is expressed in developing brains of human and mouse and is the first member of the cadherin superfamily to be directly implicated in epilepsy or mental retardation. 相似文献
438.
Raychaudhuri S Remmers EF Lee AT Hackett R Guiducci C Burtt NP Gianniny L Korman BD Padyukov L Kurreeman FA Chang M Catanese JJ Ding B Wong S van der Helm-van Mil AH Neale BM Coblyn J Cui J Tak PP Wolbink GJ Crusius JB van der Horst-Bruinsma IE Criswell LA Amos CI Seldin MF Kastner DL Ardlie KG Alfredsson L Costenbader KH Altshuler D Huizinga TW Shadick NA Weinblatt ME de Vries N Worthington J Seielstad M Toes RE Karlson EW Begovich AB Klareskog L Gregersen PK Daly MJ Plenge RM 《Nature genetics》2008,40(10):1216-1223
To identify rheumatoid arthritis risk loci in European populations, we conducted a meta-analysis of two published genome-wide association (GWA) studies totaling 3,393 cases and 12,462 controls. We genotyped 31 top-ranked SNPs not previously associated with rheumatoid arthritis in an independent replication of 3,929 autoantibody-positive rheumatoid arthritis cases and 5,807 matched controls from eight separate collections. We identified a common variant at the CD40 gene locus (rs4810485, P = 0.0032 replication, P = 8.2 x 10(-9) overall, OR = 0.87). Along with other associations near TRAF1 (refs. 2,3) and TNFAIP3 (refs. 4,5), this implies a central role for the CD40 signaling pathway in rheumatoid arthritis pathogenesis. We also identified association at the CCL21 gene locus (rs2812378, P = 0.00097 replication, P = 2.8 x 10(-7) overall), a gene involved in lymphocyte trafficking. Finally, we identified evidence of association at four additional gene loci: MMEL1-TNFRSF14 (rs3890745, P = 0.0035 replication, P = 1.1 x 10(-7) overall), CDK6 (rs42041, P = 0.010 replication, P = 4.0 x 10(-6) overall), PRKCQ (rs4750316, P = 0.0078 replication, P = 4.4 x 10(-6) overall), and KIF5A-PIP4K2C (rs1678542, P = 0.0026 replication, P = 8.8 x 10(-8) overall). 相似文献
439.
440.
Giri G Verploegen E Mannsfeld SC Atahan-Evrenk S Kim do H Lee SY Becerril HA Aspuru-Guzik A Toney MF Bao Z 《Nature》2011,480(7378):504-508
Circuits based on organic semiconductors are being actively explored for flexible, transparent and low-cost electronic applications. But to realize such applications, the charge carrier mobilities of solution-processed organic semiconductors must be improved. For inorganic semiconductors, a general method of increasing charge carrier mobility is to introduce strain within the crystal lattice. Here we describe a solution-processing technique for organic semiconductors in which lattice strain is used to increase charge carrier mobilities by introducing greater electron orbital overlap between the component molecules. For organic semiconductors, the spacing between cofacially stacked, conjugated backbones (the π-π stacking distance) greatly influences electron orbital overlap and therefore mobility. Using our method to incrementally introduce lattice strain, we alter the π-π stacking distance of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) from 3.33?? to 3.08??. We believe that 3.08?? is the shortest π-π stacking distance that has been achieved in an organic semiconductor crystal lattice (although a π-π distance of 3.04?? has been achieved through intramolecular bonding). The positive charge carrier (hole) mobility in TIPS-pentacene transistors increased from 0.8?cm(2)?V(-1)?s(-1) for unstrained films to a high mobility of 4.6?cm(2)?V(-1)?s(-1) for a strained film. Using solution processing to modify molecular packing through lattice strain should aid the development of high-performance, low-cost organic semiconducting devices. 相似文献