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Variable scaling alters the covariance structure of data, affecting the outcome of multivariate analysis and calibration. Here we present a new method, variable stability (VAST) scaling, which weights each variable according to a metric of its stability. The beneficial effect of VAST scaling is demonstrated for a data set of 1H NMR spectra of urine acquired as part of a metabonomic study into the effects of unilateral nephrectomy in an animal model. The application of VAST scaling improved the class distinction and predictive power of partial least squares discriminant analysis (PLS-DA) models. The effects of other data scaling and pre-processing methods, such as orthogonal signal correction (OSC), were also tested. VAST scaling produced the most robust models in terms of class prediction, outperforming OSC in this aspect. As a result the subtle, but consistent, metabolic perturbation caused by unilateral nephrectomy could be accurately characterised despite the presence of much greater biological differences caused by normal physiological variation. VAST scaling presents itself as an interpretable, robust and easily implemented data treatment for the enhancement of multivariate data analysis.  相似文献
代谢组学及其在微生物领域的研究进展   总被引:5,自引:0,他引:5  
代谢组学、基因组学和蛋白质组学是系统生物学研究的重要组成部分。本文在文献和作者本人研究的基础上,对代谢组学的产生和技术平台及其在环境微生物领域的研究进展进行了评述。  相似文献
Wang J  Yuan Z  Kong H  Li Y  Lu X  Xu G 《色谱》2012,30(1):8-13
将代谢组学的方法用于研究黄连治疗II型糖尿病的机理。II型糖尿病造模采用对大鼠灌胃脂肪乳并腹腔注射40 mg/kg链脲佐菌素的方法,大鼠分为正常组、模型组、黄连给药治疗组(10 g/kg)、二甲双胍给药治疗组(0.08 g/kg)。大鼠给药30天后,采集血样用于生化指标的检测,采集24 h尿样用于代谢组学的分析。与模型组相比,糖尿病大鼠给药黄连30天后,空腹血糖值(FBG)显著降低了59.26%,总胆固醇(TC)降低了58.66%,甘油三酯(TG)降低了42.18%。采用气相色谱-质谱联用技术(GC-MS)对大鼠尿样中的内源性物质进行了相对含量测定,主成分分析结果表明,正常组与模型组显著分离,黄连组处于正常组与模型组之间,更接近于正常组。发现12个代谢物与糖尿病有关,包括4-甲基苯酚、苯甲酸、氨基丙二酸等。给药黄连后,其中的7个代谢物发生显著性回调,与氧化应激状态相关的氨基丙二酸和L-抗坏血酸出现向正常组显著性调节的趋势。这些结果表明,黄连不仅具有降糖和降血脂的作用,而且具有抗氧化作用,在一定程度上可能会抑制糖尿病合并症的发生和发展。  相似文献
Ion mobility-mass spectrometry   总被引:3,自引:0,他引:3  
This review article compares and contrasts various types of ion mobility-mass spectrometers available today and describes their advantages for application to a wide range of analytes. Ion mobility spectrometry (IMS), when coupled with mass spectrometry, offers value-added data not possible from mass spectra alone. Separation of isomers, isobars, and conformers; reduction of chemical noise; and measurement of ion size are possible with the addition of ion mobility cells to mass spectrometers. In addition, structurally similar ions and ions of the same charge state can be separated into families of ions which appear along a unique mass-mobility correlation line. This review describes the four methods of ion mobility separation currently used with mass spectrometry. They are (1) drift-time ion mobility spectrometry (DTIMS), (2) aspiration ion mobility spectrometry (AIMS), (3) differential-mobility spectrometry (DMS) which is also called field-asymmetric waveform ion mobility spectrometry (FAIMS) and (4) traveling-wave ion mobility spectrometry (TWIMS). DTIMS provides the highest IMS resolving power and is the only IMS method which can directly measure collision cross-sections. AIMS is a low resolution mobility separation method but can monitor ions in a continuous manner. DMS and FAIMS offer continuous-ion monitoring capability as well as orthogonal ion mobility separation in which high-separation selectivity can be achieved. TWIMS is a novel method of IMS with a low resolving power but has good sensitivity and is well intergrated into a commercial mass spectrometer. One hundred and sixty references on ion mobility-mass spectrometry (IMMS) are provided.  相似文献
本文描述了一种基于液相色谱-质谱技术(LC-MS)的代谢组学发现疾病潜在标志物的方法.该方法利用LC-MS获得代谢指纹图谱,并通过多种统计分析方法对产生的海量数据进行分析,最终筛选出潜在标志物.数据分析过程包括:通过归一化、修正80%规则、数据集分割和数据缩放等方法对数据集进行预处理 通过正交校正的偏最小二乘(OPLS)模式识别方法对样品进行分型 根据模型的变量重要性因子(VIP值)、非参数检验结果和z值筛选潜在标志物.以宫颈癌血清样本为例,应用上述方法,15个变量被确认为潜在标志物,操作者接受曲线(ROC)下的面积为0.667~0.956.经过相关性分析和结构鉴定,发现这15个变量来自9个化合物.其中7个化合物被鉴定为色氨酸、硬脂酸、花生四烯酸、溶血磷脂酰胆碱(0:0/16:0,16:0/0:0,18:1/0:0和18:0/0:0),说明在宫颈癌中花生四烯酸和溶血磷脂酰胆碱的代谢发生异常.  相似文献
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS) is the best MS technology for obtaining exact mass measurements owing to its great resolution and accuracy, and several outstanding FT-ICR/MS-based metabolomics approaches have been reported. A reliable annotation scheme is needed to deal with direct-infusion FT-ICR/MS metabolic profiling. Correlation analyses can help us not only uncover relations between the ions but also annotate the ions originated from identical metabolites (metabolite derivative ions). In the present study, we propose a procedure for metabolite annotation on direct-infusion FT-ICR/MS by taking into consideration the classification of metabolite-derived ions using correlation analyses. Integrated analysis based on information of isotope relations, fragmentation patterns by MS/MS analysis, co-occurring metabolites, and database searches (KNApSAcK and KEGG) can make it possible to annotate ions as metabolites and estimate cellular conditions based on metabolite composition. A total of 220 detected ions were classified into 174 metabolite derivative groups and 72 ions were assigned to candidate metabolites in the present work. Finally, metabolic profiling has been able to distinguish between the growth stages with the aid of PCA. The constructed model using PLS regression for OD600 values as a function of metabolic profiles is very useful for identifying to what degree the ions contribute to the growth stages. Ten phospholipids which largely influence the constructed model are highly abundant in the cells. Our analyses reveal that global modification of those phospholipids occurs as E. coli enters the stationary phase. Thus, the integrated approach involving correlation analyses, metabolic profiling, and database searching is efficient for high-throughput metabolomics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献
小鼠血清中内源性代谢物的GC/TOF-MS分析   总被引:1,自引:0,他引:1       下载免费PDF全文
采用气相色谱/飞行时间质谱(GC/TOF-MS)联用仪建立了小鼠血清的代谢组学分析方法. 通过对硅烷化试剂的优化和去卷积分析, 共检测到269个峰, 其中相似度在800以上的代谢产物有46个; 以核糖醇为内标, 任意选取18种内源性代谢产物考察此方法的精密度和稳定性, 并通过14种标准氨基酸的混标溶液进行定量分析考察本方法的线性关系. 结果表明, 14种氨基酸在2.78~113.20 ng/ SymbolmA@ L浓度范围内线性关系良好; 18种内源性代谢产物的变异系数均在15%以内, 具有较好的稳定性; 并利用8种标准单糖, 通过肟化反应解决了糖在多个位置出峰的难点. 该方法可用于代谢组学研究, 并通过相关数据处理找出生物标志物, 为疾病诊断提供了新的思路.  相似文献
In this study, the potential of high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (HPLC–QTOFMS) for metabolomic profiling of red wine samples was examined. Fifty one wines representing three varieties (Cabernet Sauvignon, Merlot, and Pinot Noir) of various geographical origins were sourced from the European and US retail market. To find compounds detected in analyzed samples, an automated compound (feature) extraction algorithm was employed for processing background subtracted single MS data. Stepwise reduction of the data dimensionality was followed by principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) which were employed to explore the structure of the data and construct classification models. The validated PLS-DA model based on data recorded in positive ionization mode enabled correct classification of 96% of samples. Determination of molecular formula and tentative identification of marker compound was carried out using accurate mass measurement of full single MS spectra. Additional information was obtained by correlating the fragments obtained by MS/MS accurate mass spectra using the QTOF with collision induced dissociation (CID) of precursor ions.  相似文献
Mass spectrometry-based metabolomics applied to the chemical safety of food   总被引:1,自引:0,他引:1  
Mass spectrometry (MS)-based metabolomics is emerging as an important field of research in many scientific areas, including chemical safety of food. A particular strength of this approach is its potential to reveal some physiological effects induced by complex mixtures of chemicals present at trace concentrations. The limitations of other analytical approaches currently employed to detect low-dose and mixture effects of chemicals make detection very problematic. Besides this basic technical challenge, numerous analytical choices have to be made at each step of a metabolomics study, and each step can have a direct impact on the final results obtained and their interpretation (i.e. sample preparation, sample introduction, ionization, signal acquisition, data processing, and data analysis). As the application of metabolomics to chemical analysis of food is still in its infancy, no consensus has yet been reached on defining many of these important parameters. In this context, the aim of the present study is to review all these aspects of MS-based approaches to metabolomics, and to give a comprehensive, critical overview of the current state of the art, possible pitfalls, and future challenges and trends linked to this emerging field.  相似文献
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