title: Evaluation of the orthogonal projection on latent structure model limitations caused by chemical shift variability and improved visualization of biomarker changes in 1H NMR spectroscopic metabonomic studies.
abstract: In general, applications of metabonomics using biofluid NMR spectroscopic analysis for probing abnormal biochemical profiles in disease or due to toxicity have all relied on the use of chemometric techniques for sample classification. However, the well-known variability of some chemical shifts in 1H NMR spectra of biofluids due to environmental differences such as pH variation, when coupled with the large number of variables in such spectra, has led to the situation where it is necessary to reduce the size of the spectra or to attempt to align the shifting peaks, to get more robust and interpretable chemometric models. Here, a new approach that avoids this problem is demonstrated and shows that, moreover, inclusion of variable peak position data can be beneficial and can lead to useful biochemical information. The interpretation of chemometric models using combined back-scaled loading plots and variable weights demonstrates that this peak position variation can be handled successfully and also often provides additional information on the physicochemical variations in metabonomic data sets.
authors.affiliation: Biological Chemistry, Biomedical Sciences Division, Faculty of Medicine, Imperial College London, South Kensington, London SW7 2AZ, UK. o.cloarec@imperial.ac.uk
authors.forename: Olivier
authors.initials: O
authors.lastname: Cloarec
authors.forename: Marc E
authors.initials: ME
authors.lastname: Dumas
authors.forename: Johan
authors.initials: J
authors.lastname: Trygg
authors.forename: Andrew
authors.initials: A
authors.lastname: Craig
authors.forename: Richard H
authors.initials: RH
authors.lastname: Barton
authors.forename: John C
authors.initials: JC
authors.lastname: Lindon
authors.forename: Jeremy K
authors.initials: JK
authors.lastname: Nicholson
authors.forename: Elaine
authors.initials: E
authors.lastname: Holmes
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000652:urine; D000272:Adipates / Q000652:urine; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015415:Biomarkers / Q000032:analysis* / Q000652:urine; D019343:Citric Acid / Q000652:urine; D003198:Computer Simulation; D003404:Creatinine / Q000652:urine; D001330:Electronic Data Processing; D006859:Hydrogen; D019344:Lactic Acid / Q000652:urine; D008297:Male; D008627:Mercuric Chloride / Q000633:toxicity; D008660:Metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013654:Taurine / Q000652:urine
chemical_list: D000272:Adipates; D000596:Amino Acids; D015415:Biomarkers; D013654:Taurine; D019343:Citric Acid; D019344:Lactic Acid; D008627:Mercuric Chloride; C029900:adipic acid; D006859:Hydrogen; D003404:Creatinine; D020155:3-Hydroxybutyric Acid