All chemicals used were of the highest purity, and reagents used were of LC-MS grade. All chemicals for the metabolomics studies (L-phenylalanine, phenylpyruvic acid, xanthurenic acid, decanoylcarnitine, sebacic acid, L-tysorine, L-glutamic acid, taurine, succinic acid, creatinine, L-carnitine, pyroglutamic acid, eicosapentaenoic acid, linoleic acid, arachidonic acid, uric acid and citric acid) were purchased from Sigma-Aldrich® (St. Louis, MO). Sphinganine-1-phosphate was purchased from Avanti® Polar Lipids, Inc. (Alabaster, AL), N-decanoyglycine from Hit2Lead (San Diego, CA) and decanoylcarnitine from Tocris Bioscience (Bristol, UK). Standards for lipidomics have been previously described elsewhere (9 (link), 28 ) and covered all broad lipid classes.