D erythro sphingosine

Alexa-488-conjugated Annexin-V and MitoTracker Green were purchased from Thermo Fisher Scientific (Waltham, MA). D-erythro-sphingosine was from Cayman Chemical Company (Ann Arbor, MI). FM4-64 was purchased from Life Technologies (Carlsbad, CA). All other fine chemicals were from Sigma-Aldrich (St. Louis, MO). Recombinant Cy3-labeled verotoxin B subunit was provided by Dr. C. Lingwood (Hospital for Sick Children, Toronto, Canada). Short-chain PtdSer, 1,2-didecanoyl-sn-glycero-3-[phospho-l-serine] (DDPS 10:0) was purchased from Avanti Polar Lipids (Alabaster, USA).

LC-MS grade solvents/mobile phase additives and analyte standards were purchased from Sigma-Aldrich (Oakville, ON, Canada) unless stated otherwise. ACTH (1–39) was obtained from Anaspec (Fremont, CA, USA). Norepinephrine (d₆), cholic acid (d₄), epinephrine (d₃), dopamine (d₄), melatonin (d₄), 4-aminobutanoic acid (d₆) and phenylalanine (d₅) were obtained from CDN Isotopes (Point-Claire, QC, Canada), while ¹³C₆- thyroxine was purchased from Toronto Research Chemicals (Toronto, ON, Canada). MTBE was bought from Fisher Scientific (Toronto, ON, Canada), while all phospholipids were obtained from Avanti Polar Lipids (Alabaster, Alabama, USA). Kynurenine and D-erythro-sphingosine (further mentioned as sphingosine for brevity) were purchased from Cayman Chemicals (Ann Arbor, MI, USA). Solid stationary phases (PEP2, ODS-C18 and divinylbenzene conjugated with sulfonic acid and quaternary amine moieties (IEX)) were obtained from Agela Technologies (Wilmington, DE, USA). Citrated pooled human plasma was obtained from Bioreclamation (Baltimore, MD, USA) and was collected in accordance with the company’s code of ethics. All reagents were of analytical or higher grade.