title: Rapid quantitative analysis of human serum sphingomyelin species using MALDI-TOF mass spectrometry with lipid hydrolase treatment.
abstract: BACKGROUND
  Sphingomyelin (SM) is a key component of extracellular membranes and lipoproteins, and plays roles in cell signaling and as a component of lipoproteins. SM species differ in terms of fatty acid (FA) composition. However, no simple, rapid, quantitative assay for identifying different SM species has yet been reported. In this study, lipid hydrolase treatment and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used to identify serum SM species.
  
  
  METHODS
  Sera were collected from healthy young individuals. To identify SM species, sera were treated with phospholipase A2 and lipoprotein lipase, and lipids were extracted using the standard chloroform/methanol (2/1 v/v) method.
  
  
  RESULTS
  We detected 15 peaks from serum using MALDI-TOF MS, which were assigned to SM species bound with FA components ranging from C15:0 to C24:2. The most prominent serum SM species was SM [C16:0], which accounted for approximately 26% of serum SM. Some SM species contained an odd-carbon FA (C15, C21, and C23), and these accounted for approximately 4% of serum SM. The reproducibility of major SM species within and between application positions on MS-sample plate was CV=3.0%-7.9% and CV=3.1%-6.8%, respectively. The concentration and dilution ratio were linearly related. The SM species composition of 10 healthy young subjects showed a similar profile.
  
  
  CONCLUSIONS
  We developed a rapid, and quantitative method for identifying serum SM species using lipid hydrolase treatment and MALDI-TOF MS. This method will be suitable for clinical laboratory studies to examine the associations between SM species and disease states.
authors.affiliation: Department of Biomedical Laboratory Science, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto 390-0821, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hori
authors.affiliation: Department of Biomedical Laboratory Science, Faculty of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Mine
authors.initials: M
authors.lastname: Yamashita
authors.affiliation: Department of Biomedical Laboratory Science, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto 390-0821, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamaura
authors.affiliation: Department of Biomedical Laboratory Science, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto 390-0821, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Hongo
authors.affiliation: Department of Laboratory Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-0821, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Honda
authors.affiliation: Department of Biomedical Laboratory Science, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto 390-0821, Japan. Electronic address: hiroyan@shinshu-u.ac.jp.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Hidaka
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D006867:Hydrolases / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D012015:Reference Standards; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods* / Q000592:standards; D013109:Sphingomyelins / Q000097:blood* / Q000378:metabolism; D013997:Time Factors; D055815:Young Adult
chemical_list: D013109:Sphingomyelins; D006867:Hydrolases
keywords: Lipoprotein lipase; MALDI-TOF mass spectrometry; Phospholipase A(2); Sphingomyelin