title: Development and validation of an LC-MS/MS assay for the quantification of the trans-methylation pathway intermediates S-adenosylmethionine and S-adenosylhomocysteine in human plasma.
abstract: BACKGROUND
  Although increased levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) have been implicated as markers for renal and vascular dysfunction, until now there have been no studies investigating their association with clinical post-transplant events such as organ rejection and immunosuppressant nephrotoxicity.
  
  
  METHODS
  A newly developed and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the quantification of SAM and SAH in human EDTA plasma was used for a clinical proof-of-concept pilot study. Retrospective analysis was performed using samples from a longitudinal clinical study following de novo kidney transplant patients for the first year (n=16).
  
  
  RESULTS
  The ranges of reliable response were 8 to 1024 nmol/l for SAM and 16 to 1024 nmol/l for SAH. The inter-day accuracies were 96.7-103.9% and 97.9-99.3% for SAM and SAH, respectively. Inter-day imprecisions were 8.1-9.1% and 8.4-9.8%. The total assay run time was 5 min. SAM and SAH concentrations were significantly elevated in renal transplant patients preceding documented acute rejection and nephrotoxicity events when compared to healthy controls (n=8) as well as transplant patients void of allograft dysfunction (n=8).
  
  
  CONCLUSIONS
  The LC-MS/MS assay will provide the basis for further large-scale clinical studies to explore these thiol metabolites as molecular markers for the management of renal transplant patients.
authors.affiliation: Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045-7503, United States. jacek.klepacki@ucdenver.edu
authors.forename: Jacek
authors.initials: J
authors.lastname: Klepacki
authors.forename: Nina
authors.initials: N
authors.lastname: Brunner
authors.forename: Volker
authors.initials: V
authors.lastname: Schmitz
authors.forename: Jelena
authors.initials: J
authors.lastname: Klawitter
authors.forename: Uwe
authors.initials: U
authors.lastname: Christians
authors.forename: Jost
authors.initials: J
authors.lastname: Klawitter
mesh_terms: D000328:Adult; D005260:Female; D006084:Graft Rejection / Q000097:blood* / Q000175:diagnosis*; D006801:Humans; D016030:Kidney Transplantation; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011379:Prognosis; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012435:S-Adenosylhomocysteine / Q000097:blood*; D012436:S-Adenosylmethionine / Q000097:blood*
chemical_list: D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine