title: Improved pharmacodynamic assay for dihydropyrimidine dehydrogenase activity in peripheral blood mononuclear cells.
abstract: BACKGROUND
  Dihydropyrimidine dehydrogenase (DPD) activity determination in peripheral blood mononuclear cells of DPD deficient patients was hitherto inaccurate due to hemoglobin (Hb) contamination. We developed an improved method for accurate measurement of DPD activity in patients.
  
  
  RESULTS
  DPD activity was determined by HPLC with online radioisotope detection using liquid scintillation counting. Hb was determined spectrophotometrically. Method accuracy and precision were significantly improved by using cumulative area of all peaks as IS. Peripheral blood mononuclear cell lysates from DPD deficient patients were highly contaminated with on average 23.3% (range 2.7-51%) of Hb resulting in up to twofold underestimated DPD activity. DPD activities were corrected for Hb contamination. The method was validated and showed good long-term sample stability.
  
  
  CONCLUSIONS
  This method has increased specificity allowing accurate identification of DPD deficient patients.
authors.affiliation: Division of Molecular Pathology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
authors.forename: Dick
authors.initials: D
authors.lastname: Pluim
authors.forename: Bart A W
authors.initials: BA
authors.lastname: Jacobs
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Deenen
authors.forename: Anneloes E M
authors.initials: AE
authors.lastname: Ruijter
authors.forename: Robin M J M
authors.initials: RM
authors.lastname: van Geel
authors.forename: Artur M
authors.initials: AM
authors.lastname: Burylo
authors.forename: Didier
authors.initials: D
authors.lastname: Meulendijks
authors.forename: Jos H
authors.initials: JH
authors.lastname: Beijnen
authors.forename: Jan H M
authors.initials: JH
authors.lastname: Schellens
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear
chemical_list: D042943:Dihydrouracil Dehydrogenase (NADP)