[Influences of Sample Processing on Low-Molecular-Weight Proteome Identified by SELDI]
>>Clin Chem. 2005 Jul 7; [Epub ahead of print]
Influences of Sample Processing on Low-Molecular-Weight Proteome Identified by Surface-Enhanced Laser Desorption/Ionization Mass Spectrometry.
Banks RE, Stanley AJ, Cairns DA, Barrett JH, Clarke P, Thompson D, Selby PJ.
Cancer Research UK Clinical Centre, St James's University Hospital, Leeds, UK.
BACKGROUND: Profiling approaches in proteomics, such as surface-enhanced laser desorption/ionization (SELDI) mass spectrometry, are used in disease marker discovery. The aim of this study was to investigate the potential influence of selected preanalytical factors on the results obtained. METHODS: Plasma samples anticoagulated with EDTA, citrate, or heparin, and serum samples from healthy volunteers were profiled by SELDI on CM10, immobilized metal affinity capture (IMAC) array with copper surface, and H50 chip surfaces. With linear mixed-effects models, we examined the influence of elapsed time between venipuncture and sample separation (immediate to 24 h) and the type of serum tube used (Greiner Vacuette activator, gel serum separator, or plain tubes). We analyzed purified platelets, as well as platelet-poor and platelet-rich plasma samples treated with calcium and/or thrombin to determine the platelet contribution, directly or via the clotting process, to the profiles generated. We then used cluster analysis to identify samples with similar peak profiles. RESULTS: Different plasma types and sera could be distinguished on the basis of cluster analyses of their spectral profiles. Elapsed time between venipuncture and separation of plasma and serum from blood samples altered the profiles obtained, particularly for serum samples and particularly on IMAC chips. The type of serum collection tube also affected the profiles because of differences in clotting time. In vitro manipulation of platelets revealed that specific peaks in IMAC profiles of serum appeared to be derived directly from platelets. Several other peaks, including some of those exhibiting time-dependent changes, arose during the clotting process. CONCLUSION: Preanalytical variables, such as sample handling, can markedly influence results.<<
Again the importance of one protocol for a particular test cannot be overemphasized.
Cheers, Tuck |
