The SCHC within the HUPO PPP comprises a diverse group of researchers, each investigating various parameters relating to a specific topic. Given the complexity of the blood proteome, collection and handling present a very broad range of specific technical challenges, far too many to be completely investigated in the PPP pilot phase. A list of some of these issues is presented in Tab. 2. The data that follow represent available data contributed from various SCHC member laboratories. The
Tab. 2 List of pre-analytical variables. There are a number of factors that can alter the composition of samples prior to prote-omic analysis. Some ofthese are listed here; these issues can be divided into those relating to patient history, sample collection and handling, and specimen storage.
- Patient information O Gender
O Age O Diet O Genetics
O Needle gauge O Details of blood collection set
O Tourniquet technique O Patient position: seated/standing/lying O Tube order- first versus last
O Blood source: venipuncture or from existing line
- Collection device O Tube or bag
O If tube, glass or plastic O Gel or non-gel separator O Other tube additives O Manufacturer & device information
- Blood derivative and processing
O If plasma, nature of anticoagulant: EDTA, citrate, heparin O If serum, clotting procedure used, and/or type of clot activator O Details of processing: time, protocol, etc.
■ Separation of blood from cells
■ Centrifugation, speed & duration
■ Aliquotting before analysis, and handling/storage of those aliquots, e.g., time and temperature conditions
■ Length of time before analysis
O Frozen before analysis: snap-frozen, e.g., dry ice-ethanol, or slowly cooled, e.g., storage at
-20oC/-80oC? O Elapsed time and temperature, prior to freezing O Short or long-term storage O Storage temperature O Expiration dating O Storage materials: Glass versus plastic O If plastic, type of plastic O Number of freeze/thaw cycles results are based on very defined and specific experiments covering several parameters. They are presented to suggest the scope and tone of the important task of refining collection and handling into a concrete set of recommendations. These experiments and results fall into three broad categories: comparison of sample types, studies of basic sample handling and storage issues, and evaluation of the use of protease inhibitors.
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