title: Growth hormone abuse in the horse: preliminary assessment of a mass spectrometric procedure for IGF-1 identification and quantitation.
abstract: Previous studies have shown that insulin-like growth factor 1 (IGF-1) is a promising marker for the detection of growth hormone (GH) abuse in the horse. The significant increases observed with GH administration in comparison to natural levels imply the possibility of setting a threshold level for IGF-1 that would be indicative of GH abuse. Although an immunoradiometric assay (IRMA) has been identified as a reliable screening method, a more specific IGF-1 quantification method needs to be developed for the prosecution of GH abuse by horseracing authorities. This study describes such an HPLC electrospray mass spectrometry (LC/ESI-MS) method that was developed and then assessed for the specific analysis of IGF-1 at the low levels encountered in serum. The structural identity of IGF-1 was confirmed by endoproteinase Asp-N digestion followed by LC/MS and LC/MS/MS characterisation. This was followed by quantification of IGF-1 as the intact molecule against an internal standard.
authors.affiliation: The Laboratory of the Jockey Club of Southern Africa, PO Box 74439, Turffontein 2140, South Africa. schalkdk@iafrica.com
authors.forename: S S
authors.initials: SS
authors.lastname: de Kock
authors.forename: J P
authors.initials: JP
authors.lastname: Rodgers
authors.forename: B C
authors.initials: BC
authors.lastname: Swanepoel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D010450:Endopeptidases / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood* / Q000494:pharmacology; D006736:Horses; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000737:chemistry*; D008666:Metalloendopeptidases; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D015415:Biomarkers; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D010450:Endopeptidases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D008666:Metalloendopeptidases; C058921:endoproteinase Asp-N