title: Quantitative analysis of amyloid-beta peptides in cerebrospinal fluid using immunoprecipitation and MALDI-Tof mass spectrometry.
abstract: Immunoprecipitation (IP) combined with matrix-assisted laser desorption ionization (MALDI) time of flight (Tof) mass spectrometry has been used to develop quantitative assays for amyloid-beta (Abeta) peptides in cerebrospinal fluid (CSF). Inclusion of (15)N labelled standard peptides allows for absolute quantification of multiple Abeta isoforms in individual samples. Characterization of variability associated with all steps of the assay indicated that the IP step is the single largest contributor to overall variability. Optimization of the assay resulted in overall coefficient of variation <or=8% with high agreement to an Abeta(1-40) and Abeta(1-42) ELISA assay. Application of the MALDI-Tof assay to CSF obtained from healthy volunteers and Alzheimer's disease patients indicated statistically significant 43% lower levels of Abeta(1-42) in the AD group (P = 0.0025).
authors.affiliation: Integrative Biology Division, Lilly Research Laboratories, Greenfield, IN 46140, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Gelfanova
authors.forename: Richard E
authors.initials: RE
authors.lastname: Higgs
authors.forename: Robert A
authors.initials: RA
authors.lastname: Dean
authors.forename: David M
authors.initials: DM
authors.lastname: Holtzman
authors.forename: Martin R
authors.initials: MR
authors.lastname: Farlow
authors.forename: Eric R
authors.initials: ER
authors.lastname: Siemers
authors.forename: Amechand
authors.initials: A
authors.lastname: Boodhoo
authors.forename: Yue-Wei
authors.initials: YW
authors.lastname: Qian
authors.forename: Xiaohua
authors.initials: X
authors.lastname: He
authors.forename: Zhaoyan
authors.initials: Z
authors.lastname: Jin
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Fisher
authors.forename: Karen L
authors.initials: KL
authors.lastname: Cox
authors.forename: John E
authors.initials: JE
authors.lastname: Hale
mesh_terms: D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D015415:Biomarkers / Q000032:analysis / Q000134:cerebrospinal fluid; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D047468:Immunoprecipitation; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*; D020033:Protein Isoforms / Q000134:cerebrospinal fluid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; D020033:Protein Isoforms