title: Protein glycation, oxidation and nitration adduct residues and free adducts of cerebrospinal fluid in Alzheimer's disease and link to cognitive impairment.
abstract: Increased damage to proteins by glycation, oxidation and nitration has been implicated in neuronal cell death leading to Alzheimer's disease (AD). Protein glycation, oxidation and nitration adducts are consequently formed. Quantitative screening of these adducts in CSF may provide a biochemical indicator for the diagnosis of AD. To assess this, we measured 11 glycation adducts, three oxidation adducts and a nitration adduct, determining both protein adduct residues and free adducts, in CSF samples of age-matched normal healthy subjects (n = 18) and subjects with Alzheimer's disease (n = 32). In CSF protein, the concentrations of 3-nitrotyrosine, N(epsilon)-carboxymethyl-lysine, 3-deoxyglucosone-derived hydroimidazolone and N-formylkynurenine residues were increased in subjects with Alzheimer's disease. In CSF ultrafiltrate, the concentrations of 3-nitrotyrosine, methylglyoxal-derived hydroimidazolone and glyoxal-derived hydroimidazolone free adducts were also increased. The Mini-Mental State Examination (MMSE) score correlated negatively with 3-nitrotyrosine residue concentration (p < 0.05), and the negative correlation with fructosyl-lysine residues just failed to reach significance (p = 0.052). Multiple linear regression gave a regression model of the MMSE score on 3-nitrotyrosine, fructosyl-lysine and N(epsilon)-carboxyethyl-lysine residues with p-values of 0.021, 0.031 and 0.052, respectively. These findings indicate that protein glycation, oxidation and nitration adduct residues and free adducts were increased in the CSF of subjects with Alzheimer's disease. A combination of nitration and glycation adduct estimates of CSF may provide an indicator for the diagnosis of Alzheimer's disease.
authors.affiliation: Department of Biological Sciences, University of Essex, Colchester, Essex, UK.
authors.forename: Naila
authors.initials: N
authors.lastname: Ahmed
authors.forename: Usman
authors.initials: U
authors.lastname: Ahmed
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Thornalley
authors.forename: Klaus
authors.initials: K
authors.lastname: Hager
authors.forename: Gerd
authors.initials: G
authors.lastname: Fleischer
authors.forename: Gerald
authors.initials: G
authors.lastname: Münch
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid* / Q000175:diagnosis / Q000378:metabolism*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002556:Cerebrospinal Fluid Proteins / Q000134:cerebrospinal fluid* / Q000378:metabolism*; D003072:Cognition Disorders / Q000134:cerebrospinal fluid* / Q000175:diagnosis / Q000209:etiology; D005260:Female; D006031:Glycosylation; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000134:cerebrospinal fluid; D008297:Male; D009483:Neuropsychological Tests; D009566:Nitrates / Q000378:metabolism*; D009603:Nitroso Compounds / Q000134:cerebrospinal fluid; D010084:Oxidation-Reduction; D012016:Reference Values; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000134:cerebrospinal fluid
chemical_list: C443112:3-nitrosotyrosine; D015415:Biomarkers; D002556:Cerebrospinal Fluid Proteins; D009566:Nitrates; D009603:Nitroso Compounds; C033186:fructosyl-lysine; D014443:Tyrosine; D008239:Lysine