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P3‐216: Plasma acetylcholinesterase activity is correlated with intracerebral beta‐amyloid load measured in vivo
Author(s) -
Alkalay Adi,
Rabinovici Gil D.,
Zimmerman Gabriel,
Agarwal Neha,
Kaufer Daniela,
Miller Bruce L.,
Jagust William W.,
Soreq Hermona
Publication year - 2010
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2010.05.1715
Subject(s) - acetylcholinesterase , donepezil , pittsburgh compound b , butyrylcholinesterase , medicine , cholinesterase , progressive supranuclear palsy , galantamine , cholinergic , endocrinology , population , dementia , pathology , psychology , chemistry , aché , biochemistry , disease , enzyme , environmental health
Background: Due to its proximity to the brain, Cerebrospinal fluid (CSF) is a perfect source to search for new biomarkers to improve early diagnosis of neurological diseases. Standardization of pre-analytical handling of the sample is important to obtain acceptable analytical quality. Preanalytical in vitro factors occur before the final analysis and include both the collection of the specimen and the processing of it. The aim of the present study was to study the influence of some common preanalytical procedures on the CSF proteome analyzed by immunochemical techniques and SELDI-TOF MS. We aimed to clarify the effects of protease inhibitors, repeated freeze/thaw cycles, storage time and temperatures on the CSF proteome. Methods: CSF samples from ten patients were aliquoted into individual polypropylene tubes with or without protease inhibitor cocktail for general use from SigmaAldrich. The tubes were immediately stored at -80 C. The samples were subsequently subjected to one, two or three freeze/thaw cycles before analysis. Individual immunoassays were used for the measurement of CSF concentrations Ab1-42, Tau, Phosphorylated Tau and Cystatin C. Results: Ab1-42 and Cystatin C were not susceptible to up to three freeze/thaw cycles. There was a significant difference in the concentrations of both Tau and Phosphorylated Tau after three freeze/thaw cycles when protease inhibitors were not added, ANOVA p values were 0.014 and < 0.0001, respectively. The most striking difference was seen in Phosphorylated Tau where significant higher concentrations were detected in the samples without protease inhibitor. Conclusions: Standarization of CSF collection protocols is of outmost importance, especially in the cases where samples have been collected and stored at different centres. Our study shows that Ab1-42 and Cystatin C are not susceptible to up to three freeze/thaw cycles. In order to avoid false positive results, Tau and Phosphorylated Tau should not be analyzed in samples that have been frozen and thawed repeatedly. We recommend aliquoting the CSF immediately after sampling and centrifugation, and storage at -80 degrees Celsius without the addition of protease inhibitors.