Brain tissue analysis

Methyl parathion was determined in dog and human serum using a benzene extraction procedure followed by GC/FID detection (Braeckman et al. 1980, 1983 DePotter et al. 1978). An alkali flame FID (nitrogen-phosphorus) detector increased the specificity of FID for the organophosphorus pesticides. The detection limit was in the low ppb (pg/L). In a comparison of rat blood and brain tissue samples analyzed by both GC/FPD and GC/FID, Gabica et al. (1971) found that GC/FPD provided better specificity. The minimum detectable level for both techniques was 3.0 ppb, but GC/FPD was more selective. The EPA-recommended method for analysis of low levels (<0.1 ppm) of methyl parathion in tissue, blood, and urine is GC/FPD for phosphorus (EPA 1980d). Methyl parathion is not thermally stable above 120 °C (Keith and Walters 1985). 

Gabica JJ, Wyllie J, Watson M, et al. 1971. Example of flame photometric analysis for methyl parathion in rat whole blood and brain tissue. Anal Chem 43 1102-1105. 

LR white embedding allows a multi-method approach to the analysis of brain tissue from patients with Alzheimer s disease. Histochem. J. 22, 257-268. 

Based on the described neuroanatomy, the three key matrices for evaluating compound concentrations to determine the extent and/or rate of CNS penetration are blood, CSF, and brain tissue. Due to the nearly universal analysis of plasma to determine systemic concentrations of small molecules, total plasma compound concentration (Cp) will henceforth be substituted for total blood concentration, which is the product of Cp and compound blood-to-plasma ratio. 

Rahimi F, Shepherd CE, Halliday GM, et al. Antigen-epitope retrieval to facilitate proteomic analysis of formalin-fixed archival brain tissue. Anal. Chem. 2006 78 7216-7221. 

Hunter SB, Varma V, Shehata B, et al. Apolipoprotein D expression in primary brain tumors analysis by quantitative RT-PCR in formalin-fixed, paraffin-embedded tissue. J. Histochem. Cytochem. 2005 53 963-969. 

Examples of specific methods important to neurochemists include separation and quantification of R- and S-fluoxetine and R- and S-norfluoxetine in brain tissue and body fluids using derivatization with (—)-(S)-N-(trifluoracetyl)prolyl chloride, a chiral derivatizing agent (Torok-Both et al., 1992 Aspeslet et al., 1994). A similar method has been used to separate the enantiomers of 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) (Hegadoren et al., 1993). Eluoxetine and norfluoxetine enantiomers have also been separated on a chiral column in series with a nonchiral column with NPD detections (Ulrich, 2003). Reviews of the analysis of enantiomers of several drugs of abuse are available (Jirovsky et al., 1998 Tao and Zeng, 2002 Liu and Liu, 2002). 

Wong JTF, Paetsch PR, Baker GB, Greenshaw AJ, Coutts RT. 1990b. A rapid procedure for the analysis of phenylalanine in brain tissue utilizing electron-capture gas chromatography. J Neurosci Methods 32 105. 

Numerous assays are also available in the literature for analysis of biogenic amines and their acid metabolites in brain tissue. For example, Chi and colleagues (1999) developed a rapid and sensitive assay for analyzing NE, DA, 5-HT, 5-hydroxyindole-3-acetic acid (5-HIAA), and homovanilHc acid (HVA) in rat brain. The assay used a C18 column (150 x 4.6 mm) coupled to an amperometric electrochemical detector. The mobile phase consisted of a phosphate buffer (pH 4.75) and octane sulphonic acid as an ion-pair reagent in acetonitrile. The sensitivity of the analytes reported was 3-8 pg on column. 

NDA derivatization has also been automated for analysis of amino acids in brain tissue and microdialysates (Shah et al, 1999). NDA reacts with primary amines in the presence of cyanide to form a highly stable N-substituted l-cyanobenz[/] isoindole (GBI) derivative. Addition of a nucleophile, such as cyanide, hydrogen sulphite, isothiocyanate, or 2-mercaptoethanol, is essential for the formation of the derivative. 

Shah AJ, de Biasi V, Taylor SG, Roberts C, Hemmati P, et al. 1999. Development of a protocol for the automated analysis of amino acids in brain tissue samples and microdialy-sates. J Chromatogr B 735 133-140. 

Carboni L, Piubelli C, Righetti PG, Jansson B, Domenici E. 2002. Proteomic analysis of rat brain tissue comparison of protocols for two-dimensional gel electrophoresis analysis based on different solubilizing agents. Electrophoresis 23 ... 

Pierson J, Norris JL, Aerni HR, Svenningsson P, Caprioli RM, et al. 2004. Molecular profiling of experimental Parkinson s disease direct analysis of peptides and proteins on brain tissue sections by MALDI mass spectrometry. J Proteome... 

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