Browsing by Author "Guenther, I"

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    In vivo quantification of monoamine oxidase A in baboon brain: a PET study using [C-11]befloxatone and the multi-injection approach.
    (Nature Publishing Group, 2010-04-01) Bottlaender, MA; Valette, H; Delforge, J; Saba, W; Guenther, I; Curet, O; George, P; Dollé, F; Grégoire, MC
    [C-11]befloxatone is a high-affinity, reversible, and selective radioligand for the in vivo visualization of the monoamine oxidase A (MAO-A) binding sites using positron emission tomography (PET). The multi-injection approach was used to study in baboons the interactions between the MAO-A binding sites and [C-11] befloxatone. The model included four compartments and seven parameters. The arterial plasma concentration, corrected for metabolites, was used as input function. The experimental protocol-three injections of labeled and/or unlabeled befloxatone-allowed the evaluation of all the model parameters from a single PET experiment. In particular, the brain regional concentrations of the MAO-A binding sites (B-max(')) and the apparent in vivo befloxatone affinity (K-d) were estimated in vivo for the first time. A high binding site density was found in almost all the brain structures (170 +/- 39 and 194 +/- 26 pmol/mL in the frontal cortex and striata, respectively, n = 5). The cerebellum presented the lowest binding site density (66 +/- 13 pmol/mL). Apparent affinity was found to be similar in all structures (KdVR = 6.4 +/- 1.5 nmol/L). This study is the first PET-based estimation of the B-max of an enzyme. © 2010, Nature Publishing Group.