- Synthesis and evaluation of 11C-labeled imidazo[2,1-b] benzothiazoles (IBTs) as PET tracers for imaging β-amyloid plaques in Alzheimer's disease
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We report a novel series of 11C-labeled imidazo[2,1-b] benzothiazoles (IBTs) as tracers for imaging of cerebral β-amyloid (Aβ) deposits in patients with Alzheimer's disease (AD) by means of positron emission tomography (PET). From a series of 11 compounds, candidates were identified to have a high binding affinity for Aβ. Selected compounds were prepared as O- or N-[11C]methyl derivatives and shown to have a high initial brain uptake in wild-type mice (range 1.9-9.2% I.D./g at 5 min). 2-(p-[11C]Methylaminophenyl)-7-methoxyimidazo[2,1-b] benzothiazole ([11C]5) was identified as a lead based on the combined favorable properties of high initial brain uptake, rapid clearance from normal brain, and high in vitro affinity for Aβ1-40 (Ki = 3.5 nM) and Aβ1-42 (5.8 nM), which were superior to the Pittsburgh compound B (1a). In an APP/PS1 mouse model of AD (Tg), we demonstrate a specific uptake of [11C]5 in Aβ-containing telencephalic brain regions by means of small-animal PET that was confirmed by regional brain biodistribution, ex vivo autoradiography, and immunohistochemistry. Analysis of brain sections of Tg mice receiving a single bolus injection of [11C]5 and [ 3H]1a together revealed that the tracers bind to Aβ plaques in the brain of Tg mice in a comparable pattern. Taken together, these data suggest that IBTs represent useful PET imaging agents for high-sensitivity detection of Aβ plaques.
- Yousefi, Behrooz H.,Manook, André,Drzezga, Alexander,Reutern, Boris V.,Schwaiger, Markus,Wester, Hans-Jürgen,Henriksen, Gjermund
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p. 949 - 956
(2011/04/24)
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- A novel 18F-labeled imidazo[2,1- b ]benzothiazole (IBT) for high-contrast PET imaging of β-amyloid plaques
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18F-labeled imidazo[2,1-b]benzothiazole ([18F]8) was synthesized and evaluated as a tracer for cerebral β-amyloid deposits (Aβ) by means of positron emission tomography (PET). [18F]8 exhibits a high affinity to Aβ and suit
- Yousefi, Behrooz H.,Drzezga, Alexander,Reutern, Boris Von,Manook, Andre,Schwaiger, Markus,Wester, Hans-Juergen,Henriksen, Gjermund
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p. 673 - 677
(2011/11/06)
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