4 research outputs found

    PiB-Conjugated, Metal-Based Imaging Probes: Multimodal Approaches for the Visualization of Ī²ā€‘Amyloid Plaques

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    In an effort toward the visualization of Ī²-amyloid plaques by in vivo imaging techniques, we have conjugated an optimized derivative of the Pittsburgh compound B (PiB), a well-established marker of AĪ² plaques, to DO3A-monoamide that is capable of forming stable, noncharged complexes with different trivalent metal ions including Gd<sup>3+</sup> for MRI and <sup>111</sup>In<sup>3+</sup> for SPECT applications. Proton relaxivity measurements evidenced binding of GdĀ­(DO3A-PiB) to the amyloid peptide AĪ²<sub>1ā€“40</sub> and to human serum albumin, resulting in a two- and four-fold relaxivity increase, respectively. Ex vivo immunohistochemical studies showed that the DO3A-PiB complexes selectively target AĪ² plaques on Alzheimerā€™s disease human brain tissue. Ex vivo biodistribution data obtained for the <sup>111</sup>In-analogue pointed to a moderate bloodā€“brain barrier (BBB) penetration in adult male Swiss mice (without amyloid deposits) with 0.36% ID/g in the cortex at 2 min postinjection
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