Figure A. Molecular structure of diamine-substituted Aβ1-30. Amino acid sequence of Aβ peptides and chemical structure of modified glutamine and asparagine residues
Figure B. Targeting of Diamine and Gadolinium Substituted A-Beta 30 to AD amyloid plaques after intravenous injection.
Labeling of amyloid plaques in APP, PS1 transgenic mouse brain in vivo after exposure for 8 weeks. Fixed, frozen brain sections from a 21-month-old APP, PS1 mouse after intravenous injection with 750 μg of [125I]Aβ40 (A and B), [125I]Aβ30 (C and D), [125I][N-4ab/Q-4ab]Aβ30 (E and F), or [125I]Gd[N-4ab/Q-4ab]Aβ30 (G and H) and after being processed for anti-Aβ IH and emulsion autoradiography. For panels A, C, E, and G (cortex), the scale bar is 50 μm. For panels B, D, F, and H (CA1 subfield of the hippocampus), the scale bar is 50 μm.
Figure C. PUT-Gd-Ab-injected APP-PS1 mouse.
(A) Thioflavin S histologic section, (B) T2W MR image, and (C) T1W MR image at matched anatomic locations in the region of the hippocampus. The top of the histologic section is missing in (A) because entire section did not fit within the field of view of the confocal microscope. (D-F) Higher magnifications of the portion of the parent image above containing the arrows. Plaques appear dark on the T2W images and bright on the T1W image indicating accelerated T2 and T1 relaxation, respectively, in plaque relative to normal tissue. Arrows highlight five plaques. Note that the spatial distribution of the plaques in the T2W and T1W images matches that of the corresponding numbered plaques in the thioflavin S section precisely. This precise level of agreement in the pattern of plaque locations between the histologic and the MR sections could not have occurred by chance, and verifies that the plaques in the histologic section are accurately reproduced in the MR images. The bright area on the top right hand corner of the T1W image is an aliasing artifact. The low frequency modulation in the background signal intensity of the T1W image (also present on the T2W image but less apparent) is due to B1 non-uniformity. It would have been possible to digitally filter the MR images to remove the effect of field inhomogeneity from the images. We elected to not perform any post hoc digital image enhancements in order to accurately portray the tissue contrast properties of the unaltered MR images in each experiment. Scale bars, 250 µm in (A-C), 100 µm in (D-F).
Figure D. Three- way correlation in a 26 month AD mouse. Panels A, C, and E are full FOV and panels B, D, and F illustrate a magnified sub-sampled area centered on the hippocampus, of the parent image to its left. The numbered arrows point to identical spatial coordinate positions in the common space of the three spatially registered volumes (in vivo, ex vivo, histological) using a linked cursor system. Spatially matched in vivo (A,B), ex vivo (C,D), and histological sections (E,F) conclusively demonstrate that the dark areas seen in vivo do indeed represent plaques. (E) Scale bar = 500 μm. (F) Scale bar = 200 μm. Plaque sharpness in vivo approaches, but is clearly inferior to that obtained on ex vivo MRI.