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In-Depth Information
previously described
45
with smaller abscesses
found in the treated animals. Animals were
then sacri
imperative as IMS moves to higher numbers
of samples and higher spatial resolution.
ced, snap frozen, and sectioned in
a whole body cryomacrotome. Prior to each
section being cut, a photograph of the blockface
was taken. About 40 sections were collected per
animal in the region encompassing the kidneys
and subjected to protein IMS. Three-dimensional
volumes were generated of proteins that local-
ized to the abscesses and to normal kidney struc-
tures and were then co-registered through the
use of the optical blockface intermediary to the
MRI volumes. Calgranulin A showed localiza-
tion to the abscesses in the IMS volume and cor-
responded to the observed abscesses in the MRI
volume. A second protein fragment,
CONCLUSIONS AND
PERSPECTIVES
Imaging mass spectrometry has shown wide
applicability in the study of biological systems
allowing for the
in situ
analysis of many classes
of biomolecules. Proteins, peptides, lipids, and
drugs/metabolites have all been successfully
imaged at high spatial resolution with relative
quantitation, providing valuable insight into their
involvement in biological and disease processes.
Although relative quantitation has been clearly
demonstrated, processes necessary to achieve
absolute quantitation are just beginning. IMS has
enabled investigation of biological processes and
has provided insights into better diagnostics,
outcomes, and treatment response, especially in
areas where traditional histology has not been
effective. As the technology and sample prepara-
tion methods advance, IMS is becoming easier to
use in a wide variety of applications in the biolog-
ical andmedical
-globin
residues 2-47, was found to localize to the cortex
of the kidney. This study clearly showed the
ability of IMS to monitor the infection process
and treatment through multimodality imaging
using MRI and IMS.
a
HIGH-SPEED IMAGING
One of the major challenges when moving
to higher spatial resolutions and higher data
volumes as in the case of 3D imaging is the
time necessary to complete the imaging
process. The use of high-repetition-rate lasers
12
and continuous raster sample stages are highly
bene
cityof
this imaging technology brings a very powerful
and enabling tool to these disciplines.
elds. Themolecular speci
Acknowledgments
The authors acknowledge funding from NIH/NIGMS 8P41
GM103391-02 (formerly NIH/NCRR 8P41 RR031461-02),
NIH/NIGMS 5R01 GM058008-13, and the DOD grant
W81XWH-05-1-0179.
cial in achieving high-speed imaging.
This has been recently shown in images
acquired using the new instrument
from
(Virgin Instruments, Inc.).
78
This
mass spectrometer couples a 5 kHz laser repe-
tition rate with continuous raster. Pixel dimen-
sions are determined by the number of shots
per pixel, the stage speed, and the repetition
rate of the laser. By operating the laser at 3
kHz, a stage speed of 5 mm/s, and acquiring
60 shots per pixel, an image of a sagittal rat
brain section (185 mm
2
) consisting of approxi-
mately 19,000 pixels was acquired in under
10 minutes. Such technological advances are
SimulTOF
References
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biological
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and
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e
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(4):606
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