Biology Reference
In-Depth Information
Even a live mouse has been subjected to MAS,
albeit at an ultralow speed of 1.5 Hz.
125
The
1
H
line widths obtained with a specialized pulse
sequence was a factor of 4.6 sharper compared
to a stationary mouse.
Ex vivo analysis of intact tissues via HR-MAS
to study cellular metabolism is the closest to
obtaining in vivo tissue physiology. The spectro-
scopic result can be directly correlated with
tissue disease status.
Figure 5
shows a represen-
tative region of the HR-MAS of benign and
malignant colon tissues from the same patient.
126
The cancer tissue has higher levels of lactate,
glycine, taurine, PC, and choline and lower
levels of myo-inositol, scyllo-inositol, and GPC.
An excellent review of HR-MAS NMR spectros-
copy to study cancer metabolism has been
presented by Moestue et al.
114
The authors
surveyed studies of numerous tissue types and
highlight
Similar to studies on whole serum and
plasma, relaxation and diffusion edited experi-
ments are used to selectively detect metabolites
or macromolecules. In the original experiment
by Cheng et al., the CPMG pulse sequence
segment
[90-(
-180-
)
n
-acquire] was used as
s
s
aT
2
-
used was an exact
multiple of the rotor rotation period (rotor-
synchronized).
124
In general, homonuclear and
heteronuclear 1D and 2D experiments for
liquid-state NMR are all applicable to
HR-MAS studies.
127
For the 2D TOCSY experi-
ment, use of adiabatic (WURST-2) mixing
sequences with rotor synchronization resulted
in better signal to noise.
128,129
Andronesi et al.
optimized the 2D TOCSY experiment equiva-
lent from solid-state NMR spectroscopy, the
2D TOBSY (total through bond correlation
spectroscopy) pulse sequence, to achieve 20%
to 50% higher
lter, and the delay
s
findings in choline metabolism, glycol-
ysis, amino acids, and lipid metabolism.
sensitivity enhancement
in
HR-MAS.
130
FIGURE 5
Representative
1
H HR MAS spectra (2.8
e
4.3 ppm) and corresponding histopathologic sections of (A) benign
and (B) malignant colon tissues from the same patient. The histopathology of the corresponding normal mucosa shows glands
closely arranged with a high density of goblet cells. The cancer tissue has malignant glands surrounded by desmoplastic
stromal tissue. (Adapted with permission from reference #126. Copyright 2011 American Chemical Society.)
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