th  - 1987 - 51st ENC Conference

WF56
LOCALIZED PROTON DENSITY. RELAXATION TIMES AND SELF DIFFUSION
COEFFICIENT MEASUREMENTS IN SINGLE CELLS BY NMR MICROSCOPY.
J. AEuayo, S. Blackband, J. Schoenlger and M. Mattlngly*, Division
of NMR Research, Johns Hopkins University Medical School, Baltlmore,
Maryland 21205.
l~urDose. To obtain and intrepret localised measurements of proton
density, relaxation times (T1/T2, and self diffusion coefficients of
regions within a single cell.
Methods. A modified Bruker AM 400 spectrometer has been equipped
with imaging software and hardware accessories. Using a 50 mm set
of gradient coils up to 20 G/cm have been generated during imaging
experiments. In order to optimize sensitivity, a 5 mm solenoid were
used for these studies. A spin echo pulse sequence was used to
obtain proton density weighted images. Multi-echo and inversion
recovery programs were used to obtain T 2 and T 1 weighted images
respectively. To obtain self diffusion measurements, the spin echo
and multi-echo programs were modified by adding two pulsed gradients
on either side of the refocusing 180 ° pulse. In these programs a
selective 90 ° pulse was used. Ova were obtained from Xenopus
laevius.
Results. The highest resolution to date has been I0 X 13 X 250
microns (I). A homogeneous cell nucleus and heterogenous cytoplasm
were observed. The highest proton density was in the cell nucleus
followed by the marginal zone (region around the nucleus) and
finally the cytoplasm. The cytoplasm has a high lipid content as
evidenced by a chemically shifted component of the signal from this
region. The cell nuclues was noted to have a long T 1 that was
similar to the T 1 of the surrounding buffer solution and longer than
that of the cytoplasm. The T 2 of the nucleus was longer than that
of the cytoplasm. Diffusion studies are in the process of being
Intrepreted but indicate that the water in the cell nucleus is
similiar to that of free water.
Conclusion. It is now possible to obtain images of single cells and
to obtain localized TI, T2, proton density and self diffusion
measurements from within different regions of single cells. The
properties of the cell nucleus in the cell system that we chose to
study were significantly different than those of the surrounding
cytoplasm. Further study and correlation between these results and
previous observation by other techniques is important in order to
understand the meaning of these observations.
I. Aguayo J.B., Blackband S.J., Schoeniger J.S., Mattingly M.O., and
Hintermann M., Nature, 322, 190-192, 1986.