NMR Applications
NMR can be a very versatile tool in elucidating structure, dynamics, and composition of a wide range of materials. Occasionally, our group approaches or is approached by other research groups to help solve a particular problem using NMR. The Walls group is always welcoming of collaborations that could benefit from NMR (either with existing methodologies or ones that need to be developed to address the problem).
Metabolomics refers to the quantifying metabolites in biological systems. NMR can be used to routinely identify between 30-100 metabolites that are present in biological samples. In collaboration with Dr. Priyamvada Rai in the Department of Medicine at the University of Miami's Miller School of Medicine, we used NMR metabolomics to answer the following question: the RAS oncogene has three common isoforms, HRAS, KRAS, and NRAS. What significant metabolomic differences can be observed between an isogenic control (BEAS2B cells) and oncogenic HRAS-, KRAS-, and NRAS-transduced BEAS2B cells (western blot confirming successful transduction is shown in top left)? Metabolites were extracted from the cell cultures and NMR experiments were performed on each sample, with typical results given on the bottom figure (the water resonance was not shown for simplicity). The metabolites were identified and quantified using CHENOMIX software, and analyzed using a battery of statistical methods. In the upper right, a plot of the observed lactate concentrations (relative to glutamate) vs. the observed phosphocholine concentrations (relative to glutamate) are shown, with 99% confidence ellipses drawn. As can be seen, all four cell lines show distinct signatures. The Walls group has also collaborated with Dr. Danny Yakoub in the Department of Surgery at the University of Miami, Miller School of Medicine on studying GIST treatment with Imatinib.
Measuring Drug Release Kinetics in Emulsions
Our group has worked in collaboration with Dr. Christopher A. Fraker at the Diabetes Research Institute at the Miller School of Medicine at the University of Miami to determine the in vivo release kinetics of a poorly water-soluble drug, isoflurane, from an injectable anesthetic composed of an emulsified solution of isoflurane in perfluorotributylamine. Using NMR exchange theory and a local compositional model, we found that the release times of isoflurane from the emulsion were almost seven orders of magnitude faster than those determined from conventional reverse-dialysis measurements.
