DePakeing of dipolar chemical-shift NMR spectra

NRC publication: Ye

Ultrasound Induced Increase in Myocardial Contractility: Metabolic Effects Measured by P31 MR Spectroscopy

NRC publication: Ye

High resolution proton NMR detects metastatic potential

Cancerous tissue or a suspension of cultured cancer cells give a high resolution proton NMR spectrum similar to that obtained from lipids. The NMR resonances, which arise from molecules in or attached to the plasma membrane, are consistent with unusually high levels of neutral lipid in the plasma membranes of cancer cells. Two dimensional NMR studies identify triglyceride to be one of the main constituents of these lipid domains. Resolution enhancement techniques applied to either one or two dimensional NMR data allow identification of at least four resonances under the broad methylene peak at 1.2 ppm. The biological status of cancer cells, such as metastatic potential and drug sensitivity profiles, can be identified by the behaviour of one or more of these methylene resonances. A T2 of greater than 600 ms measured for the resonance at 1.25 ppm coincides with the cells ability to metastasise. Those cells which have a T2. of less than 200 ms for this particular resonance have not ‘been found to generate secondary growths

Estimation of the location of natural \u3b1-tocopherol in lipid bilayers by 13C-NMR spectroscopy

Natural, 2R,4\u2032R,8\u2032R-\u3b1-tocopherol (vitamin E), labelled selectively with 13C in the methyl group at position 5, was incorporated into unilamellar vesicles of egg phosphatidylcholine. The vesicles are impermeable to the shift reagent Pr3+ and, in the presence of this reagent, separate 13C resonances due to labelled \u3b1-tocopherol in the outer and inner monolayers could be observed with relative intensities, 2:1. Subsequent addition of the relaxation reagent Gd2+ causes broadening and greatly shortened spin-lattice relaxation times for the resonance due to \u3b1-tocopherol in the outer monolayer only. These data confirm that \u3b1-tocopherol is located in both halves of the bilayers with its more hydrophilic chroman moiety very near the lipid-water interface, and indicate that the methyl group at position 5 of the \u3b1-tocopherol in the inner monolayer must be at least 40 \uc5 from the aqueous interface of the outer monolayer. \ua9 1985.Peer reviewed: YesNRC publication: Ye