The T1 and T2 NMR relaxation times of water protons in plasma, obtained from patients with lung carcinoma, healthy volunteers, and patients with nontumor diseases were measured at a resonance frequency of 20 MHz. Additionally hematologic parameters were determined. In tumor patients the mean plasma
Interactions of nitroxides with plasma and blood: Effect on 1/T1 of water protons
✍ Scribed by Harold F. Bennett; Rodney D. Brown; John F. W. Keana; Seymour H. Koenig; Harold M. Swartz
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 893 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0740-3194
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Nitroxide stable free radicals (nitroxides) have potential utility as MRI contrast‐enhancing agents with the additional capability of reflecting redox metabolism. In order to gain a better understanding of their potential interactions in vivo, we have studied the longitudinal NMRD profiles (1 / T~1~ as a function of field strength) and ESR spectra for lipophilic and aqueous‐soluble nitroxides in blood, plasma, and plasma components. Typical water‐soluble nitroxides do not interact appreciably with blood, plasma, or plasma proteins. Fatty acid nitroxides do interact physically with blood, predominantly by intercalation within red blood cell membranes and binding to albumin. The latter interaction results in significantly enhanced relaxivity for the nitroxide/HSA complex. Relaxation of water protons in this case is dominated by inner sphere processes, ostensibly due to water molecules hydrogen bonded to nitroxide moieties. The rotational reorientation time for the complex, the electronic relaxation time, and the exchange time for the water molecule reversably bound to the nitroxide, all appear significantly to influence the correlation time (∼ 16 ns) for this inner sphere contribution. Inc. © 1990 Academic Press, Inc.
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