NMR relaxation of protons in tissues and other macromolecular water solutions

Fullerton, Gary D.; Potter, Janet L.; Dornbluth, Nella Carol

doi:10.1016/0730-725x(82)90172-2

Cited by 210 publications

(109 citation statements)

References 21 publications

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“…In our experiment of PTP opening, the continuous decrease in t D observed from 10 mM Ca 2 þ can be explained by a reduction of the packing arrangement in space which is responsible for a progressive increase of the exchange rate between water molecules localized in different layers/molecular environments within the hydration shell of macromolecules in the matrix. 26 Comparison of the temperature dependency of the amount of structured water demonstrates that the significant increase induced by 100 mM Ca 2 þ and over is much more at 255 than at 240 K.…”

Section: Discussionmentioning

confidence: 99%

Mitochondrial membrane permeabilization produced by PTP, Bax and apoptosis: a 1H-NMR relaxation study

et al. 2005

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To analyze the involvement of structured water (bound to macromolecules) in apoptosis-induced mitochondrial outermembrane permeability, we compared the dynamics of water protons from nuclear magnetic resonance (NMR) data in apoptotic liver mitochondria with that of control mitochondria incubated in vitro with free Ca 2 þ (opening of the permeability transition pore, PTP) or with Bax a. Our results demonstrate that water molecules in apoptotic mitochondria exhibit an accelerated translational motion of structured water common with that induced by the opening of the PTP, but limited in amplitude. On the other hand, no significant quantitative change in structured water was observed in apoptotic mitochondria, a phenomenon also observed with Bax ainduced permeability. We conclude that the changes observed in the different water phases differ both quantitatively and qualitatively during the opening of the PTP and the Bax a-induced permeability, and that the apoptotic mitochondria exhibit mixed properties between these model situations.

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Section: Discussionmentioning

confidence: 99%

Mitochondrial membrane permeabilization produced by PTP, Bax and apoptosis: a 1H-NMR relaxation study

et al. 2005

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“…Other researchers have observed increasing Ti values with increasing water content and a greater proportion of free water (which would increase Ti values) (14). The measured values of Ti are determined as the reciprocal of the summation of the proton components (primarily water in plant studies) ofthe material under study and can be determined by 1/Ti = (1/Ti1) + (1/Ti2) + (1/Ti3) + .…”

Section: Resultsmentioning

confidence: 99%

Observation of a water-depletion region surrounding loblolly pine roots by magnetic resonance imaging.

MacFall

Johnson

Kramer

1990

Proc. Natl. Acad. Sci. U.S.A.

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Magnetic resonance imaging was used to study sand containing various amounts of water and roots of loblolly pine planted into similar sand. Spin-lattice (Ti) relaxation times of sand with water contents ranging from 0 to 25% (wt/wt) ranged from 472 to 1265 ms and increased with water content. Spin-spin (T2) relaxation times ranged from 54 to 76 ms and did not change in a discernible pattern with water content. Based on water content and measured Ti and 72 values, the signal intensity ofsand/water images was predicted to increase with water content in a linear fashion, with the slope of the lines increasing with the time of acquisition repetition (TR). Measured signal intensity from images of sand with various water contents was found to follow a similar pattern.

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“…This bias can arise because of components that have not been explicitly included in the model. However, it has previously been shown that macromolecular and iron components, which are rather well captured by MT and R 2 * respectively,31, 32 are the dominant contributors to R 1 11, 15, 16, 33, 34, 35. Any orientation‐dependent or higher‐order relationships that exist between the qMRI maps are not captured by the model either, and may also be a source of bias 36…”

Section: Discussionmentioning

confidence: 99%

Synthetic quantitative MRI through relaxometry modelling

2016

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Quantitative MRI (qMRI) provides standardized measures of specific physical parameters that are sensitive to the underlying tissue microstructure and are a first step towards achieving maps of biologically relevant metrics through in vivo histology using MRI. Recently proposed models have described the interdependence of qMRI parameters. Combining such models with the concept of image synthesis points towards a novel approach to synthetic qMRI, in which maps of fundamentally different physical properties are constructed through the use of biophysical models. In this study, the utility of synthetic qMRI is investigated within the context of a recently proposed linear relaxometry model. Two neuroimaging applications are considered. In the first, artefact‐free quantitative maps are synthesized from motion‐corrupted data by exploiting the over‐determined nature of the relaxometry model and the fact that the artefact is inconsistent across the data. In the second application, a map of magnetization transfer (MT) saturation is synthesized without the need to acquire an MT‐weighted volume, which directly leads to a reduction in the specific absorption rate of the acquisition. This feature would be particularly important for ultra‐high field applications. The synthetic MT map is shown to provide improved segmentation of deep grey matter structures, relative to segmentation using T 1‐weighted images or R 1 maps. The proposed approach of synthetic qMRI shows promise for maximizing the extraction of high quality information related to tissue microstructure from qMRI protocols and furthering our understanding of the interrelation of these qMRI parameters.

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NMR relaxation of protons in tissues and other macromolecular water solutions

Cited by 210 publications

References 21 publications

Mitochondrial membrane permeabilization produced by PTP, Bax and apoptosis: a 1H-NMR relaxation study

Mitochondrial membrane permeabilization produced by PTP, Bax and apoptosis: a 1H-NMR relaxation study

Observation of a water-depletion region surrounding loblolly pine roots by magnetic resonance imaging.

Synthetic quantitative MRI through relaxometry modelling

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