Studying enzymes by in vivo 13C magnetic resonance spectroscopy

Xu, Su; Shen, Jun

doi:10.1016/j.pnmrs.2009.06.002

Cited by 5 publications

(4 citation statements)

References 167 publications

(194 reference statements)

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“…3). Because the in vivo 13 C saturation (or inversion) transfer effect of enzyme‐catalyzed reactions can be used to measure enzyme‐specific reactions in vivo 31–33, 50, the negative saturation transfer results obtained here are consistent with previous studies that found minimal ADH, CYP2E1 and Cata activities in brain tissue. In comparison, a large 13 C saturation transfer effect caused by the exchange between ethanol and acetaldehyde is easily observable using rat liver homogenate (data not shown).…”

Section: Discussionsupporting

confidence: 90%

In vivo detection of intermediate metabolic products of [1‐¹³C]ethanol in the brain using ¹³C MRS

Xiang

Shen

2011

NMR in Biomedicine

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In the present study, in vivo 13C magnetic resonance spectroscopy (MRS) was used to study the labeling of brain metabolites after intravenous administration of [1-13C]ethanol. After [1-13C]ethanol was systemically administrated to the rats, 13C labels were detected in glutamate, glutamine and aspartate in the carboxylic and amide carbon spectral region. 13C-labeled bicarbonate HCO3− (161.0 ppm) was also detected. Saturating acetaldehyde C1 at 207.0 ppm was found to have no effect on the ethanol C1 (57.7 ppm) signal intensity after extensive signal averaging, providing direct in vivo evidence that direct metabolism of alcohol by brain tissue is minimal. To compare the labeling of brain metabolites by ethanol with labeling by glucose, in vivo time course data were acquired during intravenous co-infusion of [1-13C]ethanol and [13C6]-D-glucose. In contrast to labeling by [13C6]-D-glucose which produced doublets of carboxylic/amide carbons with a J coupling constant of 51 Hz, the simultaneously detected glutamate and glutamine singlets are labeled by [1-13C]ethanol. Since 13C labels originated from ethanol enter brain after being converted into [1-13C]acetate in liver and the direct metabolism of ethanol by brain tissue is negligible, it is suggested that orally or intragastrically administered 13C-labeled ethanol may be used to study brain metabolism and glutamatergic neurotransmission in studies involving alcohol administration. In vivo 13C MRS of rat brain following intragastric administration of 13C-labeled ethanol is demonstrated.

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Section: Discussionsupporting

confidence: 90%

In vivo detection of intermediate metabolic products of [1‐¹³C]ethanol in the brain using ¹³C MRS

Xiang

Shen

2011

NMR in Biomedicine

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“…From and Ugurbil do an excellent job of describing this approach of measuring unidirectional reaction rates. The most studied reaction in tissues has been creatine kinase, but there are a growing number of enzymes that can be studied by NMRS magnetization transfer techniques (41).…”

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confidence: 99%

“…These data demonstrate that the amplification of the saturation transfer experiment for detecting metabolites is remarkable. Recently, a number of enzymes have been detected using the idea to saturate where a small metabolite pool is located (41). Indeed, specific contrast agents based on exchange amplification (chemical exchange-dependent saturation transfer agents; CEST) are under active development (17,38).…”

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confidence: 99%

Interpretation of³¹P NMR saturation transfer experiments: what you can't see might confuse you. Focus on “Standard magnetic resonance-based measurements of the P_i→ATP rate do not index the rate of oxidative phosphorylation in cardiac and skeletal muscles”

Balaban

Koretsky

2011

American Journal of Physiology-Cell Physiology

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“…It has provided rates for specific metabolic routes, such as neurotransmitter cycling (Glu/glutamine) [35], allowed to establish the energy cost of brain function, and provided various other highly important information (reviewed in Ref [39]). Recently, 13C-MRS also provided exchange rates for individual enzymes [40], using saturation transfer.…”

Section: Carbon-based Brain Spectroscopymentioning

confidence: 99%

Prospects and limitations of algorithmic cooling

et al. 2014

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Heat-bath algorithmic cooling (AC) of spins is a theoretically powerful effective cooling approach, that (ideally) cools spins with low polarization exponentially better than cooling by reversible entropy manipulations alone. Here, we investigate the limitations and prospects of AC. For non-ideal and semioptimal AC, we study the impact of finite relaxation times of reset and computation spins on the achievable effective cooling. We derive, via simulations, the attainable cooling levels for given ratios of relaxation times using two semioptimal practicable algorithms. We expect this analysis to be valuable for the planning of future experiments. For ideal and optimal AC, we make use of lower bounds on the number of required reset steps, based on entropy considerations, to present important consequences of using AC as a tool for improving signal-to-noise ratio in liquid-state magnetic resonance spectroscopy. We discuss the potential use of AC for noninvasive clinical diagnosis and drug monitoring, where it may have significantly lower specific absorption rate (SAR) with respect to currently used methods.

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Studying enzymes by in vivo 13C magnetic resonance spectroscopy

Cited by 5 publications

References 167 publications

In vivo detection of intermediate metabolic products of [1‐¹³C]ethanol in the brain using ¹³C MRS

In vivo detection of intermediate metabolic products of [1‐¹³C]ethanol in the brain using ¹³C MRS

Interpretation of³¹P NMR saturation transfer experiments: what you can't see might confuse you. Focus on “Standard magnetic resonance-based measurements of the P_i→ATP rate do not index the rate of oxidative phosphorylation in cardiac and skeletal muscles”

Prospects and limitations of algorithmic cooling

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Studying enzymes by in vivo 13C magnetic resonance spectroscopy

Cited by 5 publications

References 167 publications

In vivo detection of intermediate metabolic products of [1‐13C]ethanol in the brain using 13C MRS

In vivo detection of intermediate metabolic products of [1‐13C]ethanol in the brain using 13C MRS

Interpretation of31P NMR saturation transfer experiments: what you can't see might confuse you. Focus on “Standard magnetic resonance-based measurements of the Pi→ATP rate do not index the rate of oxidative phosphorylation in cardiac and skeletal muscles”

Prospects and limitations of algorithmic cooling

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In vivo detection of intermediate metabolic products of [1‐¹³C]ethanol in the brain using ¹³C MRS

In vivo detection of intermediate metabolic products of [1‐¹³C]ethanol in the brain using ¹³C MRS

Interpretation of³¹P NMR saturation transfer experiments: what you can't see might confuse you. Focus on “Standard magnetic resonance-based measurements of the P_i→ATP rate do not index the rate of oxidative phosphorylation in cardiac and skeletal muscles”