Robin A de Graaf15
Graeme F Mason14
Anant B Patel12
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To determine whether plasma lactate can be a significant fuel for human brain energy metabolism, infusions of [3-(13)C]lactate and (1)H-(13)C polarization transfer spectroscopy were used to detect the entry and utilization of lactate. During the 2 h infusion study, (13)C incorporation in the amino acid pools of glutamate and glutamine were measured with a 5(More)
Prior 13C magnetic resonance spectroscopy (MRS) experiments, which simultaneously measured in vivo rates of total glutamate-glutamine cycling (V(cyc(tot))) and neuronal glucose oxidation (CMR(glc(ox), N)), revealed a linear relationship between these fluxes above isoelectricity, with a slope of approximately 1. In vitro glial culture studies examining(More)
Functional MRI (fMRI) is widely assumed to measure neuronal activity, but no satisfactory mechanism for this linkage has been identified. Here we derived the changes in the energetic component from the blood oxygenation level-dependent (BOLD) fMRI signal and related it to changes in the neuronal spiking frequency in the activated voxels. Extracellular(More)
Previous studies have shown that the glutamate/glutamine (Glu/Gln) neurotransmitter cycle and neuronal glucose oxidation are proportional (1:1), with increasing neuronal activity above isoelectricity. GABA, a product of Glu metabolism, is synthesized from astroglial Gln and contributes to total Glu/Gln neurotransmitter cycling, although the fraction(More)
13C NMR spectroscopy in combination with the infusion of (13)C-labeled precursors is currently the only technique that is capable of quantitatively studying energy metabolism, neurotransmission and other metabolic pathways non-invasively in vivo. (1)H-[(13)C]-NMR spectroscopy is a high-sensitivity alternative to direct (13)C NMR spectroscopy. The(More)
The complex activities of the brain need not distract us from the certainty that it uses energy and performs work very efficiently. The human brain, which claims approximately 2% of our body mass, is responsible for approximately 20% of our body oxygen consumption. In vivo magnetic resonance spectroscopy (MRS) follows the metabolic pathways of energy(More)
Until very recently, non-invasive measurement of the glutamate-glutamine cycle in the intact mammalian brain had not been possible. In this review, we describe some studies that have led to quantitative assessment of the glutamate-glutamine cycle (Vcyc), as well as other important metabolic fluxes (e.g., glucose oxidation, CMRglc(ox)), with (13)C magnetic(More)
Comprehensive and quantitative measurements of T1 and T2 relaxation times of water, metabolites, and macromolecules in rat brain under similar experimental conditions at three high magnetic field strengths (4.0 T, 9.4 T, and 11.7 T) are presented. Water relaxation showed a highly significant increase (T1) and decrease (T2) with increasing field strength for(More)
A decline in brain function is a characteristic feature of healthy aging; however, little is known about the biologic basis of this phenomenon. To determine whether there are alterations in brain mitochondrial metabolism associated with healthy aging, we combined (13)C/(1)H magnetic resonance spectroscopy with infusions of [1-(13)C]glucose and(More)
Multivolume (1)H-[(13)C] NMR spectroscopy in combination with i.v. [1,6-(13)C(2)]glucose infusion was used to detect regional glucose metabolism and glutamatergic neurotransmission in the halothane-anesthetized rat brain at 7 T. The regional information was decomposed into pure cerebral gray matter, white matter, and subcortical structures by means of(More)