The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Craig R Malloy - One of the best experts on this subject based on the ideXlab platform.
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the ratio of acetate to glucose oxidation in astrocytes from a single 13c NMR Spectrum of cerebral cortex
Journal of Neurochemistry, 2015Co-Authors: Isaac Marinvalencia, Kumar Pichumani, Dean A Sherry, Ali M Hooshyar, Craig R MalloyAbstract:The (13) C-labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of (13) C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single (13) C NMR Spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-(13) C]acetate and [1,6-(13) C]glucose, and proton decoupled (13) C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that (13) C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. As this method relies on a single (13) C NMR Spectrum, it can be readily applied to multiple physiologic and pathologic conditions. Differences in (13) C labeling of brain glutamate and glutamine have been attributed to metabolic compartmentation. The acetate:glucose ratio, introduced for description of a (13) C NMR (nuclear magnetic resonance) Spectrum, is an index of glucose and acetate oxidation in brain tissue. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes from a single NMR Spectrum. As kinetic analysis is not required, the method is readily applicable to analysis of tissue extracts. α-KG = alpha-ketoglutarate; CAC = citric acid cycle; GLN = glutamine; GLU = glutamate.
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The ratio of acetate‐to‐glucose oxidation in astrocytes from a single 13C NMR Spectrum of cerebral cortex
Journal of neurochemistry, 2014Co-Authors: Isaac Marin-valencia, M. Ali Hooshyar, Kumar Pichumani, A. Dean Sherry, Craig R MalloyAbstract:The (13) C-labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of (13) C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single (13) C NMR Spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-(13) C]acetate and [1,6-(13) C]glucose, and proton decoupled (13) C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that (13) C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. As this method relies on a single (13) C NMR Spectrum, it can be readily applied to multiple physiologic and pathologic conditions. Differences in (13) C labeling of brain glutamate and glutamine have been attributed to metabolic compartmentation. The acetate:glucose ratio, introduced for description of a (13) C NMR (nuclear magnetic resonance) Spectrum, is an index of glucose and acetate oxidation in brain tissue. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes from a single NMR Spectrum. As kinetic analysis is not required, the method is readily applicable to analysis of tissue extracts. α-KG = alpha-ketoglutarate; CAC = citric acid cycle; GLN = glutamine; GLU = glutamate.
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dipolar cross relaxation modulates signal amplitudes in the 1h NMR Spectrum of hyperpolarized 13c formate
Journal of Magnetic Resonance, 2007Co-Authors: Matthew E Merritt, Crystal Harrison, William Mander, Craig R Malloy, Dean A SherryAbstract:Abstract The asymmetry in the doublet of a spin coupled to hyperpolarized 13 C has been used previously to measure the initial polarization of 13 C. We tested the hypothesis that a single observation of the 1 H NMR Spectrum of hyperpolarized 13 C formate monitors 13 C polarization. Depending on the microwave frequency during the polarization process, in-phase or out-of-phase doublets were observed in the 1 H NMR Spectrum. Even in this simple two-spin system, 13 C polarization was not reflected in the relative area of the J CH doublet components due to strong heteronuclear cross-relaxation. The Solomon equations were used to model the proton signal as a function of time after polarization and to estimate 13 C polarization from the 1 H NMR spectra.
Dean A Sherry - One of the best experts on this subject based on the ideXlab platform.
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the ratio of acetate to glucose oxidation in astrocytes from a single 13c NMR Spectrum of cerebral cortex
Journal of Neurochemistry, 2015Co-Authors: Isaac Marinvalencia, Kumar Pichumani, Dean A Sherry, Ali M Hooshyar, Craig R MalloyAbstract:The (13) C-labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of (13) C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single (13) C NMR Spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-(13) C]acetate and [1,6-(13) C]glucose, and proton decoupled (13) C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that (13) C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. As this method relies on a single (13) C NMR Spectrum, it can be readily applied to multiple physiologic and pathologic conditions. Differences in (13) C labeling of brain glutamate and glutamine have been attributed to metabolic compartmentation. The acetate:glucose ratio, introduced for description of a (13) C NMR (nuclear magnetic resonance) Spectrum, is an index of glucose and acetate oxidation in brain tissue. A simple mathematical method is presented to quantify the ratio of acetate-to-glucose oxidation in astrocytes from a single NMR Spectrum. As kinetic analysis is not required, the method is readily applicable to analysis of tissue extracts. α-KG = alpha-ketoglutarate; CAC = citric acid cycle; GLN = glutamine; GLU = glutamate.
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dipolar cross relaxation modulates signal amplitudes in the 1h NMR Spectrum of hyperpolarized 13c formate
Journal of Magnetic Resonance, 2007Co-Authors: Matthew E Merritt, Crystal Harrison, William Mander, Craig R Malloy, Dean A SherryAbstract:Abstract The asymmetry in the doublet of a spin coupled to hyperpolarized 13 C has been used previously to measure the initial polarization of 13 C. We tested the hypothesis that a single observation of the 1 H NMR Spectrum of hyperpolarized 13 C formate monitors 13 C polarization. Depending on the microwave frequency during the polarization process, in-phase or out-of-phase doublets were observed in the 1 H NMR Spectrum. Even in this simple two-spin system, 13 C polarization was not reflected in the relative area of the J CH doublet components due to strong heteronuclear cross-relaxation. The Solomon equations were used to model the proton signal as a function of time after polarization and to estimate 13 C polarization from the 1 H NMR spectra.
Malcolm H. Levitt - One of the best experts on this subject based on the ideXlab platform.
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Fine structure in the solution state 13C-NMR Spectrum of C60 and its endofullerene derivatives
Physical chemistry chemical physics : PCCP, 2020Co-Authors: George R. Bacanu, Gabriela Hoffman, Michael Amponsah, Maria Concistrè, Richard J. Whitby, Malcolm H. LevittAbstract:The 13C NMR Spectrum of fullerene C60 in solution displays two small “side peaks” on the shielding side of the main 13C peak, with integrated intensities of 1.63% and 0.81% of the main peak. The two side peaks are shifted by −12.6 ppb and −20.0 ppb with respect to the main peak. The side peaks are also observed in the 13C NMR spectra of endofullerenes, but with slightly different shifts relative to the main peak. We ascribe the small additional peaks to minor isotopomers of C60 containing two adjacent 13C nuclei. The shifts of the additional peaks are due to a secondary isotope shift of the 13C resonance caused by the substitution of a 12C neighbour by 13C. Two peaks are observed since the C60 structure contains two different classes of carbon–carbon bonds with different vibrational characteristics. The 2 : 1 ratio of the side peak intensities is consistent with the known structure of C60. The origin and intensities of the 13C side peaks are discussed, together with an analysis of the 13C solution NMR Spectrum of a 13C-enriched sample of C60, which displays a relatively broad 13C NMR peak due to a statistical distribution of 13C isotopes. The Spectrum of 13C-enriched C60 is analyzed by a Monte Carlo simulation technique, using a theorem for the second moment of the NMR Spectrum generated by J-coupled spin clusters.
Jari Forsström - One of the best experts on this subject based on the ideXlab platform.
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A PC program for automatic analysis of NMR Spectrum series
Computer Methods and Programs in Biomedicine, 1997Co-Authors: Jaakko Järvi, Samuel Nyman, Markku Komu, Jari ForsströmAbstract:31P nuclear magnetic resonance (NMR) spectroscopy enables us to study intracellular energy metabolism noninvasively. The present work concerns the analysis of a series of 31P NMR spectra on human muscle during exercise. The spectra contain signals corresponding to certain metabolites in the sample and the aim is to identify and quantify these signals. We have written a PC program to perform this task automatically. With the program the results can be achieved substantially faster compared to operating with the spectrometer software. The methods implemented in the program and the functions of the program itself are described. Although we have focused on the 31P NMR Spectrum series, the program can also be applied to other liquid state NMR spectra.
Crystal Harrison - One of the best experts on this subject based on the ideXlab platform.
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dipolar cross relaxation modulates signal amplitudes in the 1h NMR Spectrum of hyperpolarized 13c formate
Journal of Magnetic Resonance, 2007Co-Authors: Matthew E Merritt, Crystal Harrison, William Mander, Craig R Malloy, Dean A SherryAbstract:Abstract The asymmetry in the doublet of a spin coupled to hyperpolarized 13 C has been used previously to measure the initial polarization of 13 C. We tested the hypothesis that a single observation of the 1 H NMR Spectrum of hyperpolarized 13 C formate monitors 13 C polarization. Depending on the microwave frequency during the polarization process, in-phase or out-of-phase doublets were observed in the 1 H NMR Spectrum. Even in this simple two-spin system, 13 C polarization was not reflected in the relative area of the J CH doublet components due to strong heteronuclear cross-relaxation. The Solomon equations were used to model the proton signal as a function of time after polarization and to estimate 13 C polarization from the 1 H NMR spectra.
