scholarly journals Characterization of Cerebral Glutamine Uptake from Blood in the Mouse Brain: Implications for Metabolic Modeling of 13C NMR Data

2014 ◽  
Vol 34 (10) ◽  
pp. 1666-1672 ◽  
Author(s):  
Puneet Bagga ◽  
Kevin L Behar ◽  
Graeme F Mason ◽  
Henk M De Feyter ◽  
Douglas L Rothman ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Metabolic Model ◽  
Synthesis Rate ◽  
Nmr Studies ◽  
Nmr Data ◽  
Glutamine Synthesis ◽  
Time Courses ◽  
Glutamine Uptake ◽  
C Nmr

13C Nuclear Magnetic Resonance (NMR) studies of rodent and human brain using [1-13C]/[1,6-13C2]glucose as labeled substrate have consistently found a lower enrichment (~25% to 30%) of glutamine-C4 compared with glutamate-C4 at isotopic steady state. The source of this isotope dilution has not been established experimentally but may potentially arise either from blood/brain exchange of glutamine or from metabolism of unlabeled substrates in astrocytes, where glutamine synthesis occurs. In this study, the contribution of the former was evaluated ex vivo using 1H-[13C]-NMR spectroscopy together with intravenous infusion of [U-13C5]glutamine for 3, 15, 30, and 60 minutes in mice. 13C labeling of brain glutamine was found to be saturated at plasma glutamine levels > 1.0 mmol/L. Fitting a blood–astrocyte–neuron metabolic model to the 13C enrichment time courses of glutamate and glutamine yielded the value of glutamine influx, VGln(in), 0.036 ± 0.002 μmol/g per minute for plasma glutamine of 1.8 mmol/L. For physiologic plasma glutamine level (~0.6 mmol/L), VGln(in) would be ~0.010 μmol/g per minute, which corresponds to ~6% of the glutamine synthesis rate and rises to ~11% for saturating blood glutamine concentrations. Thus, glutamine influx from blood contributes at most ~20% to the dilution of astroglial glutamine-C4 consistently seen in metabolic studies using [1-13C]glucose.

scholarly journals Glutamatergic and GABAergic TCA Cycle and Neurotransmitter Cycling Fluxes in Different Regions of Mouse Brain

2013 ◽  
Vol 33 (10) ◽  
pp. 1523-1531 ◽  
Author(s):  
Vivek Tiwari ◽  
Susmitha Ambadipudi ◽  
Anant B Patel
Keyword(s):  
Cerebral Cortex ◽  
Mouse Brain ◽  
Ex Vivo ◽  
Tca Cycle ◽  
Metabolic Model ◽  
Nmr Studies ◽  
Inhibitory Function ◽  
The Tca Cycle ◽  
The Brain ◽  
C Nmr

The 13C nuclear magnetic resonance (NMR) studies together with the infusion of 13C-labeled substrates in rats and humans have provided important insight into brain energy metabolism. In the present study, we have extended a three-compartment metabolic model in mouse to investigate glutamatergic and GABAergic tricarboxylic acid (TCA) cycle and neurotransmitter cycle fluxes across different regions of the brain. The 13C turnover of amino acids from [1,6-13C2]glucose was monitored ex vivo using qH-[13C]-NMR spectroscopy. The astroglial glutamate pool size, one of the important parameters of the model, was estimated by a short infusion of [2-13C]acetate. The ratio Vcyc/VTCA was calculated from the steady-state acetate experiment. The 13C turnover curves of [4-13C]/[3-13C]glutamate, [4-13C]glutamine, [2-13C]/[3-13C]GABA, and [3-13C]aspartate from [1,6-13C2]glucose were analyzed using a three-compartment metabolic model to estimate the rates of the TCA cycle and neurotransmitter cycle associated with glutamatergic and GABAergic neurons. The glutamatergic TCA cycle rate was found to be highest in the cerebral cortex (0.91±0.05 μmol/g per minute) and least in the hippocampal region (0.64±0.07 μmol/g per minute) of the mouse brain. In contrast, the GABAergic TCA cycle flux was found to be highest in the thalamus-hypothalamus (0.28±0.01 μmol/g per minute) and least in the cerebral cortex (0.24±0.02 μmol/g per minute). These findings indicate that the energetics of excitatory and inhibitory function is distinct across the mouse brain.

scholarly journals Structural Investigations of C-Nitrosobenzenes. Part 3.1 Solid-state and Solution 13C NMR Studies, and Crystal Structure of E-(4-CIC6H4NO)2

1999 ◽  
Vol 23 (3) ◽  
pp. 202-203
Author(s):  
Daniel A. Fletcher ◽  
Brian G. Gowenlock ◽  
Keith G. Orrell ◽  
David C. Apperley ◽  
Michael B. Hursthouse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Studies ◽  
Structural Investigations ◽  
Nmr Data ◽  
C Nmr

Solid-state and solution 13C NMR data for the monomers and dimers of 3- and 4-substituted nitrosobenzenes, and the crystal structure of E-(4-CIC6H4NO)2 are reported.

Zinc and iron complexes of a helix-directing (1R,2R)-cyclohexyl salen ligand with phenanthryl sidearms

2009 ◽  
Vol 87 (1) ◽  
pp. 224-231 ◽  
Author(s):  
Alexander V Wiznycia ◽  
John Desper ◽  
Christopher J Levy
Keyword(s):  
Metal Complexes ◽  
Iron Complexes ◽  
Single Species ◽  
Nmr Data ◽  
Salen Complexes ◽  
Dft Simulations ◽  
Helical Molecules ◽  
Salen Ligand ◽  
C Nmr

A symmetrical salen ligand is formed by the condensation of (1R,2R)-diaminocyclohexane with 4-hydroxy-3-phenanthrenecarboxaldehyde. Crystallographic characterization of the metal complexes (ZnII, FeII, and FeIII) show 1:1 mixtures of diastereomeric M and P helical molecules. ECD spectra of the ZnII complex combined with DFT simulations strongly suggest that the M conformation is dominant in solution. This is supported by 1H and 13C NMR data, which are consistent with a single species in solution.Key words: zinc, iron, ECD, DFT, salen complexes.

Diehloro(η5 -cyclopentadienyl)chrom-Dimer / Dichloro(η5-cyclopentadienyl)chromium Dimer

1983 ◽  
Vol 38 (11) ◽  
pp. 1406-1411 ◽  
Author(s):  
Frank H. Köhler ◽  
Ren de Cao ◽  
Klaus Ackermann ◽  
Josef Sedlmair
Keyword(s):  
Temperature Dependent ◽  
Nmr Studies ◽  
Magnetic Exchange ◽  
Chlorine Atoms ◽  
X Ray ◽  
Nmr Data ◽  
Metal Metal ◽  
C Nmr

Reaction of chromocene with chloroform yields [Cp2Cr]+[CpCrCl3]- (2) which is trans­formed to trans-[CpCrCl2]2 (3 a) on heating and to a mixture of cis/trans-[CpCrCl2]2 (3 b/a) on standing in chloroform. 2 and 3a/b have been characterized by paramagnetic 1H and 13C NMR yielding the first spectra of the chromocenium cation and the halfsandwich type [CpCrX2L]n-. For comparison, CpCrCl2(pyridine) (4) has been studied; the NMR data of 4 and [CpCrC3]- indicate that both are electronically similar. An X-ray analysis shows one isomer of 3 to be the trans-compound. Its chromium and bridging chlorine atoms consti­tute a square with a metal-metal distance of 336.2 pm. Magnetic exchange is established for 3 a by temperature dependent NMR studies. The X-ray results suggest superexchange to be the dominating mechanism.

Structural determination of the polysaccharide antigens of Neisseria meningitidis serogroups Y, W-135, and BO

1976 ◽  
Vol 54 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Apurba K. Bhattacharjee ◽  
Harold J. Jennings ◽  
C. Paul Kenny ◽  
Adèle Martin ◽  
Ian C. P. Smith
Keyword(s):  
Sialic Acid ◽  
Acetyl Derivative ◽  
Major Product ◽  
Hydroxyl Group ◽  
Nmr Studies ◽  
Acetylneuraminic Acid ◽  
Nmr Data ◽  
Polysaccharide Antigens ◽  
C Nmr

The purified high molecular weight serogoup Y meningococcal polysaccharide contains equimolar proportions of D-glucose and N-acetylneuraminic acid and is partially O-acetylated. Carbon-13 nuclear magnetic resonance (NMR) studies, together with other chemical data, have indicated that the polysaccharide is linked only at C-6 of the D-glucose and C-4 of the sialic acid residues, all the linkages being in the α-configuration. The 13C NMR data also indicated that the Y polysaccharide is composed of an alternating sequence of these two different residues, and this was confirmed by its autohydrolysis where the major product was 4-O-α-D-glucopyranosyl-β-D-N-acetylneuraminic acid. The W-135 polysaccharide differs from that of Y only in the absence of O-acetylation and in the configuration of one hydroxyl group of the disaccharide repeating unit. In this case autohydrolysis yielded 4-O-α-D-galactopyranosyl-β-D-N-acetylneuraminic acid as the major product. Structural evidence indicates that the BO and Y polysaccharides are identical.Methanolysis of the Y polysaccharide yielded in addition to the methyl glycosides of glucose and sialic acid, a 9-O-acetyl derivative of the latter. This derivative was formed during the re-N-acetylation process and its formation was mainly due to the presence of sodium ions in the original polysaccharide.

scholarly journals Combination of capillary GC, GC/MS and13C-NMR for the characterization of the rhizome oil ofPiper betleL. (Piperaceae) from Vietnam

1997 ◽  
Vol 13 (2) ◽  
pp. 131-136 ◽  
Author(s):  
Lê Thanh ◽  
Nguyên Xuân Dung ◽  
Ange Bighelliand ◽  
Joseph Casanova ◽  
Piet A. Leclercq
Keyword(s):  
Essential Oil ◽  
Structure Elucidation ◽  
Mass Spectra ◽  
Piper Betle ◽  
Retention Data ◽  
Capillary Gc ◽  
Nmr Studies ◽  
Identification Techniques ◽  
C Nmr

The essential oil from the rhizomes ofPiper betleL. (betel), collected around Hue, was obtained in 0.20% yield. The oil was examined by a combination of capillary GC and GC/MS.13C-NMR studies confirmed the structure assignments proposed by retention data and mass spectra of the components with a content higher than 1%. In some instances the structure elucidation based on GC and GC/MS data had to be corrected. More than forty constituents were found of which the major ones were α-cadinol (26.2%), δ-cadinene (11.7%), and about equal amounts of T-cadinol and T-muurolol (unseparated, together 20.7%). This study clearly illustrates the advantage of complementary identification techniques.

13C-NMR-Untersuchiingen an einigen Organosilanen /13 C NMR Studies on Some Organosilanes

1979 ◽  
Vol 34 (9) ◽  
pp. 1270-1274 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Werner Biffar
Keyword(s):  
13C Nmr ◽  
Structural Features ◽  
Coupling Constants ◽  
Coupling Mechanism ◽  
Nmr Studies ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Fermi Contact ◽  
Fermi Contact Term ◽  
C Nmr

Abstract13C-NMR data (δ13C, J(13C1H), J(13C13C), J(29Si13C)) of noncyclic organosilanes CH4-n[Si(CH3)3]n (n = 1-4), (CH3)4-nC[Si(CH3)3]n (n = 1, 3, 4) and cyclic organosilanes [(CH3)2SiCH2]n (n = 2, 3), (CH3)2Si(CH2)3 are reported. Comparison of reduced coupling constants 1K proves the Fermi-contact-term to be the dominant coupling mechanism. Structural features of the four-membered heterocycles become apparent by comparison of their 13C NMR parameters with those of corresponding cycloalkanes, noncyclic organo­silanes and the 1,3,5-trisilacyclohexane derivative.

Darstellung und Strukturelle Charakterisierung von cis-und trans- Dicyclohexyl-3,3′,4,4′-tetracarbonsäure-tetramethylestern / Preparation and Structural Characterization of cis- and trans-Tetramethyl Dicyclohexyl-3,3′,4,4′-tetracarboxylates

2001 ◽  
Vol 56 (2) ◽  
pp. 189-201
Author(s):  
Akinori Shiotani
Keyword(s):  
Catalytic Hydrogenation ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Trans Isomers ◽  
X Ray ◽  
Nmr Data ◽  
Methoxycarbonyl Group ◽  
Cis And Trans ◽  
C Nmr

Abstract In the catalytic hydrogenation of tetramethyl biphenyl-3,3′,4,4′-tetracarboxylate, tetramethyl dicyclohexyl-3,3′,4,4′-tetracarboxylates were obtained, from which we have isolated cis isomers as crystals. The base-catalyzed isomerization afforded the trans isomers. The structure of the products isolated was determined by single-crystal x-ray diffraction, which clearly reveals the axial and equatorial positions of the methoxycarbonyl group. The structures in solution are supported by 1H and 13C NMR data, and also by two-dimensional COSY techniques.

Sesquiterpenes and Flavonoid Aglycones from a Hungarian Taxon of the Achillea millefolium Group

2002 ◽  
Vol 57 (11-12) ◽  
pp. 976-982 ◽  
Author(s):  
Sabine Glasl ◽  
Pavel Mucaji ◽  
Ingrid Werner ◽  
Armin Presser ◽  
Johann Jurenitsch
Keyword(s):  
2D Nmr ◽  
The Other ◽  
Achillea Millefolium ◽  
Spectroscopic Methods ◽  
Nmr Studies ◽  
Flavonoid Aglycones ◽  
H Nmr ◽  
Nmr Data ◽  
First Time ◽  
C Nmr

The investigation of a dichloromethane extract of flower heads of a Hungarian taxon of the Achillea millefolium group led to the isolation of three flavonoid aglycones, one triterpene, one germacranolide and five guaianolides. Their structures were elucidated by UV-VIS, EI- and CI-MS, 1H NMR and 13C NMR spectroscopic methods as well as by 2D-NMR studies and by selective 1D-NOE experiments. Besides apigenin, luteolin and centaureidin, β-sitosterol, 3β-hydroxy-11α,13-dihydro-costunolide, desacetylmatricarin, leucodin, achillin, 8α-angeloxy-leucodin and 8α-angeloxy-achillin were isolated. Both latter substances are reported here for the first time. Their NMR data were compared with those of the other guaianolides. The stereochemistry of 3β-hydroxy-11α,13-dihydro-costunolide was discussed and compared with data of the literature.

Carbon-carbon coupling of 4,6-dinitrobenzofuroxan with 3-aminothiophenes: a kinetic and structural study

1998 ◽  
Vol 76 (6) ◽  
pp. 937-945 ◽  
Author(s):  
François Terrier ◽  
Marie-José Pouet ◽  
Khalid Gzouli ◽  
Jean-Claude Hallé ◽  
Francis Outurquin ◽  
...  
Keyword(s):  
Negative Charge ◽  
Dilute Acid ◽  
Amino Groups ◽  
Nmr Studies ◽  
Carbon Nucleophiles ◽  
Nmr Data ◽  
Potentiometric Measurements ◽  
Nucleophilic Reactivity ◽  
Negative Charge Density ◽  
C Nmr

Potentiometric measurements carried out in a 50-50 (v/v) H2O-Me2SO mixture together with 1H and 13C NMR studies carried out in pure Me2SO-d6 reveal that 3-aminothiophene (4a), 3-N-(methylamino)thiophene (4b), and 3-N,N-dimethylaminothiophene (4c) undergo protonation exclusively at the amino groups in dilute acid solutions. The pKa values of 4a, 4b, and 4c are equal to 3.38, 3.65, and 3.53, respectively, at 25°C, comparing well with those for related anilines in the same aqueous Me2SO mixtures. However, despite this similarity of the nitrogen basicities, compounds 4a, 4b, and 4c are found to behave differently from anilines upon treatment with super-electrophilic 4,6-dinitrobenzofuroxan (DNBF). While anilines react to give first an N-bonded sigma -adduct that subsequently decomposes to afford the thermodynamically more stable C-bonded adduct, the 3-aminothiophenes react only as carbon nucleophiles, giving rise directly to the corresponding C-adducts. Based on 1H and 13C NMR data as well as measurements of the rate constants (k1DNBF) for DNBF addition to 4a, 4b, and 4c, it is demonstrated that 3-aminothiophenes possess such high negative charge density at C-2 that they can be regarded as strongly enaminic in nature. Estimates of the pKa values for protonation at C-2 of 4a, 4b, and 4c could be made: pKa4a approx -0.4; pKa4b approx 0.2; pKa4c approx 0.8. Thus, these compounds are more susceptible to electrophilic addition at this position than most of the five-membered ring heterocycles studied so far. Altogether, the results demonstrate the importance of the hyper-ortho relationship in the thiophene systems, accounting for the ease of both electrophilic and nucleophilic reactivity of 3-X-thiophenes in σ -complex formation processes.Key words: aminothiophenes, enamines, superelectrophiles, dinitrobenzofuroxan, hyper-ortho relationship.

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