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Quantitative assessment of cerebral glucose consumption rate (CMRglc) and tricarboxylic acid cycle flux (VTCA) is crucial for understanding neuroenergetics under physiopathological conditions. In this study, we report a novel in vivo Deuterium (2H) MRS (DMRS) approach for simultaneously measuring and quantifying CMRglc and VTCA in rat brains at 16.4 Tesla. Following a brief infusion of deuterated glucose, dynamic changes of isotope-labeled glucose, glutamate/glutamine (Glx) and water contents in the brain can be robustly monitored from their well-resolved 2H resonances. Dynamic DMRS glucose and Glx data were employed to determine CMRglc and VTCA concurrently. To test the sensitivity of this method in response to altered glucose metabolism, two brain conditions with different anesthetics were investigated. Increased CMRglc (0.46 vs. 0.28 µmol/g/min) and VTCA (0.96 vs. 0.6 µmol/g/min) were found in rats under morphine as compared to deeper anesthesia using 2% isoflurane. This study demonstrates the feasibility and new utility of the in vivo DMRS approach to assess cerebral glucose metabolic rates at high/ultrahigh field. It provides an alternative MRS tool for in vivo study of metabolic coupling relationship between aerobic and anaerobic glucose metabolisms in brain under physiopathological states.

The application of (17)O MRI and MRS for the evaluation of cardiac mitochondrial function has been limited because of the challenge of detecting metabolic H(2)(17)O in the vast background of naturally abundant H(2)(17)O. In this study, we have developed a direct (17)O MRS approach to examine the feasibility and sensitivity of detecting metabolically produced H(2)(17)O in isolated rat hearts perfused with (17)O(2)-enriched Krebs-Henseleit buffer containing normal (1.5 mm) and high (2.5 mm) calcium (Ca(2+)) concentrations to induce high workload. Consistent with increased workload at high Ca(2+) concentration, the measured myocardial oxygen consumption rate (MVO(2)) increased by 82%. Dynamic (17)O MRS showed an accelerated increase in the H(2)(17)O signal at high Ca(2+) concentration, suggesting increased mitochondrial production of H(2)(17)O in concordance with the increased workload. A compartment model was developed to describe the kinetics of H(2)(17)O production as a function of MVO(2). The myocardial (17)O(2) consumption rate (MV(17)O(2) was determined by least-squares fitting of the model to the NMR-measured H(2)(17)O concentration. Consistent with the measured MVO(2), the model-determined MV(17)O(2) showed a 92% increase at high Ca(2+) concentration. The increase in metabolic activity at high workload allowed the balance between ATP production and utilization to be maintained, leading to a similar phosphocreatine to ATP ratio. These results demonstrate that dynamic (17)O MRS can provide a valuable tool for the detection of an altered metabolic rate associated with a change in cardiac workload.

The application of (17)O MRI and MRS for the evaluation of cardiac mitochondrial function has been limited because of the challenge of detecting metabolic H(2)(17)O in the vast background of naturally abundant H(2)(17)O. In this study, we have developed a direct (17)O MRS approach to examine the feasibility and sensitivity of detecting metabolically produced H(2)(17)O in isolated rat hearts perfused with (17)O(2)-enriched Krebs-Henseleit buffer containing normal (1.5 mm) and high (2.5 mm) calcium (Ca(2+)) concentrations to induce high workload. Consistent with increased workload at high Ca(2+) concentration, the measured myocardial oxygen consumption rate (MVO(2)) increased by 82%. Dynamic (17)O MRS showed an accelerated increase in the H(2)(17)O signal at high Ca(2+) concentration, suggesting increased mitochondrial production of H(2)(17)O in concordance with the increased workload. A compartment model was developed to describe the kinetics of H(2)(17)O production as a function of MVO(2). The myocardial (17)O(2) consumption rate (MV(17)O(2) was determined by least-squares fitting of the model to the NMR-measured H(2)(17)O concentration. Consistent with the measured MVO(2), the model-determined MV(17)O(2) showed a 92% increase at high Ca(2+) concentration. The increase in metabolic activity at high workload allowed the balance between ATP production and utilization to be maintained, leading to a similar phosphocreatine to ATP ratio. These results demonstrate that dynamic (17)O MRS can provide a valuable tool for the detection of an altered metabolic rate associated with a change in cardiac workload.

We present a novel approach to simultaneously measure, in vivo, noninvasively, glucose and oxygen consumption via Deuterium Magnetic Resonance (DMR). Mice are administered deuteriated glucose by intravenous injection. The rate of formation of nascent (deuteriated) mitochondrial water is then measured via DMR. The rate of glucose metabolism and oxygen utilization is assessed by tracking their separate peaks in DMR spectra during dynamic scanning. Further studies will aim to validate these results by comparison with in vivo (17)O-MRI (mitochondrial function), (13)C-MRI and (19)FDG-PET (glucose metabolism) and ex vivo 1H- and 2H-MR, as well as mass spectrometry.

We present a novel approach to simultaneously measure, in vivo, noninvasively, glucose and oxygen consumption via Deuterium Magnetic Resonance (DMR). Mice are administered deuteriated glucose by intravenous injection. The rate of formation of nascent (deuteriated) mitochondrial water is then measured via DMR. The rate of glucose metabolism and oxygen utilization is assessed by tracking their separate peaks in DMR spectra during dynamic scanning. Further studies will aim to validate these results by comparison with in vivo 17O-MRI (mitochondrial function), 13C-MRI and 19FDG-PET (glucose metabolism) and ex vivo 1H- and 2H-MR, as well as mass spectrometry.1

Functional oxygen-17 magnetic resonance (MR) imaging and localized spectroscopy is defined as the ensemble of MR measurements aiming at in vivo, noninvasive characterization of oxygen transport and utilization. After a brief description of the present status of in vivo 17O-MR, preliminary results are reported on oxygen delivery and consumption in cell suspensions of Saccharomyces cerevisiae. It is shown that parallel 31P-MR at high magnetic fields has an important corroborative value.

Functional oxygen-17 magnetic resonance (MR) imaging and localized spectroscopy is defined as the ensemble of MR measurements aiming at in vivo, noninvasive characterization of oxygen transport and utilization. After a brief description of the present status of in vivo 0-MR, preliminary results are reported on oxygen delivery and consumption in cell suspensions of Saccharomyces cerevisiae. It is shown that parallel P-MR at high magnetic fields has an important corroborative value.

The effects of protonation and hydrogen bonding in linear Schiff bases obtained from n-butylamine with butyraldehyde, crotonaldehyde, sorbaldehyde and all-trans-retinal were studied by means of 15N and 13C NMR. The protonation-induced chemical shifts (Δδ) are an order of magnitude larger for 15N than for 13C. For 15N, this effect was found to increase with the extent of conjugation, culminating in the retinylideneimine (Δδ = −146 ppm), which constitutes a model for the study of the structure of the Schiff base linkage in visual pigments and related systems. Theoretical calculations of protonation-induced Δδ values based on MINDO/ 3 are in agreement with experimental results.

The liver microsomal metabolism of the environmental carcinogen 3-nitrofluoranthene has been investigated. Five phenolic metabolites were isolated and characterized by their mass and NMR spectra as: 3-nitrofluoranthen-1-ol, 3-nitrofluoranthen-6-ol, 3-nitrofluoranthen-(7 or 10)-ol, 3-nitrofluoranthen-8-ol and 3-nitrofluoranthen-9-ol. While the microsomes isolated from Sprague-Dawley rat liver and C57B16 mouse liver preferentially metabolized the 3-nitrofluoranthene to 3-nitrofluoranthen-8-ol and 3-nitrofluoranthen-9-ol, the microsomes from Hartley guinea-pig liver preferentially metabolized 3-nitrofluoranthene to 3-nitrofluoranthen-6-ol. 3-Nitrofluoranthen-1-ol was a minor metabolite in each of the incubations. The results indicate the presence of the nitro group on fluoranthene directs the metabolism away from the C1-C5 positions, and more towards the C6-C10 positions.

The synthesis of retinals enriched with 13C at positions 11, 13, 14, 15, 12&20, 13&14, and 14&15 in high isomeric purity is reported. The importance of these retinals in studying the structure and properties of rhodopsin and bacteriorhodopsin by 13C NMR spectroscopy is briefly described.

Durch Addition von Brom an anti-Tricyclo[4.2.0.02.5]octadien-(3.7) (1) werden zwei isomere Tetrabromtricyclooctane 5 und 6 erhalten. Mit Basen spalten diese HBr ab und gehen in Dibromtricyclooctadien 7 uber. Beim Erhitzen lagern sich 5 und 6 in die isomeren Tetrabromverbindungen 13 und 14 um, welche ein Tricyclo[4.2.0.02.4]octan-Skelett enthalten.

Aus tert.-Butylacetylen und (C6H5CN)2·PdCl2 bildet sich der Tri-tert.-butyl-Dewar-Benzolpalladiumchlorid-Komplex 1. Bei dessen reduktiver Zersetzung entsteht ein Monochlorderivat mit Bicyclo[2.2.0]hexen-Skelett (10). In Gegenwart von Brom oder Jod geht 1 in ein Dichlorid mit Bicyclo[3.1.0]hexen-Skelett (19) uber. Unter dem Einflus von Sauren entsteht aus 10 ein Fulven 29.

Publisher Summary This chapter discusses the C nuclear magnetic resonance (nmr) spectroscopy of the chromophore of rhodopsin. C nmr spectroscopy has provided valuable information on the structure and function of water-soluble proteins. Rhodopsin is one membrane protein for which C nmr has proved feasible, as these drawbacks may be remedied by the introduction of a C enriched retinylidene chromophore and detergent solubilization. Solubilization by octyl glucoside enables high concentrations of rhodopsin to be obtained, as the lipids can be removed by chromatography and the detergent is not concentrated by ultrafiltration because of its high carboxymethyl cellulose (CMC). Octyl glucoside does not contribute resonances in the alkene region of the C nmr spectrum—that is, approximately 120–130 ppm. The rhodopsin/detergent micelle size appears to be relatively small, which leads to a short rotational correlation time and therefore narrow linewidths. The low ratio obtained for enriched rhodopsin indicates that free opsin is removed from regenerated rhodopsin during affinity chromatography, thereby maximizing the ratio.

This paper constitutes a chronological review of C-13 and N-15 solution and solid state NMR investigations of bovine rhodopsin and the purple membrane of Halobacterium halobium. Model retinylideneimines and their protonated species yielded rather informative variation in C-13 chemical shifts, as a function of structure and conformation, Retinals, specifically enriched with C-13 at key atom positions, were incorporated in rhodopsin and bacteriorhodopsin during the bleaching-regeneration process. The labeled pigments exhibited C-13 signals which were interpreted in terms of the state of protonation and conformation of the Schiff base linkage between the chromophore and opsin (15-anti in rhodopsin and light adapted bacteriorhodopsin) and chromophore-protein interactions. Peaks arising from both all-trans and 13-cis-retinylidene moieties were observed in dark adapted bacteriorhodopsin. Upon protonation, the Schiff base nitrogen of model compounds displayed dramatic (up to 146 ppm) high field N-15 shifts (an order of magnitude larger than C-13). Hydrogen bonding also led to important (up to 50 ppm) nitrogen shielding. H. halobium grown on a medium containing ɛ15N-lysine incorporated, with high yield, the labeled amino acid in all of the seven lysine sites of bacteriorhodopsin. Of these, one forms the shift could be observed only in lyophilized preparations. It appears that the degree of protonation of the Schiff base that the degree of protonation of the Schiff base linkage depends on the degree of hydation of the linkage depends on the degree of hydration of the specimen. Double labeling (13C=15N) is expected to provide valuable information concerning the structure and conformation of this moiety. The six lysine residues not involved in retinal binding yielded, in a micellar (octyl-β-glucoside) solution, N-15 signals of various linewidths, spread over a narrow (2–4 ppm) range. This could be interpreted in terms of lysine residue interactions within the protein. Preliminary results indicate the feasibility of in vivo measurements which avoid alterations inherent to extraction, purification, and/or lyophilization procedures.

Beim Losen von monomerem Formaldehyd bei -78°C in HF-SbF5 entsteht Fluormethylalkohol in seiner stabilen protonierten Form (F-CH2-OH2+).