K. Elbayed - Academia.edu (original) (raw)

Papers by K. Elbayed

Research paper thumbnail of Feasibility of NMR imaging by a single radiofrequency field gradient and the separation of two species with different chemical shifts

Journal of Magnetic Resonance (1969), 1991

The idea of substituting RF field gradients for static field gradients for localization or imagin... more The idea of substituting RF field gradients for static field gradients for localization or imaging purposes goes back to Hoult’s rotating-frame zeugmatography ( 1): further developments of this technique have been recently published (2). Obvious advantages of RF gradients lie in the possibility of rapid switching and in the simplicity of the experimental device, which essentially includes a single-turn coil in addition to a classical NMR probe. Most practical applications rely on two-dimensional methods (3-IO), the first dimension referring to a single spatial dimension, the other to a chemical-shift scale; such experiments therefore provide the distribution of different chemical species along that spatial direction. The present work is part of a project aimed at the use of a linear RF gradient for various NMR applications. These include measurements of self-diffusion coefficients (II), spatial localization by the adaptation of the classical DANTE sequence (12), slice selection, and ID imaging (13) through the recently proposed DANTE-Z procedure ( 14). We demonstrate here the possibility of obtaining a two-dimensional (eventually three-dimensional) image by means of a single coil delivering a RF gradient, in contrast with the applications mentioned, which concern only the examination of a single dimension. The successive exploration of the two dimensions is achieved by a fast rotation of the sample during an interval in an appropriate pulse sequence. Moreover, it is shown that a simple variant of this experiment allows one to perform imaging of two chemically shifted species within the same experiment. The experimental arrangement in use ( I1 -13) can be summarized as follows: (i) surrounding the sample is a normal saddle-shaped coil which is employed for generating hard homogeneous pulses and for detecting the NMR signal, (ii) a single-turn coil, orthogonal to the saddle-shaped coil, delivers a linear RF gradient in the sample region (Fig. 1). and (iii) two different transmitters feed these two coils, at the same RF frequency, but with the possibility of adjusting their relative phases so that they can operate in the same rotating frame. The rotation of the object under investigation could be replaced (and probably will be in the near future) by a rotation of the two-coil system.

Research paper thumbnail of Slice selection in NMR imaging by use of the B1 gradient along the axial direction of a saddle-shaped coil

Journal of Magnetic Resonance (1969), 1991

Research paper thumbnail of Self-diffusion measurements using a radiofrequency field gradient

Journal of Magnetic Resonance (1969), 1989

Research paper thumbnail of A statistical framework for biomarker identification of biopsies using HR-MAS HSQC spectroscopy

2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro, 2011

... Akram BELGHITH 1,2 , Christophe COLLET 1 and Jean-Paul ARMSPACH 2 ... Karim ELBAYED and Dr Iz... more ... Akram BELGHITH 1,2 , Christophe COLLET 1 and Jean-Paul ARMSPACH 2 ... Karim ELBAYED and Dr Izzie Jacque NAMER from Department of Biophysics and Nuclear Medicine, University Hospitals of Strasbourg for HSQC biopsies spectra and for results validation. ...

Research paper thumbnail of Accurate determination of interference terms between carbon-proton dipolar interactions and carbon or proton chemical shift anisotropy from longitudinal carbon-13 relaxation studies

Molecular Physics, 1989

CSA (chemical shift anisotropy)-dipolar cross-correlation densities (also named CSA-dipolar inter... more CSA (chemical shift anisotropy)-dipolar cross-correlation densities (also named CSA-dipolar interference terms) may couple longitudinal nuclear magnetizations of a two spin 1/2 system (in the present case, carbon-13 and proton magnetizations) with the magnetization mode . A pulse sequence has been devised for converting , created by the relaxation arising from CSA-dipolar interference, into observable transverse carbon-13 magnetization. Because of the weakness of interference terms, drastic precautions have been taken to eliminate all other contributions. An account of the theory underlying these experiments is given. It includes aspects of spin dynamics and the derivation of cross-correlation spectral densities expressed within the ‘two-step model’ (or the ‘model free approach’), which is particularly well suited for treating dynamics of large molecules or of organized systems, A micellized surfactant, which possesses an aromatic ring bearing the polar head, prov...

Research paper thumbnail of Behaviour of a coupled two-spin-1/2 system in the presence of a spin-locking radio-frequency field. Relaxation and Hartmann-Hahn transfers

Molecular Physics, 1990

The theory of the evolution of a J-coupled homonuclear system of two nuclei of spin 1/2 (in the l... more The theory of the evolution of a J-coupled homonuclear system of two nuclei of spin 1/2 (in the liquid state) subjected to a spin-locking field is explicitly reformulated in terms of simultaneous differential equations. Quantities destroyed by the inhomogeneity of the spin-locking field are delineated; from these considerations it is found that only four quantities interfere: the two transverse magnetizations of concern (supposed to be in absorption), one observable mode corresponding to the difference of antiphase dispersive doublets and one mode (unobservable) involving zero/double quantum coherences. Transfers of Hartmann-Hahn type occur necessarily via the antiphase doublet mode. Analytical solutions could be derived for these transfers, which occur in an oscillatory fashion. The frequency of the Hartmann-Hahn oscillations is shown to depend not only upon J but also upon the characteristics of the spin-locking field (amplitude and offset with respect to the resonance frequencies of the two nuclei). When relaxation phenomena are included, the resulting differential equations are no longer analytically solvable. Approximate treatments, as well as an exact numerical analysis, lead to the conclusion that Hartmann-Hahn oscillations always exist as long as the J coupling is not too small with regard to relaxation parameters, their amplitude decreasing when the amplitude of the spin-locking field decreases. The numerical analysis allows extraction, from experimental data, of the relaxation parameters and particularly the transverse cross-relaxation term. Experimental one-dimensional results confirm the validity of the present theory. Implications for the intensities of cross-peaks in two-dimensional ROESY experiments are outlined.

Research paper thumbnail of 1 H and 23 Na NMR Relaxation Studies of the NaCl/?-Lactoglobulin System Equilibrated at Various Water Activities

Journal of Food Science, 1989

ABSTRACT ABSTRACTNMR relaxation times (T1) of 1H and 23Na were determined at 8, 14, 60, MHz and a... more ABSTRACT ABSTRACTNMR relaxation times (T1) of 1H and 23Na were determined at 8, 14, 60, MHz and at 14, 52 MHz, respectively, in the NaCl/β-lactoglobulin system equilibrated at water activities ranging from 0.11 to 0.97. A two-state model was used for both nuclei which allowed the calculation of proportions of bound and free species. It was shown that bound water and Na+ increased at medium water activities in the presence of increasing NaCl. The discrepancy with adsorption isotherms data was explained by (1) limitations of the mass balance equation used to calculate interacting salt by gravimetry and (2) the fact that NMR probed the totality of ions in the vicinity of the protein, whereas adsorption isotherms were indicative of sodium choride tightly bound to the protein. It was also shown that the protein and Na+ shared available water molecules at medium and low water activity.

Research paper thumbnail of Heteronuclear double cross-polarization (1H−X; X−1H) transfer in liquids

Chemical Physics Letters, 1990

Abstract Hartmann—Hahn cross-polarization transfers in liquids are used for correlating two J -co... more Abstract Hartmann—Hahn cross-polarization transfers in liquids are used for correlating two J -coupled nuclei of different istopic nature. It is explained why continuous-wave spin-locking fields are difficult to use and have to be replaced by phase-modulated fields which compensate for inhomogeneity effects. Cross-polarization procedures are applied twice: firstly for transferring proton polarization to an X nucleus; secondly, after saturation of all non-involved proton transitions, from X to proton. The subsequent proton acquisition ensures optimal sensitivity. The proposed method, in contrast with the widely used HMQC sequence, provides in-phase responses.

Research paper thumbnail of Automatic phase correction of Fourier-transform NMR data and estimation of peak area by fitting to a Lorentzian shape

Analytical Chemistry, 1990

Research paper thumbnail of Superfast T1 determination by inversion-recovery

Journal of Magnetic Resonance (1969), 1988

Research paper thumbnail of Research Article Metabolomic Characterization of Ovarian Epithelial Carcinomas by HRMAS-NMR Spectroscopy

Copyright © 2011 D. Ben Sellem et al. This is an open access article distributed under the Creati... more Copyright © 2011 D. Ben Sellem et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives. The objectives of the present study are to determine if a metabolomic study by HRMAS-NMR can (i) discriminate between different histological types of epithelial ovarian carcinomas and healthy ovarian tissue, (ii) generate statistical models capable of classifying borderline tumors and (iii) establish a potential relationship with patient’s survival or response to chemotherapy. Methods. 36 human epithelial ovarian tumor biopsies and 3 healthy ovarian tissues were studied using 1 H HRMAS NMR spectroscopy and multivariate statistical analysis. Results. The results presented in this study demonstrate that the three histological types of epithelial ovarian carcinomas present an effective metabolic pattern difference. Furthermor...

Research paper thumbnail of AB0173 Metabolomics in Primary SjÖgren's Syndrome: Data from the Assess Cohort

Annals of the Rheumatic Diseases, 2015

Background High throughput study of metabolic pathways might help identify new biomarkers and the... more Background High throughput study of metabolic pathways might help identify new biomarkers and therapeutic targets in autoimmune diseases. Primary Sjögren's syndrome (pSS) currently lacks prognostic biomarkers and efficacious and specific treatments. We therefore assessed serum levels of 35 metabolites in pSS using high-resolution magic-angle spinning (HRMAS) proton magnetic resonance spectroscopy. Methods The blood samples of 194 patients with pSS enrolled in the prospective multicenter ASSESS cohort and 41 blood donors were analysed in this study. After cryopreservation at -80°C, the samples were studied with HRMAS proton magnetic resonance spectroscopy (1H-MRS). Spectra were recorded on a Bruker Avance III 500 spectrometer operating at a proton frequency of 500 MHz. All the 1D NMR spectra were acquired during 76 min. Supervised clustering was performed on the spectral region between 0.5 and 4.7 ppm using partial least square discriminant analysis (PLS-DA). Results Supervised clustering of the 194 samples allowed to discriminate all patients with pSS from healthy controls (R2Y=0.88 and Q2=0.86 (figure 1)). Interestingly, 4 serum metabolites were significantly increased in pSS compared to healthy controls: threonine, lactate, glutamine and acetate. 6 metabolites were significantly decreased in pSS compared to healthy controls: myo-inositol, creatine, lysine, aspartate, glutamate and alanine Conclusions This first high-throughput analysis of metabolic pathways disclosed a specific metabolomic signature of pSS allowing discriminating all patients with pSS from controls. This new and very potent means of metabolic analysis may help to increase our knowledge on the pathogenesis of pSS, identify biomarkers, and new therapeutic targets. Disclosure of Interest None declared

Research paper thumbnail of Microondes

Research paper thumbnail of Que Peut-on faire avec un noyau quadrupolaire en RMN ? Un exemple avec le cobalt 59

Journal de Chimie Physique et de Physico-Chimie Biologique, 1999

La RMN de cobalt 59 a été observée sur des clusters tétraédriques en solution et en phase solide.... more La RMN de cobalt 59 a été observée sur des clusters tétraédriques en solution et en phase solide. En utilisant les temps de relaxation en solution, on peut en déduire les constantes de couplage quadrupolaires pour "Ru et le spectre en phase solide théorique des atomes basaux de Co4(CO)|2 jamais observés. Cette courte revue montre tout l'intérêt des hauts champs appliqués aux noyaux quadrupolaires.

Research paper thumbnail of Simple correction of chemical shift changes in magnetic resonance spectroscopy quantitation

2010 IEEE International Conference on Imaging Systems and Techniques, 2010

High-resolution magic angle spinning (HRMAS) 1 H spectroscopy is playing an increasingly importan... more High-resolution magic angle spinning (HRMAS) 1 H spectroscopy is playing an increasingly important role for diagnosis. This technique enables setting up metabolite profiles of ex vivo pathological and healthy tissue. Automatic quantitation of HRMAS signals provides reliable reference profiles to monitor diseases and pharmaceutical follow-up. Nevertheless, for several metabolites chemical shifts may slightly differ according to the micro-environment in the tissue or cells, in particular its pH. This hampers accurate estimation of the metabolite concentrations mainly when using quantitation algorithms based on a metabolite basis-set. In this work, we propose a user-friendly way to circumvent this problem based on stretching of the metabolite basis-set signals and maximization of the correlation between the HRMAS and basis-set spectra prior to quantitation.

Research paper thumbnail of Rapid Assessment of Fish Freshness and Quality by 1H HR-MAS NMR Spectroscopy

Food Analytical Methods, 2014

A new analytical method that allows the rapid assessment of fish freshness and quality is present... more A new analytical method that allows the rapid assessment of fish freshness and quality is presented. The method is based on 1 H high-resolution magic angle spinning (HR-MAS) NMR spectroscopy and allows the rapid determination of two well-established indicators of fish freshness and quality: the K value and the trimethylamine nitrogen (TMA-N) content. The method is demonstrated on four different species of fish (sea bream, sea bass, trout, and red mullet) stored on ice at 0°C. The results obtained are in agreement with more cumbersome methods classically used to determine the K value and the TMA-N concentration. The main advantage of the 1 H HR-MAS NMR approach is to allow a direct measurement of these two parameters directly on unprocessed fish sample without using any preliminary extraction. The total analysis time, including sample preparation, is of the order of 40 min per sample.

Research paper thumbnail of Utilité de l’étude métabolique du sérum par spectroscopie (HRMAS-NMR) pour distinguer la neuromyélite optique et la sclérose en plaques

Research paper thumbnail of Serum analysis by1H Nuclear Magnetic Resonance spectroscopy: a new tool for distinguishing neuromyelitis optica from multiple sclerosis

Multiple Sclerosis Journal, 2013

Background:Neuromyelitis optica (NMO) and multiple sclerosis (MS), two inflammatory demyelinating... more Background:Neuromyelitis optica (NMO) and multiple sclerosis (MS), two inflammatory demyelinating diseases, are characterized by different therapeutic strategies. Currently, the only biological diagnostic tool available to distinguish NMO from MS is the specific serum autoantibody that targets aquaporin 4, but its sensitivity is low.Objective:To assess the diagnostic accuracy of metabolomic biomarker profiles in these two neurological conditions, compared to control patients.Methods:We acquired serum spectra (47 MS, 44 NMO and 42 controls) using proton nuclear magnetic resonance (1H-NMR) spectroscopy. We used multivariate pattern recognition analysis to identify disease-specific metabolic profiles.Results:The1H-NMR spectroscopic analysis evidenced two metabolites, originating probably from astrocytes, scyllo-inositol and acetate, as promising serum biomarkers of MS and NMO, respectively. In 87.8% of MS patients, scyllo-inositol increased 0.15 to 3-fold, compared to controls and in 7...

Research paper thumbnail of Microdynamic motion of tetrahedral clusters studied by 59Co and 99Ru NMR relaxations

Molecular Physics, 1997

The microdynamic motions of the clusters A[MCo (CO) ] (A = H, NEt ; M = Fe, Ru) and HFeCo (CO) [P... more The microdynamic motions of the clusters A[MCo (CO) ] (A = H, NEt ; M = Fe, Ru) and HFeCo (CO) [P(OCH ) ] have been studied for the first time using 59Co NMR spectroscopy. The chemical shift anisotropies and the quadrupolar coupling constants known from solid state NMR results allow a direct determination of the correlation times in solution

Research paper thumbnail of Investigation of the surfactants in CTAB-templated mesoporous silica by 1H HRMAS NMR

Microporous and Mesoporous Materials, 2003

High resolution magic angle spinning (HRMAS) leads to nearly liquid-state quality NMR spectra of ... more High resolution magic angle spinning (HRMAS) leads to nearly liquid-state quality NMR spectra of molecules with restrained mobility. We show here how 1 H HRMAS can be applied to organic molecules encapsulated inside mesoporous materials. We investigated an uncalcined surfactant-templated mesoporous silica synthesized from a mixture of cationic and anionic surfactants, CTAB and HPMSP. The pyrazolone HPMSP is adding cation-extracting properties to the silica, which contains 60% of organic compounds in weight. MAS NMR at moderate spinning speeds allows to resolve proton spectra on samples where a small amount of methanol is added to the dried as-synthesized silica. NMR experiments allow to distinguish between solvated surfactants involved in ion pairs and less mobile templating surfactants. Liquid state NMR experiments like 2D NOESY can be performed in these conditions, but suffer from spin diffusion. 1D and 2D solidstate NMR experiments, like Rotational Resonance, which take advantage of the partly solid-state behavior of the surfactant system, are proposed as alternative experiments to get information about spatial connectivity.

Research paper thumbnail of Feasibility of NMR imaging by a single radiofrequency field gradient and the separation of two species with different chemical shifts

Journal of Magnetic Resonance (1969), 1991

The idea of substituting RF field gradients for static field gradients for localization or imagin... more The idea of substituting RF field gradients for static field gradients for localization or imaging purposes goes back to Hoult’s rotating-frame zeugmatography ( 1): further developments of this technique have been recently published (2). Obvious advantages of RF gradients lie in the possibility of rapid switching and in the simplicity of the experimental device, which essentially includes a single-turn coil in addition to a classical NMR probe. Most practical applications rely on two-dimensional methods (3-IO), the first dimension referring to a single spatial dimension, the other to a chemical-shift scale; such experiments therefore provide the distribution of different chemical species along that spatial direction. The present work is part of a project aimed at the use of a linear RF gradient for various NMR applications. These include measurements of self-diffusion coefficients (II), spatial localization by the adaptation of the classical DANTE sequence (12), slice selection, and ID imaging (13) through the recently proposed DANTE-Z procedure ( 14). We demonstrate here the possibility of obtaining a two-dimensional (eventually three-dimensional) image by means of a single coil delivering a RF gradient, in contrast with the applications mentioned, which concern only the examination of a single dimension. The successive exploration of the two dimensions is achieved by a fast rotation of the sample during an interval in an appropriate pulse sequence. Moreover, it is shown that a simple variant of this experiment allows one to perform imaging of two chemically shifted species within the same experiment. The experimental arrangement in use ( I1 -13) can be summarized as follows: (i) surrounding the sample is a normal saddle-shaped coil which is employed for generating hard homogeneous pulses and for detecting the NMR signal, (ii) a single-turn coil, orthogonal to the saddle-shaped coil, delivers a linear RF gradient in the sample region (Fig. 1). and (iii) two different transmitters feed these two coils, at the same RF frequency, but with the possibility of adjusting their relative phases so that they can operate in the same rotating frame. The rotation of the object under investigation could be replaced (and probably will be in the near future) by a rotation of the two-coil system.

Research paper thumbnail of Slice selection in NMR imaging by use of the B1 gradient along the axial direction of a saddle-shaped coil

Journal of Magnetic Resonance (1969), 1991

Research paper thumbnail of Self-diffusion measurements using a radiofrequency field gradient

Journal of Magnetic Resonance (1969), 1989

Research paper thumbnail of A statistical framework for biomarker identification of biopsies using HR-MAS HSQC spectroscopy

2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro, 2011

... Akram BELGHITH 1,2 , Christophe COLLET 1 and Jean-Paul ARMSPACH 2 ... Karim ELBAYED and Dr Iz... more ... Akram BELGHITH 1,2 , Christophe COLLET 1 and Jean-Paul ARMSPACH 2 ... Karim ELBAYED and Dr Izzie Jacque NAMER from Department of Biophysics and Nuclear Medicine, University Hospitals of Strasbourg for HSQC biopsies spectra and for results validation. ...

Research paper thumbnail of Accurate determination of interference terms between carbon-proton dipolar interactions and carbon or proton chemical shift anisotropy from longitudinal carbon-13 relaxation studies

Molecular Physics, 1989

CSA (chemical shift anisotropy)-dipolar cross-correlation densities (also named CSA-dipolar inter... more CSA (chemical shift anisotropy)-dipolar cross-correlation densities (also named CSA-dipolar interference terms) may couple longitudinal nuclear magnetizations of a two spin 1/2 system (in the present case, carbon-13 and proton magnetizations) with the magnetization mode . A pulse sequence has been devised for converting , created by the relaxation arising from CSA-dipolar interference, into observable transverse carbon-13 magnetization. Because of the weakness of interference terms, drastic precautions have been taken to eliminate all other contributions. An account of the theory underlying these experiments is given. It includes aspects of spin dynamics and the derivation of cross-correlation spectral densities expressed within the ‘two-step model’ (or the ‘model free approach’), which is particularly well suited for treating dynamics of large molecules or of organized systems, A micellized surfactant, which possesses an aromatic ring bearing the polar head, prov...

Research paper thumbnail of Behaviour of a coupled two-spin-1/2 system in the presence of a spin-locking radio-frequency field. Relaxation and Hartmann-Hahn transfers

Molecular Physics, 1990

The theory of the evolution of a J-coupled homonuclear system of two nuclei of spin 1/2 (in the l... more The theory of the evolution of a J-coupled homonuclear system of two nuclei of spin 1/2 (in the liquid state) subjected to a spin-locking field is explicitly reformulated in terms of simultaneous differential equations. Quantities destroyed by the inhomogeneity of the spin-locking field are delineated; from these considerations it is found that only four quantities interfere: the two transverse magnetizations of concern (supposed to be in absorption), one observable mode corresponding to the difference of antiphase dispersive doublets and one mode (unobservable) involving zero/double quantum coherences. Transfers of Hartmann-Hahn type occur necessarily via the antiphase doublet mode. Analytical solutions could be derived for these transfers, which occur in an oscillatory fashion. The frequency of the Hartmann-Hahn oscillations is shown to depend not only upon J but also upon the characteristics of the spin-locking field (amplitude and offset with respect to the resonance frequencies of the two nuclei). When relaxation phenomena are included, the resulting differential equations are no longer analytically solvable. Approximate treatments, as well as an exact numerical analysis, lead to the conclusion that Hartmann-Hahn oscillations always exist as long as the J coupling is not too small with regard to relaxation parameters, their amplitude decreasing when the amplitude of the spin-locking field decreases. The numerical analysis allows extraction, from experimental data, of the relaxation parameters and particularly the transverse cross-relaxation term. Experimental one-dimensional results confirm the validity of the present theory. Implications for the intensities of cross-peaks in two-dimensional ROESY experiments are outlined.

Research paper thumbnail of 1 H and 23 Na NMR Relaxation Studies of the NaCl/?-Lactoglobulin System Equilibrated at Various Water Activities

Journal of Food Science, 1989

ABSTRACT ABSTRACTNMR relaxation times (T1) of 1H and 23Na were determined at 8, 14, 60, MHz and a... more ABSTRACT ABSTRACTNMR relaxation times (T1) of 1H and 23Na were determined at 8, 14, 60, MHz and at 14, 52 MHz, respectively, in the NaCl/β-lactoglobulin system equilibrated at water activities ranging from 0.11 to 0.97. A two-state model was used for both nuclei which allowed the calculation of proportions of bound and free species. It was shown that bound water and Na+ increased at medium water activities in the presence of increasing NaCl. The discrepancy with adsorption isotherms data was explained by (1) limitations of the mass balance equation used to calculate interacting salt by gravimetry and (2) the fact that NMR probed the totality of ions in the vicinity of the protein, whereas adsorption isotherms were indicative of sodium choride tightly bound to the protein. It was also shown that the protein and Na+ shared available water molecules at medium and low water activity.

Research paper thumbnail of Heteronuclear double cross-polarization (1H−X; X−1H) transfer in liquids

Chemical Physics Letters, 1990

Abstract Hartmann—Hahn cross-polarization transfers in liquids are used for correlating two J -co... more Abstract Hartmann—Hahn cross-polarization transfers in liquids are used for correlating two J -coupled nuclei of different istopic nature. It is explained why continuous-wave spin-locking fields are difficult to use and have to be replaced by phase-modulated fields which compensate for inhomogeneity effects. Cross-polarization procedures are applied twice: firstly for transferring proton polarization to an X nucleus; secondly, after saturation of all non-involved proton transitions, from X to proton. The subsequent proton acquisition ensures optimal sensitivity. The proposed method, in contrast with the widely used HMQC sequence, provides in-phase responses.

Research paper thumbnail of Automatic phase correction of Fourier-transform NMR data and estimation of peak area by fitting to a Lorentzian shape

Analytical Chemistry, 1990

Research paper thumbnail of Superfast T1 determination by inversion-recovery

Journal of Magnetic Resonance (1969), 1988

Research paper thumbnail of Research Article Metabolomic Characterization of Ovarian Epithelial Carcinomas by HRMAS-NMR Spectroscopy

Copyright © 2011 D. Ben Sellem et al. This is an open access article distributed under the Creati... more Copyright © 2011 D. Ben Sellem et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives. The objectives of the present study are to determine if a metabolomic study by HRMAS-NMR can (i) discriminate between different histological types of epithelial ovarian carcinomas and healthy ovarian tissue, (ii) generate statistical models capable of classifying borderline tumors and (iii) establish a potential relationship with patient’s survival or response to chemotherapy. Methods. 36 human epithelial ovarian tumor biopsies and 3 healthy ovarian tissues were studied using 1 H HRMAS NMR spectroscopy and multivariate statistical analysis. Results. The results presented in this study demonstrate that the three histological types of epithelial ovarian carcinomas present an effective metabolic pattern difference. Furthermor...

Research paper thumbnail of AB0173 Metabolomics in Primary SjÖgren's Syndrome: Data from the Assess Cohort

Annals of the Rheumatic Diseases, 2015

Background High throughput study of metabolic pathways might help identify new biomarkers and the... more Background High throughput study of metabolic pathways might help identify new biomarkers and therapeutic targets in autoimmune diseases. Primary Sjögren's syndrome (pSS) currently lacks prognostic biomarkers and efficacious and specific treatments. We therefore assessed serum levels of 35 metabolites in pSS using high-resolution magic-angle spinning (HRMAS) proton magnetic resonance spectroscopy. Methods The blood samples of 194 patients with pSS enrolled in the prospective multicenter ASSESS cohort and 41 blood donors were analysed in this study. After cryopreservation at -80°C, the samples were studied with HRMAS proton magnetic resonance spectroscopy (1H-MRS). Spectra were recorded on a Bruker Avance III 500 spectrometer operating at a proton frequency of 500 MHz. All the 1D NMR spectra were acquired during 76 min. Supervised clustering was performed on the spectral region between 0.5 and 4.7 ppm using partial least square discriminant analysis (PLS-DA). Results Supervised clustering of the 194 samples allowed to discriminate all patients with pSS from healthy controls (R2Y=0.88 and Q2=0.86 (figure 1)). Interestingly, 4 serum metabolites were significantly increased in pSS compared to healthy controls: threonine, lactate, glutamine and acetate. 6 metabolites were significantly decreased in pSS compared to healthy controls: myo-inositol, creatine, lysine, aspartate, glutamate and alanine Conclusions This first high-throughput analysis of metabolic pathways disclosed a specific metabolomic signature of pSS allowing discriminating all patients with pSS from controls. This new and very potent means of metabolic analysis may help to increase our knowledge on the pathogenesis of pSS, identify biomarkers, and new therapeutic targets. Disclosure of Interest None declared

Research paper thumbnail of Microondes

Research paper thumbnail of Que Peut-on faire avec un noyau quadrupolaire en RMN ? Un exemple avec le cobalt 59

Journal de Chimie Physique et de Physico-Chimie Biologique, 1999

La RMN de cobalt 59 a été observée sur des clusters tétraédriques en solution et en phase solide.... more La RMN de cobalt 59 a été observée sur des clusters tétraédriques en solution et en phase solide. En utilisant les temps de relaxation en solution, on peut en déduire les constantes de couplage quadrupolaires pour "Ru et le spectre en phase solide théorique des atomes basaux de Co4(CO)|2 jamais observés. Cette courte revue montre tout l'intérêt des hauts champs appliqués aux noyaux quadrupolaires.

Research paper thumbnail of Simple correction of chemical shift changes in magnetic resonance spectroscopy quantitation

2010 IEEE International Conference on Imaging Systems and Techniques, 2010

High-resolution magic angle spinning (HRMAS) 1 H spectroscopy is playing an increasingly importan... more High-resolution magic angle spinning (HRMAS) 1 H spectroscopy is playing an increasingly important role for diagnosis. This technique enables setting up metabolite profiles of ex vivo pathological and healthy tissue. Automatic quantitation of HRMAS signals provides reliable reference profiles to monitor diseases and pharmaceutical follow-up. Nevertheless, for several metabolites chemical shifts may slightly differ according to the micro-environment in the tissue or cells, in particular its pH. This hampers accurate estimation of the metabolite concentrations mainly when using quantitation algorithms based on a metabolite basis-set. In this work, we propose a user-friendly way to circumvent this problem based on stretching of the metabolite basis-set signals and maximization of the correlation between the HRMAS and basis-set spectra prior to quantitation.

Research paper thumbnail of Rapid Assessment of Fish Freshness and Quality by 1H HR-MAS NMR Spectroscopy

Food Analytical Methods, 2014

A new analytical method that allows the rapid assessment of fish freshness and quality is present... more A new analytical method that allows the rapid assessment of fish freshness and quality is presented. The method is based on 1 H high-resolution magic angle spinning (HR-MAS) NMR spectroscopy and allows the rapid determination of two well-established indicators of fish freshness and quality: the K value and the trimethylamine nitrogen (TMA-N) content. The method is demonstrated on four different species of fish (sea bream, sea bass, trout, and red mullet) stored on ice at 0°C. The results obtained are in agreement with more cumbersome methods classically used to determine the K value and the TMA-N concentration. The main advantage of the 1 H HR-MAS NMR approach is to allow a direct measurement of these two parameters directly on unprocessed fish sample without using any preliminary extraction. The total analysis time, including sample preparation, is of the order of 40 min per sample.

Research paper thumbnail of Utilité de l’étude métabolique du sérum par spectroscopie (HRMAS-NMR) pour distinguer la neuromyélite optique et la sclérose en plaques

Research paper thumbnail of Serum analysis by1H Nuclear Magnetic Resonance spectroscopy: a new tool for distinguishing neuromyelitis optica from multiple sclerosis

Multiple Sclerosis Journal, 2013

Background:Neuromyelitis optica (NMO) and multiple sclerosis (MS), two inflammatory demyelinating... more Background:Neuromyelitis optica (NMO) and multiple sclerosis (MS), two inflammatory demyelinating diseases, are characterized by different therapeutic strategies. Currently, the only biological diagnostic tool available to distinguish NMO from MS is the specific serum autoantibody that targets aquaporin 4, but its sensitivity is low.Objective:To assess the diagnostic accuracy of metabolomic biomarker profiles in these two neurological conditions, compared to control patients.Methods:We acquired serum spectra (47 MS, 44 NMO and 42 controls) using proton nuclear magnetic resonance (1H-NMR) spectroscopy. We used multivariate pattern recognition analysis to identify disease-specific metabolic profiles.Results:The1H-NMR spectroscopic analysis evidenced two metabolites, originating probably from astrocytes, scyllo-inositol and acetate, as promising serum biomarkers of MS and NMO, respectively. In 87.8% of MS patients, scyllo-inositol increased 0.15 to 3-fold, compared to controls and in 7...

Research paper thumbnail of Microdynamic motion of tetrahedral clusters studied by 59Co and 99Ru NMR relaxations

Molecular Physics, 1997

The microdynamic motions of the clusters A[MCo (CO) ] (A = H, NEt ; M = Fe, Ru) and HFeCo (CO) [P... more The microdynamic motions of the clusters A[MCo (CO) ] (A = H, NEt ; M = Fe, Ru) and HFeCo (CO) [P(OCH ) ] have been studied for the first time using 59Co NMR spectroscopy. The chemical shift anisotropies and the quadrupolar coupling constants known from solid state NMR results allow a direct determination of the correlation times in solution

Research paper thumbnail of Investigation of the surfactants in CTAB-templated mesoporous silica by 1H HRMAS NMR

Microporous and Mesoporous Materials, 2003

High resolution magic angle spinning (HRMAS) leads to nearly liquid-state quality NMR spectra of ... more High resolution magic angle spinning (HRMAS) leads to nearly liquid-state quality NMR spectra of molecules with restrained mobility. We show here how 1 H HRMAS can be applied to organic molecules encapsulated inside mesoporous materials. We investigated an uncalcined surfactant-templated mesoporous silica synthesized from a mixture of cationic and anionic surfactants, CTAB and HPMSP. The pyrazolone HPMSP is adding cation-extracting properties to the silica, which contains 60% of organic compounds in weight. MAS NMR at moderate spinning speeds allows to resolve proton spectra on samples where a small amount of methanol is added to the dried as-synthesized silica. NMR experiments allow to distinguish between solvated surfactants involved in ion pairs and less mobile templating surfactants. Liquid state NMR experiments like 2D NOESY can be performed in these conditions, but suffer from spin diffusion. 1D and 2D solidstate NMR experiments, like Rotational Resonance, which take advantage of the partly solid-state behavior of the surfactant system, are proposed as alternative experiments to get information about spatial connectivity.