Biomarqueurs prédictifs de la maladie d'Alzheimer dans un modèle de souris : approche métabolomique par spectroscopies RMN et études comportementales

La maladie d'Alzheimer (MA) est un trouble neurodégénératif lié à l'âge entraînant une diminution des fonctions cognitives. Les traitements actuels ne sont que symptomatiques. Il en résulte un besoin urgent d'outils diagnostiques permettant de déceler la MA avant les premiers signes de déclin cognitif. Une étude métabolomique par RMN 1H a tout d'abord été réalisée sur cinq parties de cerveau de souris contrôles (Tg-) ou développant une démence amyloïde (Tg+) âgées de 1 à 11 mois afin de caractériser les perturbations métaboliques associées au développement de la MA. L'hippocampe (Hipp) est métaboliquement affecté précocement au cours de l'évolution de la MA. La taurine (Tau) et la créatine (Cr), métabolites neuroprotecteurs et osmorégulateurs, augmentent dans l'Hipp des Tg+ dès l'âge de 6 mois. La SRM et la RMN 1H ont ensuite été couplées pour analyser l'Hipp de jeunes souris traitées au clioquinol (CQ). Le CQ accroît la formation de Tau et Cr avant les premiers signes de déclin cognitif. Enfin, des tests comportementaux ont été réalisés sur des souris de 13 mois dans un environnement enrichi (EE) ou traitées par du CQ. Les profils métaboliques ont été analysés par RMN 1H. L'EE et le CQ ont amélioré la mémoire épisodique des Tg+ lorsqu'elles étaient dans un environnement familier. Aucune différence métabolique n'a pu être mise en évidence dans l'Hipp en fonction du génotype. Le couplage statistique des données comportementales et métabolomiques a montré que les Tg+ non traitées au CQ ou non EE développaient des troubles de la mémoire épisodique associés à une concentration de Tau et Cr plus élevée. Ainsi, un EE précoce ou un traitement tardif au CQ améliorerait les fonctions cognitives même à un âge où les plaques amyloïdes sont apparues.Alzheimer's disease (AD) is an age-dependent neurodegenerative disorder that causes a progressive decline in cognitive functions. Current treatments are only symptomatic. So, there is an urgent need for diagnostic tools able to detect AD prior to the onset of signs of cognitive impairment. A metabolomic study by 1H NMR was first carried out on five brain regions of control (Tg-) or amyloidopathy-developing mice (Tg+) aged 1 to 11 months to characterize the metabolic alterations linked to the development of AD. The hippocampus (Hipp) is metabolically affected early during the progression of AD. Taurine (Tau) and creatine (Cr), two neuroprotective and osmoregulatory metabolites, increase in the Hipp of Tg+ from the age of 6 months. 1H SRM and NMR were then coupled to analyze the Hipp of young mice treated with clioquinol (CQ). CQ increases the formation of Tau and Cr before the first signs of cognitive decline. Finally, behavioral tests were performed on 13 month-old mice in an enriched environment (EE) or treated by CQ. The metabolic profiles were analyzed by 1H NMR. The EE and CQ improved episodic memory of Tg+ when they were in a familiar environment. No metabolic difference between control and transgenic mice could be demonstrated in the Hipp. The statistical coupling of metabolomic and behavioral data showed that untreated-CQ and non-EE Tg+ mice developed disorders of episodic memory associated with higher Cr and Tau concentrations. Thus, an early EE or a late CQ treatment would improve cognitive functions even at an age when amyloid plaques have started to form

Green Edge ice camp campaigns : understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies

Progressive exercise compared with best practice advice, with or without corticosteroid injection, for the treatment of patients with rotator cuff disorders (GRASP): a multicentre, pragmatic, 2 × 2 factorial, randomised controlled trial

Background Corticosteroid injections and physiotherapy exercise programmes are commonly used to treat rotator cuff disorders but the treatments' effectiveness is uncertain. We aimed to compare the clinical effectiveness and cost-effectiveness of a progressive exercise programme with a single session of best practice physiotherapy advice, with or without corticosteroid injection, in adults with a rotator cuff disorder. Methods In this pragmatic, multicentre, superiority, randomised controlled trial (2 × 2 factorial), we recruited patients from 20 UK National Health Service trusts. We included patients aged 18 years or older with a rotator cuff disorder (new episode within the past 6 months). Patients were excluded if they had a history of significant shoulder trauma (eg, dislocation, fracture, or full-thickness tear requiring surgery), neurological disease affecting the shoulder, other shoulder conditions (eg, inflammatory arthritis, frozen shoulder, or glenohumeral joint instability), received corticosteroid injection or physiotherapy for shoulder pain in the past 6 months, or were being considered for surgery. Patients were randomly assigned (centralised computer-generated system, 1:1:1:1) to progressive exercise (≤6 sessions), best practice advice (one session), corticosteroid injection then progressive exercise, or corticosteroid injection then best practice advice. The primary outcome was the Shoulder Pain and Disability Index (SPADI) score over 12 months, analysed on an intention-to-treat basis (statistical significance set at 1%). The trial was registered with the International Standard Randomised Controlled Trial Register, ISRCTN16539266, and EuDRACT, 2016-002991-28. Findings Between March 10, 2017, and May 2, 2019, we screened 2287 patients. 708 patients were randomly assigned to progressive exercise (n=174), best practice advice (n=174), corticosteroid injection then progressive exercise (n=182), or corticosteroid injection then best practice advice (n=178). Over 12 months, SPADI data were available for 166 (95%) patients in the progressive exercise group, 164 (94%) in the best practice advice group, 177 (97%) in the corticosteroid injection then progressive exercise group, and 175 (98%) in the corticosteroid injection then best practice advice group. We found no evidence of a difference in SPADI score between progressive exercise and best practice advice when analysed over 12 months (adjusted mean difference −0·66 [99% CI −4·52 to 3·20]). We also found no evidence of a difference between corticosteroid injection compared with no injection when analysed over 12 months (−1·11 [–4·47 to 2·26]). No serious adverse events were reported. Interpretation Progressive exercise was not superior to a best practice advice session with a physiotherapist in improving shoulder pain and function. Subacromial corticosteroid injection provided no long-term benefit in patients with rotator cuff disorders

Biomarqueurs prédictifs de la maladie d'Alzheimer dans un modèle de souris (approche métabolomique par spectroscopies RMN et études comportementales)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Exact mass GC‐MS analysis: Protocol, database, advantages and application to plant metabolic profiling

International audiencePlant metabolomics has been used widely in plant physiology, in particular to analyse metabolic responses to environmental parameters. Derivatization (via trimethylsilylation and methoximation) followed by GC-MS metabolic profiling is a major technique to quantify low molecular weight, common metabolites of primary carbon, sulphur and nitrogen metabolism. There are now excellent opportunities for new generation analyses, using high resolution, exact mass GC-MS spectrometers that are progressively becoming relatively cheap. However, exact mass GC-MS analyses for routine metabolic profiling are not common, since there is no dedicated available database. Also, exact mass GC-MS is usually dedicated to structural resolution of targeted secondary metabolites. Here, we present a curated database for exact mass metabolic profiling (made of 336 analytes, 1064 characteristic exact mass fragments) focused on molecules of primary metabolism. We show advantages of exact mass analyses, in particular to resolve isotopic patterns, localise S-containing metabolites, and avoid identification errors when analytes have common nominal mass peaks in their spectrum. We provide a practical example using leaves of different Arabidopsis ecotypes and show how exact mass GC-MS analysis can be applied to plant samples and identify metabolic profiles

Non-targeted 13 C metabolite analysis demonstrates broad re-orchestration of leaf metabolism when gas exchange conditions vary

It is common practice to manipulate CO2 and O2 mole fraction during gas-exchange experiments to suppress or exacerbate photorespiration, or simply carry out CO2 response curves. In doing so, it is implicitly assumed that metabolic pathways other than carboxylation and oxygenation are altered minimally. In the past few years, targeted metabolic analyses have shown that this assumption is incorrect, with changes in the tricarboxylic acid cycle, anaplerosis (phosphoenolpyruvate carboxylation), and nitrogen or sulphur assimilation. However, this problem has never been tackled systematically using non-targeted analyses to embrace all possible affected metabolic pathways. Here, we exploited combined NMR, GC–MS, and LC–MS data and conducted non-targeted analyses on sunflower leaves sampled at different O2/ CO2 ratios in a gas exchange system. The statistical analysis of nearly 4,500 metabolic features not only confirms previous findings on anaplerosis or S assimilation, but also reveals significant changes in branched chain amino acids, phenylpropanoid metabolism, or adenosine turn-over. Noteworthy, all of these pathways involve CO2 assimilation or liberation and thus affect net CO2 exchange. We conclude that manipulating CO2 and O2 mole fraction has a broad effect on metabolism, and this must be taken into account to better understand variations in carboxylation (anaplerotic fixation) or apparent day respiration.The authors acknowledge the financial contribution of the Région Pays de la Loire and Angers Loire Métropole via the research grant Connect Talent Isoseed

Compound-Specific 14N/15N Analysis of Amino Acid Trimethylsilylated Derivatives from Plant Seed Proteins

Isotopic analyses of plant samples are now of considerable importance for food certification and plant physiology. In fact, the natural nitrogen isotope composition (δ15N) is extremely useful to examine metabolic pathways of N nutrition involving isotope fractionations. However, δ15N analysis of amino acids is not straightforward and involves specific derivatization procedures to yield volatile derivatives that can be analysed by gas chromatography coupled to isotope ratio mass spectrometry (GC-C-IRMS). Derivatizations other than trimethylsilylation are commonly used since they are believed to be more reliable and accurate. Their major drawback is that they are not associated with metabolite databases allowing identification of derivatives and by-products. Here, we revisit the potential of trimethylsilylated derivatives via concurrent analysis of δ15N and exact mass GC-MS of plant seed protein samples, allowing facile identification of derivatives using a database used for metabolomics. When multiple silylated derivatives of several amino acids are accounted for, there is a good agreement between theoretical and observed N mole fractions, and δ15N values are satisfactory, with little fractionation during derivatization. Overall, this technique may be suitable for compound-specific δ15N analysis, with pros and cons

A toolbox to explore NMR metabolomic data sets using the R environment

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Analyse métabolomique pour caractériser la régulation du métabolisme énergétique dans deux lignées de poulet sélectionnées de manière divergente sur le gras abdominal

International audienceNMR metabolomics is suitable for studying the regulation of energy metabolism on chicken lines divergent for low or high abdominal fat deposition. It is shown that plasma metabolic profiles are different in chickens fed with high and low fat diets. New information are thus obtained on circulating nutrients, which may help in elucidating key regulators associated to variations in body fat content