Sex differences in the associations between L-arginine pathway metabolites, skeletal muscle mass and function, and their responses to resistance exercise, in old age

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Objectives The current study was designed to explore the associations between L-arginine metabolites and muscle mass and function in old age, which are largely unknown. Design The study used a randomised, double-blind, placebo-controlled design. Setting The study was carried out in a laboratory setting. Participants 50 healthy older adults [median age 70 years (IQR 67-73); 27 males]. Intervention Participants undertook an 18-week resistance exercise program, and a nutritional intervention (fish oil vs. placebo). Measurements Serum homoarginine, ornithine, citrulline, asymmetric dimethylarginine (ADMA), NG-monomethyl-L-arginine (L-NMMA), and symmetric dimethylarginine (SDMA), maximal voluntary contraction (MVC) and isokinetic torque of the knee extensors at 30° s-1 (MIT), muscle cross sectional area (MCSA) and quality (MQ) were measured at baseline and after the intervention. Results No significant exercise-induced changes were observed in metabolite concentrations. There were significant sex differences in the associations between metabolites and muscle parameters. After adjusting for age, glomerular filtration rate and fish oil intervention, citrulline (P=0.002) and ornithine (P=0.022) were negatively associated with MCSA at baseline in males but not females. However, baseline citrulline was negatively correlated with exercise-induced changes in MVC (P=0.043) and MQ (P=0.026) amongst females. Furthermore, amongst males, baseline homoarginine was positively associated with exercise-induced changes in MVC (P=0.026), ADMA was negatively associated with changes in MIT (P=0.026), L-NMMA (p=0.048) and ornithine (P<0.001) were both positively associated with changes in MCSA, and ornithine was negatively associated with changes in MQ (P=0.039). Conclusion Therefore, barring citrulline, there are significant sex differences in the associations between L-arginine metabolites and muscle mass and function in healthy older adults. These metabolites might enhance sarcopenia risk stratification, and the success of exercise programs, in old age

Development of an LC–Tandem Mass Spectrometry Method for the Quantitative Analysis of Hercynine in Human Whole Blood

Given that the peculiar redox behavior of ergothioneine involves a rapid regeneration process, the measurement of its precursor and redox metabolite hercynine could be particularly useful in assessing its role in oxidative stress or other biological processes. Thus, a LC-MS/MS method for the determination of hercynine concentrations in whole blood was developed. After lysis of red blood cells by cold water, samples were filtered on micro concentrators at a controlled temperature of 4 &#176;C. The clear filtered fluid was then treated with diethylpyrocarbonate to derivatize hercynine for the analysis by LC-MS/MS. The derivatized analyte was isocratically separated as a carbethoxy derivative on a C18 column with a mobile phase of an aqueous 0.1% v/v formic acid and acetonitrile (95:5). Effluents were monitored by MRM transitions at m/z 270.28&#8594;95 and 273.21&#8594;95 for hercynine and its deuterated counterpart, respectively. No cross-talk between MRM transitions was observed and a good linearity was found within a range of 35&#8315;1120 nmol/L. The LOD and LOQ were, respectively, 10.30 and 31.21 nmol/L with an intraday and intermediate precision below 7%. The average hercynine concentration in whole blood from 30 healthy male volunteers (aged 77 &#177; 12 years) was 178.5 &#177; 118.1 nmol/L. Overall, the method is easy to perform, allowing a rapid and accurate assessment of whole blood concentrations of hercynine

Identification of the Main Intermediate Precursor of l-Ergothioneine Biosynthesis in Human Biological Specimens

A capillary electrophoresis coupled to tandem mass spectrometry (CE–MS/MS) has been used to make a qualitative determination of hercynine—the main precursor of l-ergothioneine biosynthesis—in some key human biological specimens, such as urine, whole blood, plasma, and saliva. From semiquantitative analysis results, the highest concentrations of hercynine were detected in saliva and whole blood, whereas much lower concentrations were measured in urine and plasma. Whole blood was the biological matrix with the highest concentration of l-ergothioneine followed by plasma, saliva, and urine. The antioxidant effects attributed to l-ergothioneine, along with its peculiar antioxidant mechanism, offer a possible explanation for the presence of the hercynine, as well as its concentration, in the considered biological matrices

High Dietary Taurine Reduces Apoptosis and Atherosclerosis in the Left Main Coronary Artery

We sought to determine whether taurine could specifically protect against coronary artery disease during an atherogenic diet and whether taurine affects the lipid profile, metabolites of methionine, and endothelial atherogenic systems. Rabbits were fed one of the following diets for 4 weeks: (1) control diet; (2) 0.5% cholesterol+1.0% methionine; or (3) 0.5% cholesterol+1.0% methionine+2.5% taurine. Endothelial function was examined, and the left main coronary artery atherosclerosis was quantified by stereology and semiquantitative immunohistochemistry to determine the endothelial expression of proteins related to the NO, renin-angiotensin, endoplasmic reticulum, and oxidative stress systems, as well as apoptosis. Taurine normalized hyperhomocysteinemia (P<0.05) and significantly reduced hypermethioninemia (P<0.05) but not lipidemia. The intima:media ratio was reduced by 28% (P=0.034), and atherosclerosis was reduced by 64% (P=0.012) and endothelial cell apoptosis by 30% (P<0.01). Endothelial cell CCAAT/enhancer binding protein homologous protein was normalized (P<0.05). Taurine failed to improve hyperlipidemia, endothelial function, or endothelial proteins related to the NO, renin-angiotensin, and oxidative stress systems. Taurine reduces left main coronary artery wall pathology associated with decreased plasma total homocysteine, methionine, apoptosis, and normalization of CCAAT/enhancer binding protein homologous protein. These results elucidate the antiapoptotic and antiatherogenic properties of taurine, possibly via normalization of endoplasmic reticulum stress

Laser-induced incandescence and fluorescence for in-situ characterization of soot particles and precursors in semi-technical aeronautic combustors

National audiencePhysical and chemical properties of soot emitted from airplanes are still poorly known due to the difficult access at the core of these systems, as well as the stringent conditions into or at the exhaust of the engines. It is challenging to directly measure soot particles inside aeronautic combustors due to the high pressure and limited optical access. Under these harsh combustion conditions, we try to identify the mechanisms participating in the formation of soot particles. These mechanisms are still subject to numerous questions due to the lack of experimental evidence and high demand for processing power requested by theoretical models. The solution to this problem relies on the coordinated efforts of researchers for the implementation of experimental and theoretical tools. To overcome the experimental challenges, this work focuses on the development and implementation of laser induced incandescence (LII), a technique used for the detection of soot volume fraction, as well as laser induced fluorescence (LIF), a technique used for the characterization of soot precursors

Development of coupled optical techniques for the measurements of soot and precursors in laboratory flame and aero-engine technical combustors

International audienceThis work is focused on the development of planar in-situ laser-based methods serving for the mapping of soot precursors and soot particles in hash combustion conditions. We target the soot molecular precursors and particulates because there are still unanswered questions related to the mechanisms leading to the formation of soot particles and their quantification in harsh combustion conditions. Laser-induced incandescence (LII) at 1064 nm is coupled with laserinduced fluorescence (LIF) at 532 nm to monitor soot and its precursors, respectively, on the MICADO test rig. A progressive approach is followed to implement the optical techniques, where LII/LIF is first tested and evaluated in a laminar diffusion flame, stabilized on a coflow burner at atmospheric pressure. Measurements of soot volume fraction and soot precursors are reported in combustion conditions similar to the cruise cycle in terms of total mass flow rate and pressure into the combustor

Semi–technical aero-engine combustors – a glimpse on combustion processes given by in-situ optical techniques

International audienceThe high-pressure combustion of kerosene is studied on a semi-technical aeronautic combustor equipped with a single-swirled injector using laser optical techniques. These experiments answer to nowadays milestones encountered in the aeronautic sector related to energy consumption and emissions reduction. With a focus on these objectives, our study presents a close look into the complex physicochemical processes taking place in severe combustion conditions representative of airplane engine landing-take-off (LTO) operation modes. The primary energy source (combustion) is studied with diagnostics as laser induced fluorescence/incandescence, scattering and particle image velocimetry. These techniques bring information about the precursors of soot particles, namely polycyclic aromatic hydrocarbons, soot particles, fuel spray characteristics, and velocity flow fields. Combined results are used to understand and identify the main principles governing the behavior of combustion, production of particulate and gas pollutants, as well as their radiative effects. The feasibility of selected optical techniques in these specific environments is discussed as well