Cyril Petibois

Applications of FT-IR spectrometry to plasma contents analysis and monitoring

Abstract Here, we review recent methodological developments for plasma analysis by Fourier-transform infrared (FT-IR) spectrometry to provide both a high sensitivity and a global overview of its biomolecular contents along with the variations of these ones. Transmittance FT-IR spectrometry has been used to analyze plasma micro samples (50xa0μl) using an iterative process. Results in accordance with clinical data were obtained from a single FT-IR spectrum for the following biomolecules: amino acids, fatty acids, albumin, glucose, fibrinogen, lactate, triglycerides, glycerol, urea, α 1 -antitrypsin, α 2 -macroglobulin, transferin, Apo-A 1 , Apo-B, Apo-C 3 , IgA, IgD, IgG 1 , IgG 2 , IgG 3 , IgG 4 , IgM, haptoglobin, α 1 -acid glycoprotein, cholesterol, and cholesterol esters. Therefore, as only micro samples are necessary, high frequency blood analysis become available. We also present a novel application of this method for the monitoring of inflammatory processes related to given metabolic stresses in rugby players. We show that an FT-IR spectrum constitutes a “metabolic photography” of the subject, allowing classification between metabolic groups (pathologic or others). It was used on difference spectra in order to raise “signal-to-noise” ratio by elimination of the unvarying spectral contribution. Among others, it allowed to uncover overtraining in high-level sportsmen several weeks before any physiologic or clinical symptom occurred.

Oxidative stress effects on erythrocytes determined by FT-IR spectrometry

This study was designed to evaluate changes in erythrocyte contents during endurance moderate intensity exercise, a model of physiological oxidative stress. 16 endurance-trained subjects cycled 2 h at 55% of maximal aerobic capacity and blood was collected every 15 min. Transmission FT-IR spectrometry was used to analyze separately plasma and erythrocyte content changes during oxidative stress. Erythrocyte FT-IR spectra were corrected for hemoconcentration (Hc) before spectral areas integration of main IR absorbances belonging to phospholipids [nu(as)(CH(3)), [nu(as)(CH(2)), and nu(P=O)], proteins [nu(C=O) and delta(N-H)], and lactate [nu(C-O)] were used to determine erythrocyte content changes. Changes in nu(as)(CH(2)) and nu(P=O) absorbances while nu(as)(CH(3)) remained stable showed the magnitude of free radical attacks on phospholipids bilayer. Decrease in nu(C=O) and delta(N-H) absorbances while plasma and intracellular lactate, O(2) consumption, and Hc rose were linked to hemoglobin, and possibly spectrin, denaturation. Finally, the synergistic changes found between physiological, plasmatic and erythrocyte parameters showed that FT-IR spectrometry was a sufficiently accurate and sensitive method to determine acute changes in erythrocytes during moderate, physiological, oxidative stress.

L’étiologie clinique du surentraînement au travers de l’examen sanguin : état des connaissances

Resume Propos.xa0– Le surentrainement resulte d’une balance negative entre la fatigue induite par les charges d’entrainement et les capacites de recuperation de l’organisme. Sa cause est complexe et aucun element de diagnostic clinique simple n’est disponible actuellement. Cette revue propose de faire le point sur les parametres sanguins susceptibles d’etablir l’etat de surentrainement chez le sportif. Actualites et points forts.xa0– Des alterations chroniques de la structure du myocyte peuvent entrainer une forte elevation des concentrations plasmatiques en myoglobine, en troponinexa0I et en enzyme creatine kinase, resultant d’agressions chimiques et/ou mecaniques. L’activite des radicaux libres apparait comme un bon moyen d’evaluer l’ampleur du stress metabolique subi par le muscle en activite. Au niveau du metabolisme energetique, une succession de depletions chroniques du glycogene pourrait perturber l’utilisation des acides amines et des lipides en induisant de fortes hypoglycemies d’exercice. D’une oxydation accrue de la glutamine circulante peut resulter une hyporeactivite du systeme immunitaire (baisse de la reaction aux inflammations et aux traumatismes cellulaires), conduisant a une inhibition des signaux d’alarme lies a l’entrainement trop intense. L’oxydation des acides amines ramifies pourrait aussi favoriser l’entree du tryptophane libre au niveau cerebral, un precurseur de la synthese de serotonine. Cette hormone serait a l’origine d’un etat de fatigue latente (asthenie) et d’une baisse de la sensibilite aux traumatismes musculaires et tendineux. L’anemie d’exercice pourrait aussi aggraver la situation physiologique d’un athlete deja fatigue, le predisposant au surentrainement par la moindre reactivite des proteines circulantes aux inflammations hepatiques et musculaires. Perspectives et projets.xa0– Le diagnostic precoce du surentrainement ne peut etre etabli qu’a partir d’une batterie d’analyses incluant l’ensemble de ces facteurs d’occurrences probables. Ces indicateurs demeurent neanmoins aleatoires et ne permettent pas une detection systematique des nouveaux cas. Seul un suivi biologique longitudinal semble donc susceptible d’etablir les conditions d’apparition du surentrainement pour chaque athlete.

Stress-Induced Plasma Volume Change Determined Using Plasma FT-IR Spectra

Our purpose was to determine the plasma-volume (PV) change induced by a physical stress independent of the metabolic events that may interfere with physiological fluid shifts in to and out of the intravascular space. Our methods included using 178 exercise tests of varying duration and intensity for determination of PV change during exercise. Plasma Fourier transform infrared (FT-IR) spectra were used to compare hematocrit change to the total spectral area (4000–500 cm−1) and the protein and albumin concentration changes induced by exercise. Our results showed that exercise induced a raise in protein (+10.4 ± 3.1%) and albumin (+9.8 ± 3.3%) concentrations that significantly correlated with PV change (14.1 ± 5.2% of plasma volume; P = 0.05 with protein and albumin concentration changes). However, evolution of the total spectral area obtained from rest-plasma (524 ± 21 a.u.) and exercise-plasma (611 ± 26 a.u.; +14.1 ± 4.8%) FT-IR spectra showed a higher correlation level with PV change (r = 0.98; P = 0.005; Sx/y = 1.26 a.u.). It is our conclusion that although exercise-induced changes in protein and albumin concentrations were found to correlate with PV change, the use of the total spectral area of the plasma FT-IR spectra allowed a more precise measurement of PV change.

2D-FT-IR spectrometry: a new tool for the analysis of stress-induced plasma content changes

Abstract The purpose of this study was to apply two-dimensional (2D) correlation Fourier-transform infrared (FT-IR) spectrometry to sets of plasma spectra obtained during a physical exercise. Seven male swimmers performed a maximal 400xa0m test in a 25xa0m swimming pool. On three other tests, the first 100, 200, and 300xa0m were swam on the same velocity basis of the 400xa0m test. 2D correlation spectra were obtained from blood samples taken at rest and after the 100, 200, 300, and 400xa0m tests. Exercise-induced changes in plasma concentrations and plasma spectra absorptions (νasCH3, νasCH2, νCue605O, νN–H, δNH2, and νCOO−) were compared to Z-values (correlation peak intensities) found on 2D correlation spectra. During exercise, linear changes were found for glucose, albumin (increases), triglycerides, and fatty acyl moieties (decreases), while lactate and amino-acids increased exponentially, and glycerol increased after 200xa0m (delayed). Asynchronous 2D-COS highlighted qualitative changes in fatty acid metabolism specifically related to performance (fatty acid selectivity), and allowed to distinguish the origin of urea formation between protein catabolism and amino-acid metabolism. This study has provided further evidence that 2D-FT-IR spectrometry may be used on complex biological samples, such as plasma.

FT-IR spectrometry utilization for determining changes in erythrocyte susceptibility to oxidative stress

We tested the hypothesis that FT-IR spectrometry was useful for determining oxidative stress damage on erythrocytes. Endurance-trained subjects performed a standardized endurance-training session at 75% of maximal oxygen consumption each week over 19 consecutive weeks. Capillary blood samples were taken before and after test-sessions and plasma and erythrocytes were separately analyzed using Fourier-transform infrared spectrometry. Exercise-induced change in plasma concentrations and erythrocyte IR absorptivities (vC-Hn of fatty acyl moieties, vC=O and δN-H of proteins, vP=O of phospholipids, vCOO- of amino-acids, and vC-O of lactate) were monitored and compared to training level. First training weeks induced normalization of plasma concentration changes during exercise (unchanged for glucose, moderately increased for lactate, high increases for triglycerides, glycerol, and fatty acids) while erythrocyte phospholipids alteration remained elevated (P < 0.05). Further, training reduced the exercise-induced erythrocyte lactate content increase (vC-O; P < 0.05) and phospholipids alteration (vC-Hn and vP=O; P < 0.05) during exercise. These changes paralleled the lowering of exercise-induced hemoconcentration (P < 0.05) and plasma lactate concentration increase during exercise (P < 0.05). These correlated changes between plasma and erythrocyte parameters suggest that hemoconcentration and lactate acidosis (plasmatic and intracellular) are important factors contributing to reduce erythrocyte susceptibility to oxidative stress during chronic endurance training.

Development of a specific index to detect malnutrition in athletes: Validity in weight class or intermittent fasted athletes

Fasted or weight-category athletes manage their training under strict diet conditions that could impair the stress-recovery balance and result in acute or chronic fatigue. However, to date, no validated biomarker are available to quantify this phenomena. The aim of this study was to assess the validity of a specific index combining plasma albumin and weight change to detect nutrition-related risks of fatigue increase and under-performance in athletes experiencing particular nutritional conditions. An athletes nutrition risk index (ANRI) equation, based on data from lightweight and heavyweight rowers, was developed using relationship between plasma albumin concentrations combined to weight changes with sport performance and overtraining scores and was tested by odds ratio for failure. The accuracy and sensitivity of this former specific equation was subsequently tested on runners observing the Ramadan-fasting as well as on boxers after a short weight-loss period. Independently of training and performance, lightweight rowers presented lower nutritional parameters than heavyweight (albumin: 37.4 ± 2.7 vs 39.9 ± 1.8 g·L−1, P < 0.05; weight state: 94.5 ± 1.8 vs 99.9 ± 0.9%, P < 0.01). In lightweight, ANRI was related with overtraining score (R2 = 0.21, P < 0.01), risks for failure in competition were enhanced when ANRI increased (OR:2.5, P = 0.03). Relationship of ANRI with overtraining score tended to be also significant in runners (R2 = 0.32, P = 0.06) but not in boxers (P = 0.4). Albumin concentrations combined to weight loss appeared relevant to delineate nutrition-related risks of fatigue and/or competitive failure associated with mid-term diets (about 30 days) as observed in rowers and Ramadan-fasted runners. ANRI may benefit to athletes monitoring by delineating effects of their weight loss program.