Search

BACKGROUND: Isokinetic evaluation is considered the gold standard in muscle strength measurement due to its sensitivity, intra-dynamometer reproducibility and usefulness in the injury prevention screening and follow up of subjects with musculoskeletal pathologies, neurological disease or after surgical operation. However, can one switch among different isokinetic dynamometers for the purpose of knee muscles evaluation? OBJECTIVES: To comprehensively evaluate the compatibility of the isokinetic short concentric and eccentric strength evaluation protocol and of the fatigability resistance evaluation between three different isokinetic devices. METHODS: Eighteen recreationally active men underwent three isokinetic knee testing sessions on three different isokinetic devices with 7–10 days of rest between each session. Relative (Pearson’s r product-moment correlation coefficient – PCC) and absolute (standard error of measurement – SEM, Cohen effect sizes (d) and probabilistic inferences – MBI) parameters of reproducibility were determined to assess the inter-dynamometer agreement. RESULTS: For the short concentric and eccentric strength evaluation protocol, the extensors in concentric mode and the flexors in eccentric mode can be compared (eventually with transposition formulas provided) between Biodex, Con-Trex and Cybex (almost all PCC ⩾ 0.80). The DCR could be compared between Con-Trex and Cybex and between Biodex and Cybex pairs (eventually with transposition formula provided). For the fatigability resistance evaluation protocol, the total sum can be compared for extensors (eventually with transposition formulas provided) for PM for all dynamometer pairs considered and, in the case of MW, only for Biodex and Con-Trex (PCC ⩾ 0.80). CONCLUSIONS: Only some of the parameters derived either from the short concentric and eccentric strength evaluation protocol or the fatigability resistance evaluation protocol may be interchangeable providing transposition formulas are applied. Otherwise, isokinetic findings are largely system-dependent save some specific instances.

Introduction The quantitation of glucagon remains a challenging immunoassay, mainly due to cross-reactivity. A sensitive, rapid and specific intact glucagon method is therefore necessary for quality routine analysis. A tandem mass spectrometry method to fulfill this objective is described in this work. Methods Glucagon was extracted from plasma employing a mixed-mode anion exchange solid-phase extraction. Sample stability was assessed in K2-EDTA and P800 tubes at different temperatures. We compared our method to two different immunoassays. FDA and EMA guidelines were followed for validation. An external quality control program served for comparison with other laboratories. Results Assay imprecision was below 4%. Recoveries were within 95–103%. LoQ was 8.75 pg/mL. Total analytical CV was 2.91%. Samples were found stable at 4 °C for less than 4 h. Diasource® RIA disagreed with our method. Mercodia® ELISA provided a closer agreement, also proven by external quality control samples. Conclusions A rapid and specific LC-MS/MS method for glucagon quantitation has been developed, validated and is suitable to routine care. The simplicity and the good performances in terms of time and specificity, could open the possibility to establish a standardized method for glucagon.

Objectives In-house developed liquid-chromatography mass spectrometry (LC-MS/MS) methods are used more and more frequently for the simultaneous quantification of vitamin D metabolites. Among these, 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) is of clinical interest. This study assessed the agreement of this metabolite in two validated in-house LC-MS/MS methods. Methods 24,25(OH)2D3 was measured in 20 samples from the vitamin D external quality assurance (DEQAS) program and in a mixed cohort of hospital patients samples (n=195) with the LC-MS/MS method at the Medical University of Graz (LC-MS/MS 1) and at the University of Liège (LC-MS/MS 2). Results In DEQAS samples, 24,25(OH)2D3 results with LC-MS/MS 1 had a proportional bias of 1.0% and a negative systemic difference of −0.05%. LC-MS/MS 2 also showed a proportional bias of 1.0% and the negative systemic bias was −0.22%. Comparing the EQA samples with both methods, no systemic bias was found (0.0%) and the slope was 1%. The mean difference of 195 serum sample measurements between the two LC-MS/MS methods was minimal (−0.2%). Both LC-MS/MS methods showed a constant bias of 0.31 nmol/L and a positive proportional bias of 0.90%, respectively. Conclusions This study is the first to assess the comparability of 24,25(OH)2D3 concentrations in a mixed cohort of hospitalized patients with two fully validated in-house LC-MS/MS methods. Despite different sample preparation, chromatographic separation and ionization, both methods showed high precision measurements of 24,25(OH)2D3. Furthermore, we demonstrate the improvement of accuracy and precision measurements of 24,25(OH)2D3 in serum samples and in the DEQAS program.

Background Simultaneous measurement of 25(OH)D and 24,25(OH)2D is a new tool for predicting vitamin D deficiency and allows evaluating CYP24A1 lack of function. Interpretation of 24,25(OH)2D should be performed according to 25(OH)D levels and a ratio, called the vitamin D metabolite ratio (VMR) has been proposed for such a purpose. Unfortunately, the VMR can be expressed in different ways and cannot be used if 24,25(OH)2D concentrations are undetectable. Here, we propose evaluating the enzyme activity taking into consideration the probability that a normal population presents undetectable 24,25(OH)2D concentrations according to 25(OH)D levels. We thus retrospectively measured 25(OH)D and 24,25(OH)2D in a population of 1200 young subjects to evaluate the 25(OH)D threshold above which the enzyme was induced. Methods Serum samples from 1200 infants, children, adolescent and young adults were used to simultaneously quantify 25(OH)D and 24,25(OH)2D by LCMS/MS. Results Median (interquartile range [IQR]) levels were 20.6 (14.4–27.2) ng/mL for 25(OH)D. 172 subjects (14.3%) presented 24,25(OH)2D values below the LOQ. When 25(OH)D values were 21 ng/mL. Conclusions We suggest using a statistical approach to evaluate CYP24A1 function according to 25(OH)D concentrations. Our results also show that vitamin D deficiency, as defined biochemically, could be around 20 ng/mL in infants, children, adolescent and young adults and that vitamin D deficiency could be evaluated on a more individual basis.

Introduction Determination of creatinine and estimation of Glomerular Filtration Rate (GFR) rapidly before injection of contrast media provides early detection of high-risk patients for acute kidney failure. Hence, a rapid point-of-care (POC) device (result in 30 s) allowing creatinine measurement and eGFR could be of interest. To validate this method, we considered a population referred for measuring GFR. Methods Iohexol plasma clearance was used to measure GFR. For each subject, enzymatic creatinine was quantified with two different devices: in plasma with the Roche Cobas analyzer and in capillary blood with the Nova Biomedical POC device. Both values of creatinine were used in the CKD-EPI equation for estimated glomerular filtration rate (eGFR). eGFR using POC was compared to eGFR using Cobas and to mGFR by Passing Bablok regression, calculation of bias, precision and accuracy (or concordance) within 30%. Also, we calculated the rate of discrepant staging (eGFR >60 or ≤ 60 when mGFR is actually ≤60 and > 60) with both creatinine methods. Results 120 subjects (52 ± 13 years, 49% of women) were included. Mean mGFR was 77 ± 27 mL/min/1.73m2 with 29 patients presenting mGFR 60 mL/min/1.73m2 whereas mGFR it was ≤60 and 10% (9.2%) of them would have been considered with GFR ≤60 mL/min/1.73m2 when mGFR was >60. Conclusion Creatinine measured with the POC has an acceptable performance when used with the CKD-EPI equation to estimate GFR. Its ability to detect GFR

Background Previous studies have suggested that exercising may induce cardiac damage. Galectin-3 (Gal-3) and soluble suppression of tumorigenicity 2 (ST2) are very interesting biomarkers for heart failure and myocardial fibrosis. We aimed to compare the kinetics of emerging fibrosis cardiac biomarkers as Gal-3 and ST-2 in endurance runners, and recreational runners before and after a running event represented by a marathon and an ultratrail event. Methods Blood samples were taken from 19 healthy non-elite marathon runners (42 km), 27 ultratour runners (67 km), and 14 recreational runners who represented the control group (10 km) just before the run (T0), just after (T1) and 3 h after (T2), in order to analyze Gal-3, ST2, hsTnT, NT-proBNP, CKMB and hsCRP. We compared the percentage of evolution and the slopes obtained from T0 to T1 (pT0T1) and from T1 to T2 (pT1T2), between the different groups of runners participating in three different races. Results Plasma cardiac biomarker concentrations increased significantly from baseline to immediately post-exercise and most of the time decreased over the subsequent 3-h period. For pT0T1 and pT1T2, the markers Gal-3 and ST2 showed a significant difference between types of run (p Conclusions Gal-3 and ST2 are considered as a reflection of cardiac fibrosis and remodeling. The evolution of both was different, particularly after the recovery time. ST2 values exceeding cutoff values at any time.

International audience; AbstractIntroduction/Purpose Extreme ultra-endurance races are growing in popularity, but their effects on skeletal muscles remain mostly unexplored. This longitudinal study explores physiological changes in mountain ultramarathon athletes’ quadriceps using quantitative magnetic resonance imaging (MRI) coupled with serological biomarkers. The study aimed to monitor the longitudinal effect of the race and recovery and to identify local inflammatory and metabolic muscle responses by codetection of biological markers.Methods An automatic image processing framework was designed to extract imaging-based biomarkers from quantitative MRI acquisitions of the upper legs of 20 finishers at three time points. The longitudinal effect of the race was demonstrated by analyzing the image markers with dedicated biostatistical analysis.Results Our framework allows for a reliable calculation of statistical data not only inside the whole quadriceps volume but also within each individual muscle head. Local changes in MRI parameters extracted from quantitative maps were described and found to be significantly correlated with principal serological biomarkers of interest. A decrease in the PDFF after the race and a stable paramagnetic susceptibility value were found. Pairwise post hoc tests suggested that the recovery process differs among the muscle heads.Conclusions This longitudinal study conducted during a prolonged and extreme mechanical stress showed that quantitative MRI-based markers of inflammation and metabolic response can detect local changes related to the prolonged exercise, with differentiated involvement of each head of the quadriceps muscle as expected in such eccentric load. Consistent and efficient extraction of the local biomarkers enables to highlight the interplay/interactions between blood and MRI biomarkers. This work indeed proposes an automatized analytic framework to tackle the time-consuming and mentally exhausting segmentation task of muscle heads in large multi–time-point cohorts.

Background: A key role of oxidative stress has been highlighted in the pathogenesis of COVID-19. However, little has been said about oxidative stress status (OSS) of COVID-19 patients hospitalized in intensive care unit (ICU). Material and Methods: Biomarkers of the systemic OSS included antioxidants (9 assays), trace elements (3 assays), inflammation markers (4 assays) and oxidative damage to lipids (3 assays). Results: Blood samples were drawn after 9 (7–11) and 41 (39–43) days of ICU stay, respectively in 3 and 6 patients. Vitamin C, thiol proteins, reduced glutathione, γ-tocopherol, β-carotene and PAOT® score were significantly decreased compared to laboratory reference values. Selenium concentration was at the limit of the lower reference value. By contrast, the copper/zinc ratio (as a source of oxidative stress) was higher than reference values in 55% of patients while copper was significantly correlated with lipid peroxides (r = 0.95, p &lt, 0.001). Inflammatory biomarkers (C-reactive protein and myeloperoxidase) were significantly increased when compared to normals. Conclusions: The systemic OSS was strongly altered in critically ill COVID-19 patients as evidenced by increased lipid peroxidation but also by deficits in some antioxidants (vitamin C, glutathione, thiol proteins) and trace elements (selenium).

An intralaboratory study assessing assay variability and bias for determination of serum total 25-hydroxyvitamin D [25(OH)D] was conducted by the Vitamin D Standardization Program (VDSP). Thirteen assays for serum total 25(OH)D were evaluated in a single laboratory including 11 unique immunoassays and one liquid chromatography – tandem mass spectrometry (LC-MS/MS) assay. Fifty single-donor serum samples, including eight samples with high concentrations of 25(OH)D(2) (> 30 nmol/L), were assigned target values for 25(OH)D(2) and 25(OH)D(3) using reference measurement procedures (RMP). Using four replicate measurements for each sample, the mean total percent coefficient of variation (%CV) and mean % bias from the target values were determined for each assay using the 50 single-donor samples and a 42-sample subset, which excluded 8 high 25(OH)D(2) concentration samples, and compared with VDSP performance criteria of ≤ 10% CV and ≤ ±5% mean bias. All 12 assays achieved the performance criterion for %CV, and 9 of the 12 assays were within ≤ ±5 % mean bias. The Fujirebio Inc. assay exhibited the lowest %CV and highest percentage of individual measurements within ≤ ±5% mean bias. Ten immunoassays exhibited changes in response due to the high 25(OH)D(2) samples with Abbott, Biomérieux, DiaSorin, DIAsource, and IDS-iSYS assays having the largest deviations. The Fujirebio Inc. and Beckman Coulter assays were only minimally affected by the presence of the high 25(OH)D(2) samples. Samples with high concentrations of 25(OH)D(2) provided a critical performance test for immunoassays indicating that some assays may not have equal response or recovery for 25(OH)D(2) and 25(OH)D(3).

Steroid concentrations in serum are fluctuating during pregnancy of many mammal species. The current knowledge about endocrinology of gestation is mainly based on immunoassays. However, the lack of specificity of these assays hampers the reliability of the results. In the present work, we developed and validated a methodology associating liquid chromatography (LC) and mass spectrometry (MS) to simultaneously quantify, with high specificity and accuracy, estrone-3-sulfate (E3S), progesterone (PRO), estrone (E1) and estradiol (E2) in serum of two different mammal species. The sample preparation procedure is based on a simple protein precipitation and a derivatization with dansyl chloride. After the chromatographical separation, compounds were analyzed with a triple-quadrupole mass spectrometer operating in multiple reaction monitoring. Mare and American bison serum samples were analyzed with the validated method and results were compared with concentrations measured with commercial radioimmunoassay (RIA), enzyme linked immunosorbent assay (ELISA) and chemiluminescent microparticle immunoassay (CMIA). Following these criterions: relative standard deviation15% and relative bias15%, lower limits of quantification of 0.5 ng/mL (E3S), 0.1 ng/mL (PRO) and 2 pg/mL (E1 and E2) were achieved. Most of the comparison between immunoassays and LC-MS showed poor correlation and proportional differences. Our LC-MS method is able to simultaneously quantify several steroid hormones with high specificity, accuracy and sensitivity in serum of two different mammal species. Our method constitutes a useful and performant tool for veterinary clinicians and LC-MS should thus be used to update and refine the current knowledge about the endocrinology of pregnancy in mammals.

Vitamin D status is typically assessed by the measurement of 25-hydroxyvitamin D (25(OH)D). However, in selected patient groups the sole determination of 25(OH)D has been proven insufficient for this purpose. The simultaneous measurement of additional vitamin D metabolites may provide useful information for a better evaluation of the vitamin D status. Therefore, we developed and validated a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of 25(OH)D3, 25(OH)D2, 24,25(OH)2D3 and additionally 25,26(OH)2D3, which was identified with a synthesized pure substance. Pure and deuterated substances were used to prepare calibrators and internal standards for all target metabolites. Pre-analytical sample preparation comprised protein precipitation followed by liquid-liquid-extraction and derivatization with 4-Phenyl-1,2,4-triazole-3,5-dione (PTAD) using 50 µL sample volume. Samples were analyzed on an Agilent HPLC 1260 system equipped with a silica-based Kinetex® 5 µm F5 100 A core-shell column (150 × 4.6 mm) coupled to a Sciex 4500 mass spectrometer. For all four metabolites, limit of detection (LoD) and limit of quantification (LoQ) ranged from 0.3 to 1.5 nmol/L and 1.0 to 3.1 nmol/L, respectively. Recovery varied between 76.1 % and 84.3 %. Intra- and inter-assay imprecision were

Background: The tendon is a dynamic entity that remodels permanently. Platelet-rich plasma (PRP) injection has been shown to have a beneficial effect on tendon healing after lesion in rats. Furthermore, eccentric exercise seems to improve the mechanical quality of the tendon. Hypothesis: A combination of PRP injection and eccentric training might be more effective than either treatment alone. Study Design: Controlled laboratory study. Methods: Adult male rats were anesthetized, an incision was performed in the middle of their left patellar tendon and an injection of physiological fluid (PF) or homologous PRP was randomly made at the lesion level. The rats were then divided into 2 groups: the eccentric group, undergoing eccentric training 3 times a week, and the untrained group, without any training. Thus, 4 groups were compared. After 5 weeks, the tendons were removed and their ultimate tensile strength and energy were measured. Tendons were frozen for proteomic analyses when all biomechanical tests were completed. Statistical analysis was performed with linear mixed effect models. Results: No significant difference was found between the treatments using PF injection or PRP injection alone. However, the value of the ultimate tensile force at rupture was increased by 4.5 N (108% of control, P = .006) when eccentric training was performed. An intragroup analysis revealed that eccentric training significantly improved the ultimate force values for the PRP group. Proteomic analysis revealed that eccentric training led to an increase in abundance of several cytoskeletal proteins in the PF group, while a decrease in abundance of enzymes of the glycolytic pathway occurred in the PRP-treated groups, indicating that this treatment might redirect the exercise-driven metabolic plasticity of the tendon. Conclusion: Eccentric training altered the metabolic plasticity of tendon and led to an improvement of injured tendon resistance regardless of the treatment injected (PF or PRP). Clinical Relevance: This study demonstrates the necessity of eccentric rehabilitation and training in cases of tendon lesion regardless of the treatment carried out.

Age-related cognitive decline arises from alterations in brain structure as well as in sleep-wake regulation. Here, we investigated whether preserved wake-dependent regulation of cortical function could represent a positive factor for cognitive fitness in aging. We quantified cortical excitability dynamics during prolonged wakefulness as a sensitive marker of age-related alteration in sleep-wake regulation in 60 healthy older individuals (50–69 y; 42 women). Brain structural integrity was assessed with amyloid-beta- and tau-PET, and with MRI. Participants’ cognition was investigated using an extensive neuropsychological task battery. We show that individuals with preserved wake-dependent cortical excitability dynamics exhibit better cognitive performance, particularly in the executive domain which is essential to successful cognitive aging. Critically, this association remained significant after accounting for brain structural integrity measures. Preserved dynamics of basic brain function during wakefulness could therefore be essential to cognitive fitness in aging, independently from age-related brain structural modifications that can ultimately lead to dementia., Van Egroo, Narbutas, Chylinski et al. report cortical excitability dynamics during prolonged wakefulness as a sensitive marker of age-related alterations in sleep-wake regulation in older individuals. They show that preserved wake-dependent cortical excitability dynamics are associated with better cognitive performance.

BACKGROUND: Regular physical activity is an important health factor, but intense physical stress can increase the risk of heart disease. OBJECTIVE:Our aim was to determine the potential cardiac repercussions of, and the oxidative stress resulting from a maximal eccentric isokinetic exercise and a 1-hour treadmill run at 75% ˙

Background Androstanediol glucuronide is linked to a range of disorders of peripheral androgen formation and action, such as in hirsutism and acne. Nowadays its accurate quantification is still challenging and there are just a few LC-MS/MS methods available. Besides, their reference intervals for normal European populations by LC-MS/MS, including prepubertal and pubertal children, have not been reported yet. Methods Validation of the proposed new methodology was performed at 3 levels in triplicate during 3 different days. Calibration curve concentration ranged from 0.1 to 25 µg/L. For method comparison between ELISA and the newly developed LC-MS/MS method, 43 patient samples were tested. A reference interval study was performed with 264 healthy Belgian individuals (108 male and 156 female). Results Validation of the proposed LC-MS/MS method was satisfactorily achieved, with mean imprecision values lower than 7.4%, mean recoveries within 99–108% and a limit of quantification of 0.059 µg/L. Compared to LC-MS/MS, ELISA showed a positive bias in serum samples, providing results 43% higher for the same sample. As a consequence, new reference intervals based on age and gender have been calculated. Conclusion An easy, fast and straightforward LC-MS/MS method for the determination of androstanediol glucuronide has been developed and fully validated. Besides, reference interval for normal European populations, including prepubertal and pubertal children has been established for the first time.

© 2018 Background: Aldosterone measurement is critical for diagnosis of primary aldosteronism and disorders of the renin-angiotensin system. We developed an LC-MS/MS method for plasma and urinary aldosterone and compared it to our RIA method. We present a reference interval study for a Belgian population. Methods: 68 plasma and 23 urine samples were assayed for as part of a method comparison. For the reference interval study, we enrolled 282 healthy Caucasian volunteers (114 Male: mean age 35 ± 11 y and 168 Female: mean age 42 ± 13 y). A subset of 139 healthy volunteers agreed to a 24-h urine collection. For the method validation, 5 plasma and 8 urine pools were run in triplicate and quadruplicate, respectively, on 3 different days. Results: Between-run imprecision (CV) was 2.8–5.1% for plasma and 4.5–8.6% for urine, except at the low urine concentration of 2.99 nmol/L where a CV of 15.4% was observed. The limit of quantitation was 0.04 nmol/L for plasma and 6.65 nmol/L for urine. Recoveries, based on spiking experiments into natural matrix, did not differ significantly from 100%. Regression comparisons showed that, on average, RIA generated results were 59% and 11% higher than LC-MS/MS for plasma and urine, respectively. The MS reference interval we propose for plasma aldosterone is 0.07 nmol/L–0.73 nmol/L for women and 0.04 nmol/L–0.41 nmol/L for men. No gender difference was observed for urine aldosterone. The reference interval was determined to be

Background Burn patients are at risk of vitamin D (VD) deficiency and may benefit from its pleiotropic effects as soon as acute phase. Aim of this observational study was to assess effects of a cholecalciferol (VD3) bolus on VD status in adult burn patients (Group B, GB) after admission, compared to healthy subjects (Group H, GH). Methods Both groups received an oral dose of 100,000 IU VD3. Blood samples were collected before (D0) and 7 days (D7) after bolus to measure 250H-D, 1,25(OH)2-D, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23). Albumin (ALB) and VD binding protein (DBP) were measured and used to calculate free 25OH-D level. Data were expressed as median (min–max) or proportions. Results A total of 49 subjects were included: 29 in GH and 20 in GB. At D0, prevalence of VD deficiency was higher in GB: 25OH-D was 21.5 (10.1–46.3) ng/ml in GH vs 11 (1.8–31.4) ng/ml in GB. DBP and ALB were lower in GB. At D7, DBP was stable in both groups while ALB decreased in GB. 25OH-D increased by 66.6 (13.5–260.3)% in GH. In GB, changes in 25OH-D extended from −36.7% to 333.3% with a median increase of 33.1%. Similar changes were observed in each group for free 25OH-D. High FGF23 levels were observed in GB. Conclusions This study highlighted the differences in VD status and in response to a high dose VD3 in burn patients when compared to healthy patients. Pitfalls in VD status assessment are numerous during acute burn care: 25OH-D measurement needs cautious interpretation and interest of free 25OH-D is still questionable. They should not prevent burn patients to receive VD supplements during acute care. Higher doses than general recommendations should probably be considered.

Rugby is a sport that is growing in popularity. A contact sport par excellence, it causes a significant number of injuries. In Rugby Union, there are 30 to 91 injuries per 1000 match hours. This epidemiological review of injuries incurred by rugby players mentions the position and type of injuries, the causes, time during the match and season in which they occur and the players’ positions as well as the length of players’ absences following the injury.

A 50+ SPF sunscreen decreased significantly cutaneous vitamin D production following a single narrow-band (nb)UVB exposure, independently from the body surface area exposed. In contrast, the circulating 25(OH)D3 levels were only minimally affected. It is probable that another endogenous source of precursors is selected when skin-originated precursors are lacking. Sunscreen use, highly advocated for preventing cutaneous carcinogenesis, is potentially leading to an aggravation of vitamin D deficiency with its consequences on bone health. The effect of sunscreens on circulating vitamin D levels remains debated. This study investigated the effect of sunscreen on cutaneous vitamin D production and circulating 25(OH)D3 levels, according to different body surface areas (BSA). Vitamin D and 25(OH)D3 levels were measured in four groups exposed to a single nbUVB exposure on 9% (group I: head and hands), 23% (group II: head, hands and arms), 50% (group III: head, hands, arms and legs) and 96% (group IV: total body) of the body surface without and with a 50+ sun protection factor sunscreen. Sunscreen use decreased by 83, 88.3, 75.7 and 92.5% the cutaneous vitamin D production in groups I to IV, respectively, but only by 13.2, 10.5, 7.7 and 10.4% the values of circulating 25(OH)D3, correspondingly. Although a 50+ sunscreen decreases significantly cutaneous vitamin D production following a single nbUVB exposure, and independently from the BSA, the circulating 25(OH)D3 levels were only minimally affected. This could be explained by a switch to another endogenous source of precursors. Short-term sunscreen use probably does not affect circulating vitamin D levels and hence does not increase the risk for osteoporosis. The effect of long-term sunscreen use remains however to be determined.

Background:We provide a clinical and analytical evaluation of the reformulated version of the Abbott Architect 25-hydroxyvitamin D assay. We compared this assay with three commercial automated immunoassays and against a VDSP-traceable liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in six different populations. We also supplemented 40 healthy volunteers with either 600,000 IU of vitamin D2 or 100,000 of vitamin D3 to evaluate the performance of the immunoassays vs. the LC-MS/MS.Methods:Precision and limit of quantification were assessed, 25(OH)D2 and C3-epimer recovery were calculated. Two hundred and forty samples obtained in healthy Caucasians and Africans, osteoporotic, hemodialyzed and intensive care patients and 3rd trimester pregnant women were analyzed by all methods. Correlation was studied using Passing-Bablok and Bland-Altman analysis. Concordance correlation coefficient (CCC) was calculated to evaluate agreement between immunoassays and LC-MS/MS. We verified if patients were homogeneously classified with the immunoassays when they took vitamin D2 or vitamin D3 after 1, 7 and 28 days.Results:We observed excellent analytical features and showed a very good correlation to the LC-MS/MS results in the overall population. Compared to the other immunoassays, concordance of the new Abbott assay with the LC-MS/MS was at least similar, and often better in diseased populations. Althought the cross-reactivity with 25(OH)D2 was not of 100%, there was no significant difference in the classifications of the patients, either supplemented with D2 or D3 or after 7 or 28 days.Conclusions:This modified version of the Abbott Architect assay is clearly improved compared to the previous one and presents a better agreement with the LC-MS/MS.

Background Interpretation of 25OH-D measurement during critical care (CC) may be problematic due to variations of binding protein concentrations (albumin, ALB, and vitamin D binding protein, VDBP). Determination of free 25OH-D concentration may thus be relevant in CC patients. The aim of this observational study was to evaluate effects of an acute hemodilution on vitamin D (VD) status. Methods Blood samples were obtained before (T1) and after a crystalloid load (T2) administered at anesthesia induction for minor surgery. 25OH-D was measured with LC–MS/MS and with 3 immunoassays (IA): DiaSorin Liaison, IDS iSYS and bioMerieux Vidas. VDBP was measured with the R&D Elisa and ALB on Cobas. Free 25OH-D was calculated using published formula. Accuracy of each 25OH-D IA was calculated as the percentage of IA values within 20% of their respective LC–MS/MS values. Performances of the three AI were compared with LC–MC/MS using Bland–Altman analysis. Results Twenty adults were included. Compared to T1 values, VDBP, ALB and LC–MS/MS values decreased in parallel by a mean of 23% at T2. IA values decreased less significantly (12, 14 and 15% for Liaison, iSYS and Vidas, respectively). IA-based calculated free 25OH-D significantly increased after dilution, while LC–MS/MS-based free values remained stable. At T1 and T2, bias were demonstrable for all IA. After hemodilution, bias would lead to overestimation for the three IA. Accuracy of IA decreased after dilution. Conclusions Due to matrix effects, compared to LC–MS/MS, IA results were impacted by hemodilution. In CC patients, LC–MS/MS seems to be the best option to measure 25OH-D. Specific LC–MS/MS method should be developed to measure free 25OH-D.

Background: Cardiac biomarkers elevations have been described after running exercise. Objective of our study was to check cardiac biomarker dynamics in well trained athletes and untrained middle aged apparently healthy men and to highlight the impact on the lab results interpretation in emergency department. Methods: Cardiac biomarkers for ischemic condition, cardiac stretch and fibrotic processes were tested in different type of runners before, directly after and 3 hours after running. Markers for inflammation, muscle disease and renal function were also measured. Results: Cardiac biomarker levels between groups were not statistically different in the pre-exercise samples for natriuretic peptides [B-type natriuretic peptide (BNP), N-terminal Pro BNP (NT-ProBNP)] and galectin-3 (Gal-3), only Troponin I levels were higher. Directly after exercise, all cardiac biomarker levels were higher compared to the baseline, Gal-3 and BNP levels decreased 3 hours after completion of the run. Troponin values continued to increase with highest levels 3 hours after exercise. Troponin T, NT-Pro-BNP and Gal-3 also showed significant correlation to markers of inflammation, fibrosis and renal function. Conclusions: Exercises of different intensity can be associated with biochemical abnormalities and long-term consequences are unknown. In chest pain patients presenting to the emergency department possible impact of exercise on test results, especially Troponin, should be checked.

Introduction: A fatty acid (FA) is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Recently, the role of FA and particularly omega-3 and -6 has emerged as cardiovascular risk factor in the literature. The aim of our study was to establish reference values for these FA and to compare them with data obtained in a population of acute myocardial infarction (AMI) patients. Materials and methods: Hundred thirty five healthy subjects (59.38 ± 27.12 yo, 75 men) were selected as reference population. We also evaluated FA in thirty three patients (55 ± 9 yo, 23 men) admitted in the Emergency Department of our Institution for AMI. The fasting whole blood was drawn in vacutainer containing EDTA. Before analysis, samples were washed and transmethylated. We performed the quantification of different FA by gas chromatography associated with flame ionization detector (GCFID). Results: We obtained results in control healthy patients to be used as reference values. In the AMI group, levels of omega-6 were significantly higher (p 0.05) for C18:2n6 and C18:3n6 than the reference population and omega-3 values were significantly lower (p 0.01) compared to reference value for C22:6n3. The omega-3 index was lower and the ratio omega-6/omega-3 was higher in AMI group compared to reference values. Conclusions: We have established reference value for FA and have compared these values with the results obtained in AMI population. FA determination is a new tool we are able to use and to process in our laboratory which can help the clinician to screen patients with the highest cardiovascular risks because of the implication of FA in the etiopathogeny of atherosclerosis.

Background Chronic kidney disease (CKD) is diagnosed and explored through the determination of the glomerular filtration rate (GFR). Our goal was to develop a simple LC-MS method for the determination in serum of 2 popular GFR markers, contrast agents iohexol and iothalamate, for routine use and comparison studies between the two markers. A similar contrast agent, ioversol, was used as an internal standard and the method underwent a rigorous validation protocol based on β-expectation tolerance intervals. Methods We adapted the HPLC-UV method from Cavalier et al. to our LC-MS system. Data treatment for the validation was performed using Multiquant 3.0 (Sciex, Framingham, MA, USA) and e.noval 3.0 software (Arlenda, Liege, Belgium). Results According to the validation results our method will give accurate and reliable results for concentrations ranging from 6.8 to 250 μg/ml for iohexol and 6.15 μg/ml to 250 μg/ml for iothalamate. In our practice these intervals are sufficient to determine both compounds in most patient samples. Samples with higher detected concentrations can always be diluted into range. Conclusion With its internal standard and extensive validation, our method is now ready for routine and clinical research use.

International audience; Background: Pioneer studies demonstrate the impact of extreme sport load on the human brain, leading to threatening conditions for athlete's health such as cerebral edema. The investigation of brain water diffusivity, allowing the measurement of the intercellular water and the assessment of cerebral edema, can give a great contribution to the investigation of the effects of extreme sports on the brain. We therefore assessed the effect of supra-physiological effort (extreme distance and elevation changes) in mountain ultra-marathons (MUMs) athletes combining for the first time brain magnetic resonance imaging (MRI) and blood parameters.Methods:This longitudinal study included 19 volunteers (44.2 ± 9.5 years) finishing a MUM (330 km, elevation + 24000 m). Quantitative measurements of brain diffusion-weighted images (DWI) were performed at 3 time-points: Before the race, upon arrival and after 48 h. Multiple blood biomarkers were simultaneously investigated. Data analyses included brain apparent diffusion coefficient (ADC) and physiological data comparisons between three time-points.Results:The whole brain ADC significantly increased from baseline to arrival (p = 0.005) and then significantly decreased at recovery (p = 0.005) to lower values than at baseline (p = 0.005). While sodium, potassium, calcium, and chloride as well as hematocrit (HCT) changed over time, the serum osmolality remained constant. Significant correlations were found between whole brain ADC changes and osmolality (p = 0.01), cholesterol (p = 0.009), c-reactive protein (p = 0.04), sodium (p = 0.01), and chloride (p = 0.002) plasma level variations.Conclusions:These results suggest the relative increase of the inter-cellular volume upon arrival, and subsequently its reduction to lower values than at baseline, indicating that even after 48 h the brain has not fully recovered to its equilibrium state. Even though serum electrolytes may only indirectly indicate modifications at the brain level due to the blood brain barrier, the results concerning osmolality suggest that body water might directly influence the change in cerebral ADC. These findings establish therefore a direct link between general brain inter-cellular water content and physiological biomarkers modifications produced by extreme sport.

Platelet-rich plasma (PRP) contains growth factors involved in the tissular healing process. The aim of the study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. In conclusion, an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance.

The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favorable, the biomechanical changes to the tissue are not yet clear. Even if the mechanotransduction theory is commonly accepted, the physiology of tendons is not clearly understood. We aimed to better define the biomechanical and histological changes that affect healthy tendon after eccentric and concentric training. This study compared the effects of two methods of training (eccentric [E] training and concentric [C] training) with untrained (U) rats. The animals were trained over a period of 5 weeks. The tricipital, patellar, and Achilles tendons were removed, measured and a tensile test until failure was performed. A histological analysis (hematoxylin and eosin and Masson's trichrome stains) was also realized. There was a significant increase in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-sectional area than the E- and C-trained groups, but none was constated between E and C groups. No significant difference was observed for the mechanical stress between the three groups for all three tendons. Histological studies demonstrated the development of a greater number of blood vessels and a larger quantity of collagen in the E group. The mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the healing of tendon.

Objective: The present review was performed in order to bring together the current knowledge about the impact of intense physical exercise on cardiovascular function, especially on plasma levels of cardiovascular risk markers such as cardiac troponin T (cTnT), myeloperoxidase (MPO), amino-terminal pro-brain natriuretic peptide (NT-proBNP), C-reactive protein (CRP) and oxidized low-density lipoprotein (oxLDL). Methods: Data were collected using the PubMed database. The articles were chosen for their relevance and importance in the area of interest. Results: The literature describes numerous examples where physical exercise induces plasma variation for the markers studied. Intense physical effort increases the levels of cTnT, MPO and NT proBNP, whereas CRP and oxLDL levels tend to be decreased with regular sport activities. Conclusions: The present literature investigation confirms the fact that intense physical exercise has an impact on the plasma variations of the five cardiovascular risk markers studied. However, practising regular exercise remains one of the first strategies for the prevention of cardiovascular disorders.

Background Mitral regurgitation is a frequent valvular heart disease affecting around 2.5 % of the population with prevalence directly related to aging. Degeneration of mitral valve is broadly considered as a passive ongoing pathophysiological process and little is known about its physiological deregulation. The purpose of this study was to highlight new biomarkers of mitral regurgitation in order to decipher the underlying pathological mechanism as well as to allow the diagnosis and the monitoring of the disease. Results Modulation of various blood proteins expression was examined in patients suffering from different grades of mitral regurgitation (mild, moderate and severe) compared to healthy controls. To this end, several routine clinical assays and the multi analyte profile technology targeting 184 proteins were used. High-density lipoprotein, apolipoprotein-A1, haptoglobin and haptoglobin-α2 chain levels significantly decreased proportionally to the degree of mitral regurgitation when compared to controls. High-density lipoprotein and apolipoprotein-A1 levels were associated with effective regurgitant orifice area and regurgitant volume. Apolipoprotein-A1 was an independent predictor of severe mitral regurgitation. Moreover, with ordinal logistic regression, apolipoprotein-A1 remained the only independent factor associated with mitral regurgitation. In addition, myxomatous mitral valves were studied by immunocytochemistry. We observed an increase of LC3, the marker of autophagy, in myxomatous mitral valves compared with healthy mitral valves. Conclusion These potential biomarkers of mitral regurgitation highlighted different cellular processes that could be modified in myxomatous degenerescence: reverse cholesterol transport, antioxidant properties and autophagy. Electronic supplementary material The online version of this article (doi:10.1186/s12014-015-9097-2) contains supplementary material, which is available to authorized users.

International audience; B-type natriuretic peptide (BNP) is often used as a complementary finding in the diagnostic work-up of patients with aortic stenosis (AS). Whether soluble ST2, a new biomarker of cardiac stretch, is associated with symptomatic status and outcome in asymptomatic AS is unknown. sST2 and BNP levels were measured in 86 patients (74±13 years; 59 asymptomatic, 69%) with AS (23 ng/mL, AUC = 0.68, p

Background While a moderate exercise benefits on the cardiovascular system, consequences of a supraphysiological effort are not yet clear. Objective The aim of our study was to evaluate the consequences of an ultra-marathon on cardiac and muscles markers (CK, myoglobin, hsTnT, NT-proBNP, copeptin, H-FABP) but also markers of inflammation CRP DFO, GB) and of renal function (urinary NGAL and plasma and urinary creatinine). This project also studied the evolution of new cardiac fibrosis biomarkers: ST2 and Gal-3. Design Longitudinal, cohort study. Setting The Tor des Geants (TdG), a 330 km long ultra distance trail running, with +24,000 m elevation changes in the Valley of Aosta (Italy), is considered as one of the most difficult mountain marathon race in the world. The maximum time allowed to complete the race is 150 h. Patients (or Participants) 51 participants attending the TdG have been followed and the study was conducted on 33 subjects having reached at least half of the race (148.7 km). Interventions (or Assessment of Risk Factors) Repeated blood and urine samples collection were carried out at four key time points: before, during (mid-point) and after the race (less than 1 h) and 3 days after the end of the race. Main Outcome Measurements Biological samples were collected at these four different times. Several biomarkers were assayed on different analyzers such COBAS®, KRYPTOR®, VIDAS® and ETIMAX®, meanwhile, the ST2 and Gal-3 were measured manually. Results During the TdG, the plasma levels of cardiac markers, muscle and inflammation have increased significantly to halfway. Meanwhile, the markers of renal function have only slightly varied, excepting plasma creatinine. Conclusions The study suggests that there is no permanent structural damage at the myocardium level. However, the low pace adopted by the tired runners caused an inflammatory response as well as muscle damage less important than a shorter race.

Background: The study was conducted to evaluate the analytical and clinical performance of the VIDAS (R) 25-OH Vitamin D Total assay. The clinical performance of the assay was compared with four other immunoassays against the results of two different liquid chromatography/mass spectrometry methods (LC-MS/MS)-standardized to NIST reference materials. Methods: VIDAS (R) 25-OH Vitamin D Total assay precision, linearity, detection limits and sample matrix comparison were assessed following CLSI guidelines. For method comparison, a total of 150 serum samples ranging from 7 to 92 ng/mL were analyzed by all the methods. Correlation was studied using Passing-Bablok regression and Bland-Altman analysis. The concordance correlation coefficient (CCC) was calculated to evaluate agreement between immunoassays and the reference LC-MS/MS method. In addition, samples containing endogenous 25(OH) D 2 were used to assess each immunoassay's ability to detect this analyte. Pregnancy and hemodialysis samples were used to the study the effect of vitamin D binding protein (DBP) concentration over VIDAS (R) assay performance. Results: The VIDAS (R) 25-OH Vitamin D Total assay showed excellent correlation to the LC-MS/MS results (y = 1.01x+0.22 ng/mL, r=0.93), as obtained from two different sites and distinct LC-MS/MS methods. The limit of quantification was determined at 8.1 ng/mL. Cross-reactivity for 25(OH) D 2 was over 80%. At concentrations of 10.5, 26 and 65.1 ng/mL, within-run CVs were 7.9%, 3.6% and 1.7%, while total CVs (between runs, calibrations, lots and instruments) were 16.0%, 4.5% and 2.8%. The VIDAS (R) performance was not influenced by altered DBP levels, though under-recovery of 25(OH) D as compared to LC-MS/MS was observed for hemodialysis samples. Conclusions: The VIDAS (R) 25-OH Vitamin D Total assay is therefore considered suitable for assessment of vitamin D status in clinical routine.

Summary Introduction Cardiopathies are the world's leading cause of mortality and morbidity. Although rare, cardiovascular accidents can occur during intense and infrequent sporting activity, particularly among those who are unaware of their heart condition. The development of cardiospecific biochemical markers has led to a reconsideration of the role of biology in the diagnosis of cardiovascular illnesses. The aim of this study therefore was, through the use of cardiac biomarker assays, to highlight the impact of sustained physical effort in the form of intense and prolonged concentric isokinetic exercise and to research potential cardiovascular risks. Materials and methods Eighteen subjects participated in a maximal concentric isokinetic exercise involving 30 knee flexion–extensions for each leg. Five blood tests were taken to study the kinetics of the cardiac biomarkers. Haemodynamic parameters were measured continuously using a Portapres, and respiratory parameters were measured using a Sensormedics Vmax 29C. Results The results showed significant increases in the creatine kinase, myoglobin, homocysteine and haemoglobin cardiac markers. Evolutionary trends were also observed for the following biomarkers: NT-proBNP, myeloperoxydase and C-reactive protein. All the physiological parameters measured presented statistically significant changes. Conclusion Isokinetic effort leads to the release of cardiac markers in the blood, but these do not exceed the reference values in healthy subjects. Maximal concentric isokinetic exercise does not, therefore, lead to an increased risk of cardiovascular pathologies.

Standardization of immunoassays for 25(OH)-vitamin D determination is a major problem in clinical practice. A worldwide standardization program has started to address this and will reduce the bias observed between immunoassays. We aimed to calibrate 5 immunoassays on a LC-MS/MS traceable to the SRM 2972 and the ID-LC-MS/MS 25(OH)D Reference Method Procedure to see if the re-standardization would be efficient in a population of 3rd trimester pregnant women (PW), hemodialysis (HD) and osteoporosis (OP) patient.184 serum samples (25(OH)D: 8.4-87 ng/ml) were selected to calibrate the immunoassays (Abbott-Architect, Roche-Elecsys, DiaSorin-Liaison, Siemens-Centaur and IDS-iSYS). Chromsystems MassChrom method was used as the referenced. Serum obtained in 34 PW, 25 HD and 34 OP patients were used as comparatives.After adjusting to LC-MS/MS, immunoassays had regression slopes nearly identical to 1.0 with intercepts0.5 ng/ml. However, in special populations, a systematic bias was still observed, except for iSYS.Re-standardization of 25(OH)D immunoassay will globally improve the differences. However, patients with a different serum matrix will still present significantly different results when they will be run with different methods. For those patients, the LC-MS/MS method seems to be the method of choice, even if some immunoassays are less influenced than others.

Platelet-rich plasma (PRP) contains a large number of growth factors, which may enhance tendon healing processes. Local injection of PRP represents a relatively new treatment for tendinopathies. To date, no side effects have been reported after injection of PRP to treat tendinopathy. We report a case of exuberant inflammatory reaction after 1 injection of PRP to treat jumper's knee in a 35-year-old male type 1 diabetic patient. Injections of PRP should be proposed only after careful consideration in cases of patients with morbidity risks linked to insulin-dependent diabetes.

Background: The study was conducted to evaluate the technical and clinical performance of the VITROS® Immunodiagnostic Products 25-OH Vitamin D Total Assay, and compare it with the performance of five marketed automated assays and a liquid chromatography/mass spectrometry reference method (LC-MS/MS). Methods: Three hundred patient serum samples were used to compare the correlation of the VITROS® 25-OH Vitamin D Total Assay with both the other immunoassays and the LC-MS/MS method, using Passing-Bablok regression and Bland-Altman analyses. Concordance of the diagnosis of vitamin D status was calculated to test the agreement between the different assays. In addition, samples containing vitamin D2 were used to test the assay’s ability to detect the D2 form of the vitamin. Results and conclusions: These results from the VITROS® 25-OH Vitamin D Total Assay generally correlated well with those from most of the marketed immunoassays. Cross-reactivity of the D2 form was calculated as being close to 100%. Additionally, we found substantial variability in performance amongst the various assays, which suggests the need for optimisation and recalibration of commercial methods.