Nonlinear ultrasound monitoring of fatigue microdamage accumulation in cortical bone

Accumulation of bone micro-damage is suspected to lead to severe impairment of mechanical properties with an increase in skeletal fragility and fracture risk. The objective of the study was to evaluate the potential of Nonlinear Resonant Ultrasound Spectroscopy (NRUS) for measuring micro-damage accumulation in cortical bone using four-point bending cycling fatigue. Sixteen human cortical bone specimens were machined as parallelepiped beams. Damage progression was controlled by measuring the linear elastic beam theory modulus (E LEBT ), known to reflect microdamage accumulation. Before and between each damage step, the nonlinear ultrasonic elastic coefficient was measured by NRUS. At the end of each cycling fatigue, a subset of bone samples was measured by μCT at the European Synchrotron Radiation Facility. Results showing a progressive increase of nonlinear ultrasonic elastic coefficient along fatigue cycling suggest that NRUS measurements are sensitive to micro-damage accumulation. The results mentioned above were validated using synchrotron radiation μCT. The variation of elastic nonlinearity was found to be significantly correlated to the variation of number density of small microcracks which almost doubled in damaged regionsThis research was supported by the Agence Nationale pour la Recherche (ANR), France (Grant BONUS_07BLAN0197

Resuming Training in High-Level Athletes After Mild COVID-19 Infection: A Multicenter Prospective Study (ASCCOVID-19)

BACKGROUND: There is a paucity of data on cardiovascular sequelae of asymptomatic/mildly symptomatic SARS-Cov-2 infections (COVID). OBJECTIVES: The aim of this prospective study was to characterize the cardiovascular sequelae of asymptomatic/mildly symptomatic COVID-19 among high/elite-level athletes. METHODS: 950 athletes (779 professional French National Rugby League (F-NRL) players; 171 student athletes) were included. SARS-Cov-2 testing was performed at inclusion, and F-NRL athletes were intensely followed-up for incident COVID-19. Athletes underwent ECG and biomarker profiling (D-Dimer, troponin, C-reactive protein). COVID(+) athletes underwent additional exercise testing, echocardiography and cardiac magnetic resonance imaging (CMR). RESULTS: 285/950 athletes (30.0%) had mild/asymptomatic COVID-19 [79 (8.3%) at inclusion (COVID(+)(prevalent)); 206 (28.3%) during follow-up (COVID(+)(incident))]. 2.6% COVID(+) athletes had abnormal ECGs, while 0.4% had an abnormal echocardiogram. During stress testing (following 7-day rest), COVID(+) athletes had a functional capacity of 12.8 ± 2.7 METS with only stress-induced premature ventricular ectopy in 10 (4.3%). Prevalence of CMR scar was comparable between COVID(+) athletes and controls [COVID(+) vs. COVID(-); 1/102 (1.0%) vs 1/28 (3.6%)]. During 289 ± 56 days follow-up, one athlete had ventricular tachycardia, with no obvious link with a SARS-CoV-2 infection. The proportion with troponin I and CRP values above the upper-limit threshold was comparable between pre- and post-infection (5.9% vs 5.9%, and 5.6% vs 8.7%, respectively). The proportion with D-Dimer values above the upper-limit threshold increased when comparing pre- and post-infection (7.9% vs 17.3%, P = 0.01). CONCLUSION: The absence of cardiac sequelae in pauci/asymptomatic COVID(+) athletes is reassuring and argues against the need for systematic cardiac assessment prior to resumption of training (clinicaltrials.gov; NCT04936503).L'Institut de Rythmologie et modélisation Cardiaqu

Fibrillation et flutter auriculaire du jeune sportif (à propos de 21 cas)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-Bib. Serv.Santé Armées (751055204) / SudocSudocFranceF

Nonlinear resonant ultrasound spectroscopy is sensitive to the level of cortical bone damage

International audienceThe objective of the study was to evaluate the sensitivity of nonlinear resonant ultrasound spectroscopy (NRUS) measurements to the accumulation of damage in cortical bone by fatigue or by controlled crack propagation. Two groups of human cortical bone specimens were prepared from the femoral mid-diaphysis. The specimens from the first group were taken through a progressive fatigue protocol consisting of four steps of cyclic four-point bending. The specimens from the second group were taken through a toughness protocol consisting of initiation and controlled propagation of a stable crack induced by 4-point bending mechanical loading. Our results evidenced a progressive increase of the normalized nonlinear elastic parameter during fatigue testing or during toughness experiments. While in specimens subjected to mechanical fatigue cycling the relative variation of nonlinear elasticity was significantly related to the relative variation of the number density of small cracks assessed with micro-computed tomography, in crack propagation experiments a significant relationship was found between the level of nonlinearity and total crack length. These results strongly suggest that NRUS measurements are sensitive to damage accumulation and can be used as a marker of bone damage

Nonlinear ultrasound monitoring of single crack propagation in cortical bone

Accumulation of bone microdamage is suspected to lead to severe impairment of mechanical properties with an increase in skeletal fragility and fracture risk. The objective of the study was to evaluate the sensitivity of nonlinear resonant ultrasound spectroscopy (NRUS) measurements to the propagation in cortical bone of a single microcrack induced by 4-point bending mechanical loading. Twelve human cortical bone specimens were machined as parallelepiped beams (50*2*2mm) to unambiguously identify resonant modes for NRUS measurements. A central notch of 600{lower case mu}m was made to control crack initiation and propagation during four-point bending loading. The nonlinear hysteretic elastic coefficient ({lower case alpha} f ) was derived from NRUS measurements achieved in dry and wet conditions. Each bone specimen was probed by a swept-sine around its first compression mode, applying progressively increasing drive levels. Moreover, the buried crack length was assessed by synchrotron radiation micro-computed tomography with a spatial resolution of 1.4{lower case mu}m. Despite between-sample variability, {lower case alpha} f increased significantly in the damaged state (44.9±85.4) compared to the initial value (5.5±1.5) in the control undamaged state. Crack length was significantly correlated to the nonlinear elastic parameter {lower case alpha} f (r ² =0.78, p<0.001). These results suggest that NRUS is sensitive to damage accumulation and can be used as a marker of bone damage

Response to Letter Regarding Article, "Recognition and Significance of Pathological T-Wave Inversions in Athletes"

International audienceno abstrac

Recognition and Significance of Pathological T-Wave Inversions in Athletes

Background-Pathological T-wave inversion (PTWI) is rarely observed on the ECG of healthy athletes, whereas it is common in patients with certain cardiac diseases. All ECG interpretation guidelines for use within athletes state that PTWI (except in leads aVR, III and V1 and in V1-V4 when preceded by domed ST segment in asymptomatic Afro-Caribbean athletes only) cannot be considered a physiological adaptation. The aims of the present study were to prospectively determine the prevalence of cardiac pathology in athletes presenting with PTWI, and to examine the efficacy of cardiac magnetic resonance in the work-up battery of further examinations. Methods and Results-Athletes presenting with PTWI (n=155) were investigated with clinical examination, ECG, echocardiography, exercise testing, 24h Holter ECG, and cardiac magnetic resonance. Cardiac disease was established in 44.5% of athletes, with hypertrophic cardiomyopathy (81%) the most common pathology. Echocardiography was abnormal in 53.6% of positive cases, and cardiac magnetic resonance identified a further 24 athletes with disease. Five athletes (7.2%) considered normal on initial presentation subsequently expressed pathology during follow-up. Familial history of sudden cardiac death and ST-segment depression associated with PTWI were predictive of cardiac disease. Conclusions-PTWI should be considered pathological in all cases until proven otherwise, because it was associated with cardiac pathology in 45% of athletes. Despite echocardiography identifying pathology in half of these cases, cardiac magnetic resonance must be considered routine in athletes presenting with PTWI with normal echocardiography. Although exclusion from competitive sport is not warranted in the presence of normal secondary examinations, annual follow-up is essential to ascertain possible disease expression.</p

The ThomX ICS source

International audienceThomX is a new generation Compact Compton Source. It is currently commissioned by and at the IJCLab (Laboratoire de physique des 2 infinis - Irène Joliot-Curie (UMR9012)) at Orsay. The first beam is expected at the begining of 2021. The aim of ThomX is to demonstrate the characteristics of an intense and Compact (lab-size) X-ray source based on Compton Scattering. The performances are mostly driven by the laser optical system which is above the state of the art of stored laser power. Proof of principle of various X-ray techniques will be performed thanks to the versatile ThomX beamline. Firstly, this article presents the machine description. Secondly, the issues and limits of the laser system are discussed. Then, the ThomX beamline is described and the machine status conclude the ThomX presentation. Finally, the expected performances for the next years and the possible experiments that can be made with this new machine are detailed

QUBIC:Exploring the primordial universe with the Q&amp;U bolometric interferometer

In this paper we describe QUBIC, an experiment that will observe the polarized microwave sky with a novel approach, which combines the sensitivity of state-of-the art bolometric detectors with the systematic effects control typical of interferometers. QUBIC unique features are the so-called "self-calibration", a technique that allows us to clean the measured data from instrumental effects, and its spectral imaging power, i.e. the ability to separate the signal in various sub-bands within each frequency band. QUBIC will observe the sky in two main frequency bands: 150 GHz and 220 GHz. A technological demonstrator is currently under testing and will be deployed in Argentina during 2019, while the final instrument is expected to be installed during 2020.Comment: Proceedings of the 2018 ICNFP conference, Crete. Published by Universe arXiv admin note: text overlap with arXiv:1801.0373