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This study aimed to characterize peak exercise cardiac function and thigh muscle fatty infiltration and their relationships with VO 2 peak among anthracycline-treated breast cancer survivors (BCS). BCS who received anthracycline chemotherapy ~ 1 year earlier (n = 16) and matched controls (matched-CON, n = 16) were enrolled. Resting and peak exercise cardiac function, myocardial T 1 mapping (marker of fibrosis), and thigh muscle fat infiltration were assessed by magnetic resonance imaging, and VO 2 peak by cycle test. Compared to matched-CON, BCS had lower peak SV (64 ± 9 vs 57 ± 10 mL/m 2 , p = 0.038), GLS (− 30.4 ± 2.2 vs − 28.0 ± 2.5%, p = 0.008), and arteriovenous oxygen difference (16.4 ± 3.6 vs 15.2 ± 3.9 mL/100 mL, p = 0.054). Mediation analysis showed: (1) greater myocardial T 1 time (fibrosis) is inversely related to cardiac output and end-systolic volume exercise reserve; (2) greater thigh muscle fatty infiltration is inversely related to arteriovenous oxygen difference; both of which negatively influence VO 2 peak. Peak SV (R 2  = 65%) and thigh muscle fat fraction (R 2  = 68%) were similarly strong independent predictors of VO 2 peak in BCS and matched-CON combined. Post-anthracyclines, myocardial fibrosis is associated with impaired cardiac reserve, and thigh muscle fatty infiltration is associated with impaired oxygen extraction, which both contribute to VO 2 peak.

The conventional approach to cardiac magnetic resonance (CMR) involving breath holds, electrocardiography-gating, and acquisition of a short-axis (SAX) image stack, introduces technical and logistical challenges for assessing exercise left ventricular (LV) function. Real-time, free-breathing CMR acquisition of long-axis (LAX) images overcomes these issues and also enables assessment of global longitudinal strain (GLS). We evaluated the reliability of a free-breathing LAX approach compared to the standard SAX approach and the reproducibility of free-breathing LAX. LV SAX (contiguous stack) and LAX (two-chamber and four-chamber) 3T CMR cine images were acquired four times within one scan in 32 women with cardiovascular risk factors (56±10 years, 28±4 kg/m 2 ) as follows: 1) resting, gated-segmented, end-expiration breath-hold; 2) resting, real-time, free-breathing; 3) test-retest set of resting, real-time, free-breathing; 4) peak exercise (incremental-to-maximum, in-magnet, stepper test), real-time, free-breathing. A second scan was performed within one week in a subset (n = 5) to determine reproducibility of peak exercise measures. Reliability and agreement of the free-breathing LAX approach with the conventional SAX approach were assessed by intraclass correlation coefficient (ICC) and Bland-Altman plots, respectively. Normal control GLS reserve was also acquired in a separate set of 12 young, healthy control women (25±4 years, 22±2 kg/m 2 ) for comparison. Comparisons of LV volumes and function among all techniques at rest had good-to-excellent reliability (ICC = 0.80–0.96), and excellent reliability between peak exercise free-breathing LAX and SAX evaluations (ICC = 0.92–0.96). Higher resting heart rates with free-breathing acquisitions compared to breath-hold (mean difference, limits of agreement: 5, 1–12 beats per minute) reduced reliability for cardiac output (ICC = 0.67–0.79). Reproducibility of the free-breathing LAX approach was good-to-excellent at rest and peak exercise (ICC = 0.74–0.99). GLS exercise reserve was impaired in older women at cardiovascular risk compared to young healthy women (-4.7±2.3% vs -7.4±2.1%, p = 0.001). Real-time, free-breathing CMR with LAX evaluation provides a reliable and reproducible method to assess rest and peak exercise cardiac function, including GLS.

IntroductionInhibition capabilities have been shown to be a strong predictor of social and educational life outcomes (Mischel & Ebbesen, 1970; Shoda et al., 1990). Inhibition capabilities have an enormous impact on attention and impulsivity (Bari & Robbins, 2013). These two executive functions are associated with numerous psychiatric disorders but are not well understood in terms of white matter (WM) connectivity (Puiu et al., 2018). Novel techniques and statistical approaches in neuroimaging bring us closer to a biologically sustained model.ObjectivesThis research aims to: 1) identify WM connections associated with attention/impulsivity performance and 2) characterize the differences in WM microstructure associated with the variation of the performance.Methods157 children (GESTE cohort, 8-12 years, 27 Dx ADHD, 2 Dx ASD) with b=1500mm2/s, 2mm isotropic dMRI acquisitions were included. Tractography was performed with TractoFlow pipeline (Theaud et al., 2020). Dimensionality reduction of diffusion metrics yielded two components : microstructural complexity (DTI Metrics, AFD & NuFo) and axonal density (AFD_fixel) (Chamberland et al., 2019). Attention/impulsivity were evaluated with the CPT3. Multivariate linear regression was performed in python.ResultsLower microstructural complexity was associated with poorer attentional performance on regions of the parietal lobe to the occipital gyrus (P-O, p=0.044, R2=0.14, Figure 1.) and the Broadman’s area 8 to area 6 (SF8-SF6, p=0.002, R2=0.12, Figure 1.). Lower axonal density was associated with a less impulsive pattern on SF8-SF6 (p=0.001, R2=0.13, Figure 1.). Results remained significant when removing children with an ADHD or ASD diagnosis.ConclusionsWe identified underlying difference in WM microstructure that may be associated with the variation in attention/impulsivity performance in school-aged children.DisclosureNo significant relationships.

Trekking and military missions generally consist of carrying heavy loads for extreme durations. These factors have been separately shown to be sources of neuromuscular (NM) fatigue and locomotor alterations. However, the question of their combined effects remains unresolved, and addressing this issue required a representative context. The aim was to investigate the effects of extreme-duration heavy load carriage on NM function and walking characteristics. Ten experienced infantrymen performed a 21-h simulated military mission (SMM) in a middle-mountain environment with equipment weighing ∼27 kg during battles and ∼43 kg during marches. NM function was evaluated for knee extensors (KE) and plantar flexors (PF) pre- and immediately post-SMM using isometric maximal voluntary contraction (MVC) measurement, neural electrical stimulation and surface EMG. The twitch-interpolation method was used to assess central fatigue. Peripheral changes were examined by stimulating the muscle in the relaxed state. The energy cost, mechanical work and spatio-temporal pattern of walking were also evaluated pre-/post-SMM on an instrumented treadmill in three equipment conditions: Sportswear, Battle and March. After the SMM, MVC declined by -10.2±3.6% for KE (P<0.01) and -10.7±16.1% for PF (P = 0.06). The origin of fatigue was essentially peripheral for both muscle groups. A trend toward low-frequency fatigue was detected for KE (5.5%, P = 0.08). These moderate NM alterations were concomitant with a large increase in perceived fatigue from pre- (rating of 8.3±2.2) to post-SMM (15.9±2.1, P<0.01). The SMM-related fatigue did not alter walking energetics or mechanics, and the different equipment carried on the treadmill did not interact with this fatigue either. this study reports the first data on physiological and biomechanical consequences of extreme-duration heavy load carriage. Unexpectedly, NM function alterations due to the 21-h SMM were moderate and did not alter walking characteristics. Name: Effect of prolonged military exercises with high load carriage on neuromuscular fatigue and physiological/biomechanical responses. Number: NCT01127191.

Background and Purpose. With the current interest in stability training for the injured low back, the use of labile (movable) surfaces, underneath the subject, to challenge the motor control system is becoming more popular. Little is known about the modulating effects of these surfaces on muscle activity. The purpose of this study was to establish the degree of modulating influence of the type of surface (whether stable or labile) on the mechanics of the abdominal wall. In this study, the amplitude of muscle activity together with the way that the muscles coactivated due to the type of surface under the subject were of interest. Subjects. Eight men (mean age=23.3 years [SD=4.3], mean height=177.6 cm [SD=3.4], mean weight=72.6 kg [SD=8.7]) volunteered to participate in the study. All subjects were in good health and reported no incidence of acute or chronic low back injury or prolonged back pain prior to this experiment. Methods. All subjects were requested to perform 4 different curl-up exercises—1 on a stable surface and the other 3 on varying labile surfaces. Electromyographic signals were recorded from 4 different abdominal sites on the right and left sides of the body and normalized to maximal voluntary contraction (MVC) amplitudes. Results. Performing curl-up exercises on labile surfaces increased abdominal muscle activity (eg, for curl-up on a stable surface, rectus abdominis muscle activity was 21% of MVC and external oblique muscle activity was 5% of MVC; for curl-up with the upper torso on a labile ball, rectus abdominis muscle activity was 35% of MVC and external oblique muscle activity was 10% of MVC). Furthermore, it appears that increases in external oblique muscle activity were larger than those of other abdominal muscles. Conclusion and Discussion. Performing curl-ups on labile surfaces changes both the level of muscle activity and the way that the muscles coactivate to stabilize the spine and the whole body. This finding suggests a much higher demand on the motor control system, which may be desirable for specific stages in a rehabilitation program.

Abstract Background While cardiotoxic chemotherapy is known to negatively impact cardiac function and hemoglobin levels, the impact on skeletal muscle has been understudied among patients. The purpose was to longitudinally characterize myosteatosis (muscle fat), skeletal muscle metabolism, and oxygen (O2) consumption during cardiotoxic chemotherapy for breast cancer. Patients and Methods Thirty-four patients with stage I-III breast cancer were enrolled before trastuzumab-containing and/or anthracycline-containing chemotherapy. We used magnetic resonance imaging to non-invasively quantify thigh myosteatosis (fat-water imaging), and lower leg metabolism (31P spectroscopy), O2 consumption (custom techniques), and peak power output during single-leg plantarflexion exercise at pre-, mid-, end-chemotherapy, and 1-year. We also measured pulmonary VO2peak and maximal leg press strength. Results During chemotherapy, VO2peak and leg press strength decreased while peak plantarflexion power output was maintained. At mid-chemotherapy, hemoglobin decreased (16%) and lower leg blood flow increased (37%) to maintain lower leg O2 delivery; exercise Pi:PCr and myosteatosis increased. Between mid- and end-chemotherapy, lower leg O2 extraction (28%) and O2 consumption (21%) increased, while plantarflexion exercise efficiency (watts/O2 consumed) decreased. At one year, VO2peak and leg press strength returned to pre-chemotherapy levels, but lower leg exercise O2 extraction, consumption and Pi:PCr, and myosteatosis remained elevated. Conclusion Lower leg skeletal muscle blood flow and O2 extraction adapt to compensate for chemotherapy-related hemoglobin reduction for small muscle mass exercise but are insufficient to maintain large muscle mass exercise (pulmonary VO2peak, leg press strength). The excess O2 required to perform work, increased Pi:PCr ratio and myosteatosis together suggest suppressed fat oxidation during chemotherapy. Cardiotoxic chemotherapy is known to negatively affect cardiac function and hemoglobin levels, but its effect on skeletal muscle is less understood. This article examines the changes in skeletal muscle energy metabolism and oxygen consumption during cardiotoxic chemotherapy for early-stage breast cancer and evaluates chemotherapy-related changes in myosteatosis and related performance metrics.

Background Little information exists on the perceptions of psychiatrists regarding the implementation and various impacts of the consultation-liaison model. This model has been used in Quebec (Canada) through the function of specialist respondent-psychiatrists (SRP) since 2009. This study assessed the main activities, barriers or facilitators, and impact of SRP in adult and child-adolescent psychiatry on the capacity of service providers in primary care and youth centers to treat patients with mental health disorders (MHD). Methods Data included 126 self-administered questionnaires from SRP and semi-structured interviews from 48 SRP managers. Mixed methods were used, with qualitative findings from managers complementing the SRP survey. Comparative analyses of SRP responses in adult versus child-adolescent psychiatry were also conducted. Results Psychiatrists dedicated a median 24.12 h/month to the SRP function, mainly involving case discussions with primary care teams or youth centers. They were confident about the level of support they provided and satisfied with their influence in clinical decision-making, but less satisfied with the support provided by their organizations. SRP evaluated their impacts on clinical practice as moderate, particularly among general practitioners (GP). SRP working in child-adolescent psychiatry were more comfortable, motivated, and positive about their overall performance and impact than in adult psychiatry. Organizational barriers (e.g. team instability) were most prevalent, followed by system-level factors (e.g. network size and complexity, lack of resources, model inflexibility) and individual factors (e.g. GP reluctance to treat patients with MHD). Organizational facilitators included support from family medicine group directors, collaboration with university family medicine groups and coordination by liaison nurses; at the system level, pre-existing relationships and working in the same institution; while individual-level facilitators included SRP personality and strong organizational support. Conclusion Quebec SRP were implemented sparingly in family medicine groups and youth centers, while SRP viewed their overall impact as moderate. Results were more positive in child-adolescent psychiatry than in adult psychiatry. Increased support for the SRP function, adapting the model to GP in need of more direct support, and resolving key system issues may improve SRP effectiveness in terms of team stability, coordination among providers, access to MH services and readiness to implement innovations.

For those opposed to immigration, Miami is a nightmare. Miami is the de facto capital of Latin America; it is a city where immigrants dominate, Spanish is ubiquitous, and Denny's is an ethnic restaurant. Are Miami's immigrants representative of a trend that is undermining American culture and identity? Drawing from in-depth fieldwork in the city and looking closely at recent events such as the Elián González case, This Land Is Our Land examines interactions between immigrants and established Americans in Miami to address fundamental questions of American identity and multiculturalism. Rather than focusing on questions of assimilation, as many other studies have, this book concentrates on interethnic relations to provide an entirely new perspective on the changes wrought by immigration in the United States. A balanced analysis of Miami's evolution over the last forty years, This Land Is Our Land is also a powerful demonstration that immigration in America is not simply an \"us versus them\" phenomenon.

Quantifying the stability of the spinal column offers a perspective on the effectiveness of the motor control strategy to ensure a stable spine—and minimize the risk of injury from experiencing an unstable event. There are essentially three energy based methods of calculating a stability index for the lumbar spine. All three methods involve mathematical manipulation of an 18×18 Hessian matrix. The purpose of this paper was to consider the mathematical implications for the three methods of determining a single stability index, and examine the effects of biological factors such as muscle activation in each of these methods. The first approach computes the Hessian's determinant and is thought to represent a more global or “average” perspective on stability. A second approach computes the smallest eigenvalue of the Hessian matrix to determine the weakest link of the spine. The final method determines an average critical stiffness difference for the spine and is intended to effectively determines how far a human spine is from instability, and allows comparison between tasks. This study shows that the same interpretation of stability is achieved via all three computational approaches—they agree as to whether the spine is stable or not. However they appear to differ in their sensitivity to the effect of muscle activation patterns.

The CMS detector, including its muon system, has been operating at the CERN LHC in increasingly challenging conditions for about 15 years. The muon detector was designed to provide excellent triggering and track reconstruction for muons produced in proton–proton collisons at an instantaneous luminosity ( L ) of 1 × 10 34  cm - 2 s - 1 . During the Run 2 data-taking period (2015–2018), the LHC achieved an instantaneous luminosity of twice its design value, resulting in larger background rates and making the efficient detection of muons more difficult. While some backgrounds result from natural radioactivity, cosmic rays, and interactions of the circulating protons with residual gas in the beam pipe, the dominant source of background hits in the muon system arises from proton–proton interactions themselves. Charged hadrons leaving the calorimeters produce energy deposits in the muon chambers. In addition, high-energy particles interacting in the hadron calorimeter and forward shielding elements generate thermal neutrons, which leak out of the calorimeter and shielding structures, filling the CMS cavern. We describe the method used to measure the background rates in the various muon subsystems. These rates, in conjunction with simulations, can be used to estimate the expected backgrounds in the High-Luminosity LHC. This machine will run for at least 10 years starting in 2029 reaching an instantaneous luminosity of L = 5 × 10 34 cm -2 s -1 and increasing ultimately to L = 7.5 × 10 34 cm -2 s -1 . These background estimates have been a key ingredient for the planning and design of the muon detector upgrade.