Analysis of the rate of force development reveals high neuromuscular fatigability in elderly patients with chronic kidney disease

Background Chronic kidney disease (CKD) induces muscle wasting and a reduction in the maximum voluntary force (MVF). Little is known about the neuromuscular fatigability in CKD patients, defined as the reduction of muscle force capacities during exercise. Neuromuscular fatigability is a crucial physical parameter of the daily living. The quantification of explosive force has been shown to be a sensitive means to assess neuromuscular fatigability. Thus, our study used explosive force estimates to assess neuromuscular fatigability in elderly CKD patients. Methods Inclusion criteria for CKD patients were age $\ge$ 60 years old and glomerular filtration rate (GFR) < 45 mL/ min/1.73 m 2 not on dialysis, and those for controls were GFR > 60 mL/min/1.73 m 2 , age and diabetes matched. The fatigability protocol focused on a handgrip task coupled with surface electromyography (sEMG). Scalars were extracted from the rate of force development (RFD): absolute and normalized time periods (50, 75, 100, 150 and 200 ms, RFD 50 , RFD 75 , RFD 100 , RFD 150 and RFD 200 , respectively), peak RFD (RFD peak in absolute; NRFD peak normalized), timeto-peak RFD (t-RFD peak) and the relative force at RFD peak (MVF-RFD peak). A statistical parametric mapping approach was performed on the force, impulse and RFD-time curves. The integrated sEMG with time at 0-30, 0-50, 0-100 and 0-200 ms time intervals relative to onset of sEMG activity was extracted and groups were compared separately for each sex. Results The cohort of 159 individuals had a median age of 69 (9 IQR) years and body mass index was 27.6 (6.2 IQR) kg/ m 2. Propensity-score-matched groups balanced CKD patients and controls by gender with 66 males and 34 females. In scalar analysis, CKD patients manifested a higher decrement than controls in the early phase of contraction, regarding the NRFD peak (P = 0.009; $\eta$ 2 p = 0.034) and RFD 75 and RFD 100 (for both P < 0.001; $\eta$ 2 p = 0.068 and 0.064). The onedimensional analysis confirmed that CKD males manifest higher and delayed neuromuscular fatigability, especially before 100 ms from onset of contraction. sEMG was lower in CKD patients than controls in the 0-100 ms (at rest: P = 0.049, Cohen's d = 0.458) and 0-200 ms (at rest: P = 0.016, Cohen's d = 0.496; during exercise: P = 0.006, Cohen's d = 0.421) time windows. Controls showed greater decrease of sEMG than CKD patients in the 0-30 ms (P = 0.020, Cohen's d = 0.533) and 0-50 ms (P = 0.010, Cohen's d = 0.640) time windows. As opposite to females, males showed almost the same differences between groups. Conclusions Our study is the first to show that CKD patients have higher fatigability than controls, which may be associated with an impaired motor-unit recruitment, highlighting a neural drive disturbance with CKD. Further studies are needed to confirm these findings.Comment: Journal of Cachexia, Sarcopenia and Muscle, In pres

Investigation of gelation phenomena of some polysaccharides by ultrasonic spectroscopy

International audienceThe gelation process of two polysaccharides, amy lose and alginate, has been investigated by means of ultrasonic spectroscopy. This method allows an immediate analysis of the acoustic wave propagating through the medium by means of Fast Fourier Transform of the signals. Measurements were performed within the frequency range 15–100 MHz. The absorption and the velocity of the ultrasonic wave can therefore be obtained as a function of time over a given frequency range. The results were compared to classical rheological measurements in oscillatory shear at a low strain amplitude and, in case of amylose, to turbidity variations. In the course of amy lose gelation, variations in the absorption of the ultrasonic signal paralleled those of turbidity in the medium and took place at a much earlier stage than the one at which the increase in G′ and G″ can be detected. In the case of alginate, absorption variations paralleled more closely those of the viscoelastic parameters G′ and G″. The differences can be interpreted in relation to the mechanisms of gelation. Amylose gelation takes place through a phase separation. Ultrasound appears extremely sensitive to such changes in the material. The method shows the first steps in the phase separation phenomenon. This suggests that variations in the ultrasonic absorption can be taken as a means to detect the earlier steps of the gelation process of starchy materials. Gelation of alginate is a calcium-mediated process, in which case, ultrasounds provide similar information as rheological measurements

Pedobarographic Statistical Parametric Mapping may identify specific plantar pressure patterns in patients with diabetes mellitus among different degrees of peripheral neuropathy: a pilot study

International audienc

Investigation of Acid Sites in a Zeotypic Giant Pores Chromium(III) Carboxylate

66 FIELD Section Title:Surface Chemistry and Colloids Laboratoire Catalyse et Spectrochimie, UMR 6506 CNRS,ENSICAEN and Universite de Caen,Caen,Fr. FIELD URL: written in English.A study of the zeotypic giant pores chromium(III) tricarboxylate CrIII3OFx(OH)1-x(H2O)2.{C6H3-(CO2)3}2.nH2O (MIL-100) has been performed. First, its thermal behavior, studied by X-ray thermodiffractometry and IR spectroscopy, indicates that the departure of water occurs without any pore contraction and no loss in crystallinity, which confirms the robustness of the framework. In a second step, IR spectroscopy has shown the presence of three distinct types of hydroxy groups depending on the outgassing conditions; first, at high temps. (573 K), only Cr-OH groups with a medium Bronsted acidity are present; at lower temps., two types of Cr-H2O terminal groups are obsd.; and at room temp., their relatively high Bronsted acidity allows them to combine with H-bonded water mols. Finally, a CO sorption study has revealed that at least three Lewis acid sites are present in MIL-100 and that fluorine atoms are located on a terminal position on the trimers of octahedra. A first result of grafting of methanol mols. acting as basic org. mols. on the chromium sites has also been shown, opening the way for a postsynthesis functionalization of MIL-100

Neural Drive Impairment in Chronic Kidney Disease Patients Is Associated with Neuromuscular Fatigability and Fatigue

International audienceIntroductionChronic kidney disease (CKD) patients have a high degree of fatigue relating to neuromuscular symptoms. There is a lack of evidence regarding the etiology of neuromuscular fatigability in elderly CKD patients.MethodsInclusion criteria are as follows: age ≥60 yr, glomerular filtration rate (GFR) 60 mL·min−1·1.73 m−2 in controls. The fatigability protocol consisted in a submaximal handgrip task at 40% peak force. Fatigue was assessed using the Multidimensional Fatigue Inventory–20 items (MFI-20) and the Functional Assessment of Chronic Illness Therapy–Fatigue questionnaires. Peak rate of force development (RFDpeak, normalized: NRFDpeak) and rate of EMG rise (RER) were measured during explosive contractions; peak force and mean surface EMG were measured during maximum voluntary contractions. Multilevel models tested neuromuscular parameters adjusted for clinical and Multidimensional Fatigue Inventory–20 items subscales. Neuromuscular fatigability contribution to fatigue description was tested using model comparison.ResultsThe study included 102 participants; 45 CKD patients and 57 controls. CKD mainly affected the mental and the reduced motivation subscales of fatigue. CKD was associated with greater neuromuscular fatigability assessed using NRFDpeak (group–time interaction, −16.7 % MVF·s−1, P = 0.024), which increased with fatigue severity (P = 0.018) and with a higher rate of decrement in RER compared with controls (RER at 50 ms: β = −121.2 μV·s−1, P = 0.016, and β = −48.5 μV·s−1, P = 0.196, respectively). Furthermore, these patients show an association between the reduced motivation subscale and the RER (e.g., 30 ms: β = −59.8% EMGpeak·s−1, P < 0.001). Only peak force fatigability contributed to fatigue variance, whereas RFDpeak did not.ConclusionsIn CKD patients, the neuromuscular fatigability assessed using RFDpeak is related to an impairment in motor-unit recruitment or discharge rates, whereas only peak force fatigability was related to fatigue. This suggests that targeting exercise interventions might lessen fatigue and improve quality of life in CKD patients

PhysIOpathology of NEuromuscular function rElated to fatigue in chronic Renal disease in the elderly (PIONEER): study protocol

International audienc