Bibliographies thématiques / Prolonged muscle unloading (bed-rest)

Littérature scientifique sur le sujet « Prolonged muscle unloading (bed-rest) »

Auteur : Grafiati
Publié le 11 mars 2023

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Articles de revues sur le sujet "Prolonged muscle unloading (bed-rest)"

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Arbogast, Sandrine, Jacqueline Smith, Yves Matuszczak, Brian J. Hardin, Jennifer S. Moylan, Jeffrey D. Smith, Jeffrey Ware, Ann R. Kennedy et Michael B. Reid. « Bowman-Birk inhibitor concentrate prevents atrophy, weakness, and oxidative stress in soleus muscle of hindlimb-unloaded mice ». Journal of Applied Physiology 102, no 3 (mars 2007) : 956–64. http://dx.doi.org/10.1152/japplphysiol.00538.2006.

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Antigravity muscles atrophy and weaken during prolonged mechanical unloading caused by bed rest or spaceflight. Unloading also induces oxidative stress in muscle, a putative cause of weakness. We tested the hypothesis that dietary supplementation with Bowman-Birk inhibitor concentrate (BBIC), a soy protein extract, would oppose these changes. Adult mice were fed a diet supplemented with 1% BBIC during hindlimb unloading for up to 12 days. Soleus muscles of mice fed the BBIC-supplemented diet weighed less, developed less force per cross-sectional area, and developed less total force after unloading than controls. BBIC supplementation was protective, blunting decrements in soleus muscle weight and force. Cytosolic oxidant activity was assessed using 2′,7′-dichlorofluorescin diacetate. Oxidant activity increased in unloaded muscle, peaking at 3 days and remaining elevated through 12 days of unloading. Increases in oxidant activity correlated directly with loss of muscle mass and were abolished by BBIC supplementation. In vitro assays established that BBIC directly buffers reactive oxygen species and also inhibits serine protease activity. We conclude that dietary supplementation with BBIC protects skeletal muscle during prolonged unloading, promoting redox homeostasis in muscle fibers and blunting atrophy-induced weakness.
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Marusic, Uros, Marco Narici, Bostjan Simunic, Rado Pisot et Ramona Ritzmann. « Nonuniform loss of muscle strength and atrophy during bed rest : a systematic review ». Journal of Applied Physiology 131, no 1 (1 juillet 2021) : 194–206. http://dx.doi.org/10.1152/japplphysiol.00363.2020.

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Our study contributes to the characterization of muscle loss and weakness processes reflected by a logarithmic decline in muscle strength induced by chronic bed rest. Acute short-term hospitalization (≤5 days) associated with periods of disuse/immobilization/prolonged time in the supine position in the hospital bed is sufficient to significantly decrease muscle mass and size and induce functional changes related to weakness in maximal muscle strength. By bringing together integrated evaluation of muscle structure and function, this work identifies that 79% of the loss in muscle strength can be explained by muscle atrophy, leaving 21% of the functional loss unexplained. The outcomes of this study should be considered in the development of daily countermeasures for preserving neuromuscular integrity as well as preconditioning interventions to be implemented before clinical bed rest or chronic gravitational unloading (e.g., spaceflights).
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Lovejoy, Jennifer C., Steven R. Smith, Jeffrey J. Zachwieja, George A. Bray, Marlene M. Windhauser, Peter J. Wickersham, Johannes D. Veldhuis, Richard Tulley et Jacques A. de la Bretonne. « Low-dose T3 improves the bed rest model of simulated weightlessness in men and women ». American Journal of Physiology-Endocrinology and Metabolism 277, no 2 (1 août 1999) : E370—E379. http://dx.doi.org/10.1152/ajpendo.1999.277.2.e370.

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This study tested the hypothesis that low-dose 3,5,3′-triiodothyronine (T3) administration during prolonged bed rest improves the ground-based model of spaceflight. Nine men (36.4 ± 1.3 yr) and five women (34.2 ± 2.1 yr) were studied. After a 5-day inpatient baseline period, subjects were placed at total bed rest with 6° head-down tilt for 28 days followed by 5-day recovery. Fifty micrograms per day of T3( n = 8) or placebo ( n = 6) were given during bed rest. Serum T3 concentrations increased twofold, whereas thyroid-stimulating hormone was suppressed in treated subjects. T3-treated subjects showed significantly greater negative nitrogen balance and lost more weight ( P = 0.02) and lean mass ( P < 0.0001) than placebo subjects. Protein breakdown (whole body [13C]leucine kinetics) increased 31% in the T3 group but only 8% in the placebo group. T3-treated women experienced greater changes in leucine turnover than men, despite equivalent weight loss. Insulin sensitivity fell by 50% during bed rest in all subjects ( P = 0.005), but growth hormone release and insulin release were largely unaffected. In conclusion, addition of low-dose T3 to the bed rest model of muscle unloading improves the ground-based simulation of spaceflight and unmasks several important gender differences.
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Westby, Christian M., David S. Martin, Stuart M. C. Lee, Michael B. Stenger et Steven H. Platts. « Left ventricular remodeling during and after 60 days of sedentary head-down bed rest ». Journal of Applied Physiology 120, no 8 (15 avril 2016) : 956–64. http://dx.doi.org/10.1152/japplphysiol.00676.2015.

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Short periods of weightlessness are associated with reduced stroke volume and left ventricular (LV) mass that appear rapidly and are thought to be largely dependent on plasma volume. The magnitude of these cardiac adaptations are even greater after prolonged periods of simulated weightlessness, but the time course during and the recovery from bed rest has not been previously described. We collected serial measures of plasma volume (PV, carbon monoxide rebreathing) and LV structure and function [tissue Doppler imaging, three-dimensional (3-D) and 2-D echocardiography] before, during, and up to 2 wk after 60 days of 6° head down tilt bed rest (HDTBR) in seven healthy subjects (four men, three women). By 60 days of HDTBR, PV was markedly reduced (2.7 ± 0.3 vs. 2.3 ± 0.3 liters, P < 0.001). Resting measures of LV volume and mass were ∼15% ( P < 0.001) and ∼14% lower ( P < 0.001), respectively, compared with pre-HDTBR values. After 3 days of reambulation, both PV and LV volumes were not different than pre-HDTBR values. However, LV mass did not recover with normalization of PV and remained 12 ± 4% lower than pre-bed rest values ( P < 0.001). As previously reported, decreased PV and LV volume precede and likely contribute to cardiac atrophy during prolonged LV unloading. Although PV and LV volume recover rapidly after HDTBR, there is no concomitant normalization of LV mass. These results demonstrate that reduced LV mass in response to prolonged simulated weightlessness is not a simple effect of tissue dehydration, but rather true LV muscle atrophy that persists well into recovery.
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Mazzatti, Dawn J., Melissa A. Smith, Radu C. Oita, Fei-Ling Lim, Andrew J. White et Michael B. Reid. « Muscle unloading-induced metabolic remodeling is associated with acute alterations in PPARδ and UCP-3 expression ». Physiological Genomics 34, no 2 (juillet 2008) : 149–61. http://dx.doi.org/10.1152/physiolgenomics.00281.2007.

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A number of physiological changes follow prolonged skeletal muscle unloading as occurs in spaceflight, bed rest, and hindlimb suspension (HLS) and also in aging. These include muscle atrophy, fiber type switching, and loss of the ability to switch between lipid and glucose usage, or metabolic inflexibility. The signaling and genomic events that precede these physiological manifestations have not been investigated in detail, particularly in regard to loss of metabolic flexibility. Here we used gene arrays to determine the effects of 24-h HLS on metabolic remodeling in mouse muscle. Acute unloading resulted in differential expression of a number of transcripts in soleus and gastrocnemius muscle, including many involved in lipid and glucose metabolism. These include the peroxisome proliferator-activated receptors (PPARs). In contrast to Ppar-α and Ppar-γ, which were downregulated by acute HLS, Ppar-δ was upregulated concomitant with increased expression of its downstream target, uncoupling protein-3 ( Ucp-3). However, differential expression of Ppar-δ was both acute and transient in nature, suggesting that regulation of PPARδ may represent an adaptive, compensatory response aimed at regulating fuel utilization and maintaining metabolic flexibility.
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Radek, Katherine A., Lisa A. Baer, Jennifer Eckhardt, Luisa A. DiPietro et Charles E. Wade. « Mechanical unloading impairs keratinocyte migration and angiogenesis during cutaneous wound healing ». Journal of Applied Physiology 104, no 5 (mai 2008) : 1295–303. http://dx.doi.org/10.1152/japplphysiol.00977.2007.

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Although initially thought to improve an individual's ability to heal, mechanical unloading promoted by extended periods of bed rest has emerged as a contributing factor to delayed or aberrant tissue repair. Using a rat hindlimb unloading (HLU) model of hypogravity, we mimicked some aspects of physical inactivity by removing weight-bearing loads from the hindlimbs and producing a systemic cephalic fluid shift. This model simulates bed rest in that the animal undergoes physiological adaptations, resulting in a reduction in exercise capability, increased frequency of orthostatic intolerance, and a reduction in plasma volume. To investigate whether changes associated with prior prolonged bed rest correlate with impaired cutaneous wound healing, we examined wound closure, angiogenesis, and collagen content in day 2 to day 21 wounds from rats exposed to HLU 2 wk before excisional wounding. Wound closure was delayed in day 2 wounds from HLU rats compared with ambulatory controls. Although the levels of proangiogenic growth factors, fibroblast growth factor-2 (FGF-2), and vascular endothelial growth factor (VEGF) were similar between the two groups, wound vascularity was significantly reduced in day 7 wounds from HLU animals. To further examine this disparity, total collagen content was assessed but found to be similar between the two groups. Taken together, these results suggest that keratinocyte and endothelial cell function may be impaired during the wound healing process under periods of prolonged inactivity or bed rest.
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Yamashita-Goto, Katsumasa, Ryoko Okuyama, Masanori Honda, Kensuke Kawasaki, Kazuhiko Fujita, Takahiro Yamada, Ikuya Nonaka, Yoshinobu Ohira et Toshitada Yoshioka. « Maximal and submaximal forces of slow fibers in human soleus after bed rest ». Journal of Applied Physiology 91, no 1 (1 juillet 2001) : 417–24. http://dx.doi.org/10.1152/jappl.2001.91.1.417.

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The effects of 2 and 4 mo of bed rest, with or without exercise countermeasures, on the contractile properties of slow fibers in the human soleus muscle were examined. Mean fiber diameters were 8 and 36% smaller after 2 and 4 mo of bed rest, respectively, than the pre-bed rest level. Maximum tetanic force (Po), maximum activated force (Fmax) per cross-sectional area (CSA), and the common-logarithm value of free Ca2+concentration required for half-maximal activation (pCa50) also decreased after 2 and 4 mo of bed rest. In contrast, maximum unloaded shortening velocity ( V o) was increased after 2 and 4 mo of bed rest. After 1 mo of recovery, fiber diameters, Po, Fmax per CSA ( P > 0.05), and pCa50 were increased and V odecreased toward pre-bed rest levels. Effects of knee extension/flexion exercise by wearing an anti-G Penguin suit for 10 h daily, and the effects of loading or unloading of the plantar flexors with (Penguin-1) or without (Penguin-2) placing the elastic loading elements of the suit, respectively, were investigated during ∼2 mo of bed rest. In the Penguin-1 group, mean fiber diameter, Po, Fmax per CSA, V o, and pCa50 were similar before and after bed rest. However, the responses of fiber size and contractile properties to bed rest were not prevented in the Penguin-2 group, although the degree of the changes was less than those induced by bed rest without any countermeasure. These results indicate that long-term bed rest results in reductions of fiber size, force-generation capacity, and Ca2+sensitivity, and enhancement of shortening velocity in slow fibers of the soleus. The data indicate that continuous mechanical loading on muscle, such as stretching of muscle, is an effective countermeasure for the prevention of muscular adaptations to gravitational unloading.
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Clarke, Mark S. F., Marcas M. Bamman et Daniel L. Feeback. « Bed rest decreases mechanically induced myofiber wounding and consequent wound-mediated FGF release ». Journal of Applied Physiology 85, no 2 (1 août 1998) : 593–600. http://dx.doi.org/10.1152/jappl.1998.85.2.593.

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Using a terrestrial model of spaceflight (i.e., bed rest), we investigated the amount of myofiber wounding and fibroblast growth factor (FGF) release that occurs during unloading. Myofiber wounding was determined by serum levels of the creatine kinase MM (CKMM) isoform before and after bed rest. Serum levels of both acidic FGF (aFGF) and basic FGF were also determined. A second group of subjects was treated in an identical fashion except that they underwent a resistive exercise program during bed rest. Bed rest alone caused significant ( P < 0.05; n = 7) reductions in post-bed-rest serum levels of both CKMM and aFGF, which were paralleled by a significant ( P < 0.05; n = 7) decrease in myofiber size. In contrast, bed rest plus resistive exercise resulted in significant ( P < 0.05; n = 7) increases in post-bed-rest serum levels of both CKMM and aFGF, which were paralleled by inhibition of the atrophic response. These results suggest that mechanically induced, myofiber wound-mediated FGF release may play an important role in the etiology of unloading-induced skeletal muscle atrophy.
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Rullman, Eric, Rodrigo Fernandez-Gonzalo, Igor B. Mekjavić, Thomas Gustafsson et Ola Eiken. « MEF2 as upstream regulator of the transcriptome signature in human skeletal muscle during unloading ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 315, no 4 (1 octobre 2018) : R799—R809. http://dx.doi.org/10.1152/ajpregu.00452.2017.

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Our understanding of skeletal muscle structural and functional alterations during unloading has increased in recent decades, yet the molecular mechanisms underpinning these changes have only started to be unraveled. The purpose of the current investigation was to assess changes in skeletal muscle gene expression after 21 days of bed rest, with a particular focus on predicting upstream regulators of muscle disuse. Additionally, the association between differential microRNA expression and the transcriptome signature of bed rest were investigated. mRNAs from musculus vastus lateralis biopsies obtained from 12 men before and after the bed rest were analyzed using a microarray. There were 54 significantly upregulated probesets after bed rest, whereas 103 probesets were downregulated (false discovery rate 10%; fold-change cutoff ≥1.5). Among the upregulated genes, transcripts related to denervation-induced alterations in skeletal muscle were identified, e.g., acetylcholine receptor subunit delta and perinatal myosin. The most downregulated transcripts were functionally enriched for mitochondrial genes and genes involved in mitochondrial biogenesis, followed by a large number of contractile fiber components. Upstream regulator analysis identified a robust inhibition of the myocyte enhancer factor-2 (MEF2) family, in particular MEF2C, which was suggested to act upstream of several key downregulated genes, most notably peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α)/peroxisome proliferator-activated receptors (PPARs) and CRSP3. Only a few microRNAs were identified as playing a role in the overall transcriptome picture induced by sustained bed rest. Our results suggest that the MEF2 family is a key regulator underlying the transcriptional signature of bed rest and, hence, ultimately also skeletal muscle alterations induced by systemic unloading in humans.
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Belavý, Daniel L., Carolyn A. Richardson, Stephen J. Wilson, Dieter Felsenberg et Jörn Rittweger. « Tonic-to-phasic shift of lumbo-pelvic muscle activity during 8 weeks of bed rest and 6-months follow up ». Journal of Applied Physiology 103, no 1 (juillet 2007) : 48–54. http://dx.doi.org/10.1152/japplphysiol.00850.2006.

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Prior motor control studies in unloading have shown a tonic-to-phasic shift in muscle activation, particularly in the short extensors. Tonic muscle activity is considered critical for normal musculoskeletal function. The shift from tonic-to-phasic muscle activity has not been systematically studied in humans in unloading nor at the lumbo-pelvic (LP) region. Ten healthy young male subjects underwent 8 wk of bed rest with 6-mo follow up as part of the “Berlin Bed-Rest Study.” A repetitive knee movement model performed in the prone position is used to stimulate tonic holding LP muscle activity, as measured by superficial EMG. Tonic and phasic activation patterns were quantified by relative height of burst vs. baseline electromyographic linear-envelope signal components. Statistical analysis shows a shift toward greater phasic activity during bed rest and follow up ( P < 0.001) with a significant interaction across muscles ( P < 0.001) specifically affecting the short lumbar extensors. These changes appear unrelated to skill acquisition over time ( P all ≥0.196). This change of a shift from tonic LP muscle activation to phasic is in line with prior research on the effects of reduced weight bearing on motor control.
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Thèses sur le sujet "Prolonged muscle unloading (bed-rest)"

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Alkner, Björn. « Effects of unloading and resistance exercise on skeletal muscle function, size and composition in man / ». Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-482-1/.

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Chapitres de livres sur le sujet "Prolonged muscle unloading (bed-rest)"

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Hudson, Donald, et Sean Moodley. « Pressure ulcers ». Dans Oxford Textbook of Plastic and Reconstructive Surgery, sous la direction de Andrew Fleming, 1223–46. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780199682874.003.0108.

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Pressure ulcers are a problem worldwide with social and cost implications. Patients at special risk are paraplegics, those in intensive care units who are critically sick, and older patients having prolonged bed rest for whatever reason. The important extrinsic factors are pressure, shear, and friction. There are a number of charts, which endeavour to identify patients at risk, and institute appropriate preventative measures thereby avoiding the long-term sequelae and burden of pressure ulcers. In patients with established pressure ulcers, an accurate patient and wound evaluation is vitally important. The long-term success of management of these ulcers is dependent on good patient rehabilitation and optimization of the wound. Reconstructive success is improved by following surgical guidelines. Use of fasciocutaneous flaps, designed in a V–Y configuration, is the preferred method of reconstruction with muscle flaps reserved as a back-up option. Conscientious postoperative care is equally important at ensuring a successful surgical outcome and minimizing complications
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