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Miyachi R, Morita Y, Yamazaki T. Division of loading time in reloading the disused atrophic soleus muscle induces proximal muscle injury. J Phys Ther Sci 2023; 35:193-198. [PMID: 36866019 PMCID: PMC9974327 DOI: 10.1589/jpts.35.193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/01/2022] [Indexed: 03/04/2023] Open
Abstract
[Purpose] This study aimed to compare the effects of loading time division in reloading atrophied muscles in different muscle long-axis regions. [Materials and Methods] We divided 8-week-old male Wistar rats into control (CON), 14-day hindlimb suspension (HS), 7-day hindlimb suspension followed by 60-min reloading for 7 consecutive days (WO), and 7-day hindlimb suspension followed by 60-min reloading on two separate occasions for 7 days (WT) groups. After the experimental period, muscle fibre cross-sectional area and necrotic fibre/central nuclei fibre ratio were measured in the soleus muscle's proximal, middle, and distal regions. [Results] The necrotic fibre/central nuclei fibre ratio was higher in the WT group than in the other groups in the proximal region. Proximal muscle fibre cross-sectional area was higher in the CON group than in the other groups. In the middle region, only HS group had muscle fibre cross-sectional area lower than the CON group. Similarly, muscle fibre cross-sectional area of the HS group was lower than the CON and WT groups in the distal region. [Conclusion] When reloading atrophied muscles, dividing the loading time can inhibit atrophy in the distal region but induce muscle injury in the proximal region.
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Affiliation(s)
- Ryo Miyachi
- Faculty of Health and Medical Sciences, Hokuriku
University: 1-1 Taiyogaoka, Kanazawa, Ishikawa 920-1180, Japan,Corresponding author. Ryo Miyachi (E-mail: )
| | - Yui Morita
- Department of Rehabilitation, Tokyo Medical and Dental
University Hospital, Japan
| | - Toshiaki Yamazaki
- Faculty of Health Sciences, Institute of Medical,
Pharmaceutical and Health Sciences, Kanazawa University, Japan
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Reidy PT, Edvalson LT, McKenzie AI, Petrocelli JJ, Mahmassani ZS, Drummond MJ. Neuromuscular electrical stimulation and protein during bed rest increases CD11b + skeletal muscle macrophages but does not correspond to muscle size or insulin sensitivity. Appl Physiol Nutr Metab 2020; 45:1261-1269. [PMID: 32470312 PMCID: PMC9236569 DOI: 10.1139/apnm-2020-0064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
With this cohort, we previously demonstrated preservation of thigh lean tissue with neuromuscular electrical stimulation combined with protein supplementation (NMES+PRO) treatment during bed rest in healthy older adults. Because macrophage polarization plays a significant role in the repair and maintenance of muscle size and insulin sensitivity, we hypothesized that muscle macrophages would be induced by NMES+PRO and would correspond to an increase in lean mass and an attenuated insulin resistance response altered by bed rest. Older adults (60-80 years old; body mass index < 30 kg/m2) underwent 5 days of bed rest and were randomized to either thrice daily treatment of NMES+PRO (n = 8) or CON (n = 8). Lean mass, insulin sensitivity, and markers of muscle macrophages, inflammation, and connective tissue were determined before and after bed rest. Glucose intolerance and insulin resistance occurred after bed rest but there was not a treatment effect (p > 0.10). Proinflammatory-like macrophages (CD11b+, CD206-) increased (p < 0.05) with NMES+PRO treatment and was different than CON. Minor changes in noncontractile tissue were observed. However, changes in muscle macrophages or extracellular matrix were not related to the preservation of thigh lean mass or insulin resistance. Daily NMES+PRO treatment during bed rest induced a muscle proinflammatory-like macrophage response and was unrelated to muscle size or metabolic function. This study is listed as clinical trial NCT02566590. Novelty Neuromuscular electrical stimulation combined with protein supplementation (NMES+PRO) increased proinflammatory-like macrophages and extracellular matrix content in older adults after bed rest. NMES+PRO changes in macrophages and noncontractile tissue macrophages were not related to muscle size preservation or insulin sensitivity.
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Affiliation(s)
- Paul T Reidy
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA
| | - Logan T Edvalson
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA
| | - Alec I McKenzie
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA
| | - Jonathan J Petrocelli
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA
| | - Ziad S Mahmassani
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA
| | - Micah J Drummond
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA
- Department of Nutrition and Integrative Physiology, University of Utah, 250 S. 1850 E, Room 214, Salt Lake City, UT 84112, USA
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The D2.mdx mouse as a preclinical model of the skeletal muscle pathology associated with Duchenne muscular dystrophy. Sci Rep 2020; 10:14070. [PMID: 32826942 PMCID: PMC7442653 DOI: 10.1038/s41598-020-70987-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/23/2020] [Indexed: 01/08/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked, lethal muscle degenerative disease caused by loss of dystrophin protein. DMD has no cure and few treatment options. Preclinical efforts to identify potential DMD therapeutics have been hampered by lack of a small animal model that recapitulates key features of the human disease. While the dystrophin-deficient mdx mouse on the C57BL/10 genetic background (B10.mdx) is mildly affected, a more severe muscle disease is observed when the mdx mutation is crossed onto the DBA/2J genetic background (D2.mdx). In this study, the functional and histological progression of the D2.mdx skeletal muscle pathology was evaluated to determine the distinguishing features of disease. Data herein details the muscular weakness and wasting exhibited by D2.mdx skeletal muscle, as well as severe histopathological features, which include the rapid progression of fibrosis and calcifications in the diaphragm and progressive fibrosis accumulation in limb muscles. Furthermore, a timeline of D2.mdx progression is provided that details distinct stages of disease progression. These data support the D2.mdx as a superior small animal model for DMD, as compared to the B10.mdx model. The insights provided in this report should facilitate the design of preclinical evaluations for potential DMD therapeutics.
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Reidy PT, Yonemura NM, Madsen JH, McKenzie AI, Mahmassani ZS, Rondina MT, Lin YK, Kaput K, Drummond MJ. An accumulation of muscle macrophages is accompanied by altered insulin sensitivity after reduced activity and recovery. Acta Physiol (Oxf) 2019; 226:e13251. [PMID: 30632274 DOI: 10.1111/apha.13251] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/05/2019] [Accepted: 01/07/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Mechanisms underlying physical inactivity-induced insulin resistance are not well understood. In addition to a role in muscle repair, immune cell populations such as macrophages may regulate insulin sensitivity. AIM The aim of this study was to examine if the dynamic changes in insulin sensitivity during and after recovery from reduced physical activity corresponded to changes in skeletal muscle macrophages. METHODS In this prospective clinical study, we collected muscle biopsies from healthy older adults (70 ± 2 years, n = 12) before and during a hyperinsulinaemic-euglycaemic clamp and this occurred before (PRE) and after 2-week reduced physical activity (RA), and following 2-week of recovery (REC). Insulin sensitivity (hyperinsulinaemic-euglycaemic clamp), skeletal muscle mRNA expression of inflammatory markers, and immunofluorescent quantification of skeletal muscle macrophages, myofibre-specific satellite cell and capillary content were assessed. RESULTS Insulin sensitivity was decreased following reduced activity and rebounded following recovery above PRE levels. We observed an increase (P < 0.01) in muscle macrophages (CD68+ CD206+ : 190 [55, 324]; CD11b+ CD206+ : 117 [28, 205]% change from PRE) and CD68 (2.4 [1.4, 3.4]-fold) and CCL2 (1.9 [1.3, 2.5]-fold) mRNA following RA concurrent with increased (P < 0.03) satellite cells (55 [6, 104]%) in slow-twitch myofibres. Moreover, the distance of satellite cells to the nearest capillary was increased 7.7 (1.7, 13.7) µm in fast-twitch myofibres at RA (P = 0.007). Changes in macrophages were positively associated with increased insulin sensitivity following RA (R > 0.57, P < 0.05). CONCLUSION These findings suggested that a dynamic response of skeletal muscle macrophages following acute changes in physical activity in healthy older adults is related to insulin sensitivity.
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Affiliation(s)
- Paul T. Reidy
- Departments of Physical Therapy and Athletic Training University of Utah Salt Lake City Utah
| | - Nikol M. Yonemura
- Departments of Physical Therapy and Athletic Training University of Utah Salt Lake City Utah
| | | | - Alec I. McKenzie
- Departments of Physical Therapy and Athletic Training University of Utah Salt Lake City Utah
| | - Ziad S. Mahmassani
- Departments of Physical Therapy and Athletic Training University of Utah Salt Lake City Utah
| | - Matthew T. Rondina
- Department of Internal Medicine University of Utah School of Medicine Salt Lake City Utah
| | - Yu Kuei Lin
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine University of Utah School of Medicine Salt Lake City Utah
| | - Katie Kaput
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine University of Utah School of Medicine Salt Lake City Utah
| | - Micah J. Drummond
- Departments of Physical Therapy and Athletic Training University of Utah Salt Lake City Utah
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Nutritional strategies to counteract muscle atrophy caused by disuse and to improve recovery. Nutr Res Rev 2013; 26:149-65. [PMID: 23930668 DOI: 10.1017/s0954422413000115] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Periods of immobilisation are often associated with pathologies and/or ageing. These periods of muscle disuse induce muscle atrophy which could worsen the pathology or elderly frailty. If muscle mass loss has positive effects in the short term, a sustained/uncontrolled muscle mass loss is deleterious for health. Muscle mass recovery following immobilisation-induced atrophy could be critical, particularly when it is uncompleted as observed during ageing. Exercise, the best way to recover muscle mass, is not always applicable. So, other approaches such as nutritional strategies are needed to limit muscle wasting and to improve muscle mass recovery in such situations. The present review discusses mechanisms involved in muscle atrophy following disuse and during recovery and emphasises the effect of age in these mechanisms. In addition, the efficiency of nutritional strategies proposed to limit muscle mass loss during disuse and to improve protein gain during recovery (leucine supplementation, whey proteins, antioxidants and anti-inflammatory compounds, energy intake) is also discussed.
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Impaired recovery of dysferlin-null skeletal muscle after contraction-induced injury in vivo. Neuroreport 2008; 19:1579-84. [PMID: 18815587 DOI: 10.1097/wnr.0b013e328311ca35] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The protein, dysferlin, mediates sarcolemmal repair in vitro, implicating defective membrane repair in dysferlinopathies. To study the role of dysferlin in vivo, we assessed contractile function, sarcolemmal integrity, and myogenesis before and after injury from large-strain lengthening contractions in dysferlin-null and control mice. We report that dysferlin-null muscles produce higher contractile torque, and are equally susceptible to initial injury but recover from injury more slowly. Two weeks after injury, control muscles retain fluorescein dextran and do not show myogenesis. Dysferlin-null muscles do not retain fluorescein dextran, and show necrosis followed by myogenesis. Our data indicate that recovery of control muscles from injury primarily involves sarcolemmal repair whereas recovery of dysferlin-null muscles primarily involves myogenesis without repair and long-term survival of myofibers.
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Tidball JG, Wehling-Henricks M. Macrophages promote muscle membrane repair and muscle fibre growth and regeneration during modified muscle loading in mice in vivo. J Physiol 2006; 578:327-36. [PMID: 17038433 PMCID: PMC2075127 DOI: 10.1113/jphysiol.2006.118265] [Citation(s) in RCA: 276] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Muscle injury or modified muscle use can stimulate muscle invasion by leucocytes that have the potential to increase tissue damage or promote tissue growth and repair. In the present investigation, we examined the role of macrophages in muscle injury, repair and regeneration during modified muscle loading. Weight-bearing was removed from the hindlimbs of mice for 10 days followed by reloading through normal ambulation. During the unloading period, soleus muscle fibre cross-section decreased by 38%. Prior to the onset of reloading, mice received a series of intraperitoneal injections of anti-F4/80, which binds a mouse macrophage surface antigen. Although anti-F4/80 injections did not affect macrophage numbers in soleus muscles at 2 days of reloading, macrophages were reduced by 86% at 4 days of reloading. Muscle membrane lysis during the reloading period did not differ at 2 days of reloading between anti-F4/80-treated mice and mice that received isotype control antibody. However, control animals showed large decreases in the number of fibres with membrane lesions at 4 days of reloading, but this membrane repair did not occur in macrophage-depleted mice. Macrophage-depletion also reduced muscle regeneration (indicated by central nucleation) and satellite cell differentiation (indicated by reductions in MyoD-expressing satellite cells) and prevented growth of muscle fibres that normally occurred in control animals between days 2 and 4 of reloading. These findings collectively show that macrophages play a significant role in muscle fibre membrane repair, regeneration and growth during increased muscle use after a period of atrophy.
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Affiliation(s)
- James G Tidball
- Department of Physiological Science, 5833 Life Science Building, University of California, Los Angeles, CA 90095, USA.
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Baker BA, Mercer RR, Geronilla KB, Kashon ML, Miller GR, Cutlip RG. Stereological analysis of muscle morphology following exposure to repetitive stretch-shortening cycles in a rat model. Appl Physiol Nutr Metab 2006; 31:167-79. [PMID: 16604135 DOI: 10.1139/h05-009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Repetitive motion is one risk factor associated with contraction-induced muscle injury, which leads to skeletal muscle degeneration, inflammation, and dysfunction. Since current methods are unable to quantify the acute degenerative and inflammatory responses of muscle tissue concurrently, the purpose of this study was to quantify the temporal myofiber response after exposure to injurious stretch-shortening cycles (SSCs) using a standardized stereological technique. Functional testing was performed on the ankle dorsiflexor muscles of Sprague-Dawley rats in vivo. Rats were anesthetized and exposed to 15 sets of 10 SSCs. Control rats were exposed to 15 sets of single isometric contractions of the same stimulation duration. Changes in muscle morphometry were assessed at 0.5, 24, 48, 72, and 240 h post-exposure to quantify the degree of myofiber degeneration and inflammation in the tibialis anterior muscle from each group. There was an increase in the volume density and average thickness of degenerating myofibers over time in the muscle collected from rats exposed to SSCs (p < 0.0001) that was significantly greater than in muscle exposed to isometric contractions at 24, 48, and 72 h post-exposure (p = 0.003). The volume density of degenerative myofibers was associated with functional deficits at 48 h. Stereological quantification of degenerative myofibers and interstitial space changes were associated with functional defects 48-72 h after SSC-induced injury, thus demonstrating stereology is an accurate measure of SSC-induced skeletal muscle injury.
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Affiliation(s)
- Brent A Baker
- National Institute for Occupational Safety and Health, Morgantown, VA 26505, USA
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9
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Flück M, Schmutz S, Wittwer M, Hoppeler H, Desplanches D. Transcriptional reprogramming during reloading of atrophied rat soleus muscle. Am J Physiol Regul Integr Comp Physiol 2005; 289:R4-14. [PMID: 15956763 DOI: 10.1152/ajpregu.00833.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The hypothesis was tested that differential, coregulated transcriptional adaptations of various cellular pathways would occur early with increased mechanical loading of atrophied skeletal muscle and relate to concurrent damage of muscle fibers. Atrophy and slow-to-fast fiber transformation of rat soleus muscle was provoked by 14 days of hindlimb suspension (HS). Subsequent reloading of hindlimbs caused a fourfold increase in the percentage of muscle fibers, demonstrating endomysial tenascin-C staining. Five days after reloading, when 10% of the fibers were damaged, the normal muscle weight and slow-type fiber percentage were reestablished. Microarray analysis revealed major, biphasic patterns of gene expressional alterations with reloading that distinguish between treatments and gene ontologies. Transcript levels of factors involved in protein synthesis and certain proteasomal mRNAs were increased after 1 day of reloading and correlated to the percentage of fibers surrounded by tenascin-C. By contrast, levels of gene messages for fatty acid transporters, respiratory chain constituents, and voltage-gated cation channels were transiently reduced after 1 day of muscle loading and associated with the number of damaged fibers and the regain in muscle weight. This coregulation points toward important retooling of oxidative metabolism and the T- and SR-tubular systems with rebuilding of slow fibers. The observations demonstrate that early nuclear reprogramming with reloading of atrophic soleus muscle is coordinated and links to the processes involved in mechanical damage and regeneration of muscle fibers.
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Affiliation(s)
- Martin Flück
- Department of Anatomy, University of Bern, Baltzerstr. 2, 3000 Bern 9, Switzerland.
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Flück M, Chiquet M, Schmutz S, Mayet-Sornay MH, Desplanches D. Reloading of atrophied rat soleus muscle induces tenascin-C expression around damaged muscle fibers. Am J Physiol Regul Integr Comp Physiol 2003; 284:R792-801. [PMID: 12571079 DOI: 10.1152/ajpregu.00060.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hypothesis was tested that mechanical loading, induced by hindlimb suspension and subsequent reloading, affects expression of the basement membrane components tenascin-C and fibronectin in the belly portion of rat soleus muscle. One day of reloading, but not the previous 14 days of hindlimb suspension, led to ectopic accumulation of tenascin-C and an increase of fibronectin in the endomysium of a proportion (8 and 15%) of muscle fibers. Large increases of tenascin-C (40-fold) and fibronectin (7-fold) mRNA within 1 day of reloading indicates the involvement of pretranslational mechanisms in tenascin-C and fibronectin accumulation. The endomysial accumulation of tenascin-C was maintained up to 14 days of reloading and was strongly associated with centrally nucleated fibers. The observations demonstrate that an unaccustomed increase of rat soleus muscle loading causes modification of the basement membrane of damaged muscle fibers through ectopic endomysial expression of tenascin-C.
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Affiliation(s)
- Martin Flück
- M. E. Müller-Institute for Biomechanics, Department of Anatomy, University of Bern, 3000 Bern 9, Switzerland.
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11
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Provenzano PP, Martinez DA, Grindeland RE, Dwyer KW, Turner J, Vailas AC, Vanderby R. Hindlimb unloading alters ligament healing. J Appl Physiol (1985) 2003; 94:314-24. [PMID: 12391134 DOI: 10.1152/japplphysiol.00340.2002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the hypothesis that hindlimb unloading inhibits healing in fibrous connective tissue such as ligament. Male rats were assigned to 3- and 7-wk treatment groups with three subgroups each: sham control, ambulatory healing, and hindlimb-suspended healing. Ambulatory and suspended animals underwent surgical rupture of their medial collateral ligaments, whereas sham surgeries were performed on control animals. After 3 or 7 wk, mechanical and/or morphological properties were measured in ligament, muscle, and bone. During mechanical testing, most suspended ligaments failed in the scar region, indicating the greatest impairment was to ligament and not to bone-ligament insertion. Ligament testing revealed significant reductions in maximum force, ultimate stress, elastic modulus, and low-load properties in suspended animals. In addition, femoral mineral density, femoral strength, gastrocnemius mass, and tibialis anterior mass were significantly reduced. Microscopy revealed abnormal scar formation and cell distribution in suspended ligaments with extracellular matrix discontinuities and voids between misaligned, but well-formed, collagen fiber bundles. Hence, stress levels from ambulation appear unnecessary for formation of fiber bundles yet required for collagen to form structurally competent continuous fibers. Results support our hypothesis that hindlimb unloading impairs healing of fibrous connective tissue. In addition, this study provides compelling morphological evidence explaining the altered structure-function relationship in load-deprived healing connective tissue.
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Affiliation(s)
- Paolo P Provenzano
- Orthopedic Research Laboratories, Department of Orthopedics and Rehabilitation, University of Wisconsin, Madison 53792-3228, USA
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Totsuka T, Watanabe K, Uramoto I, Sakuma K, Mizutani T. Muscular dystrophy: centronucleation may reflect a compensatory activation of defective myonuclei. J Biomed Sci 2000; 5:54-61. [PMID: 9570514 DOI: 10.1007/bf02253356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Muscular dystrophy has long been believed to be characterized by degeneration and abortive regeneration of muscle fibers (the muscle degeneration theory), but unfortunately its pathogenesis is still unclear and an effective treatment has yet to be developed. As a challenge to the theory, we have proposed an alternative muscle-defective-growth theory and a further bone muscle growth imbalance hypothesis supposing possible defects in bone-growth-dependent muscle growth based on our findings in hereditary dystrophic dy mice (C57BL/6J dy/dy). This review presents some new insights into the pathogenesis of the disease along with our hypothesis, focusing on the physiological meaning of centronucleation, one of the major pathological changes commonly observed in dystrophic muscles of man and experimental animals.
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Affiliation(s)
- T Totsuka
- Department of Physiology, Aichi Prefectural Institute for Developmental Research, Kasugai, Japan
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Michael K. Relationship of skeletal muscle atrophy to functional status: a systematic research review. Biol Res Nurs 2000; 2:117-31. [PMID: 11337817 DOI: 10.1177/109980040000200205] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the realm of muscle atrophy research, many studies address minute details of molecular function but few examine the effects of atrophy in terms of mobility, strength, endurance, and performance of activities of daily living. The relationship between impairment and functional limitation is the focus of this research review. A wide array of studies constitute this area of inquiry, including investigations as diverse and widely disparate as molecular chemistry and space travel and populations as different as rats, healthy young men, and elderly women. Thirty-four studies were selected based on their fit with the Enabling-Disabling Model. Three paradigms of atrophy and function emerged. Adaptation reflects the plastic nature of muscle when placed under certain conditions, ranging from disuse to high-resistance exercise. Injury/loss describes damage to muscle tissue from ischemia, medications, or reloading or reperfusion trauma. Also in this category is the loss of muscle that is seen with aging. Integrity relates to the muscle's tendency to protect itself and maintain structural adjacencies and cellular proportions. Based on the 3 muscle research paradigms, the relationship of muscle atrophy to function is portrayed as a bidirectional interaction wherein form and function have an influence on each other by way of physical changes, including those of adaptation, injury/loss, or integrity. A conceptual model is constructed to reflect this relationship.
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Affiliation(s)
- K Michael
- Johns Hopkins Bayview Medical Center, Baltimore, MD, USA
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Cros N, Muller J, Bouju S, Piétu G, Jacquet C, Léger JJ, Marini JF, Dechesne CA. Upregulation of M-creatine kinase and glyceraldehyde3-phosphate dehydrogenase: two markers of muscle disuse. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R308-16. [PMID: 9950906 DOI: 10.1152/ajpregu.1999.276.2.r308] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle disuse induces substantial alterations in the highly plastic skeletal muscle tissues, which occur especially in antigravity slow muscles. We differentially screened a muscle cDNA array to identify modifications in gene profile expression induced in slow rat soleus muscle mechanically unloaded by hindlimb suspension as a model for muscle disuse. This study focused on muscle creatine kinase mRNA and protein and glyceraldehyde-3-phosphate dehydrogenase mRNA, which were found to be upregulated in unweighted muscles. These upregulations were analyzed over a 4-wk time course of hindlimb suspension and compared with variations in myosin heavy chain (MHC) isoforms while specifically focusing on type IIx MHC mRNA and protein. The two metabolic marker upregulations clearly preceded IIx MHC contractile protein upregulation. Muscle creatine kinase upregulation was shown to be an excellent, and the earliest, marker of muscle disuse at mRNA and protein levels.
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Affiliation(s)
- N Cros
- Institut National de la Santé et de la Recherche Médicale U 300, Faculté Pharmacie, 34060 Montpellier cedex 01, France
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