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Pratt SJP, Shah SB, Ward CW, Kerr JP, Stains JP, Lovering RM. Recovery of altered neuromuscular junction morphology and muscle function in mdx mice after injury. Cell Mol Life Sci 2014; 72:153-64. [PMID: 24947322 PMCID: PMC4282693 DOI: 10.1007/s00018-014-1663-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/14/2014] [Accepted: 06/02/2014] [Indexed: 12/02/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a devastating neuromuscular disease in which weakness, increased susceptibility to muscle injury, and inadequate repair underlie the pathology. While most attention has focused within the muscle fiber, we recently demonstrated significant alterations in the neuromuscular junction (NMJ) morphology and resulting neuromuscular transmission failure (NTF) 24 h after injury in mdx mice (murine model for DMD). Here we determine the contribution of NMJ morphology and NTF to the recovery of muscle contractile function post-injury. NMJ morphology and NTF rates were assessed day 0 (immediately after injury) and days 1, 7, 14 and 21 after quadriceps injury. Eccentric injury of the quadriceps resulted in a significant loss of maximal torque in both WT (39 ± 6 %) and mdx (76 ± 8 %) with a full recovery in WT by day 7 and in mdx by day 21. Post-injury alterations in NMJ morphology and NTF were found only in mdx, were limited to days 0 and 1, and were independent of changes in MuSK or AChR expression. Such early changes at the NMJ after injury are consistent with mechanical disruption rather than newly forming NMJs. Furthermore, we show that the dense microtubule network that underlies the NMJ is significantly reduced and disorganized in mdx compared to WT. These structural changes at the NMJ may play a role in the increased NMJ disruption and the exaggerated loss of nerve-evoked muscle force seen after injury to dystrophic muscles.
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Affiliation(s)
- Stephen J. P. Pratt
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn St. AHB, Room 540, Baltimore, MD 21201 USA
| | - Sameer B. Shah
- Department of Orthopaedic Surgery and Bioengineering, University of California, San Diego, USA
| | | | - Jaclyn P. Kerr
- Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
| | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn St. AHB, Room 540, Baltimore, MD 21201 USA
| | - Richard M. Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn St. AHB, Room 540, Baltimore, MD 21201 USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
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Wokke B, van den Bergen J, Versluis M, Niks E, Milles J, Webb A, van Zwet E, Aartsma-Rus A, Verschuuren J, Kan H. Quantitative MRI and strength measurements in the assessment of muscle quality in Duchenne muscular dystrophy. Neuromuscul Disord 2014; 24:409-16. [DOI: 10.1016/j.nmd.2014.01.015] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 01/25/2014] [Accepted: 01/31/2014] [Indexed: 10/25/2022]
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Lott DJ, Forbes SC, Mathur S, Germain SA, Senesac CR, Lee Sweeney H, Walter GA, Vandenborne K. Assessment of intramuscular lipid and metabolites of the lower leg using magnetic resonance spectroscopy in boys with Duchenne muscular dystrophy. Neuromuscul Disord 2014; 24:574-82. [PMID: 24798221 DOI: 10.1016/j.nmd.2014.03.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 03/24/2014] [Accepted: 03/28/2014] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to use proton magnetic resonance spectroscopy to assess intramuscular lipid and metabolites of lower leg muscles in boys with Duchenne muscular dystrophy (DMD) and determine its relationship with strength and functional ability. Spectroscopic measurements were obtained from four muscles of the lower leg in 25 boys with DMD (9.2±3.1 years) and 10 healthy boys (10.2±2.6 years). Lipid fractions and metabolite concentrations were also determined. Muscle strength, a timed functional test, and the Modified Brooke Lower Extremity Functional Scale were also determined. Lipid fractions were higher (p<0.01) for the DMD group than healthy subjects for all muscles, and lipid fraction was found to be greater in the older DMD boys. The peroneal muscle demonstrated a significant difference in lipid fraction in all DMD age groups. Lipid fractions in all muscles correlated with functional measures (r=0.52-0.70, p<0.001), with smaller inverse correlations with the strength measure (r=-0.36 to -0.56, p<0.05). These findings provide quantifiable information regarding intramuscular lipid and metabolite levels of different muscles across various age groups in boys with DMD and may be used in determining the effect of interventions in future clinical trials.
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Affiliation(s)
- Donovan J Lott
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
| | - Sean C Forbes
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Sunita Mathur
- Department of Physical Therapy, University of Toronto, Toronto, Ontario, Canada
| | - Sean A Germain
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA
| | - Claudia R Senesac
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - H Lee Sweeney
- Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Glenn A Walter
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, USA
| | - Krista Vandenborne
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
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Bendixen RM, Lott DJ, Senesac C, Mathur S, Vandenborne K. Participation in daily life activities and its relationship to strength and functional measures in boys with Duchenne muscular dystrophy. Disabil Rehabil 2014; 36:1918-23. [PMID: 24499260 DOI: 10.3109/09638288.2014.883444] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE While most studies of Duchenne muscular dystrophy (DMD) have focused on physical impairment, there is a need to explore how impairment impacts real-life experiences in order to provide intervention strategies focused on participation. Objectives were: (1) to investigate the domains of participation in a sample of boys with DMD; (2) to compare a younger (<10 years) and older (≥10 years) group of boys with DMD with regard to participation; (3) to investigate strength and timed functional tests in a sample of boys with DMD; (4) to compare a younger (<10 years) and older (≥10 years) group of boys with DMD with regard to strength and timed functional tests; and (5) to explore associations between participation and strength and timed functional tests for our DMD cohorts. METHODS This cross-sectional study included 60 boys with DMD (mean 9.3 years ± 0.3). Boys completed strength testing, timed functional tests, the Children's Assessment of Participation and Enjoyment and the ACTIVLIM. Independent samples t-tests were used to test for differences in all measures between our younger and older cohorts; Spearman's (rank) correlation was used to assess relationships between participation and strength and time functional tests. RESULTS Significant differences were found between our younger and older boys with DMD in the areas of recreational (p < 0.01), social (p < 0.001), and skill-based activities (p < 0.05), as well as with whom and where the activities were performed (p < 0.05 and 0.001, respectively). Older boys with DMD report lower levels of participation in these areas, as well as less engagement in activities with individuals other than family members and less participation outside of the home. Lower levels of strength and slower rates of functional performance correlate with participation in fewer physical activities for our younger cohort and fewer physical and social activities for our older cohort. CONCLUSIONS Strength and function relate to the variability and type of activities in which boys with DMD participate. A key finding is the significant decline in social activities and community-based engagement as the boys with DMD age. The ultimate goal of an intervention is for our children to be as actively engaged in life as they desire. This requires addressing participation when measuring outcomes in order to more fully understand limitations and provide appropriate strategies for continued participation for boys and their families. IMPLICATIONS FOR REHABILITATION Duchenne muscular dystrophy is a devastating progressive neuromuscular disorder that leads to significant strength and functional limitations, which affect physical and social participation for these boys. The ability to move beyond clinically-based outcomes and assess and monitor a child's daily activities through participation measures may provide information for therapeutic interventions. Rehabilitation specialists have a role as advocates for social and community engagement for children with physical limitations. Providing families with information on community-based opportunities, and the strategies and environmental modifications available may increase social participation for our youth growing up with a neuromuscular disorder.
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Affiliation(s)
- Roxanna M Bendixen
- Department of Occupational Therapy, University of Pittsburgh , Pittsburgh, PA , USA
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Baltgalvis KA, Call JA, Cochrane GD, Laker RC, Yan Z, Lowe DA. Exercise training improves plantar flexor muscle function in mdx mice. Med Sci Sports Exerc 2013; 44:1671-9. [PMID: 22460476 DOI: 10.1249/mss.0b013e31825703f0] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
PURPOSE We tested the hypothesis that low-intensity exercise in mdx mice improves plantar flexor muscle contractile function, resistance to fatigue, and mitochondrial adaptations without exacerbating muscular dystrophy. METHODS We subjected mdx mice to 12 wk of voluntary low-resistance wheel running (Run, n = 17) or normal cage activities (sedentary (Sed), n = 16) followed by in vivo analyses for plantar flexor torque generation and fatigue resistance or running capacity on a treadmill. Gastrocnemius muscles were further evaluated for exercise-induced mitochondrial adaptations and fiber type distribution and central nuclei. t-tests were used to determine differences between the Sed and Run groups. RESULTS Plantar flexor submaximal isometric torques and maximal isometric torque at multiple ankle joint angles and resistance to fatigue were greater in Run compared with Sed mdx mice (P G 0.05). Citrate synthase and A-hydroxyacyl-CoA dehydrogenase enzyme activities and cytochrome c oxidase IV protein expression in gastrocnemius muscles were greater in Run than in Sed mdx mice(P e 0.04), along with a trend of fiber type transformation from Type IIb to Type IIx fibers. Exercise training in mdx mice did not elevate serum creatine kinase levels but led to a significant reduction of centrally nucleated myofibers. CONCLUSIONS Voluntary low-resistance wheel running in mdx mice can result in skeletal muscle adaptation, leading to improved contractile function and reduced fatigability,with no indication that exercise was detrimental. This study supports the need for further investigation of low-intensity exercise as an early therapeutic intervention in ambulatory boys with Duchenne muscular dystrophy.
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Forbes SC, Walter GA, Rooney WD, Wang DJ, DeVos S, Pollaro J, Triplett W, Lott DJ, Willcocks RJ, Senesac C, Daniels MJ, Byrne BJ, Russman B, Finkel RS, Meyer JS, Sweeney HL, Vandenborne K. Skeletal muscles of ambulant children with Duchenne muscular dystrophy: validation of multicenter study of evaluation with MR imaging and MR spectroscopy. Radiology 2013; 269:198-207. [PMID: 23696684 DOI: 10.1148/radiol.13121948] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To validate a multicenter protocol that examines lower extremity skeletal muscles of children with Duchenne muscular dystrophy (DMD) by using magnetic resonance (MR) imaging and MR spectroscopy in terms of reproducibility of these measurements within and across centers. MATERIALS AND METHODS This HIPAA-compliant study was approved by the institutional review boards of all participating centers, and informed consent was obtained from each participant or a guardian. Standardized procedures with MR operator training and quality assurance assessments were implemented, and data were acquired at three centers by using different 3-T MR imaging instruments. Measures of maximal cross-sectional area (CSAmax), transverse relaxation time constant (T2), and lipid fraction were compared among centers in two-compartment coaxial phantoms and in two unaffected adult subjects who visited each center. Also, repeat MR measures were acquired twice on separate days in 30 boys with DMD (10 per center) and 10 unaffected boys. Coefficients of variation (CVs) were computed to examine the repeated-measure variabilities within and across centers. RESULTS CSAmax, T2 from MR imaging and MR spectroscopy, and lipid fraction were consistent across centers in the phantom (CV, <3%) and in the adult subjects who traveled to each site (CV, 2%-7%). High day-to-day reproducibility in MR measures was observed in boys with DMD (CSAmax, CV = 3.7% [25th percentile, 1.3%; 75th percentile, 5.1%]; contractile area, CV = 4.2% [25th percentile, 0.8%; 75th percentile, 4.9%]; MR imaging T2, CV = 3.1% [25th percentile, 1.2%; 75th percentile, 4.7%]; MR spectroscopy T2, CV = 3.9% [25th percentile, 1.5%; 75th percentile, 5.1%]; and lipid fraction, CV = 4.7% [25th percentile, 1.0%; 75th percentile, 5.3%]). CONCLUSION The MR protocol implemented in this multicenter study achieved highly reproducible measures of lower extremity muscles across centers and from day to day in ambulatory boys with DMD.
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Affiliation(s)
- Sean C Forbes
- Department of Physical Therapy, Department of Physiology and Functional Genomics, and Department of Pediatrics and Molecular Genetics and Microbiology, Powell Gene Therapy Center, University of Florida, Box 100154, UFHSC, Gainesville, FL 32610; Advanced Imaging Research Center, Oregon Health and Science University, Portland, Ore; Division of Neurology and Department of Radiology, the Children's Hospital of Philadelphia, Philadelphia, Pa; Section of Integrative Biology, Division of Statistics and Scientific Computation, the University of Texas at Austin, Austin, Tex; Departments of Pediatrics and Neurology, Oregon Health and Science University, Shriners Hospital for Children, Portland, Ore; Nemours Children's Hospital, University of Central Florida College of Medicine, Orlando, Fla
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Arpan I, Forbes SC, Lott DJ, Senesac CR, Daniels MJ, Triplett WT, Deol JK, Sweeney HL, Walter GA, Vandenborne K. T₂ mapping provides multiple approaches for the characterization of muscle involvement in neuromuscular diseases: a cross-sectional study of lower leg muscles in 5-15-year-old boys with Duchenne muscular dystrophy. NMR IN BIOMEDICINE 2013; 26:320-8. [PMID: 23044995 PMCID: PMC3573223 DOI: 10.1002/nbm.2851] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 07/14/2012] [Accepted: 08/03/2012] [Indexed: 05/15/2023]
Abstract
Skeletal muscles of children with Duchenne muscular dystrophy (DMD) show enhanced susceptibility to damage and progressive lipid infiltration, which contribute to an increase in the MR proton transverse relaxation time (T₂). Therefore, the examination of T₂ changes in individual muscles may be useful for the monitoring of disease progression in DMD. In this study, we used the mean T₂, percentage of elevated pixels and T₂ heterogeneity to assess changes in the composition of dystrophic muscles. In addition, we used fat saturation to distinguish T₂ changes caused by edema and inflammation from fat infiltration in muscles. Thirty subjects with DMD and 15 age-matched controls underwent T₂ -weighted imaging of their lower leg using a 3-T MR system. T₂ maps were developed and four lower leg muscles were manually traced (soleus, medial gastrocnemius, peroneal and tibialis anterior). The mean T₂ of the traced regions of interest, width of the T₂ histograms and percentage of elevated pixels were calculated. We found that, even in young children with DMD, lower leg muscles showed elevated mean T₂, were more heterogeneous and had a greater percentage of elevated pixels than in controls. T₂ measures decreased with fat saturation, but were still higher (P < 0.05) in dystrophic muscles than in controls. Further, T₂ measures showed positive correlations with timed functional tests (r = 0.23-0.79). The elevated T₂ measures with and without fat saturation at all ages of DMD examined (5-15 years) compared with unaffected controls indicate that the dystrophic muscles have increased regions of damage, edema and fat infiltration. This study shows that T₂ mapping provides multiple approaches that can be used effectively to characterize muscle tissue in children with DMD, even in the early stages of the disease. Therefore, T₂ mapping may prove to be clinically useful in the monitoring of muscle changes caused by the disease process or by therapeutic interventions in DMD.
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Affiliation(s)
- Ishu Arpan
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Sean C Forbes
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Donovan J Lott
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Claudia R Senesac
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Michael J Daniels
- Department of Statistics; University of Florida, Gainesville, Florida
| | - William T Triplett
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida
| | - Jasjit K Deol
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - H Lee Sweeney
- Department of Physiology; University of Pennsylvania, Philadelphia, Pennsylvania
| | - Glenn A Walter
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Krista Vandenborne
- Department of Physical Therapy, University of Florida, Gainesville, Florida
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Cheuy VA, Commean PK, Hastings MK, Mueller MJ. Reliability and validity of a MR-based volumetric analysis of the intrinsic foot muscles. J Magn Reson Imaging 2013; 38:1083-93. [PMID: 23450691 DOI: 10.1002/jmri.24069] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 01/11/2013] [Indexed: 12/22/2022] Open
Abstract
PURPOSE To describe a semi-automated program that will segment subcutaneous fat, muscle, and adipose tissue in the foot using MR imaging, determine the reliability of the program between and within raters, and determine the validity of the program using MR phantoms. MATERIALS AND METHODS MR images were acquired from 19 subjects with and without diabetes and peripheral neuropathy. Two raters segmented and measured volumes from single MR slices at the forefoot, midfoot, and hindfoot at two different times. Intra- and inter-rater correlation coefficients were determined. Muscle and fat MR phantoms of known volumes were measured by the program. RESULTS Most ICC reliability values were over 0.950. Validity estimates comparing MR estimates and known volumes resulted in r(2) values above 0.970 for all phantoms. The root mean square error was less than 5% for all phantoms. CONCLUSION Subcutaneous fat, lean muscle, and adipose tissue volumes in the foot can be quantified in a reliable and valid way. This program can be applied in future studies investigating the relationship of these foot structures to functions in important pathologies, including the neuropathic foot or other musculoskeletal problems.
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Affiliation(s)
- Victor A Cheuy
- Applied Biomechanics Laboratory, Movement Science Program, and Program in Physical Therapy, Washington University School of Medicine, St. Louis, Missouri, USA
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Forbes SC, Lott DJ, Finkel RS, Senesac C, Byrne BJ, Sweeney HL, Walter GA, Vandenborne K. MRI/MRS evaluation of a female carrier of Duchenne muscular dystrophy. Neuromuscul Disord 2013; 22 Suppl 2:S111-21. [PMID: 22980762 DOI: 10.1016/j.nmd.2012.05.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 04/03/2012] [Indexed: 12/20/2022]
Abstract
The purpose of this study was to evaluate skeletal muscle composition of lower extremity muscles in a manifesting female carrier of Duchenne muscular dystrophy (MFC(DMD)) using magnetic resonance imaging (MRI) and spectroscopy (MRS). MRI/MRS was performed on the lower extremities and heart of a MFC(DMD) (47 years, 51 kg) on four occasions within 21 months and in a control subject. Heterogeneity and asymmetry among muscles in the MFC(DMD) was observed in lipid fraction and mean transverse relaxation time (T(2)) of lower extremity muscles with some muscles presenting as unaffected (e.g., rectus femoris) and others showing substantial deterioration and lipid infiltration (e.g., vasti muscles). There was an association of abnormal MRI findings and strength and motor function. Over the 21 months a small decrease in CSA(max) and increase in lipid fraction and T(2) was observed in the MFC(DMD) in some muscles. In summary, this MFC(DMD) revealed significant imaging evidence of pathologic heterogeneity among muscles. Furthermore, this study shows the feasibility of combining various quantitative MRI and MRS approaches to monitor skeletal muscle involvement.
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Affiliation(s)
- Sean C Forbes
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, United States
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A computerized MRI biomarker quantification scheme for a canine model of Duchenne muscular dystrophy. Int J Comput Assist Radiol Surg 2013; 8:763-74. [PMID: 23299128 DOI: 10.1007/s11548-012-0810-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 12/26/2012] [Indexed: 10/27/2022]
Abstract
PURPOSE Golden retriever muscular dystrophy (GRMD) is a widely used canine model of Duchenne muscular dystrophy (DMD). Recent studies have shown that magnetic resonance imaging (MRI) can be used to non-invasively detect consistent changes in both DMD and GRMD. In this paper, we propose a semiautomated system to quantify MRI biomarkers of GRMD. METHODS Our system was applied to a database of 45 MRI scans from 8 normal and 10 GRMD dogs in a longitudinal natural history study. We first segmented six proximal pelvic limb muscles using a semiautomated full muscle segmentation method. We then performed preprocessing, including intensity inhomogeneity correction, spatial registration of different image sequences, intensity calibration of T2-weighted and T2-weighted fat-suppressed images, and calculation of MRI biomarker maps. Finally, for each of the segmented muscles, we automatically measured MRI biomarkers of muscle volume, intensity statistics over MRI biomarker maps, and statistical image texture features. RESULTS The muscle volume and the mean intensities in T2 value, fat, and water maps showed group differences between normal and GRMD dogs. For the statistical texture biomarkers, both the histogram and run-length matrix features showed obvious group differences between normal and GRMD dogs. The full muscle segmentation showed significantly less error and variability in the proposed biomarkers when compared to the standard, limited muscle range segmentation. CONCLUSION The experimental results demonstrated that this quantification tool could reliably quantify MRI biomarkers in GRMD dogs, suggesting that it would also be useful for quantifying disease progression and measuring therapeutic effect in DMD patients.
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Pratt SJP, Shah SB, Ward CW, Inacio MP, Stains JP, Lovering RM. Effects of in vivo injury on the neuromuscular junction in healthy and dystrophic muscles. J Physiol 2012; 591:559-70. [PMID: 23109110 DOI: 10.1113/jphysiol.2012.241679] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The most common and severe form of muscular dystrophy is Duchenne muscular dystrophy (DMD), a disorder caused by the absence of dystrophin, a structural protein found on the cytoplasmic surface of the sarcolemma of striated muscle fibres. Considerable attention has been dedicated to studying myofibre damage and muscle plasticity, but there is little information to determine if damage from contraction-induced injury occurs at or near the nerve terminal axon. We used α-bungarotoxin to compare neuromuscular junction (NMJ) morphology in healthy (wild-type, WT) and dystrophic (mdx) mouse quadriceps muscles and evaluated transcript levels of the post-synaptic muscle-specific kinase signalling complex. Our focus was to study changes in NMJs after injury induced with an established in vivo animal injury model. Neuromuscular transmission, electromyography (EMG), and NMJ morphology were assessed 24 h after injury. In non-injured muscle, muscle-specific kinase expression was significantly decreased in mdx compared to WT. Injury resulted in a significant loss of maximal torque in WT (39 ± 6%) and mdx (76 ± 8%) quadriceps, but significant changes in NMJ morphology, neuromuscular transmission and EMG data were found only in mdx following injury. Compared with WT mice, motor end-plates of mdx mice demonstrated less continuous morphology, more disperse acetylcholine receptor aggregates and increased number of individual acetylcholine receptor clusters, an effect that was exacerbated following injury. Neuromuscular transmission failure increased and the EMG measures decreased after injury in mdx mice only. The data show that eccentric contraction-induced injury causes morphological and functional changes to the NMJs in mdx skeletal muscle, which may play a role in excitation-contraction coupling failure and progression of the dystrophic process.
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Affiliation(s)
- Stephen J P Pratt
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Ragonesi D, Agrawal SK, Sample W, Rahman T. Quantifying anti-gravity torques for the design of a powered exoskeleton. IEEE Trans Neural Syst Rehabil Eng 2012; 21:283-8. [PMID: 23096118 DOI: 10.1109/tnsre.2012.2222047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Designing an upper extremity exoskeleton for people with arm weakness requires knowledge of the joint torques due to gravity and joint stiffness, as well as, active residual force capabilities of users. The objective of this research paper is to describe the characteristics of the upper limb of children with upper limb impairment. This paper describes the experimental measurements of the torque on the upper limb due to gravity and joint stiffness of three groups of subjects: able-bodied adults, able-bodied children, and children with neuromuscular disabilities. The experiment involves moving the arm to various positions in the sagittal plane and measuring the resultant force at the forearm. This force is then converted to torques at the elbow and shoulder. These data are compared to a two-link lumped mass model based on anthropomorphic data. Results show that the torques based on anthropometry deviate from experimentally measured torques as the arm goes through the range. Subjects with disabilities also maximally pushed and pulled against the force sensor to measure maximum strength as a function of arm orientation. For all subjects, the maximum voluntary applied torque at the shoulder and elbow in the sagittal plane was found to be lower than gravity torques throughout the disabled subjects' range of motion. This experiment informs designers of upper limb orthoses on the contribution of passive human joint torques due to gravity and joint stiffness and the strength capability of targeted users.
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Affiliation(s)
- Daniel Ragonesi
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA.
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Lerario A, Bonfiglio S, Sormani M, Tettamanti A, Marktel S, Napolitano S, Previtali S, Scarlato M, Natali-Sora M, Mercuri E, Bresolin N, Mongini T, Comi G, Gatti R, Ciceri F, Cossu G, Torrente Y. Quantitative muscle strength assessment in duchenne muscular dystrophy: longitudinal study and correlation with functional measures. BMC Neurol 2012; 12:91. [PMID: 22974002 PMCID: PMC3482602 DOI: 10.1186/1471-2377-12-91] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 08/16/2012] [Indexed: 11/17/2022] Open
Abstract
Background The aim of this study was to perform a longitudinal assessment using Quantitative Muscle Testing (QMT) in a cohort of ambulant boys affected by Duchenne muscular dystrophy (DMD) and to correlate the results of QMT with functional measures. This study is to date the most thorough long-term evaluation of QMT in a cohort of DMD patients correlated with other measures, such as the North Star Ambulatory Assessment (NSAA) or thee 6-min walk test (6MWT). Methods This is a single centre, prospective, non-randomised, study assessing QMT using the Kin Com® 125 machine in a study cohort of 28 ambulant DMD boys, aged 5 to 12 years. This cohort was assessed longitudinally over a 12 months period of time with 3 monthly assessments for QMT and with assessment of functional abilities, using the NSAA and the 6MWT at baseline and at 12 months only. QMT was also used in a control group of 13 healthy age-matched boys examined at baseline and at 12 months. Results There was an increase in QMT over 12 months in boys below the age of 7.5 years while in boys above the age of 7.5 years, QMT showed a significant decrease. All the average one-year changes were significantly different than those experienced by healthy controls. We also found a good correlation between quantitative tests and the other measures that was more obvious in the stronger children. Conclusion Our longitudinal data using QMT in a cohort of DMD patients suggest that this could be used as an additional tool to monitor changes, providing additional information on segmental strength.
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Affiliation(s)
- Alberto Lerario
- Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Centro Dino Ferrari, IRCCS Istituto Auxologico Italiano, Università di Milano, Fondazione, Ospedale Maggiore Policlinico di Milano, Italy
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Ragonesi D, Agrawal S, Sample W, Rahman T. Quantifying anti-gravity torques in the design of a powered exoskeleton. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:7458-61. [PMID: 22256063 DOI: 10.1109/iembs.2011.6091749] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Designing an upper extremity exoskeleton for people with arm weakness requires knowledge of the passive and active residual force capabilities of users. This paper experimentally measures the passive gravitational torques of 3 groups of subjects: able-bodied adults, able bodied children, and children with neurological disabilities. The experiment involves moving the arm to various positions in the sagittal plane and measuring the gravitational force at the wrist. This force is then converted to static gravitational torques at the elbow and shoulder. Data are compared between look-up table data based on anthropometry and empirical data. Results show that the look-up torques deviate from experimentally measured torques as the arm reaches up and down. This experiment informs designers of Upper Limb orthoses on the contribution of passive human joint torques.
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Affiliation(s)
- Daniel Ragonesi
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA.
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Finanger EL, Russman B, Forbes SC, Rooney WD, Walter GA, Vandenborne K. Use of skeletal muscle MRI in diagnosis and monitoring disease progression in Duchenne muscular dystrophy. Phys Med Rehabil Clin N Am 2011; 23:1-10, ix. [PMID: 22239869 DOI: 10.1016/j.pmr.2011.11.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Studies have shown promise in using various approaches of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy to evaluate skeletal muscle involvement in Duchenne muscular dystrophy. However, these studies have mainly been performed using a cross-sectional design, and the correlation of these MRI changes with disease progression and disease severity has not been fully elucidated. Overall, skeletal muscle MRI is a powerful and sensitive technique in the evaluation of muscle disease, and its use as a biomarker for disease progression or therapeutic response in clinical trials deserves further study.
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Affiliation(s)
- Erika L Finanger
- Department of Pediatrics, Oregon Health and Science University, Portland, OR 97239, USA.
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Commean PK, Tuttle LJ, Hastings MK, Strube MJ, Mueller MJ. Magnetic resonance imaging measurement reproducibility for calf muscle and adipose tissue volume. J Magn Reson Imaging 2011; 34:1285-94. [PMID: 21964677 DOI: 10.1002/jmri.22791] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 07/29/2011] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To describe a new semiautomated method for segmenting and measuring the volume of the muscle, bone, and adipose (subcutaneous and intermuscular) tissue in calf muscle compartments using magnetic resonance (MR) images and determine the intrarater and interrater reproducibility of the measures. MATERIALS AND METHODS Proton-density weighted MR images were acquired from the right calf of 21 subjects. Three raters segmented and measured the volumes of bones, adipose tissue, and five individual muscle compartments. Two raters repeated the segmentations. The intra- and interrater reproducibility of the measures (intraclass correlation coefficients; ICC) were determined using generalizability theory. RESULTS All ICC values were greater than 0.96. The average standard error of the mean (SEM) of all measures was 1.21 cm(3) and none were greater than 2.3 cm(3) . Essentially all variation (≥97% for all measures) was due to subject differences, indicating low error in the measurements. CONCLUSION The volumetric measurements for the bones, adipose tissue, and muscle in each of the compartments using MRI were highly reproducible. MRI can provide quantitative, reproducible volumetric measures of bone, adipose tissue, and individual muscle compartments in the calf. We believe these methods can be used to quantify specific muscle or adipose volumetric measures for other clinical or research purposes.
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Affiliation(s)
- Paul K Commean
- Electronic Radiology Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA.
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67
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Current world literature. Curr Opin Neurol 2011; 24:511-6. [PMID: 21900773 DOI: 10.1097/wco.0b013e32834be5c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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68
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Akima H, Lott D, Senesac C, Deol J, Germain S, Arpan I, Bendixen R, Lee Sweeney H, Walter G, Vandenborne K. Relationships of thigh muscle contractile and non-contractile tissue with function, strength, and age in boys with Duchenne muscular dystrophy. Neuromuscul Disord 2011; 22:16-25. [PMID: 21807516 DOI: 10.1016/j.nmd.2011.06.750] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 05/16/2011] [Accepted: 06/27/2011] [Indexed: 10/17/2022]
Abstract
The purpose of this study was to assess the contractile and non-contractile content in thigh muscles of patients with Duchenne muscular dystrophy (DMD) and determine the relationship with functional abilities. Magnetic resonance images of the thigh were acquired in 28 boys with DMD and 10 unaffected boys. Muscle strength, timed functional tests, and the Brookes Lower Extremity scale were also assessed. Non-contractile content in the DMD group was significantly greater than in the control group for six muscles, including rectus femoris, biceps femoris-long head and adductor magnus. Non-contractile content in the total thigh musculature assessed by MRI correlated with the Brookes scale (r(s)=0.75) and supine-up test (r(s)=0.68), as well as other functional measures. An age-related specific torque increase was observed in the control group (r(s)=0.96), but not the DMD (r(s)=0.06). These findings demonstrate that MRI measures of contractile and non-contractile content can provide important information about disease progression in DMD.
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Affiliation(s)
- Hiroshi Akima
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, USA.
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