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Winther JB, Morgen JJ, Skov M, Broch-Lips MG, Nielsen OB, Overgaard K, Pedersen TH. Role of recovery of acetylcholine release in compromised neuromuscular junction function. Neuromuscul Disord 2024; 36:48-59. [PMID: 38359767 DOI: 10.1016/j.nmd.2024.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/17/2023] [Accepted: 01/22/2024] [Indexed: 02/17/2024]
Abstract
Everyday physical activities, such as walking, are enabled by repeated skeletal muscle contractions and require a well-functioning neuromuscular transmission. In myasthenic disorders, activities of daily living are debilitated by a compromised neuromuscular transmission leading to muscle weakness and fatiguability in patients. To enable physical activity, acetylcholine (ACh) is released repeatedly from the motor nerve, however, the role of the nerve terminals' capacity to sustain ACh release to support repetitive contractions under compromised neuromuscular transmission remains unclear. To explore this, we studied synaptic and contractile function during repeated contractions in healthy rat skeletal muscles under conditions of pharmacological induced compromised neuromuscular transmission. Using recordings of endplate potentials, compound muscle action potential (CMAP) and force production in isolated skeletal muscles and living, anesthetized animals, we found that force and CMAP were markedly reduced by even very light activity performed up to 5 s prior to contraction showing that recovery of ACh release was insufficient to maintain synaptic transmission strength. Our results suggest that the timing of depletion and restoration of ACh release may impact clinical signs of weakness and fatigability in patients with impaired neuromuscular transmission and affect the sensitivity of electromyographic recordings in the clinic.
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Affiliation(s)
| | | | - Martin Skov
- NMD Pharma A/S, Palle Juul-Jensens Blvd. 82, 8200 Aarhus N, Denmark
| | | | - Ole Bækgaard Nielsen
- Department of Public Health, Aarhus University, Bartholins Allé 2, 8000 Aarhus C, Denmark
| | - Kristian Overgaard
- Department of Public Health, Aarhus University, Bartholins Allé 2, 8000 Aarhus C, Denmark
| | - Thomas Holm Pedersen
- NMD Pharma A/S, Palle Juul-Jensens Blvd. 82, 8200 Aarhus N, Denmark; Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000 Aarhus C, Denmark.
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Thomsen JLS, Vinge L, Harbo T, Andersen H. A population-based follow-up study of maximal muscle strength and mobility in patients with myasthenia gravis. Neuromuscul Disord 2022; 32:305-312. [DOI: 10.1016/j.nmd.2022.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 01/23/2022] [Accepted: 02/15/2022] [Indexed: 10/19/2022]
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Thomsen JLS, Vinge L, Harbo T, Andersen H. Gender differences in clinical outcomes in myasthenia gravis: A prospective cohort study. Muscle Nerve 2021; 64:538-544. [PMID: 34036597 DOI: 10.1002/mus.27331] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 01/08/2023]
Abstract
INTRODUCTION/AIMS It is uncertain whether clinical outcomes differ between male and female patients with myasthenia gravis (MG) while receiving standard clinical care. METHODS In a prospective cohort study of 107 patients with MG receiving standard of care from 2012 to 2019, the Quantitative MG (QMG), the MG Composite (MGC), the MG Activities of Daily Living (MG-ADL), and the MG Quality of Life 15-Items (QOL15) were determined. Clinical outcomes were analyzed in relation to gender. RESULTS Mean follow-up time was 4.8 (±0.4) y, and 70 patients completed all follow-up assessments. Patients improved on all clinical scores: QMG -1.8 (P < .001), MGC -1.5 (P < .001), MG-ADL -1.3 (P < .001), and QOL15 -3.0 (P < .001). Females improved less than males on the QMG (P = .01), MGC (P < .001), MG-ADL (P = .006), and QOL15 (P < .001) independent of potential confounders. Males had moderate to strong correlations between changes in all clinical scales (r range 0.52 to 0.73), whereas females had weak correlations between changes in the QMG and MG-ADL (r = 0.13), the QMG and QOL15 (r = 0.27), the MGC and MG-ADL (r = 0.21), the MGC and QOL15 (r = 0.00), and the MG-ADL and QOL15 (r = 0.31). DISCUSSION Females improved less compared to males on objective and patient-reported outcomes. Moreover, females improved more on objective measures than on patient-reported outcomes. These gender differences should receive attention in clinical care and in the design of future trials.
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Affiliation(s)
- Jan L S Thomsen
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark.,Department of Neurology, Aalborg University Hospital, Aalborg, Denmark
| | - Lotte Vinge
- Department of Neurology, Aalborg University Hospital, Aalborg, Denmark
| | - Thomas Harbo
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Henning Andersen
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
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Burns TM. Estimating and managing fatigue for our patients: Are we measuring up? Muscle Nerve 2018. [DOI: 10.1002/mus.26125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ted M. Burns
- University of Virginia, Department of NeurologyCharlottesville Virginia USA
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Guan Y, Lv F, Meng Y, Ma D, Xu X, Song Y, Wang O, Jiang Y, Xia W, Xing X, Zhang J, Li M. Association between bone mineral density, muscle strength, and vitamin D status in patients with myasthenia gravis: a cross-sectional study. Osteoporos Int 2017; 28:2383-2390. [PMID: 28439619 DOI: 10.1007/s00198-017-4041-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/04/2017] [Indexed: 12/18/2022]
Abstract
UNLABELLED Myasthenia gravis (MG) patients had low proximal hip BMD, which could be explained by reduced muscle strength, elevated bone resorption markers, vitamin D deficiency, and increased PTH levels in those with MG compared to controls. INTRODUCTION Muscle strength is closely correlated with bone mineral density (BMD) and vitamin D status. Here, we evaluated muscle strength, BMD, and vitamin D status in a large sample of Chinese patients with MG. METHODS In this cross-sectional survey, 86 patients with MG without glucocorticoid treatment and 86 healthy controls were included. Serum levels of 25-hydroxyvitamin D [25OHD], parathyroid hormone (PTH), bone turnover markers (BTMs), and BMD were measured and compared between the two groups. Grip strength and one-leg standing time (OLST) were also assessed in MG patients. RESULTS Low grip strength and short OLST were found in 11 (12.8%) and 12 (14.0%) MG patients, respectively. There were 3 (3.5%) MG patients with low bone mass for chronological age. Serum beta C-terminal telopeptide and PTH levels were higher (p < 0.001 and p = 0.001, respectively), and BMD at the femoral neck and trochanter were lower in MG patients (p < 0.001 and p < 0.001, respectively) compared to healthy controls. In patients with MG, grip strength was positively correlated with BMD. Serum 25OHD levels were lower in MG patients than in healthy controls (17.36 ± 6.64 vs. 22.11 ± 7.28 ng/ml, p < 0.001). CONCLUSION Grip strength was positively correlated with BMD in Chinese patients with MG. MG patients tended to have low proximal hip BMD, which may partially be explained by reduced muscle strength, vitamin D deficiency, increased PTH levels, and elevated bone resorption markers compared to controls.
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Affiliation(s)
- Y Guan
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | - F Lv
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - Y Meng
- Department of Pathology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | - D Ma
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - X Xu
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - Y Song
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - O Wang
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - Y Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - W Xia
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - X Xing
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China
| | - J Zhang
- Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | - M Li
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health; Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Dongcheng District, Beijing, 100730, China.
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Rahbek MA, Mikkelsen EE, Overgaard K, Vinge L, Andersen H, Dalgas U. Exercise in myasthenia gravis: A feasibility study of aerobic and resistance training. Muscle Nerve 2017; 56:700-709. [PMID: 28085204 DOI: 10.1002/mus.25552] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 12/21/2016] [Accepted: 12/28/2016] [Indexed: 12/11/2022]
Abstract
INTRODUCTION It has not been established whether progressive resistance training (PRT) and aerobic training (AT) are feasible and efficient in myasthenia gravis (MG). METHODS Fifteen subjects with generalized MG (Myasthenia Gravis Foundation of America (MGFA) clinical classification II-IV) were randomly assigned to 20 training sessions during 8 weeks of either PRT or AT. Feasibility was evaluated based on adherence, drop-out rate, adverse events, and Quantitative Myasthenia Gravis (QMG) score. RESULTS Twelve subjects (MGFA II, n = 11; MGFA III, n=1) completed the intervention with a mean adherence of 95 % ± 8. One dropout (PRT) could potentially be related to PRT. Both groups reported adverse events, including bulbar symptoms (n = 2) and increased fatigue (n = 3), but no change in QMG score was observed in either group. The PRT group showed increases in maximal strength and functional capacity. CONCLUSIONS Eight weeks of moderate to high intensity AT and PRT were feasible for most patients with mild MG. Maximal strength and functional capacity increased in the PRT group. Muscle Nerve 56: 700-709, 2017.
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Affiliation(s)
- Martin Amadeus Rahbek
- Section for Sport Science, Department of Public Health, Aarhus University, Denmark, Dalgas Avenue 4, 8000, Aarhus C, Denmark
| | - Erik Elgaard Mikkelsen
- Section for Sport Science, Department of Public Health, Aarhus University, Denmark, Dalgas Avenue 4, 8000, Aarhus C, Denmark
| | - Kristian Overgaard
- Section for Sport Science, Department of Public Health, Aarhus University, Denmark, Dalgas Avenue 4, 8000, Aarhus C, Denmark
| | - Lotte Vinge
- Department of Neurology, Aarhus University Hospital, Noerrebrogade, 44, 8000 Aarhus C, Denmark
| | - Henning Andersen
- Department of Neurology, Aarhus University Hospital, Noerrebrogade, 44, 8000 Aarhus C, Denmark
| | - Ulrik Dalgas
- Section for Sport Science, Department of Public Health, Aarhus University, Denmark, Dalgas Avenue 4, 8000, Aarhus C, Denmark
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Jordan B, Mehl T, Schweden TL, Menge U, Zierz S. Assessment of physical fatigability and fatigue perception in myasthenia gravis. Muscle Nerve 2017; 55:657-663. [DOI: 10.1002/mus.25386] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/14/2016] [Accepted: 08/18/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Berit Jordan
- Department of Neurology; Martin Luther University Halle; Ernst-Grube-Strasse 40 06120 Halle Germany
| | - Theresa Mehl
- Department of Neurology; Martin Luther University Halle; Ernst-Grube-Strasse 40 06120 Halle Germany
| | - Tabea L.K. Schweden
- Institute of Psychology, Martin Luther University Halle; Halle/Saale Germany
| | - Uwe Menge
- Institute of Psychology, Martin Luther University Halle; Halle/Saale Germany
| | - Stephan Zierz
- Department of Neurology; Martin Luther University Halle; Ernst-Grube-Strasse 40 06120 Halle Germany
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