Abstract Anastomotic strictures and leaks are severe complications following esophageal atresia (EA) repair. We hypothesized that esophageal injections of botulinum toxin type A (BTX-A) could mitigate these complications through muscle relaxation. This randomized, controlled, blinded animal trial evaluated the feasibility and safety of a long- and short-gap porcine EA model. Furthermore, the effect of BTX-A as a surgical adjunct on anastomotic outcomes were exploratory assessed. Twenty-four animals received BTX-A or saline pre- or intraoperative to a three- or one-centimeter esophageal resection and primary anastomosis. The primary feasibility endpoint was animal completion rate at postoperative day 14, while stricture severity was the primary exploratory outcome. Secondary exploratory outcomes were anastomotic leakage frequency, and biomechanical and histological characteristics. Animal completion rate was 62.5% (15/24). There was no difference in stricture severity between the intervention and control groups (Esophageal Anastomotic Stricture Index 0.41 [IQR 0.26–0.55] versus 0.35 [IQR 0.27–0.58]; p = 0.73). One animal in the control group suffered an anastomotic leak. Biomechanical properties and anastomotic healing did not differ. While the procedure was technically feasible, refinement is necessary to reduce attrition rate and establish a safe model for long-term evaluation. More studies are needed to determine whether BTX-A can provide a reduction in anastomotic complications.

Sporadic inclusion body myositis (sIBM) is a subgroup of idiopathic inflammatory myopathies characterised by progressive muscle weakness and skeletal muscle inflammation. Quantitative data on the myofibre morphology in sIBM remains scarce. Further, no previous study has examined fibre type association of satellite cells (SC), myonuclei number, macrophages, capillaries, and myonuclear domain (MD) in sIBM patients. Muscle biopsies from sIBM patients (n = 18) obtained previously (NCT02317094) were included in the analysis for fibre type-specific myofibre cross-sectional area (mCSA), SCs, myonuclei and macrophages, myonuclear domain, and capillarisation. mCSA (p < 0.001), peripheral myonuclei (p < 0.001) and MD (p = 0.005) were higher in association with type 1 (slow-twitch) than type 2 (fast-twitch) fibres. Conversely, quiescent SCs (p < 0.001), centrally placed myonuclei (p = 0.03), M1 macrophages (p < 0.002), M2 macrophages (p = 0.013) and capillaries (p < 0.001) were higher at type 2 fibres compared to type 1 fibres. In contrast, proliferating (Pax7+/Ki67+) SCs (p = 0.68) were similarly associated with each fibre type. Type 2 myofibres of late-phase sIBM patients showed marked signs of muscle atrophy (i.e. reduced mCSA) accompanied by higher numbers of associated quiescent SCs, centrally placed myonuclei, macrophages and capillaries compared to type 1 fibres. In contrast, type 1 fibres were suffering from pathological enlargement with larger MDs as well as fewer nuclei and capillaries per area when compared with type 2 fibres. More research is needed to examine to which extent different therapeutic interventions including targeted exercise might alleviate these fibre type-specific characteristics and countermeasure their consequences in impaired functional performance.

Background: Reduced muscle endurance and strength are cardinal traits in patients with myositis[1]. These traits are associated with reduced quality of life[2], thus an increase in endurance and strength could potentially lead to improved quality of life. Our randomised controlled trial (RCT) (NCT04486261) investigated the effects of 16 weeks of progressively adjusted high-intensity resistance training on the quality of life in patients with myositis. Increases in quality of life, muscle strength and muscle endurance were observed immediately following the 16-week intervention period for participants allocated to high-intensity resistance exercise compared to non-exercising controls. However, it is unknown to which extent these positive changes are sustained over time. Objectives: To investigate if the effects of 16 weeks of high-intensity resistance exercise persist at the 1-year follow-up in patients with myositis. Methods: In the RCT, 32 patients with myositis were allocated to 16 weeks of high-intensity resistance training (HRT, n=15) or 16 weeks of care-as-usual (CON, n=17). In the present follow-up study, outcomes were compared from baseline (week 0) to 1-year follow-up (week 52). Following the 16 weeks of intervention, both groups were given training programs and encouraged to exercise. Twenty-seven patients completed follow-up (HRT, n=13; CON, n=14) and were included in the per protocol analysis. The primary outcome was quality of life (Short Form 36, physical component summary). Secondary outcomes included functional capacity (incl. functional index 3, 30-s sit-to-stand, timed-up-&-go, 2-minute walk test and handgrip strength), body composition by DEXA (height-adjusted appendicular muscle and fat mass), self-reported levels of physical activity and measures of disease activity and damage (incl. health assessment questionnaire, manual muscle testing 8, physician and patient global activity, and physician and patient global damage). Paired t-testing was used to perform within-group comparisons between baseline and 1-year follow-up. Further, a linear model was used to evaluate between-group differences over time. Results: HRT demonstrated increases in physical component summary (p=0.005), functional index 3 (p=0.004), 30-s sit-to-stand (p=0.008), timed-up-&-go (p<0.001) and handgrip strength (p=0.023) at 1-year follow-up compared to baseline, while 30-s sit-to-stand (p<0.001) and 2-minute walk test (p<0.001) were improved in CON (Table 1). Reduced levels of physical activity were observed in HRT (p<0.001) (Table 1). In disease activity and damage measures, only manual muscle testing 8 increased for HRT (p=0.020). In CON, manual muscle testing 8 (p=0.020), physician (p=0.003) and patient global damage (p=0.020) were improved at 1-year follow-up (Table 2). With the exception of the height-adjusted appendicular fat mass (p=0.049), no between-group differences over time were observed (Table 1 & Table 2). Conclusion: Myositis patients allocated to 16 weeks of high-intensity resistance training showed sustained within-group improvements in physical quality of life, functional capacity and muscle strength at 1-year follow-up. However, these sustained improvements were not superior to care-as-usual, as the group also improved in some functional parameters and muscle strength at 1-year follow-up. No signs of increased disease activity or damage were observed at 1-year follow-up. REFERENCES: [1] Lundberg IE, Fujimoto M, Vencovsky J, et al. Idiopathic inflammatory myopathies. Nat Rev Dis Primers. 2021;7(1):86. Published 2021 Dec 2. doi:10.1038/s41572-021-00321-x. [2] Poulsen KB, Alexanderson H, Dalgård C, Jacobsen S, Weile L, Diederichsen LP. Quality of life correlates with muscle strength in patients with dermato- or polymyositis. Clin Rheumatol. 2017;36(10):2289-2295. doi:10.1007/s10067-017-3706-6. Acknowledgements: Physiotherapist, PhD student Charlotte Grønset performed all physical function tests and her help was an indispensable for the completion of the current study. Disclosure of Interests: None declared.

OBJECTIVE:To investigate the potential associations between functional capacity, muscle strength, body composition, and disease-related measures and quality of life in patients with myositis.METHODS:Baseline measures of functional capacity (functional index 3 (FI3), 2-minute walk test (2MWT), timed up and go (TUG) and 30-s sit-to-stand (30-STS)), muscle strength (incl. leg and handgrip strength), maximal leg extensor power, body composition (appendicular lean mass, fat percentage/mass) and disease-related measures (disease activity & damage core sets) were examined for their associations with quality of life (physical- and mental component summary scores, Short Form 36 questionnaire (SF-36)) by means of Spearman's correlation analysis.RESULTS:A total of 32 patients with myositis were included. Positive correlations between SF-36 physical component summary score (PCS) and FI3, 30-STS, TUG, 2MWT, leg extensor power, leg strength, bench press strength, and handgrip strength were observed. In contrast, fat percentage and fat mass correlated negatively with PCS. In disease-related measures, Extramuscular global assessment, health assessment questionnaire, physician global damage, and patient global damage scores were negatively associated with SF-36 PCS. No correlations to the mental component summary score of SF-36 were observed.CONCLUSION:All measures of functional capacity were positively related to the SF-36 physical component summary score, indicating higher functional capacity positively affects quality of life in patients with myositis. Health assessment questionnaire and patient global damage scores demonstrated the strongest correlations with SF-36 physical component summary scores, further supporting these patient-reported outcomes as viable monitoring tools in patients with myositis.

The success of rotator cuff tendon repair relies on both tendon healing and muscle recovery. The objective of this descriptive study was to investigate the regenerative potential of the supraspinatus muscle in rotator cuff tear conditions by quantifying the expression of Pax7, MyoD, and myogenin, basic factors that regulate myogenesis. Muscle biopsies were collected from thirty-three patients aged 34 to 73 years who underwent surgery for a rotator cuff tear affecting the supraspinatus muscle. Among these patients, twenty-seven percent were women, and the age of the lesions ranged from 2 to 72 months post-initial trauma. Biopsies were harvested from the supraspinatus muscle at the end closest to the tendon, and control biopsies were harvested from the ipsilateral deltoid muscle. The densities of immunohistochemically stained Pax7+, MyoD+, and myogenin+ nuclei/mm2 were used to estimate the myogenic potential of the muscle. Adjustments were made for patient age and lesion age. We found increased density of MyoD+ and myogenin+ cells in supraspinatus muscles compared to deltoid muscles (p < 0.001 and p = 0.003, respectively). Regression analyses that combined the density of positive nuclei with patient age showed a continuous increase in Pax7 with age but also a reduction of MyoD and myogenin in older patients. When combined with lesion age, there was a decline in the density of all myogenic markers after an initial rise. Pax7 density continued to be higher in supraspinatus compared to the deltoid muscle, but the density of MyoD and myogenin terminally dropped to a density lower than in the deltoid. Our findings suggest that the supraspinatus muscle in tear conditions showed signs of initial activation of muscle regeneration. When compared to the unaffected deltoid muscle, an apparent reduction in capacity to progress to full muscle fiber maturity was also demonstrated. This pattern of inhibited myogenesis seemed to increase with both patient age and lesion age. Our results on muscle regenerative capacity indicate that younger patients with rotator cuff tears have better chances of muscle recovery and may benefit from early surgical reconstruction.

Disease causing variants in the Ryanodine receptor 1 (RYR1) gene are a common cause for congenital myopathy and for malignant hyperthermia susceptibility. We report a 17 year old boy with congenital muscle weakness progressing to a myasthenia like myopathy with muscle weakness, fatigability, ptosis, and ophthalmoplegia. Muscle biopsy showed predominance and atrophy of type 1 fibers. Whole-exome trio sequencing revealed three variants in the RYR1-gene in the patient: c.6721C > T,p.(Arg2241*) and c.2122G > A,p.(Asp708Asn) in cis position, and the c.325C > T,p.(Arg109Trp) variant in trans. Treatment with pyridostigmine improved symp-toms. This case supports that a myasthenia like phenotype is part of the phenotypic spectrum of RYR1 related disorders, and that treatment with pyridostigmine can be beneficial for patients with this phenotype.

Objective: To describe neurophysiological abnormalities cin Long COVID and correlate quantitative elec-tromyography (qEMG) and single fiber EMG (sfEMG) results to clinical scores and histopathology. Methods: 84 patients with non-improving musculoskeletal Long COVID symptoms were examined with qEMG and sfEMG. Muscle biopsies were taken in a subgroup.Results: Mean motor unit potential (MUP) duration was decreased in >= 1 muscles in 52 % of the patients. Mean jitter was increased in 17 % of the patients in tibialis anterior and 25 % in extensor digitorum com-munis. Increased jitter was seen with or without myopathic qEMG. Low quality of life score correlated with higher jitter values but not with qEMG measures. In addition to our previously published mitochon-drial changes, inflammation, and capillary injury, we show now in muscle biopsies damage of terminal nerves and motor endplate with abundant basal lamina material. At the endplate, axons were present but no vesicle containing terminals. The post-synaptic cleft in areas appeared atrophic with short clefts and coarse crests.Conclusions: Myopathic changes are common in Long COVID. sfEMG abnormality is less common but may correlate with clinical scores. sfEMG changes may be due to motor endplate pathology. Significance: These findings may indicate a muscle pathophysiology behind fatigue in Long COVID.(c) 2023 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Radiostereometric analysis (RSA) studies have shown that the continuous migration of tibial components is predictive of aseptic loosening following total knee arthroplasty (TKA). In the present study, we investigated whether accurate sizing and placement of tibial components are related to the degree of implant migration as measured with use of RSA. Methods:A total of 111 patients who underwent TKA surgery with a cementless tibial component were followed for a period of 2 years postoperatively, during which implant migration was assessed with use of RSA. RSA was performed within 7 days postoperatively and after 3, 6, 12, and 24 months. Postoperative radiographs were evaluated for component size and placement in the tibia. The evaluations were performed by experienced knee surgeons who were blinded to the migration data and clinical outcomes. A multivariable linear regression analysis was conducted. Results:Continuous implant migration (i.e., migration occurring between 12 and 24 months postoperatively) had a negative association with tibial component size (coefficient [B], -0.2; 95% confidence interval [CI], -0.33 to -0.08). Subsidence was associated with the absence of posterior cortical bone support (B, -0.7; 95% CI, -1.09 to -0.28), the absence of lateral cortical bone support (B, 0.8; 95% CI, 0.29 to 1.37), frontal-plane varus malalignment (B, 0.6; 95% CI, 0.12 to 1.16), and component undersizing (B, -0.4; 95% CI, -0.06 to -0.68). Posterior tilt was associated only with undersizing (B, 0.6; 95% CI, 0.27 to 1.11). Conclusions:Undersized cementless tibial components are at a higher risk for poor fixation with continuous migration following TKA. Therefore, a higher risk of aseptic loosening should be expected. Level of Evidence:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Background Idiopathic inflammatory myopathies – or briefly myositis – has cardinal traits of muscle weakness [1] and decreased muscle endurance [2] in addition to reduced quality of life (QoL) [3]. However, QoL is complex, and it is unclear which factors affect QoL in patients with myositis. Knowledge of these factors and potential associations to QoL is of importance for evoking changes to a better life for patients with myositis. Objectives To investigate the influence of functional capacity, muscle strength, body composition and disease activity and damage on QoL in patients with myositis. Methods Measures of functional capacity (functional index 3, 2-minute walk test, timed-up-and- go and 30-s sit-to-stand), muscle strength (5 repetitions maximum strength in leg press, bench press, cable row, knee extension, biceps curl and static handgrip strength; all expressed relative to body mass), leg extensor power (Nottingham Power Rig, relative to body mass), body composition (height adjusted appendicular lean mass and fat mass) and IMACS (International Myositis Assessment & Clinical Studies Group) disease activity and disease damage core set measures were analysed to investigate the impact on QoL (physical- and mental component summary in the Short Form 36 questionnaire (SF-36)). Results All functional capacity measures were positively correlated with the physical component summary (PCS); functional index 3 (r2=0.15, p=0.03), 2-minute walk test (r2=0.26, p=0.003), timed-up-and-go (r2=0.14, p=0.03) and 30-sit-to-stand performance (r2=0.15, p=0.03). Only leg press (r2=0.15, p=0.04) showed a positive correlation with PCS for measures of muscle strength and power. For body composition, height-adjusted fat mass correlated negatively with PCS (r2=0.20, p=0.01). Of the IMACS disease activity and disease damage core set measures, Health Assessment Questionnaire (r2=0.40, p=0.0001), Physician Global Assessment of Disease Damage (r2=0.44, p<0.001) and Patient Global Assessment of Disease Damage (r2=0.18, p=0.02) were negatively correlated with PCS. In contrast, none of the investigated outcome parameters were correlated with the mental component summary of SF-36. Conclusion In the present group of patients with myositis, functional capacity and muscle strength had positive associations with the physical component summary of the QoL, indicating that future interventions should be directed to improve these factors to ultimately improve QoL. The Health Assessment Questionnaire and Patient/Physician Global Assessment of Disease Damage revealed strong correlations with PCS, supporting that both patient-reported outcome measures (PROMS) and clinician-reported outcomes are highly relevant QoL-related monitoring parameters in patients with myositis. References [1]Amato AA, Greenberg SA. Inflammatory myopathies. Continuum (Minneap Minn). 2013;19(6 Muscle Disease):1615-1633. doi:10.1212/01.CON.0000440662.26427.bd[2]Alemo Munters L, Dastmalchi M, Katz A, et al. Improved exercise performance and increased aerobic capacity after endurance training of patients with stable polymyositis and dermatomyositis. Arthritis Res Ther. 2013;15(4):R83. Published 2013 Aug 13. doi:10.1186/ar4263[3]Poulsen KB, Alexanderson H, Dalgård C, Jacobsen S, Weile L, Diederichsen LP. Quality of life correlates with muscle strength in patients with dermato- or polymyositis. Clin Rheumatol. 2017;36(10):2289-2295. doi:10.1007/s10067-017-3706-6 Acknowledgements: NIL. Disclosure of Interests Kasper Yde Jensen: None declared, Per Aagaard: None declared, Charlotte Suetta: None declared, Jakob Nielsen: None declared, Henrik Daa Schrøder: None declared, Charlotte Grønset: None declared, Louise Pyndt Diederichsen Speakers bureau: Boehringer Ingelheim, Grant/research support from: Boehringer Ingelheim.

Supplementary Methods, Figures 1-10 from MMSET Is Highly Expressed and Associated with Aggressiveness in Neuroblastoma

to quantify stem cell markers Paired Box 7 (Pax7), Myoblast Determination Protein 1 (MyoD1) and myogenin (MyoG) as an expression of the regenerative potential of the supraspinatus (SS) muscle in RC tear conditions.

Background: Radiostereometric analysis (RSA) studies have shown that the continuous migration of tibial components is predictive of aseptic loosening following total knee arthroplasty (TKA). In the present study, we investigated whether accurate sizing and placement of tibial components are related to the degree of implant migration as measured with use of RSA. Methods: A total of 111 patients who underwent TKA surgery with a cementless tibial component were followed for a period of 2 years postoperatively, during which implant migration was assessed with use of RSA. RSA was performed within 7 days postoperatively and after 3, 6, 12, and 24 months. Postoperative radiographs were evaluated for component size and placement in the tibia. The evaluations were performed by experienced knee surgeons who were blinded to the migration data and clinical outcomes. A multivariable linear regression analysis was conducted. Results: Continuous implant migration (i.e., migration occurring between 12 and 24 months postoperatively) had a negative association with tibial component size (coefficient [B], −0.2; 95% confidence interval [CI], −0.33 to −0.08). Subsidence was associated with the absence of posterior cortical bone support (B, −0.7; 95% CI, −1.09 to −0.28), the absence of lateral cortical bone support (B, 0.8; 95% CI, 0.29 to 1.37), frontal-plane varus malalignment (B, 0.6; 95% CI, 0.12 to 1.16), and component undersizing (B, −0.4; 95% CI, −0.06 to −0.68). Posterior tilt was associated only with undersizing (B, 0.6; 95% CI, 0.27 to 1.11). Conclusions: Undersized cementless tibial components are at a higher risk for poor fixation with continuous migration following TKA. Therefore, a higher risk of aseptic loosening should be expected. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background Pathological mechanisms in the affected synovial joints in rheumatoid arthritis (RA) and factors contributing to synovial histological heterogeneity, which may impact treatment outcomes, remain largely unexplored at the protein level. Mapping the proteomic landscape of RA-affected synovial tissue (ST) and identifying determinants of synovial pathotypes could provide insights into RA's pathological mechanisms, identify new therapeutic targets, and pave the way for personalized medicine options. Objectives To map the proteomic landscape and dysregulated biological pathways in ST and plasma at multiple stages of RA. Through this investigation, the study also aims to identify the molecular and cellular determinants of synovial histological pathotypes in early untreated RA patients. Methods ST and matched plasma samples from patients with early untreated RA (ERA) (n = 20) and longstanding RA (LRA) (n = 20), as well as healthy controls (HC) (n = 16) were collected at baseline and at six months follow-up (RA patients only). ST biopsies were collected from the wrist via an ultrasound-guided synovial biopsy procedure (RA patients), or via arthroscopic guidance (HC). Samples were then characterized using discovery proteomics profiling. Comparisons were made between HC versus ERA or LRA at both timepoints, and proteins were regarded as differentially abundant at 5% FDR and a log2-fold change ±2.0 (ST proteins) or ±1.5 (plasma proteins). Next, the molecular and cellular determinants of synovial histological pathotypes were identified in untreated ERA patients by integrating the ST proteome, plasma proteome, Krenn synovitis score, number of circulating immune cells and scores of CD3 (T cells), CD20 (B cells), CD68 (Macrophages) and CD138 (Plasma cells) synovial immune infiltration. Results 335 plasma proteins and 3416 ST proteins were identified and quantified. Plasma proteins: CRP and SAA1 were overabundant in ERA compared to HC at baseline, but no proteins were differentially abundant in ERA compared to HC at follow-up (Figure 1 A-B). CRP was overabundant in LRA compared to HC at both timepoints (Figure 1 C-D). Synovial tissue proteins: In ERA patients 243 proteins were differentially abundant at baseline, but only 114 were differentially abundant at follow-up (Figure 1 E-F). In LRA patients, 216 and 284 proteins were differentially abundant at baseline and follow-up, respectively (Figure 1 G-H). Largely the same biological processes were dysregulated in ERA at baseline and in LRA at both timepoints. However, biological processes related to complement cascade, acute inflammatory response, scavenging of heme from plasma among others, tended to be less dysregulated in ERA patients at follow-up. Finally, data integration identified proteomic and cellular signatures underlying synovial pathotypes, that suggests the difference between lymphoid, myeloid, and fibroid pathotypes is a continuous spectrum that is linearly modellable. Proteins involved in negative regulation of: peptidase/protease activity, hemostasis and wound healing were underabundant in the lymphoid pathotype compared to the fibroid pathotype and to a lesser degree, the myeloid pathotype. Proteins that were involved in various aspects of antibody production were overabundant in the lymphoid pathotype compared to the fibroid pathotype and to a lesser degree, the myeloid pathotype. Conclusion The study revealed new insights into the proteomic landscape of the synovium in RA, elucidating the pathological mechanisms occurring in the synovium at different stages of disease. Additionally, the study identified a linear proteomic and cellular difference between the lymphoid, myeloid, and fibroid synovial pathotypes in untreated ERA patients, rather than distinct signatures for each pathotype. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests None Declared.Figure 1Comparison between plasma and synovial tissue proteomes of early untreated rheumatoid arthritis patients (ERA) or longstanding rheumatoid arthritis (LRA) at baseline or follow-up versus healthy controls.

Among post‐COVID‐19 symptoms, fatigue is reported as one of the most common, even after mild acute infection, and as the cause of fatigue, myopathy diagnosed by electromyography has been proposed in previous reports. This study aimed to explore the histopathological changes in patients with post‐COVID‐19 fatigue.

European Journal of NeurologyVolume 29, Issue 12 p. 3752-3753 LETTER TO THE EDITOR Reply to “Post-COVID myopathy” Eva K. Hejbøl, Eva K. Hejbøl Department of Pathology, Odense University Hospital, Odense, Denmark Department of Regional Health Research, University of Southern Denmark, Odense, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorThomas Harbo, Thomas Harbo Department of Neurology, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorJane Agergaard, Jane Agergaard Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorLars J. Østergaard, Lars J. Østergaard Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorHenning Andersen, Henning Andersen Department of Neurology, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorHenrik D. Schrøder, Henrik D. Schrøder Department of Pathology, Odense University Hospital, Odense, Denmark Department of Histopathology, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorHatice Tankisi, Corresponding Author Hatice Tankisi hatitank@rm.dk orcid.org/0000-0001-8495-9769 Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark Correspondence Hatice Tankisi, Department of Clinical Neurophysiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark. Email: hatitank@rm.dk Contribution: Conceptualization (lead), Writing - original draft (lead)Search for more papers by this author Eva K. Hejbøl, Eva K. Hejbøl Department of Pathology, Odense University Hospital, Odense, Denmark Department of Regional Health Research, University of Southern Denmark, Odense, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorThomas Harbo, Thomas Harbo Department of Neurology, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorJane Agergaard, Jane Agergaard Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorLars J. Østergaard, Lars J. Østergaard Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorHenning Andersen, Henning Andersen Department of Neurology, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorHenrik D. Schrøder, Henrik D. Schrøder Department of Pathology, Odense University Hospital, Odense, Denmark Department of Histopathology, Aarhus University Hospital, Aarhus, Denmark Contribution: Writing - review & editing (equal)Search for more papers by this authorHatice Tankisi, Corresponding Author Hatice Tankisi hatitank@rm.dk orcid.org/0000-0001-8495-9769 Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark Correspondence Hatice Tankisi, Department of Clinical Neurophysiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark. Email: hatitank@rm.dk Contribution: Conceptualization (lead), Writing - original draft (lead)Search for more papers by this author First published: 16 August 2022 https://doi.org/10.1111/ene.15525Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume29, Issue12December 2022Pages 3752-3753 RelatedInformation

Sporadic inclusion body myositis (sIBM) is characterised by skeletal muscle inflammation, progressive muscle loss and weakness, which is largely refractory to immunosuppressive treatment. Low-load blood-flow restricted (BFR) training has been shown to evoke gains in myofibre cross sectional area (mCSA) in healthy adults. This could partially be due to the activation and integration of muscle satellite cells (SC) resulting in myonuclei addition. Consequently, this study investigated the effect of 12-weeks lower limb low-load BFR resistance training in sIBM patients on SC and myonuclei content, myofibre size and capillarization. Muscle biopsies from sIBM patients randomised to 12-weeks of low-load BFR resistance training (n = 11) or non-exercising controls (CON) (n = 9) were analysed for SC and myonuclei content, myofibre size and capillarization using three-colour immunofluorescence microscopy and computerised quantification procedures. No between-group differences (time-by-group interactions) or within-groups changes were observed for resident SCs (Pax7(+)/Six1(+)), proliferating SCs (Pax7(+)/ Ki67(+)), myonuclei (Six1(+)), type 1 mCSA or capillary number (CD31(+)). However, a time-by-group interaction for type 2 mCSA was observed (p = 0.04). Satellite cell content, myonuclei number, mCSA and capillary density remained unaffected following 12-weeks low-load BFR resistance training, indicating limited myogenic capacity and satellite cell plasticity in long-term sIBM patients. (C) 2022 The Authors. Published by Elsevier B.V.