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Muscle spasticity after nervous system injuries and painful low back spasm affect more than 10% of global population. Current medications are of limited efficacy and cause neurological and cardiovascular side effects because they target upstream regulators of muscle contraction. Direct myosin inhibition could provide optimal muscle relaxation; however, targeting skeletal myosin is particularly challenging because of its similarity to the cardiac isoform. We identified a key residue difference between these myosin isoforms, located in the communication center of the functional regions, which allowed us to design a selective inhibitor, MPH-220. Mutagenic analysis and the atomic structure of MPH-220-bound skeletal muscle myosin confirmed the mechanism of specificity. Targeting skeletal muscle myosin by MPH-220 enabled muscle relaxation, in human and model systems, without cardiovascular side effects and improved spastic gait disorders after brain injury in a disease model. MPH-220 provides a potential nervous-system-independent option to treat spasticity and muscle stiffness.
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Músculo Esquelético/metabolismo , Miosinas de Músculo Esquelético/efeitos dos fármacos , Miosinas de Músculo Esquelético/genética , Adulto , Animais , Miosinas Cardíacas/genética , Miosinas Cardíacas/metabolismo , Linhagem Celular , Sistemas de Liberação de Medicamentos , Feminino , Humanos , Masculino , Camundongos , Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Espasticidade Muscular/genética , Espasticidade Muscular/fisiopatologia , Músculo Esquelético/fisiologia , Miosinas/efeitos dos fármacos , Miosinas/genética , Miosinas/metabolismo , Isoformas de Proteínas , Ratos , Ratos Wistar , Miosinas de Músculo Esquelético/metabolismoRESUMO
Proprioception - the sense of body position in space - is intimately linked to motor control. Here, we briefly review the current knowledge of the proprioceptive system and how advances in the genetic characterisation of proprioceptive sensory neurons in mice promise to dissect its role in health and disease.
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Propriocepção , Células Receptoras Sensoriais , Camundongos , Animais , Propriocepção/fisiologia , Células Receptoras Sensoriais/fisiologiaRESUMO
Hyaluronan (HA) plays well-recognized mechanical and biological roles in articular cartilage and synovial fluid, where it contributes to tissue structure and lubrication. An understanding of how HA contributes to the structure of other musculoskeletal tissues, including muscle, bone, tendon, and intervertebral discs, is growing. In addition, the use of HA-based therapies to restore damaged tissue is becoming more prevalent. Nevertheless, the relationship between biomechanical stimuli and HA synthesis, degradation, and signaling in musculoskeletal tissues remains understudied, limiting the utility of HA in regenerative medicine. In this review, we discuss the various roles and significance of endogenous HA in musculoskeletal tissues. We use what is known and unknown to motivate new lines of inquiry into HA biology within musculoskeletal tissues and in the mechanobiology governing HA metabolism by suggesting questions that remain regarding the relationship and interaction between biological and mechanical roles of HA in musculoskeletal health and disease.
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Ácido Hialurônico , Tendões , Ácido Hialurônico/química , Humanos , Animais , Fenômenos Biomecânicos , Tendões/fisiologia , Tendões/metabolismo , Cartilagem Articular/fisiologia , Cartilagem Articular/metabolismo , Transdução de Sinais , Osso e Ossos/metabolismo , Osso e Ossos/fisiologia , Líquido Sinovial/metabolismo , Líquido Sinovial/fisiologia , Músculo Esquelético/fisiologia , Músculo Esquelético/metabolismo , Sistema Musculoesquelético/metabolismo , Medicina Regenerativa/métodosRESUMO
BACKGROUND: The Ehlers-Danlos syndromes (EDS) are heritable disorders of connective tissue (HDCT), reclassified in the 2017 nosology into 13 subtypes. The genetic basis for hypermobile Ehlers-Danlos syndrome (hEDS) remains unknown. METHODS: Whole exome sequencing (WES) was undertaken on 174 EDS patients recruited from a national diagnostic service for complex EDS and a specialist clinic for hEDS. Patients had already undergone expert phenotyping, laboratory investigation and gene sequencing, but were without a genetic diagnosis. Filtered WES data were reviewed for genes underlying Mendelian disorders and loci reported in EDS linkage, transcriptome and genome-wide association studies (GWAS). A genetic burden analysis (Minor Allele Frequency (MAF) <0.05) incorporating 248 Avon Longitudinal Study of Parents and Children (ALSPAC) controls sequenced as part of the UK10K study was undertaken using TASER methodology. RESULTS: Heterozygous pathogenic (P) or likely pathogenic (LP) variants were identified in known EDS and Loeys-Dietz (LDS) genes. Multiple variants of uncertain significance where segregation and functional analysis may enable reclassification were found in genes associated with EDS, LDS, heritable thoracic aortic disease (HTAD), Mendelian disorders with EDS symptomatology and syndromes with EDS-like features. Genetic burden analysis revealed a number of novel loci, although none reached the threshold for genome-wide significance. Variants with biological plausibility were found in genes and pathways not currently associated with EDS or HTAD. CONCLUSIONS: We demonstrate the clinical utility of large panel-based sequencing and WES for patients with complex EDS in distinguishing rare EDS subtypes, LDS and related syndromes. Although many of the P and LP variants reported in this cohort would be identified with current panel testing, they were not at the time of this study, highlighting the use of extended panels and WES as a clinical tool for complex EDS. Our results are consistent with the complex genetic architecture of EDS and suggest a number of novel hEDS and HTAD candidate genes and pathways.
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Doenças do Tecido Conjuntivo , Síndrome de Ehlers-Danlos , Criança , Humanos , Estudo de Associação Genômica Ampla , Estudos Longitudinais , Síndrome de Ehlers-Danlos/diagnóstico , Síndrome de Ehlers-Danlos/genéticaRESUMO
BACKGROUND: Marfan syndrome (MFS) is a multisystem disease with a unique combination of skeletal, cardiovascular and ocular features. Geleophysic/acromicric dysplasias (GPHYSD/ACMICD), characterised by short stature and extremities, are described as 'the mirror image' of MFS. The numerous FBN1 pathogenic variants identified in MFS are located all along the gene and lead to the same final pathogenic sequence. Conversely, in GPHYSD/ACMICD, the 28 known heterozygous FBN1 pathogenic variants all affect exons 41-42 encoding TGFß-binding protein-like domain 5 (TB5). METHODS: Since 1996, more than 5000 consecutive probands have been referred nationwide to our laboratory for molecular diagnosis of suspected MFS. RESULTS: We identified five MFS probands carrying distinct heterozygous pathogenic in-frame variants affecting the TB5 domain of FBN1. The clinical data showed that the probands displayed a classical form of MFS. Strikingly, one missense variant affects an amino acid that was previously involved in GPHYSD. CONCLUSION: Surprisingly, pathogenic variants in the TB5 domain of FBN1 can lead to two opposite phenotypes: GPHYSD/ACMICD and MFS, suggesting the existence of different pathogenic sequences with the involvement of tissue specificity. Further functional studies are ongoing to determine the precise role of this domain in the physiopathology of each disease.
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Doenças do Desenvolvimento Ósseo , Deformidades Congênitas dos Membros , Síndrome de Marfan , Humanos , Doenças do Desenvolvimento Ósseo/genética , Fibrilina-1/genética , Síndrome de Marfan/genética , Síndrome de Marfan/patologia , MutaçãoRESUMO
The extracellular matrix (ECM) determines functional properties of connective tissues through structural components, such as collagens, elastic fibers, or proteoglycans. The ECM also instructs cell behavior through regulatory proteins, including proteases, growth factors, and matricellular proteins, which can be soluble or tethered to ECM scaffolds. The secreted a disintegrin and metalloproteinase with thrombospondin type 1 repeats/motifs-like (ADAMTSL) proteins constitute a family of regulatory ECM proteins that are related to ADAMTS proteases but lack their protease domains. In mammals, the ADAMTSL protein family comprises seven members, ADAMTSL1-6 and papilin. ADAMTSL orthologs are also present in the worm, Caenorhabditis elegans, and the fruit fly, Drosophila melanogaster. Like other matricellular proteins, ADAMTSL expression is characterized by tight spatiotemporal regulation during embryonic development and early postnatal growth and by cell type- and tissue-specific functional pleiotropy. Although largely quiescent during adult tissue homeostasis, reexpression of ADAMTSL proteins is frequently observed in the context of physiological and pathological tissue remodeling and during regeneration and repair after injury. The diverse functions of ADAMTSL proteins are further evident from disorders caused by mutations in individual ADAMTSL proteins, which can affect multiple organ systems. In addition, genome-wide association studies (GWAS) have linked single nucleotide polymorphisms (SNPs) in ADAMTSL genes to complex traits, such as lung function, asthma, height, body mass, fibrosis, or schizophrenia. In this review, we summarize the current knowledge about individual members of the ADAMTSL protein family and highlight recent mechanistic studies that began to elucidate their diverse functions.
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Drosophila melanogaster , Estudo de Associação Genômica Ampla , Feminino , Animais , Matriz Extracelular/genética , Proteínas ADAMTS/genética , Caenorhabditis elegans , Tecido Conjuntivo , MamíferosRESUMO
BACKGROUND: An increasing number of women are choosing mastectomy and subpectoral implant (SI) breast reconstruction over breast-conserving therapy (BCT). It is unclear to what extent these procedures differ in their effect on the pectoralis major (PM). The purpose of this study was to assess the impact of choosing BCT or SI breast reconstruction on PM function. METHODS: Ultrasound shear wave elastography images were acquired from the PM fiber regions and surface electromyography obtained activity from six shoulder muscles, while 14 BCT participants, 14 SI participants, and 14 age-matched controls remained at rest or generated submaximal shoulder torques. RESULTS: BCT and SI participants were significantly weaker in shoulder adduction, while BCT participants were also weaker in internal and external rotation (all p ≤ 0.003). PM function was altered following either BCT or SI. In all treatment groups, the clavicular fiber region contributed primarily to flexion, and the sternocostal primarily contributed to adduction. However, healthy participants utilized the clavicular region more during adduction and the sternocostal region more during flexion when compared to BCT or SI participants (all p ≤ 0.049). The still intact clavicular region increased its contributions to flexion torques in SI participants compared to controls (p = 0.016). Finally, BCT and SI participants compensated for changes in PM function using synergistic shoulder musculature. CONCLUSION: Both BCT and SI breast reconstruction result in significant long-term upper extremity strength deficits. Our results suggest changes to the underlying function of the PM and the adoption of unique but inadequate neuromuscular compensation strategies drive these deficits.
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BACKGROUND: Chronic liver diseases constitute a major global public health burden, posing a substantial threat to patients' daily lives and even survival due to the potential development of musculoskeletal disorders. Although the relationship between chronic liver diseases and musculoskeletal disorders has received extensive attention, their causal relationship has not been comprehensively and systematically investigated. METHODS: This study aimed to assess the causal relationships between viral hepatitis, primary biliary cholangitis, primary sclerosing cholangitis (PSC), liver cirrhosis, and hepatocellular carcinoma (HCC) with osteoporosis, osteoarthritis, and sarcopenia through bidirectional Mendelian randomization (MR) research. The traits related to osteoporosis and osteoarthritis included both overall and site-specific phenotypes, and the traits linked to sarcopenia involved indicators of muscle mass and function. Random-effect inverse-variance weighted (IVW), weighted median, MR-Egger, and Causal Analysis Using the Summary Effect Estimates were used to evaluate causal effects, with IVW being the main analysis method. To enhance robustness, sensitivity analyses were performed using Cochran's Q test, MR-Egger intercept, MR-PRESSO global test, funnel plots, leave-one-out analyses, and latent causal variable model. RESULTS: The forward MR analysis indicated that PSC can reduce forearm bone mineral density (beta = - 0.0454, 95% CI - 0.0798 to - 0.0110; P = 0.0098) and increase the risk of overall osteoarthritis (OR = 1.012, 95% CI 1.002-1.022; P = 0.0247), while HCC can decrease grip strength (beta = - 0.0053, 95% CI - 0.008 to - 0.0025; P = 0.0002). The reverse MR analysis did not find significant causal effects of musculoskeletal disorders on chronic liver diseases. Additionally, no heterogeneity or pleiotropy was detected. CONCLUSIONS: These findings corroborate the causal effects of PSC on osteoporosis and osteoarthritis, as well as the causal impact of HCC on sarcopenia. Thus, the implementation of comprehensive preventive measures is imperative for PSC and HCC patients to mitigate the risk of musculoskeletal disorders, ultimately improving their quality of life.
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Carcinoma Hepatocelular , Neoplasias Hepáticas , Doenças Musculoesqueléticas , Osteoartrite , Osteoporose , Sarcopenia , Humanos , Qualidade de Vida , Estudo de Associação Genômica AmplaRESUMO
OBJECTIVE: This study aimed to explore the specific function of M2 macrophages in intervertebral disc degeneration (IDD). METHODS: Intervertebral disc (IVD) samples from normal (n = 4) and IDD (n = 6) patients were collected, and the expression of M2-polarized macrophage marker, CD206, was investigated using immunohistochemical staining. Nucleus pulposus cells (NPCs) in a TNF-α environment were obtained, and a mouse caudal IVD puncture model was established. Mice with Rheb deletions, specifically in the myeloid lineage, were generated and subjected to surgery-induced IDD. IDD-induced damage and cell apoptosis were measured using histological scoring, X-ray imaging, immunohistochemical staining, and TdT-mediated dUTP nick end labeling (TUNEL) assay. Finally, mice and NPCs were treated with R-spondin-2 (Rspo2) or anti-Rspo2 to investigate the role of Rspo2 in IDD. RESULTS: Accumulation of CD206 in human and mouse IDD tissues was detected. Rheb deletion in the myeloid lineage (RheBcKO) increased the number of CD206+ M2-like macrophages (mean difference 18.6% [15.7-21.6%], P < 0.001), decreased cell apoptosis (mean difference -15.6% [-8.9 to 22.2%], P = 0.001) and attenuated the IDD process in the mouse IDD model. NPCs treated with Rspo2 displayed increased extracellular matrix catabolism and apoptosis; co-culture with a conditioned medium derived from RheBcKO mice inhibited these changes. Anti-Rspo2 treatment in the mouse caudal IVD puncture model exerted protective effects against IDD. CONCLUSIONS: Promoting CD206+ M2-like macrophages could reduce Rspo2 secretion, thereby alleviating experimental IDD. Rheb deletion may help M2-polarized macrophages accumulate and attenuate experimental IDD partially by inhibiting Rspo2 production. Hence, M2-polarized macrophages and Rspo2 may serve as therapeutic targets for IDD.
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Degeneração do Disco Intervertebral , Disco Intervertebral , Núcleo Pulposo , Humanos , Camundongos , Animais , Degeneração do Disco Intervertebral/patologia , Disco Intervertebral/metabolismo , Núcleo Pulposo/metabolismo , Apoptose , Modelos Animais de Doenças , Macrófagos/metabolismoRESUMO
OBJECTIVE: Joint involvement in SLE is the most frequent manifestation and shows a wide heterogeneity. It has not a valid classification and it is often underestimated. Subclinical inflammatory musculoskeletal involvement is not well known. We aim to describe the prevalence of joint and tendon involvement in hand and wrist of SLE patients, either with clinical arthritis, arthralgia or asymptomatic and compare it with healthy subjects using contrasted MRI. METHODS: SLE patients fulfilling SLICC criteria were recruited and classified as follows: group (G) 1: hand/wrist arthritis, G2: hand/wrist arthralgia, G3: no hand/wrist symptoms. Jaccoud arthropathy, CCPa and RF positivity, hand OA or surgery were excluded. Healthy subjects (HS) were recruited as controls: G4. Contrasted MRI of non-dominant hand/wrist was performed. Images were evaluated following RAMRIS criteria extended to PIP, Tenosynovitis score for RA and peritendonitis from PsAMRIS. Groups were statistically compared. RESULTS: A total of 107 subjects were recruited (G1: 31, G2:31, G3:21, G4:24). Any lesion: SLE patients 74.7%, HS 41.67%; P 0.002. Synovitis: G1: 64.52%, G2: 51.61%, G3: 45%, G4: 20.83%; P 0.013. Erosions: G1: 29.03%; G2: 54.84%, G3: 47.62%; G4: 25%; P 0.066. Bone marrow oedema: G1: 29.03%, G2: 22.58%, G3: 19.05%, G4: 0.0%; P 0.046. Tenosynovitis: G1: 38.71%; G2: 25.81%, G3: 14.29%, G4: 0.0%; P 0.005. Peritendonitis: G1: 12.90%; G2: 3.23%, G3: 0.0%, G4: 0.0%; P 0.07. CONCLUSION: SLE patients have a high prevalence of inflammatory musculoskeletal alterations confirmed by contrasted MRI, even if asymptomatic. Not only tenosynovitis but peritendonitis is also present.
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Artrite , Lúpus Eritematoso Sistêmico , Sinovite , Tenossinovite , Humanos , Tenossinovite/diagnóstico por imagem , Tenossinovite/etiologia , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/diagnóstico por imagem , Lúpus Eritematoso Sistêmico/patologia , Artralgia , Imageamento por Ressonância MagnéticaRESUMO
OBJECTIVE: To characterise the frequency and influence of tenosynovitis and tendon damage on pain and hand function using clinical examination and ultrasound (US) in hand osteoarthritis (HOA). METHODS: We included 86 patients with HOA and 23 age- and sex-matched control subjects. Extensor and flexor tendons of both hands were assessed by clinical examination and US for tenosynovitis, tendon damage. Conventional radiographs were acquired. Hand function was evaluated by the function subtest of the M-SACRAH questionnaire and the Moberg pick-up test. K-means cluster analyses was calculated to assess clusters based on radiographic features and sonographic tendon scores. RESULTS: Ultrasound identified the involvement of ≥ 1 tendon in 60/86 (69.8%) HOA patients compared with 2/23 (8.7%) subjects (p< 0.01) in the control group. In the HOA group, US detected tendon damage more often in flexor tendons compared with extensor tendons (2.1% 0.9%, p= 0.03), while tenosynovitis was observed more often in extensor tendons compared with flexor tendons (8% vs 0.6%, p< 0001). The sensitivity and specificity of clinical examination to detect tendon involvement was 81.4% and 34.6%, respectively on the patient level and 14.5% and 83.8% on the tendon level. The cluster analyses revealed one cluster with more radiographic features of HOA and more tendon damage while more tenosynovitis was found in cluster 2. M-SACRAH function did not correlate with tendon involvement on US. CONCLUSION: This study revealed a high frequency of tendon involvement in HOA. Tendon involvement on US did not impact hand function or self-reported pain.
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OBJECTIVES: Musculoskeletal ultrasound (MSUS) is increasingly used by rheumatologists in daily clinical practice. However, MSUS is only valuable in trained hands, and assessment of trainee competences is therefore essential before independent practice. Thus, this study aimed to establish validity evidence for the EULAR and the Objective Structured Assessment of Ultrasound Skills (OSAUS) tools used for assessing MSUS competences. METHODS: Thirty physicians with different levels of MSUS experience (novices, intermediates, and experienced) performed four MSUS examinations of different joint areas on the same rheumatoid arthritis patient. All examinations were video recorded (n = 120), anonymized, and subsequently assessed in random order by two blinded raters using first the OSAUS assessment tool followed by the EULAR tool 1 month after. RESULTS: The inter-rater reliability between the two raters was high for both the OSAUS and EULAR tools, with a Pearson correlation coefficient (PCC) of 0.807 and 0.848, respectively. Both tools demonstrated excellent inter-case reliability, with a Cronbach's alpha of 0.970 for OSAUS and 0.964 for EULAR. Furthermore, there was a strong linear correlation between the OSAUS and the EULAR performance scores and the participants' experience levels (R2 = 0.897 and R2 = 0.868, respectively) and a significant discrimination between different MSUS experience levels (P < 0.001 for both). CONCLUSIONS: MSUS operator competences can be assessed reliably and valid using either the OSAUS or the EULAR assessment tool, thereby allowing a uniform competency-based MSUS education in the future. Although both tools demonstrated high inter-rater reliability, the EULAR tool was superior to OSAUS. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT05256355.
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Artrite Reumatoide , Humanos , Reprodutibilidade dos Testes , Correlação de Dados , Mãos , Exame FísicoRESUMO
OBJECTIVES: Recurrent monoarthritis (RM) is a major challenge of many rheumatic diseases. Ablation is a well-known technique in the treatment of benign or malign lesions of different etiologies. We aimed to to investigate the success and safety of microwave ablation (MWA) as an adjunctive therapy in a cohort of medical treatment-resistant RM. METHODS: Patients with RM associated with different inflammatory diseases were included. MWA was performed after measuring the size of synovial hypertrophy with 15 or 20-watt power and different durations until microbubbles were shown indicating necrosis. Both clinical and radiologic data were recorded. RESULTS: We applied MWA in total of 24 knee joints of 10 female and 12 male patients aged between 22-71 years. Median intra-articular aspiration (IAA) need in the last 6 months before MWA was 5 (0-15). The median follow-up was 10 (3-16) months. Overall IAA count in the last 6 months before MWA in total of 144 months was 129 and decreased to 7 in post-MWA in total of 226 months (0.89 vs 0.03 per month, p< 0.001). The second MWA session was needed for 3 patients and a third session for 1. Functional disability and pain scores were improved significantly (median score from 9 to 1, p< 0.00001, in both). In magnetic resonance imaging, follow-up significant regression in synovial hypertrophy size was shown especially after 6th month. No complication was observed during the procedure or follow-up. CONCLUSION: As a less invasive technique compared with the surgical approach, MWA of synovial hypertrophy showed significant clinical improvement in RM safely. MWA seems promising as a treatment option candidate in the management of RM.
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OBJECTIVES: Interventional musculoskeletal ultrasound (MSUS) procedures are routinely performed in rheumatology practice. However, the efficacy and safety of the procedures rely on the competence of the physician, and assessment of skills is crucial. Thus, this study aimed to develop and establish validity evidence for a tool assessing trainees' interventional MSUS skills. METHODS: An expert panel of rheumatologists modified an existing tool for assessing competences in invasive abdominal and thoracic ultrasound procedures. The new tool (the Assessment of Interventional Musculoskeletal Ultrasound Skills (AIMUS) tool) reflects the essential steps in interventional MSUS. To establish validity evidence, physicians with different levels of interventional MSUS experience were enrolled and performed two procedures on a rubber fantom, simulating real patient cases. All performances were video recorded, anonymized, and assessed in random order by two blinded raters using the AIMUS tool. RESULTS: Sixty-five physicians from 21 different countries were included and categorized into groups based on their experience, resulting in 130 videos for analysis. The internal consistency of the tool was excellent, with a Cronbach's alpha of 0.96. The inter-case reliability was good with a Pearson's correlation coefficient (PCC) of 0.74 and the inter-rater reliability was moderate to good (PCC 0.58). The ability to discriminate between different levels of experience was highly significant (p< 0.001). CONCLUSIONS: We have developed and established validity evidence for a new interventional MSUS assessment tool. The tool can be applied in future competency-based educational programs, provide structured feedback to trainees in daily clinical practice, and ensure end-of-training competence.
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BACKGROUND: Surgical resection is the primary treatment for bone and soft tissue tumors. Negative margin status is a key factor in prognosis. Given the three-dimensional (3D) anatomic complexity of musculoskeletal tumor specimens, communication of margin results between surgeons and pathologists is challenging. We sought to perform ex vivo 3D scanning of musculoskeletal oncology specimens to enhance communication between surgeons and pathologists. METHODS: Immediately after surgical resection, 3D scanning of the fresh specimen is performed prior to frozen section analysis. During pathologic grossing, whether frozen or permanent, margin sampling sites are annotated on the virtual 3D model using computer-aided design (CAD) software. RESULTS: 3D scanning was performed in seven cases (six soft tissue, one bone), with specimen mapping on six cases. Intraoperative 3D scanning and mapping was performed in one case in which the location of margin sampling was shown virtually in real-time to the operating surgeon to help achieve a negative margin. In six cases, the 3D model was used to communicate final permanent section analysis. Soft tissue, cartilage, and bone (including lytic lesions within bone) showed acceptable resolution. CONCLUSIONS: Virtual 3D scanning and specimen mapping is feasible and may allow for enhanced documentation and communication. This protocol provides useful information for anatomically complex musculoskeletal tumor specimens. Future studies will evaluate the effect of the protocol on positive margin rates, likelihood that a re-resection contains additional malignancy, and exploration of targeted adjuvant radiation protocols using a patient-specific 3D specimen map.
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Neoplasias de Tecidos Moles , Cirurgia Assistida por Computador , Humanos , Estudos de Viabilidade , Prognóstico , Margens de Excisão , Cirurgia Assistida por Computador/métodos , Estudos RetrospectivosRESUMO
Frogs have a highly conserved body plan, yet they employ a diverse array of locomotor modes, making them ideal organisms for investigating the relationships between morphology and locomotor function, in particular whether anatomical complexity is a prerequisite for functional complexity. We use diffusible iodine contrast-enhanced microCT (diceCT) imaging to digitally dissect the gross muscle anatomy of the pelvis and hindlimbs for 30 species of frogs representing five primary locomotor modes, including the first known detailed dissection for some of the world's smallest frogs, forming the largest digital comparative analysis of musculoskeletal structure in any vertebrate clade to date. By linking musculoskeletal dissections and phylogenetic comparative methods, we then quantify and compare relationships between anatomy and function across over 160 million years of anuran evolution. In summary, we have found that bone lengths and pelvic crest sizes are generally not reliable predictors of muscle sizes, which highlights important implications for future palaeontological studies. Our investigation also presents previously unreported differences in muscle anatomy between frogs specialising in different locomotor modes, including several of the smallest frog hindlimb muscles, which are extremely difficult to extract and measure using traditional approaches. Furthermore, we find evidence of many-to-one and one-to-many mapping of form to function across the phylogeny. Additionally, we perform the first quantitative analysis of how the degree of muscle separation can differ between frogs. We find evidence that phylogenetic history is the key contributing factor to muscle separation in the pelvis and thigh, while the separation of shank muscles is influenced more strongly by locomotor mode. Finally, our anatomical 3D reconstructions are published alongside this manuscript to contribute towards future research and serve as educational materials.
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Heavy animals incur large forces on their limb bones, due to the transmission of body weight and ground reaction forces, and the contractions of the various muscles of the limbs. This is particularly true for rhinoceroses, the heaviest extant animals capable of galloping. Several studies have examined their musculoskeletal system and the forces their bones incur, but no detailed quantification has ever been attempted. Such quantification could help understand better the link between form and function in giant land animals. Here we constructed three-dimensional musculoskeletal models of the forelimb and hindlimb of Ceratotherium simum, the heaviest extant rhino species, and used static optimisation (inverse) simulations to estimate the forces applied on the bones when standing at rest, including magnitudes and directions. Overall, unsurprisingly, the most active muscles were antigravity muscles, which generate moments opposing body weight (thereby incurring the ground reaction force), and thus keep the joints extended, avoiding joint collapse via flexion. Some muscles have an antigravity action around several joints, and thus were found to be highly active, likely specialised in body weight support (ulnaris lateralis; digital flexors). The humerus was subjected to the greatest amount of forces in terms of total magnitude; forces on the humerus furthermore came from a great variety of directions. The radius was mainly subject to high-magnitude compressive joint reaction forces, but to little muscular tension, whereas the opposite pattern was observed for the ulna. The femur had a pattern similar to that of the humerus, and the tibia's pattern was intermediate, being subject to great compression in its caudal side but to great tension in its cranial side (i.e. bending). The fibula was subject to by far the lowest force magnitude. Overall, the forces estimated were consistent with the documented morphofunctional adaptations of C. simum's long bones, which have larger insertion areas for several muscles and a greater robusticity overall than those of lighter rhinos, likely reflecting the intense forces we estimated here. Our estimates of muscle and bone (joint) loading regimes for this giant tetrapod improve the understanding of the links between form and function in supportive tissues and could be extended to other aspects of bone morphology, such as microanatomy.
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Músculo Esquelético , Perissodáctilos , Animais , Perissodáctilos/fisiologia , Perissodáctilos/anatomia & histologia , Fenômenos Biomecânicos/fisiologia , Músculo Esquelético/fisiologia , Músculo Esquelético/anatomia & histologia , Membro Anterior/fisiologia , Membro Anterior/anatomia & histologia , Membro Posterior/fisiologia , Membro Posterior/anatomia & histologia , Simulação por ComputadorRESUMO
The accurate segmentation of individual muscles is essential for quantitative MRI analysis of thigh images. Deep learning methods have achieved state-of-the-art results in segmentation, but they require large numbers of labeled data to perform well. However, labeling individual thigh muscles slice by slice for numerous volumes is a laborious and time-consuming task, which limits the availability of annotated datasets. To address this challenge, self-supervised learning (SSL) emerges as a promising technique to enhance model performance by pretraining the model on unlabeled data. A recent approach, called positional contrastive learning, exploits the information given by the axial position of the slices to learn features transferable on the segmentation task. The aim of this work was to propose positional contrastive SSL for the segmentation of individual thigh muscles from MRI acquisitions in a population of elderly healthy subjects and to evaluate it on different levels of limited annotated data. An unlabeled dataset of 72 T1w MRI thigh acquisitions was available for SSL pretraining, while a labeled dataset of 52 volumes was employed for the final segmentation task, split into training and test sets. The effectiveness of SSL pretraining to fine-tune a U-Net architecture for thigh muscle segmentation was compared with that of a randomly initialized model (RND), considering an increasing number of annotated volumes (S = 1, 2, 5, 10, 20, 30, 40). Our results demonstrated that SSL yields substantial improvements in Dice similarity coefficient (DSC) when using a very limited number of labeled volumes (e.g., for S $$ S $$ = 1, DSC 0.631 versus 0.530 for SSL and RND, respectively). Moreover, enhancements are achievable even when utilizing the full number of labeled subjects, with DSC = 0.927 for SSL and 0.924 for RND. In conclusion, positional contrastive SSL was effective in obtaining more accurate thigh muscle segmentation, even with a very low number of labeled data, with a potential impact of speeding up the annotation process in clinics.
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INTRODUCTION: Computed tomography (CT) is routinely employed on the evaluation of dyspnea, yet limited data exist on its assessment of diaphragmatic muscle. This study aimed to determine the capability of CT in identifying structural changes in the diaphragm among patients with ultrasound-confirmed diaphragmatic dysfunction. METHODS: Diaphragmatic ultrasounds conducted between 2018 and 2021 at our center in Marseille, France, were retrospectively collected. Diaphragmatic pillars were measured on CT scans at the L1 level and the celiac artery. Additionally, the difference in height between the two diaphragmatic domes in both diaphragmatic dysfunction cases and controls was measured and compared. RESULTS: A total of 65 patients were included, comprising 24 with diaphragmatic paralysis, 13 with diaphragmatic weakness, and 28 controls. In the case group (paralysis and weakness) with left dysfunctions (n = 24), the CT thickness of the pillars at the level of L1 and the celiac artery was significantly thinner compared with controls (2.0 mm vs. 7.4 mm and 1.8 mm vs. 3.1 mm, p < 0.001 respectively). Significantly different values were observed for paralysis (but not weakness) in the right dysfunction subgroup (n = 15) (2.6 mm vs. 7.4 mm and 2.2 mm vs. 3.8 mm, p < 0.001 respectively, for paralysis vs. controls). Regardless of the side of dysfunction, a significant difference in diaphragmatic height was observed between cases and controls (7.70 cm vs. 1.16 cm and 5.51 cm vs. 1.16 cm, p < 0.001 for right and left dysfunctions, respectively). Threshold values determined through ROC curve analyses for height differences between the two diaphragmatic domes, indicative of paralysis or weakness in the right dysfunctions, were 4.44 cm and 3.51 cm, respectively. Similarly for left dysfunctions, the thresholds were 2.70 cm and 2.48 cm, respectively, demonstrating good performance (aera under the curve of 1.00, 1.00, 0.98, and 0.79, respectively). CONCLUSION: In cases of left diaphragmatic dysfunction, as well as in paralysis associated with right diaphragmatic dysfunction, CT revealed thinner pillars. Additionally, a notable increase in the difference in diaphragmatic height demonstrated a strong potential to identify diaphragmatic dysfunction, with specific threshold values.
Assuntos
Diafragma , Debilidade Muscular , Humanos , Diafragma/diagnóstico por imagem , Estudos Retrospectivos , Ultrassonografia/métodos , Paralisia , Tomografia Computadorizada por Raios X , TomografiaRESUMO
Fibromyalgia (FMS) is a persistent syndrome marked by widespread musculoskeletal pain and behavioural symptoms. Given the hypothesis linking FMS aetiology to mitochondrial dysfunction and oxidative stress, we examined the biochemical correlation among these factors by studying specific proteins associated with mitochondrial homeostasis in muscle. Additionally, this study investigated the role of Boswellia serrata gum resin extract (BS), known for its various functions, including the potent induction of antioxidant enzymes, in determining protective or reparative mechanisms in the muscle cells. Sprague-Dawley rats were injected with reserpine to induce FMS. These animals exhibited moderate changes in hind limb skeletal muscles, experiencing mobility difficulties. Additionally, there were noteworthy morphological and ultrastructural alterations, along with the expression of myogenin, mitochondrial enzymes and oxidative stress markers in the gastrocnemius muscle. Interestingly, BS demonstrated a reduction in spontaneous motor activity difficulties. Moreover, BS showed a positive impact on musculoskeletal morphostructural aspects, as well as a decrease in oxidative stress and mitochondrial alterations. In particular, BS restored the mRNA expression of citrate synthase and cytochrome-c oxidase subunit II and the activity of electron transfer chain complexes. BS also influenced mitochondrial biogenesis, upregulating PGC-1α expression and the related transcription factors (Nrf1, Tfam, Nrf2, FOXO3a, SIRT3, GCLC, NQO1, SOD2 and GPx4), oxidative stress (lipid peroxidation, GSH levels and GSH-Px activity) and mitochondrial dynamics and function (Mnf2 expression and CoQ10 levels). Overall, this study underlined the key role of the mitochondrial alteration in FMS and that BS had a very high antioxidant effect in these organelles and also in the cells.