Size and Proportions of Slow-Twitch and Fast-Twitch Muscle Fibers in Human Costal Diaphragm

Chen

et al. 2020

Sci Rep

Masticatory muscle thickness provides objective measurements of the oral motor function, which may change in patients with oral myofascial pain. In this study, we aimed to establish a reliable ultrasound (US) protocol for imaging the superficial and deep masticatory muscles and to identify the potential influencers of the measurements. Forty-eight healthy participants without orofacial pain were enrolled. The intra-and inter-rater reliabilities of US measurements for masseter, temporalis, and lateral pterygoid muscles were assessed. Intraclass correlation coefficients for all muscles were greater than 0.6. The generalised estimating equation was used to analyse the impact of age, gender, laterality, and body mass index on the measurements, whereby age and body mass index were likely to be associated with an increase in masticatory muscle thickness. The thickness tended to be lesser in females. Laterality seemed to exert minimal influence on masticatory muscle thickness. Our study shows acceptable reliability of US in the evaluation of superficial and deep masticatory muscle thickness. Future studies are warranted to validate the usefulness of US imaging in patients with oral myofascial pain syndrome. Temporomandibular disorder (TMD) is frequently observed in patients seeking dental treatment. It comprises various findings concerning the stomatognathic system, involving the temporomandibular joints, masticatory muscles, teeth, and ears 1,2. The prevalence of TMDs in the general population ranges from 34.9 to 42.4% across different studies 3,4 , and the incidence is more prevalent in females 5. Of note, oral myofascial pain is commonplace in about 10-15% of patients with TMD 6. The aetiology of oral myofascial pain is still controversial. The proposed mechanisms include overuse of the masticatory muscles and a decrease in its pain threshold following central sensitization 7. While overuse might lead to hypertrophy of the masticatory muscles in the early stages, persistent pain could result in disuse atrophy in chronic cases 8. In this sense, masticatory muscle thickness provides objective measurements of the oral motor function 9 , which is supposed to change in patients suffering from oral myofascial pain. Several imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) have been used to image the masticatory muscles. CT allows precise delineation of the skull bone where the masticatory muscles attach. However, radiation and poor resolution of the soft tissues make it unsuitable for muscle thickness measurements. Nowadays, MRI serves as the gold standard for depicting soft tissue pathologies 10 , but it is limited by its high cost and contraindications in patients with metal implants. US has various advantages over CT and MRI, i.e. real-time evaluation, zero radiation, cost-effectiveness, portability, and ease of dynamic examination 11. Further, it is capable of delineating muscle fibres-making it highly effective for imaging muscle trauma and neuromuscular diseas...

Section: Intra-rater Icc (95% Ci)mentioning

confidence: 95%

Ultrasound measurements of superficial and deep masticatory muscles in various postures: reliability and influencers

Chen

et al. 2020

Sci Rep

Molecular Nutrition Food Res

“…Muscle fiber cross‐sectional area (CSA) and the numerical proportions of slow‐MyHC were calculated using an ImageJ 1.43 analyzing system, respectively. On average, 150 muscle fibers were analyzed in each sample of red gastrocnemius as described in previous studies …”

Section: Methodsmentioning

confidence: 99%

“…On average, 150 muscle fibers were analyzed in each sample of red gastrocnemius as described in previous studies. [34,35]…”

Section: Immunohistochemistry For Fiber Type and Cross-sectional Areamentioning

confidence: 99%

6‐Gingerol Improves Ectopic Lipid Accumulation, Mitochondrial Dysfunction, and Insulin Resistance in Skeletal Muscle of Ageing Rats: Dual Stimulation of the AMPK/PGC‐1α Signaling Pathway via Plasma Adiponectin and Muscular AdipoR1

Liu

Yao

Wang

et al. 2019

Scope This study investigates the dual actions of 6‐gingerol in stimulating both plasma adiponectin and muscular adiponectin receptor signaling in naturally ageing rats. Methods and results Twenty‐two‐month‐old male SD rats were treated with 6‐gingerol (0.2 mg kg–1, once daily) for 7 weeks. 6‐Gingerol can attenuate age‐associated high plasma triglyceride, glucose, and insulin concentrations under fasting conditions as well as suppress the increase in the HOMA‐IR index and inhibit the decrease of muscular p‐Akt/Akt protein in ageing rats, which indicates an improvement of systemic and muscular insulin sensitivity. Accompanying these changes, treatment with 6‐gingerol attenuates excessive triglyceride accumulation, enhances mitochondrial function, and promotes a transition from a fast‐ to slow‐fiber type and muscle oxidative metabolism in the red gastrocnemius of ageing rats. More importantly, 6‐gingerol not only increases the plasma and adipose tissue adiponectin concentrations, but also elevates muscular AdipoR1 expression and activates downstream AMPK phosphorylation as well as upregulates PGC‐1α in vivo and in vitro. Conclusion 6‐Gingerol may improve ectopic lipid accumulation, mitochondrial dysfunction, and insulin resistance in skeletal muscle of ageing rats. These effects rely, at least in part, on the elevated plasma adiponectin concentration and muscle AdipoR1 level to dually activate the AMPK/PGC‐1α signaling pathway.

“…Another possible hypothesis is the diaphragm muscle fibre phenotype of approximately 76% slow-twitch oxidative and fast oxidative fibres, suggesting greater muscle reserve [46]. Moreover, the smaller diameter and cross-sectional area of the diaphragm compared with other muscles [47], reduces the exchange distance with the capillary and promotes a more efficient oxygen supply; these factors could be responsible for the increased diaphragm resistance to fatigue. According to the literature reports, the most reasonable independent variables for explaining TLC and FVC were right diaphragmatic thickness in maximal expiration and right diaphragmatic movement during deep breathing.…”

Section: Discussionmentioning

confidence: 99%

Diaphragm ultrasonography in adults with sickle cell anemia: evaluation of morphological and functional aspects

et al. 2020

Objectives: To assess morphological and functional aspects of the diaphragm by ultrasonography (US) in adults with sickle cell anemia (SCA) and evaluate if the diaphragmatic musculature can play a role in changes found in pulmonary function tests (PFTs) of these patients. Methods: This is a cross-sectional observational and single-center study involving 40 adults with SCA who underwent diaphragm US and PFTs with a maximum of 1 month between the two tests. Diaphragm US was performed in B and M modes, and echogenicity, thickness and movement of the muscle was assessed in different respiratory maneuvers. Results: Diaphragms had preserved echogenicity and the thickness was not significantly different between the groups. The SCA group exhibited significantly higher movement of the right hemidiaphragm during deep breathing (p = 0.004) and the sniff test (p = 0.0008) and lower movement of the left hemidiaphragm during quiet breathing (p = 0.009). There was a predominance of restrictive pattern (65%) and a global reduction in respiratory muscle strength (RMS) (70%). Conclusions: This study shows that adults with SCA had normal morphostructural aspects and absence of diaphragm dysfunction. Otherwise, they presented greater movement of the right hemidiaphragm during deep breathing and sniff test maneuvers. Despite the restrictive pattern and the reduction in RMS found in PFTs, the diaphragm of young adults with SCA did not have weakness or paralysis.