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9,798 results for “muscles”
Silhouette CNS Muscle
Drawing uploaded to scidraw.io on: 15 November 2019
Ultrasound-derived changes in thickness of human ankle plantar flexor muscles during walking and running are not homogeneous along the muscle mid-belly region
<p>Skeletal muscle thickness is a valuable indicator of several aspects of a muscle's functional capabilities. We used computational analysis of ultrasound images, recorded from 10 humans walking and running at a range of speeds (0.7 – 5.0 m s<sup>-1</sup>), to quantify interactions in thickness change between three ankle plantar flexor muscles (soleus, medial and lateral gastrocnemius) and quantify thickness changes at multiple muscle sites within each image. Statistical analysis of thickness change as a function of stride cycle (1d statistical parametric mapping) revealed significant differences between soleus and both gastrocnemii across the whole stride cycle as they bulged within the shared anatomical space. Within each muscle, changes in thickness differed between measurement sites but not locomotor condition. For some of the stride, thickness measures taken from the distal-mid image region represented the mean muscle thickness, which may therefore be a reliable region for these measures. Assumptions that muscle thickness is constant during a task, often made in musculoskeletal models, do not hold for the muscles and locomotor conditions studied here and researchers should not assume that a single thickness measure, from one point of the stride cycle or a static image, represents muscle thickness during dynamic movements.</p>
Figure 8 from: Sugiharto SP, Bintoro N, Karyadi JNW, Pranoto Y (2020) Supercritical carbon dioxide pasteurization to reduce the activity of muscle protease and its impact on physicochemical properties of Nile tilapia. Research Ideas and Outcomes 6: e56887. https://doi.org/10.3897/rio.6.e56887
Figure 8 Effect of HPCD (40 °C and 15 min) of hardness of fillet. Bars with the same letter were not significantly different. Vertical lines indicate standard deviation.
Figure 2 from: Sugiharto SP, Bintoro N, Karyadi JNW, Pranoto Y (2020) Supercritical carbon dioxide pasteurization to reduce the activity of muscle protease and its impact on physicochemical properties of Nile tilapia. Research Ideas and Outcomes 6: e56887. https://doi.org/10.3897/rio.6.e56887
Figure 2 The appearance of whole fish Nile tilapia after subjected to CO2 pasteurization at 40 oC and for 15 min with the following pressures: A. No treatment, B. 70 bar, C. 75 bar, D. 80 bar, E. 85 bar, and F. 90 bar
Host plant defense produces species-specific alterations to flight muscle protein structure and flight-related fitness traits of two armyworms
<p>Insects manifest phenotypic plasticity in their development and behavior in response to plant defenses, via molecular mechanisms that produce tissue-specific changes. Phenotypic changes might vary between species that differ in their preferred hosts and these effects could extend beyond larval stages. To test this, we manipulated the diet of southern armyworm (SAW; Spodoptera eridania) and fall armyworm (FAW; Spodoptera frugiperda) using a tomatomutant for jasmonic acid plant defense pathway (def1), and wild-type plants, and then quantified gene expression of Troponin t (Tnt) and flight muscle metabolism of the<br> adult insects. Differences in Tnt spliceform ratios in insect flight muscles correlate with changes to flight muscle metabolism and flight<br> muscle output. We found that SAW adults reared on induced def1 plants had a higher relative abundance (RA) of the A isoform of Troponin t (Tnt A) in their flight muscles; in contrast, FAW adults reared on induced def1 plants had a lower RA of Tnt A in their flight muscles compared with adults reared on def1 and controls. Although massadjusted flightmetabolic rate showed no independent host plant effects in either species, higher flight metabolic rates in SAW correlated with increased RA of Tnt A. Flight muscle metabolism also showed an interaction of host plants with Tnt A in both species, suggesting that host plants might be influencing flight muscle metabolic output by altering Tnt. This study illustrates how insects respond to variation in host plant chemical defense by phenotypic modifications to their flight muscle proteins, with possible implications for dispersal.</p>
Figure 2 in The muscles, body wall and valve-opening mechanism of extant craniid (inarticulated) brachiopods
Figure 2. Digital and scanning electron micrographs (SEM) illustrating anatomical features. (A–H) Novocrania californica. (A). SEM of a piece of anterior adductor muscle, showing fibres make up whole length. (B) SEM close-up of fibres in A. (C) Lophophore cut to show brachial muscle and empty hydrostatic skeleton channel. (D) Ventral view of anterior adductor muscle,
Figure 5 in The muscles, body wall and valve-opening mechanism of extant craniid (inarticulated) brachiopods
Figure 5. Line drawings and digital and scanning electron micrographs illustrating organic ventral mounds and lophophore filaments. (A, B) Novocrania lecointei. (A) NIWA 37947. Transparent organic ventral valve with organic ventral mound on dark rock. (B) Cutaway drawing down midline. (C–F) Novocrania anomala. (C) OU 44526a. Ventral valve with organic ventral mound. (D) OU 44525a. Ventral valve with organic mound rotted away. (E) OU 39355. Dorsal valve with muscle scars flush with valve surface. (F) Reproduction of illustration of N. anomala with lophophore filaments extended (from Barrett 1856). All scale bars 2 mm. Abbreviations: aasc, anterior adductor muscle scar; bwi, "batwing" shaped outline of organic ventral valve; dv, dorsal valve; fi, filaments; obisc, oblique internal muscle scar; opab, organic posterior adductor base; ovm, organic ventral mound; ovv, organic ventral valve; pasc, posterior adductor muscle scar; vv, ventral valve.
Fatigue resistant jaw muscles facilitate long-lasting courtship behavior in the southern alligator lizard (Elgaria multicarinata)
<p>The southern alligator lizard (<i>Elgaria multicarinata</i>) exhibits a courtship behavior during which the male firmly grips the female's head in his jaws for many hours at a time. This extreme behavior counters the conventional wisdom that reptile muscles are fast to fatigue and incapable of powering high endurance behaviors. We conducted <i>in situ</i> experiments in which the jaw-adductor muscles of lizards were stimulated directly while bite force was measured simultaneously with a force transducer. Fatigue tests were performed by supramaximally and bilaterally stimulating the muscles for several minutes with a series of tetanic trains. Our results show that a substantial sustained force gradually develops during the first few minutes of the fatigue test. This sustained force persists after peak tetanic forces have declined to a fraction of their initial magnitude. The observed sustained force during <i>in situ</i> fatigue tests is consistent with the natural courtship behavior of these lizards and likely reflects physiological specialization. The results of molecular analysis reveal that the jaw-adductor muscles contain masticatory myosin and tonic myosin fibers. We propose that the presence of tonic fibers may explain the unusual sustained force properties during mate-holding behavior. The characterization of muscle properties that facilitate extreme performance in specialized systems may help reveal general mechanisms, especially when done in light of convergently evolved systems exhibiting similar performance characteristics.</p>
Full summary statistics of mixQTL for GTEx v8 Muscle_Skeletal
The mixQTL method is described in paper doi.org/10.1101/2020.04.22.050666. Please cite the original paper if using the data.
Data from: Preserved single muscle fiber specific force in facioscapulohumeral muscular dystrophy
Objective: To investigate single muscle fiber contractile performance in muscle biopsies from patients with facioscapulohumeral muscular dystrophy, one of the most common hereditary muscle disorders. Methods: we collected 26 vastus lateralis and 24 tibialis anterior muscle biopsies from 14 genetically confirmed FSHD patients and 12 healthy controls. Single muscle fibers (N = 547) were isolated for contractile measurements. Titin content and PEVK phosphorylation were examined in vastus lateralis muscle biopsies. Results: Single muscle fiber specific force is intact at saturating and physiological calcium concentrations in all FSHD biopsies, with (FSHDFAT) and without (FSHDNORMAL) fatty infiltration. Myofilament calcium sensitivity of force is increased in single muscle fibers obtained from FSHD muscle biopsies with increased fatty infiltration, but not in FSHD muscle biopsies without fatty infiltration (pCa50: 5.77-5.80 in healthy control, 5.74-5.83 in FSHDNORMAL and 5.86-5.90 in FSHDFAT single muscle fibers). Cross-bridge cycling kinetics at saturating calcium concentrations and myofilament cooperativity did not differ from healthy controls. Passive force was increased in all FSHD muscle fibers, resulting in increased fiber stiffness. Titin content was increased in FSHD biopsies, however titin phosphorylation did not differ from healthy controls. Conclusion: Muscle weakness in patients with FSHD is not caused by reduced specific force of individual muscle fibers, even in severely affected tissue. Muscle fiber calcium sensitivity of force was increased in severely affected tissue and probably is a compensatory mechanism to maintain specific force. Fiber stiffness was increased in FSHD muscle with and without fatty infiltration, suggesting an early event in disease pathology.
Appendicular muscle mass, thigh intermuscular fat infiltration and risk of fall in postmenopausal osteoporotic elder women
<p>This data set refers to the study registered at clinicaltrials.gov (ref. n.: NCT03382366). This observational, cross-sectional, pilot study was approved by the Ethical Committee of Vita-Salute San Raffaele University (ref. n.: 17/INT/2017) and all procedures were performed in compliance with current national and international laws and regulations governing the use of human subjects (Declaration of Helsinki). </p> <p>The association between the quantity and composition of skeletal muscle and the decline in physical function in elderly is poorly understood. Therefore, the primary aim of this cross-over study was to investigate the association between thigh intramuscular adipose tissue infiltration, appendicular muscle mass and risk of fall in postmenopausal osteoporotic elder women. Second, we aimed at examining the differences in muscle mass, IMAT and risk of fall in the same sample of older subjects after being classified as sarcopenic or non sarcopenic on the basis of the dual energy X-ray absorptiometry-based Appendicular Skeletal Muscle Mass Index.</p>
Transcriptomic data and analyses of shMeg3 muscle in vitro and in vivo
<p>Formation of skeletal muscle is among the most striking examples of cellular plasticity in animal tissue development, and while muscle progenitor cells are reprogrammed by epithelial-mesenchymal transition (EMT) to migrate during embryonic development, regulation of EMT in postnatal myogenesis remains poorly understood. Here, we demonstrate that the long noncoding RNA (lncRNA) <em>Meg3</em> regulates EMT in myoblast differentiation and skeletal muscle regeneration. Chronic inhibition of <em>Meg3</em> in C2C12 myoblasts induced EMT, and supressed cell state transitions required for differentiation. Furtheremore, adenoviral <em>Meg3</em> knockdown compromised muscle regeneration, which was accompanied by abnormal mesenchymal gene expression and interstitial cell proliferation. Transcriptomic and pathway analyses of <em>Meg3-</em>depleted C2C12 myoblasts and injured skeletal muscle revealed a significant dysregulation of EMT-related genes, and identified TGFβ as a key upstream regulator. Importantly, inhibition of TGFβR1 and its downstream effectors, and the EMT-related transcriptional repressor Snai2, restored many aspects of myogenic differentiation in <em>Meg3</em>-depleted myoblasts <em>in vitro</em>. We further demonstrate that reduction of <em>Meg3-</em>dependent Ezh2 activity results in epigenetic alterations associated with TGFβ activation. Thus, <em>Meg3</em> regulates myoblast identity to facilitate progression into muscle differentiation.</p>
Data from: The effect of interaural timing on the posterior auricular muscle reflex in normal adult volunteers
The posterior auricular muscle (PAM) reflex to sounds has been used clinically to determine hearing threshold as an alternative to other audiological diagnostic measures such as the auditory brainstem response. We have shown that the PAM response is also sensitive to interaural timing differences in normally hearing adults. PAM responses were evoked by both ipsilateral/ contralateral monaural stimulation and by binaural stimulation. Introducing sound delays ipsilaterally or contralaterally decreased the PAM response amplitude and increased its latency. The PAM response in this study shows a qualitatively similar pattern to that seen by the binaural interaction component (BIC) of the auditory brainstem potential to binaural clicks described in previous studies, in that both: have their shortest latency and maximal amplitudes centered around zero interaural timing differences, have response latencies increase with increasing interaural delays up to 1.2 ms and have response amplitudes decrease with increasing interaural delays of up to 1.2 ms. Our data show that the PAM response may be useful in measuring binaural integration in humans non-invasively for diagnostic or research studies.
Data from: Muscle tradeoffs in a power-amplified prey capture system
Should animals operating at great speeds and accelerations use fast or slow muscles? The answer hinges on a fundamental tradeoff: muscles can be maximally fast or forceful, but not both. Direct lever systems offer a straightforward manifestation of this tradeoff, yet the fastest organisms use power amplification, not direct lever action. Power-amplified systems typically use slow, forceful muscles to pre-load springs which then rapidly release elastic potential energy to generate high speeds and accelerations. However, a fast response to a stimulus may necessitate fast spring-loading. Across 22 mantis shrimp species (Stomatopoda), this study examined how muscle anatomy correlates with spring mechanics and appendage type. We found that muscle force is maximized through physiological cross-sectional area, but not through sarcomere length. Sit-and-wait predators had the shortest sarcomere lengths (fastest contractions) and the slowest strike speeds. The species that crush shells ("smashers") had the fastest speeds, most forceful springs and longest sarcomeres. The origin of the smasher clade yielded dazzlingly high accelerations, perhaps due to the release from fast spring-loading for evasive prey capture. This study offers a new window into the dynamics of force-speed tradeoffs in muscles in the biomechanical, comparative evolutionary framework of power-amplified systems.
Data from: Prognostic value of ki67 in BCG-treated non-muscle invasive bladder cancer: a meta-analysis and systematic review
Objectives: The aim of this study was to explore the prognostic value of ki67 as a marker in non-muscle-invasive bladder cancer (NMIBC) patients treated with Bacillus Calmette–Guérin (BCG). Methods: Studies were systematically retrieved from the relevant databases (Web of Science, PubMed, Cochrane Library, and Embase), and the expiry date was May 2017. The research steps referred to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. Results: A total of 11 studies that complied with the inclusion criteria were enrolled. The expression of ki67 was not statistically significantly associated with recurrence-free survival (RFS) [hazard ratio (HR): 1.331; 95% CI: 0.980–1.809)]. No significant heterogeneity was found among all included studies (I2 = 36.7%, P = 0.148). The expression of ki67 was statistically significantly associated with progression-free survival (PFS) (HR: 2.567; 95% CI: 1.562–4.219), and the overexpression of ki67 was the risk factor for PFS. Significant heterogeneity was noted among all the included studies (I2 = 55.6%, P = 0.021). The studies that might cause heterogeneity were excluded using the Galbraith plot, and then the meta-analysis was performed again. The results showed that the expression of ki67 was still associated with PFS (HR: 2.922; 95% CI: 2.002–4.266). Conclusions: The overexpression of ki67 was the risk factor for PFS, and the relationship between the expression of ki67 and RFS was not statistically significant in patients with NMIBC treated with BCG intravesical immunotherapy. Well-designed, prospective, randomized controlled trials with a large sample size are still needed to validate the findings.
Data from: Hindlimb muscle function in turtles: is novel skeletal design correlated with novel muscle function?
Variations in musculoskeletal lever systems have formed an important foundation for predictions about the diversity of muscle function and organismal performance. Changes in the structure of lever systems may be coupled with changes in muscle use and give rise to novel muscle functions. The two extant turtle lineages, cryptodires and pleurodires, exhibit differences in hindlimb structure. Cryptodires possess the ancestral musculoskeletal morphology, with most hip muscles originating on the pelvic girdle, which is not fused to the shell. In contrast, pleurodires exhibit a derived morphology, in which fusion of the pelvic girdle to the shell has resulted in shifts in the origin of most hip muscles onto the interior of the shell. To test how variation in muscle arrangement might influence muscle function during different locomotor behaviors, we combined measurements of muscle leverage in five major hindlimb muscles with data on muscle use and hindlimb kinematics during swimming and walking in representative semiaquatic cryptodires and pleurodires. We found substantial differences in muscle leverage between the two species. Additionally, we found that there were extensive differences in muscle use in both species, especially while walking, with some pleurodire muscles exhibiting novel functions associated with their derived musculoskeletal lever system. However, the two species shared similar overall kinematic profiles within each environment. Our results suggest that changes in limb lever systems may relate to changes in limb muscle motor patterns and kinematics, but that other factors must also contribute to differences in muscle activity and limb kinematics between these taxa.
Data from: Physiological tremor reveals how thixotropy adapts skeletal muscle for posture and movement
People and animals can move freely, but they must also be able to stay still. How do skeletal muscles economically produce both movement and posture? Humans are well known to have motor units with relatively homogeneous mechanical properties. Thixotropic muscle properties can provide a solution by providing a temporary stiffening of all skeletal muscles in postural conditions. This stiffening is alleviated almost instantly when muscles start to move. In this paper, we probe this behaviour. We monitor both the neural input to a muscle, measured here as extensor muscle electromyography (EMG), and its output, measured as tremor (finger acceleration). Both signals were analysed continuously as the subject made smooth transitions between posture and movement. The results showed that there were marked changes in tremor which systematically increased in size and decreased in frequency as the subject moved faster. By contrast, the EMG changed little and reflected muscle force requirement rather than movement speed. The altered tremor reflects naturally occurring thixotropic changes in muscle behaviour. Our results suggest that physiological tremor provides useful and hitherto unrecognized insights into skeletal muscle's role in posture and movement.
Data from: Lower extremity muscle pathology in myotonic dystrophy type 1 assessed by quantitative MRI
Objective: To determine the value of quantitative MRI to provide imaging biomarkers for disease in 20 different upper and lower leg muscles of myotonic dystrophy type 1 (DM1) patients. Methods: We acquired images covering these muscles in 33 genetically and clinically well-characterized DM1 patients and 10 unaffected controls. MR images were recorded with a Dixon method to determine muscle fat fraction, muscle volume and contractile muscle volume, and a multi-spin echo sequence to determine T2 water relaxation time (T2water), reflecting putative oedema. Results: Muscles in DM1 patients had higher fat fractions than muscles of controls (15.6%±11.1% vs. 3.7%±1.5%). Also, patients had smaller muscle volumes (902±232 cm3 vs. 1097±251 cm3), contractile muscle volumes (779±247 cm3 vs. 1054±246 cm3), and increased T2water (33.4±1.0 ms vs. 31.9±0.6 ms), indicating atrophy and oedema, respectively. Lower leg muscles were affected most frequently, especially the gastrocnemius medialis and soleus. Distribution of fat content per muscle indicated gradual fat infiltration in DM1. Between-patient variation in fat fraction was explained by age (~45%), and another ~14% by estimated progenitor CTG repeat length (r2 = 0.485) and somatic instability (r2 = 0.590). Fat fraction correlated with the six-minute walk test (r = -0.553) and muscular impairment rating scale (r = 0.537), and revealed subclinical muscle involvement. Conclusion: This cross-sectional quantitative MRI study of 20 different lower extremity muscles in DM1 patients revealed abnormal values for muscle fat fraction, volume and T2water, which therefore may serve as objective biomarkers to assess disease state of skeletal muscles in these patients.
Data from: A novel accessory respiratory muscle in the American alligator (Alligator mississippiensis)
The muscles that effect lung ventilation are key to understanding the evolutionary constraints on animal form and function. Here, through electromyography, we demonstrate a newly discovered respiratory function for the iliocostalis muscle in the American alligator (Alligator mississippiensis). The iliocostalis is active during expiration when breathing on land at 28C and this activity is mediated through the uncinate processes on the vertebral ribs. There was also an increase in muscle activity during the forced expirations of alarm distress vocalisations. Interestingly we did not find any respiratory activity in the iliocostalis when the alligators were breathing with their body submerged in water at 18C, which resulted in a reduced breathing frequency. The iliocostalis is an accessory breathing muscle that alligators are able to recruit in to assist expiration under certain conditions.
Data from: Frog tongue acts as muscle-powered adhesive tape
Frogs are well known to capture fast-moving prey by flicking their sticky tongues out of the mouth. This tongue projection behaviour happens extremely fast which makes frog tongues a biological high-speed adhesive system. The processes at the interface between tongue and prey, and thus the mechanism of adhesion, however, are completely unknown. Here, we captured the contact mechanics of frog tongues by filming tongue adhesion at 2000 frames per second through an illuminated glass. We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction. When the tongue detaches, mucus fibrils form between the tongue and the target. Fibrils commonly occur in pressure- sensitive adhesives, and thus frog tongues might be a biological analogue to these engineered materials. The fibrils in frog tongues are related to the presence of microscopic papillae on the surface. Together with a layer of nanoscale fibres underneath the tongue epithelium, these surface papillae will make the tongue adaptable to asperities. For the first time, to the best of our knowledge, we are able to integrate anatomy and function to explain the processes during adhesion in frog tongues.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.