Changes In Muscle Structure Research Articles

Acupuncture improves the structure of spastic muscle and decreases spasticity by enhancing GABA, KCC2, and GABAAγ2 in the brainstem in rats after ischemic stroke.

Increasing data show that structural changes of spastic muscle and hyperexcitability of reticulospinal tract (RST) are involved in the pathogenesis of spasticity after stroke (SAS). Our previous study has indicated that the anti-spastic effect of acupuncture, especially waggle needling (WN, a multiple directional needling method with joint movement), on SAS rats was related to the KCC2-GABAA pathway in cerebral cortex. Furthermore, as a peripheral stimulation to treat upper motor neuron injury-related spasticity, acupuncture's effect on peripheral spastic muscles and inhibitory neurotransmitters in the brainstem, the origin of the RST, should be further clarified. This study aimed to examine the effect of acupuncture on the structure of spastic muscle and on the KCC2-GABAA pathway in the brainstem of SAS rats. Middle cerebral artery occlusion (MCAO) or a sham operation were conducted in SD rats to establish SAS and control models. Behavioral assays, muscle myosin ATPase staining, and molecular biology technologies were used to compare different groups. In SAS models, hindlimb motor ability was decreased, neurologic deficits and spasticity were induced, the proportion of type I muscle fibers in spastic muscle was increased, and the expressions of γ-aminobutyric acid (GABA), KCC2, and the GABAAγ2 subunit of the pentameric GABAA receptor in the brainstem were decreased. Acupuncture including WN and perpendicular needling (PN) reversed these effects of MCAO. Furthermore, the therapeutic effect of WN was better than that of PN. Acupuncture after MCAO improves the structure of spastic muscle and decreases spasticity probably at least partly by enhancing GABA, KCC2, and GABAAγ2 in the brainstem in SAS rats.

MP21-20 EXPLORING ERECTILE HEMODYNAMICS IN MEN COMPLAINING OF HARD-FLACCID SYNDROME (HFS)

You have accessJournal of UrologyCME1 May 2022MP21-20 EXPLORING ERECTILE HEMODYNAMICS IN MEN COMPLAINING OF HARD-FLACCID SYNDROME (HFS) John Sullivan, Carolyn Salter, Jose Flores, Pat Guhring, Marilyn Parker, and John Mulhall John SullivanJohn Sullivan More articles by this author , Carolyn SalterCarolyn Salter More articles by this author , Jose FloresJose Flores More articles by this author , Pat GuhringPat Guhring More articles by this author , Marilyn ParkerMarilyn Parker More articles by this author , and John MulhallJohn Mulhall More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002554.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: There is increasing awareness of a condition, vernacularly termed HFS, in which men complain of subjective and palpable abnormalities in the flaccid penis (hardness, heaviness) often associated with erectile dysfunction (ED). We attempted to define erectile hemodynamic profiles in this population. METHODS: The study population consisted of (i) males ≥18 years of age (ii) who presented with self-diagnosed HFS (iii) who underwent comprehensive history and examination (including genital and lower extremity neurological) and (iv) penile duplex Doppler ultrasound (PDDU). PDDU was performed using redosing of vasodilators. PSV ≥35 cm/s and EDV ≤3 were considered normal. Patients with Peyronie’s disease or a history of intracavernosal injection therapy were excluded. RESULTS: 88 men were analyzed. Mean age was 28±12 years. Median number of vascular comorbidities was zero (0, 1). 66 (75%) had a history of depression or anxiety, 60 of whom had used pharmacotherapy for such at some time and 40 were actively using anxiolytics or anti-depressants at time of evaluation. No patient had a history of neurological conditions and neurological exam was normal in all. Mean duration of symptoms was 14 ± 20 months. Median number of prior physician consultations was 1 (1,4). All complained of impaired erectile function, 50% being incapable of having penetrative sexual relations. 91% had or were using PDE5 inhibitors. On examination all patients had a hypertonic flaccid penis with excellent stretch on traction. At PDDU, median number of penile injections was 2 (1, 3). 50% of men required phenylephrine reversal. All patients had normal PSV with 2/88 having abnormal EDV values, both of whom required reversal. Mean PSV was 45±35 cm/s, mean EDV was 2±11 cm/s. No patient had elevated echogenicity on B-mode scanning. CONCLUSIONS: In this analysis, all men presenting with self-reported HFS had normal hemodynamics and an absence of fibrosis, suggesting the absence of vascular or gross cavernosal smooth muscle structural changes. Source of Funding: none © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e334 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information John Sullivan More articles by this author Carolyn Salter More articles by this author Jose Flores More articles by this author Pat Guhring More articles by this author Marilyn Parker More articles by this author John Mulhall More articles by this author Expand All Advertisement PDF DownloadLoading ...

Rejuvenation of the ageing face and the role of orthodontics: Guidelines for management

The article reviews the ageing changes of the midfacial and maxillary bones, the mandible, the overlaying soft tissues and the smile, and presents clinical guidelines aiming to rejuvenate older faces by means of orthodontic therapy. With regard to the ageing changes, the maxillary skeleton appears to rotate clockwise inferior to the orbit and becomes retrusive, and as a general pattern the midface contracts and deteriorates with age. Resorption below the mental foramen, reduction in alveolar height, loss of bone at the chin region, and relative increase in size and shape are signs of an aged mandible. Epidermal thinning and decrease in collagen in combination with the effect of gravity and various external factors contribute to the ageing of the skin. Atrophy of the superficial and deep fat, changes in ligamentous tissues and changes in muscle structure, position and tone, all contribute to the stigmata of the aged face. In the article, two late adulthood orthodontic cases are discussed as examples, and general guidelines for orthodontic management of the older face aiming at reversing the 'shrinkage' of the tissues by restoring the facial shape and tightening the soft tissue mask are described. The possible mechanisms explaining the changes observed on the faces of the clinical cases are also discussed. A properly planned and executed orthodontic intervention reversing changes from the inside-out before embarking on cosmetic surgery might have a synergistic effect multiplying the benefits for adult patients.

Intracavernous Injection of Botulinum Toxin may Improve Erectile Function in a Bilateral Cavernous Nerve Injury Animal Model

ABSTRACT Introduction Erectile dysfunction (ED) is common after treatments for prostate cancer, such as radical prostatectomy (RP) and can negatively impact both patient and partner quality of life. Botulinum toxin (Botox) promotes smooth muscle relaxation and may augment erectile function by reducing basal sympathetic tone in the corpora cavernosa. Botox utilization has suggested a neuroprotective and nerve regenerative role after peripheral nerve injury. Objective We investigated Botox as a durable treatment option for ED in a bilateral cavernous nerve injury (BCNI) animal model. We evaluated the structural changes in penile smooth muscle after intracavernous injection of Botox in an animal model of post-RP ED. Methods Sixteen Sprague Dawley rats (4.5months; 450-550g) were randomized to 4 groups: (1) Sham + NS (2) BCNI + NS (3) Sham + Botox (4) BCNI + Botox. When cavernous nerves were identified during surgery, they were either crushed (BCNI) or left untouched (Sham). Next, either 10 units of Botox or 80umL of normal saline (NS) were injected into the corpora cavernosa. On day 14, erectile function was assessed via cavernous nerve electro-stimulation induced intracavernous pressure (ICP) changes. Penile tissue was harvested for immunohistochemistry and Western blot for neuronal nitric oxide synthase (nNOS) and smooth muscle α-actin (SMA). Results Fourteen animals were included for analysis; one animal in groups 2 and 3 were euthanized for weight loss and lethargy. The Botox treatment groups had a net weight loss whereas the NS groups had weight gain (p<0.05). Erectile function after BCNI recovered with Botox injections and both group 3 & 4 had mean peak ICP and area under the curve values analogous to baseline (group 1) and statistically improved compared to control (group 2) (Figure 1). Western blot analysis revealed a recovery of both nNOS and SMA after Botox treatment (P=0.06). Conclusions This is the first animal study evaluating intracavernous Botox injections for treating ED after BCNI and compared to placebo, the intervention appears to recover erectile function. Further preclinical studies are needed to support this finding, but there may be a future role for using Botox to treat post-prostatectomy ED. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: boston scientific

Influence of Heat on Protein Degradation, Histology and Eating Quality Indicators of Chicken Meat

The experiments were carried out during February–July, 2021 at the Department of Livestock Products Technology (Meat science), Veterinary College and Research Institute, Namakkal, Tamil Nadu Veterinary and Animal Sciences University, India to assess the influence of heat on protein degradation, histology and eating quality indicators of chicken. Meat samples were taken from the broiler breast and cooked for the targeted end point temperature (75°C, 83°C, 89°C and 94°C) then assessed pH, colour, cooking loss, shear force value, protein degradation (SDS PAGE) and structure of muscle fibers. The heating temperature had a significant effect on pH and shear force value (p<0.01) at 94°C. Colour L* decreased significantly (p<0.01) and a* and b* value increased significantly (p<0.01) of cooked chicken breast at increasing end point cooking temperature. Progressive increasing (p<0.01) trends of cooking loss were noticed during the rising of end point cooking temperature. There were no significant differences between muscle fiber diameters. But significant (p<0.01) differences were observed in the sarcomere length of cooked chicken meat, showing decreasing trends during increasing temperature. Analysis of SDS-PAGE showed that the intensity of the myofibrillar protein band gradually decreased during chicken meat cooking at a higher endpoint temperature and inferring that the meat protein had changed. The heating temperature had a significant effect on sensory quality of cooked chicken breast at increasing end point cooking temperature. This study revealed that meat cooking at high-end point temperatures affects the meat quality by degradation of muscle proteins and changes in muscle structure.

Microvascular Permeability and Texture Analysis of the Skeletal Muscle of Diabetic Rabbits With Critical Limb Ischaemia Based on DCE-MRI

BackgroundWe evaluated skeletal muscle vascular permeability in diabetic rabbits with critical limb ischaemia using quantitative dynamic contrast agent-enhanced (DCE) magnetic resonance imaging (MRI) and explored the feasibility of using DCE-MRI Ktrans-based texture analysis for assessing early slight ischaemia-related skeletal muscle structural changes.MethodTwenty-four male New Zealand white rabbits (2.7 ± 0.3 kg; n = 12 each in sham-operated and experimental groups) underwent axial MRI of the vastus lateralis muscle at 1, 2, and 3 weeks after alloxan injection. Between-group and intra-group postoperative permeability and texture parameters were compared. Texture features of experimental groups in the third week were modelled by receiver operating characteristic (ROC) curve analysis. Correlations of permeability and of statistical texture parameters with peripheral blood endothelial progenitor cells (EPCs) and microvascular density (MVD) were analysed.ResultsIn the experimental group, the transfer constant (Ktrans) was statistically significant at all time-points (F = 5.800, P = 0.009). Their vastus lateralis muscle Ktrans was significantly lower in the third than in the first week (P = 0.018) and correlated positively with peripheral blood EPCs in the experimental group [r = 0.598, (95% CI: 0.256, 0.807)]. The rate constant was negatively associated with vastus lateralis muscle MVD [r = -0.410, (95% CI: -0.698, -0.008)]. The area under the ROC curve of texture parameters based on Ktrans in ischaemic limbs was 0.882.ConclusionsQuantitative DCE-MRI parameters could evaluate microvascular permeability of ischaemic limb skeletal muscle, and texture analysis based on DCE-MRI Ktrans allowed evaluation of early slight skeletal muscle structural changes.

Acute Ultrasonographic Changes in Lower Extremity Muscle Structure after Motor Complete Spinal Cord Injury.

There is a lack of studies examining ultrasonographic muscle changes in patients with acute spinal cord injury (SCI). We recruited adults with motor complete acute SCI and performed longitudinal ultrasound measurements. The primary outcome measures were rectus femoris and medial gastrocnemius thickness and echo intensity. This study recruited 20 patients, with a mean time to the first ultrasound measurement of 17.2 ± 2.14 days, with the second measurement done 4 weeks after the first measurement. We found that there was a mean decrease in the rectus femoris muscle thickness of 18.7% (P = 0.027), as well as a mean increase in the rectus femoris echo intensity of 13.0 a.u. (P = 0.009), although no significant differences were found for the medial gastrocnemius. This study demonstrates decreased thickness and increased echo intensity in the rectus femoris but not in the medial gastrocnemius in patients with motor complete SCI.

Quantity versus quality: Age-related differences in muscle volume, intramuscular fat, and mechanical properties in the triceps surae.

With aging comes reductions in the quality and size of skeletal muscle. These changes influence the force-generating capacity of skeletal muscle and contribute to movement deficits that accompany aging. Although declines in strength remain a significant barrier to mobility in older adults, the association between age-related changes in muscle structure and function remain unresolved. In this study, we compared age-related differences in (i) muscle volume and architecture, (ii) the quantity and distribution of intramuscular fat, and (iii) muscle shear modulus (an index of stiffness) in the triceps surae in 21 younger (24.6±4.3years) and 15 older (70.4±2.4years) healthy adults. Additionally, we explored the relationship between muscle volume, architecture, intramuscular fat and ankle plantar flexion strength in young and older adults. Magnetic resonance imaging was used to determine muscle volume and intramuscular fat content. B-mode ultrasound was used to quantify muscle architecture, shear-wave elastography was used to measure shear modulus, and ankle strength was measured during maximal isometric plantar flexion contractions. We found that older adults displayed higher levels of intramuscular fat yet similar muscle volumes in the medial (MG) and lateral gastrocnemius (LG) and soleus, compared to younger adults. These age-related higher levels of intramuscular fat were associated with lower muscle shear modulus in the LG and MG. We also found that muscle physiological cross-sectional area (PCSA) that accounted for age-associated differences in intramuscular fat showed a modest increase in its association with ankle strength compared to PCSA that did not account for fat content. This highlights that skeletal muscle fat infiltration plays a role in age-related strength deficits, but does not fully explain the age-related loss in muscle strength, suggesting that other factors play a more significant role.

Injection of Micronized Human Amnion/Chorion Membrane Results in Increased Early Supraspinatus Muscle Regeneration in a Chronic Model of Rotator Cuff Tear.

Surgical repair of severe rotator cuff tear often results in retear due to unaddressed muscle degeneration. The objective of this study was to test the regenerative potential of micronized dehydrated Human Amnion/Chorion Membrane (dHACM), in a clinically relevant delayed reattachment model of rotator cuff repair. Micronized dHACM was injected into rat supraspinatus muscle during tendon re-attachment surgery, three weeks after original tendon injury. One week after material injection, inflammatory and mesenchymal stem cell infiltration into supraspinatus muscles was assessed via flow cytometry. Histological methods were utilized to assess structural and regenerative changes in muscle one and three weeks after material injection. Micronized dHACM injection resulted in increased M1-like macrophages (17.1 [Formula: see text] fold change over contralateral controls) and regenerating muscle fibers (4.3% vs 1.7% in saline treated muscles) one week after injection compared to saline treated muscles. Tendon reattachment itself exhibited intrinsic healing in this model, demonstrated by a general return of muscle weight and reduced fibrosis. Our results indicate that injection of micronized dHACM may initiate an inflammatory response in degenerated muscle that promotes early muscle regeneration, and that our animal model may be a suitable platform for studying treatments in muscle at early timepoints, before intrinsic healing occurs.

Development of DTI Based Probabilistic Tractography Methods to Characterize Arm Muscle Architecture in Individuals Post Hemiparetic Stroke.

A hemiparetic stroke may lead to changes in muscle structure that further exacerbate motor impairments of the paretic limb. Cadaveric measurements have previously been used to study structural parameters in skeletal muscles but has several limitations, including ex vivo fixation. Here, we present novel application of diffusion tensor imaging (DTI) based probabilistic tractography methods, in comparison to the traditional deterministic approach, with respect to cadaveric dissection to quantify in vivo muscle fascicles in the biceps brachii. Preliminary results show that probabilistic tractography yields longer fascicle lengths that are more consistent with cadaveric measurements, albeit with higher variability, while deterministic tractography identifies shorter fascicle lengths, but with less variability. Results suggest that DTI tractography techniques can capture fascicles consistent with previously published cadaveric measurements and can identify interlimb differences in fascicle lengths in an individual with stroke.Clinical Relevance- The methods proposed here describe a non-invasive way to quantify heterogeneous musculoskeletal parameters such as across upper arm muscles in individuals with hemiparetic stroke. This will expand the current knowledge of macro- and micro-structural muscle changes that occur after stroke and may lead to more effective rehabilitation strategies to prevent such changes in individuals with stroke.

Relationship between structural changes in paravertebral muscles and the development of spine degenerative diseases

Based on the systematic approach to the diagnosis of spinal patho­logy, there are no fundamental differences in the etiology of spine degenerative disease, facet joints arthritis, and other diseases. These diseases are considered multifactorial: age (aging), systemic regulatory factors (hormones, peptides, cytokines), genetic predisposition, inadequate physical activity, unfavorable environmental factors, and others lead to pathological changes in the structure of the spinal motor segment components. Recently, much attention has been paid to the paravertebral muscles changes, in which over time, as a result of injuries or degenerative processes, inevitably lead to dysfunction, which can lead to the occurrence of chronic lumbar pain. Objective. To assess the relationship between structural changes in paravertebral muscles and the development of degenerative diseases of the spine on the basis of scientific literature review. It was found that degenerative changes in paravertebral muscles, as components of spinal motor segments, develop with aging. In particular, muscle fibers are replaced by fat tissue, which is more pronounced in women compared to men. A direct correlation between chronic lumbar pain and paravertebral muscle atrophy has been reported. Systemic factors, in particular low levels of vitamin D, also can cause the development of degenerative changes in paravertebral muscles, especially in women. Obesity provokes systemic inflammation, increases fatty infiltration of skeletal muscles and increases sensitivity to pain. Reduced levels of physical activity lead to weakness and atrophy of the paravertebral muscles, which can cause degeneration of the intervertebral disc. At the same time, exercise prior to spinal surgery for degenerative disea­ses improves functional outcomes and reduces pain. Conversely, damage to the paravertebral muscles increase the load on the adjacent to spinal fusion segments. In general, the role of paravertebral muscles in the development of degenerative spinal diseases has not been definitively studied.

Kynurenine as a potential biomarker in detecting reduced muscle endurance: metabolomic profiling of patients with heart failure and exercise intolerance

Abstract Aims Reduced muscle endurance (RME) in patients with HFpEF and HFrEF is associated with structural and metabolic changes in skeletal muscle. We investigated the role of kynurenine (Kyn) as a potential marker in detecting RME. Additionally, we described the likely distorted metabolic pathways in serum in patients with RME and both preserved (HFpEF) and reduced (HFrEF) ejection fraction. Methods Fifty-five participants were prospectively recruited (17 HFpEF, 18 HFrEF outpatients and 20 healthy controls, HC). All participants underwent echocardiography, CPET, isokinetic muscle function tests. Quantification of metabolites in serum was performed using liquid chromatography tandem mass spectrometry. Results In a linear regression, Kyn was an independent predictor for RME after adjusting for alanine, glutamate, ornithine, spermine and short-chain-ACs (B: −8.2 per 1μM increase, 95% CI: −13.01, −3.30, p=0.001). Kyn showed 83% sensitivity and 70% specificity (area under the curve 0.83) in detecting RME. Patients with RME and HFpEF showed reduced levels of long-chain-, medium-chain-, medium-/long-chain-ACs ratios and alanine (p<0.05). In patients with RME and HFrEF we observed reduced concentrations of AAs (p<0.05). Compared to HC, patients with HFpEF and HFrEF had reduced amino acid (AA)-concentrations except for branched-chain and aromatic AAs, and higher concentrations of acylcarnitines (ACs) and Kyn (p<0.05). Conclusions Kyn shows high potential as biomarker for detecting RME. RME was associated with impaired fatty acid oxidation rates in HFpEF patients and with reduced concentrations of AAs in those with HFrEF. Funding Acknowledgement Type of funding sources: None.

Effect of Morin on fluoxetine (Prozac)-induced structural changes of mice skeletal muscle: light and electron microscopic study

Effect of Morin on fluoxetine (Prozac)-induced structural changes of mice skeletal muscle: light and electron microscopic study

Evaluating the failure to bloom in dark-cutting and lactate-enhanced beef longissimus steaks

Previous studies have noted lower L* (lightness) values for both dark-cutting beef and normal-pH beef enhanced with lactate. In the current study, absorption-coefficient, scattering-coefficient, CIE L*a*b* values, refractive index of sarcoplasm, and inter-muscle bundle space were evaluated for dark-cutting beef, normal-pH beef enhanced with lactate, normal-pH beef enhanced with water, and normal-pH beef not enhanced with either water or lactate. Compared with non-enhanced loins, lactate-enhancement had lower a*, chroma, oxymyoglobin, reflectance, scattering, and inter-muscle bundle space as well as greater absorption and refractive index. Dark-cutting steaks had lower a*, chroma, oxymyoglobin values, reflectance, and scattering as well as less inter-muscle bundle space compared with lactate-enhanced steaks. Sarcoplasm refractive index values were greater in lactate-enhanced steaks than dark-cutting steaks. The results suggest that changes in muscle structure and optical properties due to either pH or lactate addition can alter muscle darkening and blooming properties.

Bioelectrical impedance (BIA)-derived phase angle in adults with obesity: A systematic review

Bioimpedance analysis-derived phase angle (PhA), as marker of body cell mass and cell integrity, might be altered in obesity, a condition which is characterized by alterations in muscle structure and function. The aim of this systematic review was to evaluate whether and to which extent PhA varies in individuals/patients with excess body weight focusing on: a) changes in PhA due to obesity; b) changes in PhA after bariatric interventions or training programs.According to PRISMA criteria, a systematic literature search until February 2021 using PubMed, Embase, Scopus, and Web of Science was performed. Selection criteria included studies on patients with obesity without comorbidities other than metabolic diseases.A total of 278 articles were first identified. After removing duplicates and excluding studies that did not fulfil the inclusion criteria, the full text of the remaining 80 potentially relevant studies was examined to finally retrieve 11 cross-sectional and 10 longitudinal studies. Few studies have shown that PhA is lower in individuals/patients with obesity than in controls. The only study on the matter showed a decrease with age after the fourth decade of life. Four out of five studies reported consistently greater mean values in men than in women. In two studies PhA was lower in patients with severe obesity; in addition, Patients with low PhA had higher BMI and PhA was inversely correlated with fat mass. Longitudinal studies showed that PhA markedly decreased after bariatric surgery and slightly increased after training programs.Thus, a relatively low number of studies have evaluated PhA in individuals/patients with obesity with sometimes contradictory and preliminary results. PhA might be useful to evaluate muscle quality in individuals/patients with obesity but further studies are needed to more accurately associate this variable with changes in muscle structure and strength, as well as in metabolic functions.

Age-dependent mechanical and microstructural properties of the rabbit soleus muscle

During growth there are serious changes in the skeletal muscles to compensate for the changed requirements in terms of body weight and size. In this study, the age-dependent (between 21 and 100 days) mechanical and microstructural properties of rabbit soleus muscle tissue were investigated. For this purpose, morphological properties (animal mass, soleus muscle mass, tibial length) were measured at 5 different times during aging. On the other hand, fibre orientation-dependent axial and semi-confined compression experiments were realised. In addition, the essential components (muscle fibres, extracellular matrix, remaining components), dominating the microstructure of muscle tissue, were analysed. While the mechanical results show hardly any age-dependent differences, the morphological and microstructural results show clear age-dependent differences. All morphological parameters increase significantly (animal mass by 839.2%, muscle mass 1050.6%, tibial length 233.6%). In contrast, microstructural parameters change differently. The percentage of fibres (divided into slow-twitch (ST) and fast-twitch (FT) fibres) increases significantly (137.6%), while the proportions of the extracellular matrix and the remaining components (48.2% and 46.1%) decrease. At the same time, the cross-sectional area of the fibres increases significantly (697.9%). The totality of this age-dependent information provides a deeper understanding of age-related changes in muscle structure and function and may contribute to successful development and validation of growth models in the future. Statement of significanceThis article reports the first comprehensive data set on age-dependent morphological (animal mass, soleus muscle mass, tibial length), mechanical (axial and semi-confined compression), and microstructural (muscle fibres, extracellular matrix, remaining components) properties of the rabbit soleus muscle. On the one hand, the results of this study contribute to the understanding of muscle mechanics and thus to understanding of load transfer mechanisms inside the muscle tissue during growth. On the other hand, these results are relevant to the fields of constitutive formulation of age-dependent muscle tissue.

Botox Injections in Paraspinal Muscles Result in Low Maximal Specific Force and Shortening Velocity in Fast but Not Slow Skinned Muscle Fibers.

Basic science, experimental animal study. To determine the effects of Botulinum toxin type A (BTX-A) injections on the mechanical properties of skinned muscle fibers (cells) of rabbit paraspinal muscles. BTX-A has been widely used in the treatment of disorders of muscle hyperactivity, such as spasticity, dystonia, and back pain. However, BTX-A injection has been shown to cause muscle atrophy, fat infiltration, and decreased force output in target muscles, but its potential effects on the contractile machinery and force production on the cellular level remain unknown. Nineteen-month-old, male New Zealand White Rabbits received either saline or BTX-A injections into the paraspinal muscles, equally distributed along the left and right sides of the spine at T12, L1, and L2 at 0, 8, 12, 16, 20, and 24 weeks. Magnetic resonance imaging was used to quantify muscle crosssectional area and structural changes before and at 28 weeks following the initial injection. Skinned fibers isolated from the paraspinal muscles were tested for their active and passive force-length relationships, unloaded shortening velocity, and myosin heavy chain isoforms. BTX-A injections led to significant fat infiltration within the injected muscles and a greater proportion of IIa to IIx fibers. Isolated fast fibers from BTX-A injected animals had lower active force and unloaded shortening velocity compared with fibers from saline-injected control animals. Force and velocity properties were not different between groups for the slow fibers. Injection of BTX-A into the paraspinal rabbit muscles leads to significant alterations in the contractile properties of fast, but not slow, fibers.Level of Evidence: N/A.

Structural and Metabolic Changes in Skeletal Muscles of Patients with Chronic Disorders of Consciousness—To the Issue of Critical Illness Polyneuromyopathies (a PET/CT Pathomorphological Study)

Structural and Metabolic Changes in Skeletal Muscles of Patients with Chronic Disorders of Consciousness—To the Issue of Critical Illness Polyneuromyopathies (a PET/CT Pathomorphological Study)

Morphological changes and functional circRNAs screening of rabbit skeletal muscle development

BackgroundThe temporal expression pattern of circular RNAs (circRNAs) across developmental stages is essential for skeletal muscle growth and functional analysis. However, there are few analyses on the potential functions of circRNAs in rabbit skeletal muscle development.ResultsInitially, the paraffin sections showed extremely significant differences in the diameter, number, area and density of skeletal muscle fibers of the fetus, child, adult rabbit hind legs (P < 0.01). Then, RNA-seq libraries of these three stages were constructed. A total of 481 differentially expressed circRNAs (DE-circRNAs) and 5,658 differentially expressed genes (DEGs) were identified. Subsequently, DE-circRNAs, whose host genes were DEGs or non-DEGs, were analyzed by GO respectively. In the fetus vs. child group, up-regulated DE-circRNAs (whose host genes were DEGs) were related to muscle fiber structure, and down-regulated ones were related to mitosis. The up-regulated DE-circRNAs (whose host genes were non-DEGs) were involved in enzyme activity, methylation and glycosylation, and the down-regulated ones were involved in mitosis and catabolism. In the fetus vs. adult group, the up-regulated DE-circRNAs (whose host genes were DEGs) were related to skeletal muscle basic structure, and the down-regulated ones were also associated with cell proliferation. But the up-regulated DE-circRNAs (whose host genes were non-DEGs) were connected with regulation of histone ubiquitination, chromatin and organelles. The down-regulated DE-circRNAs were connected with the catabolism processes. In addition, novel_circ_0022663 and novel_circ_0005489, which might have coding potential, and novel_circ_0004210 and novel_circ_0001669, which might have miRNA sponge capability, were screened out.ConclusionsIn this study, hind leg muscles of fetus, child and adult rabbits were collected for paraffin section and RNA-seq to observe the structural changes of skeletal muscle and obtain circRNA expression profiles at different stages. These data provided a catalog of circRNAs related to muscle development in New Zealand rabbits, allowing us to better understand the functional transitions in mammalian muscle development.

Gastrocnemius Muscle Structural and Functional Changes Associated with Domestication in the Turkey.

Simple SummaryDomestic turkeys have been bred to reach a body mass of up to three times that of wild turkeys. Most of this increase is from larger muscles, but it is unclear exactly how the components of each muscle have been altered and what that may mean for muscle function. In this study, we looked for potential differences between wild and domestic turkeys in (1) the size of the individual muscle fibers and (2) the collagenous skeleton that supports those fibers in the lateral gastrocnemius muscle, an ankle extensor important for walking. We also measured the force this muscle could produce. The domestic turkey muscle had a greater number of smaller muscle fibers than the wild turkey. The amount of collagen in the domestic turkey muscle was also lower than wild turkeys, likely contributing to meat tenderness. While the domestic turkey lateral gastrocnemius muscles could produce the same amount of force per a given area of muscle, they could only produce half as much force per unit body mass. Selection for increased muscle mass has altered the structure of the lateral gastrocnemius muscle; however, overall body mass likely contributes more to hind limb functional differences observed in the domestic turkey.Selection for increased muscle mass in domestic turkeys has resulted in muscles twice the size of those found in wild turkeys. This study characterizes muscle structural changes as well as functional differences in muscle performance associated with selection for increased muscle mass. We compared peak isometric force production, whole muscle and individual fiber cross-sectional area (CSA), connective tissue collagen concentration and structure of the lateral gastrocnemius (LG) muscle in wild and adult domestic turkeys. We also explored changes with age between juvenile and adult domestic turkeys. We found that the domestic turkey’s LG muscle can produce the same force per cross-sectional area as a wild turkey; however, due to scaling, domestic adults produce less force per unit body mass. Domestic turkey muscle fibers were slightly smaller in CSA (3802 ± 2223 μm2) than those of the wild turkey (4014 ± 1831 μm2, p = 0.013), indicating that the absolutely larger domestic turkey muscles are a result of an increased number of smaller fibers. Collagen concentration in domestic turkey muscle (4.19 ± 1.58 μg hydroxyproline/mg muscle) was significantly lower than in the wild turkeys (6.23 ± 0.63 μg/mg, p = 0.0275), with visible differences in endomysium texture, observed via scanning electron microscopy. Selection for increased muscle mass has altered the structure of the LG muscle; however, scaling likely contributes more to hind limb functional differences observed in the domestic turkey.