Muscle Type Research Articles

Evaluation of the relationship between the attachment type of lateral pterygoid muscle and the position of temporomandibular joint disc in patients with temporomandibular joint disorders based on wireless amplified MRI detector high resolution imaging

Objective: To explore the correlation between the attachment type of lateral pterygoid muscle (LPM) and the position of temporomandibular joint (TMJ) disc in patients with temporomandibular disorders (TMD) by using wireless amplified magnetic resonance imaging detector (WAND) coupled with conventional head and neck joint coil for high resolution imaging of TMJ. Methods: Eighty-five patients with TMD diagnosed by oral and maxillofacial surgeons of Guizhou Provincial People's Hospital from October 2019 to January 2022 were collected. A total of 160 TMJ were included. There were 16 males and 69 females, aged (32.7±14.2) years. All patients were scanned with open, closed oblique sagittal and coronal WAND coupled head and neck coils with bilateral TMJ. Based on TMJ and LPM high resolution imaging, to explore the correlation between LPM attachment types and the position of TMJ disc in TMD patients, and to evaluate the potential clinical value of LPM attachment types in TMD patients. χ2 test and Pearson correlation analysis were used to evaluate the correlation between LPM attachment type and TMJ disc location. Results: There were three types of LPM attachment: type Ⅰ in 51 cases [31.9% (51/160)], type Ⅱ in 77 cases [48.1% (77/160)] and type Ⅲ in 32 cases [20.0% (32/160)]. There was a significant correlation between the type of LPM attachment and the position of articular disc (χ2=28.20, P=0.002, r=0.776). There was no statistical significance between the type of LPM attachment and the reversible displacement of articular disc (χ2=0.24, P=0.887, r=0.825). Conclusions: There is a correlation between the attachment type of LPM and the position of the disc in TMD patients. WNAD coupled with conventional head and neck joint coil TMJ high resolution scan can provide reliable imaging evidence for TMD patients in evaluating the type of LPM attachment and the location of disc.

Accessory Subscapularis muscle compressing posterior division of upper trunk: A rare presentation

Presence of additional or accessory muscles near the axilla can lead to compression of vital structures of the axilla. Opposite conventional thoughts, it seems that the subscapularis muscle (SM) is the most variable muscle of the rotator cuff group. Accessory Subscapularis muscle is one of the rare variants of the Subscapularis muscle. Presence of this variant (ASsm) can cause abnormal clinical presentation. During routine dissection of the axilla in a female cadaver in the Department of Anatomy, Muzaffarnagar Medical College, we found an additional slip or accessory subscapularis muscle, arising from the anterolateral part of the Subscapularis and running upward and medially, finally attached to the coracoid process (palpated tip). During its course, it passed through the Brachial plexus and caused compression of the posterior division of the Upper trunk. This type of accessory slip or accessory subscapular muscle can cause compression neuropathy, or this accessory slip can be used during the repair of a ruptured Subscapularis or any other adjacent muscle. Keywords: Accessory Subscapularis Muscle, Rotator Cuff Variants, Brachial Plexus Compression

Proteomics and metabolomics profiling of meat exudate to determine the impact of postmortem aging on oxidative stability of beef muscles.

The objective of this study was to characterize the major proteomes and metabolites in beef exudate and determine their relationship to color and oxidative quality of beef muscles. Beef loin (LD) and tenderloin (PM) muscles were cut into sections, individually vacuum-packaged, and aged for 9, 16 and 23days at 2°C. Following aging, beef exudates were collected and analyzed for both proteomics and metabolomics profiles. Proteome analysis indicated clustering by muscle types, while metabolomics profiling further clustered the samples based on the aging periods. The PM exudate had a greater concentration of oxidative enzymes, while the LD exudate contained more glycolytic enzymes. Greater lipid, nucleotide, carnitine and glucoside metabolites were observed in LD and 23d exudates. HSP70 and laminin proteins, together with glucosides metabolites, were correlated to muscle oxidative stability. The results indicated that meat exudate could be a viable analytical matrix to determine changes in quality attributes of meat with aging.

Meta-Regression Analysis of Relationships between Fibre Type and Meat Quality in Beef and Pork-Focus on Pork.

This meta-regression analysis was conducted to identify the relationship between fibretype cross-sectional area (CSA) and frequency (%) and meat quality traits, especially tenderness (sensory and Warner-Bratzler Shear Force, WBSF). Literature searches were conducted using specific keywords which resulted in 32 peer-reviewed manuscripts that contained averages and correlation coefficients for fibre type (frequency and CSA) and quality traits of longissimus muscle for beef and pork (7 and 25 studies respectively). Correlations were analysed in meta-regression using R-Studio and linear regression was also conducted. For the combined beef and pork analysis, only pH, WBSF, and drip loss were associated with fibre type frequency and CSA (p < 0.05 for all). Limiting the analysis to pork, the key results were frequency of type I fibres were associated with decreased drip loss, increased cook loss, decreased lightness (L*) and increased sensory tenderness whereas frequency of type IIb fibres were associated with increased drip loss (p < 0.05 for all). In addition, the CSA of type I and IIb fibres was associated with colour traits lightness and redness (p < 0.05 for all). Future research should focus on fibre type across breeds and muscles to further understand the impacts of fibre type frequency and CSA on quality.

Cryo-EM structure of the folded-back state of human β-cardiac myosin

To save energy and precisely regulate cardiac contractility, cardiac muscle myosin heads are sequestered in an ‘off’ state that can be converted to an ‘on’ state when exertion is increased. The ‘off’ state is equated with a folded-back structure known as the interacting-heads motif (IHM), which is a regulatory feature of all class-2 muscle and non-muscle myosins. We report here the human β-cardiac myosin IHM structure determined by cryo-electron microscopy to 3.6 Å resolution, providing details of all the interfaces stabilizing the ‘off’ state. The structure shows that these interfaces are hot spots of hypertrophic cardiomyopathy mutations that are thought to cause hypercontractility by destabilizing the ‘off’ state. Importantly, the cardiac and smooth muscle myosin IHM structures dramatically differ, providing structural evidence for the divergent physiological regulation of these muscle types. The cardiac IHM structure will facilitate development of clinically useful new molecules that modulate IHM stability.

Lymphocyte-Specific Protein Tyrosine Kinase Contributes to Spontaneous Regression of Liver Fibrosis mayby Interacting with Suppressor of Cytokine Signaling 1.

Quiescent hepatic stellate cells (qHSCs), converted to myofibroblasts, produce fibrous scars, which is an essential event during liver fibrogenesis. Clinical and experimental fibrosis undergo remarkable regression when the underlying etiological agent is removed. Some myofibroblasts revert to an inactive phenotype (iHSCs) during the regression of fibrosis. However, the mechanisms underlying HSC activation and reversal remain unclear. The present study demonstrated that the expression of lymphocyte-specific protein tyrosine kinase (LCK) was increased in fibrotic livers but decreased after spontaneous recovery in vivo and in vitro, which was correlated with the expression of α-smooth muscle actin (α-SMA) and type I collagen (COL-1). Further investigation indicated that specific knockdown of LCK by a recombination adeno-associated virus 9 (rAAV9) in C57BL/6 mice ameliorated liver fibrosis. Co-incubation of TGF-β1-induced HSC-T6 cells with LCK-siRNA inhibited cell proliferation and activation. Overexpression of LCK inhibited activated HSCs going to inactivated phenotype. Interestingly, we found that LCK may interact with suppressor of cytokine signaling 1 (SOCS1) and may influence the expression of p-JAK1 and p-STAT1/3. These data suggest that LCK may play a regulatory role in liver fibrosis by inhibiting SOCS1, indicating that LCK is a potential therapeutic target for liver fibrosis treatment.

Carcass characteristics and meat quality of Holstein bulls depending on slaughter age and muscle types

Carcass characteristics and meat quality of Holstein bulls depending on slaughter age and muscle types

Advanced Methodology for Rapid Isolation of Single Myofibers from Flexor Digitorum Brevis Muscle.

Isolated individual myofibers are valuable experimental models that can be used in various conditions to understand skeletal muscle physiology and pathophysiology at the tissue and cellular level. This report details a time- and cost-effective method for isolation of single myofibers from the flexor digitorum brevis (FDB) muscle in both young and aged mice. The FDB muscle was chosen for its documented history in single myofiber experiments. By modifying published methods for FDB myofiber isolation, we have optimized the protocol by first separating FDB muscle into individual bundles before the digestion, followed by optimizing the subsequent digestion medium conditions to ensure reproducibility. Morphological and functional assessments demonstrate a high yield of isolated FDB myofibers with sarcolemma integrity achieved in a shorter time frame than previous published procedures. This method could be also adapted to other types of skeletal muscle. Additionally, this highly reproducible method can greatly reduce the number of animals needed to yield adequate numbers of myofibers for experiments. Thus, this advanced method for myofiber isolation has the potential to accelerate research in skeletal muscle physiology and screening potential therapeutics "ex vivo" for muscle diseases and regeneration.

Schizandrin C regulates lipid metabolism and inflammation in liver fibrosis by NF-κB and p38/ERK MAPK signaling pathways.

Liver fibrosis is considered a sustained wound healing response and metabolic syndrome, and its therapy is of great significance for chronic liver disease. Schizandrin C, as one lignan from hepatic protectant Schisandra chinensis, can depress the oxidative effect and lipid peroxidation, and protect against liver injury. In this study, C57BL/6J mice were used to estimate a liver fibrosis model by CCl4, and Schizandrin C exerted an anti-hepatic fibrosis effect, as evidenced by decreased alanine aminotransferase, aspartate aminotransferase and total bilirubin activities in serum, lower hydroxyproline content, recuperative structure and less collagen accumulation in the liver. In addition, Schizandrin C reduced the expressions of alpha-smooth muscle actin and type Ι collagen in the liver. In vitro experiments also revealed that Schizandrin C attenuated hepatic stellate cell activation in both LX-2 and HSC-T6 cells. Furthermore, lipidomics and quantitative real-time PCR analysis revealed that Schizandrin C regulated the lipid profile and related metabolic enzymes in the liver. In addition, the mRNA levels of inflammation factors were downregulated by Schizandrin C treatment, accompanied by lower protein levels of IκB-Kinase-β, nuclear factor kappa-B p65, and phospho-nuclear factor kappa-B p65. Finally, Schizandrin C inhibited the phosphorylation of p38 MAP kinase and extracellular signal-regulated protein kinase, which were activated in the CCl4 fibrotic liver. Taken together, Schizandrin C can regulate lipid metabolism and inflammation to ameliorate liver fibrosis by nuclear factor kappa-B and p38/ERK MAPK signaling pathways. These findings supported Schizandrin C as a potential drug for liver fibrosis.

An Exploration of the Anatomy of the Forehead of Asians and Its Relationship With Forehead Lines Based on Ultrasound Imaging.

A profound understanding of the various frontal tissues' morphology and their relationship with forehead lines can efficiently guide clinical treatment. The authors explored the relationship between frontal anatomy and frontal lines. We measured the thickness and shape of tissues in different regions of the forehead of 241 Asians. Then, we analyzed the relationship between the types of frontalis muscle and frontal lines, as well as the relationship between the frontal anatomical structures and the production of frontal lines. We classified the types of frontalis muscle into 3 categories comprising 10 subtypes. The skin (0.78 mm vs 0.90 mm, P < .05), superficial subcutaneous tissue (0.66 mm vs 0.75 mm, P < .05), and frontalis muscle thickness (0.29 mm vs 0.37 mm, P < .05) of people with obvious dynamic forehead lines were significantly thicker than those of people without significant dynamic forehead lines. However, no significant difference in the deep subcutaneous tissue thickness was found between people with and without static forehead lines (1.36 mm vs 1.34 mm, P < .05). This study shows the relationship between the frontal structure and frontal lines. Therefore, these results can provide references for treating frontal lines, to a certain extent.

CHEMICAL COMPOSITION AND AMINO ACID PROFILE OF GOOSE MEAT (UKRAINIAN LARGE GRAY AND LARGE WHITE BREEDS) IN SEMI-INTENSIVE SYSTEM OF GROWING

Large gray and Large white geese breeds were created in Ukraine and are widespread. At the same time, the nutritional value of their meat is insufficiently studied. Therefore, this work aimed to study and compare the chemical composition and amino acid profile of the muscles of the chest and thighs of geese of these breeds in semi-intensive growing. The study used 20 heads of geese of both sexes of the Large gray and Large white breeds, which were raised under similar housing and feeding conditions. Muscle samples were analyzed following current regulations in Ukraine, harmonized with relevant international standards. Studies have shown no significant differences in the muscle content of males and females of these breeds in terms of moisture, protein and ash, but a more significant difference in fat content was observed. In the thighs of females of Large gray geese fat content was higher than in the thighs of males of this breed by 0.29% (P&lt;0.05). At the same time, in females of the Large white breed, on the contrary, higher fat content than in males (by 0.27%) was observed in the chest muscles (P&lt;0.05). The chest muscles of both males and females of both breeds had more moisture and more crude protein than the thigh muscles. In contrast, the thigh muscles had a higher fat content (P&lt;0.05). As for protein, the muscles of the chest and thighs contained all the essential amino acids. However, the amino acid profile of male and female proteins of the same type in different muscle types, both within one breed and between breeds, differed slightly in the content of some amino acids, with the statistically reliable (P&lt;0.05) difference in some of them. Comparison of the amino acid profile of chest and thigh muscle proteins of both breeds of geese with the reference protein (FAO/WHO, 2013), showed that the muscle protein of geese of Large gray and Large white breeds contains a sufficient amount of all essential amino acids. The essential amino acid indices of the chest and thigh muscle proteins were similar for both breeds and were approximately 1.8-fold higher than the reference protein index. These data indicate the high nutritional value of meat of both goose breeds and the feasibility of their further use for meat production in Ukraine.

Avian mitochondria respiration is not predicated solely on complex abundance and DNA content

Skeletal muscle is a collection of heterogenous muscle fiber types differing in their ability to contract and metabolize energy substrates. The relative proportion of each fiber type in muscle drive function, where oxidative muscles are more fatigue resistant and generally have greater amounts of mitochondria than more glycolytic muscles that have less mitochondria because of their reliance on glycolytic reactions for energy production. However, even highly glycolytic muscles, like the breast muscle of chickens have mitochondria. Yet, differences in mitochondrial characteristics across muscle types remain largely unknown.We compared glycolytic and oxidative muscles of two different species in an attempt to understand better the relationship between mitochondrial DNA (mtDNA) and protein abundance, and mitochondria function. Glycolytic muscles longissimus lumborum (LL) and the pectoralis major (PM) and oxidative muscles masseter (MS) and quadriceps femoris (QF) were collected from adult pigs and chickens, respectively. Greater mtDNA abundance (2 -ΔΔCT ) was noted in oxidative muscles of both species compared to their glycolytic counterparts ( P &lt; 0.01). However, when absolute mtDNA was estimated, porcine MS had more mtDNA than LL ( P &lt; 0.001), whereas both avian muscles were equivalent. Porcine MS muscle had greater succinate dehydrogenase (SDHA, P &lt; 0.05) and citrate synthase (CS, P &lt; 0.001) than LL, while avian QF muscle had greater CS ( P &lt; 0.001) and voltage dependent anion channel (VDAC, P &lt; 0.05) compared to PM muscle. Isolated mitochondria from the MS of pigs had more electron transport chain complex I (CI, P &lt; 0.010) and complex II (CII, P &lt; 0.05) than those isolated from the LL. Avian mitochondria had no differences in either electron transport chain complexes across muscle, but mitochondria from the PM had greater VDAC than those purified from the QF. Oxygen consumption rates (OCR) followed muscle type, where mitochondria from oxidative muscles consumed more oxygen than those of glycolytic muscle when stimulated with ADP ( P &lt; 0.05). These data show that porcine mtDNA abundance, mitochondrial protein abundance, and mitochondrial function is greater in oxidative muscle compared to glycolytic muscle, and that respiration is greater in mitochondria from more oxidative muscle. However, differences in the relative abundance of mtDNA and electron transport chain complexes were not evident in isolated mitochondria from the chicken, yet respired differently nonetheless suggesting mtDNA and protein may not be directly correlated to the overall function of mitochondria. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Mechanosensory encoding in ex vivo muscle-nerve preparations.

Our objective was to evaluate an ex vivo muscle-nerve preparation used to study mechanosensory signalling by low threshold mechanosensory receptors (LTMRs). Specifically, we aimed to assess how well the ex vivo preparation represents in vivo firing behaviours of the three major LTMR subtypes of muscle primary sensory afferents, namely type Ia and II muscle spindle (MS) afferents and type Ib tendon organ afferents. Using published procedures for ex vivo study of LTMRs in mouse hindlimb muscles, we replicated earlier reports on afferent firing in response to conventional stretch paradigms applied to non-contracting, that is passive, muscle. Relative to in vivo studies, stretch-evoked firing for confirmed MS afferents in the ex vivo preparation was markedly reduced in firing rate and deficient in encoding dynamic features of muscle stretch. These deficiencies precluded conventional means of discriminating type Ia and II afferents. Muscle afferents, including confirmed Ib afferents were often indistinguishable based on their similar firing responses to the same physiologically relevant stretch paradigms. These observations raise uncertainty about conclusions drawn from earlier ex vivo studies that either attribute findings to specific afferent types or suggest an absence of treatment effects on dynamic firing. However, we found that replacing the recording solution with bicarbonate buffer resulted in afferent firing rates and profiles more like those seen in vivo. Improving representation of the distinctive sensory encoding properties in ex vivo muscle-nerve preparations will promote accuracy in assigning molecular markers and mechanisms to heterogeneous types of muscle mechanosensory neurons.

John Squire and the myosin thick filament structure in muscle.

The structure of the thin, actin-containing filament of muscle is both highly conserved across a broad range of muscle types and is now well understood. The structure of the thick, myosin-containing filaments of striated muscle are quite variable and remained comparatively unknown until recently, particularly in the arrangement of the myosin tails. John Squire played a major role not only in our understanding of thin filament structure and function but also in the structure of the thick filaments. Long before much was known about the structure and composition of muscle thick filaments, he proposed a general model for how myosin filaments were constructed. His role in our current understanding the structure of striated muscle thick filaments and the extent through which his predictions have held true is the topic of this review.

Real-World Clinical Utilization Differences of onabotulinumtoxinA and abobotulinumtoxinA in Upper Limb Spasticity (P12-8.013)

<h3>Objective:</h3> To compare real-world clinical utilization of onabotulinumtoxinA (onabotA) and abobotulinumtoxinA (abobotA) in the treatment of adult upper limb spasticity (ULS). <h3>Background:</h3> 3 botulinum toxin type A (BoNT/A) products are approved by the US Food and Drug Administration (FDA) to treat ULS. Each BoNT/A product is manufactured and tested via proprietary processes, resulting in unique clinical profiles. FDA-mandated boxed warnings state that potency units of one product are not interchangeable and cannot be converted into units of another BoNT/A product. We compared real-world clinical utilization of onabotA and abobotA in the treatment of adult ULS. <h3>Design/Methods:</h3> De-identified medical records were obtained via survey of 101 unique healthcare professionals on patients diagnosed with ULS per International Classification of Diseases, 10th revision, (ICD-10) and treated via botulinum toxin using current procedural terminology (CPT) in the US. 215 patient charts were reviewed: 107 treated with onabotA and 108 with abobotA. Patients received at least 3 treatments of onabotA or abobotA in 1 spastic upper limb prior to March 2020. Number and type of muscles injected were compared between BoNT/A products. <h3>Results:</h3> 75% of patients were classified as having moderate-to-severe ULS by the injector. On average, patients were diagnosed with ULS for &gt;3 years: onabotA 44.2 months (10–200) or abobotA 40.0 months (11–212). A significantly greater average number of muscles were injected with onabotA (4.3; range, 1 to 16), compared with abobotA (3.1; range, 1 to 8), <i>P</i>=0.0001. Significantly more patients received onabotA injections in forearm muscles (87/107, 81.3%) compared with abobotA (70/108, 64.8%), <i>P</i>=0.0064. Similarly, a significant difference was observed in the utilization of onabotA in hand muscles (23/107, 21.5%) compared with abobotA (4/108, 3.7%), <i>P</i>=0.0001. <h3>Conclusions:</h3> These results are consistent with published evidence across other indications, further supporting that each BoNT/A product is unique and not interchangeable as indicated by the FDA. <b>Disclosure:</b> Dr. Nelson has received personal compensation for serving as an employee of Allergan, an AbbVie company. Dr. Nelson has received stock or an ownership interest from Allergan, an AbbVie company. Dr. Zuzek has received personal compensation for serving as an employee of AbbVie Inc.. Dr. Zuzek has stock in AbbVie Inc.. Marc Schwartz has nothing to disclose. Dr. Singh has received personal compensation for serving as an employee of AbbVie. Dr. Singh has stock in AbbVie.

Progress in Bioengineering of Myotropic Adeno-Associated Viral Gene Therapy Vectors

The ability to specifically, safely, and efficiently transfer therapeutic payloads to the striated musculature via a minimally invasive delivery route remains one of the most important but also most ambitious aims in human gene therapy. Over the past two decades, a flurry of groups have harnessed recombinant adeno-associated viruses (AAVs) for this purpose, carrying cargoes that were packaged either in one of the various wild-type capsids or in a synthetic protein shell derived by molecular bioengineering. In this study, we provide an overview over the most commonly used techniques for the enrichment of muscle-specific (myotropic) AAV capsids, typically starting off with the genetic diversification of one or more extant wild-type sequences, followed by the stratification of the ensuing capsid libraries in different muscle types in small or large animals. These techniques include the shuffling of multiple parental capsid genes, peptide display in exposed capsid loops, mutagenesis of individual capsid residues, creation of chimeras between two viral parents, or combinations thereof. Moreover, we highlight alternative experimental or bioinformatic strategies such as ancestral reconstruction or rational design, all of which have already been employed successfully to derive synthetic AAV capsids or vectors with unprecedented in vivo efficiency and/or specificity in the musculature. Most recently, these efforts have culminated in the isolation of unique clades of myotropic vectors called AAVMYO or MyoAAV that have in common the display of the amino acid motif RGD (arginine-glycine-aspartate) on the capsid surface and that exhibit the highest transduction rate in striated muscles of mice or nonhuman primates reported to date. Finally, we note essential looming improvements that will facilitate and accelerate clinical translation of these latest generations of myotropic AAVs, including the identification and utilization of capsid selection or validation schemes that promise optimal translation in humans, and continued efforts to enhance patient safety by minimizing hepatic off-targeting.

A mammal and bird's-eye-view of the pupil during sleep and wakefulness.

Besides regulating the amount of light that reaches the retina, fluctuations in pupil size also occur in isoluminant conditions during accommodation, during movement and in relation to cognitive workload, attention and emotion. Recent studies in mammals and birds revealed that the pupils are also highly dynamic in the dark during sleep. However, despite exhibiting similar sleep states (rapid eye movement [REM] and non-REM [NREM] sleep), wake and sleep state-dependent changes in pupil size are opposite between mammals and birds, due in part to differences in the type (striated vs. smooth) and control of the iris muscles. Given the link between pupil dynamics and cognitive processes occurring during wakefulness, sleep-related changes in pupil size might indicate when related processes are occurring during sleep. Moreover, the divergent pupillary behaviour observed between mammals and birds raises the possibility that changes in pupil size in birds are a readout of processes not reflected in the mammalian pupil.

Nanomaterial-Based Scaffolds for Tissue Engineering Applications: A Review on Graphene, Carbon Nanotubes and Nanocellulose.

Nanoscale biomaterials have garnered immense interest in the scientific community in the recent decade. This review specifically focuses on the application of three nanomaterials, i.e., graphene and its derivatives (graphene oxide, reduced graphene oxide), carbon nanotubes (CNTs) and nanocellulose (cellulose nanocrystals or CNCs and cellulose nanofibers or CNFs), in regenerating different types of tissues, including skin, cartilage, nerve, muscle and bone. Their excellent inherent (and tunable) physical, chemical, mechanical, electrical, thermal and optical properties make them suitable for a wide range of biomedical applications, including but not limited to diagnostics, therapeutics, biosensing, bioimaging, drug and gene delivery, tissue engineering and regenerative medicine. A state-of-the-art literature review of composite tissue scaffolds fabricated using these nanomaterials is provided, including the unique physicochemical properties and mechanisms that induce cell adhesion, growth, and differentiation into specific tissues. In addition, in vitro and in vivo cytotoxic effects and biodegradation behavior of these nanomaterials are presented. We also discuss challenges and gaps that still exist and need to be addressed in future research before clinical translation of these promising nanomaterials can be realized in a safe, efficacious, and economical manner.

Research and development of artificial muscles made of nylon fishing line for robots based on lever mechanisms

Subject of research: two types of artificial muscles made by secondary spiralization from nylon fishing line with cross-sectional diameters of 1.2 millimeters and 0.5 millimeters, which can be used in the manufacture of robots based on lever mechanisms, as well as in other mechanisms and systems as propellers.&#x0D; Purpose of research: to highlight the advantages and disadvantages of each type of artificial muscles obtained by secondary spiralization from nylon fishing line of different diameters.&#x0D; Methods and objects of research: the article analyzed the method of manufacturing an artificial muscle. A method of measuring the maximum possible lifting weight of the load has been experimentally found. The operating temperature conditions for an artificial muscle made of nylon fishing line and sufficient weights of loads for the successful functioning of an artificial muscle made of nylon fishing line of various cross-sectional diameters were selected by an experimental method.&#x0D; Results of research: the results of tensile tests were carried out and analyzed. The numerical difference of the lifted weight relative to the proper mass of the spiral is calculated.

염소와 양 골격근의 근섬유 특성

This study aimed to provide a fundamental summary of the caprine and ovine muscle fiber characteristics. The goat and sheep industries have been experiencing growth due to their adaptability to market changes and the diversity of their products. Muscle fibers, which represent the basic unit of muscle and an essential factor in assessing meat quality, can be classified into several types by their contractile and metabolic properties. Species, breeds, muscle type, age, and sex are the main factors affecting muscle fiber characteristics. While the effects of these factors on muscle fiber characteristics of major livestock species (cattle, pigs, and chickens) are widely studied, goats and sheep (the main meat sources among minor livestock species) have not fully studied. Understanding muscle fiber characteristics will help to development technologies for regulating goat and lamb meat quality. In the present study, the muscle fiber characteristics of the caprine and ovine skeletal muscles assessed in previous studies were summarized. In addition, the effects of breed, sex, age, and muscle type on the caprine and ovine muscle fiber characteristics were assessed using the results of previous studies. Specific in-depth studies on muscle fiber characteristics and their relationship to the quality characteristics of goat and lamb meat are required. These studies will help to extend shelf-life and retard deterioration in meat quality during storage or freeze-thawing of goat and lamb meat.