Muscle Structure Research Articles

Orthopedic Manifestations of Spinal Muscular Atrophy: Clarified and Unresolved Theoretical and Practical Issues

Summary. Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by progressive weakness and muscle atrophy resulting from degeneration of neurons in the spinal and bulbar parts of the brain. Objective. This study aims to analyze the literature devoted to the diagnosis and treatment of orthopedic pathologies in patients with various forms of SMA. Materials and Methods. The study is based on a retrospective review of articles focused on the diagnosis and treatment of patients with SMA. The PubMed database was searched for articles published between 2010 and 2024, with a focus on materials from the last five years. Results and Discussion. The literature search on musculoskeletal pathologies in SMA revealed a limited number of studies addressing the clinical and orthopedic manifestations of SMA and their dependence on the type of disease. There is practically no information on changes in the structural and functional state of bone tissue and muscle structures in patients with SMA. No unified classification has been found that defines the impairment of the functional state of the lower extremities depending on the muscle strength deficit, the type of orthopedic manifestations, and the degree of loss of function affecting independent movement. The analysis of the literature indicates a lack of consensus regarding surgical strategies for the treatment of orthopedic manifestations of SMA; the features of surgical interventions for the correction of certain orthopedic manifestations are also not covered, and a system for medical correction of disorders in the structural state of the bone system in SMA has not been developed. Conclusions. The pathology of the musculoskeletal system in SMA requires a detailed fundamental study considering the type of disease, its progression, the condition of muscle and bone structures, patient age, the type and severity of orthopedic pathology, while the methods used for its correction require further development and improvement.

Comparison of gait and architecture of the medial gastrocnemius in developmentally delayed children with different muscle tone: A preliminary pilot study.

Muscle tone alteration reduces gait and motor function in children with developmental delays. We aimed to determine differences in gait and structure of the medial gastrocnemius muscle between typically developing children and children with developmental delays with different muscle tone. Forty-nine participants were divided into typically developing children (n=22), children with spastic hemiplegia (n=6), children with spastic diplegia (n=9), and children with central hypotonia (n=12). A wearable gait analysis system was used to measure spatiotemporal variables and pelvic movement, and ultrasonography was used to measure the pennation angle, thickness, and fascicle length of the medial gastrocnemius. Children with spastic hemiplegia had significantly smaller total symmetric index and pelvic tilt symmetric index than typically developing children (P<0.050). Children with spastic diplegia had smaller pennation angle than typically developing children (P<0.050), and children with central hypotonia had lower velocity than typically developing children (P<0.050). Children with spastic diplegia had a greater pelvic rotation range than children with central hypotonia (P<0.050). This study helps to understand gait and muscle structure in central hypotonia and spastic cerebral palsy.

Differential transcriptomic profiling of lipid metabolism and collagen remodeling in fast- and slow-twitch skeletal muscles in aging.

Skeletal muscle function gradually declines with aging, presenting substantial health and societal challenges. Comparative analysis of how aging affects fast- and slow-twitch muscles remains lacking. We utilized 20-month-old mice to reveal the aging effects on muscle structure and fiber composition, followed by bulk RNA sequencing for fast- and slow-twitch muscles and integration with human single-cell RNA sequencing dataset providing a comparative analysis across species. In mouse slow-twitch muscles, aging induced a switch from fast to slow fibers and distinctively altered lipid metabolism in ceramide and triglyceride, with the upregulation of regulatory genes Gk and Ppargc1a also observed in human slow fibers. Additionally, both types of muscles exhibited common collagen deposition and fibrosis, possibly due to the imbalance between collagen synthesis and degradation. The extracellular matrix gene changes substantially overlapped between mice and humans in aging, yet also highlighted clear differences. This integrative analysis provides further understanding of aged fast- and slow-twitch muscles and offers new insights into the molecular changes in aging.

МОРФОФУНКЦИОНАЛЬНЫЕ И БИОЭЛЕКТРИЧЕСКИЕ ХАРАКТЕРИСТИКИ НЕКОТОРЫХ МЫШЦ ЗАПЯСТНОГО СУСТАВА У СОБАКИ: ПИЛОТНОЕ ИССЛЕДОВАНИЕ

The paper presents the morphofunctional characteristics of some muscles of the dog's wrist joint, as well as their bioelectrical characteristics. The purpose of the study is to describe the bioelectrical characteristics of the radial and ulnar extensor carpi of the dog, taking into account the morphofunctional characteristics of these muscles. Objectives of the study: to conduct a morphological and electrophysiological study of the radial and ulnar extensor wrist muscles in dogs; identify patterns of EMG formation depending on the internal structure and innervation of muscles, and conduct a comparative assessment of the morphological and bioelectrical characteristics of the muscles being studied. Research was carried out at the Department of Anatomy, Histology, Physiology and Pathological Anatomy of the Omsk State Agrarian University named after P.A. Stolypin (Omsk). As a result of the studies, it was revealed that the innervation of the muscle fibers of the dog’s extensor carpi ulnaris and radialis has a similar, group character, that is, groups of muscle fibers have a large number of motor units. These groups are reflected on the EMG as separate complexes. An individual set of action potentials in the EMG signal pattern has duration of 0.01–0.014 s and a frequency of 600–800 Hz. The length of the muscle bundles inboth muscles is different: for the extensor carpi ulnaris it is 0.5 cm, for the radial one, respectively, 3.5 cm. Thus, it was found that the characteristics of the innervation and internal structure of the muscle affect the pattern of the EMG signal. The influence of muscle structure by the type of feathering and the length of muscle fibers (in feathery muscles) was not revealed. Thus, the resulting pattern (pattern) of the EMG signal is characteristic of statodynamic muscles. The proposed model of EMG signal formation, as a result of further development, will have the prospect of being used for qualitative and quantitative interpretation and assessment of the functional state of the neuromuscular system in animals and humans.

GsMTx-4 combined with exercise improves skeletal muscle structure and motor function in rats with spinal cord injury.

Motor dysfunction and muscle atrophy are typical symptoms of patients with spinal cord injury (SCI). Exercise training is a conventional physical therapy after SCI, but exercise intervention alone may have limited efficacy in reducing secondary injury and promoting nerve regeneration and functional remodeling. Our previous research found that intramedullary pressure after SCI is one of the key factors affecting functional prognosis. It has been reported that GsMTx-4, a specific blocker of the mechanosensitive ion channels Piezo1, can protect the integrity of the neuromuscular junction and promote nerve regeneration, and thus has the potential as a therapeutic agent for SCI. In this study, we observed the combined and separate therapeutic effect of GsMTx-4 and exercise on the structure of the soleus muscle and motor function in rats with SCI. At 42 days post-injury, compared with SCI rats, the Basso-Beattie-Bresnahan score (P = 0.0007) and Gait Symmetry (P = 0.0002) were significantly improved after combination therapy. On histology of rat soleus muscle, compared with SCI rats, the combined treatment significantly increased the wet weight ratio, muscle fiber cross-sectional area and acetylcholinesterase (all P<0.0001). On histology of rat spinal tissue, compared with SCI rats, the combined treatment significantly increased neuron counts and BDNF levels, and significantly reduced the percentage of TUNEL-positive cells (all P<0.0001). On physiology of rat soleus muscle, compared with SCI rats, the combined treatment increased the succinate dehydrogenase expression (P<0.0001), while the expression of α-glycerophosphate dehydrogenase (P<0.0001) and GDF8 protein (P = 0.0008) decreased. Results indicate the combination therapy effectively improves histopathology of spinal cord and soleus muscle in SCI rats, enhancing motor function. This study was conducted on animal models, it offers insights for SCI treatment, advancing understanding of lower limb muscle pathology post-SCI. Further research is needed for clinical validation in the future.

Treatment of Denervated Muscle Atrophy by Injectable Dual-Responsive Hydrogels Loaded with Extracellular Vesicles.

Denervated muscle atrophy, a common outcome of nerve injury, often results in irreversible fibrosis due to the limited effectiveness of current therapeutic interventions. While extracellular vesicles (EVs) offer promise for treating muscle atrophy, their therapeutic potential is hindered by challenges in delivery and bioactivity within the complex microenvironment of the injury site. To address this issue, an injectable hydrogel is developed that is responsive to both ultrasound and pH, with inherent anti-inflammatory and antioxidant properties, designed to improve the targeted delivery of stem cell-derived EVs. This hydrogel system allows for controlled release of EVs from human umbilical cord mesenchymal stem cells (HUC-MSCs), adapting to the specific conditions of the injury environment. In vivo studies using a rat model of nerve injury demonstrated that the EV-loaded hydrogel (EVs@UR-gel) significantly preserved muscle function. Six weeks post-nerve reconstruction, treated rats exhibited muscle strength, circumference, and wet weight reaching 89.53 ± 0.96%, 76.02 ± 7.49%, and 88.0 ± 2.65% of healthy controls, respectively, alongside an improvement in the sciatic nerve index (-0.11±0.09). This platform presents a novel therapeutic approach by maintaining EV bioactivity, enabling tunable release based on the disease state, and facilitating the restoration of muscle structure and function.

Effects of Aging on Intramuscular Collagen-Related Factors After Injury to Mouse Tibialis Anterior Muscle.

Collagen I is the most abundant type of intramuscular collagen. Lysyl oxidase promotes collagen cross-link formation, which helps stabilize the extracellular matrix. Furthermore, matrix metalloproteinases, responsible for collagen degradation, maintain typical muscle structure and function through remodeling. Although it is well known that aging leads to delayed recovery of muscle fibers, the impact of aging on the remodeling of intramuscular collagen is not well understood. In this study, we investigated the impact of aging on collagen remodeling during muscle injury recovery using young and old mouse models. Muscle injury was induced in the right tibialis anterior (TA) muscle of male C57BL/6J mice [aged 21 weeks (young) and 92 weeks (old)] using intramuscular cardiotoxin injection, with the left TA serving as a sham with saline injection. Following a one-week recovery period, aging was found to delay the recovery of the fiber cross-sectional area. The intensity and area of immunoreactivity for collagen I were significantly increased in old mice compared to young mice post-injury. Additionally, Lox expression and the number of LOX (+) cells in the extracellular matrix significantly increased in old mice compared to young mice post-injury. Furthermore, Mmp9 and MMP9 expression levels after muscle injury were higher in old mice than in young mice. These results suggest that muscle injury in old mice can lead to increased collagen I accumulation, enhanced collagen cross-link formation, and elevated MMP9 expression compared to young mice.

Effect of Liquid Nitrogen Freezing on Maintaining the Quality of Crayfish During Freeze-Thaw Cycles: Muscle Structure and Myofibrillar Proteins Properties.

The quality of frozen crayfish (Procambarus clarkii) is challenged by freeze-thaw (FT) cycles during storage. The effect of freezing methods on the quality of crayfish during FT cycles was investigated by comparing physicochemical properties, microstructure, and myofibrillar protein (MPs) properties. Three methods were used for crayfish freezing, including air convective freezing (AF) at -20 °C and -50 °C, as well as liquid nitrogen freezing (LNF) at -80 °C. The frozen crayfish were thawed at 4 °C after 45 d of frozen storage as 1 FT cycle. After 5 FT cycles, the water holding capacity of LNF crayfish (70.8%) was significantly (p < 0.05) higher than that of -20 °C AF crayfish (60.6%) and -50 °C AF crayfish (63.5%). The drip loss of LNF crayfish (7.83%) was significantly lower than that of AF crayfish. Moreover, LNF maintained the gel strength and the thermal stability of MPs from crayfish with higher gel storage modulus and enthalpy. These results demonstrated that LNF minimized the formation of large ice crystals, preserving the structural integrity of muscle and the properties of MPs, thereby maintaining crayfish quality. This study investigated the effect of LNF in preserving crayfish quality during FT cycles, providing valuable insights for reducing the quality degradation of aquatic products during storage and transportation.

Woxuanzhongzhou formula improves DHEAS and high-fat diet-induced IR and anovulatory mice via AMPK/PGC1- α/Irisin pathway

BackgroundPolycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women of reproductive age. Anovulation is one of the most important clinical features of PCOS, and insulin resistance (IR) is one of the critical pathogenic factors. Woxuanzhongzhou (WXZZ) is a traditional herbal formulation that has shown efficacy in treating PCOS combined with IR, but the underlying mechanism is not clear. The aim of this study was to investigate the molecular mechanism of WXZZ on dehydroepiandrosterone sulfate and high fat diet induced PCOS with IR mice.Methods40 female C57BL/6 mice were randomized to 4 groups: control group, model group, metformin group, and WXZZ group. Some mice is induced by dehydroepiandrosterone sulfate (DHEA) and high-fat diet (HFD) for 3 weeks. Following model induction, metformin and WXZZ were administered by gavage. Body weight, fasting blood glucose (FBG), fasting insulin (FINS) levels, the homeostatic model assessment of insulin resistance (HOMA-IR), and gonadal hormones were measured. Estrous cycles were monitored. The structure of the gastrocnemius muscle and subcutaneous fatty tissue were also evaluated. Additionally, serum irisin and non-esterified fatty acids (NEAF) levels and the protein and gene expression levels of AMPK, PGC1-α, FNDC5, irisin in the gastrocnemius muscle and CaMKK, AMPK, PGC1-α, UCP1 in fat were analyzed.ResultsThe DHEA + HFD + WXZZ group exhibited significant improvements in several key parameters compared to the DHEA + HFD group. WXZZ ameliorated endocrine and metabolic disorders, resumed estrous cycle in DHEAS and high-fat diet-induced IR and anovulatory mice. Significant reductions were observed in body weight, serum testosterone, luteinizing hormone, luteinizing hormone/ follicle-stimulating hormone ratio, FINS, and HOMA-IR. Additionally, WXZZ promoted irisin expression and secretion by up-regulating the protein and gene AMPK/PGC1-α/FNDC5 expression in gastrocnemius muscle and up-regulated the protein and gene CaMKK/AMPK/PGC1-α/UCP1 expression in fat. WXZZ inhibited the overproduction of serum NEFA, and reduced lipid accumulation. Structural analysis of the gastrocnemius muscle and adipose tissue revealed partial restoration.ConclusionWXZZ exhibits therapeutic effects in DHEAS and high-fat diet-induced IR and anovulatory mice. These effects may be mediated through the activation of AMPK/PGC1-α pathway in muscle to promote the secretion of irisin.

In situ structural-functional synchronous dissection of dynamic neuromuscular system via an integrated multimodal wearable patch.

Neuromuscular abnormality is the leading cause of disability in adults. Understanding the complex interplay between muscle structure and function is crucial for effective treatment and rehabilitation. However, the substantial deformation of muscles during movement (up to 40%) poses challenges for accurate assessment. To address this, we developed a wearable structural-functional sensing patch (WSFP) that enables synchronous analysis of muscle structure and function. The WSFP incorporates a soft, stretchable electrode array for high-performance electrophysiological monitoring with low contact impedance and high stability. Its innovative design absorbs skin deformation stress, ensuring stable adhesion of a flexible ultrasound transducer array, offering higher-fidelity imaging. With dynamic tissue imaging, it allows real-time visualization of muscle structure. The WSFP achieves superior accuracy in dynamic action recognition and disease assessment compared to single-modal methods, maintaining stable operation during motion for up to 72 hours. This study advances neuromuscular system analysis and improves diagnostic precision.

Leech-Inspired Amphibious Soft Robot Driven by High-Voltage Triboelectricity.

Leech locomotion, characterized by alternating sucker attachment and body contraction provideshigh adaptability and stability on complex terrains. Herein, a leech-inspired triboelectric soft robot is proposed for the first time, capable of amphibious movement, climbing, and load-carrying crawling. A high-performance triboelectric bionic robot system is developed to drive and control electro-responsive soft robots. Its core components include: i) a leech-inspired soft robot (LSR) made from segmented dielectric elastomer muscles. ii) The triboelectric sucker produces anisotropic frictional forces. iii) The multi-channel high-voltageoutput triboelectric nanogenerator (HDC-TENG) effectively drives the LSR. iv) The high-voltage triboelectric control unit adapted for the HDC-TENG enables flexible LSR control. Using the scalable structure of the dielectric elastomer muscles enables the LSR to achievea maximum crawling speed of 0.39 body lengths per minute on land (45 mm min-1) and 0.22 body lengths per minute in liquid (30.5 mm min-1). It can also carry a payload of 11.55 grams on acrylic while crawling. This research provides a sustainable and promising new solution for self-powered high-voltage energy sources suitable for electro-responsive soft robots.

Functional control of myosin motors in the cardiac cycle.

Contraction of the heart is driven by cyclical interactions between myosin and actin filaments powered by ATP hydrolysis. The modular structure of heart muscle and the organ-level synchrony of the heartbeat ensure tight reciprocal coupling between this myosin ATPase cycle and the macroscopic cardiac cycle. The myosin motors respond to the cyclical activation of the actin and myosin filaments to drive the pressure changes that control the inflow and outflow valves of the heart chambers. Opening and closing of the valves in turn switches the myosin motors between roughly isometric and roughly isotonic contraction modes. Peak filament stress in the heart is much smaller than in fully activated skeletal muscle, although the myosin filaments in the two muscle types have the same number of myosin motors. Calculations indicate that only ~5% of the myosin motors in the heart are needed to generate peak systolic pressure, although many more motors are needed to drive ejection. Tight regulation of the number of active motors is essential for the efficient functioning of the healthy heart - this control is commonly disrupted by gene variants associated with inherited heart disease, and its restoration might be a useful end point in the development of novel therapies.

Protective impact of melatonin on paclitaxel induced damage on skeletal muscle fibers in albino rats

Background Paclitaxel is a chemotherapy used for the treatment of solid cancers. Patients receiving paclitaxel report fatigue. Melatonin is anti-inflammatory, antioxidant, and antiapoptotic. It is safe for human. Aim To evaluate the histological impact of paclitaxel on the skeletal muscle of rats and the potential protective effects of melatonin. Materials and methods Thirty-five albino rats were categorized into four groups. Group I contained 10 rats that were used as the control group. Group II comprised 5 rats that were administered a daily oral suspension of melatonin at a dosage of 5 mg/kg for 2 months. Group III included 10 rats given paclitaxel through intraperitoneal injection at a dosage of 16 mg/kg, diluted in 1 ml of normal saline, once weekly for 5 consecutive weeks. Group IV contained 10 rats that received melatonin and paclitaxel concomitantly at the same doses and duration as mentioned in group II and group III. Skeletal muscle specimens were processed to be examined by the light microscope. Results The paclitaxel injected group showed alteration in the histological structure of skeletal muscle. There were wide spaces between muscle bundles and between individual muscle fibers with an apparent increase in the connective tissue component of endomysium and perimysium. Congestion of the blood vessels and hemorrhage were observed. There was a discontinuation of muscle fibers and internalization of myonuclei. Most of the alternations were less pronounced in paclitaxel injected rats that received melatonin. Conclusion Melatonin could protect the skeletal muscle against changes induced by paclitaxel through its anti-inflammatory, antioxidant, and antiapoptotic effects.

Anatomy-based diffusion-weighted MRI quality metric: a proof-of-concept for deriving accurate muscle fiber orientation

Objective.Diffusion-weighted MRI (DW-MRI) is used to quantitatively characterize the microscopic structure of muscle through anisotropic water diffusion in soft tissue. Applications such as tumor propagation modeling require precise detection of muscle fiber orientation. That is, the direction along the fibers that coincides with the direction of the principal eigenvector of the diffusion tensor reconstructed from DW-MRI data. For clinical applications, the quality of image data is determined by the signal-to-noise ratio (SNR) that must be achieved within the appropriate scan time. The acquisition protocol must therefore be optimized. This implies the need for SNR criteria that match the data quality of the application.Approach.Muscles with known structural heterogeneity, e.g. bipennate muscles such as the rectus femoris in the thigh, provide a natural quality benchmark to determine accuracy of inferred fiber orientation at different scan parameters. In this study, we analyze DW-MR images of the thigh of a healthy volunteer at different SNRs and use PCA to identify subsets of voxels with different directions of diffusion tensor eigenvectors corresponding to different pennate angles. We propose to use the separation index of spatial co-localization of the clustered eigenvectors as a quality metric for fiber orientation detection.Main results.The clustering in the PCA component coordinates can be translated to the separation of the two compartments of the bipennate muscle on either side of the central tendon according to the pennate angle. The separation index reflects the degree of the separation and is a function of SNR.Significance.Because the separation index allows joint estimation of spatial and directional noise in DW-MRI as a single parameter, it will allow future quantitative optimization of DW-MRI soft tissue protocols.

Melatonin Ameliorates Organellar Calcium Homeostasis, Improving Endoplasmic Reticulum Stress-Mediated Apoptosis in the Vastus Lateralis Muscle of Both Sexes of Obese Diabetic Rats.

Endoplasmic reticulum (ER) stress is a crucial factor in the progression of obesity-related type 2 diabetes (diabesity), contributing to skeletal muscle (SKM) dysfunction, calcium imbalance, metabolic inflexibility, and muscle atrophy. The ER and mitochondria together regulate intracellular calcium levels, and melatonin, a natural compound with antioxidant properties, may alleviate these challenges. Our previous research showed that melatonin raises intracellular calcium and preserves muscle structure by enhancing mitochondrial function in obese diabetic rats. This study further explores melatonin's potential to reduce ER stress in the vastus lateralis (VL) muscle by modulating the unfolded protein response (UPR) and restoring calcium levels disrupted by diabesity. Five-week-old Zücker diabetic fatty (ZDF) rats and lean littermates of both sexes were divided into control and melatonin-treated groups (10 mg/kg/day for 12 weeks). Flame atomic absorption spectrometry results showed that melatonin restored VL intraorganellar calcium homeostasis, increasing calcium levels in mitochondria and reducing them in the ER by raising the activity and expression of calcium transporters in both sexes of ZDF rats. Melatonin also decreased ER stress markers (GRP78, ATF6, IRE1α, and PERK) and reduced pro-apoptosis markers (Bax, Bak, P-JNK, cleaved caspase 3 and 9) while increasing Bcl2 levels and melatonin receptor 2 (MT2) expression. These findings suggest that melatonin may protect against muscle atrophy in obese and diabetic conditions by mitigating ER stress and calcium imbalance, highlighting its therapeutic potential.

Limiting serine availability during tumor progression promotes muscle wasting in cancer cachexia

Cancer cachexia is a multifactorial syndrome characterized by a progressive loss of body weight occurring in about 80% of cancer patients, frequently representing the leading cause of death. Dietary intervention is emerging as a promising therapeutic strategy to counteract cancer-induced wasting. Serine is the second most-consumed amino acid (AA) by cancer cells and has emerged to be strictly necessary to preserve skeletal muscle structure and functionality. Here, we demonstrate that decreased serine availability during tumor progression promotes myotubes diameter reduction in vitro and induces muscle wasting in in vivo mice models. By investigating the metabolic crosstalk between colorectal cancer cells and muscle cells, we found that incubating myotubes with conditioned media from tumor cells relying on exogenous serine consumption triggers pronounced myotubes diameter reduction. Accordingly, culturing myotubes in a serine-free medium induces fibers width reduction and suppresses the activation of the AKT-mTORC1 pathway with consequent impairment in protein synthesis, increased protein degradation, and enhanced expression of the muscle atrophy-related genes Atrogin1 and MuRF1. In addition, serine-starved conditions affect myoblast differentiation and mitochondrial oxidative metabolism, finally inducing oxidative stress in myotubes. Consistently, serine dietary deprivation strongly strengthens cancer-associated weight loss and muscle atrophy in mice models. These findings uncover serine consumption by tumor cells as a previously undisclosed driver in cancer cachexia, opening new routes for possible therapeutic approaches.

Comparison of microbial and chemical changes in common carp (Cyprinus carpio) fillets reared in earthen basins, river cages and river fish during storage in refrigerator

The factors that greatly affect the quality of fish meat are type of nutrition and nutritional conditions, their effects are found in the muscle structure and stability of fish meat during the storage period. To conduct this study, fish were stored for 14 days at a temperature of 4 °C. During the refrigerated storage period of fish fillets, the approximate composition of fish fillets (moisture, protein, fat and ash) was measured, and the quality factors of fish were recorded. The results also showed that the highest amount of moisture and the lowest amount of fat were in fish cultured in earthen ponds, and the amount of protein did not change significantly between the different treatments, the amounts of TBA, FFA and TVN increased during the refrigerated storage period, and the pH changes were not regular between the different treatments. The highest amount of TBA and FFA was between the different treatments. It was also noted that the highest amount of moisture was in river fish. Comparison of the results of the different qualitative factors between the three treatments showed that treating fish in an earthen pond environment compared to the two treatments is more susceptible to spoilage during the refrigerated storage period. While the microbiological studies were conducted.

Temporomandibular joint and masticatory muscles morphometry and morphology in healthy subjects and individuals with temporomandibular dysfunction: An anatomical, radiological, and machine learning application study.

The study aimed to compare the morphometric and morphologic analyses of the bone structures of temporomandibular joint and masticatory muscles on Cone beam computed tomography (CBCT) in 62 healthy subjects and 33 subjects with temporomandibular dysfunction (TMDS) aged between 18 and 56 years. In addition, a machine learning (ML) pipeline involving the Random Forest classifier was used to automatically detect TMDS. Thirty parameters (including age and gender) associated with the condylar process, articular tubercle, mandibular fossa, ramus mandible, joint space, and masticatory muscles were examined using CBCT. Well-known steps including scaling, feature selection, and feature extension are used to build the ML pipeline. Among 30 parameters, angle between mediolateral axes of both the head of mandible, medial pterygoid muscle thickness (PMT), distance between the most superior point of head of the mandible and the mandibular fossa bone surface opposite, medial joint space, lateral joint space, articular tubercle inclination, mandibular fossa depth head of the mandible's length, and angle between the ramus mandible long axis and the coronal plane values showed significant differences between healthy subjects and TMDS. Additionally, from the above measurements, all parameters (except PMT) were significantly lower in TMDS than in healthy subjects. Moreover, the results show that it is possible to automatically detect temporomandibular dysfunction with an f1-score of 0.967 when arming our ML pipeline with feature selection and extension. The reference values of the condylar process, articular tubercle, mandibular fossa, ramus of mandible, and joint space may play a key role in increasing of the success of the surgical procedure, or the assessment/differentiating of the TMD. ML is capable of detecting TMD in an automatic and highly accurate way. Hence, it is also concluded that ML can be useful for cases requiring making automatic and highly correct predictions.

Comparative Analysis of Muscle Fibers in Selected Muscles of Working and Companion Dog Breeds.

The structural and functional characteristics of skeletal muscle fibers play a crucial role in understanding the physical capabilities of dogs, particularly in relation to their breed-specific roles. This study aimed to compare the muscle fiber composition of working and companion dog breeds by analyzing the triceps brachii and biceps femoris muscles, focusing on fiber morphology, myosin heavy chain (MYH) isoform distribution, and nuclei per fiber. A total of 12 dogs, divided equally into working and companion breed groups, were used in this study. Muscle samples were collected post-mortem and prepared for histological analysis using cryosectioning. Immunohistochemical staining was employed to identify the expression of MYH isoforms, including MYH2, MYH4, and MYH7, which correspond to type IIa, IIb, and type I fibers, respectively. The results demonstrated significant differences between the two breed groups. Working dogs exhibited larger muscle fibers, a higher proportion of type IIa (MYH2) and type I (MYH7) fibers, and a greater number of nuclei per fiber, suggesting adaptations for endurance and strength. In contrast, companion dogs showed a higher proportion of type IIb (MYH4) fibers, indicative of their capacity for short bursts of activity rather than sustained exertion. Companion breeds also displayed a higher fiber density but fewer nuclei per fiber, which may contribute to slower muscle regeneration. These findings may provide insights into the muscle adaptations of dogs based on their breed-specific functional demands and highlight the importance of considering these differences in veterinary care and rehabilitation. The study underscores the influence of selective breeding on muscle structure and function in dogs and suggests further research into breed-specific muscle recovery mechanisms.

Bullet Penetration In The Face Caused By Accidental Gunshot: A Case Report

Background: Clinical and radiological examinations are used to predict the location of the bullet in bullet penetration injury. The maxillofacial region had a variety of structure which could make the bullet deviate from its normal trajectories. Patient and Methods: A rare case of bullet penetration in the face caused by accidental gunshot is described. A 32 year-old male was hit by a bullet in the face with entrance wound on the left temporal region. Radiologic examination showed a bullet in the left inferior orbita. Treatment was exploration and extraction of the bullet. In this case we observe the difference between the clinical examination, radiological diagnosis and intraoperative findings Result: The patient underwent an explorative operation based on the prediction of location of the bullet from the clinical and radiological examination. The bullet was found in the inferior rectus muscle which the location is out of the prediction of clinical examination and radiologic findings. Summary: Clinical and radiological examination do not always give the accurate prediction regarding the location of bullet in penetrating bullet injury of the face because the face has a variety of bone, muscle and soft tissue structure.