Myogenic Diseases Research Articles

EMG phenomena of myogenic hyperexcitability

The type, distribution pattern and time course of spontaneous muscular activity are important for the diagnostics of neuromuscular diseases in the clinical practice. In neurogenic lesions with motor axonal involvement, pathologic spontaneous activity (PSA) is usually reliably detectable by needle electromyography (EMG) 2-4weeks after occurrence of the lesion. The distribution pattern correlates with the lesion location. The focus of the present work is the description of the different forms of PSA in myogenic diseases.

Wearable Electronics for Surface and Needle Electromyography Measurements

Because the electromyography (EMG) signal can reflect the potential of muscle contraction controlled by neural activities, it has aroused great interest from researchers. As a result, a number of studies have been conducted around EMG. EMG-based wearable electronics are used not only in the diagnosis of neurogenic or myogenic diseases but also in sports science, rehabilitation, augmented reality, and virtual reality. This article briefly introduces the development history and background of EMG technology, then focuses on the classification of EMG and its technical mechanisms and reviews representative EMG-based wearable electronics. Finally, the challenges and development trends of EMG-based wearable electronics are also discussed. Developing devices with high specificity, adaptability, and robustness remains challenging. It has become a trend to optimize EMG signals' classification, characterization and noise cancellation algorithms for future study by combining multiple technical means. Because of the various applications of wearable electronic devices based on EMG measurements, it will have promising prospects in many fields.

Plectin regulates Wnt signaling mediated-skeletal muscle development by interacting with Dishevelled-2 and antagonizing autophagy.

Skeletal muscle is the most abundant tissue in the human and animal body, loss of its function can lead to muscle aging and various myogenic diseases. The skeletal muscle development is a complex and tightly regulated process, which is driven by a variety of many factors, signaling pathways and regulatory mechanisms. Plectin (Plec), a cytolinker protein, is ubiquitously expressed in various tissues such as skin, muscle, plasma membrane, and most types of cells. Although known isoforms of Plec is well-characterized in muscle dystrophy, very little is known on the function of Plec in the skeletal muscle development. Here, we found that Plec plays a vital role in promoting C2C12 myoblasts differentiation and proliferation, but inhibits their apoptosis. Also, Plec regulates the expression of atrophy-related genes (atrogin-1 and muRF-1) to rescue muscle atrophy. Furthermore, we have demonstrated that Plec binds to Dishevelled-2 (Dvl-2) and forms a protein complex, which is then activate the canonical Wnt signaling. We also observed that Plec resists ubiquitination by stabilizing Dvl-2 and reduces the level of LC3-labeled Dvl-2 and antagonizes the autophagy system. In conclusion, our findings suggest that Plec regulates canonical Wnt signaling mediated skeletal development by stabilizing Dvl-2 and downregulating the cellular autophagic degradation system.

Metabolic Disturbance in Patients with Muscular Dystrophy and Reflection of Altered Enzyme Activity in Dystrophic Muscle: One Critical View

Muscular dystrophies are inherited myogenic diseases and considered by progressive muscle wasting and weakness with variable distribution and severity. The essential characteristics of muscular dystrophies are selective involvement, significant wasting and weakness of muscles. The most common and frequent types of muscular dystrophies are Duchenne Muscular Dystrophy (DMD), Becker Muscular Dystrophy (BMD), Facioscapulohumeral Dystrophy (FSHD) and Limb Girdle Muscular Dystrophy (LGMD). Metabolic disturbance is observed in muscular dystrophy patients (DMD, BMD, FSHD and LGMD-2B). Alteration in the level of metabolites (BCAA, Glu/ Gln, Ace, alanine, glucose, histidine, propionate, tyrosine and fumarate) in dystrophic muscle reflects the alteration in the activity of enzymes. Collectively, these observations propose that there is alteration in the rate of glycolysis, TCA cycle, fatty acid oxidation, gluconeogenesis pathway and protein metabolism (catabolism & anabolism) in the muscular dystrophy patients. Metabolic disturbance, further provide the explanation about the pathophysiology of muscular dystrophy.

Manufacturing autologous myoblast for regenerative medicine applications.

Autologous myoblasts have been tested in the treatment of muscle-related diseases. However, the standardization of manufacturing myoblasts is still not established. Here we report a flask and animal-free medium-based method of manufacturing clinical-grade myoblast together with establishing releasing criteria for myoblast products under Good Manufacturing Practice (GMP). Quadriceps muscle biopsy samples were donated from three patients with myogenic ptosis. After biopsy samples were digested through enzymatic dissociation, the cells were grown in T175 flasks (passage 0) and hyperflasks (passage 1) in the animal-free SkGMTM-2 skeletal muscle cell growth medium containing 5% human platelet lysate for 15-17 days. The harvested cells were released based on cell morphology, cell dose, viability, sterility, endotoxin, mycoplasma and immunophenotype. Myotube differentiation was also evaluated. 400 to 500 million myoblast cells were manufactured within 15 to 17 days by the end of passage 1, which met pre-determined releasing criteria. The manufactured myoblast cells could differentiate and fuse into myotubes in vitro, with the possible trend that the donor age may impact the differentiation ability of myoblasts. The present study establishes a flask-based method of manufacturing myoblast in the animal-free medium together with releasing criteria, which is simple, robust, inexpensive and easily reproducible. This study will serve as the validation for a planned phase 1 clinical trial to assess the use of autologous myoblast transplants for the treatment of myogenic ptosis and other myogenic diseases.

Neurogenic and Myogenic Diseases: Quantitative Texture Analysis of Muscle US Data for Differentiation.

Purpose To assess the multiple texture features of skeletal muscles in neurogenic and myogenic diseases by using ultrasonography (US). Materials and Methods After institutional review board approval, muscle US studies of the medial head of the gastrocnemius were performed prospectively in patients with neurogenic diseases (n = 25 [18 men]; mean age, 66.0 years ± 12.3 [standard deviation]), in patients with myogenic diseases (n = 21 [12 men]; mean age, 68.3 years ± 11.5), and in healthy control subjects (n = 21 [11 men]; mean age, 70.5 years ± 8.4) between January 2013 and May 2016. Written informed consent was obtained. Muscle texture parameters were obtained, and five algorithms were used to classify the groups. Results The neurogenic and myogenic disease groups showed higher echo intensities than the control subjects. The histogram-derived texture parameters had overlaps between the neurogenic and myogenic groups and thus had a low discrimination rate. With assessment of more classes of texture parameters, three groups were correctly classified (100% correct, according to four of five classification algorithms). Tenfold cross validation showed 93.5%-95.7% correct classification between the neurogenic and myogenic groups. The run-length matrix, autoregressive model, and co-occurrence matrix were particularly useful in distinguishing the neurogenic and myogenic groups. Conclusion Texture analysis of muscle US data can enable differentiation between neurogenic and myogenic diseases and is useful in noninvasively assessing underlying disease mechanisms. © RSNA, 2017 Online supplemental material is available for this article.

MicroRNA-133 inhibits cell proliferation, migration and invasion in prostate cancer cells by targeting the epidermal growth factor receptor

It has been shown that regulation of EGFR expression in prostate cancer cells is mostly at the transcriptional level. microRNA-133 (miR-133) has long been recognized as a muscle-specific miRNA which may regulate myoblast differentiation and participate in many myogenic diseases. Recently, it has been reported that miR-133 is also involved in other tumors, such as bladder cancer, esophageal cancer and may regulate cell motility in these cancer cells. In the present study, we examined the expression and effects of miR-133 in two hormone-insensitive prostate cancer cell lines. The expression of miR-133a and miR-133b were analyzed by quantitative RT-PCR. After transfection of miR-133a and miR-133b, cell viability assay, luciferase assay, western blot analysis, cell migration and invasion assay were conducted in Du145 and PC3 cells. In this study, we showed that miR‑133a and miR-133b are expressed at the detection limit in two hormone-insensitive prostate cancer cell lines, PC3 and DU145. Ectopic expression of miR-133 inhibited cell proliferation, migration and invasion in these cells. We also provide the first evidence that miR-133 may target EGFR. Our study provided the first glimpse of the functional role of miR-133 in two hormone-independent prostate cancer cell lines. These results may add to our knowledge on the molecular basis of prostate cancer progression.

Arthrogryposis multiplex congenita - a rare congenital stiff joints syndrome

Arthrogryposis multiplex congenita is not a disease but a term describing multiple congenital contractures. Etiological factors include neurological and primary myogenic diseases. This rare syndrome is present at birth and is characterized by reduced mobility of many joints. The contractures involve two or more joints with ankylosis. The accompanying musculature is hypoplastic, but multiple pterygia are also present. Arthrogryposis multiplex congenita is a heterogeneous group of disorders with the incidence rate of 6.2/100000 liveborn infants. The true incidence cannot be established, because many cases result in spontaneous miscarriages or stillbirth. More than 90% of cases are associated with birth defects. The cause of this syndrome is unknown. Many forms are not hereditary, though there are hereditary forms as well. This paper presents a case with arthrogryposis multiplex congenita. The pregnancy was not controlled regularly. During the pregnancy, oligohydramnion was detected. Due to contractures, labor ended is cesarean section. The child was born in the 34th week of gestation. Flexion and extension joint contractures were observed. Active and passive mobility of the afflicted joints was reduced. There was a limited motor function in the shoulder, elbow and wrist joints with a slight internal rotation of the shoulder joint and lower arm joints during pronation. The hips were subluxated; the feet were in equinovarus position and the fingers in ulnar deviation with partial syndactyly of the 4th and 5th fingers on the left hand. The infant had abnormal dermatoglyphics. The neck was short, and the 2nd and 3rd cervical vertebrae were fused. There was also a slight left-sided thoracic scoliosis. Trismus was present due to the existing ankylosis of the temporomandibular joint. The karyotype was normal. The serum creatinine phosphokinase was slightly elevated The electromyographic picture indicate non-specific signs of myopathy. This is a case report of a "stiff joint syndrome". Due to the fact that data from the family history were unavailable, we could not establish the type of syndrome. However, heredity, growth and development at later age, as well as IQ, might significantly help in definite differentiation of this syndrome. In pregnancy, oligohydramnion should indicate more detailed ultrasonographic examination, as ankylosed joints can be detected in utero.

Diagnostic Value of Electromyography in Children and Adolescents

The diagnostic accuracy in pediatric neurology has been considerably improved by new methods such as magnetic resonance imaging and molecular genetic analysis. However, standard diagnostic techniques continue to play an important role. The authors analyzed the diagnostic value of electromyography (EMG) and nerve conduction studies (NCS) in a retrospective study of 498 pediatric patients. The overall consistency between EMG results and the final clinical diagnosis in all children examined was 98%. In myogenic diseases, the concordance between EMG and clinical findings was lower (80%), because some patients with congenital myopathies showed normal EMG findings in this group. Peripheral neurogenic diseases were in all but one of the cases diagnosed correctly (99.5%). No decrease in diagnostic reliability was found in the younger age group. EMG and NCS examinations have to be adapted to the needs of children by an experienced examiner, but continue to be valuable diagnostic methods in pediatric neurology.

La Risonanza Magnetica muscolare nelle malattie neuromuscolari

We describe the main magnetic resonance features of neuromuscular diseases based on a series of 345 patients undergoing muscle MR scans. The study aimed to establish the use of this method in the diagnosis of neuromuscular disease, namely its ability to distinguish neurogenic forms from primary myopathy by analysing the location, extension and distribution of structural changes. A selective muscle involvement was encountered in some myogenic diseases and can be considered a characteristic feature of different diseases and hence an important aid in diagnosis. We propose that MR scanning be included among the instrumental tests required in the diagnosis of neuromuscular disease.

Dysphonia in infants

The definition of infant dysphonia is difficult because the physiological phonation itself may be extremely variable in newborns. In a wider sense, all voice utterings can be interpreted as dysphonia which deviate continuously in any of the parameters (timbre, pitch, intensity, or noise) from the normal. We differentiated 20 types of such pathological phonation. The most characteristic are: the hoarse (caused by inflammation or tumor of the vocal cords); the hollow (indicative of tracheal stenosis); the shrill (suggesting a CNS damage); the bleating (pathognostic of Down syndrome); the faint (a result of myogenic diseases); and the mewing cry (etiology: cri-du-chat syndrome). In a narrower sense dysphonia in infants is a kind of pathological phonation without evidence of neurological alteration or chromosomal aberration and without a verified laryngeal lesion. These infants utter pressed, harsh, or very high voice (hyperfunctional form) or a weak, inert cry (hypofunctional form). The dysphonic voice may be characterized also by sudden change in melody or in pitch (glide, shift, break, bitonality) and by turbulent noises. This type of newborn dysphonia is a result of the immature innervation of the larynx, it gradually improves and lateron spontaneously disappears. Perceptual evaluation, endoscopy, and acoustic analysis yield useful diagnostic information.

Fat infiltration, atrophy and hypertrophy of skeletal muscles demonstrated by X-ray computed tomography in neurological patients.

Since 1982, we have used X-ray computed tomography (CT) to study the skeletal muscles of neurological patients. We present here the findings in 23 patients with myogenic and 29 patients with neurogenic diseases. The method is convenient to demonstrate fat infiltration, atrophy and hypertrophy of skeletal muscles, but is of little help in differentiating between the 2 disease categories or individual diagnoses. The maximal isometric voluntary force of m. quadriceps femoris was measured in 13 of the patients with neurogenic, and in 10 of the patients with myogenic diseases. The power was compared with the cross-sectional area and the structural changes observed in the parenchyme of the muscles in the CT scans. A positive correlation was found between the size and the force of the muscle in both patient groups. The appearance of the muscular parenchyme was of little help to predict its function.

A new framework and computer program for quantitative EMG signal analysis.

Techniques for analyzing electromyographic signals, which estimate and detect potentials caused by active motor units in human striated muscles, are described. A framework within which these techniques are incorporated into a computer program for the quantitative analysis of EMG signals is then proposed. The resulting program allows the diagnosis of neurogenic and myogenic diseases by analyzing the waveforms of the motor unit potentials (MUP's). It also permits the research of the healthy and disturbed neuromuscular control loop by analyzing the point processes given by the activation of the single motor units.

Electromyography in pediatric neuromuscular disorders

A review of clinical electromyography is presented for the practicing pediatrician outlining the indications and limitations of this laboratory procedure. The electrical signals recorded from electrodes inserted in skeletal muscle have a characteristic pattern consisting of fibrillation and sharp wave potentials in diseases involving the lower motor neuron. As opposed to these neurogenic disorders myogenic diseases also may result in characteristic electrical alterations. The EMG findings in the more common pediatric neurologic disorders are reviewed. Recently facilities and equipment for the performance of peripheral nerve conduction studies have become more available to the pediatrician. Conduction rates are frequently prolonged in infectious and metabolic neuropathies.