After direct superior rectus muscle injection of BtA in rabbit eyes, we examined the ultrasructural changes of the muscles from 1 day to 8 weeks after injection. The most profound changes seen at electron microxcopic levels after BtA injedtion were early vacuolization of the sarcoplasmic structure, extensive damage of myofibril, degeneration of the postjunctional fold and widening of the synaptic cleft. Myofiber changes were reversible with no apparent long-term consequence. However, most of the degenerations of myoneuronal junction were still present in 8 weeks post-injedtion. Comparing myotoxic effects according to rabbit age, the botulinum toxin seems to make more severe histologic damage in the fibers of the two-month old than six-month old or older. AchE activity of injection group is mildly decrease in number of positive fibers rather than control group, which was not statistically significant in the quantitative analysis. In conclusion the early vacuolization and degeneration of the sarcoplasmic structure, and degeneration of the postjunctional folds after toxin injection in the muscles are most likely due to a direct myotoxic effect of BtA.
Botulinum Toxins* ; Botulinum Toxins, Type A ; Muscles ; Myofibrils

The effects of unilateral sciatic neurectomy on gastrocnemius muscle were studied in adult male rats. The morphological changes of both gastrocnemius muscles were observed by light and electron microscopy. Western blot analysis was performed to study the protein expression. Following the denervation, the affected muscle weights decreased significantly than normal. And the denervation led to a significant reduction in the area and diameter of muscle fibers on light microscopy. The affected muscle fibers showed the decreasing in size and the irregularity of myofibrilar arrangement on electron microscopy. On transverse view, the area of affected muscle fibers were smaller than normal. Their myofibrils were smaller and very irregular in size. The thin and thick myofilaments were not regular and partially lost. Mitochondria between myofibrils and subsarcolemmal area in affected muscle fibers were damaged and partially lost. The sacoplasmic reticulum and T-tubules were mostly lost and irregular. Some satellite cells were observed adjacent the muscle fiber, but they were inactive morphologically. On longitudinal view, most of myofibrils in affected muscle fibers were lost generally or partially although the their most sarcomeres were regularly arranged. Z line and myofilaments were lost partially and were partially irregularly arranged. The loss of thin myofilaments was more than that of thick myofilaments. Much debris of cell organelles were scattered among myofibrils. The expression of MyoD and myogenin were decrease significantly and the expression of p-mTOR and p-FOXO1 were decreased, too. On the other hand, MuRF1 was increased significantly. Taken together, the main effect of gastrocnemius muscle by sciatic neurectomy is the atrophy as a result of the loss of myofilaments and cell organelles through the decrease of protein synthesis and the increase of protein degradation.
Adult ; Animals ; Atrophy ; Blotting, Western ; Denervation ; Hand ; Humans ; Light ; Male ; Microscopy ; Microscopy, Electron ; Mitochondria ; Muscle, Skeletal ; Muscles ; Myofibrils ; Myogenin ; Organelles ; Proteolysis ; Rats ; Reticulum ; Sarcomeres ; Sciatic Nerve ; Weights and Measures

Muscle wasting is commonly seen in patients with sepsis as a consequence of the catabolic response in skeletal muscle. Muscle wasting can occur in cases that have an imbalance between degradation and synthesis of muscle proteins. Although decrements in the synthesis of muscle proteins may contribute to sepsis-induced muscle wasting, it has been recognized that increments in its degradation play a more essential role in muscle wasting. Muscle wasting in sepsis patients has some significant clinical consequences such as reduced ambulation and exercise tolerance, and an increased risk for pulmonary and thromboembolic complications. Several mechanisms have been proposed for sepsis-induced muscle wasting. Increased proteolysis via the ubiquitin-proteasome pathway and the calpains system is one of the principal mechanisms of muscle wasting induced by sepsis. Calpains are activated by calcium, which increases in patients with sepsis. The activation of the calpains system disrupts the sarcomere of the myofibrils, resulting in the release of myofilaments that are subsequently ubiquitinated and degraded by the 26S proteasome complex. Recent studies have suggested that transcriptional factors such as NF-kappaB and FoxO, and the apoptosis and autophagy-lysosome pathways may also be involved in sepsis-induced muscle wasting. This review briefly summarizes the contribution of these mechanisms of muscle wasting in patients with sepsis and the possible therapeutic agents to treat it.
Apoptosis ; Atrophy ; Calcium ; Calpain ; Exercise Tolerance ; Humans ; Muscle Proteins ; Muscle, Skeletal ; Muscles ; Myofibrils ; NF-kappa B ; Proteasome Endopeptidase Complex ; Proteolysis ; Sarcomeres ; Sepsis ; Ubiquitin ; Walking

Cap myopathy is pathologically characterized by cap structures comprising well-demarcated areas under the sarcolemma and containing deranged myofibrils and scattered Z-disks. Clinically it presents with slowly progressive muscle weakness, myopathic face, and frequent respiratory insufficiency. Four genes have been reported to be associated with the disease: TPM2, TPM3, ACTA1, and NEB. Here we describe that a patient presenting with mild limb weakness with facial affection showed cap structures on muscle pathology and carried a heterozygous TPM3 mutation.
Extremities ; Humans ; Muscle Weakness ; Muscular Diseases* ; Mutation, Missense* ; Myofibrils ; Pathology ; Respiratory Insufficiency ; Sarcolemma ; Tropomyosin

A 12-year-old girl presented with a ciliary body mass that measured approximately 13 X 10 mm in size. The tumor was excised through cyclectomy. The light microscopic apprearance resembled neurogenic neoplasm such as neurofibroma or schwannoma. However, some tumor cells included fasciculus which is a characteristic feature of myogenic tumor. Immunohistochemistry assay and electron microscopic examination revealed smooth muscle nature including myofilaments with dense bodies and established the diagnosis as mesectodermal leiomyoma in the ciliary body. To our best knowledge, our patient is the youngest among the ciliary body leiomyoma cases ever reported.
Child ; Ciliary Body* ; Diagnosis ; Female ; Humans ; Immunohistochemistry ; Leiomyoma* ; Muscle, Smooth ; Myofibrils ; Neurilemmoma ; Neurofibroma

BACKGROUND: Cadmium, an environmental pollutant, has implicated in the pathogenesis of cardiovascular diseases. Biochemical and pathophysiological changes characterized by arterial hypertension, accelerated cholesterol plaque formation on arterial walls, cardiac conduction abnormalities, and reduction in myocardial contractility have been reported in experimental animals chronically exposed to low concentration of cadmium. This study was undertaken to evaluate the ultrastructural changes of the cardiac muscle in rats exposed to cadmium chloride and to ascertain whether these changes are modified after discontinuation of cadmium feeding. METHOD: Wistar strain rats(body weight 200~250gram) were injected intraperitoneally once weekly with 3.75mg/kg of cadmium chloride for 10 weeks and were sacrificed at 1 day, 1 week and 2 weeks after discontinuation of cadmium administration. RESULT: Ultrastructure if rat cardiac muscle fibers after cadmium administration revealed that mitochondria were increased in number and their cristae were severely damaged. Cardiac myofibrils and myofilaments were reduced. Z-disc were partly dislocated and A-bands and I-bands were not clearly defined. Irregularly arranged intercalated disc and disrupted sarcolemma were also found. These structural alterations resulting from cadmium feeding were partly reduced after removal of cadmium exposure for 2 weeks. These structural alterations resulting from cadmium feeding were partly reduced after removal of cadmium exposure for 2 weeks. CONCLUSIONS: It is suggested that exposure to cadmium chloride was associated with cardiac ultrastructural changes which might be responsible for physiologic abnormalities and these alterations may be partly reversible after discontinuation of cadmium administration.
Animals ; Cadmium Chloride* ; Cadmium* ; Cardiovascular Diseases ; Cholesterol ; Hypertension ; Mitochondria ; Myocardium* ; Myofibrils ; Rats* ; Sarcolemma

Medullomyoblastoma is a very rare central nervous system tumor and is regarded to be a variant of medulloblastoma showing a rhabdomyoblastic component. We found 32 cases of medullomyoblastoma in English literature. We recently experienced a case of a cerebellar medullomyoblastoma with neuronal differentiation in a 15-year-old girl who displayed headaches and vomiting. The tumor displayed extensive neuronal and myoblastic differentiation on microscopic and immunohistochemical examination. On ultrastructural study, the tumor obviously demonstrated rhabdomyoblastic features showing myofilaments composed of actin and myosin with well developed Z-bands.
Actins ; Adolescent ; Central Nervous System ; Female ; Headache ; Humans ; Medulloblastoma* ; Myoblasts ; Myofibrils ; Myosins ; Neurons* ; Vomiting

Light and electron microscopic obserbations of developing heart wall of zebrafish, which has been recently used for developmental studies of many organs, were performed. Heart tissue was obtained from adult and 24, 48 and 72 hour embryos of zebrafish. Heart wall of adult zebrafish was composed of 3 typical layers, endocardium, myocardium and epicardium, as ones of other vertebrates. Heart wall of 24 hour embryo was composed of primitive myocytes. Myofibrils in myocytes at this period was found as assembly of myofilaments, 500~1,000 nm sized and 5~10 layered. Heart of 48 hour embryo has ventricle and atrium. Ventricular wall of was composed of endocardium, myocardium and incomplete epicardium. Atrial wall at 48 hour embryo was composed of endocardium and myocardium. Development of myocytes in ventricle was earlier than those of atrium, and myofibrils with Z disc were found first at 48 hour embryo. Heart wall of 72 hour embryo was morphologically similar to that of 48 hour embryo, but development of myocytes was more progressed. Specific atrial granules of 100~200 nm size appeared very rarely at 24 hour embryo and its numbers increased gradually at 48 and 72 hour embryos in myocytes of atrium as well as the ventricle. Specific atrial granules were consider as ones containing atrial natriuretic peptide (ANP).
Adult ; Embryonic Structures ; Endocardium ; Heart* ; Humans ; Muscle Cells ; Myocardium ; Myofibrils ; Pericardium ; Vertebrates ; Zebrafish*

Childhood onset nemaline myopathy, first described in 1963 by Shy, et al and Conen, et al, is rare congenital myopathy, characterized by nonprogressive or slowly progressive muscle weakness associated with rod-like structures in muscle fibers, often with dysmorphic features. This myopathy was confirmed by muscle biopsy. The light microscopic features noted generally small round fibers that showed variation in size and occasional internal nuclei and characteristic rod bodies that could be demonstrated in the longitudinal sections stained with modified Gomori trichrome stain. Electromicroscopically there were accumulations of numerous irregular electron dense materials scattered between the myofibrils, particularly under the sarcolemma and enlargement and streamimg of the Z disk. We report a case of childhood onset nemaline myopathy in Korea in a 7 year- old boy who had nonprogressive muscle weakness of the limbs with a waddling gait.
Biopsy ; Extremities ; Gait ; Humans ; Korea ; Male ; Muscle Weakness ; Muscular Diseases ; Myofibrils ; Myopathies, Nemaline* ; Sarcolemma

Several clinical studies suggest substantial limitations of currently available positive inotropic substances, including beta1-adrenoceptor agonists and phosphodiesterase III inhibitors. Levosimendan, a myofilament calcium sensitizer with inotropic effects, increases myocardial performance without substantial changes in oxygen consumption and with neutral effects on heart rhythm. In addition, levosimendan has vasodilatory effects that are achieved by stimulation of adenosine triphosphate-dependent potassium channels. This review article briefly discusses the pharmacology of levosimendan and evaluates current available evidence to assess the safety and efficacy of levosimendan.
Adenosine ; Calcium ; Cyclic Nucleotide Phosphodiesterases, Type 3 ; Heart ; Myofibrils ; Oxygen Consumption ; Pharmacology ; Potassium Channels