BACKGROUND AND PURPOSE: Hyperkalemic periodic paralysis (hyperKPP) is a muscle sodium-ion channelopathy characterized by recurrent paralytic attacks. A proportion of affected individuals develop fixed or chronic progressive weakness that results in significant disability. However, little is known about the pathology of hyperKPP-induced fixed weakness, including the pattern of muscle involvement. The aim of this study was to characterize the patterns of muscle involvement in hyperKPP by whole-body magnetic resonance imaging (MRI). METHODS: We performed whole-body muscle MRI in seven hyperKPP patients carrying the T704M mutation in the SCN4A skeletal sodium-channel gene. Muscle fat infiltration, suggestive of chronic progressive myopathy, was analyzed qualitatively using a grading system and was quantified by the two-point Dixon technique. RESULTS: Whole-body muscle MRI analysis revealed muscle atrophy and fatty infiltration in hyperKPP patients, especially in older individuals. Muscle involvement followed a selective pattern, primarily affecting the posterior compartment of the lower leg and anterior thigh muscles. The muscle fat fraction increased with patient age in the anterior thigh (r=0.669, p=0.009), in the deep posterior compartment of the lower leg (r=0.617, p=0.019), and in the superficial posterior compartment of the lower leg (r=0.777, p=0.001). CONCLUSIONS: Our whole-body muscle MRI findings provide evidence for chronic progressive myopathy in hyperKPP patients. The reported data suggest that a selective pattern of muscle involvement-affecting the posterior compartment of the lower leg and the anterior thigh-is characteristic of chronic progressive myopathy in hyperKPP.
Channelopathies ; Humans ; Leg ; Magnetic Resonance Imaging* ; Muscles ; Muscular Atrophy ; Muscular Diseases* ; Paralysis, Hyperkalemic Periodic* ; Pathology ; Thigh

As an important exercise and energy metabolism organ of the human body, the normal maintenance of skeletal muscle mass is essential for the body to perform normal physiological functions. The autophagy-lysosome (AL) pathway is a physiological or pathological mechanism that is ubiquitous in normal and diseased cells. It plays a key role in the maintaining of protein balance, removing damaged organelles, and the stability of internal environment. The smooth progress of the autophagy process needs to go through multiple steps, which are completed under the coordinated action of multiple factors. Autophagy maintains the muscle homeostasis of a healthy body by removing cell components such as damaged myofibrils and isolated cytoplasmic proteins. Autophagy could also provide the initial energy required for cell proliferation, promote muscle regeneration and remodeling after injury. At the same time, autophagy disorder is also an important cause of age-related skeletal muscle atrophy. Autophagy could affect the response of skeletal muscle to exercise, and increasing the level of basic autophagy is beneficial to improve the adaptive response of skeletal muscle to exercise. This article summarizes the role and pathways of autophagy in the maintenance of skeletal muscle quality, in order to provide effective rehabilitation strategies for clinical prevention and treatment of muscle atrophy.
Autophagy/physiology* ; Exercise/physiology* ; Humans ; Muscle, Skeletal/pathology* ; Muscular Atrophy/pathology* ; Signal Transduction

Myotubular or centronuclear myopathy(MTM) is a rare congenital myopathy, which is characterized by predominance and atrophy of type 1 fibers and centrally located nuclei in muscle pathology. The clinical features and severity are quite variable. MTM is classified as three forms according to the inheritance pattern : autosomal dominant, autosomal recessive and X-linked recessive. The authors present familial myotubular myopathy, suggestive of X linked, occurred in a sibling with intrafamilial clinical variability.
Atrophy ; Humans ; Inheritance Patterns ; Muscular Diseases ; Myopathies, Structural, Congenital* ; Pathology ; Siblings*

This experiment was designed to explore the correlation between the mechanism of immobilization-induced skeletal muscle atrophy and the apoptosis of muscular cells. The models of skeletal muscle atrophy induced by immobilization for different length of time were established according to Sievanen II methods. 24 rabbits, each of them having one hind leg fixed by the tubal plaster and the other one free as control, were randomly divided into four groups depending on time of fixation (3, 7, 14, and 28 days respectively). The animals were sacrificed by the end of fixation. TdT-mediated d-UTP nick end labeling (TUNEL) was used to investigate the apoptotic muscle cells in the animal's bone. By comparing the apoptotic muscle cells with the morphology of the skeletal muscle, the correlation between cell apoptosis and skeletal muscle atrophy were analyzed. Apoptotic muscle cells did appear after immobilization in the atrophied skeletal muscle. In various groups, some cells with false positive stained TUNEL were found in the atrophic muscle, which could be distinguished from apoptotic cells by their characteristics. In conclusion, cell apoptosis participates in the process of skeletal muscle atrophy induced by immobilization; the amount of apoptotic cells is strongly associated with the time of immobilization, its peak appears on the 14th day of immobilization; the distribution of apoptotic skeletal muscle cell varies with the time of fixation. The severity of skeletal muscle atrophy is associated with the degree of the muscle cell apoptosis.
Animals ; Apoptosis ; physiology ; Immobilization ; In Situ Nick-End Labeling ; Muscle, Skeletal ; pathology ; Muscular Atrophy ; etiology ; Rabbits

Angiotensin II ; metabolism ; Animals ; Male ; Muscle, Skeletal ; Muscular Atrophy ; etiology ; metabolism ; pathology ; Rats ; Rats, Sprague-Dawley

Animals ; Hindlimb ; Male ; Mice ; Mice, Inbred C57BL ; Muscle Fibers, Skeletal ; Muscle, Skeletal/pathology* ; Muscular Atrophy

OBJECTIVETo compare the effect of botulinum neurotoxin A (BTA) and denervation in inducing masseter muscle atrophy in rabbits to provide experimental evidence for the safe clinical application of BTA.

METHODSSeventy-five healthy adult New Zealand white rabbits were randomized equally into denervation group, BTA group and normal control group. In the former two groups, the rabbits were subjected to right masseter muscle denervation and botulinum (3 µg/kg) injection at the muscle, respectively, with the left side as the control. The thickness of the denervated masseter was determined using B type ultrasound and its weight measured after the treatment.

RESULTSThe thickness of the masseter muscle on the experimental side was significantly decreased to 50.80% and 54.07%, and its weight to 66.80% and 56.16% of the normal level after denervation and BTA injection, respectively.

CONCLUSIONBTA-induced denervation produces less potent atrophy-inducing effect on skeletal muscle than surgical denervation. BTA causes atrophy mainly at the injection site of the target muscle without significant diffusion or toxicity to the muscular cells.

Animals ; Botulinum Toxins, Type A ; toxicity ; Female ; Male ; Masseter Muscle ; drug effects ; pathology ; Muscle Denervation ; Muscular Atrophy ; pathology ; Rabbits

Actins ; metabolism ; Adult ; Amyloidosis ; pathology ; Diagnosis, Differential ; Female ; Humans ; Intestinal Pseudo-Obstruction ; metabolism ; pathology ; Lupus Erythematosus, Systemic ; pathology ; Muscular Atrophy ; pathology ; Scleroderma, Systemic ; pathology ; Young Adult

OBJECTIVESpinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease. It is characterized by selective loss of spinal cord motor neurons leading to muscle atrophy and is the result of mutation or deletion of the survival motor neuron (SMN) gene. Currently, there are no effective therapies for this disease. Stem cell therapy is a new prospect for SMA patients. This study aimed to investigate whether mesenchymal stem cells (MSCs) can be differentiated into neuron-like cells (NLCs) in SMA patients in order to provide a basis for stem cell therapy for SMA.

METHODSSMA was definitively diagnosed using polymerase chain reaction-restriction fragment length polymerphhism (PCR-RFLP). Two children without SMN1 gene deletion were used as controls. MSCs were isolated and purified from SMA patients and controls, and induced into NLCs by bFGF and baicalin. The NLCs were identified by immunofluourescence staining with NSE and NF monoclonal antibodies.

RESULTSSMA patients showed the deletion of SMN1 exon 7. The morphous and proliferative speed of MSCs between SMA patients and controls were similar. After 6-day induction, MSCs of the two groups displayed similar morphology to that of neurons, with long processes forming extensive networks. NSE and NF, the neuronal markers, were detected in the differentiated NLCs of the two groups.

CONCLUSIONSSMN1 deletion appears not to affect the proliferation and differentiation of MSCs. MSCs of SMA patients can be differentiated into NLCs.

Adolescent ; Cell Differentiation ; Cell Proliferation ; Child ; Female ; Humans ; Male ; Mesenchymal Stromal Cells ; cytology ; Muscular Atrophy, Spinal ; pathology ; Neurons ; cytology

BACKGROUND: Delaminated rotator cuff tear is known to be a degenerative tear having a negative prognostic effect. This study undertook to compare the anatomical and clinical outcomes of delaminated tears and single layer tears. METHODS: Totally, 175 patients with medium to large rotator cuff tears enrolled for the study were divided into 2 groups, based on the tear pathology: single layer tear (group 1) and delaminated tear (group 2). Preoperatively, length of the remnant tendon, muscle atrophy of supraspinatus (SS), and fatty degeneration of SS and infraspinatus (IS) muscles were assessed on magnetic resonance imaging (MRI). For follow-up, the repair integrity of the rotator cuff was evaluated by ultrasonography. Clinical outcomes were assessed by evaluating the Constant score (CS) and Korean Shoulder Score (KSS). RESULTS: Retears were detected in 6 cases of group 1 (6.5%) and 11 cases of group 2 (13.3%). Although higher in group 2, the retear rate was significantly not different (p=0.133). Preoperative MRI revealed length of remnant tendon to be 15.46 ± 3.60 mm and 14.17 ± 3.16 mm (p=0.013), and muscle atrophy of SS (occupation ratio) was 60.54 ± 13.15 and 56.55 ± 12.88 (p=0.045), in group 1 and group 2, respectively. Fatty degeneration of SS and IS in both groups had no significant differences. Postoperatively, no significant differences were observed for CS and KSS values between the groups. CONCLUSIONS: Delaminated rotator cuff tears showed shorter remnant tendon length and higher muscle atrophy that correlate to a negative prognosis. These prognostic effects should be considered during delaminated rotator cuff tear treatment.
Follow-Up Studies ; Humans ; Magnetic Resonance Imaging ; Muscles ; Muscular Atrophy ; Pathology ; Prognosis ; Rotator Cuff ; Shoulder ; Tears ; Tendons ; Ultrasonography