Establishment of a new rehabilitation program using masticatory training food for jaw deformity patients.

Background/purpose: Patients with jaw deformities may show a reduction in masticatory function as a result of postoperative hypofunction. This study aimed to establish a novel rehabilitation program using a commercially available masticatory training food for patients with jaw deformities after orthognathic surgery. Materials and methods: Nine patients with mandibular prognathism (the training group: n = 5, and the non-training group: n = 4) and 6 control participants with normal occlusion were included in this study. For the rehabilitation program with masticatory exercise, patients were instructed to chew the training food once a day for 60 days starting from 10 days after the surgery. The effects of the rehabilitation program were assessed by determining the maximum bite force (MBF) and the masticatory performance (MP). Clinical assessments were performed just before orthognathic surgery (Pre) and at 10 days (T0), 1 month (T1), 2 months (T2), and 3 months (T3) after surgery. Results: Compared with the non-training group, the training group showed a trend toward greater recovery amount of MBF from Pre to T3, and a significantly greater recovery amount in MP (p < 0.05) from Pre to T3. When the time-series change of MP was evaluated in both groups from T0 to T3, a significant difference was observed in the interaction terms (p = 0.03). This result indicates that the effectiveness of the training may be demonstrated by following the postoperative course further. Conclusion: The rehabilitation using this training food may become a useful method for postoperative hypofunction in patients with jaw deformities.

Treatment decision of camouflage or surgical orthodontic treatment for skeletal Class III patients based on analysis of masticatory function.

Background/purpose: Surgical orthodontic treatment is recommended for patients with severe dentoskeletal discrepancies, while camouflage orthodontic treatment is recommended for patients with mild to moderate discrepancies. However, the decision as to which treatment should be chosen is complicated. The purpose of this study was to determine differences in masticatory function in patients who underwent camouflage and surgical orthodontic treatment for skeletal Class III malocclusion, as well as the usefulness of Wits appraisal in treatment decision based on masticatory functional analysis. Materials and methods: The study subjects were 45 patients with skeletal Class III malocclusion (15 cases with camouflage orthodontics and 30 cases with orthognatic surgery) and 12 individuals with normal occlusion. We analyzed the pre-treatment records of electromyographic activities of masseter and temporalis muscles and jaw movements. Results: There were no significant differences in various functional measurements between the camouflage and surgery groups. However, there were significant but not strong correlations between ANB and both masseter muscle activity (r = 0.36, p < 0.01) and expression ratio of abnormal chewing (r = -0.54, p < 0.01). Division of patients into two groups using a cutoff value of -6.0 mm for Wits appraisal showed a significant difference in masseter muscle activity between -6.0 mm or less group and the control (p < 0.01) but none between more than -6.0 mm group and the control. Conclusion: Camouflage orthodontic treatment is inappropriate for patients with relatively severe dentoskeletal discrepancies. Wits appraisal of -6.0 mm is a potentially useful parameter for treatment decision.

A case of transpetrosal penetrating head injury near the sigmoid sinus.

BACKGROUND: Penetrating brain injury is relatively rare, which occurs in 0.4% of all head trauma. In past reports, the orbit, nasal cavity, and oral cavity are the most common routes of entry of foreign substances into the skull. In this case report, we experienced a rare case of head trauma who injury through the petrosal bone. To the best of our knowledge, there is no similar literature. CASE DESCRIPTION: A 69-year-old man accidentally fell from a stepladder with a height of 3 m. There was a sprinkler on the ground, and it went through his posterior part of the right auricle at the collision. He was alert on admission. However, neurological examination showed right trigeminal, abducens, and facial nerve palsy. Computed tomography was performed, and it revealed that the objects penetrated the petrosal bone. Furthermore, it caused traumatic subarachnoid hemorrhage and acute subdural hemorrhage. Fortunately, it did not reach any cerebral artery and cerebral parenchyma. Immediately it was surgically removed with a good outcome. CONCLUSION: When suspected sigmoid sinus injury in head penetrating injury, craniotomy should be considered with bleeding from the sigmoid sinus during surgery.

A Case of Coil Embolization for a Ruptured Anterior Spinal Artery Aneurysm Associated with Bilateral Vertebral Artery Occlusion.

Anterior spinal artery (ASA) aneurysms are rare, and the majority are associated with vascular lesions such as arteriovenous malformations, moyamoya disease, and aortic stenosis. Herein, we report a case of a ruptured anterior spinal artery aneurysm caused by bilateral vertebral artery (VA) occlusion, which was treated by coil embolization. An 83-year-old man was found collapsed at home, and was brought in by emergency. His consciousness level was I-1 on the Japan Coma Scale, and there were no symptoms such as paralysis in the extremities. Computed tomography showed Fisher 3 subarachnoid hemorrhage, while magnetic resonance angiography showed an aneurysm in the right VA. Digital subtraction angiography showed bilateral VA occlusion, and an aneurysm was found on the dilated ASA as a collateral circulation. Coil embolization was performed after confirmation of no hemodynamic problems. No postoperative adverse events were observed. Coil embolization may be an effective treatment for ruptured aneurysms of the ASA.

Successful endovascular treatment of a ruptured bihemispheric posterior inferior cerebellar artery aneurysm: illustrative case.

BACKGROUND: Normal posterior inferior cerebellar artery (PICA) anatomy is highly variable, but bihemispheric PICA crossing the midline to supply the vascular territory of bilateral cerebellar hemisphere is rare. Herein, the authors reported a rare case of ruptured aneurysm that was associated with bihemispheric PICA and successfully treated endovascularly. OBSERVATIONS: A 46-year-old woman presented with sudden headache and loss of consciousness because of an intraventricular hemorrhage due to a ruptured aneurysm that was associated with the bihemispheric PICA. Angiography revealed that the aneurysm was located at the bifurcation between the bihemispheric PICA and the bilateral distal PICA. The ruptured aneurysm was successfully occluded using coil embolization, which preserved the parent artery with no procedural-related complication. LESSONS: To the best of the authors' knowledge, this was the first report of a ruptured aneurysm associated with bihemispheric PICA being successfully treated endovascularly. Aneurysm formation may be accelerated by hemodynamic stress and vascular fragility. For neurosurgeons and neurointerventionalists, it is important to understand the anatomical variation of PICA, especially bihemispheric PICA, which is a potential risk factor for a fatal stroke.

Low-intensity pulsed ultrasound enhances the rate of lateral tooth movement and compensatory bone formation in rats.

INTRODUCTION: Because mechanical stimulation of the periodontal ligament by low-intensity pulsed ultrasound (LIPUS) has been shown to increase the speed of bone remodeling, this study aimed to examine the effects of LIPUS stimulation on the rate of tooth movement and bone remodeling during lateral tooth movement. METHODS: Twelve-week-old Wistar rats were divided into 2 groups. The LIPUS group received experimental tooth movement with LIPUS stimulation, and the tooth movement (TM) group were provided experimental tooth movement without LIPUS. For each group, the upper right first molars were moved buccally with fixed appliances. LIPUS exposure was placed in the region corresponding to the right maxillary first molar. Three days after tooth movement, tartrate-resistant acid phosphatase was examined. Fourteen days after tooth movement, the intermolar width, bone mineral content, and bone volume fraction were analyzed by micro-computed tomography, and newly formed bone was measured histomorphometrically. RESULTS: The number of TRAP-positive cells in the compressed region was higher in the LIPUS group. The intermolar width was significantly higher in the LIPUS group than in the TM group. The alveolar bone around the maxillary first molar showed no differences in bone mineral content and bone volume fraction between the LIPUS and TM groups. The LIPUS group exhibited a more significant amount of newly formed alveolar bone than the TM group. CONCLUSIONS: The present study provides evidence of the beneficial effects of LIPUS on the lateral tooth movement.

Effects of functional training after orthognathic surgery on masticatory function in patients with mandibular prognathism.

BACKGROUND/PURPOSE: Even after surgical orthodontic treatment, the level of masticatory function in patients with jaw deformities is still lower than that of healthy subjects. The purpose of this study was to evaluate the effects of functional training program using gum chewing exercise after orthognathic surgery on masticatory function in patients with mandibular prognathism. MATERIALS AND METHODS: The study subjects were 16 patients with mandibular prognathism who underwent orthognathic surgery and 8 individuals with normal occlusion. Patients were divided into two groups (training group and non-training group; n = 8 per group). Functional training included gum chewing exercise and patient-education about masticatory function. The training; gum chewing exercise of 5 min twice a day for 90 days, started at 3 months after surgery. For each subject, electromyographic activities of masseter and temporalis muscles during maximum voluntary clenching (MVC) and jaw movement during gum chewing were recorded before and after surgical orthodontic treatment. Two parameters; activity index (AI: ratio of activity of masseter and temporalis muscles) and error index (EI: ratio of the number of abnormal chewing patterns), were used. RESULTS: In the training group, the AI value during MVC increased significantly and the EI value during gam chewing decreased significantly after surgical orthodontic treatment (AI: p < 0.01; EI: p < 0.01), indicating the improvement of activity balance of masseter and temporalis muscles and conversion of the jaw movement from abnormal to normal pattern (p < 0.01). CONCLUSION: Our findings suggested that functional training using the gum chewing and patient-education exercise improved masticatory function in patients with mandibular prognathism.

Treatment Strategy for Progressive Cervical Internal Carotid Artery Stenosis Under Restriction of the Use of Antiplatelet Drugs.

BACKGROUND: Acute ischemic stroke caused by cervical internal carotid artery stenosis (ICS) with altered consciousness and progressive paralysis leads to a poor neurologic prognosis. When such a patient is brought to the hospital in the hyperacute phase, intravenous tissue plasminogen activator is first administered. However, when an indwelling carotid artery stent is required after administration, physicians often hesitate to use antithrombotic drugs. In this report, we propose performing staged angioplasty (SAP) for such cases. METHODS: Four patients were retrospectively investigated. In all 4 patients, we immediately performed only percutaneous transluminal angioplasty (PTA) without antiplatelet drugs. If both cerebral perfusion on angiography and neurologic findings improved, no additional treatment was provided; otherwise, emergency carotid artery stenting (eCAS) was performed. In PTA-successful cases, eCAS or carotid endarterectomy (CEA) was performed with single or dual antiplatelet drugs at a later date. RESULTS: The success rate of PTA was 50% (2 of 4), and the overall treatment success rate was 100% (4 of 4). Three patients had favorable outcomes (modified Rankin Scale [mRS] score 0-2), but unfortunately, 1 patient had severe disability (mRS score >3) on discharge. The PTA-successful patients had no perioperative complications. On the other hand, 1 of the 2 patients who underwent eCAS experienced embolic complications, including distal embolization. CONCLUSIONS: In this investigation, both eCAS and SAP could be performed safety. However, performing SAP first without antiplatelet drugs to avoid hemorrhagic complications and cerebral hyperperfusion syndrome appears to have considerable validity.

Protective Effects of Low-Intensity Pulsed Ultrasound on Mandibular Condylar Cartilage Exposed to Mechanical Overloading.

The aim of this study was to assess the effect of low-intensity pulsed ultrasound (LIPUS) application on rat temporomandibular joints (TMJs) with early-stage of osteoarthritis-like conditions induced by mechanical overloading. Fifteen-week-old male Wistar rats were divided into two experimental groups and a control group (n = 10 each). Both TMJs of all rats in one experimental group were subjected to mechanical overloading for 5 d, and those in the other experimental group were exposed to LIPUS for 20 min/d after overloading. Condyles were assessed using micro-computed tomography, histology and histomorphometry. LIPUS treatment attenuated cartilage degeneration, decreased the number of osteoclastic cells and restored the expression of aggrecan after an initial decrease induced by mechanical overloading. These results indicate that LIPUS may have a protective effect on the early progression of TMJ osteoarthritis.

Occurrence of Trigger Finger Following Carpal Tunnel Release.

Surgical treatment of carpal tunnel syndrome (CTS) was recently started in our department, and we noticed that the development of trigger finger (TF), with which neurosurgeons are generally unfamiliar, is not rare after such treatment. We summarized the clinical and pathogenetic aspects of TF and retrospectively analyzed the medical records of all 39 patients who underwent CTR in our department to investigate the occurrence of TF. In 39 patients with CTS, 46 surgical interventions were performed in our department. All surgical procedures were carried out by open release of the transverse carpal ligament under local anesthesia infiltration, but the distal forearm fascia was not released. The mean postoperative follow-up period was 21.1 ± 16.8 months. TF after CTR occurred in nine hands of eight patients (9 of 46 hands, 19.6%). The mean interval between CTR and TF onset was 5.3 ± 2.8 months. TF after surgical treatment of CTS is not rare; therefore, surgeons who treat CTS should understand the clinical features of TF and carefully assess affected patients, particulary at presentation and within 6 months postoperatively.

Effects of gum chewing exercise on maximum bite force according to facial morphology.

Development of the masticatory system is influenced by functional needs. Furthermore, masticatory exercise can improve masticatory function. The aim of this study was to evaluate the potential effect of the gum chewing exercise on the maximum bite force (MBF) in adult subjects with different facial morphologies. MBF was measured by a portable occlusal force gauge and lateral cephalogram was used for evaluation of craniofacial morphology in 19 individuals (7 males and 12 females) with a mean age of 25.4 years (SD ± 4.3). The volunteers underwent gum chewing exercise for 5 min twice a day for 4 weeks. MBF was measured before (T1) and after the 4-week exercise (T2). The facial morphology of the subjects was classified into the brachy (n = 7), mesio (n = 7), and dolicho (n = 5) facial types. In all three groups, exercise was associated with a significant increase in MBF, though the percent increase was highest in the dolicho facial type. We conclude that gum chewing exercise can improve masticatory performance, especially in individuals with dolicho facial morphology.

Effectiveness of presurgical nasoalveolar molding therapy on unilateral cleft lip nasal deformity.

OBJECTIVES: To evaluate the effectiveness of pre-surgical nasoalveolar molding (PNAM) in patients with unilateral cleft lip nasal deformities. Methods: This was a retrospective study involving 29 patients with unilateral cleft lip and palate defects, of whom 13 were treated with palatal devices with nasal stents (PNAM group) and 16 were treated with palatal devices without nasal stents or surgical tapes (control group). Submental oblique photographs and orthodontic models were longitudinally obtained at the initial visit (T1) and immediately before (T2) and  after cheiloplasty (T3). Asymmetry of the external nose, degree of columellar shifting, nasal tip/ala nose ratio, nasal base angle, interalveolar gap, and the sagittal difference in the alveolar gap were measured. The study was conducted in the Orthodontic Clinic at Tokushima University Hospital, Tokushima, Japan between 1997 and 2012. Results: At T1, there were no significant intergroup differences in the first 4 asymmetry parameters. At T2, the PNAM group showed a significant improvement in all values compared to the control group. At T3, the PNAM group showed significant improvement in nasal asymmetry and columellar shifting. Model analysis showed significantly greater changes in the inter-alveolar gap and the sagittal difference of the alveolar cleft gap from T1 to T2 in the PNAM group. Conclusion: The use of PNAM is indispensable for pre-surgical orthodontic treatment at the early postnatal age.

Skeletal anchorage for intrusion of bimaxillary molars in a patient with skeletal open bite and temporomandibular disorders.

The treatment of severe skeletal anterior open bite is extremely difficult in adults, and orthognathic surgery is generally selected for its treatment. We report the case of an 18-year-old adult patient with skeletal anterior open bite and temporomandibular disorders who was successfully treated using temporary anchorage devices. She had an open bite of -2.0 mm and an increased facial height. Miniplates were implanted in both the maxilla and mandible, and molar intrusion resulted in counterclockwise rotation of the mandible over a period of 12 months. After active treatment, her upper and lower first molars were intruded by approximately 2 mm and her overbite became +2.5 mm. Her retrognathic profile improved with counterclockwise rotation of the mandible. Orthodontic treatment aided with skeletal anchorage is beneficial for intrusion of bimaxillary molars in patients with anterior open bite.

Co-Administration of Myostatin-Targeting siRNA and ActRIIB-Fc Fusion Protein Increases Masseter Muscle Mass and Fiber Size.

Myostatin, a member of the TGF-ß superfamily, is a negative regulator of skeletal muscle cell growth and differentiation, and binds with high affinity to the activin type IIB receptor (ActRIIB). The soluble ligand-binding domain of ActRIIB fused to the Fc domain of IgG (ActRIIB-Fc) potently binds and inhibits TGF-ß family members in muscle, leading to rapid and marked muscle growth. The present study was designed to assess the effectiveness of the co-delivery of myostatin-targeting siRNA (Mstn-siRNA) and ActRIIB-Fc into skeletal muscle as a potential treatment of atrophic myopathies. Eleven-week-old, male C57BL/6 mice were injected with atelocollagen (ATCOL)-mediated Mstn-siRNA with/without ActRIIB-Fc locally into the masseter muscle twice a week. Inhibition of myostatin function by the combination of Mstn-siRNA and ActRIIB-Fc increased muscle weight and myofibril size in murine masseter muscle. Real-time RT-PCR analysis revealed significant downregulation of myostatin mRNA expression in both the Mstn-siRNA-treated and the combination treatment group. Furthermore, myogenin mRNA expression was upregulated in the combination treatment group, while MuRF-1 and Atrogin-1 mRNA expression was downregulated compared to administration of each compound alone. These findings suggest that double inhibition of myostatin is a potentially useful treatment strategy to increase muscle mass and fiber size and could be a useful treatment of patients with various muscle atrophies, including muscular dystrophy.

Long-term follow-up of a patient with achondroplasia treated with an orthodontic approach.

We successfully treated a patient with achondroplasia with conventional orthodontic techniques. It was followed by long-term retention. The patient, a 12-year-old boy, had chief complaints of occlusal disturbance and mandibular protrusion. He had been diagnosed with achondroplasia and had growth hormone treatment in his early teenage years. His facial profile was concave with a bulging forehead and a retrognathic maxilla. It was characterized by a skeletal Class III jaw-base relationship with a retropositioned maxilla. At the age of 12 years 9 months, maxillary protraction was initiated with a reverse headgear; for 2 years 6 months, the maxillomandibular growth was controlled. After the growth spurt, at the age of 15 years 6 months, leveling and alignment of both dental arches were started with preadjusted edgewise appliances. After 83 months of multibracket treatment, an acceptable occlusion with a Class I molar relationship and an adequate interincisal relationship was achieved, despite the simultaneous marked vertical growth of the mandible. The resultant occlusion was stable during a 6-year retention period, although considerable forward-downward mandibular growth was observed. Conclusively, our results indicated the necessity of long-term observation in this patient with achondroplasia, especially because of the persistent mandibular growth.

Effects of Decreased Occlusal Loading during Growth on the Mandibular Bone Characteristics.

BACKGROUND: Bone mass and mineralization are largely influenced by loading. The purpose of this study was to evaluate the reaction of the entire mandibular bone in response to decreased load during growth. It is hypothesized that decreased muscular loading will lead to bone changes as seen during disuse, i.e. loss of bone mass. METHODS AND FINDINGS: Ten 21-day-old Wistar strain male rats were divided into two groups (each n=5) and fed on either a hard- or soft-diet for 11 weeks. Micro-computed tomography was used for the investigation of bone mineralization, bone volume, bone volume fraction (BV/TV) and morphological analysis. Mandibular mineralization patterns were very consistent, showing a lower degree of mineralization in the ramus than in the corpus. In the soft-diet group, mineralization below the molars was significantly increased (p<0.05) compared to the hard diet group. Also, bone volume and BV/TV of the condyle and the masseter attachment were decreased in the soft-diet group (p<0.05). Morphological analysis showed inhibited growth of the ramus in the soft-diet group (p<0.05). CONCLUSION: Decreased loading by a soft diet causes significant changes in the mandible. However, these changes are very region-specific, probably depending on the alterations in the local loading regime. The results suggest that muscle activity during growth is very important for bone quality and morphology.

Flavones Inhibit LPS-Induced Atrogin-1/MAFbx Expression in Mouse C2C12 Skeletal Myotubes.

Muscle atrophy is a complex process that occurs as a consequence of various stress events. Muscle atrophy-associated genes (atrogenes) such as atrogin-1/MAFbx and MuRF-1 are induced early in the atrophy process, and the increase in their expression precedes the loss of muscle weight. Although antioxidative nutrients suppress atrogene expression in skeletal muscle cells, the inhibitory effects of flavonoids on inflammation-induced atrogin-1/MAFbx expression have not been clarified. Here, we investigated the inhibitory effects of flavonoids on lipopolysaccharide (LPS)-induced atrogin-1/MAFbx expression. We examined whether nine flavonoids belonging to six flavonoid categories inhibited atrogin-1/MAFbx expression in mouse C2C12 myotubes. Two major flavones, apigenin and luteolin, displayed potent inhibitory effects on atrogin-1/MAFbx expression. The pretreatment with apigenin and luteolin significantly prevented the decrease in C2C12 myotube diameter caused by LPS stimulation. Importantly, the pretreatment of LPS-stimulated myoblasts with these flavones significantly inhibited LPS-induced JNK phosphorylation in C2C12 myotubes, resulting in the significant suppression of atrogin-1/MAFbx promoter activity. These results suggest that apigenin and luteolin, prevent LPS-mediated atrogin-1/MAFbx expression through the inhibition of the JNK signaling pathway in C2C12 myotubes. Thus, these flavones, apigenin and luteolin, may be promising agents to prevent LPS-induced muscle atrophy.

Prevention of skeletal muscle atrophy in vitro using anti-ubiquitination oligopeptide carried by atelocollagen.

Skeletal muscle atrophy occurs when the rate of protein degradation exceeds that of protein synthesis in various catabolic conditions, such as fasting, disuse, aging, and chronic diseases. Insulin-like growth factor-1 (IGF-1) signaling stimulates muscle growth and suppresses muscle protein breakdown. In atrophied muscles, ubiquitin ligase, Cbl-b, increases and stimulates the ubiquitination and degradation of IRS-1, an intermediate in IGF-1 signaling pathway, resulting in IGF-1 resistance. In this study, we evaluated the efficacy of atelocollagen (ATCOL)-transported anti-ubiquitination oligopeptide (Cblin: Cbl-b inhibitor) (consisting of tyrosine phosphorylation domain of IRS-1) in starved C2C12 myotubes. The amount of IRS-1 protein was lower in starved versus unstarved myotubes. The Cblin-ATCOL complex inhibited IRS-1 degradation in a concentration-dependent manner. Myotubes incubated with Cblin-ATCOL complex showed significant resistance to starvation-induced atrophy (p<0.01). Furthermore, the Cblin-ATCOL complex significantly inhibited any decrease in Akt phosphorylation (p<0.01) and localization of FOXO3a to the nucleus in starved myotubes. These results suggest that Cblin prevented starvation-induced C2C12 myotube atrophy by maintaining the IGF-1/Akt/FOXO signaling. Therefore, attachment of anti-ubiquitination oligopeptide, Cblin, to ATCOL enhances its delivery to myotubes and could be a potentially effective strategy in the treatment of atrophic myopathies.

Stress relaxation behaviors of articular cartilages in porcine temporomandibular joint.

In this study, we tested the compressive stress relaxation behaviors of the mandibular condylar and temporal cartilages in the porcine temporomandibular joint (TMJ). The aim was to determine the quantitative and qualitative similarities and differences of compressive stress relaxation behaviors between the two cartilages. Ten porcine TMJs were used; the articular surface was divided into 5 regions: anterior, central, posterior, lateral and medial. Compressive relaxation test was carried out at a strain level of 5% in each region of the two cartilages. The stress relaxation was monitored over a period of 5min. In all the regions of the two cartilages, the time-dependent stress relaxation curves showed a marked drop in stress within the initial 10s, which can be fitted by a standard linear viscoelastic model. The instantaneous moduli in the temporal cartilage were dominantly larger than those in the condylar cartilage, while the condylar cartilage had slightly larger relaxation moduli than the temporal cartilage except for the medial region. The both cartilages showed the regional differences in the compressive stress relaxation behavior, and in the temporal cartilage the lateral and medial regions revealed the largest values for the instantaneous and relaxation moduli. The present results demonstrate that the viscoelastic properties of compressive stress relaxation in both cartilages are region-specific, which might have an important implication for stress distribution and transmission along with the TMJ disc.

Effectiveness of cationic liposome-mediated local delivery of myostatin-targeting small interfering RNA in vivo.

This study evaluated the effectiveness of local administration of cationic liposome-delivered myostatin-targeting siRNA. Myostatin (Mst)-siRNA and scrambled (scr)-siRNA-lipoplexes were injected into the masseter muscles of wild type and dystrophin-deficient mdx mice, which model Duchenne muscular dystrophy. One week after injection, the masseter muscles were dissected for histometric analyses. To evaluate changes in masseter muscle activity, masseter electromyographic (EMG) measurements were performed. One week after local administration of Mst-siRNA-lipoplexes, masseter muscles and myofibrils were significantly larger compared to control masseter muscles treated with scr-siRNA-lipoplexes. Real-time polymerase chain reaction (PCR) analyses revealed significant upregulation of the myogenic regulatory factors MyoD and myogenin and significant downregulation of the adipogenic transcription factors peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer binding protein-α (CEBPα) in masseter muscles treated with Mst-siRNA-lipoplexes. The duty times of masseter muscle activity exceeding 5% showed a slight tendency to increase in both wild type and mdx mice. Therefore, cationic liposome-mediated local administration of Mst-siRNA could increase muscular size and improve muscle activity. Since cationic liposomes delivered siRNA to muscles effectively and are safe and cost-effective, they may represent a therapeutic tool for use in treating muscular diseases.