Hideki Kataoka

Low‐level laser irradiation promotes the recovery of atrophied gastrocnemius skeletal muscle in rats

Low‐level laser (LLL) irradiation promotes proliferation of muscle satellite cells, angiogenesis and expression of growth factors. Satellite cells, angiogenesis and growth factors play important roles in the regeneration of muscle. The objective of this study was to examine the effect of LLL irradiation on rat gastrocnemius muscle recovering from disuse muscle atrophy. Eight‐week‐old rats were subjected to hindlimb suspension for 2 weeks, after which they were released and recovered. During the recovery period, rats underwent daily LLL irradiation (Ga–Al–As laser; 830 nm; 60 mW; total, 180 s) to the right gastrocnemius muscle through the skin. The untreated left gastrocnemius muscle served as the control. In conjunction with LLL irradiation, 5‐bromo‐2′‐deoxyuridine (BrdU) was injected subcutaneously to label the nuclei of proliferating cells. After 2 weeks, myofibre diameters of irradiated muscle increased in comparison with those of untreated muscle, but did not recover back to normal levels. Additionally, in the superficial region of the irradiated muscle, the number of capillaries and fibroblast growth factor levels exhibited significant elevation relative to those of untreated muscle. In the deep region of irradiated muscle, BrdU‐positive nuclei of satellite cells and/or myofibres increased significantly relative to those of the untreated muscle. The results of this study suggest that LLL irradiation can promote recovery from disuse muscle atrophy in association with proliferation of satellite cells and angiogenesis.

Effects of Therapeutic Ultrasound on Joint Mobility and Collagen Fibril Arrangement in the Endomysium of Immobilized Rat Soleus Muscle

This study examined effects of therapeutic ultrasound on joint mobility and collagen fibril arrangement in the endomysium of immobilized rat soleus muscle. Twenty-two male Wistar rats were divided randomly into control (n = 5) and experimental groups (n = 17). In the experimental group, bilateral ankle joints of each rat were fixed in full plantar flexion with a plaster cast over a 4-wk period. Five animals in the experimental group were immobilized throughout the 4-wk (immobilization group) period, whereas the remaining rats in the experimental group were randomly divided into the ultrasound (US, n = 6) and sham (n = 6) treatment groups. Under anesthesia, continuous ultrasonic energy (frequency, 1 MHz; intensity, 1.0 W/cm(2)) was delivered to the triceps surae muscle of the US group for 15 min per d, 6 d per wk over the 4-wk immobilization period. Ultrasonic energy was not delivered to the triceps surae muscle in sham animals; only the transducer head was moved. Ankle joint mobility on dorsiflexion in the immobilization, sham and US groups was significantly smaller than that of the control group, whereas in the US group, this parameter was significantly greater than in the immobilization and sham groups. Collagen fibril arrangement in the endomysium of the control and US groups was longitudinal to the axis of the muscle fibers; in contrast, it was circumferential in the immobilization and sham groups. Our findings revealed that joint immobilization induces decreased joint mobility and collagen fibril movement in the endomysium; furthermore, ultrasound treatment can prevent these changes. We hypothesized that therapeutic ultrasound during the immobilization process may inhibit deterioration of muscle contracture.

Upregulation of interleukin-1β/transforming growth factor-β1 and hypoxia relate to molecular mechanisms underlying immobilization-induced muscle contracture.

Introduction: In this study we investigated the molecular mechanism underlying muscle contracture in rats. Methods: The rats were divided into immobilization and control groups, and soleus muscles of the right and left sides were selected for analyses. Results: The levels of CD11b and α‐SMA protein, IL‐1β, and TGF‐β1 mRNA, and type I and III collagen protein and mRNA were significantly greater in the immobilization group than in the control group at all time‐points. HIF‐1α mRNA levels were significantly higher in the immobilization group at 4 weeks. Moreover, HIF‐1α, α‐SMA, and type I collagen levels were significantly higher at 4 weeks than at 1 and 2 weeks in the immobilization group. Conclusions: In the early stages of immobilization, upregulation of IL‐1β/TGF‐β1 via macrophages may promote fibroblast differentiation that could affect muscle contracture. The soleus muscle became hypoxic in the later stages of immobilization, suggesting that hypoxia influences the progression of muscle contracture. Muscle Nerve 52:419–427, 2015

Effects of joint immobilization on changes in myofibroblasts and collagen in the rat knee contracture model

The purpose of this study was to examine the time‐dependent changes in the development of joint capsule fibrosis and in the number of myofibroblasts in the joint capsule after immobilization, using a rat knee contracture model. Both knee joints were fixed in full flexion for 1, 2, and 4 weeks (immobilization group). Untreated rats were bred for each immobilization period (control group). Histological analysis was performed to evaluate changes in the amount and density of collagen in the joint capsule. The changes in type I and III collagen mRNA were examined by in situ hybridization. The number of myofibroblasts in the joint capsule was assessed by immunohistochemical methods. In the immobilization group, the amount of collagen increased within 1 week and the density of collagen increased within 2 weeks, as compared with that in the control group. Type I collagen mRNA‐positive cell numbers in the immobilization group increased at all time points. However, type III collagen mRNA‐positive cell numbers did not increase. Myofibroblasts in the immobilization group significantly increased compared with those in the control group at all time points, and they increased significantly with the period of immobilization. These results suggest that joint capsule fibrosis with overexpression of type I collagen occurs and progresses within 1 week after immobilization, and an increase in myofibroblasts is related to the mechanism of joint capsule fibrosis. The findings suggest the need for a treatment targeting accumulation of type I collagen associated with an increase in myofibroblasts.

Factors associated with chronic musculoskeletal pain in Japanese community-dwelling older adults: A cross-sectional study

Abstract Identifying older adults with chronic musculoskeletal pain (CMP) earlier is urgent because CMP is reportedly associated with deterioration in physical function, poor psychological status, and low physical activity level. The objective of this study was to identify factors that were most strongly associated with CMP in Japanese community-dwelling older adults. Using a cross-sectional design, we assessed 263 older adults (mean age = 79.1 ± 5.9 years, 85.9% women) who participated in community exercise classes. Participants’ physical function, psychological status, and activity levels were evaluated as outcome measures using a variety of tests and instruments. These assessments were conducted prior to beginning the exercise intervention program and compared participants with and without CMP. Additionally, relevant participant characteristics were collected and analyzed. In this study, CMP was defined as the presence of related symptoms within the past month that continued for at least 6 months and corresponded to a numerical rating scale of at least 5 or more at the site of maximum pain. A total of 143 (54.4%) participants met the criteria for CMP, and a high number of them had chronic lower back pain (64.3%). Outcome measures for the CMP group were significantly worse than for the non-CMP group (P < .05). Logistic regression analysis revealed that the Pain Catastrophizing Scale helplessness domain scores (odds ratio: 1.20, 95% confidence interval: 1.09–1.32) with an estimated value of 10 points was the factor most significantly associated with the presence of CMP. These findings suggest that assessment of the helplessness associated with pain-related catastrophizing is important for identification and the creation of interventions for older adults with CMP.

Effects of a psychosocial intervention programme combined with exercise in community-dwelling older adults with chronic pain: A randomized controlled trial

Although researchers have recommended exercise training and psychosocial intervention to manage chronic pain, an effective intervention for Japanese community‐dwelling older adults with chronic pain has not been established. This randomized controlled trial examined whether exercise training combined with psychosocial intervention more effectively improves pain, psychological status and physical activity than does exercise training alone in this population.

Prediction of prognosis of upper-extremity function following stroke-related paralysis using brain imaging

[Purpose] Diffusion tensor imaging (DTI) has attracted attention as a method for determining prognosis following paralysis after stroke. However, DTI can assess the degree of damage to the corticospinal tract but cannot evaluate other brain regions. In this study, we examined in detail the prognosis of upper-limb function of the paralyzed side following stroke, using DTI and voxel-based morphometry (VBM). [Subjects and Methods] We studied 17 consecutive patients diagnosed with stroke, including hemorrhagic and ischemic types, who exhibited hemiparesis and were treated in our hospital. DTI and VBM were performed 14 days after admission. Outcome measurements that assessed upper limb function were Fugl-Meyer Assessment (FMA) and Motor Activity Log (MAL), which were applied after 3 months. [Results] The fractional anisotropy ratio of the bilateral cerebral peduncles (rFA) was significantly correlated with FMA, amount of use, and quality of movement 3 months after stroke. The precentral gyrus significantly degenerated as compared with the control group for a case with notable motor paralysis, for which rFA was high. [Conclusion] We suggest it may be possible to predict recovery of upper limb function following stroke by combining DTI and VBM visualization methods.

Effects of Exercise Training Combined with Increased Physical Activity to Prevent Chronic Pain in Community-Dwelling Older Adults: A Preliminary Randomized Controlled Trial

Objective With the aim of developing a chronic pain prevention program, this randomized controlled trial examined whether exercise training combined with increased physical activity more effectively improves pain and physical activity than exercise training alone in community-dwelling older adults without chronic pain. Methods We randomized 76 older adults without chronic pain into an intervention group (n=38) involving exercise training combined with increased physical activity and a control group (n=38) involving exercise training alone. The exercise training comprised weekly 60-min sessions for 12 weeks. The program to increase physical activity required participants to record their daily step counts using pedometers. Pain intensity, total number of pain sites, and physical activity were assessed before and 12 weeks after the intervention. Results A time-by-group interaction was found for physical activity, with the intervention group showing significant improvement (p < 0.05). The intervention group also showed greater improvement in pain intensity and total number of pain sites at 12 weeks after intervention than the control group (p < 0.05). Conclusions In older adults without chronic pain, exercise training combind with increased physical activity improves key outcome indicators more effectively than exercise training alone. “This trial is registered with UMIN000018503.”

Relationship between extensibility and collagen expression in immobilized rat skeletal muscle: Relationship between Extensibility and Collagen Expression

This study investigated longitudinal changes in muscle extension and collagen expression in an immobilized rat soleus muscle, and assessed the relationship between both elements.

Impact of frailty on chronic pain, activities of daily living and physical activity in community-dwelling older adults: A cross-sectional study: Frailty and chronic pain

The present cross‐sectional study investigated the relationship between frailty and chronic pain, activities of daily living (ADL), and physical activity in community‐dwelling older adults.