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Miyamoto Y.,National Health Research Institute | Miyamoto Y.,Japan Human science Foundation | Torii T.,National Health Research Institute | Yamamori N.,National Health Research Institute | And 6 more authors.
Science Signaling | Year: 2013

During neuronal development, axons navigate long distances, eventually forming precise connections with such targets as peripheral tissues. Dock6 is a guanine nucleotide exchange factor (GEF) that activates the Rho family guanosine triphosphatases Rac1 and Cdc42 to regulate the actin cytoskeleton. We found that phosphorylation of Ser1194 in Dock6 inhibited its GEF activity and suppressed axonal growth of embryonic sensory neurons and axon regeneration of postnatal sensory neurons in vitro and in vivo. At early developmental stages, when axons are growing, the protein phosphatase PP2A interacted with and dephosphorylated Dock6, thereby increasing the activity of Dock6. At later developmental stages, the abundance of the kinase Akt increased, resulting in the binding of Akt to Dock6 and the phosphorylation of Dock6 at Ser 1194. In dorsal root ganglion neurons from mice lacking Dock6, reintroduction of Dock6 with a nonphosphorylatable S1194A mutation rescued axon extension but not branch number, whereas reintroduction of Dock6 with a phosphomimetic S1194E mutation resulted in premature branching. Thus, the phosphorylation status of Dock6 at Ser1194 determines whether it promotes axon extension or branching in sensory neurons, revealing interplay between kinase and phosphatase action on a Rho-GEF during axon growth.


Seichi A.,Jichi Medical University | Hoshino Y.,Jichi Medical University | Doi T.,Fukuoka Clinic | Akai M.,National Rehabilitation Center for Persons with Disabilities | And 2 more authors.
Journal of Orthopaedic Science | Year: 2012

Objective To evaluate the reliability and validity of a new questionnaire, the 25-question Geriatric Locomotive Function Scale (GLFS-25), for early detection of locomotive syndrome. Methods This new screening tool was designed to detect Japanese individuals under high-risk conditions who may soon require care services because of problems of the locomotive organs. Content validity, construct validity, criterion validity, internal-consistency reliability, and reproducibility (test-retest reliability) were examined using psychometric analysis, and a cutoff score to detect locomotive syndrome was determined. To investigate construct validity of the GLFS-25 and determine the cutoff score, the Akaike Information Criteria (AIC) were used. Results Study 1 analyzed 711 Japanese elderly people C65 years old. No floor or ceiling effects were included in the GLFS-25. Internal consistency was confirmed by a Cronbach's a reliability coefficient of 0.961. As for the association between the GLFS-25 and European Quality of Life Scale-5 Dimensions (EQ-5D), Spearman's correlation coefficient was 0.85 (P\0.001), showing excellent concurrent validity of the GLFS-25. Categorical principal component analysis showed that the construct structure consisted of one item cluster or the GLFS-25 was unifactorial. The AIC showed that one cluster of seven items was located in the center, with significant associations with the other five clusters. In study 2, 205 individuals were analyzed, and the test-retest interclass correlation was satisfactory (range 0.712-0.924). The cutoff score for identifying locomotive syndrome was set at 16. Validity and reliability of this new measurement were psychometrically confirmed as sufficient. Conclusions The GLFS-25 offers a valid and reliable questionnaire scale for detecting locomotive syndrome in elderly Japanese individuals. © The Japanese Orthopaedic Association 2012.


Nagano Y.,Niigata University of Health and Welfare | Ida H.,Tokyo Institute of Technology | Akai M.,National Rehabilitation Center for Persons with Disabilities | Fukubayashi T.,Waseda University
Journal of Sports Sciences | Year: 2011

Female athletes are considered to exhibit knee and trunk motion that is characteristic of anterior cruciate ligament (ACL) injury. The aim of this study was to examine the in vivo motion of the trunk and knee during a cutting manoeuvre and determine the relationship between them. All participants (10 male and 10 female college athletes) performed a shuttle run cutting task with the left limb. Trunk inclination (forward and lateral) and knee joint angles (flexion/extension, abduction/ adduction, and internal/external tibial rotation) were calculated. Differences between the sexes and associations between knee motion and trunk inclination were examined. An increase in trunk forward inclination was strongly correlated with an increase in knee flexion angle and moderately correlated with a decrease in the excursion of internal tibial rotation. An increase in right trunk lateral inclination was moderately correlated with an increase in excursion of internal tibial rotation. The results also showed differences between the sexes in trunk forward inclination, lateral inclination, and knee flexion angle, but no such differences in knee abduction or internal tibial rotation. Trunk inclination is related to knee flexion and excursion of internal tibial rotation. Female athletes demonstrate a low trunk forward inclination and knee flexion angle, a posture that resembles that of ACL injury. © 2011 Taylor & Francis.


Nagano Y.,Niigata University of Health and Welfare | Ida H.,Tokyo Institute of Technology | Akai M.,National Rehabilitation Center for Persons with Disabilities | Fukubayashi T.,Waseda University
Sports Medicine, Arthroscopy, Rehabilitation, Therapy and Technology | Year: 2011

Background: Some research studies have investigated the effects of anterior cruciate ligament (ACL) injury prevention programs on knee kinematics during landing tasks; however the results were different among the studies. Even though tibial rotation is usually observed at the time of ACL injury, the effects of training programs for knee kinematics in the horizontal plane have not yet been analyzed. The purpose of this study was to determine the effects of a jump and balance training program on knee kinematics including tibial rotation as well as on electromyography of the quadriceps and hamstrings in female athletes.Methods: Eight female basketball athletes participated in the experiment. All subjects performed a single limb landing at three different times: the initial test, five weeks later, and one week after completing training. The jump and balance training program lasted for five weeks. Knee kinematics and simultaneous electromyography of the rectus femoris and Hamstrings before training were compared with those measured after completing the training program.Results: After training, regarding the position of the knee at foot contact, the knee flexion angle for the Post-training trial (mean (SE): 24.4 (2.1) deg) was significantly larger than that for the Pre-training trial (19.3 (2.5) deg) (p < 0.01). The absolute change during landing in knee flexion for the Post-training trial (40.2 (1.9) deg) was significantly larger than that for the Pre-training trial (34.3 (2.5) deg) (p < 0.001). Tibial rotation and the knee varus/valgus angle were not significantly different after training. A significant increase was also found in the activity of the hamstrings 50 ms before foot contact (p < 0.05).Conclusions: The jump and balance training program successfully increased knee flexion and hamstring activity of female athletes during landing, and has the possibility of producing partial effects to avoid the characteristic knee position observed in ACL injury, thereby preventing injury. However, the expected changes in frontal and transverse kinematics of the knee were not observed. © 2011 Nagano et al; licensee BioMed Central Ltd.


Yoshimura N.,Tokyo Medical University | Muraki S.,Tokyo Medical University | Oka H.,Tokyo Medical University | Tanaka S.,University of Tokyo | And 3 more authors.
Osteoarthritis and Cartilage | Year: 2012

Objective: To clarify the association between the occurrence and progression of knee osteoarthritis (KOA) with components of metabolic syndrome (MS), including overweight (OW), hypertension (HT), dyslipidaemia (DL), and impaired glucose tolerance (IGT), in a general population. Design: From the large-scale population-based cohort study entitled Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) initiated in 2005, 1,690 participants (596 men, 1,094 women) residing in mountainous and coastal areas were enrolled. Of these, 1,384 individuals (81.9%; 466 men, 918 women) completed the second survey, including knee radiography, 3 years later. KOA was defined as Kellgren-Lawrence (KL) grade ≥ 2 using paired X-ray films. Based on changes in KL grades between the baseline and second surveys, cumulative incidence and progression of KOA were determined. OW, HT, DL, and IGT at baseline were assessed using standard criteria. Results: The cumulative incidence of KOA among 1,384 completers over 3 years was 3.3%/year, and progression in KL grades for either knee, 8.0%/year. Logistic regression analyses after adjusting for potential risk factors revealed that the odds ratio (OR) for the occurrence of KOA significantly increased according to the number of MS components present (OR vs no component: one component, 2.33; two components, 2.82; ≥three components, 9.83). Similarly, progression of KOA significantly increased according to the number of MS components present (OR vs no component: one component, 1.38; two components, 2.29; ≥three components: 2.80). Conclusion: Accumulation of MS components is significantly related to both occurrence and progression of KOA. MS prevention may be useful in reducing future KOA risk. © 2012 Osteoarthritis Research Society International.


Akune T.,University of Tokyo | Muraki S.,University of Tokyo | Oka H.,University of Tokyo | Tanaka S.,University of Tokyo | And 3 more authors.
Osteoporosis International | Year: 2014

The present cross-sectional study investigated the prevalence of sarcopenia and clarified its associated factors in 1,000 elderly participants of Japanese population-based cohorts. Exercise habit in middle age was associated with low prevalence of sarcopenia in older age, suggesting that it is a protective factor against sarcopenia in older age. Introduction: The present study investigated the prevalence of sarcopenia using the European Working Group on Sarcopenia in Older People (EWGSOP) definition, and clarified the association of sarcopenia with physical performance in the elderly participants of Japanese population-based cohorts of the Research on Osteoarthritis/osteoporosis Against Disability (ROAD) study. Methods: We enrolled 1,000 participants (aged ≥65 years) from the second visit of the ROAD study who had completed assessment of handgrip strength, gait speed, and skeletal muscle mass measured by bioimpedance analysis. Presence of sarcopenia was determined according to the EWGSOP algorithm. Information collected included exercise habits in middle age. Results: Prevalence of sarcopenia was 13.8 % in men and 12.4 % in women, and tended to be significantly higher according to increasing age in both sexes. Factors associated with sarcopenia, as determined by logistic regression analysis, were chair stand time (odds ratio [OR], 1.09; 95 % confidence interval [CI], 1.04-1.14), one-leg standing time (OR, 0.97; 95 % CI, 0.96-0.99), and exercise habit in middle age (OR, 0.53; 95 % CI, 0.31-0.90). Exercise habit in middle age was associated with low prevalence of sarcopenia in older age. Furthermore, linear regression analysis revealed that exercise habits in middle age were significantly associated with grip strength (P <.001), gait speed (P <.001), and one-leg standing time (P =.005) in older age. Conclusions: This cross-sectional study suggests that exercise habit in middle age is a protective factor against sarcopenia in older age and effective in maintaining muscle strength and physical performance in older age. © 2013 International Osteoporosis Foundation and National Osteoporosis Foundation.


Seki Y.,Japan National Institute of Advanced Industrial Science and Technology | Sato T.,National Rehabilitation Center for Persons with Disabilities
IEEE Transactions on Neural Systems and Rehabilitation Engineering | Year: 2011

A new auditory orientation training system was developed for blind people using acoustic virtual reality (VR) based on a head-related transfer function (HRTF) simulation. The present training system can reproduce a virtual training environment for orientation and mobility (O&M) instruction, and the trainee can walk through the virtual training environment safely by listening to sounds such as vehicles, stores, ambient noise, etc., three-dimensionally through headphones. The system can reproduce not only sound sources but also sound reflection and insulation, so that the trainee can learn both sound location and obstacle perception skills. The virtual training environment is described in extensible markup language (XML), and the O&M instructor can edit it easily according to the training curriculum. Evaluation experiments were conducted to test the efficiency of some features of the system. Thirty subjects who had not acquired O&M skills attended the experiments. The subjects were separated into three groups: a no-training group, a virtual-training group using the present system, and a real-training group in real environments. The results suggested that virtual-training can reduce veering more than real-training and also can reduce stress as much as real training. The subjective technical and anxiety scores also improved. © 2010 IEEE.


Urakami Y.,National Rehabilitation Center for Persons with Disabilities
Clinical EEG and Neuroscience | Year: 2012

Few methods can predict the prognosis and outcome of traumatic brain injury. Electroencephalographic (EEG) examinations have prognostic significance in the acute stage of posttraumatic coma, and some EEG variables have been correlated with outcome. Furthermore, spindle activity and reactivity in the acute stage have been associated with good recovery. Assessments of consciousness based on EEG and magnetoencephalographic (MEG) recordings provide valuable information for evaluating residual function, forming differential diagnoses and estimating prognosis. This study objectively investigated how fast spindles could relate to the recovery of consciousness and cognitive function during the post-acute to chronic stages of diffuse axonal injuries (DAIs). Sleep stage 2 was examined in 7 healthy participants and 8 patients with DAIs. Simultaneous EEG and MEG recordings were performed in the post-acute (mean 80 days) and chronic (mean 151 days) stages of recovery. Magnetoencephalography enabled equivalent current dipole estimates of fast spindle sources. Clinical recovery was evaluated by consciousness, neuropsychological examination, and outcome. Six severe and two moderate injuries were studied in patients with favorable 1-year outcomes. In the sub-acute stage, significant decreases were detected in the frequency, amplitude, and cortical activation source strengths of spindle activities, but these recovered during the chronic stage. In the chronic stage, the Wechsler adult intelligence factor scale and subset patterning revealed significant improvement in cognitive function. These results suggested that spindles may reflect recovery of consciousness and cognitive function following a DAI. © 2012 EEG and Clinical Neuroscience Society.


Akune T.,National Rehabilitation Center for Persons with Disabilities
Clinical Reviews in Bone and Mineral Metabolism | Year: 2016

Locomotive syndrome refers to conditions under which the elderly have been receiving support or long-term care, or high-risk conditions under which they might soon require support or long-term care, which are caused by musculoskeletal disorders. The concept of locomotive syndrome was proposed by the Japanese Orthopedic Association in 2007 for the promotion of preventive health care of locomotive organs to reduce its risk and decrease the number of disabled elderly requiring care in their activities of daily living. Sarcopenia is among the causes of locomotive syndrome since it is characterized by generalized loss of skeletal muscle mass and muscle strength or function and is associated with physical disability and poor quality of life. Consensus definition of sarcopenia was provided by the European Working Group on Sarcopenia in Older People (EWGSOP) and the International Working Group on Sarcopenia (IWGS). Prevalence of sarcopenia defined by the EWGSOP or the IWGS criteria and its associated factors have been reported in many studies. It might be difficult for people to recognize functional declines in locomotive organs, including muscle strength and physical performance, since they usually progress slowly and gradually. Therefore, it is of particular importance to raise awareness of the growing risk and to take action to improve and maintain the health of locomotive organs for prevention of sarcopenia and other diseases in locomotive syndrome. © 2016, Springer Science+Business Media New York.


News Article | October 26, 2016
Site: www.newscientist.com

It’s a tale of two tails. Mice can be tricked into thinking fake tails are their own, using the same “rubber hand illusion” that works in people. The illusion helps us understand how our brains create a sense of body ownership and awareness. The discovery that mice fall for the same trick could aid the development of prosthetic limbs and treatments for psychiatric disorders. In the human version of the trick, a person sits next to a rubber hand and their own hand is hidden. Stroking both hands at the same time tricks the person into feeling that the rubber limb is their own. When the fake hand is attacked, people yell out in fear – as if their own limb were under threat. Kenji Kansaku at the National Rehabilitation Center for Persons with Disabilities in Tokorozawa, Japan, and his colleagues performed the same trick on mice, hiding their tails and using a fake one. When the fake and real tails were stroked out of sync, the mice didn’t react to the fake tails being approached. But when their own tail was stroked simultaneously with the fake one, they reacted strongly, twisting as if to pull the fake tail away. Henrik Ehrsson at the Karolinska Institute in Stockholm, Sweden, was surprised by the result. In people, a brain region called the parietal association cortex is important for body ownership. This region is tiny in mouse brains, he says. Studying the activity of various brain cells in mice during the illusion – something you can’t do in humans – could offer plenty of insights, says Ehrsson. For example, knowing the precise brain activity involved could shed light on disorders in which body awareness is disrupted, such as schizophrenia, and help with the development of prosthetic limbs that are more easily incorporated into body image.

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