Osamu Yoshimura’s research while affiliated with Hiroshima City Hospital and other places

As tooth loss has been suggested as a potential risk factor for stroke, oral examinations were carried out on stroke patients to review the oral condition of those patients. The subjects were patients consecutively discharged from the recovery rehabilitation unit of Hiroshima City General Rehabilitation Center between April 2008 and December 2009. All patients were offered oral examination and 358 of 443 patients accepted. Patients receiving dental examination were divided into two groups: one group comprising stroke patients and the second, patients with other disorders. These two groups were then compared for the number of remaining teeth by age group. Among the examined patients, the number of remaining teeth in stroke patients in their 50s and 60s was significantly lower than for patients in corresponding age groups (18.4 ± 9.4 vs. 24.5 ± 5.4 and 18.3 ± 9.2 vs. 22.2 ± 7.2, respectively, with p < 0.05 for both age groups) who were hospitalised for other conditions. In addition, the number of remaining teeth in stroke patients in their 50s was also significantly lower than the number reported in the Survey of Dental Diseases (24.1 ± 6.1; p < 0.05). The results of this study suggest an association between tooth loss and early occurrence of stroke.

It is widely accepted that daily exercise improves the dynamic standing balance of elderly persons. In the current study, 77 community-dwelling Japanese elderly persons (aged 71.1 +/- 0.5 years) participated in a daily exercise program to assess its effect on their dynamic standing balance. The daily exercise consisted of walking, stretching, muscle strengthening, and balance exercises. The program ran for 31 months and the dynamic standing balance was assessed at the start of the program and again at 3, 7, 12, 19, 24, and 31 months. In most of the tests of dynamic standing balance, the measured values improved drastically in the first 7 months; thereafter, they either reached a plateau or continued to improve more slowly. These findings can contribute to the future planning of community-based exercise programs; in particular, the length of the program and the timing of changes to the exercise load.

Reflecting the rapidly aging population, community-based interventions in the form of physical exercise have been introduced to promote the health of elderly persons and prevent falls. Postural response is the critical neural response for preventing falls. The objective of this study was to assess the effect of long-term daily exercise on neural adjustment in postural response elucidated by sudden postural perturbation. Twenty-six community-based elderly persons (13 men and women; 69.8+/-0.5 years old) participated in this study. Daily exercise was composed of walking for longer than 30 min, stretching, muscle strengthening and balance exercise, and was continued for 3 months. Postural responses were induced by fore or aft horizontal displacement of a platform with a force plate. Center of pressure on the force plate and electromyography of the rectus femoris, tibia anterior, biceps femoris and gastrocnemius were measured in postural response. Following the 3 months of physical intervention, the amplitude and timing of the center of pressure excursion did not change, whereas the amplitude of muscular activities of the lower leg muscles required for the response significantly decreased. Furthermore, the onset of muscular activation of the lower leg muscles was significantly shortened following the intervention. In conclusion, we showed that a program composed of 3 months of comprehensive exercise modulated the output of the postural response through a neural adjustment in the timing and amplitude of the muscular activation.

Experimental, controlled trial, animal study.Objective:To assess morphologic changes in different cartilage plates after spinal cord injury and identify the localization of these alterations. Saitama, Japan. A total of 16 Wistar rats were used. Eight rats underwent a spinal cord injury and eight rats had no intervention as control. The cartilage alterations of the knee joint were evaluated with radiography and histomorphometric analysis. To quantify cartilage alterations, we selected the histologic characteristics: thickness of the articular cartilage, number of chondrocytes, matrix staining to toluidine blue as a reflection of proteoglycan content and surface irregularity. No differences in knee joints were found between the groups by radiography. In the medial knee joint, cartilage thickness of spinal-cord-injured knees increased at the anterior femoral region and decreased at the tibial and posterior femoral regions; however, in the lateral knee, that of spinal cord injuries did not change compared with control knees. Spinal cord injuries decreased the number of chondrocytes, especially at the anterior femoral regions. Matrix staining increased partially at the tibial regions. Surface irregularity of spinal-cord-injured knees was comparable to that of control knees in all cartilage plates. The present findings exhibit characteristics of the cartilage after spinal cord injury. These alterations were different in nature between the medial and lateral regions. Future studies should assess separately different cartilage plates, to overestimate these severities when the changes at the medial knee were examined and to underestimate when the changes at the lateral knee were examined.

The objective of this study was to assess the effect of comprehensive exercise program widely accepted as a community-based physical intervention for the prevention of falling in the elderly persons on their controlling standing balance. Twenty-six community-dwelling elderly persons (13 males and females; 69.8 ± 2.8 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise without exercise equipments. The intervention was continued for three months. Indicators of standing balance related to static balance, dynamic balance and postural response were measured before and after the intervention. As an effect of the intervention on static balance, the sway of center of pressure (COP) in the static stance significantly increased. In the dynamic balance, significant improvements were observed in one leg standing time, the 10-m gait time, functional reach. Additionally, the maximal movable length of COP which subjects can move voluntarily to right and left significantly increased. In the postural response, the integrated electromyography (IEMG) induced by postural response for sudden postural perturbation significantly decreased in the lower leg muscles. Since less muscular activities were sufficient to maintain posture, it was suggested that postural response was elicited more efficiently following the intervention. This study suggested that the comprehensive exercise program, which has been widely introduced as community-based interventions for the prevention of falling, have extensive effects on the control of standing balance covering static balance, dynamic balance and postural response in the elderly persons.

Mechanical forces are crucial for the maintenance of the morphologic and functional integrity of articular cartilage. The alteration of the articular cartilage after spinal cord injury (SCI) has been described in relation to a suppression of mechanical forces, since the joint is unloaded and restricted in movement. However, the morphological and biochemical characteristics of the cartilage after SCI are still poorly understood. We identified the localization of cartilage alterations after SCI and verified the influence of mechanical forces on the articular cartilage. A total of 32 Wistar rats were used. Sixteen animals underwent an SCI and 16 animals served as control. The articular cartilage of the knee joint was assessed, respectively, at 4, 8, 10, and 12 weeks after intervention by histochemical, histomorphometric, immunohistochemical, and biochemical analyses. Cartilage thickness of spinal cord-injured knees decreased at the tibial and posterior femoral (FP) regions and increased at the anterior femoral (FA) region. Spinal cord injuries decreased the number of chondrocytes at the anterior regions and decreased the cartilage matrix staining only at the tibial regions. Immunolabeling to collagen type II was noted comparably in the superficial layer but noted weakly from the middle to deep layer. Collagen type I existed excessively at the cartilage surface and the pericellular regions. Cartilage alterations after SCI would not be explained by only a suppression of mechanical forces by unloading and immobilization, but there may be influences on the cartilage in addition to the change in mechanical forces.

Skeletal muscles are a target for motoneurons and synthesize neurotrophins, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5). Both at the embryonic stage and the adult stage, the mRNA expression of neurotrophins in skeletal muscles of rats has been reported. However, little was known about the mRNA expression patterns of neurotrophins in skeletal muscles of rats at the young developmental stage. In this study, we investigated the mRNA expressions of BDNF and NT-3 in three different skeletal muscles in 4- to 8- week-old rats using the reverse transcriptional polymerase chain reaction (RT-PCR) method. The expression of BDNF mRNA in the soleus muscle gradually became higher with age from 5 to 8 weeks. But BDNF mRNA in the tibialis anterior and extensor digitorum longus muscles did not change with growth. The expression of NT-3 mRNA did not show a specific tendency during this period. The differences of muscle fiber types, recruitment patterns of the muscles, and roles of neurotrophins may cause these mRNA expression patterns. Neurotrophins are target-derived, activity-dependent neurotrophic factors and are transported retrogradely. There is a possibility that the different expression patterns of neurotrophins in muscles may be involved in the maturation of neuromuscular function in different muscles during the young developmental period.