Aging is one of the major pathologic factors associated with osteoarthritis (OA). Recently, numerous reports have demonstrated the impact of sirtuin-1 (Sirt1), which is the NAD-dependent deacetylase, on human aging. It has been demonstrated that Sirt1 induces osteogenic and chondrogenic differentiation of mesenchymal stem cells. However, the role of Sirt1 in the OA chondrocytes still remains unknown. We postulated that Sirt1 regulates a hypertrophic chondrocyte lineage and degeneration of articular cartilage through the activation of osteogenic transcriptional activator Runx2 and matrix metalloproteinase (MMP)-13 in OA chondrocytes. To verify whether sirtuin-1 (Sirt1) regulates chondrocyte activity in OA, we studied expressions of Sirt1, Runx2 and production of MMP-13, and their associations in human OA chondrocytes. The expression of Sirt1 was ubiquitously observed in osteoarthritic chondrocytes; in contrast, Runx2 expressed in the osteophyte region in patients with OA and OA model mice. OA relating catabolic factor IL-1βincreased the expression of Runx2 in OA chondrocytes. OA chondrocytes, which were pretreated with Sirt1 inhibitor, inhibited the IL-1β-induced expression of Runx2 compared to the control. Since the Runx2 is a promotor of MMP-13 expression, Sirt1 inactivation may inhibit the Runx2 expression and the resultant down-regulation of MMP-13 production in chondrocytes. Our findings suggest thatSirt1 may regulate the expression of Runx2, which is the osteogenic transcription factor, and the production of MMP-13 from chondrocytes in OA. Since Sirt1 activity is known to be affected by several stresses, including inflammation and oxidative stress, as well as aging, SIRT may be involved in the development of OA.

Mechanical stress is an important factor affecting bone tissue homeostasis. We focused on the interactions among mechanical stress, glucose uptake via glucose transporter 1 (Glut1), and the cellular energy sensor sirtuin 1 (SIRT1) in osteoblast energy metabolism, since it has been recognized that SIRT1, an NAD+-dependent deacetylase, may function as a master regulator of the mechanical stress response as well as of cellular energy metabolism (glucose metabolism). In addition, it has already been demonstrated that SIRT1 regulates the activity of the osteogenic transcription factor runt-related transcription factor 2 (Runx2). The effects of mechanical loading on cellular activities and the expressions of Glut1, SIRT1, and Runx2 were evaluated in osteoblasts and chondrocytes in a 3D cell–collagen sponge construct. Compressive mechanical loading increased osteoblast activity. Mechanical loading also significantly increased the expression of Glut1, significantly decreased the expression of SIRT1, and significantly increased the expression of Runx2 in osteoblasts in comparison with non-loaded osteoblasts. Incubation with a Glut1 inhibitor blocked mechanical stress-induced changes in SIRT1 and Runx2 in osteoblasts. In contrast with osteoblasts, the expressions of Glut1, SIRT1, and Runx2 in chondrocytes were not affected by loading. Our present study indicated that mechanical stress induced the upregulation of Glut1 following the downregulation of SIRT1 and the upregulation of Runx2 in osteoblasts but not in chondrocytes. Since SIRT1 is known to negatively regulate Runx2 activity, a mechanical stress-induced downregulation of SIRT1 may lead to the upregulation of Runx2, resulting in osteoblast differentiation. Incubation with a Glut1 inhibitor the blocked mechanical stress-induced downregulation of SIRT1 following the upregulation of Runx2, suggesting that Glut1 is necessary to mediate the responses of SIRT1 and Runx2 to mechanical loading in osteoblasts.

Exercise increases oxidative stress, leading the body to strengthen its antioxidant defenses, thus reducing the incidence of major diseases. As these associations are relatively unclear for ordinary levels of exercise for reduced stress, this study evaluated the effects of different exercise conditions on diacron-reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and subjective mood. Forty-nine students (22.4 ± 2.6 years) were assessed using the Profile of Mood States (POMS) before and after exercising for 60 min. Participants were divided into two groups: Group A engaged in compulsory sports and Group B in freely chosen sports. d-ROMs and BAP were measured, and their modified ratio was calculated as an index of antioxidant potential. Physiological evaluation showed significant improvements in BAP and the BAP/d-ROMs ratio, irrespective of exercise condition (p < 0.001, p < 0.01). Comparison between the exercise conditions revealed a significant difference in the modified ratio (p < 0.02). In mood assessment, scores on emotion-related scales without vigor improved significantly under both exercise conditions (p < 0.001). Mental changes were evident after exercise, and potential antioxidant capacity was higher in freely chosen sports (p < 0.03). Assessment of antioxidant status before and after exercise may provide an objective index of mental and physical conditioning.

We investigated, in an animal model of skeletal muscle injury, whether microcurrent electrical neuromuscular stimulation (MENS) and hyperbaric oxygen (HBO) therapy used in combination (MENS and HBO) enhances the restorative benefits conferred by these treatments alone. Skeletal muscle injury was simulated in 40 7-week-old male C57BL/6J mice by injection of cardiotoxin (CTX) into the left tibialis anterior (TA) muscle of each mouse, which induced the necrosis-regeneration cycle. The mice were divided into 4 groups of 10 each and subjected to one of the following no additional treatment (X), HBO (XH), MENS (XM), MENS and HBO (XMH) groups. MENS was delivered at 10 µA intensity, 0.3 Hz frequency, and 250 msec pulse width for 60 minutes per day, 3 days per week for 2 weeks, and HBO was performed with 100% oxygen at 2 atmospheres absolute (ATA) for 60 minutes per day, 3 days per week for 2 weeks. One and 2 weeks after CTX injection, the TA muscle was dissected. Two weeks after CTX injection, both the mean fiber cross-sectional area (CSA) and percentage increase in the fiber CSA were significantly greater in the XMH group than in the X group (P <0.05). The fiber CSA increased without treatment and also under sole treatment with either MENS or HBO, but the values did not differ significantly. Our data indicate that combination MENS and HBO therapy enhances regeneration of injured skeletal muscle and that such combination therapy may be clinically beneficial.

Introduction: Professional dancers are committed to dancing despite their injuries and mood changes. Therefore, dancers’ balance ability should be evaluated as an objective indicator of the quality of their dance/dancing ability.Objective: We aimed to examine the relationship between the balance ability of professional ballet dancers and their psychological traits and states by serotonin polymorphism, using pressure and center of gravity sensors.Methods: Five female professional dancers participated in this three-month longitudinal pilot study. The dancers’ stress status was assessed each month on three conditional days to gauge stress conditions. Before and after their standard warm-up exercises, the dancers’ center of gravity was assessed while standing and posing in ballet-specific positions, and psychological questionnaire surveys were conducted to assess the level of anxiety and objective stress. After all observations were completed, serotonin polymorphism was analyzed as one of the psychological traits.Results: All participants possessed the s/s-type (short type) serotonin transporter gene promoter polymorphism, indicating high sensitivity to stress. Their average trait anxiety score was 50.80±8.47. However, all participants were able to be calm, had no injuries, and maintained a stable center of gravity throughout the study period.Conclusion: Throughout the study, from ordinary practice to the time of the approaching ballet performance, the participants maintained stable balance ability regardless of their psychological traits and states of mind. It is unlikely that reactions to stress and psychological traits affected professional dancers’ physicality. Thus, continuous assessment of the balance between mental and physical aspects enhances performance management.