Kanaka Yatabe

Incidence of injury among adolescent soccer players: a comparative study of artificial and natural grass turfs

Objective:To investigate the incidence of acute injuries and soccer-related chronic pain from long-term training and during matches in adolescent players using natural grass turfs (NT) and artificial turfs (AT). Design:Case-controlled prospective study. Setting:Institutional-level Fédération Internationale de Football Association Medical Centre of Excellence. Participants:Youth soccer players (12-17 years of age) from 6 teams, with a predominant tendency to train on either NT or AT, were included. Of 332 players enrolled in this study, 301 remained to completion. Interventions:Medically diagnosed acute injuries and chronic pain were recorded daily by team health care staff throughout 2005, and reports were provided monthly to the authors. Assessment of Risk Factors:Noninvasive prospective study. Independent Variables:Age and turf type. Main Outcome Measures:Acute injuries per 1000 player hours on each surface and chronic complaints per 1000 player hours were evaluated according to frequency of surface used ≥80% of the time. Incidence rate ratio (IRR) of acute injuries and chronic complaints during play on NT and AT was calculated. Results:There was no significant difference in the incidence of acute injuries between the 2 surfaces during training and competition. However, the AT group showed a significantly higher incidence of low back pain during training (IRR, 1.62; 95% confidence interval, 1.06-2.48). Early adolescence and prolonged training hours were factors associated with an increased incidence of chronic pain in the AT group. Conclusion:Adolescent players routinely training on AT for prolonged periods should be carefully monitored, even on AT conforming to new standards.

The NAD-Dependent Deacetylase Sirtuin-1 Regulates the Expression of Osteogenic Transcriptional Activator Runt-Related Transcription Factor 2 (Runx2) and Production of Matrix Metalloproteinase (MMP)-13 in Chondrocytes in Osteoarthritis.

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.

The Nicotinamide Adenine Dinucleotide (NAD)-Dependent Deacetylase Sirtuin-1 Regulates Chondrocyte Energy Metabolism through the Modulation of Adenosine Monophosphate-Activated Protein Kinase (AMPK) in Osteoarthritis(OA)

To clarify how the osteoarthritis (OA)-induced catabolic factor interleukin (IL)-1β affects chondrocyte energy metabolism, and especially to define the downstream pathway linking nicotinamide adenine dinucleotide (NAD)- dependent deacetylase Sirtuin-1 (Sirt-1) to energy metabolism in OA chondrocytes. Human chondrocytes were isolated from articular cartilage samples of patients with OA. The level of energy metabolism of OA chondrocytes was evaluated by monitoring the activity of the energy metabolic sensor, adenosine monophosphate-activated protein kinase (AMPK) and the level of production of adenosine triphosphate (ATP) in chondrocytes in the presence or absence of t IL-1β (10 ng/mL). Effects of IL-1β on anabolic and catabolic activities of chondrocytes were analyzed by the levels of production of proteoglycan and matrix metalloproteinase (MMP)-13, respectively. Experiments involving pre-treatment with Sirt-1 inhibitor were also performed to investigate the underlying regulatory mechanism linking Sirt-1 to chondrocyte energy metabolism. IL-1β significantly inhibited the activity of AMPK and production of ATP in OA chondrocytes. The energy metabolism disruption mediated by IL-1β was further decreased by pretreatment with Sirt-1 inhibitor in OA chondrocytes. Treatment with IL-1β significantly decreased the level of proteoglycan production and significantly increased the level of MMP-13 secretion by chondrocytes. These chondrocyte activities were also reduced by pre-treatment with the Sirt-1 inhibitor in OA chondrocytes. IL-1β inhibits the AMPK - ATP energy metabolic pathway in OA chondrocytes. Our findings also suggest that Sirt-1 activity is involved in anabolic and catabolic cellular activities and that Sirt-1 modulates ATP production through functional regulation of the energy sensor AMPK in chondrocytes.

Effects of serotonin transporter gene polymorphism on mood during the period before the competition in Japanese ballet dancers

We investigated whether serotonin transporter gene linked polymorphic region (5-HTTLPR) can predict mood state in Japanese ballet dancers, when they are placed under psychological pressure. Participants were 25 elite student ballet (Elite) dancers with future potential and 19 pro-ballet (Pro) dancers. We administered two psychological questionnaires (STAI: State-Trait Anxiety Inventory; BRUMS: Brunel Mood Scale) to the participants on a typical day and on one of stressful days. The frequency of the 5-HTTLPR genotype in the dancers was as follows: s/s, 64.7%; s/l, 35.3%; l/l, 0%. There was only significant difference in STAI scores on before-competition between s/s and s/l genotypes. In this study, the Trait-Anxiety scores of Elite dancers were significantly higher than those of the Pro dancers (p<0.028). The main effects were significant of genotypes in the BRUMS scores (P<0.035) and of Pro/Elite groups (P<0.002); the 5-HTTLPR has played a certain role in the background of state-trait anxiety, and the psychological test scores were strongly influenced by occupational factors. We can predict the status of BRUMS before the competition by examining the Trait-Anxiety in Elite. Dance level (Elite versus Pro) appears to have far more robust effects on dancer mental status than does 5-HTTLPR genotype.