Hiroto Fujiya

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.

Functional Overloading Facilitates the Regeneration of Injured Soleus Muscles in Mice

The effect of functional overloading on the regenerating process of injured skeletal muscle was investigated in 10-week-old male mice (C57BL/6J). Functional overloading on soleus of both hindlimbs was performed by cutting the distal tendons of plantaris and gastrocnemius muscles for 2 weeks before cardiotoxin (CTX) injection as the preconditioning and also during 10 weeks of recovery. To activate the necrosis-regeneration cycle, 0.1 ml of 10-microM CTX was injected into soleus muscle. The mean values of absolute muscle weight and the percentage of Pax7-positive nuclei in soleus were increased by the preconditioning. These values, as well as total muscle protein content, in the group with CTX injection plus overloading were larger than in the group with CTX injection alone. Fibers with central nucleus were noted in the group with CTX injection with or without overloading. The rate of disappearance of fibers having central nucleus during recovery was stimulated by overloading. Histological analyses revealed that the regeneration of injured soleus muscle with overloading proceeded more rapidly than the muscle without overloading. These results, in combination with previous lines of evidence, strongly suggest that functional overloading may facilitate the regeneration of injured skeletal muscles.

Long-term outcome of joint-preserving surgery by combination metatarsal osteotomies for shortening for forefoot deformity in patients with rheumatoid arthritis

Abstract Objectives. We report the long-term outcome of joint-preserving surgery by combining metatarsal osteotomies for shortening for forefoot deformity in patients with rheumatoid arthritis (RA). Methods. Forty-three patients (57 feet) aged 41.7–70.8 years (mean, 57.7 years) underwent a combination of first tarsometatarsal fusion and distal realignment (modified Lapidus procedure), shortening oblique osteotomies of the bases of metatarsals 2–4, and fifth ray osteotomy (modified Coughlin procedure). Patients were followed up for 64–108 months (mean, 76.6 months). Results. Average postoperative Foot Function Index scores for pain, disability, and activity were 10.3, 19.9, and 16.2, respectively. Average Japanese Society for Surgery of the Foot RA foot and ankle score improved significantly from 52.1 points preoperatively to 90.3 points postoperatively. Postoperatively, 41% of patients reported some forefoot stiffness, but showed no disability. Residual deformity and callosity were absent in all patients. Average hallux valgus and intermetatarsal angles decreased postoperatively from 48.5° to 8.6° and from 15.2° to 4.6°, respectively. Nonunion in two metatarsals, hardware breakage in three, and mild infection in one were identified during follow-up. Conclusions. With good perioperative medical management of RA, surgical repositioning of the metatarsophalangeal joints by proximal metatarsal shortening and consequent relaxing of the surrounding soft tissue shows successful long-term results.

Microcurrent Electrical Nerve Stimulation Facilitates Regrowth of Mouse Soleus Muscle

Microcurrent electrical nerve stimulation (MENS) has been used to facilitate recovery from skeletal muscle injury. However, the effects of MENS on unloading-associated atrophied skeletal muscle remain unclear. Effects of MENS on the regrowing process of unloading-associated atrophied skeletal muscle were investigated. Male C57BL/6J mice (10-week old) were randomly assigned to untreated normal recovery (C) and MENS-treated (M) groups. Mice of both groups are subjected to continuous hindlimb suspension (HS) for 2 weeks followed by 7 days of ambulation recovery. Mice in M group were treated with MENS for 60 min 1, 3, and 5 days following HS, respectively, under anesthesia. The intensity, the frequency, and the pulse width of MENS were set at 10 μA, 0.3 Hz, and 250 msec, respectively. Soleus muscles were dissected before and immediately after, 1, 3 and 7 days after HS. Soleus muscle wet weight and protein content were decreased by HS. The regrowth of atrophied soleus muscle in M group was faster than that in C group. Decrease in the reloading-induced necrosis of atrophied soleus was facilitated by MENS. Significant increases in phosphorylated levels of p70 S6 kinase and protein kinase B (Akt) in M group were observed, compared with C group. These observations are consistent with that MENS facilitated regrowth of atrophied soleus muscle. MENS may be a potential extracellular stimulus to activate the intracellular signals involved in protein synthesis.

The DNA Repair Enzyme Apurinic/Apyrimidinic Endonuclease (Apex Nuclease) 2 Has the Potential to Protect against Down-Regulation of Chondrocyte Activity in Osteoarthritis

Apurinic/apyrimidinic endonuclease 2 (Apex 2) plays a critical role in DNA repair caused by oxidative damage in a variety of human somatic cells. We speculated that chondrocyte Apex 2 may protect against the catabolic process of articular cartilage in osteoarthritis (OA). Higher levels of Apex 2 expression were histologically observed in severely compared with mildly degenerated OA cartilage from STR/OrtCrlj mice, an experimental model which spontaneously develops OA. The immunopositivity of Apex 2 was significantly correlated with the degree of cartilage degeneration. Moreover, the OA-related catabolic factor interleukin-1β induced the expression of Apex 2 in chondrocytes, while Apex 2 silencing using small interfering RNA reduced chondrocyte activity in vitro. The expression of Apex 2 in chondrocytes therefore appears to be associated with the degeneration of articular cartilage and could be induced by an OA-related catabolic factor to protect against the catabolic process of articular cartilage. Our findings suggest that Apex 2 may have the potential to prevent the catabolic stress-mediated down-regulation of chondrocyte activity in OA.

Peroneal spastic flatfoot in adolescents with accessory talar facet impingement: a preliminary report.

This study analyzed imaging, arthroscopic findings, and treatment responses for peroneal spastic flatfoot (PSFF) caused by talocalcaneal impingement at the accessory anterolateral talar facet (AALTF) (accessory talar facet impingement) in 13 adolescents without histories of trauma and tarsal coalition. The AALTF was determined with computed tomography and MRI. Focal abutting bone marrow edema (FABME) on MRI around the AALTF was confirmed. In seven patients who underwent AALTF resection, subtalar arthroscopy was performed. All experienced alleviation PSFF after treatment; reduction in FABME was observed. AALTF resection alone is beneficial for PSFF caused by accessory talar facet impingement when peroneal spasms are restored by an injection of local anesthesia.

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.

Changes of SM Muscles After STG Harvest

Semimembranosus (SM) muscle as well as Semitendinosus-Gracilis (STG) tendon have the same role in knee flexion and tibial internal rotation. Because STG tendons are generally used for anterior cruciate ligament (ACL) reconstruction, some compensational changes in SM muscle might have been induced. The purpose of this study was to investigate the changes of SM muscle affected by harvesting STG tendons. 10 Wistar-strain male rats were divided into control (C) and STG-dissected (STG) groups. Left STG tendons including the distal half of muscle portions were dissected in group STG and only skin incision was performed in group C. 4 weeks after the treatments, fiber types classification and ultrastructural observations were performed. In group STG the decrease of type IIa (fast-twitch fiber with high oxidative capacity) was observed in deep layers of SM muscle (p<0.01). In ultrastructural observations, the increase in lipid droplets and mitochondria and the irregularity of Z disc were observed in deep layers. These morphological changes indicated that the mechanical loading might increase in SM muscle after harvesting of STG. Because of minor injuries in SM muscle, hamstring strength exercise at early stage of rehabilitation program should be carefully performed following ACL reconstruction using STG tendons in clinical practice.

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.