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Biomedical subjects

Tatsuya Koike

Publications and source records attributed to Tatsuya Koike.

At least 19 recordsLinked to original sources
PubMed2007

Midterm results of revision total elbow arthroplasty in patients with rheumatoid arthritis.

We retrospectively reviewed the clinical and radiographic results of 30 revision total elbow arthroplasties in patients with rheumatoid arthritis using original surface prostheses developed in our institution. We asked whether a surface prosthesis is a suitable option for reconstructing a failed surface total elbow arthroplasty in terms of reproducing clinical performance compared with other devices such as semiconstrained prostheses. All 30 failed total elbow arthroplasties were performed with various surface prostheses and revised with Dogo Onsen Hospital surface prostheses. The mean age of the patients at the time of surgery was 64.9 years (range, 44-83 years), and the minimum followup was 3 years (mean 6.7 years; range, 3-11 years). The Mayo elbow performance index improved from 42.3 preoperatively to 76.3 at last followup. Pain, stability, and function scores improved after revision surgery, but range of motion scores were unchanged. Our data indicate a surface prosthesis is a reasonable option for reconstructing failed surface total elbow arthroplasties in patients with rheumatoid arthritis.

Adult↗
PubMed2006

Heparin potentiates the in vivo ectopic bone formation induced by bone morphogenetic protein-2.

Although bone morphogenetic proteins (BMPs) are clinically useful for bone regeneration, large amounts are required to induce new bone formation in monkeys and humans. We found recently that heparin stimulates BMP activity in vitro (Takada, T., Katagiri, T., Ifuku, M., Morimura, N., Kobayashi, M., Hasegawa, K., Ogamo, A., and Kamijo, R. (2003) J. Biol. Chem. 278, 43229-43235). In the present study, we examined whether heparin enhances bone formation induced by BMPs in vivo and attempted to determine the molecular mechanism by which heparin stimulates BMP activity using C2C12 myoblasts. Heparin enhanced BMP-2-induced gene expression and Smad1/5/8 phosphorylation at 24 h and thereafter, although not within 12 h. Heparitinase treatment did not affect the response of cells to BMP-2. In the presence of heparin, degradation of BMP-2 was blocked, and the half-life of BMP-2 in the culture medium was prolonged by nearly 20-fold. Although noggin mRNA was induced by BMP-2 within 1 h regardless of the presence of heparin, noggin failed to inhibit BMP-2 activity in the presence of heparin. Furthermore, simultaneous administration of BMP-2 and heparin in vivo dose-dependently induced larger amounts of mineralized bone tissue compared with BMP-2 alone. These findings clearly indicate that heparin enhances BMP-induced osteoblast differentiation not only in vitro but also in vivo. This study indicates that heparin enhances BMP-induced osteoblast differentiation in vitro and in vivo by protecting BMPs from degradation and inhibition by BMP antagonists.

Alkaline Phosphatase↗
PubMed2006

Volar dislocation of the extensor carpi ulnaris tendon on magnetic resonance imaging is associated with extensor digitorum communis tendon rupture in rheumatoid wrists.

PURPOSE: Extensor tendon rupture in rheumatoid wrists is a common problem and causes immediate dysfunction of the digits. The best treatment for tendon rupture may be prophylactic management, although the factors associated with tendon rupture must first be identified. The purpose of this study was to evaluate structures around rheumatoid wrists using magnetic resonance imaging with forearm rotation and to identify factors associated with extensor tendon rupture as indications for prophylactic surgery. METHODS: The subjects were 34 patients (40 wrists) with active rheumatoid arthritis. The extensor digitorum communis (EDC) tendons were ruptured in 15 wrists. Magnetic resonance imaging of the wrists was performed in maximally pronated and supinated positions of the forearm. Axial images of the distal radioulnar joints (DRUJs) were selected to evaluate DRUJ synovitis, dorsal tenosynovitis, volar dislocation of the extensor carpi ulnaris (ECU) tendon, sigmoid notch angle, and the radioulnar ratio (RUR) (ie, the degree of DRUJ subluxation). RESULTS: No significant correlations were found between EDC tendon rupture and DRUJ synovitis, dorsal tenosynovitis, or RUR in pronation. Extensor digitorum communis tendon rupture correlated significantly with volar ECU tendon dislocation, sigmoid notch angle, and RUR in supination. Radioulnar ratio correlated significantly with volar ECU tendon dislocation only in supination and not in pronation. Thus, DRUJ subluxation was advanced even in the supinated wrist with volar ECU tendon dislocation. As a factor associated with EDC tendon rupture, volar ECU tendon dislocation had 87% sensitivity and 76% specificity. CONCLUSIONS: Volar ECU tendon dislocation is associated with increased RUR in supination and EDC tendon rupture. Volar ECU tendon dislocation can thus be considered a factor associated with EDC tendon rupture, and its presence may indicate the need for prophylactic surgical intervention in a subset of rheumatoid arthritis patients.

Adolescent↗
PubMed2006

[The best physical therapy for osteoporosis].

Osteoporosis and osteoporotic fractures have become an epidemic in the industrialized world. Osteoporosis, low bone mass, is a silent condition with microarchitectural deterioration of the bone structure leading to decreased bone strength and osteoporotic fractures. Physical activity has been advocated as offering a potential means to increase and maintain bone mineral density. Previous cross-sectional studies showed that there is a strong association between exercise and bone mineral density, especially in athletic individuals. However, there might be a self-selection bias; i.e. individuals with larger muscles and bones are more likely to choose an athletic lifestyle. Although there is a report that physical activity is associated with a reduced risk for hip fracture among older community-dwelling women, the effects of vigorous exercises building bone mass is modest and considerably less than bisphosphonates. The proper evaluation of exercise as a preventative therapy for osteoporosis should focus on prevention of falls or osteoporotic fractures.

Accidental Falls↗
PubMed2006

[Progress in external hip protectors].

Hip fractures are a major cause of disability, impairment and death in elderly people. It has been reported that bisphosphonates significantly reduce the risk of hip fracture among elderly women with confirmed osteoporosis but not among elderly women selected primarily on the basis of risk factors other than low bone mineral density. External hip protectors have been developed as a measure of reducing the impact of the fall and thereby the chance of hip fractures in such high risk people. The results of 14 randomized controlled trials for the prevention of hip fractures by using hip protectors have been reported until 2004. However, Cochrane review of hip protectors has concluded that their effectiveness is uncertain. Although further research is required with different conditions, the most important issue of hip protectors is the low adherence rate.

Aged↗
PubMed2006

[Destruction of articular cartilage].

Proinflammatory cytokines, such as interleukin-1 (IL-1) and tumour necrosis factor alpha (TNF alpha), have been implicated in the dysregulation of bone and cartilage remodelling characteristic of rheumatoid arthritis (RA) and/or osteoarthritis (OA). These cytokines increase production of factors that stimulate cartilage matrix degradation such as metalloproteinases. The matrix metalloproteinases (MMPs), the a disintegrin and metalloproteinase (ADAMs) and a disintegrin and metalloproteinase with thrombospondin repeats (ADAM-TSs) are secreted by many cell types including chondrocytes and cells in the synovium under the influences of cytokines. The role of the matalloproteinases in the irreversible degradation of articular cartilage has been extensively documented. We have already succeeded in halting the progression of joint damage by RA using anti-TNF therapy. The precise understanding of the roles of metalloproteinases should provide new therapeutic strategies for OA.

Arthritis, Rheumatoid↗
PubMed2006

[Do hip protectors decrease the risk of hip fracture in elderly?].

Efforts aimed at preventing hip fractures include lifestyle advice for high-risk elderly, interventions to reduce the risk of falls and medication for osteoporosis. Alternative approach is the use of hip protectors. Hip protectors have pads designed to cover the greater trochanter and attenuate or disperse the force of a fall sufficiently to prevent a hip fracture. There are 14 randomized controlled trials (RCTs) included in the Cochrane systematic review until 2005. All RCTs were classified into three groups by the type of randomization; cluster randomized in institutions, individually randomized in institutions and individually randomized in community. There is little evidence to support the use of hip protectors outside the nursing home setting. Further research is required, primarily to produce a device that provide higher compliance, and which will then need to be tested in another RCT.

Aged↗
PubMed2005

Bone morphogenetic protein activities are enhanced by 3',5'-cyclic adenosine monophosphate through suppression of Smad6 expression in osteoprogenitor cells.

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor (TGF)-beta superfamily, and some display potent osteogenic activity both in vivo and in vitro. The BMP signaling cascade involving BMP receptors at the cell membrane and intracellular messengers (Smads) has been elucidated, but the regulatory mechanisms of BMP signaling have not been clarified. We previously found that pentoxifyline (PeTx), a nonspecific inhibitor of phosphodiesterase (PDE), and rolipram, a PDE-4-specific inhibitor, enhance BMP-4-induced osteogenic differentiation of mesenchymal cells, probably through the elevation of intracellular cyclic adenosine monophosphate (cAMP) accumulation and modulation of BMP signaling pathways as enhanced BMP-4 action was reproduced by addition of dibutylyl-cAMP (dbcAMP). However, the precise mechanisms underlying the enhancing effects of those agents on BMP signaling were not completely revealed. As already reported, BMPs utilize a specific intracellular signaling cascade to target genes via R-Smads (Smad1,5,8), Co-Smad (Smad4) and I-Smads (Smad6,7). One possibility for cAMP-mediated effects on BMP signaling might be suppression of I-Smads expression since these proteins form a negative feedback loop in BMP signaling. To examine this possibility, changes in I-Smad (Smad6) expression on addition of dbcAMP or PeTx were examined in a bone-marrow-derived osteogenic cell line (ST2). Alkaline phosphatase activity in ST2 cells was consistently induced by BMP-4 treatment (300 ng/ml), and Smad6 mRNA expression was also induced by BMP-4 treatment. Although concurrent treatment of ST2 cells with BMP-4 and dbcAMP elicited further activation of alkaline phosphatase, addition of dbcAMP reduced BMP-4-induced Smad6 expression in a dose-dependent manner. Furthermore, detection of phosphorylated Smad1/5/8 on Western blotting analysis was prolonged, suggesting prolonged kinase activity of BMP receptors through suppressed expression of Smad6. Elevated intracellular cAMP might thus enhance BMP signaling by suppressing Smad6 induction and prolonging intracellular BMP signaling.

Alkaline Phosphatase↗
PubMed2005

Use of local electroporation enhances methotrexate effects with minimum dose in adjuvant-induced arthritis.

OBJECTIVE: To investigate the effects of electrical pulses on the ability of methotrexate (MTX) to attenuate inflammation and subsequent joint destruction in rats with adjuvant-induced arthritis (AIA). METHODS: Rats in the experimental group received an intraperitoneal injection of MTX (0.125 mg/kg body weight), followed 30 minutes later by application of direct electrical pulses (50V, 8 Hz) to their left hind paws with an electroporation apparatus (M+/E+ group; n = 8). The procedure was repeated twice weekly for 3 weeks. Three control groups received the following treatments, respectively: MTX without electrical treatment (M+/E- group; n = 9), electrical treatment but no MTX (M-/E+ group; n = 10), or no electrical treatment and no MTX (M-/E- group; n = 9). Progression of AIA was monitored by joint swelling and radiologic and histologic changes in the ankle joint. RESULTS: Three weeks after injection of the adjuvant, and at the height of the arthritic reaction, the swelling and radiologic and histologic changes in the left hind paws in the M+/E+ rats were significantly reduced, as compared with changes observed in the control groups. CONCLUSION: These results demonstrate that application of electrical pulses in combination with use of systemic low-dose MTX can ameliorate local arthritic reactions. This response probably occurs because electrical stimulation promotes transient passage of MTX through pores in the cell membranes, with a resultant local increase in the concentration of the drug within the cells. These results point to a potential use of electrochemotherapy to increase the efficacy of MTX or other drugs in an arthritic joint that is refractory to treatment, without increasing the dose of the drug.

Animals↗
PubMed2005

Evaluation of rotator cuff tears with magnetic resonance arthrography.

The size and morphologic features of rotator cuff tears may influence treatment selection and affect final outcomes. Magnetic resonance arthrography allows observation of these features and other intraarticular structures. To assess the utility of magnetic resonance imaging in assessing size and morphologic features, we retrospectively reviewed observations on 41 shoulders in 37 consecutive surgically treated patients (mean age, 63.2 years) who had magnetic resonance imaging followed by magnetic resonance arthrography. The maximum rotator cuff defect size in the anteroposterior direction defined transverse size, and the maximum rotator cuff defect size in the mediolateral direction defined longitudinal size. Sensitivities for detecting full-thickness rotator cuff tears by magnetic resonance imaging and magnetic resonance arthrography were 90.2% and 100%, respectively. Maximum longitudinal and transverse dimensions of the tear as shown by magnetic resonance arthrography correlated better with intraoperative measurements (r2 = 0.85 transversely, 0.92 longitudinally) than magnetic resonance imaging measurements (r2 = 0.47 transversely, 0.26 longitudinally). The reproducibility of the two methods is similar. Magnetic resonance arthrography also allowed morphologic classification of the torn tendon as blunt end, tapering end, indistinct end, horizontal tear, and global tear. There was good agreement in classifying torn edges; the imaging findings agreed with findings at surgery. Magnetic resonance arthrography was more accurate in evaluating rotator cuff tear size and morphologic features than conventional magnetic resonance imaging.

Adult↗
PubMed2005

[Evaluation of exercise as a preventive therapy for osteoporosis].

Osteoporosis and osteoporotic fractures have become an epidemic in the industrialized world. Osteoporosis, low bone mass, is a silent condition with microarchitectural deterioration of the bone structure leading to decreased bone strength and osteoporotic fractures. Physical activity has been advocated as offering a potential means to increase and maintain bone mineral density. Previous cross-sectional studies showed that there is a strong association between exercise and bone mineral density, especially in athletic individuals. However, there might be a self-selection bias; i.e. individuals with larger muscles and bones are more likely to choose an athletic lifestyle. Although there is a report that physical activity is associated with a reduced risk for hip fracture among older community-dwelling women, the effects of vigorous exercises building bone mass is modest and considerably less than bisphosphonates. The proper evaluation of exercise as a preventative therapy for osteoporosis should focus on prevention of falls or osteoporotic fractures.

Accidental Falls↗
PubMed2004

Open reduction of the dislocated hip in juvenile idiopathic arthritis: a case report.

An 8-year-old girl with systemic-onset juvenile idiopathic arthritis (JIA) required surgical reduction for a dislocated left hip joint following failure of skin traction for 1 week. Unaided walking was achieved by 3 months postoperatively. Incongruence and irregularity of the hip joint remained but may resolve with maturation. Joint laxity caused by synovitis, flexion/adduction contracture with pain, and acetabular dysplasia by growth disturbance apparently caused hip dislocation.

Journal Article↗