Biomedical subjects

Tatsuya Koike

Publications and source records attributed to Tatsuya Koike.

23 records · Page 2Linked to original sources

PubMed2003

High serum levels of menatetrenone in male patients with ossification of the posterior longitudinal ligament.

STUDY DESIGN: This work was performed to investigate the role of vitamin K (VK) in the pathogenesis of ossification of posterior longitudinal ligament (OPLL), by analyzing the biochemical markers of the blood samples of OPLL patients and responses of ligament cells derived from OPLL lesion to VK2. OBJECTIVES: The pathogenesis of OPLL, classified as a form of diffuse idiopathic skeletal hyperostosis, is still unclear. In this study, we investigated the role of menaquinone (VK2) in patients with OPLL (OPLL patients) and the effects of VK2 on ligament cells isolated from OPLL lesion. METHODS: Serum levels of intact osteocalcin, glu-osteocalcin, MK-4, -7 (VK2 variants) and other minerals in spot blood samples were measured in 24 OPLL patients and in 24 age-matched control patients (non-OPLL patients). The cultured cells isolated from an OPLL patient were treated with MK-4. Alkaline phosphatase (Al-p) activity and osteocalcin release were measured after 2 weeks of culture. RESULTS: In the clinical study, the serum MK-4 in male OPLL patients was significantly higher than that in male non-OPLL patients. However, among female patients, the difference was not significant. Although the serum osteocalcin in females was significantly higher than that in males, there was no significant difference between the OPLL and non-OPLL groups. In in vitro study, MK-4 did not increase Al-p activity in the ligament cells isolated from nonossified region of OPLL patient. Osteoblastic activity of the cultured cells was not stimulated by MK-4. CONCLUSION: From these results and previous reports, we propose the possibility of the impediment in VK2 metabolism in OPLL patients. The results also implicate the gender tendency in OPLL, because the difference of serum level of MK-4 in OPLL patients was significant only in male.

Aged↗

PubMed2003

Effects of leptin to cultured growth plate chondrocytes.

OBJECTIVE: This study aimed to evaluate whether leptin has any effect on growth plate chondrocytes. METHODS: We studied the effects of exogenous leptin on cultured rabbit growth plate chondrocytes. This involved assessing [3H]thymidine incorporation, alkaline phosphatase (ALP) activity, proteoglycan production, leptin receptor (Ob-R) activity, and detection of Ob-R using Western blot analysis. RESULTS: The existence of Ob-R in growth plate chondrocytes was revealed by Western blot and Ob-R activity. Prior to semiconfluence, leptin increased [3H]thymidine incorporation while at the semiconfluent and early confluent stages, leptin promoted ALP activity and tended to promote proteoglycan production. CONCLUSION: Growth plate chondrocytes possess Ob-Rs, and leptin enhance chondrocyte proliferation and subsequent cell differentiation.

Alkaline Phosphatase↗

PubMed2002

The Wnt antagonist Frzb-1 regulates chondrocyte maturation and long bone development during limb skeletogenesis.

The Wnt antagonist Frzb-1 is expressed during limb skeletogenesis, but its roles in this complex multistep process are not fully understood. To address this issue, we determined Frzb-1 gene expression patterns during chick long bone development and carried out gain- and loss-of-function studies by misexpression of Frzb-1, Wnt-8 (a known Frzb-1 target), or different forms of the intracellular Wnt mediator LEF-1 in developing limbs and cultured chondrocytes. Frzb-1 expression was quite strong in mesenchymal prechondrogenic condensations and then characterized epiphyseal articular chondrocytes and prehypertrophic chondrocytes in growth plates. Virally driven Frzb-1 misexpression caused shortening of skeletal elements, joint fusion, and delayed chondrocyte maturation, with consequent inhibition of matrix mineralization, metalloprotease expression, and marrow/bone formation. In good agreement, misexpression of Frzb-1 or a dominant-negative form of LEF-1 in cultured chondrocytes maintained the cells at an immature stage. Instead, misexpression of Wnt-8 or a constitutively active LEF-1 strongly promoted chondrocyte maturation, hypertrophy, and calcification. Immunostaining revealed that the distribution of endogenous Wnt mediator beta-catenin changes dramatically in vivo and in vitro, from largely cytoplasmic in immature proliferating and prehypertrophic chondrocytes to nuclear in hypertrophic mineralizing chondrocytes. Misexpression of Frzb-1 prevented beta-catenin nuclear relocalization in chondrocytes in vivo or in vitro. The data demonstrate that Frzb-1 exerts a strong influence on limb skeletogenesis and is a powerful and direct modulator of chondrocyte maturation, phenotype, and function. Phases of skeletogenesis, such as terminal chondrocyte maturation and joint formation, appear to be particularly dependent on Wnt signaling and thus very sensitive to Frzb-1 antagonistic action.

Animals↗

PubMed2002

[Effect of exercise as a therapy for osteoporosis on bone metabolism].

Exercise affects bone mass most effectively in adolescence depending its property. For postmenopausal women, resistance or high-impact loading training are suggested as preventative exercise against bone loss at the femoral neck. Physical exercise affects the balance of bone turnover. However, there is the discrepancy between studies on bone metabolic markers at present. In my opinion, the proper evaluation of exercise for osteoporosis should focus on prevention of falls.

English Abstract↗

PubMedDate not supplied

Computerized assessment of Bankart lesions under tension with magnetic resonance arthrography.

Accurate anatomic depiction of Bankart lesions based on magnetic resonance imaging (MRI) is crucial for the treatment of posttraumatic recurrent dislocation of the glenohumeral joint. MR arthrography, the intraarticular injection of dilute gadolinium before MR imaging, improves sensitivity in the detection of shoulder pathology. Abduction and external rotation (ABER) of the shoulder places dynamic stress on the inferior capsular pouch and anterior labroligamentous complex, important structures for anterior shoulder stability. This study sought to determine whether MR arthrography, by use of computerized image analysis, can visualize Bankart lesions better with the shoulder in the neutral position or in ABER. We evaluated 12 shoulders after traumatic anterior dislocation. The MR images were analyzed with image-analyzing software. We compared 3 parameters at 5 levels of the glenoid in the neutral position and in ABER: detachment (the length of detachment between the anterior glenoid rim and the anterior periosteal attachment), displacement (the distance between the anterior glenoid rim and the tip of the displaced labrum), and Bankart area (the area bounded by the detachment line, the displacement line, and the anterior aspect of the Bankart lesion). MR images revealed that Bankart lesions were under tension in ABER and lax and redundant with the shoulder in the neutral position. All 3 parameters were greater in ABER than in the neutral position in all cases (P = .012, P = .0006, and P = .012). Computerized image assessment of MR arthrography with the shoulder in ABER provides excellent visualization and evaluation of Bankart lesions.

Adolescent↗