Michihisa Zenmyo

Kagoshima University, Kagosima, Kagoshima, Japan

Are you Michihisa Zenmyo?

Claim your profile

Publications (35)95.67 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Biofilms play a pivotal role in medical device-related infections. However, epidemiological analysis of biofilm formation and genotyping among clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients with orthopaedic infections has rarely been reported. A total of 168 MRSA strains were examined: 23 strains from patients with device-related infection (the device group); 55 from patients with device-non-related infection (the nondevice group); and 90 from asymptomatic nasal carriers (the colonization group). Pulsed-field gel electrophoresis analysis and five genotyping methods including agr typing were performed. Biofilm formation was quantified using a microtitre plate assay. The device group had a significantly higher incidence of agr-2 than the colonization group (78.3% vs. 34.4%, P=0.001). The biofilm index of the agr-2 (0.523 ± 0.572) strains was significantly higher than those of agr-1 (0.260 ± 0.418, P<0.0001) and agr-3 (0.379 ± 0.557, P=0.045). The prevalence of strong biofilm formers in the device group (43.5%) was significantly higher than that in the nondevice group (12.7%, P=0.003) and the colonization group (20.0%, P=0.020). agr-2 MRSA strains may be more likely to cause orthopaedic device infection because of their strong biofilm formation ability.
    FEMS Immunology & Medical Microbiology 05/2011; 63(1):10-5. · 2.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To reveal the factors that determine the natural course of subluxation of occipital-cervical lesions in rheumatoid arthritis (RA). The atlanto-axial region is one of the most common locations for lesions in RA. Some cases progress from reducible atlanto-axial subluxation (AAS) to irreducible vertical migration, while others continue to exhibit reducible AAS. No study has revealed the factors that determine the natural course of subluxation. We focus on the odontoid as a key structure of the progression of occipito-cervical lesions and investigated this region in patients with RA using reconstructive computed tomography (CT) images, and analyzed factors in association with CT findings. Fifty-eight patients with RA and 40 age-matched controls, all women, were studied. Associated factors, including C-reactive protein, erythrocyte sedimentation rate, steroid usage, and the severity of local osteoporosis, were analyzed as measurements in association with odontoid destruction. The destruction of odontoid and atlanto-odontoid joint were common in patients with RA. The more destruction observed in the odontoid process, the greater is the degree of progression of vertical migration. Local osteoporosis is a significant factor in odontoid destruction, based on a cortico-cancellous index of 42% in cases of grade III odontoid destruction. The odontoid process is a key structure in the progression of occipito-cervical lesions in patients with RA.
    The Journal of Rheumatology 03/2011; 38(5):863-7. · 3.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A prospective study. To assess the outcome of patients with a single thoracolumbar burst fracture treated with circumferential short-segment fusion consisting of posterior reduction, short-segment fusion, and delayed staged mini-open anterior short-segment fusion. The surgical treatment of thoracolumbar burst fractures remains controversial. In attempting to combine the advantages of posterior procedures, including initial correction of kyphosis and early decompression, and those of anterior procedures, including direct decompression and restoration of anterior column support, a combined posterior and delayed staged anterior procedure seems to be a reasonable choice. However, conventional combined procedures are invasive. We prospectively selected 28 consecutive patients with single thoracolumbar burst fracture for circumferential short-segment fusion consisting of posterior reduction, short-segment fusion, and delayed staged mini-open anterior short-segment fusion. The pedicle screw systems were removed after confirmation of posterior bony fusion to preserve as many motion segments as possible in those patients who could be treated with circumferential monosegmental fusion. Radiographic and clinical assessment of 28 patients who received this treatment was carried out. The mean loss of correction of kyphosis between the time of the combined procedure and final follow-up was 3.7 degrees (range, 0 to 10.2 degrees). Bony fusion was eventually achieved in all patients. There were 15 cases with monosegmental and 13 cases with bisegmental circumferential fusion. All 10 patients with initial neurological deficit improved by at least 1 Frankel grade: 3 improved by 1 grade, 5 improved by 2 grades, and 2 improved by 3 grades. In total, 27 patients, who were P1 or P2 on the Denis pain scale, were considered to have obtained clinically satisfactory results. This combined procedure is less invasive than the conventional combined one, and finally achieves shorter stabilization, resulting in preservation of motion segments. It thus seems to be a reasonable treatment option for thoracolumbar burst fractures.
    Journal of spinal disorders & techniques 03/2011; 25(1):38-46. · 1.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Osteoid osteoma of the spine is a relatively rare bone-forming tumor. Pain that is worse at night and relieved by aspirin and muscle contracture are the most characteristic symptoms of spinal osteoid osteoma. Although radicular pain occasionally occurs in spinal osteoid osteoma, spinal cord and nerve root compression is absent in most cases. Although radicular pain appears to be associated with tumorous inflammation, there have been no presentations of histological findings of inflammation around the nerve root. We present here two rare cases of spinal osteoid osteoma causing radiculopathy and the first histological evidence of tumorous inflammation as a cause of radiculopathy in osteoid osteoma near the intervertebral foramen.
    Diagnostic Pathology 01/2011; 6:10. · 2.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a case of a 69-year-old man with dropped head syndrome associated with isolated neck extensor myopathy (INEM). Over a period of 2 years, he exhibited progressive inability to lift his chin off his chest, resulting in the dropped head position that impaired his activities of daily living. He had a disturbed gait with severe imbalance of spinal alignment. Computed tomography revealed osseous contracture of cervical vertebral bodies in flexed position. Anterior combined posterior reconstruction surgery yielded a successful outcome in his activities of daily living, including his walking balance of spinal alignment. Pathologic study confirmed myogenic atrophy in the cervical extensor muscles. We suggest that consideration for surgical management should be given to dropped head syndrome especially due to INEM.
    Diagnostic Pathology 01/2011; 6:9. · 2.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tethered cord syndrome with spinal lipoma is the most common form of occult spinal dysraphism. For the symptomatic patients, surgical treatment is recommended; however, there are many patients who have not been encouraged to seek medical attention until adulthood, since their symptoms are not severe enough to interfere with their daily activities. We performed pedicle subtraction osteotomy (PSO) to achieve indirect untethering and neural decompression in two senior patients with tethered cord syndrome, who showed deteriorating neurological condition due to coexisting lumbar canal stenosis. Here we report two patients (aged 56 and 60 years) who underwent PSO of L3 or L4. The pain disappeared and the bladder dysfunction recovered significantly after surgery. Complete bone union and untethering were achieved in both patients. PSO is an alternative surgical technique for senior patients with tethered cord syndrome caused by lumbosacral spinal lipoma, when the syndrome occurs along with lumbar canal stenosis.
    The International journal of neuroscience 11/2010; 120(11):735-7. · 0.86 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although the diagnosis of chondrosarcoma, especially the distinction between enchondroma and low-grade chondrosarcoma or low-grade chondrosarcoma and high-grade chondrosarcoma, is pathologically difficult, differential diagnosis is very important because the treatment strategies for these diseases are completely different. The grading system is crucial in predicting biologic behavior and prognosis, however, exact pathological grading is difficult using only routine examinations because the criteria of the grading system are not necessarily definitive. Growth arrest and DNA damage-inducible protein 45β (GADD45β) is an essential molecule for chondrocytes during terminal differentiation. In the present study, we investigated the immunohistochemical expression of GADD45β in enchondroma, and chondrosarcoma of histological grades I, II, and III, to clarify the diagnostic significance of GADD45β in pathological grading of chondrosarcoma. Twenty samples (enchondroma = 6, chondrosarcoma grade I = 7, grade II = 6, grade III = 1) were used for immunohistochemical analysis to investigate the expression of GADD45β. Quantitative analysis was performed to compare the number of GADD45β positive cells and pathological grading. Over 70% of the cells in enchondromas expressed GADD45β. On the other hand, the expression of GADD45β decreased significantly according to the histological grade of chondrosarcoma (grade I: 45%; grade II: 13.8%; and grade III: 3.8%). The association of GADD45β expression and pathological grading of chondrosarcoma in the present study suggests that the immunohistochemical study of GADD45β may be a specific diagnostic parameter for chondrosarcoma cell differentiation.
    Diagnostic Pathology 10/2010; 5:69. · 2.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Spinal subependymomas, which have a relatively benign nature, are very rare tumors. It is difficult to distinguish spinal subependymomas from other intramedullary spinal tumors based on neuroradiological findings. A case of cervical intramedullary subependymoma in a 63-year-old female is reported. The diffused enlargement of the spinal cord at C2 level involved the lesion with isointensity on a T1-weighted MRI and relatively high intensity on a T2-weighted MRI. Enhancement in the small part of the tumor was observed on a T1-weighted MRI with gadolinium administration. The tumor occupied the left side of the spinal cord, and was totally removed through a laminoplasty of C2. Immunohistochemistry was useful for pathological diagnosis. The clinical feature of this patient is described with the review of literatures.
    The International journal of neuroscience 10/2010; 120(10):676-9. · 0.86 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The N-myc downstream regulated gene 1 (NDRG1)/Cap43 is closely associated with cell differentiation, and its expression is induced by hypoxia and increasing intracellular calcium levels. Whether the NDRG1/Cap43 expression in cancer cells is a predictive marker of good or poor prognosis in patients, depends upon tumor types and differentiation status. In this study, we examined whether the NDRG1/Cap43 expression was involved in the differentiation of osteosarcoma cells, using three osteosarcoma cell lines, MG63, U2OS and SaOS2. The NDRG1/Cap43 expression in MG63 and U2OS was significantly enhanced by vitamin D3, which also induced the production of osteocalcin, a differentiation marker of osteoblasts. The knockdown of NDRG1/Cap43 using small interfering RNA also suppressed the production of osteocalcin and enhanced cell proliferation, accompanied by the suppression of p21 expression. Furthermore, the acquired invasiveness of osteosarcoma cells during the invasion in Matrigel resulted in the decreased expression of NDRG1/Cap43. On the basis of these results, our proposed role for NDRG1/Cap43 would be in the capacity of differentiation and invasion in osteosarcoma cells.
    Oncology Reports 09/2010; 24(3):721-5. · 2.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Intradural neurenteric cysts are rare congenital lesions and arise from incomplete separation of the developing notochord and foregut in the embryo. Neurenteric cysts are often seen in conjunction with other forms of occult spinal dysraphism. The cases of a 48-year-old male with pain in the right shoulder and numbness in both hands and a 7-year-old girl with subacute muscle weakness of the lower extremities are presented. Both patients underwent surgery. One lesion was completely excised, while the other could be only partially removed because of negative monitoring potential during the operation. Histological examination, showing pseudostratified ciliated columnar epithelium, confirmed the diagnosis of neurenteric cyst. The symptoms in both patients nearly disappeared after surgery. Recurrence of cyst was observed in the girl, though without neurological symptoms. In conclusion, two cases of intradural extramedullary cysts are reported. Clinical presentations, intraoperative findings, and histological features are discussed with a review of the literature.
    The International journal of neuroscience 09/2010; 120(9):625-9. · 0.86 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To examine the radiological features of vertebral artery (VA) displacement/occlusion associated with rheumatoid arthritis (RA) spine using magnetic resonance angiography. Forty-seven RA patients with upper cervical lesions were evaluated for patency or abnormality of the VA by extracranial magnetic resonance angiography, with comparison of findings with those of 46 healthy volunteers. VA occlusion occurred in 4 patients (8.5%) and VA stenosis in 9 patients (19.1%). Anomaly of the VA was also observed in 3 patients (6.4%). No occlusion or anomaly was found in healthy volunteers, but 1 case of stenosis was found. Severity of vertical subluxation was correlated with the presence of VA abnormality in RA patients. The incidence of VA abnormality was 34% in RA patients and 2% in healthy volunteers. Magnetic resonance angiography is useful for screening for abnormality of the entire VA.
    Neurosurgery 06/2010; 66(6):1174-80; discussion 1180. · 2.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The immunohistological features and surgical treatment of an intramedullary ependymal cyst in the conus medullaris is presented. An intramedullary ependymal cyst is a rare lesion of dysembryoplastic origin. There have been only seven patients reported with pathologically proven ependymal cysts in the conus medullaris. A 64-year-old woman reported pain and numbness in both thighs and feet. Neither sensory nor motor impairment was present in the lower extremities. MRI revealed a cyst on the right side of the conus medullaris, compressing the spinal cord upward. Clinical signs and symptoms disappeared following surgical resection of the cyst. Histological examination showed that this cyst was lined with a single layer of tall columnar or low cuboidal cells on fibrous connective tissue. The basement membrane was absent in the cyst wall. Reactivity to CAM5.2 and AE1/AE3 anti-keratin antibodies suggested that the cyst was of neuroepithelial origin. No recurrence has been noted 3 years after surgery.
    Journal of Clinical Neuroscience 02/2010; 17(2):272-3. · 1.25 Impact Factor
  • Orthopedics & Traumatology. 01/2010; 59(3):653-655.
  • Bone 06/2009; 44. · 4.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Attention has recently focused on the critical role of inflammatory responses in the tumor stroma that provide favorable conditions for cancer-cell growth and invasion/metastasis. In particular, macrophages recruited into the tumor stroma and activated, known as tumor-associated macrophages, are suggested to promote tumorigenesis. In this study, we examined the effect of a decrease in the number of monocytes/macrophages in peripheral blood and the tumor stroma on the development of bone and muscle metastases by lung cancer cells. Treatment with clodronate encapsulated by liposomes (Cl(2)MDP-LIP) has been developed for the depletion of monocytes/macrophages in an animal model. Subcutaneous administration of Cl(2)MDP-LIP markedly reduced the number of monocytes in peripheral blood, resulting in efficient suppression of both bone metastasis and muscle metastasis when lung cancer HARA-B cells were injected into the left cardiac ventricle of mice. Treatment with Cl(2)MDP-LIP significantly reduced the number of macrophages in tumors and the number of osteoclasts in bone marrow, as well as peripheral monocytes in mice harboring lung cancer cells. In contrast, treatment with an osteoclast-targeting antibiotic, reveromycin A, inhibited bone metastasis by lung cancer cells, but not muscle metastasis. The survival of human macrophages in culture was found to be specifically blocked by Cl(2)MDP-LIP, but not by reveromycin A. Cl(2)MDP-LIP thus exerted antimetastatic effects in both bone and muscle whereas reveromycin A did so only in bone. Liposome-encapsulated bisphosphonate may modulate metastasis through decreasing the number of monocytes/macrophages in both peripheral blood and the tumor stroma, suggesting that tumor-associated macrophages might be suitable targets for antimetastatic therapy.
    Cancer Science 09/2008; 99(8):1595-602. · 3.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Osteoarthritis (OA) is closely related to the function of several inflammatory cytokines. It has been reported that older age is associated with higher serum levels of the inflammatory cytokine IL-18. In the present study, we investigated the long-term role of serum IL-18 in cartilage loss in vivo using a new strain of IL-18 transgenic mouse (Tg) in comparison with wild-type (WT) mice. The IL-18 Tg mouse strain we developed constitutively overproduces soluble mature IL-18 in the lungs but not in other tissues, including joints. These Tg mice showed high levels of serum IL-18, but not IL-1beta. No inflammatory cells, fibrillation or synovitis were observed in the knee joints of either IL-18 Tg or WT mice. However, the cartilage cellularity of the femoral and tibial condyles of IL-18 Tg mice was significantly reduced in comparison with control WT mice. Aggrecan was detected in only a few cells in the deep zone of the articular cartilage of Tg mice. The expression of aggrecan mRNA was also significantly decreased in articular chondrocytes from Tg mice when compared with WT mice. In contrast, endogenous IL-18 mRNA was significantly increased in the chondrocytes of Tg mice in comparison with WT mice. Expression of IFN-gamma was also significantly increased in the Tg mice. Moreover, IL-18 transgene-positive caspase-1-deficient mice showed articular cartilage loss that was independent of endogenous IL-1beta. In cultured chondrocytes isolated from WT mice, the expression of aggrecan mRNA was dosage-dependently suppressed by treatment with recombinant IL-18. In contrast, IL-18 stimulated the expression of mRNA for endogenous IL-18 and IFN-gamma. These results suggest that high levels of serum IL-18 promote the overexpression of endogenous IL-18 in articular chondrocytes, resulting in cartilage loss through suppression of aggrecan synthesis. Thus IL-18 may play an important role in the pathogenesis of articular cartilage loss in osteoarthritis.
    Bone 07/2008; 42(6):1102-10. · 4.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: There is no established optimum treatment for malignant fibrous histiocytoma (MFH) at present, and few MFH cell lines are established. In the present study, we established new MFH cell lines, KHZ-MFH and SFT85-03, and investigated the JAK/STAT (Janus kinase/signal transducer and activator of transcription) signaling pathway. We found that MFH cells secreted high levels of IL-6 and that STAT3 was constitutively activated in these cells. The JAK2 kinase inhibitor, tyrphostin AG490, suppressed the growth of MFH cells and inhibited the secretion of IL-6. Furthermore, blockade of activated STAT3 by forced expression of a cytokine signaling repressor, SOCS3 gene as well as a dominant-negative STAT3 in these cells significantly suppressed their growth. These results indicated that an autocrine mechanism of the JAK/STAT3 signaling pathway could promote the growth of MFH cells and that this pathway could be a therapeutic target of MFH.
    Cancer Letters 02/2006; 231(2):176-84. · 5.02 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The in vivo effects of IL-18 on bone metabolism were investigated by histopathology in IL-18 transgenic mice. Deformed cortical bone and decreased turnover rate of lumbar trabecular bone are consistent with increased expression of IFN-gamma and IL-18 in the bone marrow. Interleukin (IL)-18 has been demonstrated to inhibit osteoclastogenesis in an in vitro co-culture system. We investigated the effects of IL-18 overexpression on bone metabolism by comparing bone characteristics in male IL-18 transgenic (TG) mice, which secrete mature murine IL-18 from their B- and T-cells, and their wildtype littermates (WT). Histopathological analysis revealed that the cortical bone of the femur was thinner and more deformed in IL-18 TG mice. Bone histomorphometry showed that the cortical bone area of the mid-diaphysis of the femur and the trabecular bone volume of the lumbar vertebrae were significantly reduced in IL-18 TG mice. IL-18 TG mice also exhibited significantly fewer osteoclasts and a reduced bone formation rate in the trabecular bones of their lumbar vertebrae. Real-time reverse transcriptase-polymerase chain reaction amplification of bone marrow cell mRNA revealed that interferon (IFN)-gamma mRNA expression was significantly increased, whereas IL-4 mRNA expression was significantly reduced, in IL-18 TG mice. However, the expression ratio of receptor activator of NFkappaB ligand and osteoprotegerin mRNA was not significantly altered. Thus, deformed cortical bone and a decreased turnover rate of lumbar trabecular bone are characteristic of IL-18 TG mice, and these features might be associated with the increased expression of IFN-gamma and IL-18 in the bone marrow.
    Journal of Bone and Mineral Research 07/2003; 18(6):975-83. · 6.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The histological grade of chondrosarcoma correlates well with their clinical behavior and with the patient's survival duration. We have previously demonstrated that p21 was expressed in the hypertrophic chondrocytes of the growth plate. To assess the relationship of p21 (waf1/cip1) to cell differentiation in chondrosarcoma, we examined the p21 expression in 14 cases of chondrosarcoma immunohistochemically and the induction of p21 by insulin-like growth factor-I (IGF-I) during cell differentiation in SW1353 chondrosarcoma cells. p21 immunoreactivity was seen in well-differentiated chondrosarcoma cells and was mutually exclusive with MIB1 reactivity in grade-1 chondrosarcoma. In vitro, the proteoglycan synthesis of SW1353 cells was increased by IGF-I in a dose-dependent manner. However, cell proliferation was not markedly stimulated. Overexpressions of p21 mRNA and p21 protein in SW1353 cells were induced by IGF-I 100 ng/ml. Our results suggested that the p21 expression was directly related to tumor differentiation and that the p21 expression was an important mediator for IGF-I in chondrosarcoma cells.
    Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 04/2002; 440(3):285-90. · 2.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An essential nutrient selenium has been reported to be a potential cancer preventive and inhibitory agent, although no exact mechanism has yet been proposed. Since little is known about the anti-proliferative effect of selenium on osteosarcoma, this issue was addressed in the present study in vitro using three osteosarcoma cell lines, and in vivo using an osteosarcoma transplantable to nude mice. Selenium inhibited the tumor growth in vitro and morphological changes indicative of apoptosis were demonstrated. Osteosarcomas in nude mice were inhibited in growth by selenium with no cytotoxic change in normal tissues. The findings suggested that selenium may offer a novel therapeutic modality for osteosarcoma.
    Journal of Orthopaedic Research 10/2001; 19(5):809-14. · 2.88 Impact Factor