Yukihide Iwamoto

Kyushu University, Hukuoka, Fukuoka, Japan

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Publications (595)1592.77 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Epithelioid angiosarcoma is a rare variant of angiosarcoma, and is characterized by an epithelioid morphologic appearance that mimics carcinoma. These tumors usually arise in extraskeletal sites; origination in bone is rare.
    World Journal of Surgical Oncology 09/2014; 12(1):281. · 1.09 Impact Factor
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    ABSTRACT: Marked neurological deterioration within a few days of traumatic spinal cord injury, known as subacute posttraumatic ascending myelopathy, is rare. Although several hypotheses regarding the pathogenesis of this condition have been proposed, the details remain elusive.
    The spine journal: official journal of the North American Spine Society 09/2014; · 2.90 Impact Factor
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    ABSTRACT: Objectives. A major signaling pathway that regulates cellular aging is the Insulin/IGF-1/Pl3k/Akt/forkhead-box class O (FOXO) transcription factor axis. Previously, we observed that FOXO factors are dysregulated in aged and OA cartilage. The objective of this study was to investigate the impact of downregulated FOXOs on chondrocytes.Methods. Small interference RNAs (siRNAs) for FOXO1 and FOXO3 were transfected into human articular chondrocytes. Cell viability following treatment with the oxidant tert-Butyl hydroperoxide (t-BHP) was measured by MTT assay. Caspase-3/7 activation and apoptotic cell were examined. Gene and protein expression of antioxidant proteins and autophagy related proteins and changes in inflammatory mediators following treatment with IL-1β were analyzed. Cells transfected with FOXO plasmids were also analyzed.Results. Cell viability was significantly reduced by siFOXO under treatment with t-BHP. Apoptosis accompanied by caspase activation was significantly induced in FOXO-siRNA transfected chondrocytes. Knock-down of FOXO1 and FOXO1+3 resulted in significant reductions of GPX-1, catalase, LC3, Beclin1, and SIRT1 proteins following treatment with t-BHP. In contrast, constitutive active form of FOXO 3 increased cell viability while inducing GPX1, Beclin1, and LC3 in response to t-BHP. Expression and production of ADAMTS-4 and Chemerin were significantly increased in FOXO-siRNA transfected chondrocytes.Conclusions. Reduced expression of FOXO transcription factors in chondrocytes increased susceptibility to cell death induced by oxidative stress. This was associated with reduced antioxidant proteins and autophagy related proteins. Our data provide evidence for a key role of FOXO transcription factors as regulators of chondrocyte oxidative stress resistance and tissue homeostasis. © 2014 American College of Rheumatology.
    Arthritis & Rheumatology. 09/2014;
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    ABSTRACT: We aimed to clarify whether the coronal alignment after medial unicompartmental knee arthroplasty (UKA) is predictable using preoperative full-length valgus stress radiography.
    Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 08/2014;
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    ABSTRACT: The aim of the study was to assess the degree and location of the reparative process in early osteonecrosis of the femoral head on the basis of single-photon emission computed tomography/computed tomography (SPECT/CT) with technetium-99m hydroxymethylene diphosphonate.
    Nuclear Medicine Communications 07/2014; · 1.38 Impact Factor
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    ABSTRACT: To investigate the clinical outcomes and imaging features of malignant peripheral nerve sheath tumors (MPNSTs) presenting as spinal dumbbell tumors.
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    ABSTRACT: The aim of this study was to compare the levels of bone and cartilage metabolism markers in the synovial fluid of the hip joint between patients with secondary OA due to osteonecrosis of the femoral head (ONFH), rapidly destructive arthrosis (RDA) and developmental dysplasia of the hip (DDH).
    Rheumatology (Oxford, England) 06/2014; · 4.24 Impact Factor
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    ABSTRACT: The aim of the present study was to clarify whether varus-valgus laxities under static stress in extension, femoral condylar lift-off during walking, and patient-reported outcomes after total knee arthroplasty (TKA) were correlated with each other.
    Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 06/2014;
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    ABSTRACT: A randomized Phase II/III trial was planned to commence in March 2014. Perioperative chemotherapy with adriamycin plus ifosfamide is the current standard treatment for T2bN0M0 high-grade non-round cell soft tissue sarcoma. The purpose of this study is to confirm the non-inferiority of perioperative chemotherapy with gemcitabine and docetaxel to adriamycin plus ifosfamide for patients with T2bN0M0 or any TN1M0 non-round cell soft tissue sarcoma in the extremities and body wall. A total of 140 patients will be accrued from 28 Japanese institutions over 6 years. The primary endpoint in the Phase II part is the proportion of completion of pre-operative chemotherapy without progressive disease and overall survival in the Phase III part. The secondary endpoints are progression-free survival, response rate of pre-operative chemotherapy, pathological response rate, proportion of preservation of diseased limbs, disease control rate and proportion of adverse events. This trial has been registered in the UMIN Clinical Trials Registry as UMIN000013175 [http://www.umin.ac.jp/ctr/index.htm].
    Japanese Journal of Clinical Oncology 06/2014; · 1.90 Impact Factor
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    ABSTRACT: Study Design Retrospective cohort study. Objectives The mechanism underlying the pain relief observed following balloon kyphoplasty (BKP) to vertebral compression fractures is reported to involve stabilization of the fractured vertebrae. However, whether fixation of the vertebrae was achieved immediately after BKP has not been investigated. The purpose of this study was to assess fixation of the vertebrae immediately after BKP and whether the instability was related to visual analog scale (VAS) scores. Methods Thirty-eight patients with vertebrae that were evaluated on lateral roentgenkymography within 1 week after BKP were recruited. Instability was defined as a cleft observed between the cement and end plate of the vertebra in the supine position that disappeared in the sitting position, and the posterior wall height of the vertebra was reduced in the sitting position. Results Instability of the vertebrae immediately after BKP was observed in 17 cases. VAS scores improved in all cases, and no significant differences were observed with or without instability. Conclusions The mechanism of rapid pain relief following BKP was not strong fixation but some degree of stabilization or other factors. We suggest that more research is needed about the mechanism of pain relief following BKP in the future.
    Global spine journal. 06/2014; 4(2):89-92.
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    ABSTRACT: Ischio-pubic stress fracture is one of the potential complications after peri-acetabular osteotomy (PAO) in patients with hip dysplasia. The purpose of this study was to examine the prevalence of and risk factors for ischio-pubic fractures following PAO.
    International Orthopaedics 05/2014; · 2.32 Impact Factor
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    ABSTRACT: The Akt/mammalian target of rapamycin (mTOR) pathway plays important roles in modulating cellular function in response to extracellular signals such as growth factors and cytokines. The Akt/mTOR signaling pathway is activated in certain kinds of sarcomas. Myxofibrosarcoma is a soft tissue sarcoma, characterized by abundant myxoid stroma and frequent local recurrence. Here, we conducted a large-scale examination of the clinicopathological and activation statuses of the Akt/mTOR pathways in myxofibrosarcoma. The phosphorylation status of Akt, mTOR, S6 ribosomal protein, and the eukaryotic translation initiation factor 4E-binding protein, and mitogen-activated protein kinase were assessed by immunohistochemistry in 101 formalin-fixed, paraffin-embedded samples, including 68 primary tumors in myxofibrosarcoma. Immunohistochemical expressions were confirmed by Western blotting with 20 frozen samples, which were paired with normal tissue samples. PIK3CA and AKT1 gene mutations were also analyzed using 12 primary tumor frozen samples. Immunohistochemically, phosphorylations of Akt, mTOR, S6 ribosomal protein, 4E-binding protein, and mitogen-activated protein kinase 1/2 were observed in 64.7%, 45.6%, 42.6%, 63.2%, and 64.7% of samples. Phosphorylated Akt/mTOR pathway proteins were correlated with one another and were also correlated with the phosphorylation of these proteins in the concordant recurrent tumors. Immunoblotting showed a high degree of phosphorylation in tumor samples, compared with that in normal tissue samples. Activation of the Akt/mTOR pathway was correlated with histologic grade and tumor progression. Mutational analysis failed to reveal any PIK3CA or AKT1 mutations around the hot spots. Activation of the Akt/mTOR pathway was associated with histologic malignancy and tumor progression in primary and recurrent myxofibrosarcoma.
    Human pathology 05/2014; 45(5):984-93. · 3.03 Impact Factor
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    ABSTRACT: If the aperture of the oval-shaped femoral tunnel on the lateral cortex becomes bigger than half the size of the cortical button, the risk of fixation failure increases. This study investigated the effect of the location of the entry point and diameter of the femoral tunnel on the length of the major axis of the tunnel aperture in anterior cruciate ligament (ACL) reconstruction using an outside-in technique. Simulation of femoral tunnel drilling was performed on computed tomography (CT)-based 3-dimensional (3D) bone models obtained from 40 participants. The tunnel connected the center of the ACL footprint and various points on the lateral femoral surface. The diameter of the tunnel was set at 4.2 mm, 5.2 mm, or 6 mm, depending on the commercially available outside-in surgical systems (Arthrex, Naples, FL and Smith & Nephew, Andover, MA). The length of the major axis of the oval-shaped aperture on the lateral femoral surface was measured. When the tunnel was introduced at 2 cm from the lateral epicondyle in a 45° anteroproximal direction, the major axis was lengthened to 130.7% ± 9.0% (P < .001) of the tunnel diameter, and it was more than 6.5 mm in 65% of participants in whom a 5.2-mm-diameter tunnel was drilled. When the entry point was 3 cm from the lateral epicondyle, 60% of participants had an oval-shaped aperture with a major axis of more than 6.5 mm, even though the diameter of the tunnel was only 4.2 mm. The risk of fixation failure of a cortical button increases if the entry point for drilling is 2 cm or further from the lateral epicondyle and the tunnel diameter is more than 5 mm. This study indicates the potential risk of cortical button fixation failure caused by an oval tunnel aperture on the lateral femoral surface in ACL reconstruction using the outside-in technique.
    Arthroscopy The Journal of Arthroscopic and Related Surgery 05/2014; · 3.10 Impact Factor
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    ABSTRACT: Although a substantial percentage of patients with rheumatoid arthritis (RA) experience low back pain, the characteristics of lumbar spine pathology in RA patients has been poorly investigated. In our institutions, lumbar spine radiographs indicated scoliosis in 26 patients. The present study aimed to clarify the characteristics of lumbar scoliosis in RA patients. This is a retrospective study of 26 RA patients with lumbar scoliosis. Patient characteristics such as disease duration, disease stage and class according to Steinbrocker's classification, and medication for RA and osteoporosis were reviewed. Radiologic evaluation of scoliosis was performed at two different time points by measuring Cobb angles. The progression of scoliosis per year was calculated by dividing the change in Cobb angles by the number of years. Apical vertebral rotation, lateral listhesis, and the level of the intercrestal line at the first observation were also measured. The correlation between different factors and changes in the Cobb angles per year was analyzed. Majority of the patients had a long disease duration and were classified as stage 3 or 4 according to Steinbrocker's classification. During the observation period, most patients were treated with glucocorticoids. Unlike the previous studies on degenerative scoliosis, apical vertebral rotation, lateral listhesis, and the level of the intercrestal line at initial observation were not significantly related to the progression of scoliosis. Initial Cobb angles were inversely related to the progression of scoliosis. Patients who were treated with bisphosphonates showed slower progression of scoliosis. Our results indicate that the characteristics of lumbar scoliosis in RA patients differ from those of degenerative lumbar scoliosis. Bone fragility due to the long disease duration, poor control of disease activity, and osteoporosis is possibly related to its progression.
    Journal of Orthopaedic Surgery and Research 04/2014; 9(1):30. · 1.01 Impact Factor
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    ABSTRACT: IL-12, which is produced in response to intracellular bacteria, such as Listeria monocytogenes, promotes the development of pathogen-specific Th1 cells that play an important role in host defense. However, it has also been known that CD44(high) memory-phenotype CD4 T cells with Th1 functions naturally occur in naive mice, and that lymphopenia-induced proliferation of naive CD4 T cells generates memory-phenotype CD4 T cells with Th1 functions, although their differentiation mechanism and contribution to host defense are unclear. In this study, we analyzed the development and the functions of the different subsets of Th1 cells by using mice lacking tyrosine kinase 2 (Tyk2), a member of the Janus kinase family critically involved in IL-12 signaling. In contrast with the case of conventional Ag-specific Th1 cells, the development of naturally occurring Th1 cells was not impaired in Tyk2-deficient mice. In addition, Th1 cells were normally generated from Tyk2-deficient naive CD4 T cells via lymphopenia-induced proliferation. Nevertheless, all these Th1 subsets, including conventional Ag-induced Th1 cells, produced IFN-γ in response to IL-12 in a Tyk2-dependent manner. Importantly, such Tyk2-dependent bystander IFN-γ production of any Th1 subsets conferred early protection against L. monocytogenes infection. Thus, Tyk2-mediated IL-12 signaling is differentially required for the development of different Th1 cell subsets but similarly induces their bystander IFN-γ production, which contributes to innate host defense against infection with intracellular bacteria.
    The Journal of Immunology 04/2014; · 5.52 Impact Factor
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    ABSTRACT: Late segmental collapse after internal fixation for femoral neck fracture is the phenomenon observed in post-traumatic osteonecrosis of the femoral head (ON), which has generally been reported to occur over a year or more after internal fixation. Subchondral insufficiency fracture of the femoral head (SIF) has also been recognized to cause femoral head collapse, however, only two cases of SIF after internal fixation for femoral neck fracture have been reported. We report a case with femoral head collapse observed 5 months after internal fixation for femoral neck fracture, which was histopathologically diagnosed as SIF. Clinically, differentiating SIF from ON is important because some cases of SIF have been reported to heal without surgical treatments. The timing of femoral head collapse after femoral neck fracture may be different between SIF and post-traumatic ON.
    Skeletal Radiology 02/2014; · 1.74 Impact Factor
  • Journal of Orthopaedic Science 02/2014; · 0.96 Impact Factor
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    ABSTRACT: Stem version is not always equivalent to femoral neck version (native version) in cementless total hip arthroplasty (THA). We therefore examined the discrepancy of version between the native femoral neck and stem using pre- and postoperative computed tomography (CT), the level of the femur where the canal version most closely fit the stem version, and the factors influencing version discrepancy between the native femoral neck and stem. A total of 122 hips in 122 patients who underwent primary THA using a metaphyseal-fit stem through the postero-lateral approach were included. Pre- and postoperative CT images were utilized to measure native and stem version, and the version of the femoral canal at four levels relative to the lesser trochanter. The mean native and stem versions were 28.1 ± 11.0° and 38.0 ± 11.2°, respectively, revealing increased stem version with a mean difference of 9.8° (p < 0.0001). A total of 84 hips (68.9 %) revealed an increase in version greater than 5°. Femoral canal version at the level of the lesser trochanter most closely approximated that of stem version. Among the factors analysed, both univariate and multivariate analysis showed that greater degrees of native version and anterior stem tilt significantly reduced the version discrepancy between the native femoral neck and stem version. Since a cementless stem has little version adjustability in the femoral canal, these findings are useful for surgeons in preoperative planning and to achieve proper component placement in THA.
    International Orthopaedics 02/2014; · 2.32 Impact Factor
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    ABSTRACT: In total knee arthroplasty (TKA), a high soft-tissue tension in extension at the time of operation would cause a post-operative flexion contracture. However, how tight the extension gap should be during surgery to avoid a post-operative flexion contracture remains unclear. The hypothesis is that some laxity in the intraoperative extension gap is necessary to avoid the post-operative flexion contracture. A posterior-stabilized TKA was performed for 75 osteoarthritic knees with a varus deformity. The intraoperative extension gap was measured using a tensor device that provides the gap length and the angle between the femoral component and the tibial cut surface. The medial component gap was defined as the gap calculated by subtracting the selected thickness of the tibial component, including the polyethylene liner, from the extension gap at the medial side. Then, the patients were divided into three groups according to the medial component gap, and post-operative extension angle measured 1 year after the surgery was compared between each groups. One year post-operatively, a flexion contracture of more than 5° was found in 0/34 patients when the medial component gap was more than 1 mm, in 2/26 (8 %) patients when the gap was between 0 and 1 mm, and in 3/15 (20 %) patients when the gap was <0 mm. Three factors were associated significantly with the post-operative extension angle: age, preoperative extension angle, and medial component gap. The intraoperative extension gap is related to the post-operative extension angle. Surgeons should leave more than 1-mm laxity after the implantation to avoid the post-operative flexion contracture. As a clinical relevance, this study clarified the optimal extension gap to avoid the post-operative flexion contracture. Prospective comparative study, Level II.
    Knee Surgery Sports Traumatology Arthroscopy 01/2014; · 2.68 Impact Factor
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    ABSTRACT: The purpose of this study was to assess the differences in bone tunnel apertures between the trans-accessory medial portal (trans-AMP) technique and the transtibial (TT) technique in double-bundle anterior cruciate ligament reconstruction. The extent of ovalization and the frequency of overlap of the two tunnel apertures were compared. The simulation of femoral tunnel drilling with the TT and the trans-AMP techniques was performed using three-dimensional computer aided design models from two volunteers. The incidence angle of drilling against the intercondylar wall, the femoral tunnel position, the ovalization, and the overlap were analyzed. The aperture and location of the tunnels were also examined in real anterior cruciate ligament reconstruction cases (n=36). The surgical simulation showed that a lower drill incident angle induced by the TT technique made the apertures of two tunnels more ovalized, located anteromedial tunnels in a shallower position to prevent posterior wall blow out, and led to a higher frequency of tunnel overlap. The trans-AMP group had tunnel places within the footprint and had less ovalization and overlap. The results of analysis for tunnels in the clinical cases were consistent with results from the surgical simulation. In the TT technique, the shallow anteromedial tunnel location and more ovalized tunnel aperture can lead to a higher frequency of tunnel overlap. Compared with the TT technique, the trans-AMP technique was more useful in preparing femoral tunnels anatomically and avoiding tunnel ovalization and overlapping in double-bundle anterior cruciate ligament reconstruction.
    Open Access Journal of Sports Medicine 01/2014; 5:65-72.

Publication Stats

7k Citations
1,592.77 Total Impact Points


  • 1989–2014
    • Kyushu University
      • • Department of Orthopaedic Surgery
      • • Division of Host Defense
      • • Department of Anatomic Pathology
      • • Faculty of Engineering
      • • Faculty of Medical Sciences
      Hukuoka, Fukuoka, Japan
  • 2013
    • The Scripps Research Institute
      • Department of Molecular and Experimental Medicine
      La Jolla, California, United States
  • 2007–2013
    • University of Florida
      • Department of Mechanical and Aerospace Engineering
      Lake Alfred, FL, United States
  • 2012
    • Kyoto University
      • Department of Orthopaedic Surgery
      Kyoto, Kyoto-fu, Japan
  • 2003–2009
    • Otto-von-Guericke-Universität Magdeburg
      • Faculty of Medicine and University Clinic Magdeburg
      Magdeburg, Saxony-Anhalt, Germany
    • Kitasato University
      • Department of Orthopedic Surgery
      Edo, Tōkyō, Japan
  • 2002–2009
    • National Institutes of Health
      • Laboratory of Cell and Developmental Biology
      Bethesda, MD, United States
    • Kyushu Sangyo University
      Hukuoka, Fukuoka, Japan
  • 2006–2008
    • Hospital for Special Surgery
      New York City, New York, United States
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States
    • Sun Yat-Sen University
      • Department of Orthopaedic Surgery
      Guangzhou, Guangdong Sheng, China
  • 2006–2007
    • Osaka City University
      • Department of Public Health
      Ōsaka, Ōsaka, Japan
  • 2005–2006
    • Keio University
      • Department of Physiology
      Tokyo, Tokyo-to, Japan
  • 2000–2004
    • National Hospital Organization Kyushu Cancer Center
      Hukuoka, Fukuoka, Japan
  • 2001–2003
    • Kyushu Rosai Hospital
      Kitakyūshū, Fukuoka, Japan
    • Fukuoka University
      • Department of Orthopaedic Surgery
      Fukuoka-shi, Fukuoka-ken, Japan