Hiroyuki Yamada

Tsurumi University, Yokohama, Kanagawa, Japan

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Publications (34)51.33 Total impact

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    ABSTRACT: Myofibroma is a benign tumor composed of myoid spindle cells. The prevalence of myofibroma in the oral cavity is very low, with the mandible being the most common site. This report describes an adult case of myofibroma that arose on the mandible and includes magnetic resonance imaging (MRI) and positron emission tomography (PET) findings. On the MRI T1-weighted images, the tumor appeared with signal iso-intensity and was highly and heterogeneously enhanced with contrast material. On the T2-weighted images, it appeared with increased signal intensity. 18 F-fluorodeoxyglucose (FDG)-PET imaging showed abnormal strong accumulation of FDG in the left mandibular region. The tumor was removed by marginal resection of the left mandible under general anesthesia. Histopathological findings revealed that the tumor stroma contained abundant thin-walled vessels. The postoperative course was uneventful, and we found no evidence of recurrence at the postoperative 34-month follow-up.
    World Journal of Surgical Oncology 03/2014; 12(1):69. · 1.09 Impact Factor
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    ABSTRACT: This is the first report to our knowledge of an intramuscular lipoma that arose in the masseter muscle. Excision biopsy under general anaesthesia showed that the mass could easily be separated from the surrounding soft tissues on the lateral side, but was firmly adherent to the muscle on the medial side, so complete excision required resection of part of the masseter. Histopathological examination showed that it was an intramuscular lipoma. Two years and 6 months postoperatively there was no evidence of recurrence.
    British Journal of Oral and Maxillofacial Surgery 01/2014; · 2.72 Impact Factor
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    ABSTRACT: Abstract The objective of this study is to evaluate usefulness of mandibular reconstructions using a custom-made titanium mesh (Ti-mesh) tray and particulate cancellous bone and marrow (PCBM). A consecutive nine patients who underwent mandibular reconstruction were enrolled in this study. They were five men and four women (mean age: 53.9 years). Virtual reality simulation was performed using computer software based on the pre-operative computed tomography data. A 3-dimensional (3-D) skull model was constructed using a 3-D printer. A tray was custom-made from a Ti-mesh sheet bent to adapt to the model. After PCBM harvesting from bilateral posterior ilia, the tray was fixed to the host bone. New bone formation and configuration of the reconstructed mandible were assessed radiologically. Complications were recorded in each patient during the follow-up period. Patients, satisfaction with post-operative facial contour was evaluated using a visual analogue scale (VAS score, range = 0-100). In six of nine patients, excellent new bone formation was recognised and expected results were radiologically achieved. Complications occurred in four patients. These complications included Ti-mesh fracture, Ti-mesh exposure in the oral cavity, and delayed infection. Mean VAS score on patient satisfaction was 77.6. Although the data are preliminary, the results suggest that this method is clinically useful.
    Journal of plastic surgery and hand surgery. 10/2013;
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    ABSTRACT: OBJECTIVE: This study aimed to establish a mouse model in which dental pulp cells (DPCs) could be used as a cell source for the treatment of salivary gland hypofunction. DESIGN: DPCs were isolated from green fluorescent protein (GFP)-expressing mice and were differentiated into dental pulp endothelial cells (DPECs). DPEC behaviour was studied in vitro and in vivo to investigate their capacity to participate in neovascularisation. For in vivo assessment, a combination of DPECs and Matrigel was subcutaneously injected into nude mice. Two weeks after injection, Matrigel plugs were analysed for CD31 and GFP. Furthermore, both submandibular glands of the irradiated mice were injected with DPECs. Eight weeks after irradiation, the effect of DPECs on saliva secretion was evaluated by measuring amounts of saliva secretion. RESULTS: DPECs showed typical endothelial morphology, including a cobblestone appearance. RT-PCR analysis of DPECs showed positive expression of CD31, foetal liver kinase-1, vascular-endothelial-cadherin, vascular endothelial growth factor-A and von Willebrand factor. DPECs reorganised into tube-like structures on Matrigel after 24h in vitro. Positive merged staining for both CD31 and GFP was observed in the tube-like structures, representative of the injected DPECs. The average saliva flow rate in mice treated with DPECs was significantly higher than that observed in mice treated with PBS (P=0.0452). CONCLUSIONS: Our results show that radiation-induced salivary hypofunction is partially reverted following transplantation of DPECs. We established a mouse model in which DPCs could be used as a cell source for the treatment of salivary gland hypofunction.
    Archives of Oral Biology 04/2013; · 1.55 Impact Factor
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    ABSTRACT: In the present study, we investigate the expression profile of the epidermal growth factor receptor family, which comprises EGFR/ErbB1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4 in oral leukoplakia (LP). The expression of four epidermal growth factor receptor (EGFR) family genes and their ligands were measured in LP tissues from 14 patients and compared with levels in 10 patients with oral lichen planus (OLP) and normal oral mucosa (NOM) from 14 healthy donors by real-time polymerase chain reaction (PCR) and immunohistochemistry. Synchronous mRNA coexpression of ErbB1, ErbB2, ErbB3 and ErbB4 was detected in LP lesions. Out of the receptors, only ErbB4 mRNA and protein was more highly expressed in LP compared with NOM tissues. These were strongly expressed by epithelial keratinocytes in LP lesions, as shown by immunohistochemistry. Regarding the ligands, the mRNA of Neuregulin2 and 4 were more highly expressed in OLP compared with NOM tissues. Therefore, enhanced ErbB4 on the keratinocytes and synchronous modulation of EGFR family genes may contribute to the pathogenesis and carcinogenesis of LP.International Journal of Oral Science (2013) 5, doi:10.1038/ijos.2013.10; published online 15 March 2013.
    International Journal of Oral Science 03/2013; 5. · 2.72 Impact Factor
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    ABSTRACT: This case report presents an unusual case of a simple mandibular bone cyst with remarkable tooth resorption. A 52-year-old woman was referred to our clinic for examination of a radiolucent lesion located in the right third mandibular molar region. The lesion could not be identified on panoramic radiograph at 6 years ago. Imaging examinations demonstrated a relatively well demarcated radiolucent lesion in the right mandible with marked resorption of the third molar. Based on the tentative diagnosis of an intraosseous benign tumor, biopsy was performed. The lesion was a simple bone cavity containing sanguineous fluid with no evidences of a cystwall lining or tumoral tissue. Intraoperative diagnosis was a simple bone cyst, and the lesion including the remained third molar was carefully removed. Histopathologically, thin fibrous connective tissue without epithelial cover was observed on the surface of the bony wall. The histopathologic findings were consistent with those of a simple bone cyst. However, myxofibromatous connective tissue and woven bone were observed only on the surface of the resorbed dental hard tissue. This case may be associated with the fibro-osseous lesion to some degree. One year later, complete healing was observed.
    Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology. 01/2013; 25(1):93–96.
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    ABSTRACT: Stem cell-based therapy has been proposed as a promising strategy for regenerating tissues lost through incurable diseases. Side population (SP) cells have been identified as putative stem cells in various organs. To examine therapeutic potential of SP cells in hypofunction of exocrine glands, SP cells isolated from mouse exocrine glands, namely, lacrimal and salivary glands, were transplanted into mice with irradiation-induced hypofunction of the respective glands. The secretions from both glands in the recipient mice were restored within 2 months of transplantation, although the transplanted cells were only sparsely distributed and produced no outgrowths. Consistent with this, most SP cells were shown to be CD31-positive endothelial-like cells. In addition, we clarified that endothelial cell-derived clusterin, a secretory protein, was an essential factor for SP cell-mediated recovery of the hypofunctioning glands because SP cells isolated from salivary glands of clusterin-deficient mice had no therapeutic potential, whereas lentiviral transduction of clusterin restored the hypofunction. In vitro and in vivo studies showed that clusterin had an ability to directly inhibit oxidative stress and oxidative stress-induced cell damage. Thus, endothelial cell-derived clusterin possibly inhibit oxidative stress-induced hypofunction of these glands.
    Stem Cells 07/2012; 30(9):1925-37. · 7.70 Impact Factor
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    ABSTRACT: Solitary fibrous tumor (SFT) is an uncommon spindle-cell mesenchymal tumor of probable fibroblastic derivation that most often occurs in the pleura, where it is typically benign. This report describes a case of a large SFT that arose in the buccal space, and includes computerized tomography, magnetic resonance imaging, and positron emission tomography (PET) findings. (18)F-Fluorodeoxyglucose (FDG) PET axial imaging showed weak abnormal accumulation of FDG in the left buccal region. The tumor was located behind the posterior wall of the maxilla, adjacent to the medial aspect of the coronoid process and was compressed between the coronoid and maxillary alveolar processes. We resected it with the use of a transoral approach in combination with coronoidectomy. Coronoidectomy was chosen because it facilitated safe removal of the tumor by improving its visibility and providing enough working space to resect it through a transoral approach.
    Oral surgery, oral medicine, oral pathology and oral radiology. 07/2012; 114(1):e9-e14.
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    ABSTRACT: Clenbuterol, a β(2) -adrenergic agonist, increases the hypertrophy of skeletal muscle. Insulin-like growth factor (IGF) is reported to work as a potent positive regulator in the clenbuterol-induced hypertrophy of skeletal muscles. However, the precise regulatory mechanism for the hypertrophy of skeletal muscle induced by clenbuterol is unknown. Myostatin, a member of the TGFβ super family, is a negative regulator of muscle growth. The aim of the present study is to elucidate the function of myostatin and IGF in the hypertrophy of rat masseter muscle induced by clenbuterol. To investigate the function of myostatin and IGF in regulatory mechanism for the clenbuterol-induced hypertrophy of skeletal muscles, we analysed the expression of myostatin and phosphorylation levels of myostatin and IGF signaling components in the masseter muscle of rat to which clenbuterol was orally administered for 21 days. Hypertrophy of the rat masseter muscle was induced between 3 and 14 days of oral administration of clenbuterol and was terminated at 21 days. The expression of myostatin and the phosphorylation of smad2/3 were elevated at 21 days. The phosphorylation of IGF receptor 1 (IGFR1) and akt1 was elevated at 3 and 7 days. These results suggest that myostatin functions as a negative regulator in the later stages in the hypertrophy of rat masseter muscle induced by clenbuterol, whereas IGF works as a positive regulator in the earlier stages. Copyright © 2012 John Wiley & Sons, Ltd.
    Cell Biochemistry and Function 06/2012; · 1.85 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the effect of stereotactic radiosurgery on local control and organ preservation in cases of primary head and neck cancer. In this retrospective study, 14 patients with a mean age of 73 years were treated between March 2006 and September 2007 with stereotactic radiosurgery for the management of primary head and neck cancer. The patients had biopsy confirmation of disease before treatment and all patients were confirmed with squamous cell carcinoma. The staging consisted of T2 (5 cases), T3 (3 cases), T4 (6 cases), N0 (13 cases), and N1 (1 case). Marginal doses were 3,500 to 4,200 cGy in 3 or 5 fractions. The outcome was assessed according to Response Evaluation Criteria in Solid Tumors criteria based on magnetic resonance imaging and positron emission tomography/computed tomography. Significant tumor reduction was noted at the third month of follow-up with 5 complete responses and 9 partial responses. At a mean follow-up of 36 months (range, 14-40 mo) the local control and overall survival rates were 71.4% (10/14) and 78.6% (11/14), respectively. These results show the feasibility of using stereotactic radiosurgery for primary head and neck cancer and its potential benefit in local control and organ preservation.
    Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 07/2011; 70(2):461-72. · 1.58 Impact Factor
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    ABSTRACT: This study aimed to investigate the roles of the epidermal growth factor receptor (EGFR) family members and their ligands in oral lichen planus (OLP). The expressions of 4 EGFR-like receptors and 6 EGF-like ligands were measured in OLP tissues from 10 patients and compared with the levels in normal oral mucosa (NOM) from 10 healthy donors. Of the receptors, only EGFR mRNA and protein were more highly expressed in OLP compared with NOM tissues. Regarding the ligands, the mRNAs of amphiregulin (AREG), epiregulin (EREG), and heparin-binding EGF-like growth factor (HB-EGF) were more highly expressed in OLP compared with NOM tissues. These ligands were strongly expressed by infiltrating lamina propria lymphocytes as well as epithelial keratinocytes in OLP lesions, as shown by immunohistochemistry. The enhanced EGFR expression on the keratinocytes in OLP lesions and the up-regulation of EGF-like ligands in keratinocytes and infiltrating mononuclear cells could contribute to the carcinogenesis and pathogenesis of OLP.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 10/2010; 110(6):748-54. · 1.50 Impact Factor
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    ABSTRACT: For many years, gingival tumors of what appear to be peripherally located intraosseous ameloblastoma (IA) arising from the alveolar bone surface have often been confused with peripheral ameloblastoma (PA) causing resorption of the underlying bone. We analyzed a series of five cases of ameloblastoma that demonstrated a combined PA and IA architecture. The tumor commonly involved the anterior-premolar area, mostly in the maxilla and mainly in middle-aged men. The clinical presentation was an exophytic gingival mass inferior to which was a small bone defect. The predominant extraosseous component showed a papillary gross surface, reflecting the histologic proof of fusion between the submucosal tumor and the surface epithelium. In addition to the PA-like growth pattern, common to all was the presence of neoplastic destruction of the alveolar process, corresponding to an associated radiolucent lesion. This restrained component was acceptable as IA. In two cases, recurrence was observed deep in the alveolar bone with no involvement of the gingiva. These tumors appear to be IA that arose from the marginal alveolar bone and grew preferentially in the gingiva, forming a PA-like appearance. From diagnostic, therapeutic and prognostic points of view, this type of IA should not be confused with PA.
    Head and Neck Pathology 09/2010; 4(3):192-7.
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    ABSTRACT: This study aimed to elucidate the differences in antitumor immune responses between primary tumors and metastatic regional lymph nodes in head and neck squamous cell carcinoma (HNSCC). The clonality of tumor-infiltrating lymphocytes in tissue specimens from 17 HNSCC patients was examined regarding their T-cell receptor (TCR) repertoires and their complementary determining region 3 (CDR3) size spectratyping. Cytokine expression profiles and T-cell phenotypes also were measured by using real-time quantitative polymerase chain reaction. The host immune responses to HNSCC cells, reflected by the TCR repertoire, differed between primary tumors and metastatic lymph nodes. CD8+-T cells and T helper type 1 (TH1)/T cytotoxic 1 (TC1) cell cytokine production in metastatic and nonmetastatic lymph nodes were similar. The antitumor immune response to HNSCC cells changes during lymph node metastasis, and HNSCC cells can escape the cytotoxic immune responses mediated by CD8+-T cells and TH1/TC1 cells. These results suggest that lymph node metastasis might be associated with changes in the nature of the primary tumor antigens.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 09/2010; 110(3):341-50. · 1.50 Impact Factor
  • Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 08/2010; 110(2):140-4. · 1.50 Impact Factor
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    ABSTRACT: Objective This study aimed to explore the risk factors of poor clinical outcome of visually guided irrigation (VGIR) in patients with chronic closed lock (CCL) of the temporomandibular joint (TMJ).
    Asian Journal of Oral and Maxillofacial Surgery 01/2010; 22(3):133-137.
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    ABSTRACT: The aim of this study is to examine the effect of stereotactic radiosurgery (SRS) in the treatment of advanced, recurrent lesions for head and neck carcinoma both with and without lymph node involvement. Between April 2006 and July 2007, 22 patients (mean age 67 years) with advanced, recurrent head and neck carcinoma were treated with stereotactic radiosurgery. All of the patients except one had biopsy confirmed disease prior to stereotactic radiosurgery. Patients included 3 rT2, 8 rT3, and 9 rT4; 8 of the patients had lymph node metastases. Marginal SRS doses were 20-42 Gy delivered in two to five fractions. Starting one month after SRS, all patients received S-1 oral chemotherapy for one year. At an overall median follow-up of 24 months (range, 4-39 months), for the 14 locally recurrent patients without lymph node metastases, 9 patients (64.3%) had a complete response (CR), 1 patient (7.1%) had a partial response (PR), 1 patient (7.1%) had stable disease (SD), and 3 patients (21.4%) had progressive disease (PD). For the 8 patients with lymph node metastases, 1 patient with a single retropharyngeal (12.5%) had CR; the remaining 7 patients (87.5%) all progressed. Nine patients have died from their cancer. The overall actuarial 2-year survival for the patients with and without lymph node metastases is 12.5% and 78.6%, respectively. These results show the benefit of stereotactic radiosurgery salvage treatment for advanced, recurrent lesions, without lymph node metastases in previously irradiated head and neck cancer.
    Radiation Oncology 01/2010; 5:51. · 2.11 Impact Factor
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    ABSTRACT: Reactive oxygen species (ROS) are believed to be involved in radiation-induced xerostomia, and the application of antioxidants may be a promising method for treating patients suffering from salivary gland dysfunction. In this study, we examined the ability of the antioxidant superoxide dismutase (SOD) to restore radiation-induced salivary gland dysfunction using a mouse model of radiation-induced salivary gland hypofunction and ultraviolet B (UVB)-irradiated human salivary gland cells. We administered lecithinized SOD (PC-SOD) prior to and after irradiation and measured the amount of saliva secreted. To confirm ROS generation, flow cytometry was performed using an oxidant-sensitive fluorescent dye, dihydroethidium, and CM-H(2)DCFDA. While no significant decrease in saliva secretion was observed after irradiation in the mice that were treated with PC-SOD, a significant reduction in saliva secretion was noted in the irradiated mice that were not treated with PC-SOD. Furthermore, flow cytometry clearly revealed that PC-SOD eliminated superoxide (O(2)(-)) induced by UVB radiation. These results suggested that PC-SOD may protect against exocrine gland dysfunction induced by radiation, presumably by rapidly converting O(2)(-) to hydrogen peroxide. We believe that our results may advance the potential application of antioxidants for the prevention of ROS-induced xerostomia.
    Radiation Research 10/2009; 172(3):331-8. · 2.70 Impact Factor
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    Fumio Ide, Kenji Mishima, Hiroyuki Yamada, Ichiro Saito
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    ABSTRACT: There is a considerable variation in the histologic subtype of epithelial malignancies among carcinoma ex pleomorphic adenomas (CXPA) and virtually any known carcinoma entity can develop. To our knowledge, adenoid cystic carcinoma (AdCC) ex PA is quite rare despite the fact that de novo AdCC is the fourth most common salivary gland malignancy. We describe a new case of AdCC ex PA in the parotid gland of a 62 year-old woman. In our patient, there was a short interval of time between parotidectomy and local recurrence and rapid development of distant metastases. Although most of the reported cases are considered low-grade, evidence is presented here that AdCC can take the form of a high-grade malignancy in PA.
    Head and Neck Pathology 07/2009; 3(2):159-62.
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    ABSTRACT: This study reports on 15 mandibular reconstructions using the Dumbach Titan Mesh-System and particulate cancellous bone and marrow harvested from bilateral posterior ilia. All cases showed segmental defects. Eleven cases involved patients with malignant tumor. Six patients had received irradiation of 40-50 Gy. Reconstructions were performed immediately in 1 patient and secondarily in the remaining 14 patients. In 13 cases, mandibles were successfully reconstructed. Of these 13 patients, 9 reconstructions were completed without complications, whereas the other 4 cases showed complications. In 2 cases, reconstruction failed completely. Overall success rate was 87%. Statistical analysis revealed the extent of mandibular defect, but not malignancy of the original disease or radiotherapy of <or=50 Gy, as a significant factor in the occurrence of postoperative complications. Although no significant correlation was identified, cases in which mandibular continuity was lost at the time of reconstruction tended to show a higher postoperative complication rate. These results suggest that for the management of patients with malignant disease, resected mandible and soft tissue should be properly reconstructed using the metal plate and soft tissue flap at the time of cancer ablation surgery to reduce postreconstructive complications. Preoperative fabrication of the titanium mesh using a 3-dimensional skull model is expected to improve surgical outcomes.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 02/2009; 107(4):e1-8. · 1.50 Impact Factor
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    ABSTRACT: The usefulness of a night guard for nocturnal xerostomia was investigated. A controlled clinical trial was conducted, and the primary outcome measure was the satisfaction with the night guard in subjective improvement of the sensation of nocturnal dryness. The night guard device was fabricated with a 1.5-mm-thick ethylene vinyl acetate sheet, which covered the dental arch and the hard palate, and did not possess a reservoir for retaining a saliva substitute. Following completion of 2-week treatment, substantial improvement was reported by the treatment group compared with the control group (P = .025). The posttreatment VAS value was significantly decreased compare with that of pretreatment period in sensation of oral dryness (P = .0295), thirstiness (P = .0012), and burning sensation of the tongue (P = .0371) in the treatment group The application of a night guard is suggested to be a useful and simple method for the management of nocturnal xerostomia.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 08/2008; 106(3):e11-4. · 1.50 Impact Factor

Publication Stats

119 Citations
51.33 Total Impact Points

Institutions

  • 2004–2014
    • Tsurumi University
      • • Department of Oral and Maxillofacial Surgery
      • • School of Dental Medicine
      • • Department of Pathology
      Yokohama, Kanagawa, Japan
  • 2006
    • Center For Oral & Maxillofacial Surgery
      Georgia, United States