Biomedical subjects

Takahiko Shibahara

Publications and source records attributed to Takahiko Shibahara.

At least 19 recordsLinked to original sources

PubMed2006

Establishment of a murine model of bone invasion by oral squamous cell carcinoma.

This study examines the establishment an animal model of bone invasion by oral squamous cell carcinoma to clarify the mechanisms of osteoclast-mediated bone invasion. C(3)H/HeN mice were inoculated with SCCVII cells into the masseter region. At the end of week 3, all surviving mice were sacrificed and analyzed by three-dimensional imaging using micro-computed tomography, histopathological observation using Hematoxylin-Eosin staining and Tartrate-Resistant Acid Phosphatase staining, and confirmation of mRNA expression of the osteoclast-related cytokines IL-6, TNF-alpha, and PTHrP. SCCVII cells rapidly multiplied in the masseter muscle of the mice. Bone invasion was evident only in the SCCVII transplanted group on micro-computed tomography. The histopathologic findings obtained with H-E and TRAP staining indicated that the tumor cells in the mandible of all animals of the SCCVII transplanted group exhibited funicular invasion and presented a serrated pattern of bone resorption. The mRNA expression of IL-6, PTHrP, and TNF-alpha increased as the control decreased. SCCVII cells were highly invasive into mandibular bone in C(3)H/HeN mice. This model was similar to the invasion of human oral cancer into maxillary and mandibular bone. Our mandibular invasion model may provide a powerful new modality for the diagnosis and treatment of oral cancer with bone invasion.

Animals↗

PubMed2006

Enhancement of SPHK1 in vitro by carbon ion irradiation in oral squamous cell carcinoma.

PURPOSE: The purpose of this study was to assess the gene expression changes in oral squamous cell carcinoma (OSCC) cells after carbon ion irradiation. METHODS AND MATERIALS: Three OSCC cell lines (HSC2, Ca9-22, and HSC3) were irradiated with accelerated carbon ion beams or X-rays using three different doses. The cellular sensitivities were determined by clonogenic survival assay. To identify genes the expression of which is influenced by carbon ion irradiation in a dose-dependent manner, we performed Affymetrix GeneChip analysis with HG-U133 plus 2.0 arrays containing 54,675 probe sets. The identified genes were analyzed using the Ingenuity Pathway Analysis Tool to investigate the functional network and gene ontology. Changes in mRNA expression in the genes were assessed by real-time reverse transcriptase-polymerase chain reaction. RESULTS: We identified 98 genes with expression levels that were altered significantly at least twofold in each of the three carbon-irradiated OSCC cell lines at all dose points compared with nonirradiated control cells. Among these, SPHK1, the expression of which was significantly upregulated by carbon ion irradiation, was modulated little by X-rays. The function of SPHK1 related to cellular growth and proliferation had the highest p value (p = 9.25e-7 to 2.19e-2). Real-time reverse transcriptase-polymerase chain reaction analysis showed significantly elevated SPHK1 expression levels after carbon ion irradiation (p < 0.05), consistent with microarray data. Clonogenic survival assay indicated that carbon ion irradiation could induce cell death in Ca9-22 cells more effectively than X-rays. CONCLUSIONS: Our findings suggest that SPHK1 helps to elucidate the molecular mechanisms and processes underlying the biologic response to carbon ion beams in OSCC.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Long-term results of free radial forearm flap used for oral reconstruction: functional and histological evaluation.

PURPOSE: The aim of this study was to evaluate the radial forearm flap with regard to recovery of sensory function, general performance status, cutaneous blood flow and histological observations. PATIENTS AND METHODS: Thirty patients (23 male and 7 female) with oral carcinoma underwent immediate reconstruction with radial forearm flap after ablative surgery and returned for evaluation. Interviews were conducted to assess the degree of articulation and mastication. RESULTS: Sensory function tests suggested the restoration of cutaneous sensibility of the forearm flap. Histological findings indicated mucosa-like changes of flaps about 10 months after reconstruction. The clarity of conversation recovered favorably in most patients. However, the degree of recovery was generally related to the time after surgery. CONCLUSION: The radial forearm flap is a unique flap with specific characters that allowed for best available functional reconstruction of the oral cavity in terms of restoration of sensation, performance, and histological changes to adapt to the new oral environment.

Adult↗

PubMed2006

Aberrant expression of histone deacetylase 6 in oral squamous cell carcinoma.

The structure and function of chromatin can be altered by modifications to histone. Histone acetylation is a reversible process governed by histone acetyltransferases and histone deacetylases (HDACs). HDAC6 is a subtype of the HDAC family that deacetylates alpha-tubulin and increases cell motility. We investigated the expression levels of HDAC6 mRNA and protein expression in oral squamous cell carcinoma (OSCC)-derived cell lines and human primary OSCCs to elucidate the potential involvement of HDAC6 in OSCC. Using quantitative real-time reverse transcription polymerase chain reaction and Western blots on nine OSCC-derived cell lines and normal oral keratinocytes (NOKs), HDAC6 mRNA and protein expression were commonly up-regulated in all cell lines compared with the NOKs. Immunofluorescence analysis detected HDAC6 protein in the cytoplasm of OSCC cell lines. Similar to OSCC cell lines, high frequencies of HDAC6 up-regulation were evident in both mRNA (74%) and protein (51%) levels of primary tumors. Among the clinical variables analyzed, the clinical tumor stage was found to be associated with the HDAC6 expression states. The analysis indicated a significant difference in the HDAC6 expression level between the early stage (stage I and II) and advanced-stage (stage III and IV) tumors (P=0.014). These results suggest that HDAC6 expression may be correlated with tumor aggressiveness and offer clues to the planning of new treatments.

Aged↗

PubMed2005

Evaluation of taste sensation following tongue reconstruction by microvascular forearm free flap.

PURPOSE: The objective of this study was to examine the restoration process of taste perception in patients after reconstruction of the tongue using microvascular forearm flaps. PATIENTS AND METHODS: Twelve patients, aged 28 to 70 years with a mean of 59.6 years consisting of 9 men and 3 women, were enrolled in this study. Examination results based on the filter paper disk and whole mouth methods were evaluated on a 6-point rating scale. RESULTS: In none of the patients was it possible to detect any perception of the test tastes in the regions under the control of the chorda tympani and glossopharyngeal nerves on the reconstructed side, indicating a "nondetectable" grade 6 result. The evaluation results for the normal tongue region under the control of the chorda tympani in the patients after tongue reconstruction showed a mean grade of 4.7 for the sweet, 4.9 for the salty, 4.6 for the sour, and 4.4 for the bitter taste. Mean grade determined by the whole mouth method was 3.6 for sweet, 3.3 for salty, 3.0 for sour, and 3.6 for bitter. CONCLUSION: No taste perception was detected in the regions of the tongue reconstructed with forearm flaps. These results led us to assume that compensatory taste perception must occur in other regions of the oral cavity because none of our postsurgery patients showed any serious taste disorder.

Adult↗

PubMed2005

Patterns of mandibular invasion by gingival squamous cell carcinoma.

PURPOSE: This study examined patterns of invasion of lower gingiva cancer into the mandible. Our goal was to clarify the most common routes for gingival squamous cell carcinoma to enter and spread within the mandible. PATIENTS AND METHODS: The subjects were 176 patients with lower gingival squamous cell carcinoma who underwent mandibulectomy; all tumors were examined histopathologically. The method of mandibulectomy was decided on the basis of conventional plain radiographic and computed tomographic findings. RESULTS: The tumor extended to the periosteum in 33%, to the cortical bone in 23%, and to the bone marrow in 9% of the patients who underwent mandibular resection. The remaining 35% of our patients had no evidence of mandibular invasion. CONCLUSION: The area of bone resorption on preoperative clinical and radiographic examinations often disagreed with the extent of mandibular invasion on histopathologic examination.

Adult↗

PubMed2005

Loss of heterozygosity and microsatellite instability on chromosome 2q in human oral squamous cell carcinoma.

Allelic imbalance or loss of heterozygosity (LOH) and microsatellite instability (MSI) have been used to identify regions on chromosomes that may contain putative tumor suppressor genes. To obtain a detailed understanding of genetic alterations in oral cancer, 10 highly polymorphic markers mapped on chromosome 2 were used to examine 25 cases of oral squamous cell carcinoma (SCC). With these, we analyzed chromosome 2q for LOH in 25 primary oral SCCs and constructed a deletion map for this arm of the chromosome. LOH was detected in 16 (64%) of the 25 informative samples at one or more of the loci examined. MSI was observed in 5 (20%) of the 25 cases. Among the loci examined, LOHs were restricted to D2S1328 and D2S206 on chromosomes 2q14-21 and 2q36, respectively, with the former locus showing a rate of 5 (20.8%) and the latter a rate of 6 (25%) of the 24 informative cases. These observations taken in conjunction with data from 40 former cases analyzed at our laboratory suggest that the high incidence of LOH at chromosome 2q is associated with carcinogenesis of oral SCC. The regions that comprise the D2S1328 and D2S206 loci may play an important role in the development of oral SCC, perhaps containing sites that harbor a putative tumor suppressor gene.

Adult↗

PubMed2005

Model surgery technique for Le Fort I osteotomy--alteration in occlusal plane associated with upward transposition of posterior maxilla.

It is difficult to translate analytical values into accurate model surgery by traditional methods, especially when moving the posterior maxilla. This is because cephalometric radiographic analysis generated information on movement of the posterior nasal spine (PNS) can not be recreated in model surgery. Therefore, we propose a method that accurately reflects such analysis and simulation of movement using Quick Ceph 2000 (Orthodontic Processing Corporation, USA). This will allow the enrichment of model surgery prior to actual surgery in cases where upward movement of the posterior maxilla is involved. All patients who participated in this study had skeletal mandibular prognathism characterized by a small occlusal plane angle in respect to the S-N plane. Cephalometric radiographs were taken and analyzed with the Quick Ceph 2000. Pre- and post-surgical evaluations were performed using Sassouni arc analysis and Ricketts analysis. Prior to transposition, we then prepared an anterior occlusal bite record on a model mounted on an articulator. This bite was then used as a reference when the molar parts were to be transposed upwards. The use of a occlusal bite permitted an accurate translation of the preoperative computer simulation into model surgery, thus facilitating favorable surgical results.

Cephalometry↗

PubMed2004

Material analysis of AO plate fracture cases.

PURPOSE: The clinical observation of fracture cases and material evaluation of fractured titanium plates were performed to investigate the causes of fracture. PATIENTS AND METHODS: Fracture of titanium plates occurred in 4 patients of the 110 mandibular reconstructions. We clinically and experimentally evaluated plate fracture cases among cases in which primary reconstruction using titanium plates was performed after the mandibular resection. RESULTS: Titanium plate fracture was frequently observed in L-type defect cases in which angle-type plates were used, and fracture mainly occurred in the anterior region of the mandibular angle. Material analysis suggested that the occurrence of fracture can be prevented by eliminating constricted parts on the internal side of the plates. CONCLUSIONS: The causes of fracture were thought to be the use of plates under the conditions of comparatively frequent repeated application of stress or fatigue fracture caused by stress concentration, depending on the form of the plate.

Adolescent↗

PubMed2004

Acinic cell carcinoma found by recurrence of a mucous cyst in the sublingual gland.

This case report describes an acinic cell carcinoma found by a recurrence of a ranula in the sublingual gland. A 42-year-old male was admitted to the hospital of the Tokyo Dental College with a swelling in his right oral floor but without pain. The lesion was treated by windowing the same day under the diagnosis of a ranula, but the swelling appeared again at the same area eight months after the first operation. A resection was performed, and the specimen was sent to the clinical laboratory for pathological diagnosis. Proliferating serous cells were seen in part of the wall of an exudative mucous cyst. PAS staining was partially positive, and immunohistochemical staining for S-100 protein, lactoferrin, and amylase were also positive in cytoplasmic granules. This report concludes that the pathological diagnosis is beneficial in clarifying the reasons for the recurrence of a benign lesion.

Adult↗

PubMed2003

Allelic loss of chromosome 2 in human oral squamous cell carcinoma: correlation with lymph node metastasis.

To evaluate the role of chromosome 2 deletions in human oral squamous cell carcinoma (SCC) progression and to define the precise location of putative tumor suppressor genes, we examined 40 primary tumors and seven lymph node metastatic tumors from 40 patients with oral SCC by the polymerase chain reaction (PCR)-loss of heterozygosity (LOH) assay, using 10 different polymorphic loci on the long arm of chromosome 2. LOH was observed in 67.5% of the patients at one or more loci on the chromosome 2q. Two commonly deleted regions with high frequency of LOH, D2S1327 region at 2q32-35 (31.6%) and D2S206 region at 2q36 (36.7%), were identified by the deletion mapping of chromosome 2q, suggesting the presence of putative tumor suppressor genes associated with oral SCC. Examination of seven metastatic tumors also revealed four commonly deleted regions, D2S436, D2S1327, D2S155, and D2S164. Of these four regions D2S1327 region has no significant increase in the frequency of LOH between in primary tumors and in metastatic tumors. However, at other three regions the frequencies were much increased in metastatic tumors, comparing the results in primary tumors. Especially, very high frequencies of LOH in metastatic tumors were detected at two regions on 2q35, 100.0% at D2S155 and 57.1% at D2S164, suggesting the significant relationship between lymph node metastasis and LOH at these two regions. Our results indicate that LOH on chromosome 2q is a common event in oncogenesis and/or progression of oral SCC, and also suggest that the LOH at 2q35 play a significant role in the lymph node metastasis.

Carcinoma, Squamous Cell↗

PubMed2003

Allelic loss on chromosomes 2q, 3p and 21q: possibly a poor prognostic factor in oral squamous cell carcinoma.

Loss of heterozygosity (LOH) correlates with inactivate tumor suppressor gene. The aim of this study was to see if LOH on chromosomes 2q, 3p and 21q correlated with a poor prognostic factor in oral squamous cell carcinoma (SCC). We analyzed chromosomes 2q, 3p and 21q for LOH in 40 primary oral SCCs using 30 markers and constructed a deletion map for these chromosome arms. Significant LOH (>20%) occurred at alleles in chromosome bands 2q14-21 (21.7%), 2q32-35 (31.6%), 2q35 (21.1%), 2q36 (36.7%), 3p25 (32.4%), 3p21.3 (23.8%), 21q11.1 (52.4%), 21q21 (21.6%) and 21q22.1 (22.2%). A significant correlation was observed between the number of regions showing LOH at 2q and TNM clinical stage (P=0.0063), consistent with the progressive accumulation of genetic errors during the development oral SCC. The number at more than two LOH loci was significant with a poor prognosis at 2q (P=0.0208). These findings demonstrate that oral SCC exhibits genetic alterations at multiple loci and that allelic loss at more than two locations is indicative of a poor prognosis. This is the first study to demonstrate the prognostic significance of LOH at 2q, 3p and 21q for oral cancer and may help to identify patient who should receive more aggressive treatment.

Adult↗

PubMed2003

Histopathologic damage to vessels in head and neck microsurgery.

PURPOSE: This study assessed the incidence of pre-existing damage in recipient arteries excised before the vessels were used for microvascular anastomoses between 1988 and 1999. PATIENTS AND METHODS: Recipient arteries of the head and neck region from 100 patients who had undergone ablative surgery requiring microvascular tissue reconstruction were examined histologically. Past illnesses believed to be risk factors included hypertension, myocardial disease, and diabetes. Blood vessels chosen for microsurgical anastomoses were examined using histological staining, scanning electron microscopy, and immunofluorescence. RESULTS: Of the patients undergoing microvascular surgery, 51% showed histologic vessel abnormalities. Marked thickening of the blood vessel wall and severe exfoliation of the endothelial cells were observed in most arteries. Thickening of the intima was evaluated using scanning electron microscopy (Friedman's method; Microvasc Res 3:416, 1971). Values higher than twice the ratio of wall thickness-to-lumen diameter were observed in 9 recipient arteries. Six graft failures were correlated with both technical errors and pre-existing vessel lesions. CONCLUSIONS: This study revealed that most patients undergoing microsurgery in the head and neck region had pre-existing damage to vessels that hindered anastomoses. Pre-existing changes in the recipient arteries may cause technical difficulties and must be regarded as additional factors contributing to graft failure.

Adult↗

PubMed2003

Reconstruction of the inferior alveolar nerve by autologous graft: a retrospective study of 20 cases examining donor nerve length.

The purpose of this study was to confirm the length and kind of donor nerves used in nerve grafts for reconstruction of inferior alveolar nerve defects. The authors conducted a retrospective study of surgeries that were performed between 1977 and 1996. A total of 20 patients underwent nerve grafting procedures during this period. The greater auricular nerve was selected as the donor nerve in 16 cases, while the sural nerve was selected in 4. Mean lengths of donor nerves were 7.28 +/- 1.6 cm and 11.5 +/- 3.4 cm for the greater auricular and sural nerves, respectively. As indicated, the sural nerves were significantly longer (p < 0.01). Mean lengths of donor nerves grafted for partial resection and hemi-mandibulectomy were 7.23 +/- 1.6 cm and 10.8 +/- 3.4 cm, respectively. Statistical analysis indicated that grafts used in the hemi-mandibulectomy group were significantly longer (p < 0.05). In terms of types of donor nerve used in mandibulectomies, the greater auricular nerve was used in the majority of partial resections, and the sural nerve was employed for hemi-mandibulectomy.

Adolescent↗

PubMed2003

Over-expression of DNA methyltransferases and CDKN2A gene methylation status in squamous cell carcinoma of the oral cavity.

The present study was designed to investigate the potential relationship between CDKN2A (p16) gene hypermethylation, which has reported to be frequently observed in oral squamous cell carcinomas (OSCCs), and expression of human DNA methyltransferases (DNMTs: DNMT1, DNMT3A and DNMT3B). Twenty-five pairs of primary OSCCs and matched normal oral mucosa tissues were examined. The p16 gene was hypermethylated (48%) in the tumors showing significant down-regulation of both mRNA and protein expressions. A demethylation assay on 8 OSCC-derived cell lines was also performed by means of treatment with the demethylating agent, 5-aza-2'-deoxycytidine. Four of 5 cell lines showing down-regulation of the p16 gene, revealed re-activation of gene expression after the treatment. In contrast, frequent over-expression of DNMT mRNA expression, also found in the expression of the proteins, was detected: DNMT1 at 72% and DNMT3A at 56%, and DNMT3B at 64%, respectively. However, we could not identify any statistical significance between p16-hypermethylation status in individual tumors and the expression of any of the three DNMTs. These data suggest that hypermethylation of the p16 gene and up-regulation of DNMTs are involved in oral carcinogenesis, but they may be through different mechanisms.

Carcinoma, Squamous Cell↗

PubMed2002

The presence of candidate tumor suppressor gene loci at chromosome 3p for oral squamous cell carcinomas.

We investigated the short arm of chromosome 3 (3p) for allelic imbalances, including loss of heterozygosity (LOH) and microsatellite instability (MSI) in 40 primary oral squamous cell carcinomas (SCCs) using 10 microsatellite markers and constructed a deletion map for this chromosome arm. We examined 40 primary tumor tissues, 40 corresponding normal tissues, and seven lymph node metastatic tissues. LOH at one or more loci was found in 24/40 (60%) of tumors. Deletion mapping of these tumors revealed at least three discrete, commonly deleted regions on the chromosome arm. Furthermore, we detected MSI in six of those tested cases (15%). We compared our results with the clinicopathologic features. A number of sites displaying LOH at 3p could be detected in early stage lesions, and the frequencies of LOH tended to be higher in later clinical stages. Thus, the frequent LOH was observed from early stage in pTNM classification. An unknown tumor suppressor gene in the genesis of oral squamous cell carcinoma may exist in 3p.

Adult↗

PubMed2002

Muscle-fiber characteristics in adult mouse-tongue muscles.

To clarify functions of the mouse-tongue muscles, proteins such as myocin heavy chain (MHC) 2a and MHC-2b, which are isoforms of the fast-twitch fiber type myosin heavy chain, in the lateral margin of the tongue were observed by reverse transcription polymerase chain reaction and immunohistochemical analyses. The main MHC isoform in the superior longitudinal muscle of the tongue was MHC-2b, with the fastest function and the main MHC isoform in the transverse muscle of the tongue was MHC-2a. These findings suggested that the fastest function is necessary for the superior longitudinal muscle of the tongue, which is useful for moving the tongue in and out of the mouth in the sagittal direction, showing different cellular biological properties of the myofibers from those of the transverse muscle of the tongue.

Animals↗

PubMed2002

Fracture of mandibular reconstruction plates used after tumor resection.

PURPOSE: We assessed the incidence of fractured plates after primary temporary AO plate reconstruction of the mandible following tumor resection. PATIENTS AND METHODS: One hundred ten patients were retrospectively evaluated according to the extent of the tumor, anatomic location of the reconstruction, type of plate, additional use of radiotherapy or flap surgery (or both), and the incidence of fractured plates. RESULTS: Fractured plates occurred in 8 of 110 patients. Most occurred less than 6 months after surgery. All of the 8 patients had a malignant tumor; 2 had received radiation therapy and 4 had skin flaps placed. The fractured plate was the straight type in 1 patient and the angular type in 7 patients. Among patients who had fractured plates, the average number of remaining teeth was 12.8 in the maxilla and 9.5 in the mandible. CONCLUSIONS: Fractured plates were more common among patients with oral cancer with a segmental defect that did not cross the midline in whom an angular-type plate was used and no bone grafting was performed.

Adolescent↗