Hitoshi Toyoma

Nickel Ion Inhibits Nuclear Factor-Kappa B Activity in Human Oral Squamous Cell Carcinoma

Background The spontaneous IL-8 secretion observed in OSCC is partially dependent on the disregulated activity of transcription factor NF-κB. Nickel compounds are well established human carcinogens, however, little is known about the influence of nickel on the spontaneous secretion of IL-8 in oral squamous cell carcinoma (OSCC) cells. The aim of the present study was to investigate whether Ni2+ ions can influence on IL-8 secretion by OSCC. Methods and Results The IL-8 secretion was measured by ELISA. The expression of IL-8 mRNA was examined by real-time PCR. The NF-κB activity was measured by luciferase assay. The phosphorylation status and nuclear localization of NF-κB subunits were examined by Western blotting or Transfactor kit and immunofluorescence staining, respectively. The interaction of NF-κB p50 subunit and Ni2+ ions was examined by Ni2+-column pull down assay. The site-directed mutagenesis was used to generate a series of p50 mutants. Scratch motility assay was used to monitor the cell mobility. Our results demonstrated that, on the contrary to our expectations, Ni2+ ions inhibited the spontaneous secretion of IL-8. As IL-8 reduction was observed in a transcriptional level, we performed the luciferase assay and the data indicated that Ni2+ ions reduced the NF-κB activity. Measurement of p50 subunit in the nucleus and the immunofluorescence staining revealed that the inhibitory effect of Ni2+ ions was attributed to the prevention of p50 subunit accumulation to the nucleus. By Ni2+-column pull down assay, Ni2+ ions were shown to interact directly with His cluster in the N-terminus of p50 subunit. The inhibitory effect of Ni2+ ions was reverted in the transfectant expressing the His cluster-deleted p50 mutant. Moreover, Ni2+ ions inhibited the OSCC mobility in a dose dependent fashion. Conclusions Taken together, inhibition of NF-κB activity by Ni2+ ion might be a novel therapeutic strategy for the treatment of oral cancer.

Effectiveness of surgical template for dental implants placed in bone graft

PATIENT Marginal mandibulectomy was performed on a 30-year-old woman with an ameloblastoma in the left side of the mandible. Subsequently, the patients chief complaints were in regard to the restoration of masticatory function and esthetics. Realizing that a free iliac crest graft and implant were necessary, we made a diagnostic wax-up and surgical template to match the maxillary and mandibular alveolar bone position. The surgical template was used to determine the position of a free iliac crest in the operating room. When the final restoration was finished, good occlusal balance had been achieved. DISCUSSION In this case, an oral surgeon as well as a prosthodontist confirmed the graft bone position by using the surgical template in the operating room. Therefore, it was possible to place the graft bone into the preplanned position and carry out the treatment plan smoothly from the first implant operation to the final restoration. CONCLUSION This clinical report describes the importance of free iliac crest graft positions, the surgical template and collaboration between a prosthodontist and oral surgeon in forming the proper treatment plan.

A study on high-strength denture teeth. Part I. Wear resistance of anterior artificial teeth.

High-strength denture teeth (hereafter referred to as HS teeth) were developed to improve hardness and wear resistance of the conventional plastic denture teeth, while retaining their feature of easy occlusal adjustment.The objective of this study was to evaluate wear resistance of HS teeth. We conducted the wear test and measured surface roughness, using six types of anterior artificial teeth; ie.three types of HS teeth and three types of conventional plastic denture teeth (hereafter referred to as PL teeth) which served as the control.The result of the toothbrush abrasion test revealed that the HS teeth have about 5 times grater wear resistance than the conventional PL teeth. It was also found out that the type of artificial teeth and the number of wear-testing strokes made a significant influence on the surface roughness of artificial teeth.(P<0.05)