Junya Yano

Effects of sequential exposure to lipopolysaccharide and heat stress on dental pulp cells

In the present study, we examined the effects of sequential exposure to bacterial lipopolysaccharide (LPS) and heat stress on dental pulp cells. LPS induced the proliferation of pulp cells through the activation of p38 MAPK. HSP27 was expressed in cells with or without LPS during the entire period of heat stress, while transiently phosphorylated by short‐term heat stress. In LPS‐treated cells, short‐term heat stress also induced the phosphorylation of HSF1. The immediate phosphorylation of HSF1 and HSP27 in LPS‐treated cells by short‐term heat stress occurred dependent on the activation of p38 MAPK. However, with long‐term heat stress, the activation of HSF1 and induction of HSP27 occurred independent of p38 MAPK. Further, full activation of Akt in LPS‐treated cells was immediately induced by short‐term heat stress and lasted during the entire period of heat stress. IκBα was induced and phosphorylated throughout sequential exposure to LPS and heat stress. These results suggest that LPS has the unique effects on the cytoprotection and the cell death of pulp cells during heat stress through the modification and the activation of heat stress responsive molecules, HSF1 and HSP27, and cell survival molecules, Akt and NF‐κB/IκBα. J. Cell. Biochem. 99: 797–806, 2006.

Apoptosis and survivability of human dental pulp cells under exposure to Bis-GMA

Objective In the present study, we examined whether 2, 2-bis [4-(2-hydroxy-3methacryloxypropoxy) phenyl] propane (Bis-GMA) has effects on LSC2 cells, human dental pulp cell line. Material and Methods The viability, cell cycle, and morphology of LSC2 cells were analyzed after exposure to several different concentrations of Bis-GMA. The recovery of viability of Bis-GMA exposed cells was also analyzed in the condition without Bis-GMA. Further, penetration of Bis-GMA to dentin disc was examined using isocratic high-performance liquid chromatography. Results There was a concentration-dependent decrease in cell proliferation and an increase in cell number in the sub-G1 population after exposure to Bis-GMA. Furthermore, the cells showed typical characteristics of apoptotic cells after the exposure to high concentration of Bis-GMA. In contrast, cells exposed to lower concentrations of Bis-GMA recovered their viability after being cultured without Bis-GMA. We also found that Bis-GMA is capable of penetrating 1-mm-thick dentin discs, though the penetrated concentration was lower than that showing cytotoxicity. Conclusion These results suggest that Bis-GMA has cytotoxic effects, though dental pulp exposed to lower concentrations is able to recover their viability when Bis-GMA is removed.

Comparison between Two Methods for Fluorapatite Determination

tt Synthetic hydroxyapatite (HAP) was stirred in the soulution having various concentrations of fluoride ion. The fluoride products were qualified by X-ray diffraction (XRD), and fluorapatite (FAP) was quantitatively determined by two methods: Onikis ESR technique and Caslavskas CaF2 extraction method. The FAP production could be accurately quantified by ESR technique when the concentration of fluoride ion in the solution was below leOppm. This technique, however, was not valid at the higher concentration of fluoride ion exceeding 200ppm since the FAP signal became obscure with an interference by the increased CaF2 precipitates. These findings in ESR were well suported by the XRD analysis. The CaF2 extraction method by KOH, on the other hand, showed considerably different results from those in ESR. It seerned that all the precipitated CaF2 could not be completely rernoved by 1 M KOH employed in this study.

A Survey of First-appointed Patients Clinical Treatments at the Clinic of Operative Dentistry and Endodontics in Kyushu Dental College Hospital : From 1997 to 1999

treatment. , The total number ef first-appointed patients during the three years was 1534 which consists of 581 males (38.0%) and 952 females (62.0-%). By age, the largest group was patients in the forties (18.0 %), and groups of patients at ages frorn 20 to 69 were 83.7 % of the total number. Patients from Kokurakita-ward showed 24.6 % of this total, and patients frorn the whole wards of Kitakyushu-city showed 76.4 % in all, The ratios of introduction from outside of this h6spital and other clinics of this hospital were 19.5% and 28.0%,