| Co-Investigator(Kenkyū-buntansha) |
HAMAZAKI Tatsuo Research Institute, International Medical Center of Japan, Dept.of Regenerative Medicine, Division Chief, 細胞組織再生医学研究部, 室長 (70228534)
KITA Kazuko Chiba Univ., Graduate School of Medicine, Lecturer, 大学院医学研究院, 講師 (80302545)
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| Budget Amount *help |
¥15,600,000 (Direct Cost: ¥15,600,000)
Fiscal Year 2006: ¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 2005: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Research Abstract |
The purpose of this research was to develop the simple method to determine the substances leached from polymerized dental resins immersed in human saliva, to establish the inductive method of ciliated epithelial cells in trachea using murine embryonic stem (ES) cells in vitro and to develop the system for the cytotoxic evaluation of dental materials using this system, and to examine the effect of resin monomers and resin additives on the expression levels of stress proteins, such as HSP27, HSP70, GRP78, GRP94 and HSP90α.
Dental monomers were degraded in saliva and fetal bovine serum, and then its decomposition rate was different, depending on the kind of monomer. In addition, the decomposition rate of benzoyl peroxide was different, depending on the solvents used to dissolve benzoyl peroxide. On the other hand, when di-n-butyl phthalate (DBP) was added in human saliva containing polysorbate 80 (TW80) used as a pharmaceutical additive, DBP was changed into monobutyl phthalate (MBP) time-
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dependently as well as the case of human saliva and its changes were inhibited by TW80 concentration-dependently. The half time of DBP was longer in order of 0.1(3/0>0.08%>0.05%>0.025%=0.01% TW80, but the remarkable inhibition was not observed at 0.1% TW80 later for 24 hours either. From these results, the concentration of TW80 added to the saliva was set at 0.025% and phthalates leached from cured RTSMs were examined. The quantity of leached DBP increased with time. It may be useful to use TW80 as an elution stimulant.
The inductive for the trachea-like ciliated epithelial cells method was developed successfully and the inducted cilia were beating at a frequency of 17-20 Hz. The epithelial cells expressed TTF-1 and SPC which were specific proteins of trachea epithelium. Judging from cytotoxic test using this culture system, TD_<50> was almost the same value that was reported previously. Furthermore, the expression of Foxj-1 was apparently decreased in low dose than other reports which measured the level of glutathione and oxidized glutathione of gingival fibroblasts.
From the results of the effect of resin monomers and resin additives on the expression levels of stress proteins such as HSP27, HSP70, GRP78, GRP94 and HSP90α, the expression levels of stress proteins were increased after β-estradiol treatment at a concentration over 0.01μM in the hERα-expressed cells. 1μm BPA has an effect similar to that of β-estradiol on the expression of the stress proteins. In addition, among the 4 dental additives such as hydroquinone, 4-methoxyphenol, p-tert-butylphenol and p-cumyl phenol, 4-methoxyphenol induced an increase in the levels of these stress proteins at concentrations ranging from 1 to 10μM in the hERα-expressed cells. 4-Methoxyphenol in addition to BPA has an estrogen-like action on the induction of stress proteins. Thus, the hERα-expressed cells may be useful for evaluating the stress protein-inducing effect of dental resins via estrogen action.
From these results, each evaluation method developed by this present research may be the high new sensitive biological evaluation method which can be applied to the cytotoxicity test of the components of the dental resin used in dentistry. Less
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