| Project/Area Number |
59440076
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Niigata University |
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Principal Investigator |
OZAWA Hidehiro Niigata University School of Dentistry, Professor, 歯学部, 教授 (60018413)
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| Co-Investigator(Kenkyū-buntansha) |
EJIRI Sadakazu Niigata University School of Dentistry,Research Associate, 歯学部, 助手 (40160361)
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| Project Period (FY) |
1984 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥23,000,000 (Direct Cost: ¥23,000,000)
Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1985: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1984: ¥21,000,000 (Direct Cost: ¥21,000,000)
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| Keywords | Freeze-substitution / matrix vesicles / calcification / elemental analysis / ALPase; lead acetate / ectopic calcification / 異所性石灰化 / 膠原線維 / 基質小胞性石灰化 / コラーゲン性石灰化 / 急速凍結置換法 / 鉛トレーサー実験 / アルカリホスファターゼ活性 |
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| Research Abstract |
The basic objective is to elucidate the biological calcification mechanism by means of electron microscopy(EM) and cytochemistry. The major approach was designed to reveal the ultrastructural and elemental analytical characteristics of the initial stage of the hard tissue calcification. Freeze-substitution methods at the liquid helium temperature were employed to obtain high resolution electron micrograaphs of developing crystals, and to detect elements by the quantitative EDX. At the beginning of matrix vesicle(MV) calcification, crystals within the MVs of either rat calvaria or the tibial growth plate showed the lattice images (LIs) poorly resolved as about 0.25nm period, and gave a mean Ca/P molar ratio(MR) of 1.3, indicating octacalcium phosphate(OCP). Crystals extended from MVs showed the distinct LIs resolved as the same period, and gave a mean Ca/P MR of 1.5, indicating tricalcium phosphate(TCP). At the more advanced stage of calcification, crystals gave a mean Ca/P MR of 1.67,
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indicating apatite(HA). This suggests that calcification at the early stage may occur from ACP or OCP within the MVs, and transform into HA through TCP. The cytochemical location of ALPase activity of fetal rat parietal bones was observed to elucidate the relationship between cyto-differentiation of osteoblasts and the calcification process. Differentiating osteoblasts showed intense ALPase activity on the plasma membranes as well as MVs. The closer to the initially calcified area, the stronger was the ALPase activity in both MVs and osteoblasts, though the activity was not shown in the plasma membrane surfacing on the bone matrix where the calcification was more extensive. The chicken tendon calcification was also examined. Fibrocartilage cells in the leg tendon produced MVs in which the initial calcification occured, and in turn crystals extended on the collagen fibrils adjacent to the calcified MVs. The similar result was obtained by using lead as a tracer for calcium deposition. The ectopic calcification induced by the administration of lead acetate to the rat subcutaneous connective tissue was also studied by EM, resulting that the initial lead deposition occured within the degenerated collagen fibrils, and in turn apatite crystal formation began at the same sites of lead deposition. Less
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