Our long-term strategy for understanding normal and pathological enamel mineralization is to determine: a) the driving force for precipitation of calcium phosphate salts during amelogenesis, b) the cellular role in establishing such a driving force, and c) the possible regulatory mechanism(s) of amelogenesis related to the matrix-mineral interaction. The information obtained will be applied to the study of pathological amelogenesis using animal models (minipigs and rats) under various fluoride regimes. The present proposal includes the following specific aspects: 1) Separation of the fluid phase from the secretory enamel of a single animal (minipig), determination of its ionic composition, and changes in it induced by pathological agents (fluoride). Analyses of micro volumes of the fluid will be conducted by the use of ion chromatography and micro- electrodes. 2) Identification of the calcium-binding ligands in the fluid. The protein constituents in the fluid will be separated by microdialysis, electrophoresis, and chromatography. The calcium-binding properties of the separated fluid constituents will be determined through the use of ion- specific electrodes, 45Ca autoradiography, and flow-rate dialysis. Based on the foregoing results, we will re-evaluate the degree of saturation of enamel fluid with respect to enamel and other calcium phosphates of interest. 3) Investigation of the properties of amelogenins and enamelins of porcine and murine models, and their degradation in situ. The properties concerned are: a) their selective adsorption onto apatitic surfaces, b) their solubility in physiologic aqueous solutions, and c) their hydrophobic/hydrophilic nature. 4) The mechanism of adsorption of the secreted amelogenin onto apatitic surfaces. The selective adsorption of the amelogenin will be related to the presence of specific segments at the N- and C-terminals, both of which have a high homology in the matrix proteins of mammal enamel. Efforts will also be made to ascertain the effect of segments on the molecular conformation in solutions and on solid surfaces. 5) Investigation of the functional aspects of the matrix-mineral interaction in enamel mineralization. Interest will be focused on the effects of protein coatings of apatite crystals on (a) the incorporation of ions (calcium, phosphate, and fluoride) from solutions onto the crystal surfaces, (b) kinetics of precipitation in fluid-like environments, and (c) the aggregation and morphology of growing crystals.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE007623-08
Application #
3221284
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Project Start
1986-03-01
Project End
1994-03-31
Budget Start
1993-03-01
Budget End
1994-03-31
Support Year
8
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Forsyth Institute
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02142
Aoba, T (1996) Recent observations on enamel crystal formation during mammalian amelogenesis. Anat Rec 245:208-18
Aoba, T; Taya, Y; Sato, A et al. (1995) Mechanistic understanding of enamel mineralization under fluoride regime. Connect Tissue Res 33:145-9
Aoba, T (1994) Strategies for improving the assessment of dental fluorosis: focus on chemical and biochemical aspects. Adv Dent Res 8:66-74
Goto, Y; Kogure, E; Takagi, T et al. (1993) Molecular conformation of porcine amelogenin in solution: three folding units at the N-terminal, central, and C-terminal regions. J Biochem 113:55-60
Miake, Y; Shimoda, S; Fukae, M et al. (1993) Epitaxial overgrowth of apatite crystals on the thin-ribbon precursor at early stages of porcine enamel mineralization. Calcif Tissue Int 53:249-56
Aoba, T; Shimoda, S; Akita, H et al. (1992) Anti-peptide antibodies reactive with epitopic domains of porcine amelogenins at the C-terminus. Arch Oral Biol 37:249-55
Akita, H; Fukae, M; Shimoda, S et al. (1992) Localization of glycosylated matrix proteins in secretory porcine enamel and their possible functional roles in enamel mineralization. Arch Oral Biol 37:953-62
Aoba, T; Moreno, E C; Shimoda, S (1992) Competitive adsorption of magnesium and calcium ions onto synthetic and biological apatites. Calcif Tissue Int 51:143-50
Aoba, T; Shimoda, S; Shimokawa, H et al. (1992) Common epitopes of mammalian amelogenins at the C-terminus and possible functional roles of the corresponding domain in enamel mineralization. Calcif Tissue Int 51:85-91
McKee, M D; Aoba, T; Moreno, E C (1991) Morphology of the enamel organ in the miniature swine. Anat Rec 230:97-113

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