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Titolo:
Localizational alterations of calcium, phosphorus, and calcification-relate organics such as proteoglycans and alkaline phosphatase during bone calcification
Autore:
Hoshi, K; Ejiri, S; Ozawa, H;
Indirizzi:
Niigata Univ, Fac Dent, Dept Oral Anat 1, Niigata 9518514, Japan Niigata Univ Niigata Japan 9518514 t Oral Anat 1, Niigata 9518514, Japan
Titolo Testata:
JOURNAL OF BONE AND MINERAL RESEARCH
fascicolo: 2, volume: 16, anno: 2001,
pagine: 289 - 298
SICI:
0884-0431(200102)16:2<289:LAOCPA>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
EPIPHYSEAL GROWTH PLATE; ENERGY-LOSS SPECTROSCOPY; MATRIX VESICLES; ENDOCHONDRAL OSSIFICATION; CHONDROCYTE CULTURES; FREEZE-SUBSTITUTION; CARTILAGE MATRIX; CUPROLINIC BLUE; LINK PROTEIN; BOVINE BONE;
Keywords:
calcification; bone; proteoglycan; alkaline phosphatase; energy-filtering transmission electron microscopy;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
81
Recensione:
Indirizzi per estratti:
Indirizzo: Hoshi, K Niigata Univ, Fac Dent, Dept Oral Anat 1, 2-5274 Gakkocho Dori, Niigata 9518514, Japan Niigata Univ 2-5274 Gakkocho Dori Niigata Japan 9518514 4, Japan
Citazione:
K. Hoshi et al., "Localizational alterations of calcium, phosphorus, and calcification-relate organics such as proteoglycans and alkaline phosphatase during bone calcification", J BONE MIN, 16(2), 2001, pp. 289-298

Abstract

To further approach the mechanisms of bone calcification, embryonic rat calvariae were observed at electron microscopic level by the means of fine structures and various cytochemical localizations, including nonspecific proteoglycan (PG) stained by cuprolinic blue (CB), decorin, chondroitin sulfate, hyaluronan, and alkaline phosphatase (ALP), as well as the elemental mapping of calcium (Ca) and phosphorus (P) by energy-filtering transmission electron microscopy (EFTEM). In the calvariae, calcification advanced as the distance from osteoblasts increased. Closer to the osteoblasts, the osteoid was marked by an abundance of CB-positive PGs around collagen fibrils. After crystallization within matrix vesicles, calcified nodules formed and expanded, creating a coherent calcified matrix. The sizes of CB-positive PG-like structures diminished as calcification proceeded. Although small CB-positive structures were accumulated in early stage-calcified nodules, they werelocalized along the periphery of larger calcified nodules. Cytochemical tests for decorin, chondroitin sulfate, and hyaluronan determined their presence in the areas around collagen fibrils of the osteoid, as well as in and around calcified nodules, whereas ALP was found in the matrix vesicles, as well as in and around the calcified nodules. Ca tended to localize at the PG sites, while P often mapped to the collagen fibril structures, in the uncalcified matrix. In contrast, Ca/P colocalization was visible in and aroundthe calcified nodules, where ALP and smaller CB-positive structures were observed. The difference in the localization patterns of Ca and P in uncalcified areas may limit the local [Ca2+][PO43-] product, leading to the general inhibition of hydroxyapatite crystallization. The downsizing of CB-positive structures suggested enzymatic fragmentation of PGs. Such structural alterations mould contribute to the preservation and transport of calcium. ALPpossesses the ability to boost local phosphate anion concentration. Therefore, structurally altered PGs and ALP may cooperate in Ca/P colocalization,thus promoting bone calcification.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/09/20 alle ore 09:13:46