Electron microprobe investigations into the process of hard tissue formation

Nicholson, W. A. P.; Ashton, Brian A.; Höhling, H. J.; Quint, P.; Schreiber, James H.; Ashton, I. K.; Boyde, A.

doi:10.1007/bf00220309

Cited by 40 publications

(20 citation statements)

References 23 publications

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“…The concentration for half‐maximal response [Ca 2+ ] 1/2 was estimated as ∼1.3 mM, and is comparable to the value found in osteoclasts (55,56) yet differs from that of parathyroid cells, (58) perhaps suggesting homogeneity among cells directly involved in formation of mineralized tissue. Moreover, this value falls within the expected range of calcium concentrations that the odontoblast might be exposed to during mineralization of the dentin matrix (14,15) . Typically, the response to extracellular calcium was reproducible, and a similar response, both in magnitude and time course could be evoked a second or even third time.…”

Section: Discussionsupporting

confidence: 63%

Extracellular Ca2+ Increases Cytosolic Free Ca2+ in Freshly Isolated Rat Odontoblasts

Guo

Davidson

1999

Journal of Bone and Mineral Research

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Recent evidence suggests that extracellular Ca2+ may modulate cell function in mineralized tissue. To determine whether dentinogenic cells, in particular, are sensitive to extracellular Ca 2+ , fura-2 microfluorometry was used to monitor intracellular calcium levels in odontoblasts freshly isolated from rat incisor. In response to applications of 0.5-4.0 mM extracellular calcium (CaCl 2 ), most odontoblasts (84%; 107/128) showed an increase in intracellular calcium. For the majority of these cells (70%; 75/107), the typical response was biphasic; there was an initial, transient increase in intracellular calcium which reached peak levels within 30-50 s and decayed rapidly, followed by a slower (> 300 s) recovery toward basal levels. In general, the response of these cells to calcium was repeatable and the mean calcium concentration for the half-maximal response was ∼1.

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Section: Discussionsupporting

confidence: 63%

Extracellular Ca2+ Increases Cytosolic Free Ca2+ in Freshly Isolated Rat Odontoblasts

Guo

Davidson

1999

Journal of Bone and Mineral Research

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“…Nicholson et al [35] reported that the content of GAGs was lower in rat incisor dentin than in predentin and that a decrease in sulfate levels occurred after the mineralization front. There was also evidence of a loss of GAG during the mineralization of bone [36,37].…”

Section: Discussionmentioning

confidence: 97%

Establishment and Characterization of a Culture System for Enzymatically Released Rat Dental Pulp Cells

Yokose

Kadokura

Tajima

et al. 2000

Calcified Tissue International

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To establish a cell culture system that reflects the dentin formation in dental pulp tissue, we used dental pulp cells enzymatically isolated from rat incisor teeth. During the 20-day culture period, the cells exhibited various phenotypes of the odontoblast differentiation process, from the immature stage to the terminal mineralization stage. The cells began to form the mineralized nodules from day 10, and the nodules became larger by day 20. Alkaline phosphatase (ALP)-positive cells surrounded the mineralized nodules. The ALP activity in the cell layers was maximal on day 5, and gradually decreased to day 20. The calcium content in the cell layers was very low by day 10, and significantly increased from day 15. Sulfated glycosamino-glycans (GAGs) contained in the cell layers increased by day 15, but the content then decreased by day 20. The dental pulp cells produced a small amount of osteocalcin that was released into the culture medium by day 10, and the amount secreted increased markedly from day 15. The expression of osteocalcin and parathyroid hormone/parathyroid hormone-related peptide (PTH/PTHrP) receptor mRNA was evident as early as day 5, and the expression of each gradually increased with the number of days in culture. Dentin matrix protein (Dmp1) mRNA gene transcripts were identified by use of the reverse transcription polymerase chain reaction (RT-PCR) in the cells throughout the culture period. The present results demonstrate that this culture system is useful for studying the differentiation process of the odontoblast-like cells.

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“…The present study has been extended further by analyzing 35 OI bone specimens and 25 age-and sitematched normal controls. Furthermore, cryoprocessing avoids artifactual demineralization that may possibly occur during tissue processing [18][19][20][21] and ultramicrotomy [22]. This is the first report on Ca/P ratios determined on cryosections of OI and normal bone, and the first one to express them separately according to clinical types.…”

Section: Discussionmentioning

confidence: 99%

Abnormal Mineral Composition of Osteogenesis Imperfecta Bone as Determined by Electron Probe X-ray Microanalysis on Conventional and Cryosections

1999

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Osteogenesis imperfecta (OI) is a genetic disorder of the connective tissue characterized by frequent bone fractures. The cause of bone fragility is still unknown even though substantial work on collagen has been done. We measured the calcium to phosphorus ratio (Ca/P) of bone mineral from 35 OI bone samples and 25 age- and site-matched control specimens, using electron probe X-ray microanalysis in the transmission electron microscope. Ultra-thin cryosections and conventionally prepared resin sections were used. Cryo-ultramicrotomy avoids any possible artifactual demineralization that may occur in conventional aqueous media. The Ca/P ratio obtained by these two methods was compared and there was no statistical difference between them. The results were differentiated according to the clinical types of OI for the first time. The Ca/P ratio of OI bone mineral was lower than normal in both resin and cryosections, and mirrored the severity of the disease. OI type II had the lowest ratio (Ca/P = 1.49) compared with normal age- and site-matched controls (Ca/P = 1.69). This abnormal mineral composition in OI type II could be a contributory factor to bone fragility in OI bone.

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Electron microprobe investigations into the process of hard tissue formation

Cited by 40 publications

References 23 publications

Extracellular Ca2+ Increases Cytosolic Free Ca2+ in Freshly Isolated Rat Odontoblasts

Extracellular Ca2+ Increases Cytosolic Free Ca2+ in Freshly Isolated Rat Odontoblasts

Establishment and Characterization of a Culture System for Enzymatically Released Rat Dental Pulp Cells

Abnormal Mineral Composition of Osteogenesis Imperfecta Bone as Determined by Electron Probe X-ray Microanalysis on Conventional and Cryosections

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