Ultrastructure of Apatite Crystals Formed During Vascular Calcification in Humans

Kakei, Mitsuo; Tanaka, Sakae; Mishima, Hiroyuki; Yoshikawa, Masayoshi

doi:10.2485/jhtb.18.135

Cited by 3 publications

(3 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our Raman analysis, however, revealed that the replacement of OH with F ions did not occur in rat developing enamel (Table I). This finding may be due to 2 different calcification mechanisms whereby the formation of crystal either with CDL or without CDL is strictly regulated by each hard tissue with the except of pathological calcification 44) . One pathway, mediated by the precursor mineral octacalcium phosphate (OCP), may have appeared around the Cambrian period 45) .…”

Section: Comparison Of Enzymatic Activity Between F-and Cd-exposed Enmentioning

confidence: 76%

Aspects Regarding Fluoride Treatment for Reinforcement and Remineralization of Apatite Crystals

Kakei

Tanaka

Yoshikawa

2012

J. Hard Tissue Biology.

Self Cite

View full text Add to dashboard Cite

The purpose of the present study was to investigate whether fluoride (F) ions are really capable of the repair (remineralization) of damaged crystals and useful for reinforcing the quality (i.e. modify the crystal structure) of tooth enamel using transmission electron microscopy and Raman microprobe analysis. Additionally, carbonic anhydrase activity was measured in immature enamel tissue to compare the harmfulness of F ions to that of cadmium (Cd) ions during the process of crystal nucleation by means of differential gas pressure analysis. Electron micrographs indicated no signs of remineralization of artificially damaged crystals after incubation in a remineralizing solution and further revealed that treatment with acidulated phosphate fluoride (APF) gel caused crystal dissolution rather than crystal improvement. Regarding crystal structure modification, Raman microprobe analysis revealed that no up-shift of PO 4 3-ν 1 band assigned to human sound enamel crystals occurred when APF gel was used. Furthermore, fluorapatite crystals were not generated by daily intake of F ions in developing rat tooth enamel. A differential gas pressure method demonstrated that the harmfulness of F exposure during the nucleation process of calcified hard tissues was much greater than that of Cd exposure. These results demonstrate that F treatments have no effect on improving crystal quality or remineralization and are inconsistent with the purpose of public health.

show abstract

Section: Comparison Of Enzymatic Activity Between F-and Cd-exposed Enmentioning

confidence: 76%

Aspects Regarding Fluoride Treatment for Reinforcement and Remineralization of Apatite Crystals

Kakei

Tanaka

Yoshikawa

2012

J. Hard Tissue Biology.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The stomas present in the surface layer, which were considered to be the marks of odontoblast processes, disappeared during the fossilization. The crystals of dentin and bone possess the CDLbearing crystals [18][19] . Kakei et al reported that the microstructure of apatite crystals might remain considerably stable during the course of fossilization [20][21] .…”

Section: Discussionmentioning

confidence: 99%

Nature of Apatite Crystals in the Tooth of <i>Eusthenopteron</i> from Devonian

Mishima

Kakei

Sasagawa

et al. 2017

J. Hard Tissue Biology.

Self Cite

View full text Add to dashboard Cite

Eusthenopteron come under the rhipidistians. Little information is available regarding the ultrastructure and properties of tooth in Eusthenopteron. The purpose of the present study is to examine the nature of apatite crystals in the tooth of Eusthenopteron. Backscattered electron image of SEM revealed the tooth consisted of two layers, tentatively named as the bright surface layer and the dark inner dentin layer, respectively. The surface layer was more calcifi ed than the inner dentin layer. The incremental lines were not observed in the surface layer. Narrow dentinal tubules were confi rmed in the inner dentin layer. TEM study demonstrated the crystals of surface layer were not bearing the central dark lines (CDL-free type) in its structures. By contrast, the crystals of the inner dentin layer possessed the central dark lines (CDL-bearing type). X-ray diff raction analysis suggested that the crystal was fl uorapatite in the surface layer, and a mixture of hydroxyapatite and fl uorapatite in the inner dentin layer. The presence of fl uorapatite in the dentin was estimated to be the infl uence of the fossilization. Using EPMA, F, Al, Si, Ca, and P were detected in the surface layer, and F, Na Mg, Si, Ca, and P were detected in dentin layer. The weight % F of the surface layer was 3.07, and 3.35 in the inner dentin layer. Raman spectrum analysis demonstrated that the phosphate peaks of 965 cm -1 assigned for hydroxyapatite in the inner dentin layer and 967 cm -1 assigned for fluorapatite in the surface layer were detected, respectively. Taking the crystallographic viewpoint and histological feature into consideration, the surface layer was regarded as enameloid and the inner dentin layer was orthodentin including plicidentin.

show abstract

“…The scientific justification for F therapy for osteoporosis, which induced irregular periosteal bone formation, ligament calcification, abnormal mineralization, and an increase of osteoid formation [29][30][31][32][33][34][35][36], is as follows: Concerning the high dose of F treatment, the increase of bone mineral density might be attributed to the pathological mineralization seen by an abnormal calcification and the presence of large crystals located outside the collagen fibrils [16,17,35,37]. This occurs because a high content of F ions absolutely inhibits the synthesis or activity of certain enzymes such as enolase and carbonic anhydrase [13,14,[38][39][40][41][42]. This might be fatal to cellular metabolism and eventually lead to pathological calcification, which might be similar to the vascular calcification accompanying cellular degeneration [43].…”

Section: Discussionmentioning

confidence: 99%

Fluoride Exposure May Accelerate the Osteoporotic Change in Postmenopausal Women: Animal Model of Fluoride-induced Osteoporosis

Kakei¹,

Yoshikawa²

2015

Adv Tech Biol Med

Self Cite

View full text Add to dashboard Cite

Carbonic anhydrase is a key enzyme for initiating the crystal nucleation, seen as "the central dark line" in the crystal structure in calcified hard tissues such as tooth enamel, dentin and bone. Both estrogen deficiency and fluoride exposure adversely affected the synthesis of this enzyme in the calcifying hard tissues. This led to the notion that fluoride exposure might increase the risk of developing osteoporosis in postmenopausal women. Using ovariectomized rats, which represent an estrogen (Es)-deficient state, as an animal model of postmenopausal women, we examined the causal relationship between fluoride (F) exposure and risk of developing osteoporosis. Two groups of rats, an Es-deficient group and a non-Es-deficient group, were administered free drinking water containing F ions (1.0 mg/L). Two other groups, an Es-deficient group and a control-group, were administered tap water. Soft X-ray radiography demonstrated a significant increase of radiolucent areas in the calvaria of the combined Esdeficient plus F group compared to that in the other experimental groups. Electron microscopy revealed an increase of amorphous minerals in the radiolucent areas. Light microscopy demonstrated that combined effects evidently of Es-deficiency and administration of F caused deterioration of the rat tibia with a coarse pattern of trabecular architecture, suggesting that a decline in bone formation might be the primary cause of osteoporosis. Consequently, F exposure might accelerate osteoporotic changes in postmenopausal women even at a low dose.

show abstract

Ultrastructure of Apatite Crystals Formed During Vascular Calcification in Humans

Cited by 3 publications

References 37 publications

Aspects Regarding Fluoride Treatment for Reinforcement and Remineralization of Apatite Crystals

Aspects Regarding Fluoride Treatment for Reinforcement and Remineralization of Apatite Crystals

Nature of Apatite Crystals in the Tooth of <i>Eusthenopteron</i> from Devonian

Fluoride Exposure May Accelerate the Osteoporotic Change in Postmenopausal Women: Animal Model of Fluoride-induced Osteoporosis

Contact Info

Product

Resources

About