Amorphous to crystalline calcium phosphate phase transformation at elevated pH

1982 ◽  
Vol 89 (1) ◽  
pp. 257-267 ◽  
Author(s):  
John L Meyer ◽  
Cecilia C Weatherall
Keyword(s):  
Phase Transformation ◽  
Calcium Phosphate ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

Evidence of calcium phosphate supersaturation in the loop of Henle

1996 ◽  
Vol 270 (4) ◽  
pp. F604-F613 ◽  
Author(s):  
J. R. Asplin ◽  
N. S. Mandel ◽  
F. L. Coe
Keyword(s):  
Calcium Phosphate ◽  
Calcium Concentration ◽  
Loop Of Henle ◽  
X Ray ◽  
Ion Interactions ◽  
Collecting Ducts ◽  
Phosphate Phase ◽  
Dietary Phosphate ◽  
Calcium Phosphate Phase

We have used published rat micropuncture data to construct a matrix of ion concentrations along the rat nephron. With an iterative computer model of known ion interactions, we calculated relative supersaturation ratios in all nephron segments. The collecting ducts and urine showed expected supersaturation with stone-forming salts. Fluid in the thin segment of the loop of Henle may be supersaturated with calcium carbonate and calcium phosphate under certain conditions. Because calculations cannot predict the actual course of crystallization, we made solutions to mimic, in vitro, presumed conditions in the loop of Henle. The solid phases that formed were analyzed by X-ray powder diffraction, electron microprobe, and infrared spectroscopy. All samples were identified as poorly crystallized or immature apatite. The descending limb of Henle's loop creates a unique condition as it extracts water but not sodium, bicarbonate, calcium, or phosphate, giving a calcium concentration at the bend of 3 mM, pH 7.4, and a phosphate concentration that varies from 0.8 to 48 mM, depending on parathyroid hormone and dietary phosphate. We conclude that conditions in the thin segment potentially could create a solid calcium phosphate phase, which may initiate nucleation of calcium oxalate salts in the collecting ducts, potentiating nephrolithiasis and nephrocalcinosis.

The uptake of strontium by calcium phosphate phase formed at an elevated pH

1996 ◽  
Vol 204 (2) ◽  
pp. 363-370 ◽  
Author(s):  
S. Raičević ◽  
Ž Vuković ◽  
T. L. Lizunova ◽  
V. F. Komarov
Keyword(s):  
Calcium Phosphate ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

Stabilizing amorphous calcium phosphate phase by citrate adsorption

CrystEngComm ◽  
2014 ◽  
Vol 16 (10) ◽  
pp. 1864-1867 ◽  
Author(s):  
Yan Chen ◽  
Wenjia Gu ◽  
Haihua Pan ◽  
Shuqin Jiang ◽  
Ruikang Tang
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Phase ◽  
Amorphous Calcium Phosphate ◽  
Surface Reaction ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

Citrate controls nucleation by association with a precursor amorphous phase, which inhibits the surface reaction for nucleation.

Probable Phase Composition of the Mineral in Bone

1980 ◽  
Vol 35 (5-6) ◽  
pp. 357-362 ◽  
Author(s):  
F. C. M. Driessens
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Bone Mineral ◽  
Experimental Error ◽  
Human Bone ◽  
Apatite Structure ◽  
Phosphate Phase ◽  
Limits Of Error ◽  
Calcium Phosphate Phase ◽  
Citrate Ions

Abstract Formulas proposed for the mineral of bone were reviewed. Literature data were collected where Ca, P, Na, Mg and CO3 are determined in the same samples. These data were analyzed for their conformity to the above mentioned formulas. According to this analysis Mg is contained in a phase having the Ca/P of magnesium whitlockite within the limits of error. Na is contained in a carbonated calcium phosphate phase which in analogy with synthetic systems must have the apatite structure. The Ca/P ratio of the remaining "rest phase" is 2. This is based on the composi­ tion of 101 bone mineral samples taken from fishes, reptiles, amphibians, birds and mammals. The CO3 content of the bone samples agrees with the formula Ca8 (PO4)4 (CO3) (OH)2 · x H2O for the "rest phase" within the limits of experimental error. Such a compound has, however, not been found in synthetic systems. Human bone contains about 15% magnesium whitlockite, 25% of the Na and CO3 containing apatite and the rest is the carbonated calcium phosphate with Ca/P = 2. It is presumed that this compound has a structure similar to that of octo calcium phosphate and that most of the citrate ions which always occur in bone mineral samples are in­ corporated in that phase.

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