Pathological calcification

Pathologists frequently find foci of calcification in tisues that normally do not concentrate calcium. Calcium salts may accumulate in abnormal sites either from focal degeneration—dystrophic calcification—or as a consequence of a general disturbance [33, 34] 

The site of calcium accumulation in tissues is readily identifiable on hematoxylin-eosin slides because the protein in the calcified area develops a strong affinity for hematoxylin. But sometimes special stains must be used to identify calcium. Among those techniques, the von Kossa staining method is one of the most popular. The method is based on the precipitation of silver salt by the anionic groups present in the calcium deposit. Calcium can be demonstrated directly either by microincineration or by visualization of the hydroxyapatite crystals with the aid of the electron microscope. 

Dystrophic calcification occurs in two stages calcium deposition and the reaction of the tissue to deposited salts. Again, it is not known what precipitates calcium. It is sometimes assumed that changes in the matrix will lead to crystallization of the calcium salts because the altered matrix acts as a seed or template for hydroxyapatite crystallization. We have seen that in bone the hydroxyapatite crystal is bathed in a supersaturated solution of calcium and phosphorus and serves as a seed for further crystallization of the calcium phosphate salt. 

The occurrence of specific cytoplasmic granules in the osteoclast. J. Ultrastruct. Res. 19, 417-431 (1967) 

Vincent, J. Recherches sur la constitution de I os adulte. Bruxelles Editions Arscia 1955 

The normal areas of mineralisation are bones and teeth but the process occasionally occurs elsewhere in the body. Examples of this are the formation of urinary stones, gallstones and tartar on teeth. 

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G. Daculsi, J.M. Bouler, R.Z. Legeros, Adaptative crystal formation in normal and pathological calcifications in synthetic calcium phosphate and related biomaterials, Int. Rev. Cytol. 172 (1997) 129-191. 

Francis MD, Russell RGG, Fleisch H. Diphosphonates inhibit formation of calcium phosphate crystals in vitro and pathological calcification in vivo. Science, 1969, 165, 1264-1266. 

LeGeros, R.Z., Contiguglia, S.R. and Alfrey, A.C., 1973. Pathological calcifications associated with uremia. Calcif. Tissue Res., 13 173—185. 

Leroux-Berger M, Queguiner 1, Maciel TT et al (2011) Pathologic calcification of adult vascular smooth muscle cells differs on their crest or mesodermal embryonic origin. J Bone Miner Res 26 1543-1553... 

Johnson K, Coding J, Van Etten D et al (2003) Linked defidencies in extracellular PP(i) and osteopontin mediate pathologic calcification associated with defective PC-1 and ANK expression. J Bone Miner Res 18 994-1004... 

Y. (2006) Growth of calcium hydroxyapatite (Ca-HAp) on cholesterol crystals from a simulated body fluid a possible insight into the pathological calcification associated with atherosclerosis. /. Colloid Interface Sci., 295 (2), 348—363. 

Hydroxylapatite Caio(P04)6(OH)2 In an impure form (main impurities COs, Mg and HP04 ) as the mineral in bones and tee. In most pathological calcifications. Pure HAP as a S5mthetic biomaterial... 

Magnesian whitlockite Approximately CaisMg2H2(P04)i4 Dental calculus, urinary and salivary calculi, carious lesions in teeth and other pathological calcifications... 

Bisacylphosphonates (50) and bishydroxyiminophosphonates (51) were found to be the first examples of non-geminal bisphosphonates biologically active in calcium metabolism disorders such as pathological calcification and bone resorption These compounds showed less toxic side-effects and improved bioavailability than bisphosphonates approved for clinical use. ... 

TOXICITY. Normally, the small intestine acts as an effective control and prevents excess calcium from being absorbed. However, a breakdown of this control may raise the level of calcium in the blood and lead to pathological calcification of the kidneys and other internal organs. This may occur in infants who have been fed on artificial foods fortified with excessive amounts of vitamin D and calcium. 

As biogenic apatite where it is the prime constituent of vertebrate tooth and bone, including ivory, fish teeth and pathological calcifications. In this last context, the apatite species present ate fluorapatite and hydroxylapatites plus the calcium carbonate-bearing dahUite (Ca5[P04,C03]30H). 

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