Oxalate calcium phosphate deposition

The terminology used to describe conditions associated with prominent renal calcium deposits dismisses the importance of the phosphate anion. Renal parenchymal injury with prominent calcium oxalate deposition is referred to as oxalate nephropathy. Oxalate nephropathy is seen in the setting of primary hyperoxaluria or enteric hyperoxaluria secondary to fat malabsorption. Renal parenchymal injury with abundant calcium phosphate deposits is referred to as... 

For example, normal urine is supersaturated with calcium oxalate. To prevent formation of renal calculi (stones)719 an inhibitory glycoprotein is present and slows the formation and growth of crystals.720 Under some disease conditions calcium carbonate stones may form in pancreatic ducts. A17 kDa lectinlike glycoprotein called lithostatine has been proposed to inhibit stone formation by binding to certain planes on CaC03 microcrystals just as antifreeze proteins (Box 4-D) inhibit ice formation.721 However, this proposed function for lithostatine is doubtful.722 723 Pathological deposits of crystalline calcium pyrophosphate and basic calcium phosphates are sometimes present in joints,724 even in Neanderthal skeletons.725... 

Renal parenchymal calcium deposition can be associated with significant renal dysfunction. When calcium deposits are encountered on renal biopsy, the calcium salt typically contains either phosphate or oxalate. The two anions are easily differentiated pathologically, as calcium oxalate is identified as refractile crystals under polarized light. In contrast, calcium phosphate is non-polarizable but gives a positive histochemical reaction to the von Kossa stain [16]. 

To the best of our knowledge, only a few studies have attempted to prevent the calcification of HEMA-based hydrogels. It has been reported that introduction of carboxylate anions can either prevent or enhance calcification. Cemy et al. (21) found that copolymers of HEMA with 4 wt% methaciylic acid (MAAc) did not calcify under subcutaneous implantation in a rat for 14 months. A similar result was also observed after the implantation of HEMA/MAAc copolymers in the animal urinary tract (22). Other studies carried out in vitro showed that the presence of carboxylate anions significantly reduced the deposition of calcium phosphate (23) and calcium oxalate (24) on acrylic polymers and certain biopolymers. These findings obviously suggest an inhibitory effect of carboxylate anions on calcification. However, by contrast,... 

The level of calcium in solution will depend upon the presence of precipitating anions, notably phosphate and carbonate. Calcium will precipitate as the phosphate to give hydroxyapatite, Caio(P04)6(OH)2, in bones and teeth, and as the phosphate or carbonate to give other structures, including small crystals, or non-crystalline deposits in cells. Small crystals of calcium carbonate, found in the inner ear of some animals, are responsible for the control of balance. Various calcified tissues result from the precipitation of calcium salts, such as hydroxyapatite in the calcification of the aortic wall, and the oxalate in various stones. 

Bark contains 2-5% inorganic solids of the dry bark weight (determined as ash). The metals are present as various salts including oxalates, phosphates, silicates, etc. Some of them are bound to the carboxylic acid groups of the bark substance. Calcium and potassium are the predominating metals. Most of the calcium occurs as calcium oxalate crystals deposited in the axial parenchyma cells. Bark also contains trace elements, such as boron, copper, and manganese. 

Many physiological anions, including protein, phosphate, citrate, lactate, sulfate, and oxalate, form complexes with calcium ions. Although these anions reduce the concentration of free calcium by complex formation, they do not directly interfere with the measurement of the calcium that is free. Protein deposits on the electrode may act as a divalent cation exchanger, resulting in positive interference with high concentrations of Mg. Older electrodes were sensitive to the concentration of protein in the sample. The newer electrodes use a dialysis membrane or neutral carrier to reduce or eliminate this protein effect. Investiga-... 

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