Calcium-phosphate ratios

The observed calcium/phosphate ratio of 4.5 at the intercept of the calcium and phosphate retention curves that should minimize the sum of the urine calcium plus urine phosphate losses was difficult to believe in view of both the known Ca/P ratio of bone and the amounts we were adding to these solutions. This disparity between the optimal ratio determined experimentally and what we had assumed this ratio should be on the basis of known body composition is partially reconciled by the experiment of Sutton and Barltrop. They fed preterm infants stable Ca46 and observed that up to 20% of the isotope absorbed was subsequently excreted in the stool. Our infants also were undoubtedly having unmeasured calcium losses from the bile, pancreatic juice and succus entericus secreted into their intestine... 

Demineralization of UF whey retentate as compared to UF whey permeate is generally slowed down by salt and/or proteins that build up onto and in the membranes (Perez et al., 1994). Finally, in the case of skim milk the aim of the ED process is not only to reduce the overall ash content, but also to increase the calcium/phosphate ratio to about 0.77 in skim milk powder used in infant formula (Batchelder, 1987), this goal being much easily achievable by replacing the conventional membranes with selective ones (Andres et al., 1995). 

Tables lO.l to 10.5 may be useful as an orientation and a source of specific information for sections in this chapter. Table 10.1 lists the inorganic nutrients in various foods. One of the more striking aspects of these data is the fact that potassium concentrations in plant foods are much higher than those of sodium. Another point, raised under calcium and phosphate, is that green leafy vegetables (broccoli) and dairy products (cottage cheese) are high in calcium, whereas meats have relatively low levels of this nutrient. The calcium/phosphate ratios of various fcKids are also discussed in this section. These ratios can be easily calculated from the data in the table. Food iron data from tw o sources are listed. Milk and milk products, which contain high levels of many nutrients, are very low in iron.

Ratio of Calcium/Phosphorus in Various Foods Absorption and Excreticm Calcium/Phosphate Ratios Phosphate Tumcrver in tiie Body Osteoporosis... 

Anderson, M. R, Hunt, R. D., Griffiths, H. J., McIntyre, K. W., and Zimmerman, R. E. (1977). Long-term effect of low dietary calcium.-phosphate ratio on the skeleton of Cebus albifrons monkeys. J. Nutr. 107, 834-839. 

Keller, L. and Dollase, W.A. (2000) X-ray determination of crystalline hydroxyapatite to amorphous calcium phosphate ratio in plasma sprayed coatings. /. Biomed. Mater. 

The most common apatite used in medicine and dentistry is hydroxyapatite (HA), a material with a hexagonal crystal lattice an ideal chemical formula, i.e., Ca,o(P04) (OH)2 ideal weight percents of 39.9 percent Ca, 18.5 percent P, and 3.38 percent OH and an ideal calcium-phosphate ratio of 1.67 (Fig. 13.5). The crystal structure and crystallization behavior of HA is strongly dependent on the substitutional nature of the ionic species. 

Skeletal calcium exists in the form of the complex salt, CaCOg. 3Cag(P04)2, and is not in simple equilibrium with the serum calcium. Calcification is a process involving the coaction of several factors, one being the phosphatase enzyme present in plasma and cartilage, another being the maintenance of the optimal calcium-phosphate ratio in the plasma, which normally is such that [Ca] X [PO4] = 36, both being expressed in mg. per 100 ml. of blood. 

Wyshak G and Frisch RE (1994) Carbonated beverages, dietary calcium, the dietary calcium/phosphate ratio, and bone fractures in girls and boys. Journal of Adolescent Health 15 210-215. 

Tricalcium phosphate, Ca2(P0 2> is formed under high temperatures and is unstable toward reaction with moisture below 100°C. The high temperature mineral whidockite [64418-26-4] although often described as P-tricalcium phosphate, is not pure. Whidockite contains small amounts of iron and magnesium. Commercial tricalcium phosphate prepared by the reaction of phosphoric acid and a hydrated lime slurry consists of amorphous or poody crystalline basic calcium phosphates close to the hydroxyapatite composition and has a Ca/P ratio of approximately 3 2. Because this mole ratio can vary widely (1.3—2.0), free lime, calcium hydroxide, and dicalcium phosphate may be present in variable proportion. The highly insoluble basic calcium phosphates precipitate as fine particles, mosdy less than a few micrometers in diameter. The surface area of precipitated hydroxyapatite is approximately... 

Other Ceramic Calcium Phosphate Materials. Other ceramic calcium phosphate materials for repairing bony defect iaclude p-tricalcium phosphate (P-TCP) [7758-87-4], P-Ca2(PO, and biphasic calcium phosphate (BCP) ceramics which consist of both P-TCP and HA. Unlike ceramic HA, P-TCP resorbs ia the tissue (293). The in vivo dissolution of BCP ceramic implants was shown (296) to iacrease with increasing P-TCP/HA ratio ia the implants. Both P-TCP and BCP can lead to new bone growth to various extents depending on the appHcations and the type of materials used (293,296). 

Dissolution of Calculi Model. Dissolved Ions from Ca3(PCf)2. Dissolution of calcium phosphate by macrocyclic polyamines proceeds at pH 7, which is established by measuring the freed cation concentration as well as the freed anion concentration with respect to the control values (Table 7). The molar ratio of [Ca2 + ] to [P04 ]... 

SS/MA may be structured in different ratios of sulfonated styrene to maleic anhydride. Typically, it is 3 1 (20,000 MW) or 1 1 (15,000 MW). The application rates of all calcium phosphate scale/sludge inhibitors or stabilizers vary, based on the amount of calcium present in the cooling system, with increased calcium hardness leading to higher levels of polymer required. 

C04-0146. The largest single use of sulfuric acid is for the production of phosphate fertilizers. The acid reacts with calcium phosphate in a 2 1 mole ratio to give calcium sulfate and calcium dihydrogen phosphate. The mixture is crushed and spread on fields, where the salts dissolve in rain water. (Calcium phosphate, commonly found in phosphate rock, is too insoluble to be a direct source of phosphate for plants.) (a) Write a balanced equation for the reaction of sulfuric acid with calcium phosphate, (b) How many kilograms each of sulliiric acid and calcium phosphate are required to produce 50.0 kg of the calcium sulfate-dihydrogen phosphate mixture (c) How many moles of phosphate ion will this mixture provide ... 

Dietary phosphorus also affects calcium metabolism. Polyphosphate decreases calcium absorption in young men while orthophosphate supplement does not (26J. However, in the rat all forms of phosphate decrease calcium absorption about equally (31). However, widely divergent dietary calcium phosphorus ratios do not seem to affect calcium utilization by people as long as there is adequate phosphorus intake (32). In general phosphorus stimulates calcium retention in man (3277... 

Substituting the original ions of calcium phosphate fluorapatite often leads to changes in the unit-cell parameters. Frequently, the variations of the unit-cell dimensions are proportional to the substitution ratio and follow Vegard s law (i.e. the unit-cell parameter varies linearly with the substitution ratio). This is the case, for example, with chlor-fluorapatite. 

Fluorhydroxyapatite solid solutions can be prepared by the sol-gel method [134,135]. Cheng et al. reported the control of fluoride content in fluorhydroxyapatite solid solutions by the amounts of triethanolamine (N(CH2CH20H)3) and trifluoroacetic acid (CF3COOH) in the mixed ethanol solutions of Ca(N03)2 and P0(CH2CH20H)x(0H)3 x with a Ca/P ratio of 1.67 [134]. After evaporation of the mixed ethanol solution at 150°C on a hot plate, the powder obtained, comprising a homogeneous mixture of calcium nitrate crystallites and amorphous calcium phosphates, is then heated at 500 or 900°C for 1 h to be transformed into the pure apatitic phase. 

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