Hydroxyapatite, in bone

Bisphosphonates bind to hydroxyapatite in bone and decrease resorption by inhibiting osteoclast adherence to bone surfaces. All bisphosphonates become incorporated into bone, giving them long biologic half-lives of up to 10 years. 

Binds to hydroxyapatite in bone and inhibits osteoclast-mediated bone resorption... 

Phosphorus is a critically important element in every cell of the body and also in the form of hydroxyapatite in bone and in all other functions as phosphate. The concentration of phosphate in blood is 1.0 to 1.5 mmol/L existing as H2P0( and HPOl" the equilibrium between the two acts as a proton buffer... 

Traditional IR spectroscopy was initially applied to homogenized bone3 to identify the presence of hydroxyapatite in bone and to quantify the presence of bone substituents, such as carbonate and acid phosphate. Because carbonate can substitute for both hydroxyl ions and phosphate ions, IR techniques were developed to distinguish between these two sites for substitution. These spectra also provided... 

The spaces between the ends of the tropocollagen molecules in a collagen fiber (see Fig. 4) are the nucleation sites for the deposition of a form of calcium phosphate, hydroxyapatite, in bone formation. Further hydroxyapatite is added until the nucleation sites grow and join with one another to form the mature bone structure. 

PCP bone hook provides affinity to the hydroxyapatite in bone... 

Inorganic phosphate is a major component of hydroxyapatite in bone, thereby playing an important role in the structural support of the body and providing phosphate for the extracellular and intracellular pool. 

Osteopontin (formerly known as bone sialoprotein I) binds tightly to hydroxyapatite in bone and thus forms an integral part of the mineralised matrix. It has been postulated to be a ligand for the vitronectin receptor, and this suggests a possible role of osteopontin in osteoclast attachment and function (Merry et al., 1993). Hence, it functions as a potent marker of ossification and consequently its expression serves to quantify the degree of mineralisation of bone tissue in contact with bioceramic materials including coatings. 

Phosphorus is required not only as a component of hydroxyapatite in bone, but also as a component of nucleic acids and many other biologically important molecules. Without phosphorus we would have no energy-storage molecules, such as ATP and creatine phosphate, for the energy derived from glycolysis and the citric acid cycle. The RDA for phosphorus is the same as that for calcium. Because it is abundant in most foods, a deficiency of phosphorus in the presence of an otherwise adequate diet is virtually impossible. 

We wish to report some work on the adsorption of acid and alkali-precursor gelatins, the water-soluble products of collagen. The study of both types allowed us to determine whether the differences exhibited by the two kinds in solution are reflected in the adsorbed state, and offers some insight into the state of flexible molecules at interfaces. The use of two dissimilar adsorbents, glass and stainless steel powders, should yield information on segment-surface interactions during the adsorption process. Some effects of added calcium ions were also studied since the Ca-ions of hydroxyapatite in bone and teeth are intimately related to collagen. 

Lead is believed to directly incorporate into the calcium sites in hydroxyapatite in bone. Bone lead levels provide a useful biomarker of long term, cumulative exposure to lead, because the half-life of lead in bone is >10 years... 

Mineral matrix 1) A general term for the inorganic material in a sedimentary deposit. 2) The interlinked mineral structure that forms the hard structure in complex biologically produced hard parts, including hydroxyapatite in bones and teeth, calcite or aragonite in shells and corals, apatite minerals in chitin, etc. 

Phosphorus is a vital element in the composition of all living matter and there is no known organism in which the chemistry of the element is not utilised. The human body contains many thousands of different phosphorus compounds, almost all of which are essential for its proper function. It contains very roughly 1% by weight of the element, about four fifths of this being present as hydroxyapatite in bones and teeth. Phosphorus constitutes about 0.3% of the total weight of the brain, about 0.2%... 

Pamidronate disodium is a bisphosphonate which binds irreversibly to hydroxyapatite in bone. It is a strong inhibitor of bone resorption, reducing osteoclast or osteoclast precursor activity. Bisphosphonates inhibit bone resorption by selective adsorption to mineral surfaces and subsequent internalization by bone-resorbing osteoclasts. 

---