Bone Abstracts

There is a similarity of the mechanisms of physiological and pathological mineralization. Pathological calcification of soft tissues as the case of vascular calcification is characterized by the deposition of hydroxyapaptite induced by matrix vesicles at least in the initial stage as in the case of physiological calcification in skeletal tissues. Lipid metabolism is involved in the differentiation of smooth muscle cells and bone cells suggesting that phospholipases can modulat...

Bone cells control initial steps of mineralization by forming matrix vesicles (MVs) in which calcium and phosphate ions are accumulated. Under physiological conditions, MVs are released to the extracellular matrix (ECM) and Ca2+ and Pi form hydroxyapatite (HA). Growing minerals break the MVs membrane and are deposited in ECM. Under pathological conditions the mineralization process becomes deregulated, which leads to the formation of calcium phosphate deposits. It is suggested...

Up to now, most of standard methods for measuring inorganic phosphate (Pi) to determine phosphatase activity are based on coupled enzyme assays, colorimetric methods or conductance measurements. However, none of these methods can measure Pi, substrate and protein concentrations simultaneously, allowing direct kinetic determinations of phosphatase activity in cells in a single assay. Among the enzymes having a pyrophosphatase activity and releasing Pi...

Deficiency in tissue nonspecific alkaline phosphatase (TNAP) causes hypophosphatasia (HPP), which is mainly characterized by skeletal hypomineralization. TNAP promotes mineralization by dephosphorylating the mineralization inhibitor inorganic pyrophosphate (PPi), which is generated from adenosine triphosphate (ATP) by ectonucleotide pyrophosphatase phosphodiesterase 1 (NPP1). Chronic recurrent multifocal osteomyelitis (CRMO), a sterile bone auto-inflammatory disease, has been ...