Alkaline phosphatase

About: Alkaline phosphatase is a research topic. Over the lifetime, 20218 publications have been published within this topic receiving 540547 citations. The topic is also known as: Alkaline_phosphatase & IPR001952.

Calcium and phosphate supplementation promotes bone cell mineralization: implications for hydroxyapatite (HA)-enhanced bone formation.

Abstract: Organic phosphate, in particular beta-glycerophosphate (beta-GP), has been used to induce mineralization in cell culture systems It serves as a source of inorganic phosphate when hydrolyzed by alkaline phosphatase This study examined the effect of supplemental calcium and phosphate as well as the influence of various metabolic inhibitors on mineralization in a rat osteoblast-like cell-culture system Mineralization was induced by supplementation of 18 mM of Ca(+2) and 5 mM of beta-GP or Pi Mineral deposits associated with in vitro mineralization were revealed under SEM and TEM Levamisole (10-100 microM) inhibited alkaline phosphatase activity and effectively reduced mineral formation Actinomycin (500 ng/mL) and cycloheximide (50 microg/mL) also reduced mineral depositions by blocking RNA synthesis and protein synthesis, respectively Levamisole and beta-GP did not appear to influence DNA synthesis Spontaneous precipitation of calcium phosphate mineral was not detected in the culture medium with calcium and phosphate supplements in the absence of cell culture The findings suggest that an elevated concentration of calcium and phosphate is crucial for in vitro mineralization Furthermore, the mineralization process is associated with biologic events rather than with a spontaneous precipitation of calcium phosphate mineral In view of the degradation potential of hydroxyapatite (HA)-coated implants, these results may be a viable indication that HA enhances bone formation through a similar mechanism

Osteoblastic gene expression during adipogenesis in hematopoietic supporting murine bone marrow stromal cells.

Abstract: A growing body of data suggests that the bone marrow stroma contains a population of pluripotent cells capable of differentiating into adipocytes, osteoblasts, and lymphohematopoietic supporting cells. In this work, the murine stromal cell lines BMS2 and +/+ 2.4 have been examined as preadipocytes and adipocytes for evidence of osteoblastic gene expression. Adipocyte differentiation has been quantitated using fluorescence activated cell sorting. Within 7–10 days of adipocyte induction by treatment with glucocorticoids, indomethacin, and methylisobutylxanthine, between 40% to 50% of the cells contain lipid vacuoles and exhibit a characteristic adipocyte morphology. Based on immunocytochemistry, both the adipocytes and preadipocytes express a number of osteoblastic markers; these include alkaline phosphatase, osteopontin, collagen (I, III), bone sialoprotein II, and fibronectin. Based on biochemical assays, the level of alkaline phosphatase expression is not significantly different between preadipocyte and adipocyte cells. However, unlike rat cell lines, dexamethasone exposure causes a dose-dependent decrease in enzyme activity. The steady-state mRNA levels of the osteoblast associated genes varies during the process of adiopogenesis. The relative level of collagen I and collagen III mRNA is lower in adipocyte-induced cells when compared to the uninduced controls. Osteocalcin mRNA is detected in preadipocytes but absent in adipocytes. These data indicate that osteoblastic gene expression is detected in cells capable of undergoing adipocyte differentiation, consistent with the hypothesis that these cell lineages are interrelated. © 1993 Wiley-Liss, Inc.

Acid and alkaline phosphatase dynamics and their relationship to soil microclimate in a semiarid woodland

Abstract: The seasonal dynamics of acid and alkaline phosphatase activity (mg p-nitrophenol released g ˇ1 soil h ˇ1 ), soil water potential and temperature, and the relationship of phosphatase activity to plant and soil microbial processes underneath Juniperus monosperma canopies and Hilaria jamesii-dominated intercanopy areas were studied in a northern Arizona pinyon‐juniper ecosystem. Alkaline phosphatase activity was significantly higher in soils under junipers (126.523.9 mg p-nitrophenol g ˇ1 soil h ˇ1 ) than in intercanopy soils (106.624.0 mg p-nitrophenol g ˇ1 soil h ˇ1 ), and significantly exceeded acid phosphatase activity by a factor of 6. Seasonal high phosphatase activities were up to 2.4 times greater than seasonal lows. Activities were maximal in summer and winter. Juniper soils were cooler than intercanopy soils except during the coldest months of the year, when they were up to 2.78C warmer. Intercanopy soils were up to 6.28C warmer than juniper soils, and had the highest (30.020.38C) and the lowest average temperatures (2.320.28C). Soil microclimate explained as much as 20% of the variation in acid and alkaline phosphatase. Temperature and water potential together were better predictors of phosphatase activity than either one alone. The soil water potential classˇ0.1 MParc >ˇ0.5 MPa was the most frequent best predictor of phosphatase activity, especially alkaline phosphatase. The winter peak in alkaline phosphatase activity is attributed to a buildup of phosphatase released into the soil from dying soil organisms, and the desorption and reactivation of previously accumulated phosphatase. # 2000 Elsevier Science Ltd. All rights reserved.