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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.


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Journal ArticleDOI
TL;DR: TNF alpha stimulates calvarial DNA synthesis which causes an increased number of collagen-synthesizing cells, but TNF alpha has a direct inhibitory effect on osteoblastic function.
Abstract: Tumor necrosis factor (TNF) was studied for its effects on bone formation in cultured rat calvariae TNF alpha at 100-100,000 U/ml stimulated [3H]thymidine incorporation into DNA, an effect that appeared after 24 h of treatment and lasted 96 h Transient (24-h) treatment with TNF alpha increased [3H]proline incorporation into type I collagen 24-72 h after the factor was removed; this effect was DNA synthesis dependent and blocked by hydroxyurea Transient treatment with TNF alpha also increased alkaline phosphatase activity In contrast, continuous treatment with TNF alpha for 48-96 h caused a marked inhibition on [3H]proline incorporation into type I collagen and alkaline phosphatase activity TNF alpha caused a small increase in collagen degradation Lymphotoxin had similar effects to those of TNF alpha In conclusion, TNF alpha stimulates calvarial DNA synthesis which causes an increased number of collagen-synthesizing cells, but TNF alpha has a direct inhibitory effect on osteoblastic function

137 citations

Journal ArticleDOI
TL;DR: A novel ferrocene-derived substrate for the ratiometric electrochemical detection of alkaline phosphatase (ALP) was designed and synthesised and demonstrated to be an excellent electrochemical substrates for the ALP-labelled enzyme-linked immunosorbent assay (ELISA).

137 citations

Journal ArticleDOI
TL;DR: The conditional immortalization of these cells by retroviral transfection with the amphotrophic vector, pZipSV40tsa58, which encodes for a temperature‐sensitive mutant form of the simian virus large T‐antigen, should serve as an excellent tool to study the molecular mechanisms that regulate and select for osteoblast and adipocyte differentiation in humans.
Abstract: Although the differentiation of mature osteoblasts has been well studied, there is still a need for a convenient way to study preosteoblast differentiation. Our laboratory has recently described a method for isolating small numbers of authentic osteoblast precursor cells from human bone marrow (Rickard et al., J Bone Miner Res 11:312-324, 1996). Here we describe the conditional immortalization of these cells by retroviral transfection with the amphotrophic vector, pZipSV40tsa58, which encodes for a temperature-sensitive mutant form of the simian virus large T-antigen. At the permissive temperature of 34 degrees C, the cell lines proliferated, but differentiation was arrested, whereas at the restrictive temperature of 39.5 degrees C, proliferation was decreased and differentiation was induced. As assessed by semiquantitative reverse transcriptase PCR after 4 days of culture at 39.5 degrees C, the six cell lines expressed similar mRNA levels both constitutively and in response to dexamethasone (Dex) and 1alpha,25-dihydroxyvitamin D3 (1,25(OH2)D3) for osteoblast (alkaline phosphatase [ALP], type I collagen [Col I], osteocalcin [OC], and parathyroid hormone receptor [PTH-R] and adipocyte (lipoprotein lipase [LPL]) genes. In the presence of 10(-8) M Dex, gene expression for ALP, PTH-R, and LPL increased, but that for OC decreased. Stimulation with 10(-8) M 1,25(OH2)D3 increased gene expression for ALP, OC, and Col I. Changes in protein production for ALP, OC, and type I procollagen in response to Dex and 1,25(OH2)D3 were similar to changes in mRNA levels. When cultured at 39.5 degrees C with ascorbate and beta1-glycerolphosphate for 21 days, mineralization of matrix occurred, whereas culture with Dex plus 1,25(OH2)D3, or rabbit serum led to enhanced formation of cytoplasmic lipid droplets within 6 days. Thus, these cell lines are capable of bipotential differentiation and should serve as an excellent tool to study the molecular mechanisms that regulate and select for osteoblast and adipocyte differentiation in humans.

137 citations

Journal ArticleDOI
TL;DR: PTH may preferentially stimulate osteoblast differentiation in immature osteoblasts but inhibit it in more mature cells, indicating that PTH exerts opposite effects on the phenotypic expression of osteoblast, depending on their differentiation stages of osteoclasts.
Abstract: The effects of parathyroid hormone (1-34) (PTH (1-34) on osteoblast differentiation were investigated using primary osteoblast-like cells isolated from newborn mouse calvaria. The osteoblast-like cells cultured at low cell densities, in which the cells remained in a subconfluent state at the end of culture, were exposed for 7 days to PTH. This stimulated alkaline phosphatase (ALP) activity in a dose-dependent manner. In contrast, PTH dose-dependently inhibited both ALP activity and osteocalcin production in cells inoculated at high cell densities, in which they had reached a confluent state before the end of culture. The changes of ALP activity by PTH were accompanied with the expression of ALP messenger RNA. PTH induced no changes of the hydroxyproline content in the cell layer when the cells were exposed to the hormone at a subconfluent state, but reduced the content at a postconfluent state. The stimulation of ALP activity by PTH at a preconfluent state was retained even after the removal of PTH from the culture media. The opposite effect of PTH, observed between the preconfluent and the postconfluent state, was reproduced by adding dibutyryl cyclic adenosine monophosphate (cAMP) or forskolin, but not by adding phorbol myristate acetate. In a colony-forming unit fibroblastic (CFU-F) assay, using bone marrow cells isolated from tibiae of 10-week-old mice, PTH induced no changes in the total number of CFU-Fs, but increased the proportion of ALP-positive colonies. These results indicate that PTH exerts opposite effects on the phenotypic expression of osteoblasts, depending on their differentiation stages of osteoblasts. PTH may preferentially stimulate osteoblast differentiation in immature osteoblasts but inhibit it in more mature cells.

137 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
2023795
20221,761
2021271
2020302
2019294