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.

Bioresponsive phosphoester hydrogels for bone tissue engineering.

Abstract: Bioresponsive and intelligent biomaterials are a vehicle for manipulating cell function to promote tissue development and/or tissue engineering. A photopolymerized hydrogel based on a phosphoester- poly(ethylene glycol) polymer (PhosPEG) was synthesized for application to marrow-derived mesenchymal stem cell (MSC) encapsulation and tissue engineering of bone. The phosphor-containing hydrogels were hydrolytically degradable and the rate of degradation increased in the presence of a bone-derived enzyme, alkaline phosphatase. Gene expression and protein analysis of encapsulated MSCs demonstrated that PhosPEG-PEG cogels containing an intermediate concentration of phosphorus promoted the gene expression of bone-specific markers including type I collagen, alkaline phosphatase, and osteonectin, without the addition of growth factors or other biological agents, compared with pure poly(ethylene glycol)-based gels. Secretion of alkaline phosphatase, osteocalcin, and osteonectin protein was also increased in the PhosPEG cogels. Mineralization of gels increased in the presence of phosphorus in both cellular and acellular constructs compared with PEG gels. In summary, phosphate-PEG-derived hydrogels increase gene expression of bone-specific markers, secretion of bone-related matrix, and mineralization and may have a potential impact on bone-engineering therapies.

Studies on single alkaline phosphatase molecules : reaction rate and activation energy of a reaction catalyzed by a single molecule and the effect of thermal denaturation : the death of an enzyme

Abstract: Single molecules of alkaline phosphatase are captured in a capillary filled with a fluorogenic substrate. During incubation, each enzyme molecule creates a pool of fluorescent product. After incubation, the product is swept through a high-sensitivity laser-induced fluorescence detector; the area of the peak provides a precise measure of the activity of each molecule. Three studies are performed on captured enzyme molecules. In the first study, replicate incubations are performed on the same molecule at constant temperature; the amount of product increases linearly with incubation time. Single enzyme molecules show a range of activity; the most active molecules have over a 10-fold higher activity than the least active molecules. In the second study, replicate incubations are performed on the same molecule at successively higher temperatures. The activation energy of the reaction catalyzed by a single molecule is determined with high precision. Single enzyme molecules show a range of activation energy; micr...

High glucose increases the expression of Cbfa1 and BMP-2 and enhances the calcification of vascular smooth muscle cells

Abstract: Background. Vascular calcification is common in diabetes but the pathogenesis is poorly understood. Methods. To investigate the pathogenesis, we first examined the histology of inferior epigastric arteries from diabetic and non-diabetic patients undergoing a renal transplant. To examine the role of hyperglycaemia, bovine vascular smooth muscle cells (BVSMCs) were incubated with normal (5 mM) or high glucose (25 mM) for 48 or 72 h. Results. The results demonstrated that diabetic patients, compared with non-diabetic patients, had significantly greater calcification and increased expression of the bone matrix proteins osteopontin, type I collagen, bone sialoprotein and alkaline phosphatase (ALP). The in vitro studies demonstrated that high glucose increased the expression of the osteoblast transcription factor core binding factor alpha subunit 1 (Cbfa1) and its downstream protein osteocalcin by 1.9-fold and 1.8-fold, respectively, and ALP activity by 1.5-fold. These findings were blunted in the presence of an inhibitor to protein kinase C. High glucose also significantly enhanced calcification in BVSMC in a time-dependent manner (2.20 � 0.50 vs 1.35 � 0.55mmol/mg, day 7; 5.04 � 1.35 vs 3.12 � 0.92mmol/mg, day 14; P < 0.05). High glucose also induced the secretion of bone morphogenetic protein-2, a known osteoinductive factor, and further increased the secretion normally seen during calcification by 43% at day 7 and 57% at day 14. Conclusions. These results demonstrate that vascular calcification in patients with diabetes is a cell-mediated process characterized by a phenotypic change of VSMCs to osteoblast-like cells with increased bone matrix protein expression, and that hyperglycaemia may directly induce these changes.