Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Osteogenin was recently purified and the amino acid sequences of tryptic peptides were determined. Osteogenin in conjunction with insoluble collagenous bone matrix induces cartilage and bone formation in vivo. To understand the mechanism of action of osteogenin, we examined its influence on periosteal cells, osteoblasts, fibroblasts, chondrocytes, and bone marrow stromal cells in vitro. Osteogenin stimulated alkaline phosphatase activity and collagen synthesis in periosteal cells. The cAMP response to parathyroid hormone in periosteal cells was increased by osteogenin. In primary cultures of calvarial osteoblasts, osteogenin stimulated alkaline phosphatase activity, the cAMP response to parathyroid hormone, and the synthesis of collagenous and noncollagenous proteins; however, cell proliferation was not affected. Osteogenin increased the production of sulfated proteoglycans in fetal rat chondroblasts and in rabbit articular chondrocytes. The present experiments demonstrate the significant influence of osteogenin in the stimulation of osteogenic and chondrogenic phenotypes in vitro.
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PMID:Stimulation of the expression of osteogenic and chondrogenic phenotypes in vitro by osteogenin. 255 30

Hydroxyapatite (HA) and Demineralized Bone Matrix (DBM) are being investigated as potential osteogenic agents with hopes that these substances can be used to induce bone formation in non-union fractures. This study was done to determine the relative effects of HA and DBM implanted as moldable phospholipid composites in bone defects that result in non-unions. We studied 22 ten-month-old Long-Evans male rats with 5.0 mm unilateral radial defects implanted with HA, DBM, and a combination of both substances. Control defects were left unfilled. Eight weeks after implantation, the histological sections demonstrated a decrease in bone formation with HA relative to controls. The HA crystals were encapsulated by connective tissue stroma made up of collagenous elements, fibroblasts, and blood vessels. There were no indications of bone formation within the fibrous stroma. 45Calcium, alkaline phosphatase, and bone gla protein (BGP) assays demonstrated a 16% increase in bone formation in rats implanted with DBM, an 80% decrease in groups implanted with HA (p = 0.01) and an 80% decrease with DBM plus HA (p = 0.01). Radiologic analysis corresponds well with histological and biochemical results. We conclude that osteogenesis in non-union defects is enhanced by the implantation of DBM, while HA interferes with bone formation in the rat model. In the presence of both substances, HA appears to impede new bone growth, negating any positive effects seen with DBM.
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PMID:Osteogenesis in bone defects in rats: the effects of hydroxyapatite and demineralized bone matrix. 255 16

The purpose of this histologic and biochemical study was to assess the osteogenic potential of bone inductive proteins complexed with coralline hydroxylapatite as the carrier vehicle after implantation in an extraskeletal site of the rat. Inductive proteins were extracted from bovine demineralized bone. Implants were placed in 16 male, 3-month old Long-Evans rats (200-300 grams), using paired subcutaneous sites overlying the ventral thorax. There were four experimental groups, with eight implants per group. These included hydroxylapatite alone (HA), hydroxylapatite with inductive protein (HA + P), inactive demineralized bone matrix with (IBM + P), and without inductive protein (IBM). All implants were harvested at 21 days. Findings indicate a lack of osteogenic potential in groups HA, HA + P, and IBM. However, when HA and HA + P were compared, there was a 79% increase in standardized field mean nuclear point counts in the HA + P group. Also, compared to the other three implant groups, controls of IBM + P histomorphometrically showed chondroid bone formation and increased alkaline phosphatase activity. In this model system it may be concluded that with a composite system of coralline hydroxylapatite and bovine-derived inductive protein, bone formation was not seen; positive controls consisting of IBM + P demonstrated a statistically significant increase in AP activity with corresponding histologic evidence of bone formation.
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PMID:Histologic evaluation of bone inductive proteins complexed with coralline hydroxylapatite in an extraskeletal site of the rat. 256 15

The full length cDNA of rat alkaline phosphatase (AP) was placed under the control of the SV40 early promoter. This plasmid was transfected by the calcium phosphate method into AP negative ROS 25/1 cells. Ten clones with AP specific activities ranging between 0.1-2 mumole/min/mg were isolated by cotransfection with the plasmid pSV2Neo, which renders the cells resistant to the antibiotic G418. Two clones with different AP specific activities: C (0.01 mumole/min/mg) and S (2.0 mumole/min/mg) and the osteoblastic ROS 17/2.8 cells (2.0 mumole/min/mg), were examined for their ability to mineralize. In vitro mineralization was tested by culturing cells in alpha-MEM containing 10% fetal bovine serum and 50 micrograms/ml ascorbate in the presence or absence of 10 mM beta-glycerophosphate. Mineralized deposits were observed in all cultures of the S clone and ROS 17/2.8 cells in the presence of beta-glycerophosphate, but not in C clones. Measurement of calcium and phosphorus levels in cells correlated with AP levels of transfected cells. However, extent of mineral accumulation in the transfected ROS 25/1 cells differ from the osteogenic ROS 17/2.8 cells. This finding indicates that high levels of AP may be a necessary constituent for the mineralization process together with other factors yet to be identified.
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PMID:Alkaline phosphatase cDNA transfected cells promote calcium and phosphate deposition. 259 68

Postmenopausal women lose bone mineral density and this loss can be prevented by estrogen administration. Although the skeletal effects of estrogens have been regarded previously as indirect, estrogen receptors have been discovered in cultured human osteoblasts and related cell lines. The UMR106 cell line derived from a rat osteogenic osteosarcoma is such an osteoblast model. We have shown direct effects of estradiol (E) on these cells in vitro, inhibiting growth and stimulating alkaline phosphatase activity (AP) corrected for cell number. This response was maximal at E conc. of 10(-10) M in serum and Phenol Red free medium, was metabolite specific and cell cycle-dependent. These cells contain high affinity binding sites with a Kd of 0.5 nM. Estrogen receptors were detected by the monoclonal antibody H-222 on Western blot after initial immunoprecipitation to concentrate the proteins. E treatment increased several enzymes including creatine kinase and LDH isoenzymes along with increments in intracellular transferrin. Transforming growth factor-beta is secreted by these cells. Secretion of this peptide was stimulated by E. TGF-beta mediated the transient growth inhibition associated with E treatment. Insulin like growth factors (IGF) are also secreted by these cells with IGF-II concentrations in the culture medium being eight times higher than IGF-I levels. E treatment increased the concentrations of both IGFs in the culture medium after a 3 day incubation. Exposure of E treated cells manifested a mitogenic response and reduced AP, indicating that E induced receptors for IGFs. These findings establish direct effects of E on osteoblastic cells in vitro and demonstrate responses to E at many levels. These osteoblast responses in vitro suggest an important role for sex steroids in the development and function of the osteoblast lineage.
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PMID:Estrogens and the skeleton: cellular and molecular mechanisms. 262 18

A monoclonal antibody of immunoglobulin class G1 has been produced which reacts with a high molecular weight antigen apparently present exclusively in osteogenic tissues. Immunohistochemical studies have shown that the antigen is present throughout the mineralized matrix and in osteoid. None of the other tissues examined namely liver, intestine, kidney, spleen, thymus, heart, lung, skin, cartilage and skeletal muscle showed evidence of specific antibody binding. Immunohistochemical staining was also demonstrated in tissues developing from rabbit marrow cultured in vitro and in diffusion chambers in vivo. Temporal studies of antigen expression in the chambers indicated that the antigen occurs at sites of bone formation after the appearance of alkaline phosphatase but before the formation of a mineralized matrix. The results of these studies suggest that the monoclonal antibody recognises a product of differentiated osteoblasts. This antibody may therefore prove useful in studies of osteogenic differentiation.
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PMID:Immunohistochemical studies using BRL 12, a monoclonal antibody reacting specifically with osteogenic tissues. 263 Jan 75

An experimental study of biocompatibility for ceramic material was undertaken in dogs. We used 8 implants and 1 filling-up material in the alveolar bone. A regular radiographic control of the good coaptation and tolerance of these implants was done after various intervals. The sacrifice was performed at 3 and 7 months after the implantation. The good coaptation between alveolar bone and implant was demonstrated by means of different morphological methods. Thus, microradiographs of anatomical specimens, routine histological study following decalcification, analysis of some specimens without decalcification showed the tight coaptation between implant and alveolar bone, without any foreign-body granuloma or allergic reaction. Besides, by transmission and scanning electron microscopy, we could identify the various types of cells (macrophages, fibroblasts and osteoblasts) noted at the interface of the implant matrix at various intervals after the operation. By histoenzymological methods, we also tested the functional activity of these cells, peculiarly their possible osteogenic ability (alkaline phosphatase and ATPase highly positives in some of these cells).
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PMID:[Implants of fired ceramics in the dog. Preliminary study. Morphology of bone coaptation after 3 and 7 months]. 264 74

We have demonstrated via marrow stromal cell cultures and the osteoinductive response to demineralized bone grafts (DBM) that the cortical bone deficit in the ovariectomized (OVX) rat (6 weeks postop) is primarily due to impaired osteoprogenitor cell proliferation, and that dihydrotachysterol (DHT) treatment can be protective. In cultured marrow stromal cells from OVX rats, short-term DHT-Rx exaggerated the already subnormal pattern of marrow stromal cell proliferation. However, in DBM grafts, DHT treatment benefited the time-course of mesenchymal cell DNA synthesis as measured by tritiated thymidine incorporation and osteogenic cell maturation as measured by alkaline phosphatase concentration, and established a suggestive trend toward normalization of bone formation/mineralization (24 h 45Ca incorporation). The data from this animal model infer that DHT could moderate the bone loss normally seen in ovariectomized rats via an activation of the osteoprogenitor cell population.
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PMID:Effect of dihydrotachysterol on bone induction in ovariectomized rats. 265 78

Numerous reports have appeared in the literature indicating phenotypic heterogeneity among cells of the osteoblastic lineage. This diversity may be due to either certain stages of differentiation or a subspecialization of already terminally differentiated osteoblasts. To obtain answers to this question, we report on studies undertaken to clone bone cell populations from 1 day postnatal rat calvaria which express well defined differences in phenotype. To achieve this goal, we have used the soft agarose cloning technique which previously has almost exclusively been applied to clone cells of neoplastic origin. The reason for being able to employ this method is based on the fact that bone cells can be induced by transforming growth factor-beta to reversibly acquire the transformed phenotype, an event expressed by anchorage-dependent bone cells to form progressively growing colonies in soft agarose. Individual colonies, harvested from agarose, were expanded to clonal bone cell populations. Characterizing 48 cell clones by detection of osteoblastic cell markers such as alkaline phosphatase activity, PTH- and prostaglandin-E2-induced adenylate cyclase activity, osteocalcin mRNA synthesis, as well as collagen synthesis, 7 subsets of osteoblastic cell types were identified. Each subset was found to express a distinct phenotype, indicated by the absence or presence of osteoblastic cell markers. Some clones, previously found not to exhibit any osteoblastic traits, developed PTH responsiveness when treated with insulin-like growth factor-I/transforming growth factor-beta, suggesting that these clones may originate from the osteoprogenitor cell pool. While most clonal cell populations were characterized as fully functional osteoblastic cells, some clones expressed merely 1, 2, or 3 osteoblastic markers, which suggests that they may represent stages of differentiation along the osteogenic pathway. In addition, other subclones displayed the capacity to synthesize osteocalcin and showed PTH and prostaglandin-E2 responsiveness, but were found to be devoid of alkaline phosphatase activity. Others expressed all osteoblastic cell markers except PTH responsiveness. The phenotypic constellation of the latter suggests that these cell clones may represent mature osteoblast-like cells, which, perhaps due to environmental circumstances present at the time of isolation, have become altered in accordance with the physiological requirements of the tissue.
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PMID:Evidence for heterogeneity of the osteoblastic phenotype determined with clonal rat bone cells established from transforming growth factor-beta-induced cell colonies grown anchorage independently in semisolid medium. 267 79

The role of basic fibroblast growth factor (bFGF) in the proliferation and differentiation of rat bone marrow cells in culture was studied. bFGF stimulated [3H]thymidine incorporation into these cells by 4-fold at a concentration of 0.3 ng/ml and half-maximal effect was observed at a concentration of 15 pg/ml. In addition to its mitogenic effect, bFGF stimulated alkaline phosphatase activity by 3.6-fold. Continuous treatment with bFGF (for 21 days) resulted in a 6.3-fold increase in the culture dish surface area covered by bone-like mineralized tissue. Maximal bone-like tissue formation was observed in the presence of 3 ng/ml bFGF with half-maximal effect at a concentration of 0.3 ng/ml. These results indicate the possible role of bFGF in the proliferation of osteogenic rat bone marrow cells and their differentiation into cells of osteoblast-like phenotype.
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PMID:Basic fibroblast growth factor enhances the capacity of bone marrow cells to form bone-like nodules in vitro. 275 55


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