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)

Fragments of cancellous and cortical bone from human maxilla and mandible were cultured by the explant technique. Cells isolated by trypsinization of primary cultures were characterized as osteoblasts on the basis of intracellular alkaline phosphatase activity, the constituents of the extracellular matrix, and response to human parathormone (PTH). In culture, the osteoblasts often gave rise to superposed clumps of large cells whose cytoplasm contained endoplasmic reticulum, numerous mitochondria, vacuoles, and a dense network of intermediate filaments, often at the level of the plasma membrane. In the presence of vitamin C and 1,25-dihydroxyvitamin D3, the osteoblasts produced an extracellular matrix composed of collagen type I and various non-collagenous proteins, including osteocalcin. Biochemical test results were comparable to those reported for osteoblasts of other origins (rat calvaria, human iliac crest), and namely elevated intracellular alkaline phosphatase activity and cAMP accumulation in response to stimulation by human PTH (1-34). Osteoblasts isolated in this manner were cultured in the presence of pure titanium disks to determine the effects of exposure to this metal. Electron microscopy revealed few significant differences in cell growth and specific enzyme activity compared to control osteoblasts grown on plastic dishes, reflecting the excellent biologic and biochemical relationship between the osteoblasts and pure titanium. This experimental system thus appears suitable for biocompatibility studies, and in particular, evaluation of dental implants.
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PMID:Characterization of endosteal osteoblasts isolated from human maxilla and mandible: an experimental system for biocompatibility tests. 136 48

A new bone cell line was established by transfecting normal adult human osteoblast-like (hOB) cells, derived from a 68-year-old woman, with the plasmid pSV3 neo. The plasmid included coding sequences and promotors for the large and small T antigens of the SV40 virus as well as resistance to the antibiotics neomycin and G418. A single antibiotic-resistant colony was located and cloned. Large tumor antigen production in the clonal cell line was confirmed by indirect immunofluorescence study. Treatment with 1,25-dihydroxy-vitamin D3 increased steady-state concentrations of protein and mRNA for osteocalcin and for alkaline phosphatase. Northern blot analyses also demonstrated the presence of mRNAs for alpha(I)-procollagen, osteopontin 1a, transforming growth factor beta, and interleukin-1 beta. The plasma membrane calcium pump and osteonectin were identified by immunocytochemical analysis. These cells produced a matrix that mineralized when beta-glycerophosphate was added to their cultures. As assessed by functional receptor assays, both estrogen and androgen receptors were present and functional, although at low concentrations. Treatment with parathyroid hormone did not stimulate adenylate cyclase activity. Thus, these cells are a well-differentiated, steroid-responsive clonal cell line that closely approximates the phenotype of the mature osteoblast. They should serve as an excellent model for the study of osteoblast biology.
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PMID:Development and characterization of a rapidly proliferating, well-differentiated cell line derived from normal adult human osteoblast-like cells transfected with SV40 large T antigen. 137 29

The MC3T3-E1 mouse calvaria-derived cell line has been used to study the role of collagen synthesis in osteoblast differentiation. MC3T3-E1 cells, like several previously characterized osteoblast culture systems, expressed osteoblast markers and formed a mineralized extracellular matrix only after exposure to ascorbic acid. Mineralization was stimulated further by beta-glycerol phosphate. Ultrastructural observations indicated that the extracellular matrix produced by ascorbic acid-treated cells was highly organized and contained well-banded collagen fibrils. Expression of osteoblast markers followed a clear temporal sequence. The earliest effects of ascorbic acid were to stimulate type I procollagen mRNA and collagen synthesis (24 h after ascorbate addition), followed by induction of alkaline phosphatase (48-72 h) and osteocalcin (96-144 h) mRNAs. Procollagen mRNA, which was expressed constitutively in the absence of ascorbate, increased only twofold after vitamin C addition. In contrast, alkaline phosphatase and osteocalcin mRNAs were undetectable in untreated cultures. Actions of ascorbic acid on osteoblast marker gene expression are mediated by increases in collagen synthesis and/or accumulation because (1) parallel dose-response relationships were obtained for ascorbic acid stimulation of collagen accumulation and alkaline phosphatase activity, and (2) the specific collagen synthesis inhibitors, 3,4-dehydroproline and cis-4-hydroxyproline, reversibly blocked ascorbic acid-dependent collagen synthesis and osteoblast marker gene expression.
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PMID:Relationship between collagen synthesis and expression of the osteoblast phenotype in MC3T3-E1 cells. 137 31

Rat calvaria bone cells isolated by collagenase digestion form a bone-like matrix which mineralizes in vitro in the presence of beta-glycerophosphate, in less than 2 weeks. The purpose of this work was to investigate, in this mineralizing rat osteoblastic cell culture, the synthesis of collagen, osteocalcin, and bone alkaline phosphatase (ALP). The results obtained indicate (1) After 15 days in culture, the extracellular-matrix contains collagen type I, V, and to some extent type III. Metabolic labeling at day 14, during the phase of nodules mineralization as well as new nodules formation, shows that collagen types I and type V are synthesized; (2) During the phase of cell growth, no osteocalcin could be detected in the medium, however, at the point of nodule formation, the osteocalcin level reached values of 3.55 +/- 1.39 ng/ml, followed by a 30-fold increase after nodules became mineralized. At day 14, after metabolic labeling, de novo synthesized osteocalcin was chromatographed on an immunoadsorbing column. With urea-SDS PAGE the apparent molecular weight was determined to be 9,000 daltons. (3) Specific activity of ALP was found to be 10 nmol/min/mg of proteins at cell confluence. At day 15, when nodules are mineralized, this activity was increased by 40-fold. The Michaelis constant was 1.58 10(-3) M/L. ALP was inhibited by L-homoarginine and levamisole but not by L-phenylalanine. ALP was shown to be heat sensitive at 56 degrees C with two slopes of inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of collagen, osteocalcin, and bone alkaline phosphatase in a mineralizing rat osteoblastic cell culture. 137 88

Bone metabolism was investigated in toxic goiter. The authors obtained evidence on high levels of osteocalcin which marks bone formation. The time of the thyroid function recovery during thyrostatic therapy and indices of phosphorus-calcium metabolism disagree indicating delayed normalization of the bone tissue metabolism. There is a correlation between the thyroid function, osteocalcin and oxyproline that indirectly confirms the action of thyroid hormones on the bone matrix; between osteocalcin levels and other indices of bone metabolism (serum alkaline phosphatase activity and oxyproline excretion).
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PMID:[Osteocalcin in diffuse toxic goiter]. 137 70

We report our experience in the follow-up of 63 patients with advanced prostate adenocarcinoma. We used prostate-specific antigen and prostatic acid phosphatase in 27 patients; in 36 patients we evaluated osteocalcin and bone isoenzyme of alkaline phosphatase, two markers of bone metabolism which seem to be good markers in the follow-up of patients with bone metastases.
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PMID:Advanced prostate cancer follow-up with prostate-specific antigen, prostatic acid phosphatase, osteocalcin and bone isoenzyme of alkaline phosphatase. 138 27

Twenty postmenopausal women (aged between 46 and 67 years old) with skeletal metastases from breast carcinoma were treated with clodronate 450 mg i.v. daily for 5 days and thereafter with 100 mg i.m. daily for 10 days. All patients received standard hormonal therapy (tamoxifen). Symptomatic pain (evaluated according to a linear analog scale), performance status (according to Karnofsky), serum alkaline phosphatase, serum creatinine and osteocalcin were measured before and after treatment on days 5, 15, 30 and 45. Scanning by radiology were performed pre- and post-therapy. Bone pain was significantly reduced in 15 out of 20 patients. After clodronate treatment the base line value of circulating osteocalcin (3.2 +/- 1.6 ng/ml) showed a significant increase on days 30 and 45 (p less than 0.001). Radiological assessment of bone lesions showed stable disease in 18 patients and progression in two patients. No adverse side effects were observed. These data show that clodronate provided pain relief in 75% of treated patients and the increase in circulating osteocalcin levels can be considered a marker of the stabilization of skeletal metastatic lesions.
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PMID:Subjective and metabolic effects of clodronate in patients with advanced breast cancer and symptomatic bone metastases. 138 63

Thirty-five women with symptomatic fibroids were treated with monthly injections of 3.2 mg microcapsulated D-Trp-6-LHRH for 6 months. During treatment serum 17 beta-oestradiol levels decreased, falling to castration levels associated with a reduction in the volume of the fibroids. In 16 patients a complete calcium homeostasis and bone metabolism work-up was carried out during treatment and subsequently for a 6-month follow-up period. Bone mineral content (BMC) and Compton bone densitometry readings remained unchanged. There were significant increases in serum calcium phosphate and alkaline phosphatase concentrations. A slight although not significant increase was observed in osteocalcin and parathyroid hormone (PTH) serum levels. Serum 1,25(OH)2D3 values decreased significantly after 3 months of treatment. Urinary hydroxyproline/creatinine and calcium/creatinine ratios as well as 24-h urinary calcium values increased significantly during the treatment period but decreased rapidly to pretreatment values after 3 months in the follow-up period. The endocrine changes induced by the GnRH-agonist treatment were associated with reversible biochemical signs of increased bone turnover and no significant changes in bone mass, suggesting that the treatment can be administered safely for a period of 6 months in patients with oestrogen-dependent diseases.
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PMID:Calcium homeostasis, bone metabolism and safety aspects during long-term treatment with a GnRH agonist. 138 19

A predictable animal model with skeletal remodeling characteristics similar to those of humans is needed to facilitate the understanding of the mechanism of postmenopausal osteoporosis. We have utilized the ovariohysterectomized (Ovh) dog to examine cellular and biochemical responses to estrogen depletion and PTH stimulation. Histomorphometric measurements of bone biopsies taken prior to (first biopsy) and five months after the operation (second biopsy) showed no significant differences in static and dynamic parameters. Bone mineral density of the excised vertebrae displayed the same values between the two groups six months after surgery. Between the second biopsy and sacrifice, two infusion studies were performed. A two-hour infusion of EDTA followed by a two-hour recovery period elicited a rapid response in PTH production, highly correlated to the changes in ionized calcium, but no significant difference in response was observed between Sham and Ovh groups. A short-term (24-h) infusion of 1-34 hPTH increased circulating ionized calcium and 1,25-(OH)2-D levels to a similar extent in both groups. The levels of alkaline phosphatase were constant and both groups showed a small but nonsignificant increase in osteocalcin. The lack of sizable responses in histomorphometric, bone mass, and biochemical parameters may limit the utility of dogs for the study of cancellous bone loss in ovarian-dysfunction osteoporosis.
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PMID:Lack of changes in histomorphometric, bone mass, and biochemical parameters in ovariohysterectomized dogs. 138 70

Thirty-six women with postmenopausal osteoporosis (31 of them with at least one non-traumatic vertebral compression fracture) were matched pair-wise as to age, years since menopause and body mass index and randomized to receive either cyclical estrogen-progestagen replacement treatment (group 1) or the same treatment plus nandrolone decanoate (group 2). During the first year of treatment in both groups the forearm BMC (SPA) rose proximally and distally 2-3%. Over 2 years the increments of forearm BMC in both groups were up to 4.5%. Lumbar BMC (DPA) rose in both groups nearly 10% over the first year and 12-12.5% over 2 years. The cancellous bone density of L3 (QCT) showed in 6 months an increase of 21% in group 1 and 29% in group 2 to subsequently stay at that level. All these changes from the basal levels were highly significant but there were no significant differences between the two groups. These two conclusions were also drawn with regard to the induced fall of serum alkaline phosphatase (-23%), osteocalcin (-35% to -44%) and procollagen I (-15% to -22%) and of the fasting urinary hydroxyproline (-33% to -36%). No significant increase in the number of newly deformed vertebrae occurred in 2 years.
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PMID:Can nandrolone add to the effect of hormonal replacement therapy in postmenopausal osteoporosis? 139 98


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