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

---

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

The effect of sodium fluoride on alkaline phosphatase (ALP) release and [3H]thymidine uptake by human osteoblasts in culture was investigated. Sodium fluoride stimulated both ALP release and [3H]thymidine uptake at concentrations of sodium fluoride greater than 250 mumol/L. This stimulation was similar in magnitude to that induced by 1,25-dihydroxycholecalciferol. The fluoride-induced increase in ALP was inhibited by verapamil, a calcium channel blocker. We conclude that sodium fluoride stimulates osteoblasts to proliferate and to release ALP. This stimulation by fluoride is dependent on calcium influx. Fluoride-induced stimulation of human osteoblasts may be relevant to its effect in enhancing bone formation in patients with osteoporosis.
...
PMID:Fluoride stimulates [3H]thymidine incorporation and alkaline phosphatase production by human osteoblasts. 223 70

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) greatly enhances sodium butyrate (NaB)-induced enterocyte differentiation of HT-29 human colonic carcinoma cells while 1,25-(OH)2D3 alone induces growth restriction without associated differentiation. In the present study, the efficacies of various analogs of 1,25-(OH)2D3 to enhance NaB-induced HT-29 differentiation and to prolong the reversal of the differentiated phenotype under NaB-free growth conditions were subsequently examined. Extent of HT-29 differentiation was assessed by measurement of alkaline phosphatase (AP) activity, appearance of mucin-producing cells, changes in morphological characteristics, and expression of differentiation-associated cytokeratin proteins. Among active analogs of 1,25-(OH)2D3, 26,26,26,27,27,27-hexafluoro-1,25-(OH)2D3 (F6-1,25-(OH)2D3), 24,24-difluoro-24-homo-1,25-(OH)2D3, and 26,27-dimethyl-1,25-(OH)2D3 were 100-, 10-, and 5-fold, respectively, more effective than 1,25-(OH)2D3 in enhancing NaB-induced mucin production. Combined use of NaB and F6-1,25-(OH)2D3 (10(-9) M) also induced HT-29 cells to form highly differentiated goblet-like enterocytes, and increased both cellular AP enzymatic activity and tissue-type cytokeratin content. This differentiated state was qualitatively more advanced than that achieved by a combination of NaB and 10(-7) M 1,25-(OH)2D3. NaB-mediated HT-29 differentiation (in short-term inductions) was found to be reversible following a return to NaB-free medium. HT-29 cells differentiated by combined use of NaB and 1,25-(OH)2D3 or its analogs exhibited a significant prolonged reversal time relative to cells differentiated with NaB alone. The most prominent effect was achieved using cells differentiated with NaB and 10(-9) M F6-1,25-(OH)2D3 which exhibited a 7-fold prolonged reversal time over colonocytes differentiated by NaB alone. Our data suggest that a combined use of NaB and 1,25-(OH)2D3 or its derivatives may provide a convenient in vitro model system to probe molecular events associated with steroid-target tissue interactions in a differentiating cell system as commonly occurs in vivo. Such an analysis might lend itself to design of a rational combination differentiation-based therapy for the clinical management of colon cancer.
...
PMID:Effects of 1,25-dihydroxyvitamin D3 and its analogs on butyrate-induced differentiation of HT-29 human colonic carcinoma cells and on the reversal of the differentiated phenotype. 230 5

Acro-osteolysis with diffuse osteoporosis in the absence of other associated diseases is named Hajdu-Cheney syndrome. Reduced bone formation rather than enhanced bone resorption has been indicated as the mechanism of osteoporosis. On the assumption that in this syndrome the active bone resorption which produces distal osteolysis must also predominate in generalized osteoporosis, we investigated bone histology, calcium kinetics, calciotropic hormones and bone markers in a patient suffering from sporadic Hajdu-Cheney syndrome. A radius bone biopsy taken far from the osteolytic lesions showed severe osteoporosis with a marked increase in osteoclastic bone resorption and reduced bone formation. Total body calcium clearance, performed through an analysis of the kinetics of calcium infusion, was 2.8 times higher than in normal controls, indicating the presence of active osteoclastic bone resorption. Serum parathormone, 1,25-dihydroxycholecalciferol, alkaline phosphatase and urinary hydroxiproline were in the normal range. These data indicate that in Hajdu-Cheney syndrome trabecular osteoporosis is produced by the same mechanism that induces distal osteolysis, which suggests that it may be sustained by local acting factors stimulating osteoclastic resorption.
...
PMID:High turnover osteoporosis in acro-osteolysis (Hajdu-Cheney syndrome). 236 59

The effects of vitamin D metabolites on alkaline phosphatase [ALPase; orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] activity, a marker of terminal differentiation, in chondrocyte cultures and growth plates in vivo were examined. In cultures of pelleted rabbit growth-plate chondrocytes, 1,25-dihydroxycholecalciferol (1,25-dihydroxyvitamin D3) increased the contents of DNA and macromolecules containing uronic acid (proteoglycans). It also decreased ALPase activity with an ED50 of less than 1 nM. Other vitamin D3 metabolites, such as 24,25-dihydroxycholecalciferol and 25-hydroxycholecalciferol, had little effect on these biochemical parameters. In rachitic growth plates, the uronic acid content was half that in normal growth plates, whereas ALPase activity was 2.5 times that in normal growth plates. Administration of 1,25-dihydroxycholecalciferol at a low dose (0.1 micrograms per kg of body weight) to rachitic rats increased the uronic acid content 1.4-fold and decreased ALPase activity by 40%. This compound, like 24,25-dihydroxycholecalciferol (10 micrograms per kg of body weight), increased the calcium level of the blood. However, administration of 24,25-dihydroxycholecalciferol had little effect on the uronic acid and ALPase contents in growth plates. These observations suggest that 1,25-dihydroxycholecalciferol is a bioactive form of vitamin D that plays an important role in the control of chondrocyte terminal differentiation.
...
PMID:Role of 1,25-dihydroxycholecalciferol in growth-plate cartilage: inhibition of terminal differentiation of chondrocytes in vitro and in vivo. 239 58

Cartilage calcification at specific sites is a key event that leads to skeletal development and growth. To obtain insights into the control of cartilage calcification, we examined whether cells distributed in permanent cartilage regions might have the ability to express the calcification-related phenotype in a permissive environment. Chondrocytes were isolated from the permanent and growth plate cartilages of 4-week-old rabbit ribs. They were seeded as a pelleted mass in a centrifuge tube and cultured in Eagle's minimum essential medium supplemented with 10% fetal bovine serum. These cells proliferated for several generations, and then synthesized large amounts of proteoglycans, yielding a cartilage-like tissue in 16 days. Cultures from the permanent and growth plate cartilages showed similar time courses for increases in DNA synthesis and proteoglycan production that reached similar maximal levels. Thereafter, they initiated the syntheses of alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor and induced matrix calcification without additional phosphate. The increases in alkaline phosphatase, 1,25-dihydroxycholecalciferol receptor, and calcium contents in cultures from the permanent cartilage were consistently delayed for 4-7 days relative to the growth plate-derived cells, but caught up by Day 28. The maximal levels of alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor in the cultures from the permanent cartilage were 40- to 100-fold higher than that of the in vivo permanent cartilage. These results provide evidence that permanent cartilage cells in postnatal young rabbit ribs have the capacity to express alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor and induce calcification in a permissive environment, although they never express these calcification-related phenotypes in vivo.
...
PMID:Hypertrophy and calcification of rabbit permanent chondrocytes in pelleted cultures: synthesis of alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor. 255 37

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) significantly stimulated cellular alkaline phosphatase activity in a human osteoblastic osteosarcoma cell line (TE-85 cells) in serum-free medium with 0.1% bovine serum albumin as the hormone carrier in a dose- and a time-dependent manner. The extent of the maximal stimulation was greater and the minimal dose that was required for stimulation was lower than those previously reported for TE-85 cells in the presence of serum. The magnitude of the stimulation of alkaline phosphatase activity by 1,25(OH)2D3 varied with the cell density. Daily changes of conditioned medium, as compared with no medium changes, significantly reduced the magnitude of the stimulation, suggesting that endogenous factors secreted into culture medium could play an enhancing role. Finally, application of Northern blot analysis using an oligodeoxynucleotide probe corresponding to a unique sequence of the human bone/liver/kidney alkaline phosphatase cDNA coding region revealed that 1,25(OH)2D3 increased the alkaline phosphatase mRNA level, suggesting that the increase in alkaline phosphatase activity was a result of either an increase in the rate of transcription or an increase in message stability.
...
PMID:Stimulation of cellular alkaline phosphatase activity and its messenger RNA level in a human osteosarcoma cell line by 1,25-dihydroxyvitamin D3. 259 47

Different therapeutic regimens have been proposed by Authors in the treatment of involutional (and particularly postmenopausal) osteoporosis. Following the up to date concepts on bone remodelling, an ADFR (Activate, Depress, Free, Repeat) trial was performed in 20 females affected by involutional osteoporosis. They were treated with Calcitriol 2 mcg/d for 7 days, followed by a 21 days period of 100 U/d Salmon Calcitonin + 1 g/d Calcitonin, followed by a 2-month period of Calcium alone. The cycles were repeated for 1 year and the results of densitometric examinations (radial mineral content evaluated by single photon absorptiometer, and vertebral mineral content evaluated by dual photon absorptiometer) and of biochemical markers (Ca++, P, osteocalcin, alkaline phosphatase, hydroxyproline) controlled every 3 months, were compared with those obtained in a group of patients treated only with Salmon Calcitonin and in a group treated with Calcium for 1 year. After two therapeutical cycles radial bone mineral density significantly increased; vertebral bone density also increased but not significantly. The effects were more evident in comparison to calcitonin alone treatment. A significant reduction in serum osteocalcin was documented. At the end of the therapy no further improvement was registered. This suggests that some variations and adaptation of therapeutic strategy are needed to achieve a more important and substantial improvement of bone conditions.
...
PMID:[Sequential calcitriol-calcitonin in the therapy of osteoporosis]. 265 53

The value of calcitriol administration in the management and prevention of renal bone disease was studied in a prospective double-blind manner in 16 patients with chronic renal impairment (creatinine clearance 20 to 59 ml per min). They were given either calcitriol at a dose of 0.25 to 0.5 micrograms daily (eight patients), or placebo. Transiliac crest bone biopsies were performed before entrance into the study and after 12 months of experimental observation. None of the patients were symptomatic or had biochemical or radiological evidence of bone disease. Of the thirteen patients who completed the study, initial serum 1,25(OH)2D levels were low in seven patients and parathyroid hormone levels were elevated in seven patients. Bone histology was abnormal in all patients. Calcitriol treatment was associated with a significant fall in serum phosphorus concentrations and alkaline phosphatase levels as well as with histological evidence of an amelioration of hyperparathyroid changes. In contrast to previous reports, no deterioration of renal function attributable to the treatment occurred, perhaps because a modest dose of calcitriol was employed combined with meticulous monitoring. Further investigation is required to determine whether alternative therapeutic strategies (smaller doses or intermittent therapy) may avoid the potential for suppressing bone turnover to abnormally low levels in the long term.
...
PMID:Early therapy of renal bone disease with calcitriol: a prospective double-blind study. 269 94

Hexachlorobenzene (HCB) exposure has been shown to alter the normal concentrations of parathyroid hormone and 1,25-dihydroxyvitamin D3 in rats and to result in osteoporosis in humans. Experiments were undertaken to investigate the effects of HCB on the homeostatic mechanism of calcium metabolism and to determine its effect on bone in rats. Fischer 344 rats were dosed 5 days/week for 5, 10, or 15 weeks with 0, 0.1, 10.0, or 25.0 mg HCB/kg body wt. Body weight was not affected by any of the exposure conditions. Liver weight was significantly elevated above control values at the two higher dose levels at all three time periods. Kidney weight and kidney-to-body weight ratio were significantly elevated at the highest dose level after 10 weeks and at the two higher dose levels after 15 weeks of exposure. Serum alkaline phosphatase was significantly decreased at the two higher dose levels after both 10 and 15 weeks of exposure. 1,25-Dihydroxyvitamin D3 was measured in the 5-week exposure group only and was significantly elevated in the three higher dose levels. After 5 and 15 weeks of HCB exposure, parathyroid hormone concentration was significantly elevated at the two higher dose levels at both time periods. Wet femur density was significantly increased at the two higher dose levels of HCB after 10 weeks of exposure and the three higher dose levels after 15 weeks of exposure. Dry femur density was also increased in the cases where wet femur density was increased. However, femur weight was not affected at any dose level. The results from this study indicate that HCB induces hyperparathyroidism in rats, as demonstrated by increased serum parathyroid hormone levels and osteosclerosis of the femur.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Hexachlorobenzene-induced hyperparathyroidism and osteosclerosis in rats. 271 25

Clinical investigations have shown that 1 alpha-hydroxycholecalciferol (oxydevit, alphacalcidiol) and 1 alpha, 25-dihydroxycholecalciferol (rocaltrol) are act vitamin D3 agents producing a positive clinical effect in different types of osteoporosis and osteomalacia. Clinical improvement of the patients' status (alleviation of the pain syndrome, an increase in motor activity) was noted in 1-2 mos., an x-ray picture of regeneration of the bone structure of both axial and peripheral skeleton--in 6-12 mos. after the initiation of therapy. Therapy was attended by an increase in the serum content of total and ionized calcium, the return of alkaline phosphatase activity to normal, and a decrease in the level of parathormone. During prolonged therapy these agents administered at daily doses of 0.25-2 micrograms caused no pathological side-effects and hypercalcemia. In osteoporotic conditions all these drugs were equal in their clinical effectiveness. Rocaltrol has some advantages in the presence of associated liver pathology.
...
PMID:[Comparative evaluation of the effectiveness of vitamin D3 preparations (1-alpha-hydroxy- and 1-alpha,25-dihydroxycholecalciferol in various forms of osteoporosis and osteomalacia]. 276 60


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---