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)

Both 1,25-(OH)2D3 and prostaglandin E2 (PGE2) stimulate alkaline phosphatase activity in MC-3T3-E1 cells. Previous studies, demonstrating a correlation between 1,25-(OH)2D3-dependent alkaline phosphatase and phospholipase A2 activities in matrix vesicles isolated from growth cartilage chondrocyte cultures, suggest that one mechanism of vitamin D action may be via autocrine or paracrine action of PGE2. Since most PGE2 is derived from arachidonic acid released by the action of phospholipase A2, we examined whether 1,25-(OH)2D3 stimulates phospholipase A2 activity in three osteoblastic cell lines: ROS 17/2.8 cells, MC-3T3-E1 cells, and MG-63 cells. 1,25-(OH)2D3-dependent alkaline phosphatase and phospholipase A2 activity were correlated with production of PGE2 and PGE1 in the MC-3T3-E1 cells. Alkaline phosphatase specific activity was enriched in the matrix vesicles produced by all three cell types and was stimulated by 1,25-(OH)2D3 at 10(-8) to 10(-7) M. Although phospholipase A2 specific activity was enriched in the matrix vesicles produced only by the ROS 17/2.8 cell cultures, stimulation of this enzyme activity was observed only in the MC-3T3-E1 cell cultures. The effects of 1,25-(OH)2D3 on phospholipase A2 were dose-dependent and were significant at 10(-8) to 10(-7) M. There was a significant increase in PGE2 production in the MC-3T3-E1 cell cultures only. Indomethacin reduced PGE2 production to base line values. Even at baseline, MC-3T3-E1 cells produced ten times more PGE2 than did the ROS 17/2.8 or MG-63 cell cultures. The effects of 1,25-(OH)2D3 on PGE1 were comparable to those on PGE2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential regulation of prostaglandin E2 synthesis and phospholipase A2 activity by 1,25-(OH)2D3 in three osteoblast-like cell lines (MC-3T3-E1, ROS 17/2.8, and MG-63). 158 Nov 9

Bone at the tissue level undergoes remodeling: it is continuously being resorbed and rebuilt (or formed). A negative balance between bone resorption and formation, frequently due to excessive resorption, is the basis of many bone diseases. Resorption is carried out by osteoclasts, which are specialized multinucleated cells of hemopoietic origin. Bone resorption takes place at a specialized area of the osteoclast cell membrane called "ruffled border," which comprises a sealed lysosomal compartment where the acidic pH solubilizes the mineral and the proteolytic enzymes digest the matrix. Among the agents that inhibit bone resorption, only calcitonin and bisphosphonate have been shown to act directly on osteoclasts. Other hormones and agents, which modulate bone turnover, probably act on the osteoblasts or cells of the osteoblast lineage. Osteoblasts are bone-forming cells, originating from cells resident in bone committed to the osteoblastic lineage. They synthesize and secrete most of the proteins of the bone matrix, including type I collagen and noncollagenous proteins. They possess high levels of alkaline phosphatase, which participates in mineralization. Proteins, produced by osteoblasts, spill over into the blood and are used as indicators of bone formation. In addition to the matrix-forming ability, cells of the osteoblastic family (osteocytes, lining cells, and maybe other cells) participate in the regulation of bone turnover. They respond to parathyroid hormone, glucocorticoids, vitamin D, sex steroids, insulin, prostaglandins, growth factors, and so on. There are a significant number of cytokines, that are locally produced and may control bone resorption. These include prostaglandins, IL1, TNF alpha, possibily IL6.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Introduction to bone biology. 158 Nov 17

Since it has been suggested that gastric resections are followed by changes in bone metabolism, the aim of our study was to determine the biochemical parameters of bone metabolism and radial and lumbar bone density in 15 male ulcus patients treated by partial gastrectomy (Billroth II). Comparing the data with those of a corresponding control group, the lumbar bone density measured by quantitative computed tomography was statistically significantly lower (P less than 0.04) in the patient group, whereas the peripheral bone mass of the distal part of the nondominant forearm measured by single-photon absorptiometry showed no statistically significant difference. In addition, a marked increase in alkaline phosphatase (P less than 0.002) and urinary excretion of hydroxyproline (P less than 0.003) was found in gastrectomy group, whereas the 25-hydroxy-vitamin D levels were found to be significantly decreased (P less than 0.04). Osteocalcin, a biochemical marker for osteoblast activity, and the carboxy-terminal propeptide of type I procollagen (PICP), a marker of collagen formation, were slightly but not significantly higher in gastrectomy-treated patients. The serum parathyroid hormone levels were similar in both groups. As none of the patients had any radiologic evidence of osteopenia, the changes in biochemical parameters of bone metabolism and bone mass in patients who had undergone partial gastrectomy could be a marker of latent bone loss.
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PMID:The influence of partial gastrectomy on biochemical parameters of bone metabolism and bone density. 160 Mar 54

Thirty seven postmenopausal women aged under 65 with densitometric osteoporosis defined by a bone density value below the 80th percentile of the osteoporotic population but without identifiable crush fractures, were treated and monitored for two years using clinical, laboratory and densitometric parameters. Sixteen of them were given hormonal replacement therapy combining percutaneous or transdermal 17 beta estradiol with a progestogen and the other 21 sodium fluoride at the dose of 50 mg/d combined with calcium and vitamin D. There was a significant increase in vertebral bone density in both groups: 6.3 +/- 0.9 per cent for hormone treatment and 7.1 +/- 1.5% for fluoride after 2 years, while it fell in a control group. The increase was linear with fluoride, while 2/3 of the gain was acquired by the end of the first year of hormonal therapy. Nine of the 16 patients on hormonal therapy and 9 of the 21 taking fluoride showed a significant vertebral gain at 2 years (greater than or equal to 0.043 g/cm2). There was no parameter which enabled the identification of "responders" before treatment. There was no difference in changes in femoral bone density between patients treated with fluoride and controls. From a laboratory standpoint, hormonal therapy caused a significant fall at 12 months in the urinary calcium/urinary creatinine ratio, and a non-significant fall in osteocalcin at 2 years. With fluoride, there was a marked rise in osteocalcin and a more moderate rise in alkaline phosphatase, reflecting stimulation of bone formation without any variation in resorption. In conclusion, this study shows the ability of both these types of treatment of increasing, by different mechanisms, the vertebral bone density of osteoporotic women. However, it does not indicate the extent to which this gain in bone density might have a positive influence on fracture risk.
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PMID:[Comparative effects of sodium fluoride and hormonal replacement therapy on bone metabolism in osteoporotic women with high fracture risk. Results of monitoring for 2 years]. 160 21

Matrix vesicles are extracellular organelles produced with distinctive phospholipid composition and enzyme activity. They are produced by cells which typically calcify their extracellular matrix and their characteristics are cell-maturation dependent. Regulation of matrix vesicle structure and function occurs at the genomic and non-genomic levels. By following alkaline phosphatase gene transcription, protein concentration, and enzyme specific activity, we have shown that steroid hormones and growth factors exhibit a regulatory influence over gene transcription, protein synthesis, and matrix vesicle activity. Matrix vesicles respond to peptide hormones, other matrix proteins, like alpha 2-HS-glycoprotein, and autocoid mediators as well. Matrix vesicle metabolism can be directly affected by vitamin D metabolites, even in the absence of cells. The results indicate that 1,25-(OH)2D3(1,25D) or 24,25-(OH)2D3(24,25D) produced by the cells in culture can modulate matrix vesicle activity, and suggest that calcifying cells can modulate events in the matrix via autocrine/paracrine stimulation or inhibition of the matrix vesicles. 1,25D and 24,25D regulate matrix vesicle phospholipase A2 activity, fatty acid turnover, arachidonic acid release, PGE2 production and membrane fluidity, which act on the matrix vesicle to alter enzyme activity. Since vitamin D metabolite production is sensitive to both hormones and growth factors, there is potential for fine tuning matrix vesicle behavior.
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PMID:Cell maturation-specific autocrine/paracrine regulation of matrix vesicles. 161 18

The effect of beta-alanyl-L-histidinato zinc (AHZ) on bone metabolism in the femoral diaphysis of rats fed on low-calcium and vitamin D-deficient diets was investigated. Rats were orally administered AHZ (10, 30, and 100 mg/kg per day) for 14 days and were killed on the 15th day. Feeding with low-calcium and vitamin D-deficient diets caused a significant decrease in serum 25-hydroxy-vitamin D3, calcium, and inorganic phosphorus concentrations. These decreases were not prevented by AHZ administration. Meanwhile, the femoral-diaphyseal calcium and phosphorus contents were significantly reduced by feeding with the deficient diets. Decrease in bone calcium content was significantly prevented by the doses of 30 and 100 mg AHZ/kg. Furthermore, the dose of 100 mg AHZ/kg produced a significant increase in bone deoxyribonucleic acid (DNA) content and alkaline phosphatase activity in rats fed on the deficient diets. Bone zinc content in the deficient rats was significantly increased by the doses of AHZ (30 and 100 mg/kg). The present results suggest that oral administration of AHZ has a preventive effect in the development of deteriorating bone metabolism in rats fed on low-calcium and vitamin D-deficient diets.
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PMID:Preventive effect of beta-alanyl-L-histidinato zinc on bone metabolism in rats fed on low-calcium and vitamin D-deficient diets. 163 66

To study the effect of a large dose of 24R,25(OH)2D3 on bone metabolism, we treated vitamin D-replete rabbits with the agent for eight weeks. Fifteen rabbits 20 weeks of age were divided into three groups of five animals each. Group I received only the vehicle; groups II and III were given the agent at doses of 10 micrograms/kg/d, and 100 micrograms/kg/d, respectively. Through the dosing period, serum calcium, phosphorus, alkaline phosphatase, and creatinine levels were not altered. By the end of the experiment, serum 1,25(OH)2D or serum 25(OH)D levels did not change, nor did the PTH level. Serum 24,25(OH)2D levels for groups I, II, and III were 5.25 +/- 3.40, 76.16 +/- 19.90 (p less than .01), and 199.0 +/- 30.90 (p less than .01) ng/ml, respectively. The bone mineral content (BMC) significantly increased in group III. The percentages of BMC increase in group III over group I were 14.5% on the femur, 34.1% (p less than .01) on the sixth lumbar vertebra, and 23.3% (p less than .05) on the seventh lumbar vertebra. A marked increase of bone mineral densities in the cancellous bone-rich regions was seen in group III. Bone histomorphometry on the seventh lumbar vertebra demonstrated that both the eroded surface and the osteoclast number were reduced and the surfaces indicating bone formation such as the osteoid surface and the tetracycline double labeled surface were also reduced. However, both the osteoid thickness and the mineral apposition rate increased and the mineral formation rate at the tissue level remained approximately equal to that in the control.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Increased bone volume and reduced bone turnover in vitamin D-replete rabbits by the administration of 24R,25-dihydroxyvitamin D3. 163 69

In a group of 88 patients, immobile for various reasons a markedly reduced bone mineralization was found, significantly more in patients with denervation of the muscles. As to laboratory indicators, the author recorded a significantly reduced serum calcium level which correlated positively with the mineralization level; there was an insignificantly elevated alkaline phosphatase activity and calciuria. After comprehensive calcium treatment with small doses of vitamin D, and in patients without signs of osteomalacia also with sodium fluoride raised also significantly the serum calcium level, while there was a decline of the alkaline phosphatase activity and a slight increase of calciuria. The fundamental requirement of therapy is burdening of the bones by graded mobilization of the patients. The following series proved useful: isometric contraction of muscles in a recumbent position--standing up, assisted next to the bed--moving round the bed--active rehabilitation.
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PMID:[The effect of inactivity on bone mineralization]. 163 93

We report a 3-year analysis (1986 to 1989) of the management of 63 home parenteral nutrition patients, 40 with short-bowel syndrome and 23 with chronic intestinal obstruction with or without intestinal resection. Intravenous fluid requirements varied from 0.9 to 6 L/day, and the content of glucose varied between 46 and 531 g/day, protein varied from .0 to 85 g/day, fat from .0 to 100 g/day, sodium from 37 to 695 mEq/day, potassium from 30 to 220 mEq/day, chloride from 60 to 760 mEq/day, and acetate from 0 to 200 mEq/day. Body weight was normalized and well maintained in the majority of patients, but using the strict definition of deficiency as the presence of one abnormal value during 3 years, more than half had abnormal plasma chloride, glucose, alkaline phosphatase, serum glutamic oxaloacetic transaminase, total protein, albumin, selenium, and iron concentrations, and more than a third had low calcium, magnesium, vitamin D, and vitamin C levels. Normochromic anemia was seen in 73% and high blood creatinine associated with low urine volumes in 42%. Most (78%) returned to relatively normal lifestyles, but employability was occasionally impaired by loss of third-party insurance coverage resulting from a therapy that may cost $100,000 per year. Overall mortality was low (5% per year), but 73% needed readmission to hospital, mainly for suspected catheter sepsis. The results indicate that home parenteral nutrition has allowed many patients to survive gut failure and return to work but problems with chronic fluid, electrolyte and micronutrient deficiencies, catheter sepsis, and insurance coverage often restrict optimal rehabilitation.
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PMID:Home parenteral nutrition--a 3-year analysis of clinical and laboratory monitoring. 850 44

22-Oxacalcitriol (OCT), a synthetic vitamin D analog, can mimic the ability of 1,25-dihydroxyvitamin D3[1,25-(OH)2D3] to differentiate leukemia and skin cells, to enhance the immune response and to suppress PTH secretion, but has much less calcemic activity. The mechanism for this selective action is not understood. OCT has been shown to have a diminished ability to mobilize calcium from bone in vivo, but in vitro findings are contradictory. Little is known about the effect of OCT on bone forming cells. Therefore, the present studies were designed to investigate the actions of OCT at the molecular level in the osteoblast-like cell line, ROS 17/2.8. 3H-OCT was bound to the vitamin D receptor (VDR) in intact cells at the same rate as 3H-1,25-(OH)2D3. As previously found for 1,25-(OH)2D3, the time course of specific binding of OCT was biphasic, with an initial plateau at 1 h and a further increase from 2-8 h. Scatchard analysis demonstrated that exposure to 3H-1,25-(OH)2D3 increased VDR from 24 fmol/mg protein at 2 h to 85 fmol/mg protein at 8 h. Exposure to 3H-OCT increased VDR from 22 to 76 fmol/mg protein, indicating that OCT is also capable of up-regulating the VDR in ROS 17/2.8 cells. In contrast to the lower affinity of OCT for VDR reported for chick intestine and HL-60 cells, the Kd for OCT in intact ROS 17/2.8 cells was identical to that for 1,25-(OH)2D3. The effect of OCT on osteocalcin secretion and alkaline phosphatase (ALP) activity in ROS 17/2.8 cells was also determined. Pretreatment for 24 h with either 1,25-(OH)2D3 or OCT resulted in a dose-dependent enhancement of osteocalcin secretion. A 2-fold stimulation by both compounds was observed with 10(-7)M. ALP activity was measured after a 72-h incubation with 10(-7)M 1,25-(OH)2D3 or OCT. Both compounds increased ALP activity to the same extent. Stimulation by OCT of VDR levels, ALP activity, and osteocalcin secretion were inhibited by the addition of 5 microM cycloheximide, indicating that these actions of OCT require new protein synthesis. Thus, OCT, like 1,25-(OH)2D3, up-regulates the vitamin D receptor, stimulates osteocalcin secretion, and increases ALP activity in ROS 17/2.8 cells, suggesting that the analog may be as active as 1,25-(OH)2D3 in stimulating bone formation in vivo. The low activity of OCT in mobilizing calcium from bone in vivo does not appear to be due to an inability of this compound to act on osteoblasts.
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PMID:The activity of 22-oxacalcitriol in osteoblast-like (ROS 17/2.8) cells. 164 45


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