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)

The effect of citrinin poisoning on rabbit kidney alkaline phosphatase was investigated. After seven days administration of citrinin (2 mg/kg body weight daily) the animals were sacrificed and the level of enzymes estimated in serum and kidney. Serum enzymes showed no variation in activity in the citrinin-treated animals, but in kidney, alkaline phosphatase activity decreased significantly. The decreased activity was mainly associated with the cytoplasmic fraction and in fractions Ib and II. The enzyme II obtained from citrinin-treated animal showed no kinetic difference in substrate specificity, inhibition by phenylalanine, phosphate, sodium-EDTA and Zn2+ ions, activation by Mg2+ ions, thermal inactivation and electrophoretic mobility to that of control Enzyme II. Immunological studies showed that the decrease in enzyme activity was due to existence of inactive enzyme protein. Hormones like cyclic AMP, prostaglandin E1 and parathyroid hormone reversed the decreased enzyme activity due to citrinin poisoning in mouse and rabbit. This study favours the possible existence of active and inactive forms of alkaline phosphatase in the system.
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PMID:The mechanism of action of citrinin on rabbit kidney alkaline phosphatase activity in vivo. 19 68

Pinealectomy leads to increased formation of fibrous tissue in the abdominal cavity, increased skin pigmentation and elevated cholesterol and alkaline phosphatase levels. It also leads to reduced formation and/or action of prostaglandin (PG) E1 and thromboxane (TX) A2. PGE1 plays an important role in enhancing function of T suppressor lymphocytes which control overactive antibody-producing B lymphocytes. In primary biliary cirrhosis there are increased skin pigmentation, hepatic fibrosis, elevated cholesterol and alkaline phosphatase levels, defective T lymphocytes and hyperactive B lymphocytes. Primary biliary cirrhosis may be a pineal deficiency disease. Serotonin is important in the pineal and the serotonin antagonist methysergide may cause retroperitoneal fibrosis by interfering with pineal function. There is a good deal of other evidence which suggests that melatonin PGE1 and TXA2 are important in the regulation of fibrosis in other situations such as "collagen" diseases, lithium-induced fibrosis and cardiomyopathies. This suggests that enhancement of formation of PGE1 and TXA2 may be of value in diseases associated with excess fibrosis and defective T suppressor cell function. PGE1 levels may be raised by zinc, penicillin, penicillamine and essential fatty acids. TXA2 levels may be raised by low dose colchicine. These new approaches to treatment may prove safer and more effective than existing ones. They may be of value in disorders such as cardiomyopathy, Hodgkin's disease and other lymphomas, multiple sclerosis, Crohn's disease, atopy and other diseases in which defective T cell function is suspected.
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PMID:The pineal and regulation of fibrosis: pinealectomy as a model of primary biliary cirrhosis: roles of melatonin and prostaglandins in fibrosis and regulation of T lymphocytes. 31

The relationship between the concentration of cAMP-dependent protein kinase (PKA) activity and the induction of alkaline phosphatase (AP) was examined in transfected L cell lines with altered PKA levels. C alpha 12 cells were generated by transfecting mouse L cells with an expression vector coding for the mouse C alpha catalytic subunit of PKA and were shown to contain 2.5-fold more PKA activity than L cells. RAB10 cells were generated by transfection with an expression vector for a mutant regulatory subunit and had 10-fold lower levels of PKA activity than L cells. AP induction by 8-chlorophenylthio-cAMP (CPT-cAMP) was found to be 2-fold greater in C alpha 12 cells than in L cells, while RAB10 cells lacked any induction of AP in response to CPT-cAMP. Northern blot and solution hybridization analyses of AP mRNA showed that induced AP mRNA levels were comparable in C alpha 12 and in L cells. Western blot analysis demonstrated that AP protein levels were greater in C alpha 12 cells and suggested that the increased AP protein level resulted from either increased stability of the AP protein or increased rate of translation of the AP mRNA. In contrast, Northern blot analysis of the RAB10 cells failed to detect AP mRNA after CPT-cAMP treatment and suggested that PKA is required for induction of AP mRNA. Stimulation of endogenous cAMP levels by treatment with prostaglandin E1 gave similar effects on AP activity as those seen with CPT-cAMP. These results indicate that cellular levels of PKA can determine the magnitude of cellular response to hormonal stimulation and also suggest that PKA can regulate AP gene expression at both the level of the AP mRNA and AP protein.
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PMID:Cellular concentrations of protein kinase A modulate prostaglandin and cAMP induction of alkaline phosphatase. 131 34

The addition of insulin plus transferrin to Leibovitz's L-15 medium was previously shown to restore important cellular functions in a serum-free system developed in our laboratory for human fetal kidney explants. The objective of the present study was to compare the effectiveness of this insulin plus transferrin combination with one used in other in vitro systems whereby serum is substituted by a mixture of five hormones (insulin, transferrin, hydrocortisone, triiodothyronine and prostaglandin E1). In fetal kidney it was found that the combination of insulin plus transferrin was as effective as the five-hormone mixture on DNA synthesis after 5 days of culture and was even more effective in younger fetuses (10-13 weeks) compared with older fetuses (16-19 weeks). However, protein synthesis was more sensitive to the five-hormone combination. Selective deletion of individual hormones showed that insulin is the essential factor for the growth of cultured kidney explants. Differentiation of brush border membranes in nephrons, as evaluated by alkaline phosphatase and gamma-glutamyl-transferase activities, was not significantly modified by either of the two combinations. The present results indicate that insulin plus transferrin represents the optimizing condition for our culture model. The response to supplements varies according to fetal age and possibly to tissue proliferation states and/or cell type.
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PMID:Minimal growth factor requirements of human fetal kidney in serum- and glucose-free culture. 136 49

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

The activities of 11 marker enzymes from the gastric and duodenal mucosa were determined in 15 patients with active duodenal ulcer disease before therapy, after 4 weeks of therapy with the prostaglandin E1 analogue misoprostol, 400 micrograms twice daily, and after another 4 weeks without any therapy. Another 15 patients were given a high-dose liquid antacid regimen. The activities were measured in homogenized material obtained with forceps through an endoscope. The healing rates of the two groups at 4 weeks were 53% and 80%, respectively. No changes in mucosal inflammation were noted during therapy. During treatment with misoprostol the activities in the descending duodenum of the membrane enzymes alkaline phosphatase, leucyl-beta-naphthylamidase, gamma-glutamyltransferase, and 5'-nucleotidase increased towards the values seen in normal controls. Despite a higher healing rate, no changes in the enzyme activities occurred in the group given high-dose antacid therapy. Four weeks after cessation of therapy the enzyme activities in the misoprostol group were not significantly different from the pretreatment values. In the biopsy specimens from the duodenal bulb the activities of monoamine oxidase fell during treatment with misoprostol and were restored to the pretreatment activity when therapy was stopped. In the stomach mucosa the enzyme activities were largely unchanged during treatment with both misoprostol and antacids. These results indicate that misoprostol and antacids have different mechanisms of action but may also suggest that the demonstrated enzymic changes are unrelated to the healing process.
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PMID:Effect of misoprostol and antacids on gastric and duodenal mucosal enzyme activities in duodenal ulcer patients. 190 58

We have examined the effect of induced hyper D3 vitaminosis on bone-related variables in the rat with special reference to the parathyroid (PTH)-sensitive adenylate cyclase (AC) in rat calvariae. Subcutaneous injections three times a week of doses theoretically corresponding to about 10 times the average physiological serum levels of either 25 hydroxyvitamin D3 (25OHD3), 1,25 dihydroxyvitamin D3 (1,25(OH)2D3), or 24,25 dihydroxyvitamin D3 (24,25(OH)2D3) for 12 weeks gave the following results: At 12 weeks of treatment, 24,25(OH)2D3 levels in the groups receiving 25OHD3 or 24,25(OH)2D3 increased significantly, whereas 1,25(OH)2D3 levels remained unaffected. Correspondingly, PTH-sensitive AC activities in crude calvarial membrane fractions from 25OHD3- and 24,25(OH)2D3-treated animals were obliterated. This effect was apparent after 4 weeks of treatment. In the group receiving 25OHD3, both basal, plus Gpp(NH)p-, and forskolin-sensitive AC activities were significantly reduced after 4 weeks of treatment. Similar effects in crude kidney membrane fractions were, however, not observed. Liver membranes from 25OHD3- or 24,25(OH)2D3-treated animals showed insignificant changes in the isoprenalin-, PGE1-, Gpp(NH)p-, or forskolin-sensitive AC activities. Finally, the significance of reduced PTH-sensitive bone AC activity has been assessed. 25OHD3 treatment yielded normocalcemic and hypercalciuric rats, whereas 1,25(OH)2D3 enhanced both serum and urine Ca2+ levels. 24,25(OH)2D3-treated and control animals were undiscernible in this respect. However, the 24,25-(OH)2D3 treatment caused reductions in both serum alkaline phosphatase levels and urinary hydroxyproline/creatinine ratio.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Long-term administration of vitamin D3 metabolites alters PTH-responsive osteoblastic adenylate cyclase in rats. 215 35

Bone cells derived from human trabecular explants display osteoblastic features. We examined the modulation of alkaline phosphatase activity and cAMP production as the result of exposing trabecular explants to physiologic concentrations of dexamethasone for 4 weeks during cellular outgrowth and subculture. Cells treated with dexamethasone were observed to grow generally more slowly than control cells. Cells appeared larger and more polygonal, and staining for alkaline phosphatase was more intense in the dexamethasone-exposed cultures. There was a progressive increase in cellular PTH responsiveness with increasing duration of exposure of cells to dexamethasone. Cells grown for 6 weeks in 3 x 10(-8) M dexamethasone had a 10-fold increase in PTH-stimulated cyclic AMP accumulation. Dexamethasone-treated cells also had a significantly increased alkaline phosphatase activity. 1,25-(OH)2D3-stimulated alkaline phosphatase activity was increased approximately 20-fold. cAMP responses were significantly increased to PTH (21.7-fold), PGE1 (2.67-fold), and forskolin (4.81-fold), but not to cholera toxin. Dexamethasone-treated cells also had a mean decrease in 1,25-(OH)2D3-stimulated osteocalcin production to 26.2% of control values (p less than 0.001). Hydrocortisone treatment gave rise to similar effects but of smaller magnitude than those of dexamethasone. Testosterone did not have a significant effect on alkaline phosphatase activity or cAMP production. Skin fibroblasts showed a significant enhancement of alkaline phosphatase activity in response to dexamethasone, but of a much smaller magnitude than in bone cells. The phenotypic changes induced by long-term culture in dexamethasone are consistent with the promotion of a more differentiated osteoblastic phenotype.
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PMID:Long-term effects of physiologic concentrations of dexamethasone on human bone-derived cells. 217 56

We investigated the in vitro effect of corticosteroids on the responsiveness of human cells of osteoblast lineage to parathyroid hormone (PTH). Prior to corticosteroid treatment, the cells demonstrated only a small increase in cAMP production and no measurable change in transmembrane potential in response to PTH. Exposure of cells to dexamethasone resulted in a 5-fold increase in PTH-induced cAMP production and in measurable PTH-induced membrane depolarization in all cells studied. The effect of corticosteroids on cAMP production was specific for PTH (not seen with PGE1 or forskolin), occurred in a time- and dose-dependent fashion and in the absence of cell proliferation. Most of the cells were of osteoblast lineage as determined by the presence of alkaline phosphatase activity and BGP secretion. These findings further support the idea that corticosteroids increase the sensitivity of cells of osteoblast lineage to PTH, perhaps by transforming cells which initially have a low responsiveness to PTH to a state of high responsiveness.
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PMID:Corticosteroid-induced changes in the responsiveness of human osteoblast-like cells to parathyroid hormone. 254 39

Proximal tubules were prepared from rat kidney cortex by collagenase digestion and purified by Percoll gradient centrifugation. Their enrichment was estimated by comparing the specific activities of various cell-specific enzymes in homogenates of renal cortex and of the isolated tubules. The tubules were cultured in a 50:50 mixture of Dulbecco's modified Eagle's and Ham's F12 media supplemented with insulin, transferrin, epidermal growth factor, hydrocortisone, and prostaglandin E1. After 2 to 3 d an extensive outgrowth of epithelial cells developed from the attached tubules. After 5 to 7 d near confluent monolayers were obtained. Hormonal responsiveness, marker enzyme activities, and transport properties were determined to further characterize the primary cultures. The cultured cells exhibited increased cyclic AMP production in response to parathyroid hormone but not calcitonin or vasopressin, consistent with the absence of cells derived from distal and collecting tubules. The cells also retained significant levels of 25-hydroxyvitamin D3-1 alpha-hydroxylase, alkaline phosphatase, and gamma-glytamyl-transpeptidase, three enzymes that are primarily associated with the proximal tubule. The cultured epithelial cells also exhibit a Na+-dependent phosphate and glucose transport systems. Therefore, the cells retain many functional properties that are characteristic of proximal tubules. Thus, the primary cultures should be suitable for the study of processes that occur specifically within this segment of the rat nephron.
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PMID:Characterization of primary cell cultures derived from rat renal proximal tubules. 254 89


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