Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The biotransformation of doxapram, a respiratory stimulant was studied with use of explants from human fetal livers (n = 15 fetuses) obtained from therapeutic abortions (gestational age, 10 to 20 weeks). Explants were cultured in Leibowitz medium and the media from cultured samples were collected before and at 3, 6, 12, and 24 hours after incubation with 2.5, 5.0, and 10 micrograms/ml doxapram. The concentrations of doxapram and its metabolites (AHR 0914, an analog of doxapram, AHR 5955 or ketodoxapram, and AHR 5904) were measured by high pressure liquid chromatography. Explant histopathology and alkaline phosphatase activity showed no direct toxic effects of the drug on liver tissue. The fastest rate of doxapram metabolism occurred during the first 3 hours of incubation (198 +/- 73.3, 438 +/- 63.3, and 538 +/- 62 ng/mg/hr liver protein at doxapram concentrations of 2.5, 5.0, and 10.0 micrograms/ml, respectively). At 3 hours of incubation, the amount of doxapram metabolized (nanogram per milligram of liver protein) was significantly higher (p less than 0.01) at doxapram concentrations of 10.0 (1616 +/- 186) and 5.0 microgram/ml (1315 +/- 190) than at 2.5 micrograms/ml (594 +/- 220). The oxidative pathway producing keto-doxapram, or AHR 5955 and AHR 5904, is more active than the de-ethylation producing the analog of doxapram AHR 0914. Data indicate substantial metabolism of doxapram by the human fetal lives.
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PMID:Doxapram metabolism in human fetal hepatic organ culture. 185 51

Dioxin and related chemicals cause a variety of toxic and biological effects via the aryl hydrocarbon receptor (AhR). We recently reported a mammalian cell-based bioassay system (dioxin-responsive-element-based sensing via secreted alkaline phosphatase; DRESSA) that can detect dioxin and dioxin-like chemicals with high sensitivity. In this report, we describe an advanced method (designated "fast-track DRESSA") that achieves fast, selective, and sensitive detection of dioxin and other toxic compounds. By optimization of assay conditions on cell number and serum concentration, the fast-track DRESSA enabled detection of 0.5 pM 2,3,7,8-tetrachlorodibenzo-p-dioxin within 6 h. It also enabled detection of 10 pM 3-methylcholanthrene, 100 pM benzo[a]pyrene, and 100 pM beta-naphthoflavone within 6-16 h. By combination with the AhR antagonist alpha-naphthoflavone, nonspecific, false-positive responses could be eliminated. Because of its time-saving property and easiness, sensitiveness, and specificity, the fast-track DRESSA would be advantageous for high-throughput screening of dioxin and dioxin-like compounds in environmental samples.
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PMID:Fast-track DRESSA: a bioassay for fast, sensitive, and selective detection of halogenated and polycyclic aromatic hydrocarbons. 1564 79

Cigarette smoke contains low levels of agonists for the aryl hydrocarbon receptor (AhR; also called the dioxin receptor). However, little is understood about the whole potential of cigarette smoke for activating AhR. In this report, we evaluated the total "dioxin-like" activity of cigarette smoke using in vitro and in vivo reporter systems. Cigarette smoke extract (CSE) was prepared from seven cigarette brands (1-20 mg tar content) and subjected to in vitro bioassay based on the xenobiotic-responsive element (XRE) as the sensor and secreted alkaline phosphatase (SEAP) as the reporter. Exposure of reporter cells to CSE triggered activation of XRE in a dose-dependent manner, which was suppressed by functional inhibition of AhR. Direct, brief exposure of the cells to cigarette smoke similarly induced activation of XRE. Using 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) as the standard, the XRE-activating potential (XAP) of individual smoke was evaluated quantitatively. Positive correlation was observed between the tar content and XAP values. The XAP values estimated were extremely high with a range from 18.5 to 51.2 ng 2,3,7,8-TCDD equivalent per cigarette. To further estimate XAP of cigarette smoke in vivo, we generated transgenic reporter mice that secrete SEAP under the control of XRE. After exposure of the mice to smoke, serum levels of SEAP were significantly elevated within 12 hours, peaked at 24 hours, and declined thereafter. These results evidenced for the first time that cigarette smoke has unexpectedly high dioxin-like potential that triggers the AhR-XRE pathway in vitro and in vivo.
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PMID:High levels of dioxin-like potential in cigarette smoke evidenced by in vitro and in vivo biosensing. 1684 60

The aim of this study was to evaluate drug metabolism in rat small intestinal and colon precision-cut slices during 24 h of incubation and the applicability of these slices for enzyme induction studies. Various parameters were evaluated: intracellular levels of ATP (general viability marker), alkaline phosphatase activity (specific epithelial marker), villin expression (specific epithelial marker), and metabolic rates of 7-ethoxycoumarin (CYP1A), testosterone (CYP3A and CYP2B), and 7-hydroxycoumarin (glucuronide and sulfate conjugation) conversions. ATP and villin remained constant up to, respectively, 5 and 8 h in small intestine and up to 24 h in colon. The metabolic rate remained constant in small intestinal slices up to 8 h and decreased afterward to 24 to 92%, depending on the substrate studied. The inducibility of metabolism in small intestinal and colon slices was tested with several inducers at various concentrations and incubation times. The following inducers were used: 3-methylcholanthrene, beta-naphthoflavone, indirubin, and tert-butylhydroquinone (aryl hydrocarbon receptor ligands), dexamethasone (glucocorticoid receptor/pregnane X receptor ligand) and phenobarbital (constitutive androstane receptor ligand). After incubation with inducers, metabolic rates were evaluated with 7-ethoxycoumarin and testosterone (phase I) and 7-hydroxycoumarin (phase II) as substrate. All inducers elevated the metabolic rates consistent with the available published in vivo induction data. Induction of enzyme activity was already detectable after 5 h (small intestine) and after 8 h (colon) for 3-methylcholanthrene and beta-naphthoflavone and was clearly detectable for all tested inducers after 24 h (up to 20-fold compared with noninduced controls). In conclusion, small intestinal and colon precision-cut slices are useful for metabolism and enzyme induction studies.
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PMID:Induction of phase I and II drug metabolism in rat small intestine and colon in vitro. 1734 36

Environmental pollutants including dioxins activate the aryl hydrocarbon receptor (AhR) and cause a wide range of pathologies. Development of AhR antagonists will be useful for prevention and treatment of the diseases related to AhR activation. Towards this goal, we aimed at seeking for potential AhR antagonists in herbal medicines using the dioxin responsive element-based sensing via secreted alkaline phosphatase (DRESSA). Through initial rough screening, 4 formulae were selected from 20 herbal medicines and subjected to the second, detailed screening. We found that only Formula bupleuri minor (TJ-9) significantly inhibited activation of AhR by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Among 7 raw herb extracts in TJ-9, Glycyrrhizae Radix and Scutellariae Radix were responsible for the antagonistic effect of TJ-9 against dioxin. Some constituents including Bupleuri Radix and Zingiberis Rhizoma rather activated AhR. Among 12 major constituents of Glycyrrhizae Radix and Scutellariae Radix, we identified that licopyranocoumarin, glycyrrhizic acid and genistein in Glycyrrhizae Radix and baicalein, wogonin and daidzein in Scutellariae Radix had substantial antagonistic effects on AhR. Among these, baicalein most effectively blocked activation of AhR triggered by cigarette smoke, a strong activator of AhR. The antagonistic substances identified here may be useful for prevention from diseases associated with aberrant activation of AhR.
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PMID:Blockade of the dioxin pathway by herbal medicine Formula Bupleuri Minor: identification of active entities for suppression of AhR activation. 1845 4

Environmental pollutants including halogenated and polycyclic aromatic hydrocarbons activate the aryl hydrocarbon receptor (AhR) and thereby cause a wide range of pathological changes. Development of AhR antagonists will be useful for prevention and treatment of diseases related to AhR activation. Towards this end, we aimed in the present study at seeking for potential inhibitors of the AhR pathway in mycelial extracts using the dioxin responsive element-based sensing via secreted alkaline phosphatase (DRESSA). Through the screening of 13 mycelia, extracts prepared from Phellinus linteus, Cordyceps militaris and Hericium erinaceum inhibited activation of AhR by 2,3,7,8-tetrachlorodibenzo-p-dioxin, benzo[a]pyrene or 3-methylcholanthrene. Subsequent studies revealed that only Phellinus linteus suppressed activation of AhR and AhR-dependent gene expression triggered by all of these agonists. Cigarette smoke is known to contain a number of halogenated and polycyclic aromatic hydrocarbons. We found that Phellinus linteus has the potential to block activation of AhR and AhR-dependent gene expression triggered by cigarette smoke. Furthermore, the inhibitory effect of Phellinus linteus on the AhR pathway was independent of; 1) depression of AhR or AhR nuclear translocator, and 2) induction of AhR repressor. We conclude that Phellinus linteus contains potent inhibitor(s) of AhR activation and may be useful for prevention of pathologies associated with aberrant activation of AhR.
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PMID:Blockade of the aryl hydrocarbon receptor pathway triggered by dioxin, polycyclic aromatic hydrocarbons and cigarette smoke by Phellinus linteus. 1882 49

Prunella vulgaris (PV), a commonly used Chinese herb, also known as Self-heal, has a wide range of reported medicinal activities. By screening multiple herbs using the endometrial cancer cell line, ECC-1, and an alkaline phosphatase detection assay, we found that PV displayed significant antiestrogenic activity. We investigated the possible usefulness of antiestrogenic activity using both in vitro and in vivo models of endometrial function. Using the well-differentiated, hormone-responsive endometrial cell line, ECC-1, PV extract, at concentrations that were not toxic to the cells, significantly reduced alkaline phosphatase activity and cell proliferation in response to estrogen in a dose-dependent manner. The expression of CYR61, an estrogen-induced protein, was blocked in ECC-1 cells by both the antiestrogen ICI 182,780 and PV extract. Interestingly, PV extract did not appear to directly inhibit estrogen signaling. Rather, we found that its activities were probably related to an ability to function as an aryl hydrocarbon receptor (AHR) agonist in ECC-1 cells. In support of this hypothesis, we noted that PV induced CYP1A1, CYP1B1, and AHR repressor expression in a dose-dependent manner--responses that were blocked by small interfering RNA treatment to reduce AHR and specific AHR antagonists. Ovariectomized immunodeficient RAG-2/gamma(c) knockout mice implanted with human endometrial xenografts developed implants only when treated with estrogen. Mice treated with estrogen and PV tea in their drinking water had fewer and smaller xenograft implants compared with their estrogen-treated counterparts that drank only water (P < 0.05). Analysis of the resulting implants by immunohistochemistry demonstrated persistent estrogen receptor (ER), but reduced proliferation and CYR61 expression. Mouse uterine tissue weight in PV-treated mice was not different from controls, and cycle fecundity of intact C57 female mice was unaffected by PV tea treatment. PV, or Self-heal, exhibits significant antiestrogenic properties, both in vitro and in vivo. This activity is likely due to the ability of PV-activated AHR to interfere with estrogen. This herb may be useful as an adjunct for the treatment of estrogen-dependent processes like endometriosis and breast and uterine cancers. Full characterization of this herb will likely provide new insights into the crosstalk between AHR and ESR1, with potential for therapeutic applications in women.
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PMID:Characterization of antiestrogenic activity of the Chinese herb, prunella vulgaris, using in vitro and in vivo (Mouse Xenograft) models. 1892 63

We have previously shown that the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) affects bone growth, modelling and mechanical strength in vivo. In this study, we utilized differentiation of bone marrow stem cells to osteoblasts and osteoclasts as a model system to study the effects of TCDD on bones. Stem cells were isolated from bone marrow of femurs and tibias of rats and mice. Progress of osteoblastic differentiation was monitored by measuring mRNA expression levels of differentiation markers from control and TCDD-treated cells using quantitative RT-PCR. TCDD significantly and dose-dependently decreased the mRNA levels of RUNX2, alkaline phosphatase and osteocalcin. Also the activity of alkaline phosphatase was significantly inhibited in both rat and mice cells. In the case of osteoclasts, TCDD decreased the number of TRACP+ multinucleated cells, with corresponding decreases in the number of F-actin rings and the area of resorption. Studies in AHR-knockout mice indicated that TCDD has no effect on the expression of osteoblastic differentiation markers suggesting that TCDD mediates its effects by AHR. Both osteoblastic and osteoclastic effects took place at very low doses of TCDD, as in most cases 100 fM TCDD was enough to significantly affect the differentiation markers. Therefore, differentiation of osteoblasts and osteoclasts from bone marrow stem cells seems to be a very sensitive target for TCDD. Disrupting effects in osteoblastic cells, in addition to disturbed osteoclastogenesis, may thus play a role in adverse effects on bone quality in TCDD exposed animals.
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PMID:Dioxins interfere with differentiation of osteoblasts and osteoclasts. 1926 58

Halogenated and polycyclic aromatic hydrocarbons are widely distributed pollutants in environments. These toxic substances activate the aryl hydrocarbon receptor (AhR) and thereby cause a broad spectrum of pathological changes. Development of AhR inhibitors will be useful for prevention of diseases caused by AhR activation. Using the dioxin responsive element (DRE)-based sensing via secreted alkaline phosphatase (DRESSA), we examined effects of Antrodia camphorata, a mycerial extract, on the activation of AhR by halogenated and polycyclic aromatic hydrocarbons. We found that Antrodia camphorata markedly suppressed activation of AhR triggered by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In contrast, activation of AhR by polycyclic aromatic hydrocarbons (benzo[a]pyrene and 3-methylcholanthrene) was inhibited only modestly by this mycelium. Similarly, Antrodia camphorata only mildly attenuated activation of AhR by cigarette smoke that contains polycyclic aromatic hydrocarbons. Consistent with these results, Northern blot analysis revealed that DRE-driven exogenous and endogenous gene expression triggered by TCDD was abolished by Antrodia camphorata, whereas it did not substantially affect DRE-induced transcription triggered by benzo[a]pyrene, 3-methylcholanthrene or cigarette smoke. We also found that the inhibitory effect of Antrodia camphorata on TCDD-induced AhR activation was ascribed to neither down-regulation of AhR, down-regulation of the AhR nuclear translocator, nor up-regulation of the AhR repressor. These results suggest that Antrodia camphorata preferentially inhibits AhR activation and DRE-dependent gene expression triggered by dioxin.
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PMID:Preferential blockade of dioxin-induced activation of the aryl hydrocarbon receptor by Antrodia camphorata. 1972 Dec 24

Many phytochemicals are known to exert cancer chemopreventive activity by eliminating chemical carcinogens or toxic xenobiotics through the action of detoxification enzymes. In this study, we investigated the cancer chemopreventive effects of youngiasides isolated from Crepidiastrum denticulatum. These youngiasides significantly induced quinone reductase (QR) activity in mouse hepatoma Hepa-1c1c7 cells, and showed a relatively high chemoprevention index (CI; divided IC(50) value with CD value). The youngiasides also significantly induced transcriptional activation of QR in Hepa-QR-secreted alkaline phosphatase (SEAP) cells, which is a stable cell line containing the intact promoter region of QR. In order to determine if upregulation of QR by the youngiasides was mediated through a mono-functional or bi-functional mechanism, we examined the nuclear factor-E2 p45-related factor 2(Nrf2)-antioxidant response element (ARE) and aryl hydrocarbon receptor (AhR)-xenobiotic response element (XRE) pathways, which are two major pathways, involved in regulation of Phase I and/or Phase II detoxification enzymes. The youngiasides increased the cytochrome P450 1A1 (CYP1A1) mRNA and protein levels in human colorectal cancer Caco-2 cells and also increased the QR mRNA and protein levels in Caco-2 cells through ARE and XRE activation which resulted from translocation of Nrf2 and AhR into the nucleus. These results suggest that regulation of QR by the youngiasides was due to bi-functional induction through the Nrf2-ARE and AhR-XRE pathways. Thus, these youngiasides as bi-functional inducers of QR have potential as cancer chemopreventive agents.
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PMID:Bi-functional induction of the quinone reductase and cytochrome P450 1A1 by youngiasides via Nrf2-ARE and AhR-XRE pathways. 2093 Mar 71


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