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Ann M Simpson - One of the best experts on this subject based on the ideXlab platform.
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pancreatic transdifferentiation and glucose regulated production of human insulin in the h4iie rat Liver Cell Line
International Journal of Molecular Sciences, 2016Co-Authors: M A Swan, Najah T Nassif, Bronwyn A Obrien, Nichole Joachim, Rosetta Martiniellowilks, Ann M SimpsonAbstract:Due to the limitations of current treatment regimes, gene therapy is a promising strategy being explored to correct blood glucose concentrations in diabetic patients. In the current study, we used a retroviral vector to deLiver either the human insulin gene alone, the rat NeuroD1 gene alone, or the human insulin gene and rat NeuroD1 genes together, to the rat Liver Cell Line, H4IIE, to determine if storage of insulin and pancreatic transdifferentiation occurred. Stable clones were selected and expanded into Cell Lines: H4IIEins (insulin gene alone), H4IIE/ND (NeuroD1 gene alone), and H4IIEins/ND (insulin and NeuroD1 genes). The H4IIEins Cells did not store insulin; however, H4IIE/ND and H4IIEins/ND Cells stored 65.5 ± 5.6 and 1475.4 ± 171.8 pmol/insulin/5 × 106 Cells, respectively. Additionally, several β Cell transcription factors and pancreatic hormones were expressed in both H4IIE/ND and H4IIEins/ND Cells. Electron microscopy revealed insulin storage vesicles in the H4IIE/ND and H4IIEins/ND Cell Lines. Regulated secretion of insulin to glucose (0–20 mmol/L) was seen in the H4IIEins/ND Cell Line. The H4IIEins/ND Cells were transplanted into diabetic immunoincompetent mice, resulting in normalization of blood glucose. This data shows that the expression of NeuroD1 and insulin in Liver Cells may be a useful strategy for inducing islet neogenesis and reversing diabetes.
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reversal of diabetes following transplantation of an insulin secreting human Liver Cell Line melligen Cells
Molecular therapy. Methods & clinical development, 2015Co-Authors: Janet Lawandi, Anne M Swan, P F Williams, Dora Ling, Najah T Nassif, F R Torpy, Bronwyn A Obrien, Ann M SimpsonAbstract:As an alternative to the transplantation of islets, a human Liver Cell Line has been genetically engineered to reverse type 1 diabetes (TID). The initial Liver Cell Line (Huh7ins) commenced secretion of insulin in response to a glucose concentration of 2.5 mmol/l. After transfection of the Huh7ins Cells with human islet glucokinase, the resultant Melligen Cells secreted insulin in response to glucose within the physiological range; commencing at 4.25 mmol/l. Melligen Cells exhibited increased glucokinase enzymatic activity in response to physiological glucose concentrations, as compared with Huh7ins Cells. When transplanted into diabetic immunoincompetent mice, Melligen Cells restored normoglycemia. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed that both Cell Lines expressed a range of β-Cell transcription factors and pancreatic hormones. Exposure of Melligen and Huh7ins Cells to proinflammatory cytokines (TNF-α, IL-1β, and IFN-γ) affected neither their viability nor their ability to secrete insulin to glucose. Gene expression (microarray and qRT-PCR) analyses indicated the survival of Melligen Cells in the presence of known β-Cell cytotoxins was associated with the expression of NF-κB and antiapoptotic genes (such as BIRC3). This study describes the successful generation of an artificial β-Cell Line, which, if encapsulated to avoid allograft rejection, may offer a clinically applicable cure for T1D.
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899. Glucose-Stimulated Insulin Secretion from an Engineered Human Liver Cell Line Is Regulated by ATP-Sensitive Potassium Channels and the L-Type Calcium Channel
Molecular Therapy, 2005Co-Authors: Ann M Simpson, Donald K. Martin, Mark Lutherborrow, Bernard E TuchAbstract:Introduction: One approach to the treatment of Type 1 diabetes is the creation of an 'artificial beta Cell'. The stable transfection of insulin cDNA into the human Liver Cell Line Huh7 resulted in synthesis, storage and regulated release of insulin to a glucose stimulus (Huh7ins Cells). The aim of the present study was to determine if Huh7ins Cells respond to glucose via activation of ATP-sensitve potassium channels (KATP) and voltage-gated calcium channels, as is the case with pancreatic beta Cells.
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function of a genetically modified human Liver Cell Line that stores processes and secretes insulin
Gene Therapy, 2003Co-Authors: Bernard E Tuch, B Szymanska, Muhammad T Tabiin, David J Gross, Sara Holman, Anne M Swan, R K Humphrey, Glenn M Marshall, Ann M SimpsonAbstract:Function of a genetically modified human Liver Cell Line that stores, processes and secretes insulin
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Function of a genetically modified human Liver Cell Line that stores, processes and secretes insulin
Gene Therapy, 2003Co-Authors: Bernard E Tuch, B Szymanska, Muhammad T Tabiin, David J Gross, Sara Holman, R K Humphrey, Glenn M Marshall, M Yao, M Anne Swan, Ann M SimpsonAbstract:An alternative approach to the treatment of type I diabetes is the use of genetically altered neoplastic Liver Cells to synthesize, store and secrete insulin. To try and achieve this goal we modified a human Liver Cell Line, HUH7, by transfecting it with human insulin cDNA under the control of the cytomegalovirus promoter. The HUH7-ins Cells created were able to synthesize insulin in a similar manner to that which occurs in pancreatic β Cells. They secreted insulin in a regulated manner in response to glucose, calcium and theophylLine, the dose–response curve for glucose being near-physiological. Perifusion studies showed that secretion was rapid and tightly controlled. Removal of calcium resulted in loss of glucose stimulation while addition of brefeldin A resulted in a 30% diminution of effect, indicating that constitutive release of insulin occurred to a small extent. Insulin was stored in granules within the cytoplasm. When transplanted into diabetic immunoincompetent mice, the Cells synthesized, processed, stored and secreted diarginyl insulin in a rapid regulated manner in response to glucose. Constitutive release of insulin also occurred and was greater than regulated secretion. Blood glucose levels of the mice were normalized but ultimately became subnormal due to continued proliferation of Cells. Examination of the HUH7-ins Cells as well as the parent Cell Line for β Cell transcription factors showed the presence of NeuroD but not PDX-1. PC1 and PC2 were also present in both Cell types. Thus, the parent HUH7 Cell Line possessed a number of endocrine pancreatic features that reflect the common endodermal ancestry of Liver and pancreas, perhaps as a result of ontogenetic regression of the neoplastic Liver Cell from which the Line was derived. Introduction of the insulin gene under the control of the CMV promoter induced changes in these Cells to make them function to some extent like pancreatic β Cells. Our results support the view that neoplastic Liver Cells can be induced to become substitute pancreatic β Cells and become a therapy for the treatment of type I diabetes.
Niels C. Bols - One of the best experts on this subject based on the ideXlab platform.
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single and combined toxicity of pharmaceuticals and personal care products ppcps on the rainbow trout Liver Cell Line rtl w1
Aquatic Toxicology, 2009Co-Authors: Sabine Schnell, Niels C. Bols, Carlos Barata, Cinta PorteAbstract:Abstract The toxicological implications of the presence of pharmaceuticals and personal care products (PPCPs) in the aquatic environment remain largely unknown. Acute toxicity tests have generally failed to detect the subtle action elicited by those compounds at environmentally relevant concentrations and they have often overlooked the fact that toxicity can be influenced by additive and synergistic effects. The aim of this study was to further assess the cytotoxicity of different pharmaceuticals and synthetic musks as well as their mixtures on the rainbow trout Liver Cell Line RTL-W1. Eleven pharmaceuticals from different therapeutic classes (anti-inflammatory drugs, serotonin re-uptake inhibitors and lipid regulators) and five synthetic musks from the two major groups (nitro- and polycyclic musks) were selected for the study. Two fluorescent dyes were used to monitor Cell viability. Among the tested compounds, estimated EC50s (effective concentration causing 50% decLine of Cell viability) denoted that polycyclic musks (7–25 μM) followed by anti-depressives (7–50 μM) showed the highest potential to induce cytotoxicity, whereas lipid regulators (20–380 μM), anti-inflammatory drugs (160–260 μM) and nitromusks (100–240 μM) had the lowest toxicity. Within a given therapeutic class, combined toxicity of mixtures was additive, following in most cases the concentration addition concept. However, the combined toxicity was higher than additive for those mixtures that included one compound from each class (i.e. dissimilar mixtures). Overall, this study shows that in the aquatic environment, toxicity of PPCPs on non-target organisms may occur at concentrations lower than expected due to synergistic effects between the different toxicants.
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polycyclic aromatic hydrocarbons as inducers of cytochrome p4501a enzyme activity in the rainbow trout Liver Cell Line rtl w1 and in primary cultures of rainbow trout hepatocytes
Environmental Toxicology and Chemistry, 2001Co-Authors: Anja Behrens, Kristin Schirmer, Niels C. Bols, Helmut SegnerAbstract:In order to investigate Cell-specific differences in the response of in vitro models to environmental toxicants, we compared the capacity of nine polycyclic aromatic hydrocarbons (PAHs) to induce cytochrome P4501A (CYP1A) in primary rainbow trout (Oncorhynchus mykiss) hepatocytes and a rainbow trout Liver Cell Line, RTL-W1. Induction of CYP1A was estimated from the catalytic activity of 7-ethoxyresorufin-O-deethylase (EROD) and compared by median effective concentration (EC50) values, induction spans, and benzo[a]pyrene induction equivalency factors for inducing PAHs. The influence of culture conditions was investigated with respect to the presence or absence of serum and varying exposure times. Both in vitro systems lead to an identical classification of the PAHs in noninducing (anthracene, fluoranthene, phenanthrene, and pyrene) and inducing compounds with a similar ranking of inducing PAHs. Mean EC50 values in RTL-W1 Cells were, respectively, 343 and 266 nM far benzo[a]anthracene, 57 and 92 nM for BaP, 134 and 283 nM for benzo[b]fluoranthene, 455 and 270 nM for chrysene, and 98 and 116 nM for 3-methylcholanthrene. Compared to primary hepatocytes, the RTL-W1 Cell Line was more sensitive in its EROD response to the presence or absence of serum and to the increase in exposure time, which led to higher EC50 values.
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transient induction of 7 ethoxyresorufin o deethylase erod activity by medium change in the rainbow trout Liver Cell Line rtl w1
Marine Environmental Research, 2000Co-Authors: Helmut Segner, Anja Behrens, E M Joyce, Kristin Schirmer, Niels C. BolsAbstract:Cytochrome P4501A (CYP1A) metabolizes a wide array of lipophilic xenobiotics. In fish Liver, CYP1A is constitutively expressed at low levels, but xenobiotics can strongly induce CYP1A expression via a receptor-mediated pathway. While induction of hepatic CYP1A in teleosts by xenobiotics is well investigated, very little is known on the regulation of constitutive CYP1A expression and its induction by factors other than xenobiotics. In the present study we show that in the rainbow trout Liver Cell Line, RTL-W1, CYP1A-catalyzed 7-ethoxyresorufin-O-deethylase (EROD) activity can be induced by a change of the culture medium, in the absence of xenobiotics. The increase in Cellular EROD levels is of transient nature. Experiments with Cell incubation solutions supplemented with various medium components indicate that photooxidized tryptophan is the agent causing the increase of EROD activity after medium change.
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ability of polycyclic aromatic hydrocarbons to induce 7 ethoxyresorufin o deethylase activity in a trout Liver Cell Line
Ecotoxicology and Environmental Safety, 1999Co-Authors: Niels C. Bols, E M Joyce, Kristin Schirmer, D G Dixon, Bruce M Greenberg, Jeffrey J WhyteAbstract:Along with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 24 unsubstituted polycyclic aromatic hydrocarbons (PAHs) were evaluated for their ability to induce 7-ethoxyresorufin-o-deethylase (EROD) activity in the rainbow trout Liver Cell Line RTL-W1. When the duration and Cell density of exposure were increased, the EC(50) for EROD induction was relatively constant for TCDD, but increased for PAHs. Regardless of exposure conditions, EROD activity was not induced by 9 PAHs: naphthalene, phenanthrene, anthracene, pyrene, perylene, acenaphthylene, acenaphthene, fluorene, and fluoranthene. Two PAHs, benzo[g,h,i]perylene and coronene, induced EROD activity inconsistently. The remaining 13 PAHs consistently induced EROD activity. The EC(50)s for induction exhibited approximately a 110-fold range. The order of potency, from most to least potent, was benzo[k]fluoranthene, dibenzo[a,i]pyrene, dibenzo [a,h]anthracene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, benzo [b]fluoranthene, pentacene, benzo[b]anthracene, benzo[b] fluorene, chrysene, benzo[a]anthracene, benzo[e]pyrene, and triphenylene. When the induction potency was expressed relative to TCDD, the toxic equivalency factors (TEFs) ranged from 0.001 to 0.000 01. When expressed relative to benzo[a]pyrene, the TEFs ranged from 3.44 to 0. 03.
King Ming Chan - One of the best experts on this subject based on the ideXlab platform.
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toxic effects of triclosan on a zebrafish danio rerio Liver Cell Line zfl
Aquatic Toxicology, 2017Co-Authors: Zhou Zhou, Jie Yang, King Ming ChanAbstract:Abstract Triclosan (TCS, 5-chloro-2-(2,4-dichlorophenoxy) phenol) is an antimicrobial agent widely used in personal care products. It has been detected in surface water, soil, aquatic species, and even humans. In this study, we used zebrafish (Danio rerio) as a model to test the hypothesis that TCS exhibits toxic effects by interacting with thyroid hormone receptor β (TRβ) and aryl hydrocarbon receptor (AhR) and by inducing the transcription of thyroid hormone (TH)-associated genes and affecting phase I and phase II enzymes. The median lethal concentrations (LC50) of TCS in zebrafish embryos/larvae and a zebrafish Liver Cell Line (ZFL) were first determined. Hatched larvae were most sensitive to TCS exposure, with LC50 values ranging from 1.26 to 1.46 μM for 96 h after hatching exposure. The major effect of TCS was delayed hatching which occurred from 1.13 μM. The constructed GFP–zfTRβ fusion protein revealed the subCellular location of zfTRβ as the nucleus in both T3-induced and uninduced states, adding to the difficulty of studying TCS action on thyroid hormone receptors in ZFL Cells. TCS had neither agonistic nor antagonistic effects on zfTRβLBD or AhR from the reporter gene systems. Ethoxyresorufin-o-deethylase (EROD) assay suggested that TCS is a weak P4501a (Cyp1a) agonist at 5 μM and that it inhibits cytochrome Cyp1a activity induced by benzo(a)pyrene (BaP). In time course-based mRNA profiling in ZFL Cells, 4-h exposure to TCS caused a significant (up to 37.5-fold) inhibition of Cyp1a at 2.5 μM. An overall inhibition of Liver phase I and II gene transcription at 4 h exposure indicates the possible quick catabolism of TCS. Our findings suggest that TCS is not a TH mimic that affects TH-related gene expression. The impairment of Cyp1a mRNA expression could be due to stimulation by other stressors such as oxidative stress, warranting further investigation into the underlying mechanism in zebrafish.
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evaluation of the toxic effects of brominated compounds bde 47 99 209 tbbpa and bisphenol a bpa using a zebrafish Liver Cell Line zfl
Aquatic Toxicology, 2015Co-Authors: Jie Yang, King Ming ChanAbstract:Abstract The toxic effects of three polybrominated diphenyl ether (PBDE) congeners (BDE-47, -99, and -209), tetrabromobisphenol A (TBBPA) and bisphenol A (BPA), were evaluated by determining their 24 h and 96 h median lethal concentrations using a zebrafish Liver Cell Line, ZFL. It was found that BDE-47, BDE-99 and TBBPA showed comparative cytotoxicity within the range of 1.2–4.2 μM, and were more toxic than BPA (367.1 μM at 24 h and 357.6 μM at 96 h). However, BDE-209 induced only 15% lethality with exposures up to 25 μM. The molecular stresses of BDE-47, -99, TBBPA and BPA involved in thyroid hormone (TH) homeostasis and hepatic metabolism were also investigated. Using a reporter gene system to detect zebrafish thyroid hormone receptor β (zfTRβ) transcriptional activity, the median effective concentration of triiodothyronine (T3) was determined to be 9.2 × 10−11 M. BDE-47, BDE-99, TBBPA and BPA alone, however, did not exhibit zfTRβ agonistic activity. BPA displayed T3 (0.1 nM) induced zfTRβ antagonistic activity with a median inhibitory concentration of 19.3 μM. BDE-47, BDE-99 and TBBPA displayed no antagonistic effects of T3-induced zfTRβ activity. Target gene expressions were also examined under acute exposures. The significant inhibition of different types of deiodinases by all of the test chemicals indicated TH circulation disruption. All four chemicals, especially BPA, were able to affect transcripts of phase II hepatic metabolizing enzymes (UGT2A1, SULT1) in vitro. In conclusion, the zfTRβ reporter gene system developed here helps deLineate an in vitro model to enable the analysis of the TH disruption effects of environmental pollutants in fish. BPA and the brominated compounds tested were able to disrupt the TH system at the gene expression level, probably through the deiodination pathways.
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mechanism of cadmium induced cytotoxicity on the zfl zebrafish Liver Cell Line
Metallomics, 2012Co-Authors: King Ming ChanAbstract:The cadmium ion (Cd2+) is a highly toxic metal ion; however, its hepatic toxic effects are not very well characterized in a systematic manner. In this study, a zebrafish Liver Cell Line, ZFL was used as a model to investigate the mechanism of Cd2+-induced cytotoxicity on hepatocytes. The intraCellular level of reactive oxygen species decreased following the administration of Cd2+; antioxidant levels and related enzyme activities and gene expression were detected, showing that the toxic effects of Cd2+ might not be coupled to oxidative stress. To understand the cytotoxic effects of Cd2+ on ZFL Cells after Cd2+ exposure, a total of 77 differentially expressed proteins were detected by two-dimensional gel electrophoresis; 43 of them were further identified by MALDI-TOF-MS. The proteins that responded to Cd2+ in ZFL Cells were related to stress response, transporters, regulation of transcription, redox homeostasis, or different signaling pathways, with half of these proteins having metal ion binding capabilities.
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effects of cu2o nanoparticle and cucl2 on zebrafish larvae and a Liver Cell Line
Aquatic Toxicology, 2011Co-Authors: Dongshi Chen, Dieqing Zhang, Jimmy C Yu, King Ming ChanAbstract:Abstract The extensive uses of nanomaterials have caused many concerns of their potential hazards to the aquatic environments. As partial dissolution of metal nanoparticles may occur, it is important to study the toxic effects of nanoparticles and determine the no observable effect levels (NOELs) and lowest observable effect levels (LOELs) of these materials in water by using biomarker genes’ expression in zebrafish (Danio rerio). In this study, the toxic effects of Cu2O nanoparticle (NP) on zebrafish larvae and zebrafish Liver Cell-Line (ZFL) were evaluated by determining their 96 h LC50 values (zebrafish larvae: 242.4 ppb; ZFL: 110 ppm), which was less toxic than CuCl2 (zebrafish larvae: 85.73 ppb; ZFL: 23.04 ppm). However, zebrafish larvae are sensitive to both Cu2O NP and CuCl2. We also examined the effects of elevated Cu2O NP and CuCl2 on the expression of several copper related genes in zebrafish larvae by using real-time quantitative polymerase chain reaction. It was found that Cu2O NP and CuCl2 induced the mRNA levels of metallothionein (MT), Cu/Zn superoxide dismutase (Cu/Zn SOD), metal regulatory transcription factor 1 (MTF1) and copper transporters, ATP7A and 7B, but down-regulated the mRNA levels of glutathione sulfur transferase (GST). Interestingly, the inductions of MT, ATP7A and ATP7B in the Cu2O NP exposure groups were much higher than that of the CuCl2 exposure groups, and resulted in higher copper accumulation in the Cu2O NP exposure groups. Furthermore, as determined by using MT, ATP7A and ATP7B gene expression, the NOELs of CuCl2 and Cu2O NP were 11 ppb and 30 ppb whereas the LOELs of CuCl2 and Cu2O NP were 43 ppb and 121 ppb, respectively.
Helmut Segner - One of the best experts on this subject based on the ideXlab platform.
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polycyclic aromatic hydrocarbons as inducers of cytochrome p4501a enzyme activity in the rainbow trout Liver Cell Line rtl w1 and in primary cultures of rainbow trout hepatocytes
Environmental Toxicology and Chemistry, 2001Co-Authors: Anja Behrens, Kristin Schirmer, Niels C. Bols, Helmut SegnerAbstract:In order to investigate Cell-specific differences in the response of in vitro models to environmental toxicants, we compared the capacity of nine polycyclic aromatic hydrocarbons (PAHs) to induce cytochrome P4501A (CYP1A) in primary rainbow trout (Oncorhynchus mykiss) hepatocytes and a rainbow trout Liver Cell Line, RTL-W1. Induction of CYP1A was estimated from the catalytic activity of 7-ethoxyresorufin-O-deethylase (EROD) and compared by median effective concentration (EC50) values, induction spans, and benzo[a]pyrene induction equivalency factors for inducing PAHs. The influence of culture conditions was investigated with respect to the presence or absence of serum and varying exposure times. Both in vitro systems lead to an identical classification of the PAHs in noninducing (anthracene, fluoranthene, phenanthrene, and pyrene) and inducing compounds with a similar ranking of inducing PAHs. Mean EC50 values in RTL-W1 Cells were, respectively, 343 and 266 nM far benzo[a]anthracene, 57 and 92 nM for BaP, 134 and 283 nM for benzo[b]fluoranthene, 455 and 270 nM for chrysene, and 98 and 116 nM for 3-methylcholanthrene. Compared to primary hepatocytes, the RTL-W1 Cell Line was more sensitive in its EROD response to the presence or absence of serum and to the increase in exposure time, which led to higher EC50 values.
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transient induction of 7 ethoxyresorufin o deethylase erod activity by medium change in the rainbow trout Liver Cell Line rtl w1
Marine Environmental Research, 2000Co-Authors: Helmut Segner, Anja Behrens, E M Joyce, Kristin Schirmer, Niels C. BolsAbstract:Cytochrome P4501A (CYP1A) metabolizes a wide array of lipophilic xenobiotics. In fish Liver, CYP1A is constitutively expressed at low levels, but xenobiotics can strongly induce CYP1A expression via a receptor-mediated pathway. While induction of hepatic CYP1A in teleosts by xenobiotics is well investigated, very little is known on the regulation of constitutive CYP1A expression and its induction by factors other than xenobiotics. In the present study we show that in the rainbow trout Liver Cell Line, RTL-W1, CYP1A-catalyzed 7-ethoxyresorufin-O-deethylase (EROD) activity can be induced by a change of the culture medium, in the absence of xenobiotics. The increase in Cellular EROD levels is of transient nature. Experiments with Cell incubation solutions supplemented with various medium components indicate that photooxidized tryptophan is the agent causing the increase of EROD activity after medium change.
Kristin Schirmer - One of the best experts on this subject based on the ideXlab platform.
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polycyclic aromatic hydrocarbons as inducers of cytochrome p4501a enzyme activity in the rainbow trout Liver Cell Line rtl w1 and in primary cultures of rainbow trout hepatocytes
Environmental Toxicology and Chemistry, 2001Co-Authors: Anja Behrens, Kristin Schirmer, Niels C. Bols, Helmut SegnerAbstract:In order to investigate Cell-specific differences in the response of in vitro models to environmental toxicants, we compared the capacity of nine polycyclic aromatic hydrocarbons (PAHs) to induce cytochrome P4501A (CYP1A) in primary rainbow trout (Oncorhynchus mykiss) hepatocytes and a rainbow trout Liver Cell Line, RTL-W1. Induction of CYP1A was estimated from the catalytic activity of 7-ethoxyresorufin-O-deethylase (EROD) and compared by median effective concentration (EC50) values, induction spans, and benzo[a]pyrene induction equivalency factors for inducing PAHs. The influence of culture conditions was investigated with respect to the presence or absence of serum and varying exposure times. Both in vitro systems lead to an identical classification of the PAHs in noninducing (anthracene, fluoranthene, phenanthrene, and pyrene) and inducing compounds with a similar ranking of inducing PAHs. Mean EC50 values in RTL-W1 Cells were, respectively, 343 and 266 nM far benzo[a]anthracene, 57 and 92 nM for BaP, 134 and 283 nM for benzo[b]fluoranthene, 455 and 270 nM for chrysene, and 98 and 116 nM for 3-methylcholanthrene. Compared to primary hepatocytes, the RTL-W1 Cell Line was more sensitive in its EROD response to the presence or absence of serum and to the increase in exposure time, which led to higher EC50 values.
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transient induction of 7 ethoxyresorufin o deethylase erod activity by medium change in the rainbow trout Liver Cell Line rtl w1
Marine Environmental Research, 2000Co-Authors: Helmut Segner, Anja Behrens, E M Joyce, Kristin Schirmer, Niels C. BolsAbstract:Cytochrome P4501A (CYP1A) metabolizes a wide array of lipophilic xenobiotics. In fish Liver, CYP1A is constitutively expressed at low levels, but xenobiotics can strongly induce CYP1A expression via a receptor-mediated pathway. While induction of hepatic CYP1A in teleosts by xenobiotics is well investigated, very little is known on the regulation of constitutive CYP1A expression and its induction by factors other than xenobiotics. In the present study we show that in the rainbow trout Liver Cell Line, RTL-W1, CYP1A-catalyzed 7-ethoxyresorufin-O-deethylase (EROD) activity can be induced by a change of the culture medium, in the absence of xenobiotics. The increase in Cellular EROD levels is of transient nature. Experiments with Cell incubation solutions supplemented with various medium components indicate that photooxidized tryptophan is the agent causing the increase of EROD activity after medium change.
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ability of polycyclic aromatic hydrocarbons to induce 7 ethoxyresorufin o deethylase activity in a trout Liver Cell Line
Ecotoxicology and Environmental Safety, 1999Co-Authors: Niels C. Bols, E M Joyce, Kristin Schirmer, D G Dixon, Bruce M Greenberg, Jeffrey J WhyteAbstract:Along with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 24 unsubstituted polycyclic aromatic hydrocarbons (PAHs) were evaluated for their ability to induce 7-ethoxyresorufin-o-deethylase (EROD) activity in the rainbow trout Liver Cell Line RTL-W1. When the duration and Cell density of exposure were increased, the EC(50) for EROD induction was relatively constant for TCDD, but increased for PAHs. Regardless of exposure conditions, EROD activity was not induced by 9 PAHs: naphthalene, phenanthrene, anthracene, pyrene, perylene, acenaphthylene, acenaphthene, fluorene, and fluoranthene. Two PAHs, benzo[g,h,i]perylene and coronene, induced EROD activity inconsistently. The remaining 13 PAHs consistently induced EROD activity. The EC(50)s for induction exhibited approximately a 110-fold range. The order of potency, from most to least potent, was benzo[k]fluoranthene, dibenzo[a,i]pyrene, dibenzo [a,h]anthracene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, benzo [b]fluoranthene, pentacene, benzo[b]anthracene, benzo[b] fluorene, chrysene, benzo[a]anthracene, benzo[e]pyrene, and triphenylene. When the induction potency was expressed relative to TCDD, the toxic equivalency factors (TEFs) ranged from 0.001 to 0.000 01. When expressed relative to benzo[a]pyrene, the TEFs ranged from 3.44 to 0. 03.