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Capinha L, Jennings P, Commandeur JNM. Bioactivation of trichloroethylene to three regioisomeric glutathione conjugates by liver fractions and recombinant human glutathione transferases: Species differences and implications for human risk assessment. Toxicol Lett 2021; 341:94-106. [PMID: 33539969 DOI: 10.1016/j.toxlet.2021.01.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 11/18/2022]
Abstract
Enzymatic conjugation of glutathione (GSH) to trichloroethylene (TCE) followed by catabolism to the corresponding cysteine-conjugate, S-(dichlorovinyl)-L-cysteine (DCVC), and subsequent bioactivation by renal cysteine conjugate beta-lyases is considered to play an important role in the nephrotoxic effects observed in TCE-exposed rat and human. In this study, it is shown for the first time that three regioisomers of GSH-conjugates of TCE are formed by rat and human liver fractions, namely S-(1,2-trans-dichlorovinyl)-glutathione (1,2-trans-DCVG), S-(1,2-cis-dichlorovinyl)-glutathione (1,2-cis-DCVG) and S-(2,2-dichlorovinyl)-glutathione (2,2-DCVG). In incubations of TCE with rat liver fractions their amounts decreased in order of 1,2-cis-DCVG > 1,2-trans-DCVG > 2,2-DCVG. Human liver cytosol showed a more than 10-fold lower activity of GSH-conjugation, with amounts of regioisomers decreasing in order 2,2-DCVG > 1,2-trans-DCVG > 1,2-cis-DCVG. Incubations with recombinant human GSTs suggest that GSTA1-1 and GSTA2-2 play the most important role in human liver cytosol. GSTP1-1, which produces regioisomers in order 1,2-trans-DCVG > 2,2-cis-DCVG > 1,2-cis-DCVG, is likely to contribute to extrahepatic GSH-conjugation of TCE. Analysis of the products formed by a beta-lyase mimetic model showed that both 1,2-trans-DCVC and 1,2-cis-DCVC are converted to reactive products that form cross-links between the model nucleophile 4-(4-nitrobenzyl)-pyridine (NBP) and thiol-species. No NBP-alkylation was observed with 2,2-DCVC corresponding to its low cytotoxicity and mutagenicity. The lower activity of GSH-conjugation of TCE by human liver fractions, in combination with the lower fraction of potential nephrotoxic and mutagenic 1,2-DCVG-isomers, suggest that humans are at much lower risk for TCE-associated nephrotoxic effects than rats.
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Affiliation(s)
- Liliana Capinha
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, the Netherlands
| | - Paul Jennings
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, the Netherlands
| | - Jan N M Commandeur
- Division of Molecular Toxicology, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty of Sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ, Amsterdam, the Netherlands.
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DeSesso JM, Coder PS, York RG, Budinsky RA, Pottenger LH, Sen S, Lucarell JM, Bevan C, Bus JS. Trichloroethylene in drinking water throughout gestation did not produce congenital heart defects in Sprague Dawley rats. Birth Defects Res 2019; 111:1217-1233. [PMID: 31197966 PMCID: PMC7432160 DOI: 10.1002/bdr2.1531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 04/23/2019] [Accepted: 05/09/2019] [Indexed: 02/05/2023]
Abstract
BACKGROUND Trichloroethylene (TCE) was negative for developmental toxicity after inhalation and oral gavage exposure of pregnant rats but fetal cardiac defects were reported following drinking water exposure throughout gestation. Because of the deficiencies in this latter study, we performed another drinking water study to evaluate whether TCE causes heart defects. METHODS Groups of 25 mated Sprague Dawley rats consumed water containing 0, 0.25, 1.5, 500, or 1,000 ppm TCE from gestational day 1-21. TCE concentrations were measured at daily formulation, when placed into water bottles each day and when water bottles were removed from cages. Four additional mated rats per group were used for plasma measurements. At termination, fetal hearts were carefully dissected fresh and examined. RESULTS All TCE concentrations were >90% of target when initially placed in water bottles and when bottles were placed on cages. All dams survived with no clinical signs. Rats in the two higher dose groups consumed less water/day than other groups but showed no changes in maternal or fetal weights. The only fetal cardiac observation was small (<1 mm) membranous ventricular septal defect occurring in all treated and water control groups; incidences were within the range of published findings for naive animals. TCE was not detected in maternal blood, but systemic exposure was confirmed by detecting its primary oxidative metabolite, trichloroacetic acid, although only at levels above the quantitation limit in the two higher dose groups. CONCLUSIONS Ingesting TCE in drinking water ≤1,000 ppm throughout gestation does not cause cardiac defects in rat offspring.
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Affiliation(s)
- John M. DeSesso
- ExponentAlexandriaVirginia
- Georgetown University School of MedicineWashingtonDistrict of Columbia
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Khan NA, Johnson MD, Kubicki JD, Holguin FO, Dungan B, Carroll KC. Cyclodextrin-enhanced 1,4-dioxane treatment kinetics with TCE and 1,1,1-TCA using aqueous ozone. Chemosphere 2019; 219:335-344. [PMID: 30551099 DOI: 10.1016/j.chemosphere.2018.11.200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 06/09/2023]
Abstract
Enhanced reactivity of aqueous ozone (O3) with hydroxypropyl-β-cyclodextrin (HPβCD) and its impact on relative reactivity of O3 with contaminants were evaluated herein. Oxidation kinetics of 1,4-dioxane, trichloroethylene (TCE), and 1,1,1-trichloroethane (TCA) using O3 in single and multiple contaminant systems, with and without HPβCD, were quantified. 1,4-Dioxane decay rate constants for O3 in the presence of HPβCD increased compared to those without HPβCD. Density functional theory molecular modeling confirmed that formation of ternary complexes with HPβCD, O3, and contaminant increased reactivity by increasing reactant proximity and through additional reactivity within the HPβCD cavity. In the presence of chlorinated co-contaminants, the oxidation rate constant of 1,4-dioxane was enhanced. Use of HPβCD enabled O3 reactivity within the HPβCD cavity and enhanced 1,4-dioxane treatment rates without inhibition in the presence of TCE, TCA, and radical scavengers including NaCl and bicarbonate. Micro-environmental chemistry within HPβCD inclusion cavities mediated contaminant oxidation reactions with increased reaction specificity.
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Affiliation(s)
- Naima A Khan
- Water Science and Management Program, New Mexico State University, MSC 3Q P.O. Box 30003, Las Cruces, NM 88003, USA; Plant & Environmental Science, New Mexico State University, MSC 3Q P.O. Box 30003, Las Cruces, NM 88003, USA
| | - Michael D Johnson
- Department of Chemistry and Biochemistry, New Mexico State University, MSC 3C P.O. Box 30001, Las Cruces, NM 88003, USA
| | - James D Kubicki
- Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968-0555, USA
| | - F Omar Holguin
- Plant & Environmental Science, New Mexico State University, MSC 3Q P.O. Box 30003, Las Cruces, NM 88003, USA
| | - Barry Dungan
- Plant & Environmental Science, New Mexico State University, MSC 3Q P.O. Box 30003, Las Cruces, NM 88003, USA
| | - Kenneth C Carroll
- Water Science and Management Program, New Mexico State University, MSC 3Q P.O. Box 30003, Las Cruces, NM 88003, USA; Plant & Environmental Science, New Mexico State University, MSC 3Q P.O. Box 30003, Las Cruces, NM 88003, USA.
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Wang H, Wang G, Ansari GAS, Khan MF. Trichloroethene metabolite dichloroacetyl chloride induces apoptosis and compromises phagocytosis in Kupffer Cells: Activation of inflammasome and MAPKs. PLoS One 2018; 13:e0210200. [PMID: 30596806 PMCID: PMC6312261 DOI: 10.1371/journal.pone.0210200] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 12/18/2018] [Indexed: 12/20/2022] Open
Abstract
Exposure to trichloroethene (TCE), an occupational and ubiquitous environmental contaminant, is associated with the development of several autoimmune diseases, including autoimmune hepatitis (AIH). However, mechanisms contributing to TCE-mediated AIH are not known. Earlier, we have shown that dichloroacetyl chloride (DCAC), one of the reactive metabolites of TCE with strong acylating capability, can elicit an autoimmune response at much lower dose than TCE in female MRL+/+ mice. Furthermore, Kupffer cells (KCs), the liver resident macrophages, are crucial for hepatic homeostasis, but can also participate in the immunopathogenesis of AIH. However, contribution of KCs in TCE-mediated AIH and the underlying mechanisms are not understood. We hypothesized that increased apoptosis and delayed clearance of apoptotic bodies, due to compromised KC function, will result in the breakdown of self-tolerance, autoimmunity, and ultimately AIH. Therefore, using an in vitro model of immortalized mouse KCs, we investigated the contribution of DCAC in TCE-mediated AIH. KCs were treated with different concentrations of DCAC and apoptosis was measured by Annexin V and PI staining. Also, the impact of DCAC on phagocytic potential of KCs was evaluated. Furthermore, markers of inflammasome (NLRP3 and caspase1) were analyzed by real-time PCR and Western blot analysis. DCAC treatment resulted in significantly increased early and late-stage apoptosis, accompanied with inflammasome activation (NLRP3 increases). DCAC treatment resulted in decreased phagocytic function of KCs in a dose-dependent manner, with reduced MFG-E8 levels (phagocytotic function). Furthermore, DCAC exposure led to induction of phos-ERK and phos-AKT signaling. These findings suggest that DCAC induces apoptosis and inflammasome activation, while compromising the phagocytic function of KCs. Our data support that increased apoptosis and impaired KC function by DCAC could be contributory to TCE-mediated AIH.
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Affiliation(s)
- Hui Wang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas
| | - Gangduo Wang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas
| | | | - M. Firoze Khan
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas
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Ren X, Huang X, Yang X, Liu Y, Liu W, Huang H, Wu D, Zou F, Liu J. SET mediates TCE-induced liver cell apoptosis through dephosphorylation and upregulation of nucleolin. Oncotarget 2017; 8:40958-40966. [PMID: 28402964 PMCID: PMC5522280 DOI: 10.18632/oncotarget.16785] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 02/12/2017] [Indexed: 01/21/2023] Open
Abstract
Trichloroethylene (TCE) is an occupational and environmental chemical that can cause severe hepatotoxicity. While our previous studies showed that the phosphatase inhibitor SET is a key mediator of TCE-induced liver cell apoptosis, the molecular mechanisms remain elusive. Using quantitative phosphoproteomic analysis, we report here that nucleolin is a SET-regulated phosphoprotein in human liver HL-7702 cells. Functional analysis suggested that SET promoted dephosphorylation of nucleolin, decreased its binding to its transcriptional activator, c-myc, and upregulated nucleolin expression in TCE-treated cells. Importantly, TCE-induced hepatocyte apoptosis was significantly attenuated when nucleolin was downregulated with specific siRNAs. These findings indicate that TCE may induce hepatocyte apoptosis via SET-mediated dephosphorylation and overexpression of nucleolin.
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Affiliation(s)
- Xiaohu Ren
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
- School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Xinfeng Huang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Xifei Yang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Yungang Liu
- School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Wei Liu
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Haiyan Huang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Desheng Wu
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Fei Zou
- School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Jianjun Liu
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
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Doğan-Subaşi E, Bastiaens L, Leys N, Boon N, Dejonghe W. Quantitative and functional dynamics of Dehalococcoides spp. and its tceA and vcrA genes under TCE exposure. Biodegradation 2015; 25:493-504. [PMID: 25025097 DOI: 10.1007/s10532-013-9676-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This study aimed at monitoring the dynamics of phylogenetic and catabolic genes of a dechlorinating enrichment culture before, during, and after complete dechlorination of chlorinated compounds. More specifically, the effect of 40 μM trichloroethene (TCE) and 5.6 mM lactate on the gene abundance and activity of an enrichment culture was investigated for 40 days. Although tceA and vcrA gene copy numbers were relatively stable in DNA extracts over time, tceA and vcrA mRNA abundances were upregulated from undetectable levels to 2.96 × and 6.33 × 10⁴ transcripts/mL, respectively, only after exposure to TCE and lactate. While tceA gene transcripts decreased over time with TCE dechlorination, the vcrA gene was expressed steadily even when the concentration of vinyl chloride was at undetectable levels. In addition, ratios between catabolic and phylogenetic genes indicated that tceA and vcrA gene carrying organisms dechlorinated TCE and its produced daughter products, while vcrA gene was mainly responsible for the dechlorination of the lower VC concentrations in a later stage of degradation.
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Abstract
Trichloroethylene (TCE), widely used as an organic solvent in the industry, is a common contaminant in air, soil, and water. Chronic TCE exposure induced hepatocellular carcinoma in mice, and occupational exposure in humans was suggested to be associated with liver cancer. To understand the role of non-genotoxic mechanism(s) for TCE action, we examined the gene expression and DNA methylation changes in the liver of B6C3F1 mice orally administered with TCE (0, 100, 500 and 1000 mg/kg b.w. per day) for 5 days. After 5 days TCE treatment at a dose level of 1000 mg/kg b.w., a total of 431 differentially expressed genes were identified in mouse liver by microarray, of which 291 were up-regulated and 140 down-regulated. The expression changed genes were involved in key signal pathways including PPAR, proliferation, apoptosis and homologous recombination. Notably, the expression level of a number of vital genes involved in the regulation of DNA methylation, such as Utrf1, Tet2, DNMT1, DNMT3a and DNMT3b, were dysregulated. Although global DNA methylation change was not detected in the liver of mice exposed to TCE, the promoter regions of Cdkn1a and Ihh were found to be hypo- and hypermethylated respectively, which correlated negatively with their mRNA expression changes. Furthermore, the gene expression and DNA methylation changes induced by TCE were dose dependent. The overall data indicate that TCE exposure leads to aberrant DNA methylation changes, which might alter the expression of genes involved in the TCE-induced liver tumorgenesis.
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Affiliation(s)
- Yan Jiang
- Department of Physiology, School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China; Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Soochow University, Suzhou, China
| | - Jiahong Chen
- Department of Toxicology, School of Public Health, Soochow University, Suzhou, China; Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Soochow University, Suzhou, China
| | - Jian Tong
- Department of Toxicology, School of Public Health, Soochow University, Suzhou, China; Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Soochow University, Suzhou, China
| | - Tao Chen
- Department of Toxicology, School of Public Health, Soochow University, Suzhou, China; Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Soochow University, Suzhou, China
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Wang G, Wang J, Luo X, Ansari GAS, Khan MF. Nitrosative stress and nitrated proteins in trichloroethene-mediated autoimmunity. PLoS One 2014; 9:e98660. [PMID: 24892995 PMCID: PMC4043737 DOI: 10.1371/journal.pone.0098660] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 05/04/2014] [Indexed: 01/05/2023] Open
Abstract
Exposure to trichloroethene (TCE), a ubiquitous environmental contaminant, has been linked to a variety of autoimmune diseases (ADs) including SLE, scleroderma and hepatitis. Mechanisms involved in the pathogenesis of ADs are largely unknown. Earlier studies from our laboratory in MRL+/+ mice suggested the contribution of oxidative/nitrosative stress in TCE-induced autoimmunity, and N-acetylcysteine (NAC) supplementation provided protection by attenuating oxidative stress. This study was undertaken to further evaluate the contribution of nitrosative stress in TCE-mediated autoimmunity and to identify proteins susceptible to nitrosative stress. Groups of female MRL +/+ mice were given TCE, NAC or TCE + NAC for 6 weeks (TCE, 10 mmol/kg, i.p., every 4th day; NAC, ∼250 mg/kg/day via drinking water). TCE exposure led to significant increases in serum anti-nuclear and anti-histone antibodies together with significant induction of iNOS and increased formation of nitrotyrosine (NT) in sera and livers. Proteomic analysis identified 14 additional nitrated proteins in the livers of TCE-treated mice. Furthermore, TCE exposure led to decreased GSH levels and increased activation of NF-κB. Remarkably, NAC supplementation not only ameliorated TCE-induced nitrosative stress as evident from decreased iNOS, NT, nitrated proteins, NF-κB p65 activation and increased GSH levels, but also the markers of autoimmunity, as evident from decreased levels of autoantibodies in the sera. These findings provide support to the role of nitrosative stress in TCE-mediated autoimmune response and identify specific nitrated proteins which could have autoimmune potential. Attenuation of TCE-induced autoimmunity in mice by NAC provides an approach for designing therapeutic strategies.
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Affiliation(s)
- Gangduo Wang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jianling Wang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Xuemei Luo
- Biomolecular Resource Facility, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - G. A. Shakeel Ansari
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - M. Firoze Khan
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Abusoglu S, Celik HT, Tutkun E, Yilmaz H, Serdar MA, Bal CD, Yildirimkaya M, Avcikucuk M. 8-hydroxydeoxyguanosine as a useful marker for determining the severity of trichloroethylene exposure. Arch Environ Occup Health 2014; 69:180-186. [PMID: 24325749 DOI: 10.1080/19338244.2013.763761] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The aim of this study was to determine 8-hydroxydeoxyguanosine (8-OH-dG) levels in trichloroethylene (TCE)-exposed workers. Oxidative stress biomarkers and biochemical parameters were monitored among 26 TCE-exposed workers and 78 age-matched control subjects. Levels of urinary 8-OH-dG were analyzed by liquid chromatography tandem mass spectrometry. Urinary 8-OH-dG levels were significantly higher for TCE-exposed group (p < .001). Spearman's correlation test revealed positive correlations between urinary trichloroacetic acid levels and age, urinary 8-OH-dG, urinary total oxidant status, and urinary total antioxidant status (p = .042, p < .001, p < .001, and p < .001, respectively). 8-OH-dG may be a useful marker to determine the extent of TCE exposure.
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Affiliation(s)
- Sedat Abusoglu
- a Department of Biochemistry , ANKALAB Laboratory , Ankara , Turkey
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Liu J, Hu ZY, Ye QQ, Dai SH. Development of three Drosophila melanogaster strains with different sensitivity to volatile anesthetics. Chin Med J (Engl) 2009; 122:561-565. [PMID: 19323908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
BACKGROUND The mechanisms of action for volatile anesthetics remain unknown for centuries partly owing to the insufficient or ineffective research models. We designed this study to develop three strains derived from a wild-type Drosophila melanogaster with different sensitivities to volatile anesthetics, which may ultimately facilitate molecular and genetic studies of the mechanism involved. METHODS Median effective doses (ED(50)) of sevoflurane in seven-day-old virgin female and male wild-type Drosophila melanogaster were determined. The sensitive males and females of percentile 6 - 10 were cultured for breeding sensitive offspring (S(1)). So did median ones of percentile 48 - 52 for breeding median offspring (M(1)), resistant ones of percentile 91 - 95 for breeding resistant offspring (R(1)). Process was repeated through 31 generations, in the 37th generation, S(37), M(37) and R(37) were used to determine ED(50) for enflurane, isoflurane, sevoflurane, desflurane, halothane, methoxyflurane, chloroform and trichloroethylene, then ED(50) values were correlated with minimum alveolar concentration (MAC) values in human. RESULTS From a wild-type Drosophila melanogaster we were able to breed three strains with high, median and low sevoflurane requirements. The ratio of sevoflurane requirements of three strains were 1.20:1.00:0.53 for females and 1.22:1.00:0.72 for males. Strains sensitive, median and resistant to sevoflurane were also sensitive, median and resistant to other volatile anesthetics. For eight anesthetics, ED(50) values in three strains correlated directly with MAC values in human. CONCLUSIONS Three Drosophila melanogaster strains with high, median and low sensitivity to volatile anesthetics, but with same hereditary background were developed. The ED(50) are directly correlated with MAC in human for eight volatile anesthetics.
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Affiliation(s)
- Jin Liu
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
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McDowall DG, Harper AM. Blood flow and oxygen uptake of the cerebral cortex of the dog during anaesthesia with different volatile agents. Acta Neurol Scand Suppl 2009; 14:146-51. [PMID: 5214087 DOI: 10.1111/j.1600-0404.1965.tb01974.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Shen T, Zhu QX, Yang S, Ding R, Ma T, Ye LP, Wang LJ, Liang ZZ, Zhang XJ. Trichloroethylene induce nitric oxide production and nitric oxide synthase mRNA expression in cultured normal human epidermal keratinocytes. Toxicology 2007; 239:186-94. [PMID: 17719164 DOI: 10.1016/j.tox.2007.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2007] [Revised: 06/19/2007] [Accepted: 07/08/2007] [Indexed: 11/24/2022]
Abstract
Trichloroethylene (TCE), a major chemical hazard during occupational exposure, can cause obvious skin lesions, including irritant reactions and dermatitis. Nitric oxide (NO) synthesized by nitric oxide synthase (NOS) is involved in a broad array of pathogenesis of skin inflammatory and immune responses. To understand the mechanisms of TCE-induced dermatoxicity, we investigated the effects of TCE on NO production and NOS mRNA expression in cultured normal human epidermal keratinocytes (NHEK). Cells were treated with TCE (0 mM, 0.125 mM, 0.25 mM, 0.5 mM, 1.0 mM, 2.0 mM) for 4 h, and then incubated for 12 h, 24 h, 48 h and 72 h. At each given time point, NO production were evaluated indirectly by measuring nitrite plus nitrate concentration in the culture medium using Griess reaction, as well as cell viability determined by MTT test, iNOS and cNOS activities assayed with a NOS activity detecting kit. The expression of iNOS and cNOS mRNA was detected using RT-PCR. TCE decreases cell viability and enhance NO production from NHEK in concentration- and time-dependent manner. Aminoguanidine (AG), an inhibitor of NOS, can prevent NO production and cell viability decrease in NHEK by TCE induced. Change to NO production was accompanied by increased activities of both types of NOS, but the iNOS activity accounted mainly for the TCE-induced NO production. RT-PCR detection showed that NHEK expressed both iNOS and cNOS mRNA by TCE exposure. Whereas a concentration- and time-dependent up-regulation of the mRNA expression was observed for iNOS and cNOS following TCE exposure, changes to iNOS were more marked. These results suggest that TCE caused increase in NO production, attributed to activation of iNOS as well as cNOS, and expression of iNOS and cNOS mRNA. These cellular changes may contribute to the pathological and physiological features of TCE-induced erythema and skin inflammation.
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Affiliation(s)
- Tong Shen
- Institute of Dermatology, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, PR China
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Hendriksen PJM, Freidig AP, Jonker D, Thissen U, Bogaards JJP, Mumtaz MM, Groten JP, Stierum RH. Transcriptomics analysis of interactive effects of benzene, trichloroethylene and methyl mercury within binary and ternary mixtures on the liver and kidney following subchronic exposure in the rat. Toxicol Appl Pharmacol 2007; 225:171-88. [PMID: 17905399 DOI: 10.1016/j.taap.2007.08.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/02/2007] [Accepted: 08/06/2007] [Indexed: 11/27/2022]
Abstract
The present research aimed to study the interaction of three chemicals, methyl mercury, benzene and trichloroethylene, on mRNA expression alterations in rat liver and kidney measured by microarray analysis. These compounds were selected based on presumed different modes of action. The chemicals were administered daily for 14 days at the Lowest-Observed-Adverse-Effect-Level (LOAEL) or at a two- or threefold lower concentration individually or in binary or ternary mixtures. The compounds had strong antagonistic effects on each other's gene expression changes, which included several genes encoding Phase I and II metabolizing enzymes. On the other hand, the mixtures affected the expression of "novel" genes that were not or little affected by the individual compounds. The three compounds exhibited a synergistic interaction on gene expression changes at the LOAEL in the liver and both at the sub-LOAEL and LOAEL in the kidney. Many of the genes induced by mixtures but not by single compounds, such as Id2, Nr2f6, Tnfrsf1a, Ccng1, Mdm2 and Nfkb1 in the liver, are known to affect cellular proliferation, apoptosis and tissue-specific function. This indicates a shift from compound specific response on exposure to individual compounds to a more generic stress response to mixtures. Most of the effects on cell viability as concluded from transcriptomics were not detected by classical toxicological endpoints illustrating the benefit of increased sensitivity of assessing gene expression profiling. These results emphasize the benefit of applying toxicogenomics in mixture interaction studies, which yields biomarkers for joint toxicity and eventually can result in an interaction model for most known toxicants.
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Cai Z, Merly C, Thomson NR, Wilson RD, Lerner DN. Channel flow and trichloroethylene treatment in a partly iron-filled fracture: experimental and model results. J Contam Hydrol 2007; 93:284-303. [PMID: 17574704 DOI: 10.1016/j.jconhyd.2007.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 03/19/2007] [Accepted: 04/01/2007] [Indexed: 05/15/2023]
Abstract
Technical developments have now made it possible to emplace granular zero-valent iron (Fe(0)) in fractured media to create a Fe(0) fracture reactive barrier (Fe(0) FRB) for the treatment of contaminated groundwater. To evaluate this concept, we conducted a laboratory experiment in which trichloroethylene (TCE) contaminated water was flushed through a single uniform fracture created between two sandstone blocks. This fracture was partly filled with what was intended to be a uniform thickness of iron. Partial treatment of TCE by iron demonstrated that the concept of a Fe(0) FRB is practical, but was less than anticipated for an iron layer of uniform thickness. When the experiment was disassembled, evidence of discrete channelised flow was noted and attributed to imperfect placement of the iron. To evaluate the effect of the channel flow, an explicit Channel Model was developed that simplifies this complex flow regime into a conceptualised set of uniform and parallel channels. The mathematical representation of this conceptualisation directly accounts for (i) flow channels and immobile fluid arising from the non-uniform iron placement, (ii) mass transfer from the open fracture to iron and immobile fluid regions, and (iii) degradation in the iron regions. A favourable comparison between laboratory data and the results from the developed mathematical model suggests that the model is capable of representing TCE degradation in fractures with non-uniform iron placement. In order to apply this Channel Model concept to a Fe(0) FRB system, a simplified, or implicit, Lumped Channel Model was developed where the physical and chemical processes in the iron layer and immobile fluid regions are captured by a first-order lumped rate parameter. The performance of this Lumped Channel Model was compared to laboratory data, and benchmarked against the Channel Model. The advantages of the Lumped Channel Model are that the degradation of TCE in the system is represented by a first-order parameter that can be used directly in readily available numerical simulators.
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Affiliation(s)
- Zuansi Cai
- Groundwater Protection and Restoration Group, Kroto Research Institute, University of Sheffield, Sheffield S3 7HQ, UK.
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16
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Alexander DD, Kelsh MA, Mink PJ, Mandel JH, Basu R, Weingart M. A meta-analysis of occupational trichloroethylene exposure and liver cancer. Int Arch Occup Environ Health 2007; 81:127-43. [PMID: 17492303 DOI: 10.1007/s00420-007-0201-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2006] [Accepted: 04/17/2007] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Findings from epidemiologic studies of trichloroethylene (TCE) exposure and liver cancer have been inconsistent. To quantitatively evaluate this association and to examine sources of heterogeneity, we conducted a meta-analysis of occupational studies of TCE exposure and liver/biliary tract cancer. METHODS We identified 14 occupational cohort studies of TCE exposed workers and one case-control study that met our inclusion criteria. Nine studies specifically identified TCE as a workplace exposure, and were classified as Group I cohort studies. Subcohorts of workers, identified within eight of these studies as more likely exposed to TCE than the total cohort, were analyzed separately. RESULTS The combined liver/biliary cancer summary relative risk estimate (SRRE) for all studies was 1.08 (95% CI 0.91-1.29; heterogeneity (H)-P-value=0.12). For the total study populations in the Group I cohorts, the SRRE was 1.14 (95% CI 0.93-1.39; H-P-value=0.05) and for the subcohorts, the SRRE was 1.30 (95% CI 1.09-1.55). Within this subcohort analysis, the association for the European studies of workers from various industries (SRRE=1.38; based on four studies) was higher than the association for the US studies of aerospace and aircraft workers (SRRE=0.97, based on four studies). CONCLUSION Although positive associations were observed for some analyses, results were inconsistent across occupational groups (aerospace/aircraft vs. other industries combined), study location, and incidence versus mortality endpoints. In addition, exposure-response trends were not observed consistently across studies. Interpretation is also limited by the potential impact of uncontrolled confounding by other occupational or lifestyle exposures such as smoking or alcohol consumption. Given these limitations, the currently available epidemiologic data are not sufficient to support a causal relation between occupational TCE exposure and liver/biliary cancer.
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Affiliation(s)
- Dominik D Alexander
- Exponent Health Sciences, 185 Hansen Ct, Suite 100, Wood Dale, IL 60191, USA.
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17
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Wiesenhütter B, Selinski S, Golka K, Brüning T, Bolt HM. Re-assessment of the influence of polymorphisms of phase-II metabolic enzymes on renal cell cancer risk of trichloroethylene-exposed workers. Int Arch Occup Environ Health 2007; 81:247-51. [PMID: 17479278 DOI: 10.1007/s00420-007-0200-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Accepted: 04/17/2007] [Indexed: 10/23/2022]
Abstract
PROBLEM Individual differences in susceptibility to trichloroethylene-induced nephrocarcinogenicity may be conferred by genetic polymorphisms of glutathione S-transferases (GST), because enzymes of this group are pivotal for the metabolic activation of trichloroethylene. Because of a potential involvement of N-acetylation in the detoxication of reactive trichloroethylene metabolite(s) to N-acetyl-cysteine derivatives, polymorphisms of the NAT2 gene may also be relevant. METHODS The primary collective used for a re-investigation of these questions was that of a hospital-based case-control study by Brüning et al. (Am J Ind Med 43:274-285, 2003) of 134 renal cell cancer cases (20 cases exposed to trichloroethylene) and 401 matched controls. Genetic polymorphisms of GSTT1, GSTM1, GSTP1 and NAT2 were studied. Additional control collectives of non-diseased persons were used for comparison of allele frequencies. RESULTS No genetic influences on the development of renal cancer due to trichloroethylene were apparent, related to the deletion polymorphisms of GSTT1 and GSTM1, as well as to the NAT2 rapid/slow acetylator states. However, renal cell cancer cases displayed a somewhat higher proportion of the homozygous GSTP1 313A wild type (GSTP1*A), although this was not statistically significant (chi(2) test: P=0.1071, when using only the original controls of Brüning et al. (2003); P=0.0781 with inclusion of the additional controls). CONCLUSION The re-investigation does not confirm the working hypothesis of an influence of the deletion polymorphisms of the glutathione S-transferases GSTT1 and GSTM1 on renal cell cancer development due to high occupational exposures to trichloroethylene.
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Affiliation(s)
- Bernd Wiesenhütter
- Institut für Arbeitsphysiologie an der Universität Dortmund, Ardeystr. 67, 44139 Dortmund, Germany
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Lamb JC, Hentz KL. Toxicological review of male reproductive effects and trichloroethylene exposure: Assessing the relevance to human male reproductive health. Reprod Toxicol 2006; 22:557-63. [PMID: 16938429 DOI: 10.1016/j.reprotox.2006.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 06/19/2006] [Accepted: 07/05/2006] [Indexed: 11/18/2022]
Abstract
Effects of trichloroethylene (TCE) on male reproduction and fertility have been studied in mice and rats, and assessed in workers exposed to TCE. Only limited evidence exists for any male reproductive effects in rats or humans. The human studies of TCE male reproductive effects failed to provide much useful information for risk assessment. First, the TCE-specific studies are limited in group size, scope, and typically provide no data on dose, so dose-response assessment is impossible. In other studies, TCE is only one of many solvents identified in the workplace, such that the confounding exposures or lack of evidence of specific exposures make the exposure assessment useless. For TCE risk assessment, one currently must rely upon animal studies as more reliable and useful. The rat studies were generally negative, showing systemic toxicity but little or no male reproductive toxicity. The mouse studies showed various organ effects in the male reproductive system and were typically associated with increased liver weight and kidney toxicity. Enzyme induction and oxidative metabolism appear to be important in the systemic toxicity and may likewise play a role in the reproductive toxicity of TCE. Oxidative metabolites of TCE are formed in the mouse epididymis resulting in epididymal damage, and at systemically toxic high doses, TCE may adversely affect the maturation of sperm and decreasing sperm motility. Protection against systemic toxicity should also protect against adverse effects including male reproductive toxicity.
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Affiliation(s)
- James C Lamb
- The Weinberg Group Inc, Washington, DC 20036, USA.
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19
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Kim HE, Shitashiro M, Kuroda A, Takiguchi N, Ohtake H, Kato J. Identification and characterization of the chemotactic transducer in Pseudomonas aeruginosa PAO1 for positive chemotaxis to trichloroethylene. J Bacteriol 2006; 188:6700-2. [PMID: 16952963 PMCID: PMC1595487 DOI: 10.1128/jb.00584-06] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa PAO1 is repelled by trichloroethylene (TCE), and the methyl-accepting chemotaxis proteins PctA, PctB, and PctC serve as the major chemoreceptors for negative chemotaxis to TCE. In this study, we found that the pctABC triple mutant of P. aeruginosa PAO1 was attracted by TCE. Chemotaxis assays of a set of mutants containing deletions in 26 potential mcp genes revealed that mcpA (PA0180) is the chemoreceptor for positive chemotaxis to TCE. McpA also detects tetrachloroethylene and dichloroethylene isomers as attractants.
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Affiliation(s)
- Hye-Eun Kim
- Department of Molecular Biotechnology, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan
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Drake VJ, Koprowski SL, Lough J, Hu N, Smith SM. Trichloroethylene exposure during cardiac valvuloseptal morphogenesis alters cushion formation and cardiac hemodynamics in the avian embryo. Environ Health Perspect 2006; 114:842-7. [PMID: 16759982 PMCID: PMC1480523 DOI: 10.1289/ehp.8781] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
It is controversial whether trichloroethylene (TCE) is a cardiac teratogen. We exposed chick embryos to 0, 0.4, 8, or 400 ppb TCE/egg during the period of cardiac valvuloseptal morphogenesis (2-3.3 days' incubation) . Embryo survival, valvuloseptal cellularity, and cardiac hemodynamics were evaluated at times thereafter. TCE at 8 and 400 ppb/egg reduced embryo survival to day 6.25 incubation by 40-50%. At day 4.25, increased proliferation and hypercellularity were observed within the atrioventricular and outflow tract primordia after 8 and 400 ppb TCE. Doppler ultrasound revealed that the dorsal aortic and atrioventricular blood flows were reduced by 23% and 30%, respectively, after exposure to 8 ppb TCE. Equimolar trichloroacetic acid (TCA) was more potent than TCE with respect to increasing mortality and causing valvuloseptal hypercellularity. These results independently confirm that TCE disrupts cardiac development of the chick embryo and identifies valvuloseptal development as a period of sensitivity. The hypercellular valvuloseptal profile is consistent with valvuloseptal heart defects associated with TCE exposure. This is the first report that TCA is a cardioteratogen for the chick and the first report that TCE exposure depresses cardiac function. Valvuloseptal hypercellularity may narrow the cardiac orifices, which reduces blood flow through the heart, thereby compromising cardiac output and contributing to increased mortality. The altered valvuloseptal formation and reduced hemodynamics seen here are consistent with such an outcome. Notably, these effects were observed at a TCE exposure (8 ppb) that is only slightly higher than the U.S. Environmental Protection Agency maximum containment level for drinking water (5 ppb) .
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Affiliation(s)
- Victoria J Drake
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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21
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Baynes RE, Yeatts JL, Brooks JD, Riviere JE. Pre-treatment effects of trichloroethylene on the dermal absorption of the biocide, triazine. Toxicol Lett 2005; 159:252-60. [PMID: 15979828 DOI: 10.1016/j.toxlet.2005.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 05/23/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
Triazine is often added to cutting-fluid formulations in the metal-machining industry as a preservative. Trichloroethylene (TCE) is a solvent used for cleaning the cutting fluid or oil from the metal product. The purpose of this study was to examine the effect of TCE on the dermal absorption of triazine in an in vitro flow-through diffusion cell system. Skin sections were dosed topically with aqueous mixtures containing mineral oil or polyethylene glycol (PEG) spiked with (14)C-triazine. Some skin sections were simultaneously exposed to TCE while other skin sections were pre-treated with TCE daily for 4 days in vivo and then exposed to these mixtures in vitro. TCE pre-treatment almost doubled triazine permeability, but this pre-treatment had no effect on triazine diffusivity. The pre-treatment effects of TCE on triazine permeability appear to be more important in PEG-based mixtures than in the mineral oil-based mixtures. Simultaneous single exposure to TCE had little or no effect on triazine absorption. TCE absorption was significantly less than triazine absorption; however, cutting fluid additives had a more significant effect on TCE absorption than on triazine absorption. In summary, this study demonstrated that TCE pre-treatment can significantly alter the dermal permeability to triazine, and workers who are chronically exposed to this or similar cleansers may be at increased risk of absorbing related skin irritants.
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Affiliation(s)
- Ronald E Baynes
- Center for Chemical Toxicology Research and Pharmacokinetics (CCTRP), College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.
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22
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Huang HY, Liu JJ, Zhuang ZX, Li XY, Xu XY, Wei QZ, Yang XH. [Two-dimensional electrophoresis and mass spectrometry analysis on effects of trichloroethylene on protein of L-02 liver cells]. Zhonghua Yu Fang Yi Xue Za Zhi 2005; 39:175-8. [PMID: 15938849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
OBJECTIVE To study the effects of trichloroethylene (TCE) on the protein in L-02 cells in vitro. METHODS Thiazolyl blue and Trypan blue tests were used to investigate the cytotoxicity of TCE to L-02 liver cell. The 2-D electrophoresis was used to analyse the expression of proteins in L-02 liver cells. The differentially expressed protein spots were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-TOF-MS). RESULTS When the concentration of TCE exceeded 30 micromol/L, there was distinct cytotoxicity to L-02 cell (P < 0.05). Selected 40 micromol/L to treat L-02 liver cells and analyze the differential proteome expression, the results showed that the expression level of 37 protein spots was up-regulated and 15 protein spots was down-regulated. And 15 proteins were identified by MALDI-TOF-TOF-MS. CONCLUSION TCE can change the proteome expression of L-02 liver cell. It should provide the fundamental information to identify proteins related to TCE in further study.
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Affiliation(s)
- Hai-yan Huang
- Laboratory of food and Toxicology, Shenzhen Center for Disease Control and Prevention, Shenzhen 510080, China
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23
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Totonidis S. A role for trichloroethylene in developing nation anaesthesia. Kathmandu Univ Med J (KUMJ) 2005; 3:181-90. [PMID: 16415619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Affiliation(s)
- S Totonidis
- Royal Hobart Hospital, Hobart, Tasmania, Australia
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Trichloroethylene. Rep Carcinog 2004; 11:III261-3. [PMID: 21089976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Juliastuti SR, Baeyens J, Creemers C, Bixio D, Lodewyckx E. The inhibitory effects of heavy metals and organic compounds on the net maximum specific growth rate of the autotrophic biomass in activated sludge. J Hazard Mater 2003; 100:271-283. [PMID: 12835028 DOI: 10.1016/s0304-3894(03)00116-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A respirometry technique can be applied as an effective method to determine the net maximum specific growth rate of autotrophic biomass under both normal conditions and when inhibition occurs. The net maximum specific growth rate of uninhibited autotrophic biomass, expressed as (mu(A)-b(A)), is approximately 0.8 per day [Proceeding of the International Congress on CHISA, Prague, 2002, p. 1]. Several heavy metals and organic compounds have inhibitory effects. Copper (Cu(2+)) has stronger inhibitory effects than zinc (Zn(2+)), and inhibits the nitrification process by 50% at 0.08 mg/l [(mu(A)-b(A)) = 0.4 per day], while the same concentration of Zn(2+) establishes 12% inhibition only [(mu(A)-b(A)) = 0.75 per day]. Inhibition with Cu(2+) starts at concentrations above 0.05 mg/l, while this is above 0.3mg/l for Zn(2+). The inhibition of the nitrification process is complete at 1.2mg/l for both Cu(2+) and Zn(2+). Among the selected organic compounds tested n the experiments, the degree of inhibition decreases as follow: chlorobenzene>trichloroethylene (TCE)>phenol>ethylbenzene. Chlorobenzene already inhibits the autotrophic biomass at 0.25 mg/l. The nitrification process is totally inhibited by adding 0.75 mg/l of chlorobenzene. TCE has a less inhibitory effect on the nitrification process and 50% inhibition is noticed at 0.75 mg/l TCE. The nitrification process is totally inhibited at 1mg/l TCE. Phenol inhibits the nitrification for 50% at 3 mg/l. The inhibitory effect of phenol is almost constant in the range 4-10 mg/l and complete inhibition is reached at 50 mg/l. The inhibitory effect of ethylbenzene is 50% at 8 mg/l and the autotrophic biomass is totally inhibited at 50 mg/l. Experimental findings are compared with literature data, which generally and significantly overestimate the inhibition threshold concentrations.
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Affiliation(s)
- S R Juliastuti
- Department of Chemical Engineering, Katholieke Universiteit Leuven, de Croylaan 46, B-3001 Heverlee, Leuven, Belgium.
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Ou J, Ou Z, McCarver DG, Hines RN, Oldham KT, Ackerman AW, Pritchard KA. Trichloroethylene decreases heat shock protein 90 interactions with endothelial nitric oxide synthase: implications for endothelial cell proliferation. Toxicol Sci 2003; 73:90-7. [PMID: 12657742 DOI: 10.1093/toxsci/kfg062] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Trichloroetheylene (TRI) is an environmental pollutant that has been linked to congenital heart defects (CHD). Endothelial nitric oxide synthase (eNOS) generation of nitric oxide (NO) plays an important role in endothelial cell proliferation, which is considered essential for normal blood vessel growth and development. We hypothesized that TRI alters the balance of NO and superoxide anion (O2-) to impair endothelial cell proliferation. Proliferating endothelial cells were pretreated with TRI (5 microM) and then stimulated with the calcium ionophore, A23187 (5 microM), to determine changes in endothelial cell and eNOS function with respect to NO and O2- generation. Immunoblots of eNOS, phospho-eNOS at serine 1179 (S1179), and the levels of associated heat shock protein 90 (hsp90) were used to define the activation state of eNOS. The effects of TRI (0.05-100 microM) on vascular endothelial growth factor (VEGF, 0.58 nM) induced endothelial cell proliferation were determined from cell counts. TRI decreased A23187-stimulated nitrite + nitrate production from 1.99 +/- 0.90 to 0.89 +/- 0.51 pmol/mg protein (p < 0.05; n = 6). In controls, Lomega-nitroargininemethylester (L-NAME) increased A23187-stimulated O2- production from 0.130 +/- 0.089 to 0.214 +/- 0.071 nmol/min/mg protein (p < 0.05; n = 5). In TRI-treated cultures, however, L-NAME decreased A23187-stimulated O2- production from 0.399 +/- 0.121 to 0.199 +/- 0.055 nmol/min/mg protein (p < 0.05; n = 5). TRI decreased hsp90 associated with eNOS by 46.7% and inhibited VEGF-stimulated endothelial cell proliferation by 12 to 35%. These data show that TRI alters hsp90 interactions with eNOS and induces eNOS to shift from NO to O2- generation. Our findings provide new insight into how TRI alters endothelial and eNOS function to impair VEGF-stimulated endothelial proliferation. Such changes in endothelial function may play an important role in the development of congenital heart defects.
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Affiliation(s)
- Jingsong Ou
- Department of Surgery, Division of Pediatric Surgery, Cardiovascular Center, Milwaukee, Wisconsin 53226, USA.
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Abstract
In Ralstonia pickettii PKO1, a denitrifying toluene oxidizer that carries a toluene-3-monooxygenase (T3MO) pathway, the biodegradation of toluene and trichloroethylene (TCE) by the organism is induced by TCE at high concentrations. In this study, the effect of TCE preexposure was studied in the context of bacterial protective response to TCE-mediated toxicity in this organism. The results of TCE degradation experiments showed that cells induced by TCE at 110 mg/liter were more tolerant to TCE-mediated stress than were those induced by TCE at lower concentrations, indicating an ability of PKO1 to adapt to TCE-mediated stress. To characterize the bacterial protective response to TCE-mediated stress, the effect of TCE itself (solvent stress) was isolated from TCE degradation-dependent stress (toxic intermediate stress) in the subsequent chlorinated ethylene toxicity assays with both nondegradable tetrachloroethylene and degradable TCE. The results of the toxicity assays showed that TCE preexposure led to an increase in tolerance to TCE degradation-dependent stress rather than to solvent stress. The possibility that such tolerance was selected by TCE degradation-dependent stress during TCE preexposure was ruled out because a similar extent of tolerance was observed in cells that were induced by toluene, whose metabolism does not produce any toxic products. These findings suggest that the adaptation of TCE-induced cells to TCE degradation-dependent stress was caused by the combined effects of solvent stress response and T3MO pathway expression.
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Affiliation(s)
- Joonhong Park
- Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824-1325, USA
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Plewka A, Zielińska-Psuja B, Kowalówka-Zawieja J, Nowaczyk-Dura G, Plewka D, Wiaderkiewicz A, Kamiński M, Orłowski J. Influence of acetaminophen and trichloroethylene on liver cytochrome P450-dependent monooxygenase system. Acta Biochim Pol 2002; 47:1129-36. [PMID: 11996102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The aim of the study was to evaluate the effect of acetaminophen (APAP) and/or trichloroethylene (TRI) on the liver cytochrome P450-dependent monooxygenase system, CYP2E1 and CYP1A2 (two important P450 isoforms), and liver glutathione (GSH) content in rats. Rats were given three different doses of APAP (250, 500 and 1000 mg/kg b...) and then the above-mentioned parameters were measured for 48 h. The lowest APAP dose produced small changes in the cytochrome P450 content of liver. At 500 mg/kg APAP increased the cytochrome P450 content to 230% of the control. The inductive effect was seen at 1000 mg/kg dose but at 24 h and later. NADPH-cytochrome P450 reductase activity was the highest after the lowest dose of APAP, while after the highest dose it was equal to the control value. TRI increased both the cytochrome P450 content and the NADPH-cytochrome P450 reductase activity. When TRI was combined with APAP, both these parameters increased in the first hours of observation, but they returned to the control values at 24 h. When APAP was given at 250 mg/kg, GSH levels decreased to 55% of the control at 8 h and returned to the control values at 24 h. The higher doses of APAP decreased GSH levels more than the lowest dose, but after 24 h GSH levels did not differ from those of the control. When TRI was given at 250 mg/kg, the GSH levels decreased to 68% of the control at 2 h and then they increased gradually and tended to exceed the control values at 48 h. The effect of TRI combined with APAP on the level of GSH was virtually the same as that of APAP alone given at 500 mg/kg.
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Affiliation(s)
- A Plewka
- Department of Histology and Embryology, Silesian School of Medicine, Katowice-Ligota, Poland.
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Yeager CM, Bottomley PJ, Arp DJ. Requirement of DNA repair mechanisms for survival of Burkholderia cepacia G4 upon degradation of trichloroethylene. Appl Environ Microbiol 2001; 67:5384-91. [PMID: 11722883 PMCID: PMC93320 DOI: 10.1128/aem.67.12.5384-5391.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A Tn5-based mutagenesis strategy was used to generate a collection of trichloroethylene (TCE)-sensitive (TCS) mutants in order to identify repair systems or protective mechanisms that shield Burkholderia cepacia G4 from the toxic effects associated with TCE oxidation. Single Tn5 insertion sites were mapped within open reading frames putatively encoding enzymes involved in DNA repair (UvrB, RuvB, RecA, and RecG) in 7 of the 11 TCS strains obtained (4 of the TCS strains had a single Tn5 insertion within a uvrB homolog). The data revealed that the uvrB-disrupted strains were exceptionally susceptible to killing by TCE oxidation, followed by the recA strain, while the ruvB and recG strains were just slightly more sensitive to TCE than the wild type. The uvrB and recA strains were also extremely sensitive to UV light and, to a lesser extent, to exposure to mitomycin C and H(2)O(2). The data from this study establishes that there is a link between DNA repair and the ability of B. cepacia G4 cells to survive following TCE transformation. A possible role for nucleotide excision repair and recombination repair activities in TCE-damaged cells is discussed.
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Affiliation(s)
- C M Yeager
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon 97331-2902, USA
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Wang JL, Chen WL, Tsai SY, Sung PY, Huang RN. An in vitro model for evaluation of vaporous toxicity of trichloroethylene and tetrachloroethylene to CHO-K1 cells. Chem Biol Interact 2001; 137:139-54. [PMID: 11551530 DOI: 10.1016/s0009-2797(01)00226-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Toxicokinetics of trichloroethylene (TCE) and tetrachloroethylene (PER) in culture medium and their toxicity to CHO-K1 cells were investigated by employing an in vitro vapor exposure system. Cells were cultured in a 60 mm petri dish with a 25 mm glass dish glued in the central area. TCE or PER was added to the central glass dish so that it would evaporate and dissolve in the surrounding medium in which cells were growing. The results showed that the concentration of TCE or PER in medium increased significantly within 20 min and then decreased very rapidly with time. After a 24 h incubation, the residual of TCE or PER in the medium was very low, but was displayed in a dose-dependent manner. Treatment of cells with either TCE or PER resulted in a dose- and time-dependent inhibition of cell growth. A significantly increase in the frequency of micronuclei (MN) was also observed with either TCE or PER treatment. Low doses of TCE (5-20 microl) or PER (1-5 microl) significantly enhanced the intracellular glutathione (GSH) level. However, the level of GSH rapidly decreased with higher doses of TCE (40-80 microl) or PER (10-20 microl). Depletion of cellular GSH showed no effect on the sensitivity of cells to TCE or PER treatment. GSH-conjugation has been proposed as an activation mechanism to account for the nephrotoxicity of TCE and PER, however the toxicity of TCE and PER to CHO-K1 cells is probably mediated through a distinct mechanism.
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Affiliation(s)
- J L Wang
- Department of Chemistry, National Central University, Chung-li, 32054, Taoyuan, Taiwan, ROC
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31
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Abstract
The effects of a common industrial solvent, trichloroethylene (TCE), which was once used as an anesthetic agent but its in vivo mechanism is still unknown, on convulsant-induced seizures in mice were examined. Pretreatment with TCE (250-2000 mg/kg, i.p.) significantly increased pentylenetetrazol (PTZ)-, picrotoxin (PIC)-, bicuculline (BIC)-, strychnine (STY)-, 4-aminopyridine (4-AP)- and N-methyl-D-aspartate (NMDA)-induced convulsion thresholds and lethal doses. However, the increase in convulsion thresholds and lethal doses was much greater for GABAergic antagonists (PIC, BIC, and PTZ) than non-GABAergic convulsants (STY, 4AP, and NMDA) following 2000 mg/kg TCE administration. Pre-treatment of mice with disulfiram (an inhibitor of CYP 4502E1) but not 4-methyl pyrazole (an inhibitor of alcohol dehydrogenase) significantly prolonged the time required for TCE (5000 mg/kg, i.p.) to induce the loss of righting reflex. These results suggest that acute exposure to TCE differentially alters the susceptibility to chemically induced convulsions in mice. The anticonvulsive effect of TCE may be predominantly mediated by GABA(A) receptors. In addition, TCE appears to exert a direct anesthetic effect.
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Affiliation(s)
- C L Shih
- Department of Pharmacology, Tzu Chi University, 701 Section 3, Chung Yang Road, Hualien 970, Taiwan
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32
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Khan MF, Wu X, Ansari GA. Anti-malondialdehyde antibodies in MRL+/+ mice treated with trichloroethene and dichloroacetyl chloride: possible role of lipid peroxidation in autoimmunity. Toxicol Appl Pharmacol 2001; 170:88-92. [PMID: 11162772 DOI: 10.1006/taap.2000.9086] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Trichloroethene (TCE) and one of its metabolites dichloroacetyl chloride (DCAC) are known to induce/accelerate autoimmune (AI) response in MRL+/+ mice as evident from anti-nuclear, anti-ssDNA, anti-cardiolipin, and DCAC-specific antibodies in the serum (Khan et al., Toxicol. Appl. Pharmacol. 134, 155-160, 1995). In the present study, we measured anti-malondialdehyde antibodies (AMDA) in the serum of TCE- or DCAC-treated mice in order to understand the contribution of lipid peroxidation to this AI response. Female MRL+/+ mice (5 weeks old) received ip injections of 10 mmol/kg TCE or 0.2 mmol/kg of DCAC in corn oil (100 microl) every 4(th) day for 6 weeks, while controls received an equal volume of vehicle only, and AMDA was measured in the sera of these animals by an ELISA established in our laboratory. While TCE treatment caused only marginal induction of AMDA, DCAC treatment elicited a significant AMDA response. Furthermore, a time-response study of DCAC (0.2 mmol/kg, every 4(th) day, for 2, 4, 6, or 8 weeks) showed an induction of AMDA (3/4) after 4 weeks of treatment, which was even greater at both 6 and 8 weeks of DCAC treatment (5/5). These findings were further substantiated by the presence of AMDA in systemic lupus erythematosus-prone MRL-lpr/lpr mice as early as 6 weeks of age. Presence of AMDA, as observed in this study, not only indicates increased lipid peroxidation (oxidative stress), but also suggests a putative role of oxidative stress in inflammatory autoimmune diseases.
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Affiliation(s)
- M F Khan
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
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Abstract
It is often necessary for chemical risk assessment to determine a quantitative relationship between the internal dose of a chemical and its biological effect. The tool best suited for this purpose is a biologically based pharmacodynamic (BBPD) model. Such a BBPD model was developed previously (10) to simulate chemically induced lipid peroxidation, and it was experimentally calibrated in precision-cut mouse liver slices in vitro. The BBPD model simulated formation of lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) over time and was originally calibrated with different concentrations of tert-butyl hydroperoxide and bromotrichloromethane. The objective of the present work is to refine this BBPD model so it can describe the kinetics and the dose response of lipid peroxidation induced by a weakly pro-oxidant chemical, trichloroethylene (TCE). The chemical-dependent model parameters were optimized to reflect the chemistry of TCE. Two basic algorithms, linear and square root, for the description of stoichiometric free radical production from TCE were tested. Predictions with the square root algorithm fit the experimental data employing TBARS as an end point better than those by the linear algorithm. The calibrated BBPD model will be used to support our future mathematical description of TCE pharmacodynamics in vivo.
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Affiliation(s)
- J Z Byczkowski
- ManTech Environmental Technology Inc., Dayton, OH 45437, USA.
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Boyes WK, Bushnell PJ, Crofton KM, Evans M, Simmons JE. Neurotoxic and pharmacokinetic responses to trichloroethylene as a function of exposure scenario. Environ Health Perspect 2000; 108 Suppl 2:317-22. [PMID: 10807561 PMCID: PMC1637762 DOI: 10.1289/ehp.00108s2317] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Strategies are needed for assessing the risks of exposures to airborne toxicants that vary over concentrations and durations. The goal of this project was to describe the relationship between the concentration and duration of exposure to inhaled trichloroethylene (TCE), a representative volatile organic chemical, tissue dose as predicted by a physiologically based pharmacokinetic model, and neurotoxicity. Three measures of neurotoxicity were studied: hearing loss, signal detection behavior, and visual function. The null hypothesis was that exposure scenarios having an equivalent product of concentration and duration would produce equal toxic effects, according to the classic linear form of Haber's Rule ((italic)C(/italic) times t = k), where C represents the concentration, t, the time (duration) of exposure, and k, a constant toxic effect. All experiments used adult male, Long-Evans rats. Acute and repeated exposure to TCE increased hearing thresholds, and acute exposure to TCE impaired signal detection behavior and visual function. Examination of all three measures of neurotoxicity showed that if Haber's Rule were used to predict outcomes across exposure durations, the risk would be overestimated when extrapolating from shorter to longer duration exposures, and underestimated when extrapolating from longer to shorter duration exposures. For the acute effects of TCE on behavior and visual function, the estimated concentration of TCE in blood at the time of testing correlated well with outcomes, whereas cumulative exposure, measured as the area under the blood TCE concentration curve, did not. We conclude that models incorporating dosimetry can account for differing exposure scenarios and will therefore improve risk assessments over models considering only parameters of external exposure.
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Affiliation(s)
- W K Boyes
- Neurotoxicology Division, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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35
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Abstract
Trichloroethylene is an industrial solvent and has become a major environmental contaminant. Autoimmune-prone MRL +/+ mice were treated for up to 22 weeks with trichloroethylene in the drinking water (0, 2.5, and 5.0 mg/mL) in order to study the immunoregulatory effects of this environmental toxicant. After only 4 weeks of treatment, trichloroethylene was shown to promote the expansion of CD4+ T cells that expressed a memory/activation phenotype (i.e., CD44hi CD45RBlo) and secreted high levels of IFN-gamma, but not IL-4. In addition, trichloroethylene treatment accelerated the development of an autoimmune response in the MRL +/+ mice as evidenced by an earlier appearance of antinuclear antibodies and increased levels of total IgG2a. MRL +/+ mice treated with trichloroethylene for 22 weeks also contained antibodies specific for trichloroethylene adducts, suggesting the activation of trichloroethylene-specific T cells. The results suggest that trichloroethylene can stimulate antigen nonspecific as well as specific T cells that are capable of promoting autoimmunity in genetically predisposed individuals.
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Affiliation(s)
- K M Gilbert
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock 72205, USA
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Soni MG, Ramaiah SK, Mumtaz MM, Clewell H, Mehendale HM. Toxicant-inflicted injury and stimulated tissue repair are opposing toxicodynamic forces in predictive toxicology. Regul Toxicol Pharmacol 1999; 29:165-74. [PMID: 10341147 DOI: 10.1006/rtph.1998.1280] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
These studies were designed to investigate the dose response for liver injury and tissue repair induced by exposure to four structurally and mechanistically dissimilar hepatotoxicants, individually and as mixtures. The objective was to illuminate the impact of the extent and timeliness of tissue repair on the ultimate outcome of toxicity. Dose-response relationships for trichloroethylene (TCE), allyl alcohol (AA), thioacetamide (TA), and chloroform alone or as mixtures were studied. Male Sprague-Dawley rats (200-250 g) received a single intraperitoneal injection of individual toxicants as well as mixtures of these toxicants. Liver injury was monitored by plasma enzyme (ALT and SDH) levels and histopathology. Tissue regeneration was measured by [3H]thymidine incorporation into hepatic nuclear DNA. Individually, TCE, TA, and AA administration, over a 10- to 12-fold dose range, revealed a dose-related increase in injury as well as tissue repair up to a threshold dose. Beyond this threshold, tissue repair was delayed and attenuated, and liver injury progressed. Mixtures of the four chemicals at the higher doses used in individual dose-response studies resulted in 100% mortality. Hence, mixtures at the lower two doses were selected for further study. Additional lower doses were also included to better understand the dose-response relationship of mixtures. Results of these studies support the observations of individual chemicals. Higher and sustained repair was observed at low dose levels. These studies show that the extent of injury at early time points correlates well with the maximal stimulation of the opposing response of tissue repair. It appears that the toxicity of the mixture employed in these studies is roughly additive and correlates well with tissue repair response. These initial studies suggest that a biologically based mathematical model can be constructed and tested to extrapolate the outcome of toxicity from a given dose of individual compounds as well as their mixtures, where the responses measured are injury on the one hand and compensatory tissue repair on the other.
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Affiliation(s)
- M G Soni
- College of Pharmacy and Health Sciences, Northeast Louisiana University, Monroe, Louisiana 71209-0470, USA
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37
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Abstract
Peroxisome proliferators are a group of structurally diverse chemicals that cause the proliferation of peroxisomes in rodents. The purpose of this investigation was to test the hypothesis that the shared effect of these compounds on peroxisome proliferation is mediated through a common inhibitory effect on mitochondrial bioenergetics. Freshly isolated rat liver mitochondria were energized with succinate. The effect of the chemicals on mitochondrial bioenergetics was analyzed by monitoring calcium-induced changes in membrane potential and swelling, as well as changes in mitochondrial respiration. Mitochondrial membrane potential was measured with a TPP(+)-sensitive electrode, and swelling was recorded spectrophotometrically. Mitochondrial oxygen uptake was monitored with a Clark-type oxygen electrode. Gemfibrozil and WY-14,643 induced the mitochondrial permeability transition as characterized by calcium-induced swelling and depolarization of membrane potential, both of which were inhibited by cyclosporine A. Fenofibrate, clofibrate, ciprofibrate and diethylhexyl phthalate, on the other hand, caused a direct dose-dependent depolarization of mitochondrial membrane potential. However, the mechanism of membrane depolarization varied among the test chemicals. Bezafibrate and trichloroethylene elicited no effect on succinate-supported mitochondrial bioenergetics. The results of this investigation demonstrate that although most, but not all, peroxisome proliferators interfere with mitochondrial bioenergetics, the specific biomolecular mechanism differs among the individual compounds.
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Affiliation(s)
- S Zhou
- Department of Biochemistry and Molecular Biology, University of Minnesota School of Medicine, Duluth 55812, USA
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Uchiyama H, Shinohara Y, Tomioka N, Kusakabe I. Induction and enhancement of stress proteins in a trichloroethylene-degrading methanotrophic bacterium, Methylocystis sp. M. FEMS Microbiol Lett 1999; 170:125-30. [PMID: 10094607 DOI: 10.1111/j.1574-6968.1999.tb13364.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The responses of the trichloroethylene-degrading bacterium Methylocystis sp. M to six different water-pollutants, carbon starvation, and temperature-shock (heat and cold) were examined using 2-dimensional gel electrophoresis. Twenty-eight polypeptides were induced, and these stress-induced proteins were classified into three groups. Some of the chemically induced proteins were the same as those induced by carbon starvation and temperature-shock. Two of the polypeptides were induced by trichloroethylene. Trichloroethylene-stress protein synthesis required 1-2 h at a concentration of trichloroethylene that had no effect on growth. Furthermore, 25 stress-enhanced polypeptides were observed, and one of these was enhanced by trichloroethylene. Based on these results, we discuss applications of chemical-stress induction of proteins to establish effective bioremediation and bioassay by methanotrophs.
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Affiliation(s)
- H Uchiyama
- National Institute for Environmental Studies, Ibaraki, Japan.
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39
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Douglas GR, Gingerich JD, Soper LM, Potvin M, Bjarnason S. Evidence for the lack of base-change and small-deletion mutation induction by trichloroethylene in lacZ transgenic mice. Environ Mol Mutagen 1999; 34:190-194. [PMID: 10529743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Trichloroethylene (TCE) is a widely used industrial solvent employed mainly for degreasing and cold-cleaning metal parts. It is also used for dry cleaning, and in the production of a number of chemical products. It has been shown to induce liver and lung tumors in rodents, and have a variety of positive and negative results using in vitro and in vivo mutagenicity tests. In order to assist in the interpretation of the mechanism of carcinogenicity, TCE was tested for the ability to induce gene mutations and small deletions using the lacZ transgenic mouse model (MutaMouse). Male and female animals were exposed by inhalation to 0, 203, 1153, and 3141 ppm TCE, 6 h per day for 12 days. 14 and 60 days following the last exposure, animals were sacrificed and the mutation frequency in bone marrow, kidney, spleen, liver, lung, and testicular germ cells determined. The results of this study indicate that TCE did not induce base-change or small-deletion mutations as detected in this assay in any of the tissues examined. Environ. Mol. Mutagen. 34: 190-194, 1999. Published 1999 Wiley-Liss, Inc.
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Affiliation(s)
- G R Douglas
- Mutagenesis Section, Environmental Health Directorate, Health Canada, Ottawa, Ontario, K1A 0L2 Canada
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40
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Shingleton JT, Applegate BM, Nagel AC, Bienkowski PR, Sayler GS. Induction of the tod operon by trichloroethylene in Pseudomonas putida TVA8. Appl Environ Microbiol 1998; 64:5049-52. [PMID: 9835608 PMCID: PMC90968 DOI: 10.1128/aem.64.12.5049-5052.1998] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bioluminescence, mRNA levels, and toluene degradation rates in Pseudomonas putida TVA8 were measured as a function of various concentrations of toluene and trichloroethylene (TCE). TVA8 showed an increasing bioluminescence response to increasing TCE and toluene concentrations. Compared to uninduced TVA8 cultures, todC1 mRNA levels increased 11-fold for TCE-treated cultures and 13-fold for toluene-treated cultures. Compared to uninduced P. putida F1 cultures, todC1 mRNA levels increased 4.4-fold for TCE-induced cultures and 4.9-fold for toluene-induced cultures. Initial toluene degradation rates were linearly correlated with specific bioluminescence in TVA8 cultures.
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Affiliation(s)
- J T Shingleton
- Center for Environmental Biotechnology, The University of Tennessee, Knoxville, Tennessee 37996, USA
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41
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Lilly PD, Thornton-Manning JR, Gargas ML, Clewell HJ, Andersen ME. Kinetic characterization of CYP2E1 inhibition in vivo and in vitro by the chloroethylenes. Arch Toxicol 1998; 72:609-21. [PMID: 9851676 DOI: 10.1007/s002040050551] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Trans- and cis-1,2-dichloroethylene (DCE) isomers inhibit their own metabolism in vivo by inactivation of the metabolizing enzyme, presumably the cytochrome P450 isoform, CYP2E1. In this study, we examined cytochrome P450 isoform-specific inhibition by three chloroethylenes, cis-DCE, trans-DCE, and trichloroethylene (TCE), and evaluated several kinetic mechanisms of enzyme inhibition with physiological models of inhibition. Trans-DCE was more potent than cis-DCE, and both were much more effective than TCE in inhibiting CYP2E1. The kinetics of in vitro loss of p-nitrophenol hydroxylase (pNP-OH) activity (a marker of CYP2E1) in microsomal incubations and of the in vivo gas uptake results were most consistent with a mechanism in which inhibition of the metabolizing enzyme (CYP2E1) was presumed to be related to interaction of a reactive DCE metabolite with remaining substrate-bound, active CYP2E1. The kinetics of inhibition by TCE, a weak inhibitor in vitro, were very different from that of the dichloroethylenes. With TCE, parent compound concentrations influenced enzyme loss. Trans-DCE was a more potent inhibitor of CYP2E1 than cis-DCE based on both in vivo and in vitro studies. Quantitative differences in the inhibitory properties of the 1,2-DCE isomers may be due to the different stability of epoxides formed from bioactivation by CYP2E1. Epoxide intermediates of DCE metabolism, reacting by water addition, would yield dialdehyde, a potent cross-linking reagent.
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Affiliation(s)
- P D Lilly
- Curriculum in Toxicology, University of North Carolina-Chapel Hill, USA
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Abstract
The use of in vitro systems in the assessment of xenobiotic metabolism has distinct advantages and disadvantages. While isolated hepatocytes and microsomes prepared from human liver may be used to generate data for comparisons among species and in vitro systems, such comparisons are generally performed on the basis of microsomal protein or million (viable) hepatocytes. Recently, in vitro data have been investigated for their value as quantitative predictors of in vivo metabolic capacity. Because of the existence of large amounts of trichloroethylene (TRI) data in the human, we have examined the metabolism of TRI as a case study in the development of a method to compare metabolism across species using in vitro systems and for extrapolation of metabolic rates from in vitro to in vivo. TRI is well metabolized by human hepatocytes in culture with a K(m) of 266 +/- 202 ppm (mean +/- SD) in headspace and a Vmax of 16.1 +/- 12.9 nmol/h/10(6) viable hepatocytes. We determined that human liver contains approximately 116 x 10(6) hepatocytes and 20.8 mg microsomal protein/g, based on DNA recovery and glucose-6-phosphatase activity, respectively. Thus, the microsomal protein content of hepatocytes is 179 micrograms microsomal protein/10(6) isolated hepatocytes. The microsomal apparent Vmax value of 1589 pmol/min/mg microsomal protein extrapolates to 17.07 nmol/h/10(6) hepatocytes. The combination of protein recovery and metabolic rate predicted a Vmax of approximately 1400 nmol/h/g human liver, which, when extrapolated and incorporated into an existing physiologically based pharmacokinetic (PBPK) model for TRI, slightly underpredicted TRI metabolism in the intact human. The quantitation, extrapolation, and inclusion of extrahepatic and cytochrome P450 (CYP)-independent TRI metabolism may increase the predictive value of this approach.
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Affiliation(s)
- J C Lipscomb
- U.S. Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7400, USA
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43
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Abstract
The biodegradation and toxicity of tetrachlorethylene (C2Cl4) and trichloroethylene (C2HCl3) were studied with different anaerobic enrichment cultures using the following electron donors: acetate, propionate, butyrate, methanol, formate and hydrogen. All of them sustained dechlorination except propionate, for which C2Cl4 biodegradation rates were not significant. The best results were obtained with butyrate. Hydrogen appeared to be a relevant electron donor for dechlorination with the present cultures. In the presence of specific inhibitors such as bromoethanesulphonate or molybdate, a slight inhibition of dechlorination was observed. According to dechlorination kinetics, Monod-type behaviour was observed up to 120 microM C2Cl4 or 200 microM C2HCl3 with Ks values around 7 microM for both compounds. Dechlorination was partially inhibited at higher concentrations. In contrast, methanogens, or at least methane production, were more sensitive to the presence of chlorinated ethylenes and inhibitions of methanogenesis was observed to different extents over all the C2Cl4/C2HCl3 concentration range tested, even at the lowest concentrations.
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Affiliation(s)
- C Kennes
- University of La Coruña, Department of Fundamental and Industrial Chemistry, Faculty of Sciences, Spain
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Lange CC, Wackett LP, Minton KW, Daly MJ. Engineering a recombinant Deinococcus radiodurans for organopollutant degradation in radioactive mixed waste environments. Nat Biotechnol 1998; 16:929-33. [PMID: 9788348 DOI: 10.1038/nbt1098-929] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Thousands of waste sites around the world contain mixtures of toxic chlorinated solvents, hydrocarbon solvents, and radionuclides. Because of the inherent danger and expense of cleaning up such wastes by physicochemical methods, other methods are being pursued for cleanup of those sites. One alternative is to engineer radiation-resistant microbes that degrade or transform such wastes to less hazardous mixtures. We describe the construction and characterization of recombinant Deinococcus radiodurans, the most radiation-resistant organism known, expressing toluene dioxygenase (TDO). Cloning of the tod genes (which encode the multicomponent TDO) into the chromosome of this bacterium imparted to the strain the ability to oxidize toluene, chlorobenzene, 3,4-dichloro-1-butene, and indole. The recombinant strain was capable of growth and functional synthesis of TDO in the highly irradiating environment (60 Gy/h) of a 137Cs irradiator, where 5x10(8)cells/ml degraded 125 nmol/ml of chlorobenzene in 150 min. D. radiodurans strains were also tolerant to the solvent effects of toluene and trichloroethylene at levels exceeding those of many radioactive waste sites. These data support the prospective use of engineered D. radiodurans for bioremediation of mixed wastes containing both radionuclides and organic solvents.
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Affiliation(s)
- C C Lange
- Department of Biochemistry, Molecular Biology and Biophysics, Biological Process Technology Institute, University of Minnesota, St. Paul 55108, USA
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45
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Channel SR, Latendresse JR, Kidney JK, Grabau JH, Lane JW, Steel-Goodwin L, Gothaus MC. A subchronic exposure to trichloroethylene causes lipid peroxidation and hepatocellular proliferation in male B6C3F1 mouse liver. Toxicol Sci 1998; 43:145-54. [PMID: 9710956 DOI: 10.1006/toxs.1998.2456] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The common groundwater contaminant trichloroethylene (TCE), when given by oral gavage, can produce free radical species during metabolism. Furthermore, TCE end-stage metabolites, trichloroacetic acid and dichloroacetic acid, cause lipid peroxidation in mouse liver. The time courses of lipid peroxidation, free radical generation, and 8-hydroxydeoxyguanosine (8OHdG) formation were used to assess the level of oxidative stress in the liver of B6C3F1 mice dosed orally once daily, 5 days a week for 8 weeks at 0, 400, 800, and 1200 mg/kg TCE in corn oil. Peroxisomal proliferation, cell proliferation, and apoptosis were evaluated at selected times during the study. Lipid peroxidation, as measured by thiobarbituric acid-reactive substances (TBARS), was significantly elevated at the two highest dose levels of TCE on days 6 through 14 of the study. 8OHdG levels were statistically significant in the 1200 mg/kg/day group on days 2, 3, 10, 28, 49, and 56 only. The highest measured free radical load, 307% of oil control, occurred at day 6. A significant increase in cell and peroxisomal proliferation was observed during the same time period in the 1200 mg/kg/day group. Necrosis or an increase in apoptosis was not observed at any dose. The temporal relationship between oxidative stress and cellular response of proliferation, both of which occur and resolve within the same relative time period, suggests that TCE-induced mitogenesis may result from alteration in the liver microenvironment which offers a selective advantage for certain hepatocyte subpopulations.
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Affiliation(s)
- S R Channel
- Toxicology Division, Armstrong Laboratory, Toledo, Ohio, USA
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Abstract
Trichloroethylene (TRI) is an industrial solvent with a history of use in anesthesia, and is a common groundwater contaminant. Cytochrome P450 (CYP)-dependent metabolism of TRI produces chloral hydrate (CH) and is rate limiting in the ultimate production of trichloro- and/or dichloroacetic acid from TRI. Exposure of rodents to TRI results in lung and liver tumors (mice) and nephrotoxicity (rats). The toxicity is exacerbated by pretreatment of mice with CYP inducers. We report significant variability in TRI metabolism in a sample of 23 human hepatic microsomal samples and demonstrate the dependence of TRI metabolism on CYP2E1. K(m) values in this limited sample population are not normally distributed. We have correlated microsomal CH formation with the activity toward routine CYP2E1 substrates and with immunologically detectable CYP2E1 protein. Further, TRI metabolism in microsomes from lymphoblastoid cell lines expressing CYP2E1, CYP1A1, CYP1A2, or CYP3A4 indicated minimal involvement of the latter forms, with CYP2E1 catalyzing more than 60% of total microsomal TRI metabolism. These results indicate that humans are not uniform in their capacity for CYP-dependent metabolism of TRI and increased CYP2E1 activity may increase susceptibility to TRI-induced toxicity in the human.
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Affiliation(s)
- J C Lipscomb
- United States Air Force, Armstrong Laboratory, Toxicology Division, OL-AL HSC/OET, Wright-Patterson Air Force Base, Ohio 45433-7400, USA.
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47
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Abstract
1. To investigate the effects of trichloroethylene on cytochrome P4502E1 (CYP2E1), an isozyme responsible for its metabolic activation, mice were treated with trichloroethylene and Western blot staining with both anti-dichloroacetyl and anti-CYP2E1 antisera detected a comigrating 50 kDa protein band. There was a dose-dependent increase in the intensity of the 50 kDa protein adduct stained immunochemically with anti-dichloroacetyl. 2. CYP2E1 enzyme activity was decreased from control levels in a dose-dependent manner in mice treated with 250-500 mg/kg TRI. 3. Microsomal incubations with trichloroethylene resulted in covalent binding to several proteins including a 50 kDa adduct, which is in contrast with the selective binding to the 50 kDa protein observed in vivo. 4. CYP2E1 enzyme activity levels were significantly decreased following microsomal incubation with NADPH and trichloroethylene, and additionally there was a time- and NADPH-dependent decrease in enzyme activity indicating that trichloroethylene is a mechanism-based inhibitor of CYP2E1.
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Affiliation(s)
- N C Halmes
- Division of Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205, USA
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48
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el-Masri HA, Constan AA, Ramsdell HS, Yang RS. Physiologically based pharmacodynamic modeling of an interaction threshold between trichloroethylene and 1,1-dichloroethylene in Fischer 344 rats. Toxicol Appl Pharmacol 1996; 141:124-32. [PMID: 8917684 DOI: 10.1006/taap.1996.0268] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Physiologically based pharmacokinetic modeling (PBPK) and gas uptake experiments have been used by researchers to demonstrate the competitive inhibition mechanism between trichloroethylene (TCE) and 1,1-dichloroethylene (DCE). Expanding on their work, we showed that this pharmacokinetic interaction was absent at levels of 100 ppm or less of either chemical in gas uptake systems. In this study, we further illustrate the presence of such an interaction threshold at the pharmacodynamic level by examining the interaction effect of either chemical on the other's ability to bind and deplete hepatic glutathione (GSH) in Fischer 344 rats. However, at this end point, the pharmacodynamic interaction is complicated by the ability of the liver to resynthesize GSH in response to its depletion. To quantitatively resolve the interaction effects on GSH content from the resynthesis effects, physiologically based pharmacodynamic (PBPD) modeling is applied. Initially, the PBPD model description of hepatic GSH kinetics was calibrated against previously published data and by gas uptake experiments conducted in our laboratory. Then, the model was used to determine the duration of the gas uptake exposure experiments by identifying the critical time point at which hepatic GSH is at a minimum in response to both chemicals. Subsequently, gas uptake experiments were designed following the PBPK/PD model predictions. In these model-directed experiments, DCE was the only chemical capable of significantly depleting hepatic GSH. The application of TCE to the rats at concentrations higher than 100 ppm obstructed the ability of DCE to deplete hepatic GSH. Since the metabolites of DCE bind to hepatic GSH, this obstruction signaled the presence of metabolic inhibition by TCE. However, TCE, at concentrations less than 100 ppm, was not effective in inhibiting DCE from significantly depleting hepatic GSH. The same observations were made when the ability of DCE to cause hepatic injury, as measured by aspartate aminotransferase serum activity, was assessed. Both conclusions validated the previous findings of the presence of the interaction threshold at the pharmacokinetic level.
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Affiliation(s)
- H A el-Masri
- Laboratory of Computational Biology and Risk Analysis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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49
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Abstract
1. The present study was undertaken to determine whether various anaesthetic agents affect canine gastric acid secretion independently of other experimental variables. 2. Acid secretory output was determined in dogs with chronic fistulae, by administering sedating doses of anaesthetics commonly used for studying gastric secretory mechanisms in laboratory animals. 3. The anaesthetic agents inhibited gastric acid secretion. As the inhibitory effect of the mixture of anaesthetics was pronounced, an attempt was made to study the effect of each individual anaesthetic agent separately. 4. Acetopromazine was given to sedate dogs. Although it has a long duration of action, it only had a transient inhibitory action on gastric acid secretion of 15-30 min duration. Moreover the drug reduced pentagastrin-stimulated secretion, but had no effect on histamine-stimulated secretion. 5. Thiopentone sodium given with acetopromazine produced a mild inhibitory effect on histamine-stimulated secretion for 45 min, but produced a more pronounced and sustained inhibitory effect on pentagastrin-stimulated secretion. 6. Trilene significantly inhibited both histamine- and pentagastrin-stimulated secretion. The effect on the latter was more pronounced and sustained. 7. Trauma had no significant effect on histamine-stimulated secretion, but showed a slight inhibitory effect on pentagastrin-stimulated secretion. 8. Experiments to study gastric secretory mechanisms and antisecretory drugs should take account of the potential inhibitory effects of anaesthetics. Where possible, studies in conscious dogs with gastric fistulae are preferable to experiments on anaesthetized animals.
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Affiliation(s)
- S M Bastaki
- Department of Pharmacology, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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50
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Abstract
A review of the literature indicates that some compounds which produce hepatic peroxisome proliferation in rats also appear to produce Leydig cell adenomas, and some also affect the serum concentrations of testosterone and estradiol. Previous studies with the peroxisome proliferator ammonium perfluorooctanoate showed a direct effect on Leydig cells to alter steroidogenesis. It was therefore proposed that peroxisome proliferators in general may directly affect Leydig cell function to produce Leydig cell tumors by some undetermined mechanism. The present study investigated whether the following peroxisome proliferators directly affect Leydig cell function in vitro: 2,4-dichlorophenoxyacetic acid, ammonium perfluorooctanoate, acetylsalicylic acid, clofibric acid, ciprofibrate, gemfibrozil, tiadenol, tibric acid, trichloroacetic acid, trichloroethylene, and Wyeth 14,643. Leydig cells, isolated from adult Crl:CDBR rats (12-16 weeks old), were treated with peroxisome proliferator for 21 hr and the medium was assayed for estradiol. The function of the treated Leydig cell was evaluated by measuring the release of testosterone in response to human chorionic gonadotropin (hCG). In general, the peroxisome proliferators reduced the hCG-stimulated release of testosterone and either reduced or had no effect on the baseline release of testosterone. Of the 11 peroxisome proliferators, 8 increased the release of estradiol from Leydig cells treated for 1 day. Two more compounds were found to increase estradiol production when the treatment period was extended to 2 days. These effects were seen at noncytotoxic doses and at concentrations similar to those achieved in rat serum in dietary studies. The results suggest that peroxisome proliferators, as a class of compounds, directly modify the steroidogenic function of Leydig cells in vitro. Some of these compounds are known to produce Leydig cell tumors in rats, but this association has yet to be established for other peroxisome proliferators. This suggests that compounds which directly affect Leydig cell function in vitro may also induce Leydig cell tumors in vivo. Further investigations are necessary to address the mechanism for the in vitro effects on Leydig cells and to clarify the apparent relationship between peroxisome proliferator-induced changes in Leydig cell function and the development of Leydig cell tumors.
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Affiliation(s)
- R C Liu
- Haskell Laboratory for Toxicology and Industrial Medicine, E. I. du Pont de Nemours and Company, Newark, Delaware 19714-0050, USA
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