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1. |
Rapid Communication METABOLISM OF STYRENE BY HUMAN LIVER AND LUNG |
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Journal of Toxicology and Environmental Health, Part A,
Volume 59,
Issue 8,
2000,
Page 591-595
Gary P. Carlson, Nancy A. Mantick, Mark W. Powley,
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摘要:
In mice, styrene is pneumotoxic, and there is some evidence of tumorigenicity. This toxicity is thought to be related to its bioactivation to styrene oxide in lung. To determine if human tissues have this capacity, the metabolism of styrene to styrene oxide was measured in human liver and lung microsomal preparations. Hepatic microsomes metabolized styrene to styrene oxide, but lung microsomes had essentially no activity. However, microsomes from both tissues metabolized benzene to phenol. The data suggest that human lung has low styrene metabolizing activity and may be much less of a target organ than in mouse.
ISSN:1528-7394
DOI:10.1080/009841000156600
出版商:Informa UK Ltd
年代:2000
数据来源: Taylor
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2. |
BEHAVIOR OF FREE-RANGING AND CAPTIVE AMERICAN KESTRELS UNDER ELECTROMAGNETIC FIELDS |
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Journal of Toxicology and Environmental Health, Part A,
Volume 59,
Issue 8,
2000,
Page 597-603
Kimberly J. Fernie, Nancy J. Leonard, David M. Bird,
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摘要:
Wild birds, particularly raptors, commonly use electrical transmission structures for nesting, perching, hunting, and roosting. Consequently, birds are exposed to electromagnetic fields (EMFs). The amount of time that wild reproducing American kestrels (Falco sparverius) were exposed to EMFs was determined, and the effects of EMFs on the behavior of captive reproducing kestrels were examined. Wild kestrels were exposed to EMFs for 25% to 75% of the observed time. On a 24-h basis, estimated EMF exposure of wild kestrels ranged from 71% during courtship, to 90% during incubation, similar to that experienced by captive kestrels (88% of a 24-h period). Additionally, captive kestrels were exposed to EMF levels experienced by wild kestrels nesting under 735-kV power lines. Captive EMF females were more active, more alert, and perched on the pen roof more frequently than control females during courtship. EMF females preened and rested less often during brood rearing. EMF male kestrels were more active than control males during courtship, and more alert during incubation. Increased activity of kestrels during courtship may be linked to changes in corticosterone, but likely not melatonin. Observed behavioral changes were unlikely to directly result in the better growth of nestlings and fledging success, or poorer hatching success, of the EMF group, as previously reported. Behavioral changes of captive EMF kestrels may be observed in wild kestrels.
ISSN:1528-7394
DOI:10.1080/009841000156619
出版商:Informa UK Ltd
年代:2000
数据来源: Taylor
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3. |
METHODOLOGY FOR CHARACTERIZING DISTRIBUTIONS OF INCREMENTAL BODY BURDENS OF 2,3,7,8-TCDD AND DDE FROM BREAST MILK IN NORTH AMERICAN NURSING INFANTS |
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Journal of Toxicology and Environmental Health, Part A,
Volume 59,
Issue 8,
2000,
Page 605-639
Judy S. LaKind, Cheston M. Berlin, Colin N. Park, Daniel Q. Naiman, Nicholas J. Gudka,
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摘要:
A clear picture of ranges of doses of breast-milk contaminants experienced by nursing infants in North America has not yet been described, resulting in a significant gap in our understanding of potential health risks to infants from those contaminants. While point estimates of incremental dose have appeared in the published literature, these do not account for the wide variability in exposures experienced by nursing infants. This research expands on the current state of understanding of breast-milk contaminant exposure by characterizing distributions, rather than point estimates, of dose. Distributions of milk intake by nursing infants were characterized to exam ine intake of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and dichlorodiphenyl dichloroethane (DDE). The results indicate that, despite the uncertainties inherent in modeling incremental body burdens of chemicals from nursing, estimating incremental infant body burdens of lipophilic chemicals from breastfeeding using point estimates may result in overly conservative estimates of the contribution of breastfeeding to long-term body burdens of those chemicals in children. To develop reliable estimates of incremental body burden from nursing, depuration via lactation and half-life in the infant should be considered. Further, incremental infant body burdens of lipophilic chemicals increase rapidly at the start of lactation, but decrease after approximately 5 to 6 mo; by 2 yr postpartum, incremental body burdens have decreased substantially. Given the benefits afforded to infants who breastfeed, and because breastfeeding does not necessarily lead to significantly increased long-term body burdens in infants, breastfeeding should be encouraged and promoted.
ISSN:1528-7394
DOI:10.1080/009841000156628
出版商:Informa UK Ltd
年代:2000
数据来源: Taylor
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4. |
EFFECTS OF TRIMETAZIDINE ON OXIDANT/ANTIOXIDANT STATUS IN TRINITROBENZENESULFONIC ACID-INDUCED CHRONIC COLITIS |
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Journal of Toxicology and Environmental Health, Part A,
Volume 59,
Issue 8,
2000,
Page 641-652
Ferhan Girgin, Onder Karaoglu, Muhan Erkus, Sevgi Tuzun, Omer Ozutemiz, Cigdem Dincer, Yucel Batur, Tijen Tanyalcin,
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摘要:
Trimetazidine (TMZ), an anti-ischemic agent with proposed antioxidant properties, was used in a chronic colitis model in order to evaluate its effectiveness as a therapeutic agent in chronic colitis. Treatment of male Swiss Albino rats with ethanol (50%) and trinitrobenzenesulfonic acid (TNBS) (30 mg/kg) produced colitis as evidenced by histopathologic damage and inflammatory alterations, lipid peroxidation [increased malondialdehyde (MDA) levels], and enhanced neutrophil infiltration [increased myeloperoxidase (MPO) activity] without marked change in glutathione status. Administration of TMZ (5 mg/kg) to TNBS-treated rats failed to affect the TNBS-induced changes in histopathology and MPO activities. Unexpectedly, intrarectal (ir) administration of TMZ significantly elevated colonic MDA levels to a greater extent than TNBS alone. Intraperitoneal (ip) TMZ treatment seemed to increase total glutathione (tGSH), GSH, and GSH/GSSG values. In conclusion, our results demonstrated that (a) ir administration of ethanol and TNBS is an effective way of inducing a chronic colitis model, (b) inflammation and lipid peroxidation augment tissue damage in the chronic colitis model, (c) ip TMZ treatment significantly inhibits MDA production in the chronic colitis model, (d) TMZ treatment is more effective via the ip compared to ir route, and (e) TMZ seems to show its antioxidant effect via preserving the tissue's GSH/GSSG ratios.
ISSN:1528-7394
DOI:10.1080/009841000156637
出版商:Informa UK Ltd
年代:2000
数据来源: Taylor
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5. |
DETERMINATION OF BIOKINETIC INTERACTIONS IN CHEMICAL MIXTURES USING REAL-TIME BREATH ANALYSIS AND PHYSIOLOGICALLY BASED PHARMACOKINETIC MODELING |
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Journal of Toxicology and Environmental Health, Part A,
Volume 59,
Issue 8,
2000,
Page 653-670
Karla D. Thrall, Torka S. Poet,
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摘要:
Regulatory agencies are challenged to conduct risk assessments on chemical mixtures without full information on toxicological interactions that may occur at real-world, lowdose exposure levels. The present study was undertaken to investigate the pharmacokinetic impact of low-dose coexposures to toluene and trichloroethylene in vivo in male F344 rats using a real-time breath analysis system coupled with physiologically based pharmacokinetic (PBPK) modeling. Rats were exposed to compounds alone or as a binary mixture, at low (5 to 25 mg/kg) or high (240 to 800 mg/kg) dose levels. Exhaled breath from the exposed animals was monitored for the parent compounds and a PBPK model was used to analyze the data. At low doses, exhaled breath kinetics from the binary mixture exposure compared with those obtained during single exposures, thus indicating that no metabolic interaction occurred with these low doses. In contract, at higher doses the binary PBPK model simulating independent metabolism was found to underpredict the exhaled breath concentration, suggesting an inhibition of metabolism. Therefore the binary mixture PBPK model was used to compare the measured exhaled breath levels from high- and low-dose exposures with the predicted levels under various metabolic interaction simulations (competitive, noncompetitive, or uncompetitive inhibition). Of these simulations, the optimized competitive metabolic interaction description yielded a Kivalue closest to the Kmof the inhibitor solvent, indicating that competitive inhibition is the most plausible type of metabolic interaction between these two solvents.
ISSN:1528-7394
DOI:10.1080/009841000156646
出版商:Informa UK Ltd
年代:2000
数据来源: Taylor
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