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  Subjects -> ENVIRONMENTAL STUDIES (Total: 768 journals)
    - ENVIRONMENTAL STUDIES (704 journals)
    - POLLUTION (22 journals)
    - TOXICOLOGY AND ENVIRONMENTAL SAFETY (33 journals)
    - WASTE MANAGEMENT (9 journals)

ENVIRONMENTAL STUDIES (704 journals)            First | 1 2 3 4 5 6 7 8     

International innovation. Environment     Open Access  
International Journal of Acarology     Hybrid Journal   (Followers: 1)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 2)
International Journal of African Renaissance Studies - Multi-, Inter- and Transdisciplinarity     Hybrid Journal   (Followers: 2)
International Journal of Agricultural and Environmental Information Systems     Full-text available via subscription   (Followers: 1)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 1)
International Journal of Applied Psychoanalytic Studies     Hybrid Journal   (Followers: 2)
International Journal of Chinese Culture and Management     Hybrid Journal   (Followers: 1)
International Journal of Corrosion     Open Access   (Followers: 10)
International Journal of Critical Infrastructures     Hybrid Journal   (Followers: 3)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 5)
International Journal of Disaster Risk Science     Open Access   (Followers: 8)
International Journal of Ecological Economics and Statistics     Full-text available via subscription   (Followers: 1)
International Journal of Ecology     Open Access   (Followers: 8)
International Journal of Ecology & Development     Full-text available via subscription   (Followers: 1)
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 2)
International Journal of Environment     Open Access   (Followers: 3)
International Journal of Environment and Health     Hybrid Journal   (Followers: 7)
International Journal of Environment and Pollution     Hybrid Journal   (Followers: 6)
International Journal of Environment and Sustainable Development     Hybrid Journal   (Followers: 13)
International Journal of Environment and Waste Management     Hybrid Journal   (Followers: 6)
International Journal of Environment, Workplace and Employment     Hybrid Journal   (Followers: 3)
International Journal of Environmental Engineering     Hybrid Journal   (Followers: 5)
International Journal of Environmental Health Engineering     Open Access  
International Journal of Environmental Health Research     Hybrid Journal   (Followers: 3)
International Journal of Environmental Policy and Decision Making     Hybrid Journal   (Followers: 10)
International Journal of Environmental Protection     Open Access   (Followers: 12)
International Journal of Environmental Research and Public Health     Open Access   (Followers: 14)
International Journal of Environmental Science and Technology     Hybrid Journal   (Followers: 4)
International Journal of Environmental Studies     Hybrid Journal   (Followers: 11)
International Journal of Exergy     Hybrid Journal   (Followers: 3)
International Journal of Forest, Soil and Erosion     Open Access   (Followers: 3)
International Journal of Global Environmental Issues     Hybrid Journal   (Followers: 4)
International Journal of Global Warming     Hybrid Journal   (Followers: 5)
International Journal of Greenhouse Gas Control     Partially Free   (Followers: 5)
International Journal of Health Planning and Management     Hybrid Journal   (Followers: 6)
International Journal of Hygiene and Environmental Health     Hybrid Journal   (Followers: 5)
International Journal of Logistics Research and Applications : A Leading Journal of Supply Chain Management     Hybrid Journal   (Followers: 9)
International Journal of Philosophical Studies     Hybrid Journal   (Followers: 3)
International Journal of Phytoremediation     Hybrid Journal   (Followers: 1)
International Journal of Process Systems Engineering     Hybrid Journal   (Followers: 1)
International Journal of Recycling of Organic Waste in Agriculture     Open Access   (Followers: 1)
International Journal of Regulation and Governance     Hybrid Journal   (Followers: 2)
International Journal of Reliability and Safety     Hybrid Journal   (Followers: 5)
International Journal of Renewable Energy Development     Open Access   (Followers: 5)
International Journal of Social Sciences and Management     Open Access  
International Journal of Soil, Sediment and Water     Open Access   (Followers: 8)
International Journal of Stress Management     Full-text available via subscription   (Followers: 8)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 7)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Materials and Structural Systems     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Society     Hybrid Journal   (Followers: 7)
International Journal of Testing     Hybrid Journal   (Followers: 1)
International Journal of the Commons     Open Access   (Followers: 2)
International Journal of Toxicology     Hybrid Journal   (Followers: 6)
International Journal of Water Resources and Environmental Engineering     Open Access  
International Review of Environmental and Resource Economics     Full-text available via subscription  
International Studies in the Philosophy of Science     Hybrid Journal   (Followers: 9)
Interventions : International Journal of Postcolonial Studies     Hybrid Journal   (Followers: 5)
IOP Conference Series: Earth and Environmental Science     Open Access   (Followers: 7)
Iranian Journal of Environmental Health Science & Engineering     Open Access   (Followers: 1)
Iranian Studies     Hybrid Journal   (Followers: 8)
Irish Educational Studies     Hybrid Journal   (Followers: 1)
Irish Journal of Earth Sciences     Full-text available via subscription  
Irish Political Studies     Hybrid Journal   (Followers: 7)
ISLE: Interdisciplinary Studies in Literature and Environment     Hybrid Journal   (Followers: 2)
Isotopes in Environmental and Health Studies     Hybrid Journal   (Followers: 2)
Israel Studies     Full-text available via subscription   (Followers: 5)
ISRN Ecology     Open Access  
ISRN Environmental Chemistry     Open Access  
Italian Studies     Hybrid Journal   (Followers: 6)
Jahangirnagar University Environmental Bulletin     Open Access  
Journal of Bioremediation & Biodegradation     Open Access   (Followers: 2)
Journal of Earth Science & Climatic Change     Open Access   (Followers: 8)
Journal of Petroleum & Environmental Biotechnology     Open Access   (Followers: 2)
Journal of Advances in Environmental Health Research     Open Access  
Journal of Agricultural and Environmental Ethics     Hybrid Journal   (Followers: 6)
Journal of Agricultural Biotechnology and Sustainable Development     Open Access  
Journal of Agriculture and Environment     Open Access  
Journal of Agriculture and Environment for International Development     Open Access   (Followers: 6)
Journal of Agrobiology     Open Access   (Followers: 2)
Journal of Applied Ecology     Hybrid Journal   (Followers: 134)
Journal of Applied Meteorology and Climatology     Full-text available via subscription   (Followers: 7)
Journal of Applied Psychoanalytic Studies     Hybrid Journal   (Followers: 1)
Journal of Applied Sciences and Environmental Management     Open Access   (Followers: 1)
Journal of Applied Sciences in Environmental Sanitation     Open Access   (Followers: 5)
Journal of Applied Toxicology     Hybrid Journal   (Followers: 9)
Journal of Applied Volcanology     Open Access   (Followers: 6)
Journal of Arid Environments     Hybrid Journal   (Followers: 8)
Journal of Asian Studies     Full-text available via subscription   (Followers: 20)
Journal of Biochemical and Molecular Toxicology     Hybrid Journal   (Followers: 5)
Journal of Black Studies     Hybrid Journal   (Followers: 3)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 1)
Journal of Chemical Health and Safety     Hybrid Journal   (Followers: 2)
Journal of Climate     Full-text available via subscription   (Followers: 21)
Journal of Coastal Research     Full-text available via subscription   (Followers: 11)
Journal of Contaminant Hydrology     Hybrid Journal   (Followers: 9)
Journal of Contemporary European Studies     Hybrid Journal   (Followers: 3)
Journal of East African Natural History     Full-text available via subscription   (Followers: 5)
Journal of Ecology     Hybrid Journal   (Followers: 34)

  First | 1 2 3 4 5 6 7 8     

Journal Cover Journal of Applied Toxicology
   [11 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0260-437X - ISSN (Online) 1099-1263
     Published by John Wiley and Sons Homepage  [1602 journals]   [SJR: 0.689]   [H-I: 47]
  • Comparative genotoxicity of nanosilver in human liver HepG2 and colon
           Caco2 cells evaluated by fluorescent microscopy of cytochalasin
           B‐blocked micronucleus formation
    • Authors: Saura C. Sahu; Shambhu Roy, Jiwen Zheng, Jeffrey J. Yourick, Robert L. Sprando
      Abstract: As a consequence of the increased use of silver nanoparticles in food, food contact materials, dietary supplements and cosmetics to prevent fungal and bacterial growth, there is a need for validated rapid screening methods to assess the safety of nanoparticle exposure. This study evaluated two widely used in vitro cell culture models, human liver HepG2 cells and human colon Caco2 cells, as tools for assessing the potential genotoxicity of 20‐nm nanosilver. The average silver nanoparticle size as determined by transmission electron microscopy (TEM) was 20.4 nm. Dynamic light scattering (DLS) analysis showed no large agglomeration of the silver nanoparticles. The silver concentration in a 20‐nm nanosilver solution determined by the inductively coupled plasma–mass spectrometry (ICP‐MS) analysis was 0.962 mg ml−1. Analysis by ICP‐MS and TEM demonstrated the uptake of 20‐nm silver by both HepG2 and Caco2 cells. Genotoxicity was determined by the cytochalasin B‐blocked micronucleus assay with acridine orange staining and fluorescence microscopy. Concentration‐ and time‐dependent increases in the frequency of binucleated cells with micronuclei induced by the nanosilver was observed in the concentration range of 0.5 to 15 µg ml−1 in both HepG2 and Caco2 cells compared with the control. Our results indicated that HepG2 cells were more sensitive than Caco2 cells in terms of micronuclei formation induced by nanosilver exposure. In summary, the results of this study indicate that the widely used in vitro models, HepG2 and Caco2 cells in culture, represent potential screening models for prediction of genotoxicity of silver nanoparticles by in vitro micronucleus assay. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2014-06-06T09:15:06.224268-05:
      DOI: 10.1002/jat.3028
       
  • Time‐dependent bioaccumulation of distinct rod‐type TiO2
           nanoparticles: Comparison by crystalline phase
    • Authors: Eun-Jung Park; Gwang-Hee Lee, Cheolho Yoon, Min-Sung Kang, Soo Nam Kim, Myung-Haing Cho, Jae-Ho Kim, Dong-Wan Kim
      Abstract: A complete understanding of the interaction between nanoparticles and biological systems, including nanoparticle uptake and distribution and the biological responses, could guide the design of safer and more effective nanoparticles than those currently available. In this study, we compared the distribution in mice over time of two rod‐type titanium dioxide nanoparticles (TiNPs) that feature distinct phases, anatase (ATO) and brookite (BTO). Surface areas of BTO and ATO were estimated to be 102 and 268 m2 g–1, respectively, and negative charge on the surface of ATO was higher than that of BTO in deionized water. Both TiNPs were rapidly distributed into tissues after injection. At 4 weeks after injection, both TiNPs were maximally accumulated in the spleen, followed by the liver, but the total accumulation of ATO in tissues measured in this study was more than that of BTO. Moreover, the cellular antioxidant function was similar although the levels of Ti measured in tissues were distinct between the two TiNPs. Based on these results, we suggest that the fate of TiNPs in the body may differ according to the size and surface charge of the TiNPs even when their shape is the same. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-29T08:38:10.446352-05:
      DOI: 10.1002/jat.3006
       
  • Vascular endothelial growth factor mRNA levels as a biomarker for
           short‐term N‐butyl‐N‐(4‐hydroxybutyl)
           nitrosamine‐induced rat bladder carcinogenesis bioassay
    • Authors: Shin Wakui; Tomoko Mutou, Hiroyuki Takahashi, Masahiro Ikegami, Hideki Wanibuchi, Shoji Fukushima
      Abstract: Generically, carcinogenic effects of chemicals in bladder carcinogenesis are judged by induction of papillary or nodular (PN) hyperplasia in rats given N‐butyl‐N‐(4‐hydroxybutyl) nitrosamine (BBN) for 4 weeks and the test chemical for 22–28 weeks. However, upregulation of vascular endothelial growth factor (VEGF) begins early in rat BBN bladder carcinogenesis. To establish a short‐term rat bladder carcinogenic bioassay, we analyzed the correlations between VEGF, VEGF mRNA and bladder lesions inductions at 10 and 26 weeks after BBN treatment. Six‐week‐old male Wistar (slc) rats were given 0.05% BBN for 4, 10 or 26 weeks. To avoid individual rat bias, the bladders were investigated by partial cystectomy at 10 weeks and total cystectomy at 26 weeks. After induction, PN hyperplasia and carcinoma in rats increased with the length of BBN treatment and immunohistochemical VEGF expression also increased following carcinogenesis, but the immunoreactivity of individual lesions was quite variable. Moreover, induction of PN hyperplasia at 10 weeks’ BBN treatment was not significantly correlated with that at 26 weeks' treatment; thus, it was not possible to predict the carcinogenic effect due to the induction of PN hyperplasia at 26 weeks' BBN treatment by that at 10 weeks' treatment. However, VEGF mRNA levels of rat bladders at 10 weeks' BBN treatment revealed a strong significant correlation with the incidence of bladder lesions at 26 weeks' treatment. Here, we suggest that quantitative VEGF mRNA levels are a good biomarker for a short‐term BBN‐induced bioassay for rat bladder carcinogenesis. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-28T09:25:42.146279-05:
      DOI: 10.1002/jat.3021
       
  • Developmental toxicity assay using high content screening of zebrafish
           embryos
    • Authors: Susan Lantz-McPeak; Xiaoqing Guo, Elvis Cuevas, Melanie Dumas, Glenn D. Newport, Syed F. Ali, Merle G. Paule, Jyotshna Kanungo
      Abstract: Typically, time‐consuming standard toxicological assays using the zebrafish (Danio rerio) embryo model evaluate mortality and teratogenicity after exposure during the first 2 days post‐fertilization. Here we describe an automated image‐based high content screening (HCS) assay to identify the teratogenic/embryotoxic potential of compounds in zebrafish embryos in vivo. Automated image acquisition was performed using a high content microscope system. Further automated analysis of embryo length, as a statistically quantifiable endpoint of toxicity, was performed on images post‐acquisition. The biological effects of ethanol, nicotine, ketamine, caffeine, dimethyl sulfoxide and temperature on zebrafish embryos were assessed. This automated developmental toxicity assay, based on a growth‐retardation endpoint should be suitable for evaluating the effects of potential teratogens and developmental toxicants in a high throughput manner. This approach can significantly expedite the screening of potential teratogens and developmental toxicants, thereby improving the current risk assessment process by decreasing analysis time and required resources. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2014-05-28T09:20:58.316539-05:
      DOI: 10.1002/jat.3029
       
  • Cardiotoxicity evaluation of anthracyclines in zebrafish (Danio rerio)
    • Authors: Ying Han; Jing-pu Zhang, Jian-qin Qian, Chang-qin Hu
      Abstract: Drug‐induced cardiotoxicity is a leading factor for drug withdrawals, and limits drug efficacy and clinical use. Therefore, new alternative animal models and methods for drug safety evaluation have been given great attention. Anthracyclines (ANTs) are widely prescribed anticancer agents that have a cumulative dose relationship with cardiotoxicity. We performed experiments to study the toxicity of ANTs in early developing zebrafish embryos, especially their effects on the heart. LC50 values for daunorubicin, pirarubicin, doxorubicin (DOX), epirubicin and DOX‐liposome at 72 h post‐fertilization were 122.7 μM, 111.9 μM, 31.2 μM, 108.3 μM and 55.8 μM, respectively. At the same time, zebrafish embryos were exposed to ANTs in three exposure stages and induced incomplete looping of the heart tube, pericardia edema and bradycardia in a dose‐dependent manner, eventually leading to death. DOX caused the greatest heart defects in the treatment stages and its liposome reduced the effects on the heart, while daunorubicin produced the least toxicity. Genes and proteins related to heart development were also identified to be sensitive to ANT exposure and downregulated by ANTs. It revealed ANTs could disturb the heart formation and development. ANTs induced cardiotoxicity in zebrafish has similar effects in mammalian models, indicating that zebrafish may have a potential value for assessment of drug‐induced developmental cardiotoxicity. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-22T16:22:52.444139-05:
      DOI: 10.1002/jat.3007
       
  • A trivalent approach for determining in vitro toxicology: Examination of
           oxime K027
    • Authors: Adriana Prado; Georg A. Petroianu, Dietrich E. Lorke, Jeremy W. Chambers
      Abstract: Unforeseen toxic effects contribute to compound attrition during preclinical evaluation and clinical trials. Consequently, there is a need to correlate in vitro toxicity to in vivo and clinical outcomes quickly and effectively. We propose an expedited evaluation of physiological parameters in vitro that will improve the ability to predict in vivo toxicity of potential therapeutics. By monitoring metabolism, mitochondrial physiology and cell viability, our approach provides insight to the extent of drug toxicity in vitro. To implement our approach, we used human hepatocellular carcinoma cells (HepG2) and neuroblastoma cells (SH‐SY5Y) to monitor hepato‐ and neurotoxicity of the experimental oxime K027. We utilized a trivalent approach to measure metabolism, mitochondrial stress and induction of apoptosis in 96‐well formats. Any change in these three areas may suggest drug‐induced toxicity in vivo. K027 and pralidoxime, an oxime currently in clinical use, had no effect on glycolysis or oxygen consumption in HepG2 and SH‐SY5Y cells. Similarly, these oximes did not induce oxidant generation nor alter mitochondrial membrane potential. Further, K027 and pralidoxime failed to activate effector caspases, and these oximes did not alter viability. The chemotherapeutic agent, docetaxel, negatively affected metabolism, mitochondrial physiology and viability. Our studies present a streamlined high‐throughput trivalent approach for predicting toxicity in vitro, and this approach reveals that K027 has no measurable hepatotoxicity or neurotoxicity in vitro, which correlates with their in vivo data. This approach could eliminate toxic drugs from consideration for in vivo preclinical evaluation faster than existing toxicity prediction panels and ultimately prevent unnecessary experimentation. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-22T16:22:49.472421-05:
      DOI: 10.1002/jat.3013
       
  • Synergistic cytotoxicity and DNA strand breaks in cells and plasmid DNA
           exposed to uranyl acetate and ultraviolet radiation
    • Authors: Janice Wilson; Mary C. Zuniga, Filbert Yazzie, Diane M. Stearns
      Abstract: Depleted uranium (DU) has a chemical toxicity that is independent of its radioactivity. The purpose of this study was to explore the photoactivation of uranyl ion by ultraviolet (UV) radiation as a chemical mechanism of uranium genotoxicity. The ability of UVB (302 nm) and UVA (368 nm) radiation to photoactivate uranyl ion to produce single strand breaks was measured in pBR322 plasmid DNA, and the presence of adducts and apurinic/apyrimidinic sites that could be converted to single strand breaks by heat and piperidine was analyzed. Results showed that DNA lesions in plasmid DNA exposed to UVB‐ or UVA‐activated DU were only slightly heat reactive, but were piperidine sensitive. The cytotoxicity of UVB‐activated uranyl ion was measured in repair‐proficient and repair‐deficient Chinese hamster ovary cells and human keratinocyte HaCaT cells. The cytotoxicity of co‐exposures of uranyl ion and UVB radiation was dependent on the order of exposure and was greater than co‐exposures of arsenite and UVB radiation. Uranyl ion and UVB radiation were synergistically cytotoxic in cells, and cells exposed to photoactivated DU required different DNA repair pathways than cells exposed to non‐photoactivated DU. This study contributes to our understanding of the DNA lesions formed by DU, as well as their repair. Results suggest that excitation of uranyl ion by UV radiation can provide a pathway for uranyl ion to be chemically genotoxic in populations with dermal exposures to uranium and UV radiation, which would make skin an overlooked target organ for uranium exposures. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-15T09:03:01.061665-05:
      DOI: 10.1002/jat.3015
       
  • Endocrine disruption effects of p,p′‐DDE on juvenile zebrafish
    • Authors: Marta Sofia Monteiro; Maria Pavlaki, Augusto Faustino, Alexandra Rêma, Mariana Franchi, Letícia Gediel, Susana Loureiro, Inês Domingues, Jaime Rendón von Osten, Amadeu Mortágua Velho Maia Soares
      Abstract: The persistent organic pollutant p,p′‐DDE, the major metabolite of the insecticide DDT, has displayed evidence of endocrine disruption through the inhibition of androgen binding to androgen receptors in different species. Although p,p′‐DDE was continuously detected in wild fish with abnormal gonad development such as intersex, little is known about its mode of action during gonad development in fish. To elucidate the potential endocrine effects of this pollutant in zebrafish (Danio rerio), juveniles (30 days post hatch) were exposed to p,p′‐DDE during the critical window of sexual differentiation. Fish were exposed to sublethal concentrations ranging from 0.01 to 20 µg l–1 over 14 days and were maintained in control water for an additional 4 months. As core endpoints, the vitellogenin (vtg) concentration was measured at the end of exposure, and sex ratio and the gonadosomatic index were assessed 4 months after the end of exposure. An increase in vtg production in whole body homogenate was observed in fish exposed to 0.2 and 2.0 µg l–1 p,p′‐DDE. No significant differences were displayed in morphological parameters such as the gonadosomatic index of males and females or sex ratio. However, exposed females presented histopathological changes that include the reduction of the number of mature oocytes, which might impair their successful reproduction. These results demonstrate the ability of p,p′‐DDE to cause endocrine disruption in zebrafish exposed during gonad differentiation of juvenile specimens. Furthermore, vtg induction by p,p′‐DDE in juvenile zebrafish arises as a predictive marker for adverse effects of this DDT metabolite on the ovarian function of female zebrafish. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-15T08:55:11.837345-05:
      DOI: 10.1002/jat.3014
       
  • Nitroaromatic compounds: Environmental toxicity, carcinogenicity,
           mutagenicity, therapy and mechanism
    • Authors: Peter Kovacic; Ratnasamy Somanathan
      Pages: 810 - 824
      Abstract: Vehicle pollution is an increasing problem in the industrial world. Aromatic nitro compounds comprise a significant portion of the threat. In this review, the class includes nitro derivatives of benzene, biphenyls, naphthalenes, benzanthrone and polycyclic aromatic hydrocarbons, plus nitroheteroaromatic compounds. The numerous toxic manifestations are discussed. An appreciable number of drugs incorporate the nitroaromatic structure. The mechanistic aspects of both toxicity and therapy are addressed in the context of a unifying mechanism involving electron transfer, reactive oxygen species, oxidative stress and antioxidants. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-02-16T22:23:29.607563-05:
      DOI: 10.1002/jat.2980
       
  • Toxicity of imine–iminium dyes and pigments: electron transfer,
           radicals, oxidative stress and other physiological effects
    • Authors: Peter Kovacic; Ratnasamy Somanathan
      First page: 825
      Abstract: Although conjugation is well known as an important contributor to color, there is scant recognition concerning involvement of imine and iminium functions in the physiological effects of this class of dyes and pigments. The group includes the dyes methylene blue, rhodamine, malachite green, fuchsin, crystal violet, auramine and cyanins, in addition to the pigments consisting of pyocyanine, phthalocyanine and pheophytin. The physiological effects consist of both toxicity and beneficial aspects. The unifying theme of electron transfer–reactive oxygen species–oxidative stress is used as the rationale in both cases. Toxicity is frequently prevented or alleviated by antioxidants. The apparent dichotomy of methylene blue action as both oxidant and antioxidant is rationalized based on similar previous cases. This mechanistic approach may have practical benefit. This review is important in conveying, for the first time, a unifying mechanism for toxicity based on electron transfer–reactive oxygen species–oxidative stress arising from imine–iminium. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-05-22T16:22:54.672557-05:
      DOI: 10.1002/jat.3005
       
  • Inhibition of cytochrome P450s enhances (+)-usnic acid cytotoxicity in
           primary cultured rat hepatocytes
    • Authors: Qiang Shi; James Greenhaw, William F. Salminen
      Pages: 835 - 840
      Abstract: (+)-Usnic acid (UA) is consumed as a dietary supplement to promote weight loss; however, dietary supplements containing UA have been associated with clinical cases of severe liver injury. UA has been shown to be hepatotoxic in rats and is extensively metabolized by hepatic cytochrome P450s (CYPs); therefore, we examined if UA metabolism results in the formation of cytotoxic metabolites or if metabolism is a detoxification process in primary rat hepatocytes. When CYP activity was suppressed by the non-isoenzyme-selective inhibitor SKF-525A (20 μM), or the CYP1A inhibitor alpha-naphthoflavone (10 μM), or the CYP3A inhibitor ketoconazole (25 μM), the cytotoxicity of UA at 3 ~ 6 μM after 3 ~ 20 h of exposure was significantly increased as measured by lactate dehydrogenase (LDH) leakage. At 2 h after UA exposure, an earlier time point prior to LDH release, these CYP inhibitors potentiated UA-induced inhibition of cellular respiration as determined by the Clark type oxygen electrode. Cellular adenosine triphosphate (ATP) depletion by UA was also exacerbated by these CYP inhibitors. The CYP2B/2C inhibitor, ticlopidine at 20 μM, showed no effects in parallel experiments. These data demonstrate that UA is bio-transformed to less toxic metabolites in rat primary hepatocytes, probably mainly by CYP1A and 3A, but not 2B/2C. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2013-05-20T05:34:49.380555-05:
      DOI: 10.1002/jat.2892
       
  • N-hexane inhalation during pregnancy alters DNA promoter methylation in
           the ovarian granulosa cells of rat offspring
    • Authors: Hong Li; Jin Liu, Yan Sun, Wenxiang Wang, Shaozheng Weng, Shihua Xiao, Huiling Huang, Wenchang Zhang
      Pages: 841 - 856
      Abstract: The N-hexane-induced impact on the reproductive system of the offspring of animals exposed to n-hexane has caused great concern. Pregnant Wistar rats inhaled 500, 2 500 or 12 500 ppm n-hexane during gestational days 1–20. Clinical characteristics and developmental indices were observed. Ovarian granulosa cells were extracted from F1 rats, the number of follicles was determined in ovarian slices and promoter methylation was assessed using MeDIP-Chip. Several methods were used to analyze the scanned genes, including the Gene Ontology Consortium tools, the DAVID Functional Annotation Clustering Tool, hierarchical clustering and KEGG pathway analysis. The results indicated that the live pups/litter ratio was significantly lowest in the 12 500 ppm group. A significant decrease in secondary follicles and an increase in atresic follicles were observed in the 12 500 ppm group. The number of shared demethylated genes was higher than that of the methylated genes, and the differentially methylated genes were enriched in cell death and apoptosis, cell growth and hormone regulation. The methylation profiles of the offspring from the 500 ppm and control groups were different from those of the 2500 and 12 500 ppm groups. Furthermore, the methylation status of genes in the PI3K-Akt and NF-kappa B signaling pathways was changed after n-hexane exposure. The Cyp11a1, Cyp17a1, Hsd3b1, Cyp1a1 and Srd5a1 promoters were hypermethylated in the n-hexane-exposed groups. These results indicate that the developmental toxicity of n-hexane in F1 ovaries is accompanied by the altered methylation of promoters of genes associated with apoptotic processes and steroid hormone biosynthesis. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-06-06T05:49:26.916836-05:
      DOI: 10.1002/jat.2893
       
  • Dermal irritation of petrolatum in rabbits but not in mice, rats or
           minipigs
    • Authors: S. A. Chandra; R. A. Peterson, D. Melich, C. M. Merrill, D. Bailey, K. Mellon-Kusibab, R. Adler
      Pages: 857 - 861
      Abstract: Petrolatum is widely used in cosmetics, topical pharmaceuticals and also as a vehicle in dermal toxicity studies. New Zealand white rabbits treated with white petrolatum (vehicle control) in a 2-week dermal irritation study exhibited moderate to severe erythema starting on Day 7 that subsided towards the end of the study. Histological examination of abraded and non-abraded petrolatum-treated skin obtained at termination (Day 15) revealed mild acanthosis, hyperkeratosis, dermal edema with mixed inflammatory cells in the dermis. Macroscopic and microscopic features noted in rabbits were consistent with dermal irritation to petrolatum. Wistar-Han rats, CD1 mice, C57/Bl/6J mice and Göttingen minipigs treated topically with white petrolatum did not exhibit clinical or histologic evidence of dermal irritation. Therapeutic agents developed for topical application are generally tested in rabbits during some point in development. Interpretation of skin irritation data from a single species can impact risk assessment for humans and on product labeling. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-05-30T07:16:54.557287-05:
      DOI: 10.1002/jat.2895
       
  • Role of methotrexate exposure in apoptosis and proliferation during early
           neurulation
    • Authors: Xiuwei Wang; Jianhua Wang, Tao Guan, Qian Xiang, Mingsheng Wang, Zhen Guan, Guannan Li, Zhiqiang Zhu, Qiu Xie, Ting Zhang, Bo Niu
      Pages: 862 - 869
      Abstract: Apoptosis and proliferation play important roles in embryonic development and are required for neural tube closure. The antifolate drug methotrexate (MTX) induces folate dysmetabolism by inhibition of dihydrofolate reductase and causes abnormal apoptosis and proliferation. In this study, we established an animal model of neural tube defects (NTDs) using MTX to investigate the role of apoptosis and proliferation in NTDs caused by folate deficiency. Differential gene expressions were studied by microarray and reverse transcription–polymerase chain reaction in the NTD animal model. Results showed that 30.8% of NTDs were caused by using MTX in treatment regimens. Microarray indicated that 166 genes were significantly different between the control and NTD mice, including four apoptosis-related genes (Endog, Trp53, Casp3, Bax) and three proliferation-related genes (Ptch1, Pla2g4a, Foxg1). Levels of Endog, Trp53, Casp3, Bax (fold change > 1.5) were upregulated but Ptch1, Pla2g4a, Foxg1 (fold change 
      PubDate: 2013-07-09T02:17:27.110799-05:
      DOI: 10.1002/jat.2901
       
  • Cytotoxic effects of the quinolone levofloxacin on rabbit meniscus cells
    • Authors: Linlong Wang; Yunpeng Wu, Yang Tan, Xi Fei, Yu Deng, Hong Cao, Biao Chen, Hui Wang, Jacques Magdalou, Liaobin Chen
      Pages: 870 - 877
      Abstract: Quinolones have been reported to induce adverse effects on articular cartilage, tendons and ligaments. However, the effects of quinolones on menisci have not been revealed. The present study was to test the effects of levofloxacin on meniscus cells in vitro. Rabbit meniscus cells were administrated with different concentrations of levofloxacin (0, 14, 28, 56, 112 and 224 µm) for 24 or 48 h, and cell viability and apoptosis were measured. The mRNA expression levels of matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, tissue inhibitors of metalloproteinase (TIMP)-1, TIMP-3, Col1a1, Bcl-2, caspase-3 and inducible nitric oxide were analyzed by real-time polymerase chain reaction. Active caspase-3 was detected by immunocytochemical assay, while protein expression levels of MMP-3 and MMP-13 were measured by Western blotting assay. After treatment with levofloxacin for 48 h, cell viability was decreased from dose of 28 to 224 µm in a concentration-dependent manner. An increase of apoptotic cells was observed by flow cytometry. Active caspase-3 protein expression level was also increased. The mRNA level of Bcl-2 was decreased and levels of MMP-1, MMP-3 and MMP-13 in experimental groups were higher than those of controls. The protein levels of MMP-3 and MMP-13 were increased. Moreover, the mRNA levels of TIMP-3 and col1a1 were decreased. A dose-dependent increase of inducible nitric oxide mRNA expression level was also observed. Our results suggested the cytotoxic effects of levofloxacin on meniscus cells through induction of apoptosis and unbalanced MMPs/TIMPs expression. These side effects might result in meniscus extracellular matrix degradation and meniscal lesion. Thus, quinolones should be used cautiously on patients who perform athletic activities or undergo surgical meniscus repair. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-07-01T04:23:22.929971-05:
      DOI: 10.1002/jat.2903
       
  • Metabolic pathways leading to detoxification of triptolide, a major active
           component of the herbal medicine Tripterygium wilfordii
    • Authors: Fuying Du; Zhaohua Liu, Xinxiu Li, Jie Xing
      Pages: 878 - 884
      Abstract: Triptolide (TP) shows promising anti-inflammatory and antitumor activity but with severe toxicity. TP is a natural reactive electrophile containing three epoxide groups, which are usually linked to hepatotoxicity via their ability to covalently bind to cellular macromolecules. In this study, metabolic pathways leading to detoxification of TP were evaluated in glutathione (GSH)-depleted (treated with L-buthionine-S,R-sulfoxinine, BSO) and aminobenzotriazole (ABT; a non-specific inhibitor for P450s)-treated mice. The toxicity of TP in mice was evaluated in terms of mortality and levels of serum alanine transaminase (ALT). In incubates with NADPH- and GSH-supplemented liver microsomes, seven GSH conjugates derived from TP were detected. In mice, these hydrolytically unstable GSH conjugates underwent γ-glutamyltranspeptidase/dipeptidases-mediated hydrolysis leading to two major cysteinylglycine conjugates, which underwent further hydrolysis by dipeptidases to form two cysteine conjugates of TP. In ABT-treated mice, the hydroxylated metabolites of TP were found at a lower level than normal mice, and their subsequent conjugated metabolites were not found. The level of cysteinylglycine and cysteine conjugates derived from NADPH-independent metabolism increased in mice treated with both TP and BSO (or ABT), which could be the stress response to toxicity of TP. Compared with normal mice, mortality and ALT levels were significantly higher in TP-treated mice, indicating the toxicity of TP. Pretreatment of ABT increased the toxicity caused by TP, whereas the mortality decreased in GSH-depleted mice. Metabolism by cytochrome P450 enzymes to less reactive metabolites implied a high potential for detoxification of TP. The GSH conjugation pathway also contributed to TP's detoxification in mice. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-07-09T01:59:47.600008-05:
      DOI: 10.1002/jat.2906
       
  • DNA fragmentation induced by all-trans retinoic acid and its steroidal
           analogue EA-4 in C2C12 mouse and HL-60 human leukemic cells in vitro
    • Authors: Raghda S. Alakhras; Georgia Stephanou, Nikos A. Demopoulos, Konstantinos Grintzalis, Christos D. Georgiou, Sotirios S. Nikolaropoulos
      Pages: 885 - 892
      Abstract: We have recently shown that retinoic acid induces micronucleation mainly via chromosome breakage (Alakhras et al. Cancer Lett 2011; 306: 15–26). To further study retinoic acid clastogenicity and evaluate DNA damaging potential we investigated the ability of (a) all-trans retinoic acid and its steroidal analogue EA-4 to induce DNA fragmentation by using Comet assay under alkaline unwinding and neutral condition electrophoresis, and (b) the retinoids under study to induce small (0–1 kb) DNA fragments. Two cell lines, C2C12 mouse cells and HL-60 human leukemic cells were used in this study. We found that all-trans retinoic acid and its steroidal analogue EA-4 (a) provoke DNA migration due to DNA fragmentation as it is shown by the increased values of Comet parameters, and (b) induce significantly small-size fragmented genomic DNA as indicated by the quantification of necrotic/apoptotic small DNA segments in both cell systems. A different response between the two cell lines was observed in relation to retinoid ability to increase the percentage of DNA in the tail as well as break DNA in to small fragments. Our findings confirm the ability of retinoic acid to provoke micronucleation by disrupting DNA into fragments, among which small pieces of double-stranded DNA up to 1 kb are identified. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-08-02T01:23:16.668915-05:
      DOI: 10.1002/jat.2908
       
  • The alkylphenols 4-nonylphenol, 4-tert-octylphenol and 4-tert-butylphenol
           aggravate atopic dermatitis-like skin lesions in NC/Nga mice
    • Authors: Kaori Sadakane; Takamichi Ichinose, Hirohisa Takano, Rie Yanagisawa, Eiko Koike, Ken-ichiro Inoue
      Pages: 893 - 902
      Abstract: Phthalate esters in plastics act as adjuvants for immunoglobulin production, which aggravates allergic disease. However, the effects of alkylphenols (used as plasticizers and surfactants) on atopic dermatitis have not been studied in detail. Therefore, the goal of the present study was to investigate the effects of the alkylphenols 4-nonylphenol (NP), 4-tert-octylphenol (OP) and 4-tert-butylphenol (BP) in a murine model of atopic dermatitis. NC/Nga mice were intraperitoneally administered NP, OP or BP and were subcutaneously injected with mite allergen in one ear to induce atopic dermatitis-like skin lesions (ADSLs). The condition of the skin was observed, and the levels of immunoglobulin in serum and inflammatory cytokines in lesions were determined. NP exacerbated mite allergen-induced ADSLs according to dose. OP and BP also significantly exacerbated skin lesions but not as a function of dose. Alkylphenols tended to increase the levels of IgE and antigen-specific IgG1 in serum. Further, the treatment of the alkylphenols increased the expression in lesions of inflammatory cytokines, interleukin-4 and monocyte chemotactic protein-3. Thymic stromal lymphopoietin levels increased according to ADSL severity. In contrast, the levels of the T-helper 1 cytokines (interleukin-18 and interferon-gamma) decreased. NP, OP or BP may enhance T-helper 2-type immune responses in NC/Nga mice, which aggravates mite allergen-induced ADSLs. Therefore, the uptake of very low levels of alkylphenols may contribute to the increase in the incidence of atopic dermatitis. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-08-23T22:56:22.034266-05:
      DOI: 10.1002/jat.2911
       
  • In vitro protection by pyruvate against cadmium-induced cytotoxicity in
           hippocampal HT-22 cells
    • Authors: Ethan Poteet; Ali Winters, Luokun Xie, Myoung-Gwi Ryou, Ran Liu, Shao-Hua Yang
      Pages: 903 - 913
      Abstract: Cadmium is a toxic metal with no biological function in higher-order mammals. Humans are exposed to cadmium environmental contamination and the mechanism underlying the cadmium's cytotoxicity is unclear. To better understand this mechanism, we employed murine hippocampal HT-22 cells to test the in vitro effects of cadmium toxicity. Our study indicated that cadmium inhibits both mitochondria oxidative phosphorylation and glycolysis. In turn, this causes depolarization of mitochondrial membrane potential, increase of superoxide production and decrease of ATP generation. Furthermore, we demonstrated that the detrimental action of cadmium in bioenergetics could be mitigated by pyruvate, an intermediate metabolic product. Pyruvate decreased superoxide production, maintained mitochondrial membrane potential, restored glycolysis, mitigated the decrease in cellular ATP and attenuated cadmium cytotoxicity. Our study provides the first evidence that pyruvate might offer promising therapy for cadmium poisoning. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-08-30T03:18:22.64168-05:0
      DOI: 10.1002/jat.2913
       
  • Increased methylmercury toxicity related to obesity in diabetic KK-Ay mice
    • Authors: Megumi Yamamoto; Rie Yanagisawa, Eriko Motomura, Masaaki Nakamura, Mineshi Sakamoto, Motohiro Takeya, Komyo Eto
      Pages: 914 - 923
      Abstract: We examined the toxic effects of methylmercury (MeHg) in KK-Ay type 2 diabetic mice to clarify how metabolic changes associated with type 2 diabetes mellitus affect MeHg toxicity. MeHg (5 mg Hg kg –1day–1 p.o.) was given to 4-week-old male KK-Ay and C57BL/6J (BL/6) mice three times per week for 6 weeks. Average body weights (BW) of vehicle-treated BL/6 and KK-Ay mice were 16.3 and 16.4 g respectively on the first day, and 24.8 and 42.3 g respectively on the last day of the experiment. MeHg-treated KK-Ay mice began to lose weight about 5 weeks after MeHg administration. Six of seven MeHg-treated KK-Ay mice showed hind-limb clasping in the final stage of the experiment. The mean blood mercury level of MeHg-treated KK-Ay mice reached a maximum of 9.8 µg ml–1, whereas that of the MeHg-treated BL/6 mice was 2.8 µg ml–1 after 10 days of treatment. The average total mercury concentrations in the cerebrum and epididymal fat pad were 7.4 and 0.57 µg g–1, respectively, for BL/6 mice and 27 and 1.6 µg g–1, respectively, for KK-Ay mice. In MeHg-treated KK-Ay mice with neurological symptoms, CD204-positive macrophages were observed in the brain, kidney and spleen, indicating CD204 could be a marker for injured tissues. BW loss and significant pathological changes were not observed in other groups of mice. These results indicate that body fat gain in type 2 diabetes mellitus and low mercury accumulation in adipose tissue increased MeHg concentrations in organs and enhanced toxicity in KK-Ay mice at the same dose of MeHg per BW. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-15T03:22:53.03781-05:0
      DOI: 10.1002/jat.2954
       
  • A proposal to improve clarity and communication in the EU Classification
           process for chemicals for carcinogenicity and reproductive and
           developmental toxicity
    • Abstract: There is an issue in the EU classification of substances for carcinogenicity and for reproductive or developmental toxicity which has brought difficulties to those involved in the process. The issue lies in the inability of the classification system to distinguish between carcinogens and reproductive toxicants with different levels of concern. This has its origins in the early years of toxicology when it was thought that a relatively small number of chemicals would be either carcinogens or reproductive toxicants, but this has turned out not to be the case. This can cause problems in communicating to the users of chemicals, including the public, the nature of the hazard presented by chemicals. Processes have been developed within the classification system for setting specific concentration limits which assess the degree of hazard for carcinogens and reproductive toxicants as high, medium or low. However these categories are not otherwise used in classification. It is proposed that their wider use would bring the advantages of transparency, clarity of communication, certainty of the process and would allow chemicals with a high degree of hazard to be identified and managed in an appropriate way. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Elevated levels of antibodies against xenobiotics in a subgroup of healthy
           subjects
    • Abstract: In spite of numerous research efforts, the exact etiology of autoimmune diseases remains largely unknown. Genetics and environmental factors, including xenobiotics, are believed to be involved in the induction of autoimmune disease. Some environmental chemicals, acting as haptens, can bind to a high‐molecular‐weight carrier protein such as human serum albumin (HSA), causing the immune system to misidentify self‐tissue as an invader and launch an immune response against it, leading to autoimmunity. This study aimed to examine the percentage of blood samples from healthy donors in which chemical agents mounted immune challenges and produced antibodies against HSA‐bound chemicals. The levels of specific antibodies against 12 different chemicals bound to HSA were measured by ELISA in serum from 400 blood donors. We found that 10% (IgG) and 17% (IgM) of tested individuals showed significant antibody elevation against aflatoxin‐HSA adduct. The percentage of elevation against the other 11 chemicals ranged from 8% to 22% (IgG) and 13% to 18% (IgM). Performance of serial dilution and inhibition of the chemical–antibody reaction by specific antigens but not by non‐specific antigens were indicative of the specificity of these antibodies. Although we lack information about chemical exposure in the tested individuals, detection of antibodies against various protein adducts may indicate chronic exposure to these chemical haptens in about 20% of the tested individuals. Currently the pathological significance of these antibodies in human blood is still unclear, and this protein adduct formation could be one of the mechanisms by which environmental chemicals induce autoimmune reactivity in a significant percentage of the population. Copyright © 2014. The
      Authors . Journal of Applied Toxicology Published by John Wiley & Sons Ltd.
       
  • Cytotoxic and apoptotic activities of the plancitoxin I from the venom of
           crown‐of‐thorns starfish (Acanthaster planci) on A375.S2 cells
           
    • Abstract: This study reports on a cytotoxic toxin derived from the venom of the crown‐of‐thorns starfish Acanthaster planci (CAV). The protein toxin was isolated through both ion‐exchange and gel‐filtration chromatography, and characterized by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and mass spectrum analyzes. The CAV was identified as plancitoxin I protein. The mechanistic role of the CAV toxin was explored in human malignant melanoma A375.S2 cell death. The results indicated that after incubation with CAV toxin, cells significantly decreased in A375.S2 cell viability and increased in the lactate dehydrogenase (LDH) level in a dose‐dependent manner. The assays indicated that CAV toxin promoted reactive oxygen species (ROS) production, induced nitric oxide (NO) formation, lost mitochondrial membrane potential (ΔΨm) and induced inter‐nucleosomal DNA fragmentation in A375.S2 cells. The molecular cytotoxicity of the CAV toxin was tested through evaluation of the apoptosis/necrosis ratio by double staining with annexin V‐FITC and a propidium iodide (PI) assay. The results suggested that CAV toxin induced a cytotoxic effect in A375.S2 cells via the apoptotic procedure, and may be associated with the regulation of the p38 pathways. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Parabens can enable hallmarks and characteristics of cancer in human
           breast epithelial cells: a review of the literature with reference to new
           exposure data and regulatory status
    • Abstract: A framework for understanding the complexity of cancer development was established by Hanahan and Weinberg in their definition of the hallmarks of cancer. In this review, we consider the evidence that parabens can enable development in human breast epithelial cells of four of six of the basic hallmarks, one of two of the emerging hallmarks and one of two of the enabling characteristics. In Hallmark 1, parabens have been measured as present in 99% of human breast tissue samples, possess oestrogenic activity and can stimulate sustained proliferation of human breast cancer cells at concentrations measurable in the breast. In Hallmark 2, parabens can inhibit the suppression of breast cancer cell growth by hydroxytamoxifen, and through binding to the oestrogen‐related receptor gamma may prevent its deactivation by growth inhibitors. In Hallmark 3, in the 10 nM–1 μM range, parabens give a dose‐dependent evasion of apoptosis in high‐risk donor breast epithelial cells. In Hallmark 4, long‐term exposure (>20 weeks) to parabens leads to increased migratory and invasive activity in human breast cancer cells, properties that are linked to the metastatic process. As an emerging hallmark methylparaben has been shown in human breast epithelial cells to increase mTOR, a key regulator of energy metabolism. As an enabling characteristic parabens can cause DNA damage at high concentrations in the short term but more work is needed to investigate long‐term, low‐dose mixtures. The ability of parabens to enable multiple cancer hallmarks in human breast epithelial cells provides grounds for regulatory review of the implications of the presence of parabens in human breast tissue. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Characterization of Oryzias latipes glucocorticoid receptors and their
           unique response to progestins
    • Abstract: Various receptor bioassays, including estrogens, androgens and thyroid hormones, have been developed and applied successfully for assessing hormone function in a wide range of animal species, including fish. In fish, corticosteroids play a pivotal role in physiology as they do in mammals, but far less is known about the corticosteroid receptor system in fish compared with in mammals. Here we established a transient transactivation assay using the Japanese medaka, Oryzias latipes, glucocorticoid receptors (olGRs) and mineralocorticoid receptor to analyse their functional properties in a fish. We found that olGR2 was highly responsive to glucocorticoids, similar to the human GR, whereas the olGR1 subtype was minimally responsive. Thus, olGR2 most likely mediates glucocorticoid signaling in medaka. We further tested crosstalk between GRs and other steroid hormones, and found that progestins could activate or inactivate olGR2‐mediating transcription, depending on the presence or absence of cortisol. The transactivation assays developed for medaka GRs provide tools to gain useful insights into corticosteroid signaling in fish and for in vitro screening of environmental substances activating GRs. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • In vitro evaluation of the effects of perfluorooctanesulfonic acid (PFOS)
           and perfluorooctanoic acid (PFOA) on IL‐2 production in human
           T‐cells
    • Abstract: Perfluorinated compounds, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been shown to alter various immune functions suggesting they are immunotoxic. This study assessed the effects of PFOS and PFOA on interleukin (IL)‐2 production in the human Jurkat T‐cell line and PFOS in healthy human primary T cells. Jurkat cells were stimulated with phytohemagglutinin (PHA)/phorbol myristate acetate (PMA), anti CD‐3/anti CD‐28, or anti CD‐3, and dosed with 0, 0.05, 0.1, 0.5, 1, 5, 10, 50, 75, or 100 µg ml−1 PFOS or 0, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, or 10 µg ml−1 PFOA. Jurkat cells stimulated with PHA/PMA or anti CD‐3 exhibited decreased IL‐2 production beginning at 50 µg PFOS ml−1 and 5 µg PFOS ml−1 respectively, but stimulation with anti‐CD3/anti‐CD28 resulted in no changes compared with the control. Addition of the PPAR‐alpha antagonist GW6471 to PFOS‐dosed cells stimulated with PHA/PMA resulted in decreases in IL‐2 production starting at 50 µg PFOS ml−1, which suggests PFOS affected T‐cell IL‐2 production via PPAR‐alpha‐independent mechanisms. Exposure to PFOA, PFOA + GW6471, or PFOS + PFOA in Jurkat cells resulted in no significant differences in IL‐2 production. In vitro dosing studies using healthy primary human CD4+ T cells were consistent with the Jurkat results. These data demonstrated that PFOA did not impact IL‐2 production, but PFOS suppressed IL‐2 production in both a human cell line and human primary cells at dose levels within the high end of the human exposure range. A decrease in IL‐2 production is characteristic of autoimmune diseases such as systemic lupus erythematosus and should be further investigated. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Diisocyanates, occupational asthma and IgE antibody: implications for
           hazard characterization
    • Abstract: Sensitization of the respiratory tract by chemicals resulting in rhinitis and asthma is an important occupational health issue. Occupational asthma is associated with significant morbidity and can be fatal. Tests for the identification and characterization of chemicals with the potential to cause sensitization of the respiratory tract are lacking. In spite of sustained interest there are no validated or widely accepted methods available, and this presents toxicologists with a considerable challenge. One important constraint on the development of appropriate testing strategies has been uncertainty and controversy about the immunological mechanisms through which chemicals may induce sensitization of the respiratory tract. By analogy with protein respiratory allergy it is legitimate to consider that IgE antibody‐dependent mechanisms may play a pivotal role. However, although many aspects of chemical respiratory allergy are consistent with reactions caused by IgE antibody, uncertainty remains because among patients with occupational asthma caused by chemical respiratory allergens there are commonly a proportion, and sometimes a significant proportion, of subjects that lack detectable IgE antibody. Here we consider the relevance of IgE antibody responses for the development of a chemical respiratory allergy to diisocyanates. A case is made that IgE antibody responses are, either directly or indirectly, closely associated with occupational asthma to the diisocyanates (and to other chemical respiratory allergens). As such the argument is advanced here that IgE antibody represents an appropriate readout for the characterization of chemical respiratory allergens, and that uncertainty about mode of action should no longer represent a hurdle in the development of suitable test methods. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Toxicity profiles and solvent–toxicant interference in the planarian
           Schmidtea mediterranea after dimethylsulfoxide (DMSO) exposure
    • Abstract: To investigate hydrophobic test compounds in toxicological studies, solvents like dimethylsulfoxide (DMSO) are inevitable. However, using these solvents, the interpretation of test compound‐induced responses can be biased. DMSO concentration guidelines are available, but are mostly based on acute exposures involving one specific toxicity endpoint. Hence, to avoid solvent–toxicant interference, we use multiple chronic test endpoints for additional interpretation of DMSO concentrations and propose a statistical model to assess possible synergistic, antagonistic or additive effects of test compounds and their solvents. In this study, the effects of both short‐ (1 day) and long‐term (2 weeks) exposures to low DMSO concentrations (up to 1000 µl l−1) were studied in the planarian Schmidtea mediterranea. We measured different biological levels in both fully developed and developing animals. In a long‐term exposure set‐up, a concentration of 500 µl l−1 DMSO interfered with processes on different biological levels, e.g. behaviour, stem cell proliferation and gene expression profiles. After short exposure times, 500 µl l−1 DMSO only affected motility, whereas the most significant changes on different parameters were observed at a concentration of 1000 µl l−1 DMSO. As small sensitivity differences exist between biological levels and developmental stages, we advise the use of this solvent in concentrations below 500 µl l−1 in this organism. In the second part of our study, we propose a statistical approach to account for solvent–toxicant interactions and discuss full‐scale solvent toxicity studies. In conclusion, we reassessed DMSO concentration limits for different experimental endpoints in the planarian S. mediterranea. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Toxicity of new emerging pollutant tris‐(2,3‐dibromopropyl)
           isocyanurate on BALB/c mice
    • Abstract: The emerging heterocyclic brominated flame retardant tris‐(2,3‐dibromopropyl) isocyanurate (TBC), widely used in reinforced plastics, has demonstrated toxicity to fish. However, little is known about its toxicity in rodents. This study aims to determine the effect of TBC on growth, biochemical parameters in serum, organs and related gene expression of both male and female BALB/c mice after gastro‐gavage administration of 0, 2, 10 and 50 mg kg−1 TBC for 28 days. Results indicated that exposure to TBC had no effects on basic growth and food intake of mice, but significantly increased serum alanine aminotransferase levels in male mice. Histopathological analyses showed that focal necrosis (2, 10 and 50 mg kg−1 TBC‐exposed groups) and ballooning degeneration (10 and 50 mg kg−1 TBC‐exposed groups) were found in mouse liver, whereas transmission electron microscopy revealed dose‐dependent hepatocyte apoptosis, mitochondrial degeneration and endoplasmic reticulum dilation. Histopathological and ultrastructural assessments in the lung showed dose‐dependent hyperplasia of pulmonary alveolar epithelium, bronchial congestion, infiltration of inflammatory cells and mitochondrial swelling following TBC exposure. Our results also indicated that mitochondria are one of the major target cytoplasmic organelles for TBC, suggesting that damage in mitochondria is one of the pathways that led to toxic effects in the liver and lung of TBC‐treated groups. Moreover, TBC effectively activated the gene expression of p53 in mice liver. Our findings provide strong evidence that TBC induces significant toxicity in mice organs, especially in liver and lung, which play vital roles in detoxification and gas exchange, respectively. This research will contribute to characterize the toxic effects of TBC, which was introduced as one of the candidates for brominated flame retardant replacement. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Renal cells exposed to cadmium in vitro and in vivo: normalizing gene
           expression data
    • Abstract: Cadmium (Cd) is a toxic metal with a long half‐life in biological systems. This half‐life is partly as a result of metallothioneins (MTs), metal‐binding proteins with a high affinity for Cd. The high retention properties of the kidneys reside in proximal tubular cells that possess transport mechanisms for Cd‐MT uptake, ultimately leading to more Cd accumulation. Researchers have studied MT–metal interactions using various techniques including quantitative real‐time PCR (qPCR), an efficient tool for quantifying gene expression. Often a poor choice of reference genes, which is represented by their instability and condition dependency, leads to inefficient normalization of gene expression data and misinterpretations. This study demonstrates the importance of an efficient normalization strategy in toxicological research. A selection of stable reference genes was proposed in order to acquire reliable and reproducible gene quantification under metal stress using MT expression as an example. Moreover, in vitro and in vivo setups were compared to identify the influence of toxicological compounds in function of the experimental design. This study shows that glyceraldehyde‐3‐phosphate dehydrogenase (Gapdh), tyrosine monooxygenase/tryptophan5‐monooxygenase activation‐protein, zeta polypeptide (Ywhaz) and beta‐actin (Actb) are the most stable reference genes in a kidney proximal tubular cell line exposed to moderate and high Cd concentrations, applied as CdCl2. A slightly different sequence in reference gene stability was found in renal cells isolated from rats in vivo exposed to Cd. It was further shown that three reference genes are required for efficient normalization in this experimental setup. This study demonstrates the importance of an efficient normalization strategy in toxicological research. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Inhibitory effect of apocynin on methylglyoxal‐mediated glycation in
           osteoblastic MC3T3‐E1 cells
    • Abstract: Methylglyoxal (MG), a highly reactive metabolite of hyperglycemia, can enhance protein glycation, oxidative stress or inflammation. The present study investigated the effects of apocynin on the mechanisms associated with MG toxicity in osteoblastic MC3T3‐E1 cells. Pretreatment of MC3T3‐E1 cells with apocynin prevented the MG‐induced protein glycation and formation of intracellular reactive oxygen species and mitochondrial superoxide in MC3T3‐E1 cells. In addition, apocynin increased glutathione levels and restored the activity of glyoxalase I inhibited by MG. These findings suggest that apocynin provide a protective action against MG‐induced cell damage by reducing oxidative stress and by increasing the MG detoxification system. Apocynin treatment decreased the levels of proinflammatory cytokines such as tumor necrosis factor‐α and interleukin‐6 induced by MG. Additionally, the nitric oxide level reduced by MG was significantly increased by apocynin. These findings indicate that apocynin might exert its therapeutic effects via upregulation of glyoxalase system and antioxidant activity. Taken together, apocynin may prove to be an effective treatment for diabetic osteopathy. Copyright © 2014 John Wiley & Sons, Ltd.
       
  • Reactive oxygen species‐dependent JNK downregulated
           olaquindox‐induced autophagy in HepG2 cells
    • Abstract: Autophagy plays an important role in response to intracellular and extracellular stress to sustain cell survival. However, dysregulated or excessive autophagy may lead to cell death, known as “type II programmed cell death,” and it is closely associated with apoptosis. In our previous study, we proposed that olaquindox induced apoptosis of HepG2 cells through a caspase‐9 dependent mitochondrial pathway. In this study, we investigated autophagy induced by olaquindox and explored the crosstalk between apoptosis and autophagy in olaquindox‐treated HepG2 cells. Olaquindox‐induced autophagy was demonstrated by the accumulation of monodansylcadervarine, as well as elevated expression of autophagy‐related MAP‐LC3 and Beclin 1 proteins. The autophagy inhibitor 3‐methyladenine significantly increased the apoptotic rate induced by olaquindox, which was correlated with increased ratio of Bax/Bcl‐2. The further studies showed that olaquindox increased the levels of reactive oxygen species (ROS), and antioxidant N‐acetyl‐L‐cysteine (NAC) effectively blocked the accumulation of ROS but failed to block autophagy. Moreover, olaquindox induced the activation of c‐Jun N‐terminal protein kinase (JNK), and JNK inhibitor SP600125 failed to block autophagy. Instead, olaquindox‐induced autophagy was enhanced by NAC or SP600125. Meanwhile, JNK activation was remarkably blocked by NAC, indicating that ROS may be the upstream signaling molecules of JNK activation and involved in the negative regulation of olaquindox‐induced autophagy. These results suggest that olaquindox induces autophagy in HepG2 cells and that olaquindox‐induced apoptosis can be enhanced by 3‐methyladenine. Olaquindox‐induced autophagy in HepG2 cells is upregulated by Beclin 1 but downregulated by ROS‐dependent JNK. Copyright © 2014 John Wiley & Sons, Ltd.
       
 
 
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