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  Subjects -> ENVIRONMENTAL STUDIES (Total: 825 journals)
    - ENVIRONMENTAL STUDIES (754 journals)
    - POLLUTION (23 journals)
    - TOXICOLOGY AND ENVIRONMENTAL SAFETY (39 journals)
    - WASTE MANAGEMENT (9 journals)

ENVIRONMENTAL STUDIES (754 journals)            First | 1 2 3 4     

Showing 601 - 378 of 378 Journals sorted alphabetically
Political Studies Review     Hybrid Journal   (Followers: 15)
Population and Environment     Hybrid Journal   (Followers: 5)
Population Ecology     Hybrid Journal   (Followers: 10)
Population Studies: A Journal of Demography     Hybrid Journal   (Followers: 9)
Postcolonial Studies     Hybrid Journal   (Followers: 10)
Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management     Full-text available via subscription   (Followers: 2)
Presence Teleoperators & Virtual Environments     Hybrid Journal   (Followers: 1)
Present Environment and Sustainable Development     Open Access  
Presidential Studies Quarterly     Hybrid Journal   (Followers: 3)
Procedia Environmental Sciences     Open Access  
Proceedings of the Institution of Civil Engineers - Waste and Resource Management     Hybrid Journal   (Followers: 2)
Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment     Hybrid Journal   (Followers: 2)
Proceedings of the International Academy of Ecology and Environmental Sciences     Open Access   (Followers: 3)
Process Safety and Environmental Protection     Hybrid Journal   (Followers: 5)
Progress in Industrial Ecology, An International Journal     Hybrid Journal   (Followers: 4)
Przegląd Prawa Ochrony Środowiska     Open Access  
Psychological Assessment     Full-text available via subscription   (Followers: 7)
Public Money & Management     Hybrid Journal   (Followers: 9)
Public Works Management & Policy     Hybrid Journal   (Followers: 7)
Qatar Foundation Annual Research Forum Proceedings     Open Access   (Followers: 3)
Radioactivity in the Environment     Full-text available via subscription   (Followers: 4)
Regional Environmental Change     Hybrid Journal   (Followers: 3)
Regional Studies     Hybrid Journal   (Followers: 8)
Religious Studies     Hybrid Journal   (Followers: 11)
Remediation Journal     Hybrid Journal   (Followers: 5)
Remote Sensing Letters     Hybrid Journal   (Followers: 14)
Renaissance Studies     Hybrid Journal   (Followers: 15)
Rendiconti Lincei     Hybrid Journal  
Renewable Energy Focus     Full-text available via subscription   (Followers: 8)
Research & Reviews : Journal of Ecology     Full-text available via subscription   (Followers: 1)
Research and Practice for Persons with Severe Disabilities     Full-text available via subscription   (Followers: 4)
Research Journal of Environmental Sciences     Open Access   (Followers: 2)
Research Journal of Environmental Toxicology     Open Access   (Followers: 2)
ReSource     Full-text available via subscription  
Resources     Open Access  
Resources and Environment     Open Access   (Followers: 1)
Resources, Conservation and Recycling     Hybrid Journal   (Followers: 25)
Reuse/Recycle Newsletter     Hybrid Journal   (Followers: 1)
Review of English Studies     Hybrid Journal   (Followers: 6)
Review of Environmental Economics and Policy     Hybrid Journal   (Followers: 7)
Revista AIDIS de Ingeniería y Ciencias Ambientales. Investigación, desarrollo y práctica     Open Access  
Revista Ambivalências     Open Access  
Revista Brasileira de Engenharia Agrícola e Ambiental     Open Access   (Followers: 1)
Revista Capital Científico     Open Access  
Revista Chapingo. Serie Ciencias Forestales y del Ambiente     Open Access  
Revista de Ciências Ambientais     Open Access  
Revista de Ciencias Ambientales     Open Access  
Revista de Gestão Ambiental e Sustentabilidade - GeAS     Open Access  
Revista de Salud Ambiental     Open Access  
Revista Eletrônica de Gestão e Tecnologias Ambientais     Open Access  
Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental     Open Access  
Revista Eletrônica TECCEN     Open Access  
Revista Hábitat Sustenable     Open Access   (Followers: 1)
Revista Internacional de Ciências     Open Access  
Revista Meio Ambiente e Sustentabilidade     Open Access  
Revista Monografias Ambientais     Open Access  
Revista Verde de Agroecologia e Desenvolvimento Sustentável     Open Access   (Followers: 2)
Ring     Open Access   (Followers: 1)
Riparian Ecology and Conservation     Open Access   (Followers: 5)
Rivista di Studi sulla Sostenibilità     Full-text available via subscription  
Russian Journal of Ecology     Hybrid Journal   (Followers: 1)
S.A.P.I.EN.S     Open Access   (Followers: 2)
Safety Science     Hybrid Journal   (Followers: 16)
San Francisco Estuary and Watershed Science     Open Access   (Followers: 1)
SAR and QSAR in Environmental Research     Hybrid Journal  
Scandinavian Journal of Work, Environment & Health     Partially Free   (Followers: 12)
Scandinavian Political Studies     Hybrid Journal   (Followers: 6)
Science of The Total Environment     Hybrid Journal   (Followers: 16)
Sciences Eaux & Territoires : la Revue du Cemagref     Open Access  
Scientific Journal of Environmental Sciences     Open Access   (Followers: 1)
Scientific Studies of Reading     Hybrid Journal   (Followers: 3)
Sepsis     Hybrid Journal  
Slavery & Abolition: A Journal of Slave and Post-Slave Studies     Hybrid Journal   (Followers: 7)
Smart Grid and Renewable Energy     Open Access   (Followers: 8)
Social & Legal Studies     Hybrid Journal   (Followers: 11)
Social and Environmental Accountability Journal     Hybrid Journal   (Followers: 2)
Social Studies of Science     Hybrid Journal   (Followers: 21)
Soil and Sediment Contamination: An International Journal     Hybrid Journal   (Followers: 3)
Soil and Tillage Research     Hybrid Journal   (Followers: 6)
SourceOCDE Environnement et developpement durable     Full-text available via subscription   (Followers: 1)
SourceOECD Environment & Sustainable Development     Full-text available via subscription  
South Pacific Journal of Natural and Applied Sciences     Hybrid Journal  
Southern Forests : a Journal of Forest Science     Hybrid Journal   (Followers: 5)
Stochastic Environmental Research and Risk Assessment     Hybrid Journal   (Followers: 2)
Strategic Planning for Energy and the Environment     Hybrid Journal   (Followers: 4)
Studies in Christian Ethics     Hybrid Journal   (Followers: 7)
Studies in Conservation     Hybrid Journal   (Followers: 9)
Studies in Environmental Science     Full-text available via subscription   (Followers: 6)
Studies in Interreligious Dialogue     Full-text available via subscription   (Followers: 2)
Studies in Spirituality     Full-text available via subscription   (Followers: 7)
Sustainability     Open Access   (Followers: 17)
Sustainability of Water Quality and Ecology     Hybrid Journal   (Followers: 2)
Sustainable Cities and Society     Hybrid Journal   (Followers: 25)
Sustainable Development     Hybrid Journal   (Followers: 16)
Sustainable Development Law & Policy     Open Access   (Followers: 6)
Sustainable Environment Research     Open Access  
Sustainable Technologies, Systems & Policies     Open Access   (Followers: 9)
Sustentabilidade em Debate     Open Access  
TECHNE - Journal of Technology for Architecture and Environment     Open Access   (Followers: 5)
Tecnogestión     Open Access  
Territorio della Ricerca su Insediamenti e Ambiente. Rivista internazionale di cultura urbanistica     Open Access  
Tertiary Education and Management     Hybrid Journal   (Followers: 7)
The Historic Environment : Policy & Practice     Hybrid Journal   (Followers: 4)
The International Journal on Media Management     Hybrid Journal   (Followers: 4)
Theoretical Ecology     Hybrid Journal   (Followers: 9)
Theoretical Ecology Series     Full-text available via subscription   (Followers: 1)
Toxicologic Pathology     Hybrid Journal   (Followers: 15)
Toxicological & Environmental Chemistry     Hybrid Journal   (Followers: 4)
Toxicological Sciences     Hybrid Journal   (Followers: 9)
Toxicology     Hybrid Journal   (Followers: 17)
Toxicology and Applied Pharmacology     Hybrid Journal   (Followers: 16)
Toxicology and Industrial Health     Hybrid Journal   (Followers: 7)
Toxicology in Vitro     Hybrid Journal   (Followers: 11)
Toxicology Letters     Hybrid Journal   (Followers: 12)
Toxicology Mechanisms and Methods     Hybrid Journal   (Followers: 9)
Toxicon     Hybrid Journal   (Followers: 2)
Toxin Reviews     Hybrid Journal   (Followers: 1)
Trace Metals and other Contaminants in the Environment     Full-text available via subscription   (Followers: 2)
Trace Metals in the Environment     Full-text available via subscription   (Followers: 2)
Transition Studies Review     Hybrid Journal  
Transportation Research Part D: Transport and Environment     Hybrid Journal   (Followers: 27)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Trends in Ecology & Evolution     Full-text available via subscription   (Followers: 153)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 2)
Trends in Pharmacological Sciences     Full-text available via subscription   (Followers: 26)
Turkish Journal of Engineering and Environmental Sciences     Open Access   (Followers: 1)
UCLA Journal of Environmental Law and Policy     Open Access   (Followers: 4)
UD y la Geomática     Open Access  
Universidad y Ciencia     Open Access   (Followers: 1)
Urban Studies     Hybrid Journal   (Followers: 47)
Veredas do Direito : Direito Ambiental e Desenvolvimento Sustentável     Open Access  
VertigO - la revue électronique en sciences de l’environnement     Open Access   (Followers: 2)
Villanova Environmental Law Journal     Open Access  
Visitor Studies     Hybrid Journal   (Followers: 6)
Waste Management & Research     Hybrid Journal   (Followers: 10)
Water Environment Research     Full-text available via subscription   (Followers: 35)
Water International     Hybrid Journal   (Followers: 10)
Water, Air, & Soil Pollution     Hybrid Journal   (Followers: 22)
Water, Air, & Soil Pollution : Focus     Hybrid Journal   (Followers: 9)
Waterlines     Full-text available via subscription   (Followers: 2)
Weather and Forecasting     Full-text available via subscription   (Followers: 8)
Weather, Climate, and Society     Full-text available via subscription   (Followers: 8)
Web Ecology     Open Access   (Followers: 6)
Wetlands     Hybrid Journal   (Followers: 24)
Wilderness & Environmental Medicine     Hybrid Journal   (Followers: 2)
Wildlife Australia     Full-text available via subscription   (Followers: 2)
Wiley Interdisciplinary Reviews - Climate Change     Hybrid Journal   (Followers: 17)
Wiley Interdisciplinary Reviews : Energy and Environment     Hybrid Journal   (Followers: 4)
William & Mary Environmental Law and Policy Review     Open Access   (Followers: 2)
World Environment     Open Access   (Followers: 1)
World Journal of Entrepreneurship, Management and Sustainable Development     Hybrid Journal   (Followers: 4)
World Journal of Environmental Engineering     Open Access   (Followers: 2)
Worldviews: Global Religions, Culture, and Ecology     Hybrid Journal   (Followers: 8)
Zoology and Ecology     Hybrid Journal   (Followers: 3)
气候与环境研究     Full-text available via subscription   (Followers: 1)

  First | 1 2 3 4     

Journal Cover Journal of Applied Toxicology
  [SJR: 0.799]   [H-I: 53]   [13 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  [1597 journals]
  • Regucalcin counteracts tert‐butyl hydroperoxide and
           cadmium‐induced oxidative stress in rat testis
    • Abstract: Regucalcin (RGN) is a calcium (Ca2+)‐binding protein with multiple physiological roles and has also been linked to the suppression of oxidative stress. It is widely known that oxidative stress adversely affects spermatogenesis, disrupting the development of germ cells, and interfering with sperm function. The present study aims to analyze the role of RGN modulating testicular oxidative stress. To address this issue, seminiferous tubules (SeT) from transgenic rats overexpressing RGN (Tg‐RGN) and wild‐type (WT) were cultured ex vivo for 24 h in the presence/absence of pro‐oxidant stimuli, tert‐butyl hydroperoxide (TBHP, 250 and 500 μM) and cadmium chloride (Cd, 10 and 20 μM). Noteworthy, SeT from Tg‐RGN animals displayed a significantly higher antioxidant capacity and diminished levels of thiobarbituric acid reactive substances relatively to their WT counterparts, both in control and experimental conditions. Regarding the antioxidant defense systems, a significant increase in the activity of glutathione‐S‐transferase was found in the SeT of Tg‐RGN whereas no differences were observed in superoxide dismutase activity throughout experimental conditions. The activity of apoptosis executioner caspase‐3 was significantly increased in the SeT of WT rats treated with 250 μM of TBHP or 10 μM of Cd, an effect not seen in Tg‐RGN animals. These results showed that the SeT of Tg‐RGN animals displayed lower levels of oxidative stress and increased antioxidant defenses, exhibiting protection against oxidative damage and apoptosis. Moreover, the present findings support the antioxidant role of RGN in spermatogenesis, which may be an important issue of further research in the context of male infertility. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-25T02:46:48.66054-05:0
      DOI: 10.1002/jat.3333
       
  • Biodistribution of polyacrylic acid‐coated iron oxide nanoparticles
           is associated with proinflammatory activation and liver toxicity
    • Abstract: Iron oxide nanoparticles (IONs) have physical and chemical properties that render them useful for several new biomedical applications. Still, so far, in vivo safety studies of IONs with coatings of biomedical interest are still scarce. The aim of this study, therefore, was to clarify the acute biological effects of polyacrylic acid (PAA)‐coated IONs, by determining their biodistribution and their potential proinflammatory and toxic effects in CD‐1 mice. The biodistribution of PAA‐coated IONs in several organs (liver, spleen, kidneys, brain, heart, testes and lungs), the plasma cytokines, chemokine and aminotransferases levels, white blood cell count, oxidative stress parameters, adenosine triphosphate and histologic features of liver, spleen and kidneys were evaluated 24 h after a single acute (8, 20 or 50 mg kg−1) intravenous administration of PAA‐coated IONs in magnetite form. The obtained results showed that these IONs accumulate mainly in the liver and spleen and, to a lesser extent, in the lungs. Although our data showed that PAA‐coated IONs do not cause severe organ damage, an inflammatory process was triggered in vivo, as evidenced by as evidenced by increased neutrophils and large lymphocytes in the differential blood count. Moreover, an accumulation of iron in macrophages of the liver and spleen was observed and hepatic lipid peroxidation was elicited, showing that the IONs are able to induce oxidative stress. The effects of these nanoparticles need to be further investigated regarding the mechanisms involved and the long‐term consequences of intravenous administration of PAA‐coated IONs. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-22T04:16:14.285691-05:
      DOI: 10.1002/jat.3323
       
  • Neuroglial alterations in the zebrafish brain exposed to cadmium chloride
    • Authors: Antonio Monaco; Maria C. Grimaldi, Ida Ferrandino
      Abstract: Cadmium is an extremely toxic heavy metal that widely occurs in industrial workplaces with various hazardous effects on brain functions. The cytotoxic effects of cadmium chloride (CdCl2) on the neuroglial components of the zebrafish brain were analysed by detecting the glial fibrillary acidic protein (GFAP) expression and the mRNA levels of myelin genes mbp, mpz and plp1 in adult specimens exposed to cadmium for 2, 7 and 16 days. A significant decrease in the GFAP protein by Western blotting experiments was observed after 2 days of treatment, reaching 55% after 16 days. No change was observed in the mRNA levels. Using immunohistochemistry, a reduction in GFAP‐positive structures was revealed with a progressive trend in all the brains at 2, 7 and 16 days of treatment. In particular, a considerable reduction in GFAP‐positive fibres, with a different course, was observed in the ventricle areas and at the pial surface and in blood vessels after 16 days. Our experiments also showed a structural and chemical alteration of myelin and upregulation of mpz mRNA levels, the oligodendrocyte gene that is upregulated in experiments of neuronal injury, but not of plp1 and mbp mRNA levels, other myelin structural genes. These data confirm the toxic action of cadmium on the zebrafish brain. This action is time‐dependent and involves the glial cells, key components of the protection and function of nerve cells, hence the basis for many neurological diseases. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-15T04:01:49.760995-05:
      DOI: 10.1002/jat.3328
       
  • Impact of silver nanoparticles on marine diatom Skeletonema costatum
    • Authors: Jun Huang; Jinping Cheng, Jun Yi
      Abstract: When silver nanoparticles (AgNPs) are used commercially at a large scale, they infiltrate the environment at a rapid pace. However, the impact of large quantities of AgNPs on aquatic ecosystems is still largely unknown. In aquatic ecosystems, the phytoplanktons have a vital ecological function and, therefore, the potential impact of AgNPs on the microalgae community has elicited substantial concern. Therefore, in this study, the impacts of AgNPs on a marine diatom, the Skeletonema costatum, are investigated, with a focus on their photosynthesis and associated mechanisms. Exposure to AgNPs at a concentration of 0.5 mg l−1 significantly induces excess intracellular reactive oxygen species (ROS, 122%) and reduces 28% of their cell viability. More importantly, exposure to AgNPs reduces the algal chlorophyll‐a content. Scanning electron microscopy (SEM) was conducted, which revealed that AgNPs obstruct the light absorption of algae because they adhere to their surface. The maximum photochemical efficiency of photosystem II (Fv/Fm) demonstrates that exposure to AgNPs significantly inhibits the conversion of light energy into photosynthetic electron transport. Moreover, the genes of the photosystem II reaction center protein (D1) are significantly down‐regulated (P 
      PubDate: 2016-04-15T03:56:09.579116-05:
      DOI: 10.1002/jat.3325
       
  • Accounting for data variability, a key factor in in vivo/in vitro
           relationships: application to the skin sensitization potency (in vivo LLNA
           versus in vitro DPRA) example
    • Authors: S. Dimitrov; A. Detroyer, C. Piroird, C. Gomes, J. Eilstein, T. Pauloin, C. Kuseva, H. Ivanova, I. Popova, Y. Karakolev, S. Ringeissen, O. Mekenyan
      Abstract: When searching for alternative methods to animal testing, confidently rescaling an in vitro result to the corresponding in vivo classification is still a challenging problem. Although one of the most important factors affecting good correlation is sample characteristics, they are very rarely integrated into correlation studies. Usually, in these studies, it is implicitly assumed that both compared values are error‐free numbers, which they are not. In this work, we propose a general methodology to analyze and integrate data variability and thus confidence estimation when rescaling from one test to another. The methodology is demonstrated through the case study of rescaling the in vitro Direct Peptide Reactivity Assay (DPRA) reactivity to the in vivo Local Lymph Node Assay (LLNA) skin sensitization potency classifications. In a first step, a comprehensive statistical analysis evaluating the reliability and variability of LLNA and DPRA as such was done. These results allowed us to link the concept of gray zones and confidence probability, which in turn represents a new perspective for a more precise knowledge of the classification of chemicals within their in vivo OR in vitro test. Next, the novelty and practical value of our methodology introducing variability into the threshold optimization between the in vitro AND in vivo test resides in the fact that it attributes a confidence probability to the predicted classification. The methodology, classification and screening approach presented in this study are not restricted to skin sensitization only. They could be helpful also for fate, toxicity and health hazard assessment where plenty of in vitro and in chemico assays and/or QSARs models are available. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-15T03:45:36.191466-05:
      DOI: 10.1002/jat.3318
       
  • A 28‐year observational study of urinary cadmium and
           β2‐microglobulin concentrations in inhabitants in
           cadmium‐polluted areas in Japan
    • Authors: Hoang Duc Phuc; Teruhiko Kido, Ho Dung Manh, Le Thai Anh, Nguyen Thi Phuong Oanh, Rie Okamoto, Akie Ichimori, Kazuhiro Nogawa, Yasushi Suwazono, Hideaki Nakagawa
      Abstract: The biological half‐life of cadmium (Cd) is as long as 10–30 years. Exposure to this element induces renal tubular dysfunction, which is considered irreversible. β2‐microglobulin (β2‐MG) is a low‐molecular‐weight protein, and urinary β2‐MG is one of the most useful and critical indicators for the early detection of renal tubular dysfunction. However, very little research has been published concerning the long‐term observation of Cd‐induced adverse health effects. As such, this follow‐up study was conducted for 28 years to clarify the relationship between the concentration of Cd and β2‐MG in the urine of 28 inhabitants (14 male and 14 female) living in the Kakehashi River basin, Ishikawa prefecture (Japan), previously one of the most highly Cd‐polluted regions in this country. All subjects were over 60 years old in 2014 and participated in all six health examinations conducted over 28 years (1986–2014). Urine was collected at the appropriate time and kept frozen to analyze urinary Cd and β2‐MG concentrations. The urinary Cd concentration was found to decrease by nearly half between 1986 and 2008 in both male and female subjects, whereas it increased significantly from 2008 to 2014 in males. In contrast, urinary β2‐MG concentrations tended to increase over the 28‐year study period in both sexes. Urinary Cd and β2‐MG concentrations in females were significantly higher than those in males in this Cd‐polluted region. Age is more strongly associated with urinary β2‐MG concentration than recent Cd body burden. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-15T02:36:12.90087-05:0
      DOI: 10.1002/jat.3327
       
  • Airborne nanoparticles (PM0.1) induce autophagic cell death of human
           neuronal cells
    • Abstract: Airborne nanoparticles PM0.1 (
      PubDate: 2016-04-15T01:51:59.577605-05:
      DOI: 10.1002/jat.3324
       
  • MicroRNA profiles in a monkey testicular injury model induced by
           testicular hyperthermia
    • Authors: Ken Sakurai; Kei Mikamoto, Makoto Shirai, Takuma Iguchi, Kazumi Ito, Wataru Takasaki, Kazuhiko Mori
      Abstract: To characterize microRNAs (miRNAs) involved in testicular toxicity in cynomolgus monkeys, miRNA profiles were investigated using next‐generation sequencing (NGS), microarray and reverse transcription‐quantitative real‐time‐PCR (RT‐qPCR) methods. First, to identify organ‐specific miRNAs, we compared the expression levels of miRNAs in the testes to those in representative organs (liver, heart, kidney, lung, spleen and small intestine) obtained from naïve mature male and female monkeys (n = 2/sex) using NGS analysis. Consequently, miR‐34c‐5p, miR‐202‐5p, miR‐449a and miR‐508‐3p were identified to be testicular‐specific miRNAs in cynomolgus monkeys. Next, we investigated miRNA profiles after testicular–hyperthermia (TH) treatment to determine which miRNAs are involved in testicular injury. In this experiment, mature male monkeys were divided into groups with or without TH‐treatment (n = 3/group) by immersion of the testes in a water bath at 43 °C for 30 min for 5 consecutive days. As a result, TH treatment induced testicular injury in all animals, which was characterized by decreased numbers of spermatocytes and spermatids. In a microarray analysis of the testis, 11 up‐regulated (>2.0 fold) and 13 down‐regulated (
      PubDate: 2016-04-12T21:45:55.640689-05:
      DOI: 10.1002/jat.3326
       
  • Accessing the molecular interactions of phthalates and their primary
           metabolites with the human pregnane X receptor using in silico profiling
    • Authors: M. K. Sarath Josh; S. Pradeep, Aparna K. Balan, M. N. Sreejith, Sailas Benjamin
      Abstract: Phthalates are known to cause endocrine disruption in humans and animals. Being lipophilic xenobiotic chemicals, phthalates from the surrounding environments can easily be absorbed into the biological system, thereby causing various health dysfunctions. This molecular docking study evaluates a variety of molecular interactions of 12 commonly used diphthalates and respective monophthalates onto the ligand binding domain (LBD) of the human pregnane X receptor (hPXR), a xenosensor, which would be beneficial for further in vitro and in vivo studies on hazardous phthalates. Out of 12 diphthalates and their monophthalates tested, diisodecyl phthalate (–9.16 kcal mol–1) showed more affinity toward hPXR whereas diisononyl phthalate (–8.77) and di(2‐ethyhexyl)phthalate (–8.56), the predominant plasticizers found in a variety of plastics and allied products, showed comparable binding scores with that of the control ligands such as hyperforine (–9.99) and dexamethasone (–7.36). In addition to the above diphthalates, some of their monophthalates (monoisodecyl phthalate, mono‐2‐etheylhexyl phthalate, etc.) also established similar interactions with certain crucial amino acids in the LBD, which led to higher G scores. In fact, bisphenol A, a well‐studied and proven endocrine disruptor, showed lesser G scores (–6.69) than certain phthalates. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-12T21:21:30.335434-05:
      DOI: 10.1002/jat.3321
       
  • Pyrazinamide induced hepatic injury in rats through inhibiting the
           PPARα pathway
    • Abstract: Pyrazinamide (PZA) causes serious hepatotoxicity, but little is known about the exact mechanism by which PZA induced liver injury. The peroxisome proliferator‐activated receptors alpha (PPARα) is highly expressed in the liver and modulates the intracellular lipidmetabolism. So far, the role of PPARα in the hepatotoxicity of PZA is unknown. In the present study, we described the hepatotoxic effects of PZA and the role of PPARα and its target genes in the downstream pathway including L‐Fabp, Lpl, Cpt‐1b, Acaa1, Apo‐A1 and Me1 in this process. We found PZA induced the liver lipid metabolism disorder and PPARα expressionwas down‐regulated which had a significant inverse correlation with liver injury degree. These changeswere ameliorated by fenofibrate, the co‐treatment that acts as a PPARα agonist. In contrast, short‐termstarvation significantly aggravated the severity of PZA‐induced liver injury. In conclusion, this study demonstrated the critical role played by PPARα in PZA‐induced hepatotoxicity and provided a better understanding of the molecular mechanisms underlying PZA‐induced liver injury. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-12T21:16:46.631941-05:
      DOI: 10.1002/jat.3319
       
  • Polymatin A from Smallanthus macroscyphus leaves: A safe and promising
           antidiabetic compound
    • Abstract: Smallanthus macroscyphus is an herb native to South America whose leaves are a source of antidiabetic compounds, although complete information about their safe use is not available yet. This study was developed to evaluate the toxicity profile of both 10% decoction and the sesquiterpene lactone polymatin A from S. macroscyphus leaves through in vitro cytotoxicity assays and in vivo subchronic oral toxicity. Cell viability of Hep‐G2, COS1, CHO‐K1 and Vero cell lines decreased in a concentration‐dependent manner when cells were incubated with 0.4–200 μg ml–1 of dry extract or 0.12–60 μg ml–1 of polymatin A. In subchronic studies, decoction was orally administered to Wistar rats for 90 days at daily doses of 70, 140 and 280 mg kg–1 of dry extract, whereas polymatin A was administered in the same way at doses of 7, 14 and 28 mg kg–1. No toxicity signs or deaths were observed. There were no changes in the behavior, body or organ weights, hematological, biochemical or urine parameters of the rats. No histopathological lesions were observed in the examined organs. The results indicate that the 10% decoction and polymatin A from S. macroscyphus leaves may be considered as non‐toxic substances at a wide range of doses, including the effective hypoglycemic dose. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-07T01:15:44.738352-05:
      DOI: 10.1002/jat.3312
       
  • Perfluorooctane sulfonate (PFOS) impairs the proliferation of C17.2 neural
           stem cells via the downregulation of
           GSK‐3β/β‐catenin signaling
    • Authors: Xuan Dong; Jianbin Yang, Xiaoke Nie, Jing Xiao, Shengyang Jiang
      Abstract: The neurotoxic effects of perfluorooctane sulfonate (PFOS) have attracted significant research attention in recent years. In the present study, we investigated the impact of PFOS exposure on the physiology of neural stem cells (NSCs) in vitro. We showed that PFOS exposure markedly attenuated the proliferation of C17.2 neural stem cells in both dose‐ and time‐dependent manners. Additionally, we found that PFOS decreased Ser9 phosphorylation of glycogen synthase kinase‐3β (pSer9‐GSK‐3β), leading to the activation of GSK‐3β and resultant downregulation of cellular β‐catenin. Furthermore, blockage of GSK‐3β with lithium chloride significantly attenuated both the PFOS‐induced downregulation of GSK‐3β/β‐catenin and the proliferative impairment of C17.2 cells. Notably, the expression of various downstream targets was altered accordingly, such as c‐myc, cyclin D1 and survivin. In conclusion, the present study demonstrated that PFOS decreased the proliferation of C17.2 cells via the negative modulation of the GSK‐3β/β‐catenin pathway. We present the potential mechanisms underlying the PFOS‐induced toxic effects on NSCs to provide novel insights into the neurotoxic mechanism of PFOS. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-28T06:15:37.369126-05:
      DOI: 10.1002/jat.3320
       
  • Arsenic inhibits mast cell degranulation via suppression of early tyrosine
           phosphorylation events
    • Authors: Juyoung Shim; Rachel H. Kennedy, Lisa M. Weatherly, Lee M. Hutchinson, Jonathan H. Pelletier, Hina N. Hashmi, Kayla Blais, Alejandro Velez, Julie A. Gosse
      Abstract: Exposure to arsenic is a global health concern. We previously documented an inhibitory effect of inorganic Arsenite on IgE‐mediated degranulation of RBL‐2H3 mast cells (Hutchinson et al., 2011; J. Appl. Toxicol. 31: 231–241). Mast cells are tissue‐resident cells that are positioned at the host–environment interface, thereby serving vital roles in many physiological processes and disease states, in addition to their well‐known roles in allergy and asthma. Upon activation, mast cells secrete several mediators from cytoplasmic granules, in degranulation. The present study is an investigation of Arsenite's molecular target(s) in the degranulation pathway. Here, we report that arsenic does not affect degranulation stimulated by either the Ca2+ ionophore A23187 or thapsigargin, which both bypass early signaling events. Arsenic also does not alter degranulation initiated by another non‐IgE‐mediated mast cell stimulant, the G‐protein activator compound 48/80. However, arsenic inhibits Ca2+ influx into antigen‐activated mast cells. These results indicate that the target of arsenic in the degranulation pathway is upstream of the Ca2+ influx. Phospho‐Syk and phospho‐p85 phosphoinositide 3‐kinase enzyme‐linked immunosorbent assays data show that arsenic inhibits early phosphorylation events. Taken together, this evidence indicates that the mechanism underlying arsenic inhibition of mast cell degranulation occurs at the early tyrosine phosphorylation steps in the degranulation pathway. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-28T06:10:38.664742-05:
      DOI: 10.1002/jat.3300
       
  • Danio rerio ABC transporter genes abcb3 and abcb7 play a protecting role
           against metal contamination
    • Abstract: ATP‐binding cassette (ABC) proteins are efflux transporters and some of them are involved in xenobiotic detoxification. The involvement of four zebrafish ABC transporters in cadmium, zinc and mercury detoxification was characterized in a metal hypersensitive mutant of Escherichia coli. The E. coli tolC mutant expressing ABCB3 or ABCB7 transporters exhibited higher survival ratios and lower metal accumulation under a metal exposure condition than the controls. For instance, in the presence of 8 and 10 μM of HgCl2, the survival ratios of bacteria expressing ABCB3 were four and six‐times higher than the control whereas the mercury concentrations were 2.5 and 2‐times lower than in the control. This work provides new data on the function of zebrafish ABCB3 and ABCB7 transporters and highlights their significance in metal detoxification. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-28T06:05:52.841222-05:
      DOI: 10.1002/jat.3313
       
  • Triclosan is a mitochondrial uncoupler in live zebrafish
    • Authors: Juyoung Shim; Lisa M. Weatherly, Richard H. Luc, Maxwell T. Dorman, Andy Neilson, Ryan Ng, Carol H. Kim, Paul J. Millard, Julie A. Gosse
      Abstract: Triclosan (TCS) is a synthetic antimicrobial agent used in many consumer goods at millimolar concentrations. As a result of exposure, TCS has been detected widely in humans. We have recently discovered that TCS is a proton ionophore mitochondrial uncoupler in multiple types of living cells. Here, we present novel data indicating that TCS is also a mitochondrial uncoupler in a living organism: 24‐hour post‐fertilization (hpf) zebrafish embryos. These experiments were conducted using a Seahorse Bioscience XFe 96 Extracellular Flux Analyzer modified for bidirectional temperature control, using the XF96 spheroid plate to position and measure one zebrafish embryo per well. Using this method, after acute exposure to TCS, the basal oxygen consumption rate (OCR) increases, without a decrease in survival or heartbeat rate. TCS also decreases ATP‐linked respiration and spare respiratory capacity and increases proton leak: all indicators of mitochondrial uncoupling. Our data indicate, that TCS is a mitochondrial uncoupler in vivo, which should be taken into consideration when assessing the toxicity and/or pharmaceutical uses of TCS. This is the first example of usage of a Seahorse Extracellular Flux Analyzer to measure bioenergetic flux of a single zebrafish embryo per well in a 96‐well assay format. The method developed in this study provides a high‐throughput tool to identify previously unknown mitochondrial uncouplers in a living organism. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-28T06:00:41.219016-05:
      DOI: 10.1002/jat.3311
       
  • The neurotoxicity of DE‐71: effects on neural development and
           impairment of serotonergic signaling in zebrafish larvae
    • Authors: Xianfeng Wang; Lihua Yang, Qiangwei Wang, Yongyong Guo, Na Li, Mei Ma, Bingsheng Zhou
      Abstract: The underlying mechanism of polybrominated diphenyl ether (PBDE)‐induced neurotoxicity is still a major concern due to its ubiquitous nature and persistence. Here, zebrafish embryos (2 h postfertilization, hpf) were exposed to different concentrations of the commercial PBDE mixture DE‐71 (0–100 µg l–1) until 120 hpf, and the impact on neural development and serotonergic system was investigated. The in vivo results revealed significantly reduced transcription of genes involved in neurogenesis (fgf8, shha, wnt1), and contents of proteins in neuronal morphogenesis (myelin basic protein, synapsin IIa), suggesting an impairment of neural development in zebrafish embryos. Further results demonstrated a reduction of 5‐hydroxytryptamine neuron and a dose‐dependent decrease of whole‐body serotonin levels, as well as the transcription of genes involved in serotonergic synthesis (tph1, tph2, trhr) and neurotransmission (serta/b, htr1aa/b). In addition, we predicted possible targets of PBDEs by molecular docking, and the results indicated that PBDE congeners showed high binding affinities with fibroblast growth factor 8 other than SHH and HTR1B. Taken together, this study demonstrated that PBDE exposure during embryogenesis could damage neural development and cause impairment of the serotonergic system as secondary effects in the zebrafish larvae. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-22T04:45:38.166693-05:
      DOI: 10.1002/jat.3322
       
  • Let‐7a modulates particulate matter (≤
           2.5 μm)‐induced oxidative stress and injury in human
           airway epithelial cells by targeting arginase 2
    • Authors: Lei Song; Dan Li, Yue Gu, Xiaoping Li, Liping Peng
      Abstract: Epidemiological studies show that particulate matter (PM) with an aerodynamic diameter ≤ 2.5 μm (PM2.5) is associated with cardiorespiratory diseases via the induction of excessive oxidative stress. However, the precise mechanism underlying PM2.5‐mediated oxidative stress injury has not been fully elucidated. Accumulating evidence has indicated the microRNA let‐7 family might play a role in PM‐mediated pathological processes. In this study, we investigated the role of let‐7a in oxidative stress and cell injury in human bronchial epithelial BEAS2B (B2B) cells after PM2.5 exposure. The let‐7a level was the most significantly decreased in B2B cells after PM2.5 exposure. The overexpression of let‐7a suppressed intracellular reactive oxygen species levels and the percentage of apoptotic cells after PM2.5 exposure, while the let‐7a level decreased arginase 2 (ARG2) mRNA and protein levels in B2B cells by directly targeting the ARG2 3′‐untranslated region. ARG2 expression was upregulated in B2B cells during PM2.5 treatment, and ARG2 knockdown could remarkably reduce oxidative stress and cellular injury. Moreover, its restoration could abrogate the protective effects of let‐7a against PM2.5‐induced injury. In conclusion, let‐7a decreases and ARG2 increases resulting from PM2.5 exposure may exacerbate oxidative stress, cell injury and apoptosis of B2B cells. The let‐7a/ARG2 axis is a likely therapeutic target for PM2.5‐induced airway epithelial injury. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-15T05:50:53.102023-05:
      DOI: 10.1002/jat.3309
       
  • Different mechanisms of action of 2, 2’, 4,
           4’‐tetrabromodiphenyl ether (BDE‐47) and its metabolites
           (5‐OH‐BDE‐47 and 6‐OH‐BDE‐47) on cell
           proliferation in OVCAR‐3 ovarian cancer cells and MCF‐7 breast
           cancer cells
    • Abstract: Data concerning the possible action of polybrominated diphenyl ethers (PBDEs) in hormone‐dependent cancer are scarce. Some data showed that PBDEs may directly affect breast cancer cells formation and only one research showed increased proliferation of the OVCAR‐3 cells, but the results are ambiguous and the mechanisms are not clear. There is growing evidence that not only parent compounds but also its metabolites may be involved in cancer development. The present study was, therefore, designed to determine the effect of BDE‐47 and its metabolites (2.5 to 50 ng ml–1) on proliferation (BrdU), cell‐cycle genes (real‐time PCR) and protein expression (Western blot), protein expression of oestrogen receptors (α β), extracellular signal‐regulated kinases 1 and 2 (ERK1/2) and protein kinase Cα (PKCα) in OVCAR‐3 ovarian and MCF‐7 breast cancer cells. In OVCAR‐3 cells, the parent compound stimulated cell proliferation by activating CDK1, CDK7, E2F1 and E2F2. Independent of time of exposure, BDE‐47 had no effect on ERα and ERβ protein expression and ERK1/2 and PKCα phosphorylation. Metabolites had no effect on cell proliferation but increased both ERs protein expression and ERK1/2 and PKCα phosphorylation. In MCF‐7 cells, the parent compound displayed no effect on cell proliferation but decreased ERα and increased ERβ protein expression with concomitant induction of PKCα phosphorylation. Both metabolites increased MCF‐7 cell proliferation, ERK1/2 and PKCα phosphorylation and decreased ERα and ERβ protein expression.We suggest that studies concerning PBDEs with fewer bromine atoms should be continued to understand environmental links to different hormone‐dependent cancers. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-14T07:48:03.50754-05:0
      DOI: 10.1002/jat.3316
       
  • 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin exposure influence
           the expression of glutamate transporter GLT‐1 in C6 glioma cells via
           the Ca2+/protein kinase C pathway
    • Authors: Jianya Zhao; Yan Zhang, Jianmei Zhao, Cheng Wang, Jiamin Mao, Ting Li, Xiaoke Wang, Xiaoke Nie, Shengyang Jiang, Qiyun Wu
      Abstract: The widespread environmental contaminant, 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD), is considered one of the most toxic dioxin‐like compounds. Although epidemiological studies have shown that TCDD exposure is linked to some neurological and neurophysiological disorders, the underlying mechanism of TCDD‐mediated neurotoxicity has remained unclear. Astrocytes are the most abundant cells in the nervous systems, and are recognized as the important mediators of normal brain functions as well as neurological, neurodevelopmental and neurodegenerative brain diseases. In this study, we investigated the role of TCDD in regulating the expression of glutamate transporter GLT‐1 in astrocytes. TCDD, at concentrations of 0.1–100 nm, had no significantly harmful effect on the viability of C6 glioma cells. However, the expression of GLT‐1 in C6 glioma cells was downregulated in a dose‐ and time‐dependent manner. TCDD also caused activation of protein kinase C (PKC), as TCDD induced translocation of the PKC from the cytoplasm or perinuclear to the membrane. The translocation of PKC was inhibited by one Ca2+ blocker, nifedipine, suggesting that the effects are triggered by the initial elevated intracellular concentration of free Ca2+. Finally, we showed that inhibition of the PKC activity reverses the TCDD‐triggered reduction of GLT‐1. In summary, our results suggested that TCDD exposure could downregulate the expression of GLT‐1 in C6 via Ca2+/PKC pathway. The downregulation of GLT‐1 might participate in TCDD‐mediated neurotoxicity. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-14T07:45:58.97007-05:0
      DOI: 10.1002/jat.3294
       
  • Neuropathy target esterase in mouse whole blood as a biomarker of exposure
           to neuropathic organophosphorus compounds
    • Authors: Galina F. Makhaeva; Elena V. Rudakova, Larisa V. Sigolaeva, Ilya N. Kurochkin, Rudy J. Richardson
      Abstract: The adult hen is the standard animal model for testing organophosphorus (OP) compounds for organophosphorus compound‐induced delayed neurotoxicity (OPIDN). Recently, we developed a mouse model for biochemical assessment of the neuropathic potential of OP compounds based on brain neuropathy target esterase (NTE) and acetylcholinesterase (AChE) inhibition. We carried out the present work to further develop the mouse model by testing the hypothesis that whole blood NTE inhibition could be used as a biochemical marker for exposure to neuropathic OP compounds. Because brain NTE and AChE inhibition are biomarkers of OPIDN and acute cholinergic toxicity, respectively, we compared NTE and AChE 20‐min IC50 values as well as ED50 values 1 h after single intraperitoneal (i.p.) injections of increasing doses of two neuropathic OP compounds that differed in acute toxicity potency. We found good agreement between the brain and blood for in vitro sensitivity of each enzyme as well for the ratios IC50(AChE)/IC50(NTE). Both OP compounds inhibited AChE and NTE in the mouse brain and blood dose‐dependently, and brain and blood inhibitions in vivo were well correlated for each enzyme. For both OP compounds, the ratio ED50(AChE)/ED50(NTE) in blood corresponded to that in the brain despite the somewhat higher sensitivity of blood enzymes. Thus, our results indicate that mouse blood NTE could serve as a biomarker of exposure to neuropathic OP compounds. Moreover, the data suggest that relative inhibition of blood NTE and AChE provide a way to assess the likelihood that OP compound exposure in a susceptible species would produce cholinergic and/or delayed neuropathic effects. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-11T04:25:23.822139-05:
      DOI: 10.1002/jat.3305
       
  • Silver nanoparticles induce pro‐inflammatory gene expression and
           inflammasome activation in human monocytes
    • Authors: A. Murphy; A. Casey, G. Byrne, G. Chambers, O. Howe
      Abstract: A complete cytotoxic profile of exposure to silver (AgNP) nanoparticles investigating their biological effects on the innate immune response of circulating white blood cells is required to form a complete understanding of the risk posed. This was explored by measuring AgNP‐stimulated gene expression of the pro‐inflammatory cytokines interleukin‐1 (IL‐1), interleukin‐6 (IL‐6) and tumour necrosis factor‐alpha (TNF‐α) in THP‐1 monocytes. A further study, on human monocytes extracted from a cohort of blood samples, was carried out to compare with the AgNP immune response in THP‐1 cells along with the detection of pro‐IL‐1β which is a key mediator of the inflammasome complex. The aims of the study were to clearly demonstrate that AgNP can significantly up‐regulate pro‐inflammatory cytokine gene expression of IL‐1, IL‐6 and TNF‐α in both THP‐1 cells and primary blood monocytes thus indicating a rapid response to AgNP in circulation. Furthermore, a role for the inflammasome in AgNP response was indicated by pro‐IL‐1β cleavage and release. These results highlight the potential inflammatory effects of AgNP exposure and the responses evoked should be considered with respect to the potential harm that exposure may cause. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-10T05:13:09.077377-05:
      DOI: 10.1002/jat.3315
       
  • Dose site reactions and related findings after vaccine administration in
           safety studies
    • Authors: Paul Baldrick
      Abstract: Potential new human vaccines undergo toxicology testing to evaluate local reactogenicity and systemic toxicity. A review of 30 recently published and in‐house repeat dose toxicity studies with a variety of vaccines was performed. Species tested were generally rat or rabbit, usually by intramuscular (although occasionally subcutaneous) injection. Results showed no unexpected findings indicating vaccine toxicity, but classic signs of enhanced acute and/or chronic inflammation at the dose site compared with that seen in injected control animals, often accompanied by changes in draining lymph nodes and the spleen (lymphoid hyperplasia and/or increased weight). Other associated signs of a response to vaccine dosing were altered clinical pathology parameters (commonly raised blood neutrophil count and altered globulin level). No obvious difference in dose site or systemic reaction was seen across vaccine, species or the dose route used. A non‐dose recovery period of 2 to 4 weeks was sufficient to show evidence of reversibility of dose site effects. Injection site, lymphoid tissue and clinical pathological changes can be interpreted as related to an expected reaction after vaccine dosing, with generation of an immune response largely as a result of the presence of adjuvant, although direct vaccine antigen involvement was also occasionally demonstrated by the presence of a slightly increased inflammatory response seen over adjuvant treatment only. Overall, the need for toxicity testing of vaccines is in line with current regulatory guideline requirements and has proven to be a valuable part of the safety evaluation process prior to human use. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-10T05:05:30.743776-05:
      DOI: 10.1002/jat.3314
       
  • Phenotypic and biomarker evaluation of zebrafish larvae as an alternative
           model to predict mammalian hepatotoxicity
    • Authors: Sandra Verstraelen; Bernard Peers, Walid Maho, Karen Hollanders, Sylvie Remy, Pascale Berckmans, Adrian Covaci, Hilda Witters
      Abstract: Zebrafish phenotypic assays have shown promise to assess human hepatotoxicity, though scoring of liver morphology remains subjective and difficult to standardize. Liver toxicity in zebrafish larvae at 5 days was assessed using gene expression as the biomarker approach, complementary to phenotypic analysis and analytical data on compound uptake. This approach aimed to contribute to improved hepatotoxicity prediction, with the goal of identifying biomarker(s) as a step towards the development of transgenic models for prioritization. Morphological effects of hepatotoxic compounds (acetaminophen, amiodarone, coumarin, methapyrilene and myclobutanil) and saccharin as the negative control were assessed after exposure in zebrafish larvae. The hepatotoxic compounds induced the expected zebrafish liver degeneration or changes in size, whereas saccharin did not have any phenotypic adverse effect. Analytical methods based on liquid chromatography–mass spectrometry were optimized to measure stability of selected compounds in exposure medium and internal concentration in larvae. All compounds were stable, except amiodarone for which precipitation was observed. There was a wide variation between the levels of compound in the zebrafish larvae with a higher uptake of amiodarone, methapyrilene and myclobutanil. Detection of hepatocyte markers (CP, CYP3A65, GC and TF) was accomplished by in situ hybridization of larvae to coumarin and myclobutanil and confirmed by real‐time reverse transcription–quantitative polymerase chain reaction. Experiments showed decreased expression of all markers. Next, other liver‐specific biomarkers (i.e. FABP10a and NR1H4) and apoptosis (i.e. CASP‐3 A and TP53) or cytochrome P450‐related (CYP2K19) and oxidoreductase activity‐related (ZGC163022) genes, were screened. Links between basic mechanisms of liver injury and results of biomarker responses are described. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-04T15:06:09.128391-05:
      DOI: 10.1002/jat.3288
       
  • Optimization of an air–liquid interface exposure system for
           assessing toxicity of airborne nanoparticles
    • Abstract: The use of refined toxicological methods is currently needed for characterizing the risks of airborne nanoparticles (NPs) to human health. To mimic pulmonary exposure, we have developed an air–liquid interface (ALI) exposure system for direct deposition of airborne NPs on to lung cell cultures. Compared to traditional submerged systems, this allows more realistic exposure conditions for characterizing toxicological effects induced by airborne NPs. The purpose of this study was to investigate how the deposition of silver NPs (AgNPs) is affected by different conditions of the ALI system. Additionally, the viability and metabolic activity of A549 cells was studied following AgNP exposure. Particle deposition increased markedly with increasing aerosol flow rate and electrostatic field strength. The highest amount of deposited particles (2.2 μg cm–2) at cell‐free conditions following 2 h exposure was observed for the highest flow rate (390 ml min–1) and the strongest electrostatic field (±2 kV). This was estimated corresponding to deposition efficiency of 94%. Cell viability was not affected after 2 h exposure to clean air in the ALI system. Cells exposed to AgNPs (0.45 and 0.74 μg cm–2) showed significantly (P < 0.05) reduced metabolic activities (64 and 46%, respectively). Our study shows that the ALI exposure system can be used for generating conditions that were more realistic for in vitro exposures, which enables improved mechanistic and toxicological studies of NPs in contact with human lung cells.Copyright © 2016 The
      Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.
      PubDate: 2016-03-03T04:41:36.223457-05:
      DOI: 10.1002/jat.3304
       
  • Evaluation of the effects of deltamethrin on the fetal rat testis
    • Abstract: Pregnant Sprague–Dawley rats were administered deltamethrin, at doses 0.1, 1, 5 or 10 mg kg−1 day−1, or di‐n‐hexyl phthalate (DnHP) (250 mg kg−1 day−1), by gavage, from gestational day 13 to 19. Maternal toxicity was observed at 10 mg kg−1 day−1, as evidenced by transient clinical signs of neurotoxicity and reductions in body weight, body weight gain and corrected weight gain. Deltamethrin had no statistically significant effect on the incidence of post‐implantation loss, fetal weight or anogenital distance in the male fetuses. Unlike DnHP, deltamethrin induced no changes in the expression of several genes involved in cholesterol transport or in the steroid synthesis pathway in the testes of gestational day 19.5 male fetuses (SRB1, StAR, P450scc, 3βHSD, P450 17 A1, 17βHSD). Fetal testicular levels of P450scc and P450 17 A1 protein were also unaffected by deltamethrin. No statistically significant differences were observed in the ex vivo fetal testicular production of testosterone and androstenedione after deltamethrin exposure, whereas DnHP markedly reduced these parameters. The deltamethrin metabolite, 3‐phenoxybenzoic acid, was detected in amniotic fluid. In summary, our results demonstrate that in utero exposure to deltamethrin during the period of sexual differentiation had no significant effect on the testosterone synthesis pathway in the male rat fetus up to a maternal toxic dose. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-02T09:56:03.645544-05:
      DOI: 10.1002/jat.3310
       
  • Early metabolomics changes in heart and plasma during chronic doxorubicin
           treatment in B6C3F1 mice
    • Abstract: The present study aimed to identify molecular markers of early stages of cardiotoxicity induced by a potent chemotherapeutic agent, doxorubicin (DOX). Male B6C3F1 mice were dosed with 3 mg kg−1 DOX or saline via tail vein weekly for 2, 3, 4, 6 or 8 weeks (cumulative DOX doses of 6, 9, 12, 18 or 24 mg kg−1, respectively) and euthanized a week after the last dose. Mass spectrometry‐based and nuclear magnetic resonance spectrometry‐based metabolic profiling were employed to identify initial biomarkers of cardiotoxicity before myocardial injury and cardiac pathology, which were not noted until after the 18 and 24 mg kg−1 cumulative doses, respectively. After a cumulative dose of 6 mg kg−1, 18 amino acids and four biogenic amines (acetylornithine, kynurenine, putrescine and serotonin) were significantly increased in cardiac tissue; 16 amino acids and two biogenic amines (acetylornithine and hydroxyproline) were significantly altered in plasma. In addition, 16 acylcarnitines were significantly increased in plasma and five were significantly decreased in cardiac tissue compared to saline‐treated controls. Plasma lactate and succinate, involved in the Krebs cycle, were significantly altered after a cumulative dose of 6 mg kg−1. A few metabolites remained altered at higher cumulative DOX doses, which could partly indicate a transition from injury processes at 2 weeks to repair processes with additional injury happening concurrently before myocardial injury at 8 weeks. These altered metabolic profiles in mouse heart and plasma during the initial stages of injury progression due to DOX treatment may suggest these metabolites as candidate early biomarkers of cardiotoxicity. Published 2016. This article is a U.S. Government work and is in the public domain in the USA
      PubDate: 2016-03-02T09:47:14.1603-05:00
      DOI: 10.1002/jat.3307
       
  • Involvement of calcium/calmodulin‐dependent protein kinase II in
           methamphetamine‐induced neural damage
    • Authors: Xufeng Chen; Jingjing Xing, Lei Jiang, Wenyi Qian, Yixin Wang, Hao Sun, Yu Wang, Hang Xiao, Jun Wang, Jinsong Zhang
      Abstract: Methamphetamine (METH), an illicit drug, is widely abused in many parts of the world. Mounting evidence shows that METH exposure contributes to neurotoxicity, particularly for the monoaminergic neurons. However, to date, only a few studies have tried to unravel the mechanisms involved in METH‐induced non‐monoaminergic neural damage. Therefore, in the present study, we tried to explore the mechanisms for METH‐induced neural damage in cortical neurons. Our results showed that METH significantly increased intracellular [Ca2+]i in Ca2+‐containing solution rather than Ca2+‐free solution. Moreover, METH also upregulated calmodulin (CaM) expression and activated CaM‐dependent protein kinase II (CaMKII). Significantly, METH‐induced neural damage can be partially retarded by CaM antagonist W7 as well as CaMKII blocker KN93. In addition, L‐type Ca2+ channel was also proved to be involved in METH‐induced cell damage, as nifedipine, the L‐type Ca2+ channel‐specific inhibitor, markedly attenuated METH‐induced neural damage. Collectively, our results suggest that Ca2+‐CaM‐CaMKII is involved in METH‐mediated neurotoxicity, and it might suggest a potential target for the development of therapeutic strategies for METH abuse. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-29T06:51:15.609942-05:
      DOI: 10.1002/jat.3301
       
  • Oxidative stress and lung pathology following geogenic dust exposure
    • Authors: M. Leetham; J. DeWitt, B. Buck, D. Goossens, Y. Teng, J. Pollard, B. McLaurin, R. Gerads, D. Keil
      Abstract: This study was designed to evaluate markers of systemic oxidative stress and lung histopathology following subacute exposure to geogenic dust with varying heavy metal content collected from a natural setting prone to wind erosion and used heavily for off‐road vehicle recreation. Adult female B6C3F1 mice were exposed to several concentrations of dust collected from seven different types of surfaces at the Nellis Dunes Recreation Area in Clark County, Nevada, designated here as CBN 1‐7. Dust representing each of the seven surface types, with an average median diameter of 4.2 μm, was selected and administered via oropharyngeal aspiration to mice at concentrations from 0.01 to 100 mg of dust kg–1 of body weight. Exposures were given four times spaced a week apart over a 28 day period to mimic a month of weekend exposures. Lung pathology was evaluated while plasma markers of oxidative stress included levels of reactive oxygen and nitrogen species, superoxide dismutase, total antioxidant capacity and total glutathione. Overall, results of these assays to evaluate markers of oxidative stress indicate that no single CBN surface type was able to consistently induce markers of systemic oxidative stress at a particular dose or in a dose–response manner. All surface types were able to induce some level of lung inflammation, typically at the highest exposure levels. These data suggest that dust from the Nellis Dunes Recreation Area may present a potential health risk, but additional studies are necessary to characterize the full extent of health risks to humans. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-29T06:29:37.960919-05:
      DOI: 10.1002/jat.3297
       
  • Development of a quantitative morphological assessment of
           toxicant‐treated zebrafish larvae using brightfield imaging and
           high‐content analysis
    • Authors: Samantha Deal; John Wambaugh, Richard Judson, Shad Mosher, Nick Radio, Keith Houck, Stephanie Padilla
      Abstract: One of the rate‐limiting procedures in a developmental zebrafish screen is the morphological assessment of each larva. Most researchers opt for a time‐consuming, structured visual assessment by trained human observer(s). The present studies were designed to develop a more objective, accurate and rapid method for screening zebrafish for dysmorphology. Instead of the very detailed human assessment, we have developed the computational malformation index, which combines the use of high‐content imaging with a very brief human visual assessment. Each larva was quickly assessed by a human observer (basic visual assessment), killed, fixed and assessed for dysmorphology with the Zebratox V4 BioApplication using the Cellomics® ArrayScan® VTI high‐content image analysis platform. The basic visual assessment adds in‐life parameters, and the high‐content analysis assesses each individual larva for various features (total area, width, spine length, head–tail length, length–width ratio, perimeter–area ratio). In developing the computational malformation index, a training set of hundreds of embryos treated with hundreds of chemicals were visually assessed using the basic or detailed method. In the second phase, we assessed both the stability of these high‐content measurements and its performance using a test set of zebrafish treated with a dose range of two reference chemicals (trans‐retinoic acid or cadmium). We found the measures were stable for at least 1 week and comparison of these automated measures to detailed visual inspection of the larvae showed excellent congruence. Our computational malformation index provides an objective manner for rapid phenotypic brightfield assessment of individual larva in a developmental zebrafish assay. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-29T04:58:40.169528-05:
      DOI: 10.1002/jat.3290
       
  • Low‐dose benzo[a]pyrene aggravates allergic airway inflammation in
           mice
    • Abstract: Benzo[a]pyrene (BaP) reportedly has mutagenic and adjuvant activities. We aimed to determine the effects of low‐dose BaP administration on allergic airway inflammation and mediastinal lymph node (MLN) cell activation/proliferation in mice. Male C3H/HeJ mice were intratracheally administered ovalbumin (OVA) every 2 weeks and/or BaP (0, 0.05, 1 and 20 pmol per animal per week) once per week for 6 weeks. The cellular profile of bronchoalveolar lavage (BAL) fluid, histological changes, inflammatory cytokines/chemokines in the lungs, OVA‐specific immunoglobulin (Ig) in serum and MLN cell activation/proliferation were examined. BaP administration of 20 pmol with OVA enhanced neutrophil and macrophage accumulation in the lungs. Compared with OVA administration, BaP administration with OVA tended to enhance pulmonary eosinophilia and goblet cell hyperplasia. Furthermore, it increased the levels of interleukin (IL)‐5, IL‐13, IL‐33, monocyte chemoattractant protein‐1 and eotaxin in the lungs, and OVA‐specific IgG1 in serum, although not dose‐dependently. Compared with the vehicle group, IL‐6 and tumor necrosis factor‐alpha levels were higher in the OVA + 1 pmol BaP group and IL‐12 production was higher in the OVA + 20 pmol BaP group. Ex vivo studies showed that co‐exposure to OVA and BaP activated the MHC class II and CD86 expression in MLN cells. Exposure to BaP with OVA increased IL‐4, IL‐5 and interferon gamma levels in culture supernatants of OVA‐re‐stimulated MLN cells. In conclusion, low‐dose BaP can, at least in part, enhance allergic airway inflammation by facilitating Th2 responses and activating MLN cells; a high BaP dose may contribute to activating both Th1 and Th2 responses. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-25T06:38:11.361478-05:
      DOI: 10.1002/jat.3308
       
  • Differential cytotoxicity of copper ferrite nanoparticles in different
           human cells
    • Abstract: Copper ferrite nanoparticles (NPs) have the potential to be applied in biomedical fields such as cell labeling and hyperthermia. However, there is a lack of information concerning the toxicity of copper ferrite NPs. We explored the cytotoxic potential of copper ferrite NPs in human lung (A549) and liver (HepG2) cells. Copper ferrite NPs were crystalline and almost spherically shaped with an average diameter of 35 nm. Copper ferrite NPs induced dose‐dependent cytotoxicity in both types of cells, evident by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazoliumbromide and neutral red uptake assays. However, we observed a quite different susceptibility in the two kinds of cells regarding toxicity of copper ferrite NPs. Particularly, A549 cells showed higher susceptibility against copper ferrite NP exposure than those of HepG2 cells. Loss of mitochondrial membrane potential due to copper ferrite NP exposure was observed. The mRNA level as well as activity of caspase‐3 enzyme was higher in cells exposed to copper ferrite NPs. Cellular redox status was disturbed as indicated by induction of reactive oxygen species (oxidant) generation and depletion of the glutathione (antioxidant) level. Moreover, cytotoxicity induced by copper ferrite NPs was efficiently prevented by N‐acetylcysteine treatment, which suggests that reactive oxygen species generation might be one of the possible mechanisms of cytotoxicity caused by copper ferrite NPs. To the best of our knowledge, this is the first report showing the cytotoxic potential of copper ferrite NPs in human cells. This study warrants further investigation to explore the mechanisms of differential toxicity of copper ferrite NPs in different types of cells. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-25T06:25:05.26449-05:0
      DOI: 10.1002/jat.3299
       
  • Neverland regulates embryonic moltings through the regulation of
           ecdysteroid synthesis in the water flea Daphnia magna, and may thus act as
           a target for chemical disruption of molting
    • Authors: Eri Sumiya; Yukiko Ogino, Kenji Toyota, Hitoshi Miyakawa, Shinichi Miyagawa, Taisen Iguchi
      Abstract: Embryo development in arthropods is accompanied by a series of moltings. A cladoceran crustacean Daphnia magna molts three times before reaching first instar neonate during embryogenesis. Previous studies argued ecdysteroids might regulate D. magna embryogenesis. However, no direct evidence between innate ecdysteroids fluctuation and functions has been forthcoming. Recently, we identified genes involved in ecdysteroid synthesis called, neverland (neverland1 and neverland 2) and shade and in the ecdysteroid degradation (Cyp18a1). To understand the physiological roles of ecdysteroids in D. magna embryos, we performed expression and functional analyzes of those genes. Examining innate ecdysteroids titer during embryogenesis showed two surges of ecdysteroids titer at 41 and 61 h after oviposition. The first and second embryonic moltings occurred at each ecdysteroid surge. Expression of neverland1 and shade began to increase before the first peak in ecdysteroid. Knockdown of neverland1 or shade by RNAi technique caused defects in embryonic moltings and subsequent development. The ecdysteroids titer seemingly decreased in nvd1‐knowckdown embryos. Knockdown of Cyp18a1 resulted in early embryonic lethality before the first molting. Our in situ hybridization analysis revealed that nvd1 was prominently expressed in embryonic gut epithelium suggesting the site for an initial step of ecdysteroidgenesis, a conversion of cholesterol to 7‐dehydrocholesterol and possibly for ecdysone production. Taken together, de novo ecdysteroid synthesis by nvd1 in the gut epithelial cells stimulates molting, which is indispensable for D. magna embryo development. These findings identify neverland as a possible target for chemicals, including various pesticides that are known to disrupt molting, development and reproduction. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-22T02:04:51.919418-05:
      DOI: 10.1002/jat.3306
       
  • Cytotoxicity of various chemicals and mycotoxins in fresh primary duck
           embryonic fibroblasts: a comparison to HepG2 cells
    • Authors: Xi Chen; Rhonda Murdoch, Daniel J. Shafer, Kolapo M. Ajuwon, Todd J. Applegate
      Abstract: To screen cost‐effectively the overall toxicity of a sample, particularly in the case of food and feed ingredient quality control, a sensitive bioassay is necessary. With the wide variety of cytotoxicity assays, performance comparison between assays using different cells has become of interest. Fresh primary duck embryonic fibroblasts (DEF) were hypothesized to be a sensitive tool for in vitro cytotoxicity screening; cell viability of DEF in response to various cytotoxins was determined and compared with response of HepG2 cells. The IC50 values obtained by the alamar blue assay in the DEF cells had a high correlation (R2 = 0.96) with those obtained in HepG2 cells. Within the same toxin, primary DEF yielded significantly lower IC50 values than that obtained from HepG2 cells using the MTT and alamar blue assay. Additionally, primary DEF responded to all mycotoxins tested using the alamar blue assay, while HepG2 was less sensitive, particularly at short exposure times. The estimated IC50 for aflatoxin B1, fumonisins B1 and deoxynivalenol in DEF after 72 h incubation were 3.69, 4.19 and 1.26 μg ml–1, respectively. Results from the current study suggest that primary DEF are more sensitive to cytotoxins and mycotoxins compared to HepG2, and thus may have great potential as an effective tool for cytotoxicity assessment. The question remains whether in vitro IC50 values can accurately predict in vivo toxicity; however, the current study accentuates the need for further attention to identify sensitive cell models for in vitro cytotoxicity screening and subsequent exploration of species‐specific prediction models for in vivo toxicity. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-18T05:45:38.333209-05:
      DOI: 10.1002/jat.3298
       
  • Cannabis effects on driving longitudinal control with and without alcohol
    • Authors: Rebecca L. Hartman; Timothy L. Brown, Gary Milavetz, Andrew Spurgin, Russell S. Pierce, David A. Gorelick, Gary Gaffney, Marilyn A. Huestis
      Abstract: Although evidence suggests cannabis impairs driving, its driving‐performance effects are not fully characterized. We aimed to establish cannabis’ effects on driving longitudinal control (with and without alcohol, drivers’ most common drug combination) relative to psychoactive ∆9‐tetrahydrocannabinol (THC) blood concentrations. Current occasional (≥1×/last 3 months, ≤3 days per week) cannabis smokers drank placebo or low‐dose alcohol, and inhaled 500 mg placebo, low (2.9%), or high (6.7%) THC vaporized cannabis over 10 min ad libitum in separate sessions (within‐subject, six conditions). Participants drove (National Advanced Driving Simulator, University of Iowa) simulated drives 0.5–1.3 h post‐inhalation. Blood and breath alcohol samples were collected before (0.17 and 0.42 h) and after (1.4 and 2.3 h) driving. We evaluated the mean speed (relative to limit), standard deviation (SD) of speed, percent time spent >10% above/below the speed limit (percent speed high/percent speed low), longitudinal acceleration, and ability to maintain headway relative to a lead vehicle (headway maintenance) against blood THC and breath alcohol concentrations (BrAC). In N=18 completing drivers, THC was associated with a decreased mean speed, increased percent speed low and increased mean following distance during headway maintenance. BrAC was associated with increased SD speed and increased percent speed high, whereas THC was not. Neither was associated with altered longitudinal acceleration. A less‐than‐additive THC*BrAC interaction was detected in percent speed high (considering only non‐zero data and excluding an outlying drive event), suggesting cannabis mitigated drivers’ tendency to drive faster with alcohol. Cannabis was associated with slower driving and greater headway, suggesting a possible awareness of impairment and attempt to compensate. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-18T05:36:32.39318-05:0
      DOI: 10.1002/jat.3295
       
  • Biotransformation of three phosphate flame retardants and plasticizers in
           primary human hepatocytes: untargeted metabolite screening and
           quantitative assessment
    • Authors: Nele Van den Eede; Ingrid Meester, Walid Maho, Hugo Neels, Adrian Covaci
      Abstract: Tris(2‐butoxyethyl) phosphate (TBOEP), triphenyl phosphate (TPHP) and tris(1‐chloro‐2‐propyl) phosphate (TCIPP) are current high‐volume organophosphate flame retardants/plasticizers (PFRs) and are abundant in the indoor environment. While recent in vitro research has indicated potential toxic effects in the endocrine system, biotransformation of these compounds is still underexplored. In this study, we aimed to characterize the metabolite formation for three PFRs in primary human hepatocytes, an in vitro system that mimics in vivo liver metabolism more closely than hepatic subcellular fractions or cell lines. Cryopreserved human hepatocytes were thawed and suspended in media with 50 μm TBOEP or TCIPP, or 20 μm TPHP up to 2 h. Extracts were analyzed by liquid chromatography–quadrupole‐time‐of‐flight‐mass spectrometry. Quantification of biotransformation products in hepatocytes exposed for 2 h revealed that bis(1‐chloro‐2‐propyl) phosphate and diphenyl phosphate corresponded to less than half of the depletion of TCIPP and TPHP, respectively, while bis(2‐butoxyethyl) 2‐hydroxyethyl phosphate compared to 40–66% of the depletion of TBOEP. Other metabolite structures of these PFRs were produced at 4‐ to 10‐fold lower rates. These findings help interpret biological levels of the major metabolites and relate it to levels of their parent PFR. Percentage of substrate depletion was largest for TBOEP followed by comparable values for TPHP and TCIPP, indicating that hepatic clearance of TPHP and TCIPP would be slower than that of TBOEP. The resulting higher levels and longer presence of TPHP in the circulation after exposure, would allow TPHP a larger time window to exert its suspected adverse effects compared to TBOEP. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-18T01:21:24.069703-05:
      DOI: 10.1002/jat.3293
       
  • Copper toxicology, oxidative stress and inflammation using zebrafish as
           experimental model
    • Abstract: Copper is an essential micronutrient and a key catalytic cofactor in a wide range of enzymes. As a trace element, copper levels are tightly regulated and both its deficit and excess are deleterious to the organism. Under inflammatory conditions, serum copper levels are increased and trigger oxidative stress responses that activate inflammatory responses. Interestingly, copper dyshomeostasis, oxidative stress and inflammation are commonly present in several chronic diseases. Copper exposure can be easily modeled in zebrafish; a consolidated model in toxicology with increasing interest in immunity‐related research. As a result of developmental, economical and genetic advantages, this freshwater teleost is uniquely suitable for chemical and genetic large‐scale screenings, representing a powerful experimental tool for a whole‐organism approach, mechanistic studies, disease modeling and beyond. Copper toxicological and more recently pro‐inflammatory effects have been investigated in both larval and adult zebrafish with breakthrough findings. Here, we provide an overview of copper metabolism in health and disease and its effects on oxidative stress and inflammation responses in zebrafish models. Copper‐induced inflammation is highlighted owing to its potential to easily mimic pro‐oxidative and pro‐inflammatory features that combined with zebrafish genetic tractability could help further in the understanding of copper metabolism, inflammatory responses and related diseases. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-17T06:06:14.614597-05:
      DOI: 10.1002/jat.3303
       
  • n‐butylparaben induces male reproductive disorders via regulation of
           estradiol and estrogen receptors
    • Authors: Linyuan Zhang; Sijin Ding, Peihuan Qiao, Li Dong, Miao Yu, Chong Wang, Ming Zhang, Lixia Zhang, Yimin Li, Ning Tang, Bing Chang
      Abstract: It is well known that inappropriate exposure to exogenous hormones during fetal or neonatal life, such as testosterone (T) and estradiol (E2), leads to adverse reproductive outcomes. In our previous study, the reproductive dysfunction of male rats was characterized by an E2 increase and T decrease after in utero and lactation exposures to n‐butylparaben (n‐BP). In this study, we investigated the synthesis and metabolism pathways of steroid hormones, hormone receptors and the epigenetic modification of male offspring on postnatal day (PND) 21 and PND90 to explore the possible mechanisms of endocrine and reproductive disorders. The expression of steroidogenic acute regulatory protein (StAR), cytochrome cholesterol side‐chain cleavage enzyme (P450scc), estrogen sulfotransferase (SULT1E1) and androgen receptor (AR) in the testes was significantly decreased at the transcript and protein levels; in addition, aromatase (CYP19) and estrogen receptor α (ERα) expression was significantly increased and the methylation rate of the ERα promoter was significantly decreased. These results suggest that increased CYP19 expression and decreased SULT1E1 expression are responsible for the E2 increase. This effect promotes the expression of ERα, which plays a pivotal role in regulating reproductive and endocrine disorders of male rats exposed to n‐BP. Furthermore, the epigenetic hypomethylation of ERα is involved in this regulation processes. Our study is the first to report on the possible mechanism of male rat reproductive disorders induced by the xenoestrogenic chemical n‐BP. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-17T00:36:51.036764-05:
      DOI: 10.1002/jat.3291
       
  • Quantitative evaluation of local pulmonary distribution of TiO2 in rats
           following single or multiple intratracheal administrations of TiO2
           nanoparticles using X‐ray fluorescence microscopy
    • Authors: Guihua Zhang; Naohide Shinohara, Hirokazu Kano, Hideki Senoh, Masaaki Suzuki, Takeshi Sasaki, Shoji Fukushima, Masashi Gamo
      Abstract: Uneven pulmonary nanoparticle (NP) distribution has been described when using single‐dose intratracheal administration tests. Multiple‐dose intratracheal administrations with small quantities of NPs are expected to improve the unevenness of each dose. The differences in local pulmonary NP distribution (called microdistribution) between single‐ and multiple‐dose administrations may cause differential pulmonary responses; however, this has not been evaluated. Here, we quantitatively evaluated the pulmonary microdistribution (per mesh: 100 μm × 100 μm) of TiO2 in lung sections from rats following one, two, three, or four doses of TiO2 NPs at a same total dosage of 10 mg kg−1 using X‐ray fluorescence microscopy. The results indicate that: (i) multiple‐dose administrations show lower variations in TiO2 content (ng mesh−1) for sections of each lobe; (ii) TiO2 appears to be deposited more in the right caudal and accessory lobes located downstream of the administration direction of NP suspensions, and less so in the right middle lobes, irrespective of the number of doses; (iii) there are not prominent differences in the pattern of pulmonary TiO2 microdistribution between rats following single and multiple doses of TiO2 NPs. Additionally, the estimation of pulmonary TiO2 deposition for multiple‐dose administrations imply that every dose of TiO2 would be randomly deposited only in part of the fixed 30–50% of lung areas. The evidence suggests that multiple‐dose administrations do not offer remarkable advantages over single‐dose administration on the pulmonary NP microdistribution, although multiple‐dose administrations may reduce variations in the TiO2 content for each lung lobe. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-16T06:44:51.139091-05:
      DOI: 10.1002/jat.3287
       
  • Gene expression analyses of vitellogenin, choriogenin and estrogen
           receptor subtypes in the livers of male medaka (Oryzias latipes) exposed
           to equine estrogens
    • Authors: Hiroshi Ishibashi; Masaya Uchida, Akiko Koyanagi, Yoshihiro Kagami, Teruhiko Kusano, Ayami Nakao, Ryoko Yamamoto, Nobuhiro Ichikawa, Nobuaki Tominaga, Yasuhiro Ishibashi, Koji Arizono
      Abstract: In the present study, we investigated transcriptional profiles of estrogen‐responsive genes, such as vitellogenins (Vtg1 and Vtg2), choriogenins (ChgL and ChgH) and estrogen receptor subtypes (ERα, ERβ1, and ERβ2), in the liver of male medaka fish (Oryzias latipes) that were exposed to six equine estrogens (1–300 ng l−1) for 3 days. Our quantitative reverse transcription‐polymerase chain reaction (RT‐PCR) analyses revealed that the expression levels of hepatic Vtg, Chg and ERα genes in male medaka responded to various types and concentrations of equine estrogens. The estrogenic potentials of the tested chemicals were in the order of equilin > 17β‐estradiol > equilenin > 17β‐dihydroequilin > 17β‐dihydroequilenin > 17α‐dihydroequilin > 17α‐dihydroequilenin, showing the higher estrogenic potential of equilin than that of 17β‐estradiol. Our results also showed that the estrogenicities of 17β‐dihydroequilin and 17β‐dihydroequilenin were more potent than that of 17α‐dihydroequilin and 17α‐dihydroequilenin. Furthermore, in gene expression analyses of hepatic ER subtypes, observations were made to note that 17β‐estradiol and equilin induced ERα transcription in male medaka, and the ERα transcription level had significantly positive correlations with the expression of Vtg and Chg genes. In contrast, in the same 17β‐estradiol and equilin treatment groups, it was shown that the transcription levels of hepatic ERβ1 and/or ERβ2 had significantly negative correlations with the expression of Vtg and Chg genes. These results suggested some potential involvement of the ER subtypes in the regulation of Vtg and Chg gene expressions in the liver. This is the first report describing the comprehensive analyses of in vivo estrogenicity of the equine estrogens in male medaka. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-11T00:44:02.393114-05:
      DOI: 10.1002/jat.3292
       
  • Combined toxicity of heavy metal mixtures in liver cells
    • Authors: Xialu Lin; Yuanliang Gu, Qi Zhou, Guochuan Mao, Baobo Zou, Jinshun Zhao
      Abstract: With rapid industrialization, China is now facing great challenges in heavy metal contamination in the environment. Human exposure to heavy metals through air, water and food commonly involves a mixture consisting of multiple heavy metals. In this study, eight common heavy metals (Pb, Cd, Hg, Cu, Zn, Mn, Cr, Ni) that cause environmental contamination were selected to investigate the combined toxicity of different heavy metal mixtures in HL7702 cells. Toxicity (24 h LC50) of each individual metal on the cells ranked Hg > Cr = Cd > Cu > Zn > Ni > Mn > Pb; toxicity of the different mixtures ranked: M5 > M3PbHgCd > M5+Mn > M5+Cu > M2CdNi > M4A > M8‐Mn > M8 > M5+Zn > M4B > M8‐Cr > M8‐Zn > M8‐Cu > M8‐Pb > M8‐Cd > M8‐Hg > M8‐Ni > M3PbHgNi > M3CuZnMn. The cytotoxicity data of individual metals were successfully used to build the additive models of two‐ to eight‐component metal mixtures. The comparison between additive model and combination model or partly additive model was useful to evaluate the combined effects in mixture. Synergistic, antagonistic or additive effects of the toxicity were observed in different mixtures. These results suggest that the combined effects should be considered in the risk assessment of heavy metal co‐exposure, and more comprehensive investigations on the combined effects of different heavy metal mixtures are needed in the future. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-10T05:04:15.914494-05:
      DOI: 10.1002/jat.3283
       
  • Diurnal activity patterns as a sensitive behavioural outcome in fish:
           effect of short‐term exposure to treated sewage and a
           sub‐lethal PPCP mixture
    • Authors: Steven D. Melvin; David R. Buck, Larelle D. Fabbro
      Abstract: Sub‐lethal toxicological responses are common occurrences in aquatic animals exposed to sewage wastewater and organic wastewater contaminants. Behavioural alterations are particularly sensitive indicators of sub‐lethal toxicological stress in animals exposed to various pollutants, and often correlate with higher‐level outcomes. Diurnal activity patterns in many fish species are sensitive to changes in natural biotic factors, but few studies have explored how environmental pollutants influence such rhythms. We investigated diurnal activity patterns in the mosquitofish (Gambusia holbrooki), after exposure to UV‐treated sewage and a mixture of key contaminants identified through chemical analysis and subsequent risk‐based prioritization of the wastewater. Exposure to 50% and 100% wastewater abolished daytime activity levels in male, but not female fish. Chemical analysis identified fluoxetine, diazinon and triclosan above their reported predicted‐no‐effect‐concentrations (PNECs), and fish were thus exposed to a mixture of these compounds at 1, 10 and 100 μg l–1. Behavioural responses were highly consistent between fish exposed to wastewater and the contaminant mixture, indicating that these prioritized contaminants are indeed likely contributing to the observed effects. Effective concentrations of the mixture were considerably lower than those reported as eliciting behavioural effects in previous studies exploring each of these compounds alone. Results warn of the potential for negative higher‐level consequences associated with exposures of fish to common organic wastewater contaminants, as altered diurnal activity patterns could conceivably scale‐up to influence performance including foraging success and predator avoidance. Further research is necessary to increase our understanding of linkages between alterations to diurnal activities and effects at the population level. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-09T05:35:36.367389-05:
      DOI: 10.1002/jat.3284
       
  • Integrated decision strategies for skin sensitization hazard
    • Authors: Judy Strickland; Qingda Zang, Nicole Kleinstreuer, Michael Paris, David M. Lehmann, Neepa Choksi, Joanna Matheson, Abigail Jacobs, Anna Lowit, David Allen, Warren Casey
      Abstract: One of the top priorities of the Interagency Coordinating Committee for the Validation of Alternative Methods (ICCVAM) is the identification and evaluation of non‐animal alternatives for skin sensitization testing. Although skin sensitization is a complex process, the key biological events of the process have been well characterized in an adverse outcome pathway (AOP) proposed by the Organisation for Economic Co‐operation and Development (OECD). Accordingly, ICCVAM is working to develop integrated decision strategies based on the AOP using in vitro, in chemico and in silico information. Data were compiled for 120 substances tested in the murine local lymph node assay (LLNA), direct peptide reactivity assay (DPRA), human cell line activation test (h‐CLAT) and KeratinoSens assay. Data for six physicochemical properties, which may affect skin penetration, were also collected, and skin sensitization read‐across predictions were performed using OECD QSAR Toolbox. All data were combined into a variety of potential integrated decision strategies to predict LLNA outcomes using a training set of 94 substances and an external test set of 26 substances. Fifty‐four models were built using multiple combinations of machine learning approaches and predictor variables. The seven models with the highest accuracy (89–96% for the test set and 96–99% for the training set) for predicting LLNA outcomes used a support vector machine (SVM) approach with different combinations of predictor variables. The performance statistics of the SVM models were higher than any of the non‐animal tests alone and higher than simple test battery approaches using these methods. These data suggest that computational approaches are promising tools to effectively integrate data sources to identify potential skin sensitizers without animal testing. Published 2016. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
      PubDate: 2016-02-06T02:17:09.301506-05:
      DOI: 10.1002/jat.3281
       
  • Gelucire and Gelucire‐PEG400 formulations; tolerability in species
           used for non‐clinical safety testing after oral (gavage) dosing
    • Authors: Mikael Elander; Jette B. Boll, Anne S. Hojman, Allan D. Rasmussen
      Abstract: The selection of a vehicle for oral formulations of compounds to be used in non‐clinical safety studies is a challenge for poorly soluble compounds. Typically a compromise between solubility and tolerability has to be reached. Vehicle tolerability data are not readily available for a number of vehicles, and a series of oral tolerability studies were, therefore, conducted with Gelucire and Gelucire:PEG400 formulations in rats, dogs and minipigs in order to determine tolerable daily dose volumes in these species. Gelucire and Gelucire:PEG400 formulations were assessed in studies for up to 5 days in minipigs, 7 days in rats and up to 39 weeks in dogs. Gastrointestinal side effects in terms of soft and/or liquid faeces were noted in all species, but the sensitivity to these effects differed between species with the dog being the most sensitive. It was concluded that Gelucire:PEG400 (90:10) was tolerated in Beagle dogs when administered at 1 ml kg–1 once daily for 39 weeks, and 100% Gelucire was tolerated in the rat and the minipig when administered once daily at 5 ml kg–1 for 5 days. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-05T06:03:37.866444-05:
      DOI: 10.1002/jat.3296
       
  • Nanosuspension formulations of poorly water‐soluble compounds for
           intravenous administration in exploratory toxicity studies: in vitro and
           in vivo evaluation
    • Authors: Hisako Fujimura; Takao Komasaka, Taizo Tomari, Yasunori Kitano, Kouji Takekawa
      Abstract: This study was conducted to investigate the use of a nanosuspension for intravenous injection into dogs to increase exposure without toxic additives for preclinical studies in the discovery stage. Nanosuspensions were prepared with a mixer mill and zirconia beads with a vehicle of 2% (w/v) poloxamer 338, which was confirmed to lead to no histamine release in dogs. Sterilized nanosuspensions of poorly water‐soluble compounds, cilostazol (Cil), spironolactone (Spi) and probucol (Pro), at 10 mg ml−1 were obtained by milling for 30 min, followed by autoclaving for 20 min at 121 °C and milling for 30 min (mill–autoclave–mill method). The particle sizes (d50) of Cil, Spi and Pro were 0.554, 0.484 and 0.377 µm, respectively, and the percentages of the nominal concentration were 79.1%, 99.6% and 75.4%, respectively. In chromatographic data, no extra peaks were observed. The particle size of Cil was 0.564 µm after storage for 16 days at 2–8 °C. Cil in nanosuspension, but not in microsuspension, rapidly dissolved in dog plasma. Cil nanosuspension at 0.4 mg kg−1 and Cil saline solution at 0.03 mg kg−1, around the saturation solubility, were intravenously administered to dogs. Nanosuspension increased exposure. The versatility of the mill–autoclave–mill method was checked for 15 compounds, and the particle size of 12 compounds was in the nano range. The nanosuspension optimized in this study may be useful for intravenous toxicological and pharmacological studies in the early stage of drug development. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-05T05:35:05.545267-05:
      DOI: 10.1002/jat.3280
       
  • Depth‐dependent stratum corneum permeability in human skin in vitro
    • Abstract: The stratum corneum (SC), a permeable membrane, limits percutaneous penetration. As SC chemical and structural properties responsible for skin barrier function appear depth‐related, we conducted an in vitro dermatopharmacokinetic study on intact and adhesive tape‐stripped skin samples to clarify whether SC is a homogeneous barrier for chemical transport. SC concentration–thickness profiles were determined for four C‐14 labeled model chemicals, panthenol, benzoic acid, paraoxon and butenafine, using the tape‐stripping approach. Data analysis with the unsteady‐state diffusion equation of Fick's second law permitted a chemical diffusion coefficient in SC. To evaluate the consistency of SC permeability from its surface to lower levels, the skin was tape‐stripped five to 10 times to remove the upper cell layers before chemical application, such that diffusion coefficients could be determined from three SC depth levels (0, 5 and 10 tape strips). Results suggested the depth‐dependency of SC permeability to panthenol, benzoic acid and butenafine; the diffusion coefficient of panthenol decreased significantly after the first five tape strips and subsequently remained consistent. A progressive increase in diffusion coefficients of benzoic acid and butenafine was observed as tape‐stripping levels increased. The removal of superficial SC did not result in a significant difference in the paraoxon diffusion coefficient. For individual chemicals, a variation in the diffusion coefficient from SC surface to deeper layers agreed with the change of the diffusion coefficient over time in intact skin. Characterization of the SC properties contributing to the depth‐dependent SC permeability will hopefully provide further insight to skin penetration/decontamination. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-03T21:43:54.622756-05:
      DOI: 10.1002/jat.3289
       
  • Evaluation of kidney injury biomarkers in rat amniotic fluid after
           gestational exposure to cadmium
    • Abstract: Cadmium is a well‐characterized nephrotoxic agent that is also capable of accumulating and diffusing across the placenta; however, only a few studies have addressed its effects over fetal kidneys and none of them has used a panel of sensitive and specific biomarkers for the detection of kidney injury. The goal of this study was to determine cadmium renal effects in rat fetuses by the quantification of early kidney injury biomarkers. Pregnant Wistar rats were exposed by inhalation to an isotonic saline solution or to CdCl2 solution (DDel=1.48 mg Cd kg−1 day−1) during gestational days (GD) 8–20. On GD 21, dams were euthanized and samples obtained. Kidney injury biomarkers were quantified in amniotic fluid samples and fetal kidneys were microscopically evaluated to search for histological alterations. Our results showed that cadmium exposure significantly raised albumin, osteopontin, vascular endothelial growth factor and tissue inhibitor of metalloproteinases‐1 levels in amniotic fluid, whereas it decreased creatinine. Clusterin, calbindin and IFN‐inducible protein 10 did not show any change. Accordingly, histological findings showed tubular damage and precipitations in the renal pelvis. In conclusion, gestational exposure to cadmium induces structural alterations in fetal renal tissue that can be detected by some kidney injury biomarkers in amniotic fluid samples. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-01-27T01:09:57.621027-05:
      DOI: 10.1002/jat.3286
       
  • Systems toxicology of chemically induced liver and kidney injuries:
           histopathology‐associated gene co‐expression modules
    • Authors: Jerez A. Te; Mohamed Diwan M. AbdulHameed, Anders Wallqvist
      Abstract: Organ injuries caused by environmental chemical exposures or use of pharmaceutical drugs pose a serious health risk that may be difficult to assess because of a lack of non‐invasive diagnostic tests. Mapping chemical injuries to organ‐specific histopathology outcomes via biomarkers will provide a foundation for designing precise and robust diagnostic tests. We identified co‐expressed genes (modules) specific to injury endpoints using the Open Toxicogenomics Project‐Genomics Assisted Toxicity Evaluation System (TG‐GATEs) – a toxicogenomics database containing organ‐specific gene expression data matched to dose‐ and time‐dependent chemical exposures and adverse histopathology assessments in Sprague–Dawley rats. We proposed a protocol for selecting gene modules associated with chemical‐induced injuries that classify 11 liver and eight kidney histopathology endpoints based on dose‐dependent activation of the identified modules. We showed that the activation of the modules for a particular chemical exposure condition, i.e., chemical‐time‐dose combination, correlated with the severity of histopathological damage in a dose‐dependent manner. Furthermore, the modules could distinguish different types of injuries caused by chemical exposures as well as determine whether the injury module activation was specific to the tissue of origin (liver and kidney). The generated modules provide a link between toxic chemical exposures, different molecular initiating events among underlying molecular pathways and resultant organ damage. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Journal of Applied Toxicology published by John Wiley & Sons, Ltd.
      PubDate: 2016-01-04T02:22:07.710446-05:
      DOI: 10.1002/jat.3278
       
  • Changes in RANKL and osteoprotegerin expression after chronic exposure to
           indoor air pollution as a result of cooking with biomass fuel
    • Authors: Hirak Saha; Bidisha Mukherjee, Banani Bindhani, Manas Ranjan Ray
      Abstract: The impact of indoor air pollution as a result of cooking with unprocessed biomass on membrane‐bound and serum receptor activator of nuclear factor‐kappa ligand 1 (RANKL), its soluble decoy receptor osteoprotegerin (OPG) and osteoclast precursor CD14+CD16+ monocytes was investigated. Seventy‐four pre‐menopausal women from eastern India using biomass and 65 control women who cooked with cleaner liquefied petroleum gas were enrolled. PM10 and PM2.5 levels in their indoor air were measured with real‐time aerosol monitors. The levels of membrane‐bound RANKL on leukocytes and percentage CD14+CD16+ monocytes in the subjects' blood were assayed by flow cytometry. Soluble RANKL and OPG in serum were measured by ELISA. The results showed that PM10 and PM2.5 levels were significantly higher in the indoor air of biomass‐using households. Compared with the control women, the levels of CD4+ and CD19+ lymphocytes and circulating granulocytes with elevated levels of membrane‐bound RANKL were higher in biomass users. The serum levels of RANKL were increased by 41% whereas serum OPG was reduced by 22% among biomass users. The absolute number of CD14+CD16+ monocytes was significantly increased in biomass users than the control women. After controlling for potential confounders, PM10 and PM2.5 levels were found to be positively associated with leukocyte and serum RANKL and CD14+CD16+ monocyte levels, but negatively with serum OPG. From these results, we can conclude that chronic exposure to biomass smoke increased membrane‐bound and soluble RANKL and circulating osteoclast precursors but decreased OPG, suggesting an increased risk of bone resorption and consequent osteoporosis in biomass‐exposed women of a child‐bearing age. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-22T02:34:56.926053-05:
      DOI: 10.1002/jat.3275
       
  • Discrimination of skin sensitizers from non‐sensitizers by
           interleukin‐1α and interleukin‐6 production on cultured
           human keratinocytes
    • Abstract: In vitro testing methods for classifying sensitizers could be valuable alternatives to in vivo sensitization testing using animal models, such as the murine local lymph node assay (LLNA) and the guinea pig maximization test (GMT), but there remains a need for in vitro methods that are more accurate and simpler to distinguish skin sensitizers from non‐sensitizers. Thus, the aim of our study was to establish an in vitro assay as a screening tool for detecting skin sensitizers using the human keratinocyte cell line, HaCaT. HaCaT cells were exposed to 16 relevant skin sensitizers and 6 skin non‐sensitizers. The highest dose used was the dose causing 75% cell viability (CV75) that we determined by an MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] assay. The levels of extracellular production of interleukin‐1α (IL‐1α) and IL‐6 were measured. The sensitivity of IL‐1α was 63%, specificity was 83% and accuracy was 68%. In the case of IL‐6, sensitivity: 69%, specificity: 83% and accuracy: 73%. Thus, this study suggests that measuring extracellular production of pro‐inflammatory cytokines IL‐1α and IL‐6 by human HaCaT cells may potentially classify skin sensitizers from non‐sensitizers. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-22T02:23:21.954762-05:
      DOI: 10.1002/jat.3274
       
  • Long‐term exposure to high levels of decabrominated diphenyl ether
           inhibits CD4 T‐cell functions in C57Bl/6 mice
    • Authors: Yan Feng; Weihong Zeng, Ying Wang, Hao Shen, Yan Wang
      Abstract: In recent years, the adverse health effects of decabrominated diphenyl ether (BDE‐209) have raised more concerns as a growing number of studies reported its persistence in the environment and abundance in the human population, especially in occupational environmental compartments and exposed personnel. This study applies our previous animal model simulating occupational exposure to BDE‐209 to investigate its potential adverse effects on CD4 T cells. Female C57Bl/6 mice were orally gavaged with BDE‐209 at a dose of 800 mg kg−1 every 2 days for 10 months and the blood of each mouse was collected for analysis. Kinetic changes of the peripheral immune system were investigated from 1 to 5 months of exposure. The chronic effects on cytokine production, proliferation and the antigen‐specific responses of CD4 T cells were evaluated at 7, 9 and 10 months, respectively. The results have shown that impaired proliferation and cytokine (IFN‐γ, IL‐2 or TNF‐α) production of CD4 T cells were observed in BDE‐209‐exposed mice, accompanied by increased T regulatory cells in the blood. BDE‐209 exposure in vitro also suppressed the reactivity of CD4 T cells at concentrations of 0.01, 0.1, 1 and 10 μM. Furthermore, we observed weaker antigen‐specific CD4 T‐cell responses to Listeria monocytogenes infection in the mice exposed to BDE‐209, suggesting decreased resistance to exogenous pathogens. Taken together, these observations indicate an impaired cellular immunity after long‐term and relative high‐dose exposure to BDE‐209 in adult mice. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-18T06:37:03.854296-05:
      DOI: 10.1002/jat.3270
       
  • BMDExpress Data Viewer ‐ a visualization tool to analyze BMDExpress
           datasets
    • Authors: Byron Kuo; A. Francina Webster, Russell S. Thomas, Carole L. Yauk
      Abstract: Regulatory agencies increasingly apply benchmark dose (BMD) modeling to determine points of departure for risk assessment. BMDExpress applies BMD modeling to transcriptomic datasets to identify transcriptional BMDs. However, graphing and analytical capabilities within BMDExpress are limited, and the analysis of output files is challenging. We developed a web‐based application, BMDExpress Data Viewer (http://apps.sciome.com:8082/BMDX_Viewer/), for visualizing and graphing BMDExpress output files. The application consists of “Summary Visualization” and “Dataset Exploratory” tools. Through analysis of transcriptomic datasets of the toxicants furan and 4,4′‐methylenebis(N,N‐dimethyl)benzenamine, we demonstrate that the “Summary Visualization Tools” can be used to examine distributions of gene and pathway BMD values, and to derive a potential point of departure value based on summary statistics. By applying filters on enrichment P‐values and minimum number of significant genes, the “Functional Enrichment Analysis” tool enables the user to select biological processes or pathways that are selectively perturbed by chemical exposure and identify the related BMD. The “Multiple Dataset Comparison” tool enables comparison of gene and pathway BMD values across multiple experiments (e.g., across timepoints or tissues). The “BMDL‐BMD Range Plotter” tool facilitates the observation of BMD trends across biological processes or pathways. Through our case studies, we demonstrate that BMDExpress Data Viewer is a useful tool to visualize, explore and analyze BMDExpress output files. Visualizing the data in this manner enables rapid assessment of data quality, model fit, doses of peak activity, most sensitive pathway perturbations and other metrics that will be useful in applying toxicogenomics in risk assessment. © 2015 Her Majesty the Queen in Right of Canada. Journal of Applied Toxicology published by John Wiley & Sons, Ltd.
      PubDate: 2015-12-15T13:42:17.063581-05:
      DOI: 10.1002/jat.3265
       
  • Sulfation of benzyl alcohol by the human cytosolic sulfotransferases
           (SULTs): a systematic analysis
    • Abstract: The aim of the present study was to identify human cytosolic sulfotransferases (SULTs) that are capable of sulfating benzyl alcohol and to examine whether benzyl alcohol sulfation may occur in cultured human cells as well as in human organ homogenates. A systematic analysis revealed that of the 13 known human SULTs, SULT1A1 SULT1A2, SULTA3, and SULT1B1 are capable of mediating the sulfation of benzyl alcohol. The kinetic parameters of SULT1A1 that showed the strongest benzyl alcohol‐sulfating activity were determined. HepG2 human hepatoma cells were used to demonstrate the generation and release of sulfated benzyl alcohol under the metabolic settings. Moreover, the cytosol or S9 fractions of human liver, lung, kidney and small intestine were examined to verify the presence of benzyl alcohol sulfating activity in vivo. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-11T08:59:51.245844-05:
      DOI: 10.1002/jat.3268
       
  • Dibutyltin‐induced alterations of interleukin 1beta secretion from
           human immune cells
    • Abstract: Dibutyltin (DBT) is used to stabilize polyvinyl chloride plastics (including pipes that distribute drinking water) and as a de‐worming agent in poultry. DBT is found in human blood, and DBT exposures alter the secretion of tumor necrosis factor alpha and interferon gamma from lymphocytes. Interleukin (IL)‐1β is a proinflammatory cytokine that regulates cellular growth, tissue restoration and immune response regulation. IL‐1β plays a role in increasing invasiveness of certain tumors. This study reveals that exposures to DBT (24 h, 48 h and 6 days) modify the secretion of IL‐1β from increasingly reconstituted preparations of human immune cells (highly enriched human natural killer cells, monocyte‐depleted [MD] peripheral blood mononuclear cells [PBMCs], PBMCs, granulocytes and a preparation combining both PBMCs and granulocytes). DBT altered IL‐1β secretion from all cell preparations. Higher concentrations of DBT (5 and 2.5 μm) decreased the secretion of IL‐1β, while lower concentrations of DBT (0.1 and 0.05 μm) increased the secretion of IL‐1β. Selected signaling pathways were examined in MD‐PBMCs to determine if they play a role in DBT‐induced elevations of IL‐1β secretion. Pathways examined were IL‐1β converting enzyme (caspase 1), mitogen‐activated protein kinases and nuclear factor kappa B. Caspase 1 and mitogen‐activated protein kinase pathways appear to be utilized by DBT in increasing IL‐1β secretion. These results indicate that DBT alters IL‐1β secretion from human immune cells in an ex. vivo system utilizing several IL‐1β regulating signaling pathways. Thus, DBT may have the potential to alter IL‐1β secretion in an in vivo system. Copyright © 2016 John Wiley & Sons, Ltd.
       
  • Acetyl L‐carnitine targets adenosine triphosphate synthase in
           protecting zebrafish embryos from toxicities induced by verapamil and
           ketamine: An in vivo assessment
    • Abstract: Verapamil is a Ca2+ channel blocker and is highly prescribed as an anti‐anginal, antiarrhythmic and antihypertensive drug. Ketamine, an antagonist of the Ca2+‐permeable N‐methyl‐d‐aspartate‐type glutamate receptors, is a pediatric anesthetic. Previously we have shown that acetyl l‐carnitine (ALCAR) reverses ketamine‐induced attenuation of heart rate and neurotoxicity in zebrafish embryos. Here, we used 48 h post‐fertilization zebrafish embryos that were exposed to relevant drugs for 2 or 4 h. Heart beat and overall development were monitored in vivo. In 48 h post‐fertilization embryos, 2 mm ketamine reduced heart rate in a 2 or 4 h exposure and 0.5 mm ALCAR neutralized this effect. ALCAR could reverse ketamine's effect, possibly through a compensatory mechanism involving extracellular Ca2+ entry through L‐type Ca2+ channels that ALCAR is known to activate. Hence, we used verapamil to block the L‐type Ca2+ channels. Verapamil was more potent in attenuating heart rate and inducing morphological defects in the embryos compared to ketamine at specific times of exposure. ALCAR reversed cardiotoxicity and developmental toxicity in the embryos exposed to verapamil or verapamil plus ketamine, even in the presence of 3,4,5‐trimethoxybenzoic acid 8‐(diethylamino)octyl ester, an inhibitor of intracellular Ca2+ release suggesting that ALCAR acts via effectors downstream of Ca2+. In fact, ALCAR's protective effect was blunted by oligomycin A, an inhibitor of adenosine triphosphate synthase that acts downstream of Ca2+ during adenosine triphosphate generation. We have identified, for the first time, using in vivo studies, a downstream effector of ALCAR that is critical in abrogating ketamine‐ and verapamil‐induced developmental toxicities. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
       
  • Investigation on the mechanism of non‐photocatalytically
           TiO2‐induced reactive oxygen species and its significance on cell
           cycle and morphology
    • Abstract: Titanium dioxide (TiO2) nanoparticles are widely used in daily human life, and were reported to elicit biological effects such as oxidative stress either generating reactive oxygen species (ROS) or causing cell necrosis without generating ROS, whose underlying molecular mechanisms are not yet known. In this study, the role of dissolved oxygen in TiO2 catalytic activity in dark environment, and long‐term cytotoxic effects of TiO2 exposure were investigated. To determine the effect of dissolved oxygen, the anatase‐TiO2 nanoparticle suspension was prepared both in deoxygenated and regular MilliQ water, and a ~ 9‐fold higher ROS in regular MilliQ samples was observed compared to deoxygenated samples while in the dark, which suggested dissolved oxygen as the driving agent behind the TiO2 catalytic reaction. On the other hand, the differential cell viability and endogenous ROS activity was demonstrated through a sensitive macrophage‐based assay, on a dose‐ and time‐dependent manner. Both the cell number and endogenous ROS activity increased with increase in time till 48 h, followed by a reduction at 72 h exposure period. Long‐term exposures to these nanoparticles even at low concentrations were found detrimental to cells, where late apoptosis until 48 h and necrosis at 72 h leading to cell death were noted. Late apoptotic events and cell membrane cytoskeletal actin rearrangement observed were hypothesized to be induced by particle‐mediated cellular ROS. This in addition to radical generation ability of TiO2 in the dark will help further in better understanding of the toxicity mechanism in cells beyond ROS generation. Copyright © 2016 John Wiley & Sons, Ltd.
       
  • Non‐clinical safety assessment of single and repeated administration
           of gE/AS01 zoster vaccine in rabbits
    • Abstract: HZ/su is an investigational recombinant subunit vaccine for the prevention of shingles, a disease resulting from the reactivation of varicella zoster virus. The vaccine is composed of recombinant varicella zoster virus glycoprotein E (gE), and liposome‐based Adjuvant System AS01. To evaluate the potential local and systemic effects of this vaccine, three studies were performed in rabbits. In the first two studies, rabbits received a single intramuscular (IM; study 1) or subcutaneous (SC; study 2) dose of gE/AS01, AS01 alone (in study 2 only) or saline, and the local tolerance was evaluated up to 3 days after administration. Under these conditions, only local inflammatory reactions at the injection sites were detected by microscopic evaluation. In the third study, gE/AS01, AS01 alone or saline, were injected SC or IM on four occasions at 2 week intervals. General health status, local tolerance, ophthalmology, haematology and blood chemistry parameters were monitored. Macroscopic and microscopic evaluations were performed after termination of the study. The only treatment‐related changes included a transient increase in neutrophils, C‐reactive protein and fibrinogen levels and microscopic signs of inflammation at the injection sites, which are expected observations related to the elicited inflammatory reaction. The SC and IM routes of administration produced similar systemic effects. However, microscopic findings at the injection sites differed. One month after the last injection, recovery was complete in all groups. In conclusion, the single and repeated SC and IM administration of the gE/AS01 vaccine were locally and systemically well‐tolerated in rabbits and support the clinical development of the vaccine. Copyright © 2016 John Wiley & Sons, Ltd.
       
  • Development of novel in vitro photosafety assays focused on the
           Keap1–Nrf2–ARE pathway
    • Abstract: Although photoallergens require UV energy for antigen formation, the subsequent immune response is considered to be the same as in ordinary skin sensitization. Therefore, in vitro tests for skin sensitization should also be applicable for photoallergy testing. In this study, we examined whether activation of the Keap1 (Kelch‐like ECH‐associated protein 1)–Nrf2 (nuclear factor‐erythroid 2‐related factor 2)–ARE (antioxidant response element) pathway could be used to assess the photoallergenic potential of chemicals, using the reporter cell line AREc32 or KeratinoSensTM. First, we identified an appropriate UVA irradiation dose [5 J cm–2 irradiation in phosphate‐buffered saline (PBS)] by investigating the effect of UV irradiation on ARE‐dependent gene induction using untreated or 6‐methylcoumarin (6‐MC)‐treated cells. Irradiation of well‐known photoallergens under this condition increased ARE‐dependent gene expression by more than 50% compared with both vehicle and non‐irradiated controls. When the cut‐off value for detecting photoallergens was set at 50% induction, the accuracy of predicting photoallergenic/phototoxic chemicals was 70% in AREc32 cells and 67% in KeratinoSensTM cells, and the specificity was 100% in each case. We designate these assays as a photo‐ARE assay and photo‐KeratinoSensTM, respectively. Our results suggest that activation of the Keap1‐Nrf2‐ARE pathway is an effective biomarker for evaluating both photoallergenic and phototoxic potentials. Either of the above tests might be a useful component of a battery of in vitro tests/in silico methods for predicting the photoallergenicity and phototoxicity of chemicals. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • Benzo(a)pyrene inhibits migration and invasion of extravillous trophoblast
           HTR‐8/SVneo cells via activation of the ERK and JNK pathway
    • Abstract: Benzo(a)pyrene (BaP) is a persistent organic pollutant (POP) that is a serious threat to human health. Numerous studies have shown that BaP causes adverse effects in pregnancy, but the mechanism remains unclear. The moderate invasion of trophoblast cells into the endometrium is an important factor during successful embryo implantation. The aim of this study was to investigate the effect and mechanism of BaP on the invasion and migration of trophoblast cells. HTR‐8/SVneo cells were treated with different concentrations (1, 5, 10, 25, 50 and 100 μM) of BaP. The invasion and migration of HTR‐8/SVneo cells were observed after BaP treatment. The protein levels related to migration and invasion was detected by Western blot. The results confirmed that BaP inhibits the migration and invasion of extravillous trophoblast HTR‐8/SVneo cells. Further investigations indicated that the protein levels of MMP‐2, MMP‐9 and E‐cadherin in HTR‐8/SVneo cells were changed by BaP treatment. Moreover, the data demonstrated that BaP activated the MAPK signaling pathway. Pretreatment with specific inhibitors of MAPK rescued BaP‐induced change in the migration and invasion of HTR‐8/SVneo cells. Taken together, our results indicated that BaP inhibits invasion and the migration of HTR‐8/SVneo cells, which might cause a failure in early pregnancy. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • Oxidative stress‐related DNA damage and homologous recombination
           repairing induced by N,N‐dimethylformamide
    • Abstract: The intensified anthropogenic release of N,N‐dimethylformamide (DMF) has been proven to have hepatotoxic effects. However, the potential mechanism for DMF‐induced toxicity has rarely been investigated. Our research implicated that DMF induced a significantly dose‐dependent increase in reactive oxygen species (ROS) in HL‐7702 human liver cells. Moreover, oxidative stress‐related DNA damage, marked as 8‐hydroxy‐2′‐deoxyguanosine, was increased 1.5‐fold at 100 mmol l–1. The most severe DNA lesion (double‐strand break, DSB), measured as the formation of γH2AX foci, was increased at/above 6.4 mmol l–1, and approximately 50% of cells underwent DSB at the peak induction. Subsequently, the DNA repair system triggered by molecules of RAD50 and MRE11A induced the homologous recombination (HR) pathway by upregulation of both gene and protein levels of RAD50, RAD51, XRCC2 and XRCC3 at 16 mmol l–1 and was attenuated at 40 mmol l–1. Consequently, cellular death observed at 40 mmol l–1 was exaggerated compared with exposure at 16 mmol l–1. Although the exact mechanism relying on the DMF‐induced hepatotoxicity needs further clarification, oxidative stress and DNA damage involved in DSBs partially explain the reason for DMF‐induced liver injury. Oxidative stress‐induced DNA damage should be first considered during risk assessment on liver‐targeted chemicals. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • Functional expressions of adenosine triphosphate‐binding cassette
           transporters during the development of zebrafish embryos and their effects
           
    • Abstract: Adenosine triphosphate‐binding cassette (ABC) transporters, including ABCB, ABCC and ABCG families represent general biological defenses against environmental toxicants in varieties of marine and freshwater organisms, but their physiological functions at differential developmental stages of zebrafish embryos remain undefined. In this work, functional expressions of typical ABC transporters including P‐glycoprotein (Pgp), multiresistance associated protein 1 (Mrp1) and Mrp2 were studied in zebrafish embryos at 4, 24, 48 and 72 h post‐fertilization (hpf). As a result, both the gene expressions and activities of Pgp and Mrps increased with the development of embryos. Correspondingly, 4–72 hpf embryos exhibited an increased tolerance to the toxicity caused by cadmium chloride (CdCl2) and β‐naphthoflavone (BNF) with time. Such a correlation was assumed caused by the involvement of ABC transporters in the detoxification of chemicals. In addition, the assumption was supported by the fact that model efflux inhibitors of Pgp and Mrps such as reversine 205 and MK571 significantly inhibited the efflux of toxicants and increased the toxicity of Cd and BNF in zebrafish embryos. Moreover, exposure to CdCl2 and BNF induced the gene expressions of Pgp and Mrp1 in 72 hpf embryos. Thus, functional expressions of Pgp and Mrps increased with the development of zebrafish embryos, which could cause an increasing tolerance of zebrafish embryos to CdCl2 and BNF. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • Tris(2‐chloroethyl)phosphate‐induced cell growth arrest via
           attenuation of SIRT1‐independent PI3K/Akt/mTOR pathway
    • Abstract: Tris(2‐chloroethyl)phosphate (TCEP) as an organophosphorus flame retardant and plasticizer has been widely used in industrial and household products. It not only was detected in residential indoor air and dust, surface and drinking water, but also in human plasma and breast milk, and tissue samples of liver, kidneys and brain from rodents. TCEP is classified as carcinogenic category 2 and toxic for reproduction category 1B. Sufficient evidence from experimental animals indicated carcinogenicity of TCEP in the liver, and kidneys as well as cell loss in the brain. However, the underlying mechanisms of TCEP‐induced hepatotoxicity are mostly unknown. We investigated the in vitro effects of TCEP as well as TCEP‐induced cell growth in the L02 and HepG2 cells through the PI3K/Akt/mTOR pathway. We found that TCEP reduced cell viability of these cell lines, induced the cell growth arrest, upregulated mRNA and protein levels of SIRT1, and attenuated the PI3K/Akt/mTOR pathway. However, growth arrest of the L02 and HepG2 cells were aggravated after inhibiting the SIRT1 expression with EX‐527. The findings above suggested that TCEP induced the cell growth arrest of L02 and HepG2 cells via attenuation of the SIRT1‐independent PI3K/Akt/mTOR pathway. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • The impact of caffeine on connexin expression in the embryonic chick
           cardiomyocyte micromass culture system
    • Abstract: Cardiomyocytes are electrically coupled by gap junctions, defined as clusters of low‐resistance multisubunit transmembrane channels composed of connexins (Cxs). The expression of Cx40, Cx43 and Cx45, which are present in cardiomyocytes, is known to be developmentally regulated. This study investigates the premise that alterations in gap junction proteins are one of the mechanisms by which teratogens may act. Specifically, those molecules known to be teratogenic in humans could cause their effects via disruption of cell‐to‐cell communication pathways, resulting in an inability to co‐ordinate tissue development. Caffeine significantly inhibited contractile activity at concentrations above and including 1500 μm (P < 0.05), while not affecting cell viability and total protein, in the embryonic chick cardiomyocyte micromass culture system. The effects of caffeine on key cardiac gap junction protein (Cx40, Cx43 and Cx45) expression were analysed using immunocytochemistry and in‐cell Western blotting. The results indicated that caffeine altered the expression pattern of Cx40, Cx43 and Cx45 at non‐cytotoxic concentrations (≥2000 μm), i.e., at concentrations that did not affect total cell protein and cell viability. In addition the effects of caffeine on cardiomyocyte formation and function (contractile activity score) were correlated with modulation of Cxs (Cx40, Cx43 and Cx45) expression, at above and including 2000 μm caffeine concentrations (P < 0.05). These experiments provide evidence that embryonic chick cardiomyocyte micromass culture may be a useful in vitro method for mechanistic studies of perturbation of embryonic heart development. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • Automated swimming activity monitor for examining temporal patterns of
           toxicant effects on individual Daphnia magna
    • Abstract: Aquatic pollutants are often biologically active at low concentrations and impact on biota in combination with other abiotic stressors. Traditional toxicity tests may not detect these effects, and there is a need for sensitive high‐throughput methods for detecting sublethal effects. We have evaluated an automated infra‐red (IR) light‐based monitor for recording the swimming activity of Daphnia magna to establish temporal patterns of toxicant effects on an individual level. Activity was recorded for 48 h and the sensitivity of the monitor was evaluated by exposing D. magna to the reference chemicals K2Cr2O7 at 15, 20 and 25 °C and 2,4‐dichlorophenol at 20 °C. Significant effects (P < 0.001) of toxicant concentrations, exposure time and incubation temperatures were observed. At 15 °C, the swimming activity remained unchanged for 48 h at sublethal concentrations of K2Cr2O7 whereas activity at 20 and 25 °C was more biphasic with decreases in activity occurring after 12–18 h. A similar biphasic pattern was observed after 2,4‐dichlorophenol exposure at 20 °C. EC50 values for 2,4‐dichlorophenol and K2Cr2O7 determined from automated recording of swimming activity showed increasing toxicity with time corresponding to decreases in EC50 of 0.03–0.07 mg l–1 h–1. EC50 values determined after 48 h were comparable or lower than EC50 values based on visual inspection according to ISO 6341. The results demonstrated that the swimming activity monitor is capable of detecting sublethal behavioural effects that are toxicant and temperature dependent. The method allows EC values to be established at different time points and can serve as a high‐throughput screening tool in toxicity testing. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • Issue Information ‐ TOC
    • Abstract: No abstract is available for this article.
       
  • Effect and mechanism of waterborne prolonged Zn exposure influencing
           hepatic lipid metabolism in javelin goby Synechogobius hasta
    • Abstract: The present study was conducted to determine the effect and mechanism of waterborne Zn exposure influencing hepatic lipid deposition and metabolism in javelin goby Synechogobius hasta. S. hasta were exposed to four waterborne Zn concentrations (Zn 0.005 [control], 0.18, 0.36 and 0.55 mg l−1, respectively) for 60 days. Sampling occurred at days 20, 40 and 60, respectively. Zn exposure increased Zn content, declined hepatic lipid content and reduced viscerosomatic and hepatosomatic indices and lipogenic enzyme activities, including 6‐phosphogluconate dehydrogenase (6PGD), glucose‐6‐phosphate dehydrogenase (G6PD), malic enzyme (ME) and fatty acid synthase (FAS). At days 20 and 60, Zn exposure decreased hepatic mRNA levels of 6PGD, G6PD, ME, FAS, acetyl‐CoA carboxylase (ACC)α, ACCβ, hormone‐sensitive lipase (HSL)a, HSLb, sterol‐regulator element‐binding protein (SREBP)‐1, peroxisome proliferators‐activated receptor (PPAR)α and PPARγ. However, the mRNA levels of CPT 1 and adipose triglyceride lipase increased following Zn exposure. On day 40, Zn exposure reduced hepatic mRNA expression of 6PGD, G6PD, ME, FAS, ACCα, ACCβ, HSLa, HSLb, SREBP‐1 and PPARγ but increased mRNA expression of CPT 1, adipose triglyceride lipase and PPARα. General speaking, Zn exposure reduced hepatic lipid content by inhibiting lipogenesis and stimulating lipolysis. For the first time, the present study provided evidence that chronic Zn exposure differentially influenced mRNA expression and activities of genes and enzymes involved in lipogenic and lipolytic metabolism in a duration‐dependent manner, and provided new insight into the relationship between metal elements and lipid metabolism. Copyright © 2015 John Wiley & Sons, Ltd.
       
  • 4‐Nitrophenol exposure alters the AhR signaling pathway and related
           gene expression in the rat liver
    • Abstract: 4‐Nitrophenol (PNP) is well known as an environmental endocrine disruptor. The aim of this study was to clarify the mechanism of PNP‐induced liver damage and determine the regulatory involvement of the aryl hydrocarbon receptor (AhR) signaling pathway and associated gene expression. Immature male Wistar–Imamichi rats (28 days old) were randomly divided into control and PNP groups, which consisted of 1‐ and 3‐day exposure (1 DE and 3 DE, respectively) and 3‐day exposure followed by 3‐day recovery (3 DE + 3 DR), groups. Each group was administered the vehicle or PNP (200 mg kg–1 body weight). The body and liver weight were significantly decreased in the 3 DE group. The mRNA expression levels of estrogen receptor‐α (ERα), glutathione S‐transferase (GST) and AhR exhibited a significant increase in the 1 DE group whereas, in contrast, that of cytochrome P450 (CYP) 1A1 decreased significantly in the 3 DE +3 DR group. AhR and CYP1A1 proteins were detected in the cytoplasm of hepatocytes of the 1 DE and 3 DE +3 DR groups whereas the ERα protein was found in the hepatocyte nuclei of the 1 DE and 3 DE groups. The present study demonstrates that PNP activated the AhR signaling pathway and regulated related CYP1A1 and GST gene expression in the liver. Copyright © 2016 John Wiley & Sons, Ltd.
       
  • Revision of the affinity constant for perchlorate binding to the
           sodium‐iodide symporter based on in vitro and human in vivo data
    • Abstract: A series of previously published physiologically based pharmacokinetic (PBPK) models describe the effect of perchlorate on iodide uptake by the thyroid, with the mechanism being competitive inhibition of iodide transport by the sodium‐iodide symporter (NIS). Hence a key parameter of these models is the affinity of perchlorate for the NIS, characterized as the Michaelis–Menten kinetic constant, Km. However, when model predictions were compared to published results of a human study measuring radio‐iodide uptake (RAIU) inhibition after controlled perchlorate exposures, it was found to only fit the lowest exposure level and underpredicted RAIU inhibition at higher levels. Published in vitro data, in which perchlorate‐induced inhibition of iodide uptake via the NIS was measured, were re‐analyzed. Km for binding of perchlorate to the NIS originally derived from these data, 1.5 μm, had been obtained using Lineweaver–Burk plots, which allow for linear regression but invert the signal–noise of the data. Re‐fitting these data by non‐linear regression of the non‐inverted data yielded a 60% lower value for the Km, 0.59 μm. Substituting this value into the PBPK model for an average adult human significantly improved model agreement with the human RAIU data for exposures
       
  • Development of the Larval Amphibian Growth and Development Assay: effects
           of chronic 4‐tert‐octylphenol or 17β‐trenbolone
           exposure in Xenopus laevis from embryo to juvenile
    • Abstract: The Larval Amphibian Growth and Development Assay (LAGDA) is a globally harmonized test guideline developed by the U.S. Environmental Protection Agency in collaboration with Japan's Ministry of the Environment. The LAGDA was designed to evaluate apical effects of chronic chemical exposure on growth, thyroid‐mediated amphibian metamorphosis and reproductive development. During the validation phase, two well‐characterized endocrine‐disrupting chemicals were tested to evaluate the performance of the initial assay design: xenoestrogen 4‐tert‐octylphenol (tOP) and xenoandrogen 17β‐trenbolone (TB). Xenopus laevis embryos were exposed, in flow‐through conditions, to tOP (nominal concentrations: 0.0, 6.25, 12.5, 25 and 50 µg l–1) or TB (nominal concentrations: 0.0, 12.5, 25, 50 and 100 ng l–1) until 8 weeks post‐metamorphosis, at which time growth measurements were taken, and histopathology assessments were made of the gonads, reproductive ducts, liver and kidneys. There were no effects on growth in either study and no signs of overt toxicity, sex reversal or gonad dysgenesis. Exposure to tOP caused a treatment‐related decrease in circulating thyroxine and an increase in thyroid follicular cell hypertrophy and hyperplasia (25 and 50 µg l–1) during metamorphosis. Müllerian duct development was affected after exposure to both chemicals; tOP exposure caused dose‐dependent maturation of oviducts in both male and female frogs, whereas TB exposure caused accelerated Müllerian duct regression in males and complete regression in >50% of the females in the 100 ng l–1 treatment. Based on these results, the LAGDA performed adequately to evaluate apical effects of chronic exposure to two endocrine‐active compounds and is the first standardized amphibian multiple life stage toxicity test to date. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
       
  • Effects of in vitro exposure to butylparaben and di‐(2 ethylhexyl)
           phthalate, alone or in combination, on ovarian function
    • Abstract: Parabens and phthalates are commercial chemicals widely used in the manufacture of industrial and consumer products frequently found as contaminants in biological fluids. We evaluated the effects of di‐(2‐ethylhexyl) phthalate (DEHP) (ranging from 10–9 to 10–7 m [1–100 nm; 0.39–39 ng ml–1]) and butylparaben (BP) (ranging from 10–8 to 10–5 m [10 nm–10 μm; 1.9 ng ml–1 to 1.9 μg ml–1]), alone and in combination, on isolated mouse preantral follicle and human granulosa cell (hGC) cultures to study direct effects on follicle growth and ovarian steroidogenesis. Our results revealed that, in follicle culture, DEHP and BP attenuate estradiol output but only when present together. DEHP decreases progesterone concentrations in the spent media of hGC cultures, an effect that was attenuated when BP was added together with DEHP. Although changes in steroidogenesis were observed, no effects on follicular development or survival were noted in the culture systems. We suggest that BP and DEHP act with additive effect to decrease estradiol production whereas at later stages of follicle development BP blocks the effect of DEHP in hGCs resulting in decreased progesterone output. Taken together our results suggest that DEHP and BP adversely affect steroidogenesis from the preantral stage onward and the effects of these chemicals are both stage‐dependent and modified by co‐exposure. Copyright © 2016 John Wiley & Sons, Ltd.
       
  • Characterization of three human cell line models for high‐throughput
           neuronal cytotoxicity screening
    • Abstract: More than 75 000 man‐made chemicals contaminate the environment; many of these have not been tested for toxicities. These chemicals demand quantitative high‐throughput screening assays to assess them for causative roles in neurotoxicities, including Parkinson's disease and other neurodegenerative disorders. To facilitate high throughput screening for cytotoxicity to neurons, three human neuronal cellular models were compared: SH‐SY5Y neuroblastoma cells, LUHMES conditionally‐immortalized dopaminergic neurons, and Neural Stem Cells (NSC) derived from human fetal brain. These three cell lines were evaluated for rapidity and degree of differentiation, and sensitivity to 32 known or candidate neurotoxicants. First, expression of neural differentiation genes was assayed during a 7‐day differentiation period. Of the three cell lines, LUHMES showed the highest gene expression of neuronal markers after differentiation. Both in the undifferentiated state and after 7 days of neuronal differentiation, LUHMES cells exhibited greater cytotoxic sensitivity to most of 32 suspected or known neurotoxicants than SH‐SY5Y or NSCs. LUHMES cells were also unique in being more susceptible to several compounds in the differentiating state than in the undifferentiated state; including known neurotoxicants colchicine, methyl‐mercury (II), and vincristine. Gene expression results suggest that differentiating LUHMES cells may be susceptible to apoptosis because they express low levels of anti‐apoptotic genes BCL2 and BIRC5/survivin, whereas SH‐SY5Y cells may be resistant to apoptosis because they express high levels of BCL2, BIRC5/survivin, and BIRC3 genes. Thus, LUHMES cells exhibited favorable characteristics for neuro‐cytotoxicity screening: rapid differentiation into neurons that exhibit high level expression neuronal marker genes, and marked sensitivity of LUHMES cells to known neurotoxicants. Copyright © 2016 John Wiley & Sons, Ltd.
       
  • Lack of genotoxic mechanisms in early‐stage furan‐induced
           hepatocellular tumorigenesis in gpt delta rats
    • Abstract: Furan has been used as an intermediate in the chemical‐manufacturing industry and has been shown to contaminate various foods. Although furan induces hepatocellular tumors in rodents, equivocal results from in vitro and in vivo mutagenicity tests have caused controversy regarding the involvement of genotoxic mechanisms in furan‐induced carcinogenesis. In the present study, to elucidate the possible mechanisms underlying furan‐induced hepatocarcinogenesis, a comprehensive medium‐term analysis was conducted using gpt delta rats treated with furan at carcinogenic doses for 13 weeks. In the liver, the frequencies of gpt and Spi‐ mutants derived mainly from point and deletion mutations, respectively, were not changed, and there were no furan‐specific gpt mutations in furan‐treated rats. In contrast, the number and area of glutathione S‐transferase placental form (GST‐P)‐ positive foci were significantly increased in the high‐dose group. Also, the ratio of PCNA‐positive hepatocytes was significantly elevated in the same group, as supported by significant increases in cyclin d1 and cyclin e1 mRNA levels. Thus, it is highly probable that cell proliferation, but not genotoxic mechanisms, contribute to the development of GST‐P foci in furan‐treated rats. Based on the close relationship between GST‐P and neoplastic hepatocytes, these data allowed us to hypothesize that cell proliferation following signal transduction other than the mitogen‐activated protein kinase (MAPK)/ERK pathway may play a crucial role in early‐stage furan‐induced hepatocarcinogenesis. Copyright © 2016 John Wiley & Sons, Ltd.
       
 
 
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