for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> ENVIRONMENTAL STUDIES (Total: 833 journals)
    - ENVIRONMENTAL STUDIES (762 journals)
    - POLLUTION (23 journals)
    - TOXICOLOGY AND ENVIRONMENTAL SAFETY (39 journals)
    - WASTE MANAGEMENT (9 journals)

ENVIRONMENTAL STUDIES (762 journals)            First | 1 2 3 4 5 6 7 8     

Greenhouse Gas Measurement and Management     Hybrid Journal   (Followers: 1)
Harvard Environmental Law Review     Free   (Followers: 13)
Health Services Management Research     Hybrid Journal   (Followers: 12)
Health, Safety and Environment     Open Access   (Followers: 14)
Hereditas     Open Access   (Followers: 2)
Hidrobiológica     Open Access  
Historia Ambiental Latinoamericana y Caribeña     Open Access   (Followers: 1)
História, Natureza e Espaço - Revista Eletrônica do Grupo de Pesquisa NIESBF     Open Access  
Home Health Care Management & Practice     Hybrid Journal   (Followers: 3)
Horticulture, Environment, and Biotechnology     Hybrid Journal   (Followers: 12)
Human & Experimental Toxicology     Hybrid Journal   (Followers: 9)
Human Ecology     Hybrid Journal   (Followers: 20)
Human Studies     Hybrid Journal   (Followers: 9)
Husserl Studies     Hybrid Journal  
Hydro Nepal : Journal of Water, Energy and Environment     Open Access   (Followers: 2)
Hydrology: Current Research     Open Access   (Followers: 11)
IAMURE International Journal of Ecology and Conservation     Open Access   (Followers: 5)
Ideas in Ecology and Evolution     Open Access   (Followers: 11)
IEEE Transactions on Network and Service Management     Hybrid Journal   (Followers: 15)
IMA Journal of Management Mathematics     Hybrid Journal   (Followers: 1)
Indiana Journal of Global Legal Studies     Full-text available via subscription   (Followers: 1)
Indoor Air     Hybrid Journal   (Followers: 2)
Information Systems Management     Hybrid Journal   (Followers: 17)
Information Technology and Management     Hybrid Journal   (Followers: 11)
Ingeniería Hidráulica y Ambiental     Open Access  
Inhalation Toxicology     Hybrid Journal   (Followers: 9)
Integrated Environmental Assessment and Management     Hybrid Journal   (Followers: 5)
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
Interfaces     Full-text available via subscription   (Followers: 7)
International Aquatic Research     Open Access   (Followers: 4)
International Archives of Occupational and Environmental Health     Hybrid Journal   (Followers: 6)
International Environmental Agreements: Politics, Law and Economics     Hybrid Journal   (Followers: 12)
International Gambling Studies     Hybrid Journal   (Followers: 6)
International Innovation - climate     Open Access  
International innovation. Environment     Open Access  
International Journal of Acarology     Hybrid Journal   (Followers: 1)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 2)
International Journal of African Renaissance Studies - Multi-, Inter- and Transdisciplinarity     Hybrid Journal   (Followers: 2)
International Journal of Agricultural and Environmental Information Systems     Full-text available via subscription   (Followers: 3)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 2)
International Journal of Applied Psychoanalytic Studies     Hybrid Journal   (Followers: 1)
International Journal of Chinese Culture and Management     Hybrid Journal   (Followers: 4)
International Journal of Corrosion     Open Access   (Followers: 13)
International Journal of Critical Infrastructures     Hybrid Journal   (Followers: 3)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 8)
International Journal of Disaster Risk Science     Open Access   (Followers: 13)
International Journal of Ecological Economics and Statistics     Full-text available via subscription  
International Journal of Ecology     Open Access   (Followers: 8)
International Journal of Ecology & Development     Full-text available via subscription   (Followers: 2)
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 2)
International Journal of Environment     Open Access   (Followers: 3)
International Journal of Environment and Health     Hybrid Journal   (Followers: 8)
International Journal of Environment and Pollution     Hybrid Journal   (Followers: 5)
International Journal of Environment and Sustainable Development     Hybrid Journal   (Followers: 17)
International Journal of Environment and Waste Management     Hybrid Journal   (Followers: 7)
International Journal of Environment, Workplace and Employment     Hybrid Journal   (Followers: 4)
International Journal of Environmental Engineering     Hybrid Journal   (Followers: 5)
International Journal of Environmental Health Research     Hybrid Journal   (Followers: 2)
International Journal of Environmental Policy and Decision Making     Hybrid Journal   (Followers: 10)
International Journal of Environmental Protection     Open Access   (Followers: 12)
International Journal of Environmental Research and Public Health     Open Access   (Followers: 18)
International Journal of Environmental Science and Technology     Hybrid Journal   (Followers: 5)
International Journal of Environmental Studies     Hybrid Journal   (Followers: 10)
International Journal of Exergy     Hybrid Journal   (Followers: 4)
International Journal of Forest, Soil and Erosion     Open Access   (Followers: 5)
International Journal of Global Environmental Issues     Hybrid Journal   (Followers: 5)
International Journal of Global Warming     Hybrid Journal   (Followers: 4)
International Journal of Greenhouse Gas Control     Partially Free   (Followers: 6)
International Journal of Health Planning and Management     Hybrid Journal   (Followers: 8)
International Journal of Hygiene and Environmental Health     Hybrid Journal   (Followers: 8)
International Journal of Logistics Research and Applications : A Leading Journal of Supply Chain Management     Hybrid Journal   (Followers: 11)
International Journal of Philosophical Studies     Hybrid Journal   (Followers: 2)
International Journal of Phytoremediation     Hybrid Journal   (Followers: 2)
International Journal of Process Systems Engineering     Hybrid Journal   (Followers: 1)
International Journal of Recycling of Organic Waste in Agriculture     Open Access   (Followers: 2)
International Journal of Reliability and Safety     Hybrid Journal   (Followers: 10)
International Journal of Renewable Energy Development     Open Access   (Followers: 6)
International Journal of Social Sciences and Management     Open Access   (Followers: 2)
International Journal of Soil, Sediment and Water     Open Access   (Followers: 8)
International Journal of Stress Management     Full-text available via subscription   (Followers: 12)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 11)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Materials and Structural Systems     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Society     Hybrid Journal   (Followers: 5)
International Journal of Testing     Hybrid Journal   (Followers: 2)
International Journal of the Commons     Open Access   (Followers: 3)
International Journal of Toxicology     Hybrid Journal   (Followers: 9)
International Journal of Water Resources and Environmental Engineering     Open Access   (Followers: 5)
International Studies in the Philosophy of Science     Hybrid Journal   (Followers: 13)
Interventions : International Journal of Postcolonial Studies     Hybrid Journal   (Followers: 13)
IOP Conference Series: Earth and Environmental Science     Open Access   (Followers: 7)
Iranian Studies     Hybrid Journal   (Followers: 10)
Irish Educational Studies     Hybrid Journal   (Followers: 2)
Irish Journal of Earth Sciences     Full-text available via subscription  
Irish Political Studies     Hybrid Journal   (Followers: 9)
ISLE: Interdisciplinary Studies in Literature and Environment     Hybrid Journal   (Followers: 1)
Isotopes in Environmental and Health Studies     Hybrid Journal   (Followers: 1)
Israel Studies     Full-text available via subscription   (Followers: 5)
Italian Studies     Hybrid Journal   (Followers: 7)
Jahangirnagar University Environmental Bulletin     Open Access  

  First | 1 2 3 4 5 6 7 8     

Journal Cover Journal of Applied Toxicology
  [SJR: 0.799]   [H-I: 53]   [12 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  [1598 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
       
  • Inhibitory effect of cadmium on estrogen signaling in zebrafish brain and
           protection by zinc
    • Abstract: The present study was conducted to assess the effects of Cd exposure on estrogen signaling in the zebrafish brain, as well as the potential protective role of Zn against Cd‐induced toxicity. For this purpose, the effects on transcriptional activation of the estrogen receptors (ERs), aromatase B (Aro‐B) protein expression and molecular expression of related genes were examined in vivo using wild‐type and transgenic zebrafish embryos. For in vitro studies, an ER‐negative glial cell line (U251MG) transfected with different zebrafish ER subtypes (ERα, ERβ1 and ERβ2) was also used. Embryos were exposed either to estradiol (E2), Cd, E2+Cd or E2+Cd+Zn for 72 h and cells were exposed to the same treatments for 30 h. Our results show that E2 treatment promoted the transcriptional activation of ERs and increased Aro‐B expression, at both the protein and mRNA levels. Although exposure to Cd, does not affect the studied parameters when administered alone, it significantly abolished the E2‐stimulated transcriptional response of the reporter gene for the three ER subtypes in U251‐MG cells, and clearly inhibited the E2 induction of Aro‐B in radial glial cells of zebrafish embryos. These inhibitory effects were accompanied by a significant downregulation of the expression of esr1, esr2a, esr2b and cyp19a1b genes compared to the E2‐treated group used as a positive control. Zn administration during simultaneous exposure to E2 and Cd strongly stimulated zebrafish ERs transactivation and increased Aro‐B protein expression, whereas mRNA levels of the three ERs as well as the cyp19a1b remained unchanged in comparison with Cd‐treated embryos. In conclusion, our results clearly demonstrate that Cd acts as a potent anti‐estrogen in vivo and in vitro, and that Cd‐induced E2 antagonism can be reversed, at the protein level, by Zn supplement. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-09T05:45:42.655195-05:
      DOI: 10.1002/jat.3285
       
  • 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
       
  • Issue Information ‐ TOC
    • Pages: 749 - 751
      Abstract: No abstract is available for this article.
      PubDate: 2016-04-14T22:34:15.168559-05:
      DOI: 10.1002/jat.3240
       
  • 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
       
  • Development and application of a human PBPK model for bromodichloromethane
           to investigate the impacts of multi‐route exposure
    • Authors: Elaina M. Kenyon; Christopher Eklund, Teresa Leavens, Rex A. Pegram
      Abstract: As a result of its presence in water as a volatile disinfection byproduct, bromodichloromethane (BDCM), which is mutagenic, poses a potential health risk from exposure via oral, dermal and inhalation routes. We developed a refined human physiologically based pharmacokinetic (PBPK) model for BDCM (including new chemical‐specific human parameters) to evaluate the impact of BDCM exposure during showering and bathing on important measures of internal dose compared with oral exposure. The refined model adequately predicted data from the published literature for oral, dermal and bathing/showering exposures. A liter equivalency approach (L‐eq) was used to estimate BDCM concentration in a liter of water consumed by the oral route that would be required to produce the same internal dose of BDCM resulting from a 20‐min bath or a 10‐min shower in water containing 10 µg l–1 BDCM. The oral liter equivalent concentrations for the bathing scenario were 605, 803 and 5 µg l–1 BDCM for maximum venous blood concentration (Cmax), the area under the curve (AUCv) and the amount metabolized in the liver per hour (MBDCM), respectively. For a 10‐min showering exposure, the oral L‐eq concentrations were 282, 312 and 2.1 µg l–1 for Cmax, AUC and MBDCM, respectively. These results demonstrate large contributions of dermal and inhalation exposure routes to the internal dose of parent chemical reaching the systemic circulation, which could be transformed to mutagenic metabolites in extrahepatic target tissues. Thus, consideration of the contribution of multiple routes of exposure when evaluating risks from water‐borne BDCM is needed, and this refined human model will facilitate improved assessment of internal doses from real‐world exposures. Published 2015. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
      PubDate: 2015-12-09T07:46:54.18612-05:0
      DOI: 10.1002/jat.3269
       
  • Reconstituted high‐density lipoprotein can elevate plasma alanine
           aminotransferase by transient depletion of hepatic cholesterol: role of
           the phospholipid component
    • Abstract: Human apolipoprotein A‐I preparations reconstituted with phospholipids (reconstituted high‐density lipoprotein [HDL]) have been used in a large number of animal and human studies to investigate the physiological role of apolipoprotein A‐I. Several of these studies observed that intravenous infusion of reconstituted HDL might cause transient elevations in plasma levels of hepatic enzymes. Here we describe the mechanism of this enzyme release. Observations from several animal models and in vitro studies suggest that the extent of hepatic transaminase release (alanine aminotransferase [ALT]) correlates with the movement of hepatic cholesterol into the blood after infusion. Both the amount of ALT release and cholesterol movement were dependent on the amount and type of phospholipid present in the reconstituted HDL. As cholesterol is known to dissolve readily in phospholipid, an HDL preparation was loaded with cholesterol before infusion into rats to assess the role of diffusion of cholesterol out of the liver and into the reconstituted HDL. Cholesterol‐loaded HDL failed to withdraw cholesterol from tissues and subsequently failed to cause ALT release. To investigate further the role of cholesterol diffusion, we employed mice deficient in SR‐BI, a transporter that facilitates spontaneous movement of cholesterol between cell membranes and HDL. These mice showed substantially lower movement of cholesterol into the blood and markedly lower ALT release. We conclude that initial depletion of hepatic cholesterol initiates transient ALT release in response to infusion of reconstituted HDL. This effect may be controlled by appropriate choice of the type and amount of phospholipid in reconstituted HDL. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-09T07:10:01.047513-05:
      DOI: 10.1002/jat.3264
       
  • Allopurinol induces innate immune responses through
           mitogen‐activated protein kinase signaling pathways in HL‐60
           cells
    • Authors: Akira Nakajima; Shingo Oda, Tsuyoshi Yokoi
      Abstract: Allopurinol, an inhibitor of xanthine oxidase, is a frequent cause of severe cutaneous adverse reactions (SCARs) in humans, including drug rash with eosinophilia and systemic symptoms, Stevens–Johnson syndrome and toxic epidermal necrolysis. Although SCARs have been suspected to be immune‐mediated, the mechanisms of allopurinol‐induced SCARs remain unclear. In this study, we examined whether allopurinol has the ability to induce innate immune responses in vitro using human dendritic cell (DC)‐like cell lines, including HL‐60, THP‐1 and K562, and a human keratinocyte cell line, HaCaT. In this study, we demonstrate that treatment of HL‐60 cells with allopurinol significantly increased the mRNA expression levels of interleukin‐8, monocyte chemotactic protein‐1 and tumor necrosis factor α in a time‐ and concentration‐dependent manner. Furthermore, allopurinol induced the phosphorylation of mitogen‐activated protein kinases (MAPK), such as c‐Jun N‐terminal kinase and extracellular signal‐regulated kinase, which regulate cytokine production in DC. In addition, allopurinol‐induced increases in cytokine expression were inhibited by co‐treatment with the MAPK inhibitors. Collectively, these results suggest that allopurinol has the ability to induce innate immune responses in a DC‐like cell line through activation of the MAPK signaling pathways. These results indicate that innate immune responses induced by allopurinol might be involved in the development of allopurinol‐induced SCARs. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-07T19:41:27.949835-05:
      DOI: 10.1002/jat.3272
       
  • The minipig as a new model for the evaluation of doxorubicin‐induced
           chronic toxicity
    • Authors: Rosa Anna Manno; Andrea Grassetti, Germano Oberto, Abraham Nyska, Yuval Ramot
      Abstract: Doxorubicin can cause life‐threatening toxic effects in several organs, with cardiotoxicity being the major concern. Although a large number of animal models have been utilized to study doxorubicin toxicity, several restrictions limit their use. Since the Göttingen minipig is an accepted species for non‐clinical safety assessment and translation to man, we aimed at exploring its use as a non‐rodent animal model for safety assessment and regulatory toxicity studies using doxorubicin. Three groups of three males and three females adult Göttingen minipigs received 1.5 mg kg−1, 3/2.3 mg kg−1 or vehicle at intervals of 3 weeks for 7 cycles. Doxorubicin treatment resulted in a dose‐related decrease in the erythrocytes, hemoglobin and hematocrit count, accompanied by leukopenia and thrombocytopenia. Bone marrow smears revealed dose‐related hypocellularity. Urea and creatinine levels were elevated in treated animals, associated with proteinuria and hematuria. Histopathological evaluation detected nephropathy and atrophy of hematopoietic tissues/organs, mucosa of the intestinal tract and male genital tract. Cardiac lesions including chronic inflammation, endocardial hyperplasia, hemorrhage and myxomatous changes were evident in hematoxylin and eosin stains, and evaluation of semi‐thin sections showed the presence of dose‐related vacuolation in the atrial and ventricular cardiomyocytes. Cardiac troponin levels were increased in the high‐dose group, but there was no direct correlation to the severity of the histopathological lesions. This study confirms that the Göttingen minipig has a comparable toxicity profile to humans and considering its anatomical, physiological, genetic and biochemical resemblance to humans, it should be considered as the non‐rodent species of choice for studies on doxorubicin toxicity. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-11-27T23:07:40.695167-05:
      DOI: 10.1002/jat.3266
       
  • Stratum corneum reservoir as a predictive method for in vitro percutaneous
           absorption
    • Authors: Farhaan Hafeez; Audris Chiang, Xiaoying Hui, Hanjiang Zhu, Faraz Kamili, Howard I. Maibach
      Abstract: Interaction between drug and proteins and lipids in stratum corneum (SC) is an important pharmacokinetic parameter in early steps of absorption. Previous in vivo studies showed that the total amount of compound, regardless of properties, penetrating over a 96 h period could be predicted by the amount present in SC 30 min after application by a linear relationship. Validating this linear relationship through in vitro study would facilitate testing of transdermal drug delivery platforms. We aimed to determine in vitro penetration behavior across SC of humans by determining the relationship between quantity present in SC reservoir 30 min after application with 24 h skin absorption and penetration. In this study, use of the SC reservoir effect to predict absorption and penetration of topical compounds is reaffirmed with in vitro models involving human skin. These results indicate the amount in short‐term (30 min) SC reservoir predict long‐term (24 h) skin absorption and penetration, as characterized by statistically significant linear relationships determined via regression. This may be explained by the fact that SC is a rate‐limiting barrier to percutaneous drug transport. After molecules diffuse through SC barrier, passage into deeper dermal layers and systemic uptake occur relatively quickly. These results enable one to measure quantity in SC reservoir shortly after topical application as a proxy for absorption and penetration over longer periods. With respect to drug development and risk assessment of toxic substances, this may simplify assays attempting to quantitate penetration capacity. Further investigation with a larger range of compounds is needed to clarify the observations recorded here. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-11-27T22:10:30.410109-05:
      DOI: 10.1002/jat.3262
       
  • 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.
      PubDate: 2015-11-25T05:10:36.849125-05:
      DOI: 10.1002/jat.3261
       
  • Effects of soap–water wash on human epidermal penetration
    • Abstract: Skin decontamination is a primary interventional method used to decrease dermal absorption of hazardous contaminants, including chemical warfare agents, pesticides and industrial pollutants. Soap and water wash, the most common and readily available decontamination system, may enhance percutaneous absorption through the “wash‐in effect.” To understand better the effect of soap–water wash on percutaneous penetration, and provide insight to improving skin decontamination methods, in vitro human epidermal penetration rates of four C14‐labeled model chemicals (hydroquinone, clonidine, benzoic acid and paraoxon) were assayed using flow‐through diffusion cells. Stratum corneum (SC) absorption rates of these chemicals at various hydration levels (0–295% of the dry SC weights) were determined and compared with the results of the epidermal penetration study to clarify the effect of SC hydration on skin permeability. Results showed accelerated penetration curves of benzoic acid and paraoxon after surface wash at 30 min postdosing. Thirty minutes after washing (60 min postdosing), penetration rates of hydroquinone and benzoic acid decreased due to reduced amounts of chemical on the skin surface and in the SC. At the end of the experiment (90 min postdosing), a soap–water wash resulted in lower hydroquinone penetration, greater paraoxon penetration and similar levels of benzoic acid and clonidine penetration compared to penetration levels in the non‐wash groups. The observed wash‐in effect agrees with the enhancement effect of SC hydration on the SC chemical absorption rate. These results suggest SC hydration derived from surface wash to be one cause of the wash‐in effect. Further, the occurrence of a wash‐in effect is dependent on chemical identity and elapsed time between exposure and onset of decontamination. By reducing chemical residue quantity on skin surface and in the SC reservoir, the soap–water wash may decrease the total quantity of chemical absorbed in the long term; however, the more immediate accelerated absorption of chemical toxins, particularly chemical warfare agents, may be lethal. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-11-15T20:55:30.662883-05:
      DOI: 10.1002/jat.3258
       
  • 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.
      PubDate: 2015-10-28T23:20:42.8128-05:00
      DOI: 10.1002/jat.3234
       
  • Metabolic activation and drug‐induced liver injury: in vitro
           approaches for the safety risk assessment of new drugs
    • First page: 752
      Abstract: Drug‐induced liver injury (DILI) is a significant leading cause of hepatic dysfunction, drug failure during clinical trials and post‐market withdrawal of approved drugs. Many cases of DILI are unexpected reactions of an idiosyncratic nature that occur in a small group of susceptible individuals. Intensive research efforts have been made to understand better the idiosyncratic DILI and to identify potential risk factors. Metabolic bioactivation of drugs to form reactive metabolites is considered an initiation mechanism for idiosyncratic DILI. Reactive species may interact irreversibly with cell macromolecules (covalent binding, oxidative damage), and alter their structure and activity. This review focuses on proposed in vitro screening strategies to predict and reduce idiosyncratic hepatotoxicity associated with drug bioactivation. Compound incubation with metabolically competent biological systems (liver‐derived cells, subcellular fractions), in combination with methods to reveal the formation of reactive intermediates (e.g., formation of adducts with liver proteins, metabolite trapping or enzyme inhibition assays), are approaches commonly used to screen the reactivity of new molecules in early drug development. Several cell‐based assays have also been proposed for the safety risk assessment of bioactivable compounds. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-12-22T02:48:33.92877-05:0
      DOI: 10.1002/jat.3277
       
  • Effects of sulpiride and ethylene glycol monomethyl ether on endometrial
           carcinogenicity in Donryu rats
    • Authors: Yoshikazu Taketa; Kaoru Inoue, Miwa Takahashi, Yohei Sakamoto, Gen Watanabe, Kazuyoshi Taya, Midori Yoshida
      Pages: 769 - 776
      Abstract: Sulpiride and ethylene glycol monomethyl ether (EGME) are known ovarian toxicants that stimulate prolactin (PRL) secretion, resulting in hypertrophy of the corpora lutea and increased progesterone (P4) production. The purpose of the present study was to investigate how the PRL stimulatory agents affected uterine carcinogenesis and to clarify the effects of PRL on endometrial adenocarcinoma progression in rats. Ten‐week‐old female Donryu rats were treated once with N‐ethyl‐N′‐nitro‐N‐nitrosoguanidine (20 mg kg−1), followed by treatment with sulpiride (200 ppm) or EGME (1250 ppm) from 11 weeks of age to 12 months of age. Sulpiride treatment inhibited the incidence of uterine adenocarcinoma and precancerous lesions of atypical endometrial hyperplasia, whereas EGME had no effect on uterine carcinogenesis. Sulpiride markedly prevented the onset of persistent estrus throughout the study period, and EGME delayed and inhibited the onset of persistent estrus. Moreover, sulpiride‐treated animals showed high PRL and P4 serum levels without changes in the levels of estradiol‐17β, low uterine weights and histological luteal cell hypertrophy. EGME did not affect serum PRL and P4 levels. These results suggest that the prolonged low estradiol‐17β to P4 ratio accompanied by persistent estrous cycle abnormalities secondary to the luteal stimulatory effects of PRL may explain the inhibitory effects of sulpiride on uterine carcinogenesis in rats. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-07-14T10:39:16.58795-05:0
      DOI: 10.1002/jat.3206
       
  • Antimicrobial agent triclosan is a proton ionophore uncoupler of
           mitochondria in living rat and human mast cells and in primary human
           keratinocytes
    • Authors: Lisa M. Weatherly; Juyoung Shim, Hina N. Hashmi, Rachel H. Kennedy, Samuel T. Hess, Julie A. Gosse
      Pages: 777 - 789
      Abstract: Triclosan (TCS) is an antimicrobial used widely in hospitals and personal care products, at ~10 mm. Human skin efficiently absorbs TCS. Mast cells are ubiquitous key players both in physiological processes and in disease, including asthma, cancer and autism. We previously showed that non‐cytotoxic levels of TCS inhibit degranulation, the release of histamine and other mediators, from rat basophilic leukemia mast cells (RBL‐2H3), and in this study, we replicate this finding in human mast cells (HMC‐1.2). Our investigation into the molecular mechanisms underlying this effect led to the discovery that TCS disrupts adenosine triphosphate (ATP) production in RBL‐2H3 cells in glucose‐free, galactose‐containing media (95% confidence interval EC50 = 7.5–9.7 µm), without causing cytotoxicity. Using these same glucose‐free conditions, 15 µm TCS dampens RBL‐2H3 degranulation by 40%. The same ATP disruption was found with human HMC‐1.2 cells (EC50 4.2–13.7 µm), NIH‐3 T3 mouse fibroblasts (EC50 4.8–7.4 µm) and primary human keratinocytes (EC50 3.0–4.1 µm) all with no cytotoxicity. TCS increases oxygen consumption rate in RBL‐2H3 cells. Known mitochondrial uncouplers (e.g., carbonyl cyanide 3‐chlorophenylhydrazone) previously were found to inhibit mast cell function. TCS‐methyl, which has a methyl group in place of the TCS ionizable proton, affects neither degranulation nor ATP production at non‐cytotoxic doses. Thus, the effects of TCS on mast cell function are due to its proton ionophore structure. In addition, 5 µm TCS inhibits thapsigargin‐stimulated degranulation of RBL‐2H3 cells: further evidence that TCS disrupts mast cell signaling. Our data indicate that TCS is a mitochondrial uncoupler, and TCS may affect numerous cell types and functions via this mechanism. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-07-23T21:48:50.906798-05:
      DOI: 10.1002/jat.3209
       
  • Perfluorinated chemicals, PFOS and PFOA, enhance the estrogenic effects of
           17β‐estradiol in T47D human breast cancer cells
    • Authors: Pacharapan Sonthithai; Tawit Suriyo, Apinya Thiantanawat, Piyajit Watcharasit, Mathuros Ruchirawat, Jutamaad Satayavivad
      Pages: 790 - 801
      Abstract: Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are the two most popular surfactants among perfluorinated compounds (PFCs), with a wide range of uses. Growing evidence suggests that PFCs have the potential to interfere with estrogen homeostasis, posing a risk of endocrine‐disrupting effects. This in vitro study aimed to investigate the estrogenic effect of these compounds on T47D hormone‐dependent breast cancer cells. PFOS and PFOA (10−12 to 10−4 M) were not able to induce estrogen response element (ERE) activation in the ERE luciferase reporter assay. The ERE activation was induced when the cells were co‐incubated with PFOS (10−10 to 10−7 M) or PFOA (10−9 to 10−7 M) and 1 nM of 17β‐estradiol (E2). PFOS and PFOA did not modulate the expression of estrogen‐responsive genes, including progesterone (PR) and trefoil factor (pS2), but these compounds enhanced the effect of E2‐induced pS2 gene expression. Neither PFOS nor PFOA affected T47D cell viability at any of the tested concentrations. In contrast, co‐exposure with PFOS or PFOA and E2 resulted in an increase of E2‐induced cell viability, but no effect was found with 10 ng ml−1 EGF co‐exposure. Both compounds also intensified E2‐dependent growth in the proliferation assay. ERK1/2 phosphorylation was increased by co‐exposure with PFOS or PFOA and E2, but not with EGF. Collectively, this study shows that PFOS and PFOA did not possess estrogenic activity, but they enhanced the effects of E2 on estrogen‐responsive gene expression, ERK1/2 activation and the growth of the hormone‐deprived T47D cells. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-08-03T03:06:33.538916-05:
      DOI: 10.1002/jat.3210
       
  • Aryl hydrocarbon receptor knockout rats are insensitive to the
           pathological effects of repeated oral exposure to
           2,3,7,8‐tetrachlorodibenzo‐p‐dioxin
    • Authors: Joshua A. Harrill; Debra Layko, Abraham Nyska, Renee R. Hukkanen, Rosa Anna Manno, Andrea Grassetti, Marie Lawson, Greg Martin, Robert A. Budinsky, J. Craig Rowlands, Russell S. Thomas
      Pages: 802 - 814
      Abstract: Sustained activation of the aryl hydrocarbon receptor (AHR) is believed to be the initial key event in AHR receptor‐mediated tumorigenesis in the rat liver. The role of AHR in mediating pathological changes in the liver prior to tumor formation was investigated in a 4‐week, repeated‐dose study using adult female wild‐type (WT) and AHR knockout (AHR‐KO) rats treated with 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD). Beginning at 8 weeks of age, AHR‐KO and WT rats were dosed by oral gavage with varying concentrations of TCDD (0, 3, 22, 100, 300 and 1000 ng kg−1 day−1). Lung, liver and thymus histopathology, hematology, serum chemistry and the distribution of TCDD in liver and adipose tissue were examined. Treatment‐related increases in the severity of liver and thymus pathology were observed in WT, but not AHR‐KO rats. In the liver, these included hepatocellular hypertrophy, bile duct hyperplasia, multinucleated hepatocytes and inflammatory cell foci. A loss of cellularity in the thymic cortex and thymic atrophy was observed. Treatment‐related changes in serum chemistry parameters were also observed in WT, but not AHR‐KO rats. Finally, dose‐dependent accumulation of TCDD was observed primarily in the liver of WT rats and primarily in the adipose tissue of AHR‐KO rats. The results suggest that AHR activation is the initial key event underlying the progression of histological effects leading to liver tumorigenesis following TCDD treatment. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-08-17T03:18:18.106857-05:
      DOI: 10.1002/jat.3211
       
  • Sensitive periods for 17β‐estradiol exposure during immune
           system development in sea bass head kidney
    • Pages: 815 - 826
      Abstract: An increasing body of evidence suggests that sex steroids play an important role in the development and regulation of vertebrate immune defense. Therefore, compounds with estrogenic activity may influence the immune system via receptor‐mediated pathways. The presence of estrogen receptors in immune cells and organs during the early stages of development may indicate that female steroid hormones are involved in the maturation of the fish immune system. This is of particular importance, as some marine fish are probably exposed to sources of exogenous estrogens while they reside in their estuarine nursery grounds. In this study, the influence of 17β‐estradiol (E2) on estrogen receptor and cytokine gene expression was assessed in juvenile sea bass (Dicentrarchus labrax) together with characterization of the head kidney leukocyte populations and corresponding phagocytic activity during organ regionalization from 98 to 239 dph. E2 exposure, beginning at 90 dph resulted in indirect and delayed modifications of interleukin 1β and estrogen receptor α gene expression, which may affect B‐lymphocyte proliferation in the sea bass head kidney. The E2 treatment of 120 dph fish led to an increase in estrogen receptor β2 and a decrease in transforming growth factor β1 gene expression, which coincided with decreased phagocytic activity of head kidney lymphocytes and monocytes/macrophages. Additionally, these changes were observed during developmental periods described as critical phases for B‐lymphocyte development in mammals. Consequently, exogenous estrogens have the potential to modify the innate immune response in juvenile sea bass and to exert detrimental effects on head kidney development. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-08-16T21:42:45.661493-05:
      DOI: 10.1002/jat.3215
       
  • Altered expression of histone deacetylases, inflammatory cytokines and
           contractile‐associated factors in uterine myometrium of Long Evans
           rats gestationally exposed to benzo[a]pyrene
    • Pages: 827 - 835
      Abstract: Etiology of preterm birth (PTB) is multifactorial; therefore, decreasing the incidence of PTB is a major challenge in the field of obstetrics. Epidemiological studies have reported an association between toxicants and PTB. However, there are no studies on the role of benzo[a]pyrene (BaP), an environmental toxicant, in the incidence of PTB. We first assessed the effects of BaP (150 and 300 µg kg–1 body weight) dosed via gavage from day 14 to 17 of pregnancy on gestation length in Long Evans rats. We further assessed the histopathology of the uterus, expression of inflammatory cytokines, contractile‐associated factors, histone deacetylases (HDACs) and NFқB‐p65 in myometrium collected on day 22 postpartum versus vehicle‐treated controls. In our study, rats exposed to BaP delivered prematurely (P < 0.05) compared to control. Hematoxylin and eosin staining of uterus showed squamous metaplasia, glandular and stromal hyperplasia in BaP‐exposed rats versus control. The concentrations of BaP metabolites measured by high‐pressure liquid chromatography were higher in uterine myometrium of BaP‐exposed rats while they were undetectable in controls. Quantitative real‐time polymerase chain reaction showed significant increases in mRNA expression of interleukin‐1β and ‐8, tumor necrosis factor‐α, connexin 43, cyclo‐oxygenase‐2 and prostaglandin F2α receptor as compared to controls (P < 0.05). Western blot analysis revealed that BaP exposure caused decreases in class I HDACs 1 and 3 and increases in class II HDAC 5, cyclo‐oxygenase‐2 and nuclear translocation of NFκB‐p65 relative to controls. Our results suggest that gestational exposure to BaP increases incidence of PTB through epigenetic changes that causes increases in the expression of contractile‐associated factors through the NFκB pathway. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-09-11T01:37:09.353576-05:
      DOI: 10.1002/jat.3216
       
  • Human ketosteroid receptors interact with hazardous phthalate plasticizers
           and their metabolites: an in silico study
    • Authors: M. K. Sarath Josh; S. Pradeep, K. S. Vijayalekshmy Amma, R. Sudha Devi, S. Balachandran, M. N. Sreejith, Sailas Benjamin
      Pages: 836 - 843
      Abstract: Phthalic acid esters or phthalates are ubiquitous environmental pollutants known for their adverse health effects in test animals and, of late, in humans. Thus, in this molecular docking study – using Glide (Schrödinger) – the molecular interactions of 31 ligands, including 12 diphthalates, their monophthalates and phthalic acid with selected human ketosteroid receptors, i.e., androgen (hAR), progesterone (hPR) and glucocorticoid (hGR) receptors were explored and their binding affinities were compared with that of corresponding natural steroids and a known endocrine disrupting xenobiotic, bisphenol A (BPA). Mostly, diphthalates and monophthalates showed the potential for antisteroidal activity by interacting with hAR, hPR and hGR. Of them, diphenyl phthalate showed the highest G score (–7.70 kcal mol–1) with hAR, and the crucial amino acid (aa) residues in the ligand binding domain (LBD) of this receptor involved in the molecular interactions were Phe 764, Leu 704, Asn 705 and Thr 877. The mono‐iso‐decyl phthalate showed the highest G score (–8.36) with the hPR, and the crucial aa residues in the LBD interactions were Arg 766 Gln 725 and Phe 778. The mono‐iso‐decyl phthalate also showed more affinity (–8.44) towards hGR than the natural ligand, and the aa residues in the LBD interactions were Gln 570 and Met 604. In addition to these, some other phthalates established comparable interactions with certain aa residues located in the LBD of these receptors, which resulted in higher G scores. Contrastingly, BPA and some natural ligands tested in this study showed lower G scores with these receptors than certain phthalates reported herein, i.e., certain phthalates are more toxic than the proven toxic BPA. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-08-24T20:58:14.890977-05:
      DOI: 10.1002/jat.3221
       
  • Thyroid endocrine disruption of acetochlor on zebrafish (Danio rerio)
           larvae
    • Authors: Mei Yang; Jingjin Hu, Shuying Li, Youning Ma, Wenjun Gui, Guonian Zhu
      First page: 844
      Abstract: The herbicide acetochlor is widely used and detected in the environment and biota, and has been suspected to disrupt the thyroid endocrine system, but underlying mechanisms have not yet been clarified. In the present study, zebrafish larvae (7 days post‐fertilization) were exposed to a series concentration of acetochlor (0, 1, 3, 10, 30, 100 and 300 µg l−1) within a 14‐day window until 21 days post‐fertilization. Thyroid hormones and mRNA expression profiles of genes involved in the hypothalamic–pituitary–thyroid (HPT) axis were analyzed. Exposure to the positive control, 3,5,3′‐triiodothyronine (T3), altered the mRNA expression, suggesting that the HPT axis in the critical window of zebrafish responded to chemical exposure and could be used to evaluate the effects of chemicals on the thyroid endocrine system. The mRNA expressions of genes involved in thyroid hormone synthesis (tshβ, slc5a5 and tpo) were upregulated significantly with acetochlor treatment, which might be responsible for the increased thyroxine concentrations. The downregulation of genes related to thyroid hormone metabolism (dio1 and ugt1ab) and transport (ttr) in zebrafish larvae exposed to acetochlor might further explain the increased thyroxine levels and decreased T3 levels. The mRNA expression of the thyroid hormone receptor (trα) was also upregulated upon acetochlor exposure. Results suggested that acetochlor altered mRNA expression of the HPT axis‐related genes and changed the whole body thyroid hormone levels in zebrafish larvae. It demonstrated that acetochlor could cause endocrine disruption of the thyroid system by simulating the biological activity of T3. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-09-23T07:03:38.912914-05:
      DOI: 10.1002/jat.3230
       
  • Transcriptional and morphological effects of tamoxifen on the early
           development of zebrafish (Danio rerio)
    • Authors: Liang Xia; Liang Zheng, Jun Liang Zhou
      First page: 853
      Abstract: Tamoxifen is a widely used anticancer drug with both an estrogen agonist and antagonist effect. This study focused on its endocrine disrupting effect, and overall environmental significance. Zebrafish embryos were exposed to different concentrations (0.5, 5, 50 and 500 µg l–1) of tamoxifen for 96 h. The results showed a complex effect of tamoxifen on zebrafish embryo development. For the 500 µg l–1 exposure group, the heart rate was decreased by 20% and mild defects in caudal fin and skin were observed. Expressions of a series of genes related to endocrine and morphological changes were subsequently tested through quantitative real‐time polymerase chain reaction. Bisphenol A as a known estrogen was also tested as an endocrine‐related comparison. Among the expression of endocrine‐related genes, esr1, ar, cyp19a1b, hsd3b1 and ugt1a1 were all increased by tamoxifen exposure, similar to bisphenol A. The cyp19a1b is a key gene that controls estrogen synthesis. Exposure to 0.5, 5, 50 and 500 µg l–1 of tamoxifen caused upregulation of cyp19a1b expression to 152%, 568%, 953% and 2024% compared to controls, higher than the effects from the same concentrations of bisphenol A treatment, yet vtg1 was suppressed by 24% from exposure to 500 µg l–1 tamoxifen. The expression of metabolic‐related genes such as cyp1a, cyp1c2, cyp3a65, gpx1a, gstp1, gsr and genes related to observed morphological changes such as krt17 were also found to be upregulated by high concentrations of tamoxifen. These findings indicated the potential environmental effect of tamoxifen on teleost early development. Copyright © 2015 John Wiley & Sons, Ltd.
      PubDate: 2015-11-20T03:32:35.122293-05:
      DOI: 10.1002/jat.3257
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2015