Grace E Kissling

National Institutes of Health, Maryland, United States

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Publications (176)

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    [Show abstract] [Hide abstract] ABSTRACT: Background The phytoestrogen, genistein at low doses nongenomically activates mitogen-activated protein kinase p44/42 (MAPKp44/42) via estrogen receptor alpha (ERα) leading to proliferation of human uterine leiomyoma cells. In this study, we evaluated if MAPKp44/42 could activate downstream effectors such as mitogen- and stress-activated protein kinase 1 (MSK1), which could then epigenetically modify histone H3 by phosphorylation following a low dose (1 μg/ml) of genistein. ResultsUsing hormone-responsive immortalized human uterine leiomyoma (ht-UtLM) cells, we found that genistein activated MAPKp44/42 and MSK1, and also increased phosphorylation of histone H3 at serine10 (H3S10ph) in ht-UtLM cells. Colocalization of phosphorylated MSK1 and H3S10ph was evident by confocal microscopy in ht-UtLM cells (r = 0.8533). Phosphorylation of both MSK1and H3S10ph was abrogated by PD98059 (PD), a MEK1 kinase inhibitor, thereby supporting genistein’s activation of MSK1 and Histone H3 was downstream of MAPKp44/42. In proliferative (estrogenic) phase human uterine fibroid tissues, phosphorylated MSK1 and H3S10ph showed increased immunoexpression compared to normal myometrial tissues, similar to results observed in in vitro studies following low-dose genistein administration. Real-time RT-PCR arrays showed induction of growth-related transcription factor genes, EGR1, Elk1, ID1, and MYB (cMyb) with confirmation by western blot, downstream of MAPK in response to low-dose genistein in ht-UtLM cells. Additionally, genistein induced associations of promoter regions of the above transcription factors with H3S10ph as evidenced by Chromatin Immunoprecipitation (ChIP) assays, which were inhibited by PD. Therefore, genistein epigenetically modified histone H3 by phosphorylation of serine 10, which was regulated by MSK1 and MAPK activation. Conclusion Histone H3 phosphorylation possibly represents a mechanism whereby increased transcriptional activation occurs following low-dose genistein exposure.
    Full-text Article · Dec 2016 · Cell Communication and Signaling
  • [Show abstract] [Hide abstract] ABSTRACT: The potential of chemicals to alter susceptibility to mammary tumor formation is often assessed using a carcinogen-induced study design in various rat strains. The rate of mammary gland (MG) development must be considered so that the timing of carcinogen administration is impactful. In this study, in situ MG development was assessed in females of the Harlan Sprague-Dawley (Hsd:SD), Charles River Sprague-Dawley (Crl:SD), and Charles River Long-Evans (Crl:LE) rat strains at postnatal days 25, 33, and 45. Development was evaluated by physical assessment of growth parameters, developmental scoring, and quantitative morphometric analysis. Although body weight (BW) was consistently lower and day of vaginal opening (VO) occurred latest in female Hsd:SD rats, they exhibited accelerated pre- and peripubertal MG development compared to other strains. Glands of Crl:SD and Crl:LE rats exhibited significantly more terminal end buds (TEBs) and TEB/mm than Hsd:SD rats around the time of VO. These data suggest a considerable difference in the rate of MG development across commonly used strains, which is independent of BW and timing of VO. In mammary tumor induction studies employing these strains, administration of the carcinogen should be timed appropriately, based on strain, to specifically target the peak of TEB occurrence.
    Article · Sep 2016 · Toxicologic Pathology
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    Georgia K. Roberts · Suramya Waidyanatha · Grace E. Kissling · [...] · Chad R. Blystone
    [Show abstract] [Hide abstract] ABSTRACT: Butyl paraben (BPB) is an antimicrobial used in a variety of consumer products. Due to widespread human exposure and reported estrogenic activity, the National Toxicology Program quantified internal exposure during critical periods of development. Time-mated female Hsd:Sprague Dawley SD rats were administered 0, 1500, 5000 or 15000 ppm BPB via NIH-07 feed, ad libitum, from gestation day (GD) 6 to postnatal day (PND) 28. Dam plasma, amniotic fluid and fetuses were collected on GD18 and pup and dam plasma were collected on PNDs 4, 10, 14, 21 and 28 and analyzed for free (unconjugated) and total (unconjugated and conjugated) BPB using liquid chromatography-tandem mass spectrometry. Free BPB was below the limit of quantitation in fetuses (LOQ 1.91 ng BPB/g fetus) and amniotic fluid (LOQ 0.17 ng BPB/mL amniotic fluid) at 1500 ppm. Analyte levels in amniotic fluid were less than 1% of maternal plasma, suggesting limited placental transfer. Total BPB in PND4 pup plasma was less than 5% of dam plasma in all exposure groups, suggesting low lactational transfer. However, at nearly all time points and exposure groups, there were higher levels of free BPB in pup versus dam plasma, suggesting limited conjugation in pups. Pup conjugation of BPB was age-dependent, not reaching the percent-conjugation in dams ( > 99%) until PNDs 21 to 28. These data illustrate low placental and lactational transfer of dietary BPB and that poor conjugation in pups during early lactation results in higher exposure to free BPB in pups compared to dams.
    Full-text Article · Sep 2016 · Toxicology Reports
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    [Show abstract] [Hide abstract] ABSTRACT: Metalworking fluids (MWFs) are complex formulations designed for effective lubricating, cooling, and cleaning tools and parts during machining operations. Adverse health effects such as respiratory symptoms, dermatitis, and cancer have been reported in workers exposed to MWFs. Several constituents of MWFs have been implicated in toxicity and have been removed from the formulations over the years. However, animal studies with newer MWFs demonstrate that they continue to pose a health risk. This investigation examines the hypothesis that unrecognized health hazards exist in currently marketed MWF formulations that are presumed to be safe based on hazard assessments of individual ingredients. In vivo 13-week inhalation studies were designed to characterize and compare the potential toxicity of four MWFs: Trim VX, Cimstar 3800, Trim SC210, and Syntilo 1023. Male and female Wistar Han rats or Fischer 344N/Tac rats and B6C3F1/N mice were exposed to MWFs via whole-body inhalation at concentrations of 0, 25, 50, 100, 200, or 400 mg/m3 for 13 weeks, after which, survival, body and organ weights, hematology and clinical chemistry, histopathology, and genotoxicity were assessed following exposure. Although high concentrations were used, survival was not affected and toxicity was primarily within the respiratory tract of male and female rats and mice. Minor variances in toxicity were attributed to differences among species as well as in the chemical components of each MWF. Pulmonary fibrosis was present only in rats and mice exposed to Trim VX. These data confirm that newer MWFs have the potential to cause respiratory toxicity in workers who are repeatedly exposed via inhalation.
    Full-text Article · Jun 2016 · Toxicology and Industrial Health
  • [Show abstract] [Hide abstract] ABSTRACT: Tungsten is a naturally occurring, high-tensile strength element that has been used in a number of consumer products. Tungsten has been detected in soil, waterways, groundwater, and human tissue and body fluids. Elevated levels of tungsten in urine were reported for populations exposed to tungstate in drinking water in areas where natural tungsten formations were prevalent. Published reports indicated that sodium tungstate may modulate hematopoiesis, immune cell populations, and immune responses in rodent models. The objective of this study was to assess potential immunotoxicity of sodium tungstate dihydrate (STD), a drinking water contaminant. Female B6C3F1/N mice received 0–2000 mg STD/L in their drinking water for 28 d, and were evaluated for effects on immune cell populations in spleen and bone marrow, and humoral-mediated, cell-mediated, and innate immunity. Three different parameters of cell-mediated immunity were similarly affected at 1000 mg STD/L. T-cell proliferative responses against allogeneic leukocytes and anti-CD3 were decreased 32%, and 21%, respectively. Cytotoxic T-lymphocyte activity was decreased at all effector:target cell ratios examined. At 2000 mg STD/L, the absolute numbers of CD3+ T-cell progenitor cells in bone marrow were increased 86%, but the alterations in B-lymphocyte and other progenitor cells were not significant. There were no effects on bone marrow DNA synthesis or colony forming capabilities. STD-induced effects on humoral-mediated immunity, innate immunity, and splenocyte sub-populations were limited. Enhanced histopathology did not detect treatment-related lesions in any of the immune tissues. These data suggest exposure to STD in drinking water may adversely affect cell-mediated immunity.
    Article · May 2016 · Journal of Immunotoxicology
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    Full-text Dataset · Apr 2016
  • [Show abstract] [Hide abstract] ABSTRACT: Cumene hydroperoxide (CHP) is a high production volume chemical that is used to generate phenol and acetone. Dermal exposure to CHP was hypothesized to result in systemic tissue toxicity, production of free radicals, and consequent decrease in plasma antioxidant levels. To evaluate the hypothesis and characterize the toxicity of CHP, male and female B6C3F1/N mice and F344/N rats were exposed to varying doses of CHP applied topically for 14 or 90 days. No significant changes in survival or body weight of mice and rats were observed following 14 days of exposure. However, 90 days of CHP exposure at the high dose (12 mg/kg) triggered a significant decrease (−15%) in the body weight of the male rat group only. Irritation of the skin was observed at the site of application and was characterized by inflammation and epidermal hyperplasia. In treated animals, histology of liver tissue, free radical generation, and antioxidant levels in blood plasma were not significantly changed as compared to the corresponding controls. Consistent with the lack of systemic damage, no increase in micronucleated erythrocytes was seen in peripheral blood. In conclusion, topical CHP application caused skin damage only at the application site and did not cause systemic tissue impairment.
    Article · Mar 2016 · Toxicologic Pathology
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    [Show abstract] [Hide abstract] ABSTRACT: Chronic oral treatment of tetrabromobisphenol A (TBBPA) to female Wistar Han rats resulted in increased incidence of cell proliferation at 250 mg/kg and tumor formation in the uterus at higher doses. The present study was designed to test the hypothesis that disruption of estrogen homeostasis was a major mode-of-action for the observed effects. Biological changes were assessed in serum, liver, and the proximal (nearest the cervix) and distal (nearest the ovaries) sections of the uterine horn of Wistar Han rats 24 h following administration of the last of five daily oral doses of 250 mg/kg. Expression of genes associated with receptors, biosynthesis, and metabolism of estrogen was altered in the liver and uterus. TBBPA treatment also resulted in changes in expression of genes associated with cell division and growth. Changes were also observed in the concentration of thyroxine in serum and in expression of genes in the liver and uterus associated with thyroid hormone receptors. Differential expression of some genes was tissue-dependent or specific to tissue location in the uterus. The biological responses observed in the present study support the hypothesis that perturbation of estrogen homeostasis is a major mode-of-action for TBBPA-mediated cell proliferation and tumorigenesis previously observed in the uterus of TBBPA-treated Wistar Han rats.
    Full-text Article · Mar 2016 · Toxicology and Applied Pharmacology
  • Sheba R Churchill · Daniel L Morgan · Grace E Kissling · [...] · Angela P King-Herbert
    [Show abstract] [Hide abstract] ABSTRACT: The goal of this study was to determine whether the use of nesting material or polycarbonate shelters as enrichment devices would have an impact on end points commonly measured during the conduct of the National Toxicology Program (NTP) 13-week studies. The study design was consistent with the NTP 13-week toxicity studies. Harlan Sprague-Dawley (HSD) rats and their offspring and B6C3F1/N mice were assigned to control (unenriched) and enriched experimental groups. Body weight, food and water consumption, behavioral observations, fecal content, clinical pathology, gross pathology, organ weights, and histopathology were evaluated. Enriched male mice and male and female rats exhibited decreased feed intake without a subsequent decrease in body weight; this may have been the result of the nesting material reducing the effect of cold stress, thereby allowing for more efficient use of feed. There were statistical differences in some hematological parameters; however, these were not considered physiologically relevant since all values were within the normal range. Gross pathology and histopathological findings were background changes and were not considered enrichment-related. Nesting material and shelters were used frequently and consistently and allowed animals to display species-typical behavior. There was no significant impact on commonly measured end points in HSD rats and B6C3F1/N mice given enrichment devices.
    Article · Feb 2016 · Toxicologic Pathology
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    David B Resnik · Ana M Tyler · Jennifer R Black · Grace Kissling
    [Show abstract] [Hide abstract] ABSTRACT: We analysed the authorship policies of a random sample of 600 journals from the Journal Citation Reports database. 62.5% of the journals we sampled had an authorship policy. Having an authorship policy was positively associated with impact factor. Journals from the biomedical sciences and social sciences/humanities were more likely to have an authorship policy than journals from the physical sciences, engineering or mathematical sciences. Among journals with a policy, the most frequent type of policy was guidance on criteria for authorship (99.7%); followed by guidance on acknowledgments (97.3%); requiring that authors make substantial contributions to the research (94.7%); requiring that authors be accountable for the research as a whole (84.8%); guidance on changes in authorship (77.9%); requiring that authors give final approval to the manuscript (77.6%); requiring that authors draft or critically revise the manuscript (71.7%); providing guidance on corporate authorship (58.9%); prohibiting gift, guest or ghost authorship (31.7%); requiring authors to describe their contributions (5.3%); limiting the number of authors for some types of articles (4.0%) and requiring authors to be accountable for their part in the research (1.1%). None of the policies addressed equal contribution statements. Journals that do not have authorship policies should consider adopting or developing ones.
    Full-text Article · Dec 2015 · Journal of medical ethics
  • Kristie Mozzachio · Alicia B Moore · Grace E Kissling · Darlene Dixon
    [Show abstract] [Hide abstract] ABSTRACT: Uterine leiomyomas in miniature pet pigs occur similarly to those in women with regard to frequency, age, parity, and cycling. Clinical signs, gross, and histologic features of the porcine tumors closely resemble uterine leiomyomas (fibroids) in women. Although fibroids are hormonally responsive in women, the roles of estrogen and progesterone have not been fully elucidated. In this study, immunohistochemistry was used to assess the expression of the steroid hormone receptors, estrogen receptor alpha (ER-α), estrogen receptor beta (ER-β) and progesterone receptor (PR), and cell proliferation markers, proliferating cell nuclear antigen (PCNA) and Ki-67 in tumor and matched myometrial tissues sampled from miniature pigs. A "quickscore" method was used to determine receptor expression and labeling indices were calculated for the markers. ER-α/β and PR were localized to the nuclei of smooth muscle cells in both tissues. PR expression was intense and diffuse throughout all tissues, with correlation between tumors and matched myometria. Conversely, ER-α expression was variable between the myometrial and tumor tissues, as well as between animals. ER-β expression was low. PCNA and Ki-67 were localized to the nucleus and expression varied among tumors; however, normal tissues were overall negative. These findings support further investigation into the use of the miniature pig as a model of fibroids in women.
    Article · Dec 2015 · Toxicologic Pathology
  • Yuval Ramot · Urmila P Kodavanti · Grace E Kissling · [...] · Abraham Nyska
    [Show abstract] [Hide abstract] ABSTRACT: Rodent models of cardiovascular diseases (CVD) and metabolic disorders are used for examining susceptibility variations to environmental exposures. However, cross-model organ pathologies and clinical manifestations are often not compared. We hypothesized that genetic CVD rat models will exhibit baseline pathologies and will thus express varied lung response to acute ozone exposure. Male 12-14-week-old healthy Wistar Kyoto (WKY), Wistar (WIS), and Sprague-Dawley (SD) rats and CVD-compromised spontaneously hypertensive (SH), fawn-hooded hypertensive (FHH), stroke-prone SH (SHSP), obese SH heart-failure (SHHF), obese diabetic JCR (JCR) rats were exposed to 0.0, 0.25, 0.5, or 1.0 ppm ozone for 4 h and clinical biomarkers, and lung, heart and kidney pathologies were compared immediately following (0-h) or 20-h later. Strain differences were observed between air-exposed CVD-prone and WKY rats in clinical biomarkers and in kidney and heart pathology. Serum cholesterol was higher in air-exposed obese SHHF and JCR compared to other air-exposed strains. Ozone did not produce lesions in the heart or kidney. CVD-prone and SD rats demonstrated glomerulopathy and kidney inflammation (WKY = WIS = SH < SD = SHSP < SHHF < JCR = FHH) regardless of ozone. Cardiac myofiber degeneration was evident in SH, SHHF, and JCR, while only JCR tends to have inflammation in coronaries. Lung pathology in air-exposed rats was minimal in all strains except JCR. Ozone induced variable alveolar histiocytosis and bronchiolar inflammation; JCR and SHHF were less affected. This study provides a comparative account of the clinical manifestations of disease and early-life organ pathologies in several rat models of CVD and their differential susceptibility to lung injury from air pollutant exposure.
    Article · Dec 2015 · Inhalation Toxicology
  • Berran Yucesoy · Grace E Kissling · Victor J Johnson · [...] · David I Bernstein
    [Show abstract] [Hide abstract] ABSTRACT: Objective: To investigate whether genetic variants of N-acetyltransferase (NAT) genes are associated with diisocyanate asthma (DA). Methods: The study population consisted of 354 diisocyanate-exposed workers. Genotyping was performed using a 5'-nuclease polymerase chain reaction assay. Results: The NAT2 rs2410556 and NAT2 rs4271002 variants were significantly associated with DA in the univariate analysis. In the first logistic regression model comparing DA+ and asymptomatic worker groups, the rs2410556 (P = 0.004) and rs4271002 (P < 0.001) single nucleotide polymorphisms and the genotype combination, NAT2 rs4271002*NAT1 rs11777998, showed associations with DA risk (P = 0.014). In the second model comparing DA+ and DA- groups, NAT2 rs4271002 variant and the combined genotype, NAT1 rs8190845*NAT2 rs13277605, were significantly associated with DA risk (P = 0.022, P = 0.036, respectively). Conclusions: These findings suggest that variations in the NAT2 gene and their interactions contribute to DA susceptibility.
    Article · Dec 2015 · Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine
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    David B Resnik · J.L. Ariansen · Jaweria Jamal · Grace E Kissling
    [Show abstract] [Hide abstract] ABSTRACT: Purpose: Institutional conflicts of interest (ICOIs) occur when the institution or leaders with authority to act on behalf of the institution have conflicts of interest (COIs) that may threaten the objectivity, integrity, or trustworthiness of research because they could impact institutional decision making. The purpose of this study was to gather and analyze information about the ICOI policies of the top 100 U.S. academic research institutions, ranked according to total research funding. Method: From May-June 2014, the authors attempted to obtain ICOI policy information for the top 100 U.S. academic research institutions from publicly available Web sites or via e-mail inquiry. If an ICOI policy was not found, the institutions' online COI policies were examined. Data on each institution's total research funding, national funding rank, public versus private status, and involvement in clinical research were collected. The authors developed a coding system for categorizing the ICOI policies and used it to code the policies for nine items. Interrater agreement and P values were assessed. Results: Only 28/100 (28.0%) institutions had an ICOI policy. ICOI policies varied among the 28 institutions. Having an ICOI policy was positively associated with total research funding and national funding ranking but not with public versus private status or involvement in clinical research. Conclusions: Although most U.S. medical schools have policies that address ICOIs, most of the top academic research institutions do not. Federal regulation and guidance may be necessary to encourage institutions to adopt ICOI policies and establish a standard form of ICOI review.
    Full-text Article · Nov 2015 · Academic medicine: journal of the Association of American Medical Colleges
  • [Show abstract] [Hide abstract] ABSTRACT: o-Nitroanisole is an intermediate in the manufacture of azo dyes. In a National Toxicology Program stop-exposure study, o-nitroanisole induced hyperplasia, papillomas, and papillary carcinomas in the urinary bladder of Fischer 344/N rats. o-Nitroanisole was investigated since occupational or environmental exposure to aniline and azo dyes is a risk factor for urinary bladder cancer in humans. The current study describes the morphology of urinary bladder neoplasms seen in rats with respect to those observed in humans. This study also evaluated immunohistochemical expression of the cell cycle-related proteins cyclin D1 and p53 and the differentiation markers cytokeratin 20 and uroplakin III in hyperplastic (n = 11) and neoplastic (n = 6 papillomas, n = 11 carcinomas) lesions of the urinary bladder epithelium from rats treated with o-nitroanisole and in normal (n = 6) urinary bladders from untreated rats. The tumors observed were more similar to the papillary type rather than the muscle-invasive type of urinary bladder cancer in humans. The preneoplastic and neoplastic lesions observed suggest progression from hyperplasia to papilloma to papillary carcinoma. With neoplastic progression (hyperplasia to papilloma to carcinoma), cyclin D1 immunoreactivity progressively increased in intensity, percentage of cells staining, and distribution. Overexpression of p53 was not found. Cytokeratin 20 staining decreased in superficial cells, while uroplakin III staining increased in intermediate and basal cells with progression from hyperplasia to carcinoma. The results are consistent with increased cell cycle dysregulation or proliferation (cyclin D1), decreased differentiation (cytokeratin 20), and abnormal differentiation (uroplakin III) as lesions progress toward malignancy. © The Author(s) 2015.
    Article · Aug 2015 · Veterinary Pathology
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    [Show abstract] [Hide abstract] ABSTRACT: Bisphenol A (BPA) is a high production volume chemical associated with a wide range of health outcomes in animal and human studies. BPA is used as a developer in thermal paper products including cash register receipt paper; however little is known about exposure of cashiers to BPA and alternative compounds in receipt paper. To determine if handling receipt paper results in measurable absorption of BPA or the BPA alternatives, bisphenol S (BPS) and 4-hydroxyphenyl 4-isoprooxyphenylsulfone (BPSIP). Cashiers (n = 77) and non-cashiers (n=25) were recruited from the Raleigh-Durham-Chapel Hill region of North Carolina during 2011-2013. Receipts were analysed for the presence of BPA or alternatives considered for use in thermal paper. In cashiers, total urine and serum BPA, BPS, and BPSIP levels in post-shift samples (collected ≤ 2h after completing a shift) were compared with pre-shift samples (collected ≥ 24 hours after a work shift). Urine levels in cashiers were compared to levels from non-cashiers. Each receipt contained 1-2% by weight of the paper of BPA, BPS, or BPSIP. The post-shift geometric mean total urinary BPS concentration was significantly higher than the pre-shift mean in 33 cashiers who handled receipts containing BPS. Mean urine BPA concentrations in 31 cashiers who handled BPA receipts were as likely to decrease as increase after a shift, but the mean post-shift concentration was significantly higher than in non-cashiers. BPSIP was detected more frequently in urine of cashiers handling BPSIP receipts compared to non-cashiers. Only a few cashiers had detectable levels of total BPA or BPS in serum, whereas BPSIP tended to be detected more frequently. Thermal receipt paper is a potential source of occupational exposure to BPA, BPS, and BPSIP.
    Full-text Article · Aug 2015 · Environmental Health Perspectives
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    [Show abstract] [Hide abstract] ABSTRACT: Mice exposed to high levels of arsenic in utero are more susceptible to tumors such as hepatic and pulmonary carcinoma when they reach adulthood. However, effects of in utero arsenic exposure on general physiological functions such as reproduction and metabolism remain unclear. We evaluated the effect of in utero exposure to inorganic arsenic at the EPA drinking water standard (10 ppb) and tumor-inducing level (42.5 ppm) on reproductive end points and metabolic parameters when the exposed females reach adulthood. Pregnant CD-1 mice were exposed to sodium arsenite (0, 10 ppb, or 42.5 ppm) in drinking water from gestational day 10 to birth, the window of organ formation. At birth, exposed offspring were fostered to unexposed dams. We examined reproductive end points (age at vaginal opening, reproductive hormone levels, estrous cyclicity, and fertility) and metabolic parameters (body weight changes, hormone levels, body fat content, and glucose tolerance) of the exposed females in adulthood. Arsenic-exposed females (10 ppb and 42.5 ppm) exhibited early onset of vaginal opening. Fertility was not affected when females were exposed to the 10 ppb dose. However, the number of litters per female was decreased in females exposed to 42.5 ppm of arsenic in utero. In both 10 ppb and 42.5 ppm groups, exposed females had significantly higher body weight gain, body fat content, and glucose intolerance. Our findings reveal unexpected effects that in utero exposure to arsenic at a human relevant low dose and a tumor-inducing level leads to early onset of vaginal opening and obesity in female CD-1 mice.
    Full-text Article · Aug 2015 · Environmental Health Perspectives
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    David B Resnik · Elizabeth Wager · Grace E Kissling
    [Show abstract] [Hide abstract] ABSTRACT: This study gathered information about the retraction policies of the top 200 scientific journals, ranked by impact factor. Editors of the top 200 science journals for the year 2012 were contacted by email. One hundred forty-seven journals (74%) responded to a request for information. Of these, 95 (65%) had a retraction policy. Of journals with a retraction policy, 94% had a policy that allows the editors to retract articles without authors' consent. The majority of journals in this sample had a retraction policy, and almost all of them would retract an article without the authors' permission.
    Full-text Article · Jul 2015 · Journal of the Medical Library Association JMLA
  • [Show abstract] [Hide abstract] ABSTRACT: Human exposures to bisphenol A (BPA) are widespread. The current study addresses uncertainties regarding human pharmacokinetics of BPA. To reduce uncertainties about the metabolism and excretion of BPA in humans following oral administration. We exposed six men and eight women to 100μg/kg bw of deuterated BPA (d6-BPA) by oral administration and conducted blood and urine analysis over a three day period. The use of d6-BPA allowed administered d6-BPA to be distinguished from background native (unlabeled) BPA. We calculated the rate of oral absorption, serum elimination, half-life, area under the curve (AUC), urinary excretion, and metabolism to glucuronide and sulfate conjugates. Mean serum total (unconjugated and conjugated) d6-BPA Cmax of 1711nM (390ng/ml) was observed at Tmax of 1.1±0.50h. Unconjugated d6-BPA appeared in serum within 5-20min of dosing with a mean Cmax of 6.5nM (1.5ng/ml) observed at Tmax of 1.3±0.52h. Detectable blood levels of unconjugated or total d6-BPA were observed at 48h in some subjects at concentrations near the LOD (0.001-0.002ng/ml). The half-times for terminal elimination of total d6-BPA and unconjugated d6-BPA were 6.4±2.0h and 6.2±2.6h, respectively. Recovery of total administered d6-BPA in urine was 84-109%. Most subjects (10 of 14) excreted >90% as metabolites within 24h. Using more sensitive methods, our study expands the findings of other human oral pharmacokinetic studies. Conjugation reactions are rapid and nearly complete with unconjugated BPA comprising less than 1% of the total d6-BPA in blood at all times. Elimination of conjugates into urine largely occurs within 24h. Published by Elsevier Ltd.
    Article · Jun 2015 · Environment international
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    [Show abstract] [Hide abstract] ABSTRACT: Rodent lung tumors are morphologically similar to a subtype of human lung adenocarcinomas. The objective of this study was to evaluate Kirsten rat sarcoma oncogene homolog (Kras), epidermal growth factor receptor (Egfr), and tumor protein 53 (Tp53) mutations, which are relevant to human lung cancer, in cobalt metal dust (CMD)-induced alveolar/bronchiolar tumors of B6C3F1/N mice and F344/NTac rats. Kras mutations were detected in 67% (mice) and 31% (rats) of CMD-induced lung tumors and were predominantly exon 1 codon 12 G to T transversions (80% in mice and 57% in rats). Egfr mutations were detected in 17% (both mice and rats) of CMD-induced lung tumors and were predominantly in exon 20 with 50% G to A transitions (mice and rats). Tp53 mutations were detected in 19% (mice) and 23% (rats) of CMD-induced lung tumors and were predominant in exon 5 (mice, 69% transversions) and exon 6 (rats, all transitions). No mutations were observed for these genes in spontaneous lung tumors or normal lungs from untreated controls. Ames assay indicated that CMD is mutagenic in the absence but not in the presence of S9 mix. Thus, the mutation data (G to T transversions) and Ames assay results suggest that oxidative damage to DNA may be a contributing factor in CMD-induced pulmonary carcinogenesis in rodents. © 2015 by The Author(s).
    Full-text Article · Jun 2015 · Toxicologic Pathology

Publication Stats

3k Citations

Institutions

  • 2015
    • National Institutes of Health
      Maryland, United States
  • 2008
    • George Washington University
      Washington, Washington, D.C., United States
  • 2005
    • National Institute of Environmental Health Sciences
      • Cellular & Molecular Pathology Branch
      Durham, North Carolina, United States