Publications by authors named "James D Yager"

51 Publications

Age-Specific Serum Total and Free Estradiol Concentrations in Healthy Men in US Nationally Representative Samples.

J Endocr Soc 2019 Oct 19;3(10):1825-1836. Epub 2019 Jul 19.

Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.

Purpose: To report age-specific serum estradiol concentration in nonsmoking, lean US men without comorbidities. We provide concentrations from 30 and 15 to 20 years ago given previously described declines in serum estradiol in US men over time.

Methods: We used data from the Third National Health and Nutrition Examination Survey (NHANES III; 1988 to 1991) and continuous NHANES (1999 to 2004). Serum estradiol and SHBG were previously measured by competitive electrochemiluminescence immunoassays. Free estradiol was estimated from estradiol, SHBG, and albumin. By age, we calculated median concentrations overall and for nonsmoking, lean (body mass index <25 kg/m and waist <102 cm) men without diabetes, cardiovascular disease, or cancer.

Results: Overall, respective total estradiol medians for men ages 20 to 39, 40 to 59, and ≥60 years old were 37.0, 33.9, and 33.5 pg/mL in NHANES III and 31.3, 30.5, and 27.0 pg/mL in continuous NHANES. In nonsmoking, lean men without comorbidities, respective total estradiol medians were 32.0, 32.1, and 32.0 pg/mL in NHANES III and 29.1, 22.7, and 26.1 pg/mL in continuous NHANES. Overall, respective free estradiol medians were 0.82, 0.72, and 0.64 pg/mL in NHANES III and 0.67, 0.61, and 0.47 pg/mL in continuous NHANES. In nonsmoking, lean men without comorbidities, respective free estradiol medians were 0.64, 0.67, and 0.62 pg/mL in NHANES III and 0.58, 0.42, and 0.40 pg/mL continuous NHANES.

Conclusion: We report US nationally representative serum estradiol concentrations in healthy men, which could be used for targeting estradiol during testosterone supplementation and for general good health.
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http://dx.doi.org/10.1210/js.2019-00178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6749840PMC
October 2019

Estrogen down regulates COMT transcription via promoter DNA methylation in human breast cancer cells.

Toxicol Appl Pharmacol 2019 03 23;367:12-22. Epub 2019 Jan 23.

Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States. Electronic address:

Catechol-O-methyltransferase (COMT) acts as a 'gate-keeper' to prevent DNA damage during estrogen metabolism. Both experimental and epidemiological studies suggest the role of COMT in pathogenesis of human breast cancer (BCa). It was previously reported that inhibition of COMT enzyme activity in estradiol-treated human breast epithelial carcinoma-derived MCF-7 cells caused increased oxidative DNA damage and formation of mutagenic depurinating adducts. To improve our understanding of factors influencing estrogen metabolism in BCa, it requires a mechanistic study illustrating the regulation of this 'gate-keeper'. We investigated the epigenetic mechanisms underlying decreased COMT transcription in MCF-7 cells exposed to 17ß-estradiol (E2) and the phytoestrogen, genistein (GEN). CpG site-specific methylation at promoters for both soluble (S) and membrane-bound (MB) COMT transcripts were assessed. Both E2 and GEN induced CpG site-specific methylation within the distal promoter of MB-COMT. In addition, ChIP analysis showed that there was increased binding of DNMT3B, MBD2 and HDAC1 within this promoter. These epigenetic changes were associated with decreased COMT transcript levels. Interestingly, sulforaphane, an antioxidant commonly found in cruciferous vegetables, was able to reverse the estrogen-induced epigenetic changes and gene silencing of COMT. Our data provide a new insight in epigenetically targeting COMT transcription. Since reactive estrogen metabolites may contribute to breast cancer, our findings may help in developing prevention and/or intervention strategies for human BCa.
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http://dx.doi.org/10.1016/j.taap.2019.01.016DOI Listing
March 2019

Selenium and Sex Steroid Hormones in a U.S. Nationally Representative Sample of Men: A Role for the Link between Selenium and Estradiol in Prostate Carcinogenesis?

Cancer Epidemiol Biomarkers Prev 2019 03 27;28(3):578-583. Epub 2018 Nov 27.

Department of Chronic Disease Epidemiology, Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland.

Background: Given the recent findings from pooled studies about a potential inverse association between selenium levels and prostate cancer risk, this cross-sectional study aimed to investigate the association between serum selenium and serum concentrations of sex steroid hormones including estradiol in a nationally representative sample of U.S. men to investigate one mechanism by which selenium may influence prostate cancer risk.

Methods: The study included 1,420 men ages 20 years or older who participated in the Third National Health and Nutrition Examination Survey between 1988 and 1994. We calculated age/race-ethnicity-adjusted and multivariable-adjusted geometric mean serum concentrations of total and estimated free testosterone and estradiol, androstanediol glucuronide, and sex hormone binding globulin, and compared them across quartiles of serum selenium.

Results: Adjusting for age, race/ethnicity, smoking status, serum cotinine, household income, physical activity, alcohol consumption, and percent body fat, mean total estradiol [e.g., Q1, 38.00 pg/mL (95% confidence interval (CI), 36.03-40.08) vs. Q4, 35.29 pg/mL (95% CI, 33.53-37.14); = 0.050] and free estradiol [e.g., Q1, 0.96 pg/mL (95% CI, 0.92-1.01) vs. Q4, 0.90 (95% CI, 0.85-0.95); = 0.065] concentrations decreased over quartiles of selenium. Stratification by smoking and alcohol consumption, showed that the latter observation was stronger for never smokers ( = 0.073) and those with limited alcohol intake ( = 0.017). No associations were observed for the other sex steroid hormones studied.

Conclusions: Our findings suggests that a possible mechanism by which selenium may be protective for prostate cancer is related to estrogen.

Impact: Further studies of longitudinal measurements of serum and toenail selenium in relation to serum measurements of sex steroid hormones are needed.
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http://dx.doi.org/10.1158/1055-9965.EPI-18-0520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6401291PMC
March 2019

Plasma proteome correlates of lipid and lipoprotein: biomarkers of metabolic diversity and inflammation in children of rural Nepal.

J Lipid Res 2019 01 25;60(1):149-160. Epub 2018 Nov 25.

Center for Human Nutrition Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.

Proteins involved in lipoprotein metabolism can modulate cardiovascular health. While often measured to assess adult metabolic diseases, little is known about the proteomes of lipoproteins and their relation to metabolic dysregulation and underlying inflammation in undernourished child populations. The objective of this population study was to globally characterize plasma proteins systemically associated with HDL, LDL, and triglycerides in 500 Nepalese children. Abnormal lipid profiles characterized by elevated plasma triglycerides and low HDL-cholesterol (HDL-C) concentrations were common, especially in children with subclinical inflammation. Among 982 proteins analyzed, the relative abundance of 11, 12, and 52 plasma proteins was correlated with LDL-cholesterol ( = -0.43∼0.70), triglycerides ( = -0.39∼0.53), and HDL-C ( = -0.49∼0.79) concentrations, respectively. These proteins included apolipoproteins and numerous unexpected intracellular and extracellular matrix binding proteins, likely originating in hepatic and peripheral tissues. Relative abundance of two-thirds of the HDL proteome varied with inflammation, with acute phase reactants higher by 4∼40%, and proteins involved in HDL biosynthesis, cholesterol efflux, vitamin transport, angiogenesis, and tissue repair lower by 3∼20%. Untargeted plasma proteomics detects comprehensive sets of both known and novel lipoprotein-associated proteins likely reflecting systemic regulation of lipoprotein metabolism and vascular homeostasis. Inflammation-altered distributions of the HDL proteome may be predisposing undernourished populations to early chronic disease.
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http://dx.doi.org/10.1194/jlr.P088542DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6314253PMC
January 2019

Novel Plasma Proteins in Nepalese School-aged Children are Associated with a Small Head Size at Birth.

Sci Rep 2018 04 23;8(1):6390. Epub 2018 Apr 23.

Center for Human Nutrition, Dept. of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA.

Fetal growth restriction increases the risk of poor childhood growth and development and chronic disease in adulthood. Yet, little is known about biological pathways that mediate the long-lasting effects of suboptimal intrauterine growth. We explored the plasma proteome in a cohort of 500 Nepalese children 6-8 years of age to identify plasma proteins associated with multiple anthropometric size indicators at birth. Among 982 proteins analyzed, no proteins differed by birth weight, length, or weight-for-length indicators. However, 25 proteins were differentially abundant in children with a small vs normal head circumference at birth (<-2 vs. ≥-2 z-scores of the WHO growth standards). Angiopoietin-like 6 was 19.4% more abundant and the other 24 proteins were 7-21% less abundant in children with a small vs normal head circumference at birth, adjusted for potential confounders. The less abundant proteins included actins, actin filament organizing proteins (α-actinin, talin, filamin, cofilin, profilin, and vinculin), proteins involved in muscle contraction, and glycolytic enzymes, which were all positively correlated with each other. A novel cluster of childhood plasma proteins involved in angiogenesis and cytoskeleton dynamics was associated with a small head size at birth. The prognostic value of an altered proteomic phenotype remains to be investigated.
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http://dx.doi.org/10.1038/s41598-018-24640-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913316PMC
April 2018

Advancing the Certified in Public Health Examination: A Job Task Analysis.

Public Health Rep 2017 Jul/Aug;132(4):518-523. Epub 2017 Jun 22.

6 Center for Education Testing and Evaluation, University of Kansas, Kansas City, KS, USA.

Objectives: In 2014, the National Board of Public Health Examiners performed a job task analysis (JTA) to revise the Certified in Public Health (CPH) examination. The objectives of this study were to describe the development, administration, and results of the JTA survey; to present an analysis of the survey results; and to review the implications of this first-ever public health JTA.

Methods: An advisory committee of public health professionals developed a list of 200 public health job tasks categorized into 10 work domains. The list of tasks was incorporated into a web-based survey, and a snowball sample of public health professionals provided 4850 usable responses. Respondents rated job tasks as essential (4), very important (3), important (2), not very important (1), and never performed (0).

Results: The mean task importance ratings ranged from 2.61 to 3.01 (important to very important). The highest mean ratings were for tasks in the ethics domain (mean rating, 3.01). Respondents ranked 10 of the 200 tasks as the most important, with mean task rankings ranging from 2.98 to 3.39. We found subtle differences between male and female respondents and between master of public health and doctor of public health respondents in their rankings.

Conclusion: The JTA established a set of job tasks in 10 public health work domains, and the results provided a foundation for refining the CPH examination. Additional steps are needed to further modify the content outline of the examination. An empirical assessment of public health job tasks, using methods such as principal components analysis, may provide additional insight.
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http://dx.doi.org/10.1177/0033354917710015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507425PMC
July 2017

The Plasma Proteome Is Associated with Anthropometric Status of Undernourished Nepalese School-Aged Children.

J Nutr 2017 03 1;147(3):304-313. Epub 2017 Feb 1.

Center for Human Nutrition, Department of International Health, and.

Malnutrition affects body growth, size, and composition of children. Yet, few functional biomarkers are known to be associated with childhood morphology. This cross-sectional study examined associations of anthropometric indicators of height, musculature, and fat mass with plasma proteins by using proteomics in a population cohort of school-aged Nepalese children. Height, weight, midupper arm circumference (MUAC), triceps and subscapular skinfolds, upper arm muscle area (AMA), and arm fat area (AFA) were assessed in 500 children 6-8 y of age. Height-for-age scores (HAZs), weight-for-age scores (WAZs), and body mass index-for-age scores (BAZs) were derived from the WHO growth reference. Relative protein abundance was quantified by using tandem mass spectrometry. Protein-anthropometry associations were evaluated by linear mixed-effects models and identified as having a false discovery rate () <5%. Among 982 proteins, 1, 10, 14, and 17 proteins were associated with BAZ, HAZ, MUAC, and AMA, respectively ( < 0.05). Insulin-like growth factor (IGF)-I, 2 IGF-binding proteins, and carnosinase-1 were associated with both HAZ and AMA. Proteins involved in nutrient transport, activation of innate immunity, and bone mineralization were associated with HAZ. Several extracellular matrix proteins were positively associated with AMA alone. The proteomes of MUAC and AMA substantially overlapped, whereas no proteins were associated with AFA or triceps and subscapular skinfolds. Myosin light-chain kinase, possibly reflecting leakage from muscle, was inversely associated with BAZ. The proteome of WAZ was the largest ( = 33) and most comprehensive, including proteins involved in neural development and oxidative stress response, among others. Plasma proteomics confirmed known biomarkers of childhood growth and revealed novel proteins associated with lean mass in chronically undernourished children. Identified proteins may serve as candidates for assessing growth and nutritional status of children in similar undernourished settings. The antenatal micronutrient supplementation trial yielding the study cohort of children was registered at clinicaltrials.gov as NCT00115271.
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http://dx.doi.org/10.3945/jn.116.243014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5320403PMC
March 2017

Ethnic Variations in Estrogen and Its Metabolites: Sufficient to Explain Differences in Breast Cancer Incidence Rates?

J Natl Cancer Inst 2016 10;108(10)

Departments of Epidemiology (KV) and Environmental Science (JY), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD (KV, JY) Department of Epidemiology (KV) and Department of Environmental Science (JY).

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http://dx.doi.org/10.1093/jnci/djw223DOI Listing
October 2016

Information-dependent enrichment analysis reveals time-dependent transcriptional regulation of the estrogen pathway of toxicity.

Arch Toxicol 2017 Apr 3;91(4):1749-1762. Epub 2016 Sep 3.

The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.

The twenty-first century vision for toxicology involves a transition away from high-dose animal studies to in vitro and computational models (NRC in Toxicity testing in the 21st century: a vision and a strategy, The National Academies Press, Washington, DC, 2007). This transition requires mapping pathways of toxicity by understanding how in vitro systems respond to chemical perturbation. Uncovering transcription factors/signaling networks responsible for gene expression patterns is essential for defining pathways of toxicity, and ultimately, for determining the chemical modes of action through which a toxicant acts. Traditionally, transcription factor identification is achieved via chromatin immunoprecipitation studies and summarized by calculating which transcription factors are statistically associated with up- and downregulated genes. These lists are commonly determined via statistical or fold-change cutoffs, a procedure that is sensitive to statistical power and may not be as useful for determining transcription factor associations. To move away from an arbitrary statistical or fold-change-based cutoff, we developed, in the context of the Mapping the Human Toxome project, an enrichment paradigm called information-dependent enrichment analysis (IDEA) to guide identification of the transcription factor network. We used a test case of activation in MCF-7 cells by 17β estradiol (E2). Using this new approach, we established a time course for transcriptional and functional responses to E2. ERα and ERβ were associated with short-term transcriptional changes in response to E2. Sustained exposure led to recruitment of additional transcription factors and alteration of cell cycle machinery. TFAP2C and SOX2 were the transcription factors most highly correlated with dose. E2F7, E2F1, and Foxm1, which are involved in cell proliferation, were enriched only at 24 h. IDEA should be useful for identifying candidate pathways of toxicity. IDEA outperforms gene set enrichment analysis (GSEA) and provides similar results to weighted gene correlation network analysis, a platform that helps to identify genes not annotated to pathways.
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http://dx.doi.org/10.1007/s00204-016-1824-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5364265PMC
April 2017

Genetic variability in a frozen batch of MCF-7 cells invisible in routine authentication affecting cell function.

Sci Rep 2016 07 26;6:28994. Epub 2016 Jul 26.

Center for Alternatives to Animal Testing (CAAT), Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University Baltimore, MD, USA.

Common recommendations for cell line authentication, annotation and quality control fall short addressing genetic heterogeneity. Within the Human Toxome Project, we demonstrate that there can be marked cellular and phenotypic heterogeneity in a single batch of the human breast adenocarcinoma cell line MCF-7 obtained directly from a cell bank that are invisible with the usual cell authentication by short tandem repeat (STR) markers. STR profiling just fulfills the purpose of authentication testing, which is to detect significant cross-contamination and cell line misidentification. Heterogeneity needs to be examined using additional methods. This heterogeneity can have serious consequences for reproducibility of experiments as shown by morphology, estrogenic growth dose-response, whole genome gene expression and untargeted mass-spectroscopy metabolomics for MCF-7 cells. Using Comparative Genomic Hybridization (CGH), differences were traced back to genetic heterogeneity already in the cells from the original frozen vials from the same ATCC lot, however, STR markers did not differ from ATCC reference for any sample. These findings underscore the need for additional quality assurance in Good Cell Culture Practice and cell characterization, especially using other methods such as CGH to reveal possible genomic heterogeneity and genetic drifts within cell lines.
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http://dx.doi.org/10.1038/srep28994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4960662PMC
July 2016

Ethnic Variations in Estrogen and Its Metabolites: Sufficient to Explain Differences in Breast Cancer Incidence Rates?

J Natl Cancer Inst 2016 11 5;108(11). Epub 2016 Jul 5.

Departments of Epidemiology (KV) and Environmental Science (JY), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD (KV, JY) Department of Epidemiology (KV) and Department of Environmental Science (JY).

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http://dx.doi.org/10.1093/jnci/djw147DOI Listing
November 2016

Plasma Selenium Protein P Isoform 1 (SEPP1): A Predictor of Selenium Status in Nepalese Children Detected by Plasma Proteomics.

Int J Vitam Nutr Res 2017 Sep 10;87(5-6):1-10. Epub 2016 May 10.

1 Center for Human Nutrition, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.

Selenium deficiency or excess may have public health consequences, yet selenium status is infrequently characterized in populations, perhaps due to challenges in methodology. We are seeking to identify plasma proteins, using proteomics discovery and validation approaches, to serve as proxies for micronutrient status, including selenium, which may in the future be more readily assessed by robust, affordable field methods. In a sample of rural Nepalese children 6 - 8 years old (n = 500), the prevalence of selenium deficiency was 13.6 and 60.9 % at plasma selenium concentrations < 0.60 and < 0.89 µmol/L, respectively, assessed by atomic absorption spectroscopy. Relative abundance of selenoprotein P isoform 1 (SEPP1), glutathione reductase-3, and apolipoprotein A2 from discovery-based experiments was correlated with plasma selenium with a false discovery rate < 10 % (i. e., q < 0.10), all with p < 0.001. In linear mixed effects regression models to predict plasma selenium, only SEPP1 was significant (R = 0.63), estimating 8.2 % (95 % CI: 3.9 - 12.6) and 65.5(61.4 - 69.7)% of the in-sample population as deficient at each respective cut-off. Targeted quantification of SEPP1 in a preliminary series of specimens (n = 19) as a validation of the discovery approach revealed a high correlation with plasma selenium (r = 0.757, p = 0.0002). Plasma proteomics can identify valid plasma protein indicators of micronutrient status, as shown with selenium, comprising a step toward making population assessment of selenium status in vulnerable groups more accessible.
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http://dx.doi.org/10.1024/0300-9831/a000256DOI Listing
September 2017

General intelligence is associated with subclinical inflammation in Nepalese children: A population-based plasma proteomics study.

Brain Behav Immun 2016 Aug 30;56:253-63. Epub 2016 Mar 30.

Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA. Electronic address:

Improving child cognition in impoverished countries is a public health priority. Yet, biological pathways and associated biomarkers of impaired cognition remain poorly understood and largely unknown, respectively. This study aimed to explore and quantify associations between functional plasma protein biomarkers and childhood intellectual test performance. We applied proteomics to quantify proteins in plasma samples of 249 rural Nepalese children, 6-8years of age who, 1year later at 7-9years of age, were administered the Universal Nonverbal Intelligence Test (UNIT). Among 751 plasma proteins quantified, 22 were associated with UNIT scores, passing a false discovery rate threshold of 5.0% (q<0.05). UNIT scores were higher by 2.3-9.2 points for every 50% increase in relative abundance of two insulin-like growth factor binding proteins (IGFBPs), six subclasses of apolipoprotein (Apo) and transthyretin, and lower by 4.0-15.3 points for each 50% increase in relative abundance of 13 proteins predominantly involved in inflammation. Among them, IGFBP-acid labile subunit, orosomucoid 1 (ORM1), Apo C-I, and pyruvate kinase isoenzymes M1/M2 jointly explained 37% of the variance in UNIT scores. After additional adjustment for height-for-age Z-score and household socio-economic status as indicators of long-term nutritional and social stress, associations with 6 proteins involved in inflammation, including ORM1, α-1-antichymotrypsin, reticulocalbin 1, and 3 components of the complement cascade, remained significant (q<0.05). Using untargeted proteomics, stable, constitutive facets of subclinical inflammation were associated with lower developmental test performance in this rural South Asian child population. Plasma proteomics may offer opportunities to identify functional, antecedent biomarkers of child cognitive development.
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http://dx.doi.org/10.1016/j.bbi.2016.03.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4929134PMC
August 2016

Metabolomic network analysis of estrogen-stimulated MCF-7 cells: a comparison of overrepresentation analysis, quantitative enrichment analysis and pathway analysis versus metabolite network analysis.

Arch Toxicol 2017 Jan 2;91(1):217-230. Epub 2016 Apr 2.

Department of Environmental Health Sciences, Center for Alternatives to Animal Testing, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.

In the context of the Human Toxome project, mass spectroscopy-based metabolomics characterization of estrogen-stimulated MCF-7 cells was studied in order to support the untargeted deduction of pathways of toxicity. A targeted and untargeted approach using overrepresentation analysis (ORA), quantitative enrichment analysis (QEA) and pathway analysis (PA) and a metabolite network approach were compared. Any untargeted approach necessarily has some noise in the data owing to artifacts, outliers and misidentified metabolites. Depending on the chemical analytical choices (sample extraction, chromatography, instrument and settings, etc.), only a partial representation of all metabolites will be achieved, biased by both the analytical methods and the database used to identify the metabolites. Here, we show on the one hand that using a data analysis approach based exclusively on pathway annotations has the potential to miss much that is of interest and, in the case of misidentified metabolites, can produce perturbed pathways that are statistically significant yet uninformative for the biological sample at hand. On the other hand, a targeted approach, by narrowing its focus and minimizing (but not eliminating) misidentifications, renders the likelihood of a spurious pathway much smaller, but the limited number of metabolites also makes statistical significance harder to achieve. To avoid an analysis dependent on pathways, we built a de novo network using all metabolites that were different at 24 h with and without estrogen with a p value <0.01 (53) in the STITCH database, which links metabolites based on known reactions in the main metabolic network pathways but also based on experimental evidence and text mining. The resulting network contained a "connected component" of 43 metabolites and helped identify non-endogenous metabolites as well as pathways not visible by annotation-based approaches. Moreover, the most highly connected metabolites (energy metabolites such as pyruvate and alpha-ketoglutarate, as well as amino acids) showed only a modest change between proliferation with and without estrogen. Here, we demonstrate that estrogen has subtle but potentially phenotypically important alterations in the acyl-carnitine fatty acids, acetyl-putrescine and succinoadenosine, in addition to likely subtle changes in key energy metabolites that, however, could not be verified consistently given the technical limitations of this approach. Finally, we show that a network-based approach combined with text mining identifies pathways that would otherwise neither be considered statistically significant on their own nor be identified via ORA, QEA, or PA.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5047848PMC
http://dx.doi.org/10.1007/s00204-016-1695-xDOI Listing
January 2017

Biological Systems of Vitamin K: A Plasma Nutriproteomics Study of Subclinical Vitamin K Deficiency in 500 Nepalese Children.

OMICS 2016 Apr 25;20(4):214-23. Epub 2016 Feb 25.

1 Center for Human Nutrition, Departments of International Health, Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland.

Vitamin K (VK) is a fat-soluble vitamin whose deficiency disrupts coagulation and may disturb bone and cardiovascular health. However, the scale and systems affected by VK deficiency in pediatric populations remains unclear. We conducted a study of the plasma proteome of 500 Nepalese children 6-8 years of age (male/female ratio = 0.99) to identify proteins associated with VK status. We measured the concentrations of plasma lipids and protein induced by VK absence-II (PIVKA-II) and correlated relative abundance of proteins quantified by mass spectrometry with PIVKA-II. VK deficiency (PIVKA-II>2 μg/L) was associated with a higher abundance of low-density lipoproteins, total cholesterol, and triglyceride concentrations (p<0.01). Among 978 proteins observed in >10% of the children, five proteins were associated with PIVKA-II and seven proteins were differentially abundant between VK deficient versus sufficient children, including coagulation factor-II, hemoglobin, and vascular endothelial cadherin, passing a false discovery rate (FDR) threshold of 10% (q<0.10). Among 27 proteins associated with PIVKA-II or VK deficiency at a less stringent FDR (q<0.20), a network comprised of hemoglobin subunits and erythrocyte anti-oxidative enzymes were highly and positively correlated each other (all r>0.7). Untargeted proteomics offers a novel systems approach to elucidating biological processes of coagulation, vascularization, and erythrocyte oxidative stress related to VK status. The results may help elucidate subclinical metabolic disturbances related to VK deficiency in populations.
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http://dx.doi.org/10.1089/omi.2015.0178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4840917PMC
April 2016

Plasma Proteome Biomarkers of Inflammation in School Aged Children in Nepal.

PLoS One 2015 4;10(12):e0144279. Epub 2015 Dec 4.

Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.

Inflammation is a condition stemming from complex host defense and tissue repair mechanisms, often simply characterized by plasma levels of a single acute reactant. We attempted to identify candidate biomarkers of systemic inflammation within the plasma proteome. We applied quantitative proteomics using isobaric mass tags (iTRAQ) tandem mass spectrometry to quantify proteins in plasma of 500 Nepalese children 6-8 years of age. We evaluated those that co-vary with inflammation, indexed by α-1-acid glycoprotein (AGP), a conventional biomarker of inflammation in population studies. Among 982 proteins quantified in >10% of samples, 99 were strongly associated with AGP at a family-wise error rate of 0.1%. Magnitude and significance of association varied more among proteins positively (n = 41) than negatively associated (n = 58) with AGP. The former included known positive acute phase proteins including C-reactive protein, serum amyloid A, complement components, protease inhibitors, transport proteins with anti-oxidative activity, and numerous unexpected intracellular signaling molecules. Negatively associated proteins exhibited distinct differences in abundance between secretory hepatic proteins involved in transporting or binding lipids, micronutrients (vitamin A and calcium), growth factors and sex hormones, and proteins of largely extra-hepatic origin involved in the formation and metabolic regulation of extracellular matrix. With the same analytical approach and the significance threshold, seventy-two out of the 99 proteins were commonly associated with CRP, an established biomarker of inflammation, suggesting the validity of the identified proteins. Our findings have revealed a vast plasma proteome within a free-living population of children that comprise functional biomarkers of homeostatic and induced host defense, nutrient metabolism and tissue repair, representing a set of plasma proteins that may be used to assess dynamics and extent of inflammation for future clinical and public health application.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0144279PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4670104PMC
June 2016

A Plasma α-Tocopherome Can Be Identified from Proteins Associated with Vitamin E Status in School-Aged Children of Nepal.

J Nutr 2015 Dec 7;145(12):2646-56. Epub 2015 Oct 7.

Departments of International Health.

Background: The term vitamin E describes a family of 8 vitamers, 1 of which is α-tocopherol, that is essential for human health. Vitamin E status remains largely unknown in low-income countries because of the complexity and cost of measurement. Quantitative proteomics may offer an approach for identifying plasma proteins for assessing vitamin E status in these populations.

Objective: To improve options for vitamin E status assessment, we sought to detect and quantify a set of plasma proteins associated with α- and γ-tocopherol concentrations in a cohort of 500 rural Nepalese children aged 6-8 y and, based on nutrient-protein associations, to predict the prevalence of vitamin E deficiency (α-tocopherol <12 μmol/L).

Methods: Study children were born to mothers enrolled in an earlier antenatal micronutrient trial in Sarlahi District, Nepal. Plasma α- and γ-tocopherol concentrations were measured by high-performance liquid chromatography. Plasma aliquots were depleted of 6 high-abundance proteins, digested with trypsin, labeled with isobaric mass tags, and assessed for relative protein abundance by tandem mass spectrometry. Linear mixed-effects models were used to evaluate the association between α-tocopherol status and relative protein abundance and to predict deficiency.

Results: We quantified 982 plasma proteins in >10% of all child samples, of which 119 correlated with α-tocopherol (false discovery rate, q < 0.10). Proteins were primarily involved in lipid transport, coagulation, repair, innate host defenses, neural function, and homeostasis. Six proteins [apolipoprotein (apo)C-III; apoB; pyruvate kinase, muscle; forkhead box 04; unc5 homolog C; and regulator of G-protein signaling 8] explained 71% of the variability in plasma α-tocopherol, predicting an in-sample population prevalence of vitamin E deficiency of 51.4% (95% CI: 46.4%, 56.3%) compared with a measured prevalence of 54.8%. Plasma γ-tocopherol was associated with 12 proteins (q < 0.10), 2 of which (apoC-III and Misato 1) explained 20% of its variability.

Conclusions: In this undernourished population of children in South Asia, quantitative proteomics identified a large plasma α-tocopherome from which 6 proteins predicted the prevalence of vitamin E deficiency. The findings illustrate that protein biomarkers, once absolutely quantified, can potentially predict micronutrient deficiencies in populations. The maternal micronutrient supplementation trial from which data were derived as a follow-up activity was registered with clinicaltrials.gov as NCT00115271.
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http://dx.doi.org/10.3945/jn.115.210682DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6619677PMC
December 2015

The human toxome project.

ALTEX 2015 4;32(2):112-24. Epub 2015 Mar 4.

Johns Hopkins Bloomberg School of Public Health, Center for Alternatives to Animal Testing, Baltimore, MD, USA.

The Human Toxome Project, funded as an NIH Transformative Research grant 2011-2016, is focused on developing the concepts and the means for deducing, validating and sharing molecular pathways of toxicity (PoT). Using the test case of estrogenic endocrine disruption, the responses of MCF-7 human breast cancer cells are being phenotyped by transcriptomics and mass-spectroscopy-based metabolomics. The bioinformatics tools for PoT deduction represent a core deliverable. A number of challenges for quality and standardization of cell systems, omics technologies and bioinformatics are being addressed. In parallel, concepts for annotation, validation and sharing of PoT information, as well as their link to adverse outcomes, are being developed. A reasonably comprehensive public database of PoT, the Human Toxome Knowledge-base, could become a point of reference for toxicological research and regulatory test strategies.
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http://dx.doi.org/10.14573/altex.1502091DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4778566PMC
November 2015

Mechanisms of estrogen carcinogenesis: The role of E2/E1-quinone metabolites suggests new approaches to preventive intervention--A review.

Authors:
James D Yager

Steroids 2015 Jul 24;99(Pt A):56-60. Epub 2014 Aug 24.

Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Rm. 6527, Baltimore, MD 21205, United States. Electronic address:

Unlabelled: Studies in hamsters, mice and rats have demonstrated that estradiol (E2), its interconvertible metabolite estrone (E1) and their catechol metabolites, in particular 4-hydroxy E2/E1, are carcinogenic in the kidney, uterus and mammary gland. Observational studies and clinical trials consistently show that sustained exposure to E2/E1 is associated with the development of sporadic breast cancer. The weight of evidence supports the contribution of two complementary pathways in the initiation, promotion and progression of breast cancer. One pathway involves activation of nuclear and cytoplasmic signaling pathways through the binding of estrogen to nuclear and membrane-bound estrogen receptors leading to increased cell proliferation. The other pathway involves the oxidative metabolism of E2/E1 to catechols and then reactive quinones that can contribute to oxidative DNA damage and form specific, mutagenic depurinating adducts with adenine and guanine which then in turn can serve as biomarkers for the occurrence of these processes. Both pathways can serve as portals to preventive intervention. Antiestrogens are used clinically to block receptor-mediated signaling to block tumor growth. Various chemopreventive agents such as sulforaphane (SFN) and resveratrol have been shown in cell culture to block oxidative metabolism of E2/E1 and thus prevent DNA damage. Pretreatment of MCF-7 and MCF-10F cells with and inhibitor of catechol-O-methyltransferase (COMT) followed by treatment with E2 or 4-OH E2 caused increased oxidative DNA damage (8-oxo-dG) and depurinating DNA adducts showing the importance of E2-catechol O-methylation by COMT as a protective pathway. E2 treatment of MCF-10A cells with E2 or 4-OH E2 caused an increase in E2-adenine and guanine adducts. Treatment with sulforaphane increased

Nad(p)h: quinone oxidoreductase 1 (NQO1) and glutathione-S-transferase A1 (GSTA1) expression without affecting expression of catechol-O-methyltransferase (COMT) or cytochrome P450 1B1. Pretreatment with SFN decreased depurinating DNA adducts while increasing levels of 4-OCH3E1/2 and 4-OHE1/2-glutathione conjugates. Treatment of MCF-10F cells with E2 or 4-OH-E2 also caused increased depurinating DNA adducts and neoplastic transformation while pretreatment with resveratrol caused a reduction in adduct levels and neoplastic transformation. Increased levels of estrogen-quinone conjugates and DNA adducts have also been detected in urine of women at increased risk for and with breast cancer. These observations support the notion that targeting the estrogen/estrone metabolism pathway may be another way to reduce breast cancer risk.
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http://dx.doi.org/10.1016/j.steroids.2014.08.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4339663PMC
July 2015

Massive open online courses in public health.

Front Public Health 2013 25;1:59. Epub 2013 Nov 25.

Center for Teaching and Learning, Johns Hopkins Bloomberg School of Public Health , Baltimore, MD , USA ; Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health , Baltimore, MD , USA.

Massive open online courses (MOOCs) represent a new and potentially transformative model for providing educational opportunities to learners not enrolled in a formal educational program. The authors describe the experience of developing and offering eight MOOCs on a variety of public health topics. Existing institutional infrastructure and experience with both for-credit online education and open educational resources mitigated the institutional risk and resource requirements. Although learners are able to enroll easily and freely and do so in large numbers, there is considerable variety in the level of participation and engagement among enrollees. As a result, comprehensive and accurate assessment of meaningful learning progress remains a major challenge for evaluating the effectiveness of MOOCs for providing public health education.
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http://dx.doi.org/10.3389/fpubh.2013.00059DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3859968PMC
December 2013

The plasma proteome identifies expected and novel proteins correlated with micronutrient status in undernourished Nepalese children.

J Nutr 2013 Oct 21;143(10):1540-8. Epub 2013 Aug 21.

Mass Spectrometry and Proteomics Core Facility.

Micronutrient deficiencies are common in undernourished societies yet remain inadequately assessed due to the complexity and costs of existing assays. A plasma proteomics-based approach holds promise in quantifying multiple nutrient:protein associations that reflect biological function and nutritional status. To validate this concept, in plasma samples of a cohort of 500 6- to 8-y-old Nepalese children, we estimated cross-sectional correlations between vitamins A (retinol), D (25-hydroxyvitamin D), and E (α-tocopherol), copper, and selenium, measured by conventional assays, and relative abundance of their major plasma-bound proteins, measured by quantitative proteomics using 8-plex iTRAQ mass tags. The prevalence of low-to-deficient status was 8.8% (<0.70 μmol/L) for retinol, 19.2% (<50 nmol/L) for 25-hydroxyvitamin D, 17.6% (<9.3 μmol/L) for α-tocopherol, 0% (<10 μmol/L) for copper, and 13.6% (<0.6 μmol/L) for selenium. We identified 4705 proteins, 982 in >50 children. Employing a linear mixed effects model, we observed the following correlations: retinol:retinol-binding protein 4 (r = 0.88), 25-hydroxyvitamin D:vitamin D-binding protein (r = 0.58), α-tocopherol:apolipoprotein C-III (r = 0.64), copper:ceruloplasmin (r = 0.65), and selenium:selenoprotein P isoform 1 (r = 0.79) (all P < 0.0001), passing a false discovery rate threshold of 1% (based on P value-derived q values). Individual proteins explained 34-77% (R(2)) of variation in their respective nutrient concentration. Adding second proteins to models raised R(2) to 48-79%, demonstrating a potential to explain additional variation in nutrient concentration by this strategy. Plasma proteomics can identify and quantify protein biomarkers of micronutrient status in undernourished children. The maternal micronutrient supplementation trial, from which data were derived as a follow-up activity, was registered at clinicaltrials.gov as NCT00115271.
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http://dx.doi.org/10.3945/jn.113.175018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6879017PMC
October 2013

Reduced formation of depurinating estrogen-DNA adducts by sulforaphane or KEAP1 disruption in human mammary epithelial MCF-10A cells.

Carcinogenesis 2013 Nov 10;34(11):2587-92. Epub 2013 Jul 10.

Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.

Sulforaphane (SFN) is a potent inducer of detoxication enzymes such as NAD(P)H:quinone oxidoreductase 1 (NQO1) and glutathione-S-transferase (GST) via the Kelch-like erythroid-derived protein with CNC homology-associated protein 1 (Keap1)-NF-E2-related factor 2 (Nrf2) signaling pathway. NQO1 reduces the carcinogenic estrogen metabolite, catechol estrogen-3,4-quinone, whereas GSTs detoxify it through conjugation with glutathione. These 3,4-quinones can react with DNA to form depurinating DNA adducts. Thus, SFN may alter estrogen metabolism and thus protect against estrogen-mediated DNA damage and carcinogenesis. Human breast epithelial MCF-10A cells were treated with either vehicle or SFN and either estradiol (E2) or its metabolite 4-hydroxyestradiol (4-OHE2). 4-Hydroxy-derived estrogen metabolites and depurinating DNA adducts formed from E2 and its interconvertable metabolite estrone (E1) were analyzed by mass spectrometry. Levels of the depurinated adducts, 4-OHE1/2-1-N3Adenine and 4-OHE1/2-1-N7Guanine, were reduced by 60% in SFN-treated cells, whereas levels of 4-OCH3E1/2 and 4-OHE1/2-glutathione conjugates increased. To constitutively enhance the expression of Nrf2-regulated genes, cells were treated with either scrambled or siKEAP1 RNA. Following E2 or 4-OHE2 treatments, levels of the adenine and guanine adducts dropped 60-70% in siKEAP1-treated cells, whereas 4-OHE1/2-glutathione conjugates increased. However, 4-OCH3E1/2 decreased 50% after siKEAP1 treatment. Thus, treatment with SFN or siKEAP1 has similar effects on reduction of depurinating estrogen-DNA adduct levels following estrogen challenge. However, these pharmacologic and genetic approaches have different effects on estrogen metabolism to O-methyl and glutathione conjugates. Activation of the Nrf2 pathway, especially elevated NQO1, may account for some but not all of the protective effects of SFN against estrogen-mediated DNA damage.
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http://dx.doi.org/10.1093/carcin/bgt246DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888356PMC
November 2013

Catechol--methyltransferase: characteristics, polymorphisms and role in breast cancer.

Authors:
James D Yager

Drug Discov Today Dis Mech 2012 Jun;9(1-2):e41-e46

Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, United States.

Catechol estrogens are carcinogenic, probably because of their estrogenicity and potential for further oxidative metabolism to reactive quinones. Estrogenic quinones cause oxidative DNA damage as well as form mutagenic depurinating adenine and guanine adducts. -Methylation by catechol--methyltransferase (COMT) blocks their estrogenicity and prevents their oxidation to quinones. A single gene encodes both membrane bound (MB) and soluble (S) forms of COMT. The COMT gene contains 34 single nucleotide polymorphisms (SNPs). The valine108 (S-COMT)/158 (MB-COMT) SNP encodes a low activity form of COMT and has been widely studied as a putative risk factor for breast cancer, with inconsistent results. Investigations of two other SNPs in the promoter of MB-COMT that may affect its expression have also provided mixed results. Future studies on the role of COMT in breast cancer should incorporate measurement of biomarkers that reflect COMT activity and its protective effects.
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http://dx.doi.org/10.1016/j.ddmec.2012.10.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3665426PMC
June 2012

Statistical inference from multiple iTRAQ experiments without using common reference standards.

J Proteome Res 2013 Feb 16;12(2):594-604. Epub 2013 Jan 16.

Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.

Isobaric tags for relative and absolute quantitation (iTRAQ) is a prominent mass spectrometry technology for protein identification and quantification that is capable of analyzing multiple samples in a single experiment. Frequently, iTRAQ experiments are carried out using an aliquot from a pool of all samples, or "masterpool", in one of the channels as a reference sample standard to estimate protein relative abundances in the biological samples and to combine abundance estimates from multiple experiments. In this manuscript, we show that using a masterpool is counterproductive. We obtain more precise estimates of protein relative abundance by using the available biological data instead of the masterpool and do not need to occupy a channel that could otherwise be used for another biological sample. In addition, we introduce a simple statistical method to associate proteomic data from multiple iTRAQ experiments with a numeric response and show that this approach is more powerful than the conventionally employed masterpool-based approach. We illustrate our methods using data from four replicate iTRAQ experiments on aliquots of the same pool of plasma samples and from a 406-sample project designed to identify plasma proteins that covary with nutrient concentrations in chronically undernourished children from South Asia.
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http://dx.doi.org/10.1021/pr300624gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4223774PMC
February 2013

Estrogen receptor-dependent and independent mechanisms of breast cancer carcinogenesis.

Steroids 2013 Feb 20;78(2):161-70. Epub 2012 Nov 20.

University of Virginia, Department of Medicine, Division of Endocrinology & Metabolism, Charlottesville, VA 22908, United States.

Long term exposure to estrogens is associated with an increased risk of breast cancer. The precise mechanisms responsible for estrogen mediated carcinogenesis are not well understood. The most widely accepted theory holds that estradiol (E(2)), acting through estrogen receptor alpha (ERα), stimulates cell proliferation and initiates mutations arising from replicative errors occurring during pre-mitotic DNA synthesis. The promotional effects of E(2) then support the growth of cells harboring mutations. Over a period of time, sufficient numbers of mutations accumulate to induce neoplastic transformation. Laboratory and epidemiological data also suggest that non-receptor mediated mechanisms resulting from the genotoxic effects of estrogen metabolites are involved in breast cancer development. This manuscript critically reviews existing data implicating both ER-dependent and -independent mechanisms. The weight of evidence supports the possibility that both mechanisms are involved in the carcinogenic process. In addition, estrogen metabolites likely modulate stem cell functionality and cancer progression. The roles of ER dependent and independent actions in the carcinogenic process are pertinent to the consideration of breast cancer preventative agents as anti-estrogens block only receptor mediated pathways whereas the aromatase inhibitors block both.
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http://dx.doi.org/10.1016/j.steroids.2012.11.001DOI Listing
February 2013

The use of biomarkers of toxicity for integrating in vitro hazard estimates into risk assessment for humans.

ALTEX 2012 ;29(4):411-25

Institute for Risk Assessment Sciences, Division of Toxicology, Utrecht University, The Netherlands.

The role that in vitro systems can play in toxicological risk assessment is determined by the appropriateness of the chosen methods, with respect to the way in which in vitro data can be extrapolated to the in vivo situation. This report presents the results of a workshop aimed at better defining the use of in vitro-derived biomarkers of toxicity (BoT) and determining the place these data can have in human risk assessment. As a result, a conceptual framework is presented for the incorporation of in vitro-derived toxicity data into the risk assessment process. The selection of BoT takes into account that they need to distinguish adverse and adaptive changes in cells. The framework defines the place of in vitro systems in the context of data on exposure, structural and physico-chemical properties, and toxicodynamic and biokinetic modeling. It outlines the determination of a proper point-of-departure (PoD) for in vitro-in vivo extrapolation, allowing implementation in risk assessment procedures. A BoT will need to take into account both the dynamics and the kinetics of the compound in the in vitro systems. For the implementation of the proposed framework it will be necessary to collect and collate data from existing literature and new in vitro test systems, as well as to categorize biomarkers of toxicity and their relation to pathways-of-toxicity. Moreover, data selection and integration need to be driven by their usefulness in a quantitative in vitro-in vivo extrapolation (QIVIVE).
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http://dx.doi.org/10.14573/altex.2012.4.411DOI Listing
March 2013

Critical evaluation of the use of dogs in biomedical research and testing in Europe.

ALTEX 2011 ;28(4):326-40

Centre for Alternatives to Animal Testing, Europe, University of Konstanz, Germany.

Dogs are sometimes referred to as "man's best friend" and with the increase in urbanization and lifestyle changes, dogs are seen by their owners as family members. Society expresses specific concerns about the experimental use of dogs, as they are sometimes perceived to have a special status for humans. This may appear somewhat conflicting with the idea that the intrinsic value of all animals is the same, and that also several other animal species are used in biomedical research and toxicology. This aspect and many others are discussed in an introductory chapter dealing with ethical considerations on the use of dogs as laboratory animals. The report gives an overview on the use of dogs in biomedical research, safety assessment and the drug developmental process and reflects the discussion on the use of dogs as second (non-rodent)species in toxicity testing. Approximately 20,000 dogs are used in scientific procedures in Europe every year, and their distinct genetic, physiological and behavioral characteristics may support their use as models for e.g. behavioral analysis and genetic research. Advances in the 3Rs (Replacement, Reduction and Refinement of experiments using dogs) are described, potential opportunities are discussed and recommendations for further progress in this area are made.
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http://dx.doi.org/10.14573/altex.2011.4.326DOI Listing
April 2012

Manganese superoxide dismutase: effect of the ala16val polymorphism on protein, activity, and mRNA levels in human breast cancer cell lines and stably transfected mouse embryonic fibroblasts.

Mol Cell Biochem 2010 Feb 13;335(1-2):107-18. Epub 2009 Sep 13.

Division of Toxicology, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, USA.

The manganese superoxide dismutase (MnSOD) ala16val polymorphism has been associated with various diseases including breast cancer. In the present study, we investigated levels of MnSOD protein, enzymatic activity, and mRNA with respect to MnSOD genotype in several human breast carcinoma cell lines and in mouse embryonic fibroblasts (MEF), developed from the MnSOD knockout mouse, stably expressing human MnSOD-ala and MnSOD-val. In human breast cell lines, the MnSOD-ala allele was associated with increased levels of MnSOD protein and MnSOD protein per unit mRNA. In the MEF transformants, MnSOD activity correlated fairly well with MnSOD protein levels. MnSOD mRNA expression was significantly lower in MnSOD-ala versus MnSOD-val lines. MnSOD protein and activity levels were not related to MnSOD genotype in the transformed MEF, although, as observed in the human breast cell lines, the MEF human MnSOD-ala lines produced significantly more human MnSOD protein per unit mRNA than the human MnSOD-val lines. This suggests that there is more efficient production of MnSOD-ala protein compared to MnSOD-val protein. Examination of several indicators of reactive oxygen species levels, including superoxide and hydrogen peroxide, in wild-type MEF and in MEF expressing similar elevated amounts of MnSOD-ala or val activity did not show differences related to the levels of MnSOD protein expression. In conclusion, in both human breast carcinoma cell lines and MEF cell lines stably transfected with human MnSOD, the MnSOD-ala allele was associated with increased production of MnSOD protein per unit mRNA indicating a possible imbalance in MnSOD protein production from the MnSOD-val mRNA.
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http://dx.doi.org/10.1007/s11010-009-0247-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2809810PMC
February 2010

Public health studies as an undergraduate major.

Public Health Rep 2008 Nov-Dec;123(6):812-7

Zanvyl Krieger School of Arts and Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2556709PMC
http://dx.doi.org/10.1177/003335490812300620DOI Listing
September 2009