National Institute of Environmental Health science NIEHS

Alexander, NC, United States

National Institute of Environmental Health science NIEHS

Alexander, NC, United States
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Larriba Y.,University of Valladolid | Rueda C.,University of Valladolid | Fernandez M.A.,University of Valladolid | Peddada S.D.,National Institute of Environmental Health science NIEHS
Nucleic Acids Research | Year: 2016

Motivation: Many biological processes, such as cell cycle, circadian clock, menstrual cycles, are governed by oscillatory systems consisting of numerous components that exhibit rhythmic patterns over time. It is not always easy to identify such rhythmic components. For example, it is a challenging problem to identify circadian genes in a given tissue using time-course gene expression data. There is a great potential for misclassifying non-rhythmic as rhythmic genes and vice versa. This has been a problem of considerable interest in recent years. In this article we develop a constrained inference based methodology called Order Restricted Inference for Oscillatory Systems (ORIOS) to detect rhythmic signals. Instead of using mathematical functions (e.g. sinusoidal) to describe shape of rhythmic signals, ORIOS uses mathematical inequalities. Consequently, it is robust and not limited by the biologist's choice of the mathematical model. We studied the performance of ORIOS using simulated as well as real data obtained from mouse liver, pituitary gland and data from NIH3T3, U2OS cell lines. Our results suggest that, for a broad collection of patterns of gene expression, ORIOS has substantially higher power to detect true rhythmic genes in comparison to some popular methods, while also declaring substantially fewer non-rhythmic genes as rhythmic. Availability and Implementation: A user friendly code implemented in R language can be downloaded from http://www.niehs.nih.gov/ research/atniehs/labs/bb/staff/peddada/index.cfm.


Jackson J.P.,Life Technologies | Jackson J.P.,transporter | Li L.,University of Maryland, Baltimore | Chamberlain E.D.,Life Technologies | And 3 more authors.
Drug Metabolism and Disposition | Year: 2016

Over the last decade HepaRG cells have emerged as a promising alternative to primary human hepatocytes (PHH) and have been featured in over 300 research publications. Most of these reports employed freshly differentiated HepaRG cells that require time-consuming culture (∼28 days) for full differentiation. Recently, a cryopreserved, predifferentiated format of HepaRG cells (termed here "cryo-HepaRG") has emerged as a new model that improves global availability and experimental flexibility; however, it is largely unknown whether HepaRG cells in this format fully retain their hepatic characteristics. Therefore, we systematically investigated the hepatocyte functionality of cryo-HepaRG cultures in context with the range of interindividual variation observed with PHH in both sandwich-culture and suspension formats. These evaluations uncovered a novel adaptation period for the cryo-HepaRG format and demonstrated the impact of extracellular matrix on cryo-HepaRG functionality. Pharmacologically important drug-metabolizing alleles were genotyped in HepaRG cells and poor metabolizer alleles for CYP2D6, CYP2C9, and CYP3A5 were identified and consistent with higher frequency alleles found in individuals of Caucasian decent. We observed liver enzyme inducibility with aryl hydrocarbon receptor, constitutive androstane receptor (CAR), and pregnane X receptor activators comparable to that of sandwich-cultured PHH. Finally, we show for the first time that cryo-HepaRG supports proper CAR cytosolic sequestration and translocation to hepatocyte nuclei in response to phenobarbital treatment. Taken together, these data reveal important considerations for the use of this cell model and demonstrate that cryo-HepaRG are suitable for metabolism and toxicology screening. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.


Sharma N.K.,Dr D Y Patil Biotechnology And Bioinformatics Institute | Lebedeva M.,Yale University | Stumpf J.D.,National Institute of Environmental Health science NIEHS | Shadel G.S.,Yale University | Santos J.H.,National Institute of Environmental Health science NIEHS
DNA Repair | Year: 2014

Ataxia Telangiectasia (A-T) is a progressive childhood disorder characterized most notably by cerebellar degeneration and predisposition to cancer. A-T is caused by mutations in the kinase ATM, a master regulator of the DNA double-strand break response. In addition to DNA-damage signaling defects, A-T cells display mitochondrial dysfunction that is thought to contribute to A-T pathogenesis. However, the molecular mechanism leading to mitochondrial dysfunction in A-T remains unclear. Here, we show that lack of ATM leads to reduced mitochondrial DNA (mtDNA) integrity and mitochondrial dysfunction, which are associated to defective mtDNA repair. While protein levels of mtDNA repair proteins are essentially normal, in the absence of ATM levels specifically of DNA ligase III (Lig3), the only DNA ligase working in mitochondria is reduced. The reduction of Lig3 is observed in different A-T patient cells, in brain and pre-B cells derived from ATM knockout mice as well as upon transient or stable knockdown of ATM. Furthermore, pharmacological inhibition of Lig3 in wild type cells phenocopies the mtDNA repair defects observed in A-T patient cells. As targeted deletion of LIG3 in the central nervous system causes debilitating ataxia in mice, reduced Lig3 protein levels and the consequent mtDNA repair defect may contribute to A-T neurodegeneration. A-T is thus the first disease characterized by diminished Lig3. © 2013.


PubMed | National Institute of Environmental Health science NIEHS and Yale University
Type: | Journal: DNA repair | Year: 2013

Ataxia Telangiectasia (A-T) is a progressive childhood disorder characterized most notably by cerebellar degeneration and predisposition to cancer. A-T is caused by mutations in the kinase ATM, a master regulator of the DNA double-strand break response. In addition to DNA-damage signaling defects, A-T cells display mitochondrial dysfunction that is thought to contribute to A-T pathogenesis. However, the molecular mechanism leading to mitochondrial dysfunction in A-T remains unclear. Here, we show that lack of ATM leads to reduced mitochondrial DNA (mtDNA) integrity and mitochondrial dysfunction, which are associated to defective mtDNA repair. While protein levels of mtDNA repair proteins are essentially normal, in the absence of ATM levels specifically of DNA ligase III (Lig3), the only DNA ligase working in mitochondria is reduced. The reduction of Lig3 is observed in different A-T patient cells, in brain and pre-B cells derived from ATM knockout mice as well as upon transient or stable knockdown of ATM. Furthermore, pharmacological inhibition of Lig3 in wild type cells phenocopies the mtDNA repair defects observed in A-T patient cells. As targeted deletion of LIG3 in the central nervous system causes debilitating ataxia in mice, reduced Lig3 protein levels and the consequent mtDNA repair defect may contribute to A-T neurodegeneration. A-T is thus the first disease characterized by diminished Lig3.


PubMed | Karolinska Institutet, Danish Cancer Society, Finnish National Institute for Health and Welfare, International Agency for Research on Cancer IARC and 57 more.
Type: Journal Article | Journal: Human molecular genetics | Year: 2016

Candidate gene and genome-wide association studies (GWAS) have identified 15 independent genomic regions associated with bladder cancer risk. In search for additional susceptibility variants, we followed up on four promising single-nucleotide polymorphisms (SNPs) that had not achieved genome-wide significance in 6911 cases and 11 814 controls (rs6104690, rs4510656, rs5003154 and rs4907479, P < 1 10(-6)), using additional data from existing GWAS datasets and targeted genotyping for studies that did not have GWAS data. In a combined analysis, which included data on up to 15 058 cases and 286 270 controls, two SNPs achieved genome-wide statistical significance: rs6104690 in a gene desert at 20p12.2 (P = 2.19 10(-11)) and rs4907479 within the MCF2L gene at 13q34 (P = 3.3 10(-10)). Imputation and fine-mapping analyses were performed in these two regions for a subset of 5551 bladder cancer cases and 10 242 controls. Analyses at the 13q34 region suggest a single signal marked by rs4907479. In contrast, we detected two signals in the 20p12.2 region-the first signal is marked by rs6104690, and the second signal is marked by two moderately correlated SNPs (r(2) = 0.53), rs6108803 and the previously reported rs62185668. The second 20p12.2 signal is more strongly associated with the risk of muscle-invasive (T2-T4 stage) compared with non-muscle-invasive (Ta, T1 stage) bladder cancer (case-case P 0.02 for both rs62185668 and rs6108803). Functional analyses are needed to explore the biological mechanisms underlying these novel genetic associations with risk for bladder cancer.


Harper M.,U.S. National Institute for Occupational Safety and Health | Weis C.,National Institute of Environmental Health science NIEHS | Pleil J.D.,U.S. Environmental Protection Agency | Blount B.C.,Centers for Disease Control and Prevention | And 3 more authors.
Journal of Exposure Science and Environmental Epidemiology | Year: 2015

Exposure science is a holistic concept without prejudice to exposure source. Traditionally, measurements aimed at mitigating environmental exposures have not included exposures in the workplace, instead considering such exposures to be an internal affair between workers and their employers. Similarly, occupational (or industrial) hygiene has not typically accounted for environmental contributions to poor health at work. Many persons spend a significant amount of their lifetime in the workplace, where they maybe exposed to more numerous chemicals at higher levels than elsewhere in their environment. In addition, workplace chemical exposures and other exogenous stressors may increase epigenetic and germline modifications that are passed on to future generations. We provide a brief history of the development of exposure science from its roots in the assessment of workplace exposures, including an appendix where we detail current resources for education and training in exposure science offered through occupational hygiene organizations. We describe existing successful collaborations between occupational and environmental practitioners in the field of exposure science, which may serve as a model for future interactions. Finally, we provide an integrated vision for the field of exposure science, emphasizing interagency collaboration, the need for complete exposure information in epidemiological studies, and the importance of integrating occupational, environmental, and residential assessments. Our goal is to encourage communication and spur additional collaboration between the fields of occupational and environmental exposure assessment. Providing a more comprehensive approach to exposure science is critical to the study of the "exposome", which conceptualizes the totality of exposures throughout a person's life, not only chemical, but also from diet, stress, drugs, infection, and so on, and the individual response. © 2015 Nature America, Inc.


PubMed | U.S. Environmental Protection Agency, National Institute of Environmental Health science NIEHS, U.S. National Institute for Occupational Safety and Health, Jahn Industrial Hygiene and Centers for Disease Control and Prevention
Type: Journal Article | Journal: Journal of exposure science & environmental epidemiology | Year: 2015

Exposure science is a holistic concept without prejudice to exposure source. Traditionally, measurements aimed at mitigating environmental exposures have not included exposures in the workplace, instead considering such exposures to be an internal affair between workers and their employers. Similarly, occupational (or industrial) hygiene has not typically accounted for environmental contributions to poor health at work. Many persons spend a significant amount of their lifetime in the workplace, where they maybe exposed to more numerous chemicals at higher levels than elsewhere in their environment. In addition, workplace chemical exposures and other exogenous stressors may increase epigenetic and germline modifications that are passed on to future generations. We provide a brief history of the development of exposure science from its roots in the assessment of workplace exposures, including an appendix where we detail current resources for education and training in exposure science offered through occupational hygiene organizations. We describe existing successful collaborations between occupational and environmental practitioners in the field of exposure science, which may serve as a model for future interactions. Finally, we provide an integrated vision for the field of exposure science, emphasizing interagency collaboration, the need for complete exposure information in epidemiological studies, and the importance of integrating occupational, environmental, and residential assessments. Our goal is to encourage communication and spur additional collaboration between the fields of occupational and environmental exposure assessment. Providing a more comprehensive approach to exposure science is critical to the study of the exposome, which conceptualizes the totality of exposures throughout a persons life, not only chemical, but also from diet, stress, drugs, infection, and so on, and the individual response.


PubMed | National Institute of Environmental Health science NIEHS, São Paulo State University and University of Sao Paulo
Type: | Journal: BioMed research international | Year: 2014

The increased production of reactive oxygen species (ROS) plays a key role in pathogenesis of diabetic complications. ROS are generated by exogenous and endogenous factors such as during hyperglycemia. When ROS production exceeds the detoxification and scavenging capacity of the cell, oxidative stress ensues. Oxidative stress induces DNA damage and when DNA damage exceeds the cellular capacity to repair it, the accumulation of errors can overwhelm the cell resulting in cell death or fixation of genome mutations that can be transmitted to future cell generations. These mutations can lead to and/or play a role in cancer development. This review aims at (i) understanding the types and consequences of DNA damage during hyperglycemic pregnancy; (ii) identifying the biological role of DNA repair during pregnancy, and (iii) proposing clinical interventions to maintain genome integrity. While hyperglycemia can damage the maternal genetic material, the impact of hyperglycemia on fetal cells is still unclear. DNA repair mechanisms may be important to prevent the deleterious effects of hyperglycemia both in mother and in fetus DNA and, as such, prevent the development of diseases in adulthood. Hence, in clinical practice, maternal glycemic control may represent an important point of intervention to prevent the deleterious effects of maternal hyperglycemia to DNA.


Awada R.,University of Reunion Island | Saulnier-Blache J.S.,French Institute of Health and Medical Research | Gres S.,French Institute of Health and Medical Research | Bourdon E.,University of Reunion Island | And 5 more authors.
Journal of Cellular Biochemistry | Year: 2014

Inflammation is essential in defense against infection or injury. It is tightly regulated, as over-response can be detrimental, especially in immune-privileged organs such as the central nervous system (CNS). Microglia constitutes the major source of inflammatory factors, but are also involved in the regulation of the inflammation and in the reparation. Autotaxin (ATX), a phospholipase D, converts lysophosphatidylcholine (LPC) into lysophosphatidic acid (LPA) and is upregulated in several CNS injuries. LPA, a pleiotropic immunomodulatory factor, can induce multiple cellular processes including morphological changes, proliferation, death, and survival. We investigated ATX effects on microglia inflammatory response to lipopolysaccharide (LPS), mimicking gram-negative infection. Murine BV-2 microglia and stable transfected, overexpressing ATX-BV-2 (A +) microglia were treated with LPS. Tumor necrosis factor α (TNFα), interleukin (IL)-6, and IL-10 mRNA and proteins levels were examined by qRT-PCR and ELISA, respectively. Secreted LPA was quantified by a radioenzymatic assay and microglial activation markers (CD11b, CD14, B7.1, and B7.2) were determined by flow cytometry. ATX expression and LPA production were significantly enhanced in LPS treated BV-2 cells. LPS induction of mRNA and protein level for TNFα and IL-6 were inhibited in A+ cells, while IL-10 was increased. CD11b, CD14, and B7.1, and B7.2 expressions were reduced in A+ cells. Our results strongly suggest deactivation of microglia and an IL-10 inhibitory of ATX with LPS induced microglia activation. J. Cell. Biochem. 115: 2123-2132, 2014. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

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