Toxicogenomic analysis of exposure to TCDD, PCB126 and PCB153: identification of genomic biomarkers of exposure to AhR ligands

<p>Abstract</p> <p>Background</p> <p>Two year cancer bioassays conducted by the National Toxicology Program have shown chronic exposure to dioxin-like compounds (DLCs) to lead to the development of both neoplastic and non-neoplastic lesions in the hepatic tissue of female Sprague Dawley rats. Most, if not all, of the hepatotoxic effects induced by DLC's are believed to involve the binding and activation of the transcription factor, the aryl hydrocarbon receptor (AhR). Toxicogenomics was implemented to identify genomic responses that may be contributing to the development of hepatotoxicity in rats.</p> <p>Results</p> <p>Through comparative analysis of time-course microarray data, unique hepatic gene expression signatures were identified for the DLCs, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (100 ng/kg/day) and 3,3',4,4',5-pentachlorobiphenyl (PCB126) (1000 ng/kg/day) and the non-DLC 2,2',4,4',5,5',-hexachlorobiphenyl (PCB153) (1000 μg/kg/day). A common time independent signature of 41 AhR genomic biomarkers was identified which exhibited at least a 2-fold change in expression following subchronic (13-wk) and chronic (52-wk) p.o. exposure to TCDD and PCB126, but not the non DLC, PCB153. Real time qPCR analysis validated that 30 of these genes also exhibited at least a 2-fold change in hepatic expression at 24 hr following a single exposure to TCDD (5 μg/kg, po). Phenotypic anchoring was conducted which identified forty-six genes that were differently expressed both following chronic p.o. exposure to DLCs and in previously reported studies of cholangiocarcinoma or hepatocellular adenoma.</p> <p>Conclusions</p> <p>Together these analyses provide a comprehensive description of the genomic responses which occur in rat hepatic tissue with exposure to AhR ligands and will help to isolate those genomic responses which are contributing to the hepatotoxicity observed with exposure to DLCs. In addition, the time independent gene expression signature of the AhR ligands may assist in identifying other agents with the potential to elicit dioxin-like hepatotoxic responses.</p

Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

Measurement of differential cross sections and W⁺/W⁻ cross-section ratios for W boson production in association with jets at √s=8 TeV with the ATLAS detector

This paper presents a measurement of the W boson production cross section and the W⁺/W⁻ cross-section ratio, both in association with jets, in proton-proton collisions at √s=8 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb⁻¹. Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W⁺/W⁻ the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton

Corticosteroids and Open-Angle Glaucoma in the Elderly A Population-Based Cohort Study

Background It is largely unknown if corticosteroid-induced open-angle glaucoma (OAG) is an entity that is limited to a few susceptible individuals or whether it contributes significantly to the overall population burden of OAG. Objective The aim of this study was to determine whether there is an association between corticosteroid use and the incidence of OAG in the general elderly population. Methods A prospective population-based cohort study was conducted in a general community setting. 3,939 participants of the Rotterdam Study aged 55 years and older for whom data from ophthalmic examinations at baseline and follow-up were available and who did not have glaucoma at baseline were included (baseline examination from 1991 to 1993; follow-up examinations from 1997 to 1999 and from 2002 to 2006). Ophthalmic examinations, including measurement of the intraocular pressure, assessment of the optic nerve head and perimetry, were performed at baseline and follow-up. The use of corticosteroids was monitored continuously during follow-up. Corticosteroids were stratified into five groups: ophthalmic steroids, inhaled steroids, nasal steroids, oral steroids and steroid ointments. Associations between the use of corticosteroids and incident OAG were assessed using logistic regression models. The study outcome measures were the odds ratios (ORs) of associations between the use of corticosteroids and incident OAG. Results During a mean follow-up of 9.8 years, 108 participants (2.8 %) developed OAG. The median number of steroid prescriptions during follow-up was 2 for ophthalmic, 7 for inhaled, 2 for nasal and 2 for oral steroids, and 3 for steroid ointments. The OR of the use of ophthalmic steroids was 1.04 [95 % confidence interval (CI) 0.66, 1.65; p = 0.86], inhaled steroids 0.79 (95 % CI 0.42, 1.48; p = 0.46), nasal steroids 1.26 (95 % CI 0.74, 2.13; p = 0.40), oral steroids 1.03 (95 % CI 0.65, 1.64; p = 0.89) and steroid ointments 0.70 (95 % CI 0.47, 1.05; p = 0.086). These analyses were adjusted for age, sex, high myopia and family history of glaucoma. The small median numbers of prescriptions made it difficult to evaluate dose-response relationships. Conclusion None of the classes of steroids were associated with the incidence of OAG in this elderly population