Transcriptional Mutagenesis Induced by 8-Oxoguanine in Mammalian Cells

Most of the somatic cells of adult metazoans, including mammals, do not undergo continuous cycles of replication. Instead, they are quiescent and devote most of their metabolic activity to gene expression. The mutagenic consequences of exposure to DNA–damaging agents are well documented, but less is known about the impact of DNA lesions on transcription. To investigate this impact, we developed a luciferase-based expression system. This system consists of two types of construct composed of a DNA template containing an 8-oxoguanine, paired either with a thymine or a cytosine, placed at defined positions along the transcribed strand of the reporter gene. Analyses of luciferase gene expression from the two types of construct showed that efficient but error-prone transcriptional bypass of 8-oxoguanine occurred in vivo, and that this lesion was not repaired by the transcription-coupled repair machinery in mammalian cells. The analysis of luciferase activity expressed from 8OG:T-containing constructs indicated that the magnitude of erroneous transcription events involving 8-oxoguanine depended on the sequence contexts surrounding the lesion. Additionally, sequencing of the transcript population expressed from these constructs showed that RNA polymerase II mostly inserted an adenine opposite to 8-oxoguanine. Analysis of luciferase expression from 8OG:C-containing constructs showed that the generated aberrant mRNAs led to the production of mutant proteins with the potential to induce a long-term phenotypical change. These findings reveal that erroneous transcription over DNA lesions may induce phenotypical changes with the potential to alter the fate of non-replicating cells

Sulforaphane Potentiates RNA Damage Induced by Different Xenobiotics

Background: The isothiocyanate sulforaphane (SFN) possesses interesting anticancer activities. However, recent studies reported that SFN promotes the formation of reactive oxygen species (ROS) as well as DNA breakage. Methodology/Principal Findings: We investigated whether SFN is able to damage RNA, whose loss of integrity was demonstrated in different chronic diseases. Considering the ability of SFN to protect from genotoxicity, we also examined whether SFN is able to protect from RNA damage induced by different chemicals (doxorubicin, spermine, S-nitroso-Nacetylpenicillamine, H2O2). We observed that SFN was devoid of either RNA damaging and RNA protective activity in human leukemic cells. It was able to potentiate the RNA damage by doxorubicin and spermine. In the first case, the effect was attributable to its ability of modulating the bioreductive activation of doxorubicin. For spermine, the effects were mainly due to its modulation of ROS levels produced by spermine metabolism. As to the cytotoxic relevance of the RNA damage, we found that the treatment of cells with a mixture of spermine or doxorubicin plus SFN increased their proapoptotic potential. Thus it is conceivable that the presence of RNA damage might concur to the overall toxic response induced by a chemical agent in targeted cells. Conclusions/Significance: Since RNA is emerging as a potential target for anticancer drugs, its ability to enhance spermineand doxorubicin-induced RNA damage and cytotoxicity could represent an additional mechanism for the potentiatin

Serum Lipopolysaccharide Binding Protein Levels Predict Severity of Lung Injury and Mortality in Patients with Severe Sepsis

Background: There is a need for biomarkers insuring identification of septic patients at high-risk for death. We performed a prospective, multicenter, observational study to investigate the time-course of lipopolysaccharide binding protein (LBP) serum levels in patients with severe sepsis and examined whether serial serum levels of LBP could be used as a marker of outcome. Methodology/Principal Findings: LBP serum levels at study entry, at 48 hours and at day-7 were measured in 180 patients with severe sepsis. Data regarding the nature of infections, disease severity, development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), and intensive care unit (ICU) outcome were recorded. LBP serum levels were similar in survivors and non-survivors at study entry (117.4±75.7 µg/mL vs. 129.8±71.3 µg/mL, P = 0.249) but there were significant differences at 48 hours (77.2±57.0 vs. 121.2±73.4 µg/mL, P<0.0001) and at day-7 (64.7±45.8 vs. 89.7±61.1 µg/ml, p = 0.017). At 48 hours, LBP levels were significantly higher in ARDS patients than in ALI patients (112.5±71.8 µg/ml vs. 76.6±55.9 µg/ml, P = 0.0001). An increase of LBP levels at 48 hours was associated with higher mortality (odds ratio 3.97; 95%CI: 1.84–8.56; P<0.001). Conclusions/Significance: Serial LBP serum measurements may offer a clinically useful biomarker for identification of patients with severe sepsis having the worst outcomes and the highest probability of developing sepsis-induced ARDS

Thiazolinium and imidazolium chiral ionic liquids derived from natural amino acid derivatives

International audienceStarting from commercially available amino acid derivatives, two novel families of chiral ionic liquids having either a thiazolinium or an imidazolium cation were prepared by simple and straightforward procedures in good overall yields. The properties of these new salts can be finely tuned by careful selection of the anion and the cation

Survenue de symptômes tardifs après un test de provocation par la méthacholine

International audienceThere are few prospective studies available on the development of delayed symptoms following challenge tests with methacholine (MCT) at the currently recommended doses. The objective of this study was to describe the nature and frequency of respiratory symptoms suggestive of bronchospasm developing within 24 hours after a MCT. The study was offered to adult patients who underwent MCT seen consecutively between June and October 2015. Following the test, a questionnaire adapted from the GINA asthma control questionnaire bearing on diurnal and nocturnal symptoms (cough, dyspnoea, wheeze and tightness), was delivered to the patient and the replies collected by telephone 24 hours later. Of the 101 patients included (initial FEV1 2.82 ± 0.79 L), 46 (46 %) were MCT+ and 55 (54 %) MCT−. Among the MCT−, 4 (7 %) presented with immediate symptoms (S+) and 4 (7 %) with delayed symptoms. Among the MCT+ patients, 36 (78 %) presented with immediate symptoms (P < 0.001 compared with the MCT− patients), and 39 (85 %) with delayed symptoms (P < 0.001 compared with the MCT− patients). Delayed symptoms developed with a mean of 5 h 30 after the provocation test. Immediate and delayed symptoms were more frequent in subjects having significant non-specific bronchial hyper-reactivity. Informing patients of the risk of developing delayed symptoms seems useful and allows optimization of their management after a MCT.Peu d’études prospectives sur la survenue de symptômes tardifs (ST) aux doses actuellement recommandées pour les tests de provocation par la méthacholine (TPM) sont disponibles. L’objectif a été de décrire la nature et la fréquence des symptômes respiratoires évocateurs d’un bronchospasme 24 heures après un TPM. L’étude était proposée aux patients adultes adressés consécutivement de juin à octobre 2015 et ayant effectué un TPM. En post-test, un questionnaire, adapté de celui du contrôle de l’asthme du GINA visant au recueil des symptômes diurnes et nocturnes (toux, dyspnée, sibilant, oppression) était remis et les réponses recueillies par téléphone 24 heures après. Sur 101 patients inclus (VEMS initial 2,82 ± 0,79 L), 46 (46 %) étaient TPM+ et 55 (54 %) TPM−. Parmi les TPM−, 4 (7 %) ont présenté des symptômes immédiats (S+) et 4 (7 %) ont présenté des symptômes tardifs (ST+). Parmi les patients TPM+, 36 (78 %) ont présenté des symptômes immédiats (p < 0,001 contre les sujets TPM−) et 39 (85 %) ont présenté des symptômes tardifs (p < 0,001 contre les sujets TPM−). Les symptômes tardifs survenaient en moyenne 5 h 30 après le test de provocation. Les symptômes immédiats et tardifs étaient plus fréquents chez les sujets ayant une hyperréactivité bronchique non spécifique importante. Informer les patients sur le risque de survenue de symptômes respiratoires tardifs apparaît utile et permettra d’optimiser leur prise en charge après un TPM

Effects of prone position and positive end-expiratory pressure on lung perfusion and ventilation

articl

Alveolar recruitment assessed by positron emission tomography during experimental acute lung injury

articleInternational audienc

Effect of activated protein C on pulmonary blood flow and cytokine production in experimental acute lung injury

articl