PhD subjects

2 sujets INAC

Dernière mise à jour : 19-04-2018


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• Toxicology

 

Noninvasive assays for the assessment of exposure to chemical warfare agents

SL-DRF-18-0555

Research field : Toxicology
Location :

SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SyMMES)

Chimie Interface Biologie pour l’Environnement, la Santé et la Toxicologie (CIBEST)

Grenoble

Contact :

Thierry DOUKI

Starting date : 01-10-2018

Contact :

Thierry DOUKI

CEA - DRF/INAC/SyMMES/CIBEST

0438783191

Thesis supervisor :

Thierry DOUKI

CEA - DRF/INAC/SyMMES/CIBEST

0438783191

Personal web page : http://inac.cea.fr/Pisp/65/thierry.douki.html

Use of chemical warfare agents is a current concern shown in several recent conflicts and associate to terrorist threat. Availability of biomonitoring assays for the identification of toxic compounds and assessment of individual exposure is an important challenge. Sulphur mustard, a chemical warfare agents belonging to the vesicants family, and its simulant CEES will be the focus of this PhD work.

A first class of potential biomarkers are the damage induced to DNA bases by sulphur mustard and CEES. In order to avoid DNA extraction from exposed tissues, we will take advantage of the ability of cells to remove and release the damaged portions of DNA. We will develop an assay for the quantification of these repair products in biological fluids. The other type of biomarkers is related to the detoxification mechanisms used by cells. Electrophilic compounds like sulphur mustard and CEES react, either chemically or enzymatically, with glutathione, a tripeptide present in large amounts in cells. We will develop an analytical approach for the detection of the glutathione-sulphur mustard/CEES conjugates in urine.

For this PhD work, it will be necessary to work first in cultured cells or ex-vivo skin explants in order to define the chemical form and the excretion kinetics of the targeted biomarkers. Analytical tools for the detection these compounds are already available in the group but nothing has been optimized for their isolation from extracellular media or biological fluids. The analytical developments will thus focus on sample preparation using solid phase extraction techniques followed by quantification by HPLC associated to mass spectrometry. These approaches validated for the quantification of the biomarkers in biological fluids will be applied to animal studies in collaboration with the Military Biomedical Research Institute.

Monitoring formation and repair of DNA damage by a non-invasive assay

SL-DRF-18-0317

Research field : Toxicology
Location :

SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SyMMES)

Chimie Interface Biologie pour l’Environnement, la Santé et la Toxicologie (CIBEST)

Grenoble

Contact :

Thierry DOUKI

Starting date : 01-10-2018

Contact :

Thierry DOUKI

CEA - DRF/INAC/SyMMES/CIBEST

0438783191

Thesis supervisor :

Thierry DOUKI

CEA - DRF/INAC/SyMMES/CIBEST

0438783191

A wide variety of physical and chemical agents may damage the chemical structure of DNA, and in particular nucleic bases. As a consequence, mutations are produced that may trigger the cancerization of the damage cell. Fortunately, all cells have developed a series of enzymatic processes that can repair the damaged portion of DNA and limit the deleterious consequences of the damage. The effect of genotoxic agents results thus from the balance between the formation and the repair of DNA damage.

Monitoring the formation of DNA damage in Human requires collection of tissues, followed by extraction of DNA and analysis. Although internal organs may sometimes be studied when biopsies are taken in patients, samples available in the general population or at the working place are limited to skin biopsies and blood cells. Biopsies is a rather invasive procedure and the nature of the damage in blood cells does not represent the whole body exposure. Some limitations are also encountered in in vitro experiments. There is thus a need for less invasive procedures and more representative data.

In the present PhD project, we want to quantify the damages bases released from DNA by the repair enzymes. In particular, we want to quantify bulky adducts and photoproducts resulting from exposure to solar light. The work will first involve extensive analytical chemistry developments, using mostly solid phase extraction and HPLC associated to mass spectrometry. On-line HPLC preparation of the samples will also be investigated. The method will be then validated on cultured cells. Last, the protocol will be extended to the detection of repair products in biological fluids like urine for in vivo investigations. The technique will be applied to three main topics: the formation of photoproducts induced by solar UV in skin and its prevention by sunscreens (collaboration with the Pierre Fabre Dermo-Cosmétique company), the induction of adducts with pollutants like polycyclic aromatic hydrocarbons, and the formation of adducts between DNA and CEES, an analog of sulfur mustard (collaboration with the Military Biomedical Research Institute).

 

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