The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Bernard S Lopez - One of the best experts on this subject based on the ideXlab platform.
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Homologous Recombination is Involved in the Repair Response of Mammalian Cells to Low Doses of Tritium
Radiation Research, 2008Co-Authors: Yannick Saintigny, Stéphane Roche, Delphine Meynard, Bernard S LopezAbstract:Radioactive compounds incorporated in tissues can have biological effects resulting from Energy deposition in subcellular compartments. We addressed the genetic consequences of [(3)H] or [(14)C]thymidine incorporation into mammalian DNA. Low doses of [(3)H]thymidine in CHO cells led to enhanced sensitivity compared with [(14)C]thymidine. Compared with wild-type cells, homologous recombination (HR)-deficient cells were more sensitive to lower doses of [(3)H]thymidine but not to any dose of [(14)C]thymidine. XRCC4-defective cells, however, were sensitive to both low and high doses of [(3)H] and [(14)C]thymidine, suggesting introduction of DNA double-strand breaks, which were confirmed by gamma-H2AX focus formation. While gamma rays induced measurable HR only at toxic doses, sublethal levels of [(3)H] or [(14)C]thymidine strongly induced HR. The level of stimulation was in an inverse relationship to the emitted energies. The RAD51 gene conversion pathway was involved, because [(3)H]thymidine induced RAD51 foci, and [(3)H]thymidine-induced HR was abrogated by expression of dominant negative RAD51. In conclusion, both HR and non-homologous end-joining pathways were involved after labeled nucleotide incorporation (low doses); genetic effects were negatively correlated with the Energy emitted but were positively correlated with the Energy deposited in the nucleus, suggesting that low-Energy Beta-Particle emitters, at non-toxic doses, may induce genomic instability.
Yannick Saintigny - One of the best experts on this subject based on the ideXlab platform.
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Homologous Recombination is Involved in the Repair Response of Mammalian Cells to Low Doses of Tritium
Radiation Research, 2008Co-Authors: Yannick Saintigny, Stéphane Roche, Delphine Meynard, Bernard S LopezAbstract:Radioactive compounds incorporated in tissues can have biological effects resulting from Energy deposition in subcellular compartments. We addressed the genetic consequences of [(3)H] or [(14)C]thymidine incorporation into mammalian DNA. Low doses of [(3)H]thymidine in CHO cells led to enhanced sensitivity compared with [(14)C]thymidine. Compared with wild-type cells, homologous recombination (HR)-deficient cells were more sensitive to lower doses of [(3)H]thymidine but not to any dose of [(14)C]thymidine. XRCC4-defective cells, however, were sensitive to both low and high doses of [(3)H] and [(14)C]thymidine, suggesting introduction of DNA double-strand breaks, which were confirmed by gamma-H2AX focus formation. While gamma rays induced measurable HR only at toxic doses, sublethal levels of [(3)H] or [(14)C]thymidine strongly induced HR. The level of stimulation was in an inverse relationship to the emitted energies. The RAD51 gene conversion pathway was involved, because [(3)H]thymidine induced RAD51 foci, and [(3)H]thymidine-induced HR was abrogated by expression of dominant negative RAD51. In conclusion, both HR and non-homologous end-joining pathways were involved after labeled nucleotide incorporation (low doses); genetic effects were negatively correlated with the Energy emitted but were positively correlated with the Energy deposited in the nucleus, suggesting that low-Energy Beta-Particle emitters, at non-toxic doses, may induce genomic instability.
Delphine Meynard - One of the best experts on this subject based on the ideXlab platform.
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Homologous Recombination is Involved in the Repair Response of Mammalian Cells to Low Doses of Tritium
Radiation Research, 2008Co-Authors: Yannick Saintigny, Stéphane Roche, Delphine Meynard, Bernard S LopezAbstract:Radioactive compounds incorporated in tissues can have biological effects resulting from Energy deposition in subcellular compartments. We addressed the genetic consequences of [(3)H] or [(14)C]thymidine incorporation into mammalian DNA. Low doses of [(3)H]thymidine in CHO cells led to enhanced sensitivity compared with [(14)C]thymidine. Compared with wild-type cells, homologous recombination (HR)-deficient cells were more sensitive to lower doses of [(3)H]thymidine but not to any dose of [(14)C]thymidine. XRCC4-defective cells, however, were sensitive to both low and high doses of [(3)H] and [(14)C]thymidine, suggesting introduction of DNA double-strand breaks, which were confirmed by gamma-H2AX focus formation. While gamma rays induced measurable HR only at toxic doses, sublethal levels of [(3)H] or [(14)C]thymidine strongly induced HR. The level of stimulation was in an inverse relationship to the emitted energies. The RAD51 gene conversion pathway was involved, because [(3)H]thymidine induced RAD51 foci, and [(3)H]thymidine-induced HR was abrogated by expression of dominant negative RAD51. In conclusion, both HR and non-homologous end-joining pathways were involved after labeled nucleotide incorporation (low doses); genetic effects were negatively correlated with the Energy emitted but were positively correlated with the Energy deposited in the nucleus, suggesting that low-Energy Beta-Particle emitters, at non-toxic doses, may induce genomic instability.
Stéphane Roche - One of the best experts on this subject based on the ideXlab platform.
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Homologous Recombination is Involved in the Repair Response of Mammalian Cells to Low Doses of Tritium
Radiation Research, 2008Co-Authors: Yannick Saintigny, Stéphane Roche, Delphine Meynard, Bernard S LopezAbstract:Radioactive compounds incorporated in tissues can have biological effects resulting from Energy deposition in subcellular compartments. We addressed the genetic consequences of [(3)H] or [(14)C]thymidine incorporation into mammalian DNA. Low doses of [(3)H]thymidine in CHO cells led to enhanced sensitivity compared with [(14)C]thymidine. Compared with wild-type cells, homologous recombination (HR)-deficient cells were more sensitive to lower doses of [(3)H]thymidine but not to any dose of [(14)C]thymidine. XRCC4-defective cells, however, were sensitive to both low and high doses of [(3)H] and [(14)C]thymidine, suggesting introduction of DNA double-strand breaks, which were confirmed by gamma-H2AX focus formation. While gamma rays induced measurable HR only at toxic doses, sublethal levels of [(3)H] or [(14)C]thymidine strongly induced HR. The level of stimulation was in an inverse relationship to the emitted energies. The RAD51 gene conversion pathway was involved, because [(3)H]thymidine induced RAD51 foci, and [(3)H]thymidine-induced HR was abrogated by expression of dominant negative RAD51. In conclusion, both HR and non-homologous end-joining pathways were involved after labeled nucleotide incorporation (low doses); genetic effects were negatively correlated with the Energy emitted but were positively correlated with the Energy deposited in the nucleus, suggesting that low-Energy Beta-Particle emitters, at non-toxic doses, may induce genomic instability.
J.l. Riester - One of the best experts on this subject based on the ideXlab platform.
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Monolithic Active Pixel Sensor for charged Particle tracking and imaging using standard VLSI CMOS technology
Nuclear Instruments and Methods in Physics Research Section A: Accelerators Spectrometers Detectors and Associated Equipment, 2001Co-Authors: Renato Turchetta, J. D. Berst, Gilles Claus, Wojciech Dulinski, D. Husson, Yann Hu, Jean-pierre Le Normand, C. Colledani, Barbara Casadei, J.l. RiesterAbstract:A novel Monolithic Active Pixel Sensor (MAPS) for charged Particle tracking made in a standard CMOS technology is proposed. The sensor is a photodiode, which is readily available in a CMOS technology. The diode has a special structure, which allows the high detection efficiency required for tracking applications. The partially depleted thin epitaxial silicon layer is used as a sensitive detector volume. Semiconductor device simulation, using either ToSCA based or 3-D ISE-TCAD software packages shows that the charge collection is efficient, reasonably fast (order of 100 ns), and the charge spreading limited to a few pixels only. A first prototype has been designed, fabricated and tested. It is made of four arrays each containing 64×64 pixels, with a readout pitch of 20 μm in both directions. The device is fabricated using standard submicron 0.6 μm CMOS process, which features twin-tub implanted in a p-type epitaxial layer, a characteristic common to many modern CMOS VLSI processes. Extensive tests made with soft X-ray source (55Fe) and minimum ionizing Particles (15 GeV/c pions) fully demonstrate the predicted performances, with the individual pixel noise (ENC) below 20 electrons and the Signal-to-Noise ratio for both 5.9 keV X-rays and Minimum Ionizing Particles (MIP) of the order of 30. This novel device opens new perspectives in high-precision vertex detectors in Particle Physics experiments, as well as in other application, like low-Energy Beta Particle imaging, visible light single photon imaging (using the Hybrid Photon Detector approach) and high-precision slow neutron imaging.