The Experts below are selected from a list of 1350 Experts worldwide ranked by ideXlab platform
A Van Der Meeren - One of the best experts on this subject based on the ideXlab platform.
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Early Inflammatory Changes in Lung Following PuO2 or Pu Nitrate Contamination in the Rat
EDP Sciences, 2008Co-Authors: A Van Der Meeren, O. Gremy, F. Tourdes, M.-c. Abram, Q. Chau, D. Renault, J.-l. Poncy, N. GriffithsAbstract:Increases in cancer incidence and mortality among workers overexposed to alpha-emitting radionuclides, such as plutonium (Pu), have been described with Lung tumors of epithelial origin being the most common. However, the question of mechanisms leading to tumor formation following inhalation of radionuclides remains. The main factor controlling tumor incidence seems to be associated with radiation dose distribution, the more homogenous the distribution, the higher the incidence of cancer. In addition, some evidence exists regarding the role of the inflammatory response as a cofactor of tumorigenesis. The present study aims to determine the early inflammatory changes following pulmonary Pu contamination with the insoluble compound, PuO2 or the moderately soluble compound, Pu nitrate. Adult male Sprague-Dawley rats were exposed to PuO2 aerosols using a nose-only inhalation procedure (Initial Lung Deposit 4.7-43.4 kBq), or received intratracheal administration of Pu nitrate (25 kBq). Fourteen days post contamination, rats were euthanized and bronchoalveolar lavages (BAL) carried out. Activity was measured by liquid scintillation in Lungs, femurs and liver. Distribution of activity within Lung compartments was also studied. Activation of alveolar macrophages was evaluated by measurement of inflammatory mediators in supernatants collected 24h after plating and intracellular acid phosphatase activity determination, as well as by CD68 immunolabelling on Lungs. The higher solubility of Pu nitrate as compared to PuO2 is illustrated by higher activity Deposits in skeleton and liver, and lower retention in Lungs. However, at this time point, Lung distribution does not vary between the 2 compounds, the majority of activity being retained in the cellular fraction of BAL, mainly macrophages. Activation of macrophages is observed in the two groups of contaminated animals, with an enhanced production of TNF-alpha, MCP-1, CINC-1 and MIP-2, and an increased acid phosphatase activity, as compared to sham-contaminated rats. The level of activation was found to be dependant on the initial Lung Deposit following PuO2 contamination. Our results provide evidence for an early inflammatory response following Pu Lung contamination and the role of macrophages whatever the solubility of the Pu compound
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influence of initial Lung Deposit on pulmonary clearance after plutonium oxide inhalation in rat
Radiation Protection Dosimetry, 2007Co-Authors: A Van Der Meeren, G Grillon, Francoise Tourdes, S Rateau, Le B Gall, N M GriffithsAbstract:Alveolar macrophages are a key element in the clearance of inhaled particles after phagocytosis, and thus participate actively in Lung dose distribution and in the risk of tumour formation. We studied the influence of initial Lung Deposit (ILD) on Lung clearance and distribution of activity from 3 d to 3 months after inhalation of two forms of PuO2 (97% 239Pu and 70% 239Pu) in rats. ILDs ranging from 2.1 to 17 kBq were used. The total activity measured using X-ray spectrometry 3 months post-inhalation, relative to the ILD, showed a similar decrease in all groups, with the remaining activity representing approximately 30% of the ILD. The total activity recovered in bronchoalveolar lavages represented approximately 60% of the total Lung activity. This ratio remained stable over time for the lowest ILD tested but decreased for higher ILD. In addition, the percentage of macrophages associated with particles decreased faster with time in rats with the highest ILD. Under our experimental conditions, there were no marked differences in Lung clearance between groups. However, the distribution of the activity seems to vary with the time post-exposure between low and high ILD.
Jorma Jokiniemi - One of the best experts on this subject based on the ideXlab platform.
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industrial worker exposure to airborne particles during the packing of pigment and nanoscale titanium dioxide
Inhalation Toxicology, 2012Co-Authors: Antti J Koivisto, Jussi Lyyranen, Ari Auvinen, Esa Vanhala, Kaarle Hameri, Timo Tuomi, Jorma JokiniemiAbstract:Context: Titanium dioxide (TiO2) factory workers’ source specific exposure and dose to airborne particles was studied extensively for particles between 5 nm and 10 μm in size.Objective: We defined TiO2 industry workers’ quantitative inhalation exposure levels during the packing of pigment TiO2 (pTiO2) and nanoscale TiO2 (nTiO2) material from concentrations measured at work area.Methods: Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A Lung Deposit model was used to calculate regional inhalation dose rates in units of particles min−1 and μg min−1 without use of respirators.Results: Workers’ average exposure varied from 225 to 700 μg m−3 and from 1.15 × 104 to 20.1 × 104 cm−4. Over 90% of the particles were smaller than 100 nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO2 and nTiO2 agglomerates. The ...
N M Griffiths - One of the best experts on this subject based on the ideXlab platform.
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influence of initial Lung Deposit on pulmonary clearance after plutonium oxide inhalation in rat
Radiation Protection Dosimetry, 2007Co-Authors: A Van Der Meeren, G Grillon, Francoise Tourdes, S Rateau, Le B Gall, N M GriffithsAbstract:Alveolar macrophages are a key element in the clearance of inhaled particles after phagocytosis, and thus participate actively in Lung dose distribution and in the risk of tumour formation. We studied the influence of initial Lung Deposit (ILD) on Lung clearance and distribution of activity from 3 d to 3 months after inhalation of two forms of PuO2 (97% 239Pu and 70% 239Pu) in rats. ILDs ranging from 2.1 to 17 kBq were used. The total activity measured using X-ray spectrometry 3 months post-inhalation, relative to the ILD, showed a similar decrease in all groups, with the remaining activity representing approximately 30% of the ILD. The total activity recovered in bronchoalveolar lavages represented approximately 60% of the total Lung activity. This ratio remained stable over time for the lowest ILD tested but decreased for higher ILD. In addition, the percentage of macrophages associated with particles decreased faster with time in rats with the highest ILD. Under our experimental conditions, there were no marked differences in Lung clearance between groups. However, the distribution of the activity seems to vary with the time post-exposure between low and high ILD.
Antti J Koivisto - One of the best experts on this subject based on the ideXlab platform.
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industrial worker exposure to airborne particles during the packing of pigment and nanoscale titanium dioxide
Inhalation Toxicology, 2012Co-Authors: Antti J Koivisto, Jussi Lyyranen, Ari Auvinen, Esa Vanhala, Kaarle Hameri, Timo Tuomi, Jorma JokiniemiAbstract:Context: Titanium dioxide (TiO2) factory workers’ source specific exposure and dose to airborne particles was studied extensively for particles between 5 nm and 10 μm in size.Objective: We defined TiO2 industry workers’ quantitative inhalation exposure levels during the packing of pigment TiO2 (pTiO2) and nanoscale TiO2 (nTiO2) material from concentrations measured at work area.Methods: Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A Lung Deposit model was used to calculate regional inhalation dose rates in units of particles min−1 and μg min−1 without use of respirators.Results: Workers’ average exposure varied from 225 to 700 μg m−3 and from 1.15 × 104 to 20.1 × 104 cm−4. Over 90% of the particles were smaller than 100 nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO2 and nTiO2 agglomerates. The ...
E Ansoborlo - One of the best experts on this subject based on the ideXlab platform.
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the effects of the initial Lung Deposit on uranium biokinetics after administration as uf4 and uo4
International Journal of Radiation Biology, 1999Co-Authors: P Houpert, V Chazel, F Paquet, M H Hengenapoli, E AnsoborloAbstract:This study was designed to assess the effect of the initial Lung Deposit (ILD) on uranium biokinetics in rats after intracheal instillation of biologically soluble uranium compounds. Rats received various doses of either UO4 or UF4 dust. The uranium content was determined in the kidneys, Lungs, remaining carcass, urine and faeces at intervals of up to 30 days. The percentages of uranium absorbed into blood, transferred to tissues, and excreted in urine were independent of the uranium Lung Deposit for the two compounds. The K/K+U ratio 24 h after installation (K is the per cent of uranium retained in the kidneys and U the per cent excreted in urine) which can be used to evaluate kidney function, was essentially constant in the range from 0.02 to 12.5 mugUg-1 kidneys.
