ABSTRACT
PURPOSE: To compare specific absorption parameter values obtained from in vitro dissolution studies (this paper) and in vivo experiments (data published by Ramounet et al, 2000) and to determine their influence on Dose Per Unit Intake (DPUI) calculations. MATERIALS AND METHODS: Experiments were performed on plutonium oxide (PuO2) and two Mixed Oxide (MOx) preparations containing 5% Pu (w/w) made according to the industrial process in vitro using a static test and in vivo after rat inhalation. RESULTS: Behaviour of Pu and Am shows, in vitro, at shorter times, a greater rapid dissolution fraction f(r) for Pu (factor 10) and Am (factor 2) with MOx powders compared with PuO2, whereas in vivo results show a greater fraction f(r) for Pu (factor 5) and Am (factor 15) with PuO2 compared with MOx powders. This phenomenon has not been observed for slow dissolution absorption parameter s(s). The in vivo parameters for Pu and Am in these materials were very close to the default values recommended by International Commission for Radiological Protection for default Type S. CONCLUSIONS: Results obtained have shown that solubility of Pu from the mixed oxide was higher than that of Pu from PuO2. Nevertheless, no significant difference was observed between the three compounds in the corresponding dose coefficients in vivo or in vitro. Therefore, for these particular compounds, variation in the chemical composition of the aerosols had no significant influence on DPUI. Consequently, in vitro, the dissolution test can provide a good estimate of the in vivo behaviour. Studies of variation of % Pu (w/w) from MOx are in progress in our laboratory to confirm these conclusions.
Subject(s)
Aerosols , Inhalation/radiation effects , Oxides/pharmacokinetics , Plutonium/pharmacokinetics , Absorption , Animals , Dose Fractionation, Radiation , Inhalation/physiology , Lung/metabolism , Metabolic Clearance Rate , Rats , Tissue DistributionABSTRACT
PURPOSE: To compare the biokinetics of Pu and Am in rat after inhalation of PuO2 and two (U, Pu) mixed oxides (MOX), referred to as MIMAS and SOLGEL. MATERIALS AND METHODS: Lung clearance was measured in vivo by X-and y-ray spectrometry. Retention of Pu and Am in femurs, liver and kidneys was measured by alpha-spectrometry. RESULTS: Observed lung clearance was in the same range for all three powders. Extra-pulmonary transfers were expressed as the percent of the initial deep lung deposit (IDLD) measured 7 days after inhalation. After PuO2 exposure, bone retention remained nearly constant throughout the 270-day experiment. It was approximately 0.7% of the IDLD for Pu and Am. By contrast, a gradual increase was observed for the two MOX. After 7 days, bone retention of Pu and Am was respectively 0.05 and 0.08% for MIMAS, and 0.2 and 0.6% for SOLGEL. The retention reached maximal values between 180 and 270 days post-exposure, which were 0.2 and 0.3% for MIMAS, and 1.2 and 2.8% for SOLGEL for Pu and Am respectively. CONCLUSIONS: Different transfer rates of Pu and Am from the lung were observed depending on the chemical composition of the oxides and/or the method of their preparation.
Subject(s)
Americium/pharmacokinetics , Plutonium/pharmacokinetics , Administration, Inhalation , Animals , Lung/metabolism , Male , Metabolic Clearance Rate , Rats , Rats, Sprague-DawleyABSTRACT
An unusual twin pregnancy was diagnosed echographically at 18 weeks gestation and confirmed by magnetic resonance imaging. One foetus was in a pseudo unicornis uterus and the other in a rudimentary uterus cornu. The risk in such cases, as also reported in the literature, is rupture of the rudimentary cornu at about 20 weeks gestation. In this case the patient was carefully monitored to 23 weeks when the pregnancy in the rudimentary cornu stopped spontaneously. The foetus in the pseudounicornis developed normally to 38 week term. This exceptional observation emphasizes the risk of pregnancy in a blind uterus cornu.
