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An Experimental Comparative Study of the Behaviour of 237Np, 238Pu, 239Pu, 241Am and 242Cm in Bone
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1972
Year
EngineeringRadioactive ContaminationOsteoporosisOrthopaedic SurgeryExperimental Comparative StudyBiomechanicsAnalytical ChemistryToxicologyNuclear MedicineMineral MetabolismRadiologyMechanobiologyBone HealthBone DepositsBone DensityPharmacologyBone MetabolismBone ImagingPhysiologyIntramuscular InjectionMedicinePu-dtpa Complex
Actinides, whether administered by intramuscular injection or by aerosol, had different rates of uptake from the contaminated site and resulted in different bone deposits. Neptunium, esgecially when injected as an acid solution with valence V, had a metabolic fate similar to elements with valence II, yet its urinary excretion was higher than that of the alkaline earths. Because of their valences both curium and americium (valence III) and plutonium (valence IV) could be compared to lanthanides. Following intramuscular injection, 238Pu and 239Pu could be distinguished from americium and curium by a greater uptake in bone. The part played by mass, noticeable after intramuscular injections, was still more noticeable after pulmonary administration. Bone deposits were higher with 238Pu than with 239Pu. A study of the various plutonium compounds or complexes showed that bone burdens decreased as their stability in vivo increased. The smallest bone burden was obtained with the Pu-DTPA complex, the highest one with the Pu-transferrin complex. Bone-seeking actinides could also be distinguished by their histological distribution. Uptake areas were periosteum, perivascular spaces, endosteum, the inner epiphysal plate, metaphysic and marrow. No element seemed to deposit noticeably on the mineral matrix; yet some migrating elements could be found in deep bone, closely connected with the osteocytes and their canaliculi. A rough assessment of actinide bone deposits could be obtained quickly by determining the total amount of urinary excretion of the element prior to any medical treatment. Estimating the bone burden to be twice the cumulative urinary excretion before initiating treatment with DTPA would usually overestimate bone deposition, which would not impair the therapeutic decision. DTPA was effective in treating bone deposits of elements of valence III and IV; they were decreased by one third within 3 months. It has not been determined whether this action will last beyond the fourth month.