Plutonium-239 distribution in the body in relation to the rhythm of administration of an iron preparation

A study was made of the dependence of plutonium distribution among organs and tissues on the time of administration of iron preparation. Iron decreased the share of plutonium in bone tissues, somewhat increased it in soft tissues, and enhanced the excretion of the radionuclide from the organism. The protective efficiency of the preparation in relation to bone tissue was associated with the time of the administration thereof.     

Possibility of a change in the parameters of plutonium-238 metabolism in the body

The influence of macro amounts of iron on 238Pu metabolism in the animal body has been studied. The data obtained indicate that 238Pu metabolism parameters change under the effect of iron. The efficiency of the agent used is demonstrated by a diminished deposition of the radionuclide in bone tissues and an increased (by 2.65 times as compared with the control) excretion of plutonium 238 in faeces.     

Intensification of the excretory flow of plutonium-239 from the body in the late stage of its metabolism

The paper deals with the effect of iron preparations on the excretion of plutonium 239 from a body at a later stage of the radionuclide metabolism. The experimental results show that oral administration of the iron preparation at a later stage of 239Pu metabolism enhances the radionuclide excretion both in urine and in faeces. On the basis of the results obtained the coefficients are calculated for 239Pu excretion in urine and faeces and for its content in the organs of deposition. This may be used for increasing the sensitivity of indirect dosimetry of plutonium-239 within the body.     

Enhanced plutonium absorption in iron-deficient mice.

The total body burden of plutonium 24 or 96 hr following a single gastric intubation was approximately fourfold greater in iron-deficient than in iron-replete mice. There was also a more rapid translocation of plutonium from soft tissues to bone in the iron-deficient mice by 96 hr after gavage. In the iron-replete group only liver concentrations of plutonium increased during the corresponding time period.     

Determination of the plutonium-239 content of the body

In order to increase the informativeness of the indirect dosimetric estimates of plutonium-239 body levels complex makers are widely used to enhance natural excretion of the radionuclide in urine, the ratio between 239Pu levels in urine and skeleton being measured. However, as the onset of chelate application is postponed its efficacy, with respect to the skeleton, sharply decreases making it impossible to obtain reliable information concerning plutonium 239 levels in bone tissues at later times.     

A comparison of the distribution of 239-Pu and calcein in the illium of the female CBA mouse

Conclusions As a model for the behaviour of plutonium in bone, calcein data must be treated with some care. It does not label the same surfaces as plutonium which results in different distribution patterns at later times. However, it might be that if in man or a long lived animal, labelling occured over a period of weeks, so that most surfaces become labelled, the resultant distribution pattern at late times would more nearly model plutonium behaviour. The single biggest difference between the behaviour of the two substances is the build up of plutonium in the bone marrow, an effect seen only slightly with calcein. The other differences noted was the redeposition of plutonium, as a consequence of recycling of the radionuclide, maintaining a concentration of plutonium on endosteal surface.     

Alkaline phosphatase and transaminase activity in the liver and blood serum of rats in the late periods following combined exposure to external gamma radiation and alpha radiation from plutonium-239

A study was made of activity of alkaline phosphatase and alanine- and aspartate aminotransferase in rat liver and blood serum at remote times after external gamma-irradiation combined with internal exposure to 239Pu nitrate delivered in two chronically effective doses. The radionuclide was shown to be mainly responsible for the changes observed in activity of the enzymes under study. The degree to which the changes were manifest depended upon dose of plutonium administered.     

Plutonium in the tissues of foetal, neonatal and suckling mice after Pu-administration to their dams.

Twelve-week-old female (C3H x 101)F1 mice were injected intravenously with an ultrafiltered solution of 239Pu in per cent trisodium citrate, and mated to uninjected PCT males. The plutonium content was examined radiochemically and autoradiographically in placentae and foetuses on the 12th and 18th days of gestation, and in neonates during the 24 hours after birth and also at 18 days postnatally. Plutonium was distributed in most tissues of the late foetus and the suckling as it is in adult mice. However, on both the 12th and 18th days of gestation the concentration in the yolk-sac splanchnopleure was much higher than in any other foetal tissue. The amount of 239Pu in 18-day-old sucklings was between two and seven times as great as in 1-day-old neonates because of ingestion of milk from the lactating dams. In the first litter following administration of the radionuclide to the dam, about 0.02 per cent of the plutonium injected was transferred to an individual offspring by the time of birth, and a further 0.08 per cent by the time of weaning.     

The specificity of the deposition of intratracheally administered plutonium in different skeletal bones with a change in iron homeostasis]

A study was made of the distribution of plutonium-239 injected intratracheally within different bones of the skeleton, the iron status in the blood being changed. The iron preparation caused a 2.5-3-fold decrease in the plutonium loading onto cancellous bone tissue that displayed, in ordinary conditions, a higher tropism to the radionuclide than a cortical highly mineralized bone did.     

Behavior and biological action of 239Pu administered intramuscularly during complexon therapy

With intramuscular injection of 239Pu nitrate the radionuclide content of the rat skeleton was higher, and at the site of injection, lower, than with injection of a polymer plutonium. The animals developed osteosarcomas (nitrate greater than polymer), and at the site of trauma, fibrosarcomas (nitrate less than polymer). After a complexon therapy the dose accretion in the skeleton and liver diminished, the life span increased, and the incidence of sarcomas decreased.     

Radionuclide evaluation of the degree of tissue ischemia in acute thrombosis of the main arteries of the lower extremities

The authors ascertained the value of three-phase scintigraphy using 99mTc pyrophotech (intravenously injected in a dose of 370-500 MBq, radiation exposure 2.1-2.85 mZv) in the diagnosis of disorders of great blood flow and soft tissue blood supply in patients with acute thrombosis of the main arteries, including acute thrombosis caused by injury. Examination of 68 patients with critical ischemia of the lower limbs identified 5 types of 99mTc pyrophotech incorporation into ischemic tissues in main artery thrombosis, embolism and atherosclerotic occlusions. The radionuclide technique in combination with ultrasonography and X-ray contrast angiography has shown it possible to choose adequate treatment policy and to specify the level of amputation and the scope of necrectomy when local muscle necrosis is developed.     

Behavior of plutonium in the body of rats following its intragastric administration in a complex with tributyl phosphate

A study was made of the distribution of plutonium-239 within the rat body after single intragastric administration thereof (1.85 MBq) in a mixture with tributyl phosphate (TBP) and as Pu(IV) nitrate at a time interval from 4 min to 512 days. It was shown that the distribution of the radionuclide was virtually the same but its absorption from the gastrointestinal tract with Pu-TBP was higher by one order of magnitude and exceeded the value recommended by ICRP for soluble plutonium compounds.     

Cytogenetic effects of alpha-irradiation due to incorporated 239Pu

Intravenous injection of plutonium dioxide with 1-2 microns particle sizes in amount of 92.5, 46.3 and 23.2 kBq/kg of body mass increased the yield of chromosome aberrations in bone marrow cells of rats by 3.7, 2.3 and 1.7 times, correspondingly, in comparison with the spontaneous level. The model of chromosome aberration dependence on dose of radionuclide was developed based on the experimental results.     

Decorporation Approach Following Rat Lung Contamination with a Moderately Soluble Compound of Plutonium Using Local and Systemic Ca-DTPA Combined Chelation

Decorporation efficacy of prompt pulmonary delivery of DTPA dry powder was assessed following lung contamination with plutonium nitrate and compared to an intravenous injection of DTPA solution and a combined administration of both DTPA compounds. In addition, efficacy of a delayed treatment was assessed. In case of either early or late administration, insufflated DTPA was more efficient than intravenously injected DTPA in reducing the plutonium lung burden due to its high local concentration. Prompt treatment with DTPA powder was also more effective in limiting extrapulmonary deposits by removing the early transportable fraction of plutonium from lungs prior its absorption into blood. Translocation of DTPA from lungs to blood may also contribute to the decrease in extrapulmonary retention, as shown by reduced liver deposit after delayed pulmonary administration of DTPA. Efficacy of DTPA dry powder was further increased by the combined intravenous administration of DTPA solution for reducing extrapulmonary deposits of plutonium and promoting its urinary excretion. According to our results, the most effective treatment protocol for plutonium decorporation was the early pulmonary delivery of DTPA powder supplemented by an intravenous injection of DTPA solution. Following inhalation of plutonium as nitrate chemical form, this combined chelation therapy should provide a more effective method of treatment than conventional intravenous injection alone. At later stages following lung contamination, pulmonary administration of DTPA should also be considered as the treatment of choice for decreasing the lung burden.     

Plutonium microdistribution in the lungs of Mayak workers

The degree of nonuniform distribution of plutonium in the human lung has not been determined; thus current dosimetric models do not account for nonuniform irradiation. A better scientific basis is needed for assessing the risk of developing radiation-induced disease from inhaled alpha-particle-emitting radionuclides. We measured the distribution of plutonium activity in the lung by autoradiography and related the activity to specific compartments of the lung. The study materials were lung specimens from deceased workers employed by the Mayak Production Association. The approach to analyzing these lung samples used contemporary stereological sampling and analysis techniques together with quantitative alpha-particle autoradiography. For the first time, plutonium distribution has been quantified in the human lung. The distribution of long-term retained plutonium is nonuniform, and a significant portion of plutonium was retained in pulmonary scars. In addition, a large fraction of plutonium was present in the parenchyma, where it was retained much longer than was estimated previously. The sequestration of plutonium particles in scars would greatly reduce the radiation exposure of the critical target cells and tissues for lung cancer. Thus the prolonged retention of plutonium in lung scars may not increase the dose or risk for lung cancer.     

Role of the low-molecular components of the blood serum in determining the biological behavior of plutonium

A study was made of the ability of plutonium to bind to a complex with amino acids, organic and inorganic acids of normal blood serum. Among the low molecular weight addends bicarbonate ions play a major role in plutonium binding. In this respect, possible mechanisms of plutonium metabolism in the blood are discussed.     

Plutonium at the ecosystems of impact zone the Beloyarsk NPP

The distribution of the plutonium at the ecosystems of impact zone the Beloyarsk NPP was studied. Higher quantity of Pu (to 500 Bq/m2) was revealed in the bottom sediments of the Olkhovsk bog where low-level radioactive water of the Beloyarsk NPP have been discharged. The total amount of the radionuclide in a soil cover did not exceed 140 Bq/m2. The contribution of the Beloyarsk NPP to contamination of the investigated ecosystems was accounted with using ratio 238Pu/239.240Pu. It was 64.1-99.3% both in the bottom sediments and soils.     

In vitro and in vivo assessment of plutonium speciation and decorporation in blood and target retention tissues after a systemic contamination followed by an early treatment with DTPA

This study identifies the main sources of systemic plutonium decorporated in the rat after DTPA i.v. at the dose recommended for humans (30 mumol kg(-1)). For this purpose, standard biokinetic approaches are combined to plasma ultrafiltration for separation of plutonium complexes according to their molecular weight. In vitro studies show that at the recommended DTPA dose, less than 5% of the plasma plutonium of contaminated rats can be displaced from high-molecular-weight ligands. After i.v. administration of Pu-DTPA, early ultrafiltrability of plutonium in plasma decreases with total DTPA dose, which is associated with an increase in plutonium bone retention. This demonstrates the instability of Pu-DTPA complexes, injected in vivo, below the minimal Ca-DTPA dose of 30 mumol kg(-1). Plutonium biokinetics is compared in rats contaminated by plutonium-citrate i.v. and treated or not with DTPA after 1 h. No significant decrease in plasma plutonium is observed for the first hour after treatment, and the fraction of low-molecular-weight plutonium in plasma is nearly constant [5.4% compared with 90% in Pu-DTPA i.v. (30 mumol kg(-1)) and 0.7% in controls]. Thus plutonium decorporation by DTPA is a slow process that mainly involves retention compartments other than the blood. Plutonium-ligand complexes formed during plutonium deposition in the retention organs appear to be the main source of decorporated plutonium.     

Preparation and characterization of a DOTA-lysine-biotin conjugate as an effector molecule for pretargeted radionuclide therapy

Pretargeted radionuclide therapy depends on the establishment of a high concentration of secondary binding sites at a tumor to which low-molecular weight radiolabeled effector molecules can be directed. This study describes the simple synthesis of an effector molecule and its subsequent characterization to determine the extent to which it complied with the ideal requirements of such a compound. (Epsilon)-DOTA-(alpha)-biotinamidolysine (DLB) was synthesized in high yield and purity using conventional SPPS methodology. High radiochemical purities were obtained when labeled with several potentially useful radionuclides. The radiolabeled analogue bound to streptavidin efficiently with a stoichiometry similar to that of native biotin and showed high stability in serum and upon challenge with acid conditions. Biodistribution studies in normal animals showed a rapid rate of clearance from the blood and low retention of radioactivity by normal tissues. This design of effector molecule therefore shows promise for further pretargeted radionuclide therapy studies.     

Microcirculatory changes in the tissues surrounding a gunshot wound

An examination was carried out of microcirculation disorders as the main link of the pathogenetic process in the tissues surrounding a gunshot wound. Microcirculatory disorders were assessed in rabbits (924) with the help of radionuclide method (tissue radiometry and scannography) and the method of vital contact microscopy in gunshot wounds of posterior extremity soft tissues. After the injury the formation of four zones of tissue damage was revealed, with different character of microcirculatory changes in wound process dynamics. The obtained data may serve as the basis for working out zonal disorder classification and local treatment of gunshot wounds.