Biomedical subjects

E Ansoborlo

Publications and source records attributed to E Ansoborlo.

29 records · Page 2Linked to original sources

PubMed1999

Intracellular behaviour of uranium(VI) on renal epithelial cell in culture (LLC-PK1): influence of uranium speciation.

The main objective of this work was to assess the potentiality of in vitro models to study and understand the uranium-induced cytotoxicity on renal cells. Cytotoxicity and morphological studies were performed in a tubular proximal original established cell line (LLC-PK1 cell line). Dose-dependent cytotoxicity response was obtained with the uranium bicarbonate complex. In vitro experiments revealed a toxicity of uranium-bicarbonate complexes after a 24-h exposition and for concentrations ranging from 7 x 10(-4) M to 10(-3) M. In contrast, a lack of cytotoxicity of uranium(VI) citrate complexes studied using the same experimental conditions was noticed. Furthermore, electron transmission microscopy and X-ray microanalysis studies, after exposition of LLC-PK1 cells to the uranium-bicarbonate system ([U] = 8 x 10(-4) M) revealed that uranium entered into the cells and it was precipitated within the cytoplasmic compartment as uranyl phosphate needles. Similar morphological studies conducted with citrate complexes did not show any intake of uranium by LLC-PK1 cells. Experiments conducted in phosphate free culture medium showed that uranium was incorporated as a soluble material and that the association of the metal with phosphate ions occurred in the cytoplasmic compartment of LLC-PK1 cells.

Animals↗

PubMed1999

Efficacy of ethane-1-hydroxy-1,1-bisphosphonate (EHBP) for the decorporation of uranium after intramuscular contamination in rats.

PURPOSE: To obtain compounds that will effectively reduce the fixation of uranium in its main target organs: bone and kidney. There is an urgent need for a chelating agent that is suitable and available for human use. MATERIALS AND METHODS: The efficacy of ethane-1-hydroxy-1,1-bisphosphonate (EHBP), already in use as a therapeutic agent, was investigated in animal experiments. The effect of different treatment regimens was investigated on rats (EHBP: 50-100 micromol kg(-1); ligand/uranium ratio 2500 to 5000). RESULTS: The present study shows that one prompt injection of EHBP reduced uranium deposition in kidneys by a factor of five after acute intramuscular contamination in rats. At the same time, the total body uranium in the treated animals was 70% of controls. When the treatment was delayed 30 min after contamination, the kidney content was still reduced by a factor of two. CONCLUSIONS: EHBP has the advantage of clinical acceptance as a therapeutic agent for other purposes and its toxicity has been well studied. It therefore has a role in the treatment of human contamination with uranium.

Animals↗

PubMed1999

The effects of the initial lung deposit on uranium biokinetics after administration as UF4 and UO4.

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 microg U g(-1) kidneys.

Animals↗

PubMed1999

Review and critical analysis of available in vitro dissolution tests.

The procedures recommended in Publications 30 and 66 by ICRP for calculating radiation doses from inhaled or ingested radionuclides include classification of material on the basis of different parameters, among which transportability plays a major role, The allocation of transportable Classes or absorption Types should, whenever possible, be based on animal or human data. However, when such in vivo data are unavailable, it becomes appropriate to consider the use of other approaches, among which in vitro dissolution techniques are reasonable alternatives. This paper reviews and critically analyzes in vitro dissolution techniques that have been described historically and recommends methods shown to be useful in estimating the in vivo solubility of radioactive particles.

Administration, Inhalation↗

PubMed1999

Influence of uranium(VI) speciation for the evaluation of in vitro uranium cytotoxicity on LLC-PK1 cells.

Very few data are available concerning the in vitro toxicity of uranium. In this work, we have determined the experimental chemical conditions permitting the observation of uranium(VI) cytotoxicity on LLC-PK1 cells. Uranium solutions made either by dissolving uranyl acetate or nitrate crystals, or by complexing uranium with bicarbonate, phosphate or citrate ligands, were prepared and tested. Experiments demonstrated that only uranium solutions containing citrate and bicarbonate ligands concentrations tenfold higher than the metal, were soluble in the cell culture medium. Cytotoxicity studies of all these uranium compounds were performed on LLC-PK1 cells and compared using LDH release, neutral red uptake and MTT assays. Dose dependent cytotoxicity curves were only obtained with uranium-bicarbonate medium. This study has revealed a toxicity of uranium-bicarbonate complexes for 24 h expositions and for concentrations ranging from 7 x 10(-4)-10(-3) M, under these conditions, the CI50 (cytotoxicity index) was evaluated between 8.5 and 9 x 10(-4) M. In contrast, we noticed a lack of cytotoxicity response for uranium(VI)-citrate complexes. Electron transmission microscopy studies revealed, when LLC-PK1 cells were exposed to the uranium-bicarbonate system, that uranium penetrated and precipitated within the cytoplasmic compartment. Morphological studies conducted with citrate complexes did not show any cellular intake of uranium.

Animals↗

PubMed1998

Assessment of physico-chemical and biokinetic properties of uranium peroxide hydrate UO4.

Comprehensive studies on the radiotoxicological risk of an intermediate compound UO4, which is not specified in ICRP Recommendations, were motivated by its increased use in the nuclear fuel cycle and the lack of information such as physico-chemical and biokinetic properties. The aim of this work was to give an experimental basis for assessing the appropriate limits on intake for workers exposed to UO4 and to provide guidance for the interpretation of personal monitoring data. Particle size measurement of the UO4 dust indicated a geometric diameter D of 0.5 microm, which corresponds to an activity median aerodynamic diameter (AMAD) of 1.1 microm. In vitro experiments conducted in culture medium showed that UO4 is a soluble compound with 66.2% dissolved in 1.9 d and 33.8% in 78 d. Results of dissolution obtained with macrophages showed a significant decrease of 50% at 1 d in terms of solubility. Biokinetic data in the rat obtained from two in vivo studies involving intratracheal instillation in rats indicated half-times in the lung of 0.5 d (96.6%) and 27 d (3.4%) for an initial lung deposit (ILD) of 195 microg, and 1.2 d (90.3%) and 38 d (9.7%) for an ILD of 7.6 microg. Absorption parameters to blood as defined in the ICRP Publication 66 human respiratory tract model were calculated with the specific software GIGAFIT and led to the rapid fraction fr (0.800 to 0.873), the rapid rate sr (0.525 to 0.928 d(-1)), and the slow rate ss (1.57 x 10(-2) to 2.42 x 10(-3) d(-1)). Effective dose coefficients by inhalation for this UO4 compound using the in vivo experimental results were calculated to be between 0.52 and 0.70 x 10(-6) Sv Bq(-1). Comparison of these values with effective dose coefficients defined in ICRP Publication 68 for workers showed that UO4 could be considered as a fast soluble compound of Type F.

Animals↗

PubMed1997

Role of alveolar macrophage lysosomes in metal detoxification.

The intracellular behaviour of different toxic mineral elements inhaled as soluble aerosols or as insoluble particles was studied in the rat by electron microscopy, electron probe microanalysis, and electron microdiffraction. This study showed that, after inhalation, aerosols of soluble elements like cerous chloride, chromic chloride, uranyl nitrate, and aluminium chloride, are concentrated in the lysosomes of alveolar macrophages and are precipitated in the lysosomes in the form of insoluble phosphate, probably due to the activity of acid phosphatase (intralysosomial enzyme). Also, after inhalation of crystalline particles that are insoluble or poorly soluble in water such as the illites (phyllosilicates), ceric oxides (opaline), and industrial uranium oxides (U3O8), the small crystals are captured by the alveolar macrophage lysosomes and transformed over time into an amorphous form. This structural transformation is associated with changes in the chemical nature of particles inhaled in the oxide form. Microanalysis of amorphous deposits observed after inhalation of uranium or ceric oxides has shown that they contain high concentrations of phosphorus associated with the initial elements cerium and uranium. These different processes tend to limit the diffusion of these toxic elements within the organism, whether they are inhaled in soluble form or not.

Aerosols↗

PubMed1996

Role of alveolar macrophages in the dissolution of two different industrial uranium oxides.

This study was aimed at assessing and understanding some mechanisms involved in the intracellular particle transformation of two uranium oxides (U3O8 and UO2 + Umetal) produced by a new isotopic enrichment plant using laser technology. Instillations were conducted on rats with both uranium compounds and alveolar macrophages were harvested at different dates and prepared in order to be studied using transmission electron microscopy and electron energy loss spectrometry (EELS). The presence of particles in the cells was observed from the first day after instillation, and crystalline needles of uranyl phosphate appeared in the cytoplasm of the cells. These needles were more numerous after instillation with the mixture UO2 + Umetal than after administration of U3O8 and may be correlated with the higher solubility of UO2 + Umetal observed in vitro. The formation of insoluble needles in lysosomes is consistent with the insolubilisation of uranium observed after phagocytosis by alveolar macrophages.

Air Pollutants, Occupational↗

PubMed1995

Efficacy of 3,4,3-LIHOPO for reducing the retention of uranium in rat after acute administration.

Decorporation therapy is the only known effective method of reducing the radiation dose to persons following accidental internal contamination with transportable radionuclides. Deposits of actinides in bone should be minimized because development of osteosarcoma appears to be related to internal exposure. In contrast with other actinides, such as plutonium or americium where chelating agent treatment is efficient, the therapeuric approaches used for cases of uranium contamination are widely ineffective. This is the first report on in vivo efficacy of a chelating agent, a siderophore analogue code named 3,4,3-LIHOPO, after systematic exposure to natural uranium in the rat. Using the classical antidotal therapy (sodium bicarbonate) for comparison, this ligand has been investigated for its ability to remove uranium from rats after intravenous or intramuscular injection as nitrate. Following an immediate single intramuscular or intravenous injection of 3,4,3-LIHOPO (30 mumol.kg-1) urinary excretion of uranium was greatly enhanced with a corresponding reduction 24 h later in kidney and bone uranium content (to about 20 and 50% of the control rat respectively). Under identical experimental conditions, sodium bicarbonate (640 mumol.kg-1) reduced the uranium content in kidney in kidney and bone only to about 90 and 70% of controls respectively, and there was less enhancement of uranium excretion. However, when treatment was delayed by 30 min and administered intraperitoneally, there was no marked difference in retention and excretion of uranium between the two compounds. As this ligand showed no apparent irreversible toxicity at effective dosages, it is concluded that the administration of the 3,4,3-LIHOPO chelating agent represents potentially a most significant advance for prompt treatment of uranium contamination, while a more detailed investigation is necessary on the possible advantage when treatment delayed.

Animals↗

PubMed1992

In vitro chemical and cellular tests applied to uranium trioxide with different hydration states.

A simple and rapid in vitro chemical solubility test applicable to industrial uranium trioxide (UO3) was developed together with two in vitro cellular tests using rat alveolar macrophages maintained either in gas phase or in alginate beads at 37 degrees C. Industrial UO3 was characterized by particle size, X-ray, and IR spectra, and chemical transformation (e.g., aging and hydration of the dust) was also studied. Solvents used for the in vitro chemical solubility study included carbonates, citrates, phosphates, water, Eagle's basal medium, and Gamble's solution (simulated lung fluid), alone, with oxygen, or with superoxide ions. Results, expressed in terms of the half-time of dissolution, according to International Commission on Radiological Protection (ICRP) classification (D,W,Y), varied for different hydration states of UO3, showing a lower solubility of hydrated UO3 in solvents compared to basic UO3 or UO3 heated at 450 degrees C. Two in vitro cellular tests on cultured rat alveolar macrophages (cells maintained in gas phase and cells immobilized in alginate beads) were used on the same UO3 samples and generally showed a lower solution transfer rate in the presence of macrophages than in the culture medium alone. The results of in vitro chemical and cellular tests were compared, with four main conclusions: a good reproducibility of the three tests in Eagle's basal medium the effect of hydration state on solubility, the classification of UO3 in terms of ICRP solubility criteria, and the ability of macrophages to decrease uranium solubility in medium.

Animals↗

PubMed1990

In vitro solubility of uranium tetrafluoride with oxidizing medium compared with in vivo solubility in rats.

A simple in vitro solubility test for uranium tetrafluoride (UF4) was developed to investigate the effects of addition of enzymes, proteins or gases such as O2 to synthetic biological fluid or Gamble solvent. The tests were conducted concomitantly with an in vivo inhalation experiment using male rats. In the presence of Gamble solvent alone, UF4 exhibited class Y behaviour with a dissolution half-time of 300-500 days. However, when oxygen or carbonates were added to the Gamble solvent, UF4 displayed class W behaviour, with a half-time of 25-50 days. Lastly, in the presence of oxygen and pyrogallol, which simulates the action of the enzyme NADPH, the superoxide ion (O2-) was formed, which appears to have a dominant role in the oxidation of U4+ to U6+. Under these conditions UF4 behaved like a class D compound, and had a dissolution half-time of only 2-3 days. These latter results correlated with those of the inhalation experiment in which the dissolution half-time was calculated to be between 2.5 and 5.2 days. The data are also in agreement with urine monitoring data obtained for workers exposed to UF4 over a 20-year period.

Administration, Inhalation↗