Chronic exposure to low concentrations of strontium 90 affects bone physiology but not the hematopoietic system in mice

Correlation of phosphorus level with macro- and microelements in the bristles of Landrace pigs

The presented results expand the understanding of the normal chemical composition of the body. The study was carried out on the basis of a pig-breeding farm in the Altai Territory in 2016-2020 on clinically healthy 6-month-old pigs of the Landrace breed. Chemical analysis of pig bristles was performed by inductively coupled plasma atomic emission spectrometry. The data were processed using Statistica 8 software (StatSoft Inc., USA). A study of the correlations between phosphorus in bristles and other macro-, microelements, as well as chemical elements associated with phosphorus, has been carried out. Only positive connections of different strengths have been established between phosphorus and elements involved in the formation of bone tissue (calcium, magnesium, manganese), copper, iron and strontium. There are two groups of direct interactions of different strengths between the chemical elements associated with phosphorus. Explained supposedly the essence of the connections, which is consistent in the bristle, as the final site of exchange, with organs and tissues of mammals.

Direct ceramic coating of calcium phosphate doped with strontium via reactive growing integration layer method on α-Ti alloy

A strontium (Sr)-doped hydroxyapatite-like coating was deposited on α-Ti alloy via the growing integration layer (GIL) method at various applied voltages. We added 0.03 M strontium hydroxide (Sr(OH)2·8H2O) to a solution containing calcium acetate and sodium dihydrogen phosphate to produce Sr-doped hydroxyapatite (Sr-HA) coatings. The scanning electron microscope (SEM) images of these coatings showed that all various features, such as average pore size, coating thickness, micro-hardness, and roughness, were similar to those of HA. As the voltage increased from 250 to 300 V, the amount of micro cracks decreased, and there were eliminated at 350 V. The SEM images also showed that the Sr-HA coatings were closely integrated with the alloy: without any gaps between the oxide layers and the alloy. In addition, energy-dispersive X-ray spectroscopy verified the Sr integration from the bottom up. X-ray diffraction patterns confirmed Sr-HA formation instead of calcium phosphate, even at the lowest voltage of 250 V. The value of Ecorr increased by 6.6% after raising the voltage from 250 to 350 V. The electrochemical impedance spectroscopy analysis confirmed that the adequate corrosion resistance of Sr-HA coatings, especially at the highest voltage of 350 V. In addition, the GIL treatment increased the layer resistance measured by Rp/Rc. Optimally, the GIL method used the highest voltage of 350 V to produce higher quality of Sr-HA-rich coatings.

Application of rodes software to experimental biokinetic data for dose assessment in mice and rats

H Miloudi, M Locatelli, G Autret, D Balvay, A Desbrée, E Blanchardon, J M Bertho: application of RODES software to experimental biokinetic data for dose assessment in mice and rats. In support of experimental studies of chronic, long-term contamination in rodents, voxel-based computer models were built representing adult mice and juvenile, adult and elderly rats of both sexes. RODES software was created to calculate absorbed radiation doses to organs with these specific anatomical models. Absorbed doses were then calculated starting from previously published biokinetic data. Whole body doses showed less than 5% differences between calculation with RODES and calculation with the ICRP Publication 108 model for long term exposure to ⁹⁰Sr of mice. Similar results were obtained for long term exposure to ¹³⁷Cs. Dose distribution for ⁹⁰Sr internal contamination also showed that the dose to the skeleton is six fold more as compared to the whole body dose while radiation dose to other organs is less than the mean whole body dose. These results underline the importance of using specific anatomical models according to the age and the sex of experimental animals.

RODES software for dose assessment of rats and mice contaminated with radionuclides

In order to support animal experiments of chronic radionuclides intake with realistic dosimetry, voxel-based three-dimensional computer models of mice and rats of both sexes and three ages were built from magnetic resonance imaging. Radiation transport of mono-energetic photons of 11 energies and electrons of 7 energies was simulated with MCNPX 2.6c to assess specific absorbed fractions (SAFs) of energy emitted from 13 source regions and absorbed in 28 target regions. RODES software was developed to combine SAF with radiation emission spectra and user-supplied biokinetic data to calculate organ absorbed doses per nuclear transformation of radionuclides in source regions (S-factors) and for specific animal experiments with radionuclides. This article presents the design of RODES software including the simulation of the particles in the created rodent voxel phantoms. SAF and S-factor values were compared favourably with published results from similar studies. The results are discussed for rodents of different ages and sexes.

DNA damage induced by Strontium-90 exposure at low concentrations in mesenchymal stromal cells: the functional consequences

⁹⁰Sr is one of the radionuclides released after nuclear accidents that can significantly impact human health in the long term. ⁹⁰Sr accumulates mostly in the bones of exposed populations. Previous research has shown that exposure induces changes in bone physiology both in humans and in mice. We hypothesize that, due to its close location with bone marrow stromal cells (BMSCs), ⁹⁰Sr could induce functional damage to stromal cells that may explain these biological effects due to chronic exposure to ⁹⁰Sr. The aim of this work was to verify this hypothesis through the use of an in vitro model of MS5 stromal cell lines exposed to 1 and 10 kBq.mL^-1 of ⁹⁰Sr. Results indicated that a 30-minute exposure to ⁹⁰Sr induced double strand breaks in DNA, followed by DNA repair, senescence and differentiation. After 7 days of exposure, MS5 cells showed a decreased ability to proliferate, changes in cytokine expression, and changes in their ability to support hematopoietic progenitor proliferation and differentiation. These results demonstrate that chronic exposure to a low concentration of ⁹⁰Sr can induce functional changes in BMSCs that in turn may explain the health effects observed in following chronic ⁹⁰Sr exposure.

Immune System Modifications Induced in a Mouse Model of Chronic Exposure to (90)Sr

Strontium 90 ((90)Sr) remains in the environment long after a major nuclear disaster occurs. As a result, populations living on contaminated land are potentially exposed to daily ingesting of low quantities of (90)Sr. The potential long-term health effects of such chronic contamination are unknown. In this study, we used a mouse model to evaluate the effects of (90)Sr ingestion on the immune system, the animals were chronically exposed to (90)Sr in drinking water at a concentration of 20 kBq/l, for a daily ingestion of 80-100 Bq/day. This resulted in a reduced number of CD19(+) B lymphocytes in the bone marrow and spleen in steady-state conditions. In contrast, the results from a vaccine experiment performed as a functional test of the immune system showed that in response to T-dependent antigens, there was a reduction in IgG specific to tetanus toxin (TT), a balanced Th1/Th2 response inducer antigen, but not to keyhole limpet hemocyanin (KLH), a strong Th2 response inducer antigen. This was accompanied by a reduction in Th1 cells in the spleen, consistent with the observed reduction in specific IgG concentration. The precise mechanisms by which (90)Sr acts on the immune system remain to be elucidated. However, our results suggest that (90)Sr ingestion may be responsible for some of the reported effects of internal contamination on the immune system in civilian populations exposed to the Chernobyl fallout.

Effect of 90Sr internal emitter on gene expression in mouse blood

Background

The radioactive isotope Strontium-90 (⁹⁰Sr) may be released as a component of fallout from nuclear accidents, or in the event of a radiological incident such as detonation of an improvised nuclear device, and if ingested poses a significant health risk to exposed individuals. In order to better understand the response to ⁹⁰Sr, using an easily attainable and standard biodosimetry sample fluid, we analyzed the global transcriptomic response of blood cells in an in vivo model system.

Results

We injected C57BL/6 mice with a solution of 90SrCl2 and followed them over a 30-day period. At days 4, 7, 9, 25 and 30, we collected blood and isolated RNA for microarray analyses. These days corresponded to target doses in a range from 1–5 Gy. We investigated changes in mRNA levels using microarrays, and changes in specific microRNA (miRNA) predicted to be involved in the response using qRT-PCR. We identified 8082 differentially expressed genes in the blood of mice exposed to ⁹⁰Sr compared with controls. Common biological functions were affected throughout the study, including apoptosis of B and T lymphocytes, and atrophy of lymphoid organs. Cellular functions such as RNA degradation and lipid metabolism were also affected during the study. The broad down regulation of genes observed in our study suggested a potential role for miRNA in gene regulation. We tested candidate miRNAs, mmu-miR-16, mmu-miR-124, mmu-miR-125 and mmu-mir-21; and found that all were induced at the earliest time point, day 4.

Conclusions

Our study is the first to report the transcriptomic response of blood cells to the internal emitter ⁹⁰Sr in mouse and a possible role for microRNA in gene regulation after ⁹⁰Sr exposure. The most dramatic effect was observed on gene expression related to B-cell development and RNA maintenance. These functions were affected by genes that were down regulated throughout the study, suggesting severely compromised antigen response, which may be a result of the deposition of the radioisotope proximal to the hematopoietic compartment in bone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1774-z) contains supplementary material, which is available to authorized users.