Ex vivo uranium decontamination efficiency on wounded skin and in vitro skin toxicity of a calixarene-loaded nanoemulsion

International audienceThe present work aims at studying the decontamination efficacy of a calixarene-loaded nanoemulsion on two ex vivo wounded skin models mimicking superficial stings or cuts contaminated with uranium, and on a third model using excoriation. The decontaminating formulation was compared with the currently used radio-decontaminating soapy water (Trait rouge®) treatment. Moreover, to assess skin damage potentially induced by the undiluted nanoemulsion, in vitro toxicity studies were conducted on an in vitro reconstructed human epidermis, coupled with three different toxicity tests [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide, lactate dehydrogenase, and interleukin-1-α]. This work demonstrated not only a significant decontamination activity of the calixarene nanoemulsion on wounded skin, ranging from 92% to 94% of the applied uranium solution according to the ex vivo model used, but also the absence of side effects of this promising treatment. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association

Intranasal exposure to uranium results in direct transfer to the brain along olfactory nerve bundles

International audienceAims Uranium olfactory uptake after intranasal exposure raises some concerns for people potentially exposed to airborne radionuclide contamination as the brain could be a direct target for these contaminants. A model of nasal instillation was used to elucidate the transport mechanisms of uranium to the brain and to map its localization. Methods Increasing concentrations of depleted uranium containing solutions were instilled in the nasal cavity of adult male rats. Uranium concentrations were measured using inductively coupled plasma-mass spectrometry (ICP-MS) 4h after instillation. Olfactory neuroepithelium cytoarchitecture was studied using immunohistochemistry experiments. Secondary ion mass spectrometry (SIMS) microscopy was performed to localize uranium in the olfactory system. Results ICP-MS analyses showed a frontal accumulation of uranium in the olfactory bulbs associated with a smaller increase in more caudal brain regions (frontal cortex, hippocampus and cerebellum). Uranium concentrations in the olfactory bulbs do not reach a saturation point. Olfactory nerve bundle integrity is not affected by uranium as revealed by immunohistochemistry. SIMS microscopy allowed us to show that uranium localization is mainly restricted to the olfactory neuroepithelium and around olfactory nerve bundles. It is subsequently detected in the olfactory nerve layer of the olfactory bulb. Discussion These results suggest the existence of a transcellular passage from the mucosa to the perineural space around axon bundles. Uranium bypasses the blood brain barrier and is conveyed to the brain via the cerebrospinal fluid along the olfactory nerve. Future studies might need to integrate this new contamination route to assess uranium neurotoxicity after nasal exposure. © 2013 British Neuropathological Society

Detection and analysis of the microdistribution of uranium in the gills of freshwater Corbicula fluminea by SIMS technique

The microdistribution of uranium in the gills of freshwater bivalve Corbicula fluminea following chronic direct exposure to this radioelement has been investigated using the SIMS technique. Different exposure levels and exposure durations have been studied. The SIMS mass spectra and 238U+ ion images produced with a SIMS CAMECA 4F-E7 show an U accumulation with the lower aqueous U concentration (20 μg/L) and the influence of the exposure levels on the bioaccumulation capacities. Furthermore, the ionic images display a heterogeneous distribution of uranium within the gill structure whatever the exposure conditions are. This study, in keeping with the ENVIRHOM French research program, was led to the conclusion that ion microscopy is an appropriate analytical method for trace elements and can give elemental cartography in a biological tissue section. © 2009 Elsevier B.V. All rights reserved

Compared in vivo efficiency of nanoemulsions unloaded and loaded with calixarene and soapy water in the treatment of superficial wounds contaminated by uranium

International audienceNo emergency decontamination treatment is currently available in the case of radiological skin contamination by uranium compounds. First responders in the workplace or during an industrial nuclear accident must be able to treat internal contamination through skin. For this purpose, a calixarene nanoemulsion was developed for the treatment of intact skin or superficial wounds contaminated by uranium, and the decontamination efficiency of this nanoemulsion was investigated in vitro and ex vivo. The present work addresses the in vivo decontamination efficiency of this nanoemulsion, using a rat model. This efficiency is compared to the radio-decontaminant soapy water currently used in France (Trait rouge®) in the workplace. The results showed that both calixarene-loaded nanoemulsion and non-loaded nanoemulsion allowed a significant decontamination efficiency compared to the treatment with soapy water. Early application of the nanoemulsions on contaminated excoriated rat skin allowed decreasing the uranium content by around 85% in femurs, 95% in kidneys and 93% in urines. For skin wounded by microneedles, mimicking wounds by microstings, nanoemulsions allowed approximately a 94% decrease in the uranium retention in kidneys. However, specific chelation of uranium by calixarene molecules within the nanoemulsion was not statistically significant, probably because of the limited calixarene-to-uranium molar ratio in these experiment conditions. Moreover, these studies showed that the soapy water treatment potentiates the transcutaneous passage of uranium, thus making it bioavailable, in particular when the skin is superficially wounded. © 2016 Elsevier Ireland Lt

Intracellular uranium distribution : Comparison of cryogenic fixation versus chemical fixation methods for SIMS analysis

International audienceLocalization of uranium within cells is mandatory for the comprehension of its cellular mechanism of toxicity. Secondary Ion Mass Spectrometry (SIMS) has recently shown its interest to detect and localize uranium at very low levels within the cells. This technique requires a specific sample preparation similar to the one used for Transmission Electronic Microscopy, achieved by implementing different chemical treatments to preserve as much as possible the living configuration uranium distribution into the observed sample. This study aims to compare the bioaccumulation sites of uranium within liver or kidney cells after chemical fixation and cryomethods preparations of the samples SIMS analysis of theses samples show the localization of uranium soluble forms in the cell cytoplasm and nucleus with a more homogenous distribution when using cryopreparation probably due to the diffusible portion of uranium inside the cytoplasm. © 2018 The Authors. Microscopy Research and Technique Published by Wiley Periodicals, Inc

Chronic uranium exposure dose-dependently induces glutathione in rats without any nephrotoxicity

International audienceUranium is a heavy metal naturally found in the earth's crust that can contaminate the general public population when ingested. The acute effect and notably the uranium nephrotoxicity are well known but knowledge about the effect of chronic uranium exposure is less clear. In a dose-response study we sought to determine if a chronic exposure to uranium is toxic to the kidneys and the liver, and what the anti-oxidative system plays in these effects. Rats were contaminated for 3 or 9 months by uranium in drinking water at different concentrations (0, 1, 40, 120, 400, or 600 mg/L). Uranium tissue content in the liver, kidneys, and bones was linear and proportional to uranium intake after 3 and 9 months of contamination; it reached 6 μg per gram of kidney tissues for the highest uranium level in drinking water. Nevertheless, no histological lesions of the kidney were observed, nor any modification of kidney biomarkers such as creatinine or KIM-1. After 9 months of contamination at and above the 120-mg/L concentration of uranium, lipid peroxidation levels decreased in plasma, liver, and kidneys. Glutathione concentration increased in the liver for the 600-mg/L group, in the kidney it increased dose dependently, up to 10-fold, after 9 months of contamination. Conversely, chronic uranium exposure irregularly modified gene expression of antioxidant enzymes and activities in the liver and kidneys. In conclusion, chronic uranium exposure did not induce nephrotoxic effects under our experimental conditions, but instead reinforced the antioxidant system, especially by increasing glutathione levels in the kidneys

First Report of <i>Tomato chlorotic dwarf viroid</i> in Tomato in France

Tomato chlorotic dwarf viroid (TCDVd) is a pospiviroid found naturally infecting tomato (Solanum lycopersicum L.) (3) and several ornamentals such as Brugmansia, petunia (1), and trailing verbena (4). Initially identified in North America (3), it has been reported from India, Europe (the Netherlands and United Kingdom), and Japan. At the end of 2007, 20 to 25% of tomato plants within a group of greenhouses in the Brittany Region of France were observed with top bunching, leaf curling, and epinasty symptoms. Reverse transcription (RT)-PCR with a primer pair specific for several pospiviroids (5′GGGGAAACCTGGAGCGA3′ and 5′GGGGATCCCTGAAGCGC3′) amplified the correctly sized fragment (approximately 360 bp) from total nucleic acid extracts from three symptomatic plants. The sequence of the uncloned amplification product (GenBank Accession No. EU729744) was determined, together with that of five cloned cDNAs. All sequences were highly related with a total of three mutations in these six sequences and they showed 96.9% (GQ169709 and AY372399) to 99.4% (AF162131) identity with TCDVd sequences present in GenBank. Identification of TCDVd was confirmed from the same plant samples by molecular hybridization with a Potato spindle tuber viroid (PSTVd)-specific probe (which cross-hybridizes with TCDVd to a certain extent) and by PCR with the PSTVd/TCDVd-specific 2A-1S primer pair (3) and sequencing of the amplified fragment. The French isolate is most closely related to the original tomato isolate from Canada (GenBank Accession No. AF162131). In a grow-out test involving 2,500 seeds from the original seed lot from which the symptomatic plants were derived, 2 of the 250 pools of 10 plants tested positive for TCDVd infection with the 3H1-2H1 primer pair (2). The sequence of the amplified product proved identical to the isolate detected in the original greenhouse plants, indicating a low level of seed transmission. As with other pospiviroids, which appear to be more and more frequently reported in greenhouse tomatoes, possible sources of infection include contaminated seeds, as seem to be the case in this first outbreak, and also transfer to tomatoes from infected ornamental hosts. This is, to the best of our knowledge, the first report of TCDVd in tomato in France. References: (1) T. James et al. Plant Pathol. 57:400, 2008. (2) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997. (3) R. P. Singh et al. J. Gen. Virol. 80:2823, 1999. 4) R. P. Singh et al. Plant Dis. 90:1457, 2006. </jats:p

Ex vivo decrease in uranium diffusion through intact and excoriated pig ear skin by a calixarene nanoemulsion

Cutaneous contamination by radionuclides is a major concern in the nuclear industry. In case of skin exposure to uranium, no efficient emergency treatment is available to remove the actinide from the skin. For this purpose, we developed a nanoemulsion containing calixarene molecules displaying good chelating properties towards uranium. In this paper, we describe the ability of this formulation to trap uranium and limit its transfer from the cutaneous contaminated site into the blood. Uranium percutaneous diffusion kinetics was assessed with Franz cells over 24 h through intact and excoriated pig ear skin biopsies, after or without application of the nanoemulsion. Uranium distribution in the skin layers was analysed by SIMS microscopy. The results showed that prompt application of the calixarene nanoemulsion allows a 94% and 98% reduction of the amount of uranium diffused respectively through intact and excoriated skin. The formulation is still efficient in case of delayed application up to 30 minutes since the 24 h-uranium transfer through excoriated skin is reduced by 71%. Besides, no accumulation of uranium or uranium- calixarene chelate was observed in the different skin layers. In conclusion, this study demonstrated the efficiency of the calixarene nanoemulsion, which can be regarded as a promising treatment for uranium cutaneous contamination. © 2011 Elsevier B.V