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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.

The secondary ion mass spectrometry (SIMS) microscope has opened new fields in biological investigation because of its ability to map chemical elements that are either naturally present in tissue or introduced for diagnostic or therapeutic purposes. In this review, we will describe our attempts to localise and quantify antitumor drugs in histological sections to better evaluate successful early cancer treatment. Detection is dependent on the presence of chemical elements in the drug structure, for example halogens (F, Br, I, At) which are imaged and quantified within the nuclei. Our methodological approach combines the results obtained with ionic and photonic microscopes on serial sections. Thus, the different structures in tumor tissue (blood vessels and cells) can be identified and drug localisation visualized. Using embedded samples, we demonstrate that both fluorine (19F) in 5-Fluorouracil and iodine (127I) in 4'-iododeoxyrubicin can be mapped in human biopsy material obtained after in vivo chemotherapy.

Serious difficulties are encountered when SIMS analysis is applied to plant cells because of the cells' basic organization. In most plant cells, the cytoplasm is present as a thin layer that surrounds a large central vacuole, and is surrounded externally by a porous semi-rigid cell wall. Due to the high internal hydrostatic pressure typical of plant cells, large-scale solute redistribution may occur when tissues are excised. Relatively small solute decompartmentation is sufficient to collapse the native solute gradients between the cytoplasm and the adjacent compartments, due to the small volume of the former. For these reasons, most of the SIMS analyses in plant cells have been performed on elements bound to non-diffusible structures such as proteins, cell wall polymers, or in dry seeds. Sample preparation remains a limiting factor when imaging the distribution of soluble compounds. Cryotechniques have generated considerable interest to circumvent these problems. Cryofixation followed by cryosectioning would a priori be the best procedure, but encouraging results indicate that cryofixation followed by cryosubstitution is an interesting alternative.

We measured the 127I distribution within tyroid tissue to find out where intrathyroid iodine was deposited during iodine treatment in eight Tunisian female patients (aged 33-58 yr) with endemic euthyroid goiter. Before surgery, five patients were treated during 6 months either by Lugol's solution (group 1: three patients) or by Lugol's and L-thyroxine (group 2: two patients). All patients remained euthyroid during the course of the treatment, which supplied 3.8 mg/day iodine. Three other patients did not receive Lugol's solution (control group). Secondary ion mass spectrometry microscopy was used to map 127-I quantitatively on thyroid sections. Specimens obtained at thyroid surgery were divided macroscopically into nodular and extranodular tissue and chemically fixed to preserve organified iodine. The iodine profile of patients in group 1 did not differ from that in group 2: large amounts of iodine were localized in thyroid follicles and stroma of both nodular and extranodular tissues. In the control group, iodine within stroma was found only in the extranodular tissue. Despite the limited number of patients studied, these data suggest that stromal iodine might represent a storage compartment in times of large iodine supply.

The subcellular distribution of halogenous molecules has been studied by SIMS microscopy in cultured cells of a human breast carcinoma (MCF-7 cell line). Two instruments of microanalysis were used. A low lateral resolution ion microscope (SMI 300 CAMECA) and a prototype scanning ion microscope equipped with a cesium gun that gives high lateral resolution images. This apparatus has been developed by G Slodzian, in Onera Laboratories (Office National d'Etudes et de Recherches Aerospatiales). Molecules studied by low lateral resolution ion microscope were halogenous steroids: fluorometholone, triamcinolone, bromocriptine and bromoandrosterone. Analytical images show that the first two compounds are mainly localized in the nuclear structure of MCF-7 cells whereas the last two molecules are localized in cytoplasm of these cells. Images were obtained with a resolution of 1 μm. With the scanning ion microscope, it is now possible to obtain images at the ultrastructural level. Four analytical images can be simultaneously obtained by a single scan of the imaged area, corresponding to a depth of erosion of the section of ten nm. The intranuclear distributions of three pyrimidine analogs, 5-bromo-2′-deoxyuridine, 5-iodo-2′-deoxyuridine and 5-fluorouracil have been studied in phase S and M of MCF-7 cells and these images have been compared to the distribution of sulfur, nitrogen and phosphorus. All these images have been obtained with a lateral resolution better that 100 nm.

We attempted to indicate the requirements for biomedical applications of SIMS microscopy. Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue. Furthermore, it is often necessary to correlate ionic and light microscope images. This implies a common methodological approach to sample preparation for both microscopes. The use of low or high mass resolution depends on the elements studied and their concentrations. To improve the acquisition and processing of images, digital imaging systems have to be designed and require both ionic and optical image superimposition. However, the images do not accurately reflect element concentration; a relative quantitative approach is possible by measuring secondary ion beam intensity. Using an internal reference element (carbon) and standard curves the results are expressed in micrograms/mg of tissue. Despite their limited lateral resolution (0.5 microns) the actual SIMS microscopes are very suitable for the resolution of biomedical problems posed by action modes and drug localization in human pathology. SIMS microscopy should provide a new tool for metabolic radiotherapy by facilitating dose evaluation. The advent of high lateral resolution SIMS imaging (less than 0.1 microns) should open up new fields in biomedical investigation.

We defined the SIMS conditions for radioiodine detection in animal and man thyroid follicles, in tissue sections (3 μm) chemically fixed and resin embedded. Two radioisotopes were tested: 125I and 129I, of high (14 mCi 125I μg−1) and low specific activity (1.07 10−6 mCi 129I μg−1). In animal study, Wistar rats fed a normal iodine diet (10 μg 127I day−1) were injected ip 24 h before sacrifice either with 125I (7 10−3 μg) or with 129I at a dose identical to iodine diet (10 μg) or 3 times higher (30 μg). No SIMS signal of 125I was obtained in vivo due to its too low concentration, while radioiodine distribution was evidenced with both doses of 129I. Local concentration of previously stored 127I in follicular lumen was not modified, when compared to control (4.14 ± 0.03 μg/mg, m ± SE), by 125I or 129I at a dose of 10 μg, but was nearly doubled with 129I at a dose of 30 μg, proof of a pharmacological effect on thyroid iodine regulation. In human study 129I was excluded due to its long half-life (1.6 107 years), and 125I was tested only in vitro on two surgical specimens of normal perinodular thyroid tissue maintained in mini-organ culture for 48 h in presence of 100 μCi/ml of 125I. The 125I was detectable, its concentration was 1000-fold higher than that of 127I (1.5 ± 0.004 μg/mg). For both in vivo and in vitro studies, a positive correlation exists between newly organified radioiodine (125I or 129I) and previously stored iodine (127I). In conclusion, the radioisotope 129I used at a dose of 10 μg is well adapted for SIMS detection in vivo of thyroid exchangeable iodine, but only in animal, while 125I isotope is especially adapted for in vitro study in man.

The distribution of 15N and 14N compounds in cryofixed and resin embedded sections of soybean (Glycine max L) leaves was studied by SIMS microscopy. The results indicate that, with a mass resolution M/ΔM higher than 6000, images of the nitrogen distribution can be obtained from the mapping of the two secondary cluster ions 12C14N− and 12C15N−, in samples of both control and 15N-labeled leaves. The ionic images were clearly related to the histological structure of the organ, and allow the detection of 14N and 15N at the subcellular level. Furthermore, relative measurements of the 12C14N− and 12C15N− beams made possible the quantification of the 15N atom% in the various tissues of the leaf.

Background Analytical imaging by secondary ion mass spectrometry (SIMS) provides images representative of the distribution of a specific ion within a sample surface. For the last fifteen years, concerted collaborative research to design a new ion microprobe with high technical standards in both mass and lateral resolution as well as in sensitivity has led to the CAMECA NanoSims 50, recently introduced onto the market. This instrument has decisive capabilities, which allow biological applications of SIMS microscopy at a level previously inaccessible. Its potential is illustrated here by the demonstration of the specific affinity of a melanoma marker for melanin. This finding is of great importance for the diagnosis and/or treatment of malignant melanoma, a tumour whose worldwide incidence is continuously growing. Methods The characteristics of the instrument are briefly described and an example of application is given. This example deals with the intracellular localization of an iodo-benzamide used as a diagnostic tool for the scintigraphic detection of melanic cells (e.g. metastasis of malignant melanoma). B16 melanoma cells were injected intravenously to C57BL6/J1/co mice. Multiple B16 melanoma colonies developed in the lungs of treated animals within three weeks. Iodobenzamide was injected intravenously in tumour bearing mice six hours before sacrifice. Small pieces of lung were prepared for SIMS analysis. Results Mouse lung B16 melanoma colonies were observed with high lateral resolution. Cyanide ions gave "histological" images of the cell, representative of the distribution of C and N containing molecules (e.g. proteins, nucleic acids, melanin, etc.) while phosphorus ions are mainly produced by nucleic acids. Iodine was detected only in melanosomes, confirming the specific affinity of the drug for melanin. No drug was found in normal lung tissue. Conclusion This study demonstrates the potential of SIMS microscopy, which allows the study of ultra structural distribution of a drug within a cell. On the basis of our observations, drug internalization via membrane sigma receptors can be excluded.

The notion of diffusible ions is reviewed in the light of recent knowledge on the stage of water in biological matrices. It appears that ion distributions would be little affected as long as water-macromolecular equilibrium is maintained, but they risk to be significantly modified during dehydration, because the transformation of bound water into highly solvating free water can produce ion displacements. In addition, differently hydrated areas may undergo unequal volume variations. The principal modes of preparing material for SIMS (secondary ion mass spectrometry) microscopy are envisaged from this viewpoint.

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.