Y Llabador

Advantages of high speed scanning for microprobe analysis of biological samples

Abstract The damage caused by the impact of a high energy focused ion beam on biological targets can lead, in a number of cases, to erroneous analytical results. Some of the observed modifications result from cummulative radiolytic effects and cannot be avoided. However, those alterations, induced by a local increase of the sample temperature can be minimized by high speed scanning. We present here the first comparative results achieved by irradiation of organic samples by the CENBG Nuclear Microprobe for different scan frequencies.

Low plasma Chromium in patients with coronary artery and heart diseases

Plasma chromium concentrations have been determined for 150 patients. These were subjected to coronary artery cineangiography and thereby divided into three groups: group CAD (those with coronary artery disease), group HD (those with heart disease, but no CAD) and group N (those with no CAD and no HD). Weighted, average chromium levels for these groups were 1.05, 1.72, and 8.51 ng/mL, respectively. The distributions of plasma chromium levels for the three groups suggest that an upper limit for plasma chromium may be established (6 ng/mL in this work) beyond which CAD may be considered to be extremely unlikely, thus eliminating the need for a certain number of cineangiographic examinations.

Applications of nuclear microprobes in the life sciences : an efficient analytical technique for research in biology and medicine

Sample processing for microanalysis of living tissue microanalysis and cell biology advances in toxicology and trace-element biology tissue analysis and clinic study of unicellular micro-organisms and plant biology.

Selenium in foods in France

Abstract The selenium levels in various samples of French meats, fish, vegetables, fruits, and other foodstuffs have been measured using a proton-induced X-ray emission (PIXE) method. Averaged levels found in France are low compared to those reported in the United States, but are comparable to those found in other European countries.

PIXE microanalysis in human cells: physiology and pharmacology

Abstract The micro-PIXE technique has been regularly carried out for more than two years to provide elemental distributions in human cells. Using this technique in the framework of cellular biology, two research axes have been developed: the cellular pharmacology f chemotherapeutic agents and the physiology of ionic cellular exchanges. These studies are based upon in vitro experimental models of human cells, either under the form of isolated cultured cells or as part of well-structured tissues. The aim of this paper is to present the experimental procedures and methodological aspects of cellular and subcellular quantitative mapping. Cell processing, identification of intracellular structures, quantitatives results and beam damage will be discussed and illustrated by examples issuing from the above-mentioned studies.

The nuclear microprobe: An insight of applications in cell biology

During the last five years, the evolution of biomedical research based upon nuclear microprobe analysis has followed the development of experimental models of cultured or isolated cells. Fundamental studies of cellular mechanisms have been approached by means of in vitro assays associated with single cell analysis. Within those groups which are involved in such programs, special emphasis has been placed on cell culture and processing techniques which fulfill the methodological requirements for intracellular ion beam analysis. Great efforts have been orientated towards the improvement of normalization procedures. It is now possible to provide reliable quantitative results expressed in such units that they can be easily cross-checked using conventional methods. Imaging techniques have been also developed for the identification of the analyzed structures. In this paper, different domains of cell biology which have been addressed during the last years are reviewed. Studies dealing with cellular physiology and pharmacology are briefly presented as are also those related to the role of trace elements. Topics under development in our group as well as ongoing investigations will be also evoked.

High sensitivity PIXE determination of selenium in food and biological samples using a preconcentration technique

Abstract We have developed a very sensitive method to measure the selenium content in biological materials and different foods using PIXE after chemical preconcentration in the presence of tellurium. The preconcentration yield is determined using radioactive selenium, and yttrium is added as an internal standard.

Light-element analysis with the CENBG nuclear microprobe

In the field of light-element detection (Z < 11), the capability of the nuclear muprobe to carry out nuclear reaction analysis offers significant advantages compared with other methods. But taking into account the low beam current available, reactions with large cross sections must be selected in order to achieve acquisition in a reasonable time. This restriction prevents the use of RBS analysis for detection of light elements in heavy matrices. Moreover, the 8 μm beryllium window of standard X-ray detectors does not permit the PIXE measurement of light elements. We present here some examples in the use of the resonant nuclear reactions 12C(p, p)12C and 16O(α, α)16O for carbon and oxygen determination in different materials. Results are discussed in terms of strength and limit of nuclear reactions compared with new possibilities of X-ray detectors following improvements in the transmission of low energy radiation through windows.

Iron in hereditary retinal degeneration: PIXE microanalysis: Preliminary results

Abstract Several types of hereditary retinal degeneration with progressive alteration of photoreceptors exist in men and animals. Recent immunohistochemical results have shown strong degradation of transferrin, the protein responsible for iron transport, in retinas of rats with hereditary retinal degeneration. Freeze-dried thin sections of rat retinas from different stages of the disease, and respective coeval control sections, have been analyzed using nuclear microprobe. In this first part of the study, the rat retinas at post-natal stages of 35 and 45 days have been analyzed. The sample preparation and the post-irradiation staining to determine precisely the retinal layers involved are described. Preliminary results of element distributions (K, Ca, Fe) in the rat retina layers are discussed. A very high content of calcium in the choriocapillaris of dystrophic rat retinas was observed. Preliminary results on iron distribution in the rat retina layers are presented.

TRACE METAL CONTENT IN DISTINCT GENOTYPES OF HUMAN NEUROBLASTOMA CELLS : PRELIMINARY RESULTS

Abstract Some transition metals play important regulatory roles in gene expression. The disturbance of their cellular levels could be involved in oncogene expression and tumorigenesis. Nuclear Microprobe Analysis (NMPA) was used to measure cellular trace metal levels (Mn, Fe, Cu, Zn) in two human neuroblastoma cell lines characterized by distinct genotypes. In this paper, a specific protocol established for sample preparation of neuronal cultured cells is described. Trace metal concentrations in SK-N-SH and IGR-N-91 cells exhibiting respectively a single copy, and 60 copies, of the N-myc oncogene are reported. A brief discussion on experiment design for NMPA of trace metal functions in gene expression is also presented.