Radiation Induced X-ray Emission Research Articles

Analysis of synchrotron radiation induced X-ray emission spectra with R environment

Life sciences have seen a huge increase in the amount and complexity of data being collected with every experiment. Scientists today are faced with increasingly difficult task to extract vital information from the vast amount of numbers. Software used for this purpose should be sufficiently powerful and flexible to handle large and complex data sets. On the other hand it should allow the user to exactly follow what is being calculated, black-box type of software should be avoided. R platform (R Development Core Team, 2011), open-source environment for statistical analysis nicely fits these requirements. With its rapidly expanding user community it is quickly becoming the most important tool in statistical analysis of data in broad range of applications. The most important feature of R is the package system, allowing users to address specific problems with dedicated package and even for more advanced users to contribute software for their own fields. In this paper multivariate analysis and data treatment of spectral data by using R environment is presented.

Synchrotron radiation induced X-ray emission studies of the antioxidant mechanism of the organoselenium drug ebselen

Synchrotron radiation induced X-ray emission (SRIXE) spectroscopy was used to map the cellular uptake of the organoselenium-based antioxidant drug ebselen using differentiated ND15 cells as a neuronal model. The cellular SRIXE spectra, acquired using a hard X-ray microprobe beam (12.8-keV), showed a large enhancement of fluorescence at the K(α) line for Se (11.2-keV) following treatment with ebselen (10 μM) at time periods from 60 to 240 min. Drug uptake was quantified and ebselen was shown to induce time-dependent changes in cellular elemental content that were characteristic of oxidative stress with the efflux of K, Cl, and Ca species. The SRIXE cellular Se distribution map revealed that ebselen was predominantly localized to a discreet region of the cell which, by comparison with the K and P elemental maps, is postulated to correspond to the endoplasmic reticulum. On the basis of these findings, it is hypothesized that a major outcome of ebselen redox catalysis is the induction of cellular stress. A mechanism of action of ebselen is proposed that involves the cell responding to drug-induced stress by increasing the expression of antioxidant genes. This hypothesis is supported by the observation that ebselen also regulated the homeostasis of the transition metals Mn, Cu, Fe, and Zn, with increases in transition metal uptake paralleling known induction times for the expression of antioxidant metalloenzymes.

Using micro-synchrotron radiation induced X-ray emission distribution maps to determine correlation between elements in prostate tissue

Elemental maps obtained by micro-synchrotron radiation induced X-ray emission technique can be manipulated in several ways to extract useful information. In this paper the method of displaying the correlation between two or three elements in one correlation map is described. Such types of maps give precise information about the overlap between the elements without distorting the original data. In micro-synchrotron radiation induced X-ray emission experiments, the results are often presented as a set of elemental maps, one map for each element of interest per measurement. However, interpreting such a set of maps is not always trivial, especially for the correlation of elements in complicated structures. Refinement of the technique called “two-values” map by assigning one color for each element is presented here. The intensity of the color corresponds to the elemental amount in the map. These one color maps can be combined to provide correlation maps. If two or more elements are present in the same pixel, the resulting color of the pixel is a blend of the primary colors (e.g. yellow if green and red pixels are combined). Our implementation is based on the red, green, and blue color scheme so that two or three elemental maps can be combined. To obtain a color in the red, green, and blue system, three values between 0 (black) and 255 (full intensity) for, respectively, red, green, and blue are needed.

Transport kinetics of four- and six-coordinate platinum compounds in the multicell layer tumour model

Four-coordinate (Pt(II)) platinum-based anticancer drugs are widely used in primary or palliative chemotherapy and produce considerable efficacy in certain clinical applications, for example testicular cancer. However, in many cancers the Pt(II) drugs are beset by poor efficacy mainly due to suboptimal pharmacokinetic properties. Consequently, the six-coordinate (Pt(IV)) class of Pt drugs were developed to improve platinum efficacy by (i) increasing stability, (ii) reducing reactivity, (iii) increasing lipophilicity, and (iv) nuclear targeting. However, comparatively little information is available on the pharmacokinetic properties of these compounds within solid tumour tissue. In the present study, the distribution and fluxes of [14C]-labelled [PtCl2(en)] (where en stands for ethane-1,2-diamine) and cis,trans-[PtCl2(OH)2(en)] drugs were determined in the multicell layer (MCL) tumour model comprising colon cancer cells. Flux data were analysed by mathematical modelling of drug diffusion and cellular uptake in the transport system. The flux of the Pt(IV) compound through the MCL was not significantly different to that of the Pt(II) drug nor were the diffusion coefficient or tissue uptake; the latter confirmed with elemental imaging analysis by synchrotron radiation induced X-ray emission. However, the flux of the Pt(IV) through the MCL was increased by hydrostatic pressure, thereby demonstrating the potential to target cancer cells further away from the vessels with six-coordinate platinum drugs.

The application of synchrotron radiation induced X-ray emission in the measurement of zinc and lead in Wistar rat ameloblasts

The development of analytical techniques for the measurement of trace elements in cellular compartments of developing teeth remains an important methodological issue in dental research. Recent advances in third generation synchrotron facilities have provided high brilliance X-ray sources that can be effectively used to study trace element distributions in small spatial regions with low detection limits. The present study describes for the first time the application of synchrotron radiation induced X-ray emission (SRIXE) in measuring the distribution of zinc and lead in the ameloblasts of developing Wistar rat teeth. Wistar rats were fed a standard rat diet, containing the normal dietary requirements of zinc, ad libitum and exposed to 100 ppm of lead in drinking water. Resin embedded sections of first mandibular molars were analysed using a 13.3 keV incident monochromatic X-ray beam focussed to a 0.2 μm spot. Characteristic X-rays arising from the entire thickness of the sample were measured using an energy dispersive detector for quantitative analysis of elemental concentrations. The results showed that intranuclear concentrations of zinc were greater than levels in the cytoplasm. Furthermore, nuclear and cytoplasmic concentrations of zinc in the maturation stage (742 ± 27 and 424 ± 25 ppm, respectively) were significantly higher than the zinc levels observed in the nucleus and cytoplasm of presecretory stage ameloblasts (132 ± 10 and 109 ± 10 ppm, respectively) ( p < 0.05). A clear lead signal above the background was not detected in the ameloblasts and lead concentrations could only be reliably measured in the developing enamel. Overall, SRIXE was an effective method of studying the spatial distribution of zinc in the cells of developing teeth and offered a unique combination of sub-micron spatial resolution and parts-per-million detection limits (0.8–1 and 0.6–1 ppm for zinc and lead, respectively).

Risk assessment of TiO 2 photocatalyst by individual micrometer-size particle analysis with on-site combination of SEM-EDX and SR-XANES microscope

Applications of synchrotron radiation X-ray fluorescence (SR-XRF) microscopy combined with scanning electron microscopy (SEM) are reported. Electron beam excited and synchrotron radiation induced X-ray emission spectra of the same yellow sand single particles are reported and compared. The Ti-K edge absorption fine structure of single microparticles of TiO 2 (rutile, anatase, and a photocatalyst aerosol) are recorded by using monochromatic synchrotron radiation of tunable energy. It is shown that the discrimination between rutile and anatase is possible. Based on the single particle speciation, the toxicity of photocatalyst aerosol powder is discussed.

Preliminary Study on Chemical Speciation of Sulphur in Cancerous Tissues

Sulphur is vital for almost all living organisms by participating in a wide variety of metabolic processes. Nevertheless its biochemistry is only partially understood, due to it a few tools such as X-ray absorption near edge structure may be used to determine its chemical speciation in biological system. In this paper we focused on analysis of composition and elemental distribution in tissue structures of biological samples. We examined cancerous and noncancerous prostate tissues. Experiments were carried out on the L-beam line at the HASYLAB, DESY (Hamburg, Germany) and DAΦNE-Light Facility DRX1 at the Laboratori Nationali di Frascati (Frascati, Italy). Synchrotron radiation induced X-ray emission measurements reveal the significant differences in concentration of sulphur between cancerous and non-cancerous tissues. X-ray absorption near edge structure spectra show two main types of sulphur that are represented by X-ray peaks at 2476 eV and 2484 eV. This suggests that different sulphur components are present in the measured samples.

Cancerous tissues analyzed by SRIXE

Synchrotron radiation induced X-ray emission (SRIXE) analysis of trace element (TE) concentrations in prostate tissues shows the significant differences between elemental concentrations in cancer and healthy parts of tissues. The analysis enables obtaining additional information about the prostate cancer, almost the most dangerous disease of the recent days. The cancer tissue sections were obtained after radical removal of the organ from the patient's body. The samples were histologically examined and classified as well as the Gleason score was determined. After histological examination, the samples were irradiated with monochromatic X-ray beam at the beam line L at HASYLAB in DESY. Our investigation proved that the elements such as Mn, Fe, Co, Ni which are involved in cancerogenesis appeared on elevated concentration levels in cancerous part of the tissues in comparison to non-cancerous parts. This study may also indicate that the advancement of prostate cancer is connected with the content of copper, zinc and iron.

Iron and other elements studies in cancerous and non-cancerous prostate tissues

To understand the role of trace elements in the oxidative stress, which may be an important factor in the pathogenesis of prostate cancer, we investigated the distribution and chemical state of Fe using synchrotron radiation. Therefore, both synchrotron radiation induced X-ray emission (SRIXE) and X-ray absorption near-edge structure (XANES) techniques have been applied to study cancerous and non-cancerous prostate tissues. The results obtained in this work prove that SRIXE and XANES techniques are complementary ones for analysis of trace elements in biomedical samples. The absorption K-edge position of iron determined in cancerous tissue is shifted by 2.9 eV towards higher energies in comparison to iron absorption K-edge determined in non-cancerous tissue. The information obtained in this way may help to understand the role of oxidation state of iron in the oxidative stress underlying the oncogenesis.

Trace elements distribution in renal cell carcinoma depending on stage of disease.

The aim of this study was to identify those trace elements which can be used to distinguish between normal and malignant tissue in renal cell cancer (RCC) kidney and to assess changes in trace elements concentration in tissue with progressing malignant disease. In case control study, 36 cases of RCC were analyzed by Synchrotron Radiation Induced X-ray Emission (SRIXE) in order to establish the concentration of 19 elements. Patients with RCC were examined to obtain staging of disease after radical nephrectomy, which was performed in each case. Results were compared with 15 control kidney cortex tissue obtained during autopsy in which cause of death was trauma. The most relevant decrease was detected in Cd content: from 81 +/- 39.2 ppm in normal control samples to 16.6 +/- 22.2 ppm concentration in RCC. We found that the concentrations of Ti, Pb and Rb were also lower in RCC tissue. On the other hand, the RCC tissue was rich in iron and zirconium. With the progress of malignant disease, assessed by TNM (UICC 1997) scale, lower concentration of S and higher concentration of Ca in both RCC and neoplastic kidney cortex can be seen. The same tendency is observed in Zn and Se concentrations. Cadmium shows raising concentration with progress of RCC only in cortex of neoplastic kidney. In all cases it was shown that the relatively high tissue concentration of iron in both investigated tissues is decreasing with the progress of disease. The zirconium has shown raising tissue concentration in advanced disease. Trace elements concentration is different in malignant tissue and surrounding macroscopically unchanged kidney cortex. Progress of the disease is connected with changes in trace elements concentration. This may reflect different biology of compared tissue with potential practical implication.

Preliminary study on the distribution of selected elements in cancerous and non-cancerous kidney tissues

In this study special interest was given to trace elements recognized as to be carcinogenic to humans. The kidney tissue sections were analyzed in order to determine the concentrations of elements present in the sample. The Synchrotron Radiation Induced X-ray Emission (SRIXE) technique was applied using a white photon microbeam. The results from cancerous parts of the kidney tissues were compared to non-cancerous parts and to the control group. In addition the iron concentration level was determined in the serum of those patients. Two-dimensional scans are presented to illustrate the differences between perfused and not-perfused tissues. According to this study there is no significant difference in the Mn concentration between cancerous and non-cancerous parts of the kidney, but the concentrations of Cd, Cr, Ti, V, Cu, Se, and Zn are at a lower concentration level in the cancerous parts than in the non-cancerous parts. A converse observation has been made for Fe. This may be associated with different metabolism and dynamics of the cancer process and both higher vascularization and need of higher blood supply in the cancerous tissue. The two-dimensional scanning of thin kidney sections showed differences in the trace element distributions depending on the analyzed samples: perfused and non-perfused. Perfusion removed blood mostly from the peritubular capillaries while in the glomerulus some capillaries had a relatively high Fe content. A low Fe concentration was observed in nephron tubules while a converse observation has been made for Cd. This may indicate that Cd is localized in the cells but not in the blood.

Trace element analysis by means of synchrotron radiation, XRF, and PIXE: selection of sample preparation procedure

When it comes to biological samples, trace element (TE) determination has to cope with very low concentrations, sometimes even below the minimum detectable limit (MDL). This is why special sample preparation procedures have to be employed so that the TE concentration in the specimen is effectively enhanced in a known way. The aim of this study was the selection of a proper sample preparation procedure by determination of selected element concentrations in different types of biological samples. In this work several sample preparation procedures were applied in order to choose the best one for specific experimental needs. The methods included: (a) tissue sectioning method (if appropriate); (b) dry method without chemical treatment — the samples were dried, homogenized and pressed into pellet; (c) wet method with chemical treatment — the samples were mineralized. The analyses were performed with different analytical methods in order to confirm the results obtained and in order to determine the influence of target preparation procedure on the level of elemental concentrations determination. The measurements were done by means of SRIXE (synchrotron radiation induced X-ray emission), EDXRF (energy dispersive X-ray fluorescence), TR-XRF (total reflection X-ray fluorescence), and PIXE (proton-induced X-ray emission). The above methods are described and the analytical results discussed. The results of the elemental analyses performed with different techniques show a good agreement only for some elements. The mineralization process increases the sensitivity of elemental determination only for selected elements. In other cases one could observe decreasing of elemental concentration in respect to non mineralized samples. Selection of sample preparation procedure depends on analytical requirements.

Trace element analysis of tissue section by means of synchrotron radiation: the use of GNUPLOT for SRIXE spectra analysis

Synchrotron Radiation Induced X-ray Emission (SRIXE) is a powerful technique for Trace Element (TE) analysis in biomedical samples. Recently, SRIXE technique has been applied to TE determination in 20 μm thick kidney and prostate tissue sections, taken from cancerous and healthy organs. Results obtained for the latter two are compared. Matrices of biomedical samples are mostly composed of low-Z elements, and trace elements are at low levels. This is why SRIXE data analysis in such materials may be quite a challenge. In order to solve analytical problems, sophisticated fitting procedures have to be applied since a proper spectra analysis requires additional information about the sample. This is usually carried out by dedicated computer software. We are showing that satisfactory results can be obtained by employing GNUPLOT, a public domain script-driven engine for data visualization and curve fitting. The results of GNUPLOT are compared with ones obtained from QXAS, an open domain software (obtained from IAEA).

Analysis of human cancer prostate tissues using FTIR microspectroscopy and SRIXE techniques

It is known that Fourier transform infrared (FTIR) spectra of human tissues are specific and can be used to discriminate between various disease states. In this study, cancer and healthy parts of prostate tissues were examined. The human prostate tissues were obtained during surgical operation. Sections of samples were mounted onto Mylar foils and measured by both FTIR microspectroscopy and synchrotron radiation induced X-ray emission (SRIXE) methods. Neighboring sections of tissues analyzed by FTIR and SRIXE were also examined by a histopathologist. Since the SRIXE technique is suitable for trace element analysis the two-dimensional scans on both cancerous and non-cancerous parts of the prostate tissues were done in order to find elemental distribution of trace elements. The single point analysis on selected areas were also performed. Then the same samples were studied in the mid infrared region on Excalibur spectrometer with infrared microscope UMA-500 equipped with an automatic xy-stage and video camera. Both FTIR spectra and elemental distribution show differences between cancerous and non-cancerous parts of the analyzed tissues.

Articular cartilage repair in rabbits by using suspensions of allogenic chondrocytes in alginate

The feasibility of allogenic implants of chondrocytes in alginate gels was tested for the reconstruction in vivo of artificially full-thickness-damaged articular rabbit cartilage.The suspensions of chondrocytes in alginate were gelled by the addition of calcium chloride solution directly into the defects giving in situ a construct perfectly inserted and adherent to the subchondral bone and to the walls of intact cartilage. The tissue repair was controlled at 1, 2, 4 and 6 months after the implant by NMR microscopy, synchrotron radiation induced X-ray emission to map the sulfur of glycosaminoglycans and by histochemistry. Practically a complete repair of the defect was observed 4–6 months from the implant of the chondrocytes with the recovery of a normal tissue structure. Controls in which Ca-alginate alone was implanted developed only a fibrous cartilage.

Zinc mapping in bone tissues by histochemistry and synchrotron radiation–induced x-ray emission: correlation with the distribution of alkaline phosphatase

Zinc distribution in osteons was mapped by synchrotron radiation-induced X-ray emission analysis in both human and porcine adult bone, as well as in porcine bone by histochemistry using Timm’s method. Both procedures showed that zinc is not uniformly distributed, being in its highest concentration on haversian bone surfaces. When Timm’s method was applied in conjunction with a procedure leading to partial zinc extraction, three zinc pools were specifically detected: a loose one, found in the mineralizable osteoid; a mineral one, bound to the bone mineral; and a tenacious one, firmly bound to an organic component located in the osteoid and mineralizing organic matrix. The alkaline phosphatase distribution was also mapped in porcine adult bone by histochemistry and immunohistochemistry and it was found codistributed with tenacious zinc mainly at the calcification front. The data suggest that alkaline phosphatase is buried as a bone matrix protein during initial mineralization.

The spatial distribution of calcium in alginate gel beads analysed by synchrotron-radiation induced X-ray emission (SRIXE)

The spatial distribution of calcium ions in alginate gel spheres was investigated by synchrotron radiation induced X-ray emission. X-ray emission spectra were obtained from 1 mm spherical calcium alginate beads gelled either in the presence or in the absence of sodium ions. Evidence was found for an inhomogeneous distribution of calcium ions with the highest concentration at the surface, and the lowest concentration in the core of the spheres, which reflected the spatial distribution of alginate in the gel spheres. The form and the steepness of the calcium concentration gradient was strongly affected by the presence of sodium ions. © 1997 Elsevier Science Ltd.

Investigation of trace elements in cancer kidney tissues by SRIXE and PIXE

In November 1994 we performed some preliminary studies on cancer kidney tissues. The objective of the measurements was to find a difference in trace element concentrations between normal and cancerous kidney tissue. All targets were prepared as pellets of more or less the same weight and thickness. Kidney samples were obtained during surgical operations done in the Clinic of Urology in Cracow. All kidneys were subject to removal due to cancer disease. Samples for analysis were taken from the cancerous part of the kidney and the non-cancerous one. All samples were analyzed by means of SRIXE (Synchrotron Radiation Induced X-ray Emission) at the NSLS (National Synchrotron Light Source) in BNL (Brookhaven National Laboratory) and by means of PIXE at INP (Institute of Nuclear Physics) in Cracow. According to the physician's investigations, cadmium plays a role in oxidation process during tumor growth. Also the other elements i.e. selenium plays here a significant role. The results obtained so far seem to be interesting and may confirm our hypothesis about the cancer process in the kidney, the hypothesis will be a subject of further study. The applied analytical technique enables us to analyze with high precision even a small region of samples.

Corrosion phenomena in electron, proton and synchrotron X-ray microprobe analysis of Roman glass from Qumran, Jordan

A series of 89 glass fragments of Roman glass are studied using electron, proton and synchrotron radiation induced X-ray emission from microscopic areas on the sample surface. The glass originates from Qumran, Jordan and was buried for 1900 years. The weathering layers that result from the extended contact with ground water have been studied, next to the trace composition of the original glass of these pieces. The latter information indicates that at Qumran, large quantities of glass objects were being used in Ancient times. Cross-sectional profiles of the glass show a complex migration behaviour of various groups of major and trace elements.

Micro PIXE and micro SXRF: comparison of the two methods and application to glass inclusions from Vulcano (Eolian Islands — Italy)

PIXE with a 2.5 MeV proton beam of 10 × 10 μm 2 beam size and Synchrotron Radiation Induced X-ray Emission (SXRF) with photons of 11.8 keV energy and a focal spot of 5 × 2.5 μm 2 with especially high intensity of 2 × 10 9 photons/s have been performed on synthetic and natural volcanic glasses. A comparison of the possibilities and performances of these microanalytical methods is made. MDLs are given from the acquisitions obtained on synthetic glasses. Micro PIXE and micro SXRF were jointly applied to the study of trace elements in glass inclusions from the active volcanological system of Vulcano (Eolian Islands — Italy).