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The application of synchrotron radiation induced X-ray emission in the measurement of zinc and lead in Wistar rat ameloblasts |
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| Authors: | Arora Manish Kennedy Brendan J Ryan Chris G Boadle Ross A Walker D Murray Harland Cathy L Lai Barry Cai Zhonghou Vogt Stefan Zoellner Hans Chan Sheena W Y |
| Affiliation: | a Cellular and Molecular Pathology Research Unit, Department of Oral Pathology, Faculty of Dentistry, University of Sydney, Westmead Centre for Oral Health, Westmead Hospital, Westmead, NSW 2145, Australia b School of Chemistry, University of Sydney, NSW 2006, Australia c CSIRO Exploration and Mining, Geosciences, Building 28E, Monash University, Clayton, VIC. 3168, Australia d Electron Microscope Unit, ICPMR, Westmead Hospital, Westmead, NSW 2145, Australia e Australian Synchrotron Research Program, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia f Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA |
| Abstract: | 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). |
| Keywords: | Synchrotron radiation X-ray emission Ameloblasts Wistar rats Trace elements Zinc Lead |
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