Micro-Composition of Human Urinary Calculi Using Advanced Imaging Techniques.
Common methods of commercial urolithiasis analysis, such as light microscopy and Fourier transform infrared spectroscopy, provide limited or no information on the molecular composition of stones, which is vital when studying early stone pathogenesis. We used synchrotron radiation based microfocused x-ray fluorescence, x-ray absorption and x-ray diffraction advanced imaging techniques to identify and map the elemental composition, including trace elements, of urinary calculi on a μm (0.0001 cm) scale.
Materials and methods:
Human stone samples were obtained during serial percutaneous nephrolithotomy and ureteroscopy procedures. A portion of each sample was sent for commercial stone analysis and a portion was retained for synchrotron radiation based advanced imaging analysis.
Synchrotron radiation based methods of stone analysis correctly identified stone composition and provided additional molecular detail on elemental components and spatial distribution in uroliths. Resolution was on the order of a few μm.
Knowledge of all elements present in lithogenesis at this detail allows for better understanding of early stone formation events, which may provide additional insight to prevent and treat stone formation.
Article: Pathogenesis of NephrolithiasisThe Journal of urology 11/2012; 189(2). DOI:10.1016/j.juro.2012.11.069 · 4.47 Impact Factor
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ABSTRACT: The pathophysiology of the various forms of urinary stone disease remains a complex topic. Epidemiologic research and the study of urine and serum chemistries have created an abundance of data to help drive the formulation of pathophysiologic theories. This article addresses the associations of urinary stone disease with hypertension, cardiovascular disease, atherosclerosis, obesity, dyslipidemia, diabetes, and other disease states. Findings regarding the impact of dietary calcium and the formation of Randall's plaques are also explored and their implications discussed. Finally, further avenues of research are explored, including genetic analyses and the use of animal models of urinary stone disease.Urologic Clinics of North America 02/2013; 40(1):1-12. DOI:10.1016/j.ucl.2012.09.006 · 1.20 Impact Factor
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ABSTRACT: Purpose: We evaluate a compact portable system for immediate automated postoperative ex vivo analysis of urinary stone composition using Raman spectroscopy. Analysis of urinary stone composition provides essential information for the treatment and metaphylaxis of urolithiasis. Currently infrared spectroscopy and x-ray diffraction are used for urinary stone analysis. However, these methods may require complex sample preparation and costly laboratory equipment. In contrast, Raman spectrometers could be a simple and quick strategy for immediate stone analysis. Materials and methods: Pure samples of 9 stone components and 159 human urinary calculi were analyzed by Raman spectroscopy using a microscope coupled system at 2 excitation wavelengths. Signal-to-noise ratio, peak positions and the distinctness of the acquired Raman spectra were analyzed and compared. Background fluorescence was removed mathematically. Corrected Raman spectra were used as a reference library for automated classification of native human urinary stones (50). The results were then compared to standard infrared spectroscopy. Results: Signal-to-noise ratio was superior at an excitation wavelength of 532 nm. An automated, computer based classifier was capable of matching spectra from patient samples with those of pure stone components. Consecutive analysis of 50 human stones demonstrated 100% sensitivity and specificity compared to infrared spectroscopy (for components with more than 25% of total composition). Conclusions: Our pilot study indicates that Raman spectroscopy is a valid and reliable technique for determining urinary stone composition. Thus, we propose that the development of a compact and portable system based on Raman spectroscopy for immediate, postoperative stone analysis could represent an invaluable tool for the metaphylaxis of urolithiasis.The Journal of urology 06/2013; 190(5). DOI:10.1016/j.juro.2013.06.024 · 4.47 Impact Factor