Browsing by Author "Bazin, Dominique"

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    Recurrence rates of urinary calculi according to stone composition and morphology
    (Springer, 2018-10) Daudon, Michel; Jungers, Paul; Bazin, Dominique; Williams, James C., Jr.; Anatomy and Cell Biology, School of Medicine
    Few studies have examined the relative risk of recurrence of different stone types. The object of the present study was to evaluate the tendency for stone recurrence as a function of major mineral composition of the stones and morphological characteristics of the stones. This study was carried out using 38,274 stones for which we had data available to specify if the stone was from the first or a subsequent urinary stone episode. Stones were analyzed for morphology by stereomicroscope and for composition by infrared spectroscopy. Overall, 42.7% of stones were from patients who had had a previous stone event, with these being more frequent in men (44.4%) than in women (38.9%, p < 0.0001). Age of first stone occurrence was lowest for dihydroxyadenine (15.7 ± 16.6 years) and highest for anhydrous uric acid (62.5 ± 14.9 years), with the average age of first stones of calcium oxalate falling in the middle (40.7 ± 14.6 years for calcium oxalate dihydrate, and 48.4 ± 15.1 years for calcium oxalate monohydrate, COM). By composition alone, COM was among the least recurrent of stones, with only 38.0% of COM stones coming from patients who had had a previous episode; however, when the different morphological types of COM were considered, type Ic—which displays a light color, budding surface and unorganized section—had a significantly greater rate of recurrence, at 82.4% (p < 0.0001), than did other morphologies of COM. Similarly, for stones composed of apatite, morphological type IVa2—a unique form with cracks visible beneath a glossy surface—had a higher rate of recurrence than other apatite morphologies (78.8 vs. 39–42%, p < 0.0001). Stone mineral type alone is insufficient for identifying the potential of recurrence of the stones. Instead, the addition of stone morphology may allow the diagnosis of highly recurrent stones, even among common mineral types (e.g., COM) that in general are less recurrent.
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    Using micro computed tomographic imaging for analyzing kidney stones
    (French Académie des Sciences, 2021) Williams, James C., Jr.; Lingeman, James E.; Daudon, Michel; Bazin, Dominique; Anatomy, Cell Biology and Physiology, School of Medicine
    Stone analysis is a critical part of the clinical characterization of urolithiasis. This article reviews the strengths and limitations of micro CT in the analysis of stones. Using micro CT alone in a series of 757 stone specimens, micro CT identified the 458 majority calcium oxalate specimens with a sensitivity of 99.6% and specificity of 95.3%. Micro CT alone was also successful in identifying majority apatite, brushite, uric acid, and struvite stones. For some minor minerals—such as apatite in calcium oxalate or calcium salts in uric acid stones—micro CT enables the detection of minute quantities well below 1%. The addition of a standard for calibrating X-ray attenuation values improves the ability of micro CT to identify common stone minerals. The three-dimensional nature of micro CT also allows for the visualization of surface features in stones, which is valuable for the study of stone formation.
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    Using mid infrared to perform investigations beyond the diffraction limits of microcristalline pathologies: advantages and limitation of Optical PhotoThermal IR spectroscopy
    (Academie des Sciences, 2022) Bazin, Dominique; Bouderlique, Elise; Tang, Ellie; Daudon, Michel; Haymann, Jean-Philippe; Frochot, Vincent; Letavernier, Emmanuel; Van de Perre, Els; Williams, James C.; Lingeman, James E.; Borondics, Ferenc; Urology, School of Medicine
    Understanding the physico-chemistry related to cristalline pathologies constitutes a challenge in several medical specialities such as nephrology, dermatology or oncology. Regarding nephrology, the chemical diversity of concretions such as kidney stones calls for characterization techniques to determine the chemical composition of concretions. The starting point of this contribution is given by Fourier Transform InfraRed (FTIR) spectroscopy which is routinely used at the hospital to determine the chemical composition of kidney stones as well as ectopic calcifications present in kidney biopsy. For kidney stones, the quantity of sample is sufficient to perform a significant analysis through classical FTIR. For ectopic calcifications, FTIR can be inefficient in the case of calcification in the tissue when their size is less than 10 m. For such samples, Optical PhotoThermal IR (OPT-IR) spectroscopy may constitute a way to overcome this experimental difficulty through the acquisition of IR spectrum with a spatial resolution close to 500 nm. To illustrate such opportunity, we first compare the IR spectrum acquired with a classical experimental set-up related to classical IR spectroscopy to IR spectrum collected with a OPT-IR one for different compounds namely calcium oxalate monohydrate, calcium oxalate dehydrate, calcium phosphate apatite and magnesium ammonium phosphate hexahydrate. Such comparison helps us to assess specificity of OPT-IR. Then, we consider several pathological calcifications associated to hyperoxaluria, adenine phosphoribosyltransferase (APRT) deficiency or the presence of Randall’s plaque. We will see that the nanometer spatial resolution constitutes a major advantage versus a micrometre one. Also, in the case of Randall’s plaque, we show that OPT-IR can determine the chemical composition of microscopic concretion without any kind of preparation. Such experimental fact is clearly a major advantage. Finally, we also extended this first investigation in nephrology by considering breast calcifications. In that case, if the number of chemical phases is quite low compared to the number of chemical phases identified in ectopic calcifications present in kidney (four instead of 24), the challenge is related to the possibility to distinguish between the different calcium phosphate namely amorphous carbonated calcium phosphate, CA and whitlockite. The complete set of data indicates the limitations and the advantages of OPT-IR spectroscopy.