From urolithiasis to pathological calcifications: A journey at the interface between physics, chemistry, and medicine. A tribute to Michel Daudon

International audienceMichel Daudon is a worldwide recognized biologist who performed several major breakthroughs in the field of urolithiasis. It is indeed difficult to address his outstanding personality and his great contributions to urolithiasis. Michel Daudon studied many aspects of urolithiasis, from urine crystals to kidney stone morphoconstitutional analysis. He is the author of more than 500 scientific articles on urolithiasis, and more generally on pathological calcifications, including several books and nice articles in the New England Journal of Medicine, The Lancet, Kidney International, among many others. Michel Daudon is not only a prolific writer; his broad fields of interests range from chemistry to biology or renal pathology, but also clinical bedside subjects explain his success and his attractive way of explaining pathophysiological processes. He has already given more than 300 lectures, in France as abroad

Foreword to microcrystalline pathologies: combining clinical activity and fundamental research at the nanoscale

This contribution underlines the key role of physicochemical characterisation techniques in the area of medical research. The starting point centres on the Mid-InfraRed platform located at the Tenon hospital and dedicated to multidisciplinary functional investigations. In the last two decades, we have enhanced this platform by creating a network combining researchers from varied disciplines such as physicists, chemists, and clinicians. The resultant research dynamism is underscored by metrics such as 71 references in Pubmed and 129 in Web of Science, and the high impact of the journals in which we have published (New England Journal of Medicine, Kidney International, Chemical Review...). It is of paramount importance to disseminate these physicochemical techniques among young doctors, and to establish collaborations with appropriate private companies

Foreword to microcrystalline pathologies: combining clinical activity and fundamental research at the nanoscale

This contribution underlines the key role of physicochemical characterisation techniques in the area of medical research. The starting point centres on the Mid-InfraRed platform located at the Tenon hospital and dedicated to multidisciplinary functional investigations. In the last two decades, we have enhanced this platform by creating a network combining researchers from varied disciplines such as physicists, chemists, and clinicians. The resultant research dynamism is underscored by metrics such as 71 references in Pubmed and 129 in Web of Science, and the high impact of the journals in which we have published (New England Journal of Medicine, Kidney International, Chemical Review...). It is of paramount importance to disseminate these physicochemical techniques among young doctors, and to establish collaborations with appropriate private companies

Crystal size in μ\mu crystalline pathologies and its clinical implication

International audienc

Prevalence of metabolic abnormalities in patients with urolithiasis in Kinshasa, Democratic Republic of Congo

Introduction: metabolic abnormalities are key factors in urolithiasis patients because they can be modified to prevent the risk of urinary stones. The objectives of this study were to estimate the frequency of metabolic abnormalities in the urine of patients with urolithiasis and to determine their possible link with the chemical composition of stones. Methods: we conducted a cross-sectional study evaluating 73 patients referred for urolithiasis in 8 clinics in Kinshasa, between January 2017 and September 2019. Twenty four-hour or early morning urine were collected and analyzed in the Tenon Hospital in Paris. Parameters analyzed included pH, specific gravity, creatinine, uric acid, calcium, phosphate, oxalate, citrate and magnesium. Chi square test or chi-square likelihood-ratio and student's t test were used as statistical tests. Results: overall, 89% (n=65) of patients with lithiasis had metabolic abnormalities. Mean (SD) age of patients was 47.0 (14.2) years with male to female ratio of 1.6:1. The mean (SD) 24-hour diuresis was 1836.4 (1216.9)ml; the mean (SD) urine density was 1.018 (0.007); and the mean (SD) pH was 6.1(0.8). Hypocitraturia was the most frequently observed metabolic abnormality and was found in 76.7% patients. Other significant metabolic abnormalities were low magnesuria (35.6%), hyperoxaluria (11%), and low sulphaturia (74%). Whewellite (73.5%) was the main chemical component. The mean pH was higher in patients with carbapatite and struvite stones (p=0.031). Conclusion: this study suggests that inadequate diuresis and hypocitraturia were important lithogenic factors. The population should be encouraged to increase water intake to limit the frequency of urine super saturation with crystals

Features of gallstones in adult sickle cell patients

Morpho-constitutional analysis of gallstones revealed significant differences between sickle cell patients and other gallbladder stone formers. As expected, pigment stones, mainly composed of calcium bilirubinates, were the most common type of stones in the former (74.7 versus 22.5%, $p<10^{-6}$), which could be explained by haemolysis. However, if we consider that only 25% of sickle cell patients form stones in the bile ducts, this suggests that other factors could be involved such as mutations in the UGT1A1 gene. While calcium phosphates were found with the same frequency as the main component of gallstones in both groups, a high proportion of gallstones that had nucleated from carbapatite were observed in sickle cell patients in comparison to patients without sickle cell disease (23.5% versus 5.5%, $p<0.0001$). In addition, among sickle cell patients, those who were homozygous were more prone than heterozygous subjects to form pigment gallstones from calcium phosphate (31.4 versus 5.9%, $p<0.01$)

Features of gallstones in adult sickle cell patients

Morpho-constitutional analysis of gallstones revealed significant differences between sickle cell patients and other gallbladder stone formers. As expected, pigment stones, mainly composed of calcium bilirubinates, were the most common type of stones in the former (74.7 versus 22.5%, $p<10^{-6}$), which could be explained by haemolysis. However, if we consider that only 25% of sickle cell patients form stones in the bile ducts, this suggests that other factors could be involved such as mutations in the UGT1A1 gene. While calcium phosphates were found with the same frequency as the main component of gallstones in both groups, a high proportion of gallstones that had nucleated from carbapatite were observed in sickle cell patients in comparison to patients without sickle cell disease (23.5% versus 5.5%, $p<0.0001$). In addition, among sickle cell patients, those who were homozygous were more prone than heterozygous subjects to form pigment gallstones from calcium phosphate (31.4 versus 5.9%, $p<0.01$)

Scanning electron microscopy—a powerful imaging technique for the clinician

International audienc