Basic Science: Stones

Moderated Poster Session

MP2-3 - Exploring Thermodynamics of Kidney Stone Compounds to Optimize Calcium Oxalate Kidney Stone Dissolution and Crystallization

Thursday, September 20
4:00 PM - 6:00 PM
Location: Room 242B

Introduction & Objective : Prevalence of kidney stones is increasing throughout the world. Laser lithotripsy via ureteroscopy is performed to break up the stones into 0.5 mm, which may remain behind. This “dust” may become a nidus for crystal deposition and lead to recurrence of kidney stones. Our aim is to explore thermodynamic theories to aid in determination of ideal conditions for crystallization and dissolution of calcium oxalate kidney stone fragments.  


Methods : Based on the study by Thongboonkerd et. l, dissolution agent and chelator will be the solution of interest. We use the Gibbs equation (ΔG = ΔH - TΔS) to calculate and predict ideal conditions for stone dissolution.  Calcium oxalate crystals were formed by combining salts containing both calcium and oxalate in accordance with the chemical equation: Ca2+ + C2O42- → CaC2O4.  Dissolution agent sodium citrate and EDTA chelator are optimal compounds for calcium oxalate dissolution. For creation of a stone crystal model, OPN at physiologic pH, protein matrix (lab made Human Placental Matrix-HPM), and calcium oxalate were combined in artificial urine.   


Results : The measured dissolution enthalpies of the various calcium oxalate hydrates were determined via calorimetric experiments observed.  In water, calcium oxalate monohydrate requires 21.1 kJ/mol for dissolution, and the formation of sodium oxalate produces approximately 16.6 kJ, both at 25 C.  Calcium-EDTA produces 50 kJ of energy in TRIS buffer at pH 7.5 which provides the required energy for breaking calcium oxalate and hydrogen bonds.  The isoelectric point of OPN is 4.7, thus at pH close to 6.5, free calcium ions will primarily bind OPN which will result in less COM crystallization observed under microscopy. Crystals were observed under fluorescent and light microscopy.  HPM grown crystals promoted crystal growth over its matrix.  With no OPN present, there is more crystal growth compared to the crystals grown in the presence of OPN which may indicate crystallization suppression activity by OPN.  


Conclusions : Theoretically, ideal dissolution agent was found to be sodium citrate with EDTA on TRIS at physiologic pH, due to its favorable thermodynamic interactions. Osteopontin, will either enhance or inhibit stone formation depending on the pH related to its isoelectric point. Crystallization occurred more readily at low pH for the agents used.

Noa Grooms

Biomedical Engineering Candidate 2018
University of Florida

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    Nicole Bird

    Biomedical Engineering Candidate 2018
    U. of Florida

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      Nicole Bird

      Biomedical Engineering Candidate 2018
      U. of Florida

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        Steven Arce

        Faculty, Biomedical Engineering
        U. of Florida, College of Engineering

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          Steven Arce

          Faculty, Biomedical Engineering
          U. of Florida, College of Engineering

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            Victoria Bird

            Assistant Professor of Urology, Affiliate Professor of Biomedical Engineering, Director
            U. of Florida, College of Medicine and College of Engineering, National Medical Association and Research Group LLC

            National Medical Association and Research Group, Director.

            Latina Women's League, Director of Health Projects.

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              Victoria Bird

              Assistant Professor of Urology, Affiliate Professor of Biomedical Engineering, Director
              U. of Florida, College of Medicine and College of Engineering, National Medical Association and Research Group LLC

              National Medical Association and Research Group, Director.

              Latina Women's League, Director of Health Projects.

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                Nicole Anne Bohmann

                n/a
                University of Florida

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                  Nicole Anne Bohmann

                  n/a
                  University of Florida

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                    Michele Dill

                    Biomedical Engineering candidate 2019
                    Biomedical Engineering, College of Engineering

                    Michele Dill is an undergraduate Biomedical Engineering student and a prospective PhD student at the University of Florida in Gainesville, FL. Past conferences attended include the Biomedical Engineering Society Annual Meeting and the Florida Undergraduate Research Conference. Michele has conducted research relating to oral phosphate binders for patients with renal failure, an externally triggered drug delivery system for the treatment of Hepatocellular Carcinoma, and an esophageal cooling device for use in cardiac ablation procedures. Michele will be presenting both preliminary studies and theoretical research focusing on the dissolution of residual kidney stone fragments following ureteroscopy at the WCE meeting. The focus of her WCE research is the dissolution of calcium oxalate. In 2019, Michele plans to enter a PhD program within Biomedical Engineering with a focus on tissue engineering for the development of improved in vivo models of organ systems with the intention of improving our understanding of healthy and diseased states.

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