Crystallization of Ammonium Urate in Bottlenose Dolphin Renal Stones
Abstract
The overarching objective of this proposal is to identify effective molecular inhibitors of ammonium urate (NH4U) crystallization and to establish fundamental understandings of NH4U crystal growth in dolphin urine, and combine these two efforts in studies with the intent of characterizing inhibitor performance in natural environments of stone formation. The proposed effort has been subdivided into the following three tasks that collectively focus on the improvement of Navy dolphin health and the establishment of preventative therapeutics to curtail ammonium urate stone formation in both dolphins and humans:Task 1, Identifying Inhibitors of NH4U Crystallization: commercially available molecules with similar functionality as urate will be screened in bulk crystallization assays to identify lead candidates. The most promising inhibitors will be examined in more detail using ex situ electron microscopy and in situ atomic force microscopy (AFM) to probe the molecular mechanisms of inhibitor-crystal interactions.Task 2, Crystallization Assays in Biological Media: The established platform for in vitro NH4U crystallization in biomimetic media will be extended to studies in archived dolphin urine samples provided by PIs at the National Marine Mammal Foundation (NMMF). The results of these assays will be analyzed by Rimer (UH). The anticipated outcome of these experiments is the establishment of conditions leading to promoted growth of NH4U crystals. Solubility and the kinetic rates of NH4U crystal growth will be assessed, thereby providing a foundation for detailed studies in Task 3. Samples provided by NMMF will test a range of archived dolphin urine samples from studies of varying diets and regions of the US.Task 3, Effects of Crystal Inhibitors in Native Environments: The results of Tasks 1 and 2 will be leveraged in an effort to understand the effects of inhibitors in native environments of dolphin kidney stones. In a previous study, Rimer (UH) observed a synergistic cooperativity between the drug hydroxycitrate and organic species (e.g. proteins and biomolecules) present in urine (human) that have led to unexpected enhancement of crystal growth inhibition. The exact nature of these cooperative interactions are not well understood given the complexity of urine; however, we observed similar effects for combinations of urinary proteins. We anticipate that similar findings will be observed for select molecules identified in Task 1. The outcome of this study is the establishment of structure-performance relationships to help guide the design of preventative drugs for dolphin kidney stones. APPROVED FOR PUBLIC RELEASE.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 11, 2020
- Source ID
- N000142012083
Entities
People
- Jeffrey D Rimer
Organizations
- Office of Naval Research
- United States Navy
- University of Houston System