Crystal Aggregation in Kidney Stone

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DESCRIPTION (provided by applicant): Kidney stones form as aggregates of various mineral phases, but calcium oxalate monohydrate (COM) is the most prevalent. Prior research efforts have failed to identify either a urine test that identifies stone formers or effective therapies preventing stone formation. We hypothesize that macromolecules in the urine of normal healthy adults prevent the pathologic aggregation events that lead to kidney stone formation, and that stone formers manifest some alteration in this protective mechanism. In this revised application, we propose to use a combination of bulk crystallization and microscopic characterization methods to identify specific chemical structural features of macromolecules that lead to a defect in aggregation inhibition, through a research protocol with two Specific Aims. The two Specific Aims are: (1) to use previously established bulk crystallization methods to study single macromolecules (from either biological or chemical origins) and combinations of polyanions and polycations to identify the chemical structural features critical to the COM aggregation processes and (2) to use atomic force microscopy to directly measure the influence of macromolecules studied under Aim 1 on the force of adhesion at specific COM crystal faces. In the later phases of these studies, we will use atomic force microscopy to measure directly the adhesion force between oriented crystal surfaces in the presence of various macromolecules in solution. The use of AFM will provide important information about the adsorption of macromolecules containing specific chemical functional groups with selected COM surfaces, that is not obtainable in any other way. Our preliminary data have shown important correlations between face selective binding and crystal phase and morphology. Extending the linkage of specific chemical functional groups to the aggregation process will allow for the intelligent design of drugs that could prevent stone formation by blocking aggregation processes.