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Based on the structure of kidney stones, it is likely that they form as aggregations of preformed crystals, mostly calcium oxalate monohydrate (COM). In this study, we examined the ability of a macromolecular mixture isolated from the urine of normal individuals and stone formers to inhibit aggregation of preformed COM seed crystals in a simple ionic solution using measurements of changes in the particle size distribution (PSD) of preformed COM crystal aggregates. We also examined the effect in this assay of a number of synthetic homopolymers, naturally occurring urine macromolecules, and binary mixtures thereof. The macromolecular mixtures from urine of normals and most stone formers reduced the degree of aggregation of the seed crystals, whereas 22% of stone former urine macromolecules either did not disaggregate or actually promoted further aggregation. Stone formers within one family shared this property, but a non-stone forming sibling did not. Polyanions, either synthetic or naturally occurring, induced disaggregation to an extent similar to that exhibited by normal urine macromolecules, while polycations had no effect on the PSD. However, mixing a polyanion, either poly-aspartate or osteopontin, with the polycation poly-arginine, changed their behavior from disaggregation to aggregation promotion. The disaggregating behavior of normal urinary macromolecules provides a defense against aggregation, but a minority of stone forming individuals lacks this defense, which may contribute to stone formation. [ABSTRACT FROM AUTHOR]

Net optical rotations of the hydrolyzates of precipitates from alkali-treated soy flour were measured and compared to those of non-alkali-treated controls. Soy flour was exposed to NaOH at pH 9.0 or 12.0 for 10, 30, 60, or 120 min at 60°C. Control samples were treated similarly with distilled water at an unadjusted pH of 6.7. Acid precipitates from the treatment mixtures were hydrolyzed, and the optical rotations of hydrolyzate solutions were measured. Higher pH and longer time of treatment resulted in decreased optical rotation; significant decreases occurred after 60 min or more at pH 9.0, and 10 min or more at pH 12.0. The results are consistent with L- to D-isomerization of amino acids. [ABSTRACT FROM AUTHOR]