Acidic polyanion poly(acrylic acid) prevents calcium oxalate crystal deposition.

Acidic macromolecules inhibit calcium oxalate nucleation, growth, aggregation and attachment to cells in vitro. To test for such an effect in vivo we used osmotic minipumps to continuously infuse several doses of the 5.1 kDa poly(acrylic acid) (pAA(5.

Regulation by macromolecules of calcium oxalate crystal aggregation in stone formers.

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.

Osteopontin is a critical inhibitor of calcium oxalate crystal formation and retention in renal tubules.

Calcium nephrolithiasis is the most common form of renal stone disease, with calcium oxalate (CaOx) being the predominant constituent of renal stones. Current in vitro evidence implicates osteopontin (OPN) as one of several macromolecular inhibitors of urinary crystallization with potentially important actions at several stages of CaOx crystal formation and retention. To determine the importance of OPN in vivo, hyperoxaluria was induced in mice targeted for the deletion of the OPN gene together with wild-type control mice.

Effects of urinary macromolecules on hydroxyapatite crystal formation.

Particle size analysis was combined with titration data obtained in constant-composition, hydroxyapatite (HA)-seeded, crystal growth assays. With addition of large amounts of HA (250 microg), titration rates were linear, new crystal formation was minimal, and aggregation effects could be detected. With addition of small amounts of HA (62.

Expression of osteopontin, a urinary inhibitor of stone mineral crystal growth, in rat kidney.

Cultured mouse kidney cortical cells secrete osteopontin, a bone matrix protein that is also found in urine. Osteopontin is associated with cell proliferation/tumerogenesis and also inhibits kidney stone mineral crystal growth [1]. Using antibodies raised against osteopontin isolated from the culture medium, we localized osteopontin in normal rat kidney.