CALCIUM-OXALATE CRYSTAL MATRIX EXTRACT - THE MOST POTENT MACROMOLECULAR INHIBITOR OF CRYSTAL-GROWTH AND AGGREGATION YET TESTED IN UNDILUTEDHUMAN URINE IN-VITRO

Demineralization of calcium oxalate (CaOx) crystals precipitated from human urine in vitro yields an organic crystal matrix extract (CME) co nsisting predominantly of a single protein which we originally named c rystal matrix protein but have subsequently shown to be a urinary form of prothrombin activation peptide fragment 1 (F1). The aim of this st udy was to determine whether CME is a promoter or inhibitor of CaOx cr ystallization. The effect of CME on CaOx crystal growth and aggregatio n was tested using a standard seeded crystallization system, and its e ffect quantified by use of particle size analysis and a computer model . In addition, the effect of CME on the crystallization of CaOx was te sted in undiluted, ultrafiltered human urine using Coulter Counter ana lysis and scanning electron microscopy. It was shown that CME is a pot ent inhibitor of CaOx crystal growth and aggregation in a seeded metas table solution. However, of greater significance is that at a concentr ation of 10 mg/l it completely reversed the formation of large crystal line aggregates that form upon the removal of urinary macromolecules f rom undiluted urine. It was concluded that CME is the most po tent mac romolecular urinary inhibitor yet to be tested in urine in vitro. By p reventing the aggregation of newly formed crystals, the components of CME may significantly reduce the probability of particle retention in vivo and therefore the occurrence of urolithiasis.