The effect of preincubation of seed crystals of uric acid and monosodium urate with undiluted human urine to induce precipitation of calcium oxalate in vitro : implications for urinary stone formation

• Published in: Molecular medicine (Cambridge, Mass.) Mass.), 2002-09, Vol.8 (9), p.525-535
• Main Authors: Grover, Phulwinder K, Ryall, Rosemary L
• Format: Article
• Language: English
• Subjects: Calcium Oxalate - metabolism; Carbon Radioisotopes - metabolism; Crystallization; Particle Size; Uric Acid - metabolism; Urinary Calculi - etiology; Urinary Calculi - metabolism; Urine - physiology
• ISSN: 1076-1551; 1528-3658
• DOI: 10.1007/BF03402162

Previous studies demonstrated that crystals of uric acid (UA) and sodium urate (NaU) can induce the precipitation of calcium oxalate (CaOx) from its inorganic metastable solutions, but similar effects have not been unequivocally shown to occur in urine. The aim of this investigation was to determine whether preincubation of these seeds with urine alter their ability to induce deposition of CaOx from solution and thus provide a possible explanation for discrepancy of results obtained from aqueous inorganic solutions and undiluted urine. The effects of commercial seed crystals of UA, NaU and CaOx (6 mg/100 ml) on CaOx crystallization were compared in a solution with the same crystals that had been preincubated for 3 hours with healthy male urine. A Coulter Counter was used to follow the crystallization and decrease in soluble (14) C-oxalate was measured to determine the deposition of CaOx. The precipitated particles were examined by scanning electron microscopy (SEM). The preincubated seeds were demineralized and proteins released were analyzed by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE). Analysis of (14) C-oxalate data revealed that while treated UA seeds did not affect CaOx deposition, those of NaU and CaOx inhibited the process by 51.9 (p