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METHODS

Individual urine samples were normalised for natural variation in concentration using a total protein to creatinine ratio to calculate the volume contributing to the pooled sample. Differentially abundant proteins in pooled urine samples were identified using label-free nano-UPLC MS E analysis from two independent experiments using a total of 57 SF and 57 NSF. Enzyme-linked immunosorbent assay (ELISA) was used to validate the mass spectrometry findings and a calcium oxalate crystallization assay was performed to evaluate effects in vitro.

RESULTS

The urinary proteomic analysis identified 1063 proteins, of which 367 were unique to the stone former groups, 408 proteins were unique to the control pools and 288 proteins were identified for comparative quantification. Proteins found to be unique in stone-formers were involved in carbohydrate metabolism pathways and associated with disease states …