Concentration of a potent calcium oxalate monohydrate crystal growth inhibitor in the urine of normal persons and kidney stone patients by ELISA‐based assay system employing monoclonal antibodies

Abstract

Standardized calcium oxalate monohydrate (COM) crystal growth assay system was employed to study the ability of various test samples to influence growth rates of COM crystals. The inhibitory activity (IA) of various samples was expressed in terms of inhibitory units. Urine samples obtained from normal persons and kidney stone patients were found to have IA of 3.18 +/- 0.62 and 1.02 +/- 0.08, respectively. A potent inhibitor having molecular weight between 14.2 and 16.2 kDa was found to be primarily responsible for the differences observed in the urinary IAs between normal persons and kidney stone patients. The potent inhibitor was found to be tightly associated with a chromophore resembling Urobilirubin. An ELISA based assay system, using monoclonal antibodies against the above most potent inhibitor confirmed the difference observed in the urinary IA between the normal persons and kidney stone patients. This assay system has the potential to be routinely used to screen human beings for potential stone formers.

Oxidative Modifications Switch Modulatory Activities of Urinary Proteins From Inhibiting to Promoting Calcium Oxalate Crystallization, Growth, and Aggregation

“…By contrast, the nonmodified urinary proteins inhibited such stone formation mechanisms, consistent with the previous findings demonstrating that the urine from healthy individuals protects the stone nidus formation and retention of CaOx crystals in renal tubular lumens and parenchyma ( 12 , 35 , 59 ). This is the first evidence showing that oxidative stress condition is directly involved in the primary phase of kidney stone formation and is not just the secondary effect from induction of renal tubular cell injury or inflammatory response.…”

Nephrolithiasis: Molecular Mechanism of Renal Stone Formation and the Critical Role Played by Modulators

“…We also purified, identified, and characterized novel proteins from human renal stone matrix. Some of them were potent inhibitors like urobilirubin (14.2–16.2 kDa) [227], a 36 kDa inhibitor protein [228], anionic protein like human phosphate cytidylyltransferase-1, β (42 kDa), [145, 146] cationic proteins like histone-lysine N-methyltransferase (53 kDa), inward rectifier K channel (44 kDa), and protein Wnt-2 (42 kDa) [148]. 2D map of  >3 kDa fraction from matrix of CaOx stone revealed the presence of disheveled-associated activator morphogenesis (123.9 kDa), glutamate receptor delta-1 subunit (113 kDa), caspase recruitment domain-containing protein (114.8 kDa), ALBU_BOVIN (71.2 kDa), VP7 glycoprotein precursor (37.5 kDa), chymotrypsinogen A (26.2 kDa), and plasminogen (15.7 kDa).…”

Effect of Age, Sex and Pregnancy on Levels of Urinary Inhibitors of mineralization in Human Beings

“…Based upon the studies that qualitative and quantitative differences exist in the urinary inhibitors between male and female sexes of normal human beings and between normal subjects and kidney stone patients of identical sex, a role has been assigned to the urinary inhibitors in the etiology of renal calculosis [14][15][16][17] . Studies have further shown that the above differences in urinary inhibitors between normal adult male and female subjects or normal and kidney stone patients of identical sex are primarily due to the differences in the polypeptides having molecular weights between 2-12 thousand Daltons 18 . Interestingly, in contrast to adult human beings, where males have been found to be at least three times more prone to renal calculosis as compared to adult females, equal tendency of renal calculosis has been reported in males and females during their childhood [19][20] .…”