Bladder secretion of inhibitors of calcium oxalate crystal growth

Protein profiling of organic stone matrix and urine from dogs with urolithiasis

Two-thirds of the organic matrix in urinary stones consists of proteins. Their relationship to calculogenesis remains controversial with regard to their effect as inhibitors or promoters during stone formation. The purpose of the present study was to determine the differences in peptide and protein pattern between the urine of stone formers (n = 23) and control dogs (n = 12), as well as between organic matrix of different urinary stones (struvite n = 11, calcium oxalate n = 8, uric acid n = 4) using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Specific differences in protein and peptide profiles were found in the organic matrix of different mineral compositions. Characteristic differences were also found in urinary peptide and protein pattern especially in molecular masses below 20 kDa between affected and healthy dogs. Based on the obtained molecular masses they were in some cases tentatively identified as proteins that are known to be involved in stone formation in humans. The study shows that in dogs, specific-urinary peptides and proteins might be associated with urolithiasis. It indicates the importance to further characterize those proteins for possible diagnostic purposes in prognosis and therapy.

High resolution 2-dimensional electrophoretic analysis of proteins in saline bladder washings

Human urine contains a spectrum of proteins derived from various organs in the body. This investigation was undertaken to identify a group of proteins secreted primarily by bladder urothelium. Saline bladder washouts were collected from 9 male and 4 female patients undergoing routine cystoscopic examination. Each sample was sieved, desalted, freeze-dried and solubilized in urea mix. identical amounts of proteins were pooled according to donor sex. All individual and pooled samples were then subjected to 2-dimensional gel analysis using the ISO-DALT system. Profiles of both groups of subjects were highly reproducible, comparable and resembled those of urine and plasma. Several hundred spots were visualized although most of them as yet remain unrecognized. The proteins identified in bladder washouts include albumin, transferrin, IgG gamma-heavy chain, Gc-globulin, alpha 1-antichymotrypsin, alpha 1-antitrypsin, alpha 1-acid glycoprotein, G4, IgG light chains, alpha 1-microglobulin, and low and high density lipoproteins. Most importantly, while some abundant urinary macromolecules such as Tamm-Horsfall mucoprotein and most acidic urinary proteins were undetectable, albumin and transferrin were relatively less expressed. The 2-dimensional profiles we developed can be used as a data base to study urothelium derived proteins in various disease conditions such as bladder cancer.

An unidentified macromolecular inhibitory constituent of calcium oxalate crystal growth in human urine

We have detected and isolated a macromolecular constituent in normal human urine possessing calcium crystal growth inhibitory activity. The purification procedure consisted of two anion exchange chromatographies and one affinity chromatography. The crystal growth inhibitor was found to be heterogeneous in net charge as well as in size. It has not been identified. It is not an uronic acid-containing glycosaminoglycan, hitherto presumed to be responsible for the inhibitory activity. Whether an urinary fragment of inter-alpha-trypsin inhibitor is responsible has yet to be resolved.

The influence of urinary macromolecules on calcium oxalate monohydrate crystal growth

The Constant Composition (CC) kinetics method has been used for studying the mineralization of calcium oxalate monohydrate (COM) at sustained supersaturations in the presence of pre-bladder urine and macromolecules isolated from normal urine and kidney and bladder stones. The method is especially sensitive for investigating the inhibitory activities of these urinary macromolecular components (UMMC) and matrix macromolecular components (MMMC) with a coefficient of variation in growth rate of approximately 2%. Significant COM mineral inhibition was observed in a wide molecular weight region of urine components. Urine removed directly from the kidney showed appreciable inhibitory activity towards COM crystallization. Normal urinary proteins and the dissolved precipitate resulting from urine centrifugation were fractionated by gel filtration. The resulting solutions were mostly COM mineralization inhibitors. Electrodialysis was utilized to isolate the MMMC (greater than 7000 d) of renal and bladder calculi. While these solutions inhibited COM crystallization, they were also found to be calcium binders as measured by the calcium electrode.

The effect of some urinary stone inhibitors on membrane interaction potentials of stone crystals

The effect of stone growth inhibitors (citrate, pyrophosphate, ethane diphosphonate, methane diphosphonate, chondroitin sulfate A, chondroitin sulfate C, heparin and ribonucleic acid) on crystal-membrane interactions of whewellite, weddellite, apatite, brushite, struvite, uric acid, monosodium urate and quartz (control) stones was quantitated. As a model for the initial retention of microcrystals by kidney epithelial membranes, crystal-induced membranolysis of red blood cells served as a measure of crystal-membrane interactions. The inhibitors induced changes in hemolytic potential from approximately 320 per cent enhancement to 80 per cent inhibition. No inhibitor behaved the same way for all crystals studied. However, some crystals showed consistent trends in altered hemolytic potential in the presence of inhibitors. These crystals included weddellite and sodium urate, which were inhibited consistently, and apatite and quartz, which were enhanced consistently. Whewellite, uric acid, brushite and struvite exhibited mixed patterns in the altered hemolytic potentials owing to the inhibitors.