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Query: UMLS:C0451641 (urolithiasis)
 3,973 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Physico-chemical investigation of urolithiasis today is mostly focused on applying physico-chemical description of precipitation processes to the stone formation with the aim to distinguish between stone formers and nonstone formers. This is done by calculating supersaturation for different solid phases which can be formed in urine using data obtained by urine analysis and existing solubility product, dissociation and complexation constants. In order for this approach to succeed it is of utmost importance that system is described as detailed as possible, i.e., that all species that can be formed are taken into account. Magnesium hydrogenurate octahydrate, Mg(C5H3N4O3)28H2O (Mg(HU)2.8H2O), is among species which can precipitate in the urine and for which solubility data doesn't exist. In order to fill this void crystals of Mg(C5H3N4O)2.8H2O phase I and phase II have been prepared and characterized. Solubility product constant of Mg(C5H3N4O3)2.8H2O phase I in water at 37 degrees C and phase II at different temperatures, pH and in different solvents have been determined by measuring total concentration of uric acid and magnesium ions in solutions at different time periods. Results show that in water at 37 degrees C thermodynamically less stable phase I is more soluble (Ksp = (5.64 +/- 0.20).10(-9) mol3 dm(-9)) than phase II (Ksp = (1.66 +/- 0.13).10(-9) mol3 dm(-9)). Solubility of Mg(HU)2.8H2O phase II increases with temperature. At equilibrium the solubility of phase II is the lowest in the presence of excess of magnesium ions, while solubility in the presence of uric acid is comparable with the one obtained in water.
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PMID:Influence of pH, temperature and common ion on magnesium hydrogenurate octahydrate solubility. 2040 30

By means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nano-particle size analyzer, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the composition, morphology, particle size and zeta potential of urinary microcrystalline in urine of magnesium ammonium phosphate stone formers were investigated. The components of stones were also analyzed. The results showed that there was a close relationship among stone components, urinary microcrystalline composition and urine pH. A high pH value of 6.5 or more usually appeared in the urine of magnesium ammonium phosphate stone formers. The main component of urine microcrystalline was magnesium ammonium phosphate crystals with different crystal water such as monohydrate or hexahydrate. Magnesium ammonium phosphate crystals are mainly petal-shaped, crosswise shape. These microcrystalline have an uneven particle size distribution, a wider distribution range, and apparent aggregation. There is no significant difference in the zeta potential between the magnesium ammonium phosphate stone formers (mean (-9.83 +/- 0.66) mV) and healthy control subjects (mean (-10.74 +/- 0.25) mV). This study can help predict the occurrence of urolithiasis, and provide inspiration to the prediction of the type of urinary stones.
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PMID:[Composition analyses of urinary microcrystalline in urine of magnesium ammonium phosphate stones formers and its relationship with the stones formation]. 2142 81

Experimental urolithiasis was induced in 80 white non-inbred male rats by adding 0.75% ethylene glycol and 2% ammonium chloride to drinking water by Fan et al. After significant differences in crystalluria, oxaluria and urine pH were achieved in hyperoxaluric rats vs controls one, hyperoxaluric rats were given magnesium (Mg) salts Mg chloride, Mg L-aspartate either alone or in combination with pyridoxine hydrochloride (B6) in comparison with Mg sulfate and magne B6 (mg lactate in combination with B6) in a dose of 50 mg of elementary Mg per 1 kg of body weight. All the rats were fed with Mg-adequate diet containing 0.84 g of Mg oxide (0.5 g of elementary Mg per kg of diet). Calcium-oxalate urolithiasis has developed in rats taking ethylene glycol and ammonium chloride for 28 days. An urinary oxalates levels increased threefold, oxalate/creatinine--fourfold. Calcium oxalate crystals were detected in the urine of rats drinking solution of ethylene glycol and ammonium chloride, pH decreased by 20%, fractional excretion (FE) of Mg increased by 60%, FE of phosphate--by 58.2%, FE of calcium--by 95.8%, creatinine clearance lowered by 39.2% in comparison with intact group. Magnesium salts administration resulted in reduction of urine oxalates, crystalluria, phosphate excretion, Ca/Mg and oxalate/creatinine ratios, increased urine pH and creatinine clearance. Mg L-aspartate in combination with vitamin B6 appeared the most effective salt and significantly more effective than magnesium sulfate.
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PMID:[Effects of magnesium salts on the course of experimental calcium-oxalate urolithiasis]. 2181 54

The present study investigated the prevalence of uroliths in fattening pigs and assessed the composition of these urinary tract concrements. In total, 2,432 urinary bladders were sampled in the slaughterhouse and checked for abnormal content. Urinary samples were analysed microscopically, and samples of the urinary bladder wall were tested for histological signs of inflammation. The composition of the concrements was examined by infrared spectrophotometry. Macroscopic and microscopic abnormalities were detected in 8.4% and 52.8% of the samples respectively. Magnesium ammonium phosphate (struvite), calcium oxalate dihydrate (COD), calcium carbonate (calcite), calcium oxalate monohydrate (COM) and amorphous crystals were detected. Analysis of stones showed COD in all samples in different proportions. The calcium content of examined stones was always considerable (up to 34%), in contrast to the magnesium content which represented max 1.9%. Struvite was found in one third of the samples, but was never part of stones and grit. COD crystals were the second most common microscopic crystal. These COD crystals and some COD stones had a rectangular shape, and therefore, they can be harmful to the bladder mucosa. In conclusion, uroliths are present in a large proportion of male fattening pigs, and consequently, urinary concrements pose a life-threatening risk for urethra obstruction in male pigs. Further research is warranted to identify potential risk factors for urolithiasis and microscopic crystals.
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PMID:Prevalence and chemical composition of uroliths in fattening pigs in Belgium. 3144 Nov 26


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