Human Kidney Stones Research Articles

Development of a model for assessment of biomaterial encrustation in the upper urinary tract

A need exists for ureteral stent materials capable of preventing or reducing encrustation. The aim of this study, therefore, was to develop an in vitro model producing biomaterial encrustation similar to that on stents in vivo. Three models were designed and evaluated. Polyurethane stent sections were immersed in human urine (37 °C, 5% CO 2): (1) with and (2) without crushed human kidney stone and (3) in an artificial urine (37 °C, 5% CO 2). Encrustation of similar composition, as determined by infrared spectroscopy, X-ray diffraction and energy dispersive X-ray analysis, formed on stent materials in vivo, in artificial urine and in human urine with crushed kidney stone. Magnesium ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite) predominated in all encrustations. The reproducibility and ease of use of the artificial urine model provided optimum encrustation assessment of materials presently used in ureteral stents and evaluation of novel biomaterials.

Ultrastructural immunodetection of osteopontin and osteocalcin as major matrix components of renal calculi.

The organic matrix of renal calculi has long been considered to influence the crystal growth that occurs in these pathological mineral deposits. Recent advances in characterizing individual organic moieties from mineralized tissues in general and the combined use of antibodies raised against these molecules with different immunocytochemical approaches have allowed their precise distribution to be visualized in a variety of normal and pathological mineralized tissues. The present ultrastructural study reports on the epithelial expression and extracellular localization of several noncollagenous proteins in rat and human kidney stones using high-resolution colloidal-gold immunocytochemistry. To this end, we have examined in an ethylene glycol-induced calcium oxalate model of urolithiasis in the rat, and in human kidney stones, the distribution of certain noncollagenous and plasma proteins known to accumulate in bone and other mineralized tissues that include osteopontin, osteocalcin, bone sialoprotein, albumin, and alpha 2HS-glycoprotein. Of these proteins, osteopontin (uropontin) and osteocalcin (or osteocalcin-related gene/protein) were prominent constituents of the calcium oxalate-associated crystal "ghosts" found in the nuclei, lamellae, and striations of the organic matrix of lumenal renal calculi in the rat and of small crystal ghosts found within epithelial cells. Immunocytochemical labeling for both proteins of the content of secretory granules in tubular epithelial cells from treated rats, together with labeling of a similarly textured organic material in the tubular lumen, provides evidence for cosecretion of osteopontin and osteocalcin by epithelial cells, their transit through the urinary filtrate, and ultimately their incorporation into growing renal calculi. In normal rat kidney, osteopontin was localized to the Golgi apparatus of thin loop of Henle cells. In human calcium oxalate monohydrate stones, osteopontin was similarly detected in the lamellae and striations of the organic matrix. Based on these data, it is proposed that during urolithiasis, secretion of osteopontin (uropontin) and osteocalcin (or osteocalcin-related gene/protein), and the subsequent incorporation of these proteins into kidney stone matrix, may influence the nucleation, growth processes, aggregation, and/or tubular adhesion of renal calculi in mammalian kidneys.

Elemental mapping analysis of recurrent calcium oxalate human kidney stones

Elemental maps from a series of recurrent calcium oxalate kidney stones were obtained by PIXE with 3 MeV protons, using the nuclear microprobe at Faure. Trace elemental patterns in the stones were identified. Good positive correlations between Mn, Fe, Cu, Zn and Sr relative to Ca were identified. These correlations showed two types of distributions which could be attributed to the COM or COD phase-matrix framework. Some trace elements such as As, Se, Br and Pb were distributed homogeneously in the scanned micro-regions and possibly deposited as single ion-entities in the mixed stone matrix. It is concluded that micro-PIXE can provide useful data for deducing the mechanisms by which kidney stones are induced and how they grow.

Lithotripsy of Urinary Calculi by Tunable Pulsed Dye Lasers: A Randomized in Vitro Study

Pulsed dye laser lithotripsy has been used in the treatment of urinary calculi. We compared the efficacy of 2 pulsed dye lasers with different pulse durations in lithotripsy. A total of 20 pairs of human kidney stones was matched by size and composition, and randomized for laser lithotripsy under identical in vitro conditions. Each stone received 150 shocks at sequential energy settings between 40 and 140mJ. while in a laser fiber compatible stone basket until complete fragmentation occurred. Stone fragments were separated by size and weighed. We found that the laser with the shorter pulse duration fragmented stones with less total energy and produced fewer fragments greater than 3.35mm. The differences were statistically significant.

Determination of rare earth and other trace element abundances in human kidney stones and brain tissue by instrumental neutron activation analysis

We have used INAA to analyze more than 30 minor and trace elements in 10 human kidney stones (phosphate and oxalate types). In addition we also analyzed human brain tissue samples for trace elements by INAA to determine the limitations of the method. Samples were taken from the temporal and frontal cortex of the brain of a patient that suffered from dialysis encephalopathy (where an increased Al content is expected), as well as a number of control samples. Trace elements were analyzed to study possible compositional differences other than the Al content. The analyses were done using large volume HPGe detectors; because of the low abundances, accuracy and precision vary between 3–80% for individual elements. We found a difference between the rare earth element (REE) patterns for apatite and oxalate kidney stones, and a fractionation compared to typical REE contents in plants. For the brain samples there is evidence for differences between the dialysis patient and the control samples not only for Al, but also for some other elements including the REEs, but most differences are minimal, and may not be significant.

Time-domain computations of one-dimensional elastic waves in liquids, solids and ferroelectric ceramics

Computational solutions of linear-elastic wave equations are usually executed with frequency-domain algorithms; however, time-domain methods offer significant advantages in speed and simplicity. In this work, a time-domain algorithm is developed for one-dimensional problems in rectangular, cylindrical, and spherical coordinates. The result is simultaneously a finite-difference and method-of-characteristics algorithm. For most materials, the algorithm is explicit — for a given time, the solution at a particular position depends only upon solutions at earlier times. The exceptions are the ferroelectric ceramics which are an important class of electromechanical transducers. For these materials, the algorithm is implicit — for a given time, the solution at a particular position within the ceramic depends not only upon solutions at earlier times but also upon the current solutions at all other positions within the ceramic. Application of the algorithm is demonstrated for a variety of problems. Solutions are compared to the conventional finite-difference method, the conventional method of characteristics, and the Laplace transform method. Practical applications include the analysis of a lithotripter tool for fragmenting human kidney stones, and an acoustic logging tool for measuring the diameter and thickness of well casing.

Concentrations of rare earth elements in human brain tissue and kidney stones determined by neutron activation analysis

Determinations of rare earth element (REE) contents in biological (especially human) samples are sparse. The REEs are mainly incorporated into the human body via ingestion of (predominantly) food and by inhalation of dust particles, and are mostly excreted. A small amount may enter the blood stream through ion exchange, and can be deposited in the organs. Because of the low contents of the REEs in plasma and urine we measured REE concentrations in freeze-dried human brain tissue and in kidney stones. The measurements were carried out by neutron activation analysis, and yielded concentrations for up to nine REEs in each sample. We found that there is some difference between the REE patterns for apatite and oxalate kidney stones, and that the REEs are fractionated compared with typical REE contents in plants.

Fracture strength of human gallstones

Extracorporeal shock-wave lithotripsy (ESWL) is currently being evaluated as a treatment for symptomatic gallstones in the USA. It was first used to treat kidney stones in humans approximately 10 years ago, and now 85% of all kidney stones can be treated with this method [1]. Although ESWL can efficiently fragment gallstones, rendering them more amenable to dissolution therapy with oral bile acid therapy [2], methyl-ten-butyl ether (MTBE) [3] or Monooctanoin [4], at present it is successfully used only in a select group of patients. Nevertheless, shock-wave therapy remains a viable treatment for gallstones, particularly for those patients who prefer non-surgical treatment or for those who are physically unfit for surgery. Cholesterol is the major component of most gallstones found in the USA and Europe, the remaining components being calcium bilirubinate, calcium carbonate and mixed bile pigments. Only patients who are suspected to have cholesterol gallstones (defined as 70% cholesterol by weight) [5] are being treated with ESWL in order that the remaining fragments be dissolved. It is estimated that 10-25% of all people suffering from cholelithiasis (gallstone disease) can be successfully treated by ESWL [6]. With this in mind, some lithotripter manufacturers are attempting to develop machines that may treat both kidney stones and gallstones. The mechanical properties of these stones, however, are very different. This work was aimed at determining the fracture strength of human gallstones and investigating the effect of cholesterol content on this fracture strength. There are very few published data on the mechanical properties of gallstones. In one study two gallstones were tested by diametral compression [7]. These stones had fracture strengths of 0.23 MPa (33 lb in.-2) and 0.31 MPa (44 lb in.-2). In comparison, similar tests performed on kidney stones yielded fracture strengths ranging from 0.45 to 1.54MPa (65 to 2241bin. -2) [8]. In testing both kidney stones and gallstones, completely brittle behaviour of the stones was observed. These stones had been dried and rehydrated before testing. The present work serves to extend the determination of fracture strength of gallstones by diametral compression testing and to determine any correlation of cholesterol content with this fracture strength. Gallstones cannot readily be formed into standard tensile test samples for use with normal tensile testing machines. However, one test, the diametral compression test (sometimes called the Brazilian

Measurement of uranium in human teeth and kidney stones with the fission track technique

The measurement of uranium in human teeth and kidney stones has been carried out by using the fission track activation technique. In this determination 2759 and 2205 absolute counts of tracks /for standard: 6940 and 1556/ for teeth samples and 1689 tracks /for standard: 1446/ for kidney stone samples have been made, respectively. The results obtained by this technique are the following: Xtooth/1/=/0.227±0.006/ ppm, Xtooth/2/=/0.143±0.007/ ppm and Xkidney=/0.568±0.020/ ppm. The experimental method is described and the results discussed.

Geographical trends of carbon and sulphur isotope abundances in human kidney stones

δ 13C values and δ 34S values in human kidney stones range from −24 to −10 and −10 to + 20 %., respectively, and depend upon geographical location. Although the distributions overlap, the mean δ 13C values in oxalate stones from North America become less negative with decreasing latitude. For Mexico and Hawaii, the distributions appear to be bimodal. Uric acid stones are generally enriched in 13C by up to 7%. in comparison to oxalates from the same location, whereas cystine stones tend to span the ranges of both stone types. The geographical trends can be explained by the relative proportions of dietary carbon derived ultimately from plants undergoing various established photosynthetic mechanisms (C 3, C 4, CAM). The differences among the various major stone types may reflect isotope fractionation during biochemical conversions. Exogenic oxalates and uric acid are considered to have little role in precipitating the respective minerals. Whereas, the currently available C isotope data support this contention, more data are desirable, particularly for ingested oxalates. In contrast, S isotope data provide strong evidence that cystine stones are derived from ingested organo-S compounds and bear no relation to inorganic sulphate consumed by the individual. In turn, these organic-S compounds were probably derived from sulphate in the hydrosphere at lower levels in the food chain, e.g., by bacterial assimilation.

The kinetics of dissolution of calcium oxalate hydrates

The kinetics of dissolution of the monohydrate and trihydrate of calcium oxalate have been studied at temperatures from 15–50°C using a highly reproducible technique. The dissolution of both salts appears to be diffusion controlled, proceeding with rates which were proportional to the undersaturations. The activation energies were 13.0 and 16.6kJ mol-1 for the monohydrate and trihydrate, respectively. The solubilities of the hydrates in sodium and potassium chloride media were significantly different and the data in potassium chloride solutions have been used to determine a thermodynamic ion-association equilibrium constant for the KC2O4¯ ion-pair of 10 ∓ 1 M-1 at 37°C. Different preparations of calcium oxalate monohydrate were used to investigate the importance of specific surface area in controlling the rate of dissolution. It is interesting to note that seed prepared from human monohydrate kidney stone material dissolved with a markedly lower diffusional rate constant than that calculated from synthetic calcium oxalate monohydrate crystals on the basis of available specific surface area.

Calcareous Deposits in the Renal Sac of a Molgulid Tunicate

Weddellite (calcium oxalate dihydrate) and calcite (anhydrous calcium carbonate phase) are components of concretions in the renal sac of the ascidian tunicate Molgula manhattensis. The presence of weddellite along with urate in the concretions suggests a resemblance to human kidney stones, although, unlike the latter, the concretions in Molgula do not seem to be pathologic deposits.

Influence of sodium on calcium transport by the rat small intestine.

Influence of sodium on calcium transport by the rat small intestine.

LOCALIZATION OF UROMUCOID IN HUMAN KIDNEY AND IN SECTIONS OF HUMAN KIDNEY STONE WITH THE FLUORESCENT ANTIBODY TECHNIQUE

Fluorescent labeled antibodies were used for the demonstration of uromucoid. This urine specific mucoprotein is demonstrably present only in the epithelial cells of the proximal segments of the normal human renal tubules and in the matrix of human kidney stones of all the common crystalline compositions.