Human Kidney Stones Research Articles

Evidence for Trapped Surface Bubbles as the Cause for the Twinkling Artifact in Ultrasound Imaging

The mechanism of the twinkling artifact (TA) that occurs during Doppler ultrasound imaging of kidney stones was investigated. The TA expresses itself in Doppler images as time-varying color. To define the TA quantitatively, beam-forming and Doppler processing were performed on raw per channel radio-frequency data collected when imaging human kidney stones in vitro. Suppression of twinkling by an ensemble of computer-generated replicas of a single radio frequency signal demonstrated that the TA arises from variability among the acoustic signals and not from electronic signal capture or processing. This variability was found to be random, and its suppression by elevated static pressure and return when the pressure was released suggest that the presence of bubbles on the stone surface is the mechanism that gives rise to the TA.

2aBA6. Bubbles trapped on the surface of kidney stones as a cause of the twinkling artifact in ultrasound imaging.

A twinkling artifact (TA) associated with urinary calculi has been described as rapidly changing colors on Doppler ultrasound. The purpose of this study was to investigate the mechanism of the TA. Doppler processing was performed on raw per channel radio-frequency data collected when imaging human kidney stones in degassed water. Suppression of twinkling by an ensemble of computer generated replicas of a single received signal demonstrated that the TA arises from variability among the acoustic signals and not from electronic signal processing. This variability was found to be random in nature, and its suppression by elevated static pressure, and its return when the pressure was released, suggests that the presence of surface bubbles on the stone is the mechanism of the TA. Submicron size bubbles are often trapped in crevices on solid objects, but the presence of these bubbles in vivo is unexpected. To further check this mechanism under conditions identical to in vivo, stone-producing porcine kidneys were harvested en bloc with a ligated ureter and then placed into a pressure chamber and imaged at elevated atmospheric pressure. The result was similar to in vitro. Work supported by NIH DK43881, DK092197, RFBR 11-02-01189, 12-02-00114, and NSBRI through NASA NCC 9-58.

Differentiation of Calcium Oxalate Monohydrate and Calcium Oxalate Dihydrate Stones Using Quantitative Morphological Information from Micro-Computerized and Clinical Computerized Tomography

We differentiated calcium oxalate monohydrate and calcium oxalate dihydrate kidney stones using micro and clinical computerized tomography images. A total of 22 calcium oxalate monohydrate and 15 calcium oxalate dihydrate human kidney stones were scanned using a commercial micro-computerized tomography scanner with a pixel size of 7 to 23 μm. Under an institutional review board approved protocol, image data on 10 calcium oxalate monohydrate and 9 calcium oxalate dihydrate stones greater than 5 mm were retrieved from a total of 80 patients who underwent clinical dual energy computerized tomography for clinical indications and had stones available for infrared spectroscopic compositional analysis. Micro and clinical computerized tomography images were processed using in-house software, which quantified stone surface morphology with curvature based calculations. A shape index was generated as a quantitative shape metric to differentiate calcium oxalate monohydrate from calcium oxalate dihydrate stones. Statistical tests were used to test the performance of the shape index. On micro-computerized tomography images the shape index of calcium oxalate monohydrate and calcium oxalate dihydrate stones significantly differed (ROC curve AUC 0.92, p <0.0001). At the optimal cutoff sensitivity was 0.93 and specificity was 0.91. On clinical computerized tomography images a significant morphological difference was also detected (p = 0.007). AUC, sensitivity and specificity were 0.90, 1 and 0.73, respectively. On micro and clinical computerized tomography images a morphological difference was detectable in calcium oxalate monohydrate and calcium oxalate dihydrate stones larger than 5 mm. The shape index is a highly promising method that can distinguish calcium oxalate monohydrate and calcium oxalate dihydrate stones with reasonable accuracy.

Qualitative Analysis of Human Kidney Stone Samples Using Biochemical Tests and by X-Ray Diffraction Technique

Kidney stone disease is a common health problem in industrialized nations. A better understanding of the physio-chemical principles underlying the formation of kidney stone has led to a need for more precise information on the chemical composition of stones. A combined qualitative procedure for the chemical analysis of renal stone which is suitable for routine use is presented. The procedure involves two qualitative tests i.e. biochemical tests and X-ray diffraction. Through these tests we are determining the elements present in the renal stone and we can suggests people to avoid those food stuffs in which the elements present similar to kidney stone so that recurrence in future will be avoided.

Association between Human Prothrombin Variant (T165M) and Kidney Stone Disease

We previously reported the association between prothrombin (F2), encoding a stone inhibitor protein - urinary prothrombin fragment 1 (UPTF1), and the risk of kidney stone disease in Northeastern Thai patients. To identify specific F2 variation responsible for the kidney stone risk, we conducted sequencing analysis of this gene in a group of the patients with kidney stone disease. Five intronic SNPs (rs2070850, rs2070852, rs1799867, rs2282687, and rs3136516) and one exonic non-synonymous single nucleotide polymorphism (nsSNP; rs5896) were found. The five intronic SNPs have no functional change as predicted by computer programs while the nsSNP rs5896 (c.494 C>T) located in exon 6 results in a substitution of threonine (T) by methionine (M) at the position 165 (T165M). The nsSNP rs5896 was subsequently genotyped in 209 patients and 216 control subjects. Genotypic and allelic frequencies of this nsSNP were analyzed for their association with kidney stone disease. The frequency of CC genotype of rs5896 was significantly lower in the patient group (13.4%) than that in the control group (22.2%) (P = 0.017, OR 0.54, 95% CI 0.32–0.90), and the frequency of C allele was significantly lower in the patient group (36.1%) than that in the control group (45.6%) (P = 0.005, OR 0.68, 95% CI 0.51–0.89). The significant differences of genotype and allele frequencies were maintained only in the female group (P = 0.033 and 0.003, respectively). The effect of amino-acid change on UPTF1 structure was also examined by homologous modeling and in silico mutagenesis. T165 is conserved and T165M substitution will affect hydrogen bond formation with E180. In conclusion, our results indicate that prothrombin variant (T165M) is associated with kidney stone risk in the Northeastern Thai female patients.

Differentiation of Kidney Stones Using Dual-Energy CT With and Without a Tin Filter

The aim of this in vitro study was to examine the capability of three protocols of dual-energy CT imaging in distinguishing calcium oxalate, calcium phosphate, and uric acid kidney stones. A total of 48 calcium oxalate, calcium phosphate, and uric acid human kidney stone samples were placed in individual containers inside a cylindric water phantom and imaged with a dual-energy CT scanner using the following three scanning protocols of different combinations of tube voltage, with and without a tin filter: 80 and 140 kVp without a tin filter, 100 and 140 kVp with a tin filter, and 80 and 140 kVp with a tin filter. The mean attenuation value (in Hounsfield units) of each stone was recorded in both low- and high-energy CT images in each protocol. The dual-energy ratio of the mean attenuation values of each stone was computed for each protocol. For all three protocols, the uric acid stones were significantly different (p < 0.001) from the calciferous stones according to their dual-energy ratio values. For differentiating calcium oxalate and calcium phosphate stones, the difference between their dual-energy ratio values was statistically significant, with different degrees of significance (range, p < 0.001 to p = 0.03) for all three protocols. On the basis of the values of the area under receiver operating characteristic curve (AUC) of calcified stone differentiation, the three protocols were ranked in the following order: the 80- and 140-kVp tin filter protocol (AUC, 0.996), the 100- and 140-kVp tin filter protocol (AUC, 0.918), and the 80- and 140-kVp protocol (AUC, 0.871). The tin filter added to the high-energy tube and the use of a wider dual-energy difference are important for improving the stone differentiation capability of dual-energy CT imaging.

Adhesion Properties of Uric Acid Crystal Surfaces

Two key steps in kidney stone formation--crystal aggregation and attachment to renal tissues--depend on the surface adhesion properties of the crystalline components. Anhydrous uric acid (UA) is the most common organic crystalline phase found in human kidney stones. Using chemical force microscopy, the adhesion force between various functional groups and the largest (100) surface of UA single crystals was measured in both aqueous solution and model urine. Adhesion trends in the two solutions were identical, but were consistently lower in the latter. Changes in the solution ionic strength and pH were also found to affect the magnitude of the adhesion. UA surfaces showed the strongest adhesion to cationic functionalities, which is consistent with ionization of some surface uric acid molecules to urate. Although hydrogen-bonding and van der Waals interactions are usually considered to be dominant forces in the association between neutral organic compounds, this work demonstrates that electrostatic interactions can be important, particularly when dealing with weak acids under certain solution conditions.

1709 IMPROVED DETECTION OF KIDNEY STONE TWINKLING USING AUTOREGRESSIVE SIGNAL PROCESSING METHOD

You have accessJournal of UrologyStone Disease: New Technology/SWL, Ureteroscopic or Percutaneous Stone Removal II1 Apr 20121709 IMPROVED DETECTION OF KIDNEY STONE TWINKLING USING AUTOREGRESSIVE SIGNAL PROCESSING METHOD John Kucewicz, Barbrina Dunmire, and Michael R. Bailey John KucewiczJohn Kucewicz Seattle, WA More articles by this author , Barbrina DunmireBarbrina Dunmire Seattle, WA More articles by this author , and Michael R. BaileyMichael R. Bailey Seattle, WA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.1646AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The Twinkling Artifact (TA) is the rapidly changing, random pattern of colors on and deep to kidney stones during ultrasound color Doppler imaging. The potential clinical benefit of TA to urology is well documented, but the use of TA is not without limitations. The origin of TA is not well understood, it appears to be influenced by multiple system settings, and without a specific knob to control it, twinkling can be intermittent. Furthermore, twinkling can be misinterpreted as true blood flow reducing its sensitivity to the detection of stones. The objective of this work is to develop signal processing methods that are highly sensitive to kidney stones and insensitive to blood flow. METHODS Conventional Doppler autocorrelation (AC) methods are optimized to detect blood flow based primarily on backscattered power and Doppler frequency shift. Tissue is typically high power and low frequency, and blood flow is typically low power and high frequency. Twinkling is characteristically high power with broad frequency content, i.e. high amplitude noise. An autoregressive(AR) method has been developed that is able to differentiate between narrowband, coherent signals from tissue and blood flow and broadband, incoherent signals characteristic of TA. Ultrasound data were collected from a tissue phantom containing a human ex-vivo kidney stone and a 5mm flow channel. Water with cellulose was pumped through the flow channel to simulate blood flow. Ultrasound data prior to any Doppler-specific signal and image processing were collected with an Ultrasonix RP (Ultrasonix Medical Corporation, Canada) while varying acoustic output and receiver gain. Twinkling was measured using an AC Doppler method and our AR method. RESULTS AR power was typically 0 to 2dB less from the stone and 5 to 10 dB less from the flow channel relative to power measured by AC. The relative difference between the AR and AC powers was able to differentiate stone twinkling and flow with a sensitivity of 0.94 and a specificity of 0.89. CONCLUSIONS Twinkling is a potentially useful method of imaging kidney stones with ultrasound but its value will remain limited without an imaging mode optimized for the unique ultrasound signals that typify stones. Autoregression is a simple, computationally efficient alternative signal processing method to conventional autocorrelation processing that addresses the limitation of ambiguity between kidney stone twinkling and true blood flow. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e689-e690 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information John Kucewicz Seattle, WA More articles by this author Barbrina Dunmire Seattle, WA More articles by this author Michael R. Bailey Seattle, WA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

2082 STRONTIUM SUBSTITUTION FOR CALCIUM IN LITHOGENESIS

You have accessJournal of UrologyStone Disease: Basic Research I1 Apr 20122082 STRONTIUM SUBSTITUTION FOR CALCIUM IN LITHOGENESIS Sarah D. Blaschko, MD Lawrence Flechner, MD Gyorgy Snell, PhD Thomas Chi, MD Joe Miller, MD Sirine Fakra, andMS Marshall L. StollerMD Sarah D. BlaschkoSarah D. Blaschko San Francisco, CA More articles by this author , Lawrence FlechnerLawrence Flechner San Francisco, CA More articles by this author , Gyorgy SnellGyorgy Snell Berkeley, CA More articles by this author , Thomas ChiThomas Chi San Francisco, CA More articles by this author , Joe MillerJoe Miller San Francisco, CA More articles by this author , Sirine FakraSirine Fakra Berkeley, CA More articles by this author , and Marshall L. StollerMarshall L. Stoller San Francisco, CA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2248AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Strontium has two available valence electrons for chemical bonding and is positioned in the same column of the periodic table as calcium. This chemical similarity enables the replacement of calcium by strontium in biological processes. Strontium has long been used as a substitute for calcium when testing calcium absorption in the gut and calcium filtration by the kidney and exists as four stable isotopes. Ratios of these isotopes have been used to identify the origins of plants, animals, and soil. Incorporation of strontium into human bone and teeth has been studied extensively, however little research has been performed on the incorporation of strontium into urinary calculi. We utilized synchrotron based X-ray fluorescence (XRF) and X-ray absorption (XAS) techniques to examine the presence of strontium in different types of human kidney stones. We postulate that the presence of strontium in urolithiasis may be utilized to help better understand early calcium-based stone pathogenesis. METHODS Multiple unique human stone samples were obtained via consecutive percutaneous nephrolithotomies/ureteroscopies and a portion was sent for standard laboratory analysis with Fourier Transform Infrared Spectroscopy (FTIR). XRF and XAS measurements were carried out at the Advanced Light Source synchrotron radiation facility at the Lawrence Berkeley National Laboratory to examine the presence, spatial distribution and speciation of strontium in each stone sample. RESULTS Traditional kidney stone analyses identified calcium oxalate, calcium phosphate, uric acid, and cystine stones. XRF measurements identified strontium in all stone types except for pure cystine. XRF elemental mapping of the samples revealed co-localization of calcium and strontium. XAS measurements of the calcium phosphate stone showed that strontium is predominately present as strontium apatite. CONCLUSIONS Advanced X-ray fluorescence methods identified strontium in all calcium based stones and is present as strontium apatite. This finding may be critical as apatite is often thought to be the initial nidus for calcium stone formation. Strontium is overlooked with standard laboratory stone analyses; substitution for calcium can be reliably identified in stones from multiple calcium-based stone formers with different stone compositions and offers insight into early events in lithogenesis. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e839 Peer Review Report Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Sarah D. Blaschko San Francisco, CA More articles by this author Lawrence Flechner San Francisco, CA More articles by this author Gyorgy Snell Berkeley, CA More articles by this author Thomas Chi San Francisco, CA More articles by this author Joe Miller San Francisco, CA More articles by this author Sirine Fakra Berkeley, CA More articles by this author Marshall L. Stoller San Francisco, CA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Accuracy of kidney stone size in conventional ultrasound Bmode imaging

The objective of this study was to determine the accuracy of conventional ultrasound imaging in sizing kidney stones, since this can be a determining factor in the treatment protocol for fragments on the order of 5 mm. Ex-vivo human kidney stones 3 to 12 mm were imaged in a water bath at depths from 6 to 10 cm using a Philips HDI5000 and Versonics software-based ultrasound system with the C4-2 transducer. Stone sizes were estimated offline a) manually by a sonographer and b) through an automated contrast based edge detection algorithm. Stone size was consistently overestimated with both instruments and by both estimation methods. On average, size was overestimated by 1 to 2 mm for stones 6 cm deep, and the overestimation increased with increasing depth and system gain. The overestimation was independent of actual stone size. These results suggest there is an inherent error in conventional ultrasound that leads to overestimation of stone size. These results also validate the software-based instrument for future work toward 1) investigating the sources of overestimation and 2) testing new methods for improving the accuracy of size estimation. Work supported by NIH DK43881 and DK092197, and NSBRI through NASA NCC 9-58.

Formación de calculos renales de oxalato cálcico en mamíferos

Calcium oxalate (CaOx) is the main inorganic component of urolithiasis and is mainly present in the formation of kidney stones in humans. Additionally, oxalocalcic urolithiasis has become the most frequent type of kidney stones, for instance, oxalocalcic urolithiasis has substantially increased in dogs and cats over the last decades. In urolithiasis, urine is supersaturated with calcium and oxalate ions that promote nucleation, growth and aggregation of CaOx crystals. It is accepted that the presence of acidic macromolecules and inorganic compounds in urine is responsible not only for the molecular processes involved in lithiasis but also for the adhesion and endocytosis by renal epithelial cells. Patients with the tendency to form kidney stones may have an alteration in the structure and/or function of some inhibitors of crystallization. In the current review, we describe some general aspects of epidemiology and pathophysiology of oxalocalcic urolithiasis.

Occurrence of Nanobacteria-Like Particles in Renal Stones of a Southern Brazilian Population

Purpose: Identifying the source of stone formation in recurrent stone formers has always been a big problem. Material and Methods: In this study kidney stones from 52 patients were submitted to direct examination by scanning electronic microscopy (SEM) after manual fracture and 27 calculi were cultured in Eagle’s Minimum Essential Medium (E-MEM) and Brain-Heart Infusion (BHI) for eight weeks at 37°C in 5% CO2 atmosphere. Twenty-seven powdered and demineralized stones were suspended in sterile PBS, filtered through 0.22 m-pore-size sterile filters Millex (Millipore, Massachusetts, USA) and submitted to DNA extraction (Quiagen-Brazil). Platinum PCR SuperMIX (GIBCO-BRL), primers (Invitrogen), and Ultra Pure Water (Advanced Biotechnologies, Columbia, MD) were used for PCR (Polymerase Chain Reaction), which was generally conducted for 30 or 35 cycles with annealing of primers for 40 sec at 55°C and extension for 1 min at 72°C. Results: In 36 out 52 (69%) kidney stones it was detected the presence of biofilm coating the mineral surface of the stone when examined by SEM, consisting of coccoid particles, isolated or clustered, with diameter of 500 nm or less. Eleven out 27 (41%) kidney stone cultures produced white-colored sediment on the bottom of the tubes after eight-week incubation, revealing tiny structures similar to those observed directly by SEM. These structures were similar in size and morphology to spherical apatite particles previously observed in human kidney stones and named as nanobacteria (NB). No PCR products were observed in the samples. Conclusion: We found a strong correlation between renal stones and calcifying nanoparticles (CNP) in this study and these results open a new insight on this area to explore the etiology of stone formation. Whether NB/CNP are truly microorganisms or self-propagating mineral compounds is still controversial and its contribution, if any, in apatite nucleation and crystal growth remains uncertain.

Transmission FT-IR spectroscopic analysis of human kidney stones in the Hyderabad region of Pakistan

The purpose of the present study was to investigate the composition of kidney stones removed from human patients. Seventeen samples were collected after surgery (5 females and 12 males; age range 2 to 60 years). The samples were analyzed for composition by transmission Fourier transform infrared (FT-IR) spectroscopy. The 17 analyzed samples of kidney stones comprised 29.4% calcium oxalate, 29.4% uric acid, 29.4% calcium oxalate (CaOx)-uric acid, 5.9% phosphate, and 5.9% calcium oxalate-phosphate stones. The results of the study indicated that transmission FT-IR spectroscopy could be used as an environmentally friendly technique for rapid screening of kidney stones.

Differential analysis of human kidney stone samples using electrospray ionization mass spectrometry

Kidney stones may be caused by many factors, including ingestion of melamine for a relatively long time. The diagnosis of melamine-induced kidney stones and the understanding of how the melamine is involved in the formation of kidney stones are of practical importance. To establish a sensitive method based on widely used electrospray ionization mass spectrometry (ESI-MS) for diagnosis of melamine-induced kidney stones and to probe the differential formation of melamine-induced kidney stones at molecular levels. Human kidney stones were collected in hospital from 6 groups of patients at different ages. ESI-MS was employed as the main technique with the principal component analysis for data processing. Using principal component analysis (PCA) of the ESI-MS fingerprints, a set of 21 melamine-induced kidneystone samples and 21 uric acid derived kidney stone samples were successfully differentiated from the other groups, rendering ESI-MS method a potential platform for differential analysis of the human kidney stones of various causes at molecular levels. The experimental results also indicate that in addition to the melamine, the chemical compounds enwrapped in the melamine-induced kidney stone samples are different from other kidney stone samples. These findings suggest that ESI-MS is a useful tool for diagnosis of melamine-induced kidney stone samples and the melamine-induced kidney stone could be formed by different mechanisms. Key words: Toxicity of melamine, chemical profiling, uric acid, electrospray ionization-mass spectrometry (ESI-MS), kidney stone, melamine, principal component analysis.

Effects of water uptake on melamine renal stone formation in mice

Melamine-tainted food can induce kidney stones both in humans and animals and in domestic animals, severe cases caused acute kidney failure and death. Although increasing water intake can ameliorate kidney stone formation, its effect on melamine (Mel)-induced kidney stones has not been studied. We have analysed the effect of restricted ingestion of drinking water on melamine stone formation in mice. They were given melamine and cyanuric acid orally and received drinking water either freely or for a restricted time. Kidney stone formation and renal function were monitored. Mice receiving drinking water for a restricted 10-h period initially lost body weight, which returned to normal within 2 days. No other abnormalities were observed. Ingestion of melamine alone failed to induce kidney stones even under conditions of restricted drinking water. In mice treated with melamine together with cyanuric acid for 3 days, no renal stones were formed when the supply of drinking was normal. However, when drinking water was limited, stone formation was observed and accompanied by high levels of serum urea and creatinine. An increase in urine haemoglobin and glucose levels was also found. The administration resulted in up-regulated tissue osteopontin, kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin messenger RNA expression and macrophage infiltration. Our results indicate the importance of water intake in the formation of melamine-induced renal stone formation in the mouse and provide new information on the mechanisms of melamine stone formation.

Investigation on the effect of specular reflections from stone surface on twinkling artifact

The twinkling artifact can highlight kidney stones during ultrasound color Doppler imaging with high sensitivity for stone detection. The mechanism of the twinkling artifact is still under debate. It was reported previously that twinkling appeared distal to the echogenic reflection from the stone surface in cases with no signal saturation. [Lu etal., JASA 129(4), p. 2376]. In this report, the effect of specular reflections on twinkling was investigated. Human kidney stones (5-9 mm in length) were embedded in a polyacrylamide gel phantom. Radio-frequency (RF) data were recorded from pulse-echo ensembles using a software-programmable ultrasound system. The variability within the beamformed Doppler ensemble, which is responsible for twinkling, was traced back to the unbeamformed RF channel data to identify whether variability arose disproportionately on channels receiving the specular reflection. The results showed that the specular reflection did not saturate individual channels and that the variability was observed on most channels with similar magnitude, which indicates that the appearance of twinkling does not rely on the specular reflection from the stone surface. Instead in the beamformer, the varying signals have the appearance of arising from a point source within the stone. [Work supported by NIH DK43881, DK086371, DK092197, and NSBRI through NASA NCC 9-58.]

The beneficial effect of cynodon dactylon fractions on ethylene glycol-induced kidney calculi in rats.

To assess the beneficial effect of different fractions of Cynodon dactylon (C. dactylon) on ethylene glycol-induced kidney calculi in rats. Male Wistar rats were randomly divided into control, ethylene glycol, curative, and preventive groups. The control group received tap drinking water for 35 days. Ethylene glycol, curative, and preventive groups received 1% ethylene glycol for induction of calcium oxalate (CaOx) calculus formation. Preventive and curative subjects also received different fractions of C. dactylon extract in drinking water at 12.8 mg/kg, since day 0 and day 14, respectively. After 35 days, the kidneys were removed and examined for histopathological findings and counting the CaOx deposits in 50 microscopic fields. In curative protocol, treatment of rats with C. dactylon N-butanol fraction and N-butanol phase remnant significantly reduced the number of the kidney CaOx deposits compared to ethylene glycol group. In preventive protocol, treatment of rats with C. dactylon ethyl acetate fraction significantly decreased the number of CaOx deposits compared to ethylene glycol group. Fractions of C. dactylon showed a beneficial effect on preventing and eliminating CaOx deposition in the rat kidney. These results provide a scientific rational for preventive and treatment roles of C. dactylon in human kidney stone disease.

High Zn content of Randall's plaque: A μ-X-ray fluorescence investigation

Kidney stone disease, or nephrolithiasis, is a common ailment. Among the different risk factors usually associated with nephrolithiasis are dehydration, metabolic defects (especially with regard to calcium and oxalate). The presence of a mineral deposit at the surface of the renal papilla (termed Randall's plaque) has all been recently underlined. Of note, Randall's plaque is made of the calcium phosphate, carbapatite, and serves as a nucleus for kidney stone formation. The process by which apatite nanocrystals nucleate and form Randall's plaque remains unclear. This paper deals with the possible relationship between trace elements and the formation of this mineral. The investigation has been performed on a set of Randall's plaques, extracted from human kidney stones, through μ-X-ray diffraction and μ-X-ray fluorescence analyses in order to determine the chemical composition of the plaque as well as the nature and the amount of trace elements. Our data provide evidence that Zn levels are dramatically increased in carbapatite of RP by comparison to carbapatite in kidney stones, suggesting that calcified deposits within the medullar interstitium are a pathological process involving a tissue reaction. Further studies, perhaps including the investigation of biomarkers for inflammation, are necessary for clarifying the role of Zn in Randall's plaque formation.

PREVENTIVE EFFECT OF CYNODON DACTYLON AGAINST ETHYLENE GLYCOL-INDUCED NEPHROLITHIASIS IN MALE RATS

Objective: This study was carried out to investigate the prev entive effects of hydroalcoholic extract of Cynodon dactylon (C.dactylon) roots on calcium oxalate calculi in rat. Materials and Methods: 24 Wistar rats were randomly divided into 4 groups : group A received tap drinking water while, Groups B, C, and D received 1 % ethylene glycol daily for 28 days. Rats in groups C and D received ethanolic extract of C.dactylon at doses equivalent to 3.2 mg/kg and 12.6 mg/kg of root powder, respectively in drinking wate r from day 0 to day 28. Urine and blood were collected on days 0 and 28 and analyzed for biochemical elements. After 28 days, the kidneys were removed and prepared for histological evaluation of calcium oxalate deposits (CaOx). Results: The number of CaOx deposits in 10 microscopic fields of kidney slices in group B was 24.5 ± 4.40 which was significantly higher than group A (p<0.001). In group C, the number of deposits was significantly lower than group B. The weight of the kidneys was increased in group B vs group A (p<0.05). However, C.dactylon was able to decrease the weight of kidneys in grou p C (p<0.05). Urine oxalate level decreased in nephrolithiatic rats tre ated with the extract. Conclusion: This study showed that C. dactylon extract was able to reduce the growth of urinary stones in the rat. Therefore, the beneficial action of C.dactylon extract on human kidney stones may be suggested. However, further studies must clarify th e mechanism.

7,9-Bis(hydroxymethyl)-7H-purine-2,6,8(1H,3H,9H)trione

The structure of the title uric acid derivative, C7H8N4O5, from human kidney stones, is characterized by the C and O atoms of one of the two hy­droxy­methyl groups being disordered nearly equally over three different sites. In the crystal, mol­ecules are connected by a three-dimensional hydrogen-bonding scheme though they look stacked in planes nearly parallel to (04).