Triamterene and renal stone formation: The influence of triamterene and triamterene stones on calcium oxalate crystallization

Summary A constant composition method has been used to compare the effects of triamterene renal stone material, synthetic triamterene precipitates, and soluble triamterene on the nucleation and crystallization kinetics of calcium oxalate in aqueous solutionin vitro. Crystallization studies have been carried out with the concentrations of calcium and oxalate ions maintained constant by the potentiometrically controlled addition of concentrated reagent solutions containing these ions. Triamterene renal stones were found to be much less effective than synthetic triamterene towards promoting the nucleation and crystallization of calcium oxalate from supersaturated solution. Renal stones composed of triamterene and matrix did not significantly enhance the deposition of calcium oxalate compared to nonseeded controls. The triamterene stones were also found to be ineffective in promoting calcium oxalate crystallization compared to other precipitates thought to be involved in the etiology of stone disease such as calcium hydroxyapatite. For stones of mixed triamterene/calcium oxalate composition, the enhancement of the nucleation and crystallization of calcium oxalate was directly related to the calcium oxalate content of the stone seed material. The presence of soluble triamterene or its metabolites in solution did not influence the crystallization kinetics of pure calcium oxalate seed materials. The results of this study indicate that triamterene in stones does not significantly contribute to further stone development through the enhancement of calcium oxalate crystallization processes.     

Kinetic factors influencing the dissolution behavior of calcium oxalate renal stones: A constant composition study

Summary A constant composition method has been used to examine the dissolution kinetics of calcium oxalate renal stones over a wide range of undersaturationin vitro. Demineralization experiments have been carried out with the concentrations of calcium and oxalate ions and ionic strength (hence the solution undersaturation) held constant by the potentiometrically controlled addition of medium electrolyte solution as diluent, triggered by a calcium ion electrode. Kinetic data for renal stones have been compared with results obtained for synthetic calcium oxalate. In addition, constant composition results have been directly compared with results obtained using conventional dissolution methods for both calculi and synthetic calcium oxalate. Overall, calcium oxalate renal stones exhibited markedly different kinetic dissolution behavior as compared with synthetic controls. The renal stone samples dissolved more slowly at all undersaturations, exhibited increased kinetic orders of reaction, and showed reduced sensitivity to solution hydrodynamics. Stones composed of mixed hydrates of calcium oxalate (mono- and di-) came to dihydrate equilibrium in conventional experiments and underwent net dissolution in solutions supersaturated to monohydrate under constant composition conditions. No conversion of di- to monohydrate was observed under these experimental conditions. These results indicate that stone dissolution is strongly influenced by adsorbed inhibitors, presumaly including matrix components, which may complicate efforts to develop systemic and/or irrigation measures effective forin situ solubilization.     

Calcium phosphate: an important crystal phase in patients with recurrent calcium stone formation?

Summary Stone and urine composition were analysed in 75 men and 40 women with recurrent calcium oxalate stone disease (group R) and in 48 men and 19 women who had formed only one calcium-oxalate-containing stone (group S). Patients who had developed stones with a large fraction of calcium phosphate were significantly more frequent in group R than in group S. There was furthermore a higher excretion of calcium and higher calcium oxalate supersaturation levels in patients with stones containing more than 25% calcium phosphate. It was concluded from these observations that the calcium phosphate content of renal stones might be a useful factor in predicting the future course of the disease.     

Studies on the morphology of human uric acid stones

Summary Human uric acid renal stones are easily distinguished from other urinary calculi by their globular or spherical shape, their colour and their hardness. Investigations of uric acid crystals grown in the presence of a variety of pigments indicate that a disordered layer structure of the uric acid dihydrate is responsible for the colour of such crystals, caused by the inclusion of pigment molecules into the crystal lattice. This in turn may help to explain the other special properties of uric acid stones.     

Calcium oxalate crystallization kinetics at different concentrations of human and artificial urine, with a constant calcium to oxalate ratio

The effect of in vitro dilution of artificial urine or human urine on the crystallization of calcium oxalate was examined in a mixed suspension, mixed product removal crystallization system. Direct growth inhibition by components of artificial urine was not significant and supersaturation was the dominant factor in determining crystal nucleation and growth rates. Dilution of human urine caused a decrease in crystal growth rate that was independent of the input calcium and oxalate concentrations, suggesting that dilution of growth inhibitors could be physiologically more important than any reduction in supersaturation. This loss of growth inhibition was counteracted by a reduction in nucleation promotion, with the net effect that the mass of crystals declined. Correlation of crystallization measurements with urinary concentration (osmotic pressure) confirmed these observations, with a negative relationship for growth rate and a positive relationship for nucleation rate and suspension density. Increasing the concentration of urine shifts the crystallization balance from low nucleation/high growth to high nucleation/low growth. Calcium oxalate crystalluria in healthy urine is therefore less likely at early stages of urine development in the nephron and the likelihood can be further reduced by increased fluid output. Our results suggest that lowering the heterogeneous nucleation activity by dilution is more than sufficient to override the loss of growth inhibition. Received: 2 September 1998 / Accepted: 22 January 1999     

Measurement of the risk of calcium oxalate crystallization in urine

Summary The risk of calcium crystallization (CaOx-CR) in urine was analyzed by means of crystal counting following standardized addition of oxalate. CaOx-CR was determined in 24h urine samples from 21 stone formers and 26 normal subjects following dilution of urine to a creatinine concentration of 5 mol per ml. The mean (±SD) CaOx-CR was in stone formers 1.42±0.57 and in normal subjects 1.29±0.40. CaOx-CR was also analyzed in 16 fresh urine samples diluted to 80 per cent of the original concentration whereby values between 0.36 and 3.6 were recorded. There was a good correlation between CaOx-CR and estimates of the ion-activity product of CaOx, both in urine diluted to 5 mol of creatinine per ml and in 80 per cent diluted urine. It ist suggested that the method described is of value for evalution and follow up of patients with CaOx urolithiasis.     

Chemical factors governing the state of saturation towards brushite and whewellite in urine of calcium stone formers

Summary Variations of urinary pH and concentrations of calcium, phosphate, oxalate, magnesium and citrate have been produced by 4 different diets given to 19 idiopathic calcium stone formers. The state of saturation towards whewellite and brushite was directly measured in the 76 urine samples by equilibration with the corresponding salts and was compared to chemical constituents by regression analyses. The state of saturation towards calcium oxalate monohydrate was significantly governed only by the urinary oxalate concentration, and a soluble oxalate fraction not contributing to calcium oxalate chelation was demonstrated. The state of saturation towards brushite was exclusively determined by urinary calcium and pH, the latter below 5.5 showing a high influence on brushite solubility.     

草酸和一水草酸钙结晶对人肾小管上皮细胞的影响

目的 观察草酸和一水草酸钙结晶对体外培养的人肾小管上皮细胞(HK-2)的毒性作用和蛋白表达的影响,探讨上皮细胞受损在肾结石形成过程中的可能作用.方法 体外培养正常人HK-2细胞至长满后,换成无血清培养基,加入草酸至不同终浓度,显微镜下观察结晶的形成及其对细胞的粘附.收集结晶以傅立叶红外光谱仪(FT-IR)分析其成分.CCK-8试剂盒检测1、2、5和10mmol/L草酸分别作用4、12和24 h后对HK-2细胞的毒性反应,Bradford法检测HK-2细胞表达总蛋白量的变化.结果草酸加入含Ca2+的DMEM培养基后,数分钟内显微镜F即可见结晶形成并粘附于细胞表面.FT-IR分析表明结晶成分为一水草酸钙.草酸和一水草酸钙对HK-2的毒性作用呈明显浓度依赖性,但在1～10 mmol/L草酸浓度下毒性作用不随时间延长而增加.1、2、5mmol/L草酸作用12 h和对照组HK-2表达蛋白量分别为(358±51)、(365±43)、(328±52)和(329±60)mg/L,P值均＞0.05,而10 mmol/L草酸作用12 h后,HK-2表达蛋白量为(264±76)mg/L,显著低于对照组(P＜0.05).结论 草酸和一水草酸钙可对正常人HK-2细胞产生毒性损伤,造成细胞表达蛋白的改变,可能在肾结石的形成中起重要作用.     

Estimated levels of supersaturation with calcium phosphate and calcium oxalate in the distal tubule

Approximate estimates of the ion-acitivity products of calcium phosphate and calcium oxalate in distal tubular urine were derived from the 16-h urinary excretion of calcium, oxalate, citrate, magnesium and phosphate. Urine variables were obtained from 96 normal subjects and 277 calcium stone formers and the calculations were carried out with iterative approximation using the EQUIL2 program. With respect to other ions of importance for the ion-activity products, the urine was assumed to have a fixed composition with pH 6.45. Significantly higher ion-activity products of both calcium phosphate and calcium oxalate were recorded in stone formers. It was concluded that diurnal variations in urine composition and pH might result in peaks of calcium phosphate supersaturation in distal tubular urine whereby a crystallization can occur. In association with abnormalities in terms of promotion and inhibition of calcium salt crystallization, such a precipitation can be of importance for the subsequent formation of calcium renal stones.     

Crystallisation properties in stone forming and normal subjects' urine diluted using a standardised procedure to match the composition of urine in the distal part of the distal tubule and the middle part of the collecting duct

Using a standardised procedure, we assessed the crystallisation properties of calcium phosphate in urine with a composition matching that in the distal part of the distal tubules (DTd) and of calcium oxalate in urine with a composition matching that in the mid-collecting duct (CDm). We used 8-h urine samples collected between 2200 h and 0600 h with sodium azide as preservative. Urine from ten patients with recurrent CaOx stone formation and from ten normal subjects was used for the measurements. The DTd and CDm samples were obtained by diluting the voided 8-h urine to 3000 ml and 1750 ml per 1.73 m² body surface area, respectively. The nucleation was studied in DTd urine following supersaturation with CaP. The crystal size distribution was assessed with a Coulter counter both following supersaturation of DTd urine with CaP and of CDm urine with CaOx. The crystallisation of CaP in DTd urine as well as that of CaOx in CDm urine, in the presence of CaP crystals that had been precipitated in DTd urine, was measured with the isotope technique. The inhibition of CaOx and brushite crystal aggregation in standardised diluted aliquots of DTd and CDm urine was assessed spectrophotometrically as the rate of sedimentation. There was a slightly increased sedimentation rate and a lower initial absorbance in DTd urine from stone formers supersaturated with CaP. Although these findings might reflect a state of increased crystal aggregation in stone formers' urine, this could not be confirmed by crystal size measurements in the Coulter counter. The inhibition of brushite crystal aggregation in DTd urine was significantly in stone formers' urine than in normal subjects' urine (P < 0.001). Moreover, all inhibition values in DTd samples from stone formers were negative, suggesting a promoter effect on crystal aggregation. The inhibition of CaOx crystal aggregation in CDm urine also was significantly higher in CDm urine from normal subjects than in CDm urine from stone formers (P < 0.05). For all other variables the level was similar when urine samples from the two groups were compared. Although this series of crystallisation assessments was carried out on a small number of standardised diluted urine samples only, the results nevertheless emphasise a defect in aggregation inhibition as one important determinant for an abnormal calcium salt crystallisation in patients with recurrent stone formations. This difference obviously includes aggregation of both CaP crystals in DTd urine and CaOx crystals in CDm urine. The results also show that assessment of crystallisation properties of this kind can be carried out in standardised, diluted 8-h night urine samples, which accordingly can be used in the routine work-up of patients with calcium stone disease. Such an approach might prove useful in order to get information on the combined effects of the driving force of supersaturation and crystallisation modifying properties accomplished by urinary macromolecules and other modifying agents. Received: 14 September 2000 / Revised: 27 December 2000 / Accepted: 27 December 2000     

在尿路结石患者中预测草酸钙结石列线图的建立与应用

目的建立和应用个性化的列线图模型,探讨列线图预测尿路结石患者中草酸钙结石的准确性及可行性。方法回顾性分析2017年1月1日至2018年12月31日在中山大学附属第五医院接受手术治疗的298例泌尿系结石患者资料,以7∶3的比例随机分为建模组和验证组,基于建模组采用最小绝对值收敛和选择算子回归(Lasso)模型及多变量Logistic回归分析选择草酸钙结石的最佳预测特征,根据最佳预测特征以列线图的形式构建预测模型。通过C指数、校准曲线和决策曲线分别评估列线图的辨别力、校准和临床实用性,并基于验证组对外部验证进行评估。结果在LASSO模型中选择的最佳预测特征包括结石位置、甘油三酯(TG)和尿比重(SG)。将以上最佳预测特征和性别、年龄一起建立列线图模型后,建模组和验证组的C指数分别为0.706、 0.603,表明模型具有良好的辨别能力。校准曲线中标准曲线与预测校准曲线贴合良好,提示校正效果良好。决策曲线分析表明,在草酸钙结石可能性阈值为31%时使用该列线图可以在临床上获益。结论本研究建立的列线图预测模型可有效预测草酸钙结石,有助于筛选和早期识别草酸钙尿路结石的高危患者,对泌尿科医师进行临床治...     

An approximate estimate of the ion-activity product of calcium oxalate in rat urine

The objective of this report was to derive a simplified approximate estimate of the ion-activity product of calcium oxalate (AP_CaOx) in rat urine. The relative effect of each urine variable was assessed by means of iterative computerised approximation with the EQUIL2 program. A basic urine composition was chosen from literature and experimental data. The most pronounced influence on AP_CaOx was recorded for urinary calcium, oxalate, citrate, magnesium and volume. Based on these calculations, an AP(CaOx) index_RAT was formulated: . For a 24-h urine sample, factor A takes the value 4067 and factor F should be set to 0.015. Conclusion. A simplified approximate estimate of AP_CaOx was derived for rat urine. There was a reasonably good correspondence between AP(CaOx) index_RAT and AP_CaOx, as derived from EQUIL2 (r=0.890), provided the other urine variables do not deviate very much from that in the basic composition.     

Inhibition of calcium oxalate crystallization in urine

Summary Chromatographic separation of urine showed inhibition of calcium oxalate (CaOx)-crystallization among substances with both large and small molecular weights. Ultrafiltration showed that approximately 80 per cent of the inhibiting activity, as determined in 2 per cent urine, orginated from substances with a molecular weight above 1,000. Dialysed urine was diluted to 7.5 mmol of creatinine per 1 and supersaturated with respect to CaOx. The rate of crystallization in these samples was slower in normal subjects than in stone formers (P< 0.05). The inhibiting activity in diluted urine from the two groups did not differ and neither did the concentration of alcian blue precipitable polyanions. From measurements in diluted urine it was apparent that inhibition was demonstrable with a urine concentration as low as 0.3 per cent.     

Dietary fibre: the effectiveness of a high bran intake in reducing renal calcium excretion

Summary Fifteen healthy women were given a standardized calcium-rich diet (1800 mg calcium/day) with or without 36 g bran for 5 days. A similar study was also carried out with rice, soy and wheat bran. Urine samples were also collected 24 h. With all brans renal calcium excretion decreased and renal oxalic acid excretion increased. However, influence of rice bran was statistically significant. After 5 days of consuming 36 g rice bran/day 14 of 15 subject showed decreased calcium excretion, but increased oxalic acid excretion. Relative supersaturation with calcium oxalate, as a measure for the risk of calcium stone formation, increased after addition of all brans.     

Association of urinary macromolecules with calcium oxalate crystals induced in vitro in normal human and rat urine

This study was undertaken to identify proteins which are found associated with calcium oxalate crystals induced in vitro in normal human and rat urine. Crystallization was initiated by adding sodium oxalate individually to each urine sample without centrifugation and filtration. Crystals were collected and analyzed by scanning electron microscopy and X-ray diffraction. Crystal matrix proteins (CMPs) were obtained by demineralization of the crystals with ethylenediaminetetra-acetic acid (EDTA) and analyzed by western blotting technique for immunological identification. Crystals produced in human urine were found to be a mixture of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) while those produced in rat urine were exclusively COD. CMPs extracted from crystals in human urine comprised, in addition to prothrombin-related proteins, osteopontin and albumin. However, CMPs extracted from crystals in rat urine contained only osteopontin and albumin. Prothrombin-related proteins were found only in trace amounts. In a separate experiment, rat urine samples were supplemented with COM before inducing crystallization. Similar results were observed showing that CMP contained osteopontin, albumin and trace amounts of prothrombin-related proteins. We conclude that several urinary macromolecules including not only prothrombin-related proteins, but also osteopontin and albumin, become associated with CaOx crystals. The incorporation of these proteins in growing stones is not only due to the presence of -carboxyglutamic acid as it was suggested for prothrombin-related proteins, but may be due to other factors such as urinary chemistry, presence of glutamic and aspartic acid residues, and calcium-binding sites.     

前列腺癌患者血清及尿液唾液酸测定的意义

为观察前列腺癌患者血唾液酸（ＳＡ）与病情、疗效及血清ＰＳＡ的关系，按血ＰＳＡ高低将病人分为３组：Ａ组（治疗前，１７例）血ＰＳＡ≥５０μｇ／Ｌ，７０７％为临床Ｃ、Ｄ１、Ｄ２期，病情进展，前列腺症状或骨痛明显。Ｂ组（治疗前，６例）血ＰＳＡ８～３７μｇ／Ｌ，临床分期为Ｃ、Ｄ期，占５０％。Ｃ组（治疗后，８例）血ＰＳＡ＜４μｇ／Ｌ，除临床Ｃ期１例，余均为临床Ｂ期术后，病愈或明显好转。血ＳＡ均值，Ａ组为３０８ｍｍｏｌ／Ｌ，大于Ｂ组２８１ｍｍｏｌ／Ｌ及Ｃ组２１４ｍｍｏｌ／Ｌ；Ａ、Ｃ间有非常显著性差异（Ｐ＜０００１），尿ＳＡ结果同血ＳＡ，Ｐ＜００５。此外，血ＰＳＡ与血ＳＡ（或尿ＳＡ）密切相关，Ｐ＜００１。同为阳性（或阴性）一致率血ＳＡＰＳＡ为８１６％，尿ＳＡＰＳＡ为７２２％。本实验所用“一步法”简便快速，血ＳＡ敏感性１０００％，特异性７８１％，不需进口试剂或设备，有助于前列腺癌的检出与病情疗效追踪观察。     

人工尿液中GAGs对草酸钙结晶凝集的影响

应用人工尿液环境，观察近似人尿ＧＡＧｓ组成的ＧＡＧｓ溶液对草酸结晶凝集的作用，发现有轻度的抑制活性，同时Ｃｈｓ在此环境中对结晶凝集有抑制活性，而ＨＳ却有促进作用。     

Crystallisation of calcium oxalate dihydrate in normal urine in presence of sodium copper chlorophyllin

Summary A method is described for the growth of calcium oxalate dihydrate in normal urine. Soluble chlorophyllin, at a concentration of 20 g/ml inhibited the crystallisation and the growth kinetics of the dihydrate crystals. The inhibitory capacity of chlorophyllin was compared with previous results. Data obtained suggest that the food and drug colourant chlorophyllin might be useful in the treatment of calcium oxalate stone disease.     

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

Summary 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--trypsin inhibitor is responsible has yet to be resolved.     

草酸钙结石患者尿中蛋白结合型γ-羧基谷氨酸的检测意义

目的　探讨含γ 羧基谷氨酸 (Gla)蛋白质及其Gla残基在尿石形成中的作用。　方法　采用过饱和结晶法从新鲜尿液中提取草酸钙晶体基质 ,高效液相色谱法 (HPLC)测定 2 5例草酸钙结石患者尿液和提取的晶体基质中蛋白结合型Gla含量。　结果　草酸钙结石患者尿蛋白结合型Gla浓度为 (1.32± 0 .2 4)nmol/ml,2 4h尿含量为 (2 .0 4± 0 .6 5 ) μmol,显著低于正常人 ;草酸钙结石患者尿液提取的晶体基质中蛋白结合型Gla含量亦显著低于正常人。　结论　草酸钙结石患者尿液中蛋白结合型Gla含量较少 ,尿液含Gla蛋白质的羧基化程度低下可能是结石形成的重要原因之一。