Estimation of the weddellite to whewellite ratio by infrared spectroscopy

Powder samples of 56 calcium oxalate stones the contents of weddellite, whewellite and apatite of which had been determined by thermogravimetry (TG) were studied by infrared spectroscopy (IR). When the ratio of the weddellite content to the total of weddellite and whewellite (weddellite ratio) calculated using Oka's method on the infrared spectra was compared with that determined previously by TG, the correlation coefficient between these ratios was 0.734. For the 24 calcium oxalate stones the apatite content of which was less than 10%, the correlation coefficient between these ratios was 0.976, although the weddellite ratio calculated using Oka's method was significantly higher than that determined by TG (P less than 0.01). In an attempt to estimate the weddellite to whewellite ratio by IR regardless of the content of apatite, the ratio of the depth of the absorption band at 780 cm-1 (H780) to the depth of the absorption band at 1,320 cm-1 (H1320) was compared with the ratio of the whewellite content to the total of whewellite and weddellite contents determined by TG. The correlation coefficient between these ratios was 0.953. We conclude that the ratio of H780 to H1320 determined from the infrared spectra obtained from a 0.3 to 1 mg powder sample of calcium oxalate stone is useful in the estimation of the weddellite to whewellite ratio.     

一水草酸钙与二水草酸钙结石形成机理的研究

目的　探讨一水草酸钙（ＣＯＭ） 与二水草酸钙（ＣＯＤ） 结石形成的机制。　方法　应用红外光谱仪对２５８ 块尿结石成分进行检测,同时检测３０ 例患者２４ｈ 尿液生化指标,对测定结果利用ＳＰＳＳ软件进行ｔ 检验。　结果　（１） 尿钙：ＣＯＭ 组（４．８３ ±１ ．９８）ｍ ｍｏｌ／２４ｈ,ＣＯＤ 组（９．８８ ±４ ．２８）ｍｍｏｌ／２４ｈ,Ｐ＜ ０ ．０１ ;（２） 尿磷：ＣＯＭ 组（１９ ．４０ ±９．６９）ｍ ｍｏｌ／２４ｈ,ＣＯＤ 组（２９．２０ ±１２．００）ｍ ｍｏｌ／２４ｈ,Ｐ＜ ０．０５,两组尿钙、尿磷差异有显著性。　结论　二水草酸钙结石患者尿钙、尿磷高于一水草酸钙结石患者,表明二水草酸钙的形成与高钙尿及磷酸盐异质成核有关,而一水草酸钙的形成可能与尿中抑制物缺乏有关。     

广金钱草黄酮类化合物对草酸钙结石防治机制探讨

草酸钙结石作为尿路结石成分之一,因为其在尿石成份中所占的比例最大及复发率高的原因,成为泌尿系结石研究的重点.目前对于尿石的复发一直未找到好的办法,我国中草药在尿石症的防治上有着潜在的优势.金钱草作为治疗尿石的常用中药之一.被临床医师广泛使用,但其真正有效成份及作用机制却不明确.本文就广金钱草黄酮类化合物对草酸钙结石的防治机制进展作一综述.     

Study of the microstructure of renal stones: Uric acid and calcium oxalate

This paper represents the results of experimental study on the microstructure of uric acid and calcium oxalate crystallites in renal stones. The size distribution parameters and morphological characteristics of the microcrystals forming the stone were determined using SEM and image analysing system. Information on the fabric of the renal stones examined indicates that the mean volume diameter is 15.5 m for uric acid and 32 m for calcium oxalate stones. The polydispersity index , the shape factor , and the distribution of particle shape show close similarity. Quantitative studies on stone microstructure could furnish valuable information on stone genesis.This work was supported by the Kidney Foundation and by the Medical Research Council of Canada.     

Variability of protein content in calcium oxalate monohydrate stones

BACKGROUND AND PURPOSE: Urinary stones are heterogeneous in their fragility to lithotripter shockwaves. As a first step in gaining a better understanding of the role of matrix in stone fragility, we measured extractible protein in calcium oxalate monohydrate (COM) stones that were extensively characterized by micro-computed tomography (micro CT). MATERIALS AND METHODS: Stones were scanned using micro CT (Scanco mCT20, 34 microm). They were ground, and the protein extracted using four methods: 0.25M EDTA, 2% SDS reducing buffer, 9M urea buffer, and 10% acetic acid. Protein was measured using NanoOrange. The SDS extracts were also examined using polyacrylamide electrophoresis (PAGE). RESULTs: Extracted protein was highest with the SDS or urea methods (0.28% +/- 0.13% and 0.24% +/- 0.11%, respectively) and lower using the EDTA method (0.17% +/- 0.05%; P < 0.02). Acetic acid extracted little protein (0.006 +/- 0.002%; P < 0.001). Individual stones were significantly different in extractability of protein by the different methods, and SDS-PAGE revealed different protein patterns for individual stones. Extracted protein did not correlate with X-ray-lucent void percentage, which ranged from 0.06% to 2.8% of stone volume, or with apatite content. CONCLUSIONS: Extractible stone-matrix protein differs for individual COM stones, and yield is dependent on the extraction method. The presence of X-ray-lucent voids or minor amounts of apatite in stones did not correlate with protein content. The amounts of protein recovered were much lower than reported by Boyce, showing that these methods extracted only a fraction of the protein bound up in the stones. The results suggest that none of the methods tested will be useful for helping to answer the question of whether matrix content differs among stones of differing fragility to lithotripter shockwaves.     

Morphology of crystals in calcium oxalate monohydrate kidney stones

Both scanning electron microscopy and atomic force microscopy (AFM) have shown that calcium oxalate monohydrate kidney stones are made up from arrangements of sub micron crystals. The purpose of this investigation was to determine the morphology of these crystals which was obscured by the presence of organic matrix in our earlier study. Sections of stones were treated to remove the protein component of the matrix and then imaged using AFM. Images obtained after proteolysis show that the crystals are in the form of plates stacked on (100) surfaces. These results were confirmed by scanning electron microscopy observations from selected regions of calcium oxalate kidney stone surfaces. The observed crystal sizes are consistent with both the known matrix mass fraction and crystallite growth in the passage through the collecting duct.     

Significance of glycosaminoglycans for the formation of calcium oxalate stones

Glycosaminoglycans (GAG) are polysaccharide chains composed of repeating disaccharides of identical composition. Little is known about the mechanism of their excretion, but there is no doubt that urinary GAGs are degradation products of high molecular weight proteoglycans. Renal excretion takes place chiefly as glomerular filtration, and tubular reabsorption or secretion has not been demonstrated. Differences in the literature comparing GAG excretion in urolithiasis patients and healthy subjects are mainly attributable to methods of analysis and noncomparability of the investigation conditions. We found no differences between the two groups in several series. It is interesting to note that GAG excretion in men is significantly higher than in women, that a circadian rhythm of GAG concentration and excretion occurs in healthy subjects on a standardized diet, and that values are raised postprandially and at night. Seasonal course of GAG excretion curves is almost synchronous for men and women, irrespective of the absolute values, and GAG excretion in the spring and summer significantly exceeds that in winter months by up to 50%. All crystallization models cited demonstrate that GAG reduce the risk of calcium oxalate stone formation. Inhibitors of crystal growth and aggregation act by blocking the growth sites. Inhibition of calcium oxalate crystallization is also attributed to direct binding of calcium to GAG. In the presence of urate ions, and favorable pH, the ability of chondroitin sulfate C to bind calcium may be impaired by as much as 31%. These measurements support the concept that urate ions interact with GAG in urine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Scanning electron microscopic study of calcium oxalate concretions grown in gel system and calcium oxalate stones.

Calcium oxalate concretions grown in gelatin gel medium, and calcium oxalate renal stones were studied by polarized light and scanning electron microscopy. In both cases, the results obtained confirm that the surface crystals have random axial orientation and that the gross configuration seems to be determined by the fibrous organic matrix. In vitro concretions grown in the gelatin gel medium are more resistant to EDTA demineralization and to ultrasonic irradiation than calcium oxalate stones.     

Role of Oxalobacter formigenes in preventing calcium oxalate kidney stones

Objective To screen Oxalobacter formigenes (OxF) from fresh feces of healthy adults, and study its effect on the the prevention of calcium oxalate kidney stones. Methods OxF was screened and cultured from fresh feces of healthy adults. The rat model of calcium oxalate stone was established by esophageal gavage of 0.8% of ethylene glycol. Rats were divided into a control group and four groups of rats with ethylene glycol-induced calcium oxalate kidney stones according to random number table. Three groups were treated with 106 CFU, 107 CFU, 108 CFU viable OxF every day, respectively, for 4 weeks. The blood and 24-hour urine samples were collected to detect the serum creatinine, urea nitrogen, serum and urine calcium, phosphorus, magnesium and urine oxalate every week. At the end of the 4th week, the rats were sacrificed and the kidney tissues were stained with HE and Yasue. The deposition and content of calcium oxalate crystals were observed under a light microscope. Results The bacteria strain isolated from fresh feces of healthy adults was 100% as same as the known ATCC35274 bacteria strain, which means the strain screened is OxF. Among the 5 groups, there were no significant differences in body weight, Scr, BUN, serum calcium, blood magnesium, blood phosphorus, urinary magnesium and urinary phosphorus. The 24-hour urinary calcium excretion in the model group was significantly lower than that of the control group (P＜0.05). After intervention with OxF solution, the 24-hour urinary calcium excretion in the 108 CFU OxF group was significantly higher than that in the model group (P＜0.05), while there was no significant difference between the other intervention groups and the model. The oxalic acid excretion of 106 CFU OxF group and 107 CFU OxF group was lower than that of the model, but the difference did not reach statistical significance (P＞0.05). The 24 h oxalic acid excretion in the 108 CFU OxF group was significantly lower than that of the model at the end of first week (P＜0.05), and continued to decrease for the next 3 weeks. After 4 weeks of intervention, no crystal formation was observed in the control group under the deflection microscope, but a large amount of calcium oxalate crystals were formed in the renal cortex and renal medulla. The crystals were piled up and connected to each other. Yasue staining coincided with the calcium oxalate crystal in the same part of the kidneys. Compared with the model, there was no significant change in the score of calcium oxalate crystal in the kidneys of 106 CFU OxF group and 107 CFU OxF group, while the score of calcium oxalate crystal in the kidneys of 108 CFU OxF group was significantly lower (P＜0.05). Conclusions OxF are successively screened from healthy adults. Daily administration of 108 CFU OxF can safely and effectively reduce the urinary oxalic acid excretion, prevent the formation of calcium oxalate crystals and inhibit the formation of stones in kidneys of rats.     

Developmental morphology of calcium oxalate foreign body stones in rats

Summary Calcium oxalate bladder stones were induced in male rats by implanting plastic foreign bodies and by adding ethylene glycol to their drinking water. The foreign body surface was first coated with cellular debris and some amorphous material. Encrustation with crystals of calcium oxalate started on the third day of implantation. Within 2 weeks the entire surface of a foreign body was covered with crystals and some noncrystalline material. Calcium oxalate monohydrate crystals consisted of platelike crystallites arranged in hemispherulitic or spherulitic habit. Calcium oxalate dihydrate crystals were basically dipyramidal, a majority of them showing interpenetrant twinning. The stone grew by confluent crystal growth and crystal aggregation. A transformation of calcium oxalate monohydrate crystals to calcium oxalate dihydrate also occurred. The matrix consisting of cellular debris and urinary macromolecules was universally distributed in the stone including the inside of crystal bodies.     

Alkali citrate for preventing recurrence of calcium oxalate stones

The use of alkali citrates for preventing the recurrence of calcium oxalate stones was investigated in two trials. In trial I, alkali citrates were given continuously for 18 months to 8 patients who had shown a tendency to recurrent stone formation. In trial II, 12 similar patients were given intermittent therapy for 12 months. The expected changes in urine chemistry were checked at intervals of 3 months. Recurrent stone formation (2 episodes) was observed in only 1 patient (in trial II) during alkali citrate administration; before therapy this patient had suffered an average of 10 attacks of stone formation annually. In the light of the experience gained in these trials, continuous administration of alkali citrates is recommended; the duration of treatment should be tailored to individual needs, but it should not be prolonged indefinitely. Besides having well-attested effectivity of stone prevention, this mode of therapy carries a relatively low incidence of side effects.     

A study of allopurinol in the prevention of recurrent calcium oxalate stones

We studied the effect of allopurinol on the prevention of stone recurrence in 134 patients with recurrent, idiopathic calcium nephrolithiasis. They consisted of 113 male patients and 21 female, between 16 and 72 years with an average age of 42.7. The patients were divided into two groups according to the type of stone occurrence; those with multiple stones without previous stone episodes (multiple stone group), and the those with recurrent stones (stone episode group). Twenty three patients belonged to the multiple stone group and 111 patients belonged to the stone episode group. The stones in 19 of the 23 patients in the multiple stone group remained stable throughout the study, while stones in 4 grew. Fifty-nine of the 111 patients in the stone episode group were free from recurrence, but the others showed recurrence. Statistical analyses was done on the stone episode group. The stone recurrence rate of all of the 111 cases showed significant decrease during prophylactic treatment with allopurinol (p less than 0.01), although the observation period before treatment was 73.0 +/- 65.8 months and that during and after treatment was 28.2 +/- 12.1 months. During the two years before and after prophylaxis 79 patients also showed a significantly decreased recurrence rate. Moreover, regarding 37 cases without any stones at the start of treatment, stone recurrence rate decreased significantly after the administration of allopurinol. Throughout this study, we used a new method for evaluating reasonable stone recurrence. It did not calculate the number of stones recurred, but the stone-forming circumstance in each kidney.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estimation by infrared spectrophotometer of the calcium oxalate dihydrate to calcium oxalate monohydrate ratio

According to the theoretical expression for calibration curve as a function of the optical absorption ratio of two peaks and with the analysis of the infrared spectra of the mixture samples of commercial calcium oxalate monohydrate and synthesized calcium oxalate dihydrate, the following quadratic equation was obtained; Y = 1.79 X2 - 30.90 X + 107.04 in which Y is the percentage of the purity of calcium oxalate dihydrate and X is the ratio of the relative optical absorption at 660 cm.-1 (the wave number at a characteristic absorption peak of calcium oxalate monohydrate) to that at 610 cm.-1 (that of calcium oxalate dihydrate) by regarding the line as a base-line that links the absorption valley at around 700 cm.-1 with that at 550 cm.-1 The linear correlation coefficient of the actual purity to the estimated purity obtained from this formula of calcium oxalate dihydrate is 0.995. When this formula is applied to the results derived from the infrared spectra of the mixture samples of commercial calcium oxalate monohydrate and calcium oxalate dihydrate obtained from urinary stones in duplicate in each percentage, the linear correlation coefficient is 0.991. This estimation method by infrared spectrophotometer of the calcium oxalate dihydrate to calcium oxalate monohydrate ratio gave a very close correlation between actual and estimated purity of calcium oxalate dihydrate and seems useful in the study of calcium oxalate urolithiasis.     

Metabolic characteristics of the elderly with recurrent calcium oxalate stones.

OBJECTIVE: To determine the metabolic characteristics of elderly patients with recurrent calcium oxalate stones. PATIENTS AND METHODS: Metabolic abnormalities were investigated in 88 patients with recurrent calcium oxalate stones, including 70 aged <60 years and 18 aged >/=60 years. The frequency of each metabolic abnormality and the value of each urinary constituent were compared among subgroups of age and gender. RESULTS: Hyperoxaluria was the most common abnormality, present in 56% and 67% of patients aged <60 and >/=60 years, respectively. Hyperuricosuria was significantly more common in older than in younger patients. There were no significant differences in the frequencies of hypercalciuria and hypocitraturia between the age groups. The urinary excretion of oxalate and the ratio of oxalate to creatinine were significantly greater in older than in younger men. The frequency of low urine volume was lower in older than in younger patients and the mean urinary volume was also greater in the older group. CONCLUSIONS: Hyperuricosuria and hyperoxaluria seem to be essential risk factors for calcium oxalate stone formation in elderly patients. Urinary oxalate excretion is significantly greater in older than in younger stone formers and is more prominent in men.     

Oxalobacter formigenes may reduce the risk of calcium oxalate kidney stones

Most kidney stones are composed primarily of calcium oxalate. Oxalobacter formigenes is a Gram-negative, anaerobic bacterium that metabolizes oxalate in the intestinal tract and is present in a large proportion of the normal adult population. It was hypothesized that the absence of O. formigenes could lead to increased colonic absorption of oxalate, and the subsequent increase in urinary oxalate could favor the development of stones. To test this hypothesis, a case-control study involving 247 adult patients with recurrent calcium oxalate stones and 259 age-, gender-, and region-matched control subjects was performed. The prevalence of O. formigenes, determined by stool culture, was 17% among case patients and 38% among control subjects; on the basis of multivariate analysis controlling demographic factors, dietary oxalate, and antibiotic use, the odds ratio for colonization was 0.3 (95% confidence interval 0.2 to 0.5). The inverse association was consistently present within strata of age, gender, race/ethnicity, region, and antibiotic use. Among the subset of participants who completed a 24-h urine collection, the risk for kidney stones was directly proportional to urinary oxalate, but when urinary factors were included in the multivariable model, the odds ratio for O. formigenes remained 0.3 (95% confidence interval 0.1 to 0.7). Surprisingly, median urinary oxalate excretion did not differ with the presence or absence of O. formigenes colonization. In conclusion, these results suggest that colonization with O. formigenes is associated with a 70% reduction in the risk for being a recurrent calcium oxalate stone former.     

Prophylaxis of calcium oxalate stones by Herniaria hirsuta on experimentally induced nephrolithiasis in rats

OBJECTIVE: To evaluate the prophylactic potential of a herbal decoction from Herniaria hirsuta, a medicinal plant widely used in Morocco to treat kidney stones, by assessing the effect of oral administration in experimentally induced calcium oxalate (CaOx) nephrolithiasis in rats. MATERIAL AND METHODS: Two groups of six rats each were rendered nephrolithic by treating with ethylene glycol 0.75% and ammonium chloride 1% for 3 days, and then ethylene glycol only for 3 weeks. Maintained on ethylene glycol, one group of rats was also given 1 mL/day of the plant decoction, while the others received 1 mL of water instead for 2 weeks. Urine samples (24 h) were collected individually at 1, 3, 7, and 14 days for physicochemical analysis. On completing the treatment the kidneys were collected and analysed by light microscopy. RESULTS: The water intake and diuresis decreased in the treated rats; there was no significant difference in urinary pH between the groups. Urinary chemistry was apparently unaffected by the plant extract, except for the magnesium content, which was higher in treated rats. Crystalluria was characterized by the excretion of large CaOx monohydrate and dihydrate crystals in untreated, but smaller crystals in treated rats. The histology showed large deposits of CaOx crystals in all parts of the kidney in untreated rats but with almost no deposits in those of treated rats. CONCLUSION: H. hirsuta has an impressive prophylactic effect on CaOx stones in nephrolithic rats; the effect did not seem to be mediated by biochemical or diuretic changes.     

Enlargement of calcium oxalate stones to clinically significant size in an in-vitro stone generator

OBJECTIVE: To develop and validate an in vitro method suitable for the quantitative investigation of the growth of calcium oxalate stones through to a clinically significant size. MATERIALS AND METHODS: Small fragments of calcium oxalate calculi were suspended in a mixed suspension/mixed product removal crystalliser supplied with artificial urine supersaturated with calcium oxalate. The fragments were weighed at regular intervals until they reached approximately equal 500 mg. The results were plotted as weight against time and fitted to equations corresponding to constant increase in diameter, surface area-controlled and constant-deposition growth patterns. The choice of the most appropriate model was based on the squared regression coefficient (r2). RESULTS: Eight fragments (2-6 mm in diameter) were grown to approximately 10 mm in diameter over periods from 137 to 369 h. Seven of the growth curves were best-fitted (r2 > or = 0.988) by the equation w = kt(3/2) + c, where w is the weight, k is a growth constant, t is the time and c is a constant approximating to the initial weight. This corresponds to a surface area-dependent mechanism. CONCLUSIONS: The growth of these small fragments to a clinically significant size accelerated throughout the experimental period in a way which was consistent with a surface area-dependent mechanism. We have developed a resilient model suitable for studying the kinetics of calcium oxalate stone growth in vitro.