struvite and calcium-phosphate--dibasic--dihydrate

Kidney stone disease is one of the oldest diseases known to medicine; however, the mechanisms of stone formation and development remain largely unclear. Over the past decades, a variety of theories and strategies have been developed and utilized in the surgical management of kidney stones, as a result of recent technological advances. Observations from the authors and other research groups suggest that there are five entirely different main mechanisms for kidney stone formation. Urinary supersaturation and crystallization are the driving force for intrarenal crystal precipitation. Randall's plaques are recognized as the origin of calcium oxalate stone formation. Sex hormones may be key players in the development of nephrolithiasis and may thus be potential targets for new drugs to suppress kidney stone formation. The microbiome, including urease‑producing bacteria, nanobacteria and intestinal microbiota, is likely to have a profound effect on urological health, both positive and negative, owing to its metabolic output and other contributions. Lastly, the immune response, and particularly macrophage differentiation, play crucial roles in renal calcium oxalate crystal formation. In the present study, the current knowledge for each of these five aspects of kidney stone formation is reviewed. This knowledge may be used to explore novel research opportunities and improve the understanding of the initiation and development of kidney stones for urologists, nephrologists and primary care.

Topics: Apatites; Calcinosis; Calcium Oxalate; Calcium Phosphates; Gastrointestinal Microbiome; Humans; Kidney; Kidney Calculi; Struvite; Uric Acid; Urolithiasis

Renal lithiasis is a multifactorial disease. An important number of etiologic factors can be adequately modified through diet, since it must be considered that the urine composition is directly related to diet. In fact, the change of inappropriate habitual diet patterns should be the main measure to prevent kidney stones. In this paper, the relation between different dietary factors (liquid intake, pH, calcium, phosphate, oxalate, citrate, phytate, urate and vitamins) and each type of renal stone (calcium oxalate monohydrate papillary, calcium oxalate monohydrate unattached, calcium oxalate dihydrate, calcium oxalate dihydrate/hydroxyapatite, hydroxyapatite, struvite infectious, brushite, uric acid, calcium oxalate/uric acid and cystine) is discussed.

Topics: Calcium Oxalate; Calcium Phosphates; Cystine; Diet; Diet, Vegetarian; Dietary Proteins; Drinking; Durapatite; Humans; Hydrogen-Ion Concentration; Kidney Calculi; Magnesium Compounds; Nutritional Physiological Phenomena; Phosphates; Sodium Chloride, Dietary; Struvite; Uric Acid

Topics: Apatites; Calcification, Physiologic; Calcium Phosphates; Crystallography; Magnesium Compounds; Molecular Structure; Phosphates; Structure-Activity Relationship; Struvite

Topics: Apatites; Calcium Compounds; Calcium Oxalate; Calcium Phosphates; History, 18th Century; History, 19th Century; History, 20th Century; Humans; Magnesium Compounds; Minerals; Names; Phosphates; Struvite; Urinary Calculi

The most important phosphates involved in urinary stone disease are carbonate apatite, brushite, and struvite. Overall, phosphate stones account for 12-20% of all stones, with a downward trend for struvite and an increase in carbonate apatite being observed in the last decade. The physicochemical basis for the formation of phosphate calculi is supersaturation. Once the solubility product has been exceeded, a metastable process of supersaturation begins, with slow crystalline growth. If a critical limit of supersaturation is exceeded, large-scale spontaneous precipitation of crystals occurs in a second stage. No urinary tract infection is involved in brushite stone formation. Although infection is not a prerequisite for the formation of carbonate apatite stones, infective conditions favor carbonate apatite formation. Struvite is the characteristic infection calculus, formed as a result of urinary tract infection with urease-producing bacteria. During the first episode of urinary stone disease a definitive diagnosis of the type of stone involved is very difficult without analysis of the latter by infrared spectroscopy or X-ray diffraction. In recurrent disease, appropriate treatment can be initiated on the basis of the previous stone analysis in the majority of cases. The best means of preventing recurrent disease involving any type of phosphate stone is definitive calculus removal by shock-wave lithotripsy, percutaneous stone removal, or open surgery (especially in children). Chemolysis via acidification of the urine with Suby G solution or hemicidrin supported by oral acidification, achieved by the metabolism of L-methionine, and antibiotic therapy (especially for infectious stones) are important adjuvant modalities of therapy. After therapy of phosphate stones, metaphylaxis involving controlled urinary acidification with L-methionine supports the treatment of infection and, at a pH value of less than 6.2 and urine dilution to 2.5 l/24 h, prevents the crystallization of struvite, brushite, and carbonate apatite.

Topics: Acids; Apatites; Calcium Phosphates; Crystallization; Humans; Magnesium Compounds; Phosphates; Struvite; Urinary Calculi

The treatment of small renal pelvic and ureteric calculi can be performed with relative safety and efficacy using lithotripsy or an endourological method. There remains however, a proportion of stones that are resistant to these methods because of their anatomical position, physical composition or sheer size. To these stones must be applied a treatment strategy using the variety of techniques to their maximum advantage. This article aims to review the accumulated experience on the management of these more complex urinary calculi.

Topics: Calcium Phosphates; Combined Modality Therapy; Cystine; Humans; Kidney; Kidney Calculi; Lithotripsy; Magnesium; Magnesium Compounds; Nephrostomy, Percutaneous; Phosphates; Struvite

To assess the potential of automated machine-learning methods for recognizing urinary stones in endoscopy.. Surface and section images of 123 urinary calculi (109 ex vivo and 14 in vivo stones) were acquired using ureteroscopes. The stones were more than 85% 'pure'. Six classes of urolithiasis were represented: Groups I (calcium oxalate monohydrate, whewellite), II (calcium oxalate dihydrate, weddellite), III (uric acid), IV (brushite and struvite stones), and V (cystine). The automated stone recognition methods that were developed for this study followed two types of approach: shallow classification methods and deep-learning-based methods. Their sensitivity, specificity and positive predictive value (PPV) were evaluated by simultaneously using stone surface and section images to classify them into one of the main morphological groups (subgroups were not considered in this study).. Using shallow methods (based on texture and colour criteria), relatively high sensitivity, specificity and PPV for the six classes were attained: 91%, 90% and 89%, respectively, for whewellite; 99%, 98% and 99% for weddellite; 88%, 89% and 88% for uric acid; 91%, 89% and 90% for struvite; 99%, 99% and 99% for cystine; and 94%, 98% and 99% for brushite. Using deep-learning methods, the sensitivity, specificity and PPV for each of the classes were as follows: 99%, 98% and 97% for whewellite; 98%, 98% and 98% for weddellite; 97%, 98% and 98% for uric acid; 97%, 97% and 96% for struvite; 99%, 99% and 99% for cystine; and 94%, 97% and 98% for brushite.. Endoscopic stone recognition is challenging, and few urologists have sufficient expertise to achieve a diagnosis performance comparable to morpho-constitutional analysis. This work is a proof of concept that artificial intelligence could be a solution, with promising results achieved for pure stones. Further studies on a larger panel of stones (pure and mixed) are needed to further develop these methods.

Topics: Artificial Intelligence; Cystine; Humans; Struvite; Uric Acid; Urinary Calculi

In lithogenesis, for a stone to form it is necessary that the urine is supersaturated with respect to the salt that will constitute the future stone. The objective was to analyze the urinary saturations of Calcium Oxalate (CaOxa), brushite (calcium phosphate), struvite (ammonium-magnesium phosphate) and uric acid (UA) in children with and without lithiasis. Correlate them with the different parameters involved in the lithiasic process. And compare saturations in children with or without overweight.. We examined 108 healthy children and 53 patients diagnosed with lithiasis. In 24-h urine, the different biochemical parameters involved in lithiasis and the saturation levels of CaOxa, brushite, struvite and UA.. We studied 108 healthy children with a mean age of 9.5 ± 3.9 years. Renal lithiasis was diagnosed in 53 patients with an average age of 10.5 ± 5.8 years. Children with lithiasis had higher saturation values of CaOxa (4.86 ± 2.71 vs. 3.15 ± 1.99,. The mean values of calcium oxalate and brushite saturations were higher in children with lithiasis. Uric acid saturation was elevated in overweight children. Finally, urinary pH greatly influenced uric acid saturation.

Topics: Adolescent; Ammonium Compounds; Calcium Oxalate; Calcium Phosphates; Child; Child, Preschool; Humans; Kidney Calculi; Overweight; Struvite; Uric Acid; Urinary Calculi

Human kidney stones form. Stone fragments were collected from a randomly chosen cohort of 20 patients using standard percutaneous nephrolithotomy (PCNL). Fourier transform infrared (FTIR) spectroscopy indicated that 18 of these patients were calcium oxalate (CaOx) stone formers, whereas one patient formed each formed brushite and struvite stones. This apportionment is consistent with global stone mineralogy distributions. Stone fragments from seven of these 20 patients (five CaOx, one brushite, and one struvite) were thin sectioned and analyzed using brightfield (BF), polarization (POL), confocal, super-resolution autofluorescence (SRAF), and Raman techniques. DNA from remaining fragments, grouped according to each of the 20 patients, were analyzed with amplicon sequencing of 16S rRNA gene sequences (V1-V3, V3-V5) and internal transcribed spacer (ITS1, ITS2) regions.. Bulk-entombed DNA was sequenced from stone fragments in 11 of the 18 patients who formed CaOx stones, and the patients who formed brushite and struvite stones. These analyses confirmed the presence of an entombed low-diversity community of bacteria and fungi, including

Topics: Bacteria; Calcium Oxalate; Calcium Phosphates; Fungi; Humans; Kidney Calculi; RNA, Ribosomal, 16S; Struvite

To assess the recall of a deep learning (DL) method to automatically detect kidney stones composition from digital photographs of stones.. A total of 63 human kidney stones of varied compositions were obtained from a stone laboratory including calcium oxalate monohydrate (COM), uric acid (UA), magnesium ammonium phosphate hexahydrate (MAPH/struvite), calcium hydrogen phosphate dihydrate (CHPD/brushite), and cystine stones. At least two images of the stones, both surface and inner core, were captured on a digital camera for all stones. A deep convolutional neural network (CNN), ResNet-101 (ResNet, Microsoft), was applied as a multi-class classification model, to each image. This model was assessed using leave-one-out cross-validation with the primary outcome being network prediction recall.. The composition prediction recall for each composition was as follows: UA 94% (n = 17), COM 90% (n = 21), MAPH/struvite 86% (n = 7), cystine 75% (n = 4), CHPD/brushite 71% (n = 14). The overall weighted recall of the CNNs composition analysis was 85% for the entire cohort. Specificity and precision for each stone type were as follows: UA (97.83%, 94.12%), COM (97.62%, 95%), struvite (91.84%, 71.43%), cystine (98.31%, 75%), and brushite (96.43%, 75%).. Deep CNNs can be used to identify kidney stone composition from digital photographs with good recall. Future work is needed to see if DL can be used for detecting stone composition during digital endoscopy. This technology may enable integrated endoscopic and laser systems that automatically provide laser settings based on stone composition recognition with the goal to improve surgical efficiency.

Topics: Algorithms; Calcium Oxalate; Calcium Phosphates; Cystine; Deep Learning; Humans; Image Interpretation, Computer-Assisted; Kidney Calculi; Photography; ROC Curve; Struvite; Uric Acid

Previous studies have shown that split-bolus protocols in virtual non-contrast (VNC) reconstructions of dual-energy computed tomography (DE-CT) significantly decrease radiation dose in patients with urinary stone disease. To evaluate the impact on kidney stone detection rate of stone composition, size, tube voltage, and iodine concentration for VNC reconstructions of DE-CT.. In this prospective study, 16 kidney stones of different sizes (1.2-4.5 mm) and compositions (struvite, cystine, whewellite, brushite) were placed within a kidney phantom. Seventy-two scans with nine different iodine contrast agents/saline solutions with increasing attenuation (0-1400 HU) and different kilovoltage settings (70 kV/150 kV; 80 kV/150 kV; 90 kV/150 kV; 100 kV/150 kV) were performed. Two experienced radiologists independently rated the images for the presence and absence of stones. Multivariate classification tree analysis and descriptive statistics were used to evaluate the diagnostic performance.. Classification tree analysis revealed a higher detection rate of renal calculi > 2 mm in size compared with that of renal calculi < 2 mm (84.7%; 12.7%; p < 0.001). For stones with a diameter > 2 mm, the best results were found at 70 kV/Sn 150 kV and 80 kV/Sn 150 kV in scans with contrast media attenuation of 600 HU or less, with sensitivity of 99.6% and 96.0%, respectively. A higher luminal attenuation (> 600 HU) resulted in a significantly decreased detection rate (91.8%, 0-600 HU; 70.7%, 900-1400 HU; p < 0.001). In our study setup, the detection rates were best for cystine stones.. Scan protocols in DE-CT with lower tube current and lower contrast medium attenuation show excellent results in VNC for stones larger than 2 mm but have limitations for small stones.. • The detection rate of virtual non-contrast reconstructions is highly dependent on the surrounding contrast medium attenuation at the renal pelvis and should be kept as low as possible, as at an attenuation higher than 600 HU the VNC reconstructions are susceptible to masking ureteral stones. • Protocols with lower tube voltages (70 kV/Sn 150 kV and 80 kV/Sn 150 kV) improve the detection rate of kidney stones in VNC reconstructions. • The visibility of renal stones in virtual non-contrast of dual-energy CT is highly associated with the size, and results in a significantly lower detection rate in stones below 2 mm.

Topics: Calcium Oxalate; Calcium Phosphates; Contrast Media; Cystine; Humans; Image Processing, Computer-Assisted; Iodine; Kidney Calculi; Phantoms, Imaging; Prospective Studies; Radiation Dosage; Struvite; Tomography, X-Ray Computed; Urinary Calculi

Calcium phosphate (CaP)-containing materials, such as hydroxyapatite and brushite, are well studied bone grafting materials owing to their similar chemical compositions to the mineral phase of natural bone and kidney calculi. In recent studies, magnesium phosphate (MgP)-containing compounds, such as newberyite and struvite, have shown promise as alternatives to CaP. However, the different ways in degradation and release of Mg

Topics: Animals; Biocompatible Materials; Bone Cements; Calcium Phosphates; Cells, Cultured; Chemical Precipitation; Compressive Strength; Magnesium Compounds; Magnesium Oxide; Materials Testing; Mice; Microtechnology; Molecular Conformation; Osteoblasts; Phosphates; Polymerization; Porosity; Powders; Struvite; Tissue Engineering; Tissue Scaffolds

To explore underlying mechanism of urinary stones formation, the composition and microstructure of urinary stones were analyzed systematically with a large sample study from China.. A total of 2437 urinary stones were obtained from the urology department at our Hospital. The composition of the stones was analyzed by Fourier transform infrared spectroscopy (FTIR). Meanwhile, the microstructure and element distribution were observed with scanning electron microscopy combined with element distribution analysis (SEM-EDAX).. Urinary stones were classified into eight types, that were consisted of calcium oxalate stones (1301/2437, 53.39%), calcium phosphate stones (131/2437, 5.38%), anhydrous uric acid stones (434/2437, 17.81%), magnesium ammonium phosphate stones (12/2437, 0.49%), sodium urate stones (5/2437, 0.21%), brushite stones (4/2437, 0.16%), cystine stones (3/2437, 0.12%) and mixed stones (547/2437, 22.45%, ten subtypes were included). Under SEM, they displayed distinct microstructures: plank-like, brick-like, polyhedron or paliform crystals for calcium oxalate stones, similar sized echin-sphere or rough bulbiform or tree bark-like crystals for calcium phosphate stones, rotten-wood-like or petrous crystals for anhydrous uric acid stones, globular or gallet-like crystals for magnesium ammonium phosphate stones, sawdust-like crystals for sodium urate stones, broken-wood-like crystals for brushite stones, stacking hexagonal cystine crystals for cystine stones, and two or more of the above crystals for mixed stones. Meanwhile, they also presented distinct elemental composition and distribution by EDAX.. Urinary stones can be classified into eight types, and exhibit a diversity of microstructure and elemental compositions in China. The formation process of different types of urinary stones may be diverse.

Topics: Calcium Oxalate; Calcium Phosphates; China; Cystine; Humans; Microscopy, Electron, Scanning; Spectroscopy, Fourier Transform Infrared; Struvite; Uric Acid; Urinary Calculi

OBJECTIVE To determine whether dual-energy CT (DECT) could accurately differentiate the composition of common canine uroliths in a phantom model. SAMPLE 30 canine uroliths with pure compositions. PROCEDURES Each urolith was composed of ≥ 70% struvite (n = 10), urate (8), cystine (5), calcium oxalate (4), or brushite (3) as determined by standard laboratory methods performed at the Canadian Veterinary Urolith Centre. Uroliths were suspended in an agar phantom, and DECT was performed at low (80 kV) and high (140 kV) energies. The ability of low- and high-energy CT numbers, DECT number, and DECT ratio to distinguish uroliths on the basis of composition was assessed with multivariate ANOVA. RESULTS No single DECT measure differentiated all urolith types. The DECT ratio differentiated urate uroliths from all other types of uroliths. The DECT and low-energy CT numbers were able to differentiate between 8 and 7 pairs of urolith types, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that DECT was unable to differentiate common types of canine uroliths in an in vitro model; therefore, it is unlikely to be clinically useful for determining urolith composition in vivo. Given that the primary reasons for determining urolith composition in vivo are to predict response to shock wave lithotripsy and develop a treatment plan, future research should focus on the correlation between DECT measurements and urolith fragility rather than urolith composition.

Topics: Animals; Calcium Oxalate; Calcium Phosphates; Canada; Dog Diseases; Dogs; Struvite; Tomography, X-Ray Computed; Uric Acid; Urinary Calculi

We present in this paper accurate and reliable Raman and IR spectral identification of mineral constituents in nine samples of renal calculi (kidney stones) removed from patients suffering from nephrolithiasis. The identified mineral components include Calcium Oxalate Monohydrate (COM, whewellite), Calcium Oxalate Dihydrate (COD, weddellite), Magnesium Ammonium Phosphate Hexahydrate (MAPH, struvite), Calcium Hydrogen Phosphate Dihydrate (CHPD, brushite), Pentacalcium Hydroxy Triphosphate (PCHT, hydroxyapatite) and Uric Acid (UA). The identification is based on a satisfactory assignment of all the observed IR and Raman bands (3500-400c m(-1)) to chemical functional groups of mineral components in the samples, aided by spectral analysis of pure materials of COM, MAPH, CHPD and UA. It is found that the eight samples are composed of COM as the common component, the other mineral species as common components are: MAPH in five samples, PCHT in three samples, COD in three samples, UA in three samples and CHPD in two samples. One sample is wholly composed of UA as a single component; this inference is supported by the good agreement between ab initio density functional theoretical spectra and experimental spectral measurements of both sample and pure material. A combined application of Raman and IR techniques has shown that, where the IR is ambiguous, the Raman analysis can differentiate COD from COM and PCHT from MAPH.

Topics: Calcium Oxalate; Calcium Phosphates; Durapatite; Humans; Kidney Calculi; Magnesium Compounds; Phosphates; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Struvite; Uric Acid

Kidney stones are heterogeneous but often grouped together. The potential effects of patient demographics and calendar month (season) on stone composition are not widely appreciated.. The first stone submitted by patients for analysis to the Mayo Clinic Metals Laboratory during 2010 was studied (n=43,545). Stones were classified in the following order: any struvite, any cystine, any uric acid, any brushite, majority (≥50%) calcium oxalate, or majority (≥50%) hydroxyapatite.. Calcium oxalate (67%) was the most common followed by hydroxyapatite (16%), uric acid (8%), struvite (3%), brushite (0.9%), and cystine (0.35%). Men accounted for more stone submissions (58%) than women. However, women submitted more stones than men between the ages of 10-19 (63%) and 20-29 (62%) years. Women submitted the majority of hydroxyapatite (65%) and struvite (65%) stones, whereas men submitted the majority of calcium oxalate (64%) and uric acid (72%) stones (P<0.001). Although calcium oxalate stones were the most common type of stone overall, hydroxyapatite stones were the second most common before age 55 years, whereas uric acid stones were the second most common after age 55 years. More calcium oxalate and uric acid stones were submitted in the summer months (July and August; P<0.001), whereas the season did not influence other stone types.. It is well known that calcium oxalate stones are the most common stone type. However, age and sex have a marked influence on the type of stone formed. The higher number of stones submitted by women compared with men between the ages of 10 and 29 years old and the change in composition among the elderly favoring uric acid have not been widely appreciated. These data also suggest increases in stone risk during the summer, although this is restricted to calcium oxalate and uric acid stones.

Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Calcium Oxalate; Calcium Phosphates; Child; Child, Preschool; Cystine; Durapatite; Female; Humans; Infant; Infant, Newborn; Kidney Calculi; Magnesium Compounds; Male; Middle Aged; Phosphates; Seasons; Sex Factors; Struvite; United States; Uric Acid; Young Adult

Results of the structural analysis of urinary sediments by means of infrared spectral microscopy are presented. The results are in good agreement with the results of standard optical microscopy in the case of single-component and crystalline urinary sediments. It is found that for noncrystalline or multicomponent sediments, the suggested spectroscopic method is superior to optical microscopy. The chemical structure of sediments of any molecular origin can be elucidated by this spectroscopic method. The method is sensitive enough to identify solid particles of drugs present in urine. Sulfamethoxazole and traces of other medicines are revealed in this study among the other sediments. We also show that a rather good correlation exists between the type of urinary sediments and the renal stones removed from the same patient. Spectroscopic studies of urinary stones and corresponding sediments from 76 patients suffering from renal stone disease reveal that in 73% of cases such correlation exists. This finding is a strong argument for the use of infrared spectral microscopy to prevent kidney stone disease because stones can be found in an early stage of formation by using the nonintrusive spectroscopic investigation of urinary sediments. Some medical recommendations concerning the overdosing of certain pharmaceuticals can also be derived from the spectroscopic studies of urinary sediments.

Topics: Calcium Oxalate; Calcium Phosphates; Durapatite; Humans; Kidney Calculi; Magnesium Compounds; Microscopy; Optical Phenomena; Phosphates; Spectroscopy, Fourier Transform Infrared; Struvite; Uric Acid; Urinary Calculi

To evaluate the compositions of the kidney stones obtained from different regions of Turkey and to present the gender and regional differences.. The study included 6453 kidney stones obtained from patients from different parts of Turkey. All of the stones were obtained using ureterorenoscopy, percutaneous stone surgery, laparoscopic or open stone surgery, or extracorporeal shock wave lithotripsy. X-ray diffraction crystallography method was used for analysis.. At the end of the analysis, 11 different stone types including calcium oxalate (Ca-ox) monohydrate (whewellite, COM), Ca-ox dihydrate (weddellite, COD), uric acid, cystine, struvite, biurea, xanthine brushite, quartz, whitlockite, and dahlite were determined either in pure or mixed conditions. Of the stones, 80.4% were Ca-ox (55.7% COM, 5.9% COD, 18.8% COM + COD), 4.8% uric acid, 3.1% cystine, and 3.3% were phosphate stones (dahlite, brushite, struvite, whitlockite). The remaining 8.4% of the stones were in mixed form with different combinations. Of the patients, 4411 were men (68.3%) and 2042 were women (31.7%).. Ca-ox was the most frequently encountered stone type in our country as it is worldwide. The distribution of the other stone types is different than the other countries. The information about the structure of the stone has significant contribution to the understanding of the stone formation etiology, programming of the treatment process, and prevention of the recurrences. The study is significant in presenting the stone profile of Turkey.

Topics: Apatites; Biureas; Calcium Oxalate; Calcium Phosphates; Crystallography, X-Ray; Cystine; Female; Humans; Kidney Calculi; Magnesium Compounds; Male; Phosphates; Quartz; Sex Factors; Struvite; Turkey; Uric Acid; Xanthine

Bone loss due to accidents or tissue diseases requires replacement of the structure by either autografts, allografts, or artificial materials. Reactive cements, which are based on calcium phosphate chemistry, are commonly used in nonload bearing areas such as the craniofacial region. Some of these materials are resorbed by the host under physiological conditions and replaced by bone. The aim of this study was to test different calcium and magnesium cement composites in vitro for their use as bone substitution material. Phase composition of calcium deficient hydroxyapatite (Ca(9) (PO(4) )(5) HPO(4) OH), brushite (CaHPO(4) ·2H(2) O), and struvite (MgNH(4) PO(4) ·6H(2) O) specimens has been determined by means of X-ray diffraction, and compressive strength was measured. Cell growth and activity of osteoblastic cells (MG 63) on the different surfaces was determined, and the expression of bone marker proteins was analyzed by western blotting. Cell activity normalized to cell number revealed higher activity of the osteoblasts on brushite and struvite when compared to hydroxyapatite and also the expression of osteoblastic marker proteins was highest on brushite scaffolds. While brushite sets under acidic conditions, formation of struvite occurs under physiological pH, similar to hydroxyapatite cements, providing the possibility of additional modifications with proteins or other active components.

Topics: Animals; Bone Cements; Bone Substitutes; Calcium Phosphates; Cell Proliferation; Durapatite; Humans; Magnesium Compounds; Osteoblasts; Phosphates; Protein Biosynthesis; Struvite

The purpose of this study was to determine the ex vivo ability of dual-energy dual-source CT (DSCT) with additional tin filtration to differentiate among five groups of human renal stone types.. Forty-three renal stones of 10 types were categorized into five primary groups on the basis of effective atomic numbers, which were calculated as the weighted average of the atomic numbers of constituent atoms. Stones were embedded in porcine kidneys and placed in a 35-cm water phantom. Dual-energy DSCT scans were performed at 80 and 140 kV with and without tin filtration of the 140-kV beam. The CT number ratio, defined as the ratio of the CT number of a given material in the low-energy image to the CT number of the same material in the high-energy image, was calculated on a volumetric voxel-by-voxel basis for each stone. Statistical analysis was performed, and receiver operating characteristic (ROC) curves were plotted to compare the difference in CT number ratio with and without tin filtration, and to measure the discrimination among stone groups.. The CT number ratio of non-uric acid stones increased on average by 0.17 (range, 0.03-0.36) with tin filtration. The CT number ratios for non-uric acid stone groups were not significantly different (p > 0.05) between any of the two adjacent groups without tin filtration. Use of the additional tin filtration on the high-energy x-ray tube significantly improved the separation of non-uric acid stone types by CT number ratio (p < 0.05). The area under the ROC curve increased from 0.78 to 0.84 without fin filtration and to 0.89-0.95 with tin filtration.. Our results showed better separation among different stone types when additional tin filtration was used on dual-energy DSCT. The increased spectral separation allowed a five-group stone classification scheme. Some overlapping between particular stone types still exists, including brushite and calcium oxalate.

Topics: Animals; Apatites; Calcium Oxalate; Calcium Phosphates; Cystine; Diagnosis, Differential; Durapatite; Humans; In Vitro Techniques; Kidney Calculi; Magnesium Compounds; Phantoms, Imaging; Phosphates; Radiographic Image Interpretation, Computer-Assisted; Retrospective Studies; ROC Curve; Sensitivity and Specificity; Struvite; Swine; Tomography, X-Ray Computed; Uric Acid

Bone replacement using synthetic and degradable materials is desirable in various clinical conditions. Most applied commercial materials are based on hydroxyapatite, which is not chemically degradable under physiological conditions. Here we report the effect of a long-term intramuscular implantation regime on the dissolution of various low temperature calcium and magnesium phosphate ceramics in vivo. The specimens were analysed by consecutive radiographs, micro-computed tomography scans, compressive strength testing, scanning electron microscopy and X-ray diffractometry. After 15months in vivo, the investigated materials brushite (CaHPO(4)·2H(2)O), newberyite (MgHPO(4)·3H(2)O), struvite (MgNH(4)PO(4)·6H(2)O) and hydroxyapatite (Ca(9)(PO(4))(5)HPO(4)OH) showed significant differences regarding changes of their characteristics. Struvite presented the highest loss of mechanical performance (95%), followed by newberyite (67%) and brushite (41%). This was accompanied by both a distinct extent of cement dissolution as well as changes of the phase composition of the retrieved cement implants. While the secondary phosphate phases (brushite, newberyite, struvite) completely dissolved, re-precipitates of whitlockite and octacalcium phosphate were formed in either particulate or whisker-like morphology. Furthermore, for the first time the possibility of a macropore-free volume degradation mechanism of bioceramics was demonstrated.

Topics: Bone Cements; Calcium Phosphates; Ceramics; Cold Temperature; Durapatite; Magnesium Compounds; Microscopy, Electron, Scanning; Phosphates; Struvite; X-Ray Diffraction

To evaluate the factors that affect the enzymatic dissolution rate of calcium oxalate monohydrate (COM), calcium phosphate (brushite), and magnesium ammonium phosphate (struvite) crystals as enzymatic digestion of kidney stones could enhance lithotripsy or provide alternatives to surgical removal.. At pH 4.2, pelleted COM crystals were combined with oxalate decarboxylase (ODC from Bacillus subtilis), oxalate oxidase (from Hordeum vulgare), or control. Crystal dissolution was followed by measuring increases in solution calcium ion concentration. For phosphate-based crystals, the rates of phosphorolysis by the enzyme purine nucleoside phosphorylase (PNP, assay form) were compared to the control solution using spectrophotometry.. The addition of ODC to COM crystals resulted in production of highly soluble calcium formate and a 15-fold increase in COM solubility. By adding a formate-catabolizing enzyme (formate dehydrogenase), dissolution increased 47-fold compared with controls with nearly one half of the mineral dissolved. Oxalate oxidase showed much lower activity than ODC in COM dissolution. Using inorganic phosphate as a substrate, PNP was able to dissolve both brushite and struvite minerals in water at concentrations near saturation. Measuring dissolution by adding more PNP was not possible because of equilibrium and assay detection restraints.. Stone dissolution using enzymes appears to be viable, particularly for oxalate-based minerals. In a closed system, product inhibition by calcium formate appeared to limit the extent of COM crystal dissolution using ODC. Although phosphate-containing minerals appear to be suitable phosphate sources for PNP, the reversibility of the reaction limits the use of this enzyme.

Topics: Calcium Oxalate; Calcium Phosphates; Carboxy-Lyases; Humans; In Vitro Techniques; Kidney Calculi; Magnesium Compounds; Oxidoreductases; Phosphates; Purine-Nucleoside Phosphorylase; Solubility; Struvite

The Rietveld method is one of the most innovative and most important applications in x-ray diffraction and has now, for the first time, been applied to standard-free precise quantitative crystallographic analysis of urinary stones.. The capability of the Rietveld method was demonstrated by analysis of a synthetic mixture of five typical urinary stones: whewellite, hydroxylapatite, brushite, struvite, and uric acid, with 20 weight % for each pure component.. The quantitative phase analysis (Rietveld method) yielded a mean absolute error of only 1.6% for the weight fractions of the single urinary stone components. The largest error in weight fraction, 2.3%, occurred with hydroxylapatite, caused by the typical insufficient crystallinity.. Crystallographic analysis of complex urinary stones with the aid of x-ray diffraction, in combination with a Rietveld structure refinement, is the method of first choice for qualitative and quantitative phase analysis. With this tool, significant changes in weight fractions for recurrent urinary stones can be precisely detected, with therapeutic consequences.

Topics: Calcium Oxalate; Calcium Phosphates; Crystallography, X-Ray; Durapatite; Humans; Magnesium Compounds; Phosphates; Predictive Value of Tests; Recurrence; Risk Factors; Struvite; Uric Acid; Urinary Calculi

Mechanical properties of renal calculi dictate how a stone interacts and disintegrates by shock wave or intracorporeal lithotripsy techniques. Renal stones of different compositions have large variation in their mechanical strength and susceptibilities to shock waves. Operated urinary stones and artificially developed stones using pharmaceutical methods, composed of phosphates were subjected to tensile, flexural and compressive strength studies using universal testing machine. The infrared spectra confirmed the presence of hydroxyapatite in both the natural stones and struvite with calcium oxalate trihydrate in one stone and struvite with uric acid in the other. The X-ray diffraction analyses confirmed their crystalline nature. It has been observed that the flexural properties depend on the size of the sample even for the samples cut from a single stone. The compressive strengths were almost 25 times larger than the tensile strengths of the respective natural stones as well as the artificial stones prepared.

Topics: Biomechanical Phenomena; Calcium Oxalate; Calcium Phosphates; Durapatite; Humans; Lithotripsy; Magnesium Compounds; Materials Testing; Phosphates; Spectrophotometry, Infrared; Struvite; Tensile Strength; Urinary Calculi; X-Ray Diffraction

To derive hardness factors for crystal phases of urinary tract stones and describe the hardness pattern in a stone population.. In a retrospective study, recordings from patients treated with extracorporeal shock-wave lithotripsy (ESWL) (stone surface area < or = 100 mm2) were used to derive hardness factors. The number of re-treatments, the number of shock waves and the energy index (the voltage in kilovolts multiplied by the number of shock waves) required for a satisfactory stone disintegration were assumed to reflect the hardness. The stone composition in 2100 patients provided the basis for an average hardness pattern. A hardness index was calculated from the fraction of each crystal phase and its hardness factor.. The hardness factors were as follows: calcium oxalate monohydrate, 1.3; calcium oxalate dehydrate, 1.0; hydroxyapatite, 1.1; brushite, 2.2; uric acid/urate, 1.0; cystine, 2.4; carbonate apatite, 1.3; magnesium ammonium phosphate, 1.0; and mixed infection stones, 1.0. The hardness index for 114 stones (surface area 100-200 mm2) corresponded reasonably well to the ESWL treatment efforts. Calcium oxalate monohydrate, calcium oxalate dihydrate and hydroxyapatite were the most frequently encountered crystal phases in all 2100 stones. Only 21% of the stones were composed of only one crystal phase. There were two, three and more than three crystal phases in 26%, 38% and 15% of the stones, respectively. The hardness index calculated for 2100 stones ranged between 0.70 and 2.33, with a mean (SD) of 1.18 (0.15).. The hardness factors and hardness index derived in this study might be useful for describing the stone situation in individual patients and groups of patients and for comparison of various treatment strategies.

Topics: Apatites; Calcium Oxalate; Calcium Phosphates; Cystine; Durapatite; Hardness; Humans; Lithotripsy; Magnesium Compounds; Phosphates; Retrospective Studies; Struvite; Uric Acid; Urinary Calculi; Urinary Tract Infections

The aim of this study was to evaluate the efficacy of helical CT using a combination of CT-attenuation values and visual assessment of stone density as well as discriminant linear analysis to predict the chemical composition of urinary calculi. One hundred human urinary calculi were obtained from a stone-analysis laboratory and placed in 20 excised pig kidneys. They were scanned at 80, 120 and 140 kV with 3-mm collimation. Average, highest and lowest CT-attenuation values and CT variability were recorded. The internal calculus structure was assessed using a wide window setting, and visual assessment of stone density was recorded. A stepwise discriminant linear analysis was performed. The following three variables were discriminant: highest CT-attenuation value, visual density, and highest CT-attenuation value/area ratio, all at 80 kV. The probability of correctly classifying stone composition with these three variables was 0.64, ranging from 0.54 for mixed calculi to 0.69 for pure calculi. The probabilities of correctly classifying calculus composition were: 0.91 for calcium oxalate monohydrate and brushite, 0.89 for cystine, 0.85 for uric acid, 0.11 for calcium oxalate dihydrate, 0.10 for hydroxyapatite, and 0.07 for struvite calculi. When the first two ranks of highest probability for the accurate classification of each calculus type were taken into account, 81% of the calculi were correctly classified. Assessment at 80 kV of the highest CT-attenuation value, visual density and the highest CT-attenuation value/area ratio accurately predicts the chemical composition of 64-81% of urinary calculi. When the first two ranks of highest probability for the accurate classification of each calculus type were taken into account, all cystine, calcium oxalate monohydrate and brushite calculi were correctly classified.

Topics: Animals; Calcium Oxalate; Calcium Phosphates; Cystine; Discriminant Analysis; Durapatite; Humans; Magnesium Compounds; Phosphates; Predictive Value of Tests; Struvite; Swine; Tomography, Spiral Computed; Uric Acid; Urinary Calculi; Urography

The Twinheads extracorporeal shock wave lithotriptor (THSWL) is composed of 2 identical shock wave generators and reflectors. One reflector is under the table and the other is over the table with a variable angle between the axes of the 2 reflectors. The 2 reflectors share a common second focal point, making it possible to deliver an almost synchronous twin pulse to the targeted stone. We studied the optimal parameters for in vitro stone fragmentation.. Two types of 1 cm artificial stones were used, namely Bon(n)-stones of 3 compositions (75% calcium oxalate monohydrate [COM] plus 25% uric acid, struvite and cystine) and plaster of Paris. The parameters tested were shock wave number (100, 500 and 1,000), shock wave power (8, 11 and 14 kV) and angle between the reflector axes (67, 90 and 105 degrees). After the optimal parameters were determined we studied the disintegrative efficacy of THSWL for 3 types of human urinary calculi, including COM, calcium hydrogen phosphate (brushite) and cystine. Each stone received 1,000 twin shock waves at 14 kV with an angle of 90 degrees between the reflectors. All experiments were done using a rate of 60 twin shock waves per minute. Following lithotripsy stone fragments were processed and sized. The ratio of the weight of fragments greater than 2 mm-to-total weight of all fragments was calculated.. Optimal stone fragmentation results for THSWL were obtained with the maximum number of shock waves (1,000) and full power (14 kV). There was no significant statistical difference in fragment size or the ratio of fragments greater than 2 mm with the use of different angles except for cystine and plaster of Paris calculi, for which the right angle was most effective. At application of the optimal parameters to human stones THSWL produced small fragment size for COM and cystine stones, while brushite stones were not fragmented to the same extent.. The efficacy of synchronous twin pulse technology improves as the number of shock waves and power increase. A 90-degree angle between the shock wave reflectors is advantageous for certain stones (that is cystine and plaster of Paris) but it is not a factor for other stone compositions. THSWL has satisfactory disintegrative efficacy for human stones, especially COM and cysteine calculi.

Topics: Calcium Oxalate; Calcium Phosphates; Calcium Sulfate; Cystine; Humans; In Vitro Techniques; Lithotripsy; Magnesium Compounds; Particle Size; Phosphates; Struvite; Technology Assessment, Biomedical; Uric Acid; Urinary Calculi

We investigated the applicability of solid-state nuclear magnetic resonance (NMR) spectroscopy to obtain information about the structure and composition of renal calculi.. Various types urinary and bladder stones as well as a variety of presumed constituents were investigated using 13C and 31P magic-angle spinning (MAS) solid-state NMR. Different experimental methods were applied to differentiate resonances from crystalline/amorphous (immobile/mobile) as well as protonated/non-protonated moieties. The NMR spectra were analyzed using multiple-component numerical simulations and iterative fitting to identify and quantify the major amorphous or crystalline organic and inorganic components.. By comparison of the NMR spectra for the various renal calculi with those obtained under similar conditions for various presumed components, it is demonstrated possible to unambiguously distinguish and quantify the major amorphous or crystalline organic and inorganic components. The components are identified in terms of their isotropic and anisotropic chemical shielding parameters, protonation or proximity of protons, and the degree of crystallinity/mobility. For the calculi investigated we have detected and quantified calcium oxalate, uric acid, struvite, and calcium phosphates that closely resemble brushite and calcium hydroxyapatite.. Using 13C and 31P MAS NMR spectroscopy we have been able to account for 60 to 85% (by weight) of the constituents in the calculi investigated. The ability to identify and quantify both crystalline and amorphous components makes solid-state NMR an interesting new method for the compositional analysis of renal calculi.

Topics: Calcium Oxalate; Calcium Phosphates; Carbon Isotopes; Computer Simulation; Crystallography; Durapatite; Electron Spin Resonance Spectroscopy; Humans; Kidney Calculi; Magnesium Compounds; Magnetic Resonance Spectroscopy; Models, Chemical; Phosphates; Phosphorus Isotopes; Struvite; Uric Acid; Urinary Bladder Calculi

To determine extent and nature of regional differences in distribution of canine urinary calculi.. 13,552 calculus specimens: 7,056 (52.1%) from females, 6,492 (47.9%) from males, and 4 from dogs of unrecorded sex. Procedure Records were used to compile information from all specimens submitted between July 1981 and December 1995. Results from mixed-breed and various breeds of stone-forming dogs were analyzed. Interrelations of breed, sex, and age of dogs, and anatomic location and mineral composition of specimens were analyzed and compared for 6 US geographic regions.. Struvite-, apatite-, and urate-containing calculi were reported significantly most often from female dogs of the Mountain/Pacific region. Oxalate-, silica-, and brushite-containing calculi were reported significantly most often from male dogs in the New England/mid-Atlantic (NEMA) region. Cystine-containing calculi were reported most frequently from the NEMA and South Central (SC) regions. Dogs from the NEMA region were oldest in average age at diagnosis. Significant regional differences in distribution were found for several breeds. Sex distribution of renal calculi in 11 breeds of dogs (Lhasa Apso, Yorkshire Terrier, Shih Tzu, Basset Hound, Pug, Mastiff, Bichon Frise, Doberman Pinscher, Dalmatian, English Bulldog, and Pekingese) reported to be at high risk of renal lithiasis differed among the 6 geographic regions. Renal and ureteral calculi were reported significantly most often from dogs in the South Atlantic region, and bladder and urethral calculi were reported most often from dogs in the SC region.. Wide regional differences exist in distribution of stone-forming dogs by sex, average age at diagnosis, breed, and minerals contained within and anatomic location of calculi.

Topics: Age Factors; Animals; Apatites; Breeding; Calcium Phosphates; Cystine; Dog Diseases; Dogs; Female; Magnesium Compounds; Male; Odds Ratio; Oxalates; Phosphates; Retrospective Studies; Risk Factors; Sex Factors; Silicon Dioxide; Struvite; United States; Uric Acid; Urinary Calculi

Phosphates precipitating from artificial urine in the pH range 6-8 were identified using X-ray diffraction, chemical analysis and scanning electron microscopy. The influence of magnesium and citrate on phases precipitating from urine was established. From urine containing a normal quantity of magnesium (around 70 ppm), brushite accompanied by hydroxyapatite (HAP) precipitated at pH < or = 7.0 and struvite with HAP at pH > 7.0. HAP was formed exclusively from magnesium deficient urine at pH 7.0. Newberyite, octacalcium phosphate and whitlockite were not identified. The chemical and phase composition and inner fine structure of 14 phosphate calculi were studied. Three types of stones were distinguished based on their magnesium content: (i) stones rich in magnesium composed of struvite, hydroxyapatite and abundant organic matter, (ii) stones with low magnesium content constituted by calcium deficient hydroxyapatite, up to 5% of struvite, considerable amount of organic matter and occasionally brushite, and (iii) calculi without magnesium consisting of brushite, hydroxyapatite and little organic matter. Conditions prevaling during stone-formation assessed for each type of stone were confirmed by corresponding urinary biochemical data and corroborate the in vitro studies of phosphates precipitation.

Topics: Calcium Phosphates; Chemical Precipitation; Crystallization; Kidney Calculi; Magnesium Compounds; Phosphates; Struvite

Most staghorn calculi are infection stones composed of struvite and/or carbonate apatite. Sometimes, cystine, uric acid, whewellite and brushite stones also assume a staghorn configuration when located in the kidney. It is very important in stone crushing to know the composition and architecture of the stones. Struvite stones show a concentric laminal structure and are fragile because of wide interstices of crystals and rich organic matrix. These stones usually contain many bacterial colonies in the interstices of crystals and bacteria break out of the stones when they are crushed. Therefore, perioperative administration of antibiotics is necessary for prevention of bacteremia and sepsis. Whewellite stones and uric acid stones have a smooth surface and reveal compact radial and laminal structure especially in the peripheral layer. They are very hard and are refractory to crushing, and the fragments are large. Cystine stones show a compact radial monomineral texture and are very hard. The fragments made by crushing are large. Therefore, combination therapy of stone crushing and irrigation of alkali solution may be useful for treatment of cystine stones as well as uric acid stones. Calcium phosphate stones, hydroxyapatite or brushite stones, are rare and are formed in hyperparathyroidism, Cushing syndrome and renal tubular acidosis. Hydroxyapatite stones are rich in matrix and fragile. Brushite stones reveal radiate structure and are hard. There is no general method of treatment for staghorn calculi but we should select the most reasonable method including open surgery for each case taking into consideration the stone composition, predisposing factors and possibility of stone residue and recurrence.

Topics: Apatites; Calcium Phosphates; Cystine; Humans; Kidney Calculi; Lithotripsy; Magnesium Compounds; Phosphates; Struvite; Uric Acid

Metallic stents have been used in the management of prostatic disease in patients unfit for surgery. A variety of stents have become available but the optimum design and metal of construction has not yet been defined. This study examined one of the potential complications of stent insertion by demonstrating that they are susceptible to encrustation. Using an in vitro model it compares the ability of the different materials used in their construction to resist this encrustation. Titanium appears less able to resist deposition than the other metals examined. The long-term complication of encrustation may inhibit the use of some of these stents.

Topics: Calcium Phosphates; Equipment Safety; Foreign-Body Reaction; Gold; Humans; Magnesium; Magnesium Compounds; Male; Microscopy, Electron, Scanning; Phosphates; Prostatic Diseases; Spectrophotometry, Infrared; Stainless Steel; Stents; Struvite; Titanium; Urethra; Urine

The composition and structure of 48 canine cystine urinary stones were determined by infrared spectroscopy, scanning electron microscopy and electron dispersive X-ray analysis. The infrared analysis showed that about 45% of the specimens were composed of pure cystine. The remainder also contained calcium oxalate (mono and/or dihydrate), magnesium ammonium phosphate hexadydrate (struvite), calcium hydrogen phosphate dihydrate (brushite) and complex urates (ammonium, ammonium potassium and/or potassium enriched ammonium urate). The infrared study of several samples heated at 620 degrees C and 750 degrees C revealed the presence of apatitic calcium phosphate. This compound was difficult to detect in the spectrum of the original samples due to the small proportion of phosphate contained in the calculi and to band overlapping. The examination of a series of selected samples by means of scanning electron microscopy and energy dispersive X-ray analysis complemented the infrared results.

Topics: Animals; Apatites; Calcium Oxalate; Calcium Phosphates; Cystine; Dog Diseases; Dogs; Electron Probe Microanalysis; Magnesium; Magnesium Compounds; Male; Microscopy, Electron, Scanning; Phosphates; Spectrophotometry, Infrared; Struvite; Uric Acid; Urinary Calculi

The internal-standard method and the powder diffractometer have been applied here to the quantitative determination of urinary stone constituents by x-ray diffraction (XRD). Reference intensity ratios determined for six stone substances were used in the reduction of intensity data. Constituent concentrations calculated for 21 stones were compared with values obtained from an element-sensitive technique. We conclude that XRD analysis alone cannot be regarded as a routine technique for the quantitative characterization of uroliths, but that semiquantitative XRD analysis supplemented by accurate quantitative elemental data is more suitable for the precise determination of true stone composition.

Topics: Calcium Oxalate; Calcium Phosphates; Durapatite; Humans; Hydroxyapatites; Magnesium; Magnesium Compounds; Phosphates; Struvite; Uric Acid; Urinary Calculi; X-Ray Diffraction

Topics: Apatites; Calcium Phosphates; Combined Modality Therapy; Humans; Kidney; Kidney Calculi; Magnesium; Magnesium Compounds; Oxalates; Phosphates; Struvite

The ESWL retreatment rates for calculi of 1.1 to 3.0 cm. varied according to stone composition: calcium oxalate monohydrate (COM) 10.3%, calcium oxalate dihydrate (COD) 2.8%, struvite/apatite calculi 6.4%. Fine detail in-vitro radiographs of approximately equal sized calculi composed of COM, COD, struvite, brushite, uric acid and cystine showed structural differences which may account for differences in their fragility. The same six calculi were fragmented in vitro in the Dornier HM3 lithotriptor by 200 shocks at 18 KV and the percent weight of each calculus able to be filtered through a two mm. sieve was determined; COD and uric acid (100%); COM (64%); struvite (57%); brushite (47%); cystine (16%). The linear density of these calculi, measured by single photon emission absorbtiometry, correlated with radio-density, not fragility. Calculi of varying composition respond differently to shock wave fragmentation. The assessment of the capability of ESWL to fragment a stone will determine the size stone selected for treatment. Therefore, "stone fragility" is a new distinction which deserves to be included in the conversation about urinary calculi.

Topics: Calcium Oxalate; Calcium Phosphates; Cystine; Humans; Kidney Calculi; Lithotripsy; Magnesium; Magnesium Compounds; Phosphates; Struvite; Uric Acid

This article contains an analysis of data compiled from 813 specimens of canine uroliths submitted to the Urinary Stone Analysis Laboratory at University of California School of Veterinary Medicine.

Topics: Animals; Apatites; Calcium Phosphates; Cystine; Cystinuria; Dog Diseases; Dogs; Magnesium; Magnesium Compounds; Minerals; Oxalates; Phosphates; Silicon Dioxide; Struvite; Uric Acid; Urinary Calculi

From the analysis of various urinary constituents and the estimation of urinary saturation of stone-forming salts, it is now possible to identify risk factors responsible for or contributing to stone formation. Metabolic factors included calcium, oxalate, uric acid, citrate and pH. Environmental factors were total volume, sodium, sulfate, phosphate and magnesium. Physicochemical factors represented saturation of calcium oxalate, brushite, monosodium urate, struvite and uric acid. A scheme for graphic display of risk factors was developed to allow ready visual recognition of important risk factors presumed to cause stone formation. This graphic display had diagnostic use as well as practical value in following response to treatment. For example, a low urinary pH and high urinary concentration of undissociated uric acid could be discerned readily in cases of uric acid lithiasis, as were high urinary pH and exaggerated urinary supersaturation of struvite in cases of infection lithiasis. In a patient with absorptive hypercalciuria and hypocitraturia treatment with thiazide and potassium citrate could be shown to abolish high risks (hypercalciuria, hypocitraturia and relative supersaturation of calcium oxalate) displayed before treatment.

Topics: Calcium; Calcium Oxalate; Calcium Phosphates; Citrates; Citric Acid; Humans; Hydrochlorothiazide; Hydrogen-Ion Concentration; Kidney Calculi; Magnesium; Magnesium Compounds; Oxalates; Oxalic Acid; Phosphates; Risk; Struvite; Uric Acid

Crystallization of struvite and calcium phosphates was studied in vitro as encrustations on glass rods immersed in synthetic urine, to evaluate the crystallization capacity of Ureaplasma urealyticum and compare it with that of known urease and non-urease-producing bacteria. Inoculation of the synthetic urine with Ureaplasma urealyticum resulted in alkalinization of the synthetic urine and crystallization of struvite and brushite. Inoculation with Proteus mirabilis caused a faster and more pronounced alkalinization as well as crystallization of struvite and apatite. The alkalinization and crystallization caused by Ureaplasma urealyticum and Proteus mirabilis was completely prevented by acetohydroxamic acid, a potent urease inhibitor, linking the crystallization to the urease activity of the microorganisms. When the synthetic urine was inoculated with urease-negative Escherichia coli no alkalinization and no crystallization were seen.

Topics: Calcium Phosphates; Crystallization; Escherichia coli; Hydrogen-Ion Concentration; Hydroxamic Acids; Magnesium; Magnesium Compounds; Phosphates; Proteus mirabilis; Struvite; Ureaplasma; Urease; Urine

Topics: Adult; Aged; Calcium Oxalate; Calcium Phosphates; Female; Humans; Hydroxyapatites; Magnesium; Magnesium Compounds; Male; Middle Aged; Phosphates; Struvite; Urinary Calculi; X-Ray Diffraction

Excised urinary calculi were subjected to computed tomographic (CT) scanning in an attempt to determine whether CT attenuation values would allow accurate analysis of stone composition. The mean, maximum, and modal pixel densities of the calculi were recorded and compared; the resulting values reflected considerable heterogeneity in stone density. Although uric acid and cystine calculi could be identified by their discrete ranges on one or more of these criteria, calcium-containing stones of various compositions, including struvite, could not be distinguished reliably. CT analysis of stone density is not likely to be more accurate than standard radiography in characterizing stone composition in vivo.

Topics: Calcium Oxalate; Calcium Phosphates; Cystine; Humans; Magnesium; Magnesium Compounds; Phosphates; Struvite; Tomography, X-Ray Computed; Uric Acid; Urinary Calculi

Quantitative analytical findings on upper urinary tract stones from 500 patients are reported and compared to data in the literature. Methods of presentation of quantitative data are discussed. A wide range of findings between recurrent stones in the same patient and between stones from patients with the same cause of stone formation was found. No immediate clinical value of quantitation can be seen, but larger materials and correlation with metabolic investigations in stone formers may reveal correlations of clinical interest. Quantitative observations may identify groups of patients and types of stones not recognised on the basis of qualitative analysis. Examples of this are given for calcium oxalate-calcium phosphate stones and for stones containing brushite. The organic matrix which usually contributes 2-3% of stone mass was not considered, but distinctly visible and separate organic material in 7 stones was quantitated by visual estimate. 32 stones were incomplete, and their quantitation may not be wholly representative. Their exclusion, however, would have led to major bias because most were large and nearly half were triple phosphate stones, both properties being relatively rare. In cases of multiple stones, usually only one was quantitated. Seventy patients provided more than one stone for analysis (Otnes, 1983b), but except when specifically stated only the first stone is considered.

Topics: Calcium Oxalate; Calcium Phosphates; Crystallization; Crystallography; Cystine; Humans; Magnesium; Magnesium Compounds; Phosphates; Recurrence; Struvite; Uric Acid; Urinary Calculi

The mineral composition of 103 stones from Iran was determined by a polarisation microscope and infrared spectroscopy. The commonest components were whewellite (81.5%), weddellite (40.7%), apatite (69%) and ammonium acid urate (24.4%). Ectopic cossification in the nuclei was found in three renal calculi (2.9%). Twenty-five stones were from children, where one of the most frequent patterns was formed by both ammonium acid urate and calcium oxalate. This suggests that a high proportion of the children from Iran with urolithiasis have nutritional disorders.

Topics: Adult; Calcium Oxalate; Calcium Phosphates; Child; Female; Humans; Hydroxyapatites; Iran; Kidney Calculi; Magnesium; Magnesium Compounds; Male; Microscopy, Polarization; Minerals; Phosphates; Spectrophotometry, Infrared; Struvite; Uric Acid; Urinary Bladder Calculi

The clinical management of renal calculi would be aided if a direct in vivo determination of stone chemical composition could be made. We investigated the possibility of obtaining this information by a quantitative analysis of the computerized tomography scan images of 80 urinary calculi. Our results show that by using an appropriately calibrated computerized tomography scanner the differentiation of stone chemical composition can be made on the basis of 3 parameters, namely, absolute computerized tomography value at a single x-ray energy, the difference between computerized tomography values measured at 2 different x-ray energies, and computerized tomography value-frequency histograms (pixel patterns) of the stones. Uric acid stones were differentiated from all other stones at a significance level of p less than 0.001. Cystine was differentiated from calcium oxalate and brushite at the same significance level. Using pixel patterns cystine and struvite were separated from each other correctly with 70 per cent accuracy. Struvite stones of low or moderate calcium phosphate content were identified correctly with 80 per cent accuracy. Struvite stones of high calcium phosphate content could not be differentiated from calcium oxalate or brushite. Calcium oxalate and brushite could not be separated. The minimum stone size that allowed chemical identification was established for each stone type. In addition, we demonstrated that all the urinary calculi examined were visible on computerized tomography scan regardless of chemical composition or size.

Topics: Calcium Oxalate; Calcium Phosphates; Cystine; Humans; Magnesium; Magnesium Compounds; Mathematics; Phosphates; Struvite; Tomography, X-Ray Computed; Urinary Calculi

Topics: Calcium Oxalate; Calcium Phosphates; Centrifugation, Density Gradient; Chemical Fractionation; Chemistry Techniques, Analytical; Humans; Hydroxyapatites; Magnesium; Magnesium Compounds; Phosphates; Struvite; Uric Acid; Urinary Calculi; X-Ray Diffraction

Topics: Apatites; Calcium; Calcium Phosphates; Calculi; Humans; Magnesium; Magnesium Compounds; Phosphates; Struvite; Urinary Calculi; Urinary Tract; Urine