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PubMed1999

[The evaluation of methods for determinations of urinary oxalate].

BACKGROUND: Estimation of urinary oxalate is one of important tools for the diagnosis and treatment of urolithiasis. And more precise, simple and inexpensive method is desirable. In the present study, we evaluated three methods which were clinically well-used. METHODS: From October 1996 to June 1997, 146 acidified urine samples were collected for 24 hours from 144 urolithiasis patients. We determined the urinary oxalates by three methods; the colorimetric method, the enzymic method and the ion chromatography (IC method). And we evaluated the correlations of these methods. RESULTS: Correlation coefficients in the urine oxalate concentration were, 0.86 with the colorimetric method and the IC method, 0.91 with the enzymic method and the IC method, 0.90 with the colorimetric method and the enzymic method. The coefficients in the 24 hours-urinary excretion of oxalate (0.76, 0.87, 0.82) were lower than those in the urine oxalate concentration. The correlation coefficients with the colorimetric method and the IC method were, 0.58 in hyperoxaluric group, 0.34 in normooxaluric group. The coefficients with the enzymic method and the IC method, 0.93 in hyperoxaluric group, 0.71 in normooxaluric group. CONCLUSION: The colorimetric method is least expensive, but is less useful. The enzymic method is less expensive, and is as useful as the IC method.

Adolescent↗

PubMed1999

Evaluation of urinary and serum metabolites in Asian small-clawed otters (Aonyx cinerea) with calcium oxalate urolithiasis.

Baseline renal function data was collected during 24-hr periods of feeding and fasting from three male and three female adult Asian small-clawed otters (Aonyx cinerea) with calcium oxalate urolithiasis. Urine was analyzed for calcium, phosphorus, and oxalate, and urinalyses were performed. There was no evidence of glucosuria, which has been previously reported in Asian small-clawed otters with urolithiasis. Urinary oxalate levels were quite high when compared with those of dogs and humans without uroliths, and the ratio of urinary oxalate to calcium was close to 1:1 during periods of food consumption. There was no significant difference in urinary oxalate excretion between the fed and fasting states. Urinary calcium excretion was five times greater during feeding than during fasting. Calcium levels were higher in the otters than those reported for dogs without uroliths but were similar to those for normal humans. Water consumption and urine production were significantly higher during periods of food consumption. Serum chemistry analyses and electrolyte levels were also determined. There was no evidence of hypercalcemia. Fractional clearance of calcium and phosphorus and endogenous creatinine clearance were significantly higher during food consumption than during fasting. Parathyroid hormone levels were similar to those reported for dogs and cats. Serum 25-hydroxy-vitamin D was slightly lower in the otters than in dogs.

Animals↗

PubMed1992

Electrokinetic energy conversion studies of urine-oxalic acid systems across urinary bladder membrane.

Electrokinetic studies of urine-oxalic acid systems with increasing concentration of oxalic acid in urine have been carried out across urinary bladder membranes. It has been found that electro-osmotic flux and streaming current decrease with increase in concentration of oxalic acid in urine while hydrodynamic flux and streaming potential increase with increase in concentration. Kinetic energy term (alpha 1) and polarizability term (alpha 2) have been computed for these systems and it has been found that polarizability decreases much faster with increase in concentration of oxalic acid in urine. Electrokinetic energy conversion of these systems have been computed and it has been found that electrokinetic energy conversion is maximum for urine and it decreases with increase in concentration of oxalic acid in urine. Poor energy conversion may lead to sluggish flushing action which may ultimately lead to formation of urinary calculi in the bladder and so present study may be of some use in predicting electrophysiology of the bladder.

Animals↗

PubMed1991

Effects of ferric and aluminum oxalates on dentin permeability.

The purpose of this study was to compare the efficacy of ferric oxalate, aluminum oxalate, or Tenure dentin conditioner, a marketed product containing aluminum oxalate, at reducing the permeability of human dentin in vitro. Topical treatment with these acidified agents or 2.5% nitric acid for 10, 30, or 60 seconds was compared. The results indicate that 10-second treatments of dentin with all agents increased dentin permeability. Extending the treatment to 30 seconds produced a decrease in dentin permeability for acidified aluminum and ferric oxalate with 60-second treatments being even more effective. Treatment with Tenure dentin conditioner for 60 seconds did not reduce dentin permeability as well as treatment with the other oxalate salts.

Dentin Permeability↗

PubMed1986

Changes in urinary composition of calcium oxalate stone formers.

Calcium oxalate is the most important constituent of urinary calculi and the excretion pattern of calcium and oxalate is not consistent with stone formation. The increase in urinary calcium and oxalate in calcium oxalate stone formers has been found to be associated with the increase in uric acid and uromucoids along with the increase in inorganic phosphate and magnesium (in adults only) whilst citrate was decreased (in children only). The role of uric acid and uromucoids in the genesis of calcium oxalate stone is indicated.

Adolescent↗

PubMed1985

Stability of ascorbate in urine: relevance to analyses for ascorbate and oxalate.

Ascorbate is unstable in urine at room temperature at pH values ranging from 1 to 12. At pH 7 and above, oxalate is generated in amounts directly proportional to the ascorbate concentration. In 12 different urines, adjusted to pH 12 and incubated for 20 h at room temperature, there was a significant correlation between the amount of oxalate formed and the initial ascorbate concentration (r = 0.97, p less than 0.01). The mean (+/- SD) concentration of oxalate (1.32 +/- 0.70 mmol/L) formed during this period approximated the initial ascorbate concentration (1.57 +/- 1.09 mmol/L). Disodium EDTA, 10 mmol/L final concentration, stabilizes ascorbate in urine and inhibits its conversion to oxalate at pH values of 4.4 to 7.0 during a 24-h period. We therefore propose that urine specimens for ascorbate and oxalate analyses be collected with disodium EDTA present such as to give about this final concentration.

Ascorbic Acid↗

PubMed1983

Critical role of oxalate restriction in association with calcium restriction to decrease the probability of being a stone former: insufficient effect in idiopathic hypercalciuria.

The probability of being a stone former (PSF) was calculated according to the method of Robertson in three groups of idiopathic calcium stone formers (normocalciuria (NCa), dietary hypercalciuria (DH) and idiopathic hypercalciuria (IH] during four conditions: on a free diet; on a calcium and oxalate restricted diet for four days and after an oxalate load (200 g of spinach) while on a calcium unrestricted or calcium restricted diet. Combined calciuria (Ca) and oxaluria (Ox) restriction significantly decreased PSF only in NCa and DH whereas the decrease was not significant in IH because of a concomitant significant increase in oxalate excretion. Increase of PSF with the oxalate load was significantly greater on calcium restricted than on calcium unrestricted diets in all groups of patients (4-6-12 times greater in NCa, DH and IH respectively). This shows the critical role of oxalate restriction when calcium is restricted in order to decrease the PSF. Combined restriction is not sufficient in idiopathic hypercalciuric patients to decrease their probability of stone formation.

Calcium↗

PubMed1983

Reduction of elevated plasma oxalic acid by pyridoxine therapy in patients on RDT.

In eight chronic haemodialysed patients with secondary hyperoxalaemia due to renal insufficiency vitamin B6, an important co-enzyme in oxalic acid metabolism, was administered. Mean plasma oxalic acid values decreased from 149.5 +/- 67.0 mmol/L to 99.0 +/- 36.4 mmol/L within two weeks and to 93.8 +/- 33.1 mmol/L after four weeks of pyridoxine treatment (p less than 0.01, p less than 0.01). The mean reduction was 46 per cent (32.0 to 56.1). Patients with high pre-values of plasma oxalic acid had the most pronounced decrease. In order to prevent calcium oxalate deposition a reduction of plasma oxalic acid in patients on RDT seems to be an important goal in long term haemodialysis treatment.

Dose-Response Relationship, Drug↗

PubMed1980

Effect of sodium copper chlorophyllin on the formation of calcium oxalate crystals in rat kidney.

We induced the deposition of calcium oxalate crystals in rat kidney by intraperitoneal administration of 4-hydroxy-L-proline or sodium oxalate and studied the amounts and size distribution characteristics of the deposited crystals. Intravenous administration of sodium copper chlorophyllin inhibited the deposition and growth of calcium oxalate crystals induced by 4-hydroxy-L-proline or sodium oxalate. This finding may be of importance in calcium oxalate urolithiasis.

Animals↗

PubMed2001

Calcium oxalate crystals in tomato and tobacco plants: morphology and in vitro interactions of crystal-associated macromolecules.

Plants form calcium oxalate crystals with unique morphologies under well-controlled conditions. We studied the morphology of single calcium oxalate monohydrate (whewellite) crystals extracted from tomato and tobacco leaves. These crystals have a pseudotetrahedral shape. We identified the (101), (101) or (102), (110), and (hk0) faces as stable faces. The morphology is chiral with unique handedness. We also show that calcium oxalate monohydrate crystals isolated from tomato, tobacco, and bougainvillea leaves contain macromolecules rich in Gly, Glx, and Ser. Crystal-associated macromolecules extracted from tomato and tobacco influence the morphology of calcium oxalate monohydrate crystals grown in vitro, promoting preferential development of the [120] faces. Furthermore, crystal-associated macromolecules from tobacco promote nucleation of calcium oxalate monohydrate crystals, whereas model polypeptides do not have any significant effect on nucleation. These results imply an active role of the crystal-associated macromolecules in the formation of pseudotetrahedral shapes in vitro, and these properties may in part be responsible for the unique chiral morphology of the natural pyramidal-shaped crystals.

Calcium Oxalate↗

PubMed2005

Crystal structures and topological aspects of the high-temperature phases and decomposition products of the alkali-metal oxalates M2[C2O4] (M=K, Rb, Cs).

The high-temperature phases of the alkali-metal oxalates M2[C2O4] (M = K, Rb, Cs), and their decomposition products M2[CO3] (M = K, Rb, Cs), were investigated by fast, angle-dispersive X-ray powder diffraction with an image-plate detector, and also by simultaneous differential thermal analysis (DTA)/thermogravimetric analysis (TGA)/mass spectrometry (MS) and differential scanning calorimetry (DSC) techniques. The following phases, in order of decreasing temperature, were observed and crystallographically characterized (an asterisk denotes a previously unknown modification): *alpha-K2[C2O4], *alpha-Rb2[C2O4], *alpha-Cs2[C2O4], alpha-K2[CO3], *alpha-Rb2[CO3], and *alpha-Cs2[CO3] in space group P6(3)/mmc; *beta-Rb2[C2O4], *beta-Cs2[C2O4], *beta-Rb2[CO3], and *beta-Cs2[CO3] in Pnma; gamma-Rb2[C2O4], gamma-Cs[C2O4], gamma-Rb2[CO3], and gamma-Cs2[CO3] in P2(1)/c; and delta-K2[C2O4] and delta-Rb2[C2O4] in Pbam. With respect to the centers of gravity of the oxalate and carbonate anions, respectively, the crystal structures of all known alkali-metal oxalates and carbonates belong to the AlB2 family, and adopt either the AlB2 or the Ni2In arrangement depending on the size of the cation and the temperature. Despite the different sizes and constitutions of the carbonate and oxalate anions, the high-temperature phases of the alkali-metal carbonates M2[CO3] (M = K, Rb, Cs), exhibit the same sequence of basic structures as the corresponding alkali-metal oxalates. The topological aspects and order-disorder phenomena at elevated temperature are discussed.

Carbonates↗

PubMed1975

Growth of calcium oxalate in gel systems.

Methods are described for growing calcium oxalate in silica and gelatin gels under different conditions. The results obtained indicate that, in silica gel, calcium oxalate grows into single individual crystals, twins, and rosettes. Bipyramidal calcium oxalate dihydrate crystals similar to those present in the urine of stone formers were prepared in the silica gel system. The gelatin gel offered a suitably structured substrate on which calcium oxalate monohydrate crystals grow into aggregates. The orientation pattern of calcium oxalate crystals suggests that the growth process is controlled by the stereospecificity of the gelatin medium supporting growth.

Calcium↗

PubMed1982

Growth and characterization of calcium oxalate dihydrate crystals (weddellite).

Conditions are given for the growth of calcium oxalate dihydrate crystals (weddellite) in aqueous solution. The crystals obtained were characterized by scanning electron microscopic, spectroscopic, and thermal methods. The dissolution kinetics and electrophoretic mobility were determined; the thermodynamically unstable calcium oxalate dihydrate had a higher dissolution rate and a lower zeta potential than the monohydrate and underwent a phase transformation into the more stable calcium oxalate monohydrate. The results obtained on the chemical stability and the surface charge of calcium oxalate dihydrate offered additional information for assessing the current theories on the formation of calcium oxalate renal stones.

Calcium Oxalate↗

PubMed1994

The role of oxalate in lignin peroxidase-catalyzed reduction: protection from compound III accumulation.

Reduction may be an important step in the degradation of some highly oxidized environmental pollutants by Phanerochaete chrysosporium. Lignin peroxidases (LiP) from P. chrysosporium are able to catalyze reductive reactions using veratryl alcohol (VA) as a mediator and either oxalate or EDTA as electron donors. Reduction of oxygen to superoxide, monitored by oxygen consumption, was used as a measure of the reductive activity of LiP. In the presence of EDTA, the rate of O2 reduction catalyzed by LiP decreased with time and increasing concentrations of H2O2. When oxalate replaced EDTA, LiP-catalyzed O2 reduction did not decrease with time, and increasing concentrations of H2O2 increased the duration and extent of O2 reduction. LiP was converted to the compound III state in the presence of EDTA, H2O2, and veratryl alcohol. When oxalate replaced EDTA, compound II was observed. The importance of the veratryl alcohol cation radical (VA.+) in the conversion of LiP compound III to active enzyme has been previously examined (D.P. Barr and S.D. Aust, 1994, Arch. Biochem. Biophys. 311, 378-382). We propose that rapid reduction of VA.+ by EDTA results in accumulation of LiP compound III and the loss of activity resulting in a decrease in LiP-catalyzed reduction reactions. Oxalate is less effective in reducing the VA.+, therefore, some VA.+ remains to convert compound III to active enzyme and maintain LiP-catalyzed reduction reactions. Thus oxalate, a normal secondary metabolite of P. chrysosporium, is a suitable candidate for mediating reduction reactions by LiP in vivo.

Edetic Acid↗

PubMed1976

Urinary oxalate in summer and winter in normal subjects and in stone-forming patients with idiopathic hypercalciuria, both untreated and treated with thiazide and/or cellulose phosphate.

Urinary oxalate excretion has been measured by a specific enzymatic method in normal subjects and stone formers with idiopathic hypercalciuria. In every group studied urinary oxalate was higher in the summer than in the winter. These differences were slight and not significant in normal subjects but were considerable and statistically significant in the stone formers both untreated and when treated with thiazide. Thiazides raise urinary oxalate only very slightly but cellulose phosphate leads to large rises in urinary oxalate both in the summer and the winter. The highest values of urinary oxalate were seen in the summer in patients treated with cellulose phosphate. The mean rise in this group was 70% above normal and this must be viewed with some anxiety.

Benzothiadiazines↗

PubMed1991

Effects of chondroitin sulphate, human serum albumin and Tamm-Horsfall mucoprotein on calcium oxalate crystallization in undiluted human urine.

The effects of physiological concentrations of chondroitin sulphate, human serum albumin and Tamm-Horsfall mucoprotein on the crystallization of calcium oxalate in undiluted, ultrafiltered human urine were investigated using particle size analysis and scanning electron microscopy. Neither the amount of oxalate required to induce detectable calcium oxalate crystal nucleation nor crystal morphology was affected by the presence of any of these macromolecules. Chondroitin sulphate had no effect on the amount of crystalline material deposited or on the size of the particles precipitated in response to a standard oxalate load. Human serum albumin slightly reduced the size of the crystal aggregates and caused a small increase in the amount of crystal matter precipitated. By contrast, Tamm-Horsfall mucoprotein significantly inhibited crystal aggregation and markedly increased the volume of matter deposited, although this could not be attributed to a promotion of solute precipitation. It was concluded that chondroitin sulphate, human serum albumin and Tamm-Horsfall mucoprotein cannot account for the inhibitory effects of macromolecules with a relative mass greater than 10 kDa in spun and filtered urine. Nonetheless, Tamm-Horsfall mucoprotein is likely to inhibit crystal aggregation in whole urine in vivo and may therefore be instrumental in preventing calcium oxalate stone formation.

Adult↗

PubMed1977

Hyperoxaluria and intestinal disease. The role of steatorrhea and dietary calcium in regulating intestinal oxalate absorption.

Hyperoxaluria was documented in patients with pancreatic insufficiency, adult celiac disease, regional enteritis after ileectomy and partial colectomy, and jejunoileal bypass. The degree of hyperoxaluria correlated directly with the severity of the steatorrhea and inversely with the dietary calcium content. High-calcium diets suppressed oxalate excretion to normal when fecal fat excretion was approximately 30 g/day or less. In patients with more severe steatorrhea, decreasing dietary fat and oxalate content further reduced urinary oxalate excretion. These data suggest that, while steatorrhea is the most important determinant for enhanced absorption of dietary oxalate, variations in dietary calcium content modulate the amount of oxalate absorbed.

Adult↗

PubMed2005

[Calcium oxalate stones and hyperoxaluria. What is certain? What is new?].

Approximately 4 million Germans suffer from stone disease. In the majority of cases (70-75%) it is calcium oxalate. Its pathophysiology is complex and comprises disorders such as hypercalciuria, hyperoxaluria, hypocitraturia, hyperuricosuria, and hypomagnesuria. These biochemical changes in urine are well known as "classic" risk factors of calcium oxalate stone formation. However, studies in the last decade showed that calcium oxalate stones are strongly related with other diseases or disorders such as overweight, hypertension, or a lack of oxalate-degrading bacteria in the gut. The evidence for these "new" risk factors in the literature is very strong. It is particularly important in regard to effective treatment and aftercare of patients with calcium oxalate stones to be familiar with both the "classic" and the new risk factors.

Calcium Oxalate↗