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Query: UMLS:C0020500 (hyperoxaluria)
 912 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have provided evidence that an anaerobic bacterium, which degrades dietary oxalate to CO2 and formate, is present in colonic contents of a number of herbivorous species, laboratory rodents and humans. The present study examines the possibility that these bacteria degrade significant amounts of oxalate and can influence colonic oxalate absorption. Guinea pigs adapted to a diet containing 2% sodium oxalate or fed a normal diet were challenged with 67, 135, 170 or 200 mg of sodium oxalate containing 0.5 microCi of [14C]oxalate, which was injected into the cecum. Adapted animals excreted approximately 2% of the 14C in the urine, regardless of the dose, whereas unadapted animals excreted significantly higher amounts in the urine at the two lower doses and died at the two higher doses. Conversely, antibiotic treatment of adapted guinea pigs reduced the ability of their cecal flora to degrade oxalate, and a correspondingly greater percentage of an injected oxalate load was excreted in the urine. Oxalate degradation rates in cecal fluid were depressed by the secondary bile salt deoxycholate, and in vitro studies with pure isolates of guinea pig and human strains of oxalate degraders confirmed that these bacteria were highly sensitive to low concentrations of deoxycholate. Results indicate that these bacteria may be important in preventing excess absorption of oxalate and raise the possibility that the hyperoxaluria associated with bile salt malabsorption of ileal disease in part may be due to suppression of these bacteria by the bile salts.
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PMID:Intestinal oxalate-degrading bacteria reduce oxalate absorption and toxicity in guinea pigs. 337 43

Oxalate oxidase known to catalyse the aerobic oxidation of oxalic acid into CO2 and H2O2, has been found in bacteria, fungi, mosses and some higher plants. So far, a membrane bound oxalate oxidase from Pseudomonas sp. OX-53 and a soluble oxalate oxidase from seedling plants of barley and grain sorghum has been purified to homogeneity by conventional purification methods. The enzyme has been immobilized onto insoluble support such as nylon tubing, zirconia coated alkylamine glass, polyamide membrane, CO2 gas sensing electrode, H2O2 sensor probe and polyanionic electrolyte such as ethylaminemaleic anhydride (EMA). Compared to free enzyme the immobilized enzyme showed an increase in optimum pH, decrease in Vmax and time for maximum activity, higher resistance to inhibition by NaCl but no change in Km value. The immobilized enzyme has been used in both continuous flow system and discrete assays and in enzyme electrode for determination of oxalate in urine, blood and food stuff, which is essentially required for the diagnosis and treatment of hyperoxaluria and calcium oxalate urinary stones. The degradation of endogenous oxalate in rat by immobilized oxalate oxidase has opened a new vistas in enzyme therapy of hyperoxaluria.
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PMID:Isolation, purification, immobilization of oxalate oxidase and its clinical applications. 818 50

Hyperoxaluria is a major risk factor for calcium oxalate kidney stones and the intestine is recognized as an important extra-renal pathway for eliminating oxalate. The membrane-bound chloride/bicarbonate (Cl(-)/) exchangers are involved in the transcellular movement of oxalate, but little is understood about how they might be regulated. , CO2, and pH are established modulators of intestinal NaCl cotransport, involving Na(+)/H(+) and Cl(-)/ exchange, but their influence on oxalate transport is unknown. Measuring (14)C-oxalate and (36)Cl fluxes across isolated, short-circuited segments of the mouse distal ileum and distal colon we examined the role of these acid-base variables and carbonic anhydrase (CA) in oxalate and Cl(-) transport. In standard buffer both segments performed net oxalate secretion (and Cl(-) absorption), but only the colon, and the secretory pathway were responsive to and CO2. Ethoxzolamide abolished net oxalate secretion by the distal colon, and when used in tandem with an impermeant CA inhibitor, signaled an intracellular CA isozyme was required for secretion. There was a clear dependence on as their removal eliminated secretion, while at 42 mmol/L was also decreased and eradicated. Independent of pH, raising Pco2 from 28 to 64 mmHg acutely stimulated net oxalate secretion 41%. In summary, oxalate secretion by the distal colon was dependent on , CA and specifically modulated by CO2, whereas the ileum was remarkably unresponsive. These findings highlight the distinct segmental heterogeneity along the intestine, providing new insights into the oxalate transport mechanism and how it might be regulated.
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PMID:Effects of acid-base variables and the role of carbonic anhydrase on oxalate secretion by the mouse intestine in vitro. 2571 24