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

Accumulation of oxalate leads to hyperoxaluria and calcium oxalate nephrolithiasis in man. Since oxalate is a metabolic end product in mammals, the feasibility of its enzymic degradation has been tested in vivo in rats by administering exogenous oxalate oxidase. Oxalate oxidase, isolated from banana fruit peels, in its native form was found to be non-active at the physiological pH of the recipient animal. However, its functional viability in the recipient animal was ensured by its prior binding with ethylenemaleic anhydride, thus shifting its pH activity curve towards the alkaline range. Rats implanted with dialysis membrane capsules containing such immobilized oxalate oxidase in their peritoneal cavities effectively metabolized intraperitoneally injected [14C]oxalate as well as its precursor [14C]glyoxalate. The implantation of capsules containing coentrapped multienzyme preparations of oxalate oxidase, catalase and peroxidase led to a further degradation of administered [14C]oxalate in rats.
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PMID:Degradation of oxalate in rats implanted with immobilized oxalate oxidase. 394 4

Hyperoxaluria is a well-known cause of renal stone disease and in vitro studies have shown that oxalate crystals have a stimulatory effect on apoptosis of renal tubular epithelial cells. Total and partial ureteral obstruction also have an accelerating effect on apoptosis of renal tubular epithelial cells. The aim of the present study was to investigate the apoptotic effect of unilateral ureteral obstruction in the presence of hyperoxaluria on the rat kidney. Twenty-eight male Wistar rats were divided into four groups, with seven rats in each. The groups were named G1 (control), G2 (hyperoxaluric), G3 (obstructive) and G4 (hyperoxaluric + obstructive). G2 and G4 rats were given 1% ethylene glycol (a precursor for oxalates) in their drinking water. G1 and G2 rats underwent sham operation, while left proximal ureteral ligation with a 5-zero silk suture was performed on G3 and G4 animals. The rats were sacrificed 2 weeks after the operation; left nephrectomy was then performed. We searched for the apoptotic cells by direct immuno-peroxidase detection of digoxigenin-labeled genomic DNA. The mean +/- SD values of the apoptotic cell count was 0.86+/-0.90 in G1 and 4.33+/-3.81 in G2. The values for G3 and G4 were 30.17+/-16.85 and 302.67+/-184.45, respectively. We found a statistically significant difference between all groups (P < 0.001). When compared with the control group (G1), the mean apoptotic cell count was fivefold that of G2 and 35- and 351-fold those of G3 and G4, respectively. Our study demonstrated that hyperoxaluria with complete ureteral obstruction induces an excessive level of apoptosis, which is responsible for renal damage, and that ureteral obstruction is a more important factor for apoptosis than hyperoxaluria. Considering these data, we also believe that research studies for medical preventive measures must be considered for patients with ureteral obstruction and/or hyperoxaluria.
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PMID:Renal tubular apoptosis after complete ureteral obstruction in the presence of hyperoxaluria. 1101 58

Calcium oxalate monohydrate (COM) crystals are the commonest component of kidney stones. Oxalate and COM crystals in renal cells are thought to contribute to pathology via prooxidant events. Using an in vivo rat model of crystalluria induced by hyperoxaluria plus hypercalciuria [ethylene glycol (EG) plus 1,25-dihydroxycholecalciferol (DHC)], we measured glutathione and energy homeostasis of kidney mitochondria. Hyperoxaluria or hypercalciuria without crystalluria was also investigated. After 1-3 wk of treatment, kidney cryosections were analyzed by light microscopy. In kidney subcellular fractions, glutathione and antioxidant enzymes were measured. In mitochondria, oxygen consumption and superoxide formation as well as cytochrome c content were measured. EG plus DHC treatment increased formation of renal birefringent crystal. Histology revealed increased renal tubular pathology characterized by obstruction, distension, and interstitial inflammation. Crystalluria at all time points led to oxidative stress manifest as decreased cytosolic and mitochondrial glutathione and increased activity of the antioxidant enzymes glutathione reductase and -peroxidase (mitochondria) and glucose-6-phosphate dehydrogenase (cytosol). These changes were followed by a significant decrease in mitochondrial cytochrome c content at 2-3 wk, suggesting the involvement of apoptosis in the renal pathology. Mitochondrial oxygen consumption was severely impaired in the crystalluria group without increased mitochondrial superoxide formation. Some of these changes were also evident in hyperoxaluria at week 1 but were absent at later times and in all calciuric groups. Our data indicate that impaired electron flow did not cause superoxide formation; however, mitochondrial dysfunction contributes to pathological events when tubular crystal-cell interactions are uncontrolled, as in kidney stones disease.
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PMID:Renal oxidative vulnerability due to changes in mitochondrial-glutathione and energy homeostasis in a rat model of calcium oxalate urolithiasis. 1667 Apr 37