Karen J. Byer

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PURPOSE Current studies have provided evidence that exposure of renal epithelial cells to oxalate and calcium oxalate crystals induces lipid peroxidation and injures the cells. Since oxidant/antioxidant balance is likely to play a critical role, we determined the effect of antioxidant scavengers on production of free radicals and injury to LLC-PK1 and MDCK(More)
A number of animal models have been developed to investigate calcium oxalate (CaOx) nephrolithiasis. Ethylene glycol (EG)-induced hyperoxaluria in rats is most common, but is criticized because EG and some of its metabolites are nephrotoxic and EG causes metabolic acidosis. Both oxalate (Ox) and CaOx crystals are also injurious to renal epithelial cells.(More)
Inter-alpha-inhibitor and other bikunin-containing proteins are synthesized in relatively large quantities by the liver. These proteins function as Kunitz-type serine protease inhibitors and appear capable of inhibiting calcium oxalate (CaOx) crystallization in vitro. Preliminary studies have shown that renal tubular epithelial cells synthesize bikunin in(More)
Since hypercalciuria is a common feature of idiopathic calcium oxalate (CaOx) nephrolithiasis, renal epithelial cells of stone patients are exposed to various crystals in the presence of high calcium. This study was performed to determine the effect of high calcium levels on CaOx crystal-induced cell injury. We exposed human renal epithelial cell line, HK2(More)
Two renal epithelial cell lines, LLC-PK1 and Madin-Darby canine kidney (MDCK), were grown in monolayers and exposed to oxalate (Ox) and/or calcium oxalate (CaOx) crystals to investigate cellular responses to these challenges. In addition, LLC-PK1 cells were exposed to high concentrations of Ox for various time periods to investigate the role of apoptosis in(More)
PURPOSE Patients with calcium oxalate kidney stones are advised to decrease the consumption of foods that contain oxalate. We hypothesized that a cutback in dietary oxalate would lead to a decrease in the urinary excretion of oxalate and decreased stone recurrence. We tested the hypothesis in an animal model of calcium oxalate nephrolithiasis. MATERIALS(More)
BACKGROUND Exposure of renal epithelial cells to oxalate (Ox) or calcium oxalate (CaOx) crystals leads to the production of reactive oxygen species and cell injury. We have hypothesized that Ox and CaOx crystals activate NADPH oxidase through upregulation of its various subunits. METHODS Human renal epithelial-derived cell line, HK-2, was exposed to 100(More)
Teas prepared from the fruits of Ammi visnaga L. (syn. "Khella") have been traditionally used in Egypt as a remedy to treat kidney stones. It was the aim of our study to evaluate the effect of a Khella extract (KE) as well as the two major constituents khellin and visnagin on renal epithelial injury using LLC-PK1 and Madin-Darby-canine kidney (MDCK) cells.(More)
OBJECTIVE To determine the differences in cell responses to synthetic and biological crystals of calcium oxalate (CaOx) and brushite MATERIALS AND METHODS Nephrolithiasis depends on crystal retention within the kidneys, often promoted by crystal attachment to the injured renal epithelium; studies often use various crystals that might be injurious to cells(More)
BACKGROUND Crystal formation and retention are critical events for the formation of kidney stones. Oxalate and calcium oxalate (CaOx) crystals are injurious to renal epithelium, and membranes of injured cells promote crystal adherence and retention. Calcium phosphate (CaP) is the most common crystal in both urine and stones, most likely to form in the early(More)