Navegando por Palavras-chave "Calcium oxalate"

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    Hyperoxaluria in a Model of Mini-Gastric Bypass Surgery in Rats
    (Springer, 2017) Ormanji, Milene S. [UNIFESP]; Korkes, Fernando [UNIFESP]; Meca, Renata [UNIFESP]; Ishiy, Crysthiane S. R. A. [UNIFESP]; Finotti, Gustavo H. C. [UNIFESP]; Ferraz, Renato R. N. [UNIFESP]; Heilberg, Ita P. [UNIFESP]
    Bariatric surgery is associated with hyperoxaluria hence predisposing to nephrolithiasis. The present study aimed to investigate the underlying mechanisms contributing to increased urinary oxalate in a mini-gastric bypass (MGB) surgery model in rats under different dietary conditions. The expression of intestinal oxalate transporters was also evaluated. Male rats underwent MGB (n = 21) or Sham procedure (n = 21) and after recovery were fed a standard or high-fat diet with or without oxalate for 8 weeks. Stool and urine were collected before surgery (baseline) and at the end of protocol (final), when intestinal fragments were harvested for expression of Slc26a3 and Slc26a6 oxalate transporters. MGB groups fed with fat, irrespective of oxalate supplementation, presented steatorrhea. In MGB animals fed with fat and oxalate (Fat + Ox), final values of urinary oxalate and calcium oxalate supersaturation risk were markedly and significantly increased versus baseline or Sham animals under the same diet, as well as MGB groups under other diets. Slc26a3 was decreased in biliopancreatic limbs of MGB rats, probably reflecting a physiological adaptation to the restriction of food passage. Slc26a6 was not altered in any harvested intestinal fragment. A high-fat and oxalate diet induced hyperoxaluria and elevation in calcium oxalate supersaturation risk in a MGB rat model. The presence of fat malabsorption and increased dietary oxalate absorption, but not modifications of Slc26a3 and Slc26a6 oxalate transporters, accounted for these findings, suggesting that bariatric patients may benefit from a low-fat and low-oxalate diet.
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    Simplified estimates of ion-activity products of calcium oxalate and calcium phosphate in mouse urine
    (Springer, 2012-08-01) Tiselius, Hans-Goran; Nogueira Ferraz, Renato Ribeiro [UNIFESP]; Heilberg, Ita Pfeferman [UNIFESP]; Karolinska Inst; Universidade Federal de São Paulo (UNIFESP)
    This study aimed at formulating simplified estimates of ion-activity products of calcium oxalate (AP(CaOx)) and calcium phosphate (AP(CaP)) in mouse urineto find the most important determinants in order to limit the analytical work-up. Literature data on mouse urine composition was used to determine the relative effect of each urine variable on the two ion-activity products. AP(CaOx) and AP(CaP) were calculated by iterative approximation with the EQUIL2 computerized program. the most important determinants for AP(CaOx) were calcium, oxalate and citrate and for AP(CaP) calcium, phosphate, citrate, magnesium and pH. Urine concentrations of the variables were used. A simplified estimate of AP(CaOx) (AP(CaOx)-index(MOUSE)) that numerically approximately corresponded to 10(8) x AP(CaOx) was given the following expression:AP(CaOx)-index(MOUSE) = 0.70 x Calcium(1.05) x Oxalate(0.95)(0.90-0.0225 x Citrate) + (6.6 x 10(-8) x Citrate(3.98))For a series of urine samples with various composition the coefficient of correlation between AP(CaOx)-index(MOUSE) and 10(8) x AP(CaOx) was 0.99 (p = 0.00000). A similar estimate of AP(CaP) (AP(CaP)-index(MOUSE)) was formulated so that it approximately would correspond numerically to 10(14) x AP(CaP) taking the following form:Ap(CaP)-index(MOUSE) = 0.05 x Calcium(1.17) x Phosphate(0.85) x Magnesium(0.18) x (pH - 4.5)(6.8) / Citrate(0.76)For a series of variations in urine composition the coefficient of correlation was 0.95 (p = 0.00000). the two approximate estimates shown in this article are simplified expressions of AP(CaOx) and AP(CaP). the intention of these theoretical calculations was not to get methods for accurate information on the saturation levels in urine, but to have mathematical tools useful for rough conclusions on the outcome of different experimental situations in mice. It needs to be emphasized that the accuracy will be negatively influenced if urine variables not included in the formulas differ very much from basic concentrations.