Cystatin C can be affected by nonrenal factors: a preliminary study on leukemia.

OBJECTIVE: The aim of this study was to evaluate the influence of malignancy and the impact of nephrotoxic drugs used in bone marrow transplantation (BMT) on the circulating levels of cystatin C in leukemia. METHODS: We studied nineteen patients (eleven men and eight women; mean age 30.1 +/- 11.2, 27.9 +/- 7.1 years) with acute lymphoblastic leukemia, acute myeloid leukemia and chronic myeloid leukemia. Cystatin C, urea, creatinine and creatinine clearance (CrCl) were measured 24 h before BMT, 1 week after BMT, 2 weeks after BMT and 3 weeks after BMT. The control group consisted of twenty healthy adults, and the mean age was 29.1 +/- 8.9. RESULTS: At the pretransplantation period, values of cystatin C were significantly higher than in the control group (P < 0.05). Urea, creatinine and CrCl values were not statistically different from the controls. One week after BMT, the level of cystatin C was significantly low as compared to the levels measured 24 h before BMT, but was still significantly higher than the controls (P < 0.05), whereas the levels of urea, creatinine and CrCl were in accordance with the levels of the controls. Two and three weeks after BMT, cystatin C values maintained the significant increase (P < 0.05), whereas the values of urea, creatinine and CrCl still corresponded with those of the controls in both group. CONCLUSIONS: Our preliminary data expose that cystatin C is not a reliable GFR marker in patients during leukemia or for monitoring nephrotoxic drugs used in BMT, but we can not reach definitive conclusion due to no gold standard for comparing the diagnostic accuracy of cystatin C. Further study is needed to elucidate the precise mechanism underlying this observation.

Effect of the sulphonylurea glibenclamide on liver and kidney antioxidant enzymes in streptozocin-induced diabetic rats.

BACKGROUND: Alterations in catalase (CAT) and superoxide dismutase (SOD) activity have been reported in diabetes mellitus. Glibenclamide (glyburide), a member of the second-generation sulphonylureas, provides effective treatment for patients with moderate diabetes. The action of the liver plays an important role in its glucose-lowering effect, suggesting that glibenclamide also exerts a direct effect on liver enzyme activities. OBJECTIVE: To evaluate the effect of glibenclamide on the activities of antioxidant enzymes (CAT and SOD) in liver and kidney tissue of diabetic rats. METHODS: Thirty-nine rats were included in this study. Moderate diabetes mellitus was induced with streptozocin (freshly dissolved in citrate buffer, ph 4.5) 55 mg/kg in 22 rats. Eight of these diabetic rats were left untreated, insulin was administered to six diabetic rats, and glibenclamide was administered to eight rats with moderate diabetes. Liver and kidney CAT and SOD activities were measured in all rats. RESULTS: Hepatic CAT and SOD activities were significantly reduced in diabetic animals (p < 0.05 for both activities). Glibenclamide treatment of diabetic rats for 5 weeks reversed the changes observed in diabetic liver tissues (p < 0.05). However, renal CAT and SOD activities were unchanged. In addition, high blood glucose levels of diabetic rats were decreased following glibenclamide treatment. CONCLUSION: Administration of glibenclamide to diabetic rats reversed diabetes-induced changes, suggesting that glibenclamide may directly increase liver CAT and SOD activity.