Oxidative stress in elderly chronic renal failure patients: effects of renal replacement therapies on cell membrane fluidity.

BACKGROUND: Renal replacement therapies (RRTs) produce a partial loss of antioxidants and formation of reactive oxygen species (ROS), which are a major factor involved in alterations of plasma membrane fluidity and endothelial activation, but their role on plasma membrane fluidity in vivo is still unclear. We compared erythrocyte plasma membrane fluidity, ROS and total plasma antioxidant defenses (Lagtime) in aged patients with chronic renal failure (CRF) on conservative treatment, peritoneal dialysis (PD) and hemodialysis (HD) before (HD-pre) and after (HD-post) a treatment, to evaluate the role of different RRTs on oxidative stress and plasma membrane fluidity in aged patients. METHODS: We assessed erythrocyte plasma membrane fluidity, plasma lipid hydroperoxide levels and Lag-Time in 11 CRF patients on conservative treatment, 15 on PD, 12 on HD and 30 healthy controls. RESULTS: Hydroperoxides were higher in CRF, PD and HD-post, whereas Lag-time was significantly lower in PD, CRF and in HD-post. CRF, PD and HD-pre also had higher membrane fluidity (rsDPH), compared with HD-post and controls. CONCLUSION: These findings are in keeping with the hypothesis that the Lag-time decrease is due not only to the effect of the RRT but also to the uremic state, and that PD patients undergo a chronic, greater oxidative stress. Contrary to expectations, all patients showed greater erythrocyte membrane fluidity, which can be attributed to uremic toxicity. These observations reinforce the hypothesis that oxidative stress is an intrinsic component of this disease state and indeed is already present also in CRF not yet requiring RRT.

Lysosomal leukocyte beta-D-glucuronidase during enzyme replacement therapy in Fabry disease.

OBJECTIVE: Fabry disease results from a deficiency in the activity of alpha-d-galactosidase A and subsequent accumulation of neutral glycosphingolipids in lysosomes. This study investigated whether lysosomal enzymes can indicate biochemical changes in the lysosomal apparatus induced by enzyme replacement therapy (ERT). DESIGN AND METHODS: Eight patients were monitored by clinical and biochemical tests and several lysosomal glycohydrolases were measured in plasma and leucocytes. RESULTS: Before starting ERT, beta-d-glucuronidase in leukocytes was markedly increased. After 1 month of therapy, enzyme levels dropped in all patients. In the patients who regularly followed the therapy, the enzyme levels remained stable for the next 20 months. In one patient who interrupted therapy for 2 months, the enzyme levels rose again. CONCLUSIONS: Lysosomal enzymes can be useful for monitoring biochemical changes in patients with Fabry disease receiving ERT. Though these findings refer to only a small number of patients, the correlation between beta-d-glucuronidase levels and ERT is interesting and might serve as a basis for further studies to define the potential of this enzyme in monitoring the effects of ERT in lysosomal storage disorders.