Effects of a vitamin E-bonded membrane and of glutathione on anemia and erythropoietin requirements in hemodialysis patients.

BACKGROUND: The oxidative damage of RBC membranes in hemodialysis (HD) patients increases red blood cell (RBC) susceptibility to hemolysis and impairs cell survival. Reduction of the oxidative stress might lead to better control of anemia and reduction of the erythropoietin (rhEPO) dose. METHODS: We studied 38 stable HD patients, given a mean dose of rhEPO of 104+/-65 U/kg BW/week, at baseline and during antioxidant treatment with either a full or a 50% dose of EPO. Antioxidant treatment involved the combined use of glutathione, GSH (1200 mg i.v. at the end of each dialysis session) and a vitamin E-bonded HD membrane, CL-E. RBC and reticulocyte counts were done monthly. RBC survival (51Cr T/2) was assayed in 18 patients before and after the end of the study. Oxidative status was determined in 10 patients by measuring plasma concentrations of malondyhaldeide-4-hydroxynonenal (MDA-4HNE), reactive oxygen molecular species (ROMs), and oxydized-LDL (oxLDL) as indices of oxidative stress, alpha-tocopherol and total thiols as single antioxidants, and TAS as a marker of total antioxidant plasma activity. RESULTS: Antioxidant treatment significantly reduced the high basal plasma concentrations of MDA4HNE and oxLDL, and significantly increased those of alpha-tocopherol, whereas TAS and thiols were unmodified. These changes lasted after the reduction of EPO. Anemia significantly improved with treatment, due to a significant increase in RBC survival. A close direct linear relationship was detected between plasma levels of vitamin E and hemoglobin. CONCLUSIONS: Adequate control of oxidative stress achieves better control of anemia in HD patients. Since several antioxidant systems are impaired in uremia, the combined use of the CL-E membrane and GSH seems to be the best antioxidant therapy so far, with significant saving of the rhEPO dose.

Effects of erythropoietin and vitamin E-modified membrane on plasma oxidative stress markers and anemia of hemodialyzed patients.

BACKGROUND: Oxidant stress has a pathogenic role in uremic anemia, possibly interfering with erythropoietin (EPO) function and red blood cell (RBC) survival. Therefore, it is expected that antioxidant therapy might exert a beneficial effect on these parameters. METHODS: To test this hypothesis, we investigated some oxidant stress indices, anemia levels, and RBC survival in 47 hemodialysis (HD) patients randomly assigned to three groups. Patients in groups A (n = l8) and B (n = 20) were on dialysis therapy using conventional cellulosic and synthetic membranes and were administered high and low doses of recombinant human EPO (rHuEPO), respectively. Patients in group C (n = 9) were dialyzed with vitamin E-modified membranes (CL-Es) and investigated in a two-step prospective study. In step Cl, patients were administered rHuEPO doses similar to those of group A. In step C2, rHuEPO doses were reduced to those of group B. As oxidant stress markers, we determined in plasma the susceptibility of lipids to undergo iron-catalyzed oxidation (reactive oxygen molecules [ROMs] test) and malondialdehyde-4-hydroxynonenal (MDA-4HNE), alpha-tocopherol (alpha-T), total thiol (-SH), and total antioxidant activity. RBC survival was measured using the chromium 51 T/2 technique in 22 patients. RESULTS: Results show that: (1) high rHuEPO doses (groups A and C1) were associated with decreased ROM production, low alpha-T levels, and slightly increased -SH levels compared with corresponding groups on low rHuEPO doses (groups B and C2); (2) treatment with CL-Es (group C) increased plasma alpha-T and decreased -SH levels; these data were associated with decreased indices of lipid peroxidation, particularly MDA-4HNE 1evels, only in patients administered low rHuEPO doses; (3) alpha-T concentration influenced RBC survival, which was remarkably decreased in HD patients; patients treated with CL-Es showed a better degree of anemia correction; and (4) alpha-T level correlated negatively with -SH level and seemed to be independent of the extent of peroxidation and oxidizability of plasma lipids. CONCLUSION: Both EPO and CL-E can influence plasma antioxidants and, to an extent, lipid peroxidation processes. However, this study shows that even in patients treated with low rHuEPO doses, RBC survival close to normal and sufficient correction of anemia are achieved only when appropriate alpha-T levels are reached.

Oxidative stress and cardiovascular disease in dialyzed patients.

BACKGROUND/AIM: Oxidative damage has been suggested to play a key role in accelerated atherosclerosis and to be involved in cardiovascular disease (CVD) of dialyzed patients who are at risk of increased oxidative stress. The purpose of the present study was to examine the relationship between the severity of CVD and some markers of oxidative stress and antioxidant activity in our hemodialyzed (HD) and peritoneal dialysis (PD) patients. METHODS: Plasma reactive oxygen metabolites, malondialdehyde and 4-hydroxynonenal (MDA-4HNE), thiols, alpha-tocopherol, and total antioxidant status (TAS) were measured in 55 HD and in 16 PD patients. CVD was considered as the result of variably combined cardiac, cerebral, and vascular pathologies which were scored and grouped in a single CVD index and analyzed with respect to the markers of the oxidative status. 16 normal subjects served as controls. RESULTS: All patients showed evidence of increased oxidative stress which was more severe in HD than in PD patients and which was exacerbated by HD. When cardiac, cerebral, and vascular diseases were analyzed separately, plasma MDA-4HNE and TAS were significantly higher in more severely affected HD patients, but not in PD patients. In HD patients the CVD index was directly correlated with both MDA-4HNE and TAS (r = 0.42, p < 0.01; r = 0.39, p < 0.01) and inversely correlated with alpha-tocopherol (r = -0.32, p < 0.05). MDA-4HNE and TAS were directly correlated in HD patients and inversely correlated in control subjects. CONCLUSIONS: Our data show that, in spite of increased antioxidant defense, there is a relationship between the degree of lipid peroxidation and the severity of CVD in HD patients. Moreover, these data underscore the utility of MDA-4HNE, alpha-tocopherol, and TAS in the evaluation of cardiovascular disease.