Oxidative stress and ferritin levels in haemodialysis patients.

BACKGROUND: Increased oxidative stress (OS) and inflammation are associated with atherosclerotic coronary artery disease in haemodialysis (HD) patients. Ferritin may have other effects in addition to its role in storing intracellular iron. This study was performed to determine any relationships between markers of OS, nutrition and inflammation in HD patients with normal and high ferritin levels. METHODS: Our cohort comprised 34 maintenance dialysis patients on erythropoietin therapy and 22 healthy controls. HD patients were divided into two groups: 17 with normal (<800 ng/ml) and 17 with high (>800 ng/ml) ferritin levels, and we measured lipid profile, albumin, highly sensitive C-reactive protein (hsCRP), anti-oxidant enzymes [whole blood glutathione peroxidase (Gpx), serum superoxide dismutase (SOD), paraoxonase, arylestherase (AE) and total anti-oxidant status (TAOC)], anti-oxidants (vitamin C) and lipid peroxidation products [red blood cell malondialdehyde (RBC MDA)]. RESULTS: Compared with controls, the HD patients had higher serum urea, blood pressure, triglyceride, hsCRP, RBC MDA, SOD and TAOC values and lower albumin, low-density lipoprotein cholesterol, apolipoprotein AI, paraoxonase, AE and whole blood Gpx activities. Serum vitamin C, uric acid, apolipoprotein B, total- and high-density lipoprotein cholesterol, apolipoprotein B MDA, and lymphocyte levels in the HD patients with normal and high ferritin levels were similar. The OS markers of HD patients did not differ, whether or not they received intravenous iron supplementation or had transferrin saturations < 50% or > or = 50%. CONCLUSION: HD patients are in a higher oxidative state, which results in the reduction of total anti-oxidant capacity and also have an increased inflammation status. We could not find a relationship between ferritin level and OS markers in HD patients receiving erythropoietin.     

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.     

Vitamin E-coated dialyzer and antioxidant defense parameters: three-month study

Atherosclerotic cardiovascular disease is the most frequent cause of death in patients with end-stage renal disease who have undergone dialysis treatment. Oxidative stress, increased lipid peroxidation, and impaired function of antioxidant systems may contribute to the accelerated development of atherosclerosis in chronic renal failure patients during renal replacement therapy. The aim of this study was to investigate the influence of a vitamin E-coated dialyzer on antioxidant defense parameters in hemodialysis (HD) patients. In 14 HD patients, hemodialysis was performed using a vitamin E-coated dialyzer (Terumo CL-E15NL; Terumo Corporation, Tokyo, Japan) during a 3-month study. In these patients, erythrocyte (ER) antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR) and catalase (CAT), plasma total antioxidant capacity (TAC), RBC glutathione (GSH), plasma malondialdehyde (MDA), plasma, and RBC vitamin E were investigated. Each parameter was measured at the beginning of the study, after the 1st, 2nd, and 3rd month of the study, and 10 weeks after the interruption of the use of vitamin E-coated dialyzer. All HD patients were treated by erythropoietin (EPO) and received vitamin C 50 mg/d, pyridoxine 20 mg/d, and folic acid 5 mg/wk during the entire study. The 3-month treatment with the vitamin E-coated dialyzer led to a significant decrease of plasma MDA level (from 2.85 +/- 0.44 to 2.25 +/- 0.37 micromol/L) and to an increase of plasma TAC, RBC, GSH, and the vitamin E levels both in plasma (from 25.9 +/- 2.8 to 33.6 +/- 3.8 micromol/L) and in the RBCs (from 6.7 +/- 0.8 to 7.4 +/- 0.7 micromol/L) by 30% and 10.5%, respectively. Ten-week interruption of the use of the vitamin E-coated dialyzer led to near initial values of MDA (2.90 +/- 0.28 micromol/L), plasma (28.6 +/- 3.5 micromol/L), and RBC (6.9 +/- 0.7 micromol/L) vitamin E and of other investigated parameters. Statistical analysis of results was performed by conventional methods and analysis of variance. The findings of the current study confirm the beneficial effect of the vitamin E-coated dialyzer against oxidative stress in HD patients.     

Antioxidant status of elderly chronic renal patients treated by continuous ambulatory peritoneal dialysis

BACKGROUND: An oxidative stress has been reported in patients with chronic renal failure (CRF) treated by haemodialysis. To our knowledge, only scant information is available concerning CRF patients treated by continuous ambulatory peritoneal dialysis (CAPD) with regard to their redox and nutritional status. METHODS: The oxidative stress and the biological nutritional status were evaluated in 20 elderly CRF patients treated by CAPD, compared with a control group of 30 elderly non-CRF patients. Plasma peroxidation products were assayed as thiobarbituric acid-reactive substances (TBARS), and two enzymatic antioxidant systems were determined: erythrocyte superoxide dismutase (SOD), glutathione peroxidase activity in plasma (P-GSH-Px) and in erythrocytes (E-GSH- Px). Selenium, vitamin E, beta-carotene and vitamin A were evaluated as plasma non-enzymatic antioxidants. Nutritional status and iron status were assessed by determining serum albumin, prealbumin, iron, ferritin and transferrin concentrations. RESULTS: Plasma TBARS concentration was high in both groups (CAPD: 1.37 +/- 0.06 mumol/l versus non-CRF: 1.41 +/- 0.06 mumol/l; P = NS), compared with usual values (0.60 to 1.20 mumol/l), on account of the patients' ages. SOD and E-GSH-Px activities were normal in both groups. A significant lowering in P-GSH-Px activity was observed only in CAPD patients (211 +/- 14 U/l, usual values: 480 to 650 U/l). Plasma selenium concentration, decreased in both groups, was significantly lower in CAPD than in non-CRF patients (P < 0.01). Plasma vitamin E, beta-carotene and vitamin A concentrations were significantly enhanced only in CAPD patients (P < 0.0001, P < 0.005 and P < 0.0001, respectively. Biological nutritional markers were similar in both groups and within usual values. CONCLUSIONS: This study demonstrated the existence of an oxidative stress in CAPD-treated elderly CRF patients, evidenced by a decrease in plasma selenium levels and in P-GSH-Px activity. However, plasma TBARS were not higher in CAPD patients than in age-matched non-CRF control subjects, probably on account on the patients' ages.      

Blood oxidative stress and lipoprotein oxidizability in haemodialysis patients: effect of the use of a vitamin E-coated dialysis membrane.

BACKGROUND: Oxidative stress has been shown in haemodialysis patients in relation with an increased production of free radicals due to membrane-induced complement and leukocyte activation. In order to minimize membrane bioincompatibility and thereby oxidative stress, more compatible filters have been perfected. Among them, a high-flux vitamin E-coated membrane (CL-EE) has been proposed recently. In vivo, little data is available on the consequences of the use of vitamin E-coated membranes. In the present study, the effects of a 3-month use of CL-EE dialysis membranes compared to conventional membranes have been evaluated in 12 haemodialysis patients on the blood oxidative stress status before and after the dialysis session. METHODS: We determined the lipid peroxidation status (plasma thiobarbituric acid-reactive substances) and antioxidant defence (erythrocyte Cu,Zn-superoxide dismutase and plasma and erythrocyte glutathione peroxidase activities, plasma vitamin E, beta-carotene, vitamin A and total antioxidant status). Also, we simultaneously determined the antioxidant content and the copper oxidizability of isolated low density- and high density-lipoproteins (LDLs and HDLs). RESULTS: The main consequence observed under these conditions was a marked enrichment of plasma with vitamin E, which was also significantly and selectively noted in HDLs (no changes in LDL vitamin E content), perhaps related to a specific storage capacity for vitamin E in HDLs of haemodialysis patients. The beta-carotene content of plasma, LDLs and HDLs was also higher after use of vitamin E-coated membranes than after use of high-flux biocompatible membranes. HDL copper oxidizability was reduced (as shown by an increased lag time) before dialysis after use of CL-EE membranes compared to conventional membranes, whereas LDL oxidizability remained unchanged. CONCLUSION: A 3-month use of vitamin E-coated membranes resulted in a significant increase in plasma and HDL vitamin E content, associated with a lower oxidizability of HDLs, which could be beneficial for haemodialysis patients.     

Vitamin E alleviates the oxidative stress of erythropoietin in uremic children on hemodialysis

The efficacy of combined therapy with recombinant human erythropoietin (rhEPO) and vitamin E versus rhEPO alone in the treatment of anemia was examined in children (n=10, aged 15.2±3.2 years) on chronic hemodialysis at the restart of rhEPO therapy after a 4-week interval. The results confirmed that rhEPO induced oxidative stress of the red blood cells as observed during the first rhEPO therapy. Vitamin E (15 mg/kg per day per os) was introduced after 2 weeks of rhEPO monotherapy, when the signs of acute oxidative stress appeared. The level of oxidized glutathione (GSSG) increased from 8.9±3.1 to 26.7±5.7 nmol/g hemoglobin (Hb) by that time. After 2 weeks of simultaneous vitamin E treatment, there was a significant difference in GSSG values compared with rhEPO monotherapy (10.1±3.9 vs. 56.7±15.8 nmol/g Hb, P<0.001). A considerable decrease was observed in the previously high ratio of GSSG/reduced glutathione (GSH), an indicator of oxidative stress, and the level of carboxyhemoglobin, indicating hemolysis. A significant increase in Hb and hematocrit (P<0.01) was achieved within 2 weeks of starting the combined therapy, while similar results occurred only at the 8th and 5th weeks without vitamin E. Antioxidant vitamin E supplementation improved the therapeutic effect of rhEPO in patients with chronic renal failure on hemodialysis. Received: 3 December 1998 / Revised: 20 April 1999 / Accepted: 20 April 1999     

Does long-term treatment of renal anaemia with recombinant erythropoietin influence oxidative stress in haemodialysed patients?

Background. Patients with end-stage renal failure undergoing haemodialysis (HD) are exposed to oxidative stress. Increased levels of malondialdehyde (MDA) were demonstrated in plasma of uraemic patients, indicating accelerated lipid peroxidation (LPO) as a consequence of multiple pathogenetic factors. The aim of our investigation was to examine the role of renal anaemia in oxidative stress in HD patients. Methods. MDA and 4-hydroxynonenal (HNE) were measured in three groups of patients undergoing HD: group I comprised eight patients with a blood haemoglobin (Hb) <10 g/dl (mean Hb=8.1±1.3 g/dl), and group II were eight patients with a Hb <10 g/dl (mean Hb=12.4±1.9 g/dl); none of these 16 patients had been treated with human recombinant erythropoietin (rHuEpo). Group III comprised 27 patients with a mean Hb of 10.5±1.6 g/dl after long-term rHuEpo treatment. Results. Mean plasma concentrations of both MDA and HNE were significantly higher (P<0.0001) in all 43 HD patients than in 20 healthy controls (MDA 2.85±0.25 vs 0.37± &mgr;M, HNE 0.32± vs 0.10±0.01 &mgr;M). Comprising the three groups, it was shown that HD patients with a Hb <10 g/dl had significantly higher plasma levels of LPO products (MDA 3.81±0.86 &mgr;M, HNE 0.45±0.07 &mgr;M) than HD patients with a Hb > 10 g/dl (MDA 2.77±0.58 &mgr;M, HNE 0.25±0.05 &mgr;M), and than HD patients treated with rHuEpo (MDA 2.50±0.12 &mgr;M, HNE 0.29±0.03 &mgr;M). Furthermore, an inverse correlation between plasma concentration of LPO products and haemoglobin levels was seen (r=0.62, P<0.0001). Conclusion. Radical generation in HD patients might be caused in part by renal anemia itself. Treatment with rHuEpo may decrease radical generation effectively in HD patients due to the increase in the number of red blood cells and blood haemoglobin concentration. Keywords: erythropoietin; haemodialysis; HNE; lipid peroxidation; MDA; renal anaemia      

Platelet lipid peroxidation in haemodialysis patients: effects of vitamin E supplementation

In haemodialysis patients, increased concentrations of malonyldialdehyde and decreased vitamin E content indicate lipid peroxidation in the platelets from oxidative damage. The same process has been described in red blood cells and in mononuclear cells in peripheral blood. However, platelet aggregation is within normal limits and does not change after treatment with vitamin E. On the other hand vitamin E supplementation reverts completely the biochemical abnormality of the platelets.     

Effects of vitamin supplementation on microcirculatory disturbance in hemodialysis patients without peripheral arterial disease

AIMS: Dysfunctional endothelium caused by oxidative stress is thought to play a role in pathogenesis of a variety of conditions including atherosclerosis. We investigated whether a microcirculatory disturbance in hemodialysis (HD) patients was associated with increased oxidative stress and endothelial injury. PATIENTS AND METHODS: Transcutaneous oxygen tension (TcPO2) on the dorsum of the foot at rest was measured as a marker of microcirculation in 33 patients undergoing HD without clinical manifestations of peripheral arterial disease and 20 healthy controls. Furthermore, in order to examine whether TcPO2 was affected by antioxidants, oral supplementation with a combination of vitamin C (200 mg daily) and vitamin E (600 mg daily) was administered for 6 months to 8 patients with microcirculatory disturbance (TcPO2 values of 50 mmHg or less). Serum biochemical parameters including vitamins were also measured. RESULTS: Mean TcPO2 value was significantly lower in HD patients than in control subjects (47.9 +/- 13.5 mmHg versus 62.4 +/- 11.9 mmHg, p < 0.001). After vitamin supplementation, TcPO2 values remarkably increased (40.6 +/- 10.0 mmHg versus 57.4 +/- 6.5 mmHg, p < 0.005). Serum vitamin C and vitamin E levels increased significantly as well, while serum levels of thrombomodulin, a marker of endothelial injury, and thiobarbituric acid reactants, a marker of lipid peroxidation, were significantly decreased in comparison with those before supplementation. CONCLUSIONS: Our results suggest that the microcirculatory disturbance in HD patients seems to be associated with endothelial damage caused by oxidative stress. Combined supplementation with vitamin C and vitamin E may be of clinical benefit in improving the cutaneous microcirculation by reducing oxidative stress.     

Vitamin E in renal therapeutic regimens

Administration of vitamin E in children with immunoglobulin A (IgA) nephropathy, focal segmental glomerulosclerosis (FSGS) and type I diabetes demonstrated potential towards ameliorating progression. Oral vitamin E therapy reduced endothelial dysfunction, lipid peroxidation and oxidative stress in patients with chronic kidney failure (CKF). Moreover, the use of vitamin E-bonded hemodialyzers reduced atherosclerotic changes, erythropoietin dosage and muscular cramps in patients on hemodialysis (HD). However, several controlled clinical trials failed to document beneficial effects on the study subjects’ cardiovascular and renal outcomes. A recent report of increased all-cause mortality in adult patients receiving high dose vitamin E therapy has caused considerable concern and debate. These issues regarding the efficacy and safety of vitamin E in renal therapeutic regimens will be reviewed in this article.     

Homocysteine and lipid peroxidation in haemodialysis: role of folinic acid and vitamin E.

BACKGROUND: Cardiovascular diseases are the leading cause of death in haemodialysis patients. Hyperhomocysteinaemia is an independent risk factor. Basic research has provided strong evidence that oxidation of low-density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis. Oxidative stress, lipid metabolism alterations, and hyperhomocysteinaemia observed in haemodialysis patients could induce increases in LDL oxidation. This study was designed to determine the effect of folinic acid on hyperhomocysteinaemia and to assess the antioxidant efficacy of folinic acid. The antioxidant effect of folinic acid was compared with that of vitamin E. METHODS: Sixteen stable patients (11 men, five women; mean age 54.3+/-6.32 years) on standard haemodialysis received 400 mg of vitamin E, orally, at the end of each haemodialysis session for 3 months. After a 1-month wash-out, they received 10 mg of folinic acid, intravenously, at the end of each haemodialysis session for an additional 3 months. Blood samples were drawn in the morning after an overnight fast and before dialysis. Plasma vitamin E was analysed by high-pressure liquid chromatography. Malondialdehyde (MDA) was determined using a fluorimetric method and plasma copper oxidized anti-LDL antibodies (Ab-LDLox) were measured with an ELISA method using native LDL and oxLDL as antigens. Plasma homocysteine was determined by an FPIA method. RESULTS: Folinic acid supplements significantly reduced hyperhomocysteinaemia (-44%), MDA concentrations (-40%), and IgG-LDLox titres (-13%). CONCLUSIONS: Treatment with folinic acid lowers plasma homocysteine levels and, like vitamin E, affords antioxidant protection, which prevents lipid peroxidation. This lowering of lipid peroxidation may reduce the risk of atherosclerosis and prevent or delay cardiovascular complications in HD patients.     

Effects of vitamin C infusion and vitamin E-coated membrane on hemodialysis-induced oxidative stress

Chronic hemodialysis (HD) patients manifest anemia and atherosclerosis with associated oxidative stress. We explored whether intravenous infusion of vitamin C (VC) and/or use of vitamin E (VE)-coated dialysis membrane could palliate HD-evoked oxidative stress. Eighty patients undergoing chronic HD were enrolled and randomly assigned into four groups: HD with intravenous VC (n=20), HD with VE-coated dialyzer (n=20), HD with both (n=20), and HD with neither (n=20). We evaluated oxidative stress in blood and plasma, erythrocyte methemoglobin/ferricyanide reductase (red blood cells (RBC)-MFR) activity, plasma methemoglobin, and pro-inflammatory cytokines in these patients. All patients showed marked increases (14-fold) in blood reactive oxygen species (ROS) after HD. The types of ROS were mostly hydrogen peroxide, and in lesser amounts, O2*- and HOCl. HD resulted in decreased plasma VC, total antioxidant status, and RBC-MFR activity and increased plasma and erythrocyte levels of phosphatidylcholine hydroperoxide (PCOOH) and methemoglobin. Intravenous VC significantly palliated HD-induced oxidative stress, plasma and RBC levels of PCOOH, and plasma methemoglobin levels and preserved RBC-MFR activity. The VE-coated dialyzer effectively prevented RBCs from oxidative stress, although it showed a partial effect on the reduction of total ROS activity in whole blood. In conclusion, intravenous VC plus a VE-coated dialyzer is effective in palliating HD-evoked oxidative stress, as indicated by hemolysis and lipid peroxidation, and by overexpression of proinflammation cytokines in HD patients. Using VE-coated dialyzer per se is, however, effective in reducing lipid peroxidation and oxidative damage to RBCs.     

Homocysteine and C-reactive protein levels in Haemodialysis patients

Background: Mild to moderatehyperhomocysteinemia is very common amongpatients undergoing haemodialysis. There issufficient evidence that hyperhomocysteinemiais an independent risk factor forcardiovascular and or atheromatous disease inend stage renal failure patients. Vitaminsupplementation such as vitamin B6, B12 orfolate has been proposed to correct thismetabolic disturbance and it is to be proved ifthis intervention benefit these patients, butthere is no agreement whether oral folatesupplementation is capable to normalizehomocysteine levels in end stage renal failurepatients.Methods: In 53 patients, undergoinghaemodialysis, homocysteine levels (Hcy),folate, vitamin B12, ferritin and C-reactiveprotein (CRP) were estimated before and afterdialysis, without folate supplementation.Thirty voluntary blood donors were used ascontrols to compare homocysteine levels. Afterfour weeks of oral folate supplementation(10 mg/24 hours) the levels of homocysteine,serum folate and intra-erythrocyte folate wereestimated again. Eighteen months later thesurvival rate of our patients was recorded andanalyzed in relation to Hcy and CRP levels.Results: The results showed thathaemodialysis patients exhibited, almost,fourfold higher homocysteine levels thancontrols (27.39 ± 11.54 vs 7.38 ± 3.5, t = –8.2, p = 0.000000). Folate levels, vitamin B12 and CRP increase significantly afterhaemodialysis where as homocysteine levelsdecrease (Hcy1 vs. Hcy2: z = 2.08, p = 0.03).Fourteen (14) patients suffered from coronaryheart disease (CHD) and they exhibited thehigher levels of homocysteine (Hcy1 vs. CHD: z =–3.4, p = 0.0006). All estimations performedrevealed a negative correlation betweenhomocysteine levels and plasma orintra-erythrocyte folate. No other variableexhibited any significant influence uponhomocysteine levels. After folatesupplementation homocysteine levels in thewhole number of patients were unchanged(Hcy(before) vs. Hcy(after): 27.39 ± 11.54vs. 26.95 ± 8.22, z = 0.3, p = 0.7, NS). Whenpatients with homocysteine levels higher than24 µmol/L were selected, a significantdecrease was observed (34.77 ± 9.32 vs.30.0 ± 8.05, z = 2.09, p = 0.02). Forty-twopatients were treated with erythropoietin fortheir anemia and we found a positivecorrelation between C-reactive protein levelsand rhu-Epo dose (CRP vs. Epo: r = 0.45,p = 0.002). Homocysteine levels did not exhibitany significant influence upon short-termsurvival (U = –0.37, p = 0.3, NS) where as CRPlevels exhibit a significant influence uponshort-term survival (U = 2.15, p = 0.005).Conclusions: Homocysteine levels inhaemodialysis patients are fourfold higher thanhealthy controls. Folate, vitamin B12 and CRPincrease significantly after dialysis. Patientswith coronary heart disease exhibit the highestlevels of homocysteine. The homocysteine levelsare inversely related with the folate levels.The exogenous folate supplementation increasethe serum folate levels but decreaseshomocysteine only in patients with higher thanmild hyperhomocysteinemia. Hcy doesn't exertany significant effect upon the short-termsurvival of the haemodialysis patients but CRPlevel is a god predictor of the short-termsurvival of these patients.     

Effects of large dose vitamin E supplementation on anemia in hemodialysis patients

In order to clarify the effect of vitamin E (alpha-tocopherol) on anemia and the osmotic fragility of red blood cells (RBC) plasma and RBC levels of vitamin E were measured in 30 regular dialysis patients before and after oral supplementation of vitamin E, 600 mg daily for 30 days. Plasma levels of vitamin E were in the normal range (10.67 +/- 0.85, 9.73 +/- 0.77 microgram/ml) but RBC levels in packed red cells were significantly lower than healthy controls (0.57 +/- 0.05, 0.45 +/- 0.07 microgram/ml). Oral supplementation of vitamin E increased both plasma (20.37 +/- 1.61 micrograms/ml) and RBC vitamin E (1.56 +/- 0.11 micrograms/ml) in packed red cells, while in unsupplemented patients, vitamin E levels remained unchanged. In patients receiving vitamin E, mean osmolarities at the beginning and end of hemolysis decreased from 102.8 +/- 0.9 to 98.9 +/- 0.7 and 72.1 +/- 1.1 to 67.4 +/- 0.8 mosm/l, respectively. In addition, the hematocrit increased from 26.1 +/- 1.0 to 28.1 +/- 1.2%. These changes are statistically significant (less than 0.05). In conclusion, the oral supplementation of vitamin E could be of clinical benefit in correcting anemia in regular dialysis patients by reducing the fragility of RBCs.     

Influence of oxidative stress and alpha tocopherol supplementation on urothelial cells of the urinary bladder in ovariectomised rats

The present study was designed to investigate whether vitamin E supplementation would influence the levels of oxidative stress and the damage to urothelial cell DNA in the bladders of castrated rats. A total of 30 rats of the Wistar breed were divided into 3 groups of 10 animals each. Group 1 underwent a sham procedure and was killed after 30 days; group 2 underwent bilateral oophorectomy and was killed after 30 days without receiving vitamin E supplementation and group 3 underwent bilateral oophorectomy and received vitamin E supplementation at a dose of 1,000 IU/kg once a week intra-muscularly for 30 days. Four weeks after the procedure, the rats were anesthetised and their bladders were rapidly removed, frozen and stored at −70°C for Comet assaying, which was carried out on lymphocytes and vesicular urothelium cells. The 8-isoprostane concentration in plasma was also determined to confirm the presence of oxidative stress. The 8-isoprostane levels found were higher in oophorectomised rats that had not received vitamin E supplementation than in the sham group and the oophorectomised group with vitamin replacement. Tail moment analysis on the urothelial cells demonstrated that the oophorectomised group presented DNA damage that was statistically significant in comparison with the other groups. On the basis of the above data, vitamin E decreased the effects of oophorectomy on lipid peroxidation and avoided the DNA damage observed in urothelial cells.     

Haemolysis in haemodialysis patients: evidence for impaired defence mechanisms against oxidative stress.

BACKGROUND: Uraemic patients have a decreased ability to withstand oxidative stress. It is postulated that their antioxidant capacity is reduced, yet the mechanism remains unclear. Recently 33 haemodialysis (HD) patients were exposed to chloramine contamination in the water supply. This led to haemolysis in 24 patients, while nine were unaffected. In the former group haemoglobin decreased from 11.7+/-1.1 to 8.5+/- 1.4 g/dl (P<0.0001) and returned to 11.4+/-0.9 g/dl (P<0.0001) following recovery. During haemolysis, haptoglobin was 38.4+/-10.6 vs 138.1+/-8.3 ng/dl (P<0.0001) following recovery. METHODS: To explore the factors affecting the severity of haemolysis we studied extracellular and intracellular anti-oxidant defence mechanisms 3 months after recovery. In 29 patients and 20 controls we determined plasma glutathione (GSH), and the erythrocyte enzymes glutathione peroxidase (GSH-Px), glutathione reductase (GSH-Rx), and superoxide dismutase (SOD). Serum malondialdehyde (MDA) was measured as a marker of oxidative stress. RESULTS: Plasma GSH was lower in patients as compared to controls (5.49+/-0.26 vs 7.4+/-0.5 micromol/l, P<0.005). There was an inverse correlation between GSH and the degree of haemolysis (r=-0.42, P<0.02). Patients had higher GSH-Rx (4.64+/-0.15 vs 3.97+/-0.12 U/gHb, P<0.02), lower GSH-Px (29. 7+/-1.85 vs 35.5+/-1.62 U/gHb, P<0.001), and similar SOD (0.63+/-0. 02 vs 0.51+/-0.02 U/mgHb) as compared to controls. There was no correlation between the enzyme levels and the degree of haemolysis. MDA was higher in patients (2.37+/-0.07 vs 0.97+/-0.1 nmol/ml, P<0. 0001). There was a correlation between MDA and the years patients were on HD (r=0.43, P<0.02). CONCLUSIONS: These data indicate that HD patients have an impaired anti-oxidant response, which may be attributed in part, to plasma GSH deficiency. Patients with the lowest plasma GSH levels are more susceptible to oxidative stress and consequent haemolysis.     

Renal tubular cell damage and oxidative stress in renal stone patients and the effect of potassium citrate treatment

Our objective was to evaluate the oxidative stress and renal tubular cell damage in patients who have renal stones compared to normal subjects. The patients were re-evaluated after 1-months supplementation with potassium citrate. We recruited 30 patients (11 males and 19 females) diagnosed with kidney stones and scheduled for surgical stone removal the following month, and 30 healthy non-stone formers (14 males and 16 females). Two 24-h urine samples and one heparinized blood sample were collected from each subject. Plasma was separated from the erythrocytes and assayed for creatinine, potassium, sodium, calcium, magnesium, phosphate, malondialdehyde (MDA, a lipid peroxidation product) (P-MDA), protein thiol as an indicator of protein oxidation, and vitamin E. Erythrocytes were analysed for MDA (E-MDA), reduced glutathione (GSH) and cellular glutathione peroxidase (cGPx) activity. The urine was analyzed for pH, creatinine, potassium, sodium, calcium, magnesium, phosphate, oxalate, citrate, MDA (U-MDA), total protein (U-protein) and N-acetyl--glucosaminidase (NAG) activity. For the stone patients, urine and blood samples were re-evaluated after supplementation with potassium citrate (60 mEq/day) for 1 month. Renal stone patients had higher plasma creatinine and lower plasma potassium, urinary pH, potassium, magnesium, phosphate and citrate than the controls. The patients had higher P-MDA, E-MDA, U-MDA, U-protein and NAG activity, but lower GSH, cGPx activity, protein thiol and vitamin E, when compared with controls. After potassium citrate supplementation, P-MDA and E-MDA decreased while plasma vitamin E, urinary NAG activity and citrate increased. Renal stone disease is associated with high oxidative stress and damage to renal tubular cells. These abnormalities are coincident with an increase in blood lipid peroxidation products and a decrease in antioxidant status. Although supplementation with potassium citrate improved urinary citrate levels and oxidative stress, it neither reduced urinary lipid peroxidation products nor remedied the damage to renal tubular cells, probably due to the existence of kidney stones.     

Evidence of red blood cell membrane lipid peroxidation in haemodialysis patients

Some metabolic alterations of the pentose-phosphate shunt can increase susceptibility to red blood cell (RBC) lipid peroxidation in uraemic patients on maintenance haemodialysis. We investigated this phenomenon in 19 uraemic patients undergoing chronic haemodialysis by determining RBC malonyldialdehyde (MDA), a secondary product of lipid peroxidation and plasma and RBC tocopherols, which are powerful antioxidants. Evidence of RBC membrane lipid peroxidation was demonstrated by an increase of RBC MDA. RBC tocopherols were significantly decreased because of enhanced antioxidant activity. No significant variations of these parameters were found before and after dialysis.     

Effect of vitamin E therapy on oxidative stress and erythrocyte osmotic fragility in patients on peritoneal dialysis and hemodialysis

BACKGROUND: Several medications have been tested with the aim of decreasing oxidative stress and erythrocyte osmotic fragility in patients on dialysis. The aim of the present study was to assess the influence of vitamin E therapy on oxidative stress and erythrocyte osmotic fragility in patients on hemodialysis (HD) and peritoneal dialysis (PD). METHODS: This was a placebo-controlled study. The study was performed on 34 HD patients, 13 PD patients and 22 healthy volunteers with a mean age of 45.57 +/- 8.54 years. HD patients were divided into 2 groups: treatment (n=19) and control (n=15). Vitamin E was administered, 300 mg/day, to the HD treatment group and PD patients for 20 weeks. Lipid peroxidation, antioxidant condition and erythrocyte osmotic fragility (EOF) were examined before and after treatment. RESULTS: Before the treatment, the levels of EOF (p<0.001) and malondialdehyde (MDA) (p<0.001) were significantly lower, and erythrocyte superoxide dismutase (SOD) (p=0.001) and vitamin E levels (p<0.001) were significantly higher in the healthy group than PD and HD groups. Serum vitamin E increased from 0.93 +/- 0.16 to 1.09 +/- 0.14 mg/dL (p=0.001), EOF decreased from 0.49% +/- 0.03% to 0.42% +/- 0.04% NaCl (p<0.001), and plasma MDA values decreased from 2.77 +/- 0.87 to 2.20 +/- 0.767 nmol/mL (p=0.018) in the HD treatment group after vitamin E treatment. Levels of EOF decreased from 0.51% +/- 0.09% to 0.43% +/- 0.03% NaCl in the PD treatment group after vitamin E treatment (p=0.021). CONCLUSION: Vitamin E therapy is effective in decreasing the levels of EOF in patients on HD and PD, and it is also effective in decreasing lipid peroxidation in patients on HD.     

Vitamin E suppresses oxidative stress and glomerulosclerosis in rat remnant kidney

 Previous studies have shown that reduction of renal mass in the rat remnant kidney model induces overproduction of transforming growth factor β1 (TGFβ1). We investigated whether an antioxidant, vitamin E, administered before the renal mass reduction, could prevent oxidative stress, reduce the overproduction of TGFβ1, and mitigate against the subsequent glomerulosclerosis. Our results revealed that the oxidative stress, as measured by the change in plasma malondialdehyde, is significantly reduced by prior vitamin E dietary supplementation. Finally, our data show that dietary vitamin E supplementation ameliorates the rise in TGFβ1 secondary to renal mass reduction and inhibits the glomerular sclerosis of the remnant kidney over the time course of this experiment. Received: 27 January 1998 / Revised: 7 May 1998 / Accepted: 8 May 1998