Intravenous ascorbic acid as an adjuvant therapy for recombinant erythropoietin in hemodialysis patients with hyperferritinemia

Nitric oxide, oxidative stress, and progression of chronic renal failure

Cellular injury or organ dysfunction from oxidative stress occurs when reactive oxygen species (ROS) accumulate in excess of the host defense mechanisms. The deleterious effect of ROS occurs from 2 principal actions. First, ROS can inactivate mitochondrial enzymes, damage DNA, or lead to apoptosis or cellular hypertrophy. Second, nitric oxide (NO), which is a principal endothelial-derived relaxing factor, reacts with superoxide anion (O2-) to yield peroxynitrite (ONOO-), which is a powerful oxidant and nitrosating agent. The inactivation of NO by O2- creates NO deficiency. Oxidative stress can promote the production of vasoconstrictor molecules and primary salt retention by the kidney. Several hypertensive animal models showed increased activity of nicotine adenine dinucleotide phosphate (NADPH) oxidase, which is the chief source of O2- in the vessel wall and kidneys. NO regulates renal blood flow, tubuloglomerular feedback (TGF), and pressure natriuresis. Animal models of NO deficiency develop hypertension, proteinuria, and glomerulosclerosis. Evidence is presented that chronic renal failure (CRF) is a state of NO deficiency secondary to decreased kidney NO production and/or increased bioinactivation of NO by O2-. Patients with CRF show decreased endothelium-dependent vasodilatation to acetylcholine, have increased markers of oxidative stress, and diminished antioxidant activity. Therapy for oxidative stress has focused on antioxidants and agents that modify the renin-angiotensin system. The effects of such treatments are more compelling in animal models than in human studies.

Special Article: Improving Outcomes in CKD and ESRD Patients: Carrying the Torch from Training to Practice

Practicing nephrologists are spending more time caring for end-stage renal disease (ESRD) and chronic kidney disease (CKD) patients. Despite this focus, and considerable advances in the understanding of those aspects of care that impact on clinical outcomes, morbidity, mortality, and quality of life for these patients has not improved substantially over the past decade. One of the possible explanations for this lack of progress is the structure of current nephrology training programs, where ESRD and CKD patient care is not emphasized. To address this issue, we developed a short preceptorship for second-year nephrology fellows, including didactic lectures and workshops. Of 67 participating fellows, 50% were from programs offering 3 or fewer months of exposure to outpatient hemodialysis, and 25% reported no exposure to peritoneal dialysis. Of more concern, 25% reported no "official rounds" with an attending nephrologist on dialysis patients. If nephrologists are to take their appropriate place as leaders of the care delivery team, nephrology fellowships must be restructured with appropriate emphasis placed on the comprehensive care of ESRD and CKD patients.

Protective effect of vitamin C on 8-hydroxy-2′-deoxyguanosine level in peripheral blood lymphocytes of chronic hemodialysis patients

BACKGROUND

This study focused on the effect of vitamin C on the 8-hydroxy-2'-deoxyguanosine (8-OHdG) level of cellular DNA, as well as 8-oxoguanine-DNA glycosylase 1 (hOGG1) and human MutT homologue (hMTH1) gene expression in peripheral blood lymphocytes of chronic hemodialysis patients.

METHODS

Sixty chronic hemodialysis patients (35 men and 25 women) were recruited to participate in a randomized, placebo-controlled study. Treatment order is block-randomized with intravenous sodium ascorbate (vitamin C, 300 mg) or placebo (0.9% saline), administered postdialysis three times a week. We evaluated 8-OHdG level, intracellular reactive oxygen species (ROS) production, and gene expression of hOGG1 and hMTH1 in peripheral blood lymphocytes by using high-performance liquid chromatography (HPLC) electrochemical detection method, flow cytometric analysis, and reverse transcription-polymerase chain reaction (RT-PCR), respectively.

RESULTS

A total of 51 patients completed the study (26 in placebo group and 25 in vitamin C group). Mean 8-OHdG levels significantly decreased in total subjects following 8 weeks of vitamin C supplementation (22.9 vs. 18.8/10(6) dG, P < 0.01). The decrease in 8-OHdG levels after vitamin C supplementation was also noted in the patients with ferritin <500 or > or =500 microg/L and transferrin saturation (TSAT) <50 or > or =50% (P < 0.05). But 8-OHdG levels had no significant changes in total patients or in the four subgroups of patients treated with placebo as compared to their baselines. Intracellular ROS production by lymphocytes from the four subgroups of patients, either spontaneous (P < 0.05) or phorbol-12-myristate-13-acetate (PMA)-stimulated (P < 0.001), was significantly reduced after 8 weeks vitamin C supplementation. Steady-state hOGG1 mRNA levels were significantly up-regulated at 24 hours after vitamin C administration (P < 0.05), but hMTH1 mRNA levels were not. The changes in the spontaneous and PMA-stimulated ROS production, and an up-regulation of hOGG1 mRNA expression were not observed in patients treated with placebo as compared to their baselines.

CONCLUSION

Vitamin C supplementation in chronic hemodialysis patients can reduce the lymphocyte 8-OHdG levels and intracellular ROS production, as well as up-regulate hOGG1 gene expression for repair. There is no compelling evidence for an in vivo pro-oxidant effect of vitamin C on lymphocyte DNA base oxidation, even in the status of increased iron stores.

Iron supplementation in the intensive care unit: when, how much, and by what route?

Derangements of iron metabolism may be present in critically ill patients who develop anemia during a stay in the intensive care unit. Iron supplementation may be appropriate, especially if an underlying nutritional disorder is present. It may be even more critical to replace iron when erythropoietin therapy is used because of the consumption of iron stores that occurs during heme synthesis. Iron therapy is not without risks, and controversy persists regarding the potential for iron overload and infections. Clinical trials that define the optimal dose, route, and timing of iron administration in critically ill patients are lacking. However, studies of iron supplementation in chronic kidney disease, pregnancy, and anemia of prematurity may provide some guidance about approaches to treatment. Clinical evidence and limitations that can assist clinicians in managing iron therapy in the intensive care unit are presented.

RENAL RESEARCH INSTITUTE SYMPOSIUM: Efforts to Determine the Role of Oxidant Stress in Dialysis Outcomes

The role of elevated markers of oxidant stress needs to be established in longitudinal studies. Oxidant stress markers such as malonaldehyde (MDA), isoprostanes, and breath hydrocarbons warrant rigorous application to outcomes, if they are to be used as clinical parameters. For example, investigations of C-reactive protein (CRP), parathyroid hormone (PTH), and several other clinical indicators have shown that these markers can be used to predict outcomes such as morbidity and mortality. Long-term followup is needed for intervention studies with antioxidants, since effects with short-term studies may be focused on critically-ill individuals where intervention would not be expected to be effective. Oxidant stress studies in this population especially need a long-term approach to test the hypothesis that antioxidant intervention is beneficial.

Effect of hemodialysis on the antioxidative properties of serum

In patients with chronic renal failure undergoing regular hemodialysis (HD), oxidative stress is involved in the development of dialysis-related pathologies. The aim of the study was to measure the effect of HD treatment on the general antioxidative status of serum with special consideration of the specific oxidizability of lipids and proteins. Indicators for the oxidative/antioxidative status of plasma were monitored at the beginning and at the end of a dialysis session on the arterial and venous side of the dialyzer. A decrease in the antioxidant status was accompanied by an increased oxidizability of proteins as well as lipids during HD treatment. During the first passage of the dialyzer, the lag time of lipid oxidation decreased from 114.0+/-19.8 to 81.5+/-18.9 min, the lag time of protein oxidation decreased from 105.0+/-24.6 to 72.9+/-21.3 min and the total antioxidative status decreased from 518+/-24 to 252+/-124 microM trolox equivalents. The carbonyl content of serum proteins was high in patients with end stage renal disease (ESRD) (3.9+/-1.1 vs. 0.9+/-0.1 nmol/mg in controls) but did not change significantly during dialysis procedure. Our data demonstrate that the susceptibility of serum lipids and proteins to oxidative modification is severely increased by HD treatment.

Effect of ascorbic acid administration in hemodialysis patients on in vitro oxidative stress parameters: influence of serum ferritin levels

BACKGROUND

Ascorbic acid supplementation has been recommended to circumvent resistance to erythropoietin, which sometimes occurs in iron-overloaded uremic patients. In considering the pro-oxidant effect of ascorbic acid, the authors hypothesize that adjuvant therapy with larger doses of ascorbic acid in hemodialysis patients with iron overload may raise the risk of increasing free radical generation. The oxidative stress of intravenous ascorbic acid supplementation in hemodialysis patients was evaluated in this study.

METHODS

Six healthy subjects and 29 hemodialysis patients were enrolled. Chemical scavenging activity of various compounds was measured by in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Free radical generation was determined in vitro by lucigenin-enhanced chemiluminescence (LucCL) assay on blood samples. Blood biochemistries were also measured simultaneously in hemodialysis patients 1 minute before and 5 minutes later in the presence or absence of intravenous injection of 300 mg ascorbic acid.

RESULTS

Ascorbic acid presented a strong antioxidant effect in DPPH chemical reaction. On the contrary, it exerted pro-oxidant effect when mixed with plasma or whole blood of healthy subjects and hemodialysis patients. The pro-oxidant effect of ascorbic acid detected by LucCL was attenuated by various iron chelators and superoxide dismutase. In hemodialysis patients, the changes of LucCL intensity were significantly higher in the ascorbic acid-treated group than those in the control group (1261.0 +/- 401.9 v 77.4 +/- 62.5 relative light unit [RLU]; P < 0.05). Adjuvant ascorbic acid therapy resulted in significantly higher LucCL intensity in hemodialysis patients with ferritin > or =600 ng/mL (1,348.2 pmol/L) than those with ferritin less than 600 ng/mL (2,296.0 +/- 763.8 v 414.3 +/- 88.0 RLU; P<0.05). The changes of LucCL intensity were positively correlated with serum ferritin level (R2=0.8673; P<0.05). However, there was no significant correlation between the responses of LucCL intensity to ascorbic acid administration and transferrin saturation (R2=0.195; P=0.0665).

CONCLUSION

Persons with excess ascorbic acid supplement in the blood or plasma generate iron-chelator-suppressible chemiluminescents suggestive of free radical formation. Whether the findings occur in vivo or that the free radicals generated in vitro lead to toxicity in patients is not known from this study. These results suggest that either lower parenteral dose or lower infusion rate of ascorbic acid may be more appropriate for adjuvant therapy in iron-overloaded uremic patients.

Randomized, crossover study of the effect of vitamin C on EPO response in hemodialysis patients

BACKGROUND

Vitamin C has been reported to be an effective adjuvant agent in the treatment of anemia in iron-overloaded hemodialysis patients. We aim to evaluate its effect on erythropoietin (EPO) response in a prospective, randomized, double-blind, crossover study.

METHODS

Sixty-three patients were randomly divided into two groups. Group 1 was treated with intravenous vitamin C, 500 mg, three times a week, and group 2, with placebo for 6 months. During the second 6-month period, group 1 was treated with placebo, and group 2, with the same dose of vitamin C. Thirty patients in group 1 and 28 patients in group 2 completed the study. Hemoglobin levels, weekly EPO dose, and ratio of EPO to hemoglobin as an index of EPO need were determined at both baseline and the end of the two periods, together with other parameters known to be associated with EPO response.

RESULTS

Twenty patients in group 1 (66.7%) and 18 patients in group 2 (64.3%) were responsive to vitamin C. In both groups, vitamin C resulted in a significant increase in hemoglobin levels (P < 0.0001 for both) and a significant decrease in EPO-hemoglobin ratio (P < 0.0001, P = 0.019). Transferrin saturation also increased with vitamin C treatment in both groups (P = 0.009, P = 0.005). All these parameters remained stable with placebo in both groups. Other parameters did not change throughout the study.

CONCLUSION

Vitamin C can be used as an effective adjuvant therapy to EPO in hemodialysis patients. Further studies are needed to determine possible predictors of hematologic response to vitamin C.

Low dose intravenous ascorbic acid for erythropoietin-hyporesponsive anemia in diabetic hemodialysis patients with iron overload

BACKGROUND

Recent report demonstrates that inadequate iron mobilization and defective iron utilization may cause recombinant erythropoieitin (rEPO) hyporesponsiveness in hemodialysis (HD) patients with iron overload. The effect of intravenous ascorbic acid (IVAA) in HD patients selected on the basis of iron overload and EPO resistance also has been proven. However, it is uncertain whether IVAA still works in diabetic ESRD patients with hyperferritinemia. Therefore, the aim of this study focusing on diabetic ESRD patients was to analyze the potential effect of low dose IVAA on improvement of anemia and erythropoiesis-related parameters when compared with control period.

PATIENTS AND METHOD

This study consisted of 22 chronic hemodialysis patients with type II diabetes in a single dialysis unit. In studies of this type, all eligible patients are followed up, but the primary comparison is still between different sequentially treatment including control period and post-IVAA period in same patients. IVAA patients received ascorbic acid, 100 mg each administered intravenously three times per week for eight weeks of treatment and four months of post-treatment follow-up.

RESULTS

The demographic characteristics of 22 diabetic uremic patients show that mean age is 63.6 +/- 10.2 years old. The ratio of sex (M/F) = 10/12. Mean duration of HD is 46.7 +/- 33.2 months. As for the urea kinetic study between these two periods including KT/V, nPCR, and URR, there is no significantly different. As for anemia-related parameters, Hb and Hct increased significantly in post-IVAA period after 3 months compared with control period, while MCV did not increase significantly. Serum ferritin significantly decreased at study completion. The same situation is for iron. As for TS, it significantly increased at one month and further markedly increased at subsequent three months.

CONCLUSION

This study has demonstrated that short-term low dose IVAA therapy can facilitate iron release from reticuloendothelial system but also increase iron utilization in diabetic hemodialysis patients with iron overload. Therefore, IVAA is a potential adjuvant therapy to treat erythropoeitin-hyporesponsive anemia in iron-overloaded patients.

Past, present and future of erythropoietin use in the elderly

More than a decade has passed since the first patient with end-stage renal failure was treated with erythropoietin (EPO) and more than 85% of patients now receive this therapy. In the year 2002 more than 60% of dialysis patients will be elderly, and the treatment of anemia will be more complex due to the aditional causes: folate, iron and vitamin deficiency in this population. Correction of anemia with EPO brings about partial regression of left ventricular hypertrophy and some data suggest that such treatment reduces cardiovascular mortality in patients without advance cardiac disease. Normalization of hematocrit with EPO increases oxygen supply to the brain tissue with improvement in brain function. The improvement in the ability to recognize, discriminate and hold stimuli in memory for difficult tasks is particularly important for elderly people. No differences have been noted in the incidence of clotting of vascular access in patients treated with EPO compared with hemodialysis patients not so treated. Also no one has demostrated that treatment with EPO accelerates renal decline in patients with progressive renal insufficiency. In elderly people with anemia secondary to advanced renal failure, EPO therapy improves physical, cognitive and sexual function, and health related quality of life.

Oral use of iron with vitamin C in hemodialyzed patients

OBJECTIVE

To investigate if oral use of Sorbifer Durules (EGIS Pharmaceutical Ltd, Budapest, Hungary) (1 tablet/d) is adequate for the maintenance of serum iron and vitamin C in normal range during recombinant human erythropoietin treatment in hemodialyzed patients. One tablet of Sorbifer Durules contains 100 mg of Fe(2+) and 60 mg of vitamin C.

DESIGN

Short-term, open-label clinical trial.

SETTING

Hemodialysis units.

PATIENTS

Twenty-four adult patients with end-stage renal disease on hemodialysis.

INTERVENTION

Four-week treatment period of Sorbifer Durules, preceded and followed by iron and vitamin C washout periods.

MAIN OUTCOME MEASURE

Fasting predialysis serum samples were collected on days 0, 28, 56, and 84 to determine hematocrit, blood hemoglobin, serum iron, total iron-binding capacity, transferrin saturation, ferritin, vitamin C, and plasma oxalate.

RESULTS

Four-week treatment in hemodialyzed patients by Sorbifer Durules led to significant increase of hematocrit, blood hemoglobin, serum iron and vitamin C. This treatment did not influence the level of plasma oxalate.

CONCLUSION

Oral dose of one tablet of Sorbifer Durules per day is adequate for the maintenance of serum iron in normal range during recombinant human erythropoietin treatment in hemodialyzed patients. This treatment simultaneously prevented the development of serum vitamin C deficiency and did not lead to further increase of plasma oxalate in these patients.

Intravenous ascorbic acid administration for erythropoietin-hyporesponsive anemia in iron loaded hemodialysis patients

Intravenous ascorbic acid administration (IVAA) could override recombinant human erythropoietin (rHuEPO) resistance in hemodialysis patients with iron overload. We investigated the hematopoietic response to IVAA in iron-overloaded hemodialysis patients. We included 36 patients whose ferritin levels were higher than 500 microg/L and who needed more than 100 U/kg/week of rHuEPO. The study included an initial phase (500 mg IVAA twice weekly was administered to all of the patients for 8 weeks) and a maintenance phase (patient groups were formed; Group 1 received IVAA 500 mg/week for 8 weeks and Group 2 received no therapy). We observed a significant increase in hematocrit and transferrin saturation and a decrease in the percentage of hypochromic red cells and ferritin levels at the end of the initial phase. The total weekly-required rHuEpo dose and rHuEpo/hemoglobin also fell significantly after the initial phase. The response remained stable in patient groups during the maintenance phase. In 6 nonresponders, the hypochromic red cells were <10%. In conclusion, IVAA effectively overrides rHuEPO resistance in iron-overloaded hemodialysis patients.

Effect of vitamin C on plasma total antioxidant status in patients with paraquat intoxication

This study was conducted to evaluate whether vitamin C (VC) was associated with total antioxidant status (TAS) in human plasma and to determine the usefulness of VC on TAS in the treatment of patients with paraquat poisoning. VC and TAS were measured in 56 healthy subjects. Then, various concentrations (1-100 mg/dl) of VC in pooled plasma from 10 volunteers were constructed in vitro and TAS was measured. The VC and TAS were measured in vivo at 0.5, 1, 2, 3, 5, 7, 9, and 11 h after injection of VC (50 mg/kg) in seven volunteers and pharmacokinetic data were calculated. Finally, various amounts of VC (100, 500, 1000, 3000 mg/day, and 3000 mg/8 h) were given to 10 paraquat-poisoned patients for 5 consecutive days, and blood was taken for TAS 1 h after each injection. The means (SD) of VC and TAS in healthy subjects were 2.22 (0.16) mmol/l and 0.48 (0.10) mg/dl, respectively. Positive correlation between VC and TAS was observed in both in vitro and in healthy volunteers. The pharmacokinetic results in vivo were as follows: means (SD) of distribution volume, area under curve, plasma clearance, half life, C(max), and T(max) were 32.0 (4.4) l, 36.4 (11.3) mg h/dl, 2.13 (1.36) l/h, 10.2 (7.8) h, 17.1 (7.1) mg/dl, and 0.64 (0.24) h, respectively. Estimated loading and maintenance doses of VC were 2278 mg and 146 mg/h, respectively. The means of TAS were increased over 5 consecutive days as 2.26, 2.76, 2.81, 3.18, and 3.58 mmol/l in paraquat patients. All patients were recovered within mean (SD) 21.2 (5.4) admission days. Our data suggested that VC was a significant antioxidant as TAS in human plasma and that increased TAS by high doses of VC could be useful as a free radical scavenger for paraquat poisoned patients.

Effect of human OGG1 1245C-->G gene polymorphism on 8-hydroxy-2'-deoxyguanosine levels of leukocyte DNA among patients undergoing chronic hemodialysis

The effects of the human OGG1 gene (hOGG1) 1245C-->G polymorphism on the 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents of peripheral leukocyte DNA were investigated among chronic hemodialysis patients. First, the hOGG1 1245C-->G transversion was assessed, by using a PCR-restriction fragment length polymorphism method, among 210 hemodialysis patients and 156 healthy individuals. Second, the 8-OHdG contents in leukocyte DNA were measured, by using an HPLC-electrochemical detection method, for 112 hemodialysis patients and 112 age-, gender-, and genotype-matched healthy control subjects. The three genotypes (as dummy variables) and age, gender, dialysis duration, dialyzer membrane type, blood antioxidant levels, and iron parameters were used as independent variables and the natural logarithm of the leukocyte 8-OHdG concentration was used as a dependent variable in a forward, stepwise, multiple-regression model. The results demonstrated that the allelic frequency of hOGG1 1245G was 64.1% among 210 hemodialysis patients and 62.2% in the whole control population. The genotypic frequencies (CC/CG/GG ratio, 10%/51.9%/38.1%) for the hemodialysis patients did not differ significantly from those (16.7%/42.3%/41.0%) for the control subjects (P > 0.05, chi(2) test). The mean leukocyte 8-OHdG levels for the patients were significantly higher than those for the healthy control subjects (P < 0.001). Leukocyte 8-OHdG levels were further increased among patients with the 1245GG genotype, compared with patients with the 1245CG or CC genotype (P < 0.001, ANOVA), but levels were similar among healthy control subjects irrespective of the hOGG1 gene polymorphism. It was also observed that patients who underwent dialysis with cellulose membranes exhibited significantly higher leukocyte 8-OHdG levels than did patients who underwent dialysis with polymethylmethacrylate, polysulfone, or vitamin E-bonded membranes (P < 0.001, ANOVA). The multivariate regression analysis revealed that hOGG1 1245C-->G polymorphism and dialysis membrane type were the two independent predictors of 8-OHdG contents in leukocyte DNA from hemodialysis patients. This study demonstrated that the extent of oxidative DNA damage among chronic hemodialysis patients not only is influenced by overproduction of reactive oxygen species resulting from leukocyte contacts with complement-activating membranes and by impaired antioxidant defense mechanisms but also is genetically determined.

Oxidative stress and haemodialysis: role of inflammation and duration of dialysis treatment

BACKGROUND

Oxidative stress has long been demonstrated in haemodialysis patients. However, the factors influencing their oxidative status have not been characterized extensively in these patients. Therefore, the present study was designed to investigate the influence of a large number of factors known to be associated with oxidative stress.

METHODS

In the present cross-sectional study, we determined the plasma levels of lipid and protein oxidation markers in 31 non-smoking haemodialysis patients and 18 non-smoking healthy subjects, together with various components of the antioxidant system at the plasma and erythrocyte level.

RESULTS

No influence of age, diabetes or iron overload on oxidative markers and plasma and erythrocyte antioxidant systems was detected in these haemodialysis patients. The lack of an association between iron overload and oxidative status may be related to the lower level of plasma ascorbate in haemodialysis patients, since ascorbate favours the generation of free iron from ferritin-bound iron. Interestingly, plasma C reactive protein (CRP) levels measured by highly sensitive CRP assay were correlated positively with plasma levels of thiobarbituric acid reactive substances (r=0.38, P<0.04) and negatively with plasma alpha-tocopherol levels (r=-0.46, P<0.01). Moreover, significant inverse correlations were observed between duration of dialysis treatment and plasma levels of alpha-tocopherol (r=-0.49, P<0.02) and ubiquinol (r=-0.40, P<0.05).

CONCLUSIONS

Our results suggest that inflammatory status and duration of dialysis treatment are the most important factors relating to oxidative stress in haemodialysis patients.

Diagnosis and management of iron deficiency in chronic dialysis patients

Tests have become available that not only give an index of iron stores and availability but also provide an integrated assessment of the efficacy of its utilization. This has allowed the revision of previously accepted criteria of iron deficiency as well as the most appropriate strategies for iron administration. By optimizing the response to erythropoietin, target haemoglobin levels may be reached with smaller doses, resulting in substantial savings.

Effect of vitamin E-bonded membrane on the 8-hydroxy 2'-deoxyguanosine level in leukocyte DNA of hemodialysis patients

BACKGROUND

8-Hydroxy 2'-deoxyguanosine (8-OHdG) of leukocyte DNA has been identified as a surrogate marker of oxidative stress in chronic hemodialysis (HD) patients. In this study, we focused on the determinants of the 8-OHdG level in leukocyte DNA of HD patients. We further investigated the influence of vitamin E-modified, regenerated cellulose (CL-E) membrane on the oxidative DNA damage, intracellular reactive oxygen species (ROS) production of granulocytes, and plasma alpha-tocopherol concentration.

METHODS

8-OHdG content in cellular DNA of leukocytes was measured by a high-performance liquid chromatography-electrochemical detection (HPLC-ECD) method. Intracellular production of ROS, H2O2 and O2-. were analyzed by flow cytometry in leukocytes with and without phorbol-12-myristate-13-acetate (PMA) stimulation before dialysis, as well as at 15 and 30 minutes of dialysis. Plasma alpha-tocopherol concentration was measured by a HPLC method, and the value of alpha-tocopherol was corrected by total blood lipid concentration.

RESULTS

In the prospective cross sectional study, the mean 8-OHdG level in leukocyte DNA was equally lower in the patients of the CL-E, polymethylmethacrylate (PMMA), and polysulfone (PS) groups as compared with the cellulosic group (ANOVA, P < 0.001). The leukocyte 8-OHdG level correlated negatively with plasma alpha-tocopherol and blood lipid-adjusted plasma alpha-tocopherol, but correlated positively with serum iron and percentage of transferrin saturation. Forward stepwise multiple regression showed that dialysis membrane type, serum iron, and blood lipid-adjusted plasma alpha-tocopherol were the independent determinants of the leukocyte 8-OHdG level in HD patients. Like synthetic membranes, granulocyte ROS production was less augmented during dialysis with the CL-E membrane as compared with the cellulose membrane. Exposure to cellulose membrane impaired intracellular ROS production of granulocytes in response to PMA challenge, whereas the CL-E and synthetic membranes improved the granulocyte responsiveness to PMA. In the longitudinal cross-over study, the 8-OHdG level significantly decreased, and blood lipid-adjusted plasma alpha-tocopherol increased after switching the cellulose membrane to CL-E or synthetic membrane for eight weeks. In contrast, the 8-OHdG level dramatically rose, and blood lipid-adjusted plasma alpha-tocopherol declined after shift of CL-E or synthetic membrane to the cellulose membrane.

CONCLUSIONS

CL-E membrane exhibited biocompatible and bioactive characteristics. Like synthetic membranes, treatment with a CL-E dialyzer effectively reduced the 8-OHdG content in leukocyte DNA, suppressed intracellular ROS production of granulocytes, and preserved the plasma level of vitamin E. It could further improve granulocyte responsiveness to a PMA challenge. Reduced DNA damage and improved immune function of leukocytes may reduce the cancer and infection risks in chronic HD patients.