Effect of dialysis on plasma total antioxidant capacity and lipid peroxidation products in patients with end-stage renal failure

Uremic Myopathy and Mitochondrial Dysfunction in Kidney Disease

Alterations in muscle structure and function in chronic kidney disease (CKD) patients are associated with poor outcomes. As key organelles in muscle cell homeostasis, mitochondrial metabolism has been studied in the context of muscle dysfunction in CKD. We conducted a study to determine the contribution of oxidative metabolism, glycolysis and fatty acid oxidation to the muscle metabolism in CKD. Mice developed CKD by exposure to adenine in the diet. Muscle of CKD mice showed significant weight loss compared to non-CKD mice, but only extensor digitorum longus (EDL) muscle showed a decreased number of fibers. There was no difference in the proportion of the various muscle fibers in CKD and non-CKD mice. Muscle of CKD mice had decreased expression of proteins associated with oxidative phosphorylation but increased expression of enzymes and transporters associated with glycolysis. In cell culture, myotubes exposed to uremic serum demonstrated decreased oxygen consumption rates (OCR) when glucose was used as substrate, conserved OCR when fatty acids were used and increased lactate production. In conclusion, mice with adenine-induced CKD developed sarcopenia and with increased glycolytic metabolism but without gross changes in fiber structure. In vitro models of uremic myopathy suggest fatty acid utilization is preserved compared to decreased glucose utilization.

The Behavior of the Type of Peritoneal Transport in the Inflammatory and Oxidative Status in Adults Under Peritoneal Dialysis

Peritoneal dialysis (PD) is an alternative for managing the end-stage renal disease (ESRD). The peritoneal membrane (PM) is not just a membrane that passively responds to diffusion and convection. The characteristics of PM result in the peritoneal equilibrium test (PET) and with this test is possible to obtain the type of peritoneal transport (PT). The patient on PD can be classified in different types of PT as; Low, Low Average, High Average, and High. The aim of the study was to compare the inflammatory cytokines, oxidants, antioxidants, and oxidative DNA damage markers in the different types of PT. A cross-sectional analytical study of 77 adult PD patients was performed. Levels of lipoperoxides (LPO) were higher in all types of PT vs. healthy volunteer controls (HC) (p < 0.0001). Nitric oxide (NO) levels were found significantly down-regulated in all types of PT (p < 0.0001). The activity of the superoxide dismutase enzyme (SOD) was found to be significantly increased in all types of PT vs. the HC (p < 0.0001). The levels of the DNA repair enzyme were found to be decreased in all types of PT. The levels of the pro-inflammatory cytokines TNF-α, IL-6, the marker of oxidative DNA damage, 8-IP and the total antioxidant capacity (TAC) were all significantly decreased, contrary to the levels in HC, possibly by the clearance in the dialysis fluid in all types of PT or due to down-regulation of their expression. In conclusion, we found significant changes in markers of inflammation, oxidative stress, and oxidative damage to DNA in all types of PT; Low, low average, high average, and high PT in the values of D/P creatinine at 4 h compared to HC.

Modified Lipids and Lipoproteins in Chronic Kidney Disease: A New Class of Uremic Toxins

Chronic kidney disease (CKD) is associated with an enhanced oxidative stress and deep modifications in lipid and lipoprotein metabolism. First, many oxidized lipids accumulate in CKD and were shown to exert toxic effects on cells and tissues. These lipids are known to interfere with many cell functions and to be pro-apoptotic and pro-inflammatory, especially in the cardiovascular system. Some, like F2-isoprostanes, are directly correlated with CKD progression. Their accumulation, added to their noxious effects, rendered their nomination as uremic toxins credible. Similarly, lipoproteins are deeply altered by CKD modifications, either in their metabolism or composition. These impairments lead to impaired effects of HDL on their normal effectors and may strongly participate in accelerated atherosclerosis and failure of statins in end-stage renal disease patients. This review describes the impact of oxidized lipids and other modifications in the natural history of CKD and its complications. Moreover, this review focuses on the modifications of lipoproteins and their impact on the emergence of cardiovascular diseases in CKD as well as the appropriateness of considering them as actual mediators of uremic toxicity.

Uremic myopathy: is oxidative stress implicated in muscle dysfunction in uremia?

Renal failure is accompanied by progressive muscle weakness and premature fatigue, in part linked to hypokinesis and in part to uremic toxicity. These changes are associated with various detrimental biochemical and morphological alterations. All of these pathological parameters are collectively termed uremic myopathy. Various interventions while helpful can't fully remedy the pathological phenotype. Complex mechanisms that stimulate muscle dysfunction in uremia have been proposed, and oxidative stress could be implicated. Skeletal muscles continuously produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) at rest and more so during contraction. The aim of this mini review is to provide an update on recent advances in our understanding of how ROS and RNS generation might contribute to muscle dysfunction in uremia. Thus, a systematic review was conducted searching PubMed and Scopus by using the Cochrane and PRISMA guidelines. While few studies met our criteria their findings are discussed making reference to other available literature data. Oxidative stress can direct muscle cells into a catabolic state and chronic exposure to it leads to wasting. Moreover, redox disturbances can significantly affect force production per se. We conclude that oxidative stress can be in part responsible for some aspects of uremic myopathy. Further research is needed to discern clear mechanisms and to help efforts to counteract muscle weakness and exercise intolerance in uremic patients.

Hypoxia and oxidative stress markers in pediatric patients undergoing hemodialysis: cross section study

Background

Tissue injury due to hypoxia and/or free radicals is common in a variety of disease processes. This cross-sectional study aimed to investigate effect of chronic kidney diseases (CKD) and hemodialysis (HD) on hypoxia and oxidative stress biomarkers.

Methods

Forty pediatric patients with CKD on HD and 20 healthy children were recruited. Plasma hypoxia induced factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) were measured by specific ELISA kits while, total antioxidant capacity (TAC), total peroxide (TPX), pyruvate and lactate by enzymatic/chemical colorimetric methods. Oxidative stress index (OSI) and lactate/pyruvate (L/P) ratio were calculated.

Results

TAC was significantly lower while TPX, OSI and VEGF were higher in patients at before- and after-dialysis session than controls. Lactate and HIF-1α levels were significantly higher at before-dialysis session than controls. Before dialysis, TAC and L/P ratio were lower than after-dialysis. In before-dialysis session, VEGF correlated positively with pyruvate, HIF-1α and OSI correlated positively with TPX, but, negatively with TAC. In after-dialysis session, HIF-1α correlated negatively with TPX and OSI; while, OSI correlated positively with TPX.

Conclusions

CKD patients succumb considerable tissue hypoxia with oxidative stress. Hemodialysis ameliorated hypoxia but lowered antioxidants as evidenced by decreased levels of HIF-1α and TAC at before- compared to after-dialysis levels.

Lipid abnormalities and oxidized LDL in chronic kidney disease patients on hemodialysis and peritoneal dialysis

Dyslipoproteinemia and oxidative modification of low-density lipoprotein (oxLDL) contribute to the development of oxidative stress and atherosclerosis in chronic kidney disease (CKD). On the contrary, high-density lipoprotein cholesterol (HDL-C), especially HDL3-C subtype, has protective effect against oxidative damage. There is limited evidence referring HDL-C subclass levels in patients on dialysis. This study was designed to compare lipid abnormalities and oxLDL levels in hemodialysis (HD) and peritoneal dialysis (PD) patients. Serum lipids, HDL subclasses, and oxLDL were measured in 55 patients with CKD-stage 5 (31 patients on HD and 24 patients on PD) and in 21 normal controls (NC). The results showed that in dialysis patients, triglycerides were higher than in controls (p < 0.0001) and HDL-C was significantly lower (p < 0.0001). The HDL2-C subclass concentration did not differ significantly between patients and controls, while HDL3-C was lower in patients (11 ± 0.5 mg/dL) than in NC (23 ± 1, p < 0.0001). oxLDL levels were markedly increased in patients (1.92 ± 0.29 mg/L) compared to NC (0.22 ± 0.05, p < 0.0001). Patients on PD had higher levels of cholesterol (p < 0.001) and apolipoprotein B (p < 0.05) than patients on HD. However, HDL-C, HDL-C subclasses, and oxLDL concentrations did not differ significantly between PD and HD patients. It is concluded that patients with CKD have a nearly 10-fold elevation of oxLDL compared with NC. Patients on PD have differences in the lipid profile compared with patients on HD; however, both modalities seem to possess similar potential to atherosclerosis development.

Comparison of the oxidant-antioxidant parameters and sialic acid levels in renal transplant patients and peritoneal dialysis patients

OBJECTIVE

Several studies have shown that in end-stage renal failure, increased oxidative stress and reduced antioxidant system functions may play an important role in inflammation, atherosclerosis, and many other complications. Paraoxonase (PON) and arylesterase (ARE) are antioxidant and malondialdehyde (MDA) an oxidant agent. Increased sialic acid (SyA) levels in uremic patients is an acute-phase response showing tissue and organ damage. The aim of this study was to compare PON, ARE, MDA, and SyA among continuous ambulatory peritoneal dialysis (CAPD) and renal transplant patients.

METHODS

Twenty-six CAPD patients including 7 women and 19 men of overall mean age 40.5 ± 10.66 years were included in this study. There were 28 preemptive transplant patients, namely 6 women and 22 men of overall mean age 36.5 ± 10.97 years. CAPD was the initial sole replacement therapy. Serum PON, ATE, MDA, and SyA levels were measured at 13-15 months of treatment.

RESULTS

Higher PON (P = .015) and ARE (P = .002) and lower MDA (P = .002) and SyA (P = .000) values were determined among transplanted compared with CAPD patients.

CONCLUSIONS

In the transplant group, antioxidant parameters were higher and oxidant parameters lower with less activation of SyA than in the CAPD group. We observed that renal transplantation had a constructive effect on the oxidant-antioxidant system and consequent tissue destruction, which were impaired in uremic subjects. This study showed that renal transplantation is a more appropriate replacement treatment than CAPD.

CNS peroxiredoxins and their regulation in health and disease

Oxidative stress is thought to be a contributing factor in many chronic neurodegenerative pathologies, as well as acute cerebrovascular disorders such as stroke. Peroxiredoxins are a family of antioxidant enzymes that reduce peroxides directly through the use of a redox active cysteine within their active site, which in the process becomes oxidized. In order to cycle back to the reduced state, many peroxiredoxins rely on thiol-dependent reduction by the ubiquitous antioxidant enzyme thioredoxin. Peroxiredoxins, together with thioredoxin and thioredoxin's own 'recycling enzyme', thioredoxin reductase, represent an antioxidant enzymic system of growing significance in the context of neuronal physiology and pathology. Overexpression, knockdown, and knockout approaches have demonstrated an important role for peroxiredoxins in protecting neurons from oxidative insults. It is also becoming clear that neuronal peroxiredoxins are subjected to post-translational modifications that impair function as part of disease pathology. Conversely, components of this pathway are also subject to dynamic upregulation such as via endogenous synaptic activity-dependent signaling and induction of the Nrf2-dependent Phase II response. As such, the thioredoxin-peroxiredoxin system represents a potential therapeutic target for central nervous system disorders associated with oxidative stress.

Hemodialysis induces p66(shc) gene expression in nondiabetic humans: correlations with oxidative stress and systemic inflammation

OBJECTIVE

Oxidative stress and inflammation characterize hemodialysis (HD) and are associated with malnutrition, cardiovascular disease, and poor clinical outcome. p66(shc) stimulates oxidative stress and atherogenesis. The objective of the present study was to assess p66(shc) expression levels in HD and their associations with inflammatory and oxidative stress markers.

DESIGN

p66(shc) messenger ribonucleic acid (mRNA) was compared with systemic oxidative stress and inflammation markers in control subjects and patients on HD before and after a single HD session in a cross-sectional analysis.

SETTING

Outpatient hemodialysis unit.

PATIENTS

The study included stable HD patients (n = 21, men/women: 18/3) who were on HD 3 times per week for a minimum of 8 weeks; age-matched control subjects (n = 22, men/women:17/5).

MAIN OUTCOME MEASURE

mRNA levels of p66(shc), tumor necrosis factor α (TNF-α), and pentraxin 3 (PTX3), p66(shc) protein levels in white blood cells, lipid peroxidation (in the form of plasma thiobarbituric acid-reactive substance [TBARS]) and serum C-reactive protein.

RESULTS

In patients on dialysis, of the p66(shc), TNF-α, and PTX3 mRNAs, p66(shc) protein levels were higher (P < .05) than in control subjects, as well as plasma TBARS and C-reactive protein (P < .05). p66(shc) mRNA directly correlated with TBARS (r = 0.69, P = .0005) and with TNF-α mRNA (r = 0.63, P = .003). These associations were confirmed in the whole study population (TBARS: r = 0.541, P = .0003; TNF-α: r = 0.581, P < .0001), whereas in the control group only the positive association between p66(shc) and TNF-α was detected. TNF-α was directly correlated with PTX3 both in HD patients (r = 0.72, P = .0005) and in the whole study group (r = 0.678, P < .0001). The dialysis session affected neither p66(shc) and TNF-α mRNA nor p66(shc) protein expression, whereas it further increased (P = .002) PTX3 mRNA. As compared with predialysis levels, TBARS were reduced (P < .05) after dialysis. In these conditions, p66(shc) remained directly correlated with TNF-α (r = 0.901, P < .0001).

CONCLUSIONS

Increased p66(shc) gene expression correlates with TNF-α mRNA and with levels of markers of oxidative stress in HD. We suggest a novel link between HD-associated inflammation and p66(shc) gene expression contributing to systemic oxidative stress.

Hemodialysis alters lipid profiles, total antioxidant capacity, and vitamins A, E, and C concentrations in humans

Although hemodialysis (HD) is essential for end-stage renal disease patients, at the same time it causes oxidative stress and long-term pro-atherosclerotic effects. This study aimed to determine lipid profile as well as the total antioxidant capacity (TAC) and vitamins A, E, and C in HD patients. The study enrolled 31 patients (50.3 ± 14.9 years old) undergoing maintenance 4-hour HD three times per week with a polysulfone membrane dialyzer for a mean of 76.1 months (range, 7-120 months) and 31 healthy individuals (47.8 ± 13.9 years old). Lipid profiles were determined spectrophotometrically using commercially available kits. Total antioxidant capacity was determined by ferric reducing/antioxidant power assay, levels of vitamins A and E were assayed using high-pressure liquid chromatography, and the level of vitamin C was measured by a photometric method. Our results showed that before HD, the levels of TAC and vitamin A were significantly higher than in normal subjects, whereas the levels of high-density lipoprotein (HDL) and vitamin C were lower than in control subjects (P < .001). There was no significant difference between normal subjects and patients before dialysis regarding low-density lipoprotein (LDL) and vitamin E levels (P > .05). After HD, the levels of HDL-cholesterol, vitamins E and C, and TAC decreased significantly (P < .001), but the decreased level of vitamin A still remained higher than controls (P < .05), whereas the levels of LDL were significantly higher than controls (P < .001). In conclusion, alterations in the lipoprotein profiles and antioxidant markers following HD suggest an increased risk of atherosclerosis in these patients.

The importance of oxidative stress in patients with chronic renal failure whose hypertension is treated with peritoneal dialysis

Increased oxidative stress is a well-known phenomenon in dialysis patients. However, the contribution of hypertension to the oxidative stress in peritoneal dialysis patients has not yet been assessed. The present study aimed to investigate if hypertension had an additional effect on oxidative stress in peritoneal dialysis patients. A total of 50 patients treated with peritoneal dialysis were divided into two groups: The patients with mean of last three blood pressure results as 135/90 mmHg and above were considered hypertensive, the patients with lower blood pressure were considered normotensive. The control group included 25 healthy individuals. Serum malondialdehyde (MDA), advanced oxidation protein product (AOPP), myeloperoxidase (MPO), catalase (CAT) and glutathione peroxidase (GSH-Px) levels were measured in all groups. MDA level, an indicator of lipid peroxidation, was significantly higher in the hypertensive group compared to the control group, while the increase in the normotensive group was not significant. However, the difference between the hypertensive and normotensive groups was significant. The levels of AOPP, an indicator of protein oxidation level, and MPO, an indicator of neutrophil activation, were not different between the groups, while the activities of antioxidant CAT and GSH-Px decreased in both normotensive and hypertensive groups compared to the control group, and there was no significant difference between the patient groups. This study shows that both normotensive and hypertensive peritoneal dialysis patients have increased-oxidative stress and decreased antioxidant levels and hypertension might have an additional effect on oxidative stress by increasing MDA level in peritoneal dialysis patients.

Comparison Between the Antioxidant Level of Uremic Patients Before and After Hemodialysis (Hd) and Vitamin E Therapy: Prospective cohort study

A prospective cohort study of 18 males aged 19–45 years with chronic renal failure attending the Ibn Sina Teaching Hospital, Mosul for Hemodialysis (HD) between March 2007 and March 2008 assessed the oxidative stress, antioxidant status, serum urea and serum creatinine before and after hemodialysis and following subsequent supplementation with oral Vitamin E. Blood samples collected before starting hemodialysis, after three weeks of twice-weekly dialysis, and then after three weeks of oral vitamin E (400 i.u/day) showed significant decreases of total antioxidant status (TAS) after HD but a significant increase of TAS after Vitamin E therapy; a non-significant increase of lipid peroxidation indicator (serum malondialdehyde; MDA) after HD alone but a significant decrease of MDA after Vitamin E therapy; a highly significant decrease of serum urea after HD and a highly significant increase of serum urea after Vitamin E therapy; a highly significant decrease of serum creatinine after HD and a highly significant increase of serum creatinine after Vitamin E therapy; a highly significant decrease of serum uric acid after HD and a highly significant increase of serum uric acid after Vitamin E therapy. There were non-significant correlations between TAS and MDA, uric acid, serum urea and serum creatinine after HD and after Vitamin E therapy. It is concluded that in patients with chronic renal failure oxidative stress is further exacerbated, as shown by decreased TAS and increased MDA although serum uric acid is not the sole contributor. Vitamin E supplementation in such patients after HD does not enhance renal function but it decreases the oxidative stress by decreasing MDA and enhancing antioxidant body status by increasing significantly TAS and serum uric acid.

Erythrocyte transmembrane electron transfer in haemodialysis patients

BACKGROUND AND AIMS

Patients with chronic renal failure, especially those treated with haemodialysis, have an increased risk of developing atherosclerotic vascular disease probably as a result of enhanced oxidative stress. The human cell membrane possesses electron transfer systems which protect against extracellular pro-oxidant challenge. We evaluated (1) the erythrocyte velocity of ferricyanide reduction (RBC vfcy) in 25 uraemic patients (aged 25-71 years; 14 males), (2) the changes induced by a single haemodialysis session and (3) biomarkers of oxidative stress.

METHODS AND RESULTS

Before and after a mid-week dialysis session, we measured RBC vfcy, erythrocyte glutathione (RBC GSH), plasma and red cell membrane malondialdehyde (P and RBC MDA), plasma sulphydryl groups (P SH), plasma vitamin C levels and haemolysis percentage. Pre-dialysis RBC GSH (0.68+/-0.13 vs 0.80+/-0.13 mg/mL, p<0.01), P SH (266+/-74 vs 406+/-78 micromol/L, p<0.01) and plasma vitamin C (7.0+/-5.1 vs 21.5+/-8.5mg/L, p<0.001) were lower than in 25 age-sex-matched healthy controls; P MDA (1.57+/-0.52 vs 0.54+/-0.29 nmol/mL, p<0.001), RBC MDA (0.42+/-0.13 vs 0.34+/-0.16 nmol/mL, p<0.05) and haemolysis (1.2+/-0.3 vs 0.7+/-0.3%, p<0.001) were increased. Baseline RBC vfcy did not differ from normals (13.1+/-5.2 vs 12.9+/-3.2 mmol/mL/h). Following dialysis, RBC vfcy (to 8.9+/-4.5 mmol/mL/h, p<0.001) decreased, as well as P MDA, RBC MDA and plasma vitamin C (to 2.5+/-1.4 mg/L, p<0.001), whereas P SH groups increased (to 413+/-99 micromol/L, p<0.001); haemolysis percentage remained high. RBC vfcy values were correlated to RBC GSH and vitamin C levels.

CONCLUSIONS

Uraemic patients showed signs of oxidative stress. Pre-dialysis RBC vfcy is maintained in the normal range on account of a reduced intracellular content of GSH and in spite of low plasma ascorbate. A single haemodialysis treatment reduced biomarkers of protein and lipid oxidation but markedly impaired transmembrane electron transfer, which could be explained by acute depletion of electron donors.

The application of proteomics and genomics to the study of age-related neurodegeneration and neuroprotection

The present study aimed to acquire more information on aging-related alterations, using proteomic and genomic analyses of hippocampus from young (8 months) and old (27 months) rats. In the old rats, the proteomic analysis identified changes in proteins related to the iron-mediated oxidative stress (OS) pathway, including reduction in antioxidant enzymes (e.g., peroxiredoxin, cytochrome c oxidase) and induction of ferritin. Furthermore, the neurofilament light peptide, associated with neurodegenerative processes, was enhanced and binding/ chaperone proteins were altered in old vs. young rats. At the genes levels, significant molecular changes related to neurodegeneration were identified in aged rat hippocampus. Thus, the effects of the potent neuroprotective compounds, the anti-Parkinson drug, rasagiline and the anti-Alzheimer drug, ladostigil (1 mg/kg, for 30 days) on gene expression in the hippocampus were further investigated. Both drugs reversed the effect of aging on the expression of various mitochondrial and key regulator genes involved in neurodegeneration, cell survival, synaptogenesis, oxidation, and metabolism. These results support the hypothesis that OS and mitochondrial dysfunction may play a pivotal role in aging and age-associated neurodegenerative diseases, and can serve as potential clinical targets for future therapy.

Reactive Oxygen Metabolites: A Link between Oxidative Stress and Inflammation in Patients on Hemodialysis

Oxidative stress plays a significant role in the development of inflammation in patients undergoing hemodialysis (HD). This study intends to evaluate the relationship between C-reactive protein (CRP) and the newly established marker of lipid peroxidation, d-ROMs (reactive oxygen metabolites), in comparison with different indicators of oxidative stress. Plasma total antioxidant capacity (TAC), lipid peroxidation products malonaldehyde (MDA) and 4-hydroxyalkenals, as well as d-ROMs, were determined in 24 patients before HD and in 21 normal controls (NC). It was found that HD patients had higher levels of d-ROMs than NC (p = 0.033). A highly significant positive correlation was observed between logCRP and d-ROMs concentrations (p < 0.0001, r = 0.85) in patients, but not in NC. The concentrations of TAC and MDA were not associated with CRP in HD or in NC individuals. It is concluded that d-ROMs concentration is a potent marker of oxidative injury that is strongly indicative of the inflammatory status in HD patients.

Proteomic identification of lower apolipoprotein A-I in Alzheimer's disease

Many researches have been trying to find the potential biomarkers for Alzheimer's disease (AD). We hereby used the proteomics method to search for protein expression differences in the serum between AD patients and controls. We enrolled 59 AD patients and 74 age- and sex-matched controls in this study. Ten AD patients and 10 controls were selected for proteomic analysis. Apolipoprotein A-I (ApoA-I) was found to have a lower expression in the AD group by a proteomics two-dimensional gel electrophoresis study. We further measured the serum ApoA-I level which was significantly lower in the AD patients (112.29 +/- 21.33 mg/dl) in comparison to the controls (144.53 +/- 19.91 mg/dl; p < 0.0002). Lower serum ApoA-I levels might be a potential biomarker for AD.

Lipid peroxidation and antioxidant enzymes in children on maintenance dialysis

End-stage renal disease (ESRD) is associated with numerous complications, which may partly result from excessive amounts of reactive oxygen species and/or decreased antioxidant activity. The aim of the study was to evaluate lipid peroxidation (LP) in plasma and erythrocytes, erythrocyte antioxidant enzyme activity (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GSH-Px), and concentrations of Cu and Zn as cofactors of SOD and Se as a cofactor of GSH-Px in erythrocytes, plasma and in dialysis fluid in children with ESRD. In particular, we analyzed whether the modality of dialysis could modify oxidative stress parameters in children. To determine the influence of hemodialysis (HD) on oxidative stress, the measurements were also performed on HD children 20 min after the beginning of the dialysis session. Thirty-one patients participated in the study: group I with 10 children on continuous ambulatory peritoneal dialysis (CAPD), and group II with 21 on HD. The erythrocyte malondialdehyde concentrations (E-MDA), plasma MDA (P-MDA) and plasma organic hydroperoxide (OHP) in children from both groups were higher than in controls. E-MDA and P-MDA in HD before the session was lower compared to the values after 20 min of HD session (time T20). The activity of SOD, GSH-Px, CAT, concentrations of erythrocyte and plasma Se, Cu, Zn were lower in children with ESRD than in controls. In the HD group, the activity of GSH-Px, CAT, and levels of trace elements in erythrocytes and in plasma were diminished at time T20. In conclusion, increased oxidative stress occurs in children on maintenance dialysis, independent of dialysis modality. The activity of the enzymatic antioxidant defence system is highly reduced in red blood cells of pediatric dialysis patients. Children with ESRD exhibit lower trace element (Se, Cu, Zn) levels in plasma and erythrocytes as compared to healthy subjects. Oxidative stress is aggravated during every single HD session in children.

Myeloperoxidase serves as a marker of oxidative stress during single haemodialysis session using two different biocompatible dialysis membranes

BACKGROUND

There is increased oxidative stress in patients undergoing haemodialysis (HD); however, little is known of how different dialysis membranes contribute to the oxidative stress induced by the dialysis procedure per se. We therefore studied the influence of two different dialysis membranes on oxidative stress during HD.

METHODS

Eight patients undergoing HD three times per week were enrolled in this cross-controlled study. Patients sequentially received HD using polysulphone (PS) and regenerated cellulose (RC) dialysis membranes for 1 week each. Blood samples were collected in the last section of each hollow fibre 0, 15, 120 and 240 min after starting HD. We determined superoxide anion production derived from neutrophils, superoxide dismutase (SOD) and glutathione peroxidase (GPx) derived from washed red cells, plasma myeloperoxidase (MPO), plasma thiobarbituric acid-reactive substances (TBARS), plasma advanced oxidation protein products (AOPP) and serum 8-hydroxy-2'-deoxyguanosine (8-OHdG).

RESULTS

Leukocyte numbers, including neutrophils, lymphocytes and monocytes, decreased significantly after 15 min of dialysis, more so with RC than with PS membrane. For both membranes, superoxide anion production transiently increased during the first 15 min whereas the post-dialysis production was decreased. Plasma MPO levels persistently increased during dialysis with the two membranes. Moreover, the increase was more marked with RC than with PS membrane. AOPP and 8-OHdG levels increased progressively when using RC membranes. There were no significant differences in SOD, GPx, TBARS, AOPP and 8-OHdG levels between the two membranes.

CONCLUSIONS

The biocompatibility of the dialyser affects oxidative stress production during a single dialysis session. The measurement of MPO may serve as a reliable marker of the degree of oxidative stress induced using dialysis membranes of different biocompatibilities.