Chemiluminescence and superoxide anion production by leukocytes from chronic hemodialysis patients

Oxidative Metabolism of Polymorphonuclear Leukocytes in Continuous Ambulatory Peritoneal Dialysis

Objective

To evaluate the oxidative metabolism of polymorphonuclear leukocytes (PMNL) in continuous ambulatory peritoneal dialysis (CAPD) patients compared with those of hemodialysis (HD) patients, chronic renal failure (CRF) patients not yet on dialysis, and healthy controls; and to discover factors contributing to the oxidative function in CAPD patients.

Patients

Thirty-five CAPD, 22 HD, 11 CRF patients were assessed; all were free from infections at the time of examination. Thirty-one healthy volunteers served as controls.

Methods

The oxidative metabolism was estimated by the production of superoxide anion, which was detected by luminol-dependent zymosan stimulated chemiluminescence (CL) with whole blood assessment. The volume of superoxide production equivalent to 1 mL of circulating blood (T-CL), that equivalent to 104 neutrophils (CL/N) and the velocity of superoxide production (V-CL), were measured as parameters for the oxidative function of PMNL.

Results

There were no differences in all CL parameters between CAPD and HD patients. T -CL and CL/N of dialysis patients were equal to controls but those of CRF patients were significantly decreased. V-CL of dialysis patients, as well as CRF patients, was smaller than that of controls but the difference was not significant. Among nutritional status, degree of anemia, dialytic efficacy and duration of dialysis in CAPD patients, only serum albumin concentration (Alb) correlated well to all CL parameters. Hypoalbuminemic patients(Alb <3.6 gldL, n=20) had significantly decreased T -CL and CL/N compared to normoalbuminemic patients(Alb ?: 3.6 g/dL, n=15), and decreased CL/N and V-CL compared to controls. No differences in CL parameters were observed between the patients with a history of peritonitis (n=15) and without a history of peritonitis (n=20).

Conclusions

Oxidative metabolism of PMNL in CAPD patients was maintained with respect to superoxide productive volume, while the oxidative velocity was relatively impaired. Furthermore, it seems that albumin has a great influence on the oxidative metabolism of PMNL in CAPD patients.

Influence of Membranes on Generation of β2 M and Release of Leukocyte Lysosomal Enzymes

Normal leukocyte functional capacity was investigated by evaluation of phagocytosis of opsonised yeast cells in a radiometric test system. After incubation with dialysis membranes (different cellulosic membranes, polysulfon membrane (PS), polymethylmetacrylate membrane (PMMN), the phagocytosis index, expressed as percent decrease with respect to initial values without membrane, decreased by 10%–25%. The most pronounced effect was observed with PS, cuprophane, modified cellulose and PMMA. The results are not related to differences in the viability of PMN during the test procedure; dead PMN amounted to about 4–6.5%. A significant increase in β-NAG and β-Gluc activities was released in the supernatants of the phagocytosis suspensions. This increase activity can be explained by the phagocytosis of PMN but it was not influenced by membrane contact. There was no influence of membrane contact or phagocytosis activity of PMN on the β2M concentration in the supernatant demonstrating that no in vitro generation during incubation with either membrane exists.

Parietin: an efficient photo-screening pigment in vivo with good photosensitizing and photodynamic antibacterial effects in vitro

The photophysical, photoinduced pro-oxidant and antibacterial properties in vitro of the natural occurring parietin (PTN; 1,8-dihydroxy-3-methoxy-6-methyl-9,10-anthraquinone) were evaluated. PTN was extracted from the lichen identified as Teloschistes flavicans (Sw.) Norm. (Telochistaceae). Results indicate that in chloroform solution, PTN presents spectroscopic features corresponding to an excited-state intramolecular proton-transfer (ESIPT) state with partial keto-enol tautomerization. In argon-saturated solutions, the singlet excited state is poorly fluorescent (Φ_F = 0.03), decaying by efficient intersystem crossing to an excited triplet state ³PTN*, as detected by laser-flash photolysis experiments. In the presence of triplet molecular oxygen, the ³PTN* was fully quenched producing singlet molecular oxygen (¹O₂) with a quantum yield of 0.69. In addition, in buffer solutions, PTN has the ability to also generate a superoxide radical anion (O₂˙^-) in a human leukocyte model and its production was enhanced under UVA-Vis irradiation. Finally, the in vitro antibacterial capability of PTN in the dark and under UVA-Vis illumination was compared in microbial cultures of both Gram positive and negative bacteria. As a result, PTN showed promising photo-induced antibacterial activity through the efficient photosensitized generation of both ¹O₂ and O₂˙^- species. Thus, we have demonstrated that PTN, an efficient photo-screening pigment in lichens, is also a good photosensitizer in solution with promising applications in antibacterial photodynamic therapy.

Assessing immunologic risk factors in transplantation

The innate and adaptive immune systems, together, represent the largest impediment to good and long-lasting graft function. Although improved immunosuppressive agents and expanded and enhanced diagnostic tools have led to better prevention and treatment of acute rejection, chronic rejection remains a serious threat to long-term graft survival. Immunologic heterogeneity among patients, variability in treatment protocols and unforeseen events following transplantation translate into different levels of risk among patients. While one cannot predict with certainty the short- and long-term outcomes of a particular transplant, it is possible to identify immunologic risk factors that can affect outcome.

Effect of leptin on polymorphonuclear leucocyte functions in healthy subjects and haemodialysis patients

BACKGROUND

Dysfunction of polymorphonuclear leucocytes (PMNLs) in end-stage renal disease (ESRD) patients contributes to a diminished immune defence. The serum levels of leptin are elevated in patients with ESRD. We analysed in vitro effects of leptin on PMNLs from healthy subjects (HS; n = 12) and haemodialysis (HD) patients (n = 15) before and after HD.

METHODS

PMNL oxidative burst and phagocytosis were tested by flow cytometry in whole blood. Chemotaxis of isolated PMNLs was assessed by the under-agarose method. To assess the involvement of leptin in PMNL signalling pathways, signal transduction inhibitors were used and the activity of intracellular kinases was investigated by western blotting, in vitro kinase assays and the Luminex technology.

RESULTS

Increasing the leptin level in the blood of HS leads to a reduced activation of the oxidative burst by Escherichia coli and phorbol 12-myristate 13-acetate. Activation of the oxidative burst is reduced in the blood of HD patients and the addition of leptin does not lead to further PMNL inhibition. Leptin at a concentration measured in HD patients significantly reduces the chemotaxis of PMNLs from HS but had no effect on PMNLs from ESRD patients before and also after HD treatment with high-flux dialysers. The phosphoinositide 3-kinase/Akt pathway is involved in the inhibitory effects of leptin.

CONCLUSIONS

In the presence of leptin, PMNLs from HS and HD patients respond differently to stimuli. The lack of response to leptin in PMNLs from HD patients cannot be influenced by HD.

Particle-induced myeloperoxidase release in serially diluted whole blood quantifies the number and the phagocytic activity of blood neutrophils and opsonization capacity of plasma

Luminol-amplified chemiluminescence (CL) from phagocytes has previously been shown to be almost completely dependent on the release of myeloperoxidase (MPO) from azurophilic granules. We measured the luminol-amplified chemiluminescence response (WBCL) by using serially diluted whole blood. In these experiments, non-opsonized and serum-opsonized zymosan (NWBCL and OWBCL, respectively) were used concurrently as phagocytosable particles. We found two whole-blood dilution ranges with clinical significance: first, <0.04% of whole blood in the reaction volume, where MPO released by the zymosan-activated leukocyte population came almost totally from neutrophils and the OWBCL response could be exploited as a measure of a neutrophil count in a given blood specimen, despite the pathophysiological state of the host. In contrast, the NWBCL response was two-fold in blood samples from bacterial infection patients compared to those of controls and patients with viral infection, suggesting the use of NWBCL for the differential diagnosis of bacterial infections from viral infections; second, 0.16-1.2% of whole blood in the reaction volume, where the opsonization capacity of plasma (OC(50)) can be determined. We also found that at whole blood content >0.04%, erythrocytes quickly start to absorb chemiluminescence light, and that at whole blood content >1.2%, plasma proteins, most probably albumin and fibrinogen, start to inhibit MPO release.

Protective effects of a standard extract of Mangifera indica L. (VIMANG) against mouse ear edemas and its inhibition of eicosanoid production in J774 murine macrophages

A standard aqueous extract of Mangifera indica L., used in Cuba as antioxidant under the brand name VIMANG, was tested in vivo for its anti-inflammatory activity, using commonly accepted assays. The standard extract of M. indica, administered orally (50-200mg/kg body wt.), reduced ear edema induced by arachidonic acid (AA) and phorbol myristate acetate (PMA) in mice. In the PMA model, M. indica extract also reduced myeloperoxidase (MPO) activity. In vitro studies were performed using macrophage cell line J774 stimulated with pro-inflammatory stimuli lipopolysaccharide-interferon gamma (LPS-IFNgamma) or calcium ionophore A23187 to determine prostaglandin PGE(2) or leukotriene LTB(4) release, respectively. The extract inhibited the induction of PGE(2) and LTB(4) with IC(50) values of 21.7 and 26.0microg/ml, respectively. Mangiferin (a glucosylxanthone isolated from the extract) also inhibited these AA metabolites (PGE(2), IC(50) value=17.2microg/ml and LTB(4), IC(50) value=2.1microg/ml). These results represent an important contribution to the elucidation of the mechanism involved in the anti-inflammatory and anti-nociceptive effects reported for the standard extract of M. indica VIMANG.

Vibrio vulnificus Peritonitis After Handling of Seafood in a Patient Receiving CAPD

Vibrio vulnificus is a marine bacterium and opportunistic human pathogen. Associated infections have contributed to the majority of seafood-related deaths in the United States. In patients with such predisposed clinical conditions as chronic liver disease, immunocompromised state, and end-stage renal disease, this organism has been associated with the development of life-threatening primary septicemia and severe wound infection. However, continuous ambulatory peritonitis dialysis (CAPD)-related peritonitis caused by V vulnificus has not been reported. We describe a patient receiving CAPD who developed peritonitis caused by V vulnificus after handling seafood. This case highlights the importance of strict aseptic technique during CAPD exchanges and calls for an effort in educating our dialysis patients on precautions about seafood handling.

Vibrio vulnificus infection in a hemodialysis patient receiving intravenous iron therapy

A 73-year-old man treated with long-term hemodialysis, erythropoietin, and intravenous iron sucrose infusions developed Vibrio vulnificus infection after eating raw oysters harvested from the Alabama coast. Five of the 31 persons with cases of V. vulnificus infection reported to the Alabama Department of Public Health (Montgomery) during 1996-2002 (including the patient described here) also had renal disease. Persons with renal disease, especially those treated with long-term hemodialysis and intravenous iron infusions, may have an increased risk of infection with V. vulnificus.

Toxicity of free p-cresol: a prospective and cross-sectional analysis

BACKGROUND

Uremic syndrome is the consequence of the retention of solutes usually cleared by the healthy kidneys. p-Cresol can be considered a prototypic protein-bound uremic toxin. It is conceivable, analogous with drugs, that the non-protein-bound fraction of p-cresol exerts toxicity. This aspect had never been evaluated, nor have the factors influencing the free fraction of p-cresol.

METHODS

In a transsectional study we evaluated the relationship between prehemodialysis free p-cresol and the ratio of free to total p-cresol (F:T) to clinical and biological factors in 44 chronic renal failure patients. The evolution of free p-cresol was assessed prospectively in 12 patients showing a change in serum albumin of at least 5 g/L over time. Hospitalization days attributable to infection and the free p-cresol concentrations were noted over a 1-year period. The impact of free p-cresol in vitro on leukocyte functional capacity was evaluated by chemiluminescence.

RESULTS

We observed a correlation between total and free p-cresol (r = 0.84; P <0.001). In the multivariate analyses, free p-cresol and F:T showed a negative correlation with albumin. A shift from normal serum albumin to hypoalbumininemia in 12 patients led to an increase in free p-cresol from 5.9 +/- 3.2 to 8.2 +/- 4.5 micro mol/L (P <0.05; 0.64 +/- 0.35 to 0.89 +/- 0.49 mg/L). Free p-cresol (P <0.05) was higher in the patients hospitalized for infectious disease. In vitro, free p-cresol was higher in a 25 g/L than in a 50 g/L albumin solution (P <0.05). Leukocyte chemiluminescence production was more inhibited in the low albumin (high free p-cresol) solution (28% +/- 6% vs 21% +/- 8%; P <0.05).

CONCLUSIONS

Hypoalbuminemia and total p-cresol increase the free fraction of p-cresol. Patients hospitalized for infections have higher free p-cresol. In vitro, high free p-cresol has a negative impact on leukocyte chemiluminescence production. These data demonstrate the toxicity of free p-cresol.

Vitamin E-bonded hemodialyzer improves neutrophil function and oxidative stress in patients with end-stage renal failure

We evaluated the biocompatibility of a newly developed vitamin E hemodialyzer (CL-EE; Terumo Co Ltd, Tokyo, Japan) by neutrophil function and oxidant stress in patients with end-stage renal failure in a randomized crossover study. Ten patients underwent hemodialysis using either the CL-EE or a control dialyzer membrane identical to the CL-EE except for vitamin E binding for 12 weeks in a crossover fashion after a 1-month washout period with hemophane membranes. White blood cell counts, serum oxidized low-density lipoprotein (Ox-LDL) levels, and malondialdehyde (MDA) levels during hemodialysis sessions were measured at the initiation and end of the CL-EE and control trials. Superoxide anion production by neutrophils just before and 4 hours after starting the session also was measured. Leukocytopenia at 1 hour after starting the session was detected to a similar extent in both membranes. However, the degree of reduction was less in the CL-EE trial after repeated use. Superoxide anion production by neutrophils just before a hemodialysis session was reduced after repeated use of the CL-EE membrane. Serum Ox-LDL levels increased, whereas serum MDA levels decreased during sessions to a similar extent in both trials. However, these parameters were significantly lower in the CL-EE trial after repeated use. Serum LDL concentrations significantly decreased with repeated use of the CL-EE membrane. These data suggest that repeated use of the CL-EE membrane for 3 months improves neutrophil function, oxidant stress, and LDL concentrations in patients with renal failure. This membrane may be useful to reduce the incidence of cardiovascular events in patients with renal failure.

Effects of a vitamin E-modified dialysis membrane on neutrophil superoxide anion radical production

Activation of neutrophil by the dialysis membrane and peroxidative stress plays an important role on the pathogenesis of complications in hemodialysis (HD) patients. Vitamin E is one of the potent scavengers for reactive oxygen species. Recent studies suggest that a vitamin E-modified multilayer membrane (Excebrane, CL-EE dialyzer) has an inhibitory effect on serum lipids peroxidation in HD patients. To determine the effect of CL-EE on biocompatibility in clinical use, we measured the superoxide anion radical producing ability (SOPA) of polymorphonuclear leukocytes (PMNLs), the plasma hydroxyl radical producing ability (OHPA) and superoxide anion radical scavenging activity (SSA). SOPA was measured after stimulation of PMNLs with phorbol myristate acetate using electron paramagnetic resonance (EPR) method. Plasma OHPA and SSA were also determined using the EPR method. In addition, the plasma concentrations of malondialdehyde (MDA) and oxidized low-density lipoprotein (LDL), as the parameters for lipid peroxidation, were measured. SOPA was decreased in patients who used conventional filter membrane compared with healthy controls. In the patients using the CL-EE membrane, SOPA gradually increased and reached control levels after six months. However, no significant increase was observed in patients who used a conventional filter membrane. OHPA of HD patients was significantly decreased compared with controls. In the CL-EE membrane patient group, OHPA was significantly increased at six months. SSA was significantly higher in the conventional filter membrane group than controls. In the CL-EE membrane patient group, SSA gradually decreased at six months. Plasma MDA and oxidized LDL levels were significantly higher in HD patients compared with controls. These values slowly decreased, and significant differences were found after nine months of using the CL-EE membrane. These findings suggest that activation of PMNLs and plasma OHPA and SSA in HD patients is attenuated by antioxidant effects of the CL-EE.

Uremic toxins modulate the spontaneous apoptotic cell death and essential functions of neutrophils

Clearance of neutrophils via apoptosis from the site of infection is crucial for the coordinated resolution of inflammation. The balance between stimulating and attenuating as well as between pro- and anti-apoptotic factors is necessary for maintenance of an effective immune response without the harmful side effects of neutrophil action. This article describes the effect of glucose-modified serum proteins and of free immunoglobulin light chains (IgLCs) on neutrophil functions and apoptosis. Both groups of proteins are found at elevated levels in sera of uremic patients. Glucose-modified proteins increase both the chemotactic movement of neutrophils and the activation of glucose uptake. Spontaneous neutrophil apoptosis is increased in the presence of these modified serum proteins. On the other hand, the presence of free IgLCs, previously shown to diminish neutrophil chemotaxis and the activation of glucose uptake, increase the percentage of viable neutrophils by inhibiting spontaneous apoptotic cell death. We conclude that both glucose-modified proteins and free IgLCs can be considered to be uremic toxins and both contribute to the disturbed immune function in uremic patients. Their concentrations as well as the microenvironment in which they are acting seem to be important for their actual effects.

Protective effects of Mangifera indica L. extract, mangiferin and selected antioxidants against TPA-induced biomolecules oxidation and peritoneal macrophage activation in mice

We compared the protective abilities of Mangifera indica L. stem bark extract (Vimang) 50-250 mgkg(-1), mangiferin 50 mgkg(-1), vitamin C 100 mgkg(-1), vitamin E 100 mgkg(-1)and beta -carotene 50 mgkg(-1)against the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced oxidative damage in serum, liver, brain as well as in the hyper-production of reactive oxygen species (ROS) by peritoneal macrophages. The treatment of mice with Vimang, vitamin E and mangiferin reduced the TPA-induced production of ROS by the peritoneal macrophages by 70, 17 and 44%, respectively. Similarly, the H(2)O(2)levels were reduced by 55-73, 37 and 40%, respectively, when compared to the control group. The TPA-induced sulfhydryl group loss in liver homogenates was attenuated by all the tested antioxidants. Vimang, mangiferin, vitamin C plus E and beta -carotene decreased TPA-induced DNA fragmentation by 46-52, 35, 42 and 17%, respectively, in hepatic tissues, and by 29-34, 22, 41 and 17%, in brain tissues. Similar results were observed in respect to lipid peroxidation in serum, in hepatic mitochondria and microsomes, and in brain homogenate supernatants. Vimang exhibited a dose-dependent inhibition of TPA-induced biomolecule oxidation and of H(2)O(2)production by peritoneal macrophages. Even if Vimang, as well as other antioxidants, provided significant protection against TPA-induced oxidative damage, the former lead to better protection when compared with the other antioxidants at the used doses. Furthermore, the results indicated that Vimang is bioavailable for some vital target organs, including liver and brain tissues, peritoneal exudate cells and serum. Therefore, we conclude that Vimang could be useful to prevent the production of ROS and the oxidative tissue damages in vivo.

Mn-porphyrin derivatives as an antioxidant for medical devices

It is well known that reactive oxygen species such as O*2- and H2O2 induce the biodegradation or cracking of medical devices in vivo or that they are released from inflammatory cells activated by devices to oxidize low-density lipoprotein. Therefore, the development of a novel antioxidant is required to eliminate the reactive oxygen species. In this paper, we report that Mn-porphyrin derivatives containing a macromolecular Mn-porphyrin are relatively stable compounds that can eliminate O*2- and/or H2O2. The dismutation of O*2- in the porphyrins was determined using a cytochrome c-assay by the xanthine/xanthine oxidase system and using the stopped-flow kinetic analysis technique. The possibility of porphyrins as scavengers of H2O2 was evaluated by in situ measurement with a Clark electrode. As a result, it has been found that Mn-porphyrin derivatives may be a vastly better scavenger of reactive oxygen species in vivo.

Smokeless tobacco, oxidative stress, apoptosis, and antioxidants in human oral keratinocytes

We have investigated the effects of a smokeless tobacco extract (STE) on lipid peroxidation, cytochrome c reduction, DNA fragmentation and apoptotic cell death in normal human oral keratinocyte cells, and assessed the protective abilities of selected antioxidants. The cells, isolated and cultured from human oral tissues, were treated with STE (0-300 microl;g/ml) for 24 h. Superoxide anion production was determined by cytochrome c reductase. Oxidative tissue damage was determined by lipid peroxidation and DNA fragmentation, whereas apoptotic cell death was assessed by flow cytometry. STE-induced fragmentation of genomic DNA was also determined by gel electrophoresis. The comparative protective abilities of vitamin C (75 microM), vitamin E (75 microM), a combination of vitamins C & E (75 microM each), and a novel grape seed proanthocyanidin (IH636) extract (GSPE) (100 microg/ml) against STE induced oxidative stress and tissue damage were also determined. Following treatment of the cells with 300 microg STE/ml 1.5-7.6-fold increases in lipid peroxidation, cytochrome c reduction and DNA fragmentation were observed. The addition of the antioxidants to cells treated with STE provided 10-54% decreases in these parameters. Approximately 9, 29, and 35% increases in apoptotic cell death were observed following treatment with 100, 200, and 300 microg STE/ml, respectively, and 51-85% decreases in apoptotic cell death were observed with the antioxidants. The results demonstrate that STE produces oxidative tissue damage and apoptosis, which can be attenuated by antioxidants including vitamin C, vitamin E, a combination of vitamins C plus E and GSPE. GSPE exhibited better protection against STE than vitamins C and E, singly and in combination.

Neutrophil apoptosis and dysfunction in uremia

The high prevalence of bacterial infections among patients with end-stage renal disease suggests that "professional" phagocytes such as neutrophils are functionally impaired. This dysfunction has been ascribed to uremic toxins, malnutrition, and dialysis. The aim of this study was to investigate the contribution of apoptosis to neutrophil dysfunction in uremia. Neutrophils harvested from uremic patients (n = 6) and age-/gender-matched healthy control subjects (n = 6) were incubated with either 50% autologous plasma or 10% fetal calf serum. After 24-h incubation, apoptosis was quantified by flow cytometry by using propidium iodide nuclear staining. Neutrophils from healthy volunteers were also incubated with either 50% heterologous normal or uremic plasma. After 24-h incubation, apoptosis was quantified by flow cytometry and transmission electron microscopy. In addition, superoxide production was determined by measuring the capacity to reduce ferri- to ferro-cytochrome C by using 4-beta-phorbol 12-beta-myristate 13-alpha-acetate or N-formyl methionyl-leucyl-phenylalanine (fMLP) for stimulus. Phagocytosis was determined by the uptake of 14C-labeled heat-killed Staphylococcus aureus. Compared with normal neutrophils, uremic neutrophils demonstrated greater apoptosis in the presence of autologous plasma (9 +/- 4 versus 19 +/- 6%, P = 0.01) as well as 10% fetal calf serum (19 +/- 7 versus 31 +/- 6%, P = 0.03). Furthermore, compared with normal neutrophils exposed to heterologous normal plasma, those exposed to heterologous uremic plasma exhibited higher apoptosis rates (19 +/- 3 versus 40 +/- 5%, P = 0.002), lower tMLP-stimulated superoxide production (22.6 +/- 2.5 versus 15.5 +/- 1.1 nmol O2*-/3.12 x 10(5) cells/30 min, P = 0.01), and a lower phagocytosis index (38 +/- 3% versus 27 +/- 5%, P = 0.04). Apoptosis correlated inversely with fMLP-stimulated superoxide production (r = -0.60, P = 0.04) and phagocytosis (r = -0.57, P = 0.05). These results suggest that uremic neutrophils undergo accelerated in vitro apoptosis. Furthermore, uremic plasma accelerates apoptosis of normal neutrophils, resulting in a dysfunctional pattern that is similar to that observed in uremia.

Early detection of peritonitis in continuous ambulatory peritoneal dialysis patients by use of chemiluminescence: evaluation of diagnostic accuracy by receiver-operating characteristic curve analysis

Continuous ambulatory peritoneal dialysis (CAPD) is now a widely accepted treatment for end-stage renal disease. However, the high incidence of peritonitis is a major complication of CAPD. Polymorphonuclear leukocytes (PMNs) play a major role in antimicrobial response of the host. During phagocytosis, the PMNs undergo a striking increase in oxidative metabolism, known as the respiratory burst, and emit light as chemiluminescence (CL). CL is thus a sensitive measure of PMN oxidative potential and correlates well with antimicrobial activity. In view of the observation of increased susceptibility to infection in CAPD patients, we have studied lucigenin- and luminol-enhanced CL in peritoneal fluids of these patients and assessed the diagnostic accuracy of these tests by ROC curve analysis. ROC curves showed diagnostic accuracies for both tests that were superior to counts of PMNs in the dialysis fluid (P &lt;0.001). At selected cutoff values of 150 000 cpm/vial for lucigenin CL and 600 000 cpm/vial for luminol CL, sensitivities were 100%. Specificities for lucigenin and luminol CL were 89% and 80%, respectively. Our results suggest that CL measurements can be used as an early marker for the presence of infection in CAPD patients.

Protective effects of grape seed proanthocyanidins and selected antioxidants against TPA-induced hepatic and brain lipid peroxidation and DNA fragmentation, and peritoneal macrophage activation in mice

1. The comparative protective abilities of a grape seed proanthocyanidin extract (GSPE) (25-100 mg/kg), vitamin C (100 mg/kg), vitamin E succinate (VES) (100 mg/kg) and beta-carotene (50 mg/kg) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation and DNA fragmentation in the hepatic and brain tissues, as well as production of reactive oxygen species by peritoneal macrophages, were assessed. 2. Treatment of mice with GSPE (100 mg/kg), vitamin C, VES and beta-carotene decreased TPA-induced production of reactive oxygen species, as evidenced by decreases in the chemiluminescence response in peritoneal macrophages by approximately 70%, 18%, 47% and 16%, respectively, and cytochrome c reduction by approximately 65%, 15%, 37% and 19%, respectively, compared with controls. 3. GSPE, vitamin C, VES and beta-carotene decreased TPA-induced DNA fragmentation by approximately 47%, 10%, 30% and 11%, respectively, in the hepatic tissues, and 50%, 14%, 31% and 11%, respectively, in the brain tissues, at the doses that were used. Similar results were observed with respect to lipid peroxidation in hepatic mitochondria and microsomes and in brain homogenates. 4. GSPE exhibited a dose-dependent inhibition of TPA-induced lipid peroxidation and DNA fragmentation in liver and brain, as well as a dose-dependent inhibition of TPA-induced reactive oxygen species production in peritoneal macrophages. 5. GSPE and other antioxidants provided significant protection against TPA-induced oxidative damage, with GSPE providing better protection than did other antioxidants at the doses that were employed.

Protective effects of zinc salts on TPA-induced hepatic and brain lipid peroxidation, glutathione depletion, DNA damage and peritoneal macrophage activation in mice

1. The comparative protective abilities of zinc L-methionine, zinc DL-methionine, zinc sulfate, zinc gluconate, L-methionine, DL-methionine, and vitamin E succinate (VES) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation, DNA fragmentation, and glutathione depletion in the hepatic and brain tissues, and production of reactive oxygen species by peritoneal macrophages were assessed. In addition, mice were fed a zinc-deficient diet for 5 weeks, and treated with TPA and/or zinc L-methionine or zinc DL-methionine, and similar studies were conducted. 2. The zinc-deficient diet induced oxidative stress in the hepatic and brain tissues as well as in the peritoneal macrophages as evidenced by significantly enhanced lipid peroxidation. DNA fragmentation, glutathione depletion, and production of reactive oxygen species. 3. Treatment of mice with zinc L-methionine, zinc DL-methionine, and VES decreased TPA-induced reactive oxygen species production as evidenced by significant decreases in chemiluminescence in peritoneal macrophages by approximately 45%, 31%, and 47%, respectively, and cytochrome c reduction by approximately 54%, 35%, and 41%, respectively, as compared with control values. Similar results were observed with liver and brain lipid peroxidation, DNA fragmentation, and glutathione depletion. 4. Zinc salts and antioxidants provided significant protection against TPA-induced oxidative damage. Zinc L-methionine provided the best protection.

Cyanate-mediated inhibition of neutrophil myeloperoxidase activity

Cyanate (CNO-) forms spontaneously in solutions containing urea, and is present in urine and the body fluids of uraemic patients. We have explored the possibility that CNO- might be one of the unknown substances responsible for the reported impairment, by urine and uraemic plasma, of neutrophil oxidative metabolism (especially as measured by luminol-enhanced chemiluminescence). Luminol-enhanced chemiluminescence generated by human neutrophils derives predominantly from the activity of myeloperoxidase (MPO) which produces hypochlorous acid from H2O2 and Cl-. We hypothesized that CNO- (which resembles the 'pseudohalide' thiocyanate, an alternative substrate for MPO) might somehow interfere with the activity of MPO. In support of this, we find: (i) CNO- inhibits both peroxidative and halogenating activities of MPO and also inhibits the enzyme within intact human neutrophils; (ii) the inhibition is H2O2-dependent, irreversible, accompanied by covalent addition of [14C]CNO- (or a carbon-containing fragment thereof) to the enzyme; (iii) CNO- also inhibits Cl-/H2O2/MPO-mediated bacterial killing. Impairment of this arm of neutrophil bactericidal activity by CNO- formed from urea may be one factor in the risk of urinary-tract infection associated with urinary stasis and perhaps in the generalized increase in susceptibility to infection in uraemic patients.

Inhibitory factors of serum opsonic activity in serum from patients with chronic renal failure

We investigated the mechanism of impaired serum opsonic activity in patients suffering from chronic renal failure (CRF). Prehemodialysis pooled serum from CRF patients was fractionated using Sephadex G-50 gel chromatography, and the effects of the obtained fractions on serum opsonic activity were examined using luminol-dependent chemiluminescence responses. Number 25-30 fractions in the prehemodialysis serum contained factors that may inhibit serum opsonic activity. The presumed molecular weight of these fractions is between 300 and 2800 daltons. These findings indicate that the inhibitory factors of serum opsonic activity may belong to middle molecules.

Comparative in vitro oxygen radical scavenging ability of zinc methionine and selected zinc salts and antioxidants

1. The concentration-dependent scavenging abilities of zinc DL-methionine, zinc sulfate, zinc gluconate, zinc picolinate and selected free radical scavengers, including superoxide dismutase (SOD), catalase, mannitol, allopurinol and DL-methionine, were examined against biochemically generated superoxide anion, hydroxyl radical and hypochlorite radical plus hypochlorous acid, by chemiluminescence and cytochrome c reduction. 2. Zinc methionine was the most effective of the zinc compounds that were tested. Following incubations with superoxide anion, hydroxyl radical, and hypochlorite radical-generating systems, in the presence of 50 microM zinc DL-methionine approximately 38%, 47% and 28% inhibition in reactive oxygen species generation was observed, respectively, compared to control groups. 3. The protective abilities of various zinc salts, as well as selected free radical scavengers and antioxidants were also assessed on phorbol ester (TPA)-induced lactate dehydrogenase (LDH) release from cultured PC-12 cells. Preincubation showed better protection than coincubation. Approximately 45% and 50% inhibition in TPA-induced LDH leakage was observed following preincubation with 50 microM zinc DL-methionine and 50 microM vitamin E succinate, respectively. Zinc DL-methionine exhibited better protection against LDH leakage than any other zinc salt tested. 4. The results indicate that zinc DL-methionine can attenuate the biochemical consequences of oxygen free radicals, and is comparable to other well-known antioxidants and free radical scavengers in the in vitro system that was employed.

Production of reactive oxygen species by gastric cells in association with Helicobacter pylori

Reactive oxygen species (ROS) and Helicobacter pylori have been identified as pathogenic factors in several gastrointestinal disorders. Since little information is available regarding the mechanistic pathways of H. pylori-induced gastric injury, the potential role of ROS was investigated. The induction of ROS in gastric cells (GC) by H. pylori was assessed using chemiluminescence, cytochrome c reduction, nitrobluetetrazolium (NBT) reduction and lactate dehydrogenase (LDH) leakage. The dose-dependent protective abilities of selected ROS scavengers on LDH leakage were determined. Following incubation of GC with three strains of H. pylori (1:1), approximately 5.7-8.0 and 3.8-4.3 fold increases were observed in cytochrome c and NBT reduction, respectively, demonstrating production of ROS. Enhanced chemiluminescence responses of 2.1- and 3.7-fold were observed following incubation of GC with H. pylori (ATCC 43504) at ratios of 1:1 and 1:10, respectively. Approximately 2.2- and 3.5-fold increases in LDH leakage were observed at GC:H. pylori (ATCC 43504) ratios of 1:1 and 1:10, respectively. Substantial inhibition of LDH leakage from GC in the presence of H. pylori was observed following co-incubations with selected ROS scavengers with cimetidine serving as the best chemoprotectant. The antioxidants and H2-receptor antagonists had no effect on growth of H. pylori cells. This study demonstrates that H. pylori induces enhanced production of ROS in GC, and enhances membrane damage.

Detection of oxidants in uremic plasma by electron spin resonance spectroscopy

Depletion of antioxidants and the presence of products of free radical damage in plasma suggest that oxidative stress is increased in uremia. We have developed an application of electron spin resonance spectroscopy, and used this method to show that a stable oxidizing component or components of plasma accumulate in uremia. No oxidizing activity was detectable in plasma from subjects with normal renal function. The oxidant was detected by its capacity to oxidize the spin trap 3,5-dibromo-4-nitrosobenzene sulphonate (DBNBS). The oxidant was dialyzable from plasma, had an upper molecular weight limit of about 3,000 Daltons and was stable over many months. Physiological plasma concentrations of vitamin C, a water soluble congener of vitamin E and reduced glutathione were unable to inhibit the oxidizing capacity of uremic plasma. Thus, uremia is associated with accumulation of an endogenous oxidizing activity at much higher concentrations than in subjects with normal renal function.

Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats

Chromium and its salts induce cytotoxicity and mutagenesis, and vitamin E has been reported to attenuate chromate-induced cytotoxicity. These observations suggest that chromium produces reactive oxygen species which may mediate many of the untoward effects of chromium. We have therefore examined and compared the effects of Cr(III) (chromium chloride hexahydrate) and Cr(VI) (sodium dichromate) following single oral doses (0.50 LD50) on the production of reactive oxygen species by peritoneal macrophages, and hepatic mitochondria and microsomes in rats. The effects of Cr(III) and Cr(VI) on hepatic mitochondrial and microsomal lipid peroxidation and enhanced excretion of urinary lipid metabolites as well as the incidence of hepatic nuclear DNA damage and nitric oxide (NO) production were also examined. Increases in lipid peroxidation of 1.8- and 2.2-fold occurred in hepatic mitochondria and microsomes, respectively, 48 hr after the oral administration of 25 mg Cr(VI)/kg, while increases of 1.2- and 1.4-fold, respectively, were observed after 895 mg Cr(III)/kg. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) were determined at 0-96 hr after Cr administration. Between 48 and 72 hr post-treatment, maximal excretion of the four urinary lipid metabolites was observed with increases of 1.5- to 5.4-fold in Cr(VI) treated rats. Peritoneal macrophages from Cr(VI) treated animals 48 hr after treatment resulted in 1.4- and 3.6-fold increases in chemiluminescence and iodonitrotetrazolium reduction, indicating enhanced production of superoxide anion, while macrophages from Cr(III) treated animals showed negligible increases. Increases in DNA single strand breaks of 1.7-fold and 1.5-fold were observed following administration of Cr(VI) and Cr(III), respectively, at 48 hr post-treatment. Enhanced production of NO by peritoneal exudate cells (primarily macrophages) was monitored following Cr(VI) administration at both 24 and 48 hr post-treatment with enhanced production of NO being observed at both timepoints. The results indicate that both Cr(VI) and Cr(III) induce an oxidative stress at equitoxic doses, while Cr(VI) induces greater oxidative stress in rats as compared with Cr(III) treated animals.

Hematologic aspects of end-stage renal failure

Renal dysfunction may give rise to a variety of hematologic disturbances, including anemia, leukocyte dysfunction, and coagulopathy. The anemia of renal failure has been attributed to a relative deficiency of erythropoietin, but absolute deficiencies of iron or folate may also play a role. Other contributing factors include heavy-metal toxicity, blood loss, and a reduction in red cell survival induced by toxic radicals. The treatment of the anemia of renal disease has advanced with the development of recombinant human erythropoietin. At subcutaneous doses of 50-75 IU/kg triweekly in selected patients, normalization of hemoglobin is presently possible. The coagulopathy of renal disease consists of an acquired qualitative platelet defect, best remedied by dialysis but also treated successfully by rHuEPO, cryoprecipitate or DDAVP, and conjugated estrogens. Uremia-induced leukocyte dysfunctions include diminished granulocyte chemotaxis, phagocytosis, and bactericidal activity. Cell-mediated immune defects and hypogammaglobulinemia have also been described. The pathophysiology of the hematologic manifestations of uremia is discussed. Therapeutic recommendations for dealing with anemia, bleeding, and infectious complications of renal failure are described.

Suppressive effect of sera from patients undergoing chronic hemodialysis on neutrophil chemiluminescence response

To determine the mechanism of easy infectability of uremic patients, we studied the effect of sera from uremic patients who were undergoing chronic hemodialysis on the chemiluminescence (CL) response of polymorphonuclear leukocytes (PMN). The luminol-dependent CL response was examined following stimulation with phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (FMLP). The patient's sera suppressed the CL response following stimulation by PMA, but not by FMLP. These findings suggest that sera from uremic patients undergoing hemodialysis contain a suppressive substance that suppresses the activation of PMNs by PMA.

Oxygen saturation during hemodialysis

The aim of this study was to examine the saturation patterns of cuprofane and polysulfone membranes in hemodialysis patients, and to correlate that with permeability of the alveolar membrane, unloading of CO2 over the membranes, and production of oxygen free radicals. Polysulfone membranes did not have the same desaturation pattern as the cuprofane membranes. Both membranes were equally effective in the unloading of CO2, and so alveolar hypoventilation does not explain oxygen desaturation during hemodialysis. White blood cells have a central role in the parallel development of early leucopenia and hypoxemia. The precise mechanism is still unknown because there were no changes in permeability of the alveolar membrane or production of oxygen free radicals.

Plasma tumor necrosis factor soluble receptors in chronic renal failure

Two soluble tumor necrosis factor receptors (sTNFRs) were detected in the plasma of patients with different degrees of chronic renal failure (CRF) and of long-term hemodialysis (HD) patients. In uremic undialyzed patients, plasma levels of both sTNFRs increased progressively with declining renal function. A linear correlation was found between sTNFR plasma levels and plasma creatinine concentration. sTNFR levels in end-stage uremic patients shortly before commencement of first HD treatment were approximately tenfold higher than in normal subjects. Long-term HD patients showed a further increase in plasma sTNFRs. The origin of sTNFRs, as well as their physiological role remains to be elucidated.

Effects of cefodizime on non-specific immune functions in patients with multiple myeloma

The effects of cefodizime (CDZ) on non-specific immunity in patients with multiple myeloma were studied in a randomized, placebo-controlled trial. A total of 51 patients with newly diagnosed multiple myeloma were admitted to the study, 27 of whom received CDZ 2 gi.v. once daily for seven days and 24 ascorbic acid 1 g daily i.v. for one week. Granulocyte chemotaxis, neutrophil biochemiluminescence and phagocytosis were determined at baseline, and at 48 h after the last dose. At baseline, chemiluminescence, phagocytosis and, to a lesser extent, granulocyte chemotaxis were diminished in both patient groups compared to healthy volunteers. After treatment, a significant increase in chemiluminescence and phagocytosis was observed in the CDZ group, while a slight increase in granulocyte chemotaxis did not reach statistical significance. No changes were observed in the control group. It is concluded that CDZ enhanced non-specific immune mechanisms in patients with multiple myeloma.

In vivo effect of 1,25-dihydroxyvitamin D3 on phagocyte function in hemodialysis patients

1,25-dihydroxyvitamin D3 [1,25(OH)2D3] has been shown to modulate the immune function of monocytes and macrophages. Patients with end-stage renal disease (ESRD) on chronic hemodialysis treatment usually present a deficiency of this active form of vitamin D3. The aim of this study was to investigate the effect of 1,25(OH)2D3 replacement therapy on phagocytosis, bactericidal capacity, and oxidative metabolism of peripheral blood polymorphonuclear leukocytes (PMNL) and monocytes (MN) in chronic hemodialysis patients. Phagocyte function tests were performed before and after four weeks of an oral replacement therapy with 0.5 micrograms/day of 1,25(OH)2D3 (Rocaltrol). The superoxide (O2-) generation of monocytes, measured by cytochrome c reduction and lucigenin-enhanced chemiluminescence (CL) from patients receiving hemodialysis treatment was significantly diminished compared to healthy controls. After the replacement therapy with 1,25(OH)2D3 the O2- production showed a significant improvement, resulting in an increased cytochrome c reduction and lucigenin-CL response. The bactericidal capacity of MN was also impaired and exhibited a significant enhancement of their killing activity after the administration of 1,25(OH)2D3. On the other hand, the luminol-enhanced CL, which reflects the myeloperoxidase-dependent oxidative metabolism, and the phagocytic ability of MN was not affected by the hormone. The function of polymorphonuclear leukocytes (PMNL) from hemodialysis patients showed no impairment in the state of 1,25(OH)2D3 deficiency and the replacement of the hormone did not enhance their function. These results suggest that the deficiency of 1,25(OH)2D3 in patients with ESRD on chronic hemodialysis treatment may be responsible for an impaired monocyte function, which could be improved by an in vivo replacement of the hormone.

Structural modifications of human beta 2 microglobulin treated with oxygen-derived radicals

Treatment of human beta 2 microglobulin (beta 2m) with defined oxygen-derived species generated by treatment with gamma-radiation was studied. As assessed by SDS/PAGE, the hydroxyl radicals (.OH) caused the disappearance of the protein band at 12 kDa that represents beta 2m, and cross-linked the protein into protein bands stable to both SDS and reducing conditions. However, when .OH was generated under oxygen in equimolar combination with the superoxide anion radical (O2.-), the high-molecular-mass protein products were less represented, and fragmented derivatives were not obviously detectable. Exposure to .OH alone, or to .OH + O2.- in the presence of O2, induced the formation of beta 2m protein derivatives with a more acidic net electrical charge than the parent molecule. In contrast, O2.- alone had virtually no effect on molecular mass or pI. Changes in u.v. fluorescence during .OH attack indicated changes in conformation, as confirmed by c.d. spectrometry. A high concentration of radicals caused the disappearance of the beta-pleated sheet structure and the formation of a random coil structure. Loss of tryptophan and significant production of dityrosine (2,2'-biphenol type) were noted, exhibiting a clear dose-dependence with .OH alone or with .OH + O2.-. The combination of .OH + O2.- induced a pattern of changes similar to that with .OH alone, but more extensive for c.d. and tryptophan oxidation (2 Trp/beta 2m molecule), and more limited for dityrosine formation. Lower levels of these oxidative agents caused the reproducible formation of species at 18 and 25 kDa which were recognized by antibodies against native beta 2m. These findings provide a model for the protein pattern observed in beta 2m amyloidosis described in the literature.

Glomerular basement membrane degradation by endogenous cysteine proteinases in isolated rat glomeruli

Recent in vitro and in vivo studies suggest that cysteine proteinases may play an important role in degradation of the glomerular basement membrane (GBM) by renal glomeruli. However, little information is available concerning the cysteine proteinases present in glomeruli, the distribution of cysteine proteinases in other areas of the kidney, or the potential role of endogenous glomerular cysteine proteinases in GBM degradation. Using well characterized fluorogenic substrates, we have documented the presence of the cysteine proteinases, cathepsins B, H, and L, in glomeruli (0.45 +/- 0.06, 0.39 +/- 0.05, and 0.66 +/- 0.14 mU/mg protein, mean +/- SEM, N = 8) and other fractions prepared from normal rat kidney. The presence of cysteine proteinases in glomeruli was verified by fluorescence microscopy. For each proteinase, the activity was: proportional to the amount of tissue protein and time of incubation; dependent on the presence of exogenously added dithiothreitol; and completely inhibited by the specific cysteine proteinase inhibitor, E-64. The pH optimum for cathepsin B (substrate: Z-Arg-Arg-HNMec) and L (substrate: Z-Phe-Arg-HNMec in the presence of Z-Phe-Phe-CHN2) was approximately pH 6.0 for both glomeruli and renal cortex; while that for cathepsin H (substrate: Arg-HNMec) was approximately 6.5. Incubation of sonicated glomeruli with 3H-GBM under conditions optimal for cysteine proteinase activity (pH 4.5, 1 mM EDTA, and 1 mM dithiothreitol, 37 degrees C) resulted in significant GBM degradation as measured by the release of non-sedimentable (10,000 x g, 10 min) radioactivity or hydroxyproline.(ABSTRACT TRUNCATED AT 250 WORDS)

Physicochemical characterization of a polypeptide present in uremic serum that inhibits the biological activity of polymorphonuclear cells

A granulocyte inhibitory protein was isolated and characterized from uremic serum by using ion-exchange column chromatography, high-performance size-exclusion chromatography, and immunochemical procedures. The purification process concentrated the protein 240-fold and to a purity of greater than 95%. An overall recovery of 45% was achieved; the purified protein had a specific activity of 104 units per mg of protein. The polypeptide had a molecular weight of approximately 28,000 and an isoelectric point of 4.0-4.5. Amino acid sequencing of the NH2 terminus revealed a single sequence (Asp-Ile-Val-Met-Thr-Gln-Ser-Pro-Gly-Thr-Leu-Ser-Val-Ser-Pro-Gly-Glu-Arg-Ala- Thr) that proved to be nonhomologous with other serum proteins that appear during an inflammatory state. The polypeptide inhibited the uptake of deoxyglucose, chemotaxis, oxidative metabolism, and intracellular bacterial killing by polymorphonuclear leukocytes. A specific rabbit polyclonal antibody raised against the protein nullified these inhibitory changes. We contend that the protein is responsible for the leukocyte dysfunction that is commonly seen in patients with uremia.

Evaluation of phagocytic cell function in an ex vivo model of hemodialysis

An ex vivo model of hemodialysis was used to evaluate the effect of dialysis membranes on phagocytic cell function. Blood was withdrawn continuously from healthy, non-uremic donors, heparinized, and pumped, single pass, through membrane modules under conditions which simulated normal dialysis conditions. The membrane modules contained membranes of cellulose, DEAE-substituted cellulose, or polysulfone. Blood was obtained from the module outlets for determination of complement activation, phagocyte elastase release, zymosan-induced phagocyte chemiluminescence, and monocyte interleukin-1 production. Significantly less complement activation occurred with the polysulfone and DEAE-substituted cellulose membranes than with cellulose membranes. Normal monocyte interleukin-1 production was not stimulated by any of the membranes used. In contrast, the cellulosic, but not the polysulfone, membranes primed the oxidative burst of the phagocytes and caused them to release elastase. DEAE-substituted cellulose had a lesser effect on elastase release than did cellulose and elastase release correlated significantly with the degree of complement activation. However, the correlation between complement activation and priming of phagocyte oxidative burst was weak, suggesting that membranes affect phagocyte oxidative metabolism through more than one mechanism. We conclude that some dialysis membranes stimulate the bacteriacidal functions of normal phagocytic cells, in part through complement-dependent mechanisms.

Transcription, not synthesis, of interleukin-1 and tumor necrosis factor by complement

Stimulation of interleukin-1 beta (IL-1 beta) and tumor necrosis factor (TNF alpha) production was studied during in vitro hemodialysis (HD) of whole blood using cuprammonium (Cup) or polysulfone (PS) dialyzers. In the absence of LPS, circulation of whole blood for two hours through Cup or PS dialyzers was not sufficient to induce production of IL-1 beta or TNF alpha in peripheral blood mononuclear cells (PBMC) during subsequent 24 hour culture. However, compared to freshly isolated cells, post-HD PBMC were primed to produce more IL-1 beta and TNF alpha when subsequently stimulated with LPS. Despite the lack of spontaneous monokine synthesis after HD, we observed transcription of mRNA coding for IL-1 beta and TNF alpha after two hours of LPS-free HD. When compared to levels of mRNA induced by 5 ng/ml LPS (100%), Cup induced 27 +/- 6% whereas PS did not induce detectable transcription of IL-1 beta. In the case of TNF alpha mRNA, Cup induced 26 +/- 8% and PS 13 +/- 3%. Recombinant C5a induced mRNA for IL-1 beta in PBMC without detectable IL-1 beta protein synthesis. We conclude that transcription of mRNA for IL-1 beta and TNF alpha during HD is primarily caused by complement activation by Cup, but that LPS or other factors are required for translation of IL-1 beta and TNF alpha mRNA transcribed during HD.

Antioxidant enzymes and lipoperoxide in blood in uremic children and adolescents

To determine whether oxidant-antioxidant balance is altered in chronic renal failure, antioxidant enzymes and lipid peroxide in peripheral blood cells and lipid peroxide in plasma were measured. Nine children and adolescents maintained on hemodialysis (HD), 9 on continuous ambulatory peritoneal dialysis (CAPD), and 14 controls were studied. Lipid peroxide was assayed fluorimetrically as thiobarbituric acid-reactive substances, superoxide dismutases by radioimmunoassays. Both manganese and copper-zinc superoxide dismutases in lymphocytes and monocytes in the HD and CAPD patients, and manganese superoxide dismutase in polymorphs in the HD patients were higher than in the controls. Copper-zinc superoxide dismutase, glutathione peroxidase, and catalase in erythrocytes were unaltered. The lipid peroxide level in plasma in the dialyzed patients was increased, whereas those in polymorphs and lymphocytes were unaltered. Triglyceride and total cholesterol in plasma in the dialyzed patients were also increased. The plasma lipid peroxide in the patients correlated with the triglyceride and total cholesterol level. This is the first study in which manganese superoxide dismutase is measured in nucleated cells of the patients with chronic renal failure. The present results suggest that increased superoxide dismutases protect against oxidative stress induced by chronic renal failure in nucleated cells but in neither erythrocytes nor plasma.