Oxidative stress markers and C-reactive protein in end-stage renal failure patients on dialysis

Advanced glycosylation end products as metabolic predictors of systemic pro-inflammatory and prooxidant status in patients with end-stage renal disease

Controlling systemic proinflammatory and prooxidant effectors is essential for mitigating cardiovascular risk and mortality in patients with end-stage renal disease (ESRD). However, monitoring these processes is still challenging due to the high uncertainty about their determinants and predictors. Thus, we investigated the relationship between advanced glycosylation end products (AGE), proinflammatory and prooxidant effectors in ESRD patients undergoing hemodialysis (HD). In addition to nutritional profile and dialysis efficiency, AGE, cytokines, chemokines, C-reactive protein (CRP), total (TAC) and non-protein (npAC) antioxidant capacity, lipid and protein oxidation were analyzed in blood samples from 43 HD patients. AGE, CRP, cytokines, chemokines, protein carbonyl (PCn), and malondialdehyde (MDA) were upregulated, while TAC and npAC were down-regulated in HD patients compared to heath subjects. Dialysis efficiency, TAC and npAC were reduced, while leucocytes counting, pre- and post-HD urea, TNF, IL-6, IL-10, CCL-2, MIP-1β, PCn, and MDA were increased in patients with higher AGE accumulation compared to those with lower AGE levels. Serum levels of CRP, protein carbonyl, malondialdehyde, and all cytokines and chemokines analyzed were correlated with AGE circulating levels for patients with higher AGE accumulation. AGE was inversely correlated with IL-10, TAC and npAC in patients with higher AGE accumulation. AGE exhibited predictive value (determination coefficient) to explain CRP, cytokines, chemokines, PCN, MDA, TAC and npAC variability in patients with higher AGE levels. Taken together, our findings provide evidence that AGE accumulation is associated with important proinflammatory and prooxidant effectors in patients with ESRD undergoing hemodialysis. Thus, AGE monitoring may be relevant to predict systemic inflammatory stress and the balance between oxidant and antioxidant status in these patients.

The neutrophil-to-lymphocyte ratio may indicate when to start hemodialysis

We evaluated whether the neutrophil-to-lymphocyte ratio (NLR) could aid dialysis decision-making in combination with the clinical presentation and biochemical findings. We retrospectively evaluated the medical records of 279 patients who commenced chronic maintenance hemodialysis. We compared the laboratory findings at 6 months before dialysis to those at dialysis initiation. NLR cutoffs and risk factors for each of six uremic symptoms were determined. Mean age was 60.7 years and mean estimated glomerular filtration rate (eGFR) was 5.7 ± 2.5 mL/min/1.73 m² at the time of hemodialysis and 7.7 ± 3.8 mL/min/1.73 m² 6 months earlier (p < 0.001). The mean NLR increased significantly from 2.5 ± 1.0 to 4.9 ± 2.8 (p < 0.001). The NLR was positively correlated with the C-reactive protein level (r = 0.202, p = 0.009) and negatively correlated with those of albumin (r = −0.192, p = 0.001) and total CO₂ (r = −0.134, p = 0.023). The NLR cutoffs for neurological and gastrointestinal symptoms as determined using receiver operator curve analysis were 2.4 (area under the curve [AUC] 0.976; 95% confidence interval [CI] 0.960–0.993; sensitivity 92.2%; specificity 94.7%) and 3.6 (AUC 0.671; 95% CI 0.588–0.755; sensitivity 68.1%; specificity 63.5%), respectively. On multiple linear regression analysis of neurological symptoms, the NLR was a significant predictor (β = −0.218, p = 0.017), as was age (β = 0.314, p = 0.037). In conclusion, the NLR may serve as a supplementary marker predicting uremic symptoms and a need for hemodialysis in stage 5 CKD patients.

Oxidative Stress Is Increased in Combined Oral Contraceptives Users and Is Positively Associated with High-Sensitivity C-Reactive Protein

Information concerning the mechanisms underlying oxidative stress and low-grade inflammation in young healthy women predisposing eventually to future diseases is scarce. We investigated the relationship of oxidative stress and high-sensitivity C-reactive protein (hsCRP) in fertile-age women by oral combined contraceptive (OC) use. Caucasian Italian healthy non-obese women (n = 290; 100 OC-users; 190 non-OC-users; mean age 23.2 ± 4.7 years) were analyzed. Blood hydroperoxides, as oxidative stress biomarkers, were assessed by Free Oxygen Radical Test (FORT). Serum hsCRP was determined by an ultra-sensitive method (hsCRP). Markedly elevated oxidative stress (≥400 FORT Units) was found in 77.0% of OC-users and 1.6% of non-OC-users, odds ratio (OR) = 209, 95% CI = 60.9–715.4, p < 0.001. Elevated hsCRP levels ≥ 2.0 mg/L, considered risky for cardiovascular diseases (CVDs), were found in 41.0% of OC-users and 9.5% of non-OC-users, OR = 6.6, 95%CI 3.5–12.4, p < 0.001. Hydroperoxides were strongly positively correlated to hsCRP in all women (r_s = 0.622, p < 0.001), in OC-users (r_s = 0.442, p < 0.001), and in non-OC-users (r_s = 0.426, p < 0.001). Women with hydroperoxides ≥ 400 FORT Units were eight times as likely to have hsCRP ≥ 2 mg/L. In non-OC-users only, hydroperoxides values were positively correlated with weight and body mass index, but negatively correlated with red meat, fish and chocolate consumption. Our research is the first finding a strong positive correlation of serum hydroperoxides with hsCRP, a marker of low-grade chronic inflammation, in young healthy women. Further research is needed to elucidate the potential role of these two biomarkers in OC-use associated side-effects, like thromboembolism and other CVDs.

Gastrointestinal bleeding in patients with renal failure under hemodialysis treatment: a single-center experience

PURPOSE

Gastrointestinal bleeding remains the leading cause of morbidity and mortality for patients who need hemodialysis treatment. Our aim was to evaluate patients who needed hemodialysis and presented with bleeding during their hospital stay (uremic bleeding patients). Factors that increased the risk of bleeding and death were evaluated. Additionally, uremic bleeding patients were compared to non-uremic bleeding patients regarding gastrointestinal findings.

PATIENTS AND METHODS

Fifty-one uremic bleeding patients were compared to two control groups which included uremic (hemodialysis dependent and non-bleeding) and non-uremic (no renal insufficiency and bleeding) patients.

RESULTS

NSAIDs and anti-ulcer drug usage were more common in uremic bleeding and in uremic non-bleeding groups, respectively. Dialysis vintage was longer in uremic bleeding group. Comparison of uremic bleeding and non-bleeding uremic patients regarding the usage of ACEI or ARB drugs yielded non-significant results. Acute kidney injury, lower plasma albumin level and high CRP level were significantly increased the risk of mortality in uremic bleeding patients. Hospital stay more than 1 week was the only strong factor for mortality when multivariate analysis was performed. Gastroduodenal and duodenal ulcers were significantly detected in uremic bleeding and non-uremic bleeding patients; respectively.

CONCLUSIONS

Hemodialysis patients presenting with gastrointestinal bleeding should be evaluated regarding use of prescriptions and efforts should be done in order to shorten their hospital stay and decrease their mortality. Effect of ACEI or ARB drugs should also be evaluated in future studies.

Relationship of Neutrophil-to-Lymphocyte Ratio and Serum Albumin Levels with C-Reactive Protein in Hemodialysis Patients: Results from 2 International Cohort Studies

BACKGROUND/AIM

The neutrophil-to-lymphocyte ratio (NLR), defined as the neutrophil count divided by lymphocyte count, is an inexpensive and readily available parameter, which may serve as a surrogate for inflammation markers, such as C-reactive protein (CRP). The aim of this study was to determine the utility of NLR in the prediction of elevated CRP levels in hemodialysis (HD) patients.

METHODS

We analyzed 43,272 HD patients from 2 distinct cohorts within the Monitoring Dialysis Outcomes research collaboration in whom contemporaneous measurements of neutrophil and lymphocyte counts, serum albumin and CRP levels were available. Logistic regression was used to determine the relationship of trichotomized NLR (<2.5, 2.5-5 and >5.0) and albumin levels (<3.1, 3.1-4.0 and >4.0 g/dl) with elevated CRP levels (>10.0, >20.0 and >30.0 mg/l). Congruence of the prediction models was examined by comparing the regression parameters and by cross-validating each regression equation within the other cohort.

RESULTS

We found that NLR >5.0 vs. <2.5 (cohort 1: OR 2.3; p < 0.0001 and cohort 2: OR 2.0; p < 0.0001) was associated with CRP levels >10.0 mg/l. Stepwise increase in odds ratio for CRP >10.0 mg/l was observed with the combination of high NLR and low albumin levels (NLR >5.0 and albumin <3.1) (cohort 1: OR 7.6; p < 0.0001 and cohort 2: OR 11.9; p < 0.0001). Cross-validation of the 2 regression models revealed a predictive accuracy of 0.68 and 0.69 in the respective cohorts.

CONCLUSION

This study suggests that NLR could serve as a potential surrogate marker for CRP. Our results may add to diagnostic abilities in settings where CRP is not measured routinely in HD patients. NLR is easy to integrate into daily practice and may be used as a marker of systemic inflammation.

Comparison of plasma oxidative biomarkers and conformational modifications of hemoglobin in patients with diabetes on hemodialysis

BACKGROUND

Diabetes is associated with an increased generation of reactive oxygen species (ROS), which plays an important role in the development of oxidative stress and anemia.

OBJECTIVES

The main purpose of this study was to investigate whether patients with diabetes undergoing hemodialysis (HD) were susceptible to oxidative stress and whether resulting damages affect the structure of hemoglobin (Hb) and plasma proteins.

PATIENTS AND METHODS

Twenty patients with diabetes undergoing HD, 20 patients with diabetes and normal renal function, and 20 age- and sex-matched healthy subjects were included in this study. Methaemoglobin (Met-Hb), hemichrome and conformational changes of Hb were analyzed as oxidative markers in erythrocytes. Ferric reducing ability of plasma (FRAP) and protein carbonyl content (PCO) were determined as plasma oxidative biomarkers. Also triglyceride, cholesterol, albumin, blood urea nitrogen (BUN), creatinine, glucose and uric acid were assayed as biochemical parameters of plasma.

RESULTS

Patients with diabetes undergoing hemodialysis had significantly lower levels of PCO and albumin (P < 0.05), but significantly higher levels of FRAP, BUN, creatinine and uric acid (P < 0.05) as compared to patients with diabetes and normal renal function. Linear regression analysis showed significant negative correlations between PCO and FRAP (r = -0.53), oxy-Hb (r = -0.88) and Hb absorbance at 340 nm (r = -0.79), 420 nm (r = -0.85) and 577 nm (r = -0.68) in patients with diabetes undergoing hemodialysis. Also PCO was significantly and positively correlated with Hb absorbance at 275 nm (r = 0.63) and 560 nm (r = 0.61) which confirmed the oxidative damage to erythrocytes in control subjects.

CONCLUSIONS

Hemodialysis exacerbates oxidative stress and conformational changes of Hb in patients with diabetes on hemodialysis. The FRAP value can be used as a positive determinant, while PCO and Hb derivatives can be used as negative determinants of oxidative stress in patients with diabetes.

Pilot validation of objective malnutrition-inflammation scores in pediatric and adolescent cohort on chronic maintenance dialysis

Background:

In recognition of the challenges inherent with the use of single-item indices for the diagnosis of malnutrition–inflammation morbidity in pediatric dialysis patients, to enhance accuracy, we validated a composite scoring system in a pilot study. The objective malnutrition—inflammation score seeks to validate the use of a composite scoring system as a tool for assessing malnutrition—inflammation burden in a pediatric dialysis population.

Methods:

We enrolled 20 patients on hemodialysis (n = 14) and peritoneal dialysis (n = 6) over a period of 12 months. We derived composite scores from selected indices of renal pathology, nutrition, dialysis adequacy, protein catabolism, and dialysis modality. We assessed reliability by a test–retest method and measured validity by defining the relationship of the indices with serum C-reactive protein in a multiple regression analysis. We calculated sensitivity, specificity, accuracy, and precision for the malnutrition—inflammation score.

Results:

The mean age was 12.8 years (standard deviation = 6.1), and male–female ratio was 12:8. Patients (n = 8) with elevated serum C-reactive protein (>0.3 mg/dL) had higher composite score for malnutrition—inflammation morbidity. Similarly, the pediatric cohort on hemodialysis had higher score than those on peritoneal dialysis. Upon reliability testing, a low value of typical error (0.07) and high correlation coefficient (r = 0.95) supported validity of the instrument. Moreover, multiple regression analysis showed a strong predictive relationship (R² = 0.9, p = 0.03) between the indices and serum C-reactive protein. Sensitivity of malnutrition—inflammation score was 62.5%, specificity was 83%, accuracy was 75%, and precision was 71%.

Conclusion:

Using criterion-validation method, we established the potential use of multi-diagnostic approach to quantify malnutrition—inflammation morbidity in a pediatric dialysis cohort. Given the small sample size, large-scale population-specific studies are needed to ratify these findings and to demonstrate its clinical effectiveness.

Associations between serum hepcidin level, FGF-21 level and oxidative stress with arterial stiffness in CAPD patients

BACKGROUND

Patients on continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis have accelerated atherosclerosis associated with an increase in cardiovascular morbidity and mortality. Atherosclerosis is associated with increased arterial stiffness (AS), endothelial dysfunction and elevated oxidative stress (OS) and inflammation. We aimed to investigate the relationship between oxidative stress status, arterial stiffness, hepcidin and fibroblast growth factor-21 (FGF-21) levels in CAPD patients.

METHODS

As a prospective observational study, we analyzed 56 CAPD patients, aged between 30 and 63 years. Serum hepcidin, FGF-21 levels, OS status and AS were determined. Arterial stiffness was measured by flow-mediated dilatation (FMD). Oxidative stress status was determined by total antioxidant status, total oxidant status (TOS) and oxidative stress index (OSI).

RESULTS

FMD was negatively correlated with TOS, OSI, hepcidin and FGF-21 (r: -0.313, p: 0.020; r: -0.0331, p: 0.014; r: -0.498, p < 0.001; r: -0.403, p: 0.002, respectively). OSI was positively correlated with hepcidin, parathormone and negatively correlated with FMD (r: 0.278, p: 0.040; r: 0.462, p < 0.001; r: -0.0331, p: 0.014, respectively).

CONCLUSION

There are many factors affecting arterial stiffness in CAPD patients. In our study, higher levels of OS status, hepcidin and FGF-21 were independent determinants of arterial stiffness in PD patients. Therefore, definition and improvement of these new parameters will be helpful to reduce the cardiovascular disease risk and mortality in CAPD patients.

Different peptic ulcer bleeding risk in chronic kidney disease and end-stage renal disease patients receiving different dialysis

BACKGROUND

End stage renal disease (ESRD) patients receiving hemodialysis (HD) have a higher risk of peptic ulcer bleeding (PUB).

AIMS

Whether ESRD patients receiving peritoneal dialysis (PD) also carries a higher risk of PUB has not been studied.

METHODS

This was a cohort study using Taiwan's National Health Insurance research database, whereby 11,408 patients, including 2,239 PD, 2,328 HD, 2,267 chronic kidney disease (CKD) and 4,574 controls with age-sex matching were recruited. The log-rank test was used to analyze differences in accumulated PUB-free survival rates between groups. Cox proportional hazard regression was performed to evaluate independent risk factors for PUB in all the enrollees.

RESULTS

During the 7-year follow-up, PD and CKD patients had a significantly higher rate of PUB than matched controls. The risk of PUB between PD and CKD was not significantly different. Moreover, patients receiving HD carried a higher risk of PUB than those receiving PD, with CKD and controls (p all <0.05, by log-rank test). Cox proportional hazard regression analysis showed that CKD (HR 3.99, 95 % CI 2.24-7.13), PD (HR 3.71, 95 % CI 2.00-6.87) and HD (HR 11.96, 95 % CI 7.04-20.31) were independently associated with an increased risk of PUB. Being elderly, male, having hypertension, diabetes, cirrhosis, and nonsteroidal anti-inflammatory drugs and steroid use were other independent risk factors of PUB in all enrollees.

CONCLUSIONS

Patients with CKD and ESRD receiving PD or HD carried a higher risk for PUB. They should be screened for risk factors for PUB and receive some protective measures to prevent PUB.

Nonpeptic ulcer, nonvariceal gastrointestinal bleeding in hemodialysis patients

OBJECTIVES

Hemodialysis patients carry a higher risk of peptic ulcer bleeding. Whether hemodialysis patients also have a higher occurrence of nonpeptic ulcer, nonvariceal gastrointestinal bleeding needs further evaluation.

METHODS

Using Taiwan's National Health Insurance research database, the occurrence of nonpeptic ulcer, nonvariceal gastrointestinal bleeding was compared among the hemodialysis patients, chronic kidney disease patients, and controls using log-rank test. Risk factors were identified by Cox regression analysis.

RESULTS

A total of 20,830 patients were enrolled, including 8210 hemodialysis and 4190 chronic kidney disease patients and 8430 age- and sex-matched controls in a 2:1:2 ratio. In the 7-year follow-up period, hemodialysis patients had a significantly higher cumulative hazard of nonpeptic ulcer, nonvariceal gastrointestinal bleeding than chronic kidney disease patients and controls (P <.001, by log-rank test). The hazard also was significantly higher in the chronic kidney disease patients than in controls. Cox regression analysis revealed that older age, the comorbidities of diabetes mellitus, cirrhosis, and chronic obstructive pulmonary disease, history of uncomplicated peptic ulcer disease, chronic kidney disease (hazard ratio 5.17), hemodialysis (hazard ratio 9.43), and use of selective serotonin reuptake inhibitors were independent risk factors for nonpeptic ulcer, nonvariceal gastrointestinal bleeding in all study patients. Old age, diabetes mellitus, cirrhosis, chronic obstructive pulmonary disease, history of uncomplicated peptic ulcer disease, and use of selective serotonin reuptake inhibitors were independent risk factors in hemodialysis patients.

CONCLUSIONS

There is a higher risk of developing nonpeptic ulcer, nonvariceal gastrointestinal bleeding in hemodialysis patients after adjustments for age, sex, underlying comorbidities, and ulcerogenic medication. The risk has increased since patients had chronic kidney disease.

Defected red blood cell membranes and direct correlation with the uraemic milieu: the connection with the decreased red blood cell lifespan observed in haemodialysis patients

Together with impaired production of erythropoietin and iron deficiency, the decreased lifespan of red blood cells (RBCs) is a main factor contributing to the chronic anaemia observed in haemodialysis (HD) patients. Atomic force microscopy is employed in this work to thoroughly survey the membrane of intact RBCs (iRBCs) of HD patients in comparison to those of healthy donors, aiming to obtain direct information on the structural status of RBCs that can be related to their decreased lifespan. We observed that the iRBC membrane of the HD patients is overpopulated with extended circular defects, termed 'orifices', that have typical dimension ranging between 0.2 and 1.0 μm. The 'orifice' index-that is, the mean population of 'orifices' per top membrane surface-exhibits a pronounced relative increase of order 54 ± 12% for the HD patients as compared to healthy donors. Interestingly, for the HD patients, the 'orifice' index, which relates to the structural status of the RBC membrane, correlates strongly with urea concentration, which is a basic index of the uraemic milieu. Thus, these results indicate that the uraemic milieu downgrades the structural status of the RBC membrane, possibly triggering biochemical processes that result in their premature elimination from the circulation. This process could decrease the lifespan of RBCs, as observed in HD patients.

Green Tea Attenuates Oxidative Stress and Downregulates the Expression of Angiotensin II AT(1) Receptor in Renal and Hepatic Tissues of Streptozotocin-Induced Diabetic Rats

This study investigates the potential of green tea to modulate oxidative stress and angiotensin II AT₁ receptor expression in renal and hepatic tissues of diabetic rats. Three groups of rats were studied after 8 weeks following diabetes induction: normal, streptozotocin-induced diabetic (diabetic control), and green-tea-treated diabetic rats. Total antioxidant, catalase, and malondialdehyde levels were assayed by standard procedures. Levels of AT₁ receptor labeling, in renal and hepatic tissues of the three rat groups, were immunohistochemically investigated using an anti-AT₁ receptor antibody. Levels of total antioxidant and catalase were significantly reduced, whereas malondialdehyde levels and AT₁ receptor labeling were significantly increased in renal and hepatic tissues of diabetic control rats compared to normal rats. Compared to diabetic control rats, total antioxidant and catalase levels were significantly increased, whereas malondialdehyde levels and AT₁ receptor labeling in the green-tea-treated diabetic group were significantly reduced throughout hepatic lobules and renal cortical and medullary vascular and tubular segments to levels comparable to those observed in normal rats. The capacity of green tea to modulate diabetes-induced oxidative stress and AT₁ receptor upregulation may be beneficial in opposing the deleterious effects of excessive angiotensin II signaling, manifested by progressive renal and hepatic tissue damage.

Association between vitamin C deficiency and dialysis modalities

AIM

  We designed a cross-sectional study to investigate plasma vitamin C level in patients who underwent maintenance haemodialysis (MHD) and continuous ambulatory peritoneal dialysis (CAPD) to explore whether there is a difference in vitamin C deficiency between MHD patients and CAPD patients.

METHODS

  This investigation included 382 dialysis patients without vitamin C supplement before the study. Demographic characteristics, laboratory tests, ascorbic acid and total plasma vitamin C level were measured. A linear regression model was built to explore the association between vitamin C deficiency and dialysis modalities after adjusting for age, dialysis vintage, gender, Charlson index, modality of dialysis and hsCRP.

RESULTS

  The range of plasma vitamin C level was from 0.48 µg/mL to 31.16 µg/mL. 35.9% (n = 137) patients had severe vitamin C deficiency (<2 µg/mL). Plasma vitamin C level was inversely associated with age and dialysis vintage. After age and dialysis vintage were adjusted, vitamin C deficiency was associated with MHD. R square for model fitting was relatively low, which implied that there were other vitamin C influencing factors not included in the model.

CONCLUSIONS

  Vitamin C deficiency is common in dialysis patients, especially in patients treated with MHD.

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.

Does dialysis modality influence the oxidative stress of uremic patients?

BACKGROUND/AIMS

Since peritoneal membrane is more compatible and residual renal function better preserved during peritoneal dialysis, we questioned whether the oxidative burden in chronic kidney disease (CKD) is influenced by dialysis modality.

METHODS

49 stable CKD patients, 17 on continuous ambulatory peritoneal dialysis (CAPD), 16 on hemodialysis (HD), and 16 non-dialyzed, and 13 healthy subjects were enrolled. Plasma thiobarbituric acid-reactive substances (TBARS; nmol/g protein), serum total antioxidant activity (TAA), total plasma-free thiols (Pt-SH; μmol/g protein), albumin and uric acid were measured by spectrophotometry. Serum residual antioxidant activity (RAA) was calculated.

RESULTS

TBARS were higher in HD (78.3 ± 20.3) versus both non-dialyzed (53.1 ± 27.9, p = 0.007) and CAPD groups (58.3 ± 19.8, p = 0.008). Pt-SH was reduced in CKD patients, but showed comparable values between dialysis groups. TAA and RAA were similarly increased in HD and CAPD patients than in the other two groups.

CONCLUSION

Oxidative stress occurs in all CKD patients and worsens as renal function declines. Lipid peroxidation seems more augmented during chronic HD as compared to CAPD, but the plasma antioxidant status did not differ between the investigated dialysis methods. Therefore, dialysis modality appears to influence lipid peroxidation without changing the extracellular antioxidant defense of CKD patients.

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.

Serum iron markers are inadequate for guiding iron repletion in chronic kidney disease

BACKGROUND AND OBJECTIVES

Iron (Fe) overload may complicate parenteral Fe therapy used to enhance the efficacy of erythropoietic-stimulating agents in the treatment of anemia of chronic kidney disease. However, serum Fe markers are influenced by inflammation or malignancy and may not accurately reflect the amount of body Fe.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied the relationship between parenteral Fe therapy, conventional serum Fe markers, and liver iron concentration (LIC) measured using magnetic resonance R2 relaxometry (FerriScan) in 25 Fe-deficient predialysis chronic kidney disease patients before and 2 and 12 weeks after single high-dose intravenous Fe and in 15 chronic hemodialysis patients with elevated serum ferritin (>500 μg/L).

RESULTS

In predialysis patients, there was strong dose dependency between the administered Fe dose and changes in LIC at weeks 2 and 12; however, no dose dependency between Fe dose and changes in ferritin or transferrin saturation (TSAT) were observed. In hemodialysis patients, LIC correlated with the cumulative Fe dose and duration of dialysis but not with current ferritin or TSAT. The cumulative Fe dose remained a significant independent predictor of LIC in a multiple regression model. Two dialysis patients who received >6 g parenteral Fe had substantially elevated LIC >130 μmol/g, which is associated with hemochromatosis.

CONCLUSIONS

In Fe-deficient predialysis patients, intravenous Fe therapy is associated with increases in LIC unrelated to changes in conventional Fe markers. In hemodialysis patients, TSAT and ferritin are poor indicators of body Fe load, and some patients have LICs similar to those found in hemochromatosis.

Linkage of some trace elements, peripheral blood lymphocytes, inflammation, and oxidative stress in patients undergoing either hemodialysis or peritoneal dialysis

BACKGROUND

Changes in essential trace elements may affect the inflammatory and immunological state of patients on hemodialysis (HD) or peritoneal dialysis (PD). Therefore, we aimed to determine trace element content and markers of oxidative stress, inflammation, and immune status in HD and PD patients and to assess the relationships among these parameters.

METHODS

Patients on either HD (n = 20) or PD (n = 20) and age-, sex-, body mass index-matched healthy individuals (n = 20) were enrolled in the study. The trace elements zinc, copper, selenium, and iron; markers of oxidative stress thiobarbituric acid reactive substances (TBARS) and protein carbonyl levels; activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase; percentages of CD3 T lymphocytes and the subsets CD4 and CD8; the CD4/CD8 ratio; and C-reactive protein (CRP) were measured.

RESULTS

All dialysis patients had low levels of albumin and hemoglobin. Significantly decreased percentages of CD3 and CD4 T lymphocytes and increased levels of CRP, TBARS, and carbonyl compounds were observed in HD patients. HD patients also had elevated erythrocyte SOD, lower GPx and catalase activities, and decreased levels of Se, Zn, and Fe in comparison to PD patients and healthy subjects. In addition, CRP was positively associated with TBARS and carbonyl levels, but was significantly inversely associated with Zn and Se levels. Positive correlations were found between T lymphocyte CD3 and CD4 percentages and Zn, Se, and Fe levels.

CONCLUSIONS

There were significant decreases in T lymphocyte-related immunological regulation and increased inflammation and oxidative stress in dialysis patients. Essential trace element status was independently related to immune status, inflammation, and oxidative damage.

Biochemistry and biomarkers of inflamed patients: why look, what to assess

Specific laboratory tests and physical findings are available to the practicing clinician that should raise the suspicion of inflammation. Inflammation is related to specific clinical outcomes. Once identified, changes in clinical practice may affect the level of inflammation in individual and or groups of dialysis patients with the hope that these changes may in turn affect outcome in a positive manner. Standard clinical tests and observations associated with inflammation are hypoalbuminemia, erythropoietin resistance, decreased iron saturation accompanied by high ferritin, frailty, low serum creatinine, reduced total and LDL-cholesterol, and increased C reactive protein (CRP). Inflammation is strongly associated with loss of physical function, dyslipidemia (low LDL- and HDL-cholesterol, increased triglycerides), and anemia that is unresponsive to erythropoietin. Inflammation is associated with cardiovascular events, increased hospitalization, and death. Correctible causes of inflammation are tunneled dialysis catheters, arteriovenous grafts, catheter infection, periodontal disease, poor water quality, and dialyzer incompatibility. Obesity also is a source of cytokines but may be less amenable to treatment. Inflammation is multifactorial in dialysis patients. Some sources are recognizable and correctable, such as vascular access type, clinical infection, and water quality, and some are not. Inflammation is strongly associated with outcome.

Physiological variables involved in heart valve substitute calcification

Biochemical, histological and genetic studies using in vitro/in vivo models have demonstrated that pathological calcification of bioprosthetic heart valves (BHV) is regulated by various mechanisms associated with physiological variables. The major objective of this review is to characterize physiological variables involved in BHV calcification. This review examines our understanding of the systemic cellular behavior and physiological regulation processes behind BHV calcification and its clinical applications.

Free and total plasma malondialdehyde in chronic renal insufficiency and in dialysis patients

BACKGROUND

Available data about oxidative status in patients with end-stage renal disease (ESRD) or on dialysis are contradictory. The present cross-sectional study aimed to investigate the role of renal insufficiency and dialysis on lipid peroxidation. To separate the effects of uraemia from dialysis-induced stress, we enrolled 26 patients with renal insufficiency on conservative treatment (ESRD), 23 on peritoneal dialysis (PD), 30 on haemodialysis (HD) and 30 controls.

METHODS

Plasma malondialdehyde (MDA) levels, both total (tMDA) and free (fMDA), were measured as indexes of oxidative stress by gas chromatography-mass spectrometry. Bound MDA (bMDA) levels were calculated as the difference between tMDA and fMDA.

RESULTS

Total and bMDA concentrations were significantly higher in patients than in controls (ESRD > HD > PD). In PD and HD patients, fMDA levels were similar and significantly higher than in ESRD. Multivariate analysis, with tMDA, fMDA and bMDA as dependent variables, showed similar and significant tMDA and bMDA relations with residual renal function (t = -2.160, P = 0.035) and albumin (t = -2.049, P = 0.045). Erythropoietin dose affected only fMDA values (t = -2.178, P = 0.034).

CONCLUSIONS

Free and bMDA concentrations identified different MDA patterns. Bound MDA, not excreted by kidneys, accounts alone for high tMDA concentrations in ESRD patients, while both fMDA and bMDA contribute to tMDA values in dialysis patients. These findings show that increased tMDA could be indicative not only of recent lipid peroxidation, and they also highlight the importance of evaluating free, bound and total MDA in patients with reduced renal function in order to assess their oxidative status.

Oxidative Stress and Inflammation in Chronic Kidney Disease: Role of Intravenous Iron and Vitamin D

Cardiovascular disease (CVD) is the leading cause of death among chronic kidney disease patients (CKD). The etiology of CVD in CKD is multifactorial and increasing evidence points to the important contribution of “nontraditional” risk factors including oxidative stress and inflammation. CKD is associated with a chronic imbalance of prooxidant and antioxidant factors that results in a state of chronic inflammation. Intravenous iron supplementation has been shown to induce oxidative stress and has been associated with lipid peroxidation and DNA damage. Conversely, treatment with vitamin D analogs has been associated with improved mortality in hemodialysis patients in 2 recent large cohort studies. These data suggest that vitamin D analogs may exert effects beyond their pharmacologic role in parathyroid hormone suppression. This article addresses the current data regarding the relative contributions of intravenous iron supplementation and vitamin D analog therapy on oxidative stress and inflammation in CKD patients.

Serum Concentrations of F2-Isoprostanes and 4-Hydroxynonenal in Hemodialysis Patients in Relation to Inflammation and Renal Anemia

Background

Patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD) are apparently exposed to enhanced oxidative stress and to inflammation. It was the aim of this study to characterize the state of systemic oxidative stress of ESRD patients before and following HD using highly specific biomarkers, F₂-isoprostanes and 4-hydroxynonenal (HNE). Furthermore the question should be answered, if there are associations between inflammation and systemic oxidative stress and/or between systemic oxidative stress and renal anemia, which is more or less typical for HD patients.

Patients and methods

Concentrations of F₂-isoprostanes, HNE, C-reactive protein (CRP) as marker of inflammation, and hemoglobin were measured in serum samples of patients with ESRD before and after HD and of healthy control persons for comparison. Total (esterified plus free) F₂-isoprostanes were quantified by highly sensitive gas chromatography/mass spectrometry technique, HNE by thin layer chromatography and HPLC/UV detection, CRP by immunoturbidimetry and hemoglobin by clinico-chemical routine assay.

Results

1. HD patients showed significantly higher serum concentrations of F₂-isoprostanes and HNE than healthy human control subjects. 2. Total (esterified plus free) F₂-isoprostane levels before HD were not significantly different from those after HD, whereas HNE levels were significantly decreased in patients after HD. 3. F₂-isoprostane concentrations in HD patients correlated with the levels of CRP, whereas HNE concentrations inversely correlated with the content of hemoglobin.

Conclusion

Both, F₂-isoprostanes and HNE serum concentrations are useful oxidative stress parameters in ESRD patients undergoing HD. Whereas HNE strongly correlates with the severity of renal anemia, leading to left heart insufficiency, F₂-isoprostanes (sum of free plus esterified) highly correlate with the degree of inflammation.

Oxidative Stress in Children on Peritoneal Dialysis

Objectives

Enhanced oxidative stress has been observed in dialysis and predialysis adult patients with chronic kidney disease (CKD), which resulted in increased mortality and morbidity within this population. Not much attention in the literature has been paid to nonenzymatic antioxidant defense in children with CKD on peritoneal dialysis (PD). The aim of the present study was to describe the plasma, erythrocyte, and dialysate concentrations of oxidized (GSSG) and reduced glutathione (GSH) and vitamins A, E, and C in a pediatric PD population.

Patients

10 children on PD and 27 age-matched healthy subjects were enrolled in the study.

Results

Erythrocyte and plasma GSH concentrations were lower in PD patients, erythrocyte concentration of GSSG remained unchanged, and plasma GSSG was significantly higher in children on PD. Children on PD exhibited decreased plasma concentrations of antioxidant vitamins compared to healthy subjects. Moreover, we documented loss of vitamins A, E, and C into ultrafiltrate.

Conclusion

Such low plasma levels of vitamins A, E, and C and simultaneously decreased activity of erythrocyte GSH may be responsible for the increased oxidative stress occurring in children with CKD on PD.

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.

In Renal Transplanted Patients Inflammation and Oxidative Stress Are Interrelated

INTRODUCTION

The inflammatory state plays a well-documented role to cause oxidative stress, especially in end-stage renal disease (ESRD) patients, wherein several cardiovascular risk factors are amplified by the coexistence of a microinflammatory state with increased oxidative stress.

METHODS

We measured serum concentrations of high sensitivity C-reactive protein (CRP), tumor necrosis factor alpha (TNFalpha), 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha-in vivo oxidative stress marker) in 15 chronic renal failure (CRF) and 15 transplant patients versus 15 healthy controls. Exclusion criteria were: age <30 or >65 years as well as a diagnosis of diabetes or cardiovascular diseases. We evaluated systolic (SBP) and diastolic blood pressure (DBP), serum creatinine (sCr), and glomerular filtration rate (GFR).

RESULTS

Both the transplanted and the CRF group showed significantly higher values of CRP, TNFalpha, and 8-iso-PGF2alpha than the controls (P < .05 for all). SBP, DBP, and sCr were not different between transplanted and CRF patients. CRP was higher in transplant recipients than in CRF patients (P < .05). No difference in TNFalpha levels was observed between the two groups. 8-iso-PGF2alpha was significantly higher in the CRF than in the transplanted group (P < .05), although the latter cohort showed a positive correlation between 8-iso-PGF2alpha and TNFalpha (P < .001), sCr (P < .001), SBP (P < .05), and DBP (P < .05). In the same group both 8-iso-PGF2alpha and TNFalpha were negatively correlated with GFR (r -.824 and -.866, respectively; P < .001 for both).

CONCLUSION

We observed the coexistence of increased oxidative stress and an inflammatory state among renal graft recipients.