The assessment of oxidative stress on patients with chronic renal failure at different stages and on dialysis patients receiving different hypertensive treatment

Association Between Superoxide Dismutase Isoenzyme Gene Expression and Total Antioxidant Status in Patients with an End-Stage Renal Disease

Background:

Chronic renal failure, particularly end-stage renal disease, is a serious health problem associated with a high mortality rate. Uremic syndrome leads to increased oxidative stress, inflammation, and dyslipidemia.

Aims:

To examine superoxide dismutase isoenzyme gene expression in peripheral blood mononuclear cells of patients on hemodialysis and to determine the associations between superoxide dismutase isoenzyme gene expression, oxidative stress, and non-enzymatic antioxidative protection.

Study Design:

Case control study.

Methods:

This study included 33 patients on hemodialysis (age, 55.33±15.31 years old) and 33 apparently healthy controls (age, 45.37±8.92 years old). Superoxide dismutase isoenzyme messenger ribonucleic acid levels were determined by real-time polymerase chain reaction. General biochemical parameters, high sensitivity C-reactive protein, total antioxidant status, thiobarbituric acid-reactive substances, and the superoxide anion radical were also determined.

Results:

Normalized Cu/Zn superoxide dismutase and Mn superoxide dismutase messenger ribonucleic acid levels were significantly higher in patients than controls (p<0.001 and p=0.011). A significant negative correlation was detected between normalized Cu/Zn superoxide dismutase messenger ribonucleic acid levels and total protein, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total antioxidant status. Normalized Mn superoxide dismutase messenger ribonucleic acid levels were negatively correlated with total protein and total antioxidant status. A multiple regression analysis revealed independent associations between total antioxidant status and normalized Cu/Zn superoxide dismutase (p=0.038) and between total antioxidant status and normalized Mn superoxide dismutase messenger ribonucleic acid levels (p=0.038 and p=0.018, respectively).

Conclusion:

The superoxide dismutase isoenzyme gene is expressed at a higher rate in patients with end-stage renal failure, probably due to increased oxidative stress and attenuated antioxidative defense. The plasma total antioxidant status is an independent predictor of normalized superoxide dismutase isoenzyme messenger ribonucleic acid levels.

MicroRNA-155 and Anti-Müllerian Hormone: New Potential Markers of Subfertility in Men with Chronic Kidney Disease

Background/Aims

Men with terminal renal failure are often infertile. Anti-müllerian hormone (AMH), a marker of Sertoli cell function, is decreased among men with chronic kidney disease (CKD). Recently, a microRNA, miR-155, has been shown to be a potential marker for subfertility. We studied miR-155 and semen parameters in patients with CKD who were not yet on dialysis. We also aimed to study possible associations between AMH, miR-155, and semen parameters to evaluate them as markers of fertility.

Methods

Thirty male patients with CKD 1–4 as well as 18 healthy controls were enrolled.

Results

Serum levels of miR-155 were significantly higher among men with CKD stages 1–2 (4.51 ± 3.81 [p = 0.01]) and stages 3–4 (2.75 ± 1.77 [p = 0.006]) than in controls (1.09 ± 0.44). Sperm concentration was significantly lower among men with CKD 3–4 (42 ± 29) ×10⁶/mL compared to controls (88 ± 42) ×10⁶/mL (p = 0.011). High levels of miR-155 were associated with a relatively low sperm concentration (p = 0.02) and with a low total sperm number (p = 0.005). Low AMH levels were associated with a decreased percentage of motile sperm cells (p = 0.02).

Conclusions

We conclude that men with stage 3–4 CKD had lower sperm concentrations than healthy fertile men and that increased serum miR-155 in men with stage 1–4 CKD was associated with semen parameters that indicate subfertility. Low AMH levels were associated with a low percentage of the total number of motile sperm cells. miR-155 and AMH may be potential markers of subfertility in men with CKD.

Biomarkers of oxidative damage and antioxidant enzyme activities in pre-dialysis Balkan endemic nephropathy patients

AIM

To obtain more insight into molecular mechanisms underlying oxidative stress in Balkan endemic nephropathy (BEN), biomarkers of oxidative stress and antioxidant enzyme activities were studied in 38 pre-dialysis BEN patients, 21 healthy BEN family members and 36 healthy subjects from non-endemic areas.

METHODS

Protein thiol groups (P-SH), antioxidant enzyme activities [superoxide dismutase (SOD) and glutathione peroxidase (GPX)], were determined in plasma spectrophotometrically, while malondialdehyde adducts (MDA) by enzyme immunoassay.

RESULTS

BEN patients had significantly lower plasma GPX activity in comparison with values for both control groups (p = 0.016), gradually decreasing with kidney function impairment estimated by glomerular filtration rate (r = 0.53, p = 0.002). GPX activity was inversely correlated with serum urea (r = -0.627, p < 0.001), creatinine (r = -0.53, p < 0.05), urinary excretion of protein and α1-microglobulin (r = -0.44, p = 0.012; r = -0.50, p < 0.007). Significant upregulation of SOD activity was observed in healthy BEN family members (p < 0.05). While the concentration of MDA adducts was similar in all three groups, BEN patients and healthy BEN family members exhibited increased protein damage, based on fewer P-SH groups in comparison with subjects from non-BEN areas (p = 0.085; p = 0.014, respectively).

CONCLUSIONS

Based on our results on increased oxidative protein damage in both pre-dialysis BEN patients and healthy BEN family members, it can be speculated that individuals from BEN areas, in general, are chronically exposed to some prooxidant environmental compounds. Moreover, decrease in plasma GPX activity, as a consequence of impaired kidney function, could further affect oxidative status in BEN patients.

Diminished nitric oxide generation from neutrophils suppresses platelet activation in chronic renal failure

Chronic renal failure (CRF) is a complex clinical condition associated with accelerated atherosclerosis and thrombosis leading to cardiovascular events. The aim of this study was to investigate in detail the NO pathway in neutrophils obtained from hemodialysis patients and its association with platelet function and oxidative status. Fifteen CRF patients on hemodialysis and fifteen controls were included in this study. Laboratory and experimental evaluations were performed after hemodialysis in CRF patients. We evaluated L-[³H] arginine transport, NO synthase (NOS) activity, amino acid concentration in neutrophils, and expressions of NOS isoforms and p47(phox) by western blotting. Platelet aggregation was analyzed in the presence or absence of neutrophils. Oxidative status was measured through glutathione peroxidase, catalase activities, protein oxidation, lipid peroxidation, and DNA/RNA oxidation in serum. Basal NOS activity (pmol/10⁶ cells/min) was impaired in CRF patients on hemodialysis (0.33 ± 0.17) compared to controls (0.65 ± 0.12), whereas the expression of NOS isoforms remained unaltered. L-Arginine transport into neutrophils was similar in CRF patients on hemodialysis and controls. In addition, intracellular concentration of L-arginine was increased fourfold in the patient group. Systemic oxidative stress markers were not affected by CRF. On the other hand, NADPH oxidase subunit p47(phox) in neutrophils was overexpressed in CRF. In the presence of neutrophils, there was a reduction time-dependent in platelet aggregation in both groups with no difference between them. This data suggest that reduced basal generation of NO by neutrophils in CRF patients on hemodialysis occurs independently of L-arginine bioavailability and is able to suppress platelet activation.

Prevention of renal dysfunction by nutraceuticals prepared from oil rich plant foods

OBJECTIVE

To investigate the protective effect of extracts prepared from avocado, walnut, flaxseed and Eruca sativa seeds in a rat model of kidney dysfunction induced by intraperitoneal cisplatin.

METHODS

Ethanol and petroleum ether extracts mixture was prepared from each plant. Six groups of rats were conducted; control healthy, cisplatin group and four test groups where rats were given daily oral dose of each extract mixture before cisplatin injection. Different biochemical and cytogenetic parameters and kidney histopathology were determined. Acute toxicity was tested for the nutraceuticals. Total phenolic contents, fatty acids (FA) and unsaponifiable matter were assessed in the extracts.

RESULTS

Walnut ethanol extract showed the highest content of total phenolic. FA analysis revealed that all the studied plants were rich in unsaturated FA. Gas-liquid chromatographic investigation of the unsaponifiable matter showed the presence of campesterol, stigmasterol and β-sitosterol in all the studied plants. Cisplatin treatment induced significant increase in plasma urea, creatinine and malondialdehyde along with significant reduction of plasma albumin, total protein, catalase and total antioxidant as well as reduction in creatinine clearance. Histopathological examination proved the induction of kidney dysfunction. Some sorts of chromosomal aberration and sperm-shape abnormalities were noticed after cisplatin treatment. Administration of extracts mixtures produced improvements in biochemical, histopathological and cytogenetic parameters.

CONCLUSIONS

Administration of the studied nutraceuticals proved to possess protective role against cisplatin-induced nephrotoxicity, chromosomal aberration and abnormal sperms. All studied nutraceuticals showed complete safety.