Tatjana Cvetkovic

REVERSAL OF EXPERIMENTAL MYOGLOBINURIC ACUTE RENAL FAILURE WITH BIOFLAVONOIDS FROM SEEDS OF GRAPE

Rhabdomyolysis may account for about 10% of all cases of acute renal failure (ARF). This study was performed to explore the protective influence of proanthocyanidins from seeds of grape in an experimental model of myoglobinuric ARF. Rats were injected with 50% glycerol (8 mL/Kg, im) followed immediately and daily in the next three days by ip proanthocyanidins (20 mg/kg) or saline. After 96 h rats were sacrificed and kidney morphology, kidney cortex peptidase activities, and malondialdehyde (MDA) content were determined. A moderate renal failure was produced by glycerol injection with blood urea of 31.8 ± 11.0 vs. 7.68 ± 0.24 mmol/L, and serum creatinine of 153.6 ± 38.2 vs. 39.6 ± 9.0 μmol/L, in glycerol-induced ARF vs. control rats, respectively. Rats that received proanthocyanidins in addition to glycerol had significantly lower (p < 0.01) blood urea and serum creatinine levels compared to those receiving glycerol alone. These functional differences between the glycerol and glycerol plus proanthocianidins groups were also confirmed histologically. Kidney cortex dipeptidylpeptidase IV (DPP IV) activity was not significantly changed in glycerol-induced ARF, however, markedly increased after proanthocyanidins treatment. Kidney cortex malondialdehyde content was found significantly increased in glycerol-induced ARF over control level, and was markedly reduced by proanthocyanidin treatment. Taken together, these results provide strong evidence for the protective role of proanthocyanidins from seeds of grape in glycerol-induced ARF. The effect is probably due to the antioxidant activity of proanthocyanidins and to increased expression of kidney cortex DPP IV with effective degradation of TNF-α. This may provide therapeutic opportunities of preventing and/or treating myoglobinuric ARF in humans.

Oxidative stress parameters as possible urine markers in patients with diabetic nephropathy

OBJECTIVE Reactive oxygen species play a crucial role in the pathogenesis of diabetic nephropathy (DN). The present study was performed to assess oxidative stress parameters-thiobarbituric acid reactive substances (TBARS), reactive carbonyl derivates (RCDs), and total sulfhydryl groups (TSHGs)-in serum and urine of patients with DN. METHODS All parameters were determined in patients with type 2 and type 1 diabetes mellitus and microalbuminuria (DMT2-MIA, DMT1-MIA, respectively) and patients with type 2 diabetes mellitus and macroalbuminuria (DMT2-MAA) compared to healthy controls. RESULTS Serum and urine TBARS levels were higher in all patients with DN and microalbiminuria compared to the control group. RCD levels significantly increased in serum of patients with DMT2 relative to the controls as well as in urine of patients with DMT2-MAA and DMT1-MIA. In all groups of patients, TSHGs decreased in serum but not in urine of patients with DMT2-MAA. CONCLUSION Urine TBARS, RCDs, and TSHGs could be proposed as possible markers for oxidative damage of kidney in DN.

Circulating purine compounds, uric acid, and xanthine oxidase/dehydrogenase relationship in essential hypertension and end stage renal disease

Abstract Purine nucleotide liberation and their metabolic rate of interconversion may be important in the development of hypertension and its renal consequences. In the present study, blood triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) breakdown pathway was evaluated in relation to uric acid concentration and xanthine dehydrogenase/xanthine oxidase (XDH/XO) in patients with essential hypertension, patients with chronic renal diseases on dialysis, and control individuals. The pattern of nucleotide catabolism was significantly shifted toward catabolic compounds, including ADP, AMP, and uric acid in patients on dialysis program. A significant fall of ATP was more expressed in a group of patients on dialysis program, compared with the control value (p < 0.001), while ADP and AMP were significantly increased in both groups of patients compared with control healthy individuals (p < 0.001), together with their final degradation product, uric acid (p < 0.001). The index of ATP/ADP and ATP/uric acid showed gradual significant fall in both the groups, compared with the control value (p < 0.001), near five times in a group on dialysis. Total XOD was up-regulated significantly in a group with essential hypertension, more than in a group on dialysis. The activity of XO, which dominantly contributes reactive oxygen species (ROS) production, significantly increased in dialysis group, more than in a group with essential hypertension. In conclusion, the examination of the role of circulating purine nucleotides and uric acid in pathogenesis of hypertension and possible development of renal disease, together with XO role in ROS production, may help in modulating their liberation and ROS production in slowing progression from hypertension to renal failure.

Low Catalase Activity in Rats with Ureteral Ligation: Relation to Lipid Peroxidation

Progression of some renal diseases is characterized by generation of reactive oxygen metabolites that are also involved in the pathophysiology of obstructive nephropathy. Catalase activity and lipid peroxidation were investigated in rats with unilaterally (UUL) and bilaterally ligated ureters (BUL). Forty-eight hours after ligation, the animals were sacrificed, and enzyme activity as well as the malondialdehyde (MDA) concentration were measured in the plasma, kidneys and livers. The activity of catalase was significantly reduced in the plasma of the BUL rats and in the kidneys of both investigated groups. In the liver, catalase activity was decreased only in the BUL group. The MDA concentration in the plasma and kidneys of the BUL rats was significantly increased while in the liver it remained unchanged. These results suggest that lipid peroxidation in the induced uremic state could be responsible for catalase inactivation.

Serum neopterin, nitric oxide, inducible nitric oxide synthase and tumor necrosis factor-α levels in patients with ischemic heart disease

Abstract Background: Atherosclerosis, a chronic inflammatory disease, underlies the pathogenesis of coronary artery disease. The present study assessed the diagnostic possibilities of inflammatory biomarkers, serum neopterin, nitrite/nitrate (NO2–/NO3–), inducible nitric oxide synthase (iNOS) and tumor necrosis factor-α (TNF-α), and their correlation with risk factors in patients with acute coronary syndromes and stable angina pectoris. Methods: We studied 44 patients with chronic stable angina pectoris, 46 with unstable angina, 55 with acute ST-elevation myocardial infarction and 39 age-matched healthy volunteers (control group). Serum neopterin, iNOS and TNF-α were determined with commercially available enzyme linked immunosorbent assay methods and NO2–/NO3– by the modified cadmium-reduction method. Results: Mean serum neopterin levels were significantly higher in patients with unstable and stable angina pectoris in comparison to control subjects (p<0.01 and p<0.05, respectively). Serum NO2–/NO3– values were significantly elevated (p<0.01) only in patients with unstable angina. ST-elevation myocardial infarction patients with cardiac death during follow-up showed significantly lower baseline neopterin values (p<0.001), and higher NO2–/NO3– levels (p<0.05) in comparison to those without adverse events. Significantly higher NO2–/NO3– values (p<0.05) were also found in patients who had myocardial reinfarction. Serum iNOS and TNF-α in all patient groups were within control ranges. A strong correlation was found between neopterin and both smoking (p<0.01) and triglycerides (p<0.05) in unstable angina patients. In stable angina patients, neopterin, iNOS and TNF-α significantly correlated with hypertension (p<0.01) and triglycerides (p<0.05). A significant difference in neopterin concentration was found between smokers and non-smokers (p<0.05). Conclusions: The results of this study suggest that in stable angina patients, if studied over time, serum neopterin or NO2–/NO3– levels may indicate future plaque instability. In ST-elevation myocardial infarction patients, neopterin and/or NO2–/NO3– levels may identify patients at long-term risk of death or recurrent acute coronary events after myocardial infarction. Clin Chem Lab Med 2008;46:1149–55.

Microalbuminuria in children with vesicoureteral reflux.

Vesicoureteral reflux (VUR) is a common congenital anomaly of the urinary tract that may be inherited. Reflux of infected urine may cause scarring in susceptible kidneys with the potential to compromise renal function. The aim of the study was to evaluate the possible influence of different grades of VUR on glomerular damage using microalbuminuria as a parameter. Children with VUR detected by voiding cystourethrography (VCUG) were investigated. According to the grade of VUR, patients were separated into three groups. The first group included 12 children with VUR grade I–II. The second group consisted of 12 children with grade III of VUR. Patients with VUR grade IV–V (n = 11) were members of the third group. The control group consisted of 17 healthy children. Microalbuminuria was examined in samples of morning urine specimens using a microalbumin/creatinine reagent kit. Serum urea, creatinine levels and creatinine clearance (CCR) were measured as markers of renal function. The mean value of microalbumin excretion in the third group showed a statistically significant increase (p < 0.001) compared to all other groups. CCR in the third group was statistically significantly decreased (p < 0.05) in comparison to the group of healthy children. There were no statistically significant changes of microalbumin excretion and CCR in the first and second group compared to control values. We discussed the presence of microalbuminuria and decrease of CCR in children with high grade of VUR as a possible consequence of retrograde urine flow (intrarenal reflux), glomerulosclerosis, and consecutive hyperfiltration.

How the duration period of erythropoietin treatment influences the oxidative status of hemodialysis patients.

Background: End-stage renal disease is a state of enhanced oxidative stress (OS) and hemodialysis (HD) and renal anemia further augment this disbalance. Anemia correction with erythropoietin (EPO) may improve oxidative status. However, there is no evidence of time dependent effects of EPO therapy on redox status of HD patients. Objective: The aim of this study was to evaluate whether the duration of EPO treatment may affect OS parameters in uremic patients. Patients and methods: 104 HD patients and 29 healthy volunteers were included. Patients were divided into 3 groups according to the duration of EPO treatment. Forth group consisted of HD patients without EPO treatment. Plasma and erythrocyte malondialdehyde (MDA, MDArbc), reactive carbonyl groups (RCG), plasma sulfhydryl (-SH) groups and total antioxidative capacity (TAC) levels were evaluated. Results: HD patients both with and without EPO treatment, showed a significant increase in all oxidative parameters without significance between EPO treated and -untreated group. The decrease in MDA and MDArbc levels coincided with the duration of EPO treatment. A negative correlation was observed between the duration of EPO treatment and serum MDA (r=˗0.309, p=0.003). Increasing periods of EPO treatment were associated with decrease in RCG, without significance between EPO groups. Increase in TAC accompanied increasing durations of EPO treatment, with EPO treatment for more than 24 months causing the most striking changes (p<0.05). There were no significant differences in ˗SH levels between EPO subgroups. Conclusion: Our results suggest that long term administration of EPO attenuated the lipid peroxidation process and restored the levels of antioxidants.

Modulation of nitric oxide synthase by arginase and methylated arginines during the acute phase of experimental multiple sclerosis

We explore the nitric oxide synthase modulation by methylated arginines, asymmetric (ADMA) and symmetric (SDMA) dimethyl-l-arginine and arginase, in early phase of experimental autoimmune encephalomyelitis (EAE), the most frequently used animal model for studying the multiple sclerosis (MS), during the treatment with selective inducibile nitric oxide synthase inhibitor - aminoguanidine (AG) and oxidative scavenger N-acetyl-l-cysteine (NAC), compared to the clinical signs, continual to our previous research. The given results showed that the arginase activity was significantly increased in EAE rats compared to the healthy and AG treated EAE animals (p<0.05), and it was significantly decreased compared to the NAC treated EAE animals (p<0.05) in examined tissues. The ADMA and SDMA levels were significantly decreased in EAE untreated animals compared to the AG and NAC treated EAE animals (p<0.05). As we have reported in our previous papers, nitric oxide (NO) production, was significantly increased in examined tissues of EAE rats compared to the control group (p<0.05). In AG and NAC treated EAE group NO production was decreased in all tissues compared to untreated EAE animals (p<0.05). Also, the AG and NAC treatment of EAE rats during the development of the disease, significantly decreased the clinical score of EAE treated animals compared to EAE group. Arginase and methylated arginine derivatives, involving also NO, appear to be essential modulators of the inflammatory response in acute phase of MS. The continued research of these findings may provide a new area in the treatment of multiple sclerosis acute phase.

INF-β1b therapy modulates L-arginine and nitric oxide metabolism in patients with relapse remittent multiple sclerosis.

OBJECTIVE The scope of this study is the examination of NO(2)+NO(3), 3-nitrotyrosine (3-NT), S-nitrosothiols (RSNO), arginase activity and asymmetric (ADMA) and symmetric (SDMA) dimethyl-L-arginine concentrations in plasma of MS patients during interferon-β1b therapy. METHODS The study population included 15 (12 women, 3 men) untreated MS patients and 12 (10 women, 2 men) interferon-β1b treated MS patients with clinically definite relapsing MS (McDonalds criteria) for at least 1 year and a baseline EDSS score of 1.0 to 3.5 inclusive. Patients were treated with 250 μg IU interferon-β1b s.c. every second day during 30 months. The disease course was evaluated using correlations between baseline EDSS score and relapse rates in both groups. RESULTS During interferon-β1b treatment, EDSS scores in treated patients were decreased compared to untreated ones - after 18 and 30 months (p<0.05). In interferon-β1b treated MS patients, NO(2)+NO(3), 3-NT and RSNO plasma concentrations were significantly lower (p<0.05), while arginase activity, ADMA and SDMA levels were significantly increased (p<0.05) during the therapy, compared to the baseline levels in treated patients. CONCLUSION The investigated parameters may be the new biomarkers, providing information for the therapeutic approach and valuable in clinical monitoring.

The effects of different anesthesia techniques on free radical production after tourniquet-induced ischemia-reperfusion injury at children's age.

BACKGROUND/AIM Reperfusion of previously ischemic tissue leads to injuries mediated by reactive oxygen species. The aim of the study was to investigate the effects of different anesthesia techniques on oxidative stress caused by tourniquet-induced ischemia-reperfusion (IR) injury during extremity operations at childrens age. METHODS The study included 45 patients American Society of Anesthesiologists (ASA) classification I or II, 8 to 17 years of age, undergoing orthopedic procedures that required bloodless limb surgery. The children were randomized into three groups of 15 patients each: general inhalational anesthesia with sevoflurane (group S), total intravenous anesthesia with propofol (group T) and regional anesthesia (group R). Venous blood samples were obtained at four time points: before peripheral nerve block and induction of general anesthesia (baseline), 1 min before tourniquet release (BTR), 5 and 20 min after tourniquet release (ATR). Postischemic reperfusion injury was estimated by measurement of concentration of malondialdehyde (MDA) in plasma and erythrocytes as well as catalase (CAT) activity. RESULTS Plasma MDA concentration in the group S was significantly higher at 20 min ATR in comparison with the groups T and R (6.78 +/- 0.33 micromolL-1(-1) vs. 4.07 +/- 1.53 and 3.22 +/- 0.9. micromolL-1(-1), respectively). There was a significant difference in MDA concentration in erytrocythes between the groups S and T after 5 min of reperfusion (5.88 +/- 0.88 vs. 4.27 +/- 1.04 nmol/mlEr, p < 0.05). Although not statistically significant, CAT activity was slightly increased as compared to baseline in both groups S and R. In the group T, CAT activity decreased at all time points when compared with baseline, but the observed decrease was only statistically significant at BTR (34.70 +/- 9.27 vs. 39.69 +/- 12.91 UL-1, p < 0.05). CONCLUSION Continuous propofol infusion and regional anesthesia techniques attenuate lipid peroxidation and IR injury connected with tourniquet application in pediatric extremity surgery.