Zdenka Durackova

Oxidative Stress in University Students during Examinations

Mental stress in psychiatric disease and in daily life contributes to oxidative stress in the body. In this study we investigated a connection between possible psychological stress caused by university undergraduate examinations and oxidative stress experienced by our test subjects. Some parameters of oxidative stress (single strand breaks of DNA in lymphocytes, sensitivity to lipid oxidation and antioxidant status) were studied in medical students on the day of the examination (stress condition) and compared with the same parameters obtained from the same students during the term between two examination periods (non-stress condition). The results show that in the stress condition oxidative damage to DNA and sensitivity to lipid oxidation were significantly increased (p<0.05) when compared with the same parameters in “non-stress” conditions. A significant decrease in plasma antioxidant activity (p<0.05) in students that were under stress was observed. These results suggest that during university examinations students are under increased oxidative stress.

Antioxidant systems in polymorphonuclear leucocytes of Type 2 diabetes mellitus.

Aims To examine the effect of Type 2 diabetes mellitus (DM) on enzymes of importance for oxygen‐dependent killing of microorganisms by leucocytes.

Markers of oxidative stress in children with Down syndrome.

Abstract Background: Persons with Down syndrome have increased vulnerability to oxidative stress caused by overexpression of superoxide dismutase, an antioxidant enzyme coded on chromosome 21. Increased oxidative stress may lead to oxidative damage of important macromolecules. We monitored this damage by measuring levels of different biomarkers of oxidative stress (protein carbonyls and 4-hydroxy-2-nonenal), as well as plasma antioxidant capacity, in children with Down syndrome. A total of 20 children with Down syndrome and 18 healthy individuals were recruited for this purpose. Methods: Plasma protein carbonyls were measured using an ELISA technique, 4-hydroxy-2-nonenal was monitored by HPLC and the antioxidant capacity was evaluated using a ferric reducing ability of plasma (FRAP) assay. Results: We found that children with Down syndrome had significantly elevated levels of protein carbonyls compared to healthy controls (p<0.01). Levels of 4-hydroxy-2-nonenal and antioxidant capacity were similar in both groups. Conclusion: Our results on oxidative damage to proteins confirm the assumption of increased oxidative stress in individuals with Down syndrome.

Oxidative stress in women with perimenopausal symptoms.

Objective:In this study, we examined the relationships between perimenopausal symptoms, biochemical parameters, and markers of oxidative stress in women in perimenopause and compared them with those of premenopausal women. Methods:Sixty-two women (age, 53.2 ± 5.7 y) with perimenopausal symptoms were recruited to participate in our study. The control group consisted of 18 women without perimenopausal symptoms (age, 40 ± 5 y).Clinical perimenopausal symptoms were evaluated via the questionnaire of the Menopausal Rating Scale. Our participants were checked for basic biochemical parameters. The oxidative status of our samples was determined through the examination of lipoperoxides, 8-oxoguanine (8-oxoG) levels, and the total antioxidant status (TAS). Results:Perimenopausal women had higher total cholesterol values and lower paraoxonase-1 (PON1) activity compared to reference values. Other biochemical parameters as well as 8-oxoG levels were unchanged compared with those of healthy control women. Lipoperoxide levels were significantly increased compared with those of premenopausal women. We found an indirect correlation between PON1 arylesterase (PON1 A) activity and lipoperoxide levels, between PON1 A activity and atherogenic index, between age and TAS, and between age and 8-oxoG levels. DNA repair ability and the total antioxidant status of women in perimenopause were significantly increased compared with women in premenopause. Hypercholesterolemic women had significantly increased low-density lipoprotein cholesterol levels when compared with normocholesterolemic individuals, but these values were still within the reference range. Normocholesterolemic women had significantly decreased high-density lipoprotein cholesterol levels, below the reference range. We found no correlations between perimenopausal symptoms and biochemical parameters or oxidative stress markers. Conclusions:We found that women in perimenopause are under increased oxidative stress manifested by reduced PON1 A activity and elevated lipoperoxidation, DNA repair ability, and TAS. Nutritional antioxidant supplementation may be an effective approach in improving menopausal symptoms.

Sex differences in the blood antioxidant defense system in juvenile rats with various genetic predispositions to hypertension

This study investigated the contribution of blood oxidative stress (OS) to the development of hypertension, as well as sex differences in the antioxidant defense system (ADS) in genetic models of hypertension. Nine-week-old normotensive Wistar-Kyoto (WKY) rats, borderline hypertensive rats (BHR) and spontaneously hypertensive rats (SHR) of both sexes were used. Systolic blood pressure (SBP) was determined by tail-cuff plethysmography, the trolox equivalent antioxidant capacity (TEAC) and the concentration of lipid peroxides (LP) were determined in plasma. The activity of the antioxidant enzymes Cu/Zn–superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) was determined in erythrocytes. SBP was significantly elevated in BHR and SHR in both sexes. BHR and SHR males had a higher SBP than the respective females. Sex-dependent differences in the ADS were found only in SHR, in which TEAC, SOD and CAT were significantly higher in males than in females. No differences in TEAC, SOD, CAT and GPx were observed between BHR (males and females) and WKY controls. LP levels were similar in all the groups investigated. Significant positive correlations were observed between SBP and both SOD and CAT. TEAC correlated positively with SOD and LP. As no signs of oxidative damage to lipids were found in young BHR and SHR of either sex, OS in the blood does not seem to be causatively related to the development of hypertension in these rats. However, despite activated antioxidant defenses, the positive correlation between plasma TEAC and LP suggests that oxidative damage is progressing slowly and therefore it seems to be a consequence rather than the cause of hypertension.

Targeting the urine and plasma determinants of thromboxane A2 metabolism in detection of aspirin effectiveness.

Detection of reduced aspirin effectiveness has gained significant importance since clinical consequences of aspirin resistance were reported. Nevertheless, due to differentiated molecular basis of aspirin resistance, the conflicting choice of referential method for detection of acetylsalicylic acid ineffectiveness has become troublesome. This study, using a rat model of antiplatelet therapy, examines the aptitude of selected TXB2 metabolism-based methods in the detection of acetylsalicylic acid effectiveness. We hypothesized that ex-vivo whole blood spontaneous TXB2 generation assay could be, contrary to basal TXB2 and urine 11-dTXB2, a novel surrogate measure for impaired acetylsalicylic acid-dependent inhibition of thromboxane synthesis. To address this hypothesis, we evaluated the sensitivity of TXB2 generation assay in hirudinized whole blood to detect acetylsalicylic acid-mediated inhibition of cyclooxygenase activity in healthy rats and diabetic rats treated with acetylsalicylic acid. In diabetic and control animals, both acetylsalicylic acid drenches in the dose-independent manner contributed to significant attenuation of basal plasma TXB2 and urinary 11-dTXB2 formation. Urinary concentrations of 11-dTXB2 were, contrary to basal TXB2, significantly higher, regardless of acetylsalicylic acid dose, among all diabetic groups, compared with corresponding control groups. Determination of TXB2 generation in whole blood enabled sensitive detection of dose-related acetylsalicylic acid effect in both groups, as well as increased TXB2 formation in diabetes. We showed for the first time that evaluation of spontaneous generation of TXB2 in hirudinized whole blood enables, contrary to basal plasma TXB2 and urine 11-dTXB2 concentrations, to sensitively determine the acetylsalicylic acid effect in healthy and diabetic subjects.

The effect of natural polyphenols on the oxidative stress markers in patients with diabetic nephropathy.

BACKGROUND Nephropathy remains a significant cause of morbidity and mortality in the diabetic population and is the leading cause of end-stage renal failure, hence kidney transplantations. As a result of the diabetic milieu, increased generation of reactive oxygen species is thought to play a key role in the progression of diabetic nephropathy. Aim of this study was to evaluate the effect of Pycnogenol (Pyc), the extract from Pinus pinaster, on the level of glucose, advanced glycation end products (AGE) and oxidative stress markers in patients with Diabetic nephropathy (DN). SUBJECT AND METHODS To double blind randomised placebo controlled exploratory study were enrolled 20 men with DN received daily Pyc (120mg) or a placebo. Patients were investigated before, one and three months after Pyc administration and after termination of drugs supplementation. RESULTS The level of glucose, AGEs, malondialdehyde (MDA), 8-isoprostanes (8-Iso), as well as protein carbonyls (PC) were increased in comparison to control group. We have found lower level of glucose, AGEs, MDA and 8-Iso after 3 months of Pyc administration in comparison to the beginning state and to placebo group, but these results did not reach significance. CP and TAS were not affected. CONCLUSION Our data allow us to conclude that Pycnogenoladministration reduces oxidative damage to lipids rather through the decreased glucose level than through the influence of antioxidant capacity of plasma. This study was supported by grant Ministry of Health 2012/8-ukba-8.

Effect of the French Oak Wood Extract Robuvit on Markers of Oxidative Stress and Activity of Antioxidant Enzymes in Healthy Volunteers: A Pilot Study

We examined in vitro antioxidant capacity of polyphenolic extract obtained from the wood of oak Quercus robur (QR), Robuvit, using TEAC (Trolox equivalent antioxidant capacity) method and the effect of its intake on markers of oxidative stress, activity of antioxidant enzymes, and total antioxidant capacity in plasma of 20 healthy volunteers. Markers of oxidative damage to proteins, DNA, and lipids and activities of Cu/Zn-superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were determined in the erythrocytes. We have found an in vitro antioxidant capacity of Robuvit of 6.37 micromole Trolox equivalent/mg of Robuvit. One month intake of Robuvit in daily dose of 300 mg has significantly decreased the serum level of advanced oxidation protein products (AOPP) and lipid peroxides (LP). Significantly increased activities of SOD and CAT as well as total antioxidant capacity of plasma after one month intake of Robuvit have been shown. In conclusion, we have demonstrated for the first time that the intake of Robuvit is associated with decrease of markers of oxidative stress and increase of activity of antioxidant enzymes and total antioxidant capacity of plasma in vivo.

WITHDRAWN: Natural polyphenols modify trace element status and improve clinical symptoms of attention-deficit hyperactivity disorder.

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Paraoxonase 1 and HDL subfractions in hypercholesterolemic children and adolescents

BACKGROUND Assessment of the cardiovascular disease (CVD) risk factors in children can predict clinical manifestations of atherosclerosis in adulthood. The arylesterase (PON1-A) and lactonase (PON1-L) activities of paraoxonase 1 (PON1) and lipid parameters (Total cholesterol (TCH), VLDL-cholesterol (VLDL), triacylglycerols (TAG), HDL-cholesterol (HDL), LDL-cholesterol (LDL) and LDL- and HDL-subfractions and their mutual associations in 27 hypercholesterolemic children and adolescents were investigated. METHODS Serum levels of TCH and TAG were determined using a Hitachi 911 analyser (Roche Diagnostics, Switzerland). LDL- and HDL-subfractions were determined by Lipoprint® system (Quantimetrix, Corp., USA). PON1-A and PON1-L activities were determined according to Gan et al. (1991) and Aviram and Rosenblat (2008). RESULTS PON1-A activity was higher compared to healthy children (134.1±26.2 vs. 118.16±7.05 U/ml) and PON1-L was not different from healthy controls. Increased levels of atherogenic risk factors TCH, VLDL, IDL1 subfraction and decreased levels of the antiatherogenic IDL3 and LDL1 subfractions were observed in the hypercholesterolemic children compared to reference values. Increased levels of large HDL subfractions, comparable levels of intermediate HDL and lower levels of small HDL subfractions were observed in hypercholesterolemic children compared to healthy adults (in absence of data available for healthy children). No significant correlation between PON1-A and HDL subfractions was found. PON1-L activity positively correlated with antiatherogenic large HDL1 subfraction and negatively correlated with intermediate HDL4, 5 and 6 subfractions. CONCLUSIONS The findings suggest that the PON1-L activity rather than PON1-A activity play a protective role in atherosclerosis. We confirmed atheroprotective effect of large and atherogenic properties of small HDL subfractions. The intermediate HDL subfractions probably play no atheroprotective role.