Emel Şahin

Alterations in brain antioxidant status, protein oxidation and lipid peroxidation in response to different stress models.

The aim of this study was to investigate the effects of different stress models on copper, zinc-superoxide dismutase (Cu,Zn-SOD), catalase (CAT) and selenium-dependent glutathione peroxidase (Se-GSH-Px) activities, and reduced glutathione (GSH), protein carbonyl (PC) and lipid peroxidation marker (conjugated diene (CD) and thiobarbituric acid-reactive substances (TBARS)) levels in brain of rats, and to determine the most effective stress model according to each parameter. Rats were divided into four groups as following: control group (C), immobilization stress group (IS), cold stress group (CS) and immobilization-cold stress group (ICS). All stress models increased brain Cu,Zn-SOD and CAT activities, PC, CD and TBARS levels, plasma corticosterone levels and decreased brain GSH concentrations. Se-GSH-Px activity was increased in CS and ICS groups. When all stress models were taken into consideration, the highest increases in Cu,Zn-SOD and Se-GSH-Px activities were found in CS group. The lowest GSH level was seen in IS group. The highest increases in PC and TBARS levels were found in ICS group. The highest increase of CD concentration was seen in IS and ICS groups. Our results suggest that different stress models have different degrees of influences on enzymatic and non-enzymatic antioxidant defense systems, protein oxidation and lipid peroxidation in the brain.

STRESS‐DEPENDENT INDUCTION OF PROTEIN OXIDATION, LIPID PEROXIDATION AND ANTI‐OXIDANTS IN PERIPHERAL TISSUES OF RATS: COMPARISON OF THREE STRESS MODELS (IMMOBILIZATION, COLD AND IMMOBILIZATION–COLD)

1 It is known that stress causes disruption of homeostasis and an imbalanced anti‐oxidant status in several organs. The aim of the present study was to determine the effects of three stress models on protein oxidation, lipid peroxidation and anti‐oxidant enzyme activities in the liver, kidney and heart, and to investigate the relationship between corticosterone and some oxidative stress parameters. In addition, we investigated the most effective stress model for each parameter in each tissue. 2 Thirty‐six male Wistar rats (aged 3 months old, weighing 220 ± 20 g) were divided randomly into four groups of nine rats each: control (C), immobilization stress (IS), cold stress (CS), and immobilization–cold stress (ICS). 3 Results showed that corticosterone levels were increased in all stress groups. Levels of protein carbonyl (PC), conjugated dienes (CD) and thiobarbituric acid‐reactive substances (TBARS) were increased, whereas reduced glutathione (GSH) levels were decreased in all tissues of all stress groups. Copper, zinc‐superoxide dismutase (Cu,Zn‐SOD) activities were increased in the liver and kidney of all stress groups, but were decreased in heart of the IS and CS groups. Catalase (CAT) activities were increased in liver of the CS group and in kidney and heart of all stress groups, but were decreased in liver of the IS and ICS groups. Selenium‐dependent glutathione peroxidase (Se‐GSH‐Px) activities were increased in liver of the CS and ICS groups and in heart of all stress groups, but were decreased in kidney of the IS group. Also, Se‐GSH‐Px activity levels remained unchanged in liver of the IS group and in kidney of the CS and ICS groups. The increased CAT activity and unchanged Se‐GSH‐Px activity observed in kidney suggest that H2O2 may be primarily scavenged by CAT. 4 The strong correlations between corticosterone and oxidative damage markers (e.g. protein oxidation, lipid peroxidation and GSH levels) suggest a relationship between these parameters. Liver was affected most by the CS model, whereas kidney and heart were affected most by ICS model. Stress‐induced changes in the activities of anti‐oxidant enzymes and GSH levels were found to be tissue‐ and enzyme‐specific. In conclusion, results of the present study suggest that each stress model affects the different organ tissues in different ways.

DNA methylation or histone modification status in metastasis and angiogenesis-related genes: a new hypothesis on usage of DNMT inhibitors and S-adenosylmethionine for genome stability

Metastasis is a leading cause of mortality and morbidity in cancer. This process needs angiogenesis. The biology underlying cancer, metastasis, and angiogenesis has been investigated so as to determine the therapeutic targets. Invasive and metastatic cancer cells have undergone numerous genetic and epigenetic changes, manifested by cytoskeletal changes, loss of adhesion, and expression of proteolytic enzymes that degrade the basement membrane. Additionally, in endothelial cells, some epigenetic modifications occur during the formation of angiogenesis. Researchers have used some methylation inhibitors, histone deacetylase inhibitors, or methylating agents (such as S-adenosylmethionine, SAM) against cancer and angiogenesis. Although they are effective to beat these diseases, each one results in differentiation or changes in genome structure. We review epigenetically modified genes related with angiogenesis and metastasis in cancer and endothelial cells, and suggest a new proposal. This hypothesis has discussed the importance of the usage of DNA methylation inhibitors together with SAM to prevent tumor progression and genome instability or changes resulting in additional diseases.

Is elevated serum ceruloplasmin level associated with increased risk of coronary artery disease

BACKGROUND An imbalance between the lipid peroxidation process and antioxidative protection is associated with the pathophysiology of coronary artery disease (CAD). The authors aimed to determine the relationship between the contributors of antioxidant protection, such as paraoxonase-1 (PON1) activity, albumin, vitamin C and ceruloplasmin (CP) levels, and lipid peroxidation indicators. METHODS In the present study, the activity of PON1 was measured, together with serum concentrations of a variety of lipid constituents, albumin, vitamin C and CP levels, and lipid peroxidation indicators (conjugated dienes [CDs] and thiobarbituric acid-reactive substances [TBARS]). Data were gathered from 26 nondiabetic, angiographically proven, Turkish CAD patients and 26 healthy controls living in the Antalya region (Turkey). RESULTS CAD patients had significantly lower PON1 activity, high-density lipoprotein cholesterol, vitamin C and albumin concentrations, and higher CP, CD and TBARS concentrations than the controls. In the entire study population (n=52), serum CP levels were positively correlated with TBARS and CD levels, and negatively correlated with albumin and vitamin C levels, as well as with PON1 activity. On multiple logistic regression analysis, risk factors associated with CAD included high CP and low albumin levels. CONCLUSIONS CAD patients and controls were matched for age and sex, and high CP and low albumin levels were found to be independent risk factors for CAD. The present data gathered from the study group living in the Antalya region verifies that in CAD patients, CP impairs the oxidant-antioxidant balance in favour of the oxidants.

Levels of asymmetric dimethylarginine, nitric oxide and lipid peroxidation markers in patients with end-stage renal disease having peritoneal dialysis treatment

OBJECTIVES In this study, we aimed to investigate the activities of paraoxonase-1 (PON1) and nitric oxide synthase (NOS) and the levels of asymmetric dimethylarginine (ADMA), nitric oxide (NO), oxidized low-density lipoprotein (oxLDL), ceruloplasmin (CP), thiobarbituric acid-reactive substances (TBARS), malondialdehyde (MDA), 4-hydroxynonenal (HNE) and lipids in serum of patients with end-stage renal disease (ESRD) having continuous ambulatory peritoneal dialysis (CAPD) treatment and controls living in the Antalya region, Turkey. DESIGN AND METHODS Fifty-three patients with ESRD were enrolled in this study and were treated by CAPD. As the control group (n=32), subjects with normal renal function were included. RESULTS Serum PON1 activity and high-density lipoprotein-cholesterol (HDL-C) levels were decreased in ESRD patients whereas ADMA, NO, oxLDL, CP, TBARS, MDA and HNE levels and NOS activity were increased with regard to control group. In CAPD patients, ADMA positively correlated with NO, CP, oxLDL, TBARS and MDA levels whereas negatively correlated with PON1 activity. On multiple logistic regression analysis, risk factors associated with ESRD included CP, TBARS, triglycerides (TG) and very low-density lipoprotein-cholesterol (VLDL-C) levels. CONCLUSIONS Our data have demonstrated that ESRD patients on CAPD treatment exhibit increased lipid peroxidation reactions and decreased antioxidant protection. The assay of serum HNE and MDA may be useful to evaluate the individual accumulation of these toxic aldehydes to test the efficiency of new dialysis strategies in removing them.

Effects of lycopene and apigenin on human umbilical vein endothelial cells in vitro under angiogenic stimulation.

Angiogenesis is the formation process of new blood vessels from preexisting vessels. Solid tumors need angiogenesis for growth and metastasis. The suppression of tumor growth by inhibition of neoangiogenic processes represents a potential approach to cancer treatment. Lycopene has powerful antioxidant capacities and anticarcinogenic properties. The aim of this study was to investigate the effects of lycopene on angiogenesis in vitro. For this reason, we measured in vitro angiogenesis in human umbilical vein endothelial cells including parameters of cell proliferation, tube formation, cell migration. Lycopene and apigenin were observed to block the endothelial cell proliferation in a dose-dependent manner. In addition, they significantly decreased the capillary-like tube lengths, tube formation and endothelial cell migration. This study provides indications that apigenin and lycopene, which are considered as chemopreventive agents, to be effective in vitro on endothelial cells and angiogenesis.

Inhibition of angiogenesis by S-adenosylmethionine.

Metastasis is a leading cause of mortality and morbidity in cancer. One of the steps in metastasis process is the formation of new blood vessels. Aberrant DNA methylation patterns are common in cancer cells. In recent studies, S-adenosylmethionine (SAM), which is a DNA methylating agent, has been found to have inhibitory effects on some carcinoma cells in vivo and in vitro. In the present study, we have used SAM to investigate whether it is effective against angiogenesis in vitro. Our results have shown that SAM can reduce the formation and organization of capillary-like structures of endothelial cells in tumoral environment. Besides, we have found SAM can block endothelial cell proliferation and the migration of cells towards growth factors-rich media. In conclusion, our study suggests that SAM may be used against angiogenesis as a natural bio-product.

The association of advanced glycation end-products with glutathione status

Abstract Background The aim of this study was to investigate oxidative stress with regard to the concentrations of advanced oxidation protein products (AOPP), advanced glycation end-products (AGEs), pentosidine, glycated albumin, reduced glutathione (GSH) and oxidized glutathione (GSSG), glutathione redox ratios and thiobarbituric acid-reactive substances (TBARS) in non-diabetic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Methods The study group consisted of 52 non-diabetic CAPD patients and 34 healthy controls. AOPP, AGEs, pentosidine and glycated albumin were measured in plasma, whereas GSH, GSSG and TBARS concentrations were measured in erythrocytes of both patients and controls. Results All parameters were found to be significantly increased, except the glutathione redox ratio, which was found to be decreased in patients undergoing CAPD. Multiple regression analysis showed that AGEs were the only independent predictor of glutathione redox ratio, whereas AGEs, glycated albumin and TBARS were each found to be independent predictors of albumin concentration. Conclusion Our results support the hypothesis that oxidative stress and AOPPs/AGEs constitute important risk factors in CAPD patients. The negative relationship between albumin and both AGEs and TBARS suggests that the decrease in albumin may contribute to the increased advanced glycation and lipid peroxidation. The negative relationship between glutathione redox ratio and AGEs suggests that late products of glycation play an important role in the development of oxidative stress observed in patients undergoing peritoneal dialysis treatment.

In vitro interferon γ improves the oxidative burst activity of neutrophils in patients with chronic granulomatous disease with a subtype of gp91phox deficiency.

Aim of this study Chronic granulomatous disease (CGD) is a genetically heterogeneous primary immunodeficiency caused by a defect in phagocyte production of oxygen metabolites, and resulting in infections produced by catalase-positive microorganisms and fungi. Interferon γ (IFN-γ) has a multitude of effects on the immune system. Although preliminary studies with CGD patients on treatment with IFN-γ showed that it enhanced phagocytosis and superoxide production, ongoing studies did not reveal a significant increase of this function. Here we investigated the oxidative capacity of phagocytes in different subtypes of CGD patients on treatment with IFN-γ in vitro. Material and methods Fifty-seven patients with CGD from 14 immunology centres were enrolled to our multi-centre study. Twenty-one patients were studied as controls. Oxidative burst assay with dihydrorhodamine 123 (DHR) was used and the stimulation index (SI) was calculated with respect to CGD subtypes in both neutrophils and monocytes before, and then one and 24 hours after adding IFN-γ. Results Upon comparison of the SIs of the patients’ neutrophils before in vitro IFN-γ at hour 0, and after adding IFN-γ at hour 1 and 24 were compared, and the differences were determined between hours 0-24 and hours 1-24. This difference was especially apparent between hours 1-24. In CGD subtypes, particularly in gp91phox subtype, it was seen that, following in vitro IFN-γ, SIs of neutrophils began to increase after hour 1, and that increase became more apparent at hour 24. Conclusions Our study showed that IFN-γ treatment may increase the oxidative bursting activity by increasing the superoxide production in neutrophils, particularly in gp91phox subtype.

Circulating endothelial cells in pediatric renal transplant recipients

BackgroundAn increase in the number of circulating endothelial cells (CEC) indicates endothelial damage and the risk of cardiovascular disease. The aim of our study was to investigate the association of CEC with various clinical parameters in pediatric renal transplant recipients.MethodsCEC, defined as CD45−CD146+, were enumerated by flow cytometry from the peripheral blood of 50 pediatric renal transplant recipients and 20 healthy controls. Clinical parameters, including renal function tests, fasting blood glucose, serum cholesterol and triglyceride, cyclosporine A (CsA) (trough and 2nd-hour) and tacrolimus (tac) trough blood levels and their association with CEC numbers were analyzed.ResultsCEC numbers of patients were higher than those of controls (respectively, 128 ± 89 cells/ml (42–468 cells/ml), 82 ± 33 cells/ml (32–137 cells/ml), p = 0.024). There was a statistically significant negative correlation between CEC numbers and glomerular filtration rate (GFR) (r = −0.300, p = 0.012). There was also a statistically positive association between CEC numbers and transplant duration as well as cyclosporine trough level (respectively, r = 0.397, p = 0.004, r = 0.714, p = 0.004). CEC numbers in patients on tac and CsA were similar (p = 0.716).ConclusionsOur results demonstrate that renal transplant recipients with high CsA trough blood level, longer transplant duration, and lower GFR, are at greater risk of developing endothelial damage.