Emerging role of oxidative stress in metabolic syndrome and cardiovascular diseases: important role of Rac/NADPH oxidase

Long-Term Vitamin E-Deficient Mice Exhibit Cognitive Dysfunction via Elevation of Brain Oxidation

Vitamin E inhibits oxidative processes in living tissues. We produced vitamin E-deficient mice by feeding them a vitamin E-deficient diet to verify the influence of chronic vitamin E deficiency on cognitive function. We measured cognitive function over a 5-d period using the Morris water maze task, as well as antioxidant enzyme activity and lipid peroxidation in discrete brain regions, and total serum cholesterol content. Three- and six-mo-old vitamin E-deficient and age-matched control mice were used. In addition, 24-mo-old mice were used as an aged-model. In the 3-mo-old mice, cognitive function in the vitamin E-deficient (short-term vitamin E-deficient) group was significantly impaired compared to age-matched controls. Although the lipid peroxidation products in the cerebral cortex, cerebellum and hippocampus did not significantly differ in 3-mo-old mice, the levels in the 6-mo-old vitamin E-deficient (long-term vitamin E-deficient) mice were significantly increased compared to age-matched controls. Serum cholesterol content was also significantly increased in the short- and long-term vitamin E-deficient mice compared to their respective age-matched controls. These results indicate that chronic vitamin E deficiency may slowly accelerate brain oxidation. Thus, vitamin E concentrations may need to be monitored in order to prevent the risk of cognitive dysfunction, even under normal conditions.

Nox Inhibitors & Therapies: Rational Design of Peptidic and Small Molecule Inhibitors

Oxidative stress-related diseases underlie many if not all of the major leading causes of death in United States and the Western World. Thus, enormous interest from both academia and pharmaceutical industry has been placed on the development of agents which attenuate oxidative stress. With that in mind, great efforts have been placed in the development of inhibitors of NADPH oxidase (Nox), the major enzymatic source of reactive oxygen species and oxidative stress in many cells and tissue. The regulation of a catalytically active Nox enzyme involves numerous protein-protein interactions which, in turn, afford numerous targets for inhibition of its activity. In this review, we will provide an updated overview of the available Nox inhibitors, both peptidic and small molecules, and discuss the body of data related to their possible mechanisms of action and specificity towards each of the various isoforms of Nox. Indeed, there have been some very notable successes. However, despite great commitment by many in the field, the need for efficacious and well-characterized, isoform-specific Nox inhibitors, essential for the treatment of major diseases as well as for delineating the contribution of a given Nox in physiological redox signalling, continues to grow.

Regulation of NADPH oxidases in skeletal muscle

The only known function of NAD(P)H oxidases is to produce reactive oxygen species (ROS). Skeletal muscles express three isoforms of NAD(P)H oxidases (Nox1, Nox2, and Nox4) that have been identified as critical modulators of redox homeostasis. Nox2 acts as the main source of skeletal muscle ROS during contractions, participates in insulin signaling and glucose transport, and mediates the myocyte response to osmotic stress. Nox2 and Nox4 contribute to skeletal muscle abnormalities elicited by angiotensin II, muscular dystrophy, heart failure, and high fat diet. Our review addresses the expression and regulation of NAD(P)H oxidases with emphasis on aspects that are relevant to skeletal muscle. We also summarize: i) the most widely used NAD(P)H oxidases activity assays and inhibitors, and ii) studies that have defined Nox enzymes as protagonists of skeletal muscle redox homeostasis in a variety of health and disease conditions.

Development and Validation of a Kit to Measure Drink Antioxidant Capacity Using a Novel Colorimeter

Measuring the antioxidant capacity of foods is essential, as a means of quality control to ensure that the final product reaching the consumer will be of high standards. Despite the already existing assays with which the antioxidant activity is estimated, new, faster and low cost methods are always sought. Therefore, we have developed a novel colorimeter and combined it with a slightly modified DPPH assay, thus creating a kit that can assess the antioxidant capacity of liquids (e.g., different types of coffee, beer, wine, juices) in a quite fast and low cost manner. The accuracy of the colorimeter was ensured by comparing it to a fully validated Hitachi U-1900 spectrophotometer, and a coefficient was calculated to eliminate the observed differences. In addition, a new, user friendly software was developed, in order to render the procedure as easy as possible, while allowing a central monitoring of the obtained results. Overall, a novel kit was developed, with which the antioxidant activity of liquids can be measured, firstly to ensure their quality and secondly to assess the amount of antioxidants consumed with the respective food.

Melissa officinalis L. - A review of its traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Melissa officinalis L. is a medicinal plant that has long been used in different ethno-medical systems especially in the European Traditional Medicine and the Iranian Traditional Medicine for the treatment of several diseases. It is also widely used as a vegetable and to add flavor to dishes

AIM OF THE REVIEW

This review aimed to provide a summary on the botanical characterization, traditional uses, phytochemistry, pharmacological activities, pharmacokinetics and toxicity of M. officinalis, and discusses research gaps and future opportunities for investigations on this plant.

MATERIALS AND METHODS

We extensively reviewed major unpublished old texts, and published and electronic literature on traditional medicines of different regions of the world to find traditional uses of M. officinalis. Electronic databases including Web of Science, PubMed, ScienceDirect, Google Scholar and Scopus were searched to find articles (published between 1956 and 2015) on pharmacology and phytochemistry of M. officinalis.

RESULTS

Traditional uses of M. officinalis have been recorded mostly in European countries, Mediterranean region and Middle East countries. Phytochemical investigations revealed that this plant contains volatile compounds, triterpenoids, phenolic acids and flavonoids. Crude extracts and pure compounds isolated from M. officinalis exhibited numerous pharmacological effects, from which only anxiolytic, antiviral and antispasmodic activities of this plant as well as its effects on mood, cognition and memory have been shown in clinical trials. AChE inhibitory activity, stimulation of the acetylcholine and GABAA receptors, as well as inhibition of matrix metallo proteinase-2 are the main mechanisms proposed for the widely discussed neurological effects of this plant.

CONCLUSIONS

Modern pharmacological studies have now validated many traditional uses of M. officinalis. The data reviewed here revealed that M. officinalis is a potential source for the treatment of a wide range of diseases especially anxiety and some other CNS disorders, though confirmatory trials are warranted to substantiate these effects in the clinical setting. Data regarding many aspects of this plant such as mechanisms of actions, pharmacokinetics, adverse effects of the extracts, potential interactions with standard-of-care medications and active compounds is still limited which call for additional studies particularly in humans.

Antioxidant and Antihyperlipidemic Effects of Campomanesia adamantium O. Berg Root

Campomanesia adamantium O. Berg, popularly known as guavira, has been used in Brazilian traditional medicine for reduction of serum lipid. The present study was carried out to investigate the antioxidant and antihyperlipidemic effects of Campomanesia adamantium root aqueous extract (ExCA). Phenolic compounds were quantified in the ExCA and gallic and ellagic acids were identified by HPLC. ExCA showed efficiency in 2,2-diphenyl-1-picrylhydrazyl free radical scavenging, with IC₅₀ similar to butylhydroxytoluene control, and protected the erythrocytes against lipid peroxidation induced by 2,2′-azobis(2-methylpropionamidine) dihydrochloride, reducing generated malondialdehyde. Hyperlipidemic Wistar rats treated daily by gavage during eight weeks with ExCA (200 mg/kg of body weight) showed reduced serum level of total cholesterol and triglycerides, similar to normolipidemic rats and hyperlipidemic rats treated with simvastatin (30 mg/kg of body weight) and ciprofibrate (2 mg/kg of body weight). Moreover, the treatment with ExCA also decreased malondialdehyde serum level in the hyperlipidemic rats. The body weight and organ mass were unmodified by ExCA in hyperlipidemic rats, except an increase of liver mass; however, the hepatic enzymes, alanine aminotransferase and aspartate aminotransferase, were unchanged. Together, these results confirm the potential value of Campomanesia adamantium root for lowering lipid peroxidation and lipid serum level, improving risk factors for cardiometabolic diseases development.

Asymmetric Dimethylarginine Is a Well Established Mediating Risk Factor for Cardiovascular Morbidity and Mortality-Should Patients with Elevated Levels Be Supplemented with Citrulline?

The arginine metabolite asymmetric dimethylarginine (ADMA) is a competitive inhibitor and uncoupler of endothelial nitric oxide synthase (eNOS), an enzyme that acts in multifarious ways to promote cardiovascular health. This phenomenon likely explains, at least in part, why elevated ADMA has been established as an independent risk factor for cardiovascular events, ventricular hypertrophy, and cardiovascular mortality. Fortunately, the suppressive impact of ADMA on eNOS activity can be offset by increasing intracellular arginine levels with supplemental citrulline. Although the long-term impact of supplemental citrulline on cardiovascular health in patients with elevated ADMA has not yet been studied, shorter-term clinical studies of citrulline administration demonstrate effects suggestive of increased NO synthesis, such as reductions in blood pressure and arterial stiffness, improved endothelium-dependent vasodilation, increased erection hardness, and increased ejection fractions in patients with heart failure. Supplemental citrulline could be a practical option for primary or secondary prevention of cardiovascular events and mortality, as it is inexpensive, has a mild flavor, and is well tolerated in doses (3-6 g daily) that can influence eNOS activity. Large and long-term clinical trials, targeting patients at high risk for cardiovascular events in whom ADMA is elevated, are needed to evaluate citrulline's potential for aiding cardiovascular health.

The Effect of Experimental Thyroid Dysfunction on Markers of Oxidative Stress in Rat Pancreas

Preclinical Research The aim of the present study was to evaluate the effects of thyroid dysfunction on markers of oxidative stress in rat pancreas. Hypothyroidism and hyperthyroidism were, respectively, induced in rats via administration of propylthiouracil (PTU) and L-thyroxine sodium salt in drinking water for 45 days. The activities of superoxide dismutase (SOD), catalase (CAT), glutathioen peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD), xanthine oxidase (XO), and nonenzymatic markers of oxidative stress including malondialdehyde (MDA), protein carbonyl (PC), reduced glutathione (GSH), and total thiols (T-SH) were determined in the rat pancreas. In hyperthyroid rats, pancreatic CAT, SOD, GPx, GR, XO, G6PD activities were increased compared with those in hypothyroid and control groups. There were no differences in activities of antioxidant enzymes between hypothyroid and control rats. Pancreatic MDA and PC in hyperthyroid rats increased compared with hypothyroid and the control animals. Whereas, hyperthyroid rats had decreased levels of tissue GSH and T-SH compared with hypothyroid and the control groups. The findings showed that only GSH level has decreased significantly in the hypothyroid group compared with control groups. In conclusion, our results showed that experimental hyperthyroidism induces oxidative stress in pancreas of rats, but hypothyroidism has no major impact on oxidative stress markers. Drug Dev Res 77 : 199-205, 2016.   © 2016 Wiley Periodicals, Inc.

Periostin expression induced by oxidative stress contributes to myocardial fibrosis in a rat model of high salt-induced hypertension

Periostin is an extracellular matrix protein involved in fibrosis. The present study investigated the importance of periostin in hypertension-induced myocardial fibrosis. Rats were randomly divided into either the normal group (0.4% NaCl diet; n=8) or hypertension group (8% NaCl diet; n=8). For 36 weeks, the blood pressure and heart rate of the rats were monitored. At week 36, the hearts were extracted for further analysis. Masson's staining and western blotting were performed to determine the levels of periostin protein expression, oxidative stress and fibrosis. In addition, fibroblasts were isolated from adult rats and cultured in vitro, and following treatment with angiotensin II (Ang II) and N-acetyl-L-cysteine (NAC), western blotting, immunofluorescence and 2′,7′ dichlorodihydrofluorescin staining were performed to examine reactive oxygen species production, and periostin and α-smooth muscle actin (α-SMA) expression levels. The results demonstrated that periostin expression and oxidative stress were increased in hypertensive hearts compared with normal hearts. The in vitro experiments demonstrated that Ang II upregulated the expression levels of periostin and α-SMA compared with the control, whereas, pretreatment with NAC inhibited oxidative stress, periostin and α-SMA expression in fibroblasts. In conclusion, the results of the current study suggested that oxidative stress-induced periostin is involved in myocardial fibrosis and hypertension. The present study demonstrated that periostin inhibition may be a promising approach for the inhibition of hypertension-induced cardiac remodeling.

RELATIONSHIP OF OXIDATIVE STRESS TO URINARY ANGIOTENSIN CONVERTING ENZYME 2 IN TYPE 2 DIABETES MELLITUS PATIENTS

CONTEXT

Angiotensin converting enzyme 2 (ACE2) is highly expressed in the kidney and cleaves angiotensin II to Angiotensin (1-7), annihilating the deleterious effects of angiotensin II which is known to be a strong activator of oxidative stress.

OBJECTIVE

We aimed to evaluate the relationship of oxidative stress to urinary ACE2 (uACE2) in type 2 diabetes mellitus (T2DM) patients.

DESIGN

We included consecutive normo or microalbuminuric T2DM patients in an observational transversal study. Routine laboratory investigations, plasma malondialdehyde (MDA, fluorimetric thiobarbituric method) as a marker of prooxidant capacity and superoxide dismutase (SOD, cytochrome reduction method) and catalase (CAT) activity (in erythrocyte lysate by the modification of absorbance method) as two measures of serum antioxidant capacity and uACE2 (ELISA method) were assessed.

RESULTS

MDA showed a negative correlation with SOD (r=-0.44, p=0.001), CAT (r=-0.37, p=0.006), uACE2 (r=-0.33, p=0.016) and a positive correlation with glycated haemoglobin (HbA1c) (r=0.49, p<0.001) and associated cardiovascular disease (r=0.42, p=0.001). CAT as also positively correlated to uACE2 (r=0.29, p=0.037). SOD was also negatively correlated with glycemia (r=-0.71, p<0.001) and HbA1c (r=-0.53, p<0.001). Patients with lower MDA (when divided according to median value of 3.88 nmol/mL) had higher uACE2 57.15(40.3-71.2) pg/mL compared to 38.5(31.8-45.95) pg/mL in patients with higher MDA (p<0.001). In multivariate logistic regression uACE2 was the only predictor for MDA above or below its median (OR=0.94, 95%CI[0.90-0.98], p=0.002).

CONCLUSION

Increased prooxidant serum capacity is associated with lower uACE2 levels in T2DM patients.

The association of thiol/disulphide homeostasis and lipid accumulation index with cardiovascular risk factors in overweight adolescents with polycystic ovary syndrome

OBJECTIVE

To assess thiol/disulphide homeostasis and lipid accumulation product index, and to determine whether they are associated with increased cardiovascular disease (CVD) risk or not in overweight adolescents with polycystic ovary syndrome (PCOS).

DESIGN

Case-control study.

SETTING

Education and Research Hospital.

PATIENTS

Group 1: 43 overweight+PCOS, Group 2: 45 normal weight+PCOS, Group 3: 27 overweight adolescents and Group 4: 96 age-matched, normal weight healthy controls.

INTERVENTIONS

Serum lipid profiles, hormonal parameters and thiol/disulphide homeostasis were measured. Lipid accumulation index (LAP index) and homeostasis model assessment (HOMA-IR) were calculated.

MAIN OUTCOME MEASURES

The relation between thiol/disulphide homeostasis and LAP index, and increased CVD risk were evaluated in overweight adolescents with PCOS.

RESULTS

Native and total thiol levels were significantly lower in overweight+PCOS adolescents when compared with both normal weight PCOS and control adolescents (P = 0·002). LAP index values were significantly higher in Group 1 when compared separately with the rest of the three groups (P < 0·001). Multivariable logistic regression analysis revealed serum total thiol levels of lower than 405·45 μmol/l were independently associated with increased risk of CVD in overweight PCOS adolescents (OR: 1·019, 95% CI: 1·001-1·036). In addition, a LAP index greater than 21·54 was also associated with increased CVD risk in overweight PCOS adolescents (OR: 1·270, 95% CI: 1·174-1·374).

CONCLUSION

In conclusion, we suggest that increased LAP index and decreased total thiol levels may contribute to the increased CVD risk in overweight adolescents with PCOS.

S-Adenosylmethionine suppresses the expression of Smad3/4 in activated human hepatic stellate cells via Rac1 promoter methylation

The aim of the present study was to investigate whether S-adenosylmethionine (SAM) was able to suppress activated human hepatic stellate cells (HSCs). Human LX-2 HSCs were cultured with SAM or NSC23766, and were transfected with plasmids encoding ras-related C3 botulinum toxin substrate 1 (Rac1) protein or an empty expression vector. Cell proliferation was detected by Cell Counting Kit-8. Cell migration and invasion were determined using the Transwell assay. The expression levels of Rac1 and Smad3/4 were detected by reverse transcription‑quantitative polymerase chain reaction (PCR) or western blotting. The methylation status of Rac1 promoters was measured by methylation‑specific PCR. The results demonstrated that SAM and NSC23766 suppressed the expression of Smad3/4 in LX‑2 cells. The overexpression of Rac1 enhanced the proliferation, migration and invasion of LX‑2 cells. In addition, compared with the control groups, a marked increase was observed in the protein expression levels of Smad3/4 in the LX‑2 cells transfected with Rac1 plasmids. The methylation-specific PCR findings showed that SAM increased the methylation of Rac1 promoters. The results of the present study suggested that Rac1 enhanced the expression of Smad3/4 in activated HSCs; however, this increase may be suppressed by SAM-induced methylation of Rac1 promoters.

Metabolic syndrome and selenium during gestation and lactation

PURPOSE

Selenium (Se) has a dual role in metabolic syndrome (MS) development as it has an antioxidant action against both "good" and "bad" reactive oxygen species. This study evaluates Se body profile in dams which present MS during gestation and lactation, in order to elucidate a normal dietary Se's implication in this pathology.

METHOD

Rats were randomized into control (C) and fructose (F) groups. The rich fructose diet (65 %) during gestation and lactation periods induced MS in dams. Se body distribution was determined by atomic absorption spectrophotometry, and the hepatic activity of the four antioxidant enzymes and the bimolecular oxidation were determined by spectrophotometry. The cardiac activity was monitored using the indirect tail occlusion method. Lipid and glucidic profile was also analyzed.

RESULTS

Despite the fact that the diet supplied has 0.1 ppm of Se, the minimal dietary requirement for rats, F dams ate less amount of food, and therefore, they had lower Se retention. However, they had normal levels of Se in serum and milk. Dams with MS had Se depletion in heart and muscle joint to hypertension and a lower heart rate, and Se repletion in liver and kidney. Despite the increase in hepatic glutathione peroxidase (GPx) and catalase activity found, lipid oxidation occurred-probably because superoxide dismutase activity was diminished. In heart, the activity and expression of the selenoprotein GPx1 were decreased.

CONCLUSION

With these results, it is not possible to elucidate whether a dietary Se supplementation or a Se-restricted diet are good for MS; because despite the fact that GPx activity is increased in liver, it is also found, for the first time, that heart Se deposits are significantly decreased during MS.

Serum Superoxide Dismutase Is Associated with Vascular Structure and Function in Hypertensive and Diabetic Patients

Oxidative stress is associated with cardiac and vascular defects leading to hypertension and atherosclerosis, being superoxide dismutase (SOD) one of the main intracellular antioxidant defence mechanisms. Although several parameters of vascular function and structure have a predictive value for cardiovascular morbidity-mortality in hypertensive patients, there are no studies on the involvement of SOD serum levels with these vascular parameters. Thus, we assessed if SOD serum levels are correlated with parameters of vascular function and structure and with cardiovascular risk in hypertensive and type 2 diabetic patients. We enrolled 255 consecutive hypertensive and diabetic patients and 52 nondiabetic and nonhypertensive controls. SOD levels were measured with an enzyme-linked immunosorbent assay kit. Vascular function and structure were evaluated by pulse wave velocity, augmentation index, ambulatory arterial stiffness index, and carotid intima-media thickness. We detected negative correlations between SOD and pressure wave velocity, peripheral and central augmentation index and ambulatory arterial stiffness index, pulse pressure, and plasma HDL-cholesterol, as well as positive correlations between SOD and plasma uric acid and triglycerides. Our study shows that SOD is a marker of cardiovascular alterations in hypertensive and diabetic patients, since changes in its serum levels are correlated with alterations in vascular structure and function.

Reactive oxygen species: players in the cardiovascular effects of testosterone

Androgens are essential for the development and maintenance of male reproductive tissues and sexual function and for overall health and well being. Testosterone, the predominant and most important androgen, not only affects the male reproductive system, but also influences the activity of many other organs. In the cardiovascular system, the actions of testosterone are still controversial, its effects ranging from protective to deleterious. While early studies showed that testosterone replacement therapy exerted beneficial effects on cardiovascular disease, some recent safety studies point to a positive association between endogenous and supraphysiological levels of androgens/testosterone and cardiovascular disease risk. Among the possible mechanisms involved in the actions of testosterone on the cardiovascular system, indirect actions (changes in the lipid profile, insulin sensitivity, and hemostatic mechanisms, modulation of the sympathetic nervous system and renin-angiotensin-aldosterone system), as well as direct actions (modulatory effects on proinflammatory enzymes, on the generation of reactive oxygen species, nitric oxide bioavailability, and on vasoconstrictor signaling pathways) have been reported. This mini-review focuses on evidence indicating that testosterone has prooxidative actions that may contribute to its deleterious actions in the cardiovascular system. The controversial effects of testosterone on ROS generation and oxidant status, both prooxidant and antioxidant, in the cardiovascular system and in cells and tissues of other systems are reviewed.

Comparison of antioxidant activity between green and roasted coffee beans using molecular methods

Coffee is one of the most popular and widely consumed beverages worldwide due to its pleasant taste and aroma. A number of studies have been performed to elucidate the possible beneficial effects of coffee consumption on human health and have shown that coffee exhibits potent antioxidant activity, which may be attributed mainly to its polyphenolic content. However, there is also evidence to suggest that coffee roasting (the procedure which turns green coffee beans to the dark, roasted ones from which the beverage derives) may alter the polyphenolic profile of the beans (e.g., via the Maillard reaction) and, concomitantly, their antioxidant activity. In the present study, the antioxidant activity of 13 coffee varieties was examined in both green and roasted coffee bean extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-eth-ylbenzothiazoline-6-sulfonic acid) (ABTS^•+) radical scavenging assays. In addition, 5 selected varieties were also examined for their protective effects against peroxyl and hydroxyl radical-induced DNA strand cleavage. Finally, C2C12 murine myoblasts were treated with non-cytotoxic concentrations of the most potent extract in order to examine its effects on the cellular redox status by measuring the glutathione (GSH) and reactive oxygen species (ROS) levels by flow cytometry. Our results revealed that, in 8 out of the 13 coffee varieties, roasting increased free radical scavenging activity as shown by DPPH and ABTS^•+ assays. Moreover, we found that when one coffee variety was roasted for different amounts of time, the increase in the antioxidant activity depended on the roasting time. By contrast, in 5 varieties, roasting reduced the antioxidant activity. Similar differences between the roasted and green beans were also observed in the free radical-induced DNA strand cleavage assay. The observed differences in the antioxidant activity between the different coffee varieties may be attributed to their varying polyphenolic content and composition, as well as to the different molecules produced during roasting. In addition, in the cell culture assay, the tested coffee extract led to increased GSH levels in a dose-dependent manner, indicating the enhancement of cellular antioxidant mechanisms.

Role of SIRT3 in Angiotensin II-induced human umbilical vein endothelial cells dysfunction

BACKGROUND

SIRT3, a member of the sirtuin family of NAD(+)-dependent deacetylases, resides primarily in the mitochondria and has been shown to deacetylate several metabolic and respiratory enzymes that regulate important mitochondrial functions. Previous researches show an important role of SIRT3 in regulating the production of reactive oxygen species (ROS), and highlight the ability of SIRT3 to protect cells from oxidative damage. A key substance of renin-angiotensin-aldosterone system (RAAS), Angiotensin II (AngII) can induce cells dysfunction by increasing the production of ROS. In this paper, we focus on the role of SIRT3 in AngII-induced human umbilical vein endothelial cells (HUVECs) dysfunction.

METHODS

To study the influence of AngII on SIRT3 expression, HUVECs were treated with AngII of 10(-7), 10(-6), 10(-5) mol/L for 24 h. SIRT3 expression was detected by wester-blotting analysis and RT-PCR. In addition, to research the role of SIRT3 in AngII-induced HUVECs,we used SIRT3 siRNA to knock down SIRT3 expression in HUVECs. Cells pretreated with negative control siRNA or SIRT3 siRNA were exposed to AngII for 24 h, and endothelial nitric oxide synthase (eNOS) expression, eNOS activity, total level of nitric oxide (NO) and ROS generation of each group were detected.

RESULTS

Here we show that AngII treatment could increase generation of ROS, and decrease eNOS activity and total level of NO, while upregulated eNOS expression as a compensatory mechanism. The stimulation of AngII upregulated the expression of SIRT3 in HUVECs. SIRT3 siRNA worsen the AngII-induced effects above, besides, downregulated eNOS protein expression.

CONCLUSION

These data suggest that SIRT3 plays a role of protection in AngII-induced HUVECs dysfunction via regulation of ROS generation.

Protein prenylation in islet β-cell function in health and diabetes: Putting the pieces of the puzzle together

Post-translational prenylation involves incorporation of 15-(farnesyl) or 20-(geranylgeranyl) carbon derivatives of mevalonic acid into highly conserved C-terminal cysteines of proteins. The farnesyl transferase (FTase) and the geranylgeranyl transferase (GGTase) mediate incorporation of farnesyl and geranylgeranyl groups, respectively. At least 300 proteins are prenylated in the human genome; the majority of these are implicated in cellular processes including growth, differentiation, cytoskeletal function and vesicle trafficking. From a functional standpoint, isoprenylation is requisite for targeting of modified proteins to relevant cellular compartments for regulation of effector proteins. Pharmacological and molecular biological studies have provided compelling evidence for key roles of this signaling pathway in physiological insulin secretion in normal rodent and human islets. Recent evidence indicates that inhibition of prenylation results in mislocalization of unprenylated proteins, and surprisingly, they remain in active (GTP-bound) conformation. Sustained activation of G proteins has been reported in mice lacking GGTase, suggesting alternate mechanisms for the activation of non-prenylated G proteins. These findings further raise an interesting question if mislocalized, non-prenylated and functionally active G proteins cause cellular pathology since aberrant protein prenylation has been implicated in the onset of cardiovascular disease and diabetes. Herein, we overview the existing evidence to implicate prenylation in islet function and potential defects in this signaling pathways in the diabetic β-cell. We will also identify critical knowledge gaps that need to be addressed for the development of therapeutics to halt defects in these signaling steps in β cells in models of impaired insulin secretion, metabolic stress and diabetes.

Role of Oxidative Stress in Thyroid Hormone-Induced Cardiomyocyte Hypertrophy and Associated Cardiac Dysfunction: An Undisclosed Story

Cardiac hypertrophy is the most documented cardiomyopathy following hyperthyroidism in experimental animals. Thyroid hormone-induced cardiac hypertrophy is described as a relative ventricular hypertrophy that encompasses the whole heart and is linked with contractile abnormalities in both right and left ventricles. The increase in oxidative stress that takes place in experimental hyperthyroidism proposes that reactive oxygen species are key players in the cardiomyopathy frequently reported in this endocrine disorder. The goal of this review is to shed light on the effects of thyroid hormones on the development of oxidative stress in the heart along with the subsequent cellular and molecular changes. In particular, we will review the role of thyroid hormone-induced oxidative stress in the development of cardiomyocyte hypertrophy and associated cardiac dysfunction, as well as the potential effectiveness of antioxidant treatments in attenuating these hyperthyroidism-induced abnormalities in experimental animal models.

The Ins and Outs of Small GTPase Rac1 in the Vasculature

The Rho family of small GTPases forms a 20-member family within the Ras superfamily of GTP-dependent enzymes that are activated by a variety of extracellular signals. The most well known Rho family members are RhoA (Ras homolog gene family, member A), Cdc42 (cell division control protein 42), and Rac1 (Ras-related C3 botulinum toxin substrate 1), which affect intracellular signaling pathways that regulate a plethora of critical cellular functions, such as oxidative stress, cellular contacts, migration, and proliferation. In this review, we describe the current knowledge on the role of GTPase Rac1 in the vasculature. Whereas most recent reviews focus on the role of vascular Rac1 in endothelial cells, in the present review we also highlight the functional involvement of Rac1 in other vascular cells types, namely, smooth muscle cells present in the media and fibroblasts located in the adventitia of the vessel wall. Collectively, this overview shows that Rac1 activity is involved in various functions within one cell type at distinct locations within the cell, and that there are overlapping but also cell type-specific functions in the vasculature. Chronically enhanced Rac1 activity seems to contribute to vascular pathology; however, Rac1 is essential to vascular homeostasis, which makes Rac1 inhibition as a therapeutic option a delicate balancing act.

Differential involvement of various sources of reactive oxygen species in thyroxin-induced hemodynamic changes and contractile dysfunction of the heart and diaphragm muscles

Thyroid hormones are key regulators of basal metabolic state and oxidative metabolism. Hyperthyroidism has been reported to cause significant alterations in hemodynamics, and in cardiac and diaphragm muscle functions, all of which have been linked to increased oxidative stress. However, the definite source of increased reactive oxygen species (ROS) in each of these phenotypes is still unknown. The goal of the current study was to test the hypothesis that thyroxin (T4) may produce distinct hemodynamic, cardiac, and diaphragm muscle abnormalities by differentially affecting various sources of ROS. Wild-type and T4 mice with and without 2-week treatments with allopurinol (xanthine oxidase inhibitor), apocynin (NADPH oxidase inhibitor), L-NIO (nitric oxide synthase inhibitor), or MitoTEMPO (mitochondria-targeted antioxidant) were studied. Blood pressure and echocardiography were noninvasively evaluated, followed by ex vivo assessments of isolated heart and diaphragm muscle functions. Treatment with L-NIO attenuated the T4-induced hypertension in mice. However, apocynin improved the left-ventricular (LV) dysfunction without preventing the cardiac hypertrophy in these mice. Both allopurinol and MitoTEMPO reduced the T4-induced fatigability of the diaphragm muscles. In conclusion, we show here for the first time that T4 exerts differential effects on various sources of ROS to induce distinct cardiovascular and skeletal muscle phenotypes. Additionally, we find that T4-induced LV dysfunction is independent of cardiac hypertrophy and NADPH oxidase is a key player in this process. Furthermore, we prove the significance of both xanthine oxidase and mitochondrial ROS pathways in T4-induced fatigability of diaphragm muscles. Finally, we confirm the importance of the nitric oxide pathway in T4-induced hypertension.

Simultaneous and independent tuning of RhoA and Rac1 activity with orthogonally inducible promoters

The GTPases RhoA and Rac1 are key regulators of cell spreading, adhesion, and migration, and they exert distinct effects on the actin cytoskeleton. While RhoA classically stimulates stress fiber assembly and contraction, Rac1 promotes branched actin polymerization and membrane protrusion. These competing influences are reinforced by antagonistic crosstalk between RhoA and Rac1, which has complicated efforts to identify the specific mechanisms by which each GTPase regulates cell behavior. We therefore wondered whether RhoA and Rac1 are intrinsically coupled or whether they can be manipulated independently. To address this question, we placed constitutively active (CA) RhoA under a doxycycline-inducible promoter and CA Rac1 under an orthogonal cumate-inducible promoter, and we stably introduced both constructs into glioblastoma cells. We found that doxycycline addition increased RhoA activity without altering Rac1, and similarly cumate addition increased Rac1 activity without altering RhoA. Furthermore, co-expression of both mutants enabled high activation of RhoA and Rac1 simultaneously. When cells were cultured on collagen hydrogels, RhoA activation prevented cell spreading and motility, whereas Rac1 activation stimulated migration and dynamic cell protrusions. Interestingly, high activation of both GTPases induced a third phenotype, in which cells migrated at intermediate speeds similar to control cells but also aggregated into large, contractile clusters. In addition, we demonstrate dynamic and reversible switching between high RhoA and high Rac1 phenotypes. Overall, this approach represents a unique way to access different combinations of RhoA and Rac1 activity levels in a single cell and may serve as a valuable tool for multiplexed dissection and control of mechanobiological signals.

NOX1-induced accumulation of reactive oxygen species in abdominal fat-derived mesenchymal stromal cells impinges on long-term proliferation

Mesenchymal stromal cells (MSCs) are multipotent and can be derived from different adult tissues including fat. Our repeated attempts to produce long-term proliferative cultures of rat abdominal adipose stem cells (aASCs) under normal oxygen concentration (21%) were unsuccessful. We set to examine the events controlling this cytostasis of aASCs and found that it resulted from overproduction of reactive oxygen species (ROS) that led to apoptosis. ROS overproduction in aASCs was accompanied by increased expression of NOX1 but not of NOX2 or NOX4. NOX family members are an important source of intracellular ROS pointing to NOX1 involvement in ROS accumulation. This was verified when aASCs that were grown under 3% oxygen conditions expanded long term, displaying reduced NOX1 expression and decreased ROS accumulation. NOX1 involvement in aASC cytostasis was reaffirmed when cells that were expanded under normoxic conditions in the presence of a specific NOX1 inhibitor, ML171, demonstrated reduced ROS accumulation, reduced apoptosis and long-term expansion. aASC expansion arrest was accompanied also by a weak fat differentiation and migratory potential, which was enhanced by NOX1 inhibition. This suggests an inhibitory role for NOX1-induced ROS overproduction on aASCs, their fat differentiation and migratory potential. In contrast to aASCs, similar cells produced from subcutaneous fat were easily expanded in normoxic cultures, exhibiting low ROS concentrations, a low number of apoptotic cells and improved fat differentiation and migration. Taken together, our results show, for the first time, that NOX1-induced ROS accumulation halts ASC expansion and reduces their differentiation and migratory potential under normoxic conditions. Importantly, this phenotype comprises a tissue-specific signature as it was evident in aASCs but not in subcutaneous ASCs. NOX-induced ROS accumulation and cytokine production by fat are part of the metabolic syndrome. The similarity of this phenomenon to aASC phenotype may indicate that they arise from similar molecular mechanisms.

Angelica sinensis polysaccharides inhibit endothelial progenitor cell senescence through the reduction of oxidative stress and activation of the Akt/hTERT pathway

CONTEXT

Angelica sinensis (Oliv.) Diels (Apiaceae) polysaccharides (ASP) may play a key role in anti-ischemic activity. However, the anti-atherosclerotic activity and mechanism are unknown.

OBJECTIVE

This study investigated the protective effects of ASP against ox-LDL-induced senescence of EPCs and explored its underlying molecular mechanisms.

MATERIALS AND METHODS

Mononuclear cells were isolated from bone marrow (BM) of SD rats and differentiated to EPCs. EPCs were exposed to oxidized low-density lipoprotein (ox-LDL, 10 µg/mL, 24 h) and incubated with or without high-dose (100 µg/mL, 48 h) or low-dose (20 µg/mL, 48 h) ASP. Another group of EPCs was pre-treated with Wortmannin (100 nM, 45 min), a PI3K/Akt inhibitor. EPC senescence, telomerase activity, and superoxide anion levels were assessed using SA-β-galactosidase staining, telomerase PCR-ELISA analysis, and DHE staining, respectively. The expression of related proteins, including Akt, p-Akt, hTERT, p-hTERT, and gp91phox, were detected using western blot.

RESULTS

EPCs (47.3%) were SA-β-gal positive after treatment by ox-LDL, additionally, ox-LDL significantly increased superoxide anion levels (375% versus 100%), and inhibited telomerase activity (42% versus 100%). However, the pro-senescent effect of ox-LDL was attenuated about three-fold (16.7%), superoxide anion levels were decreased more than two-fold (148%), and telomerase activity was recovered partly (88% versus 42%) in the EPCs when treated with ASP (100 µg/mL). The immunoblotting confirmed that ASP attenuated inhibition of phosphorylation of Akt and hTERT induced by ox-LDL and down-regulated increased the expression of gp91-phox. Moreover, some effects of ASP were partially abrogated in the presence of Wortmannin.

DISCUSSION

Ox-LDL induced senescence of EPCs via inhibition of telomerase activity, which was influenced by oxidative stress and the Akt/hTERT pathway. The inhibition of EPC senescence by ASP could be important for potential therapeutics.

CONCLUSION

Treatment of EPCs with ASP remarkably attenuates the harmful effects of ox-LDL via augmentation of Akt/hTERT phosphorylation and inhibition of oxidative stress.

Association of a variant in the regulatory region of NADPH oxidase 4 gene and metabolic syndrome in patients with chronic hepatitis C

Background

Given the important contribution of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system to the generation of reactive oxygen species induced by hepatitis C virus (HCV), we investigated two single nucleotide polymorphisms (SNPs) in the putative regulatory region of the genes encoding NADPH oxidase 4 catalytic subunit (NOX4) and its regulatory subunit p22phox (CYBA) and their relation with metabolic and histological variables in patients with HCV.

Methods

One hundred seventy eight naïve HCV patients (49.3% male; 65% HCV genotype 1) with positive HCV RNA were genotyped using specific primers and fluorescent-labeled probes for SNPs rs3017887 in NOX4 and −675 T → A in CYBA.

Results

No association was found between the genotype frequencies of NOX4 and CYBA SNPs and inflammation scores or fibrosis stages in the overall population. The presence of the CA + AA genotypes of the NOX4 SNP was nominally associated with a lower alanine aminotransferase (ALT) concentration in the male population (CA + AA = 72.23 ± 6.34 U/L versus CC = 100.22 ± 9.85; mean ± SEM; P = 0.05). The TT genotype of the CYBA SNP was also nominally associated with a lower ALT concentration in the male population (TT = 84.01 ± 6.77 U/L versus TA + AA = 109.67 ± 18.37 U/L; mean ± SEM; P = 0.047). The minor A-allele of the NOX4 SNP was inversely associated with the frequency of metabolic syndrome (MS) in the male population (odds ratio (OR): 0.15; 95% confidence interval (CI): 0.03 to 0.79; P = 0.025).

Conclusions

The results suggest that the evaluated NOX4 and CYBA SNPs are not direct genetic determinants of fibrosis in HCV patients, but nevertheless NOX4 rs3017887 SNP could indirectly influence fibrosis susceptibility due to its inverse association with MS in male patients.

Sevoflurane ameliorates intestinal ischemia-reperfusion-induced lung injury by inhibiting the synergistic action between mast cell activation and oxidative stress

Preconditioning with sevoflurane (SEV) can protect against ischemia-reperfusion injury in several organs, however, the benefits of SEV against acute lung injury (ALI), induced by intestinal ischemia-reperfusion (IIR), and the underlying mechanisms remain to be elucidated. The present study was designed to investigate the effects of SEV preconditioning on IIR-mediated ALI and the associated mechanisms in a rat model. Female Sprague-Dawley rats treated with 2.3% SEV or apocynin (AP), an inhibitor of NADPH oxidase, were subjected to 75 min superior mesenteric artery occlusion followed by 2 h reperfusion in the presence or absence of the mast cell degranulator compound 48/80 (CP). SEV and AP were observed to downregulate the protein expression levels of p47^phox and gp91^phox in the lungs of normal rats. IIR resulted in severe lung injury, characterized by significant increases in pathological injury scores, lung wet/dry weight ratio, protein expression levels of p47^phox, gp91^phox and ICAM-1, the presence of hydrogen peroxide, malondydehyde and interleukin-6, and the activity of myeloperoxidase. In addition, significant reductions were observed in the expression of prosurfactant protein C, accompanied by an increase in MC degranulation, demonstrated by significant elevations in the number of mast cells, expression levels of tryptase and the concentration of β-hexosaminidase. These changes were further augmented in the presence of CP. In addition, SEV and AP preconditioning significantly alleviated the above alterations induced by IIR alone or in combination with CP. These findings suggested that SEV and AP attenuated IIR-induced ALI by inhibiting NADPH oxidase and the synergistic action between oxidative stress and mast cell activation.

Glutathione prevents preterm parturition and fetal death by targeting macrophage-induced reactive oxygen species production in the myometrium

Preterm birth is an inflammatory process resulting from the massive infiltration of innate immune cells and the production of proinflammatory cytokines in the myometrium. However, proinflammatory cytokines, which induce labor in vivo, fail to induce labor-associated features in human myometrial cells (MCs). We thus aimed to investigate if reactive oxygen species (ROS) production could be the missing step between immune cell activation and MC response. Indeed, we found that ROS production is increased in the human preterm laboring myometrium (27% ROS producing cells, respectively, versus 2% in nonlaboring controls), with 90% ROS production in macrophages. Using LPS-stimulated myometrial samples and cell coculture experiments, we demonstrated that ROS production is required for labor onset. Furthermore, we showed that ROS are required first in the NADPH oxidase (NADPHox)-2/NF-κB-dependent macrophage response to inflammatory stimuli but, more importantly, to trigger macrophage-induced MCs transactivation. Remarkably, in a murine model of LPS-induced preterm labor (inducing delivery within 17 hours, with no pup survival), cotreatment with glutathione delayed labor onset up to 94 hours and prevented in utero fetal distress, allowing 46% pups to survive. These results suggest that targeting ROS production with the macrophage-permeable antioxidant glutathione could constitute a promising strategy to prevent preterm birth.

EHT 1864, a small molecule inhibitor of Ras-related C3 botulinum toxin substrate 1 (Rac1), attenuates glucose-stimulated insulin secretion in pancreatic β-cells

Glucose-stimulated insulin secretion (GSIS) in the pancreatic β-cells entails a variety of signaling mechanisms including activation of small GTP-binding proteins (G-proteins). Previous studies from our laboratory in human islets, rodent islets and clonal β-cells have demonstrated that G-proteins (e.g., Arf6, Cdc42 and Rac1) play novel roles in cytoskeletal remodeling, which is a critical step in the trafficking of insulin-laden secretory granules for fusion with plasma membrane and release of insulin. To further understand regulatory roles of Rac1 in GSIS, we utilized, herein, EHT 1864, a small molecule inhibitor, which attenuates Rac1 activation by retaining the G-protein in an inert/inactive state, thereby preventing activation of its downstream effector proteins. We demonstrate that EHT 1864 markedly attenuated GSIS in INS-1 832/13 cells. In addition, EHT 1864 significantly reduced glucose-induced activation and membrane targeting of Rac1 in INS-1 832/13 cells. This Rac1 inhibitor also suppressed glucose-induced activation of ERK1/2 and p53, but not Akt. Lastly, unlike the inhibitors of protein prenylation (simvastatin), EHT 1864 did not exert any significant effects on cell morphology (cell rounding) under the conditions it attenuated Rac1-sensitive signaling steps leading to GSIS. Based on these findings, we conclude that EHT 1864 specifically inhibits glucose-induced Rac1 activation and membrane association and associated downstream signaling events culminating in inhibition of GSIS.

Sex differences in the relationship between blood mercury concentration and metabolic syndrome risk

BACKGROUND

Mercury exposure enhances free radical production and reduces activity of anti-oxidant enzymes, resulting in detrimental health effects. Some researchers have reported an association between blood mercury and increased risk of metabolic syndrome (MetS); however, sex differences in the relationship were not fully considered.

AIM

To examine the sex differences in the relationship between blood mercury concentration and the increased risk of MetS in Korean men and women.

MATERIALS AND METHODS

A nationwide cross-sectional study was conducted to examine the relationship between blood mercury concentration and MetS in 2,976 men and 3,074 women over 19 years of age (aged 19-87 years), using data from the 2010-2012 Korean National Health and Nutrition Examination Survey (KNHANES-V). Multiple logistic regression analysis was used to assess the relationship between blood mercury concentration and the prevalence risk of MetS after adjusting for confounding variables.

RESULTS

Compared to the lowest quartile of blood mercury concentration, the OR (95 % CI) for MetS of the highest quartile in men was 1.62 (1.15-2.28) after adjusting for age, smoking status, alcohol consumption, regular exercise, and BMI. Similarly, in multiple logistic regression analysis using log2-transformed blood mercury as a continuous variable, the OR (95 % CI) for having MetS with doubling of blood mercury was 1.20 (1.05-1.36) after adjusting for the same co-variables. However, the relationship was not observed in women after adjusting for the same co-variables.

CONCLUSIONS

Blood mercury concentration was independently associated with an increased risk of MetS in men.

Asymmetric synthesis and evaluation of danshensu-cysteine conjugates as novel potential anti-apoptotic drug candidates

We have previously reported that the danshensu-cysteine conjugate N-((R)-3-benzylthio-1-methoxy-1-oxo-2-propanyl)-2-acetoxy-3-(3,4-diacetoxyphenyl) propanamide (DSC) is a potent anti-oxidative and anti-apoptotic agent. Herein, we further design and asymmetrically synthesize two diastereoisomers of DSC and explore their potential bioactivities. Our results show that DSC and its two diastereoisomers exert similar protective effects in hydrogen peroxide (H₂O₂)-induced cellular injury in SH-SY5Y cells, as evidenced by the increase of cell viability, superoxide dismutase (SOD), and reduced glutathione (GSH) activity, and glutathione peroxidase (GPx) expression, and the decrease of cellular morphological changes and nuclear condensation, lactate dehydrogenase (LDH) release, and malondialdehyde (MDA) production. In H₂O₂-stimulated human umbilical vein endothelial cells (HUVEC), DSC concentration-dependently attenuates H₂O₂-induced cell death, LDH release, mitochondrial membrane potential collapse, and modulates the expression of apoptosis-related proteins (Bcl-2, Bax, caspase-3, and caspase-9). Our results provide strong evidence that DSC and its two diastereoisomers have similar anti-oxidative activity and that DSC exerts significant vascular-protective effects, at least in part, through inhibition of apoptosis and modulation of endogenous antioxidant enzymes.

Does vitamin C deficiency promote fatty liver disease development?

Obesity and the subsequent reprogramming of the white adipose tissue are linked to human disease-complexes including metabolic syndrome and concurrent non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). The dietary imposed dyslipidemia promotes redox imbalance by the generation of excess levels of reactive oxygen species and induces adipocyte dysfunction and reprogramming, leading to a low grade systemic inflammation and ectopic lipid deposition, e.g., in the liver, hereby promoting a vicious circle in which dietary factors initiate a metabolic change that further exacerbates the negative consequences of an adverse life-style. Large epidemiological studies and findings from controlled in vivo animal studies have provided evidence supporting an association between poor vitamin C (VitC) status and propagation of life-style associated diseases. In addition, overweight per se has been shown to result in reduced plasma VitC, and the distribution of body fat in obesity has been shown to have an inverse relationship with VitC plasma levels. Recently, a number of epidemiological studies have indicated a VitC intake below the recommended daily allowance (RDA) in NAFLD-patients, suggesting an association between dietary habits, disease and VitC deficiency. In the general population, VitC deficiency (defined as a plasma concentration below 23 μM) affects around 10% of adults, however, this prevalence is increased by an adverse life-style, deficiency potentially playing a broader role in disease progression in specific subgroups. This review discusses the currently available data from human surveys and experimental models in search of a putative role of VitC deficiency in the development of NAFLD and NASH.

Seizure activity results in calcium- and mitochondria-independent ROS production via NADPH and xanthine oxidase activation

Seizure activity has been proposed to result in the generation of reactive oxygen species (ROS), which then contribute to seizure-induced neuronal damage and eventually cell death. Although the mechanisms of seizure-induced ROS generation are unclear, mitochondria and cellular calcium overload have been proposed to have a crucial role. We aim to determine the sources of seizure-induced ROS and their contribution to seizure-induced cell death. Using live cell imaging techniques in glioneuronal cultures, we show that prolonged seizure-like activity increases ROS production in an NMDA receptor-dependent manner. Unexpectedly, however, mitochondria did not contribute to ROS production during seizure-like activity. ROS were generated primarily by NADPH oxidase and later by xanthine oxidase (XO) activity in a calcium-independent manner. This calcium-independent neuronal ROS production was accompanied by an increase in intracellular [Na(+)] through NMDA receptor activation. Inhibition of NADPH or XO markedly reduced seizure-like activity-induced neuronal apoptosis. These findings demonstrate a critical role for ROS in seizure-induced neuronal cell death and identify novel therapeutic targets.

(-)-Epicatechin mitigates high-fructose-associated insulin resistance by modulating redox signaling and endoplasmic reticulum stress

We investigated the capacity of dietary (-)-epicatechin (EC) to mitigate insulin resistance through the modulation of redox-regulated mechanisms in a rat model of metabolic syndrome. Adolescent rats were fed a regular chow diet without or with high fructose (HFr; 10% w/v) in drinking water for 8 weeks, and a group of HFr-fed rats was supplemented with EC in the diet. HFr-fed rats developed insulin resistance, which was mitigated by EC supplementation. Accordingly, the activation of components of the insulin signaling cascade (insulin receptor, IRS1, Akt, and ERK1/2) was impaired, whereas negative regulators (PKC, IKK, JNK, and PTP1B) were upregulated in the liver and adipose tissue of HFr rats. These alterations were partially or totally prevented by EC supplementation. In addition, EC inhibited events that contribute to insulin resistance: HFr-associated increased expression and activity of NADPH oxidase, activation of redox-sensitive signals, expression of NF-κB-regulated proinflammatory cytokines and chemokines, and some sub-arms of endoplasmic reticulum stress signaling. Collectively, these findings indicate that EC supplementation can mitigate HFr-induced insulin resistance and are relevant for defining interventions that can prevent/mitigate MetS-associated insulin resistance.

Zinc-Excess Intake Causes the Deterioration of Renal Function Accompanied by an Elevation in Systemic Blood Pressure Primarily Through Superoxide Radical-Induced Oxidative Stress

Using rats fed 22 g/d of a control diet containing 0.005% zinc (Zn) or 2 Zn-excess diets containing 0.05% or 0.2% Zn for 4 weeks, we examined the mechanisms involved in the deterioration of renal function induced by Zn-excess intake. An increase in Zn intake elevated mean blood pressure (BP) and reduced renal blood flow (RBF) and inulin clearance in a dose-dependent manner. This decline in inulin clearance may be derived from a fall in RBF. Administration of the nitric oxide (NO) synthase inhibitor, Nω-nitro-l-arginine methyl ester, markedly increased mean BP and significantly decreased RBF in the 3 groups of rats. Administration of the exogenous superoxide radical (OO−) scavenger, tempol, significantly decreased mean BP and substantially increased RBF in all groups of rats. These observations suggest that both an elevation in systemic BP and a reduction in RBF seen in the 2 Zn-excess diet groups result from a decrease in the action of the vasodilator, NO, through the formation of peroxynitrite based on the nonenzymatic reaction of NO and increased OO−. Indeed, the activity of the endogenous OO− scavenger, copper/Zn-superoxide dismutase, was significantly reduced in the vessel wall of rats fed 2 Zn-excess diets versus a control diet. 8-Hydroxy-2′-deoxyguanosine formation caused by OO− generation was notably elevated in the kidneys of rats fed 2 Zn-excess diets relatively to rats fed a control diet. Thus, Zn-excess intake leads to the aggravation of renal function concomitantly with an increase in systemic BP predominantly through the oxidative stress caused by OO−.

Oxidative stress and schizophrenia: recent breakthroughs from an old story

PURPOSE OF REVIEW

Oxidative stress has become an exciting area of schizophrenia research, and provides ample opportunities and hope for a better understanding of its pathophysiology, which may lead to novel treatment strategies. This review describes how recent methodological advances have allowed the study of oxidative stress to tackle fundamental questions and have provided several conceptual breakthroughs to the field.

RECENT FINDINGS

Recent human studies support the notion that intrinsic susceptibility to oxidative stress may underlie the pathophysiology of schizophrenia. More than one animal model that may be relevant to study the biology of schizophrenia also shows sign of oxidative stress in the brain.

SUMMARY

These advances have made this topic of paramount importance to the understanding of schizophrenia and will play a role in advancing the treatment options. This review covers topics from the classic biochemical studies of human biospecimens to the use of magnetic resonance spectroscopy and novel mouse models, and focuses on highlighting the promising areas of research.

Mitochondrial regulation of NADPH oxidase in hindlimb unweighting rat cerebral arteries

Exposure to microgravity results in post-flight cardiovascular deconditioning and orthostatic intolerance in astronauts. Vascular oxidative stress injury and mitochondrial dysfunction have been indicated in this process. To elucidate the mechanism for this condition, we investigated whether mitochondria regulated NADPH oxidase in hindlimb unweighting (HU) rat cerebral and mesenteric arteries. Four-week HU was used to simulate microgravity in rats. Vascular superoxide generation, protein and mRNA levels of Nox2/Nox4, and the activity of NADPH oxidase were examined in the present study. Compared with control rats, the levels of superoxide increased in cerebral (P<0.001) but not in mesenteric vascular smooth muscle cells. The protein and mRNA levels of Nox2 and Nox4 were upregulated significantly (P<0.001 and P<0.001 for Nox2, respectively; P<0.001 and P<0.001 for Nox4, respectively) in HU rat cerebral arteries but not in mesenteric arteries. NADPH oxidases were activated significantly by HU (P<0.001) in cerebral arteries but not in mesenteric arteries. Chronic treatment with mitochondria-targeted antioxidant mitoTEMPO attenuated superoxide levels (P<0.001), decreased the protein and mRNA expression levels of Nox2/Nox4 (P<0.01 and P<0.05 for Nox2, respectively; P<0.001 and P<0.001 for Nox4, respectively) and the activity of NADPH oxidase (P<0.001) in HU rat cerebral arteries, but exerted no effects on HU rat mesenteric arteries. Therefore, mitochondria regulated the expression and activity of NADPH oxidases during simulated microgravity. Both mitochondria and NADPH oxidase participated in vascular redox status regulation.

Associations of retinol-binding protein 4 with oxidative stress, inflammatory markers, and metabolic syndrome in a middle-aged and elderly Chinese population

BACKGROUND

Retinol-binding protein 4 (RBP4), a novel adipokine secreted by adipocytes and the liver, has elevated levels in type 2 diabetes mellitus (T2DM). However, its association with human metabolic diseases remains controversial. The present study was designed to investigate the associations of plasma RBP4 levels with oxidative stress, inflammatory markers, and metabolic syndrome (MetS) in a Chinese population.

METHOD

We evaluated plasma RBP4 levels in a cross-sectional sample of 1748 Chinese men and women aged 50 to 70 years in Guangzhou using an in-house developed and validated sandwich ELISA. Plasma glucose, insulin, lipid profile, serum adiponectin, adipocyte fatty acid-binding protein (A-FABP), 8-iso-prostaglandin F2α (8-iso PGF2α), 13-(S)-hydroxyoctadecadienoic acid (13-HODE), high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL6), monocyte chemotactic protein 1 (MCP1) and tumor necrosis factor α (TNFα) were all measured. MetS was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian Americans.

RESULTS

Circulating RBP4 levels were positively correlated with A-FABP (r = 0.104, P < 0.001), 8-iso PGF2α (0.236, P < 0.001), and 13-HODE (0.204, P < 0.001) and were inversely correlated with HDL cholesterol (r = -0.072, P = 0.004). After multivariable adjustment, the RBP4 levels were strongly associated with MetS and its components. The ORs (95% CIs) for the comparisons of the extreme quartiles of RBP4 were 3.46 (2.87, 4.42) for MetS, 5.92 (4.47, 8.02) for hypertriglyceridemia, 1.42 (1.11, 1.68) for reduced HDL cholesterol, 1.87 (1.48, 2.36) for central obesity and 2.74 (2.15, 3.36) for hyperglycemia (all P < 0.001). When we further controlled for adipokines, markers of oxidative stress and proinflammatory response, the association of RBP4 with central obesity was abolished but not the association with other MetS components.

CONCLUSIONS

Plasma RBP4 levels are associated with an adverse profile of oxidative stress and inflammatory markers and an increased risk of MetS in this Chinese population. These associations are independent of conventional risk factors.

Relationship between blood mercury concentrations and serum γ-glutamyltranspeptidase level in Korean adults using data from the 2010 Korean National Health and Nutrition Examination Survey

BACKGROUND

Mercury and serum γ-glutamyltranspeptidase (GGT) play an important role in anti-oxidant mechanisms. This study aimed to investigate the association between blood mercury concentrations and GGT in Korean men and women.

METHODS

A nationwide cross-sectional study was conducted to examine the relationship between blood mercury concentration and serum GGT among 1959 subjects (aged 20-87 y; 965 men, 994 women), using data from the 2010 Korean National Health and Nutrition Examination Survey. The odds ratios (ORs) and 95% confidence intervals (CIs) for high GGT (≥ 75 th percentile) for both men and women were calculated across blood mercury quartiles using multiple logistic regression analyses.

RESULTS

The mean values of BMI, waist circumference, diastolic blood pressure, total cholesterol, and triglycerides were highest in the highest quartile of blood mercury concentrations in both sexes. GGT levels gradually increased in accordance with blood mercury quartiles. Compared to the lowest quartile of blood mercury concentrations, the adjusted OR (95% CI) for high GGT of the highest quartile was 2.59 (1.51-4.43) in men and 2.03 (1.13-3.67) in women.

CONCLUSION

We found a positive relationship between blood mercury concentration and serum GGT level in a representative population sample of Korean adults.

The Association between the Epicardial Adipose Tissue Thickness and Oxidative Stress Parameters in Isolated Metabolic Syndrome Patients: A Multimarker Approach

The risk for cardiovascular diseases and type 2 diabetes mellitus significantly increases in the patient population with metabolic syndrome (MeS). The present study aimed to investigate the association between the epicardial adipose tissue thickness (EATT) and the oxidative stress parameters in MeS patients. The study included 181 patients as a patient group of 92 consecutive patients with MeS and a control group of 89 consecutive patients with similar age and gender. EATT was evaluated by transthoracic echocardiography. Serum levels of total oxidant status (TOS), total antioxidative capacity (TAS), paraoxonase-1 (PON-1), and arylesterase activities were measured. EATT was higher in the MeS group compared to the control group (6.0 ± 2.0 mm and 4.0 ± 1.0 mm, resp.; P < 0.001). The level of TOS was higher in the MeS group compared to the control group (P < 0.001). Additionally, the TAS level was higher in the MeS group compared to the control group (P < 0.001). Furthermore, the serum levels of PON-1 and arylesterase were lower in the MeS group compared to the control group (P < 0.001). EAT may cause an increased risk of cardiovascular diseases by leading to increased oxidative stress in patients with MeS.

Metabolic and oxidative stress markers in Wistar rats after 2 months on a high-fat diet

BACKGROUND

Metabolic syndrome is associated with an increased risk of cardiovascular and hepatic complications. Oxidative stress in metabolic tissues has emerged as a universal feature of metabolic syndrome and its co-morbidities. We aimed to develop a rapidly and easily induced model of metabolic syndrome in rats to evaluate its impact on plasma and tissue oxidative stress.

MATERIALS AND METHODS

Metabolic syndrome was induced in rats using a high-fat diet (HFD), and these rats were compared to rats fed a normal diet (ND) for 2 months. Metabolic control was determined by measuring body weight, blood glucose, triglycerides, lipid peroxidation and protein carbonylation in plasma. Insulinemia was evaluated through the measure of C-peptide. Histological analysis was performed on the pancreas, liver and blood vessels.

RESULTS

After 2 months, the HFD induced an increase in body weight, insulin and triglycerides. Liver steatosis was also observed in the HFD group, which was associated with an increase in glycogen storage. In the pancreas, the HFD induced islet hyperplasia. Tissue oxidative stress was also increased in the liver, pancreas and blood vessels, but plasma oxidative stress remained unchanged.

CONCLUSION

This paper reports the development of a fast and easy model of rat metabolic syndrome associated with tissue oxidative stress. This model may be a good tool for the biological validation of drugs or antioxidants to limit or prevent the complications of metabolic syndrome.

Dishevelled-1 (Dvl-1) protein: a potential participant of oxidative stress induced by selenium deficiency

Oxidative stress induced by selenium deficiency has been shown to be associated with cardiovascular diseases. Nevertheless, the mechanism associated with oxidative stress induced by selenium deficiency is poorly understood. In the present study, 36 weaning C57BL/6 mice were randomly divided into 4 groups as follows: control (n =9), 4-week selenium deficiency (n =9), 8-week selenium deficiency (n = 9), and 12-week selenium deficiency (n =9). The levels of myocardial glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA) were determined by Western blotting or commercial kits. Real-time PCR was performed to detect the mRNA expression of dishevelled-1 (Dvl-1) protein. Western blotting was conducted to evaluate the protein expression levels of Dvl-1 and β-catenin. Our results demonstrated that the levels of GPx and SOD were significantly reduced, along with an increase in MDA in selenium-deficient mice. Importantly, Dvl-1 and β-catenin were clearly upregulated under oxidative stress. Collectively, our findings indicate that Dvl-1 may be an underlying participant of oxidative stress induced by selenium deficiency.