Oxidative stress and atherosclerosis

Humanin and age-related diseases: a new link?

Humanin (HN) is 24-amino acid mitochondria-associated peptide. Since its initial discovery over a decade ago, a role for HN has been reported in many biological processes such as apoptosis, cell survival, substrate metabolism, inflammatory response, and response to stressors such as oxidative stress, ischemia, and starvation. HN and its potent analogs have been shown to have beneficial effects in many age-related diseases including Alzheimer's disease, stroke, diabetes, myocardial ischemia and reperfusion, atherosclerosis, amyotrophic lateral sclerosis, and certain types of cancer both in vitro and in vivo. More recently, an association between HN levels, growth hormone/insulin-like growth factor-1 (GH/IGF axis), and life span was demonstrated using various mouse models with mutations in the GH/IGF axis. The goal of this review is to summarize the current understanding of the role of HN in aging and age-related diseases.

Use of chemical probes to detect mitochondrial ROS by flow cytometry and spectrofluorometry

Aerobic respiration is a major source of energy in eukaryotic cells. In this setting, ATP production by the mitochondrial respiratory chain relies on the availability of NADH and FADH2 to donate protons and electrons. The flux of electrons down the electron transport chain, based on a series of oxidation-reduction reactions, releases energy that allow for the transport of H(+) ions across the inner mitochondrial membrane. The resulting proton-motive force is employed to drive ATP synthesis, while the final acceptor of the electrons flowing through the respiratory chain if molecular oxygen. A side effect of this process is the generation of reactive oxygen species (ROS). While mitochondrial ROS (mtROS) production has been linked to many pathological conditions (i.e., aging and tumorigenesis), recent evidence suggests that multiple cells, including malignant cells, employ these by-products of energy production as signals to control various cellular processes. Here, we describe protocols to use chemical probes for measuring mtROS production in intact cells by flow cytometry and spectrofluorometry.

Implications of autophagy for vascular smooth muscle cell function and plasticity

Vascular smooth muscle cells (VSMCs) are fundamental in regulating blood pressure and distributing oxygen and nutrients to peripheral tissues. They also possess remarkable plasticity, with the capacity to switch to synthetic, macrophage-like, or osteochondrogenic phenotypes when cued by external stimuli. In arterial diseases such as atherosclerosis and restenosis, this plasticity seems to be critical and, depending on the disease context, can be deleterious or beneficial. Therefore, understanding the mechanisms regulating VSMC phenotype and survival is essential for developing new therapies for vascular disease as well as understanding how secondary complications due to surgical interventions develop. In this regard, the cellular process of autophagy is increasingly being recognized as a major player in vascular biology and a critical determinant of VSMC phenotype and survival. Although autophagy was identified in lesional VSMCs in the 1960s, our understanding of the implications of autophagy in arterial diseases and the stimuli promoting its activation in VSMCs is only now being elucidated. In this review, we highlight the evidence for autophagy occurring in VSMCs in vivo, elaborate on the stimuli and processes regulating autophagy, and discuss the current understanding of the role of autophagy in vascular disease.

Extracts from Leonurus sibiricus L. increase insulin secretion and proliferation of rat INS-1E insulinoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Mongolian medicine (TMM) uses preparations from herbs as one form of medication for the treatment of a diversity of diseases including diabetes mellitus (DM). We evaluated the effect of extracts from the plant Leonurus sibiricus L. (LS), used in TMM to treat typical symptoms of type 2 DM, on insulin secretion, electrophysiological properties, intracellular calcium concentration and cell proliferation of INS-1E insulinoma cells under standard cell culture conditions (SCC; 11.1mM glucose).

MATERIALS AND METHODS

Insulin secretion was measured by ELISA, electrical properties were assessed by whole cell patch clamping, intracellular calcium concentration (Cai) by Fluo-4 time lapse imaging, insulin receptor expression was verified by RT-PCR and cell proliferation assessed by CellTiter-Glo® cell viability assay.

RESULTS

Insulin released from INS-1E cells into the culture medium over 24h was significantly increased in presence of 500 mg/L aqueous LS extract (LS OWE) as well as methanolic LS extract (LS MeOH/H2O) but not in the presence of the butanol-soluble extract (LS MeOH/BuOH). Acute application of LS OWE resulted in a depolarization of the cell membrane potential paralleled by an initial increase and subsequent decline and silencing of action potential frequency, by KATP channel inhibition, persisting depolarization and an increase in Cai. The electrophysiological effects were comparable to those of 100 μM tolbutamide, which, however failed to elevate insulin secretion under SCC. Furthermore all LS extracts stimulated INS-1E cell proliferation.

CONCLUSIONS

The finding that extracts from Leonurus sibiricus L. enhance insulin secretion and/or foster cell proliferation may provide possible explanations for the underlying therapeutic principles in the empirical use of LS-containing formulations in DM and DM-related disorders as applied in TMM.

SUMO: a (oxidative) stressed protein

Redox species are produced during the physiological cellular metabolism of a normal tissue. In turn, their presence is also attributed to pathological conditions including neurodegenerative diseases. Many are the molecular changes that occur during the unbalance of the redox homeostasis. Interestingly, posttranslational protein modifications (PTMs) play a remarkable role. In fact, several target proteins are modified in their activation, localization, aggregation, and expression after the cellular stress. Among PTMs, protein SUMOylation represents a very important molecular modification pathway during "oxidative stress". It has been reported that this ubiquitin-like modification is a fine sensor for redox species. Indeed, SUMOylation pathway efficiency is affected by the exposure to oxidative species in a different manner depending on the concentration and time of application. Thus, we here report updated evidence that states the role of SUMOylation in several pathological conditions, and we also outline the key involvement of c-Jun N-terminal kinase and small ubiquitin modifier pathway cross talk.

Genome-wide association study of a heart failure related metabolomic profile among African Americans in the Atherosclerosis Risk in Communities (ARIC) study

Both the prevalence and incidence of heart failure (HF) are increasing, especially among African Americans, but no large-scale, genome-wide association study (GWAS) of HF-related metabolites has been reported. We sought to identify novel genetic variants that are associated with metabolites previously reported to relate to HF incidence. GWASs of three metabolites identified previously as risk factors for incident HF (pyroglutamine, dihydroxy docosatrienoic acid, and X-11787, being either hydroxy-leucine or hydroxy-isoleucine) were performed in 1,260 African Americans free of HF at the baseline examination of the Atherosclerosis Risk in Communities (ARIC) study. A significant association on chromosome 5q33 (rs10463316, MAF = 0.358, P-value = 1.92 × 10(-10) ) was identified for pyroglutamine. One region on chromosome 2p13 contained a nonsynonymous substitution in N-acetyltransferase 8 (NAT8) was associated with X-11787 (rs13538, MAF = 0.481, P-value = 1.71 × 10(-23) ). The smallest P-value for dihydroxy docosatrienoic acid was rs4006531 on chromosome 8q24 (MAF = 0.400, P-value = 6.98 × 10(-7) ). None of the above SNPs were individually associated with incident HF, but a genetic risk score (GRS) created by summing the most significant risk alleles from each metabolite detected 11% greater risk of HF per allele. In summary, we identified three loci associated with previously reported HF-related metabolites. Further use of metabolomics technology will facilitate replication of these findings in independent samples.

Molecular imaging reveals rapid reduction of endothelial activation in early atherosclerosis with apocynin independent of antioxidative properties

OBJECTIVE

Antioxidative drugs continue to be developed for the treatment of atherosclerosis. Apocynin is an nicotinamide adenine dinucleotide phosphate oxidase inhibitor with anti-inflammatory properties. We used contrast-enhanced ultrasound molecular imaging to assess whether short-term apocynin therapy in atherosclerosis reduces vascular oxidative stress and endothelial activation

APPROACH AND RESULTS

Genetically modified mice with early atherosclerosis were studied at baseline and after 7 days of therapy with apocynin (4 mg/kg per day IP) or saline. Contrast-enhanced ultrasound molecular imaging of the aorta was performed with microbubbles targeted to vascular cell adhesion molecule 1 (VCAM-1; MB(V)), to platelet glycoprotein Ibα (MB(Pl)), and control microbubbles (MB(Ctr)). Aortic vascular cell adhesion molecule 1 was measured using Western blot. Aortic reactive oxygen species generation was measured using a lucigenin assay. Hydroethidine oxidation was used to assess aortic superoxide generation. Baseline signal for MBV (1.3 ± 0.3 AU) and MB(Pl )(1.5 ± 0.5 AU) was higher than for MBCtr (0.5 ± 0.2 AU; P<0.01). In saline-treated animals, signal did not significantly change for any microbubble agent, whereas short-term apocynin significantly (P<0.05) reduced vascular cell adhesion molecule 1 and platelet signal (MBV: 0.3 ± 0.1; MBPl: 0.4 ± 0.1; MBCtr: 0.3 ± 0.2 AU; P=0.6 between agents). Apocynin reduced aortic vascular cell adhesion molecule 1 expression by 50% (P<0.05). However, apocynin therapy did not reduce reactive oxygen species content, superoxide generation, or macrophage content.

CONCLUSIONS

Short-term treatment with apocynin in atherosclerosis reduces endothelial cell adhesion molecule expression. This change in endothelial phenotype can be detected by molecular imaging before any measurable decrease in macrophage content and is not associated with a detectable change in oxidative burden.

Screening for subclinical atherosclerosis by noninvasive methods in asymptomatic patients with risk factors

Atherosclerosis is a leading cause of cardiovascular death due to the increasing prevalence of the disease and the impact of risk factors such as diabetes, obesity or smoking. Sudden cardiac death is the primary consequence of coronary artery disease in 50% of men and 64% of women. Currently the only available strategy to reduce mortality in the at-risk population is primary prevention; the target population must receive screening for atherosclerosis. The value of screening for subclinical atherosclerosis is still relevant, it has become standard clinical practice with the emergence of new noninvasive techniques (radio frequency [RF] measurement of intima-media thickness [RFQIMT] and arterial stiffness [RFQAS], and flow-mediated vasodilatation [FMV]), which have been used by our team since 2007 and are based on detection marker integrators which reflect the deleterious effect of risk factors on arterial remodeling before the onset of clinical events. These techniques allow the study of values according to age and diagnosis of the pathological value, the thickness of the intima media (RFQIMT), the speed of the pulse wave (RFQAS), and the degree of endothelial dysfunction (FMV). This screening is justified in asymptomatic patients with cardiovascular risk factors (hypertension, diabetes, obesity, dyslipidemia, and tobacco smoking). Studies conducted by RF coupled with two-dimensional echo since 2007 have led to a more detailed analysis of the state of the arterial wall. The various examinations allow an assessment of the degree of subclinical atherosclerosis and its impact on arterial remodeling and endothelial function. The use of noninvasive imaging in screening and early detection of subclinical atherosclerosis is reliable and reproducible and allows us to assess the susceptibility of our patients with risk factors and ensures better monitoring of atherosclerosis, thus reducing the occurrence of cardiovascular events in the long term.

Obstructive sleep apnea and coronary artery disease: from pathophysiology to clinical implications

Coronary artery disease (CAD) and obstructive sleep apnea (OSA) are both complex and significant clinical problems. The pathophysiological mechanisms that link OSA with CAD are complex and can influence the broad spectrum of conditions caused by CAD, from subclinical atherosclerosis to myocardial infarction. OSA remains a significant clinical problem among patients with CAD, and evidence suggesting its role as a risk factor for CAD is growing. Furthermore, increasing data support that CAD prognosis may be influenced by OSA and its treatment by continuous positive airway pressure (CPAP) therapy. However, stronger evidence is needed to definitely answer these questions. This paper focuses on the relationship between OSA and CAD from the pathophysiological effects of OSA in CAD, to the clinical implications of OSA and its treatment in CAD patients.

Oxidative stress in patients with cardiovascular disease and chronic renal failure

Oxidative response regulates many physiological response in human health, but if not properly regulated it could also lead to a number of deleterious effects. The importance of oxidative stress injury depends on the molecular target, the severity of the stress, and the mechanism by which the oxidative stress is imposed: it has been implicated in several diseases including cancer, neurodegenerative diseases, malaria, rheumatoid arthritis and cardiovascular and kidney disease. Most of the common diseases, such as hypertension, atherosclerosis, heart failure, and renal dysfunction, are associated with vascular functional and structural alterations including endothelial dysfunction, altered contractility, and vascular remodeling. Common to these processes is increased bioavailability of reactive oxygen species (ROS), decreased nitric oxide (NO) levels, and reduced antioxidant capacity. Oxidative processes are up-regulated also in patients with chronic renal failure (CRF) and seem to be a cause of elevated risk of morbidity and mortality in these patients. In this review, we highlight the role of oxidative stress in cardiovascular and renal disease.

VPO1 mediates ApoE oxidation and impairs the clearance of plasma lipids

OBJECTIVE

ApoE is an abundant component of chylomicron, VLDL, IDL, and HDL. It binds to multiple types of lipids and is implicated in cholesterol and triglyceride homeostasis. Oxidation of ApoE plays a crucial role in the genesis of atherosclerosis. It is proposed that heme-containing peroxidases (hPx) are major mediators of lipoprotein oxidization. Vascular peroxidase 1 (VPO1) is a recently-discovered hPx, which is expressed in cardiovascular system, lung, liver etc. and secreted into plasma. Its plasma concentration is three orders of magnitude of that of myeloperoxidase. If VPO1 mediates ApoE oxidation and affects the lipid metabolism remains to be elucidated.

METHODS

Recombinant ApoE and VPO1 were expressed and purified from stably-expressing cell lines deriving from HEK293 cells. ApoE oxidation was carried out by VPO1 in the presence of H2O2 and chloride. ApoE oxidation was verified by a variety of approaches including immunoblot and amino acid analyses. To evaluate the functional changes in VPO1-oxidized ApoE, lipid emulsion particle binding assays were employed.

RESULTS

Oxidized ApoE binds weaker to lipid emulsion particles, which mimic the large lipid complexes in vivo. In lipid efflux assay, oxidized ApoE showed reduced capability in efflux of lipids from foam cells. Mice administrated with oxidized ApoE via blood exhibited weaker clearance ability of plasma lipids.

CONCLUSIONS

Our data suggest that VPO1 is a new mediator regulating lipid homeostasis, implying a role in genesis and development of atherosclerosis.

BRCA1 is a novel target to improve endothelial dysfunction and retard atherosclerosis

OBJECTIVE

BRCA1, a tumor suppressor gene implicated in breast and ovarian cancers, exerts multiple effects on DNA repair and affords resistance against cellular stress responses. We hypothesized that BRCA1 limits endothelial cell apoptosis and dysfunction, and via this mechanism attenuates atherosclerosis.

METHODS

Loss and gain of function were achieved in cultured endothelial cells by silencing and overexpressing BRCA1, respectively. In vivo loss and gain of function were performed by generating endothelial cell-specific knockout (EC-BRCA1(-/-)) mice and administering a BRCA1 adenovirus. Well-established cell and animal models of angiogenesis and atherosclerosis were used.

RESULTS

BRCA1 is basally expressed in endothelial cells. BRCA1 overexpression protected and BRCA1 silencing exaggerated inflammation- and doxorubicin-induced endothelial cell apoptosis. Key indices of endothelial function were modulated in a manner consistent with an effect of BRCA1 to limit endothelial cell apoptosis and improve endothelial function. BRCA1 overexpression strongly attenuated the production of reactive oxygen species and upregulated endothelial nitric oxide synthase, phosphorylated endothelial nitric oxide synthase, phosphorylated Akt, and vascular endothelial growth factor-a expression. BRCA1 overexpression also improved capillary density and promoted blood flow restoration in mice subjected to hind-limb ischemia. BRCA1-overexpressing ApoE(-/-) mice fed a Western diet developed significantly less aortic plaque lesions, exhibited reduced macrophage infiltration, and generated less reactive oxygen species. Lung sections and aortic segments from EC-BRCA1(-/-) mice demonstrated greater inflammation-associated apoptosis and impaired endothelial function, respectively. BRCA1 expression was attenuated in the plaque region of human atherosclerotic carotid artery samples compared with the adjacent plaque-free area.

CONCLUSIONS

These data collectively highlight a previously unrecognized role of BRCA1 as a gatekeeper of inflammation-induced endothelial cell function and a target to limit atherosclerosis. Translational studies evaluating endothelial function and atherosclerosis in individuals with BRCA1 mutations are suggested.

Monocyte-macrophage membrane possesses free radicals scavenging activity: stimulation by polyphenols or by paraoxonase 1 (PON1)

In the current study, we analysed free radicals scavenging activity of monocytes-macrophages in the absence or presence of antioxidants such as polyphenols or paraoxonase 1 (PON1). THP-1 human monocytic cell line, murine J774A.1 macrophages, as well as human primary monocytes have the capability to scavenge free radicals, as measured by the 1-diphenyl-2-picryl-hydrazyl (DPPH) assay. This effect (which could be attributed to the cell's membrane) was cell number and incubation time dependent. Upon incubation of J774A.1 macrophages with acetylated LDL (Ac-LDL), with VLDL, or with the radical generator, AAPH, the cells' lipid peroxides content, and paraoxonase 2 (PON2) activity were significantly increased. While non-treated cells decreased DPPH absorbance by 65%, the Ac-LDL-, VLDL- or AAPH-treated cells, decreased it by only 33%, 30%, or 45%, respectively. We next analysed the effect of J774A.1 macrophage enrichment with antioxidants, such as polyphenols or PON1 on the cells' free radicals scavenging activity. Non-treated cells decreased DPPH absorbance by 50%, whereas vitamin E-, punicalagin- or PJ-treated cells significantly further decreased it, by 75%. Similarly, in PON1-treated cells DPPH absorbance was further decreased by 63%, in association with 23% increment in PON1 catalytic activity. In cells under oxidative stress [treated with AAPH-, or with oxidized LDL], PON1 activity was decreased by 31% or 40%, as compared to the activity observed in PON1 incubated with non-treated cells. We conclude that monocytes-macrophages possess free radicals scavenging activity, which is decreased under atherogenic conditions, and increased upon cell enrichment with potent antioxidants such as nutritional polyphenols, or PON1.

Antioxidant effect of apolipoprotein A-I on high-fat diet-induced non-alcoholic fatty liver disease in rabbits

Non-alcoholic fatty liver disease (NAFLD) is an increasingly recognized condition that encompasses a spectrum of liver abnormalities. It has been suggested that oxidative stress and lipid peroxidation are key pathophysiological mechanisms in NAFLD. Although an antioxidant effect of apolipoprotein A-I (apoA-I) has been reported, its influence on NAFLD has not been reported. The aim of this study was to determine whether apoA-I could improve the biochemical and histological abnormalities associated with high-fat diet-induced NAFLD through its antioxidant actions in rabbits. Liver damage was evaluated by hepatic coefficient, hepatic lipid assay, liver apparent abnormalities as well as hematoxylin-eosin staining of liver sections. Lipid peroxidation was assessed by measuring malondialdehyde (MDA) level in liver. Oxidative stress was assessed by measuring superoxide dismutase (SOD), glutathione peroxidase (GPx), and inducible nitric oxide synthase (iNOS) activities in serum and liver. Also, the mRNA expressions levels of SOD, GPx, and catalase (CAT) were determined by real-time quantitative polymerase chain reaction method. The results showed that apoA-I (20 or 40 mg/kg/w) was effective in reducing hepatic steatosis, inflammation, hepatic coefficient, and liver total cholesterol, triglyceride, low-density lipoprotein-cholesterol, and MDA levels in high-fat diet rabbits. In addition, apoA-I increased SOD and GPx activities while reducing iNOS activity in serum and liver. Moreover, apoA-I significantly increased the mRNA expression levels of SOD, GPx, and CAT in liver. This study showed that apoA-I exerted protective effects against fatty liver disease in rabbits induced by a high-fat diet, possibly through its antioxidant actions.

Urinary levels of 8-iso-prostaglandin f2α and 8-hydroxydeoxyguanine as markers of oxidative stress in patients with coronary artery disease

Background and Objectives

The objective of this study was to determine if urinary levels of 8-iso-prostaglandin F2α (8-iso-PGF2α) and 8-hydroxydeoxyguanine (8-OHdG) could be used as markers of the oxidative stress in significant coronary artery disease (CAD).

Subjects and Methods

We conducted a case-control study in 104 subjects assessed by coronary angiography with the following diagnoses: 35 consecutive cases of significant CAD and 69 cases of non-CAD with stable angina. We compared the urinary levels of 8-iso-PGF 2α and 8-OHdG, as measured by immunoassay between the 2 groups.

Results

History of hypertension was significantly higher and high density lipoprotein-cholesterol level significantly lower in the CAD group compared with those in the non-CAD group. Median levels of 8-iso-PGF2α were significantly higher in the CAD group compared with the non-CAD group (9.2 vs. 6.0 ng/mg, p=0.001). There were no significant differences in 8-OHdG values between the 2 groups. The odds ratio of 8-iso-PGF2α for CAD in the highest tertile compared with that in the lowest tertile was 7.39 (95% confidence interval; 1.71-31.91). There was no significant difference in median values of 8-iso-PGF2α between single- and multi-vessel CAD.

Conclusion

Urinary 8-iso-PGF 2α was independently associated with significant CAD in this case-control study.

Association of the C242T polymorphism in the NADPH oxidase p22 phox gene with carotid atherosclerosis in Slovenian patients with type 2 diabetes

Oxidative stress plays an important role in the pathogenesis of diabetes and its complications. Genetic variations of enzymes producing reactive oxygen species could change their activity, thus contributing to the susceptibility to oxidative stress. The aim of this study was to examine the role of the NADPH oxidase C242T polymorphism in the development of carotid atherosclerosis in patients with type 2 diabetes. 286 diabetic patients and 150 healthy controls were enrolled in the study. Carotid atherosclerosis was quantified ultrasonographically as carotid intima-media thickness, plaque score (0-6) and plaque type (1-5). Diabetic patients were divided into low and high risk groups based on ultrasound phenotypes of carotid atherosclerosis. Genotypes were determined by real-time PCR. Levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) were measured by enzyme-linked immunosorbent assay (ELISA). Diabetic patients demonstrated a statistically significant difference compared to healthy controls in the following parameters: age, BMI, waist circumference, smoking prevalence, glucose, triglyceride and 8-OHdG serum levels. Control subjects had significantly higher levels of HDL, LDL and total cholesterol than diabetics (p < 0.001). The NADPH C242T polymorphism was not related with clinical characteristics, lipid parameters and 8-OHdG serum levels. We found no significant difference in the NADPH genotype distribution between diabetics and controls (p = 0.19) nor between low and high risk subgroups of diabetics (mean CIMT: p = 0.67; plaque score: p = 0.49, plaque type: p = 0.56). In the present study the NADPH C242T polymorphism was not associated with the degree of oxidative stress and carotid atherosclerosis. Further studies will show if it can be used as a genetic marker for carotid atherosclerosis in diabetic patients.

Protective effects of Launaea procumbens on rat testis damage by CCl4

BACKGROUND

Traditionally various human diseases of kidneys, hormonal imbalance and sexual diseases are treated with Launaea procumbens (L). In the present study protective effects of methanolic extract of Launaea procumbens (LPME) was evaluated against CCl4-induced oxidative damages in rat testis.

METHODS

To examine the protective effects of Launaea procumbens on testis against oxidative stress of carbon tetrachloride in male rat, 30 male albino rats were equally divided into 5 groups (6 rats). First group was given standard diet and drinking water. Second group received CCl4 3 ml/kg intraperitoneally (30% in olive oil). Third and forth were given orally 100; 200 mg/kg b.w., in 99.8% dimethyl sulphooxide (DMSO), Launaea procumbens methanolic extracts (LPME) after 48 h of CCl4 treatment twice a week and sixth group received only LPME in DMSO at a dose of 200 mg/kg b.w., for four weeks. Protective effects of Launaea procumbens were observed on sperm concentration, motility and morphology, serum reproductive hormonal level, activity of antioxidant enzymes, lipid peroxidation (TBARS) and DNA damages.

RESULTS

Results of the present study revealed that treatment of CCl4 significantly (p < 0.01) reduced sperm concentration and motility comparatively to controls. Level of testosterone, luteinizing hormone and follicle stimulating hormone, were depleted markedly (p <0.01) with treatment of CCl4. In addition, CCl4 induction in rats reduced activities of antioxidant enzymes while increased lipid peroxidation and DNA damages. Co-administration of LPME significantly (p <0.01) improved these alterations in improving of hormonal level, activities of antioxidant enzymes and lipid peroxidation near to control rats.

CONCLUSION

From the results it is suggested that Launaea procumbens methanolic extract has the ability to protect testis against oxidative damages, possibly through antioxidant effects of its bioactive compounds.

Isoprostanes and isofurans as non-traditional risk factors for cardiovascular disease among Canadian Inuit

OBJECTIVES

The aim of the present study was to investigate the potential importance of oxidative stress, measured by isoprostanes-related compounds, as non-traditional risk factor for cardiovascular disease. We planned to examine the relationship between concentrations of plasma F₂-isoprostanes (F₂-IsoPs), isofurans (IsoFs), measures of obesity and various cardiometabolic risk factors.

MATERIALS AND METHODS

Cross-sectional study using a sub-sample from the population of a survey conducted in the summer and fall 2007 and 2008 by Canadian Coastguard Ship Amundsen in 36 Canadian Arctic Inuit communities. Subjects included a subset (n = 233) of a total study population (n = 2595) with a mean age 42.56 ± 15.39 years and body mass index 27.78 ± 5.65 kg/m². Plasma levels of F₂-IsoPs and IsoFs was determined by gas chromatography/negative ion chemical ionization/mass spectrometry (GC/NICI/MS) method; and their relationships to waist circumference (WC), blood pressure C reactive proteins (CRP), blood lipids and fasting glucose were assessed by multivariate analyses.

RESULTS

Plasma F₂-IsoPs correlated positively with CRP (r =.132, P =.048) and systolic blood pressure (SBP) (r =.157, P =.024) after adjustment for age, sex and body mass index. IsoFs correlated with WC (r =.190, P =.005) and SBP (r =.137, P =.048). F2-IsoPs were not found elevated in smokers (P =.034), whereas IsoFs were decreased in smokers (P =.001). WC, SBP and sex were found to be major correlates of oxidative stress in Canadian Inuit.

CONCLUSIONS

Plasma measures of F₂-IsoPs and IsoFs increase with increased obesity and associated cardiometabolic risk factors, including CRP and blood pressure. Simultaneous measurement of IsoFs provides an advantageous mechanistic insight into oxidative stress not captured by F₂-IsoPs alone.

Monascus-fermented dioscorea enhances oxidative stress resistance via DAF-16/FOXO in Caenorhabditis elegans

BACKGROUND

Monascus-fermented products are mentioned in an ancient Chinese pharmacopoeia of medicinal food and herbs. Monascus-fermented products offer valuable therapeutic benefits and have been extensively used in East Asia for several centuries. Several biological activities of Monascus-fermented products were recently described, and the extract of Monascus-fermented products showed strong antioxidant activity of scavenging DPPH radicals. To evaluate whether Monascus-fermented dioscorea products have potential as nutritional supplements, Monascus-fermented dioscorea's modulation of oxidative-stress resistance and associated regulatory mechanisms in Caenorhabditis elegans were investigated.

PRINCIPAL FINDINGS

We examined oxidative stress resistance of the ethanol extract of red mold dioscorea (RMDE) in C. elegans, and found that RMDE-treated wild-type C. elegans showed an increased survival during juglone-induced oxidative stress compared to untreated controls, whereas the antioxidant phenotype was absent from a daf-16 mutant. In addition, the RMDE reduced the level of intracellular reactive oxygen species in C. elegans. Finally, the RMDE affected the subcellular distribution of the FOXO transcription factor, DAF-16, in C. elegans and induced the expression of the sod-3 antioxidative gene.

CONCLUSIONS

These findings suggest that the RMDE acts as an antioxidative stress agent and thus may have potential as a nutritional supplement. Further studies in C. elegans suggest that the antioxidant effect of RMDE is mediated via regulation of the DAF-16/FOXO-dependent pathway.

Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil

Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin– angiotensin–aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.

Review on in vivo and in vitro methods evaluation of antioxidant activity

A good number of abstracts and research articles (in total 74) published, so far, for evaluating antioxidant activity of various samples of research interest were gone through where 407 methods were come across, which were repeated from 29 different methods. These were classified as in vitro and in vivo methods. And those are described and discussed below in this review article. In the later part of this review article, frequency of in vitro as well as in vivo methods is analyzed with a bar diagram. Solvents are important for extracting antioxidants from natural sources. Frequency of solvents used for extraction is also portrayed and the results are discussed in this article. As per this review there are 19 in vitro methods and 10 in vivo methods that are being used for the evaluation of antioxidant activity of the sample of interest. DPPH method was found to be used mostly for the in vitro antioxidant activity evaluation purpose while LPO was found as mostly used in vivo antioxidant assay. Ethanol was with the highest frequency as solvent for extraction purpose.

Weight loss is associated with improved endothelial dysfunction via NOX2-generated oxidative stress down-regulation in patients with the metabolic syndrome

The aim of this study was to assess whether adherence to a restricted-calorie, Mediterranean-type diet improves endothelial dysfunction and markers of oxidative stress in patients with metabolic syndrome. A moderately low-calorie (600 calories/day negative energy balance), low-fat, high-carbohydrate diet (<30% energy from fat, <10% from saturated fat and 55% from carbohydrate) was prescribed to 53 outpatients with the metabolic syndrome. Participants were divided into two groups according to body weight loss > or < 5% after 6 months. Group A (n = 23) showed a remarkable decrease in body weight (-6.8%), body-mass-index (-4.6%), waist circumference (-4.8%), HOMA-IR (-27.2%), plasma glucose, glycosylated haemoglobin, total and LDL-cholesterol, blood pressure, serum NOX2 (the catalytic core of NADPH oxidase) (-22.2%) and urinary8-isoprostanes (-39.0%) and an increase of serum NOx (Nitrite/Nitrate) (+116.8%) and adiponectine (+125.5%) as compared with those in group B (n = 30). A statistically significant increase in brachial artery flow-mediated dilatation was observed in group A (+24.7%; p < 0.001), while no changes were present in group B. Variations of flow-mediated dilatation were statistically and negatively correlated with changes of serum NOX2 levels (p = 0.04), body-mass-index (p < 0.01), waist circumference (0.01), glycosylated haemoglobin (p < 0.01), LDL-cholesterol (p < 0.01) and triglycerides (p < 0.05) and positively correlated with changes of serum NOx (p < 0.001) and adiponectin (p = 0.01). The results show that moderate weight loss is able to improve endothelial dysfunction in patients with the metabolic syndrome. The coexistent decrease of NOX2 activation suggests a role for oxidative stress in eliciting artery dysfunction.

Angiotensin II enhances AT1-Nox1 binding and stimulates arterial smooth muscle cell migration and proliferation through AT1, Nox1, and interleukin-18

The redox-sensitive transcription factors NF-κB and activator protein-1 (AP-1) are critical mediators of ANG II signaling. The promitogenic and promigratory factor interleukin (IL)-18 is an NF-κB- and AP-1-responsive gene. Therefore, we investigated whether ANG II-mediated smooth muscle cell (SMC) migration and proliferation involve IL-18. ANG II induced rat carotid artery SMC migration and proliferation and IL-18 and metalloproteinase (MMP)-9 expression via ANG II type 1 (AT(1)) receptor. ANG II-induced superoxide generation, NF-κB and AP-1 activation, and IL-18 and MMP-9 induction were all markedly attenuated by losartan, diphenyleneiodonium chloride (DPI), and Nox1 knockdown. Similar to ANG II, addition of IL-18 also induced superoxide generation, activated NF-κB and AP-1, and stimulated SMC migration and proliferation, in part via Nox1, and both ANG II and IL-18 induced NOX1 transcription in an AP-1-dependent manner. AT(1) physically associates with Nox1 in SMC, and ANG II enhanced this binding. Interestingly, exogenous IL-18 neither induced AT(1) binding to Nox1 nor enhanced the ANG II-induced increase in AT(1)/Nox1 binding. Importantly, IL-18 knockdown, or pretreatment with IL-18 neutralizing antibodies, or IL-18 binding protein, all attenuated the migratory and mitogenic effects of ANG II. Continuous infusion of ANG II for 7 days induced carotid artery hyperplasia in rats via AT(1) and was associated with increased AT(1)/Nox1 binding (despite lower AT(1) levels); increased DPI-inhibitable superoxide production; increased phospho-IKKβ, JNK, p65, and c-Jun; and induction of IL-18 and MMP-9 in endothelium-denuded carotid arteries. These results indicate that IL-18 amplifies the ANG II-induced, redox-dependent inflammatory cascades by activating similar promitogenic and promigratory signal transduction pathways. The ANG II/Nox1/IL-18 pathway may be critical in hyperplastic vascular diseases, including atherosclerosis and restenosis.

Heterogeneity in apoptotic responses of microvascular endothelial cells to oxidative stress

Oxidative stress contributes to disease and can alter endothelial cell (EC) function. EC from different vascular beds are heterogeneous in structure and function, thus we assessed the apoptotic responses of EC from lung and heart to oxidative stress. Since protein kinase Cδ (PKCδ) is activated by oxidative stress and is an important modulator of apoptosis, experiments assessed the level of apoptosis in fixed lung and heart sections of PKCδ wild-type (PKCδ(+/+)) and null (PKCδ(-/-)) mice housed under normoxia (21% O(2)) or hyperoxia (~95% O(2)). We noted a significantly greater number of TUNEL-positive cells in lungs of hyperoxic PKCδ(+/+) mice, compared to matched hearts or normoxic organs. We found that 33% of apoptotic cells identified in hyperoxic lungs of PKCδ(+/+) mice were EC, compared to 7% EC in hyperoxic hearts. We further noted that EC apoptosis was significantly reduced in lungs of PKCδ(-/-) hyperoxic mice, compared to lungs of PKCδ(+/+) hyperoxic mice. In vitro, both hyperoxia and H(2)O(2) promoted apoptosis in EC isolated from microvasculature of lung (LMVEC), but not from the heart (HMVEC). H(2)O(2) treatment significantly increased p38 activity in LMVEC, but not in HMVEC. Inhibition of p38 attenuated H(2)O(2)-induced LMVEC apoptosis. Baseline expression of total PKCδ protein, as well as the caspase-mediated, catalytically active PKCδ cleavage fragment, was higher in LMVEC, compared to HMVEC. PKCδ inhibition significantly attenuated H(2)O(2)-induced LMVEC p38 activation. Conversely, overexpression of wild-type PKCδ or the catalytically active PKCδ cleavage product greatly increased H(2)O(2)-induced HMVEC caspase and p38 activation. We propose that enhanced susceptibility of lung EC to oxidant-induced apoptosis is due to increased PKCδ→p38 signaling, and we describe a PKCδ-centric pathway which dictates the differential response of EC from distinct vascular beds to oxidative stress.

Characterization of oxidation products from 1-palmitoyl-2-linoleoyl-sn-glycerophosphatidylcholine in aqueous solutions and their reactions with cysteine, histidine and lysine residues

This report focuses on studies of lipid peroxidation products reactivity towards the side chains of cysteine, histidine, and lysine residues in structurally unordered peptides. Thus we have analyzed linoleic acid peroxidation products (LaPP) obtained by incubating 1-palmitoyl-2-linoleoyl-sn-glycerophosphatidylcholine (PLPC) overnight with or without H(2)O(2) in the presence or absence of CuCl. In total, 55 different LaPP were identified with 26 containing reactive carbonyl groups. The strongest oxidation conditions (H(2)O(2) and Cu(I), i.e. a Fenton-like reagent) yielded 51 LaPP, whereas air oxidation produced only 12 LaPP. Independent of the oxidation conditions, around half of all LaPP were short-chain (oxidative cleavage) and the others long-chain (oxygen addition) PLPC oxidation products. The stronger oxidation conditions increased the number of LaPP, but also oxidized the added peptide Ac-PAAPAAPAPAEXTPV-OH (X=Cys, His or Lys) very quickly, especially under Fenton conditions. Thus, PLPC was oxidized by milder conditions (air or Cu(I)), incubated with the peptide and the peptide modifications were then analyzed by nano-RPC-ESI-Orbitrap-MS. Ten LaPP-derived peptide modifications were identified at lysine, whereas nine products were identified for cysteine and only three for histidine. Three high molecular weight LaPP still esterified to the GPC backbone were detected on Lys-containing peptide. Furthermore, three LaPP-derived mass shifts were obtained at cysteine, which have not previously been reported.

Association of C47T polymorphism in SOD2 gene with coronary artery disease: a case-control study and a meta-analysis

Oxidative damage promotes atherosclerosis. SOD2 is an important antioxidant enzyme. A case-control study and a meta-analysis were performed to assess the association of C47T polymorphism in SOD2 gene with premature, late-onset and overall coronary artery disease (CAD) risk. A hospital-based case-control study was conducted with 269 premature CAD cases, 278 late-onset CAD cases and 299 healthy controls. Polymerase chain reaction (PCR) and Pyrosequencing were used to detect the polymorphism. Multinomial logistic regression model was performed to estimate odds ratio (OR) with 95% confidence intervals (CIs) and adjust potential confounders. A meta-analysis was performed using eight outcomes including our result. Fixed or random effect pooled measure was selected on the basis of homogeneity test among studies. Heterogeneity among studies was evaluated using I (2). Meta-regression was used to explore potential sources of between-study heterogeneity. Publication bias was estimated using Peters's linear regression test. In our case-control study, compared with the TT as the reference, the mutant genotype of CC + TC was significantly associated with a reduced premature CAD risk both in univariate (OR = 0.60, 95% CI = 0.41-0.87) and multivariate (OR = 0.59, 95% CI = 0.40-0.87) logistic regressions, but not with late-onset CAD risk. After excluding one article that deviated from Hardy-Weinberg equilibrium in controls, this meta-analysis showed a significant association of the C allele with reduced risk of CAD in dominant (FEM: OR = 0.69, 95% CI = 0.61-0.78), recessive (OR = 0.64, 95% CI = 0.50-0.82), and codominant (FEM: OR = 0.73, 95% CI = 0.65-0.80) models. Our study suggested that the mutant genotype of CC + TC was significantly associated with a reduced CAD risk.

Dendritic cells in human atherosclerosis: from circulation to atherosclerotic plaques

Background. Atherosclerosis is a chronic inflammatory disease with atherosclerotic plaques containing inflammatory infiltrates predominantly consisting of monocytes/macrophages and activated T cells. More recent is the implication of dendritic cells (DCs) in the disease. Since DCs were demonstrated in human arteries in 1995, numerous studies in humans suggest a role for these professional antigen-presenting cells in atherosclerosis. Aim. This paper focuses on the observations made in blood and arteries of patients with atherosclerosis. In principal, flow cytometric analyses show that circulating myeloid (m) and plasmacytoid (p) DCs are diminished in coronary artery disease, while immunohistochemical studies describe increased intimal DC counts with evolving plaque stages. Moreover, mDCs and pDCs appear to behave differently in atherosclerosis. Yet, the origin of plaque DCs and their relationship with blood DCs are unknown. Therefore, several explanations for the observed changes are postulated. In addition, the technical challenges and discrepancies in the research field are discussed. Future. Future studies in humans, in combination with experimental animal studies will unravel mechanisms leading to altered blood and plaque DCs in atherosclerosis. As DCs are crucial for inducing but also dampening immune responses, understanding their life cycle, trafficking and function in atherosclerosis will determine potential use of DCs in antiatherogenic therapies.

Anthraquinone Profile, Antioxidant and Antimicrobial Properties of Bark Extracts of Rhamnus catharticus and R. orbiculatus

The anthraquinone profile, antioxidant and antimicrobial activities as well as the total phenol and total flavonoid contents were determined in methanol extracts of the barks of Rhamnus catharticus L. and R. orbiculatus Bornm. The most abundant anthraquinone derivatives in R. catharticus were physcion (67.8%) and emodin (26.2%), while R. orbiculatus contained mostly physcion (81.3%) and chrysophanol (14.6%). R. catharticus displayed better activity in the β-carotene–linoleic acid assay, as well as chelating activity, whereas its activity in the reducing power assay was significantly lower than that of R. orbiculatus. Both methanol extracts showed antimicrobial activity against all microbial species tested ( Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Aspergillus niger, Microsporum gypseum) with MIC values either equal to or lower than 2.50 mg/mL. R. catharticus and R. orbiculatus contained several anthranoid aglycones and their bark extracts demonstrated notable antioxidant and antimicrobial properties. The results obtained indicate the medicinal potential of these two species.

Ligustrazine improves atherosclerosis in rat via attenuation of oxidative stress

CONTEXT

Ligustrazine (Lig) is a compound isolated from the rhizome of Ligusticum chuanxiong Hort. (Umbelliferae) and has been reported to be effective for the treatment of a variety of vascular diseases.

OBJECTIVE

The anti-atherosclerotic activities of Lig are evaluated in vivo for the first time in the present study.

MATERIALS AND METHODS

We gave rats a single injection of vitamin D3 and then fed them with an atherogenic diet for 6 weeks to induce atherosclerosis. Lig was simultaneously given to rats by gavage at the dose of 20 or 80 mg/kg in the therapy groups. Multiple approaches including spectrophotometry, hematoxylin and eosin (H&E) staining, and quantitative RT-PCR were applied to investigate the effects of Lig on blood parameters, aorta and liver histology, and gene expression. In addition, the solely effects of Lig on food intake, body weight gain, and taste preference were also evaluated.

RESULTS

We found that two doses of Lig treatment decreased the total cholesterol levels by 65.2 and 76.7%, respectively, in the plasma. Triglyceride (by 53.2 and 77.9%) and low-density lipoprotein (by 71.2 and 79.0%) levels were also decreased. However, high-density lipoprotein level was slightly increased. The circulating endothelial cells were decreased by 42.2 and 60.0% in Lig-treated rats, indicating the attenuation of endothelial injury. In contrast, Lig restored the total antioxidant capacity and superoxide dismutase 1 (SOD1) activity while decreasing the MDA generation. Furthermore, Lig improved liver dysfunction by decreasing ALT (by 13.0 and 49.7%) and AST (by 10.7 and 14.3%) levels. Histological examinations revealed that Lig suppressed atherosclerotic plaque progression in the thoracic aorta and lipid accumulation in the liver. At the transcriptional level, Lig inhibited the induction of antioxidant genes both in aorta and in liver. Lig also suppressed the mRNA expression of the genes involved in the hepatic fatty acid oxidation. Finally, Lig had a minimum effect on food intake, body weight gain, and taste preference.

DISCUSSION AND CONCLUSION

Our results suggest that Lig suppresses the development of atherosclerosis and hepatic lipid accumulation via the alleviation of oxidative stress and the improvement of dyslipidemia.

Protective effects of aucubin on H₂O₂-induced apoptosis in PC12 cells

The present study investigated the neuroprotective effects of aucubin on hydrogen peroxide (H₂O₂)-induced apoptosis in PC12 cells. Exposure of PC12 cells to 0.25 mm H₂O₂ induced a leakage of lactate dehydrogenase and decreased cell viability, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In a dose over 0.1 mm, aucubin increased PC12 cellular viability and markedly attenuated H₂O₂-induced apoptotic cell death. Quantitation of apoptosis by flow cytometry indicated that aucubin inhibited H₂O₂-induced apoptosis in PC12 cells. Nuclear damage was alleviated by aucubin, as shown by Hoechst staining. In addition, the levels of malondialdehyde were reduced and the activity of superoxide dismutase, catalase and glutathione peroxidase was augmented in these cells. These results indicated that aucubin inhibited H₂O₂-induced apoptosis in PC12 cells through regulation of the endogenous oxidant-antioxidant balance. Our results suggest that aucubin is a potential protective agent for the treatment of oxidative-stress-induced neurodegenerative disease.

Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil

Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin-angiotensin-aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.

Rapeseed oil fortified with micronutrients reduces atherosclerosis risk factors in rats fed a high-fat diet

Background

Micronutrients polyphenols, tocopherols and phytosterols in rapeseed exert potential benefit to cardiovascular system, but most of these micronutrients are removed by the refining process. The aim of this study was to determine the effect of rapeseed oil fortified with these micronutrients on the atherosclerosis risk factors in rats fed a high-fat diet.

Methods

The rodent diet contained 20% fat whose source was refined rapeseed oil (RRO) or fortified refined rapeseed oil with low, middle and high quantities of these micronutrients (L-, M- and H-FRRO). Forty male SD rats were divided into four groups. One group received RRO diet and other groups received L-, M- and H-FRRO diet for 10 weeks.

Results

Micronutrients supplementation significantly increased plasma antioxidant defense capacities, as evaluated by the significant elevation in the activities of GPx, CAT and SOD as well as the level of GSH, and the significant decline in lipid peroxidation. These micronutrients also reduced the plasma contents of TG, TC and LDL-C and increased the ratio of HDL-C/LDL-C. In addition, in parallel with the enhancement of these micronutrients, plasma levels of IL-6 and CRP declined remarkably.

Conclusion

Rapeseed oil fortified with micronutrients polyphenols, tocopherols and phytosterols may contribute to prevent atherogenesis by ameliorating plasma oxidative stress, lipid profile and inflammation.

The simple and sensitive measurement of malondialdehyde in selected specimens of biological origin and some feed by reversed phase high performance liquid chromatography

A method for the determination of malondialdehyde (MDA) concentrations in specimens of animal tissues and feed has been developed using high performance liquid chromatography. The MDA concentration in acidified urine samples was determined after its conversion with 2,4-dinitrophenylhydrazine (DNPH) to a hydrazone (MDA-DNPH). Samples of blood plasma, muscle, liver and feed were prepared by saponification followed by derivatisation with DNPH to MDA-DNPH. The MDA concentration in chicken and hen feed samples was analysed after saponification and derivatisation followed by extractions with hexane. The free MDA in plasma samples was determined after deproteinization followed by derivatisation of MDA with DNPH. The chromatographic separation of MDA-DNPH samples was conducted using Phenomenex C(18)-columns (Synergi 2.5 μm, Hydro-RP, 100 Å, the length of 100mm) with an inner diameter of 2 or 3mm. MDA in processed biological samples was analysed using a linear gradient of acetonitrile in water, and the photodiode detector was set to 307 or 303 nm for detection. The current method that was utilised was based on the high-efficient derivatisation of MDA and was more sensitive compared to previously used methods. The selective and sensitive photodetection of the column effluent was found to be suitable for the routine analysis of MDA in urine, plasma, muscles and liver of animals and some feed samples. Because urine or blood plasma samples can be derivatised in a simple manner, the proposed method can also be suitable for the routine, non-invasive evaluation of oxidative stress in animals and humans.

Antioxidants alleviate nicotine-induced platelet aggregation in cerebral arterioles of mice in vivo

Experimental data on the effect of nicotine on cerebral microvessel thrombosis is lacking. Therefore, this study was carried out to elucidate the effects of nicotine on platelet aggregation in cerebral (pial) microcirculation of the mouse, and the possible protective effect of vitamins C and E. Male TO mice were divided into six groups, and injected i.p. with saline as a control, nicotine (1 mg/kg), vitamin C alone (100 mg/kg), vitamin E alone (100 mg/kg), nicotine plus vitamin C or nicotine plus vitamin E, all for one week before the experiment. After one week, platelet aggregation in cerebral microvessels of these groups of mice were studied in vivo. The appearance of the first platelet aggregation and total blood flow stop in arterioles and venules were timed in seconds. In the animals treated with nicotine, venules did not show any alteration in the platelet aggregation time in comparison to the control animals. However, in arterioles platelet aggregation time was significantly accelerated (p<0.001) in nicotine-treated animals as compared to controls. Both vitamins C and E prevented the shortening of arteriolar platelet aggregation time significantly (p<0.001) when applied with nicotine but not alone. It can be concluded that nicotine enhances the susceptibility to thrombosis in the cerebral arterioles in vivo and that vitamins C and E have alleviating effect on nicotine-induced thrombotic events in mice pial microvessels.

Oxidative modifications of the C-terminal domain of tropoelastin prevent cell binding

Tropoelastin (TE), the soluble monomer of elastin, is synthesized by elastogenic cells, such as chondrocytes, fibroblasts, and smooth muscle cells (SMCs). The C-terminal domain of TE interacts with cell receptors, and these interactions play critical roles in elastic fiber assembly. We recently found that oxidation of TE prevents elastic fiber assembly. Here, we examined the effects of oxidation of TE on cell interactions. We found that SMCs bind to TE through heparan sulfate (HS), whereas fetal lung fibroblasts (WI-38 cells) bind through integrin α(v)β(3) and HS. In addition, we found that oxidation of TE by peroxynitrite (ONOO(-)) prevented binding of SMCs and WI-38 cells and other elastogenic cells, human dermal fibroblasts and fetal bovine chondrocytes. Because the C-terminal domain of TE has binding sites for both HS and integrin, we examined the effects of oxidation of a synthetic peptide derived from the C-terminal 25 amino acids of TE (CT-25) on cell binding. The CT-25 peptide contains the only two Cys residues in TE juxtaposed to a cluster of positively charged residues (RKRK) that are important for cell binding. ONOO(-) treatment of the CT-25 peptide prevented cell binding, whereas reduction of the CT-25 peptide had no effect. Mass spectrometric and circular dichroism spectroscopic analyses showed that ONOO(-) treatment modified both Cys residues in the CT-25 peptide to sulfonic acid derivatives, without altering the secondary structure. These data suggest that the mechanism by which ONOO(-) prevents cell binding to TE is by introducing negatively charged sulfonic acid residues near the positively charged cluster.

Cardiovascular Complications in CKD Patients: Role of Oxidative Stress

Starting with the early stages, patients with chronic kidney disease (CKD) experience higher burden of cardiovascular disease (CVD). Moreover, CVD complications are the major cause of mortality in CKD patients as compared with complications from chronic kidney failure. While traditional CVD risk factors, including diabetes, hypertension, hyperlipidemia, obesity, physical inactivity, may be more prevalent among CKD patients, these factors seem to underestimate the accelerated cardiovascular disease in the CKD population. Search for additional biomarkers that could explain the enhanced CVD risk in CKD patients has gained increasing importance. Although it is unlikely that any single nontraditional risk factor would fully account for the increased CVD risk in individuals with CKD, oxidative stress appears to play a central role in the development and progression of CVD and its complications. We will review the data that support the contribution of oxidative stress in the pathogenesis of CVD in patients with chronic kidney failure.

Copper and myeloperoxidase-modified LDLs activate Nrf2 through different pathways of ROS production in macrophages

Low-density lipoprotein (LDL) oxidation is a key step in atherogenesis, promoting the formation of lipid-laden macrophages. Here, we compared the effects of copper-oxidized LDLs (OxLDLs) and of the more physiologically relevant myeloperoxidase-oxidized LDLs (MoxLDLs) in murine RAW264.7 macrophages and in human peripheral blood monocyte-derived macrophages. Both oxidized LDLs, contrary to native LDLs, induced foam cell formation and an intracellular accumulation of reactive oxygen species (ROS). This oxidative stress was responsible for the activation of the NF-E2-related factor 2 (Nrf2) transcription factor, and the subsequent Nrf2-dependent overexpression of the antioxidant genes, Gclm and HO-1, as evidenced by the invalidation of Nrf2 by RNAi. MoxLDLs always induced a stronger response than OxLDLs. These differences could be partly explained by specific ROS-producing mechanisms differing between OxLDLs and MoxLDLs. Whereas both types of oxidized LDLs caused ROS production partly by NADPH oxidase, only MoxLDLs-induced ROS production was dependent on cytosolic PLA2. This study highlights that OxLDLs and MoxLDLs induce an oxidative stress, through distinct ROS-producing mechanisms, which is responsible for the differential activation of the Nrf2 pathway. These data clearly suggest that results obtained until now with copper oxidized-LDLs should be carefully reevaluated, taking into consideration physiologically more relevant oxidized LDLs.