Free-radical-generated F2-isoprostane stimulates cell proliferation and endothelin-1 expression on endothelial cells

Oxidative Stress in Kidney Injury and Hypertension

Hypertension (HTN) is a major contributor to kidney damage, leading to conditions such as nephrosclerosis and hypertensive nephropathy, significant causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD). HTN is also a risk factor for stroke and coronary heart disease. Oxidative stress, inflammation, and activation of the renin-angiotensin-aldosterone system (RAAS) play critical roles in causing kidney injury in HTN. Genetic and environmental factors influence the susceptibility to hypertensive renal damage, with African American populations having a higher tendency due to genetic variants. Managing blood pressure (BP) effectively with treatments targeting RAAS activation, oxidative stress, and inflammation is crucial in preventing renal damage and the progression of HTN-related CKD and ESRD. Interactions between genetic and environmental factors impacting kidney function abnormalities are central to HTN development. Animal studies indicate that genetic factors significantly influence BP regulation. Anti-natriuretic mechanisms can reset the pressure-natriuresis relationship, requiring a higher BP to excrete sodium matched to intake. Activation of intrarenal angiotensin II receptors contributes to sodium retention and high BP. In HTN, the gut microbiome can affect BP by influencing energy metabolism and inflammatory pathways. Animal models, such as the spontaneously hypertensive rat and the chronic angiotensin II infusion model, mirror human essential hypertension and highlight the significance of the kidney in HTN pathogenesis. Overproduction of reactive oxygen species (ROS) plays a crucial role in the development and progression of HTN, impacting renal function and BP regulation. Targeting specific NADPH oxidase (NOX) isoforms to inhibit ROS production and enhance antioxidant mechanisms may improve renal structure and function while lowering blood pressure. Therapies like SGLT2 inhibitors and mineralocorticoid receptor antagonists have shown promise in reducing oxidative stress, inflammation, and RAAS activity, offering renal and antihypertensive protection in managing HTN and CKD. This review emphasizes the critical role of NOX in the development and progression of HTN, focusing on its impact on renal function and BP regulation. Effective BP management and targeting oxidative stress, inflammation, and RAAS activation, is crucial in preventing renal damage and the progression of HTN-related CKD and ESRD.

Novel Oxidative Stress Biomarkers with Risk Prognosis Values in Heart Failure

Oxidative stress (OS) is mediated by reactive oxygen species (ROS), which in cardiovascular and other disease states, damage DNA, lipids, proteins, other cellular and extra-cellular components. OS is both initiated by, and triggers inflammation, cardiomyocyte apoptosis, matrix remodeling, myocardial fibrosis, and neurohumoral activation. These have been linked to the development of heart failure (HF). Circulating biomarkers generated by OS offer potential utility in patient management and therapeutic targeting. Novel OS-related biomarkers such as NADPH oxidases (sNox2-dp, Nrf2), advanced glycation end-products (AGE), and myeloperoxidase (MPO), are signaling molecules reflecting pathobiological changes in HF. This review aims to evaluate current OS-related biomarkers and their associations with clinical outcomes and to highlight those with greatest promise in diagnosis, risk stratification and therapeutic targeting in HF.

Neck Circumference and Blood Pressure Measurements among Walter Sisulu University Students

Hypertension is a public health problem in South Africa. Increases in subcutaneous fat, presented by the neck circumference (NC) value, contribute to and predict the development of hypertension. However, to date, there has been no study done to investigate the relationship between the NC and blood pressure (BP) among historically disadvantaged university students. Therefore, the aim of the study was to investigate the relationship between the NC and BP among Walter Sisulu University students. This cross-sectional study was conducted in Walter Sisulu University. All 127 students were aged 18 years and above and underwent NC and clinical BP measurements using standard procedures. In a Pearson's correlation analysis, the NC positively correlated with both the systolic blood pressure (SBP) (r = 0.5; p < 0.001) and diastolic blood pressure (DBP) (r = 0.3; p < 0.001). Furthermore, in the multivariable-adjusted regression analysis, the NC was positively associated with both the SBP (adjusted R² = 0.3, β = 2.0 (95% CI = 1.1; 2.9), p < 0.001) and DBP (adjusted R² = 0.1 β = 0.950 (95% CI = 0.3; 1.6), p = 0.008) adjusted for age, gender, body mass index, waist-to-height ratio, alcohol, and smoking. The NC is related to BP among historically disadvantaged university students.

The Link Between 15-F2t-Isoprostane Activity and Acute Bovine Endothelial Inflammation Remains Elusive

Modern dairy cattle suffer from increased incidence and severity of mastitis during major physiological transitions of the lactation cycle. Oxidative stress, a condition resulting from inadequate antioxidant defense against reactive oxygen and nitrogen species, is a major underlying component of mastitis pathophysiology. Isoprostanes (IsoP) are molecules derived from cellular lipid membranes upon non-enzymatic interaction with reactive species during inflammation, and are regarded as highly sensitive and specific biomarkers of oxidative stress. Changes in IsoP concentrations have been noted during major physiological transitions and diseases such as coliform mastitis in dairy cattle. However, the biological role of IsoP during oxidative stress in dairy cows has not been well-elucidated. Therefore, this study aimed to characterize the impacts of IsoP on oxidative stress outcomes in a bovine model of acute endothelial inflammation. Bovine aortic endothelial cells (BAEC; n = 4) were stimulated with 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) or lipopolysaccharide (LPS) with or without 15-F2t-IsoP to determine how IsoP influence oxidative stress outcomes. Our endothelial inflammation model showed relatively decreased reactive metabolites and increased barrier integrity in cells treated with both the agonist and IsoP compared to agonist treatment alone. However, IsoP do not appear to affect oxidative stress outcomes during acute inflammation. Understanding the effect of IsoP on BAEC is an early step in elucidating how IsoP impact dairy cows during times of oxidative stress in the context of acute clinical mastitis. Future studies should define the optimal dosing and treatment timing of IsoP to maximize their cytoprotective potential during acute inflammation.

A Study to Validate the Relevance of Semen F2-Isoprostanes on Human Male Infertility

F₂-isoprostanes (F₂-IsoPs), byproducts of arachidonic acid oxidation, are one of the most reliable indices for assessing lipid peroxidation in vivo. This study aimed at evaluating the seminal F₂-IsoP level in 147 patients with different reproductive conditions (varicocele, urogenital infection, idiopathic infertility) and 45 fertile controls to establish a cut-off value discriminating physiological and pathological ranges. Semen analyses were performed following WHO guidelines; F₂-IsoP levels were measured by gas chromatography/negative-ion chemical ionization tandem mass spectrometry. Considering the whole group of patients, F₂-IsoPs correlated negatively with normal morphology (r = −0.283, p < 0.01), viability (r = −0.245, p < 0.01), total progressive motility (r = −0.309, p < 0.01) and rapid motility (r = −0.535, p < 0.01). The area under the ROC curve for F₂-IsoP levels was 0.839, indicating a good performance of the test; the Youden index showed a cut-off value of 29.96 ng/mL. Fertile men (except one) were distributed in the group of patients with F₂-IsoP level < 29.96 ng/mL. Varicocele and urogenital infection groups showed the highest levels of F₂-IsoPs in semen. For the first time, a cut-off for F₂-IsoPs is identified in human semen. It allows discriminating different male infertility conditions by the semen F₂-IsoP amounts, as an additional parameter for clinical evaluation.

Inflammation and Oxidative Stress in Chronic Kidney Disease and Dialysis Patients

Significance: Chronic kidney disease (CKD) can be regarded as a burden of lifestyle disease that shares common underpinning features and risk factors with the aging process; it is a complex constituted by several adverse components, including chronic inflammation, oxidative stress, early vascular aging, and cellular senescence. Recent Advances: A systemic approach to tackle CKD, based on mitigating the associated inflammatory, cell stress, and damage processes, has the potential to attenuate the effects of CKD, but it also preempts the development and progression of associated morbidities. In effect, this will enhance health span and compress the period of morbidity. Pharmacological, nutritional, and potentially lifestyle-based interventions are promising therapeutic avenues to achieve such a goal. Critical Issues: In the present review, currents concepts of inflammation and oxidative damage as key patho-mechanisms in CKD are addressed. In particular, potential beneficial but also adverse effects of different systemic interventions in patients with CKD are discussed. Future Directions: Senotherapeutics, the nuclear factor erythroid 2-related factor 2-kelch-like ECH-associated protein 1 (NRF2-KEAP1) signaling pathway, the endocrine klotho axis, inhibitors of the sodium-glucose cotransporter 2 (SGLT2), and live bio-therapeutics have the potential to reduce the burden of CKD and improve quality of life, as well as morbidity and mortality, in this fragile high-risk patient group. Antioxid. Redox Signal. 35, 1426-1448.

Role of isoprostanes in human male infertility

One of the major causes of defective sperm function is oxidative stress, which limits the fertilizing potential of these cells as the result of collateral damage to proteins and lipids in the sperm plasma membrane. On this point, a derangement of both generation and neutralization of reactive oxygen species (ROS) is a recognized cause of male infertility. Antioxidant protection in sperm has been widely investigated, as well as the sperm composition of fatty acids (FA), which represents the preferred substrate for ROS, most frequently linked to the disease-related infertility. Isoprostanes are compounds derived from free radical-mediated oxidation of FAs. As such, they are considered an index of lipid oxidative damage and lipid mediators. This article discusses the role of isoprostanes as relevant factors both to sperm FA composition and sperm membrane integrity. Additionally, isoprostane's influence on sperm quality is reviewed. With reference to male reproductive dysfunction, increasing evidence indicates isoprostanes, detectable in biological fluids or sperm membrane, as the specific index of 1) exposure to chemical etiological agents, 2) oxidative damage, 3) reduced antioxidant response, and 4) sperm immaturity.

ABBREVIATIONS

OS: oxidative stress; ROS: reactive oxygen species; PUFAs: polyunsaturated fatty acids; ARA: arachidonic acid, F₂-IsoPs; F₂-isoprostanes, PLA₂: phospholipase A₂; NADPH: nicotinamide adenine dinucleotide phosphate; IVF: in vitro fertilization.

Effect of 1,5-anhydroglucitol levels on culprit plaque rupture in diabetic patients with acute coronary syndrome

BACKGROUND

Postprandial hyperglycemia was reported to play a key role in established risk factors of coronary artery diseases (CAD) and cardiovascular events. Serum 1,5-anhydroglucitol (1,5-AG) levels are known to be a clinical marker of short-term postprandial glucose (PPG) excursions. Low serum 1,5-AG levels have been associated with occurrence of CAD. However, the relationship between 1,5-AG levels and coronary plaque rupture has not been fully elucidated. The aim of this study was to evaluate 1,5-AG as a predictor of coronary plaque rupture in diabetic patients with acute coronary syndrome (ACS).

METHODS

A total of 144 diabetic patients with ACS were included in this study. All patients underwent intravascular ultrasound examination, which revealed 49 patients with plaque rupture and 95 patients without plaque rupture in the culprit lesion. Fasting blood glucose (FBG), hemoglobin A1c (HbA1c) and 1,5-AG levels were measured before coronary angiography. Fasting urinary 8-iso-prostaglandin F2α (8-iso-PGF2α) level was measured and corrected by creatinine clearance.

RESULTS

Patients with ruptured plaque had significantly lower serum 1,5-AG levels, longer duration of diabetes, higher HbA1c and FBG levels than patients without ruptured plaque in our study population. In multivariate analysis, low 1,5-AG levels were an independent predictor of plaque rupture (odds ratio 3.421; P = 0.005) in diabetic patients with ACS. The area under the receiver-operating characteristic curve for 1,5-AG (0.658, P = 0.002) to predict plaque rupture was superior to that for HbA1c (0.587, P = 0.087). Levels of 1,5-AG were significantly correlated with urinary 8-iso-prostaglandin F2α levels (r = - 0.234, P = 0.005).

CONCLUSIONS

Serum 1,5-AG may identify high risk for coronary plaque rupture in diabetic patients with ACS, which suggests PPG excursions are related to the pathogenesis of plaque rupture in diabetes.

Association of Isoprostanes-Related Oxidative Stress with Vulnerability of Culprit Lesions in Diabetic Patients with Acute Coronary Syndrome

Urinary excretion of 8-iso-prostaglandin F2α (8-iso-PGF2α), a reliable biomarker for enhanced oxidant stress in vivo, has been described in association with diabetes and coronary heart disease. The aim of this study was to evaluate the relationship between urinary 8-iso-PGF2α levels and the characteristics of coronary culprit lesion in diabetic patients with acute coronary syndrome (ACS). A total of 79 diabetic patients with ACS were included. iMAP intravascular ultrasound (iMAP-IVUS) was performed to evaluate the characteristics of culprit plaques. Fasting urinary 8-iso-PGF2α level was measured and corrected by creatinine clearance. iMAP-IVUS data showed culprit plaques in high urinary 8-iso-PGF2α level patients had a greater percentage of necrotic core and less fibrous components. High urinary 8-iso-PGF2α levels were correlated with increased necrotic plaque components (r = 0.325, P = 0.003). Meanwhile, the presence of thin-capped fibroatheroma (50.0% versus 11.5%, P = 0.003), ruptured plaques (30.8% versus 7.7%, P = 0.035), and thrombus (38.5% versus 7.7%, P = 0.008) were significantly more frequent in the upper tertile of urinary 8-iso-PGF2α levels than in the low tertile. Multivariate analysis showed high levels of urinary 8-iso-PGF2α (OR 4.240, P = 0.007) was independently associated with the presence of vulnerable culprit plaque in diabetic ACS patients. Urinary 8-iso-PGF2α also displayed a significant value in predicting vulnerable plaques in diabetic patients with ACS by constructing the receiver-operating characteristic (ROC) curve (Area under the ROC curve: 0.713, P = 0.001). Urinary 8-iso-PGF2α levels are associated with the vulnerability of the coronary culprit lesion in diabetic patients with ACS and may provide additional information for risk assessment in suspected vulnerable patients.

Urinary 8-iso-prostaglandin F2α as a risk marker for the vulnerability of culprit plaque in diabetic patients with stable coronary artery disease

We evaluated the association of urinary excretion of 8-iso-prostaglandin F2α (8-iso-PGF2α) with the vulnerability of culprit lesions in 156 age- and sex-matched diabetic stable coronary artery disease (CAD) patients with or without thin-capped fibroatheroma (TCFA) identified by iMAP intravascular ultrasound. Fasting urinary 8-iso-PGF2α level was measured and corrected by creatinine clearance. Compared to non-TCFA group, patients with TCFA had higher urinary 8-iso-PGF2α levels [114.6 (71.1, 181.5) vs. 83.0 (63.2, 138.2) pmol/mmolCr, P = 0.012]. Urinary 8-iso-PGF2α level was positively correlated with percent necrotic volume of culprit lesion (r = 0.218, P = 0.006). High urinary 8-iso-PGF2α level (OR 2.941, P = 0.009) was independently associated with the presence of TCFA and displayed a significant value in predicting TCFA plaques in study patients. The current study indicated that urinary 8-iso-PGF2α may be an important surrogate marker for the vulnerability of culprit lesion in diabetic patients with CAD.

Isoprostane in systemic sclerosis: A systematic review and meta-analysis

OBJECTIVES

To further the knowledge of oxidative stress in systemic sclerosis (SSc), we performed a systematic review and meta-analysis on studies measuring isoprostane, a vasoactive agent deriving from arachidonic acid and implicated in the vasculopathy of SSc.

METHODS

Systematic search following the PRISMA guidelines in PubMed and EMBASE between January-1990/December-2017 using the terms: oxidative stress, isoprostane, systemic sclerosis and scleroderma.

RESULTS

After the screening process, 8 studies including 240 SSc patients and 192 controls were included in the systematic review and meta-analysis, 6 investigating urinary and 2 serum isoprostane: random effect meta-analysis revealed isoprostane overgeneration in SSc (p < .001) with wide heterogeneity (I² = 75%). Subgroup analysis on urinary isoprostane favoured excess excretion in SSc (p = .009) with slightly lower heterogeneity (I² = 67%); further subgroup analysis according to unit of measurement revealed no increased isoprostane excretion when expressed as pg/mg creatinine but increased when expressed as pmol/mmol creatinine (p = .05) with medium heterogeneity (I² = 32%). Subgroup analysis on serum isoprostane favoured overproduction in SSc (p < .0001) with no heterogeneity.

CONCLUSION

There is some evidence for isoprostane overgeneration in SSc that confirms the occurrence of oxidative stress in this setting: further prospective studies with specified outcomes are needed to evaluate the prognostic value of this functional biomarker.

Biological activities of non-enzymatic oxygenated metabolites of polyunsaturated fatty acids (NEO-PUFAs) derived from EPA and DHA: New anti-arrhythmic compounds?

ω3 Polyunsaturated fatty acids (ω3 PUFAs) have several biological properties including anti-arrhythmic effects. However, there are some evidences that it is not solely ω3 PUFAs per se that are biologically active but the non-enzymatic oxygenated metabolites of polyunsaturated fatty acids (NEO-PUFAs) like isoprostanes and neuroprostanes. Recent question arises how these molecules take part in physiological homeostasis, show biological bioactivities and anti-inflammatory properties. Furthermore, they are involved in the circulations of childbirth, by inducing the closure of the ductus arteriosus. In addition, oxidative stress which can be beneficial for the heart in given environmental conditions such as the presence of ω3 PUFAs on the site of the stress and the signaling pathways involved are also explained in this review.

Modulation of oxidative stress response by flaxseed oil: Role of lipid peroxidation and underlying mechanisms

Polyunsaturated fatty acids (PUFA's) are majorly classified as ω-3 and ω-6 fatty acids. The eicosapentaenoic acid (EPA, ω-3:20-5), docosahexaenoic acid (DHA, ω-3:22-6) and alpha-linolenic acid (ALA, ω-3:18-3) are known ω-3 fatty acids, extracted from animal (e.g fish oil) and plant sources (e.g flaxseed oil). Furthermore, linoleic acid (LA, ω-6:18-2) is recognized as ω-6 fatty acid and the most prominent biological fatty acid with a pro-inflammatory response. Flaxseed oil has variety of biological roles, due to the significant amount of ω-3/ω-6 fatty acids. Numerous studies have reported that ALA (ω-3:18-3) and LA (ω-6:18-2) has diverse pharmacological activities. The ALA (ω-3:18-3) and LA (ω-6:18-2) are recognised to be the pharmacological antagonist. For example, ALA (ω-3:18-3) is recognised as anti-inflammatory, whereas LA (ω-6:18-2) is considered to be pro-inflammatory. PUFA's get oxidized in three ways; firstly, free radical-mediated pathway, secondly non-free radical non-enzymatic metabolism, and lastly enzymatic degradation. The present report is an attempt to summarize various modes of PUFA's metabolism and elaborate biological effects of the associated metabolites concerning flaxseed oil.

Bioactive lipids derived from arachidonic acid metabolism in different types of renal replacement therapy

INTRODUCTION

Metabolism and plasma concentration of lipids and lipid-derived compounds play an important role in kidney physiology and pathological processes. The component of membrane phospholipids - arachidonic acid (AA) and its active derivatives - eicosanoids are involved in the development of hypertension, diabetes, inflammation and may contribute to progression of chronic kidney disease (CKD). The purpose of the study was to determine, whether the type of renal replacement therapy has an effect on eicosanoids metabolism.

MATERIALS AND METHODS

The study included 145 patients with CKD: on conservative treatment (n=68), on peritoneal dialysis (PD) (n=23) and undergoing chronic haemodialysis (HD) (n=54). The concentrations of TXB₂, 20-HETE, 8-epi-PGF_2α in platelet poor plasma (PPP) were determined using the ELISA method and 5-HETE, 12-HETE, 15-HETE were measured using the RP-HPLC.

RESULTS

The concentrations of TXB₂ in HD group, both before (2.28±0.72ng/mL) and after (1.49±0.63ng/mL) haemodialysis treatment differed significantly from PD group (57.76±6.13ng/mL). Haemodialysis session led to the significant decrease in TXB₂ plasma concentration (p=0.046). 20-HETE concentrations in HD group (113.55±107.54pg/mL and 199.54±142.98pg/mL before and after haemodialysis, respectively) were significantly higher than in CKD 3-5 group (8.96±12.66pg/mL) and PD group (47.78±34.07pg/mL). The highest concentration of 12-HETE was obtained in PD patients (3.58±3.99ng/mL) and differed significantly from HD group after haemodialysis (0.97±0.28ng/mL) and CKD3-5 group (1.06±0.52ng/mL). The concentrations of 5-HETE, 15-HETE and 8-epi-PGF_2α-III did not differ significantly among examined groups.

CONCLUSIONS

The concentrations of active AA metabolites depend on the mode of renal replacement therapy and are associated with intensity of oxidative stress. They might be considered as potential indicators of kidney damage.

Modified Lipids and Lipoproteins in Chronic Kidney Disease: A New Class of Uremic Toxins

Chronic kidney disease (CKD) is associated with an enhanced oxidative stress and deep modifications in lipid and lipoprotein metabolism. First, many oxidized lipids accumulate in CKD and were shown to exert toxic effects on cells and tissues. These lipids are known to interfere with many cell functions and to be pro-apoptotic and pro-inflammatory, especially in the cardiovascular system. Some, like F2-isoprostanes, are directly correlated with CKD progression. Their accumulation, added to their noxious effects, rendered their nomination as uremic toxins credible. Similarly, lipoproteins are deeply altered by CKD modifications, either in their metabolism or composition. These impairments lead to impaired effects of HDL on their normal effectors and may strongly participate in accelerated atherosclerosis and failure of statins in end-stage renal disease patients. This review describes the impact of oxidized lipids and other modifications in the natural history of CKD and its complications. Moreover, this review focuses on the modifications of lipoproteins and their impact on the emergence of cardiovascular diseases in CKD as well as the appropriateness of considering them as actual mediators of uremic toxicity.

Elevated 8-Isoprostane Levels in Basal Cell Carcinoma and in Uva Irradiated Skin

Isoprostanes are prostaglandin isomers produced from the peroxidation of polyunsaturated fatty acids from the cellular membrane. They have been used as a specific index of cellular lipoperoxidation and as an indirect measure of oxidative stress. However, these molecules also present several biological activities. An oxidative environment measured as the presence of other indirect measurements of reactive oxygen species lipoperoxidation has recently been described in basal cell carcinoma, the most frequent type of non-melanoma skin cancer. This study aims to measure the levels of 8-isoprostaglandin F2α, an isoprostane widely studied in other models as a by-product of ROS-induced lipid peroxidation, in basal cell carcinoma and in UVA irradiated healthy skin. We found that 8-iso-PGF2α is present in higher levels in BCC specimens compared to healthy non sun-exposed skin, confirming previous studies on the production of lipoperoxidation in this tumor. Moreover, we demonstrated that topical pre-treatment with a compound containing vitamin E is capable of reducing 8-iso-PGF2α formation in UV irradiated skin suggesting a role for isoprostanes in UV induced inflammation and eventually carcinogenesis and confirming the function of vitamin E as an antioxidant in this model.

Cirrhosis induces apoptosis in renal tissue through intracellular oxidative stress

BACKGROUND

Renal failure is a frequent and serious complication in patients with decompensated cirrhosis.

OBJECTIVES

We aimed to evaluate the renal oxidative stress, cell damage and impaired cell function in animal model of cirrhosis.

METHODS

Secondary biliary cirrhosis was induced in rats by ligation of the common bile duct. We measured TBARS, ROS and mitochondrial membrane potential in kidney as markers of oxidative stress, and activities of the antioxidant enzymes. Relative cell viability was determined by trypan blue dye-exclusion assay. Annexin V-PE was used with a vital dye, 7-AAD, to distinguish apoptotic from necrotic cells and comet assay was used for determined DNA integrity in single cells.

RESULTS

In bile duct ligation animals there was significant increase in the kidney lipoperoxidation and an increase of the level of intracellular ROS. There was too an increase in the activity of all antioxidant enzymes evaluated in the kidney. The percentage viability was above 90% in the control group and in bile duct ligation was 64.66% and the dominant cell death type was apoptosis. DNA damage was observed in the bile duct ligation. There was a decreased in the mitochondrial membrane potential from 71.40% ± 6.35% to 34.48% ± 11.40% in bile duct ligation.

CONCLUSIONS

These results indicate that intracellular increase of ROS cause damage in the DNA and apoptosis getting worse the renal function in cirrhosis.

Pathophysiology of isoprostanes in the cardiovascular system: implications of isoprostane-mediated thromboxane A2 receptor activation

Isoprostanes are free radical-catalysed PG-like products of unsaturated fatty acids, such as arachidonic acid, which are widely recognized as reliable markers of systemic lipid peroxidation and oxidative stress in vivo. Moreover, activation of enzymes, such as COX-2, may contribute to isoprostane formation. Indeed, formation of isoprostanes is considerably increased in various diseases which have been linked to oxidative stress, such as cardiovascular disease (CVD), and may predict the atherosclerotic burden and the risk of cardiovascular complications in the latter patients. In addition, several isoprostanes may directly contribute to the functional consequences of oxidant stress via activation of the TxA2 prostanoid receptor (TP), for example, by affecting endothelial cell function and regeneration, vascular tone, haemostasis and ischaemia/reperfusion injury. In this context, experimental and clinical data suggest that selected isoprostanes may represent important alternative activators of the TP receptor when endogenous TxA2 levels are low, for example, in aspirin-treated individuals with CVD. In this review, we will summarize the current understanding of isoprostane formation, biochemistry and (patho) physiology in the cardiovascular context.

HO-1 Upregulation Attenuates Adipocyte Dysfunction, Obesity, and Isoprostane Levels in Mice Fed High Fructose Diets

Background. Fructose metabolism is an unregulated metabolic pathway and excessive fructose consumption is known to activate ROS. HO-1 is a potent antioxidant gene that plays a key role in decreasing ROS and isoprostanes. We examined whether the fructose-mediated increase in adipocyte dysfunction involves an increase in isoprostanes and that pharmacological induction of HO-1 would decrease both isoprostane levels and adipogenesis. Methods and Results. We examined the effect of fructose, on adipogenesis in human MSCs in the presence and absence of CoPP, an inducer of HO-1. Fructose increased adipogenesis and the number of large lipid droplets while decreasing the number of small lipid droplets (P < 0.05). Levels of heme and isoprostane in fructose treated MSC-derived adipocytes were increased. CoPP reversed these effects and markedly increased HO-1 and the Wnt signaling pathway. The high fructose diet increased heme levels in adipose tissue and increased circulating isoprostane levels (P < 0.05 versus control). Fructose diets decreased HO-1 and adiponectin levels in adipose tissue. Induction of HO-1 by CoPP decreased isoprostane synthesis (P < 0.05 versus fructose). Conclusion. Fructose treatment resulted in increased isoprostane production and adipocyte dysfunction, which was reversed by the increased expression of HO-1.

CSF isoprostane levels are a biomarker of oxidative stress in multiple sclerosis

Objective:

To investigate the potential of 8-iso-prostaglandin F_2α (8-iso-PGF_2α) as a biomarker for disease activity and oxidative stress in the CSF of patients with multiple sclerosis (MS).

Methods:

The isoprostane 8-iso-PGF_2α is an established biomarker for in vivo oxidative stress and lipid peroxidation. We measured CSF 8-isoPGF_2α levels in 231 patients with MS (74 with relapsing-remitting MS, 67 with primary progressive MS, and 90 with secondary progressive MS [SPMS]) and 40 controls using a competition ELISA.

Results:

We found increased CSF levels of 8-iso-PGF_2α in patients with MS compared to controls, with the most striking values in a subgroup of patients with SPMS. Furthermore, the increase in 8-iso-PGF_2α correlated with other parameters of lipid peroxidation as well as with a decrease in the total antioxidant status in the MS CSF samples.

Conclusions:

Our study demonstrates that CSF levels of 8-iso-PGF_2α may serve as a biomarker of oxidative stress in MS. Further investigation will help establish the pathologic and clinical significance of our preliminary findings.

Signaling pathways involved in isoprostane-mediated fibrogenic effects in rat hepatic stellate cells

Despite evidence supporting a potential role for F2-isoprostanes (F2-IsoP's) in liver fibrosis, their signaling mechanisms are poorly understood. We have previously provided evidence that F2-IsoP's stimulate hepatic stellate cell (HSC) proliferation and collagen hyperproduction by activation of a modified form of isoprostane receptor homologous to the classic thromboxane receptor (TP). In this paper, we examined which signal transduction pathways are set into motion by F2-IsoP's to exert their fibrogenic effects. HSCs were isolated from rat liver, cultured to their activated myofibroblast-like phenotype, and then treated with the isoprostane 15-F2t-isoprostane (15-F2t-IsoP). Inositol trisphosphate (IP3) and adenosine 3',5'-cyclic monophosphate (cAMP) levels were determined using commercial kits. Mitogen-activated protein kinase (MAPK) and cyclin D1 expression was assessed by Western blotting. Cell proliferation and collagen synthesis were determined by measuring [(3)H]thymidine and [(3)H]proline incorporation, respectively. 15-F2t-IsoP elicited an activation of extracellular-signal-regulated kinase (ERK), p38 MAPK, and c-Jun NH2-terminal kinase (JNK), which are known to be also regulated by G-protein-coupled receptors. Preincubation with specific ERK (PD98059), p38 (SB203580), or JNK (SP600125) inhibitors prevented 15-F2t-IsoP-induced cell proliferation and collagen synthesis. 15-F2t-IsoP decreased cAMP levels within 30 min, suggesting binding to the TPβ isoform and activation of Giα protein. Also, 15-F2t-IsoP increased IP3 levels within a few minutes, suggesting that the Gq protein pathway is also involved. In conclusion, the fibrogenic effects of F2-IsoP's in HSCs are mediated by downstream activation of MAPKs, through TP binding that couples via both Gqα and Giα proteins. Targeting TP receptor, or its downstream pathways, may contribute to preventing oxidative damage in liver fibrosis.

Isoprostane and isofuran lipid mediators accumulate in stored red blood cells and influence platelet function in vitro

BACKGROUND

Stored red blood cells (RBCs) release hemoglobin (Hb) that leads to oxidative damage, which may contribute to thrombosis in susceptible transfusion recipients. Oxidative stress stimulates the generation of a new class of lipid mediators called F2 -isoprostanes (F2 -IsoPs) and isofurans (IsoFs) that influence cellular behavior. This study investigated RBC-derived F2 -IsoPs and IsoFs during storage and their influence on human platelets (PLTs).

STUDY DESIGN AND METHODS

F2 -IsoP and IsoF levels in RBC supernatants were measured by mass spectrometry during storage and after washing. The effects of stored supernatants, cell-free Hb, or a key F2 -IsoP, 8-iso-prostaglandin F2α (PGF2α ), on PLT function were examined in vitro.

RESULTS

F2 -IsoPs, IsoFs, and Hb accumulated in stored RBC supernatants. Prestorage leukoreduction reduced supernatant F2 -IsoPs and IsoFs levels, which increased again over storage time. Stored RBC supernatants and 8-iso-PGF2α induced PLT activation marker CD62P (P-selectin) expression and prothrombotic thromboxane A2 release. Cell-free Hb did not alter PLT mediator release, but did inhibit PLT spreading. Poststorage RBC washing reduced F2 -IsoP and IsoF levels up to 24 hours.

CONCLUSIONS

F2 -IsoPs and IsoFs are produced by stored RBCs and induce adverse effects on PLT function in vitro, supporting a potential novel role for bioactive lipids in adverse transfusion outcomes. F2 -IsoP and IsoF levels could be useful biomarkers for determining the suitability of blood components for transfusion. A novel finding is that cell-free Hb inhibits PLT spreading and could adversely influence wound healing. Poststorage RBC washing minimizes harmful lipid mediators, and its use could potentially reduce transfusion complications.

Oxidative stress and increased formation of vasoconstricting F2-isoprostanes in patients with reversible cerebral vasoconstriction syndrome

The pathophysiology of reversible cerebral vasoconstriction syndrome (RCVS) is unknown. Oxidative stress is detrimental to endothelial function and vascular reactivity. We hypothesized that the oxidative stress marker 8-iso-prostaglandin F2α, which is also a potent vasoconstrictor, might contribute to the pathogenesis of RCVS. Recruited participants included 103RCVS patients, 53 patients with primary headache with acute severe attacks, and 54 healthy controls. Subjects recruited prior to 2009 were discovery cohort, whereas those after 2009, replication cohort. Urine samples were obtained from all patients at registration and from 79 patients with RCVS again at remission stage. Urine 8-iso-prostaglandin F2α was analyzed by liquid chromatography-tandem mass spectrometry. Patients with RCVS received magnetic resonance angiography and transcranial color-coded sonography. In RCVS patients, the urine 8-iso-prostaglandin F2α level was higher than that in the other groups in discovery, replication, and combined cohorts (RCVS, 0.29±0.18; primary headache with acute severe attacks, 0.21±0.19; control, 0.18±0.09ng/mg creatinine; P<0.001), and it was positively correlated with the flow velocities of major intracranial arteries, especially within the first week of disease onset (middle cerebral artery, Spearman's correlation coefficient [rs]=0.580, P=0.002; anterior cerebral artery, rs=0.472, P=0.042; posterior cerebral artery, rs=0.457, P=0.022; basilar artery, rs= 0.530, P=0.002). The 8-iso-prostaglandin F2α level decreased from the ictalto remission stage in RCVS patients (0.31±0.21 vs 0.16±0.10ng/mg creatinine, P<0.001). 8-Iso-prostaglandin F2α was higher in patients with RCVS and correlated with the severity of vasoconstrictions. Further studies are required to explore its potential pathogenic role.

Isoprostanes and 4-hydroxy-2-nonenal: markers or mediators of disease? Focus on Rett syndrome as a model of autism spectrum disorder

Lipid peroxidation, a process known to induce oxidative damage to key cellular components, has been implicated in several diseases. Following three decades of explorations mainly on in vitro models reproducible in the laboratories, lipid peroxidation has become increasingly relevant for the interpretation of a wide range of pathophysiological mechanisms in the clinical setting. This cumulative effort has led to the identification of several lipid peroxidation end-products meeting the needs of the in vivo evaluation. Among these different molecules, isoprostanes and 4-hydroxy-2-nonenal protein adducts appear to be particularly interesting. This review shows how specific oxidation products, deriving from polyunsaturated fatty acids precursors, are strictly related to the clinical manifestations and the natural history of Rett syndrome, a genetically determined neurodevelopmental pathology, currently classified among the autism spectrum disorders. In our experience, Rett syndrome offers a unique setting for physicians, biologists, and chemists to explore the borders of the lipid mediators concept.

Isoprostanes and neuroprostanes: total synthesis, biological activity and biomarkers of oxidative stress in humans

Isoprostanes (IsoPs) and neuroprostanes (NeuroPs) are formed in vivo by a free radical non-enzymatic mechanism involving peroxidation of arachidonic acid (AA, C20:4 n-6) and docosahexaenoic acid (DHA, C22:6 n-3) respectively. This review summarises our research in the total synthesis of these lipid metabolites, as well as their biological activities and their utility as biomarkers of oxidative stress in humans.

The heme oxygenase system selectively enhances the anti-inflammatory macrophage-M2 phenotype, reduces pericardial adiposity, and ameliorated cardiac injury in diabetic cardiomyopathy in Zucker diabetic fatty rats

Cardiac function is adversely affected by pericardial adiposity. We investigated the effects of the heme oxygenase (HO) inducer, hemin on pericardial adiposity, macrophage polarization, and diabetic cardiopathy in Zucker diabetic fatty rats (ZDFs) with use of echocardiographic, quantitative real-time polymerase chain reaction, Western immunoblotting, enzyme immunoassay, and spectrophotometric analysis. In ZDFs, hemin administration increased HO activity; normalized glycemia; potentiated insulin signaling by enhancing insulin receptor substrate 1(IRS-1), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (PKB)/Akt; suppressed pericardial adiposity, cardiac hypertrophy, and left ventricular longitudinal muscle fiber thickness, a pathophysiological feature of cardiomyocyte hypertrophy; and correspondingly reduced systolic blood pressure, total peripheral resistance, and pro-inflammatory/oxidative mediators, including nuclear factor κB (NF-κB), cJNK, c-Jun-N-terminal kinase (cJNK), endothelin (ET-1), tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-1β, activating protein 1 (AP-1), and 8-isoprostane, whereas the HO inhibitor, stannous mesoporphyrin, nullified the effects. Furthermore, hemin reduced the pro-inflammatory macrophage M1 phenotype, but enhanced the M2 phenotype that dampens inflammation. Because NF-κB activates TNFα, IL-6, and IL-1β and TNF-α, cJNK, and AP-1 impair insulin signaling, the high levels of these cytokines in obesity/diabetes would create a vicious cycle that, together with 8-isoprostane and ET-1, exacerbates cardiac injury, compromising cardiac function. Therefore, the concomitant reduction of pro-inflammatory cytokines and macrophage infiltration coupled to increased expressions of IRS-1, PI3K, and PKB may account for enhanced glucose metabolism and amelioration of cardiac injury and function in diabetic cardiomyopathy. The hemin-induced preferential polarization of macrophages toward anti-inflammatory macrophage M2 phenotype in cardiac tissue with concomitant suppression of pericardial adiposity in ZDFs are novel findings. These data unveil the benefits of hemin against pericardial adiposity, impaired insulin signaling, and diabetic cardiomyopathy and suggest that its multifaceted protective mechanisms include the suppression of inflammatory/oxidative mediators.

Glucagon-like peptide-1 preserves coronary microvascular endothelial function after cardiac arrest and resuscitation: potential antioxidant effects

Glucagon-like peptide-1 (GLP-1) has protective effects in the heart. We hypothesized that GLP-1 would mitigate coronary microvascular and left ventricular (LV) dysfunction if administered after cardiac arrest and resuscitation (CAR). Eighteen swine were subjected to ventricular fibrillation followed by resuscitation. Swine surviving to return of spontaneous circulation (ROSC) were randomized to receive an intravenous infusion of either human rGLP-1 (10 pmol·kg(-1)·min(-1); n = 8) or 0.9% saline (n = 8) for 4 h, beginning 1 min after ROSC. CAR caused a decline in coronary flow reserve (CFR) in control animals (pre-arrest, 1.86 ± 0.20; 1 h post-ROSC, 1.3 ± 0.05; 4 h post-ROSC, 1.25 ± 0.06; P < 0.05). GLP-1 preserved CFR for up to 4 h after ROSC (pre-arrest, 1.31 ± 0.17; 1 h post-ROSC, 1.5 ± 0.01; 4 h post-ROSC, 1.55 ± 0.22). Although there was a trend toward improvement in LV relaxation in the GLP-1-treated animals, overall LV function was not consistently different between groups. 8-iso-PGF(2α), a measure of reactive oxygen species load, was decreased in post-ROSC GLP-1-treated animals [placebo, control (NS): 38.1 ± 1.54 pg/ml; GLP-1: 26.59 ± 1.56 pg/ml; P < 0.05]. Infusion of GLP-1 after CAR preserved coronary microvascular and LV diastolic function. These effects may be mediated through a reduction in oxidative stress.

Structure-activity relationship of resveratrol and its analogue, 4,4'-dihydroxy-trans-stilbene, toward the endothelin axis in human endothelial cells

Resveratrol inhibits endothelin-1, a vascular tension regulator. We synthesized the resveratrol analogue 4,4'-dihydroxy-trans-stilbene with 2 hydroxyl groups in the 4 and 4' position to obtain a molecule more active than resveratrol (3,4',5-trihydroxy-trans-stilbene). The results demonstrate that 4,4'-dihydroxy-trans-stilbene led to a significant decrease in total endothelin-1 secretion and in endothelin-1 messenger RNA (mRNA) levels in human endothelial cells. In addition, resveratrol and its analogue decreased endothelin-converting enzyme-1 mRNA levels and further reduced the activity of the enzyme. 4,4'-dihydroxy-trans-stilbene was more active than resveratrol because the new molecule exerted greater activity at the level of endothelin synthesis and conversion, even at a lower concentration. Although 4,4'-dihydroxy-trans-stilbene and resveratrol inhibited formation of reactive oxygen species and lipid peroxidation, the treatment of cells with different oxidant agents did not modify the endothelin-1 release. This finding suggests that the inhibition of endothelin-1 secretion is independent of the antioxidant properties of the 2 compounds. On the basis of these results, the resveratrol analogue 4,4'-dihydroxy-trans-stilbene could be a promising chemopreventive agent against cardiovascular diseases.

Atherosclerosis in primary antiphospholipid syndrome

Antiphospholipid syndrome (APS) is the most common cause of acquired thrombophilia, but experimental and clinical evidence accumulated over the years suggest that the clinical manifestations of APS go beyond those of a simple hypercoagulable state. Although still a controversial topic, the elevated risk of atherosclerosis in systemic lupus erythematosus seems little accounted for by the presence of antiphospholipid antibodies, whereas premature atherosclerosis has been addressed in few series of patients with primary APS. The available data in primary APS suggest that traditional risk factors for atherosclerosis are less involved in arterial disease, rather antiphospholipid antibodies appear as major players. Their effect on the coagulation system, the vessel wall and on the antioxidant/oxidant balance impairs vascular homeostasis, leading to premature arterial thickening.

Endothelin activation of reactive oxygen species mediates stress-induced pressor response in Dahl salt-sensitive prehypertensive rats

Experiments were designed to test the hypothesis that endothelin (ET) and/or reactive oxygen species contribute to the pressor response induced by acute air jet stress in normotensive Dahl salt-sensitive rats maintained on a normal salt diet (prehypertensive). Mean arterial pressure was chronically monitored by telemetry before and after 3-day treatment with the free radical scavenger 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (Tempol) or ET receptor antagonists ABT-627 (ET A antagonist) or A-182086 (ET A/B antagonist) supplied in the drinking water. Rats were restrained and subjected to pulsatile air jet stress (3 minutes). Plasma samples at baseline and during acute stress were analyzed for 8-isoprostane (measure of reactive oxygen species production) and ET. Neither Tempol nor ET receptor antagonist treatment had an effect on baseline mean arterial pressure or plasma 8-isoprostane. The pressor response to acute stress was accompanied by significant increases in plasma 8-isoprostane and ET. Tempol significantly reduced both the total pressor response (area under the curve) and the stress-mediated increase in plasma 8-isoprostane; conversely, Tempol had no effect on the stress-induced increase in plasma ET. Combined ET(A/B) antagonism, but not selective ET(A) receptor blockade, similarly suppressed the pressor response to stress and stress-mediated rise in 8-isoprostane. Together these results indicate that reactive oxygen species contribute to the pressor response to acute air jet stress. Furthermore, the increase in reactive oxygen species occurs downstream of ET(B) receptor activation.

Endogenous endothelin stimulates cardiac sympathetic afferents during ischaemia

Myocardial ischaemia activates cardiac sympathetic afferents leading to chest pain and reflex cardiovascular responses. Previous studies have shown that a brief period of myocardial ischaemia increases endothelin in cardiac venous plasma draining ischaemic myocardium and that exogenous endothelin excites cutaneous group III and IV sensory nerve fibres. The present study tested the hypothesis that endogenous endothelin stimulates cardiac afferents during ischaemia through direct activation of endothelin A receptors (ET(A)Rs). Nerve activity of single unit cardiac sympathetic afferents was recorded from the left sympathetic chain or rami communicates (T(2)-T(5)) in anaesthetized cats. Single fields of 38 afferents (CV = 0.25-3.86 m s(-1)) were identified in the left or right ventricle with a stimulating electrode. Five minutes of myocardial ischaemia stimulated all 38 cardiac afferents (8 Adelta, 30 C-fibres) and the responses of these 38 afferents to chemical stimuli were further studied in the following protocols. In the first protocol, injection of endothelin 1 (ET-1, 1, 2 and 4 microg) into the left atrium (LA) stimulated seven ischaemically sensitive cardiac afferents in a dose-dependent manner. Second, BQ-123, a selective ET(A)R antagonist, abolished the responses of nine afferents to 2 microg of ET-1 injected into the left atrium and attenuated the ischaemia-related increase in activity of eight other afferents by 51%. In contrast, blockade of ET(B) receptors caused inconsistent responses to exogenous ET-1 as well as to ischaemia. Furthermore, in the absence of ET(A)R blockade, cardiac afferents responded consistently to repeated administration of ET-1 (n = 7) and to recurrent myocardial ischaemia (n = 7). Finally, using an immunocytochemical staining approach, we observed that ET(A) receptors were expressed in cardiac sensory neurons in thoracic dorsal root ganglia. Taken together, these data indicate that endogenous endothelin contributes to activation of cardiac afferents during myocardial ischaemia through direct stimulation of ET(A) receptors likely to be located in the cardiac sensory nervous system.

Adventitial fibroblasts in vascular structure and function: the role of oxidative stress and beyondThis review is one of a selection of papers published in a Special Issue on Oxidative Stress in Health and Disease

The vascular adventitia, defined as the area between the external elastic lamina and the outermost edge of the blood vessel, is composed primarily of fibroblasts and for years was thought to be merely a passive structural support for the blood vessel. Consequently, studies pertaining to the role of the adventitia in regulating vascular function have been far outnumbered by those regarding the vascular endothelium. However, recent work has begun to reveal the dynamic properties of the adventitia. It was therefore the aim of this review to provide an overview of the existing knowledge demonstrating the role of the adventitia in regulating vessel structure and function. The main topics covered in this review include the cellular composition of the adventitia and the role of the adventitia in vascular oxidative stress, vasomotor responses, extracellular matrix protein expression, growth factor expression, and endothelin-1 (ET-1) expression. Recent evidence suggests that the adventitia is a major producer of vascular reactive oxygen species. It displays a distinct response to injury, hypoxia, and pulmonary hypertension, mediating vascular remodelling, repair, and extracellular matrix deposition. It may also play a role in regulating vascular tone. More recently, it has been reported that adventitial fibroblasts can produce ET-1 after Ang II treatment. Additionally, emerging evidence suggests that the adventitia may be a potent source of vasoactive hormones such as growth factors and ET-1, which may regulate vascular structure and function via autocrine or paracrine signalling mechanisms. Despite these findings, many important questions regarding the role of the vascular adventitia remain unanswered, suggesting the need for further research to determine its exact function in health and disease.

Prostaglandins in action indispensable roles of cyclooxygenase-1 and -2 in endothelium-dependent contractions

Endothelium regulates local vascular tone by means of releasing relaxing and contracting factors, of which the latter have been found to be elevated in vascular pathogenesis of hypertension, diabetes, hypercholesterolemia, and aging. Endothelium-derived contracting factors (EDCFs) are mainly metabolites of arachidonic acid generated by cyclooxygenase (COX), as vasodilatations in patients with hypertension, metabolic diseases, or advancing age are improved by acute treatment with COX inhibitor indomethacin. COX is presented in two isoforms, COX-1 and COX-2, with the former regarded as constitutive and the latter mainly expressed upon induction. Experiments with animal models of vascular dysfunctions, however, reveal that both isoforms have similar capacity to participate in endothelium-dependent contractions, with augmented expression and activity. COX-derived prostaglandin (PG) H(2), PGF(2α), PGE(2), prostacyclin (PGI(2)), and thromboxane A(2) (TxA(2)) are the proposed EDCFs that mediate endothelium-dependent contractions via the activation of thromboxane-prostanoid (TP) receptor in various vascular beds from different species. Although COX inhibition seems to be a possible strategy in combating COX-associated vascular complications, the incidence of adverse cardiovascular effects of Vioxx has greatly antagonized this concept. Further review of COX inhibitors is required, especially toward the selectivity of coxibs and whether it directly inhibits prostacyclin synthase activity. Meanwhile, TP receptor antagonism may emerge as a therapeutic alternative to reverse prostanoid-mediated vascular dysregulations.

Cardiovascular consequences when nitric oxide and lipid signaling converge

The identification of nitric oxide ((*)NO) as an endogenously produced free radical mediator of endothelial-dependent relaxation and host defense has fundamentally changed concepts of cell signal transduction. Ligand-receptor oriented paradigms of cell signaling were originally centered on the concept of a high affinity and specific interaction between a ligand and its receptor, resulting in the activation of secondary signaling events such as gene expression or modulation of catalytic protein function. While (*)NO ligation of the heme iron of soluble guanylate cyclase is consistent with this perspective, the readily diffusible and broadly reactive (*)NO is increasingly appreciated to react with a vast array of target molecules that mediate paracrine vasodilator actions, inhibition of thrombosis and neointimal proliferation, and both pro- and antiinflammatory signaling reactions that are not affected by inhibitors of soluble guanylate cyclase. There is an expanding array of functionally significant "off target" collateral reactions mediated by (*)NO that are guanylate cyclase-independent and rather are dictated by anatomic distribution and the formation of secondary (*)NO-derived species. These reactions are a critical element of redox-regulated signaling and are addressed herein in the context of the oxidation of unsaturated fatty acids to vascular and inflammatory signaling mediators. Because of their abundance and the intrinsic reactivity of unsaturated lipid intermediates and eicosanoid metabolism enzymes with (*)NO and other oxides of nitrogen, lipid signaling mechanisms are a significant target for regulation by (*)NO in the vascular compartment. This convergence of (*)NO and lipid signaling pathways thus adds another level of regulation to physiological responses such as vasodilation, thrombosis, and inflammation. Herein, interactions between (*)NO and lipid signaling events are placed in the context of cardiovascular regulation.

Bosentan affects 15-F2t-isoprostane adverse effects on postischemic rat hearts

BACKGROUND

15-F(2t)-isoprostane (IsoP), a marker of reactive oxygen species-induced oxidative stress, is increased after myocardial ischemia and reperfusion. It exerts deleterious effects on postischemic myocardium accompanied with increased release of endothelin-1 (ET-1), a potent vasoconstrictor. We hypothesized that IsoP exacerbates myocardial ischemia-reperfusion injury by stimulating ET-1 production, and that ET-1 blockade can attenuate or prevent these deleterious effects of IsoP.

METHODS

Adult rat hearts were perfused by the Langendorff technique with Krebs-Henseleit solution (KH) at a constant flow rate of 10 mL/min. Global myocardial ischemia was induced by stopping KH perfusion for 40 min followed by 60 min of reperfusion. Hearts were randomized to one of the five groups (n = 8 each): untreated control, treated with IsoP (100 nM), or the ET-1 receptor A/B antagonist bosentan (1 μM) alone or in combination 10 min prior to, during 40 min global ischemia and 15 min of reperfusion, or treated with IsoP as above plus delayed administration of bosentan after 15 min of reperfusion.

RESULTS

Coronary effluent ET-1 concentrations in the IsoP group were higher than those in the control group during ischemia and reperfusion (P < 0.05), which was associated with increased release of cardiac-specific creatine kinase, reduced cardiac contractility during reperfusion, and increased myocardial infarct size (all P < 0.05 versus control). Bosentan administration during early reperfusion exacerbated the IsoP deleterious effects, while delayed administration attenuated it.

CONCLUSION

15-F(2t)-isoprostane-induced ET-1 production during later reperfusion is detrimental to functional recovery of damaged myocardium, while ET-1 increase during early reperfusion seems to improve it.

F(2)-isoprostanes as novel biomarkers for type 2 diabetes: a review

Oxidative stress (OS) has been implicated as one of the major underlying mechanisms behind many acute and chronic diseases. However, the measurement of free radicals or their end products is complicated. Isoprostanes, derived from the non-enzymatic peroxidation of arachidonic acid are now considered to be reliable biomarkers of oxidant stress in the human body. Isoprostanes are involved in many of the human diseases such as type 2 diabetes. In type 2 diabetes elevated levels of F₂-Isoprostanes (F₂-IsoPs) have been observed. The measurement of bioactive F₂-IsoPs levels offers a unique noninvasive analytical tool to study the role of free radicals in physiology, oxidative stress-related diseases, and acute or chronic inflammatory conditions. Measurement of oxidative stress by various other methods lacks specificity and sensitivity. This review aims to shed light on the implemention of F₂-IsoPs measurement as a gold-standard biomarker of oxidative stress in type 2 diabetics.

Chemistry and antihypertensive effects of tempol and other nitroxides

Nitroxides can undergo one- or two-electron reduction reactions to hydroxylamines or oxammonium cations, respectively, which themselves are interconvertible, thereby providing redox metabolic actions. 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol) is the most extensively studied nitroxide. It is a cell membrane-permeable amphilite that dismutates superoxide catalytically, facilitates hydrogen peroxide metabolism by catalase-like actions, and limits formation of toxic hydroxyl radicals produced by Fenton reactions. It is broadly effective in detoxifying these reactive oxygen species in cell and animal studies. When administered intravenously to hypertensive rodent models, tempol caused rapid and reversible dose-dependent reductions in blood pressure in 22 of 26 studies. This was accompanied by vasodilation, increased nitric oxide activity, reduced sympathetic nervous system activity at central and peripheral sites, and enhanced potassium channel conductance in blood vessels and neurons. When administered orally or by infusion over days or weeks to hypertensive rodent models, it reduced blood pressure in 59 of 68 studies. This was accompanied by correction of salt sensitivity and endothelial dysfunction and reduced agonist-evoked oxidative stress and contractility of blood vessels, reduced renal vascular resistance, and increased renal tissue oxygen tension. Thus, tempol is broadly effective in reducing blood pressure, whether given by acute intravenous injection or by prolonged administration, in a wide range of rodent models of hypertension.

Beyond prostaglandins--chemistry and biology of cyclic oxygenated metabolites formed by free-radical pathways from polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs) are important constituents in all organisms. They fulfil many functions, ranging from modulating the structure of membranes to acting as precursors of physiologically important molecules, such as the prostaglandins, which for a long time were the most prominent cyclic PUFA metabolites. However, since the beginning of the 1990s a large variety of cyclic metabolites have been discovered that form under autoxidative conditions in vivo to a much larger extent than do prostaglandins. These compounds--isoprostanes, neuroprostanes, phytoprostanes, and isofurans--proved subsequently to be ubiquitous in nature. They display a wide range of biological activities, and isoprostanes have become the currently most reliable indicators of oxidative stress in humans. In a relatively short time, the structural variety, properties, and applications of the autoxidatively formed cyclic PUFA derivatives have been uncovered.

Imaging the boundaries-innovative tools for microscopy of living cells and real-time imaging

Recently, light microscopy moved back into the spotlight, which is mainly due to the development of revolutionary technologies for imaging real-time events in living cells. It is truly fascinating to see enzymes “at work” and optically acquired images certainly help us to understand biological processes better than any abstract measurements. This review aims to point out elegant examples of recent cell-biological imaging applications that have been developed with a chemical approach. The discussed technologies include nanoscale fluorescence microscopy, imaging of model membranes, automated high-throughput microscopy control and analysis, and fluorescent probes with a special focus on visualizing enzyme activity, free radicals, and protein–protein interaction designed for use in living cells.

Associations of isoprostanes-related oxidative stress with surrogate subclinical indices and angiographic measures of atherosclerosis

OBJECTIVES

Cardiovascular diseases are the most common cause of death in the world. Oxidative stress has been proved to play a role in atherosclerotic diseases and 8-isoprostane is one of the most valid markers of in-vivo oxidative stress. We aimed to investigate the 8-isoprostane levels in relation to surrogate and direct angiographic indexes of atherosclerosis.

METHODS

Urinary 8-isoprostane levels were measured and a B-mode carotid ultrasound examination was performed in 100 consecutive patients scheduled for coronary angiography.

RESULTS

In patients with angiographic coronary artery disease (CAD) urinary 8-isoprostane levels were significantly (P<0.001) higher than in patients without CAD (68.75+/-5.5 vs. 38.27+/-3.7 pg/ml). Moreover, 8-isoprostane levels of patients with increased carotid intima media thickness (CIMT) were higher (P<0.001) than in patients with normal CIMT values (75.12+/-6.4 vs. 38.72+/-2.7 pg/ml). Moreover log(8-isoprostane) levels were significantly correlated with maximum and mean CIMT values (P<0.001) and across univessel and multivessel CAD groups levels of log(8-isoprostane) showed a significantly (P<0.001) increasing trend. Logistic regression analysis revealed that 8-isoprostane levels were an independent predictor for both intima-media thickening and angiographic CAD.

CONCLUSION

These findings indicate that elevated urinary levels of 8-isoprostane are associated with both subclinical atherosclerosis and manifest CAD. The results therefore support the hypothesis that isoprostanes-related oxidative stress is involved in the whole atherosclerotic process.