Oxidative Stress and Myocardial Damage during Elective Percutaneous Coronary Interventions and Coronary AngiographyA Comparison of Blood-borne Isoprostane and Troponin Release

Prostanoids in Cardiac and Vascular Remodeling

Prostanoids are biologically active lipids generated from arachidonic acid by the action of the COX (cyclooxygenase) isozymes. NSAIDs, which reduce the biosynthesis of prostanoids by inhibiting COX activity, are effective anti-inflammatory, antipyretic, and analgesic drugs. However, their use is limited by cardiovascular adverse effects, including myocardial infarction, stroke, hypertension, and heart failure. While it is well established that NSAIDs increase the risk of atherothrombotic events and hypertension by suppressing vasoprotective prostanoids, less is known about the link between NSAIDs and heart failure risk. Current evidence indicates that NSAIDs may increase the risk for heart failure by promoting adverse myocardial and vascular remodeling. Indeed, prostanoids play an important role in modulating structural and functional changes occurring in the myocardium and in the vasculature in response to physiological and pathological stimuli. This review will summarize current knowledge of the role of the different prostanoids in myocardial and vascular remodeling and explore how maladaptive remodeling can be counteracted by targeting specific prostanoids.

Cardioprotective Effect of Acetylsalicylic Acid in the Myocardial Ischemia-Reperfusion Model on Oxidative Stress Markers Levels in Heart Muscle and Serum

Heart failure occurs in increased oxidative stress conditions, which contribute to the progression of pathological changes. Orally or intravenously administered acetylsalicylic acid (ASA, aspirin) is typically used in human patients with acute myocardial ischemia. The study used an experimental porcine ischemia-reperfusion model to evaluate the potential cardioprotective effect of intracoronary administered ASA on myocardial ischemia-reperfusion injury. The cardioprotective effect of ASA was evaluated by measuring selected oxidative stress markers levels in infarcted and non-infarcted myocardium 14 days after the procedure, and three times in serum, before the procedure, during the reperfusion process, and after 14-day recovery. The results showed that intracoronary administrated ASA reduced the oxidative stress. The level of oxidative stress, measured with the non-enzymatic markers total antioxidant capacity (TAC), total oxidative status (TOS), and malondialdehyde (MDA), and the enzymatic markers glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST), in heart tissue was significantly higher in a control group injected with saline. The level of oxidative stress in serum, measured with TAC, TOS, oxidative stress index (OSI), and lipofuscin (LF), was also higher in the control group than in animals injected with ASA. The confirmed cardioprotective effect of intracoronary administered ASA provides the foundation for further studies on ASA intracoronary application, which may lead to the development of a new therapy for the treatment of ischemia-reperfusion complications in humans.

Changes in the Nrf2/Keap1 Ratio and PON1 Concentration in Plasma of Patients Undergoing the Left Main Coronary Artery Stenting

Nuclear factor erythroid 2-related factor2 (Nrf2), together with its inhibitor Kelch-like ECH-associated protein 1 (Keap1), is a crucial regulator of cellular redox response. Nrf2 binds to the antioxidant response element (ARE) present in the DNA sequence of a broad group of antioxidant compounds, including paraoxonase (PON1), inducing their transcription. This study was to answer the question of the effect of temporary ischemia/oxidative stress resulting from the left main stenting via percutaneous coronary intervention (LMPCI) performed in the patients included in this study on the cellular redox balance, which is guarded by the Nrf2/Keap1 interaction. We expected a reflection of the redox imbalance due to reactive oxygen species (ROS) in the change in PON1 concentration observed in the following stages of the study, as well as in total antioxidant capacity (TAC) levels. Our results showed the mobilization of cellular Nrf2/Keap1 team right after the procedure (pre-LMPCI median: 2.532, range: 0.07-11.88; post-LMPCI median: 3.735, range: 0.1545-16.18; 24 h-LMPCI median: 5.596, range: 0.02-49.18), which suggest being the result of oxidative stress that accompanies percutaneous coronary intervention (PCI). The course of Keap1 and Nrf2 concentrations at all stages of the experiment appeared to show that Keap1 shadowed the Nrf2 to switch off its activity after Nrf2 induced the mobilization of the antioxidant response. We observed an increase in PON1 concentration (pre-LMPCI median: 179.3, range: 49.76-6120; post-LMPCI median: 215.7, range: 3.80-2771) and a decrease in the TAC level immediately after PCI (pre-LMPC: $1.008\pm 0.27\text{I}$ , post-LMPCI: $0.8030\pm 0.27$ ). This study design allowed for the first time to analyze the chronology of mechanisms and the relationship between selected parameters reflecting the redox state in patients’ plasma. We may conclude that ischemia induced by the PCI was the source of imbalance in the Nrf2/Keap1 ratio via oxidative stress, and this leads to an increase in PON1 concentration first and, in the next step, the TAC mobilization.

Impact of catheterization on shear-mediated arterial dilation in healthy young men

Purpose

Animal studies have shown that endothelial denudation abolishes vasodilation in response to increased shear stress. Interestingly, shear-mediated dilation has been reported to be reduced, but not abolished, in coronary artery disease (CAD) patients following catheterization. However, it is not known whether this resulted from a priori endothelial dysfunction in this diseased population. In this study, we evaluated shear-mediated dilation following catheterization in healthy young men.

Methods

Twenty-six (age: 24.4 ± 3.8 years, BMI: 24.3 ± 2.8 kg m⁻², VO_2peak: 50.5 ± 8.8 ml/kg/min) healthy males underwent unilateral transradial catheterization. Shear-mediated dilation of both radial arteries was measured using flow-mediated dilation (FMD) pre-, and 7 days post-catheterization.

Results

FMD was reduced in the catheterized arm [9.3 ± 4.1% to 4.3 ± 4.1% (P < 0.001)] post-catheterization, whereas no change was observed in the control arm [8.4 ± 3.8% to 7.3 ± 3.8% (P = 0.168)]. FMD was completely abolished in the catheterized arm in five participants. Baseline diameter (P = 0.001) and peak diameter during FMD (P = 0.035) were increased in the catheterized arm 7 days post-catheterization (baseline: 2.3 ± 0.3 to 2.6 ± 0.2 mm, P < 0.001, peak: 2.5 ± 0.3 to 2.7 ± 0.3 mm, P = 0.001), with no change in the control arm (baseline: 2.3 ± 0.3 to 2.3 ± 0.3 mm, P = 0.288, peak: 2.5 ± 0.3 to 2.5 ± 0.3 mm, P = 0.608).

Conclusion

This is the first study in young healthy individuals with intact a priori endothelial function to provide evidence of impaired shear-mediated dilation following catheterization. When combined with earlier studies in CAD patients, our data suggest the catheterization impairs artery function in humans.

Effects of Catheterization on Artery Function and Health: When Should Patients Start Exercising Following Their Coronary Intervention?

Coronary artery disease (CAD) is a leading cause of death worldwide, and percutaneous transluminal coronary angiography (PTCA) and/or percutaneous coronary intervention (PCI; angioplasty) are commonly used to diagnose and/or treat the obstructed coronaries. Exercise-based rehabilitation is recommended for all CAD patients; however, most guidelines do not specify when exercise training should commence following PTCA and/or PCI. Catheterization can result in arterial dysfunction and acute injury, and given the fact that exercise, particularly at higher intensities, is associated with elevated inflammatory and oxidative stress, endothelial dysfunction and a pro-thrombotic milieu, performing exercise post-PTCA/PCI may transiently elevate the risk of cardiac events. This review aims to summarize extant literature relating to the impacts of coronary interventions on arterial function, including the time-course of recovery and the potential deleterious and/or beneficial impacts of acute versus long-term exercise. The current literature suggests that arterial dysfunction induced by catheterization recovers 4-12 weeks following catheterization. This review proposes that a period of relative arterial vulnerability may exist and exercise during this period may contribute to elevated event susceptibility. We therefore suggest that CAD patients start an exercise training programme between 2 and 4 weeks post-PCI, recognizing that the literature suggest there is a 'grey area' for functional recovery between 2 and 12 weeks post-catheterization. The timing of exercise onset should take into consideration the individual characteristics of patients (age, severity of disease, comorbidities) and the intensity, frequency and duration of the exercise prescription.

Potential Role of Vitamin C Intracoronary Administration in Preventing Cardiac Injury After Primary Percutaneous Coronary Intervention in Patients with ST-Elevation Myocardial Infarction

Objective:

The aim of the present study was to determine the effects of intravenous (IV) and intracoronary administration of Vitamin C on the incidence of periprocedural myocardial injury in patients undergoing primary percutaneous coronary intervention (PCI).

Methods:

In this prospective, double-blind, randomized clinical trial, that was conducted in Tehran Heart Center, Iran, between October 2016 and March 2017, 252 patients undergoing primary PCI were enrolled to receive either 3 g of IV Vitamin C before PCI and 100 mg of intracoronary Vitamin C during PCI in addition to the routine treatment (n = 126) or just the routine treatment (n = 126). Cardiac biomarkers were measured before and then 6 and 12 h postprocedurally. We determined the occurrence of contrast-induced acute kidney injury (CI-AKI), according to the levels of serum creatinine, neutrophil gelatinase-associated lipocalin, and platelet activation biomarker (P-selectin) in a subset of 119 patients before and 6 h after PCI.

Findings:

In the patients who received Vitamin C, the serum levels of troponin T after 12 h and creatine kinase-MB after 6 h were significantly lower than those in the placebo group (P = 0.003 andP = 0.00, respectively). CI-AKI occurred in 6 (4.7%) patients in the study group and 8 (6.3%) patients in the control group; there was no significant reduction in CI-AKI in the study group. In addition, the two groups were statically similar as regards the changes in the level of P-selectin.

Conclusion:

In primary PCI patients, the prophylactic use of IV and intracoronary Vitamin C can confer additional clinical benefits such as cardioprotection.

The enigma ofin vivooxidative stress assessment: isoprostanes as an emerging target

Oxidative stress is believed to be one of the major factors behind several acute and chronic diseases, and may also be associated with ageing. Excess formation of free radicals in miscellaneous body environment may originate from endogenous response to cell injury, but also from exposure to a number of exogenous toxins. When the antioxidant defence system is overwhelmed, this leads to cell damage. However, the measurement of free radicals or their endproducts is tricky, since these compounds are reactive and short lived, and have diverse characteristics. Specific evidence for the involvement of free radicals in pathological situations has been difficult to obtain, partly owing to shortcomings in earlier described methods for the measurement of oxidative stress. Isoprostanes, which are prostaglandin-like bioactive compounds synthesized in vivo from oxidation of arachidonic acid, independently of cyclooxygenases, are involved in many human diseases, and their measurement therefore offers a way to assess oxidative stress. Elevated levels of F₂-isoprostanes have also been seen in the normal human pregnancy, but their physiological role has not yet been defined. Large amounts of bioactive F₂-isoprostanes are excreted in the urine in normal basal situations, with a wide interindividual variation. Their exact role in the regulation of normal physiological functions, however, needs to be explored further. Current understanding suggests that measurement of F₂-isoprostanes in body fluids provides a reliable analytical tool to study oxidative stress-related diseases and experimental inflammatory conditions, and also in the evaluation of various dietary antioxidants, as well as drugs with radical-scavenging properties. However, assessment of isoprostanes in plasma or urine does not necessarily reflect any specific tissue damage, nor does it provide information on the oxidation of lipids other than arachidonic acid.

Laminar lesions in horses with systemic oxidative stress, committed by experimentally induced or naturally occurring gastrointestinal disorders

Abstract: Laminitis in horses can be associated with lesions in multiple organs secondary to sepsis. Twenty-one horses suffering from gastrointestinal disorders were used in the experiment; 7 horses with experimentally induced endotoxemia and intestinal ischaemia, and 14 horses suffering from naturally occurring colic syndrome. Tissue samples of lungs, liver, heart, brain, cerebellum and hoof laminar tissue were collected for histopathological and oxidative stress evaluation using nitrotyrosine and superoxide dismutase (SOD2) immunostaining. The horses were divided into two groups: the non-oxidative lesions group (NOLG), with 7 horses showing weak immunostaining in lungs, liver and kidney, and the oxidative lesions group (OLG), with 14 horses showing immunostaining indicating systemic oxidative stress in multiple organs. The horses from OLG showed increase of laminar lesions and SOD2 immunostaining in multiple organs when compared to the horses from the NOLG. No differences were found ln regard to laminar immunostaining by nitrotyrosine and SOD2 between experimental groups. It was concluded that systemic oxidative stress can be associated with the development of laminar lesions, and that the laminar tissue does not respond to oxidative stress with increase of SOD as occurs in other organs.

Incidence and Predictors of Cardiomyocyte Injury in Elective Coronary Angiography

OBJECTIVE

Coronary angiography is considered to be a safe tool for the evaluation of coronary artery disease and performed in approximately 12 million patients each year worldwide. The aim of our study was to investigate the frequency and predictors of cardiomyocyte injury in patients undergoing elective coronary angiography.

METHODS

A total of 749 consecutive patients who were scheduled to undergo elective coronary angiography were prospectively analyzed. High-sensitivity cardiac troponin T concentrations were measured both before and after elective coronary angiography (without intervention). Acute cardiomyocyte injury was predefined as an absolute increase in high-sensitivity cardiac troponin T of at least 7 ng/L (if also fulfilling a relative change of >20%).

RESULTS

Acute cardiomyocyte injury was observed in 101 patients (13.5%, 95% confidence interval [CI], 11.1-16.2). It was independently associated with aortic valve stenosis (odds ratio [OR], 5.4; 95% CI, 3.0-9.8; P <.001), age (OR, 1.05; 95% CI, 1.02-1.08; P <.001), female sex (OR, 3.5; 95% CI, 1.8-6.8; P <.001), contrast volume (OR, 1.006; 95% CI, 1.001-1.012; P = .019 per 10 mL of contrast volume), documented cardiomyopathy (OR, 2.5; 95% CI, 1.0-6.0; P = .045), and mitral regurgitation (OR, 2.3; CI, 1.0-4.9; P = .033). In contrast, operator experience and extent of coronary artery disease were not found to be associated with acute cardiomyocyte injury.

CONCLUSIONS

Cardiomyocyte injury accompanies elective coronary angiography in 1 of 8 patients. Sex, age, contrast agent volume, and ventricular disease, rather than the extent of coronary artery disease, independently predict cardiomyocyte injury. Further research aiming to reduce the incidence of cardiomyocyte injury seems warranted.

Oxidative stress in hoof laminar tissue of horses with lethal gastrointestinal diseases

Tissue damage caused by oxidative stress is involved in the pathogenesis of several diseases in animals and man, and is believed to play a role in the development of laminitis in horses. The aim of this study was to investigate the oxidative stress associated with laminar lesions in horses with lethal gastrointestinal disorders. Laminar tissue samples of the hoof of 30 horses were used. Tissue samples were divided as follows: six healthy horses (control group-CG), and 24 horses that died after complications of gastrointestinal diseases (group suffering from gastrointestinal disorders-GDG). Superoxide dismutase (SOD2) and nitrotyrosine immunostaining and the severity of laminar lesions were evaluated. Presence of laminar lesions and immunostaining for nitrotyrosine and SOD2 were only evident in horses from the GDG group. Thus, oxidative stress may play a role in the pathogenesis of laminar lesions secondary to gastrointestinal disorders.

Perineuronal nets and schizophrenia: the importance of neuronal coatings

Schizophrenia is a complex brain disorder associated with deficits in synaptic connectivity. The insidious onset of this illness during late adolescence and early adulthood has been reported to be dependent on several key processes of brain development including synaptic refinement, myelination and the physiological maturation of inhibitory neural networks. Interestingly, these events coincide with the appearance of perineuronal nets (PNNs), reticular structures composed of components of the extracellular matrix that coat a variety of cells in the mammalian brain. Until recently, the functions of the PNN had remained enigmatic, but are now considered to be important in development of the central nervous system, neuronal protection and synaptic plasticity, all elements which have been associated with schizophrenia. Here, we review the emerging evidence linking PNNs to schizophrenia. Future studies aimed at further elucidating the functions of PNNs will provide new insights into the pathophysiology of schizophrenia leading to the identification of novel therapeutic targets with the potential to restore normal synaptic integrity in the brain of patients afflicted by this illness.

Cardioprotection against ischaemia/reperfusion by vitamins C and E plus n-3 fatty acids: molecular mechanisms and potential clinical applications

The role of oxidative stress in ischaemic heart disease has been thoroughly investigated in humans. Increased levels of ROS (reactive oxygen species) and RNS (reactive nitrogen species) have been demonstrated during ischaemia and post-ischaemic reperfusion in humans. Depending on their concentrations, these reactive species can act either as benevolent molecules that promote cell survival (at low-to-moderate concentrations) or can induce irreversible cellular damage and death (at high concentrations). Although high ROS levels can induce NF-κB (nuclear factor κB) activation, inflammation, apoptosis or necrosis, low-to-moderate levels can enhance the antioxidant response, via Nrf2 (nuclear factor-erythroid 2-related factor 2) activation. However, a clear definition of these concentration thresholds remains to be established. Although a number of experimental studies have demonstrated that oxidative stress plays a major role in heart ischaemia/reperfusion pathophysiology, controlled clinical trials have failed to prove the efficacy of antioxidants in acute or long-term treatments of ischaemic heart disease. Oral doses of vitamin C are not sufficient to promote ROS scavenging and only down-regulate their production via NADPH oxidase, a biological effect shared by vitamin E to abrogate oxidative stress. However, infusion of vitamin C at doses high enough to achieve plasma levels of 10 mmol/l should prevent superoxide production and the pathophysiological cascade of deleterious heart effects. In turn, n-3 PUFA (polyunsaturated fatty acid) exposure leads to enhanced activity of antioxidant enzymes. In the present review, we present evidence to support the molecular basis for a novel pharmacological strategy using these antioxidant vitamins plus n-3 PUFAs for cardioprotection in clinical settings, such as post-operative atrial fibrillation, percutaneous coronary intervention following acute myocardial infarction and other events that are associated with ischaemia/reperfusion.

Intravenous ascorbic acid infusion improves myocardial perfusion grade during elective percutaneous coronary intervention: relationship with oxidative stress markers

OBJECTIVES

Our goal was to explore whether antioxidant vitamin C infusion is able to affect the microcirculation perfusion in patients undergoing elective percutaneous coronary intervention for stable angina.

BACKGROUND

Periprocedural myocardial injury in the setting of elective percutaneous coronary intervention is associated with increased risk of death, recurrent infarction, and revascularization at follow-up. Despite excellent epicardial blood flow, impaired microcirculatory reperfusion may persist and increases the risk of vascular recurrences. Post-percutaneous coronary intervention induced-oxidative stress is one of the potential mechanisms accounting for impaired perfusion.

METHODS

Fifty-six patients were enrolled in a prospective, single-center, randomized study comparing 1 g vitamin C infusion (16.6 mg/min, over 1 h before percutaneous coronary intervention) versus placebo.

RESULTS

At the baseline, Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade <2 was observed in 89% and in 86% of patients randomized to the placebo or vitamin C infusion group, respectively (p > 0.05). After percutaneous coronary intervention, these percentages decreased in the placebo group (32%) and in greater measure in the vitamin C group (4%, p < 0.01). Complete microcirculatory reperfusion (TIMI myocardial perfusion grade = 3) was achieved in 79% of the vitamin C-treated group compared with 39% of the placebo group (p < 0.01); 8-hydroxy-2-deoxyguanosine (p < 0.002) and 8-iso-prostaglandin F(2alpha) (p < 0.02) plasma levels significantly increased in the placebo group while they were significantly reduced in the vitamin C-treated group (p < 0.0001). TIMI myocardial perfusion grade changes from the baseline showed significant correlation with 8-hydroxy-2-deoxyguanosine (p < 0.006) or 8-iso-prostaglandin F(2alpha) (p < 0.01) plasma levels changes.

CONCLUSIONS

In patients undergoing elective percutaneous coronary intervention, impaired microcirculatory reperfusion is improved by vitamin C infusion suggesting that oxidative stress is implicated in such a phenomenon.

Bioactive eicosanoids: role of prostaglandin F(2α) and F₂-isoprostanes in inflammation and oxidative stress related pathology

Oxidative stress and inflammation are supposed to be the key players of several acute and chronic diseases, and also for progressive aging process. Eicosanoids, especially prostaglandin F(2α) (PGF(2α)) and F₂-isoprostanes are endogenous compounds that are involved both in physiology and the above mentioned pathologies. These compounds are biosynthesized mainly from esterified arachidonic acid through both enzymatic and non-enzymatic free radical-catalysed reactions in vivo, respectively. They have shown to possess potent biological activities in addition to their application as biomarkers of oxidative stress and inflammation. Recent advancement of methodologies has made it possible to quantify these compounds more reliably and apply them in various in vivo studies successfully. Today, experimental and clinical studies have revealed that both PGF(2α) and F₂-isoprostanes are involved in severe acute or chronic inflammatory conditions such as rheumatic diseases, asthma, risk factors of atherosclerosis, diabetes, ischemia-reperfusion, septic shock and many others. These evidences promote that assessment of bioactive PGF(2α) and F₂-isoprostanes simultaneously in body fluids offers unique non-invasive analytical opportunity to study the function of these eicosanoids in physiology, oxidative stress-related and inflammatory diseases, and also in the determination of potency of various radical scavengers, anti-inflammatory compounds, drugs, antioxidants and diet.

PG F(2α) Receptor: A Promising Therapeutic Target for Cardiovascular Disease

Prostaglandins (PGs), a group of key lipid mediators, are involved in numerous physiological and pathological processes including inflammation and cardiovascular homeostasis. Each PG acts on its specific and distinct cell surface G protein-coupled receptors (GPCRs) or peroxisome proliferator-activated receptors (PPARs). Prostaglandin F(2α) receptor (FP) is required for female reproductive function such as luteolysis and parturition. It has recently been implicated in blood pressure regulation, atherosclerosis and other inflammation-related disorders. The emerging role of FP in cardiovascular diseases is highlighted and potential therapeutic translation is discussed in the current review.

Hyperbaric oxygen preconditioning improves myocardial function, reduces length of intensive care stay, and limits complications post coronary artery bypass graft surgery

OBJECTIVE

The objective of this study was to determine whether preconditioning coronary artery disease (CAD) patients with HBO(2) prior to first-time elective on-pump cardiopulmonary bypass (CPB) coronary artery bypass graft surgery (CABG) leads to improved myocardial left ventricular stroke work (LVSW) post CABG. The primary end point of this study was to demonstrate that preconditioning CAD patients with HBO(2) prior to on-pump CPB CABG leads to a statistically significant (P<.05) improvement in myocardial LVSW 24 h post CABG.

METHODS

This randomised control study consisted of 81 (control group=40; HBO(2) group=41) patients who had CABG using CPB. Only the HBO(2) group received HBO(2) preconditioning for two 30-min intervals separated 5 min apart. HBO(2) treatment consisted of 100% oxygen at 2.4 ATA. Pulmonary artery catheters were used to obtain perioperative hemodynamic measurements. All routine perioperative clinical outcomes were recorded. Venous blood was taken pre HBO(2), post HBO(2) (HBO(2) group only), and during the perioperative period for analysis of troponin T.

RESULTS

Prior to CPB, the HBO(2) group had significantly lower pulmonary vascular resistance (P=.03). Post CPB, the HBO(2) group had increased stroke volume (P=.01) and LVSW (P=.005). Following CABG, there was a smaller rise in troponin T in HBO(2) group suggesting that HBO(2) preconditioning prior to CABG leads to less postoperative myocardial injury. Post CABG, patients in the HBO(2) group had an 18% (P=.05) reduction in length of stay in the intensive care unit (ICU). Intraoperatively, the HBO(2) group had a 57% reduction in intraoperative blood loss (P=.02). Postoperatively, the HBO(2) group had a reduction in blood loss (11.6%), blood transfusion (34%), low cardiac output syndrome (10.4%), inotrope use (8%), atrial fibrillation (11%), pulmonary complications (12.7%), and wound infections (7.6%). Patients in the HBO(2) group saved US$116.49 per ICU hour.

CONCLUSION

This study met its primary end point and demonstrated that preconditioning CAD patients with HBO(2) prior to on-pump CPB CABG was capable of improving LVSW. Additionally, this study also showed that HBO(2) preconditioning prior to CABG reduced myocardial injury, intraoperative blood loss, ICU length of stay, postoperative complications, and saved on cost, post CABG.

F2-isoprostane induced prostaglandin formation in the rabbit

F(2)-isoprostanes, non-enzymatic free radical mediated products of arachidonic acid, have shown to form during various oxidant stress status and have potent biological effects. This study investigates to what extent 8-iso-PGF(2alpha) (a major F(2)-isoprostane), a bioactive product of lipid peroxidation can modify endogenous prostaglandin F(2alpha) (PGF(2alpha)) formation since prostaglandins are inflammatory as well as potent vasoregulatory substances that modulate diverse important physiological functions, and also form during acute and chronic inflammation. An immediate appearance and disappearance of 8-iso-PGF(2alpha) was seen in both plasma and urine within a short interval after i.v. administration of 43 microg/kg of 8-iso-PGF(2alpha) to the rabbits. A successive but differential formation of PGF(2alpha) resulted in a rapid and pulsatile increase of plasma 15-keto-dihydro-PGF(2alpha), a major metabolite of primary PGF(2alpha). Later, this compound was excreted efficiently as intact compound into the urine during the 3 h of experiment. A 8-fold increase of PGF(2alpha) metabolite in plasma at 10 min and 12-fold increase in the urine at 30-60 after the i.v. administration of 8-iso-PGF(2alpha) was observed which continued throughout the 3 h of experiment. This observation suggests that pharmacologically administered or endogenously produced 8-iso-PGF(2alpha) during oxidant stress induces prostaglandin formation presumably through the classical cyclooxygenase-catalysed arachidonic acid oxidation which might be inflammatory itself to the cells and exerts further vasoconstrictive effects.

Antioxidant enzyme gene transfer for ischemic diseases

The balance of redox is pivotal for normal function and integrity of tissues. Ischemic insults occur as results of a variety of conditions, leading to an accumulation of reactive oxygen species (ROS) and an imbalanced redox status in the tissues. The oxidant stress may activate signaling mechanisms provoking more toxic events, and eventually cause tissue damage. Therefore, treatments with antioxidants, free radical scavengers and their mimetics, as well as gene transfer approaches to overexpress antioxidant genes represent potential therapeutic options to correct the redox imbalance. Among them, antioxidant gene transfer may enhance the production of antioxidant scavengers, and has been employed to experimentally prevent or treat ischemic injury in cardiovascular, pulmonary, hepatic, intestinal, central nervous or other systems in animal models. With improvements in vector systems and delivery approaches, innovative antioxidant gene therapy has conferred better outcomes for myocardial infarction, reduced restenosis after coronary angioplasty, improved the quality and function of liver grafts, as well as outcome of intestinal and cerebral ischemic attacks. However, it is crucial to be mindful that like other therapeutic armentarium, the efficacy of antioxidant gene transfer requires extensive preclinical investigation before it can be used in patients, and that it may have unanticipated short- or long-term adverse effects. Thus, it is critical to balance between the therapeutic benefits and potential risks, to develop disease-specific antioxidant gene transfer strategies, to deliver the therapy with an optimal time window and in a safe manner. This review attempts to provide the rationale, the most effective approaches and the potential hurdles of available antioxidant gene transfer approaches for ischemic injury in various organs, as well as the possible directions of future preclinical and clinical investigations of this highly promising therapeutic modality.

Plasma N-epsilon-(carboxymethyl)lysine levels are associated with the extent of vessel injury after coronary arterial stenting

OBJECTIVE

In animal models, increased tissue receptor for advanced glycation end products and its ligands, including N-epsilon-(carboxymethyl)lysine (CML), are critically implicated in postprocedural intimal hyperplasia after balloon injury. In patients undergoing percutaneous coronary interventions with stenting, we investigated whether plasma levels of CML and the soluble form of receptor for advanced glycation end products (sRAGE) changed during poststenting follow-up.

METHODS

We studied 81 patients with coronary artery disease who underwent successful percutaneous coronary interventions. Plasma levels of CML and sRAGE were measured before intervention, and at 1 day and 180 days of follow-up.

RESULTS

CML levels increased significantly at day 1 after stenting and persisted at an elevated level at 180 days (P=0.013), whereas sRAGE levels increased significantly at 180 days (P=0.011). CML levels were significantly higher in multivessel-treated patients than in single-vessel-treated patients both at 1 day and 180 days of follow-up. In addition, CML values were positively associated with the extent of stent area at 1 day and 180 days of follow-up (r=0.278, P=0.022 and r=0.315, P=0.012, respectively). In logistic regression analysis, only the extent of stent area predicted adverse clinical events at 180-day follow-up (P=0.03, odds ratio=14.25, confidence interval=1.25-162.2).

CONCLUSION

This study supports the hypothesis that increased circulating levels of CML occurred in the presence of vascular injury. This persistent rise of CML could amplify an inflammatory phenomenon triggered by stent placement and thus contributes to coronary artery disease progression.

F2-isoprostanes in human health and diseases: from molecular mechanisms to clinical implications

Oxidative stress is implicated as one of the major underlying mechanisms behind many acute and chronic diseases, and involved in normal aging. However, the measurement of free radicals or their end products is complicated. Thus, proof of association of free radicals in pathologic conditions has been absent. Isoprostanes are prostaglandin-like bioactive compounds that are biosynthesized in vivo independent of cyclooxygenases, principally through free-radical catalyzation of arachidonic acid. Isoprostanes are now considered to be reliable biomarkers of oxidative stress, as evidenced by an autonomous study organized recently by the National Institutes of Health (NIH) in the United States. A number of these compounds have potent biologic activities such as vasoconstrictive and certain inflammatory properties. Isoprostanes are involved in many human diseases. Additionally, elevated levels of F(2)-isoprostanes have been seen in normal human pregnancy and after intake of some fatty acids, but their physiologic assignments have not yet been distinctive. This evidence indicates that measurement of bioactive F(2)-isoprostanes in body fluids offers a unique noninvasive analytic utensil to study the role of free radicals in physiology, oxidative stress-related diseases, experimental acute or chronic inflammatory conditions, and also in the assessment of various antioxidants, radical scavengers, and drugs.

Role of extracellular superoxide in neutrophil activation: interactions between xanthine oxidase and TLR4 induce proinflammatory cytokine production

Reactive oxygen species (ROS) contribute to neutrophil activation and the development of acute inflammatory processes in which neutrophils play a central role. However, there is only limited information concerning the mechanisms through which extracellular ROS, and particularly cell membrane-impermeable species, such as superoxide, enhance the proinflammatory properties of neutrophils. To address this issue, neutrophils were exposed to superoxide generating combinations of xanthine oxidase and hypoxanthine or lumazine. Extracellular superoxide generation induced nuclear translocation of nuclear factor-κB (NF-κB) and increased neutrophil production of the NF-κB-dependent cytokines tumor necrosis factor-α (TNF-α) and macrophage inhibitory protein-2 (MIP-2). In contrast, there were no changes in TNF-α or MIP-2 expression when neutrophils lacking Toll-like receptor-4 (TLR4) were exposed to extracellular superoxide. Immunoprecipitation, confocal microscopy, and fluorescence resonance energy transfer (FRET) studies demonstrated association between TLR4 and xanthine oxidase. Exposure of neutrophils to heparin attenuated binding of xanthine oxidase to the cell surface as well as interactions with TLR4. Heparin also decreased xanthine oxidase-induced nuclear translocation of NF-κB as well as production of proinflammatory cytokines. These results demonstrate that extracellular superoxide has proinflammatory effects on neutrophils, predominantly acting through an TLR4-dependent mechanism that enhances nuclear translocation of NF-κB and increases expression of NF-κB-dependent cytokines.

Novel cyclooxygenase-catalyzed bioactive prostaglandin F2alpha from physiology to new principles in inflammation

Prostaglandin F2alpha (PGF2alpha), a foremost stable vasoactive cyclooxygenase (COX)-catalyzed prostaglandin, regulates a number of key physiological functions such as luteolysis, ovarian function, luteal maintenance of pregnancy, and parturition as a constitutive part of ongoing reproductive processes of the body. It has recently been implicated in the regulation of intricate pathophysiological processes, such as acute and chronic inflammation, cardiovascular and rheumatic diseases. Since the discovery of a second isoform of COXs, it has been shown that PGF2alpha can be formed in vivo from arachidonic acid through both isoforms of COXs, namely cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Being synthesized in various parts of the body, it metabolizes instantly to a number of rather inactive metabolites mainly in the lungs, liver, kidney, and efficiently excretes into the urine. 15-Keto-dihydro-PGF2alpha, a major stable metabolite of PGF2alpha that reflects in vivo PGF2alpha biosynthesis, is found in larger quantities than its parent compound in the circulation and urine in basal physiological conditions, with short-lived pulses during luteolysis, induced termination of pregnancy and parturition, and is increased in tissues and various body fluids during acute, sub-chronic, and severe chronic inflammation. Further, the close relationship of PGF2alpha with a number of risk factors for atherosclerosis indicates its major role in inflammation pathology. This review addresses multiple aspects of PGF2alpha in addition to its emerging role in physiology to inflammation.

Oxidative stress during coronary artery bypass operations: importance of surgical trauma and drug treatment

OBJECTIVE

To investigate oxidative stress and myocardial injury at different stages of coronary artery bypass grafting (CABG).

DESIGN

Twenty patients underwent CABG with use of cardiopulmonary bypass (CPB) and with intermittent sampling of plasma and urine. Main markers were: 8-iso-PGF2alpha (oxidative stress); troponin T (myocardial injury); and 15-keto-dihydro-PGF2alpha and hsCRP (inflammation).

RESULTS

Plasma 8-iso-PGF2alpha increased after start of surgery, but there was no further rise during CPB or after aortic cross-clamp release and no significant myocardial arterio-venous differences. An increase in troponin T was seen early after the operation, but no relationship was established between 8-iso-PGF2alpha and troponin T. 8-iso-PGF2alpha levels were elevated by preoperative withdrawal of acetylsalicylic acid (ASA) but reduced by intraoperative use of heparin. 15-keto-dihydro-PGF2alpha was elevated during operation and hsCRP following operation.

CONCLUSIONS

In the present study oxidative stress was multifactorial in origin with main impacts from surgical trauma, less from CPB and little if any from myocardial ischemia-reperfusion events. In addition, cardiovascular drugs in common use like ASA and heparin seemed to influence the pro- and antioxidant balance, a finding that has to be confirmed in future studies.

Exposure to hydrogen peroxide diminishes NF-kappaB activation, IkappaB-alpha degradation, and proteasome activity in neutrophils

Although ROS can participate in modulating the activity of the transcriptional factor NF-kappaB and expression of NF-kappaB-dependent genes, the mechanisms involved and the roles of specific ROS have not been fully determined. In particular, individual ROS appear to have differing effects on NF-kappaB activation dependent on the cell population studied. In the present study, we examined the ability of H(2)O(2) to affect NF-kappaB activation in LPS-stimulated murine neutrophils and macrophages. Exposure of bone marrow or peritoneal neutrophils to H(2)O(2) was associated with reduced nuclear translocation of NF-kappaB and decreased production of the NF-kappaB-dependent cytokines TNF-alpha and macrophage inhibitory protein-2. H(2)O(2) treatment resulted in diminished trypsin- and chymotrypsin-like proteasome activity. The degradation of IkappaB-alpha normally found in LPS-treated neutrophils was prevented when H(2)O(2) was added to cell cultures. In contrast to the effects found in neutrophils, H(2)O(2) did not affect chymotrypsin-like proteasomal activity or cytokine production in LPS-stimulated macrophages, even though trypsin-like proteasomal activity was reduced. These results demonstrate that the effects of H(2)O(2) on NF-kappaB and proteasomal activity are cell population specific.

Atrial Fibrillation and Plasma Troponin I Elevation After Cardiac Surgery: Relation to Inflammation-Associated Parameters

BACKGROUND

Recent studies have demonstrated correlation between inflammation to plasma troponin (cTnI) levels elevation and atrial fibrillation (AF) in noncardiac surgery settings. The goal of this prospective study was to examine the relation between inflammation associated parameters (IAPs) to post cardiac surgery cTnI elevation and AF.

METHODS

A single post CABG cTnI measurement was assessed in 156 consecutive patients. Clinical, operative and postoperative data, IAPs (hypophosphatemia, preoperative statin treatment, immediate postoperative fever, and prolonged mechanical ventilation) and in-hospital AF episodes were prospectively recorded.

RESULTS

Mean cTnI level was 14.4 +/- 12.4 ng/mL. In the two in-hospital deaths (1.2%) cTnI concentration was less than 12 ng/mL. Cardiac troponin-I levels were significantly higher in patients not preoperatively treated with statins (21.6 +/- 4.1 vs. 13.3 +/- 0.9, p = 0.05), in patients who needed intraoperative cardioversion (16.7 +/- 2.2 vs. 12.2 +/- 0.9, p = 0.07), in patients with postoperative hypophosphatemia (16.9 +/- 10.0 vs. 11.1 +/- 13.7, p = 0.04), postoperative fever (18.6 +/- 3.0 vs. 13.7 +/- 1.0, p = 0.07) and postoperative respiratory complications (23.9 +/- 4.3 vs. 13.5 +/- 1.0, p = 0.04). Step-wise logistic regression analysis revealed the following parameters as independently associated with elevated cTnI levels: preoperative statin treatment (CI 95%-15.9; -1.7, p = 0.02), intraoperative ventricular arrhythmia (CI 95%-0.7; 13.8, p = 0.08), hypophosphatemia (CI 95% 0.9; 8.6, p = 0.02), postoperative fever (CI 95% 0.9; 11.0, p = 0.02), and postoperative respiratory complications (CI 95% 0.1; 0.5, p = 0.01). Of the 156 patients, 50 (32.1%) had postoperative AF. The first episode of AF occurred between postoperative day 1 and 6 (mean-day 2). Mean duration of AF was 21.8 +/- 8.1 hours. Postoperative AF was significantly associated with age above 75 (50% vs. 29.4%, p = 0.01), hypertension (37% vs. 18%, p = 0.02), preoperative calcium channel blockers treatment (44% vs. 26%, p = 0.02), furosemide treatment (58% vs. 30%, p = 0.05), and preoperative left atrial diameter above 40 mm (56% vs. 29%, p = 0.01). Postoperatively, AF was significantly associated with postoperative renal failure (70% vs. 29%, p = 0.01), respiratory complications (61% vs. 29%, p = 0.02), and prolonged hospital stay (OR 1.1; CI 1.0-1.3; p < 0.05). No association was found between troponin levels and postoperative AF. Multivariable analysis found only left atrial enlargement and prolonged hospital stay independently associated with AF.

CONCLUSIONS

A significant correlation between clinical IAPs and cTnI plasma level elevation was found after cardiac surgery. There was no correlation between these parameters and postoperative AF, and there was no correlation between postoperative plasma cTnI levels and the occurrence of AF. Preoperative treatment with statins may be beneficial in reducing postoperative inflammatory response but further study has to be carried out.

Percutaneous coronary intervention increases leptin and decreases adiponectin levels

OBJECTIVE

The study was designed to examine the effect of percutaneous coronary intervention (PCI) on adiponectin and leptin levels. We have previously demonstrated that PCI triggers a systemic inflammatory response. We hypothesized that inflammation participates in the pathogenesis of diabetes mellitus and the metabolic syndrome by modulating levels of adiponectin and leptin.

DESIGN

Prospective study in which inflammation was induced by PCI.

PATIENTS

Forty-eight patients with stable coronary artery disease and without diabetes mellitus.

MEASUREMENTS

High-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), leptin and adiponectin were measured at baseline and 48 h after the procedure.

RESULTS

Following PCI, hs-CRP increased by 211%, IL-6 by 87% and leptin by 19%, while adiponectin decreased by 14% (P < 0.001 for all). The change in IL-6 correlated with that in hs-CRP (rho = 0.32; P = 0.027), as did the changes in IL-6 and leptin (rho = 0.31; P = 0.03). The change in adiponectin, however, did not correlate with the change in any of the other markers.

CONCLUSION

This study demonstrates that PCI affects the levels of adiponectin and leptin within 48 h. These effects may be secondary to the inflammatory response triggered by PCI.

Participation of superoxide in neutrophil activation and cytokine production

Reactive oxygen species (ROS) can participate in cellular signaling and have been shown to modulate activation of the transcriptional regulatory factor NF-kappaB. However, the effects of ROS can differ in various cell populations. To examine the role of superoxide in neutrophil activation, we exposed resting neutrophils and neutrophils stimulated with LPS to paraquat, an agent that specifically increases intracellular superoxide concentrations. Culture of resting neutrophils with paraquat resulted in increased production of the proinflammatory cytokines TNF-alpha and MIP-2, enhanced degradation of IkappaB-alpha, and increased nuclear accumulation of NF-kappaB. Such effects of paraquat were due to intracellular superoxide (O2-) since they were blocked by the non-specific antioxidant N-acetyl cysteine and the cell permeable superoxide scavenger Tiron, but not by catalase, which facilitates the conversion of H2O2 to H2O and O2. Similar potentiating effects of paraquat were found in LPS-stimulated neutrophils. Exposure of neutrophils to paraquat also enhanced phosphorylation of Ser536 in the p65 subunit of NF-kappaB an event associated with increased transcriptional activity. Examination of kinases critical for LPS-stimulated gene expression showed that addition of paraquat to resting or LPS exposed neutrophils enhanced activation of p38 MAPK, but not that of Akt or ERK1/2. The potentiation of NF-kappaB translocation and proinflammatory cytokine production, but not of Ser536 p65 phosphorylation, by paraquat was dependent on activation of p38 MAPK. These results demonstrate that increased intracellular superoxide concentrations are proinflammatory in neutrophils, acting through a p38 MAPK dependent mechanism that results in enhanced nuclear accumulation of NF-kappaB and increased expression of NF-kappaB dependent proinflammatory cytokines.

Factors regulating isoprostane formation in vivo

Discovery of the F2-isoprostanes, a group of prostaglandin F2-like compounds biosynthesized from arachidonic acid nonenzymatically, has uncovered a new and novel facet of free radical biology. Some of these compounds are bioactive and thus may mediate adverse effects associated with oxidant stress. F2-Isoprostanes have also been shown to be reliable biomarkers of lipid peroxidation. Factors influencing their formation and metabolism have been studied to some extent, although much remains to be determined. The purpose of this review is to summarize our current knowledge of conditions that modulate endogenous generation of these compounds. Isoprostanes have a wide daily variation in secretion in humans. Although normal levels can be defined, these compounds are found in increased concentrations in various pathophysiological states, including ischemia-reperfusion injury, atherosclerosis, and diabetes, and in experimental conditions of oxidative stress and inflammation. Alterations in isoprostane biosynthesis, secretion, and excretion in normal physiology and in pathophysiological states are due to the various types of endogenous and exogenous regulatory mechanisms that control the availability of precursors required for isoprostane synthesis, such as dietary and tissue arachidonic acid content, oxygen concentration, and the generation of various free radical species. Selected aspects of issues related to isoprostane formation and metabolism in vivo will be examined herein.