Antioxidant vitamins reduce oxidative stress and ventricular remodeling in patients with acute myocardial infarction

Potential Role of Natural Antioxidants in Countering Reperfusion Injury in Acute Myocardial Infarction and Ischemic Stroke

Stroke and acute myocardial infarction are leading causes of mortality worldwide. The latter accounts for approximately 9 million deaths annually. In turn, ischemic stroke is a significant contributor to adult physical disability globally. While reperfusion is crucial for tissue recovery, it can paradoxically exacerbate damage through oxidative stress (OS), inflammation, and cell death. Therefore, it is imperative to explore diverse approaches aimed at minimizing ischemia/reperfusion injury to enhance clinical outcomes. OS primarily arises from an excessive generation of reactive oxygen species (ROS) and/or decreased endogenous antioxidant potential. Natural antioxidant compounds can counteract the injury mechanisms linked to ROS. While promising preclinical results, based on monotherapies, account for protective effects against tissue injury by ROS, translating these models into human applications has yielded controversial evidence. However, since the wide spectrum of antioxidants having diverse chemical characteristics offers varied biological actions on cell signaling pathways, multitherapy has emerged as a valuable therapeutic resource. Moreover, the combination of antioxidants in multitherapy holds significant potential for synergistic effects. This study was designed with the aim of providing an updated overview of natural antioxidants suitable for preventing myocardial and cerebral ischemia/reperfusion injuries.

Targeting ferroptosis: a novel insight against myocardial infarction and ischemia-reperfusion injuries

Ferroptosis, a newly discovered form of regulated cell death dependent on iron and reactive oxygen species, is mainly characterized by mitochondrial shrinkage, increased density of bilayer membranes and the accumulation of lipid peroxidation, causing membrane lipid peroxidation and eventually cell death. Similar with the most forms of regulated cell death, ferroptosis also participated in the pathological metabolism of myocardial infarction and myocardial ischemia/reperfusion injuries, which are still the leading causes of death worldwide. Given the crucial roles ferroptosis played in cardiovascular diseases, such as myocardial infarction and myocardial ischemia/reperfusion injuries, it is considerable to delve into the molecular mechanisms of ferroptosis contributing to the progress of cardiovascular diseases, which might offer the potential role of ferroptosis as a targeted treatment for a wide range of cardiovascular diseases. This review systematically summarizes the process and regulatory metabolisms of ferroptosis, discusses the relationship between ferroptosis and myocardial infarction as well as myocardial ischemia/reperfusion injuries, which might potentially provide novel insights for the pathological metabolism and original ideas for the prevention as well as treatment targeting ferroptosis of cardiovascular diseases such as myocardial infarction and myocardial ischemia/reperfusion injuries.

Eugenol attenuates ischemia-mediated oxidative stress in cardiomyocytes via acetylation of histone at H3K27

Despite clinical advances, ischemia-induced cardiac diseases remain an underlying cause of death worldwide. Epigenetic modifications, especially alterations in the acetylation of histone proteins play a pivotal role in counteracting stressful conditions, including ischemia. In our study, we found that histone active mark H3K27ac was significantly reduced and histone repressive mark H3K27me3 was significantly upregulated in the cardiomyocytes exposed to the ischemic condition. Then, we performed a high throughput drug screening assay using rat ventricular cardiomyocytes during the ischemic condition and screened an antioxidant compound library comprising of 84 drugs for H3K27ac by fluorescence microscopy. Our data revealed that most of the phenolic compounds like eugenol, apigenin, resveratrol, bis-demethoxy curcumin, D-gamma-tocopherol, ambroxol, and non-phenolic compounds like l-Ergothioneine, ciclopirox ethanolamine, and Tanshinone IIA have a crucial role in maintaining the cellular H3K27ac histone marks during the ischemic condition. Further, we tested the role of eugenol on cellular protection during ischemia. Our study shows that ischemia significantly reduces cellular viability and increases total reactive oxygen species (ROS), and mitochondrial ROS in the cells. Interestingly, eugenol treatment significantly restores the cellular acetylation at H3K27, decreases cellular ROS, and improves cellular viability. To explore the mechanism of eugenol-medicated inhibition of deacetylation, we performed a RNAseq experiment. Analysis of transcriptome data using IPA indicated that eugenol regulates several cellular functions associated with cardiovascular diseases, and metabolic processes. Further, we found that eugenol regulates the expression of HMGN1, CD151 and Ppp2ca genes during ischemia. Furthermore, we found that eugenol might protect the cells from ischemia through modulation of HMGN1 protein expression, which plays an active role in regulation of histone acetylation and cellular protection during stress. Thus, our study indicated that eugenol can be exploited as an agent to protect the ischemic cells and also could be used to develop a novel drug for treating cardiac disease.

Anti-ischemic effect of Tamarindus indica L. seed extract against myocardial hypoxic injury

Background: Ischemic heart disease is a leading cause of death in patients with cardiovascular disease. Natural products containing high antioxidant activity have been used as an alternative therapy to improve the living conditions of patients. In this study, we examine the protective effect of tamarind seed (TS) on myocardial hypoxic injury. Methods: The hypoxia model was mimicked by mineral oil overlayed on H9c2 cardiomyoblasts for 4 h. TS extract was pretreated and administered during the hypoxic condition. Radical scavenging activity of TS extract was measured and exhibited very potent antioxidant activities on 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. Results: TS extract at a concentration of 10 µg/ml significantly reversed the effect of hypoxia-induced cell death and intracellular reactive oxygen species (ROS) production. We also observed hypoxia-induced over-expression of both inflammatory cytokine mRNA and activation of cellular apoptosis. Pretreatment of TS extract significantly reduced hypoxia-induced HIF-1a and pro-inflammatory cytokine production, IL-1b and IL-6. The Western blot analysis for apoptotic regulatory molecules, caspase 3, caspase 8 and Bax proteins, also showed hypoxia injury reversal by TS extract treatment. Conclusions: The results suggest that the anti-ischemic effect of TS extract protects against hypoxia-induced injury and has potential to be an effective alternative therapy for ischemic heart disease and oxidative-damage related disease.

The underlying pathological mechanism of ferroptosis in the development of cardiovascular disease

Cardiovascular diseases (CVDs) have been attracting the attention of academic society for decades. Numerous researchers contributed to figuring out the core mechanisms underlying CVDs. Among those, pathological decompensated cellular loss posed by cell death in different kinds, namely necrosis, apoptosis and necroptosis, was widely regarded to accelerate the pathological development of most heart diseases and deteriorate cardiac function. Recently, apart from programmed cell death revealed previously, ferroptosis, a brand-new cellular death identified by its ferrous-iron-dependent manner, has been demonstrated to govern the occurrence and development of different cardiovascular disorders in many types of research as well. Therefore, clarifying the regulatory function of ferroptosis is conducive to finding out strategies for cardio-protection in different conditions and improving the prognosis of CVDs. Here, molecular mechanisms concerned are summarized systematically and categorized to depict the regulatory network of ferroptosis and point out potential therapeutic targets for diverse cardiovascular disorders.

Antioxidant Cardioprotection against Reperfusion Injury: Potential Therapeutic Roles of Resveratrol and Quercetin

Ischemia-reperfusion myocardial damage is a paradoxical tissue injury occurring during percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI) patients. Although this damage could account for up to 50% of the final infarct size, there has been no available pharmacological treatment until now. Oxidative stress contributes to the underlying production mechanism, exerting the most marked injury during the early onset of reperfusion. So far, antioxidants have been shown to protect the AMI patients undergoing PCI to mitigate these detrimental effects; however, no clinical trials to date have shown any significant infarct size reduction. Therefore, it is worthwhile to consider multitarget antioxidant therapies targeting multifactorial AMI. Indeed, this clinical setting involves injurious effects derived from oxygen deprivation, intracellular pH changes and increased concentration of cytosolic Ca²⁺ and reactive oxygen species, among others. Thus, we will review a brief overview of the pathological cascades involved in ischemia-reperfusion injury and the potential therapeutic effects based on preclinical studies involving a combination of antioxidants, with particular reference to resveratrol and quercetin, which could contribute to cardioprotection against ischemia-reperfusion injury in myocardial tissue. We will also highlight the upcoming perspectives of these antioxidants for designing future studies.

Ion Channel Impairment and Myofilament Ca2+ Sensitization: Two Parallel Mechanisms Underlying Arrhythmogenesis in Hypertrophic Cardiomyopathy

Life-threatening ventricular arrhythmias are the main clinical burden in patients with hypertrophic cardiomyopathy (HCM), and frequently occur in young patients with mild structural disease. While massive hypertrophy, fibrosis and microvascular ischemia are the main mechanisms underlying sustained reentry-based ventricular arrhythmias in advanced HCM, cardiomyocyte-based functional arrhythmogenic mechanisms are likely prevalent at earlier stages of the disease. In this review, we will describe studies conducted in human surgical samples from HCM patients, transgenic animal models and human cultured cell lines derived from induced pluripotent stem cells. Current pieces of evidence concur to attribute the increased risk of ventricular arrhythmias in early HCM to different cellular mechanisms. The increase of late sodium current and L-type calcium current is an early observation in HCM, which follows post-translation channel modifications and increases the occurrence of early and delayed afterdepolarizations. Increased myofilament Ca²⁺ sensitivity, commonly observed in HCM, may promote afterdepolarizations and reentry arrhythmias with direct mechanisms. Decrease of K⁺-currents due to transcriptional regulation occurs in the advanced disease and contributes to reducing the repolarization-reserve and increasing the early afterdepolarizations (EADs). The presented evidence supports the idea that patients with early-stage HCM should be considered and managed as subjects with an acquired channelopathy rather than with a structural cardiac disease.

Joint Cardioprotective Effect of Vitamin C and Other Antioxidants against Reperfusion Injury in Patients with Acute Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Percutaneous coronary intervention (PCI) has long remained the gold standard therapy to restore coronary blood flow after acute myocardial infarction (AMI). However, this procedure leads to the development of increased production of reactive oxygen species (ROS) that can exacerbate the damage caused by AMI, particularly during the reperfusion phase. Numerous attempts based on antioxidant treatments, aimed to reduce the oxidative injury of cardiac tissue, have failed in achieving an effective therapy for these patients. Among these studies, results derived from the use of vitamin C (Vit C) have been inconclusive so far, likely due to suboptimal study designs, misinterpretations, and the erroneous conclusions of clinical trials. Nevertheless, recent clinical trials have shown that the intravenous infusion of Vit C prior to PCI-reduced cardiac injury biomarkers, as well as inflammatory biomarkers and ROS production. In addition, improvements of functional parameters, such as left ventricular ejection fraction (LVEF) and telediastolic left ventricular volume, showed a trend but had an inconclusive association with Vit C. Therefore, it seems reasonable that these beneficial effects could be further enhanced by the association with other antioxidant agents. Indeed, the complexity and the multifactorial nature of the mechanism of injury occurring in AMI demands multitarget agents to reach an enhancement of the expected cardioprotection, a paradigm needing to be demonstrated. The present review provides data supporting the view that an intravenous infusion containing combined safe antioxidants could be a suitable strategy to reduce cardiac injury, thus improving the clinical outcome, life quality, and life expectancy of patients subjected to PCI following AMI.

Targeting Ferroptosis against Ischemia/Reperfusion Cardiac Injury

Ischemic heart disease is a leading cause of death worldwide. Primarily, ischemia causes decreased oxygen supply, resulting in damage of the cardiac tissue. Naturally, reoxygenation has been recognized as the treatment of choice to recover blood flow through primary percutaneous coronary intervention. This treatment is the gold standard therapy to restore blood flow, but paradoxically it can also induce tissue injury. A number of different studies in animal models of acute myocardial infarction (AMI) suggest that ischemia-reperfusion injury (IRI) accounts for up to 50% of the final myocardial infarct size. Oxidative stress plays a critical role in the pathological process. Iron is an essential mineral required for a variety of vital biological functions but also has potentially toxic effects. A detrimental process induced by free iron is ferroptosis, a non-apoptotic type of programmed cell death. Accordingly, efforts to prevent ferroptosis in pathological settings have focused on the use of radical trapping antioxidants (RTAs), such as liproxstatin-1 (Lip-1). Hence, it is necessary to develop novel strategies to prevent cardiac IRI, thus improving the clinical outcome in patients with ischemic heart disease. The present review analyses the role of ferroptosis inhibition to prevent heart IRI, with special reference to Lip-1 as a promising drug in this clinicopathological context.

Protecting the aging eye with hydrogen sulfide

Research demonstrates that senescence is associated with tissue and organ dysfunction, and the eye is no exception. Sequelae arising from aging have been well defined as distinct clinical entities and vision impairment has significant psychosocial consequences. Retina and adjacent tissues like retinal pigmented epithelium and choroid are the key structures that are required for visual perception. Any structural and functional changes in retinal layers and blood retinal barrier could lead to age-related macular degeneration, diabetic retinopathy, and glaucoma. Further, there are significant oxygen gradients in the eye that can lead to excessive reactive oxygen species, resulting in endoplasmic reticulum and mitochondrial stress response. These radicals are source of functional and morphological impairment in retinal pigmented epithelium and retinal ganglion cells. Therefore, ocular diseases could be summarized as disturbance in the redox homeostasis. Hyperhomocysteinemia is a risk factor and causes vascular occlusive disease of the retina. Interestingly, hydrogen sulfide (H2S) has been proven to be an effective antioxidant agent, and it can help treat diseases by alleviating stress and inflammation. Concurrent glutamate excitotoxicity, endoplasmic reticulum stress, and microglia activation are also linked to stress; thus, H2S may offer additional interventional strategy. A refined understanding of the aging eye along with H2S biology and pharmacology may help guide newer therapies for the eye.

Vitamin C for Cardiac Protection during Percutaneous Coronary Intervention: A Systematic Review of Randomized Controlled Trials

Percutaneous coronary intervention (PCI) is the preferred treatment for acute coronary syndrome (ACS) secondary to atherosclerotic coronary artery disease. This nonsurgical procedure is also used for selective patients with stable angina. Although the procedure is essential for restoring blood flow, reperfusion can increase oxidative stress as a side effect. We address whether intravenous infusion of vitamin C (VC) prior to PCI provides a benefit for cardioprotection. A total of eight randomized controlled trials (RCT) reported in the literature were selected from 371 publications through systematic literature searches in six electronic databases. The data of VC effect on cardiac injury biomarkers and cardiac function were extracted from these trials adding up to a total of 1185 patients. VC administration reduced cardiac injury as measured by troponin and CK-MB elevations, along with increased antioxidant reservoir, reduced reactive oxygen species (ROS) and decreased inflammatory markers. Improvement of the left ventricular ejection fraction (LVEF) and telediastolic left ventricular volume (TLVV) showed a trend but inconclusive association with VC. Intravenous infusion of VC before PCI may serve as an effective method for cardioprotection against reperfusion injury.

Restoration of skeletal muscle homeostasis by hydrogen sulfide during hyperhomocysteinemia-mediated oxidative/ER stress condition 1

Elevated homocysteine (Hcy), i.e., hyperhomocysteinemia (HHcy), causes skeletal muscle myopathy. Among many cellular and metabolic alterations caused by HHcy, oxidative and endoplasmic reticulum (ER) stress are considered the major ones; however, the precise molecular mechanism(s) in this process is unclear. Nevertheless, there is no treatment option available to treat HHcy-mediated muscle injury. Hydrogen sulfide (H₂S) is increasingly recognized as a potent anti-oxidant, anti-apoptotic/necrotic/pyroptotic, and anti-inflammatory compound and also has been shown to improve angiogenesis during ischemic injury. Patients with CBS mutation produce less H₂S, making them vulnerable to Hcy-mediated cellular damage. Many studies have reported bidirectional regulation of ER stress in apoptosis through JNK activation and concomitant attenuation of cell proliferation and protein synthesis via PI3K/AKT axis. Whether H₂S mitigates these detrimental effects of HHcy on muscle remains unexplored. In this review, we discuss molecular mechanisms of HHcy-mediated oxidative/ER stress responses, apoptosis, angiogenesis, and atrophic changes in skeletal muscle and how H₂S can restore skeletal muscle homeostasis during HHcy condition. This review also highlights the molecular mechanisms on how H₂S could be developed as a clinically relevant therapeutic option for chronic conditions that are aggravated by HHcy.

Remote ischemic conditioning as a cytoprotective strategy in vasculopathies during hyperhomocysteinemia: An emerging research perspective

Higher levels of nonprotein amino acid homocysteine (Hcy), that is, hyperhomocysteinemia (HHcy) (~5% of general population) has been associated with severe vasculopathies in different organs; however, precise molecular mechanism(s) as to how HHcy plays havoc with body's vascular networks are largely unknown. Interventional modalities have not proven beneficial to counter multifactorial HHcy's effects on the vascular system. An ancient Indian form of exercise called 'yoga' causes transient ischemia as a result of various body postures however the cellular mechanisms are not clear. We discuss a novel perspective wherein we argue that application of remote ischemic conditioning (RIC) could, in fact, deliver anticipated results to patients who are suffering from chronic vascular dysfunction due to HHcy. RIC is the mechanistic phenomenon whereby brief episodes of ischemia-reperfusion events are applied to distant tissues/organs; that could potentially offer a powerful tool in mitigating chronic lethal ischemia in target organs during HHcy condition via simultaneous reduction of inflammation, oxidative and endoplasmic reticulum stress, extracellular matrix remodeling, fibrosis, and angiogenesis. We opine that during ischemic conditioning our organs cross talk by releasing cellular messengers in the form of exosomes containing messenger RNAs, circular RNAs, anti-pyroptotic factors, protective cytokines like musclin, transcription factors, small molecules, anti-inflammatory, antiapoptotic factors, antioxidants, and vasoactive gases. All these could help mobilize the bone marrow-derived stem cells (having tissue healing properties) to target organs. In that context, we argue that RIC could certainly play a savior's role in an unfortunate ischemic or adverse event in people who have higher levels of the circulating Hcy in their systems.

Reactive Oxygen Species, Endoplasmic Reticulum Stress and Mitochondrial Dysfunction: The Link with Cardiac Arrhythmogenesis

BACKGROUND

Cardiac arrhythmias represent a significant problem globally, leading to cerebrovascular accidents, myocardial infarction, and sudden cardiac death. There is increasing evidence to suggest that increased oxidative stress from reactive oxygen species (ROS), which is elevated in conditions such as diabetes and hypertension, can lead to arrhythmogenesis.

METHOD

A literature review was undertaken to screen for articles that investigated the effects of ROS on cardiac ion channel function, remodeling and arrhythmogenesis.

RESULTS

Prolonged endoplasmic reticulum stress is observed in heart failure, leading to increased production of ROS. Mitochondrial ROS, which is elevated in diabetes and hypertension, can stimulate its own production in a positive feedback loop, termed ROS-induced ROS release. Together with activation of mitochondrial inner membrane anion channels, it leads to mitochondrial depolarization. Abnormal function of these organelles can then activate downstream signaling pathways, ultimately culminating in altered function or expression of cardiac ion channels responsible for generating the cardiac action potential (AP). Vascular and cardiac endothelial cells become dysfunctional, leading to altered paracrine signaling to influence the electrophysiology of adjacent cardiomyocytes. All of these changes can in turn produce abnormalities in AP repolarization or conduction, thereby increasing likelihood of triggered activity and reentry.

CONCLUSION

ROS plays a significant role in producing arrhythmic substrate. Therapeutic strategies targeting upstream events include production of a strong reducing environment or the use of pharmacological agents that target organelle-specific proteins and ion channels. These may relieve oxidative stress and in turn prevent arrhythmic complications in patients with diabetes, hypertension, and heart failure.

Oxidative stress-related biomarkers in essential hypertension and ischemia-reperfusion myocardial damage

Cardiovascular diseases are a leading cause of mortality and morbidity worldwide, with hypertension being a major risk factor. Numerous studies support the contribution of reactive oxygen and nitrogen species in the pathogenesis of hypertension, as well as other pathologies associated with ischemia/reperfusion. However, the validation of oxidative stress-related biomarkers in these settings is still lacking and novel association of these biomarkers and other biomarkers such as endothelial progenitor cells, endothelial microparticles, and ischemia modified albumin, is just emerging. Oxidative stress has been suggested as a pathogenic factor and therapeutic target in early stages of essential hypertension. Systolic and diastolic blood pressure correlated positively with plasma F2-isoprostane levels and negatively with total antioxidant capacity of plasma in hypertensive and normotensive patients. Cardiac surgery with extracorporeal circulation causes an ischemia/reperfusion event associated with increased lipid peroxidation and protein carbonylation, two biomarkers associated with oxidative damage of cardiac tissue. An enhancement of the antioxidant defense system should contribute to ameliorating functional and structural abnormalities derived from this metabolic impairment. However, data have to be validated with the analysis of the appropriate oxidative stress and/or nitrosative stress biomarkers.

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.

Prevention of postoperative atrial fibrillation: novel and safe strategy based on the modulation of the antioxidant system

Postoperative atrial fibrillation (AF) is the most common arrhythmia following cardiac surgery with extracorporeal circulation. The pathogenesis of postoperative AF is multifactorial. Oxidative stress, caused by the unavoidable ischemia-reperfusion event occurring in this setting, is a major contributory factor. Reactive oxygen species (ROS)-derived effects could result in lipid peroxidation, protein carbonylation, or DNA oxidation of cardiac tissue, thus leading to functional and structural myocardial remodeling. The vulnerability of myocardial tissue to the oxidative challenge is also dependent on the activity of the antioxidant system. High ROS levels, overwhelming this system, should result in deleterious cellular effects, such as the induction of necrosis, apoptosis, or autophagy. Nevertheless, tissue exposure to low to moderate ROS levels could trigger a survival response with a trend to reinforce the antioxidant defense system. Administration of n-3 polyunsaturated fatty acids (PUFA), known to involve a moderate ROS production, is consistent with a diminished vulnerability to the development of postoperative AF. Accordingly, supplementation of n-3 PUFA successfully reduced the incidence of postoperative AF after coronary bypass grafting. This response is due to an up-regulation of antioxidant enzymes, as shown in experimental models. In turn, non-enzymatic antioxidant reinforcement through vitamin C administration prior to cardiac surgery has also reduced the postoperative AF incidence. Therefore, it should be expected that a mixed therapy result in an improvement of the cardioprotective effect by modulating both components of the antioxidant system. We present novel available evidence supporting the hypothesis of an effective prevention of postoperative AF including a two-step therapeutic strategy: n-3 PUFA followed by vitamin C supplementation to patients scheduled for cardiac surgery with extracorporeal circulation. The present study should encourage the design of clinical trials aimed to test the efficacy of this strategy to offer new therapeutic opportunities to patients challenged by ischemia-reperfusion events not solely in heart, but also in other organs such as kidney or liver in transplantation surgeries.

Metabolic stress, reactive oxygen species, and arrhythmia

Cardiac arrhythmias can cause sudden cardiac death (SCD) and add to the current heart failure (HF) health crisis. Nevertheless, the pathological processes underlying arrhythmias are unclear. Arrhythmic conditions are associated with systemic and cardiac oxidative stress caused by reactive oxygen species (ROS). In excitable cardiac cells, ROS regulate both cellular metabolism and ion homeostasis. Increasing evidence suggests that elevated cellular ROS can cause alterations of the cardiac sodium channel (Na(v)1.5), abnormal Ca(2+) handling, changes of mitochondrial function, and gap junction remodeling, leading to arrhythmogenesis. This review summarizes our knowledge of the mechanisms by which ROS may cause arrhythmias and discusses potential therapeutic strategies to prevent arrhythmias by targeting ROS and its consequences. This article is part of a Special Issue entitled "Local Signaling in Myocytes".

Myocardial repair/remodelling following infarction: roles of local factors

Heart failure is a global health problem, appearing most commonly in patients with previous myocardial infarction (MI). Cardiac remodelling, particularly fibrosis, seen in both the infarcted and non-infarcted myocardium is recognized to be a major determinant of the development of impaired ventricular function, leading to a poor prognosis. Elucidating cellular and molecular mechanisms responsible for the accumulation of extracellular matrix is essential for designing cardioprotective and reparative strategies that could regress fibrosis after infarction. Multiple factors contribute to left ventricular remodelling at different stages post-MI. This review will discuss the role of oxidative stress and locally produced angiotensin II in the pathogenesis of myocardial repair/remodelling after MI.

Differential effects of all-trans retinoic acid on the growth of human keratinocytes and mouth carcinoma epidermoid cultures. Involvement of GRIM-19 and complex I of the respiratory chain

Squamous cell carcinoma (SSC) is the most frequent malignant tumor of the oral cavity. A study on the effect of all-trans retinoic acid (RA) on cell growth, expression of GRIM-19 and content and activity of complex I of the mitochondrial respiratory chain in normal human keratinocytes (NHEK) and mouth carcinoma cells with low (HN) and high (KB) transformation grade was carried out. In NHEK cells, RA treatment resulted in growth suppression, significant overexpression of GRIM-19 protein, enhanced content of complex I but depressed activity of NADH-UQ oxidoreductase activity of the complex. In HN cells, RA treatment depressed cell growth, inhibited the enzymatic activity of complex I but had no significant effect on the levels of GRIM-19 and complex I. In KB cells RA had no effect on cell growth, GRIM-19 expression, content and activity of complex I.

Expression of Co-stimulatory molecules on langerhans cells in lesional epidermis of human atopic dermatitis

Langerhans cells (LC) are immature dendritic cells (DC) present in the skin epithelium. To understand the molecular and cellular mechanisms governing the inflammatory reaction in atopic dermatitis (AD), the expression of the LC specific marker CD1a, a member of major histocompatibility (MHC)-like glycoproteins, and the co-stimulatory molecules CD80 and CD86, expressed on functionally mature dendritic cells, were counted in lesional biopsies and normal epidermis by an immunohistochemical method. CD1a specific staining was observed in both normal and AD lesion specimens. CD80 and CD86 positive cells with morphological characteristics of the LC were found in lesional AD epidermis, suggesting a high level of functional maturity of these cells and their involvement in chronic inflammatory disease.

Oxidative stress in young subjects with acute myocardial infarction: evaluation at the initial stage and after 12 months

In 105 subjects (97 men and 8 women) aged <46 years (mean age 39.6 +/- 5.5 years), with recent acute myocardial infarction (T1), thiobarbituric acid reactive substances and total antioxidant status were determined; NO production was evaluated by measuring the nitrite and nitrate (NOx) concentration. The patients with acute myocardial infarction were subdivided according to the main risk factors, number of risk factors, and extent of coronary lesions. The evaluation was repeated after 12 months (T2). In these subjects, thiobarbituric acid reactive substances and NOx were significantly increased and total antioxidant status was significantly decreased at T1. In single risk factor, only NO metabolites were significantly lower in acute myocardial infarction subjects who smoke than in subjects who do not. Subdividing the subjects according to the number of risk factors and number of stenosed coronary vessels, there were no significant differences between the subgroups. At T2, thiobarbituric acid reactive substances and NOx were decreased and total antioxidant status was increased, but all parameters were still altered.

Oxidative Stress and Cardiac Repair/Remodeling Following Infarction

Extensive cardiac remodeling after myocardial infarction (MI) contributes significantly to ventricular dysfunction. Factors regulating left ventricular remodeling at different stages after MI are under investigation. There is growing recognition and experimental evidence that oxidative stress mediated by reactive oxygen species plays a role in the pathogeneses of myocardial repair/remodeling in various cardiac diseases. After acute MI, oxidative stress is developed in both infarcted and noninfarcted myocardium. Accumulating evidence has demonstrated that oxidative stress participates in several aspects of cardiac repair/remodeling after infarction that include cardiomyocyte apoptosis, inflammatory/fibrogenic responses, and hypertrophy. The exact pathways on reactive oxygen species-mediated myocardial remodeling are under investigation. The therapeutic potential of oxidative stress-directed drugs in myocardial remodeling after infarction has not been fully realized.

Reperfusion injury as a therapeutic challenge in patients with acute myocardial infarction

Cardiomyocyte death secondary to transient ischemia occurs mainly during the first minutes of reperfusion, in the form of contraction band necrosis involving sarcolemmal rupture. Cardiomyocyte hypercontracture caused by re-energisation and pH recovery in the presence of impaired cytosolic Ca(2+) control as well as calpain-mediated cytoskeletal fragility play prominent roles in this type of cell death. Hypercontracture can propagate to adjacent cells through gap junctions. More recently, opening of the mitochondrial permeability transition pore has been shown to participate in reperfusion-induced necrosis, although its precise relation with hypercontracture has not been established. Experimental studies have convincingly demonstrated that infarct size can be markedly reduced by therapeutic interventions applied at the time of reperfusion, including contractile blockers, inhibitors of Na(+)/Ca(2+) exchange, gap junction blockers, or particulate guanylyl cyclase agonists. However, in most cases drugs for use in humans have not been developed and tested for these targets, while the effect of existing drugs with potential cardioprotective effect is not well established or understood. Research effort should be addressed to elucidate the unsolved issues of the molecular mechanisms of reperfusion-induced cell death, to identify and validate new targets and to develop appropriate drugs. The potential benefits of limiting infarct size in patients with acute myocardial infarction receiving reperfusion therapy are enormous.

Vitamin E: inflammation and atherosclerosis

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the western world with its incidence increasing lately in developing countries. Several lines of evidence support a role for inflammation in atherogenesis. Hence, dietary micronutrients having antiinflammatory properties may have a potential beneficial effect with regard to CVD. Vitamin E is a potent antioxidant with antiinflammatory properties. It comprises eight different isoforms: four tocopherols (T) (alpha, beta, gamma, and delta) and four tocotrienols (T3) (alpha, beta, gamma, and delta). A wealth of data is available for the preventive efficacy of alpha-T. alpha-T supplementation in human subjects and animal models has been shown to be antioxidant and antiinflammatory in terms of decreasing C-reactive protein (CRP) and release of proinflammatory cytokines, the chemokine IL-8 and PAI-1 levels especially at high doses. gamma-T is effective in decreasing reactive nitrogen species and also appears to have antiinflammatory properties; however, there are scanty data examining pure gamma-T preparations. Furthermore, tocotrienols (alpha and gamma) also have implications for prevention of CVD; however, there are conflicting and insufficient data in the literature with regards to their potency. In this chapter, we have gathered recent emerging data on alpha-T specifically and also have given a composite view of gamma-T and tocotrienols especially with regards to their effect on inflammation as it relates to CVD.

Effect of Postconditioning on Coronary Blood Flow Velocity and Endothelial Function and LV Recovery After Myocardial Infarction

OBJECTIVE

Postconditioning is a novel approach to myocardial protection during ischemia reperfusion. Our study observed the effect of postconditioning on coronary blood flow velocity and endothelial function in patients who underwent emergency percutaneous coronary intervention (PCI).

METHODS

Ninety-four patients with their first acute myocardial infarction who underwent revascularization within 12 hours of onset by primary PCI were recruited in the study. All the patients were randomized to two groups, IR group (PCI without postconditioning) and Postcond group (PCI with postconditioning). Corrected TIMI frame count (CTFC) was used to evaluate velocity of coronary blood after PCI. Creatine phosphokinase (CK), CK-MB, and malondialdehyde (MDA) were measured before and after PCI. Arterial endothelial function was studied noninvasively by examination of brachial artery responses to endothelium-dependent and endothelium-independent stimuli by echo Doppler technique. Wall motion score index (WMSI) was assessed by two-dimensional echocardiography before and 8 weeks after angioplasty.

RESULTS

There were no significant differences between the two groups with regard to age, sex, presence of angiographically visible collaterals, and elapsed time from the onset of symptoms until perfusion. Patients with postconditioning had much faster CTFC than patients without postconditioning (25.38 +/- 5.35 vs 29.23 +/- 5.54). After 8 weeks, the WMSI improved significantly in both groups, but the DeltaWMSI in Postcond group was significantly larger than that of IR group (1.20 +/- 0.30 vs 1.04 +/- 0.36, P < 0.05). There was a significant negative correlation between DeltaWMSI and CTFC in IR group and Postcond group (r = -0.9032, P < 0.01; r = -0.7884, P < 0.01). The peaks of CK and CK-MB of Postcond group were much lower than that of IR group (1236.57 +/- 813.21 U/L vs 1697.36 +/- 965.74 U/L; 116.92 +/- 75.83 U/L vs 172.41 +/- 92.64 U/L), and MDA-reactive products were significantly lower than that in the IR group at any same time after PCI. All patients with acute myocardial infarction had a depressed endothelium-dependent vasodilation function, while the endothelium-dependent vasodilation function was improved in Postcond group.

CONCLUSION

Postconditioning is a simple, operative procedure for salvaging the coronary endothelial function and cardiomyocyte. It could be used widely in clinic and to better the prognosis of acute myocardial infarction.