Canine myocardial reperfusion injury. Its reduction by the combined administration of superoxide dismutase and catalase

Initial Despair and Current Hope of Identifying a Clinically Useful Treatment of Myocardial Reperfusion Injury: Insights Derived from Studies of Platelet P2Y12 Antagonists and Interference with Inflammation and NLRP3 Assembly

Myocardial necrosis following the successful reperfusion of a coronary artery occluded by thrombus in a patient presenting with ST-elevation myocardial infarction (STEMI) continues to be a serious problem, despite the multiple attempts to attenuate the necrosis with agents that have shown promise in pre-clinical investigations. Possible reasons include confounding clinical risk factors, the delayed application of protective agents, poorly designed pre-clinical investigations, the possible effects of routinely administered agents that might unknowingly already have protected the myocardium or that might have blocked protection, and the biological differences of the myocardium in humans and experimental animals. A better understanding of the pathobiology of myocardial infarction is needed to stem this reperfusion injury. P2Y12 receptor antagonists minimize platelet aggregation and are currently part of the standard treatment to prevent thrombus formation and propagation in STEMI protocols. Serendipitously, these P2Y12 antagonists also dramatically attenuate reperfusion injury in experimental animals and are presumed to provide a similar protection in STEMI patients. However, additional protective agents are needed to further diminish reperfusion injury. It is possible to achieve additive protection if the added intervention protects by a mechanism different from that of P2Y12 antagonists. Inflammation is now recognized to be a critical factor in the complex intracellular response to ischemia and reperfusion that leads to tissue necrosis. Interference with cardiomyocyte inflammasome assembly and activation has shown great promise in attenuating reperfusion injury in pre-clinical animal models. And the blockade of the executioner protease caspase-1, indeed, supplements the protection already seen after the administration of P2Y12 antagonists. Importantly, protective interventions must be applied in the first minutes of reperfusion, if protection is to be achieved. The promise of such a combination of protective strategies provides hope that the successful attenuation of reperfusion injury is attainable.

Light-specific wavelengths differentially affect the exploration rate, opercular beat, skin color change, opsin transcripts, and the oxi-redox system of the longsnout seahorse Hippocampus reidi

Light is a strong stimulus for the sensory and endocrine systems. The opsins constitute a large family of proteins that can respond to specific light wavelengths. Hippocampus reidi is a near-threatened seahorse that has a diverse color pattern and sexual dimorphism. Over the years, H. reidi's unique characteristics, coupled with its high demand and over-exploitation for the aquarium trade, have raised concerns about its conservation, primarily due to their significant impact on wild populations. Here, we characterized chromatophore types in juvenile and adult H. reidi in captivity, and the effects of specific light wavelengths with the same irradiance (1.20 mW/cm2) on color change, growth, and survival rate. The xanthophores and melanophores were the major components of H. reidi pigmentation with differences in density and distribution between life stages and sexes. In the eye and skin of juveniles, the yellow (585 nm) wavelength induced a substantial increase in melanin levels compared to the individuals kept under white light (WL), blue (442 nm), or red (650 nm) wavelengths. In addition, blue and yellow wavelengths led to a higher juvenile mortality rate in comparison to the other treatments. Adult seahorses showed a rhythmic color change over 24 h, the highest reflectance values were obtained in the light phase, representing a daytime skin lightening for individuals under WL, blue and yellow wavelength, with changes in the acrophase. The yellow wavelength was more effective on juvenile seahorse pigmentation, while the blue wavelength exerted a stronger effect on the regulation of adult physiological color change. Dramatic changes in the opsin mRNA levels were life stage-dependent, which may infer ontogenetic opsin functions throughout seahorses' development. Exposure to specific wavelengths differentially affected the opsins mRNA levels in the skin and eyes of juveniles. In the juveniles, skin transcripts of visual (rh1, rh2, and lws) and non-visual opsins (opn3 and opn4x) were higher in individuals under yellow light. While in the juvenile's eyes, only rh1 and rh2 had increased transcripts influenced by yellow light; the lws and opn3 mRNA levels were higher in juveniles' eyes under WL. Prolonged exposure to yellow wavelength stimulates a robust increase in the antioxidant enzymes sod1 and sod2 mRNA levels. Our findings indicate that changes in the visible light spectrum alter physiological processes at different stages of life in H. reidi and may serve as the basis for a broader discussion about the implications of artificial light for aquatic species in captivity.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

Calpain inhibition decreases oxidative stress via mitochondrial regulation in a swine model of chronic myocardial ischemia

INTRODUCTION

Calpain overexpression is implicated in mitochondrial damage leading to tissue oxidative stress and myocardial ischemic injury. The aim of this study was to determine the effects of calpain inhibition (CI) on mitochondrial impairment and oxidative stress in a swine model of chronic myocardial ischemia and metabolic syndrome.

METHODS

Yorkshire swine were fed a high-fat diet for 4 weeks to induce metabolic syndrome then underwent placement of an ameroid constrictor to the left circumflex artery. Three weeks later, animals received: no drug (control, "CON"; n= 7); a low-dose calpain inhibitor (0.12 mg/kg; "LCI", n= 7); or high-dose calpain inhibitor (0.25 mg/kg; "HCI", n=7). Treatment continued for 5 weeks, followed by tissue harvest. Cardiac tissue was assayed for protein carbonyl content, as well as antioxidant and mitochondrial protein expression. Reactive oxygen species (ROS) and mitochondrial respiration was measured in H9c2 cells following exposure to normoxia or hypoxia (1%) for 24 h with or without CI.

RESULTS

In ischemic myocardial tissue, CI was associated with decreased total oxidative stress compared to control. CI was also associated with increased expression of mitochondrial proteins superoxide dismutase 1, SDHA, and pyruvate dehydrogenase compared to control. 100 nM of calpain inhibitor decreased ROS levels and respiration in both normoxic and hypoxic H9c2 cardiomyoblasts.

CONCLUSIONS

In the setting of metabolic syndrome, CI improves oxidative stress in chronically ischemic myocardial tissue. Decreased oxidative stress may be via modulation of mitochondrial proteins involved in free radical scavenging and production.

Oxidative Stress, Antioxidants and Hypertension

As a major cause of morbidity and mortality globally, hypertension remains a serious threat to global public health. Despite the availability of many antihypertensive medications, several hypertensive individuals are resistant to standard treatments, and are unable to control their blood pressure. Regulation of the renin-angiotensin-aldosterone system (RAAS) controlling blood pressure, activation of the immune system triggering inflammation and production of reactive oxygen species, leading to oxidative stress and redox-sensitive signaling, have been implicated in the pathogenesis of hypertension. Thus, besides standard antihypertensive medications, which lower arterial pressure, antioxidant medications were tested to improve antihypertensive treatment. We review and discuss the role of oxidative stress in the pathophysiology of hypertension and the potential use of antioxidants in the management of hypertension and its associated organ damage.

Protective Effect of Ebselen on Ischemia-reperfusion Injury in Epigastric Skin Flaps in Rats

The purpose of this study was to determine the role of oxidized diacylglycerol (DAG) and the molecular mechanism underlying ischemia-reperfusion (I/R) injury in rat skin flaps. The protective effect of ebselen on the viability of rat skin flaps with I/R injury was investigated. Flaps were designed and raised in the left inguinal region. Then, a microvascular clamp was applied to the vascular pedicle and reperfused after 6 hr. After 7 days of I/R (I/R group), the skin flap survival area ratio was significantly reduced compared to the normal skin. The administration of ebselen significantly improved the ratio compared to the I/R group. The flap survival area ratio of the I/R + ebselen group was significantly improved compared to the I/R + vehicle group. In the I/R + ebselen group, the oxidized DAG content and intensity of phosphorylated PKCα and PKCδ were significantly lower compared to the I/R + vehicle group. Furthermore, the inflammatory response was suppressed in the I/R + ebselen group compared to the I/R + vehicle group. These results indicate that ebselen is useful as a preventive and therapeutic agent for skin flap necrosis caused by I/R, because of reduction and elimination of oxidized DAG.

Early Doxorubicin Myocardial Injury: Inflammatory, Oxidative Stress, and Apoptotic Role of Galectin-3

Doxorubicin (DOXO) is an effective drug that is used in the treatment of a large number of cancers. Regardless of its important chemotherapeutic characteristics, its usage is restricted because of its serious side effects; the most obvious is cardiotoxicity, which can manifest acutely or years after completion of treatment, leading to left ventricular dysfunction, dilated cardiomyopathy, and heart failure. Galectin 3 (Gal-3) is a beta galactoside binding lectin that has different roles in normal and pathophysiological conditions. Gal-3 was found to be upregulated in animal models, correlating with heart failure, atherosclerosis, and myocardial infarction. Male C57B6/J and B6.Cg-Lgals3 <tm 1 Poi>/J Gal-3 knockout (KO) mice were used for a mouse model of acute DOXO-induced cardiotoxicity. Mice were given DOXO or vehicle (normal saline), after which the mice again had free access to food and water. Heart and plasma samples were collected 5 days after DOXO administration and were used for tissue processing, staining, electron microscopy, and enzyme-linked immunosorbent assay (ELISA). There was a significant increase in the heart concentration of Gal-3 in Gal-3 wild type DOXO-treated mice when compared with the sham control. There were significantly higher concentrations of heart cleaved caspase-3, plasma troponin I, plasma lactate dehydrogenase, and plasma creatine kinase in Gal-3 KO DOXO-treated mice than in Gal-3 wild type DOXO-treated mice. Moreover, there were significantly higher heart antioxidant proteins and lower oxidative stress in Gal-3 wild type DOXO-treated mice than in Gal-3 KO DOXO-treated mice. In conclusion, Gal-3 can affect the redox pathways and regulate cell survival and death of the myocardium following acute DOXO injury.

Effect of Oxygen Free Radicals on Cardiac Contractile Activity and Sarcolemmal Na+–Ca2+Exchange

Background

Although oxygen free radicals have been shown to induce myocardial cell damage and cardiac dysfunction, the exact mechanism by which these radicals affect the heart function is not clear. Since the occurrence of intracellular Ca2+overload is critical in the genesis of cellular damage and cardiac dysfunction, and since the sarcolemmal Na+–Ca2+exchange is intimately involved in Ca2+movements in myocardium, this study was undertaken to examine the effects of oxygen free radicals on the relationship between changes in cardiac contractile force development and sarcolemmal Na+–Ca2+exchange activity.

Methods and Results

Isolated rat hearts were perfused with a medium containing xanthine plus xanthine oxidase for different times, and changes in contractile force as well as sarcolemmal Na+–Ca2+exchange activity were monitored. Perfusion of the heart with xanthine plus xanthine oxidase resulted in a transient increase followed by a marked decrease in contractile activity; the resting tension was markedly increased. The xanthine plus xanthine oxidase-induced depression in developed tension, rate of contraction, and rate of relaxation, except the transient increase in contractile activity, was prevented by the addition of catalase, but not by superoxide dismutase, in the perfusion medium. A time-dependent depression in sarcolemmal Na+–Ca2+was also evident upon perfusing the heart with xanthine plus xanthine oxidase. This depression in Na+-dependent Ca2+uptake was associated with a decrease in the maximal velocity of reaction without any changes in the affinity of Na+–Ca2+exchanger for Ca2+. The presence of catalase, unlike superoxide dismutase, prevented the decrease in sarcolemmal Na+–Ca2+exchange activity in hearts perfused with xanthine plus xanthine oxidase.

Conclusion

The results support the view that a depression in the sarcolemmal Na+–Ca2+exchange activity may contribute to the occurrence of intracellular Ca2+overload and subsequent decrease in contractile activity. Furthermore, these actions of xanthine plus xanthine oxidase in the whole heart appear to be a consequence of H2O2production rather than the ‘ generation of superoxide radicals.

Reperfusion injury as a target for diminishing infarct size

Therapies for preventing reperfusion injury (RI) have been widely studied. However, the attempts to transfer cardioprotective therapies for reducing RI from experiments into clinical practice have been so far unsuccessful. Pathophysiological mechanisms of RI are complicated and compose of many pathways e.g. hypercontracture-mediated sarcolemma rupture, mitochondrial permeability transition pore persistent opening, reactive oxygen species formation, inflammation and no-reflow phenomenon. Based on research, it cannot be determined which mechanism dominates, probably they cooperate with a domination of one or another in different clinical circumstances. Our hypothesis is, that only intervention that at the same time interferes with different (all?) pathways of RI may turn out to be effective in decreasing the final area of infarction.

Evaluation of Free Radical Injury in Myocardium

Abundant evidence now is available that free radicals are produced in excess when myocardium is reperfused following an episode of ischemia and that free radicals can injure myocytes and endothelial cells. Free radicals may contribute to either reversible or irreversible manifestations of cell injury from ischemia and reperfusion. Several investigators have observed that postischemic contractile dysfunction (myocardial stunning) can be attenuated by a variety of anti-free radical therapies, and there seems to be general agreement that free radical injury contributes to stunning. Whether free radicals are an important cause of lethal myocyte injury (“lethal reperfusion injury”) remains controversial. Using similar interventions and animal models, both positive and negative results have been reported from a growing number of studies done to test the effect of anti-free radical therapies on infarct size. Proposed explanations include differences in: 1) dose of drug and onset or duration of treatment, 2) duration of occlusion or reperfusion, 3) methods of measuring infarct size or area at risk, and 4) failure of some studies to control for baseline variation in the major determinants of infarct size, e.g., collateral blood flow. At present, none of these explanations seems sufficient to resolve the question.

Fundamentals of the modern theory of the phenomenon of "pain" from the perspective of a systematic approach. Neurophysiological basis. Part 1: A brief presentation of key subcellular and cellular ctructural elements of the central nervous system

The phenomenon of “pain” is a psychophysiological phenomenon that is actualized in the mind of a person as a result of the systemic response of his body to certain external and internal stimuli. The heart of the corresponding mental processes is certain neurophysiological processes, which in turn are caused by a certain form of the systemic structural and functional organization of the central nervous system (CNS). Thus, the systemic structural and functional organization of the central nervous system of a person, determining the corresponding psychophysiological state in a specific time interval, determines its psycho-emotional states or reactions manifested by the pain phenomenon. The nervous system of the human body has a hierarchical structure and is a morphologically and functionally complete set of different, interconnected, nervous and structural formations. The basis of the structural formations of the nervous system is nervous tissue. It is a system of interconnected differentials of nerve cells, neuroglia and glial macrophages, providing specific functions of perception of stimulation, excitation, generation of nerve impulses and its transmission. The neuron and each of its compartments (spines, dendrites, catfish, axon) is an autonomous, plastic, active, structural formation with complex computational properties. One of them – dendrites – plays a key role in the integration and processing of information. Dendrites, due to their morphology, provide neurons with unique electrical and plastic properties and cause variations in their computational properties. The morphology of dendrites: 1) determines – a) the number and type of contacts that a particular neuron can form with other neurons; b) the complexity, diversity of its functions; c) its computational operations; 2) determines – a) variations in the computational properties of a neuron (variations of the discharges between bursts and regular forms of pulsation); b) back distribution of action potentials. Dendritic spines can form synaptic connection – one of the main factors for increasing the diversity of forms of synaptic connections of neurons. Their volume and shape can change over a short period of time, and they can rotate in space, appear and disappear by themselves. Spines play a key role in selectively changing the strength of synaptic connections during the memorization and learning process. Glial cells are active participants in diffuse transmission of nerve impulses in the brain. Astrocytes form a three-dimensional, functionally “syncytia-like” formation, inside of which there are neurons, thus causing their specific microenvironment. They and neurons are structurally and functionally interconnected, based on which their permanent interaction occurs. Oligodendrocytes provide conditions for the generation and transmission of nerve impulses along the processes of neurons and play a significant role in the processes of their excitation and inhibition. Microglial cells play an important role in the formation of the brain, especially in the formation and maintenance of synapses. Thus, the CNS should be considered as a single, functionally “syncytia-like”, structural entity. Because the three-dimensional distribution of dendritic branches in space is important for determining the type of information that goes to a neuron, it is necessary to consider the three-dimensionality of their structure when analyzing the implementation of their functions.

Enhancing the activity and stability of Mn-superoxide dismutase by one-by-one ligation to catalase

Dismutation of superoxide by superoxide dismutase (SOD) generates hydrogen peroxide, which may be reduced to hydroxyl radical. The generated H₂O₂ during the catalysis can have an oxidative damage to SOD. Hydrogen peroxide decomposition by catalase (CAT) can help circumvent the problem. Mn-superoxide dismutase (herein referred to as SOD) and CAT are dimeric and tetrameric proteins, respectively. Herein, through intein-mediated in vivo subunit splicing, the C-terminus of the CAT subunit (CAT^S) has been specifically ligated to the N-terminus of the SOD subunit (SOD^S) with a peptide bond. Thus, the splicing product SOD&CAT combines the superoxide anion (•O₂^-) scavenging ability and the ability of decomposing H₂O₂. The in vivo subunit splicing has little effect on the secondary structures of the enzymes as confirmed by circular dichroism (CD) spectra. Fluorescence spectra showed that the splicing product SOD&CAT has a higher stability than SOD. In the splicing product SOD&CAT, the SOD subunits are in close proximity to the CAT subunits, facilitating immediate transfer of H₂O₂ between the enzymes and enabling efficient decomposition of H₂O₂. SOD&CAT exhibited a superoxide anion (•O₂^-) scavenging ability 244% higher than that of SOD and 46% higher than that of the mixed enzymes SOD+CAT.

Anti-ageing skin effects of Korean bamboo salt on SKH1 hairless mice

Bamboo salt is generated by baking bamboo and sea salt and is used as a traditional food or medicine. The aim of this study was to investigate the anti-ageing skin effects of Korean bamboo salt and to compare the antioxidant, anti-ageing and anti-inflammatory effects of various salts, including purified salt, solar salt, bath solar salt, Masada solar salt, 1-time baked bamboo salt (1× bamboo salt), and 9-times baked bamboo salt (9× bamboo salt). Based on the content of mineral elements, pH, OH groups and redox potential amperometric analysis, the 9× bamboo salt showed the most antioxidant components and characteristics compared to the other salts. The in vitro results showed that the 9× bamboo salt could inhibit oxidative damage by hydrogen peroxide (H₂O₂) treatment in HaCaT keratinocytes, and its effect was better than that of the other salts. In an in vivo experiment, SHK-1 hairless mice were treated with UV (ultraviolet) radiation to induce ageing. The epidermal thickness and epidermal structures were then assessed by phenotypic and histological analyses. The 0.2% 9× bamboo salt- and 1× bamboo salt-treated mice had a thinner epidermis than the control mice, and the sebaceous glands were almost intact with a regular arrangement that was similar to those in the normal group. Compared with the UV-treated group (control group) and other salt-treated groups, the 9× bamboo salt- and 1× bamboo salt-treated groups had higher dermal collagen and elastic fibre content. Fewer mast cells were observed in the 9× bamboo salt- and 1× bamboo salt-treated groups than in the control group. The activities of the skin antioxidant-related enzymes superoxide dismutase (SOD) and catalase (CAT) in the 9× bamboo salt- and 1× bamboo salt-treated groups were higher than those in other groups and similar to those in the normal group, but lipid peroxide (LPO) activity and carbonylated protein levels showed the opposite trends. Furthermore, the 9× bamboo salt- and 1× bamboo salt-treated groups had protein contents similar to those of the normal group. In addition, the 9× bamboo salt and 1× bamboo salt effectively down-regulated the expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) and up-regulated the expression of tissue inhibitor expression of matrix metalloproteinase-1 (TIMP-1), matrix metalloproteinase-2 (TIMP-2), SOD and CAT compared to the other salts at a concentration of 0.2% (p < 0.05). These results suggest that at appropriate concentrations, bamboo salt could prevent skin ageing induced by ultraviolet radiation b (UVB) photodamage.

Evans Blue Dye: A Revisit of Its Applications in Biomedicine

Evans blue (EB) dye has owned a long history as a biological dye and diagnostic agent since its first staining application by Herbert McLean Evans in 1914. Due to its high water solubility and slow excretion, as well as its tight binding to serum albumin, EB has been widely used in biomedicine, including its use in estimating blood volume and vascular permeability, detecting lymph nodes, and localizing the tumor lesions. Recently, a series of EB derivatives have been labeled with PET isotopes and can be used as theranostics with a broad potential due to their improved half-life in the blood and reduced release. Some of EB derivatives have even been used in translational applications in clinics. In addition, a novel necrosis-avid feature of EB has recently been reported in some preclinical animal studies. Given all these interesting and important advances in EB study, a comprehensive revisiting of EB has been made in its biomedical applications in the review.

Significance of oxygen free radicals in the pathophysiology of hemorrhagic shock - A protocol

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Free radicals can cause significant tissue damage.

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Scavengers of free radicals are a useful way to reduce reperfusion injury.

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Electron Paramagnetic Resonance (EPR) spectroscopy is the best way to detect free radicals.

Oxygen free radicals have been implicated as the deleterious agent in a variety of organ systems undergoing ischemia and subsequent reperfusion. Hemorrhagic shock represents a clinical situation that carries a high rate of morbidity and mortality despite adequate fluid resuscitation. Since this entity represents, in its most simplified sense, total body ischemia followed by reperfusion, it is likely that the generation of oxygen free radicals has some significance in the pathophysiology of this delayed morbidity. This is a research protocol, where rabbits will be subjected to severe hemorrhagic shock followed by adequate fluid resuscitation. In the first part of the experiment, free radical generation will be measured directly by Electron Paramagnetic Resonance (EPR) spectroscopy in various organ systems in rabbits before and during shock, and following resuscitation. In the second part, free radical scavengers will be introduced as an adjunct to fluid resuscitation in a group of rabbits subjected to hemorrhagic shock to see if mortality rates are affected. By acquiring a better understanding of the molecular mechanisms that may be responsible for the delayed morbidity in reperfusion injury in general, and hemorrhagic shock in particular, we will be able to better address the long-standing problem of multi system organ failure (MSOF) that often follows a successful resuscitation.

NEDD4-1 protects against ischaemia/reperfusion-induced cardiomyocyte apoptosis via the PI3K/Akt pathway

Activation of the Akt pathway has been shown to protect the heart from ischaemia/reperfusion (I/R) injury. NEDD4-1 has been shown to positively regulate nuclear trafficking of the activated form of Akt. However, the role of NEDD4-1 in cardiac I/R injury remains to be elucidated. In the present study, Lentiviral vectors were constructed to overexpress or knockdown NEDD4-1 in H9c2 cardiomyocytes subjected to I/R injury or ischemic preconditioning (IPC). The results indicated that NEDD4-1 levels were decreased after I/R and increased after IPC in rat heart tissue and in H9c2 cardiomyocytes. Overexpression of NEDD4-1 activated the Akt pathway and regulated apoptosis-related proteins in H9c2 cardiomyocytes, attenuating SI/R-induced cell apoptosis and caspase 3/7 activities. Furthermore, in vivo overexpression of NEDD4-1 attenuated myocardial apoptosis following myocardial I/R. Our results demonstrated that NEDD4-1 protects the myocardium from I/R induced apoptosis by activating PI3K/Akt signaling.

Oxidative stress causes hypertension and activation of nuclear factor-κB after high-fructose and salt treatments

There is evidence that diets rich in salt or simple sugars as fructose are associated with abnormalities in blood pressure regulation. However, the mechanisms underlying pathogenesis of salt- and fructose-induced kidney damage and/or consequent hypertension yet remain largely unexplored. Here, we tested the role of oxidative state as an essential factor along with high salt and fructose treatment in causing hypertension. Fischer male rats were supplemented with a high-fructose diet (20% in water) for 20 weeks and maintained on high-salt diet (8%) associate in the last 10 weeks. Fructose-fed rats exhibited a salt-dependent hypertension accompanied by decrease in renal superoxide dismutase activity, which is the first footprint of antioxidant inactivation by reactive oxygen species (ROS). Metabolic changes and the hypertensive effect of the combined fructose-salt diet (20 weeks) were markedly reversed by a superoxide scavenger, Tempol (10 mg/kg, gavage); moreover, Tempol (50 mM) potentially reduced ROS production and abolished nuclear factor-kappa B (NF-κB) activation in human embryonic kidney HEK293 cells incubated with L-fructose (30 mM) and NaCl (500 mosmol/kg added). Taken together, our data suggested a possible role of oxygen radicals and ROS-induced activation of NF-κB in the fructose- and salt-induced hypertension associated with the progression of the renal disease.

Antioxidant Activity of SOD and Catalase Conjugated with Nanocrystalline Ceria

Interactions of nanoparticles with biological matter-both somatically and in nature-draw scientists' attention. Nanoparticulate systems are believed to be our saviors, acting as versatile drug delivery vehicles. However, they can also cause life-threatening bodily damage. One of the most important properties of nanocrystalline cerium dioxide is its antioxidant activity, which decreases the abundance of reactive oxygen species during inflammation. In this paper, we report on synergistic effects of inorganic cerium oxide (IV) nanoparticles conjugated with the antioxidative enzymes superoxide dismutase and catalase on scavenging oxygen and nitrogen radicals.

Generation of Free Radicals During Cold Injury and Rewarming

Cold injury is often associated with irreversible cell damage. At present, however, the pathophysiology of cold injury is not known. This study examines the mechanism of such injury. New Zealand white rabbits were anesthetized and their femoral artery and vein were exposed. After baseline measurements one hind limb was cooled with a freezing mixture to 0°C, followed by rewarming. The other hind limb served as control. During the experiment blood samples were withdrawn from the femoral artery and vein for the subsequent analysis of creatine kinase (CK), lactate dehydrogenase (LDH), and malonaldehyde (MDA). At the end salicylate was injected through the femoral vein to trap any hydroxyl radical (OH°) formed. Rabbits were immediately sacrificed, and biop sies were withdrawn and frozen at liquid nitrogen temperature for analysis of OH° and high-energy phosphate compounds.

The results indicate that local blood flow in the cold-exposed hind limb was reduced significantly, suggesting that cold injury was associated with ischemic insult. CK and LDH increased after cold exposure and increased further during rewarming. MDA formation followed a similar pattern. OH° generated after cooling increased significantly upon rewarming. These results indicate that re warming is associated with an episode of ischemia/reperfusion with simultane ous generation of free radicals, which, at least in part, may be responsible for cellular injury associated with rewarming.

Lipid Peroxides in the Mechanism of Ischemia/Reperfusion Injury in Skeletal Muscle—Experimental Studies

Two sets of experiments were conducted to investigate whether oxygen-de rived free radicals are involved in the mechanism of ischemia/reperfusion (I/R) injury of skeletal muscle and vitamin E is effective in alleviating the injury.

In the first set of experiments, twenty adult mongrel dogs were divided into three groups: group 1 (n=7) control, group 2 (n = 6) I/R, and group 3 (n=7) I/R with 500 mg of vitamin E. Serum creatine phosphokinase (CPK) and lipid per oxides (LPO) were measured as markers of rhabdomyolysis and biomembrane injury due to oxygen-derived free radicals, respectively. CPK increased signifi cantly after reperfusion with a peak value of 38,000 ± 9,800 mU/mL in group 2, when compared with a peak value of 1,060 ± 290 mU/mL in group 3 (p < 0.02). LPO also significantly increased with a peak value of 20.4 ±3.7 nmol/mL in group 2, when compared with a peak value of 9.2 ± 2.2 nmol/mL in group 3 (p < 0.04).

In the second sets of experiments, 13 dogs were divided into two groups: group A (n=5) control and group B (n=8) I/R. Tissue LPO was measured eighteen hours after reperfusion in the gracilis muscle and gastrocnemius mus cle. The mean value of LPO in the gracilis muscle was 0.94 ± 0.46 nmol/mg protein in group A, compared with 1.13 ± 0.67 nmol/mg protein in group B. It was higher in group B, but there was no significant difference. Mean LPO in the gastrocnemius muscle was 0.85 ± 0.34 nmol/mg protein in group A, and 1.83 ± 0.71 nmol/mg protein in group B. There was a significant difference (p < 0.02).

Serum CPK and LPO were significantly higher in group 2 than in groups 1 and 3, and tissue LPO was also high in skeletal muscle after reperfusion. Serum CPK and LPO were effectively suppressed by administration of vitamin E be fore reperfusion.

These results show that oxygen-derived free radicals are involved in the mechanism of I/R injury in skeletal muscle and suggest that vitamin E is effec tive in alleviating the injury.

Aliskiren - a promising strategy for ovarian ischemia/reperfusion injury protection in rats via RAAS

The aim of this study was to evaluate the effects of aliskiren, direct renin inhibitor, as an antioxidant and tissue protective agent and evaluate the molecular, biochemical, and histopathological changes in experimental ischemia and ischemia/reperfusion injury in rat ovaries. Forty-eight female rats were randomly divided into eight groups: in Group 1, only sham operation was performed. Group 2 received 100 mg/kg aliskiren and sham operated. In Group 3, 3 h-period of bilateral ovarian ischemia was applied. Group 4 received a 3-h period of ischemia followed by 3 h of reperfusion. Groups 5 and 6 received 50 and 100 mg/kg, respectively, of aliskiren and bilateral ovarian ischemia was applied (after a 3-h period of ischemia, both ovaries were surgically removed). To Groups 7 and 8, 50 and 100 mg/kg of aliskiren were administered, respectively, and the induction of ischemia was performed. At the end of a 3-h period of ischemia, bilateral vascular clips were removed, and 3 h of reperfusion continued. After the experiments, IL-1β, IL-6, TNF-α, and iNOS mRNA expressions and SOD, GSH, MDA, renin, and angiotensin-II levels were determined and histopathological changes were examined in rat ovaries. Aliskiren treatment normalized excessive changes in cytokine and oxidative stress markers in both ischemia and ischemia/reperfusion injury. Histopathologically, treatment with aliskiren ameliorated the development of ischemia and/or ischemia/reperfusion tissue injury. This study concluded that aliskiren treatment is effective in reversing ischemia and/or ischemia/reperfusion induced ovary damage via the improvement of oxidative stress, reduction of inflammation, and suppression of the renin-angiotensin aldosterone system.

Plasma-derived Extracellular Vesicles Contain Predictive Biomarkers and Potential Therapeutic Targets for Myocardial Ischemic (MI) Injury

Myocardial infarction (MI) triggers a potent inflammatory response via the release of circulatory mediators, including extracellular vesicles (EVs) by damaged cardiac cells, necessary for myocardial healing. Timely repression of inflammatory response are critical to prevent and minimize cardiac tissue injuries, nonetheless, progression in this aspect remains challenging. The ability of EVs to trigger a functional response upon delivery of carried bioactive cargos, have made them clinically attractive diagnostic biomarkers and vectors for therapeutic interventions. Using label-free quantitative proteomics approach, we compared the protein cargo of plasma EVs between patients with MI and from patients with stable angina (NMI). We report, for the first time, the proteomics profiling on 252 EV proteins that were modulated with >1.2-fold after MI. We identified six up-regulated biomarkers with potential for clinical applications; these reflected post-infarct pathways of complement activation (Complement C1q subcomponent subunit A (C1QA), 3.23-fold change, p = 0.012; Complement C5 (C5), 1.27-fold change, p = 0.087), lipoprotein metabolism (Apoliporotein D (APOD), 1.86-fold change, p = 0.033; Apolipoprotein C-III (APOCC3), 2.63-fold change, p = 0.029) and platelet activation (Platelet glycoprotein Ib alpha chain (GP1BA), 9.18-fold change, p < 0.0001; Platelet basic protein (PPBP), 4.72-fold change, p = 0.027). The data have been deposited to the ProteomeXchange with identifier PXD002950. This novel biomarker panel was validated in 43 patients using antibody-based assays (C1QA (p = 0.005); C5 (p = 0.0047), APOD (p = 0.0267); APOC3 (p = 0.0064); GP1BA (p = 0.0031); PPBP (p = 0.0465)). We further present that EV-derived fibrinogen components were paradoxically down-regulated in MI, suggesting that a compensatory mechanism may suppress post-infarct coagulation pathways, indicating potential for therapeutic targeting of this mechanism in MI. Taken together, these data demonstrated that plasma EVs contain novel diagnostic biomarkers and therapeutic targets that can be further developed for clinical use to benefit patients with coronary artery diseases (CADs).

Role of JAK-STAT pathway in reducing cardiomyocytes hypoxia/reoxygenation injury induced by S1P postconditioning

This experiment was designed to explore the protection of sphingosine1-phosphate (S1P) postconditioning on rat myocardial cells injured by hypoxia/reoxygenation acting via the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signal pathway. The data showed that S1P could significantly increase cell viability, lower the rate of apoptosis, decrease the content of lactate dehydrogenase (LDH) and caspase3 activity in the culture medium, increase the activity of total superoxide dismutase (T-SOD) and manganese superoxide dismutase (Mn-SOD), reduce the loss of mitochondrial membrane potential and the fluorescence intensity of intracellular calcium, as well as increase the phosphorylation of JAK2 and STAT3 in comparison with the H/R group. When the JAK inhibitor AG490 or the STAT inhibitor stattic were added, the effects of S1P were inhibited. Our date shows that S1P protects H9c2 cells from hypoxia/reoxygenation injury and that the protection by S1P was inhibited by AG490 and stattic. Therefore S1P protects H9c2 cells against hypoxia/reoxygenation injury via the JAK-STAT pathway.

Efficacy of the superoxide dismutase mimetic tempol in animal hypertension models: a meta-analysis

OBJECTIVE

Considering the growing body of evidence that indicates the contribution of superoxide anions (O2) and other reactive oxygen species (ROS) to the development of hypertension, we assessed whether animal models of hypertension have a benefic effect with tempol, a superoxide dismutase mimetic, to help augment the design of future studies.

METHODS

Studies published between July 1998 and December 2012 on blood pressure (BP) in different hypertensive models were obtained after an electronic and manual search of PubMed. In-depth analyses of the methodological quality of the studies and the mean arterial pressure (MAP) changes after treatment with tempol were performed, as well as the subgroup analyses on the route of tempol delivery.

RESULTS

Out of the 144 identified studies, 28 were included after screening. The data showed that tempol reduced MAP by computing the standardized mean difference with the value of 4.622 (95% confidence interval 3.24-5.99). The quality of studies included in the meta-analysis was category II; however, omission of details in the trials might have biased the results. There was substantial heterogeneity in the results with an I of 94.45%, which persisted after stratifying for the route of tempol delivery.

CONCLUSION

In conclusion, this analysis shows that antioxidant treatment with tempol can reduce BP, suggesting that ROS plays a role in the pathogenesis of increased BP in the hypertension models used in the current research practice.

Intravenous Administration of Lycopene, a Tomato Extract, Protects against Myocardial Ischemia-Reperfusion Injury

Background: Oral uptake of lycopene has been shown to be beneficial for preventing myocardial ischemia-reperfusion (I/R) injury. However, the strong first-pass metabolism of lycopene influences its bioavailability and impedes its clinic application. In this study, we determined an intravenous (IV) administration dose of lycopene protects against myocardial infarction (MI) in a mouse model, and investigated the effects of acute lycopene administration on reactive oxygen species (ROS) production and related signaling pathways during myocardial I/R. Methods: In this study, we established both in vitro hypoxia/reoxygenation (H/R) cell model and in vivo regional myocardial I/R mouse model by ligating left anterior artery descending. TTC dual staining was used to assess I/R induced MI in the absence and presence of acute lycopene administration via tail vein injection. Results: Lycopene treatment (1 μM) before reoxygenation significantly reduced cardiomyocyte death induced by H/R. Intravenous administration of lycopene to achieve 1 μM concentration in circulating blood significantly suppressed MI, ROS production, and JNK phosphorylation in the cardiac tissue of mice during in vivo regional I/R. Conclusion: Elevating circulating lycopene to 1 μM via IV injection protects against myocardial I/R injury through inhibition of ROS accumulation and consequent inflammation in mice.

Post-myocardial infarct inflammation and the potential role of cell therapy

Myocardial infarction triggers reparative inflammatory processes programmed to repair damaged tissue. However, often additional injury to the myocardium occurs through the course of this inflammatory process, which ultimately can lead to heart failure. The potential beneficial effects of cell therapy in treating cardiac ischemic disease, the number one cause of death worldwide, are being studied extensively, both in clinical trials using adult stem cells as well as in fundamental research on cardiac stem cells and regenerative biology. This review summarizes the current knowledge on molecular and cellular processes implicated in post-infarction inflammation and discusses the potential beneficial role cell therapy might play in this process. Due to its immunomodulatory properties, the mesenchymal stromal cell is a candidate to reverse the disease progression of the infarcted heart towards heart failure, and therefore is emphasized in this review.

Signalling pathways and mechanisms of protection in pre- and postconditioning: historical perspective and lessons for the future

Ischaemic pre- and postconditioning are potent cardioprotective interventions that spare ischaemic myocardium and decrease infarct size after periods of myocardial ischaemia/reperfusion. They are dependent on complex signalling pathways involving ligands released from ischaemic myocardium, G-protein-linked receptors, membrane growth factor receptors, phospholipids, signalling kinases, NO, PKC and PKG, mitochondrial ATP-sensitive potassium channels, reactive oxygen species, TNF-α and sphingosine-1-phosphate. The final effector is probably the mitochondrial permeability transition pore and the signalling produces protection by preventing pore formation. Many investigators have worked to produce a roadmap of this signalling with the hope that it would reveal where one could intervene to therapeutically protect patients with acute myocardial infarction whose hearts are being reperfused. However, attempts to date to show efficacy of such an intervention in large clinical trials have been unsuccessful. Reasons for this inability to translate successes in the experimental laboratory to the clinical arena are evaluated in this review. It is suggested that all patients with acute coronary syndromes currently presenting to the hospital and being treated with platelet P2Y12 receptor antagonists, the current standard of care, are indeed already benefiting from protection from the conditioning pathways outlined earlier. If that proves to be the case, then future attempts to further decrease infarction will have to rely on interventions which protect by a different mechanism.

Strophanthus hispidus attenuates the Ischemia-Reperfusion induced myocardial Infarction and reduces mean arterial pressure in renal artery occlusion

Background:

The myocardium is generally injured in the case of reperfusion injury and arterial damage is caused by hypertension. In reference to these statements, the present study was focused. Cardiac glycosides were said to have protective effects against myocardial infarction and hypertension. Strophanthus hispidus was thus incorporated in the study.

Objective:

The prime objective of the study was to investigate the protective effects of Strophanthus hispidus against ischemia-reperfusion myocardial Infarction and renal artery occluded hypertension in rats.

Materials and Methods:

The animal model adopted was surgically-induced myocardial ischemia, performed by means of left anterior descending coronary artery occlusion (LAD) for 30 min followed by reperfusion for another 4 h. Infarct size was assessed by using the staining agent TTC (2,3,5-triphenyl tetrazolium chloride). Hypertension was induced by clamping the renal artery with renal bulldog clamp for 4 h.

Results:

The study was fruitful by the effect of Strophanthus hispidus on infarction size, which got reduced to 27.2 ± 0.5and 20.0 ± 0.2 by 500 mg/Kg and 1000 mg/Kg ethanolic extracts which was remarkably significant when compared with that of the control group 52.8 ± 4.6. The plant extract did reduce heart rate at various time intervals. There was also a protective effect in the case of mean arterial blood pressure were the 500 mg/Kg and 1000 mg/Kg of the plant extract did reduce the hypertension after 60 minutes was 60.0 ± 4.80 and 50.50 ± 6.80.

Conclusion:

The results suggest that 500 mg/Kg and 100 mg/Kg ethanolic extract of Strophanthus hispidus was found to possess significant cardiac protective and anti-hypertensive activity.

Mitochondrial reactive oxygen species (ROS) and ROS-induced ROS release

Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to redox stress may involve mitochondrial channels such as mPTP and inner membrane anion channel (IMAC). Their activation causes intra- and intermitochondrial redox-environment changes leading to ROS release. This regenerative cycle of mitochondrial ROS formation and release was named ROS-induced ROS release (RIRR). Brief, reversible mPTP opening-associated ROS release apparently constitutes an adaptive housekeeping function by the timely release from mitochondria of accumulated potentially toxic levels of ROS (and Ca(2+)). At higher ROS levels, longer mPTP openings may release a ROS burst leading to destruction of mitochondria, and if propagated from mitochondrion to mitochondrion, of the cell itself. The destructive function of RIRR may serve a physiological role by removal of unwanted cells or damaged mitochondria, or cause the pathological elimination of vital and essential mitochondria and cells. The adaptive release of sufficient ROS into the vicinity of mitochondria may also activate local pools of redox-sensitive enzymes involved in protective signaling pathways that limit ischemic damage to mitochondria and cells in that area. Maladaptive mPTP- or IMAC-related RIRR may also be playing a role in aging. Because the mechanism of mitochondrial RIRR highlights the central role of mitochondria-formed ROS, we discuss all of the known ROS-producing sites (shown in vitro) and their relevance to the mitochondrial ROS production in vivo.

Over-expression of catalase in myeloid cells confers acute protection following myocardial infarction

Cardiovascular disease is the leading cause of death in the United States and new treatment options are greatly needed. Oxidative stress is increased following myocardial infarction and levels of antioxidants decrease, causing imbalance that leads to dysfunction. Therapy involving catalase, the endogenous scavenger of hydrogen peroxide (H₂O₂), has been met with mixed results. When over-expressed in cardiomyocytes from birth, catalase improves function following injury. When expressed in the same cells in an inducible manner, catalase showed a time-dependent response with no acute benefit, but a chronic benefit due to altered remodeling. In myeloid cells, catalase over-expression reduced angiogenesis during hindlimb ischemia and prevented monocyte migration. In the present study, due to the large inflammatory response following infarction, we examined myeloid-specific catalase over-expression on post-infarct healing. We found a significant increase in catalase levels following infarction that led to a decrease in H₂O₂ levels, leading to improved acute function. This increase in function could be attributed to reduced infarct size and improved angiogenesis. Despite these initial improvements, there was no improvement in chronic function, likely due to increased fibrosis. These data combined with what has been previously shown underscore the need for temporal, cell-specific catalase delivery as a potential therapeutic option.

[A pathophysiological role of cytochrome p450 involved in production of reactive oxygen species]

Dysregulation of the production of reactive oxygen species (ROS) determines cellular function. Cytochrome P450s (CYPs) regulates ROS production and contributes to the process of cell death. This review summarizes our recent findings, focusing on the involvement of CYPs in pathophysiology induced by ROS. 1. Quinone toxicity in hepatocytes: CYPs require electrons supplied from NADPH-cytochrome P450 reductase (NPR) during the process of metabolism. NPR also provides electrons to quinone compounds, which compete with CYPs over electrons. Inhibition of CYPs shifts NPR's electron flow more to quinones, which accelerates the redox cycle to enhance ROS production and quinone toxicity. 2. Myocardial ischemia-reperfusion injury: Reperfusion of blood flow after coronary artery occlusion induces cell damage, as evident by the extension of myocardial infarct size and caspase-independent cell apoptosis. CYP2C6 appears to be a source for ROS production, since sulfaphenazole, a selective inhibitor of CYP2C6, reduces this damage. ROS produced by CYP2C6 during the reperfusion causes translational activation of Noxa and BimEL, as well as the suppression of caspase activation, resulting in caspase-independent apoptosis. 3. Primary hepatocyte apoptosis: Inhibition of catalase and glutathione peroxidase increases intracellular ROS and elicits caspase-independent hepatocyte apoptosis. SKF-525A, a pan-CYP inhibitor, suppresses these ROS increases and hepatocyte apoptosis. Increased ROS activates ERK and AP-1 by inhibition of tyrosine phosphatase, and inhibits BimEL degradation by proteasome. These results in the accumulation of mitochondrial BimEL, which then induces the release of cytochrome c and endonuclease G (EndoG). Increased ROS also keeps caspases inactivated. As a result, EndoG executes nucleosomal DNA fragmentation.

The effects of dietary restriction on oxidative stress in rodents

Oxidative stress is observed during aging and in numerous age-related diseases. Dietary restriction (DR) is a regimen that protects against disease and extends life span in multiple species. However, it is unknown how DR mediates its protective effects. One prominent and consistent effect of DR in a number of systems is the ability to reduce oxidative stress and damage. The purpose of this review is to comprehensively examine the hypothesis that dietary restriction reduces oxidative stress in rodents by decreasing reactive oxygen species (ROS) production and increasing antioxidant enzyme activity, leading to an overall reduction of oxidative damage to macromolecules. The literature reveals that the effects of DR on oxidative stress are complex and likely influenced by a variety of factors, including sex, species, tissue examined, types of ROS and antioxidant enzymes examined, and duration of DR. Here we present a comprehensive review of the existing literature on the effect of DR on mitochondrial ROS generation, antioxidant enzymes, and oxidative damage. In a majority of studies, dietary restriction had little effect on mitochondrial ROS production or antioxidant activity. On the other hand, DR decreased oxidative damage in the majority of cases. Although the effects of DR on endogenous antioxidants are mixed, we find that glutathione levels are the most likely antioxidant to be increased by dietary restriction, which supports the emerging redox-stress hypothesis of aging.

The efficacy of edaravone (radicut), a free radical scavenger, for cardiovascular disease

Edaravone was originally developed as a potent free radical scavenger, and has been widely used to treat acute ischemic stroke in Japan since 2001. Free radicals play an important role in the pathogenesis of a variety of diseases, such as cardiovascular diseases and stroke. Therefore, free radicals may be targets for therapeutic intervention in these diseases. Edaravone shows protective effects on ischemic insults and inflammation in the heart, vessel, and brain in experimental studies. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic, and anti-cytokine effects in cardiovascular diseases and stroke. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, heart failure, diabetes, or hypertension, because these diseases result from oxidative stress and/or cytokine-induced apoptosis. This review evaluates the potential of edaravone for treatment of cardiovascular disease, and covers clinical and experimental studies conducted between 1984 and 2013. We propose that edaravone, which scavenges free radicals, may offer a novel option for treatment of cardiovascular diseases. However, additional clinical studies are necessary to verify the efficacy of edaravone.

Synthesis, cytotoxicity, DNA binding and apoptosis of rhein-phosphonate derivatives as antitumor agents

Several rhein-phosphonate derivatives (5a-c) were synthesized and evaluated for in vitro cytotoxicity against HepG-2, CNE, Spca-2, Hela and Hct-116 cell lines. Some compounds showed relatively high cytotoxicity. Especially compounds 5b exhibited the strongest cytotoxicity against HepG-2 and Spca-2 cells (IC50 was 8.82 and 9.01 µM), respectively. All the synthesized compounds exhibited low cytotoxicity against HUVEC cells. Further experiments proved that 5b could disturb the cell cycle in HepG-2 cells and induce apoptosis. In addition, the binding properties of a model conjugate 5b to DNA were investigated by methods (UV-Vis, fluorescence, CD spectroscopy). Results indicated that 5b showed moderate ability to interact ct-DNA.

ROS-mediated PARP activity undermines mitochondrial function after permeability transition pore opening during myocardial ischemia-reperfusion

Background

Ischemia–reperfusion (I/R) studies have implicated oxidant stress, the mitochondrial permeability transition pore (mPTP), and poly(ADP‐ribose) polymerase (PARP) as contributing factors in myocardial cell death. However, the interdependence of these factors in the intact, blood‐perfused heart is not known. We therefore wanted to determine whether oxidant stress, mPTP opening, and PARP activity contribute to the same death pathway after myocardial I/R.

Methods and Results

A murine left anterior descending coronary artery (LAD) occlusion (30 minutes) and release (1 to 4 hours) model was employed. Experimental groups included controls and antioxidant‐treated, mPTP‐inhibited, or PARP‐inhibited hearts. Antioxidant treatment prevented oxidative damage, mPTP opening, ATP depletion, and PARP activity, placing oxidant stress as the proximal death trigger. Genetic deletion of cyclophilin D (CypD^−/−) prevented loss of total NAD⁺ and PARP activity, and mPTP‐mediated loss of mitochondrial function. Control hearts showed progressive mitochondrial depolarization and loss of ATP from 1.5 to 4 hours of reperfusion, but not outer mitochondrial membrane rupture. Neither genetic deletion of PARP‐1 nor its pharmacological inhibition prevented the initial mPTP‐mediated depolarization or loss of ATP, but PARP ablation did allow mitochondrial recovery by 4 hours of reperfusion.

Conclusions

These results indicate that oxidant stress, the mPTP, and PARP activity contribute to a single death pathway after I/R in the heart. PARP activation undermines cell survival by preventing mitochondrial recovery after mPTP opening early in reperfusion. This suggests that PARP‐mediated prolongation of mitochondrial depolarization contributes significantly to cell death via an energetic crisis rather than by mitochondrial outer membrane rupture.

Current progress in Reactive Oxygen Species (ROS)-Responsive materials for biomedical applications

Recently, significant progress has been made in developing “stimuli-sensitive” biomaterials as a new therapeutic approach to interact with dynamic physiological conditions. Reactive oxygen species (ROS) production has been implicated in important pathophysiological events, such as atherosclerosis,aging, and cancer. ROS are often overproduced locally in diseased cells and tissues, and they individually and synchronously contribute to many of the abnormalities associated with local pathogenesis. Therefore, the advantages of developing ROS-responsive materials extend beyond site-specific targeting of therapeutic delivery, and potentially include navigating,sensing, and repairing the cellular damages via programmed changes in material properties. Here we review the mechanism and development of biomaterials with ROS-induced solubility switch or degradation, as well as their performance and potential for future biomedical applications.

Cardiomyocyte-restricted overexpression of extracellular superoxide dismutase increases nitric oxide bioavailability and reduces infarct size after ischemia/reperfusion

Increased levels of extracellular superoxide dismutase (ecSOD) induced by preconditioning or gene therapy protect the heart from ischemia/reperfusion injury. To elucidate the mechanism responsible for this action, we studied the effects of increased superoxide scavenging on nitric oxide (NO) bioavailability in a cardiac myocyte-specific ecSOD transgenic (Tg) mouse. Results indicated that ecSOD overexpression increased cardiac myocyte-specific ecSOD activity 27.5-fold. Transgenic ecSOD was localized to the sarcolemma and, notably, the cytoplasm of cardiac myocytes. Ischemia/reperfusion injury was attenuated in ecSOD Tg hearts, in which infarct size was decreased and LV functional recovery was improved. Using the ROS spin trap, DMPO, electron paramagnetic resonance (EPR) spectroscopy demonstrated a significant decrease in ROS in Tg hearts during the first 20 min of reperfusion. This decrease in ROS was accompanied by an increase in NO production determined by EPR using the NO spin trap, Fe-MGD. Attenuated ROS in ecSOD Tg myocytes was also supported by decreased production of peroxynitrite (ONOO⁻). Increased NO bioavailability was confirmed by attenuated guanylate cyclase-dependent (p-VASP) signaling. In conclusion, attenuation of ROS levels by cardiac-specific ecSOD overexpression increases NO bioavailability in response to ischemia/reperfusion and protects against reperfusion injury. These findings are the first to demonstrate increased NO bioavailability with attenuation of ROS by direct measurement of these reactive species (EPR, reactive fluorescent dyes) with cardiac-specific ecSOD expression. This is also the first indication that the predominantly extracellular SOD isoform is capable of cytosolic localization that affects myocardial intracellular signal transduction and function.

Antioxidants for chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for premature cardiovascular disease and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor for some cardiovascular diseases. Antioxidant therapy may reduce cardiovascular mortality and morbidity in people with CKD.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on mortality and cardiovascular events in people with CKD stages 3 to 5; dialysis, and kidney transplantation patients.

SEARCH METHODS

We searched the Cochrane Renal Group's specialised register (July 2011), CENTRAL (Issue 6, 2011), MEDLINE (from 1966) and EMBASE (from 1980).

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) investigating the use of antioxidants for people with CKD, or subsets of RCTs reporting outcomes for participants with CKD.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using the random effects model and expressed as either risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We identified 10 studies (1979 participants) that assessed antioxidant therapy in haemodialysis patients (two studies); kidney transplant recipients (four studies); dialysis and non-dialysis CKD patients (one study); and patients requiring surgery (one study). Two additional studies reported the effect of an oral antioxidant inflammation modulator in patients with CKD (estimated glomerular filtration rate (eGFR) 20 to 45 mL/min/1.73 m²), and post-hoc findings from a subgroup of people with mild-to-moderate renal insufficiency (serum creatinine ≥125 μmol/L) respectively. Interventions included different doses of vitamin E (two studies); multiple antioxidant therapy (three studies); co-enzyme Q (one study); acetylcysteine (one study); bardoxolone methyl (one study); and human recombinant superoxide dismutase (two studies).Compared with placebo, antioxidant therapy showed no clear overall effect on cardiovascular mortality (RR 0.95, 95% CI 0.70 to 1.27; P = 0.71); all-cause mortality (RR 0.93, 95% CI 0.76 to 1.14; P = 0.48); cardiovascular disease (RR 0.78, 95% CI 0.52 to 1.18; P = 0.24); coronary heart disease (RR 0.71, 95% CI 0.42 to 1.23; P = 0.22); cerebrovascular disease (RR 0.91, 95% CI 0.63 to 1.32; P = 0.63); or peripheral vascular disease (RR 0.54, 95% CI 0.26 to 1.12; P = 0.10). Subgroup analyses found no evidence of significant heterogeneity based on proportions of males (P = 0.99) or diabetes (P = 0.87) for cardiovascular disease. There was significant heterogeneity for cardiovascular disease when studies were analysed by CKD stage (P = 0.003). Significant benefit was conferred by antioxidant therapy for cardiovascular disease prevention in dialysis patients (RR 0.57, 95% CI 0.41 to 0.80; P = 0.001), although no effect was observed in CKD patients (RR 1.06, 95% CI 0.84 to 1.32; P = 0.63).Antioxidant therapy was found to significantly reduce development of end-stage of kidney disease (ESKD) (RR 0.50, 95% CI 0.25 to 1.00; P = 0.05); lowered serum creatinine levels (MD 1.10 mg/dL, 95% CI 0.39 to 1.81; P = 0.003); and improved creatinine clearance (MD 14.53 mL/min, 95% CI 1.20 to 27.86; P = 0.03). Serious adverse events were not significantly increased by antioxidants (RR 2.26, 95% CI 0.74 to 6.95; P = 0.15).Risk of bias was assessed for all studies. Studies that were classified as unclear for random sequence generation or allocation concealment reported significant benefits from antioxidant therapy (RR 0.57, 95% CI 0.41 to 0.80; P = 0.001) compared with studies at low risk of bias (RR 1.06, 95% CI 0.84 to 1.32; P = 0.63).

AUTHORS' CONCLUSIONS

Although antioxidant therapy does not reduce the risk of cardiovascular and all-cause death or major cardiovascular events in people with CKD, it is possible that some benefit may be present, particularly in those on dialysis. However, the small size and generally suboptimal quality of the included studies highlighted the need for sufficiently powered studies to confirm this possibility. Current evidence suggests that antioxidant therapy in predialysis CKD patients may prevent progression to ESKD; this finding was however based on a very small number of events. Further studies with longer follow-up are needed for confirmation. Appropriately powered studies are needed to reliably assess the effects of antioxidant therapy in people with CKD.

Uncoupled eNOS annihilates neuregulin-1β-induced cardioprotection: a novel mechanism in pharmacological postconditioning in myocardial infarction

Myocardial infarct size can be limited by pharmacological postconditioning (pPC) with cardioprotective agents. Cardioprotective effects of neuregulin-1β (NRG) via activation of protein kinase B (Akt) and downstream pathways like endothelial nitric oxide synthase (eNOS) have been postulated based on results from cell culture experiments. The purpose of this study was to investigate if eNOS may be involved in pPC with NRG. NRG application in an ex vivo mouse model (C57Bl6) of ischemia-reperfusion injury was analyzed. Unexpectedly, the infarct size increased when NRG was infused starting 5 min prior to reperfusion, even though protective Akt and GSK3β phosphorylation were enhanced. In eNOS deficient mice, however, NRG significantly reduced the infarct size. Co-infusion of NRG and L-arginine (Arg) lead to a reduction in infarct size in wild type animals. Electron paramagnetic resonance measurements revealed that NRG treatment prior to reperfusion leads to an enhanced release of reactive oxygen species compared to controls and this effect is blunted by co-infusion of Arg. This study documents the cardioprotective mechanisms of NRG signaling to be mediated by GSK3β inactivation. This is the first study to show that this protection fails in situations with dysfunctional eNOS. In eNOS deficient mice NRG exerts its protective effect via the GSK3β pathway, suggesting that the eNOS can limit cardioprotection. As dysfunctional eNOS has been described in cardiovascular risk factors like diabetes, hypertension, and hypercholesterolemia these findings can help to explain lack of postconditioning performance in models of cardiovascular co-morbidities.

Inverse Association between Cardiac Troponin-I and Soluble Receptor for Advanced Glycation End Products in Patients with Non-ST-Segment Elevation Myocardial Infarction

Interaction of advanced glycation end products (AGEs) with the receptor for advanced AGEs (RAGE) results in activation of nuclear factor kappa-B, release of cytokines, expression of adhesion molecules, and induction of oxidative stress. Oxygen radicals are involved in plaque rupture contributing to thromboembolism, resulting in acute coronary syndrome (ACS). Thromboembolism and the direct effect of oxygen radicals on myocardial cells cause cardiac damage that results in the release of cardiac troponin-I (cTnI) and other biochemical markers. The soluble RAGE (sRAGE) compete with RAGE for binding with AGE, thus functioning as a decoy and exerting a cytoprotective effect. Low levels of serum sRAGE would allow unopposed serum AGE availability for binding with RAGE, resulting in the generation of oxygen radicals and proinflammatory molecules that have deleterious consequences and promote myocardial damage. sRAGE may stabilize atherosclerotic plaques. It is hypothesized that low levels of sRAGE are associated with high levels of serum cTnI in patients with ACS. The main objective of the study was to determine whether low levels of serum sRAGE are associated with high levels of serum cTnI in ACS patients. The serum levels of sRAGE and cTnI were measured in 36 patients with non-ST-segment elevation myocardial infarction (NSTEMI) and 30 control subjects. Serum levels of sRAGE were lower in NSTEMI patients (802.56 ± 39.32 pg/mL) as compared with control subjects (1311.43 ± 66.92 pg/mL). The levels of cTnI were higher in NSTEMI patients (2.18 ± 0.33 μg/mL) as compared with control subjects (0.012 ± 0.001 μg/mL). Serum sRAGE levels were negatively correlated with the levels of cTnI. In conclusion, the data suggest that low levels of serum sRAGE are associated with high serum levels of cTnI and that there is a negative correlation between sRAGE and cTnI.

Cardiac fibroblast death by ischemia/reperfusion is partially inhibited by IGF-1 through both PI3K/Akt and MEK-ERK pathways

Cardiac fibroblast (CF) death by ischemia/reperfusion (I/R) has major implications for cardiac wound healing. Although IGF-1 has well-known cytoprotective effects, no study has been done on CF subjected to simulated I/R. Simulated ischemia of neonate rat CF was performed in a free oxygen chamber in an ischemic medium; reperfusion was done in normal culture conditions. Cell viability was evaluated by trypan blue assay, and apoptosis by a FACS flow cytometer; p-ERK-1/2 and p-Akt levels were determined by western blot. We showed that simulated I/R triggers CF death by necrosis and apoptosis. IGF-1 partially inhibits I/R-induced apoptosis. PD98059 and LY294002 neutralize the preventive effects of IGF-1.

CONCLUSION

IGF-1 partially inhibits CF apoptosis induced by simulated I/R by PI3K/Akt- and MEK/ERK1/2-dependent signaling pathways.

Nitroso-redox balance in control of coronary vasomotor tone

Reactive oxygen species (ROS) are essential in vascular homeostasis but may contribute to vascular dysfunction when excessively produced. Superoxide anion (O(2)(·-)) can directly affect vascular tone by reacting with K(+) channels and indirectly by reacting with nitric oxide (NO), thereby scavenging NO and causing nitroso-redox imbalance. After myocardial infarction (MI), oxidative stress increases, favoring the imbalance and resulting in coronary vasoconstriction. Consequently, we hypothesized that ROS scavenging results in coronary vasodilation, particularly after MI, and is enhanced after inhibition of NO production. Chronically instrumented swine were studied at rest and during exercise before and after scavenging of ROS with N-(2-mercaptoproprionyl)-glycine (MPG, 20 mg/kg iv) in the presence or absence of prior inhibition of endothelial NO synthase (eNOS) with N(ω)-nitro-L-arginine (L-NNA, 20 mg/kg iv). In normal swine, MPG resulted in coronary vasodilation as evidenced by an increased coronary venous O(2) tension, and trends toward increased coronary venous O(2) saturation and decreased myocardial O(2) extraction. These effects were not altered by prior inhibition of eNOS. In MI swine, MPG showed a significant vasodilator effect, which surprisingly was abolished by prior inhibition of eNOS. Moreover, eNOS dimer/monomer ratio was decreased after MI, reflecting eNOS uncoupling. In conclusion, ROS exert a small coronary vasoconstrictor influence in normal swine, which does not involve scavenging of NO. This vasoconstrictor influence of ROS is slightly enhanced after MI. Since inhibition of eNOS abolished rather than augmented the vasoconstrictor influence of ROS in swine with MI, while eNOS dimer/monomer ratio was decreased, our data imply that uncoupled eNOS may be a significant source of O(2)(·-) after MI.

Scavenging ROS: superoxide dismutase/catalase mimetics by the use of an oxidation-sensitive nanocarrier/enzyme conjugate

Reactive Oxygen Species (ROS) are quintessential inflammatory compounds with oxidizing behavior. We have successfully developed a micellar system with responsiveness at the same time to two of the most important ROS: superoxide and hydrogen peroxide. This allows for an effective and selective capture of the two compounds and, in perspective, for inflammation-responsive drug release. The system is composed of superoxide dismutase (SOD) conjugated to oxidation-sensitive amphiphilic polysulfide/PEG block copolymers; the conjugate combines the SOD reactivity toward superoxide with that of hydrophobic thioethers toward hydrogen peroxide. Specifically, here we have demonstrated how this hybrid system can efficiently convert superoxide into hydrogen peroxide, which is then "mopped-up" by the polysulfides: this modus operandi is functionally analogous to the SOD/catalase combination, with the advantages of (a) being based on a single and more stable system, and (b) a higher overall efficiency due the physical proximity of the two ROS-reactive centers (SOD and polysulfides).