Antioxidant vitamins prevent cardiomyocyte apoptosis produced by norepinephrine infusion in ferrets

FRBM Mini REVIEW: Chemogenetic approaches to probe redox dysregulation in heart failure

Chemogenetics refers to experimental methods that use novel recombinant proteins that can be dynamically and uniquely regulated by specific biochemicals. Chemogenetic approaches allow the precise manipulation of cellular signaling to delineate the molecular pathways involved in both physiological and pathological disease states. Approaches utilizing yeast d-amino acid oxidase (DAAO) enable manipulation of intracellular redox metabolism through generation of hydrogen peroxide in the presence of d-amino acids and have led to the development of new and informative animal models to characterize the impact of oxidative stress in heart failure and neurodegeneration. These chemogenetic models, in which DAAO expression is regulated by different tissue-specific promoters, have led to a range of cardiac phenotypes. This review discusses chemogenetic approaches to manipulate oxidative stress in models of heart failure. These approaches provide new insights into the relationships between redox metabolism and normal and pathologic states in the heart, as well as in other diseases characterized by oxidative stress.

Chemogenetic Approaches to Probe Redox Pathways: Implications for Cardiovascular Pharmacology and Toxicology

Chemogenetics refers to experimental systems that dynamically regulate the activity of a recombinant protein by providing or withholding the protein's specific biochemical stimulus. Chemogenetic tools permit precise dynamic control of specific signaling molecules to delineate the roles of those molecules in physiology and disease. Yeast d-amino acid oxidase (DAAO) enables chemogenetic manipulation of intracellular redox balance by generating hydrogen peroxide only in the presence of d-amino acids. Advances in biosensors have allowed the precise quantitation of these signaling molecules. The combination of chemogenetic approaches with biosensor methodologies has opened up new lines of investigation, allowing the analysis of intracellular redox pathways that modulate physiological and pathological cell responses. We anticipate that newly developed transgenic chemogenetic models will permit dynamic modulation of cellularredox balance in diverse cells and tissues and will facilitate the identification and validation of novel therapeutic targets involved in both physiological redox pathways and pathological oxidative stress.

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Coordinate and redox interactions of epinephrine (Epi) with iron at physiological pH are essential for understanding two very different phenomena – the detrimental effects of chronic stress on the cardiovascular system and the cross-linking of catecholamine-rich biopolymers and frameworks. Here we show that Epi and Fe³⁺ form stable high-spin complexes in the 1:1 or 3:1 stoichiometry, depending on the Epi/Fe³⁺ concentration ratio (low or high). Oxygen atoms on the catechol ring represent the sites of coordinate bond formation within physiologically relevant bidentate 1:1 complex. Redox properties of Epi are slightly impacted by Fe³⁺. On the other hand, Epi and Fe²⁺ form a complex that acts as a strong reducing agent, which leads to the production of hydrogen peroxide via O₂ reduction, and to a facilitated formation of the Epi–Fe³⁺ complexes. Epi is not oxidized in this process, i.e. Fe²⁺ is not an electron shuttle, but the electron donor. Epi-catalyzed oxidation of Fe²⁺ represents a plausible chemical basis of stress-related damage to heart cells. In addition, our results support the previous findings on the interactions of catecholamine moieties in polymers with iron and provide a novel strategy for improving the efficiency of cross-linking.

Blueberry polyphenols prevent cardiomyocyte death by preventing calpain activation and oxidative stress

The purpose of this study was to examine the efficacy of an aqueous wild blueberry extract and five wild blueberry polyphenol fractions on an in vitro model of heart disease. Adult rat cardiomyocytes were pretreated with extract and fractions, and then exposed to norepinephrine (NE). Cardiomyocyte hypertrophy, cell death, oxidative stress, apoptosis and cardiomyocyte contractile function as well as the activities of calpain, superoxide dismutase (SOD) and catalase (CAT) were measured in cardiomyocytes treated with and without NE and blueberry fraction (BF). Four of five blueberry fractions prevented cell death and cardiomyocyte hypertrophy induced by NE. Total phenolic fraction was used for all further analysis. The NE-induced increase in oxidative stress, nuclear condensation, calpain activity and lowering of SOD and CAT activities were prevented upon pretreatment with BF. Reduced contractile function was also significantly improved with BF pretreatment. Blueberry polyphenols prevent NE-induced adult cardiomyocyte hypertrophy and cell death. The protective effects of BF may be in part attributed to a reduction in calpain activity and oxidative stress.

Nongenomic effects of estrogen mediate the dose-related myocardial oxidative stress and dysfunction caused by acute ethanol in female rats

Acute ethanol lowers blood pressure (BP) and cardiac output in proestrus and after chronic estrogen (E2) replacement in ovariectomized (OVX) female rats. However, whether rapid nongenomic effects of estrogen mediate these hemodynamic effects of ethanol remains unanswered. To test this hypothesis, we investigated the effect of ethanol (0.5 or 1.5 g/kg iv) on left ventricular (LV) function and oxidative markers in OVX rats pretreated 30 min earlier with 1 μg/kg E2 (OVXE2) or vehicle (OVX) and in proestrus sham-operated (SO) rats. In SO rats, ethanol caused significant and dose-related reductions in BP, rate of rise in LV pressure (LV dP/dtmax), and LV developed pressure (LVDP). These effects of ethanol disappeared in OVX rats and were restored in OVXE2 rats, suggesting rapid estrogen receptor signaling mediates the detrimental effects of ethanol on LV function. Ex vivo studies revealed that the estrogen-dependent myocardial dysfunction caused by ethanol was coupled with higher LV 1) generation of reactive oxygen species (ROS), 2) expression of malondialdehyde and 4-hydroxynonenal protein adducts, 3) phosphorylation of protein kinase B (Akt) and extracellular signal-regulated kinases (ERK1/2), and 4) catalase activity. ERK1/2 inhibition by PD-98059 (1 mg/kg iv) abrogated the myocardial dysfunction, hypotension, and the elevation in myocardial ROS generation caused by ethanol. We conclude that rapid estrogen receptor signaling is implicated in cellular events that lead to the generation of aldehyde protein adducts and Akt/ERK1/2 phosphorylation, which ultimately mediate the estrogen-dependent LV oxidative stress and dysfunction caused by ethanol in female rats.

Vitamin C for preventing and treating tetanus

BACKGROUND

Tetanus is a severe disease that can be prevented by vaccination. In developing countries vaccination coverage is not always high. Cases still occur also in developed countries, particularly in elderly people owing to their reduced immuno protection. There are about 1 million tetanus cases per year globally. In animal studies, vitamin C has protected against various infections and bacterial toxins. In a study with rats, vitamin C protected against the purified tetanus toxin.

OBJECTIVES

To assess the prophylactic and therapeutic effect of vitamin C on tetanus.

SEARCH METHODS

In May 2013 we searched the Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations ); and Ovid EMBASE for this third update.

SELECTION CRITERIA

Controlled trials of vitamin C as a prevention or treatment for tetanus, whether or not these were placebo controlled, in any language, published or unpublished. Two review authors independently made inclusion decisions.

DATA COLLECTION AND ANALYSIS

Both review authors independently extracted data from trial reports and assessed methodological quality. Since one of the cells in a 2 × 2 table had no events, we calculated the odds ratio (OR) and its 95% confidence interval (CI) for case fatality rate by using the Peto-method. Another of the 2 × 2 tables had no empty cells and the inverse-variance method was used to calculate its risk ratio (RR) estimate and 95% CI. We also used the Fisher's exact test to calculate the exact 95% CI for the OR of the 2 × 2 table with the empty cell.

MAIN RESULTS

One single trial was eligible for inclusion. This non-randomised, unblinded, controlled trial undertaken in Bangladesh involved 117 tetanus patients. Vitamin C at a dosage of 1 g/day was administered intravenously alongside conventional treatment. At recruitment, the participants were stratified into two age groups and the results were reported by age. There was a significant difference in the vitamin C effect between the two age groups (P = 0.01). In the tetanus patients aged 1 to 12 years (n = 62), vitamin C treatment was associated with a 100% reduction in case fatality rate (95% CI from -100% to -94%). In patients aged 13 to 30 years (n = 55), vitamin C treatment was associated with a 45% reduction in case fatality rate (95% CI from -69% to -5%).

AUTHORS' CONCLUSIONS

A single, non-randomised, poorly reported trial of vitamin C as a treatment for tetanus suggests a considerable reduction in mortality. However, concerns about trial quality mean that this result must be interpreted with caution and vitamin C cannot be recommended as a treatment for tetanus on the basis of this evidence. New trials should be carried out to examine the effect of vitamin C on tetanus treatment.

Diabetic cardiomyopathy: pathophysiological mechanisms and cardiac dysfuntion

Several experimental, pathological, epidemiological, and clinical studies have clearly depicted that diabetes mellitus results in cardiac functional and structural changes. Diabetic cardiomyopathy results in both structural and functional alterations in the myocardium. Several mechanisms have been implicated in the pathophysiology of diabetic cardiomyopathy. Of these, metabolic disturbances, myocardial fibrosis, small vessel disease, and cardiac autonomic neuropathy are the major players in the pathophysiology of diabetic cardiomyopathy. This review is intended to discuss various such pathophysiological mechanisms of diabetic cardiomyopathy. We have also described the systolic and diastolic dysfunctioning and its corelation to structural changes in diabetes.

Carvedilol: a third-generation β-blocker should be a first-choice β-blocker

β-Blockers are a standard of care in many clinical settings such as acute myocardial infarction, heart failure and patients at risk for a coronary event. However, not all β-blockers are the same and they vary in properties such as lipophilicity, metabolic profile, receptor inhibition, hemodynamics, tolerability and antioxidant/anti-inflammatory effects. It has been unclear whether these differences affect outcomes or if one β-blocker should be preferred over another. This review will summarize the properties of metoprolol, atenolol and carvedilol, as well as comparative experimental and clinical trials between these agents. We will provide compelling evidence of why carvedilol should be a first-line β-blocker and why it offers many advantages over the β1-selective β-blockers.

Antioxidant activities of aqueous leaf extracts of Toona sinensis on free radical-induced endothelial cell damage

ETHNOPHARMACOLOGICAL RELEVANCE

In Taiwan, Toona sinensis (Toona sinensis) is well known as a traditional Chinese medicine, while the underlying pharmacological mechanisms of this drug are still a matter of debate.

MATERIALS AND METHODS

The purpose of this study was to evaluate the protective effects of non-cytotoxic concentrations of aqueous leaf extracts of Toona sinensis (TS extracts; 50-100 μg/mL) and gallic acid (5 μg/mL), a major component of these extracts, against AAPH-induced oxidative cell damage in human umbilical vein endothelial cells (ECs).

RESULTS

Exposure of ECs to AAPH (15 mM) decreased cell viability from 100% to 43%. However, ECs were pre-incubated with TS extracts prior to AAPH induction resulted in increased resistance to oxidative stress and cell viability in a dose-dependent manner. An increase in ECs-derived PGI(2) and IL-1 β in response to AAPH exposure was positively correlated with cytotoxicity and negatively with TS extracts concentrations. In addition, gallic acid also suppressed PGI(2) and IL-1 β production in AAPH-induced ECs. Notably, TS extracts/gallic acid treatment significantly inhibited ROS generation, MDA formation, SOD/catalase activity, and Bax/Bcl-2 dysregulation in AAPH-stimulated ECs. Pretreatment of ECs with TS extracts/gallic acid also suppressed AAPH-induced cell surface expression and secretion of VCAM-1, ICAM-1 and E-selectin, which was associated with abridged adhesion of U937 leukocytes to ECs. Moreover, TS extracts/gallic acid treatment significantly inhibited the AAPH-mediated up regulation of PAI-1 and down regulation of t-PA in ECs, which may decrease fibrinolytic activity.

CONCLUSIONS

Therefore, Toona sinensis may possess antioxidant properties that protect endothelial cells from oxidative stress. Our results also support the traditional use of Toona sinensis in the treatment of free radical-related diseases and atherosclerosis.

Resveratrol prevents norepinephrine induced hypertrophy in adult rat cardiomyocytes, by activating NO-AMPK pathway

Increased adrenergic drive is a major factor influencing the development of pathological cardiac hypertrophy, a stage which precedes overt heart failure. We examined the effect of resveratrol, a polyphenol (found predominantly in grapes), in preventing norepinephrine induced hypertrophy of adult cardiomyocyte, and the role of nitric oxide (NO) and adenosine monophosphate kinase (AMPK) in the effects of resveratrol. Cardiomyocytes isolated from adult rats were pretreated, or not, with resveratrol and then exposed to norepinephrine for 24h. In other experiments cardiomyocytes were also treated with different pharmacological inhibitors of NO synthase, AMPK and sirtuin for elucidating the signaling pathways underlying the effect of resveratrol. In order to validate the role of these signaling molecules in the in vivo settings, we also examined hearts from resveratrol treated spontaneously hypertensive rats (SHR), a genetic model of essential hypertension. Cardiomyocyte hypertrophy was determined by morphometry and (3)H-phenylalanine incorporation assay. NO levels and AMPK activity were measured using a specific assay kit and western blot analysis respectively. In vitro, resveratrol prevented the norepinephrine-induced increase in cardiomyocytes size and protein synthesis. Pharmacological inhibition of NO-AMPK signaling abolished the anti-hypertrophic action of resveratrol. Consistent with the in vitro findings, the anti-hypertrophic effect of resveratrol in the SHR model was associated with increases in NO and AMPK activity. This study demonstrates that NO-AMPK signaling is linked to the anti-hypertrophic effect of resveratrol in adult cardiomyocytes in vitro, and in the SHR model in vivo.

Tumor necrosis factor receptor 2 signaling limits β-adrenergic receptor-mediated cardiac hypertrophy in vivo

The in vivo role of TNF signaling in the genesis of β-adrenergic receptor (β-AR)-mediated cardiac hypertrophy is unknown. Wild-type (WT), TNF receptor 1 (TNFR1)-/- and TNFR2-/- mice were given isoproterenol (ISO, 12.5 μg/kg/h) or saline (SAL) for 1 or 7 days. In WT mice, 7 days of ISO yielded chamber/myocyte hypertrophy and hyperdynamic function without hypertension or fibrosis. WT ISO hearts exhibited an early (1 day) pro-inflammatory response with significant (p < 0.05) activation of nuclear factor (NF)-κB and activator protein 1 (AP-1) and upregulation of TNF, interleukin (IL)-1β and IL-6, inducible nitric oxide synthase (iNOS) and monocyte chemotactic protein-1 (MCP-1), together with increased anti-inflammatory IL-10. This response diminished markedly by 7 days. As compared with WT ISO mice, TNFR1-/- ISO mice exhibited significantly (p < 0.05) less NF-κB and AP-1 activation, less IL-1β, TNF, iNOS and MCP-1 upregulation, but greater IL-10 at 1 day. However, there were no differences in hypertrophy or contractility at 7 days. In contrast, TNFR2-/- ISO mice exhibited augmented NF-κB and AP-1 activation, increased IL-1β and diminished IL-10 expression at 1 day, and significant exaggeration of hypertrophy and less contractile augmentation at 7 days. Moreover, TNFR2-/- mice exposed to tenfold higher ISO doses displayed significant mortality. TNF signaling contributes to β-AR-mediated cardiac remodeling in vivo in a receptor-specific manner. Unopposed TNFR1 activation is pro-inflammatory, pro-hypertrophic and promotes functional decline. However, co-activation of TNFR2 during β-AR stress is anti-inflammatory and counterbalances these deleterious effects. TNF modulatory strategies that maintain TNFR2 signaling may help prevent the detrimental long-term effects of β-AR stimulation in the heart.

Ethanol influences on Bax translocation, mitochondrial membrane potential, and reactive oxygen species generation are modulated by vitamin E and brain-derived neurotrophic factor

BACKGROUND

This study investigated ethanol influences on intracellular events that predispose developing neurons toward apoptosis and the capacity of the antioxidant α-tocopherol (vitamin E) and the neurotrophin brain-derived neurotrophic factor (BDNF) to modulate these effects. Assessments were made of the following: (i) ethanol-induced translocation of the pro-apoptotic Bax protein to the mitochondrial membrane, a key upstream event in the initiation of apoptotic cell death; (ii) disruption of the mitochondrial membrane potential (MMP) as a result of ethanol exposure, an important process in triggering the apoptotic cascade; and (iii) generation of damaging reactive oxygen species (ROS) as a function of ethanol exposure.

METHODS

These interactions were investigated in cultured postnatal day 8 neonatal rat cerebellar granule cells, a population vulnerable to developmental ethanol exposure in vivo and in vitro. Bax mitochondrial translocation was analyzed via subcellular fractionation followed by Western blot, and mitochondrial membrane integrity was determined using the lipophilic dye, JC-1, that exhibits potential-dependent accumulation in the mitochondrial membrane as a function of the MMP.

RESULTS

Brief ethanol exposure in these preparations precipitated Bax translocation, but both vitamin E and BDNF reduced this effect to control levels. Ethanol treatment also resulted in a disturbance of the MMP, and this effect was blunted by the antioxidant and the neurotrophin. ROS generation was enhanced by a short ethanol exposure in these cells, but the production of these harmful free radicals was diminished to control levels by cotreatment with either vitamin E or BDNF.

CONCLUSIONS

These results indicate that both antioxidants and neurotrophic factors have the potential to ameliorate ethanol neurotoxicity and suggest possible interventions that could be implemented in preventing or lessening the severity of the damaging effects of ethanol in the developing central nervous system seen in the fetal alcohol syndrome (FAS).

Cardiac β1-adrenoceptor expression in two stress-induced cardiomyopathy-related deaths

Stress-induced cardiomyopathy (SICM) is characterized by transient systolic dysfunction of the apical and/or midventricular myocardial segments in the absence of obstructive coronary artery disease and is unique in that it can manifest itself after acute emotional stress. Excessive amounts of catecholamines released from sympathetic nerve endings as well as from the adrenal medulla under stressful conditions are considered to produce intracellular Ca(2+) overload and cardiac dysfunction through the β(1)-adrenoceptor signal transduction pathway. We describe the clinical and pathomorphological findings in two stress-induced cardiomyopathy fatal cases. Levels of catecholamines and their metabolites in urine samples were assessed too. Morphological patterns seen in SICM result from the complex interplay between sympathetic innervations, β-receptor density and function and catecholamine sensitivity.

Carvedilol treatment ameliorates acute coxsackievirus B3-induced myocarditis associated with oxidative stress reduction

Oxidative stress has been implicated in the pathogenesis of acute myocarditis. The imbalance between the occurrence of reactive oxygen species and the cellular antioxidant defense mechanism plays a key role in myocardial injury of viral myocarditis. Carvedilol, a nonselective beta-adrenoceptor antagonist with additional alpha1-adrenergic blocking and antioxidant properties, has been shown to be cardioprotective in experimental myocarditis. However, the expression of 4-hydroxy-2-nonenal (4-HNE), the most reliable marker of lipid peroxidation, has not been studied, and the antioxidative effects of carvedilol have not been investigated in the setting of acute viral myocarditis. This study was therefore designed to determine whether levels of lipid peroxides are elevated in the myocardium and whether carvedilol reduces the lipid peroxidation level and increases antioxidant enzyme activities. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of carvedilol and metoprolol on 14-day survival rate, myocardial histopathological changes, cardiac function, the expression of 4-HNE, virus titers, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidases (GSH-Px) activities were studied. Lipid peroxidations including 4-HNE and MDA, were elevated in murine coxsackievirus-induced acute viral myocarditis. Carvedilol, but not metoprolol, improved survival, reduced lipid peroxidations including 4-HNE and MDA, and increased antioxidant enzyme activities including SOD and GSH-Px with amelioration of acute viral myocarditis. These results show that carvedilol but not metoprolol exerts some of its beneficial effects by inhibiting peroxidants.

Crocetin attenuates norepinephrine-induced cytotoxicity in primary cultured rat cardiac myocytes by antioxidant in vitro

This study aims to investigate the protective role of crocetin, a natural antioxidant, against cytotoxicity produced by exposure to norepinephrine (NE) in primary cultured rat cardiac myocytes. Reactive oxygen species (ROS) and Ca(2+) in cells were evaluated by fluorescence microplate reader using 6-carboxy-2',7'-dichlorofluorescein and fluoro-3-acetoxymethyl ester, respectively. Lipid peroxidation was quantified using thiobarbituric acid-reactive substances. The activities of superoxide dismutase (SOD) and contents of glutathione (GSH) were detected by xanthine/xanthime oxidase-mediated ferricytochrome c reduction assay, and recycling effection of glutathione disulfide with GSH reductase and NADPH, respectively. The apoptotic cells were assayed by fluorescein diacetate (FDA)-ethidium bromide (EB) two-staining method. Intracellular accumulation of ROS, Ca(2+), and products of lipid peroxidation resulting from NE were significantly reduced by crocetin. Preincubation of primary cultured rat cardiac myocytes with crocetin remarkably prevented the decrease in SOD activity and quantities of GSH induced by NE. The percentage of NE-induced apoptosis in the cells was decreased by FDA-EB two-staining assay after pretreated with crocetin. The results showed that crocetin may ameliorate NE-induced injury in cardiac myocytes by enhanced SOD activity and increased quantities of GSH, decreased lipid peroxidation and Ca(2+) in cells, and apoptosis death ratio that may represent the cellular mechanisms for its cardioprotective role.

Exercise training reduces sympathetic modulation on cardiovascular system and cardiac oxidative stress in spontaneously hypertensive rats

BACKGROUND

Spontaneously hypertensive rats (SHRs) show increased cardiac sympathetic activity, which could stimulate cardiomyocyte hypertrophy, cardiac damage, and apoptosis. Norepinephrine (NE)-induced cardiac oxidative stress seems to be involved in SHR cardiac hypertrophy development. Because exercise training (ET) decreases sympathetic activation and oxidative stress, it may alter cardiac hypertrophy in SHR. The aim of this study was to determine, in vivo, whether ET alters cardiac sympathetic modulation on cardiovascular system and whether a correlation exists between cardiac oxidative stress and hypertrophy.

METHODS

Male SHRs (15-weeks old) were divided into sedentary hypertensive (SHR, n = 7) and exercise-trained hypertensive rats (SHR-T, n = 7). Moderate ET was performed on a treadmill (5 days/week, 60 min, 10 weeks). After ET, cardiopulmonary reflex responses were assessed by bolus injections of 5-HT. Autoregressive spectral estimation was performed for systolic arterial pressure (SAP) with oscillatory components quantified as low (LF: 0.2-0.75 Hz) and high (HF: 0.75-4.0 Hz) frequency ranges. Cardiac NE concentration, lipid peroxidation, antioxidant enzymes activities, and total nitrates/nitrites were determined.

RESULTS

ET reduced mean arterial pressure, SAP variability (SAP var), LF of SAP, and cardiac hypertrophy and increased cardiopulmonary reflex responses. Cardiac lipid peroxidation was decreased in trained SHRs and positively correlated with NE concentrations (r = 0.89, P < 0.01) and heart weight/body weight ratio (r = 0.72, P < 0.01), and inversely correlated with total nitrates/nitrites (r = -0.79, P < 0.01). Moreover, in trained SHR, cardiac total nitrates/nitrites were inversely correlated with NE concentrations (r = -0.82, P < 0.01).

CONCLUSIONS

ET attenuates cardiac sympathetic modulation and cardiac hypertrophy, which were associated with reduced oxidative stress and increased nitric oxide (NO) bioavailability.

Desferrioxamine (DFX) induces apoptosis through the p38-caspase8-Bid-Bax pathway in PHA-stimulated human lymphocytes

Desferrioxamine (DFX) induces apoptosis in human lymphocytes, although the mechanism leading to cell death is unclear. Therefore, we investigated the signaling pathways implicated in DFX-induced apoptosis in lymphocytes. DFX treatment activated caspase-9, caspase-3, and caspase-8. DFX-induced apoptosis was inhibited by both z-IETD-fmk and z-DEVD-fmk. DFX treatment also enhanced caspase-8 activity, Bid cleavage, and the conformational activation of Bax. DFX treatment activated two MAPKs, p38 and JNK, and induced the phosphorylation of two proteins in the p38 pathway, MKK3 and MKK6. DFX treatment also increased the phosphorylation of two downstream targets of p38, ATF-2 and MAPKAPK2, indicating that DFX promotes p38 activity. In addition, the selective p38 inhibitor SB203580 suppressed DFX-induced apoptosis and caspase-8 activation, whereas the JNK inhibitor, SP600125, and the ERK inhibitor, PD98059, had no effect. Our results suggest that DFX-induced apoptosis is mediated by the p38 pathway and a caspase-8-dependent Bid-Bax pathway in human lymphocytes.

Norepinephrine treatment and aging lead to systemic and intracellular oxidative stress in rats

Reactive oxygen species (ROS) play important roles in cellular senescence and organismic aging. Furthermore, they have been implicated in some of the adverse effects of chronic stress due to elevated peripheral levels of catecholamines. Here, we applied three different techniques to individually compare the systemic and intracellular oxidative stress in aged (23 months) and young (5 months) Sprague-Dawley rats, and in young rats treated for 12 or 24 h with norepinephrine (NE). Thiol groups of blood serum proteins (RSH) were determined by means of Ellman's reaction. Intracellular ROS were assessed in spleen cells and peripheral blood lymphocytes (PBL) by carbonylation of cellular (spleen) proteins as determined by immunoblotting (Oxyblot) and/or by means of 2',7'-dichlorofluorescein (DCF) fluorescence. As compared to the young, untreated controls, both old rats and NE treated young rats showed similarly lowered RSH values paralleled by elevated intracellular ROS levels or enhanced Oxyblot signals. Individual RSH values were highly significantly, negatively correlated with respective Oxyblot data as well as with DCF fluorescence. The results confirm the roles of ROS in aging and adrenergic stress in the rat model, and suggest that the decrease in RSH of blood serum may be taken as a valid indicator for the enhanced oxidative stress in lymphocytes.

Norepinephrine induces apoptosis in neonatal rat endothelial cells via a ROS-dependent JNK activation pathway

Our previous study demonstrated that norepinephrine (NE) induces endothelial apoptosis mainly through down-regulation of Bcl-2 protein and activation of the beta-adrenergic and caspase-2 pathways. However, whether reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPKs) are involved in this signal transduction remains unknown. Endothelial cells cultured from neonatal rat heart were treated with 100 microM NE. Proteins of MAPKs and Bcl-2 family were assayed by Western blotting. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated nick end-labeling assay. ROS was analyzed with flow cytometry. Caspase activity was measured using specific fluorogenic substrates. Treatment with NE increased intracellular ROS level and extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 phosphorylation. Whereas the phosphorylated form of Akt was decreased. The NE-induced apoptosis was abrogated by SP600125 (a specific inhibitor of JNK). Antioxidants such as vitamin C and N-acetyl cysteine inhibited NE-induced ROS production, JNK phosphorylation, caspase activation and apoptosis. Exogenously added superoxide dismutase or catalase markedly diminished NE-induced ROS production and cell death. In conclusions, our study is the first report documenting that NE induces apoptosis in neonatal rat endothelial cells via a ROS-dependent JNK activation pathway. Antioxidants may be useful in the prevention and management of NE-mediated endothelial apoptosis during heart failure.

Correlation between cardiac oxidative stress and myocardial pathology due to acute and chronic norepinephrine administration in rats

Background: To investigate the cardiotoxic role of reactive oxygen species (ROS) and of products derived from catecholamines auto-oxidation, we studied: (1) the response of antioxidant cardiac cellular defence systems to oxidative stress induced by norepinephrine (NE) administration, (2) the effect of NE administration on cardiac β₁-adrenergic receptors by means of receptor binding assay, (3) the cellular morphological alterations related to the biologically cross-talk between the NE administration and cytokines [tumor necrosis factor-alpha (TNF-α), monocyte chemotactic protein-1 (MCP-1), interleukins IL6, IL8, IL10]Methods and Results: A total of 195 male rats was used in the experiment. All animals underwent electrocardiogram (EKG) before being sacrificed. The results obtained show that NE administration influences the antioxidant cellular defence system significantly increasing glutathione peroxidase (GPx) activity, glutathione reductase (GR) and superoxide dismutase (SOD). The oxidized glutathione (GSH/GSSG) ratio significantly decreases and malondialdehyde (MDA) levels increase showing a state of lipoperoxidation of cardiac tissue. We describe a significant apoptotic process randomly sparse in the damaged myocardium and the effect of ROS on the NE-mediated TNF-α, MCP-1, and IL6, IL8, IL10 production. Conclusions: Our results support the hypothesis that catecholamines may induce oxidative damage through reactive intermediates resulting from their auto-oxidation, irrespective of their interaction with adrenergic receptors, thus representing an important factor in the pathogenesis of catecholamines-induced cardiotoxicity. The rise of the cardioinhibitory cytokines may be interpreted as the adaptive response of jeopardized myocardium with respect to the cardiac dysfunction resulting from NE injection.

Calcium signaling phenomena in heart diseases: a perspective

Ca(2+) is a major intracellular messenger and nature has evolved multiple mechanisms to regulate free intracellular (Ca(2+))(i) level in situ. The Ca(2+) signal inducing contraction in cardiac muscle originates from two sources. Ca(2+) enters the cell through voltage dependent Ca(2+) channels. This Ca(2+) binds to and activates Ca(2+) release channels (ryanodine receptors) of the sarcoplasmic reticulum (SR) through a Ca(2+) induced Ca(2+) release (CICR) process. Entry of Ca(2+) with each contraction requires an equal amount of Ca(2+) extrusion within a single heartbeat to maintain Ca(2+) homeostasis and to ensure relaxation. Cardiac Ca(2+) extrusion mechanisms are mainly contributed by Na(+)/Ca(2+) exchanger and ATP dependent Ca(2+) pump (Ca(2+)-ATPase). These transport systems are important determinants of (Ca(2+))(i) level and cardiac contractility. Altered intracellular Ca(2+) handling importantly contributes to impaired contractility in heart failure. Chronic hyperactivity of the beta-adrenergic signaling pathway results in PKA-hyperphosphorylation of the cardiac RyR/intracellular Ca(2+) release channels. Numerous signaling molecules have been implicated in the development of hypertrophy and failure, including the beta-adrenergic receptor, protein kinase C, Gq, and the down stream effectors such as mitogen activated protein kinases pathways, and the Ca(2+) regulated phosphatase calcineurin. A number of signaling pathways have now been identified that may be key regulators of changes in myocardial structure and function in response to mutations in structural components of the cardiomyocytes. Myocardial structure and signal transduction are now merging into a common field of research that will lead to a more complete understanding of the molecular mechanisms that underlie heart diseases. Recent progress in molecular cardiology makes it possible to envision a new therapeutic approach to heart failure (HF), targeting key molecules involved in intracellular Ca(2+) handling such as RyR, SERCA2a, and PLN. Controlling these molecular functions by different agents have been found to be beneficial in some experimental conditions.

Micronutrients and their supplementation in chronic cardiac failure. An update beyond theoretical perspectives

Physicians' use of micronutrients to improve symptoms or outcomes in chronic illness has until recently been guided by limited data on the actions of individual agents in vitro or in animal studies. However several recently published clinical trials have provided information about which groups of patients are likely to benefit from which combination of micronutrients. Patients with chronic cardiac failure (CCF), particularly elderly individuals, have several reasons to be deficient in micronutrients including reduced intake, impaired gastrointestinal absorption and increased losses on the background of increased utilisation due for example to increased oxidative stress. Studies of nutritional supplementation in CCF patients have usually concentrated on specific agents. However given that many micronutrients have synergistic influences upon metabolic processes this strategy might merely lead to a shifting of a limiting step. Rather, a strategy of increasing the availability of multiple agents at once might be more logical. The aim of this article is to briefly review the experimental rationale for each of the micronutrients of potential benefit in chronic heart failure and examine the current clinical trial evidence supporting their use.

Elevated levels of oxidative DNA damage in serum and myocardium of patients with heart failure

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of chronic heart failure. The present study investigated whether the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were elevated in the serum and myocardium of patients with dilated cardiomyopathy (DCM), and furthermore whether carvedilol, a vasodilating beta-blocker with antioxidant activity, could reduce the levels.

METHODS AND RESULTS

Serum levels of 8-OHdG were measured by enzyme immunoassay in 56 patients with DCM and in 20 control subjects. DCM patients had significantly elevated serum levels of 8-OHdG compared with control subjects. Endomyocardial biopsy samples obtained from 12 DCM patients and 5 control subjects with normal cardiac function were studied immunohistochemically for the expression of 8-OHdG. Positive 8-OHdG staining was found in the nuclei of cardiomyocytes from DCM patients but not in those from control subjects. After treatment with carvedilol, the serum levels of 8-OHdG in DCM patients significantly decreased by 19%, together with amelioration of heart failure.

CONCLUSIONS

Levels of 8-OHdG are elevated in the serum and myocardium of patients with heart failure. Treatment with carvedilol might be effective for decreasing the oxidative DNA damage.

EUK-8, a superoxide dismutase and catalase mimetic, reduces cardiac oxidative stress and ameliorates pressure overload-induced heart failure in the harlequin mouse mutant

OBJECTIVES

The purpose of this study was to identify apoptosis-inducing factor (AIF) as a cardiac mitochondrial antioxidant and assess the efficacy of EUK-8, a salen-manganese catalytic free radical scavenger, to protect the AIF-deficient myocardium against pressure overload.

BACKGROUND

Oxidative stress has been postulated to provoke cell death and pathologic remodeling in heart failure. We recently characterized the apoptosis-inducing factor-deficient harlequin (Hq) mouse mutant to display excessive pressure overload-induced oxidative stress, cell death, accelerated progression to heart failure, and a reduced capacity of subsarcolemmal mitochondria to scavenge free radicals, suggesting a role for AIF as a novel mitochondrial antioxidant.

METHODS

Oxidative stress-sensitized Hq mutant mice and their wild-type (WT) counterparts were given low-dose EUK-8 (25 mg/kg/day), an antioxidant with superoxide dismutase, catalase, and oxyradical scavenging properties, or vehicle for 4 weeks, and subjected to pressure overload (transverse aortic constriction) for 4 weeks. Myocardial geometry and function was serially assessed by echocardiography.

RESULTS

EUK-8 ameliorated survival in Hq and WT mice subjected to pressure overload. EUK-8 also improved left ventricular end-systolic dimensions and fractional shortening, prevented myocardial oxidant stress, attenuated necrotic and apoptotic cell death, and attenuated cardiac hypertrophy and fibrosis in both mutant and WT mice.

CONCLUSIONS

The protection against pressure overload-induced heart failure in Hq mice by EUK-8 substantiates the notion that AIF functions as an important mitochondrial antioxidant in the heart. Furthermore, because antioxidant treatment protected both the oxidative stress-prone Hq mouse model and WT mice against pressure overload-induced maladaptive left ventricular remodeling and cardiac decompensation, it may be useful as a novel therapeutic tool in the treatment of human heart failure.

Increased apoptosis in rat brain after rapid eye movement sleep loss

Rapid eye movement (REM) sleep loss impairs several physiological, behavioral and cellular processes; however, the mechanism of action was unknown. To understand the effects of REM sleep deprivation on neuronal damage and apoptosis, studies were conducted using multiple apoptosis markers in control and experimental rat brain neurons located in areas either related to or unrelated to REM sleep regulation. Furthermore, the effects of REM sleep deprivation were also studied on neuronal cytoskeletal proteins, actin and tubulin. It was observed that after REM sleep deprivation a significantly increased number of neurons in the rat brain were positive to apoptotic markers, which however, tended to recover after the rats were allowed to undergo REM sleep; the control rats were not affected. Further, it was also observed that REM sleep deprivation decreased amounts of actin and tubulin in neurons confirming our previous reports of changes in neuronal size and shape after such deprivation. These findings suggest that one of the possible functions of REM sleep is to protect neurons from damage and apoptosis.

Vitamins C and E attenuate apoptosis, beta-adrenergic receptor desensitization, and sarcoplasmic reticular Ca2+ ATPase downregulation after myocardial infarction

Oxidative stress plays an important role in mediating ventricular remodeling and dysfunction in heart failure (HF), but its mechanism of action has not been fully elucidated. In this study we determined whether a combination of antioxidant vitamins reduced myocyte apoptosis, beta-adrenergic receptor desensitization, and sarcoplasmic reticular (SR) Ca2+ ATPase downregulation in HF after myocardial infarction (MI) and whether these effects were associated with amelioration of left ventricular (LV) remodeling and dysfunction. Vitamins (vitamin C 300 mg and vitamin E 300 mg) were administered to rabbits 1 week after MI or sham operation for 11 weeks. The results showed that MI rabbits exhibited cardiac dilation and LV dysfunction measured by fractional shortening and the maximal rate of pressure rise (dP/dt), an index of contractility. These changes were associated with elevation of oxidative stress, decreases of mitochondrial Bcl-2 and cytochrome c proteins, increases of cytosolic Bax and cytochrome c proteins, caspase 9 and caspase 3 activities and myocyte apoptosis, and downregulation of beta-adrenergic receptor sensitivity and SR Ca2+ ATPase. Combined treatment with vitamins C and E diminished oxidative stress, increased mitochondrial Bcl-2 protein, decreased cytosolic Bax, prevented cytochrome c release from mitochondria to cytosol, reduced caspase 9 and caspase 3 activities and myocyte apoptosis, blocked beta-adrenergic receptor desensitization and SR Ca2+ ATPase downregulation, and attenuated LV dilation and dysfunction in HF after MI. The results suggest that antioxidant therapy may be beneficial in HF.

Norepinephrine-induced oxidative stress causes PC-12 cell apoptosis by both endoplasmic reticulum stress and mitochondrial intrinsic pathway: inhibition of phosphatidylinositol 3-kinase survival pathway

Norepinephrine (NE) induces endoplasmic reticulum (ER) unfolded protein response and reduces maturation and translocation of NE transporter to cell membrane via enhanced formation of reactive oxygen species in PC-12 cells. In the present study, we investigated whether ER stress is also implicated in the proapoptotic effect of NE. We found that the apoptotic effect of NE was associated with increased processing of ER-resident pro-caspase-12, cleavage of caspase-9 and -3, and mitochondrial release of cytochrome c. ER stress was evidenced by upregulation of ER chaperone GRP78 and transcription factor CHOP and the translocation of XBP-1 from the ER to the nucleus by NE. NE also reduced phospho-Akt (Ser473), indicating suppression of the phosphatidylinositol 3-kinase (PI3-kinase)/Akt survival pathway. Similar results were produced by thapsigargin. NGF, which promotes the PI3-kinase/Akt activity, reduced the effects of NE and thapsigargin on apoptosis and activation of caspase-12 and -3. However, the effects of NE, but not of thapsigargin, were abolished by pretreatment with SOD and catalase. In contrast, the PI3-kinase inhibitors LY-294002 and wortmannin abolished the protective effects of both SOD/catalase and NGF on NE-induced apoptosis. The functional importance of caspase-12 activation was supported by the use of Z-ATAD-FMK, which reduced the NE-induced processing of caspase-12 and cell apoptosis, but the caspase-12, -9, and -3 inhibitors had no effects on the increase in cytosolic cytochrome c produced by NE. In contrast, the release of mitochondrial cytochrome c was abolished by SOD/catalase and NGF. These results indicate that NE induced cell apoptosis by both ER stress and a mitochondrial death pathway and that the effects of NE were mediated via oxidative stress and inhibition of the PI3-kinase/Akt survival pathway.

Inhibitory effect of trilinolein on endothelin-1-induced c-fos gene expression in cultured neonatal rat cardiomyocytes

Trilinolein, isolated from the traditional Chinese herb Sanchi (Panax notoginseng), has been shown to have myocardial protective effects via its antioxidant ability. However, the cellular and molecular mechanisms of the protective effect of trilinolein in the heart remain to be elucidated. Oxidative mechanisms have been implicated in neonatal cardiomyocyte hypertrophy. We previously reported that ET-1 induces ROS generation via the ET(A) receptor and ROS modulates c-fos gene expression. We have therefore examined whether trilinolein attenuates ROS production and ET-1-induced c-fos gene expression in cardiomyocytes. Cultured neonatal rat cardiomyocytes were stimulated with ET-1 (10 nM), and c-fos gene expression was examined. Trilinolein (1 and 10 microM) inhibited ET-1-induced c-fos gene expression in cardiomyocytes. We also examined the effects of trilinolein on ET-1-increased NADPH oxidase activity and superoxide formation. Trilinolein inhibited ET-1-increased NADPH oxidase activity and superoxide formation in a concentration-dependent manner. This increase in superoxide production by ET-1 was significantly inhibited by trilinolein, diphenyleneiodonium, or N-acetylcysteine. Trilinolein also decreased ET-1- or H2O2-induced extracellular signal-regulated kinase (ERK) phosphorylation, c-Jun NH2-terminal kinase (JNK) phosphorylation, and activator protein-1 activation. These data indicate that trilinolein inhibits ET-1-induced ERK phosphorylation, JNK phosphorylation, and c-fos gene expression via attenuating superoxide production in cardiomyocytes.

REDOX REGULATION BY INTRINSIC SPECIES AND EXTRINSIC NUTRIENTS IN NORMAL AND CANCER CELLS

Cells in multicellular organisms are exposed to both endogenous oxidative stresses generated metabolically and to oxidative stresses that originate from neighboring cells and from other tissues. To protect themselves from oxidative stress, cells are equipped with reducing buffer systems (glutathione/GSH and thioredoxin/thioredoxin reductase) and have developed several enzymatic mechanisms against oxidants that include catalase, superoxide dismutase, and glutathione peroxidase. Other major extrinsic defenses (from the diet) include ascorbic acid, beta-carotene and other carotenoids, and selenium. Recent evidence indicates that in addition to their antioxidant function, several of these redox species and systems are involved in regulation of biological processes, including cellular signaling, transcription factor activity, and apoptosis in normal and cancer cells. The survival and overall well-being of the cell is dependent upon the balance between the activity and the intracellular levels of these antioxidants as well as their interaction with various regulatory factors, including Ref-1, nuclear factor-kappaB, and activating protein-1.

Chronic beta-adrenoreceptor stimulation in vivo decreased Bcl-2 and increased Bax expression but did not activate apoptotic pathways in mouse heart

Prolonged activation of the sympathetic nervous system is deleterious to heart function. In vitro beta1-adrenergic activation promotes apoptosis, whereas beta2-adrenergic activation reduces apoptosis in cultured adult cardiomyocytes. To determine the effect of chronic catecholamine infusion in vivo, we measured apoptosis marker expression in C57Bl/6 and catecholamine-sensitive Egr-1 deficient mice after treatment with the nonspecific beta-adrenergic agonist, isoproterenol, the beta1-specific agonist, dobutamine, or the beta2-specific agonist, metaproterenol. Antiapoptotic and proapoptotic protein expression, cytochrome c release and caspases 3, 9, and 12 activation products were measured on immunoblots. Catecholamine-treated mice had decreased Bcl-2 and increased Bax and BNIP1 expression, suggesting mitochondria-dependent apoptosis pathway activation. However, cytosolic cytochrome c or caspase 3 or 9 activation products were not detected. In mice, increased molecular chaperone expression and caspase 12 activation characterize endoplasmic-reticulum-driven apoptosis. Clusterin expression was increased in catecholamine-treated mice, but GRP78 expression was not increased, and caspase 12 activation products were not detected. Thus, neither the mitochondrial nor the endoplasmic apoptotic pathway was fully activated. Further, Egr-1 deficiency did not increase cardiac apoptosis. We conclude that although chronic in vivo infusion of beta1- or beta2-adrenergic receptor agonists partially activates the apoptosis program, full activation of the caspase cascade requires more, or other, cardiac insults.

Intravenous catecholamine administration affects mouse intestinal lymphocyte number and apoptosis

The purposes of this study were to determine plasma and intestinal epinephrine (E) and norepinephrine (NE) concentrations in mice after exercise stress and, the effect of intravenous injection of E and NE (at concentrations during exercise) on viability of intestinal lymphocytes (IL). Exhaustive exercise significantly elevated plasma E and NE, and intestinal E, compared with sedentary animals. Twenty-four hours after intravenous NE administration, IL counts were higher (p<0.001) and % apoptotic IL were lower (p<0.001) than saline conditions. E resulted in fewer apoptotic IL at 24 h compared to saline controls. E and NE differentially influence IL numbers at 24 h after injection although both result in fewer % apoptotic IL relative to mice given saline only.

The inhibitory effect of trilinolein on norepinephrine-induced beta-myosin heavy chain promoter activity, reactive oxygen species generation, and extracellular signal-regulated kinase phosphorylation in neonatal rat cardiomyocytes

The myocardial protective effects of trilinolein, isolated from the traditional Chinese herb Sanchi (Panax notoginseng), are thought to be related to its antioxidant activity. However, the intracellular mechanism underlying the protective effect of trilinolein in the heart remains unclear. In the present study, we investigated the effect of trilinolein on norepinephrine (NE)-induced protein synthesis in cardiomyocytes. Cultured neonatal rat cardiomyocytes were stimulated with NE, then protein content, [(3)H]-leucine incorporation, and beta-myosin heavy chain (beta-MyHC) promoter activity were examined. The effect of trilinolein on NE-induced intracellular reactive oxygen species (ROS) generation was measured with a redox- sensitive fluorescent dye (2',7'-dichlorofluorescin diacetate) and extracellular signal-regulated kinase (ERK) phosphorylation by Western blotting. Trilinolein inhibited NE-increased protein synthesis, beta-MyHC promoter activity, and intracellular ROS. Both trilinolein and the antioxidant, N-acetyl-cysteine, decreased NE- and H(2)O(2)-induced protein synthesis, beta-MyHC promoter activity, and ERK phosphorylation. These data indicate that trilinolein inhibits NE-induced protein synthesis via attenuation of ROS generation in cardiomyocytes.

Modulation of apoptotic signalling by carotenoids in cancer cells

There is a growing body of literature on the role of beta-carotene and other carotenoids in human chronic diseases, including cancer. While epidemiological evidence shows that a high dietary intake of fruits and vegetables rich in carotenoids is associated with a reduced risk for cancer, results from intervention trials indicate that supplemental beta-carotene enhances the risk of developing lung cancer incidence and mortality among smokers. A possible mechanism which can explain the dual role of carotenoids as both beneficial and harmful agents in cancer is that their excess or deficiency may bring about changes in molecular pathways involved in apoptotic signalling. Carotenoid ability in inhibiting or in enhancing apoptosis depends on several factors: carotenoid concentration, concerted action of multiple micronutrients, cell type, and redox status. This review summarizes the available evidence for a modulatory action of carotenoids on apoptosis and focuses on the main molecular pathways involved in this process.

Importance of antioxidant and antiapoptotic effects of β-receptor blockers in heart failure therapy

The present study was carried out to determine whether beneficial effects of carvedilol in congestive heart failure (CHF) are mediated via its β-adrenergic blocking, antioxidant, and/or α-adrenergic blocking action. Rabbits with heart failure induced by rapid cardiac pacing were randomized to receive subcutaneous carvedilol, metoprolol, propranolol plus doxazosin, or placebo pellets for 8 wk and compared with sham-operated rabbits without pacing. We found rapid cardiac pacing produced clinical heart failure, left ventricular dilation, and decline of left ventricular fractional shortening. This was associated with an increase in left ventricular end-diastolic pressure, decrease in left ventricular first derivative of left ventricular pressure, and myocyte hypertrophy. Tissue oxidative stress measured by GSH/GSSG was increased in the heart with increased oxidation product of mitochondrial DNA, 8-oxo-7,8-dihydro-2′-deoxyguanosine, increase of Bax, decrease of Bcl-2, and increase of apoptotic myocytes as measured by anti-single-stranded DNA monoclonal antibody. Administration of carvedilol and metoprolol, which had no effect in sham animals, attenuated cardiac ventricular remodeling, cardiac hypertrophy, oxidative stress, and myocyte apoptosis in CHF. In contrast, propranolol plus doxazosin, which has less antioxidant effects, produced smaller effects on left ventricular function and myocyte apoptosis. In all animals, GSH/GSSG correlated significantly with changes of left ventricular end-diastolic dimension ( r = −0.678, P < 0.0001), fractional shortening ( r = 0.706, P < 0.0001), and apoptotic myocytes ( r = −0.473, P = 0.0001). Thus our findings suggest antioxidant and antiapoptotic actions of carvedilol and metoprolol are important determinants of clinical beneficial effects of β-receptors in the treatment of CHF.

Diabetic cardiomyopathy: evidence, mechanisms, and therapeutic implications

The presence of a diabetic cardiomyopathy, independent of hypertension and coronary artery disease, is still controversial. This systematic review seeks to evaluate the evidence for the existence of this condition, to clarify the possible mechanisms responsible, and to consider possible therapeutic implications. The existence of a diabetic cardiomyopathy is supported by epidemiological findings showing the association of diabetes with heart failure; clinical studies confirming the association of diabetes with left ventricular dysfunction independent of hypertension, coronary artery disease, and other heart disease; and experimental evidence of myocardial structural and functional changes. The most important mechanisms of diabetic cardiomyopathy are metabolic disturbances (depletion of glucose transporter 4, increased free fatty acids, carnitine deficiency, changes in calcium homeostasis), myocardial fibrosis (association with increases in angiotensin II, IGF-I, and inflammatory cytokines), small vessel disease (microangiopathy, impaired coronary flow reserve, and endothelial dysfunction), cardiac autonomic neuropathy (denervation and alterations in myocardial catecholamine levels), and insulin resistance (hyperinsulinemia and reduced insulin sensitivity). This review presents evidence that diabetes is associated with a cardiomyopathy, independent of comorbid conditions, and that metabolic disturbances, myocardial fibrosis, small vessel disease, cardiac autonomic neuropathy, and insulin resistance may all contribute to the development of diabetic heart disease.

Extracellular norepinephrine reduces neuronal uptake of norepinephrine by oxidative stress in PC12 cells

Cardiac norepinephrine (NE) uptake activity is reduced in congestive heart failure. Our studies in intact animals suggest that this effect on the cardiac sympathetic nerve endings is caused by oxidative stress and/or NE toxic metabolites derived from NE. In this study, we investigated the direct effects of NE on neuronal NE uptake activity and NE transporter (NET), using undifferentiated PC12 cells. Cells were incubated with NE (1–500 μM) either alone or in combination of Cu2+ sulfate (1 μM), which promotes free radical formation by Fenton reaction for 24 h. NE uptake activity was measured using [3H]NE. Cell viability was determined with the use of Trypan blue exclusion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay, and cellular oxidative stress by dichlorodihydrofluorescein fluorescence and the GSH/GSSG ratio. Cell viability was reduced by NE >100 μM. At lower doses, NE produced oxidative stress and a dose-dependent reduction of NE uptake activity without affecting cell viability significantly. Cu2+, which has no direct effect on NE uptake activity, potentiated oxidative stress and reduction of NE uptake activity produced by NE. This decrease of NE uptake activity was associated with reductions of NE uptake binding sites and NET protein expression by using the radioligand assay and Western blot analysis, but no changes in NET gene expression. In addition, the free-radical scavenger mannitol, and antioxidant enzymes superoxide dismutase and catalase, reduced oxidative stress and attenuated the reductions of NE uptake activity and NET protein produced by NE/Cu. Thus our results support a functional role of oxidative stress in mediating the neuronal NE uptake reducing effect of NE and that this effect of NE on NET is a posttranscriptional event.

Pycnogenol® and vitamin E inhibit ethanol-induced apoptosis in rat cerebellar granule cells

Pycnogenol (PYC), a patented combination of bioflavonoids extracted from the bark of French maritime pine (Pinus maritima), scavenges free radicals and promotes cellular health. The protective capacity of PYC against ethanol toxicity of neurons has not previously been explored. The present study demonstrates that in postnatal day 9 (P9) rat cerebellar granule cells the antioxidants vitamin E (VE) and PYC (1) dose dependently block cell death following 400, 800, and 1600 mg/dL ethanol exposure (2) inhibit the ethanol-induced activation of caspase-3 in the same model system; and (3) reduce neuronal membrane disruption as assayed by phosphatidylserine translocation to the cell surface. These results suggest that both PYC and VE have the potential to act as therapeutic agents, antagonizing the induction of neuronal cell death by ethanol exposure.

Myocyte contractile activity modulates norepinephrine cytotoxicity and survival effects of neuregulin-1β

The purpose of this study is to test the hypothesis that mechanical and electrical activity in adult rat ventricular myocytes (ARVM) alters responses to proapoptotic and prosurvival ligands. The effects of electrical stimulation on myocyte survival, stress signaling, response to β-adrenergic receptor (β-AR)-stimulated apoptosis, and neuregulin-1β (NRG) were examined. Electrical stimulation (6.6 V/cm; 0, 2, and 5 Hz; 2-ms duration; alternating polarity) of ARVM resulted in more than 70% capture. Although ARVM paced for 48 h showed higher mitochondrial uptake of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide ( P < 0.05, 0 vs. 2 and 5 Hz), electrical stimulation had little effect on cell survival assessed by trypan blue uptake, CPK release, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. Electrical stimulation for 24 h did not induce stress response (heat shock protein 70, 90) nor stress kinase (Erk, JNK, p38) activation. NRG stimulation of Erk and Akt was similar between paced and quiescent cells. Pacing sensitized myocytes to β-AR-stimulated JNK phosphorylation and cell death with 0.1 μM norepinephrine (NE) in paced myocytes causing equivalent cytotoxicity to 10 μM NE in quiescent cells. NRG suppressed β-AR-induced apoptosis through a phosphatidylinositol-3-kinase-dependent pathway in both paced and quiescent cells, although it is overwhelmed by high-NE concentration in paced cells. Thus myocyte contractility modulates both NE cytotoxicity as well as the cytoprotective effect of NRG. These results demonstrate the feasibility and importance of using electrically paced cardiomyocytes in primary culture when examining the signaling pathways of cell survival.

Rationale, Design, and Organization of the Diastolic Heart Failure Assessment Study in Tohoku District (DIAST)

BACKGROUND

High mortality and a high readmission rate characterize diastolic heart failure (DHF), but evidence-based therapeutic strategies have not been established for DHF.

METHODS

The aim of a multicenter, randomized open trial (the Diastolic Heart Failure Assessment Study in Tohoku District, DIAST) is to evaluate the safety and prognostic efficacy of the multiple action non-selective beta-blocker carvedilol in 160 patients with DHF (left-ventricular ejection fraction > or =50%). The target dose of carvedilol is 10 mg twice a day and the mean follow-up is estimated to be 2 years. The primary endpoints are to evaluate (1) all-cause mortality or hospitalization, (2) cardiovascular mortality or hospitalization and (3) worsening heart failure. The secondary endpoints are to assess (1) cardiovascular events, (2) the individual components of the above combined endpoints, (3) the duration of hospitalization, (4) the functional class and exercise capacity and (5) the safety and tolerability. All patients' data are processed using an original registration system on an internet homepage. Several substudies to assess neurohumoral factors, heart rate variability, oxidative stress and sleep apnea will clarify the pathophysiology of DHF.

CONCLUSIONS

The DIAST will contribute to establish therapeutic guidelines for DHF.

Do β-blockers prolong survival in heart failure only by inhibiting the β1-receptor? A perspective on the results of the COMET trial

Experimental and clinical studies indicate that carvedilol exerts multiple antiadrenergic effects in addition to beta(1)-receptor blockade, but the prognostic importance of these actions has long been debated. This controversy has now been substantially advanced by the results of the recently completed Carvedilol Or Metoprolol European Trial (COMET), which showed that carvedilol (25 mg twice daily) reduced mortality by 17% when compared with metoprolol (50 mg twice daily), P=.0017--a result that was consistent with the differences seen across earlier controlled trials with beta-blockers in survivors of an acute myocardial infarction and in patients with chronic heart failure. Questions have been raised about the interpretation of these findings in view of the fact that the trial did not use the dose or formulation of metoprolol that was shown to prolong life in a placebo-controlled trial (ie, Metoprolol CR/XL [Controlled Release] Randomized Intervention Trial in Heart Failure). Pharmacokinetic and pharmacodynamic analyses, however, indicate that the dosing regimen of metoprolol selected for use in the COMET trial produces a magnitude and time course of beta(1)-blockade during a 24-hour period that is similar to the dose of carvedilol targeted for use in the trial. These analyses suggest that the observed difference in the mortality effects of metoprolol and carvedilol is not related to a difference in the magnitude or time course of their beta(1)-blocking effects but instead reflect antiadrenergic effects of carvedilol in addition to beta(1)-blockade.

Antioxidants attenuate myocyte apoptosis and improve cardiac function in CHF: association with changes in MAPK pathways

Antioxidant vitamins reduce cardiac oxidative stress and cardiomyocyte apoptosis produced by exogenous norepinephrine (NE) and attenuate cardiac dysfunction in animals with pacing-induced congestive heart failure (CHF). This study was carried out to determine whether the mitogen-activated protein kinase (MAPK) signal transduction pathways are involved in oxidative stress-induced myocyte apoptosis. Rabbits with rapid pacing-induced CHF and sham operation were randomized to receive either a combination of antioxidant vitamins (beta-carotene, ascorbic acid, and alpha-tocopherol), alpha-tocopherol alone, or placebo for 8 wk. Compared with sham-operated animals, CHF animals exhibited increased oxidative stress as evidenced by decreased myocardial reduced-to-oxidized glutathione (GSH/GSSG) ratio (27 +/- 7 vs. 143 +/- 24, P < 0.05), myocyte apoptosis (77 +/- 18 vs. 17 +/- 4 apoptotic nuclei/10,000 cardiomyocytes, P < 0.05), increased total and phosphorylated c-Jun NH2-terminal protein kinase (p-JNK; 1.95 +/- 0.14 vs. 1.04 +/- 0.04 arbitrary units, P < 0.05) and phosphorylated p38 kinase (p-p38), and decreased phosphorylated extracellular signal-regulated kinase (p-ERK). Administration of antioxidant vitamins and alpha-tocopherol attenuated oxidative stress, myocyte apoptosis, and cardiac dysfunction, with reversal of the changes of total JNK, p-JNK, and p-ERK in CHF. Furthermore, because NE infusion produced changes of JNK, p-p38, and p-ERK similar to those in CHF, we conclude that NE may play an important role in the production of oxidative stress, MAPK activation, and myocyte apoptosis in CHF.

Alterations in myocardial cytoskeletal and regulatory protein expression following a single Doxorubicin injection

Immunochemical and ultrastructural studies of the rat heart after a single injection of doxorubicin (2.2 or 0.44 mg/kg) were performed. Ventricles were taken for the study 2 h and 3 weeks after injection. The light and electron microscopy and immunohistochemical determination of collagens of I, III, and IV types and fibronectin using specific antibodies were implied. Quantitive immunoblotting was used to analyze the expression levels of cytoskeletal and extracellular matrix proteins such as desmin, tubulin, vinculin, fibronectin, kinase-related protein (KRP or telokin), and smooth muscle/nonmuscle myosin light-chain kinase (MLCK). Doxorubicin (2.2 mg/kg) did not influence the relative volume and structure of collagen network but distinctly reduced the density of fibronectin distribution and decreased the content of tubulin, fibronectin, MLCK, and KRP. After 3 weeks, an increased density and extension of collagen network were observed, indicating the development of diffuse fibrosis whereas the content of tubulin and KRP increased above control level by 50 +/- 2.3% and 20 +/- 5.2%, correspondingly. Similar but less pronounced alterations were observed following the administration of 0.44 mg/kg doxorubicin. The content of MLCK after both doses consistently remained about 30% below its level in untreated animals. Isolated chick embryo cardiomyocytes subjected to doxorubicin responded by a 26% increase in KRP expression 4 days after whereas the level of tubulin expression remained unchanged. Thus, the damage of myocardium after a single injection of a therapeutic dose of doxorubicin was followed by an increased expression of selected cytoskeletal and extracellular matrix proteins, suggesting their involvement in cardiac reparation.

Anticonvulsant valproic acid inhibits cardiomyocyte differentiation of embryonic stem cells by increasing intracellular levels of reactive oxygen species

BACKGROUND

The anticonvulsant valproic acid (VPA) exerts teratogenic properties and has been demonstrated to cause neural tube defects and malformations of the heart. The effect of VPA on the differentiation of cardiomyocytes from pluripotent murine embryonic stem cells (ES cells) was investigated.

METHODS

Embryoid bodies derived from ES cells were treated with different concentrations of VPA and the differentiation of cardiomyocytes was monitored by immunohistochemical staining for sarcomeric alpha-actinin. Cytotoxicity was evaluated by the use of the dead cell stain SYTOX green. Intracellular levels of reactive oxygen species (ROS) within the tissue were evaluated by the use of the redox-sensitive dye dichlorodihydrofluorescein diacetate (H2DCFDA).

RESULTS

VPA retarded the growth of ES cell-derived embryoid bodies but did not exert cytotoxic effects. The compound dose-dependently inhibited the development of spontaneously beating clusters of cardiomyocytes within embryoid bodies grown from ES cells and reduced the extension of beating areas of cardiac cells. Furthermore, VPA significantly increased ROS levels, indicating that VPA altered the intracellular redox balance. To investigate whether the inhibition of cardiomyocyte differentiation by VPA was owing to increased ROS overwhelming the intracellular antioxidative defense, the compound was coadministered with the free radical scavenger vitamin E.

CONCLUSIONS

This treatment significantly restored cardiomyogenic differentiation, indicating that VPA inhibits cardiomyogenesis of ES cells by increasing intracellular ROS levels.

Selegiline attenuates cardiac oxidative stress and apoptosis in heart failure: association with improvement of cardiac function

We have shown recently that selegiline exerts a cardiac neuroprotective effect in chronic heart failure. Since selegiline has an antioxidant antiapoptotic effect, we proposed to determine whether selegiline attenuates cardiac oxidative stress and myocyte apoptosis in chronic heart failure by modulating Bcl-2 and Bax protein expression, and whether the effects are associated with the improvement of cardiac function. Rabbits with rapid cardiac pacing (360 beats/min) and sham operation without pacing were randomized to receive oral selegiline (1 mg/day) or placebo for 8 weeks. Echocardiography was used to measure left ventricular fractional shortening. After 8 weeks of treatment, animals were studied for arterial norepinephrine and left ventricular systolic function (fractional shortening and dP/dt), and were then sacrificed for measuring the stable oxidative product of myocardial mitochondrial DNA (mtDNA) 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), myocyte apoptosis by monoclonal antibody to single stranded DNA, and Bcl-2 and Bax protein expression by Western blot and immunohistochemistry. Rapid cardiac pacing increased plasma norepinephrine, cardiac oxidative stress and myocyte apoptosis, reduced Bcl-2 and the Bcl-2 to Bax ratio. These changes were associated with decreased left ventricular fractional shortening and dP/dt. Selegiline treatment in chronic heart failure animals reduced plasma norepinephrine, cardiac oxidative stress and myocyte apoptosis, prevented the changes of Bcl-2 and Bcl-2 to Bax ratio, and improved left ventricular fractional shortening and dP/dt. The findings suggest that the reduction by selegiline of myocyte apoptosis is related to the decrease of cardiac oxidative stress and the modulation of apoptotic and antiapoptotic proteins. The antioxidant antiapoptotic effects of selegiline are potentially beneficial in the improvement of cardiac function in chronic heart failure.

Nutritional abnormalities contributing to cachexia in chronic illness

Cachexia is a common consequence of chronic illness. The nutritional abnormalities contributing to the clinical picture are often a composite of reduced appetite, dietary factors including protein, energy and micronutrient intake, malabsorption and increased consumption or loss of nutrients. In this article, using chronic heart failure as an example, we have reviewed the potential influences of chronic disease on each of these and how they might lead to the relentless progression of wasting and the poor prognosis associated with it.

Carvedilol decreases elevated oxidative stress in human failing myocardium

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of heart failure. However, direct evidence of oxidative stress generation in the human failing myocardium has not been obtained. Furthermore, the effect of carvedilol, a vasodilating beta-blocker with antioxidant activity, on oxidative stress in human failing hearts has not been assessed. This study was therefore designed to determine whether levels of lipid peroxides are elevated in myocardia of patients with dilated cardiomyopathy (DCM) and whether carvedilol reduces the lipid peroxidation level. Methods and Results- Endomyocardial biopsy samples obtained from 23 patients with DCM and 13 control subjects with normal cardiac function were studied immunohistochemically for the expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. Expression of HNE-modified protein was found in all myocardial biopsy samples from patients with DCM. Expression was distinct in the cytosol of cardiac myocytes. Myocardial HNE-modified protein levels in patients with DCM were significantly increased compared with the levels in control subjects (P<0.0001). Endomyocardial biopsy samples from 11 patients with DCM were examined before and after treatment (mean, 9+/-4 months) with carvedilol (5 to 30 mg/d; mean dosage, 22+/-8 mg/d). After treatment with carvedilol, myocardial HNE-modified protein levels decreased by 40% (P<0.005) along with amelioration of heart failure.

CONCLUSIONS

Oxidative stress is elevated in myocardia of patients with heart failure. Administration of carvedilol resulted in a decrease in the oxidative stress level together with amelioration of cardiac function.

Microarray analysis reveals an antioxidant responsive element-driven gene set involved in conferring protection from an oxidative stress-induced apoptosis in IMR-32 cells

The present study was designed to investigate how tert-butylhydroquinone (tBHQ) prevents hydrogen peroxide-induced apoptosis in IMR-32 cells. tBHQ pretreatment (10 microm) attenuated hydrogen peroxide-induced cell death and reduced the number of TUNEL (terminal deoxynucleotidyltransferase-mediated, dUTP-incorporated nick end labeling)-positive cells. We hypothesize that tBHQ-mediated activation of the antioxidant responsive element is critical for generating this protective response. Addition of LY294002, a selective inhibitor of phosphatidylinositol 3-kinase (PI3K), 30 min prior to tBHQ treatment completely reversed the protective effect of tBHQ. Oligonucleotide microarrays were used to analyze the gene expression profile associated with tBHQ treatment in the absence and presence of LY294002. Ranking analysis using Affymetrix's difference call indicated that the expression of 137 genes changed with tBHQ treatment. Further analysis using the coefficient of variation for -fold change or average difference change reduced the list to 63 increased and 0 decreased genes. Reverse transcription-PCR for selected genes also confirmed the gene expression pattern. Many of these genes function to combat oxidative stress and increase the detoxification potential of the cells. Inhibition of PI3K significantly blocked the enhanced expression of 49 of the 63 genes induced by tBHQ. These data are the first to show a set of programmed cell life genes involved in conferring protection from an oxidative stress-induced apoptosis.