N-acetylcysteine improves coronary and peripheral vascular function

N-Acetylcysteine and Atherosclerosis: Promises and Challenges

Atherosclerosis remains a leading cause of cardiovascular diseases. Although the mechanism for atherosclerosis is complex and has not been fully understood, inflammation and oxidative stress play a critical role in the development and progression of atherosclerosis. N-acetylcysteine (NAC) has been used as a mucolytic agent and an antidote for acetaminophen overdose with a well-established safety profile. NAC has antioxidant and anti-inflammatory effects through multiple mechanisms, including an increase in the intracellular glutathione level and an attenuation of the nuclear factor kappa-B mediated production of inflammatory cytokines like tumor necrosis factor-alpha and interleukins. Numerous animal studies have demonstrated that NAC significantly decreases the development and progression of atherosclerosis. However, the data on the outcomes of clinical studies in patients with atherosclerosis have been limited and inconsistent. The purpose of this review is to summarize the data on the effect of NAC on atherosclerosis from both pre-clinical and clinical studies and discuss the potential mechanisms of action of NAC on atherosclerosis, as well as challenges in the field.

N-Acetylcysteine and Its Immunomodulatory Properties in Humans and Domesticated Animals

N-acetylcysteine (NAC), an acetylated derivative of the amino acid L-cysteine, has been widely used as a mucolytic agent and antidote for acetaminophen overdose since the 1960s and the 1980s, respectively. NAC possesses antioxidant, cytoprotective, anti-inflammatory, antimicrobial, and mucolytic properties, making it a promising therapeutic agent for a wide range of diseases in both humans and domesticated animals. Oxidative stress and inflammation play a major role in the onset and progression of all these diseases. NAC's primary role is to replenish glutathione (GSH) stores, the master antioxidant in all tissues; however, it can also reduce levels of pro-inflammatory tumor necrosis factor-alpha (TNF-∝) and interleukins (IL-6 and IL-1β), inhibit the formation of microbial biofilms and destroy biofilms, and break down disulfide bonds between mucin molecules. Many experimental studies have been conducted on the use of NAC to address a wide range of pathological conditions; however, its effectiveness in clinical trials remains limited and studies often have conflicting results. The purpose of this review is to provide a concise overview of promising NAC usages for the treatment of different human and domestic animal disorders.

N-Acetylcysteine: more than preventing contrast-induced nephropathy in uremic patients-focus on the antioxidant and anti-inflammatory properties

Oxidative stress (OS) has been recognized as a pathophysiologic mechanism underlying the development and progression of chronic kidney disease (CKD). OS, which results from the disturbance of balance among pro-oxidants and antioxidants favoring the pro-oxidants, is present even in early CKD and increases progressively along with deterioration of kidney function to end-stage kidney disease (ESKD). In ESKD, OS is further exacerbated mainly due to dialysis procedures per se and predisposes to increased cardiovascular morbidity and mortality. Therefore, since OS plays a pivotal role in the pathogenesis and progression of atherosclerosis in uremic patients, several strategies aiming to ameliorate OS in these patients have been proposed. Among those, N-acetylcysteine (NAC), a thiol-containing antioxidant agent, has attracted special attention due to its pleiotropic functions and beneficial effect in various OS-related entities including paracetamol overdose and prevention of contrast-induced nephropathy. In this review, we present the currently available literature on the antioxidant and anti-inflammatory properties of NAC in CKD, including hemodialysis and peritoneal dialysis.

High-Intensity Exercise Training Alters the Effect of N-Acetylcysteine on Exercise-Related Muscle Ionic Shifts in Men

This study investigated whether high-intensity exercise training alters the effect of N-acetylcysteine (a precursor of antioxidant glutathione) on exercise-related muscle ionic shifts. We assigned 20 recreationally-active men to 6 weeks of high-intensity exercise training, comprising three weekly sessions of 4-10 × 20-s all-out bouts interspersed by 2 min recovery (SET, n = 10), or habitual lifestyle maintenance (n = 10). Before and after SET, we measured ionic shifts across the working muscle, using leg arteriovenous balance technique, during one-legged knee-extensor exercise to exhaustion with and without N-acetylcysteine infusion. Furthermore, we sampled vastus lateralis muscle biopsies for analyses of metabolites, mitochondrial respiratory function, and proteins regulating ion transport and antioxidant defense. SET lowered exercise-related H⁺, K⁺, lactate^-, and Na⁺ shifts and enhanced exercise performance by ≈45%. While N-acetylcysteine did not affect exercise-related ionic shifts before SET, it lowered H⁺, HCO₃^-, and Na⁺ shifts after SET. SET enhanced muscle mitochondrial respiratory capacity and augmented the abundance of Na⁺/K⁺-ATPase subunits (α₁ and β₁), ATP-sensitive K⁺ channel subunit (Kir6.2), and monocarboxylate transporter-1, as well as superoxide dismutase-2 and glutathione peroxidase-1. Collectively, these findings demonstrate that high-intensity exercise training not only induces multiple adaptations that enhance the ability to counter exercise-related ionic shifts but also potentiates the effect of N-acetylcysteine on ionic shifts during exercise.

Endothelial dysfunction: developmental mechanisms and therapeutic strategies

Introduction: Every year the importance of the normal functioning of the endothelial layer of the vascular wall in maintaining the health of the body becomes more and more obvious.

The physiological role of the endothelium: The endothelium is a metabolically active organ actively involved in the regulation of hemostasis, modulation of inflammation, maintenance of hemovascular homeostasis, regulation of angiogenesis, vascular tone, and permeability.

Risk factors for the development of endothelial dysfunction: Currently, insufficient bioavailability of nitric oxide is considered the most significant risk factor for endothelial dysfunction.

Mechanisms of development of endothelial dysfunction: The genesis of endothelial dysfunction is a multifactorial process. Among various complex mechanisms, this review examines oxidative stress, inflammation, hyperglycemia, vitamin D deficiency, dyslipidemia, excess visceral fat, hyperhomocysteinemia, hyperuricemia, as well as primary genetic defect of endotheliocytes, as the most common causes in the population underlying the development of endothelial dysfunction.

Markers of endothelial dysfunction in various diseases: This article discusses the main biomarkers of endothelial dysfunction currently used, as well as promising biomarkers in the future for laboratory diagnosis of this pathology.

Therapeutic strategies: Therapeutic approaches to the endothelium in order to prevent or reduce a degree of damage to the vascular wall are briefly described.

Conclusion: Endothelial dysfunction is a typical pathological process involved in the pathogenesis of many diseases. Thus, pharmacological agents with endothelioprotective properties can provide more therapeutic benefits than a drug without such an effect.

Glutathione: A Samsonian life-sustaining small molecule that protects against oxidative stress, ageing and damaging inflammation

Many local and systemic diseases especially diseases that are leading causes of death globally like chronic obstructive pulmonary disease, atherosclerosis with ischemic heart disease and stroke, cancer and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 19 (COVID-19), involve both, (1) oxidative stress with excessive production of reactive oxygen species (ROS) that lower glutathione (GSH) levels, and (2) inflammation. The GSH tripeptide (γ- L-glutamyl-L-cysteinyl-glycine), the most abundant water-soluble non-protein thiol in the cell (1-10 mM) is fundamental for life by (a) sustaining the adequate redox cell signaling needed to maintain physiologic levels of oxidative stress fundamental to control life processes, and (b) limiting excessive oxidative stress that causes cell and tissue damage. GSH activity is facilitated by activation of the Kelch-like ECH-associated protein 1 (Keap1)-Nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) redox regulator pathway, releasing Nrf2 that regulates expression of genes controlling antioxidant, inflammatory and immune system responses. GSH exists in the thiol-reduced (>98% of total GSH) and disulfide-oxidized (GSSG) forms, and the concentrations of GSH and GSSG and their molar ratio are indicators of the functionality of the cell. GSH depletion may play a central role in inflammatory diseases and COVID-19 pathophysiology, host immune response and disease severity and mortality. Therapies enhancing GSH could become a cornerstone to reduce severity and fatal outcomes of inflammatory diseases and COVID-19 and increasing GSH levels may prevent and subdue these diseases. The life value of GSH makes for a paramount research field in biology and medicine and may be key against systemic inflammation and SARS-CoV-2 infection and COVID-19 disease. In this review, we emphasize on (1) GSH depletion as a fundamental risk factor for diseases like chronic obstructive pulmonary disease and atherosclerosis (ischemic heart disease and stroke), (2) importance of oxidative stress and antioxidants in SARS-CoV-2 infection and COVID-19 disease, (3) significance of GSH to counteract persistent damaging inflammation, inflammaging and early (premature) inflammaging associated with cell and tissue damage caused by excessive oxidative stress and lack of adequate antioxidant defenses in younger individuals, and (4) new therapies that include antioxidant defenses restoration.

Updates on Pharmacologic Management of Microvascular Angina

Microvascular angina (MVA), historically called cardiac syndrome X, refers to angina with nonobstructive coronary artery disease. This female-predominant cardiovascular disorder adds considerable health-related costs due to repeated diagnostic angiography and frequent hospital admissions. Despite the high prevalence of this diagnosis in patients undergoing coronary angiography, it is still a therapeutic challenge for cardiologists. Unlike obstructive coronary artery disease, with multiple evidence-based therapies and management guidelines, little is known regarding the management of MVA. During the last decade, many therapeutic interventions have been suggested for the treatment of MVA. However, there is a lack of summarization tab and update of current knowledge about pharmacologic management of MVA, mostly due to unclear pathophysiology. In this article, we have reviewed the underlying mechanisms of MVA and the outcomes of various medications in patients with this disease. Contrary to vasospastic angina in which normal angiogram is observed as well, nitrates are not effective in the treatment of MVA. Beta-blockers and calcium channel blockers have the strongest evidence of improving the symptoms. Moreover, the use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, statins, estrogen, and novel antianginal drugs has had promising outcomes. Investigations are still ongoing for vitamin D, omega-3, incretins, and n-acetyl cysteine, which have resulted in beneficial initial outcomes. We believe that the employment of the available results and results of the future large-scale trials into cardiac care guidelines would help reduce the global cost of cardiac care tremendously.

N-acetylcysteine attenuates atherosclerosis progression in aging LDL receptor deficient mice with preserved M2 macrophages and increased CD146

BACKGROUND AND AIMS

Inflammation and reactive oxygen species (ROS) are important to the pathogenesis of atherosclerosis. The effect of antioxidants on atherosclerosis is inconsistent, and sometimes controversial. We aimed to test the hypothesis that attenuation of atherosclerosis by N-acetylcysteine (NAC) depends on NAC treatment timing and duration.

METHODS

Male LDL receptor deficient (LDLR^-/-) mice were fed a normal diet (ND) and divided into controls (on ND for 24 months), models 1-2 (at age of 9 months, starting NAC treatment for 3 or 6 months), and model 3 (at age of 18 months, starting NAC treatment for 6 months). To determine if hyperlipidemia compromises NAC treatment outcome, mice were fed a high fat diet (HFD) starting at age of 6 weeks and treated with NAC starting at 9 months of age for 6 months.

RESULTS

NAC treatment for 6 months, not for 3 months, significantly attenuated atherosclerosis progression, but did not reverse atherosclerotic lesions, in aging LDLR^-/- mice on ND. NAC had no effect on atherosclerotic lesions in mice on HFD. NAC treatment significantly decreased aortic ROS production, and the levels of inflammatory cytokines in serum and aorta of aging LDLR^-/- mice with increased CD146 level. Bone marrow transplantation study with GFP-positive bone marrow cells showed that NAC treatment preserved M2 population and M2 polarization in the aorta of LDLR^-/- mice.

CONCLUSIONS

Early and adequate NAC treatment could effectively attenuate inflammation and atherosclerosis progression with preserved M2 population and increased CD146 level in aging LDLR^-/- mice without extreme hyperlipidemia.

Effects of N-acetylcysteine supplementation on disease activity, oxidative stress, and inflammatory and metabolic parameters in rheumatoid arthritis patients: a randomized double-blind placebo-controlled trial

Considering the importance of inflammation and oxidative stress in the development of rheumatoid arthritis (RA) as well as anti-inflammatory and antioxidant features of N-acetylcysteine (NAC), this study was conducted to evaluate the effect of NAC supplementation on disease activity, oxidative stress, and inflammatory and metabolic parameters in RA patients. In a randomized double-masked placebo-controlled trial, 74 RA subjects were chosen and randomly divided into two groups to take 600 mg of NAC or placebo twice daily for 3 months. Before and after the study, disease activity was assessed via disease activity score-28 (DAS-28), and serum malondialdehyde (MDA), total antioxidant capacity (TAC), glutathione peroxidase (GPX) activity, nitric oxide (NO), high-sensitivity C-reactive protein (hs-CRP), fasting blood sugar (FBS), lipid profile, and erythrocyte sedimentation rate (ESR) were measured. Seventy patients completed the trial. Compared to baseline, NAC significantly reduced morning stiffness (P < 0.001), DAS-28 (P < 0.001), ESR (P = 0.004), MDA (P < 0.001), NO (P < 0.001), hs-CRP (P = 0.006), FBS (P < 0.001), and low-density lipoprotein cholesterol (LDL-C) (P = 0.023) and significantly increased GPx activity (P = 0.015) and high-density lipoprotein cholesterol (HDL-C) level (P = 0.001). After treatment, remarkable differences were only seen between the two groups in serum NO (P = 0.003), FBS (P = 0.010), and HDL-C (P < 0.001) adjusted for baseline measures. There were no significant changes in morning stiffness, DAS-28, ESR, hs-CRP, MDA, TAC, GPx activity, triglyceride, total cholesterol, and LDL-C levels compared to the placebo group. In conclusion, NAC did not improve RA disease activity, but reduced NO and FBS and increased HDL-C levels. It appears that NAC should not be consumed as a replacement for routine medications prescribed in RA therapy, but it can be used as an adjunctive therapy.

Mechanisms of Impaired Lung Development and Ciliation in Mannosidase-1-Alpha-2 (Man1a2) Mutants

BACKGROUND

Ciliary defects cause heterogenous phenotypes related to mutation burden which lead to impaired development. A previously reported homozygous deletion in the Man1a2 gene causes lethal respiratory failure in newborn pups and decreased lung ciliation compared with wild type (WT) pups. The effects of heterozygous mutation, and the potential for rescue are not known.

PURPOSE

We hypothesized that survival and lung ciliation, (a) would decrease progressively in Man1a2 +/- heterozygous and Man1a2 -/- null newborn pups compared with WT, and (b) could be enhanced by gestational treatment with N-Acetyl-cysteine (NAC), an antioxidant.

METHODS

Man1a2+/- adult mice were fed NAC or placebo from a week before breeding through gestation. Survival of newborn pups was monitored for 24 h. Lungs, liver and tails were harvested for morphology, genotyping, and transcriptional profiling.

RESULTS

Survival (p = 0.0001, Kaplan-Meier) and percent lung ciliation (p = 0.0001, ANOVA) measured by frequency of Arl13b+ respiratory epithelial cells decreased progressively, as hypothesized. Compared with placebo, gestational NAC treatment enhanced (a) lung ciliation in pups with each genotype, (b) survival in heterozygous pups (p = 0.017) but not in WT or null pups. Whole transcriptome of lung but not liver demonstrated patterns of up- and down-regulated genes that were identical in living heterozygous and WT pups, and completely opposite to those in dead heterozygous and null pups. Systems biology analysis enabled reconstruction of protein interaction networks that yielded functionally relevant modules and their interactions. In these networks, the mutant Man1a2 enzyme contributes to abnormal synthesis of proteins essential for lung development. The associated unfolded protein, hypoxic and oxidative stress responses can be mitigated with NAC. Comparisons with the developing human fetal lung transcriptome show that NAC likely restores normal vascular and epithelial tube morphogenesis in Man1a2 mutant mice.

CONCLUSION

Survival and lung ciliation in the Man1a2 mutant mouse, and its improvement with N-Acetyl cysteine is genotype-dependent. NAC-mediated rescue depends on the central role for oxidative and hypoxic stress in regulating ciliary function and organogenesis during development.

NAC blocks Cystatin C amyloid complex aggregation in a cell system and in skin of HCCAA patients

Hereditary cystatin C amyloid angiopathy is a dominantly inherited disease caused by a leucine to glutamine variant of human cystatin C (hCC). L68Q-hCC forms amyloid deposits in brain arteries associated with micro-infarcts, leading ultimately to paralysis, dementia and death in young adults. To evaluate the ability of molecules to interfere with aggregation of hCC while informing about cellular toxicity, we generated cells that produce and secrete WT and L68Q-hCC and have detected high-molecular weight complexes formed from the mutant protein. Incubations of either lysate or supernatant containing L68Q-hCC with reducing agents glutathione or N-acetyl-cysteine (NAC) breaks oligomers into monomers. Six L68Q-hCC carriers taking NAC had skin biopsies obtained to determine if hCC deposits were reduced following NAC treatment. Remarkably, ~50–90% reduction of L68Q-hCC staining was observed in five of the treated carriers suggesting that L68Q-hCC is a clinical target for reducing agents.

HCCAA is a dominantly inherited disease which causes brain hemorrhages as a result of mutant cystatin C aggregation in carriers. Here, the authors show that n- acetyl cysteine can prevent aggregation of mutant protein in a cell model system and reverse protein deposition in the skin of mutation-carrying subjects.

Oxidative Stress in ESRD Patients on Dialysis and the Risk of Cardiovascular Diseases

Chronic kidney disease is highly prevalent worldwide. The decline of renal function is associated with inadequate removal of a variety of uremic toxins that exert detrimental effects on cells functioning, thus affecting the cardiovascular system. The occurrence of cardiovascular aberrations in CKD is related to the impact of traditional risk factors and non-traditional CKD-associated risk factors, including anemia; inflammation; oxidative stress; the presence of some uremic toxins; and factors related to the type, frequency of dialysis and the composition of dialysis fluid. Cardiovascular diseases are the most frequent cause for the deaths of patients with all stages of renal failure. The kidney is one of the vital sources of antioxidant enzymes, therefore, the impairment of this organ is associated with decreased levels of these enzymes as well as increased levels of pro-oxidants. Uremic toxins have been shown to play a vital role in the onset of oxidative stress. Hemodialysis itself also enhances oxidative stress. Elevated oxidative stress has been demonstrated to be strictly related to kidney and cardiac damage as it aggravates kidney dysfunction and induces cardiac hypertrophy. Antioxidant therapies may prove to be beneficial since they can decrease oxidative stress, reduce uremic cardiovascular toxicity and improve survival.

Management of cardiovascular disease in patients with systemic lupus erythematosus

INTRODUCTION

SLE is increasingly recognized as an important risk factor for cardiovascular disease. Premature CAD and several other cardiac manifestations are resulting in significant morbidity and premature death among young and older adults. There is a considerable unmet need for developing specific guidelines toward the primary and secondary prevention of cardiovascular disease in SLE patients.

AREAS COVERED

The authors describe the prevalence of various cardiovascular manifestations, associated with traditional and lupus-specific risk factors. They summarize the evidence behind various nonpharmacological and pharmacological options such as cardiac medications, antimalarials, anti-inflammatory, and immunosuppressant medications.

EXPERT OPINION

There is considerable literature claiming that the traditional Framingham score used to calculate the risk in the general population would not clearly predict the 10-year risk among SLE patients as they do not include lupus-specific risk factors such as accelerated inflammation, immunometabolic changes, thrombosis, vasospasm, vasculitis, and endothelial dysfunction into account. Identifying potential risk factors among SLE patients and treating hyperlipidemia regardless of their risk scores may be the first step in reducing mortality. Blocking lupus-specific inflammatory pathways by targeting validated biomarkers of pathogenesis has great future potential and more studies are needed on their cardiovascular benefits.

Revisiting pharmacology of oxidative stress and endothelial dysfunction in cardiovascular disease: Evidence for redox-based therapies

According to the latest Global Burden of Disease Study data, non-communicable diseases in general and cardiovascular disease (CVD) in particular are the leading cause of premature death and reduced quality of life. Demographic shifts, unhealthy lifestyles and a higher burden of adverse environmental factors provide an explanation for these findings. The expected growing prevalence of CVD requires enhanced research efforts for identification and characterisation of novel therapeutic targets and strategies. Cardiovascular risk factors including classical (e.g. hypertension, diabetes, hypercholesterolaemia) and non-classical (e.g. environmental stress) factors induce the development of endothelial dysfunction, which is closely associated with oxidant stress and vascular inflammation and results in CVD, particularly in older adults. Most classically successful therapies for CVD display vasoprotective, antioxidant and anti-inflammatory effects, but were originally designed with other therapeutic aims. So far, only a few 'redox drugs' are in clinical use and many antioxidant strategies have not met expectations. With the present review, we summarise the actual knowledge on CVD pathomechanisms, with special emphasis on endothelial dysfunction, adverse redox signalling and oxidative stress, highlighting the preclinical and clinical evidence. In addition, we provide a brief overview of established CVD therapies and their relation to endothelial dysfunction and oxidative stress. Finally, we discuss novel strategies for redox-based CVD therapies trying to explain why, despite a clear link between endothelial dysfunction and adverse redox signalling and oxidative stress, redox- and oxidative stress-based therapies have not yet provided a breakthrough in the treatment of endothelial dysfunction and CVD.

N-Acetylcysteine Does Not Improve the Endothelial and Smooth Muscle Function in the Human Saphenous Vein

Oxidative stress can lead to vein graft dysfunction in the saphenous vein. This ex vivo study is aimed to compare the effects of increasing concentrations of the antioxidant N-acetylcysteine (NAC) with heparinized saline (HS) on endothelial and smooth muscle function in the human saphenous vein. Long saphenous vein segment obtained during infrainguinal bypass surgery was divided into 7 rings; 1 immersed in HS and the remaining 6 in increasing NAC concentrations (0.0025%, 0.005%, 0.01%, 0.02%, 0.03%, and 0.04%). Rings were mounted in an organ bath, and relaxant responses to acetylcholine and sodium nitroprusside were assessed through isometric tension studies. Endothelium-dependent relaxations were observed in 77 vein segments from 11 patients. No significant difference was seen in veins treated with either lower NAC concentrations (0.0025%, 0.005%, 0.01%, 0.02%, and 0.03%) or HS. However, HS-treated veins showed significantly better relaxation compared to those treated with maximum (0.04%) NAC ( P < .05). Endothelium-independent relaxations were observed in 91 segments from 13 patients. No difference in relaxation was observed between veins treated with HS or any of the NAC concentrations. In conclusion, lower NAC concentrations do not offer better endothelial protection than HS, whereas the highest NAC concentration has a detrimental effect on endothelium-dependent relaxation. Moreover, NAC did not show beneficial effect on direct smooth muscle relaxation.

Modulators of platelet function in aging

Platelets are small, anucleated effector cells that play an important role in linking the hemostatic and inflammatory processes in the body. Platelet function is known to be altered under various inflammatory conditions including aging. A gain in platelet function during aging can increase the risk of thrombotic events, such as stroke and acute myocardial infarction. Anti-platelet therapy is designed to reduce risk of serious cerebrovascular and cardiovascular events, but the adverse consequences of therapy, such as risk for bleeding increases with aging as well. Age-associated comorbidities such as obesity, diabetes, and hyperlipidemia also contribute to increased platelet activity and thus can enhance the risk of thrombosis. Therefore, identification of unique mechanisms of platelet dysfunction in aging and in age-associated comorbidities is warranted to design novel antiplatelet drugs. This review outlines some of the current areas of research on aging-related mechanisms of platelet hyperactivity and addresses the clinical urgency for designing anti-platelet therapies toward novel molecular targets in the aging population.

Cysteine/Glutathione Deficiency: A Significant and Treatable Corollary of Disease

Glutathione (GSH) deficiency may play a pivotal role in a variety of apparently unrelated clinical conditions and diseases. Orally administered N-acetylcysteine (NAC), which replenishes the cysteine required for GSH synthesis, has been tested in a large number of randomized placebo-controlled trials involving these diseases and conditions. This chapter focused on developing a base of evidence suggesting that NAC administration improves disease by increasing cysteine and/or GSH in a variety of diseases, thereby implying a significant role for GSH deficiency in the clinical basis of many diseases. To develop this base of evidence, we systematically selected studies which considered the hypothesis that the therapeutic efficacy for NAC is an indication that cysteine and/or GSH deficiency is a pathophysiological part of the diseases studied. In this manner we focus this chapter on explaining the biological mechanisms of NAC therapy in a wide variety of disorders and demonstrate its ubiquitous role in improving disease that involves disrupted GSH and/or cysteine metabolism.

Protection from Reperfusion Injury with Intracoronary N-Acetylcysteine in Patients with STEMI Undergoing Primary Percutaneous Coronary Intervention in a Cardiac Tertiary Center

BACKGROUND

Evidence suggests that oxidative stress plays a principal role in myocardial damage following ischemia/reperfusion events. Recent studies have shown that the antioxidant properties of N-acetylcysteine (NAC) may have cardioprotective effects in high doses, but-to the best of our knowledge-few studies have assessed this.

OBJECTIVES

Our objective was to investigate the impact of high-dose NAC on ischemia/reperfusion injury.

METHODS

We conducted a randomized double-blind placebo-controlled trial in which 100 consecutive patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention (PCI) were randomly assigned to the case group (high-dose NAC 100 mg/kg bolus followed by intracoronary NAC 480 mg during PCI then intravenous NAC 10 mg/kg for 12 h) or the control group (5% dextrose). We measured differences in peak creatine kinase-myocardial band (CK-MB) concentration, highly sensitive troponin T (hs-TnT), thrombolysis in myocardial infarction (TIMI) flow, myocardial blush grade (MBG), and corrected thrombolysis in myocardial infarction frame count (cTFC).

RESULTS

The peak CK-MB level was comparable between the two groups (P = 0.327), but patients receiving high-dose NAC demonstrated a significantly larger reduction in hs-TnT (P = 0.02). In total, 94% of the NAC group achieved TIMI flow grade 3 versus 80% of the control group (P = 0.03). No significant differences were observed between the two groups in terms of changes in the cTFC and MBG.

CONCLUSIONS

In this study, NAC improved myocardial reperfusion markers and coronary blood flow, as revealed by differences in peak hs-TnT and TIMI flow grade 3 levels, respectively. Further studies with large samples are warranted to elucidate the role of NAC in this population. ClinicalTrials.gov identifier: NCT01741207, and the Iranian Registry of Clinical Trials (IRCT; http://irct.ir ) registration number: IRCT201301048698N8.

Prevention of Contrast Nephropathy in Critically Ill Patients Using Acetylcysteine and Theophylline

Compared with periprocedural hydration alone, acetylcysteine with hydration significantly reduces the risk of contrast nephropathy in patients with chronic renal insufficiency by 50%. For elective contrast procedures, acetylcysteine should be given in a dose of 600 mg twice daily the day before and on the procedure day. For emergency procedures, a high dose intravenous regimen (150 mg/kg in 500 mL normal saline over 30 minutes immediately before contrast followed by 50 mg/kg in 500 mL normal saline over 4h) is effective. Given the low cost and good side-effect profile of acetylcysteine, it would seem prudent to give this drug with intravenous fluids to all critically ill patients scheduled for intravenous or intraarterial contrast procedures. Theophylline in a dose of 200 mg or 2.5 mg/kg IV 30 minutes before contrast may be an effective alternative for emergency procedures. Although its benefit compared with periprocedural hydration alone seems less well established, theophylline is a particularly attractive option for emergency procedures.

Peripheral artery disease, redox signaling, oxidative stress - Basic and clinical aspects

Reactive oxygen and nitrogen species (ROS and RNS, e.g. H2O2, nitric oxide) confer redox regulation of essential cellular signaling pathways such as cell differentiation, proliferation, migration and apoptosis. At higher concentrations, ROS and RNS lead to oxidative stress and oxidative damage of biomolecules (e.g. via formation of peroxynitrite, fenton chemistry). Peripheral artery disease (PAD) is characterized by severe ischemic conditions in the periphery leading to intermittent claudication and critical limb ischemia (end stage). It is well known that redox biology and oxidative stress play an important role in this setting. We here discuss the major pathways of oxidative stress and redox signaling underlying the disease progression with special emphasis on the contribution of inflammatory processes. We also highlight therapeutic strategies comprising pharmacological (e.g. statins, angiotensin-converting enzyme inhibitors, phosphodiesterase inhibition) and non-pharmacological (e.g. exercise) interventions. Both of these strategies induce potent indirect antioxidant and anti-inflammatory mechanisms that may contribute to an improvement of PAD associated complications and disease progression by removing excess formation of ROS and RNS (e.g. by ameliorating primary complications such as hyperlipidemia and hypertension) as well as the normalization of the inflammatory phenotype suppressing the progression of atherosclerosis.

Oral N-acetylcysteine and exercise tolerance in mild chronic obstructive pulmonary disease

Heightened oxidative stress is implicated in the progressive impairment of skeletal muscle vascular and mitochondrial function in chronic obstructive pulmonary disease (COPD). Whether accumulation of reactive oxygen species contributes to exercise intolerance in the early stages of COPD is unknown. The purpose of the present study was to determine the effects of oral antioxidant treatment with N-acetylcysteine (NAC) on respiratory, cardiovascular, and locomotor muscle function and exercise tolerance in patients with mild COPD. Thirteen patients [forced expiratory volume in 1 s (FEV₁)-to-forced vital capacity ratio < lower limit of normal (LLN) and FEV₁ ≥ LLN) were enrolled in a double-blind, randomized crossover study to receive NAC (1,800 mg/day) or placebo for 4 days. Severe-intensity constant-load exercise tests were performed with noninvasive measurements of central hemodynamics (stroke volume, heart rate, and cardiac output via impedance cardiography), arterial blood pressure, pulmonary ventilation and gas exchange, quadriceps muscle oxygenation (near-infrared spectroscopy), and estimated capillary blood flow. Nine patients completed the study with no major adverse clinical effects. Although NAC elevated plasma glutathione by ~27% compared with placebo (P < 0.05), there were no differences in exercise tolerance (placebo: 325 ± 47 s, NAC: 336 ± 51 s), central hemodynamics, arterial blood pressure, pulmonary ventilation or gas exchange, locomotor muscle oxygenation, or capillary blood flow from rest to exercise between conditions (P > 0.05 for all). In conclusion, modulation of plasma redox status with oral NAC treatment was not translated into beneficial effects on central or peripheral components of the oxygen transport pathway, thereby failing to improve exercise tolerance in nonhypoxemic patients with mild COPD.NEW & NOTEWORTHY Acute antioxidant treatment with N-acetylcysteine (NAC) elevated plasma glutathione but did not modulate central or peripheral components of the O₂ transport pathway, thereby failing to improve exercise tolerance in patients with mild chronic obstructive pulmonary disease (COPD).

Efficacy of Atorvastatin in Prevention of Contrast-induced Nephropathy in High-risk Patients Undergoing Angiography: A Double-blind Randomized Controlled Trial

Objective:

To evaluate the efficacy and safety of atorvastatin (ATN) 80 mg in the prevention of contrast medium- induced nephropathy (CIN) in high risk patients undergoing angiograph.

Materials and Methods:

This was a prospective, double-blind, two-arm, parallel group RCT. A total of 216 patients undergoing coronary angiography were screened, and 188 eligible patients were randomized to two treatment arms. Patients in Group A received tablet N-acetylcysteine (NAC) 1200 mg once daily, and patients in Group B received tablet atorvastatin 80 mg + NAC 1200 mg once daily, for 3 days before, and 2 days after angiography.

Results:

A total of 160 patients completed the trial. Postprocedure, nine and two CIN cases were found in Group A and B, respectively. The mean change in serum creatinine was 0.086 ± 0.168 in Group A and 0.021 ± 0.083 in Group B, which was statistically significant (P = 0.0289). Postprocedure, the estimated glomerular filteration rate was reduced by 19.52 in Group A and 13.55 in Group B (P = 0.003).

Conclusion:

This trial indicates the positive role of statins in preventive strategy against CIN along with NAC.

Exercise-induced heat stress disrupts the shear-dilatory relationship

NEW FINDINGS

What is the central question of this study? Although heat stress is known to increase cardiovascular strain, no study, to date, had explored the potential impact of exercise-induced heat stress on vascular function. What is the main finding and its importance? We found that acute exercise tended to reduce flow-mediated dilatation (FMD), owing in part to reduced reactive hyperaemia/shear stimulus; thus, when FMD is normalized to shear no postexercise deficit exists. Exercise-induced heat stress increased reactive hyperaemia, shear rate, coupled with a sustained FMD postexercise, suggests that exercise-induced heat stress increases the amount of shear stimulus to elicit a similar response, indicating reduced vascular responsiveness, or reserve, which might increase cardiovascular susceptibility. Heat stress increases cardiovascular strain and is of particular concern in occupations, such as firefighting, in which individuals are required to perform strenuous work while wearing personal protective equipment. Sudden cardiac events are associated with strenuous activity and are the leading cause of duty-related death among firefighters, accounting for ∼50% of duty-related fatalities per year. Understanding the acute effects of exercise-induced heat stress (EIHS) on vascular endothelial function may provide insight into the mechanisms precipitating acute coronary events in firefighters. The purpose of this study, therefore, was to determine the effects of EIHS on vascular endothelial function. Using a balanced crossover design, 12 healthy men performed 100 min of moderate-intensity, intermittent exercise with and without EIHS (personal protective equipment or cooling vest, respectively). Measurements of flow-mediated dilatation (FMD), reactive hyperaemia and shear rate area under the curve (SR_AUC ) were performed pre- and postexercise. During EIHS, core temperature was significantly higher (38 ± 0.1 versus 37 ± 0.1°C). Postexercise FMD tended to be suppressed in both conditions, but was not different from pre-exercise. Reactive hyperaemia was reduced after no-EIHS but increased after EIHS. Thus, normalizing FMD to the shear stimulus (FMD/SR_AUC ) revealed a significant reduction in FMD after EIHS only (pre-exercise 0.15 ± 0.04 and 0.13 ± 0.02 s^-1 versus postexercise, 0.13 ± 0.02 and 0.06 ± 0.02 s^-1 , no-EIHS and EIHS, respectively). We conclude that moderate heat stress superimposed on moderate-intensity exercise resulted in reduced vascular endothelial function. This heat stress-induced alteration in the shear-dilatory relationship may relate to the increased risk of acute coronary events associated with activities that combine physical exertion and heat stress (i.e. firefighting).

Time in Redox Adaptation Processes: From Evolution to Hormesis

Life on Earth has to adapt to the ever changing environment. For example, due to introduction of oxygen in the atmosphere, an antioxidant network evolved to cope with the exposure to oxygen. The adaptive mechanisms of the antioxidant network, specifically the glutathione (GSH) system, are reviewed with a special focus on the time. The quickest adaptive response to oxidative stress is direct enzyme modification, increasing the GSH levels or activating the GSH-dependent protective enzymes. After several hours, a hormetic response is seen at the transcriptional level by up-regulating Nrf2-mediated expression of enzymes involved in GSH synthesis. In the long run, adaptations occur at the epigenetic and genomic level; for example, the ability to synthesize GSH by phototrophic bacteria. Apparently, in an adaptive hormetic response not only the dose or the compound, but also time, should be considered. This is essential for targeted interventions aimed to prevent diseases by successfully coping with changes in the environment e.g., oxidative stress.

The Role of Mitochondrial Reactive Oxygen Species in Cardiovascular Injury and Protective Strategies

Ischaemia/reperfusion (I/R) injury of the heart represents a major health burden mainly associated with acute coronary syndromes. While timely coronary reperfusion has become the established routine therapy in patients with ST-elevation myocardial infarction, the restoration of blood flow into the previously ischaemic area is always accompanied by myocardial injury. The central mechanism involved in this phenomenon is represented by the excessive generation of reactive oxygen species (ROS). Besides their harmful role when highly generated during early reperfusion, minimal ROS formation during ischaemia and/or at reperfusion is critical for the redox signaling of cardioprotection. In the past decades, mitochondria have emerged as the major source of ROS as well as a critical target for cardioprotective strategies at reperfusion. Mitochondria dysfunction associated with I/R myocardial injury is further described and ultimately analyzed with respect to its role as source of both deleterious and beneficial ROS. Furthermore, the contribution of ROS in the highly investigated field of conditioning strategies is analyzed. In the end, the vascular sources of mitochondria-derived ROS are briefly reviewed.

Protective Effect of Antenatal Antioxidant on Nicotine-Induced Heart Ischemia-Sensitive Phenotype in Rat Offspring

Fetal nicotine exposure increased risk of developing cardiovascular disease later in life. The present study tested the hypothesis that perinatal nicotine-induced programming of heart ischemia-sensitive phenotype is mediated by enhanced reactive oxygen species (ROS) in offspring. Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps from day 4 of gestation to day 10 after birth, in the absence or presence of a ROS inhibitor, N-acetyl-cysteine (NAC) in drinking water. Experiments were conducted in 8 month old age male offspring. Isolated hearts were perfused in a Langendorff preparation. Perinatal nicotine treatment significantly increased ischemia and reperfusion-induced left ventricular injury, and decreased post-ischemic recovery of left ventricular function and coronary flow rate. In addition, nicotine enhanced cardiac ROS production and significantly attenuated protein kinase Cε (PKCε) protein abundance in the heart. Although nicotine had no effect on total cardiac glycogen synthase kinase-3β (GSK3β) protein expression, it significantly increased the phosphorylation of GSK3β at serine 9 residue in the heart. NAC inhibited nicotine-mediated increase in ROS production, recovered PKCε gene expression and abrogated increased phosphorylation of GSK3β. Of importance, NAC blocked perinatal nicotine-induced increase in ischemia and reperfusion injury in the heart. These findings provide novel evidence that increased oxidative stress plays a causal role in perinatal nicotine-induced developmental programming of ischemic sensitive phenotype in the heart, and suggest potential therapeutic targets of anti-oxidative stress in the treatment of ischemic heart disease.

Vascular endothelial dysfunction and pharmacological treatment

The endothelium exerts multiple actions involving regulation of vascular permeability and tone, coagulation and fibrinolysis, inflammatory and immunological reactions and cell growth. Alterations of one or more such actions may cause vascular endothelial dysfunction. Different risk factors such as hypercholesterolemia, homocystinemia, hyperglycemia, hypertension, smoking, inflammation, and aging contribute to the development of endothelial dysfunction. Mechanisms underlying endothelial dysfunction are multiple, including impaired endothelium-derived vasodilators, enhanced endothelium-derived vasoconstrictors, over production of reactive oxygen species and reactive nitrogen species, activation of inflammatory and immune reactions, and imbalance of coagulation and fibrinolysis. Endothelial dysfunction occurs in many cardiovascular diseases, which involves different mechanisms, depending on specific risk factors affecting the disease. Among these mechanisms, a reduction in nitric oxide (NO) bioavailability plays a central role in the development of endothelial dysfunction because NO exerts diverse physiological actions, including vasodilation, anti-inflammation, antiplatelet, antiproliferation and antimigration. Experimental and clinical studies have demonstrated that a variety of currently used or investigational drugs, such as angiotensin-converting enzyme inhibitors, angiotensin AT1 receptors blockers, angiotensin-(1-7), antioxidants, beta-blockers, calcium channel blockers, endothelial NO synthase enhancers, phosphodiesterase 5 inhibitors, sphingosine-1-phosphate and statins, exert endothelial protective effects. Due to the difference in mechanisms of action, these drugs need to be used according to specific mechanisms underlying endothelial dysfunction of the disease.

The role of antioxidants in the chemistry of oxidative stress: A review

This Review Article is focused on the action of the reactive oxygenated species in inducing oxidative injury of the lipid membrane components, as well as on the ability of antioxidants (of different structures and sources, and following different mechanisms of action) in fighting against oxidative stress. Oxidative stress is defined as an excessive production of reactive oxygenated species that cannot be counteracted by the action of antioxidants, but also as a perturbation of cell redox balance. Reactive oxygenated/nitrogenated species are represented by superoxide anion radical, hydroxyl, alkoxyl and lipid peroxyl radicals, nitric oxide and peroxynitrite. Oxidative stress determines structure modifications and function modulation in nucleic acids, lipids and proteins. Oxidative degradation of lipids yields malondialdehyde and 4-hydroxynonenal, but also isoprostanes, from unsaturated fatty acids. Protein damage may occur with thiol oxidation, carbonylation, side-chain oxidation, fragmentation, unfolding and misfolding, resulting activity loss. 8-hydroxydeoxyguanosine is an index of DNA damage. The involvement of the reactive oxygenated/nitrogenated species in disease occurrence is described. The unbalance between the oxidant species and the antioxidant defense system may trigger specific factors responsible for oxidative damage in the cell: over-expression of oncogene genes, generation of mutagen compounds, promotion of atherogenic activity, senile plaque occurrence or inflammation. This leads to cancer, neurodegeneration, cardiovascular diseases, diabetes, kidney diseases. The concept of antioxidant is defined, along with a discussion of the existent classification criteria: enzymatic and non-enzymatic, preventative or repair-systems, endogenous and exogenous, primary and secondary, hydrosoluble and liposoluble, natural or synthetic. Primary antioxidants are mainly chain breakers, able to scavenge radical species by hydrogen donation. Secondary antioxidants are singlet oxygen quenchers, peroxide decomposers, metal chelators, oxidative enzyme inhibitors or UV radiation absorbers. The specific mechanism of action of the most important representatives of each antioxidant class (endogenous and exogenous) in preventing or inhibiting particular factors leading to oxidative injury in the cell, is then reviewed. Mutual influences, including synergistic effects are presented and discussed. Prooxidative influences likely to occur, as for instance in the presence of transition metal ions, are also reminded.

Widespread endotheliopathy in adults with cyanotic congenital heart disease

INTRODUCTION

Cyanotic congenital heart disease is associated with functional limitation and vascular events. The nature and extent of endothelial dysfunction in cyanotic adults is poorly understood. We sought to characterise endothelial function in this setting.

METHODS

A total of fourteen adults with cyanotic congenital heart disease (40±3 years) together with age- and sex-matched healthy controls underwent assessment of nitric oxide-dependent vascular responses, including flow-mediated dilatation of the brachial artery and dynamic vessel analysis of the retina in response to flickering light. Plasma levels of the endothelium-derived vasoconstrictor endothelin-1 and the nitric oxide antagonist, asymmetric dimethylarginine, were measured. Circulating endothelial progenitor cells were assessed by flow cytometry.

RESULTS

Flow-mediated dilatation was significantly lower in cyanosed adults than controls (4.0±0.8 versus 7.2±1.0%, p=0.019, n=11 per group). Retinal arterial and venous dilatory responses were also impaired (2.9±0.8 versus 5.0±0.6%, p=0.05 and 3.4±0.3 versus 5.2±0.7%, p=0.04, n=13). Serum levels of endothelin-1 and asymmetric dimethylarginine were higher in cyanosed adults (3.0±0.6 versus 1.1±0.1 pg/ml, p=0.004 and 0.68±0.05 versus 0.52±0.02 μmol/L, p=0.03, n=11). Endothelial progenitor cells (CD34+CD45dimCD133+KDR+) were reduced in those with chronic cyanosis (17±4 versus 40±6 per million white blood cells, p=0.005, n=11).

CONCLUSIONS

Endothelial function is impaired in the systemic arteries and retinal vessels in adults with cyanotic congenital heart disease, suggesting a widespread endotheliopathy. Diminished numbers of endothelial progenitor cells might potentially contribute to these observations.

Gestational hypoxia increases reactive oxygen species and inhibits steroid hormone-mediated upregulation of Ca(2+)-activated K(+) channel function in uterine arteries

Gestational hypoxia inhibits steroid hormone-induced upregulation of Ca(2+)-activated K(+) (KCa) channel activities in uterine arteries. We tested the hypothesis that increased reactive oxygen species play an important role in hypoxia-mediated inhibition of KCa channel activities. Uterine arteries were isolated from nonpregnant (nonpregnant uterine artery) and near-term (≈142-145 day) pregnant (pregnant uterine artery) sheep maintained at either sea level or high altitude (3820 m, Pao2: 60 mm Hg) for 110 days. In pregnant uterine arteries, hypoxia significantly decreased large conductance channel opener NS1619- and small conductance channel opener NS309-induced relaxations, which were partially restored by reactive oxygen species inhibitor N-acetylcysteine (NAC). NAC significantly increased large conductance KCa but not small conductance KCa current densities in uterine arterial smooth muscle cells in pregnant animals acclimatized to high altitude. The NAC-sensitive component of small conductance KCa-induced relaxations was diminished in endothelium-denuded arteries. In nonpregnant uterine arteries, NS1619- and NS309-induced relaxations were diminished compared with those in pregnant uterine arteries. Treatment of nonpregnant uterine arteries with 17β-estradiol and progesterone for 48 hours increased small conductance KCa type 3 protein abundance and NS1619- and NS309-induced relaxations, which were inhibited by hypoxia. This hypoxia-mediated inhibition was reversed by NAC. Consistently, steroid hormone treatment had no significant effects on large conductance KCa current density in nonpregnant uterine arteries of hypoxic animals in the absence of NAC but significantly increased it in the presence of NAC. These results suggest an important role of hypoxia-mediated reactive oxygen species in negatively regulating steroid hormone-mediated upregulation of KCa channel activity and adaptation of uterine vascular reactivity in pregnancy, which may contribute to the increased incidence of preeclampsia and fetal intrauterine growth restriction associated with gestational hypoxia.

N-acetylcysteine (NAC) in neurological disorders: mechanisms of action and therapeutic opportunities

BACKGROUND

There is an expanding field of research investigating the benefits of medicines with multiple mechanisms of action across neurological disorders. N-acetylcysteine (NAC), widely known as an antidote to acetaminophen overdose, is now emerging as treatment of vascular and nonvascular neurological disorders. NAC as a precursor to the antioxidant glutathione modulates glutamatergic, neurotrophic, and inflammatory pathways.

AIM AND DISCUSSION

Most NAC studies up to date have been carried out in animal models of various neurological disorders with only a few studies completed in humans. In psychiatry, NAC has been tested in over 20 clinical trials as an adjunctive treatment; however, this topic is beyond the scope of this review. Herein, we discuss NAC molecular, intracellular, and systemic effects, focusing on its potential applications in neurodegenerative diseases including spinocerebellar ataxia, Parkinson's disease, tardive dyskinesia, myoclonus epilepsy of the Unverricht-Lundbor type as well as multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer's disease.

CONCLUSION

Finally, we review the potential applications of NAC to facilitate recovery after traumatic brain injury, cerebral ischemia, and in treatment of cerebrovascular vasospasm after subarachnoid hemorrhage.

Oxidative stress and nucleic acid oxidation in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have high cardiovascular mortality and morbidity and a high risk for developing malignancy. Excessive oxidative stress is thought to play a major role in elevating these risks by increasing oxidative nucleic acid damage. Oxidative stress results from an imbalance between reactive oxygen/nitrogen species (RONS) production and antioxidant defense mechanisms and can cause vascular and tissue injuries as well as nucleic acid damage in CKD patients. The increased production of RONS, impaired nonenzymatic or enzymatic antioxidant defense mechanisms, and other risk factors including gene polymorphisms, uremic toxins (indoxyl sulfate), deficiency of arylesterase/paraoxonase, hyperhomocysteinemia, dialysis-associated membrane bioincompatibility, and endotoxin in patients with CKD can inhibit normal cell function by damaging cell lipids, arachidonic acid derivatives, carbohydrates, proteins, amino acids, and nucleic acids. Several clinical biomarkers and techniques have been used to detect the antioxidant status and oxidative stress/oxidative nucleic acid damage associated with long-term complications such as inflammation, atherosclerosis, amyloidosis, and malignancy in CKD patients. Antioxidant therapies have been studied to reduce the oxidative stress and nucleic acid oxidation in patients with CKD, including alpha-tocopherol, N-acetylcysteine, ascorbic acid, glutathione, folic acid, bardoxolone methyl, angiotensin-converting enzyme inhibitor, and providing better dialysis strategies. This paper provides an overview of radical production, antioxidant defence, pathogenesis and biomarkers of oxidative stress in patients with CKD, and possible antioxidant therapies.

Mitochondria and endothelial function

In contrast to their role in cell types with higher energy demands, mitochondria in endothelial cells primarily function in signaling cellular responses to environmental cues. This article provides an overview of key aspects of mitochondrial biology in endothelial cells, including subcellular location, biogenesis, dynamics, autophagy, reactive oxygen species production and signaling, calcium homeostasis, regulated cell death, and heme biosynthesis. In each section, we introduce key concepts and then review studies showing the importance of that mechanism to endothelial control of vasomotor tone, angiogenesis, and/or inflammatory activation. We particularly highlight the small number of clinical and translational studies that have investigated each mechanism in human subjects. Finally, we review interventions that target different aspects of mitochondrial function and their effects on endothelial function. The ultimate goal of such research is the identification of new approaches for therapy. The reviewed studies make it clear that mitochondria are important in endothelial physiology and pathophysiology. A great deal of work will be needed, however, before mitochondria-directed therapies are available for the prevention and treatment of cardiovascular disease.

The antihypertensive effect of cysteine

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease and kidney failure. Essential hypertension results from a combination of genetic and lifestyle factors. One such lifestyle factor is diet, and its role in the control of blood pressure has come under much scrutiny. Just as increased salt and sugar are known to elevate blood pressure, other dietary factors may have antihypertensive effects. Studies including the Optimal Macronutrient Intake to Prevent Heart Disease (OmniHeart) study, Multiple Risk Factor Intervention Trial (MRFIT), International Study of Salt and Blood Pressure (INTERSALT) and Dietary Approaches to Stop Hypertension (DASH) study have demonstrated an inverse relationship between dietary protein and blood pressure. One component of dietary protein that may partially account for its antihypertensive effect is the nonessential amino acid cysteine. Studies in hypertensive humans and animal models of hypertension have shown that N-acetylcysteine, a stable cysteine analogue, lowers blood pressure, which substantiates this idea. Cysteine may exert its antihypertensive effects directly or through its storage form, glutathione, by decreasing oxidative stress, improving insulin resistance and glucose metabolism, lowering advanced glycation end products, and modulating levels of nitric oxide and other vasoactive molecules. Therefore, adopting a balanced diet containing cysteine-rich proteins may be a beneficial lifestyle choice for individuals with hypertension. An example of such a diet is the DASH diet, which is low in salt and saturated fat; includes whole grains, poultry, fish and nuts; and is rich in vegetables, fruits and low-fat dairy products.

Effects of N-acetyl-cysteine on endothelial function and inflammation in patients with type 2 diabetes mellitus

Endothelial dysfunction has been associated with premature vascular disease. There is increasing data that N-acetyl-cysteine (NAC) may prevent or improve endothelial dysfunction. The aim of this study was to assess the effects of NAC on endothelial function in patients with type 2 diabetes mellitus, a population at high risk for endothelial dysfunction. Twenty-four patients with diabetes mellitus were assigned randomly to initial therapy with either 900 mg NAC or placebo twice daily in a double-blind, cross-over study design. Flowmediated vasodilation (FMD) of the brachial artery was assessed at baseline, after four weeks of therapy, after a four-week wash-out period, and after another four weeks on the opposite treatment. Plasma and red blood cell glutathione levels and high-sensitivity C-reactive protein (CRP) were measured at all four visits. At baseline, FMD was moderately impaired (3.7±2.9%). There was no significant change in FMD after four weeks of NAC therapy as compared to placebo (0.1±3.6% vs. 1.2±4.2%). Similarly, there was no significant change in glutathione levels. However, median CRP decreased from 2.35 to 2.14 mg/L during NAC therapy (p=0.04), while it increased from 2.24 to 2.65 mg/L with placebo. No side effects were noted during the treatment period. In this double-blind, randomized cross-over study, four weeks of oral NAC therapy failed to improve endothelial dysfunction in patients with diabetes mellitus. However, NAC therapy decreased CRP levels, suggesting that this compound may have some efficacy in reducing systemic inflammation.

The role of plasma aminothiols in the prediction of coronary microvascular dysfunction and plaque vulnerability

BACKGROUND

Although oxidative stress is considered a key pathogenic step in mediating vascular dysfunction and atherosclerosis development, their association has not been evaluated in human coronary circulation in vivo. Accordingly, we hypothesized that higher oxidative stress would be associated with abnormal coronary epicardial structure and microvascular function.

METHODS

We measured coronary flow velocity reserve (CFVR) and hyperemic microvascular resistance (HMR) as indices of microvascular function, and epicardial plaque volume and necrotic core using intravascular ultrasound (IVUS) in 47 patients undergoing cardiac catheterization. Plasma glutathione, cystine and their ratio served as measures of oxidative stress while high-sensitivity C-reactive protein (hs-CRP) served as a measure of inflammation.

RESULTS

Lower glutathione, a measure of increased oxidative stress was associated with impaired microvascular function [CFVR (r=0.39, p=0.01) and HMR (r=-0.43, p=0.004)], greater plaque burden (r=-0.32, p=0.03) and necrotic core (r=-0.39, p=0.008). Similarly, higher cystine/glutathione ratio was associated with impaired microvascular function [CFVR (r=-0.29, p=0.04)] and greater necrotic core (r=0.37, p=0.01). In comparison, higher hs-CRP was associated only with greater necrotic core (r=0.45, p=0.003). After multivariate adjustment for age, gender, hypertension, diabetes, acute coronary syndrome presentation, body mass index, tobacco abuse, statin use and hs-CRP, glutathione remained an independent predictor of CFVR, HMR and necrotic core (p<0.05).

CONCLUSIONS

Lower plasma glutathione level a measure of increased oxidative stress, was an independent predictor of impaired coronary microvascular function and plaque necrotic core.

Chronic Treatment With N-acetylcysteine Improves Cardiac Function but Does Not Prevent Progression of Cardiomyopathy in Syrian Cardiomyopathic Hamsters

Oxidative stress has been postulated to contribute to the onset and development of heart failure (HF). The efficacy of antioxidant therapy in HF, however, remains controversial. This study evaluates the effect of the antioxidant N-acetylcysteine (NAC, 1 g/kg per day) on cardiovascular function in 2- and 6-month-old Bio-TO2 Syrian cardiomyopathic hamsters (SCH) after treatment for 1 month and 5 months with this drug. Endothelial function, systolic blood pressure (SBP), and echocardiographic parameters were evaluated. Age-matched F1-B golden hamsters were used as controls. One month of NAC administration significantly decreased SBP in 2-month-old SCH (n = 5, P < 0.001) without modifying echocardiographic values. Five-month treatment of cardiomyopathic animals with the antioxidant improved the acetylcholine-induced relaxation in aortic rings by 24% (E Max value from 45.8% ± 4% to 55.3% ± 2% n = 7, P < .05) but did not modify EC50 values for the acetylcholine concentration-response curve. In addition, 5-month administration of NAC to SCH increased ejection fraction from 39% ± 4% to 57% ± 4% (n = 11, P < .001) and decreased left ventricular end-diastolic and end-systolic volumes (from 0.38 ± 0.04 mL/100 g body weight (BW) and 0.22 ± 0.03 mL/100 g BW, before, to 0.24 ± 0.04 mL/100 g BW and 0.12 ± 0.03 mL/100 g BW after treatment, P < .01). Cardiac output index also improved after 5 months of treatment, although it did not reach statistical significance. These results suggest that antioxidant therapy alone decreases ventricular dilatation and improves cardiovascular function in this animal model of dilated cardiomyopathy, but it does not prevent the appearance of HF.

N-acetylcysteine-enhanced contrast provides cardiorenal protection

OBJECTIVES

We sought to evaluate the cardiac and renal effects of an N-acetylcysteine (NAC)-enhanced intracoronary radiographic contrast agent.

BACKGROUND

Recent studies suggest that high-dose NAC provides better protection from contrast-induced nephropathy, and the antioxidant properties of NAC may also provide cardiac protection. The use of angiographic contrast agents as a drug delivery vehicle for cardiorenal protection effects has not been investigated.

METHODS

In a pig model of prolonged cardiac ischemia-reperfusion, NAC-enhanced contrast medium was tested and compared with iopamidol contrast only. Myocardium and renal function were assessed after 24 h.

RESULTS

There was no significant difference in the area-at-risk for myocardial infarction (MI) between contrast only and NAC-enhanced contrast medium. In contrast, MI size was about 40% smaller in NAC-enhanced contrast medium-treated animals. These findings were associated with a significant difference in MI morphology. MIs in the NAC-enhanced contrast medium group had a mottled appearance, whereas in the contrast only group they were homogeneous and had a discrete border zone. These differences could explain a higher incidence of periprocedural ventricular arrhythmias in the NAC-enhanced contrast medium group. Histopathological analysis of the myocardium revealed a reduction in programmed cell death by NAC-enhanced contrast medium that may explain the increase in ischemia tolerance. Last, NAC-enhanced contrast medium administration blunted the rise in serum creatinine levels by about 60% and protected from renotubular apotosis.

CONCLUSIONS

NAC-enhanced contrast medium reduces MI size and protects renal function in a pig model of ischemia and reperfusion.

Amikacin-Induced Nephropathy: Is There Any Protective Way?

Amikacin is a commonly used antibacterial drug that can cause significant nephrotoxic effects in both humans and experimental animals. It has been reported that one mechanism of the toxic effects of aminoglycoside antibiotics are the result of oxidative reactions. The aim of this study is to examine the effects of N-acetylcysteine, a thiol-containing antioxidant, on renal function (serum creatinine) and morphology (renal tubular damage) in mice subjected to amikacin-induced nephrotoxicity. A total of 32 mice were equally divided into four groups that were injected with either saline, amikacin (1.2 g/kg intraperitoneally), N-acetylcysteine (150 mg/kg intraperitoneally for three days) plus amikacin (1.2 g/kg intraperitoneally on the third day as a single dose), or N-acetylcysteine (150 mg/kg intraperitoneally). Amikacin administration led to granulovacuolar tubular degeneration in light microscopic examination and myeloid bodies, mitochondrial electron-dense material deposition, and mitochondrial swelling in the proximal tubule epithelium in the electron microscopic evaluation. N-acetylcysteine administration before amikacin injection caused significant decreases in myeloid body and mitochondrial swelling and granulovacuolar tubular degeneration formation. Serum creatinine levels did not change as a result of any treatment. The results show that N-acetylcysteine has a protective effect on nephrotoxicity induced by amikacin. Higher doses of amikacin should be tried to observe biochemical effects.

Glutathione, vitamin E and oxidative stress in coronary artery disease: relevance of age and gender

BACKGROUND

Observational studies suggest that low levels of antioxidants are associated with high risk for coronary artery disease (CAD). We investigated whether the biomarkers of oxidative balance undergo the same modifications in all CAD patient groups, regardless of gender and age.

MATERIALS AND METHODS

One hundred sixty-eight CAD patients and 107 healthy controls were assayed for plasma levels of reduced glutathione (GSH), alpha- and gamma-tocopherol (alpha- and gamma-T) as endogenous antioxidants. A damage score (DS), representative of oxidative stress status, was calculated. ANCOVA models were used to test the association between antioxidants, DS and CAD and its modulation by age and gender.

RESULTS

The DS was higher in CAD than in controls. GSH levels, were lower in CAD patients (mean +/- SEM: 57.61 +/- 1.87 micromol 10 g(-1) haemoglobin vs. 68.55 +/- 2.23 in controls, P < 0.0006) in males and in older subjects. Levels of other antioxidants exhibited a complex pattern. Overall, no difference was found in alpha- and gamma-T contents between CAD and controls, but lower alpha-T values were observed in CAD females. A significant interaction between CAD status and gender was observed (P = 0.003).

CONCLUSIONS

Our study shows that the involvement of antioxidants in CAD is related to patients' characteristics. These findings may be relevant in planning antioxidant therapies.