Effect of intravenous N-acetylcysteine on outcomes after coronary artery bypass surgery: A randomized, double-blind, placebo-controlled clinical trial

Serpina3k lactylation protects from cardiac ischemia reperfusion injury

Lactate produced during ischemia-reperfusion injury is known to promote lactylation of proteins, which play controversial roles. By analyzing the lactylomes and proteomes of mouse myocardium during ischemia-reperfusion injury using mass spectrometry, we show that both Serpina3k protein expression and its lactylation at lysine 351 are increased upon reperfusion. Both Serpina3k and its human homolog, SERPINA3, are abundantly expressed in cardiac fibroblasts, but not  in cardiomyocytes. Biochemically, lactylation of Serpina3k enhances protein stability. Using Serpina3k knockout mice and mice overexpressing its lactylation-deficient mutant, we find that Serpina3k protects from cardiac injury in a lysine 351 lactylation-dependent manner. Mechanistically, ischemia-reperfusion-stimulated fibroblasts secrete Serpina3k/SERPINA3, and protect cardiomyocytes from reperfusion-induced apoptosis in a paracrine fashion, partially through the activation of cardioprotective reperfusion injury salvage kinase and survivor activating factor enhancement pathways. Our results demonstrate the pivotal role of protein lactylation in cardiac ischemia-reperfusion injury, which may hold therapeutic value.

Systematic review and meta-analysis of the effect of N-acetylcysteine on outcomes after liver resection

BACKGROUND

N-Acetylcysteine (NAC) is a recognized antioxidative agent that facilitates the conjugation of toxic metabolites. In recent years, NAC has been routinely used to limit ischaemia-reperfusion injury in liver transplantation. There remains, however, contradictory evidence on its effectiveness in liver resection. This meta-analysis examines the effectiveness of NAC in improving outcomes following hepatectomy.

METHODS

A comprehensive search of the MEDLINE, EMBASE, and Cochrane databases was performed to identify relevant randomized controlled trials (RCTs) published since database inception until November 2023. The outcomes of Day 1 biochemical markers (lactate, ALT, bilirubin, and INR), length of stay, transfusion rates, and morbidity were extracted. Quantitative pooling of data was based on a random-effects model. The study protocol was registered on PROSPERO (Registration no: CRD42023442429).

RESULTS

Five RCTs reporting on 388 patients undergoing hepatectomy were included in the analysis. There were no significant differences in patient demographics between groups. Post-operative lactate was lower in patients receiving NAC (WMD -0.61, 95% CI -1.19 to -0.04, I2 = 67%). There were, however, no differences in the post-operative INR (WMD -0.04, 95% CI -0.19 to 0.12, I2 = 96%) and ALT (WMD -94.94, 95% CI -228.46 to 40.38; I2 = 67%). More importantly, there were no statistically significant differences in length of stay, transfusion rates, and morbidity between the two groups.

CONCLUSION

The administration of NAC in liver resection did not alter important biochemical parameters suggesting any real effectiveness in reducing hepatic dysfunction. There were no improvements in the clinical outcomes of length of stay, transfusion rates, and overall morbidity.

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

Effects of interventions targeting the systemic inflammatory response to cardiac surgery on clinical outcomes in adults

BACKGROUND

Organ injury is a common and severe complication of cardiac surgery that contributes to the majority of deaths. There are no effective treatment or prevention strategies. It has been suggested that innate immune system activation may have a causal role in organ injury. A wide range of organ protection interventions targeting the innate immune response have been evaluated in randomised controlled trials (RCTs) in adult cardiac surgery patients, with inconsistent results in terms of effectiveness.

OBJECTIVES

The aim of the review was to summarise the results of RCTs of organ protection interventions targeting the innate immune response in adult cardiac surgery. The review considered whether the interventions had a treatment effect on inflammation, important clinical outcomes, or both.

SEARCH METHODS

CENTRAL, MEDLINE, Embase, conference proceedings and two trial registers were searched on October 2022 together with reference checking to identify additional studies.

SELECTION CRITERIA

RCTs comparing organ protection interventions targeting the innate immune response versus placebo or no treatment in adult patients undergoing cardiac surgery where the treatment effect on innate immune activation and on clinical outcomes of interest were reported.

DATA COLLECTION AND ANALYSIS

Searches, study selection, quality assessment, and data extractions were performed independently by pairs of authors. The primary inflammation outcomes were peak IL-6 and IL-8 concentrations in blood post-surgery. The primary clinical outcome was in-hospital or 30-day mortality. Treatment effects were expressed as risk ratios (RR) and standardised mean difference (SMD) with 95% confidence intervals (CI). Meta-analyses were performed using random effects models, and heterogeneity was assessed using I2.

MAIN RESULTS

A total of 40,255 participants from 328 RCTs were included in the synthesis. The effects of treatments on IL-6 (SMD -0.77, 95% CI -0.97 to -0.58, I2 = 92%) and IL-8 (SMD -0.92, 95% CI -1.20 to -0.65, I2 = 91%) were unclear due to heterogeneity. Heterogeneity for inflammation outcomes persisted across multiple sensitivity and moderator analyses. The pooled treatment effect for in-hospital or 30-day mortality was RR 0.78, 95% CI 0.68 to 0.91, I2 = 0%, suggesting a significant clinical benefit. There was little or no treatment effect on mortality when analyses were restricted to studies at low risk of bias. Post hoc analyses failed to demonstrate consistent treatment effects on inflammation and clinical outcomes. Levels of certainty for pooled treatment effects on the primary outcomes were very low.

AUTHORS' CONCLUSIONS

A systematic review of RCTs of organ protection interventions targeting innate immune system activation did not resolve uncertainty as to the effectiveness of these treatments, or the role of innate immunity in organ injury following cardiac surgery.

Comparing the efficacy of N-acetylcysteine plus carvedilol versus carvedilol in the prevention of atrial fibrillation following coronary artery bypass graft surgery

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia following open-heart surgery. Agents with antioxidant properties may reduce postoperative complications like postoperative AF (POAF) in patients undergoing open-heart surgery. This study was conducted to assess the effect of N-acetylcysteine (NAC) in prevention of AF following coronary artery bypass graft (CABG) surgery.

METHODS

Three hundred patients who underwent CABG surgery were entered in the study. Patients with contraindications for beta-blockers and patients were simultaneously replacing or repairing the valve with open-heart surgery were excluded. The patients were randomly divided into two groups (n = 150) and they were received NAC plus carvedilol or carvedilol. The patients were monitored for 5 days after surgery and the incidence of AF during hospitalization was recorded.

RESULTS

AF was detected in 14 patients in the NAC with Carvedilol group (9.33%) and 23 patients in Carvedilol group (15.33%). There was no significant difference in the incidence of POAF between the two groups (p value = 0.112). The result of multivariable regression model represented that although the incidence of POAF was lower in NAC plus carvedilol group, it wasn't statistically significant (p value = 0.10).

CONCLUSIONS

NAC was not associated with a decreased incidence of AF following CABG surgery.

Vitamin C supplementation attenuates oxidative stress and improves erythrocyte deformability in cardiac surgery with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) depletes endogenous Vitamin C and generates oxidative stress in cardiac surgery. This study aimed to clarify whether Vitamin C supplementation reduces oxidant production and improves erythrocyte deformability in cardiac surgery with CPB. In a randomized and controlled design, 30 eligible patients undergoing cardiac surgery with hypothermic CPB were equally assigned to the Vitamin C group and control group. Subjects of the Vitamin C group and control group received an intravenous infusion of Vitamin C 20 mg·kg^-1 and a placebo during rewarming period of CPB, respectively. We measured the plasma level of reactive oxygen species (ROS) and phosphorylation levels of non-muscle myosin IIA (NMIIA) in erythrocyte membrane, as an index of erythrocyte deformability, before and after CPB. Vitamin C supplementation attenuated the surge in plasma ROS after CPB, mean 1.661 ± standard deviation 0.801 folds in the Vitamin C group and 2.743 ± 1.802 in the control group. The tyrosine phosphorylation level of NMIIA after CPB was upregulated in the Vitamin C group compared to the control group, 2.159 ± 0.887 folds and 1.384 ± 0.445 (P = 0.0237). In addition, the phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and focal adhesion kinase (FAK) in erythrocytes was concurrently enhanced in the Vitamin C group after CPB. The phosphorylation level of endothelial nitric oxide synthase in erythrocytes was significantly increased in the Vitamin C group (1.734 ± 0.371 folds) compared to control group (1.102 ± 0.249; P = 0.0061). Patients receiving Vitamin C had lower intraoperative blood loss and higher systemic vascular resistance after CPB compared to controls. Vitamin C supplementation attenuates oxidative stress and improves erythrocyte deformability via VASP/FAK signaling pathway in erythrocytes during CPB.

Efficacy of N-acetylcysteine in Preventing Acute Kidney Injury and Major Adverse Cardiac Events After Cardiac Surgery: A Meta-Analysis and Trial Sequential Analysis

Background

The effect of N-acetylcysteine (NAC), an antioxidant, on preventing acute kidney injury (AKI) and major adverse cardiac events (MACE) remains controversial. Therefore, we conducted this meta-analysis and trial sequential analysis to evaluate its efficacy on cardiac surgery-related adverse events.

Methods

PubMed, Embase, and Cochrane Library were searched for relevant studies from inception to June 2021. We selected randomized controlled trials comparing NAC with controls in patients undergoing cardiac surgery.

Results

Twenty-five studies including 2,444 patients met the inclusion criteria. The pooled results showed that there was no significant difference in the incidence of AKI between the NAC and control groups [relative risk (RR) = 0.91, 95% confidence interval (CI) = 0.77, 1.08, P = 0.28], but the trial sequential analysis (TSA) could not confirm this result. No difference was observed in the need for renal replacement therapy (RRT), all-cause mortality, MACE, length of stay in the intensive care unit (ICU), and length of stay in the hospital. Results of subgroup analysis results showed that intravenous infusion instead of oral NAC could significantly reduce the incidence of AKI and arrhythmia (RR = 0.84, 95% CI = 0.71, 0.99, P = 0.03, I² = 3% and RR = 0.74, 95% CI = 0.61, 0.91, P = 0.004, I² = 48%, respectively).

Conclusion

Intravenous administration of NAC can reduce the incidence of AKI and arrhythmia in patients after cardiac surgery, but cannot reduce all-cause mortality, AMI, cardiac insufficiency, and the number of patients using RRT. Oral NAC has no significant effect on the outcomes of patients after cardiac surgery.

N-Acetylcysteine for Cardiac Protection During Coronary Artery Reperfusion: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Coronary artery reperfusion is essential for the management of symptoms in the patients with myocardial ischemia. However, the benefit of reperfusion often comes at an expense of paradoxical injury, which contributes to the adverse events, and sometimes heart failure. Reperfusion is known to increase the production of reactive oxygen species (ROS). We address whether N-acetylcysteine (NAC) reduces the ROS and alleviates reperfusion injury by improving the clinical outcomes. A literature search for the randomized controlled trials (RCTs) was carried out in the five biomedical databases for testing the effects of NAC in patients undergoing coronary artery reperfusion by percutaneous coronary intervention, thrombolysis, or coronary artery bypass graft. Of 787 publications reviewed, 28 RCTs were identified, with a summary of 2,174 patients. A meta-analysis using the random effects model indicated that NAC administration during or prior to the reperfusion procedures resulted in a trend toward a reduction in the level of serum cardiac troponin (cTn) [95% CI, standardized mean difference (SMD) −0.80 (−1.75; 0.15), p = 0.088, n = 262 for control, 277 for NAC group], and in the incidence of postoperative atrial fibrillation [95% CI, relative risk (RR) 0.57 (0.30; 1.06), p = 0.071, n = 484 for control, 490 for NAC group]. The left ventricular ejection fraction or the measures of length of stay in intensive care unit (ICU) or in hospital displayed a positive trend that was not statistically significant. Among the nine trials that measured ROS, seven showed a correlation between the reduction of lipid peroxidation and improved clinical outcomes. These lines of evidence support the potential benefit of NAC as an adjuvant therapy for cardiac protection against reperfusion injury.

ROS-Induced Hepatotoxicity under Cypermethrin: Involvement of the Crosstalk between Nrf2/Keap1 and NF-κB/iκB-α Pathways Regulated by Proteasome

Cypermethrin (CMN) is a man-made insecticide, and its abuse has led to potential adverse effects, particularly in sensitive populations such as aquatic organisms. The present study was focused on the toxic phenotype and detoxification mechanism in grass carp (Ctenopharyngodon idella) after treatment with waterborne CMN (0.651 μg/L) for 6 weeks in vivo or 6.392 μM for 24 h in vitro. In vivo, we describe the toxic phenotype of the liver of grass carp in terms of pathological changes, serum transaminase levels, oxidative stress indexes, and apoptosis rates. RNA-Seq analysis (2 × 3 cDNA libraries) suggested a compromise of proteasome and oxidative phosphorylation signaling pathways under CMN exposure. Thus, these two pathways were chosen for the in vitro study, which suggested that the CMN intoxication-induced proteasome pathway caused hepatotoxicity in the liver cell line of grass carp (L8824 cells). Moreover, pretreatment with MG132, a proteasome inhibitor, displayed protection against the toxic effects of CMN by enhancing antioxidative and anti-inflammatory capability by directly inhibiting the proteasomal degradation of nuclear factor erythroid-2 related factor (Nrf2) and IκB-α, thus turning on the transcription of downstream genes of Nrf2 and NF-κB, respectively. Taken together, these results suggest proteasome activity as a reason for CMN-induced hepatotoxicity.

Mitochondrial and Sarcoplasmic Reticulum Interconnection in Cardiac Arrhythmia

Ca²⁺ plays a pivotal role in mitochondrial energy production, contraction, and apoptosis. Mitochondrial Ca²⁺-targeted fluorescent probes have demonstrated that mitochondria Ca²⁺ transients are synchronized with Ca²⁺ fluxes occurring in the sarcoplasmic reticulum (SR). The presence of specialized proteins tethering SR to mitochondria ensures the local Ca²⁺ flux between these organelles. Furthermore, communication between SR and mitochondria impacts their functionality in a bidirectional manner. Mitochondrial Ca²⁺ uptake through the mitochondrial Ca²⁺ uniplex is essential for ATP production and controlled reactive oxygen species levels for proper cellular signaling. Conversely, mitochondrial ATP ensures the proper functioning of SR Ca²⁺-handling proteins, which ensures that mitochondria receive an adequate supply of Ca²⁺. Recent evidence suggests that altered SR Ca²⁺ proteins, such as ryanodine receptors and the sarco/endoplasmic reticulum Ca²⁺ ATPase pump, play an important role in maintaining proper cardiac membrane excitability, which may be initiated and potentiated when mitochondria are dysfunctional. This recognized mitochondrial role offers the opportunity to develop new therapeutic approaches aimed at preventing cardiac arrhythmias in cardiac disease.

The effects of N-Acetylcysteine on serum level of inflammatory biomarkers in adults. Findings from a systematic review and meta-analysis of randomized clinical trials

PURPOSE

Randomized Clinical Trials (RCTs) have provided varied and conflicting findings regarding the effect of N-acetylcysteine (NAC) on inflammatory biomarkers. This study was conducted to review existing literature to determine whether NAC supplementation can affect inflammatory biomarkers in adults.

METHODS

Bibliographic databases of Scopus, and PubMed were used for relevant papers published until October 2019. Results were reported as weighted mean differences (WMD) with 95% confidence intervals (CI) using multi-level models. Cochrane's Q and I-squared (I2) tests were used to determine heterogeneity among studies.

RESULTS

Twenty-four RCTs which include 1057 sample size were entered to analysis. NAC doses and intervention duration ranged from 400 to 2000 mg/d, and 1 to 80 weeks, respectively. Oral supplementation of NAC reduced serum level of C-reactive protein (CRP) [WMD: -0.61 mg/L, 95% CI: -1.18 to -0.03, P = 0.039, I2 = 79.6%], and interleukin-6 (IL-6) [WMD: -0.43 pg/mL, 95% CI: -0.69 to -0.17, P = 0.001, I2 = 89.3%]. However, the effect of oral NAC supplementation on other inflammatory biomarkers was nonsignificant. Dose-response investigation showed a non-linear association between oral NAC supplementation with CRP.

CONCLUSION

Oral NAC supplementation reduced serum level of CRP and IL-6, but did not affect other inflammatory biomarkers. Nevertheless, more RCTs seems to be required to explore how NAC in different dosage and different routes of administration can affect inflammatory biomarkers.

N-acetylcysteine alleviates post-resuscitation myocardial dysfunction and improves survival outcomes via partly inhibiting NLRP3 inflammasome induced-pyroptosis

Background

NOD-like receptor 3 (NLRP3) inflammasome is necessary to initiate acute sterile inflammation. Increasing evidence indicates the activation of NLRP3 inflammasome induced pyroptosis is closely related to reactive oxygen species (ROS) in the sterile inflammatory response triggered by ischemia/reperfusion (I/R) injury. N-acetylcysteine (NAC) is an antioxidant and plays a protective role in local myocardial I/R injury, while its effect on post-resuscitation myocardial dysfunction, as well as its mechanisms, remain elusive. In this study, we aimed to investigate the effect of NAC on post-resuscitation myocardial dysfunction in a cardiac arrest rat model, and whether its underlying mechanism may be linked to ROS and NLRP3 inflammasome-induced pyroptosis.

Methods

The rats were randomized into three groups: (1) sham group, (2) cardiopulmonary resuscitation (CPR) group, and (3) CPR + NAC group. CPR group and CPR + NAC group went through the induction of ventricular fibrillation (VF) and resuscitation. After return of spontaneous circulation (ROSC), rats in the CPR and CPR + NAC groups were again randomly divided into two subgroups, ROSC 6 h and ROSC 72 h, for further analysis. Hemodynamic measurements and myocardial function were measured by echocardiography, and western blot was used to detect the expression of proteins.

Results

Results showed that after treatment with NAC, there was significantly better myocardial function and survival duration; protein expression levels of NLRP3, adaptor apoptosis-associated speck-like protein (ASC), Cleaved-Caspase-1 and gasdermin D (GSDMD) in myocardial tissues were significantly decreased; and inflammatory cytokines levels were reduced. The marker of oxidative stress malondialdehyde (MDA) decreased and superoxide dismutase (SOD) increased with NAC treatment.

Conclusions

NAC improved myocardial dysfunction and prolonged animal survival duration in a rat model of cardiac arrest. Moreover, possibly by partly inhibiting ROS-mediated NLRP3 inflammasome-induced pryoptosis.

A phase 2 trial of N-Acetylcysteine in Biliary atresia after Kasai portoenterostomy

BACKGROUND

Biliary atresia (BA) is a life-threatening liver disease of infancy, characterized by extrahepatic biliary obstruction, bile retention, and progressive liver injury. The Kasai portoenterostomy (KP) is BA's only nontransplant treatment. Its success is variable and depends on restoration of hepatic bile flow. Many adjunctive therapeutics have been studied to improve outcomes after the KP, but none demonstrate effectiveness. This study tests if N-acetylcysteine (NAC), a precursor to the choleretic glutathione, improves bile flow after KP.

METHODS

This report describes the design of an open-label, single center, Phase 2 study to determine the effect of NAC following KP on markers of bile flow and outcomes in BA. The intervention is intravenous NAC (150 mg/kg/day) administered continuously for seven days starting 0-24 h after KP. The primary outcome is normalization of total serum bile acid (TSBA) concentrations within 24 weeks of KP. The secondary objectives are to describe NAC therapy's effect on other clinical parameters followed in BA for 24 months and to report adverse events occurring with therapy. This study follows the "minimax" clinical trial design.

DISCUSSION

This is the first clinical trial to test NAC's effectiveness in improving bile flow after KP in BA. It introduces three important concepts for future BA therapeutic trials: (1) the "minimax" study design, a pertinent design for rare diseases because it detects potential effects quickly with small subject size; (2) the more sensitive bile flow marker, TSBAs, which may correlate with positive long-term outcomes better than traditional bile flow markers such as serum bilirubin; and (3) liver enzyme changes immediately after KP, which can be a guideline for potential drug-induced liver injury in other BA peri-operative adjunctive therapeutic trials.

Safety and efficacy of adding intravenous N-acetylcysteine to parenteral L-alanyl-L-glutamine in hospitalized patients undergoing surgery of the colon: a randomized controlled trial

BACKGROUND

Colon surgery can cause systemic inflammatory response syndrome (SIRS). There is a recent trend towards the use of antioxidant agents in the prevention or alleviation of the severity of postoperative SIRS, but its use is controversial as studies have shown conflicting results.

OBJECTIVES

Investigate the efficacy and tolerability of perioperative intravenous administration of N-acetylcysteine (NAC) as an antioxidant and anti-inflammatory agent in patients undergoing colon surgery.

DESIGN

Randomized, double-blinded, and controlled clinical trial.

SETTING

Surgical critical care unit in Egypt.

PATIENTS AND METHODS

Sixty patients who required admission to the ICU following colon surgery were enrolled in the study between July 2015 and October 2016. Eligibility included the need for parenteral nutrition for at least 5 days due to failure of or contraindication to enteral nutrition. Patients were randomly allocated using a computer-generated list to a loading dose of NAC followed by continuous infusion started one hour prior to induction, and continued over 48 hours, or to the control group, who received the same volume of dextrose 5%. Allocation was concealed using opaque, sealed envelopes under pharmacy control. The researcher, the anesthesiologist, the surgeon, and patients were blinded to the treatment allocation.

MAIN OUTCOME MEASURES

Clinical and laboratory evaluation for manifestations of SIRS, serum levels of tumor necrosis factor alpha and malondialdehyde, and occurrence of side effects in the study group.

SAMPLE SIZE

60 patients with mean (SD) ages of 56 (15.1) years in the study group (n=30) and 57.7 (12.3) years in the control group (n=30).

RESULTS

There was a significant difference in the mean serum level of ALT (22.6 (9.9) U/L in the study group vs. 31.1 (17.8) U/L in the control group, P=.028) after treatment with NAC, but differences between the groups in the serum level of tumor necrosis factor alpha and malondialdehyde after treatment were not significant. Serum levels of malondialdehyde increased in both groups after treatment P<.001. There was no statistically significant difference from baseline or between the groups after treatment in other clinical data and laboratory parameters following NAC administration, and only 6.6% of the patients in the study group experienced mild side effects.

CONCLUSIONS

Preoperative administration of NAC is safe, but its efficacy as an antioxidant and anti-inflammatory agent was not statistically significant and requires further investigation in a larger sample.

LIMITATIONS

Single-center study, small sample size, and short duration of NAC administration.

CLINICAL TRIALS REGISTRY

NCT03589495.

CONFLICT OF INTEREST

None.

N-acetylcysteine use among patients undergoing cardiac surgery: A systematic review and meta-analysis of randomized trials

Background

Cardiac surgeries are complex procedures aiming to re-establish coronary flow and correct valvular defects. Oxidative stress, caused by inflammation and ischemia-reperfusion injury, is associated with these procedures, increasing the risk of adverse outcomes. N-acetylcysteine (NAC) acts as an antioxidant by replenishing the glutathione stores, and emerging evidence suggests that NAC may reduce the risk of adverse perioperative outcomes. We conducted a systematic review and meta-analysis to investigate the addition of NAC to a standard of care among adult patients undergoing cardiac surgery.

Methods

We searched four databases (PubMed, EMBASE, CENTRAL, LILACS) from inception to October 2018 and the grey literaure for randomized controlled trials (RCTs) investigating the effect of NAC on pre-defined outcomes including mortality, acute renal insufficiency (ARI), acute cardiac insufficiency (ACI), hospital length of stay (HLoS), intensive care unit length of stay (ICULoS), arrhythmia and acute myocardial infarction (AMI). Reviewers independently screened potentially eligible articles, extracted data and assessed the risk of bias among eligible articles. We used the GRADE approach to rate the overall certainty of evidence for each outcome.

Results

Twenty-nine RCTs including 2,486 participants proved eligible. Low to moderate certainty evidence demonstrated that the addition of NAC resulted in a non-statistically significant reduction in mortality (Risk Ratio (RR) 0.71; 95% Confidence Interval (CI) 0.40 to 1.25), ARI (RR 0.92; 95% CI 0.79 to 1.09), ACI (RR 0.77; 95% CI 0.44 to 1.38), HLoS (Mean Difference (MD) 0.21; 95% CI -0.64 to 0.23), ICULoS (MD -0.04; 95% CI -0.29 to 0.20), arrhythmia (RR 0.79; 95% CI 0.52 to 1.20), and AMI (RR 0.84; 95% CI 0.48 to 1.48).

Limitations

Among eligible trials, we observed heterogeneity in the population and interventions including patients with and without kidney dysfunction and interventions that differed in route of administration, dosage, and duration of treatment. This observed heterogeneity was not explained by our subgroup analyses.

Conclusions

The addition of NAC during cardiac surgery did not result in a statistically significant reduction in clinical outcomes. A large randomized placebo-controlled multi-centre trial is needed to determine whether NAC reduces mortality.

Registration

PROSPERO CRD42018091191.

L. Ambrósio R, Calonga L, Curi SFBB, de T. Leme MF, Chone CT, Altemani JMC, Mazzola PG, Malaguti C, Vercesi AE, Lima CSP, Moriel P. Can acetylcysteine ameliorate cisplatin-induced toxicities and oxidative stress without decreasing antitumor efficacy? A randomized, double-blind, placebo-controlled trial involving patients with head and neck cancer

The protective antioxidant activity of acetylcysteine (NAC) against toxicity due to cisplatin has been reported in experimental models; however, its efficacy in patients has not been elucidated. The aim of this study was to investigate the possible protective effect of NAC on cisplatin-induced toxicity and the effect of NAC on clinical response and oxidative stress in patients treated for head and neck cancer. This was a randomized, double-blind, placebo-controlled trial conducted in patients receiving high-dose cisplatin chemotherapy concomitant to radiotherapy. Patients were randomly assigned to groups and received: (a) 600 mg NAC syrup, orally once daily at night for 7 consecutive days or (b) placebo, administered similarly to NAC. Nephro-, oto-, hepato-, myelo-, and gastrointestinal toxicities, clinical responses, and plasma and cellular markers of oxidative stress were evaluated. Fifty-seven patients were included (n = 28, NAC arm; and n = 29, placebo arm). A high prevalence of most types of toxicities was observed after cisplatin chemotherapy; however, the parameters were similar between the two groups. There was a predominance of partial response to treatment. In the cellular and plasmatic oxidative stress analyses, minor differences were observed. Overall, there was no statistically significant difference between the groups for all outcomes. These findings show that low-dose oral NAC does not protect patients with head and neck cancer from cisplatin-induced toxicities and oxidative stress. The antitumor efficacy of cisplatin was apparently not impaired by NAC.

Effects of N-acetyl cysteine and melatonin on early reperfusion injury in patients undergoing coronary artery bypass grafting: A randomized, open-labeled, placebo-controlled trial

OBJECTIVES

This study assessed the efficacy of oral consumption of N-acetyl cysteine (NAC) and melatonin (ML) in reducing early reperfusion injury and acute oxidative stress in patients undergoing coronary artery bypass grafting (CABG) with respect to the measurements of cardiac troponin I, lactate, malondealdehyde (MDA), and tumor necrosis factor-α (TNF-α) levels in the blood.

METHODS

This study was a randomized, open-label, placebo-controlled trial. Eighty eight patients, aged between 39 to 76 years and eligible for CABG, were recruited and randomly assigned into 3 intervention groups through a simple randomization method and underwent CABG surgery. Blood samples were withdrawn from arterial line, before the induction of anesthesia (before the start of surgery), after incision (before aortic cross-clamping), during global ischemia (during aortic cross-clamping), after aortic cross-clamping (on set of reperfusion), 15 minutes after reperfusion, and after recovery at the intense care unit. The blood samples were analyzed for troponin I, lactate, MDA and TNF-α levels.

RESULTS

There was no significant difference in influencing variables among the groups at the baseline. Overall mean troponin I, lactate, and TNF- α levels were significantly different between the intervention groups (all P < .001) at the recovery phase. Post-hoc pairwise comparisons showed that the differences of mean serum levels between ML and control groups were statistically significant for MDA, TNF- α, lactate, and troponin I (P < .001, P = .001, and P = .001, respectively). The differences between NAC and control groups and between ML and NAC groups were only significant for mean lactate level (P < .001).

CONCLUSION

The current study revealed that ML and NAC are potent antioxidants with similar efficacy in terms of reducing CABG related cardiac injury and oxidative stress with the dosage employed for the intervention.

Prevention of Cardiac Surgery-Associated Acute Kidney Injury

Numerous strategies have been evaluated to prevent early CSA-AKI. Although correction of hemodynamic problems is paramount, there are no clinical studies that compare different hemodynamic management or monitoring strategies with regard to their effect on kidney function. Pharmacologic strategies including diuretics, different classes of vasodilators and drugs with anti-inflammatory effects such as N-acetyl-cysteine, do not appear to be effective. Most of the studies are underpowered and use physiological rather than clinical endpoints. Further trials are warranted with fenoldopam and nesiritide (rhBNP). Observational and underpowered randomized studies show beneficial renal effects of off-pump technique and avoidance of aortic manipulation. There is very limited evidence for preoperative fluid loading and preemptive RRT. Potentially nephrotoxic agents should be used with caution in patients at risk of CSA-AKI. Tranexamic acid or aminocaproic acid should be preferred over aprotinin. No pharmacologic intervention has been adequately tested in the prevention of late CSA-AKI. A single-center study, including a predominance of patients after cardiac surgery, showed a decrease of kidney injury with tight glycemic control.

Compromised redox homeostasis, altered nitroso-redox balance, and therapeutic possibilities in atrial fibrillation

Although the initiation, development, and maintenance of atrial fibrillation (AF) have been linked to alterations in myocyte redox state, the field lacks a complete understanding of the impact these changes may have on cellular signalling, atrial electrophysiology, and disease progression. Recent studies demonstrate spatiotemporal changes in reactive oxygen species production shortly after the induction of AF in animal models with an uncoupling of nitric oxide synthase activity ensuing in the presence of long-standing persistent AF, ultimately leading to a major shift in nitroso–redox balance. However, it remains unclear which radical or non-radical species are primarily involved in the underlying mechanisms of AF or which proteins are targeted for redox modification. In most instances, only free radical oxygen species have been assessed; yet evidence from the redox signalling field suggests that non-radical species are more likely to regulate cellular processes. A wider appreciation for the distinction of these species and how both species may be involved in the development and maintenance of AF could impact treatment strategies. In this review, we summarize how redox second-messenger systems are regulated and discuss the recent evidence for alterations in redox regulation in the atrial myocardium in the presence of AF, while identifying some critical missing links. We also examine studies looking at antioxidants for the prevention and treatment of AF and propose alternative redox targets that may serve as superior therapeutic options for the treatment of AF.

Cardiovascular effects of hyperoxia during and after cardiac surgery

During and after cardiac surgery with cardiopulmonary bypass, high concentrations of oxygen are routinely administered, with the intention of preventing cellular hypoxia. We systematically reviewed the literature addressing the effects of arterial hyperoxia. Extensive evidence from pre-clinical experiments and clinical studies in other patient groups suggests predominant harm, caused by oxidative stress, vasoconstriction, perfusion heterogeneity and myocardial injury. Whether these alterations are temporary and benign, or actually affect clinical outcome, remains to be demonstrated. In nine clinical cardiac surgical studies in low-risk patients, higher oxygen targets tended to compromise cardiovascular function, but did not affect clinical outcome. No data about potential beneficial effects of hyperoxia, such as reduction of gas micro-emboli or post-cardiac surgery infections, were reported. Current evidence is insufficient to specify optimal oxygen targets. Nevertheless, the safety of supraphysiological oxygen suppletion is unproven. Randomised studies with a variety of oxygen targets and inclusion of high-risk patients are needed to identify optimal oxygen targets during and after cardiac surgery.

Effectiveness of intravenous infusion of N-acetylcysteine in cirrhotic patients undergoing major abdominal surgeries

BACKGROUND

Postoperative acute kidney injury (AKI) is common in patients with chronic liver disease. We prospectively evaluated effectiveness of the N-acetylcysteine (NAC) in preserving postoperative renal functions in cirrhotic patients undergoing major abdominal surgeries.

MATERIALS AND METHODS

A total of 60 cirrhotic patients child A to B were randomized into two groups of 30 each. NAC groupwas received intravenous infusion of NAC (1200 mg/12h starting immediately before surgery and continued for 72h h postoperative) and controls group received a similar volume of glucose 5% solution as a a placebo. Systemic hemodynamics, hepatic and renal functions, serum cystatin C and cystatin C glomerular filtration rate (GFR) (GFR) were compared between both groups.

RESULTS

Serum level of cystatin C was raised significantly above the basal value at postoperative day 1 and day 3 associated with significantly decreased in cystatin C GFR below the basal value in the control group (P = 0.001). 6 (20%) (PP = 0.03) in control group developed AKI based on cystatin C GFR criteria (GFR <55 ml/min/1.73m(2)). Mean values of alanine aminotransferase and aspartate aminotransferase were increased significantly above the basal values in both groups, but the increases were significantly lower in NAC group (P = 0.00). Chest infection was significantly lower associated with shorter hospital stay in the NAC group than the control group.

CONCLUSION

Intravenous administration of NAC NAC in cirrhotic patients undergoing major abdominal surgeries reduces the incidence of cystatin C GFR-based AKI, postoperative renal and liver functions were well-preserved and improved outcome.

Addition of N-acetyl cysteine to carvedilol decreases the incidence of acute renal injury after cardiac surgery

BACKGROUND

Oxidative stress and inflammation during cardiac surgery may be associated with acute renal injury (ARI). N-acetyl cysteine (NAC) and carvedilol have antioxidant and anti-inflammatory properties.

HYPOTHESIS

A combination of carvedilol and NAC should decrease the incidence of ARI more than metoprolol or carvedilol.

METHODS

Patients undergoing cardiac surgery were randomized to metoprolol, carvedilol, or carvedilol plus NAC. End points were occurrence of ARI and change in preoperative to postoperative peak creatinine levels.

RESULTS

ARI incidence was lower in the carvedilol plus NAC group compared with the metoprolol (21.0% vs 42.1%; P = 0.002) or carvedilol (21.0% vs 38.6%; P = 0.006) groups, but was similar between the metoprolol and carvedilol groups (P = 0.62). Preoperative and postoperative day 1 creatinine levels were similar among the metoprolol (1.02 [0.9-1.2] and 1.2 [0.92-1.45]) the carvedilol (1.0 [0.88-1.08] and 1.2 [0.9-1.5]) and the carvedilol plus NAC groups (1.06 [0.9-1.18] and 1.1 [1.0-1.21] mg/dL; all P values >0.05). Postoperative day 3, day 5, and peak creatinine levels were lower in the carvedilol plus NAC group (1.11 [1.0-1.23], 1.14 [1.0-1.25] and 1.15 [1.0-1.25]) as compared with the metoprolol (1.4 [1.3-1.49], 1.3 [1.0-1.54] and 1.3 [1.0-1.54]) or carvedilol groups (1.2 [1.0-1.52], 1.25 [1.0-1.52] and 1.25 [1.0-1.55] mg/dL; all P values <0.05), but were similar between the metoprolol and carvedilol groups (all P values >0.05).

CONCLUSIONS

Combined carvedilol and NAC decreased ARI incidence as compared with carvedilol or metoprolol. No difference was detected between carvedilol and metoprolol.

Preoperative hydroperoxide concentrations are associated with a risk of postoperative complications after cardiac surgery

This study aimed to assess whether preoperative oxidative stress levels can predict postoperative complications in patients undergoing cardiac surgery. Ninety-five cardiac surgery patients received an assessment of preoperative oxidative stress by measurement of hydroperoxide values in blood via the d-Rom test. Area under the receiver operating characteristic curve and also multivariate logistic regression were used to evaluate the prognostic significance of preoperative hydroperoxide concentrations in predicting the occurrence of major organ morbidity and mortality (MOMM). MOMM included death, deep sternal infection, reoperation, stroke, renal failure requiring haemodialysis and prolonged ventilation (>48 hours). The ability of preoperative hydroperoxide concentrations to predict MOMM was not significantly different from that of the European system for cardiac operative risk evaluation (EuroSCORE) (area under the receiver operating characteristic curve 0.822 versus 0.821 respectively, P=0.983). The optimal threshold value of hydroperoxide concentration to differentiate between patients with and without MOMM was 450 UCarr (sensitivity, 87.0%; specificity, 81.9%). Duration of intensive care unit stay, mechanical ventilation time and hospital stay were significantly longer in patients with preoperative hydroperoxide concentrations ≥450 UCarr (H group) compared to those patients with preoperative hydroperoxide concentrations <450 UCarr (L group). An increase in preoperative hydroperoxide concentrations remained associated with an increased risk of MOMM (odds ratios: 1.01, 95% confidence interval: 1.00 to 1.03) and prolonged intensive care unit stay (odds ratio 1.01, 95% confidence interval: 1.00 to 1.02), after adjusting for age, gender and EuroSCORE. In conclusion, an increased hydroperoxide concentration before cardiac surgery is an independent risk factor for severe postoperative complications.

Efficacy of N-acetylcysteine in preventing atrial fibrillation after cardiac surgery: a meta-analysis of published randomized controlled trials

Background

Atrial fibrillation is a common complication after cardiac surgery. The aim of this study is to evaluate whether N-acetylcysteine (NAC) could prevent postoperative atrial fibrillation (POAF).

Methods

PubMed, Embase and Cochrane Center Register of Controlled Trials were searched from the date of their inception to 1 July 2013 for relevant randomized controlled trials (RCTs), in which NAC was compared with controls for adult patients undergoing cardiac surgery. Outcome measures comprised the incidence of POAF, all-cause mortality, length of intensive care unit (ICU) stay, hospital length of stay, and the incidence of cerebrovascular events. The meta-analysis was performed with the fixed-effect model or random-effect model according to the heterogeneity.

Results

We retrieved ten studies enrolling a total of 1026 patients. Prophylactic NAC reduced the incidence of POAF (OR 0.56; 95% CI 0.40 to 0.77; P < 0.001) and all-cause mortality (OR 0.40; 95% CI 0.17 to 0.93; P = 0.03) compared with controls, but failed to reduce the stay in ICU and overall stay in hospital. No difference in the incidence of cerebrovascular events was observed.

Conclusions

Prophylactic use of NAC could reduce the incidence of POAF and all-cause mortality in adult patients undergoing cardiac surgery. However, larger RCTs evaluating these and other postoperative complication endpoints are needed.

Inflammation in new-onset atrial fibrillation after cardiac surgery: a systematic review

BACKGROUND

Postoperative new-onset atrial fibrillation (PNAF) is the most common complication following cardiac surgery. The pathogenesis of PNAF is multifactorial. The concept of the postoperative inflammatory response, as a potential underlying mechanism has been extensively studied. This review aims to provide a comprehensive summary of literature relevant to the association between the inflammatory response following cardiac surgery and PNAF.

DESIGN

MEDLINE, EMBASE and the Cochrane Central Register were systematically reviewed by two independent investigators for studies published between January 1980 and May 2012, in which an association between serum markers of inflammation and PNAF was evaluated, or the effect of drugs with anti-inflammatory properties on the risk of PNAF.

RESULTS

Sixty-three studies met selection criteria (39 observational and 24 randomized studies) including 27,363 patients. The mean incidence of PNAF after cardiac surgery was 25·5%. Elevated levels of various inflammatory mediators were associated with PNAF, and the most consistent association was found between white blood cell count and PNAF. Of the drugs with anti-inflammatory properties, statins gave the best protective effect against PNAF, followed by anti-oxidants, steroids and colchicine. Nonsteroidal anti-inflammatory drugs did not prevent PNAF significantly.

CONCLUSION

The postoperative inflammation response may play a role in the pathogenesis of PNAF. However, of the inflammation biomarkers, only elevated white blood cell count reliably predicts PNAF. Pre- and perioperative use of statins and several other drugs with anti-inflammatory properties reduce the incidence of PNAF.

Antioxidant supplementations for prevention of atrial fibrillation after cardiac surgery: an updated comprehensive systematic review and meta-analysis of 23 randomized controlled trials

This systematic review with meta-analysis sought to determine the impact of antioxidants (N-acetylcysteine [NAC], polyunsaturated fatty acids [PUFAs] and vitamins) on incidence of postoperative atrial fibrillation (POAF) and duration of length of hospital stay. Medline, Embase, Elsevier, Sciences online database and Google Scholar literature search was made for studies in randomized controlled trials. The effect sizes measured were odds ratio (OR) for categorical variable and standard mean difference (SMD) with 95% confidence interval (CI) for calculating differences between mean values of duration of hospitalization in intervention and control groups. A value of P < 0.1 for Q-test or I(2) > 50% indicated significant heterogeneity between the studies. Literature search of all major databases retrieved 355 studies. After screening, a total of 23 trials were identified that reported outcomes of 4278 patients undergoing cardiac surgery. Pooled effects estimates on POAF showed a significant reduction after NAC (OR: 0.56, 95% CI: 0.40-0.77, P < 0.001), PUFA (OR: 0.84, 95% CI: 0.71-0.99, P = 0.03) and vitamin C treatment (OR: 0.50, 95% CI: 0.27-0.91, P = 0.02). Hospital length of stay was not reduced after NAC therapy (SMD: 0.082, 95% CI -0.09 to 0.25, P = 0.3), but could be decreased with PUFA (SMD: -0.185, 95% CI: -0.35 to -0.018, P = 0.03) and vitamin C (SMD: -0.325, 95% CI -0.50 to -0.14, P < 0.01). In conclusion, perioperative antioxidant supplementations with NAC, PUFA and vitamin C prevent atrial fibrillation after cardiac surgery. Moreover, PUFA and vitamin C are capable to reduce hospital stay, whereas NAC lacks this capacity.

Oxidative status, inflammation, and postoperative atrial fibrillation with metoprolol vs carvedilol or carvedilol plus N-acetyl cysteine treatment

BACKGROUND

Atrial fibrillation is associated with inflammation and oxidative stress.

HYPOTHESIS

Carvedilol and N-acetyl cysteine (NAC) combination decreases inflammation, oxidative stress, and postoperative atrial fibrillation (POAF) rates more than metoprolol or carvedilol.

METHODS

Preoperative and postoperative total oxidative stress (TOS), total antioxidant capacity (TAC), and white blood cells (WBC) were measured in metoprolol, carvedilol, or carvedilol plus NAC groups, and association with POAF was evaluated.

RESULTS

Preoperative TAC, TOS, and WBC levels were similar among the groups. Postoperative TAC levels were lower in the metoprolol group compared with the carvedilol group (1.0 vs 1.4) or the carvedilol plus NAC group (1.0 vs 1.9) and were also lower in the carvedilol group compared with the carvedilol plus NAC group (all P < 0.0001). Postoperative TOS levels were higher in the metoprolol group as compared with the carvedilol (29.6 vs 24.2; P < 0.0001) or the carvedilol plus NAC groups (P < 0.0001), and were also higher in the carvedilol group as compared with the carvedilol plus NAC group (24.2 vs 19.3; P < 0.0001). Postoperative WBC counts were lower in the carvedilol plus NAC group compared with the metoprolol group (12.9 vs 14.8; P = 0.004), were similar between the carvedilol and the metoprolol groups (13 vs 14.8) and between the carvedilol plus NAC group and the carvedilol group (both P > 0.05). Postoperative TAC, TOS, and WBC were associated with POAF.

CONCLUSIONS

Carvedilol plus NAC reduced oxidative stress and inflammation compared with metoprolol and decreased oxidative stress compared with carvedilol. Postoperative TAC, TOS, and WBC were associated with POAF.

The Protective Role of Resveratrol against Arsenic Trioxide-Induced Cardiotoxicity

Arsenic trioxide (As₂O₃) shows substantial anticancer activity in patients with acute promyelocytic leukemia (APL). Unfortunately, limiting the application of this effective agent to APL patients is severe cardiotoxicity. Resveratrol, the natural food-derived polyphenolic compound, is well known for its antioxidant properties and protects the cardiovascular system. But the potential role of resveratrol against As₂O₃ in heart via nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) is unclear. The present study evaluated the effects of pretreatment with resveratrol and As₂O₃ on oxidative stress and cardiac dysfunction in rat. In the present study, resveratrol decreased As₂O₃-induced reactive oxygen species generation, oxidative DNA damage, and pathological alterations. In addition, cardiac dysfunction parameters, intracellular calcium and arsenic accumulation, glutathione redox ratio, and cAMP deficiency levels were observed in As₂O₃-treated rats; these changes were attenuated by resveratrol. Furthermore, resveratrol significantly prohibited the downregulation of both Nrf2 and HO-1 gene expressions that were downregulated by As₂O₃, whereas resveratrol did not alter As₂O₃-induced nitric oxide formation. Thus, the protective role of resveratrol against As₂O₃-induced cardiotoxicity is implemented by the maintenance of redox homeostasis (Nrf2-HO-1 pathway) and facilitating arsenic efflux. Our findings suggest coadministration with resveratrol, and As₂O₃ might provide a novel therapeutic strategy for APL.

Oxidative damage in clinical ischemia/reperfusion injury: a reappraisal

AIMS

Ischemia/reperfusion (I/R) injury is a common clinical problem. Although the pathophysiological mechanisms underlying I/R injury are unclear, oxidative damage is considered a key factor in the initiation of I/R injury. Findings from preclinical studies consistently show that quenching reactive oxygen and nitrogen species (RONS), thus limiting oxidative damage, alleviates I/R injury. Results from clinical intervention studies on the other hand are largely inconclusive. In this study, we systematically evaluated the release of established biomarkers of oxidative and nitrosative damage during planned I/R of the kidney and heart in a wide range of clinical conditions.

RESULTS

Sequential arteriovenous concentration differences allowed specific measurements over the reperfused organ in time. None of the biomarkers of oxidative and nitrosative damage (i.e., malondialdehyde, 15(S)-8-iso-prostaglandin F2α, nitrite, nitrate, and nitrotyrosine) were released upon reperfusion. Cumulative urinary measurements confirmed plasma findings. As of these negative findings, we tested for oxidative stress during I/R and found activation of the nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of oxidative stress signaling.

INNOVATION

This comprehensive, clinical study evaluates the role of RONS in I/R injury in two different human organs (kidney and heart). Results show oxidative stress, but do not provide evidence for oxidative damage during early reperfusion, thereby challenging the prevailing paradigm on RONS-mediated I/R injury.

CONCLUSION

Findings from this study suggest that the contribution of oxidative damage to human I/R may be less than commonly thought and propose a re-evaluation of the mechanism of I/R.

Imaging ROS signaling in cells and animals

Reactive oxygen species (ROS) act as essential cellular messengers, redox regulators, and, when in excess, oxidative stressors that are widely implicated in pathologies of cancer and cardiovascular and neurodegenerative diseases. Understanding such complexity of the ROS signaling is critically hinged on the ability to visualize and quantify local, compartmental, and global ROS dynamics at high selectivity, sensitivity, and spatiotemporal resolution. The past decade has witnessed significant progress in ROS imaging at levels of intact cells, whole organs or tissues, and even live organisms. In particular, major advances include the development of novel synthetic or genetically encoded fluorescent protein-based ROS indicators, the use of protein indicator-expressing animal models, and the advent of in vivo imaging technology. Innovative ROS imaging has led to important discoveries in ROS signaling—for example, mitochondrial superoxide flashes as elemental ROS signaling events and hydrogen peroxide transients for wound healing. This review aims at providing an update of the current status in ROS imaging, while identifying areas of insufficient knowledge and highlighting emerging research directions.

Acute kidney injury and critical cardiac disease

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The survival of patients with critical congenital heart disease is seldom in question. Consequently, the focus has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating 30% to 40% of adult and pediatric cardiac surgeries. Patients who require dialysis are at high risk of mortality, but even minor degrees of postoperative AKI portend a significant increase in mortality and morbidity.

ROS regulation of microdomain Ca(2+) signalling at the dyads

Reactive oxygen species (ROS) are emerging as centre-stage players in cardiac functional regulation. ROS and Ca(2+) signals converge at dyads, the structural and functional units of cardiac excitation-contraction coupling. These two prominent signalling systems are intertwined with ROS modulation of the entire Ca(2+)-signalling network, and vice versa. While constitutively generated homoeostatic ROS are important in setting the redox potential of the intracellular milieu, dynamic signalling ROS shape microdomain and global Ca(2+) signals on both the beat-to-beat and greater time scales. However, ROS effects are complex and subtle, characterized by multiphasic and bidirectional Ca(2+) responses; and sustained oxidative stress may lead to compromised contractility and arrhythmogenicity. These new understandings should be leveraged to harness ROS for their beneficial roles while avoiding deleterious effects in the heart.

Perioperative acute kidney injury

The incidence of acute kidney injury (AKI) is generally 5-7.5% in all acute care hospitalizations and accounts for up to 20% of admissions to intensive care units (ICUs). Of all of the cases of AKI during hospitalization, approximately 30-40% are observed in operative settings. AKI is a serious morbidity that is associated with greater length of hospital stay, high risk of hospital mortality, and increased risk of incident and progressive chronic kidney disease. The incidence of AKI is variable depending on the specific surgical setting under consideration. Much of our knowledge regarding the epidemiology of AKI is derived from studies related to cardiac or vascular surgery. With limited treatment options, prevention of AKI and amelioration of its severity remain important cornerstones of improving patient outcomes. The magnitude of the problem and the unique set of patient characteristics calls for a multidisciplinary approach for the perioperative management of renal complications. The purpose of the review presented here is to discuss the current knowledge regarding the epidemiology and risk factors, outcomes, diagnoses, and prevention and treatment of AKI during the perioperative period in cardiovascular and noncardiovascular surgical settings.

N-acetylcysteine for sepsis and systemic inflammatory response in adults

BACKGROUND

Death is common in systemic inflammatory response syndrome (SIRS) or sepsis-induced multisystem organ failure and it has been thought that antioxidants such as N-acetylcysteine could be beneficial.

OBJECTIVES

We assessed the clinical effectiveness of intravenous N-acetylcysteine for the treatment of patients with SIRS or sepsis.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Clinical Trials (CENTRAL) (The Cochrane Library 2011, Issue 12); MEDLINE (January 1950 to January 2012); EMBASE (January 1980 to January 2012); CINAHL (1982 to January 2012); the NHS Trusts Clinical Trials Register and Current Controlled Trials (www.controlled-trials.com); LILACS; KoreaMED; MEDCARIB; INDMED; PANTELEIMON; Ingenta; ISI Web of Knowledge and the National Trials Register to identify all relevant randomized controlled trials available for review.

SELECTION CRITERIA

We included only randomized controlled trials (RCTs) in the meta-analysis.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, quality assessment and data extraction. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic.

MAIN RESULTS

We included 41 fully published studies (2768 patients). Mortality was similar in the N-acetylcysteine group and the placebo group (RR 1.06, 95% CI 0.79 to 1.42; I(2) = 0%). Neither did N-acetylcysteine show any significant effect on length of stay, duration of mechanical ventilation or incidence of new organ failure. Early application of N-acetylcysteine to prevent the development of an oxidato-inflammatory response did not affect the outcome, nor did late application that is after 24 hours of developing symptoms. Late application was associated with cardiovascular instability.

AUTHORS' CONCLUSIONS

Overall, this meta-analysis puts doubt on the safety and utility of intravenous N-acetylcysteine as an adjuvant therapy in SIRS and sepsis. At best, N-acetylcysteine is ineffective in reducing mortality and complications in this patient population. At worst, it can be harmful, especially when administered later than 24 hours after the onset of symptoms, by causing cardiovascular depression. Unless future RCTs provide evidence of treatment effect, clinicians should not routinely use intravenous N-acetylcysteine in SIRS or sepsis and academics should not promote its use.

Mesenchymal stromal cells in renal ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is an inevitable consequence of organ transplantation and a major determinant of patient and graft survival in kidney transplantation. Renal I/R injury can lead to fibrosis and graft failure. Although the exact sequence of events in the pathophysiology of I/R injury remains unknown, the role of inflammation has become increasingly clear. In this perspective, mesenchymal stromal cells (MSCs) are under extensive investigation as potential therapy for I/R injury, since MSCs are able to exert immune regulatory and reparative effects. Various preclinical studies indicate the beneficial effects of MSCs in ameliorating renal injury and accelerating tissue repair. These versatile cells have been shown to migrate to sites of injury and to enhance repair by paracrine mechanisms instead of by differentiating and replacing the injured cells. The first phase I studies of MSCs in human renal I/R injury and kidney transplantation have been started, and results are awaited soon. In this review, preliminary results and opportunities of MSCs in human renal I/R injury are summarized. We might be heading towards a cell-based paradigm shift in the treatment of renal I/R injury.

N-Acetylcysteine supplementation for the prevention of atrial fibrillation after cardiac surgery: a meta-analysis of eight randomized controlled trials

BACKGROUND

Atrial fibrillation is the most common type of arrhythmia after cardiac surgery. An increasing body of evidence demonstrates that oxidative stress plays a pivotal role in the pathophysiology of atrial fibrillation. N-acetylcysteine (NAC) is a free radical scavenger, and may attenuate this pathophysiologic response and reduce the incidence of postoperative AF (POAF). However, it is unclear whether NAC could effectively prevent POAF. Therefore, this meta-analysis aims to assess the efficacy of NAC supplementation on the prevention of POAF.

METHODS

Medline and Embase were systematically reviewed for studies published up to November 2011, in which NAC was compared with controls for adult patients undergoing cardiac surgery. Outcome measures comprised the incidence of POAF and hospital length of stay (LOS). The meta-analysis was performed with the fixed-effect model or random-effect model according to the heterogeneity.

RESULTS

Eight randomized trials incorporating 578 patients provided the best evidence and were included in this meta-analysis. NAC supplementation significantly reduced the incidence of POAF (OR 0.62, 95% CI 0.41 to 0.93; P = 0.021) compared with controls, but had no effect on LOS (WMD -0.07, 95% CI -0.42 to 0.28; P = 0.703).

CONCLUSIONS

The prophylactic NAC supplementation may effectively reduce the incidence of POAF. However, the overall quality of current studies is poor and further research should focus on adequately powered randomized controlled trials with POAF incidence as a primary outcome measure.

The cellular and molecular origin of reactive oxygen species generation during myocardial ischemia and reperfusion

Myocardial ischemia-reperfusion injury is an important cause of impaired heart function in the early postoperative period subsequent to cardiac surgery. Reactive oxygen species (ROS) generation increases during both ischemia and reperfusion and it plays a central role in the pathophysiology of intraoperative myocardial injury. Unfortunately, the cellular source of these ROS during ischemia and reperfusion is often poorly defined. Similarly, individual ROS members tend to be grouped together as free radicals with a uniform reactivity towards biomolecules and with deleterious effects collectively ascribed under the vague umbrella of oxidative stress. This review aims to clarify the identity, origin, and progression of ROS during myocardial ischemia and reperfusion. Additionally, this review aims to describe the biochemical reactions and cellular processes that are initiated by specific ROS that work in concert to ultimately yield the clinical manifestations of myocardial ischemia-reperfusion. Lastly, this review provides an overview of several key cardioprotective strategies that target myocardial ischemia-reperfusion injury from the perspective of ROS generation. This overview is illustrated with example clinical studies that have attempted to translate these strategies to reduce the severity of ischemia-reperfusion injury during coronary artery bypass grafting surgery.