N-acetylcysteine pretreatment of cardiac surgery patients influences plasma neutrophil elastase and neutrophil influx in bronchoalveolar lavage fluid

Perioperative N-acetylcysteine: evidence and indications

Nonopioid analgesics serve to improve analgesia and limit side effects and risks of perioperative opioids. N-acetylcysteine (NAC), the primary treatment of acetaminophen toxicity, may have perioperative indications, including analgesia. NAC impacts glutathione synthesis, oxidant scavenging, glutamate receptor modulation and neuroinflammation. Potential perioperative benefits include arrhythmia prevention after cardiac surgery, decreased contrast-induced nephropathy, improved post-transplant liver function and superior pulmonary outcomes with general anesthesia. NAC may improve perioperative analgesia, with some studies displaying a reduction in postoperative opioid use. NAC is generally well tolerated with an established safety profile. NAC administration may predispose to gastrointestinal effects, while parenteral administration may carry a risk of anaphylactoid reactions, including bronchospasm. Larger randomized trials may clarify the impact of NAC on perioperative analgesic outcomes.

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.

Friend or Foe? The Roles of Antioxidants in Acute Lung Injury

Acute lung injury (ALI) is an acute hypoxic respiratory insufficiency caused by various intra- and extra-pulmonary injury factors. The oxidative stress caused by excessive reactive oxygen species (ROS) produced in the lungs plays an important role in the pathogenesis of ALI. ROS is a "double-edged sword", which is widely involved in signal transduction and the life process of cells at a physiological concentration. However, excessive ROS can cause mitochondrial oxidative stress, leading to the occurrence of various diseases. It is well-known that antioxidants can alleviate ALI by scavenging ROS. Nevertheless, more and more studies found that antioxidants have no significant effect on severe organ injury, and may even aggravate organ injury and reduce the survival rate of patients. Our study introduces the application of antioxidants in ALI, and explore the mechanisms of antioxidants failure in various diseases including it.

Preventing the development of severe COVID-19 by modifying immunothrombosis

BACKGROUND

COVID-19-associated acute respiratory distress syndrome (ARDS) is associated with significant morbidity and high levels of mortality. This paper describes the processes involved in the pathophysiology of COVID-19 from the initial infection and subsequent destruction of type II alveolar epithelial cells by SARS-CoV-2 and culminating in the development of ARDS.

MAIN BODY

The activation of alveolar cells and alveolar macrophages leads to the release of large quantities of proinflammatory cytokines and chemokines and their translocation into the pulmonary vasculature. The presence of these inflammatory mediators in the vascular compartment leads to the activation of vascular endothelial cells platelets and neutrophils and the subsequent formation of platelet neutrophil complexes. These complexes in concert with activated endothelial cells interact to create a state of immunothrombosis. The consequence of immunothrombosis include hypercoagulation, accelerating inflammation, fibrin deposition, migration of neutrophil extracellular traps (NETs) producing neutrophils into the alveolar apace, activation of the NLRP3 inflammazome, increased alveolar macrophage destruction and massive tissue damage by pyroptosis and necroptosis Therapeutic combinations aimed at ameliorating immunothrombosis and preventing the development of severe COVID-19 are discussed in detail.

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.

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.

N-acetylcysteine advancement of surfactant therapy in experimental meconium aspiration syndrome: possible mechanisms

Meconium aspiration syndrome (MAS) is meconium-induced respiratory failure of newborns associated with activation of inflammatory and oxidative pathways. For severe MAS, exogenous surfactant treatment is used which improves respiratory functions but does not treat the inflammation. Oxidative process can lead to later surfactant inactivation; hence, surfactant combination with antioxidative agent may enhance the therapeutic effect. Young New Zealand rabbits were instilled by meconium suspension and treated by surfactant alone, N-acetylcysteine (NAC) alone or by their combination and oxygen-ventilated for 5 h. Blood samples were taken before and 30 min after meconium application and 30 min, 1, 3 and 5 h after the treatment for evaluating of oxidative damage, total leukocyte count, leukocyte differential count and respiratory parameters. Leukocyte differential was assessed also in bronchoalveolar lavage fluid. NAC alone had only mild therapeutic effect on MAS. However, the combination of NAC and surfactant facilitated rapid onset of therapeutic effect in respiratory parameters (oxygenation index, PaO(2)/FiO(2)) compared to surfactant alone and was the only treatment which prevented neutrophil migration into the lungs, oxidative damage and lung edema. Moreover, NAC suppressed IL-8 and IL-beta formation and thus seems to be favorable agent for improving surfactant therapy in MAS.

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.

New therapeutic option with N-acetylcysteine for primary sclerosing cholangitis: two case reports

Primary sclerosing cholangitis is a progressive, cholestatic hepatic disease of unknown etiology. It is characterized by progressive inflammation, destruction, and fibrosis of the intrahepatic and extrahepatic bile ducts. Several medical therapies have been tried such as penicilamin, colchicine, methatraxate, cyclosporine, tacrolimus, and ursodeoxycholic acid. Treatment with mucolytic agents in excessively high viscosity conditions appears to have an important role. N-acetylcysteine (NAC), as a mucolytic agent, may fascilitate the drainage in partial obstructions by decreasing the mucous viscosity. We suggest that NAC and ursodeoxycholic acid have markedly positive effects on the clinical course of cholangitis and cholestasis when used together by affecting bile viscosity. Here, we present two cases treated with NAC. NAC capsul therapies at 800 mg/day were administered to two patients with primary sclerosing cholangitis. Clinical and laboratory parameters of patients saw significant improvement.

L-NAME and L-arginine differentially ameliorate cigarette smoke-induced emphysema in mice

Nitric oxide (NO) represents one of the most important intra- and extracellular mediators and takes part in both biologic and pathologic processes. This study aimed to verify the treatment with an NO inhibitor and an NO substrate in pulmonary emphysema induced by cigarette smoke (CS) in a murine model. We compared N-acetylcysteine (NAC), a precursor of glutathione, to G-nitro-L-arginine-methyl ester or L-NAME (LN), which is an NO inhibitor, and to l-arginine (LA), which is a substrate for NO formation. Mice were divided into several groups: control, CS, CS + LN, CS + LA, and CS + NAC. Control and CS groups were treated daily with a vehicle, while CS + LN, CS + LA, and CS + NAC groups were treated daily with LN (60 mg/kg), LA (120 mg/kg) and NAC (200 mg/kg), respectively. The bronchoalveolar lavage was analyzed and the lungs were removed for histological and biochemical analysis. CS increases neutrophil number. Neutrophil number was lowest in CS + LN, followed by CS + LA. The lungs of CS + LN, CS + LA and CS + NAC mice were protected compared to the lungs of CS mice, but not equal to the quality of lungs in control mice. The CS group also exhibited increased oxidative stress, which was also present in the CS + LN group and to a lesser extent in the CS + LA group. Tissue inhibitor of metalloproteinase 1 and 2 increased in the CS + LN group and to a lesser extent in the CS + LA group relative to the control group. These results suggest that LN and LA treatment protected the mouse lung from CS. However, NAC treatment was more than LN and LA. We suggest that the protection conferred by LN treatment requires a balance between proteases and antiproteases, and that protection conferred by LA treatment involves the balance between oxidants and antioxidants.

Role of elastases in the pathogenesis of chronic obstructive pulmonary disease: implications for treatment

Neutrophil elastase, metalloproteinases, and their inhibitors play an important role in the development of chronic obstructive pulmonary disease (COPD), resulting in extensive tissue damage and malfunctioning of the airways. Nearly fifty years after the protease-antiprotease imbalance hypothesis has been suggested for the cause of emphysema, it is still appealing, but it does not explain the considerable variation in the clinical expressions of emphysema. However, there are many recent research findings to support the imbalance hypothesis as will be shown in this review. Although limited, there might be openings for the treatment of the disease.

Health effects of quercetin: from antioxidant to nutraceutical

Quercetin, a member of the flavonoids family, is one of the most prominent dietary antioxidants. It is ubiquitously present in foods including vegetables, fruit, tea and wine as well as countless food supplements and is claimed to exert beneficial health effects. This includes protection against various diseases such as osteoporosis, certain forms of cancer, pulmonary and cardiovascular diseases but also against aging. Especially the ability of quercetin to scavenge highly reactive species such as peroxynitrite and the hydroxyl radical is suggested to be involved in these possible beneficial health effects. Consequently, numerous studies have been performed to gather scientific evidence for these beneficial health claims as well as data regarding the exact mechanism of action and possible toxicological aspects of this flavonoid. The purpose of this review is to evaluate these studies in order to elucidate the possible health-beneficial effects of the antioxidant quercetin. Firstly, the definitions as well as the most important aspects regarding free radicals, antioxidants and oxidative stress will be discussed as background information. Subsequently, the mechanism by which quercetin may operate as an antioxidant (tested in vitro) as well as the potential use of this antioxidant as a nutraceutical (tested both ex vivo and in vivo) will be discussed.

Association of plasma neutrophil elastase levels with other inflammatory mediators and clinical features in adult patients with moderate and severe pneumonia

BACKGROUND

Plasma levels of neutrophil elastase (NE) are elevated in several inflammatory diseases and thus this enzyme might be a critical inflammatory marker. However, the role of NE in the pathogenesis of pneumonia has not been determined. The association between the severity of pneumonia and blood levels of inflammatory markers could be relevant to developing a useful indicator of severity and new therapeutic strategies for pneumonia.

METHODS

We searched for a useful predictive marker and a new therapeutic strategy against pneumonia, using a prospective, multicenter, population-based investigation. Several inflammatory markers in the circulation including NE, cytokines, defensins, C-reactive protein (CRP) and white blood cell (WBC) counts as well as clinical features were prospectively monitored in 28 adult patients with moderate (n=11) and severe pneumonia (n=17) over a period of 14 days.

RESULTS

The value of plasma NE was the highest at entry and significantly declined 2 days later. Trends of cytokines, defensins, CRP and WBC counts were similar but blunter. Microorganisms and the outcome of initial treatment did not significantly affect plasma NE levels. Baseline values of plasma NE were significantly higher in severe, than in moderate pneumonia and this difference between the two types of pneumonia persisted longer than those of any other markers.

CONCLUSIONS

Neutrophil elastase appears to play a critical role in severe pneumonia and determination of its concentration in blood could be a useful indicator of severity. Furthermore, clinical trials of anti-NE drugs in patients with severe pneumonia should be promising.

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

OBJECTIVE

N-acetylcysteine, a potent anti-inflammatory and antioxidant agent, is known to decrease the production of reactive oxygen species after cardiac surgery. The objective of this study was to evaluate the effects of intravenous N-acetylcysteine on clinical and biochemical outcomes after coronary artery bypass surgery with cardiopulmonary bypass.

METHODS

One hundred patients (mean age 60.5 years, range 43-78 years, 89% male) undergoing coronary artery bypass grafting at the Montreal Heart Institute were randomized to receive either N-acetylcysteine (600 mg orally the day before and the morning of the operation, a bolus of 150 mg/kg of intravenous N-acetylcysteine before skin incision, followed by perfusion at 12.5 mg x kg(-1) x h(-1) over 24 hours; n = 50) or placebo (n = 50). The patients and clinical team were blinded to group assignments. Preoperative characteristics were similar between the two groups. Postoperative clinical data (death, myocardial infarction, low-output syndromes, arrhythmias, bleeding, transfusion requirements, and intensive care unit and hospital lengths of stay) and biochemical markers (creatine kinase MB, troponin T, creatinine, hemoglobin, and platelet levels) were evaluated serially over 4 days.

RESULTS

Clinical outcomes were not significantly different between the two groups with regard to the incidence of death, myocardial infarction, bleeding, transfusion requirements, intubation time, and hospital length of stay. No differences were found in postoperative biochemical markers (troponin T, creatine kinase MB, creatinine, hemoglobin, and platelets) between the groups. No differences were observed between the groups in interleukin-6 production (P = not significant).

CONCLUSIONS

Prophylactic use of N-acetylcysteine in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass does not lead to improvement in clinical results or biochemical markers. Further strategies to decrease reperfusion injury should be devised.

Modulation of systemic inflammatory response after cardiac surgery

Cardiac surgery and cardiopulmonary bypass initiate a systemic inflammatory response largely determined by blood contact with foreign surfaces and the activation of complement. It is generally accepted that cardiopulmonary bypass initiates a whole-body inflammatory reaction. The magnitude of this inflammatory reaction varies, but the persistence of any degree of inflammation may be considered potentially harmful to the cardiac patient. The development of strategies to control the inflammatory response following cardiac surgery is currently the focus of considerable research efforts. Diverse techniques including maintenance of hemodynamic stability, minimization of exposure to cardiopulmonary bypass circuitry, and pharmacologic and immunomodulatory agents have been examined in clinical studies. This article briefly reviews the current concepts of the systemic inflammatory response following cardiac surgery, and the various therapeutic strategies being used to modulate this response.

Antioxidant and anti-inflammatory efficacy of NAC in the treatment of COPD: discordant in vitro and in vivo dose-effects: a review

In order to develop efficient therapeutic regimes for chronic obstructive pulmonary disease (COPD), N-acetylcysteine (NAC) has been tested as a medication which can suppress various pathogenic processes in this disease. Besides its well-known and efficient mucolytic action, NAC meets these needs by virtue of its antioxidant and anti-inflammatory modes of action. NAC is a thiol compound which by providing sulfhydryl groups, can act both as a precursor of reduced glutathione and as a direct ROS scavenger, hence regulating the redox status in the cells. In this way it can interfere with several signaling pathways that play a role in regulating apoptosis, angiogenesis, cell growth and arrest and inflammatory response. Overall, the antioxidant effects of NAC are well documented in in vivo and in vitro studies. It successfully inhibits oxidative stress at both high and low concentrations, under acute (in vitro) and chronic administration (in vivo). With regard to its anti-inflammatory action, in contrast, the effects of NAC differ in vivo and in vitro and are highly dose-dependent. In the in vitro settings anti-inflammatory effects are seen at high but not at low concentrations. On the other hand, some long-term effectiveness is reported in several in vivo studies even at low dosages. Increasing the dose seems to improve NAC bioavailability and may also consolidate some of its effects. In this way, the effects that are observed in the clinical and in vivo studies do not always reflect the success of the in vitro experiments. Furthermore, the results obtained with healthy volunteers do not always provide incontrovertible proof of its usefulness in COPD especially when number of exacerbations and changes in lung function are chosen as the primary outcomes. Despite these considerations and in view of the present lack of effective therapies to inhibit disease progression in COPD, NAC and its derivatives, because of their multiple molecular modes of action, remain promising medication once doses and route of administration are optimized.

Cytokine-Dependent Proliferation of Human CD34+Progenitor Cells in the Absence of Serum Is Suppressed by Their Progeny's Production of Serine Proteinases

In this study, we demonstrate that the synthesis and release of serine proteinases by hematopoietic cells affects the in vitro proliferation of hematopoietic progenitor cells (HPCs) in response to proteins, including hematopoietic growth factors (HGFs), transferrin, insulin, and albumin in serum-free cultures. In serum-free cultures, bone marrow mononuclear cells or the CD34- progeny of the CD34+ cells were shown to release the serine proteinases human neutrophil elastase (HNE), cathepsin G (Cath G), and proteinase 3 (Pr3). In the absence of serum, we showed that HNE, Cath G, and Pr3 rapidly and dose-dependently degraded HGF and other proteins present in the medium, resulting in decreased proliferation of HPCs. Addition of the serine proteinase inhibitors alpha1-proteinase inhibitor (alpha1-PI) or the secretory leukocyte proteinase inhibitor (SLPI), but not leupeptin, aprotinin, or AEBSF (4-[2-aminoethyl]-benzenesulfonylfluoride hydrochloride), could completely prevent the degradation of proteins relevant to the growth of hematopoietic cells. Thus, the addition of serine proteinase inhibitors like alpha1-PI or SLPI may be critical for the expansion of CD34+ cells or gene transfer into CD34+ cells or other hematopoietic cells in vitro using serum-free media under good manufacturing practice conditions.

Effects of N-acetylcysteine on acute necrotizing pancreatitis in rats

The aim of this study was to investigate the influence of N-acetylcysteine (NAC) on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. The induction of ANP resulted in significant increase in mortality rate, pancreatic necrosis and serum activity of amylase, alanine aspartate transferase (ALT), interleukin-6 (IL-6), lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, serum concentration of urea, tissue activity of myeloperoxidase (MPO) and malondialdehyde (MDA) in the pancreas and lung, and significant decrease of concentrations of calcium, blood pressure, urine output and pO(2). The use of NAC inhibited the changes in urine output, pO(2), tissue activity of MPO and MDA in pancreas and lungs, and the serum activity of IL-6, ALT, and serum concentrations of urea and calcium. NAC reduced the mortality and pancreatic damage. The use of NAC has a beneficial effect on the course of ANP in rats. It may be used in the treatment of acute pancreatitis.

Oxidative stress precedes peak systemic inflammatory response in pediatric patients undergoing cardiopulmonary bypass operation

Oxidative stress seems to contribute to cardiopulmonary bypass (CPB)-related postoperative complications. Pediatric patients are particularly prone to these complications. With this in mind, we measured oxidative stress markers in blood plasma of 20 children undergoing elective heart surgery before, during, and up to 48 h after cessation of CPB, along with inflammatory parameters and full analysis of iron status. Ascorbate levels were decreased by approximately 50% (P < 0.001) at the time of aorta cross-clamp removal (or pump switch-off in 4 patients with partial CPB), and associated with corresponding increases in dehydroascorbate (P < 0.001, r = -0.80) and malondialdehyde (P < 0.01, r = -0.59). In contrast to the immediate oxidative response, peak levels of IL-6 and IL-8 were not observed until 3-12 h after CPB cessation. The early loss of ascorbate correlated with duration of CPB (P < 0.002, r = 0.72), plasma hemoglobin after cross-clamp removal (P < 0.001, r = 0.70), and IL-6 and IL-8 levels at 24 and 48 h after CPB (P < 0.01), but not with postoperative lactate levels, strongly suggesting that hemolysis, and not inflammation or ischemia, was the main cause of early oxidative stress. The correlation of ventilation time with early changes in ascorbate (P < 0.02, r = 0.55), plasma hemoglobin (P < 0.01, r = 0.60), and malondialdehyde (P < 0.02, r = 0.54) suggests that hemolysis-induced oxidative stress may be an underlying cause of CPB-associated pulmonary dysfunction. Optimization of surgical procedures or therapeutic intervention that minimize hemolysis (e.g., off-pump surgery) or the resultant oxidative stress (e.g., antioxidant treatment) should be considered as possible strategies to lower the rate of postoperative complications in pediatric CPB.

Effects of N-acetylcysteine on pulmonary function in patients undergoing coronary artery bypass surgery with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has been implicated in causing poor pulmonary gas exchange postoperatively in patients undergoing coronary artery bypass grafting (CABG) procedures. In this prospective, randomized, double-blind, placebo-controlled study, we examined the pulmonary effects of N-acetylcysteine (NAC) in patients undergoing CABG. Twenty patients undergoing elective CABG and early tracheal extubation were randomized into two groups. Group I (ten patients) received a physiologic salt solution as a placebo in a continuous intravenous infusion for one hour before CPB and 24 hours after CPB; Group II (ten patients) received 100 mg/ kg NAC intravenously for one hour before CPB and 40 mg/kg/day at 24 hours after CPB. Perioperative hemodynamic and pulmonary data were recorded. Postoperative tracheal extubation was accomplished at the earliest appropriate time. The postoperative clinical course was similar in the two groups. Both groups exhibited significant postoperative increases in A-a oxygen gradient (p < 0.01), but patients in Group II exhibited significantly lower increases in postoperative A-a oxygen gradient (p < 0.006). Other hemodynamic and pulmonary data (pulmonary capillary wedge pressure, pulmonary vascular resistance (PVR), cardiac index (CI), shunt flow, dynamic lung compliance and static lung compliance) exhibited no differences between the groups. There was no significant difference in terms of intubation time. The malondialdehyde (MDA) increase in Group II following CPB was found to be significantly lower than in Group I (p = 0.043). This clinical study reveals that administration of NAC to patients undergoing elective CABG with CPB improves systemic oxygenation. There was no effect in other pulmonary parameters and in terms of intubation time.

Lack of effect of prophylactic N-acetylcysteine on postoperative organ dysfunction following major abdominal tumour surgery: a randomized, placebo-controlled, double-blinded clinical trial

Sepsis and respiratory dysfunction leading to multiple system organ failure remains the leading cause of postoperative morbidity and mortality following major surgical procedures. It has been suggested the oxygen free radicals might play a pivotal role in this process. The aim of this study was to investigate whether short-term infusion of N-acetylcysteine (N-acetylcysteine), a potent antioxidant, administered before and during extensive abdominal surgery, could ameliorate the progression of early postoperative organ dysfunction and improve oxygenation. Out of the 93 patients, 47 received N-acetylcysteine and 46 were given placebo in a randomized, controlled, double-blinded fashion. Patients received N-acetylcysteine (150 mg.kg-1 bolus followed by a continuous infusion of 12 mg.kg-1.h-1) or the same volume of placebo (5% dextrose) during surgery. Treatment effect on organ function was assessed by organ dysfunction scores according to physiological parameters of six main organ systems: respiratory, cardiovascular, renal, hepatic, haematological and central nervous system. The scores were obtained on admission, then daily during the first three postoperative days. For statistical analysis Mann-Whitney U and Chi-squared tests were used. There was no significant difference between the two groups in any of the six organ dysfunction parameters, length of intensive care stay, days of mechanical ventilation and mortality. Our results do not support the routine use of N-acetylcysteine as a prophylactic measure during surgery, and reinforce previous evidence which challenges the indication of N-acetylcysteine in the critically ill.

The side-effects of cardiopulmonary bypass on the lungs: changes in bronchoalveolar lavage fluids

Although technical refinements have improved the safety of cardiac operations, postoperative dysfunction of lung and other organs occurs frequently after cardiopulmonary bypass (CPB). The aim of the present study was to search the aetiopathogenesis of pulmonary complications due to CBP. Ten patients with stable coronary artery disease, undergoing coronary artery bypass grafting (CABG) surgery, were included in the study. Forty bronchoalveolar lavage (BAL) fluid samplings were performed in the 10 patients. Samples were obtained at the following time periods: (1) preoperatively; (2) at the end of the first hour after anaesthetic induction; (3) at the conclusion of 30 min of crossclamp on CPB; and (4) at the conclusion of 20 h after the end of CPB, postoperatively. Cell contents of bronchoalveolar lavage fluid, alveolar macrophage viability, eosinophil cationic protein (ECP) levels and myeloperoxidase (MPO) concentrations were analysed in each bronchoalveolar lavage fluids. While the percentage of preoperative macrophages was 85.90% and the percentage of preoperative neutrophils was 2.40%, they were 77.00% and 11.30% in the postoperative samples, respectively. Mean alveolar macrophage viability was 96.20% preoperatively and 90.40% in the postoperative period. Preoperative eosinophil cationic protein mean concentration was < 2 microg/l and mean response value (RV) was 28.80. Preoperative mean myeloperoxidase concentration was 7.66 ng/ml. Postoperative eosinophil cationic protein mean response value was 63.40 and mean myeloperoxidase concentration was 59.25 ng/ml. There were significant differences between third and final samples with regard to both neutrophil percentages (p = 0.028) and MPO levels (p = 0.005). While the preoperative mean PaO2 value was 89.39 mmHg and mean SaO2 value was 97.12%, they were calculated in the postoperative arterial blood specimens of patients, without inhaling O2, as 65.31 mmHg and 93.84%. These changes between blood gas analyses reflect the impairment of the lungs (p = 0.009 and p = 0.007, respectively). Neither alveolar macrophage viability nor ECP levels changed significantly between consecutive periods. However, when the results of the first and fourth samples were compared, we saw the cumulative effects of CPB, in that alveolar macrophages lost their viability and ECP mean RVs rose. These changes were statistically significant (p = 0.027 and p = 0.013, respectively). However, postoperative ECP levels were not like those found in a patient with asthma. Also, changes between alveolar macrophage percentages (p = 0.028), between neutrophil percentages (p = 0.036) and between MPO concentrations (p = 0.005) were statistically significant. Again, changes in neutrophil percentages between first and final samples correlated with changes in MPO levels between same periods (r = 0.657, p = 0.039).

N-Acetylcysteine treatment to prevent the progression of multisystem organ failure: a prospective, randomized, placebo-controlled study

OBJECTIVES

To investigate whether prolonged infusion of N-acetylcysteine (NAC) that is commenced immediately after admission to the intensive care unit could ameliorate the development or progression of multisystem organ failure and improve mortality.

DESIGN

Prospective, randomized, double-blinded clinical trial.

SETTING

Six-bed intensive care unit in a teaching hospital.

PATIENTS

Of the 100 patients recruited (14 withdrew), 86 patients were studied.

INTERVENTIONS

After randomization, the treatment group (n = 41) received NAC (150 mg/kg bolus followed by a continuous infusion of 12 mg/kg/hr) and the placebo group (n = 45) received 5% dextrose, from a minimum of 3 days up to a maximum of 5 days.

MEASUREMENTS AND MAIN RESULTS

There was no statistically significant difference between the two groups regarding outcome as indicated by mortality and the required days of inotropic support, mechanical ventilation, and intensive care. The time interval between hospital and intensive care unit admission showed great variability, with a median of 24 hrs for the whole sample. By splitting the groups with this median value, the effect of NAC was examined on patients admitted within 24 hrs and after 24 hrs of arrival to the hospital. There was a nonsignificant difference in mortality in favor of NAC. Patients admitted after 24 hrs of hospital admission had a significantly worse mortality in the NAC-treated group (61% vs. 32% for controls; p = .05).

CONCLUSIONS

We found a nonsignificant difference in outcome between NAC and placebo-treated patients. Our results suggest that the initiation of NAC treatment >24 hrs after hospital admission may potentially be harmful, and further studies should be undertaken to investigate the clinical use of the early application of NAC in critically ill patients.

Lesão pulmonar de reperfusão

A lesão de isquemia-reperfusão constitui-se em um evento fisiopatológico comum a diversas doenças da prática clínica diária. O pulmão pode ser alvo da lesão de isquemia-reperfusão diretamente, como no edema pulmonar após transplante ou na resolução de tromboembolismo; ou ainda ser atingido à distância, como nos casos de choque ou por lesão de reperfusão em intestino ou em membros inferiores, como ocorre no pinçamento da aorta, utilizado nas cirurgias de aneurisma. Dentre os mediadores envolvidos na lesão de isquemia-reperfusão, foram identificados espécies reativas tóxicas de oxigênio (ERTO), mediadores lipídicos, como a tromboxana, moléculas de adesão em neutrófilos e endotélio, fator de necrose tumoral, dentre outros. As medidas terapêuticas para a lesão de reperfusão ainda são utilizadas no plano experimental e em poucos estudos clínicos. São utilizados: antioxidantes, bloqueadores de mediadores lipídicos, inibidores da interação entre leucócito e endotélio ou substâncias que favoreçam o fluxo sanguíneo pós-isquêmico.

Does N-acetyl-L-cysteine influence cytokine response during early human septic shock?

STUDY OBJECTIVE

To assess the effects of adjunctive treatment with N-acetyl-L-cysteine (NAC) on hemodynamics, oxygen transport variables, and plasma levels of cytokines in patients with septic shock.

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

A 24-bed medicosurgical ICU in a university hospital.

PATIENTS

Twenty-two patients included within 4 h of diagnosis of septic shock.

INTERVENTIONS

Patients were randomly allocated to receive either NAC (150 mg/kg bolus, followed by a continuous infusion of 50 mg/kg over 4 h; n= 12) or placebo (n=10) in addition to standard therapy.

MEASUREMENTS

Plasma concentrations of tumor necrosis factor-alpha (TNF), interleukin (IL)-6, IL-8, IL-10, and soluble tumor necrosis factor-alpha receptor-p55 (sTNFR-p55) were measured by sensitive immunoassays at 0, 2, 4, 6 and 24 h. Pulmonary artery catheter-derived hemodynamics, blood gases, hemoglobin, and arterial lactate were measured at baseline, after infusion (4 h), and at 24 h.

RESULTS

NAC improved oxygenation (PaO2/FIO2 ratio, 214+/-97 vs 123+/-86; p<0.05) and static lung compliance (44+/-11 vs 31+/-6 L/cm H2O; p<0.05) at 24 h. NAC had no significant effects on plasma TNF, IL-6, or IL-10 levels, but acutely decreased IL-8 and sTNFR-p55 levels. The administration of NAC had no significant effect on systemic and pulmonary hemodynamics, oxygen delivery, and oxygen consumption. Mortality was similar in both groups (control, 40%; NAC, 42%) but survivors who received NAC had shorter ventilator requirement (7+/-2 days vs 20+/-7 days; p<0.05) and were discharged earlier from the ICU (13+/-2 days vs 32+/-9 days; p<0.05).

CONCLUSION

In this small cohort of patients with early septic shock, short-term IV infusion of NAC was well-tolerated, improved respiratory function, and shortened ICU stay in survivors. The attenuated production of IL-8, a potential mediator of septic lung injury, may have contributed to the lung-protective effects of NAC.

The balance of pro- and anti-inflammatory cytokines in cardiac surgery

Homeostatic control of the balance of pro- and anti-inflammatory cytokines is important for the maintenance of health. Cardiac surgery, with its intense pro-inflammatory stimulus, constitutes a major challenge to the patient's ability to maintain this balance. Pre- and intraoperative factors influencing the maintenance of cytokine balance are discussed.