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BACKGROUND: Oxidative damage to the ovaries is the primary cause of impaired reproductive functions in female animals. This study aimed to investigate the protective role of N-Acetyl-L-cysteine (NAC) in reducing oxidative damage in the ovaries of female rabbits. METHODS AND RESULTS: Female rabbit ovaries were treated in vitro with varying concentrations of D-galactose (D-gal): 0, 5, 10, and 15 mg/mL, and it was found that 10 mg/mL D-gal significantly disrupted follicular structures, causing disarray in granulosa cell arrangements and significantly reducing T-SOD and GSH levels (p < 0.01). Consequently, we selected 10 mg/mL D-gal to establish an ovarian failure model. These models were treated with multiple doses of NAC (0, 0.1, 0.3, 0.5 mg/mL). The results revealed that the disruption in granulosa cell arrangement caused by 10 mg/mL D-gal was effectively alleviated by 0.1 mg/mL NAC compared to the D-gal treatment group. Furthermore, 10 mg/mL D-gal significantly (p < 0.01) reduced GSH, T-SOD, and catalase (CAT) levels in the ovaries. However, 0.1 mg/mL NAC effectively (p < 0.01) suppressed these adverse effects. Moreover, the current results showed that 10 mg/mL D-gal alone significantly (p < 0.01) downregulated the expression of Nrf2, GPX, PRDX4, GSR, SOD1, and TAF4B, whereas 0.1 mg/mL NAC counteracted these suppressive effects (p < 0.01). CONCLUSIONS: It could be concluded that NAC may delay ovarian failure by reducing D-gal-induced ovarian oxidative damage in female rabbit, suggested NAC could be a promising therapeutic agent for protecting against ovarian failure and potentially delaying ovarian failure in female rabbits.

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Reactive oxygen species (ROS) play a significant role in toxicity to the retina in a variety of diseases. N-acetylcysteine (NAC), N-acetylcysteine amide (NACA) and the dimeric di-N-acetylcysteine amide (diNACA) were evaluated in terms of protecting retinal cells, in vitro, in a variety of stress models. Three types of rat retinal cell cultures were utilized in the study: macroglial-only cell cultures, neuron-only retinal ganglion cell (RGC) cultures, and mixed cultures containing retinal glia and neurons. Ability of test agents to attenuate oxidative stress in all cultures was ascertained. In addition, capability of agents to protect against a variety of alternate clinically-relevant stressors, including excitotoxins and mitochondrial electron transport chain inhibitors, was also evaluated. Capacity of test agents to elevate cellular levels of reduced glutathione under normal and compromised conditions was also determined. NAC, NACA and diNACA demonstrated concentration-dependent cytoprotection against oxidative stress in all cultures. These three compounds, however, had differing effects against a variety of alternate insults to retinal cells. The most protective agent was NACA, which was most potent against the most stressors (including oxidative stress, mitochondrial impairment by antimycin A and azide, and glutamate-induced excitotoxicity). Similar to NAC, NACA increased glutathione levels in non-injured cells, although diNACA did not, suggesting a different, unknown mechanism of antioxidant activity for the latter. In support of this, diNACA was the only agent to attenuate rotenone-induced toxicity in mitochondria. NAC, NACA and diNACA exhibited varying degrees of antioxidant activity, i.e., protected cultured rat retinal cells from a variety of stressors which were designed to mimic aspects of the pathology of different retinal diseases. A general rank order of activity was observed: NACA ≥ diNACA > NAC. These results warrant further exploration of NACA and diNACA as antioxidant therapeutics for the treatment of retinal diseases, particularly those involving oxidative stress. Furthermore, we have defined the battery of tests carried out as the "Wood, Chidlow, Wall and Casson (WCWC) Retinal Antioxidant Indices"; we believe that these are of great value for screening molecules for potential to reduce retinal oxidative stress in a range of retinal diseases.

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Background: Drug-induced adverse symptoms affect patients' quality of life (QoL) during treatment. Understanding the underlying mechanisms of drug-induced adverse effects could help prevent them. As current drugs have limited effects in halting the progress of Alzheimer's disease (AD), patients are required to take these drugs over a long period. The main obstacles to long-term compliance are drug-elicited side effects that deteriorate patient QoL. Objective: Donepezil, the most popular acetylcholinesterase inhibitor (AChEI) drug for AD, induces various side effects, especially at high doses. This study aimed to identify a drug that can attenuate the side effects of donepezil and investigate the underlying mechanisms. Methods: Five-week-old Sprague-Dawley rats received daily oral donepezil and N-acetylcysteine (NAC) for four weeks. General symptoms following administration were monitored daily to address drug-related adverse effects. Cytosolic calcium influx and generation of reactive oxygen species (ROS) after drug treatment were measured in vitro using C2C12 myotubes. Results: High-dose donepezil induced numerous adverse symptoms in male and female rats, which were markedly attenuated by co-treatment with NAC. NAC significantly reduced both acute and chronic muscle-related symptoms caused by donepezil. Additionally, in vitro studies showed that high-dose donepezil increased ROS and intracellular calcium ([Ca2 +]i) levels in muscle cells, contributing to these adverse effects. NAC co-treatment dramatically reduced ROS and [Ca2 +]i levels in muscle cells. Conclusions: Combined treatment with NAC effectively diminishes the adverse effects elicited by donepezil by regulating ROS and [Ca2 +]i levels in the skeletal muscle, which could contribute to improving donepezil treatment in patients.

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Bacterial resistance poses a significant threat to both human and animal health. N-acetylcysteine (NAC), which is used as an anti-inflammatory, has been shown to have distinct and contrasting impacts on bacterial resistance. However, the precise mechanism underlying the relationship between NAC and bacterial resistance remains unclear and requires further investigation. In this study, we study the effect of NAC on bacterial resistance and the underlying mechanisms. Specifically, we examine the effects of NAC on Edwardsiella tarda ATCC15947, a pathogen that exhibits resistance to many antibiotics. We find that NAC can promote resistance of E. tarda to many antibiotics, such as doxycycline, resulting in an increase in the bacterial survival rate. Through proteomic analysis, we demonstrate that NAC activates the amino acid metabolism pathway in E. tarda, leading to elevated intracellular glutathione (GSH) levels and reduced reactive oxygen species (ROS). Additionally, NAC reduces antibiotic influx while enhancing efflux, thus maintaining low intracellular antibiotic concentrations. We also propose that NAC promotes protein aggregation, thus contributing to antibiotic resistance. Our study describes the mechanism underlying E. tarda resistance to doxycycline and cautions against the indiscriminate use of metabolite adjuvants.

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Background: N-acetyl cysteine (NAC) appears promising as a treatment in patients with substance use disorder (SUD) as it helps rebalance glutamate levels in the central nervous system (CNS). Basal concentrations of glutamate are indeed reduced in SUD patients but increased during craving. Materials and Methods: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs). We assessed whether NAC reduce craving rating as compared to a placebo in SUD patients. Secondary outcomes were withdrawal symptoms (WS), side effects (SE) and drop-outs. Estimates are presented as standardized mean differences (SMD) or risk ratio (RR) with 95% confidence interval (CI). Results: Eleven RCTs were included. NAC reduced craving rating (SMD -0.61 (-1.17, -0.06), p = 0.03, I2 = 85%), with no differences in the subgroup analysis according to the drug addiction (alcohol, cocaine, poly-drugs, amphetamine, nicotine) (p = 0.98). Among the secondary outcomes, for WS data showed no significant difference between groups (SMD -0.18 (-0.43, 0.08), p = 0.17); for SE no substantial difference was observed between the two treatment groups (RR = 1.06 (0.89-1.27), p = 0.52, I2 = 0%); for dropouts the results are in favor of the placebo but no statistically significant (RR 1.17 (0.85, 1.61), p = 0.34; I2 = 0%). Conclusion: NAC seem to reduce craving rating in SUD patients, but evidence is weak. More studies are needed to confirm this finding.

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Endometrial cancer (EC) is one of the most common gynecologic malignancies, which lacking effective drugs for intractable conditions or patients unsuitable for surgeries. Recently, the patient-derived organoids (PDOs) are found feasible for cancer research and drug discoveries. Here, we have successfully established a panel of PDOs from EC and conducted drug repurposing screening and mechanism analysis for cancer treatment. We confirmed that the regulatory ß subunit of methionine adenosyltransferase (MAT2B) is highly correlated with malignant progression in endometrial cancer. Through drug screening on PDOs, we identify JX24120, chlorpromazine derivative, as a specific inhibitor for MAT2B, which directly binds to MAT2B (Kd = 4.724 µM) and inhibits the viability of EC PDOs and canonical cell lines. Correspondingly, gene editing assessment demonstrates that JX24120 suppresses tumor growth depending on the presence of MAT2B in vivo and in vitro. Mechanistically, JX24120 induces inhibition of S-adenosylmethionine (SAMe) synthesis, leading to suppressed mTORC1 signaling, abnormal energy metabolism and protein synthesis, and eventually apoptosis. Taken together, our study offers a novel approach for drug discovery and efficacy assessment by using the PDOs models. These findings suggest that JX24120 may be a potent MAT2B inhibitor and will hopefully serve as a prospective compound for endometrial cancer therapy.

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Background: Oxidative stress-induced mitochondrial damage is the major cause of cardiomyocyte dysfunction. Therefore, the maintenance of mitochondrial function, which is regulated by mitochondrial quality control (MQC), is necessary for cardiomyocyte homeostasis. This study aimed to explore the underlying mechanisms of N-acetylcysteine (NAC) function and its relationship with MQC. Methods: A hydrogen peroxide-induced oxidative stress model was established using H9c2 cardiomyocytes treated with or without NAC prior to oxidative stress stimulation. Autophagy with light chain 3 (LC3)-green fluorescent protein (GFP) assay, reactive oxygen species (ROS) with the 2',7'-dichlorodi hydrofluorescein diacetate (DCFH-DA) fluorescent, lactate dehydrogenase (LDH) release assay, adenosine triphosphate (ATP) content assay, and a mitochondrial membrane potential detection were used to evaluate mitochondrial dynamics in H2O2-treated H9c2 cardiomyocytes, with a focus on the involvement of MQC regulated by NAC. Cell apoptosis was analyzed using caspase-3 activity assay and Annexin V-fluorescein isothiocyanate (V-FITC)/propidium iodide (PI) double staining. Results: We observed that NAC improved cell viability, reduced ROS levels, and partially restored optic atrophy 1 (OPA1) protein expression under oxidative stress. Following transfection with a specific OPA1-small interfering RNA, the mitophagy, mitochondrial dynamics, mitochondrial functions, and cardiomyocyte apoptosis were evaluated to further explore the mechanisms of NAC. Our results demonstrated that NAC attenuated cardiomyocyte apoptosis via the ROS/OPA1 axis and protected against oxidative stress-induced mitochondrial damage via the regulation of OPA1-mediated MQC. Conclusions: NAC ameliorated the injury to H9c2 cardiomyocytes caused by H2O2 by promoting the expression of OPA1, consequently improving mitochondrial function and decreasing apoptosis.

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PURPOSE: We assessed the potential association between N-acetyl-cysteine (NAC) and clinical outcomes in critically ill subjects with COVID-19-related ARDS. MATERIAL AND METHODS: We included subjects with confirmed COVID-19 who were admitted to our ICU between March 1, 2020, and January 31, 2021, due to ARDS and necessitating invasive mechanical ventilation (IMV). Subjects who received standard of care (SOC) were compared with subjects who additionally received NAC 600 mg bid orally. RESULTS: A total of 243 subjects were included in this study. The results indicate significantly improved survival rates in the NAC plus SOC group, both in the unadjusted analysis and after adjusting for confounding factors such as ARDS severity (HR 0.48, 95% CI 0.32-0.70). CONCLUSIONS: We found that oral administration of NAC was associated with reduced mortality in critically ill patients with COVID-19 related ARDS.

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The matrix of extracellular polymeric substances (EPS) present in biofilms greatly amplifies the problem of bacterial infections, protecting bacteria against antimicrobial treatments and eventually leading to bacterial resistance. The need for alternative treatments that destroy the EPS matrix becomes evident. N-acetylcysteine (NAC) is one option that presents diverse effects against bacteria; however, the different mechanisms of action of NAC in biofilms have yet to be elucidated. In this work, we performed microscopy studies at micro and nano scales to address the effects of NAC at single cell level and early-stage biofilms of the Xylella fastidiosa phytopathogen. We show the physical effects of NAC on the adhesion surface and the different types of EPS, as well as the mechanical response of individual bacteria to NAC concentrations between 2 and 20 mg/mL. NAC modified the conditioning film on the substrate, broke down the soluble EPS, resulting in the release of adherent bacteria, decreased the volume of loosely bound EPS, and disrupted the biofilm matrix. Tightly bound EPS suffered structural alterations despite no solid evidence of its removal. In addition, bacterial force measurements upon NAC action performed with InP nanowire arrays showed an enhanced momentum transfer to the nanowires due to increased cell mobility resulting from EPS removal. Our results clearly show that conditioning film and soluble EPS play a key role in cell adhesion control and that NAC alters EPS structure, providing solid evidence that NAC actuates mainly on EPS removal, both at single cell and biofilm levels.

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Nausea serves as a protective mechanism in organisms to prevent excessive consumption of toxic substances. Due to the adverse effects of chemical anti-nausea drugs, there is a growing interest in using herbal remedies and natural antioxidants. In this study, we evaluated the neuroprotective effects of quercetin (QU) and N-acetylcysteine (NAC) against oxidative damage induced by nausea. Emesis was induced in chickens using ipecac and copper sulfate (600 and 60 mg/kg, orally, respectively). QU and NAC (with doses of 50, 100, 200 mg/kg), and their combination were administered, along with a standard therapy (metoclopramide; MET 2 mg/kg) for one-time. Mitochondrial function, lipid peroxidation (LPO), protein carbonyl (PC), glutathione level (GSH), and reactive oxygen species (ROS) as oxidative damage biomarkers were evaluated in the chicken's brain mitochondria. QU and NAC significantly reduced emesis induced by copper sulfate and ipecac compared to the control group (P < 0.001). Significant differences in oxidative damage were observed in the groups received of copper sulfate and ipecac compared with control group. Levels of LPO, ROS, and PC were significantly decreased after the administration of QU and NAC in emesis induced by copper sulfate and ipecac. While, mitochondrial function and GSH levels were increased after the administration of QU and NAC. Combination therapy with QU and NAC yielded the most effective results. This study suggests that QU and NAC possess antiemetic effects through both peripheral and central mechanisms and exhibit neuroprotective effects against oxidative brain damage induced by emesis by increasing plasma antioxidants or scavenging free radicals.

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Background: Radiation-induced heart disease (RIHD) is a serious complication of thoracic tumor radiotherapy that substantially affects the quality of life of cancer patients. Oxidative stress plays a pivotal role in the occurrence and progression of RIHD, which prompted our investigation of an innovative approach for treating RIHD using antioxidant therapy. Methods: We used 8-week-old male Sprague-Dawley (SD) rats as experimental animals and H9C2 cells as experimental cells. N-acetylcysteine (NAC) was used as an antioxidant to treat H9C2 cells after X-ray irradiation in this study. In the present study, the extent of cardiomyocyte damage caused by X-ray exposure was determined, alterations in oxidation/antioxidation levels were assessed, and changes in the expression of genes related to mitochondria were examined. The degree of myocardial tissue and cell injury was also determined. Dihydroethidium (DHE) staining, reactive oxygen species (ROS) assays, and glutathione (GSH) and manganese superoxide dismutase (Mn-SOD) assays were used to assess cell oxidation/antioxidation. Flow cytometry was used to determine the mitochondrial membrane potential and mitochondrial permeability transition pore (mPTP) opening. High-throughput transcriptome sequencing and bioinformatics analysis were used to elucidate the expression of mitochondria-related genes in myocardial tissue induced by X-ray exposure. Polymerase chain reaction (PCR) was used to verify the expression of differentially expressed genes. Results: X-ray irradiation damaged myocardial tissue and cells, resulting in an imbalance of oxidative and antioxidant substances and mitochondrial damage. NAC treatment increased cell counting kit-8 (CCK-8) levels (P=0.02) and decreased lactate dehydrogenase (LDH) release (P=0.02) in cardiomyocytes. It also reduced the level of ROS (P=0.002) and increased the levels of GSH (P=0.04) and Mn-SOD (P=0.01). The mitochondrial membrane potential was restored (P<0.001), and mPTP opening was inhibited (P<0.001). Transcriptome sequencing and subsequent validation analyses revealed a decrease in the expression of mitochondria-related genes in myocardial tissue induced by X-ray exposure, but antioxidant therapy did not reverse the related DNA damage. Conclusions: Antioxidants mitigated radiation-induced myocardial damage to a certain degree, but these agents did not reverse the associated DNA damage. These findings provide a new direction for future investigations by our research group, including exploring the treatment of RIHD-related DNA damage.

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BACKGROUND: Phlegm is prevalent symptom in patients with chronic obstructive pulmonary disease (COPD). Few studies have investigated the effectiveness of N-acetylcysteine (NAC) nebulizer therapy in COPD patients. We evaluated the effect of nebulized NAC on the improvement of phlegm symptom in COPD patients. METHODS: This was a 12-week, prospective, single-arm, open-label, phase IV multi-center trial (NCT05102305, Registration Date: 20-October-2021). We enrolled patients aged ≥ 40 years with post bronchodilator forced expiratory volume in one second/forced vital capacity (FEV1/FVC) < 0.7 and COPD assessment test (CAT) phlegm score ≥ 2; the patients were current or ex-smoker with smoking pack-years ≥ 10. The primary endpoint was to determine the change in CAT phlegm score at 12 weeks compared to the baseline. Patients were assessed at baseline, 4, 8, and 12 weeks of treatment using the CAT score. RESULTS: In total, 100 COPD patients were enrolled from 10 hospitals. The mean age of the patients was 71.42 ± 8.20 years, with 19.78% being current-smokers and 80.22% being ex-smokers. The mean smoking pack-years was 40.32 ± 35.18. The mean FVC, FEV1, and FEV1/FVC were 3.94 L (75.44%), 2.22 L (58.50%), and 0.53, respectively. The CAT phlegm score at baseline was 3.47 ± 1.06, whereas after 12 weeks of nebulized NAC it significantly decreased to 2.62 ± 1.30 (p < 0.01). More than half (53.5%) of the patients expressed satisfaction with the effects of nebulized NAC therapy. Adverse events occurred in 8 (8.0%) patients. Notably, no serious adverse drug reactions were reported. CONCLUSION: In this study, we have established the effectiveness and safety of nebulized NAC over 12 weeks.

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N-acetylcysteine (NAC) is known for its beneficial effects on health due to its antioxidant and antiapoptotic properties. This study explored the protective effects of NAC against oxidative stress in heat-stressed (HS) skeletal muscle cells and its role in promoting muscle development. NAC reduced the heat shock response by decreasing the expression of heat shock protein 70 (HSP70) in HS-induced muscle cells during proliferation and differentiation. NAC also mitigated HS-induced oxidative stress via increasing the antioxidant enzyme levels and reducing oxidant enzyme levels. Treatment with NAC at 2 mM increased cell viability from 43.68% ± 5.14%-66.69% ± 14.43% and decreased the apoptosis rate from 7.89% ± 0.53%-5.17% ± 0.11% in skeletal muscle cells. Additionally, NAC promoted the proliferation and differentiation of HS-induced skeletal muscle cells by upregulating the expression of PAX7, MYF5, MRF4 and MYHC. These findings suggest that NAC alleviates HS-induced oxidative damage in skeletal muscle cells and support muscle development.

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In recent years, the increase in environmental pollutants has been one of the most important factors threatening human and environmental health. Arsenic, a naturally occurring element found in soil, water, and air, easily enters the human body and leads to many metabolic disorders. In this study, we focused on the possible protective effects of N-acetylcysteine (NAC) against sodium arsenite (As)-induced toxic effects on embryonic fibroblast cells. The effects of As and NAC treatment on cells were evaluated, including cytotoxicity, oxidative stress, and apoptosis. Embryonic fibroblast cells were exposed to As (ranging from 0.01 µM to 10 µM) and NAC (at a concentration of 2 mM) for 24 h. The assessment of cytotoxicity markers, such as cell viability and lactate dehydrogenase (LDH), showed that As significantly reduced cell viability and increased LDH levels. Furthermore, we observed that As increased the amount of reactive oxygen species (ROS) in the cell, decreased the activity of antioxidant enzymes, and triggered apoptosis in cells. Additionally, our research revealed that the administration of NAC mitigates the detrimental effects of As. The results showed that As exerted hazardous effects on embryonic fibroblast cells through the induction of oxidative stress and apoptosis. In this context, our study provides evidence that NAC may have a protective effect against the toxicity of As in embryonic fibroblast cells.

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Background: As the prevalence of coronary artery disease rises, the demand for coronary artery bypass grafting (CABG) increases. A common complication after CABG is postoperative atrial fibrillation (POAF), which is linked to adverse clinical outcomes. N-acetylcysteine (NAC), an antioxidant, may mitigate oxidative stress and reduce the incidence of POAF. This meta-analysis aims to investigate the efficacy of NAC in preventing POAF after CABG. Methods: The meta-analysis was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We systematically searched multiple databases, including PubMed, Cochrane Library, ProQuest, and ScienceDirect, to identify relevant randomized controlled trials (RCTs). The intervention groups received perioperative NAC therapy, while the control groups received a placebo. The outcomes assessed were POAF incidence, all-cause mortality, and hospital length of stay (LOS). Review Manager 5.3 was used to conduct the meta-analysis. Results: Eleven RCTs involving 648 patients were included. The NAC group comprised 326 patients, while the control group comprised 322 patients. In the pooled analysis, patients in the NAC group had a significantly lower incidence of POAF (odds ratios (OR) = 0.57; 95% confidence intervals (CI) = 0.33 to 0.97; p = 0.04) and a shorter hospital LOS (weighted mean differences (WMD) = -0.66; 95% CI = -1.22 to -0.10; p = 0.02) compared to the control group. However, there was no significant difference in all-cause mortality. Conclusions: The perioperative administration of NAC can effectively reduce the incidence of POAF and hospital LOS in CABG patients. However, larger RCTs are needed to confirm these findings.

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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.

Nonopioid mediations are important to help pain control after surgery and may decrease risks of opioids. N-acetylcysteine (NAC), the treatment of acetaminophen overdose, decreased inflammation and has other positive effects on the body that may help pain after surgery. Thus, NAC has been studied to prevent abnormal heart rhythms with heart surgery, help kidneys after surgery, improve the liver after liver transplant or other live surgeries and improve breathing after anesthesia. NAC may also decrease pain and the amount of pain medications needed after surgery. While NAC is generally well tolerated and considered safe, stomach upset can occur as can itching or asthma like reactions in certain patients. This review describes how NAC may improve pain, summarizes the other ways NAC may help a patient undergoing surgery, and describes potential side effects when NAC is given.

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Background: Chronic obstructive pulmonary disease (COPD) is a common respiratory disease with acute exacerbation (AECOPD) being a common sequalae which negatively impact health status, rates of hospitalization and readmission, and disease progression. N-acetylcysteine (NAC) has been studied in COPD in both stable state and acute exacerbations, which has been shown to have small beneficial effects in stable COPD, as well as AECOPD. Yet, there has been lack of study with well-designed protocol to assess the role of NAC in more objective outcomes in AECOPD. Methods: This is a double-blind randomized controlled trial. Patients will be randomized in 1:1 ratio to receive oral NAC at 600 mg twice daily or placebo twice daily with standard of care. Partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaCO2) and the ratio of partial pressure arterial oxygen and fraction of inspired oxygen (PaO2/FiO2) will be measured on days 1 and 7. The following will be measure at baseline and on day 4 and 7: Forced expiratory volume in one second (FEV1), 24-hour sputum volume, oxygen saturation (SaO2), end-tidal CO2, Leicester Cough Questionnaire (LCQ) score, COPD Assessment Test (CAT) score, grading of wheeze and grade of dyspnoea; blood inflammatory markers (leucocyte count, neutrophil count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and high sensitivity CRP (hs-CRP)). Patients will be randomized to oral NAC at 600 mg twice daily or placebo for 7 days. The main outcome measures include: The difference in PaO2 on day 7. Secondary outcome: Change in following parameters on day 4/7 from baseline: FEV1, sputum volume, CAT score, LCQ score, SaO2, grade of wheeze; mMRC Dyspnoea Scale, end-tidal CO2, blood inflammatory marker, change in PaO2/FiO2 ratio from baseline to day 7, PaCO2 on day 7, 28 and 90 days' mortality, time to wean off supplemental oxygen, length of stay.Primary and secondary outcomes will be compared among the two treatment groups with two-sample t-test. Discussion: We hypothesize that NAC use in COPD exacerbation can provide benefits in clinical and laboratory parameters. Trial Registration: Name of the registry : ClinicalTrials.gov Trial registration number : NCT05706402. URL of the trial registry record for this trial : https://classic.clinicaltrials.gov/ct2/show/NCT05706402 Date of registration : Registered on 11th January 2023 Funding of the trial : The Health and Medical Research Fund (HMRF). Name and contact information for the trial sponsor : Wang Chung Kwok, Clinical Assistant Professor, Honorary Associate Consultant, Queen Mary Hospital, The University of Hong Kong, Hong Kong. Role of sponsor : The funder is not involved in the planning of the study, gathering, analysing, and interpreting the data, or in preparing the manuscript.

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Background: The anti-inflammatory effects of budesonide (BUN) and N-acetylcysteine (NAC) attenuate acute lung injury (ALI). The aim of this study was to investigate the effects of combination therapy consisting of BUN and NAC on ALI and the underlying mechanisms. Methods: In vitro and in vivo models of ALI were generated by LPS induction. Western blotting was used to detect the expression levels of pyroptosis-related proteins and inflammation-related factors, and RT-qPCR was used to detect the expression of miR-381. Cell proliferation and apoptosis were detected by CCK-8 and flow cytometry, respectively. ELISA was used to detect the levels of inflammation-related factors. HE staining was used to detect lung injury. Results: The results showed that LPS effectively induced pyroptosis in cells and promoted the expression of pyroptosis-related proteins (Caspase1, Gasdermin D and NLRP3) and inflammatory cytokines (TNF-α, IL-6 and IL-1ß). The combination of BUN and NAC significantly alleviated LPS-induced pyroptosis and inflammation. In addition, the combination of BUN and NAC effectively promoted miR-381 expression. Transfection of miR-381 mimics effectively alleviated LPS-induced pyroptosis and inflammation, while transfection of miR-381 inhibitors had the opposite effect. miR-381 negatively regulates NLRP3 expression. Treatment with a miR-381 inhibitor or pc-NLRP3 reversed the effects of the combination of BUN and NAC. In a mouse model of ALI, the combination of BUN and NAC effectively improved lung injury, while treatment with a miR-381 inhibitor or pc-NLRP3 effectively reversed this effect. Conclusion: Overall, this study revealed that BUN + NAC inhibits the activation of NLRP3 by regulating miR-381, thereby alleviating ALI caused by pyroptosis-mediated inflammation.

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Nasal irrigation is crucial following endoscopic sinus surgery (ESS), especially for managing chronic rhinosinusitis (CRS). This study assessed the effectiveness of N-acetylcysteine (NAC) irrigation during the post-ESS period of patients with CRS without nasal polyposis. In this prospective, single-blind randomized controlled trial, 49 patients (NAC, n = 24; saline, n = 25) undergoing ESS were assigned to receive either NAC or saline irrigations twice daily for a month. The preoperative and postoperative assessments conducted included Lund-Macka (LM) and Lund-Kennedy (LK) endoscopic scores, the Nasal Obstruction Symptom Evaluation (NOSE) scale, and the Sino-Nasal Outcome Test-20 (SNOT-20). At 2 weeks, 1 month, and 3 months after the operation, endoscopic findings and symptoms were evaluated. Both groups showed no differences in age, sex, LM and LK scores, NOSE scale, and SNOT-20 preoperatively. In terms of the endoscopic findings regarding the sinonasal mucosa after ESS, the NAC group had slightly lower scores 2 weeks, 1 month, and 3 months after the operation, but this difference was not statistically significant. The NAC group showed significant improvement in VAS scores, namely, postnasal drip (1.0, p = 0.041), smell dysfunction (0.8, p = 0.003), and crust (1.5, p = 0.034), compared to the control group's scores of 2.6, 4.7, and 3.6, respectively, 2 weeks after the operation, although no significant differences were observed in VAS scores for any symptoms 1 and 3 months after the operation. NAC was well tolerated, and no adverse events were reported. NAC irrigation showed benefits over saline irrigation in terms of improving postnasal drip, smell dysfunction, and crust after ESS for CRS without nasal polyposis in the immediate postoperative period.

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Rifaximin is FDA-approved for treatment of irritable bowel syndrome with diarrhea (IBS-D), but poor solubility may limit its efficacy against microbes in the mucus layer, e.g. Escherichia coli. Here we evaluate adding the mucolytic N-acetylcysteine (NAC) to improve rifaximin efficacy. In a resazurin checkerboard assay, combining rifaximin with NAC had significant synergistic effects in reducing E. coli levels. The optimal rifaximin + NAC combination was then tested in a validated rat model of IBS-D (induced by cytolethal distending toxin [CdtB] inoculation). Rats were inoculated with vehicle and treated with placebo (Control-PBS) or rifaximin + NAC (Control-Rif + NAC, safety), or inoculated with CdtB and treated with placebo (CdtB-PBS), rifaximin (CdtB-Rifaximin), or rifaximin + NAC (CdtB-Rif + NAC) for 10 days. CdtB-inoculated rats (CdtB-PBS) developed wide variability in stool consistency (P = 0.0014) vs. controls (Control-PBS). Stool variability normalized in rats treated with rifaximin + NAC (CdtB-Rif + NAC) but not rifaximin alone (CdtB-Rifaximin). Small bowel bacterial levels were elevated in CdtB-PBS rats but normalized in CdtB-Rif + NAC but not CdtB-Rifaximin rats. E. coli and Desulfovibrio spp levels (each associated with different IBS-D microtypes) were also elevated in CdtB-inoculated (CdtB-PBS) but normalized in CdtB-Rif + NAC rats. Cytokine levels normalized only in CdtB-Rif + NAC rats, in a manner predicted to be associated with reduced diarrhea driven by reduced E. coli. These findings suggest that combining rifaximin with NAC may improve the percentage of IBS-D patients responding to treatment.

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