The role of reactive oxygen species and oxidative stress in carbon monoxide toxicity: an in-depth analysis

Evaluation of the Neuroprotective Effects of Idebenone in an Experimental Carbon Monoxide Poisoning Model

Carbon monoxide (CO) poisoning is among the main causes of poisoning-related mortality and morbidity, primarily affecting the central nervous system and leading to delayed neurological sequelae. Idebenone exerts antioxidant and neuroprotective effects. In this study, we aimed to evaluate the specific neuroprotective effects of idebenone against CO poisoning. Forty female Wistar Albino rats were used in this study. Except the controls, the other rats inhaled 5000 ppm CO until a change in consciousness was observed. Rats with carboxyhemoglobin concentrations over 20% in blood samples collected from the tail vein were considered successful acute CO poisoning models. The rats were divided into five groups: healthy control (HC; group 1), CO + saline (CO-S; group 2), CO + 100 mg/kg idebenone (CO-I100; group 3), CO + 200 mg/kg idebenone (CO-I200; group 4), and CO + 300 mg/kg idebenone (CO-I300; group 5). Pre-determined doses of idebenon were orally administered to the rats at 24-h intervals for 5 days. The rats were anesthetized and sacrificed 24 h after the last drug dose. Histopathological and biochemical parameters were examined in the blood and hippocampus samples of the rats. Histopathological grading of neurons in the hippocampus revealed that the CO-S group exhibited the highest number of grade 1, 2, and 3 degenerative cells (all p = 0.001). Apoptotic index was the highest in the CO-S group and significantly low in the idebenone-treated groups (p = 0.001). Neuron-specific enolase and malondialdehyde levels and oxidative stress index were significantly lower in both the hippocampus and serum samples of the idebenone-treated groups than in those of the CO-S group (all p values = 0.001). Overall, idebenone inhibited degeneration due to CO-induced brain damage and exerted neuroprotective effects against oxidative stress in rats.

Predictors of delayed encephalopathy after acute carbon monoxide poisoning: a literature review

Delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) is one of the severe complications that can occur after acute carbon monoxide poisoning (ACOP). The pathogenesis of DEACMP is complex, featuring a delitescence onset and poor prognosis. As a result, many scholars are concentrating on identifying predictors of DEACMP and evaluating their effects, including clinical characteristics, laboratory indicators, neuroelectrophysiology, imaging examination, and genetic susceptibility. However, current identified predictors lack consensus and their clinical application is limited. Therefore, we need to explore new predictors. Exosomes, the smallest extracellular vesicles (EVs) with nano-size, participate in both the physiological and pathological processes of the brain, and the changes in their content can provide valuable information for clinical diagnosis and evaluation of neurodegenerative diseases, suggesting that they may serve as a potential biomarker. However, the practicability of exosomes as biomarkers of DEACMP remains unclear. In the present review, we first introduced the pathogenesis of DEACMP and the currently identified predictors. Then, we also discussed the possibility of exosomes as the biomarkers of DEACMP, aiming to stimulate more attention and discussion on this topic, thereby providing meaningful insights for future research.

Grey matter morphometry in young adult e-cigarette users, tobacco cigarette users & non-using controls

Despite the rise in electronic cigarette use in recent years, the neurobiological effects of daily e-cigarette use versus smoking cigarettes in young adults remains unknown. This study aimed to investigate the impact of regular, exclusive e-cigarette use on grey matter morphometry in young adults, age 18-25. Structural MRI data were collected from 3 distinct groups of participants (n = 78): daily, exclusive e-cigarette users; tobacco cigarette users; and non-using controls, to assess grey matter volume (GMV) differences. Voxel-based morphometry revealed significant GMV reductions in tobacco cigarette users in the left fusiform gyrus (FG), left and right inferior temporal gyrus (IFG), right middle temporal gyri, and right middle cingulate gyrus (MCG), compared to controls, as well as the anterior cingulate cortex (ACC), compared to both e-cigarette users and controls, even after adjusting for nicotine exposure history. Partial correlation analyses revealed that in tobacco cigarette users, GMV in the FG, ITG, MTG, and MCG displayed a strong, negative association with exposure history but not with nicotine dependence. GMV of the ACC was not associated with duration of use or nicotine dependence score, suggesting distinct relationships between ACC volume and smoking status and FG/ITG/MTG/MCG volume and smoking status. This indicates a distinct difference between regular tobacco cigarette and e-cigarette use, perhaps a relatively safer profile of e-cigarette use on GMV. These findings suggest that factors beyond nicotine, such as other toxicants in tobacco cigarette smoke, may contribute to the observed brain atrophy, or imply potential pre-existing vulnerabilities that might predispose individuals to take up smoking.

NOX4 Suppresses Ferroptosis Through Regulation of the Pentose Phosphate Pathway in Colorectal Cancer

OBJECTIVE

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are known as major sources of reactive oxygen species (ROS), yet their role in regulating cellular antioxidative metabolism and ferroptosis is unclear. This study assessed the expression and clinical relevance of NOXs across pan-cancer and investigated the role of NOX4 in colorectal cancer progression METHODS: We analyzed transcriptomic and survival data from The Cancer Genome Atlas (TCGA) for NOXs across 22 types of solid tumors. A CRISPR library targeting NOXs was developed for potential therapeutic target screening in colorectal cancer cells (CRCs). Techniques such as CRISPR-knockout cell lines, 1,2-13C-glucose tracing, PI staining, BrdU assays, and coimmunoprecipitation were employed to elucidate the function of NOX4 in CRCs.

RESULTS

NOX4 emerged as a key therapeutic target for colorectal cancer from TCGA data. CRISPR screening highlighted its essential role in CRC survival, with functional experiments confirming that NOX4 upregulation promotes cell survival and proliferation. The interaction of NOX4 with glucose‑6‑phosphate dehydrogenase (G6PD) was found to enhance the pentose phosphate pathway (PPP), facilitating ROS clearance and protecting CRCs against ferroptosis.

CONCLUSIONS

This study identified NOX4 as a novel ferroptosis suppressor and a therapeutic target for the treatment of colorectal cancer. The findings suggest that a coupling between NADPH oxidase enzyme NOX4 and the PPP regulates ferroptosis and reveal an accompanying metabolic vulnerability for therapeutic targeting in colorectal cancer.

Carbon Monoxide Poisoning: Diagnosis, Prognostic Factors, Treatment Strategies, and Future Perspectives

Carbon monoxide (CO) poisoning is a significant public health issue, with diagnosis often complicated by non-specific symptoms and limited access to specialised tools. Early detection is vital for preventing long-term complications. The review examines diagnostic challenges, prognostic factors, management strategies, and future advancements in CO poisoning. It highlights the limitations of current diagnostic techniques such as blood carboxyhaemoglobin levels and pulse CO-oximetry, while exploring emerging methods for rapid detection. Prognosis is influenced by exposure severity and delayed treatment, which increases the risk of neurological damage. Hyperbaric oxygen therapy (HBOT) remains the primary treatment but is not always accessible. Advances in portable CO-oximeters and biomarkers offer potential for improved early diagnosis and monitoring. Addressing resource limitations and refining treatment protocols are crucial for better patient outcomes. Future research should focus on personalised management strategies and the integration of modern technologies to enhance care.

Carbon Monoxide: A Pleiotropic Redox Regulator of Life and Death

Despite recent technological progress, carbon monoxide poisoning is still one of the leading causes of domestic and industrial morbidity and mortality. The brain is particularly vulnerable to CO toxicity, and thus the majority of survivors develop delayed movement and cognitive complications. CO binds to haemoglobin in erythrocytes, preventing oxygen delivery to tissues, and additionally inhibits mitochondrial respiration. This renders the effect of CO to be closely related to hypoxia reperfusion injury. Oxygen deprivation, as well as CO poisoning and re-oxygenation, are shown to be able to activate the production of reactive oxygen species and to induce oxidative stress. Here, we review the role of reactive oxygen species production and oxidative stress in the mechanism of neuronal cell death induced by carbon monoxide and re-oxygenation. We discuss possible protective mechanisms used by brain cells with a specific focus on the inhibition of CO-induced ROS production and oxidative stress.

Water-pipe Tobacco Components and their Association with Oxidative Stress

Oxidative stress (OS) results from an imbalance between the formation and detoxification of reactive species. Although reactive species at low or moderate levels play numerous physiological roles, high concentrations can lead to disturbances in signaling and metabolic pathways and cause different metabolic, chronic, and age-related disorders. Several endogenous and exogenous processes may lead to the formation of reactive species. The severity of OS can be reduced with the help of antioxidants. Tobacco is one of the most important environmental factors contributing to reactive species production. After cigarette smoking, water-pipe tobacco (WPT) smoking is ranked as the second most popular tobacco product. Its popularity is proliferating due to flavored products, social acceptability, etc. However, studies have shown that WPT smoking is associated with an increased risk of arterial stiffness, ischemic heart disease, and several cancer types. In this study, we aimed to review the most recent evidence on WPT smoking constituents and their association with OS.

Curcumin as a Potential Therapeutic Agent for Mitigating Carbon Monoxide Poisoning: Evidence from an Experimental Rat Study

BACKGROUND Carbon monoxide (CO) is a poisonous gas and causes tissue damage through oxidative stress. We aimed to investigate the protective value of curcumin in CO poisoning. MATERIAL AND METHODS Twenty-four female Spraque Dawley rats were divided into 4 subgroups: controls (n=6), curcumin group (n=6), CO group (n=6), and curcumin+CO group (n=6). The experimental group was exposed to 3 L/min of CO gas at 3000 ppm. Curcumin was administered intraperitoneally at a dosage of 50 mg/kg. Hippocampal tissues were removed and separated for biochemical and immunohistochemical analysis. Tissue malondialdehyde (MDA) levels, nitric oxide (NO) levels, and superoxide dismutase (SOD) and catalase (CAT) activities were assayed spectrophotometrically, and serum asymmetric dimethylarginine (ADMA) were measured using the ELISA technique. Tissue Bcl-2 levels were detected by the immunohistochemistry method. RESULTS Tissue CAT and SOD activities and NO levels were significantly lower, and MDA and serum ADMA levels were higher in the CO group than in the control group (P<0.001). The curcumin+CO group had higher CAT activities (P=0.007) and lower MDA than the CO group (P<0.001) and higher ADMA levels than the control group (P=0.023). However, there was no significant difference observed for tissue SOD activity or NO levels between these 2 groups. In the curcumin+CO group, the Bcl-2 level was higher than that in the CO group (P=0.017). CONCLUSIONS The positive effect of curcumin on CAT activities, together with suppression of MDA levels, has shown that curcumin may have a protective effect against CO poisoning.

Effects of Reactive Oxygen and Nitrogen Species on Male Fertility

Significance: In recent decades, male fertility has been severely reduced worldwide. The causes underlying this decline are multifactorial, and include, among others, genetic alterations, changes in the microbiome, and the impact of environmental pollutants. Such factors can dysregulate the physiological levels of reactive species of oxygen (ROS) and nitrogen (RNS) in the patient, generating oxidative and nitrosative stress that impairs fertility. Recent Advances: Recent studies have delved into other factors involved in the dysregulation of ROS and RNS levels, such as diet, obesity, persistent infections, environmental pollutants, and gut microbiota, thus leading to new strategies to solve male fertility problems, such as consuming prebiotics to regulate gut flora or treating psychological conditions. Critical Issues: The pathways where ROS or RNS may be involved as modulators are still under investigation. Moreover, the extent to which treatments can rescue male infertility as well as whether they may have side effects remains, in most cases, to be elucidated. For example, it is known that prescription of antioxidants to treat nitrosative stress can alter sperm chromatin condensation, which makes DNA more exposed to ROS and RNS, and may thus affect fertilization and early embryo development. Future Directions: The involvement of extracellular vesicles, which might play a crucial role in cell communication during spermatogenesis and epididymal maturation, and the relevance of other factors such as sperm epigenetic signatures should be envisaged in the future.

Red blood cell distribution width (RDW) reflects disease severity in patients with carbon monoxide poisoning: systematic literature review and meta-analysis

No definitive prognostic biomarkers for carbon monoxide (CO) poisoning have been proposed. The aim of this study is to investigate, through a systematic literature review and pooled analysis, whether red blood cell distribution width (RDW) can predict disease severity in CO-poisoned patients. We performed an electronic search in Scopus and PubMed using the keywords: 'red blood cell distribution width' OR 'RDW' AND 'carbon monoxide' AND 'poisoning,' with no time or language restrictions (i.e. through August 2023) to find clinical studies that examined the value of RDW in patients with varying severity of CO poisoning. The analysis was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 reporting checklist. We identified 29 articles, seven of which were included in our analysis, with a total of 1979 CO-poisoned patients, 25.9% of whom were severely ill. In all but one of the studies, the RWD mean or median value was higher in CO-poisoned patients with severe disease. The weighted mean difference (WMD) of RDW was 0.36 (95% confidence interval (CI), 0.26-0.47)%. In the three articles in which the severity of illness in CO-poisoned patients was defined as cardiac injury, the WMD of the RDW was 1.26 (95%CI, 1.02-1.50)%. These results suggest that monitoring RDW in CO-poisoned patients may help to determine the severity of disease, particularly cardiac injury.

Increased Long-Term Risk of Dementia in Patients With Carbon Monoxide Poisoning: A Systematic Review and Meta-Analysis of Cohort Studies

OBJECTIVE

To assess whether carbon monoxide (CO) poisoning increases the incidence of dementia.

METHODS

We searched the Cochrane Library, PubMed, and EMBASE from inception to 14 August 2022. Two authors independently selected studies, assessed the quality of included studies, and extracted data. Any disagreement was resolved by discussion with a third author. Only cohort study with an enough follow-up period was included for systematic reviews and meta-analysis.

RESULTS

Thirty-three full texts were initially searched, but only three studies met our inclusion criteria, and they were comprised of 134,563 participants who were initially free of dementia. The follow-up period ranged from 9 to 12 years. We found that CO poisoning increased the risk of dementia incidence (adjusted hazard ratio 2.61, 95% confidence interval 1.56 to 4.36, p=0.0003). Subgroup analysis showed that the increased dementia risk was significant in males but not in females, and the highest risk was in young age group, followed by in middle age group, but not in the old one.

CONCLUSION

Overall the evidence from prospective cohort studies supported a link between CO exposure and an increased dementia risk, although all the included studies were limited to Taiwanese population.

Targeting Ferroptosis Promotes Functional Recovery by Mitigating White Matter Injury Following Acute Carbon Monoxide Poisoning

Survivors experiencing acute carbon monoxide poisoning (ACMP) tend to develop white matter injury (WMI). The mechanism of ACMP-induced WMI remains unclear. Considering the role of ferroptosis in initiating oligodendrocyte damage to deteriorate WMI, exploring therapeutic options to attenuate ferroptosis is a feasible approach to alleviating WMI. Our results indicated that ACMP induced accumulation of iron and reactive oxygen species (ROS) eventually leading to WMI and motor impairment after ACMP. Furthermore, ferrostatin-1 reduced iron and ROS deposition to alleviate ferroptosis, thereafter reducing WMI to promote the recovery of motor function. The nuclear factor erythroid-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway was found to be involved in alleviating ferroptosis as seen with the administration of ferrostatin-1. The present study rationalizes that targeting ferroptosis to alleviate WMI is a feasible therapeutic strategy for managing ACMP.

Carbon Monoxide Poisoning: From Microbes to Therapeutics

Carbon monoxide (CO) poisoning leads to 50,000-100,000 emergency room visits and 1,500-2,000 deaths each year in the United States alone. Even with treatment, survivors often suffer from long-term cardiac and neurocognitive deficits, highlighting a clear unmet medical need for novel therapeutic strategies that reduce morbidity and mortality associated with CO poisoning. This review examines the prevalence and impact of CO poisoning and pathophysiology in humans and highlights recent advances in therapeutic strategies that accelerate CO clearance and mitigate toxicity. We focus on recent developments of high-affinity molecules that take advantage of the uniquely strong interaction between CO and heme to selectively bind and sequester CO in preclinical models. These scavengers, which employ heme-binding scaffolds ranging from organic small molecules to hemoproteins derived from humans and potentially even microorganisms, show promise as field-deployable antidotes that may rapidly accelerate CO clearance and improve outcomes for survivors of acute CO poisoning.

Cardiovascular biomarkers: exploring troponin and BNP applications in conditions related to carbon monoxide exposure

BACKGROUND

The diagnosis and prognosis of cardiovascular disorders are greatly aided by cardiovascular biomarkers. The uses of troponin and B-type natriuretic peptide in situations involving carbon monoxide exposure are examined in this narrative review. These biomarkers are important because they help predict outcomes in cardiovascular disorders, track the effectiveness of therapy, and influence therapeutic choices.

MAIN BODY

Clinical practice makes considerable use of B-type natriuretic peptide (BNP), which has diuretic and vasodilatory effects, and troponin, a particular marker for myocardial injury. Carbon monoxide (CO) poisoning is a major worldwide health problem because CO, a "silent killer," has significant clinical consequences. Higher risk of cardiac problems, poorer clinical outcomes, and greater severity of carbon monoxide poisoning are all linked to elevated troponin and B-type natriuretic peptide levels. BNP's adaptability in diagnosing cardiac dysfunction and directing decisions for hyperbaric oxygen therapy is complemented by troponin's specificity in identifying CO-induced myocardial damage. When combined, they improve the accuracy of carbon monoxide poisoning diagnoses and offer a thorough understanding of cardiac pathophysiology.

CONCLUSIONS

To sum up, this review emphasizes the importance of troponin and B-type natriuretic peptide (BNP) as cardiac indicators during carbon monoxide exposure. While BNP predicts long-term cardiac problems, troponin is better at short-term morbidity and death prediction. When highly sensitive troponin I (hsTnI) and B-type natriuretic peptide are combined, the diagnostic accuracy of carbon monoxide poisoning patients is improved. One of the difficulties is evaluating biomarker levels since carbon monoxide poisoning symptoms are not always clear-cut. Accurate diagnosis and treatment depend on the investigation of new biomarkers and the use of standardized diagnostic criteria. The results advance the use of cardiovascular biomarkers in the intricate field of carbon monoxide exposure.

Investigation of Cerebral Mitochondrial Injury in a Porcine Survivor Model of Carbon Monoxide Poisoning

INTRODUCTION

Carbon monoxide (CO) is a colorless and odorless gas that is a leading cause of environmental poisoning in the USA with substantial mortality and morbidity. The mechanism of CO poisoning is complex and includes hypoxia, inflammation, and leukocyte sequestration in brain microvessel segments leading to increased reactive oxygen species. Another important pathway is the effects of CO on the mitochondria, specifically at cytochrome c oxidase, also known as Complex IV (CIV). One of the glaring gaps is the lack of rigorous experimental models that may recapitulate survivors of acute CO poisoning in the early phase. The primary objective of this preliminary study is to use our advanced swine platform of acute CO poisoning to develop a clinically relevant survivor model to perform behavioral assessment and MRI imaging that will allow future development of biomarkers and therapeutics.

METHODS

Four swine (10 kg) were divided into two groups: control (n = 2) and CO (n = 2). The CO group received CO at 2000 ppm for over 120 min followed by 30 min of re-oxygenation at room air for one swine and 150 min followed by 30 min of re-oxygenation for another swine. The two swine in the sham group received room air for 150 min. Cerebral microdialysis was performed to obtain semi real-time measurements of cerebral metabolic status. Following exposures, all surviving animals were observed for a 24-h period with neurobehavioral assessment and imaging. At the end of the 24-h period, fresh brain tissue (cortical and hippocampal) was immediately harvested to measure mitochondrial respiration.

RESULTS

While a preliminary ongoing study, animals in the CO group showed alterations in cerebral metabolism and cellular function in the acute exposure phase with possible sustained mitochondrial changes 24 h after the CO exposure ended.

CONCLUSIONS

This preliminary research further establishes a large animal swine model investigating survivors of CO poisoning to measure translational metrics relevant to clinical medicine that includes a basic neurobehavioral assessment and post exposure cellular measures.

Multi-Modal Synergistic 99mTc-TRODAT-1 SPECT and MRI for Evaluation of the Efficacy of Hyperbaric Oxygen Therapy in CO-Induced Delayed Parkinsonian and Non-Parkinsonian Syndromes

Background: Delayed neuropsychiatric syndrome (DNS) is characterized by motor dysfunction after acute carbon monoxide (CO) poisoning. We examined the relationship between dopamine transporter (DAT) loss using kit-based Tc-99m-TRODAT-1 (DAT single-photon emission-computed tomography (SPECT) radioligand) and globus pallidus necrosis on MRI, DAT availability before and after hyperbaric oxygen therapy (HBOT), and feasibility of Tc-99m-TRODAT-1 as an index for parkinsonian syndrome in CO poisoning. Methods: Twenty-one CO-intoxicated patients (mean ± SD age, 38.6 ± 11.4; range, 20−68 years) with DNS underwent Tc-99m-TRODAT-1 SPECT and MRI before HBOT and follow-up Tc-99m-TRODAT-1 SPECT to assess DAT recovery. Neurological examinations for Parkinsonism were performed after development of DNS. Results: Over 70% (15/21) of DNS patients showed globus pallidus necrosis on MRI. Significantly lower bilateral striatal DAT availability was associated with globus pallidus necrosis (p < 0.005). Moreover, 68.4% (13/19) of DNS subjects with Parkinsonian syndrome had lower bilateral striatal DAT availability vs. non-parkinsonian subjects pre- or post-HBOT. The SURs for both striata increased by ~11% post-HBOT in the Parkinsonian group; however, the left striatum presented a significantly higher DAT recovery rate than the right (*** p < 0.005). Conclusions: Coupled Tc-99m TRODAT-1 SPECT and MRI could assist evaluation of Parkinsonism risk and indicate DAT availability after HBOT in CO-poisoned patients with DNS.

Preliminary Research: Application of Non-Invasive Measure of Cytochrome c Oxidase Redox States and Mitochondrial Function in a Porcine Model of Carbon Monoxide Poisoning

INTRODUCTION

Carbon monoxide (CO) is a colorless and odorless gas that is a leading cause of environmental poisoning in the USA with substantial mortality and morbidity. The mechanism of CO poisoning is complex and includes hypoxia, inflammation, and leukocyte sequestration in brain microvessel segments leading to increased reactive oxygen species. Another important pathway is the effects of CO on the mitochondria, specifically at cytochrome c oxidase, also known as Complex IV (CIV). The purpose of this ongoing study is the preliminary development of a porcine model of CO poisoning for investigation of alterations in brain mitochondrial physiology.

METHODS

Four pigs (10 kg) were divided into two groups: Sham (n = 2) and CO (n = 2). Administration of a dose of CO at 2000 ppm to the CO group over 120 minutes followed by 30 minutes of re-oxygenation at room air. The control group received room air for 150 minutes. Non-invasive optical monitoring was used to measure CIV redox states. Cerebral microdialysis was performed to obtain semi real-time measurements of cerebral metabolic status. At the end of the exposure, fresh brain tissue (cortical and hippocampal) was immediately harvested to measure mitochondrial respiration. Snap frozen cortical tissue was also used for ATP concentrations and western blotting.

RESULTS

While a preliminary ongoing study, animals in the CO group showed possible early decreases in brain mitochondrial respiration, citrate synthase density, CIV redox changes measured with optics, and an increase in the lactate-to-pyruvate ratio.

CONCLUSIONS

There is a possible observable phenotype highlighting the important role of mitochondrial function in the injury of CO poisoning.

Short-term effects of ambient air pollution on daily emergency room visits for abdominal pain: a time-series study in Wuhan, China

Short-term exposure to ambient air pollution has been proven to result in respiratory, cardiovascular, and digestive diseases, leading to increased emergency room visits (ERVs). Abdominal pain complaints provide a large proportion of the ERVs, as yet few studies have focused on the correlations between ambient air pollution and abdominal pain, especially in emergency departments within China. Daily data for daily ERVs were collected in Wuhan, China (from January 1, 2016 to December 31, 2018), including air pollution concentration (SO₂, NO₂, PM_2.5, PM₁₀, CO, and O₃), and meteorological variables. We conducted a time-series study to investigate the potential correlation between six ambient air pollutants and ERVs for abdominal pain and their effects, in different genders, ages, and seasons. A total of 16,318 abdominal pain ERVs were identified during the study period. A 10-μg/m³ increase in concentration of SO₂, NO₂, PM_2.5, PM₁₀, CO, and O₃ corresponded respectively to incremental increases in abdominal pain of 4.89% (95% confidence interval [CI]: - 1.50-11.70), 1.85% (95% CI: - 0.29-4.03), 0.83% (95% CI: - 0.05-1.72), - 0.22% (95% CI: - 0.73-0.30), 0.24% (95% CI: 0.08-0.40), and 0.86% (95% CI: 0.04 - 1.69). We observed significant correlations between CO and O₃ and increases in daily abdominal pain ERVs and positive but insignificant correlations between the other pollutants and ERVs (except PM₁₀). The effects were stronger for females (especially SO₂ and O₃: 13.53% vs. - 2.46%; 1.20% vs. 0.47%, respectively) and younger people (especially CO and O_3: 0.25% vs. 0.01%; 1.36% vs. 0.15%, respectively). Males (1.38% vs. 0.87%) and elders (1.27% vs. 0.99%) were more likely to be affected by PM_2.5. The correlations with PM_2.5 were stronger in cool seasons (1.25% vs. - 0.07%) while the correlation with CO was stronger in warm seasons (0.47% vs. 0.14%). Our time-series study suggests that short-term exposure to air pollution (especially CO and O₃) was positively correlated with ERVs for abdominal pain in Wuhan, China, and that the effects varied by season, gender and age. These data can add evidence on how air pollutants affect the human body and may prompt hospitals to take specific precautions on polluted days and maintain order in emergency departments made busier due to the pollution.

Glutamate Chemical Exchange Saturation Transfer (GluCEST) Magnetic Resonance Imaging of Rat Brain With Acute Carbon Monoxide Poisoning

OBJECTIVES

To evaluate the diagnostic and prognostic values of glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging as a quantitative method for pathogenetic research and clinical application of carbon monoxide (CO) poisoning-induced encephalopathy combined with the proton magnetic resonance spectroscopy (¹H-MRS) and the related histopathological and behavioral changes.

METHODS

A total of 63 Sprague-Dawley rats were randomly divided into four groups. Group A (n = 12) was used for animal modeling verification; Group B (n = 15) was used for magnetic resonance molecular imaging, Group C (n = 15) was used for animal behavior experiments, and Group D (n = 21) was used for histopathological examination. All the above quantitative results were analyzed by statistics.

RESULTS

The peak value of carboxyhemoglobin saturation in the blood after modeling was 7.3-fold higher than before and lasted at least 2.5 h. The GluCEST values of the parietal lobe, hippocampus, and thalamus were significantly higher than the base values in CO poisoning rats (p < 0.05) and the ¹H-MRS showed significant differences in the parietal lobe and hippocampus. In the Morris water maze tests, the average latency and distance were significantly prolonged in poisoned rats (p < 0.05), and the cumulative time was shorter and negatively correlated with GluCEST.

CONCLUSION

The GluCEST imaging non-invasively reflects the changes of glutamate in the brain in vivo with higher sensitivity and spatial resolution than ¹H-MRS. Our study implies that GluCEST imaging may be used as a new imaging method for providing a pathogenetic and prognostic assessment of CO-associated encephalopathy.

Delayed Neurological Sequelae Successfully Treated with Adjuvant, Prolonged Hyperbaric Oxygen Therapy: Review and Case Report

Carbon Monoxide (CO) intoxication is still a leading cause of mortality and morbidity in many countries. Due to the problematic detection in the environment and subtle symptoms, CO intoxication usually goes unrecognized, and both normobaric and hyperbaric oxygen (HBO) treatments are frequently administered with delay. Current knowledge is mainly focused on acute intoxication, while Delayed Neurological Sequelae (DNS) are neglected, especially their treatment. This work details the cases of two patients presenting a few weeks after CO intoxication with severe neurological impairment and a characteristic diffused demyelination at the brain magnetic resonance imaging, posing the diagnosis of DNS. After prolonged treatment with hyperbaric oxygen, combined with intravenous corticosteroids and rehabilitation, the clinical and radiological features of DNS disappeared, and the patients' neurological status returned to normal. Such rare cases should reinforce a thorough clinical follow-up for CO intoxication victims and promote high-quality studies.

Carbon Monoxide (CO), Nitric Oxide, and Hydrogen Sulfide Signaling During Acute CO Poisoning

Major toxic effects of acute carbon monoxide (CO) poisoning result from increases in reactive oxygen species (ROS) and reactive nitrogen species (RNS) producing oxidative stress. The importance of altered nitric oxide (NO) signaling in evoking increases in RNS during CO poisoning has been established. Although there is extensive literature describing NO and hydrogen sulfide (H2S) signaling in different types of cells under normal conditions, how CO poisoning-evoked deregulation of additional NO signaling pathways and H2S signaling pathways could result in cell injury has not been previously considered in detail. The goal of this article was to do this. The approach was to use published data to describe signaling pathways driven by CO bonding to different ferroproteins and then to collate data that describe NO and H2S signaling pathways that could interact with CO signaling pathways and be important during CO poisoning. Arteriolar smooth muscle cells—endothelial cells located in the coronary and some cerebral circulations—were used as a model to illustrate major signaling pathways driven by CO bonding to different ferroproteins. The results were consistent with the concept that multiple deregulated and interacting NO and H2S signaling pathways can be involved in producing cell injury evoked during acute CO poisoning and that these pathways interact with CO signaling pathways.

Pediatric Carbon Monoxide Poisoning: Effects of Hyperbaric Oxygen Therapy on Thiol/Disulfide Balance

OBJECTIVES

Carbon monoxide (CO) poisoning remains the foremost cause of poisoning worldwide. This study aimed to investigate the effects of hyperbaric oxygen therapy (HBOT) and normobaric oxygen therapy (NBOT) on thiol/disulfide homeostasis in children with CO intoxication.

METHODS

Eighty-one children aged 0 to 18 years with CO intoxication were included in this cross-sectional study. No changes were made in the routine clinical evaluation and treatment practices of the patients. Thirty-two children who received HBOT and 49 children who received NBOT were compared for serum native thiol, disulfide, and total thiol levels, as well as for the changes in disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios before and after treatment.

RESULTS

Antioxidant levels, such as native thiol and total thiol, were significantly decreased in patients who received HBOT and increased in those who received NBOT (P = 0.02 and P = 0.01, respectively). There was no statistically significant difference between the 2 groups concerning the change of native thiol/total thiol ratios (P = 0.07). In addition, there was no significant difference regarding changes in disulfide, disulfide/native thiol, and disulfide/total thiol levels before and after treatment (P = 0.39, P = 0.07, and P = 0.07, respectively).

CONCLUSIONS

Although thiol-disulfide balance is maintained in patients treated with HBOT, antioxidant levels decrease significantly compared with NBOT. Despite efficiency of HBOT in CO intoxication, oxidative stress and reperfusion injury due to hyperoxygenation should be considered in the treatment of HBOT.

Risk of acute kidney injury among patients with carbon monoxide poisoning

ABSTRACT

There is a lack of evidence supporting the association between carbon monoxide (CO) poisoning and acute kidney injury (AKI). Hence, the present study aimed to evaluate the association between CO poisoning and AKI.From 2000 to 2011, we identified patients diagnosed with CO poisoning from the inpatient claims data. Patients aged below 20 years, who had a history of chronic kidney disease or end-stage renal disease before the index date and had incomplete medical information were excluded. Control patients without CO poisoning were randomly selected from all National Health Insurance beneficiaries, and the same exclusion criteria were used. The control group was frequency matched to patients with CO poisoning based on age, sex, and year of CO poisoning diagnosis. Cox proportional hazards regression analyses were conducted to assess the effects of CO poisoning on the risk of AKI. The hazard ratios and 95% confidence interval (CI) were calculated in the models.Compared with the control cohort, patients with severe CO poisoning were 3.77 times more likely to develop AKI (95% CI = 2.20-6.46), followed by those with less severe CO poisoning (adjusted hazard ratio = 2.21, 95% CI = 1.61-3.03).The findings of this nationwide study suggest an increased risk of AKI in patients with CO poisoning.

Neuroprotective effect of targeted regulatory Nrf2 gene on rats with acute brain injury induced by carbon monoxide poisoning

Oxidative stress has been considered as an important cause of neurocyte damage induced by carbon monoxide (CO) poisoning; however, the precise mechanisms are not fully understood. The study aimed to elucidate the molecular mechanism and the neuroprotective effect of targeted regulatory nuclear factor erythroid2-related factor 2 (Nrf2) gene on acute brain injury in CO poisoning rats. An acute CO poisoning rat model was established by CO inhalation in hyperbaric oxygen chamber and followed by the administration of Nrf2 gene-loaded lentivirus. Mitochondrial membrane potential (ΔΨM), the levels of Nrf2, glutamate-cysteine ligase catalytic subunit (GCLC), catalase (CAT) and glutathione peroxidase (GSH-Px), and cell apoptosis were determined in brain tissue in rats. We found that CO poisoning could decrease ΔΨm of cells, slightly increase the expressions of Nrf2 and GCLC at mRNA and protein levels, reduce CAT and GSH-Px, and thus initiate apoptosis process. The Nrf2 gene treatment could obviously enhance the expressions of Nrf2 at mRNA and protein levels, and increase the concentrations of CAT and GSH-Px, maintain the ΔΨm of cells in brain tissue, significantly inhibit cell apoptosis as compared with the CO poisoning group (p < .05). These findings suggest that CO poisoning could induce oxidative stress and impair mitochondrial function of cells in brain tissue. The administration of Nrf2 gene could notably strengthen the antioxidant capacity of cells through regulating the downstream genes of Nrf2/antioxidant responsive element signal pathway, and positively protect cells against brain injury induced by acute severe CO poisoning.

Alterations in cerebral and cardiac mitochondrial function in a porcine model of acute carbon monoxide poisoning

OBJECTIVES

The purpose of this study is the development of a porcine model of carbon monoxide (CO) poisoning to investigate alterations in brain and heart mitochondrial function.

DESIGN

Two group large animal model of CO poisoning.

SETTING

Laboratory.

SUBJECTS

Ten swine were divided into two groups: Control (n = 4) and CO (n = 6).

INTERVENTIONS

Administration of a low dose of CO at 200 ppm to the CO group over 90 min followed by 30 min of re-oxygenation at room air. The Control group received room air for 120 min.

MEASUREMENTS

Non-invasive optical monitoring was used to measure cerebral blood flow and oxygenation. Cerebral microdialysis was performed to obtain semi real time measurements of cerebral metabolic status. At the end of the exposure, both fresh brain (cortical and hippocampal tissue) and heart (apical tissue) were immediately harvested to measure mitochondrial respiration and reactive oxygen species (ROS) generation and blood was collected to assess plasma cytokine concentrations.

MAIN RESULTS

Animals in the CO group showed significantly decreased Complex IV-linked mitochondrial respiration in hippocampal and apical heart tissue but not cortical tissue. There also was a significant increase in mitochondrial ROS generation across all measured tissue types. The CO group showed a significantly higher cerebral lactate-to-pyruvate ratio. Both IL-8 and TNFα were significantly increased in the CO group compared with the Control group obtained from plasma. While not significant there was a trend to an increase in optically measured cerebral blood flow and hemoglobin concentration in the CO group.

CONCLUSIONS

Low-dose CO poisoning is associated with early mitochondrial disruption prior to an observable phenotype highlighting the important role of mitochondrial function in the pathology of CO poisoning. This may represent an important intervenable pathway for therapy and intervention.

Simulated vehicle exhaust exposure induces sex-dependent behavioral deficits in rats

Chronic exposure to vehicle exhaust emissions are known to cause several adverse health effects. In this study, we examined the impact of several parameters of behavioral, cardiovascular and biochemical functions upon exposure of pro-oxidants CO2, NO2 and CO (simulated vehicle exhaust exposure: SVEE) in male and female rats. Adult rats were subjected to SVEE or ambient air in whole body chambers (5 h/day, 2 weeks). Male, but not female, rats developed memory deficits, and exhibited anxiety- and depression-like behavior, accompanied with significantly high levels of serum corticosterone, oxidative stress, and inflammatory markers (CRP and TNFα), associated with lower levels of total antioxidant capacity, glutathione, glyoxalase and superoxide dismutase (SOD) activities. Brain region-specific downregulation of Cu/Zn SOD, Mn SOD, GSR, PKCα, ERK1/2, CaMKIV, CREB, BDNF and NMDAR subunit protein expression were also observed in male, but not female, rats. Blood pressure, heart rate and eGFR were not negatively impacted by SVEE. Our results suggest that SVEE, through its pro-oxidant content, induces oxido-inflammation in susceptible brain regions in a sex-dependent manner.

Emerging cellular-based therapies in carbon monoxide poisoning

Carbon monoxide (CO) is an odorless and colorless gas with multiple sources that include engine exhaust, faulty furnaces, and other sources of incomplete combustion of carbon compounds such as house fires. The most serious complications for survivors of consequential CO exposure are persistent neurological sequelae occurring in up to 50% of patients. CO inhibits mitochondrial respiration by specifically binding to the heme a3 in the active site of CIV-like hydrogen sulfide, cyanide, and phosphides. Although hyperbaric oxygen remains the cornerstone for treatment, it has variable efficacy requiring new approaches to treatment. There is a paucity of cellular-based therapies in the area of CO poisoning, and there have been recent advancements that include antioxidants and a mitochondrial substrate prodrug. The succinate prodrugs derived from chemical modification of succinate are endeavored to enhance delivery of succinate to cells, increasing uptake of succinate into the mitochondria, and providing metabolic support for cells. The therapeutic intervention of succinate prodrugs is thus potentially applicable to patients with CO poisoning via metabolic support for fuel oxidation and possibly improving efficacy of HBO therapy.

Predictive Value of Gray-Matter-White-Matter Ratio on Brain Computed Tomography for Delayed Encephalopathy after Acute Carbon Monoxide Poisoning: A Retrospective Cohort Study

Background

This study is aimed at determining the predictive value of the gray-matter–white-matter ratio (GWR) on brain computed tomography for delayed encephalopathy after acute carbon monoxide (CO) poisoning (DEACMP).

Methods

This retrospective cohort study reviewed 352 patients with acute CO poisoning and who underwent the brain computed tomography test. These patients were admitted to Cangzhou Central Hospital from May 2010 to May 2020. The patients were divided into the DEACMP (n = 16) and non-DEACMP (n = 336) groups. Pearson's correlation coefficients were computed for correlation analysis. The predictive value of GWR for DEACMP was evaluated by using logistic regression analysis and receiver operator characteristic curves.

Results

The morbidity of DEACMP was 4.5% (16/352). The GWR-basal ganglia, GWR-cerebrum, and GWR-average in the DEACMP group were lower than those in the non-DEACMP group. Correlation analysis indicated that GWR-basal ganglia (r = 0.276; P < 0.001), GWR-cerebrum (r = 0.163; P = 0.002), and GWR-average (r = 0.200; P < 0.001) were correlated with DEACMP. Multivariate logistic regression analysis revealed that reduced GWR-basal ganglia, GWR-cerebrum, and GWR-average were independent risk factors (P < 0.001; P = 0.008; P = 0.001; respectively). Compared with GWR-cerebrum and GWR-average, GWR-basal ganglia had a higher area under the curve of 0.881 (95% confidence interval: 0.783–0.983) with sensitivity and specificity of 93.8% and 68.7%, respectively. The cut-off value of GWR-basal ganglia was 1.055.

Conclusion

GWR, especially GWR-basal ganglia, is an early useful predictor for DEACMP.

Neurocognitive sequelae after carbon monoxide poisoning and hyperbaric oxygen therapy

Carbon monoxide (CO) has been the leading cause of poisoning mortality in many countries and hyperbaric oxygen (HBO) is a widely accepted treatment for CO poisoning. However, some patients with CO poisoning will still develop neurocognitive sequelae regardless of HBO therapy, which can persist since CO poisoning or be present days to weeks after a recovery from CO poisoning. HBO has been used in the prevention and treatment of neurocognitive sequelae after CO poisoning, and some mechanisms are also proposed for the potential neuroprotective effects of HBO on the neurocognitive impairment after CO poisoning, but there is still controversy on the effectiveness of HBO on neurocognitive sequelae after CO poisoning. In this paper, we briefly introduce the neurocognitive sequelae after CO poisoning, summarize the potential predictive factors of neurocognitive sequelae, and discuss the use of HBO in the treatment and prevention of neurocognitive sequelae after CO poisoning.

Carbon monoxide-triggered health effects: the important role of the inflammasome and its possible crosstalk with autophagy and exosomes

Carbon monoxide (CO) has long been known as a "silent killer" because of its ability to bind hemoglobin (Hb), leading to reduced oxygen carrying capacity of Hb, which is the main cause of CO poisoning (COP) in humans. Emerging studies suggest that mitochondria is a key target of CO action that can impact key biological processes, including apoptosis, cellular proliferation, inflammation, and autophagy. Despite its toxicity at high concentrations, CO also exhibits cyto- and tissue-protective effects at low concentrations in animal models of organ injury and disease. Specifically, CO modulates the production of pro- or anti-inflammatory cytokines and mediators by regulating the NLRP3 inflammasome. Given that human diseases are strongly associated with inflammation, a deep understanding of the exact mechanism is helpful for treatment. Autophagic factors and inflammasomes interact in various situations, including inflammatory disease, and exosomes might function as the bridge between the inflammasome and autophagy activation. Thus, the interplay among autophagy, mitochondrial dysfunction, exosomes, and the inflammasome may play pivotal roles in the health effects of CO. In this review, we summarize the latest research on the beneficial and toxic effects of CO and their underlying mechanisms, focusing on the important role of the inflammasome and its possible crosstalk with autophagy and exosomes. This knowledge may lead to the development of new therapies for inflammation-related diseases and is essential for the development of new therapeutic strategies and biomarkers of COP.

COVID-19 lockdown: a boon in boosting the air quality of major Indian Metropolitan Cities

ABSTRACT

The COVID-19 lockdown has not only helped in combating the community transmission of SARS-CoV-2 but also improved air quality in a very emphatic manner in most of the countries. In India, the first phase of COVID-19 lockdown came into force on March 25, 2020, which was later continued in the next phases. The purpose of this study was to investigate the result of lockdown on air quality of major metropolitan cities-Delhi, Mumbai, Kolkata, Chennai, Bengaluru, Hyderabad, Jaipur, and Lucknow-from March 25 to May 3, 2020. For this study, the concentration of six criteria air pollutants (PM_2.5, PM₁₀, CO, NO₂, SO₂, and O₃) and air quality index during the COVID-19 lockdown period was compared with the same period of the previous year 2019. The results indicate a substantial improvement in air quality with a drastic decrease in the concentration of PM_2.5, PM₁₀, CO, and NO₂, while there is a moderate reduction in SO₂ and O₃ concentration. During the lockdown period, the maximum reduction in the concentration of PM_2.5, PM₁₀, CO, NO₂, SO₂, and O₃ was observed to be - 49% (Lucknow), - 57% (Delhi), - 75% (Mumbai), - 68% (Kolkata), - 48% (Mumbai), and - 29% (Hyderabad), respectively. The value of the air quality index (AQI) also dwindled significantly during the COVID-19 lockdown period. The maximum decline in AQI was observed - 52% in Bengaluru and Lucknow. The order of AQI was satisfactory > moderate > good > poor and the frequency order of prominent pollutants was O₃ > PM₁₀ > PM_2.5 > CO > NO₂ > SO₂ during the lockdown period in all the aforementioned metropolitan cities.

Coronary and cerebral metabolism-blood flow coupling and pulmonary alveolar ventilation-blood flow coupling may be disabled during acute carbon monoxide poisoning

Current evidence indicates that the toxicity of carbon monoxide (CO) poisoning results from increases in reactive oxygen species (ROS) generation plus tissue hypoxia resulting from decreases in capillary Po₂ evoked by effects of increases in blood [carboxyhemoglobin] on the oxyhemoglobin dissociation curve. There has not been consideration of how increases in Pco could influence metabolism-blood flow coupling, a physiological mechanism that regulates the uniformity of tissue Po₂, and alveolar ventilation-blood flow coupling, a mechanism that increases the efficiency of pulmonary O₂ uptake. Using published data, I consider hypotheses that these coupling mechanisms, triggered by O₂ and CO sensors located in arterial and arteriolar vessels in the coronary and cerebral circulations and in lung intralobar arteries, are disrupted during acute CO poisoning. These hypotheses are supported by calculations that show that the Pco in these vessels can reach levels during CO poisoning that would exert effects on signal transduction molecules involved in these coupling mechanisms.NEW & NOTEWORTHY This article introduces and supports a postulate that the tissue hypoxia component of carbon monoxide poisoning results in part from impairment of physiological adaptation mechanisms whereby tissues can match regional blood flow to O₂ uptake, and the lung can match regional blood flow to alveolar ventilation.

In vitro comparison of hydroxocobalamin (B12a) and the mitochondrial directed therapy by a succinate prodrug in a cellular model of cyanide poisoning

The objective of this study was to compare the use of hydroxocobalamin (B12a) and a succinate prodrug to evaluate for improvement in mitochondrial function in an in vitro model of cyanide poisoning. Peripheral blood mononuclear cells (PBMC) and human aortic smooth muscle cells (HASMC) incubated with 50 mM of sodium cyanide (CN) for five minutes serving as the CN group compared to controls. We investigated the following: (1) Mitochondrial respiration; (2) Superoxide and mitochondrial membrane potential with microscopy; (3) Citrate synthase protein expression. All experiments were performed with a cell concentration of 2-3 × 106 cells/ml for both PBMC and HASMC. There were four conditions: (1) Control (no exposure); (2) Cyanide (exposure only); (3) B12a (cyanide exposure followed by B12a treatment); (4) NV118 (cyanide followed by NV118 treatment). In this study the key findings include: (1) Improvement in key mitochondrial respiratory states with the succinate prodrug (NV118) but not B12a; (2) Attenuation of superoxide production with treatment of NV118 but not with B12a treatment; (3) The changes in respiration were not secondary to increased mitochondrial content as measured by citrate synthase; (4) The use of easily accessible human blood cells showed similar mitochondrial response to both cyanide and treatment to HASMC. The use of a succinate prodrug to circumvent partial CIV inhibition by cyanide with clear reversal of cellular respiration and superoxide production that was not attributed to changes in mitochondrial content not seen by the use of B12a.

Oxidative Stress and Inflammation Induced by Waterpipe Tobacco Smoking Despite Possible Protective Effects of Exercise Training: A Review of the Literature

The prevalence of waterpipe tobacco smoking (WTS), which is also known as ghalyan, shisha or hookah, is increasing rapidly around the world, especially among youth. Growing interest in this form of tobacco smoking can be traced, in part, to the use of flavored tobacco products, social acceptability as a safer option than cigarettes, and its consideration as a relaxation method or entertainment. However, there is a well-established association between WTS and oxidative stress that causes irreversible chronic pathological conditions such as cardiovascular and respiratory problems, as well as different types of cancers, and thus increases the risk of mortality. Clearly, induction of inflammation status through increased reactive oxygen species (ROS), which in turn leads to oxidative stress and harm to lipids, DNA, and proteins, is the most plausible mechanism to explain the potential harmful effects of WTS. Unlike WTS, well-designed exercise training programs increase ROS to the extent that it is beneficial to the body. In this study, we aimed to review available evidence on the impact of exercise training on oxidative stress and inflammation status. We also summarize the effect of acute and chronic WTS on different exercise capacities.

Waterpipe (shisha, hookah) smoking, oxidative stress and hidden disease potential

Due to the abundant research on the harmful effects of cigarette smoking and the strict regulations enacted by many health authorities, many smokers are seeking for safer and more acceptable tobacco forms. Waterpipe (also known as shisha or hookah) use has increased dramatically during the past decade, mostly due to its improved taste, lack of regulations and social acceptability as a safer option than cigarettes. However, recent clinical and experimental studies indicate that waterpipe use is as, or even more, harmful than cigarettes. Although they differ in the method of consumption, waterpipe tobacco has similar deleterious constituents found in cigarettes but are generated at greater amounts. These constituents are known to induce oxidative stress and inflammation, the major underlying mechanisms of a wide array of chronic pathological conditions. We review the relationship between waterpipe tobacco use and oxidative stress and the disease potential of waterpipe use.

•

Waterpipe tobacco smoking is growing in popularity globally, since it is thought to be a safer alternative to cigarette smoking.

•

The amount of harmful substances produced from one waterpipe smoking session are greater than found in a standard cigarette.

•

Waterpipe smoking can cause oxidative stress and inflammation, which precede and exacerbate multiple pathological conditions.

Evaluation of oxidative stress and antioxidant parameters in children with carbon monoxide poisoning

Objective:

In this study, we aimed to investigate oxidative stress and antioxidant parameter levels in patients with carbon monoxide (CO) poisoning.

Methods:

The study was conducted prospectively between March 1, 2015 and April 30, 2016 in the pediatric emergency department. Eligible patients included children aged 0–18 years old with a diagnosis of CO poisoning. To determination of oxidative stress and antioxidant parameter levels, venous blood with heparinized and urine samples were drawn during the admission and after normobaric oxygen (NBO) and hyperbaric oxygen (HBO) treatment.

Results:

Forty-seven children with CO poisoning for study group and 29 patients as control group were included to the study. Sixteen patients treated with HBO. Basal plasma malondialdehyde levels were found to be significantly higher in the CO poisoning group when compared with the control group ( p = 0.019). There is no significant difference in oxidative stress and antioxidant parameter levels except erythrocyte catalase enzyme levels in patients treated with NBO when comparing before and after NBO treatment ( p > 0.05). Decreasing of basal erythrocyte catalase enzyme levels were found statistically significant after NBO treatment ( p = 0.04). There was no significant difference in oxidative stress and antioxidant parameter levels in patients treated with HBO before and after therapy ( p > 0.05).

Conclusions:

CO poisoning is associated with increased lipid peroxidation in children immediately after the poisoning. However, both treatment modalities including NBO or HBO do not have a significant effect on oxidative stress or antioxidant parameter levels.

[Treatment of carbon monoxide poisoning in Germany : A retrospective single center analysis]

BACKGROUND

The symptoms of acute carbon monoxide (CO) poisoning are unspecific, ranging from headaches to unconsciousness and death. In addition to acute symptoms, delayed severe neurological sequelae may occur. While a total of 440 deaths by CO poisoning were registered in Germany in 1999, a total of 594 patients died (0.73 per 100,000 inhabitants) in 2014 and in 2015 the number even increased to 648 deaths. A national database on clinical symptoms, course of illness or quality of care concerning CO poisoning does not yet exist.

METHODS

The treatment data of patients admitted to the Hyperbaric Emergency Centre Wiesbaden (HEC) from 2013 to 2017 with CO poisoning formed the basis of the study. This was a comparative evaluation of patient demographics, poisoning sources, symptom spectrum, course of treatment and time intervals registered on the preclinical and clinical levels.

RESULTS

From 2013 to 2017 a total of 476 patients (282 men and 194 women) with an average non-invasively measured CO-Hb of 15% (Q_0.25 = 7.6%, Q_0.75 = 22.3%) were treated with hyperbaric oxygen. Heaters (n = 131), charcoal barbecues (n = 93), fires (n = 90), hookahs (n = 78) and combustion engines (n = 37) were the most frequent CO sources identified. Headaches, vertigo, nausea and syncope were the most prevalent symptoms. A median of 91 min (Q_0.25 = 53 min; Q_0.75 = 147 min) passed between first medical contact and BGA-validated diagnosis. In total, 151 patients were transferred directly to the HEC, whereas 325 patients were secondarily transferred. The delay in this subgroup took 183 min (median Q_0.25 = 138 min; Q_0.75 = 248 min). After receiving the first hyperbaric treatment, 80% were free of symptoms. Remaining symptoms included headache (10%), fatigue (8%), vertigo (5%) and nausea (3%) and 45 patients terminated further treatment. Of the patients 417 received a second hyperbaric treatment and 370 patients were treated 3 times. After the third treatment, 89% were free of symptoms and 5% still reported headaches, 3% vertigo and 2% fatigue. In total, 6 patients died and 430 patients were symptom-free after treatment.

CONCLUSION

Commonly known sources (fire, charcoal grills) aside, many poisonings by smoking a hookah were observed. This study highlights the importance of considering CO poisoning as a differential diagnosis when encountering patients, especially of younger age, with non-specific neurological symptoms, as well as the importance of early initiation of treatment. A direct correlation between CO-Hb values (whether measured noninvasively or by invasive BGA) and the initial symptoms could not be demonstrated. In total, substantial time expired between the diagnosis and start of treatment of patients transported to a primary care hospital compared to those transported directly to the HEC. Although analysis showed adequate treatment with oxygen in the preclinical interval, administration of oxygen during primary hospital stay showed room for improvement. Introducing a national CO poisoning register and uniform treatment guidelines could improve in-house clinical processes. Multicenter studies are needed to close the gaps identified in the quality of care in Germany.

Design, Synthesis, and Biological Evaluation of Allosteric Effectors That Enhance CO Release from Carboxyhemoglobin

Carbon monoxide (CO) poisoning causes between 5,000-6,000 deaths per year in the US alone. The development of small molecule allosteric effectors of CO binding to hemoglobin (Hb) represents an important step toward making effective therapies for CO poisoning. To that end, we have found that the synthetic peptide IRL 2500 enhances CO release from COHb in air, but with concomitant hemolytic activity. We describe herein the design, synthesis, and biological evaluation of analogs of IRL 2500 that enhance the release of CO from COHb without hemolysis. These novel structures show improved aqueous solubility and reduced hemolytic activity and could lead the way to the development of small molecule therapeutics for the treatment of CO poisoning.

Delayed neurologic sequelae of carbon monoxide intoxication

Altered consciousness and accompanying neurological symptoms are both complex and challenging cases for emergency physicians. These are not specific and may be a sign of a variety of medical conditions including stroke and delayed neurological sequelae (DNS) is a recurrent transient neuropsychiatric consequence of CO intoxication. DNS produces a spectrum of varying symptoms and the diagnosis is primarily made on the basis of clinical features and radiological findings from CT and conventional MRI. In clinical practice, serious CO intoxication is treated only with oxygen therapy although no effective treatment exists. Emergency physicians play a major role in managing patients presenting with CO intoxication and preventing DNS.

A novel effective chemical hemin for the treatment of acute carbon monoxide poisoning in mice

There is no effective drug for the therapy of acute carbon monoxide (CO) poisoning. The purpose of the present study was to investigate the potential preventive and therapeutic effects of hemin on an animal model of acute CO poisoning and to provide a potential therapeutic candidate drug. A total of 80 Kunming mice were randomly divided into four groups, namely the air control, acute CO poisoning, hemin-treatment + CO and hemin-pretreatment + CO groups (n=20 each). Furthermore, the mortality rate of mice, blood carboxyhaemoglobin (HbCO) concentration and serum malondialdehyde (MDA) concentration were measured, and pathological changes of the hippocampal area were determined using histochemical staining. The mice with acute CO poisoning had a 50% mortality rate at 1 h, with an increase in blood HbCO, serum MDA levels and pathological impairments of the hippocampus. Furthermore, the mortality rate, blood HbCO and serum MDA levels of mice with pretreatment and treatment of hemin were decreased. Additionally, the pathological changes of the hippocampal area were improved in the hemin-treatment and hemin-pretreatment groups compared with the mice treated with CO. These results suggest that hemin is a novel effective chemical for the prevention and treatment of acute CO poisoning in mice. Therefore, the present study provides a novel method and experimental basis for the application of hemin in treating patients with acute CO poisoning.

Effects of air pollution on human health and practical measures for prevention in Iran

Air pollution is a major concern of new civilized world, which has a serious toxicological impact on human health and the environment. It has a number of different emission sources, but motor vehicles and industrial processes contribute the major part of air pollution. According to the World Health Organization, six major air pollutants include particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. Long and short term exposure to air suspended toxicants has a different toxicological impact on human including respiratory and cardiovascular diseases, neuropsychiatric complications, the eyes irritation, skin diseases, and long-term chronic diseases such as cancer. Several reports have revealed the direct association between exposure to the poor air quality and increasing rate of morbidity and mortality mostly due to cardiovascular and respiratory diseases. Air pollution is considered as the major environmental risk factor in the incidence and progression of some diseases such as asthma, lung cancer, ventricular hypertrophy, Alzheimer's and Parkinson's diseases, psychological complications, autism, retinopathy, fetal growth, and low birth weight. In this review article, we aimed to discuss toxicology of major air pollutants, sources of emission, and their impact on human health. We have also proposed practical measures to reduce air pollution in Iran.

Neuroprotective Effects of Simvastatin and Cilostazol in L-Methionine-Induced Vascular Dementia in Rats

Vascular dementia (VaD) is a degenerative cerebrovascular disorder that leads to progressive decline in cognitive abilities and memory. Several reports demonstrated that oxidative stress and endothelial dysfunction are principal pathogenic factors in VaD. The present study was constructed to determine the possible neuroprotective effects of simvastatin in comparison with cilostazol in VaD induced by L-methionine in rats. Male Wistar rats were divided into four groups. Group I (control group), group II received L-methionine (1.7 g/kg, p.o.) for 32 days. The remaining two groups received simvastatin (50 mg/kg, p.o.) and cilostazol (100 mg/kg, p.o.), respectively, for 32 days after induction of VaD by L-methionine. Subsequently, rats were tested for cognitive performance using Morris water maze test then sacrificed for biochemical and histopathological assays. L-methionine induced VaD reflected by alterations in rats' behavior as well as the estimated neurotransmitters, acetylcholinesterase activity as well as increased brain oxidative stress and inflammation parallel to histopathological changes in brain tissue. Treatment of rats with simvastatin ameliorated L-methionine-induced behavioral, neurochemical, and histological changes in a manner comparable to cilostazol. Simvastatin may be regarded as a potential therapeutic strategy for the treatment of VaD. To the best of our knowledge, this is the first study to reveal the neuroprotective effects of simvastatin or cilostazol in L-methionine-induced VaD. Graphical Abstract ᅟ.

Disulfide stress in carbon monoxide poisoning

OBJECTIVES

Carbon monoxide (CO) remains the most common cause of lethal poisoning around the world. The purpose of this study was to investigate the homeostasis between thiol-disulfide couples and to evaluate oxidative status comprehensively in acute CO poisoning, using new parameters along with other well-known oxidant-antioxidant molecules.

DESIGN AND METHODS

This case study consisted of 43 subjects who were diagnosed with carbon monoxide poisoning and 35 healthy individuals who were used as controls. Thiol-disulfide paired tests were examined in both groups using the method developed recently.

RESULTS

Patients with CO poisoning had significantly higher levels of serum disulfide than the control patients (20.7±5.03 versus 16.43±3.97, p=0.001). Native thiol and total thiol levels were lower in the CO patient group than in the control group (p<0.001, for each variable). The disulfide/native thiol ratios and disulfide/total thiol ratios were significantly higher, while native thiol/total thiol ratios were significantly lower, in patients with acute CO poisoning than in the healthy controls (p<0.001, for all ratios). The disulfide/native ratios were negatively correlated with both total antioxidant response and paraoxonase and arylesterase values and were positively correlated with total oxidant status and ceruloplasmin values (p<0.05, for all correlations).

CONCLUSIONS

Excessive disulfide levels and their related ratios were found in CO poisoning patients. In particular, the disulfide/native thiol ratio was identified as an indicator for overall oxidative status. Among CO poisoning patients, the thiol-disulfide balance was found to be impaired. Therefore, the disruption of thiol-disulfide homeostasis might be involved in CO toxicity.

Possible role of antioxidants and nitric oxide inhibitors against carbon monoxide poisoning: Having a clear conscience because of their potential benefits

Carbon monoxide poisoning is one of the important emergency situations manifested by primarily acute and chronic anoxic central nervous system (CNS) injuries and other organ damages. Current descriptions and therapeutic approaches have been focused on the anoxic pathophysiology. However, this point of view incompletely explains some of the outcomes and needs to be investigated extensively. Considering this, we propose that reactive oxygen species (ROS) including especially nitric oxide (NO) are likely to be a key concept to understand the emergency related to CO poisoning and to discover new therapeutic modalities in CO toxicity. If we consider the hypothesis that ROS is involved greatly in acute and chronic toxic effects of CO on CNS and some other vital organs such as heart, it follows that the antioxidant and anti-NO therapies might give the clinicians more opportunities to prevent deep CNS injury. In support of this, we review the subject in essence and summarize clinical and experimental studies that support a key role of ROS in the explanation of pathophysiology of CO toxicity as well as new treatment modalities after CO poisoning.