Low Levels Of Carbon Monoxide Research Articles

Low level carbon monoxide detection using chemically reduced graphene oxide deposited ZnO nanorods

Carbon monoxide (CO) is a toxic and extremely dangerous gas commonly produced from partial combustion of fossil fuels from automobiles, industries and power plants, etc. Prolonged inhalation of CO with higher concentration (150–200 ppm) causes convulsions, respiratory arrest and even may lead to death. Therefore, a low-cost highly sensitive CO sensor with low detection limit is needed for environmental and biomedical applications. A resistive CO gas sensor was fabricated using zinc oxide nanorods (ZnO NRs). The sensor sensitivity, response, and detection limit have been enhanced by depositing reduced graphene oxide (rGO). The maximum sensitivity was obtained with 25 µl rGO loading at ∼190 °C operating temperature. The sensor demonstrated high selectivity towards the interfering gases like nitric oxide, acetone, alcohol and ammonia. rGO loaded ZnO NRs based CO gas sensor exhibited sensitivity 0.9 ppm-1 with lower limit of detection ∼14.3 ppb.

Association between risk of preterm birth and long-term and short-term exposure to ambient carbon monoxide during pregnancy in chongqing, China: a study from 2016-2020

BackgroundPreterm birth (PTB) is an important predictor of perinatal morbidity and mortality. Previous researches have reported a correlation between air pollution and an increased risk of preterm birth. However, the specific relationship between short-term and long-term exposure to carbon monoxide (CO) and preterm birth remains less explored.MethodsA population-based study was conducted among 515,498 pregnant women in Chongqing, China, to assess short-term and long-term effects of CO on preterm and very preterm births. Generalized additive models (GAM) were applied to evaluate short-term effects, and exposure-response correlation curves were plotted after adjusting for confounding factors. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using COX proportional hazard models to estimate the long-term effect.ResultsThe daily incidence of preterm and very preterm birth was 5.99% and 0.41%, respectively. A positive association between a 100 µg/m³ increase in CO and PTB was observed at lag 0–3 days and 12–21 days, with a maximum relative risk (RR) of 1.021(95%CI: 1.001–1.043). The exposure-response curves (lag 0 day) revealed a rapid increase in PTB due to CO. Regarding long-term exposure, positive associations were found between a 100 µg/m3 CO increase for each trimester(Model 2 for trimester 1: HR = 1.054, 95%CI: 1.048–1.060; Model 2 for trimester 2: HR = 1.066, 95%CI: 1.060–1.073; Model 2 for trimester 3: HR = 1.007, 95%CI: 1.001–1.013; Model 2 for entire pregnancy: HR = 1.080, 95%CI: 1.073–1.088) and higher HRs of very preterm birth. Multiplicative interactions between air pollution and CO on the risk of preterm and very preterm birth were detected (P- interaction<0.05).ConclusionsOur findings suggest that short-term exposure to low levels of CO may have protective effects against preterm birth, while long-term exposure to low concentrations of CO may reduce the risk of both preterm and very preterm birth. Moreover, our study indicated that very preterm birth is more susceptible to the influence of long-term exposure to CO during pregnancy, with acute CO exposure exhibiting a greater impact on preterm birth. It is imperative for pregnant women to minimize exposure to ambient air pollutants.

Impact of air pollution and climate change on mental health outcomes: an umbrella review of global evidence.

The impact of air pollution and climate change on mental health has recently raised strong concerns. However, a comprehensive overview analyzing the existing evidence while addressing relevant biases is lacking. This umbrella review systematically searched the PubMed/Medline, Scopus and PsycINFO databases (up to June 26, 2023) for any systematic review with meta-analysis investigating the association of air pollution or climate change with mental health outcomes. We used the R metaumbrella package to calculate and stratify the credibility of the evidence according to criteria (i.e., convincing, highly suggestive, suggestive, or weak) that address several biases, complemented by sensitivity analyses. We included 32 systematic reviews with meta-analysis that examined 284 individual studies and 237 associations of exposures to air pollution or climate change hazards and mental health outcomes. Most associations (n=195, 82.3%) involved air pollution, while the rest (n=42, 17.7%) regarded climate change hazards (mostly focusing on temperature: n=35, 14.8%). Mental health outcomes in most associations (n=185, 78.1%) involved mental disorders, followed by suicidal behavior (n=29, 12.4%), access to mental health care services (n=9, 3.7%), mental disorders-related symptomatology (n=8, 3.3%), and multiple categories together (n=6, 2.5%). Twelve associations (5.0%) achieved convincing (class I) or highly suggestive (class II) evidence. Regarding exposures to air pollution, there was convincing (class I) evidence for the association between long-term exposure to solvents and a higher incidence of dementia or cognitive impairment (odds ratio, OR=1.139), and highly suggestive (class II) evidence for the association between long-term exposure to some pollutants and higher risk for cognitive disorders (higher incidence of dementia with high vs. low levels of carbon monoxide, CO: OR=1.587; higher incidence of vascular dementia per 1 μg/m3 increase of nitrogen oxides, NOx: hazard ratio, HR=1.004). There was also highly suggestive (class II) evidence for the association between exposure to airborne particulate matter with diameter ≤10μm (PM10) during the second trimester of pregnancy and the incidence of post-partum depression (OR=1.023 per 1 μg/m3 increase); and for the association between short-term exposure to sulfur dioxide (SO2) and schizophrenia relapse (risk ratio, RR=1.005 and 1.004 per 1 μg/m3 increase, respectively 5 and 7 days after exposure). Regarding climate change hazards, there was highly suggestive (class II) evidence for the association between short-term exposure to increased temperature and suicide- or mental disorders-related mortality (RR=1.024), suicidal behavior (RR=1.012), and hospital access (i.e., hospitalization or emergency department visits) due to suicidal behavior or mental disorders (RR=1.011) or mental disorders only (RR=1.009) (RR values per 1°C increase). There was also highly suggestive (class II) evidence for the association between short-term exposure to increased apparent temperature (i.e., the temperature equivalent perceived by humans) and suicidal behavior (RR=1.01 per 1°C increase). Finally, there was highly suggestive (class II) evidence for the association between the temporal proximity of cyclone exposure and severity of symptoms of post-traumatic stress disorder (r=0.275). Although most of the above associations were small in magnitude, they extend to the entire world population, and are therefore likely to have a substantial impact. This umbrella review classifies and quantifies for the first time the global negative impacts that air pollution and climate change can exert on mental health, identifying evidence-based targets that can inform future research and population health actions.

RCCI combustion of ammonia in dual fuel engine with early injection of diesel fuel

Ammonia has gained considerable attention as a valuable, carbon-free alternative fuel for internal combustion engine (ICE) applications. The growing interest in ammonia's potential as an energy source stems primarily from its advantageous storage and transport properties. The reactivity-controlled compression ignition (RCCI) combustion mode presents a promising avenue for overcoming the challenges intrinsic to conventional diesel engines, such as elevated nitrogen oxides (NOx) and particulate matter (PM) emissions. Additionally, it addresses the limitations of both homogeneous charge compression ignition (HCCI) combustion (limited operational range) and premixed charge compression ignition (PCCI) combustion (diminished power output). The application of an ammonia-based RCCI combustion strategy emerges as a viable pathway for harnessing ammonia as a fuel. In this study, a numerical simulation on a single-cylinder heavy-duty engine operated in RCCI mode is conducted utilizing ammonia and diesel as fuels. The engine is operated at medium load and 910 RPM. The simulation results are validated against experimental data sourced from existing literature. The study investigates the impact of varying ammonia energy fractions, injection timing, and intake valve close temperature (TIVC) on key operational characteristics of the engine including in-cylinder pressure, heat release rate (HRR), combustion efficiency (CE), indicated mean effective pressure (IMEP), and emission levels. The results indicated that increasing the ammonia energy fraction within the RCCI combustion mode, transitioning from 30 % to 70 %, leads to a notable enhancement in IMEP, while maintaining low levels of carbon monoxide (CO), hydrocarbons (HC), unburned ammonia, and nitrous oxide (N2O) as greenhouse gases (GHG). Furthermore, increasing ammonia's energy fraction yielded a discernible reduction in NOx emissions and carbon dioxide (CO2). Conversely, the RCCI combustion mode attained superiority over the dual fuel combustion mode by simultaneously elevating CE and diminishing emissions of GHG, (CO2 and N2O) as well as unburned NH3.

Management of domestic hot water system based on the example of a gas-fired instantaneous water heater

Purpose: The aim of the study was to present the actual efficiency of a gas-fired instantaneous water heater for the production of domestic hot water. Design/methodology/approach: The object of the study was a gas-fired instantaneous domestic hot water heater located in a flat in Krakow. Measurements with a suitable device were carried out for three basic variants of hot water preparation, defined as showering, washing hands and washing dishes. Findings: The tests and analyses carried out have revealed that the current efficiency (average efficiency based on 3 measurements – 77.61%) differs radically from that indicated on the water heater data sheet. Such a drop in efficiency may be caused e.g. by fouling of the surface of the heat exchanger on the flue gas side and scaling of the exchanger on the heated side. Research limitations/implications: The tests proved that the heater did not reach its nominal efficiency during the tests, but on the other hand, simulations of different intensities and durations of water consumption did not drastically change the efficiency of hot water preparation. Practical implications: Regular cleaning of the exchanger would probably reduce the difference between the efficiency declared by the manufacturer and the one achieved during the tests. A clean heater will also ensure a sufficiently low level of carbon monoxide in the flue gas, which has a real impact on the safety of the appliance. Social implications: The values obtained from the measurements for each operating mode can help occupants understand how to prepare water most efficiently with this particular appliance, which will have a real impact on the bills they pay. The user will be provided with information on what percentage of energy they use from the volume of gas burned. Originality/value: Gas-fired instantaneous water heaters provide an efficient and energy-saving solution, especially in situations where the demand for hot water is low, and immediate access to it is crucial. Keywords: hot water, hot water management, gas-fired instantaneous water heater. Category of the paper: Research paper.

Experimental Investigation of Single-Cylinder Engine Performance Using Biodiesel Made from Waste Swine Oil

The global push towards sustainable energy solutions has intensified research into alternative fuels, such as biodiesel. This study investigates the performance and emission characteristics of biodiesel derived from waste swine oil in comparison to traditional diesel fuel. Using an engine running at 75% load across a range of speeds (1200 rpm to 1800 rpm), various metrics such as Brake-Specific Fuel Consumption (BSFC), Brake Thermal Efficiency (BTE), and emissions including Carbon Monoxide (CO), Hydrocarbon (HC), Carbon Dioxide (CO2), Nitrogen Oxide (NOx), and smoke opacity were measured. The biodiesel demonstrated a higher BSFC (270 g/kWh) compared to diesel (245 g/kWh) but showed reduced Brake Thermal Efficiency (28.5% vs. 29.8%) compared to diesel. In terms of emissions, biodiesel blends recorded lower levels of CO, HC, and smoke opacity, but elevated levels of CO2 and NOx. The results indicate that while biodiesel from waste swine oil presents some environmental benefits, such as reduced CO, HC, and smoke emissions, challenges remain in terms of higher NOx emissions and less efficient fuel consumption.

Association between ambient air pollutant interaction with kidney function in a large Taiwanese population study.

The associations and interactions between kidney function and other air pollutants remain poorly defined. Therefore, the aim of this study was to evaluate associations among air pollutants, including particulate matter (PM) with a diameter ≤ 2.5μm (PM2.5), PM10 (PM with a diameter ≤ 10μm), carbon monoxide (CO), nitrogen oxide (NO), nitrogen oxides (NOx), sulfur dioxide (SO2), and ozone (O3) with kidney function, and explore interactions among these air pollutants on kidney function. We used the Taiwan Air Quality Monitoring and Taiwan Biobank databases to derive data on community-dwelling individuals in Taiwan and daily air pollution levels, respectively. We enrolled 26,032 participants. Multivariable analysis showed that high levels of PM2.5, PM10, O3 (all p < 0.001), and SO2 (p = 0.001) and low levels of CO, NO (both p < 0.001), and NOx (p = 0.047) were significantly correlated with low estimated glomerular filtration rate (eGFR). With regard to negative effects, the interactions between PM2.5 and PM10 (p < 0.001), PM2.5 and PM10 (p < 0.001), PM2.5 and SO2, PM10 and O3 (both p = 0.025), PM10 and SO2 (p = 0.001), and O3 and SO2 (p < 0.001) on eGFR were significantly negatively. High PM10, PM2.5, O3, and SO2 were associated with a low eGFR, whereas high CO, NO, and NOx were associated with a high eGFR. Furthermore, negative interactions between PM2.5 and PM10, O3 and SO2, PM10 and O3, PM2.5 and SO2, and PM10 and SO2 on eGFR were observed. The findings of this study have important implications for public health and environmental policy. Specifically, the results of this study may be useful in individuals and organizations to take action to reduce air pollution and promote public health.

Investigative research of diesel/ethanol advanced combustion strategies: A comparison of Premixed Charge Compression Ignition (PCCI) and Direct Dual Fuel Stratification (DDFS)

Direct Dual Fuel Stratification (DDFS) is a new low-temperature combustion (LTC) approach that employs dual fuel direct injection in the combustion chamber. In this method, a relatively small proportion of diesel fuel was pre-injected and utilized to activate the burning of the premixed charge followed by direct injection of a diesel/ethanol mixture (75% diesel, 25% ethanol by volume) into the combustion chamber near TDC. The DDFS approach generates a lower reactivity charge in the central sector of the combustion chamber and a stronger reactivity charge along the wall. For the examination of combustion vibrations and acoustic, a new technique dependent on the fast Fourier transform (FFT) of the cylinder vibration statistics was used. Whereas the PCCI combustion technique is more likely to cause knocking than the typical diesel CI, the results show that charge stratification in DDFS combustion does have a good effect in reducing vibration intensity. Owing to the improved controllability of the start of combustion and burning period, DDFS combustion attained a brake thermal efficiency (BTE) of 51%, which was larger than CI and PCCI. DDFS shows ultra-low nitrogen oxide (NOx) (below 1 g/kW-h), mild carbon monoxide (CO) (below 6 g/kW-h), and unburned hydrocarbons (UHC) emissions. Because of the higher thermal efficiency and a decreased carbon source due to presence of ethanol, DFFS combustion could produce lower CO levels by up to 34% when compared to PCCI.

Screening patients for unintentional carbon monoxide exposure in the Emergency Department: a cross-sectional multi-centre study.

Low-level exposure to carbon monoxide (CO) is a significant health concern but is difficult to diagnose. This main study aim was to establish the prevalence of low-level CO poisoning in Emergency Department (ED) patients. A prospective cross-sectional study of patients with symptoms of CO exposure was conducted in four UK EDs between December 2018 and March 2020. Data on symptoms, a CO screening tool and carboxyhaemoglobin were collected. An investigation of participants' homes was undertaken to identify sources of CO exposure. Based on an ED assessment of 4175 participants, the prevalence of suspected CO exposure was 0.62% (95% CI; 0.41-0.91%). CO testing in homes confirmed 1 case of CO presence and 21 probable cases. Normal levels of carboxyhaemoglobin were found in 19 cases of probable exposure and in the confirmed case. This study provides evidence that ED patients with symptoms suggestive of CO poisoning but no history of CO exposure are at risk from CO poisoning. The findings suggest components of the CO screening tool may be an indicator of CO exposure over and above elevated COHb. Clinicians should have a high index of suspicion for CO exposure so that this important diagnosis is not missed.

Comparison of four low-level carbon monoxide alarms suitable for home use or when traveling

Introduction/Background: Interest in carbon monoxide (CO) alarms that are more sensitive than is required for standard residential CO alarms is growing, as reflected by increased marketing of “low-level” alarms capable of measuring CO levels as low as 10 PPM. At the same time, publicity surrounding CO poisoning events among travelers in lodging facilities has stimulated interest in travel CO alarms. We sought to evaluate four low-level alarms that could be used in the home and especially when traveling. Materials/Methods: Two each of four brands of low-level alarms (CO Experts, Forensics, Kidde, and Sensorcon) were acquired by retail purchase and tested. The eight alarms were simultaneously exposed in an environment with a slowly increasing level of CO from indoor burning of charcoal briquets. CO levels displayed on the alarms were recorded once per minute. Activation of preset alerts on the alarms were noted. Finally, alarms were compared for ease of use and features available. Results: All brands of alarms measured CO similarly over the range from 10-120 PPM. All alarms performed as claimed by their manufacturers, both regarding range of CO reported and preset alert activation. Each alerted at CO levels below that required by the Underwriters Laboratories 2034 Standard. Summary/Conclusions: Since all low-level CO alarms tested measured CO similarly, consumers seeking a low-level CO alarm for use while traveling should base their decision on features desired and price. There are definite differences between the alarms tested, in terms of features, expected durability, ease of operation and price. 10.22462/05.06.2022.4

Prediction of Carbon Monoxide (CO) Atmospheric Pollution Concentrations with Machine Learning and Time Series Analysis in Langkawi, Malaysia

Carbon monoxide (CO) is a non-irritant toxic and odourless gas produced from the incomplete combustion of fossil fuels. Long-term exposures to lower levels of carbon monoxide have wide implications for human health. Thus, an early warning system for CO atmospheric concentration with an accurate and reliable forecasting method is crucial. Studies for predicting CO atmospheric concentration are still limited in Malaysia especially using data science approaches. This study aims to develop and predict future CO concentration for the next few hours by using the statistical time series approach and machine learning approach. The data used for the project is the air quality data of the monitoring station in Langkawi, Malaysia. The data mining tool used for this project is RapidMiner Studio. Based on the results, it showed that Time Series analysis with deep learning gave a reasonably good CO concentration prediction for the next 3 hours with a relative error of approximate 10%. The model developed in this project can be used by authorities as public health’s protection measure to provide an early alarm for alerting the Malaysian populations on the air pollution issue.

Prospective Cohort Study on the Effect of an Intervention to Reduce Household Air Pollution Among Sudanese Women and Children.

Background.Exposure to household air pollution through the burning of biomass fuels is a global health concern and can lead to negative health outcomes such as asthma and lung disease.Objectives.The goal of this four-year study was to determine whether an intervention to reduce household air pollution (HAP) which included health education and a new well-ventilated cooking location would reduce exposure to HAP, lower carbon monoxide (CO) levels and improve the health of women and children in Port Sudan, Sudan.Methods.In 2016, 115 women of low socioeconomic status and their children were invited to participate in the study at two women's centers. One hundred and eleven women consented to participate and were divided into study and control groups on the basis of home ownership. Women who owned their homes learned about the adverse effects of HAP and a well-ventilated outside cooking location (rakoobah) was provided. Control women did not receive HAP education or a rakoobah. Questionnaires were used to assess the effect of education and a new well-ventilated cooking location for a group of Sudanese women who cook with biomass fuels. CO-oximetry was performed. Each year from 2017–2019, the questionnaires and CO-oximetry were repeated.Results.Sixty-five women and 33 children were assigned to the study group and 46 women and 19 children were assigned to the control group in 2016. Women were enrolled in 2016 with CO levels of 17.8% and 17.4%, respectively. One year later some of the study group women had lower CO levels and others higher, while the CO levels of the controls were stable. An intensive HAP education program was started for the study group women. By 2019, the last study year, the CO levels of both the study and control group women had dropped to normal levels of 2.9% and 3.1%, respectively. Control group women may have benefited from the HAP education and modeled behavior of those in the study group.Conclusions.The health impact of the change in cooking location was unclear, yet both groups reported fewer health care visits in 2019. Education and an outside cooking location resulted in lower CO levels of Sudanese women and children.Participant Consent.ObtainedEthics Approval.The study was approved by the Penn State Milton S. Hershey Medical Center Institutional Review Board and the Ethics Committee of the Red Sea University Faculty of Medicine located in Port Sudan, Sudan.Competing Interests.The authors declare no competing financial interests.

Screening and management of unintentional low-level carbon monoxide exposure in the emergency department.

Unintentional carbon monoxide (CO) exposure, sometimes referred to as CO poisoning, is a serious threat to health and can have long-term effects on the neurological and respiratory systems. Patients who have been exposed can present to emergency departments (ED) with non-specific signs and symptoms, which makes it challenging to diagnose. This article describes the pathophysiology, signs and symptoms, and ED management of patients with possible or confirmed low-level CO exposure. It is important for emergency nurses to recognise patients with unintentional CO exposure so that treatment is provided and measures taken to prevent further exposure.

Be alert to the silent killer of low-level carbon monoxide poisoning

Be alert to the silent killer of low-level carbon monoxide poisoning

Association between short-term exposure to sulfur dioxide and carbon monoxide and ischemic heart disease and non-accidental death in Changsha city, China.

BackgroundTo investigate the effects of short-term exposure to sulfur dioxide (SO2) and carbon monoxide (CO) in the central and southern China areas on ischemic heart disease (IHD) and non-accidental deaths.MethodWe investigated the associations between short-term exposure to SO2 and CO in a city in south-central China and IHD and non-accidental death using a time-series design and generalized additive models with up to a 5-day lag adjusting for day of the week, temperature, air pressure, wind speed, and relative humidity. The relative risks of IHD and non-accidental death per 10-unit increase in SO2 and CO were derived from zero to five days in single-pollutant models.ResultsBetween 2016 and 2018, a total of 10,507 IHD and 44,070 non-accidental deaths were identified. The largest significant relative risk for IHD death was lag 02 for both SO2 (1.080; 95% confidence interval: 1.075–1.084) and CO (5.297; 95% confidence interval: 5.177–5.418) in single-pollutants models. A significant association was shown at all lag multiple-day moving averages. Two-pollutant models identified an association between SO2 and mortality when adjusting for CO. In stratified analyses, SO2 exhibited a stronger association with death during the cold season, while CO exhibited a stronger association with mortality from IHD during the warm season. The risk of death was more robust in the elderly for both pollutants, but was greater in men for CO and in women for SO2.ConclusionsOverall, we found an association between short-term exposure to low-level SO2 and CO and the risk of IHD and non-accidental death.

First Report of Red Blood Cell Lifespan in a Marine Mammal: An Insight Into Endogenous Carbon Monoxide (CO) Production

Deep-diving marine mammals are known to have high concentrations of hemoglobin (Hb), experience hypoxemia from extended breath-holds, and ischemia-reperfusion events in tissues from the physiological dive response. However, certain deep-diving seals (e.g., elephant and Weddell seals) are known to have levels of carbon monoxide (CO) in their blood that are similar to those seen in chronic cigarette smokers (>10% carboxyhemoglobin; COHb). The source of the high CO in the seals is currently unknown. The gas is naturally produced in humans and lab animals as a byproduct of heme degradation, by heme oxygenase enzymes. Therefore, CO production is tightly correlated with red blood cell (RBC) lifespan and associated Hb degradation, as shown by higher COHb (average 1.9%, maximum 9.7%) in patients with shortened RBC lifespans due to hemolytic anemia. Although normally considered a toxic gas, low levels of CO are naturally produced in most mammals (≤ 1% COHb in healthy humans), and exposure to moderate concentrations of exogenous CO has shown to elicit cytoprotective effects (e.g., anti-inflammation) in tissues exposed to hypoxia or ischemia-reperfusion events. Therefore, there is a desire to ascertain the mechanisms behind the regulation of elevated CO in marine mammals. Similar to humans, the production of high concentrations of CO in marine mammals is hypothesized to be directly related to their RBC lifespan. The RBC lifespan has been determined in a variety of terrestrial vertebrates, but never reported for any marine mammal species. In terrestrial mammals, there is an allometric relationship with larger animals having longer RBC lifespans (RBC lifespan (days) = (body mass (kg)0.132) (68) + 49). This study reports the first measurements of RBC lifespan in a marine mammal, the shallow-diving bottlenose dolphin (mass = 216 ± 23 kg, Hb = 14 g/dl). We hypothesize that the bottlenose dolphin would have a RBC lifespan that is similar to healthy humans (~120 days). Our results show the RBC lifespan of the bottlenose dolphin is 165.7 ± 18.4 days. Like humans, bottlenose dolphins also had low levels of CO in their blood (1.6 ± 0.5 % COHb) and exhaled breath (2.4 ± 1.0 ppm). Ongoing measurements in larger, deeper-diving mammals (e.g., beluga whales, 747 ± 244 kg, Hb = 21 g/dl), will further reveal the impact of heme stores and body mass on RBC lifespan and endogenous CO production in mammals.

Deterministic and Stochastic Cellular Mechanisms Contributing to Carbon Monoxide Induced Ventricular Arrhythmias.

Chronic exposure to low levels of Carbon Monoxide is associated with an increased risk of cardiac arrhythmia. Microelectrode recordings from rat and guinea pig single isolated ventricular myocytes exposed to CO releasing molecule CORM-2 and excited at 0.2/s show repolarisation changes that develop over hundreds of seconds: action potential prolongation by delayed repolarisation, EADs, multiple EADs and oscillations around the plateau, leading to irreversible repolarisation failure. The measured direct effects of CO on currents in these cells, and ion channels expressed in mammalian systems showed an increase in prolonged late Na+, and a decrease in the maximal T- and L-type Ca++. peak and late Na+, ultra-rapid delayed, delayed rectifier, and the inward rectifier K+ currents. Incorporation of these CO induced changes in maximal currents in ventricular cell models; (Gattoni et al., J. Physiol., 2016, 594, 4193–4224) (rat) and (Luo and Rudy, Circ. Res., 1994, 74, 1071–1096) (guinea-pig) and human endo-, mid-myo- and epi-cardial (O’Hara et al., PLoS Comput. Biol., 2011, 7, e1002061) models, by changes in maximal ionic conductance reproduces these repolarisation abnormalities. Simulations of cell populations with Gaussian distributions of maximal conductance parameters predict a CO induced increase in APD and its variability. Incorporation of these predicted CO induced conductance changes in human ventricular cell electrophysiology into ventricular tissue and wall models give changes in indices for the probability of the initiation of re-entrant arrhythmia.

Isoflurane and low-level carbon monoxide exposures increase expression of pro-survival miRNA in neonatal mouse heart.

Anesthetics such as isoflurane are known to cause apoptosis in the developing mammalian brain. However, isoflurane may have protective effects on the heart via relieving ischemia and downregulating genes related to apoptosis. Ischemic preconditioning, e.g. through the use of low levels of carbon monoxide (CO), has promise in preventing ischemia-reperfusion injury and cell death. However, it is still unclear how it either triggers the stress response in neonatal hearts. For this reason, thirty-three microRNAs (miRNAs) known to be differentially expressed following anesthesia and/or ischemic or hypoxic heart damage were investigated in the hearts from neonatal mice exposed to isoflurane or low level of CO, using an air-exposed control group. Only miR-93-5p increased with isoflurane exposure, which may be associated with the suppression of cell death, autophagy, and inflammation. By contrast, twelve miRNAs were differentially expressed in the heart following CO treatment. Many miRNAs previously shown to be responsible for suppressing cell death, autophagy, and myocardial hypertrophy were upregulated (e.g., 125b-3p, 19-3p, and 21a-5p). Finally, some miRNAs (miR-103-3p, miR-1a-3p, miR-199a-1-5p) which have been implicated in regulating energy balance and cardiac contraction were also differentially expressed. Overall, this study demonstrated that CO-mediated miRNA regulation may promote ischemic preconditioning and cardioprotection based on the putative protective roles of the differentially expressed miRNAs explored herein and the consistency of these results with those that have shown positive effects of CO on heart viability following anesthesia and ischemia-reperfusion stress.

The Relationship between City Size and Carbon Monoxide (CO) Concentration and Their Effect on Heart Rate Variability (HRV).

Generally, larger cities are characterized by traffic congestion, which is associated with higher concentrations of pollution, including Carbon Monoxide (CO) pollution. However, this convention requires empirical support on the basis of accurate and reliable measurements. In addition, the assessment of the effect of CO on the autonomic nervous system (ANS), as measured by heart rate variability (HRV), has yielded conflicting results. A majority of the (few) studies on the topic have shown that increases in CO concentration of up to about 10 parts per million (ppm) are associated with a decrease in stress and risk to health in subjects. Beyond the hypothesis postulating city size as a determinant of increased CO concentration, the hypothesis proposing a causal link between CO concentration and HRV balance also requires empirical support. This article compares CO concentrations in a large metropolis with those in a small town, analyzing the relationship between CO and the HRV responses of young women in terms of city size. Four different types of environments were compared, taking into account mediating variables. The study participants spent 35 min in selected environments (a city center, a residential environment, a park, and a home) wearing Polar devices to measure HRV, and portable devices to measure noise thermal load and CO. The average concentrations of CO in each environment were calculated, along with the time distribution of the CO concentration, and the regression slopes between the concentrations of CO and the ANS balance, as measured by the low frequency power/high frequency power ratio (LF/HF) expressed as an HRV index. The results show that, regardless of size, the cities measured were all characterized by low levels of CO, far below the maximal accepted threshold standards, and that urban residents were exposed to these concentrations for less than half of the daytime hours. Furthermore, in contrast to the common view, larger cities do not necessarily accumulate higher concentrations of CO compared to small cities, regardless of the level of transport congestion. This study confirms the findings of the majority of the other studies on the subject, which showed a decrease in stress (as measured by HRV) as a result of an increase in CO concentrations below 7 ppm. Finally, following the assessment of the differential contribution attributed to the different environmental factors, it appears that noise, thermal load, and congestion all contribute more to a higher level of HRV balance than CO. This finding highlights the importance of a multivariable approach to the study, and a remediation of the effect of environmental factors on stress in urban environments.

Ultrasound responsive carbon monoxide releasing micelle

Carbon monoxide (CO), an endogenously produced gasotransmitter, has shown various therapeutic effects in previous studies. In this work, we developed an ultrasound responsive micelle for localized CO delivery. The micelle is composed of a pluronic shell and a core of a CO releasing molecule, CORM-2. The mechanism is based on the ultrasound response of pluronics, and the reaction between CORM-2 and certain biomolecules, e.g. cysteine. The latter allows CO release without significantly breaking the micelles. In a 3.5 mM cysteine solution, the micelles released low level of CO, indicating effective encapsulation of CORM-2. Treatment with a low intensity, non-focused ultrasound led to four times as much CO as the sample without ultrasonication, which is close to that of unencapsulated CORM-2. Significantly reduced proliferation of prostate cancer cells (PC-3) was observed 24 h after the PC-3 cells were treated with the CORM-2 micelles followed by ultrasound activation.