Role of nitric oxide-derived oxidants in vascular injury from carbon monoxide in the rat.
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Studies were conducted with rats to investigate whether exposure to CO at concentrations frequently found in the environment caused nitric oxide (NO)-mediated vessel wall changes. Exposure to CO at concentrations of 50 parts per million or higher for 1 h increased the concentration of nitrotyrosine in the aorta. Immunologically reactive nitrotyrosine was localized in a discrete fashion along the endothelial lining, and this was inhibited by pretreatment with the NO synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME). The CO-induced elevations of aortic nitrotyrosine were not altered by neutropenia or thrombocytopenia, and CO caused no change in the concentration of endothelial NOS. Consequences from NO-derived stress on the vasculature included an enhanced transcapillary efflux of albumin within the first 3 h after CO exposure and leukocyte sequestration that became apparent 18 h after CO exposure. Oxidized plasma low-density lipoprotein was found immediately after CO exposure, but this was not inhibited by L-NAME pretreatment. We conclude that exposure to relatively low CO concentrations can alter vascular status by several mechanisms and that many changes are linked to NO-derived oxidants. (+info)
Carbon monoxide poisoning treated with hyperbaric oxygen: metabolic acidosis as a predictor of treatment requirements.
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A retrospective case note analysis was made of patients who received hyperbaric oxygen for carbon monoxide poisoning and were admitted to the Royal Naval Hospital Haslar between 1991 and 1995. Males predominated (38 v 10) as did cases of deliberate self poisoning (31 v 17). The most common presenting feature was unconsciousness, which is an indication for hyperbaric oxygen and therefore reflects referral patterns. If patients had not recovered completely after one hyperbaric exposure further treatments were given. The initial hydrogen ion concentration of those requiring more than one treatment was significantly higher than those who recovered after the first treatment. The initial carboxyhaemoglobin (COHb) concentration showed only a trend to being higher in the multiple treatment group. Although metabolic acidosis is well recognised, its relationship to treatment requirements has not been shown previously. Initial COHb does not always correlate well with severity of poisoning which relates to the mechanism of toxicity of carbon monoxide: binding of carbon monoxide to the intracellular oxygen carrying proteins (for example cytochromes) rather than solely to haemoglobin. These findings are consistent with this mechanism and suggests that initial acidosis is a better predictor of treatment requirements and severity than initial COHb. (+info)
British Hyperbaric Association carbon monoxide database, 1993-96.
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OBJECTIVES: To study the referral pattern of patients, poisoned with carbon monoxide and subsequently transferred to British hyperbaric oxygen facilities, from April 1993 until March 1996 inclusive. METHODS: A standard dataset was used by hyperbaric facilities within the British Hyperbaric Association. The data on each patient were sent in confidence to the Hyperbaric Unit at Whipps Cross Hospital for analysis. The epidemiology of poisoning and the population studied were analysed. Times of removal from exposure, referral to a hyperbaric facility, arrival at the hyperbaric facility, and start of treatment were recorded. Data on the outcome of the episode were documented in one of the contributing facilities. RESULTS: 575 patients exposed to carbon monoxide were reported as being referred to British hyperbaric facilities in the three years, the busiest facilities being in London and Peterborough. The proportions of accidental and non-accidental exposures were 1:1.05. Of the accidental exposures, central heating faults were responsible in 71.5% of cases (n = 206). Smoke inhalation from fires was responsible for a further 13.5% (n = 39). The mean delay to arrival in a hyperbaric oxygen facility was 9 hours and 15 minutes after removal from exposure. Recovery after treatment was sometimes incomplete. CONCLUSIONS: The reported pattern of referral was regionally weighted towards the south east of England. Smoke inhalation victims were often not referred for hyperbaric oxygen treatment. The delay to treatment was multifactorial; and the mean delay was well in excess of six hours. There is room for improvement in the consistency and speed of referral. Treatment schedules require standardisation. A central advice and referral service would be helpful. (+info)
An unusual case of carbon monoxide poisoning.
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Carbon monoxide, a gas originating from incomplete combustion of carbon-based fuels, is an important cause of human deaths. In this paper, we describe an unusual carbon monoxide poisoning in a dwelling without obvious sources of combustion gases, for which two adults had to be treated in a hyperbaric chamber. Carbon monoxide readings were taken in the house and in the neighboring homes. Methane gas and nitrogen oxide levels were also monitored in the house air. Soil samples were collected around the house and tested for hydrocarbon residues. The investigation revealed the presence of a pocket of carbon monoxide under the foundation of the house. The first readings revealed carbon monoxide levels of 500 ppm in the basement. The contamination lasted for a week. The investigation indicated that the probable source of contamination was the use of explosives at a nearby rain sewer construction site. The use of explosives in a residential area can constitute a major source of carbon monoxide for the neighboring populations. This must be investigated, and public health authorities, primary-care physicians, governmental authorities, and users and manufacturers of explosives must be made aware of this problem. (+info)
A healthy home environment?
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Over the past seven years, the U.S. Environmental Protection Agency has consistently ranked indoor air pollution among the top five risks to public health. One of the most dangerous indoor air pollutants is carbon monoxide (CO). CO can be lethal, but perhaps more important, many people suffer ill health from chronic, often undetected exposure to low levels of this gas, resulting in fatigue, headache, dizziness, nausea, and vomiting. Another dangerous pollutant is volatile organic compounds (VOCs), which come from sources including building products, cleaning agents, and paints. One VOC, formaldehyde, can act as an irritant to the conjunctiva and upper and lower respiratory tract. Formaldehyde is also known to cause nasal cancer in test animals. (+info)
Validation of the end-expired method for measuring carboxyhaemoglobin levels for the use in occupational and environmental exposure studies.
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Carbon monoxide is one of the most common toxins encountered in work settings, the gas being emitted in situations where there is incomplete combustion of carbon-containing substances. Its acute and chronic health effects have been well-documented. While identification of dangerous situations and evaluation of control measures are conducted by environmental monitoring, the body burden due to inhalation of carbon monoxide is measured by an individual's blood carboxyhaemoglobin level. Carboxyhaemoglobin level can be measured directly from a blood sample or, indirectly, by measuring the end-expired carbon monoxide level and using the charts provided to read the corresponding carboxyhaemoglobin level. As the end-expired method is not an intervention method, and is therefore easy to conduct, it is being used widely in epidemiological studies and it could also be used for individual measurements. This study presents a better statistical method for validating the end-expired method than the correlation method used and described in previous studies. (+info)
The clinical and functional measurement of cortical (in)activity in the visual brain, with special reference to the two subdivisions (V4 and V4 alpha) of the human colour centre.
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We argue below that, at least in studying the visual brain, the old and simple methods of detailed clinical assessment and perimetric measurement still yield important insights into the organization of the visual brain as a whole, as well as the organization of the individual areas within it. To demonstrate our point, we rely especially on the motion and colour systems, emphasizing in particular how clinical observations predicted an important feature of the organization of the colour centre in the human brain. With the use of data from functional magnetic resonance imaging analysed by statistical parametric mapping and independent component analysis, we show that the colour centre is composed of two subdivisions, V4 and V4 alpha the two together constituting the V4 complex of the human brain. These two subdivisions are intimately linked anatomically and act cooperatively. The new evidence about the architecture of the colour centre might help to explain why the syndrome, cerebral achromatopsia, produced by lesions in it is so variable. (+info)
Carbon monoxide poisoning associated with use of LPG-powered (propane) forklifts in industrial settings--Iowa, 1998.
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In 1998, the Iowa Department of Public Health (IDPH) and Iowa State University (ISU) Extension Department, with the assistance of local health departments, investigated a series of carbon monoxide (CO) poisonings associated with the use of liquified petroleum gas (LPG)-powered forklifts in light industry. In each episode, forklifts emitting high CO concentration levels were operated in inadequately ventilated warehouse and production facilities, which resulted in high CO accumulations. Employees at each site developed symptoms of CO poisoning, and some employees received inadequate or inappropriate medical care. This report summarizes the investigations and provides recommendations to prevent such incidents. (+info)