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At least 109 records · Page 6Linked to original sources
PubMed1985

Ventilatory muscle function during exercise in air and oxygen in patients with chronic air-flow limitation.

Ventilatory muscle function was examined at rest and during exercise on a cycle ergometer in 8 patients with moderate to severe chronic air-flow limitation (FEV1, 32 +/- 4% predicted) in air and in oxygen. The diaphragmatic electromyogram (EMG) was measured using an esophageal electrode. In addition, measurements of esophageal (Pes), gastric (Pga), and transdiaphragmatic (Pdi) pressures and abdominal wall movements were made. Patients exercised to exhaustion at a constant submaximal workload (80% of maximal power output) inspiring air or 40% O2 in random order on separate days. At end-exercise in air, tidal inspiratory Pes swings were 36 +/- 4% of static maximal inspiratory Pes, and inspiratory Pdi swings were 45 +/- 7% of the static maximal Pdi. Arterial oxygen saturation decreased from 91 +/- 2% at rest to 80 +/- 5% at end-exercise in air. During exercise in air, 5 patients demonstrated a persistent and greater than 20% fall in the ratio of high frequency (150 to 350 Hz) to low frequency (20 to 46 Hz) power (H/L) of the diaphragmatic EMG, indicating impending diaphragmatic fatigue, and 2 patients had paradoxical motion of the abdominal wall. Exercise time at the same constant work load increased from 3.0 +/- 0.6 min in air to 6.4 +/- 1.2 min in O2 (p less than 0.005). At the comparable time during exercise in O2 to end-exercise in air, minute ventilation was less by 13% (p less than 0.005), which was entirely attributable to a lower frequency of breathing. Mean inspiratory and expiratory flows and heart rate were all significantly lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1998

Validation of air as an equilibration medium in gastric tonometry: an in vitro evaluation of two techniques for measuring air PCO2.

This laboratory-based bench study was undertaken to evaluate the accuracy and equilibration characteristics of air and saline respectively as CO2 equilibrating media in the silicone balloon of a gastric tonometer and to compare two methods of measuring air PCO2. Two gastric tonometers were suspended in a bath containing 0.9% saline maintained at 37 degrees C. Certified calibration gases at three different CO2 concentrations were bubbled into the bath. When the bath PCO2 measurement was stable the tonometers were primed with 5 ml of air and 2.5 ml normal saline respectively and allowed to equilibrate for 30 and 90 minutes. Following equilibration, samples were aspirated and analysed in duplicate in a blood gas analyser. Bias and precision were calculated from the measured and expected PCO2 values. A consistent negative bias (21-23%) was seen with air at all three CO2 concentrations at 30 and 90 minutes with a coefficient of variation between 2.7 and 3.3%. Imprecise data were obtained with saline at different levels of CO2. A similar experimental set-up was used to compare air PCO2 measurement by a blood gas analyser and an infra-red analyser (Tonocap). Similar bias was obtained with the blood gas analyser with respect to air PCO2 measurement as in experiment 1. The infra-red analyser measurement was highly precise with negligible bias. Air appears to be a better CO2 equilibration medium during bench testing of tonometry producing a systematic negative offset and requiring a uniform correction factor of 1.25. This correction factor is independent of equilibration time and equilibrating CO2 concentration. The use of the infra-red analyser eliminates any bias in the measurement of air PCO2 and obviates the need for a correction factor.

Air↗
PubMed1975

Experimentally determined tissue air ratios and scatter air ratios for collimated beams of 14 mev neutrons.

Tissue air ratios (TAR) and scatter air ratios (SAR) for collimated beams of 14 MeV neutrons were determined from depth dose curves measured in air and water using a tissue equivalent proportional counter. Central axis depth dose data were obtained as a function of field size and depth in a water phantom for an SSD or 125 cm. The collimator was composed of steel and polyethylene and was continuously variable from a 3 times 3 cm to a 20 times 20 cm field size at 125 cm SSD. The field scans for this collimator were flat within plus or minus 2 per cent over 80 per cent of the field dimension in air and were reduced to 20 per cent of the central axis dose at 1-2 field radii in air. Relative depth dose data in air and phantom were measured with an accuracy of plus or minus 2 per cent and were used for the TAR and SAR calculations. The resulting scatter air ratios for 14 MeV neutrons have roughly the same characteristics as 60-Co SAR, but are 60 per cent larger at maximum build-up and reach that maximum at about 60 per cent of the peak depth for 60-Co for all field sizes. The effects of collimator throat scatter on the central axis depth dose characteristics of this particular collimator design are discussed in detail using the measured tissue and scatter air ratios.

Absorption↗
PubMed1975

An epidemiologic approach to community air lead exposure using personal air samplers.

Accurate information on the relationship between blood lead and air lead is essential to any consideration of the possible effect of air lead on the body burden. Past studies of occupationally exposed workers have established that such a relationship exists at high levels of air lead exposure. No such information has been available for subjects exposed to the low air lead levels representative of present-day community exposure. Past studies in this area have suffered from inadequate information on actual lead exposure at the air lead levels of concern. Researchers have has to rely on air lead data obtained from stationary samp;ing stations. Because wide variations can exist betwween locations within a city such information could not be assumed to represent the exposure of any individual subject. At lbest they can be considered only approximations of actual exposures. The Naational Research Council recognized the deficiencies of past studies in their report "Airborne lead in perspective" and recommended that "more precise studies are needed of the relation between atmospheric lead in the urban environment and the concentration of lead in the blood, perphaps by the use of personal monitors". This paper describes the study which was undertaken to evaluate the effect of air lead exposure as measured with personal air sampling devices on indices of lead absorption such as blood lead, urine lead, DALA and ALAD activity...

Absorption↗
PubMed1980

[Investigations on the concentration of air-borne germs in conventionally air-conditioned operating theaters (author's transl)].

The factors influencing the concentration of air-borne bacteria during operations have been analysed. It was found that the concentration of air-borne bacteria depended primarily on the number of persons present in the operating theater, the air exchange rate per hour and the room volume. Persons with sterile dress were found to have much less influence than did persons with unsterile dress. A formula describing the relationship between the average concentration of air-borne germs in operating theaters, the number of persons in sterile and unsterile dress, the air exchange rate and the room volume was derived. In a total of 142 operations, the formula has been found to give reliable estimates of the concentration of air-borne germs. This equation can be used for testing whether or not the concentration of air-borne bacteria in an operating theater is within acceptable limits which have been defined.

Air Conditioning↗
PubMed1987

Somatosensory evoked potentials elicited by air-puff stimuli generated by a new high-speed air control system.

Sharp-fronted air-puffs (a rise-time of 1 msec) generated by the new high-speed air control system were used for eliciting SEPs. This system employs a rotating disk driven by a synchronous electric motor for high-speed control of air flow from a compressed air source. The air-puff is reproducible and its pressure wave form can be varied. SEPs to air-puffs or electrical stimulations of the right hand recorded from the contralateral parietal scalp had similar wave forms, but SEPs to air-puffs showed longer latencies (1-4 msec) and smaller amplitudes than those to electrical stimuli. The amplitude of early components in air-puff SEPs was on average 30% of that in electrical SEPs, but later components reached up to about 90%.

Adolescent↗
PubMedDate not supplied

An evaluation of an air-supplied blouse and an air hood.

Fit factor studies for an air-supplied blouse (blouse) and an air hood respirator (air hood) were conducted by Lawrence Livermore National Laboratory. Nine test subjects were used to test the blouse. Three subjects were used to test the air hood. Exercises conducted in the test chamber included touching toes, raising both arms overhead, squatting, twisting at the torso while holding a rod, and running in place. Both the air hood and blouse were tested with 8 ft3/min air supply. Both respirators were worn in a test chamber. The blouse provided a fit factor of greater than 40,000. The air hood, for nearly all tests, also provided a fit factor greater than 40,000 when worn correctly. Fit factors were also measured for improperly worn air hoods.

Evaluation Studies as Topic↗
PubMed1997

People can detect poor air quality well below guideline concentrations: a prevalence study of annoyance reactions and air pollution from traffic.

OBJECTIVES: Motor vehicle exhaust fumes are the main source of atmospheric pollution in cities in industrialised countries. They cause respiratory disease and annoy people exposed to them. The relation between ambient exposure to air pollution mainly from motor vehicles and annoyance reactions in a general population was assessed. Also, the importance of factors such as age, sex, respiratory disease, access to the use of a car, and smoking habits on the reporting of these reactions was studied. METHODS: A postal questionnaire was sent out in 55 urban areas in Sweden that had nearly identical air quality monitoring stations of the urban air monitoring network. From each area, 150 people aged 16-70 were randomly selected. The questionnaire contained questions on perception of air quality as well as a question on how often exhaust fumes were annoying. RESULTS: Six-monthly nitrogen dioxide concentrations correlated consistently with the prevalence of reported annoyance related to air pollution and traffic exhaust fumes. Black smoke and sulphur dioxide had no significant effects. The frequency of reporting annoyance reactions was higher among people with asthma, women, and people with lack of access to a car. CONCLUSIONS: In this study town dwellers could detect poor air quality at concentrations well below current guidelines for outdoor air pollution. This suggests that questionnaire studies have a place in monitoring air quality.

Adolescent↗
PubMed1991

Prescriptive eyeglass use by U.S. Navy jet pilots: effects on air-to-air target detection.

Air-to-air target detection distances, age, career jet flight hours, and total career flight hours were obtained for 167 U.S. Navy fighter pilots participating in air combat maneuver training at Naval Air Station, Oceana, VA. Of the pilots sampled, 22 used a prescribed spectacle correction while flying; 145 did not. We compared the air-to-air target detection distances between the two groups of pilots, those with corrective glasses and those without. Sunglasses and tinted filters were not factors in the present study. The results strongly suggest that, as a group, the pilots without glasses were able to detect targets at a greater distance than the pilots with glasses. When the pilots were matched on the basis of age and flight experience, the difference in air-to-air target detection capabilities of the two groups increased. The pilots without glasses were able to detect their adversary at a distance more than 20% farther than the pilots with glasses.

Adult↗
PubMed1979

The effect of air ionization on the air-borne transmission of experimental Newcastle disease virus infections in chickens.

The effect of artificial air-ionization on air-borne transmission of Newcastle disease virus (NDV) infection in chickens was studied in an isolated system consisting of two side-by-side cages with solid walls and a wire-gauze roof. During a 3-week observation period more than 90% of the uninoculated indicator chickens, housed in one of the cages, contracted the virus shed to the air by the NDV-inoculated, diseased birds in the neighbouring cage. This air-borne transmission of NDV was completely prevented by increasing the ion concentration in the test room by a constant negative corona discharge above the wire-gauze roof. On the other hand, spreading of the infection within a group of chickens housed in a single cage was not affected by air ionization. These and other results suggest that artificial air-ionization may protect animals from certain air-borne infections by interfering with microbial aerosol formation and/or by facilitating their decay.

Air Ionization↗
PubMedDate not supplied

Compressed-air power tools in orthopaedic surgery: exhaust air is a potential source of contamination.

OBJECTIVES: To determine if the exhaust from surgical compressed-air power tools contains bacteria and if the exhaust leads to contamination of sterile surfaces. DESIGN: Bacteriologic study of orthopaedic power tools. SETTING: Level I trauma center operative theater. PATIENTS/PARTICIPANTS: None. INTERVENTION: Part I. Exhaust from two sterile compact air drills was sampled directly at the exhaust port. Part II. Exhaust from the drills was directed at sterile agar plates from varying distances. The agar plates represented sterile surfaces within the operative field. Part III. Control cultures. A battery-powered drill was operated over open agar plates in similar fashion as the compressed-air drills. Agar plates left open in the operative theater served as controls to rule out atmospheric contamination. Random cultures were taken from agar plates, gloves, drills, and hoses. MAIN OUTCOME MEASUREMENT: Incidence of positive cultures. RESULTS: In Part I, all filters from both compressed-air drill exhausts were culture negative ( = 0.008). In Part II, the incidence of positive cultures for air drills number one and number two was 73% and 82%, respectively. The most commonly encountered organisms were, coagulase-negative Staphylococcus, and Micrococcus species. All control cultures from agar plates, battery-powered drill, gloves, and hoses were negative ( < 0.01). CONCLUSIONS: Exhaust from compressed-air power tools in orthopaedic surgery may contribute to the dissemination of bacteria onto the surgical field. We do not recommend the use of compressed-air power tools that do not have a contained exhaust.

Air Microbiology↗
PubMed1992

Presence of viable mould propagules in indoor air in relation to house damp and outdoor air.

The presence of viable mould propagules in indoor air was investigated using the N6-Andersen sampler in combination with DG18-agar, in relation to house damp (characterized with a checklist) and in relation to the presence of moulds in outdoor air. The first part of the study was conducted in 46 houses in the autumn of 1987, the second part in 84 houses in May 1989. Further, in the second part, the results obtained with settlement plates (OPD) were compared with those obtained with the N6-Andersen sampler. The number of CFU/m3 in the indoor and outdoor air varied widely. A large variety of mould genera and species was isolated. Species of Cladosporium, Penicillium and Wallemia predominated. The variability in time was high and the reproducibility of the measurements in terms of CFU/m3 and of species isolated was only moderate. The low predictive value of these measurements limits their use in epidemiological studies of the relationship between exposure to moulds and respiratory symptoms. Overall, the geometric mean concentration was somewhat higher outdoors than indoors. However, the clear differences found between the number of CFU/m3 belonging to different mould species in in- and outdoor air show that the presence of viable mould propagules in indoor air is not simply a reflection of the presence of moulds in outdoor air. The presence of moulds in indoor air was only weakly related to house damp as characterized by the checklist. High, statistically significant correlations were found between the CFU yield obtained with the OPD and the CFU/m3 yield obtained with the N6-Andersen sampler.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗
PubMed1988

Relationship of blood protein levels to outdoor air pollutant concentrations in a semicohort of school-age children living in urban areas differing by quality of air.

Variations in some humoral immune responses to polluted air were studied in two semicohorts of children, initial age 10 years, from two urban communities differing from each other by the degree of ambient air pollution. The material for analysis (blood, saliva) was collected every autumn and spring in 3 successive years, giving a total of 6 sets of specimens for each examinee. All blood specimens were examined for the serum level of immunoglobulins (IgG, IgA, IgM), lysozyme (LYS), total serum protein (TP) and the level of the acute reactants alpha 2 macroglobulin (A2M), alpha 1 antitrypsin (A1AT), transferrin (TRF) and ceruloplasmin (CPL). The saliva specimens were examined for the level of lysozyme (sLYS) and secretory IgA (sIgA). The mean protein concentrations for each of the 6 sampling series were correlated with the mean of 24-h emission concentrations measured in the last 3 months preceding the autumn or spring sampling series. In the community area characterized by a low-degree non-industrial pollution of air the correlations of immunoglobulins to SO2 and floating particles (FP) in air were as a rule inversed while the response from TP, LYS and acute reactants was direct. In the community contaminated by industrial pollutants, correlations between proteins and SO2 were markedly weaker, but there was a significant positive correlation between H2S and levels of IgA and A2M in blood and sIgA and sLYS in the saliva. A high degree of positive correlation was also observed between H2S and levels of IgM and LYS. Inverse correlations were only between levels of LYS and FP, SO2 and H2S. Significant correlations were also between contaminant concentrations and FP. The associations found between the contaminant concentrations in air and levels of blood and saliva proteins supports the hypothesis that quality of air may have considerable impacts on defense mechanisms. Seasonal variations in the quality of air may increase the rates of childhood morbidity for acute upper respiratory tract infections.

Acute-Phase Proteins↗
PubMed1999

Cloning of Aire, the mouse homologue of the autoimmune regulator (AIRE) gene responsible for autoimmune polyglandular syndrome type 1 (ASP1).

The human autoimmune regulator gene (AIRE), responsible for autoimmune polyglandular syndrome Type 1 (APS1), has recently been identified by positional cloning. Here we report the cloning of Aire, the mouse homologue of AIRE, and the characterization of its genomic structure. The complete Aire gene is contained in 14 exons and encodes a protein of 552 amino acids. The coding region shares 77% nucleotide homology and 71% protein homology with human AIRE. As in its human homologue, Aire contains two PHD-type zinc-finger motifs, suggesting that the Aire protein may act as a transcription regulator.

Amino Acid Sequence↗
PubMed2005

Can we use fixed ambient air monitors to estimate population long-term exposure to air pollutants? The case of spatial variability in the Genotox ER study.

Associations between average total personal exposures to PM2.5, PM10, and NO2 and concomitant outdoor concentrations were assessed within the framework of the Genotox ER study. It was carried out in four French metropolitan areas (Grenoble, Paris, Rouen, and Strasbourg) with the participation, in each site, of 60-90 nonsmoking volunteers composed of two groups of equal size (adults and children) who carried the personal Harvard Chempass multipollutant sampler during 48 h along two different seasons ("hot" and "cold"). In each center, volunteers were selected so as to live (home and work/school) in three different urban sectors contrasted in terms of air pollution (one highly exposed to traffic emissions, one influenced by local industrial sources, and a background urban environment). In parallel to personal exposure measurements, a fixed ambient air monitoring station surveyed the same pollutants in each local sector. A linear regression model was accommodated where the dependent pollutant-specific variable was the difference, for each subject, between the average ambient air concentrations over 48 h and the personal exposure over the same period. The explanatory variables were the metropolitan areas, the three urban sectors, season, and age group. While average exposures to particles were underestimated by outdoor monitors, in almost all cities, seasons, and age groups, differences were lower for NO2 and, in general, in the other direction. Relationships between average total personal exposures and ambient air levels varied across metropolitan areas and local urban sectors. These results suggest that using ambient air concentrations to assess average exposure of populations, in epidemiological studies of long-term effects or in a risk assessment setting, calls for some caution. Comparison of personal exposures to PM or NO2 with ambient air levels is inherently disturbed by indoor sources and activities patterns. Discrepancies between measurement devices and local and regional sources of pollution may also strongly influence how the ambient air concentrations relate to population exposure. Much attention should be given to the selection of the most appropriate monitoring sites according to the study objectives.

Adult↗
PubMedDate not supplied

Quality of air contrast barium enema performed the same day as incomplete colonoscopy with air insufflation.

The quality of 17 air contrast barium enemas performed the same day as incomplete colonoscopies using air insufflation was compared with 21 air contrast barium enemas performed on a different day from incomplete colonoscopies. A gastrointestinal radiologist blinded to the timing of the procedures reviewed the barium studies scoring them as 1 (unsatisfactory) to 4 (excellent) in four areas. The mean overall quality score for the air contrast barium enemas done the same day as incomplete colonoscopy was 3.29 vs. 2.97 for those done on a different day (p = 0.24). There were no significant differences in quality scores between same-day versus different-day air contrast barium enemas for the specific parameters of quality of distention, barium coating, and amount of spasm. We conclude that when colonoscopy using air insufflation is incomplete because of looping or angulation, air contrast barium enema can be done the same day without impairing the quality of the barium study.

Air↗
PubMed1994

A review of drug use during air medical transport to optimize an air ambulance formulary.

INTRODUCTION: The advent of air medical transport has pushed the delivery of critical care medicine into the prehospital arena. As a result, a wide variety of pharmacologic agents must be available in the air medical setting. PURPOSE: The purpose of this study was to conduct a retrospective review of drugs used during air medical transport to allow a streamlining of the air ambulance formulary. METHODS: All flights completed since the inception of the study's helicopter air ambulance program in 1985 through September 1991 were analyzed to determine which medications were used in flight. Drugs were counted if they were administered while in flight for either a scene or interhospital transport. RESULTS: Review of 2,694 flights showed that 45 individual drugs had been routinely carried during the study period. Many of these agents were administered fewer than five times during the six years, and 10 drugs were not used at all. CONCLUSION: As a result of this investigation, the formulary for our air medical transport service was modified. The authors recommend similar critical audits of drugs carried in flight be performed by other air ambulance services.

Air Ambulances↗
PubMed2006

Air contaminants in a submarine equipped with air independent propulsion.

The Swedish Navy has operated submarines equipped with air independent propulsion for two decades. This type of submarine can stay submerged for periods far longer than other non-nuclear submarines are capable of. The air quality during longer periods of submersion has so far not been thoroughly investigated. This study presents results for a number of air quality parameters obtained during more than one week of continuous submerged operation. The measured parameters are pressure, temperature, relative humidity, oxygen, carbon dioxide, hydrogen, formaldehyde and other volatile organic compounds, ozone, nitrogen dioxide, particulate matter and microbiological contaminants. The measurements of airborne particles demonstrate that air pollutants typically occur at a low baseline level due to high air exchange rates and efficient air-cleaning devices. However, short-lived peaks with comparatively high concentrations occur, several of the sources for these have been identified. The concentrations of the pollutants measured in this study do not indicate a build-up of hazardous compounds during eight days of submersion. It is reasonable to assume that a substantial build-up of the investigated contaminants is not likely if the submersion period is prolonged several times, which is the case for modern submarines equipped with air independent propulsion.

Air Pollutants, Occupational↗