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PubMed1999

Tropospheric Aerosol Climate Forcing in Clear-Sky Satellite Observations over the Oceans.

Tropospheric aerosols affect the radiative forcing of Earth's climate, but their variable concentrations complicate an understanding of their global influence. Model-based estimates of aerosol distributions helped reveal spatial patterns indicative of the presence of tropospheric aerosols in the satellite-observed clear-sky solar radiation budget over the world's oceans. The results show that, although geographical signatures due to both natural and anthropogenic aerosols are manifest in the satellite observations, the naturally occurring sea-salt is the leading aerosol contributor to the global-mean clear-sky radiation balance over oceans.

Journal Article↗
PubMed1971

Inhibition of respiratory virus infections of mice with aerosols of synthetic double-stranded ribonucleic Acid.

Aerosols of double-stranded complexes of polyinosinic and polycytidylic acids (poly I:C) were useful in protecting mice infected with aerosols of influenza (A(2)/Taiwan/64) and parainfluenza type 1 (Sendai) viruses. Administration of poly I:C as an aerosol offers an advantage, particularly in therapy, by eliminating the risk of pulmonary dissemination of viral infections due to intranasally instilled fluids. Treatment of mice with aerosols of poly I:C reduced the infection rate with influenza virus but did not inhibit virus multiplication in the lungs of most of those animals where infection became established. Sendai virus infection rates were undiminished in mice treated with poly I:C, but lung-virus titers were significantly suppressed as compared with those of untreated animals. The maximum poly I:C doses (40 mug) administered by aerosol produced no evidence of toxicity in the mice.

Journal Article↗
PubMed1997

Aerosol kinetics and bronchodilator efficacy during continuous positive airway pressure delivered by face mask.

BACKGROUND: Rates of fresh gas flow (FGF) commonly used when continuous positive airway pressure (CPAP) is delivered by face mask theoretically reduce the delivery and availability of therapeutic aerosols. As it may be hazardous for patients with acute respiratory failure to interrupt mask CPAP, the effects of CPAP on aerosol kinetics and bronchodilator efficacy were investigated. METHOD: The effect of CPAP at 10 cm H2O at a FGF rate of 50 l/min on the delivery of technetium labelled aerosol generated from a readily available jet nebuliser was measured using a bench model of spontaneous respiration. In a separate clinical study the bronchodilator responses to incremental doses of nebulised salbutamol were measured in nine stable asthmatic subjects in a random sequence of conventional nebulisation (control) or nebulisation whilst receiving CPAP via a tight fitting face mask. Each patient acted as his or her own control. RESULTS: CPAP significantly reduced total aerosol delivery to the face mask from 6.85 (1.52)% to 1.3 (0.37)% of the initial nebuliser charge. In the clinical study a significant bronchodilator response to nebulised salbutamol was seen during both conventional nebulisation and nebulisation whilst receiving CPAP by face mask. The shape of the dose-response curves and the magnitude of the total increase in the forced expiratory volume in one second (FEV1) was identical for CPAP and control conditions. CONCLUSIONS: Despite a reduction in aerosol presented to the proximal airway, the bronchodilator response to inhaled beta 2 agonists in stable asthmatic subjects was not affected when CPAP was delivered by face mask. Despite a high rate of FGF, nebulised beta 2 agonists are effective when administered in conjunction with CPAP delivered by face mask.

Adult↗
PubMed1990

Immunoglobulin E responses and lung pathology resulting from aerosol exposure of calves to respiratory syncytial virus and Micropolyspora faeni.

Bovine respiratory syncytial virus (BRSV) infection of calves has been associated with a type-I hypersensitivity syndrome not unlike respiratory syncytial virus-associated pulmonary symptomatology in humans. To study the mechanism of pulmonary pathology in calves and define the relationship with both viral-specific IgE response and IgE titers to concurrent aerosol of Micropolyspora faeni (Mf) we subjected groups of calves to inhalation of Mf during acute BRSV infection. The calves were divided into 4 groups: exposed to virus only (group 1); exposed to aerosolized Mf over a 24-day period and then challenged with Mf during BRSV infection (group 2); similarly exposed to aerosolized Mf and then challenged with Mf without BRSV infection (group 3) and exposed to aerosolized Mf, infected with virus but not challenged with Mf (group 4). All calves were followed for appearance of IgE-specific responses to both BRSV and Mf, clinical disease expression, and pulmonary pathology including viral and allergen localization by immunohistology. Our data indicate an association of BRSV-specific IgE with increased development of lung pathology and clinical disease expression and an enhancing effect of aerosolized Mf on induction of virus-specific IgE. The presence of BRSV-specific IgE was solely in calves with the most significant macroscopic and microscopic pneumonic lesions.

Actinomycetales Infections↗
PubMed1992

Effects of aerosolized dexamethasone on acute subglottic injury.

Aerosolized dexamethasone was used in a two-phase study to determine the possible effects on acute subglottic injury in the ferret animal model. In phase 1, equivalent subglottic injuries were made in 10 animals by using the brush technique, and the animals were divided into two groups. The treatment group received aerosolized dexamethasone at 2, 4, and 6 hours postinjury. All animals were examined 2, 4, 6, and 24 hours after the injury. The clinical condition of each animal was evaluated and their airways were measured. The animals were then painlessly killed and the larynges were frozen, sectioned, and photographed at 1-mm intervals. A computer-linked digitizer pad was used to measure the subglottic dimensions. The results show a trend for the treated animals to have a larger subglottic airway as compared to the untreated (control) group. The phase 1 study suggests that there may be an improvement in the subglottic airway when treated acutely with aerosolized dexamethasone. In phase 2, 20 additional animals were studied by using the same methods of injury and treatment as in phase 1. The subglottic airways of these animals were evaluated with histomorphometric analysis on fixed histologic sections. A statistically significant difference was found between the subglottic airways of the treated and untreated animals favoring treatment with aerosolized dexamethasone. Aerosolized dexamethasone appears to be beneficial in preserving the subglottic airway after injury, possibly secondary to decreasing the edema associated with injury.

Acute Disease↗
PubMed1989

Characterization and reconstruction of historical London, England, acidic aerosol concentrations.

Several past studies of the historical London air pollution record have reported an association between daily mortality and British Smoke levels. However, this pollution index does not give direct information on particulate mass or its chemical composition. A more specific particulate matter index, aerosol acidity, was measured at a site in central London, and daily data are available for the period 1963-1972. British Smoke and SO2 were also measured at the same site. Also, meteorological parameters were routinely measured at a nearby British Meteorological Office. Thus, daily fluctuation of the acidic aerosols was characterized in terms of other environmental parameters. Each of the other parameters analyzed seems necessary, but not sufficient to explain a high level of acidic aerosol. Overall, about half of the variance of log-transformed daily fluctuations of acidic aerosols can be explained by a combination of parameters including SO2 and British Smoke concentrations, temperature, ventilation by wind, and humidity. The rest of the variance cannot be explained by the parameters included in this analysis. Potential factors responsible for this unique variance would be variations in the availability of basic gases to cause neutralization and variation in the availability of catalytic metal salts. Because the acidic aerosol has a unique component of variation, it may be possible to distinguish health effects due to this specific pollutant from other available pollution indices or environmental factors.

Acid Rain↗
PubMed2002

Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. II. Comparison of extinction, reflectance, polarization, and counting measurements.

The physical properties of stratospheric aerosols can be retrieved from optical measurements involving extinction, radiance, polarization, and counting. We present here the results of measurements from the balloonborne instruments AMON, SALOMON, and RADIBAL, and from the French Laboratoire de Météorologie Dynamique and the University of Wyoming balloonborne particle counters. A cross comparison of the measurements was made for observations of background aerosols conducted during the polar winters of February 1997 and January-February 2000 for various altitudes from 13 to 19 km. On the one band, the effective radius and the total amount of background aerosols derived from the various sets of data are similar and are in agreement with pre-Pinatubo values. On the other hand, strong discrepancies occur in the shapes of the bimodal size distributions obtained from analysis of the raw measurement of the various instruments. It seems then that the log-normal assumption cannot fully reproduce the size distribution of background aerosols. The effect ofthe presence of particular aerosols on the measurements is discussed, and a new strategy for observations is proposed.

Journal Article↗
PubMed2005

Simultaneous stratospheric gas and aerosol retrievals from broadband infrared occultation measurements.

The inversion method for simultaneous gas (O3, NO2, HNO3, N2O, CH4, H2O, CFC-11, CFC-12, N2O5, and ClONO2) and aerosol retrievals from broadband continuous IR spectra of occultation measurements is described. Both gas and aerosol physical modeling with consideration of the multicomponent character of aerosol and polar stratospheric clouds (PSCs) are used to minimize the difference between measured and modeled transmittance spectra under smoothness constraints imposed on particle-size distributions for each PSC component and positive constraints on all gas and aerosol parameters. The method is tested by numerical simulations in which synthetic occultation measurements inherent to the improved limb atmospheric spectrometer are used. The study reveals that the method has significant advantages over other approaches based on offset or gas-window-channel aerosol correction for accurate gas retrievals and provides additional information on the particle-size composition, volume density, and chemical component character of PSCs.

Journal Article↗
PubMed2006

Aerosol extinction models based on measurements at two sites in Sweden.

Two aerosol extinction models have been developed using statistical analysis of long-term optical transmission measurements in Sweden performed at two locations from July 1977 to June 1982. The aerosol volume extinction coefficient for infrared (IR) radiation is calculated by the models with visibility, temperature, and air pressure as input parameters. As in the MODTRAN model, the IR extinction coefficient is proportional to the coefficient at 550 nm, which depends on the visibility. In the new models, the wavelength dependence of the extinction also depends on the visibility. The models predict significantly higher attenuation in the IR than does the Rural aerosol model from MODTRAN, which is commonly used. Comparison with the Maritime model shows that the new models predict lower extinction values in the 3-5 microm region and higher values in the 8-12 microm region. The uncertainties in terms of variance levels are calculated by the models. The properties of aerosols, and thereby the extinction coefficient, are partly correlated to local meteorological parameters, which enables the calculation of a mean predicted value. A substantial part of the variation is, however, caused by conditions in the source area and along the trajectory path of the aerosols. They are not correlated to the local meteorological parameters and therefore cause the variance in the models.

Journal Article↗
PubMed2006

Characteristics of dust aerosols inferred from lidar depolarization measurements at two wavelengths.

Lidar depolarization measurements were performed simultaneously at two wavelengths (532 and 1064 nm) in an Asian dust event. The observed particle depolarization ratio for 1064 nm was generally larger than that for 532 nm, and it was found that the mixing of Asian dust and other spherical aerosols must be taken into account. A simple two-component theory considering two types of aerosol (dust and spherical aerosols) was developed and applied to the observed data. The mixing ratio of dust and the backscatter-related Angström exponents for dust and spherical aerosols was derived. These parameters can be used to infer characteristics of the aerosols and the mixed states.

Journal Article↗
PubMed2006

Effect of aerosol microphysical properties on polarization of skylight: sensitivity study and measurements.

We analyze the sensitivity of the degree of linear polarization in the Sun's principal plane as a function of aerosol microphysical parameters: the real and imaginary parts of the refractive index, the median radius and geometric standard deviation of the bimodal size distribution (both fine and coarse modes), and the relative number weight of the fine mode at a wavelength of 675 nm. We use Mie theory for single-scattering simulations and the doubling-adding method with the inclusion of polarization for multiple scattering. It is shown that the behavior of the degree of linear polarization is highly sensitive to both the small mode of the bimodal size distribution and the real part of the refractive index of aerosols, as well as to the aerosol optical thickness; whereas not all parameters influence the polarization equally. A classification of the importance of the input parameters is given. This sensitivity study is applied to an analysis of ground-based polarization measurements. For the passive remote sensing of microphysical and optical properties of aerosols, a ground-based spectral polarization measuring system was built, which aims to measure the Stokes parameters I, Q, and U in the visible (from 410 to 789 nm) and near-infrared (from 674 to 995 nm) spectral range with a spectral resolution of 7 nm in the visible and 2.4 nm in the near infrared. We compare polarization measurements taken with radiative transfer simulations under both clear- and hazy-sky conditions in an urban area (Cabauw, The Netherlands, 51.58 degrees N, 4.56 degrees E). Conclusions about the microphysical properties of aerosol are drawn from the comparison.

Journal Article↗
PubMed2005

Device selection and outcomes of aerosol therapy: Evidence-based guidelines: American College of Chest Physicians/American College of Asthma, Allergy, and Immunology.

BACKGROUND: The proliferation of inhaler devices has resulted in a confusing number of choices for clinicians who are selecting a delivery device for aerosol therapy. There are advantages and disadvantages associated with each device category. Evidence-based guidelines for the selection of the appropriate aerosol delivery device in specific clinical settings are needed. AIM: (1) To compare the efficacy and adverse effects of treatment using nebulizers vs pressurized metered-dose inhalers (MDIs) with or without a spacer/holding chamber vs dry powder inhalers (DPIs) as delivery systems for beta-agonists, anticholinergic agents, and corticosteroids for several commonly encountered clinical settings and patient populations, and (2) to provide recommendations to clinicians to aid them in selecting a particular aerosol delivery device for their patients. METHODS: A systematic review of pertinent randomized, controlled clinical trials (RCTs) was undertaken using MEDLINE, EmBase, and the Cochrane Library databases. A broad search strategy was chosen, combining terms related to aerosol devices or drugs with the diseases of interest in various patient groups and clinical settings. Only RCTs in which the same drug was administered with different devices were included. RCTs (394 trials) assessing inhaled corticosteroid, beta2-agonist, and anticholinergic agents delivered by an MDI, an MDI with a spacer/holding chamber, a nebulizer, or a DPI were identified for the years 1982 to 2001. A total of 254 outcomes were tabulated. Of the 131 studies that met the eligibility criteria, only 59 (primarily those that tested beta2-agonists) proved to have useable data. RESULTS: None of the pooled metaanalyses showed a significant difference between devices in any efficacy outcome in any patient group for each of the clinical settings that was investigated. The adverse effects that were reported were minimal and were related to the increased drug dose that was delivered. Each of the delivery devices provided similar outcomes in patients using the correct technique for inhalation. CONCLUSIONS: Devices used for the delivery of bronchodilators and steroids can be equally efficacious. When selecting an aerosol delivery device for patients with asthma and COPD, the following should be considered: device/drug availability; clinical setting; patient age and the ability to use the selected device correctly; device use with multiple medications; cost and reimbursement; drug administration time; convenience in both outpatient and inpatient settings; and physician and patient preference.

Adrenergic beta-Agonists↗
PubMed2001

Treatment of ulcerative endobronchial tuberculosis and bronchial stenosis with aerosolized streptomycin and steroids.

OBJECTIVES: Endobronchial tuberculosis (EBTB) is defined as a tuberculous infection of the tracheobronchial tree. It has been reported that aerosolized therapy with streptomycin and steroids is useful for EBTB; however, the effectiveness of this therapy for bronchial stenosis has yet to be clarified. This study was undertaken to determine the effectiveness of aerosol therapy in the treatment of bronchial stenosis due to EBTB. DESIGN: An observational, historical, controlled comparative study. Retrospective analysis of 27 patients treated with conventional therapy, and prospective analysis of 30 patients treated with aerosol therapy. METHOD AND PATIENTS: Flexible bronchoscopy was performed at least twice in 57 patients with ulcerative EBTB, in whom the degree of bronchial stenosis between the first and last bronchoscopic examinations was estimated. Bronchial stenosis was graded as minimal, mild, moderate, severe or obstructive, and the follow-up of bronchial stenosis assessed as aggravation, no change or improvement. RESULTS: Conventional therapies led to aggravation in 13 patients, no change in 13 patients, and improvement in one patient. Aerosol therapy led to no change in 27 patients, and improvement in three patients. No patients developed aggravation. The differences between the therapeutic groups were significant. CONCLUSION: Aerosol therapy helps to prevent progressively severe bronchial stenosis due to EBTB.

Administration, Inhalation↗
PubMed1999

[Clinical and experimental study on Yinhua mixture aerosol in treating infantile viral pneumonia].

OBJECTIVE: To explore the therapeutic effect of using Yinhua mixture aerosol in treating infantile viral pneumonia and its mechanism. METHODS: Comparing sixty-nine infantile viral pneumonia patients using Yinhua mixture aerosol with 33 infantile viral pneumonia patients using gentamycin, pharmacodynamical animal experiments of anti-tussis and anti-asthma were also observed. RESULTS: The markedly effective rate of Yinhua mixture aerosol and gentamycin aerosol were 58.0% and 27.3% respectively, while the total effective rate of these two drugs was 95.7% and 69.7% respectively. Experimental study revealed that Yinhua mixture was effective in antifebrile, anti-asthma and expectorative effect, which was better than that of gentamycin (P < 0.05). CONCLUSION: Yinhua mixture aerosol is effective in antifebrile, anti-asthma, and expectorative effect.

Administration, Inhalation↗
PubMed2004

Particle size characterization and the indoor-to-outdoor relationship of atmospheric aerosols in Helsinki.

OBJECTIVES: The influence of traffic and meteorological conditions on aerosol characteristics outdoors, the relationship between indoor and outdoor aerosol particles, and the pollutant transport indoors by means of a mechanical ventilation system were studied. METHODS: Indoor and outdoor concentrations of fine-particle numbers were measured during the summer (15 May--30 June 2000) in one office located in the basement of a building in Helsinki, Finland. The total number concentration was measured with a condensation particle counter, and the particle number size distribution (7-600 nm) was measured with a differential mobility particle sizer. The size distribution (0.3-25 microm) of the indoor particle numbers was periodically measured with a laser particle counter. RESULTS: Meteorological conditions, especially wind direction, had the greatest effect on the total number concentration and the size distribution of aerosol particles outdoors. The outdoor number concentration of ultrafine particles (diameter <100 nm) was strongly dependent on traffic density. The temporal variations in the indoor number concentration of ultrafine and fine particles (7-600 nm) closely followed the corresponding temporal variations outdoors. The building ventilation system was the main means of transporting aerosols indoors. The mean penetration factor was 0.41 (SD 0.11) for the nucleation mode (7-25 nm), 0.74 (SD 0.09) for the Aitken mode (25-100 nm), and 0.87 (SD 0.06) for the accumulation mode (100-600 nm). CONCLUSIONS: The ultrafine particles were bimodal with a nucleation mode (particle diameter <25 nm) and an Aitken mode (25 nm <particle diameter <100 nm). An accumulation mode was observed with a particle diameter larger than 100 nm. The patterns of fine-particulate air pollution inside an office can be largely estimated on the basis of the outdoor aerosol characterization and the mechanical ventilation system.

Air Pollutants↗
PubMed2004

[Preliminary study on the relationship between chronic sinusitis histomorphology and aerosol].

OBJECTIVE: To observe the relationship between histomorphological changes in mucosa of chronic sinusitis (CS) and aerosol particles. METHODS: The ethmoidal sinus mucus specimens of 60 patients with CS type I, II and III, and 16 cases of normal controls were collected. Meanwhile the pulmonary specimens in autopsy of 5 adult and 5 fetus cases were also collected. The specimens were stained by HE staining and Warthin-Starry (W-S) special aerosol particles staining method respectively, the ethmoidal sinus mucosa basement membrane were displayed by Van Gieson's (VG) special staining method, and its thickness was measured. RESULTS: By the W-S staining, some black aerosol particles were found depositing on the epithelial cells layer of damaged mucosa and in the plasm of the epithelial cells. The degree of deposition was gradually increased in type I, II and III of CS. The number of cases of slight, medium and heavy depositing in type I were 11/20, 7/20, 2/20, in type II 5/20, 9/20, 6/20, and in type III 3/20, 6/20, 11/20 respectively; the more particles deposited, the more thickening the basement membrane. The thickness of the basement membrane in type I, II and III of CS were (12.15 +/- 4.73), (16.67 +/- 2.22), (23.75 +/- 3.48) microm respectively. There were significant differences among type I, II and III (P < 0.01). The black particles in the mucosa epithelium tissues of normal control group and non-damaged mucosa epithelium and desquamation area were seldom seen. On the other hand, the aerosol particles were not seen in the pulmonary specimens of the fetal autopsy. CONCLUSION: In damaged mucosa epithelial cells of the CS, there are aerosol particles existing which may relate with the morphological changes of CS.

Adolescent↗
PubMed2006

The impact of animal age, bacterial coinfection, and isolate pathogenicity on the shedding of porcine reproductive and respiratory syndrome virus in aerosols from experimentally infected pigs.

The objective of this study was to evaluate the role of different variables (animal age, bacterial coinfection, and isolate pathogenicity) on the shedding of Porcine reproductive and respiratory syndrome virus (PRRSV) in aerosols. Animals were grouped according to age (2 versus 6 mo) and inoculated with a PRRSV isolate of either low (MN-30100) or high (MN-184) pathogenicity. Selected animals in each group were also inoculated with Mycoplasma hyopneumoniae. The pigs were anesthetized and aerosol samples (1000 breaths/sample) collected on alternating days from 1 to 21 after PRRSV inoculation. The results indicated that animal age (P = 0.09), M. hyopneumoniae coinfection (P = 0.09), and PRRSV isolate pathogenicity (P = 0.15) did not significantly influence the concentration of PRRSV in aerosols. However, inoculation with the PRRSV MN-184 isolate significantly increased the probability of aerosol shedding (P = 0.00005; odds ratio = 3.22). Therefore, the shedding of PRRSV in aerosols may be isolate-dependent.

Age Factors↗
PubMed1998

Hydrofluoroalkane-134a beclomethasone dipropionate extrafine aerosol provides equivalent asthma control to chlorofluorocarbon beclomethasone dipropionate at approximately half the total daily dose.

The mandatory requirement to eliminate chlorofluorocarbons (CFCs) as propellants in pharmaceutical aerosols has provided the opportunity to enhance significantly the delivery of aerosol drugs to the respiratory tract. This randomized, parallel-group, double-blind, double-dummy, multicentre study was undertaken to assess whether beclomethasone dipropionate (BDP) in hydrofluoroalkane-134a (HFA) provided equivalent control of moderately severe asthma to BDP in CFC but at approximately half the total daily dose, as might be expected from the improved lung deposition of the HFA-BDP extrafine aerosol. The novel study design included a 10-12 day run-in period to confirm that patients met established criteria of moderately severe asthma and were symptomatic on current therapy (inhaled beta-agonist plus CFC-BDP 400-800 micrograms day-1). This run-in period was followed by a short course of oral steroid therapy (prednisolone 30 mg day-1 for 7-13 days) to demonstrate steroid responsiveness [> or = 15% improvement in morning peak expiratory flow (PEF)] and to provide a within-study baseline of improved asthma control. A total of 233 patients were randomized to treatment for 12 weeks with HFA-BDP 800 micrograms day-1 (116 patients) or CFC-BDP 1500 micrograms day-1 (117 patients). The mean change from oral steroid treatment in morning PEF with HFA-BDP was equivalent to that seen with CFC-BDP at all time intervals. Changes in other measures of pulmonary function, asthma symptom scores and beta-agonist use were equivalent in the two treatment groups throughout the 12 week treatment period. The safety profile of HFA-BDP compared favourably with that of CFC-BDP with no unexpected adverse events reported. Fewer patients on HFA-BDP than on CFC-BDP had plasma cortisol levels below the normal reference range after 12 weeks of therapy (5.1% vs. 17.3%, respectively). In conclusion, HFA-BDP extrafine aerosol was found to provide equivalent control of moderately severe asthma to CFC-BDP at approximately half the daily dose with a favourable safety profile, suggesting an improved therapeutic ratio.

Administration, Inhalation↗