Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AEROSOLS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed2002

Observations of aerosol-bound ionic compositions at Cheju Island, Korea.

To investigate the regional cycle of aerosols and their ionic constituents, three field intensive campaigns were conducted during fall and winter of 1997 and spring of 1998. The concentrations of most ionic species were found to decrease significantly across fall, winter, and spring such that the sum for all cation (and anion) species of each season is computed as: 193 > 96 > 73.7 nequiv m(-3) (and 240 > 104 > 51.5 nequiv m(-3)). To examine the fundamental characteristics of aerosol compositions in the study area, we conducted correlation analysis in various manners. The results indicated that the concentrations of major ionic species were strongly affected by some meteorological parameters including wind speed. It was also seen that relative strengths of correlations between important parameters (e.g., between wind speed and most of major inorganic species) maintain close relationships with the factors associated with the air mass origin. In addition, the results of factor analysis indicated the existence of at least three major sources in the study area which include: sea-salt aerosol, secondary aerosol, and organic aerosol component. The springtime occurrence of unexpectedly low concentrations of most ionic constituents is found to sensitively reflect the influence of the inflow of southeasterly winds that prevailed during spring, while it is not common for that season of the year. Because most of those changes are closely tied with the variabilities in the regional circulation patterns for each measurement period, assessment of the ionic composition in concert with the temporal variations of meteorological conditions provided valuable insights into the source signals of different air masses that passed by the study area.

Aerosols↗
PubMed2002

European isotopic signatures for lead in atmospheric aerosols: a source apportionment based upon 206Pb/207Pb ratios.

To investigate the capability of the lead isotope signature technique to support a source apportionment study at a Continental scale, atmospheric particulate matter was collected at Cap Gris-Nez (Eastern Channel, northern France), over one year (1995-1996). Four days retrospective trajectories of air masses were available during each sampling experiment. Twenty-eight samples, for which the origin of aerosols was unambiguously determined, were selected for isotopic measurements. Considering the Enrichment Factors, EF(Crust) of lead and its size distribution, we show that lead is mostly from anthropogenic origin and mainly associated with [0.4 < diameter < 0.9 microm] particles. The extent to which various Continental sources influence the lead abundance in aerosols is exhibited by considering both the lead concentration and the origin of air masses. Lead concentration is higher by a factor of approximately seven, when air masses are derived from Continental Europe, by comparison with marine air masses. Taking into account these concentrations and the vertical movements of air masses, we compare the different isotopic compositions using a statistical non-parametric test (Kolmogorov-Smirnov). We produce evidence that, for most of the cases, air masses originating from Continental Europe exhibit a more radiogenic composition (1.134 < 206Pb/207Pb < 1.172) than air masses coming from the United Kingdom (1.106 < 206Pb/207Pb < 1.124). Generally, lead isotopic compositions in aerosols are clearly distinct from the gasoline signatures in European countries, strongly suggesting that automotive lead is no longer the major component of this metal in the air. Gasoline and industrial isotopic signatures could explain the origin of lead in our aerosol samples. A source apportionment based upon 206Pb/207Pb ratios, suggests that the difference between British (206Pb/207Pb = 1.122 +/- 0.038) and Continental (206Pb/207Pb = 1.155 +/- 0.022) signatures may be largely explained by differences in the petrol lead content of aerosols (23-62% in Great Britain vs. 10-36% in Continental Europe).

Aerosols↗
PubMed2003

Heavy metals in aerosols over the seas of the Russian Arctic.

A review of the data on heavy metals in aerosols over the seas of the Russian Arctic is presented. Results of heavy metal studies in aerosols obtained during 11 research expeditions in summer/autumn period from 1991 to 2000, and at Severnaya Zemlya and Wrangel Island in spring, in 1985-1989 are discussed. Concentrations of most heavy metals in the atmosphere in the marine boundary layer in the Russian Arctic are nearly of the same order as literature data from other Arctic areas. The content of heavy metals in the aerosols over the seas of the Russian Arctic shows an annual variation with maximal concentrations during the winter/spring season. In the summer/autumn period increased concentrations of heavy metals could be explained, in most cases, by natural processes (generation of sea salt aerosols, etc.). In some cases, aerosols from Norilsk and Kola Peninsula were detected. Particular attention was paid to estimation of horizontal and vertical fluxes of atmospheric heavy metals. We estimated annual variations in long-range transport of heavy metals into the Russian Arctic in 1986-1995. In winter and spring, up to 50% of the average air pollutant concentrations in the Russian Arctic are due to the Arctic atmospheric pollution itself. Moreover, the monthly and annual averaged fluxes of six anthropogenic chemical elements (arsenic, nickel, lead, vanadium, zinc and cadmium) onto the surface in the Arctic were estimated, and the values obtained were in reasonable agreement with the literature data available.

Aerosols↗
PubMed1997

Secondary organic aerosols: formation potential and ambient data.

Organic aerosols comprise a significant fraction of the total atmospheric particle loading and are associated with radiative forcing and health impacts. Ambient organic aerosol concentrations contain both a primary and secondary component. Herein, fractional aerosol coefficients (FAC) are used in conjunction with measurements of volatile organic compounds (VOC) to predict the formation potential of secondary organic aerosols (SOA) in the Lower Fraser Valley (LFV) of British Columbia. The predicted concentrations of SOA show reasonable accord with ambient aerosol measurements and indicate considerable seasonal variability in SOA potential. Particulate carbon contributes only approx. 3% of total carbon concentrations in the LFV, and it is shown that variability in total carbon concentrations is significantly larger than variability in gas/particle partitioning.

Aerosols↗
PubMed1999

Assessment of pollution aerosols sources above the Straits of Dover using lead isotope geochemistry.

We assess the capability of lead isotopes to study the transport of pollution aerosols above the Straits of Dover by collecting atmospheric aerosols above the Eastern Channel and the Southern Bight of the North Sea. During the same period, we characterized the lead isotopic signature of the main industrial sources on the French coast near the Straits of Dover. Urban and automobile-derived aerosols were also collected. Due to the phasing out of lead in gasoline, the urban isotopic composition (206Pb/207Pb = 1.158 +/- 0.003) has become more radiogenic, although it is highly variable. On a regional scale, major industrial emissions have a well-defined isotopic composition (1.13 < 206Pb/207Pb < 1.22), more radiogenic than the petrol-lead signature (1.06 < 206Pb/207Pb < 1.12). These results together with those measured near the main coastal highway show that the automobile source has become a minor component of particulate lead in air. On a local scale, Dunkerque, the most urbanized and industrialized area along the Straits of Dover, may transiently control elevated lead concentrations. Except for the occurrence of local and regional range transport episodes, lead concentrations in the Straits of Dover can be related to remote or semi-remote pollution source emissions. Combining air mass retrospective trajectories and related lead abundances and isotopic compositions, it can be shown that lead aerosols originating from eastern Europe have an isotopic signature (1.145 < 206Pb/207Pb < 1.169) different from the isotopic composition of west-European lead aerosols (1.111 < 206Pb/207Pb < 1.142). The influence of remote North American sources is suggested, with caution, due to uncertainties in meteorological calculations.

Aerosols↗
PubMed1999

Pigs aerogenously immunized with genetically inactivated (ghosts) or irradiated Actinobacillus pleuropneumoniae are protected against a homologous aerosol challenge despite differing in pulmonary cellular and antibody responses.

Aerosol immunization is a safe way to induce complete protection against pleuropneumonia in pigs caused by the lung pathogenic bacterium Actinobacillus pleuropneumoniae. In order to determine the local immune responses of vaccinees in concomitant with protection, lung lining fluid before and 3 weeks after immunization from pigs immunized three times with aerosols of either genetically inactivated ghosts which represent whole cell envelope preparations, or irradiated bacteria were examined following an homologous aerosol challenge. Specific antibody isotypes in the bronchoalveolar lavage were assayed by whole cell ELISAs. Total and relative numbers of cells including lymphocyte subsets were determined. In both vaccinated groups a net influx of plasma cells and lymphocytes, as well as a significant increase of specific IgG occurred. Concurrently, the CD4+/CD8+ ratio was found to increase after aerosol immunization. The lymphocyte subsets of IgG+ and IgA+ cells were found significantly higher in the group immunized with irradiated bacteria when compared to pigs immunized with bacterial ghosts. The latter group showed a significant increase of IgA, IgM, and a net influx of lymphoid blasts and granulocytes in the bronchoalveolar lining fluid. Although differences between the local immune responses of both immunized groups occurred, a significant increase of specific IgG and a net influx of plasma cells and lymphocytes were found to be associated with complete protection against a homologous aerosol challenge infection.

Actinobacillus Infections↗
PubMed1992

Aerosol penetration through surgical masks.

BACKGROUND: Surgical masks are used in hospitals to reduce postoperative infection in patients. The presence of aerosols containing pathogens makes it desirable to protect the medical staff as well. METHODS: The collection efficiencies of surgical masks measured with two aerosol-size spectrometers. The flow rates through the masks were varied from 5 to 100 L/min to study the flow dependency. For comparison, several industrial-type respirators were also tested. RESULTS: A surgical mask consisting of filter material performed better than did a surgical mask consisting only of a shell with a coarse pore structure. The latter passed 80% of submicrometer-sized aerosols with little flow dependency, whereas the penetration of submicrometer-sized aerosols through the mask made of filter material ranged from 25% at a flow rate of 5 L/min to 70% at 100 L/min. CONCLUSIONS: The mask that has the highest collection efficiency is not necessarily the best mask from the perspective of the filter-quality factor, which considers not only the capture efficiency but also the air resistance. Although surgical mask media may be adequate to remove bacteria exhaled or expelled by health care workers, they may not be sufficient to remove the submicrometer-size aerosols containing pathogens to which these health care workers are potentially exposed.

Aerosols↗
PubMedDate not supplied

Use of telemetry to assess vaccine-induced protection against parenteral and aerosol infections of Venezuelan equine encephalitis virus in non-human primates.

Two investigational vaccines, TC-83 (live-attenuated) and C-84 (formalin-inactivated), are currently available to immunize at-risk individuals against Venezuelan equine encephalitis virus (VEE). Ideally, such vaccines should protect against both the natural mosquito-borne route of infection and from aerosol, the most common route of laboratory infection. Whereas considerable data on vaccine efficacy following parenteral challenge are available, the efficacy of these vaccines against disease caused by aerosol exposure is not well established in primates. We compared the immunogenicity and protective capacity of TC-83 and C-84 against either subcutaneous or aerosol routes of infection in cynomolgus monkeys implanted with temperature-monitoring radiotelemetry devices. A single s.c. dose of TC-83, or three s.c. doses (days 0, 7, 28) of C-84, elicited similar serum virus-neutralizing antibody responses. Animals immunized with either TC-83 or C-84 were protected against s.c. infection. In contrast, after aerosol infection, 40% of the animals vaccinated with either TC-83 or C-84 developed signs nearly as severe as those seen in unvaccinated animals. Protection was not entirely consistent with the measured preinfection immune responses: unprotected animals had serum virus-neutralizing antibody titers and lymphoproliferative responses similar to those seen in protected animals. In this study, C-84 (three doses) protected monkeys as well as TC-83 (one dose) against either a s.c. or aerosol VEE challenge.

Aerosols↗
PubMed1997

Vaccinator device for delivering propellant-driven aerosols of Streptococcus suis bacterin into the respiratory tracts of swine.

Metered-dose propellant-driven small particle aerosols of a killed whole bacterium, Streptococcus suis, were produced and characterized for their aerodynamic particle sizes and antigenicity as potential respiratory mucosal vaccines against S. suis infections in swine. To facilitate the efficient delivery of such vaccine aerosols to large animals, an electro-mechanical device was developed to synchronize aerosol release to an animal's inhalation cycles. The device was tested for its capacity to deliver a fluorescein conjugate of this bacterin (FITC-S. suis) into the respiratory tracts of 18 pigs. Results showed that FITC-S. suis could be detected in the lungs of swine as small as 4.5 kg with as few as two aerosol actuations. Metered-dose propellant-driven aerosols of bacterin vaccines delivered by this respiratory vaccinating device are discussed as a new approach for stimulated mucosal immunity against respiratory infections in animals.

Aerosol Propellants↗
PubMedDate not supplied

The deposition of hygroscopic phosphoric acid aerosols in ciliated airways of man.

The hygroscopic growth of phosphoric acid aerosol (Dc greater than 0.5 micron) within the human tracheobronchial tree is modeled to investigate changes in deposition characteristics when compared to nonhygroscopic aerosols of identical preinspired size. Phosphoric acid particles are assumed to grow in a stepwise fashion to 99% relative humidity (RH) within conducting airways of the lung, having initially reached equilibrium at 90% RH (T = 37 degrees C) in the trachea. Deposition efficiencies for growth and no growth are calculated from theoretical equations for inertial impaction, sedimentation and diffusion. The results show that neglecting the growth of an inhaled phosphoric acid aerosol may result in underestimation of the total deliverable dose by a factor of as much as 600-700%. Significant differences in regional deposition sites for hygroscopic or nonhygroscopic aerosols are predicted. Increased deposition efficiencies imply that measured physical properties (respirable fraction, aerodynamic diameter) of aerosols alone are not sufficient to assess deposition characteristics within the lung; hygroscopic growth must also be considered.

Aerosols↗
PubMed2003

A study on major inorganic ion composition of atmospheric aerosols at Tirupati.

Atmospheric aerosol samples were collected from an urbanized area (Tirupati, South India) during the period April to September 2001 and were analyzed for major inorganic ions-F, Cl, NO(3,) SO(4), Na, K, Mg, Ca and NH(4) by employing the ion chromatograph. The average mass of the aerosol was found to be 55.64 microgram(-3) with a total water-soluble load (total anion+total cation) of 5.74 microgram(-3). Seasonal distribution of the aerosol mass and temporal variations of the ion concentrations present a clear trend of lowering atmospheric levels during the rainy season due to washout effect. Composition of the aerosols showed higher concentration of SO(4) followed by NO(3) and NH(4) and found to be influenced by local terrestrial sources. The presence of SO(4) and NO(3) may be due to re-suspension of soil particles (formation by heterogeneous oxidation). Ca, Mg and Cl are mainly soil derived ones. The presence of NH(4) may be attributed to the reaction of NH(3) vapors with acidic gases such as H(2)SO(4), HNO(3) and HCl or ammonia vapor may react or condense on an acidic particle surface of anthropogenic origin. Equivalent ratios of NH(4)/(NO(3)+SO(4)) varied between 0.62 and 0.74. It shows the aerosol to be slightly acidic due to the neutralization of basicity by SO(2) and NO(x).

Aerosols↗
PubMed2003

A system for the production and delivery of monodisperse salbutamol aerosols to the lungs.

An aerosol system is described for the generation and delivery of measured doses of monodisperse therapeutic drug particles to the human lungs. The system comprises a spinning top aerosol generator (STAG), aerosol chamber and inhalation control unit. Monodisperse aerosols allow drug particle size effects to be studied as the dose is within a narrow size distribution and when combined with controlled inhalation may lead to more precise targeting of therapeutic drug to the airways. Using the STAG, particles in the size range 1.5-12 microm were generated and their mass median aerodynamic diameter (MMAD) and concentration measured using an aerodynamic particle sizer (APS). The application and validation of the system with the bronchodilator drug salbutamol sulphate is described, and its potential use in the study of aerosol particle size effects is discussed.

Administration, Inhalation↗
PubMed1999

Stabilization of aerosolized IFN-gamma by liposomes.

Aerosolized IFN-gamma is very unstable. We have improved the stability of IFN-gamma in the jet nebulizer by adding small liposomes. Aerosolized IFN-gamma was recovered in PBS solution by bubbling and its concentration was determined. After nebulization for 30 min, aerosolized IFN-gamma was detected only 0.4+/-0.2% of the initial amount in the PBS solution and 3.1+/-0.7% in the reservoir. On the other hand, the addition of small liposomes (HSPC/DSPG=10/1 (molar ratio), 45+/-24 nm) in the nebulizer increased the stability of IFN-gamma, 27.2+/-4.7% of the initial amount in the PBS solution and 25.7+/-12.6% in the reservoir. The present study also examined the effects of composition and concentration of liposomes on the stabilization of aerosolized IFN-gamma. Liposome prepared from distearoyl phosphatidylcholine (DSPC) or hydrogenated soy phosphatidylcholine (HSPC) was very effective for stabilization of aerosolized IFN-gamma (DSPC/DPPG=10/1, HSPC/DSPG=10/1). HSPC/DSPG liposome was efficient at the concentration higher than 12.5 micromols/ml for the stabilization of 5x10(5) JRU/ml of IFN-gamma. In considering the mechanism of this stabilization, the results of gel filtration chromatography suggest that IFN-gamma is inactivated by polymerization or aggregation in nebulization, while the inactivation is suppressed by liposomes due to their adsorption to IFN-gamma.

Aerosols↗
PubMed1998

[Is the use of ribavirin aerosols in respiratory syncytial virus infections justified? Clinical and economic evaluation].

UNLABELLED: The controversy about the use of ribavirin aerosol for children at risk (cardiopathy, pneumopathy, premature and immunodeficient patients), in case of respiratory syncytial virus (RSV) infection, led us to stop its prescription in 1993 and study prospectively the patients admitted during the following winters. METHODS: Criterias of inclusion for this study were those of the Committee on Infectious Diseases of the American Academy of Pediatrics concerning the use of ribavirin aerosol. Two cohorts of patients were studied: the first group included treated patients (ribavirin group: n = 22, ribavirin and support treatment: salbutamol aerosols, respiratory physiotherapy and oxygen-therapy; winters 1989-1990 to 1992-1993); the second group included patients with support treatment only (control group: n = 22; winters 1993-1994 and 1994-1995). RESULTS: The clinical gravity score at admission (4.55 vs 5.23, P = 0.46) and the risk factor scores (3.05 vs 3.27, P = 0.69) of the two groups were identical. Results showed that the children of the ribavirin group stayed much longer in hospital (14.2 vs 8.2 days, P = 0.002) and in the intensive care unit (7.2 vs 0.2 days, P < 0.001) than those of the control group. More support treatment was necessary for the ribavirin group as regard respiratory physiotherapy (3.8 vs 2.7 sessions a day, P = 0.026), the duration of oxygen-therapy (7.3 vs 3.7 days, P = 0.030) and the number of children requiring respiratory assistance (4 vs 0 children, P = 0.116). Administration of ribavirin aerosols (480 US$ a dose) and the way in which such treatment was carried out meant high daily costs for the ribavirin group (1,076 vs 604 US$, P < 0.001). As hospitalization was longer for children treated with ribavirin, the global cost was therefore much higher (15,552 vs 5,156 US$, P < 0.001). CONCLUSION: The antiviral effect of ribavirin is undeniable. However ribavirin is known to be the cause of severe bronchospasms (two cases in our study) and can also cause moderate and long term bronchospasms, aggravating therefore the clinical evolution of the disease. Our experience shows that administration of ribavirin aerosols in case of RSV infection of inferior respiratory airways seems not to be justified.

Aerosols↗
PubMed2002

Particle size analysis of radioactive aerosols formed by irradiation of argon using 65 MeV quasi-monoenergetic neutrons.

The size distributions of 38Cl and 39Cl aerosols formed from the irradiation of argon gas containing di-octyl phthalate (DOP) aerosols by 65 MeV quasi-monoenergetic neutrons were measured to study the formation mechanism of radioactive aerosols in high-energy radiation fields. Both the number size distribution and the activity-weighted size distribution were measured using an electrical low-pressure impactor. It was found that the 35Cl and 39Cl aerosols are formed by attachment of the radioactive atoms generated by the neutron-induced reaction to the DOP aerosol particles.

Aerosols↗
PubMedDate not supplied

Detection of aerosolized cells during carbon dioxide laparoscopy.

Laparoscopic surgery for malignancy has been complicated by port-site recurrences. The exact mechanism has yet to be defined. In vitro studies suggest that carbon dioxide-induced tumor cell aerosolization may play a role. We have attempted to document this in a human model. Patients scheduled for elective laparoscopy underwent port placement and abdominal insufflation with carbon dioxide. A suction trap was then filled with 40 cc of normal saline solution and attached to an insufflation site on the port. The carbon dioxide effluent was directed through the saline. The specimen was concentrated, resuspended, and transferred to a slide. A Papanicolaou stain was used. Thirty-five specimens were obtained. Fifteen patients (37%) had malignant disease, which was metastatic in eight. Five patients had carcinomatosis. In two of those with carcinomatosis, staining revealed a large number of malignant cells. Malignant cells were not found in any other patients. In two patients, however, aerosolized mesothelial cells were identified. Follow-up ranged from 2 to 7 months. One patient who displayed cellular aerosolization developed a port-site recurrence. We conclude that malignant cells are aerosolized but only during laparoscopy in the presence of carcinomatosis. It is unlikely that tumor cell aerosolization contributes significantly to port-site metastasis.

Aerosols↗
PubMed2002

Interleukin-2 liposomes for primary immune deficiency using the aerosol route.

This is the first report of aerosol interleukin 2 (IL-2) liposome administration to individuals with immune deficiency. Parenteral IL-2 therapy has shown beneficial effects in some patients with cancer, common variable immunodeficiency (CVID), and human immunodeficiency virus (HIV) but is problematic because of side effects including fever and malaise as well as local swelling (delayed type hypersensitivity like reaction) after each subcutaneous IL-2 injection. Provision of an IL-2:human albumin liposome formulation via the aerosol route had few side effects in a recent clinical trial in cancer patients. Details of good manufacturing practice (GMP) synthesis and analysis of IL-2 liposomes (N= 6 lots) made without albumin carrier protein and placebo liposomes (three lots) are presented. After centrifugation, IL-2 was closely associated with the liposome pellet (99%). Mean diameter of liposomes was 1.1 microm. Patient acceptance, safety, toxicity, and immune effects of IL-2 liposomes were studied in individuals with primary immune deficiency (N = 15) and subsequently, a larger cohort of patients with hepatitis C. Experience in the immune deficient patients is the subject of this report. Placebo liposomes (12 weeks) and IL-2 liposomes (12 weeks) were provided using a nebulizer. Aerosol placebo liposomes and IL-2 liposomes were well tolerated. No changes in chest X-ray or pulmonary function were seen. Since biologic activity of aerosol IL-2 liposomes has been seen in viral disease (hepatitis C), additional studies of aerosol IL-2 liposomes in individuals with hepatitis C and HIV are planned.

Administration, Inhalation↗
PubMed1977

Mechanisms of inactivation of bacteriophage phiX174 and its DNA in aerosols by ozone and ozonized cyclohexene.

The mechanisms of inactivation of aerosolized bacteriophage phiX174 in atmospheres containing ozone, cyclohexene, or ozonized cyclohexene were studied by using 32P-labelled phage. The inactivation of the aerosolized phage in clear air or in air containing cyclohexene is due to damage of the protein coat since the deoxyribonucleic acid (DNA) extracted from the inactivated phage retains its biological activity. Inactivation of the phage in air containing ozonized cyclohexene is due both to protein and DNA damage. Sucrose gradient analysis shows that aerosolized inactivated phiX174 releases unbroken DNA. In contrast, the DNA from phage phiX174 inactivated by ozonized cyclohexene is broken. The inactivation of aerosolized phage phiX174-DNA was studied in the same atmospheres using 32P-labelled DNA. phiX174-DNA aerosolized in clear air or air containing cyclohexene at 75% r.h. is inactivated by a factor of 2 in 30 min. The inactivated DNA is broken. Ozone as well as ozonized cyclohexene inactivates KNA very fast causing breaks in the molecule. This is in contrast with the intact bacteriophage in which ozone does not produce breaks in the DNA.

Aerosols↗