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At least 721 records · Page 40Linked to original sources
PubMed1999

Microanalysis of indoor aerosols and the impact of a compact high-efficiency particulate air (HEPA) filter system.

Aerosol particles in municipal atmospheres are of increasing public health concern; however, since most of our time is spent indoors, indoor aerosols must be researched in counterpart. Compact High-Efficiency Particulate Air (HEPA) filter systems are commonly employed in residences to alleviate airborne dust concentrations. In this study, a detailed and original methodology was used to determine concentrations and types of submicrometer aerosols, as well as of large (> 4 microns) dust particles. Scanning electron microscopy was used to quantify and characterize ambient aerosols collected from filtered and non-filtered rooms. Particle concentrations were significantly lower in samples collected in the presence of the filter system (mean 23 to 8 coarse particles liter-1, 63% reduction; 13 to 3 inorganic submicron particles cm-3, 76% reduction; 85 to 33 total submicron particles cm-3, 62% reduction; all P < 0.05). This study provides a new methodology for analysis of indoor aerosols and new data on their physico-chemical characteristics. Since the filter systems are effective at reducing submicron aerosol concentrations, they may improve the health of individuals such as asthmatics, who experience health problems caused by anthropogenic fine particles.

Aerosols↗
PubMed1984

Pulmonary deposition and clearance of aerosolized interferon.

Small particle aerosols of a hybrid DNA recombinant human alpha interferon, A/D bgl, and a related DNA recombinant leukocyte interferon, A, were generated and delivered to mice for 23.5 h a day for 4 consecutive days. The antiviral activity of these interferons in delivery reservoirs, in the aerosols generated, and in the lungs of test mice was monitored during and after aerosol administration in cytopathic effect inhibition assays, using vesicular stomatitis virus as the indicator virus. In addition, the activity of these interferons in primary mouse embryo cells against influenza A/HK/68 (H3N2) virus was determined. The results obtained indicated that the interferon particles generated in the continuous aerosol therapy system used in these studies remained biologically active and could be readily detected in both aerosol mists and lungs of test mice; levels of exogenous interferon in the lungs equalled or exceeded levels of interferons produced endogenously during experimentally induced influenza virus infection. Titers of the exogenously administered interferons decreased gradually and disappeared from the lungs between 24 and 48 h after cessation of aerosolization. Recombinant human alpha interferon A/D, but not recombinant leukocyte alpha interferon A, significantly inhibited replication of A/HK/68 virus in primary mouse embryo cells in the in vitro studies.

Aerosols↗
PubMed1987

Successful treatment with aerosolized pentamidine of Pneumocystis carinii pneumonia in rats.

We examined both the therapeutic efficacy and tissue distribution of aerosolized pentamidine in immunosuppressed rats with Pneumocystis carinii pneumonia. In rats immunosuppressed by 5 weeks of pretreatment with dexamethasone, a 2-week course of 5 mg of aerosolized pentamidine per kg per day, administered free or encapsulated in the drug carrier system (liposomes), eradicated P. carinii pneumonia in 75% of treated animals. At this dose, extrapulmonary drug uptake as measured by a sensitive high-pressure liquid chromatography assay was negligible. No significant differences in tissue distribution were noted between aerosolized free and liposome-encapsulated pentamidine. In rats receiving dexamethasone for 6 weeks prior to treatment with pentamidine, both lung uptake and therapeutic efficacy of aerosolized pentamidine (5 mg/kg per day) were substantially reduced. Aerosolized pentamidine appears to be an effective therapy for P. carinii pneumonia in rats and produces significantly lower extrapulmonary drug deposition than parenteral administration. The severity of P. carinii involvement at the time of treatment influences both the level of drug delivery to the lung and the response to aerosolized pentamidine therapy.

Aerosols↗
PubMed1990

Effect of aerosolization on subsequent bacterial survival.

To determine whether aerosolization could impair bacterial survival, Pseudomonas syringae and Erwinia herbicola were aerosolized in a greenhouse, the aerosol was sampled at various distances from the site of release by using all-glass impingers, and bacterial survival was followed in the impingers for 6 h. Bacterial survival subsequent to aerosolization of P. syringae and E. herbicola was not impaired 1 m from the site of release. P. syringae aerosolized at 3 to 15 m from the site of release at a temperature of 12 degrees C and a relative humidity of 80% survived 35- to 65-fold better than P. syringae released at 27 degrees C and a relative humidity of 40%. No difference was observed in the survival of P. syringae and E. herbicola following aerosolization at the same temperature and relative humidity. Bacteria sprayed directly onto bean and oat plants established stable populations at comparable numbers on both plants over an 8-day period following inoculation. Bacteria that inoculated adjacent plants by drifting downwind up to 5 m were detectable at an initial population of 10(2) CFU/g on oats and 10(5) CFU/g on beans 2 h after the spray. However, bacterial populations on both plants were undetectable within 48 h.

Aerosols↗
PubMed1970

Homogenous bacterial aerosols produced with a spinning-disc generator.

Aerosols composed of viable particles of a uniform size were produced with a commercial spinning-disc generator from aqueous suspensions of Bacillus subtilis var. niger spores containing various amounts of an inert material, dextran, to regulate aerosol particle size. Aerosols composed of single naked spores having an equivalent spherical diameter of 0.87 mum were produced from spore suspensions without dextran, whereas aerosols produced from suspensions containing 0.001, 0.01, 0.1, and 1% dextran had median diameters of 0.90, 1.04, 1.80, and 3.62 mum, respectively. Such aerosols, both homogeneous and viable, would be useful for calibrating air sampling devices, evaluating air filter systems, or for employment wherever aerosol behavior may be size-dependent.

Aerosols↗
PubMed1971

Effect of relative humidity on dynamic aerosols of adenovirus 12.

Dynamic aerosols of adenovirus 12 were generated in the same Henderson apparatus under conditions of high, medium, and low relative humidity. High relative humidities resulted in more recovery of adenovirus 12 from aerosols and lungs of newborn Syrian hamsters. At 89, 51, and 32% relative humidity, the total infectious virus recovered from a 20-min aerosol was 10(6.7), 10(6.0), and 10(4.3) TCD(50), respectively. Hamsters exposed to these 20-min aerosols retained measured lung doses of 10(3.0), 10(2.4), and 10(1.0) TCD(50), respectively. The measured retained lung doses were compared to calculated inhaled lung doses based on both total virus aerosolized and total virus recovery from the aerosols.

Adenoviridae↗
PubMed1972

Aerosol survival of Pasteurella tularensis and the influence of relative humidity.

The aerosol survival in air was determined for Pasteurella tularensis live vaccine strain (LVS) as a function of relative humidity (RH). Three different preparations of bacteria were used: (i) liquid suspension of P. tularensis LVS in spent culture medium; (ii) powders of P. tularensis LVS freeze-dried in spent culture fluid; (iii) P. tularensis LVS freeze-dried in spent culture fluid and then reconstituted with distilled water and disseminated as a liquid suspension. Preparation (i) gave greatest survival at high RH and lowest survival at intermediate RH. Preparation (ii), in contrast, gave greatest survival at low RH and minimum survival at 81% RH. Preparation (iii) was the same as preparation (i), i.e., the process of freeze-drying and reconstituting with distilled water before aerosol formation had little or no effect upon aerosol survival as a function of RH. Hence, control of aerosol survival appears to be through the water content of P. tularensis LVS at the moment of aerosol generation rather than the water content of the bacteria in the aerosol phase.

Aerosols↗
PubMed2002

Quantitative priming with inactivated pertussis toxoid vaccine in the aerosol challenge model.

Serum antibodies to pertussis toxin (PT) have been shown to be protective against severe pertussis disease, although a specific level of anti-PT antibody that correlates with protection has not been demonstrated. Current animal models such as the intracerebral challenge model have significant limitations in correlating protection to a specific level of anti-PT antibody. This study examines the protective effects of priming with tetranitromethane-inactivated pertussis toxoid (PTx) vaccine in the aerosol challenge model and whether a measurable response to a priming dose of PTx is enough to initiate a protective secondary response when challenged with infection. The correlation of priming with markers of illness such as leukocytosis, weight loss, bacterial proliferation, and mortality after established infection with Bordetella pertussis was explored. BALB/c mice were immunized with PTx vaccine on day 6 of life and then challenged with B. pertussis using the aerosol challenge model. Data were analyzed according to the primary immunologic response, differentiating responders (anti-PT immunoglobulin G [IgG] > or =1 microg/ml) from nonresponders (anti-PT IgG <1 microg/ml). Mice that showed evidence of priming on the day of aerosol challenge were able to mount a secondary response to the challenge with a > or =2-fold rise in anti-PT IgG antibody by day 7 and a > or =10-fold rise by day 14 post-aerosol challenge. These primed mice were significantly better protected against leukocytosis, weight loss, and proliferation of B. pertussis in the lungs following aerosol challenge than the nonprimed group. This protection correlated with levels of anti-PT antibody in serum present on the day of aerosol challenge.

Aerosols↗
PubMed2004

Aerosolized gamma interferon (IFN-gamma) induces expression of the genes encoding the IFN-gamma-inducible 10-kilodalton protein but not inducible nitric oxide synthase in the lung during tuberculosis.

Gamma interferon (IFN-gamma) is critical in the immune response against Mycobacterium tuberculosis. In an ongoing trial of aerosol IFN-gamma in conjunction with standard drug therapy, we have observed activation of IFN signaling in bronchoalveolar lavage (BAL) cells from tuberculosis (TB) patients. We hypothesized that aerosol IFN-gamma treatment of pulmonary TB would increase expression of genes important for the control of TB. We investigated the expression of downstream genes by measuring inducible nitric oxide synthase (iNOS) and the chemokine IFN-inducible 10-kDa protein (IP-10) by real-time quantitative reverse transcription-PCR. In vitro, M. tuberculosis induced IP-10, and IFN-gamma stimulated this further, with no effect on iNOS expression. We studied 21 patients with pulmonary TB and 7 healthy subjects. Similar to the in vitro model, IP-10 mRNA was increased in BAL cells from TB patients and was augmented after treatment with aerosolized IFN-gamma. TB was also associated with elevated iNOS mRNA, but aerosolized IFN-gamma did not further enhance expression. Genomic analysis identified 1,300 of 4,058 genes expressed in BAL cells from six TB patients before and after 1 month of therapy, including aerosolized IFN-gamma. However, only 15 genes were differentially regulated by IFN-gamma. We conclude that iNOS and IP-10 mRNA expression is increased in TB but that aerosol IFN-gamma treatment increases expression of few genes in the human lung.

Adult↗
PubMed1977

Evaluation of a simple device for bacteriological sampling of respirator-generated aerosols.

The Aerotest sampler (Olympic Medical Corp., Seattle, Wash.) is designed to detect bacterial contamination of respirator-generated aerosols in a simple one-step process. The sampler was evaluated by controlled contamination of Bennett AP-5, PR-2, and MA-1 respirators with Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter. Bacteria present as viable 1.4 to 3.5-mum particles in each of 77 aerosols were quantitated by using the Andersen viable-particle sampler, and the results were compared with those of colonies obtained from 10-s or 15-cycle Aerotest samples. All aerosols containing counts greater than expected in hospital air were detected by the Aerotest method. Thirteen of 14 aerosols containing less than 20 bacteria/0.028 m3 showed fewer than 5 colonies, whereas all aerosols containing greater than 1,000 bacteria/0.028 m3 showed at least 40 colonies. Aerosols with intermediate counts fell in between. Under the conditions described here, the Aerotest sampler was able to discriminate between the low levels of bacteria commonly found in hospital air and the bacterial contamination associated with nosocomial pneumonia. The Aerotest sampler provides a practical method for surveillance sampling of respirator nebulizers.

Acinetobacter↗
PubMed1993

Pulmonary deposition of a nebulised aerosol during mechanical ventilation.

BACKGROUND: There is increasing use of therapeutic aerosols in patients undergoing mechanical ventilation. Few studies have measured aerosol delivery to the lungs under these conditions with adequate experimental methods. Hence this study was performed to measure pulmonary aerosol deposition and to determine the reproducibility of the method of measurement during mechanical ventilation. METHODS: Nine male patients were studied during mechanical ventilation after open heart surgery and two experiments were performed in each to determine the reproducibility of the method. A solution of technetium-99m labelled human serum albumin (99mTc HSA (50 micrograms); activity in experiment 1, 74 MBq; in experiment 2, 185 MBq) in 3 ml saline was administered with a Siemens Servo 945 nebuliser system (high setting) and a System 22 Acorn nebuliser unit. Pulmonary deposition was quantified by means of a gamma camera and corrections derived from lung phantom studies. RESULTS: Pulmonary aerosol deposition was completed in 22 (SD 4) minutes. Total pulmonary deposition (% nebuliser dose (SD)) was 2.2 (0.8)% with 1.5% and 0.7% depositing in the right and left lungs respectively; 0.9% of the nebuliser activity was detected in the endotracheal tube or trachea and 51% was retained within the nebuliser unit. Considerable variability between subjects was found for total deposition (coefficient of variation (CV) 46%), but within subject reproducibility was good (CV 15%). CONCLUSIONS: Administration of aerosol in this way is inefficient and further research is needed to find more effective alternatives in patients who require mechanical respiratory support. This method of measurement seems suitable for the assessment of new methods of aerosol delivery in these patients.

Administration, Inhalation↗
PubMed1995

An alternative aerosol delivery system for amiloride.

BACKGROUND: The advent of novel treatments such as aerosolized amiloride are potentially useful additions to the therapeutic options available for the treatment of cystic fibrosis. Unfortunately, amiloride and other aerosolized drugs such as antibiotics are generally administered via jet nebulisers which are time consuming to use, and thus limit the acceptance and efficacy of these forms of treatment. In vitro experiments were performed in order to determine whether amiloride could be administered in dry powder form using a Turbohaler. METHODS: Amiloride was micronised and loaded into 200 micrograms Turbohalers. The dose delivered per actuation and particle size distribution of the generated aerosol were assessed using a flow of 60 l/min through the Turbohaler. The dose of amiloride delivered was measured by collecting the aerosol on a filter and the quantity of drug was assayed by an ultraviolet spectrophotometric method. The particle size distribution was assessed using a Malvern MasterSizer laser particle sizer and compared with that generated by a commercially available 200 micrograms budesonide Turbohaler. RESULTS: The mean (SD) dose delivered per actuation was 246.3 (40.4) micrograms. The volume median diameter of the amiloride aerosol was 3.80 (0.68) micron compared with 3.07 (1.47) microns for budesonide. CONCLUSIONS: These results suggest that therapeutic doses of micronised amiloride could be delivered effectively and conveniently as a dry powder aerosol using a Turbohaler.

Aerosols↗
PubMed2002

Bioengineering of therapeutic aerosols.

The new field of therapeutic aerosol bioengineering (TAB), driven primarily by the medical need for inhaled insulin, is now expanding to address medical needs ranging from respiratory to systemic diseases, including asthma, growth deficiency, and pain. Bioengineering of therapeutic aerosols involves a level of aerosol particle design absent in traditional therapeutic aerosols, which are created by conventionally spraying a liquid solution or suspension of drug or milling and mixing a dry drug form into respirable particles. Bioengineered particles may be created in liquid form from devices specially designed to create an unusually fine size distribution, possibly with special purity properties, or solid particles that possess a mixture of drug and excipient, with designed shape, size, porosity, and drug release characteristics. Such aerosols have enabled several high-visibility clinical programs of inhaled insulin, as well as earlier-stage programs involving inhaled morphine, growth hormone, beta-interferon, alpha-1-antitrypsin, and several asthma drugs. The design of these aerosols, limited by partial knowledge of the lungs' physiological environment, and driven largely at this stage by market forces, relies on a mixture of new and old science, pharmaceutical science intuition, and a degree of biological-impact empiricism that speaks to the importance of an increased level of academic involvement.

Administration, Inhalation↗
PubMed1984

Tc-99m-DTPA aerosol and radioactive gases compared as adjuncts to perfusion scintigraphy in patients with suspected pulmonary embolism.

To evaluate the clinical utility of improved methods for radioaerosol inhalation imaging, we obtained preperfusion radioaerosol images in 107 patients (mean age = 62 years), who were referred for evaluation of suspected pulmonary embolism (PE). For each patient, we compared six-view aerosol images with accompanying perfusion scans and chest radiographs and with Xenon-133 (Xe-133) or Krypton-81m (Kr-81m) studies. Four observers at four different institutions independently evaluated aerosol-perfusion and gas-perfusion pairs, classifying the probability of PE as low, high, or indeterminate. The radioaerosol images were good to excellent in quality; excessive central deposition of activity was infrequent and did not interfere with image interpretation. The aerosol-perfusion studies showed 86% agreement with Xe-133 perfusion interpretations (n = 299) and 80% agreement with Kr-81m perfusion interpretations (n = 99). These rates of agreement were comparable with those of intraobserver agreement for gas-to-gas and aerosol-to-aerosol comparisons, and higher than interobserver agreement rates. In a limited number (n = 9) of angiographically documented cases, aerosol-perfusion and gas-perfusion studies provided accurate and equivalent diagnoses. The results suggest that radioaerosol inhalation studies, performed with improved nebulizers, are diagnostically equivalent to ventilation imaging as an adjunct to perfusion scintigraphy in evaluating patients with suspected PE.

Adult↗
PubMed1984

Effects of granulocyte depletion on pulmonary responsiveness to aerosol histamine.

The effects of granulocyte depletion with hydroxyurea on pulmonary responsiveness to aerosol histamine were studied in 10 chronically instrumented unanesthetized sheep. Sheep were studied when granulocyte counts were normal (B), after 3 days of hydroxyurea but before granulocyte counts had dropped below 700 cells/mm3 (H), and after granulocyte counts had fallen below 200 cells/mm3 (D). Hydroxyurea itself had no effect on aerosol histamine responsiveness and the results were unaffected by the order of experimentation. All 10 sheep were less responsive (P less than 0.05) to aerosol histamine when granulocyte depleted effective dose of histamine that caused a reduction to 65% of control dynamic compliance (ED65Cdyn = 23.98 +/- 4.70 mg/ml) compared with base line (ED65Cdyn = 7.06 +/- 1.86 mg/ml). Those sheep initially most responsive to aerosol histamine had the greatest attenuation in their airway responsiveness to aerosol histamine (P less than 0.05). There was a significant negative correlation between absolute granulocyte counts in peripheral blood and pulmonary responsiveness to aerosol histamine during base-line (B) condition (r = -0.74, P less than 0.05) and for the data as a whole [r = -0.69, P less than 0.05 (B + H + D)]. Circulating granulocytes and/or pulmonary inflammation may contribute to pulmonary responsiveness to bronchial challenge.

Aerosols↗
PubMed1985

Aerosol deposition in the airway model with excessive mucus secretions.

Aerosol deposition in the airways with excessive mucus secretions was investigated utilizing an in vitro airway model lined with various mucus simulants of differing rheological properties. The airway model was made with a straight glass tube (1.0 cm ID and 20 cm in length) and positioned vertically. The mucus simulants were supplied into the tube at a constant rate and made to move upward through the tube as a thin layer (0.6-1.7 mm) undergoing a random wave motion by means of upward airflow. Aerosols (3.0 and 5.0-micron diam) were passed through the mucus-lined tube at flow rates of 0.33-1.17 l/s, and the deposition of the aerosols in the tube was determined by sampling the aerosols at the inlet and the outlet of the tube on filters. During the sampling, pressure drop across the tube model was also measured. Deposition efficiency in the 20-cm-long mucus-lined tube ranged from 13 to 92% with 3.0-micron-diam particles and from 66 to 98% with 5.0-micron-diam particles. This deposition was 25-300 times higher than that in the dry tube. The deposition was higher with increasing viscosity of mucus but was lower with increasing elasticity of mucus. Pressure drop across the mucus-lined tube was much higher than that in the dry tube, and the increase was more prominent with mucous layers with higher viscosity but lower elasticity values. Therefore, aerosol deposition showed a good positive relationship with pressure drop. However, percent increase of aerosol deposition in the mucus-lined tube was 2-5 times higher than that of pressure drop.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1994

Aerosolized deferoxamine prevents lung and systemic injury caused by smoke inhalation.

We assessed the role of oxidant release at the airway mucosal surface on airway injury and systemic response to a severe smoke insult. Adult sheep (n = 20) were insufflated with well-characterized smoke from burning cotton toweling. A standardized dose of 12 breaths of smoke with a tidal volume of 20 ml/kg was given under anesthesia. Sheep were awakened, monitored for 24 h, and killed; data were compared with control sheep. Sheep were given 1) humidified oxygen, 2) continuous aerosol of 10% deferoxamine (DFO)-pentastarch solution beginning after smoke, 3) DFO-alone aerosol, or 4) pentastarch-alone aerosol. DFO has antioxidant properties directly and chelates iron. Severe respiratory failure occurred in all but DFO-pentastarch group. Shunt fraction increased from a control of 4%. Histological assessment revealed severe airway mucosal edema, ulceration, bronchorrhea, and severe atelectasis but only moderate alveolar edema. Increased lipid peroxides were also noted in free airway fluid and in bronchoalveolar lavage fluid. In addition, oxygen consumption increased by 75%, fluid requirements increased threefold, and protein-rich systemic soft tissue lymph flow doubled, all significant increases compared with control sheep. No significant physiological or histological changes were noted in DFO-pentastarch aerosol group. We conclude that 1) oxidants possibly initiated through free iron release are involved in severe smoke-induced airway injury and resulting systemic inflammatory response, probably through an amplified oxidant injury and 2) an aerosol of a DFO-pentastarch complex prevents the injury process, whereas DFO alone is not effective as an aerosol.

Acute Disease↗
PubMed1994

One-dimensional simulation of aerosol transport and deposition in the human lung.

One-dimensional transport models (trumpet model and multibranch-point model) derived from those developed to study gas transport and mixing in the lung are used to simulate aerosol deposition as a function of particle diameter and aerosol dispersion of inhaled bolus in human lungs. In agreement with previous studies, aerosol deposition is satisfactorily simulated by the different models. However, the differences between simulations and experiments of aerosol bolus dispersion suggest that current models are not realistic. This is probably due to the intrinsic limitations of the one-dimensional models to describe aerosol transport in the lung periphery. We show that future model analyses can probably use a symmetric acinar structure like the classic Weibel model of the lung but that multidimensional particle transport equations are required. Furthermore, a rigorous description of aerosol dispersion in the oral-laryngeal path is also needed.

Aerosols↗