Simultaneous Inhalation Research Articles

Associations between inhalation of typical volatile and semi-volatile organic compounds in e-waste dismantling workers with liver function damage

Studies in cell culture and animal models suggest hepatotoxicity of some volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), however, their effects in human populations under real exposure conditions have never been clarified. In this cross-sectional study, 224 participants, 38 e-waste dismantling workers and 186 subjects residing near to the dismantling sites in southern China, were evaluated for personal inhalational exposure to 72 VOCs and 91 SVOCs according to site-specific atmospheric chemical concentrations and personal exposure time. Additionally, their serum samples were subjected to liver function tests (LFTs), including total protein (TP), albumin (ALB), globulin (GLB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and bilirubin. Linear regression analysis of the VOC/SVOC levels against the LFTs results indicated that VOC exposure was negatively associated with the TP, ALB, GLB levels (indicating liver-specific protein synthesis functions), while positively associated with AST, ALT, GGT activities (marking liver damage). Somehow, SVOC exposure appeared to be positively associated with not only AST and ALT but also TP and ALB. These findings were supported by the quantile g-computation analysis and confirmed in the Bayesian kernel machine regression model. This study indicates that simultaneous inhalation of VOCs and SVOCs may impair human liver functions.

Compatibility and aerosol characteristics of beclomethasone mixed with N-acetylcysteine

Mixing different kind inhalation medications for simultaneous inhalation is widely used in the treatment of chronic respiratory diseases, and it can minimize the administration time and improve patient adherence. To our knowledge, it is unclear whether beclomethasone (BDP, Clenil®) can bemixed with acetylcysteine (NAC, Fluimucil®), because the in vitro physico-chemical compatibility and aerosol characteristics of the mixture are unknown. In this study, we investigated physical compatibility, including the appearance, pH, osmotic pressure and chemical stability, as well as aerosol characteristics, including particle size corresponding to 10%/50%/90% of the cumulative percentage of total particle volume (X10/X50/X90), volume median droplet diameter (VMD), mass median aerodynamic diameter (MMAD), fine particle fraction (FPF), fine particle dose (FPD) and geometric standard deviation (GSD), delivery rate, and total delivery of the above solutions. After mixing, there were no significant changes in visual appearance, pH, osmolality and drug content of the mixtures at room temperature for 12 h. The FDP of BDP in the mixture decreased by 16.49%, whereas the NAC increased by 10.85%. The delivery rates of BDP and NAC in the mixture decreased by 66.05% and 45.54%, and total delivery increased by 13.20% and 25.29%, respectively. However, the MMAD, FPF, particle size and GSD of the mixture were almost unchanged. We demonstrated that these admixtures are physico-chemically compatible but that coadministration of beclomethasone with acetylcysteine can markedly affect output and aerosol characteristics.

Hyperbaric oxygen therapy : Selected indications in the discipline of otorhinolaryngology

Hyperbaric oxygenation (HBO) represents the controlled exposure to positive pressure with simultaneous inhalation of pure oxygen. It is considered to be an effective treatment option for diseases with restricted blood flow as oxygen not only binds chemically to hemoglobin but also physically dissolves in blood plasma. With the help of ahyperbaric chamber the ambient pressure of apatient can be modified and the physiological characteristics in positive pressure can be medically used. The indications relevant to otorhinolaryngology are necrotizing otitis externa and skull base osteomyelitis, other forms of osteomyelitis, gangrene, wound healing disorders and sudden loss of hearing. When choosing atreatment, not only the availability and costs of HBO treatment play arole but also the patient's tolerance of overpressure. The risks of treatment, e.g., due to oxygen toxicity or barotrauma of the middle ear or the paranasal sinuses, must be weighed up against the potential benefits.

Association between Air Pollution and Squamous Cell Lung Cancer in South-Eastern Poland.

Air pollution is closely associated with the development of respiratory illness. The aim of the present study was to assess the relationship between long-term exposure to PM2.5, PM10, NO2, and SO2 pollution and the incidence of lung cancer in the squamous subtype in south-eastern Poland from the years 2004 to 2014. We collected data of 4237 patients with squamous cell lung cancer and the level of selected pollutants. To investigate the relationship between the level of concentrations of pollutants and the place of residence of patients with lung cancer in the squamous subtype, proprietary pollution maps were applied to the places of residence of patients. To analyze the data, the risk ratio was used as well as a number of statistical methods, i.e., the pollution model, inverse distance weighted interpolation, PCA, and ordered response model. Cancer in women and in men seems to depend in particular on the simultaneous inhalation of NO2 and PM10 (variable NO2PM10) and of NO2 and SO2 (variable NO2 SO2), respectively. Nitrogen dioxide exercises a synergistic leading effect, which once composed with the other elements it becomes more persistent in explaining higher odds in the appearance of cancers and could constitute the main cause of squamous cancer.

Compatible Stability and Aerosol Characteristics of Atrovent® (Ipratropium Bromide) Mixed with Salbutamol Sulfate, Terbutaline Sulfate, Budesonide, and Acetylcysteine.

(1) Background: It is common practice in the treatment of respiratory diseases to mix different inhalation solutions for simultaneous inhalation. At present, a small number of studies have been published that evaluate the physicochemical compatibility and aerosol characteristics of different inhalation medications. However, none of them studied Atrovent®. Our work aims to address the lack of studies on Atrovent®. (2) Methods: Portions of admixtures were withdrawn at certain time intervals after mixing and were tested by pH determination, osmolarity measurement, and high-performance liquid chromatography (HPLC) assay of each active ingredient as measures of physicochemical compatibility. The geometrical and aerosol particle size distribution, active drug delivery rate, and total active drug delivered were measured to characterize aerosol behaviors. (3) Results: During the testing time, no significant variation was found in the pH value, the osmotic pressure, or the active components of admixtures. With the increase in nebulization volume after mixing, fine particle dose (FPD) and total active drug delivered showed statistically significant improvements, while the active drug delivery rate decreased compared to the single-drug preparations. (4) Conclusions: These results endorse the physicochemical compatibility of Atrovent® over 1 h when mixed with other inhalation medications. Considering aerosol characteristics, simultaneous inhalation is more efficient.

Aerosol Characteristics and Physico-Chemical Compatibility of Combivent® (Containing Salbutamol and Ipratropium Bromide) Mixed with Three Other Inhalants: Budesonide, Beclomethasone or N-Acetylcysteine.

Inhalation therapy with a nebulizer is widely used in chronic respiratory disease. Mixing inhalation solutions/suspensions for simultaneous inhalation is more convenient and might simplify the administration procedure. However, there are no data available to address the in vitro aerosol characteristics and physico-chemical compatibility of Combivent® (containing Salbutamol and Ipratropium bromide) with other inhalation solutions/suspensions. In order to investigate the in vitro aerosol characteristics and physico-chemical compatibility of Combivent® with Budesonide, Beclomethasone, and N-acetylcysteine, the appearance, pH, osmotic pressure, chemical stability, mass median aerodynamic diameter (MMAD), fine particles fraction (FPF), particle size corresponding to X50 (particle size, which accounts for 50% of the total cumulative percentage of volume of all particles), delivery rate, and total delivery of the mixed inhalation solution/suspension were tested. There was no change in the appearance such as a change in color or precipitation formation at room temperature. The pH, osmolality, and chemicals of the mixtures were stable for 24 h after mixing. There were no significant differences between Combivent®, Budesonide, Beclomethasone, N-acetylcysteine, and the mixtures in MMAD, FPF, X50, the delivery rate, and the total delivery. This indicates that the mixtures were physically and chemically compatible. The mixing did not influence the particle size, distribution, or delivery compatibility of the mixtures.

The single-breath diffusing capacity of CO and NO in healthy children of European descent.

RationaleThe diffusing capacity (DL) of the lung can be divided into two components: the diffusing capacity of the alveolar membrane (Dm) and the pulmonary capillary volume (Vc). DL is traditionally measured using a single-breath method, involving inhalation of carbon monoxide, and a breath hold of 8–10 seconds (DL,CO). This method does not easily allow calculation of Dm and Vc. An alternative single-breath method (DL,CO,NO), involving simultaneous inhalation of carbon monoxide and nitric oxide, and traditionally a shorter breath hold, allows calculation of Dm and Vc and the DL,NO/DL,CO ratio in a single respiratory maneuver. The clinical utility of Dm, Vc, and DL,NO/DL,CO in the pediatric age range is currently unknown but also restricted by lack of reference values.ObjectivesThe aim of this study was to establish reference ranges for the outcomes of DL,CO,NO with a 5 second breath hold, including the calculated outcomes Dm, Vc, and the DL,NO/DL,CO ratio, as well as to establish reference values for the outcomes of the traditional DL,CO method, with a 10 second breath hold in children.MethodsDL,CO,NO and DL,CO were measured in healthy children, of European descent, aged 5–17 years using a Jaeger Masterscreen PFT. The data were analyzed using the Generalized Additive Models for Location Scale and Shape (GAMLSS) statistical method.Measurements and Main ResultsA total of 326 children were eligible for diffusing capacity measurements, resulting in 312 measurements of DL,CO,NO and 297 of DL,CO, respectively. Reference equations were established for the outcomes of DL,CO,NO and DL,CO, including the calculated values: Vc, Dm, and the DL,NO/DL,CO ratio.ConclusionThese reference values are based on the largest sample of children to date and may provide a basis for future studies of their clinical utility in differentiating between alterations in the pulmonary circulation and changes in the alveolar membrane in pediatric patients.

Effects of acute and chronic inhalation of paint thinner in mice: behavioral and immunohistochemical study

Abuse of volatile inhalants has become a worldwide issue mainly among adolescents of low income social class. Acute and chronic exposure to these substances results in serious neurological and behavioral impairments. Although real exposure consists largely of simultaneous inhalation of multiple solvents, the vast majority of basic research studies have evaluated the actions of a single volatile component leaving the behavioral and neuronal effects of chemical mixture not fully understood. In this study, we investigated the acute behavioral effects of 300, 450 and 600ppm of paint thinner inhalation on anxiety, locomotor activity and spatial memory. Additionally, the cognitive impairments related to chronic exposure of the same concentrations of thinner for 45days were assessed. To understand the neuronal correlates of acute exposure to thinner, we used c-Fos immunohistochemistry as an endogenous marker of neuronal activation following 600ppm of thinner. The results reveal that (i) chronically thinner exposed mice showed cognitive deficits in Morris water maze and object recognition tasks; (ii) acute inhalation of thinner induces a wide range of behavioral changes. These changes include an anxiolytic effect toward the aversive environmental bright light and a dose dependent effect on explorative locomotion. The wide range of behavioral alterations induced by acute thinner inhalation is consistent with the widespread distribution of thinner-induced c-Fos expression in multiple brain structures.

Inhalation solutions — Which ones may be mixed? Physico-chemical compatibility of drug solutions in nebulizers — Update 2013

Many patients suffering from chronic respiratory diseases rely on inhalation therapy with nebulizers. About 25% of patients who need to inhale several different drugs per day save time by mixing them for simultaneous inhalation. This review presents a comprehensive overview of the available data concerning physico-chemical compatibility of commonly mixed nebulizer solutions and suspensions. Information is based on our in vitro studies and a thorough literature search. Results indicate that many nebulizer solutions/suspensions are mixable without provoking incompatibilities. However, certain excipients contained in some of the tested drug products could be identified as a reason for incompatibilities, e.g. impaired activity of dornase alfa. Studies assessing the aerosol characteristics of compatible mixtures nebulized with commonly used nebulizers are limited and should be encouraged. The clinical efficacy of simultaneous inhalation of duplicate, tripartite or quadripartite mixtures must be evaluated in clinical studies before final recommendations for the inhalation regimens can be made.

Physicochemical compatibility and stability of nebulizable drug admixtures containing dornase alfa and tobramycin

The objective of this in-vitro study was to determine whether admixtures of the inhalation solutions Pulmozyme® (Dornase alfa) and either Bramitob® or Tobi® (both containing Tobramycin) are physicochemically compatible and to analyze the aerodynamic parameters of these admixtures. After mixing, test solutions were stored at room temperature and under ambient light conditions over a period of 24 h. Tobramycin concentrations were determined by using a fluorescence immunoassay. Stability of dornase alfa was determined by size-exclusion high performance liquid chromatography, ultraviolet spectroscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis and tentacle strong cation-exchange chromatography. In addition, pH values and osmolality of the admixtures were measured and test solutions were visually examined for any changes up to 24 h. Aerosols of Pulmozyme®/Bramitob® or Pulmozyme®/TOBI® admixtures were generated with the PARI eFlow® rapid and aerodynamic particle sizing was performed via cascade impaction with the Next Generation Pharmaceutical Impactor. The stability tests revealed that neither the stability of tobramycin nor the stability of dornase alfa was affected by mixing the inhalation products. Cascade impaction showed no relevant changes in particle size distribution, Mass Median Aerodynamic Diameter, Geometric Standard Deviation and Fine Particle Fraction in comparison to aerodynamic parameters of the unmixed solutions. Thus, admixtures of Pulmozyme® and either Bramitob® or TOBI® can be designated as compatible for a 24 h period and simultaneous inhalation is feasible.

Physicochemical compatibility of nebuliser solution admixtures containing colistimethate and hypertonic saline or colistimethate, fluticasone-17-propionate, ipratropium bromide and salbutamol sulfate

ObjectivesFor practical reasons, patients with cystic fibrosis (CF) tend to mix different inhalation solutions for concomitant inhalation instead of inhaling the different medications consecutively. A study was undertaken to examine...

Effects of nitric oxide and hydrogen on isolated heart and cultured myoblast cells under the condition simulating ischemia–reperfusion

Background and Aim Our recent studies have shown that simultaneous inhalation of nitric oxide (NO) and hydrogen (H2) has strong protective effects against cardiac ischemia–reperfusion (I–R) injury. The aim of the present study was to determine whether NO or H2 directly protects heart or cells against I–R injury. Methods The heart isolated from 10-week-old male mouse (C57BL/6 J) was perfused using the Langendorff apparatus with H2- or NO-containing perfusate. The effect of each gas on coronary flow after global ischemia (GI) was evaluated. Myoblast cells (H9c2) were subjected to OGD (oxygen and glucose deprivation) for 2 h, followed by reoxygenation with medium containing normal oxygen (21%) with H2 or NO for 6 h. Viability of the cells was compared. Results Decrease in coronary flow observed after GI was significantly suppressed in the H2 group (P Conclusions Hydrogen can maintain the coronary flow and protect the myocardial cells, but NO may indirectly protect myocardia through the inhibition of platelet and neutrophil activation. Mechanism of the protection by H2 was considered to be different from that by NO, thereby being responsible for the strong protective effect observed when both gases were used simultaneously.

Characterization of the Spray Velocities from a Pressurized Metered-Dose Inhaler

Pressurized metered dose inhalers (pMDIs) are widely used to deliver aerosolized medications to the lungs, most often to relieve the symptoms of asthma. Over the past decade, pMDIs have been modified in several ways to eliminate the use of chlorofluorocarbons in their manufacture while increasing efficacy. Numerical simulations are being used more frequently to predict the flow and deposition of particles at various locations, both inside the respiratory tract as well as in pMDIs and add-on devices. These simulations require detailed information about the spray generated by a pMDI to ensure the validity of their results. This paper presents detailed, spatially resolved velocity measurements of the spray emitted from salbutamol sulfate pMDIs obtained using optically triggered particle image velocimetry (PIV). Instantaneous planar velocity measurements were taken and ensemble-averaged at nine different times during the spray event ranging from 1.3 to 100 msec after a pneumatically controlled actuation. The mean spray velocities were shown to be bimodal in time, with two velocity peaks and velocity magnitudes found to be much lower than published data from instantaneous single point measurements. Planar velocity data at each time step were analyzed to produce prescriptive velocity profiles suitable for use in numerical simulations. Spray geometry data are also reported. Statistical comparisons from several thousand individual spray events indicate that there is no significant difference in measured velocity among (1) two brands of pMDI canisters, (2) two pMDIs of the same brand but having different lot numbers, and (3) a full pMDI versus an almost empty pMDI. The addition of a secondary air flow of 30 SLPM (to represent simultaneous inhalation and spray actuation) deflected the spray downward but did not have a significant effect on flow velocity. Further experiments with an added cylindrical spacer revealed that within the spacer, the spray direction and cone angle were altered, although the peak velocities remained similar.

Physicochemical compatibility of mixtures of dornase alfa and tobramycin containing nebulizer solutions

Patients suffering from cystic fibrosis (CF) often need to inhale multiple doses of different nebulizable drugs per day. Patients attempt to shorten the time consuming administration procedure by mixing drug solutions/suspensions for simultaneous inhalation. The objective of this experimental study was to determine whether mixtures of the nebulizer solution dornase alfa (Pulmozyme) with tobramycin nebulizer solutions (TOBI and GERNEBCIN 80 mg) are physico-chemically compatible. Drug combinations were prepared by mixing the content of one respule Pulmozyme with either one respule TOBI or one ampoule GERNEBCIN 80 mg. Test solutions were stored at room temperature and exposed to light. Dornase alfa activity and tobramycin concentrations were determined by using a kinetic colorimetric DNase activity assay and a fluorescence immunoassay, respectively. Physical compatibility was determined by visual inspection and measurements of pH and osmolality. Tobramycin concentration was not affected by mixing the drug products. In spite of the high variability of the dornase alfa potency assay, it is obvious that activity is especially affected by sodium metabisulfite, used as excipient in GERNEBCIN. Patients should be advised, not to mix Pulmozyme with GERNEBCIN because of the incompatibility reaction. Further analytical studies are needed in order to determine the integrity and activity of dornase alfa in mixtures of Pulmozyme with TOBI. Finally clinical studies are necessary in order to demonstrate equivalent efficacy and safety of simultaneous inhalation in comparison to consecutive inhalation of both drugs.

Correlative Measurement of Four Biological Contaminants on Cotton Lint, and Their Implications for Occupational Health

Four biological contaminants of cotton fibers (gram-negative bacterial cells, endotoxin, fungal cells, and (1-3)-beta-D-glucan) were measured in 13 cotton lint samples from international origins, using traditional microbiological spread plating and adaptation of the Limulus amoebocyte lysate (LAL) assay. Correlations were evaluated using Spearman's rank correlation analyses. Contamination levels ranged from 713 +/- 212 to 216,830 +/- 30,413 CFU/g gram-negative bacteria; 281 +/- 29 to 9,250 +/- 820 CFU/g fungal cells; 8.30 +/- 0.89 to 137.89 +/- 21.55 ng/g endotoxin; and 15.96 +/- 5.18 to 2,964.42 +/- 313.90 LAL-reactive units/g glucan. Positive correlations existed between all contaminants; however, they were significant only between fungal cells and glucan (p < 0.05) and between endotoxin and glucan (p < 0.01). The highly significant positive correlation between endotoxin and glucan has implications for the health risk posed by the cotton-production environment, as simultaneous inhalation of these agents may cause or exacerbate lung inflammation.

Evaluation of pulmonary alveolar epithelial integrity by the detection of restriction to diffusion of hydrophilic solutes of different molecular sizes

The rate of transfer of a hydrophilic solute from the alveoli to pulmonary blood following inhalation as an aerosol depends on the molecular size of the solute and the permeability of the alveolar epithelium. The value of this measurement for assessing damage to the epithelium in lung disease is compromised by cigarette smoking, which accelerates clearance by unknown mechanisms. The rates of clearance of (99m)Tc-labelled diethylenetriaminepenta-acetic acid (DTPA) (molecular mass 492 Da) and (113m)In-labelled biotinylated DTPA (B-DTPA) (molecular mass 1215 Da) were monitored simultaneously by dynamic gamma-radiation camera imaging following simultaneous inhalation, and compared between eight normal non-smoking subjects and nine habitual cigarette smokers. The clearance rates of DTPA were 0.95 (S.D. 0.39)%/min in non-smokers and 4.13 (1.06) %/min in smokers. These were about twice the clearance rates of B-DTPA, which in the corresponding groups were 0.41 (0.26) and 2.12 (0.72)%/min respectively. The ratio of the B-DTPA/DTPA clearance rates was, in all subjects, less than the ratio (0.74) of the cube roots of the molecular masses of the solutes, assumed to correspond to the ratio of their free diffusion coefficients in water, and was not significantly different between smokers and non-smokers. As alveolar permeability increased, the ratio of clearance rates in the entire population showed a significant trend to increase in a non-linear fashion towards the value corresponding to the ratio of the free diffusion coefficients. We conclude that the diffusion of at least the larger of these two solutes through the pulmonary alveolar epithelium is restricted (i.e. associated with a reflection coefficient greater than zero). Cigarette smoking, however, does not appear to cause a loss of this restriction, and may increase solute clearance by other mechanisms, such as reducing fluid volume within the alveolus, thereby raising the local radiotracer concentration, or increasing the number of pores available for solute exchange without affecting pore size. Conversely, if restriction was lost in lung disease, the ratio of the clearance rates of two solutes of dissimilar sizes could be used to detect disease in smokers as well as non-smokers.

Dendritic cells are associated with augmentation of antigen sensitization by influenza A virus infection in mice.

To study the mechanisms responsible for enhanced sensitization of inhaled antigen in respiratory viral infections, we examined the contribution of dendritic cells (DC) and T lymphocytes to the development of inhalation sensitization during infection with influenza A virus in mice. BALB/c mice were sensitized by inhalation of ovalbumin (OA) from 3 to 7 days after the inoculation with influenza A virus, and were challenged with OA 3 weeks later. Airway responsiveness and serum OA-specific IgE were increased. The numbers of eosinophils and CD4(+) and CD8(+) T cells in bronchoalveolar lavage fluid were also increased. These changes were not observed in animals only sensitized with OA or only inoculated with the virus. In animals only inoculated with the virus, DC were immunohistochemically detected on the bronchial epithelium on days 2-5. With OA inhalation after virus inoculation, DC with high expression of MHC class II were retained for 5 weeks. These results show that influenza virus infection induces the migration of DC to the bronchial epithelium, and that simultaneous inhalation of antigen causes the loading of antigen-peptide / class II molecule complex on DC. Thus, the migration of DC in viral infection may play some role in the augmentation of antigen sensitization.

Early-onset inflammatory responses in vivo to adenoviral vectors in the presence or absence of lipopolysaccharide-induced inflammation.

Adenoviral vectors (Ad) have potential for use in pulmonary gene transfer for treating cystic fibrosis (CF). However, Ad may induce inflammation even in the absence of gene expression. Endotoxin from gram-negative bacteria in the airways of CF patients may also induce inflammation, and may further inhibit vector delivery and gene transfer. We used a mouse model to study the time course of Ad-induced lung inflammation and to assess additivity with lipopolysaccharide (LPS)-induced inflammatory responses. C3H/HeJ endotoxin-resistant (RES) mice hyporesponsive to inflammatory stimuli and normoresponsive C3HeB/FeJ endotoxin-sensitive (SEN) mice were studied to characterize inflammatory responses that follow intratracheal instillation of inactivated Ad, with or without simultaneous inhalation exposure to LPS. Instillation of 10(10) Ad particles dramatically increased bronchoalveolar lavage fluid (BALF) concentrations of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 at 3 to 6 h and induced profound neutrophilia, maximal at 12 to 24 h. SEN mice had tenfold greater responses than did RES mice at 6, 12, and 24 h. Mice exposed to Ad alone, LPS alone, or Ad + LPS had significant inflammation at the 3-h time point as demonstrated by BALF neutrophils, TNF-alpha, and IL-6. With all three treatments, SEN mice had a five- to 300-fold greater response than did RES mice. Importantly, Ad + LPS yielded no greater inflammatory response than LPS without Ad. These data demonstrate that replication-deficient Ad induce early inflammation and LPS-induced inflammation is not augmented by concurrent treatment with Ad.

Health effects of sulfur-related environmental air pollution. I. Executive summary.

The motivation of simulating real-world environmental exposure in a number of long-term studies with dogs was to address the question of whether or not perpetual inhalation of air pollutants can initiate diseases in healthy lungs and can thus contribute to the increasing prevalence of respiratory diseases in industrialized countries. The major conclusion of this article is that this question has to be answered in the negative for the simultaneous inhalation of the major constituents of combustion-related air pollution, particle-associated sulfur(IV), and particle-associated hydrogen ions. Over 13 mo, 8 healthy beagle dogs were exposed in 2 whole-body chambers daily for 16.5 h to 1 microm neutral sulfite [sulfur(IV)] particles at a mass concentration of 1.5 mg m-3 and for 6 h to 1.1 microm acidic sulfate particles carrying 15 micromol m-3 hydrogen ions into the canine lungs. This longitudinal study was characterized by repeated observations of individual respiratory response patterns. To establish baseline data the dogs were repeatedly examined preexposure while the chambers were ventilated over 16 mo with clean air. Each individual served thus as its own control. Another eight dogs served as additional controls. They were housed in 2 chambers ventilated with clean air over the entire study period of 29 mo. To assess response patterns, respiratory lung function tests were performed pre- and postexposure, segmental lung lavages were repeatedly performed to obtain epithelial lining fluid from the lungs for analysis of cell content, cell function, and biochemical indicators of lung injury, and radiolabeled test particles were used to study pathways of intrapulmonary particle elimination. At the end of the study, the lungs of all animals were morphologically and morphometrically examined. Functional and structural responses were finally compared to those observed previously as a result of a sole exposure of canine lungs to neutral sulfite particles over 10 mo (Heyder et al., 1992). Interactions between responses induced by neutral sulfite and acidic sulfate particles occurred, but antagonism rather than synergism was observed. The responses induced by sulfur(IV) were less pronounced, not detectable, or even reversed when hydrogen ions were also delivered to the lungs. On the other hand, responses not induced by the sole exposure to sulfur(IV) were observed: The activity of alkaline phosphatase was elevated and type II pneumocytes proliferated. It can, however, be concluded that long-term exposure of healthy lungs to particle-associated neutral sulfur(IV) and hydrogen ions at concentration close to ambient levels causes subtle respiratory responses but does not initiate pathological processes in the lungs. In other words, the perpetual inhalation of sulfur(IV) and hydrogen ions from the atmospheric environment presents no health risk to the healthy lungs. It is thus also very unlikely that respiratory diseases can be initiated by the inhalation of these pollutants.

Modulation of an Allergic Immune Response via the Mucosal Route in a Murine Model of Inhalative Type–I Allergy

A murine model of aerosol inhalation, leading to sensitization to birch pollen (BP) and its major allergen Bet v 1, was established in order to try to influence type–I allergic immune responses via the mucosal route. We previously demonstrated that simultaneous inhalation of BP and cholera toxin, a potent mucosal adjuvant, induced a Th1–like immune response to the allergen in naive mice and modulated allergic immune responses in sensitized mice. In contrast to cholera holotoxin, mucosal application of the cholera B subunit (CTB) conjugated to antigen has been shown to induce peripheral tolerance in certain models of Th1–based autoimmune diseases. In the present study we investigated the potential of such an antigen delivery system to suppress Th2–based, allergic immune responses. Mucosal administration of CTB/Bet v 1 conjugates prior to sensitization led to significantly increased allergen–specific IgE/IgG1 and IgG2a antibody levels and cytokine production (IL–5, IFN–γ) in vitro. Thus, CTB coupled to Bet v 1 acted as an adjuvant rather than a tolerogen. On the other hand we noted that mucosal application of CTB coupled to ovalbumin led to marked suppression of antigen–specific IgE antibody levels and IL–5 production in vitro and thereby restricted allergic sensitization. These results indicated that the effects of CTB/antigen conjugates depended on the nature of the antigen. In contrast to Bet v 1 coupled to CTB, nasal as well as oral application of low doses of unconjugated, Bet v 1 prior to aerosol sensitization inhibited allergen–specific antibody responses of all isotypes, cutaneous type–I skin tests in vivo as well as allergen–specific lymphoproliferative responses and cytokine production (IL–4, IL–5, IL–10, IFN–γ) in vitro, suggesting that both T– and B–cell tolerance to the allergen were induced. Taken together, mucosal tolerance induction as well as the use of certain transmucosal antigen delivery systems might be promising new strategies to modulate type–I allergic immune responses