Influence of Cigarette Aerosol in Alpha-Synuclein Oligomerization and Cell Viability in SH-SY5Y: Implications for Parkinson's Disease

Although cigarette aerosol exposure is associated with various adverse health issues, its impact on Parkinson's disease (PD) remains elusive. Here, we investigated the effect of cigarette aerosol extract (CAE) on SH-SY5Y cells for the first time, both with and without α-synuclein (α-Syn) overexpression. We found that α-Syn aggravates CAE-induced cell death, oxidative stress, and mitochondrial dysfunction. Fluorescence cross-correlation spectroscopy (FCCS) revealed a dual distribution of α-Syn within the cells, with homogeneous regions indicative of monomeric α-Syn and punctated regions, suggesting the formation of oligomers. Moreover, we observed colocalization of α-Syn oligomers with lysosomes along with a reduction in autophagy activity. These findings suggest that α-Syn overexpression exacerbates CAE-induced intracellular cytotoxicity, mitochondrial dysfunction, and autophagy dysregulation, leading to elevated cell mortality. Our findings provide new insights into the pathogenic mechanisms linking exposure to cigarette aerosols with neurodegenerative diseases.

A Comparative Study of the Effects of Electronic Cigarette and Traditional Cigarette on the Pulmonary Functions of C57BL/6 Male Mice

INTRODUCTION

Electronic cigarettes (E-cigs) are in a controversial state. Although E-cig aerosol generally contains fewer harmful substances than smoke from burned traditional cigarettes, aerosol along with other compounds of the E-cigs may also affect lung functions and promote the development of lung-related diseases. We investigated the effects of E-cig on the pulmonary functions of male C57BL/6 mice and reveal the potential underlying mechanisms.

METHODS

A total of 60 male C57BL/6 mice were randomly divided into four groups. They were exposed to fresh-air, traditional cigarette smoke, E-cig vapor with 12 mg/mL of nicotine, and E-cig with no nicotine for 8 weeks. Lung functions were evaluated by using quantitative analysis of the whole body plethysmograph, FlexiVent system, lung tissue histological and morphometric analysis, and RT-PCR analysis of mRNA expression of inflammation-related genes. In addition, the effects of nicotine and acrolein on the survival rate and DNA damage were investigated using cultured human alveolar basal epithelial cells.

RESULTS

Exposure to E-cig vapor led to significant changes in lung functions and structures including the rupture of the alveolar cavity and enlarged alveolar space. The pathological changes were also accompanied by increased expression of interleukin-6 and tumor necrosis factor-α.

CONCLUSIONS

The findings of the present study indicate that the safety of E-cig should be further evaluated.

IMPLICATIONS

Some people currently believe that using nicotine-free E-cigs is a safe way to smoke. However, our research shows that E-cigs can cause lung damage regardless of whether they contain nicotine.

Impact of air humidity on the tenacity of different agents in bioaerosols

Despite the variety of pathogens that are transmitted via the airborne route, few data are available on factors that influence the tenacity of airborne pathogens. In order to better understand and thus control airborne infections, knowledge of these factors is important. In this study, three agents, S. aureus, G. stearothermophilus spores and the MS2 bacteriophage, were aerosolized at relative humidities (RH) varying between 30% and 70%. Air samples were then analyzed to determine the concentration of the agents. S. aureus was found to have significantly lower survival rate in the aerosol at RH above 60%. It showed the lowest recovery rates of the three agents, ranging from 0.13% at approximately 70% RH to 4.39% at 30% RH. G. stearothermophilus spores showed the highest tenacity with recovery rates ranging from 41.85% to 61.73% with little effect of RH. For the MS2 bacteriophage, a significantly lower tenacity in the aerosol was observed with a recovery rate of 4.24% for intermediate RH of approximately 50%. The results of this study confirm the significant influence of the RH on the tenacity of airborne microorganisms depending on the specific agent. These data show that the behavior of microorganism in bioaerosols is varies under different environmental conditions.

CDC Guidelines for the Prevention and Treatment of Anthrax, 2023

This report updates previous CDC guidelines and recommendations on preferred prevention and treatment regimens regarding naturally occurring anthrax. Also provided are a wide range of alternative regimens to first-line antimicrobial drugs for use if patients have contraindications or intolerances or after a wide-area aerosol release of

Bacillus anthracis spores if resources become limited or a multidrug-resistant B. anthracis strain is used (Hendricks KA, Wright ME, Shadomy SV, et al.; Workgroup on Anthrax Clinical Guidelines. Centers for Disease Control and Prevention expert panel meetings on prevention and treatment of anthrax in adults. Emerg Infect Dis 2014;20:e130687; Meaney-Delman D, Rasmussen SA, Beigi RH, et al. Prophylaxis and treatment of anthrax in pregnant women. Obstet Gynecol 2013;122:885-900; Bradley JS, Peacock G, Krug SE, et al. Pediatric anthrax clinical management. Pediatrics 2014;133:e1411-36). Specifically, this report updates antimicrobial drug and antitoxin use for both postexposure prophylaxis (PEP) and treatment from these previous guidelines best practices and is based on systematic reviews of the literature regarding 1) in vitro antimicrobial drug activity against B. anthracis; 2) in vivo antimicrobial drug efficacy for PEP and treatment; 3) in vivo and human antitoxin efficacy for PEP, treatment, or both; and 4) human survival after antimicrobial drug PEP and treatment of localized anthrax, systemic anthrax, and anthrax meningitis.

Changes from previous CDC guidelines and recommendations include an expanded list of alternative antimicrobial drugs to use when first-line antimicrobial drugs are contraindicated or not tolerated or after a bioterrorism event when first-line antimicrobial drugs are depleted or ineffective against a genetically engineered resistant

B. anthracis strain. In addition, these updated guidelines include new recommendations regarding special considerations for the diagnosis and treatment of anthrax meningitis, including comorbid, social, and clinical predictors of anthrax meningitis. The previously published CDC guidelines and recommendations described potentially beneficial critical care measures and clinical assessment tools and procedures for persons with anthrax, which have not changed and are not addressed in this update. In addition, no changes were made to the Advisory Committee on Immunization Practices recommendations for use of anthrax vaccine (Bower WA, Schiffer J, Atmar RL, et al. Use of anthrax vaccine in the United States: recommendations of the Advisory Committee on Immunization Practices, 2019. MMWR Recomm Rep 2019;68[No. RR-4]:1-14). The updated guidelines in this report can be used by health care providers to prevent and treat anthrax and guide emergency preparedness officials and planners as they develop and update plans for a wide-area aerosol release of B. anthracis.

Comparative assessment of electronic nicotine delivery systems aerosol and cigarette smoke on endothelial cell migration: The Replica Project

Cigarette smoking is associated with impairment of repair mechanisms necessary for vascular endothelium homeostasis. Reducing the exposure to smoke toxicants may result in the mitigation of the harmful effect on the endothelium and cardiovascular disease development. Previous investigations evaluated in vitro the effect of electronic cigarette (EC) compared with cigarette smoke demonstrating a significant reduction in human umbilical vein endothelial cells (HUVECs) migration inhibition following EC aerosol exposure. In the present study, we replicated one of these studies, evaluating the effects of cigarette smoke on endothelial cell migration compared with aerosol from EC and heated tobacco products (HTPs). We performed an in vitro scratch wound assay on endothelial cells with a multi-center approach (ring-study) to verify the robustness and reliability of the results obtained in the replicated study, also testing the effect of aerosol from two HTPs on endothelial cells. Consistently with the original study, we observed a substantial reduction of the effects of aerosol from EC and HTPs on endothelial cell migration compared with cigarette smoke. While cigarette smoke reduced endothelial wound healing ability already at low concentrations (12.5%) and in a concentration-dependent manner, EC and HTPs aerosol showed no effect on endothelial cells until 80%-100% concentrations. In conclusion, our study further confirms the importance of EC and tobacco heated products as a possible harm reduction strategy for cardiovascular diseases development in smokers.

Pulmonary drug delivery and retention: A computational study to identify plausible parameters based on a coupled airway-mucus flow model

Pulmonary drug delivery systems rely on inhalation of drug-laden aerosols produced from aerosol generators such as inhalers, nebulizers etc. On deposition, the drug molecules diffuse in the mucus layer and are also subjected to mucociliary advection which transports the drugs away from the initial deposition site. The availability of the drug at a particular region of the lung is, thus, determined by a balance between these two phenomena. A mathematical analysis of drug deposition and retention in the lungs is developed through a coupled mathematical model of aerosol transport in air as well as drug molecule transport in the mucus layer. The mathematical model is solved computationally to identify suitable conditions for the transport of drug-laden aerosols to the deep lungs. This study identifies the conditions conducive for delivering drugs to the deep lungs which is crucial for achieving systemic drug delivery. The effect of different parameters on drug retention is also characterized for various regions of the lungs, which is important in determining the availability of the inhaled drugs at a target location. Our analysis confirms that drug delivery efficacy remains highest for aerosols in the size range of 1-5 μm. Moreover, it is observed that amount of drugs deposited in the deep lung increases by a factor of 2 when the breathing time period is doubled, with respect to normal breathing, suggesting breath control as a means to increase the efficacy of drug delivery to the deep lung. A higher efficacy also reduces the drug load required to be inhaled to produce the same health effects and hence, can help in minimizing the side effects of a drug.

Pulmonary drug delivery systems utilize the respiratory mechanism to directly deliver drugs to a target region of the lungs. The drug molecules deposit in the mucus lining, on reaching the target region, and are simultaneously transported away from the target region due to mucociliary transport and molecular diffusion. The availability of drugs at a target lung region and hence, efficacy of the drugs, therefore, determined by the delivery and retention of the drugs at the target region. The present study computationally solves the coupled transport equations to identify the conditions conducive for drug delivery and retention in the deep lungs. Drug delivery efficacy to the deep lung is observed to be highest for 1–5 μm aerosols. Breathing time period is also observed to influence efficacy. The amount of drugs deposited in the deep lung is observed to increase by a factor of 2 when the breathing time period is doubled with respect to normal breathing period. Such insights gained from this analysis will potentially help in devising mechanisms for increasing drug availability in the deep lung which is essential in achieving systemic drug delivery.

Targeted Drug Delivery Technologies Potentiate the Overall Therapeutic Efficacy of an Indole Derivative in a Mouse Cystic Fibrosis Setting

Inflammation plays a major role in the pathophysiology of cystic fibrosis (CF), a multisystem disease. Anti-inflammatory therapies are, therefore, of interest in CF, provided that the inhibition of inflammation does not compromise the ability to fight pathogens. Here, we assess whether indole-3-aldehyde (3-IAld), a ligand of the aryl hydrocarbon receptor (AhR), may encompass such an activity. We resorted to biopharmaceutical technologies in order to deliver 3-IAld directly into the lung, via dry powder inhalation, or into the gut, via enteric microparticles, in murine models of CF infection and inflammation. We found the site-specific delivery of 3-IAld to be an efficient strategy to restore immune and microbial homeostasis in CF organs, and mitigate lung and gut inflammatory pathology in response to fungal infections, in the relative absence of local and systemic inflammatory toxicity. Thus, enhanced delivery to target organs of AhR agonists, such as 3-IAld, may pave the way for the development of safe and effective anti-inflammatory agents in CF.

Kuanxiong aerosol inhibits apoptosis and attenuates isoproterenol-induced myocardial injury through the mitogen-activated protein kinase pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Kuanxiong aerosol (KXA) is a common clinical drug based on Fangxiang Wentong (FXWT) therapy in the treatment of angina pectoris. However, the pharmacological mechanism of KXA in the prevention and treatment of myocardial injury (MI) is not clear.

AIM OF THE STUDY

The purpose of this study was to explore the protective effect of KXA on isoproterenol (ISO)-induced MI in rats.

MATERIALS AND METHODS

The study included male Wistar Kyoto rats (age: 6 weeks). The rats were randomly divided into the following 5 groups (n = 6 per group): control group, ISO group, isosorbide mononitrate (ISMN) group (5 mg/kg), KXA-L group (0.1 mL/kg), and KXA-H group (0.3 mL/kg). The rats in the last three groups were given intragastric administration for 14 days, and rats in control group and ISO group were given the same amount of normal saline daily. ISO (120 mg/kg) was used to induce MI on the 13th and 14th days. We assessed electrocardiograms (ECGs), myocardial specific enzymes, histopathological changes, and apoptosis.

RESULTS

We found that KXA reduced the increase in the ST-segment amplitude (elevation or depression) and the levels of myocardial marker enzymes induced by ISO in MI rats, improved the pathological changes in myocardial tissue, and reduced cardiomyocyte apoptosis. At the same time, KXA significantly inhibited the up-regulation of caspase-3 and Bax expression and down-regulation of Bcl-2 expression induced by ISO. RNA sequencing showed that 90 up-regulated genes induced by ISO were down-regulated after KXA treatment, whereas 27 down-regulated genes induced by ISO were up-regulated after KXA treatment. In addition, KEGG pathway enrichment analysis showed that the mitogen-activated protein kinase (MAPK) signaling pathway may be an important target of KXA in the treatment of ISO-induced MI in rats. The results of RNA sequencing verified by Western blot analysis showed that KXA significantly inhibited the activation of the ISO-induced MAPK pathway.

CONCLUSIONS

KXA improves cardiac function in MI rats by inhibiting apoptosis mediated by the MAPK signaling pathway.

Aerosol 1,25-dihydroxyvitamin D3 supplementation: A strategy to boost anti-tumor innate immune activity

BACKGROUND

1,25-dihydroxyvitamin D3 [1,25(OH)2D3] plays a role in calcium homeostasis but can also exert immunomodulatory effects. In lungs, characterized by a particular immunosuppressive environment primarily due to the presence of alveolar macrophages (AM), 1,25(OH)2D3 has been shown to favor the immune response against pathogens. Here, we explored the ability of aerosolized 1,25(OH)2D3 to locally promote an anti-tumor phenotype in alveolar macrophages (AM) in the treatment of lung metastases.

METHODS

Cytotoxicity assay has been used to assess the capability of AM, in vitro treated of not with 1,25(OH)2D3, to stimulate NK cells. Sulforhodamine B (SRB) assay has been used to assess the effect of 1,25(OH)2D3 on MC-38 and B16 tumor cells in vitro growth. 1,25(OH)2D3 was aerosolized in immunocompetent mouse models to evaluate the effect of local administration of 1,25(OH)2D3 on in vivo growth of MC-38 and B16 tumor cells within lungs and on infiltrating immune cells.

RESULTS

In vitro incubation of naïve AM with 1,25(OH)2D3 improved their ability to stimulate NK cell cytotoxicity. In vivo aerosolized 1,25(OH)2D3 significantly reduced the metastatic growth of MC-38 colon carcinoma, a tumor histotype that frequently metastasizes to lung in human. Immune infiltrate obtained from digested lungs of 1,25(OH)2D3-treated mice bearing MC-38 metastases revealed an increased expression of MHCII and CD80 on AM and an up-modulation of CD69 expression on effector cells that paralleled a strong increased ability of these cells to kill MC-38 tumor in vitro.

CONCLUSIONS

Together, these data show that aerosol delivery can represent a feasible and novel approach to supplement 1,25(OH)2D3 directly to the lungs promoting the activation of local immunity against cancer.

Development and Characterization of Treprostinil Palmitil Inhalation Aerosol for the Investigational Treatment of Pulmonary Arterial Hypertension

Treprostinil palmitil (TP) is a prodrug of treprostinil (TRE), a pulmonary vasodilator that has been previously formulated for inhaled administration via a nebulizer. TP demonstrates a sustained presence in the lungs with reduced systemic exposure and prolonged inhibition of hypoxia-induced pulmonary vasoconstriction in vivo. Here, we report on re-formulation efforts to develop a more convenient solution-based metered-dose inhaler (MDI) formulation of TP, a treprostinil palmitil inhalation aerosol (TPIA) that matches the pharmacokinetic (PK) and efficacy profile of a nebulized TP formulation, treprostinil palmitil inhalation suspension (TPIS). MDI canisters were manufactured using a two-stage filling method. Aerosol performance, formulation solubility, and chemical stability assays were utilized for in vitro evaluation. For in vivo studies, TPIA formulations were delivered to rodents using an inhalation tower modified for MDI delivery. Using an iterative process involving evaluation of formulation performance in vitro (TP and excipient solubility, chemical stability, physical stability, and aerosol properties) and confirmatory testing in vivo (rat PK and efficacy, guinea pig cough), a promising formulation was identified. The optimized formulation, TPIA-W, demonstrates uniform in vitro drug delivery, a PK profile suitable for a once-daily administration, efficacy lasting at least 12 h in a hypoxic challenge model, and a significantly higher cough threshold than the parent drug treprostinil.

Chemical Elements in Electronic Cigarette Solvents and Aerosols Inhibit Mitochondrial Reductases and Induce Oxidative Stress

INTRODUCTION

Chemical elements and their toxicity were evaluated in electronic cigarette (EC) solvents, fluids, and aerosols.

AIMS AND METHODS

Element identification and quantification in propylene glycol (PG), glycerin (G), refill fluids before and after use, and aerosols was done using inductively coupled plasma optical emission spectrometry. Cytotoxicity and oxidative stress were evaluated using in vitro assays.

RESULTS

Seven elements were present in PG, G, and popular refill fluids, and they transferred to aerosols made with ECs. Selenium was in all products (0.125-0.292 mg/L), while arsenic, aluminum, and tin were frequently in solvent and refill fluid samples at lower concentrations. Iron, chromium, copper, nickel, zinc, and lead were only detected in fluid after EC use, indicating they came from heated atomizers. Elements transferred most efficiently to aerosols made with second-/third-generation ECs. Of the elements in fluid, selenium and arsenic were the most cytotoxic to human bronchial epithelial cells (BEAS-2B) and pulmonary fibroblasts in the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay. Selenium increased superoxide production in mitochondria and nucleoli and elevated selenoprotein H in nucleoli of BEAS-2B cells at concentrations found in EC aerosols (10 nM or 0.002 mg/L).

CONCLUSIONS

Elements in EC aerosols came from both e-fluids and atomizing units. Within second-/third-generation products, transfer became more efficient as power increased. In vitro responses occurred at concentrations of selenium found in some EC aerosols. Human exposure to chemical elements in ECs could be reduced by regulating (decreasing) allowable EC power and by improving the purity of PG and G.

IMPLICATIONS

PG, G, refill fluids, and e-fluids contained potentially toxic chemical elements that transferred to aerosols. Transfer was more efficient in second- and third-generation EC products and increased as power increased. Selenium and arsenic were the most cytotoxic of the elements tested in the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay. Selenium tetrachloride-induced oxidative stress in BEAS-2B cells, but not in human pulmonary fibroblasts. All fluids contained selenium above the concentration that induced oxidative stress in human bronchial epithelial cells. Selenium increased superoxide in mitochondria and nucleoli and increased selenoprotein H, a redox responsive DNA-binding protein that is upregulated by superoxide and an indicator of nucleolar stress. EC users are exposed to elements in aerosols, which may with chronic exposure contribute to diseases associated with oxidative stress.

Correlation and clinical relevance of animal models for inhaled pharmaceuticals and biopharmaceuticals

Nonclinical studies are fundamental for the development of inhaled drugs, as for any drug product, and for successful translation to clinical practice. They include in silico, in vitro, ex vivo and in vivo studies and are intended to provide a comprehensive understanding of the inhaled drug beneficial and detrimental effects. To date, animal models cannot be circumvented during drug development programs, acting as surrogates of humans to predict inhaled drug response, fate and toxicity. Herein, we review the animal models used during the different development stages of inhaled pharmaceuticals and biopharmaceuticals, highlighting their strengths and limitations.

In Vitro Toxicity and Chemical Characterization of Aerosol Derived from Electronic Cigarette Humectants Using a Newly Developed Exposure System

In the United States, the recent surge of electronic cigarette (e-cig) use has raised questions concerning the safety of these devices. This study seeks to assess the pro-inflammatory and cellular stress effects of the vaped humectants propylene glycol (PG) and glycerol (GLY) on airway epithelial cells (16HBE cells and differentiated human bronchial epithelial cells) with a newly developed aerosol exposure system. This system allows for chemical characterization of e-cig generated aerosol particles as well as in vitro exposures of 16HBE cells at an air-liquid interface to vaped PG and GLY aerosol. Our data demonstrate that the process of vaping results in the formation of PG- and GLY-derived oligomers in the aerosol particles. Our in vitro data demonstrate an increase in pro-inflammatory cytokines IL-6 and IL-8 levels in response to vaped PG and GLY exposures. Vaped GLY also causes an increase in cellular stress signals HMOX1, NQO1, and carbonylated proteins when the e-cig device is operated at high wattages. Additionally, we find that the exposure of vaped PG causes elevated IL-6 expression, while the exposure of vaped GLY increases HMOX1 expression in human bronchial epithelial cells when the device is operated at high wattages. These findings suggest that vaporizing PG and GLY results in the formation of novel compounds and the exposure of vaped PG and GLY are detrimental to airway cells. Since PG and/or GLY is universally contained in all e-cig liquids, we conclude that these components alone can cause harm to the airway epithelium.

Isoprene-Derived Secondary Organic Aerosol Induces the Expression of MicroRNAs Associated with Inflammatory/Oxidative Stress Response in Lung Cells

Exposure to fine particulate matter (PM2.5), of which secondary organic aerosol (SOA) is a major constituent, is linked to adverse health outcomes, including cardiovascular disease, lung cancer, and preterm birth. Atmospheric oxidation of isoprene, the most abundant nonmethane hydrocarbon emitted into Earth's atmosphere primarily from vegetation, contributes to SOA formation. Isoprene-derived SOA has previously been found to alter inflammatory/oxidative stress genes. MicroRNAs (miRNAs) are epigenetic regulators that serve as post-transcriptional modifiers and key mediators of gene expression. To assess whether isoprene-derived SOA alters miRNA expression, BEAS-2B lung cells were exposed to laboratory-generated isoprene-derived SOA constituents derived from the acid-driven multiphase chemistry of authentic methacrylic acid epoxide (MAE) or isomeric isoprene epoxydiols (IEPOX) with acidic sulfate aerosol particles. These IEPOX- and MAE-derived SOA constituents have been shown to be measured in large quantities within PM2.5 collected from isoprene-rich areas affected by acidic sulfate aerosol particles derived from human activities. A total of 29 miRNAs were identified as differentially expressed when exposed to IEPOX-derived SOA and 2 when exposed to MAE-derived SOA, a number of which are inflammatory/oxidative stress associated. These results suggest that miRNAs may modulate the inflammatory/oxidative stress response to SOA exposure, thereby advancing the understanding of airway cell epigenetic response to SOA.

Aerosolizable Marine Phycotoxins and Human Health Effects: In Vitro Support for the Biogenics Hypothesis

Respiratory exposure to marine phycotoxins is of increasing concern. Inhalation of sea spray aerosols (SSAs), during harmful Karenia brevis and Ostreopsis ovata blooms induces respiratory distress among others. The biogenics hypothesis, however, suggests that regular airborne exposure to natural products is health promoting via a downregulation of the mechanistic target of rapamycin (mTOR) pathway. Until now, little scientific evidence supported this hypothesis. The current explorative in vitro study investigated both health-affecting and potential health-promoting mechanisms of airborne phycotoxin exposure, by analyzing cell viability effects via cytotoxicity assays and effects on the mTOR pathway via western blotting. To that end, A549 and BEAS-2B lung cells were exposed to increasing concentrations (ng·L⁻¹–mg·L⁻¹) of (1) pure phycotoxins and (2) an extract of experimental aerosolized homoyessotoxin (hYTX). The lowest cell viability effect concentrations were found for the examined yessotoxins (YTXs). Contradictory to the other phycotoxins, these YTXs only induced a partial cell viability decrease at the highest test concentrations. Growth inhibition and apoptosis, both linked to mTOR pathway activity, may explain these effects, as both YTXs were shown to downregulate this pathway. This proof-of-principle study supports the biogenics hypothesis, as specific aerosolizable marine products (e.g., YTXs) can downregulate the mTOR pathway.

Inactivation kinetics of Geobacillus stearothermophilus spores by a peracetic acid or hydrogen peroxide fog in comparison to the liquid form

The aim of this study was to compare the sporicidal effect of the disinfectants peracetic acid (PAA) or hydrogen peroxide (H₂O₂) applied as a fog or as a liquid. The efficacy of fogging of the disinfectants was tested in a closed isolator cabinet using highly heat and chemical-resistant spores of Geobacillus stearothermophilus. Fogging of a 0.06% solution of PAA resulted in over 5-log reduction of spores in 10 min, whereas for PAA used in liquid form the same reduction was achieved in 4.5 min. The inactivation curves for fog and liquid were fitted using three different models (Linear with shoulder, Weibull, Gauss-Eyring). This showed a shoulder for the fog with an estimated length of 4.1 min, but the D values, calculated for the linear parts of the curves, were not significantly different (1.1 and 0.8 min for the PAA fog and solution, respectively). Similar results were obtained for a 12% H₂O₂ solution, albeit that H₂O₂ was less effective compared to PAA, requiring 60 min to reach 3-log reduction when applied as a fog, with an estimated shoulder of 18.5 min. Fogging of a 0.06% peracetic acid solution effectively inactivated G. stearothermophilus spores. Overall, the data show that fogging can be an effective method of applying disinfectants but that a shoulder in the inactivation curves should be considered in process design. This study provides inactivation kinetics for disinfection using PAA or H₂O₂-based fog, which can aid in selection and validation of process parameters for disinfection of contained areas by fogging.

Effects of spraying nano-materials on the absorption of metal(loid)s in cucumber

This report investigates the spraying of nano-silica and fullerene on cucumber leaves to expose their ability to reduce the toxicity and uptake of metal(loid)s. Cucumber seedlings were randomly divided into six treatment groups: 10 mg/L nano-SiO2, 20 mg/L nano-SiO2, 10 mg/L Fullerene, 20 mg/L Fullerene, 5 mg/L Fullerene + 5 mg/L nano-SiO2, and 10 mg/L Fullerene + 10 mg/L nano-SiO2. Nano-silica-treated plants exhibited evidence of the potential mitigation of metal(loid)s poisoning. Specifically, results showed that 20 mg/L of nano-silica promoted Cd uptake by plants; comparatively, 10 mg/L of nano-silica did not significantly increase the silicon content in plants. Both low-concentration combined treatment and low-concentration fullerene groups inhibited metal(loid)s uptake by plants. Scanning electron microscopy (SEM) was then used to observe the surface morphology of cucumber leaves. Significant differences were observed on disease resistance in plants across the different nano-material conditions. Collectively, these findings suggest that both nano-silica materials and fullerene have the potential to control metal(loid)s toxicity in plants.

In vitro and ex vivo evaluation of the biological performance of sclerosing foams

Since the first reports on foam sclerotherapy, multiple studies have been conducted to determine the physical properties and behavior of foams, but relatively little is known about their biological effects on the endothelial cells lining the vessel wall. Moreover, a systematic comparison of the biological performance of foams produced with different methods has not been carried out yet. Herein, a 2D in vitro method was developed to compare efficacy of commercially available polidocanol injectable foam (PEM, Varithena) and physician-compounded foams (PCFs). Endothelial cell attachment upon treatment with foam was quantified as an indicator of therapeutic efficacy, and was correlated with foam physical characteristics and administration conditions. An ex vivo method was also developed to establish the disruption and permeabilisation of the endothelium caused by sclerosing agents. It relied on the quantitation of extravasated bovine serum albumin conjugated to Evans Blue, as an indicator of endothelial permeability. In our series of comparisons, PEM presented a greater overall efficacy compared to PCFs, across the different biological models, which was attributed to its drainage dynamics and gas formulation. This is consistent with earlier studies that indicated superior physical cohesiveness of PEM compared to PCFs.

Fate of Barium Sulfate Nanoparticles Deposited in the Lungs of Rats

We have shown that barium [from BaSO4 nanoparticles (NPs)] was cleared from the lungs faster than other poorly soluble NPs and translocated mostly to bone. We now studied barium biokinetics in rats during Study 1: two-year inhalation exposure to 50 mg/m3 BaSO4 NP aerosols, and Study 2: single intratracheal (IT) instillation of increasing doses of BaSO4 NPs or BaCl2. Study 1 showed that lung barium content measured by inductively coupled plasma mass spectrometry increased during 360 days of BaSO4 NP aerosol exposures. An equilibrium was established from that time until 2 years. Barium concentrations in BaSO4-exposed animals were in the order (lungs > lymph nodes > hard bone > bone marrow > liver). In Study 2, there was an increase in lung barium post-IT instillation of BaSO4 NPs while barium from BaCl2 was mostly cleared by day 28. Transmission electron microscopy showed intact BaSO4 NPs in alveolar macrophages and type II epithelial cells, and in tracheobronchial lymph nodes. Using stimulated Raman scattering microscopy, specific BaSO4 Raman spectra were detected in BaSO4 NP-instilled lungs and not in other organs. Thus, we posit that barium from BaSO4 NPs translocates from the lungs mainly after dissolution. Barium ions are then incorporated mostly into the bone and other organs.

Aerosol technique-based carbon-encapsulated hollow mesoporous silica nanoparticles for synergistic chemo-photothermal therapy

Near-infrared (NIR)-responsive drug delivery systems have enhanced tumor ablative efficiency through permeation and retention effects. Graphene oxide (GO) has shown great potential both in photothermal therapy and in drug delivery. Thus, in this study, we designed an ambient spark-generated GO, wrapped on topotecan (TPT)-loaded hollow mesoporous silica nanoparticles (HMSN-NH2-TPT-CGO), to function as an efficient platform for pH-dependent sustained release of TPT. HMSN-NH2-TPT-CGO also exhibited a combined chemo-photothermal effect within a single carrier system. This developed system was stable with a uniform particle size (∼190 nm) and was demonstrated to possess a sufficient heat-absorbing capacity to induce tumor cell ablation. We performed the ablation of tumor cells both in vitro and in vivo in combination with photothermal therapy and chemotherapy using the spark-generated functional GO and HMSN. The prepared nanocarriers demonstrated high cellular uptake, apoptosis, and G0/G1 cell cycle arrest. In vivo study using the MDA-MB-231 xenograft model revealed the ultraefficient tumor ablative performance of HMSN-NH2-TPT-CGO compared with that of free TPT, with no toxic effect on vital organs. Altogether, the optimized nanocarriers presented a significant potential to act as a vehicle for cancer treatment. STATEMENT OF SIGNIFICANCE: This is the first study that uses spark-generated graphene oxide nanoflakes to cover the topotecan (TPT)-loaded hollow mesoporous silica nanoparticles (HMSNs) to treat breast cancer. Dense silica was used as a hard template to prepare the HMSNs attributing to a high drug payload. The concentration of Na₂CO₃ was precisely controlled to minimize the silica etching time within 70 min. The use of the nanographene flakes served a dual purpose, first, by acting as a capping agent to prevent the premature release of drug and, second, by serving as a nano heater that significantly ablates the tumor cells. The prepared nanocarriers (NCs) exhibited effective and enhanced in vitro and in vivo apoptosis, as well as significant tumor growth inhibition even after 15 days of treatment time, with no toxic effect to the vital organs. The NCs enhanced in vitro tumor cell killing effects and served as an effective carrier for in vivo tumor regression, thereby highlighting the enormous potential of this system for breast cancer therapy.

Cellular and Acellular Assays for Measuring Oxidative Stress Induced by Ambient and Laboratory-Generated Aerosols

INTRODUCTION

Many studies have established associations between exposure to air pollution, or atmospheric particulate matter (PM), and adverse health effects. An increasing array of studies have suggested oxidative stress as a possible mechanism by which PM-induced health effects arise, and as a result, many chemical and cellular assays have been developed to study PM-induced oxidant production. Although significant progress has been made in recent years, there are still many gaps in this area of research that have not been addressed. Many prior studies have focused on the aerosol of primary origin (e.g., the aerosol emitted from combustion engines) although the aerosol formed from the oxidation of volatile species, secondary organic aerosol (SOA), has been shown to be the predominant type of aerosol even in urban areas. Current SOA health studies are limited in number, and as such, the health effects of SOA are poorly characterized. Also, there is a lack of perspective in terms of the relative toxicities of different SOA systems. Additionally, although chemical assays have identified some SOA constituents associated with adverse health endpoints, the applicability of these results to cellular responses has not been well established.

SPECIFIC AIMS

The overall objective of this study was to better understand the oxidative properties of different types and components of PM mixtures (especially SOA) through systematic laboratory chamber experiments and ambient field studies. The study had four specific aims.

1 To develop a cellular assay optimized for measuring reactive oxygen and nitrogen species (ROS/RNS) production resulting from PM exposure and to identify a robust parameter that could represent ROS/RNS levels for comparison with different endpoints.

2 To identify ambient PM components associated with ROS/RNS production and evaluate whether results from chemical assays represented cellular responses in terms of ROS/RNS production.

3 To investigate and provide perspective on the relative toxicities of SOA formed from common biogenic and anthropogenic precursors under different conditions (e.g., humidity, nitrogen oxides [NOx], and redox-active metals) and identify bulk aerosol properties associated with cellular responses.

4 To investigate the effects of photochemical aging on aerosol toxicity.

METHODS

Ambient PM samples were collected from urban and rural sites in the greater Atlanta area as part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study between June 2012 and October 2013. The concentrations of water-soluble species (e.g., water-soluble organic carbon [WSOC], brown carbon [Br C], and metals) were characterized using a variety of instruments. Samples for this study were chosen to span the observed range of dithiothreitol (DTT) activities.

Laboratory studies were conducted in the Georgia Tech Environmental Chamber (GTEC) facility in order to generate SOA under well-controlled photooxidation conditions. Precursors of biogenic origin (isoprene, α-pinene, and β-caryophyllene) and anthropogenic origin (pentadecane, m-xylene, and naphthalene) were oxidized under various formation conditions (dry vs. humid, NOx, and ammonium sulfate vs. iron sulfate seed particles) to produce SOA of differing chemical composition and mass loading. For the naphthalene system, a series of experiments were conducted with different initial hydrocarbon concentrations to produce aerosols with various degree of oxidation. A suite of instruments was utilized to monitor gas- and particle-phase species. Bulk aerosol properties (e.g., O:C, H:C, and N:C ratios) were measured using a high-resolution time-of-flight aerosol mass spectrometer. Filter samples were collected for chemical oxidative potential and cellular measurements. For the naphthalene system, multiple filter samples were collected over the course of a single experiment to collect aerosols of different photochemical aging.

For all filter samples, chemical oxidative potentials were determined for water-soluble extracts using a semiautomated DTT assay system. Murine alveolar macrophages and neonatal rat ventricular myocytes were also exposed to PM samples extracted in cell culture medium to investigate cellular responses. ROS/RNS production was detected using the intracellular ROS/RNS probe, carboxy-2',7'-dichlorodihydrofluorescein diacetate (carboxy-H2DCFA), whereas cellular metabolic activity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Finally, cytokine production, that is, secreted levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), were measured post-exposure using an enzyme-linked immunosorbent assay (ELISA). To identify PM constituents associated with oxidative properties, linear regressions between oxidative properties (cellular responses or DTT activity) and aerosol composition (metals, elemental ratios, etc.) were evaluated using Pearson's correlation coefficient, where the significance was determined using multiple imputation and evaluated using a 95% confidence interval.

RESULTS

We optimized several parameters for the ROS/RNS assay, including cell density (2 × 104 cells/well for macrophages and 3.33 × 104 cells/well for cardiomyocytes), probe concentration (10 µM), and sample incubation time (24 hours). Results from both ambient and laboratory-generated aerosols demonstrate that ROS/RNS production was highly dose-dependent and nonlinear with respect to PM dose. Of the dose-response metrics investigated in this study (maximum response, dose at which the response is 10% above the baseline [threshold], dose at which 50% of the response is attained [EC50], rate at which the maximum response is attained [Hill slope], and area under the dose-response curve [AUC]), we found that the AUC was the most robust parameter whose informativeness did not depend on dose range.

A positive, significant correlation was observed between ROS/RNS production as represented by AUC and chemical oxidative potential as measured by DTT for ambient samples collected in summer. Conversely, a relatively constant AUC was observed for ambient samples collected in winter regardless of the corresponding DTT activity. We also identified several PM constituents (WSOC, BrC, iron, and titanium) that were significantly correlated with AUC for summer samples. The strong correlation between organic species and ROS/RNS production highlights a need to understand the contribution of organic aerosols to PM-induced health effects. No significant correlations were observed for other ROS/RNS metrics or PM constituents, and no spatial trends were observed.

For laboratory-generated aerosol, precursor identity influenced oxidative potentials significantly, with isoprene and naphthalene SOA having the lowest and highest DTT activities, respectively. Both precursor identity and formation condition significantly influenced inflammatory responses induced by SOA exposure, and several response patterns were identified for SOA precursors whose photooxidation products share similar carbon-chain length and functionalities. The presence of iron sulfate seed particles did not have an apparent effect on oxidative potentials; however, a higher level of ROS/RNS production was observed for all SOA formed in the presence of iron sulfate compared with ammonium sulfate. We also identified a significant positive correlation between ROS/RNS production and average carbon oxidation state, a bulk aerosol property. It may therefore be possible to roughly estimate ROS/RNS production using this property, which is readily obtainable. This correlation may have significant implications as aerosols have an atmospheric lifetime of a week, during which average carbon oxidation state increases because of atmospheric photochemical aging. Our results suggest that aerosols might become more toxic as they age in the atmosphere. Finally, in the context of ambient samples, laboratory-generated SOA induced comparable or higher levels of ROS/RNS. Oxidative potentials for all laboratory SOA systems, with the exception of naphthalene (which was higher), were all comparable with oxidative potentials observed in ambient samples.

In vitro RNA-seq-based toxicogenomics assessment shows reduced biological effect of tobacco heating products when compared to cigarette smoke

The battery of regulatory tests used to evaluate the risk of novel tobacco products such as heated tobacco products (THPs) presents some limitations including a bias towards the apical endpoint tested, and limited information on the mode of action. This is driving a paradigm shift to more holistic systems biology approaches. In this study, we used RNA-sequencing to compare the transcriptomic perturbations following acute exposure of a 3D airway tissue to the aerosols from two commercial THPs and a reference 3R4F cigarette. 2809 RNAs were differentially expressed for the 3R4F treatment and 115 and 2 RNAs for the two THPs (pFDR < 0.05, FC > 1.5), respectively. The relationship between the identified RNA features and gene ontologies were mapped showing a strong association with stress response, xenobiotics metabolism, and COPD-related terms for 3R4F. In contrast, fewer ontologies were found enriched for the THPs aerosols. "Response to wounding" was a common COPD-related term over-represented for the two THPs but at a reduced significance. Quantification of a cytokine panel post-exposure confirmed a pro-inflammatory effect of cigarette smoke but not for THPs. In conclusion, THPs have a reduced impact on gene expression compared to 3R4F.

Effect of epicuticular wax crystals on the localization of artificially deposited sub-micron carbon-based aerosols on needles of Cryptomeria japonica

Elucidation of the mechanism of adsorption of particles suspended in the gas-phase (aerosol) to the outer surfaces of leaves provides useful information for understanding the mechanisms of the effect of aerosol particles on the growth and physiological functions of trees. In the present study, we examined the localization of artificially deposited sub-micron-sized carbon-based particles on the surfaces of needles of Cryptomeria japonica, a typical Japanese coniferous tree species, by field-emission scanning electron microscopy. The clusters (aggregates) of carbon-based particles were deposited on the needle surface regions where epicuticular wax crystals were sparsely distributed. By contrast, no clusters of the particles were found on the needle surface regions with dense distribution of epicuticular wax crystals. Number of clusters of carbon-based particles per unit area showed statistically significant differences between regions with sparse epicuticular wax crystals and those with dense epicuticular wax crystals. These results suggest that epicuticular wax crystals affect distribution of carbon-based particles on needles. Therefore, densely distributed epicuticular wax crystals might prevent the deposition of sub-micron-sized carbon-based particles on the surfaces of needles of Cryptomeria japonica to retain the function of stomata.

Knockdown of Fruit Flies by Imidacloprid Nanoaerosol

This report describes the effects of nanoaerosol particles (NAPs) from imidacloprid (IMI) on fruit flies. NAPs were produced using a newly developed generator which employs electro-hydrodynamic atomization of IMI solution in ethanol. Exposure of Drosophila melanogaster to the IMI NAPs at a concentration of C = 2.7 ± 0.1 ng/cm(3) caused knockdown in half of the flies in T50 = 88 ± 14 min at 22 °C and in T50 = 36 ± 2 min at 33 °C. A number of special experiments precluded IMI volatilization and contact or oral action of IMI upon exposure to the NAPs. It was shown that only the fraction of NAPs in the size range of 7-300 nm is responsible for the knockdown and that dependence of T50 on the NAPs' fraction mass follows Haber's rule, C × T50 = const. Comparison with the oral doses obtained when flies were fed an IMI-sucrose mixture revealed that the inhaled doses that caused knockdown were 2 orders of magnitude lower than the oral ones. This new technology may be used to quickly eliminate insects with nanoaerosols of nonvolatile insecticides in greenhouses and other closed environments.

[The influence of the nasal septum tubercle on certain aerodynamic characteristics]

The objective of the present work was to investigate the influence of the tubercle of the nasal septum thickening on the localization of the regions of precipitation of aerosol particles in the nasal cavity under the experimental conditions. The experiment was conducted using the newly developed 3D stereolithographic model of the nasal cavity. The study has demonstrated that the tubercle of the nasal septum thickening is an aerodynamically-conditioned normal anatomical structure, and its absence deteriorates the aerodynamic characteristics of the airflow through the nasal cavity.

Disinfection efficiency of chlorine dioxide gas in student cafeterias in Taiwan

In Taiwan, the food and drink requirements of students and faculty members are met by student cafeterias. The air quality within these cafeterias should satisfy the guidelines laid down by the Taiwan Environmental Protection Agency (Taiwan EPA). Accordingly, this study performed an experimental investigation into the efficiency of two different gaseous chlorine dioxide (ClO2) treatments in disinfecting a local student cafeteria, namely a single, one-off application and a twice-daily application. In both cases, the ClO2 was applied using strategically placed aerosol devices. The air quality before and after disinfection was evaluated by measuring the bioaerosol levels of bacteria and fungi. Moreover, a stepwise discriminant analysis method was applied for predicting the residual concentrations of bacteria and fungi, as a function of the environmental parameters and the ClO2 concentration. The experimental results showed that the average background levels of bacteria and fungi prior to ClO2 disinfection were 972.5 +/- 623.6 and 1534.1 +/- 631.8 colony-forming units (CFU)/m3, respectively. A single ClO2 application was found to reduce the bacterial and fungal concentration levels by as much as 65% and 30%, respectively. By contrast, a twice-daily ClO2 application was found to reduce the bacterial and fungal concentration levels by as much as 74% and 38%, respectively. The statistical analysis results showed that the residual bacterial concentration level was determined primarily by the number of individuals present in the cafeteria, the temperature, and the ClO2 concentration, whereas the residual fungal concentration level was determined mainly by the temperature, the total number of suspended particles, and the ClO2 concentration. Thus, the integrated results suggest that the air quality guidelines prescribed by the Taiwan EPA for student cafeteria can best be achieved by applying ClO2 twice daily using an appropriate deployment of aerosol devices.

IMPLICATIONS

ClO2 gas can destroy all manner of microorganisms, including bacteria, spores, fungi, viruses, and even protozoans, in indoor environments. Moreover, it is popularly known that bioaerosols are able to grow and propagate on a wide variety of building materials and indoor surfaces. Thus, through optimal ClO2 disinfection methodology, the indoor microbial contaminants can be decreased and the residual concentrations of bacteria and fungi as a function of the environmental parameters and the ClO2 concentration can be predicted via some statistical techniques.

Enhancing bioaerosol sampling by Andersen impactors using mineral-oil-spread agar plate

As a bioaerosol sampling standard, Andersen type impactor is widely used since its invention in 1950s, including the investigation of the anthrax attacks in the United States in 2001. However, its related problems such as impaction and desiccation stress as well as particle bounce have not been solved. Here, we improved its biological collection efficiencies by plating a mineral oil layer (100 µL) onto the agar plate. An Andersen six-stage sampler and a BioStage impactor were tested with mineral-oil-spread agar plates in collecting indoor and outdoor bacterial and fungal aerosols. The effects of sampling times (5, 10 and 20 min) were also studied using the BioStage impactor when sampling environmental bioaerosols as well as aerosolized Bacillus subtilis (G+) and Escherichia coli (G-). In addition, particle bounce reduction by mineral-oil-plate was also investigated using an optical particle counter (OPC). Experimental results revealed that use of mineral-oil-spread agar plate can substantially enhance culturable bioaerosol recoveries by Andersen type impactors (p-values<0.05). The recovery enhancement was shown to depend on bioaerosol size, type, sampling time and environment. In general, more enhancements (extra 20%) were observed for last stage of the Andersen six-stage samplers compared to the BioStage impactor for 10 min sampling. When sampling aerosolized B. subtilis, E. coli and environmental aerosols, the enhancement was shown to increase with increasing sampling time, ranging from 50% increase at 5 min to ∼100% at 20 min. OPC results indicated that use of mineral oil can effectively reduce the particle bounce with an average of 66% for 10 min sampling. Our work suggests that enhancements for fungal aerosols were primarily attributed to the reduced impaction stress, while for bacterial aerosols reduced impaction, desiccation and particle bounce played major roles. The developed technology can readily enhance the agar-based techniques including those high volume portable samplers for bioaerosol monitoring.

Dynamic growth and deposition of hygroscopic aerosols in the nasal airway of a 5-year-old child

Hygroscopic growth within the human respiratory tract can be significant, which may notably alter the behavior and fate of the inhaled aerosols. The objective of this study is to evaluate the hygroscopic effects upon the transport and deposition of nasally inhaled fine-regime aerosols in children. A physiologically realistic nasal-laryngeal airway model was developed based on magnetic resonance imaging of a 5-year-old boy. Temperature and relative humidity field were simulated using the low Reynolds number k - ε turbulence model and chemical specie transport model under a spectrum of four thermo-humidity conditions. Particle growth and transport were simulated using a well validated Lagrangian tracking model coupled with a user-defined hygroscopic growth module. The subsequent aerosol depositions for the four inhalation scenarios were evaluated on a multiscale basis such as total, subregional, and cellular-level depositions. Results of this study show that a supersaturated humid environment is possible in the nasal turbinate region and can lead to significant condensation growth (d / d(0)  > 10) of nasally inhaled aerosols. Depositions in the nasal airway can also be greatly enhanced by condensation growth with appropriate inhalation temperature and humidity. For subsaturated and mild inhalation conditions, the hygroscopic effects were found to be nonsignificant for total depositions, while exerting a large impact upon localized depositions.

Evaluation of an aerosol emitter for mating disruption of Cydia pomonella in Italy

Some techniques have been developed to disrupt mating (MD) of codling moth (CM) by treating orchards with pheromone. Synthetic pheromone is applied to the crop as a formulation that is designed to protect these generally labile compounds from degradation while gradually releasing pheromone into the atmosphere. In Trentino South Tyrol MD has been adopted successfully (24,500 ha, i.e. 73% of the apple area) to control CM in heavily infested areas; while in areas with low pest pressure, less pesticides are usually applied (2-3 per year) and as a consequence, pheromone mating disruption is not considered economically convenient. Hand applied sealed plastic tubes and plastic ampoules are the two pheromone formulations more widely used. A new pheromone-based control technique, called Puffer, has been recently proposed. Puffers are battery-powered devices that release pheromone from pressurized aerosol cans every 15 minutes for 12 hours or 30 min for 24 hours. During each puff a quantity of 6.95 mg a.i. is emitted. The high release rate of pheromone per puff from aerosol dispensers is thought to compensate for their low application densities (2-2.5 puffer/hectare). Results of three year field trials carried out in Trentino-South Tyrol demonstrated the potential of Puffer as effective tool to control the moth.

Copper aerosols inhibit phytoplankton growth in the Mediterranean Sea

Aerosol deposition plays an important role in climate and biogeochemical cycles by supplying nutrients to the open ocean, in turn stimulating ocean productivity and carbon sequestration. Aerosol particles also contain elements such as copper (Cu) that are essential in trace amounts for phytoplankton physiology but that can be toxic at high concentrations. Although the toxicity of Cu associated with aerosols has been demonstrated in bioassay experiments, extrapolation of these laboratory results to natural conditions is not straightforward. This study provides observational evidence of the negative effect of aerosols containing high Cu concentrations on marine phytoplankton over a vast region of the western Mediterranean Sea. Direct aerosol measurements were combined with satellite observations, resulting in the detection of significant declines in phytoplankton biomass after atmospheric aerosol events characterized by high Cu concentrations. The declines were more evident during summer, when nanoflagellates predominate in the phytoplankton population and stratification and oligotrophic conditions prevail in the study region. Together with previous findings concerning atmospheric Cu deposition, these results demonstrate that the toxicity of Cu-rich aerosols can involve large areas of the world's oceans. Moreover, they highlight the present vulnerability of oceanic ecosystems to Cu-rich aerosols of anthropogenic origins. Because anthropogenic emissions are increasing, large-scale negative effects on marine ecosystems can be anticipated.

[Effect of 5-fluorouracil aerosol on the growth of human gastric cancer cell line MKN-45 in vitro]

OBJECTIVE

To evaluate the effect of simulated intraperitoneal 5-fluorouracil (5-Fu) aerosol chemotherapy (AIPC) on the proliferation, apoptosis, and cell cycle of human gastric cancer cell line MKN-45 in vitro.

METHODS

The gastric cancer cells MKN-45 were treated with 5-Fu aerosol for 30 min under the pressure of 8 mmHg, and those treated with normal saline (NS) aerosol served as the control. The cell proliferation after the treatment was detected by MTT assay, and flow cytometry and FITC Annexin V/PI kit were used to detect the cell apoptosis and changes in the cell cycle.

RESULTS

MTT assay showed a significantly greater inhibition rate of the cell proliferation in 5-Fu aerosol group than in NS group [(31.13∓3.51)% vs (4.65∓1.99)%, P<0.001]. FCM analysis also showed a significantly higher cell apoptotic rate in 5-Fu aerosol group than in NS group [(12.00∓0.92)% vs (2.65∓0.52)%, P<0.001]. Compared with saline treatment, treatment with 5-Fu aerosol resulted in a greater proportion of G1 phase cells [(51.83∓1.95)% vs (36.41∓2.33)%, P<0.001] with a lowered proportion of S phase cells [(16.72∓2.36)% vs (45.20∓3.27)%, P<0.001].

CONCLUSION

Simulated 5-Fu AIPC can inhibit the proliferation, induce cell apoptosis and cause cell cycle arrest at G1 phase in gastric cancer cells.

Inactivation of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) on various environmental surfaces by mist application of a stabilized chlorine dioxide and quaternary ammonium compound-based disinfectant

Contaminated environmental surfaces are important reservoirs in the transmission of many human pathogens. Although several options exist for disinfecting contaminated environmental surfaces, few are compatible with use on both hard smooth non-porous (hard) and soft porous surfaces (soft) while still offering significant disinfection of the contaminating organisms. This study evaluated the efficacy of mist application of a stabilized chlorine dioxide and quaternary ammonium compound-based disinfectant (Cryocide20) for inactivation of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) on various environmental surfaces. MRSA and VRE were applied to hard and soft surfaces (glass, steel, tile, carpet, and cotton fabric), allowed to dry, and exposed to a uniform mist application of the disinfectant solution. After 1 hr of contact time, the residual disinfectant was neutralized, and the bacteria were recovered and enumerated on brain heart infusion (BHI) agar. Reduction of both test bacteria was observed on most of the hard and soft surfaces tested. Log(10) reduction of the organisms tended to be higher on steel, tile, and carpet than glass or cotton. Overall, these results suggest that mist application of Cryocide20 disinfectant may be an effective option for reduction of low levels of infectious bacterial pathogens from contaminated environmental surfaces.

Efficacy of imidacloprid and fipronil gels over synthetic pyrethroid and propoxur aerosols in control of German cockroaches (Dictyoptera: Blatellidae)

BACKGROUND & OBJECTIVES

Resistance amongst cockroaches has been reported to most of the spray insecticides apart from the problem of food contamination and inconvenience. Gel baits which can be selectively applied have been found effective in control of cockroaches in laboratory studies but very few field studies are available. This trial was planned to evaluate the efficacy of fipronil (0.01%) and imidacloprid (2.15%) gels over synthetic pyrethroid (0.02% deltamethrin + 0.13% allethrin) and propoxur (2%) aerosols in control of cockroaches in the field.

METHODS

Survey was done to find out pre-treatment density in catering establishments and houses by visual count and sticky trap methods. A total of 10 catering establishments and 10 houses having high cockroach infestation were selected by sampling (two catering establishments and houses for each insecticidal treatment and two for control). Propoxur and synthetic pyrethroid aerosols were used for spraying the infested sites once only. Single application of fipronil and imidacloprid gels was used as crack and crevice treatment. Visual count method gave better indications of cockroach infestation as compared to sticky trap method, hence, the same was followed for post-treatment evaluation every week up to 12 weeks.

RESULTS

Synthetic pyrethroid could not bring about the desired reduction in cockroach infestation in the present study. Single application of fipronil gel was able to reduce cockroach infestation up to 96.8% at the end of 12 weeks whereas imidacloprid application resulted in 90.9% reduction and propoxur resulted in 77.5%. However, propoxur was more effective in reducing the cockroach density by first week in comparison to imidacloprid and fipronil gels but its efficacy started declining after 8th week. Difference was found statistically significant by Kruskal-Wallis H-test.

CONCLUSION

The study reports the efficacy of propoxur aerosol, imidacloprid gel and fipronil gel baits for control of cockroaches.

Scanning electron microscopic and X-ray micro analysis on tooth enamel exposed to alkaline agents

The background of this study comprises two clinical cases, where patients exposed to aerosols of an alkaline and surface active cleaning agent developed loss of enamel substance on their teeth, further resulting in loss of teeth and partially destroyed soft tissues. The alkaline cleaning agent consisted of potassium hydroxide and various surfactants. The purpose of this study was to investigate possible changes in morphology and composition in human teeth enamel exposed to alkaline solutions, by means of X-ray micro analysis (XRMA), FTIR-spectroscopic analyses and scanning electron microscopy (SEM). Extracted premolars, exposed to potassium hydroxide solutions and alkaline cleaning solution,were analyzed by means of XRMA and SEM. Enamel powder, exposed to cleaning solution, was analyzed by means of FTIR. The SEM analysis revealed an increased porosity of the enamel surface and partially loss of enamel substance after exposure to alkaline solutions. The XRMA analyses revealed a decrease in carbon concentration while phosphorous and calcium showed no marked changes. The FTIR analyses showed no significant changes in peak heights or peak positions for phosphate, carbonate or hydroxide. It was concluded that human teeth enamel exposed to alkaline solutions showed loss of organic substance, marked pores in enamel surface and loss of substance in the enamel surface.

In vitro mercury exposure on spermatozoa from normospermic individuals

Epidemiological evidence suggests that exposure to industrial metal aerosols is detrimental to the male reproductive system. Oxidative stress has been identified as a crucial factor leading to male factor infertility largely due to peroxidative damage to the sperm cell membrane. The objectives of the present study were to test the effect of mercury in the concentration range from 50 to 800 micromol(-1), in vitro, on the sperm membrane and DNA integrity, motility and acrosomal status of human spermatozoa. We found a significant increase in the Lipo Per Oxidation (LPO) indicating the deleterious effect of mercury on the sperm membrane integrity. This effect was prominent at the concentration of 800 microM mercury. There was also a strong negative correlation between LPO rate and percentage of viable spermatozoa (r = -0.941, p<0.001). Data obtained from SCGE assay technique revealed that mercury is capable of inducing DNA breaks in the sperm nuclei. Almost, 88% of DNA breaks were of double-stranded. The correlation between LPO rate and percentage of DNA breaks was found to be 0.918 (p<0.001). Performing the gelatin digestion test indicates that mercury was able to alter the integrity of acrosomal membranes showing an abnormal acrosome reaction. In this regard, a strong correlation was found between LPO rate and percentage of halos (r = -0.893, p<0.001). Taken together, mercury induced membrane impairments, lowered sperm viability, DNA breaks and a decreased rate in the acrosome reaction of human spermatozoa leading to sperm dysfunction. Entering mercury in the male gonads and seminal plasma may exert deleterious effects on the human spermatozoa. Hence, considering the wide spread use of mercury and its compounds, these metals should regarded with more concern.

Nanotechnology and pharmaceutical inhalation aerosols

Pharmaceutical inhalation aerosols have been playing a crucial role in the health and well being of millions of people throughout the world for many years. The technology's continual advancement, the ease of use and the more desirable pulmonary-rather-than-needle delivery for systemic drugs has increased the attraction for the pharmaceutical aerosol in recent years. But administration of drugs by the pulmonary route is technically challenging because oral deposition can be high, and variations in inhalation technique can affect the quantity of drug delivered to the lungs. Recent advances in nanotechnology, particularly drug delivery field have encouraged formulation scientists to expand their reach in solving tricky problems related to drug delivery. Moreover, application of nanotechnology to aerosol science has opened up a new category of pharmaceutical aerosols (collectively known as nanoenabled-aerosols) with added advantages and effectiveness. In this review, some of the latest approaches of nano-enabled aerosol drug delivery system (including nano-suspension, trojan particles, bioadhesive nanoparticles and smart particle aerosols) that can be employed successfully to overcome problems of conventional aerosol systems have been introduced.

Efficacy of super-oxidized water fogging in environmental decontamination

The efficacy of decontamination using Sterilox fog was assessed against meticillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii. Ceramic tiles were inoculated with the test organisms and, once dried, were subjected to Sterilox fogging using a stationary vaporizing machine sited at a distance of 3m for 10 min and then left for a further hour. In a second experiment using the same organisms, the first 10-min fogging period was followed by a directed fogging period of 30s at a distance of 1m. Organisms were cultured from the tiles, plated on to tryptone soya agar and incubated for 48 h. Initial counts of approximately 10(9) colony-forming units/mL for both organisms were reduced approximately 10(4) fold for MRSA and 10(5.8) fold for A. baumannii when using a single fogging. The second fogging resulted in 10(6.8)-fold reductions for both organisms. Sterilox fog is safe and simple to use, and can reduce levels of nosocomial pathogens by a factor of almost 10(7). It is worthy of clinical evaluation in clinical settings to determine whether it maintains its microbicidal effects against a variety of organisms on different surfaces.

Cutaneous effects of cryogen spray cooling on in vivo human skin

BACKGROUND

Despite widespread clinical use of cryogen spray cooling (CSC) in conjunction with laser dermatologic surgery, in vivo cutaneous effects have not been systematically evaluated.

OBJECTIVE

The authors characterize the in vivo cutaneous effects for Fitzpatrick skin types I through VI after CSC exposures of varying spurt durations and spurt delivery patterns (single vs. multiple spurts).

MATERIALS AND METHODS

Twenty-seven normal human subjects were exposed to single cryogen spurts from 10 to 80 milliseconds, and multiple spurt patterns consisting of two 20-millisecond spurts, four 10-millisecond spurts, and eight 5-millisecond spurts. Subjects were evaluated by clinical observation and photography at 1 hour, 1 day, and 1, 4, 8, and 12 weeks after CSC exposure.

RESULTS

Acute erythema and urticaria (1-24 hours) were noted in 14 of 27 and 3 of 27 subjects, respectively. Transient hyperpigmentation occurred in 4 of 27 subjects (skin types III-VI) but resolved spontaneously without medical intervention in all subjects by 8 weeks. No permanent skin changes were noted in any subjects. Skin reactions were more common with longer single-spurt durations (50 milliseconds or greater) and multiple spurt patterns.

CONCLUSION

Acute erythema, urticaria, and, less commonly, transient hyperpigmentation were observed after CSC exposure. Permanent skin injury was not observed and is unlikely.

Characterization of Regional and Local Deposition of Inhaled Aerosol Drugs in the Respiratory System by Computational Fluid and Particle Dynamics Methods

The present work describes the local deposition patterns of therapeutic aerosols in the oropharyngeal airways, healthy and diseased bronchi and alveoli using computational fluid and particle dynamics techniques. A user-enhanced computational fluid dynamics commercial finite- volume software package was used to compute airflow fields, deposition efficiencies, and deposition patterns of therapeutic aerosols along the airways. Adequate numerical meshes, generated in different airway sections, enabled us to more precisely define trajectories and local deposition patterns of inhaled particles than before. Deposition patterns show a high degree of heterogeneity of deposition along the airways, being more uniform for nanoparticles compared to micro-particles in the whole respiratory system at all inspiratory flow rates. Extrathoracic and tracheobronchial deposition fractions of nanoparticles decrease with increasing flow rates. However, vice versa happens to the micron-size particles, that is, the deposition fraction is higher at high flow rates. Both airway constrictions and the presence of tumors significantly increased the deposition efficiencies compared to the deposition efficiencies in healthy airways by a factor ranging from 1.2 to 4.4. In alveoli, the deposition patterns are strongly influenced by particle size and direction of gravity. This study demonstrated that numerical modeling can be a powerful tool in the aerosol drug delivery optimization. Present results may be integrated in future aerosol drug therapy protocols.

Three-Dimensional Computational Fluid Dynamics Simulations of Particle Deposition in the Tracheobronchial Tree

Simulation of the dynamics and disposition of inhaled particles within human lungs is an invaluable tool in both the development of inhaled pharmacologic drugs and the risk assessment of environmental particulate matter (PM). The goal of the present focused study was to assess the utility of three-dimensional computational fluid dynamics (CFD) models in studying the local deposition patterns of PM in respiratory airways. CFD models were validated using data from published experimental studies in human lung casts. The ability of CFD to appropriately simulate trends in deposition patterns due to changing ventilatory conditions was specifically addressed. CFD simulations of airflow and particle motion were performed in a model of the trachea and main bronchi using Fluent Inc.'s FIDAP CFD software. Particle diameters of 8 microm were considered for input flow rates of 15 and 60 L/min. CFD was able to reproduce the observed spatial heterogeneities of deposition within the modeled bifurcations, and correctly predicted the "hot-spots" of particle deposition on carinal ridges. The CFD methods also predicted observed differences in deposition for high-versus-low flow rates. CFD models may provide an efficient means of studying the complex effects of airway geometry, particle characteristics, and ventilatory parameters on particle deposition and therefore aid in the design of human subject experiments.

Hyperosmolar agents and clearance of mucus in the diseased airway

Clearance of mucus is an important function of the airways to maintain hygiene. In disease, persistent inflammation leads to excessive production of mucus, with high viscoelasticity and adhesivity, which is not easily transported by cilia or cough interactions. Accumulated mucus in the airways can lead to airway obstruction, bacterial colonisation, and recurrent infections, resulting in poor quality of life and increased morbidity and mortality. Hyperosmolar agents have the potential to alter the physical properties of mucus and facilitate its clearance by increasing the water in the airway lumen and by reducing the entanglements of the mucin network. Clinical studies using radioaerosols, and imaging with a gamma camera, have demonstrated that hypertonic saline (HS; 3-14.4%) and mannitol (300-400 mg) increase clearance of mucus acutely in patients with mild asthma, bronchiectasis, and cystic fibrosis (CF). Further, in sputum studies, a reduction in the viscoelastic properties, surface tension and spinnability and an increase in the hydration of mucus have been measured in response to HS, mannitol, and other sugars. Inhalation of mannitol (400 mg) twice daily over 2 weeks improved the quality of life significantly in patients with bronchiectasis. Inhalation of 7% HS, four times daily, over 2 weeks improved significantly the baseline mucus clearance rate and lung function in CF patients. In addition, inhalation of 7% HS twice daily over 12 months showed similar results to the short-term studies without a change in the bacterial load in CF patients. Further studies of the long-term clinical effect of hyperosmolar agents are needed.

Assessment of an aerosol treatment to improve air quality in a swine concentrated animal feeding operation (CAFO)

Poor air quality within swine concentrated animal feeding operations (CAFOs) poses a threat to workers, the surrounding community, and farm production. Accordingly, the current study was conducted to evaluate a technology for reducing air pollution including particulate matter (PM), viable bacteria, and ammonia within such a facility. The technology consists of an acid-oil-alcohol aerosol applied daily. Its effectiveness was evaluated by comparing air quality from before to after treatment and between treated and untreated sides of a barn separated by an impervious partition. On the untreated side, air quality was typical for a swine CAFO, with mean PM2.5 of 0.28 mg/m3 and PM(TOT) of 1.5 mg/m3. The treatment yielded a reduction in PM concentration of 75-90% from before to after treatment. Effectiveness increased with time, application, and particle size (40% reduction for 1 microm and 90% for >10 microm). Airborne bacteria levels (total bacteria, Enterobacteriaceae, and gram-positive cocci) decreased one logarithmic unit after treatment. In contrast, treatment had no effect on ammonia concentrations. These findings demonstrate the effectiveness of an intervention in yielding exposure and emission reductions.

Agonist-mediated airway challenge: cardiopulmonary interactions modulate gas exchange and recovery

Diverse agonists used for airway challenges produce a stereotypic sequence of immediate functional responses (e.g., bronchoconstriction, gas trapping, hypoxemia, etc.) at the time such reactions are triggered. The reaction incorporates both pulmonary and cardiac changes that clearly interact in an orchestrated fashion taking the subject (or animal model) through the response generally to ultimate recovery. We hypothesize that despite differences in the initiation of the response, diverse airway provocations lead to a cascade of events that converge through a common physiologic pathway. To better understand the sequence of events and the counterbalanced cardiopulmonary responses, we examined histamine, methacholine, and ovalbumin (OVA) challenges in the awake guinea pig model and assessed ventilatory and breathing mechanics in the context of associated cardiac parameters. With the histamine response as the prototype, we evaluated the role of beta-adrenoreceptors using propranolol (1.0-10 mg/kg i.p.) and found that beta-adrenoreceptors are critical in reducing challenge-induced gas trapping in the lungs. The disposition of the circulatory response to agonist challenge (the OVA model) was reflected in a significant absolute shunting of blood through poorly ventilated regions of the lung. The methacholine challenge revealed that gasping enhanced lung inflation and reversed the diminished Pa(O2). Moreover, beta-sympathetic function was critical to recovery. Collectively, the response profiles of these disparate models of airway challenge suggest a highly integrated balance to maintain gas exchange among the pulmonary airways and vasculature, modulated in recovery by beta-adrenoreceptors.

Effect of Structural Relaxation on the Physical and Aerosol Properties of Amorphous Form of FK888 (NK1 Antagonist)

FK888 (NK1 antagonist) is a candidate drug for migraine and selected as a model of amorphous drug. FK888 was micronized to develop as dry powder inhalers (DPIs) taking into consideration of its water insoluble property. The glass transition temperature (Tg) and fragility (m) were 90 degrees C and 118, respectively, and it was categorized as a fragile glass based on Angell's concept. FK888 was structurally relaxed by aging below Tg, then the effect of aging on their physical and aerosol properties were investigated. The investigation on the moisture sorption-desorption isotherms of FK888 indicated that aged FK888 adsorbed less amount of water than that of unaged FK888. This unique moisture sorption-desorption behavior of the aged sample is explained by structural relaxation accompanying decrease of free volume and/or increase of density. As for the dissolution rate of unaged and aged FK888, they showed the similar value, suggesting that there would be no difference in bioavailability. In relation to the stability, FK888 DPIs prepared by unaged and aged FK888 were stored at 70 degrees C, and the respirable fraction of FK888 DPIs was evaluated by using multistage cascade impactor (USP apparatus 3). As a result, the respirable fraction of FK888 DPIs prepared by unaged sample was significantly decreased compared to the aged sample, suggesting that agglomeration may occur in the unaged sample during the storage. This phenomenon was supported by that the unaged sample showed a significant decrease in the surface area compared to that of the aged sample when stored at various conditions.

Effects of hypobaric pressure on human skin: Implications for cryogen spray cooling (Part II)

BACKGROUND AND OBJECTIVES

Clinical results have demonstrated that dark purple port wine stain (PWS) birthmarks respond favorably to laser induced photothermolysis after the first three to five treatments. Nevertheless, complete blanching is rarely achieved and the lesions stabilize at a red-pink color. In a feasibility study (Part I), we showed that local hypobaric pressure on PWS human skin prior to laser irradiation induced significant lesion blanching. The objective of the present study (Part II) is to investigate the effects of hypobaric pressures on the efficiency of cryogen spray cooling (CSC), a technique that assists laser therapy of PWS and other dermatoses.

STUDY DESIGN/MATERIALS AND METHODS

Experiments were carried out within a suction cup and vacuum chamber to study the effect of hypobaric pressure on the: (1) interaction of cryogen sprays with human skin; (2) spray atomization; and (3) thermal response of a model skin phantom. A high-speed camera was used to acquire digital images of spray impingement on in vivo human skin and spray cones generated at different hypobaric pressures. Subsequently, liquid cryogen was sprayed onto a skin phantom at atmospheric and 17, 34, 51, and 68 kPa (5, 10, 15, and 20 in Hg) hypobaric pressures. A fast-response temperature sensor measured sub-surface phantom temperature as a function of time. Measurements were used to solve an inverse heat conduction problem to calculate surface temperatures, heat flux, and overall heat extraction at the skin phantom surface.

RESULTS

Under hypobaric pressures, cryogen spurts did not produce skin indentation and only minimal frost formation. Sprays also showed shorter jet lengths and better atomization. Lower minimum surface temperatures and higher overall heat extraction from skin phantoms were reached.

CONCLUSIONS

The combined effects of hypobaric pressure result in more efficient cryogen evaporation that enhances heat extraction and, therefore, improves the epidermal protection provided by CSC.

The effect of fusafungine on post-operative pain and wound healing after pediatric tonsillectomy

OBJECTIVE

To investigate the effect of fusafungine spray on pain and healing process after pediatric tonsillectomy.

METHODS

Sixty children with ages between 4 and 14 years underwent tonsillectomy or adenotonsillectomy. The patients were randomly divided into three groups and each group consisted of 20 patients. Group 1 was treated with antibiotic (amoxicillin-clavulanic acid) plus analgesic (acetaminophen), group 2 was treated with fusafungine plus analgesic (acetaminophen) and group 3 was treated with only fusafungine. The average ages were 7.8 + 3.4, 6.6 + 2.9, and 8.2 + 3.7 for groups 1, 2, and 3, respectively. Clinical evaluations were made after the operation on the 1st (T1), 3rd (T3), 7th (T7), 10th (T10), and 14th days (T14).

RESULTS

There was no significant difference in post-operative pain between study groups on the post-operative 1st, 3rd, and 7th days (P > 0.05), a statistically significant difference was present between groups 1 and 3, and groups 1 and 2 on the post-operative 10th and 14th day (P = 0.018 and 0.037, respectively). Pain was less in groups 2 and 3 than in group 1 on the 10th and 14th day. Also there was a significant difference in healing time of the tonsillary beds between groups 1 and 2, and groups 1 and 3 on the 10th and 14th post-operative day (P = 0.031 and 0.001, respectively). Healing was better in groups 2 and 3 than in group 1 on the 10th and 14th day.

CONCLUSION

Fusafungine administration after tonsillectomy was found to be beneficial on post-operative pain and wound healing of tonsillary beds in pediatric population.

Evaluation of cryogen spray cooling exposure on in vitro model human skin

BACKGROUND AND OBJECTIVES

Cryogen spray cooling (CSC) is commonly used during dermatologic laser surgery. The epidermal and dermal effects of CSC have not been adequately evaluated. To study the potential for epidermal and dermal injury after CSC using an in vitro model of human skin (RAFT).

STUDY DESIGN/MATERIALS AND METHODS

RAFT specimens were exposed to continuous CSC spurt durations of 10, 20, 40, 80, 100, 200, or 500 milliseconds. Biopsies were taken acutely, 3 and 7 days post-CSC exposure. Sections were stained with hematoxylin and eosin for evaluation of possible injury, Ki-67 to determine keratinocyte viability, and Melan-A, to identify and evaluate melanocytes.

RESULTS

Minimal, transient epidermal changes were noted in specimens exposed to continuous CSC spurts of 80 milliseconds or less. Keratinocytes and melanocytes remained viable. Continuous CSC spurts of 100, 200, or 500 milliseconds (much longer than recommended for clinical use) resulted in significant epidermal injury acutely, with partial or full thickness epidermal necrosis at 7 days. Only the 500 milllisecond specimen demonstrated dermal change, decreased fibroblast proliferation at 3 days.

CONCLUSIONS

Continuous CSC spurts of 80 milliseconds or less induce minimal, if any, epidermal or dermal damage and are unlikely to produce cryo-injury when used during dermatologic laser surgery.

Effect of Tubing Deposition, Breathing Pattern, and Temperature on Aerosol Mass Distribution Measured by Cascade Impactor

Aerosols produced by nebulizers are often characterized on the bench using cascade impactors. We studied the effects of connecting tubing, breathing pattern, and temperature on mass-weighted aerodynamic particle size aerosol distributions (APSD) measured by cascade impaction. Our experimental setup consisted of a piston ventilator, low-flow (1.0 L/min) cascade impactor, two commercially available nebulizers that produced large and small particles, and two "T"-shaped tubes called "Tconnector(cascade)" and "Tconnector(nebulizer)" placed above the impactor and the nebulizer, respectively. Radiolabeled normal saline was nebulized using an airtank at 50 PSIG; APSD, mass balance, and Tconnector(cascade) deposition were measured with a gamma camera and radioisotope calibrator. Flow through the circuit was defined by the air tank (standing cloud, 10 L/min) with or without a piston pump, which superimposed a sinusoidal flow on the flow from the air tank (tidal volume and frequency of breathing). Experiments were performed at room temperature and in a cooled environment. With increasing tidal volume and frequency, smaller particles entered the cascade impactor (decreasing MMAD; e.g., Misty-Neb, 4.2 +/- 0.9 microm at lowest ventilation and 2.7 +/- 0.1 microm at highest, p = 0.042). These effects were reduced in magnitude for the nebulizer that produced smaller particles (AeroTech II, MMAD 1.8 +/- 0.1 to 1.3 +/- 0.1 microm; p = 0.0044). Deposition on Tconnector(cascade) increased with ventilation but was independent of cascade impactor flow. Imaging of the Tconnector(cascade) revealed a pattern of deposition unaffected by cascade impactor flow. These measurements suggest that changes in MMAD with ventilation were not artifacts of tubing deposition in the Tconnector(cascade). At lower temperatures, APSD distributions were more polydisperse. Our data suggest that, during patient inhalation, changes in particle distribution occur that are related to conditions in the tubing and may reduce the diameters of particles entering the patient. This effect is more significant for nebulizers producing large particles. Changes in ambient temperature did not affect these observations.