Nose-only Exposure Research Articles

Inhalation Study of Mycobacteriophage D29 Aerosol for Mice by Endotracheal Route and Nose-Only Exposure.

Lytic mycobacteriophage D29 has the potential for tuberculosis treatment including multidrug-resistant strains. The aims of this study are to investigate deposition and distribution of aerosolized phage D29 particles in naive Balb/C mice, together with pharmacokinetics and evaluation of acute lung injury. Pharmacokinetics and BALF (bronchoalveolar lavage fluids) were analyzed after administration of phage D29 aerosols by endotracheal route using Penn-century aerosolizer; Collison 6-jet and Spinning top aerosol nebulizers (STAG) were used to generate phage aerosols with different particle size distributions in nose-only inhalation experiments. After exposure, deposited amounts of phage D29 particles in respiratory tracts were measured, and deposition efficiencies were calculated. A typical path deposition model for mice was developed, and then comparisons were made between predictions and experimentally measured results. Approximately 10% of aerosolized phages D29 reached lung of mouse for pulmonary delivery, and were completely eliminated until 72 h after administration. In contrast, about 0.1% of intraperitoneal injected phages reached the lung, and were almost eliminated at 12 h time point. The inflammation was hardly observed in lung according to the results of BALF analysis. The CMADs (count median aerodynamic diameters) of generated aerosol by Collison and STAG nebulizer were 0.8 μm and 1.5 μm, respectively. After nose-only exposure, measured deposition efficiencies in whole respiratory tract for 0.8 and 1.5 μm phage particles were below 1% and 10%, respectively. Predictions of the computer deposition model compared fairly well with experimentally measured results. This is the first systematic study of phage D29 aerosol respiratory challenge in laboratory animals. It provides evidence that aerosol delivery of phage D29 is an effective way for treating pulmonary infections caused by Mycobacterium tuberculosis. This research will also provide important data for future inhalation experiments.

Design and Characterization of an Inhalation System to Expose Rodents to Nanoaerosols

ABSTRACTThe number of workers potentially exposed to nanoparticles (NPs) in industrial processes is constantly increasing, even though the toxicological effects of these compounds have not yet been fully characterized. The hazards associated with this exposure can be assessed most relevantly by toxicology studies involving inhalation of nanoaerosols by animals. In this paper, we describe and characterize an aerosol generated in a nose-only exposure system used to study the respiratory effects of NPs in rat; this system was designed to meet the most stringent requirements for animal testing in terms of protection of operators against risks associated with NPs and biohazards and to comply with the OECD guidelines for chemical testing. The inhalation facility was fully validated by exposing Fisher 344 rats to TiO2 P25 aerosols at 10 mg m–3. Aerosol monitoring and in-depth characterization were ensured by real-time devices (condensation particle counter, optical particle sizer, scanning mobility particle sizer, aerodynamic particle sizer and electrical low pressure impactor) and samples taken for off-line analyses (gravimetric analysis, mass size distribution from cascade impactor, TEM observations). The test atmosphere was stable in terms of concentrations and distributions (mass or number) between different inhalation towers on a given day and between days (intra-experiment), as well as between inhalation campaigns (between experiments). In terms of the respiratory deposition profile, preliminary results after exposure for one month indicate that this system is relevant, and should therefore be appropriate for in vivo inhalation toxicity studies.

Characterization of a nose-only inhaled phosgene acute lung injury mouse model

Context: Phosgene’s primary mode of action is as a pulmonary irritant characterized by its early latent phase where life-threatening, non-cardiogenic pulmonary edema is typically observed 6‐24 h post-exposure.Objective: To develop an inhaled phosgene acute lung injury (ALI) model in C57BL/6 mice that can be used to screen potential medical countermeasures.Methods: A Cannon style nose-only inhalation exposure tower was used to expose mice to phosgene (8 ppm) or air (sham). An inhalation lethality study was conducted to determine the 8 ppm median lethal exposure (LCt50) at 24 and 48 h post-exposure. The model was then developed at 1.2 times the 24 h LCt50. At predetermined serial sacrifice time points, survivors were euthanized, body and lung weights collected, and lung tissues processed for histopathology. Additionally, post-exposure clinical observations were used to assess quality of life.Results and discussion: The 24-hour LCt50 was 226 ppm*min (8 ppm for 28.2 min) and the 48-hour LCt50 was 215 ppm*min (8 ppm for 26.9 min). The phosgene exposed animals had a distinct progression of clinical signs, histopathological changes and increased lung/body weight ratios. Early indicators of a 1.2 times the 24-hour LCt50 phosgene exposure were significant changes in the lung-to-body weight ratios by 4 h post-exposure. The progression of clinical signs and histopathological changes were important endpoints for characterizing phosgene-induced ALI for future countermeasure studies.Conclusion: An 8 ppm phosgene exposure for 34 min (1.2 × LCt50) is the minimum challenge recommended for evaluating therapeutic interventions. The predicted higher mortality in the phosgene-only controls will help demonstrate efficacy of candidate treatments and increase the probability that a change in survival rate is statistically significant.

Size-dependent deposition of inhaled nanoparticles in the rat respiratory tract using a new nose-only exposure system

ABSTRACTConcerns about the potential health effects of exposure to nanomaterials have led to a growing number of in vivo inhalation toxicity studies using nanoparticle aerosols. Estimates of aerosol deposition within the respiratory tract are important for these studies to enable: (a) the interpretation of the results, in particular, the evaluation of dose–response relationships; (b) comparison with the results of other related studies; and (c) the extrapolation of results from animal models to human. Unfortunately, only a limited number of studies have been undertaken to investigate respiratory tract deposition efficiencies for nano-sized aerosol particles. This is of particular importance as deposition efficiencies are predicted to vary significantly over the nano-size range for some elements of the respiratory tract. In this study, female Wistar-Kyoto rats were exposed in a new design nose-only inhalation exposure system to spark generated radioactive iridium-192 nanoparticle aerosols of four particle ...

Nose-only cigarette smoke exposure plus airway lipopolysaccharide inhalation induced chronic obstructive pulmonary disease and associated pulmonary hypertension in mice

To establish a mouse model of chronic obstructive pulmonary disease (COPD) and associated pulmonary hypertension (COPD-PH) induced by nose-only cigarette smoking exposure plus airway lipopolysaccharide (LPS) inhalation. There were 24 male C57B6 mice divided into a control group and a model group at random. The model group was given LPS by intranasal inhalation on day 1 and day 14 and exposed to the cigarette smoke in a nose-only exposure system, while the control group was given physiological saline and exposed to normal air. The model establishment was evaluated according the following parameters: the lung function and the right heart pressure, the total and differential cell numbers in bronchial alveolar lavage fluid (BALF), and the pathological changes of lung tissues. The functional residual capacity data of the model group and the control group were (0.402 ± 0.057) and (0.243 ± 0.064) ml respectively (P<0.05). The inspiratory resistance data of the model group and the control group were (1.056 ± 0.121) and (0.789 ± 0.063) cmH(2)O · ml(-1) · s(-1) (1 cmH(2)O=0.098 kPa) respectively (P<0.05). The static lung compliance data of the model group and the control group were (0.084 ± 0 .007) and (0.056 ± 0.004) cmH(2)O/ml respectively (P<0.05). The right ventricular mean pressure of the model group and the control group were (11.3 ± 1.3) and (7.9 ± 1.1) mmHg (1 mmHg=0.133 kPa) respectively (P<0.05), while the right ventricular hypertrophy index of the model group and the control group were (0.267 ± 0.019) and (0.195 ± 0.023) respectively (P<0.05). Moreover, the histological staining showed that goblet cell hyperplasia, lung inflammation and thickening of smooth muscle layers of bronchial and pulmonary small vessels occurred in the model group, which indicated ongoing airway and blood vessel remodeling. A COPD-PH mouse model was established by nose-only cigarette smoking exposure plus airway LPS inhalation in a short period of time, and this method was more similar to the smoking behavior of human.

Maternal exposure to diluted diesel engine exhaust alters placental function and induces intergenerational effects in rabbits.

BackgroundAirborne pollution is a rising concern in urban areas. Epidemiological studies in humans and animal experiments using rodent models indicate that gestational exposure to airborne pollution, in particular diesel engine exhaust (DE), reduces birth weight, but effects depend on exposure duration, gestational window and nanoparticle (NP) concentration. Our aim was to evaluate the effects of gestational exposure to diluted DE on feto-placental development in a rabbit model.Pregnant females were exposed to diluted (1 mg/m3), filtered DE (NP diameter ≈ 69 nm) or clean air (controls) for 2 h/day, 5 days/week by nose-only exposure (total exposure: 20 days in a 31-day gestation).ResultsDE exposure induced early signs of growth retardation at mid gestation with decreased head length (p = 0.04) and umbilical pulse (p = 0.018). Near term, fetal head length (p = 0.029) and plasma insulin and IGF1 concentrations (p = 0.05 and p = 0.019) were reduced. Placental function was also affected, with reduced placental efficiency (fetal/placental weight) (p = 0.049), decreased placental blood flow (p = 0.009) and fetal vessel volume (p = 0.002). Non-aggregated and “fingerprint” NP were observed at various locations, in maternal blood space, in trophoblastic cells and in the fetal blood, demonstrating transplacental transfer. Adult female offspring were bred with control males. Although fetoplacental biometry was not affected near term, second generation fetal metabolism was modified by grand-dam exposure with decreased plasma cholesterol (p = 0.008) and increased triglyceride concentrations (p = 0.015).ConclusionsRepeated daily gestational exposure to DE at levels close to urban pollution can affect feto-placental development in the first and second generation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-016-0151-7) contains supplementary material, which is available to authorized users.

In vivo biodistribution and physiologically based pharmacokinetic modeling of inhaled fresh and aged cerium oxide nanoparticles in rats.

BackgroundCerium oxide (CeO2) nanoparticles used as a diesel fuel additive can be emitted into the ambient air leading to human inhalation. Although biological studies have shown CeO2 nanoparticles can cause adverse health effects, the extent of the biodistribution of CeO2 nanoparticles through inhalation has not been well characterized. Furthermore, freshly emitted CeO2 nanoparticles can undergo an aging process by interaction with other ambient airborne pollutants that may influence the biodistribution after inhalation. Therefore, understanding the pharmacokinetic of newly-generated and atmospherically-aged CeO2 nanoparticles is needed to assess the risks to human health.MethodsA novel experimental system was designed to integrate the generation, aging, and inhalation exposure of Sprague Dawley rats to combustion-generated CeO2 nanoparticles (25 and 90 nm bimodal distribution). Aging was done in a chamber representing typical ambient urban air conditions with UV lights. Following a single 4-hour nose-only exposure to freshly emitted or aged CeO2 for 15 min, 24 h, and 7 days, ICP-MS detection of Ce in the blood, lungs, gastrointestinal tract, liver, spleen, kidneys, heart, brain, olfactory bulb, urine, and feces were analyzed with a mass balance approach to gain an overarching understanding of the distribution. A physiologically based pharmacokinetic (PBPK) model that includes mucociliary clearance, phagocytosis, and entry into the systemic circulation by alveolar wall penetration was developed to predict the biodistribution kinetic of the inhaled CeO2 nanoparticles.ResultsCerium was predominantly recovered in the lungs and feces, with extrapulmonary organs contributing less than 4 % to the recovery rate at 24 h post exposure. No significant differences in biodistribution patterns were found between fresh and aged CeO2 nanoparticles. The PBPK model predicted the biodistribution well and identified phagocytizing cells in the pulmonary region accountable for most of the nanoparticles not eliminated by feces.ConclusionsThe biodistribution of fresh and aged CeO2 nanoparticles followed the same patterns, with the highest amounts recovered in the feces and lungs. The slow decrease of nanoparticle concentrations in the lungs can be explained by clearance to the gastrointestinal tract and then to the feces. The PBPK model successfully predicted the kinetic of CeO2 nanoparticles in various organs measured in this study and suggested most of the nanoparticles were captured by phagocytizing cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-016-0156-2) contains supplementary material, which is available to authorized users.

Comparison between whole-body inhalation and nose-only inhalation on the deposition and health effects of nanoparticles.

We performed the two inhalation exposures, whole-body inhalation and nose-only inhalation, to investigate the pulmonary deposition and health effects of the two inhalation methods. In both methods, we exposed rats to the same TiO2 nanoparticles at almost the same exposure concentration for 6 h and compared the deposited amounts of nanoparticles and histopathological changes in the lungs. Rats were exposed to rutile-type TiO2 nanoparticles generated by the spray-dry method for 6 h. The exposure concentration in the whole-body chamber was 4.10 ± 1.07 mg/m(3), and that in nose-only chamber was 4.01 ± 1.11 mg/m(3). The particle sizes were 230 and 180 nm, respectively. A control group was exposed to fresh air. The amounts of TiO2 deposited in the lungs as measured by ICP-AES after acid digestion just after the exposure were: 42.6 ± 3.5 μg in the whole-body exposure and 46.0 ± 7.7 μg in the nose-only exposure groups. The histopathological evaluation was the same in both exposure groups: no infiltration of inflammatory cells in the alveolar space and interstitium, and no fibrosis. The two inhalation methods using the same material under the same exposure conditions resulted in the same particle deposition and histopathology in the lung.

Toxicity Evaluation of Exposure to an Atmospheric Mixture of Polychlorinated Biphenyls by Nose-Only and Whole-Body Inhalation Regimens.

The health risk of inhalation exposure to polychlorinated biphenyls (PCB) cannot be assessed with high confidence due to the lack of rigorous inhalation studies. One uncertainty rests on exposure regimen, as whole-body exposure systems allow oral PCB intake that confounds the exposure. We conducted contemporaneous PCB inhalation exposures with whole-body and nose-only exposure methods. Female Sprague-Dawley rats were concurrently exposed to vapor-phase PCBs (533 ± 93 μg/m(3)) generated from PCB11-supplemented Chicago Air Mixture resembling the Chicago airshed, 4 h/day, 6 days/week, for 4 weeks. Congener-specific analysis showed 1.5-fold higher ∑PCBs in the lungs of nose-only exposed than the whole-body exposed animals (p = 0.0024). Higher ∑PCB concentrations were also found in the sera, livers, brains, and adipose tissue of nose-only exposed animals (1.1-1.5-fold), but these increases were not statistically significant. Congener profiles of five tissue types were dominated by PCB 28/31 and higher-chlorinated congeners in both groups reflecting rapid metabolism of other lower-chlorinated PCBs. No toxicity was seen regarding metabolic enzyme expression, glutathione, or histopathology. However, diminished weight gain and reduced plasma total thyroxine levels were found in both groups compared with controls, after exposure to 76 μg/m(3) ∑PCBs as adjusted for continuous exposure. Hepatic lipid peroxidation was also elevated in the nose-only group. Our study shows that prolonged nose-only exposure was well-tolerated and eliminated the need for housing animals outside the vivarium, thus was preferred for long-term PCB inhalation studies.

Lung inflammation and lack of genotoxicity in the comet and micronucleus assays of industrial multiwalled carbon nanotubes Graphistrength(©) C100 after a 90-day nose-only inhalation exposure of rats.

BackgroundGraphistrength© C100 multiwalled carbon nanotubes (MWCNT) provide superior electrical and mechanical properties for various applications. The evaluation of the intrinsic hazard properties of Graphistrength© C100 is an essential step for safe use. A general feature of multiwalled carbon nanotubes after inhalation or intratracheal exposures is the induction of an inflammatory reaction in the lungs sometimes associated with local genotoxic effects.MethodsAfter investigating different parameters for the aerosol generation and performing a 5-day inhalation range finding study, male and female Wistar rats were exposed nose-only for 90 days to target concentrations of 0.05, 0.25 and 5.0 mg/m3 air of Graphistrength© C100 and sacrificed 24 h and 90 days after the last exposure. Broncho-alveolar lavage fluid (BALF) was also collected and analyzed for inflammatory parameters. Twenty-four hours post-exposure, chromosomal aberrations in the bone marrow cells were evaluated by the micronucleus test and DNA damages in the lung, kidney and liver cells by both the standard and the human 8-oxoguanine DNA N-glycosylase 1 (hOGG1)-modified comet assay. All studies were performed according to the OECD test guidelines.ResultsAn inflammatory lung reaction and the release of inflammatory factors in the BALF were observed in all rats exposed to 5.0 mg/m3, associated with changes in the differential white blood cells counts. The slight changes in BALF parameters at 0.25 mg/m3 recovered and signs of lung clearance of the MWCNT were observed. No pathological changes were observed on the pleura. Neither increase in the number of micronucleated polychromatic erythrocytes nor increase in percent DNA damage were observed at any concentration.ConclusionsLung inflammation characteristic of an overload with insoluble particles was observed after a 90-day exposure to 5.0 mg/m3 of Graphistrength© C100. Clear signs of clearance and recovery were observed at 0.25 mg/m3. No genotoxicity was detected locally in lung and distally in bone marrow, liver and kidney. Therefore, Graphistrength© C100 appears of low concern in term of local and systemic genotoxicity and a No-Observed Adverse Effect Concentration (NOAEC) of 0.25 mg/m3 (0.28 mg/m3 as actual concentration) was established for the repeated-dose toxicity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-015-0096-2) contains supplementary material, which is available to authorized users.

Short- and long-term neurobehavioral toxicity of fluorene after a nose-only exposure during the lactating period (14 days) in F1 Wistar rats

Fluorene is a highly volatile polycyclic aromatic compound (PAH) being one of the most abundant in air. Because significant fluorene concentrations have been measured in the breast milk of non-smoking women, the risk for the developing brain of a breast-feeding exposure to this compound was evaluated. Wistar female rats were nose-only exposed to 1.5 or 150 ppb of fluorene from postnatal day 3 (PND3) to PND16 (6h/day, 14 days) whereas the controls were inhaled with clean air over the same period. Rat pups were assessed for their sensory-motor development during the first three weeks of life and for anxiety (elevated-plus maze, EPM), activity (open-field) and spatial learning (Y maze, eight-arm maze) at adulthood. Transient delays in the maturation of motor and sensory abilities of fluorene-exposed pups were observed during the first 3 weeks of life compared to controls at both levels of exposure (1.5 and 150 ppb) whereas the dam behavior towards the pups was exacerbated. At the adult stage, persistent behavioral disturbances related to locomotor activity and anxiety were observed in fluorene-exposed rats whereas their learning abilities remained unaffected. Rats inhaled with 150 ppb of fluorene exhibited a lower anxiety level and a concomitant hyperactivity whereas the opposite was observed in animals exposed to 1.5 ppb. These results show the same behavioral defects as those reported in adult rats inhaled with fluorene (Peiffer et al., PlosOne, 2013) and confirm the potential neurotoxicity of this highly volatile PAH when exposure occurs during the early period of brain development. (max. 250 words)

Strain differences in antioxidants in rat models of cardiovascular disease exposed to ozone

We examined the hypothesis that antioxidant substances and enzymes in lung, heart and in bronchoalveolar lavage fluid (BALF) are altered in response to O3 in cardiovascular disease and/or metabolic syndrome (CVD)-prone rat models. CVD strains [spontaneously hypertensive (SH), SH stroke-prone (SHSP), SHHF/Mcc heart failure obese (SHHF), insulin-resistant JCR:LA-cp obese (JCR) and Fawn-Hooded hypertensive (FHH)] were compared with normal strains [Wistar, Sprague–Dawley (SD) and Wistar Kyoto (WKY)]. Total glutathione (GSH + GSSG or GSx), reduced ascorbate (AH2), uric acid (UA) and antioxidant enzymes were determined in lung, heart and BALF immediately (0 h) or 20-h post 4-h nose-only exposure to 0.0, 0.25, 0.5 and 1.0 ppm O3. Basal- and O3-induced antioxidant substances in tissues varied widely among strains. Wistar rats had a robust O3-induced increase in GSx and AH2 in the lung. Two CVD strains (JCR and SHHF) had high basal levels of AH2 and GSx in BALF as well as high basal lung UA. Across all strains, high BALF GSx was only observed when high BALF AH2 was present. CVD rats tended to respond less to O3 than normal. High-basal BALF AH2 levels were associated with decreased O3 toxicity. In summary, large differences were observed between both normal and CVD rat strains in low-molecular weight antioxidant concentrations in lung, BALF and heart tissue. Wistar (normal) and JCR and SHHF (CVD) rats appeared to stand out as peculiar in terms of basal- or O3-induced changes. Results elucidate interactions among antioxidants and air pollutants that could enhance understanding of cardiopulmonary disease.

Early pulmonary events of nose-only water pipe (shisha) smoking exposure in mice.

Water pipe smoking (WPS) is increasing in popularity and prevalence worldwide. Convincing data suggest that the toxicants in WPS are similar to that of cigarette smoke. However, the underlying pathophysiologic mechanisms related to the early pulmonary events of WPS exposure are not understood. Here, we evaluated the early pulmonary events of nose-only exposure to mainstream WPS generated by commercially available honey flavored “moasel” tobacco. BALB/c mice were exposed to WPS 30 min/day for 5 days. Control mice were exposed using the same protocol to atmospheric air only. We measured airway resistance using forced oscillation technique, and pulmonary inflammation was evaluated histopathologically and by biochemical analysis of bronchoalveolar lavage (BAL) fluid and lung tissue. Lung oxidative stress was evaluated biochemically by measuring the level of reactive oxygen species (ROS), lipid peroxidation (LPO), reduced glutathione (GSH), catalase, and superoxide dismutase (SOD). Mice exposed to WPS showed a significant increase in the number of neutrophils (P < 0.05) and lymphocytes (P < 0.001). Moreover, total protein (P < 0.05), lactate dehydrogenase (P < 0.005), and endothelin (P < 0.05) levels were augmented in bronchoalveolar lavage fluid. Tumor necrosis factor α (P < 0.005) and interleukin 6 (P < 0.05) concentrations were significantly increased in lung following the exposure to WPS. Both ROS (P < 0.05) and LPO (P < 0.005) in lung tissue were significantly increased, whereas the level and activity of antioxidants including GSH (P < 0.0001), catalase (P < 0.005), and SOD (P < 0.0001) were significantly decreased after WPS exposure, indicating the occurrence of oxidative stress. In contrast, airway resistance was not increased in WPS exposure. We conclude that subacute, nose-only exposure to WPS causes lung inflammation and oxidative stress without affecting pulmonary function suggesting that inflammation and oxidative stress are early markers of WPS exposure that precede airway dysfunction. Our data provide information on the initial steps involved in the respiratory effects of WPS, which constitute the underlying causal chain of reactions leading to the long-term effects of WPS.

Polyhexamethylene guanidine phosphate aerosol particles induce pulmonary inflammatory and fibrotic responses.

Polyhexamethylene guanidine (PHMG) phosphate was used as a disinfectant for the prevention of microorganism growth in humidifiers, without recognizing that a change of exposure route might cause significant health effects. Epidemiological studies reported that the use of humidifier disinfectant containing PHMG-phosphate can provoke pulmonary fibrosis. However, the pulmonary toxicity of PHMG-phosphate aerosol particles is unknown yet. This study aimed to elucidate the toxicological relationship between PHMG-phosphate aerosol particles and pulmonary fibrosis. An in vivo nose-only exposure system and an in vitro air-liquid interface (ALI) co-culture model were applied to confirm whether PHMG-phosphate induces inflammatory and fibrotic responses in the respiratory tract. Seven-week-old male Sprague-Dawley rats were exposed to PHMG-phosphate aerosol particles for 3 weeks and recovered for 3 weeks in a nose-only exposure chamber. In addition, three human lung cells (Calu-3, differentiated THP-1 and HMC-1 cells) were cultured at ALI condition for 12 days and were treated with PHMG-phosphate at set concentrations and times. The reactive oxygen species (ROS) generation, airway barrier injuries and inflammatory and fibrotic responses were evaluated in vivo and in vitro. The rats exposed to PHMG-phosphate aerosol particles in nanometer size showed pulmonary inflammation and fibrosis including inflammatory cytokines and fibronectin mRNA increase, as well as histopathological changes. In addition, PHMG-phosphate triggered the ROS generation, airway barrier injuries and inflammatory responses in a bronchial ALI co-culture model. Those results demonstrated that PHMG-phosphate aerosol particles cause pulmonary inflammatory and fibrotic responses. All features of fibrogenesis by PHMG-phosphate aerosol particles closely resembled the pathology of fibrosis that was reported in epidemiological studies. Finally, we expected that PHMG-phosphate infiltrated into the lungs in the form of aerosol particles would induce an airway barrier injury via ROS, release fibrotic inflammatory cytokines, and trigger a wound-healing response, leading to pulmonary fibrosis. A simultaneous state of tissue destruction and inflammation caused by PHMG-phosphate had whipped up a "perfect storm" in the respiratory tract.

Influence of particle size on persistence and clearance of aerosolized silver nanoparticles in the rat lung.

The growing use of silver nanoparticles (AgNPs) in consumer products raises concerns about potential health effects. This study investigated the persistence and clearance of 2 different size AgNPs (20 and 110 nm) delivered to rats by single nose-only aerosol exposures (6 h) of 7.2 and 5.4 mg/m(3), respectively. Rat lung tissue was assessed for silver accumulations using inductively-coupled plasma mass spectrometry (ICP-MS), autometallography, and enhanced dark field microscopy. Involvement of tissue macrophages was assessed by scoring of silver staining in bronchoalveolar lavage fluid (BALF). Silver was abundant in most macrophages at 1 day post-exposure. The group exposed to 20 nm AgNP had the greatest number of silver positive BALF macrophages at 56 days post-exposure. While there was a significant decrease in the amount of silver in lung tissue at 56 days post-exposure compared with 1 day following exposure, at least 33% of the initial delivered dose was still present for both AgNPs. Regardless of particle size, silver was predominantly localized within the terminal bronchial/alveolar duct junction region of the lung associated with extracellular matrix and within epithelial cells. Inhalation of both 20 and 110 nm AgNPs resulted in a persistence of silver in the lung at 56 days post-exposure and local deposition as well as accumulation of silver at the terminal bronchiole alveolar duct junction. Further the smaller particles, 20 nm AgNP, produced a greater silver burden in BALF macrophages as well as greater persistence of silver positive macrophages at later timepoints (21 and 56 days).

Short-term pulmonary effects of nose-only water pipe (shisha) smoking exposure in mice

Introduction: Water pipe smoking (WPS) is a major type of smoking in Middle Eastern countries, and is increasing in popularity in Western countries. It is perceived as relatively safe; however, the underlying pathophysiological mechanisms related to the short-term pulmonary effects of WPS exposure are not understood. Objectives: The aim of this study was to investigate the short-term pulmonary effects of nose-only exposure to mainstream WPS generated by commercially available honey-flavoured tobacco. Materials and methods: BALB/c mice were exposed to WPS for 30 minutes/day for 5 days. Control mice were exposed to atmospheric air only. We measured airway resistance using forced oscillation technique, and pulmonary inflammation was evaluated histopathologically and by biochemical analysis of bronchoalveolar lavage (BAL) fluid and lung tissue. Lung oxidative stress was evaluated biochemically by measuring the level of reactive oxygen species (ROS), reduced glutathione (GSH), catalase and superoxide dismutase (SOD). Results: Mice exposed to WPS showed a significant increase in the number of neutrophils and lymphocytes. Moreover, total protein, lactate dehydrogenase and endothelin levels were augmented in BAL fluid. Tumour necrosis factor α and interleukin 6 concentrations were significantly increased in lung following exposure to WPS. ROS in lung tissue was significantly increased whereas the level and activity of antioxidants, including GSH, catalase and SOD, were significantly decreased after WPS exposure, indicating oxidative stress. By contrast, airway resistance was not increased in WPS exposure. Conclusion: Our data indicate that short-term, nose-only exposure to WPS causes lung inflammation and oxidative stress without affecting pulmonary function. These data provide information on the initial steps involved in the respiratory effects of WPS, which constitute the underlying causal chain of reactions leading to the long-term effects of WPS. Acknowledgements: Professor Abderrahim Nemmar for supervising this project.

Short-Term Nose-Only Water-Pipe (Shisha) Smoking Exposure Accelerates Coagulation and Causes Cardiac Inflammation and Oxidative Stress in Mice

Background/Aim: Water-pipe smoking (WPS) has acquired worldwide popularity, and is disseminating particularly rapidly in Europe and North America. However, little is known about the short-term cardiovascular effects of WPS. Methods: Presently, we assessed the short-term cardiovascular effects of nose-only exposure to mainstream WPS in BALB/c mice for 30 min/day for 5 consecutive days. Control mice were exposed to air. At the end of the exposure period, several cardiovascular endpoints were measured. Results: WPS did not affect the number of leukocytes and the plasma concentrations of C-reactive protein, tumor necrosis factor α (TNFα) and interleukin-6 (IL-6). Likewise, plasma levels of lipid peroxidation (LPO), reduced glutathione (GSH) and catalase were not affected by WPS. By contrast, WPS aggravated in vivo thrombosis by shortening the thrombotic occlusion time in pial arterioles and venules. The number of circulating platelets was reduced by WPS suggesting the occurrence of platelet aggregation in vivo. Elevated concentrations of fibrinogen and plasminogen activator inhibitor-1 were seen after the exposure to WPS. Blood samples taken from mice exposed to WPS and exposed to adenosine diphosphate showed more platelet aggregation. The heart concentrations of IL-6 and TNFα were augmented by WPS. Likewise, heart levels of LPO, reactive oxygen species and the antioxidants catalase and GSH were increased by WPS. However, the systolic blood pressure and heart rate were not affected by WPS. Conclusion: It can be concluded that short-term exposure to WPS exerts procoagulatory effects and induce cardiac inflammation and oxidative stress. At the time point investigated, there was no evidence for blood inflammation or oxidative stress.

Reproductive Toxicity to Male Mice of Nose Only Exposure to Water- Pipe Smoke

Background/Aims: Water-pipe smoking (WPS) is popular in the Middle East and is starting to gain popularity in several Western countries as well. It is widely and erroneously perceived to be less harmful than other forms of tobacco use. The reproductive adverse effects of cigarette smoking have been studied before with conflicting results, but data on the possible adverse reproductive effects of WPS are lacking. Here, we assessed the effects of nose-only exposure to mainstream WPS generated by commercially available honey-flavored "moasel" tobacco in mice. Methods: The duration of the session was 30 min/day for one month. Control mice were exposed to air. Twenty- four h after the last exposure, mice were killed and the testes and plasma removed for analysis. In testicular homogenates total protein, alkaline phosphatase activity, several indices of oxidative damage and Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) were quantified. The plasma concentrations of leptin, testosterone, estrogen and luteinizing hormone (LH) were also measured. Histological analysis of testes and lungs was also conducted. Results: WPS caused statistically significant decreases in the plasma concentrations of leptin, testosterone, and LH, and in the concentrations of total protein and the antioxidant indices measured. A statistically non - significant decrease in VEGFR2 protein in the WPS - exposed mice compared to the control mice was also found. The body and testicular weights of mice exposed to WPS, as well as their testicular alkaline phosphatase activity and light microscopic histology, and plasma estrogen concentration were all not significantly affected by WPS. Conclusion: Further studies on the functional implications of these findings in mice exposed to WPS for longer durations are warranted.

A dynamic smoke generation and nose-only inhalation exposure system for rats: preliminary results from studies of selected transportation materials

Context: Smoke inhalation injury is the main cause of fatalities for fire victims. Understanding in the pathophysiology of the injury has not been fully explored in recent years. To further explore the pathophysiological mechanism, a dynamic and controllable animal model is necessary.Objective: To develop a rat model of smoke inhalation injury to simulate human victims in air-restricted vehicle cabin fires.Materials and methods: Smoke concentration, including CO, O2, VOCs and smoke temperature under different combustion conditions, were detected. Levels of COHb, respiratory function, lung wet-to-dry weight ratio and protein concentration in BALF and blood were measured. Pathological evaluations of lung in tissues were conducted at 1, 6, 24 and 48 h post-exposure.Results: Smoke concentration rose with the increase of combustion temperature and decrease of oxygen flow. Further, 215 kinds of VOCs in the smoke were detected, and the concentrations of benzene, methylbenzene, ethylbenzene, dimethylbenzene, phenylethylene and trimethylbenzene was 32.93, 402.06, 764.03, 113.73, 1006.61 and 89.28 mg/m3, respectively. Significant hypoxemia and CO poisoning occurred in rats. The FCOHb after exposure for 14 min immediately rose to (44.2 ± 12.3) % and then gradually decrease to a normal level at 300 min post-exposure. At 24 h post-exposure, Penh increased significantly (p < 0.05), and high pulmonary vascular permeability and significant lung edema (p < 0.05) were observed in the smoke inhalation group.Discussion and conclusion: In summary, the novel rat model of smoke inhalation injury system used in the study is dynamic and controllable, and appropriate for use in smoke inhalation injury studies of air-restricted cabins in vehicles.

Antenatal exposure of maternal secondhand smoke (SHS) increases fetal lung expression of RAGE and induces RAGE-mediated pulmonary inflammation.

BackgroundReceptors for advanced glycation end-products (RAGE) are immunoglobulin-like pattern recognition receptors abundantly localized to lung epithelium. Our research demonstrated that primary tobacco smoke exposure increases RAGE expression and that RAGE partly mediates pro-inflammatory signaling during exposure. However, the degree to which RAGE influences developing lungs when gestating mice are exposed to secondhand smoke (SHS) has not been determined to date.MethodsTimed pregnant RAGE null and wild type control mice were exposed to 4 consecutive days of SHS from embryonic day (E) 14.5 through E18.5 using a state of the art nose-only smoke exposure system (Scireq, Montreal, Canada). RAGE expression was assessed using immunofluorescence, immunoblotting, and quantitative RT-PCR. TUNEL immunostaining and blotting for caspase-3 were performed to evaluate effects on cell turnover. Matrix abnormalities were discerned by quantifying collagen IV and MMP-9, a matrix metalloprotease capable of degrading basement membranes. Lastly, TNF-α and IL-1β levels were assessed in order to determine inflammatory status in the developing lung.ResultsPulmonary RAGE expression was elevated in both dams exposed to SHS and in fetuses gestating within mothers exposed to SHS. Fetal weight, a measure of organismal health, was decreased in SHS-exposed pups, but unchanged in SHS-exposed RAGE null mice. TUNEL assessments suggested a shift toward pulmonary cell apoptosis and matrix in SHS-exposed pups was diminished as revealed by decreased collagen IV and increased MMP-9 expression. Furthermore, SHS-exposed RAGE null mice expressed less TNF-α and IL-1β when compared to SHS-exposed controls.ConclusionsRAGE augmentation in developing pups exposed to maternal SHS weakens matrix deposition and influences lung inflammation.