Aerosol Inhalation Research Articles

EFFECT OF ALUMINIUM FLUORIDE ON LIVER FUNCTIONS OF RATTUSNORVEGICUS AFTER AMELIORATION BY MORINGA OLEIFERA

Animals and humans are frequently exposed to aluminium and fluoride, and poisoning can occur. Ingestion of aluminium-fluoride occurs primarily through inhalation of aerosols or particles, food, water and medication. This study addresses the serious effects of aluminum fluoride on liver function in albino rats (SGPT, SGOT and ALP) and their amelioration by Moringa oleifera. In this study, we selected 150 healthy adult male albino rats of almost same size and weight ((120 ± 25 gm) and eight weeks old)(because they have the same physiology as humans) and divided them into three groups (control group, treated-I with ALF and treated-II (ALF + Moringa). Rats were maintained on the diet selected according to diagnosis. According to the experimental protocol, rats were exposed to aluminum fluoride and Moringa. Biochemical studies of blood were performed according to standard methods and procedures. Significant changes in liver function (SGOT, SGPT and ALP) were observed in this study. The results showed that excessive aluminum fluoride intake worsened liver function, possibly due to the toxicity of aluminum fluoride. Aluminum fluoride induced liver dysfunction is mediated by increased oxidative stress in rats. Aluminum fluoride has a negative effect on blood sugar in albino rats. However, by including moringa in the treatment of albino rat, the negative effects of fluoride are reduced due to its healing effects. Keywords: Aluminium, Fluoride, Moringa oleifera, Albino Rat, SGPT, SGOT, ALP.

Deposition of secondary organic aerosol in human lung model: Effect of photochemically aged aerosol on human respiratory system

Ultrafine particles (UFP) of Secondary Organic Aerosol (SOA) penetrate deep into the human respiratory system and exert fatal effects on human health. However, there is little data on the potential deposited doses of UFP-generated SOA in the human respiratory tract. This study is to estimate the fraction of aerosol deposition using a multiple-path-particle-dosimetry (MPPD) model. For relevancy of real life, the model employed measured concentrations of toluene-derived fresh and aged SOA produced within serially connected smog chamber and PAM-OFR (Potential Aerosol Mass-Oxidation Flow Reactor) under atmospheric environmental conditions (NOx and relative humidity). The number concentrations and chemical composition of fresh and aged aerosols produced within the chambers were measured using Scanning Mobility Particle Sizer (SMPS) and High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), while the morphology of individual particles was analyzed using Scanning Electron Microscopy (SEM). The number concentration of aged SOA-w/s was more than double compared to that of fresh SOA-w/s (maximum reached after 10 h) with its size less than 100 nm. The O:C ratio for aged SOA-w/s were 0.96 and 1.15 depending on RH (0.96 at 3% RH and 1.15 at 50% RH), and individual spherical particles containing water were present in agglomerates with its size of less than 1 µm. In all inhalable fresh and aged SOA produced in the two chambers, 5–22% of aerosol is deposited in the Head airways, 4–8% in the tracheobronchial, and 8–34% in the alveolar regions. The predominant deposition of the aged aerosol occurred in the alveoli (in the generation 20th lobe), and the deposition faction in the alveoli was 2–3 times higher in the children group than the adults group. This study presented a quantitative exposure assessment of SOA generated under a realistic simulation and suggested the possibility of evaluating long-term exposure to SOA and potential health effects by determining the potential inhalable aerosol doses and the fraction of deposition in the human respiratory system.

Assessment of working conditions and health conditions of employees of non-ferrous metallurgy enterprises

The production conditions of non-ferrous metallurgy enterprises can be characterized by a high severity of the labor process due to excessive physical exertion, constant exposure to intense noise, increased vibration levels; inhalation of industrial aerosols, dust and chemicals; exposure to unfavorable industrial microclimate. The most common types of professionally conditioned and occupational pathology in employees of non-ferrous metallurgy departments are sensorineural hearing loss, vibration disease, radiculopathy, lung and upper respiratory tract diseases, diseases of the musculoskeletal system.
 In order to summarize the information and identify the peculiarities of working conditions and health status of employees of non-ferrous metallurgy enterprises, the researchers analyzed the relevant scientific literature on the bibliographic databases Scopus, Web of Science, MedLine and RSCI using theoretical methods of scientific cognition.
 The most intense impact of production factors is characterized by the working conditions of workers of underground divisions of non-ferrous metallurgy enterprises.
 At the same time, the presence of a specific chemical factor associated with exposure to dust and gas mixtures and aerosols of non-ferrous metals causes the development of morbidity in workers of metallurgical industries for processing and enriching raw materials of non-ferrous metals with toxic alveolitis, bronchial asthma, malignant neoplasms, diseases of the skin and subcutaneous tissue, blood and central nervous system. In this regard, at non-ferrous metallurgy enterprises, when planning a set of preventive measures, the identification of groups of diseases associated with working conditions and caused by the presence of a specific chemical factor of exposure to dust and gas mixtures and aerosols of non-ferrous metals should be considered a necessary condition for preserving the health of workers.
 Ethics. This study did not require the conclusion of the ethics committee.

Neurobehavioral damage and Th17 cell infiltration in mice exposed to nano carbon black

The effects of nano-carbon black on neural behavior and Th17 cell infiltration in mice were investigated by establishing a mice model of subacute dynamic inhalation of carbon black aerosol. 36 SPF grade male C57BL/6 mice were randomly divided into a control group(clean air), a low carbon black group(15 mg/m~3), and a high carbon black group(30 mg/m~3). Nano-carbon black particles were blown into the dynamic exposure cabinet by aerosol generator for 28 days. Morris water maze test and open field test were used to detect the neural behavior of mice. The pathological changes of prefrontal cortex in mice were observed by HE staining. The proportion of Th17/CD4~+ cells in peripheral blood and brain tissue of mice was detected by flow cytometry. Western blotting was used to detect the protein expression of interleukin(IL)-17 and IL-23 in the prefrontal cortex of mice. The result of open field test showed that compared with the control group, the central area residence time and standing times of mice in the low and high carbon black groups decreased significantly(P<0.05), and the defecation times of mice in the high carbon black group increased significantly(P<0.05). The central area residence time of mice in the high carbon black group was significantly lower than that in the low carbon black group(P<0.05). The Morris water maze result showed that the escape latency of the high carbon black group mice on the 3rd day was significantly higher than that of the control group(P<0.05). Meanwhile, the escape latency of the carbon black group mice on the 4th day was significantly higher than that of the control group(P<0.05). The positioning navigation test showed that the number of mice crossing the platform in the high carbon black group was significantly higher than that in the control group(P<0.05). The HE staining result showed that the neural cells in the prefrontal cortex of the control group mice were round, the cytoplasm was plump and evenly distributed, and the nucleus was clearly visible in an oval shape. The low carbon black group showed that the neural cells were deep staining of nerve cells, blurred structure, and nuclear pyknosis. The high carbon black group further intensified. The flow cytometry result showed that compared with the control group, the percentage of Th17/CD4~+T cells in the peripheral blood of the carbon black group mice was significantly increased, and the high carbon black group mice were significantly higher than the low carbon black group(P<0.05). Meanwhile, the percentage of Th17/CD4~+T cells in the brain tissue of carbon black treated mice significantly increased(P<0.05). The high carbon black group was significantly higher than the low carbon black group(P<0.05). Western blotting result showed that compared with the control group, the expression of IL-17 and IL-23 proteins in the prefrontal cortex of the carbon black group mice brain tissue was significantly increased(P<0.05). Compared with the low carbon black group, the expression of IL-17 and IL-23 proteins in the prefrontal cortex of the high carbon black group mice brain tissue was significantly increased(P<0.05). The difference was statistically significant. Nano-carbon black exposure can lead to an increase in Th17 cells in peripheral blood and brain tissue of mice, which in turn promotes damage to the prefrontal cortex of mice, and ultimately causes neurobehavioral changes in mice.

A pediatric case of Chlamydia psittaci caused severe Acute Respiratory Distress Syndrome (ARDS) in Italy

BackgroundThis case of psittacosis in children, is the first described in literature, in Italy. This respiratory infection can be transmitted to humans from the inhalation of respiratory secretions, feces and plumage aerosol of infected birds (and other animals). Usually it can have an asymptomatic or paucisymptomatic course, and the onset is often flu-like, but in this case the child risked his life for a severe respiratory failure. This report is unique because in children psittacosis is rare, and always misdiagnosed, or could cause a delayed diagnosis because of lack of awareness among the paediatricians and physicians. Furthermore, psittacosis enters a differential diagnosis with SARS-COV2 infection because both diseases may determine dyspnea and atypical pneumonia, up to acute respiratory failure.Case presentationThis clinical case talks about a three-and-a-half-year-old male child affected by psittacosis (or ornithosis), with severe dyspnea and systemic symptoms who required oro-tracheal intubation for acute respiratory failure. The child had slept in a room at home, with some recently bought parrots affected by psittacosis. Initially the child was treated with empiric antibiotic therapy (i.v.ceftriaxone and teicoplanin), but after having isolated the DNA of the germ “Chlamydia psittaci” in both serological and through bronchoalveolar lavage (BAL), he was treated with targeted antibiotic therapy: tetracyclines (doxicillin).ConclusionsPsittacosis is an extremely contagious disease, caused by an intracellular germ, called “Chlamydia psittaci”, a Gram-negative bacterium, transmitted to humans in particular by infected birds, responsible for atypical pneumonia, with acute and chronic respiratory symptoms, sometimes with multi-organ failure and disseminated intravascular coagulation. Even if it is a rare respiratory disease among children, a good doctor must think about psittacosis as cause of respiratory symptoms (and not only flu or SARS-COV2), above all through a correct medical history, in order to provide a targeted antibiotic therapy. An interesting case of psittacosis in a child is being reported here, which has been treated successfully with doxycillin.

An inhaled ACE2 decoy confers protection against SARS-CoV-2 infection in preclinical models.

The Omicron variant continuously evolves under the humoral immune pressure exerted by vaccination and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and the resulting Omicron subvariants display further immune evasion and antibody escape. An engineered angiotensin-converting enzyme 2 (ACE2) decoy composed of high-affinity ACE2 and an IgG1 Fc domain could offer an alternative modality to neutralize SARS-CoV-2. We previously reported its broad spectrum and therapeutic potential in rodent models. Here, we demonstrate that the engineered ACE2 decoy retains neutralization activity against Omicron subvariants, including the currently emerging XBB and BQ.1 strains, which completely evade antibodies currently in clinical use. SARS-CoV-2, under the suboptimal concentration of neutralizing drugs, generated SARS-CoV-2 mutants escaping wild-type ACE2 decoy and monoclonal antibodies, whereas no escape mutant emerged against the engineered ACE2 decoy. Furthermore, inhalation of aerosolized decoys improved the outcomes of rodents infected with SARS-CoV-2 at a 20-fold lower dose than that of intravenous administration. Last, the engineered ACE2 decoy exhibited therapeutic efficacy for cynomolgus macaques infected with SARS-CoV-2. These results indicate that this engineered ACE2 decoy represents a promising therapeutic strategy to overcome immune-evading SARS-CoV-2 variants and that liquid aerosol inhalation could be considered as a noninvasive approach to enhance the efficacy of COVID-19 treatments.

Aerosol Inhalation of Chimpanzee Adenovirus Vectors (ChAd68) Expressing Ancestral or Omicron BA.1 Stabilized Pre-Fusion Spike Glycoproteins Protects Non-Human Primates against SARS-CoV-2 Infection.

Current COVID-19 vaccines are effective countermeasures to control the SARS-CoV-2 virus pandemic by inducing systemic immune responses through intramuscular injection. However, respiratory mucosal immunization will be needed to elicit local sterilizing immunity to prevent virus replication in the nasopharynx, shedding, and transmission. In this study, we first compared the immunoprotective ability of a chimpanzee replication-deficient adenovirus-vectored COVID-19 vaccine expressing a stabilized pre-fusion spike glycoprotein from the ancestral SARS-CoV-2 strain Wuhan-Hu-1 (BV-AdCoV-1) administered through either aerosol inhalation, intranasal spray, or intramuscular injection in cynomolgus monkeys and rhesus macaques. Compared with intranasal administration, aerosol inhalation of BV-AdCoV-1 elicited stronger humoral and mucosal immunity that conferred excellent protection against SARS-CoV-2 infection in rhesus macaques. Importantly, aerosol inhalation induced immunity comparable to that obtained by intramuscular injection, although at a significantly lower dose. Furthermore, to address the problem of immune escape variants, we evaluated the merits of heterologous boosting with an adenovirus-based Omicron BA.1 vaccine (C68-COA04). Boosting rhesus macaques vaccinated with two doses of BV-AdCoV-1 with either the homologous or the heterologous C68-COA04 vector resulted in cross-neutralizing immunity against WT, Delta, and Omicron subvariants, including BA.4/5 stronger than that obtained by administering a bivalent BV-AdCoV-1/C68-COA04 vaccine. These results demonstrate that the administration of BV-AdCoV-1 or C68-COA04 via aerosol inhalation is a promising approach to prevent SARS-CoV-2 infection and transmission and curtail the pandemic spread.

An IgM-like inhalable ACE2 fusion protein broadly neutralizes SARS-CoV-2 variants

Many of the currently available COVID-19 vaccines and therapeutics are not effective against newly emerged SARS-CoV-2 variants. Here, we developed the metallo-enzyme domain of angiotensin converting enzyme 2 (ACE2)—the cellular receptor of SARS-CoV-2—into an IgM-like inhalable molecule (HH-120). HH-120 binds to the SARS-CoV-2 Spike (S) protein with high avidity and confers potent and broad-spectrum neutralization activity against all known SARS-CoV-2 variants of concern. HH-120 was developed as an inhaled formulation that achieves appropriate aerodynamic properties for rodent and monkey respiratory system delivery, and we found that early administration of HH-120 by aerosol inhalation significantly reduced viral loads and lung pathology scores in male golden Syrian hamsters infected by the SARS-CoV-2 ancestral strain (GDPCC-nCoV27) and the Delta variant. Our study presents a meaningful advancement in the inhalation delivery of large biologics like HH-120 (molecular weight (MW) ~ 1000 kDa) and demonstrates that HH-120 can serve as an efficacious, safe, and convenient agent against SARS-CoV-2 variants. Finally, given the known role of ACE2 in viral reception, it is conceivable that HH-120 has the potential to be efficacious against additional emergent coronaviruses.

Public Health Experts Ask CDC Director to Broaden Input on Revisions to Key Infection Control Guidelines.

On July 20, 2023 a letter was sent to the Director of the Centers for Disease Control and Prevention requesting the agency's Healthcare Infection Control Practice Advisory Committee seek input from more stakeholders and the public, recognize the importance of infectious disease transmission by inhalation of human-generated aerosols, and ensure the application of interventions from all levels of the control hierarchy.

A Technical Feasibility of Aqueous Aerosol Generation Based on the Flashing Jet: Effects of Overheat Degree, Jetting Rate, Jetting Volume, and Liquid Type

AbstractA previously established flashing jet inhaler prototype (FJ prototype) can produce an aqueous aerosol but cannot steadily provide inhalable aerosol (2–5 μm). This study aims to optimize the atomization performance of the FJ prototype and generate inhalable aqueous aerosols. The effects of overheat degree, jetting rate, jetting volume, and liquid type on atomization performance were assessed by determining output aerosol's mass median aerodynamic diameter (MMAD) and aerodynamic particle size distribution. Drug distribution of active ingredients in different liquid types was also measured. A Pari nebulizer was used as a reference device. Our data suggested that MMAD is negatively correlated with the overheat degree and jetting rate, but has no significant relationship with the jetting volume. The effect of jetting rate is weaker than that of the overheat degree. When normal saline was used as the atomization liquid, output aerosol's MMAD at the FJ prototype and Pari nebulizer were 1.98 ± 0.18 and 2.50 ± 0.81 μm, respectively. The addition of a surfactant significantly decreases MMAD both in solution and in suspension, but the suspended particles had no effect on the residual level and atomization performance of the FJ prototype. When ventolin was used as the atomization liquid, the MMAD of the FJ prototype and Pari nebulizer was 2.1 ± 0.2 and 1.7 ± 0.2 μm, respectively, while the fine particle dosage (FPD) in percent of the nominal dose (%ND) was 50.4 ± 3.1 and 53.1 ± 7.2%, respectively. When pulmicort respules was used as the atomization liquid, the MMAD of the FJ prototype and Pari nebulizer was 2.5 ± 0.5 and 4.6 ± 0.2 μm respectively, while the FPD (%ND) was 30.1 ± 5.6 and 58.6 ± 5.1%, respectively. The FJ prototype not only delivers inhalable aqueous aerosol but also has a potential advantage in the atomization of suspension or poorly soluble drugs.

The air and dust invisible mycobiome of urban domestic environments

Air and dust harbor a dynamic fungal biome that interacts with residential environment inhabitants usually with negative implications for human health. Fungal air and dust synthesis were investigated in houses across the Athens Metropolitan area. Active and passive culture dependent methods were employed to sample airborne and dustborne fungi for two sampling periods, one in winter and the other in summer. A core mycobiome was revealed both in air and dust constituted of the dominant Penicillium, Cladosporium, Aspergillus, Alternaria and yeasts and accompanied by several common and rare components. Penicillium and Aspergillus diversity included 22 cosmopolitan species, except the rarely found Penicillium citreonigrum, P. corylophilum, P. pagulum and Talaromyces albobiverticillius which are reported for the first time from Greece. Fungal concentrations were significantly higher during summer for both air and dust. Excessive levels of inhalable aerosol constituted mainly by certain Penicillium species were associated with indoor emission sources as these species are household molds related to food commodities rot. The ambient air fungal profile is a determinant factor of indoor fungal aerosol which subsequently shapes dustborne mycobiota. Indoor fungi can be useful bioindicators for indoor environment quality and at the same time provide insight to indoor fungal ecology.

Beyond the label: current evidence and future directions for the interrelationship between electronic cigarettes and mental health.

Electronic cigarette use has dramatically increased over the last decade. With this recent technological development and wide range of constituents in various products, putative adverse effects on the brain and body have been largely unexplored. Here, we review current evidence linking electronic nicotine cigarette use with potential health consequences and provide evidence supporting an association between drug use and depression in humans. We also examine the biological effects of individual constituents in electronic cigarette aerosols, which include labeled ingredients, such as propylene glycol, vegetable glycerin, nicotine, and flavorants, as well as unlabeled ingredients found in the aerosols, such as carbonyls and heavy metals. Lastly, we examine the effects of electronic cigarette use on endogenous metabolism via changes in cytochrome P450 enzymes, which can thereby impact therapeutic outcomes. While the current evidence offers insight into the potential effects of electronic cigarette use on biological processes, further studies are necessary to determine the long-term clinical relevance of aerosol inhalation.

Measuring Anatomical Distributions of Ventilation and Aerosol Deposition with PET-CT.

In disease, lung function and structure are heterogeneous, and aerosol transport and local deposition vary significantly among parts of the lung. Understanding such heterogeneity is relevant to aerosol medicine and for quantifying mucociliary clearance from different parts of the lung. In this chapter, we describe positron emission tomography (PET) imaging methods to quantitatively assess the deposition of aerosol and ventilation distribution within the lung. The anatomical information from computed tomography (CT) combined with the PET-deposition data allows estimates of airway surface concentration and peripheral tissue dosing in bronchoconstricted asthmatic subjects. A theoretical framework is formulated to quantify the effects of heterogeneous ventilation, uneven aerosol ventilation distribution in bifurcations, and varying escape from individual airways along a path of the airway tree. The framework is applied to imaging data from bronchoconstricted asthmatics to assess the contributions of these factors to the unevenness in lobar deposition. Results from this analysis show that the heterogeneity of ventilation contributes on average to more than one-third of the variability in interlobar deposition. Actual contribution of ventilation in individual lungs was variable and dependent on the breathing rate used by the subject during aerosol inhalation; the highest contribution was in patients breathing slowly. In subjects breathing faster, contribution of ventilation was reduced, with more expanded lobes showing lower deposition per unit ventilation than less expanded ones in these subjects. The lobar change in expansion measured from two static CT scans, which is commonly used as a surrogate for ventilation, did not correlate with aerosol deposition or with PET-measured ventilation. This suggests that dynamic information is needed to provide proper estimates of ventilation for asthmatic subjects. We hope that the enhanced understanding of the causes of heterogeneity in airway and tissue dosing using the tools presented here will help to optimize therapeutic effectiveness of inhalation therapy while minimizing toxicity.

Chronic Inhalation of Pod-based e-cigarette Aerosols on Inflammatory Biomarkers in the Central Nervous and Peripheral Systems

Electronic cigarettes (e-cigs) use has been dramatically increased recently, especially among youths. In this study, we evaluated the effect of one- and three-months continuous exposure to e-cig vapor (JUUL pods), containing high nicotine concentration, on the expression of glutamate receptors and transporters and mainly the associated neuroinflammatory markers in drug reward brain regions such as nucleus accumbens (NAc) core (NAc-core), NAc shell (NAc-shell) and hippocampus (HIP) in female C57BL/6 mice. We revealed that three months’ exposure to mint or mango flavored-JUUL (containing 5% nicotine, 59 mg/ml) induced upregulation in metabotropic glutamate receptor 1 (mGluR1) and postsynaptic density protein 95 (phosphorylated and total PSD95) expression, and downregulation of mGluR5 and glutamate transporter 1 (GLT-1) in the NAc-shell. Three months’ exposure to JUUL induced upregulation of mGluR5 and GLT-1 expression in the HIPP. We further revealed that mice exposed to JUUL Mango and JUUL Mint for one month had significantly increased TNF-α expression in the NAc-core and NAc-shell, with elevation in IL-1β as well. NAc-shell also showed significantly increased levels of IL-6 and HMGB-1 for both flavors. There were significantly increased levels of TNF-α in the NAc-core and NAc-shell for both Mint- and Mango-exposed JUUL mice for three months. NAc-shell also showed significantly increased levels of IL-1β, IL-6, HMGB-1, and RAGE after three months of JULL exposure, while the hippocampus showed significantly decreased levels of HMGB-1 for both flavors. These findings demonstrated that exposure to e-cig vapor containing high nicotine concentrations induced differential effects on glutamatergic system as well as induction of proinflammatory markers in the brain.

Retracted: Influenza A Virus Production in Mouse Lung Is Inhibited by Inhalation of Aerosol Polyethylenimine/Short Hairpin RNA Plasmid Complexes.

[This retracts the article DOI: 10.1155/2022/7404813.].

Covid 19 and beyond: a procedure for HVAC systems to address infectious aerosol illness transmission

From pandemic to seasonal, the COVID-19 pandemic experience suggests many common respiratory infections rather than likely having a fomite etiology as previously thought, are primarily caused by the inhalation of infectious aerosols shed by ill persons during coughing and normal breathing and talking. Given this new understanding, the good news is that, unlike indoor-sourced noxious and irritating gases that can only be mitigated practically by diluting them with outdoor air ventilation, the indoor infectious aerosol illness transmission route can be addressed by circulating already conditioned air through commonplace commercial filters. Given that infectious aerosols released from the breath of occupants were practically an unknown vector of respiratory disease in the healthcare community for many decades, understandably HVAC regulations have not addressed this issue yet. However, this is about to change. To further this new end, this paper develops the formulae needed to set conditioned air recirculation rates through such filters for design infectious aerosol emission and inhalation rates, HID values, exposure times and occupancies, and target significantly lower than currently normal airborne infection reproduction rates. The analysis extends the equations previously developed for group inhalation of infectious aerosols to develop equations predicting the number of infections likely to occur from this inhalation and the rate of disease spread (reproduction). The governing equations provided and exemplified use group exposures since the number of infections (reproduction number) is group based. Examples using the equations provided are given for many different settings and two case study findings are compared with their predictions. Some settings such as the typical office are shown to already have a relatively low infection reproduction rate. Alternatively, others such as a typical school classroom or a longer commercial air flight require increased filtered ventilation air flows to yield a similarly low reproduction rate. The formulae and their application will be of interest to government and industry health and HVAC standard setting bodies.

Study on the mechanism of PM2.5 affecting Th1/Th2 immune imbalance through the notch signaling pathway in asthmatic mice.

Some research has shown that PM2.5 causes Th1/Th2 immune imbalance and aggravates asthma. However, the exact mechanism of PM2.5 causing aggravation of asthma remains unclear. The purpose of this study was to investigate whether exposure to PM2.5 exacerbates Th1/Th2 immune imbalance through the Notch signaling pathway. Eight-week-old SPF female BALF/c mice were sensitized by ovalbumin to establish an asthma mouse model. PM2.5 exposure was carried out by aerosol inhalation of PM2.5 (510μg/m3) after each provocation. The lung function of mice was measured and Splenic T lymphocyte subsets were detected. Notch signaling pathway was tested. The levels of interferon (IFN)-γ and interleukin (IL)-4 in serum and bronchoalveolar lavage fluid were determined. The results showed that the expression of the mRNA and protein of Notch1 and Hes1 in the asthma group were significantly higher than those in healthy controls. The levels of IL-4 were also remarkably high; while the levels of IFN-γ were remarkably low in serum and BALF, the Th1% and Th1/Th2 ratios were significantly lower, and Th2% was significantly higher in the asthma group than in the healthy controls. PM2.5 promoted further activation of the Notch signaling pathway and aggravated Th1/Th2 immune imbalance in asthmatic mice. γ-secretase inhibitor can partially inhibit the activation of the Notch signaling pathway and alleviate aggravation of immune imbalance. In conclusion, the asthmatic mice had a Th1/Th2 immune imbalance and an overactivated Notch signaling pathway. PM2.5 further aggravated Th1/Th2 immune imbalance by activating the Notch signaling pathway.

Resuspension of Seeded Particles Containing Live Influenza A Virus in a Full-Scale Laboratory

Many respiratory viruses, including influenza and SARS-CoV-2, are transmitted via the emission and inhalation of infectious respiratory aerosols in indoor environments. Resuspended particles from indoor surfaces and clothing can be a major source of airborne microbiological contaminants in indoor environments; however, it is unknown whether resuspended viruses contribute substantially to disease transmission. In this study, we investigated the resuspension via human walking activity of influenza A virus H3N2 laboratory strain, which was generated through a nebulizer into a sealed, unventilated biosafety level 2 (BSL-2) laboratory. The mean airborne viral concentrations following the resuspension events (3.7×103 viral RNA copies m−3) were two orders of magnitude lower than those following direct emission via the nebulizer (1.1×105 viral RNA copies m−3). The calculated resuspension emission factor (normalized ratio of the airborne mass to mass available for resuspension on the surface) of 10−3 was similar to reported values for 1–2 μm particles. Thus, depending on the infectious dose and viability of the virus, resuspension of settled respiratory viruses could lead to transmission, but the risk appears to be much lower than for direct respiratory emissions. To our knowledge, this is the first full-scale experimental study designed to quantify virus resuspension.

A Quick Method for the Determination of the Fraction of Freebase Nicotine in Electronic Cigarettes.

Recently, many electronic cigarettes (ECIGs) manufacturers have begun offering e-liquids, known as "nicotine salts". These salts that have started gaining big popularity among users can be formed by adding weak acid to e-liquid mixtures consisting of propylene glycol (PG), vegetable glycerin (VG), flavors, and nicotine. The latter can exist in two forms: monoprotonated (mp) and freebase (fb) based on the pH of the matrix. Over the years, the determination of the fraction of fb was found important to policymakers as the prevalence of this form in ECIGs has been associated with the harshness sensory of inhalable aerosols. Liquid-liquid extraction (LLE), 1H NMR, and Henderson-Hasselback have been developed to deduce the fraction of fb; however, these methods were found to be time-consuming and have shown some challenges mainly due to the presence of a non-aqueous matrix consisting of PG and VG. This paper presents a quick non-aqueous pH measurement-based method that allows a quick determination of the fraction fb by just measuring the pH and the dielectric constant of the e-liquid. Then, by inputting these values into an established mathematical relationship, the fraction fb can be deduced. The relationship between pH, dielectric constant, and fb relies on knowing the values of the acidity dissociation constants of nicotine, which were determined for the first time in various PG/VG mixtures using a non-aqueous potentiometric titration. To validate the proposed method, the fraction fb was determined for commercials and lab-made nicotine salts utilizing the pH and LLE methods. The variation between the two methods was (<8.0%) for commercial e-liquids and lab-made nicotine salts containing lactic acid and salicylic acid. A larger discrepancy of up to 22% was observed for lab-made nicotine salts containing benzoic acid, which can be attributed to the stronger affinity of benzoic acid to toluene in the LLE method.

Size-dependent aerosol penetration through facemasks and respirators (FMRs) during simulated exhalation and cough

Despite a good understanding of the filtration properties of various face and nose coverings during aerosol inhalation, their effectiveness in reducing aerosol emitted by infected individuals during exhalation or coughing is not fully characterized. This paper presents experiments conducted using a silicone model of a standardized face for controlled flow patterns (steady flow, typical exhalation or flow pulses associated with coughing/sneezing) used to push test aerosols (0.5–20 μm) through valved or non-valved respirators, surgical masks and cloth masks. The aerosol characteristics determined during experiments allowed quantitative comparison of size-dependent aerosol penetration for different flow conditions. The results showed that only aerosols smaller than 8.5–10 μm more easily penetrated beyond the face coverings tested but their concentrations outside were significantly reduced. Calculations based on experimental data showed that the amount of emitted airborne particles that can be inhaled into the lower respiratory tract of bystanders was reduced 1.3–5.7 times compared to the case when the spreader does not use a mask. These results bring additional quantitative information on the role of selected masks and respirators in reducing aerosol emission that potentially contribute to the transmission of viral diseases, including COVID.