Respiratory Fluid Research Articles

Anthropogenic activities and COVID-19 effects on natural water bodies: Arroyo Seco’s case

Concerns about pollution in Arroyo Seco, an important natural water body in the Monterrey Metropolitan Area, have been reported due to possible wastewater discharges and solid waste mismanagement, turning the river into a potential public health hazard in the context of the COVID-19 pandemic. As a result, a volunteer clean-up campaign denominated “Arroyo Vivo” has been promoted by Distrito Tec and the Campana-Altamira initiative. To aid in the efforts, ammonium, nitrates, nitrites, and sulfate concentrations, total solids, and total organic matter were measured in parallel with SARS-CoV-2 detection and quantification in river water samples. Compared with applicable regulations (NOM-001-SEMARNAT-2021, NOM-127-SSA1-2021), total suspended solid levels (55-365 mg/L) were found above the maximum limit (84 mg/L), while ammonium (0.0175-0.198 mg/L), nitrite (0.0585-0.169 mg/L), nitrate (1.065-3.285 mg/L), sulfate (91.2-111 mg/L), and chemical oxygen demand (16.95-43.1 mg/L) were consistently below the maximum limits (0.50, 0.90, 11.00, 84.00, 400.00, and 100.00 mg/L, respectively), showing that no large-scale wastewater discharges had taken place in Arroyo Seco. However, SARS-CoV-2 genetic material was detected at three sampling sites, indicating some degree of sewage leakage and inadequate management of solid waste containing respiratory fluids of infected patients. While reports indicate that water bodies are not sources of SARS-CoV-2 infection in surrounding populations, it proves that waste disposal policies must be enforced more strictly to ensure water quality and environmental protection towards sustainable development. Nonetheless, continued efforts to screen concerning contaminants are still needed to fully assess the environmental status of the stream and propose relevant public policy.

Toward microfluidic integration of respiratory and renal organ support in a single cartridge.

Extracorporeal organ assist devices provide lifesaving functions for acutely and chronically ill patients suffering from respiratory and renal failure, but their availability and use is severely limited by an extremely high level of operational complexity. While current hollow fiber-based devices provide high-efficiency blood gas transfer and waste removal in extracorporeal membrane oxygenation (ECMO) and hemodialysis, respectively, their impact on blood health is often highly deleterious and difficult to control. Further challenges are encountered when integrating multiple organ support functions, as is often required when ECMO and ultrafiltration (UF) are combined to deal with fluid overload in critically ill patients, necessitating an unwieldy circuit containing two separate cartridges. We report the first laboratory demonstration of simultaneous blood gas oxygenation and fluid removal in single microfluidic circuit, an achievement enabled by the microchannel-based blood flow configuration of the device. Porcine blood is flowed through a stack of two microfluidic layers, one with a non-porous, gas-permeable silicone membrane separating blood and oxygen chambers, and the other containing a porous dialysis membrane separating blood and filtrate compartments. High levels of oxygen transfer are measured across the oxygenator, while tunable rates of fluid removal, governed by the transmembrane pressure (TMP), are achieved across the UF layer. Key parameters including the blood flow rate, TMP and hematocrit are monitored and compared with computationally predicted performance metrics. These results represent a model demonstration of a potential future clinical therapy where respiratory support and fluid removal are both realized through a single monolithic cartridge.

Respiratory Fluid Mechanics of the Effect of Mouth Breathing on High-Arched Palate: Computational Fluid Dynamics Analyses.

Computational fluid dynamics (CFD) was introduced into the study of palate growth and development to explain the mechanisms by which mouth breathing affects palate descent from an aerodynamic perspective. Cone beam computed tomography (CBCT) data were used to reconstruct a 3-dimensional model during natural mouth breathing of a volunteer. The model was imported into CFX 19.0 for numerical simulation of nasal breathing, mouth-nasal breathing, and mouth breathing. The pressure in the oronasal cavity was analyzed, and the pressure difference between the oral and nasal surfaces of hard palate under different breathing patterns was calculated. CFD can be used to simulate the stress on the oral and nasal surfaces of the palate under different breathing patterns. The pressure differences and resultant force between the oral and nasal surfaces of the hard palate during nasal inspiration, nasal expiration, mouth-nasal inspiration, mouth-nasal expiration, mouth inspiration, and mouth expiration were 0Pa, 4Pa (upward), 9Pa (upward), 3Pa (downward), 474Pa (upward), 263Pa (downward), respectively, and 87.99N (upward), 88.03N (upward), 88.01N (upward), 88.01N (upward), 88.05N (upward), 87.94N (upward), respectively. Therefore, CFD can be used to investigate the growth and development of the palate. When the volunteer opened his mouth, the pressure difference between the oral and nasal surfaces of the hard palate was about 88N upward regardless of whether there was airflow in the mouth. The reversal of the direction of the force on the hard palate may be one of the factors affecting its descent of it.

Bactericidal Activity of Superabsorbent Polymer Granules for Their Applications in Respiratory Fluid Solidification Systems.

Disposal of respiratory secretions from patients having contagious diseases (e.g., COVID-19 and tuberculosis) poses a high risk of infection for healthcare workers. AcryloSorb canister liner bags are highly efficient for the safe handling of contagious respiratory secretions via solidification and disinfection processes. The canister liner bags are lined with disinfectant-impregnated superabsorbent polymer (DSAP) granules. The liner structure in the bag has a patented design that has upward progressive absorbent availability (Indian Patent application # 202041019872). AcryloSorb canister liner bags can decontaminate the fluid secretions absorbed in the bag and solidify within 10 min. The present study focused on the bactericidal effect of DSAP using Gram-negative bacteria, Klebsiella pneumoniae, and Gram-positive bacteria, methicillin-resistantStaphylococcus aureus (MRSA). Disinfectants such as peracetic acid (ethaneperoxic acid), sodium dichloroisocyanurate (sodium 3,5-dichloro-2,4,6-trioxo-1,3,5-triazinan-1-ide), rose bengal (disodium; 2,3,4,5-tetrachloro-6-(2,4,5,7-tetraiodo-3-oxido-6-oxoxanthen-9-yl) benzoate), and N,N-dimethyl-N-[3-(triethoxysilyl)propyl]octadecan-1-aminium chloride at different weight ratios were impregnated in superabsorbent polymer (SAP) granules. The bactericidal activities of DSAP were studied along with its solidification capacity. Disinfectants showed different bactericidal activities when impregnated with SAP granules. For example, peracetic acid-impregnated SAP granules (DSAP-P) showed 100% bactericidal activity for both Klebsiella pneumoniae and MRSA at 0.5 wt % peracetic acid. Sodium dichloroisocyanurate-impregnated SAP granules showed 100% bactericidal activity only at 5 wt % sodium dichloroisocyanurate (DSAP-S5). Even though peracetic acid was highly effective, SAP granules collapsed when impregnated with peracetic acid. The ease of handling, disinfection efficacy, and preserving the morphology of SAP granules make DSAP-S5, a suitable candidate for AcryloSorb canister liner bags.

Variability in Donor Lung Culture and Relative Humidity Impact the Stability of 2009 Pandemic H1N1 Influenza Virus on Nonporous Surfaces.

Respiratory viruses can be transmitted by multiple modes, including contaminated surfaces, commonly referred to as fomites. Efficient fomite transmission requires that a virus remain infectious on a given surface material over a wide range of environmental conditions, including different relative humidities. Prior work examining the stability of influenza viruses on surfaces has relied upon virus grown in media or eggs, which does not mimic the composition of virus-containing droplets expelled from the human respiratory tract. In this study, we examined the stability of the 2009 pandemic H1N1 (H1N1pdm09) virus on a variety of nonporous surface materials at four different humidities. Importantly, we used virus grown in primary human bronchial epithelial cell (HBE) cultures from different donors to recapitulate the physiological microenvironment of expelled viruses. We observed rapid inactivation of H1N1pdm09 on copper under all experimental conditions. In contrast to copper, viruses were stable on polystyrene plastic, stainless steel, aluminum, and glass, at multiple relative humidities, but greater decay on acrylonitrile butadiene styrene (ABS) plastic was observed at short time points. However, the half-lives of viruses at 23% relative humidity were similar among noncopper surfaces and ranged from 4.5 to 5.9 h. Assessment of H1N1pdm09 longevity on nonporous surfaces revealed that virus persistence was governed more by differences among HBE culture donors than by surface material. Our findings highlight the potential role of an individual's respiratory fluid on viral persistence and could help explain heterogeneity in transmission dynamics. IMPORTANCE Seasonal epidemics and sporadic pandemics of influenza cause a large public health burden. Although influenza viruses disseminate through the environment in respiratory secretions expelled from infected individuals, they can also be transmitted by contaminated surfaces where virus-laden expulsions can be deposited. Understanding virus stability on surfaces within the indoor environment is critical to assessing influenza transmission risk. We found that influenza virus stability is affected by the host respiratory secretion in which the virus is expelled, the surface material on which the droplet lands, and the ambient relative humidity of the environment. Influenza viruses can remain infectious on many common surfaces for prolonged periods, with half-lives of 4.5 to 5.9 h. These data imply that influenza viruses are persistent in indoor environments in biologically relevant matrices. Decontamination and engineering controls should be used to mitigate influenza virus transmission.

Effect of cartilaginous rings in tracheal flow with stenosis

BackgroundIn respiratory fluid dynamics research, it is typically assumed that the wall of the trachea is smooth. However, the trachea is structurally supported by a series of cartilaginous rings that create undulations on the wall surface, which introduce perturbations into the flow. Even though many studies use realistic Computer Tomography (CT) scan data to capture the complex geometry of the respiratory system, its limited spatial resolution does not resolve small features, including those introduced by the cartilaginous rings.ResultsHere we present an experimental comparison of two simplified trachea models with Grade II stenosis (70% blockage), one with smooth walls and second with cartilaginous rings. The use a unique refractive index-matching method provides unprecedented optical access and allowed us to perform non-intrusive velocity field measurements close to the wall (e.g., Particle Image Velocimetry (PIV)). Measurements were performed in a flow regime comparable to a resting breathing state (Reynolds number ReD = 3350). The cartilaginous rings induce velocity fluctuations in the downstream flow, enhancing the near-wall transport of momentum flux and thus reducing flow separation in the downstream flow. The maximum upstream velocity in the recirculation region is reduced by 38%, resulting in a much weaker recirculation zone— a direct consequence of the cartilaginous rings.ConclusionsThese results highlight the importance of the cartilaginous rings in respiratory flow studies and the mechanism to reduce flow separation in trachea stenosis.

Computer-assisted drug repurposing for thymidylate kinase drug target in monkeypox virus.

Monkeypox is a zoonotic disease caused by brick-shaped enveloped monkeypox (Mpox) virus that belongs to the family of ancient viruses known as Poxviridae. Subsequently, the viruses have been reported in various countries. The virus is transmitted by respiratory droplets, skin lesions, and infected body fluids. The infected patients experience fluid-filled blisters, maculopapular rash, myalgia, and fever. Due to the lack of effective drugs or vaccines, there is a need to identify the most potent and effective drugs to reduce the spread of monkeypox. The current study aimed to use computational methods to quickly identify potentially effective drugs against the Mpox virus. In our study, the Mpox protein thymidylate kinase (A48R) was targeted because it is a unique drug target. We screened a library of 9000 FDA-approved compounds of the DrugBank database by using various in silico approaches, such as molecular docking and molecular dynamic (MD) simulation. Based on docking score and interaction analysis, compounds DB12380, DB13276, DB13276, DB11740, DB14675, DB11978, DB08526, DB06573, DB15796, DB08223, DB11736, DB16250, and DB16335 were predicted as the most potent. To examine the dynamic behavior and stability of the docked complexes, three compounds-DB16335, DB15796, and DB16250 -along with the Apo state were simulated for 300ns. The results revealed that compound DB16335 revealed the best docking score (-9.57 kcal/mol) against the Mpox protein thymidylate kinase. Additionally, during the 300 ns MD simulation period, thymidylate kinase DB16335 showed great stability. Further, in vitro and in vivo study is recommended for the final predicted compounds.

P217 SHORT–TERM EFFECTS OF DAPAGLIFLOZIN ON CARDIAC BIOMARKERS, FLUID RETENTION, RENAL AND PULMONARY FUNCTION IN HFREF PATIENTS: NOT AS GOOD AS EXPECTED

Abstract Background Sodium–glucose co–transporter–2 inhibitors (SGLT2–i) are currently a standard therapy for patients with heart failure with reduced ejection fraction (HFrEF). Still, their potential benefits on biomarkers, respiratory function parameters and fluid retention have not been extensively studied. Bioimpedance vector analysis (BIVA) has emerged as a new tool capable of assessing congestion, providing an estimate of the total body water and hydration index (HI). BIVA is more accurate than NT–proBNP in detecting peripheral congestion in chronic heart failure and can be used to evaluate the effects of the treatment. This study aims to assess the short–term effects of Dapagliflozin on spirometry, diffusing capacity of the lungs for carbon monoxide (DLCO), cardiac biomarkers, and BIVA. Methods Stable HF patients (EF <40%, NYHA class II or III) eligible for SGLT2–I therapy according to guidelines underwent standard spirometry, DLCO, BIVA and venous blood sampling at baseline (V0) and after 2–4 weeks of therapy (V1). Results Patients characteristics (N=32) at baseline are shown in Table 1. None of the patients interrupted the treatment and/or experienced adverse events. After 26±6 days, we observed worsening of renal function (eGFR from 73.1±28.5 mL/min/1.73m2 to 67.4±27.0 mL/min/1.73m2, p<0.001) and potassium levels (4.36±0.36 mEq/l vs 4.58±0.57 mEq/l, p= 0.017). There were no significant changes in NT–proBNP levels (1378 [615–2542] ng/l vs 1034 [554–2552] ng/l, p= 0.538). HI, total body water, DLCO and spirometry values did not change. On the contrary, a mild reduction in hsTnI was observed (13.88 [9.24–26.8] ng/l vs 11.58 [7.7–24.2] ng/l). Conclusions Our study did not detect short–term effects of Dapagliflozin on spirometry values, DLCO, fluid retention and NT–proBNP. As revealed in DAPA–HF trial, a mild worsening of potassium and serum creatinine levels was observed. Taken together, these results suggest that the favourable effects of Dapagliflozin could unfold over a longer period of time. A more extended follow–up and a larger population are needed to confirm these preliminary data.

Wearable Graphene-based smart face mask for Real-Time human respiration monitoring

After the pandemic of SARS-CoV-2, the use of face-masks is considered the most effective way to prevent the spread of virus-containing respiratory fluid. As the virus targets the lungs directly, causing shortness of breath, continuous respiratory monitoring is crucial for evaluating health status. Therefore, the need for a smart face mask (SFM) capable of wirelessly monitoring human respiration in real-time has gained enormous attention. However, some challenges in developing these devices should be solved to make practical use of them possible. One key issue is to design a wearable SFM that is biocompatible and has fast responsivity for non-invasive and real-time tracking of respiration signals. Herein, we present a cost-effective and straightforward solution to produce innovative SFMs by depositing graphene-based coatings over commercial surgical masks. In particular, graphene nanoplatelets (GNPs) are integrated into a polycaprolactone (PCL) polymeric matrix. The resulting SFMs are characterized morphologically, and their electrical, electromechanical, and sensing properties are fully assessed. The proposed SFM exhibits remarkable durability (greater than1000 cycles) and excellent fast response time (∼42 ms), providing simultaneously normal and abnormal breath signals with clear differentiation. Finally, a developed mobile application monitors the mask wearer's breathing pattern wirelessly and provides alerts without compromising user-friendliness and comfort.

Application of Nanotechnology in a Novel Air Purifier for Remediation of Airborne Pathogen and to Prevent the Spread of COVID-19

The spread of COVID-19 occurs via airborne transmission. With a constant and variable spread of COVID-19, indoor air-quality has become a major concern all over the world. People who are infected with COVID can release particles and droplets of respiratory fluids that contain the SARS CoV-2 virus into the air when they exhale (e.g., quiet breathing, speaking, singing, exercise, coughing, sneezing). Once infectious droplets are exhaled, they move outward from the person (the source) into the surrounding environment; these droplets carry the virus and transmit infection. Indoors, the very fine droplets and particles will continue to spread through the air in the room or space and can accumulate. Harmful pathogenic organisms like fungi, bacteria and viruses, as the one responsible for causing contagious diseases like the ongoing pandemic of COVID-19 can also be successfully destroyed and neutralized. We have developed and studied the efficiency of the AFL Mini Sanifier II® in a simulated environment of a fiberglass chamber using various types of meters to assess the suspended particulate matter (PM) in the ambient air. We also report the development of a novel face mask that was assessed for safety measures and further improvement by the researchers in the West Texas A&M University. The mask is user friendly and portable, equipped with a small internal fan that supplies a continuous air to the user preventing the suffocating effect caused by the other masks. The novel mini air purifier is equipped with the advanced nanotechnology that cleans and sanitizes both the air and surfaces and subsequently has been shown to reduce common allergy, asthma and hay fever related symptoms. This mask and the mini air purifier function in an advanced way to combat all forms of airborne pathogens including the bacteria, viruses, mold spores and harmful Volatile Organic Compounds (VOC) present in the air.

Proteomic characteristics and diagnostic potential of exhaled breath particles in patients with COVID-19

BackgroundSARS-CoV-2 has been shown to predominantly infect the airways and the respiratory tract and too often have an unpredictable and different pathologic pattern compared to other respiratory diseases. Current clinical diagnostical tools in pulmonary medicine expose patients to harmful radiation, are too unspecific or even invasive. Proteomic analysis of exhaled breath particles (EBPs) in contrast, are non-invasive, sample directly from the pathological source and presents as a novel explorative and diagnostical tool.MethodsPatients with PCR-verified COVID-19 infection (COV-POS, n = 20), and patients with respiratory symptoms but with > 2 negative polymerase chain reaction (PCR) tests (COV-NEG, n = 16) and healthy controls (HCO, n = 12) were prospectively recruited. EBPs were collected using a “particles in exhaled air” (PExA 2.0) device. Particle per exhaled volume (PEV) and size distribution profiles were compared. Proteins were analyzed using liquid chromatography-mass spectrometry. A random forest machine learning classification model was then trained and validated on EBP data achieving an accuracy of 0.92.ResultsSignificant increases in PEV and changes in size distribution profiles of EBPs was seen in COV-POS and COV-NEG compared to healthy controls. We achieved a deep proteome profiling of EBP across the three groups with proteins involved in immune activation, acute phase response, cell adhesion, blood coagulation, and known components of the respiratory tract lining fluid, among others. We demonstrated promising results for the use of an integrated EBP biomarker panel together with particle concentration for diagnosis of COVID-19 as well as a robust method for protein identification in EBPs.ConclusionOur results demonstrate the promising potential for the use of EBP fingerprints in biomarker discovery and for diagnosing pulmonary diseases, rapidly and non-invasively with minimal patient discomfort.

UVC-Based Air Disinfection Systems for Rapid Inactivation of SARS-CoV-2 Present in the Air

The World Health Organization (WHO) declared in May 2021 that SARS-CoV-2 is transmitted not only by close contact with infectious respiratory fluids from infected people or contaminated materials but also indirectly through air. Airborne transmission has serious implications for the control measures we can deploy, given the emergence of more transmissible variants. This emphasizes the need to deploy a mechanism to reduce the viral load in the air, especially in closed and crowded places such as hospitals, public transport buses, etc. In this study, we explored ultraviolet C (UVC) radiation for its ability to inactivate the SARS-CoV-2 particles present in aerosols and designed an air disinfection system to eliminate infectious viruses. We studied the virus inactivation kinetics to identify the UVC dosage required to achieve maximum virus inactivation. Based on the experimental data, UVC-based devices were designed for the sanitization of air through HVAC systems in closed spaces. Further, a risk assessment model to estimate the risk reduction was applied which showed that the use of UVC radiation could result in the reduction of the risk of infection in occupied spaces by up to 90%.

Physicochemical characterization of porcine respiratory aerosol and considerations for future aerovirology.

Understanding the mechanisms which inactivate airborne viruses is a current challenge. The composition of human respiratory aerosol is poorly understood and needs to be adequately investigated for use in aerovirology studies. Here, the physicochemical properties of porcine respiratory fluid (PRF) from the trachea and lungs were investigated both in bulk solutions and in aerosols. The mass ratio of Na:K in PRF compared with cell culture media (Dulbecco's Modified Eagle Medium, DMEM), which is frequently used in aerovirology studies, was significantly lower (∼2:1 vs ∼16:1). PRF contained significantly more potassium and protein than DMEM. PRF aerosols of all samples were similarly hygroscopic to human respiratory aerosol. PRF particles could nucleate with spatially separated crystals, indicating that the protein matrix was sufficiently viscous to prevent the complete coalescence of aqueous salts prior to efflorescence. The effects of these differences in compositions on the viability of viruses are currently not well understood. The virus suspensions in aerovirology studies need to be reconsidered to adequately reflect a real-world expiration scenario.

Mpox (Monkeypox) Proctitis

HomeRadioGraphicsVol. 43, No. 3 PreviousNext Cases from the Cooky JarFree AccessMpox (Monkeypox) ProctitisCiléin Kearns , Michael Orsi, Carlos J. Sanchez, Francisco CalleCiléin Kearns , Michael Orsi, Carlos J. Sanchez, Francisco CalleAuthor AffiliationsFrom the Department of Radiology, Wellington Regional Hospital, Te Whatu Ora (Health New Zealand), Riddiford St, Wellington 6021, New Zealand, and Artibiotics, Wellington, New Zealand (C.K.); South Texas Radiology Group, San Antonio, Tex (M.O.); Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Ga (C.J.S.); and Department of Radiology, Hospital Militar Central, Universidad Militar Nueva Granada, Bogotá, Colombia (F.C.).Address correspondence to C.K. (email: [email protected]).Ciléin Kearns Michael OrsiCarlos J. SanchezFrancisco CallePublished Online:Feb 16 2023https://doi.org/10.1148/rg.220198MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Monkeypox virus is an Orthopoxvirus first identified in primates (1), although the natural reservoir is likely rodents (2). Mpox disease (formerly monkeypox disease [3]) is less contagious and milder than smallpox, with a 3%–6% mortality rate (2). The May 2022 mpox outbreak has been driven by sexual transmission in most cases, but infection may also occur by contact with lesions, respiratory fluids, contaminated fabric, and infected meat (4,5).The disease lasts 2–3 weeks and manifests with characteristic mucosal lesions (Fig 1) that may be preceded by systemic symptoms such as fever (5,6). The lesions primarily affect the anogenital area, trunk, limbs or face, and 14%–36% of patients present with proctitis (5,7). Imaging can show proctitis (Fig 2), and complications include perianal abscess or rectal perforation (7). Rare severe complications include myocarditis, epiglottitis, pneumonia, sepsis, encephalitis, and vision loss (4–6).Figure 1. Mpox characteristic rash or lesion progression, symptoms, and complications. In the current outbreak, the majority of patients have had lesions in the anogenital region, and over half have lesions on the trunk or limbs, although lesions may also be concentrated on the palms, soles, and face (5). Other symptoms may include fever, lymphadenopathy, pharyngitis, headache, lethargy, myalgia, proctitis or anorectal pain, and low mood (5). The rash or lesions last 2–3 weeks, beginning as macules that progress to papules, vesicles, and then pustules that crust, fall off, and can leave scars. (Reprinted, with permission, from Ciléin Kearns, Artibiotics, Copyright © 2023.)Figure 1.Download as PowerPointOpen in Image Viewer Figure 2. Mpox proctitis in a 61-year-old man who underwent a kidney transplant and presented with rectal bleeding and pain. A nearly circumferential ulcerated mass was found in the lower rectum on clinical examination. Biopsy results were negative for malignancy but showed inflammation. Axial (A, B) and coronal (C, D) portal venous phase CT images show circumferential thickening of the low to mid rectum with mesorectal fat stranding and lymphadenopathy (arrow in A and C), findings very similar in appearance to those of rectal cancer with metastatic adenopathy. A repeat biopsy with larger samples and fulguration was performed, and the results also were negative for malignancy, showing only inflammation, ulceration, and abscess formation. Skin lesions developed 2–3 days after the second rectal biopsy. Monkeypox Orthopoxvirus DNA was detected by real-time polymerase chain reaction on lesion swab.Figure 2.Download as PowerPointOpen in Image Viewer Viral polymerase chain reaction results from lesions are diagnostic (5,6). Treatment is supportive, but the antiviral tecovirimat (TPOXX) and vaccinia immune globulin are used in those at risk for severe disease (1,4). The JYNNEOS mpox vaccination is approved by the U.S. Food and Drug Administration, and smallpox vaccination also provides protection (1,2).Disclosures of conflicts of interest.—C.K. Editorial board member of RadioGraphics.C.K. has provided disclosures (see end of article); all other authors have disclosed no relevant relationships.

Pathogen spreading during the COVID‐19 pandemic: Understanding a global phenomenon

AbstractThis study examined news media reports published during the early months of the COVID‐19 pandemic that described people spitting, coughing, and otherwise spreading respiratory fluids to other people and objects. A search of a news archive yielded more than 800 news articles published during March, April, and May, 2020, from which N = 325 cases of intentional pathogen spreading were identified. This was during the early part of the pandemic when the world was still trying to reach an understanding of how to deal with the pandemic. Collected news articles showed that cases of intentional pathogen spreading were reported to have occurred in 14 countries on 5 continents on most days (78.3%) of the 3‐month period considered. In 43% of cases, perpetrators claimed to be infected with the SARS‐CoV‐2 virus. Frontline key workers, passersby, and retail workers were the most frequent targets. The findings suggest that more needs to be learned about intentional pathogen spreading behavior, with the goals of reducing its occurrence in future pandemics and protecting vulnerable targets.

Effectiveness of N95 Mask in Preventing COVID-19 Transmission.

N95 mask has emerged as a potential measure to mitigate the airborne transmission of respiratory disease such as COVID-19. Herein, we experimentally investigated the impact and interaction of pure water droplets as surrogate to respiratory droplets with the different layers of a commercially available N95 mask to demonstrate the penetration and passage-capability of respiratory fluids through the different layers. The penetration of an impacting droplet through the mask layers was characterized by elucidating the ejection of secondary droplets from the rear-side surface of the target mask material. In addition, the passage of respiratory fluids through the mask layers was characterized by capillary imbibition of the droplet liquid through the pores, as a function of wettability of the mask material. Droplet impact at Weber numbers We = 208 and 416 has been considered in the present study; the chosen We range corresponds to that of cough droplets realized in real respiratory events. Each layer of the N95 mask is hydrophobic that prevents capillary imbibition through the pores: a sessile droplet placed over the surface exhibits classical diffusion-limited evaporation. Droplet impact experiments on N95 mask layer surfaces reveal that a single layer allows liquid penetration at We = 416; while a combination of five layers, as is the case of a commercially available N95 mask, blocks the penetration completely, consistent with the widely known effectiveness of N95 masks. Herein, we devote special attention to compare the so-obtained efficiency of N95 masks to that of a recently designed two-layer cloth mask containing an intermediate High-Efficiency Particulate Air (HEPA) filter layer (Narayan et al. in Phys Fluids 34:061703, 2022). We conclusively show that the performance of the designed cloth mask is identical to that of a commercially available N95 mask. The assessment of mask effectiveness further includes examination of breathability and comfort by means of passage of air through them. A comparative study has been presented herein for a clear demonstration of effectiveness of different masks in preventing air-borne transmission of COVID-19.

Detection of Porcine Deltacoronavirus RNA in the Upper and Lower Respiratory Tract and Biliary Fluid and the Effect of Infection on Serum Cholesterol Levels and Blood T Cell Population Frequencies in Gnotobiotic Piglets

Porcine deltacoronavirus (PDCoV) was first identified approximately a decade ago, but much is still obscure in terms of its pathogenesis. We aimed to further characterize PDCoV infection by investigating the presence of virus in respiratory and biliary tissues or fluids; T cell population frequencies in blood; and altered serum cholesterol levels. Twelve, 6-day-old, gnotobiotic piglets were inoculated oronasally with PDCoV OH-FD22 (2.6 × 107 FFU/pig). Six control piglets were not inoculated. Rectal swab (RS), nasal swab (NS), nasal wash (NW), bronchoalveolar lavage (BAL), and biliary fluid (BF) samples were collected at 2, 4, and 7 days post-inoculation (DPI) and tested for PDCoV RNA by RT-qPCR. Blood T cell populations and serum cholesterol levels were determined by flow cytometry and a colorimetric assay, respectively. Moderate to high, and low to moderate titers of PDCoV RNA were detected in RS and in NS, NW, BAL, and BF samples, respectively, of inoculated piglets. There were trends toward decreased CD4+CD8-, CD4-CD8+, and CD4+CD8+ blood T cell frequencies in inoculated piglets. Furthermore, serum cholesterol levels were increased in inoculated piglets. Overall, we found that PDCoV infection does not exclusively involve the intestine, since the respiratory and biliary systems and cholesterol metabolism also can be affected.

Liquid respiratory desaturation is a new method of preventing decompression sickness

Introduction. According to the literature data, the method of liquid ventilation for the prevention of decompression sickness (DCS) was proposed only with the condition of its initiation before compression, that excluded the physical basis of the disease - an excess of metabolically indifferent gas in the tissues. However, as the analysis shows, in most cases, the evacuation of the crew of an emergency submarine is aggravated by being in gases’ increased pressure environment. So the casualty tissues become obviously saturated with indifferent gas. Experimental confirmation of the possibility of rapid tissues’ desaturation of nitrogen during respiration by denitrogenizated and oxygenated in a normal conditions respiratory fluid (hereinafter - the method of liquid respiratory desaturation) was obtained on the biological model of DCS of Syrian hamsters. The study aim is an experimental substantiation of the possibility to use liquid respiratory desaturation as a method of preventing the development of decompression disorders. Materials and methods. Scientists have performed a study on 24 mature male Syrian hamsters weighing 165-185g, aged four months, using an experimental laboratory hyperbaric stand for temporary maintenance of small laboratory animals under high pressure of a gas or liquid medium with the possibility of switching from one medium to another in isobaric conditions.The research methodology is based on the assessment of the clinical presentation of decompression disorders and the results of ultrasound examination of gas formations in the heart, large veins and liver after the fast non-stop decompression, in the background of preliminary saturation of the animal's body with indifferent gas (nitrogen) by staying in the air under the pressure 0.6 MPa (60 MWC) for six hours. The effect on experimental groups animals deferens from the control group by the period of immersion and spontaneous breathing in the respiratory fluid (20, 30 and 40 minutes) before decompression. Results. The authors analyzed the clinical picture of acute decompression disorders. The degree of gas formation in small laboratory animals was assessed by researchers using ultrasound using a semi-quantitative method. Spontaneous breathing with the prepared liquid, lasting 30 minutes or more, made it possible to remove excess nitrogen from the body of animals of experimental groups, providing etiopathogenetic prevention of DCS before decompression. The article presents the data of morphological studies. Conclusion. Liquid respiratory desaturation is a method of preventing decompression disorders based on the removal of metabolically indifferent gases from the body during liquid respiration, in the presence of a stress gradient from tissues into the respiratory fluid. The method allows the metabolically indifferent gases' rapid desaturation from the body by liquid ventilation before/or during decompression, thereby creating conditions of ultra-fast decompression modes without the risk of decompression disorders.

ADVECTION AND DEPOSITION OF MICRODROPLETS IN STAGNATION POINT FLOW

We investigate trajectories of microscale evaporating droplets in a stagnation point flow near a wall of a respiratory airway. The configuration is motivated by the problem of advection and deposition of microscale droplets of respiratory fluids in human airways during transmission of infectious diseases, such as tuberculosis and COVID-19. Laminar boundary layer equations are solved to describe the airflow while the equations of motion of the droplet include contributions from gravity, aerodynamic drag, and Saffman force. Evaporation is accounted for at both the droplet surface and the wall of the respiratory airway and is shown to delay droplet deposition as compared to the predictions of isothermal models. Evaporation at the airway wall has a stronger effect on droplet trajectories than evaporation at the droplet surface, leading to droplets being advected away by the flow and thus avoiding deposition in the stagnation point flow region.

Face Masks and Prevention of Respiratory Viral Infections: An Overview

Airborne transmission of respiratory viruses consists of three sequential steps: (1) release of respiratory fluids in the form of droplets from the nose and mouth of an infected person, (2) transport of the droplets through air, and (3) entry of the droplets into the nose and mouth of an uninfected individual. Talking, coughing, and sneezing emit droplets across a spectrum of sizes. The water in exhaled droplets begins to evaporate in air and, as a result, the droplets are reduced in size shortly after being emitted. Face masks are effective for capturing droplets just released from the nose and mouth. Studies indicate that more than 50% of community transmission of SARS-CoV-2 is from asymptomatic and pre-symptomatic cases. Use of face masks by the public can effectively reduce the chance of infected individuals unknowingly spreading the virus. In addition to being an effective device for source control, face masks can protect the wearers from inhaling virus-laden droplets. Cloth masks and disposable masks provide reasonable protection for the public, while surgical masks and N95 respirators give higher levels of protection as needed in healthcare settings. Made with varied materials, these masks have different structural characteristics. The collection efficiency of a face mask depends on droplet size, face velocity, and the structural characteristics of the mask. For a given mask, capturing droplets is more effective during exhalation than during inhalation. Pressure drop across the mask should be taken into consideration when selecting a face mask. The best face mask is the one that gives the highest collection efficiency with the least pressure drop. For an effective protection, a mask should fit the face properly. While face masks have proven adequate in reducing airborne transmission of SARS-CoV-2 infections, continuous improvement is needed to better prepare for future respiratory viral threats.