Explore the vast range of titles available.

BackgroundGlobally, a large percentage of men keep a beard at least occasionally. Workplace regulations prohibit beards with N95 respirators, but there is little information on the effect of beards with face masks worn by the public for protection against SARS-CoV-2.Methods and findingsWe examined the fitted filtration efficiency (FFE) of five commonly worn protective face masks as a function of beard length following the US Occupational Safety and Health Administration Quantitative Fit Test: N95 (respirator), KF94 and KN95, surgical/procedure, and cloth masks. A comparison using N95 respirators was carried out in shaven and bearded men. A detailed examination was conducted for beard lengths between 0 and 10 mm (0.5 mm increments). The effect of an exercise band covering the beard on FFE was also tested. Although N95 respirators showed considerable variability among bearded men, they had the highest FFE for beard lengths up to 10 mm. KF94 and KN95 masks lost up to 40% of their FFE. Procedure and cotton masks had poor performance even on bare skin (10–30% FFE) that did not change appreciably with beard length. Marked performance improvements were observed with an exercise band worn over the beard.ConclusionsThough variable, N95 respirators offer the best respiratory protection for bearded men. While KF94 and KN95 FFE is compromised considerably by increasing beard length, they proved better options than procedure and cotton face masks. A simple exercise band improves FFE for face masks commonly used by bearded men during the COVID-19 pandemic.

Abstract Rationale Chronic bronchitis (CB) is characterized by persistent cough and sputum production. Studies were performed to test whether mucus hyperconcentration and increased partial osmotic pressure, in part caused by abnormal purine nucleotide regulation of ion transport, contribute to the pathogenesis of CB. Objectives We tested the hypothesis that CB is characterized by mucus hyperconcentration, increased mucus partial osmotic pressures, and reduced mucus clearance. Methods We measured in subjects with CB as compared with normal and asymptomatic smoking control subjects indices of mucus concentration (hydration; i.e., percentage solids) and sputum adenine nucleotide/nucleoside concentrations. In addition, sputum partial osmotic pressures and mucus transport rates were measured in subjects with CB. Measurements and Results CB secretions were hyperconcentrated as indexed by an increase in percentage solids and total mucins, in part reflecting decreased extracellular nucleotide/nucleoside concentrations. CB mucus generated concentration-dependent increases in partial osmotic pressures into ranges predicted to reduce mucus transport. Mucociliary clearance (MCC) in subjects with CB was negatively correlated with mucus concentration (percentage solids). As a test of relationships between mucus concentration and disease, mucus concentrations and MCC were compared with FEV1, and both were significantly correlated. Conclusions Abnormal regulation of airway surface hydration may slow MCC in CB and contribute to disease pathogenesis.

Abstract Background: The site of deposition in the respiratory tract for aerosolized, inhaled therapeutic drugs depends on both the particles' aerodynamic size and the patient's breathing pattern. Methods: In 21 healthy subjects with normal lung function, we evaluated an extremely slow inhalation of a large 9.5-μm MMAD particle aerosol (ESI-9) for its ability to enhance the delivery of radiolabeled particles (99mTc-labeled sulfur colloid) to the conducting airways. The regional deposition of the large particles (modified Pari-Boy jet nebulizer), inhaled at the extremely low rate of 0.080 Lps for 10 sec, was compared to the deposition of 5-μm MMAD particles inhaled during cyclic resting tidal breathing (TVB-5-) (mean 0.44 L and 0.46 Lps). Gamma scintigraphy gave an estimate of conducting airway deposition (% CAD) as a fraction of all deposited particles by multiplying the percent of activity in both lungs immediately postdeposition relative to the total deposition (i.e., lungs + mouth + esophagus + stomach) times the percent of activity cleared from the lungs over 24 h. Results: % CAD for healthy subjects for the ESI-9 and TVB-5 maneuvers was 35% (±8%) and 27% (±11%), respectively, p = 0.004). The amount deposited within the oropharynx was 26% (±7%) and 37% (±11%), respectively, p < 0.001. Conclusions: Higher therapeutic value of a medication delivered to the conducting airways where the primary defect is associated with many diseases, and with fewer losses to the extrathoracic surfaces, may be obtained by using an “extremely slow inhalation and large particle” routine when compared to a normal tidal volume breathing associated with typical nebulizers.

Face masks reduce disease transmission by protecting the wearer from inhaled pathogens and reducing the emission of infectious aerosols. Although methods quantifying efficiency for wearer protection are established, current methods for assessing face mask containment efficiency rely on measurement of a low concentration of aerosols emitted from an infected or noninfected individual. A small port enabled the introduction of 0.05 µm sodium chloride particles at a constant rate behind the mask worn by a study participant. A condensation particle counter monitored ambient particle numbers 60 cm in front of the participant over 3-minute periods of rest, speaking, and coughing. The containment efficiency (%) for each mask and procedure was calculated as follows: 100 × (1 - average ambient concentration with face covering worn/average ambient concentration with a sham face covering in place). The protection efficiency (%) was also measured using previously published methods. The probability of transmission (%) from infected to uninfected (a function of both the containment efficiency and the protection efficiency) was calculated as follows: {1 - (containment efficiency/100)}×{1 - (protection efficiency/100)}×100. The average containment efficiencies for each mask over all procedures and repeated measures were 94.6%, 60.9%, 38.8%, and 43.2%, respectively, for the N95 mask, the KN95 mask, the procedure face mask, and the gaiter. The corresponding protection efficiencies for each mask were 99.0%, 63.7%, 45.3%, and 24.2%, respectively. For example, the transmission probability for 1 infected and 1 uninfected individual in close proximity was ∼14.2% for KN95 masks, compared to 36%-39% when only 1 individual wore a KN95 mask. Overall, we detected a good correlation between the protection and containment that a face covering afforded to a wearer.

Inhalation of hypertonic saline has a modest beneficial effect on lung function and the frequency of exacerbations in patients with cystic fibrosis. In this article, the investigators provide in vivo and in vitro data suggesting that this therapeutic effect derives from sustained acceleration of mucus clearance. The investigators provide in vivo and in vitro data suggesting that the therapeutic effect of inhaled hypertonic saline derives from sustained acceleration of mucus clearance. Mucus clearance defends the lung against inhaled bacteria. The efficiency of mucus clearance depends on an adequate volume of airway surface liquid (i.e., hydration). 1 One hypothesis for the pathogenesis of lung disease in patients with cystic fibrosis is that a lack of regulation of sodium absorption and chloride secretion causes depletion of airway surface liquid, slows mucus clearance, and promotes the formation of adherent mucus plaques on airway surfaces. Mucus plaques and plugs obstruct airways and provide the nidus for infection. 2 , 3 On the basis of this hypothesis, therapies that increase the volume of airway surface liquid, and hence mucus . . .

Background: Recent studies show e-cigarette (EC) users have increased rates of chronic bronchitic symptoms that may be associated with depressed mucociliary clearance (MCC). Little is known about the acute or chronic effects of EC inhalation on in vivo MCC. Methods: In vivo MCC was measured in young adult vapers ( n  = 5 males, mean age = 21) after controlled inhalation of a radiolabeled (Tc99m sulfur colloid) aerosol. Whole-lung clearance of radiolabeled deposited particles was measured over a 90-minute period for baseline MCC and associated with controlled periodic vaping over the first 60 minutes of MCC measurements. The vaping challenge was administered from a fourth generation box mod EC containing unflavored e-liquid (65% propylene glycol/35% vegetable glycerin, 3 mg/mL freebase nicotine). The challenge was administered at the start of each 10-minute interval of MCC measurements and consisted of 1 puff every 30 seconds for 5 minutes (i.e., 10 puffs for each 10-minute period for a total of 60 puffs during the initial 60 minutes of MCC measurements). Results: Compared with baseline, peripheral lung average clearance (%) over the 90 minutes of MCC measures was enhanced, associated with EC challenge, 12 (±6) versus 24 (±6), respectively ( p  < 0.05 by Wilcoxon signed-rank test). Conclusions: Acute enhancement of in vivo MCC during EC challenge is contrary to recent studies showing nicotine-associated slowing of ciliary beat and mucus transport at higher nicotine levels than those used here. However, our findings are consistent with an acute increase in fluid volume and mucin secretion to the bronchial airway surface that is likely short lived. Research reported in this publication was supported by the National Institutes of Health R01HL139369 and registered with ClinicalTrials.gov (NCT03700892).

Abstract Two-dimensional (2D or planar) imaging with 99mTc radiolabels enables quantification of whole-lung and regional lung depositions for orally inhaled drug products. This article recommends standardized methodology for 2D imaging studies. Simultaneous anterior and posterior imaging with a dual-headed gamma camera is preferred, but imaging with a single-headed gamma camera is also acceptable. Correction of raw data for the effects of gamma ray attenuation is considered essential for accurate quantification, for instance, using transmission scanning with a flood-field source of 99mTc or 57Co. Evidence should be provided of the accuracy of the quantification method, for instance, by determining “mass balance.” Lung deposition may be expressed as a percentage of ex-valve or ex-device dose, but should also be given as mass of drug when possible. Assessment of regional lung deposition requires delineation of the lung borders, using X-ray computed tomography, radioactive gas scans (133Xe or 81mKr), or transmission scans. When quantifying regional lung deposition, the lung should be divided into outer (O) and inner (I) zones. A penetration index should be calculated, as the O/I ratio for aerosol, normalized to that for a radioactive gas or transmission scan. A variety of methods can be used to assess lung deposition and distribution. Methodology and results should be documented in detail, so that data from different centers may be compared. The use of appropriate methodology will provide greater confidence in the results of 2D imaging studies, and should allay concerns that such studies are qualitative or semiquantitative in nature.

Abstract Background: Electronic cigarettes (ECIGs) are widely used, but their health effects are not well known. ECIG exposure is difficult to quantify, and a direct measurement of deposition would be beneficial to in vivo and in vitro toxicity studies. The aim of this study was to demonstrate effective radiolabeling of an ECIG. Methods: A technetium-99m-labeled carbon ultrafine (TCU) aerosol was generated and introduced to a fourth-generation ECIG before nucleation and aerosol formation. The aerosolized e-liquid was a commercially available strawberry flavor containing 1.2% nicotine in a 55% propylene glycol and 45% vegetable glycerine base. An ECIG power setting of 100 W was selected. Mass and radioactivity were measured on each stage within a Sierra Cascade Impactor at 14 L/min to verify the labeling technique using the calculated aerodynamic diameters. A strong positive correlation (R2 > 0.95) between the percent activity and percent mass deposition on each stage provides a reliable validation of colocation. Results: Unlabeled ECIG aerosol from the chosen e-liquid produced a mass median aerodynamic diameter (MMAD) of 0.85 μm. An ECIG labeled with TCU produced an aerosol with an activity median aerodynamic diameter of 0.84 μm and an MMAD of 0.84 μm. The relative mass versus radioactivity on each plate was highly correlated (average R2 = 0.973, p < 0.001). Conclusion: A TCU radiolabel was generated and shown to associate with the mass of an aerosol produced by a typical commercially available ECIG. Thus, the radioactivity of the deposited aerosol may be used to determine ECIG aerosol deposition for the future in vivo and in vitro dosimetry studies of the third- and fourth-generation ECIGs.

Abstract Background: Understanding the regional partition of deposition of inhaled particles within the lung is important for improving targeted delivery of inhaled aerosolized drugs. One factor affecting regional deposition is gravity. As the lung deforms under its own weight, changes in lung volume, in airway geometries, and in spatial patterns of ventilation distribution between postures have the potential to alter the regional distribution of deposited particles. Methods: Using gamma-scintigraphy, we measured regional deposition and clearance of 99mTc labeled particles (5 μm) in 6 healthy subjects, with aerosol inhalation occurring both in the supine and seated postures at constant flow (0.5 L/sec) and breathing rate (15 breaths/min). After aerosol deposition, mucociliary clearance data were collected in the seated posture, immediately post-particle administration, 1 h 30 min, 4 h, and 22 h post-inhalation. Relative regional deposition was computed using retention (R) at the different time points, with (1-R1h30min), (R1h30min- R4h), and (R4h- R22h) corresponding to deposition in the large, intermediate, and small airways, respectively. Alveolar deposition was estimated as the relative retention at 22 h (R22h). Results: Relative deposition of coarse particles in the alveolar region decreased from 60±8% seated to 34±16% supine (p=0.04). This change was accompanied by an increase in relative deposition in the intermediate (7±3% seated to 16±17% supine, P=0.09) and small airways (19±6% seated to 34±13% supine, p=0.06) when inhalation occurred in the supine posture. No change was observed in central to peripheral deposition (C/P ratio), the skew of the deposition distribution, or the apex-to-base ratio of deposition between seated and supine postures. Conclusions: Inhalation of coarse particles in the supine posture shifts relative deposition from the alveolar to the bronchial airways, when compared to the seated posture, likely driven by changes in functional residual capacity, and airway size, as well as changes in the regional distribution of ventilation between postures.

Abstract Background: To quantify the relationship between regional lung ventilation and coarse aerosol deposition in the supine healthy human lung, we used oxygen-enhanced magnetic resonance imaging and planar gamma scintigraphy in seven subjects. Methods: Regional ventilation was measured in the supine posture in a 15 mm sagittal slice of the right lung. Deposition was measured by using planar gamma scintigraphy (coronal scans, 40 cm FOV) immediately postdeposition, 1 hour 30 minutes and 22 hours after deposition of 99mTc-labeled particles (4.9 μm MMAD, GSD 2.5), inhaled in the supine posture (flow 0.5 L/s, 15 breaths/min). The distribution of retained particles at different times was used to infer deposition in different airway regions, with 22 hours representing alveolar deposition. The fraction of total slice ventilation per quartile of lung height from the lung apex to the dome of the diaphragm at functional residual capacity was computed, and co-registered with deposition data—apices aligned—using a transmission scan as reference. The ratio of fractional alveolar deposition to fractional ventilation of each quartile (r) was used to evaluate ventilation and deposition matching (r > 1, regional aerosol deposition fraction larger than regional ventilation fraction). Results: r was not significantly different from 1 for all regions (1.04 ± 0.25, 1.08 ± 0.22, 1.03 ± 0.17, 0.92 ± 0.13, apex to diaphragm, p > 0.40) at the alveolar level (r22h). For retention times r0h and r1h30, only the diaphragmatic region at r1h30 differed significantly from 1. Conclusions: These results support the hypothesis that alveolar deposition is directly proportional to ventilation for ∼5 μm particles that are inhaled in the supine posture and are consistent with previous simulation predictions that show that convective flow is the main determinant of aerosol transport to the lung periphery.