A computer model for the simulation of nanoparticle deposition in the alveolar structures of the human lungs

Radiographic Phenotypes Affect the Risk of Inhaled Corticosteroid-Associated Pneumonia in Patients with COPD

Purpose

Few studies have reported the association between the radiographic characteristics and the development of pneumonia in patients with chronic obstructive pulmonary disease (COPD) treated with inhaled corticosteroids (ICSs). Our study aimed to assess the effect of radiographic phenotypes on the risk of pneumonia in patients treated with ICSs.

Patients and Methods

This study retrospectively analysed all patients with COPD treated with ICSs in a subset of the Korea Chronic Obstructive Pulmonary Disorders Subgroup Study registry between January 2017 and December 2019. The association between radiographic phenotypes including the presence and severity of emphysema, airway wall thickening, or bronchiectasis on chest computed tomography were determined visually/qualitatively and the risk of pneumonia was analyzed using the Cox regression model.

Results

Among the 90 patients with COPD treated with ICSs, 41 experienced pneumonia more than once during the median follow-up of 29 (interquartile range, 8–35) months. In univariate Cox regression analysis, older age, longer use of ICSs, use of fluticasone propionate or metered dose inhaler, and severe exacerbation events increased the risk of pneumonia. In multivariate analysis, the presence of emphysema (adjusted hazard ratio [aHR]=3.73, P=0.033), severity measured using the visual sum score (mild-to-moderate, aHR=8.58, P=0.016; severe, aHR=3.58, P=0.042), Goddard sum score (mild-to-moderate, aHR=3.31, P=0.058; severe, aHR=5.38, P=0.014), and the upper lobe distribution of emphysema (aHR=3.76, P=0.032) were associated with a higher risk of pneumonia. Subtypes of centrilobular and panlobular emphysema had a higher risk of pneumonia compared with paraseptal emphysema (aHR=3.98, P=0.033; HR=3.91, P=0.041 vs HR=2.74, P=0.304). The presence of bronchiectasis (aHR=2.41, P=0.02) and emphysema/bronchiectasis overlap phenotype (aHR=2.19, P=0.053) on chest CT was a risk factor for pneumonia in this population. However, severity of bronchiectasis and the presence or severity of bronchial wall thickening according to the visual sum score were not associated with the risk of pneumonia.

Conclusion

Among patients with COPD treated with ICSs, radiographic phenotypes including the presence of emphysema, bronchiectasis or emphysema/bronchiectasis overlap phenotype, severity with emphysema, subtypes of centrilobular or panlobular emphysema, and upper lobe distribution of emphysema may help predict the risk of pneumonia.

A Review of Respiratory Anatomical Development, Air Flow Characterization and Particle Deposition

The understanding of complex inhalation and transport processes of pollutant particles through the human respiratory system is important for investigations into dosimetry and respiratory health effects in various settings, such as environmental or occupational health. The studies over the last few decades for micro- and nanoparticle transport and deposition have advanced the understanding of drug-aerosol impacts in the mouth-throat and the upper airways. However, most of the Lagrangian and Eulerian studies have utilized the non-realistic symmetric anatomical model for airflow and particle deposition predictions. Recent improvements to visualization techniques using high-resolution computed tomography (CT) data and the resultant development of three dimensional (3-D) anatomical models support the realistic representation of lung geometry. Yet, the selection of different modelling approaches to analyze the transitional flow behavior and the use of different inlet and outlet conditions provide a dissimilar prediction of particle deposition in the human lung. Moreover, incorporation of relevant physical and appropriate boundary conditions are important factors to consider for the more accurate prediction of transitional flow and particle transport in human lung. This review critically appraises currently available literature on airflow and particle transport mechanism in the lungs, as well as numerical simulations with the aim to explore processes involved. Numerical studies found that both the Euler–Lagrange (E-L) and Euler–Euler methods do not influence nanoparticle (particle diameter ≤50 nm) deposition patterns at a flow rate ≤25 L/min. Furthermore, numerical studies demonstrated that turbulence dispersion does not significantly affect nanoparticle deposition patterns. This critical review aims to develop the field and increase the state-of-the-art in human lung modelling.

Non-Lamellar Lyotropic Liquid Crystalline Lipid Nanoparticles for the Next Generation of Nanomedicine

Nonlamellar lyotropic liquid crystalline (LLC) lipid nanomaterials have emerged as a promising class of advanced materials for the next generation of nanomedicine, comprising mainly of amphiphilic lipids and functional additives self-assembling into two- and three-dimensional, inverse hexagonal, and cubic nanostructures. In particular, the lyotropic liquid crystalline lipid nanoparticles (LCNPs) have received great interest as nanocarriers for a variety of hydrophobic and hydrophilic small molecule drugs, peptides, proteins, siRNAs, DNAs, and imaging agents. Within this space, there has been a tremendous amount of effort over the last two decades elucidating the self-assembly behavior and structure-function relationship of natural and synthetic lipid-based drug delivery vehicles in vitro, yet successful clinical translation remains sparse due to the lack of understanding of these materials in biological bodies. This review provides an overview of (1) the benefits and advantages of using LCNPs as drug delivery nanocarriers, (2) design principles for making LCNPs with desirable functionalities for drug delivery applications, (3) current understanding of the LLC material-biology interface illustrated by more than 50 in vivo, preclinical studies, and (4) current patenting and translation activities in a pharmaceutical context. Together with our perspectives and expert opinions, we anticipate that this review will guide future studies in developing LCNP-based drug delivery nanocarriers with the objective of translating them into a key player among nanoparticle platforms comprising the next generation of nanomedicine for disease therapy and diagnosis.

Characterizing risk assessments for the development of occupational exposure limits for engineered nanomaterials

The commercialization of engineered nanomaterials (ENMs) began in the early 2000's. Since then the number of commercial products and the number of workers potentially exposed to ENMs is growing, as is the need to evaluate and manage the potential health risks. Occupational exposure limits (OELs) have been developed for some of the first generation of ENMs. These OELs have been based on risk assessments that progressed from qualitative to quantitative as nanotoxicology data became available. In this paper, that progression is characterized. It traces OEL development through the qualitative approach of general groups of ENMs based primarily on read-across with other materials to quantitative risk assessments for nanoscale particles including titanium dioxide, carbon nanotubes and nanofibers, silver nanoparticles, and cellulose nanocrystals. These represent prototypic approaches to risk assessment and OEL development for ENMs. Such substance-by-substance efforts are not practical given the insufficient data for many ENMs that are currently being used or potentially entering commerce. Consequently, categorical approaches are emerging to group and rank ENMs by hazard and potential health risk. The strengths and limitations of these approaches are described, and future derivations and research needs are discussed. Critical needs in moving forward with understanding the health effects of the numerous EMNs include more standardized and accessible quantitative data on the toxicity and physicochemical properties of ENMs.

[Progress in numerical simulation and experimental study on inhalable particles deposition in human respiratory system]

Inhalable particles deposition in the human respiratory system is the main cause of many respiratory and cardiovascular diseases. It plays an important role in related disease prevention and treatment through establishing computer or external entity models to study rules of particle deposition. The paper summarized and analyzed the present research results of various inhalable particle deposition models of upper respiratory tract and pulmonary area, and expounded the application in the areas of disease inducement analysis, drug inhale treatment etc. Based on the review, the paper puts forward the problems and application limitations of present research, especially pointing out future emphasis in development directions. It will have a value of reference guidance for further systematic and in-depth study on the inhalable particle deposition simulation, experiment and application.

Influence of Nanotoxicity on Human Health and Environment: The Alternative Strategies

Currently, nanotechnology revolutionizing both scientific and industrial community due to their applications in the fields of medicine, environmental protection, energy, and space exploration. Despite of the evident benefits of nanoparticles, there are still open questions about the influence of these nanoparticles on human health and environment. This is one of the critical issues that have to be addressed in the near future, before massive production of nanomaterials. Manufactured nanoparticles, which are finding ever-increasing applications in industry and consumer products fall into the category of emerging contaminants with ecological and toxicological effects on populations, communities and ecosystems. The existing experimental knowledge gave evidence that inhaled nanoparticles are less efficiently separated than larger particles by the macrophage clearance mechanisms and these nanoparticles are known to translocate through the lymphatic, circulatory and nervous systems to many tissues and organs, including the brain. In this review we highlight adverse impacts of nanoparticles on human and the environment with special emphasis on green nanoscience as a sustainable alternative.

Theoretical diagnosis of emphysema by aerosol bolus inhalation

BACKGROUND

The present contribution deals with the theoretical description of aerosol bolus dispersion in lungs being affected by different manifestations of emphysema. The work constructs the hypothesis that each manifestation of emphysema exhibits specific properties with regard to the dispersion of inhaled and exhaled aerosol boluses as well as the deposition of particles from the aerosol pulse.

METHODS

For an appropriate simulation of single emphysematous manifestations, a previously developed model assuming (I) a random variation of alveolar diameters, (II) an exact localization of diseased structures, and (III) a realistic balance between alveolar air volume and number of air sacs was applied. Dispersion of inhaled and exhaled aerosol boluses was simulated by using the mathematical concept of effective diffusivities. Computations were conducted for an average adult lung (FRC =3,300 mL), symmetric breath-cycles with a length 8 s, and inhalation flow rates of 250 mL/s. Particles used for the model predictions had a uniform diameter of 0.84 µm and a density of 1 g/cm³.

RESULTS

According to the theoretical data obtained from the model highest aerosol bolus dispersion may be observed in lungs affected by panacinar and bullous emphysema, whereas centriacinar and paraseptal emphysema cause a significant reduction of the phenomenon. Also other statistical parameters exhibit partly remarkable differences among the studied manifestations. Particle deposition in lungs affected by bullous emphysema falls below that of lungs impaired by the other types of emphysema by 2%-50%.

CONCLUSIONS

From the hypothetical results presented in this study it may be concluded that aerosol bolus inhalation bears a certain potential for the diagnosis of emphysematous structures and, if applied with sufficient accuracy, also for the distinction of single manifestations of emphysema. For a successful use of the technique, however, all statistical bolus parameters and particle deposition have to be subjected to a detailed evaluation.