Experimental measurements and computational predictions of regional particle deposition in a sectional nasal model.

Background: Knowledge of the regional deposition of inhaled particles in the nose is important for drug delivery and assessment of the toxicity of inhaled materials. In this study, computational fluid dynamics (CFD) predictions and experimental measurements in a nasal replica cast were used to study regional deposition of inhaled microparticles.

Methods: The replica cast was sectioned into six regions of interest based on nasal anatomy: the nasal vestibule, nasal valve, anterior turbinates, olfactory region, turbinates, and nasopharynx.

Inhalation dosimetry of hexamethylene diisocyanate vapor in the rat and human respiratory tracts.

Hexamethylene diisocyanate (HDI) is a reactive chemical used in the commercial production of polyurethanes. Toxic effects in rodents exposed to HDI vapor primarily occur in the nasal passages, yet some individuals exposed occupationally to concentrations exceeding current regulatory limits may experience temporary reduction in lung function and asthma-like symptoms. Knowledge of interspecies differences in respiratory tract dosimetry of inhaled HDI would improve our understanding of human health risks to this compound.

Inhaled carbon nanotubes reach the subpleural tissue in mice.

Carbon nanotubes are shaped like fibres and can stimulate inflammation at the surface of the peritoneum when injected into the abdominal cavity of mice, raising concerns that inhaled nanotubes may cause pleural fibrosis and/or mesothelioma. Here, we show that multiwalled carbon nanotubes reach the subpleura in mice after a single inhalation exposure of 30 mg m(-3) for 6 h. Nanotubes were embedded in the subpleural wall and within subpleural macrophages.

Interindividual variability in nasal filtration as a function of nasal cavity geometry.

Background: Interindividual variability in nasal filtration is significant due to interindividual differences in nasal anatomy and breathing rate. Two important consequences arise from this variation among humans. First, devices for nasal drug delivery may furnish quite different doses in the nasal passages of different individuals, leading to different responses to therapeutic treatment.

Inhaled multiwalled carbon nanotubes potentiate airway fibrosis in murine allergic asthma.

Carbon nanotubes are gaining increasing attention due to possible health risks from occupational or environmental exposures. This study tested the hypothesis that inhaled multiwalled carbon nanotubes (MWCNT) would increase airway fibrosis in mice with allergic asthma. Normal and ovalbumin-sensitized mice were exposed to a MWCNT aerosol (100 mg/m(3)) or saline aerosol for 6 hours.

Respiratory deposition and inhalability of monodisperse aerosols in Long-Evans rats.

Because of limitations on conducting exposure experiments using human subjects to evaluate adverse health effects, the deposition and fate of airborne particles in animals are often studied. The results of such studies are extrapolated to humans to estimate equivalent dose and subsequent response. In this article, particle inhalability and respiratory deposition of micron-size particles are determined for female Long-Evans rats.