Voxel-based simulation of flow and temperature in the human nasal cavity.

The nasal airway is an extremely complex structure, therefore grid generation for numerical prediction of airflow in the nasal cavity is time-consuming. This paper describes the development of a voxel-based model with a Cartesian structured grid, which is characterized by robust and automatic grid generation, and the simulation of the airflow and air-conditioning in an individual human nasal airway. Computed tomography images of a healthy adult nose were used to reconstruct a virtual three-dimensional model of the nasal airway.

Voxel-based modeling of airflow in the human nasal cavity.

This paper describes the simulation of airflow in human nasal airways using voxel-based modeling characterized by robust, automatic, and objective grid generation. Computed tomography scans of a healthy adult nose are used to reconstruct 3D virtual models of the nasal airways. Voxel-based simulations of restful inspiratory flow are then performed using various mesh sizes to determine the level of granularity required to adequately resolve the airflow.

Murine pulmonary acinar mechanics during quasi-static inflation using synchrotron refraction-enhanced computed tomography.

We visualized pulmonary acini in the core regions of the mouse lung in situ using synchrotron refraction-enhanced computed tomography (CT) and evaluated their kinematics during quasi-static inflation. This CT system (with a cube voxel of 2.8 μm) allows excellent visualization of not just the conducting airways, but also the alveolar ducts and sacs, and tracking of the acinar shape and its deformation during inflation.

Lung injury similar to blast lung in a case of shotgun wound of the head.

Primary blast lung injury after explosions has been well described in the literature. A case of injury to the lung, after a shotgun wound to the head, similar to primary blast lung, is presented. Histological appearances of the lung revealed alveolar over distension, rupture and intra-alveolar hemorrhage.

Nasal inspiratory flow: at rest and sniffing.

Background: This study quantifies the time-varying flow rate during inspiration at rest and in sniffing, both predecongestion and postdecongestion. It aims to provide a better understanding of nasal airflow mechanics, for application to the physiological modeling of nasal respiration and to therapeutic drug delivery.

Methods: The temporal profiles of nasal inspiration were measured at high fidelity in 14 healthy individuals using simultaneous bilateral hot-wire anemometry.

Forensic implications of respiratory derived blood spatter distributions.

The nature of blood aerosols produced in physiological studies of an upright subject expiring small volumes through straws, spitting and mouthing sounds, and a semi-prone subject spitting through a bloody mouth or snorting through a single nasal orifice and by a simplified physical model of the respiratory system were investigated. Each manoeuvre produced many hundreds of droplets of a range of size, the vast majority being less than 1mm diameter. Droplets under 1mm dia.

Effect of acute airway inflammation on the pulmonary antioxidant status.

Effects of acute airway inflammation induced by organic dust inhalation on pulmonary antioxidant status were investigated in healthy horses and horses affected by recurrent airway obstruction. Exposure to organic dust induced acute airway neutrophilia, which was associated with increases in elastase and decreases in ascorbic acid concentrations in bronchoalveolar lavage fluid. However, markers of oxidative stress were unaffected, as was hydrogen peroxide in breath condensate.

Breath condensate hydrogen peroxide correlates with both airway cytology and epithelial lining fluid ascorbic acid concentration in the horse.

The relationship between hydrogen peroxide (H2O2) concentration in expired breath condensate (EBC) and cytology of the respiratory tract obtained from tracheal wash (TW) or bronchoalveolar lavage (BAL), and epithelial lining fluid (ELF) antioxidant status is unknown. To examine this we analysed the concentration of H2O2 in breath condensate from healthy horses and horses affected by recurrent airway obstruction (RAO), a condition considered to be an animal model of human asthma. The degree of airway inflammation was determined by assessing TW inflammation as mucus, cell density and neutrophil scores, and by BAL cytology.

Human corticospinal excitability in microgravity and hypergravity during parabolic flight.

Introduction: Spontaneous electromyographic (EMG) activity in the soleus muscle of the rat varies with the changing gravitational force in parabolic flight, presumably in an appropriate way to resist the load. We investigated how decreased and increased gravitational force affects EMG in human back and arm muscles and to what extent the motor cortex is responsible for any modulation seen.

Methods: Three healthy subjects stood during 10 parabolas consisting of periods (duration 20-25 s) of 1.

Air-conditioning characteristics of the human nose.

Nasal inspiration is important for maintaining the internal milieu of the lung, since ambient air is conditioned to nearly alveolar conditions (body temperature and fully saturated with water vapour) upon reaching the nasopharynx. This literature review of the existing in vivo, in vitro and computational studies on transport phenomena that take place within the human nasal cavity summarizes the current knowledge on air-conditioning characteristics of the human nose.

Localized compliance of small airways in excised rat lungs using microfocal X-ray computed tomography.

Airway compliance is a key factor in understanding lung mechanics and is used as a clinical diagnostic index. Understanding such mechanics in small airways physiologically and clinically is critical. We have determined the "morphometric change" and "localized compliance" of small airways under "near"-physiological conditions; namely, the airways were embedded in parenchyma without dehydration and fixation.

Pulmonary epithelial lining fluid and plasma ascorbic acid concentrations in horses affected by recurrent airway obstruction.

Objective: To determine the pulmonary epithelial lining fluid (ELF) concentrations and degree of oxidation of ascorbic acid in horses affected by recurrent airway obstruction (RAO) in the presence and absence of neutrophilic airway inflammation.

Animals: 6 RAO-affected horses and 8 healthy control horses.

Procedure: Nonenzymatic antioxidant concentrations were determined in RBC, plasma, and ELF samples of control horses and RAO-affected horses in the presence and absence of airway inflammation.

Three-dimensional visualization and morphometry of small airways from microfocal X-ray computed tomography.

Physiological morphometry is a critical factor in the flow dynamics in small airways. In this study, we visualized and analyzed the three-dimensional structure of the small airways without dehydration and fixation. We developed a two-step method to visualize small airways in detail by staining the lung tissue with a radiopaque solution and then visualizing the tissue with a cone-beam microfocal X-ray computed tomographic (CT) system.

Pulmonary bioavailability of ascorbic acid in an ascorbate-synthesising species, the horse.

Vitamin C (ascorbic acid) is a non-enzymatic antioxidant important in protecting the lung against oxidative damage and is decreased in lung lining fluid of horses with airway inflammation. To examine possible therapeutic regimens in a species with ascorbate-synthesising capacity, we studied the effects of oral supplementation of two forms of ascorbic acid, (each equivalent to 20 mg ascorbic acid per kg body weight) on the pulmonary and systemic antioxidant status of six healthy ponies in a 3 x 3 Latin square design. Two weeks supplementation with ascorbyl palmitate significantly increased mean plasma ascorbic acid concentrations compared to control (29 +/- 5 and 18 +/- 7 micromol/l, respectively; p < 0.