Biomedical subjects

K Philipson

Publications and source records attributed to K Philipson.

75 records · Page 5Linked to original sources

PubMedDate not supplied

Human bronchiolar deposition and retention of 6-, 8- and 10-micrograms particles.

Three groups, each consisting of 6 healthy subjects, inhaled, respectively, 6-micrograms (aerodynamic diameter), 8-micrograms, and 10-micrograms Teflon particles, labeled with indium-111. The particles were inhaled at an extremely low flow rate, 0.05 L/s. Lung retention was measured after 0, 24, 48, and 72 h. Two models were used to calculate particle deposition in the lungs in the various generations: the Karolinska Institute model (KI model) and the University of Southampton model (US model). From the experimental clearance data and the theoretical deposition data, it was calculated that the average retention after 24 h was around 100% for particles deposited in generations 13-16 (ciliated bronchioles) and around 20% in generations 0-12 (both large and small ciliated airways). In these calculations, it was assumed that the retained fractions were independent of particle size. The depositions in the bronchial region (generations 0-8), bronchiolar region (generations 9-15 or 9-16), and the alveolar region were calculated using the two models and compared with the recent ICRP model. On the whole, the three models agreed fairly well.

Administration, Inhalation↗

PubMedDate not supplied

Effect of adrenergic stimulation on clearance from small ciliated airways in healthy subjects.

Mucociliary transport is an important clearance mechanism of larger airways, but in the smallest ciliated airways (bronchioles) it may be less effective. The present study aimed at investigating whether clearance from the bronchioles in subjects with healthy airways was stimulated by an adrenergic agonist (terbutaline sulphate). Tracheobronchial clearance was studied twice in 10 healthy subjects after inhalation of 6-micron (aerodynamic diameter) monodisperse Teflon particles labeled with 111In. At one exposure, oral treatment with terbutaline sulphate, known to stimulate clearance in large airways, began immediately after inhalation of the particles. The other exposure was a control measurement. The particles were inhaled at an extremely slow flow, 0.05 L/s, which gave deposition mainly in the small ciliated airways (bronchioles). Lung retention was measured at 0, 24, 48, and 72 h. Clearance was significant every 24 h for both exposures (p < .05, two-tailed paired t-test), with similar fractions of retained particles at all time points. During treatment with terbutaline sulphate, the subjects' pulse rates tended to be higher, but clearance rates did not increase. We found, as expected, no significant correlation between lung retention and lung function in either exposure. This study shows that an adrenergic agonist does not significantly influence overall clearance from the bronchiolar region in healthy subjects. This suggests that mucociliary transport does not significantly contribute to clearance from the smallest ciliated airways. Other mechanisms may be more important for the transportation of mucus from these airways.

Administration, Inhalation↗

PubMedDate not supplied

Retention of particles on the first bifurcation and the trachea of rabbits.

Retention of 6 micron, intratracheally-administered radioactively-tagged, teflon particles on the lower trachea and the first bifurcation of rabbits was measured externally for 2-3 days. Clearance occurred in a fast and a slow phase. The fast phase was finished after 1-2 h. The slow phase differed markedly between the lower trachea and the first bifurcation. The mean half-times were 19 and 39 h i trachea and first bifurcation, respectively. On average, 39% of the particles on the trachea and 71% on the first bifurcation cleared with the slow phase. Thus the bifurcation is more exposed to pollutants not only from deposition of more particles caused by impaction but also because of less efficient clearance.

Animals↗