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D B Yeates

Publications and source records attributed to D B Yeates.

64 records · Page 4Linked to original sources
PubMed1975

Factors affecting tracheobronchial mucociliary transport.

In vivo mucus transport rates were studied in humans and donkeys by external measurement of the rate of clearance of insoluble monodisperse gamma-tagged aerosols. The influence of temperature, environmental toxicants and drugs which affect the autonomic nervous system were studied by determining the changes in clearance produced by them in individual subjects. In donkeys, increased pretest ambient temperature accelerated clearance by greater than 1.7%/ degrees C. Smoking 2-7 cigarettes reduced the duration of bronchial clearance by approximately 50% in both humans and donkeys. Donkeys were exposed to higher doses; with progressive slowing of tracheal and bronchial clearance for greater than 10 cigarettes. HCN, at concentrations up to 1230 ppm, produced only a mild transient slowing of clearance. In man, atropine slowed clearance, while the adrenergic stimulating drugs, isoproterenol and epinephrine, both accelerated it by greater than or equal to 4 times, as did isoproterenol when given subsequent to atropine. The cholinergic stimulating drug methacholine increased mucociliary transport in the the donkey. Administration of a tap water aerosol for 10-15 min in humans increased bronchial clearance rates by approximately 25%.

Aerosols↗
PubMedDate not supplied

Analysis of aerosol deposition in the healthy human lung.

Wide variation in the pattern of deposition of inhaled aerosols has previously been described in both healthy and diseased humans. To investigate the factors responsible for such variation, the authors studied a group of 13 healthy nonsmoking subjects. One two occasions each subject inhaled a monodisperse 8.1 mm (mass median aerodynamic diameter) Fe2O3 aerosol labelled with 99mTc using a standardized breathing pattern. Pulmonary function was defined by tests of forced expiratory airflow. Total activity in the right lung at 0 hr and at 24 hr (24-hr percent retention) was measured using a gamma camera. Numerical indices of deposition pattern were derived in several ways from the initial gamma camera image of the right lung by comparing the ratio of activity within a mid- and peripheral lung region of interest, by analyzing the profile of radioactivity within a horizontal band across the right lung from the midline to the lung edge, and by analysis of a distribution histogram of activity within the whole lung (skew and kurtosis). The 24-hr percent retention of aerosol showed considerable intrasubject variability unlike the deposition indices. The various deposition indices were found to correlate with the 24-hr percent retention, FEV1.0, FEV1.0/FVC%, and MMFR at varying levels of significance. Results indicate that the pattern of aerosol deposition in healthy humans is influenced by mild degrees of obstruction to airflow, as reflected by tests of forced expiratory airflow, increasing airways obstruction being associated with more central deposition of the inhaled aerosol. Deposition indices derived from the initial pattern of aerosol distribution within the lung may prove to be more reliable and sensitive than measurements of 24-hr percent retention in defining aerosol deposition pattern.

Adult↗
PubMedDate not supplied

Response of human mucociliary clearance to acute alcohol administration.

To determine whether alcohol inhibits mucociliary clearance in humans, the clearance of deposited radiolabelled particles from the lung was measured in 12 volunteers. On one study day, immediately after inhalation of aerosol, the subject ingested ethyl alcohol (0.5 g/kg) in orange juice producing an average alcohol level at 1 hr of 68 +/- 8 mg/kl. On the other study day, orange juice alone was ingested. The initial deposition of aerosol and sequential measurements of lung retention were made during 4.7 hr and again at 24 hr using a gamma camera. Aerosol deposition patterns were reproducible within subjects. Group average percent bronchial retention during a 4.5-hr period was not significantly different between the control and the alcohol studies, but the variance in the alcohol studies during 0.5-4.5 hr was significantly greater (P less than .001). Comparison of data to a previous study group of matched control subjects confirmed an increased variability in clearance after alcohol. Thus, acute alcohol ingestion, at levels similar to those achieved during social drinking, alters mucociliary clearance, but direction and magnitude of the changes differ among individuals.

Adult↗
PubMedDate not supplied

The effects of acute respiratory virus infection upon tracheal mucous transport.

Tracheal mucous velocity was measured in 13 healthy non-smokers using a radioisotope-labeled aerosol and a multidetector probe during respiratory virus infections. The movement of boluses of tracheal mucous were either absent or reduced in number in five subjects with myxovirus infection (four influenza and one respiratory syncytial virus) within 48 hr of the onset of symptoms and in four subjects 1 wk later. One subject with influenza still had reduced bolus formation 12-16 wk after infection. Frequent coughing was a feature of those subjects with absent tracheal boluses. In contrast, four subjects with rhinovirus infection had normal tracheal mucous velocity at 48 hr after the onset of symptoms (4.1 +/- 1.3 mm/min). Tracheal mucous velocity was also normal (4.6 +/- 1.1 mm/min) in four subjects in whom no specific viral agent could be defined but of respiratory viral infection. During health tracheal mucous velocity was (4.8 +/- 1.6 mm/min) in the eleven subjects who had measurements made. Disturbances in tracheal mucous transport during virus infection appear to depend upon the type of virus and are most severe in influenza A and respiratory syncytial virus infection.

Adult↗
PubMedDate not supplied

The relationships of aerosol deposition, lung size, and the rate of mucociliary clearance.

Although the effect of deposition pattern of an inhaled aerosol upon subsequent mucociliary clearance is well recognized, the influence of lung size on the rate of clearance has not been clearly defined. To examine the relationships of lung size in terms of the forced vital capacity (FVC) and aerosol deposition pattern to the rate of mucociliary clearance, we measured lung retention of an inhaled 8-micron aerosol for 120 min using a gamma camera in 13 healthy nonsmoking volunteers. The deposition pattern of the inhaled aerosol was defined in terms of the initial skew of the distribution of retained activity within the right lung (skew) and the percent retained at 24 hr (R24). Multiple regression analysis showed that FVC was responsible for approximately 36% of the variability in bronchial retention with time, with a lesser contribution from variations in deposition pattern (skew and R24). Mucociliary clearance was significantly slower (i.e., greater bronchial retention) in male subjects than in female subjects which can probably be attributed to the differences in FVC. Variations in lung sizes as well as deposition pattern should therefore be considered when making between subject comparisons of the mucociliary clearance rate.

Adult↗
PubMedDate not supplied

Mucociliary clearance of deposited particles from the human lung: intra- and inter-subject reproductivity, total and regional lung clearance, and model comparisons.

The intra- and inter-subject reproducibility of pulmonary mucociliary clearance was investigated in nine healthy male subjects following deposition of an aerosol of 7.9 microns aerodynamic diameter iron oxide particles labeled with TC-99m. The results have been analyzed for both total bronchial clearance and for clearance from areas representing central (Zone I), mid (Zone II), and peripheral (Zone III) regions of the lung. The observed clearance rates were compared to the predictions of a mathematical model for lung clearance based on Weibel's dicotomous branching system. The results for total bronchial clearance showed an average TB120 (percent cleared in 2 hr) of 57%, while the average TB120 for Zone I, II, and III was 56%, 62%, and 48%, respectively. The mean half-times (times required to clear 50% of the deposited activity) for the total bronchial clearance and for Zones I, II, and III were 1.90 hr, 1.97 hr, and 1.70 hr and 2.62 hr, respectively. Total bronchial and regional clearance was reproducible (P = .05) within subjects, but significant variation was observed among subjects. The predictions of the mathematical model for total bronchial clearance are in good agreement with the experimental results. However, the experimental clearance rate was slower in Zone I, and faster in Zone II and III than is predicted by the model. The implications of these results are discussed.

Adult↗