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Biomedical subjects

A F Wilson

Publications and source records attributed to A F Wilson.

At least 127 records · Page 7Linked to original sources
PubMed1984

Physiologic correlates of airway collapse in chronic airflow obstruction.

Forty percent of 89 patients with chronic airflow obstruction (CAO) demonstrated maximum expiration flow-volume (MEFV) patterns consistent with sudden collapse or marked narrowing of large central airways. In contrast, 43 percent of the CAO patients demonstrated a curvilinear (C) pattern; the remainder (17 percent) were intermediate. Volume displacement plethysmography indicated that the airway collapse (AC) pattern was influenced by, but was not solely, a gas compression artifact. Airway collapse patients had more obstruction and hyperinflation than C patients and also had decreased diffusing capacity, absence of density dependence, reduced lung recoil, and no effort dependence of airflow. Bronchodilator administration in AC patients typically produced large reduction of residual volume and increase of vital capacity, with a smaller increase of airflow. These data suggest that AC patients have significant, partially reversible peripheral airways obstruction plus emphysema. Possible determinants of AC include reduced central airway support, increased peripheral resistance, loss of lung recoil, and increased pleural pressures during forced expiration. The MEFV contour appears to evolve from normal to curvilinear to the AC pattern as the severity of airflow obstruction worsens.

Aged↗
PubMed1983

Metabolic control in a state of decreased activation: modulation of red cell metabolism.

Very little is known in depth of the biochemical and physiological changes induced at the cellular level by human behavioral states. For study of the physiology of behavior at this level, the erythrocyte may be useful, because it is readily available and its metabolism and metabolic control are comparatively well understood. In this report we describe a marked decline of red cell glycolytic rate induced by the transcendental meditation technique (TM). This decline was significantly correlated with decreased plasma lactate concentration and with relaxation as indicated by electrodermal response. The occurrence of sleep was not correlated with the metabolic changes. The observed lack of variation of blood pH, blood gases, glucose, and hematocrit in this behavior implies that the decrease of erythrocyte metabolism is not an epiphenomenon of respiratory change or substrate availability. Based upon further measurements indicating persisting alteration of the red blood cell, we suggest the possibility of attachment of a humoral agent(s) to the cell in the mechanism of this effect. This behavioral effect is unique, and the effector(s) responsible may increase our understanding of metabolic control of the erythrocyte and of TM.

Aerobiosis↗
PubMed1983

Forearm blood flow and metabolism during stylized and unstylized states of decreased activation.

We have measured forearm oxygen consumption and blood flow changes during two wakeful rest behaviors. We have observed acute reduction of forearm respiration (28%) during an acute stylized rest state (TM) and a nonsignificant small decline (11%) during unstylized ordinary eyes-closed rest. These changes were not associated with significant change of forearm blood flow or glycolytic metabolism. Hence, forearm oxygen consumption decline was due almost solely to decreased rate of oxygen extraction. Small variation of forearm blood flow implies that little of the previous findings of increased nonrenal, nonhepatic circulation during TM or increased nonrenal circulation during ordinary rest can be accounted for by altered muscle blood flow, which therefore is consistent with possible increased cerebral blood flow. However, reduced muscle metabolism was a likely contributor to the forearm metabolic decline. The lack of coupling between metabolic and blood flow changes during TM indicates limitation of obligatory coupling between cardiovascular and metabolic function in the rest state of TM.

Adult↗
PubMed1983

Flow-volume curves reflect pharyngeal airway abnormalities in sleep apnea syndrome.

Twenty-nine patients with disorders of excessive somnolence were evaluated with standard nocturnal polysomnography, fiberoptic laryngoscopy, and flow-volume curves. Twenty-two had evidence of obstructive sleep apnea (OSA) by polysomnography and most had abnormal flow-volume curves, supporting earlier observations. Three of 7 patients without obstructive sleep apnea also had abnormal curves. Fiberoptic nasopharyngoscopy was performed in the OSA group while awake to evaluate the upper airway. Sixteen patients of the OSA group demonstrated pharyngeal obstruction; 14 of those with visualized airway obstruction had flow-volume abnormalities. In the 6 patients of the OSA group with no significant visual obstruction, 5 had normal curves. The flow-volume curve appears to correlate with direct visual assessment of upper airway patency during wakefulness in those patients demonstrating obstruction during sleep.

Adult↗
PubMed1983

A comparison of incremental exercise tests during cycle and treadmill ergometry.

We evaluated a short-duration maximum exercise test by comparing a 15-s incremental exercise protocol with a 1-min incremental method. Twenty normal men and women were studied using cycle and/or treadmill ergometry. In subjects tested on both exercise devices, anaerobic threshold and maximal oxygen uptake (VO2max) were higher for both protocols on the treadmill than on the cycle ergometer (P less than 0.001). However, when the 15-s and 1-min tests were compared using the same device (treadmill or cycle), there were no significant differences between protocols in anaerobic threshold or maximum exercise values of minute ventilation, respiratory rate, tidal volume, VO2max, oxygen pulse, and peak expiratory flow rate. Linear regression analyses indicated differences between the 15-s and 1-min protocols when cardiopulmonary measurements were related to power; however, the two protocols were comparable when cardiopulmonary data were related to oxygen uptake. Comparisons between protocols or between exercise devices were not systematically different in large vs small individuals, or in men vs women. Short-duration incremental exercise tests appear to be reliable, practical methods for assessing exercise performance in normal individuals.

Exercise Test↗
PubMed1983

Restrictive ventilatory dysfunction in stroke: its relation to locomotor function.

Static and dynamic lung volumes, maximum respiratory pressures and lung compliance and resistance were registered in 54 subjects with hemiplegia or hemiparesis after stroke. These measures of ventilatory function were related to the degree of motor impairment and to the interval between stroke and investigation. In general ventilatory function, particularly parameters depending upon expiratory force, was restricted. This was most pronounced in subjects with severe hemiplegia while those with hemiparesis had only small changes. Since dynamic lung volumes (corrected for volume loss), lung compliance and resistance were all normal, it is evident that intrinsic lung function was unaffected. Inspiratory capacity - but no other measured variables of respiratory function - was lower six months after the stroke than earlier. It is suggested that expiratory muscle dys-coordination and weakness caused expiratory dysfunction while the less pronounced inspiratory restriction may be caused by muscular dysfunction and, as time goes by, by rib cage contracture.

Adult↗
PubMed1982

Theoretical basis of single breath gas absorption tests.

Absorption of gas from alveoli is examined in a simplified model of the respiratory system during a stylized single breath consisting of constant inspiratory flow, constant expiratory flow, and breathholding. The equations describing gas behavior are general since they are based upon conservation of mass. The equations simplify considerably when gases that are not soluble in pulmonary tissue and/or blood are utilized. In a three-compartment model, diffusing capacity of the lung for carbon monoxide (DCO) will be underestimated except when both uneven distribution of lung volume and DCO are present; under most circumstances, the standard clinical 10-s method [9] is at least as accurate as any other. When pulmonary capillary blood flow (Qc) is calculated by the one point method [2] in a one-compartment lung, it is underestimated; in the three-compartment model, it is underestimated except when both uneven distribution of Qc and lung volume are present. The multiple single breath method [2] accurately measures DCO and Qc. Measurement of pulmonary tissue volume is improved by correcting the value of the intercept of acetylene absorption to the time when carbon monoxide apparently began rather than utilizing the beginning of inspiration.

Capillaries↗
PubMed1982

Muscle and skin blood flow and metabolism during states of decreased activation.

Acute decline of forearm oxygen consumption has been observed during an acute, wakeful behaviorally induced rest/relaxed state. This change of tissue respiration was not associated with variation of rate of forelimb lactate generation. Since forearm blood flow did not change significantly during this behavior, the decline of oxygen consumption by forearm was due almost solely to decreased rate of oxygen extraction. Decreased muscle metabolism was a likely contributor to these observations. The occurrence of sleep was not related to the metabolic change. The lack of coupling between the metabolic and blood flow changes during this state of decreased activation suggests limitation of the hypothesis of obligatory coupling between systemic and/or regional cardiovascular and metabolic function.

Adult↗
PubMed1982

Ultrastructural evidence of pulmonary capillary endothelial damage from paraquat.

Because of lack of agreement concerning the toxicity of paraquat to the pulmonary microvasculature, we have undertaken an electron microscopic study of lungs of paraquat-treated rats. Rats were injected with paraquat or sterile water (controls) intraperitoneally; the animals were then killed at 24-h intervals for 10 days post-injection. In the control animals, lung ultrastructure remained normal throughout the study. In treated animals, the initial evidence of alveolar epithelial injury occurred 24 h post-paraquat. By 48 h, severe fragmentation and desquamation of membranous pneumocytes occurred, and both alveolar and interstitial edema were present. Epithelial damage was maximal 72-96 h post-paraquat. Pulmonary capillary endothelial abnormalities were less extensive than the alveolar epithelial lesions. Endothelial damage was first observed 48 h post-paraquat. In endothelial cells on the septal (thick) side of the capillaries, the number of pinocytotic vesicles was significantly increased (P less than 0.05) from 48 to 96 h post-paraquat. In endothelium adjacent to damaged epithelium, abnormalities included hydration, fragmentation, discontinuity, and widened intercellular junctions; these were maximal 72-96 h post-paraquat. Although other mechanisms are probably important, damaged pulmonary capillary endothelium seems to be a factor favoring paraquat-induced pulmonary edema.

Animals↗
PubMed1981

Inhaled atropine sulfate in acute asthma.

We administered inhaled atropine sulfate to acute asthmatics already receiving therapeutic doses of adrenergic agonists, theophylline, and corticosteroids. Following atropine, hyperinflation diminished whereas vital capacity and expiratory flow rates breathing air and helium-oxygen increased (p less than 0.025 - p less than 0.005). Initial density dependence correlated inversely with changes in density dependence after atropine (r = -0.69, p less than 0.001). We conclude that: (1) inhaled atropine sulfate was effective therapy for acutely ill asthmatics already being treated with multiple antiasthmatic agents; (2) atropine caused large and peripheral airways bronchodilatation, and (3) the predominant site of bronchodilatation after atropine was related to the site of flow limitation before atropine.

Acute Disease↗
PubMed1981

Relationship between sites of airflow limitation and severity of chronic airflow obstruction.

We studied the relationship between sites of airflow limitation and severity of chronic obstructive pulmonary disease. Pre- and postbronchodilator physiologic testing was performed in 30 subjects with chronic airflow obstruction (CAO). Pulmonary function, including the increase in maximal expiratory flow at 50% of vital capacity after helium-oxygen breathing (delta VEmax50), was reduced before and after inhalation of 1.3 mu mg of metaproterenol. Significant correlations were present between values for delta VEmax50 and measurements of expiratory flow (p < 0.001). In subjects with severe CAO (one-second forced expiratory volume less than or equal to 1.2 L; percentage ratio of one-second forced expiratory volume to forced vital capacity < 50%), delta VEmax50 was always abnormally decreased. An inverse relationship was present between initial delta VEmax50 and changes in delta VEmax50 after inhalation of metaproterenol (p < 0.001). These results suggest that the site of airflow limitation becomes progressively more peripheral as CAO worsens, and that severe CAO is usually associated with peripheral sites of airflow limitation.

Aged↗
PubMed1981

Site and duration of bronchodilation in asthmatic patients after oral administration of terbutaline.

We compared pulmonary function in 15 asthmatic subjects before and after ingestion of 5 mg terbutaline and placebo. Measurements of maximal expiratory flow (VEmax), density-dependence of VEmax (delta VEmax50), volume of isoflow (Viso V), residual volume (RV), and closing capacity (CC) were performed before and 15, 135, 255, and 375 minutes after both treatments. After placebo VEmax improved mildly (P < 0.05) but no significant changes occurred in delta VEmax50, VisoV, RV, or CC. After terbutaline, VEmax increased significantly and VisoV, RV, and CC decreased significantly at all time periods studied. In addition delta VEmax50 increased compared to baseline at 15 and 135 minutes (P < 0.05) and compared to placebo at 135 and 255 minutes (P < 0.05). In our study, orally administered terbutaline apparently caused predominant peripheral airways bronchodilatation in the first few hours after ingestion. Afterwards, the predominant small airways effect appeared to wane, and large and small airways were dilated proportionately equally 375 minutes after oral administration of terbutaline.

Adult↗
PubMed1981

Effects of breathing retraining in patients with chronic obstructive pulmonary disease.

Subjects with severe chronic obstructive pulmonary disease (COPD) were studied to evaluate the effects of breathing retraining (BRT) on exercise tolerance. Twenty-two subjects exercised on a treadmill three times weekly for six weeks. Twelve of the subjects (controls) then exercised for three more weeks; the other ten subjects received three more weeks of exercise reconditioning plus BRT. Results of routine pulmonary function and exercise tests were similar in both groups at the beginning of the study and after six weeks of exercise. However, in the last three weeks of the study, increments in exercise performance were significantly greater in the BRT subjects than in controls (P less than .002). Following BRT, respiratory rate during exercise decreased (P less than .005) and tidal volume and PaO2 during exercise increased (P less than .05). Thus, these data suggest that BRT increases exercise performance in subjects with severe COPD.

Breathing Exercises↗
PubMed1980

Pulmonary disease in workers exposed to papain: clinico-physiological and immunological studies.

Of the twenty-three employees at a pharmaceutical plant manufacturing a new product containing papain, twelve had respiratory symptoms of cough, wheezing, dyspnoea, or chest paint. Most were studied with in-depth interviews by a doctor, extensive pulmonary function tests, and immunoserological tests for IgE and precipitating antibodies specific for papain, as well as total IgE antibodies to common natural allergens. There were significant correlates (all P values < 0.05) between the presence of specific IgE antibodies to papain and decreases of FEV1, FEF75--85, TLC, RV, and response to bronchodilators as percentage change from baseline for all spirographic flow rates. Atopic workers developed pulmonary symptoms and antipapain antibodies significantly sooner after papain exposure than did the others. Duration of exposure had no effect on symptomatology, pulmonary function, or immunological response. However, those judged to have the greatest amount of dust exposure per work-day had significantly more pulmonary symptoms (P < 0.005). Papain produced lung diseases by acting as an inhalant allergen rather than a proteolytic enzyme. Papain is a potent sensitizer in humans for the production of respiratory disease. The pulmonary reactions, based on physiological data, seem to involve small airways, alveolar, and interstitial lung tissue in an inflammatory rather than destructive manner, and thus resemble bronchitis and interstitial lung disease rather than pulmonary emphysema or typical bronchial asthma.

Adult↗
PubMed1980

Relationship between the site of airflow limitation and localization of the bronchodilator response in asthma.

In an effort to determine the relationship between the major sites of airflow limitation and bronchodilator action, physiologic studies were performed in 65 asthmatics before and after the administration of isoproterenol, metaproterenol, or terbutaline. Before the administration of a bronchodilator, the results of routine pulmonary function tests were abnormal; the mean increment in maximal expiratory flow at 50% of forced vital capacity (delta VEmax50) after breathing 80% helium-20% oxygen (He-O2) was reduced (p < 0.001). Prebronchodilator values of delta VEmax50 correlated linearly with VEmax50 breathing air (r = + 0.68, p < 0.001). These data suggested that airflow limitation becomes more peripheral as asthma becomes more severe. After the bronchodilator administration, the results of routine pulmonary function studies improved; delta VEmax50 either increased or decreased, depending upon the prebronchodilator values. Density-dependence tended to (1) increase in subjects with low prebronchodilator values of delta VEmax50, and (2) decrease in subjects with high prebronchodilator values of delta VEmax50. Hence, these results suggested that predominant sites of bronchodilatation in asthmatics are related to the prebronchodilator sites of airflow limitation.

Adult↗
PubMed1980

Response to inhaled metaproterenol and isoproterenol in asthmatic and normal subjects.

Pulmonary function tests were performed before and after inhalation of 1.3 mg of metaproterenol sulfate or 150 microgram of isoproterenol hydrochloride by 40 asthmatic and 40 normal subjects. PHysiologic measurements included spirometric testing, plethysmographic studies, and maximal expiratory flow-volume curves obtained after inhalation of air and a mixture of 80 percent helium and 20 percent oxygen. In the normal subjects, pulmonary function improved significantly after inhalation of both metaproterenol and isoproterenol. There was no significant difference in responsiveness to either bronchodilator drug. In the asthmatic subjects, pulmonary function also improved significantly after both bronchodilator agents. The sites of predominant bronchodilatation were similar in the asthmatic subjects after both metaproterenol and isoproterenol; however, bronchodilatation was better overall (P less than 0.005) and for most individual tests with metaproterenol. The greater efficacy of metaproterenol in asthmatic subjects but not in normal subjects can be explained by (1) different doses of the bronchodilator drug and (2) differing bronchodilator dose-response relationships in asthmatic and normal subjects.

Adult↗