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Biomedical subjects

P D Scanlon

Publications and source records attributed to P D Scanlon.

At least 19 recordsLinked to original sources
PubMed1995

Cessation of long-term nicotine gum use--a prospective, randomized trial.

Nicotine gum is an important adjunct for smoking cessation for many smokers, and long-term use of nicotine gum will occur in a small percentage of patients. To date, no method of cessation in long-term users has been studied in a randomized trial. We enrolled 26 subjects at the Mayo Clinic site of the Lung Health Study who had used nicotine gum for more than 6 months to participate in a trial where subjects were randomly assigned to: (1) abrupt cessation, (2) taper with placebo gum, or (3) taper with active gum. At the end of the 6-week trial, the percentage of subjects abstinent from gum use and not smoking was not different among the three groups: 66.7% for the abrupt cessation group, 71.4% for the taper with placebo gum group and 60% for the taper with active gum group. One subject in the taper with placebo gum group relapsed to smoking during the trial but was abstinent from smoking again at long-term follow-up. Long-term follow-up (median 284 days) showed 65% of subjects were abstinent from all nicotine products. Motivated subjects can stop long-term nicotine gum use without relapse to gum use or smoking by either abrupt cessation or brief tapering.

Adult↗
PubMed1995

Fatty acid kinetic responses to running above or below lactate threshold.

During running exercise above the lactate threshold (LT), it is unknown whether free fatty acid (FFA) mobilization can meet the energy demands for fatty acid oxidation. This study was performed to determine whether FFA availability is reduced during running exercise above compared with below the LT and to assess whether the level of endurance training influences FFA mobilization. Twelve marathon runners and 12 moderately trained runners ran at a workload that was either above or below their individual LT. Fatty acid oxidation (indirect calorimetry) and FFA release ([1-14C]palmitate) were measured at baseline, throughout exercise, and at recovery. The plasma FFA rate of appearance increased during exercise in both groups; running above or below the LT, but the total FFA availability for 30 min of exercise was greater (P < 0.01) in the below LT group (marathon, 23 +/- 2 mmol; moderate, 21 +/- 2 mmol) than in the above LT group (18 +/- 3 and 13 +/- 3 mmol, respectively). Total fatty acid oxidation (indirect calorimetry) greatly exceeded circulating FFA availability, regardless of training or exercise group (P < 0.01). No statistically significant exercise intensity or training differences in fatty acid oxidation were found (above LT: marathon, 71 +/- 12, moderate, 64 +/- 17 mmol/30 min; below LT: marathon 91 +/- 12, moderate, 60 +/- 5 mmol/30 min). In conclusion, during exercise above or below LT, circulating FFA cannot meet the oxidative needs and intramuscular triglyceride stores must be utilized. Further marathon training does not enhance effective adipose tissue lipolysis during exercise compared with moderate endurance training.

Adipose Tissue↗
PubMed1995

Role of chest physicians in detection and treatment of occupational and environmental respiratory disease. A practice survey.

A survey of American College of Chest Physicians (ACCP) members was conducted to determine their degree of involvement in the diagnosis and prevention of occupational and environmental respiratory disease (OERD). Although the response rate was relatively low, the results are likely to be representative. Calculations based on the data estimate that in the prior year, chest physicians on the average saw 15 patients with OERD caused by work, 13 worsened by work, and 28 affected by the home environment. Asthma appears to be a more common occupational or environmental concern than pulmonary fibrosis. Chest physicians clearly perceived a need for more education in OERD. The survey also demonstrated that although many chest physicians perform routine industrial surveillance testing, it is often done without using standardized methods. Furthermore, chest physicians are actively involved with medical/legal aspects of OERD. Overall, the survey documents the role of chest physicians in the area of OERD and emphasizes significant educational needs.

Adult↗
PubMed1994

Bronchoconstriction occurring during exercise in asthmatic subjects.

To demonstrate physiologic changes associated with asthma symptoms that many patients with asthma develop during exercise, we used sustained constant-load and interval exercise protocols with subjects breathing dry room temperature air. In constant-load exercise, subjects pedaled a stationary bicycle at 50% of their maximal power capacity for 36 min. In interval protocols, subjects pedaled at 60% of maximal capacity for 6 min and then 40% of maximal for 6 min; the 12-min cycle was repeated three times for a total exercise time of 36 min. Maximal expiratory flow versus volume maneuvers (MEFV) were obtained before, at 6-min intervals during, and at 5-min intervals after exercise. Changes in peak expiratory flow (PEF), forced expiratory volume in 1 s (FEV1), and forced expiratory flow at 50% of pre-exercise vital capacity (FEF50) were compared with pre-exercise values. Within 15 min after a maximal 1-min incremental exercise protocol, mean flows decreased compared with pre-exercise (PEF, mean -22%, range -46 to 5%; FEV1, mean -21%, range -42 to -3%; FEF50, mean -41%, range -80 to 3%; all p < 0.05). There were no significant changes in MEFV flows until 18 min of constant-load exercise, when FEV1 and FEF50 fell (FEV1, mean -6%, range -15 to 2%; FEF50, mean -14%, range -32 to 6%; both p < 0.05), although changes in PEF were minimal and were not significantly different compared with pre-exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Comparison of four methods for calculating diffusing capacity by the single breath method.

In 283 patients referred for testing in an outpatient pulmonary function laboratory, we studied the single-breath diffusing capacity of the lungs for carbon monoxide (Dco) using the Ogilvie (Og), Jones-Meade (JM), Epidemiological Standardization Project (ESP), and three-phase iterative methods (3PIT, similar to the three equation method). The Dco maneuvers were performed using automated equipment and American Thoracic Society (ATS) recommended procedures. There were small but significant differences in mean Dco, the ESP method yielding the largest, followed in order by JM, 3PIT, and Og methods. The 3PIT and JM Dcos were in close agreement in all degrees and patterns of pulmonary function abnormality. The Og Dco method was 6 percent less than JM in patients with normal pulmonary function, although the difference was less in patients with expiratory flow limitation, restriction, or reduced Dco. There were no differences in the reproducibility of Dco measurements among the methods. Based on these results and a review of the literature, we conclude the following: (1) when measuring single-breath Dco using automated equipment that follows ATS recommended procedures for collecting a single expired gas sample of 500-ml volume, calculated Dco is largest using ESP method, following by JM, 3PIT, and Og methods; (2) in patients with reduced Dco associated with obstructive or restrictive abnormalities, the Og, 3PIT, and JM timing methods are nearly equivalent; and (3) reproducibility of Dco is the same by all methods.

Airway Obstruction↗
PubMed1993

Preoperative pulmonary function testing for patients with lung cancer.

Preoperative functional assessment of patients who are scheduled to undergo pulmonary resection for carcinoma of the lung can assist the clinician in determining perioperative risk. Physiologic alterations that occur after thoracotomy, including changes in lung volume, ventilatory pattern, gas exchange, and respiratory defense mechanisms, impose an increased risk of complications in patients with moderate to severe respiratory impairment. The use and shortcomings of preoperative spirometry and arterial blood gas analysis as predictors of perioperative complications are reviewed. Quantitative radionuclide scintigraphy, and in some cases exercise testing, can further determine the operative risk of patients with lung cancer. For patients with increased risk, implementation of prophylactic measures may decrease postoperative complications.

Blood Gas Analysis↗
PubMed1992

A study of aqueous humor formation in patients with cystic fibrosis.

The circadian pattern of aqueous formation and the effect of timolol on aqueous flow was studied in 12 patients with cystic fibrosis. Cystic fibrosis is a disease characterized by a defect in a chloride channel-associated regulatory protein found in epithelial cells. Improper regulation of these chloride channels, causes abnormal composition of exocrine secretions, including respiratory tract, gastrointestinal tract, exocrine pancreas, and sweat glands. Ocular findings previously reported include abnormal endothelial cell permeability, decreased tear secretion, and abnormal tear composition. In this study, aqueous humor flow was measured by fluorophotometry. No statistically significant difference was found when flow rates measured during the morning, during the afternoon, at night, and after topical timolol treatment were compared to normal values. The conclusion is that the beta adrenergically regulated chloride selective channels defective in patients in cystic fibrosis do not play a major role in the formation of aqueous humor or they are not regulated by the cystic fibrosis transmembrane conductance regulator (CFTR).

Administration, Topical↗
PubMed1990

Effect of inhaled methacholine on inspiratory flow.

One hundred consecutive outpatients with symptoms suggestive of asthma who came to the Pulmonary Function Laboratory for a methacholine challenge test were studied. In addition to the forced expiratory maneuvers, forced inspiratory maneuvers were performed before and after the maximal response to methacholine. In 24 patients, the methacholine challenge suggested that they had asthma (forced expiratory volume in 1 s [FEV1] decrease greater than or equal to 20 percent). Six of these 24 patients also had a decrease in maximal forced inspiratory flow (FIFmax) greater than or equal to 20 percent and nine had a decrease in forced inspiratory flow at 50 percent of vital capacity (FIF50) greater than or equal to 20 percent, suggesting that bronchoconstriction can cause decreased inspiratory as well as expiratory flows. In 76 patients, the methacholine challenges were "negative" (FEV1 decrease less than or equal to 20 percent), suggesting that they did not have asthma. Nevertheless, in 11 of these 76 patients the FIFmax decrease was greater than or equal to 20 percent, and in 14 patients the FIF50 decrease was greater than or equal to 20 percent, suggesting that intermittent central airway obstruction is responsible for these patients' symptoms.

Administration, Inhalation↗
PubMed1989

Respiratory mechanics in acute quadriplegia. Lung and chest wall compliance and dimensional changes during respiratory maneuvers.

We measured lung and chest wall compliance as well as rib cage and abdominal dimensions in the supine position in five acute C4-7 quadriplegics. Studies were performed serially from 1 to 12 months after injury. Results were compared with those of control groups of chronic (greater than 1 yr after injury) quadriplegics and normal volunteers. We found that lung compliance was lower in acute and chronic quadriplegics (0.129 +/- 0.023 and 0.176 +/- 0.043 L/mm Hg, respectively) than in normal subjects (0.278 +/- 0.086 L/mm Hg) and that these changes apparently occurred within 1 month of injury. Specific lung compliance appeared to be reduced to a lesser degree, suggesting that the changes in lung compliance were partly due to reduced lung volumes and partly to altered mechanical properties of the lung. During respiratory maneuvers, abdomen and rib cage dimensional changes demonstrated rib cage distortion. This distortion was less severe in chronic than in acute quadriplegics. The improvement in chest wall stability was likely due to increased strength of cervical accessory muscles of respiration and improved coupling of the various rib cage elements in chronic quadriplegics.

Acute Disease↗
PubMed1987

Bronchoconstrictor effects of leukotriene E4 in normal and asthmatic subjects.

The bronchoconstrictor activity of an aerosol of leukotriene E4(LTE4) was compared with that of histamine in 5 normal and in 6 asthmatic subjects to define the relative potency of LTE4 between the groups using 3 indices of airway response. The FEV1 and the flow rate measured at 30% of vital capacity from partial and maximal expiratory maneuvers (V30-P and V30-M) were measured. The geometric mean (GSEM) concentration of LTE4 required to reduce the V30-P by 30% was 0.30 (1.46) mM in the normal subjects, and 0.058 (1.63) in the asthmatic subjects; LTE4 was 39-fold more potent than histamine in the former and 14-fold in the latter group. Further, we observed that when normal and asthmatic subjects were compared at a degree of bronchoconstriction resulting in a 30% decrement in the V30-P after inhaling LTE4, there was a greater response in the asthmatic group than in the normal group of the accompanying change in the FEV1. The decrements in the FEV1 were not significantly different between the 2 groups after inhaling histamine. This study demonstrates that LTE4 is a potent bronchoconstrictor agonist in humans and suggests that airway responsiveness to this agonist differs substantially with the index of bronchoconstriction used for assessment of airway response.

Aerosols↗