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Previous studies of lung function in relation to smoking cessation have not adequately quantified the long-term benefit of smoking cessation, nor established the predictive value of characteristics such as airway hyperresponsiveness. In a prospective randomized clinical trial at 10 North American medical centers, we studied 3, 926 smokers with mild-to-moderate airway obstruction (3,818 with analyzable results; mean age at entry, 48.5 yr; 36% women) randomized to one of two smoking cessation groups or to a nonintervention group. We measured lung function annually for 5 yr. Participants who stopped smoking experienced an improvement in FEV(1) in the year after quitting (an average of 47 ml or 2%). The subsequent rate of decline in FEV(1) among sustained quitters was half the rate among continuing smokers, 31 +/- 48 versus 62 +/- 55 ml (mean +/- SD), comparable to that of never-smokers. Predictors of change in lung function included responsiveness to beta-agonist, baseline FEV(1), methacholine reactivity, age, sex, race, and baseline smoking rate. Respiratory symptoms were not predictive of changes in lung function. Smokers with airflow obstruction benefit from quitting despite previous heavy smoking, advanced age, poor baseline lung function, or airway hyperresponsiveness.

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.

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.

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.

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).