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In young, healthy people the alveolar-arterial P O 2 difference (A-aDO 2 ) is small at rest, but frequently increases during exercise. Previously, investigators have focused on ventilation/perfusion mismatch and diffusion abnormalities to explain the impairment in gas exchange, as significant physiological intra-pulmonary shunt has not been found. The aim of this study was to use a non-gas exchange method to determine if anatomical intra-pulmonary (I-P) shunts develop during exercise, and, if so, whether there is a relationship between shunt and increased A-aDO 2 . Healthy male participants performed graded upright cycling to 90%V O 2 max while pulmonary arterial (PAP) and pulmonary artery wedge pressures were measured. Blood samples were obtained from the radial artery, cardiac output (Q) was calculated by the direct Fick method and I-P shunt was determined by administering agitated saline during continuous 2-D echocardiography. A-aDO 2 progressively increased with exercise and was related toQ (r = 0.86) and PAP (r = 0.75). No evidence of I-P shunt was found at rest in the upright position; however, 7 of 8 subjects developed I-P shunts during exercise. In these subjects, point bi-serial correlations indicated that I-P shunts were related to the increased A-aDO 2 (r = 0.68),Q (r = 0.76) and PAP (r = 0.73). During exercise, intra-pulmonary shunt always occurred when A-aDO 2 exceeded 12 mmHg andQ was greater than 24 l min −1 . These results indicate that anatomical I-P shunts develop during exercise and we suggest that shunt recruitment may contribute to the widened A-aDO 2 during exercise.

Our research addresses how individual member behavior and institutional variables affect legislative success in the U.S. House of Representatives. Using new measures of activity from the 103d Congress (1993–94), a count dependent variable, and negative binomial regression, our analysis assesses member effectiveness. We find that a member's activity level encourages legislative success, but gains are limited when members speak or sponsor too frequently. Our results provide a clearer picture of the role of legislative context and the relevance of institutions in determining a member's legislative successes and failures.

Background-Recent reports suggest that off-label use of drug-eluting stents is associated with an increased incidence of adverse events. Whether the use of bare-metal stents would yield different results is unknown. Methods-We analyzed data from 6551 patients in the National Heart, Lung, and Blood Institute Dynamic Registry according to whether they were treated with drug-eluting stents or bare-metal stents and whether use was standard or off-label. Patients were followed for 1 year for the occurrence of cardiovascular events and death. Off-label use was defined as use in restenotic lesions, lesions in a bypass graft, left main coronary artery disease, or ostial, bifurcated, or totally occluded lesions, as well as use in patients with a reference-vessel diameter of less than 2.5 mm or greater than 3.75 mm or a lesion length of more than 30 mm. Results-Off-label use occurred in 54.7% of all patients with bare-metal stents and 48.7% of patients with drug-eluting stents. As compared with patients with bare-metal stents, patients with drug-eluting stents had a higher prevalence of diabetes, hypertension, renal disease, previous percutaneous coronary intervention and coronary-artery bypass grafting, and multivessel coronary artery disease. One year after intervention, however, there were no significant differences in the adjusted risk of death or myocardial infarction in patients with drug-eluting stents as compared with those with bare-metal stents, whereas the risk of repeat revascularization was significantly lower among patients with drug-eluting stents. Conclusions-Among patients with off-label indications, the use of drug-eluting stents was not associated with an increased risk of death or myocardial infarction but was associated with a lower rate of repeat revascularization at 1 year, as compared with bare-metal stents. These findings support the use of drug-eluting stents for off-label indications. IN 2003, THE FOOD AND DRUG ADMINISTRAtion (FDA) approved drug-eluting stents for the treatment of coronary artery disease. This decision was based on the results of clinical trials that compared a baremetal stent with a drug-eluting stent in highly selected patients. 1-10 Because of the magnitude of the treatment effect of drug-eluting stents in suppressing the recurrence of lesions, consistent