To investigate whether endothelial dysfunction of pulmonary arteries (PA) is present in patients with mild chronic obstructive pulmonary disease (COPD) and to what extent it is related to the morphological abnormalities of PA, we studied 41 patients who underwent lung resection. Patients were divided into the following groups: nonsmokers ( n = 7), smokers with normal lung function ( n = 13), and COPD ( n = 21). Endothelium-dependent relaxation mediated by nitric oxide was evaluated in vitro in PA rings exposed to cumulative concentrations of acetylcholine (ACh) and ADP. Structural abnormalities of PA were assessed morphometrically. PA of COPD patients developed lower maximal relaxation in response to ADP than both nonsmokers and smokers ( P < 0.05 each) and a trend to reduced relaxation in response to ACh ( P = 0.08). Maximal relaxation to ADP correlated with the degree of airflow obstruction ( r = 0.48, P < 0.01). Morphometrical analysis of PA revealed thicker intimas, especially in small arteries, in both smokers and COPD compared with nonsmokers ( P < 0.05 each). We conclude that endothelial dysfunction of PA is already present in patients with mild COPD. In these patients, as well as in smokers with normal lung function, small arteries show thickened intimas, suggesting that tobacco consumption may play a critical role in the pathogenesis of pulmonary vascular abnormalities in COPD.

The intraclass correlation coefficient (ICC) and the concordance correlation coefficient (CCC) are two of the most popular measures of agreement for variables measured on a continuous scale. Here, we demonstrate that ICC and CCC are the same measure of agreement estimated in two ways: by the variance components procedure and by the moment method. We propose estimating the CCC using variance components of a mixed effects model, instead of the common method of moments. With the variance components approach, the CCC can easily be extended to more than two observers, and adjusted using confounding covariates, by incorporating them in the mixed model. A simulation study is carried out to compare the variance components approach with the moment method. The importance of adjusting by confounding covariates is illustrated with a case example.

No abstract

The ~nfluence of a trawling moratorium on the breedlng ecology of Audouin's gulls (Larus audouinii Payraudeau) was investigated during 1992 and 1993 in the largest colony of the species in the world (70% of total population), at the Ebro Delta, NE Spain. western Mediterranean. In this colony, Audouin's gull behaves partly as a scavenger following the trawling fleet and exploiting fishing discards. Each year, the trawling moratorium affected different breeding stages of the species: in 1992 it overlapped with pre-laying and laying stages, while in 1993 it affected most of the chick-rearing stage. We examined differences in laying dates, laying interval, clutch and egg slzes, nest desertion during laying, hatching success, hatchling mass and condition, growth rates, chick survival and breeding success. The moratorium greatly affected egg production in 1992, delaying the start of l a y~n g and dramatically decreasing clutch and egg sizes. Intraclutch egg size variation between the 2 years suggests that egg size profiles are outcomes of the interaction between physiological and environmental factors rather than the result of ultimate factors. Nest desertion was much higher in 1992, probably because some females were under a critical body condit~on threshold and they deserted after laying the first egg. Hatching success also decreased significantly during 1992, probably related to changes in the size and the quality of the eggs. Chick growth and survivorship was h~g h e r in 1992, when trawler discards were normally available, than in 1993. Trawler discard availability during chick rearing was more important than egg size in determining chick survival. However, differences were not always significant, since In 1993 the n~oratorium did not start until the chicks were 1 wk old, and, further, chicks had h~g h e r skeletal size and body condition (in order of Importance) than In 1992. In fact, chicks had similar fledgling condition in both years at the end of the reanng stage. In 1993, the overall breeding success decreased by 4 8 % Nevertheless, gulls' breed~ng performance for the 2 years was much lower than before the establishment of the flrst moratorium In 1991, and the situation suggests that clupeo~ds, the prey on wh.ich Audouin's gull feed, are scarce. It seems that gulls were not able to compensate for the lack of trawler discards during egg production, since the avallablllty of secondary feeding resources was much lower in March and April (pre-laying and laying stages) than in June (chick-rearing stage). Although in long-lived species a decrease in food supply should affect fecundity before affecting adult survival, results confirm the importance of the trawler fleet activity for the conservat~on of this threatened species.