The aim of this study was to determine whether a relationship exists between the circulating concentration of antioxidants, or markers of oxidative stress, and pulmonary function in cystic fibrosis patients. Plasma was obtained from 34 patients attending a cystic fibrosis clinic. Oxidative stress was investigated by measuring the concentrations of circulating lipid hydroperoxides and malondialdehyde (lipid peroxidation) and protein carbonyls (protein oxidation). Antioxidant status was determined from the plasma concentrations of α-tocopherol, ascorbic acid, uric acid and total sulphydryls. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and forced mid-expiratory flow (FEF25-75) were measured in 25 of the subjects by spirometry, and expressed as percentage predicted for normal height, weight and age.Lung function decreased significantly with age and was associated with decreased plasma α-tocopherol, ascorbic acid and sulphydryl concentrations. The reduction in pulmonary function correlated with elevated plasma malondialdehyde, but not with lipid hydroperoxide or protein carbonyl concentrations. Patients with severe lung dysfunction (FEV1 <50% predicted) had higher plasma concentrations of lipid hydroperoxides than those with mild-to-moderate lung dysfunction (FEV1 >50% pred).This study provides evidence that cystic fibrosis patients have inadequate antioxidant defences to cope with the elevated oxidative stress that they regularly experience. We believe that recurring oxidative lung injury contributes to the decline in pulmonary function in these patients.

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The magnetic field dependence of the superconducting transition has been studied in triangular arrays of Pb-Sn proximity-coupled junctions. The transition temperature T, and the array resistance R (T) are found to vary periodically in a perpendicular magnetic field with a period corresponding to one flux quantum per unit ce11 of the array. In addition, both quantities show substructure at rational fractions of a flux quantum

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