SUMMARY Using recently developed methods for measuring free-radical oxidation products in biological material, plasma extracts were studied in 24 women in the first two trimesters of pregnancy, in 124 women in the third trimester of pregnancy, in 20 women with pre-eclamptic toxaemia (PET), and in a control group. There was a significant progressive rise of two groups of free-radical oxidation products throughout pregnancy and a significantly greater rise in PET. In women whose diastolic blood pressure rose to above 70 mmHg there was a highly significant relation between two groups of free-radical reaction products and blood pressure.Methods weeks in 97 cases and at 40 weeks in 33 cases. A further study was carried out on eight women who were admitted with PET, the diagnosis being based on a rise in diastolic blood pressure (BP) to 90 mmHg or over with proteinuria or oedema or both. A control series of 14 non-pregnant women (aged 26·4 ± 7 years) included at least six on various oral contraceptive agents. The results in this group did not differ significantly from those in women during the first trimester of pregnancy, all falling within a very narrow range. Although a correlation between BP and some FR reaction products was not anticipated, the BP was measured and recorded at the time the blood samples were collected.Free-radical reaction products were measured by methods based on those described by Lunec and Dormandy," A scanning fluorescence spectroscope (MPF-3L, Perkin-Elmer, Beaconsfield, Bucks, UK) was used for all fluorescence measurements: 8 ml chloroform/methanol (2:1 v/v) was added to 1 ml plasma. The mixture was shaken for 2 minutes followed by centrifugation for 10 minutes at 1000 g. A preliminary study was carried out on blood from Of the resultant lower phase 5 ml was removed, and 36 women, 12 each in the first, second, and third 2 m1 deionised water was added. After vortex trimesters of pregnancy. The last eight weeks of mixing for 1 minute the mixture was spun for pregnancy were then studied in greater detail. Blood 10 minutes at 1000g. The lower phase formed will be was collected from 112 consecutive primigravid referred to as the 'chloroform' phase, and the upper women (aged 24· 6 ± 4· 6 years) attending the as the 'aqueous-methanol' phase. Two measurements antenatal clinic at the Whittington Hospital. Repeat were performed on the chloroform phase: 'diene samples from the same women were collected at 36 conjugation' measured by absorption at 240 nm; and 158

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No Cu(II) ion is measurable in human serum or synovial fluid by the phenanthroline assay. On storage of human serum or synovial fluid at 4 degrees C, phenanthroline-detectable copper appears, lipid peroxidation occurs, ferroxidase I activity declines and ferroxidase II activity rises, yet there is no fall in immunologically detectable caeruloplasmin. Storage of body fluids at -20 degrees C or -70 degrees C slows, but does not prevent, these deteriorative changes. It is suggested that the presence of low-molecular-mass Cu(II) ion complexes, ferroxidase II activity, "cytotoxic factors' and "immunosuppressive factors' in body fluids may be, in part or in whole, an artifact of the storage and handling of the fluids. A report [Blake, Blann, Bacon, Farr, Gutteridge & Halliwell (1983) Clin. Sci. 64, 551-553] that the caeruloplasmin present in rheumatoid synovial fluid is deficient in ferroxidase activity is shown to be such an artifact. It is strongly recommended that all such experiments be performed upon freshly taken fluid samples.

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Abnormalities of both free radical activity and ascorbic acid metabolism have been documented in diabetes, but their biological basis is unclear and their relationship unstudied in any detail. This study was designed to compare changes in antioxidant status and free radical reactions in a group of elderly diabetic patients (with and without retinopathy) with those in a group of age-matched control subjects. No significant differences in thiobarbituric acid (TBA) reactivity, red cell glutathione (GSH) concentrations or diene conjugates (DC) between patients and controls were seen despite significant depletion of ascorbic acid in patients with diabetes, especially in those with retinopathy. The results emphasise the present-day difficulties of measuring free radical activity and demonstrate a marked abnormality in ascorbic acid metabolism in diabetes.