I. The long-term fate of an oral dose of [75Se]selenomethionine was studied in four women. 2 . Urinary and faecal excretion, respiratory losses and whole-body retention of 75Se were measured, and also 75Se turnover in whole body, plasma and erythrocytes during a period of 33-44 weeks.3. Intestinal absorption of [75Se]selenomethionhe by the four subjects was 95'5-97'3 % of the administered dose.4. Urinary excretion accounted for 6-9% of absorbed 75Se in the first z weeks. No radioactivity was detected in expired air.5 . After the initial 8 weeks during which radioactivity decreased more rapidly, wholebody retention of 75Se decreased exponentially with a half-time of 207-290 d.6 . Plasma 75Se concentration reached a maximum level 3-4 h after the dose. Transient initial uptake of 75Se in erythrocytes during the first hour was followed by a gradual increase to a maximum concentration at 8-12 weeks.7. These results are compared with the results of an earlier study of the metabolism of [75Se]selenite in two of the same women. '%e from [76Se]selenomethionine was found to be more completely absorbed, had a greater retention and smaller endogenous urinary and faecal losses than W e from [75Se]selenite, and these differences persisted throughout the experimental period. These findings differed from those obtained in rats in which, after an initial period, 75Se from selenite was metabolized similarly to that from selenomethionine.The unusually low concentration of selenium in the blood of New Zealand residents has stimulated interest in its possible role in human nutrition (Griffiths, 1973; Griffiths & Thomson, 1974; Watkinson, 1974;Robinson, 1975). Although it is not established that the intake of Se should be increased, information is required about the metabolism of Se in man. The fate of an oral dose of [75Se]selenite was studied in three women (Thomson & Stewart, 1974) and in the present study the fate of an oral dose of [75Se]selenomethionine has been studied in four women, of whom two were subjects in the previous experiment. E X P E R I M E N T A L ProcedureThe subjects G, R, C and T were four women aged 34, 26, 22 and 23 years respectively, with a mean height of 1-63 m and a mean weight of 60 kg. Subjects G and R had also participated in the previous study (Thomson & Stewart, 1974

I . Quantitative selenium metabolism has been studied in normal young New Zealand women by measuring total Se intake and urinary and faecal Se output, and by using values for absorption, excretion and turnover of 75Se determined after administration of [75Se]selenomethionine or [75Se]selenite. 4. Whole-body Se was calculated in three different ways; (a) using the specific activity of urinary Se and retained whole-body 75Se; (b) using plasma Se and the occupancy of 75Se in whole-body and plasma; (c) using absorbed food Se and the occupancy of absorbed 'Se in whole-body.5. Whole-body Se calculated from measurements obtained following the administration of [75"S]selenomethionine was 4.7-10.0 mg (mean 6.9) using method (a), 4'1-7'2 mg (mean 5.2) using method (b) and 4.3-8.9 mg (mean 6.2) using method (c).6. Whole-body Se calculated from results obtained after giving [75Se]selenite was 2.7-3.4 mg (mean 2.9) using method (a), 2.3-5.0 mg (mean 3.5) using method (b) and 2.1-3.0 mg (mean 2.6) using method (c).7. The results of this study indicate that the minimum dietary requirement of Se for the maintenance of normal human health is probably not more than 20 pg/d.

Virtual poster abstracts Results: Population: 526. There was no significant association between Doppler or cCTG and adverse outcome at birth (n = 29). An association between antenatal predictors and neonatal morbidity was found at discharge (table 1). Binary logistic regression showed that gestational age (GA) at birth was the main predictor of composite neonatal morbidity at discharge (adjusted OR 0.61, p = 0.003). Conclusions: GA at delivery, rather than Dopplers or cCTG, appears to be the main determinant of neonatal morbidity at discharge in this population of SGA babies.

Objectives: Maternal hemodynamics in pregnancy are closely related to neonatal birthweight. Pregnancies complicated by gestational diabetes (GDM) are associated with large for gestational age and macrosomia in the neonate, but the relationship between cardiovascular parameters and birth weight in these pregnancies has not yet been explored. Our objective was to investigate how maternal hemodynamics influence neonatal birthweight in pregnancies complicated by GDM, using a causal inference model for analysis. Methods: Maternal hemodynamics were assessed using the Arteriograph ® and bioreactance techniques at 34 +0 -42 +0 weeks of gestation in women with GDM and normotensive non-diabetic controls. Graphical and linear regression models were used to determine causal relationships between measured variables and neonatal birthweight centile. Results: 172 women with GDM and 182 normotensive, non-diabetic controls were included in the analysis. In both groups, increases in maternal cardiac output and body mass index (BMI) produced an increase in neonatal birthweight centile. Increases in aortic augmentation index produced a decrease in birthweight centile which reached significance in the GDM group, but not the controls. The effect of increasing mean arterial pressure (MAP) and pulse wave velocity (PWV) on birthweight centile tended to be positive, although did not reach significance among the control group. Conclusions: The relationship between hemodynamics and neonatal birthweight was similar between women with GDM and healthy controls. The positive relationship between MAP and PWV and neonatal birthweight in this study raises the possibility of an inverse U-shaped relationship between these variables which warrants further investigation.