Comparison of angiotensin II type 1 receptor blockade and angiotensin-converting enzyme inhibition in pregnant sheep during late gestation.

1. The effects of antagonism of the maternal renin-angiotensin system (RAS) with either an angiotensin II type 1-(AT1) specific receptor blocker (GR138950) or an angiotensin-converting enzyme (ACE) inhibitor (captopril) were compared in chronically-catheterised ewes and their foetuses during late gestation. 2. Daily from 127 +/- 1 days of gestation until parturition at 145 +/- 2 days, each ewe received i.v. either GR138950 (3 mg kg-1; n = 10), captopril (3 mg kg-1; n = 6) or an equivalent volume of vehicle solution (0.9% w/v saline; n = 10). 3. Within 2 h of drug administration, GR138950 abolished the maternal, but not the foetal, pressor responses to angiotensin II (AII; 100-188 ng kg-1, i.v.; P < 0.05), whereas captopril abolished both the maternal and foetal pressor responses to angiotensin I (AI; 400-750 ng kg-1, i.v.; P < 0.05). 4. On the first day of treatment, maternal blood pressure decreased in all GR138950-treated (-21 +/- 4 mmHg; P < 0.05) and captopril-treated (-13 +/- 5 mmHg; P > 0.05) ewes at 2 h after drug administration. Captopril also significantly decreased foetal blood pressure by 5 +/- 1 mmHg (P < 0.05). However, foetal blood pressure in the GR138950-treated animals remained unchanged. Maternal and foetal heart rates were unaffected by any treatment. Uterine blood flow was significantly reduced within 2 h of both GR138950 (-130 +/- 20 ml min-1; P < 0.05) and captopril (-72 +/- 16 ml min-1; P < 0.05) administration. 5. On the first day of treatment, maternal arterial haemoglobin (Hb) concentration and oxygen (O2) content increased at 2 h in all GR138950-treated and captopril-treated ewes. Foetal arterial pH and oxygenation (O2 content, O2 saturation and Pao2) were reduced by a similar extent in both groups of drug-treated ewes. 6. After one week of daily GR138950 administration, maternal blood pressure decreased from a pretreatment value of 96 +/- 5 mmHg on day 1 to 79 +/- 2 mmHg by day 7 (P < 0.05). Captopril treatment had no long-term effect on maternal blood pressure. Although foetal blood pressure increased by 3 +/- 1 mmHg over a week of vehicle treatment (P < 0.05), no significant differences were observed between the long-term changes in foetal blood pressure in all three groups of animals. 7. There were no long-term effects of drug administration on maternal Hb concentration or oxygenation, or on the foetal haematological parameters. However, changes in maternal PaCo2 observed in the GR138950-treated (+1.4 +/- 0.5 mmHg; P < 0.05) and captopril-treated (+3.3 +/- 1.1 mmHg; P > 0.05) ewes were significantly different from those seen in the vehicle-treated animals (P < 0.05). 8. There were no apparent adverse effects of maternal GR138950 or captopril treatment on foetal viability. 9. The present study demonstrated that administration of either GR138950 or captopril to pregnant ewes effectively blocked the maternal RAS, and caused hypotension and a decrease in uterine blood flow. However, only captopril appeared to cross the placenta to influence directly the RAS of the sheep foetus. This suggests that the fall in foetal oxygenation observed after AT1-specific receptor blockade and ACE inhibition originates primarily from changes in the maternal and/or placental vasculature. Despite these changes, neither GR138950 nor captopril were detrimental to the outcome of pregnancy when foetal blood loss was kept to a minimum.

The relative accuracy of mercury, Tempa-DOT and FeverScan thermometers.

This project aimed to assess the accuracy of Tempa-DOT and FeverScan for measuring children's temperatures. Tempa-DOT is a small flat chemical thermometer with 50 dots that change colour at specific temperatures. FeverScan is a liquid crystal strip thermometer with temperature sensitive colour bars that change colour when held against the forehead. Two medical students undertook this study in a hospital in Zambia. They saw most children presented to the hospital over a six-week period and on the children's ward. A mercury thermometer was placed in one axilla, a Tempa-DOT thermometer in the other, and the FeverScan was held on the child's forehead. Data were obtained from 1090 children with a median age of two years. The sensitivity of FeverScan to correctly identify febrile children was 89% and the positive predictive value to detect a fever was 57%. The sensitivity of Tempa-DOT to correctly identify febrile children was 92% and the positive predictive value for detecting febrile children was 86%. Tempa-DOT has a much better predictive value than FeverScan for detecting fever.