Manpower: a junior's view.
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Health Policy↗
Biomedical subjects
I A Greer
Publications and source records attributed to I A Greer.
Synergistic inhibitory effects of adrenoceptor antagonists and prostacyclin, and umbilical artery-derived prostacyclin-like activity on platelet aggregation.
Adrenoceptor antagonists are being used increasingly for the treatment of pregnancy-induced hypertension (PIH). Previous studies have shown that these drugs can inhibit platelet aggregation and thromboxane production. The aims of this study were to determine (i) whether adrenoceptor antagonists had any effect on vascular prostacyclin (PGI2) production and (ii) whether these drugs acted synergistically with PGI2 and the PGI2-like activity derived from umbilical artery to inhibit platelet aggregation in vitro. The adrenoceptor antagonists labetalol, pindolol and propranolol were found to have no effect on PGI2 production from the umbilical artery at low drug concentrations. These agents were also found to act synergistically with both pure PGI2 and PGI2-like activity derived from umbilical artery to inhibit platelet aggregation. This synergistic effect may be beneficial in the treatment of disorders which are associated with reduced PGI2 production, such as PIH where such synergy may help compensate for PGI2 deficiency.
6-Ketoprostaglandin F1 alpha↗
Nitric oxide concentrations are increased in the feto-placental circulation in intrauterine growth restriction.
The aim of this study was to measure plasma concentrations of total nitrites, as an index of nitric oxide (NO) synthesis, in the fetal circulation of normal pregnancies and in pregnancies complicated by intrauterine growth restriction. Plasma was prepared from umbilical venous blood collected from 13 placentae from normal pregnancies complicated by intrauterine growth restriction. Plasma NO concentrations were determined using the Greiss reaction by measuring combined oxidation products of NO, plasma nitrite (NO2-) and nitrate (NO3-) after reduction with nitrate reductase. Significantly higher NO2-concentrations were found in umbilical venous plasma in the group complicated by intrauterine growth restriction compared to the control group (65.6 mumol/1, P < 0.001. These results support the hypothesis that increased NO production may be a compensatory response to improve blood flow in the placenta and/or may play a role in limiting platelet adhesion and aggregation.
Adult↗
Treatment of endothelial cells with serum from women with preeclampsia: effect on neutrophil adhesion.
OBJECTIVE: The purpose of our study was to determine whether the previously reported neutrophil activation that occurs in the maternal circulation of women with preeclampsia is due to a factor (or factors) in serum that increases neutrophil adhesion to endothelial cells. METHODS: The extent of neutrophil adhesion to endothelial cells incubated with serum from women with preeclampsia (n = 12) was compared with serum from normal, pregnant women matched for maternal age and gestational age at blood sampling (n = 12). Preeclampsia was defined as persistent diastolic blood pressure above 90 mmHg, with proteinuria greater than 0.3 g per 24 hours, in patients who were normotensive before 20 weeks' gestation. The ability of serum (with and without heat inactivation of the complement system) from both groups of patients to stimulate neutrophil adhesion to endothelial monolayers was tested in a 15-minute quantitative assay using fluorescence-labeled neutrophils. The extent of neutrophil adhesion was quantified indirectly from fluorescence counts. RESULTS: No significant differences were found regarding neutrophil-endothelial cell adhesion in response to media alone, serum from women with preeclampsia, and serum from normal, pregnant women. This was also the case when the serum was heat inactivated to destroy the complement system. However, heat inactivated serum produced a significantly greater extent of adhesion compared with serum containing an intact complement system, regardless of whether the patient had preeclampsia. CONCLUSION: This study found no evidence of a factor in serum from women with preeclampsia that could alter neutrophil-endothelial cell adhesion via a direct effect on the endothelium. However, our data suggest that adhesion may be regulated in an inhibitory manner by the complement system.
Adult↗
The transfer of prostaglandin E2 across ovine fetal membranes in vivo.
OBJECTIVE: This study investigated whether prostaglandin E2 (PGE2) can cross intact fetal membranes in vivo. METHODS: We have developed a novel ovine model using in vivo dialysis systems, positioned between the fetal membranes and decidua and in the amniotic cavity. Sheep were given 25 microCi, 50 ng [3H]PGE2 or 1 mg PGE2 to the amniotic cavity, and radioactivity or PGE2/PGEM concentrations in dialysates were determined. RESULTS: Endogenous basal PGE2 concentrations were significantly higher in extra-amniotic than in intra-amniotic dialysates (715 +/- 436 versus 80 +/- 31 pg/mL; mean +/- standard error of the mean; P < .05). After injection of [3H]PGE2 into the amniotic cavity, no radioactivity was detected in the extraamniotic dialysate, and this was not influenced by labor induced by ACTH administration to the fetus. In contrast, intra-amniotic injection of 1 mg PGE2 resulted in marked transfer of PGE2 across the fetal membranes to the extra-amniotic dialysis system. CONCLUSION: These results suggest that PGE2 can cross the ovine fetal membranes in vivo, escaping metabolism in the chorion.
Adrenocorticotropic Hormone↗