F. Broughton Pipkin

The fetal outcome in a randomized double‐blind controlled trial of labetalol versus placebo in pregnancy‐induced hypertension

Summary. The effects of labetalol were compared with those of placebo in a multicentre randomized double‐blind and prospective study of 152 patients with mild to moderate, non‐proteinuric pregnancy‐induced hypertension. Labetalol in a dose of 100 mg three times daily, increasing to 200 mg three times daily where required, significantly reduced maternal mean arterial pressure. There was some reduction in preterm delivery, neonatal respiratory distress syndrome and jaundice in the labetalol‐treated group. Intrauterine growth retardation and neonatal hypoglycaemia occurred with the same frequency in both groups. There were no perinatal deaths. Labetalol appears to be an effective agent in the management of mild to moderate pregnancy‐induced hypertension. The data from this study suggest possible advantages and no apparent disadvantages for the fetus during its use.

ANGIOTENSINOGEN : MOLECULAR BIOLOGY, BIOCHEMISTRY AND PHYSIOLOGY

Angiotensinogen is the only known substrate for the enzyme renin. Angiotensin II, the end product of the reaction, is an extremely potent vasoconstrictor and a major determinant of salt and water homeostasis. It is also a growth factor. Angiotensinogen has been identified as a non-inhibitory member of the serine proteinase inhibitor family. Although the most abundant source of plasma angiotensinogen is the liver, the use of Northern blotting and reverse transcriptase PCR techniques has confirmed angiotensinogen mRNA expression in a wide range of tissues, including the kidney, brain, vascular tissue, adrenal gland, placenta and leucocytes. The sequencing of the rat and human angiotensinogen genes has increased our understanding of this protein and its role in physiology and the pathogenesis of human disease. Early observations on the regulation of angiotensinogen are now explicable at the molecular level, with the identification of the core promoter, hormone and acute phase responsive elements and tissue-specific enhancers. The role of angiotensinogen in the aetiology of hypertensive disorders has been tested in transgenic animals, and in case-controlled genetic association and linkage studies. This review examines our current understanding of angiotensinogen, in the light of recent advances.

The effect of maternal labetalol on the newborn infant

Summary. The possibility that placentally‐transferred labetalol might cause sympathetic blockade in the newborn infant was examined by measuring systolic blood pressure, heart and respiratory rates, palmar sweating, blood glucose and the metabolic and vasomotor responses to cold stress. Measurements were made serially over the first 72 h of life in 22 term infants, 11 born to mothers treated with labetalol and 11 carefully matched controls. Infants of mothers treated with labetalol showed a mild transient hypotension which had disappeared within 24 h [mean systolic blood pressure at 2 h, 58·8 (SEM 2·4) mmHg compared with 63‐3 (SEM 3·0) mmHg for controls, P<0·05]. There were no other significant differences between the two groups. It is concluded that labetalol does not cause clinically important sympathetic blockade in the mature newborn infant.

A randomised placebo controlled trial of labetalol in the treatment of mild to moderate pregnancy induced hypertension

Objective To determine the need for, and efficacy of, treatment with labetalol in women with mild‐to‐moderate pregnancy induced hypertension (PIH).

Differential expression and distribution of placental glutathione peroxidases 1, 3 and 4 in normal and preeclamptic pregnancy

UNLABELLED Preeclampsia is a pregnancy-specific condition affecting 2-7% of women and a leading cause of perinatal and maternal morbidity and mortality; it may also predispose the mother and fetus to increased risks of adult cardiovascular disease. The selenoprotein glutathione peroxidases (GPxs) have critical roles in regulating antioxidant status. OBJECTIVES, STUDY DESIGN AND MAIN OUTCOME MEASURES Immunohistochemical measurements of GPx1, GPx3 and GPx4 protein expression were performed on samples taken from three standardised sampling sites between the cord insertion and the periphery of the placenta from 12 normotensive, and 12 preeclamptic women to establish if their expression differed between sampling sites. Total GPx activities were also examined from the three sampling sites of these placentae. RESULTS There were highly significant reductions in overall immunohistochemical staining of all 3 GPxs in the preeclampsia compared to normotensive placentae (GPx1: P=0.016; GPx3: P=0.003; GPx4: P<0.001). Furthermore, graded differences in expression between the standardised placental sampling sites were also found for GPx3 (higher in the inner region, P=0.05) and GPx4 (higher in the periphery, P=0.02) but not GPx1. Placental GPx enzyme activity was also significantly reduced in tissue from preeclamptic women as compared to normotensive women (P=0.007; the difference was more pronounced nearest the cord insertion). CONCLUSIONS We have shown highly significant reductions in expression of all three major classes of GPx in placentae from women with preeclampsia, and distribution gradients in activity, which may relate to the differential oxygenation of regions of the placenta.

Maternal and fetal angiotensinogen gene allele sharing in pre-eclampsia

Objective To compare the angiotensinogen genotypes in normotensive and pre‐eclamptic pregnancies in maternal and fetal samples.

What Is the Place of Genetics in the Pathogenesis of Pre-Eclampsia?

It is most unlikely that there is a single ‘pre-eclampsia (PE) gene’. We are probably looking for a cluster of polymorphisms which, possibly in conjunction with environmental factors, predispose to the development of the condition. Accurate phenotyping is vital for any genetic studies of PE, and since the disease is only clinically-detectable in the second half of pregnancy, is particularly difficult. It is increasingly likely that there is a fetal genetic contribution which can only be examined after birth. Candidate genes examined on the basis of displayed or hypothetical pathophysiological effects, but for which no evidence of association or linkage has been found have included HLA-DRβ, HLA-G, and tumour necrosis factor alpha (chromosome 6), angiotensin-converting enzyme (chromosome 17) and CuZn superoxide dismutase (chromosome 21). Chromosomal exclusion mapping and a pedigree study suggest a role for genes on chromosomes 1, 3, 4, 9 or 18. Two genes concerned with clotting, those for factor 5 and methylenetetrahydrofolate reductase, lie on chromosome 1. Both have polymorphisms present in significantly higher frequency in women with PE, as well as showing functional abnormality. They probably predispose to the development of the condition, without being necessary for it. The angiotensinogen (Aogen) gene also lies on chromosome 1. The renin-angiotensin system may be activated during the early stages of PE and subsequently suppressed. In some populations, a relatively common polymorphism is present in raised frequency in women with PE, but it is also raised in non-pregnant hypertensive subjects. However, it is in partial linkage disequilibrium with another polymorphism which shows significantly distorted transmission from mother to fetus in PE pregnancies. Furthermore, its expression is significantly raised in the decidual spiral arteries; abnormal placentation is a feature of PE. We have also shown that a relatively common polymorphism in the angiotensin AT1 receptor gene (chromosome 3) is associated with raised density of the receptor. Thus far, studies of candidate genes have been on a small scale and have very much reflected the pathophysiological research interests of the investigators. The multifaceted nature of PE and the difficulties of accurate phenotyping require the accumulation of a large, very carefully phenotyped, database. It is hoped that funding will become available this year in the UK to allow the collection of such a database. The introduction of chip technology should allow genome scanning of the resource.It is most unlikely that there is a single ‘pre-eclampsia (PE) gene’. We are probably looking for a cluster of polymorphisms which, possibly in conjunction with environmental factors, predispose to th

Comparison of the alpha and beta blocking drug, labetalol, and methyl dopa in the treatment of moderate and severe pregnancy-induced hypertension.

Twentysix women with pregnancy-induced hypertension have been randomly treated with either labetalol or Aldomet. A more satisfactory control of blood pressure was obtained with labetalol with minimal side-effects. After two weeks of treatment with labetalol renal function had significantly improved with a markedly lower incidence of proteinuria. More patients went into spontaneous labour following labetalol than following Aldomet; the Bishop score was also higher in this group. No adverse effects attributable to labetalol were noted in the baby either ante- or post-natally.

Fortnightly Review: The hypertensive disorders of pregnancy

#### Summary points The hypertensive disorders of pregnancy remain an enigma. Biologically speaking, pregnancy is the time when women are the most important to the species. One feels instinctively that any condition that occurs in between 1 in 7 and 1 in 10 women during the course of their first pregnancy cannot be all bad. And yet, successive reports on confidential inquiries into maternal deaths in the United Kingdom have identified hypertension in pregnancy as the most frequently cited cause of maternal death. I cannot cover the pathophysiology of eclampsia in this brief review. Eclampsia occurs unexpectedly in about one in 2000 maternities in the United Kingdom1 and is therefore difficult to study systematically. More than one third of cases occur before the classic warning signs of both proteinuria and hypertension have been documented, and …

Expression of AT1R, AT2R and AT4R and Their Roles in Extravillous Trophoblast Invasion in the Human

The placental renin-angiotensin system (RAS) is active from early pregnancy and may have a role in placentation. Angiotensin II (AngII) acts via binding to receptor types AT1R and AT2R. Recently smaller peptide members of the angiotensin family have been recognised as having biological relevance. Angiotensin (3-8) (AngIV) has a specific receptor (AT4R) and evokes hypertrophy, vasodilatation and vascular inflammatory response. The aim of this study was to characterise placental expression of AT1R, AT2R and AT4R, and to determine whether AngII and AngIV regulate extravillous trophoblast (EVT) invasion, apoptosis and proliferation. Placental samples were obtained from women undergoing elective surgical termination of pregnancy (TOP) at 8-10 weeks gestation (early TOP), 12-14 weeks gestation (mid TOP) or at delivery following normal pregnancy or with pre-eclampsia (PE). Immunohistochemistry and qRT-PCR were performed to determine placental mRNA and protein expression of AT1R, AT2R and AT4R at all gestational ages. EVT invasion following culture with AngII or AngIV was assessed in early placental tissue using Matrigel invasion assays. Invasion was assessed on day 6 of culture and placental explants were harvested for immunohistochemical analysis of apoptosis and proliferation. The results from qRT-PCR and immunohistochemistry showed placental AT1R expression which did not vary with gestation. The highest levels of expression of AT2R were found in early and mid TOP placentae compared to term pregnancy. Expression of AT4R was increased in term placentae, with a significant reduction in PE placentae. Moreover, culture with AngIV or AngII increased EVT invasion from placental explants, which showed increased trophoblast proliferation and reduced apoptosis. This study has characterised expression of AT4R and AT1R and AT2R in human placenta throughout normal pregnancy and in PE. Both AngIV and AngII may play an important role in normal pregnancy.