E. M. Symonds

PREVALENCE OF LUMBAR DISC DEGENERATION OBSERVED BY MAGNETIC RESONANCE IN SYMPTOMLESS WOMEN

302 women aged 16-80 without symptoms of spinal disease had their lumbar intervertebral discs examined by magnetic resonance. The prevalence of one or more degenerate discs increased linearly with age but disc degeneration was already present in over one-third of women aged 21-40; these young women may prove to be at special risk of disc prolapse later in life. The high prevalence of symptomless disc degeneration must be taken into account when magnetic resonance is used for assessment of spinal symptoms.

The effect of captopril (SQ14,225) upon mother and fetus in the chronically cannulated ewe and in the pregnant rabbit.

1. An inhibitor of angiotensin‐I‐converting enzyme activity (D‐3‐mercapto‐2‐methylpropanoyl‐L‐proline, Captopril) was given to five chronically cannulated pregnant ewes and eleven rabbits in late pregnancy. 2. Within 2 min of administration to the sheep, Captopril had blocked the maternal conversion of angiotensin I to II, as assessed by the pressor response evoked by the i.v. administration of angiotensin I. Maternal and fetal basal systemic blood pressures had fallen within 10 min of administration. Although maternal systemic blood pressure returned to basal levels within 2 hr, fetal pressures remained low for up to 2 days. 3. All ewes went into spontaneous labour at or near term. One lamb was live‐born but very weak and failed to establish suckling. The remaining seven lambs were fresh still‐births. 4. Gestation length was significantly prolonged in the treated rabbits by comparison with ten controls. The still‐birth rate was 37% in the treated animals and 6% in the controls (P less than 0.001). 5. It is concluded that the administration of Captopril to the two species studied is harmful to the fetus. The observations suggest that the drug rapidly crosses the placenta, and may cross the blood‐brain barrier to exert a central effect. It may also interfere with the normal initiation of parturition.

Can fetal electrocardiography improve the prediction of intraparturn fetal acidosis

Summary. An outline is given of a computer‐based system which continuously enhances and measures the waveform of the intrapartum fetal electrocardiogram. This system has been used to examine the behaviour of the ST segment and T wave in a group of 14 fetuses where the outcome was biochemically and clinically normal, and in a group of 10 fetuses which were acidotic at birth. When the mean values in each group were compared, highly significant differences were found for both of these components of the waveform. These differences have also been demonstrated by the analysis of long‐term trends in the behaviour of these variables. The highly significant correlation between both a long‐term increase in ST segment and T wave height and fetal acidosis, found in this study, reflects earlier work by others in the experimental animal fetus. The findings suggest that continuous monitoring of the waveform of the fetal electrocardiogram in labour may give a much better prediction of fetal acidosis than is currently achieved with the monitoring of heart rate alone.

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).

Magnetic resonance imaging (MRI) in obstetrics. I. Maternal anatomy

Summary. We assessed the ability of magnetic resonance, a recently introduced imaging technique, to demonstrate the maternal anatomy in obstetrics. The signal intensity of different maternal tissues using T1 and T2 weighted sequences was examined. The bony pelvis is depicted with sufficient clarity to provide an alternative to conventional X‐ray pelvimetry. The placenta and cervix have a distinctive appearance facilitating the diagnosis of placenta praevia. The unique demonstration of cervical morphology will offer the potential for investigation into the illunderstood conditions of cervical dystocia and cervical incompetence.

The effects of intravenous angiotensin II upon blood pressure and sodium and urate excretion in human pregnancy.

Twelve women in their first 3 months of pregnancy received an i.v. saline load (3 mmol sodium/kg) and a graded infusion of angiotensin II (Ang II; i.e. 4, 8 and 16 ng/kg per min). As controls, twelve comparable pregnant subjects received the saline infusion alone. Eight non-pregnant women underwent both protocols, with doses of 2, 4 and 8 ng/kg per min Ang II, and thus acted as their own controls. Saline loading evoked proportionately similar falls in basal plasma renin (PRC) and plasma aldosterone (PAC) concentrations in pregnant and non-pregnant women. Angiotensin II evoked a dose-dependent pressor response, a graded increase in PAC and a reduction in sodium and urate excretion in both pregnant and non-pregnant women. The administration of Ang II had a proportionately greater effect on sodium and urate excretion in non-pregnant than in pregnant women; the pressor response to Ang II was also decreased in the pregnant women. The stimulation of PAC by Ang II, however, did not differ between the two groups. These results show that refractoriness to the renal and vascular effects of Ang II is present as early as the eleventh week of gestation. They also support the hypothesis that there is a degree of dissociation between the renin-angiotensin system and PAC in normal pregnancy.

Production of active and inactive renin by cultured explants from the human female genital tract

Summary. Myometrium, decidua, chorio‐decidua and amnion were collected from women undergoing caesarean section and from pregnant women at hysterectomy and hysterotomy for comparison with myometrium, cervix and endometrium taken from non‐pregnant women at hysterectomy. Homogenates of chorio‐decidua and amnion contained the largest concentrations of active and inactive renin. Cultured explants of all tissues except amnion were found to produce both types of renin. The percentage of active renin produced before 20 days of culture was significantly greater in cultures of chorio‐decidua than in those of myometrium (P < 0,0005) or decidua Vera (P< 0.029, which suggests that renin synthesis in vivo is probably confined to the chorio‐decidua.

A randomized placebo‐controlled study of the effect of low dose aspirin on platelet reactivity and serum thromboxane B2 production in non‐pregnant women, in normal pregnancy, and in gestational hypertension

Objective To investigate the effect of 60 mg aspirin daily on platelet reactivity and prostaglandin production in various groups of patients. Similar regimens, which are thought to act through inhibition of platelet thromboxane production, are currently undergoing clinical assessment for the prevention of pre‐eclampsia and intrauterine growth retardation.

Atrial natriuretic peptide and atrial size during normal pregnancy

Summary. Plasma atrial natriuretic peptide (ANP), right and left atrial areas and the diameter of the left atrium were studied serially during normal pregnancy and at 6 weeks post partum in 21 nulliparous women. Concentrations of ANP in plasma were significantly elevated during mid‐pregnancy. Thereafter ANP levels were not significantly different from those at 6 weeks after delivery. All atrial measurements were significantly increased in the third trimester of pregnancy, but none was significantly correlated with the plasma ANP concentrations. This might point at an altered mechanism of ANP secretion, which may be part of a physiological adaptive process to sustain the hypervolaemia of pregnancy.

Generation of angiotensin I by human chorion-decidua in vitro

An angiotensin I-like substance has been detected in media after incubation of human chorion-decidua in vitro. The substance was identified as angiotensin I by gel filtration, ion exchange chromatography, and a specific antiserum to angiotensin I. The presence of angiotensin I in these incubates indicates that renin substrate may be either stored or synthesized by the tissue. The levels of angiotensin I produced during incubation were greater than could be explained by the action of renin on plasma substrate since the major part of the chorion-decidua is avascular. Previously chorion-decidua has been shown to contain large amounts of renin and to be capable of synthesizing both active and inactive forms of the enzyme in vitro; however, renin substrate has not been described in this tissue.