High oestrogen excretion in pregnancy

Summary. Fifty-one women with singleton pregnancies whose urinary oestrogen excretion was above the 95th centile of the hospital's reference range on two or more occasions were reviewed. The women did not differ from the general population in race, parity, age, height or weight gain during pregnancy, but they were slightly heavier. Fetal and placental weights were greater than the corresponding values in the general population, as were the volumes of urine containing the oestrogen, but none of these differences was sufficient to account for oestrogen excretion above the 95th centile. Eleven patients, has a glucose tolerance test, two of them had abnormal results and nine had normal results but heavy babies. Patterns of oestrogen excretion did not identify a high-risk population but the women with consistently high excretion gave birth to eight of the nine babies that weighed 4 kg in this population. Twenty-two of the women had 23 subsequent pregnancies in which oestrogen excretion was measured: excretion was normal in 17, low in two and above the 95th centile in four.     

Lorazepam premedication for labour

Summary. Fifty primigravidae were given either lorazepam (2 mg) or identical dummy tablets in early labour, in a randomized double-blind fashion. Analgesia (standardized at pethidine 100 mg) was given as required, and pain relief was assessed by visual analogue scales. Analgesia was significantly better in those mothers who had received lorazepam. There was a higher incidence of respiratory, depression at birth in the infants in this group, although this was not statistically significant. Patients given lorazepam were all satisfied with their analgesic regimen compared with half of those given an inactive tablet. There was a higher incidence of amnesia for labour in the active group. There is a need for a similar study of the effects of other drugs which arc given to supplement pethidine in labour.     

Lipoprotein lipase.

The activity of lipoprotein lipase in the vascular bed represents the major pathway by which triglyceride fatty acid is cleared from the plasma and made available to the epripheral tissues. Recent studies on the properties of the enzyme, both solubilized and membrane-bound have provided new information on the regulation of its activity with the major triglyceride-rich lipoprotein substrates. A key role for this enzyme in the regulation of plasma triglyceride levels is indicated from studies of lipase levels in human adipose tissue and in blood plasma obtained after injection of heparin.     

Discoidal bilayer structure of nascent high density lipoproteins from perfused rat liver.

Rat livers were perfused for 6 h without added plasma proteins using washed erythrocytes and buffer in a recirculating system. An inhibitor to the enzyme lecithin-cholesterol acyltransferase (5,5'-dithionitrobenzoic acid) was added in some experiments to prevent modification of substrate-lipids contained in secreted lipoproteins. The inhibitor did not detectably alter hepatic ultrastructure or gas exchange, but it inhibited the secreted lecithin-cholesterol acyltransferase by more than 85%. Very low density lipoproteins in perfusate were unaltered but the high density lipoproteins obtained from livers perfused with the inhibitor appeared disk-shaped in negative stain by electron microscopy with a mean edge thickness of 46 +/- 5 A and a mean diameter of 190 +/- 25 A. The high density lipoproteins were composed predominantly of polar lipids and protein with only small amounts of cholesteryl esters and triglycerides. The major apoprotein of these discoidal fractions had the same electrophoretic mobility as the arginine-rich apoprotein, whereas plasma high density lipoproteins contained mainly the A-I approtein. In all these respects the discoidal perfusate high density lipoproteins closely resemble those found in human plasma which is deficient in lecithin-cholesterol acyltransferase. Perfusate high density lipoproteins obtained in the absence of the enzyme inhibitor more closely resembled plasma high density lipoproteins in chemical composition (content of cholesteryl esters and apoproteins) and in electron microscopic appearance. Purified lecithin-cholesterol acyltransferase synthesized cholesteryl esters at a substantially faster rate from substrate lipids of perfusate high density lipoproteins than those from plasma. The discoidal high density lipoproteins were the best substrate for this reaction. Thin sections of plasma high density lipoproteins indicated a spherical particle whereas discoidal high density lipoproteins stained with the characteristic trilaminar image of membranes. These observations suggest that the liver secretes disk-shaped lipid bilayer particles which represent both the nascent form of high density lipoproteins and preferred substrate for lecithin-cholesterol acyltransferase.