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Biomedical subjects

F D Johnstone

Publications and source records attributed to F D Johnstone.

At least 73 records · Page 4Linked to original sources
PubMed1988

Umbilical artery Doppler waveform in pregnancies with uncomplicated intra-uterine growth retardation.

Seventy-four pregnancies with uncomplicated intra-uterine growth retardation were assessed at the time of diagnosis by Doppler ultrasound umbilical artery flow velocity waveform. The results were not disclosed to the clinicians. Only those pregnancies with a complete absence of pre-existing disease or pregnancy complications were included. Ten patients showed evidence of fetal compromise due to asphyxia either before or during labour. In all cases the umbilical artery flow velocity waveform had been abnormal, and this abnormality always preceded cardiotocogram abnormality by up to 5 weeks. Though the resistance index was significantly associated with birth weight (p less than 0.001), this relationship was clearly dependent on the compromised fetuses who tended to be very small, and the true association is probably between resistance index and compromise, with birth weight being an intervening variable.

Adult↗
PubMed1988

The effects of placental site on the arcuate artery flow velocity waveform.

Eighty-three consecutive patients were studied to determine the effect of placental site on the arcuate artery flow velocity waveform. The resistance indices derived from signals obtained from the placental side of the uterus were significantly lower than those derived from signals obtained from the nonplacental side. Doppler studies of the uteroplacental circulation should be performed preferably with knowledge of the placental site.

Arteries↗
PubMed1987

Maternal posture in second stage and fetal acid base status.

The effect of position during the second stage on outcome was studied in 58 women, with no exclusions because of pregnancy complications or signs of fetal distress, who were randomly allocated to have the second stage conducted in either the dorsal or 15 degrees lateral tilt position. All the women were of parity 0 or 1 and the two groups were well matched except for gestational age at delivery. There were no differences in clinical outcome between the two groups, but overall the dorsal group had lower cord artery pH values (P less than 0.05), higher PCO2 (P less than 0.01) and a greater base deficit, but not significantly so. pH and base deficit were similar in both groups where the second stage did not last greater than 15 min. Thereafter, there was a trend to decreasing pH and increasing base deficit with increasing length of second stage in the dorsal group, but not in the tilt group though this did not reach statistical significance. Low Apgar scores, complicated pregnancy and first pregnancy were each associated with significantly lower pH levels. Prolonged placement of the patient in the flat dorsal position should be avoided in second stage, though a suitable alternative under the conditions described has not been defined.

Adult↗
PubMed1987

Umbilical artery reactivity and ultrastructural changes in pregnancy-induced hypertension and other complicated pregnancies.

Abnormal pressor responses are known to occur in the maternal circulation in pregnancy-induced hypertension (PIH), but little is know of the response of the foetal circulation. The responsiveness of umbilical arteries in PIH can be studied after delivery, and this is a useful model to explore the pathophysiological mechanisms involved. In the present experiments, the in vitro response of umbilical artery rings to bradykinin and 5-hydroxytryptamine (5-HT) was tested and ultrastructural changes investigated. Umbilical arteries from 48 cords were studied. Fifteen of the mothers had PIH, five had essential hypertension pre-dating the pregnancy and five had diabetes. Twenty-three women had pregnancies uncomplicated by hypertension or serious medical or obstetric problems and these served as controls. Umbilical arteries from the severe proteinuric PIH group were significantly more responsive to 5-HT as assessed by affinity constants (P less than 0.05). The responsiveness of arteries from all other groups did not differ from the normal cases. A probable mechanism for the findings is endothelial damage as a result of pre-eclamptic disease. This was substantiated by ultrastructural evidence.

Adult↗
PubMed1984

Insulin action and pharmacokinetics in insulin treated diabetics during the third trimester of pregnancy.

Insulin action and pharmacokinetics were compared, using the euglycaemic insulin clamp technique, in seven insulin-treated diabetics during the third trimester of pregnancy and one to three weeks post-partum. At an insulin infusion rate of 1 mU/kg/min, insulin mediated glucose disposal was significantly greater (p less than 0.02) following delivery (1.194 +/- 0.138 mmol/m2/min) than in pregnancy (0.761 +/- 0.072 mmol/m2/min) and the rate of decline in insulin mediated glucose disposal, at the end of the insulin infusion, was significantly greater (p less than 0.02) following delivery (24.78 +/- 4.22 mumol/m2/min2) than in pregnancy (15.17 +/- 2.00 mumol/m2/min2). The metabolic clearance rate, distribution space and pharmacological half-life of insulin were not significantly altered by pregnancy. These findings show that the third trimester of pregnancy is associated with steady state insulin resistance accompanied by a reduced rate of insulin deactivation, but normal insulin pharmacokinetics.

Adult↗
PubMed1981

Nitrogen balance studies in human pregnancy.

Sixty-eight primigravidae successfully complete a 12-day nitrogen balance study when they were between 30 and 34 weeks pregnant. Particular attention was paid to ensure that each patient ate a hospital diet quantitatively equal to the home diet; each patient ate the same every day and all food was eaten. There was a significant correlation between nitrogen intake and apparent nitrogen retention but no relationship between apparent nitrogen retention and birth weight or the occurrence of pre-eclampsia. The mean apparent nitrogen retention for the 68 women was 1.2 g/day. Once allowance is made for integumental losses this figure is equal to the estimated daily nitrogen retention for growth of the fetus and reproductive tissues during this time. There was no evidence of maternal storage of surplus protein as has been previously suggested. The previous literature is reviewed and an attempt made to explain the discrepancy between the findings in this study and previous work.

Birth Weight↗
PubMed1977

Fetal proteinuria in diagnosis of congenital nephrosis detected by raised alpha-fetoprotein in maternal serum.

High concentrations of alpha-fetoprotein (alpha-FP) were found at 14, 19, and 21 weeks gestation in the serum of a woman with a history of unexplained fetal death in her previous pregnancies. The alpha-FP concentration of the liquor also was high at 21 weeks and the pregnancy was terminated. Though the fetus was macroscopically normal, measurement of albumin, alpha-FP, IgG, and alpha2-macroglobulin in the fetal urine showed a selective proteinuria, and congenital nephrosis was diagnosed after examination of the fetal kidneys by electron microscopy. Possibly some fetuses reported to be "false-positive for neural tube defect" may have had renal lesions of this nature. Examination of fetal urine may be the simplest initial diagnostic procedure in any future case.

Adult↗
PubMed1976

Cervical diameter after suction termination of pregnancy.

The diameter of the internal cervical os was measured in several groups of patients in an attempt to assess any damage caused by suction termination of pregnancy. Pregnant women who had had a previous abortion by vacuum aspiration had significantly greater cervical diameters than those who had not, and there was a statistically significant correlation between dilatation of the cervix at operation and cervical diameter at six weeks' follow-up. Cervical dilatation to 10 mm or less was subsequently associated with a normal cervical diameter, but the diameter was often large when the extent of dilatation was greater than 12 mm or not known. Cervical dilatation at termination of pregnancy should, if possible not exceed 10 mm.

Abortion, Induced↗