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Biomedical subjects

J G Thornton

Publications and source records attributed to J G Thornton.

At least 73 records · Page 4Linked to original sources
PubMed1991

Tables for estimation of individual risks of fetal neural tube and ventral wall defects, incorporating prior probability, maternal serum alpha-fetoprotein levels, and ultrasonographic examination results.

Tables are provided for estimation of the risk of open spina bifida in patients who have elevated maternal serum alpha-fetoprotein levels but normal results on detailed anatomy ultrasonographic scan. Risks are provided for various prior population risks, for various levels of elevated maternal serum alpha-fetoprotein, and for various assumptions about the sensitivity of ultrasonographic examination. The formula used is based on sequential multiplication of odds with the use of Bayes' theorem, but an arbitrary reduction (to the power of 0.5) in the degree to which ultrasonographic information modifies the odds has been made to allow for the nonindependence of ultrasonography and maternal serum alpha-fetoprotein tests. The wide range of resulting risks shows that the decision to offer amniocentesis after a negative scan should be individualized.

Abdominal Muscles↗
PubMed1991

Clinical experience with the triple test for Down's syndrome screening.

The introduction of maternal serological screening for chromosome disorders in pregnancy in women aged over 30 years at the estimated date of delivery was monitored in two hospitals. The test used involved measurement of three substances in maternal serum combined with maternal age (the triple test). This is the first report of such screening applied to an unselected antenatal clinic population. Test uptake was high but there was no overall increase in amniocentesis numbers because the increase in younger mothers was compensated for by a decrease in older women who previously, without serological testing, might have gone directly to amniocentesis. It is anticipated that widespread introduction of such testing will lead to improved detection of Down's syndrome as predicted from retrospective studies.

Adult↗
PubMed1990

Decision analysis in obstetrics and gynaecology.

Decision analysis has its weaknesses: it may oversimplify problems, and probability and utility estimates may be biased. However, the alternative--decision-making by intuition--is likely to oversimplify problems even more and to be subject to even greater bias. Clinicians and patients often ignore major items of data, they handle probabilistic information badly, and their decisions are subject to a number of well-documented biases (Tversky and Kahnemann, 1974). Concern over these problems is not a reason to avoid decision analysis. Probably the greatest virtue of the decision tree and the other components of decision analysis is that the method forces decision-makers to make the bases for their decisions explicit. Generating the information often clarifies problems, and the source of difference of opinion can then be elucidated. Most of the benefits of decision analysis come to the decision-maker in the early part of the analysis as the problem is formulated and probabilities and values are estimated. Only occasionally is it necessary to perform new research, formally measure experts' opinions by the Delphi method, or do elaborate sensitivity analysis.

Bias↗
PubMed1989

Efficacy and long term effects of antenatal prophylaxis with anti-D immunoglobulin.

OBJECTIVE: To measure the safety and efficacy of antenatal treatment with anti-D immunoglobulin. DESIGN: Open study with historical controls. SETTING: Multicentre study in 17 hospitals in West Yorkshire. PATIENTS: 1238 Rh negative women who delivered Rh positive infants after 34 weeks in their first pregnancy in 1980-1 (group 1) and 2000 similar primigravidas from 1978-9 (group 2). Obstetric data were collected for 616 women in group 1 who had a subsequent pregnancy, 536 similar women in group 2, and 410 Rh positive but otherwise similar primigravidas who delivered in the same hospitals in 1978-81 (group C). INTERVENTIONS: Anti-D immunoglobulin 100 micrograms intramuscularly was given at 28 and 34 weeks to the mothers in their first pregnancy who delivered in 1980-1. END POINTS: Detection of anti-D antibody in the first or any subsequent pregnancy in groups 1 and 2. For all three groups having subsequent pregnancies gestation at delivery, birth weight, fetal survival at one month, pre-eclampsia defined as blood pressure greater than 140/90 on two occasions more than 12 hours apart, and proteinuria greater than 0.25 milligram. MEASUREMENTS AND MAIN RESULTS: Antenatal immunisation to Rh(D) occurred in six mothers in group 1 and 32 group 2. Most immunisations occurred in the first or second pregnancy. The rates of abortion, gestation at delivery, birth weight, and fetal survival were not significantly different among the three groups. The incidence of pre-eclampsia was lower in mothers given antenatal anti-D immunoglobulin, but the difference was not significant. CONCLUSIONS: Antenatal prophylaxis with anti-D immunoglobulin is effective, and the effect of giving it in the first pregnancy persists into at least the second pregnancy. It seems to be safe for the fetus in the index and subsequent pregnancies.

Birth Weight↗
PubMed1989

A prospective study of haemostatic tests at 28 weeks gestation as predictors of pre-eclampsia and growth retardation.

A panel of haemostatic tests was performed on 400 primiparous women at 28 weeks to test whether one or more could predict the development of pregnancy complications. Fifteen women subsequently developed pre-eclampsia with significant proteinuria and 13 delivered growth retarded infants. There were no significant differences between mothers in the pre-eclampsia group and 22 randomly selected controls. A stepwise logistic discriminant analysis of the data did not produce a significant model. In the growth retarded group only beta thromboglobulin levels were significantly lower than in the controls (p less than 0.05), although in the logistic discriminant analysis the inclusion of both beta thromboglobulin and fibrin degradation products led to a borderline significant improvement in fit of the model. We conclude that the haemostatic variables studied are not significantly changed at 28 weeks nor clinically useful predictors of either pre-eclampsia or fetal growth retardation.

Female↗
PubMed1989

Measurement of the S-phase duration in normal and abnormal human endometrium by in vitro double labelling with bromodeoxyuridine and tritiated thymidine.

The duration of the S phase of the cell cycle (ts) in the glands and stroma of normal, hyperplastic, and malignant endometrium was measured in vitro using a double labelling technique. Endometrial organ cultures were incubated sequentially in tritiated thymidine (3HTdR) and bromodeoxyuridine (BrdU) each for 1 h. Labelled cells were visualized in tissue sections using 3HTdR autoradiography and immunohistochemistry with an anti-(BrdU) antibody. Three populations of cells, single labelled with either 3HTdR or BrdU, and double labelled cells, were easily identified and ts was calculated from both the rate of influx into, and efflux out of S. There were no significant differences in ts in the different tissue types or between influx and efflux in the glands. However, in the stroma ts calculated from the rate of efflux was significantly shorter than that calculated from the rate of influx, suggesting that during the cell culture period the rate of cell efflux from S was greater than influx. This is the opposite to what would be expected in an exponentially growing cell population and suggests that there may be an effect from the culturing conditions.

Bromodeoxyuridine↗
PubMed1989

Effect of pituitary gonadotrophins on proliferation of primary cultures of human ovarian stroma.

Proliferation of ovarian stromal cells is a common phenomenon in peri- and post-menopausal ovaries. It is generally assumed to be secondary to the rise in circulating gonadotrophins at the menopause, though the process by which it occurs is poorly understood. This study aimed to examine the effect of menopausal levels of pituitary gonadotrophins on the growth of primary cultures of ovarian stroma. A culture system was developed using primary explants of ovarian stroma on a collagen substrate. The effect of follicle stimulating hormone (FSH; 10(-5) g/l) and luteinizing hormone (LH; 10(-5) g/l) on the proliferation of cultures derived from the cortices and medullae of ten ovaries was evaluated using a dual radiothymidine labelling technique. FSH was stimulatory to cortical cultures from 9/10 ovaries and medullary cultures from 7/10 ovaries, while LH was stimulatory to cortical cultures from 6/9 ovaries and medullary cultures from 5/10 ovaries. The responsiveness of the cultures did not correlate with the degree of hyperplasia in vivo. This study demonstrates that pituitary gonadotrophins may modulate the growth of stromal cells in culture, and thus may play a role in the process whereby stromal proliferation occurs in peri- and post-menopausal ovaries.

Adult↗