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Biomedical subjects

B E Murphy

Publications and source records attributed to B E Murphy.

At least 55 records · Page 3Linked to original sources
PubMed1982

The absorption by the human fetus of intra-amniotically injected cortisol.

The absorption of cortisol from amniotic fluid by mother and fetus is poorly understood. Clarification is desirable since the amniotic route might serve as the optimal means of administering glucocorticoids and other drugs to the fetus when this is warranted. To gain some idea of the extent of the fetal absorption of cortisol, tritiated cortisol was injected intra-amniotically 20 min prior to delivery of four fetuses from 11 to 21 weeks gestational age. The tissues were analyzed for cortisol and some of its unconjugated metabolites. The placenta contained about 4% and the fetus 2% of the injected dose, the bulk of the radioactivity remaining in the amniotic fluid. Cord serum levels of radioactivity varied from 2.8 to 9.3% of the amniotic fluid level. Considerable conversion to cortisone had occurred in many tissues, particularly the placenta, lung and kidney. These results suggest that intra-amniotic injection may provide an efficient means of supplying glucocorticoids to the human fetus.

Amnion↗
PubMed1982

Radioenzymaticassay for some substrates and inhibitors of human placental 11-hydroxysteroid dehydrogenase.

A radioenzymaticassay (REA) is described, using labelled cortisol and a homogenate of human placenta. Steroids which are able to compete with the tracer for conversion to the 11-keto form can be measured. Of these, 11 beta and 11 alpha-hydroxyprogesterone (11 beta-hydroxypregn-4-ene-3, 20-dione), 3 beta, 11 beta-dihydroxypregn-5-ene-20-one, 11 beta, 20 alpha-dihydroxypregn-4-ene-3-one and corticosterone are the most active, while cortisol and prednisolone are moderately active. All other steroids tested competed less than 10% as effectively as 11 beta-hydroxyprogesterone at 50% conversion with no added substrate. The sensitivity was 0.8 ng of 11 beta-hydroxyprogesterone and 5 ng cortisol. Using this REA, preliminary studies were carried out to investigate the endogenous substrates and inhibitors of 11-hydroxysteroid dehydrogenase in human fetal tissues.

Adrenal Cortex↗
PubMed1982

Cortisol-cortisone interconversion in human fetal lung: contrasting results using explant and monolayer cultures suggest that 11 beta-hydroxysteroid dehydrogenase (EC 1.1.1.146) comprises two enzymes.

Since cortisol (F) can influence fetal lung maturation, alterations in its intracellular metabolism may be important. In fetal lung at midgestation, both the in vivo studies of Pasqualini et al. and the in vitro studies of Murphy showed the activity of the enzyme 11 beta-hydroxysteroid dehydrogenase (EC 1.1.1.146) to be strongly oxidative, converting F to its inactive analog cortisone (E). By contrast, Smith et al. observed only reductive activity (E to F) in monolayer cultures. The object of this study was to resolve this discrepancy. Human fetal lung (HFL) of gestational age 9-13 weeks was grown in monolayer cultures or as explants on grids in Ham's F-10 medium plus 10% fetal calf serum and [3H]F and [14C]E (12-20 ng/ml of each). Extracts of media were chromatographed to separate the steroids, and the percent conversion was calculated. Explants converted F to E 20-40% and maintained day 1 levels for at least 7 days of culture. E to F conversion was initially low (1-5%) and rose to 14-20% by the end of culture, corresponding to fibroblast-like outgrowth. In monolayer cultures, which appeared to consist almost entirely of fibroblast-like cells, F to E conversion was less than 10% by 5 days, while E to F conversion steadily increased to 20-85% and plateaued at confluence. Homogenates of fresh tissue demonstrated F to E but no E to F conversion, even in the presence of cofactors. Thus, it appears that when tissue structure is maintained as in the explants, HFL cells oxidize F to E by a unidirectional enzyme; activation of E to F is only expressed by HFL fibroblast-like cells in culture and does not reflect the in vivo situation.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1981

Demonstration of novel compounds in human fetal tissues and a consideration of their possible role in parturition.

A study of a new group of compounds and their possible relevance to human parturition is presented. These compounds behave chemically and chromatographically like steroids and have been tentatively identified as analogues of 11-hydroxypregnenolone. Determined by radioenzymatic assay, highest levels were found in the fetal zone of the fetal adrenal and were about 100 times those of fetal serum. Umbilical cord levels were higher after spontaneous labor than after elective cesarean section or induced labor in premature as well as mature infants. It is hypothesized that a fetal factor distinct from adrenocorticotropic hormone acts on the adrenal cortex, particularly the fetal zone, to stimulate 11 beta-hydroxylation of nonglucocorticoid corticosteroids and that these steroids and their metabolites are excreted via the urine into the amniotic fluid. Thus they would reach the membranes and decidua where they might complete with progesterone for receptor sites, decreasing lysosomal stability with the resultant production of prostaglandins and the onset of labor.

11-Hydroxycorticosteroids↗
PubMed1981

Lack of specificity of cortisol determinations in human urine.

The specificity of 7 different binding proteins (4 antibodies and 3 transins) was investigated in human urine. Pregnant and nonpregnant urine samples were extracted and chromatographed, and values were compared before and after chromatography. Without chromatography, all methods grossly overestimated the amount of cortisol present. Four methods gave higher values than the other 3 even after chromatography, possibly due to cross-reactivity with 20-dihydrocortisone which coelutes in part with cortisol. Interference also occurred in both the less polar and the more polar regions of the chromatograms with all assay systems. Values for a series of 20 urines were closely similar for the RTAs but widely divergent for the RIAs. Close correlations were found for all of the RTAs with each other and with the RIAs if simple methylene chloride extraction was used. A high degree of correlation was also found between extracted and unextracted urine values in the 4 systems studied. Cortisol values by RTA (dog transcortin) after chromatography on Sephadex LH-20 gave mean values of 20.5 +/- 9.7 microgram/day in men, 14.0 +/- 5.7 micrograms/day in cycling women, and 38.0 +/- 24.5 micrograms/day in women in late pregnancy (n = 6 in each group). It is concluded that there is no simple practical method currently available for true cortisol in urine, but that the measurement of adrenal corticoids in urine can afford an accurate reflection of adrenocortical function provided there is no gross metabolic abnormality present and that the normal range is carefully established for each particular method used.

Child↗
PubMed1980

Amniotic fluid thyroid hormone concentrations during human gestation.

AFT4, AFT3, and AFrT3 concentrations were measured in samples from pregnant women between 10 and 43 weeks' gestation. During the first half of pregnancy, AFT4 and AFrT3 concentrations increased progressively, reaching peak levels at 25 to 30 and 17 to 20 weeks, respectively. AFT3 concentrations were low and increased slowly during this stage of pregnancy. During the last half of pregnancy, AFT4 and AFrT3 levels decreased while AFT3 continued to increase. This pattern of change is most likely explained by an increase in 5'-iodothyronine monodeiodinase activity in the fetal compartment. Normal values of amniotic fluid thyroid hormone concentrations as standards of reference for possible prenatal diagnosis of fetal thyroid abnormalities are provided.

Amniotic Fluid↗
PubMed1980

Pitfalls in the assay of cortisol.

Many currently used cortisol assays, including commercially available kits, are validated only for adult serum and may give misleading results when applied to urine, fetal or neonatal serum or amniotic fluid. Evidence for such errors is presented to illustrate the danger and confusion which may result.

Adrenal Hyperplasia, Congenital↗
PubMed1979

Radioassays.

Explore the source record for details and available documents.

Animals↗
PubMed1979

Comparison of glucocorticoid conjugates with other indexes of fetal maturation.

Controversy exists as to whether cortisol acts physiologically to accelerate human fetal lung maturation. Recent data from this laboratory showed that cortisol and corticosterone conjugates (GCS) rise fivefold in anmiotic fluid late in pregnancy and correlate well with the palmitic/stearic (P/S) ratio (r = 0.79). In this study GCS was compared with various tests of fetal maturation. In a series of 38 cases compared with the lecithin/sphingomyelin (L/S) ratio, the GCS and palmitic acid had the highest concurrence (84% agreement), followed by the "shake" test (82%), cortisol (74%), cytology (64%), gestational age determined by ultrasound (63%), and creatinine (47%). The GCS correlate better than cortisol itself, probably because cortisol in amniotic fluid is derived from the chorionic membrane as well as from fetal urine. These observations provide convincing evidence of a physiologic link between fetal lung maturation and alteration in fetal steroid production.

Amniotic Fluid↗
PubMed1978

Conjugated glucocorticoids in amniotic fluid and fetal lung maturation.

While recent studies suggest that cortisol plays a role in lung maturation, conflicting reports have recently appeared relating cortisol in amniotic fluid to indices of lung maturation. the variation in the levels and differences in correlation appear to be due to differences in methodology, principally with respect to cross-reactivity in the radioimmunoassays with the conjugates of cortisol and corticosterone. We have found that the glucocorticoid conjugates correlate better with lung maturation (rs = 0.79) than does cortisol itself (rs = 0.58). This is probably because the conjugates are derived exclusively from the fetal compartment whereas cortisol is also produced by the chorionic membrane. In anencephaly, conjugate levels were very low while cortisol levels were relatively normal. Conjugate levels (mainly sulfates) appear promising as an adjunct to tests of fetal maturation.

Amniotic Fluid↗
PubMed1978

Cortisol production and inactivation by the human lung during gestation and infancy.

The enzyme which interconverts the active hormone cortisol (F) and its biologically inactive analog cortisone (E), viz. 11 beta-hydroxysteroid dehydrogenase, is known to be present in many tissues. In this study, its possible role as a regulator of cortisol concentration in the human lung was investigated. Small amounts of minced tissue were incubated for 2 h at 37 C in the presence of tracer F or E. After extraction, the steroids were chromatographed using Sephadex LH-20 column chromatography. From 11-21 weeks of gestation, inactivation of F to E occurred (54.7 +/- 8.0%), while in 11 premature infants there was no conversion in either direction and in 9 infants (4 months to 2 yr of age) there was slight conversion of E to F (7.0 +/- 3.4%). Activity in children was negligible. Lung tissue from 4 anencephalics (35-40 + weeks) retained the ability to inactivate F to E (21.3 +/- 4.3%), though to a lesser extent (P less than 0.01) than fetuses up to 21 weeks. The validity of these in vitro studies was borne out by assays of the endogenous steroids in lung tissue and serum. These results suggest that there is an alteration from rapid inactivation of F to E in early fetal life to slight F production in infancy and that this change is advanced by pituitary or other factors which are decreased in anencephaly. This decreasing inactivation by the lung during late gestation results in higher intracellular F levels which probably act to promote lung maturation in preparation for birth.

Adolescent↗