Search PubMed⌕ Search

Biomedical subjects

B E Murphy

Publications and source records attributed to B E Murphy.

At least 37 records · Page 2Linked to original sources
PubMed1989

The influence of various steroids on the binding of methyltrienolone (R1881) to human placenta: evidence for a second steroid-binding site which stabilizes the R1881 binding site.

Specificity studies of the binding of R1881 to crude placental homogenate gave surprising results in that certain steroids increased the binding of [3H]R1881 rather than displacing it. While data for 'competing', i.e. displacing, steroids were similar to those reported by other authors, there have been no previous reports of increased binding due to added steroids. This increased binding was due mainly to an increase in capacity (about 10-fold). These data suggest that the placental steroid-binding protein is unusual in that there is a second steroid-binding site whose occupancy increases the stability of the protein, thereby increasing its capacity to bind R1881.

Androstane-3,17-diol↗
PubMed1989

Identification of 20 alpha-hydroxy-5 alpha-pregnan-3-one and 20 beta-hydroxy-5 alpha-pregnan-3-one in human pregnancy urine.

20 beta-Hydroxy-5 alpha-pregnan-3-one and 20 alpha-hydroxy-5 alpha-pregnan-3-one were isolated and identified from a pool of urine collected from women in the third trimester of pregnancy. Following isolation by Sephadex LH-20 and HPLC, the identity of each compound was established by comparison of GC-MS data for the methyloxime-trimethylsilyl ethers with those for authentic standards.

Chromatography, High Pressure Liquid↗
PubMed1989

Low polarity ligands of sex hormone-binding globulin in pregnancy. Part I--Characterization.

Certain previously unidentified substances of low polarity binding to the sex hormone binding globulin (SHBG) in pregnancy were investigated. This material consisted of four major peaks (designated 1a, 1b, 2 and 3) as defined in maternal serum on Sephadex LH-20 chromatography. They were characterized with respect to changes in their concentration at various gestational ages and at premature and term labour in maternal serum, cord serum, placenta and maternal urine. Levels were much higher in placenta than in serum, suggesting that all four peaks were of placental origin. In the serum of mothers not in labour, while there was a significant increase in the mean serum concentration of peak (1a + 1b) and peak 3 for 12-24 weeks to 30-38 weeks gestation, there was no significant difference in the mean level of peak 2. However, there was a significant decrease in the serum levels of peak 2, but not peaks (1a + 1b) and 3, from 30-38 weeks gestation to 39-41 weeks gestation (P less than or equal to 0.05). In the serum of mothers in premature labour (30-38 weeks gestation), the levels of peak 2 but not those of peak (1a + 1b) and 3, were decreased (P less than or equal to 0.01) compared to those not in labour. These findings are consistent with the identification of peak 1a as 5 alpha-dihydroprogesterone, peak 1b as progesterone and peak 3 as 2-methoxyestrone as described in part 2. The decrease in the levels of peak 2 (for which the identification remains unconfirmed) in association with premature and impending term spontaneous labour suggest that it may be involved in the maintenance of pregnancy.

Chromatography↗
PubMed1989

Low polarity ligands of sex hormone-binding globulin in pregnancy. Part II--Identification.

Certain previously unrecognized ligands of SHBG of low polarity in pregnancy were identified. They include two weakly bound compounds: 5 alpha-pregnane-3,20-dione and progesterone; and two strongly bound substances, 2-methoxyestrone and a new steroid, estradienolone (17 beta-hydroxy-1,5-estradiene-3-one). The identification of the first three peaks was based on chromatographic elution patterns, binding characteristics and gas chromatography-mass spectrometry. The identification of the fourth peak, the new steroid, was based on similar kinds of evidence and, in addition, solubility characteristics and ultraviolet absorption spectrum.

5-alpha-Dihydroprogesterone↗
PubMed1988

The effects of various hormones on human chorionic gonadotropin production in early and late placental explant cultures.

Although human chorionic gonadotropin production peaks in early pregnancy, little is known of the factors regulating it at this time. We have compared human chorionic gonadotropin output in placental explants of 6 to 12 and 37 to 40 weeks' gestational age after addition of hormones on days 4 and 5 of 8 days of culture. Human chorionic gonadotropin production was sevenfold greater in early versus late cultures. In early cultures human chorionic gonadotropin output was increased threefold to fourfold by progesterone, dehydroepiandrosterone, and cortisol whereas late cultures responded only to progesterone and dehydroepiandrosterone. The output of combinations of steroids was additive or better (up to fifteenfold). Gonadotropin-releasing hormone increased human chorionic gonadotropin output only slightly (onefold to twofold) while testosterone was inhibitory (early) or ineffective (late). Estradiol had no effect. These studies demonstrate that explants of early placental tissue provide a useful model for study of human chorionic gonadotropin production, that there are many similarities but some clear differences between early and late secretion, and that steroids exert significant effects on human chorionic gonadotropin production of placental cultures.

Chorionic Gonadotropin↗
PubMed1988

Profiles of ligands of sex hormone binding globulin in human serum.

Ligands of the sex hormone-binding globulin (SHBG) in samples of human serum were extracted into diethyl ether and the dried extracts chromatographed using Sephadex LH-20 chromatography. The resulting fractions were assayed by competitive binding to SHBG against a testosterone standard. Values for dihydrotestosterone and testosterone were similar to those obtained using radioimmunoassay. While the bulk of the material in male and non-pregnant female serum corresponded to other known ligands (5-androstane-3 alpha,17 beta-diol and 5-androstene-3 beta,17 beta-diol), the quantities of material in the androstanediol and androstenediol regions exceeded the known values for these steroids in hirsute women and in late pregnancy, suggesting the presence of other steroids as well. In addition, there was a large amount of material of low polarity present in pregnancy which was not accounted for by recognized circulating ligands. A normal pattern was found in a man with Addison's disease, suggesting that the bulk of SHBG ligands in men are derived from the testis. This was also indicated by the 60-fold higher levels of testosterone and androstenediol seen in normal testicular vein serum. High values of testosterone, androstanediol and androstenediol in a woman with untreated 21-hydroxylase deficiency suggested that large amounts of these compounds (or their precursors) can be produced by the adrenal and that their production by the adrenal is regulated at least in part by ACTH.

Adult↗
PubMed1987

The effects of human chorionic gonadotropin on growth and steroidogenesis of the human fetal adrenal gland in vitro.

This study examined the effects of human chorionic gonadotropin, adrenocorticotropin, human luteinizing hormone, and mouse epidermal growth factor on growth (thymidine incorporation) and steroidogenesis (dehydroepiandrosterone sulfate production) of human fetal zone adrenal cells in monolayer culture. Two preparations of human chorionic gonadotropin extracted from pregnancy urine were used, one highly purified (National Institutes of Health, CR-121) and one less pure (Sigma). Thymidine incorporation was increased twofold to tenfold in cultures exposed to the Sigma human chorionic gonadotropin preparation or to mouse epidermal growth factor as compared to control. Pure National Institutes of Health human chorionic gonadotropin and luteinizing hormone had no effect on growth. When adrenocorticotropin was added alone or in combination with Sigma human chorionic gonadotropin or mouse epidermal growth factor, growth was decreased. Dehydroepiandrosterone sulfate production was stimulated by adrenocorticotropin but not by human luteinizing hormone, human chorionic gonadotropin, or mouse epidermal growth factor. These results suggest that human pregnancy urine contains a growth factor which remains to be identified but that pure human chorionic gonadotropin has no mitogenic or steroidogenic effects on the cultured fetal zone cells of the human fetal adrenal gland.

Adrenal Glands↗
PubMed1987

Contrasting effects of 5 alpha- and 5 beta-pregnane-3,20-dione on the motor activity of ovariectomized rats.

While progesterone metabolites have long been known to be potent anesthetics in pharmacological doses, there is no available information as to their effects on behaviour at physiological levels. In this study, 5 alpha- and 5 beta-pregnanediones in silastic capsules were implanted in ovariectomized rats. Approximately 4 mg/kg/day was absorbed over a 24-day period. Rats receiving 5 beta-pregnanedione had decreased motor activity (58% control, P less than or equal to 0.001) while those receiving the 5 alpha-isomer had increased activity (143% control, P = 0.01). These studies suggest that these progesterone metabolites may be responsible for some behavioural changes.

5-alpha-Dihydroprogesterone↗
PubMed1987

One-tube radiotransinassay for determination of cortisol at ambient temperature.

After extraction of the sample (on filter paper) in the counting vial, cortisol is assayed by adding 50 microL of horse serum containing tritiated cortisol, and 2 mL of toluene scintillator, shaking for 20 min, and counting the radioactivity in a liquid-scintillation counter at ambient temperature. The method can be applied to saliva, serum, or urine--directly as wet samples or dried on the filter paper. Only inexpensive reagents, which are stable for months to years, are needed.

Animals↗
PubMed1986

Relative binding of certain steroids of low polarity to human sex hormone-binding globulin: strong binding of 2-methoxyestrone, a steroid lacking the 17 beta-OH group.

The cross-reactivities for binding sites on human sex hormone-binding globulin (SHBG) of a number of steroids of low polarity, including progesterone and estrogen metabolites, were studied. Binding relative to testosterone (100%) was low (less than or equal to 3%) except for 2-methoxyestrone (81%), 3-acetoxyestradiol (16%), 4-methoxyestradiol (6%), 3 beta-hydroxy-5 beta-pregnan-3-one (5.8%), 5 alpha-dihydrodeoxycorticosterone (4.5%), deoxycorticosterone (4%), 20 alpha-hydroxy-5 alpha-pregnan -3-one (4%), 4-methoxyestrone (4%) and 5 alpha-dihydroprogesterone (3.5%). 2-Methoxyestrone is the only steroid lacking a 17 beta-hydroxyl group which binds to SHBG with strong affinity.

Binding, Competitive↗
PubMed1986

In vitro demonstration of in utero larval development in an oviparous parasitic nematode: Haemonchus contortus.

The life-cycle of Haemonchus contortus, a pathogenic stomach nematode of sheep, is typical of those of the other members of the superfamily Trichostrongyloides, all of which require a period of development outside the definitive host. Classically, gravid H. contortus, known as strictly oviparous, releases her eggs into the abomasal lumen. The eggs are passed out in the faeces in which they hatch into the 1st-stage larvae and then develop into the infective 3rd-stage larvae. We have developed a method to study the fate of eggs within gravid worms. Using this procedure, we have shown that H. contortus may also exhibit viviparity with apparently normal development from the egg to the 4th larval stage taking place within the gravid female maintained in vitro. On the basis of these observations we speculate that viviparity might occur in vivo with consequent autoinfections; if so, this might explain some puzzling clinical and epidemiological features of haemonchosis, as well as the incomplete efficacy of current control measures.

Abomasum↗
PubMed1985

Thyroid function in epileptic mothers and their infants at birth.

It has been suggested that patients receiving anticonvulsant therapy have depressed thyroid function. Thyroid function was studied in 16 pregnant epileptic women who were receiving various anticonvulsants; 20 nonepileptic pregnant women served as controls. Maternal and umbilical cord blood was collected at delivery and serum thyrotropin, total thyroxine, triiodothyronine, triiodothyronine resin uptake, and free thyroxine levels were measured. The free thyroxine index was calculated from the thyroxine and triiodothyronine resin uptake data. There were no significant differences in any of the maternal parameters. In cord serum, the thyroxine level was significantly lower (p less than 0.001) in the infants of the epileptic mothers. The triiodothyronine resin uptake was slightly increased in the epileptic group (p less than 0.05) so that the free thyroxine index largely compensated for this. The thyrotropin, free thyroxine, and triiodothyronine levels did not differ between the two groups. Thus the low thyroxine values in cord blood of infants of epileptic mothers receiving anticonvulsants probably reflect an alteration in protein binding rather than a true alteration in thyroid function.

Anticonvulsants↗
PubMed1985

Plasma cortisol concentrations in women with menopausal flushes.

A wide variety of stressful stimuli has been shown to increase cortisol secretion. Women with post-menopausal flushes report that their flushes cause acute physical discomfort. We studied the effect of hot flushes on plasma cortisol concentrations in 7 women with frequent post-menopausal flushes. Subjects were monitored subjectively and objectively with a skin temperature recorder over a 3-h period (8:00-11:00 a.m.). The 8:00 a.m. cortisol levels were the highest. These were followed by a decline in plasma levels, suggesting the normal circadian variation in cortisol concentrations. No increase in plasma cortisol levels was found during or after the flush episodes. These results suggest that, in our experimental setting, post-menopausal flushes do not increase cortisol secretion.

Circadian Rhythm↗
PubMed1984

Does sex hormone-binding globulin play a role in the transport of estradiol in vivo?

The distribution of estradiol and testosterone into sex hormone-binding globulin (SHBG)-bound, albumin-bound, and unbound fractions in whole serum under equilibrium conditions at 37 degrees C is described in women with normal menstrual cycles, pregnant women, and newborn infants. The percentage of estradiol bound to SHBG was determined by equilibrium dialysis at 37 degrees C. Whole serum, 0.1 ml, was dialyzed against 0.1 ml of the same serum heated at 60 degrees C for 1 hour (a procedure shown to denature SHBG but not to affect albumin). The percentage of unbound estradiol in whole serum was measured by dialyzing native serum against an isosmotic dextran solution. Testosterone binding was studied similarly. Our findings show that SHBG is an important binder of estradiol in both pregnant and nonpregnant women. However, estradiol binding by SHBG is undetectable in the newborn infant. Testosterone is significantly bound to SHBG under all circumstances. We conclude that SHBG does play a role in the transport of estradiol in women, particularly in pregnancy.

Adult↗
PubMed1984

Investigation of factors influencing 11 beta-hydroxysteroid dehydrogenase (EC 1.1.1.146) activity in midgestational human fetal lung monolayer and explant cultures.

We recently suggested that the 11 beta-hydroxysteroid dehydrogenase (11-HSD) activity in midgestational human fetal lung (HFL) cultures comprised at least two enzymes, one oxidative--associated with epithelial cells, the other reductive--related to fibroblast-like cells. In this study, the effects of various hormones on 11-HSD activity were studied by measuring the interconversion of [3H]cortisol and [14C]cortisone. Human chorionic gonadotrophin, placental medium, and low oxygen concentration increased the conversion of cortisone to cortisol while activity in the reverse direction remained unchanged. No effects were seen when adrenocorticotrophin, prolactin, placental lactogen, estrogens, triiodothyronine or oxytocin were added in physiological amounts.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1983

Human fetal serum cortisol levels at delivery: a review.

A review of the data for fetal cortisol levels at delivery suggests that many of the values published over the past decade are too high owing to the use of methods insufficiently specific for cortisol in cord blood. Pitfalls in the assay of cortisol have been discussed elsewhere (40). The recent use of nonspecific methods is surprising since apparently correct values were established using DIDD in the early 1960s. The high values have mainly been associated with RIA and fluorometry, which have been shown to lack specificity in human urine as well (41). The nature of the interfering material in cord serum and urine is still not entirely clear. At least part of it probably represents cortisol metabolites. The mode of delivery and anesthetic used are also important since values obtained at elective cesarean section are lower than those after vaginal delivery. The lower values at cesarean section may be due to the decreased stress to the infant, the common use of general anesthesia, and/or lower gestational age. Gestational age is very important since values in premature infants are only about half those of mature infants, and are lower in those who go on to develop the respiratory distress syndrome.

Anesthesia↗
PubMed1982

Human fetal serum cortisol levels related to gestational age: evidence of a midgestational fall and a steep late gestational rise, independent of sex or mode of delivery.

Levels of cortisol were determined in umbilical cord serum in the presence and absence of labor at various gestational ages. In the absence of labor, serum cortisol fell (P less than 0.025) from 8.4 ng/ml at 15 to 17 weeks to 4 ng/ml at 17 1/2 to 20 weeks, a change which coincides with a rapid drop in relative adrenal weight. By 35 to 36 weeks, the mean levels had risen to 20 ng/ml and there was a further increase between 37 1/2 and 40 weeks (P less than 0.01) to a mean level of 45.1 ng/ml. Data obtained at vaginal delivery after the spontaneous onset of labor over the period of 26 to 40 weeks were more variable but showed a similar pattern, with levels about twice those in the absence of labor. No differences could be attributed to sex or to the anesthetic used. Thus, there appears to be a rise in the fetal level of cortisol with gestational age in late pregnancy, whether or not labor takes place. This rise is steepest immediately before the normal time of onset of labor and cannot be attributed to the stress associated with labor.

Anesthesia, Obstetrical↗