Pregnanediol-3 alpha-glucuronide measured in diluted urine by mass spectrometry with fast atom bombardment/negative-ion ionization.
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We describe a mass-spectrometric method based on the fast atom bombardment ionization technique in the negative-ion mode for measuring pregnanediol-3 alpha-glucuronide in diluted urine from women. The procedure requires addition of testosterone-17 beta-D-glucuronide (2.5 micrograms/25 microL) to the urine sample as internal standard, and the sample is added directly to the fast atom bombardment target with no further manipulation. We have assessed and evaluated the method by the traditional criteria of reliability. (+info)
The effect of steroids and nucleotidesoon solubilized bilirubin uridine diphosphate-glucuronyltransferase.
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1. It was confirmed that bilirubin glucuronyltransferase can be obtained in solubilized form from rat liver microsomes. 2. Michaelis-Menten kinetics were not followed by the enzyme with bilirubin as substrate when the bilirubin/albumin ratio was varied. High concentrations of bilirubin were inhibitory. 3. The K(m) for UDP-glucuronic acid at the optimum bilirubin concentration was 0.46mm. 4. Low concentrations of Ca(2+) were inhibitory in the absence of Mg(2+) but stimulatory in its presence; the converse applied for EDTA. 5. UDP-N-acetylglucosamine and UDP-glucose enhanced conjugation by untreated, but not by solubilized microsomes. 6. The apparent 9.5-fold increase in activity after solubilization was probably due to the absence of UDP-glucuronic acid pyrophosphatase activity in the solubilized preparation. 7. The activation of solubilized enzyme activity by ATP was considered to be a result of chelation of inhibitory metal ions. 8. The solubilized enzyme activity was inhibited by UMP and UDP. The effect of UMP was not competitive with respect to UDP-glucuronic acid. 9. A number of steroids inhibited the solubilized enzyme activity. The competitive effects of stilboestrol, oestrone sulphate and 3beta-hydroxyandrost-5-en-17-one, with respect to UDP-glucuronic acid, may be explained on an allosteric basis. (+info)
Effect of maternal intrahepatic cholestasis on fetal steroid metabolism.
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Estriol, estriol sulfate, progesterone, and 17 neutral steroid sulfates, including estriol precursors and progesterone metabolites, were determined in 27 cord plasma samples collected after pregnancies complicated by intrahepatic cholestasis of the mother. The levels of these steroids were compared with those in the cord plasma of 42 healthy controls. In the cord plasma, the steroid profile after pregnancies complicated by maternal intrahepatic cholestasis differed greatly from that seen after uncomplicated pregnancy. Two main differences were found. In the disulfate fraction, the concentrations of two pregnanediol isomers, 5alpha-pregnane-3alpha,20alpha-diol and 5beta-pregnane-3alpha,20alpha-diol, were high after cholestasis. Other investigators have shown that, as a result of cholestasis, these pregnanediol sulfates circulate in greatly elevated amounts in the maternal plasma. Our results indicate that in cholestasis these steroids cross the placenta into the fetal compartment, where they circulate in elevated amounts as disulfates. Secondly, the concentrations of several steroid sulfates known to be synthesized by the fetus were significantly lower in the cholestasis group than in the healthy controls. This was especially true of 16alpha-hydroxydehydroepiandrosterone sulfate and 16alpha-hydroxypregnenolone sulfate. These results suggest that, in pregnancies complicated by maternal intrahepatic cholestasis, impairment of fetal steroid synthesis, and especially of 16alpha-hydroxylation, occurs in the fetal compartment.Thus, the changes in maternal steroid metabolism caused by cholestasis are reflected in the steroid profile of the fetoplacental circulation. Furthermore, maternal intrahepatic cholestasis may result in the production of some substance which crosses the placenta and affects fetal steroid metabolism. (+info)
Erythropoietic activity of steroid metabolites in mice.
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The per cent Fe(59) incorporation into circulating erythrocytes as an indicator for new hemoglobin production was used in the polycythemic exhypoxic mouse system to study the effects of certain steroid hormone metabolites on erythropiesis. Enhanced Fe(59) incorporation was observed after the administration of several metabolites with a 5beta-H configuration, while those with a 5alpha-H configuration had no stimulatory effect. The stimulatory effect in avian systems has been shown by others to be due to an increased activity of delta-aminolevulinic acid synthetase, the limiting enzyme in heme biosynthesis. These in vivo studies thus indicate that in this mouse system, as in previously reported studies with avian and human bone marrow cells, some steroid metabolites stimulate hemoglobin synthesis. The observation that the same structure-junction relationship exists in the currently described system as in the avian suggests that these steroids probably induce delta-aminolevulinic acid synthetase in the mouse. The erythropoietic action of these nonandrogenic steroid metabolites may prove to be clinically useful. (+info)
Oral contraceptives and endocrine changes.
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In groups of women taking oral contraceptives and in control groups of women, the serum levels of cortisol, protein-bound iodine, and total thyroxine were measured together with the T(3) binding index. The daily excretion in the urine of free cortisol, 17-hydroxycorticosteroids, 17-ketosteroids, pregnanediol, pregnanetriol, total oestrogens, total catecholamines, and 4-hydroxy-3-methoxymandelic acid was also assayed. The frequency distribution of the values obtained indicates that oral contraceptives have a marked influence on the endocrine environment. The smallest deviations were observed in urinary excretion of total catecholamines and of 4-hydroxy-3-methoxymandelic acid. In some individuals the hormone assays were continued throughout the menstrual cycle. The morning and afternoon levels of serum cortisol tended to increase during the period when the oral contraceptive was being taken. (+info)
Clinical and laboratory findings in a trial of norgestrel, a low-dose progestogen-only contraceptive.
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Norgestrel, a progestogen-only oral contraceptive, was given continually at a dose of 75 mug/day to 144 women of proved fertility. It was an efficient contraceptive with a failure rate of 2.1% (assessed by the "life-table" method) within the first 12 cycles and 3.6% within the first 30 cycles (or 2.0 conceptions per 100 woman-years when assessed by the Pearl index). The overall conception rate for the entire trial period was 2.1% and 1.3 pregnancies per 100 woman-years respectively. Norgestrel caused a high proportion of irregular and generally short bleeding intervals, about one-fifth of the cycles lasting less than 17 days. This irregularity appeared to be due to individual variance in cycle length between women rather than that between their successive cycles. No confirmed instances of thromboembolism were observed. Norgestrel apparently exerts its contraceptive action by several mechanisms: reduction in the sperm penetrability of the cervical mucus and an impairment of luteal function appear important. The serum concentrations of cholesterol and globulin were significantly reduced in women taking norgestrel. Preliminary observations suggest that on discontinuing the medication fertility is promptly restored. Of the 144 women originally enrolled 57 (40%) withdrew for reasons connected with the method before completing 30 months on trial, over half of them because of the irregular menstrual pattern. Nonetheless, in view of its main clinical and laboratory characteristics and simple mode of administration, norgestrel appears to be a useful alternative to the combined type of pill for women unsuitable for, or unable to tolerate, oestrogen-containing preparations. (+info)
Rapid analysis of pregnanediol in pregnancy urine.
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A simple, inexpensive, and rapid method for the determination of pregnanediol in pregnancy urine by gas liquid chromatography is described. Automatic injection of the samples into the gas chromatograph allows up to 36 samples to be run overnight thus saving valuable technical time.The method described can easily be adopted for use in a routine steroid laboratory. The results obtained by this method have been compared with values obtained by the method of Klopper, Michie, and Brown (1955). (+info)
Studies of mammalian glucoside conjugation.
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The mammalian glucoside-conjugation pathway was studied by using p-nitrophenol as the model substrate and mouse liver microsomal preparations as the source of enzyme. The microsomal preparations supplemented with UDP-glucose glucosylated p-nitrophenol; p-nitrophenyl glucoside was identified by chromatography in six solvent systems. The unsolubilized glucosyltransferase of fresh microsomal preparations did not follow the usual Michaelis-Menten kinetics and was easily inhibited by many steroids. All the steroids tested inhibited glucosylation of p-nitrophenol to a greater degree than glucuronidation of p-nitrophenol when assayed in the same microsomal preparations. The steroids inhibited glucosylation with the following decreasing effectiveness: pregnan-3alpha-ol-20beta-one (3alpha-hydroxypregnan-20-beta-one)>oestradiol-17beta 3-methyl ether>oestradiol-17beta>oestriol>pregnane-3alpha,20beta-diol>oestrone. Pregnan-3alpha-ol-20beta-one, pregnane-3alpha,20beta-diol and oestrone had negligible effect on glucuronidation. (+info)