Determination of estradiol metabolites in human liver microsome by high performance liquid chromatography-electrochemistry detector

AIM

To constitute a method to determine the estradiol metabolites in human liver microsome in low concentration of estradiol.

METHODS

Use high performance liquid chromatography after solvent extraction, evaporation, and reconstitution to separate the metabolites and use a electrochemistry detector to detect the metabolites.

RESULTS

With a mobile phase of acetic acid buffer-acetonitrile (50:50, v/v, pH 4.5) at flow rate of 1.0 mL/min and a potential of +0.7 V vs Ag/AgCl, all six composition were well separated and satisfactorily detected. There are E3, 16alpha-OHE1, 2-OHE2, E1, and two unidentified composition. The minimum detectable amount is about 100 p g on column. This method is sensitive enough to detect E1 in a substrate concentration of 1 micromol/L.

CONCLUSION

The method can be used to study the metabolism mechanism of estradiol in liver microsome.

Triple-test screening in in vitro fertilization pregnancies

PURPOSE

To determine whether the results of triple-test analysis differ between spontaneous and IVF pregnancies.

METHODS

The study population consisted of 140 women with singleton pregnancies, 70 by IVF, and 70 by spontaneous conception. The groups were matched for maternal age, gestational week, and laboratory batch. The levels of all triple-test markers--alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG), and unconjugated estriol (u-E3)--were compared between the groups.

RESULTS

Significantly higher HCG levels were detected in the patients with IVF pregnancies than in the control group (1.31 +/- 0.8 vs. 0.95 +/- 0.5 multiple of the medians, respectively, (p < 0.006), but there were no significant differences in AFP or u-E3 levels. Overall, 18.5% of the IVF group were found to be screen-positive as compared with 11.4% of the control group (difference not statistically significant). Only 8 IVF pregnancies (11.4%) reached the lowest calculated risk possible (1:9999) compared with 17 (24.2%) in the control group (p < 0.05).

CONCLUSIONS

Our findings support previous data demonstrating elevated maternal serum HCG in IVF patients in comparison with spontaneous ones.

Changes in rates of salivary estriol increases before parturition at term

OBJECTIVE

The aim of this study was to characterize the increases of salivary estriol concentrations before the onset of labor at term.

STUDY DESIGN

Salivary estriol concentrations were measured in weekly patient-collected samples by means of a sensitive (mean +/- SD threshold, 0.025 +/- 0.001 ng/mL; coefficient of variation, 3.8%) direct enzyme immunoassay in a microtiter plate format. The salivary estriol concentrations in 16 healthy pregnant women were characterized from 30 weeks' gestation until the time of parturition and delivery. Samples were stored frozen at collection and analyzed in batches after delivery.

RESULTS

The median salivary estriol concentration profile revealed a nonlinear rise beginning from 30 weeks' gestation (0.89 ng/mL) until term (2.70 ng/mL, an increase of 201%). At 35 weeks' gestation the salivary estriol concentration median value increased sharply (positive inflection point, 50%-93% increase) at a demarcation between a slower increase during early pregnancy and a more rapid increase during late pregnancy. This positive inflection point associated with a late pregnancy increase characterized subgroups of pregnancies according to the lengths of gestation as follows: early term (delivered at <38 weeks 1 day's gestation), middle term (delivered at 38 weeks 1 day-40 weeks' gestation), and late term (delivered at >40 weeks' gestation). Five weeks before delivery the mean (+/-SEM) rate of rise in salivary estriol concentration was 0.50 +/- 0.13 ng/mL per week to 0.84 +/- 0.26 ng/mL per week in the early term group. The increase in rate for the middle term group was 0.32 +/- 0.06 ng/mL per week to 0.37 +/- 0.26 ng/mL per week, whereas in the late term group the rate of salivary estriol concentration rise was 0.37 +/- 0.03 ng/mL per week to -0.03 +/- 0.25 ng/mL per week.

CONCLUSION

These data demonstrate in normal pregnancies (1) that a direct, nonradiometric measure of salivary estriol concentration can be used to monitor the late pregnancy increase in estriol production, (2) that 35 weeks' gestation marks a positive inflection point of the onset of increased estriol production, and (3) that the late pregnancy rise in salivary estriol concentration shows distinct patterns that tend to be characteristic of the length of pregnancy. These data support the concept that the rate of increase of estriol production is related to the timing of the onset of labor.

Biochemical markers (without markers of infection) of the risk of preterm delivery. Implications for clinical practice

BACKGROUND

New biochemical markers for the risk of spontaneous preterm birth (SPB) give a more precise and earlier diagnosis than the usual ones. We reviewed the data about the principal markers.

RESULTS

Using studies with good methodology and a large number of subjects, we observe that the predictive value of these new markers is somewhat higher than those of the usual markers. Fetal fibro-nectin (FNf) and cervical ultrasound undeniably improve the identification of patients at risk of preterm birth, both in the general population and in these threatened preterm delivery. However no management has yet been demonstrated efficacious, especially in a general population so any recommendations for their systematic utilisation is premature. Other biochemical markers (salivary estriol, serum CRH, etc.) are still under assessment and should not be used outside research protocols.

IMPLICATION FOR PRACTICE

It is appropriate to integrate either FNf or cervical ultrasound into daily clinical practice for patients with signs of preterm labor. These new indicators are of special use when the diagnosis is uncertain with the standard markers (uterine contractions, digital examination). Among these patients, they should reduce the number of hospitalizations and of useless treatments, because of their good negative predictive value. At the same time, for patients poorly 'labeled' by the clinical examination, they should allow the application of intensive management (intravenous tocolysis, corticoids, in utero transfers).

CONCLUSION

Future studies should evaluate these tests in everyday practice. The objective is not to predict preterm birth but to prevent either it or its negative consequences. This goal will be met when we have an effective treatment, without associated adverse effects, to offer patients after a positive test result.

How to diagnose preterm labor: a clinical dilemma

The clinician is faced with many dilemmas in the diagnosis of preterm labor. The tools at hand (no pun intended) yield subjective information and it is difficult to distinguish true labor from false labor. Because preterm labor is multifactorial in cause and can occur in primiparas, estimating risk for the individual patient is difficult. The cause of the preterm labor in the majority of patients is idiopathic; in this group, the use of salivary estriol as a biochemical marker for preterm labor can increase the accuracy of the diagnosis of true labor. It may also lend confidence to the diagnosis of false labor and may allay anxiety and prevent unnecessary interventions. On the horizon are two noninvasive methods: the EMG, to evaluate uterine contractility, and the collascope, to evaluate the cervix. Both show promise and may provide a more objective assessment of risk for preterm delivery among women with symptoms of preterm labor.

Serial salivary estriol to detect an increased risk of preterm birth

OBJECTIVE

To evaluate serial measurements of salivary estriol (E3) to detect increased risk of spontaneous preterm labor and preterm birth.

METHODS

A masked, prospective, multicenter trial of 956 women with singleton pregnancies was completed at eight United States medical centers. Saliva was collected weekly, beginning at the 22nd week of gestation until birth, and tested for unconjugated E3 by enzyme-linked immunosorbent assay. Women were separated into high-risk and low-risk groups using the Creasy scoring system.

RESULTS

A single, positive (at or above 2.1 ng/mL) salivary E3 test predicted an increased risk of spontaneous preterm labor and delivery in the total population (relative risk [RR] 4.0, P <.005), in the low-risk population (RR 4.0, P < or =.05), and in the high-risk population (RR 3.4, P =.05). Two consecutive positive tests significantly increased the RR in all study groups, with a dramatic improvement in test specificity and positive predictive value but only a modest decrease in sensitivity. In women who presented with symptomatic preterm labor, salivary E3 identified 61% of those who delivered within 2 weeks, using a threshold of 1.4 ng/mL.

CONCLUSION

Elevated salivary E3 is associated with increased risk of preterm birth in asymptomatic women and symptomatic women who present for evaluation of preterm labor.

Maternal pregnancy estriol levels in relation to anamnestic and fetal anthropometric data

In epidemiologic studies of perinatal exposures, birth weight has been proposed as a proxy variable for intrauterine estrogen exposure. To assess the validity of this assumption, we performed analyses of the association between estriol levels in 188 women in the 17th, 25th, 33rd, and 37th weeks of pregnancy and the birth weights of their infants. We found a general increase in mean cumulative estriol dose with increasing birth weight category throughout pregnancy. In late pregnancy, mean pregnancy estriol level of mothers of infants in the highest birth weight category (>4,500 gm) was twice as high as that of mothers of infants in the lowest category (<2,500 gm), 775 nmol/liter and 392 nmol/liter, respectively. Smoking lowered the maternal estriol levels by 20% or more throughout pregnancy. With smoking and birth weight included in a regression analysis, maternal age, placental weight, and infant ponderal index did not add any explanatory power to the model. Our data suggest that, on an aggregate level, birth weight can be used as a proxy variable of intrauterine estriol exposure.

Sex steroid hormones in serum and tissue of benign and malignant breast tumor patients

The ability of breast tumors to synthesize sex steroid hormones is well recognized and their local production is thought to play a role in breast cancer development and growth. The aim of this study was to estimate local intra-tumoral and circulating levels of Estrone (E1), Estrone Sulfate (E1S), Estradiol (E2), Estriol (E3), and Testosterone (T) in 33 pre- and postmenopausal women with primary breast cancer in comparison to 12 pre- and postmenopausal women with benign breast tumors. The mean levels of the studied sex hormones were higher in serum and tumor tissue of breast cancer women than those with benign breast tumors apart from Testosterone which showed a significant decrease in pre- and postmenopausal women with breast cancer (P<0.001for follicular phase, P<0.05 for luteal phase, and P<0.005 for postmenopausal). The levels of the five hormones were significantly higher intra-tumoral than in serum of both benign and malignant breast tumor women with E1S as the predominant estrogen. There was only a positive significant correlation between serum and tumor tissue levels of E1 (rs=0.52, P<0.05 for follicular; rs=0.63, P<0.05 for luteal and rs=0.58, P<0.05 for postmenopausal) and a significant correlation between serum and tumor tissue of T (rs=0.64, P<0.05 for follicular; rs=-0.51, P<0.05 for luteal and rs=-0.81, P<0.04 for postmenopausal).

[Biochemical screening in the second trimester of pregnancy from a genetic aspect]

OBJECTIVE

Evaluation of the efficiency of detection of inborn chromosomal aberrations by biochemical screening of pregnant women.

DESIGN

Summary of 9-years study by karyotyping of amniocytes of pregnant women, when pathological levels of AFP, hCG, uE3 were detected. Ethical problems of genetic counselling of pregnant women.

SETTING

Department of Medical Genetics FTN, Chair of Medical Genetics IPVZ, Prague 4.

METHODS

Biochemical screening of pregnant women in II. trimester of pregnancy by Triple Test and computer programme Prenatal Software 1.2.K, cytogenetical examination of amniocytes from amniotic fluid after amniocentesis in II. trimester.

RESULTS

Among 6,471 pregnant women tested by Triple Test 20% had abnormal levels of test. In 1.5% of them an abnormal fetal karyotype was detected. Only 1/3 of them were Down Syndromes, we found also other types of aberrations. During ethically suitable counselling only 2/3 of pregnant women decided to terminate the pregnancy.

CONCLUSION

Biochemical screening of pregnant women in II. trimester is very important help for detection of inborn chromosomal aberrations. The women must be informed by suitable ethical approach.

Predictive value of the triple screening test for the phenotype of Down syndrome

Maternal serum alpha-fetoprotein (MSAFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) are routinely measured in the second trimester ("triple" test) and combined with maternal age to evaluate risk for fetal Down syndrome. Triple test results and clinical findings were retrospectively reviewed for 30 newborns with Down syndrome to determine whether analyte values or second trimester risks for Down syndrome were more extreme in affected pregnancies where cardiac or other severe congenital malformations were present compared to those cases where major anatomical abnormalities were absent. Mean MS-AFP, uE3, maternal age, and second trimester Down syndrome risk were all similar in the two groups of pregnancies. However, hCG concentrations did appear to be higher in the group of Down syndrome pregnancies with anatomical anomalies (mean 1.74 MoM versus 1.19 MoM) (P<0.05). Overall, there was no significant difference in the incidence of major anomalies in patients with screen-positive test results versus those cases that were not identified by the triple test. Prenatal counseling should therefore reflect the general expectations of the Down syndrome phenotype that have been established from live-born infants with this disorder.

Incremental cost-effectiveness analysis: the optimal strategy depends on the strategy set

Evaluating the incremental cost-effectiveness of a technology is critical to understanding the impact of its adoption. The purpose of this study was to evaluate, using a particular example, how the specific alternatives selected for a cost-effectiveness analysis may influence the results of the analysis. In this example, we analyzed the incremental cost-effectiveness of estriol screening for Down syndrome. Model assumptions of expected costs and effectiveness were based on previously published work involving four clinical strategies, including a "do nothing" (no screening) strategy. When the analysis started with all four strategies, two of the strategies could not be considered cost-effective because of extended dominance. However, when we eliminated the "do nothing" from the strategy set because of its clinical irrelevance, all three remaining strategies might be considered cost-effective from a policy perspective. We concluded that the incremental cost-effectiveness of clinical strategies could be strongly affected by the starting point for the analysis.

Biochemical markers for preterm labor and birth: what is their role in the care of pregnant women?

Two biochemical tests, one for oncofetal fibronectin (fFN) and the other for estriol found in maternal saliva (SalEst) have been developed to improve the ability to predict preterm labor and birth. Fetal fibronectin is a protein secreted by the trophoblast and not normally present in vaginal and cervical secretions late in pregnancy. The presence of fFN between 22 and 37 weeks gestation may be a marker for preterm labor. Salivary estriol is a form of estrogen produced in the placenta from fetal precursors. Normally, estriol rises during pregnancy--the rise being accelerated 3 to 5 weeks prior to both term and preterm births. Both tests have high negative predictive values. This may serve to prevent unnecessary treatment of women with uterine contractions who are not truly in preterm labor. The fFN specimen is collected during vaginal examination. Sexual intercourse or vaginal examination within the prior 24 hours, vaginal bleeding, and uterine contractions may lead to a false positive test. Salivary estriol may be collected by the woman in her own home; however, specific instructions about eating, drinking, smoking, and the timing of saliva collection must be followed. Further study of both tests is required to determine their potential for reducing rates of preterm birth.

[Determination of sexual hormones in cosmetics by using Re-HPLC method]

A Re-HPLC method for the determination of seven kinds of sexual hormones, such as estriol in cosmetics was established. Zorbax C18 and Methanol-water were used as solid phase and liquid phase respectively. Methanol was used to extract the hormones in samples using a ultrasonic method. In the background with cosmetic samples, the relative standard deviations of those seven kinds of added sexual hormones were 1.2%-4.4% at low concentration and 2.1%-5.8% at high concentration. The recoveries rates of those hormones were 87.7%-103.1% and 86.6%-104.4%, respectively.

[Clinical use of a quadruple biochemical marker in the prediction of obstetric complications]

The objective was to evaluate the association of an abnormal second trimester prenatal biochemical screening with the subsecuent development of pregnancy complications in women carrying chromosomally normal fetuses. A prospective study of 123 pregnant patients was performed. Specimens were assayed for alpha-fetoprotein, unconjugated estriol, free alpha hCG, and total hCG. The study included the evaluation of the mean and standard desviation as well as multiple of the median. Six women (4.6%) had positive results. The frequency of pregnancy complications in this group was 33.3%, while in the group with negative screening was 11.1%. As conclusion, positive four marker screening is associated with a adverse pregnancy evolution. However the usefulness of four marker screening for to predict pregnancy complications needs more investigations.

Endocrine assays to predict preterm delivery

Advances in the understanding of the endocrine and hormonal mechanisms involved in normal and abnormal labor have led to clinical research into the roles of hormones and cytokines in preterm labor. This article reviews the current status of assays for estriol, activin, corticotropin-releasing hormone, interleukin-6, and relaxin as predictors of preterm labor and delivery.

Determination of 17 beta-estradiol and its metabolites in sewage effluent by solid-phase extraction and gas chromatography/mass spectrometry

The paper describes a simple and quantitative method for monitoring non-conjugated 17 beta-estradiol (E2) and its metabolites estrone (E1) and estriol (E3) as environmental contaminants in municipal sewage effluents. Estrogens were preconcentrated and cleaned up by solid-phase extraction using a reversed-phase C18 cartridge. They were derivatized with pentafluoropropionic acid anhydride, and the products were analyzed by gas chromatography/mass spectrometry. Recoveries from spiked distilled water and sewage were better than 87% at fortification levels of 100 and 20 ng/L. For a 1 L sewage sample and a concentration factor of 5000, detection limits were 5 ng/L for E1 and E2 and 10 ng/L for E3. In a brief survey of Canadian wastewater, these estrogens were detected in many raw sewage and effluent samples at concentrations ranging from 6 to 109 ng/L for E1, from < 5 to 15 ng/L for E2, and from < 10 to 250 ng/L for E3.

HPLC-fluorescence determination of unconjugated estrogens in pharmaceuticals

A fluorimetric liquid chromatographic method (lambda(ex) = 280 nm; lambda(em) = 312 nm) was developed for measurements of unconjugated estrogens (estradiol and estriol) in pharmaceutical dosage forms using a reversed-phase column with water acetonitrile at different composition as mobile phase. The in vitro release profiles of three different estradiol transdermal therapeutic systems were determined through a medical-grade silicone rubber subdermal implant material membrane, using a modified Franz diffusion apparatus at 37 degrees C in presence of PEG 400. The HPLC method possesses advantages of rapidity, simplicity and accuracy.

Biochemical markers of trisomy 21 in amniotic fluid

In a study of amniotic fluid from 91 Down's syndrome cases and 240 controls, we have shown that the median values of four biochemical markers (AFP, total hCG, free beta hCG, and unconjugated oestriol) in the amniotic fluid of pregnancies affected by Down's syndrome on the whole reflect those observed in the maternal serum of affected cases. The median MOM for AFP was lower than average (0.56), as was that for unconjugated oestriol (0.55), whilst those for total hCG (1.82) and free beta hCG (2.10) were increased on average. The width of the distribution of marker levels in amniotic fluid is similar to that in serum for free beta hCG and total hCG but between 1.5 and 2 times wider for unconjugated oestriol and AFP. Analysis of data by fetal sex showed a significantly higher median MOM in female control cases compared with male controls for the analytes free beta hCG, total hCG, and unconjugated oestriol, but not for AFP. Amongst the Down's syndrome cases, this trend was not statistically significant and we cannot confirm a previous study which reported that elevated levels of amniotic fluid total and free beta hCG were associated only with female fetuses.

Nomograms to help inform women considering Down's syndrome screening

OBJECTIVE

To derive graphical information for use in counselling women considering whether or not to have maternal serum screening for Down's syndrome.

DESIGN

Statistical modelling of the frequency distribution of estimated Down's syndrome risk for four marker combinations.

RESULTS

Nomograms are provided showing for each maternal age: (a) the detection and false-positive rates, and (b) the proportion of pregnancies with different estimated risks.

CONCLUSION

When screening is offered, clinicians need to have information readily available on test accuracy and the likely result, which is specific to the individual.

Shared reaction in solid-phase immunoassay for estriol determination

In the search of factors responsible for the experimental difficulties in developing accurate and sensitive solid-phase immunoassay of steroids, an experimental model has been set up for the study of nonspecific interaction of the steroid analyte with the coating protein. Along with the development of a highly sensitive enzyme-linked, solid-phase immunoassay for estriol measurement, we observed evidence of shared reactions. This property, to our knowledge not previously described for monomeric, low-molecular-weight antigens like estrogens, has been attributed to the presence of bovine serum albumin, which is capable of binding estrogens through hydrophobic interactions. The addition of estriol in solution in large excess did not reach a complete inhibition of the binding, so the possibility was excluded that the antibody simply binds to the adsorbed estrogen. The simplest explanation for the occurrence of the reaction is the hypothesis that a family of antigen determinants arises when the estriol is conjugated to a protein carrier. The corresponding antibodies are revealed only when the estrogen participates to the actual analytical system in the form of a steroid-protein conjugate. In the experiment, the estriol has been recognized as being coupled with one or more amino acid side chains present around its site of covalent linkage to the immunogen protein. The discussed results may be of help in developing a solid-phase immunoassay of small antigens as steroids, but also in applying the hybridoma and phage display technologies, the screening methods of which are based on sensitized solid phases.

Why so much oestriol? A comparison of the aromatisation of androstenedione and 16 alpha-hydroxyandrostenedione when incubated alone or together with human placental microsomes

Estimates of the relative abundance of 16 alpha-hydroxy- and 16-deoxyoestrogens in late pregnancy urine lie between 13:1 and 5:1, yet the ratio of the concentrations of the major precursors 16 alpha-hydroxydehydroepiandrosterone sulphate and dehydroepiandrosterone sulphate in cord blood is about 2.5:1. This discrepancy might imply that 16 alpha-hydroxy-C19 steroids are used more efficiently for placental oestrogen biosynthesis than are the 16 alpha-deoxy-C19 steroids. On testing this hypothesis by incubation of placental microsomes with 16 alpha-hydroxy- and 16-deoxy- precursors together (concentration ratios 128:1 to 1:1), initial rates of oestrogen formation were highest from the 16-deoxy-C19 steroid. Additionally, whilst each substrate appeared to inhibit the aromatisation of the other, the 16-deoxy-C19 steroid was the more potent inhibitor. These findings were supported by an analogous experiment with placental slices. When each precursor was examined separately with microsomes from 4 placentae, aromatisation of the 16 alpha-hydroxy-C19 steroid (Michaelis constant, (Km) 0.75-1.24 mumol/l, maximum reaction velocity (Vmax) 28-69 pmol product/min/mg protein) was less efficient than that of the 16-deoxy-C19 steroid (Km 0.10-0.15 mumol/l, Vmax 71-145 pmol product/min/mg protein). To reconcile the disparity between the measured utilisation of precursors in vitro and expectations drawn from precursor availability and urinary excretion rates, sources of urinary 16 alpha-hydroxyoestrogens additional to placental aromatisation need to be considered. Hydroxylation of 16-deoxyoestrogens (the phenolic pathway) appears limited but aromatisation in fetal liver of 16 alpha-hydroxyandrostenedione not utilised by the placenta appears to be worth attention.