Plasma Estrone Research Articles

Development of a rapid, sensitive and authentic LCMS method for the determination of Dexamethasone, Testosterone and Estrone (E1) in human plasma

A simple, rapid, fast, precise and accurate reverse-phase HPLC method was developed and validated for the simultaneous determination of Dexamethasone, Testosterone and Estrone (E1) in pre-mixture by using RP-HPLC having photon diode array detector, Evaporative Light Scattering Detector (ELSD) and coupled with dual electrospray ionization mass spectrometry Quadrupole time-of-flight (LCMS). The method has shown adequate separation for Dexamethasone, Testosterone and Estrone (E1). Separation was achieved on reverse phase Shodex C18, 3 μm, 4.6 × 100 mm, using isocratic elution mode with a mobile phase Acetonitrile and 0.1% formic acid in water. The flow rate was 1 mL/min and effluents were monitored at 240 and 280 nm, using photodiode array (PDA) detector, ELSD and Ion detection was performed by dual electrospray ionization source (dual ESI) in positive mode. The recovery of steroids was found to be in the range of 98–102%. The described method was linear. The precision, ruggedness and robustness values were also within the prescribed limits.

Plasma estrone sulfate concentrations and genetic variation at the CYP19A1 locus in postmenopausal women with early breast cancer treated with letrozole

Estrogen synthesis suppression induced by aromatase inhibitors in breast cancer (BC) patients may be affected by single nucleotide polymorphisms (SNPs) of the gene encoding aromatase enzyme, CYP19A1. We assessed the association between plasma estrone sulfate (ES), letrozole treatment, and four SNPs of CYP19A1 gene (rs10046 C>T, rs4646 G>T, rs749292 C>T, rs727479 T>G) which seem to be related to circulating estrogen levels. Patients were enrolled into a prospective, Italian multi-center clinical trial (Gruppo Italiano Mammella, GIM-5) testing the association of CYP19A1 SNPs with the efficacy of letrozole adjuvant therapy, in postmenopausal early BC patients. SNPs were identified from peripheral blood cell DNA. Plasma ES concentrations were evaluated by Radio Immuno Assay. Blood samples were obtained immediately before letrozole therapy (N = 204), at 6-weeks (N = 178), 6 (N = 152) and 12-months (N = 136) during treatment. Medians (IQR) of ES were 160 pg/mL (85–274) at baseline, 35 pg/mL (12–64) at 6-weeks, 29 pg/mL (17–48) at 6 months and 25 pg/mL (8–46) after 12 months treatment. No statistically significant association was evident between polymorphisms and ES circulating levels during letrozole therapy. Letrozole suppression of the aromatase enzyme function is not affected by polymorphisms of CYP19A1 gene in postmenopausal BC patients.

Effect of CYP19 rs6493497 and rs7176005 haplotype status on in vivo aromatase transcription, plasma and tissue estrogen levels in postmenopausal women

High plasma levels of estradiol (E 2) are correlated to increased breast cancer risk in postmenopausal women. Recently, a study reported two single nucleotide polymorphisms (SNPs) (rs6493497; C → T and rs7176005; G → A) in the aromatase ( CYP19) promoter 1.1 to be associated with elevated plasma E 2 levels, most likely due to enhanced transcription. In silico predictions suggested increased transcription factor binding for the rs7176005_A allele. We genotyped 46 breast cancer patients for rs6493497 and rs7176005 status and assessed the potential association between CYP19 SNP status and (i) CYP19 mRNA levels in tumour and normal breast tissue, and (ii) estrogen levels in plasma, tumour and normal breast tissue. In addition, we measured CYP19 SNP status and correlated it to plasma estrogen levels in a confirmatory dataset of 108 healthy postmenopausal women. We found no correlation between either of the two SNPs and CYP19 mRNA level. In the breast cancer patients, the rs6493497_T/rs7176005_A variant haplotype was associated with low plasma estrone (E 1) ( p = 0.038) and low E 2 ( p = 0.050) levels; however, no correlation was recorded between SNP status and plasma estrogen levels in the cohort of 108 healthy postmenopausal women. Our findings indicate rs6493497 and rs7176005 status not to enhance CYP19 transcription or increase estrogen levels in postmenopausal women.

Tissue bioaccumulation patterns, xenobiotic biotransformation and steroid hormone levels in Atlantic salmon ( Salmo salar) fed a diet containing perfluoroactane sulfonic or perfluorooctane carboxylic acids

In the present study, groups of juvenile Atlantic salmon ( Salmo salar) were fed gelatine capsules containing fish-food spiked with PFOA or PFOS (0.2 mg kg −1 fish) and solvent (methanol). The capsules were given at days 0, 3 and 6. Blood, liver and whole kidney samples were collected prior to exposure (no solvent control), and at days 2, 5, 8 and 14 after exposure (Note: that day 14 after exposure is equal to 7 d recovery period). We report on the differences in the tissue bioaccumulation patterns of PFOS and PFOA, in addition to tissue and compound differences in modulation pattern of biotransformation enzyme genes. We observed that the level of PFOS and PFOA increased in the blood, liver and kidney during the exposure period. Different PFOS and PFOA bioaccumulation patterns were observed in the kidney and liver during exposure- and after the recovery periods. Particularly, after the recovery period, PFOA levels in the kidney and liver tissues were almost at the control level. On the contrary, PFOS maintained an increase with tissue-specific differences, showing a higher bioaccumulation potential (also in the blood), compared with PFOA. While PFOS and PFOA produced an apparent time-dependent increase in kidney CYP3A, CYP1A1 and GST expression, similar effects were only temporary in the liver, significantly increasing at sampling day 2. PFOA and PFOS exposure resulted in significant decreases in plasma estrone, testosterone and cortisol levels at sampling day 2, and their effects differed with 17α-methyltestostrerone showing significant decrease by PFOA (also for cholesterol) and increase by PFOS. PFOA significantly increased estrone and testosterone, and no effects were observed for cortisol, 17α-methyltestosterone and cholesterol at sampling day 5. Overall, the changes in plasma steroid hormone levels parallel changes in CYP3A mRNA levels. Given that there are no known studies that have demonstrated such tissue differences in bioaccumulation patterns with associated differences in toxicological responses in any fish species or lower vertebrate, the present findings provide some potential insights and basis for a better understanding of the possible mechanisms of PFCs toxicity that need to be studied in more detail.

Circulating steroid hormones in prostate carcinogenesis. Part 2: Estrogens.

The aim of this review is to describe the associations between circulating plasma estrogens and prostate cancer (PCa). We recall the origins of estrogens, which derive from the aromatization of androgens, but also by sulfatase hydrolysis of estrone sulfate (E1-S), the main circulating plasma estrogen. We evoke that the carcinogenic effects of estrogens were demonstrated in the rat and murine prostate when estrogens and androgens were simultaneously administered to them. We also describe estrogen proliferative activity and the genotoxicity of estrogen-hydroxylated metabolites with the formation of DNA adducts. We report published aromatase and CYP1B1 polymorphisms found in men with PCa. We published a bibliography on the relation between PCa and prostate inflammation, as well as the possible role of obesity in the aggressiveness of PCa. In this review, we provide an exhaustive list of assays carried out in subjects at high risk for PCa compared with Caucasians, showing that higher estrogen levels were found in the plasma of these subjects at high risk for PCa. Plasma estrone was the estrogen for which plasma concentration was highest in subjects of African descent. We recall the links observed between plasma estrogens, particularly E1-S, and PCa aggressiveness. Finally, we describe assays for determining hydroxylated estrogens and DNA adducts in the urine of men with PCa. We insist on the importance of the technology employed in estrogen measurement and propose the use of mass spectrometry methods to carry out estrogen assays, in order to decrease variability in the results of plasma estrogen assays.

36 CHANGES IN PLASMA CONCENTRATIONS OF PROGESTERONE AND ESTROGENS DURING GESTATION IN COWS WITH STILLBORN SOMATIC CELL CLONED CALVES

Cloning of mammals by nuclear transfer frequently results in gestational or neonatal failure with a variety of abnormalities that are likely caused by inappropriate epigenetic reprogramming. Early diagnosis of fetal abnormality is important for efficient production of cloned animals. Sex steroids are produced in the bovine placenta and their levels in the blood might be useful as a measure of fetal well being, as they are in humans. The objective of this study was to investigate whether changes in peripheral concentrations of progesterone and estrogens reflect fetal conditions. Donor cells for nuclear transfer were obtained from subculture of cumulus cells retrieved from ovarian follicles of a Japanese Black cow. Recipient oocytes were derived from ovaries obtained at an abattoir and matured in vitro. Metaphase II oocytes were enucleated and each fused with a donor cell by DC pulses. Nuclear transferred oocytes were activated and cultured for 7 days. Embryos developed to the blastocyst stage were transferred into the uterine horn ipsilateral to the ovary bearing the CL of 29 multiparous Japanese Black and Holstein crossbred cows at 7 to 8 days after the day of standing oestrus (Day 0). Blood was collected at regular intervals from Day 40 until parturition. Plasma progesterone, estrone, oestradiol-17β, and estrone sulfate were measured by RIA in 4 recipient cows. 2 vaginally delivered healthy calves weighed 35 and 36 kg on days 278 and 280, respectively. The other 2 delivered stillborn calves weighed 42 and 31 kg by Caesarean section on days 267 and 287, respectively. Steroid profiles were compared with each other and with those in a cow made pregnant by embryo transfer. Statistical differences at stages of gestation were analysed with repeated-measures ANOVA. Stillborn calves were subjected to necropsy and histopathological analysis. Significant differences in steroid levels were observed individually and temporarily. In the cow bearing the former stillborn, progesterone and oestradiol-17β concentrations tended to be lower during mid and late gestation, respectively. Large offspring syndrome, ventricular septal defect, pulmonary oedema, hepatic fibrosis, and placental dysplasia were found in the calf by necropsy and histopathological analysis. In the cow bearing the second stillborn, plasma progesterone concentrations were temporarily increased from days 220 to 230 and reached a peak of 16 ng mL–1, which was approximately 3 times as high as before (5.0 ± 0.9; mean ± s.d.), then followed by a similar transient increase in estrogens during days 240 and 250 (170 pg mL–1, 16 pg mL–1, and 21 ng mL–1 at peak of estrone, oestradiol-17β, and estrone sulfate, respectively). Thereafter, oestrogen concentrations stayed low until parturition. As internal organs of the stillborn calf were severely autolysed with polyhydramnios at birth, the fetus might have been dead around Day 250. These results imply that changes in peripheral steroid concentrations in some cases reflect fetal condition.

Plasma estrogen concentrations after oral and vaginal estrogen administration in women with atrophic vaginitis

In this open-label, randomized, multiple-dose, two-treatment crossover study, 24 postmenopausal women with moderate to severe atrophic vaginitis received 0.3 mg conjugated estrogens daily for 14 days: 7 days orally (0.3 mg tablet) and 7 days vaginally (0.5 g cream). Steady-state plasma concentrations of E2 and estrone were one-third lower after vaginal versus oral administration of conjugated estrogens.

Plasma estrone sulfate assay in men: Comparison of radioimmunoassay, mass spectrometry coupled to gas chromatography (GC–MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Background Estrogens are involved in the natural history of the prostate cancer and estrone sulfate, the quantitatively main circulating plasma estrogen in men, has been associated with an aggressive form of this cancer. A convenient and accurate plasma assay of this steroid has become important. Methods We simultaneously assayed estrone sulfate in the plasma of one hundred men aged 30–50 years, according to LC-MS/MS, GC–MS after solvolysis of E 1S, radioimmunoassay after a chromatographic purification step, and a direct RIA commercial kit. Results Estrone sulfate plasma levels obtained with the first three methods were not significantly different. However, estrone sulfate levels measured by the direct RIA were three-fold higher than those obtained by the first three methods. We showed that the excessively high estrone sulfate levels obtained with the direct RIA kit had two origins: interference by high dehydroepiandrosterone sulfate plasma levels in men, and estrone sulfate inaccurate low concentrations in the standards. Conclusion The LC-MS/MS method can be considered as an optimum option for clinical laboratory. The GC–MS method requires solvolysis to estrone, but allows simultaneous unconjugated steroid measurement. RIA method, with chromatographic purification, is cumbersome, but less expensive. DSL-5400 kit yielded estrone sulfate plasma levels that were too high.

Identification of cryptorchidism in horses by analysing urine samples with gas chromatography/mass spectrometry

Currently there are two common radioimmunoassay-based methods for the detection of equine cryptorchidism; one measures testosterone concentrations in peripheral blood samples taken before and after an intravenous injection of human chorionic gonadotrophin (hCG) and the other measures plasma estrone sulfate. However, each of these invasive methods has its own shortfalls and neither gives unequivocal results. In this article a highly reliable gas chromatography/mass spectrometry (GC/MS) method is described based on the analysis of urine samples for the identification of cryptorchidism in horses, some as young as 2 years old.

Maternal plasma oestrone sulphate concentration prior to parturition in relation to birth weight of the calf in primiparous, 2-year-old, Angus heifers

Dystocia and assisted calving in primiparous heifers are persistent problems in beef herds, and incidence increases with increasing birth weight of calves. Plasma samples taken from 33 primiparous, 2-year-old, Angus heifers 2 days prior to parturition were analysed for oestrone sulphate concentration. Additional samples taken at 4, 6, 8 and 10 days prior to parturition were analysed for 17 of these heifers. At parturition, birth weight of the calf, post-partum live weight of the heifer, assistance at calving ( n = 6) and status of the calf (stillborn ( n = 4) vs. alive) were recorded. Maternal plasma oestrone sulphate concentration was stable from 10 to 4 days prior to parturition and increased between 4 and 2 days prior to parturition for non-assisted heifers. Maternal plasma oestrone sulphate concentration did not affect the probability of assistance at calving or stillbirth.

Metabolic and Hormonal Effects of Oral DHEA in Premenopausal Women with HIV Infection: A Randomized, Prospective, Placebo-controlled Pilot Study

Women with HIV infection use dehydroepiandrosterone (DHEA) because of its potential effects on mood and energy. We examined the effects of DHEA on the hypothalamic-pituitary-adrenal and gonadal axes and on insulin sensitivity. Fifteen HIV-positive women were randomized to receive placebo (6 subjects) or oral DHEA (9 subjects). ACTH-, CRF-, and GnRH-stimulation tests were performed before and after 8 weeks of treatment. DHEA, DHEA-S, dihydrotestosterone, total testosterone, free testosterone, sex hormone-binding globulin, estrone, estradiol, cortisol, insulin, IGF-1, IGFBP-1, IGFBP-3, and adiponectin in plasma or serum were measured. There was a significant increase in DHEA (p<0.004), DHEA-S (p<0.008), total testosterone (p<0.008), dihydrotestosterone (p<0.004), androstenedione (p<0.04), and estrone (p<0.03) from baseline within the DHEA group but not within the placebo group. There was a significant increase in DHEA (p<0.0006), DHEA-S (p<0.032), total testosterone (p<0.01), and dihydrotestosterone (p<0.005) in the DHEA group compared with the placebo group. Oral DHEA produces significant increases in circulating DHEA, DHEA-S, testosterone, DHT, and, possibly, androstenedione and estrone levels in premenopausal women with HIV infection. In the current pilot study these hormone changes did not affect the pituitary or adrenal axis or insulin/IGF indices. Long-term studies with larger groups of patients are needed to confirm these data and to determine their clinical significance.

Fat/fiber intakes and sex hormones in healthy premenopausal women in USA

The mechanisms by which diet affects breast cancer (BC) risk are poorly understood but a positive relationship between fat and a negative association with fiber intake and BC risk have been demonstrated. Here we study the association between dietary fat/fiber ratio and estrogen metabolism. Fifty women were recruited, 22 were included in the low fat/high fiber and 22 were in the high fat/low fiber group and 6 did not meet our criteria. Estrogens (determined in plasma, urine and feces) and dietary records were collected during 3 following days. All data were collected in winter and in summer. The high fat/low fiber group had significantly higher urinary total estrogens, estriol-3-glucuronide, 2-hydroxyestradiol, 16α-hydroxyestrone, and a higher 2-hydroxyestrone/4-hydroxyestrone ratio. Total fat intake correlated significantly with plasma estrone, estradiol, urinary 2-hydroxyestrone, 2-hydroxyestradiol, 2-hydroxyestrone/4-hydroxyestrone ratio, and total urinary estrogens, even after adjustment for total fiber intake. The high fat/low fiber diet was associated with high values both for catechol and 16α-hydroxylated estrogens and a high 2-hydroxyestrone/4-hydroxyestrone ratio, but 2-hydroxyestrone/16α-hydroxyestrone ratio was not different between the groups. Our results suggest that fat affects estrogen metabolism more than does fiber and that one mechanism resulting in high estrogen values is an increased reabsorption of biliary estrogens.

Excess estrogen sulfoconjugation as the possible cause for a poor sign of parturition in pregnant cows carrying somatic cell clone fetuses

We conducted this study to elucidate a factor causing a poor sign of parturition and prolonged gestation, which is frequently observed in cows carrying somatic clone fetuses. Pre-partum rises in concentrations of plasma estrone and estradiol-17beta in the recipient cows pregnant with clones were subtle. By contrast, the plasma concentration of estrone sulfate in clone pregnancies increased gradually from pre-initiation of parturition induction whereas control cows that received in vivo-derived embryos showed a significant increase at parturition. Therefore, in clone pregnancies, the ratio of estrone/estrone sulfate was low during the pre-partum period compared with control. Messenger RNA expression of estrogen sulfotransferase (SULT1E1) in the placenta at parturition was significantly higher in clone pregnancies than control pregnancies and was localized in binucleate cells (BNC). SULT1E1 mRNA abundance was negatively and positively correlated with concentrations of maternal estrone and estrone sulfate at parturition respectively. Messenger RNA expressions of estrogen sulfatase (STS) and aromatase (CYP19) were similar between clone and control pregnancies and were localized in BNC and caruncular epithelial cells. STS and CYP19 mRNA abundances showed positive correlations with maternal estradiol-17beta concentration. The population of BNC in the placenta did not differ between clone and control pregnancies. Plasma cortisol concentration of vaginally delivered newborn clone calves was comparable with those of control, although cesarean section delivered clone calves showed a low concentration. These results suggest that excess estrogen sulfoconjugation is the reason for the perturbed low ratio of active to inactive estrogens and the resulting hormonal imbalance contributes to the lack of overt signs of readiness for parturition in cows pregnant with clones.

Plasma testosterone and estrone sulfate concentrations in relation to age in Thoroughbred stallions

Plasma testosterone and estrone sulfate concentrations in relation to age in Thoroughbred stallions

An optimised, highly sensitive radioimmunoassay for the simultaneous measurement of estrone, estradiol and estrone sulfate in the ultra-low range in human plasma samples

Following the introduction of potent aromatase inhibitors for the treatment of breast cancer patients, highly sensitive methods have become mandatory to evaluate the influence of these drugs on plasma estrogen levels. Commercially available kits for estrogen measurements are not suitable for these kinds of evaluations due to their detection limits that are close to baseline estrogen levels in postmenopausal women. We describe here an optimised radioimmunoassay suitable for the simultaneous measurement of plasma estrone (E 1), estradiol (E 2) and estrone sulfate (E 1S) levels in the ultra-low range. Following incubation with [ 3H]-labelled estrogens as internal standards, crude estrogen fractions were separated by ether extraction. The E 1S fraction was hydrolysed with sulfatase followed by eluation on a Sephadex column. Free estrogens (E 1, E 2) were separated by chromatography (LH-20). Estrone and E 1S (following hydrolysis) were converted into E 2, and each estrogen fraction was measured by the same highly sensitive and specific radioimmunoassay using estradiol-6-(O-carboxymethyl)-oximino-2-(2-[ 125I]-iodo-histamine) as ligand. Although several purification steps were involved, the internal recovery values for tritiated estrogens were found to be 88%, 90%, and 49% for E 1, E 2 and E 1S, respectively. The intra-assay coefficient of variation was <5% for all recovery measurements. The detection limits were calculated following repeated blank measurements and found to be 1.14 pmol/L for E 1, 0.67 pmol/L for E 2, and 0.55 pmol/L for E 1S, respectively. The intra-assay coefficient of variation (CV) was found to be 3.4% for E 1, 5.1% for E 2 and 6.1% for E 1S, while the inter-assay CV was 13.6%, 7.6% and 7.5% for E 1, E 2, and E 1S, respectively. Considering normal plasma levels for E 2 (15 pmol/L), E 1 (80 pmol/L) and E 1S (400 pmol/L) in postmenopausal women, the method allows theoretically to detect suppression of plasma E 2, E 1 and E 1S levels by 95.5%, 98.6% and 99.9% when starting from average, normal postmenopausal levels. Thus, the method presented here is to our knowledge the currently most sensitive assay available for plasma estrogen measurements in the ultra-low range and, as such, a reliable tool for a proper evaluation of potent aromatase inhibitors and other potential drugs influencing on plasma estrogen levels.

Relationship of prepartum plasma concentrations of estrone sulfate and estradiol‐17β with the weight of the calf and placental parameters in Holstein–Friesian cows

ABSTRACTThe aim was to evaluate the relationship of prepartum plasma estrone sulfate (E1S) and estradiol‐17β (E2β) concentrations with the weight of the calf and the placental parameters. Holstein–Friesian cows (n = 33) inseminated artificially with Japanese Black beef bull semen at Hiroshima University Farm in Japan were used for the experiment. Blood samples were taken every day from day 270 of gestation until the day after calving. The plasma samples were analyzed for E1S and E2β by enzyme immunoassay. The calf birth weight was taken immediately after calving. Complete fetal membranes were collected from 19 cattle and the weights of the placental components and the number of cotyledons were recorded. All 33 cattle delivered singleton normal calves. The prepartum plasma E1S concentration was found to correlate significantly (P &lt; 0.01) with the calf birth weight (r = 0.83), total fetal membrane weight (r = 0.81), cotyledonary weight (r = 0.79) and inter‐cotyledonary membrane weight (r = 0.64), but it did not correlate significantly with the number of cotyledons, whereas prepartum plasma E2β was not found to correlate significantly with the weight of either the calf or any of the placental components except the number of cotyledons. In conclusion, prepartum plasma E1S, not plasma E2β, was found to correlate significantly with the weight of the calf and the placental components.

Endogenous sex hormones, prolactin and mammographic density in postmenopausal Norwegian women

The associations between endogenous sex hormone levels and breast cancer risk in postmenopausal women are well established. Mammographic density is a strong risk factor for breast cancer, and possibly an intermediate marker. However, the results from studies on the associations between endogenous sex hormones and mammographic density are conflicting. The authors examined the associations between circulating levels of sex hormones, sex hormone binding globulin (SHBG) and prolactin and mammographic densities among postmenopausal women not currently using postmenopausal hormone therapy (HT). The authors also examined if insulin-like growth factor-I (IGF-I) levels influenced the association between estrogen and mammographic density. Altogether, 722 postmenopausal participants in the Norwegian governmental mammographic screening program had endogenous hormone concentrations measured. Mammograms were classified according to percent and absolute mammographic density using a previously validated computer-assisted method. After adjustment for age, number of children, age at menopause, body mass index and HT use, both plasma concentrations of SHBG (p-trend = 0.003) and estrone (p-trend = 0.07) were positively associated with percent mammographic density. When the analyses were stratified according to median IGF-I concentration, the weak association between estrone and mammographic density was strengthened among women with IGF-I levels below median, while the association disappeared among women with over median IGF-I levels (p for interaction = 0.02). In summary, the authors found a positive association between plasma SHBG levels and mammographic densities among 722 postmenopausal Norwegian women not currently using HT. Further, the authors found a positive but weak association between plasma estrone concentration and mammographic density, which appeared to be modified by IGF-I levels.

Buserelin acetate microparticle dispersion effects drug release and plasma E 1 levels

We investigated the effect of different dispersion methods on release behavior and efficacy onset following microparticle administration of buserelin acetate (BA) sustained-release injection. In this in vitro release study, the initial dispersion of BA increased with increased stirring speed ( p < 0.01). Stability of BA was studied over 7 days after BA release. The initial BA release rate was higher ( p < 0.01) after a 1-min vibration dispersion method (VDM) using a test tube mixer (2000 rpm) compared with the standard dispersion method (SDM) by hand. Without shaking, powder aggregation was observed, and BA release was lower than in either the SDM or VDM methods. In this study using 4-week-old Sprague–Dawley female rats, the initial plasma estrone (E 1) concentrations were lower ( p < 0.05) in the VDM method than in the SDM method. Observations by optical microscope and scanning microscope showed no change in microparticle shape or distribution of size induced by SDM, VDM or the ultrasonication dispersion method. These results suggest that different dispersion methods do not change the shape and distribution of microparticle size, but clearly change the BA release rate and the transition in plasma E 1 concentrations that can affect drug efficacy.

Fatty acid esterification of lipoprotein-associated estrone in human plasma and follicular fluid

Estrogen fatty acid esters constitute a unique family of extremely hydrophobic hormonal derivatives which are exclusively transported in lipoprotein particles in plasma. In estradiol, the fatty acyl residues are conjugated at the 17β-hydroxyl of the steroid D-ring, leaving the phenolic 3-hydroxyl group unsubstituted and, therefore, preserving antioxidative efficacy. The 17β-fatty acid derivative of estradiol is proposedly an even more efficient antioxidant protecting LDL and HDL than the parent steroid. Previous studies have established that the enzyme lecithin:cholesterol acyltransferase which catalyzes the fatty acid esterification of 3β-hydroxyl group of cholesterol, also catalyzes the formation of estrogen 17β-esters. Estrone, the principal estrogen in the postmenopausal female, has a keto group at carbon-17 and has been thought unable to form fatty acid esters. However, we detected hydrophobic derivatives of estrone following incubations with human plasma and ovarian follicular fluid. These derivatives accumulated in HDL and LDL during incubation showing chemical characteristics similar to estrone-3-fatty acid esters. Liquid chromatographic–mass spectrometric analyses established the presence of unhydrolyzed estrone esters consisting of different fatty acid species, the major one being estrone-3-linoleate, in human HDL particles following incubation of estrone with plasma. These extremely hydrophobic estrone conjugates could, in theory, represent a storage form of this estrogen.

Plasma estrone sulphate (E 1S) and estradiol-17β (E 2β) profiles during pregnancy and their relationship with the relaxation of sacrosciatic ligament, and prediction of calving time in Holstein–Friesian cattle

The objectives of this study were to investigate the plasma E 1S and E 2β profiles during pregnancy and their relationship with the relaxation of sacrosciatic ligament in Holstein–Friesian cattle ( n = 37) and then to predict the calving time on the basis of E 1S and E 2β profiles and relaxation of the ligament. Blood samples were collected at 4 weeks intervals from days 100 to 190, at 2 weeks intervals from days 190 to 250, every week from days 250 to 270 and thereafter every day from day 270 of gestation until the day after calving. The relaxation in the ligament was measured by using two scales as a distance at a schedule similar to blood sampling plus 5 days postpartum. One scale was kept firm exactly parallel to the ligament between the sacrum and the tuber ischii and other scale was erected perpendicularly to the first scale with the bottom just touching the ligament and the depth was measured in the second scale from the point where it touched the ligament to the point where it touched the first scale. Plasma samples were analyzed for E 1S and E 2β by enzyme immunoassay. E 1S concentration was low at day 100 (0.8 ± 0.3 ng/ml), then increased progressively and drastically to reach the level of 28.4 ± 3.6 ng/ml on the day before calving and declined significantly ( p < 0.05) at 9.5 ± 3.1 ng/ml within 1 day postpartum. There was a gradual increase in concentration of E 2β from day 100 of gestation (0.1 ± 0 ng/ml) until day 4 prepartum (0.6 ± 0 ng/ml). Thereafter, it increased drastically and reached the peak level of 1.0 ± 0.1 ng/ml ( p < 0.05) on the day before calving and declined markedly at 0.4 ± 0.1 ng/ml within 1 day postpartum ( p < 0.05). Corresponding to E 1S and E 2β concentrations, a gradual increase in the relaxation of the ligament was observed from day 100 of gestation (8 ± 1 mm) until day 2 prepartum (24 ± 2 mm). Thereafter, it showed a significant increase ( p < 0.05) within 1 day before calving (31 ± 2 mm) and almost no difference between day 1 prepartum and day 1 postpartum. A marked decrease ( p < 0.05) was observed thereafter until day 3 postpartum (10 ± 2 mm) and no significant change between days 3 and 4 as well as 4 and 5 postpartum. The increment of E 2β by ≥0.20 ng/ml from the preceding day concentration was 85.2% accurate for predicting calving within 24 h in many of the cows (23 of 37) in the herd. The increment in ligament relaxation measurement by ≥5 mm from the preceding day measurement was the most efficacious to predict calving within 24 h with the highest accuracy (93.9%) in high proportions of cows (31 of 37) in the herd. In conclusion, plasma E 1S and E 2β concentrations and relaxation of sacrosciatic ligament increased gradually as gestation advanced and reached the peak level on the day before calving. The relaxation in the ligament corresponded well to plasma E 2β concentrations. Prediction of calving was possible by E 2β profile and relaxation in the ligament but not by E 1S profile. The increment in ligament measurement by ≥5 mm from the preceding day measurement was the most useful and accurate in predicting calving within 24 h. It is economical and easily applicable in the field condition.