GnRH agonist stimulation of the pituitary-gonadal axis in children: age and sex differences in circulating inhibin-B and activin-A

BACKGROUND: Inhibin-B decreases and activin increases FSH secretion in adults. We investigated whether an FSH-inhibin/activin feedback loop exists before or during puberty. METHODS: FSH secretion was stimulated with 10 microg/kg leuprolide acetate (GnRH agonist) in 18 girls, ages 1.0-13.2 years, and 11 boys, ages 8.9-15.2 years, with variations in pubertal development, and in five normal 9- to 10-year-old girls. Blood, obtained at 0, 0.5, 1, 2, 4, 8, 12, 16, 20 and 24 h after GnRH agonist, was analysed for LH, FSH, activin-A, inhibin-A, inhibin-B, follistatin 288 and estradiol/testosterone. RESULTS: FSH increased within 30 min of GnRH agonist administration with a peak greater in girls than boys (P=0.0006). Baseline inhibin-B was greater in boys than girls (P=0.01), while baseline activin-A concentrations were greater in girls. GnRH agonist-stimulated FSH increased inhibin-B in girls by 8 h and in boys by 20 h (P<0.05), but did not affect activin-A. Inhibin-B increases were seen only in girls older than 5 years. CONCLUSIONS: An inhibin-B-FSH feedback loop exists prior to the onset of puberty in girls older than 5 years. Sex differences in activin-A and inhibin-B concentrations may be responsible for sex differences in serum FSH concentrations.     

Inhibin in extra-embryonic coelomic and amniotic fluids and maternal serum in early pregnancy

Inhibins are present in maternal serum during pregnancy. However,the presence of inhibins in the compartments surrounding thefetus in early pregnancy is not well defined. Using novel specificenzyme-linked immunosorbent assays we have demonstrated thatthe bioactive dimeric inhibin forms, inhibin-A and inhibin-B,and the immunoreactive inhibin forms containing pro- and C sequencesare present in different amounts in the extra-embryonic coelomicand amniotic fluids and maternal serum between 8–11 weeksgestation. Of the bioactive dimeric inhibins, both inhibin-A(mean ± SEM 236.0 ± 24.8 pg/ml) and inhibin-B(62.0 ± 8.6 pg/ml) are present in extra-embryonic coelom,whereas no dimeric inhibin is present in the amniotic fluidand only inhibin-A (360.2 ± 32.9 pg/ml) is present inmaternal serum. Furthermore, pro-C-related immuno-reactivityis present at high concentrations in the extra-embryonic coelom(591.7 ± 60.5 pg/ml), amniotic fluid (452.4 ±76.8 pg/ml) and maternal serum (539.4 ± 39.5 pg/ml).These findings would indicate that at this stage of gestationinhibin-A, inhibin-B and immunoreactive pro-C-containing inhibinproduction are likely to arise from different sources includingthe fetus, placenta and fetal membranes and maternal sourcesincluding the ovary. Inhibins may be important regulators offetal and placental development and involved in the establishmentof pregnancy.     

Sex differences in FSH-regulatory peptides in pubertal age boys and girls and effects of sex steroid treatment

BACKGROUND: FSH concentrations are higher in girls than in boys before puberty. We hypothesized that steroid-mediated changes in FSH-regulatory proteins underlie the sex differences in FSH secretion and pubertal timing. METHODS: FSH-regulatory proteins, LH, FSH and sex steroids were measured in five boys, 10 girls, and five girls with Turner syndrome before and during sex steroid treatment (girls, 0.05 mg/day estradiol; boys, 5 mg/day testosterone) for up to 4 weeks. Blood was obtained every 15 min from 20.00 to 08.00 h before and during sex steroid treatment. RESULTS: The mean FSH concentration was higher in girls than in boys (P = 0.0044). Activin-A concentrations were greater (P < 0.0001) and inhibin-B concentrations lower (P < 0.0001) in girls compared with boys. Steroid treatment (i) suppressed LH/FSH concentrations in all subjects; (ii) increased the mean activin-A concentration in all but the Turner girls (P = 0.001); and (iii) decreased inhibin-B concentrations in boys (P = 0.005) but not in girls. Total follistatin and follistatin 288 concentrations did not differ by sex. CONCLUSIONS: Sex steroids regulate circulating activin-A and inhibin-B concentrations in children. The lower inhibin-B and higher activin-A concentrations may explain the higher FSH and earlier onset of puberty in girls.     

Relationship between follicle size and gonadotrophin surge attenuating factor (GnSAF) bioactivity during spontaneous cycles in women.

BACKGROUND: We have previously demonstrated that follicles < or =11 mm diameter from women undergoing IVF contain higher concentrations of gonadotrophin surge attenuating factor (GnSAF) bioactivity than large follicles from the same ovaries. METHODS: To determine whether this finding is relevant to spontaneous cycles, follicular fluid aspirated from 37 follicles between 3 and 25 mm in diameter from 14 pairs of ovaries from regularly cycling women undergoing total abdominal hysterectomy and bilateral salpingoophorectomy for benign gynaecological disease was pooled into size categories (3 + 4, 5 + 6, 7 + 8, 9 + 10, 11 + 12, 14 + 15, 18 and 25 mm). These pools were bioassayed for GnSAF and inhibin-A, inhibin-B and activin-A concentrations were determined. RESULTS: Follicles of 5 + 6 mm diameter contained the highest concentrations of GnSAF bioactivity (reducing GnRH-induced LH secretion to 38 +/- 8% of control, P < 0.001), while those of 25 mm diameter contained one quarter of this concentration (reducing GnRH-induced LH secretion to 72 +/- 2% of control, P < 0.05). GnSAF bioactivity was closely related to follicle size (r = -0.836, P < 0.01), but not to inhibin-A, inhibin-B or activin-A concentrations. CONCLUSIONS: The finding that small follicles contain high concentrations of GnSAF bioactivity, which fall as folliculogenesis progresses during spontaneous cycles, support the hypothesis that GnSAF has a role in preventing the premature onset of the LH surge in women.     

Serum activin A and follistatin concentrations during human pregnancy: a cross-sectional and longitudinal study

Activin A, a dimer of the betaA-subunit of inhibin, has been shown to have multiple biological activities and sites of production. Follistatin is a high-affinity binding protein for activin, which neutralizes its activity. This study provides the first data, using a cross-sectional design, on the measurement of both these proteins in the maternal circulation of a large cohort of women (6-39 weeks of gestation, n = 2-20 women/time point) during normal pregnancies, and confirms that similar patterns are seen in nine women studied longitudinally during pregnancy. The concentrations of total activin A were measured using a specific two-site enzyme-linked immunosorbent assay (ELISA), and a new radioimmunoassay for measuring total follistatin in serum utilizing dissociating reagents to eliminate the interference of activin is described. At 38-39 weeks gestation, both activin A and follistatin concentrations rose to a peak (4.59 +/- 0.54 ng/ml and 72.7 +/- 3.31 ng/ml, respectively). The activin A and follistatin concentrations were highly correlated both in the cross-sectional study (P <0.0001) and in individual women in the longitudinal study (P <0.05-0.0001). Concentrations of follistatin showed a greater increase in the second trimester of pregnancy relative to activin A concentrations. The parallel increase in the secretion of these two proteins throughout pregnancy probably reflects feto-placental secretion.     

Circulating follistatin concentrations are higher and activin concentrations are lower in polycystic ovarian syndrome

Familial polycystic ovarian syndrome (PCOS) has been proposed to be linked to a site near the follistatin gene. We studied the concentrations of circulating follistatin, activin A and inhibin B in well-characterized subjects with PCOS (n = 108) and controls without PCOS (n = 20). Mean (+/- SEM) concentrations of follistatin were higher (P < 0.05) in PCOS (0.27 +/- 0.03 ng/ml) than controls (0.15 +/- 0.02 ng/ml) and activin A were lower (P < 0.05) in PCOS (0.20 +/- 0.01ng/ml) than controls (0.24 +/- 0.02 ng/ml). Inhibin B concentrations were not different between the two groups: PCOS (0.06 +/- 0.01ng/ml), and controls (0.06 +/- 0.01ng/ml). It is proposed that higher concentrations of follistatin with lower concentrations of activin A may relate to follicular development not proceeding beyond 8-10 mm and may be partly responsible for the lack of pre-ovular follicle development in PCOS.     

Inhibin- A and Pro-αC Are Elevated in Preeclamptic Pregnancy and Correlate with Human Chorionic Gonadotropin

PROBLEM: Serum concentrations of the heterodimeric glycoprotein inhibin-A (α-β_A) and its α-subunit increase during pregnancy. The placenta is the predominant source of inhibin during pregnancy, and a paracrine role in the trophoblast has been suggested. Elevated serum concentrations of inhibin α-subunit as well as the glycoprotein human chorionic gonadotropin (hCG) have been described in preeclamptic pregnancy. The objectives of this investigation were to compare serum concentrations of inhibin-A and inhibin pro-αC in preeclamptic and normotensive pregnancy, and to examine the relationship of hCG and inhibin-A in those pregnancies. METHOD OF STUDY: A case-control design using 32 patients with preeclampsia with a single fetus at 32–40 weeks of gestation and 34 gestation age-matched normotensive control subjects was used for this investigation. Solid-phase enzyme-linked immunosorbent assays were used to measure inhibin-A and inhibin pro-αC in sera. An immunoradiometric assay was used to measure intact hCG. RESULTS: Inhibin-A and inhibin pro-αC concentrations were significantly elevated in the sera of women with preeclampsia compared with those concentrations in normotensive control subjects (P < 0.05). A relationship of inhibin-A or pro-αC with severity of preeclampsia was not observed. There was a significant positive correlation of serum hCG with both inhibin-A and pro-αC (P < 0.05). CONCLUSIONS: Levels of inhibin-A and the subunit pro-αC are increased in pregnancies complicated by preeclampsia. These findings are potentially the effect of a paracrine role of inhibin-A in the development and proliferation of the trophoblast.     

Follistatin and activin A serum concentrations in obese and non-obese patients with polycystic ovary syndrome.

BACKGROUND: Activin promotes ovarian follicular development, inhibits androgen production and increases FSH and insulin secretion. Follistatin, an activin-binding protein, neutralizes activin bioactivity. Therefore, a decrease in the ratio of activin/follistatin might encourage characteristic features of polycystic ovary syndrome (PCOS). We investigated whether women with PCOS showed disordered follistatin and/or activin serum concentrations. METHODS: The study group included 24 obese and 20 non-obese (body mass index vertical line and <27 kg/m2 respectively) clomiphene-failure PCOS patients. The control group included 16 obese and 46 non-obese patients with normal ovulatory cycles. Blood samples were obtained from the patients on day 3-5 of a progesterone-induced or spontaneous cycle and were assayed for LH, FSH, testosterone, 17-hydroxy-progesterone, androstenedione, follistatin, activin A, fasting glucose and insulin. RESULTS: Follistatin concentrations were comparable between obese and non-obese PCOS patients (mean +/- SE; 1171 +/- 103 and 1045 +/- 159 pg/ml respectively) and significantly higher than their respective controls (628 +/- 61 and 592 +/- 49 pg/ml, P < 0.0001 and P < 0.02 respectively). Activin A concentrations were comparable between the four groups (590 +/- 35, 513 +/- 74, 661 +/- 87 and 595 +/- 43 pg/ml in obese and non-obese PCOS and controls respectively). Stepwise regression analyses for relationships between follistatin or activin A levels and all other variables indicated that follistatin was significantly and independently positively affected by PCOS (P < 0.0001), age (P < 0.02), androstenedione (P < 0.03) and weight (P < 0.05). Activin A was significantly and independently negatively affected by PCOS (P < 0.003) and FSH (P < 0.03), and positively affected by weight (P < 0.009) and androstenedione (P < 0.02). CONCLUSIONS: Serum follistatin is increased in PCOS patients, regardless of obesity. PCOS is the most significant variable that relates to high follistatin and low activin A serum concentration. A high follistatin/activin ratio could well contribute to the pathophysiology of PCOS.     

Ultrasensitive two-site assays for inhibin-A and activin-A using monoclonal antibodies raised to synthetic peptides.

Monoclonal antibodies produced to synthetic peptides of the alpha and beta A subunits of inhibin were used to develop the first highly sensitive two-site assays for recombinant human inhibin-A and activin-A. The assay for inhibin-A could detect as little as 5 pg/ml. Activin-A gave a 5.2% cross-reactivity in the inhibin assay. The assay for activin-A could detect 0.1 ng/ml and inhibin-A showed a 5.3% cross-reaction in the activin assay. Determination of inhibins and activins in biological fluids is complicated by the presence of multiple molecular forms and an excess of free alpha subunits. The present study demonstrates the potential of antibodies raised to synthetic peptides to configure more specific two-site assays for inhibins and activins which could facilitate research on these molecules. The monoclonal antibody used as the labelled antibody in these studies was made by immunizing mice with a peptide corresponding to an internal sequence of the beta A subunit. It appears likely that similar high affinity anti-peptide monoclonals suitable for use in ultrasensitive two-site assays could be made to other molecules if a rigorous screening of the fusion supernatants on the native molecule was carried out. The use of anti-peptide monoclonal antibodies in the development of ultrasensitive immunoassays may be more widely applicable than commonly realised.     

Inhibin-B as a test of ovarian reserve for infertile women.

The objective of the study was to compare a standard clomiphene citrate challenge test with inhibin-B serum concentrations also obtained on cycle days 3 and 10 as a negative predictor of pregnancy in a group of 106 women at risk for compromised ovarian function. Mean duration of follow-up was 8.25 months in 95 patients with 30 pregnancies recorded (plus one biochemical). Inhibin-B concentrations on cycle days 3 and 10 were correlated only with each other and not with serum oestradiol, follicle stimulating hormone (FSH) and/or pregnancy rates. Pregnancy occurred in 34.5% (10/29) of all patients with inhibin-B values >/=45 pg/ml on cycle day 3 and in 31.8% (21/66) of those with values <45 pg/ml. For FSH >11 mIU/ml on either day, pregnancy rate was 13.6% versus 38.4% for FSH of 相似文献   

Leptin and leptin-binding activity in women with recurrent miscarriage: correlation with pregnancy outcome

BACKGROUND: Previous studies in humans and mice have suggested the importance of leptin in fetal growth. Recurrent miscarriage may be a result of abnormal placental and/or fetal development and therefore abnormal leptin levels may be associated with this form of pregnancy loss. METHODS: Leptin and leptin-binding activity (LBA) were measured in blood obtained from women who had a history of recurrent miscarriage (n = 53) during weeks 5-6 and 7-8 of pregnancy, and the concentrations were correlated with subsequent pregnancy outcome. RESULTS: Concentrations of leptin ranged from 1.4-62.8 ng/ml, but there was a strong correlation (r = 0.825, P < 0.001) between leptin values at weeks 5-6 and 7-8 in the same woman. Women who subsequently miscarried had significantly lower plasma leptin concentrations on both weeks 5-6 (13.34 +/- 2.1 ng/ml) (P < 0.05) and 7-8 (13.71 +/- 2.4 ng/ml) (P < 0.01) of pregnancy, than women who subsequently had a term birth (22.04 +/- 2.43 ng/ml week 5-6, 24.76 +/- 3.66 ng/ml week 7-8). LBA values ranged from 1-8.5% but there was no significant difference in LBA in blood obtained from women who subsequently miscarried or had a live birth. CONCLUSIONS: The significantly lower concentrations of leptin in women who subsequently miscarried suggest that leptin may play a role in preventing miscarriage. However, as there was a considerable overlap between the values of leptin in women who subsequently miscarried, and those that had a live birth, these measurements are of limited use in the prediction of pregnancy outcome in these women.     

Basal and stimulated plasma atrial natriuretic peptide (ANP) concentrations and cardiac ANP contents in old and young rats.

To investigate the ability of the ageing heart to release atrial natriuretic peptide (ANP) we compared the response of awake, trained, chronically catheterized old (20-21 months) and young (4 months) rats to an acute, hypertonic saline challenge. There were no differences between young and old rats in basal plasma concentration of sodium (PNa; old: 141 +/- 3 meq/l; young: 143 +/- 3 meq/l) or ANP (old: 61 +/- 5 pg/ml; young: 67 +/- 12 pg/ml). Five minutes after acute saline challenge, PNa rose in both groups (old: 146 +/- 2 meq/l; young 149 +/- 1 meq/l) and approximately 3-fold increases in plasma ANP levels (182 +/- 24 pg/ml; young: 179 +/- 42 pg/ml). Hearts of old and young rats were assayed for atrial and ventricular ANP content. Atrial ANP levels were similar in old and young rats (13.5 +/- 3.6 vs. 24.9 +/- 8.7 micrograms/g atrial tissue), whereas ventricular ANP content was approximately 4-fold higher in old vs. young rats (153.7 +/- 39.3 vs. 47.5 +/- 6.4 ng/g ventricular tissue). Thus, the ageing rat heart responds equally as well as the young rat to an acute NaCl challenge.     

Critically low hormone and catecholamine concentrations in the primed extracorporeal life support circuit

The first hours of extracorporeal life support (ECLS) are commonly marked by new hemodynamic instability without a known etiology. We measured hormone and catecholamine concentrations in six ECLS primed circuits immediately before joining the patient's circulation to assess a potential role of these agents in this condition. The following hormones were significantly below the lower end of the normal range for the first week of life (data are presented as mean +/- SEM): cortisol 1.95 +/- 0.15 microg/dl (p < 0.001), aldosterone 3.73 +/- 0.74 ng/dl (p < 0.05), free thyroxine 1.2 +/- 0.1 ng/dl (p < 0.05), free triiodothyronine 0.53 +/- 0.03 pg/ml (p < 0.001), thyroid stimulating hormone 0.31 +/- 0.05 microU/ml (p < 0.001), growth hormone (GH) 0.09 +/- 0.01 ng/ml (p < 0.001), estradiol 38.3 +/- 3.72 pg/ml (p < 0.001), IGF-BP1 0.95 +/- 0.1 ng/ml (p < 0.001), glucagon 26 +/- 1.2 pg/ml (p < 0.001), epinephrine 17.3 +/- 3.7 pg/ml (p < 0.001), and norepinephrine 127 +/- 27 pg/ml (p < 0.05). No dopamine was detected. Normal hormone concentrations included IGF-I, IGF-BP3, insulin, parathyroid hormone, leptin, and testosterone. Critically low concentrations of cortisol, thyroid hormones, GH, IGF-BP1, glucagon and catecholamines were measured in the ECLS circuit even though it was primed with fresh frozen plasma. These concentrations may cause significant and precipitous dilutional reductions in the patient's circulating levels immediately after connection to the ECLS circuit and hence contribute to hemodynamic instability.     

Renin and angiotensin-like levels in foetal, new-born and adult sheep

1. Plasma renin (measured as rate of formation of angiotensin I ng/ml.hr(-1) in the presence of added substrate at pH 7.5 and 37 degrees C) was much lower in recently nephrectomized foetal, new-born and older lambs than in intact siblings or other similar lambs.2. Angiotensin II-like concentrations were measured using a superfusion technique in an extracorporeal circuit. Resting concentrations in acute experiments under anaesthesia were deduced by comparison of carotid blood of intact lambs with that from recently nephrectomized lambs.3. Angiotensin II-like activity (mean +/- S.E. of mean, 315 +/- 117 pg/ml.) was readily detectable in foetal blood at 123-138 days gestation. The highest concentrations (mean +/- S.E. of mean 839 +/- 96 pg/ml.) were found in lambs less than 8 hr old, delivered vaginally. The lowest concentrations of angiotensin II-like activity occurred in lambs delivered by Caesarean section (mean +/- S.E. of mean < 123 +/- 12 pg/ml.). Concentrations declined with post-natal age.4. Hypovolaemia as a result of haemorrhage evoked an increase in angiotensin II-like concentrations in foetus, new-born lambs and adult sheep. The greatest increase of angiotensin-like concentrations was seen in new-born lambs. This rise was associated with increase of plasma renin.5. The rise of arterial pressure during bilateral carotid occlusion in new-born lambs was accompanied by an increase of angiotensin II-like concentration.6. It is concluded that the renin-angiotensin system is functional and can be stimulated during intra-uterine life. The increase of angiotensin II-like concentration following parturition is probably transient and associated with the trauma of delivery. This contrasts with observations made in the rabbit which suggest that full functional maturity of the renin angiotensin system is delayed until the second week of life.     

Elevated serum progesterone on the day of HCG administration in IVF is associated with a higher pregnancy rate in polycystic ovary syndrome

Our study compared 84 patients with polycystic ovary syndrome (PCOS) with 84 control patients who had normal ovaries and who were matched for the main determinants of success in in-vitro fertilization (IVF) and embryo transfer. Serum concentrations of oestradiol and progesterone on the day of human chorionic gonadotrophin (HCG) injection were significantly higher in PCOS than in normal patients (oestradiol 2016 +/- 1.8 pg/ml versus 1456 +/- 40.9 pg/ml, P < 0.01; progesterone 1.6 +/- 0.1 ng/ml versus 1.2 +/- 0.1 ng/ml, P = 0.03). Furthermore despite oocytes from PCOS patients having a reduced fertilization rate compared with normal patients (61.8 +/- 4.1% versus 73.5 +/- 4.3%, P = 0.03), the differences in pregnancy rate (22.6 versus 19%) and miscarriage (31.5 versus 18.7%) were not statistically significant. In PCOS patients, a critical breakpoint was identified at serum progesterone concentrations of 1.2 ng/ml on the day of HCG injection. The PCOS patients with progesterone > or = 1.2 ng/ml showed a higher pregnancy and miscarriage rate than PCOS patients with progesterone < 1.2 ng/ml (26.6 versus 17.9%, P < 0.01; and 41.7% versus 14.3%, P < 0.01 respectively). These findings suggest that premature progesterone production does not have an adverse effect on pregnancy rate in PCOS, but on the contrary, may be a predictor for success in IVF/embryo transfer.     

Rabbit endocervical epithelium: morphometric analysis of secretory cell populations

In this report we quantitated ultrastructural changes in two cytologically distinct secretory cell populations from the rabbit endocervix. Type I and type II cells from estrous animals differ only in the presence of one or more empty cytoplasmic vacuoles in type II cells. Comparing type II cells from 5-day pseudopregnant (PSP) rabbits with type II cells from estrous controls, there is no increase (P greater than .05) in the average vacuole volume. When type I and type II cells from PSP animals are compared to cells from estrous controls, there is a decrease (P less than .01) in the average cell volume, a decrease (P less than .01) in the average nuclear volume, and a decrease (P less than .01) in the average granule volume. This reduction in the granule content of secretory endocervical cells was correlated with a dramatic decrease in protein glycosylation into the microsomal fraction. Serum estradiol concentrations for estrous (13.7 +/- 1.0 pg/ml) and PSP (18.1 +/- 1.5 pg/ml) animals were comparable. However, the 36-fold increase in serum progesterone concentrations for PSP (12.04 +/- 1.7 ng/ml) animals compared to estrous (0.33 +/- 0.1 ng/ml) animals may be responsible for the decrease in protein glycosylation.     

Follistatin and activin A in extra-embryonic coelomic and amniotic fluids and maternal serum in early pregnancy

Follistatin is a specific binding protein which controls bioavailability of activins and inhibins which have an important role in fetal development. In the first trimester of pregnancy bioactive dimeric inhibins are found at high concentrations in the extra- embryonic coelomic fluid, but the distribution of follistatin and activins is not known. We have used recently developed immunoassays for follistatin, activin A and activin AB to determine their presence in the intrauterine compartments during early pregnancy. Follistatin was present in highest concentrations in the extra-embryonic coelomic fluid (11.72 +/- 1.70 ng/ml; median +/- SEM), with less in maternal serum (6.35 +/- 4.58) and lowest amounts in amniotic fluid (0.97 +/- 0.52). Follistatin concentrations in extra-embryonic coelomic fluid were highly correlated with both dimeric inhibin isoforms. Activin A was present in only barely detectable amounts in some samples of extra- embryonic coelomic fluid (41% of samples) and maternal serum (26%) and was undetectable in all amniotic fluid samples. Activin AB was undetectable in all compartments. The presence of follistatin in the amniotic and extra-embryonic coelomic fluids may regulate the availability of bioactive activins and inhibins which are released into the intrauterine compartments during the development of the fetus and placenta in early pregnancy.      

Endometrial thickness and oestradiol concentration in women with bleeding complaints during use of Norplant implants

The objective of this study was to measure oestradiol, progesterone and endometrial development among Norplant implant users with bleeding complaints. Seventy-six volunteers complaining of prolonged/frequent bleeding were enrolled. Oestradiol, progesterone and endometrial thickness (assessed by vaginal ultrasound) were determined at that visit. Two thirds of the women had low oestradiol (< 50 pg/ml) and all except one had low progesterone concentrations (< 3 ng/ml). A total of 68% had a very thin endometrium (< 3 mm). A subgroup of 21 women were followed twice a week for 8 consecutive weeks. Oestradiol and progesterone concentrations remained low during the continuous bleeding episodes or short bleeding-free intervals (< or = 15 days), yet increased five- to sixfold (253.4 +/- 142.2 pg/ml) in long bleeding- free intervals. Endometrial thickness remained thin irrespective of the differences in bleeding patterns and oestradiol. We conclude that Norplant implant users with bleeding complaints are usually characterized by low oestradiol concentrations, absence of luteal activity and thin endometrium. A good correlation exists with increasing oestradiol concentrations and longer bleeding-free intervals, but this is not manifested by increased endometrial thickness. However, few subjects bleed with relatively high oestradiol concentrations, therefore a better understanding of the intimate disturbances related to endometrial bleeding in users of long-acting progestins is still pending.      

Low-dose aspirin in prevention of miscarriage in women with unexplained or autoimmune related recurrent miscarriage: effect on prostacyclin and thromboxane A2 production

Early pregnancies in women with a history of recurrent spontaneous abortion (RSA) are accompanied by a deficiency in vasodilatory and anti- aggregatory prostacyclin (PGI2) and/or overproduction of its endogenous antagonist thromboxane A2 (TXA2). We evaluated the effect of a low-dose aspirin (LDA) on PGI2 and TXA2 production and on pregnancy outcome in RSA women with and without detectable anticardiolipin antibodies (ACA). Of 82 RSA women studied, 66 became pregnant, and of them, 33 (six with elevated and 27 with normal ACA concentrations) were randomized to receive LDA (50 mg/day) and 33 (six with elevated and 27 with normal ACA concentrations) to receive placebo (PLA) from a mean of 6.6 days after the missed period to delivery. Treatment with LDA inhibited platelet TXA2 production similarly in RSA women with and without detectable ACA and with continuing pregnancies (7.0 +/- 0.7 ng/ml, LDA group versus 254.5 +/- 37.8 ng/ml, PLA group, mean +/- SEM, P < 0.0001) or miscarrying pregnancies (13.8 +/- 3.8 ng/ml compared with 233.6 +/- 59.8 ng/ml, P < 0.0001 respectively). Furthermore, LDA decreased urinary excretion of the TXA2 metabolite (2,3-dinor-TXB2) both in pregnancies which went to term (6.1 +/- 0.6 ng/mmol creatinine, LDA group versus 19.3 +/- 3.0 ng/mmol creatinine, PLA group, P < 0.0001) or again ended in miscarriage (4.7 +/- 0.8 ng/mmol creatinine versus 17.3 +/- 4.4 ng/mmol creatinine, P < 0.0001 respectively), but did not affect the excretion of the prostacyclin metabolite (2,3-dinor-6-keto- PGF1alpha). Early pregnancy ultrasound examination revealed a living fetus in 58 women. Of these, seven in the LDA group (23.3%, four with elevated and three with normal ACA concentrations) and five in the PLA group (17.9%, two with elevated and three with normal ACA concentrations; not significant) experienced a miscarriage. All infants were healthy, and the frequency of growth retardation was similar in both groups (13.0%). One woman in the LDA group (4.3%) and three women receiving PLA (13.0%) developed pre-eclampsia (not significant). Therefore, although treatment with LDA caused a desirable biochemical effect, it did not improve pregnancy outcome in RSA women with or without detectable ACA.      

Inhibin A, inhibin B and activin A in the follicular fluid of regularly cycling women

Recent measurements of circulating inhibin A and inhibin B concentrations indicate that inhibin B may play an important role in the selection of dominant follicles. The concentrations of inhibin A, inhibin B and activin A were measured in the follicular fluids of 61 individual follicles (4.8-20 mm in diameter) from 47 regularly cycling women using specific two-site enzyme-linked immunosorbent assays. The microenvironment of each follicle was characterized by measuring follicular fluid androstenedione and oestradiol concentrations. The mean activin A concentrations were < 8 ng/ml for follicles of all sizes (4-17 mm). Inhibin A concentrations were < 1 ng/ml in follicles < 6 mm, and progressively increased to concentrations > 50 ng/ml in follicles > or = 13 mm. Follicles with androstenedione/oestradiol ratios < or = 4 had higher concentrations of inhibin A than follicles with androstenedione/oestradiol ratios > 4. Inhibin B concentrations were higher than inhibin A concentrations in all follicles, increasing from 19.2 +/- 8.3 ng/ml in 4 mm follicles to 409 +/- 9.6 ng/ml in 13 mm follicles and then declining to 275 +/- 47 ng/ml in 17 mm follicles. These results support the hypothesis that inhibin B may play a more important paracrine role in developing follicles and a greater regulatory role with respect to follicle stimulating hormone (FSH) secretion than inhibin A.