LH Values Research Articles

The Gonadotrophins Response to GnRH Test is Not a Predictor of Neurological Lesion in Girls with Central Precocious Puberty

To assess the value of gonadotrophin releasing hormone (GnRH) stimulation test in identifying intracranial abnormality in girls with central precocious puberty (CPP). A study of 67 girls diagnosed with CPP who underwent cranial MRI scans. Patients were not receiving any therapy and there were no neurological signs or symptoms at presentation. Patients underwent evaluation of GnRH stimulation test and plasma oestradiol levels at presentation. Mean age at onset of puberty was 6.2 years (range 2.0 to 8.0 years). Intracranial abnormalities were present in 10 (15%) patients, while 57 girls (85%) had no abnormalities. No significant difference was shown between girls with intracranial abnormality and girls without intracranial abnormality in basal LH or FSH values, peak LH or FSH values, LH/FSH peak ratios, peak LH/basal LH ratios, peak FSH/ basal FSH ratios at presentation. GnRH stimulation test does not identify those with underlying intracranial abnormality at presentation. MRI imaging remains necessary in all cases of central precocious puberty in girls.

Defining menopause status: creation of a new definition to identify the early changes of the menopausal transition

Several menopausal staging definitions are currently being used in ongoing studies designed to identify changes occurring during menopause. The objective of this study was to determine which definition captures the earliest hormonal changes in the menopausal transition. In this prospective cohort study, women aged 35 to 47 years were followed for 5 years. Women were classified as premenopausal, early transition, late transition, and postmenopausal by 2 different menopausal staging systems defined by bleeding patterns. Definitions from the Study of Women Health Across the Nation (SWAN) and Stages of Reproductive Aging Workshop (STRAW) were compared. A new menopausal staging system (PENN-5) was also developed with five groups rather than four to distinguish among women with more subtle changes in cycle length. For each staging system, a linear regression model was created comparing mean hormone values (inhibin B, FSH, LH, E2) and menopausal stages at each assessment. Race, body mass index, cycle day, smoking, and follow-up time were included in the model. Statistically significant differences in mean inhibin B and FSH levels, but not estradiol levels, were detected between the earliest menopausal stages of each definition. Significant differences in LH values were detected among the earliest stages of the SWAN and STRAW definitions, but not the PENN-5 definition. Subtle changes in menstrual cycle length reflect significant changes in inhibin B and FSH levels during the menopausal transition. Therefore, it appears that subtle changes in bleeding pattern may be helpful in identifying the earliest hormonal changes during menopausal transition.

Follicular phase serum levels of luteinizing hormone do not influence delivery rates in in vitro fertilization cycles down-regulated with a gonadotropin-releasing hormone agonist and stimulated with recombinant follicle-stimulating hormone

To assess the value of serum LH measurements in early and late follicular phase as predictors of ovarian response and IVF outcome in patients treated with recombinant FSH with GnRH agonist (GnRH-a) pituitary down-regulation. Retrospective cohort analysis. Institutional. Women undergoing 157 consecutive IVF cycles suppressed with leuprolide acetate (LA) started in the midluteal phase and stimulated with recombinant FSH. Only women <40 years of age and with a basal cycle day 3 serum FSH </=9 IU/L were included. Serum LH levels were measured on cycle days 3 (D3) and 10 (D10). Delivery rates. Other secondary outcome measures included fertilization rate, clinical pregnancy rate, and parameters of ovarian response (peak E(2), number of metaphase II oocytes, and number of ampules of recombinant FSH). No significant differences were found with respect to ovarian response, fertilization rate, and outcome of pregnancy, when three threshold values of D3 and D10 serum LH (1, 1.5, and 2 mIU/mL) were analyzed. In addition, no significant differences were found between conception (n = 87) and no conception (n = 71) groups with respect to D3 or D10 LH. Receiver operator characteristic (ROC) analysis showed that neither the serum LH concentration on D3 nor on D10 was able to discriminate between conception and nonconception cycles (area under the curve [AUC](ROC)= 0.54, AUC(ROC)= 0.56), or between delivered pregnancies and first trimester pregnancy loss (AUC(ROC)= 0.53, AUC(ROC) = 0.61). The suppressed levels of early and late follicular serum LH in women <40 years of age with normal ovarian function desensitized with a GnRH-a and treated with recombinant FSH are not predictive of ovarian response, pregnancy, or delivery. These data do not support the use of exogenous LH supplementation in this clinical scenario.

Fertility in Male Patients with Hodgkin's Disease - Results from the German Hodgkin Lymphoma Study Group (GHSG).

Background:Treatment results in Hodgkin Disease (HD) have improved tremendously over the last two decades. Therefore long term sides effects of therapy as infertility are of growing importance. However, patients (pts) with HD have increased risk for inadequate semen quality even prior to treatment. To investigate the influence of disease and therapy on the fertility status in pts with HD we performed semen and hormone analysis before and after treatment.Patients and Methods:All analysis were evaluated in pts with first diagnosis of HD enrolled into trials of the GHSG between 1988 and 2002, in 40 centers in Europe. Pts had no history of chemotherapy or radiotherapy. All analysis were evaluated according to WHO-guidelines.Results:We included 243 male pts with a median age of 26,5 years (range 16–57,5 years). At first diagnosis 138 pts were in clinical stage (CS) I/II, 105 in CS III/IV, and systemic symptoms were present in 106 pts. 202 pts underwent fertility screening before therapy: normospermia was diagnosed in 40 (20%) pts and 162 (80%) had inadequate semen quality. Normal values of FSH, LH, and testosterone were found in 140/151 (93%), 99/125 (79%), and 84/101 (83%) of pts respectively. 112 pts underwent at last one fertility screening after therapy. Treatment consisted of chemotherapy alone in 10 pts, in 9 pts of radiotherapy alone and in 93 pts of combined modality. In 40 (36%) pts a recovery of spermatogenesis was observed. Normal values of FSH, LH, and testosterone after treatment were found in 32/63, 40/51, and 36/40 pts respectively. Table 1 shows time of onset of spermatogenesis and normal values of fertility hormones after the end of therapy.Table 11st year2nd year3rd yearafter 3rd yearSpermatogenesis (40/112)7 (18%)9 (24%)10 (26%)14 (32%)Normal FSH (32/63)8 (25%)12 (38%)6 (19%)6 (19%)Normal LH (40/51)13 (33%)16 (40%)6 (15%)5 (13%)Normal testosterone (36/40)17 (47%)12 (33%)1 (3%)6 (17%)Recovery from azoospermia was observed in 8 (89%) pts treated with radiotherapy, in 1 (10%) pt treated with chemotherapy alone and in 31 (33%) pts treated with combined modality. Recovery rate from azoospermia was lower in pts treated with alkylating agents, BEACOPP chemotherapy, with systemic symptoms and elevated BSG.Conclusions:We confirmed that HD pts had inadequate semen quality even prior to treatment. The majority of pts had azoospermia after treatment, but recovery of spermatogenesis was observed, in general 2 years after the end of therapy. Hormone values usually recovered in the first two years. Patient treated with radiotherapy alone recovered in higher frequency. A detailed analysis (including multivariate analyses) will be presented at the annual meeting.

Mullerian inhibiting substance (MIS) reflects ovarian and biochemical aberrations in polycystic ovary syndrome (PCOS) better than Inhibin B

MIS, also known as anti-Mullerian hormone (AMH), a member of the TGFβ superfamily, is a product of granulosa cells and is expressed in females postnatally. Recently, data have suggested that MIS may reflect the size of the antral follicle pool, and therefore may be a useful marker of ovarian aging. Also, a few reports have suggested that MIS levels are higher in women with PCOS, but there is incomplete information regarding elevations when compared to age and weight matched controls, as well as relationships to ovarian morphology, levels of inhibin B (another putative marker of antral follicle health), and other reproductive hormones. Prospective observational trial in PCOS and matched controls. Fifty women with PCOS were recruited based on the classic criteria of chronic anovulation and hyperandrogenism. These women (age 25.8 ± 0.5 yrs; BMI 29.1 ± 0.9) were compared to 34 age (25.4 ± 0.8 yrs) and BMI (27.5 ± 0.6) matched ovulatory controls. Fasting blood was obtained in all subjects in the early follicular phase (days 5–6) after spontaneous or induced menses (in PCOS), as was vaginal ultrasound for assessments of ovarian volume and blood flow. Women with PCOS had higher LH (14.0 ± 0.9 vs. 9.1 ± 0.3 mIU/ml), testosterone (T, 103±7 vs. 43±3 ng/dl), and androstenedione (A, 3.6 ± 0.2 vs. 1.6 ± 0.1 ng/ml), as well as higher insulin (19.5 ± 1.2 vs. 7.3 ± 0.5 μU/ml) and lower QUICKI (0.31 ± 0.003 vs. 0.37 ± 0.003), p < 0.01. Ovarian volume was higher in PCOS (12.0 ± 0.9 vs. 4.7 ± 0.2 cc), and the pulsatility index was lower (1.4 ± 0.05 vs. 2.5 ± 0.1), p < 0.01. Inhibin B concentrations were higher in PCOS (70 ± 8.0 vs. 40 ± 3.4 pg/ml), as were MIS levels (6.7 ± 0.9 vs. 4.6 ± 0.5 ng/ml), p < 0.05. While inhibin B correlated directly with levels of MIS (r = 0.351, p < 0.01), inhibin B did not correlate with ovarian size or reproductive hormones, insulin or QUICKI. However, MIS correlated positively with ovarian size (r = 0.350, p < 0.05), LH (r = 0.312, p < 0.01), T (r = 0.280, p < 0.05), A (r = 0.389, p < 0.01), and estradiol (r = 0.281, p < 0.05), but MIS did not correlate with ovarian blood flow. In addition, MIS correlated positively with insulin (r = 0.249, p < 0.05) but not with BMI. Women with PCOS with the highest levels of MIS had higher ovarian volumes and values of LH, T, A, and insulin. These data suggest that MIS may be an important biochemical marker in PCOS and elevated levels may relate to the pathophysiology of the ovarian dysfunction.

Post-Operative Evaluation of Anterior Pituitary Function in a Nigerian with Hyperprolactinaemia: A Case Report and Review of Literature

Prolactinoma is an endocrine abnormality associated with hyperprolactinaemia of which there is paucity of data in this environment probably due to under-reporting, under diagnosis and inadequate skill for management. This is a report of a 42 year old Nigerian who underwent surgery for pituitary prolactinoma in Western Germany and was referred to our hospital for assessment of anterior pituitary reserve on return to Nigeria. Basal values of glucose, cortisol, T3, T4, TSH, LH, FSH, and prolactin were measured following which a triple function test was conducted by intravenous administration of a bolus consisting of 250ug of ACTH, 200ug TRH and 100ug GnRH. Basal values demonstrated normoglycaemia and euthyroidism while responses to TRH and GnRH indicated restoration of anterior pituitary capacity for synthesis and control of TSH, LH, FSH and prolactin post-operatively. (Key words: Hyperprolactinaemia, Hypophysectomy, Triple function test, Immunoassay). Sahel Medical Journal Vol.7(1) 2004: 41-45

Is routine hormonal measurement necessary in initial evaluation of men with erectile dysfunction?

To prospectively compare serum hormone levels and the incidence of hormonal pathologies between men with and without erectile dysfunction, and investigate risk factors that might predict hormonal pathologies in men complaining of erectile dysfunction. The study included 262 men with erectile dysfunction and 53 healthy men with no erectile dysfunction as a control group. All men enrolled in the study were evaluated with a detailed history, physical examination, international index of erectile function (IIEF-5), and serum hormone measurement. Hypotestosteronemia was considered as serum total testosterone value of < 3 ng/mL, and hyperprolactinemia was considered as serum prolactin level of > 18 ng/mL. Serum hormone levels and the incidence of hormonal abnormalities were compared between the two groups. In addition, risk factors for hormonal abnormalities were investigated. There were no significant differences in the mean serum FSH (p = 0.212), LH (p = 0.623), testosterone (p = 0.332) and prolactin values (p = 0.351) between the men with and without erectile dysfunction. Hypotestosteronemia was detected in 29 (11%) of the erectile dysfunction group and in 2 (3.7%) of the control group, revealing no significant difference (p = 0.104). Hyperprolactinemia was detected in 25 (9.5%) of the erectile dysfunction group and in 2 (3.7%) of the control group, revealing no significant difference (p = 0.171). To investigate risk factors that might predict hormonal pathologies, there were no significant differences in the patient age, duration of the sexual dysfunction, smoking history and duration, the presence of chronic disease and the type of erectile dysfunction. Our findings suggest that hormonal measurement should not be routinely performed in the initial evaluation of men presenting with erectile dysfunction, and may be necessary based only on the findings obtained with a careful history and physical examination.

Maternal reproductive hormone levels after repeated ACTH application to pregnant gilts

Prenatal stress has been seen as a reason for reproductive failures in pig offspring mostly originated or mediated by changed maternal functions. In pregnant gilts, three experiments (EXP I–III) were conducted to characterize the effects of repeated ACTH on maternal cortisol concentrations (EXP I) and on the secretion of maternal reproductive hormones (LH, progesterone, estrone sulfate; EXP II+III). Exogenous ACTH was given six times every alternate day beginning either on day 49 (EXP I+II) or day 28 (EXP III) of pregnancy. As a result of treatment, elevated cortisol levels were observed for more than 6 h (EXP I). Plasma concentrations of LH were at low basal level (0.1–0.2 ng/ml), but showed a pulsatory release pattern both during first and second trimester of pregnancy. The number of LH pulses/6 h (L.S.M.±S.E.) of saline treated controls increased with ongoing pregnancy (1.4±0.1 versus 2.0±0.2 in EXP III and EXP II, respectively). After ACTH treatment the number of LH pulses did not differ between the two gestational stages (1.3±0.2 and 1.4±0.2 in EXP III and EXP II, respectively). However, differences ( P<0.05) were obtained comparing the LH pulse number of ACTH and saline treated sows during the second trimester of pregnancy. Moreover, areas under the curve (AUC) of each LH pulse and of all LH values over the baseline were significantly reduced by treatment. The levels of progesterone increased ( P<0.05) for 150–170 min after each ACTH application both in EXP II and EXP III. The concentrations of 17α-hydroxy-progesterone revealed likewise a significant elevation after each ACTH injection. Throughout EXP III, estrone sulfate concentrations were found to decrease (from 2.8–16.9 ng/ml on day 28 to 0.02–0.04 ng/ml on day 38) but without differences between ACTH-and saline-treated gilts. Further data of EXP II and EXP III, e.g. number of piglets born alive, confirmed the absence of detrimental treatment effects. Thus, repeated ACTH administration with subsequent release of cortisol is able to influence the release pattern of maternal reproductive hormones. However, these findings demonstrate that stress-related effects are dependent on the stage of pregnancy. The detected changes may affect feto–maternal interactions and, as a result, fetal reproductive development.

FSH and LH responses to GnRH after ovariectomy in postmenopausal women.

Whether the postmenopausal ovary is still playing a role in the control of gonadotrophin secretion in response to GnRH has not been investigated. The aim of the present study was to test this hypothesis by examining changes in basal and GnRH-induced gonadotrophin secretion in postmenopausal women after bilateral ovariectomy. The responses of LH and FSH to GnRH [10 microg intravenously (i.v.)] were investigated in postmenopausal women from 2 days before to 8 days after total abdominal hysterectomy plus bilateral ovariectomy. Nine postmenopausal women aged 52-67 years and between 5 and 15 years after menopause. In all cases the ovaries were histologically normal. Pituitary responses to GnRH were calculated every 12-24 h as the net increases in LH (DeltaLH) and FSH (DeltaFSH) at 30 min above the basal values. Basal values of oestradiol (E2) and testosterone were also measured. Basal values of FSH showed a significant decrease on postoperative days 2 (P < 0.01) and 8 (P = 0.03) as compared to day 0, while at the same time points after the operation LH values were marginally lower than on day 2 (P = 0.05). Serum E2 values showed a gradual increase up to postoperative day 1 (P = 0.04) and a gradual decline thereafter. Basal testosterone concentrations decreased gradually and significantly after ovariectomy and were significantly lower on day 8 than on day 0 (P < 0.01). DeltaFSH and DeltaLH responses to GnRH did not change significantly with time. A temporary increase at 12 h after the operation was not significant. These results demonstrate for the first time that the removal of the ovaries in postmenopausal women does not affect GnRH-induced gonadotrophin secretion in the short term. It is suggested that the postmenopausal ovary is not a dominant regulator of hypothalamic-pituitary interactions.

Expression of transcription factors in endometrium during natural cycles.

The sex steroid control of the endometrial cycle is mediated by transcription factors, four of which are the estrogen and progesterone receptors, c-jun and c-fos, all expressed by the endometrium. The aim of this study was to analyze the distribution of the transcription factors in the different endometrial compartments during natural cycles. We studied 53 reproductively-normal women, of whom 26 were in the proliferative phase and 27 in the secretory phase. An endometrial biopsy was performed and serum values of LH, FSH, estradiol, and progesterone were determined. We studied the expression of transcription factors using monoclonal antibodies. A correlation between estrogen receptor and c-jun and c-fos expression was observed in stroma and epithelia, and progesterone receptor expression correlated with c-jun expression in epithelia. C-jun and c-fos presented greater expression in the proliferative phase than in the secretory phase, in the stroma and in both epithelia. No relation was found between estradiol serum levels and any transcription factor, but progesterone serum levels correlated significantly with most such factors. The two proto-oncogenes could play a decisive role in regulating the endometrial cycle; they could mediate the effects induced by sex steroid, and could be related to other transcription factors.

Effect of human chorionic gonadotropin on luteal luteinizing hormone concentrations in natural cycles

Effect of human chorionic gonadotropin on luteal luteinizing hormone concentrations in natural cycles

Middle-aged men secrete less testosterone at night than young healthy men.

Aging men largely maintain their testicular androgen production. Cross-sectional studies have demonstrated that after the age of 40 yr a 0.2-2% annual decline is observed in morning total testosterone. In elderly males, the coordinate release of LH and testosterone became asynchronous despite normal serum levels of these hormones. The aim of this study was to test the reproductive hormone rhythm at night in middle-aged men. We studied seven healthy middle-aged (46.6 +/- 6.7 yr) and six healthy young (23.9 +/- 2.4 yr) men by determining their serum levels of LH and testosterone levels every 15 min from 1900-0700 h with simultaneous sleep recordings. The nocturnal rise in testosterone occurred earlier in young men (2235 +/- 0022 h) and at 2331 +/- 0057 h in middle-aged men (P < 0.04). In young men, the mean testosterone level at night (5.0 +/- 1.3 ng/ml; 17.4 +/- 4.4 nmol/liter) and the integrated nocturnal secretion [area under the curve (AUC); 60.6 +/- 8.9 ng/ml.h; 210 +/- 31 nmol/liter.h] were significantly higher compared with the values (3.6 +/- 1.1 and 31.1 +/- 7.2 ng/ml.h; 12.6 +/- 3.8 and 108 +/- 24.8 nmol/liter.h, respectively) observed in middle-aged men (P < 0.04 and P < 0.01, respectively). The mean (3.5 +/- 0.3 mIU/ml; 3.5 +/- 0.3 IU/liter) and AUC (43.4 +/- 8.3 mIU/ml.h; 43.4 +/- 8.3 IU/liter.h) LH values in middle-aged men were significantly higher than the values observed in young men (2.0 +/- 0.7 and 30.8 +/- 6.1 mIU/ml.h; 2.0 +/- 0.7 and 30.8 +/- 6.1 IU/liter.h; P < 0.05 and P < 0.01, respectively). Young men had significantly more testosterone pulses at night (6.7 +/- 1.6/12 vs. 3.8 +/- 1.1/12 h in middle-aged men; P < 0.005) of shorter interpulse interval (88.5 +/- 23.6 vs. 137.4 +/- 46.4 min; P < 0.02). LH pulse characteristics and sleep quality were similar in both groups. However, the first rapid eye movement (REM) sleep episode occurred earlier in middle-aged men (2303 +/- 0034 h) vs. young men (0010 +/- 0054 h; P < 0.04). As a consequence, the testosterone rise antedated the first REM episode by 90 min in young men. The link between testosterone rise and REM sleep episode was not observed in middle-aged men. Linear regression analysis revealed that the LH AUC was significantly related to age (P < 0.02). Analysis of covariance revealed that the two groups differed significantly in testosterone AUC (P < 0.04). Comparison of LH and testosterone concentrations showed significant and positive cross-correlations between LH and testosterone only in young men, with the testosterone rise lagging 60 min after the rise in LH. Our findings suggest that in middle-aged men, less pulsatile testosterone and more LH are secreted at night than in young men, with disruption of the association between testosterone rhythm and REM sleep. The decline in nocturnal testosterone secretion appears to involve a combination of testicular and pituitary hypogonadism.

Clinical and endocrine follow-up of patients after testicular sperm extraction

ObjectiveTo evaluate the risk of testicular damage from testicular biopsies that are carried out for testicular sperm extraction (TESE) in infertile men. DesignProspective controlled clinical study. SettingAcademic hospital. Patient(s)Forty infertile males with azoospermia. Intervention(s)Examination of the clinical, endocrine, biochemical, and sonographic data in average after 18 months after TESE was performed. Main outcome measure(s)Measurements before and after TESE: hormone values, testicular size, morphologic characteristics, and power Doppler after scrotal sonography. Result(s)Comparison of preoperative and postoperative values of basal testosterone, FSH, LH, and estradiol levels did not reveal any differences. Twelve of 26 patients had subnormal testosterone values before TESE; 14 of 39 patients had subnormal levels afterward. Postoperative sonographic measurements showed no significant difference of the testicular volume as compared with the preoperative values. Results of power Doppler sonography revealed pathological conditions (n = 5) in patients with former iliacal or testicular operations. Conclusion(s)Endocrine testicular function and testicular size were not impaired after testicular biopsy when compared with preoperative data. However, patients with nonobstructive azoospermia seem to be at risk for androgen deficiency due to primary testicular failure after repeated testicular biopsies.

A pilot study of the efficacy of intracytoplasmic sperm injection in a natural cycle

A pilot study of the efficacy of intracytoplasmic sperm injection in a natural cycle

The impact of LH serum concentration on the clinical outcome of IVF cycles in patients receiving two regimens of clomiphene citrate/gonadotrophin/0.25 mg cetrorelix

Clomiphene citrate treatment with the association of gonadotrophins and the GnRH antagonist cetrorelix 0.25mg was analysed in two different stimulation protocols for IVF. In protocol I, 18 patients were sequentially stimulated with clomiphene citrate and gonadotrophins. In protocol II, 28 patients started the gonadotrophin injections during the clomiphene citrate administration. LH values significantly dropped after the first 0.25 mg cetrorelix injection in both protocols. A total of 22% and 7% of cycles were cancelled in protocols I and II, respectively, because of poor follicular development. The clinical pregnancy rate following embryo transfer was 18.1% in protocol I and 29.1% in protocol II. In two (11.1%) cycles stimulated according to protocol I and in eight (28.5%) cycles from protocol II, premature LH surges occurred. In patients with premature LH surge, significantly fewer metaphase II oocytes were obtained. The clinical pregnancy rate following embryo transfer was 12.5% in patients with surge compared with 29.6% in patients without. LH values were lower before HCG injection in patients who achieved pregnancy in the study cycle. In conclusion, sequential clomiphene citrate and gonadotrophin administration is not recommended for clomiphene citrate/gonadotrophin/cetrorelix 0.25 cycles. Cetrorelix 0.25 mg/day was associated with a high incidence of premature LH surges and premature LH surges were associated with an adverse cycle outcome.

Effect of ovarian stimulation with recombinant follicle-stimulating hormone, gonadotropin releasing hormone antagonists, and human chorionic gonadotropin on endometrial maturation on the day of oocyte pick-up

Objective: To assess the effect of ovarian stimulation with recombinant FSH, GnRH antagonists, and hCG on endometrial maturation on the day of oocyte pick-up. Design: Prospective study. Setting: Tertiary referral center. Patient(s): Fifty-five women undergoing controlled ovarian hyperstimulation for IVF/intracytoplasmic sperm injection (ICSI). Intervention(s): [1] Ovarian stimulation with recombinant FSH, starting on day 2 of the cycle and GnRH antagonist, starting after a median of 6 days of recombinant FSH stimulation (range, 5–12 days); [2] hCG administration for ovulation induction; and [3] aspirational biopsy of endometrium at oocyte pick-up. Main Outcome Measure(s): Endometrial histology at oocyte pick-up by Noyes criteria. Result(s): Advancement of endometrial maturation (2.5 ± 0.1 days) as compared to the expected chronological date was observed in all antagonist cycles at oocyte retrieval. Endometrial advancement at oocyte pick-up increased in line with values of LH at initiation of stimulation and the duration of recombinant FSH treatment before the antagonist was started. Conclusion(s): The higher the values of LH at initiation of stimulation and the longer the duration of recombinant FSH treatment before the antagonist is started, the more advanced the endometrial maturation at oocyte pick-up.

Mechanisms linking under-nutrition and ovarian function in beef heifers

Prolonged reduction in energy intake in beef heifers has been reported to suppress ovulation but the mechanisms involved are poorly understood. The objective of this study was to examine whether changes in the pattern of LH secretion following each of three different tests predicted the functional state of the hypothalamo–pituitary–ovarian (H–P–O) axis. Test 1 examined the ratio of LH secretion during the 1 h before and 2 h after naloxone (NAL) administration. The other two tests assessed the LH surge following an exogenous oestradiol positive feedback signal (Test 2) or exogenous progesterone priming (Test 3). In phases 1 and 3, each of 8 weeks duration, the heifers were fed 100% of their maintenance energy requirements. In phase 2, of 9 weeks duration, they were fed 50% of their maintenance energy requirements. Oestrus was induced in all heifers by PG administration at the start of the experiment. Heifers were administered a naloxone challenge of 50, 100, 200 or 400 mg naloxone hydrochloride i.v. (one dose per heifer) during the mid-luteal period of phase 1 and all four naloxone treated heifers received 400 mg naloxone hydrochloride at the end of phases 2 and 3. Doses of 10, 20 or 40 mg oestradiol benzoate (EB) i.m. were each administered to two of the remaining heifers during the mid-luteal period of phase 1. One heifer on each dose of oestradiol benzoate in phase 1 had the same dose administered at the end of phases 2 and 3. The progesterone challenge was administered to three heifers by insertion of a PRID for 12 days starting in the middle of phase 2. In Test 1, the ratio of LH secretion before and after naloxone administration in phase 1 was 1:1 (50 mg), 1:4 (100 mg), 1:4 (200 mg) and 1:9 (400 mg) (50 mg versus 100 mg and 100 mg versus 200 mg doses, P<0.05); 50 mg versus 400 mg doses, P<0.001). In phase 2, this ratio was 1:1 and there was no response to 400 mg dose of naloxone in any of the four heifers. In phase 3, the ratio depended on the ovarian activity in the heifer and ranged from 1:1 to 1:4 ( P<0.05). In Test 3, a positive oestradiol feedback signal was detected in cyclic heifers in phases 1–3 but not in the acyclic heifer in phase 2. Heifers challenge with exogenous progesterone did not have oestradiol or LH values above threshold levels. We conclude that all three tests successfully predicted the functional state of the hypothalamo–pituitary–ovarian axis. In nutritionally undernourished beef heifers onset of ovarian acyclicity is either preceded or accompanied by the loss of a positive feedback signal (Test 2) and progesterone priming ability (Test 3), and that a plasma LH ratio of ≥1:2 following naloxone challenge (Test 1) is a sign of recovery of the functional state of the hypothalamo–pituitary–ovarian axis.

Effects of long term feeding of Quillaja saponins on sex ratio, muscle and serum cholesterol and LH levels in Nile tilapia ( Oreochromis niloticus (L.))

Seventeen-day-old Nile tilapia fry were fed a standard diet (C) or diets containing 50–700 mg kg −1 Quillaja saponin (QS) extract (groups S50, S150, S300, S500 and S700). After the first 8 weeks, 30 randomly selected tilapia from each of the treatments were placed in separate aquaria and fed the standard diet without saponins from then on (these were designated S50/C, S150/C, S300/C, S500/C and S700/C). The fish grew from an initial average weight of approximately 30 mg to a final average weight of 79 g during the 6-month feeding period. The difference between the average weight of C-fed tilapia and the treatment with the highest average weight after 6 months was 53.5%. The sex ratio of tilapia in the saponin-fed groups deviated from the normal 50:50 male:female ratio, with the S700 group showing a significantly higher number of males. Quillaja saponin stimulated LH release from dispersed tilapia pituitary cells in vitro. This effect was abolished in the presence of dilute calf serum. Serum LH values did not show any diet-dependent trend in either male or female tilapia in vivo. In both continuously saponin-fed and only-initially saponin-fed groups, the average serum (but not muscle) cholesterol levels in males showed an increasing trend ( R 2 values of 0.62 and 0.69) with increasing dietary saponin level. It was concluded that dietary QS has the potential to change the sex-ratio in favour of males. More investigations are required to determine the mechanism of action and the optimum dietary level of QS for maximum effects.

The influence of pH on phosphatidylcholine monolayer at the air/aqueous solution interface

The measurements of the interfacial tension at the air/aqueous subphase interface as the function of pH were performed. The interfacial tension of the air–aqueous subphase interface was divided into contributions of individuals. A simple model of the influence of pH on the phosphatidylcholine monolayer at the air/hydrophobic chains of phosphatidylcholine is presented. The contributions of additive phosphatidylcholine forms (both interfacial tension values and molecular area values) depend on pH. The interfacial tension values and the molecular areas values for LH +, LOH − forms of phosphatidylcholine were calculated. The assumed model was verified experimentally.

Low birth weight for gestational age and subsequent male gonadal function

Objective: To verify whether a reduced birth weight for gestational age was associated with a testicular dysfunction in postpubertal boys. Study design: Boys born small for gestational age (SGA) (n = 25) were compared to 24 born with an appropriate weight. All subjects were postpubertal (mean age 17.5 ± 1.3 and 17.6 ± 2.0 years, respectively). The following clinical and endocrinologic variables were evaluated: final height, target height, body mass index, testicular volume, follicle-stimulating hormone, luteinizing hormone, testosterone, and inhibin B. Results: The SGA group had reduced testicular size (16.3 ± 2.7 mL vs 22.8 ± 3.2 mL; P <.0001) with a lower testosterone level (3.76 ± 1.35 ng/mL vs 4.77 ± 1.55 ng/mL; P <.05) and a higher LH value (4.41 ± 1.61 IU/L vs 3.44 ± 1.29 IU/L; P <.05). Among the SGA group, 54% had a mean testicular volume >2 SD below the control mean (ie, <16 mL) and in these subjects, the inhibin B level was low (143 ± 46 pg/mL vs 229 ± 76 pg/mL; P <.0001). SGA patients with smaller testes had lower final height relative to target height(P <.05 vs patients with larger testes) and for the SGA group, inhibin B correlated with testicular size (P <.0001). Positive correlations also were found between the reduction of final height relative to target height and testicular volume (P <.005) and inhibin B values (P <.05). Conclusions: SGA subjects have pituitary-gonadal axis function that tends toward hypogonadism. There is a disruption of the exocrine function in subjects with smaller testicular size who failed to show a complete height catch-up growth. This study supports a link between low birth weight and lower fertility in adult males. (J Pediatr 2002;141:376-80)