Incidence of sex chromosome aneuploidy in a prenatal population: 27-year longitudinal study in Northern Italy.

OBJECTIVES: The availability of cell-free (cf) DNA as a prenatal screening tool affords an opportunity for non-invasive identification of sex chromosome aneuploidy (SCA). The aims of this longitudinal study were to investigate the evolution and frequency of both invasive prenatal diagnostic testing, using amniocentesis and chorionic villus sampling (CVS), and the detection of SCA in cfDNA samples from a large unselected cohort in Northern Italy. METHODS: The results of genetic testing from CVS and amniotic fluid samples received from public and private centers in Italy from 1995 to 2021 were collected. Chromosomal analysis was performed by routine Q-banding karyotype. Regression analyses and descriptive statistics were used to determine population data trends regarding the frequency of prenatal diagnostic testing and the identification of SCA, and these were compared with the changes in indication for prenatal diagnostic tests and available screening options. RESULTS: Over a period of 27 years, there were 13 939 526 recorded births and 231 227 invasive procedures were performed, resulting in the prenatal diagnosis of 933 SCAs. After the commercial introduction of cfDNA use in 2015, the frequency of invasive procedures decreased significantly (P = 0.03), while the frequency of prenatal SCA detection increased significantly (P = 0.007). Between 2016 and 2021, a high-risk cfDNA result was the indication for 31.4% of detected sex chromosome trisomies, second only to advanced maternal age. CONCLUSIONS: Our findings suggest that the inclusion of SCA in prenatal cfDNA screening tests can increase the prenatal diagnosis of affected individuals. As the benefits of early ascertainment are increasingly recognized, it is essential that healthcare providers are equipped with comprehensive and evidence-based information regarding the associated phenotypic differences and the availability of targeted effective interventions to improve neurodevelopmental and health outcomes for affected individuals. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Genetic characterization of the zoonotic parasite Ancylostoma caninum in the central and eastern United States.

Ancylostoma caninum is the most common nematode parasite of dogs in the United States. The present study aimed to describe the molecular epidemiology of A. caninum isolates from the central and eastern states of the United States using the partial mitochondrial cytochrome oxidase (cox1) gene and to compare them with those reported globally. We isolated eggs from faecal samples of dogs and characterized each isolate based on cox1 sequences. A total of 60 samples originating from Kansas, Iowa, New York, Florida and Massachusetts were included. 25 haplotypes were identified in the United States dataset with high haplotype diversity (0.904). Sequence data were compared to sequences from other world regions available in GenBank. Global haplotype analysis demonstrated 35 haplotypes with a haplotype diversity of 0.931. Phylogenetic and network analysis provide evidence for the existence of moderate geographical structuring of A. caninum haplotypes. Our results provide an updated summary of A. caninum haplotypes and data for neutral genetic markers with utility for tracking hookworm populations. Sequences have been deposited in GenBank (ON980650-ON980674). Further studies of isolates from other regions are essential to understand the genetic diversity of this parasite.

Recurrent excitation in neocortical circuits.

The majority of synapses in the mammalian cortex originate from cortical neurons. Indeed, the largest input to cortical cells comes from neighboring excitatory cells. However, most models of cortical development and processing do not reflect the anatomy and physiology of feedback excitation and are restricted to serial feedforward excitation. This report describes how populations of neurons in cat visual cortex can use excitatory feedback, characterized as an effective "network conductance", to amplify their feedforward input signals and demonstrates how neuronal discharge can be kept proportional to stimulus strength despite strong, recurrent connections that threaten to cause runaway excitation. These principles are incorporated into models of cortical direction and orientation selectivity that emphasize the basic design principles of cortical architectures.

CD4-independent binding of SIV gp120 to rhesus CCR5.

CCR5 and CD4 are coreceptors for immunodeficiency virus entry into target cells. The gp120 envelope glycoprotein from human immunodeficiency virus strain HIV-1(YU2) bound human CCR5 (CCR5hu) or rhesus macaque CCR5 (CCR5rh) only in the presence of CD4. The gp120 from simian immunodeficiency virus strain SIVmac239 bound CCR5rh without CD4, but CCR5hu remained CD4-dependent. The CD4-independent binding of SIVmac239 gp120 depended on a single amino acid, Asp13, in the CCR5rh amino-terminus. Thus, CCR5-binding moieties on the immunodeficiency virus envelope glycoprotein can be generated by interaction with CD4 or by direct interaction with the CCR5 amino-terminus. These results may have implications for the evolution of receptor use among lentiviruses as well as utility in the development of effective intervention.

Mutations disrupting neuronal connectivity in the Drosophila visual system.

The photoreceptor neurons (R cells) of the Drosophila compound eye elaborate a precise array of neuronal connections in the brain. These projections exhibit target specificity and create topographic maps (retinotopy). We have screened histologically for mutations disrupting R cell connectivity in developing tissue. Eighty mutations were isolated from over 6000 ethylmethane sulfonate-mutagenized lines. Characterization of these mutations included genetic mosaic analysis to determine whether the gene is required in the retina or in the optic ganglia. Most mutations were found to affect connectivity indirectly by disrupting development more generally in the eye or brain. Genes were identified as candidates for playing direct roles in R cell connectivity by affecting axonal outgrowth (eddy), target recognition (limbo and nonstop), and retinotopy (limbo).

Does bouton morphology optimize axon length?

The total length of cortical axons could be reduced if the parent axons maintained straight trajectories and simply connected to dendritic shafts via spine-like terminaux boutons and to dendritic spines via bead-like en passant boutons. Cortical axons from cat area 17 were reconstructed from serial electron micrographs and their bouton morphology was correlated with their synaptic targets. En passant or terminaux boutons did not differ in the proportion of synapses they formed with dendritic spines and shafts, and thus, the two morphological variants of synaptic bouton do not contribute directly to optimizing axon length.

Dendritic asymmetry cannot account for directional responses of neurons in visual cortex.

A simple model was proposed to account for the direction selectivity of neurons in the primary visual cortex, area V1. In this model, the temporal asymmetries in the summation of inhibition and excitation that produce directionality were generated by structural asymmetries in the tangential organization of the basal dendritic tree of cortical neurons. We reconstructed dendritic trees of neurons with known direction preferences and found no correlation between the small biases of a neuron's dendritic morphology and its direction preference. Detailed simulations indicated that even when the electrotonic asymmetries in the dendrites were extreme, as in cortical Meynert cells, the biophysical properties of single neurons could contribute only partially to the directionality of cortical neurons.

Rapamycin inhibits cell motility by suppression of mTOR-mediated S6K1 and 4E-BP1 pathways.

Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), inhibits tumor cell motility. However, the underlying mechanism is poorly understood. Here, we show that rapamycin inhibited type I insulin-like growth factor (IGF-I)-stimulated motility of a panel of cell lines. Expression of a rapamycin-resistant mutant of mTOR (mTORrr) prevented rapamycin inhibition of cell motility. However, cells expressing a kinase-dead mTORrr remained sensitive to rapamycin. Downregulation of raptor or rictor by RNA interference (RNAi) decreased cell motility. However, only downregulation of raptor mimicked the effect of rapamycin, inhibiting phosphorylation of S6 kinase 1 (S6K1) and 4E-BP1. Cells infected with an adenovirus expressing constitutively active and rapamycin-resistant mutant of p70 S6K1, but not with an adenovirus expressing wild-type S6K1, or a control virus, conferred to resistance to rapamycin. Further, IGF-I failed to stimulate motility of the cells, in which S6K1 was downregulated by RNAi. Moreover, downregulation of eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) by RNAi-attenuated rapamycin inhibition of cell motility. In contrast, expression of constitutively active 4E-BP1 dramatically inhibited IGF-I-stimulated cell motility. The results indicate that both S6K1 and 4E-BP1 pathways, regulated by TORC1, are required for cell motility. Rapamycin inhibits IGF-I-stimulated cell motility, through suppression of both S6K1 and 4E-BP1/eIF4E-signaling pathways, as a consequence of inhibition of mTOR kinase activity.

Prostacyclin, atherothrombosis, and cardiovascular disease.

Prostacyclin (PGI(2)) is a major product of COX-2 catalyzed metabolism of arachidonic acid in the endothelium. Recent studies have demonstrated that PGI(2) protects against atherothrombosis. The prostacyclin receptor knockout mice exhibit increased atherosclerosis, enhanced thrombosis, and enhanced proliferative response to carotid vascular injury with increased intima to media ratios [1-3]. Moreover, the recent withdrawal of rofecoxib (Vioxx) due to increased cardiovascular events further supports the critical role of prostacyclin in inhibiting atherothrombosis in humans. Such studies have paralleled intense chemical biology studies to develop more stable prostacyclin analogues. Indeed a number of these analogues are currently being successfully used for the treatment of pulmonary hypertension. In this review we will summarize the current literature on some principles of prostacyclin analogue development, our current understanding of the receptor, and recent developments which implicate prostacyclin in atherothrombotic protection. More than 68 million Americans suffer from cardiovascular disease, which causes more deaths, disability and economic loss than any other group of diseases. Further clinical investigations of orally stable prostacyclin analogues for treatment of cardiovascular diseases other than pulmonary hypertension may now be warranted.

p70 S6 kinase is regulated by protein kinase Czeta and participates in a phosphoinositide 3-kinase-regulated signalling complex.

p70 S6 kinase (p70S6K) is an important regulator of cell proliferation. Its activation by growth factor requires phosphorylation by various inputs on multiple sites. Data accumulated thus far support a model whereby p70S6K activation requires sequential phosphorylations at proline-directed residues in the putative autoinhibitory pseudosubstrate domain, as well as threonine 389. Threonine 229, a site in the catalytic loop is phosphorylated by phosphoinositide-dependent kinase 1 (PDK-1). Experimental evidence suggests that p70S6K activation requires a phosphoinositide 3-kinase (PI3-K)-dependent signal(s). However, the intermediates between PI3-K and p70S6K remain unclear. Here, we have identified PI3-K-regulated atypical protein kinase C (PKC) isoform PKCzeta as an upstream regulator of p70S6K. In coexpression experiments, we found that a kinase-inactive PKCzeta mutant antagonized activation of p70S6K by epidermal growth factor, PDK-1, and activated Cdc42 and PI3-K. While overexpression of a constitutively active PKCzeta mutant (myristoylated PKCzeta [myr-PKCzeta]) only modestly activated p70S6K, this mutant cooperated with PDK-1 activation of p70S6K. PDK-1-induced activation of a C-terminal truncation mutant of p70S6K was also enhanced by myr-PKCzeta. Moreover, we have found that p70S6K can associate with both PDK-1 and PKCzeta in vivo in a growth factor-independent manner, while PDK-1 and PKCzeta can also associate with each other, suggesting the existence of a multimeric PI3-K signalling complex. This work provides evidence for a link between a phorbol ester-insensitive PKC isoform and p70S6K. The existence of a PI3-K-dependent signalling complex may enable efficient activation of p70S6K in cells.

Opening the grey box.

The single neurone has been the guiding light for generations of neuroscientists. Now there are signs from experimental and theoretical work on the neocortex that we are on the threshold of a revolution in which the hegemony of the single neurone will be replaced by much more circuit-oriented concepts. We consider here why traditional views of the significance of single neurones are fading in power, and consider the problem of deciding on the form of a new order.

Precursors of alpha-inhibin modulate follicle-stimulating hormone receptor binding and biological activity.

Although several forms of monomeric alpha-inhibin have been isolated from follicular fluid, no biological function has yet been ascribed to these posttranslationally processed forms of the alpha-subunit precursor protein. Moreover, previous studies of a FSH receptor binding competitor (FRBC) isolated and characterized from porcine follicular fluid (pFF) suggested certain biochemical similarities between this protein and alpha-inhibin precursors. We, therefore, investigated the hypothesis that alpha-inhibin and/or its precursors might represent autocrine and/or paracrine modulators of FSH action in the ovary, accounting for some of this FRBC activity and thereby exerting some degree of regulation over follicular maturation. Three separate sources of alpha-inhibin proteins were investigated for FRBC activity, including pFF, human FF (hFF), and a 293 cell line into which the full-length human alpha-inhibin cDNA had been stably transfected. Conditioned medium from these transfected cells contained several forms of alpha-inhibin precursors as well as mature alpha-inhibin, but no beta-subunit or intact inhibin. alpha-Inhibin proteins from all three sources, purified by a variety of methods, including immunoaffinity chromatography on an anti-alpha-inhibin column, inhibited FSH binding to both natural tissue FSH receptors as well as recombinant rat FSH receptors expressed in 293 cells. Furthermore, dimeric inhibin and activin, medium from untransfected 293 cells, and non-alpha-inhibin-containing purification fractions were inactive in either assay. In addition, purified recombinant alpha-inhibin proteins were partial in vitro FSH antagonists in a bioassay in which cAMP generation from 293 cells expressing the recombinant FSH receptor is used as an index of FSH biological activity. These same fractions of hFF containing FRBC activity did not bind to LH receptors, thereby demonstrating receptor specificity for this activity. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting with alpha-inhibin or FRBC antisera, a 57,000 mol wt protein was identified in FRBC-active fractions from all three sources, suggesting that the active moiety was the full-length alpha-inhibin precursor protein or a large mol wt fragment, but not mature alpha-inhibin. Lastly, all FRBC activity from all three sources was extracted by an alpha-inhibin immunoaffinity column and was recoverable upon elution. These results demonstrate that proteins derived from the alpha-inhibin precursor modulate FSH binding to its receptor as well as its biological activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Neuroendocrine abnormalities in hypothalamic amenorrhea: spectrum, stability, and response to neurotransmitter modulation.

UNLABELLED: To characterize the neuroendocrine patterns of abnormal GnRH secretion in hypothalamic amenorrhea (HA), 49 women with primary and secondary HA underwent frequent sampling of LH in a total of 72 baseline studies over 12-24 h. A subset of women participated in more than one study to address 1) the variability of LH pulse patterns over time; and 2) the impact of modulating opioid, dopaminergic, and adrenergic tone on LH secretory patterns. The frequency and amplitude of LH secretion was compared with that seen in the early follicular phase (EFP) of normally cycling women. The spectrum of abnormalities of LH pulses was 8% apulsatile, 27% low frequency/low amplitude, 8% low amplitude/normal frequency, 43% low frequency/normal amplitude, 14% normal frequency/normal amplitude. Of patients studied overnight, 45% demonstrated a pubertal pattern of augmented LH secretion during sleep. Of patients studied repeatedly, 75% demonstrated at least 2 different patterns of LH secretion, and 33% reverted at least once to a normal pattern of secretion. An increase in LH pulse frequency was seen in 12 of 15 subjects in response to naloxone (opioid receptor antagonist). Clonidine (alpha-2 adrenergic agonist) was associated with a decrease in mean LH in 3 of 3 subjects. An increase in LH pulse frequency was seen in 4 of 8 subjects in response to metoclopramide (dopamine receptor antagonist), but the response was not statistically significant. Baseline abnormalities in LH secretion did not appear to influence response to neurotransmitter modulation. CONCLUSIONS: 1) HA represents a spectrum of disordered GnRH secretion that can vary over time; 2) LH pulse patterns at baseline do not appear to influence the ability to respond to neurotransmitter modulation; 3) Opioid and adrenergic tone appear to influence the hypothalamic GnRH pulse generator in some individuals with HA.

Comparison of exogenous gonadotropins and pulsatile gonadotropin-releasing hormone for induction of ovulation in hypogonadotropic amenorrhea.

To compare the efficacy and safety of ovulation induction with exogenous gonadotropins vs. pulsatile GnRH in patients with hypogonadotropic amenorrhea, results from 30 patients in 111 cycles of gonadotropins and 41 patients in 118 cycles of pulsatile GnRH were analyzed retrospectively. Exogenous gonadotropins were administered using an individually adjusted protocol, using a starting dose of 150 IU. Pulsatile GnRH was delivered iv at a physiological frequency based upon our normative data. The doses administered ranged from 75-250 ng/kg. Preovulatory serum estradiol (E2) and luteal phase progesterone (P) levels were compared to those in normal cycling women (n = 87). The mean body mass index, age, and baseline gonadotropin levels were similar in the two groups. Overall ovulatory rates and conception rates per cycle and per patient were not significantly different between the two groups. However, the cumulative chance of conception after six cycles of treatment by life table analysis appeared to be higher with pulsatile GnRH treatment (96%) than with exogenous gonadotropins (72%). The risk of multiple gestation was also higher with exogenous gonadotropins (14.8% vs. 8.3%), although this was not statistically significant. All higher order multiple gestations (triplets or more) occurred in the gonadotropin-treated group. More than two dominant follicles were seen on ultrasound in 47.6% of gonadotropin-treated cycles compared to 18.9% of cycles with pulsatile GnRH treatment (P < 0.01). Three or more follicles were seen in 16.6% of the gonadotropin cycles compared to 5.4% with pulsatile GnRH (P < 0.05). No case of severe ovarian hyperstimulation was observed in either group, although the mean luteal phase ovarian size was significantly higher in the gonadotropin group (P < 0.05). Mean peak preovulatory E2 levels were significantly higher in the gonadotropin group (1684.5 +/- 124.4 vs. 1315.3 +/- 74.9 pmol/L; P < 0.05). The mean luteal phase P level 1 week after ovulation was significantly higher than normal in the gonadotropin group (84.9 +/- 10.8 vs. 61.1 +/- 3.2 nmol/L; P < 0.05), but was not significantly different from that in the pulsatile GnRH group (70.3 +/- 6.0 nmol/L). We conclude that pulsatile GnRH, when compared to exogenous gonadotropins, results in high rates of ovulation and conception, but a decreased risk of multiple folliculogenesis, higher order multiple gestations, and ovarian enlargement.(ABSTRACT TRUNCATED AT 400 WORDS)

Hypothalamic gonadotropin-releasing hormone secretion and follicle-stimulating hormone dynamics during the luteal-follicular transition.

To define the precise neuroendocrine characteristics of the luteal-follicular transition, 11 normal women underwent 12 frequent sampling studies at 10-min intervals for 48 h at various points during the transition from one cycle to the next. Daily blood samples captured both the preceding and subsequent LH surges, so that studies could be characterized in relation to the preceding LH peak (LH+), the subsequent LH peak (LH-), and menses (M). In the frequent sampling study, LH and FSH were measured in all samples, and estradiol (E2) and progesterone (P) were measured in 2-h pools. The frequency of pulsatile LH secretion increased 4.5-fold over an 8-day period spanning the luteal-follicular transition. This increase in LH pulse frequency was strongly related to the preceding LH peak (r = 0.82; P less than 0.00001), but was not at all related to the onset of menses. When the temporal markers (i.e. LH+, LH-, and M) were removed from the analysis, LH pulse frequency was inversely related to the log of serum P (r = 0.50; P less than 0.005), but not E2. FSH levels increased both within the individual studies (P less than 0.005) and in the group as a whole over the duration of the luteal-follicular transition. Mean FSH rose 3.5-fold compared to less than a 2-fold increase in mean LH. As with LH pulse frequency, the increase in FSH was most strongly related to the preceding LH peak, but was also significantly associated with the subsequent LH peak and the onset of menses. The relationship between FSH and the number of days from the preceding LH peak is even better fit by a second degree polynomial, which revealed an abrupt increase in LH beginning at LH+11. With the temporal markers excluded, the increase in FSH related only to LH pulse frequency (r = 0.62; P less than 0.001). FSH was not statistically related to the decreases in P or E2, which are also key variables at this stage of the menstrual cycle. We reached the following conclusions. 1) A dramatic increase in LH pulse frequency, and by inference GnRH pulse frequency, accompanies the selective rise in FSH levels during the luteal-follicular transition of the normal menstrual cycle. 2) Both the increase in GnRH pulse frequency and the rise in FSH levels during this transition are strongly related to the preceding LH peak, while the clinical marker of menses is a relatively poor indicator of these events.(ABSTRACT TRUNCATED AT 400 WORDS)

Decrease in gonadotropin-releasing hormone (GnRH) pulse frequency with aging in postmenopausal women.

UNLABELLED: Increasing evidence suggests that aging is associated with dynamic changes in the hypothalamic and pituitary components of the reproductive axis that are independent of changes in gonadal hormone secretion. This study was designed to determine the effect of age on GnRH pulse frequency in women in the absence of gonadal feedback using gonadotropin free alpha-subunit (FAS) and LH as neuroendocrine markers of endogenous GnRH secretion. All studies were performed in healthy, euthyroid postmenopausal women (PMW) during daytime hours. The impact of sampling interval and duration on assessment of pulse frequency in PMW was first examined in 10 women with a mean age of 61.6 +/- 8 yr (mean +/- SD), in whom blood was sampled every 5 min for 12 h. Each 5-min series was then reduced to simulate a 10-min series and then a 15-min series for pulse analysis, and the effect of 8 h compared with 12 h of sampling was determined. To define the changes in the frequency and amplitude of pulsatile hormone secretion with aging, 11 younger (45-55 yr) and 11 older (70-80 yr) PMW were then studied over 8 h at a 5-min sampling interval. In the initial series, the mean interpulse intervals (IPIs) for FAS were 53.8 +/- 3.6, 69.2 +/- 3.9, and 87.6 +/- 7.3 min at sampling intervals of 5, 10, and 15 min, respectively (P < 0.0005). The LH IPI also increased progressively with sampling intervals of 5, 10, and 15 min (54.4 +/- 2.5, 70.4 +/- 2.3, and 91.1 +/- 4.4 min; P < 0.0001). At the 5-min sampling interval, the calculated number of pulses/24 h was not different between a 12-h series compared with an 8-h series for either FAS or LH. In the second series of studies, the older PMW had lower gonadotropin levels (LH, 86.5 +/- 8.8 vs. 51.3 +/- 7.7 IU/L, P < 0.01; FSH, 171.6 +/- 16.9 vs. 108.2 +/- 10.5 IU/L, P < 0.005; FAS, 1021.5 +/- 147.4 vs. 425.6 +/- 89.6 ng/L, P < 0.005, in younger and older PMW, respectively) despite no differences in estrone or estradiol levels. The older PMW also demonstrated a slower FAS pulse frequency compared with their younger counterparts, as reflected in an increased FAS IPI (52.6 +/- 3.1 and 70.6 +/- 5.9 min; P < 0.002). The difference in IPIs between younger and older PMW was not statistically significant for LH (65.4 +/- 5.6 and 71.8 +/- 6.6 min for younger and older PMW, respectively). FAS pulse amplitude was decreased in older PMW compared with younger PMW (431.7 +/- 66.2 vs. 224.6 +/- 81.9 ng/L; P < 0.01), whereas the decrease in LH pulse amplitude with age was of borderline statistical significance (23.2 +/- 3.1 vs. 15.9 +/- 2.1 IU/L; P = 0.09). IN CONCLUSION: 1) the use of a 5-min sampling interval and measurement of FAS as the primary marker of GnRH pulse generator activity indicate that GnRH pulse frequency in younger PMW is faster than previously reported, but not increased over that seen in the late follicular phase and midcycle surge in women with intact ovarian function; and 2) the marked decrease in FAS pulse frequency with age provides evidence of age-related changes in the hypothalamic component of the reproductive axis that are independent of changes in gonadal function.

Potential for fertility with replacement of hypothalamic gonadotropin-releasing hormone in long term female survivors of cranial tumors.

Dysfunction of the hypothalamic-pituitary axis presenting as hypogonadotropic amenorrhea is a common sequelae of treatment for cranial tumors with surgery and/or radiation. We hypothesized that the site of the defect in this condition is hypothalamic, rather than pituitary, in the majority of patients. Nine women with acquired hypogonadotropic hypogonadism after treatment with transphenoidal pituitary surgery (n = 3), transphenoidal surgery plus conventional radiotherapy (XRT; n = 1), hypothalamic surgery plus XRT (n = 2), or XRT with or without noncentral nervous system surgery (n = 3) underwent assessment of endogenous pulsatile LH secretion and a standard GnRH test followed by iv administration of a physiological replacement regimen of exogenous GnRH. A total of 25 cycles were completed at doses of 75 or 100 ng/kg.bolus. Ovulation occurred in 78% of patients, with all ovulatory patients who desired fertility becoming pregnant. The hormonal responses in these cycles did not differ from the patterns of sex steroids and gonadotropins in normal women. The response to pulsatile GnRH was not influenced by GH deficiency or PRL abnormalities. Of the two patients who failed to ovulate, there was no evidence of folliculogenesis in one, whereas the second consistently developed follicles, but proved incapable of mounting a LH surge despite adequate preovulatory estradiol levels. Both patients had a history of pituitary radiation and surgery. There was no consistent relationship between the results of GnRH testing and the pattern of pulsatile LH secretion. However, the only patient who failed to achieve folliculogenesis was the only patient without a FSH response to GnRH testing and an apulsatile baseline study. Hypothalamic GnRH deficiency is the etiology of hypogonadism in the majority of patients after treatment with hypothalamic or pituitary surgery or cranial irradiation. Therefore, exogenous pulsatile GnRH represents a physiological replacement therapy that completely restores normal gonadotropin dynamics, resulting in ovulation and fertility.

Exaggerated free alpha-subunit levels during pulsatile gonadotropin-releasing hormone replacement in women with idiopathic hypogonadotropic hypogonadism.

The goals of this study were to determine whether women with idiopathic hypogonadotropic hypogonadism (IHH) respond to pulsatile GnRH replacement therapy with exaggerated glycoprotein free alpha-subunit (FAS) levels, as reported in GnRH-deficient men, and to determine whether this pattern is unique to congenital GnRH deficiency or is also characteristic of patients with hypogonadotropic hypogonadism caused by other factors. GnRH was administered i.v. at a physiologic frequency and dose (75-100 ng/kg.bolus) to women with IHH (n = 11; n = 6 with anosmia); acquired GnRH deficiency secondary to treatment for cranial tumors (AHH; n = 7); and secondary hypothalamic amenorrhea (HA; n = 8). Results were compared with 24 normal cycling women. Gonadotropins, sex steroids, and FAS levels were measured in samples drawn daily across induced or normal menstrual cycles in patients or normal women, respectively. Samples were drawn at the same time of day and were collected 45 min after a GnRH bolus in patients. All women ovulated in response to pulsatile GnRH. There were no differences in the patterns of LH or gonadal steroid secretion between any of the patient groups (IHH, AHH, and HA). The patterns of LH and FSH secretion in the induced patient cycles were not different from normal women, with the exception of lower midcycle FSH levels in IHH women (P < 0.002). However, the daily dynamic secretion of FAS was exaggerated in IHH (compared with AHH, HA, and normal) women (P < 0.002). The increase in FAS levels in IHH was dependent on cycle stage, with the greatest difference observed during the early (P < 0.005) and midfollicular phase (P < 0.05) and the early luteal phase (P < 0.05). There was no difference in FAS between groups during the late follicular phase, at the midcycle, or in the midluteal and late luteal phase. This exaggerated FAS response to GnRH replacement in IHH was demonstrated in repeat cycles in two patients. Conclusions are: 1) Women with IHH respond to pulsatile GnRH replacement with an exaggerated secretion of FAS, which seems to be modified by gonadal factors; 2) this exaggerated FAS response, which is similar to that seen in GnRH-deficient men, is unique to congenital GnRH deficiency, and it is not observed in patients with acquired or secondary hypogonadotropic hypogonadism, suggesting that IHH patients may be missing a factor, in addition to GnRH, which normally restrains FAS secretion; and 3) the FAS response may prove to be a useful marker to distinguish constitutional delay of puberty from congenital GnRH deficiency.

Disappearance of endogenous luteinizing hormone is prolonged in postmenopausal women.

Pituitary secretion of LH is increased after menopause, but it is not known whether changes in LH clearance also contribute to elevated serum levels. To determine whether the disappearance of endogenous LH is decreased in postmenopausal women (PMW), compared with normal cycling women, GnRH receptor blockade was used to inhibit endogenous secretion of LH and the glycoprotein free alpha-subunit (FAS), and the decline of serum levels was monitored. The NAL-GLU GnRH antagonist ([Ac-D-2Nal1,D-4ClPhe2, D-3Pal3,Arg5,D-4-p-methoxybenzoyl-2-aminobutyric acid6,D-Ala10]GnRH) was administered s.c., at doses of 5, 15, 50, and 150 microg/kg, to 15 euthyroid PMW in 21 studies. Blood was sampled every 10 min, for 4 h before and 8 h after a single sc injection of the GnRH antagonist, followed by hourly samples, ending at 20 h after injection. Results of the maximally suppressive doses (50 and 150 microg/kg) were compared with those of 24 normal cycling women in the early follicular phase and late follicular phase or early luteal phase, and 8 women at the midcycle surge (MCS), who also received these doses of the GnRH antagonist. The best fit curve describing the decay of hormone serum levels after maximal GnRH receptor blockade was determined by nonlinear regression analysis. The elimination of both LH and FAS, after GnRH receptor blockade, exhibited apparent first-order kinetics characterized by a single exponential phase. No differences were seen in percent suppression or half-lives (t1/2) of LH or FAS, between the 50- and 150-microg/kg antagonist doses, in any of the subject populations; and percent suppression of LH was similar across all groups. The t1/2 of LH was prolonged in PMW (139 +/- 35 min, mean +/- est. SD), in comparison with both the MCS (78 +/- 20 min; P < 0.0005) and other cycle stages (57 +/- 28 min; P < 0.0001). However, the disappearance of FAS was not different in PMW, compared with MCS or other cycle stages (t1/2 = 51 +/- 26, 41 +/- 12, and 41 +/- 19 min, respectively). Our conclusions were: 1) Disappearance of endogenous LH after GnRH receptor blockade is significantly prolonged in PMW, compared with the MCS or other cycle stages; 2) The disappearance of FAS is not altered in PMW, suggesting that differences in the disappearance of LH relate to LH microheterogeneity rather than systemic factors.

Use of a gonadotropin-releasing hormone antagonist as a physiologic probe in polycystic ovary syndrome: assessment of neuroendocrine and androgen dynamics.

The majority of patients with polycystic ovary syndrome (PCOS) exhibit an increase in both the frequency and amplitude of LH secretion, which is thought to contribute to the hyperandrogenism associated with this disorder. The increase in LH pulse amplitude may reflect either enhanced pituitary sensitivity to GnRH and/or an increase in hypothalamic GnRH secretion. To determine whether endogenous GnRH secretion is increased in PCOS and to document the degree and time course of androgen suppression after acute LH inhibition, the Nal-Glu GnRH antagonist was administered s.c. at 4 doses (5, 15, 50, and 150 micrograms/kg) to 11 women with PCOS. The response to GnRH receptor blockade was compared with data from regularly cycling women (n = 50) studied in the early and late follicular, and early luteal phases. The response to more prolonged GnRH receptor blockade was determined in a subset of patients, in whom 150 micrograms/kg of the GnRH antagonist was administered s.c. every 24 h for 3 days (n = 7) and continued for 7 days in 3 subjects. LH levels decreased in a dose-dependent fashion after administration of the GnRH antagonist (P < 0.0001), with a maximum percent inhibition of 83 +/- 2%. At all except the 5 micrograms/kg dose, mean LH levels remained significantly lower than baseline for up to 20 h post antagonist (P < 0.002). At all antagonist doses, both the degree and duration of LH suppression were similar in PCOS and normal women. The maximum percent inhibition of FSH was 39 +/- 2%, which was significantly less than that of LH (P < 0.001). Testosterone (T) levels fell significantly within 4 h of antagonist administration, with maximum percent inhibition of 39 +/- 3% occurring at 8 h. In the patients in whom 150 micrograms/kg of the antagonist was given for 3-7 days, no further suppression of either gonadotropins or T was noted. Our conclusions were: 1) The equivalent susceptibility of LH to submaximal GnRH receptor blockade in normal and PCOS women suggests that the elevated LH levels in PCOS are not the result of an increase in the quantity of GnRH secreted. These data imply that it is the frequency of GnRH stimulation per se and/or enhanced pituitary sensitivity to endogenous GnRH that underlie the gonadotropin abnormalities in PCOS; and 2) The rapid suppression of T with increasing GnRH antagonist dose is consistent with acute regulation of T secretion by LH.