Christoph Dorn

Nuclear Receptor DAX-1 Recruits Nuclear Receptor Corepressor N-CoR to Steroidogenic Factor 1

ABSTRACT The orphan nuclear receptor steroidogenic factor 1 (SF-1) is a critical developmental regulator in the urogenital ridge, because mice targeted for disruption of the SF-1 gene lack adrenal glands and gonads. SF-1 was recently shown to interact with DAX-1, another orphan receptor whose tissue distribution overlaps that of SF-1. Naturally occurring loss-of-function mutations of the DAX-1 gene cause the human disorder X-linked adrenal hypoplasia congenita (AHC), which resembles the phenotype of SF-1-deficient mice. Paradoxically, however, DAX-1 represses the transcriptional activity of SF-1, and AHC mutants of DAX-1 lose repression function. To further investigate these findings, we characterized the interaction between SF-1 and DAX-1 and found that their interaction indeed occurs through a repressive domain within the carboxy terminus of SF-1. Furthermore, we demonstrate that DAX-1 recruits the nuclear receptor corepressor N-CoR to SF-1, whereas naturally occurring AHC mutations of DAX-1 permit the SF-1–DAX-1 interaction, but markedly diminish corepressor recruitment. Finally, the interaction between DAX-1 and N-CoR shares similarities with that of the nuclear receptor RevErb and N-CoR, because the related corepressor SMRT was not efficiently recruited by DAX-1. Therefore, DAX-1 can serve as an adapter molecule that recruits nuclear receptor corepressors to DNA-bound nuclear receptors like SF-1, thereby extending the range of corepressor action.

Activation of Luteinizing Hormone β Gene by Gonadotropin-releasing Hormone Requires the Synergy of Early Growth Response-1 and Steroidogenic Factor-1

We have previously shown that early growth response (Egr) 1-deficient mice exhibit female infertility, reflecting a luteinizing hormone (LH) β deficiency. Egr-1 activates the LHβ gene in vitro through synergy with steroidogenic factor-1 (SF-1), a protein required for gonadotrope function. To test if this synergy is essential for gonadotropin-releasing hormone (GnRH) stimulation of LHβ, we examined the activity of the LHβ promoter in the gonadotrope cell line LβT2. GnRH markedly stimulated the LHβ promoter (15-fold). Mutation of either Egr-1 or SF-1 elements within the LHβ promoter attenuated this stimulation, whereas mutation of both promoter elements abrogated GnRH induction of the LHβ promoter. Furthermore, GnRH stimulated Egr-1 but not SF-1 expression in LβT2 cells. Importantly, overexpression of Egr-1 alone was sufficient to enhance LHβ expression. Although other Egr proteins are expressed in LβT2 cells and are capable of interacting with SF-1, GnRH stimulation of Egr-1 was the most robust. We also found that the nuclear receptor DAX-1, a repressor of SF-1 activity, reduced Egr-1–SF-1 synergy and diminished GnRH stimulation of the LHβ promoter. We conclude that the synergy between Egr-1 and SF-1 is essential for GnRH stimulation of the LHβ gene and plays a central role in the dynamic regulation of LHβ expression.

Endometrial receptivity in an in vitro fertilization program as assessed by spiral artery blood flow, endometrial thickness, endometrial volume, and uterine artery blood flow

OBJECTIVE To investigate the role of sonographic parameters in assessing endometrial receptivity in an in vitro fertilization (IVF) program. DESIGN Prospective clinical study. SETTING University setting. PATIENT(S) One hundred thirty-five patients in our IVF program, selected prospectively on the day of oocyte retrieval. INTERVENTION(S) Transvaginal ultrasound examination was performed before oocyte collection. MAIN OUTCOME MEASURE(S) Association between implantation rate and spiral artery blood flow (primary outcome measure) and between implantation rate and endometrial measurements as well as uterine artery blood flow (secondary outcome measures). RESULT(S) Overall implantation rate was 23.7% per cycle. Subendometrial blood flow was detected in 113 (83.7%) cases, with pregnancy occurring in 21.2%. Mean spiral artery pulsatility index values were 1.12 +/- 0.28 and 1.21 +/- 0.27 for nonconception and conception cycles, respectively. Nondetectable spiral artery blood flow was not associated with a lower implantation rate. Neither endometrial thickness nor endometrial volume was correlated with the likelihood of successful implantation. Minimum endometrial thickness and volume associated with pregnancy were 6.9 mm and 1.59 mL, respectively. CONCLUSION(S) Neither Doppler sonography of the spiral or uterine arteries nor measurement of the endometrial thickness or volume allowed a reliable prediction of subsequent IVF outcome.

Outcome of laser-assisted polar body biopsy and aneuploidy testing

Polar body biopsy and subsequent fluorescence in-situ hybridization (FISH) analysis allows detection of maternally derived chromosomal aneuploidies in human oocytes during IVF treatment. The development of a diode laser technique for the partial opening of the zona pellucida has stimulated the use of this technique to assist polar body biopsy. Laser-assisted polar body biopsy was performed in 140 IVF cycles from patients of advanced maternal age (> or =35 years). A total of 921 oocytes were treated by a laser for partial zona opening and polar body removal. FISH was performed for chromosomes 13, 16, 18, 21 and 22 and results were available for 903 oocytes (98%). In all, 443 oocytes (49.1%) were euploid and of these, 293 were fertilized. A total of 214 embryos were transferred in 120 embryo transfer cycles (1.78 per embryo transfer) resulting in 27 clinical pregnancies (22.5% per embryo transfer) with an implantation rate of 15.4%. Subsequently, five women aborted (18.5%) and 24 healthy children were born from the remaining 22 pregnancies, which gives a take home baby rate of 18.3% per transfer cycle. It is concluded that polar body biopsy using a diode laser system is as efficient as standard polar body biopsy using zona drilling.

Oocyte zona birefringence intensity is associated with embryonic implantation potential in ICSI cycles

A retrospective study recently showed that oocytes presenting with a high birefringence of the inner zona layer were more often associated with conception cycles. To further investigate these findings, a prospective study was conducted between September 2005 and September 2006 including intracytoplasmic sperm injection (ICSI) cycles presenting with at least two embryos for transfer. Using a polarization imaging system, oocytes were classified prior to ICSI treatment as having either a high zona birefringence (HZB) or a low zona birefringence (LZB) of the zona pellucida. Using zona birefringence as the only selection criterion, two fertilized oocytes, preferably derived from HZB oocytes, were selected for further culture and transfer. The required criteria were met by 135 ICSI cycles (124 patients; 34.9 +/- 4.1 years of age). Embryos for transfer were used in 20 cycles derived from HZB/HZB oocytes, in 50 cycles from HZB/LZB oocytes and in 65 from LZB/LZB oocytes. The corresponding implantation (P < 0.025), pregnancy (P < 0.005) and live birth (P < 0.025) rates were significantly different between HZB/HZB and HZB/LZB versus LZB/LZB group. Embryo development was superior in embryos derived from HZB oocytes. This study concludes that oocyte zona birefringence is a good selection criterion and a good predictive criterion for embryo implantation potential.

Effective method for in-vitro culture of cryopreserved human ovarian tissue.

It is widely accepted that it is possible to successfully cryopreserve human ovarian tissue by direct plunging into liquid nitrogen using permeable cryoprotectants only, without disaccharides. This study aimed to search for and test a new method for in-vitro culture of vitrified tissue. Ovarian biopsies were obtained during operative laparoscopy. Pieces of ovarian tissue were vitrified and warmed. After warming, tissue pieces were randomly distributed into three groups for further culture: in 2 ml of culture medium which was regularly renewed (group 1), in 30 ml of culture medium without agitation (group 2) and in 30 ml of culture medium with agitation (group 3). During the 2-week and 6-week culture, the growth of follicles within the vitrified-warmed ovarian tissue pieces was investigated. After 2 weeks of culture, mean numbers of non-degenerated follicles per mm(2) of tissue were 1.5, 1.7 and 4.5 for groups 1, 2 and 3 respectively (groups 1 and 2 versus group 3, P < 0.05). Agitation during culture of ovarian tissue is beneficial, and can be used as a prognostic tool for future warming and autotransplantation of ovarian tissue.

Serum oxytocin concentration during embryo transfer procedure

OBJECTIVE To determine the effect of the embryo transfer (ET) procedure on serum concentration of oxytocin. STUDY DESIGN Prospective clinical study of 10 women undergoing in vitro fertilization (IVF) treatment with ET in the Section of Reproductive Medicine and Endocrinology at the Department of Obstetrics and Gynecology, University of Bonn, Germany. Serial blood samples were collected in time intervals of 20 s during embryo transfer procedure and serum oxytocin concentration was measured. RESULTS In the absence of tenaculum placement, none of the procedures associated with ET led to an increase in serum oxytocin concentration. When tenaculum placement was used, it was temporally (four out of five patients) associated with an elevation in oxytocin level, which remained elevated until of the end of ET procedure. CONCLUSION Application of a cervical tenaculum during ET or possibly also during intra uterine insemination (IUI) procedure can stimulate the release of oxytocin in some patients.

Stress relief after infertility treatment--spontaneous conception, adoption and psychological counselling.

OBJECTIVE In this study, we sought to evaluate characteristics of couples with spontaneous conceptions after treatment with assisted reproductive technologies (ART). STUDY DESIGN Data from 254 couples who underwent 1127 therapy cycles between November 1987 and February 1997, were analyzed. Chi-Square (chi(2)) test and Students t-test were used. P<0.05 was considered significant. RESULTS Spontaneous pregnancies occurred in 14% of all treated couples. Psychological counselling only was performed in 21% but was observed significantly more frequently among patients without later spontaneous conception. Ten percent of all treated couples applied for adoption. The miscarriage rate was significantly higher in the group of treatment dependent pregnancies compared to the group of patients with later spontaneous conception (27% versus 9%). The spontaneous conception rate differed significantly depending on womens age and normal semen analysis. CONCLUSION Appearance of spontaneous conception after ART-procedures should be taken into account in the first patients interview. Depending on womens age and andrological parameters, treatment-success will differ. The positive impact of psychological counselling for stress relief during and after therapy should also be noted, even though a statistically significant impact could not be demonstrated in the present study. Adoption should be discussed as an alternative to overcome infertility.

Impact of reproductive history on in vitro fertilization and intracytoplasmic sperm injection outcome: evidence from the German IVF Registry ☆

OBJECTIVE To evaluate the effect of reproductive history on the outcome of different procedures in assisted reproductive technologies (ART) comparing IVF, ICSI, and cryopreserved embryo transfer (CPE). DESIGN Prospective registration of ART cycles and their outcomes. SETTING One hundred three reproductive programs in Germany. PATIENT(S) Women undergoing 174,909 ART procedures from January 1998 through December 2000. INTERVENTION(S) Data analysis of reproductive history collected by the German IVF Registry; multiple logistic regression modeling of success rates. MAIN OUTCOME MEASURE(S) Effect of type of conception and outcome of previous pregnancies, duration of infertility, females age, and type of ART on clinical pregnancy rate per retrieval. Odds ratios with 95% CIs are reported. RESULT(S) More than one previous pregnancy was negatively correlated with outcome of IVF, ICSI, or CPE. This association disappeared when female age was restricted to a maximum of 35 years. A previous pregnancy achieved by spontaneous conception had less impact on outcome of IVF, ICSI or CPE outcome than did a previous assisted conception. Previous live births and miscarriages demonstrated a statistically significant increase compared with ectopic pregnancies and induced abortions. CONCLUSION(S) Reproductive history must be considered when counseling subfertile couples. Female age, method of conception, and previous pregnancy outcome have a significant effect on IVF, ICSI, and CPE outcome.

The role of ovarian volume in an in vitro fertilization programme as assessed by 3D ultrasound.

Abstract The study was designed to investigate the role of ovarian volume, as assessed by three-dimensional (3D) sonography, in predicting conception in an in-vitro fertilization-embryo transfer (IVF-ET) programme. Transvaginal 3D sonography was performed in 152 cycles before initiation of ovarian stimulation (day 1) and on the day of oocyte retrieval. Ovarian volume showed no significant correlation with IVF outcome. On the contrary, all ovarian measurements were lower, albeit non-significantly, in the conception group. Fifteen patients (15/152, 9.9%) had a minimum unilateral ovarian volume of ≤3 mL (1 SD below the mean) on day 1 of the stimulation cycle. In this subgroup, the likelihood of conception was 6.7% (1/15) versus 21.9% (30/137) in patients with an initial minimum ovarian volume of >3 mL. This difference did not reach statistical significance. In both groups, cancellation rates due to poor ovarian response or lack of fertilization were similar. In conclusion, ovarian volumetry as assessed by three-dimensional ultrasound failed to predict conception in women undergoing IVF treatment.