Publications by authors named "Bennink H"

Objective: The effects of estetrol (E4), a natural fetal estrogen, combined with drospirenone (DRSP) were evaluated on plasma levels of sex hormone-binding globulin (SHBG), angiotensinogen and 12 hemostasis markers.

Study Design: Combinations of 3 mg DRSP with 5 or 10 mg E4 were compared with YAZ® (20 mcg ethinyl estradiol and 3 mg DRSP; EE/DRSP) in parallel groups of 15-18 healthy young women. Main outcome was the relative change from pretreatment to the end (day 24±1) of the third treatment cycle.

View Article and Find Full Text PDF

Estetrol (E4) is a fetal estrogen with estrogenic effects on reproductive organs and bone in preclinical models and in postmenopausal women. However, E4 exerts antiestrogenic effects on breast cancer (BC) cell growth in vitro and in vivo. We have investigated the effect of 14 days preoperative treatment with 20mg E4 per day on tumor proliferation markers, sex steroid receptor expression and endocrine parameters in a prospective, randomized, placebo-controlled, preoperative window trial in 30 pre- and post-menopausal women with estrogen-receptor positive early BC.

View Article and Find Full Text PDF

Background: Estetrol (E4) is a pregnancy-specific estrogenic steroid hormone produced by the human fetal liver in both male and female fetuses. During pregnancy, E4 plasma values increase exponentially until parturition and decrease thereafter. The synthesis of E4 in the liver of a newborn ceases during the first weeks after birth.

View Article and Find Full Text PDF

We tested the principle of treating malignant ovarian tumors by vaccination against their ectopically expressed protein, zona pellucida glycoprotein (ZP) 3, using as the experimental model the granulosa cell tumors that develop in transgenic mice expressing the simian virus 40 T-antigen under the inhibin-α promoter (inhα/Tag). We found high ZP3 expression in granulosa cell tumors of the transgenic mice, in human surface ovarian cancer and granulosa cell lines, and in human granulosa cell tumors and their metastases. Early preventive immunization (between 2 and 5.

View Article and Find Full Text PDF

High daily doses of gonadotrophin-releasing hormone (GnRH) antagonists during the follicular phase of ovarian stimulation were associated with low implantation rates. To test if this occurred because of profound pituitary suppression, the pituitary response was suppressed with a high-dose GnRH antagonist and recombinant LH (rLH) was added back to correct the implantation rate. An open-label, randomized, controlled, prospective clinical study in 60 patients undergoing IVF was performed.

View Article and Find Full Text PDF

This paper focuses on the question whether different estrogens (E) have different qualitative pharmacodynamic effects when used by women for contraception, Hormone Replacement Therapy (HRT) or prevention of osteoporosis. In this context estrogens have been defined as the estrogen agonists estradiol (E2), estrone (E1), estriol (E3), conjugated equine estrogens (CEE), diethylstilbestrol (DES) and ethinylestradiol (EE). Selective Estrogen Receptor Modulator's (SERM's) have been excluded from this analysis primarily because of lack of comparative (clinical) data with estrogen agonists.

View Article and Find Full Text PDF

The branching pattern and geometry of coronary microvessels are of high interest to understand and model the blood flow distribution and the processes of contrast invasion, ischemic changes and repair in the heart in detail. Analysis is performed on high resolution, 3D volumes of the arterial microvasculature of entire goat hearts, which are acquired with an imaging cryomicrotome. Multi-scale vessel detection is an important step required for a detailed quantitative analysis of the coronary microvasculature.

View Article and Find Full Text PDF

The present clinical study was conducted to investigate the effectiveness of a daily dose of 40 mg mifepristone in preventing premature LH surges in women undergoing controlled ovarian hyperstimulation (COH) for in vitro fertilization and to study the effect of this antiprogestin cotreatment on endometrial receptivity. This was a prospective, open-label, randomized, exploratory study in 15 healthy volunteer oocyte donors who were randomly allocated to the experimental COH group, including mifepristone (group 1), or the control group, using a long protocol with GnRH agonists (group 2), in a ratio of 2:1, i.e.

View Article and Find Full Text PDF

Objective: Androgens and other drugs that reduce plasma concentrations of high density lipoprotein (HDL) cholesterol are often considered to be pro-atherogenic. Tibolone lowers HDL-cholesterol by 20% but the clinical significance of this effect is unknown.

Methods: In a randomized, double-blind study, 34 women received 2.

View Article and Find Full Text PDF

Objective: To assess the clinically optimal tibolone dose for the relief of climacteric complaints.

Design: A randomised, double blind, placebo-controlled trial.

Setting: Twenty-eight centres in Norway, The Netherlands, Sweden and Finland.

View Article and Find Full Text PDF

Background: NuvaRing is a combined contraceptive vaginal ring designed for 3 weeks continuous use followed by a 1 week ring-free period. The present study evaluated ovarian function in women who were instructed to either adhere to, or deviate from, the recommended regimen of use.

Methods: In this open-label, randomized study, 45 women aged between 18 and 35 years used NuvaRing for one cycle in which the ring was used according to the recommended regimen.

View Article and Find Full Text PDF

Low HDL cholesterol increases the risk of coronary heart disease. Treatment of postmenopausal women with tibolone lowers HDL cholesterol. We elucidated the consequences of this unwanted side effect in a randomized, double-blind study, where 12 women received 2.

View Article and Find Full Text PDF

Objective: To determine the effects of oral sequential hormone replacement therapy (HRT) on lipid-profile in perimenopausal and early postmenopausal women.

Methods: We performed a single-center, randomized, placebo-controlled trial. The trial was double blind with respect to 17beta-estradiol/desogestrel (17beta-E-D) and placebo and open with respect to conjugated estrogens/norgestrel (CEE-N).

View Article and Find Full Text PDF

This review examines the evidence for the effects of tibolone on bone. Tibolone is a synthetic steroid with a mixed (estrogenic-progestogenic-androgenic) hormonal profile. Data suggest a complex receptor-mediated as well as metabolic regulation of the activity of tibolone at target tissue level.

View Article and Find Full Text PDF

This paper reviews pharmacokinetic and pharmacodynamic studies with Implanon, which provides serum etonogestrel levels sufficient to inhibit ovulation within 8 h of insertion. After a peak of 813 pg/ml at 4 days, levels reach steady state (200 pg/ml) after 4-6 months and remain sufficient to prevent ovulation for 3 years. Variability is lower than with Norplant.

View Article and Find Full Text PDF

In this article, the effects of Implanon implant use on thyroid and adrenal function was compared with those of Norplant implants. In this 2-year open randomized study of 80 implant acceptors, we found that both implants may induce minimal changes in thyroid hormones and cortisol levels, possibly secondary to alterations in the respective binding globulins in the serum. These alterations in thyroid and adrenal function would have no clinical significance in healthy women.

View Article and Find Full Text PDF

Objective: To investigate a potential correlation between vaginal bleeding and oestradiol (E2) levels/endometrial morphology in early postmenopausal women using tibolone (Livial(R)).

Methods: A 2-year randomised placebo-controlled study of 94 healthy women, 1-3 years after spontaneous menopause, receiving either placebo (n=23), 1.25 mg/day (n=36) or 2.

View Article and Find Full Text PDF

An open, prospective, comparative study was done in healthy women, aged between 18 and 40 years, to study the effects of long-term etonogestrel treatment on bone mineral density (BMD). The control group used a non-hormone-medicated intrauterine device (IUD). The BMD was measured using a dual energy X-ray absorptiometry instrument.

View Article and Find Full Text PDF

A 2-year placebo-controlled, randomized, two-center prospective study was carried out to assess the effects of tibolone (Org OD14, Livial) on trabecular and cortical bone mass and bone biochemistry parameters in elderly postmenopausal women with and without previous fractures. In total, 107 subjects, 71 with fractures and 36 without fractures, were randomized to tibolone (n = 64) or placebo (n = 43). Their mean age was 63.

View Article and Find Full Text PDF

A 2-year prospective, randomized study of 60 implant users was performed to evaluate fasting serial serum apolipoprotein A-I, A-II, and B levels before insertion and every 3 months in users of two contraceptive implants releasing levonorgestrel (Norplant) and 3-ketodesogestrel/etonogestrel (Implanon) in Birmingham, United Kingdom. All changes in serum apolipoprotein concentrations, irrespective of an increase or decrease, were smaller than one standard deviation of the mean concentration at baseline and did not exceed the normal range for the laboratory, thus implying no evidence of an increased risk of coronary heart disease.

View Article and Find Full Text PDF

The objectives of this study were to evaluate the endometrial histology and cervical cytology of users of two contraceptive implants releasing etonogestrel/3-keto-desogestrel (Implanon) and levonorgestrel (Norplant) in West Midlands (UK) users. A 2-year prospective randomized design was used to study 60 implant users. Endometrial histology and cervical cytology were compared before insertion and after 12 and 24 months.

View Article and Find Full Text PDF

In this prospective randomized clinical trial, two long-term contraceptive implants were studied with respect to hemostasis and liver function in 86 healthy young women. The two implants used were Implanon, containing the progestagen etonogestrel (the biologically active metabolite of desogestrel) and Norplant, the implant containing the progestagen levonorgestrel. The results of the trial showed that both implants had similar small effects on the hemostatic system that are not suggestive of a tendency towards thrombosis.

View Article and Find Full Text PDF