L. Vankrieken

Hormonal changes induced by short-term administration of a gonadotropin-releasing hormone agonist during ovarian hyperstimulation for in vitro fertilization and their consequences for embryo development

Several regimens have been developed to administer gonadotropin-releasing hormone agonists in association with human menopausal gonadotropins (hMG) during follicular growth stimulation for in vitro fertilization. The aim of this study was to characterize hormonal changes induced by short-term administration of agonist, and to evaluate a putative impact of the flare-up effect on follicular recruitment and subsequent IVF. Eighteen highly selected patients were randomely divided in two groups. Nine patients received a short-term administration of Buserelin (Hoechst, AG, Franfurt/Main, FRG) (day 1). They were compared with 9 patients who were exposed to a long-term protocol (day 21), and 13 control patients. Agonist-induced luteinizing hormone (LH) and follicle-stimulating hormone (FSH) increase, in early follicular phase, stimulated follicular growth, shortened follicular phase, and induced a transient rise in progesterone. This was followed by a phase of reduced LH secretion associated with a significant modification of LH immunoreactivity. The short-term regimen did not improve the follicular recruitment, and appeared to reduce the oocytes fertilization rate and embryo quality when compared with prolonged administration of peptide.

Use of a gonadotropin-releasing hormone agonist during ovarian stimulation leads to significant concentrations of peptide in follicular fluids.

The penetration of a gonadotropin-releasing hormone agonist (GnRH-a), Buserelin (Hoechst AG, Frankfurt, West Germany), into human follicular fluids (FF) was studied by means of a radioimmunoassay (RIA) and a bioassay. Acute nasal administration of a therapeutic dose of Buserelin (300 and 600 micrograms) before the ovum pickup for in vitro fertilization leads to significant concentrations of Buserelin in one-third of the FF. These concentrations ranged between 28 and 124 pg/ml, which represents 10% to 50% of the serum concentrations achieved in these patients. Follicular penetration of this agonist is time-dependent. Chronic administration during the follicular phase leads to low but significant concentrations of peptide 36 hours after the last inhalation. A very good correlation was observed between the RIA and the bioassay. This demonstrates the accuracy and the specificity of the RIA. In addition, it indicates that the Buserelin that reaches follicles is intact and is not the inactive product of degradation. Intranasal administration of Buserelin stopped 35 hours before ovum pickup appears to be an adequate way of minimizing the exposure of maturing oocytes to the GnRH-a.

Inhibition of ovulation by low-dose monophasic contraceptive containing gestodene.

Ovulation inhibition by the monophasic oral contraceptive containing 75 ug of gestodene and 30 ug of ethinyl estradiol was evaluated in 25 healthy volunteers for five cycles: a pretreatment cycle, three treatment cycles, and a posttreatment cycle. Serum luteinizing and follicle- stimulating hormones, estradiol, and progesterone levels were measured on days 8 through 17; progesterone was measured once, around day 21. Pelvic ultrasound examinations were performed on cycle days 8 to 17, luteinizing and follicle-stimulating hormone levels reached values on the lower limit of detection. Luteal activity was not detected in treated cycles. Follicular activity, which was reflected by estradiol levels, was mot strongly depressed during the first treated cycle. Pelvic ultrasound examinations confirmed excellent inhibition of follicular maturation. Restoration of ovarian function in the posttreatment cycle was excellent and showed a midcycle hormonal profile identical to the pretrial cycle.

Oxytocin Determination By Radioimmunoassay

A sensitive and specific radioimmunoassay method was developed for the determination of oxytocin in human serum. Serum oxytocin levels were assayed in five healthy male volunteers and four healthy non pregnant female volunteers after rapid intravenous injection of 2 U synthetic oxytocin. Peak oxytocin levels were found at 30 s after intravenous administration. The half-life (T1/2) of oxytocin was 6 min 22 s in male and 6 min 53 s in female serum.

Immunoradiometric assays of total renin and gonadotropins in serum during the menstrual cycle

The contribution of the ovary to the circulating total renin pool is linked to its secretory activity in relation with its reproductive function. In a longitudinal study of 13 normal women, total renin levels measured in serum by an immunoradiometric assay were lower in the midfollicular phase (180 +/- 59 pg/ml) than in the midluteal phase (291 +/- 100 pg/ml). Peak levels were encountered 1 day after the luteinizing hormone (LH) surge (375 +/- 97 pg/ml). Rapid circhoral fluctuations were observed in all periods of the cycle, unrelated to the LH pulses. In case of ovarian function inhibition (induced by gonadotropin-releasing hormone agonists), total renin levels were lower than in the midfollicular phase (126 +/- 56 pg/ml). Low levels also were encountered in the prepubertal period (153 +/- 89 pg/ml). Very high levels (17,600 +/- 11,400 pg/ml) were found in follicular fluids from stimulated cycles. These results show that circulating total renin levels follow a complex pattern in which LH, but possibly also follicle-stimulating hormone and gonadal steroid hormones (estradiol and progesterone), may play a role.

Characterization of ritodrine radioimmunoassay. Standard curves, cross-reactions and serum levels in women.

A sensitive and specific radioimmunoassay method was developed for the determination of ritodrine in human serum. Cross-reactions with four other Β-sympathomimetic drugs, various peptides, and st

Longitudinal follow-up of breast cancer patients with the tumor markers CA 549 and CA 15.3.

In order to verify the efficiency of the tumor markers CA 15.3 and CA 549 in the follow-up of breast cancer patients, it was necessary first to check the cutoff levels of each tumor marker in women with an increased age-related risk, but with no evidence of disease. From 132 serum samples in this age group, we confirmed the CA 549 cutoff level of 12.1 U/ml. However, the cutoff of CA 15.3 was 34 U/ml, which is higher than previously reported in the literature. Fifty-two breast cancer patients with or without metastases at the time of entry into the study were followed for 2 to 3 years with both tumor markers. The sensitivity, specificity and the test efficiency for the presence of metastases were analyzed with each tumor marker. Taking into account the different cutoff levels, we concluded that both tumor markers can be used independently to follow the clinical situation of patients. In several cases an increase in both tumor markers was observed before a clinical diagnosis of metastases could be made. Combination of these two tumor markers gave no more significant information about the patients clinical situation than each tumor marker alone.