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Biomedical subjects

C Lauritzen

Publications and source records attributed to C Lauritzen.

At least 73 records · Page 4Linked to original sources
PubMed1991

How do androgens affect episodic gonadotrophin secretion in postmenopausal women?

In the absence of any significant ovarian oestrogen secretion, as in post-menopausal women, the hypothalamic-pituitary axis may still be influenced by the androgens which continue to be produced. The episodic secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by postmenopausal women was accordingly assessed following short-term androgen antagonism induced by flutamide, a specific androgen receptor blocker. Blood samples were collected at 10-min intervals for 10 h in nine women before and during flutamide administration (750 mg/day for 6 days) for the determination of gonadotrophin and sex hormone concentrations by radioimmunoassay. On both occasions, 25 micrograms of gonadotrophin-releasing-hormone (GnRH) was injected intravenously 8 h after initiation of the blood collections. Flutamide administration decreased (P less than 0.01 or less) androgen concentrations (testosterone, androstenedione and dehydroepiandrosterone sulphate) in relation to baseline values, but did not alter oestrogen (oestrone and oestradiol) or sex-hormone-binding globulin levels. The LH and FSH pulse characteristics (frequency, amplitude, interpulse interval and transverse mean levels) determined by a cluster algorithm in the gonadotrophin secretory profiles did not differ before and during androgen blockade. By contrast, androgen antagonism increased LH (P less than 0.01) and tended to enhance FSH (P = 0.10) FSH release in response to GnRH stimulation. Hence, short-term androgen receptor blockade with flutamide did not greatly affect episodic gonadotrophin secretion. However, the combined evidence of the enhanced gonadotrophin release observed in response to GnRH stimulation and the unchanged gonadotrophin secretion during androgen antagonism suggests that alterations in the magnitude, but not the frequency, of hypothalamic GnRH release had occurred. Even in the presence of substantial serum androgen concentrations, the gonadotrophin pulse rhythm in hypogonadal women constitutes the maximal-rate GnRH-LH release pattern.

Androgens↗
PubMed1991

[Pregnancy after direct oocyte-sperm transfer (DOST)--a simple alternative to in vitro fertilization (IVF)].

We report on the first pregnancies achieved at our clinic following direct oocyte-sperm-transfer (DOST). Immediately after follicular aspiration, oocytes together with spermatozoa prepared by the swim-up-technique are transferred to the uterus in a manner similar to the embryo transfer following IVF. Our study population consists of 9 patients with bilateral tubal occlusion, accompanied by a male factor in three cases. Up to now, we have achieved four pregnancies, including one twin pregnancy, all occurring, when a male factor was absent. The method described appears promising in terms of efficiency, reduction in the costs and technical procedures during treatment of human infertility.

Embryo Transfer↗
PubMed1991

[Cytogenetic analysis of sperm chromosomes in couples with habitual abortion].

Genetic factors, especially numerical chromosome anomalies, play an important role in embryonic loss. Since somatic cell analysis cannot assess the risk of errors arising de novo during germ cell maturation, we investigated, whether the male gametes from couples with habitual abortion (group HA) carry a higher rate of anomalies, than those from donors without reproductive dysfunction (group K). Chromosomes were demonstrated after fusion of sperm with zona-free golden hamster ova. Our results indicate no significant difference between the two groups for the total rates of aneuploidy (HA: 3.6%, K: 2.0%) and structural anomalies (HA: 15.3%, K: 7.0%). However, the levels of chromosome breaks and acentric fragments were significantly higher in the abortion group (5.8% and 8.1%, respectively, vs. 2.4% each in group K). The implications of this fact remain to be investigated.

Abortion, Habitual↗
PubMed1991

The impact of ovarian laser surgery on the gonadotrophin secretion in women with polycystic ovarian disease.

To evaluate the effects of ovarian surgery on the deranged episodic gonadotrophin release of women with the polycystic ovarian disease (PCOD), we studied 11 patients with the clinical and endocrinological features of PCOD before and after laparoscopic laser coagulations of ovarian surfaces and cysts. During both occasions, blood was collected at 15-min intervals for 8 h to determine LH and FSH secretory profiles and additionally for 3 h during GnRH injections (25 micrograms twice within 2 h) to assess pituitary responsiveness. Serum testosterone, androstendione and oestrogen (oestrone, oestradiol) levels were markedly reduced (P less than 0.05 or less) after surgery. Mean LH concentrations declined (P less than 0.001), while FSH levels increased (P less than 0.01) following laser treatments. The LH pulse frequencies (by Cluster analysis) did not change after ovarian surgery, but the LH pulse amplitudes were markedly reduced (P less than 0.01). Lower (P less than 0.05 or less) LH concentrations were attained in response to GnRH challenges, and the stimulated FSH release also tended to decrease after laser treatments. Thus, ovarian surgery in PCOD women resulted in reduced serum sex steroid concentrations and in divergent effects on serum LH and FSH levels. The attenuated pituitary LH responsiveness after ovarian surgery suggests action of sex steroids primarily at the pituitary site, while the increase in FSH concentrations may be attributed to other factors selectively modulating FSH release.

Adult↗
PubMed1991

Gonadotropin secretion during aging in postmenopausal women.

Although chronological aging is known to result in reduced gonadotropin secretion in women, the precise mechanisms to account for this neuroendocrine manifestation are yet obscure. To evaluate the extent to which the pituitary and/or hypothalamus are involved in the process of aging, we aimed at characterizing the unstimulated and GnRH-stimulated gonadotropin secretion in postmenopausal women (PMW) of different ages. Accordingly, 9 younger PMW (mean age: 53.8 years) in their first and 9 older PMW (mean age: 80.3 years) in their 4th decade of life after natural onset of menopause were studied. In both groups, blood was collected at 10-min intervals for 10 h, while GnRH (25 micrograms i.v.) was administered 8 h after initiation of blood samplings. Compared to younger PMW, basal serum concentrations of dehydroepiandrosterone-sulfate were lower (p less than 0.05) in older PMW, while estrogen (estradiol, estrone), androgen (testosterone, androstendione) and sex hormone binding globulin levels were similar. Lower (p less than 0.01) mean LH levels composed of attenuated (p less than 0.05) LH pulse amplitudes and pulse frequencies (as determined by the cluster pulse algorithm) were found in the 8-hour LH secretory profiles of older PMW. Furthermore, the FSH secretion of older PMW was characterized by lower (p less than 0.01) mean FSH levels with lower (p less than 0.05) FSH pulse amplitudes, but not pulse frequencies. The absolute peak concentrations attained and the total amount of LH and FSH released in response to GnRH stimulations were blunted (p less than 0.001) in older PMW.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Autonomous progesterone secretion from the bovine corpus luteum in vitro.

While the regulation of progesterone secretion from the corpus luteum by LH has been convincingly demonstrated, the secretory patterns in the absence of any pituitary LH inputs are yet unclear. Consequently, we investigated the progesterone secretion by an in vitro perifusion system to characterize spontaneous progesterone release from the isolated bovine corpus luteum. Slices (120 mg) of midluteal corpora lutea were placed in perifusion chambers and continuously perifused by Medium-199 for 160-320 min. Progesterone was determined by radioimmunoassay in the effluent fractions collected at 2-min intervals. The spontaneous progesterone release from all bovine corpora lutea was pulsatile. Pulses were observed at mean (+/- SEM) intervals of 17.7 +/- 1.5 min with amplitudes of 6.7 +/- 0.5 ng and release rates of 29.5 +/- 2.4 ng.ml-1.(2 min)-1 (N = 5). Addition of 6.7 nmol/l hCG to the perifusion medium appeared to increase the pulse amplitudes and release rates (195 +/- 25% over unstimulated conditions), but did not change the pulse frequencies (N = 3). Perifusions with calcium-free medium containing 50 mumol/l verapamil and 20 mmol/l EGTA tended to suppress the pulse frequencies and amplitudes of this spontaneous progesterone release, whereas addition of hCG reversed this decrease again (N = 3). When prostaglandin activity was inhibited by 100 mumol/l indomethacin added to the perifusion medium, both pulse frequencies and amplitudes of this progesterone release were enhanced (N = 4). During perifusions with 100 mumol/l of the anti-progesterone ZK 96.734, both the pulse frequencies and amplitudes increased (N = 4). These studies demonstrate an episodic progesterone release from the bovine corpus luteum perifused in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Repositioning of craniofacial tumorous bone after autoclaving.

Thirteen bone tumours that were invading the craniofacial skeleton were operated on by intracranial procedures. The resected tumorous bone was autoclaved and put back. Follow up of no less than one year included 122mTc scanning, computed tomography, radiography, bone biopsy and clinical examination. In every case, when rigidly fixed, most of the autoclaved bone was gradually revitalised by invading new and normal bone. We conclude that autoclaved bone will be replaced by normal bone, and that the present technique is justified for reconstruction of complicated structures or large areas of bone after operations for tumours invading the craniofacial skeleton.

Adolescent↗
PubMed1991

Pituitary gonadotropin responsiveness to repeated gonadotropin releasing hormone (GnRH) stimulations in patients with chronic anovulation.

To evaluate whether repeated gonadotropin releasing hormone (GnRH) stimulations were superior to single GnRH administrations for the accurate assessment of pituitary gonadotropin responsiveness, the GnRH-stimulated luteinizing hormone (LH) and follicle stimulating hormone (FSH) responses of 49 hyperandrogenic patients (HA) were compared with those of 20 hypogonadotropic patients (HH) and of 24 normally cycling women (N). Blood samples were obtained at frequent intervals during GnRH administrations (25 micrograms twice within 2 h). Unstimulated LH concentrations were higher (p less than 0.001) in HA than in N and HH women. However, basal FSH levels differed only in HA from HH women (p less than 0.001). Following either GnRH stimulation, increased (p less than 0.01) LH and FSH releases were noted in all N, HA and HH women. The GnRH-stimulated LH and FSH responses to either GnRH injections were highest (p less than 0.01) in HA and lowest (p less than 0.01 vs. N) in HH women. The net LH and FSH increases over unstimulated concentrations (delta LH or FSH) in response to either GnRH stimulation were highest (p less than 0.01 or less) in HA women. By contrast, no differences were determined in the delta LH and FSH levels between the first and second GnRH stimulations within each group. These observations document different unstimulated and stimulated gonadotropin concentrations in normal cycling and anovulatory women. Gonadotropin responses to single GnRH administrations differ for anovulatory patients. Since the gonadotropin responses to the second GnRH stimulation are comparable to those during the first GnRH injections, repeated GnRH stimulations may not help to distinguish the degree of pituitary responsiveness in ovulatory from anovulatory women.

Adult↗
PubMed1991

The luteinizing hormone pulsatile secretion: diurnal excursions in normally cycling and postmenopausal women.

While numerous investigations have determined characteristics of episodic luteinizing hormone (LH) secretion in women, any diurnal LH rhythmicities during eugonadal and hypogonadal states have not been accurately addressed. Accordingly, blood was sampled at 15-min intervals for 24 h in 45 normally cycling women (16 early follicular (EFP), 14 late follicular (LFP), 15 mid-luteal phase (MLP) women) and in eight postmenopausal women (PMW). Pulse attributes (amplitudes, interpulse intervals) determined in the LH secretory profiles were fitted to cosinor functions to assess diurnal variabilities. In both eugonadal women and PMW, significant (p less than 0.05 or less) diurnal excursions were observed in mean LH levels, with maximal acrophase amplitudes occurring in the EFP and MLP. While these 24-h swings peaked at comparable times (11.00-17.00) during the menstrual cycles, a significant (p less than 0.001) shift in acrophase times to early morning hours (05.30) was noted for PMW. Significant (p less than 0.05 or less) 24-h periodicities were also found for the LH pulse amplitudes. LH pulses were of greater magnitudes during night hours in both cycling women and PMW. A slowing of LH pulses (p less than 0.05 or less) was noted during sleep in EFP and, distinctly, in MLP women. These observations demonstrate diurnal variations in LH secretion and its pulsatile attributes in eugonadal women. Differences in time course and magnitude of these diurnal excursions may be explained by variations in the sex steroid environments. In turn, steroids may modulate other neuroendocrine determinants regulating central time-keepers.

Aged↗
PubMed1991

[New perspectives of in vitro kallikrein treatment of human spermatozoa. I. Study of the hamster ovum penetration test in relation to different andrologic patient groups].

Whereas the enhancement of motility by Kallikrein is described several times, the effect on fertilizing capacity of human spermatozoa has not been investigated sufficiently yet. This fact induced the authors to start a further investigation on 64 patients by the means of zona-free hamster oocytes. The patients were differentiated by the parameters density and motility. The sample was divided up into two aliquots. Differing from the control the other aliquot was prepared with Kallikrein (5 KU/ml) before swim-up and preincubation for one hour at 22 degrees C. Comparing the results we found looking at the whole collective (n = 64) a significant enhancement of the fertilizing capacity. 34 of 64 patients showed an improvement, only 4 patients deteriorated. While the groups normo-, oligo-, and asthenozoospermia reached a higher fertilizing capacity under Kallikrein-treatment (probability of error 2.5%), a Kallikrein application in case of oligo-asthenozoospermia had no significant influence on fertilizing capacity. A view of the whole results leads to the assumption of a direct effect of Kallikrein and to the possibility of use for GIFT and IVF procedure.

Adult↗