Search PubMed⌕ Search

Biomedical subjects

L Rombauts

Publications and source records attributed to L Rombauts.

33 records · Page 2Linked to original sources
PubMed1995

Gonadotrophin-regulated production of immunoactive inhibin and androgen by cultured testicular cells from chicken embryos.

To study the potential intragonadal role of inhibin and inhibin-related proteins in the developing gonad, a method was developed to culture testicular cells of chicken embryos. A single-step collagenase/DNase digestion was used to disperse the cells. Except for the primordial germ cells and the erythrocytes, the cells attached well to plastic culture dishes. Moreover, they could easily be grown in the absence of serum or other additives. Inhibin secretion was measured using a heterologous radioimmunoassay validated for use in this species. The fetal testicular cells secreted high amounts of immunoactive inhibin and remained responsive to gonadotrophins. Two different cell populations could be recognized in monolayers of testicular cells: the first population had a fibroblast-like stromal appearance, resembling interstitial cells; the second had an epitheloid appearance and contained large numbers of refractile vacuoles, resembling Sertoli cells. Both cell populations were enriched using a Percoll density gradient. The epitheloid cells displayed a higher capacity to secrete immunoactive inhibin, while the stromal cells were responsible for the bulk of androgen secretion. FSH, but also LH, stimulated inhibin secretion in the epitheloid cells. Although ovine LH was the most potent stimulus for androgen secretion by the stromal cells, ovine FSH was also capable of increasing androgen output in stromal cells and to a lesser extent in epitheloid cells. As the two enriched cell populations were still contaminated by other cell types, this may indicate, as in other species, that FSH-induced paracrine factors are involved in the regulation of androgen secretion in the developing gonad.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1995

Developmental changes in immunoreactive inhibin and FSH in plasma of chickens from hatch to sexual maturity.

1. The relationship between immunoreactive inhibin and follicle-stimulating hormone (FSH) was studied in male and female chickens from hatch to sexual maturity. Plasma inhibin was estimated by a heterologous radioimmunoassay validated for use in the chicken. FSH was measured by a recently developed homologous radioimmunoassay. 2. In a cross-sectional study, blood samples and gonads were collected from chickens of both sexes at 1, 3, 5, 7, 14, 21 and 28 d after hatching and subsequently at 14-day intervals until 182 d of age. 3. In the female, plasma progesterone concentration (P4) progressively increased during sexual development. The plasma luteinising hormone (LH) concentration rose during the first week after hatching, and fluctuated thereafter, with troughs at 6 and 14 weeks and peaks at weeks 10 and 18. The plasma inhibin and FSH concentrations remained low until the start of puberty and increased simultaneously thereafter. However, from week 18 on, plasma inhibin continued to rise while plasma FSH fell. Hence, FSH and inhibin were positively correlated before puberty, but developed a negative correlation during sexual maturation. 4. In the male, plasma testosterone and LH concentrations increased 38- and 3.7-fold respectively over the period studied. Inhibin and FSH followed similar time courses and were consequently positively correlated. 5. These results suggest sex differences in the role of inhibin in regulating FSH secretion during development. The FSH-inhibin feedback loop may become operational at the onset of sexual maturity in the hens. In male chickens, the similar pattern of inhibin and FSH secretion suggests that inhibin secretion is driven by FSH.

Aging↗
PubMed1995

Inhibin and steroid responses to testicular stimulation in normal men.

Static measurements of immunoreactive inhibin have proved to be of little relevance in the diagnosis of testicular disorders. To explore whether a dynamic evaluation of inhibin secretion might yield a more useful parameter of testicular function we compared the responses of inhibin with steroids to i.v. injections of pure follicle-stimulating hormone (FSH; 300 IU) or human chorionic gonadotrophin (HCG; 1500 IU) and oral administration of the anti-oestrogen Tamoxifen (20 mg/day for 7 days) in four normal fertile men. Blood was aspirated between 1 and 72 h after the injections and daily during Tamoxifen intake. Four controls were injected with physiological saline solution. An additional four men were injected with pure FSH, and blood was taken after 24, 48 and 72 h. Injection of FSH was accompanied by nycthemeral variations of testosterone comparable with those observed in the controls. The concentration of inhibin showed similar nycthemeral variations but a significant increase was observed in all eight cases at 12 noon on days 2 and 3 after FSH injection. HCG injection resulted in the expected biphasic response of testosterone. Inhibin displayed a pronounced increase 18 h after injection but the delayed response after 48 and 72 h was not observed. Tamoxifen intake increased testosterone but not inhibin, and caused a moderate and temporary increase of luteinizing hormone and FSH. It was concluded that primary stimulation both of Leydig cells by HCG and Sertoli cells by FSH increase circulating inhibin.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Effect of androgens on the germ cell-depleted testes of prenatally irradiated rats.

To study the effect of androgens on somatic testicular cells, rats were rendered germ cell depleted by prenatal irradiation (RX). Adult RX rats were treated with a desensitizing dose of a GnRH agonist (GnRHa; Zoladex), combined with an antiandrogen (Nilutamide) to preclude all androgen effects, or combined with testosterone or hCG to restore androgen action. The effect of these treatments for 3 weeks on the weight of testes and accessory sex glands, hormones (LH, FSH, testosterone, inhibin), testicular proteins, the pattern of incorporation of [35S]-methionine into testicular proteins (studied by two dimensional gel electrophoresis) and steady state mRNA levels for transferrin and androgen-binding protein (ABP) were evaluated. Combined treatment with GnRHa and antiandrogen virtually eliminated gonadotrophins, androgens and androgen effects. Testicular weight was reduced to 50% of that observed in RX controls. Treatment with GnRHa and testosterone resulted in supraphysiological levels of testosterone and testicular weights comparable to those observed in RX controls. FSH levels in these animals, however, were in the normal range. A low dose of hCG also restored testicular weight in the presence of low concentrations of serum testosterone and low normal levels of FSH. Neither polyacrylamide gel electrophoresis of total testicular proteins nor two dimensional gel electrophoresis of [35S]-methionine labelled proteins revealed striking changes in distinct testicular proteins as a result of androgen withdrawal or androgen treatment. Dot blot hybridization showed a three-fold increase in the mRNA level for ABP (expressed per microgram total RNA) in the Sertoli cell enriched testes of RX rats. This level was barely influenced by androgen withdrawal or androgen administration. The mRNA level for transferrin was increased six-fold in RX rats. A 50% reduction of this level was observed after combined treatment with GnRHa and antiandrogen. It is concluded that, in the germ cell-depleted testis, the major effect of androgens is an overall increase in protein and RNA synthesis rather than a very important and selective increase of a few gene products.

Androgen Antagonists↗
PubMed1994

Changes of immunoreactive inhibin, follicle-stimulating hormone, luteinizing hormone, and progesterone in plasma after short-term food deprivation and during the ovulatory cycle of the domestic hen.

The interrelationship between immunoreactive inhibin and follicle-stimulating hormone (FSH) was measured in laying hens after short-term food deprivation and during the ovulatory cycle. Plasma inhibin was estimated by a heterologous radioimmunoassay validated for use in chicken. FSH was measured by a recently developed homologous radioimmunoassay. Ten hens were deprived of food for 10 days (a method to induce artificial moult or to stop egg laying). Blood samples were taken daily via the brachial vein for 10 consecutive days starting on the day of food withdrawal. The data are expressed in relation to the last day of oviposition. Short-term food deprivation, followed by ovarian atrophy, significantly depressed the plasma inhibin and progesterone (P4) concentration. Plasma FSH concentrations significantly increased, while luteinizing hormone (LH) concentrations slightly but not significantly decreased. In another experiment, 6 hens were induced to moult. The control hens (n = 6) were fed ad libitum. On Day 17, the hens were killed and follicular distribution was studied. The atrophy of the large yolky follicles in restricted hens was associated with a significant increase in the number of white follicles. In a third experiment, serial blood samples were taken from hens (n = 15) at 2-hr intervals for 36 hr via a brachial cannula. Plasma immunoreactive inhibin and FSH concentrations did not vary during the ovulatory cycle. LH and P4 increased simultaneously from basal levels to preovulatory peak values 6 hr before ovulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Different cells and cell lines produce factors that modulate Sertoli cell function.

Peritubular myoid cells derived from immature rat testes produce factors that modulate Sertoli cell function (P-Mod-S). The secretion of these factors is controlled in part by androgens. Cultured prostatic stromal cells strongly resemble peritubular myoid cells and produce mediators with similar activity. Here we investigated whether myoid cell lines can be used as a source of P-Mod-S-like factors. Rat kidney fibroblast (NRK) and mouse fibroblast (3T3) cell lines were used as non-myoid controls. Surprisingly, serum-free media conditioned by all cell lines studied modulated Sertoli cell function in a similar fashion as media conditioned by peritubular cells (PTCM) or stromal cells (STCM). Using Sertoli cell transferrin secretion as an endpoint for P-Mod-S-like activity, the nature of the active principles involved was further explored. The observed activity could not be explained by residual contamination with fetal calf serum. Moreover, the effects of the conditioned media could not be mimicked by classical growth factors (IGF-I, bFGF, EGF, TGF-beta, NGF, PDGF-BB) added singly or in combination with submaximally effective concentrations of PTCM. Finally, the possibility that conditioned media might indirectly enhance Sertoli cell function by promoting the production or deposition of extracellular matrix elements was made unlikely by the demonstration that the observed effects were not mimicked by Matrigel and were unaffected when Sertoli cells were seeded on Matrigel. Superdex 75 chromatography after analytical reversed-phase chromatography indicates that the factors from different origin have a similar size (45-50 kDa). It is concluded that mediators with P-Mod-S-like activity are produced by various cells and cell lines both with and without smooth muscle cell characteristics. Whether the active principles involved are really identical requires further investigation.

Animals↗
PubMed1994

Secretion of steroids, growth factors, and cytokines by immortalized mouse granulosa cell lines.

The expression and function of gonadotropin receptors, and the secretion of steroids, transferrin, and cytokines were investigated in three immortalized (single transfection with v-myc) mouse granulosa cell lines (GRM01, GRM01L, and GRM02). A dose-dependent increase in progesterone production was obtained in GRM01 and GRM02 cells after addition of LH, FSH, modulators of the adenylate cyclase enzyme system, and cAMP analogues. The LH-induced release of progesterone was already detectable in GRM02 cells after 8 h and was related to incubation time and cell number. Both epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) induced the secretion of progesterone in GRM02 cells, while no effect was obtained with TGF beta. LH receptor concentration was highest in the GRM02 cell line. FSH receptor mRNA was visualized in GRM01 and GRM02 cells. Aromatase activity in GRM02 cells was induced by androgens and inhibited by aromatase inhibitors. Whereas all cell lines were able to secrete transferrin, only in GRM01 cells was transferrin secretion increased significantly by LH. FSH did not affect transferrin secretion in the three cell lines, in contrast to forskolin or 8-bromo-cAMP. The immortalized mouse granulosa cell lines were able to express and release several growth factors. The expression and secretion of activin, inhibin, TGF beta, EGF, TGF alpha, insulin-like growth factor II, fibroblast growth factor (acidic and basic), platelet-derived growth factor, and interleukin-6 suggest an autocrine or paracrine role for these factors in follicular differentiation and function. In conclusion, these cells, derived from mural granulosa cells and immortalized in a preovulatory state, can be used to study granulosa cell physiology or to study the role of granulosa cells and their derivatives in the process of follicular maturation, fertilization, and early embryonic development.

Adenylyl Cyclases↗
PubMed1994

Contribution of the fetal adrenal to circulating immunoactive inhibin in the chicken embryo.

High concentrations of immunoactive inhibin are observed in the plasma of male and female chicken embryos. The exact nature and the source of this material remain obscure. In a previous study we presented evidence that the fetal gonads are unlikely to be the main source of circulating inhibin (Biol Reprod 1993; 49:549-554). Here we demonstrate that the fetal adrenal may account for the major portion of circulating immunoactive inhibin in the chicken embryo. A comparison of the inhibin content of different fetal organs shows that, expressed per milligram of tissue, the adrenal ranks second. Only the testis has a higher inhibin content, while the inhibin content of the fetal ovary is considerably lower than that of the fetal adrenal. Suppression of endogenous ACTH secretion by administration of dexamethasone results in a marked decrease of plasma inhibin. Maximal suppression (down to 24% and 25% of the control values in male and female embryos, respectively) was observed with the lowest dose of dexamethasone tested (1 microgram/egg). Dexamethasone (100 microgram/egg) reduced testicular weight and testicular inhibin content to approximately 50% of the control value. It is unlikely, however, that this contributed significantly to the fall in circulating immunoactive inhibin. In fact, ovarian inhibin content was unaffected, but even so, a comparable drop in circulating inhibin was observed in female embryos. Dexamethasone caused only marginal changes in plasma FSH. Administration of a synthetic peptide with ACTH activity (Synacthen) in vivo did not produce measurable changes in circulating inhibin. Isolated and cultured fetal adrenal cells, however, produced immunoactive inhibin, and this production was increased fivefold after stimulation with synthetic ACTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1993

Changes in immunoreactive FSH and inhibin in developing chicken embryos and the effects of estradiol and the aromatase inhibitor R76713.

The interrelationship between immunoreactive inhibin and FSH was measured in chicken embryos from Day 8 to Day 20 of the incubation period. Plasma inhibin was measured by a heterologous RIA and FSH by a recently developed homologous RIA. Male and female inhibin plasma concentrations demonstrated a similar time course: a sharp increase with a peak on Day 13 was followed by a drop towards Day 18, after which inhibin levels stabilized. In male embryos, a similar time course was observed for the FSH concentrations. In sharp contrast, the FSH concentrations in the female embryos remained low and unchanged throughout the incubation period. Accordingly, sex differences were large for FSH and rather small for inhibin, and were noted from Day 10 and Day 12 on, respectively. No obvious inverse relationship was observed between inhibin and FSH. In male embryos, estradiol administration resulted in a dose-related decrease in FSH, accompanied by a less pronounced decrease in inhibin. Treatment with an aromatase inhibitor (R76713) increased FSH in female embryos and inhibin in both sexes. Generally, the experimentally induced changes in FSH were accompanied by comparatively small changes in inhibin. In conclusion, these observations suggest 1) that estradiol is an important inhibitor of pituitary FSH secretion in the chicken embryo, 2) that inhibin is not likely to play a major role in the feedback regulation of the hypothalamo-pituitary-gonadal axis, and 3) that an important fraction of the measured inhibin immunoactivity escapes the control of FSH. In view of the present data, the hypothesis is advanced that the gonads are not the major source of circulating immunoreactive inhibin in the chicken embryo.

Animals↗
PubMed1993

Effect of oestrogen status on serum levels of growth hormone-binding protein and insulin-like growth factor-I in non-pregnant and pregnant women.

OBJECTIVE: Since there appears to be a relationship between circulating oestrogens and growth hormone, we have investigated the effect of the oestrogen status of adult women on serum levels of GHBP and IGF-I. DESIGN AND PATIENTS: The investigation was performed on serum samples of 14 spontaneously menstruating women, 10 women taking oral contraceptives containing 20-50 micrograms ethinyloestradiol, and 30 pregnant women at different stages of pregnancy. MEASUREMENTS: Serum levels of GHBP were measured by HPLC gel filtration and IGF-I levels were measured by RIA after acid-ethanol extraction. RESULTS: In the spontaneously menstruating women the mean +/- SD serum level of GHBP was 34.6 +/- 6.7% and of IGF-I 30 +/- 7 nmol/l. Serum GHBP levels were negatively (r = -0.67; P < 0.01) and IGF-I levels were positively related (r = 0.69; P < 0.01) to serum oestradiol concentrations. In the women taking oral contraceptives serum levels of GHBP were 47.0 +/- 7.4%. This was significantly (P < 0.001) higher than in spontaneously menstruating women. In contrast, IGF-I levels were not different from those obtained in spontaneously menstruating women. In the pregnant women, the mean +/- SD serum level of GHBP was not different from that observed in non-pregnant spontaneously menstruating women. Polynomial regression analysis, however, showed a significant (P = 0.01) second-order relationship between the duration of pregnancy and serum GHBP levels, with increasing levels during the first half of pregnancy and decreasing levels thereafter. Serum concentrations of IGF-I increased during the second half of pregnancy and were significantly (P < 0.005) elevated in the third trimester. CONCLUSIONS: In non-pregnant women the endogenous oestrogen status seems to modulate negatively GHBP levels and positively IGF-I levels, whereas oral oestrogen administration, in contrast, increases serum levels of GHBP without modification of IGF-I levels. During pregnancy serum GHBP levels increase slightly during the first half of pregnancy and decrease thereafter, whereas IGF-I concentrations increase during the second part of pregnancy. The oestrogen status of women has a complex effect on serum concentrations of GHBP and IGF-I and has therefore to be taken into account when evaluating serum levels of GHBP and IGF-I.

Administration, Oral↗
PubMed1992

The role of cell-cell interactions in androgen action.

Androgen-regulated mesenchymal-epithelial interactions play an important role during embryonic development of the male urogenital tractus. Studies on the effects of androgens on cultured testicular cells derived from the immature rat testis indicate that, even during postnatal life, similar interactions may be instrumental for normal androgen action. Androgen receptors are found in epithelial Sertoli cells as well as in mesenchymal peritubular cells. The effects of androgens on isolated Sertoli cells, however, are limited. Coculture with peritubular cells increases the sensitivity and/or the responsiveness of a number of Sertoli cell parameters (transferrin, ABP, aromatase activity) to androgens. This effect is at least in part mediated by the secretion of one or more diffusible factors (P-Mod-S) by the peritubular cells. We investigated whether such indirect effects of androgens, relying on mesenchymal-epithelial interactions are also observed in other androgen target tissues. To this end stromal cells were isolated and cultured from the immature rat ventral prostate and the production of factors with P-Mod-S activity was monitored using Sertoli cells as the test system. Under coculture conditions these stromal cells stimulate Sertoli cell transferrin secretion in an androgen-regulated fashion, exactly as peritubular cells. This stimulatory effect is related in part to the collaborative (and androgen-independent) deposition of an extracellular matrix and in part to the secretion of an androgen-regulated diffusible mediator. This mediator has the same physicochemical characteristics as P-Mod-S and it affects other Sertoli cell parameters (ABP, aromatase activity, inhibin, cGMP) in the same way as P-Mod-S. Cultured stromal and peritubular cells look very similar and stain positive after immunostaining for alpha-smooth muscle isoactin. Tissue sections suggest that these cells may be derived from myoid peritubular cells in the testis and similar periacinar cells in the prostate. The hypothesis is advanced that P-Mod-S may be a more universal mediator of indirect effects of androgens in diverse target tissues and that this factor is derived from myoid cells closely associated with the epithelial component.

Animals↗
PubMed1992

Immunoreactive inhibin in plasma, amniotic fluid, and gonadal tissue of male and female chick embryos.

Immunoreactive inhibin was measured in plasma, amniotic fluid, gonads, and Wolffian bodies (mesonephros) of male and female chick embryos during the last week of their 21-day incubation period. The antiserum used was raised against bovine 31-kDa inhibin and was validated for RIA of inhibin in the chicken. Amniotic fluid concentrations of immunoreactive inhibin were relatively low and remained constant between Days 14 and 19. Plasma concentrations, in contrast, were high on Day 14 but declined steeply thereafter. Significantly higher plasma concentrations were noted in male than in female embryos and an even more pronounced sex difference was observed for the gonadal inhibin content. On Day 21, testes contained approximately 35 times more immunoreactive inhibin than ovaries. Surprisingly, inhibin contents in testes and male Wolffian bodies increased rather than decreased towards the end of the incubation period, indicating that gonadal and plasma inhibin concentrations are regulated, at least in part, independently. It is concluded that the chick embryo presents a convenient model for study of the secretion, the control, and the role of inhibin from fetal origin. The sex difference in plasma and gonadal inhibin suggests a differential role of inhibin in the development of the reproductive system of both sexes.

Amniotic Fluid↗
PubMed1992

Source of immunoreactive inhibin in the chicken ovary.

High concentrations of immunoreactive inhibin were detected in the plasma of the laying domestic hen using a heterologous RIA validated for use in the chicken. Cessation of egg production induced by restricting the intake of nutrients decreased circulating inhibin to approximately 20% of its original concentration within 8 days, indicating that the ovary is the major source of the measured material. Dissection of ovarian follicles revealed that inhibin is nearly exclusively produced in the granulosa cell layer. When expressed per milligram cell protein the concentration of inhibin decreased significantly in granulosa layers of follicles of succeeding order in the hierarchy (F4 to F1). The concentration of progesterone increased in the granulosa layers of the same follicles whereas oestradiol in the surrounding theca layers decreased. In vitro culture of granulosa cells derived from follicles at different stages of development confirmed the decrease in inhibin secretion as a function of follicular growth observed in vivo. The granulosa cell inhibin secretion is stimulated by LH as well as by FSH, the former being the most effective one. The physiological significance of these changes in inhibin concentration during follicular maturation requires further investigation. It may be concluded, however, that the chicken presents a useful model for the study of the endocrine as well as the paracrine function of ovarian inhibin.

Analysis of Variance↗
PubMedDate not supplied

Office mini-hysteroscopy.

The technique of diagnostic hysteroscopy has not yet been accepted generally as an ambulatory, well-tolerated office procedure. Especially in the infertile patient the standard hysteroscopic procedure is poorly tolerated in an office environment. Our prospective registration of 530 diagnostic office mini-hysteroscopies in infertile patients demonstrates that using an atraumatic insertion technique, watery distention medium and the new generation of mini-hysteroscopic endoscopes, hysteroscopy can be performed in an office set-up without any form of anaesthesia and with a high patient compliance. The significant number of abnormal findings (28.5%), the absence of complications and the low failure rate (2.3%) indicate that diagnostic office mini-hysteroscopy should be a first-line diagnostic procedure. Those results are compared with the registration of 4204 consecutive conventional diagnostic hysteroscopies in a routine gynaecological population performed between 1982 and 1989. We conclude that the mini-hysteroscopic system offers a simple, safe and efficient diagnostic method in the office for the investigation of abnormal uterine bleeding, to evaluate the cervix and uterine cavity in the infertile patient, for screening of endometrial changes in patients under hormone replacement therapy or anti-oestrogens as (adjuvant) treatment and, lastly, it may be very helpful for the interpretation of uncertain findings in other diagnostic techniques such as ultrasound, magnetic resonance imaging, blind biopsy or hysterosalpingography.

Ambulatory Surgical Procedures↗