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Biomedical subjects

R Scholler

Publications and source records attributed to R Scholler.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Pulsatile administration of GnRH: from the future to the present].

Since the first clinical reports of the successful induction of ovulations and pregnancies using pulsatile administration of the neuropeptide GnRH by G. Leyendecker and L. Wildt's group in 1979, the role of the hypothalamic generator, as demonstrated in primates by E. Knobil, is widely accepted in human reproduction. During this time, an increasing number of group has experienced these therapies and there continues to be some controversies about the route of administration, the indications, the need for adjuvant therapies. A correct evaluation of these therapies needs multicentric studies and more accurate criteria: the MINITEL network provides a fast, inexpensive way to collect data from different groups and to perform studies with larger sample sizes. The Life table analysis method represents the more suitable method for evaluating and for comparing various therapy regimens. LH plasma pulsatility studies have been performed in humans in order to classify various "supra-pituitary" reproductive disorders. These studies are exposed to several methodological drawbacks and must be cautiously interpreted. Modelling is one of the new methodological issues which can give access to more physiological parameters.

Female↗
PubMed1987

Inhibition of the preovulatory LH surge after a catecholestrogen (2-hydroxyestrone) antiserum injection in the third ventricle of cycling female rats.

Administration of a catecholestrogen (2-hydroxyestrone, 2-OHE1) antiserum (2-OHE1-AS) in the third ventricle of cycling female rats, on the morning of proestrus, leads to a significant reduction in the afternoon LH surge. These responses are dose-dependent and can be observed even when the 2-OHE1-AS is injected on the diestrus morning. Almost similar results were obtained with an antiserum against 17 beta-estradiol (17 beta-E2). Nevertheless, the fact that the central immunoneutralization of 2-OHE1 impedes the preovulatory surge of LH at a time of high peripheral levels of 17 beta-E2 strengthens the idea of a specific role for 2-OHE1 in the control of cycling LH release.

Animals↗
PubMed1987

Radioimmunoassay of plasma progesterone after oral administration of micronized progesterone.

A 200 mg dose of micronized progesterone (P) was administered orally to six healthy volunteers. Serial blood samples were collected and plasma P was assayed according to three methods of different specificity. The results were compared to those obtained with a reference technique based on gas chromatography-mass spectrometry. The interference of P metabolites particularly 5 alpha- and 5 beta-dihydroprogesterone was shown to be important when no or inadequate chromatography was included in the method. Radioimmunoassay after chromatography on a Celite column yielded results similar to those of the reference method. After oral administration, plasma P reached a peak at 3.00 +/- 0.44 h (mean +/- SEM; range: 1-4 h). The mean peak level 4.70 +/- 1.15 ng/ml (mean +/- SEM; range: 2.40-10.10 ng/ml) was at the lower limit of the range defined for a normal functional corpus luteum. The levels returned to initial values by 24 h after the single oral dose. The separation of P from its metabolites by an adequate chromatographic system appears mandatory after oral administration of micronized P.

Administration, Oral↗
PubMed1987

Comparison of saliva and plasma 17-hydroxyprogesterone time-course response to hCG administration in normal men.

17-Hydroxyprogesterone (17-OHP) time-course response to hCG (5000 IU) was studied simultaneously in the saliva and the plasma of 12 adult healthy men. Baseline levels in plasma and saliva were: 1.0 +/- 0.1 ng/ml (mean +/- SEM) and 24 +/- 2 pg/ml respectively. After hCG, a biphasic pattern was observed in both fluids with a similar early response but the peak elicited at 33 h in plasma was not observed in saliva where the levels were lower than those recorded at 24 h. Since saliva steroids are believed to reflect the plasma non-protein bound fraction, this difference was assumed to be due to the decrease of the unbound fraction of plasma 17-OHP in the late afternoon as a consequence of the increase of CBG-bound fraction since at that time cortisol levels are low. The ratio of saliva to plasma 17-OHP levels was significantly correlated with plasma cortisol levels: r = 0.44 (P less than 0.01; n = 140). However the similar response in saliva at 24 and at 48 h after hCG allows the evaluation of the endocrine testicular function using saliva instead of plasma.

17-alpha-Hydroxyprogesterone↗
PubMed1987

Steroid 21-hydroxylation by human preovulatory follicles from stimulated cycles: a mass spectrometrical study of deoxycorticosterone, 21-hydroxypregnenolone and 11-deoxycortisol in follicular fluid.

A highly specific technique based on gas chromatography-mass spectrometry associated with stable isotope dilution was applied to the analysis of follicular fluid aspirated from preovulatory follicles of women under ovarian stimulation prior to in vitro fertilization. Deoxycorticosterone, 21-hydroxypregnenolone and 11-deoxycortisol have been identified and quantified in the nanomolar concentration range. Significant positive correlations were found between these 21-hydroxy-steroids and their immediate precursors, thus indicating a probable common cellular origin. Corticosterone was tentatively identified and cortisol was evidenced at concentrations lower than peripheral plasma levels. The occurrence in human follicular fluid of cortisol, together with different high concentration intermediates, constitutes evidence for ovarian intra-follicular 21-hydroxylase activity, and probably also for 11 beta-hydroxylation enzyme activity.

17-Hydroxycorticosteroids↗
PubMed1987

Androgen and 19-norsteroid profiles in human preovulatory follicles from stimulated cycles: an isotope dilution-mass spectrometric study.

Follicular fluid was aspirated from preovulatory follicles of women under ovarian stimulation for in vitro fertilization and analyzed by a highly specific technique based on gas chromatography-mass spectrometry associated with stable isotope dilution. 19-Nortestosterone and 19-norandrostenedione were identified and quantified for the first time in human follicular fluid. There was a strong positive correlation between 19-nortestosterone and estradiol-17 beta and between 19-norandrostenedione and estrone concentrations, thus indicating a common cellular origin. The accumulation of 19-norsteroids in follicular fluid confirms that they are weakly active intermediates in the multistep enzymatic conversion of androgen to estrogen. Testosterone concentrations were significantly lower than those obtained by radioimmunoassay; cross-reaction with substantially higher levels of 19-nortestosterone seems to be at the origin of this discrepancy. Androstenedione concentrations were similar to those reported in the literature and it was therefore confirmed that an estradiol/androstenedione concentration ratio above 20 is favourable for oocyte cleavage. Other and some newly estimated androgens are: testosterone sulfate, 5-androstene-3 beta, 17 beta-diol 3-sulfate and disulfate, dihydrotestosterone sulfate, epitestosterone, 19-hydroxyandrostenedione, 5 alpha-androstane-3 alpha, 17 beta-diol, 5 alpha-androstane-3 beta, 17 beta-diol, 5 alpha-androstane-3,17-dione and androsterone. Dehydroepiandrosterone sulfate was by far the most abundant androgen in this type of follicles.

Androgens↗
PubMed1987

Stimulation of estradiol-17 beta secretion by 7,12-dimethylbenz (a) anthracene during mammary tumor induction in Sprague-Dawley rats.

Testosterone, androstenedione, progesterone, 17-hydroxyprogesterone, estrone and estradiol-17 beta serum levels were measured at given times after dimethylbenz (a) anthracene (DMBA) treatment of a sensitive rat strain Sprague-Dawley (S-D) and a resistant strain Wistar (W). Tumors appeared with a 100% incidence around the 14th to 15th estrous cycle after DMBA treatment in in Sprague-Dawley rats. Hormonal determinations were made, during the 5th or 6th estrous cycle after DMBA treatment, in groups of 4-day cycling rats of both strains which were given DMBA or the carrier solution (sesame oil) when they were about 55-days old. In Sprague-Dawley female rats, DMBA treatment significantly stimulated estradiol-17 beta and estrone preovulatory surge on proestrous days. No such stimulation was found for any other steroid at any time of the estrous cycle. On the other hand, the resistant Wistar rats did not show any disturbed preovulatory or basal steroid hormone release after the carcinogen treatment. These results complete and explain previous findings concerning the hypothalamo-pituitary activity after DMBA treatment of S-D rats: an early and persistent alteration in the centers involved in the hormonal cyclicity of the hypothalamo-pituitary-ovarian axis must be a result of the DMBA treatment. This deregulation could probably account for the distant and selective production of tumors in the mammary gland induced by a single gastric administration of DMBA.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Gonadotropin and alpha-subunit secretion during long term pituitary suppression by D-Trp6-luteinizing hormone-releasing hormone microcapsules as treatment of precocious puberty.

Short term treatment with GnRH agonists has been reported to increase plasma gonadotropin alpha-subunit (Gn alpha) levels while decreasing plasma immunoreactive LH (IR-LH) levels. In this study we examined the effect of D-Trp6-LHRH (LHRH-A) in microcapsules (60 micrograms/kg, im, every 28 days for 1 yr) in 13 girls suffering from precocious puberty. Plasma IR-Gn alpha was measured by RIA; plasma IR-LH and IR-FSH were measured by both polyclonal RIAs and monoclonal immunoradiometric assays (IRMA). Before treatment, basal IR-LH and IR-FSH levels and peak responses to LHRH measured by both RIA and IRMA were similar, and the Gn alpha response paralleled that of LH. After the first injection of LHRH-A, RIA LH levels were significantly higher than pretreatment levels until day 21, while IRMA LH levels transiently increased, but returned to pretreatment levels by day 7 and became lower thereafter (P less than 0.005). Plasma IR-Gn alpha levels increased from days 3-21 (P less than 0.05). After 1.5 months of treatment, basal RIA LH levels remained detectable and not different from pretreatment levels; IRMA LH levels were very low. The mean RIA and IRMA LH responses to LHRH were decreased at 1.5 and 12 months (P less than 0.01). Basal plasma RIA and IRMA FSH levels were similar during treatment (P greater than 0.05) and significantly lower than pretreatment values (P less than 0.01). The mean RIA and IRMA FSH responses to LHRH decreased significantly at 1.5 months (P less than 0.001). After 12 months, both RIA and IRMA FSH responses were increased, but IRMA values were significantly lower than RIA values. A sustained increase in basal Gn alpha values occurred, but there was a tendency for the peak levels after LHRH treatment to decrease, becoming significantly lower than pretreatment peak levels after 1 yr. The chromatographic analysis on Sephadex G-100 of a pool of plasma samples collected during a LHRH test in three children treated for 6 months indicated that IR-Gn alpha coeluted with [125I]Gn alpha. The large discrepancy between RIA and IRMA LH values suggests the secretion of unusual LH molecules which are recognized by RIA but not by IRMA. The sustained release of large amounts of IR-Gn alpha indicates dissociated effects of LHRH-A on alpha- and beta-subunit secretion by the gonadotrophs. The sustained response of Gn alpha to LHRH demonstrates that gonadotroph cell LHRH receptors are still responsive to LHRH during treatment with a LHRH agonist.

Capsules↗
PubMed1987

Effects of melatonin implantation on spermatogenesis, the moulting cycle and plasma concentrations of melatonin, LH, prolactin and testosterone in the male blue fox (Alopex lagopus).

Melatonin administration to male blue foxes from August for 1 year resulted in profound changes in the testicular and furring cycles. The control animals underwent 5-fold seasonal changes in testicular volume, with maximal values in March and lowest volumes in August. In contrast, melatonin treatment allowed normal redevelopment of the testes and growth of the winter coat during the autumn but prevented testicular regression and the moult to a summer coat the following spring. At castration in August, 88% of the tubular sections in the testes of the controls contained spermatogonia as the only germinal cell type, whereas in the treated animals 56-79% of sections contained spermatids or even spermatozoa. Semen collection from a treated male in early August produced spermatozoa with normal density and motility. Measurement of plasma prolactin concentrations revealed that the spring rise in plasma prolactin values (from basal levels of 1.6-5.4 ng/ml to peak values of 4.1-18.3 ng/ml) was prevented; values in the treated animals ranged during the year from 1.8 to 6.3 ng/ml. Individual variations in plasma LH concentrations masked any seasonal variations in LH release in response to LHRH stimulation, but the testosterone response to LH release after LHRH stimulation was significantly higher after the mating season in the treated animals, indicating that testicular testosterone production was maintained longer than in the controls. The treated animals retained a winter coat, of varied quality and maturity, until the end of the study in August.

Animals↗
PubMed1987

Lateral diffusion of a human sperm-head antigen during incubation in a capacitation medium and induction of the acrosome reaction in vitro.

An integral component of human spermatozoa, a glycoprotein of Mr 143,000 (two subunits of Mr 76,000 and 67,000) was recognized by the a-HS 1A.1 monoclonal antibody. The antigen was localized on the plasma membrane over the sperm head, as demonstrated by transmission electron microscopy. The antigen-antibody binding on gametes during changes in their functional state was followed by an indirect immunofluorescence assay of live human spermatozoa. In freshly ejaculated spermatozoa the antibody binding pattern revealed a patchwork quilt-like topography of the plasma membrane over the acrosome; the percentage of positive cells varied from 20 to 78% with a mean of 50% (n = 82). Incubation in a capacitation medium could increase this percentage up to 98%, revealing new epitopes in an energy-dependent and temperature-independent manner; concomitantly, a part of the antigen migrated in energy-independent and temperature-dependent manner and accumulated in a ring over the postacrosome. When an acrosome reaction was induced in vitro in the presence of Ca2+ with either A23187, ionomycin or human follicular fluid, the HS 1A.1 antigen migrated until immobilization in a well defined pattern around the equatorial segment (single band) or around the equatorial and postacrosomal segments (2 or, seldom, 3 bands). The new antigen localization resulted from a lateral diffusion of pre-existing molecules, occurred in only a few minutes, did not require energy and was temperature-dependent. At the same time, the well outlined large patch burst into a multitude of small spots before vanishing. this veil-like labelling was often observed in spermatozoa kept in the seminal plasma or treated with a metabolic poison. The HS 1A.1 antigen localization reflects surface changes induced by the incubation in a capacitation medium and the acrosome reaction. Apart from the regional heterogeneity of the plasma membrane of a single cell, as noted above, there were differences in the plasma membrane changes in individual spermatozoa from the same ejaculate as well as in semen samples from different donors. The new antibody binding pattern was often alike in successive ejaculates of the same donor. In patients consulting for infertility the percentage of positive cells was often low and migration of the antigen was slight or absent.

Acrosome↗
PubMed1987

Sexual development in the immature male blue fox (Alopex lagopus), investigated by testicular histology, DNA flow cytometry and measurement of plasma FSH, LH, testosterone and soluble testicular Mn2+-dependent adenylate cyclase activity.

Testicular weight in young male blue foxes increased steadily from 12 weeks of age (0.4-0.7 g) to reach peak values at the time of the mating season in March-April (5.2-6.6 g), before declining rapidly during May to low values in August at 63 weeks of age (1.3-1.6 g). Primary spermatocytes were found in the spermatogenic epithelium at 20 weeks of age and by late December (29 weeks of age) elongated spermatids were seen. There was a good correlation between the seasonal variations in the presence of germ cell types assessed by quantitative analysis of testicular histology and the variations in numbers of haploid, diploid and tetraploid cells measured by DNA flow cytometry: no haploid cells were found before the end of November and peak numbers were observed in March. Plasma FSH concentrations were increased from December onwards (with the exception of April). There were no clearcut seasonal variations in plasma LH concentrations although values were consistently lower in April. Testosterone concentrations were low for most of the year but increased from the end of January to the middle of April. There was no detectable seasonal variation in LH release in response to LHRH injection, and no typical pattern in plasma FSH concentrations during the first 100 min after injection. Plasma testosterone concentrations after LHRH injection rose gradually during testicular development. There were large seasonal variations in soluble Mn2+-dependent adenylate cyclase activity in the testis, that paralleled the changes in testicular weight and haploid cell content. Values were low until December and reached a peak at the time of the mating season before falling to basal levels again by June. The results suggest that immature male blue foxes reach full testicular development (indistinguishable from that of older animals) by the first mating season after birth at, an age of about 40 weeks.

Adenylyl Cyclases↗
PubMed1987

Preliminary studies of the effects of bromocriptine on testicular regression and the spring moult in a seasonal breeder, the male blue fox (Alopex lagopus).

Bromocriptine administration in the form of slow-release injections to male blue foxes during March-May abolished the normal spring rise in plasma prolactin concentrations seen in May and June. The spring moult was prevented and the treated animals retained a winter coat of varied quality and maturity until the end of the study in August. Plasma testosterone concentrations fell normally from March until August. Testicular regression was, however, delayed, although there were individual variations in response. Estimation by DNA flow cytometry in early July of the relative numbers of haploid, diploid and tetraploid cells in the testis showed that, in the treated animals, 74-80% of the cells were haploid (maturing germinal cells), 4-6% tetraploid (mainly primary spermatocytes) and the rest diploid cells (somatic cells and the remaining germinal cell types). In the control males, however, no haploid cells were detected and the majority of cells were diploid (93-99%). At castration in August, histological examination revealed various stages of testicular regression in the treated and control animals.

Animals↗
PubMed1987

Primate specific sialoglycoprotein of sperm head plasma membrane defined by an anti-carbohydrate monoclonal antibody.

A sialoglycoprotein, an integral component of the head plasma membrane of human spermatozoa, is recognized by the a-HS 1A.1 monoclonal antibody. The antigenicity is associated with the sugar moiety since: a) trypsin digestion did not affect the antigenic determinant; b) pretreatment of the cells with beta-glucosidase, alpha-mannosidase and neuraminidase completely abolished antibody binding. Endoglycosidase D and glycopeptidase F were inactive. The a-HS 1A.1 did not recognize a variety of blood-group related synthetic oligosaccharides. The species specificity was studied by indirect immunofluorescence assay. The antibody also recognized an antigen on Macaca fascicularis sperm, but failed to bind to spermatozoa of boar, bull, goat, ram, stallion, dog, rabbit, rooster, carp and eel.

Animals↗
PubMed1986

Saliva testosterone time-course response to hCG in adult normal men. Comparison with plasma levels.

Testosterone time-course response to 5000 IU hCG was studied simultaneously in the saliva and the plasma of 13 adult normal men. Baseline levels in saliva and plasma were: 93 +/- 9 pg/ml (mean +/- SEM) and 4.9 +/- 0.3 ng/ml respectively. After hCG the same biphasic pattern was observed in both fluids with a similar early response but the delayed peak at 72 h was relatively higher in saliva than in plasma. Thus it was suggested to collect saliva instead of plasma for the evaluation of testicular secretion of testosterone after hCG administration.

Adult↗
PubMed1986

Rat testis 17 beta-estradiol: identification by gas chromatography-mass spectrometry and age related cellular distribution.

The aromatization of testosterone into 17 beta-estradiol (E2) was assessed in purified Leydig and Sertoli cells from rats aged 10-80 days. E2 was identified by gas chromatography-mass spectrometry (GC-MS) and measured both by radioimmunoassay (RIA) and GC-MS associated with stable isotope dilution. A potent competitive inhibitor of the aromatase activity, 4-hydroxyandrostenedione (4-OH-A) was used to test the enzymatic specificity. The basal aromatase activity was present in both cell types whatever the age of the animals. The basal E2 levels did not vary in Sertoli cells while a gradual increase was noted in Leydig cells until day 40, followed by a slight decrease in mature rats. In 10-day old animals, the aromatase activity was localized in Sertoli cells and highly stimulated by FSH; on day 20, both Sertoli and Leydig cells synthesized E2 although E2 from Sertoli cell origin was still predominant. Starting on day 20 until adulthood, the aromatase activity was under LH control in Leydig cells with a maximum around 40 days. The FSH and LH effects were mediated by cyclic AMP.

Aging↗
PubMed1986

Radioimmunoassay of 5-androstene-3 beta,17 beta-diol in plasma and in breast cyst fluid.

A simple and reliable radioimmunoassay for the determination of 5-androstene-3 beta, 17 beta-diol in peripheral plasma and in breast cyst fluid, after a chromatography on Celite microcolumn has been described and evaluated. The antiserum used was raised in rabbits injected with dehydroepiandrosterone-15 alpha-(O-carboxymethyl)-bovine serum albumin. In men below 40 years of age the levels ranged from 0.85 to 2.80 ng/ml (mean +/- SEM: 1.52 +/- 0.11; n = 24) and from 0.50 to 2.20 ng/ml (mean +/- SEM: 0.93 +/- 0.09; n = 20) in men aged between 41 and 62 years. The mean level was significantly different (P less than 0.001) between the 2 groups. A significant correlation (r = -0.56; P less than 0.01) was demonstrated between age and all male levels. In females the mean plasma level was in the follicular phase: 0.81 +/- 0.07 ng/ml (range: 0.40-1.50; n = 17; age: 19-41 years) and in the luteal phase: 0.83 +/- 0.05 ng/ml (range: 0.40-1.30; n = 29; age: 18-43 years). No cyclical change and no correlation with age could be evidenced. A significant difference (P less than 0.001) was shown between females and the young male group. In breast cyst fluid the levels ranged from 0.05 to 13.70 ng/ml (mean +/- SEM: 2.36 +/- 0.86; n = 20) whereas the sulfate concentrations ranged from 75 to 7500 ng/ml (mean +/- SEM: 1891 +/- 565; n = 15), thus demonstrating very wide inter-individual variations.

Androstenediol↗