Biomedical subjects

R Scholler

Publications and source records attributed to R Scholler.

At least 19 recordsLinked to original sources

PubMed1992

Detection of HIV-1 infections by PCR: evaluation in a seropositive subject population.

To study the polymerase chain reaction (PCR) performance in detecting human immunodeficiency virus (HIV) infections, we tested 53 HIV-1 seropositive patients and 29 HIV-1 seronegative subjects for four different HIV-1 DNA regions. Fifty-one seropositive patients were found positive by PCR with at least one primer pair, but two were repeatedly negative for all primers. Weekly blood samples from 12 seropositive subjects all detected positive for at least one primer pair, but for three patients an irregular primer detection pattern was found. One additional HIV-1 seropositive sample, found negative for HIV DNA, was also negative for the beta-globin PCR control. The 29 seronegative specimens were HIV-1 DNA negative, as was a HIV-2 seropositive patient. This study demonstrates that PCR is almost as good as serological tests for detecting HIV infections, with a specificity of 100% and a sensitivity of 96% and that resampling the patients may improve detection performance.

Base Sequence↗

PubMed1992

Detection of hepatitis B virus DNA in serum by a nonisotopic hybridization technique.

We developed a nonisotopic technique, Hepagene, for measuring hepatitis B virus (HBV) DNA in human serum by using a sulfonated probe that is detected by a sandwich immunoenzymatic reaction. The detection limit, determined by serum dilution tests, was 2.5 ng/L. The precision of the Hepagene test was demonstrated by the accurate reproducibility observed for low (3 ng/L) and medium (38 ng/L) concentrations of HBV DNA assayed in 24 different series. Specificity was established by assaying HBV DNA in sera from 98 patients by the Hepagene technique or by a solution hybridization assay with an 125I-labeled probe. Results by both techniques agreed for 94 sera (96%), with 68 being concordant for HBV DNA negativity and 26 for positivity. HBV DNA titers assayed by both methods also agreed. Hepagene represents the first nonisotopic HBV DNA assay involving a sulfonated probe and with performance characteristics equivalent to those of classical radioactive hybridization techniques.

DNA Probes↗

PubMed1991

A simple technique for collecting blood of testicular origin: application to in vivo studies on testicular steroidogenesis in rats and Macaca fascicularis.

A technique for rapidly collecting blood of testicular origin is described, one which can provide sufficient plasma amounts to investigate some steps of testicular steroid biogenesis in vivo in 2 species. In adult male rats, testosterone (T), androstenedione (4A) and 5-androstenediol (5AD) were determined in pampiniform plexus testicular venous blood (PPTV) and peripheral (PV) blood samples before and 2 h after human Chorionic Gonadotropin (hCG). PPTV concentration of 5AD was 0.83 +/- 0.1 ng/ml (mean +/- SEM) with a PPTV/PV ratio of 7.0 +/- 1.0, comparable to a PPTV/PV ratio for 4A of 5.8 +/- 1.8. After hCG, PPTV concentration of 5AD significantly increased to 1.28 +/- 0.15 ng/ml (P less than 0.05). Those data are in favor of a participation of 5-ene pathway to testicular biogenesis of T associated to a 4-ene pathway which is predominant. In adult male Macaca fascicularis, spermatic vein (SV) concentrations of 5AD and 4A were comparable (3.0 +/- 1.2 vs 4.3 +/- 1.0 ng/ml) as well as SV/PV ratios under basal conditions (3.5 +/- 0.9 vs 5.1 +/- 0.1), as well as 48 h after hCG, confirming in vivo that both 5-ene and 4-ene pathways are involved in testicular T biogenesis. Testicular production of estradiol (E2), estrone (E1) and their sulfates E2S and E1S showed a SV/PV ratio significantly higher than 1 (3.4 +/- 0.6; 2.4 +/- 0.1; 1.7 +/- 0.2 and 1.6 +/- 0.2, respectively).

Androstenediol↗

PubMed1991

Testicular function in uremic rats: in vivo assessment of testosterone biogenesis.

The mechanism of testosterone (T) production defect in uremic rats has not yet been clearly defined and hypothalamo-hypophyseal impairment as well as primary testicular dysfunction have been suggested. In 42 rats followed monthly after subtotal nephrectomy up to 7.1 +/- 0.3 months, we observed a progressive significant decline of T and androstenedione (A) compared to control rats. Two months before the terminal phase of chronic renal failure (CRF), T/A ratio abruptly declined. T and its precursors on the 4-ene pathway, A, progesterone (P) and 17-hydroxyprogesterone were evaluated in pampiniform plexus testicular vein (PPTV) and in peripheral blood (PV) in end stage uremic rats (blood urea greater than 30 mmol/l, creatinine clearance less than 0.5 ml/min). Under basal conditions, all steroids but peripheral P were significantly lower in uremic rats than in controls as well as T/P and A/P ratios. After human chorionic gonadotropin (hCG) stimulation, T concentration in PV and PPTV remained highly significantly lower than in controls whereas T precursor concentrations were partially corrected by hCG administration. T/P ratio remained lower than in controls whereas A/P ratio was not significantly lower than in controls. Those data show a decline in all the steps of T biogenesis in uremic rats in basal conditions. The defect in 17 beta-hydroxysteroid dehydrogenase evidenced by T/A decrease at the end stage of CRF seems of primary testicular origin as it is not corrected by hCG administration as shown by T/P and A/P ratios in PPTV and in PV.

17-alpha-Hydroxyprogesterone↗

PubMed1990

[Comparison of four human growth hormone (hGH) immunoassay kits and analysis of recognition of circulating forms].

Three immunoradiometric assay (IRMA) kits (Pharmacia, bioMérieux and Cis-ELISA) and one competitive radioimmunoassay (RIA) kit (Cis-SB) designed for routine hGH quantitation were compared. Reproducibility was better with the IRMAs than with the RIA, especially when hGH levels were low (less than 3 mUI/l). This substantial advantage was responsible for a decrease in the qualitative detection threshold from 1.22 mUI/l for the RIA to approximately 0.08 mUI/l for the IRMAs. Analysis of accuracy showed that the Cis-ELSA kit overestimated recovery of added hGH (1st IRP 66/217) and demonstrated a marked influence of matrix effects with Cis-ELSA and Cis-SB. Pharmacia and bioMérieux kits were more accurate and showed less sensitivity to matrix effects. hGH concentrations obtained with the four kits were determined in 113 normal or abnormal sera. Despite the above-mentioned differences in accuracy, the three IRMAs yielded comparable results. Concentrations measured using the RIA were higher than those obtained with the other kits. Two sera were submitted to gel filtration chromatography. hGH assays in the fractions obtained showed that the immunologic systems used in the kits display different levels of immunoreactivity towards the circulating oligomeric and dimeric forms of hGH that they recognize. These data suggest that normal reference values should be established for each kit.

Growth Disorders↗

PubMed1990

[Detection of self-administration of testosterone as an anabolic by determination of the ratio of urinary testosterone to urinary epitestosterone in adolescents].

Testing for illicit self-administration of testosterone by athletes requires quantitative analysis by gas chronomatography-mass spectrometry combined with stable isotope dilution. International Sports Authorities have adopted the ratio of urinary excretions of testosterone and epitestosterone for drug testing. This ratio is required to be under 6. The authors studied the statistical distribution of this ratio in teenage athletes and found that the likelihood of false-positive results is 15/10,000.

Adolescent↗

PubMed1989

[Free alpha-subunit glycoprotein hormones: physiological and pathological data].

The glycoprotein hormone alpha-subunit is secreted as a free molecule as well as a molecule combined to a glycoprotein hormone beta-subunit. In human subjects, plasma levels of the free alpha-subunit were measured by means of a specific radioimmunoassay. Plasma concentrations were high during the neonatal period, then decreased to a nadir at the age of 6 years. A significant pubertal increase occurred in both sexes, more pronounced in girls. In female subjects mean levels (+/- SEM) were 0.21 +/- 0.05 before puberty and 0.51 +/- 0.03 ng 1 degrees IRP-hCG alpha/ml in follicular phase. During menstrual cycle, a typical preovulatory surge was seen simultaneous with the LH surge. During aging, plasma levels increased slowly in males, abruptly in menopausal females. The pituitary reserve as assessed by LH-RH stimulation test (100 micrograms i.v./m2) exhibited a significant pubertal maturation in boys and girls. Chronic administration of LH-RH agonist induced a marked increase of alpha-subunit levels, whereas LH levels were deeply suppressed. LH-RH injections in children treated for precocious puberty with a LH-RH agonist induced a significant release of alpha-subunit despite an almost complete abolition of LH release. In conclusion, from a quantitative point of view, the glyco-protein hormone alpha-subunit is a major secretory product of the pituitary. It seems that there is a specific regulation of its secretion, resembling but not identical to LH secretion regulation. Whether or not it plays a biological role remains uncertain.

Child↗

PubMed1989

[Determination of EGF receptors (epidermal growth factor) in the placenta and breast tumors].

Receptors for Epidermal Growth Factor (EGF) have been identified in different types of tumors and they are often associated with other characteristics which are related to a bad prognosis. A technic has been established to measure membrane receptors in human placenta, which is appropriate for the study of tumors. Preparations of placental membranes were incubated either with increasing amounts (0.1 to 3.0, 10(-9) M) of EGF labeled with 125I (method by saturation) or with 0.2, 10(-9) M labeled EGF and increasing concentrations (0 to 1.6, 10(-9) M) of cold EGF (method by competition). The KD obtained with both technics are not significantly different: 0.85 and 0.77, 10(-9) M respectively, as well as the maximum binding capacity: 5.9 and 4.4 pmol/mg protein respectively. A preliminary study in breast tumors showed that 2 out of 9 contained significant amounts of receptors (58 and 114 fmol/mg protein). One of these two tumors held both estradiol and progesterone receptors. In the other 7 tumors without EGF receptors only one did not contained any estradiol or progesterone receptors. Further studies are needed to evaluate the relationships between EGF/sex hormone receptor status and the degree of breast tumor malignancy.

Breast Neoplasms↗

PubMed1989

[Assay of plasma progesterone and testosterone. Comparison of enzyme immunoassays and radio-immunoassays].

Plasma progesterone (P) and testosterone (T) were determined by enzyme immunology with commercially available kits. Two kits (Serono and BioMérieux) were studied for P determination and one kit (Serono) for that of the T. The results obtained by either enzyme immunoassay were compared reliable and specific radioimmunoassays. The BioMérieux kit was shown to be more appropriate than the Serono kit for plasma P assay except in patients after oral administration of micronized progesterone because of the interference of the high levels of P metabolites. Concerning T, the Serono kit appears to yield generally adequate results in male adults but neither in men treated with dihydrotestosterone nor in females.

Humans↗

PubMed1988

Interactions between 17 beta-estradiol and the hypothalamo-pituitary beta-endorphin system in the regulation of the cyclic LH secretion.

This paper further substantiates the physiological role of beta-endorphin (beta-END) in the control of the cyclic LH secretion and provides new data on the interactions between 17 beta-estradiol (17 beta-E2) and beta-END at both the hypothalamic and pituitary levels. At the hypothalamic level, during the estrous cycle in rats, beta-END concentrations were highest on diestrus I in the arcuate nucleus, median preoptic area and median eminence and lowest at the time of the preovulatory 17 beta-E2 surge on proestrus, before the subsequent preovulatory hypothalamic GnRH and plasma LH surges. Data obtained in ovariectomized 17 beta-E2-treated ewes support the direct involvement of 17 beta-E2 in changes in beta-END and GnRH concentrations in these hypothalamic areas. At the anterior pituitary level, in vitro results obtained using anterior pituitaries from the proestrus morning cycling female rat have shown that 17 beta-E2 strongly suppresses beta-END secretion and that GnRH stimulates the release of beta-END. Furthermore, marked fluctuations were observed for plasma beta-END throughout the menstrual cycle in the woman. Low beta-END concentrations were observed in the period preceding the LH preovulatory surge. Taken together, these results show that: (1) decreases in hypothalamic beta-END concentrations, which are controlled at least by circulating levels of 17 beta-E2, modulate GnRH synthesis and/or release and contribute to the mechanisms which initiate the LH surge; (2) anterior pituitary beta-END might be involved in the mechanisms which terminate the LH surge.

Animals↗

PubMed1988

Plasma corticosteroid patterns in the fetus.

In umbilical vein blood samples collected in 137 fetuses between 19 and 31 weeks of gestation, cortisol (F), cortisone (E), 17-hydroxyprogesterone (17-OHP) and 11-deoxycortisol (S) were radioimmunoassayed after column chromatography on Sephadex LH-20 of plasma extracts. While F levels plateaued throughout the period considered those of E displayed an increasing pattern which appeared to be comparable with that of unbound F in pregnant women. The declining pattern of S and more particularly of 17-OHP would suggest an increasing utilization and metabolization of these F precursors by the maturing fetus. E was not correlated with either 17-OHP or S but showed a significant correlation with F. S and 17-OHP were correlated with each other and with F. The significance of these correlations was discussed according to the different origin of these steroids and to their metabolic relationships. The application of this method for the prenatal diagnosis of inborn errors of steroid biogenesis is suggested.

17-alpha-Hydroxyprogesterone↗

PubMed1988

Deoxycorticosterone secretion by the human ovary.

Progesterone (P), deoxycorticosterone (DOC), estradiol-17 beta (E2) and cortisol (F) were determined simultaneously in the peripheral and the ovarian veins in 13 patients. Blood was collected either by direct sampling during laparotomy (12 patients) or by selective catheterization (1 patient). In all ovarian effluents P and E2 levels were significantly higher than in the peripheral vein. This was also true for DOC except in one ovarian effluent. The gradient was higher on the side of the corpus luteum-bearing ovary. P and E2 levels were correlated in ovarian as well as in peripheral veins. In ovarian effluents, DOC gradients were only significantly correlated with P levels (r = 0.63; P less than 0.01) suggesting a metabolic relationship between the two steroids.

Adult↗

PubMed1988

Experimental control of the differentiation of Leydig cells in the rat fetal testis.

In the developing fetal testis, in vitro as well as in vivo, two kinds of endocrine cells differentiate successively: Sertoli cells, which produce the Müllerian inhibitor (or anti-Müllerian hormone) and aggregate with germ cells into seminiferous cords; and Leydig cells, which release androgens. Serum added to the synthetic culture medium prevents the morphogenesis of the seminiferous cords but not the cytodifferentiation of the endocrine cells. L-Azetidine 2-carboxylic acid (LACA), a proline competitor, introduced into the medium also prevents differentiation of seminiferous cords. In the present experiments, the effects of LACA on the endocrine cells were studied. It did not suppress production of the Müllerian inhibitor, but it opposed differentiation of Leydig cells. Histochemically detectable 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) was virtually absent and the release of testosterone, delta 4-androstenedione, 17-hydroxyprogesterone, or progesterone into the medium became undetectable. Moreover, dibutyryl cAMP added to the medium during the final day in vitro had very little effect on the parameters of steroidogenesis. An excess of proline added to the LACA-containing medium permitted normal morphogenesis of seminiferous cords, normal steroidogenesis, and normal response to cAMP. LACA did not prevent the appearance of 3 beta-HSD activity in the adrenals, nor did it reduce the expression of laminin and fibronectin (data not shown) in the mesonephric structures as much as in the testes. The differentiation of the testis and especially of the Leydig cells appears to have special requirements for proline.

17-alpha-Hydroxyprogesterone↗

PubMed1988

Monoclonal antibody labelling of human spermatozoa: an electron microscope study.

The antigenic determinants recognized by six anti-human sperm monoclonal antibodies were localized at the subcellular level using an indirect peroxidase immunoelectron microscopic method. Labelling was performed using fresh spermatozoa, and after cell permeabilization (by osmotic shock or freeze-thawing) or detergent demembranation. Two antibodies bound to distinct regions of the plasma membrane, one over the acrosome and the other on the tail, but both also bound to intracellular sites on damaged cells. The internal organelles labelled by the other four antibodies were identified as the acrosomal membrane of the equatorial segment, structures in the connective piece, mitochondrial membranes and axonemal microtubules, respectively. These results are compared with those of a previous immunofluorescence study (Villarroya & Scholler, 1986) and the advantages of joint light and electron microscopy for sperm immunocytochemistry are discussed.

Antibodies, Monoclonal↗

PubMed1988

Effect of melatonin implantation on the seasonal variation of FSH secretion in the male blue fox (Alopex lagopus).

A heterologous radioimmunoassay system developed for the sheep was shown to measure FSH in the plasma of the blue fox. FSH concentrations throughout the year showed a circannual rhythm with the highest values (61.6 +/- 14.8 ng/ml) occurring shortly before or at the onset of the mating season, a pattern similar to that of LH. The concentration of FSH then declined when androgen concentrations and testicular development were maximal at the time of the mating season (March to May). Thereafter, concentrations remained low (25.2 +/- 4.1 ng/ml) in contrast to those of LH. Implantation of melatonin in August and in February maintained high plasma values of FSH after the mating season (142.3 +/- 16.5 ng/ml) in association with a maintenance of testicular development and of the winter coat. The spring rise of prolactin was suppressed by melatonin treatment. The release of FSH after LHRH injection was also increased during this post-mating period in melatonin-treated animals, in contrast to the response of the control animals which remained low or undetectable. These results suggest that changes both in the secretions of FSH and prolactin may be involved in the prolongation of testicular activity and in the suppression of the spring moult after melatonin administration.

Animals↗

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↗