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Biomedical subjects

J F Guerin

Publications and source records attributed to J F Guerin.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effect of gastrin-releasing peptide on sperm functions.

Male infertility can be related to defects in motility, capacitation, acrosome reaction, binding and penetration of the zona pellucida. While different in-vitro techniques (such as micromanipulation which is complicated and expensive) are available for the treatment of male infertility, several pharmacological agents have been shown to increase fertilizing capacity under accurate experimental conditions. Gastrin-releasing peptide (GRP, the mammalian homologue of the amphibian skin peptide bombesin) is present in the reproductive tract and expressed by the pregnant ovine endometrium prior to attachment and throughout the pregnancy. A bombesin-like peptide resulting from alternate splicing of the GRP gene in testis has been detected in primates. In this study, we have tested the ability of GRP to enhance human sperm functions such as motility, capacitation, zona binding and acrosome reaction. Analysis of sperm motility was performed with the ATS 20 computer-assisted semen analysis (CASA) system. Zona binding was analysed using intact human unfertilized oocytes and selective labelling of spermatozoa with two fluorochromes. Our results did not show any positive effect of GRP on these parameters under our experimental conditions. However, when GRP at the concentration of 100 nM was added after ionophore treatment, the percentage of reacted cells increased. significantly (P < 0.05) compared with situations where each agent was used alone. This led us to suppose that the role of bombesin in the different stages of fertilization might not exclude other unknown factors.

Acrosome↗
PubMed1994

Relationship between semen characteristics, alpha-glucosidase and the capacity of spermatozoa to bind to the human zona pellucida.

Unfertilized oocytes from an in-vitro fertilization programme were stored in different saline solutions and then utilized in a zona binding assay (ZBA). The four saline solutions tested were identical with regard to the capacity of the zona to bind spermatozoa provided by healthy donors. Spermatozoa from 150 infertile patients were tested in the ZBA. The number of spermatozoa bound to the zona correlated positively with sperm concentration, the percentage sperm motility and the percentage of morphologically normal spermatozoa. The population was then divided into two groups according to the level of alpha-glucosidase activity, an epididymal marker. The average number of spermatozoa bound to the zona was diminished in the group with low alpha-glucosidase activity, even when considering strictly equivalent classes of sperm concentration, motility and morphology, respectively.

Biomarkers↗
PubMed1992

Spontaneous and ionophore induced acrosome reaction in asthenozoospermic infertile semen.

Spontaneous and ionophore-induced ability of spermatozoa to acrosome-react was examined in asthenozoospermic infertile patients and fertile donors. Spermatozoa were washed free of seminal plasma and capacitated in B2 medium for 2 h at 37 degrees C. Subsequently 5, 10, 20 and 30 microM A23187 (final concentrations) were added to equal aliquots of these samples and incubated for an additional 30 min. The acrosome reaction was then determined by the triple stain technique. The percentage of spontaneous reaction (no ionophore) in asthenozoospermic samples was similar to that in fertile samples (4.2 and 3.8, respectively). However, the ionophore-induced reaction rate remained significantly lower in asthenozoospermic samples than in normozoospermic samples.

Acrosome↗
PubMed1991

Hyperactivated motility of sperm from fertile donors and asthenozoospermic patients before and after treatment with ionophore.

Hyperactivated motility of capacitated sperm was studied before and after contact for 30 min with the Ca2+ ionophore A23187. Sperm from fertile donors and asthenozoospermic infertile patients were incubated in the presence of increasing concentrations of A23187 in the medium. At 5-10 microM, the ionophore induced a significant increase (P less than 0.05) in the percentage of hyperactivation of sperm from asthenozoospermic subjects. Higher concentrations (20 and 30 microM) were needed to enhance hyperactivation of sperm in the fertile population. In the latter, extended contact with the ionophore induced no significant change compared to a 30-min incubation period. Since this type of movement is an essential feature of the fertilizing gamete, a low hyperactivation rate may partly explain fertilization failure in the asthenozoospermic group.

Calcimycin↗
PubMed1991

Movement characteristics and hyperactivation of human sperm on different epithelial cell monolayers.

Studies of sperm movement characteristics concern mainly sperm swimming between two glass surfaces (as in the Makler chamber). Using automated videomicrography, (CellSoft, Cryo Resources, New York, USA), we have analysed the movements of human sperm swimming on monolayers of different origins: monkey kidney (Vero) cells, bovine oviduct cells, and human endometrial cells. About 10(5) sperm were deposited upon preparations consisting of monocellular layers adhering to a coverglass, and placed in a deep slide-coverglass system. Experiments were first performed at room temperature then at 37 degrees C. At room temperature, motion characteristics on Vero cell layers (six samples) were not different from those measured in either the conditioned or corresponding non-conditioned media, except for the amplitude of lateral head displacement (ALH) which was significantly lower. Comparison of the three different cell monolayers showed no difference between them for the corresponding motion parameters. The data were dramatically different at 37 degrees C: sperm swimming on cell monolayers of genital origin (oviduct or endometrium) exhibited high rates of hyperactivation (HA: 36.7% and 38.6% respectively), which was significantly more than on either Vero cells (10.9%) or in a control medium (12.6%). Moreover, HA rates were significantly higher on genital cell monolayers than in the corresponding conditioned medium. Hyperactivated sperm exhibited lasting 'star-spin' trajectories rather than 'transitional phases'. It is concluded that passage of sperm on either oviduct or endometrial epithelial cell monolayers can induce sperm hyperactivation and improve their fertilizing capacity.

Animals↗
PubMed1990

Transfers of frozen-thawed human embryos in cycles stimulated by HMG.

A total of 130 transfers of frozen-thawed (F-T) human embryos was carried out after moderate ovarian stimulation with human menopausal gonadotrophin (HMG). Embryos were replaced 3 days after the spontaneous luteinizing hormone (LH) surge or 4 days if ovulation was induced by human chorionic gonadotrophin (HCG). Embryos were thawed a few hours prior to transfer. One-hundred-and-twenty-three transfers were effective and 23 pregnancies were achieved. The rate of ongoing pregnancies per transfer was 17.9% (22/123). The survival rate of embryos originating from cycles stimulated by a combination of an LHRH analogue and HMG in a long protocol (LA-HMG protocol) was significantly lower when compared with the rate of embryos retrieved from clomiphene citrate-HMG (CC-HMG protocol) stimulated cycles (52 versus 67%, P less than 0.05). When fresh embryos originated from cycles stimulated with an LHRH analogue and HMG in a short protocol (SA-HMG protocol), the survival rate was not affected (59 versus 67%, NS). Although the difference was not significant, the ongoing pregnancy rate per transfer according to the three protocols from which the embryos originated seemed to be better with the SA-HMG protocol: 16% with the CC-HMG protocol, 14.5% with the LA-HMG protocol versus 27.6% with the SA-HMG protocol. The success rate was independent of the number of F-T transferred embryos if at least one embryo with 100% intact blastomeres was replaced.

Cryopreservation↗
PubMed1990

Improvement of human early embryo development in vitro by coculture on monolayers of Vero cells.

Human "spare" embryos, judged unsuitable for freezing because of their poor quality, were cocultured for 5 days on a "Vero" cell layer. These epithelial cells were selected because kidney and genital tract have a common embryologic origin and "Vero" cells are a safe and highly controlled cellular support used for vaccine production. In the control group, the embryos were cultured in culture medium alone (B2 + 15% serum). At the end of the culture, the number of blastocysts was significantly higher in the coculture group: 61% vs. 3%. Moreover, at least half of the blastocysts were expanding and hatching (13/25), with a chronologically normal development. These observations suggest that (1) the coculture system improves human embryonic development; (2) it can rescue early degenerating embryos; (3) beneficial effects of coculture are not strictly genital-tract specific, but rather epithelium dependent. This coculture system could be used for in vitro fertilization to prolong in vitro culture and thus make it possible to transfer embryos at a more appropriate time, to eliminate early-blocked eggs, and to freeze embryos at the blastocyst stage, when freezing procedures are most successful.

Animals↗
PubMed1989

Stimulation of motility and energy metabolism of spermatozoa from asthenozoospermic patients by 17 beta-estradiol.

Spermatozoa from nine asthenozoospermic patients were incubated for 3 h in Krebs Phosphate Ringer (KRP), supplemented or not with 17 beta-estradiol. 17 beta-estradiol increased the mean velocity and maintained the percentage of motility during the first 2 h of incubation. Oxydative metabolism and intracellular ATP concentrations were enhanced, too, whereas glycolysis remained unchanged.

Cell Survival↗
PubMed1988

Inhibition of spermatogenesis in men using various combinations of oral progestagens and percutaneous or oral androgens.

Eight men (experiment 1) requesting male contraception received a daily oral dose of 20 mg medroxyprogesterone acetate (MPA) combined with 125 mg percutaneous dihydrotestosterone (DHT). Three months later the mean sperm count was only diminished slightly; the replacement of DHT for four men by percutaneous testosterone at the same concentration led to a dramatic fall in sperm count. For 6-18 months all men were treated with MPA plus percutaneous testosterone (250 mg daily). The latter dose restored physiological levels of plasma testosterone. Follicle-stimulating hormone levels were inhibited more severely than in the DHT-treated group, whereas LH levels were variable. Azoospermia was achieved and maintained in six cases; two men were oligozoospermic and in one case a moderate secondary rise in the sperm count was observed. Twelve volunteers (experiment 2) received a daily oral dose of either 5 or 10 mg norethisterone acetate plus percutaneous testosterone (250 mg daily). All of them achieved azoospermia within 2 months, but two subjects later exhibited a partial restoration in sperm count. Follicle-stimulating hormone and LH levels were inhibited more severely than in the first experiment. The sperm count and gonadotrophin levels returned to initial values within 6 months after cessation of the treatment in both experiments. No side-effects were noted concerning blood parameters, libido or body weight. However, several female partners had elevated levels of plasma testosterone. In experiment 3 (13 volunteers), percutaneous testosterone was replaced by oral testosterone undecanoate (160 mg daily). Only seven men were azoospermic and most of them had lowered levels of plasma testosterone. Thus, the combination of percutaneous testosterone and oral progestagens appears to be the most convenient for male hormonal contraception.

Administration, Cutaneous↗
PubMed1987

In vitro behavior of human nonfertile semen in isoosmotic and hyperosmotic media.

High-ionic-strength media are known to favor rapid capacitation and acrosome reaction of spermatozoa in vitro. The influence of isoosmolar (N-BWW) and hyperosmolar (H-BWW) media on the percent motility, forward progression, and zona-free hamster egg penetration has been investigated for 148 semen from patients consulting for male or idiopathic sterility. After 15 h of incubation, the hyperosmotic medium had no significant detrimental effect on the percent motility of spermatozoa, although the forward progression was better maintained in the isoosmolar medium. In general egg penetration was increased when spermatozoa were treated with the hypertonic medium, and in particular 5 patients whose semen showed no penetration when treated with N-BWW scored greater than 12% when treated with H-BWW. For the 23 subjects who had an IVF at the same period, a good agreement with zona-free egg penetration was found in 70% of the cases.

Animals↗
PubMed1987

Effects of estradiol and its antagonist tamoxifen on motility and metabolism of human spermatozoa.

An investigation was conducted to evaluate the motility and metabolism of human spermatozoa incubated at 37 degrees Celsius for 3 hours in a krebs phosphate Ringer solution containing different concentrations of 17beta-estradiol and tamoxifen. 17beta-estradiol (17beta E2) stimulated significantly the motility of human spermatozoa. The oxidative metabolism and the intracellular ATP concentrations are enhanced with 10-20 mcg/ml of 17beta E2; the lactate production remains unchanged however. Tamoxifen, an antiestrogen, inhibited the motility of spermatozoa, and was toxic at high concentrations. Its effects on the energetic metabolism is dose-dependent; it increases the oxidative metabolism and decreases the lactate production and intracellular ATP at 3 mcg/ml.

Biology↗
PubMed1986

Objective evaluation of fibrosis in human testicular biopsies by analysis based on optical diffractometry.

Bilateral testicular biopsies were obtained from 27 patients and submitted to two different treatments for each of them: firstly, a classical fixation and colouring, permitting the histopathological diagnosis and subjective appreciation of the degree of fibrosis; secondly, a new objective technique based on optical diffractometry: this method is based on the analysis of light intensity distribution in the diffraction pattern of an original image. Using two different methods of discriminant analysis, we observed some errors due to the subjective examination; in particular, several fibrosed samples had been judged as 'normal' by the histopathologist. Moreover, we showed the existence of some heterogeneity between different slides from the same original biopsy.

Biopsy↗
PubMed1986

Glycolytic activity of human spermatozoa in normospermic men and in men with abnormal spermograms.

The glycolytic activity of human spermatozoa was studied in samples from supposed fertile and infertile subjects. The quantity of L-lactate produced during the first hour of incubation in an enriched medium was measured. There was no difference between the oligozoospermic subjects and the volunteer donors constituting the control group. Lactate production was considerably decreased in men consulting for sterility but with a normal sperm examination, as well as in asthenozoospermic men. In oligoasthenozoospermic men abnormally high quantities of lactate were present in samples from certain individuals or it was unexpected, reflecting extensive metabolic disturbances. Positive correlations were noted between motility and glycolysis only in the controls. A negative correlation was noted between the concentration of spermatozoa and their metabolic activity, especially evident in oligoasthenozoospermic men.

Glycolysis↗
PubMed1986

Acrosome-reacting capacity of frozen-thawed human semen: relation to hamster ova penetration.

Interspecies egg penetration requires completion of capacitation and acrosome reaction of the spermatozoa. The ability of frozen-thawed human semen to accomplish this reaction was studied, and its relation to the zona-free hamster egg penetration was investigated. The percentage of reacted cells in the population of live spermatozoa estimated by the triple-staining technique was found to be greater in frozen than in fresh samples. However, the egg-penetrating ability of cryopreserved semen remained significantly low. Individual differences in the ability to undergo the acrosome reaction and its relation to penetration are discussed.

Acrosome↗
PubMed1983

Influence of cations and albumin on human spermatozoa.

The effects of potassium, calcium and magnesium cations, and albumin on motility of spermatozoa, were tested after 15 min, 4 hr, and 24 hr of incubation using laser Doppler velocimetry. The optimal concentration of K+ was found to be 11 mM; higher values decreased motility more severely than did lower ones, even when K+ was completely removed. Motility was increased in the presence of small amounts of calcium (from 0.8-1.7 mM) but was depressed by magnesium concentrations above 0.8 mM. Moderate concentrations of albumin (0.5-1%) improved motility, but the protecting effect of this compound--leading to a best sperm survival--appeared with higher concentrations (4%). In conclusion we observed that optimal ionic conditions presently found were corresponding well to the tubal environment in preovulatory phase.

Albumins↗